JP5993337B2 - Negative electrode material for lithium ion secondary battery, method for producing the same, negative electrode for lithium ion secondary battery using the same, and lithium ion secondary battery - Google Patents

Negative electrode material for lithium ion secondary battery, method for producing the same, negative electrode for lithium ion secondary battery using the same, and lithium ion secondary battery Download PDF

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JP5993337B2
JP5993337B2 JP2013097040A JP2013097040A JP5993337B2 JP 5993337 B2 JP5993337 B2 JP 5993337B2 JP 2013097040 A JP2013097040 A JP 2013097040A JP 2013097040 A JP2013097040 A JP 2013097040A JP 5993337 B2 JP5993337 B2 JP 5993337B2
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智 時田
智 時田
間所　靖
靖 間所
江口　邦彦
邦彦 江口
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Description

本発明は、鱗片状黒鉛粒子、焼成炭素、およびリチウムと合金化可能な金属粒子からなるリチウムイオン二次電池用負極材料用複合粒子およびその製造方法ならびにこれを用いたリチウムイオン二次電池用負極ならびにその負極を用いたリチウムイオン二次電池に関する。   The present invention relates to composite particles for negative electrode materials for lithium ion secondary batteries, comprising flaky graphite particles, calcined carbon, and metal particles that can be alloyed with lithium, a method for producing the same, and a negative electrode for lithium ion secondary batteries using the same The present invention also relates to a lithium ion secondary battery using the negative electrode.

リチウムイオン二次電池は、他の二次電池に比べて高電圧、高エネルギー密度という優れた特性を有するため、電子機器の電源として広く普及している。近年、電子機器の小型化および高性能化が進み、リチウムイオン二次電池のさらなる高エネルギー密度化に対する要望はますます高まっている。
現在リチウムイオン二次電池は、正極にＬｉＣｏＯ２、負極に黒鉛を用いたものが一般的である。しかし、黒鉛負極は充放電の可逆性に優れるものの、その放電容量はすでに層間化合物ＬｉＣ６に相当する理論値３７２ｍＡｈ／ｇに近い値まで到達しており、さらなる高エネルギー密度化を達成するためには、黒鉛より放電容量の大きい負極材料を開発する必要がある。
金属リチウムは負極材料として最高の放電容量を有するが、充電時にリチウムがデンドライト状に析出して負極が劣化し、充放電サイクルが短くなるという問題がある。また、デンドライト状に析出したリチウムがセパレータを貫通して正極に達し、短絡する可能性もある。
そのため、金属リチウムに替わる負極材料として、リチウムと合金を形成する金属質物が検討されてきた。これらの合金負極は、金属リチウムには及ばないものの黒鉛を遥かに凌ぐ放電容量を有する。しかし、合金化に伴う体積膨張により活物質の粉化、剥離が発生し、未だ実用レベルのサイクル特性は得られていない。 Lithium ion secondary batteries have excellent characteristics such as high voltage and high energy density compared to other secondary batteries, and are therefore widely used as power sources for electronic devices. In recent years, electronic devices have been reduced in size and performance, and there has been an increasing demand for further increase in energy density of lithium ion secondary batteries.
Currently, lithium ion secondary batteries generally use LiCoO 2 for the positive electrode and graphite for the negative electrode. However, although the graphite negative electrode is excellent in reversibility of charge and discharge, its discharge capacity has already reached a value close to the theoretical value 372 mAh / g corresponding to the intercalation compound LiC 6 in order to achieve further higher energy density. Needs to develop a negative electrode material having a larger discharge capacity than graphite.
Although metallic lithium has the highest discharge capacity as a negative electrode material, there is a problem that lithium is deposited in a dendritic state during charging, the negative electrode is deteriorated, and the charge / discharge cycle is shortened. In addition, lithium deposited in a dendrite shape may penetrate the separator and reach the positive electrode, causing a short circuit.
Therefore, metallic materials that form an alloy with lithium have been studied as negative electrode materials that replace metallic lithium. These alloy negative electrodes have discharge capacities far surpassing that of graphite, although they do not reach metal lithium. However, the active material is pulverized and peeled off due to volume expansion accompanying alloying, and the practical cycle characteristics have not yet been obtained.

前述のような合金負極の欠点を改善するため、金属質物と、黒鉛質物または炭素質物のどちらか一方または両方との複合化が検討されている。大別すると金属質物、黒鉛質物、炭素質物前駆体を混合後、熱処理するもの（特許文献１）（２）ＣＶＤ法を用いて金属質物に炭素質層を被覆するもの（特許文献２）（３）上記（２）にメカニカルアロイングを併用するもの（特許文献３）などである。しかしながら上記（１）〜（３）のいずれにおいても、金属質物の周囲に黒鉛質物や炭素質物を単に配するだけでは、充電時の金属質物の膨張を充分に緩和できないため、活物質の微粉化や剥離といった問題を解決するには至らず、実用レベルのサイクル特性を得られていないのが現状である。   In order to improve the drawbacks of the above-described alloy negative electrode, a composite of a metal material and one or both of a graphitic material and a carbonaceous material has been studied. When roughly classified, a metal material, a graphite material, and a carbonaceous material precursor are mixed and then heat-treated (Patent Document 1) (2) A metal material is coated with a carbonaceous layer using a CVD method (Patent Document 2) (3 ) (2) using mechanical alloying together (Patent Document 3). However, in any of the above (1) to (3), since the expansion of the metallic material during charging cannot be sufficiently eased simply by arranging the graphite or carbonaceous material around the metallic material, the active material is pulverized. The present situation is that it has not been able to solve problems such as peeling and peeling, and has not yet achieved a practical level of cycle characteristics.

特許文献４では、平均粒径が２〜５μｍで、アスペクト比が３以下である黒鉛質粒子表面に、該黒鉛質粒子の平均粒径の１／２以下の平均粒径である、リチウムと合金化可能な金属粒子をメカノケミカル処理して付着させた後、該メカノケミカル処理物を樹脂などで造粒（例えばスプレードライ）し、該造粒物に炭素質前駆体を含浸させ、６００℃以上で熱処理して、金属−黒鉛質系粒子を製造する金属−黒鉛質系粒子の製造方法が記載されている。   In Patent Document 4, lithium and an alloy having an average particle diameter of 2 to 5 μm and an average particle diameter of 1/2 or less of the average particle diameter of the graphite particles on the surface of the graphite particles having an aspect ratio of 3 or less. The mechanochemically treated metal particles are adhered by mechanochemical treatment, and then the mechanochemically treated product is granulated with a resin or the like (for example, spray-dried), and the granulated product is impregnated with a carbonaceous precursor and 600 ° C. or higher Describes a method for producing metal-graphitic particles, which is heat-treated to produce metal-graphitic particles.

特開２００２−２３１２２５号公報JP 2002-231225 A 特開２００２−１５１０６６号公報JP 2002-151066 A 特開２００２−２１６７５１号公報Japanese Patent Laid-Open No. 2002-216751 特開２００６−２９４４７６号公報JP 2006-294476 A

本発明は、上記のような状況を鑑みてなされたものであり、負極材料を特定の構造にすることにより、金属物質である例えばＳｉが膨張、収縮を繰り返してもサイクル特性の低下を防止できることを発明した。この負極材料をリチウムイオン二次電池負極材料として用いて、充電時の金属質物の膨張を充分に緩和でき、黒鉛の理論容量を超える高い放電容量と、優れた初期充放電効率およびサイクル特性を示す材料を提供することを目的とする。また、得られた負極材料を用いてなるリチウムイオン二次電池用負極および該二次電池用負極を用いたリチウムイオン二次電池を提供することが目的である。   The present invention has been made in view of the above situation, and by making the negative electrode material have a specific structure, it is possible to prevent deterioration of cycle characteristics even when a metal material such as Si repeatedly expands and contracts. Was invented. Using this negative electrode material as a negative electrode material for lithium ion secondary batteries, the expansion of the metal material during charging can be sufficiently relaxed, and it exhibits a high discharge capacity exceeding the theoretical capacity of graphite, and excellent initial charge / discharge efficiency and cycle characteristics. The purpose is to provide material. It is another object of the present invention to provide a negative electrode for a lithium ion secondary battery using the obtained negative electrode material and a lithium ion secondary battery using the negative electrode for a secondary battery.

前記課題を解決するため、本発明は、鱗片状黒鉛粒子と、リチウムと合金化可能な金属粒子からなる球状もしくは略球状の複合体であって、前記複合体は少なくとも内部に空隙を有し、前記鱗片状黒鉛粒子が前記複合体の内部では非平行に存在し、前記複合体の表面では同心円状に配向して存在し、かつ前記金属粒子が該複合体粒子内に分散して存在する負極材料を提供する。   In order to solve the above problems, the present invention is a spherical or substantially spherical composite composed of scaly graphite particles and metal particles that can be alloyed with lithium, and the composite has at least voids therein, The negative electrode in which the scaly graphite particles are present non-parallelly inside the composite, are present in a concentric orientation on the surface of the composite, and the metal particles are dispersed in the composite particles Provide material.

