JP2016157631A - Negative electrode active material, and lithium secondary battery arranged by use thereof - Google Patents

Negative electrode active material, and lithium secondary battery arranged by use thereof Download PDF

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JP2016157631A
JP2016157631A JP2015035421A JP2015035421A JP2016157631A JP 2016157631 A JP2016157631 A JP 2016157631A JP 2015035421 A JP2015035421 A JP 2015035421A JP 2015035421 A JP2015035421 A JP 2015035421A JP 2016157631 A JP2016157631 A JP 2016157631A
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negative electrode
active material
electrode active
mass
phosphate
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芳浩 新海
Yoshihiro Shinkai
芳浩 新海
上野　哲也
Tetsuya Ueno
哲也 上野
芳輝 河野
Yoshiteru Kono
芳輝 河野
謙二 荻須
Kenji Ogisu
謙二 荻須
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TDK Corp
Toda Kogyo Corp
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Toda Kogyo Corp
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Abstract

PROBLEM TO BE SOLVED: To provide a negative electrode active material which enables the reduction in capacity degradation owing to a charge and discharge cycle of a lithium secondary battery.SOLUTION: A negative electrode active material comprises: negative electrode active material particles including Si as its primary component; and a phosphate deposited on the surface of each negative electrode active material particle. The phosphate is expressed by AlTiPO(where 0<x<1, and 0.75<y<1), in which to the total mass of Al, Ti and P, Al is 6.1-8.3 mass%, Ti is 54.6-61.7 mass%, and P is 32.1-38.6 mass%. The phosphate is included by 4.7-26.9 mass% to Si in the negative electrode active material particles.SELECTED DRAWING: Figure 1

Description

本発明は、負極活物質、及びそれを用いたリチウム二次電池に関する。   The present invention relates to a negative electrode active material and a lithium secondary battery using the same.

リチウムイオン二次電池は、パソコンや携帯機器に使用されており、使用機器の小型化や多機能化に伴って高容量化が要求されている。しかし、現在のリチウムイオン二次電池に使用されている負極活物質は、人造黒鉛や天然黒鉛などの炭素系材料であり、理論容量が３７２ｍＡｈ／ｇであって、これ以上の容量増大は望めない。   Lithium ion secondary batteries are used in personal computers and portable devices, and higher capacities are required as the devices used become smaller and multifunctional. However, the negative electrode active material used in the present lithium ion secondary battery is a carbon-based material such as artificial graphite or natural graphite, and has a theoretical capacity of 372 mAh / g, and a further increase in capacity cannot be expected. .

そのため、理論容量がより大きいシリコン（Ｓｉ）や錫（Ｓｎ）等の金属材料やその酸化物材料を用いた負極が提案され、特に高比容量が得られるＳｉが注目されている。これらの材料は、初期の数サイクル程度は非常に高い容量を示すが、充放電を繰り返すことによって活物質の膨張収縮による微粉化が生じ、負極活物質が集電体から脱落するため、次第に充放電容量が低下して電池の寿命となるサイクル特性が劣るという問題があった。   Therefore, a negative electrode using a metal material such as silicon (Si) or tin (Sn) having a larger theoretical capacity, or an oxide material thereof has been proposed, and Si that can obtain a high specific capacity has attracted attention. These materials have a very high capacity in the initial few cycles, but due to repeated charge and discharge, pulverization occurs due to expansion and contraction of the active material, and the negative electrode active material falls off from the current collector. There has been a problem in that the cycle characteristics that reduce the discharge capacity and the life of the battery are poor.

上記の問題を解決するため、特許文献１では、金属または半金属、とくにＳｉを炭素で被覆することで、リチウム吸蔵時（充電時）の膨張を抑制し、充放電サイクルに優れたリチウム二次電池用負極材料を提案している。また、特許文献２では、ＳｉまたはＳｎを金属酸化物または半金属酸化物で複合化することにより、充電時のリチウム（Ｌｉ）の不均一な析出・拡散による不均一な膨張・崩壊を抑制する粉末材料を提案している。   In order to solve the above-mentioned problem, Patent Document 1 discloses a lithium secondary that is excellent in charge / discharge cycle by suppressing expansion during lithium occlusion (during charging) by coating metal or metalloid, particularly Si, with carbon. A battery negative electrode material has been proposed. Further, in Patent Document 2, by combining Si or Sn with a metal oxide or a semi-metal oxide, uneven expansion / collapse due to uneven precipitation / diffusion of lithium (Li) during charging is suppressed. A powder material is proposed.

特許第４３９３６１０号Japanese Patent No. 4393610 特開２００８−１６４４６公報JP 2008-16446 A

特許文献１ではＳｉを使用しているにも関わらず１０００ｍＡｈ／ｇ以上の容量をもつ負極活物質には至っていない。また、特許文献２に記載の手法により得られる負極活物質を用いて電極を作製し、Ｌｉ対極のハーフセルで評価を作製したところ、サイクル試験による容量劣化が大きいという問題があった。   In Patent Document 1, although Si is used, no negative electrode active material having a capacity of 1000 mAh / g or more has been reached. Moreover, when an electrode was prepared using a negative electrode active material obtained by the method described in Patent Document 2 and evaluation was performed using a Li counter electrode half-cell, there was a problem that capacity degradation due to a cycle test was large.

本発明は上記課題に鑑みて為されたものであり、その目的は、リチウム二次電池の高容量化且つ充放電サイクルによる容量劣化を低減する負極活物質及びリチウム二次電池を提供することにある。   The present invention has been made in view of the above problems, and an object of the present invention is to provide a negative electrode active material and a lithium secondary battery that increase the capacity of the lithium secondary battery and reduce capacity deterioration due to charge / discharge cycles. is there.

