JP6448525B2 - Non-aqueous electrolyte secondary battery negative electrode active material, non-aqueous electrolyte secondary battery negative electrode, non-aqueous electrolyte secondary battery, and method for producing non-aqueous electrolyte secondary battery negative electrode material - Google Patents

Non-aqueous electrolyte secondary battery negative electrode active material, non-aqueous electrolyte secondary battery negative electrode, non-aqueous electrolyte secondary battery, and method for producing non-aqueous electrolyte secondary battery negative electrode material Download PDF

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JP6448525B2
JP6448525B2 JP2015229550A JP2015229550A JP6448525B2 JP 6448525 B2 JP6448525 B2 JP 6448525B2 JP 2015229550 A JP2015229550 A JP 2015229550A JP 2015229550 A JP2015229550 A JP 2015229550A JP 6448525 B2 JP6448525 B2 JP 6448525B2
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博道 加茂
博道 加茂
健太 藤崎
健太 藤崎
拓史 松野
拓史 松野
貴一 廣瀬
貴一 廣瀬
吉川　博樹
博樹 吉川
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Shin Etsu Chemical Co Ltd
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Description

本発明は、非水電解質二次電池用負極活物質、これを含む非水電解質二次電池用負極及び非水電解質二次電池、並びに非水電解質二次電池用負極材の製造方法に関する。   The present invention relates to a negative electrode active material for a non-aqueous electrolyte secondary battery, a negative electrode for a non-aqueous electrolyte secondary battery and a non-aqueous electrolyte secondary battery including the same, and a method for producing a negative electrode material for a non-aqueous electrolyte secondary battery.

近年、モバイル端末などに代表される小型の電子機器が広く普及しており、さらなる小型化、軽量化及び長寿命化が強く求められている。このような市場要求に対し、特に小型かつ軽量で高エネルギー密度を得ることが可能な二次電池の開発が進められている。この二次電池は、小型の電子機器に限らず、自動車などに代表される大型の電子機器、家屋などに代表される電力貯蔵システムへの適用も検討されている。   In recent years, small electronic devices typified by mobile terminals have been widely used, and further downsizing, weight reduction, and long life have been strongly demanded. In response to such market demands, development of secondary batteries capable of obtaining a high energy density, in particular, being small and light is underway. This secondary battery is not limited to a small electronic device, but is also considered to be applied to a large-sized electronic device represented by an automobile or the like, or an electric power storage system represented by a house.

その中でも、リチウムイオン二次電池は小型化及び高容量化が行いやすく、また、鉛電池、ニッケルカドミウム電池よりも高いエネルギー密度が得られるため、大いに期待されている。   Among them, lithium ion secondary batteries are highly expected because they are easy to miniaturize and increase capacity, and can obtain higher energy density than lead batteries and nickel cadmium batteries.

リチウムイオン二次電池は、正極及び負極、セパレータと共に電解液を備えている。この負極は充放電反応に関わる負極活物質を含んでいる。   A lithium ion secondary battery includes an electrolyte solution together with a positive electrode, a negative electrode, and a separator. This negative electrode contains a negative electrode active material involved in the charge / discharge reaction.

負極活物質としては、炭素材料が広く使用されている一方で、最近の市場要求から、電池容量のさらなる向上が求められている。電池容量向上の要素として、負極活物質材として、ケイ素を用いることが検討されている。ケイ素の理論容量（４１９９ｍＡｈ／ｇ）は黒鉛の理論容量（３７２ｍＡｈ／ｇ）よりも１０倍以上大きいため、電池容量の大幅な向上を期待できるからである。負極活物質材としてのケイ素材の開発はケイ素単体だけではなく、合金、酸化物に代表される化合物などについても検討されている。活物質形状は炭素材で標準的な塗布型から、集電体に直接堆積する一体型まで検討されている。   As a negative electrode active material, while carbon materials are widely used, further improvement in battery capacity is required due to recent market demand. As an element for improving battery capacity, the use of silicon as a negative electrode active material has been studied. This is because the theoretical capacity of silicon (4199 mAh / g) is 10 times or more larger than the theoretical capacity of graphite (372 mAh / g), so that significant improvement in battery capacity can be expected. The development of a siliceous material as a negative electrode active material has been examined not only for silicon itself but also for compounds represented by alloys and oxides. The shape of the active material is studied from a standard coating type of carbon material to an integrated type directly deposited on a current collector.

しかしながら、負極活物質としてケイ素を主原料として用いると、充放電時にケイ素系活物質粒子が膨張収縮するため、主にケイ素系活物質粒子の表層近傍で割れやすくなる。また、活物質内部にイオン性物質が生成し、ケイ素系活物質粒子が割れやすくなる。負極活物質表層が割れることで新生面が生じ、活物質の反応面積が増加する。この時、新生面において電解液の分解反応が生じるとともに、新生面に電解液の分解物である被膜が形成されるため電解液が消費される。このためサイクル特性が低下しやすくなる。   However, when silicon is used as the negative electrode active material as the main raw material, the silicon-based active material particles expand and contract during charge / discharge, and therefore, the silicon-based active material particles tend to break mainly in the vicinity of the surface layer. Further, an ionic material is generated inside the active material, and the silicon-based active material particles are easily broken. When the negative electrode active material surface layer is cracked, a new surface is generated and the reaction area of the active material is increased. At this time, a decomposition reaction of the electrolytic solution occurs on the new surface, and a coating film that is a decomposition product of the electrolytic solution is formed on the new surface, so that the electrolytic solution is consumed. For this reason, the cycle characteristics are likely to deteriorate.

これまでに、電池初期効率やサイクル特性を向上させるために、ケイ素材を主材としたリチウムイオン二次電池用負極材料、電極構成についてさまざまな検討が成されている。   To date, various studies have been made on negative electrode materials and electrode configurations for lithium ion secondary batteries mainly composed of a siliceous material in order to improve battery initial efficiency and cycle characteristics.

具体的には、良好なサイクル特性や高い安全性を得る目的で、気相法を用いケイ素及びアモルファス二酸化ケイ素を同時に堆積させている（例えば特許文献１参照）。また、高い電池容量や安全性を得るために、ケイ素酸化物粒子の表層に炭素材（電子伝導材）を設けている（例えば特許文献２参照）。更に、サイクル特性を改善するとともに高入出力特性を得るために、ケイ素及び酸素を含有する活物質を作製し、かつ集電体近傍での酸素比率が高い活物質層を形成している（例えば特許文献３参照）。また、サイクル特性を向上させるために、ケイ素活物質中に酸素を含有させ、平均酸素含有量が４０ａｔ％以下であり、かつ集電体に近い場所で酸素含有量が多くなるように形成している（例えば、特許文献４参照）。   Specifically, for the purpose of obtaining good cycle characteristics and high safety, silicon and amorphous silicon dioxide are deposited simultaneously using a vapor phase method (see, for example, Patent Document 1). Further, in order to obtain a high battery capacity and safety, a carbon material (electron conductive material) is provided on the surface layer of the silicon oxide particles (see, for example, Patent Document 2). Furthermore, in order to improve cycle characteristics and obtain high input / output characteristics, an active material containing silicon and oxygen is produced, and an active material layer having a high oxygen ratio in the vicinity of the current collector is formed (for example, (See Patent Document 3). Further, in order to improve the cycle characteristics, oxygen is contained in the silicon active material, the average oxygen content is 40 at% or less, and the oxygen content is increased at a location close to the current collector. (For example, see Patent Document 4).

また、初回充放電効率を改善するためにＳｉ相、ＳｉＯ２、ＭｙＯ金属酸化物を含有するナノ複合体を用いている（例えば特許文献５参照）。また、初回充放電効率を改善するためにＬｉ含有物を負極に添加し、負極電位が高いところでＬｉを分解しＬｉを正極に戻すプレドープを行っている（例えば特許文献６参照）。 Further, Si phase, (for example, see Patent Document 5) by using a nanocomposite containing SiO 2, M y O metal oxide in order to improve the initial charge and discharge efficiency. In order to improve the initial charge / discharge efficiency, a Li-containing material is added to the negative electrode, and pre-doping is performed to decompose Li and return Li to the positive electrode when the negative electrode potential is high (see, for example, Patent Document 6).

また、サイクル特性改善のため、ＳｉＯｘ（０．８≦ｘ≦１．５、粒径範囲＝１μｍ〜５０μｍ）と炭素材を混合し高温焼成している（例えば特許文献７参照）。また、サイクル特性改善のために、負極活物質中におけるケイ素に対する酸素のモル比を０．１〜１．２とし、活物質と集電体との界面近傍における、ケイ素量に対する酸素量のモル比の最大値と最小値との差が０．４以下となる範囲で活物質の制御を行っている（例えば、特許文献８参照）。また、電池負荷特性を向上させるため、リチウムを含有した金属酸化物を用いている（例えば特許文献９参照）。また、サイクル特性を改善させるために、ケイ素材表層にシラン化合物などの疎水層を形成している（例えば、特許文献１０参照）。   Further, in order to improve cycle characteristics, SiOx (0.8 ≦ x ≦ 1.5, particle size range = 1 μm to 50 μm) and a carbon material are mixed and fired at a high temperature (for example, see Patent Document 7). Further, in order to improve cycle characteristics, the molar ratio of oxygen to silicon in the negative electrode active material is 0.1 to 1.2, and the molar ratio of oxygen amount to silicon amount in the vicinity of the interface between the active material and the current collector The active material is controlled in a range where the difference between the maximum value and the minimum value is 0.4 or less (see, for example, Patent Document 8). Further, in order to improve battery load characteristics, a metal oxide containing lithium is used (see, for example, Patent Document 9). In addition, in order to improve cycle characteristics, a hydrophobic layer such as a silane compound is formed on the surface of the siliceous material (see, for example, Patent Document 10).

また、サイクル特性改善のため、酸化ケイ素を用い、その表層に黒鉛被膜を形成することで導電性を付与している（例えば、特許文献１１参照）。この場合、特許文献１１では、黒鉛被膜に関するラマンスペクトルから得られるシフト値に関して、１３３０ｃｍ−１及び１５８０ｃｍ−１にブロードなピークが現れるとともに、それらの強度比Ｉ１３３０／Ｉ１５８０が１．５＜Ｉ１３３０／Ｉ１５８０＜３である。 In order to improve cycle characteristics, silicon oxide is used and conductivity is imparted by forming a graphite film on the surface layer (see, for example, Patent Document 11). In this case, in Patent Document 11, with respect to the shift value obtained from the Raman spectra for graphite coating, with broad peaks appearing at 1330 cm -1 and 1580 cm -1, their intensity ratio I 1330 / I 1580 is 1.5 <I 1330 / I 1580 <3.

また、高い電池容量、サイクル特性の改善のため、二酸化ケイ素中に分散されたケイ素微結晶相を有する粒子を用いている（例えば、特許文献１２参照）。また、過充電、過放電特性を向上させるために、ケイ素と酸素の原子数比を１：ｙ（０＜ｙ＜２）と制御したケイ素酸化物を用いている（例えば、特許文献１３参照）。   Moreover, in order to improve high battery capacity and cycle characteristics, particles having a silicon microcrystalline phase dispersed in silicon dioxide are used (see, for example, Patent Document 12). Further, in order to improve overcharge and overdischarge characteristics, silicon oxide in which the atomic ratio of silicon and oxygen is controlled to 1: y (0 <y <2) is used (for example, see Patent Document 13). .

特開２００１−１８５１２７号公報JP 2001-185127 A 特開２００２−０４２８０６号公報JP 2002-042806 A 特開２００６−１６４９５４号公報JP 2006-164955 A 特開２００６−１１４４５４号公報JP 2006-114454 A 特開２００９−０７０８２５号公報JP 2009-070825 A 特表２０１３−５１３２０６号公報Special table 2013-513206 gazette 特開２００８−２８２８１９号公報JP 2008-282819 A 特開２００８−２５１３６９号公報JP 2008-251369 A 特開２００８−１７７３４６号公報JP 2008-177346 A 特開２００７−２３４２５５号公報JP 2007-234255 A 特開２００９−２１２０７４号公報JP 2009-212074 A 特開２００９−２０５９５０号公報JP 2009-205950 A 特許第２９９７７４１号公報Japanese Patent No. 2999741

上述のように、近年、モバイル端末などに代表される小型の電子機器は高性能化、多機能化がすすめられており、その主電源である非水電解質二次電池、特にリチウムイオン二次電池は電池容量の増加が求められている。この問題を解決する１つの手法として、ケイ素材を主材として用いた負極からなる非水電解質二次電池の開発が望まれている。また、ケイ素材を用いた非水電解質二次電池は炭素材を用いた非水電解質二次電池と同等に近いサイクル特性が望まれている。   As described above, in recent years, small electronic devices typified by mobile terminals and the like have been promoted to have high performance and multiple functions, and non-aqueous electrolyte secondary batteries, particularly lithium ion secondary batteries, which are the main power sources thereof. Is required to increase battery capacity. As one method for solving this problem, development of a non-aqueous electrolyte secondary battery including a negative electrode using a siliceous material as a main material is desired. In addition, non-aqueous electrolyte secondary batteries using a siliceous material are desired to have cycle characteristics close to those of a non-aqueous electrolyte secondary battery using a carbon material.

本発明は、上記問題点に鑑みてなされたものであって、電池容量を増加させ、サイクル特性、電池初期効率を向上させることが可能な非水電解質二次電池用負極活物質を提供することを目的とする。また、本発明は、その負極活物質を用いた非水電解質二次電池を提供することも目的とする。さらに、本発明は、電池容量を増加させ、サイクル特性及び電池初期効率に優れる非水電解質二次電池用負極材を製造する方法を提供することも目的とする。   The present invention has been made in view of the above problems, and provides a negative electrode active material for a non-aqueous electrolyte secondary battery capable of increasing battery capacity and improving cycle characteristics and battery initial efficiency. With the goal. Another object of the present invention is to provide a nonaqueous electrolyte secondary battery using the negative electrode active material. Another object of the present invention is to provide a method for producing a negative electrode material for a non-aqueous electrolyte secondary battery that increases battery capacity and is excellent in cycle characteristics and battery initial efficiency.

上記目的を達成するために、本発明は、負極活物質粒子を有し、該負極活物質粒子はケイ素化合物（ＳｉＯｘ：０．５≦ｘ≦１．６）を含有するものである非水電解質二次電池用負極活物質であって、前記負極活物質粒子は表面の少なくとも一部に炭素被膜を有し、該炭素被膜は、前記炭素被膜を前記負極活物質粒子から単離して測定した多点ＢＥＴ法による比表面積が５ｍ２／ｇ以上１０００ｍ２／ｇ以下であり、かつ、前記炭素被膜は、前記炭素被膜を前記負極活物質粒子から単離して測定した圧縮抵抗率が、１．０ｇ／ｃｍ３の密度に圧縮した時に１．０×１０−３Ω・ｃｍ以上１．０Ω・ｃｍ以下であることを特徴とする非水電解質二次電池用負極活物質を提供する。 In order to achieve the above object, the present invention provides a non-aqueous solution having negative electrode active material particles, the negative electrode active material particles containing a silicon compound (SiO x : 0.5 ≦ x ≦ 1.6). A negative electrode active material for an electrolyte secondary battery, wherein the negative electrode active material particles have a carbon coating on at least a part of a surface thereof, and the carbon coating was measured by isolating the carbon coating from the negative electrode active material particles. The specific surface area by the multipoint BET method is 5 m 2 / g or more and 1000 m 2 / g or less, and the carbon coating film has a compression resistivity of 1. which is measured by isolating the carbon coating film from the negative electrode active material particles. Provided is a negative electrode active material for a non-aqueous electrolyte secondary battery that is 1.0 × 10 −3 Ω · cm to 1.0 Ω · cm when compressed to a density of 0 g / cm 3 .

本発明の負極活物質は、ケイ素化合物を含有する負極活物質粒子を有するので、炭素系活物質粒子を主体として用いた場合より電池容量が格段に大きく、ケイ素化合物を含有する負極活物質粒子の表面の少なくとも一部が炭素被膜で被覆されていることで、優れた導電性を有するものとなる。さらに、この負極活物質粒子から単離した炭素被膜の比表面積が上記のような範囲であれば、電池の電解液の含浸性が良好となる。また、単離した炭素被膜の比表面積が上記のような範囲であれば、この負極活物質粒子の表面に吸着する結着剤の量が適当となり結着性が向上する。また、単離した炭素被膜の圧縮抵抗率が上記のようであれば、負極活物質粒子の表面の導電性が充分となり、かつ、表面の電力集中によるＬｉの微小析出が起こり難い。また、単離した炭素被膜の比表面積及び圧縮抵抗率を測定することで、ケイ素化合物等の影響を除去し、純粋な炭素被膜の特性を測定することが可能となる。このような負極活物質は、負極としたときに高容量であり、さらに、優れた容量維持率及び初回効率を発揮する。以下、本発明における炭素被膜で被覆したケイ素化合物から成る負極活物質粒子を「ケイ素系活物質粒子」とも称する。   Since the negative electrode active material of the present invention has negative electrode active material particles containing a silicon compound, the battery capacity is much larger than when the carbon-based active material particles are mainly used, and the negative electrode active material particles containing a silicon compound By having at least a part of the surface covered with the carbon film, the film has excellent conductivity. Furthermore, when the specific surface area of the carbon coating isolated from the negative electrode active material particles is in the above range, the impregnation property of the battery electrolyte is good. Moreover, if the specific surface area of the isolated carbon film is in the above range, the amount of the binder adsorbed on the surface of the negative electrode active material particles becomes appropriate, and the binding property is improved. Further, if the compression resistivity of the isolated carbon coating is as described above, the surface conductivity of the negative electrode active material particles is sufficient, and Li precipitation due to power concentration on the surface hardly occurs. Further, by measuring the specific surface area and compression resistivity of the isolated carbon film, it is possible to remove the influence of the silicon compound and the like and measure the characteristics of the pure carbon film. Such a negative electrode active material has a high capacity when used as a negative electrode, and further exhibits an excellent capacity retention ratio and initial efficiency. Hereinafter, the negative electrode active material particles made of a silicon compound coated with a carbon coating in the present invention are also referred to as “silicon-based active material particles”.

このとき、前記炭素被膜の真密度が１．２ｇ／ｃｍ３以上１．９ｇ／ｃｍ３以下の範囲であることが好ましい。 At this time, the true density of the carbon coating is preferably in the range of 1.2 g / cm 3 or more and 1.9 g / cm 3 or less.

炭素被膜の真密度が、１．９ｇ／ｃｍ３以下であれば、ケイ素化合物の表面の炭素被膜が緻密になり過ぎないため、内部のケイ素化合物まで電解液が含浸しやすく、サイクル特性や初期充放電特性などの電池特性がより向上する。また、真密度が１．２ｇ／ｃｍ３以上であると、ケイ素化合物を含有する負極活物質粒子の比表面積が適切な値となり、負極を製造する際に結着剤を適切な量だけ吸着して結着剤の効果を向上させ、電池特性がより向上する。 If the true density of the carbon coating is 1.9 g / cm 3 or less, the carbon coating on the surface of the silicon compound will not be too dense, so that the internal silicon compound can be easily impregnated with the electrolyte, and cycle characteristics and initial charge can be improved. Battery characteristics such as discharge characteristics are further improved. Further, when the true density is 1.2 g / cm 3 or more, the specific surface area of the negative electrode active material particles containing the silicon compound becomes an appropriate value, and an appropriate amount of the binder is adsorbed when the negative electrode is manufactured. Thus, the effect of the binder is improved, and the battery characteristics are further improved.

またこのとき、前記炭素被膜は、前記炭素被膜を前記負極活物質粒子から単離し、該単離した炭素被膜を単位面積あたりの質量が０．１５ｇ／ｃｍ２となるように測定容器に仕込んだ後に、５０ＭＰａで加圧して圧縮した場合の圧縮密度が１．０ｇ／ｃｍ３以上１．８ｇ／ｃｍ３以下であることが好ましい。 At this time, the carbon coating was prepared by isolating the carbon coating from the negative electrode active material particles, and charging the isolated carbon coating into a measurement container so that the mass per unit area was 0.15 g / cm 2 . Later, it is preferable that the compression density when compressed by pressing at 50 MPa is 1.0 g / cm 3 or more and 1.8 g / cm 3 or less.

ケイ素系活物質粒子から単離した炭素被膜が、上記の圧縮密度を満たす負極活物質は、負極作成時に導電助剤がケイ素系活物質粒子にまとわりつきやすくなるため、電極内部の導電性を優れたものとすることができる。   The negative electrode active material in which the carbon coating isolated from the silicon-based active material particles satisfies the above-described compression density has excellent conductivity inside the electrode because the conductive auxiliary agent tends to cling to the silicon-based active material particles at the time of preparing the negative electrode. Can be.

このとき、前記炭素被膜の含有率が、前記負極活物質粒子に対し０．１質量％以上２５質量％以下であることが好ましい。   At this time, it is preferable that the content rate of the said carbon film is 0.1 to 25 mass% with respect to the said negative electrode active material particle.

このような割合で炭素被膜を有すれば、高容量のケイ素化合物を含む負極活物質粒子を適切な割合で含むことができ、十分な電池容量を確保することができる。   If it has a carbon film in such a ratio, the negative electrode active material particle containing a high capacity | capacitance silicon compound can be included in a suitable ratio, and sufficient battery capacity can be ensured.

またこのとき、前記炭素被膜が、前記炭素被膜を前記負極活物質粒子から単離して測定した窒素ガスによる吸脱着等温線において、前記吸脱着等温線のＩＵＰＡＣ分類におけるＩＩ型又はＩＩＩ型の特徴を有することが好ましい。   Further, at this time, the carbon coating is characterized by the type II or type III in the IUPAC classification of the adsorption / desorption isotherm in the adsorption / desorption isotherm by nitrogen gas measured by isolating the carbon coating from the negative electrode active material particles. It is preferable to have.

ケイ素系活物質粒子から単離した炭素被膜から測定された吸脱着等温線が、ＩＩ型又はＩＩＩ型であれば、炭素被膜の表面が無孔性であるといえるため、負極を製造する際に結着剤の消費を最小限に抑えることができ、また、結着剤が過剰に吸着しないので、膨張収縮量の大きなケイ素化合物を含有するケイ素系活物質粒子の結着に優れた効果をなすことができる。   When the adsorption / desorption isotherm measured from the carbon coating isolated from the silicon-based active material particles is type II or type III, it can be said that the surface of the carbon coating is nonporous. Binder consumption can be minimized, and since the binder is not excessively adsorbed, it has an excellent effect on binding of silicon-based active material particles containing a silicon compound having a large expansion / contraction amount. be able to.

このとき、前記炭素被膜の単離を、前記負極活物質粒子をフッ化水素酸及び硝酸を含む溶液と反応させることより、前記負極活物質粒子から前記ケイ素化合物を除去することで行うことができる。   At this time, the carbon coating can be isolated by removing the silicon compound from the negative electrode active material particles by reacting the negative electrode active material particles with a solution containing hydrofluoric acid and nitric acid. .

炭素被膜の単離は、具体的にはこのような方法により行うことができる。   Specifically, the carbon film can be isolated by such a method.

またこのとき、前記炭素被膜が、ラマンスペクトル分析により得られたラマンスペクトルにおいて、１３３０ｃｍ−１と１５８０ｃｍ−１に散乱ピークを有し、それらの散乱ピークの強度の比Ｉ１３３０／Ｉ１５８０が０．７＜Ｉ１３３０／Ｉ１５８０＜２．０を満たすことが好ましい。 At this time, the carbon film is in the Raman spectrum obtained by Raman spectrum analysis, have a scattering peak at 1330 cm -1 and 1580 cm -1, a ratio of the intensity of their scattering peak I 1330 / I 1580 is 0. It is preferable that 7 <I 1330 / I 1580 <2.0 is satisfied.

ケイ素系活物質粒子が有する炭素被膜が、上記ピーク強度比を満たすものであれば、炭素被膜に含まれるダイヤモンド構造を有する炭素材とグラファイト構造を有する炭素材の割合を最適化することができる。   As long as the carbon coating of the silicon-based active material particles satisfies the above peak intensity ratio, the ratio of the carbon material having a diamond structure and the carbon material having a graphite structure contained in the carbon coating can be optimized.

このとき、前記炭素被膜が、ＴＯＦ−ＳＩＭＳ（飛行時間型二次イオン質量分析法）によって、ＣｙＨｚ系化合物のフラグメントが検出され、該ＣｙＨｚ系化合物のフラグメントとして、６≧ｙ≧２、２ｙ＋２≧ｚ≧２ｙ−２の範囲を満たすものが少なくとも一部に検出されることが好ましい。 In this case, the carbon film is, the TOF-SIMS (time-of-flight secondary ion mass spectrometry), fragments of C y H z type compounds are detected, as a fragment of the C y H z type compounds, 6 ≧ y It is preferable that at least a part satisfying the range of ≧ 2, 2y + 2 ≧ z ≧ 2y−2 is detected.

ＴＯＦ−ＳＩＭＳによって、ＣｙＨｚ系フラグメントのような化合物フラグメントが検出される表面状態であれば、ＣＭＣ（カルボキシメチルセルロース）やポリイミドなどの負極結着剤との相性がよくなり、より電池特性が向上する。 By TOF-SIMS, as long as the surface condition of Compound fragments such as C y H z type fragment is detected, the better the compatibility with the anode binder such as CMC (carboxymethyl cellulose), polyimide, more battery characteristics improves.

またこのとき、前記炭素被膜で検出されるＣｙＨｚ系化合物のフラグメントが、ＴＯＦ−ＳＩＭＳにおけるＣ４Ｈ９の検出強度ＤとＣ３Ｈ５の検出強度Ｅが２．５≧Ｄ／Ｅ≧０．３の関係を満たすものであることが好ましい。 At this time, the fragment of the C y H z compound detected by the carbon coating has a C 4 H 9 detection intensity D and a C 3 H 5 detection intensity E of 2.5 ≧ D / E in TOF-SIMS. It is preferable that the relationship of ≧ 0.3 is satisfied.

Ｃ４Ｈ９とＣ３Ｈ５の検出強度の比が、上記範囲を満たすものであれば、炭素被膜による導電性向上効果をより効果的なものとすることができる。 If the ratio of the detected intensities of C 4 H 9 and C 3 H 5 satisfies the above range, the conductivity improving effect by the carbon coating can be made more effective.

このとき、前記炭素被膜の平均厚さが５ｎｍ以上５０００ｎｍ以下のものであることが好ましい。   At this time, the average thickness of the carbon coating is preferably 5 nm or more and 5000 nm or less.

炭素被膜がこのような平均厚さを満たすものであれば、十分な導電性を付与できるとともに、ケイ素化合物の割合を高くすることができる。   If the carbon film satisfies such an average thickness, sufficient conductivity can be imparted and the ratio of the silicon compound can be increased.

またこのとき、前記炭素被膜の平均被覆率が３０％以上のものであることが好ましい。   At this time, the average coverage of the carbon coating is preferably 30% or more.

上記の平均被覆率とすることで、このようなケイ素系活物質粒子を含む負極活物質をリチウムイオン二次電池の負極活物質として用いた際に、炭素成分が導電性向上に特に有効に働く。   By using the above average coverage, the carbon component works particularly effectively for improving the conductivity when the negative electrode active material containing such silicon-based active material particles is used as the negative electrode active material of the lithium ion secondary battery. .

このとき、前記炭素被膜が、炭素を含む化合物を熱分解することで得られたものであることが好ましい。   At this time, it is preferable that the carbon film is obtained by pyrolyzing a compound containing carbon.

このような手法で得られた炭素被膜は、ケイ素系活物質粒子の表面において高い平均被覆率を有するものとなる。   The carbon film obtained by such a method has a high average coverage on the surface of the silicon-based active material particles.