すなわち本発明は、以下を提供する。
（１）鱗片状黒鉛粒子、焼成炭素およびリチウムと合金化可能な金属粒子からなる球状の複合体であって、前記複合体が内部に空隙を有し、かつ前記鱗片状黒鉛粒子が前記複合体の内部では、該内部に存在する鱗片状黒鉛粒子の総数の９０％以上が非平行に存在し、前記複合体の表面では同心円状に配向して存在し、かつ、前記金属粒子が前記複合体粒子内部および／または表面に分散して存在するリチウムイオン二次電池用負極材料で、前記負極材料の、水銀圧入法で測定した０．０１〜１００μｍの大きさの空隙の容積が、０．０５〜０．４ｃｍ ３ ／ｇであるに記載のリチウムイオン二次電池用負極材料。
（２）前記複合体を１００質量％として、前記鱗片状黒鉛粒子：９８〜６０質量％、前記焼成炭素：１〜２０質量％、および前記金属粒子：１〜２０質量％である（１）に記載のリチウムイオン二次電池用負極材料。
（３）前記複合体に、さらに黒鉛質繊維を含む（１）または（２）に記載のリチウムイオン二次電池用負極材料。
（４）前記複合体を１００質量％として、前記鱗片状黒鉛粒子：９７．５〜５５質量％、
前記焼成炭素：１〜２０質量％、前記金属粒子：１〜２０質量％、および
前記黒鉛質繊維：０．５〜５質量％である（３）に記載のリチウムイオン二次電池用負極材料。
（５）前記鱗片状黒鉛粒子の平均偏平度（Ｌｙ／ｔ）が、０．５〜４０である（１）ないし（４）のいずれか１項に記載のリチウムイオン二次電池用負極材料。
（６）上記（１）ないし（４）のいずれか１項に記載のリチウムイオン二次電池用負極材料を含有するリチウムイオン二次電池用負極。
（７）上記（６）に記載のリチウムイオン二次電池用負極を有するリチウムイオン二次電池。
（８）鱗片状黒鉛粒子、焼成炭素およびリチウムと合金化可能な金属粒子からなる球状の複合体の製造方法であって、前記鱗片状黒鉛粒子および前記金属粒子を炭素質材料および／または炭素質材料の前駆体である結着剤の溶液に固形分濃度５〜２５質量％で分散させ、噴霧乾燥処理した後、７００℃以上、１５００℃以下の温度範囲で熱処理を行い、前記した炭素質材料および炭素質材料の前駆体を焼成炭素とし、その後粉砕工程を経ずに最終製品とし、前記最終製品が、鱗片状黒鉛粒子、焼成炭素およびリチウムと合金化可能な金属粒子からなる球状の複合体であって、前記複合体が内部に空隙を有し、かつ前記鱗片状黒鉛粒子が前記複合体の内部では非平行に存在し、前記複合体の表面では同心円状に配向して存在し、かつ、前記金属粒子が前記複合体粒子内部および／または表面に分散して存在することを特徴とするリチウムイオン二次電池用負極材の製造方法。
（９）鱗片状黒鉛粒子、焼成炭素、リチウムと合金化可能な金属粒子および黒鉛質繊維からなる球状の複合体の製造方法であって、前記鱗片状黒鉛粒子、前記金属粒子および黒鉛質繊維を炭素質材料および／または炭素質材料の前駆体である結着剤の溶液に固形分濃度５〜２５質量％で分散させ、噴霧乾燥処理した後、７００℃以上、１５００℃以下の温度範囲で熱処理を行い、前記した炭素質材料および炭素質材料の前駆体を焼成炭素とし、その後粉砕工程を経ずに最終製品とし、
前記最終製品が、鱗片状黒鉛粒子、焼成炭素およびリチウムと合金化可能な金属粒子からなる球状の複合体であって、前記複合体が内部に空隙を有し、かつ前記鱗片状黒鉛粒子が前記複合体の内部では非平行に存在し、前記複合体の表面では同心円状に配向して存在し、かつ、前記金属粒子が前記複合体粒子内部および／または表面に分散して存在する
ことを特徴とするリチウムイオン二次電池用負極材の製造方法。
（１０）前記噴霧乾燥処理品に、さらに炭素質材料および／または炭素質材料の前駆体を付着させた後、前記熱処理を行うことを特徴とする（８）または（９）に記載のリチウムイオン二次電池用負極材の製造方法。
（１１）前記最終製品の、水銀圧入法で測定した０．０１〜１００μｍの大きさの空隙の容積が、０．０５〜０．４ｃｍ ３ ／ｇである請求項８ないし１０のいずれか１項に記載のリチウムイオン二次電池用負極材料の製造方法。
That is, the present invention provides the following.
(1) A spherical composite composed of scaly graphite particles, calcined carbon and metal particles that can be alloyed with lithium, wherein the composite has voids therein, and the scaly graphite particles are the composite 90% or more of the total number of flaky graphite particles present in the interior is non-parallel, and is present in a concentric orientation on the surface of the composite, and the metal particles are the composite A negative electrode material for a lithium ion secondary battery that is dispersed in and / or on the surface of a particle, the negative electrode material having a void volume of 0.01 to 100 μm measured by a mercury intrusion method is 0.05. The negative electrode material for lithium ion secondary batteries as described in -0.4cm < 3 > / g.
(2) The composite is 100% by mass, and the scale-like graphite particles are 98 to 60% by mass, the calcined carbon is 1 to 20% by mass, and the metal particles are 1 to 20% by mass (1). The negative electrode material for lithium ion secondary batteries as described.
(3) The negative electrode material for a lithium ion secondary battery according to (1) or (2) , wherein the composite further contains a graphite fiber.
(4) The composite is 100% by mass, the scaly graphite particles: 97.5 to 55% by mass,
The negative electrode material for a lithium ion secondary battery according to (3) , wherein the calcined carbon is 1 to 20% by mass, the metal particles are 1 to 20% by mass, and the graphite fiber is 0.5 to 5% by mass.
(5) The negative electrode material for a lithium ion secondary battery according to any one of (1) to (4) , wherein an average flatness (Ly / t) of the scaly graphite particles is 0.5 to 40 .
(6) A negative electrode for a lithium ion secondary battery comprising the negative electrode material for a lithium ion secondary battery according to any one of (1) to (4 ) above.
(7) The lithium ion secondary battery which has a negative electrode for lithium ion secondary batteries as described in said (6) .
(8) A method for producing a spherical composite comprising scaly graphite particles, calcined carbon, and metal particles that can be alloyed with lithium, wherein the scaly graphite particles and the metal particles are carbonaceous material and / or carbonaceous. The carbonaceous material described above is dispersed in a binder solution, which is a precursor of the material, at a solid content concentration of 5 to 25% by mass , spray-dried, and then heat-treated at a temperature range of 700 ° C. to 1500 ° C. And a precursor of carbonaceous material is calcined carbon, and then the final product is obtained without going through a pulverization step, and the final product is a spherical composite composed of scaly graphite particles, calcined carbon and metal particles that can be alloyed with lithium. The composite has voids therein, and the scaly graphite particles exist non-parallel inside the composite, and exist in a concentric orientation on the surface of the composite , And the metal Method of preparing a negative electrode material for a lithium ion secondary battery, characterized by the child is present dispersed in the composite particles inside and / or surface.
(9) A method for producing a spherical composite comprising scaly graphite particles, calcined carbon, metal particles that can be alloyed with lithium, and graphite fibers, wherein the scaly graphite particles, the metal particles, and the graphite fibers are After being dispersed in a carbonaceous material and / or a binder solution which is a precursor of the carbonaceous material at a solid content concentration of 5 to 25% by mass and spray-dried, heat treatment is performed at a temperature range of 700 ° C. to 1500 ° C. The carbonaceous material and the precursor of the carbonaceous material described above are calcined carbon, and then the final product without a pulverization step ,
The final product is a spherical composite composed of scaly graphite particles, metal particles that can be alloyed with calcined carbon and lithium, the composite has voids inside, and the scaly graphite particles are It exists non-parallel inside the composite, exists in a concentric orientation on the surface of the composite , and the metal particles are dispersed inside and / or on the surface of the composite particles.
The manufacturing method of the negative electrode material for lithium ion secondary batteries characterized by the above-mentioned .
(10) The lithium ion according to (8) or (9) , wherein the heat treatment is performed after further attaching a carbonaceous material and / or a precursor of the carbonaceous material to the spray-dried product. A method for producing a negative electrode material for a secondary battery.
(11) wherein the final product, the void volume of the size of 0.01~100μm measured by mercury porosimetry, any one of claims 8 are 0.05~0.4cm 3 / g 10 The manufacturing method of the negative electrode material for lithium ion secondary batteries as described in 2 ..

本発明の負極材料である複合体は、リチウムイオン二次電池用負極材料に用いた場合に、充電時の金属質物の膨張を充分に緩和でき、黒鉛の理論容量を超える高い放電容量と、優れた初期充放電効率を示す。   The composite that is the negative electrode material of the present invention, when used as a negative electrode material for lithium ion secondary batteries, can sufficiently relax the expansion of the metallic material during charging, has a high discharge capacity that exceeds the theoretical capacity of graphite, Initial charge and discharge efficiency.

実施例１で得られた複合体の外観を示す電子顕微鏡写真（３０００倍）である。2 is an electron micrograph (magnification 3000 times) showing the appearance of the composite obtained in Example 1. FIG. 実施例１で得られた複合体の断面の偏光顕微鏡写真（３０００倍）である。2 is a polarizing microscope photograph (magnified 3000 times) of a cross section of the composite obtained in Example 1. FIG. 実施例１で得られた複合体の外表面に存在するエネルギー分散型Ｘ線分光法で測定されるＳｉ元素を示すＥＤＸマッピング像（３０００倍）である。2 is an EDX mapping image (3000 times) showing Si element measured by energy dispersive X-ray spectroscopy existing on the outer surface of the composite obtained in Example 1. FIG. 本発明の負極の電池特性を評価するための評価電池の断面図である。It is sectional drawing of the evaluation battery for evaluating the battery characteristic of the negative electrode of this invention.

〔負極材料：鱗片状黒鉛粒子、焼成炭素およびリチウムと合金化可能な金属粒子からなる球状の複合体〕
本発明は、鱗片状黒鉛粒子、焼成炭素およびリチウムと合金化可能な金属粒子からなる球状もしくは略球状の複合体であって、前記複合体は少なくとも内部に空隙を有し、前記鱗片状黒鉛粒子が前記複合体の内部では非平行に存在し、前記複合体の表面では同心円状に配向して存在し、かつ前記金属粒子が該複合体粒子内部および／または表面に分散して存在する負極材料を提供する。本明細書では、「複合粒子内部および／または表面に分散する」ことを「複合粒子内に分散する」ということがある。
複合体が内部に空隙を有する構造であることで、合金化に伴う体積の膨張を吸収し、活物質の粉化や剥離を防ぐことができる。また、鱗片状黒鉛粒子が複合体の表面で同心円状に配向している構造であることで、表面に露出するのは反応性の比較的低いベーサル面となり、エッジ面の露出に由来する充放電効率やサイクル特性の低下を引き起こすことがない。
複合体の形状についてより具体的には、複合体の平均アスペクト比が３以下であることが好ましく、２以下であることが特に好ましい。平均アスペクト比が３より大きい場合にはサイクル特性が悪化することがある。なおアスペクト比は、複合体１粒子の長軸長の短軸長に対する比を意味し、走査型電子顕微鏡によって任意の１００個の粒子を観察して測定した各粒子のアスペクト比の算術平均値を、平均アスペクト比とする。 [Negative electrode material: Spherical graphite particles, spherical composites composed of calcined carbon and metal particles that can be alloyed with lithium]
The present invention is a spherical or substantially spherical composite comprising scaly graphite particles, metal particles that can be alloyed with calcined carbon and lithium, and the composite has at least a void inside, and the scaly graphite particles Is present in a non-parallel manner inside the composite, is present in a concentric orientation on the surface of the composite, and the metal particles are dispersed in and / or on the surface of the composite particles. I will provide a. In the present specification, “dispersing in the composite particle and / or on the surface” is sometimes referred to as “dispersing in the composite particle”.
When the composite has a structure having voids inside, the expansion of the volume accompanying alloying can be absorbed, and powdering and peeling of the active material can be prevented. In addition, because the scaly graphite particles are concentrically oriented on the surface of the composite, what is exposed on the surface is a basal surface with relatively low reactivity, and charge / discharge resulting from exposure of the edge surface There is no reduction in efficiency or cycle characteristics.
More specifically, regarding the shape of the composite, the average aspect ratio of the composite is preferably 3 or less, and particularly preferably 2 or less. If the average aspect ratio is greater than 3, the cycle characteristics may deteriorate. The aspect ratio means the ratio of the major axis length to the minor axis length of one particle of the composite, and the arithmetic average value of the aspect ratio of each particle measured by observing arbitrary 100 particles with a scanning electron microscope. The average aspect ratio.

複合体の平均粒子径は１〜５０μｍの範囲であることが好ましく、５〜３０μｍの範囲であることがさらに好ましい。本発明において、複合体の平均粒子径はレーザー回折式粒度分布計の累積度数が体積分布率で５０％となる粒子径（Ｄ５０）である。
本発明の負極材料は、前記特徴を達成し得る方法であれば、いかなる方法で製造されたものでもよい。また、異種の黒鉛材料、炭素質または黒鉛質の繊維、非晶質ハードカーボンなどの炭素材料、有機材料、無機材料、金属材料との混合物、複合物であってもよい。
複合体内部の空隙については、その形状や存在状態は限定されず、分散して存在していてもよいし、中心付近に存在していてもよいし、複合体の表面まで到達していてもよい。
特に複合体は内部に黒鉛質繊維を含んでいることがより望ましい。黒鉛質繊維は、複合体内部の空隙を潰すことなく、鱗片状黒鉛粒子や金属粒子同士を電気的に接続する役割を持ち、複合体の電気抵抗を低減しサイクル特性を向上させる。
また水銀圧入法で測定した０．０１〜１００μｍの大きさの空隙の容積は、０．０５〜０．４ｃｍ３／ｇであることが好ましい。
この範囲の空隙は、その内部に電解液を適切に保持でき、本発明の負極材料を用いるリチウム二次電池の急速充放電特性を向上させる。
複合体表面における鱗片状黒鉛粒子の存在状態については、ＳＥＭ（走査型電子顕微鏡）観察で確認することができる。複合体内部における鱗片状黒鉛粒子の存在状態については、樹脂に埋め込んだ複合体粒子を研磨したのちＳＥＭまたは偏光顕微鏡で断面を観察することで確認できる。また、複合体表面および内部における金属粒子の存在状態については、ＥＤＸ（エネルギー分散型Ｘ線分光法）分析により確認することができる。 The average particle size of the composite is preferably in the range of 1 to 50 μm, and more preferably in the range of 5 to 30 μm. In the present invention, the average particle size of the composite is a particle size (D 50 ) at which the cumulative frequency of the laser diffraction particle size distribution meter is 50% by volume distribution.
The negative electrode material of the present invention may be manufactured by any method as long as it can achieve the above characteristics. Further, it may be a heterogeneous graphite material, a carbonaceous or graphite fiber, a carbon material such as amorphous hard carbon, an organic material, an inorganic material, a mixture with a metal material, or a composite.
As for the voids inside the complex, the shape and state of existence thereof are not limited, and may exist in a dispersed manner, may exist near the center, or may reach the surface of the complex. Good.
In particular, it is more desirable that the composite contains graphite fibers inside. The graphite fiber has a role of electrically connecting the scaly graphite particles and the metal particles without crushing the voids inside the composite, and reduces the electrical resistance of the composite and improves the cycle characteristics.
Moreover, it is preferable that the volume of the space | gap with a magnitude | size of 0.01-100 micrometers measured by the mercury intrusion method is 0.05-0.4 cm < 3 > / g.
The voids in this range can appropriately hold the electrolytic solution therein, and improve the rapid charge / discharge characteristics of the lithium secondary battery using the negative electrode material of the present invention.
The existence state of the scaly graphite particles on the composite surface can be confirmed by SEM (scanning electron microscope) observation. The presence state of the scaly graphite particles inside the composite can be confirmed by observing the cross section with an SEM or a polarizing microscope after polishing the composite particles embedded in the resin. In addition, the existence state of the metal particles on the surface and inside of the composite can be confirmed by EDX (energy dispersive X-ray spectroscopy) analysis.