上記課題を解決するために、本発明者らは、鋭意研究を重ねた結果、Ｓｉを主成分とする負極活物質粒子において、その表面に付着するリン酸塩とサイクル試験での容量維持率に相関関係があることを見出し、本発明を完成するに至った。   In order to solve the above-mentioned problems, the present inventors have conducted extensive research, and as a result, in the negative electrode active material particles containing Si as a main component, the phosphate adhering to the surface and the capacity retention rate in the cycle test The present inventors have found that there is a correlation and have completed the present invention.

すなわち、本発明の負極活物質は、Ｓｉを主成分とする負極活物質粒子と、その表面に付着するリン酸塩と、を含有し、前記リン酸塩は、ＡｌｘＴｉｙ（１−ｘ）ＰＯ４（０＜ｘ＜１、０．７５＜ｙ＜１）で表される化合物であると共に、ＡｌとＴｉとＰの合計質量に対してＡｌが６．１ｍａｓｓ％以上８．３ｍａｓｓ％以下、Ｔｉが５４．６ｍａｓｓ％以上６１．７ｍａｓｓ％以下、Ｐが３２．１ｍａｓｓ％以上３８．６ｍａｓｓ％以下、であり、前記リン酸塩は、前記負極活物質粒子中のＳｉに対して、４．７ｍａｓｓ％以上２６．９ｍａｓｓ％以下で含有されていることを特徴とする。 That is, the negative electrode active material of the present invention contains negative electrode active material particles mainly composed of Si and a phosphate adhering to the surface thereof, and the phosphate contains Al x Ti y (1-x ) PO 4 (0 <x <1, 0.75 <y <1) and Al is 6.1 mass% or more and 8.3 mass% or less with respect to the total mass of Al, Ti, and P Ti is 54.6 mass% or more and 61.7 mass% or less, P is 32.1 mass% or more and 38.6 mass% or less, and the phosphate is based on Si in the negative electrode active material particles. It is contained in 7 mass% or more and 26.9 mass% or less.

本発明者らが、この上記のように構成された負極活物質を用いて作製したリチウム対極のハーフセルのサイクル試験を実施したところ、従来に比して、容量維持率が格別に大きいことが判明した。かかる効果が奏される作用機構の詳細は、未だ明らかではないものの、例えば、以下のとおり推定される。    When the present inventors conducted a cycle test of a lithium counter electrode half-cell manufactured using the negative electrode active material configured as described above, it was found that the capacity retention rate was remarkably higher than before. did. The details of the mechanism of action that produces this effect are not yet clear, but are estimated as follows, for example.

本発明にかかる負極活物質によれば、ＡｌｘＴｉｙ（１−ｘ）ＰＯ４が、Ｓｉ表面に存在することで、Ｓｉの膨張収縮による応力を緩和し、容量劣化を低減することができる。なお、ＡｌｘＴｉ１−ｘＰＯ４が４．７ｍａｓｓ％未満では、量が不十分となり効果となる容量が減少する可能性があり、２７．０ｍａｓｓ％以上では容量が減少する可能性がある。 According to the negative electrode active material according to the present invention, Al x Ti y (1-x) PO 4 is present on the Si surface, so that stress due to expansion and contraction of Si can be relieved and capacity degradation can be reduced. . If Al x Ti 1-x PO 4 is less than 4.7 mass%, the amount is insufficient and the effective capacity may be reduced, and if it is 27.0 mass% or more, the capacity may be reduced.

また、本発明にかかる負極活物質は、Ｓｉを主成分とする負極活物質粒子は二次粒子を構成し、その二次粒子の表面に前記リン酸塩が被覆されていることが好ましい。このような構成によれば、充放電による負極活物質の膨張による二次粒子の崩壊をより抑制することができるため容量劣化が少なくなる。但し、作用はこれらに限定されない。   In the negative electrode active material according to the present invention, it is preferable that the negative electrode active material particles containing Si as a main component constitute secondary particles, and the surface of the secondary particles is coated with the phosphate. According to such a configuration, the degradation of the secondary particles due to the expansion of the negative electrode active material due to charge / discharge can be further suppressed, so that the capacity deterioration is reduced. However, the action is not limited to these.

ここで、本明細書において、「一次粒子」とは、粉末に含まれる最小単位となる粒子を意味し、一方、かかる一次粒子が分子間力等によって凝集、あるいは緩やかなネッキングによって連結して形成される粒子を「二次粒子」と表記する。  Here, in this specification, the “primary particles” mean particles that are the smallest unit contained in the powder, and on the other hand, the primary particles are formed by agglomeration due to intermolecular force or the like or connected by loose necking. The resulting particles are referred to as “secondary particles”.

また、本発明にかかる負極活物質は、前記リン酸塩の平均一次粒子径を前記二次粒子の平均二次粒子径で除した値が、０．２０以上０．４８以下であることが好ましい。
このような構成によれば、充放電による負極活物質の膨張による二次粒子の崩壊をより抑制することができるため容量劣化が少なくなる。
なお、０．２０未満であるとＳｉ一次粒子同士の接合が不十分でＳｉ二次粒子の崩壊を抑制効果が小さくなる傾向にある。０．４９以上であるとＳｉ粒子に対して、リン酸塩の一次粒子の粒径が大きくなり、Ｓｉ二次粒子に付着せず独立して存在する粒子が増えることで、Ｓｉ二次粒子の崩壊を抑制に寄与するリン酸塩が減少し、容量維持率が低下する傾向にある。また、リン酸塩の質量比が大きくなるため、容量も減少する。 In the negative electrode active material according to the present invention, a value obtained by dividing the average primary particle diameter of the phosphate by the average secondary particle diameter of the secondary particles is preferably 0.20 or more and 0.48 or less. .
According to such a configuration, the degradation of the secondary particles due to the expansion of the negative electrode active material due to charge / discharge can be further suppressed, so that the capacity deterioration is reduced.
In addition, when it is less than 0.20, the bonding between the Si primary particles is insufficient, and the effect of suppressing the collapse of the Si secondary particles tends to be small. When the particle size is 0.49 or more, the particle size of the primary particles of the phosphate is larger than that of the Si particles. There is a tendency that the phosphate that contributes to the suppression of collapse decreases and the capacity retention rate decreases. Moreover, since the mass ratio of phosphate increases, the capacity also decreases.