またこのとき、前記ケイ素化合物において、２９Ｓｉ−ＭＡＳ−ＮＭＲスペクトルから得られるケミカルシフト値として、−２０〜−７４ｐｐｍで与えられるアモルファスシリコン領域のピーク面積Ａと−７５〜−９４ｐｐｍで与えられる結晶性シリコン領域及びＬｉシリケート領域のピーク面積Ｂと−９５〜−１５０ｐｐｍに与えられるシリカ領域のピーク面積Ｃが式（１）を満たすことが好ましい。
式（１）：５．０≧Ａ／Ｂ≧０．０１、６．０≧（Ａ＋Ｂ）／Ｃ≧０．０２ At this time, in the silicon compound, as the chemical shift value obtained from the 29 Si-MAS-NMR spectrum, the peak area A of the amorphous silicon region given by −20 to −74 ppm and the crystallinity given by −75 to −94 ppm It is preferable that the peak area B of the silicon region and the Li silicate region and the peak area C of the silica region given to −95 to −150 ppm satisfy the formula (1).
Formula (1): 5.0 ≧ A / B ≧ 0.01, 6.0 ≧ (A + B) /C≧0.02

ケイ素系活物質粒子に含まれるケイ素化合物が、２９Ｓｉ−ＭＡＳ−ＮＭＲ スペクトルにおいて、上記式（１）を満たすピーク面積比を有するものであれば、Ｌｉの挿入に伴う膨張が抑えられるアモルファスシリコンの割合が高いため、負極の膨張が抑えられ、より良好なサイクル特性が得られる。また、このようなものであれば、シリコン成分及びＬｉシリケート成分に対してシリカ成分の割合が小さいので、ケイ素化合物内での電子伝導性の低下を抑制できる。 If the silicon compound contained in the silicon-based active material particles has a peak area ratio satisfying the above formula (1) in the 29 Si-MAS-NMR spectrum, the expansion of the amorphous silicon that suppresses the expansion due to the insertion of Li can be reduced. Since the ratio is high, expansion of the negative electrode is suppressed, and better cycle characteristics can be obtained. Moreover, if it is such, since the ratio of a silica component with respect to a silicon component and a Li silicate component is small, the fall of the electronic conductivity in a silicon compound can be suppressed.

このとき、前記負極活物質粒子は、Ｘ線回折により得られるＳｉ（１１１）結晶面に起因する回折ピークの半値幅（２θ）が１．２°以上であると共に、その結晶面に起因する結晶子サイズが７．５ｎｍ以下であることが好ましい。   At this time, the negative electrode active material particles have a half-value width (2θ) of a diffraction peak attributed to the Si (111) crystal plane obtained by X-ray diffraction of 1.2 ° or more and a crystal attributed to the crystal plane. The child size is preferably 7.5 nm or less.

このような半値幅及び結晶子サイズを有するケイ素化合物は、結晶性が低くＳｉ結晶の存在量が少ないため、電池特性を向上させることができる。また、このような結晶性の低いケイ素化合物が存在することで、安定的なＬｉ化合物の生成を行うことができる。   Since the silicon compound having such a half width and crystallite size has low crystallinity and a small amount of Si crystals, the battery characteristics can be improved. In addition, the presence of such a low-crystallinity silicon compound makes it possible to generate a stable Li compound.

またこのとき、前記負極活物質粒子のメディアン径が０．５μｍ以上２０μｍ以下であることが好ましい。   Moreover, it is preferable at this time that the median diameter of the said negative electrode active material particle is 0.5 micrometer or more and 20 micrometers or less.

このようなメディアン径のケイ素系活物質粒子を含む負極活物質であれば、充放電時においてリチウムイオンの吸蔵放出がされやすくなるとともに、ケイ素系活物質粒子が割れにくくなる。その結果、容量維持率を向上させることができる。   If the negative electrode active material includes silicon-based active material particles having such a median diameter, lithium ion is easily occluded and released during charge and discharge, and the silicon-based active material particles are difficult to break. As a result, the capacity maintenance rate can be improved.

このとき、前記負極活物質粒子の少なくとも一部にＬｉを含有することが好ましい。   At this time, it is preferable that at least a part of the negative electrode active material particles contain Li.

負極に含まれるケイ素系活物質粒子に、Ｌｉ化合物が含まれていることにより、初回効率が向上する。また、非水電解質二次電池とした場合の負極の初回効率が上昇するため、サイクル試験時の正極と負極のバランスずれが抑制され、維持率が向上する。   The initial efficiency is improved by including the Li compound in the silicon-based active material particles contained in the negative electrode. In addition, since the initial efficiency of the negative electrode in the case of a nonaqueous electrolyte secondary battery is increased, a deviation in the balance between the positive electrode and the negative electrode during the cycle test is suppressed, and the maintenance ratio is improved.

また、本発明の負極活物質粒子は、前記負極活物質粒子の少なくとも一部に、Ｌｉ２ＳｉＯ３及びＬｉ４ＳｉＯ４のうち少なくとも１種以上を含有することが好ましい。 The negative electrode active material particle of the present invention, at least a portion of the anode active material particles preferably contains at least one or more of Li 2 SiO 3 and Li 4 SiO 4.

ケイ素系活物質粒子が、Ｌｉ化合物として比較的安定している上記のＬｉシリケートを含んでいれば、電極作製時のスラリーに対する安定性がより向上する。   If the silicon-based active material particles contain the above-described Li silicate that is relatively stable as a Li compound, the stability with respect to the slurry during electrode production is further improved.

また、本発明の負極活物質粒子は、前記負極活物質粒子において、２９Ｓｉ−ＭＡＳ−ＮＭＲ スペクトルから得られる、ケミカルシフト値として−７５〜−９４ｐｐｍで与えられる結晶性シリコン領域及びＬｉシリケート領域の最大ピーク強度値Ｈと、ケミカルシフト値として−９５〜−１５０ｐｐｍで与えられるシリカ領域のピーク強度値Ｉが、Ｈ＞Ｉという関係を満たすものであることが好ましい。 Moreover, the negative electrode active material particles of the present invention are the negative electrode active material particles of the crystalline silicon region and Li silicate region, which are obtained from the 29 Si-MAS-NMR spectrum and given as a chemical shift value of −75 to −94 ppm. It is preferable that the maximum peak intensity value H and the peak intensity value I of the silica region given by -95 to -150 ppm as the chemical shift value satisfy the relationship of H> I.

ケイ素系活物質粒子において、シリカ（ＳｉＯ２）成分を基準として結晶性シリコン及びＬｉ２ＳｉＯ３等のＬｉシリケートの量がより多いものであれば、Ｌｉの挿入による電池特性の向上効果を十分に得られる負極活物質となる。 If the silicon-based active material particles have a larger amount of crystalline silicon and Li silicate such as Li 2 SiO 3 based on the silica (SiO 2 ) component, the effect of improving battery characteristics due to insertion of Li will be sufficient. It becomes the negative electrode active material obtained.

また、前記非水電解質二次電池用負極活物質と炭素系活物質との混合物を含む負極電極と対極リチウムとから成る試験セルを作製し、該試験セルにおいて、前記非水電解質二次電池用負極活物質にリチウムを挿入するよう電流を流す充電と、前記非水電解質二次電池用負極活物質からリチウムを脱離するよう電流を流す放電とから成る充放電を３０回実施し、各充放電における放電容量Ｑを前記対極リチウムを基準とする前記負極電極の電位Ｖで微分した微分値ｄＱ／ｄＶと前記電位Ｖとの関係を示すグラフを描いた場合に、Ｘ回目以降（１≦Ｘ≦３０）の放電時における、前記負極電極の電位Ｖが０．４０Ｖ〜０．５５Ｖの範囲にピークを有するものであることが好ましい。   Further, a test cell comprising a negative electrode containing a mixture of the negative electrode active material for a non-aqueous electrolyte secondary battery and a carbon-based active material and counter electrode lithium is prepared, and the test cell is used for the non-aqueous electrolyte secondary battery. Charging / discharging consisting of charging for flowing current to insert lithium into the negative electrode active material and discharging for flowing current to desorb lithium from the negative electrode active material for non-aqueous electrolyte secondary battery was performed 30 times. When a graph showing the relationship between the differential value dQ / dV obtained by differentiating the discharge capacity Q in the discharge with respect to the potential V of the negative electrode with respect to the counter lithium as a reference and the potential V is drawn from the Xth time (1 ≦ X It is preferable that the potential V of the negative electrode has a peak in the range of 0.40 V to 0.55 V during the discharge of ≦ 30.

Ｖ−ｄＱ／ｄＶ曲線における上記のピークはケイ素材のピークと類似しており、より高電位側における放電カーブが鋭く立ち上がるため、電池設計を行う際、容量発現しやすくなる。また、上記ピークが３０回以内の充放電で発現するものであれば、安定したバルクが形成される負極活物質となる。   The above peak in the V-dQ / dV curve is similar to the peak of the siliceous material, and the discharge curve on the higher potential side rises sharply, so that the capacity is easily developed when designing the battery. Moreover, if the said peak expresses by charge / discharge within 30 times, it will become a negative electrode active material in which a stable bulk is formed.

またこのとき、本発明の負極活物質は、さらに、炭素系活物質粒子を含有することが好ましい。   At this time, the negative electrode active material of the present invention preferably further contains carbon-based active material particles.

本発明において、ケイ素系活物質粒子に加え、さらに、炭素系活物質粒子を含有すれば、負極の容量を増やしつつ、より良好なサイクル特性及び初期充放電特性が得られる。   In the present invention, if carbon-based active material particles are further contained in addition to silicon-based active material particles, better cycle characteristics and initial charge / discharge characteristics can be obtained while increasing the capacity of the negative electrode.

このとき、前記負極活物質粒子と前記炭素系活物質粒子の合計の質量に対する、前記負極活物質粒子の質量の割合が５質量％以上であることが好ましい。   At this time, the ratio of the mass of the negative electrode active material particles to the total mass of the negative electrode active material particles and the carbon-based active material particles is preferably 5% by mass or more.

ケイ素化合物を含む負極活物質粒子の割合が上記のようなものであれば、より電池容量を増加させることができる。   If the ratio of the negative electrode active material particles containing a silicon compound is as described above, the battery capacity can be further increased.

またこのとき、前記負極活物質粒子の平均粒径Ｆが、前記炭素系活物質粒子の平均粒径Ｇに対し、２５≧Ｇ／Ｆ≧０．５の関係を満たすことが好ましい。   At this time, it is preferable that the average particle size F of the negative electrode active material particles satisfies the relationship of 25 ≧ G / F ≧ 0.5 with respect to the average particle size G of the carbon-based active material particles.

炭素系活物質粒子の平均粒径Ｇとケイ素化合物を含む負極活物質粒子の平均粒径Ｆが上記のような関係を満たすことで、合材層の破壊を防止することができる。また、炭素系活物質粒子がケイ素化合物を含む負極活物質粒子に対して大きくなると、充電時の負極体積密度、初期効率が向上し、電池エネルギー密度が向上する。   When the average particle diameter G of the carbon-based active material particles and the average particle diameter F of the negative electrode active material particles containing the silicon compound satisfy the relationship as described above, the destruction of the composite material layer can be prevented. Further, when the carbon-based active material particles are larger than the negative electrode active material particles containing a silicon compound, the negative electrode volume density and initial efficiency during charging are improved, and the battery energy density is improved.

このとき、前記炭素系活物質粒子は黒鉛材料であることが好ましい。   At this time, the carbon-based active material particles are preferably a graphite material.

黒鉛材料は、他の炭素系活物質よりも良好な初回効率、容量維持率を発揮することができるため好適である。   The graphite material is preferable because it can exhibit better initial efficiency and capacity retention than other carbon-based active materials.

また、上記目的を達成するために、本発明は、上記の非水電解質二次電池用負極活物質を含む負極活物質層と、負極集電体とを有し、前記負極活物質層は前記負極集電体上に形成されており、前記負極集電体は炭素及び硫黄を含むとともに、それらの含有量がいずれも１００質量ｐｐｍ以下であることを特徴とする非水電解質二次電池用負極を提供する。   In order to achieve the above object, the present invention includes a negative electrode active material layer containing the negative electrode active material for a non-aqueous electrolyte secondary battery, and a negative electrode current collector, A negative electrode for a non-aqueous electrolyte secondary battery, wherein the negative electrode current collector is formed on a negative electrode current collector, and the negative electrode current collector contains carbon and sulfur, both of which are 100 ppm by mass or less. I will provide a.

このように、負極電極を構成する負極集電体が、炭素及び硫黄を上記のような量で含むことで、充電時の負極電極の変形を抑制することができる。   As described above, the negative electrode current collector constituting the negative electrode includes carbon and sulfur in the above amounts, whereby deformation of the negative electrode during charging can be suppressed.

また、上記目的を達成するために、本発明は、上記の非水電解質二次電池用負極活物質を含むことを特徴とする非水電解質二次電池を提供する。   Moreover, in order to achieve the said objective, this invention provides the nonaqueous electrolyte secondary battery characterized by including said negative electrode active material for nonaqueous electrolyte secondary batteries.

本発明の負極活物質を用いた非水電解質二次電池であれば、高容量であるとともに良好なサイクル特性及び初期充放電特性を有するものとなる。   The nonaqueous electrolyte secondary battery using the negative electrode active material of the present invention has a high capacity and good cycle characteristics and initial charge / discharge characteristics.

また、上記目的を達成するために、本発明は、負極活物質粒子を含む非水電解質二次電池用負極材の製造方法であって、ＳｉＯｘ（０．５≦ｘ≦１．６）で表されるケイ素化合物の粒子を作製する工程と、前記ケイ素化合物の粒子の表面の少なくとも一部を炭素被膜で被覆する工程と、前記炭素被膜が被覆されたケイ素化合物の粒子から、前記炭素被膜を単離して測定した多点ＢＥＴ法による比表面積が５ｍ２／ｇ以上１０００ｍ２／ｇ以下であり、かつ、前記炭素被膜が被覆されたケイ素化合物の粒子から、前記炭素被膜を単離して測定した圧縮抵抗率が、１．０ｇ／ｃｍ３の密度に圧縮した時に１．０×１０−３Ω・ｃｍ以上１．０Ω・ｃｍ以下である前記炭素被膜が被覆されたケイ素化合物の粒子を選別する工程を有し、該選別した前記炭素被膜が被覆されたケイ素化合物の粒子を負極活物質粒子として、非水電解質二次電池用負極材を製造することを特徴とする非水電解質二次電池用負極材の製造方法を提供する。 In order to achieve the above object, the present invention provides a method for producing a negative electrode material for a non-aqueous electrolyte secondary battery including negative electrode active material particles, wherein SiO x (0.5 ≦ x ≦ 1.6) The step of producing particles of the silicon compound represented, the step of coating at least a part of the surface of the particles of the silicon compound with a carbon coating, and the particles of the silicon compound coated with the carbon coating, The carbon film was isolated and measured from silicon compound particles having a specific surface area of 5 m 2 / g or more and 1000 m 2 / g or less as measured by the multi-point BET method, which was isolated and measured. The silicon compound particles coated with the carbon coating having a compression resistivity of 1.0 × 10 −3 Ω · cm to 1.0 Ω · cm when compressed to a density of 1.0 g / cm 3 are selected. And having a process A negative electrode material for a non-aqueous electrolyte secondary battery is manufactured using the silicon compound particles coated with the carbon coating as negative electrode active material particles. .

このような製造方法であれば、上記のように選別した炭素被膜が被覆されたケイ素化合物の粒子を負極活物質粒子として使用することで、高容量であるとともに優れた容量維持率および初回効率を発揮する非水電解質二次電池用負極材を製造することができる。   With such a manufacturing method, by using the silicon compound particles coated with the carbon coating selected as described above as the negative electrode active material particles, a high capacity and an excellent capacity retention rate and initial efficiency are obtained. A negative electrode material for a non-aqueous electrolyte secondary battery can be produced.

本発明の負極活物質は、非水電解質二次電池の負極活物質として用いた際に、高容量で良好なサイクル特性及び初期充放電特性が得られる。また、本発明の非水電解質二次電池用負極活物質を含む二次電池においても同様の特性を得ることができる。また、本発明の二次電池を用いた電子機器、電動工具、電気自動車及び電力貯蔵システム等でも同様の効果を得ることができる。   When the negative electrode active material of the present invention is used as a negative electrode active material for a non-aqueous electrolyte secondary battery, a high capacity and good cycle characteristics and initial charge / discharge characteristics can be obtained. Moreover, the same characteristic can be acquired also in the secondary battery containing the negative electrode active material for nonaqueous electrolyte secondary batteries of this invention. Moreover, the same effect can be acquired also in the electronic device, electric tool, electric vehicle, electric power storage system, etc. which used the secondary battery of this invention.

また、本発明の負極材の製造方法であれば、高容量で良好なサイクル特性及び初期充放電特性を有する非水電解質二次電池用負極材を製造することができる。   Moreover, if it is the manufacturing method of the negative electrode material of this invention, the negative electrode material for nonaqueous electrolyte secondary batteries which has a high capacity | capacitance and favorable cycling characteristics and initial stage charge / discharge characteristics can be manufactured.

本発明の非水電解質二次電池用負極活物質を用いた負極の概略断面図である。It is a schematic sectional drawing of the negative electrode using the negative electrode active material for nonaqueous electrolyte secondary batteries of this invention. 本発明における負極活物質粒子の炭素被膜の密度を求めるためのプロット図である。It is a plot figure for calculating | requiring the density of the carbon film of the negative electrode active material particle in this invention. 本発明の非水電解質二次電池（ラミネートフィルム型リチウムイオン二次電池）の構成の一例を示す分解図である。It is an exploded view which shows an example of a structure of the nonaqueous electrolyte secondary battery (laminated film type lithium ion secondary battery) of this invention.

以下、本発明について実施の形態を説明するが、本発明はこれに限定されるものではない。   Hereinafter, although an embodiment is described about the present invention, the present invention is not limited to this.

前述のように、非水電解質二次電池の電池容量を増加させる１つの手法として、ケイ素材を主材として用いた負極を非水電解質二次電池の負極として用いることが検討されている。   As described above, as one method for increasing the battery capacity of a non-aqueous electrolyte secondary battery, it has been studied to use a negative electrode using a siliceous material as a main material as a negative electrode of a non-aqueous electrolyte secondary battery.

このケイ素材を用いた非水電解質二次電池には、炭素材を用いた非水電解質二次電池と同等に近いサイクル特性が望まれているが、炭素材を用いた非水電解質二次電池と同等のサイクル安定性を示す負極材は提案されていなかった。また、特に酸素を含むケイ素化合物は、炭素材と比較し初回効率が低いため、その分電池容量の向上は限定的であった。   The non-aqueous electrolyte secondary battery using this siliceous material is expected to have cycle characteristics similar to those of the non-aqueous electrolyte secondary battery using the carbon material, but the non-aqueous electrolyte secondary battery using the carbon material is desired. No negative electrode material having a cycle stability equivalent to that of the above has been proposed. In particular, the silicon compound containing oxygen has a lower initial efficiency than the carbon material, so that the battery capacity has been limited to that extent.

そこで、本発明者等は、非水電解質二次電池の負極に用いた際に、良好なサイクル特性及び初回効率が得られる負極活物質について鋭意検討を重ね、本発明に至った。   Accordingly, the present inventors have conducted intensive studies on a negative electrode active material that can provide good cycle characteristics and initial efficiency when used in a negative electrode of a non-aqueous electrolyte secondary battery, leading to the present invention.

本発明の非水電解質二次電池用負極活物質は負極活物質粒子を含んでいる。そして、負極活物質粒子はケイ素化合物（ＳｉＯｘ：０．５≦ｘ≦１．６）を含有するケイ素系活物質粒子である。そして、このケイ素系活物質粒子は、表面の少なくとも一部に炭素被膜を有する。さらに、炭素被膜は、ケイ素系活物質粒子から単離して測定した多点ＢＥＴ法による比表面積が５ｍ２／ｇ以上１０００ｍ２／ｇ以下であり、かつ、ケイ素系活物質粒子から単離して測定した圧縮抵抗率が、１．０ｇ／ｃｍ３の密度に圧縮した時に１．０×１０−３Ω・ｃｍ以上１．０Ω・ｃｍ以下である。 The negative electrode active material for a nonaqueous electrolyte secondary battery of the present invention includes negative electrode active material particles. The negative electrode active material particles are silicon-based active material particles containing a silicon compound (SiO x : 0.5 ≦ x ≦ 1.6). The silicon-based active material particles have a carbon coating on at least a part of the surface. Further, the carbon coating has a specific surface area of 5 m 2 / g or more and 1000 m 2 / g or less by a multi-point BET method measured by isolation from the silicon active material particles, and is isolated from the silicon active material particles and measured. The compressed resistivity is 1.0 × 10 −3 Ω · cm to 1.0 Ω · cm when compressed to a density of 1.0 g / cm 3 .

本発明の負極活物質は、ケイ素系活物質粒子を有するので、電池容量が大きく、ケイ素系活物質粒子の表面の少なくとも一部が炭素被膜で被覆されていることで、優れた導電性を有するものとなる。   Since the negative electrode active material of the present invention has silicon-based active material particles, the battery capacity is large, and at least a part of the surface of the silicon-based active material particles is coated with a carbon film, thereby having excellent conductivity. It will be a thing.

また、ケイ素系活物質粒子から炭素被膜を単離して測定した多点ＢＥＴ法による比表面積が、５ｍ２／ｇを下回る場合は、電解液の含浸性が悪く、サイクル特性や初回充放電特性などの電池特性が悪化する。また、ケイ素系活物質粒子から単離した炭素被膜の比表面積が１０００ｍ２／ｇを上回る場合は、負極活物質をスラリーにした場合の塗工性が悪化する。また、ケイ素系活物質粒子から単離した炭素被膜を１．０ｇ／ｃｍ３の密度に圧縮した時に測定した圧縮抵抗率が、１．０Ω・ｃｍを超える場合、ケイ素系活物質粒子の表面の導電性が不足し、サイクル特性や初期充放電特性などの電池特性が悪化する。また、上記圧縮抵抗率が１．０×１０−３Ω・ｃｍ未満であると、ケイ素系活物質粒子の表面で電流集中が起こりやすく、電池の充放電時にＬｉの微小析出が発生し、電池特性が悪化する。 Moreover, when the specific surface area by the multipoint BET method measured by isolating the carbon film from the silicon-based active material particles is less than 5 m 2 / g, the impregnation property of the electrolytic solution is poor, and cycle characteristics, initial charge / discharge characteristics, etc. The battery characteristics deteriorate. Moreover, when the specific surface area of the carbon film isolated from the silicon-based active material particles exceeds 1000 m 2 / g, the coatability when the negative electrode active material is made into a slurry is deteriorated. Further, when the compression resistivity measured when the carbon coating isolated from the silicon-based active material particles is compressed to a density of 1.0 g / cm 3 exceeds 1.0 Ω · cm, the surface of the silicon-based active material particles Conductivity is insufficient, and battery characteristics such as cycle characteristics and initial charge / discharge characteristics are deteriorated. Further, when the compression resistivity is less than 1.0 × 10 −3 Ω · cm, current concentration is likely to occur on the surface of the silicon-based active material particles, and Li precipitation occurs during charging / discharging of the battery. Characteristics deteriorate.

それに対し、本発明の負極活物質は、炭素被膜をケイ素系活物質粒子から単離して測定した多点ＢＥＴ法による比表面積が５ｍ２／ｇ以上１０００ｍ２／ｇ以下であり、かつ、炭素被膜をケイ素系活物質粒子から単離して測定した圧縮抵抗率が、１．０ｇ／ｃｍ３の密度に圧縮した時に１．０×１０−３Ω・ｃｍ以上１．０Ω・ｃｍ以下であるので、二次電池に使用した場合、上記した電池特性の悪化が発生しづらく、高電池容量、良好なサイクル特性及び初回充放電特性が得られる。 On the other hand, the negative electrode active material of the present invention has a specific surface area of 5 m 2 / g or more and 1000 m 2 / g or less according to the multipoint BET method measured by isolating the carbon film from the silicon-based active material particles, and the carbon film Since the compression resistivity measured by isolating from the silicon-based active material particles is 1.0 × 10 −3 Ω · cm to 1.0 Ω · cm when compressed to a density of 1.0 g / cm 3 , When used in a secondary battery, the above-described deterioration of battery characteristics is unlikely to occur, and high battery capacity, good cycle characteristics, and initial charge / discharge characteristics can be obtained.

＜１．非水電解質二次電池用負極＞
本発明の非水電解質二次電池用負極材を用いた非水電解質二次電池用負極について説明する。図１は、本発明の一実施形態における非水電解質二次電池用負極（以下、単に「負極」と称することがある。）の断面構成を表している。 <1. Negative electrode for non-aqueous electrolyte secondary battery>
The negative electrode for nonaqueous electrolyte secondary batteries using the negative electrode material for nonaqueous electrolyte secondary batteries of the present invention will be described. FIG. 1 shows a cross-sectional configuration of a negative electrode for a nonaqueous electrolyte secondary battery (hereinafter sometimes simply referred to as “negative electrode”) according to an embodiment of the present invention.

［負極の構成］
図１に示したように、負極１０は、負極集電体１１の上に負極活物質層１２を有する構成になっている。この負極活物質層１２は負極集電体１１の両面、又は、片面だけに設けられていても良い。さらに、本発明の負極活物質が用いられたものであれば、負極集電体１１はなくてもよい。 [Configuration of negative electrode]
As shown in FIG. 1, the negative electrode 10 is configured to have a negative electrode active material layer 12 on a negative electrode current collector 11. The negative electrode active material layer 12 may be provided on both surfaces or only one surface of the negative electrode current collector 11. Furthermore, the negative electrode current collector 11 may be omitted as long as the negative electrode active material of the present invention is used.

［負極集電体］
負極集電体１１は、優れた導電性材料であり、かつ、機械的な強度に長けた物で構成される。負極集電体１１に用いることができる導電性材料として、例えば銅（Ｃｕ）やニッケル（Ｎｉ）があげられる。この導電性材料は、リチウム（Ｌｉ）と金属間化合物を形成しない材料であることが好ましい。 [Negative electrode current collector]
The negative electrode current collector 11 is an excellent conductive material and is made of a material that is excellent in mechanical strength. Examples of the conductive material that can be used for the negative electrode current collector 11 include copper (Cu) and nickel (Ni). This conductive material is preferably a material that does not form an intermetallic compound with lithium (Li).

負極集電体１１は、主元素以外に炭素（Ｃ）や硫黄（Ｓ）を含んでいることが好ましい。負極集電体の物理的強度が向上するためである。特に、充電時に膨張する活物質層を有する場合、集電体が上記の元素を含んでいれば、集電体を含む電極変形を抑制する効果があるからである。上記の炭素及び硫黄の含有量は、特に限定されないが、中でも、それぞれ１００質量ｐｐｍ以下であることが好ましい。より高い変形抑制効果が得られるからである。   The negative electrode current collector 11 preferably contains carbon (C) or sulfur (S) in addition to the main element. This is because the physical strength of the negative electrode current collector is improved. In particular, in the case of having an active material layer that expands during charging, if the current collector contains the above-described element, there is an effect of suppressing electrode deformation including the current collector. Although content of said carbon and sulfur is not specifically limited, Especially, it is preferable that it is 100 mass ppm or less, respectively. This is because a higher deformation suppressing effect can be obtained.

負極集電体１１の表面は、粗化されていても、粗化されていなくても良い。粗化されている負極集電体は、例えば、電解処理、エンボス処理、又は化学エッチングされた金属箔などである。粗化されていない負極集電体は例えば、圧延金属箔などである。   The surface of the negative electrode current collector 11 may be roughened or not roughened. The roughened negative electrode current collector is, for example, a metal foil subjected to electrolytic treatment, embossing treatment, or chemical etching. The non-roughened negative electrode current collector is, for example, a rolled metal foil.