本発明のリチウムイオン二次電池用負極材料は、図１、図３にその一例の外観の走査型電子顕微鏡（以下、ＳＥＭという）写真を示すように、鱗片状黒鉛粒子、焼成炭素およびリチウムと合金化可能な金属粒子からなる球状の複合体である。また複合体内部における鱗片状黒鉛粒子の存在状態については、樹脂に埋め込んだ複合体粒子を研磨したのち走査型顕微鏡（ＳＥＭ）または偏光顕微鏡で断面を観察することで確認できる。図２にその一例の内部の偏光顕微鏡写真を示すように、内部に空隙を有し、かつ鱗片状黒鉛粒子が複合体の内部では非平行に存在し、複合体の表面では鱗片状黒鉛粒子が同心円状に配向して存在する。
ここで複合体の表面とは、複合体の最表面から鱗片状黒鉛の厚さの２倍以下（およそ１μｍ以下）の範囲をいう。内部とは表面以外の範囲をいう。
図２は実施例１で得られた複合体の断面の偏光顕微鏡写真であり、内部の形状がカラーで示されている。出願と同時に上申書で提出する図２のカラー写真で詳細を確認できる。図２で、球状の粒子の中央付近の黒色で示される部分は内部の空隙である。図２で、黒色ではない部分（カラー図では紫または青色）で示される部分は、鱗片状黒鉛粒子が複合体の内部で非平行に存在する状態を示している。非平行に存在するとの意味は内部に存在する鱗片状黒鉛粒子の総数の９０％以上が非平行であることをいう。
図３は、実施例１で得られた複合体の外表面に存在するエネルギー分散型Ｘ線分光法で測定されるＳｉ元素を示すＥＤＸ（エネルギー分散型X線分光法）マッピング像である。図３で白黒の図では表面に黒色の点状に認められる部分がシリコン粒子が分散して存在している状態を示している。出願と同時に上申書で提出する図３のカラー写真で詳細を確認できる。カラー写真では全体が灰色の複合体の表面にシリコン粒子が赤色で点状に示されている。 The negative electrode material for a lithium ion secondary battery of the present invention is composed of scaly graphite particles, calcined carbon and lithium, as shown in FIG. 1 and FIG. A spherical composite made of alloyable metal particles. Further, the presence state of the scaly graphite particles inside the composite can be confirmed by polishing the composite particles embedded in the resin and then observing the cross section with a scanning microscope (SEM) or a polarizing microscope. As shown in FIG. 2 of an example of a polarized micrograph of the interior, there are voids inside, and the scaly graphite particles are non-parallel inside the composite, and the scaly graphite particles are present on the surface of the composite. It exists in a concentric orientation.
Here, the surface of the composite refers to a range of 2 times or less (approximately 1 μm or less) of the thickness of the scaly graphite from the outermost surface of the composite. The inside means a range other than the surface.
FIG. 2 is a polarization micrograph of the cross section of the composite obtained in Example 1, and the internal shape is shown in color. Details can be confirmed in the color photograph shown in Fig. 2 submitted in the application form at the same time as the application. In FIG. 2, the black portion near the center of the spherical particles is an internal void. In FIG. 2, a portion indicated by a portion that is not black (purple or blue in the color diagram) indicates a state in which the scaly graphite particles exist non-parallel inside the composite. The meaning of being non-parallel means that 90% or more of the total number of scaly graphite particles present inside is non-parallel.
FIG. 3 is an EDX (energy dispersive X-ray spectroscopy) mapping image showing Si elements measured by energy dispersive X-ray spectroscopy existing on the outer surface of the composite obtained in Example 1. In the black-and-white diagram in FIG. 3, a portion recognized as black dots on the surface shows a state in which silicon particles are dispersed. Details can be confirmed in the color photograph shown in Fig. 3 submitted in the application form at the same time as the application. In the color photograph, the silicon particles are shown as red dots on the surface of the overall gray composite.

複合体中のリチウムと合金化可能な金属粒子は、複合体粒子に分散して存在している。これは、リチウムと合金化可能な金属粒子が、例えばＳｉの場合、エネルギー分散型Ｘ線分光法で、複合体粒子表面を測定して得られるＳｉの存在頻度と、樹脂に埋め込んだ複合体粒子を研磨したのち断面のＳｉの存在頻度とを測定した場合に、ほぼ同様であることを意味する。本発明の複合体では、リチウムと合金化可能な金属粒子は、複合体粒子の内部および表面に分散している。   Metal particles that can be alloyed with lithium in the composite are present dispersed in the composite particles. This is because, when the metal particles that can be alloyed with lithium are, for example, Si, the presence frequency of Si obtained by measuring the surface of the composite particles by energy dispersive X-ray spectroscopy, and the composite particles embedded in the resin This means that it is almost the same when the presence frequency of Si in the cross section is measured after polishing. In the composite of the present invention, metal particles that can be alloyed with lithium are dispersed inside and on the surface of the composite particles.

［鱗片状黒鉛粒子］
本発明で用いられる鱗片状黒鉛粒子は、リチウムイオンを吸蔵・放出できるものであればよく、特に限定されない。その一部または全部が黒鉛質で形成されているもの、例えば天然黒鉛や、タール、ピッチ類を最終的に１５００℃以上で熱処理してなる人造黒鉛が挙げられる。具体的には、易黒鉛化性炭素材料とよばれる石油系、石炭系のタールピッチ類を熱処理して重縮合させたメソフェーズ焼成体、コークス類を１５００℃以上、望ましくは２８００〜３３００℃で黒鉛化処理して得ることができる。 [Scaly graphite particles]
The scaly graphite particles used in the present invention are not particularly limited as long as they can occlude and release lithium ions. A part or all of which is made of graphite, for example, natural graphite, and artificial graphite obtained by finally heat-treating tar and pitch at 1500 ° C. or higher. Specifically, mesophase fired bodies obtained by heat-condensing petroleum-based and coal-based tar pitches called carbonitizable carbon materials and subjected to polycondensation, and cokes are graphite at 1500 ° C. or higher, preferably 2800-3300 ° C. It can be obtained by the chemical treatment.

本発明の鱗片状黒鉛粒子の平均粒子径は０．１μｍ〜２０μｍの範囲であることが好ましく、０．３μｍ〜１０μｍの範囲であることがさらに好ましい。鱗片状黒鉛粒子の平均粒子径は上記複合体の場合と同様にＤ５０である。形状が鱗片状の場合の平均粒子径は、その粒子と同一体積の球状粒子の平均粒子径に換算した値とする。
また、前記鱗片状黒鉛粒子の平均偏平度（Ｌｙ／ｔ）が、０．５以上であるのが好ましく、２〜４０であるのがより好ましい。ここで平均偏平度とは、鱗片状黒鉛粒子の１粒子の厚さｔの短軸長Ｌｙに対する比（Ｌｙ／ｔ）を意味し、走査型電子顕微鏡によって１００個の鱗片状黒鉛粒子を観察して測定した各粒子の偏平度の単純平均値として算出する。
また、液相、気相、固相における各種化学的処理、熱処理、酸化処理、物理的処理などを施したものであってもよい。
鱗片状黒鉛粒子の割合は、複合体粒子全量に対して９８〜６０質量％であるのが好ましい。より好ましくは９５〜６０質量％である。
本発明の負極材料の複合体の表面に露出するのは鱗片状黒鉛粒子の反応性の比較的低いベーサル面（ＡＢ面）であり、上述したようなエッジ面の露出に由来する充放電効率やサイクル特性の低下を引き起こすことがない。 The average particle diameter of the scaly graphite particles of the present invention is preferably in the range of 0.1 μm to 20 μm, and more preferably in the range of 0.3 μm to 10 μm. The average particle diameter of the scaly graphite particles is D 50 as in the case of the complex. The average particle diameter when the shape is scale-like is a value converted to the average particle diameter of spherical particles having the same volume as the particles.
The average flatness (Ly / t) of the scaly graphite particles is preferably 0.5 or more, more preferably 2 to 40. Here, the average flatness means the ratio (Ly / t) of the thickness t of one scaly graphite particle to the short axis length Ly, and 100 scaly graphite particles were observed with a scanning electron microscope. It is calculated as a simple average value of the flatness of each particle measured in the above.
Further, it may be subjected to various chemical treatments in the liquid phase, gas phase, and solid phase, heat treatment, oxidation treatment, physical treatment and the like.
The ratio of the scale-like graphite particles is preferably 98 to 60% by mass with respect to the total amount of the composite particles. More preferably, it is 95-60 mass%.
Exposed on the surface of the composite of the negative electrode material of the present invention is the basal surface (AB surface) having relatively low reactivity of the scaly graphite particles, and the charge / discharge efficiency derived from the exposure of the edge surface as described above Does not cause deterioration of cycle characteristics.

［焼成炭素］
本発明で用いられる焼成炭素は、前記鱗片状黒鉛粒子を下記の結着剤と混合した分散液を噴霧乾燥処理して、その後焼成して得られる複合体中に黒鉛粒子と別に存在する炭素成分で、前駆体としての結着剤、溶液が焼成された焼成炭素、または、噴霧乾燥処理品を下記の結着剤を含浸させた後、焼成された焼成炭素である。以下のいかなる前駆体に由来してもよく、タールピッチ類および／または樹脂類が例示される。具体的には、タールピッチ類としては、コールタール、タール軽油、タール中油、タール重油、ナフタリン油、アントラセン油、コールタールピッチ、ピッチ油、メソフェーズピッチ、酸素架橋石油ピッチ、ヘビーオイルなどが挙げられる。樹脂類としては、ポリビニルアルコール、ポリアクリル酸、ポリ塩化ビニル、ポリ塩化ビニリデン、塩素化ポリ塩化ビニルなどのハロゲン化ビニル樹脂などの熱可塑性樹脂、フェノール樹脂、フラン樹脂、フルフリルアルコール樹脂、セルロース樹脂、ポリアクリロニトリル、ポリアミドイミド樹脂、ポリアミド樹脂などの熱硬化性樹脂が例示される。これらの炭素質物前駆体を後述の温度で熱処理することにより焼成炭素を得ることができる。
焼成炭素は黒鉛化しておらず、非晶質であることが好ましい。
焼成炭素の製品複合体中の含有量は、１〜２０質量％が好ましい。１〜１５質量％であるのがより好ましい。 [Calcined carbon]
The calcined carbon used in the present invention is a carbon component that exists separately from the graphite particles in a composite obtained by spray-drying a dispersion obtained by mixing the above scaly graphite particles with the following binder and then firing the dispersion. Thus, a binder as a precursor, a calcined carbon obtained by firing a solution, or a fired carbon obtained by impregnating a spray-dried product with the following binder, followed by firing. It may be derived from any of the following precursors, and tar pitches and / or resins are exemplified. Specifically, the tar pitches include coal tar, tar light oil, tar medium oil, tar heavy oil, naphthalene oil, anthracene oil, coal tar pitch, pitch oil, mesophase pitch, oxygen-crosslinked petroleum pitch, heavy oil, and the like. . Examples of resins include polyvinyl alcohol, polyacrylic acid, polyvinyl chloride, polyvinylidene chloride, thermoplastic resins such as vinyl halide resins such as chlorinated polyvinyl chloride, phenol resins, furan resins, furfuryl alcohol resins, and cellulose resins. And thermosetting resins such as polyacrylonitrile, polyamideimide resin, and polyamide resin. A calcined carbon can be obtained by heat-treating these carbonaceous material precursors at a temperature described below.
The calcined carbon is preferably not amorphous and amorphous.
The content of the baked carbon in the product composite is preferably 1 to 20% by mass. It is more preferably 1 to 15% by mass.