ここで、「平均一次粒子径」とは、無作為に選択した１０個の一次粒子について、平均して算出したものを平均一次粒子径とし、「平均二次粒子径」とは、無作為に選択した１０個の二次粒子について、平均して算出したものを平均二次粒子径とする。粒子径とは、粒子のヘイウッド径を測定したものであり、例えば、粒子のＴＥＭ−ＥＤＳ観察等による、Ｓｉ粒子についてはＳｉのマッピング、ＡｌｘＴｉｙ（１−ｘ）ＰＯ４についてはＡｌ，Ｔｉ，Ｐのマッピングにより、測定可能である。 Here, the “average primary particle size” is the average primary particle size calculated from the average of 10 randomly selected primary particles, and the “average secondary particle size” is randomly selected. The average secondary particle diameter is determined by averaging the 10 selected secondary particles. The particle diameter is a value obtained by measuring the Haywood diameter of the particle. For example, by TEM-EDS observation of the particle, Si mapping for the Si particle, Al x Ti y (1-x) PO 4 for Al, Measurement is possible by mapping Ti and P.

本発明にかかる負極活物質を用いた負極と、電解質と正極とを具備したリチウム二次電池として用いることができる。    The present invention can be used as a lithium secondary battery including a negative electrode using the negative electrode active material according to the present invention, an electrolyte, and a positive electrode.

本発明によれば、リチウム二次電池において高容量化且つ充放電サイクルによる容量劣化を低減できる負極活物質及びそれを用いたリチウム二次電池が提供できる。    ADVANTAGE OF THE INVENTION According to this invention, the negative electrode active material which can raise the capacity | capacitance in a lithium secondary battery, and can reduce the capacity deterioration by a charging / discharging cycle, and a lithium secondary battery using the same can be provided.

本実施形態のＳｉを主成分とする負極活物質粒子の二次粒子及び一次粒子、並びにリン酸塩の一次粒子の凝集状態を概念的に示す模式図である。It is a schematic diagram which shows notionally the aggregation state of the secondary particle and primary particle of the negative electrode active material particle which have Si as a main component of this embodiment, and the primary particle of phosphate. 本実施形態に係るリチウムイオン二次電池の模式断面図である。It is a schematic cross section of the lithium ion secondary battery according to the present embodiment.

以下、本発明の実施の形態について説明する。なお、以下の実施の形態は、本発明を説明するための例示であり、本発明はその実施の形態のみに限定されるものではない。なお、図面中、同一要素には同一符号を付し、重複する説明は省略する。また、上下左右等の位置関係は、特に断らない限り、図面に示す位置関係に基づくものとする。更に、図面の寸法比率は図示の比率に限られるものではない。   Embodiments of the present invention will be described below. In addition, the following embodiment is an illustration for demonstrating this invention, and this invention is not limited only to the embodiment. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

図１は、本実施形態の負極活物質として、のＳｉを主成分とする負極活物質粒子の二次粒子及び一次粒子の凝集状態、並びにリン酸塩の一次粒子を概念的に示す模式図である。
負極活物質９は、Ｓｉを主成分とする負極活物質粒子１とリン酸塩３から構成されており、Ｓｉを主成分とする負極活物質粒子の一次粒子径は、０．０１〜１μｍ、好ましくは０．０１〜０．５μｍ、より好ましくは０．０１〜０．２μｍがよい。また、その一次粒子１が凝集または連結することにより形成された平均二次粒子径は、０．３〜１５μｍ、好ましくは０．３〜１０μｍ、より好ましくは０．３〜５μｍが好ましい。
一方、リン酸塩の一次粒子３は、０．０６〜５μｍ、好ましくは０．０６〜３μｍ、より好ましくは０．０６〜１μｍがよい。
また、負極活物質粒子の二次粒子２は、図示の如く、複数の一次粒子が凝集または連結することにより、海綿状の構造を有するものとなっていることが好ましい。 FIG. 1 is a schematic diagram conceptually showing the secondary particles and the primary particle aggregation state of negative electrode active material particles mainly composed of Si as the negative electrode active material of the present embodiment, and primary particles of phosphate. is there.
The negative electrode active material 9 is composed of negative electrode active material particles 1 mainly composed of Si and phosphate 3, and the primary particle diameter of the negative electrode active material particles mainly composed of Si is 0.01 to 1 μm, Preferably it is 0.01-0.5 micrometer, More preferably, 0.01-0.2 micrometer is good. Moreover, the average secondary particle diameter formed by aggregation or connection of the primary particles 1 is 0.3 to 15 μm, preferably 0.3 to 10 μm, more preferably 0.3 to 5 μm.
On the other hand, the primary particle 3 of phosphate is 0.06 to 5 μm, preferably 0.06 to 3 μm, more preferably 0.06 to 1 μm.
Moreover, it is preferable that the secondary particles 2 of the negative electrode active material particles have a sponge-like structure by aggregating or connecting a plurality of primary particles as illustrated.