［負極活物質層］
負極活物質層１２は、本発明の負極活物質を含んでおり、電池設計上、さらに負極結着剤や負極導電助剤など、他の材料を含んでいても良い。負極活物質として、ケイ素化合物（ＳｉＯｘ：０．５≦ｘ≦１．６）を含有する負極活物質粒子（ケイ素系活物質粒子）の他に炭素系活物質なども含んでいても良い。本発明の非水電解質二次電池用負極活物質は、この負極活物質層１２を構成する材料となる。 [Negative electrode active material layer]
The negative electrode active material layer 12 includes the negative electrode active material of the present invention, and may further include other materials such as a negative electrode binder and a negative electrode conductive additive in battery design. As the negative electrode active material, in addition to the negative electrode active material particles (silicon-based active material particles) containing a silicon compound (SiO x : 0.5 ≦ x ≦ 1.6), a carbon-based active material or the like may also be included. The negative electrode active material for a nonaqueous electrolyte secondary battery of the present invention is a material constituting the negative electrode active material layer 12.

本発明の負極活物質に含まれるケイ素系活物質粒子はリチウムイオンを吸蔵、放出可能なケイ素化合物を含有している。   The silicon-based active material particles contained in the negative electrode active material of the present invention contain a silicon compound that can occlude and release lithium ions.

上記のように本発明の負極活物質が含有するケイ素系活物質粒子はケイ素化合物（ＳｉＯｘ：０．５≦ｘ≦１．６）を含む。ケイ素化合物の組成としてはｘが１に近い方が好ましい。これは、高いサイクル特性が得られるからである。また、本発明におけるケイ素材組成は必ずしも純度１００％を意味しているわけではなく、微量の不純物元素を含んでいても良い。 As described above, the silicon-based active material particles contained in the negative electrode active material of the present invention contain a silicon compound (SiO x : 0.5 ≦ x ≦ 1.6). As the composition of the silicon compound, x is preferably close to 1. This is because high cycle characteristics can be obtained. Moreover, the siliceous material composition in the present invention does not necessarily mean 100% purity, and may contain a trace amount of impurity elements.

また、上述のように、本発明の負極活物質に含まれるケイ素系活物質粒子は、表面の少なくとも一部が炭素被膜で被覆されている。そして、上述のように、炭素被膜は炭素被膜をケイ素系活物質粒子から単離して測定した多点ＢＥＴ法による比表面積が５ｍ２／ｇ以上１０００ｍ２／ｇ以下であり、かつ、炭素被膜をケイ素系活物質粒子から単離して測定した圧縮抵抗率が、１．０ｇ／ｃｍ３の密度に圧縮した時に１．０×１０−３Ω・ｃｍ以上１．０Ω・ｃｍ以下である。 In addition, as described above, at least a part of the surface of the silicon-based active material particles contained in the negative electrode active material of the present invention is covered with the carbon film. As described above, the carbon coating has a specific surface area of 5 m 2 / g or more and 1000 m 2 / g or less according to the multipoint BET method measured by isolating the carbon coating from the silicon-based active material particles and measuring the carbon coating. The compression resistivity measured by isolation from the silicon-based active material particles is 1.0 × 10 −3 Ω · cm or more and 1.0 Ω · cm or less when compressed to a density of 1.0 g / cm 3 .

このとき、炭素被膜は、炭素被膜をケイ素系活物質粒子から単離し、単離した炭素被膜を単位面積あたりの質量が０．１５ｇ／ｃｍ２となるように測定容器に仕込んだ後に、５０ＭＰａで加圧して圧縮した場合の圧縮密度が１．０ｇ／ｃｍ３以上１．８ｇ／ｃｍ３以下であることが好ましい。ケイ素系活物質粒子から単離した炭素被膜が、上記の圧縮密度を満たす場合、負極作成時に導電助剤がケイ素系活物質粒子にまとわりつきやすくなり結着剤の吸着量が適切な量となるため、電極内部の導電性を優れたものとすることができる。 At this time, the carbon coating was isolated from the silicon-based active material particles, and after the charged carbon coating was charged in a measurement container so that the mass per unit area was 0.15 g / cm 2 , the carbon coating was 50 MPa. The compression density when compressed by pressing is preferably 1.0 g / cm 3 or more and 1.8 g / cm 3 or less. When the carbon coating isolated from the silicon-based active material particles satisfies the above-mentioned compression density, the conductive auxiliary agent tends to cling to the silicon-based active material particles at the time of preparing the negative electrode, and the amount of binder adsorbed becomes an appropriate amount. The electrical conductivity inside the electrode can be made excellent.

また、炭素被膜が、炭素被膜をケイ素系活物質粒子から単離して測定した窒素ガスによる吸脱着等温線において、吸脱着等温線のＩＵＰＡＣ分類におけるＩＩ型又はＩＩＩ型の特徴を有することが好ましい。炭素被膜を単離して測定した吸脱着等温線が、ＩＩ型又はＩＩＩ型であれば、炭素被膜の表面が無孔性であるため、本発明の負極活物質を用いて負極を製造する際に、結着剤の消費を最小限に抑えることができる。さらに、負極活物質の表面に結着剤が過剰に吸着しないので、膨張収縮量の大きなケイ素系活物質粒子を含む負極活物質を適切に結着できる。   Moreover, it is preferable that the carbon coating has the characteristics of type II or type III in the IUPAC classification of the adsorption / desorption isotherm in the adsorption / desorption isotherm by nitrogen gas measured by isolating the carbon coating from the silicon-based active material particles. If the adsorption / desorption isotherm measured by isolating the carbon coating is type II or type III, the surface of the carbon coating is non-porous. Therefore, when the negative electrode is produced using the negative electrode active material of the present invention, , Binder consumption can be minimized. Furthermore, since the binder is not excessively adsorbed on the surface of the negative electrode active material, the negative electrode active material containing silicon-based active material particles having a large expansion / contraction amount can be appropriately bound.

ケイ素系活物質粒子から炭素被膜を単離する方法は、例えば以下の単離方法を使用できる。まず、テフロン（登録商標）製ビーカーに、炭素被膜を有するケイ素系活物質粒子を加え、さらにイオン交換水、エタノールを加えて、テフロン（登録商標）製撹拌棒でよく撹拌する。その後、フッ化水素酸を加えて撹拌し、硝酸を加え、適時イオン交換水を追加し、さらに硝酸を加えて３時間放置する。その後、得られた黒色溶液をろ過することで、単離した炭素被膜をろ取する。その後、単離した炭素被膜を水で洗浄し、さらにエタノールで洗浄後、２００℃で１０時間真空乾燥する。このようにして得られた、単離した炭素被膜を測定対象として、Ｘ線回折及びラマン分光法等の各種分析を行うことができる。そして、単離した炭素被膜に対して各種分析を行うことで、芯材のケイ素化合物等の影響を除去し、純粋な炭素被膜の特性を測定することが可能となる。   As a method for isolating the carbon film from the silicon-based active material particles, for example, the following isolation method can be used. First, silicon-based active material particles having a carbon coating are added to a Teflon (registered trademark) beaker, ion-exchanged water and ethanol are further added, and the mixture is thoroughly stirred with a Teflon (registered trademark) stirring rod. Thereafter, hydrofluoric acid is added and stirred, nitric acid is added, ion-exchanged water is added as appropriate, nitric acid is further added, and the mixture is allowed to stand for 3 hours. Then, the isolated carbon film is filtered by filtering the obtained black solution. Thereafter, the isolated carbon film is washed with water, further washed with ethanol, and then vacuum-dried at 200 ° C. for 10 hours. Various analyzes such as X-ray diffraction and Raman spectroscopy can be performed on the isolated carbon film thus obtained as a measurement target. And by performing various analyzes with respect to the isolated carbon film, it becomes possible to remove the influence of the silicon compound etc. of a core material, and to measure the characteristic of a pure carbon film.

ケイ素系活物質粒子から単離した炭素被膜の比表面積は、多点ＢＥＴ法を用い、吸着等温線の相関係数Ｒ＞０．９９となる４点以上の外挿から得ることができる。   The specific surface area of the carbon film isolated from the silicon-based active material particles can be obtained by extrapolation of four or more points where the correlation coefficient R> 0.99 of the adsorption isotherm using the multipoint BET method.

ケイ素系活物質粒子から単離した炭素被膜の圧縮抵抗率は、例えば下記条件で測定を行うことができる。
・装置：三菱化学アナリテック製 粉体抵抗測定システム ＭＣＰ−ＰＤ型
・４探針法
・仕込み：０．３０ｇ
・加圧・測定：２０Ｎまで加圧、５Ｎごとに粉体抵抗を測定し、得られた測定値を外挿し、１．０ｇ／ｃｍ３時の圧縮抵抗率を算出。 The compression resistivity of the carbon film isolated from the silicon-based active material particles can be measured, for example, under the following conditions.
・ Equipment: Powder resistance measurement system MCP-PD manufactured by Mitsubishi Chemical Analytech ・ 4-probe method ・ Preparation: 0.30 g
And pressure Measurement: 20 N up to pressure, measured powder resistance per 5N, extrapolating measurements obtained, calculated compression resistance of at 1.0 g / cm 3.

また、吸脱着等温線は、吸着剤（ここでは、ケイ素系活物質粒子）に、吸着分子として窒素を吸脱着させることにより測定することができる。測定装置としては、日本ベル株式会社製ＢＥＬＳＯＲＰ−ｍｉｎｉを用いることができる。なお、窒素の吸脱着時の履歴（ヒステリシス）がある場合、吸着・脱着時の同じ圧力での窒素の吸着量の最大履歴差ΔＶが、ｐ／ｐ０＝０．９の場合の窒素の吸着量Ｖと比較し、ΔＶ／Ｖ≦０．０５であれば、履歴は測定誤差によるものとし、実質的に履歴がないものとして、吸脱着等温線をＩＩ型又はＩＩＩ型と分類することができる。ここで、ｐ／ｐ０は相対圧力であり、平衡圧力を飽和蒸気圧で割ったものである。 The adsorption / desorption isotherm can be measured by adsorbing / desorbing nitrogen as an adsorbed molecule on an adsorbent (here, silicon-based active material particles). As a measuring device, BELSORP-mini manufactured by Nippon Bell Co., Ltd. can be used. When there is a history (hysteresis) of nitrogen adsorption / desorption, nitrogen adsorption when the maximum history difference ΔV of nitrogen adsorption amount at the same pressure during adsorption / desorption is p / p 0 = 0.9. If ΔV / V ≦ 0.05 compared with the amount V, the history is due to measurement error, and the adsorption / desorption isotherm can be classified as type II or type III, assuming that there is substantially no history. . Here, p / p 0 is the relative pressure, which is the equilibrium pressure divided by the saturated vapor pressure.

吸着等温線型に分類が異なるケイ素系活物質粒子を分別する方法として、例えばＩＩ型とＩＶ型の分類を有するケイ素系活物質粒子を分別する場合は、まず、ケイ素系活物質粒子の粉体を湿度８０％の環境で１０時間放置（途中で３回以上撹拌）する。次に、円筒容器中に、粉体を円筒容器内の空間に対し嵩密度で５％となるように充填し、円筒容器を２時間撹拌後、円筒容器を立て、静置して粉体が堆積するまで静置する操作を２回繰り返す。得られた粉体のうち、上に堆積した２０％分（ＩＩ型）と、下に堆積した２０％分（ＩＶ型）をそれぞれ分取することで、ＩＩ型とＩＶ型を分別することができる。   As a method for separating silicon-based active material particles having different classifications into adsorption isotherms, for example, when separating silicon-based active material particles having types II and IV, first, powder of silicon-based active material particles is used. Leave in an 80% humidity environment for 10 hours (stir 3 or more times in the middle). Next, the powder is filled in the cylindrical container so that the bulk density is 5% with respect to the space in the cylindrical container, and after stirring the cylindrical container for 2 hours, the cylindrical container is set up and allowed to stand. The operation of allowing to stand until deposition is repeated twice. In the obtained powder, 20% (type II) deposited on the top and 20% (type IV) deposited on the bottom can be separated, respectively, to separate type II and type IV. it can.

また、本発明において、ケイ素系活物質粒子表面の炭素被膜の真密度が１．２ｇ／ｃｍ３以上１．９ｇ／ｃｍ３以下の範囲であることが好ましい。炭素被膜の真密度が、１．９ｇ／ｃｍ３以下であれば、ケイ素系活物質粒子の表面の炭素被膜が緻密になり過ぎないため、ケイ素系活物質粒子に含まれるケイ素化合物に電解液が含浸しやすく、サイクル特性や初期充放電特性などの電池特性が向上する。また、真密度が１．２ｇ／ｃｍ３以上であると、ケイ素系活物質粒子の比表面積が適切な値となり、負極を製造する際に結着剤を適切な量だけ吸着して結着剤の効果を向上させ、電池特性が向上する。 In the present invention, the true density of the carbon coating on the surface of the silicon-based active material particles is preferably in the range of 1.2 g / cm 3 or more and 1.9 g / cm 3 or less. If the true density of the carbon coating is 1.9 g / cm 3 or less, the carbon coating on the surface of the silicon-based active material particles does not become too dense, so that the electrolyte is contained in the silicon compound contained in the silicon-based active material particles. Impregnation is easy and battery characteristics such as cycle characteristics and initial charge / discharge characteristics are improved. In addition, when the true density is 1.2 g / cm 3 or more, the specific surface area of the silicon-based active material particles becomes an appropriate value, and the binder is adsorbed by an appropriate amount when the negative electrode is produced. This improves the battery characteristics.

ここで、ケイ素系活物質粒子の表面に形成された炭素被膜の真密度は、例えば、図２に示すように、炭素被膜の含有率（質量％）とケイ素系活物質粒子の密度とのプロットを数か所作成し、線形近似で炭素被膜の含有率が１００質量％となる点の外挿を行い、炭素被膜のみの真密度を算出することで求めることができる。すなわち、ここで測定される炭素被膜の真密度は、単離して測定されるものではない。   Here, the true density of the carbon film formed on the surface of the silicon-based active material particles is, for example, a plot of the carbon film content (% by mass) and the density of the silicon-based active material particles as shown in FIG. Can be obtained by calculating the true density of only the carbon film by performing extrapolation at a point where the content of the carbon film is 100% by mass by linear approximation. That is, the true density of the carbon film measured here is not measured by isolation.

また、本発明において、ケイ素系活物質粒子の表面に形成された炭素被膜が、ラマンスペクトル分析により得られたラマンスペクトルにおいて、１３３０ｃｍ−１と１５８０ｃｍ−１に散乱ピークを有し、それらの散乱ピークの強度の比Ｉ１３３０／Ｉ１５８０が０．７＜Ｉ１３３０／Ｉ１５８０＜２．０を満たすことが好ましい。これにより、炭素被膜に含まれるダイヤモンド構造を有する炭素材とグラファイト構造を有する炭素材の割合を最適化することができる。その結果、上記の炭素被膜を有するケイ素系活物質粒子を含む負極活物質を非水電解質二次電池の負極として用いた場合、電池特性が良好な非水電解質二次電池を得ることができる。 Further, in the present invention, the silicon-based active material carbon coating formed on the surface of the particles, in the Raman spectrum obtained by Raman spectrum analysis, have a scattering peak at 1330 cm -1 and 1580 cm -1, their scattering peaks It is preferable that the intensity ratio I 1330 / I 1580 satisfies 0.7 <I 1330 / I 1580 <2.0. Thereby, the ratio of the carbon material having a diamond structure and the carbon material having a graphite structure contained in the carbon film can be optimized. As a result, when the negative electrode active material including the silicon-based active material particles having the carbon coating is used as the negative electrode of the nonaqueous electrolyte secondary battery, a nonaqueous electrolyte secondary battery having good battery characteristics can be obtained.

また、ラマンスペクトルは、顕微ラマン分析（即ち、ラマンスペクトル分析）で得ることができ、得られたラマンスペクトルにより、ダイヤモンド構造を有する炭素成分とグラファイト構造を有する炭素成分の割合を求めることができる。即ち、ダイヤモンドはラマンシフトが１３３０ｃｍ−１、グラファイトはラマンシフトが１５８０ｃｍ−１に鋭いピークを示し、その強度比により簡易的にダイヤモンド構造を有する炭素成分とグラファイト構造を有する炭素成分の割合を求めることができる。ダイヤモンドは高強度、高密度、高絶縁性であり、グラファイトは電気伝導性に優れている。そのため、上記のピーク強度比を満たす炭素被膜は、上記のそれぞれの特徴が最適化され、結果として充放電時に伴う電極材料の膨張・収縮による電極破壊を防止でき、かつ導電ネットワークを有する負極活物質となる。 Further, the Raman spectrum can be obtained by microscopic Raman analysis (that is, Raman spectrum analysis), and the ratio of the carbon component having a diamond structure and the carbon component having a graphite structure can be obtained from the obtained Raman spectrum. That is, diamond shows a sharp peak with a Raman shift of 1330 cm −1 and graphite with a Raman shift of 1580 cm −1 , and the ratio of the carbon component having a diamond structure and the carbon component having a graphite structure is simply determined from the intensity ratio. Can do. Diamond has high strength, high density, and high insulation, and graphite has excellent electrical conductivity. Therefore, the carbon film satisfying the above peak intensity ratio is optimized for each of the above characteristics, and as a result, it is possible to prevent electrode destruction due to expansion / contraction of the electrode material during charge / discharge and to have a negative electrode active material having a conductive network It becomes.

また、炭素被膜の含有率が、ケイ素系活物質粒子に対し０．１質量％以上２５質量％以下であることが好ましい。この炭素被膜の含有率は、４質量％以上２０質量％以下であることがより好ましい。   Moreover, it is preferable that the content rate of a carbon film is 0.1 to 25 mass% with respect to silicon type active material particle. The carbon film content is more preferably 4% by mass or more and 20% by mass or less.

この含有率が０．１質量％以上であれば、ケイ素系活物質粒子の電気伝導性を確実に向上させることが可能である。また、含有率が２５質量％以下であれば、電池特性が向上し、電池容量が大きくなる。炭素系化合物の被覆手法は特に限定されないが、糖炭化法、炭化水素ガスの熱分解法が好ましい。この場合、炭素被膜は炭素を含む化合物を熱分解することで得られたものである。これらのような方法により黒鉛等の炭素材を含む炭素被膜を形成することができる。また、これらの方法であれば、ケイ素系活物質粒子の表面における、炭素被膜の被覆率を向上させることができる。   If this content is 0.1% by mass or more, it is possible to reliably improve the electrical conductivity of the silicon-based active material particles. On the other hand, when the content is 25% by mass or less, the battery characteristics are improved and the battery capacity is increased. The coating method of the carbon-based compound is not particularly limited, but a sugar carbonization method and a hydrocarbon gas pyrolysis method are preferable. In this case, the carbon coating is obtained by thermally decomposing a compound containing carbon. A carbon film containing a carbon material such as graphite can be formed by such a method. Moreover, with these methods, the coverage of the carbon coating on the surface of the silicon-based active material particles can be improved.

また、本発明においては、ケイ素系活物質粒子の表面における炭素被膜の平均厚さが、５ｎｍ以上５０００ｎｍ以下であることが好ましい。特に、炭素被膜の平均厚さが、５ｎｍ以上５００ｎｍ以下であることがより好ましい。平均厚さが５ｎｍ以上であれば、十分な導電性が得られ、導電性の向上に伴い、電池特性は向上する。また、平均厚さが５０００ｎｍ以下であれば、ケイ素系活物質粒子の粒径に対し、炭素被膜の厚さが大きくなり過ぎず、負極活物質中のケイ素化合物の割合を高く維持でき、非水電解質二次電池とした場合のエネルギー密度が向上する。さらに、平均厚さが５００ｎｍ以下であれば負極活物質中のケイ素化合物の割合をより一層高く維持できる。なお、ケイ素系活物質粒子における、炭素被膜の平均厚さは、ＦＩＢ−ＴＥＭ（Ｆｏｃｕｓｅｄ Ｉｏｎ Ｂｅａｍ − Ｔｒａｎｓｍｉｓｓｉｏｎ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｅ）による断面観察により求めることができる。   Moreover, in this invention, it is preferable that the average thickness of the carbon film in the surface of a silicon type active material particle is 5 nm or more and 5000 nm or less. In particular, the average thickness of the carbon coating is more preferably 5 nm or more and 500 nm or less. If average thickness is 5 nm or more, sufficient electroconductivity will be acquired and a battery characteristic will improve with an electroconductive improvement. In addition, if the average thickness is 5000 nm or less, the thickness of the carbon coating does not become too large with respect to the particle size of the silicon-based active material particles, and the ratio of the silicon compound in the negative electrode active material can be maintained high. The energy density in the case of an electrolyte secondary battery is improved. Furthermore, if the average thickness is 500 nm or less, the ratio of the silicon compound in the negative electrode active material can be kept higher. Note that the average thickness of the carbon coating in the silicon-based active material particles can be determined by cross-sectional observation using FIB-TEM (Focused Ion Beam-Transmission Electron Microscope).

また、本発明において、ケイ素系活物質粒子の表面における炭素被膜の平均被覆率が、３０％以上であることが好ましい。平均被覆率が３０％以上であれば、炭素成分が導電性向上に特に有効に働き、電池特性が向上する。なお、平均被覆率は、ＳＥＭ−ＥＤＸ（Ｓｃａｎｎｉｎｇ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｅ − Ｅｎｅｒｇｙ Ｄｉｓｐｅｒｓｉｖｅ Ｘ−ｒａｙ Ｓｐｅｃｔｒｏｓｃｏｐｅ）による局所組成解析により、表面の（炭素の検出強度）／（ケイ素の検出強度）として定義した。   In the present invention, the average coverage of the carbon coating on the surface of the silicon-based active material particles is preferably 30% or more. When the average coverage is 30% or more, the carbon component works particularly effectively for improving the conductivity, and the battery characteristics are improved. The average coverage was defined as surface (carbon detection intensity) / (silicon detection intensity) by local composition analysis using SEM-EDX (Scanning Electron Microscope-Energy Dispersive X-ray Spectroscope).

また、本発明において、ケイ素系活物質粒子の表面における炭素被膜は、ＴＯＦ−ＳＩＭＳによって、ＣｙＨｚ系化合物のフラグメントが検出され、該ＣｙＨｚ系化合物のフラグメントとして、６≧ｙ≧２、２ｙ＋２≧ｚ≧２ｙ−２の範囲を満たすものが少なくとも一部に検出されることが好ましい。ＣｙＨｚ系フラグメントのような化合物フラグメントが検出される表面状態であれば、ＣＭＣやポリイミドなどの負極バインダーとの相性がよくなり、電池特性が向上する。 Further, in the present invention, the carbon coating on the surface of the silicon-based active material particles by TOF-SIMS, fragment C y H z type compounds are detected, as a fragment of the C y H z type compounds, 6 ≧ y ≧ Preferably, those satisfying the range of 2, 2y + 2 ≧ z ≧ 2y−2 are at least partially detected. If the surface state is such that a compound fragment such as a C y H z- based fragment is detected, compatibility with a negative electrode binder such as CMC or polyimide is improved, and battery characteristics are improved.

この場合、特に、炭素被膜で検出されるＣｙＨｚ系化合物のフラグメントは、ＴＯＦ−ＳＩＭＳにおけるＣ４Ｈ９の検出強度ＤとＣ３Ｈ５の検出強度Ｅが２．５≧Ｄ／Ｅ≧０．３の関係を満たすものであることが好ましい。上記検出強度の比Ｄ／Ｅが２．５以下であれば、表面の電気抵抗が小さいため、導電性が向上し、電池特性が向上する。また、上記検出強度の比Ｄ／Ｅが０．３以上であれば、表面の炭素被膜を十分に形成できている状態であるため、表面全体で炭素被膜により導電性が向上し、電池特性が向上する。また、検出されるＣｙＨｚ系化合物のフラグメントの種類および量は、ＣＶＤ条件（ガス、温度）及びその後処理条件を変えることで調整可能である。ここでいう後処理としては、ＣＶＤ処理後に、例えば、９５０〜１２００℃で、真空あるいはアルゴン雰囲気下で行う焼成処理などが挙げられる。 In this case, in particular, the fragment of the C y H z compound detected by the carbon coating has a detection intensity D of C 4 H 9 and a detection intensity E of C 3 H 5 of 2.5 ≧ D / E in TOF-SIMS. It is preferable that the relationship of ≧ 0.3 is satisfied. If the ratio D / E of the detected intensity is 2.5 or less, the electrical resistance of the surface is small, so that the conductivity is improved and the battery characteristics are improved. Further, if the ratio D / E of the detected intensity is 0.3 or more, the carbon coating on the surface is sufficiently formed, so that the conductivity is improved by the carbon coating on the entire surface, and the battery characteristics are improved. improves. In addition, the type and amount of the C y H z -based compound fragment to be detected can be adjusted by changing the CVD conditions (gas, temperature) and subsequent processing conditions. As post-processing here, the baking processing etc. which are performed in a vacuum or argon atmosphere after CVD processing at 950-1200 degreeC, etc. are mentioned, for example.

ＴＯＦ−ＳＩＭＳは、例えば下記条件で測定を行うことができる。
アルバック・ファイ社製 ＰＨＩ ＴＲＩＦＴ ２
・一次イオン源：Ｇａ
・試料温度：２５℃
・加速電圧：５ｋＶ
・スポットサイズ：１００μｍ×１００μｍ
・スパッタ：Ｇａ、１００μｍ×１００μｍ、１０ｓ
・陰イオン質量スペクトル
・サンプル：圧粉ペレット TOF-SIMS can be measured, for example, under the following conditions.
PHI TRIFT 2 made by ULVAC-PHI
・ Primary ion source: Ga
-Sample temperature: 25 ° C
・ Acceleration voltage: 5 kV
・ Spot size: 100μm × 100μm
Sputtering: Ga, 100 μm × 100 μm, 10 s
・ Anion mass spectrum ・ Sample ： Powder pellet

また、ケイ素系活物質粒子に含まれるケイ素化合物において、２９Ｓｉ−ＭＡＳ−ＮＭＲ スペクトルから得られるケミカルシフト値として、−２０〜−７４ｐｐｍで与えられるアモルファスシリコン領域のピーク面積Ａと−７５〜−９４ｐｐｍで与えられる結晶性シリコン領域及びＬｉシリケート領域のピーク面積Ｂと−９５〜−１５０ｐｐｍに与えられるシリカ領域のピーク面積Ｃが式（１）を満たすことが好ましい。なお、ケミカルシフトはテトラメチルシランを基準としたものである。
式（１）：５．０≧Ａ／Ｂ≧０．０１、６．０≧（Ａ＋Ｂ）／Ｃ≧０．０２ Further, in the silicon compound contained in the silicon-based active material particles, the peak area A of the amorphous silicon region given by −20 to −74 ppm and −75 to −94 ppm as the chemical shift value obtained from the 29 Si-MAS-NMR spectrum. It is preferable that the peak area B of the crystalline silicon region and the Li silicate region given by the formula (1) and the peak area C of the silica region given to -95 to -150 ppm satisfy the formula (1). The chemical shift is based on tetramethylsilane.
Formula (1): 5.0 ≧ A / B ≧ 0.01, 6.0 ≧ (A + B) /C≧0.02

Ｌｉの挿入に伴う膨張が抑えられるアモルファスシリコンの割合が高いほど、電池とした時に、負極の膨張が抑えられ、サイクル特性が向上する。また、上記式（１）の範囲を満たすものであれば、アモルファスシリコンや結晶性シリコンといったシリコン成分及びＬｉ２ＳｉＯ３等のＬｉシリケート成分に対してシリカ成分の割合が小さいので、ケイ素化合物内での電子伝導性の低下を抑制できるため、電池特性を向上させることができる。 The higher the proportion of amorphous silicon that can suppress the expansion associated with the insertion of Li, the lower the expansion of the negative electrode when the battery is made, and the cycle characteristics are improved. In addition, since the ratio of the silica component to the silicon component such as amorphous silicon and crystalline silicon and the Li silicate component such as Li 2 SiO 3 is small as long as the range of the above formula (1) is satisfied, Therefore, the battery characteristics can be improved.