［リチウムと合金化可能な金属粒子］
リチウムと合金化可能な金属粒子としては、Ａｌ、Ｐｂ、Ｚｎ、Ｓｎ、Ｂｉ、Ｉｎ、Ｍｇ、Ｇａ、Ｃｄ、Ａｇ、Ｓｉ、Ｂ、Ａｕ、Ｐｔ、Ｐｄ、Ｓｂ、Ｇｅ、Ｎｉ等の金属粒子が挙げられ、好ましくはＳｉ粒子、Ｓｎ粒子である。また前記金属粒子は上記金属の二種以上の合金であってもよく、合金中に上述の金属以外にさらに他の元素を含有していてもよい。前記金属粒子の一部が、酸化物、窒化物、炭化物を形成していてもよく、特に酸化物を少なくとも一部含むことが好ましい。
本発明に用いる前記金属粒子の割合は、複合粒子全量に対して１質量％以上、２０質量％であるのが好ましく、２質量％以上２０質量％以下であるのが特に好ましい。前記金属粒子が１質量％未満の場合は容量向上の効果が小さくなることがあり、２０質量％超の場合はサイクル特性の改良効果が小さくなることがある。
前記金属粒子の平均粒径は１０μｍ以下であるのが好ましく、５μｍ以下であるのがより好ましく、１μｍ以下であるのが特に好ましい。前記金属粒子の平均粒径が１０μｍを超える場合はサイクル特性の改良効果が小さくなることがある。
前記金属粒子の形状には特に制約はない。粒状、球状、板状、鱗片状、針状、糸状などのいずれであってもよい。 [Metal particles that can be alloyed with lithium]
Metal particles that can be alloyed with lithium include metal particles such as Al, Pb, Zn, Sn, Bi, In, Mg, Ga, Cd, Ag, Si, B, Au, Pt, Pd, Sb, Ge, and Ni. Si particles and Sn particles are preferable. Moreover, the said metal particle may be 2 or more types of alloys of the said metal, and may contain other elements other than the above-mentioned metal in an alloy. Part of the metal particles may form an oxide, a nitride, or a carbide, and preferably includes at least a part of the oxide.
The ratio of the metal particles used in the present invention is preferably 1% by mass or more and 20% by mass, and particularly preferably 2% by mass or more and 20% by mass or less, based on the total amount of the composite particles. When the amount of the metal particles is less than 1% by mass, the effect of improving the capacity may be small, and when the amount is more than 20% by mass, the effect of improving the cycle characteristics may be small.
The average particle size of the metal particles is preferably 10 μm or less, more preferably 5 μm or less, and particularly preferably 1 μm or less. When the average particle diameter of the metal particles exceeds 10 μm, the effect of improving the cycle characteristics may be reduced.
There is no restriction | limiting in particular in the shape of the said metal particle. Any of a granular shape, a spherical shape, a plate shape, a scale shape, a needle shape, a thread shape and the like may be used.

〔黒鉛質繊維〕
黒鉛質繊維は導電性を有する繊維状の黒鉛であればよく、特に限定されない。好ましい形状は、平均繊維径１０〜１０００ｎｍ、平均繊維長１〜２０μｍであり、カーボンナノチューブ、カーボンナノファイバー、気相成長炭素繊維などが例示される。
黒鉛質繊維の割合は、複合粒子全量に対して０．５質量％以上、５質量％以下であるのが好ましく、１質量％以上、３質量％以下であることがより好ましい。黒鉛質繊維が０．５質量％未満の場合はサイクル特性向上の効果が小さくなることがあり、５質量％超の場合は初期充放電効率が低下することがある。 [Graphite fiber]
The graphite fiber may be fibrous graphite having conductivity, and is not particularly limited. Preferred shapes are an average fiber diameter of 10 to 1000 nm and an average fiber length of 1 to 20 μm, and examples include carbon nanotubes, carbon nanofibers, and vapor grown carbon fibers.
The ratio of the graphite fiber is preferably 0.5% by mass or more and 5% by mass or less, and more preferably 1% by mass or more and 3% by mass or less with respect to the total amount of the composite particles. When the graphite fiber is less than 0.5% by mass, the effect of improving the cycle characteristics may be reduced, and when it exceeds 5% by mass, the initial charge / discharge efficiency may be decreased.

〔複合体の製造方法〕
本発明は、鱗片状黒鉛粒子、焼成炭素、およびリチウムと合金化可能な金属粒子（以下金属粒子ということがある）からなる球状の複合体の製造方法である。焼成炭素は、前記鱗片状黒鉛粒子および金属粒子と結着剤またはその溶液とを混合して噴霧乾燥し、その後焼成して（噴霧乾燥→焼成）焼成炭素としてもよく、鱗片状黒鉛粒子および金属粒子を結着剤またはその溶液中に分散して噴霧乾燥し、その後結着剤としての炭素材料前駆体またはその溶液を混合して焼成して（噴霧乾燥→炭素被覆→焼成）焼成炭素としてもよく、両者を組合せてもよい。また、黒鉛質繊維を加える場合は、鱗片状黒鉛粒子および金属粒子とともに結着剤またはその溶液に分散させ、噴霧乾燥に供することが好ましい。なお、金属粒子と黒鉛質繊維を、あらかじめ鱗片状黒鉛粒子に付着させておいてもよい。本発明の複合体は、焼成処理後粉砕工程を経ずに最終製品とする製造方法で得られることが好ましい。結着剤としては、炭素質材料および／または炭素質材料の前駆体である。前記焼成炭素の前駆体として例示したものと同一である。適当な溶媒に溶解するものであればいかなる結着剤でもよく、前記焼成炭素の前駆体として例示したタールピッチ類および／または樹脂類が例示される。結着剤の原料としての添加量は鱗片状黒鉛粒子１００質量％に対して１〜３０質量％が好ましい。より好ましくは、１〜１５質量％である。結着剤の溶液として用いられるのは水溶液、アルコール溶液、有機溶媒溶液等いずれでもよい。水に界面活性剤、粘度調製剤としてのポリビニルアルコール等を加えた溶液が好ましい。 [Production method of composite]
The present invention is a method for producing a spherical composite comprising scaly graphite particles, calcined carbon, and metal particles that can be alloyed with lithium (hereinafter sometimes referred to as metal particles). The calcined carbon may be a calcined carbon obtained by mixing the above-mentioned scaly graphite particles and metal particles with a binder or a solution thereof, spray drying, and then calcining (spray drying → firing). Particles are dispersed in a binder or a solution thereof and spray-dried, and then a carbon material precursor as a binder or a solution thereof is mixed and fired (spray-drying → carbon coating → firing) to obtain calcined carbon. Well, you may combine both. Moreover, when adding a graphite fiber, it is preferable to disperse | distribute to a binder or its solution with a scaly graphite particle and a metal particle, and to use for spray drying. The metal particles and the graphite fibers may be previously attached to the scaly graphite particles. The composite of the present invention is preferably obtained by a production method for producing a final product without undergoing a pulverization step after firing. The binder is a carbonaceous material and / or a precursor of a carbonaceous material. The same as those exemplified as the precursor of the calcined carbon. Any binder can be used as long as it dissolves in a suitable solvent, and tar pitches and / or resins exemplified as the precursor of the calcined carbon are exemplified. The addition amount of the binder as a raw material is preferably 1 to 30% by mass with respect to 100% by mass of the scaly graphite particles. More preferably, it is 1-15 mass%. Any of an aqueous solution, an alcohol solution, an organic solvent solution, and the like may be used as the binder solution. A solution obtained by adding a surfactant, polyvinyl alcohol or the like as a viscosity adjusting agent to water is preferable.

噴霧乾燥処理は、鱗片状黒鉛粒子と金属粒子とを結着剤である炭素質材料の前駆体の溶液に分散させ、または鱗片状黒鉛炭素粒子を溶液に分散させた分散液を気流とともにスプレー散布し、熱風によって瞬時に溶媒を乾燥させる方法であれば、いかなる方法でもよい。分散液の表面張力によって乾燥後の粒子は真球状を形成する。焼成前の噴霧乾燥処理で得られる球状粒子をここでは複合体前駆体という。この際、分散液の固形分比や気流の調整によって、スプレーの液滴の中に気泡が介在しないようにすることで、完全な中空構造ではなく、内部にも鱗片状黒鉛粒子が存在した構造を形成することができる。
例えば、分散液の固形分比は全量中の５〜２５質量％、噴霧乾燥器の入口温度は１５０〜２５０℃、ノズル空気量は２０〜１００リットル／分などが好ましい。
噴霧乾燥する溶液に結着剤である炭素材料の前駆体を加えなかった場合は、噴霧乾燥して得られる複合体前駆体を炭素材料の前駆体の溶液に浸漬して炭素被覆する。複合体前駆体と炭素材料の前駆体とを混合して炭素被覆してもよい。
噴霧乾燥処理では、原液の固形分比や気流の調整によって任意の粒度に調整可能であり、最終的に粉砕して粒度調整するという工程は不要である。また主原料として黒鉛粒子を用いているので黒鉛化処理は不要であり、焼成処理だけでリチウムイオン二次電池の負極材料として充分な容量を発現できる。 The spray drying process involves spraying a dispersion of scaly graphite particles and metal particles in a carbonaceous material precursor solution as a binder, or a dispersion of scaly graphite carbon particles dispersed in a solution together with an air stream. Any method may be used as long as the solvent is instantly dried with hot air. Due to the surface tension of the dispersion, the particles after drying form a true sphere. Spherical particles obtained by spray drying before firing are referred to herein as composite precursors. At this time, by adjusting the solid content ratio of the dispersion and the air flow so that bubbles do not intervene in the droplets of the spray, it is not a complete hollow structure, but a structure in which scaly graphite particles existed inside Can be formed.
For example, the solid content ratio of the dispersion is preferably 5 to 25% by mass in the total amount, the inlet temperature of the spray dryer is 150 to 250 ° C., and the nozzle air amount is preferably 20 to 100 liter / min.
When the carbon material precursor as a binder is not added to the solution to be spray dried, the composite precursor obtained by spray drying is immersed in the carbon material precursor solution to coat the carbon. The composite precursor and the carbon material precursor may be mixed and coated with carbon.
In the spray drying treatment, the particle size can be adjusted to an arbitrary particle size by adjusting the solid content ratio of the stock solution and the air flow, and a step of finally pulverizing and adjusting the particle size is unnecessary. In addition, since graphite particles are used as the main raw material, graphitization is not necessary, and sufficient capacity can be developed as a negative electrode material for a lithium ion secondary battery only by firing.

噴霧乾燥処理品（複合体前駆体）を不活性雰囲気中、７００℃以上、１５００℃以下の温度範囲で焼成処理することで複合体が得られる。好ましくは９００℃〜１４００℃である。不活性雰囲気は、Ｎ２、Ａｒ、Ｈｅ、真空雰囲気等およびこれらの混合物を用いることができる。 A composite is obtained by baking the spray-dried product (composite precursor) in a temperature range of 700 ° C. or higher and 1500 ° C. or lower in an inert atmosphere. Preferably it is 900 to 1400 degreeC. As the inert atmosphere, N 2 , Ar, He, a vacuum atmosphere, or the like, or a mixture thereof can be used.

焼成処理の前に、異種の黒鉛材料、炭素質または黒鉛質の繊維、非晶質ハードカーボンなどの炭素材料、有機材料、無機材料、金属材料を付着、埋設、複合してもよい。焼成処理の前に炭素質材料および／または炭素質材料の前駆体の溶液中に噴霧乾燥処理品を浸漬して、炭素質材料および／または炭素質材料の前駆体を噴霧乾燥品に付着させてもよい。これは、造粒構造の強化、および被覆により反応性（充放電ロス）を低減させることができる。好ましい付着量（焼成前の量）は鱗片状黒鉛粒子１００質量％に対して１〜３０質量％が好ましい。より好ましくは、１〜１５質量％である。   Prior to the firing treatment, different types of graphite materials, carbonaceous or graphite fibers, carbon materials such as amorphous hard carbon, organic materials, inorganic materials, and metal materials may be attached, embedded, and combined. Before the firing treatment, the spray-dried product is immersed in a solution of the carbonaceous material and / or the precursor of the carbonaceous material to adhere the carbonaceous material and / or the precursor of the carbonaceous material to the spray-dried product. Also good. This can reduce the reactivity (charge / discharge loss) by strengthening the granulated structure and coating. A preferable adhesion amount (amount before firing) is preferably 1 to 30% by mass with respect to 100% by mass of the scaly graphite particles. More preferably, it is 1-15 mass%.