負極活物質９の原料となるＳｉを主成分とする負極活物質粒子は、公知の材料を用いることができる。例えば、物理粉砕Ｓｉや高周波熱プラズマによるＳｉ、四塩化ケイ素の還元によるＳｉ、一部が酸化物で構成されているＳｉ−Ｏ系材料が挙げられるが、これらに限定されない。また、樹脂による結着や凝集により二次粒子となっていることが好ましい。    A known material can be used for the negative electrode active material particles containing Si as a main component as the raw material of the negative electrode active material 9. For example, physical pulverized Si, Si by high-frequency thermal plasma, Si by reduction of silicon tetrachloride, and Si—O-based materials partially composed of oxides are exemplified, but are not limited thereto. Moreover, it is preferable that it becomes a secondary particle by the binding and aggregation by resin.

リン酸塩３の原料となるアルミニウム，チタン，リン化合物は、ＡｌｘＴｉ１−ｘＰＯ４を生成するものであれば特に限定されないが、アルミニウム化合物としては、硝酸アルミニウム、酢酸アルミニウム、硫酸アルミニウム、炭酸アルミニウム、塩化アルミニウム、チタン化合物としては、塩化チタン、チタンアルコキシド、リン化合物としては、リン酸アンモニウム、リン酸一アンモニウム、リン酸二アンモニウム、リン酸、が挙げられる。 The aluminum, titanium, and phosphorus compound used as the raw material of the phosphate 3 are not particularly limited as long as they produce Al x Ti 1-x PO 4 , but examples of the aluminum compound include aluminum nitrate, aluminum acetate, aluminum sulfate, Examples of the aluminum carbonate, aluminum chloride, and titanium compound include titanium chloride, titanium alkoxide, and the phosphorus compound, such as ammonium phosphate, monoammonium phosphate, diammonium phosphate, and phosphoric acid.

Ｓｉを主成分とする負極活物質粒子の二次粒子２には、リン酸塩の前駆体を付着させて焼成することでリン酸塩の一次粒子３を付着させることが好ましい。また、リン酸塩の前駆体を付着させる方法としては、Ｓｉの二次粒子２とリン酸塩の前駆体を溶液中に分散させ、乾燥させる方法が好ましい。乾燥方法としては、ＣＤドライやスプレードライが挙げられるが、これらに限定されない。  It is preferable that the primary particles 3 of the phosphate are adhered to the secondary particles 2 of the negative electrode active material particles containing Si as a main component by attaching a precursor of the phosphate and firing. Further, as a method for attaching the phosphate precursor, a method in which the Si secondary particles 2 and the phosphate precursor are dispersed in a solution and dried is preferable. Examples of the drying method include, but are not limited to, CD drying and spray drying.

上述のように説明した負極活物質を用い負極とし、さらに正極と電解質を含浸させたセパレータを用いてリチウムイオン二次電池とすることができる。  A negative electrode using the negative electrode active material described above can be used as a negative electrode, and a lithium ion secondary battery can be formed using a separator impregnated with a positive electrode and an electrolyte.

（リチウムイオン二次電池）
図２に示すように、本実施形態に係るリチウムイオン二次電池１００は、互いに対向する板状の負極２０及び板状の正極１０と、負極２０と正極１０との間に隣接して配置される板状のセパレータ１８と、を備える発電要素３０と、リチウムイオンを含む電解質と、これらを密閉した状態で収容するケース５０と、負極２０に一方の端部が電気的に接続されると共に他方の端部がケースの外部に突出される負極リード６２と、正極１０に一方の端部が電気的に接続されると共に他方の端部がケースの外部に突出される正極リード６０とを備える。 (Lithium ion secondary battery)
As shown in FIG. 2, the lithium ion secondary battery 100 according to the present embodiment is disposed adjacent to each other between the plate-like negative electrode 20 and the plate-like positive electrode 10 facing each other, and the negative electrode 20 and the positive electrode 10. A plate-shaped separator 18, an electrolyte containing lithium ions, a case 50 for containing these in a sealed state, and one end electrically connected to the negative electrode 20 and the other The negative electrode lead 62 whose one end protrudes outside the case, and the positive electrode lead 60 whose one end is electrically connected to the positive electrode 10 and whose other end protrudes outside the case.

負極２０は、負極集電体２２と、負極集電体２２上に形成された負極活物質層２４と、を有する。また、正極１０は、正極集電体１２と、正極集電体１２上に形成された正極活物質層１４と、を有する。セパレータ１８は、負極活物質層２４と正極活物質層１４との間に位置している。  The negative electrode 20 includes a negative electrode current collector 22 and a negative electrode active material layer 24 formed on the negative electrode current collector 22. The positive electrode 10 includes a positive electrode current collector 12 and a positive electrode active material layer 14 formed on the positive electrode current collector 12. The separator 18 is located between the negative electrode active material layer 24 and the positive electrode active material layer 14.

負極活物質層２４は、上述した本実施形態にかかる上記負極活物質を含有し、その他、負極バインダー、及び、必要に応じた量の導電助剤から主に構成されるものである。  The negative electrode active material layer 24 contains the above-described negative electrode active material according to the present embodiment, and is mainly composed of a negative electrode binder and a conductive auxiliary agent in an amount as necessary.

（負極集電体）
負極集電体２２は、導電性の板材であればよく、例えば、銅、ニッケル、ステンレス又はそれらの合金の金属薄板（金属箔）を用いることができる。 (Negative electrode current collector)
The negative electrode current collector 22 may be any conductive plate material, and for example, a metal thin plate (metal foil) of copper, nickel, stainless steel, or an alloy thereof can be used.