また、本発明の負極活物質は、負極活物質粒子において、２９Ｓｉ−ＭＡＳ−ＮＭＲ スペクトルから得られる、ケミカルシフト値として−７５〜−９４ｐｐｍで与えられる結晶性シリコン領域及びＬｉシリケート領域の最大ピーク強度値Ｈと、ケミカルシフト値として−９５〜−１５０ｐｐｍで与えられるシリカ領域のピーク強度値Ｉが、Ｈ＞Ｉという関係を満たすものであることが好ましい。ケイ素化合物粒子において、ＳｉＯ２成分を基準とした場合にケイ素成分やＬｉ２ＳｉＯ３等のＬｉシリケート成分の量が比較的多いものであれば、Ｌｉの挿入による電池特性の向上効果を十分に得られる。 Further, the negative electrode active material of the present invention is the maximum peak of the crystalline silicon region and the Li silicate region, which are obtained from the 29 Si-MAS-NMR spectrum and given as a chemical shift value of −75 to −94 ppm in the negative electrode active material particles. It is preferable that the intensity value H and the peak intensity value I of the silica region given as −95 to −150 ppm as the chemical shift value satisfy the relationship of H> I. If the silicon compound particles have a relatively large amount of silicon silicate component or Li silicate component such as Li 2 SiO 3 when the SiO 2 component is used as a reference, the effect of improving battery characteristics by inserting Li can be sufficiently obtained. It is done.

２９Ｓｉ−ＭＡＳ−ＮＭＲ スペクトルは、例えば下記条件で測定を行うことができる。
２９Ｓｉ ＭＡＳ ＮＭＲ（マジック角回転核磁気共鳴）
・装置： Ｂｒｕｋｅｒ社製７００ＮＭＲ分光器
・プローブ： ４ｍｍＨＲ−ＭＡＳローター ５０μＬ
・試料回転速度： １０ｋＨｚ
・測定環境温度： ２５℃ The 29 Si-MAS-NMR spectrum can be measured, for example, under the following conditions.
29 Si MAS NMR (magic angle rotating nuclear magnetic resonance)
Apparatus: 700 NMR spectrometer manufactured by Bruker, Inc. Probe: 4 mm HR-MAS rotor 50 μL
・ Sample rotation speed: 10 kHz
・ Measurement environment temperature: 25 ℃

ケイ素系活物質粒子のメディアン径は特に限定されないが、中でも０．５μｍ以上２０μｍ以下であることが好ましい。この範囲であれば、充放電時においてリチウムイオンの吸蔵放出がされやすくなるとともに、粒子が割れにくくなるからである。このメディアン径が０．５μｍ以上であれば表面積が増加することがないため、電池不可逆容量を低減することができる。一方、メディアン径が２０μｍ以下であれば、粒子が割れにくく、新生面が出にくいため好ましい。   The median diameter of the silicon-based active material particles is not particularly limited, but is preferably 0.5 μm or more and 20 μm or less. This is because, within this range, lithium ions are easily occluded and released during charging and discharging, and the particles are difficult to break. If this median diameter is 0.5 μm or more, the surface area will not increase, and the battery irreversible capacity can be reduced. On the other hand, if the median diameter is 20 μm or less, it is preferable because the particles are difficult to break and a new surface is hardly produced.

また、本発明において、ケイ素系活物質粒子に含まれるケイ素化合物のＸ線回折により得られる（１１１）結晶面に起因する回折ピークの半値幅（２θ）が１．２°以上であることが好ましく、また、その結晶面に起因する結晶子サイズが７．５ｎｍ以下であることが好ましい。このような半値幅及び結晶子サイズを有するケイ素化合物は結晶性の低いものである。このように結晶性が低くＳｉ結晶の存在量が少ないケイ素化合物を用いることにより、電池特性を向上させることができる。また、このような結晶性の低いケイ素化合物が存在することで、安定的なＬｉ化合物の生成を行うことができる。   In the present invention, the half width (2θ) of the diffraction peak derived from the (111) crystal plane obtained by X-ray diffraction of the silicon compound contained in the silicon-based active material particles is preferably 1.2 ° or more. Moreover, it is preferable that the crystallite size resulting from the crystal plane is 7.5 nm or less. A silicon compound having such a half width and crystallite size has low crystallinity. By using a silicon compound having low crystallinity and a small amount of Si crystals, battery characteristics can be improved. In addition, the presence of such a low-crystallinity silicon compound makes it possible to generate a stable Li compound.

また、本発明において、ケイ素系活物質粒子の少なくとも一部にＬｉを含有することが好ましい。ケイ素系活物質粒子にＬｉを含有させるには、Ｌｉをケイ素化合物にドープすればよい。Ｌｉをケイ素化合物にドープする方法としては、例えば、ケイ素系活物質粒子と金属リチウムを混合して加熱する熱ドープ法や、電気化学的方法があげられる。ケイ素化合物に、Ｌｉ化合物が含まれていることにより、初回効率が向上する。また、非水電解質二次電池とした場合の負極の初回効率が上昇するため、サイクル試験時の正極と負極のバランスずれが抑制され、維持率が向上する。   In the present invention, it is preferable that at least a part of the silicon-based active material particles contains Li. In order to contain Li in silicon-based active material particles, Li may be doped into a silicon compound. Examples of a method for doping Li into a silicon compound include a thermal doping method in which silicon-based active material particles and metallic lithium are mixed and heated, and an electrochemical method. By including the Li compound in the silicon compound, the initial efficiency is improved. In addition, since the initial efficiency of the negative electrode in the case of a nonaqueous electrolyte secondary battery is increased, a deviation in the balance between the positive electrode and the negative electrode during the cycle test is suppressed, and the maintenance ratio is improved.

また、ケイ素系活物質粒子がＬｉを含有する場合、ケイ素系活物質粒子の少なくとも一部に、Ｌｉ２ＳｉＯ３及びＬｉ４ＳｉＯ４のうち少なくとも１種以上を含有することが好ましい。ケイ素系活物質粒子が、Ｌｉ化合物として比較的安定している上記のＬｉシリケートを含んでいれば、電極作製時のスラリーに対する安定性がより向上する。 In addition, when the silicon-based active material particles contain Li, it is preferable that at least a part of the silicon-based active material particles contains at least one of Li 2 SiO 3 and Li 4 SiO 4 . If the silicon-based active material particles contain the above-described Li silicate that is relatively stable as a Li compound, the stability with respect to the slurry during electrode production is further improved.

また、Ｌｉをケイ素化合物にドープする方法としては、酸化還元法を用いることもできる。酸化還元法による改質では、例えば、まず、エーテル溶媒にリチウムを溶解した溶液Ａにケイ素化合物粒子を浸漬することで、リチウムを挿入できる。この溶液Ａに更に多環芳香族化合物又は直鎖ポリフェニレン化合物を含ませても良い。リチウムの挿入後、多環芳香族化合物やその誘導体を含む溶液Ｂにケイ素化合物粒子を浸漬することで、ケイ素化合物粒子から活性なリチウムを脱離できる。この溶液Ｂの溶媒は例えば、エーテル系溶媒、ケトン系溶媒、エステル系溶媒、アルコール系溶媒、アミン系溶媒、又はこれらの混合溶媒を使用できる。さらに、溶液Ｂに浸漬した後、アルコール系溶媒、カルボン酸系溶媒、水、又はこれらの混合溶媒を含む溶液Ｃにケイ素化合物粒子を浸漬することで、ケイ素化合物粒子から活性なリチウムをより多く脱離できる。また、溶液Ｃの代わりに、溶質として分子中にキノイド構造を持つ化合物を含み、溶媒としてエーテル系溶媒、ケトン系溶媒、エステル系溶媒、又はこれらの混合溶媒を含む溶液Ｃ’を用いても良い。また、溶液Ｂ、Ｃ、Ｃ’へのケイ素化合物粒子の浸漬は繰り返し行っても良い。このようにして、リチウムの挿入後、活性なリチウムを脱離すれば、より耐水性の高い負極活物質となる。その後、アルコール、炭酸リチウムを溶解したアルカリ水、弱酸、又は純水などで洗浄しても良い。   Further, as a method for doping Li into a silicon compound, an oxidation-reduction method can also be used. In the modification by the redox method, for example, lithium can be inserted by first immersing silicon compound particles in a solution A in which lithium is dissolved in an ether solvent. The solution A may further contain a polycyclic aromatic compound or a linear polyphenylene compound. After insertion of lithium, active lithium can be desorbed from the silicon compound particles by immersing the silicon compound particles in a solution B containing a polycyclic aromatic compound or a derivative thereof. As the solvent of the solution B, for example, an ether solvent, a ketone solvent, an ester solvent, an alcohol solvent, an amine solvent, or a mixed solvent thereof can be used. Furthermore, after immersing in the solution B, the active lithium is removed from the silicon compound particles by immersing the silicon compound particles in a solution C containing an alcohol solvent, a carboxylic acid solvent, water, or a mixed solvent thereof. Can be separated. Instead of the solution C, a solution C ′ containing a compound having a quinoid structure in the molecule as a solute and containing an ether solvent, a ketone solvent, an ester solvent, or a mixed solvent thereof as a solvent may be used. . Further, the immersion of the silicon compound particles in the solutions B, C, and C ′ may be repeated. Thus, if active lithium is desorbed after insertion of lithium, a negative electrode active material with higher water resistance is obtained. Then, you may wash | clean with the alkaline water, weak acid, or pure water which melt | dissolved alcohol and lithium carbonate.

また、本発明の負極活物質（ケイ素系活物質）は、該ケイ素系活物質と炭素系活物質との混合物を含む負極電極と対極リチウムとから成る試験セルを作製し、該試験セルにおいて、ケイ素系活物質にリチウムを挿入するよう電流を流す充電と、ケイ素系活物質からリチウムを脱離するよう電流を流す放電とから成る充放電を３０回実施し、各充放電における放電容量Ｑを対極リチウムを基準とする負極電極の電位Ｖで微分した微分値ｄＱ／ｄＶと電位Ｖとの関係を示すグラフを描いた場合に、Ｘ回目以降（１≦Ｘ≦３０）の放電時における、負極電極の電位Ｖが０．４０Ｖ〜０．５５Ｖの範囲にピークを有するものであることが好ましい。Ｖ−ｄＱ／ｄＶ曲線における上記のピークはケイ素材のピークと類似しており、より高電位側における放電カーブが鋭く立ち上がるため、電池設計を行う際、容量発現しやすくなる。また、３０回以内の充放電で上記ピークが発現する負極活物質であれば、安定したバルクが形成されるものであると判断できる。   Moreover, the negative electrode active material (silicon-based active material) of the present invention is a test cell comprising a negative electrode containing a mixture of the silicon-based active material and a carbon-based active material and counter electrode lithium, and in the test cell, Charging / discharging consisting of charging in which current is inserted to insert lithium into the silicon-based active material and discharging in which current is discharged to detach lithium from the silicon-based active material is performed 30 times, and the discharge capacity Q in each charging / discharging is determined. When a graph showing the relationship between the differential value dQ / dV differentiated by the potential V of the negative electrode with respect to the counter electrode lithium and the potential V is drawn, the negative electrode during the Xth and subsequent discharges (1 ≦ X ≦ 30) The electrode potential V preferably has a peak in the range of 0.40V to 0.55V. The above peak in the V-dQ / dV curve is similar to the peak of the siliceous material, and the discharge curve on the higher potential side rises sharply, so that the capacity is easily developed when designing the battery. Moreover, if it is a negative electrode active material which the said peak expresses by charge / discharge within 30 times, it can be judged that the stable bulk is formed.

負極導電助剤としては、例えば、カーボンブラック、アセチレンブラック、鱗片状黒鉛等の黒鉛、ケチェンブラック、カーボンナノチューブ、カーボンナノファイバーなどの炭素材料（炭素系材料）のいずれか１種以上があげられる。これらの導電助剤は、ケイ素化合物よりもメディアン径の小さい粒子状のものであることが好ましい。   Examples of the negative electrode conductive aid include one or more of carbon materials such as carbon black, acetylene black, and graphite such as flaky graphite, and carbon materials (carbon-based materials) such as ketjen black, carbon nanotubes, and carbon nanofibers. . These conductive assistants are preferably in the form of particles having a median diameter smaller than that of the silicon compound.

本発明において、図１の負極活物質層１２は、本発明の負極活物質に加え、さらに、炭素系活物質粒子を含んでもよい。これにより、本発明の負極活物質が含まれる負極活物質層１２の電気抵抗を低下させるとともに、充電に伴う膨張応力を緩和することが可能となる。この炭素系活物質としては、例えば、熱分解炭素類、コークス類、ガラス状炭素繊維、有機高分子化合物焼成体、カーボンブラック類などが挙げられる。中でも、炭素系活物質粒子は、黒鉛材料であることが好ましい。黒鉛材料は、他の炭素系活物質粒子よりも良好な初回効率、容量維持率を発揮することができる。   In the present invention, the negative electrode active material layer 12 of FIG. 1 may further contain carbon-based active material particles in addition to the negative electrode active material of the present invention. As a result, it is possible to reduce the electrical resistance of the negative electrode active material layer 12 containing the negative electrode active material of the present invention and to relieve the expansion stress associated with charging. Examples of the carbon-based active material include pyrolytic carbons, cokes, glassy carbon fibers, organic polymer compound fired bodies, and carbon blacks. Among these, the carbon-based active material particles are preferably a graphite material. The graphite material can exhibit better initial efficiency and capacity retention than other carbon-based active material particles.

また、本発明において、ケイ素系活物質粒子と炭素系活物質粒子の合計の質量に対する、ケイ素系活物質粒子の質量の割合が５質量％以上であることが好ましい。また、ケイ素系活物質粒子質量の割合は９０質量％未満であることがより好ましい。このような割合でケイ素系活物質粒子を含む負極活物質であれば、非水電解質二次電池の負極に使用した場合に、良好な初回効率及び容量維持率が得られる。もちろん、ケイ素系活物質粒子の質量の割合が９０質量％以上１００質量％以下であっても、本発明の負極活物質を使用すれば、高電池容量、良好なサイクル特性、及び良好な初回充放電特性が得られる。   In the present invention, the ratio of the mass of the silicon-based active material particles to the total mass of the silicon-based active material particles and the carbon-based active material particles is preferably 5% by mass or more. Further, the ratio of the mass of the silicon-based active material particles is more preferably less than 90% by mass. If it is a negative electrode active material containing silicon-based active material particles at such a ratio, good initial efficiency and capacity retention can be obtained when used for the negative electrode of a non-aqueous electrolyte secondary battery. Of course, even if the mass ratio of the silicon-based active material particles is 90% by mass or more and 100% by mass or less, if the negative electrode active material of the present invention is used, high battery capacity, good cycle characteristics, and good initial charge are obtained. Discharge characteristics can be obtained.

また、ケイ素系活物質粒子の平均粒径Ｆが、炭素系活物質粒子の平均粒径Ｇに対し、２５≧Ｇ／Ｆ≧０．５の関係を満たすことが好ましい。すなわち、炭素系活物質粒子の平均粒径が、ケイ素系活物質粒子の平均粒径と略同等以上の大きさであることが望ましい。これは、電池の充放電の際のＬｉ挿入・脱離に伴い膨張収縮するケイ素系活物質粒子が炭素系活物質粒子に対して同等以下の大きさである場合、合材層の破壊を防止することができるからである。このように、炭素系活物質粒子がケイ素系活物質粒子に対して大きくなると、充電時の負極体積密度、初期効率が向上し、電池エネルギー密度が向上する。   The average particle size F of the silicon-based active material particles preferably satisfies the relationship of 25 ≧ G / F ≧ 0.5 with respect to the average particle size G of the carbon-based active material particles. That is, it is desirable that the average particle diameter of the carbon-based active material particles is approximately equal to or greater than the average particle diameter of the silicon-based active material particles. This prevents the destruction of the composite layer when the silicon-based active material particles that expand and contract with Li insertion / extraction during battery charging / discharging are the same or smaller than the carbon-based active material particles. Because it can be done. Thus, when the carbon-based active material particles are larger than the silicon-based active material particles, the negative electrode volume density and initial efficiency during charging are improved, and the battery energy density is improved.

図１の負極活物質層１２は、例えば塗布法で形成される。塗布法とはケイ素系活物質粒子と上記した結着剤など、また必要に応じて導電助剤、炭素系活物質粒子を混合したのち、有機溶剤や水などに分散させ塗布する方法である。   The negative electrode active material layer 12 in FIG. 1 is formed by, for example, a coating method. The coating method is a method in which silicon-based active material particles and the above-mentioned binder, etc., and a conductive additive and carbon-based active material particles are mixed as necessary, and then dispersed in an organic solvent or water for coating.

［負極の製造方法］
本発明の負極を製造する方法について説明する。 [Production method of negative electrode]
A method for producing the negative electrode of the present invention will be described.

最初に、負極に含まれる負極材の製造方法を説明する。まず、ＳｉＯｘ（０．５≦ｘ≦１．６）で表されるケイ素化合物を作製する。次に、ケイ素化合物の表面を炭素被膜で被覆する。ここで、ケイ素化合物にＬｉを挿入することにより、該ケイ素化合物の表面若しくは内部又はその両方にＬｉ化合物を生成させて該ケイ素化合物を改質してもよい。 Initially, the manufacturing method of the negative electrode material contained in a negative electrode is demonstrated. First, a silicon compound represented by SiO x (0.5 ≦ x ≦ 1.6) is produced. Next, the surface of the silicon compound is coated with a carbon film. Here, by inserting Li into the silicon compound, the silicon compound may be modified by generating the Li compound on the surface, inside, or both of the silicon compound.

その後、炭素被膜が被覆されたケイ素化合物の粒子の一部を取り出し、該取り出されたケイ素化合物の粒子から、炭素被膜を単離し、比表面積及び圧縮抵抗率を測定する。そして、炭素被膜を単離して測定した多点ＢＥＴ法による比表面積が５ｍ２／ｇ以上１０００ｍ２／ｇ以下であり、かつ、炭素被膜を単離して測定した圧縮抵抗率が、１．０ｇ／ｃｍ３の密度に圧縮した時に１．０×１０−３Ω・ｃｍ以上１．０Ω・ｃｍ以下、という条件を満たしたものを取り出した元の炭素被膜を被覆されたケイ素化合物の粒子を負極活物質粒子として選別する。 Thereafter, a part of the silicon compound particles coated with the carbon coating is taken out, the carbon coating is isolated from the taken out silicon compound particles, and the specific surface area and compression resistivity are measured. And the specific surface area by the multipoint BET method measured by isolating the carbon film is 5 m 2 / g or more and 1000 m 2 / g or less, and the compression resistivity measured by isolating the carbon film is 1.0 g / Particles of a silicon compound coated with an original carbon film taken out satisfying the condition of 1.0 × 10 −3 Ω · cm to 1.0 Ω · cm when compressed to a density of cm 3 are used as negative electrode actives. Sort as material particles.

より具体的には、負極材は、例えば、以下の手順により製造することができる。   More specifically, the negative electrode material can be manufactured, for example, by the following procedure.

まず、酸化珪素ガスを発生する原料（気化出発材）を不活性ガスの存在下もしくは減圧下９００℃〜１６００℃の温度範囲で加熱し、酸化ケイ素ガスを発生させる。この場合、原料は金属珪素粉末と二酸化珪素粉末との混合であり、金属珪素粉末の表面酸素及び反応炉中の微量酸素の存在を考慮すると、混合モル比が、０．８＜金属珪素粉末／二酸化珪素粉末＜１．３の範囲であることが望ましい。粒子中のＳｉ結晶子は仕込み範囲や気化温度の変更、また生成後の熱処理で制御される。発生したガスは吸着板に堆積される。反応炉内温度を１００℃以下に下げた状態で堆積物を取出し、ボールミル、ジェットミルなどを用いて粉砕、粉末化を行う。   First, a raw material (vaporization starting material) that generates silicon oxide gas is heated in the temperature range of 900 ° C. to 1600 ° C. in the presence of an inert gas or under reduced pressure to generate silicon oxide gas. In this case, the raw material is a mixture of metal silicon powder and silicon dioxide powder, and considering the surface oxygen of the metal silicon powder and the presence of trace amounts of oxygen in the reactor, the mixing molar ratio is 0.8 <metal silicon powder / It is desirable that the silicon dioxide powder is in the range of <1.3. The Si crystallites in the particles are controlled by changing the preparation range and vaporization temperature, and by heat treatment after generation. The generated gas is deposited on the adsorption plate. The deposit is taken out with the temperature in the reactor lowered to 100 ° C. or lower, and pulverized and powdered using a ball mill, a jet mill or the like.

次に、得られた粉末材料の表面に炭素被膜を被覆する。得られた粉末材料の表面に炭素被膜を生成する手法としては、熱ＣＶＤが望ましい。熱ＣＶＤでは、炉内に粉末材料をセットし、炭化水素ガスを充満させ炉内温度を昇温させる。分解温度は特に限定しないが特に１２００℃以下が望ましい。より望ましいのは９５０℃以下であり、ケイ素化合物の粒子の意図しない不均化を抑制することが可能である。   Next, a carbon film is coated on the surface of the obtained powder material. Thermal CVD is desirable as a method for generating a carbon film on the surface of the obtained powder material. In thermal CVD, a powder material is set in a furnace, and a hydrocarbon gas is filled to raise the temperature in the furnace. The decomposition temperature is not particularly limited, but is particularly preferably 1200 ° C. or lower. More desirably, the temperature is 950 ° C. or lower, and unintended disproportionation of the silicon compound particles can be suppressed.

熱ＣＶＤによって炭素被膜を形成する場合、炭素被膜をケイ素化合物の粒子から単離した際の比表面積及び圧縮抵抗率は、ＣＶＤ温度、時間及びＣＶＤ時の粉末材料（ケイ素化合物粉体）の攪拌度を調節することで制御できる。また、炭素被膜の量、厚み、被覆率、炭素被膜をケイ素化合物の粒子から単離した際の吸脱着等温線の分類も、ＣＶＤ温度、時間及びＣＶＤ時の粉末材料（ケイ素化合物粉体）の攪拌度を調節することで制御できる。また、炉内の温度を調節することによって、ラマンスペクトルにおけるピーク強度比Ｉ１３３０／Ｉ１５８０を調整することができる。また、炭素被膜の密度及び炭素被膜をケイ素化合物の粒子から単離した際の圧縮密度はＣＶＤ時のガス流量を調節することによって制御できる。 When a carbon film is formed by thermal CVD, the specific surface area and compression resistivity when the carbon film is isolated from the silicon compound particles are the CVD temperature, time, and degree of stirring of the powder material (silicon compound powder) during CVD. It can be controlled by adjusting. In addition, the amount of carbon coating, thickness, coverage, and adsorption / desorption isotherm classification when the carbon coating is isolated from silicon compound particles are also included in the CVD temperature, time, and CVD powder material (silicon compound powder). It can be controlled by adjusting the degree of stirring. In addition, the peak intensity ratio I 1330 / I 1580 in the Raman spectrum can be adjusted by adjusting the temperature in the furnace. The density of the carbon coating and the compression density when the carbon coating is isolated from the silicon compound particles can be controlled by adjusting the gas flow rate during CVD.

続いて、炭素被膜を被覆したケイ素化合物の粒子の一部を取り出し、例えば、上記した炭素被膜の単離方法、比表面積及び圧縮抵抗率の測定法を使用して、取り出されたケイ素化合物の粒子から炭素被膜を単離し、比表面積及び圧縮抵抗率を測定する。そして、炭素被膜を単離して測定した多点ＢＥＴ法による比表面積が５ｍ２／ｇ以上１０００ｍ２／ｇ以下であり、かつ、炭素被膜を単離して測定した圧縮抵抗率が、１．０ｇ／ｃｍ３の密度に圧縮した時に１．０×１０−３Ω・ｃｍ以上１．０Ω・ｃｍ以下、という条件を満たす場合に、取り出した元の炭素被膜を被覆されたケイ素化合物の粒子を負極活物質粒子として選別する。 Subsequently, a part of the silicon compound particles coated with the carbon film is taken out, for example, using the above-described carbon film isolation method, specific surface area and compression resistivity measurement method, the silicon compound particles taken out. The carbon film is isolated from the glass and the specific surface area and compression resistivity are measured. And the specific surface area by the multipoint BET method measured by isolating the carbon film is 5 m 2 / g or more and 1000 m 2 / g or less, and the compression resistivity measured by isolating the carbon film is 1.0 g / When compressed to a density of cm 3 , when the condition of 1.0 × 10 −3 Ω · cm to 1.0 Ω · cm is satisfied, the extracted silicon compound particles coated with the original carbon coating are used as the negative electrode active material. Sort as material particles.

尚、上記ケイ素化合物の粒子の選別は、必ずしも負極材の製造の都度行う必要はなく、一度、炭素被膜を単離して測定した多点ＢＥＴ法による比表面積が５ｍ２／ｇ以上１０００ｍ２／ｇ以下であり、かつ、炭素被膜を単離して測定した圧縮抵抗率が、１．０ｇ／ｃｍ３の密度に圧縮した時に１．０×１０−３Ω・ｃｍ以上１．０Ω・ｃｍ以下、という条件を満たす炭素被膜が得られる製造条件を見出して選択すれば、その後は、その選択された条件と同じ条件で負極材を製造することができる。 The selection of the silicon compound particles is not necessarily performed every time the negative electrode material is produced, and the specific surface area according to the multipoint BET method once measured by isolating the carbon coating is 5 m 2 / g or more and 1000 m 2 / g. And the compression resistivity measured by isolating the carbon film is 1.0 × 10 −3 Ω · cm to 1.0 Ω · cm when compressed to a density of 1.0 g / cm 3. If manufacturing conditions for obtaining a carbon coating that satisfies the conditions are found and selected, then the negative electrode material can be manufactured under the same conditions as the selected conditions.

このようにして選別した炭素被膜を有するケイ素化合物の粒子を負極活物質粒子として、非水電解質二次電池用負極材を作製する。   A negative electrode material for a non-aqueous electrolyte secondary battery is prepared using the silicon compound particles having the carbon coating thus selected as negative electrode active material particles.

続いて、負極活物質粒子、負極結着剤、及び導電助剤など他の材料とを混合し負極合剤としたのち、有機溶剤又は水などを加えてスラリーとする。   Subsequently, the negative electrode active material particles, the negative electrode binder, and other materials such as a conductive additive are mixed to form a negative electrode mixture, and then an organic solvent or water is added to obtain a slurry.

次に、負極集電体の表面に負極合剤のスラリーを塗布し、乾燥させて図１に示す負極活物質層１２を形成する。この時、必要に応じて加熱プレスなどを行っても良い。このようにして負極を製造できる。   Next, a negative electrode mixture slurry is applied to the surface of the negative electrode current collector and dried to form the negative electrode active material layer 12 shown in FIG. At this time, a heating press or the like may be performed as necessary. Thus, a negative electrode can be manufactured.

また、ケイ素系活物質粒子よりメディアン径の小さい炭素系材料を導電助剤として添加する場合、例えば、アセチレンブラックを選択して添加することができる。   Further, when a carbon-based material having a median diameter smaller than that of the silicon-based active material particles is added as a conductive additive, for example, acetylene black can be selected and added.

炭化水素ガスは特に限定することはないが、ＣｎＨｍ組成のうち３≧ｎが望ましい。製造コストを低くすることができ、分解生成物の物性が良いからである。 Hydrocarbon gas is not particularly limited, 3 ≧ n of C n H m composition it is desirable. This is because the manufacturing cost can be lowered and the physical properties of the decomposition product are good.

＜２．リチウムイオン二次電池＞
次に、本発明の負極活物質を含むリチウムイオン二次電池について説明する。 <2. Lithium ion secondary battery>
Next, a lithium ion secondary battery containing the negative electrode active material of the present invention will be described.