［負極］
本発明は前記負極材料を含有するリチウムイオン二次電池用負極であり、また該負極を用いるリチウムイオン二次電池である。
本発明のリチウムイオン二次電池用の負極は、通常の負極の成形方法に準じて作製されるが、化学的、電気化学的に安定な負極を得ることができる方法であれば何ら制限されない。負極の作製時には、本発明の負極材料に結合剤を加えて、予め調製した負極合剤を用いることが好ましい。結合剤としては、電解質に対して、化学的および電気化学的に安定性を示すものが好ましく、例えば、ポリテトラフルオロエチレン、ポリフッ化ビニリデンなどのフッ素系樹脂粉末、ポリエチレン、ポリビニルアルコールなどの樹脂粉末、カルボキシメチルセルロースなどが用いられる。これらを併用することもできる。結合剤は、通常、負極合剤の全量中の１〜２０質量％程度の割合で用いられる。 [Negative electrode]
The present invention is a negative electrode for a lithium ion secondary battery containing the negative electrode material, and a lithium ion secondary battery using the negative electrode.
The negative electrode for a lithium ion secondary battery of the present invention is produced according to a normal negative electrode molding method, but is not limited as long as it is a method capable of obtaining a chemically and electrochemically stable negative electrode. When preparing the negative electrode, it is preferable to use a negative electrode mixture prepared in advance by adding a binder to the negative electrode material of the present invention. As the binder, those showing chemical and electrochemical stability with respect to the electrolyte are preferable. For example, fluorine-based resin powders such as polytetrafluoroethylene and polyvinylidene fluoride, and resin powders such as polyethylene and polyvinyl alcohol Carboxymethyl cellulose and the like are used. These can also be used together. A binder is normally used in the ratio of about 1-20 mass% in the whole quantity of a negative electrode mixture.

より具体的には、まず、本発明の負極材料を分級などにより所望の粒度に調整し、結合剤と混合して得た混合物を溶剤に分散させ、ペースト状にして負極合剤を調製する。すなわち、本発明の負極材料と、結合剤を、水、イソピロピルアルコール、Ｎ−メチルピロリドン、ジメチルホルムアミドなどの溶剤と混合して得たスラリーを、公知の攪拌機、混合機、混練機、ニーダーなどを用いて攪拌混合して、ペーストを調製する。該ペーストを、集電材の片面または両面に塗布し、乾燥すれば、負極合剤層が均一かつ強固に接着した負極が得られる。負極合剤層の膜厚は１０〜２００μｍ、好ましくは２０〜１００μｍである。   More specifically, first, the negative electrode material of the present invention is adjusted to a desired particle size by classification or the like, and a mixture obtained by mixing with a binder is dispersed in a solvent to prepare a negative electrode mixture in the form of a paste. That is, a slurry obtained by mixing the negative electrode material of the present invention and a binder with a solvent such as water, isopropyl alcohol, N-methylpyrrolidone, dimethylformamide, etc. A paste is prepared by stirring and mixing using the above. When the paste is applied to one or both sides of the current collector and dried, a negative electrode in which the negative electrode mixture layer is uniformly and firmly bonded is obtained. The film thickness of the negative electrode mixture layer is 10 to 200 μm, preferably 20 to 100 μm.

また、本発明の負極は、本発明の負極材料と、ポリエチレン、ポリビニルアルコールなどの樹脂粉末を乾式混合し、金型内でホットプレス成型して作製することもできる。
負極合剤層を形成した後、プレス加圧などの圧着を行うと、負極合剤層と集電体との接着強度をより高めることができる。 The negative electrode of the present invention can also be produced by dry-mixing the negative electrode material of the present invention and resin powders such as polyethylene and polyvinyl alcohol and hot pressing in a mold.
When the negative electrode mixture layer is formed and then pressure bonding such as pressurization is performed, the adhesive strength between the negative electrode mixture layer and the current collector can be further increased.

負極の作製に用いる集電体の形状としては、特に限定されることはないが、箔状、メッシュ、エキスパンドメタルなどの網状などである。集電材の材質としては、銅、ステンレス、ニッケルなどが好ましい。集電体の厚みは、箔状の場合で５〜２０μｍ程度であるのが好ましい。
なお、本発明の負極は、本発明の目的を損なわない範囲で、異種の黒鉛質材料、非晶質ハードカーボンなどの炭素質材料、有機物、金属、金属化合物などを混合しても、内包しても、被覆しても、または積層してもよい。 The shape of the current collector used for producing the negative electrode is not particularly limited, but may be a foil shape, a mesh shape, a net shape such as expanded metal, or the like. The material for the current collector is preferably copper, stainless steel, nickel or the like. The thickness of the current collector is preferably about 5 to 20 μm in the case of a foil.
It should be noted that the negative electrode of the present invention can be included even if different types of graphite materials, carbonaceous materials such as amorphous hard carbon, organic substances, metals, metal compounds, and the like are mixed within a range that does not impair the object of the present invention. Alternatively, it may be coated or laminated.

［正極］
正極は、例えば正極材料と結合剤および導電剤よりなる正極合剤を集電体の表面に塗布することにより形成される。正極の材料（正極活物質）は、充分量のリチウムを吸蔵／離脱し得るものを選択するのが好ましい。リチウム含有遷移金属酸化物、遷移金属カルコゲン化物、バナジウム酸化物およびそのリチウム化合物などのリチウム含有化合物、一般式ＭＸＭｏ６ＯＳ８−Ｙ（式中Ｍは少なくとも一種の遷移金属元素であり、Ｘは０≦Ｘ≦４、Ｙは０≦Ｙ≦１の範囲の数値である）で表されるシェブレル相化合物、活性炭、活性炭素繊維などである。バナジウム酸化物は、Ｖ２Ｏ５、Ｖ６Ｏ１３、Ｖ２Ｏ４、Ｖ３Ｏ８で示されるものである。
リチウム含有遷移金属酸化物は、リチウムと遷移金属との複合酸化物であり、リチウムと２種類以上の遷移金属を固溶したものであってもよい。複合酸化物は単独で使用しても、２種類以上を組合わせて使用してもよい。リチウム含有遷移金属酸化物は、具体的には、ＬｉＭ１ １−ｘ Ｍ２ ＸＯ２（式中Ｍ１、Ｍ２は少なくとも一種の遷移金属元素であり、Ｘは０≦Ｘ≦１の範囲の数値である）、またはＬｉＭ１ １−ＹＭ２ ＹＯ４（式中Ｍ１、Ｍ２は少なくとも一種の遷移金属元素であり、Ｙは０≦Ｙ≦１の範囲の数値である）で示される。
Ｍ１、Ｍ２で示される遷移金属元素は、Ｃｏ、Ｎｉ、Ｍｎ、Ｃｒ、Ｔｉ、Ｖ、Ｆｅ、Ｚｎ、Ａｌ、Ｉｎ、Ｓｎなどであり、好ましいのはＣｏ、Ｆｅ、Ｍｎ、Ｔｉ、Ｃｒ、Ｖ、Ａｌなどである。好ましい具体例は、ＬｉＣｏＯ２、ＬｉＮｉＯ２、ＬｉＭｎＯ２、ＬｉＮｉ０．９Ｃｏ０．１Ｏ２、ＬｉＮｉ０．５Ｃｏ０．５Ｏ２などである。
リチウム含有遷移金属酸化物は、例えば、リチウム、遷移金属の酸化物、水酸化物、塩類等を出発原料とし、これら出発原料を所望の金属酸化物の組成に応じて混合し、酸素雰囲気下６００〜１０００℃の温度で焼成することにより得ることができる。 [Positive electrode]
The positive electrode is formed, for example, by applying a positive electrode mixture comprising a positive electrode material, a binder and a conductive agent to the surface of the current collector. As the positive electrode material (positive electrode active material), a material capable of inserting / extracting a sufficient amount of lithium is preferably selected. Lithium-containing transition metal oxides, transition metal chalcogenides, lithium-containing compounds such as vanadium oxide and its lithium compounds, general formula M X Mo 6 OS 8-Y (wherein M is at least one transition metal element, X Is a value in the range of 0 ≦ X ≦ 4 and Y is a range of 0 ≦ Y ≦ 1), activated carbon, activated carbon fiber, and the like. Vanadium oxide is one represented by V 2 O 5, V 6 O 13, V 2 O 4, V 3 O 8.
The lithium-containing transition metal oxide is a composite oxide of lithium and a transition metal, and may be a solid solution of lithium and two or more transition metals. The composite oxide may be used alone or in combination of two or more. Specifically, the lithium-containing transition metal oxide is LiM 1 1-x M 2 X O 2 (wherein M 1 and M 2 are at least one transition metal element, and X is in a range of 0 ≦ X ≦ 1. LiM 1 1-Y M 2 Y O 4 (wherein M 1 and M 2 are at least one transition metal element, and Y is a value in the range of 0 ≦ Y ≦ 1). Indicated.
The transition metal elements represented by M 1 and M 2 are Co, Ni, Mn, Cr, Ti, V, Fe, Zn, Al, In, Sn, etc., preferably Co, Fe, Mn, Ti, Cr , V, Al, etc. Preferred examples include LiCoO 2 , LiNiO 2 , LiMnO 2 , LiNi 0.9 Co 0.1 O 2 , LiNi 0.5 Co 0.5 O 2 , and the like.
Examples of the lithium-containing transition metal oxide include lithium, transition metal oxides, hydroxides, salts, and the like as starting materials, and these starting materials are mixed in accordance with the composition of the desired metal oxide, and are mixed under an oxygen atmosphere. It can be obtained by firing at a temperature of ˜1000 ° C.

正極活物質は、前記化合物を単独で使用しても２種類以上併用してもよい。例えば、正極中に炭酸リチウム等の炭素塩を添加することができる。また、正極を形成するに際しては、従来公知の導電剤や結着剤などの各種添加剤を適宜に使用することができる。
正極は、前記正極材料、結合剤、および正極に導電性を付与するための導電剤よりなる正極合剤を、集電体の両面に塗布して正極合剤層を形成して作製される。結合剤としては、負極の作製に使用されるものと同じものが使用可能である。導電剤としては、黒鉛化物、カーボンブラックなど公知のものが使用される。
集電体の形状は特に限定されないが、箔状またはメッシュ、エキスパンドメタル等の網状等のものが用いられる。集電体の材質は、アルミニウム、ステンレス、ニッケル等である。その厚さは１０〜４０μｍのものが好適である。
正極も負極と同様に、正極合剤を溶剤中に分散させペースト状にし、このペースト状の正極合剤を集電体に塗布、乾燥して正極合剤層を形成してもよく、正極合剤層を形成した後、さらにプレス加圧等の圧着を行ってもよい。これにより正極合剤層が均一且つ強固に集電材に接着される。 The positive electrode active material may be used alone or in combination of two or more. For example, a carbon salt such as lithium carbonate can be added to the positive electrode. Moreover, when forming a positive electrode, conventionally well-known various additives, such as a electrically conductive agent and a binder, can be used suitably.
The positive electrode is produced by applying a positive electrode mixture comprising the positive electrode material, a binder, and a conductive agent for imparting conductivity to the positive electrode on both sides of the current collector to form a positive electrode mixture layer. As the binder, the same one as that used for producing the negative electrode can be used. As the conductive agent, known materials such as graphitized materials and carbon black are used.
The shape of the current collector is not particularly limited, but a foil shape or a mesh shape such as a mesh or expanded metal is used. The material of the current collector is aluminum, stainless steel, nickel or the like. The thickness is preferably 10 to 40 μm.
Similarly to the negative electrode, the positive electrode mixture may be formed in a paste by dispersing the positive electrode mixture in a solvent, and the paste-like positive electrode mixture may be applied to a current collector and dried to form a positive electrode mixture layer. After forming the agent layer, pressure bonding such as press pressing may be further performed. As a result, the positive electrode mixture layer is uniformly and firmly bonded to the current collector.

［非水電解質］
本発明のリチウムイオン二次電池に用いられる非水電解質としては、通常の非水電解液に使用される電解質塩である、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＡｓＦ６、ＬｉＣｌＯ４、ＬｉＢ（Ｃ６Ｈ５）、ＬｉＣｌ、ＬｉＢｒ、ＬｉＣＦ３ＳＯ３、ＬｉＣＨ３ＳＯ３、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＣ（ＣＦ３ＳＯ２）３、ＬｉＮ（ＣＦ３ＣＨ２ＯＳＯ２）２、ＬｉＮ（ＣＦ３ＣＦ２ＯＳＯ２）２、ＬｉＮ（ＨＣＦ２ＣＦ２ＣＨ２ＯＳＯ２）２、ＬｉＮ（（ＣＦ３）２ＣＨＯＳＯ２）２、ＬｉＢ［｛Ｃ６Ｈ３（ＣＦ３）２｝］４、ＬｉＡｌＣｌ４、ＬｉＳｉＦ６などのリチウム塩を用いることができる。酸化安定性の点からは、特に、ＬｉＰＦ６、ＬｉＢＦ４が好ましい。 [Nonaqueous electrolyte]
The non-aqueous electrolyte used in the lithium ion secondary battery of the present invention, an electrolyte salt used in the conventional non-aqueous electrolyte, LiPF 6, LiBF 4, LiAsF 6, LiClO 4, LiB (C 6 H 5 ), LiCl, LiBr, LiCF 3 SO 3 , LiCH 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiN (CF 3 CH 2 OSO 2 ) 2 , LiN (CF 3 CF 2 OSO 2) 2, LiN ( HCF 2 CF 2 CH 2 OSO 2) 2, LiN ((CF 3) 2 CHOSO 2) 2, LiB [{C 6 H 3 (CF 3) 2}] 4, LiAlCl 4, Lithium salts such as LiSiF 6 can be used. From the viewpoint of oxidation stability, LiPF 6 and LiBF 4 are particularly preferable.