（負極活物質層）
負極活物質層２４は、負極活物質、バインダー、及び、必要に応じた量の導電助剤から主に構成されるものである。 (Negative electrode active material layer)
The negative electrode active material layer 24 is mainly composed of a negative electrode active material, a binder, and a conductive auxiliary agent in an amount as required.

（負極バインダー）
バインダーは、負極活物質同士を結合すると共に、負極活物質と集電体２２とを結合している。バインダーは、上述の結合が可能なものであればよく、例えば、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリテトラフルオロエチレン（ＰＴＦＥ）等のフッ素樹脂が挙げられる。更に、上記の他に、バインダーとして、例えば、セルロース、スチレン・ブタジエンゴム、エチレン・プロピレンゴム、ポリイミド樹脂、ポリアミドイミド樹脂、アクリル樹脂等を用いてもよい。また、バインダーとして電子伝導性の導電性高分子やイオン伝導性の導電性高分子を用いてもよい。電子伝導性の導電性高分子としては、例えば、ポリアセチレン等が挙げられる。この場合は、バインダーが導電助剤粒子の機能も発揮するので導電助剤を添加しなくてもよい。イオン伝導性の導電性高分子としては、例えば、リチウムイオン等のイオンの伝導性を有するものを使用することができ、例えば、高分子化合物（ポリエチレンオキシド、ポリプロピレンオキシド等のポリエーテル系高分子化合物、ポリフォスファゼン等）のモノマーと、ＬｉＣｌＯ４、ＬｉＢＦ４、ＬｉＰＦ６等のリチウム塩又はリチウムを主体とするアルカリ金属塩と、を複合化させたもの等が挙げられる。複合化に使用する重合開始剤としては、例えば、上記のモノマーに適合する光重合開始剤または熱重合開始剤が挙げられる。 (Negative electrode binder)
The binder binds the negative electrode active materials to the current collector 22 while bonding the negative electrode active materials to each other. The binder is not particularly limited as long as the above-described bonding is possible, and examples thereof include fluorine resins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE). In addition to the above, for example, cellulose, styrene / butadiene rubber, ethylene / propylene rubber, polyimide resin, polyamideimide resin, acrylic resin, or the like may be used as the binder. Alternatively, an electron conductive conductive polymer or an ion conductive conductive polymer may be used as the binder. Examples of the electron conductive conductive polymer include polyacetylene. In this case, since the binder also exhibits the function of the conductive assistant particles, it is not necessary to add the conductive assistant. As the ion-conductive conductive polymer, for example, those having ion conductivity such as lithium ion can be used. For example, polymer compounds (polyether-based polymer compounds such as polyethylene oxide and polypropylene oxide) , Polyphosphazene, etc.) and a lithium salt such as LiClO 4 , LiBF 4 , LiPF 6 , or an alkali metal salt mainly composed of lithium, and the like. Examples of the polymerization initiator used for the combination include a photopolymerization initiator or a thermal polymerization initiator that is compatible with the above-described monomer.

負極活物質層２４中のバインダーの含有量は特に限定されないが、負極活物質、導電助剤及びバインダーの質量の和を基準にして、２〜３０質量％であることが好ましい。負極活物質とバインダーの含有量を上記範囲とすることにより、得られた負極活物質層２４において、バインダーの量が少なすぎて強固な負極活物質層を形成できなくなる傾向を抑制できる。また、電気容量に寄与しないバインダーの量が多くなり、十分な体積エネルギー密度を得ることが困難となる傾向も抑制できる。   Although content of the binder in the negative electrode active material layer 24 is not specifically limited, It is preferable that it is 2-30 mass% on the basis of the sum of the mass of a negative electrode active material, a conductive support agent, and a binder. By setting the content of the negative electrode active material and the binder in the above range, in the obtained negative electrode active material layer 24, the tendency that the amount of the binder is too small to form a strong negative electrode active material layer can be suppressed. In addition, the amount of the binder that does not contribute to the electric capacity increases, and the tendency that it is difficult to obtain a sufficient volume energy density can be suppressed.

（負極導電助剤）
導電助剤も、負極活物質層２４の導電性を良好にするものであれば特に限定されず、公知の導電助剤を使用できる。例えば、黒鉛、カーボンブラック等の炭素系材料や、銅、ニッケル、ステンレス、鉄等の金属微粉、炭素材料及び金属微粉の混合物、ＩＴＯ等の導電性酸化物が挙げられる。 (Negative conductive auxiliary)
The conductive auxiliary agent is not particularly limited as long as it improves the conductivity of the negative electrode active material layer 24, and a known conductive auxiliary agent can be used. Examples thereof include carbon-based materials such as graphite and carbon black, metal fine powders such as copper, nickel, stainless steel, and iron, a mixture of carbon materials and metal fine powders, and conductive oxides such as ITO.

負極活物質層２４中の導電助剤の含有量も特に限定されないが、添加する場合には負極活物質の質量に対して１〜５０質量％であることが好ましい。   The content of the conductive additive in the negative electrode active material layer 24 is not particularly limited, but when added, it is preferably 1 to 50% by mass with respect to the mass of the negative electrode active material.

（正極集電体）
正極集電体１２は、導電性の板材であればよく、例えば、アルミニウム又はそれらの合金、ステンレス等の金属薄板（金属箔）を用いることができる。 (Positive electrode current collector)
The positive electrode current collector 12 may be a conductive plate material, and for example, a metal thin plate (metal foil) such as aluminum, an alloy thereof, or stainless steel can be used.