［ラミネートフィルム型リチウムイオン二次電池の構成］
図３に示すラミネートフィルム型二次電池２０は、主にシート状の外装部材２５の内部に巻回電極体２１が収納されたものである。この巻回体は正極、負極間にセパレータを有し、巻回されたものである。また正極、負極間にセパレータを有し積層体を収納した場合も存在する。どちらの電極体においても、正極に正極リード２２が取り付けられ、負極に負極リード２３が取り付けられている。電極体の最外周部は保護テープにより保護されている。 [Configuration of laminated film type lithium ion secondary battery]
A laminated film type secondary battery 20 shown in FIG. 3 is one in which a wound electrode body 21 is accommodated mainly in a sheet-like exterior member 25. This wound body has a separator between a positive electrode and a negative electrode and is wound. There is also a case where a separator is provided between the positive electrode and the negative electrode and a laminate is accommodated. In both electrode bodies, the positive electrode lead 22 is attached to the positive electrode, and the negative electrode lead 23 is attached to the negative electrode. The outermost peripheral part of the electrode body is protected by a protective tape.

正負極リードは、例えば外装部材２５の内部から外部に向かって一方向で導出されている。正極リード２２は、例えば、アルミニウムなどの導電性材料により形成され、負極リード２３は、例えば、ニッケル、銅などの導電性材料により形成される。   The positive and negative electrode leads are led out in one direction from the inside of the exterior member 25 to the outside, for example. The positive electrode lead 22 is formed of a conductive material such as aluminum, and the negative electrode lead 23 is formed of a conductive material such as nickel or copper.

外装部材２５は、例えば融着層、金属層、表面保護層がこの順に積層されたラミネートフィルムであり、このラミネートフィルムは融着層が電極体２１と対向するように、２枚のフィルムの融着層における外周縁部同士が融着、又は接着剤などで張り合わされている。融着部は、例えばポリエチレンやポリプロピレンなどのフィルムであり、金属部はアルミ箔などである。保護層は例えば、ナイロンなどである。   The exterior member 25 is, for example, a laminate film in which a fusion layer, a metal layer, and a surface protective layer are laminated in this order. The laminate film is formed by fusing two films so that the fusion layer faces the electrode body 21. The outer peripheral edge portions in the adhesion layer are bonded together with an adhesive or the like. The fused part is, for example, a film such as polyethylene or polypropylene, and the metal part is aluminum foil or the like. The protective layer is, for example, nylon.

外装部材２５と正負極リードとの間には、外気侵入防止のため密着フィルム２４が挿入されている。この材料は、例えばポリエチレン、ポリプロピレン、ポリオレフィン樹脂である。   An adhesion film 24 is inserted between the exterior member 25 and the positive and negative electrode leads to prevent intrusion of outside air. This material is, for example, polyethylene, polypropylene, or polyolefin resin.

［正極］
正極は、例えば、図１の負極１０と同様に、正極集電体の両面又は片面に正極活物質層を有している。 [Positive electrode]
The positive electrode has, for example, a positive electrode active material layer on both sides or one side of the positive electrode current collector, similarly to the negative electrode 10 of FIG.

正極集電体は、例えば、アルミニウムなどの導電性材により形成されている。   The positive electrode current collector is formed of, for example, a conductive material such as aluminum.

正極活物質層は、リチウムイオンの吸蔵放出可能な正極材のいずれか１種又は２種以上を含んでおり、設計に応じて結着剤、導電助剤、分散剤などの他の材料を含んでいても良い。この場合、結着剤、導電助剤に関する詳細は、例えば既に記述した負極結着剤、負極導電助剤と同様である。   The positive electrode active material layer includes one or more positive electrode materials capable of occluding and releasing lithium ions, and includes other materials such as a binder, a conductive additive, and a dispersant depending on the design. You can leave. In this case, details regarding the binder and the conductive additive are the same as, for example, the negative electrode binder and the negative electrode conductive additive already described.

正極材料としては、リチウム含有化合物が望ましい。このリチウム含有化合物は、例えばリチウムと遷移金属元素からなる複合酸化物、又はリチウムと遷移金属元素を有するリン酸化合物があげられる。これらの正極材の中でもニッケル、鉄、マンガン、コバルトの少なくとも１種以上を有する化合物が好ましい。これらの化学式として、例えば、ＬｉｘＭ１Ｏ２あるいはＬｉｙＭ２ＰＯ４で表される。式中、Ｍ１、Ｍ２は少なくとも１種以上の遷移金属元素を示す。ｘ、ｙの値は電池充放電状態によって異なる値を示すが、一般的に０．０５≦ｘ≦１．１０、０．０５≦ｙ≦１．１０で示される。 As the positive electrode material, a lithium-containing compound is desirable. Examples of the lithium-containing compound include a composite oxide composed of lithium and a transition metal element, or a phosphate compound having lithium and a transition metal element. Among these positive electrode materials, compounds having at least one of nickel, iron, manganese and cobalt are preferable. These chemical formulas are represented by, for example, Li x M 1 O 2 or Li y M 2 PO 4 . In the formula, M 1 and M 2 represent at least one transition metal element. The values of x and y vary depending on the battery charge / discharge state, but are generally expressed as 0.05 ≦ x ≦ 1.10 and 0.05 ≦ y ≦ 1.10.

リチウムと遷移金属元素とを有する複合酸化物としては、例えば、リチウムコバルト複合酸化物（ＬｉｘＣｏＯ２）、リチウムニッケル複合酸化物（ＬｉｘＮｉＯ２）、リチウムと遷移金属元素とを有するリン酸化合物としては、例えば、リチウム鉄リン酸化合物（ＬｉＦｅＰＯ４）あるいはリチウム鉄マンガンリン酸化合物（ＬｉＦｅ１−ｕＭｎｕＰＯ４（ｕ＜１））などが挙げられる。これらの正極材を用いれば、高い電池容量が得られるとともに、優れたサイクル特性も得られるからである。 Examples of the composite oxide having lithium and a transition metal element include lithium cobalt composite oxide (Li x CoO 2 ), lithium nickel composite oxide (Li x NiO 2 ), and phosphoric acid having lithium and a transition metal element. Examples of the compound include a lithium iron phosphate compound (LiFePO 4 ) and a lithium iron manganese phosphate compound (LiFe 1-u Mn u PO 4 (u <1)). This is because, when these positive electrode materials are used, a high battery capacity can be obtained and excellent cycle characteristics can be obtained.

［負極］
負極は、上記した図１のリチウムイオン二次電池用負極１０と同様の構成を有し、例えば、本発明の負極活物質を含む負極活物質層１２を集電体１１の両面に有している。この負極は、正極活物質剤から得られる電気容量（電池としての充電容量）に対して、負極充電容量が大きくなることが好ましい。負極上でのリチウム金属の析出を抑制することができるためである。 [Negative electrode]
The negative electrode has the same configuration as the negative electrode 10 for lithium ion secondary battery in FIG. 1 described above. For example, the negative electrode active material layer 12 containing the negative electrode active material of the present invention is provided on both surfaces of the current collector 11. Yes. This negative electrode preferably has a negative electrode charge capacity larger than the electric capacity (charge capacity as a battery) obtained from the positive electrode active material agent. This is because the deposition of lithium metal on the negative electrode can be suppressed.

正極活物質層は、正極集電体の両面の一部に設けられており、負極活物質層も負極集電体の両面の一部に設けられている。この場合、例えば、負極集電体上に設けられた負極活物質層は対向する正極活物質層が存在しない領域が設けられている。安定した電池設計を行うためである。   The positive electrode active material layer is provided on part of both surfaces of the positive electrode current collector, and the negative electrode active material layer is also provided on part of both surfaces of the negative electrode current collector. In this case, for example, the negative electrode active material layer provided on the negative electrode current collector is provided with a region where there is no opposing positive electrode active material layer. This is for a stable battery design.

非対向領域、即ち、上記の負極活物質層と正極活物質層とが対向しない領域では、充放電の影響をほとんど受けることが無い。そのため負極活物質層の状態が形成直後のまま維持される。これによって負極活物質の組成など、充放電の有無に依存せずに再現性良く組成などを正確に調べることができる。   In the non-opposing region, that is, the region where the negative electrode active material layer and the positive electrode active material layer do not face each other, there is almost no influence of charge / discharge. Therefore, the state of the negative electrode active material layer is maintained as it is immediately after formation. This makes it possible to accurately examine the composition with good reproducibility without depending on the presence or absence of charge / discharge, such as the composition of the negative electrode active material.

［セパレータ］
セパレータは正極、負極を隔離し、両極接触に伴う電流短絡を防止しつつ、リチウムイオンを通過させるものである。このセパレータは、例えば合成樹脂、あるいはセラミックからなる多孔質膜により形成されており、２種以上の多孔質膜が積層された積層構造を有しても良い。合成樹脂として例えば、ポリテトラフルオロエチレン、ポリプロピレンあるいはポリエチレンなどが挙げられる。 [Separator]
The separator separates the positive electrode and the negative electrode, and allows lithium ions to pass through while preventing current short-circuiting due to bipolar contact. This separator is formed of, for example, a porous film made of synthetic resin or ceramic, and may have a laminated structure in which two or more kinds of porous films are laminated. Examples of the synthetic resin include polytetrafluoroethylene, polypropylene, and polyethylene.

［電解液］
活物質層の少なくとも一部、又はセパレータには液状の電解質（電解液）が含浸されている。この電解液は、溶媒中に電解質塩が溶解されており、添加剤など他の材料を含んでいても良い。 [Electrolyte]
At least a part of the active material layer or the separator is impregnated with a liquid electrolyte (electrolytic solution). This electrolytic solution has an electrolyte salt dissolved in a solvent, and may contain other materials such as additives.

溶媒は、例えば非水溶媒を用いることができる。非水溶媒としては、例えば、次の材料が挙げられる。炭酸エチレン、炭酸プロピレン、炭酸ブチレン、炭酸ジメチル、炭酸ジエチル、炭酸エチルメチル、炭酸メチルプロピル、１，２−ジメトキシエタン、あるいはテトラヒドロフランである。   For example, a non-aqueous solvent can be used as the solvent. Examples of the nonaqueous solvent include the following materials. Ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, 1,2-dimethoxyethane, or tetrahydrofuran.

中でも、炭酸エチレン、炭酸プロピレン、炭酸ジメチル、炭酸ジエチル、炭酸エチルメチルのうちの少なくとも１種以上が望ましい。より良い特性が得られるからである。またこの場合、炭酸エチレン、炭酸プロピレンなどの高粘度溶媒と、炭酸ジメチル、炭酸エチルメチル、炭酸ジエチルなどの低粘度溶媒を組み合わせるとより優位な特性を得ることができる。電解質塩の解離性やイオン移動度が向上するためである。   Among these, at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate is desirable. This is because better characteristics can be obtained. In this case, more advantageous characteristics can be obtained by combining a high viscosity solvent such as ethylene carbonate or propylene carbonate and a low viscosity solvent such as dimethyl carbonate, ethyl methyl carbonate or diethyl carbonate. This is because the dissociation property and ion mobility of the electrolyte salt are improved.

溶媒添加物として、不飽和炭素結合環状炭酸エステルを含んでいることが好ましい。充放電時に負極表面に安定な被膜が形成され、電解液の分解反応が抑制できるからである。不飽和炭素結合環状炭酸エステルとして、例えば炭酸ビニレン又は炭酸ビニルエチレンなどがあげられる。   The solvent additive preferably contains an unsaturated carbon bond cyclic carbonate. This is because a stable film is formed on the surface of the negative electrode during charging and discharging, and the decomposition reaction of the electrolytic solution can be suppressed. Examples of the unsaturated carbon bond cyclic ester carbonate include vinylene carbonate and vinyl ethylene carbonate.

また溶媒添加物として、スルトン（環状スルホン酸エステル）を含んでいることが好ましい。電池の化学的安定性が向上するからである。スルトンとしては、例えばプロパンスルトン、プロペンスルトンが挙げられる。   The solvent additive preferably contains sultone (cyclic sulfonic acid ester). This is because the chemical stability of the battery is improved. Examples of sultone include propane sultone and propene sultone.

さらに、溶媒は、酸無水物を含んでいることが好ましい。電解液の化学的安定性が向上するからである。酸無水物としては、例えば、プロパンジスルホン酸無水物が挙げられる。   Furthermore, it is preferable that the solvent contains an acid anhydride. This is because the chemical stability of the electrolytic solution is improved. Examples of the acid anhydride include propanedisulfonic acid anhydride.

電解質塩は、例えば、リチウム塩などの軽金属塩のいずれか１種類以上含むことができる。リチウム塩として、例えば、次の材料があげられる。六フッ化リン酸リチウム（ＬｉＰＦ６）、四フッ化ホウ酸リチウム（ＬｉＢＦ４）などが挙げられる。 The electrolyte salt can contain, for example, any one or more of light metal salts such as lithium salts. Examples of the lithium salt include the following materials. Examples thereof include lithium hexafluorophosphate (LiPF 6 ) and lithium tetrafluoroborate (LiBF 4 ).

電解質塩の含有量は、溶媒に対して０．５ｍｏｌ／ｋｇ以上２．５ｍｏｌ／ｋｇ以下であることが好ましい。高いイオン伝導性が得られるからである。   The content of the electrolyte salt is preferably 0.5 mol / kg or more and 2.5 mol / kg or less with respect to the solvent. This is because high ionic conductivity is obtained.

［ラミネートフィルム型リチウムイオン二次電池の製造方法］
最初に上記した正極材を用い正極電極を作製する。まず、正極活物質と、必要に応じて結着剤、導電助剤などを混合し正極合剤としたのち、有機溶剤に分散させ正極合剤スラリーとする。続いて、ナイフロールまたはダイヘッドを有するダイコーターなどのコーティング装置で正極集電体に合剤スラリーを塗布し、熱風乾燥させて正極活物質層を得る。最後に、ロールプレス機などで正極活物質層を圧縮成型する。この時、加熱を行っても良い。また、圧縮、加熱を複数回繰り返しても良い。 [Production method of laminated film type lithium ion secondary battery]
First, a positive electrode is manufactured using the positive electrode material described above. First, a positive electrode active material and, if necessary, a binder, a conductive additive and the like are mixed to form a positive electrode mixture, and then dispersed in an organic solvent to form a positive electrode mixture slurry. Subsequently, the mixture slurry is applied to the positive electrode current collector with a coating apparatus such as a die coater having a knife roll or a die head, and dried with hot air to obtain a positive electrode active material layer. Finally, the positive electrode active material layer is compression molded with a roll press or the like. At this time, heating may be performed. Further, compression and heating may be repeated a plurality of times.

次に、上記したリチウムイオン二次電池用負極１０の作製と同様の作業手順を用い、負極集電体に負極活物質層を形成し負極を作製する。   Next, a negative electrode is produced by forming a negative electrode active material layer on the negative electrode current collector, using the same operation procedure as the production of the negative electrode 10 for a lithium ion secondary battery described above.

正極及び負極を上記した同様の作製手順により作製する。この場合、正極及び負極集電体の両面にそれぞれの活物質層を形成する。この時、どちらの電極においても両面部の活物質塗布長がずれていても良い（図１を参照）。   The positive electrode and the negative electrode are manufactured by the same manufacturing procedure as described above. In this case, each active material layer is formed on both surfaces of the positive electrode and the negative electrode current collector. At this time, the active material application length of both surface portions may be shifted in either electrode (see FIG. 1).

続いて、電解液を調整する。続いて、超音波溶接などにより、正極集電体に正極リード２２を取り付けると共に、負極集電体に負極リード２３を取り付ける。続いて、正極と負極とをセパレータを介して積層、又は巻回させて巻回電極体を作成し、その最外周部に保護テープを接着させる（図３を参照）。次に、扁平な形状となるように巻回体を成型する。続いて、折りたたんだフィルム状の外装部材２５の間に巻回電極体を挟み込んだ後、熱融着法により外装部材の絶縁部同士を接着させ、一方向のみ解放状態にて、巻回電極体を封入する。正極リード２２、及び負極リード２３と外装部材２５の間に密着フィルム２４を挿入する。解放部から上記調整した電解液を所定量投入し、真空含浸を行う。含浸後、解放部を真空熱融着法により接着させる。   Subsequently, the electrolytic solution is adjusted. Subsequently, the positive electrode lead 22 is attached to the positive electrode current collector and the negative electrode lead 23 is attached to the negative electrode current collector by ultrasonic welding or the like. Subsequently, a positive electrode and a negative electrode are laminated or wound via a separator to form a wound electrode body, and a protective tape is adhered to the outermost periphery (see FIG. 3). Next, the wound body is molded so as to have a flat shape. Subsequently, after the wound electrode body is sandwiched between the folded film-shaped exterior member 25, the insulating portions of the exterior member are bonded to each other by a heat fusion method, and the wound electrode body is released in only one direction. Enclose. The adhesion film 24 is inserted between the positive electrode lead 22 and the negative electrode lead 23 and the exterior member 25. A predetermined amount of the adjusted electrolytic solution is introduced from the release portion, and vacuum impregnation is performed. After impregnation, the release part is bonded by a vacuum heat fusion method.

以上のようにして、ラミネートフィルム型二次電池２０を製造することができる。   The laminated film type secondary battery 20 can be manufactured as described above.

以下、本発明の実施例及び比較例を示して本発明をより具体的に説明するが、本発明はこれら実施例に限定されるものではない。   EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples of the present invention, but the present invention is not limited to these examples.

（実施例１−１）
以下の手順により、図３に示したラミネートフィルム型の二次電池２０を作製した。 (Example 1-1)
The laminate film type secondary battery 20 shown in FIG. 3 was produced by the following procedure.

最初に正極を作製した。正極活物質はリチウムコバルト複合酸化物であるＬｉＣｏＯ２を９５質量部と、正極導電助剤（アセチレンブラック）２．５質量部と、正極結着剤（ポリフッ化ビニリデン：ＰＶＤＦ）２．５質量部とを混合し正極合剤とした。続いて正極合剤を有機溶剤（Ｎ−メチル−２−ピロリドン：ＮＭＰ）に分散させてペースト状のスラリーとした。続いてダイヘッドを有するコーティング装置で正極集電体の両面にスラリーを塗布し、熱風式乾燥装置で乾燥した。この時、正極集電体は厚み１５μｍのものを用いた。最後にロールプレスで圧縮成型を行った。 First, a positive electrode was produced. The positive electrode active material is 95 parts by mass of LiCoO 2 which is a lithium cobalt composite oxide, 2.5 parts by mass of a positive electrode conductive additive (acetylene black), and 2.5 parts by mass of a positive electrode binder (polyvinylidene fluoride: PVDF). Were mixed to obtain a positive electrode mixture. Subsequently, the positive electrode mixture was dispersed in an organic solvent (N-methyl-2-pyrrolidone: NMP) to obtain a paste slurry. Subsequently, the slurry was applied to both surfaces of the positive electrode current collector with a coating apparatus having a die head, and dried with a hot air drying apparatus. At this time, a positive electrode current collector having a thickness of 15 μm was used. Finally, compression molding was performed with a roll press.

次に、負極を作製した。負極活物質を作製するため、まず、金属ケイ素と二酸化ケイ素を混合した原料を反応炉へ設置し、１０Ｐａの真空下で堆積し、十分に冷却した後、堆積物を取出しボールミルで粉砕した。粒径を調整した後、熱ＣＶＤを行うことで炭素被膜を得た。このとき、熱ＣＶＤにはロータリーキルンタイプの反応炉を用い、炭素源としてメタンガス、炉内の温度を１０００℃、圧力を１ａｔｍ、ＣＶＤ時間を６時間とした。   Next, a negative electrode was produced. In order to produce a negative electrode active material, first, a raw material in which metallic silicon and silicon dioxide were mixed was placed in a reaction furnace, deposited under a vacuum of 10 Pa, sufficiently cooled, and then the deposit was taken out and pulverized with a ball mill. After adjusting the particle size, a carbon film was obtained by performing thermal CVD. At this time, a rotary kiln type reactor was used for thermal CVD, methane gas as the carbon source, the temperature in the furnace was 1000 ° C., the pressure was 1 atm, and the CVD time was 6 hours.

作製した粉末はプロピレンカーボネート及びエチレンカーボネートの１：１混合溶媒（電解質塩として、六フッ化リン酸リチウム（ＬｉＰＦ６）を１．３ｍｏｌ／ｋｇ含む）中で電気化学法を用いバルク改質を行った。得られた材料は炭酸雰囲気下で乾燥処理を行った。 The prepared powder was subjected to bulk modification using an electrochemical method in a 1: 1 mixed solvent of propylene carbonate and ethylene carbonate (containing 1.3 mol / kg of lithium hexafluorophosphate (LiPF 6 ) as an electrolyte salt). It was. The obtained material was dried under a carbon dioxide atmosphere.

続いて、上記のようにして得られた粉末の一部を取り出し、テフロン（登録商標）製ビーカーに入れ、さらにイオン交換水、エタノールを加えて、テフロン（登録商標）製撹拌棒でよく撹拌した。その後、フッ化水素酸を加えて撹拌し、硝酸を加え、適時イオン交換水を追加し、さらに硝酸を加えて３時間放置した。その後、得られた黒色溶液をろ過することで、単離した炭素被膜をろ取した。続いて、単離した炭素被膜を水で洗浄し、さらにエタノールで洗浄後、２００℃で１０時間真空乾燥した。このようにして単離した炭素被膜の多点ＢＥＴ法による比表面積及び１．０ｇ／ｃｍ３の密度に圧縮した時の圧縮抵抗率を測定した。 Subsequently, a part of the powder obtained as described above was taken out, placed in a Teflon (registered trademark) beaker, further ion-exchanged water and ethanol were added, and the mixture was thoroughly stirred with a Teflon (registered trademark) stir bar. . Thereafter, hydrofluoric acid was added and stirred, nitric acid was added, ion-exchanged water was added as appropriate, nitric acid was further added, and the mixture was allowed to stand for 3 hours. Then, the isolated carbon film was filtered by filtering the obtained black solution. Subsequently, the isolated carbon film was washed with water, further washed with ethanol, and then vacuum-dried at 200 ° C. for 10 hours. The specific surface area by the multipoint BET method of the carbon coating thus isolated and the compression resistivity when compressed to a density of 1.0 g / cm 3 were measured.

その結果、単離した炭素被膜の多点ＢＥＴ法による比表面積は１８０ｍ２／ｇ、１．０ｇ／ｃｍ３の密度に圧縮した時の圧縮抵抗率は８．０×１０−３Ω・ｃｍであった。 In result, the compression resistance when the specific surface area by a multipoint BET method of the isolated carbon film compressed to a density of 180m 2 /g,1.0g/cm 3 is 8.0 × 10 -3 Ω · cm there were.

続いて、負極活物質と負極結着剤の前駆体（ポリアミック酸）と導電助剤１（鱗片状黒鉛）と導電助剤２（アセチレンブラック）とを８０：８：１０：２の乾燥質量比で混合した後、水で希釈してペースト状の負極合剤スラリーとした。この場合には、ポリアクリル酸の溶媒として水を用いた。続いて、コーティング装置で負極集電体の両面に負極合剤スラリーを塗布してから乾燥させた。この負極集電体としては、電解銅箔（厚さ＝１５μｍ）を用いた。最後に、真空雰囲気中で９０℃×１時間乾燥した。   Subsequently, the negative active material, the precursor of the negative electrode binder (polyamic acid), the conductive additive 1 (flaky graphite), and the conductive additive 2 (acetylene black) are in a dry mass ratio of 80: 8: 10: 2. Then, the mixture was diluted with water to obtain a paste-like negative electrode mixture slurry. In this case, water was used as a solvent for polyacrylic acid. Subsequently, the negative electrode mixture slurry was applied to both surfaces of the negative electrode current collector with a coating apparatus and then dried. As this negative electrode current collector, an electrolytic copper foil (thickness = 15 μm) was used. Finally, it was dried in a vacuum atmosphere at 90 ° C. for 1 hour.

次に、溶媒（４−フルオロ−１，３−ジオキソラン−２−オン（ＦＥＣ）、エチレンカーボネート（ＥＣ）及びジメチルカーボネート（ＤＭＣ））を混合したのち、電解質塩（六フッ化リン酸リチウム：ＬｉＰＦ６）を溶解させて電解液を調製した。この場合には、溶媒の組成を体積比でＦＥＣ：ＥＣ：ＤＭＣ＝１０：２０：７０とし、電解質塩の含有量を溶媒に対して１．２ｍｏｌ／ｋｇとした。 Next, after mixing a solvent (4-fluoro-1,3-dioxolan-2-one (FEC), ethylene carbonate (EC) and dimethyl carbonate (DMC)), an electrolyte salt (lithium hexafluorophosphate: LiPF) 6 ) was dissolved to prepare an electrolytic solution. In this case, the composition of the solvent was FEC: EC: DMC = 10: 20: 70 by volume ratio, and the content of the electrolyte salt was 1.2 mol / kg with respect to the solvent.

次に、以下のようにして二次電池を組み立てた。最初に正極集電体の一端にアルミリードを超音波溶接し、負極集電体にはニッケルリードを溶接した。続いて正極、セパレータ、負極、セパレータをこの順に積層し、長手方向に巻回させ巻回電極体を得た。その捲き終わり部分をＰＥＴ保護テープで固定した。セパレータは多孔性ポリプロピレンを主成分とするフィルムにより多孔性ポリエチレンを主成分とするフィルムに挟まれた積層フィルム１２μｍを用いた。続いて、外装部材間に電極体を挟んだのち、一辺を除く外周縁部同士を熱融着し、内部に電極体を収納した。外装部材はナイロンフィルム、アルミ箔、及びポリプロピレンフィルムが積層されたアルミラミネートフィルムを用いた。続いて、開口部から調整した電解液を注入し、真空雰囲気下で含浸した後、熱融着し封止した。   Next, a secondary battery was assembled as follows. First, an aluminum lead was ultrasonically welded to one end of the positive electrode current collector, and a nickel lead was welded to the negative electrode current collector. Subsequently, a positive electrode, a separator, a negative electrode, and a separator were laminated in this order and wound in the longitudinal direction to obtain a wound electrode body. The end portion was fixed with PET protective tape. As the separator, a laminated film of 12 μm sandwiched between a film mainly composed of porous polyethylene and a film mainly composed of porous polypropylene was used. Subsequently, after sandwiching the electrode body between the exterior members, the outer peripheral edges except for one side were heat-sealed, and the electrode body was housed inside. As the exterior member, an aluminum laminated film in which a nylon film, an aluminum foil, and a polypropylene film were laminated was used. Subsequently, the prepared electrolyte was injected from the opening, impregnated in a vacuum atmosphere, and then heat-sealed and sealed.

（実施例１−２〜実施例１−５、比較例１−１〜比較例１−２）
ＳｉＯｘで表わされるケイ素化合物において、酸素量を調整した以外は、実施例１−１と同様に、二次電池を作製した。 (Example 1-2 to Example 1-5, Comparative Example 1-1 to Comparative Example 1-2)
A secondary battery was fabricated in the same manner as in Example 1-1 except that the amount of oxygen in the silicon compound represented by SiOx was adjusted.

実施例１−１〜実施例１−５、比較例１−１〜比較例１−２における、ケイ素系活物質粒子はいずれも以下の物性を有していた。ケイ素系活物質粒子に含まれるケイ素化合物の２９Ｓｉ−ＭＡＳ−ＮＭＲによるピーク面積比Ａ／Ｂ＝０．６、（Ａ＋Ｂ）／Ｃ＝０．３２であった。また、ケイ素系活物質粒子のメディアン径Ｄ５０は５．１μｍであった。Ｘ線回折により得られるＳｉ（１１１）結晶面に起因する回折ピークの半値幅（２θ）は１．８５°であり、その結晶面Ｓｉ（１１１）に起因する結晶子サイズは４．６２ｎｍであった。 The silicon-based active material particles in Example 1-1 to Example 1-5 and Comparative Example 1-1 to Comparative Example 1-2 all had the following physical properties. The peak area ratios of 29 Si-MAS-NMR of the silicon compound contained in the silicon-based active material particles were A / B = 0.6 and (A + B) /C=0.32. Also, the median diameter D 50 of the silicon-based active material particle was 5.1 .mu.m. The full width at half maximum (2θ) of the diffraction peak attributable to the Si (111) crystal plane obtained by X-ray diffraction is 1.85 °, and the crystallite size attributable to the crystal plane Si (111) is 4.62 nm. It was.