電解液中の電解質塩濃度は０．１〜５ｍｏｌ／Ｌが好ましく、０．５〜３．０ｍｏｌ／Ｌがより好ましい。
非水電解質は液状の非水電解質としてもよく、固体電解質またはゲル電解質などの高分子電解質としてもよい。前者の場合、非水電解質電池は、いわゆるリチウムイオン二次電池として構成され、後者の場合は、非水電解質電池は高分子固体電解質、高分子ゲル電解質電池などの高分子電解質電池として構成される。 The electrolyte salt concentration in the electrolytic solution is preferably 0.1 to 5 mol / L, and more preferably 0.5 to 3.0 mol / L.
The non-aqueous electrolyte may be a liquid non-aqueous electrolyte or a polymer electrolyte such as a solid electrolyte or a gel electrolyte. In the former case, the non-aqueous electrolyte battery is configured as a so-called lithium ion secondary battery, and in the latter case, the non-aqueous electrolyte battery is configured as a polymer electrolyte battery such as a polymer solid electrolyte or a polymer gel electrolyte battery. .

非水電解質液を調製するための溶媒としては、エチレンカーボネート、プロピレンカーボネート、ジメチルカーボネート、ジエチルカーボネートなどのカーボネート、１，１−または１，２−ジメトキシエタン、１，２−ジエトキシエタン、テトラヒドロフラン、２−メチルテトラヒドロフラン、γ−ブチロラクトン、１，３−ジオキソラン、４−メチル−１，３−ジオキソラン、アニソール、ジエチルエーテルなどのエーテル、スルホラン、メチルスルホランなどのチオエーテル、アセトニトリル、クロロニトリル、プロピオニトリルなどのニトリル、ホウ酸トリメチル、ケイ酸テトラメチル、ニトロメタン、ジメチルホルムアミド、Ｎ−メチルピロリドン、酢酸エチル、トリメチルオルトホルメート、ニトロベンゼン、塩化ベンゾイル、臭化ベンゾイル、テトラヒドロチオフェン、ジメチルスルホキシド、３−メチル−２−オキサゾリドン、エチレングリコール、ジメチルサルファイトなどの非プロトン性有機溶媒などを用いることができる。   As a solvent for preparing the nonaqueous electrolyte solution, carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, and diethyl carbonate, 1,1- or 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, 1,3-dioxolane, 4-methyl-1,3-dioxolane, ethers such as anisole and diethyl ether, thioethers such as sulfolane and methylsulfolane, acetonitrile, chloronitrile, propionitrile, etc. Nitrile, trimethyl borate, tetramethyl silicate, nitromethane, dimethylformamide, N-methylpyrrolidone, ethyl acetate, trimethyl orthoformate, nitrobenzene, benzoyl chloride, Benzoyl, tetrahydrothiophene, dimethyl sulfoxide, 3-methyl-2-oxazolidone, ethylene glycol, aprotic organic solvents such as dimethyl sulfite may be used.

非水電解質を高分子固体電解質または高分子ゲル電解質などの高分子電解質とする場合には、マトリクスとして可塑剤（非水電解液）でゲル化された高分子を用いることが好ましい。前記マトリクスを構成する高分子としては、ポリエチレンオキサイドやその架橋体などのエーテル系高分子化合物、ポリメタクリレート系高分子化合物、ポリアクリレート系高分子化合物、ポリビニリデンフルオライドやビニリデンフルオライド−ヘキサフルオロプロピレン共重合体などのフッ素系高分子化合物などを用いることが特に好ましい。   When the non-aqueous electrolyte is a polymer electrolyte such as a polymer solid electrolyte or a polymer gel electrolyte, it is preferable to use a polymer gelled with a plasticizer (non-aqueous electrolyte) as a matrix. Examples of the polymer constituting the matrix include ether-based polymer compounds such as polyethylene oxide and cross-linked products thereof, polymethacrylate-based polymer compounds, polyacrylate-based polymer compounds, polyvinylidene fluoride, and vinylidene fluoride-hexafluoropropylene. It is particularly preferable to use a fluorine-based polymer compound such as a copolymer.

前記高分子固体電解質または高分子ゲル電解質には、可塑剤が配合されるが、該可塑剤としては、前記の電解質塩や非水溶媒が使用可能である。高分子ゲル電解質の場合、可塑剤である非水電解液中の電解質塩濃度は０．１〜５ｍｏｌ／Ｌが好ましく、０．５〜２．０ｍｏｌ／Ｌがより好ましい。
高分子固体電解質の作製方法は特に限定されないが、例えば、マトリクスを構成する高分子化合物、リチウム塩および非水溶媒（可塑剤）を混合し、加熱して高分子化合物を溶融する方法、有機溶剤に高分子化合物、リチウム塩、および非水溶媒（可塑剤）を溶解させた後、混合用有機溶剤を蒸発させる方法、重合性モノマー、リチウム塩および非水溶媒（可塑剤）を混合し、混合物に紫外線、電子線または分子線などを照射して、重合性モノマーを重合させ、ポリマーを得る方法などを挙げることができる。
ここで、前記固体電解質中の非水溶媒（可塑剤）の割合は１０〜９０質量％が好ましく、３０〜８０質量％がより好ましい。１０質量％未満であると導電率が低くなり、９０質量％を超えると機械的強度が弱くなり、成膜しにくくなる。 The polymer solid electrolyte or polymer gel electrolyte is mixed with a plasticizer, and as the plasticizer, the electrolyte salt and the non-aqueous solvent can be used. In the case of a polymer gel electrolyte, the concentration of the electrolyte salt in the nonaqueous electrolytic solution that is a plasticizer is preferably 0.1 to 5 mol / L, and more preferably 0.5 to 2.0 mol / L.
The method for producing the polymer solid electrolyte is not particularly limited. For example, a method of mixing a polymer compound constituting a matrix, a lithium salt, and a nonaqueous solvent (plasticizer) and heating to melt the polymer compound, an organic solvent A method in which a polymer compound, a lithium salt, and a non-aqueous solvent (plasticizer) are dissolved in, and an organic solvent for mixing is evaporated, a polymerizable monomer, a lithium salt, and a non-aqueous solvent (plasticizer) are mixed, and the mixture is mixed Examples thereof include a method of polymerizing a polymerizable monomer by irradiating an ultraviolet ray, an electron beam, a molecular beam or the like to obtain a polymer.
Here, the ratio of the non-aqueous solvent (plasticizer) in the solid electrolyte is preferably 10 to 90% by mass, and more preferably 30 to 80% by mass. If it is less than 10% by mass, the electrical conductivity will be low, and if it exceeds 90% by mass, the mechanical strength will be weak and film formation will be difficult.

［セパレータ］
本発明のリチウムイオン二次電池においては、セパレータを使用することもできる。
セパレータの材質は特に限定されるものではないが、例えば、織布、不織布、合成樹脂製微多孔膜などを用いることができる。前記セパレータの材質としては、合成樹脂製微多孔膜が好適であるが、なかでもポリオレフィン系微多孔膜が、厚さ、膜強度、膜抵抗の面で好適である。具体的には、ポリエチレンおよびポリプロピレン製微多孔膜、またはこれらを複合した微多孔膜等が好適である。 [Separator]
In the lithium ion secondary battery of the present invention, a separator can also be used.
Although the material of a separator is not specifically limited, For example, a woven fabric, a nonwoven fabric, a synthetic resin microporous film, etc. can be used. As a material for the separator, a microporous membrane made of synthetic resin is suitable. Among them, a polyolefin microporous membrane is suitable in terms of thickness, membrane strength, and membrane resistance. Specifically, polyethylene and polypropylene microporous membranes, or microporous membranes composed of these are suitable.

〔リチウムイオン二次電池〕
本発明のリチウムイオン二次電池は、上述した構成の負極、正極および非水電解質を、例えば、負極、非水電解質、正極の順で積層し、電池の外装材内に収容することで構成される。さらに、負極と正極の外側に非水電解質を配するようにしてもよい。
また、本発明のリチウムイオン二次電池の構造は特に限定されず、その形状、形態についても特に限定されるものではなく、用途、搭載機器、要求される充放電容量などに応じて、円筒型、角型、コイン型、ボタン型などの中から任意に選択することができる。より安全性の高い密閉型非水電解液電池を得るためには、過充電などの異常時に電池内圧上昇を感知して電流を遮断させる手段を備えたものを用いることが好ましい。
リチウムイオン二次電池が高分子固体電解質電池や高分子ゲル電解質電池の場合には、ラミネートフィルムに封入した構造とすることもできる。 [Lithium ion secondary battery]
The lithium ion secondary battery of the present invention is configured by laminating the negative electrode, the positive electrode, and the nonaqueous electrolyte having the above-described configuration in the order of, for example, the negative electrode, the nonaqueous electrolyte, and the positive electrode, and accommodating the laminate in the battery exterior material. The Further, a non-aqueous electrolyte may be disposed outside the negative electrode and the positive electrode.
In addition, the structure of the lithium ion secondary battery of the present invention is not particularly limited, and the shape and form thereof are not particularly limited, and are cylindrical, depending on the application, mounted equipment, required charge / discharge capacity, and the like. , Square shape, coin shape, button shape, and the like. In order to obtain a sealed nonaqueous electrolyte battery with higher safety, it is preferable to use a battery equipped with means for detecting an increase in the internal pressure of the battery and shutting off the current when an abnormality such as overcharging occurs.
In the case where the lithium ion secondary battery is a polymer solid electrolyte battery or a polymer gel electrolyte battery, a structure in which the lithium ion secondary battery is enclosed in a laminate film may be used.

次に本発明を実施例に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。また以下の実施例および比較例では、図４に示すように、少なくとも表面の一部に本発明の負極材料を有する負極合剤２が付着した集電体（負極）７ｂとリチウム箔よりなる対極（正極）４から構成される単極評価用のボタン型二次電池を作製して評価した。実電池は、本発明の概念に基づき、公知の方法に準じて作製することができる。   EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. In the following Examples and Comparative Examples, as shown in FIG. 4, a current collector (negative electrode) 7b having a negative electrode mixture 2 having the negative electrode material of the present invention attached to at least a part of its surface and a counter electrode comprising a lithium foil A button type secondary battery for single electrode evaluation composed of (positive electrode) 4 was prepared and evaluated. An actual battery can be produced according to a known method based on the concept of the present invention.

（実施例１）
［負極材料の作製］
平均粒子径５μｍ、平均偏平度２０の鱗片状黒鉛粒子と、平均粒径０．２μｍのシリコン粒子をポリアクリル酸水溶液に分散し、スプレードライ装置で噴霧乾燥処理し、球状の複合体前駆体を得た。次いでプラネタリミキサを用い、前記複合体前駆体にコールタールピッチのタール中油溶液を加えて混練したのち、窒素の不活性雰囲気中で、１０００℃で焼成処理することで目的の複合体である負極材料を得た。各素材の配合量は、最終製品である複合体におけるそれぞれの存在比率が表１に示す通りになるように調整した。噴霧乾燥は表２に示す条件で行った。レーザー式粒度分布計で測定した複合体の平均粒子径は１０μｍであった。複合体の平均アスペクト比は以降の実施例全てで、２以内であった。図１に示すＳＥＭ像から、鱗片状黒鉛粒子が表面では同心円状に配向して存在していることが分かった。図２に示す複合体断面の偏光顕微鏡像から、内部には空隙が存在し、また鱗片状黒鉛粒子が互いに非平行に存在していることが分かった。また図３に示すＥＤＸマッピング像から、シリコン粒子が分散して存在していることが分かった。 Example 1
[Production of negative electrode material]
A scaly graphite particle having an average particle diameter of 5 μm and an average flatness of 20 and silicon particles having an average particle diameter of 0.2 μm are dispersed in a polyacrylic acid aqueous solution and spray-dried by a spray drying apparatus to obtain a spherical composite precursor. Obtained. Next, a planetary mixer is used to add and knead the coal tar pitch oil-in-oil solution to the composite precursor, followed by firing at 1000 ° C. in an inert atmosphere of nitrogen to obtain the negative electrode material that is the target composite. Got. The blending amount of each material was adjusted so that the respective abundance ratios in the composite as the final product were as shown in Table 1. The spray drying was performed under the conditions shown in Table 2. The average particle size of the composite measured with a laser particle size distribution analyzer was 10 μm. The average aspect ratio of the composite was within 2 in all the following examples. From the SEM image shown in FIG. 1, it was found that the scaly graphite particles were present concentrically on the surface. From the polarizing microscope image of the composite cross section shown in FIG. 2, it was found that there were voids inside, and that the scaly graphite particles were non-parallel to each other. Moreover, it was found from the EDX mapping image shown in FIG. 3 that silicon particles exist in a dispersed state.