（正極活物質層）
正極活物質層１４は、正極活物質、バインダー、及び、必要に応じた量の導電助剤から主に構成されるものである。 (Positive electrode active material layer)
The positive electrode active material layer 14 is mainly composed of a positive electrode active material, a binder, and a conductive auxiliary agent in an amount as necessary.

（正極活物質）
正極活物質としては、リチウムイオンの吸蔵及び放出、リチウムイオンの脱離及び挿入（インターカレーション）、又は、リチウムイオンと該リチウムイオンのカウンターアニオン（例えば、ＰＦ６ −）とのドープ及び脱ドープを可逆的に進行させることが可能であれば特に限定されず、公知の電極活物質を使用できる。例えば、コバルト酸リチウム（ＬｉＣｏＯ２）、ニッケル酸リチウム（ＬｉＮｉＯ２）、リチウムマンガンスピネル（ＬｉＭｎ２Ｏ４）、及び、一般式：ＬｉＮｉｘＣｏｙＭｎｚＭａＯ２（ｘ＋ｙ＋ｚ＋ａ＝１、０≦ｘ≦１、０≦ｙ≦１、０≦ｚ≦１、０≦ａ≦１、ＭはＡｌ、Ｍｇ、Ｎｂ、Ｔｉ、Ｃｕ、Ｚｎ、Ｃｒより選ばれる１種類以上の元素）で表される複合金属酸化物、リチウムバナジウム化合物（ＬｉＶ２Ｏ５）、オリビン型ＬｉＭＰＯ４（ただし、Ｍは、Ｃｏ、Ｎｉ、Ｍｎ、Ｆｅ、Ｍｇ、Ｎｂ、Ｔｉ、Ａｌ、Ｚｒより選ばれる１種類以上の元素又はＶＯを示す）、チタン酸リチウム（Ｌｉ４Ｔｉ５Ｏ１２）、ＬｉＮｉｘＣｏｙＡｌｚＯ２（０．９＜ｘ＋ｙ＋ｚ＜１．１）等の複合金属酸化物が挙げられる。 (Positive electrode active material)
Examples of the positive electrode active material include occlusion and release of lithium ions, desorption and insertion (intercalation) of lithium ions, or doping and dedoping of lithium ions and counter anions (for example, PF 6 − ) of the lithium ions. The electrode is not particularly limited as long as it can be reversibly advanced, and a known electrode active material can be used. For example, lithium cobaltate (LiCoO 2 ), lithium nickelate (LiNiO 2 ), lithium manganese spinel (LiMn 2 O 4 ), and the general formula: LiNi x Co y Mn z MaO 2 (x + y + z + a = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, 0 ≦ a ≦ 1, and M is one or more elements selected from Al, Mg, Nb, Ti, Cu, Zn, and Cr) Oxide, lithium vanadium compound (LiV 2 O 5 ), olivine type LiMPO 4 (where M is one or more elements selected from Co, Ni, Mn, Fe, Mg, Nb, Ti, Al, Zr, or VO) shown), and composite metal oxides of lithium titanate (Li 4 Ti 5 O 12) , LiNi x Co y Al z O 2 (0.9 <x + y + z <1.1) , etc.

（正極バインダー及び正極導電助剤）
バインダー及び導電助剤には、上述した負極２０に用いる材料を用いることができる。また、バインダー及び導電助剤の含有量も、上述した負極２０における含有量と同様の含有量を採用すればよい。添加する場合にはバインダーの添加量は、正極活物質の質量に対して２〜３０質量％であることが好ましい。導電助剤の添加量は、正極活物質の質量に対して１〜５０質量％であることが好ましい。 (Positive electrode binder and positive electrode conductive additive)
The material used for the negative electrode 20 mentioned above can be used for a binder and a conductive support agent. Moreover, what is necessary is just to employ | adopt content similar to content in the negative electrode 20 mentioned above also about content of a binder and a conductive support agent. When adding, it is preferable that the addition amount of a binder is 2-30 mass% with respect to the mass of a positive electrode active material. It is preferable that the addition amount of a conductive support agent is 1-50 mass% with respect to the mass of a positive electrode active material.

上述した構成要素により、電極１０、２０は、通常用いられる方法により作製できる。例えば、活物質（正極活物質または負極活物質）、バインダー（正極バインダーまたは負極バインダー）、溶媒、及び、導電助剤（正極導電助剤または負極導電助剤）を含む塗料を集電体上に塗布し、集電体上に塗布された塗料中の溶媒を除去することにより製造することができる。   With the components described above, the electrodes 10 and 20 can be produced by a commonly used method. For example, a paint containing an active material (a positive electrode active material or a negative electrode active material), a binder (a positive electrode binder or a negative electrode binder), a solvent, and a conductive additive (a positive electrode conductive additive or a negative electrode conductive aid) is placed on the current collector. It can manufacture by apply | coating and removing the solvent in the coating material apply | coated on the electrical power collector.

（セパレータ）
セパレータは、電解液に対して安定であり、保液性に優れていれば特に制限はないが、一般的にはポリエチレン、ポリプロピレン等のポリオレフィンの多孔質シート、又は不織布が挙げられる。 (Separator)
The separator is not particularly limited as long as it is stable with respect to the electrolytic solution and has excellent liquid retention, but generally includes a porous sheet of polyolefin such as polyethylene and polypropylene, or a nonwoven fabric.