また、実施例１−１〜実施例１−５、比較例１−１〜比較例１−２における、炭素被膜の含有率は５％、炭素被膜の平均厚さは１１０ｎｍ、炭素被膜の平均被覆率は９０％、炭素被膜の真密度は１．６ｇ／ｃｍ３であった。また、ラマンスペクトルの強度比Ｉ１３３０／Ｉ１５８０＝１．１であった。また、ＴＯＦ−ＳＩＭＳによって、ｙ＝２、３、４、ｚ＝２ｙ−３、２ｙ−１、２ｙ＋１であるＣｙＨｚ系化合物のフラグメントが検出された。また、ＴＯＦ−ＳＩＭＳによるＣ４Ｈ９の検出強度ＤとＣ３Ｈ５の検出強度Ｅの強度比Ｄ／Ｅ（Ｉｎｔ（Ｃ４Ｈ９／Ｃ３Ｈ５））＝０．８であった。 In Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-2, the carbon coating content was 5%, the average thickness of the carbon coating was 110 nm, and the average coating of the carbon coating. The rate was 90%, and the true density of the carbon coating was 1.6 g / cm 3 . Further, the intensity ratio of Raman spectrum was I 1330 / I 1580 = 1.1. Further, the TOF-SIMS, y = 2,3,4, fragment C y H z compounds which are z = 2y-3,2y-1,2y + 1 is detected. Further, the intensity ratio D / E (Int (C 4 H 9 / C 3 H 5 )) of the detection intensity D of C 4 H 9 and the detection intensity E of C 3 H 5 by TOF-SIMS was 0.8. .

また、単離した炭素被膜の多点ＢＥＴ法による比表面積は１８０ｍ２／ｇ、１．０ｇ／ｃｍ３の密度に圧縮した時の圧縮抵抗率は８．０×１０−３Ω・ｃｍであった。また、単離した炭素被膜の吸脱着等温線は、ＩＵＰＡＣ分類におけるＩＩ型の特徴を有していた。また、単離した炭素被膜を単位面積あたりの質量が０．１５ｇ／ｃｍ２となるように測定容器に仕込み、５０ＭＰａで加圧して圧縮した際の圧縮密度は１．１ｇ／ｃｍ３であった。 The compression resistance when compressed to a density of specific surface area by the multi-point BET method of the isolated carbon film 180m 2 /g,1.0g/cm 3 is 8.0 × encountered 10 -3 Ω · cm It was. Also, the adsorption and desorption isotherms of the isolated carbon coating had type II characteristics in the IUPAC classification. In addition, the compression density when the isolated carbon coating was charged in a measurement container so that the mass per unit area was 0.15 g / cm 2 and compressed by pressing at 50 MPa was 1.1 g / cm 3 . .

実施例１−１〜実施例１−５、比較例１−１〜比較例１−２の二次電池のサイクル特性（維持率％）、初回充放電特性（初期効率％）を調べたところ、表１に示した結果が得られた。   When the cycle characteristics (maintenance rate%) and the initial charge / discharge characteristics (initial efficiency%) of the secondary batteries of Example 1-1 to Example 1-5 and Comparative Example 1-1 to Comparative Example 1-2 were examined, The results shown in Table 1 were obtained.

サイクル特性については、以下のようにして調べた。最初に電池安定化のため２５℃の雰囲気下、２サイクル充放電を行い、２サイクル目の放電容量を測定した。続いて総サイクル数が１００サイクルとなるまで充放電を行い、その都度放電容量を測定した。最後に１００サイクル目の放電容量を２サイクル目の放電容量で割り（％表示のため×１００）、容量維持率を算出した。サイクル条件として、４．３Ｖに達するまで定電流密度、２．５ｍＡ／ｃｍ２で充電し、電圧に達した段階で４．３Ｖ定電圧で電流密度が０．２５ｍＡ／ｃｍ２に達するまで充電した。また放電時は２．５ｍＡ／ｃｍ２の定電流密度で電圧が３．０Ｖに達するまで放電した。 The cycle characteristics were examined as follows. First, in order to stabilize the battery, charge / discharge was performed for 2 cycles in an atmosphere at 25 ° C., and the discharge capacity at the second cycle was measured. Subsequently, charge and discharge were performed until the total number of cycles reached 100, and the discharge capacity was measured each time. Finally, the discharge capacity at the 100th cycle was divided by the discharge capacity at the 2nd cycle (because it is expressed in% × 100), and the capacity maintenance rate was calculated. As cycling conditions, a constant current density until reaching 4.3V, and charged at 2.5 mA / cm 2, the current density at 4.3V constant voltage at the stage of reaching the voltage charged to reach 0.25 mA / cm 2 . During discharging, discharging was performed at a constant current density of 2.5 mA / cm 2 until the voltage reached 3.0V.

初回充放電特性を調べる場合には、初回効率（％）＝（初回放電容量／初回充電容量）×１００を算出した。雰囲気温度は、サイクル特性を調べた場合と同様にした。充放電条件はサイクル特性の０．２倍で行った。すなわち、４．３Ｖに達するまで定電流密度、０．５ｍＡ／ｃｍ２で充電し、電圧が４．３Ｖに達した段階で４．３Ｖ定電圧で電流密度が０．０５ｍＡ／ｃｍ２に達するまで充電し、放電時は０．５ｍＡ／ｃｍ２の定電流密度で電圧が３．０Ｖに達するまで放電した。 When examining the initial charge / discharge characteristics, the initial efficiency (%) = (initial discharge capacity / initial charge capacity) × 100 was calculated. The ambient temperature was the same as when the cycle characteristics were examined. The charge / discharge conditions were 0.2 times the cycle characteristics. That is, a constant current density until reaching 4.3V, and charged at 0.5 mA / cm 2, at 4.3V constant voltage at the stage where the voltage reaches 4.3V until the current density reached 0.05 mA / cm 2 The battery was charged and discharged at a constant current density of 0.5 mA / cm 2 until the voltage reached 3.0V.

尚、下記表１から表９に示される維持率及び初回効率は、天然黒鉛（例えば、メディアン径２０μｍ）等の炭素系活物質を含有せず、炭素被膜を有するケイ素化合物のみを負極活物質として使用した場合の維持率及び初回効率、すなわち、ケイ素化合物の維持率及び初回効率を示す。これにより、ケイ素化合物の変化（酸素量、結晶性、メディアン径の変化など）又は炭素被膜の変化（含有率、組成など）のみに依存した維持率及び初回効率の変化を測定することができた。   The maintenance ratios and initial efficiency shown in Tables 1 to 9 below do not contain a carbon-based active material such as natural graphite (for example, a median diameter of 20 μm), and only a silicon compound having a carbon coating is used as the negative electrode active material. The maintenance rate and initial efficiency when used, that is, the maintenance rate and initial efficiency of the silicon compound are shown. As a result, it was possible to measure changes in retention rate and initial efficiency that depended solely on changes in silicon compounds (changes in oxygen content, crystallinity, median diameter, etc.) or changes in carbon coating (contents, composition, etc.). .

Figure 0006448525
Figure 0006448525

表１に示すように、ＳｉＯｘで表わされるケイ素化合物において、ｘの値が、０．５≦ｘ≦１．６の範囲外の場合、電池特性が悪化した。例えば、比較例１−１に示すように、酸素が十分にない場合（ｘ＝０．３）初回効率が向上するが、容量維持率が著しく悪化する。一方、比較例１−２に示すように、酸素量が多い場合（ｘ＝１．８）導電性の低下が生じ維持率、初回効率とも低下し、測定不可となった。   As shown in Table 1, in the silicon compound represented by SiOx, when the value of x was outside the range of 0.5 ≦ x ≦ 1.6, the battery characteristics deteriorated. For example, as shown in Comparative Example 1-1, when there is not enough oxygen (x = 0.3), the initial efficiency is improved, but the capacity retention rate is significantly deteriorated. On the other hand, as shown in Comparative Example 1-2, when the amount of oxygen was large (x = 1.8), the conductivity decreased and both the maintenance rate and the initial efficiency decreased, and measurement was impossible.

（実施例２−１〜実施例２−３、比較例２−１〜比較例２−３）
ケイ素化合物の表面に被覆する炭素被膜の状態を変化させ、炭素被膜を単離して測定した１．０ｇ／ｃｍ３の密度に圧縮した時の圧縮抵抗率及び単位面積あたりの質量が０．１５ｇ／ｃｍ２となるように測定容器に仕込んだ後に、５０ＭＰａで加圧して圧縮した場合の圧縮密度を変化させたことを除き、実施例１−３と同様に、二次電池の製造を行った。なお、ケイ素化合物から炭素被膜を単離して測定した場合の、炭素被膜の圧縮抵抗率と圧縮密度は、ＣＶＤ温度、時間及びＣＶＤ時の粉末材料（ケイ素化合物粉体）の攪拌度およびＣＶＤガス流量を調節することによって行った。 (Example 2-1 to Example 2-3, Comparative Example 2-1 to Comparative Example 2-3)
The state of the carbon film coated on the surface of the silicon compound was changed, and the compression resistivity and the mass per unit area when the carbon film was isolated and measured to a density of 1.0 g / cm 3 were 0.15 g / A secondary battery was manufactured in the same manner as in Example 1-3, except that the compression density was changed after being charged into a measurement container so as to be cm 2 and then pressurized and compressed at 50 MPa. In addition, the compression resistivity and compression density of the carbon coating when measured by isolating the carbon coating from the silicon compound are the CVD temperature, time, degree of stirring of the powder material (silicon compound powder) during CVD, and the CVD gas flow rate. Was done by adjusting.

実施例２−１〜２−３、比較例２−１〜比較例２−３の二次電池のサイクル特性及び初回充放電特性を調べたところ、表２に示した結果が得られた。   When the cycle characteristics and the initial charge / discharge characteristics of the secondary batteries of Examples 2-1 to 2-3 and Comparative examples 2-1 to 2-3 were examined, the results shown in Table 2 were obtained.

Figure 0006448525
Figure 0006448525

表２に示すように、炭素被膜の密度が１．０ｇ／ｃｍ３の時の圧縮抵抗率が１．０×１０−３Ω・ｃｍ以上１．０Ω・ｃｍ以下である場合は、充放電時の電子伝導性が適当なため、Ｌｉの析出等が起こりにくいと同時に負極の導電性がより均一となりやすく、維持率、初回効率が向上する。また、炭素被膜の上記圧縮密度が１．０ｇ／ｃｍ３以上１．８ｇ／ｃｍ３以下である場合は、ケイ素化合物表面で結着剤が適切に吸着し、初回効率および容量維持率が向上する。 As shown in Table 2, when the compression resistivity when the density of the carbon coating is 1.0 g / cm 3 is 1.0 × 10 −3 Ω · cm or more and 1.0 Ω · cm or less, at the time of charge / discharge Therefore, the deposition of Li or the like is unlikely to occur, and the conductivity of the negative electrode tends to be more uniform, so that the maintenance ratio and the initial efficiency are improved. Further, the compressed density of the carbon film is the case is less than 1.0 g / cm 3 or more 1.8 g / cm 3, the binder is properly adsorbed at the surface silicon compound, thereby improving initial efficiency and capacity retention rate .

（実施例３−１〜実施例３−８、比較例３−１〜比較例３−２）
ケイ素系活物質粒子に対する炭素被膜の含有率、ケイ素化合物表面における炭素被膜の平均厚さ、ケイ素化合物表面における炭素被膜の平均被覆率、ケイ素化合物表面における平均真密度、単離した炭素被膜の吸脱着等温線のＩＵＰＡＣ分類、単離した炭素被膜の比表面積を変化させた以外は、実施例１−３と同様に二次電池の製造を行った。炭素被膜の含有率、平均厚さ、平均被覆率、平均真密度、単離した炭素被膜の吸脱着等温線のＩＵＰＡＣ分類、単離した炭素被膜の比表面積の変化はＣＶＤ温度、時間およびＣＶＤ時のケイ素化合物粉体の撹拌度を調節することで制御可能である。 (Example 3-1 to Example 3-8, Comparative Example 3-1 to Comparative Example 3-2)
Content ratio of carbon coating to silicon-based active material particles, average thickness of carbon coating on silicon compound surface, average coverage of carbon coating on silicon compound surface, average true density on silicon compound surface, adsorption / desorption of isolated carbon coating A secondary battery was manufactured in the same manner as in Example 1-3 except that the IUPAC classification of the isotherm and the specific surface area of the isolated carbon film were changed. Content of carbon film, average thickness, average coverage, average true density, IUPAC classification of adsorption / desorption isotherm of isolated carbon film, change in specific surface area of isolated carbon film depends on CVD temperature, time and CVD It can be controlled by adjusting the degree of stirring of the silicon compound powder.

実施例３−１〜実施例３−８、比較例３−１〜比較例３−２の二次電池のサイクル特性及び初回充放電特性を調べたところ、表６に示した結果が得られた。   When the cycle characteristics and initial charge / discharge characteristics of the secondary batteries of Example 3-1 to Example 3-8 and Comparative Example 3-1 to Comparative Example 3-2 were examined, the results shown in Table 6 were obtained. .

Figure 0006448525
Figure 0006448525

表３からわかるように、単離した炭素被膜の比表面積が、５ｍ２／ｇ以上１０００ｍ２／ｇ以下である実施例３−１〜実施例３−８では、比較例３−１、比較例３−２よりも良好な電池特性が得られる。これは、単離した炭素被膜の比表面積が５ｍ２／ｇを下回る場合は電解液の含浸性が低下し、単離した炭素被膜の比表面積が１０００ｍ２／ｇを超える場合は、結着剤の過剰な吸着により、結着性が低下し、電池特性が悪化するためである。 As can be seen from Table 3, in Example 3-1 to Example 3-8 in which the specific surface area of the isolated carbon coating is 5 m 2 / g or more and 1000 m 2 / g or less, Comparative Example 3-1 and Comparative Example Battery characteristics better than 3-2 are obtained. This is because when the specific surface area of the isolated carbon film is less than 5 m 2 / g, the impregnating property of the electrolytic solution is lowered, and when the specific surface area of the isolated carbon film exceeds 1000 m 2 / g, the binder is used. This is because, due to excessive adsorption, the binding property is lowered and the battery characteristics are deteriorated.

また、実施例において炭素被膜の含有率が０．１％から２５％、炭素被膜の厚さが５ｎｍ以上５００ｎｍ以下、平均被覆率が３０％以上、炭素被膜の真密度が１．２ｇ／ｃｍ３以上１．９ｇ／ｃｍ３以下、及び単離した炭素被膜のＩＵＰＡＣ吸脱着等温線の分類がＩＩ型或いはＩＩＩ型という条件をすべて満たした実施例１−３、実施例３−３〜実施例３−６は最も良い電池特性が得られた。一方でこれらの条件を１つ以上満たしていない場合、実施例１−３、実施例３−３〜実施例３−６より若干電池特性が悪化した。 In the examples, the carbon film content is 0.1% to 25%, the carbon film thickness is 5 nm to 500 nm, the average coverage is 30%, and the true density of the carbon film is 1.2 g / cm 3. Examples 1-3 and Examples 3-3 to 3 in which 1.9 g / cm 3 or less of the above and the IUPAC adsorption / desorption isotherm classification of the isolated carbon coating satisfy all the conditions of type II or type III The best battery characteristic was obtained for -6. On the other hand, when one or more of these conditions were not satisfied, the battery characteristics were slightly worse than those of Examples 1-3 and Examples 3-3 to 3-6.

（実施例４−１〜実施例４−６）
ケイ素化合物内のＳｉ成分とＳｉＯ２成分の比（Ｓｉとシリカの比）及び不均化度を変化させたことを除き、実施例１−３と同様に、二次電池の製造を行った。Ｓｉ成分とＳｉＯ２成分の比は、ＳｉＯ作成時の金属ケイ素およびシリカの仕込み量を変更させることによって、実施例４−１〜実施例４−６で変化させた。また、ケイ素化合物（ＳｉＯｘ）において、２９Ｓｉ−ＭＡＳ−ＮＭＲ スペクトルから得られるケミカルシフト値として、−２０〜−７４ｐｐｍで与えられるアモルファスシリコン（ａ−Ｓｉ）領域のピーク面積Ａと−７５〜−９４ｐｐｍで与えられる結晶性シリコン（ｃ−Ｓｉ）領域のピーク面積Ｂとの比率Ａ／Ｂは熱処理によって不均化度を制御することによって調整した。 (Example 4-1 to Example 4-6)
A secondary battery was manufactured in the same manner as in Example 1-3, except that the ratio of Si component to SiO 2 component in the silicon compound (ratio of Si to silica) and the degree of disproportionation were changed. The ratio of the Si component to the SiO 2 component was changed in Examples 4-1 to 4-6 by changing the amounts of metal silicon and silica charged at the time of creating SiO. Further, in the silicon compound (SiO x ), as the chemical shift value obtained from the 29 Si-MAS-NMR spectrum, the peak area A of the amorphous silicon (a-Si) region given by −20 to −74 ppm and −75 to − The ratio A / B with the peak area B of the crystalline silicon (c-Si) region given at 94 ppm was adjusted by controlling the disproportionation degree by heat treatment.

実施例４−１〜実施例４−６の二次電池のサイクル特性及び初回充放電特性を調べたところ、表４に示した結果が得られた。   When the cycle characteristics and the initial charge / discharge characteristics of the secondary batteries of Example 4-1 to Example 4-6 were examined, the results shown in Table 4 were obtained.

Figure 0006448525
Figure 0006448525

表４からわかるように、５．０≧Ａ／Ｂ≧０．０１、６．０≧（Ａ＋Ｂ）／Ｃ≧０．０２の範囲を満たす場合（実施例１−３、４−３、４−４）、維持率、初回効率ともに良い特性となった。ａ−Ｓｉ成分が増加すると初回効率が低下するが、維持率は向上する。そのバランスが、５．０≧Ａ／Ｂ≧０．０１の範囲で保たれるためである。また、Ｓｉ成分とＳｉＯ２成分の比（Ａ＋Ｂ）／Ｃが６以下であれば、Ｌｉ挿入に伴う膨張を小さく抑制できるため、維持率が向上する。また、（Ａ＋Ｂ）／Ｃが０．０２以上であれば、導電性が向上し、維持率、初回効率ともに向上する。５．０≧Ａ／Ｂ≧０．０１のみを満たす場合（実施例４−１、４−６）では、Ａ／Ｂ及び（Ａ＋Ｂ）／Ｃの上記範囲を両方とも満たす場合に比べ、維持率が若干低下する。６．０≧（Ａ＋Ｂ）／Ｃ≧０．０２のみを満たす場合（実施例２−２、２−５）では、Ａ／Ｂ及び（Ａ＋Ｂ）／Ｃの上記範囲を両方とも満たす場合に比べ、維持率が若干低下する。 As can be seen from Table 4, when 5.0 ≧ A / B ≧ 0.01, 6.0 ≧ (A + B) /C≧0.02 is satisfied (Examples 1-3, 4-3, 4- 4) Both maintenance rate and initial efficiency were good characteristics. When the a-Si component is increased, the initial efficiency is lowered, but the maintenance ratio is improved. This is because the balance is maintained in the range of 5.0 ≧ A / B ≧ 0.01. Further, if the ratio (A + B) / C of the Si component to the SiO 2 component is 6 or less, expansion due to Li insertion can be suppressed to be small, so that the maintenance ratio is improved. Further, if (A + B) / C is 0.02 or more, the conductivity is improved, and both the maintenance ratio and the initial efficiency are improved. In the case where only 5.0 ≧ A / B ≧ 0.01 is satisfied (Examples 4-1 and 4-6), the maintenance ratio is compared to the case where both of the above ranges of A / B and (A + B) / C are satisfied. Decreases slightly. In the case where only 6.0 ≧ (A + B) /C≧0.02 is satisfied (Examples 2-2 and 2-5), compared to the case where both the above ranges of A / B and (A + B) / C are satisfied, The maintenance rate is slightly reduced.

（実施例５−１〜実施例５−５）
ケイ素化合物の結晶性を変化させた他は、実施例１−３と同様に二次電池の製造を行った。結晶性の変化は非大気雰囲気下の熱処理で制御可能である。実施例５−１では結晶子サイズを１．５４２と算出しているが、解析ソフトを用いフィッティングした結果であり、実質的にピークは得られていない。よって実施例５−１のケイ素化合物は実質的に非晶質であると言える。 (Example 5-1 to Example 5-5)
A secondary battery was manufactured in the same manner as in Example 1-3 except that the crystallinity of the silicon compound was changed. The change in crystallinity can be controlled by heat treatment in a non-atmospheric atmosphere. In Example 5-1, the crystallite size is calculated to be 1.542, but it is a result of fitting using analysis software, and a peak is not substantially obtained. Therefore, it can be said that the silicon compound of Example 5-1 is substantially amorphous.

実施例５−１〜５−５の二次電池のサイクル特性及び初回充放電特性を調べたところ、表５に示した結果が得られた。   When the cycle characteristics and initial charge / discharge characteristics of the secondary batteries of Examples 5-1 to 5-5 were examined, the results shown in Table 5 were obtained.

Figure 0006448525
Figure 0006448525

表５からわかるように、ケイ素化合物の結晶性を変化させたところ、それらの結晶性に応じて容量維持率及び初回効率が変化した。特にＳｉ（１１１）面に起因する結晶子サイズ７．５ｎｍ以下の低結晶性材料で高い維持率が可能となる。特に非結晶領域では最も良い維持率が得られる。また、初期効率は結晶性が低くなるにつれて若干低下するが、問題とならない程度の初期効率が得られた。   As can be seen from Table 5, when the crystallinity of the silicon compound was changed, the capacity retention ratio and the initial efficiency changed according to the crystallinity. In particular, a high retention rate is possible with a low crystalline material having a crystallite size of 7.5 nm or less due to the Si (111) plane. In particular, the best maintenance ratio can be obtained in the amorphous region. Further, the initial efficiency was slightly lowered as the crystallinity was lowered, but an initial efficiency of a level not causing a problem was obtained.

（実施例６−１〜６−３）
ケイ素化合物の表面の炭素被膜の状態を変化させ、炭素被膜のラマンスペクトル分析における、１３３０ｃｍ−１と１５８０ｃｍ−１の散乱ピークの強度比Ｉ１３３０／Ｉ１５８０を変化させたこと除き、実施例１−３と同様に、二次電池の製造を行った。なお、散乱ピークの強度比Ｉ１３３０／Ｉ１５８０は、ＣＶＤ時の温度およびガス圧力を変化させることによって行った。 (Examples 6-1 to 6-3)
The state of the carbon coating on the surface of the silicon compound is varied, except that in the Raman spectrum analysis of carbon film, changing the intensity ratio I 1330 / I 1580 of the scattering peak of 1330 cm -1 and 1580 cm -1, Example 1 In the same manner as in Example 3, a secondary battery was manufactured. The scattering peak intensity ratio I 1330 / I 1580 was changed by changing the temperature and gas pressure during CVD.

実施例６−１〜実施例６−３の二次電池のサイクル特性及び初回充放電特性を調べたところ、表６に示した結果が得られた。   When the cycle characteristics and the initial charge / discharge characteristics of the secondary batteries of Example 6-1 to Example 6-3 were examined, the results shown in Table 6 were obtained.

Figure 0006448525
Figure 0006448525

表６に示すように、ラマンスペクトルにおける、散乱ピークの強度比Ｉ１３３０／Ｉ１５８０が２．０未満である場合は、表面にＩ１３３０に由来する乱雑な結合様式をもつ炭素成分が少なく、電子伝導性が高いため、維持率、初回効率が向上する。また、Ｉ１３３０／Ｉ１５８０が０．７より大きい場合は、表面にＩ１５８０に由来する黒鉛等の炭素成分が少なく、イオン電導性及び炭素被膜のケイ素化合物のＬｉ挿入に伴う膨張への追随性が向上し、容量維持率が向上する。 As shown in Table 6, when the intensity ratio I 1330 / I 1580 of the scattering peak in the Raman spectrum is less than 2.0, the surface has few carbon components having a messy bonding mode derived from I 1330 , and the electron Since the conductivity is high, the maintenance rate and initial efficiency are improved. In addition, when I 1330 / I 1580 is larger than 0.7, there are few carbon components such as graphite derived from I 1580 on the surface, and ion conductivity and followability to expansion associated with insertion of Li in the silicon compound of the carbon coating. And the capacity maintenance rate is improved.

（実施例７−１〜実施例７−５、比較例７−１）
ケイ素化合物表面の炭素被膜の状態を調整したこと以外は、実施例１−３と同様に、二次電池を作製した。すなわち、実施例７−１〜実施例７−５では、ＴＯＦ−ＳＩＭＳによって炭素被膜から検出されるＣｙＨｚフラグメント、ＴＯＦ−ＳＩＭＳにおけるＣ４Ｈ９の検出強度ＤとＣ３Ｈ５の検出強度Ｅの強度比Ｄ／Ｅを変化させた。この場合、ケイ素化合物へのＣＶＤの際に用いるガス種、ＣＶＤ温度、及びＣＶＤ後処理温度を調整している。また、比較例７−１では炭素被膜の被覆を行わなかった。 (Example 7-1 to Example 7-5, Comparative Example 7-1)
A secondary battery was produced in the same manner as in Example 1-3 except that the state of the carbon coating on the silicon compound surface was adjusted. That is, in Example 7-1 to Example 7-5, the C y H z fragment detected from the carbon film by TOF-SIMS, the detection intensity D of C 4 H 9 and the detection of C 3 H 5 in TOF-SIMS The intensity ratio D / E of the intensity E was changed. In this case, the gas type, the CVD temperature, and the post-CVD temperature used for CVD of the silicon compound are adjusted. In Comparative Example 7-1, the carbon coating was not applied.

実施例７−１〜７−５、比較例７−１の二次電池のサイクル特性及び初回充放電特性を調べたところ、表７に示した結果が得られた。   When the cycle characteristics and the initial charge / discharge characteristics of the secondary batteries of Examples 7-1 to 7-5 and Comparative example 7-1 were examined, the results shown in Table 7 were obtained.

Figure 0006448525
Figure 0006448525

表７に示すように、ＣｙＨｚ系化合物のフラグメントが検出された場合、及び２．５≧Ｄ／Ｅ≧０．３の関係を満たす場合は、電池特性が向上した。また、比較例７−１のように、炭素被膜が無い場合は、負極での電気伝導性が悪化するため、維持率、初回効率が悪化する。また、６≧ｙ≧２、２ｙ＋２≧ｚ≧２ｙ−２の範囲を満たすＣｙＨｚ系化合物のフラグメントが検出された場合、電池特性が向上した。特に、ｙの値が小さい場合、すなわち、ｙ＝２、３、４のＣｙＨｚ系化合物のフラグメントのみが検出される場合、電池特性がより向上した。 As shown in Table 7, when the fragment of the C y H z compound was detected and when the relationship of 2.5 ≧ D / E ≧ 0.3 was satisfied, the battery characteristics were improved. In addition, as in Comparative Example 7-1, when there is no carbon coating, the electrical conductivity at the negative electrode is deteriorated, so that the maintenance ratio and the initial efficiency are deteriorated. Moreover, when the fragment of the C y H z compound satisfying the range of 6 ≧ y ≧ 2, 2y + 2 ≧ z ≧ 2y−2 was detected, the battery characteristics were improved. In particular, when the value of y is small, that is, when only fragments of C y H z compounds with y = 2, 3, and 4 are detected, the battery characteristics are further improved.

（実施例８−１〜８−５）
ケイ素化合物のメディアン径を調節した他は、実施例１−３と同様に二次電池を製造した。メディアン径の調節はケイ素化合物の製造工程における粉砕時間、分級条件を変化させることによって行った。実施例８−１〜８−５の二次電池のサイクル特性、初回充放電特性を調べたところ、表８に示した結果が得られた。 (Examples 8-1 to 8-5)
A secondary battery was manufactured in the same manner as in Example 1-3 except that the median diameter of the silicon compound was adjusted. The median diameter was adjusted by changing the grinding time and classification conditions in the silicon compound production process. When the cycle characteristics and the initial charge / discharge characteristics of the secondary batteries of Examples 8-1 to 8-5 were examined, the results shown in Table 8 were obtained.