［負極合剤ペーストの作製］
次に、負極材料を用いて負極を作製した。まず、前記複合体からなる負極材料を９６質量部、結合剤としてのカルボキシメチルセルロース２質量部、およびスチレン−ブタジエンゴム２質量部を水に入れ、攪拌して負極合剤ペーストを調整した。 [Preparation of negative electrode mixture paste]
Next, a negative electrode was produced using the negative electrode material. First, 96 parts by mass of the negative electrode material composed of the composite, 2 parts by mass of carboxymethyl cellulose as a binder, and 2 parts by mass of styrene-butadiene rubber were placed in water and stirred to prepare a negative electrode mixture paste.

［作用電極（負極）の作製］
前記負極合剤ペーストを厚さ１５μｍの銅箔上に均一な厚さで塗布し、さらに真空中９０℃で分散媒の水を蒸発させて乾燥した。次いで、この銅箔上に塗布された負極合剤層をハンドプレスによって加圧した。さらに、銅箔と負極合剤層を直径１５．５ｍｍの円柱状に打抜いて、銅箔に密着した負極合剤層を有する作用電極（負極）を作製した。負極合剤層の密度は１．４ｇ／ｃｍ３であった。 [Production of working electrode (negative electrode)]
The negative electrode mixture paste was applied on a copper foil having a thickness of 15 μm to a uniform thickness, and further, water in a dispersion medium was evaporated at 90 ° C. in a vacuum to dry the paste. Next, the negative electrode mixture layer applied on the copper foil was pressed by a hand press. Further, the copper foil and the negative electrode mixture layer were punched into a columnar shape having a diameter of 15.5 mm to produce a working electrode (negative electrode) having a negative electrode mixture layer adhered to the copper foil. The density of the negative electrode mixture layer was 1.4 g / cm 3 .

［対極（正極）の作製］
次に、前記負極を用いて単極評価用のボタン型二次電池を作製した。正極にはニッケルネットからなる集電体と、該集電体に密着したリチウム金属箔からなる極板を用いた。 [Production of counter electrode (positive electrode)]
Next, a button type secondary battery for single electrode evaluation was produced using the negative electrode. As the positive electrode, a current collector made of nickel net and an electrode plate made of lithium metal foil in close contact with the current collector were used.

［電解液、セパレータ］
電解液は、エチレンカーボネート３３体積％とメチルエチルカーボネート６７体積％の混合溶剤に、ＬｉＰＦ６を１ｍｏｌ／Ｌとなる濃度で溶解させ、非水電解液を調製した。得られた非水電解液をセパレータとして厚さ２０μｍのポリプロピレン多孔質体に含浸させ、電解液が含浸したセパレータを作製した。なお、実電池については、本発明の概念に基づき、公知の方法に準じて作製することができる。 [Electrolyte, separator]
The electrolytic solution was prepared by dissolving LiPF 6 at a concentration of 1 mol / L in a mixed solvent of 33% by volume of ethylene carbonate and 67% by volume of methyl ethyl carbonate to prepare a nonaqueous electrolytic solution. The obtained nonaqueous electrolytic solution was impregnated into a 20 μm-thick polypropylene porous body as a separator to produce a separator impregnated with the electrolytic solution. In addition, about a real battery, it can produce according to a well-known method based on the concept of this invention.

［評価電池の構成］
図４に評価電池の構成としてボタン型二次電池を示す。
外装カップ１と外装缶３は、その周縁部において絶縁ガスケット６を介在させ、両周縁部をかしめて密閉した。その内部に外装缶３の内面から順に、ニッケルネットからなる集電体７ａ、リチウム箔よりなる円筒状の対極（正極）４、電解液が含浸されたセパレータ５、負極材料が付着した銅箔からなる集電体７ｂが積層された電池系である。
前記評価電池は電解液を含浸させたセパレータ５を集電体７ｂと負極合剤２からなる作用電極（負極）と、集電体７ａに密着した対極４との間に挟んで積層した後、集電体７ｂを外装カップ１内に、対極４を外装缶３内に収容して、外装カップ１と外装缶３とを合わせ、さらに、外装カップ１と外装缶３との周縁部に絶縁ガスケット６を介在させ、両周縁部をかしめて密閉して作製した。
以上により作製された評価電池について、２５℃の温度下で以下に示す充放電試験を行い、初期充放電効率、充電膨張率およびサイクル特性を計算した。結果を表１〜３に示した。 [Configuration of evaluation battery]
FIG. 4 shows a button type secondary battery as a configuration of the evaluation battery.
The exterior cup 1 and the exterior can 3 were sealed by interposing an insulating gasket 6 at the peripheral portion thereof and caulking both peripheral portions. From the inner surface of the outer can 3, a current collector 7 a made of nickel net, a cylindrical counter electrode (positive electrode) 4 made of lithium foil, a separator 5 impregnated with an electrolytic solution, and a copper foil to which a negative electrode material is attached A battery system in which current collectors 7b are stacked.
In the evaluation battery, the separator 5 impregnated with the electrolytic solution was sandwiched between the current collector 7b and the working electrode (negative electrode) made of the negative electrode mixture 2, and the counter electrode 4 in close contact with the current collector 7a. The current collector 7b is accommodated in the exterior cup 1, the counter electrode 4 is accommodated in the exterior can 3, the exterior cup 1 and the exterior can 3 are combined, and an insulating gasket is provided at the peripheral edge between the exterior cup 1 and the exterior can 3. 6 was interposed, and both peripheral portions were caulked and sealed.
About the evaluation battery produced by the above, the following charging / discharging test was done at the temperature of 25 degreeC, and the initial stage charging / discharging efficiency, the charge expansion coefficient, and the cycle characteristic were calculated. The results are shown in Tables 1-3.

［初期充放電効率］
回路電圧が０ｍＶに達するまで０．９ｍＡの定電流充電を行った後、回路電圧が０ｍＶに達した時点で定電圧充電に切替え、さらに電流値が２０μＡになるまで充電を続けた。その間の通電量から質量当たりの充電容量（単位：ｍＡｈ／ｇ）を求めた。その後、１２０分間休止した。次に０．９ｍＡの電流値で回路電圧が１．５Ｖに達するまで定電流放電を行い、この間の通電量から質量当たりの放電容量（単位：ｍＡｈ／ｇ）を求めた。下記式により初期充放電効率を計算した。
初期充放電効率（％）＝（放電容量／充電容量）×１００
なおこの試験では、リチウムイオンを負極材料に吸蔵する過程を充電、負極材料から離脱する過程を放電とした。 [Initial charge / discharge efficiency]
After constant current charging of 0.9 mA until the circuit voltage reached 0 mV, switching to constant voltage charging was performed when the circuit voltage reached 0 mV, and charging was continued until the current value reached 20 μA. The charging capacity per unit mass (unit: mAh / g) was determined from the amount of electricity applied during that time. Then, it rested for 120 minutes. Next, constant current discharge was performed until the circuit voltage reached 1.5 V at a current value of 0.9 mA, and the discharge capacity per unit mass (unit: mAh / g) was determined from the amount of electricity supplied during this period. The initial charge / discharge efficiency was calculated according to the following formula.
Initial charge / discharge efficiency (%) = (discharge capacity / charge capacity) × 100
In this test, the process of occluding lithium ions in the negative electrode material was charged, and the process of detaching from the negative electrode material was discharged.

［充電膨張率］
回路電圧が０ｍＶに達するまで０.９ｍＡの定電流充電を行った後、定電圧充電に切替え、電流値が２０μＡになるまで充電を続けた。充電状態で評価電池を解体し、負極をアルゴン雰囲気下でエチルメチルカーボネートにより洗浄し、マイクロメーターで厚みを測定した。充電前後の負極の厚みと銅箔の厚み（１５μｍ）から、次式により負極活物質の充電膨張率を計算した。
充電膨張率（％）＝（（充電後の負極の厚み−充電前の負極の厚み）／（充電前の負極の厚み−銅箔の厚み））×１００ [Charge expansion rate]
After constant current charging of 0.9 mA until the circuit voltage reached 0 mV, switching to constant voltage charging was continued until the current value reached 20 μA. The evaluation battery was disassembled in a charged state, the negative electrode was washed with ethyl methyl carbonate under an argon atmosphere, and the thickness was measured with a micrometer. From the thickness of the negative electrode before and after charging and the thickness of the copper foil (15 μm), the charge expansion coefficient of the negative electrode active material was calculated by the following formula.
Charge expansion coefficient (%) = ((Thickness of negative electrode after charging−Thickness of negative electrode before charging) / (Thickness of negative electrode before charging−Thickness of copper foil)) × 100

［サイクル特性］
質量当たりの放電容量、急速充電率、急速放電率を評価した評価電池とは別の評価電池を作製し、以下のような評価を行なった。
回路電圧が０ｍＶに達するまで４.０ｍＡの定電流充電を行った後、定電圧充電に切替え、電流値が２０μＡになるまで充電を続けた後、１２０分間休止した。次に４.０ｍＡの電流値で、回路電圧が１.５Ｖに達するまで定電流放電を行った。２０回充放電を繰返し、得られた質量当たりの放電容量から、次式を用いてサイクル特性を計算した。
サイクル特性（％）＝（第２０サイクルにおける放電容量／第１サイクルにおける放電容量）×１００ [Cycle characteristics]
An evaluation battery different from the evaluation battery that evaluated the discharge capacity per mass, the rapid charge rate, and the rapid discharge rate was produced and evaluated as follows.
After performing 4.0 mA constant current charging until the circuit voltage reached 0 mV, switching to constant voltage charging was continued until the current value reached 20 μA, and then rested for 120 minutes. Next, constant current discharge was performed at a current value of 4.0 mA until the circuit voltage reached 1.5V. The charge / discharge was repeated 20 times, and the cycle characteristics were calculated from the obtained discharge capacity per mass using the following formula.
Cycle characteristics (%) = (discharge capacity in 20th cycle / discharge capacity in 1st cycle) × 100

（実施例２）
複合体作製時の配合比を表１、２に示す通りにしたほかは、実施例１と同様にして複合体の作製、負極および評価電池の作製、ならびに電池特性評価を行った。
複合体のＳＥＭ像から、鱗片状黒鉛粒子が表面では同心円状に配向して存在し、複合体断面の偏光顕微鏡像から、内部には空隙が存在し、また鱗片状黒鉛粒子が互いに非平行に存在していることが分かった。またＥＤＸマッピング像から、シリコン粒子が分散して存在していることも分かった。 (Example 2)
Except that the compounding ratio at the time of producing the composite was as shown in Tables 1 and 2, the production of the composite, the production of the negative electrode and the evaluation battery, and the battery characteristics were evaluated in the same manner as in Example 1.
From the SEM image of the composite, the scaly graphite particles are concentrically oriented on the surface, and from the polarizing microscope image of the composite cross section, there are voids inside, and the scaly graphite particles are not parallel to each other. I found out that it exists. It was also found from the EDX mapping image that silicon particles were dispersed.

（実施例３，４）
表１に示した割合で、平均粒子径５μｍ、平均偏平度２０の鱗片状黒鉛粒子、平均粒径０．２μｍのシリコン粒子および黒鉛質繊維をポリアクリル酸水溶液に添加、混合した以外は、実施例１と同様にして複合体の作製、負極および評価電池の作製、ならびに電池特性評価を行った。
複合体のＳＥＭ像から、鱗片状黒鉛粒子が表面では同心円状に配向して存在し、複合体断面の偏光顕微鏡像から、内部には空隙が存在し、また鱗片状黒鉛粒子が互いに非平行に存在していることが分かった。またＥＤＸマッピング像から、シリコン粒子が分散して存在していることも分かった。複合体の外観および断面のＳＥＭ像から、複合体中に黒鉛質繊維が分散して存在していることも分かった。 (Examples 3 and 4)
Except for adding and mixing flaky graphite particles having an average particle diameter of 5 μm and an average flatness of 20 at a ratio shown in Table 1, silicon particles having an average particle diameter of 0.2 μm, and graphitic fibers into the polyacrylic acid aqueous solution. In the same manner as in Example 1, preparation of a composite, preparation of a negative electrode and an evaluation battery, and evaluation of battery characteristics were performed.
From the SEM image of the composite, the scaly graphite particles are concentrically oriented on the surface, and from the polarizing microscope image of the composite cross section, there are voids inside, and the scaly graphite particles are not parallel to each other. I found out that it exists. It was also found from the EDX mapping image that silicon particles were dispersed. From the appearance of the composite and the SEM image of the cross section, it was also found that the graphite fibers were dispersed in the composite.