（電解質）
電解質は、正極活物質層１４、負極活物質層２４、及び、セパレータ１８の内部に含有させるものである。電解質としては、特に限定されず、例えば、本実施形態では、リチウム塩を含む電解液（電解質水溶液、有機溶媒を使用する電解質溶液）を使用することができる。ただし、電解質水溶液は電気化学的に分解電圧が低いことにより、充電時の耐用電圧が低く制限されるので、有機溶媒を使用する電解液（非水電解質溶液）であることが好ましい。電解液としては、リチウム塩を非水溶媒（有機溶媒）に溶解したものが好適に使用される。リチウム塩としては特に限定されず、リチウムイオン二次電池の電解質として用いられるリチウム塩を用いることができる。例えば、リチウム塩としては、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＣｌＯ４、ＬｉＦＳＩ、ＬｉＢＯＢ等の無機酸陰イオン塩、ＬｉＣＦ３ＳＯ３、（ＣＦ３ＳＯ２）２ＮＬｉ等の有機酸陰イオン塩等を用いることができる。 (Electrolytes)
The electrolyte is contained in the positive electrode active material layer 14, the negative electrode active material layer 24, and the separator 18. The electrolyte is not particularly limited, and for example, in the present embodiment, an electrolytic solution containing a lithium salt (electrolyte aqueous solution, electrolyte solution using an organic solvent) can be used. However, the electrolyte aqueous solution is preferably an electrolyte solution (non-aqueous electrolyte solution) using an organic solvent because the electrochemical decomposition voltage is low, so that the withstand voltage during charging is limited to a low level. As the electrolytic solution, a lithium salt dissolved in a non-aqueous solvent (organic solvent) is preferably used. It does not specifically limit as lithium salt, The lithium salt used as an electrolyte of a lithium ion secondary battery can be used. For example, as the lithium salt, inorganic acid anion salts such as LiPF 6 , LiBF 4 , LiClO 4 , LiFSI, and LiBOB, organic acid anion salts such as LiCF 3 SO 3 , (CF 3 SO 2 ) 2 NLi, and the like are used. be able to.

また、有機溶媒としては、例えば、エチレンカーボネート、プロピレンカーボネート、フルオロエチレンカーボネート等の非プロトン性高誘電率溶媒や、ジメチルカーボネート、エチルメチルカーボネート、等の酢酸エステル類あるいはプロピオン酸エステル類等の非プロトン性低粘度溶媒が挙げられる。これらの非プロトン性高誘電率溶媒と非プロトン性低粘度溶媒を適当な混合比で併用することが望ましい。更には、イミダゾリウム、アンモニウム、及びピリジニウム型のカチオンを用いたイオン性液体を使用することができる。対アニオンは特に限定されるものではないが、ＢＦ４ −、ＰＦ６ −、（ＣＦ３ＳＯ２）２Ｎ−等が挙げられる。イオン性液体は前述の有機溶媒と混合して使用することが可能である。
電解液のリチウム塩の濃度は、電気伝導性の点から、０．５〜２．０Ｍが好ましい。なお、この電解質の温度２５℃における導電率は０．０１Ｓ／ｍ以上であることが好ましく、電解質塩の種類あるいはその濃度により調整される。 Examples of the organic solvent include aprotic high dielectric constant solvents such as ethylene carbonate, propylene carbonate, and fluoroethylene carbonate; aprotic acids such as dimethyl carbonate and ethyl methyl carbonate; and aprotic esters such as propionic acid esters. Low viscosity solvent. It is desirable to use these aprotic high dielectric constant solvents and aprotic low viscosity solvents in combination at an appropriate mixing ratio. Furthermore, ionic liquids using imidazolium, ammonium, and pyridinium type cations can be used. The counter anion is not particularly limited, and examples thereof include BF 4 − , PF 6 − , (CF 3 SO 2 ) 2 N − and the like. The ionic liquid can be used by mixing with the organic solvent described above.
The concentration of the lithium salt in the electrolytic solution is preferably 0.5 to 2.0 M from the viewpoint of electrical conductivity. The conductivity of the electrolyte at 25 ° C. is preferably 0.01 S / m or more, and is adjusted by the type of electrolyte salt or its concentration.

電解質を固体電解質やゲル電解質とする場合には、ポリ（ビニリデンフルオライド）等を高分子材料として含有することが可能である。
更に、本実施形態の電解液中には、必要に応じて各種添加剤を添加してもよい。添加剤としては、例えば、サイクル寿命向上を目的としたビニレンカーボネート、メチルビニレンカーボネート等や、過充電防止を目的としたビフェニル、アルキルビフェニル等や、脱酸や脱水を目的とした各種カーボネート化合物、各種カルボン酸無水物、各種含窒素及び含硫黄化合物が挙げられる。 When the electrolyte is a solid electrolyte or gel electrolyte, poly (vinylidene fluoride) or the like can be contained as a polymer material.
Furthermore, you may add various additives in the electrolyte solution of this embodiment as needed. Examples of additives include vinylene carbonate and methyl vinylene carbonate for the purpose of improving cycle life, biphenyl and alkyl biphenyl for the purpose of preventing overcharge, various carbonate compounds for the purpose of deoxidation and dehydration, Carboxylic anhydride, various nitrogen-containing and sulfur-containing compounds can be mentioned.