Figure 0006448525
Figure 0006448525

表８からわかるように、ケイ素化合物のメディアン径を変化させたところ、それに応じて維持率および初回効率が変化した。実施例８−２〜８−４に示すように、ケイ素化合物粒子のメディアン径が０．５μｍ〜２０μｍであると容量維持率がより高くなった。特にメディアン径が０．５μｍ以上１２μｍ以下の場合、維持率の向上がみられた。   As can be seen from Table 8, when the median diameter of the silicon compound was changed, the maintenance ratio and the initial efficiency changed accordingly. As shown in Examples 8-2 to 8-4, the capacity retention rate was higher when the median diameter of the silicon compound particles was 0.5 μm to 20 μm. In particular, when the median diameter was 0.5 μm or more and 12 μm or less, the maintenance ratio was improved.

（実施例９−１〜９−２）
ケイ素化合物にＬｉドープを行うことで、ケイ素系活物質粒子の少なくとも一部にＬｉを含有させたこと以外は、実施例１−３と同様に、二次電池を作成した。実施例９−１では熱ドープ法を用いて、実施例９−２では電気化学的手法を用いてＬｉドープを行った。 (Examples 9-1 to 9-2)
A secondary battery was produced in the same manner as in Example 1-3, except that at least a part of the silicon-based active material particles contained Li by doping the silicon compound with Li. In Example 9-1, Li doping was performed using a thermal doping method, and in Example 9-2 using an electrochemical method.

実施例９−１〜９−２の二次電池のサイクル特性及び初回充放電特性を調べたところ、表９に示した結果が得られた。   When the cycle characteristics and the initial charge / discharge characteristics of the secondary batteries of Examples 9-1 to 9-2 were examined, the results shown in Table 9 were obtained.

Figure 0006448525
Figure 0006448525

表９からわかるように、ケイ素系活物質粒子にＬｉを含有させたことによって、維持率が向上した。また、実施例９−２のように、電気化学的改質法によりＬｉをケイ素系活物質粒子にドープした場合、初回効率が向上した。また、非水電解質二次電池とした場合の負極の初回効率が上昇するため、サイクル試験時の正極と負極のバランスずれが抑制され、維持率が向上する。   As can be seen from Table 9, the retention rate was improved by adding Li to the silicon-based active material particles. In addition, as in Example 9-2, when Li was doped into silicon-based active material particles by an electrochemical modification method, the initial efficiency was improved. In addition, since the initial efficiency of the negative electrode in the case of a nonaqueous electrolyte secondary battery is increased, a deviation in the balance between the positive electrode and the negative electrode during the cycle test is suppressed, and the maintenance ratio is improved.

（実施例１０−１〜実施例１０−６）
実施例１０−１〜実施例１０−６では、基本的に実施例１−３と同様に二次電池の製造を行ったが、負極活物質として、さらに、炭素系活物質（人造黒鉛と天然黒鉛を１：１の質量比で混合したもの）を加え、負極中のケイ素化合物及び炭素系活物質材の含有量の比（ケイ素化合物（ＳｉＯ材）の活物質全体に占める割合）を変化させ、その割合に応じて結着剤も変更した。実施例１０−１〜１０−３では、結着剤として、スチレンブタジエンゴム（表１０では、ＳＢＲと表記）とＣＭＣを混合したものを使用した。実施例１０−４〜１０−６では、結着剤として、ポリイミド（表１０では、ＰＩと表記）を使用した。 (Example 10-1 to Example 10-6)
In Example 10-1 to Example 10-6, a secondary battery was manufactured basically in the same manner as in Example 1-3. However, as a negative electrode active material, a carbon-based active material (artificial graphite and natural graphite was used). Graphite is mixed at a mass ratio of 1: 1), and the ratio of the content of the silicon compound and the carbon-based active material in the negative electrode (the ratio of the silicon compound (SiO material) to the entire active material) is changed. The binder was also changed according to the ratio. In Examples 10-1 to 10-3, a mixture of styrene butadiene rubber (indicated as SBR in Table 10) and CMC was used as the binder. In Examples 10-4 to 10-6, polyimide (indicated as PI in Table 10) was used as the binder.

（比較例１０−１）
本発明の負極活物質を含有せず、実施例１０−１〜実施例１０−６でも使用した炭素系活物質のみを負極活物質とし、リチウムニッケルコバルトアルミニウム複合酸化物を正極材として使用した他は、実施例１−３と同様に二次電池を製造した。 (Comparative Example 10-1)
Other than using the negative electrode active material of the present invention, using only the carbon-based active material used in Example 10-1 to Example 10-6 as the negative electrode active material, and using lithium nickel cobalt aluminum composite oxide as the positive electrode material Produced a secondary battery in the same manner as in Example 1-3.

実施例１０−１〜１０−６、比較例１０−１の二次電池のサイクル特性及び初回充放電特性を調べた。また、実施例１０−１〜１０−６、比較例１０−１の二次電池の電力容量密度（ｍＡｈ／ｃｍ３）を測定し、比較例１０−１の二次電池の電力容量密度を基準とした場合の、相対的な電力容量密度を各々の場合で算出した。これらの結果を表１０に示す。 The cycle characteristics and initial charge / discharge characteristics of the secondary batteries of Examples 10-1 to 10-6 and Comparative Example 10-1 were examined. Moreover, the power capacity density (mAh / cm < 3 >) of the secondary battery of Examples 10-1 to 10-6 and Comparative Example 10-1 was measured, and the power capacity density of the secondary battery of Comparative Example 10-1 was used as a reference. The relative power capacity density was calculated in each case. These results are shown in Table 10.

Figure 0006448525
Figure 0006448525

表１０からわかるように、ケイ素系活物質粒子の割合を増やすと負極の容量は増加するが、初回効率、維持率の低下がみられる。また、表１０中に示す相対電力容量密度は、上記のようにケイ素系活物質粒子の割合が０、かつＮＣＡ（リチウムニッケルコバルトアルミニウム複合酸化物）正極材と組み合わせ、電池での放電カットオフ電圧を２．５Ｖとした場合の電力容量密度（比較例１０−１）を基準としている。ケイ素系活物質粒子の割合を減らすと、初回効率、維持率は向上するが、電力容量密度が小さくなる。特に、比較例１０−１のように炭素系活物質のみを負極活物質として使用する場合、高い電力容量密度のリチウムイオン二次電池を得ることはできない。特に、ケイ素系活物質粒子の割合が５質量％以上であると、十分な電力容量密度の向上が見られる。   As can be seen from Table 10, when the ratio of the silicon-based active material particles is increased, the capacity of the negative electrode is increased, but the initial efficiency and the maintenance ratio are decreased. Moreover, the relative power capacity density shown in Table 10 is a combination of a silicon-based active material particle ratio of 0 and an NCA (lithium nickel cobalt aluminum composite oxide) positive electrode material as described above, and a discharge cutoff voltage in the battery. Is based on the power capacity density (Comparative Example 10-1). If the ratio of the silicon-based active material particles is reduced, the initial efficiency and the maintenance rate are improved, but the power capacity density is reduced. In particular, when only the carbon-based active material is used as the negative electrode active material as in Comparative Example 10-1, a lithium ion secondary battery having a high power capacity density cannot be obtained. In particular, when the ratio of the silicon-based active material particles is 5% by mass or more, a sufficient improvement in power capacity density is observed.

（実施例１１−１〜実施例１１−８）
負極活物質層中の炭素系活物質の平均粒径Ｇ（炭素活物質粒子のメディアン径Ｄ５０）とケイ素系活物質の平均粒径Ｆ（ケイ素系活物質粒子のメディアン径Ｄ５０）を変化させて、これらの比Ｇ／Ｆを変化させたことを除き、実施例１０−２と同様に、二次電池の製造を行った。 (Example 11-1 to Example 11-8)
The average particle diameter G of carbon-based active material in the negative electrode active material layer (median diameter D 50 of carbon active material particles) and the average particle diameter F of silicon-based active material (median diameter D 50 of silicon-based active material particles) are changed. Thus, a secondary battery was manufactured in the same manner as in Example 10-2 except that these ratios G / F were changed.

実施例１１−１〜１１−８の二次電池のサイクル特性及び初回充放電特性を調べたところ、表１１に示した結果が得られた。   When the cycle characteristics and the initial charge / discharge characteristics of the secondary batteries of Examples 11-1 to 11-8 were examined, the results shown in Table 11 were obtained.

Figure 0006448525
Figure 0006448525

表１１からわかるように、負極活物質層中の炭素系活物質粒子は、ケイ素系活物質粒子に対し同等以上の大きさであること、すなわち、Ｇ／Ｆ≧０．５であることが望ましい。膨張収縮するケイ素化合物が炭素系負極材に対して同等以下の大きさである場合、合材層の破壊を防止することができる。炭素系負極材がケイ素化合物に対して大きくなると、充電時の負極体積密度、初期効率が向上し、電池エネルギー密度が向上する。また、特に、２５≧Ｇ／Ｆ≧０．５の範囲を満たすことで、初回効率、及び維持率がより向上する。   As can be seen from Table 11, it is desirable that the carbon-based active material particles in the negative electrode active material layer have a size equal to or greater than that of the silicon-based active material particles, that is, G / F ≧ 0.5. . When the silicon compound that expands and contracts is equal to or smaller than that of the carbon-based negative electrode material, the composite material layer can be prevented from being broken. When the carbon-based negative electrode material is larger than the silicon compound, the negative electrode volume density and initial efficiency during charging are improved, and the battery energy density is improved. In particular, by satisfying the range of 25 ≧ G / F ≧ 0.5, the initial efficiency and the maintenance rate are further improved.

（実施例１２−１〜実施例１２−４）
負極中の炭素系活物質材の種類を変化させたことを除き、実施例１０−２と同様に、二次電池の製造を行った。 (Example 12-1 to Example 12-4)
A secondary battery was manufactured in the same manner as in Example 10-2 except that the type of the carbon-based active material in the negative electrode was changed.

実施例１２−１〜１２−４の二次電池のサイクル特性及び初回充放電特性を調べたところ、表１２に示した結果が得られた。   When the cycle characteristics and initial charge / discharge characteristics of the secondary batteries of Examples 12-1 to 12-4 were examined, the results shown in Table 12 were obtained.

Figure 0006448525
Figure 0006448525

表１２からわかるように、負極活物質層中の炭素系活物質粒子としては、人造黒鉛や天然黒鉛などの黒鉛系材料が含まれていることが望ましい。これは、黒鉛系炭素材の初回効率、維持率が高いため、ケイ素系活物質粒子と混合して負極を作製した際、電池特性が相対的に向上するためである。   As can be seen from Table 12, it is desirable that the carbon-based active material particles in the negative electrode active material layer include graphite-based materials such as artificial graphite and natural graphite. This is because the initial efficiency and maintenance rate of the graphite-based carbon material are high, and therefore, when the negative electrode is produced by mixing with the silicon-based active material particles, the battery characteristics are relatively improved.

（実施例１３−１）
以下の方法により、図３に示したようなラミネートフィルム型の二次電池を作製した。 (Example 13-1)
A laminate film type secondary battery as shown in FIG. 3 was produced by the following method.

最初に正極を作製した。正極活物質はリチウムニッケルコバルト複合酸化物であるＬｉＮｉ０．７Ｃｏ０．２５Ａｌ０．０５Ｏを９５質量％と、正極導電助剤２．５質量％と、正極結着剤（ポリフッ化ビニリデン：ＰＶＤＦ）２．５質量％とを混合し、正極合剤とした。続いて正極合剤を有機溶剤（Ｎ−メチル−２−ピロリドン：ＮＭＰ）に分散させてペースト状のスラリーとした。続いてダイヘッドを有するコーティング装置で正極集電体の両面にスラリーを塗布し、熱風式乾燥装置で乾燥した。この時正極集電体は厚み１５μｍのものを用いた。最後にロールプレスで圧縮成型を行った。 First, a positive electrode was produced. The positive electrode active material is 95% by mass of LiNi 0.7 Co 0.25 Al 0.05 O, which is a lithium nickel cobalt composite oxide, 2.5% by mass of a positive electrode conductive additive, and a positive electrode binder (polyvinylidene fluoride). : PVDF) 2.5% by mass was mixed to obtain a positive electrode mixture. Subsequently, the positive electrode mixture was dispersed in an organic solvent (N-methyl-2-pyrrolidone: NMP) to obtain a paste slurry. Subsequently, the slurry was applied to both surfaces of the positive electrode current collector with a coating apparatus having a die head, and dried with a hot air drying apparatus. At this time, a positive electrode current collector having a thickness of 15 μm was used. Finally, compression molding was performed with a roll press.

次に負極を作製した。まず、負極活物質を以下のようにして作製した。金属ケイ素と二酸化ケイ素を混合した原料を反応炉に導入し、１０Ｐａの真空度の雰囲気中で気化させたものを吸着板上に堆積させ、十分に冷却した後、堆積物を取出しボールミルで粉砕した。このようにして得たケイ素化合物粒子のＳｉＯｘのｘの値は１．０であった。続いて、ケイ素化合物粒子の粒径を分級により調整した。その後、熱分解ＣＶＤを行うことで、ケイ素化合物粒子の表面に炭素被膜を被覆した。このとき、熱分解ＣＶＤにはロータリーキルンタイプの反応炉を用い、炭素源としてメタンガス、炉内の温度を１０００℃、圧力を１ａｔｍ、ＣＶＤ時間を６時間とした。 Next, a negative electrode was produced. First, a negative electrode active material was produced as follows. A raw material mixed with metallic silicon and silicon dioxide was introduced into a reaction furnace, and vaporized in a 10 Pa vacuum atmosphere was deposited on an adsorption plate, cooled sufficiently, and then the deposit was taken out and pulverized with a ball mill. . The x value of SiO x of the silicon compound particles thus obtained was 1.0. Subsequently, the particle size of the silicon compound particles was adjusted by classification. Then, the carbon film was coat | covered on the surface of the silicon compound particle | grain by performing pyrolysis CVD. At this time, a rotary kiln type reactor was used for thermal decomposition CVD, methane gas as a carbon source, the temperature in the furnace was 1000 ° C., the pressure was 1 atm, and the CVD time was 6 hours.

続いて、ケイ素化合物粒子に酸化還元法によりリチウムを挿入し改質した。まず、ケイ素化合物粒子を、リチウム片と、直鎖ポリフェニレン化合物であるビフェニルとをテトラヒドロフラン（以下、ＴＨＦとも呼称する）に溶解させた溶液（溶液Ａ１）に浸漬した。溶液Ａ１は、ＴＨＦ溶媒にビフェニルを１ｍｏｌ／Ｌの濃度で溶解させた後に、このＴＨＦとビフェニルの混合液に対して１０質量％の質量分のリチウム片を加えることで作製した。また、ケイ素化合物粒子を浸漬する際の溶液の温度は２０℃で、浸漬時間は１０時間とした。その後、ケイ素化合物粒子を濾取した。以上の処理により、ケイ素化合物粒子にリチウムを挿入した。 Subsequently, lithium was inserted into the silicon compound particles and modified by a redox method. First, the silicon compound particles were immersed in a solution (solution A 1 ) in which lithium pieces and biphenyl, which is a linear polyphenylene compound, were dissolved in tetrahydrofuran (hereinafter also referred to as THF). The solution A 1 was prepared by adding after the biphenyl in THF solvent dissolved at a concentration of 1 mol / L, the lithium pieces 10 mass% of the mass fraction with respect to a mixed solution of the THF and biphenyl. The temperature of the solution when dipping the silicon compound particles was 20 ° C., and the dipping time was 10 hours. Thereafter, silicon compound particles were collected by filtration. Through the above treatment, lithium was inserted into the silicon compound particles.

次に、ＴＨＦにナフタレンを溶解させた溶液（溶液Ｂ）に、リチウム挿入後のケイ素化合物粒子を浸漬した。溶液Ｂは、ＴＨＦ溶媒にナフタレンを２ｍｏｌ／Ｌの濃度で溶解させて作製した。また、ケイ素化合物粒子を浸漬する際の溶液の温度は２０℃、浸漬時間は２０時間とした。その後、ケイ素化合物粒子を濾取した。   Next, the silicon compound particles after lithium insertion were immersed in a solution (solution B) in which naphthalene was dissolved in THF. Solution B was prepared by dissolving naphthalene in a THF solvent at a concentration of 2 mol / L. The temperature of the solution when dipping the silicon compound particles was 20 ° C., and the dipping time was 20 hours. Thereafter, silicon compound particles were collected by filtration.

次に、溶液Ｂに接触させた後のケイ素化合物粒子を、ＴＨＦにｐ−ベンゾキノンを１ｍｏｌ／Ｌの濃度で溶解させた溶液（溶液Ｃ）に浸漬した。浸漬時間は２時間とした。その後、ケイ素化合物粒子を濾取した。以上の処理により、ケイ素化合物粒子の内部に、Ｌｉ２ＳｉＯ３及びＬｉ４ＳｉＯ４を生成した。 Next, the silicon compound particles after being brought into contact with the solution B were immersed in a solution (solution C) in which p-benzoquinone was dissolved in THF at a concentration of 1 mol / L. The immersion time was 2 hours. Thereafter, silicon compound particles were collected by filtration. Through the above treatment, Li 2 SiO 3 and Li 4 SiO 4 were generated inside the silicon compound particles.

次に、ケイ素化合物粒子を洗浄処理し、洗浄処理後のケイ素化合物粒子を減圧下で乾燥処理した。このようにして、負極活物質粒子を得た。   Next, the silicon compound particles were washed, and the silicon compound particles after the washing treatment were dried under reduced pressure. In this way, negative electrode active material particles were obtained.

次に、実施例１−１と同様の方法で、単離した炭素被膜の多点ＢＥＴ法による比表面積及び１．０ｇ／ｃｍ３の密度に圧縮した時の圧縮抵抗率を測定した。 Next, the specific surface area by the multipoint BET method of the isolated carbon film and the compression resistivity when compressed to a density of 1.0 g / cm 3 were measured by the same method as in Example 1-1.

その結果、単離した炭素被膜の多点ＢＥＴ法による比表面積は１８０ｍ２／ｇ、１．０ｇ／ｃｍ３の密度に圧縮した時の圧縮抵抗率は８．０×１０−３Ω・ｃｍであった。 In result, the compression resistance when the specific surface area by a multipoint BET method of the isolated carbon film compressed to a density of 180m 2 /g,1.0g/cm 3 is 8.0 × 10 -3 Ω · cm there were.

次に、負極活物質粒子と、炭素系活物質を１：９の質量比で配合し、混合負極活物質を作製した。ここで、炭素系活物質としては、ピッチ層で被覆した天然黒鉛及び人造黒鉛を５：５の質量比で混合したものを使用した。また、炭素系活物質のメディアン径は２０μｍであった。   Next, the negative electrode active material particles and the carbon-based active material were blended at a mass ratio of 1: 9 to prepare a mixed negative electrode active material. Here, as the carbon-based active material, a mixture of natural graphite and artificial graphite coated with a pitch layer at a mass ratio of 5: 5 was used. The median diameter of the carbon-based active material was 20 μm.

次に、作製した混合負極活物質、導電助剤１（カーボンナノチューブ、ＣＮＴ）、導電助剤２（メディアン径が約５０ｎｍの炭素微粒子）、スチレンブタジエンゴム（スチレンブタジエンコポリマー、以下、ＳＢＲと称する）、カルボキシメチルセルロース（以下、ＣＭＣと称する）９２．５：１：１：２．５：３の乾燥質量比で混合した後、純水で希釈し負極合剤スラリーとした。尚、上記のＳＢＲ、ＣＭＣは負極バインダー（負極結着剤）である。   Next, the prepared mixed negative electrode active material, conductive additive 1 (carbon nanotube, CNT), conductive additive 2 (carbon fine particles having a median diameter of about 50 nm), styrene butadiene rubber (styrene butadiene copolymer, hereinafter referred to as SBR) And carboxymethylcellulose (hereinafter referred to as CMC) 92.5: 1: 1: 2.5: 3, and then mixed with a dry mass ratio, and diluted with pure water to obtain a negative electrode mixture slurry. In addition, said SBR and CMC are negative electrode binders (negative electrode binder).

また、負極集電体としては、厚さ１５μｍの電解銅箔を用いた。この電解銅箔には、炭素及び硫黄がそれぞれ７０質量ｐｐｍの濃度で含まれていた。最後に、負極合剤スラリーを負極集電体に塗布し真空雰囲気中で１００℃×１時間の乾燥を行った。乾燥後の、負極の片面における単位面積あたりの負極活物質層の堆積量（面積密度とも称する）は５ｍｇ／ｃｍ２であった。 As the negative electrode current collector, an electrolytic copper foil having a thickness of 15 μm was used. This electrolytic copper foil contained carbon and sulfur at a concentration of 70 mass ppm. Finally, the negative electrode mixture slurry was applied to the negative electrode current collector and dried in a vacuum atmosphere at 100 ° C. for 1 hour. The amount of deposition (also referred to as area density) of the negative electrode active material layer per unit area on one side of the negative electrode after drying was 5 mg / cm 2 .

次に、溶媒（４−フルオロ−１，３−ジオキソラン−２−オン（ＦＥＣ）、エチレンカーボネート（ＥＣ）およびジメチルカーボネート（ＤＭＣ））を混合した後、電解質塩（六フッ化リン酸リチウム：ＬｉＰＦ６）を溶解させて電解液を調製した。この場合には、溶媒の組成を体積比でＦＥＣ：ＥＣ：ＤＭＣ＝１０：２０：７０とし、電解質塩の含有量を溶媒に対して１．２ｍｏｌ／ｋｇとした。 Next, after mixing a solvent (4-fluoro-1,3-dioxolan-2-one (FEC), ethylene carbonate (EC) and dimethyl carbonate (DMC)), an electrolyte salt (lithium hexafluorophosphate: LiPF) 6 ) was dissolved to prepare an electrolytic solution. In this case, the composition of the solvent was FEC: EC: DMC = 10: 20: 70 by volume ratio, and the content of the electrolyte salt was 1.2 mol / kg with respect to the solvent.

次に、以下のようにして二次電池を組み立てた。最初に、正極集電体の一端にアルミリードを超音波溶接し、負極集電体の一端にはニッケルリードを溶接した。続いて、正極、セパレータ、負極、セパレータをこの順に積層し、長手方向に倦回させ倦回電極体を得た。その捲き終わり部分をＰＥＴ保護テープで固定した。セパレータは多孔性ポリプロピレンを主成分とするフィルムにより多孔性ポリエチレンを主成分とするフィルムに挟まれた積層フィルム（厚さ１２μｍ）を用いた。続いて、外装部材間に電極体を挟んだ後、一辺を除く外周縁部同士を熱融着し、内部に電極体を収納した。外装部材はナイロンフィルム、アルミ箔及び、ポリプロピレンフィルムが積層されたアルミラミネートフィルムを用いた。続いて、開口部から調整した電解液を注入し、真空雰囲気下で含浸した後、熱融着し、封止した。   Next, a secondary battery was assembled as follows. First, an aluminum lead was ultrasonically welded to one end of the positive electrode current collector, and a nickel lead was welded to one end of the negative electrode current collector. Subsequently, a positive electrode, a separator, a negative electrode, and a separator were laminated in this order, and wound in the longitudinal direction to obtain a wound electrode body. The end portion was fixed with PET protective tape. As the separator, a laminated film (thickness: 12 μm) sandwiched between a film mainly composed of porous polyethylene and a film mainly composed of porous polypropylene was used. Subsequently, after sandwiching the electrode body between the exterior members, the outer peripheral edges excluding one side were heat-sealed, and the electrode body was housed inside. As the exterior member, a nylon film, an aluminum foil, and an aluminum laminate film in which a polypropylene film was laminated were used. Subsequently, an electrolytic solution prepared from the opening was injected, impregnated in a vacuum atmosphere, heat-sealed, and sealed.

以上のようにして作製した二次電池のサイクル特性及び初回充放電特性を、実施例１−１と同様の方法で評価した。   The cycle characteristics and initial charge / discharge characteristics of the secondary battery produced as described above were evaluated by the same method as in Example 1-1.

（実施例１３−２〜実施例１３−５）
単離した炭素被膜の吸脱着等温線のＩＵＰＡＣ分類、単離した炭素被膜の圧縮密度（５０ＭＰａ加圧時）を表１３のように変化させたこと以外、実施例１３−１と同様に二次電池の製造を行い、サイクル特性及び初回充放電特性を評価した。単離した炭素被膜の吸脱着等温線のＩＵＰＡＣ分類、単離した炭素被膜の圧縮密度（５０ＭＰａ加圧時）の変化はＣＶＤ温度、時間およびＣＶＤ時のケイ素化合物粒子の撹拌度を調節することで制御可能である。 (Example 13-2 to Example 13-5)
Secondary as in Example 13-1, except that the IUPAC classification of the adsorption / desorption isotherm of the isolated carbon coating and the compression density (at 50 MPa pressurization) of the isolated carbon coating were changed as shown in Table 13. The battery was manufactured, and cycle characteristics and initial charge / discharge characteristics were evaluated. The IUPAC classification of the adsorption and desorption isotherm of the isolated carbon film, the change in the compression density (at 50 MPa pressurization) of the isolated carbon film can be changed by adjusting the CVD temperature, time, and the degree of stirring of the silicon compound particles during the CVD. It can be controlled.

（比較例１３−１〜比較例１３−４）
単離した炭素被膜の比表面積、単離した炭素被膜の１．０ｇ／ｃｍ３の密度に圧縮した時の圧縮抵抗率、ケイ素化合物表面における炭素被膜の平均真密度、単離した炭素被膜の吸脱着等温線のＩＵＰＡＣ分類を表１３のように変化させたこと以外、実施例１３−１と同様に二次電池の製造を行い、サイクル特性及び初回充放電特性を評価した。これらのパラメーターも、ＣＶＤ温度、時間およびＣＶＤ時のケイ素化合物粒子の撹拌度を調節することで制御可能である。 (Comparative Example 13-1 to Comparative Example 13-4)
Specific surface area of isolated carbon film, compression resistivity when compressed to a density of 1.0 g / cm 3 of isolated carbon film, average true density of carbon film on silicon compound surface, absorption of isolated carbon film A secondary battery was manufactured in the same manner as in Example 13-1, except that the IUPAC classification of the desorption isotherm was changed as shown in Table 13, and cycle characteristics and initial charge / discharge characteristics were evaluated. These parameters can also be controlled by adjusting the CVD temperature, time, and the degree of stirring of the silicon compound particles during CVD.

このとき、実施例１３−１〜１３−５及び比較例１３−１〜１３−４の負極活物質粒子は以下のような性質を有していた。負極活物質粒子のメディアン径は４μｍであった。また、ケイ素化合物は、Ｘ線回折により得られるＳｉ（１１１）結晶面に起因する回折ピークの半値幅（２θ）が２．２５７°であり、そのＳｉ（１１１）結晶面に起因する結晶子サイズは３．７７ｎｍであった。   At this time, the negative electrode active material particles of Examples 13-1 to 13-5 and Comparative Examples 13-1 to 13-4 had the following properties. The median diameter of the negative electrode active material particles was 4 μm. Further, the silicon compound has a half-value width (2θ) of a diffraction peak due to the Si (111) crystal plane obtained by X-ray diffraction of 2.257 °, and a crystallite size due to the Si (111) crystal plane. Was 3.77 nm.