（比較例１）
平均粒子径５μｍ、平均偏平度２０の鱗片状黒鉛粒子、平均粒径０．２μｍのシリコン粒子、およびコールタールピッチのタール中油溶液を二軸ニーダーで混練した。次いで混練品を金型成形し、その成形品を１０００℃で焼成処理したのち、平均粒子径が１０μｍとなるように粉砕して目的の負極材料を得た。これ以外は実施例１と同様に負極合剤の調製、負極および評価電池の作製、ならびに電池特性評価を行った。また、実施例１と同様に複合体の表面と断面を観察したところ、得られた複合体については、内部には空隙を有するものの、鱗片状黒鉛粒子が表面と内部のいずれでも非平行に存在しているのを確認した。 (Comparative Example 1)
A scaly graphite particle having an average particle size of 5 μm, an average flatness of 20, silicon particles having an average particle size of 0.2 μm, and a coal-tar pitch oil-in-tar solution were kneaded with a biaxial kneader. Next, the kneaded product was molded into a mold, and the molded product was fired at 1000 ° C. and then pulverized so as to have an average particle size of 10 μm to obtain a target negative electrode material. Except this, the preparation of the negative electrode mixture, the production of the negative electrode and the evaluation battery, and the battery characteristic evaluation were performed in the same manner as in Example 1. Further, when the surface and cross section of the composite were observed in the same manner as in Example 1, the obtained composite had voids inside, but the flaky graphite particles existed non-parallel both on the surface and inside. I confirmed that I was doing.

以上の評価結果を表１〜３に示した。実施例１〜４から、本発明の負極材料を用いたリチウムイオン二次電池は、黒鉛の理論容量を超える高い放電容量を有していることが分かる。また、実施例２〜４と比較例１の比較から、本発明の負極材料により、初期充放電効率、充電耐膨張率およびサイクル特性がより優れたものになることが分かる。   The above evaluation results are shown in Tables 1 to 3. From Examples 1 to 4, it can be seen that the lithium ion secondary battery using the negative electrode material of the present invention has a high discharge capacity exceeding the theoretical capacity of graphite. Further, from comparison between Examples 2 to 4 and Comparative Example 1, it can be seen that the negative electrode material of the present invention has better initial charge / discharge efficiency, charge expansion resistance, and cycle characteristics.

本発明は、リチウムイオン二次電池用負極材料として、充電時の金属質物の膨張を充分に緩和でき、黒鉛の理論容量を超える高い放電容量と、優れた初期充放電効率を示す負極材料を提供する。そのため、本発明の負極材料を用いるリチウムイオン二次電池は、近年の電池の高エネルギー密度化に対する要望を満たし、搭載する機器の小型化および高性能化に有用である。本発明の負極材料は、その特性を活かして、小型から大型までの高性能リチウムイオン二次電池に使用することができる。   As a negative electrode material for a lithium ion secondary battery, the present invention provides a negative electrode material that can sufficiently relieve the expansion of a metallic material during charging, exhibits a high discharge capacity exceeding the theoretical capacity of graphite, and excellent initial charge / discharge efficiency. To do. Therefore, the lithium ion secondary battery using the negative electrode material of the present invention satisfies the recent demand for higher energy density of the battery, and is useful for downsizing and higher performance of equipment to be mounted. The negative electrode material of the present invention can be used for high-performance lithium ion secondary batteries ranging from small to large, taking advantage of the characteristics.

１ 外装カップ
２ 負極合剤
３ 外装缶
４ 対極
５ セパレータ
６ 絶縁ガスケット
７ａ、７ｂ 集電体 DESCRIPTION OF SYMBOLS 1 Exterior cup 2 Negative electrode mixture 3 Exterior can 4 Counter electrode 5 Separator 6 Insulation gasket 7a, 7b Current collector

Claims (11)

鱗片状黒鉛粒子、焼成炭素およびリチウムと合金化可能な金属粒子からなる球状の複合体であって、前記複合体が内部に空隙を有し、かつ前記鱗片状黒鉛粒子が前記複合体の内部では、該内部に存在する鱗片状黒鉛粒子の総数の９０％以上が非平行に存在し、前記複合体の表面では同心円状に配向して存在し、
かつ、前記金属粒子が前記複合体粒子内部および／または表面に分散して存在するリチウムイオン二次電池用負極材料で、
前記負極材料の、水銀圧入法で測定した０．０１〜１００μｍの大きさの空隙の容積が、０．０５〜０．４ｃｍ ３ ／ｇであるリチウムイオン二次電池用負極材料。 A spherical composite composed of scaly graphite particles, metal particles that can be alloyed with calcined carbon and lithium, wherein the composite has voids inside, and the scaly graphite particles are inside the composite. 90% or more of the total number of scaly graphite particles present in the interior is present in a non-parallel manner, and is present in a concentric orientation on the surface of the composite,
And the negative electrode material for a lithium ion secondary battery in which the metal particles are present dispersed in and / or on the surface of the composite particles,
A negative electrode material for a lithium ion secondary battery, wherein the negative electrode material has a void volume of 0.01 to 100 μm as measured by a mercury intrusion method and having a volume of 0.05 to 0.4 cm 3 / g. 前記複合体を１００質量％として、
前記鱗片状黒鉛粒子：９８〜６０質量％、
前記焼成炭素：１〜２０質量％、および
前記金属粒子：１〜２０質量％である請求項１に記載のリチウムイオン二次電池用負極材料。 100% by mass of the complex,
The scaly graphite particles: 98-60% by mass,
2. The negative electrode material for a lithium ion secondary battery according to claim 1, wherein the calcined carbon is 1 to 20 mass%, and the metal particles are 1 to 20 mass%. 前記複合体に、さらに黒鉛質繊維を含む請求項１または２に記載のリチウムイオン二次電池用負極材料。 Wherein the composite negative electrode material for a lithium ion secondary battery according to claim 1 or 2 further comprising a graphite fiber. 前記複合体を１００質量％として、
前記鱗片状黒鉛粒子：９７．５〜５５質量％、
前記焼成炭素：１〜２０質量％、
前記金属粒子：１〜２０質量％、および
前記黒鉛質繊維：０．５〜５質量％である請求項３に記載のリチウムイオン二次電池用負極材料。 100% by mass of the complex,
The scaly graphite particles: 97.5 to 55% by mass,
The calcined carbon: 1 to 20% by mass,
The negative electrode material for a lithium ion secondary battery according to claim 3 , wherein the metal particles are 1 to 20% by mass, and the graphite fiber is 0.5 to 5% by mass. 前記鱗片状黒鉛粒子の平均偏平度（Ｌｙ／ｔ）が、０．５〜４０である請求項１ないし４のいずれか１項に記載のリチウムイオン二次電池用負極材料。 The negative electrode material for a lithium ion secondary battery according to any one of claims 1 to 4 , wherein an average flatness (Ly / t) of the scaly graphite particles is 0.5 to 40 . 請求項１ないし５のいずれか１項に記載のリチウムイオン二次電池用負極材料を含有するリチウムイオン二次電池用負極。 The negative electrode for lithium ion secondary batteries containing the negative electrode material for lithium ion secondary batteries of any one of Claim 1 thru | or 5 . 請求項６に記載のリチウムイオン二次電池用負極を有するリチウムイオン二次電池。 The lithium ion secondary battery which has a negative electrode for lithium ion secondary batteries of Claim 6 . 鱗片状黒鉛粒子、焼成炭素およびリチウムと合金化可能な金属粒子からなる球状の複合体の製造方法であって、前記鱗片状黒鉛粒子および前記金属粒子を炭素質材料および／または炭素質材料の前駆体である結着剤の溶液に固形分濃度５〜２５質量％で分散させ、噴霧乾燥処理した後、７００℃以上、１５００℃以下の温度範囲で熱処理を行い、前記した炭素質材料および炭素質材料の前駆体を焼成炭素とし、その後粉砕工程を経ずに最終製品とし、
前記最終製品が、鱗片状黒鉛粒子、焼成炭素およびリチウムと合金化可能な金属粒子からなる球状の複合体であって、前記複合体が内部に空隙を有し、かつ前記鱗片状黒鉛粒子が前記複合体の内部では非平行に存在し、前記複合体の表面では同心円状に配向して存在し、
かつ、前記金属粒子が前記複合体粒子内部および／または表面に分散して存在する、
リチウムイオン二次電池用負極材の製造方法。 A method for producing a spherical composite comprising scaly graphite particles, sintered carbon and metal particles that can be alloyed with lithium, wherein the scaly graphite particles and the metal particles are carbonaceous materials and / or precursors of carbonaceous materials. After being dispersed in a binder solution as a body at a solid content concentration of 5 to 25% by mass and spray-dried, heat treatment is performed in a temperature range of 700 ° C. or more and 1500 ° C. or less, and the above-described carbonaceous material and carbonaceous matter The precursor of the material is calcined carbon, and then the final product without going through the grinding process,
The final product is a spherical composite composed of scaly graphite particles, metal particles that can be alloyed with calcined carbon and lithium, the composite has voids inside, and the scaly graphite particles are It exists non-parallel inside the composite, and exists in a concentric orientation on the surface of the composite ,
And, wherein the metal particles that exist dispersed in the composite particles inside and / or surface,
A method for producing a negative electrode material for a lithium ion secondary battery. 鱗片状黒鉛粒子、焼成炭素、リチウムと合金化可能な金属粒子および黒鉛質繊維からなる球状の複合体の製造方法であって、前記鱗片状黒鉛粒子、前記金属粒子および黒鉛質繊維を炭素質材料および／または炭素質材料の前駆体である結着剤の溶液に固形分濃度５〜２５質量％で分散させ、噴霧乾燥処理した後、７００℃以上、１５００℃以下の温度範囲で熱処理を行い、前記した炭素質材料および炭素質材料の前駆体を焼成炭素とし、その後粉砕工程を経ずに最終製品とし、
前記最終製品が、鱗片状黒鉛粒子、焼成炭素およびリチウムと合金化可能な金属粒子からなる球状の複合体であって、前記複合体が内部に空隙を有し、かつ前記鱗片状黒鉛粒子が前記複合体の内部では非平行に存在し、前記複合体の表面では同心円状に配向して存在し、かつ、前記金属粒子が前記複合体粒子内部および／または表面に分散して存在する、
リチウムイオン二次電池用負極材の製造方法。 A method for producing a spherical composite comprising scaly graphite particles, calcined carbon, metal particles that can be alloyed with lithium, and graphite fibers, wherein the scaly graphite particles, the metal particles, and the graphite fibers are carbonaceous materials. And / or dispersed in a binder solution that is a precursor of a carbonaceous material at a solid content concentration of 5 to 25% by mass , spray-dried, and then heat-treated at a temperature range of 700 ° C. or higher and 1500 ° C. or lower, The carbonaceous material and the precursor of the carbonaceous material described above are calcined carbon, and then the final product without undergoing a pulverization step,
The final product is a spherical composite composed of scaly graphite particles, metal particles that can be alloyed with calcined carbon and lithium, the composite has voids inside, and the scaly graphite particles are inside the complex present in non-parallel, wherein the surface of the composite body exists oriented concentrically, and said metal particles that exist dispersed in the composite particles inside and / or surface,
A method for producing a negative electrode material for a lithium ion secondary battery. 前記噴霧乾燥処理品に、さらに炭素質材料および／または炭素質材料の前駆体を付着させた後、前記熱処理を行うことを特徴とする請求項８または９に記載のリチウムイオン二次電池用負極材の製造方法。 The negative electrode for a lithium ion secondary battery according to claim 8 or 9 , wherein a carbonaceous material and / or a precursor of the carbonaceous material is further attached to the spray-dried product, and then the heat treatment is performed. A method of manufacturing the material. 前記最終製品の、水銀圧入法で測定した０．０１〜１００μｍの大きさの空隙の容積が、０．０５〜０．４ｃｍ ３ ／ｇである請求項８ないし１０のいずれか１項に記載のリチウムイオン二次電池用負極材料の製造方法。 The final product, the void volume of the size of 0.01~100μm measured by mercury porosimetry, according to any one of claims 8 are 0.05~0.4cm 3 / g 10 A method for producing a negative electrode material for a lithium ion secondary battery.
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