負極活物質粒子において、２９Ｓｉ−ＭＡＳ−ＮＭＲ スペクトルから得られる、ケミカルシフト値として−７５〜−９４ｐｐｍで与えられる結晶性シリコン領域及びＬｉシリケート領域の最大ピーク強度値Ｈと、ケミカルシフト値として−９５〜−１５０ｐｐｍで与えられるシリカ領域のピーク強度値Ｉとの関係がＨ＞Ｉであった。 In the negative electrode active material particles, the maximum peak intensity value H of the crystalline silicon region and the Li silicate region given by the chemical shift value of −75 to −94 ppm obtained from the 29 Si-MAS-NMR spectrum, and the chemical shift value of − The relationship with the peak intensity value I in the silica region given at 95 to -150 ppm was H> I.

また、上記のように作製した負極と対極リチウムとから、２０３２サイズのコイン電池型の試験セルを作製し、その放電挙動を評価した。より具体的には、まず、対極Ｌｉで０Ｖまで定電流定電圧充電を行い、電流密度が０．０５ｍＡ／ｃｍ２に達した時点で充電を終止させた。その後、１．２Ｖまで定電流放電を行った。この時の電流密度は０．２ｍＡ／ｃｍ２であった。この充放電を３０回繰り返し、各充放電において得られたデータから、縦軸を容量の変化率（ｄＱ／ｄＶ）、横軸を電圧（Ｖ）としてグラフを描き、Ｖが０．４〜０．５５（Ｖ）の範囲にピークが得られるかを確認した。その結果、実施例、比較例では、３０回以内の充放電において上記ピークは得られ、上記ピークが初めて発現した充放電から３０回目の充放電まで、全ての充放電において上記ピークが得られた。 Further, a 2032 size coin cell type test cell was prepared from the negative electrode and the counter electrode lithium prepared as described above, and the discharge behavior was evaluated. More specifically, first, constant current and constant voltage charging was performed up to 0 V with the counter electrode Li, and the charging was terminated when the current density reached 0.05 mA / cm 2 . Then, constant current discharge was performed to 1.2V. The current density at this time was 0.2 mA / cm 2 . This charge / discharge was repeated 30 times, and from the data obtained in each charge / discharge, a graph was drawn with the vertical axis representing the rate of change in capacity (dQ / dV) and the horizontal axis representing the voltage (V), where V was 0.4-0. It was confirmed whether a peak was obtained in the range of .55 (V). As a result, in Examples and Comparative Examples, the peak was obtained in charge and discharge within 30 times, and the peak was obtained in all charge and discharge from the charge and discharge in which the peak first appeared until the 30th charge and discharge. .

実施例１３−１〜１３−５、比較例１３−１〜１３−４の評価結果を表１３に示す。   Table 13 shows the evaluation results of Examples 13-1 to 13-5 and Comparative Examples 13-1 to 13-4.

Figure 0006448525
Figure 0006448525

表１３から分かるように、単離した炭素被膜の比表面積が、５ｍ２／ｇ以上１０００ｍ２／ｇ以下である実施例１３−１〜実施例１３−５では、比表面積がこの範囲外である比較例１３−３、比較例１３−４よりも良好な電池特性が得られる。また、炭素被膜の密度が１．０ｇ／ｃｍ３の時の圧縮抵抗率が１．０×１０−３Ω・ｃｍ以上１．０Ω・ｃｍ以下である実施例１３−１〜実施例１３−５では、圧縮抵抗率がこの範囲外である比較例１３−３、比較例１３−４よりも良好な電池特性が得られる。 As can be seen from Table 13, in Examples 13-1 to 13-5 where the specific surface area of the isolated carbon coating is 5 m 2 / g or more and 1000 m 2 / g or less, the specific surface area is outside this range. Battery characteristics better than those of Comparative Example 13-3 and Comparative Example 13-4 are obtained. In addition, Example 13-1 to Example 13-5 in which the compressive resistivity when the density of the carbon film is 1.0 g / cm 3 is 1.0 × 10 −3 Ω · cm or more and 1.0 Ω · cm or less. Thus, better battery characteristics can be obtained than Comparative Examples 13-3 and 13-4 whose compression resistivity is outside this range.

（実施例１４−１）
負極活物質粒子を結晶性シリコン領域及びＬｉシリケート領域の最大ピーク強度値Ｈとシリケート領域に由来するピーク強度値Ｉとの関係がＨ＜Ｉのものとしたこと以外、実施例１３−１と同じ条件で二次電池を作製し、サイクル特性及び初回効率を評価した。この場合、改質時にリチウムの挿入量を減らすことで、Ｌｉ２ＳｉＯ３の量を減らし、Ｌｉ２ＳｉＯ３に由来するピークの強度Ｈを小さくした。 (Example 14-1)
Same as Example 13-1, except that the relationship between the maximum peak intensity value H of the crystalline silicon region and the Li silicate region and the peak intensity value I derived from the silicate region of the negative electrode active material particles was H <I Secondary batteries were manufactured under the conditions, and cycle characteristics and initial efficiency were evaluated. In this case, by reducing the amount of insertion of lithium during reforming to reduce the amount of Li 2 SiO 3, it has a small intensity H of a peak derived from the Li 2 SiO 3.

Figure 0006448525
Figure 0006448525

表１４から分かるように、ピーク強度の関係がＨ＞Ｉである場合の方が、電池特性が向上した。   As can be seen from Table 14, the battery characteristics improved when the peak intensity relationship was H> I.

（実施例１５−１）
上記試験セルにおける３０回の充放電で得られたＶ−ｄＱ／ｄＶ曲線において、いずれの充放電でもＶが０．４０Ｖ〜０．５５Ｖの範囲にピークが得られなかった負極活物質を用いた以外、実施例１３−１と同じ条件で二次電池を作製し、サイクル特性及び初回効率を評価した。 (Example 15-1)
In the V-dQ / dV curve obtained by charging and discharging 30 times in the test cell, a negative electrode active material in which no peak was obtained in the range of 0.40 V to 0.55 V in any charging / discharging was used. A secondary battery was fabricated under the same conditions as in Example 13-1, and the cycle characteristics and initial efficiency were evaluated.

Figure 0006448525
Figure 0006448525

放電カーブ形状がより鋭く立ち上がるためには、ケイ素化合物（ＳｉＯｘ）において、ケイ素（Ｓｉ）と同様の放電挙動を示す必要がある。３０回の充放電で上記の範囲にピークが発現しない、ケイ素化合物は比較的緩やかな放電カーブとなるため、二次電池にした際に、若干初期効率が低下する結果となった。ピークが３０回以内の充放電で発現するものであれば、安定したバルクが形成され、容量維持率及び初期効率が向上した。   In order for the discharge curve shape to rise more sharply, the silicon compound (SiOx) needs to exhibit a discharge behavior similar to that of silicon (Si). Since the silicon compound that does not exhibit a peak in the above-described range after 30 charge / discharge cycles has a relatively gentle discharge curve, the initial efficiency is slightly lowered when a secondary battery is obtained. If the peak appears within 30 charge / discharge cycles, a stable bulk was formed, and the capacity retention rate and initial efficiency were improved.

（実施例１６−１）
負極集電体として、炭素及び硫黄を含まない銅箔を用いたこと以外、実施例１３−１と同じ条件で二次電池を作製し、サイクル特性及び初回効率を評価した。 (Example 16-1)
A secondary battery was produced under the same conditions as in Example 13-1, except that a copper foil containing no carbon and sulfur was used as the negative electrode current collector, and the cycle characteristics and initial efficiency were evaluated.

Figure 0006448525
Figure 0006448525

負極の集電体に炭素及び硫黄をそれぞれ１００質量ｐｐｍ以下含む場合、集電体の強度が向上する。従って、二次電池の充放電時における膨張、収縮が大きいケイ素系負極活物質を用いる場合、これに伴う集電体の変形及び歪みを抑制でき、実施例１３−１のように電池特性、特にサイクル特性が向上する。   When the current collector of the negative electrode contains 100 ppm by mass or less of carbon and sulfur, the strength of the current collector is improved. Therefore, when using a silicon-based negative electrode active material having a large expansion and contraction during charge / discharge of the secondary battery, it is possible to suppress the deformation and distortion of the current collector, and the battery characteristics, particularly as in Example 13-1. Cycle characteristics are improved.

（比較例１７−１）
ケイ素化合物粒子へのリチウムの挿入を行わなかったこと以外、実施例１３−１と同様に二次電池の製造を行い、サイクル特性及び初回充放電特性を評価した。 (Comparative Example 17-1)
A secondary battery was produced in the same manner as in Example 13-1, except that lithium was not inserted into the silicon compound particles, and cycle characteristics and initial charge / discharge characteristics were evaluated.

Figure 0006448525
Figure 0006448525

表１７から分かるように、ケイ素活物質粒子にリチウムを挿入することで改質を行った実施例１３−１は、改質を行わなかった実施例１７−１よりも初期効率、維持率がともに向上した。   As can be seen from Table 17, Example 13-1, which was modified by inserting lithium into the silicon active material particles, had both initial efficiency and maintenance rate higher than those of Example 17-1, which was not modified. Improved.

なお、本発明は、上記実施形態に限定されるものではない。上記実施形態は例示であり、本発明の特許請求の範囲に記載された技術的思想と実質的に同一な構成を有し、同様な作用効果を奏するものは、いかなるものであっても本発明の技術的範囲に包含される。   The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

１０…負極、 １１…負極集電体、 １２…負極活物質層、
２０…リチウム二次電池（ラミネートフィルム型）、 ２１…電極体、
２２…正極リード（正極アルミリード）、
２３…負極リード（負極ニッケルリード）、 ２４…密着フィルム、
２５…外装部材。 10 ... negative electrode, 11 ... negative electrode current collector, 12 ... negative electrode active material layer,
20 ... lithium secondary battery (laminated film type), 21 ... electrode body,
22 ... Positive electrode lead (positive electrode aluminum lead),
23 ... negative electrode lead (negative electrode nickel lead), 24 ... adhesion film,
25. Exterior member.

Claims (25)

負極活物質粒子を有し、該負極活物質粒子はケイ素化合物（ＳｉＯｘ：０．５≦ｘ≦１．６）を含有するものである非水電解質二次電池用負極活物質であって、
前記負極活物質粒子は表面の少なくとも一部に炭素被膜を有し、
該炭素被膜は、前記炭素被膜を前記負極活物質粒子から単離して測定した多点ＢＥＴ法による比表面積が５ｍ２／ｇ以上１０００ｍ２／ｇ以下であり、かつ、
前記炭素被膜は、前記炭素被膜を前記負極活物質粒子から単離して測定した圧縮抵抗率が、１．０ｇ／ｃｍ３の密度に圧縮した時に１．０×１０−３Ω・ｃｍ以上１．０Ω・ｃｍ以下であり、
前記炭素被膜の真密度が１．２ｇ／ｃｍ ３ 以上１．９ｇ／ｃｍ ３ 以下の範囲であることを特徴とする非水電解質二次電池用負極活物質。 A negative electrode active material for a non-aqueous electrolyte secondary battery having negative electrode active material particles, the negative electrode active material particles containing a silicon compound (SiO x : 0.5 ≦ x ≦ 1.6),
The negative electrode active material particles have a carbon coating on at least a part of the surface,
The carbon coating has a specific surface area of 5 m 2 / g or more and 1000 m 2 / g or less by a multi-point BET method measured by isolating the carbon coating from the negative electrode active material particles, and
The carbon film has a compression resistivity of 1.0 × 10 −3 Ω · cm or more when the carbon film is compressed to a density of 1.0 g / cm 3 when the carbon film is isolated from the negative electrode active material particles. 0Ω · cm Ri der below,
True density of 1.2 g / cm 3 or more 1.9 g / cm 3 negative active material for a nonaqueous electrolyte secondary battery characterized by the following ranges der Rukoto of the carbon film. 前記炭素被膜は、前記炭素被膜を前記負極活物質粒子から単離し、該単離した炭素被膜を単位面積あたりの質量が０．１５ｇ／ｃｍ２となるように測定容器に仕込んだ後に、５０ＭＰａで加圧して圧縮した場合の圧縮密度が１．０ｇ／ｃｍ３以上１．８ｇ／ｃｍ３以下であることを特徴とする請求項１に記載の非水電解質二次電池用負極活物質。 The carbon coating is prepared by isolating the carbon coating from the negative electrode active material particles, and charging the isolated carbon coating into a measurement container so that the mass per unit area is 0.15 g / cm 2. 2. The negative electrode active material for a nonaqueous electrolyte secondary battery according to claim 1, wherein a compression density when compressed by pressing is 1.0 g / cm 3 or more and 1.8 g / cm 3 or less. 前記炭素被膜の含有率が、前記負極活物質粒子に対し０．１質量％以上２５質量％以下であることを特徴とする請求項１又は請求項２に記載の非水電解質二次電池用負極活物質。 The content of the carbon coating, the negative active for a non-aqueous electrolyte secondary battery negative electrode according to claim 1 or claim 2 with respect to material particles, characterized in that 25 wt% or less than 0.1 wt% Active material. 前記炭素被膜が、前記炭素被膜を前記負極活物質粒子から単離して測定した窒素ガスによる吸脱着等温線において、前記吸脱着等温線のＩＵＰＡＣ分類におけるＩＩ型又はＩＩＩ型の特徴を有することを特徴とする請求項１から請求項３のいずれか１項に記載の非水電解質二次電池用負極活物質。 The carbon coating has a characteristic of type II or type III in the IUPAC classification of the adsorption / desorption isotherm in an adsorption / desorption isotherm by nitrogen gas measured by isolating the carbon coating from the negative electrode active material particles. The negative electrode active material for a nonaqueous electrolyte secondary battery according to any one of claims 1 to 3 . 前記炭素被膜の単離を、前記負極活物質粒子をフッ化水素酸及び硝酸を含む溶液と反応させることより、前記負極活物質粒子から前記ケイ素化合物を除去することで行うことを特徴とする請求項１から請求項４のいずれか１項に記載の非水電解質二次電池用負極活物質。 The carbon coating is isolated by reacting the negative electrode active material particles with a solution containing hydrofluoric acid and nitric acid to remove the silicon compound from the negative electrode active material particles. The negative electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 4 . 前記炭素被膜が、ラマンスペクトル分析により得られたラマンスペクトルにおいて、１３３０ｃｍ−１と１５８０ｃｍ−１に散乱ピークを有し、それらの散乱ピークの強度の比Ｉ１３３０／Ｉ１５８０が０．７＜Ｉ１３３０／Ｉ１５８０＜２．０を満たすことを特徴とする請求項１から請求項５のいずれか１項に記載の非水電解質二次電池用負極活物質。 Wherein the carbon coating is in the Raman spectrum obtained by Raman spectrum analysis, it has a scattering peak at 1330 cm -1 and 1580 cm -1, a ratio of the intensity of their scattering peak I 1330 / I 1580 is 0.7 <I 1330 / I 1580 negative active material for a nonaqueous electrolyte secondary battery as claimed in any one of claims 5, characterized in that satisfy <2.0. 前記炭素被膜が、ＴＯＦ−ＳＩＭＳによって、ＣｙＨｚ系化合物のフラグメントが検出され、該ＣｙＨｚ系化合物のフラグメントとして、６≧ｙ≧２、２ｙ＋２≧ｚ≧２ｙ−２の範囲を満たすものが少なくとも一部に検出されることを特徴とする請求項１から請求項６のいずれか１項に記載の非水電解質二次電池用負極活物質。 In the carbon coating, a fragment of the C y H z compound is detected by TOF-SIMS, and the fragment of the C y H z compound satisfies the range of 6 ≧ y ≧ 2, 2y + 2 ≧ z ≧ 2y−2. 7. The negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein the substance is detected at least in part. 前記炭素被膜で検出されるＣｙＨｚ系化合物のフラグメントが、ＴＯＦ−ＳＩＭＳにおけるＣ４Ｈ９の検出強度ＤとＣ３Ｈ５の検出強度Ｅが２．５≧Ｄ／Ｅ≧０．３の関係を満たすものであることを特徴とする請求項７に記載の非水電解質二次電池用負極活物質。 The fragment of the C y H z compound detected by the carbon film has a detection intensity D of C 4 H 9 and a detection intensity E of C 3 H 5 of 2.5 ≧ D / E ≧ 0.3 in TOF-SIMS. The negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 7 , wherein the negative electrode active material satisfies the following relationship. 前記炭素被膜の平均厚さが５ｎｍ以上５０００ｎｍ以下のものであることを特徴とする請求項１から請求項８のいずれか１項に記載の非水電解質二次電池用負極活物質。 Negative active material for a non-aqueous electrolyte secondary battery as claimed in any one of claims 8, wherein the average thickness of the carbon coating is of 5nm or 5000nm or less. 前記炭素被膜の平均被覆率が３０％以上のものであることを特徴とする請求項１から請求項９のいずれか１項に記載の非水電解質二次電池用負極活物質。 Negative active material for a non-aqueous electrolyte secondary battery as claimed in any one of claims 9, wherein the average coverage of the carbon film is not less than 30%. 前記炭素被膜が、炭素を含む化合物を熱分解することで得られたものであることを特徴とする請求項１から請求項１０のいずれか１項に記載の非水電解質二次電池用負極活物質。 Wherein the carbon coating is either negative active for a non-aqueous electrolyte secondary battery according to one of claims 10 to compounds containing carbon from claim 1, characterized in that is obtained by thermal decomposition material. 前記ケイ素化合物において、２９Ｓｉ−ＭＡＳ−ＮＭＲスペクトルから得られるケミカルシフト値として、−２０〜−７４ｐｐｍで与えられるアモルファスシリコン領域のピーク面積Ａと−７５〜−９４ｐｐｍで与えられる結晶性シリコン領域及びＬｉシリケート領域のピーク面積Ｂと−９５〜−１５０ｐｐｍに与えられるシリカ領域のピーク面積Ｃが式（１）を満たすことを特徴とする請求項１から請求項１１のいずれか１項に記載の非水電解質二次電池用負極活物質。
式（１）：５．０≧Ａ／Ｂ≧０．０１、６．０≧（Ａ＋Ｂ）／Ｃ≧０．０２ In the silicon compound, as the chemical shift value obtained from the 29 Si-MAS-NMR spectrum, the peak area A of the amorphous silicon region given by −20 to −74 ppm and the crystalline silicon region given by −75 to −94 ppm and Li The non-water according to any one of claims 1 to 11 , wherein the peak area B of the silicate region and the peak area C of the silica region given to -95 to -150 ppm satisfy the formula (1). Negative electrode active material for electrolyte secondary battery.
Formula (1): 5.0 ≧ A / B ≧ 0.01, 6.0 ≧ (A + B) /C≧0.02 前記負極活物質粒子は、Ｘ線回折により得られるＳｉ（１１１）結晶面に起因する回折ピークの半値幅（２θ）が１．２°以上であると共に、その結晶面に起因する結晶子サイズが７．５ｎｍ以下であることを特徴とする請求項１から請求項１２のいずれか１項に記載の非水電解質二次電池用負極活物質。 The negative electrode active material particles have a full width at half maximum (2θ) of a diffraction peak attributed to the Si (111) crystal plane obtained by X-ray diffraction of 1.2 ° or more and a crystallite size attributed to the crystal plane. negative active material for a non-aqueous electrolyte secondary battery as claimed in any one of claims 12, wherein the 7.5nm or less. 前記負極活物質粒子のメディアン径が０．５μｍ以上２０μｍ以下であることを特徴とする請求項１から請求項１３のいずれか１項に記載の非水電解質二次電池用負極活物質。 The negative active material for a nonaqueous electrolyte secondary battery as claimed in any one of claims 13, wherein the median diameter of the negative electrode active material particles is 0.5μm or more 20μm or less. 前記負極活物質粒子の少なくとも一部にＬｉを含有することを特徴とする請求項１から請求項１４のいずれか１項に記載の非水電解質二次電池用負極活物質。 The negative electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 14 , wherein Li is contained in at least a part of the negative electrode active material particles. 前記負極活物質粒子の少なくとも一部に、Ｌｉ２ＳｉＯ３及びＬｉ４ＳｉＯ４のうち少なくとも１種以上を含有することを特徴とする請求項１５に記載の非水電解質二次電池用負極活物質。 The negative electrode active material for a nonaqueous electrolyte secondary battery according to claim 15 , wherein at least a part of Li 2 SiO 3 and Li 4 SiO 4 is contained in at least a part of the negative electrode active material particles. . 前記負極活物質粒子において、２９Ｓｉ−ＭＡＳ−ＮＭＲ スペクトルから得られる、ケミカルシフト値として−７５〜−９４ｐｐｍで与えられる結晶性シリコン領域及びＬｉシリケート領域の最大ピーク強度値Ｈと、ケミカルシフト値として−９５〜−１５０ｐｐｍで与えられるシリカ領域のピーク強度値Ｉが、Ｈ＞Ｉという関係を満たすものであることを特徴とする請求項１から請求項１６に記載の非水電解質二次電池用負極活物質。 In the negative electrode active material particles, the maximum peak intensity value H of the crystalline silicon region and Li silicate region given by -75 to -94 ppm as the chemical shift value obtained from the 29 Si-MAS-NMR spectrum, and the chemical shift value -95-150 ppm peak intensity value I is given silica region is, H> non-aqueous electrolyte secondary battery negative electrode according to claim 16 claims 1 to be characterized satisfies the relationship of I Active material. 前記非水電解質二次電池用負極活物質と炭素系活物質との混合物を含む負極電極と対極リチウムとから成る試験セルを作製し、該試験セルにおいて、前記非水電解質二次電池用負極活物質にリチウムを挿入するよう電流を流す充電と、前記非水電解質二次電池用負極活物質からリチウムを脱離するよう電流を流す放電とから成る充放電を３０回実施し、各充放電における放電容量Ｑを前記対極リチウムを基準とする前記負極電極の電位Ｖで微分した微分値ｄＱ／ｄＶと前記電位Ｖとの関係を示すグラフを描いた場合に、Ｘ回目以降（１≦Ｘ≦３０）の放電時における、前記負極電極の電位Ｖが０．４０Ｖ〜０．５５Ｖの範囲にピークを有するものであることを特徴とする請求項１から請求項１７のいずれか１項に記載の非水電解質二次電池用負極活物質。 A test cell comprising a negative electrode containing a mixture of the negative electrode active material for a nonaqueous electrolyte secondary battery and a carbon-based active material and counter lithium is prepared, and in the test cell, the negative electrode active for the nonaqueous electrolyte secondary battery is prepared. Charging / discharging consisting of charging for flowing current to insert lithium into the substance and discharging for flowing current to desorb lithium from the negative electrode active material for non-aqueous electrolyte secondary battery was performed 30 times. When a graph showing the relationship between the differential value dQ / dV obtained by differentiating the discharge capacity Q with respect to the potential V of the negative electrode with respect to the counter electrode lithium and the potential V is drawn, the Xth and subsequent times (1 ≦ X ≦ 30 The non-reactive electrode according to any one of claims 1 to 17 , wherein the potential V of the negative electrode has a peak in the range of 0.40V to 0.55V during the discharge of (1). For water electrolyte secondary battery Electrode active material. さらに、炭素系活物質粒子を含有することを特徴とする請求項１から請求項１８のいずれか１項に記載の非水電解質二次電池用負極活物質。 The negative electrode active material for a nonaqueous electrolyte secondary battery according to any one of claims 1 to 18 , further comprising carbon-based active material particles. 前記負極活物質粒子と前記炭素系活物質粒子の合計の質量に対する、前記負極活物質粒子の質量の割合が５質量％以上であることを特徴とする請求項１９に記載の非水電解質二次電池用負極活物質。 The nonaqueous electrolyte secondary according to claim 19 , wherein a ratio of the mass of the negative electrode active material particles to the total mass of the negative electrode active material particles and the carbon-based active material particles is 5% by mass or more. Negative electrode active material for batteries. 前記負極活物質粒子の平均粒径Ｆが、前記炭素系活物質粒子の平均粒径Ｇに対し、２５≧Ｇ／Ｆ≧０．５の関係を満たすことを特徴とする請求項１９又は請求項２０に記載の非水電解質二次電池用負極活物質。 The average particle diameter F of the negative electrode active material particles, to an average particle diameter G of the carbonaceous active material particles, according to claim 19 or claim characterized by satisfying the relationship of 25 ≧ G / F ≧ 0.5 20. A negative electrode active material for a nonaqueous electrolyte secondary battery according to 20 . 前記炭素系活物質粒子は黒鉛材料であることを特徴とする請求項１９から請求項２１のいずれか１項に記載の非水電解質二次電池用負極活物質。 The negative electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 19 to 21 , wherein the carbon-based active material particles are a graphite material. 請求項１から請求項２２のいずれか１項に記載の非水電解質二次電池用負極活物質を含む負極活物質層と、
負極集電体とを有し、
前記負極活物質層は前記負極集電体上に形成されており、
前記負極集電体は炭素及び硫黄を含むとともに、それらの含有量がいずれも１００質量ｐｐｍ以下であることを特徴とする非水電解質二次電池用負極。 A negative electrode active material layer containing the negative electrode active material for a nonaqueous electrolyte secondary battery according to any one of claims 1 to 22 ,
A negative electrode current collector,
The negative electrode active material layer is formed on the negative electrode current collector,
The negative electrode current collector includes carbon and sulfur, and the content thereof is 100 ppm by mass or less, and the negative electrode for a non-aqueous electrolyte secondary battery. 請求項１から請求項２２のいずれか１項に記載の非水電解質二次電池用負極活物質を含むことを特徴とする非水電解質二次電池。 23. A nonaqueous electrolyte secondary battery comprising the negative electrode active material for a nonaqueous electrolyte secondary battery according to any one of claims 1 to 22 . 負極活物質粒子を含む非水電解質二次電池用負極材の製造方法であって、
ＳｉＯｘ（０．５≦ｘ≦１．６）で表されるケイ素化合物の粒子を作製する工程と、
前記ケイ素化合物の粒子の表面の少なくとも一部を炭素被膜で被覆する工程と、
前記炭素被膜が被覆されたケイ素化合物の粒子から、前記炭素被膜を単離して測定した多点ＢＥＴ法による比表面積が５ｍ２／ｇ以上１０００ｍ２／ｇ以下であり、かつ、
前記炭素被膜が被覆されたケイ素化合物の粒子から、前記炭素被膜を単離して測定した圧縮抵抗率が、１．０ｇ／ｃｍ３の密度に圧縮した時に１．０×１０−３Ω・ｃｍ以上１．０Ω・ｃｍ以下であり、
前記炭素被膜の真密度が１．２ｇ／ｃｍ ３ 以上１．９ｇ／ｃｍ ３ 以下の範囲である前記炭素被膜が被覆されたケイ素化合物の粒子を選別する工程を有し、
該選別した前記炭素被膜が被覆されたケイ素化合物の粒子を負極活物質粒子として、非水電解質二次電池用負極材を製造することを特徴とする非水電解質二次電池用負極材の製造方法。
A method for producing a negative electrode material for a non-aqueous electrolyte secondary battery comprising negative electrode active material particles,
Producing a silicon compound particle represented by SiO x (0.5 ≦ x ≦ 1.6);
Coating at least a part of the surface of the silicon compound particles with a carbon coating;
The specific surface area by the multipoint BET method measured by isolating the carbon coating from the silicon compound particles coated with the carbon coating is 5 m 2 / g or more and 1000 m 2 / g or less, and
The compression resistivity measured by isolating the carbon coating from the silicon compound particles coated with the carbon coating is 1.0 × 10 −3 Ω · cm or more when compressed to a density of 1.0 g / cm 3. 1.0Ω · cm Ri der below,
And a step of selecting particles true density of 1.2 g / cm 3 or more 1.9 g / cm 3 or less range der of Ru said silicon compound carbon film is coated in the carbon film,
A method for producing a negative electrode material for a non-aqueous electrolyte secondary battery, comprising producing a negative electrode material for a non-aqueous electrolyte secondary battery using the selected silicon compound particles coated with the carbon coating as negative electrode active material particles. .
JP2015229550A 2015-02-26 2015-11-25 Non-aqueous electrolyte secondary battery negative electrode active material, non-aqueous electrolyte secondary battery negative electrode, non-aqueous electrolyte secondary battery, and method for producing non-aqueous electrolyte secondary battery negative electrode material Active JP6448525B2 (en)

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