（ケース）
ケース５０は、その内部に積層体３０及び電解液を密封するものである。ケース５０は、電解液の外部への漏出や、外部からのリチウムイオン二次電池１００内部への水分等の侵入等を抑止できる物であれば特に限定されない。例えば、ケース５０として、図２に示すように、金属箔５２を高分子膜５４で両側からコーティングした金属ラミネートフィルムを利用できる。金属箔５２としては例えばアルミ箔を、高分子膜５４としてはポリプロピレン等の膜を利用できる。例えば、外側の高分子膜５４の材料としては融点の高い高分子、例えば、ポリエチレンテレフタレート（ＰＥＴ）、ポリアミド等が好ましく、内側の高分子膜５４の材料としてはポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）等が好ましい。 (Case)
The case 50 seals the laminated body 30 and the electrolytic solution therein. The case 50 is not particularly limited as long as it can suppress leakage of the electrolytic solution to the outside and entry of moisture and the like into the lithium ion secondary battery 100 from the outside. For example, as the case 50, as shown in FIG. 2, a metal laminate film in which a metal foil 52 is coated with a polymer film 54 from both sides can be used. For example, an aluminum foil can be used as the metal foil 52 and a film such as polypropylene can be used as the polymer film 54. For example, the material of the outer polymer film 54 is preferably a polymer having a high melting point, such as polyethylene terephthalate (PET) or polyamide, and the material of the inner polymer film 54 is polyethylene (PE) or polypropylene (PP). Etc. are preferred.

（リード）
リード６０、６２は、アルミ等の導電材料から形成されている。
そして、公知の方法により、リード６０、６２を正極集電体１２、負極集電体２２にそれぞれ溶接し、正極１０の正極活物質層１４と負極２０の負極活物質層２４との間にセパレータ１８を挟んだ状態で、電解液と共にケース５０内に挿入し、ケース５０の入り口をシールすればよい。
(Lead)
The leads 60 and 62 are made of a conductive material such as aluminum.
Then, the leads 60 and 62 are welded to the positive electrode current collector 12 and the negative electrode current collector 22 by a known method, respectively, and a separator is provided between the positive electrode active material layer 14 of the positive electrode 10 and the negative electrode active material layer 24 of the negative electrode 20. 18 may be inserted into the case 50 together with the electrolytic solution with the 18 interposed therebetween, and the entrance of the case 50 may be sealed.

以上、本発明の好適な実施形態について説明したが、本発明は上記実施形態に限定されるものではない。本発明は、その要旨を逸脱しない範囲で様々な変形が可能である。   The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. The present invention can be variously modified without departing from the gist thereof.

以下、実施例によって本発明を更に詳細に説明するが、本発明はこれらの実施例に限定されるものではない。   EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

（実施例１）
まず、原料粉としてＳｉ粉［ワイドテクノ社製、Ｄ５０＝１２０ｎｍ、二次粒子径：１μｍ］を準備した。０．２Ｍクエン酸水溶液の質量とＴｉ（ＯＣ４Ｈ９）４質量が５０：１２．９となるように混合し、２０時間１００℃撹拌還流した。その後、Ｔｉ（ＯＣ４Ｈ９）４質量１２．９に対してＡｌ（ＮＯ３）３・９Ｈ２Ｏ質量、ＮＨ４Ｈ２ＰＯ４質量、エチレングリコール質量が２．５：７．７：０．６となるように添加し、１時間撹拌した。さらに、ＡｌとＴｉとＰＯ４の合計質量とＳｉ質量が９５：５となる量のＳｉ粉を加え、スプレードライヤー［ビュッヒ社製、Ｂ−２９０］２００℃で乾燥粉末とした。その粉末を５００℃、４時間、８００℃、５時間Ｎ２中で焼成し、実施例１の負極活物質を得た。 Example 1
First, Si powder [Wide Techno Co., D50 = 120 nm, secondary particle size: 1 μm] was prepared as a raw material powder. The mass of 0.2 M citric acid aqueous solution and the mass of Ti (OC 4 H 9 ) 4 were mixed so as to be 50: 12.9, and the mixture was stirred and refluxed at 100 ° C. for 20 hours. Thereafter, Ti Al (NO 3) with respect to (OC 4 H 9) 4 mass 12.9 3 · 9H 2 O mass, NH 4 H 2 PO 4 wt of ethylene glycol by weight is 2.5: 7.7: 0 6 and stirred for 1 hour. Furthermore, Si powder was added in an amount such that the total mass of Al, Ti, and PO 4 and the Si mass was 95: 5, and a spray dryer (Buch Co., B-290) was made into a dry powder at 200 ° C. The powder was fired in N 2 at 500 ° C. for 4 hours, 800 ° C. for 5 hours, and the negative electrode active material of Example 1 was obtained.

＜Ａｌ、Ｔｉ、Ｐの各質量％とリン酸塩質量％の測定＞
実施例１の負極活物質をフッ化水素酸に溶解し、誘導結合プラズマ発光分光分析装置（ＩＣＰ−ＡＥＳ）［島津製作所製ＩＣＰＳ−８１００ＣＬ］を用い、Ａｌ、Ｔｉ、Ｐ、Ｓｉを定量した。その数値によりＡｌ、Ｔｉ、Ｐの各質量％を算出した。また、ＡｌｘＴｉｙ（１−ｘ）ＰＯ４に換算したリン酸塩質量とＳｉ質量により、Ｓｉ質量に対するリン酸塩の質量％を算出した。 <Measurement of each mass% of Al, Ti, P and phosphate mass%>
The negative electrode active material of Example 1 was dissolved in hydrofluoric acid, and Al, Ti, P, and Si were quantified using an inductively coupled plasma emission spectrometer (ICP-AES) [ICPS-8100CL manufactured by Shimadzu Corporation]. Each mass% of Al, Ti, and P was calculated from the numerical value. Further, the phosphate mass and Si mass in terms of Al x Ti y (1-x ) PO 4, was calculated weight percent of phosphate for Si mass.

＜リン酸塩の平均一次粒径とＳｉを主成分とする負極活物質粒子の平均二次粒径の測定＞
実施例１の負極活物質を透過型電子顕微鏡（ＴＥＭ）［日本電子社製、ＪＥＭ−３０００Ｆ］による観察と付属のＥＤＳ（ＴＥＭ−ＥＤＳ）による組成マッピングにより、５視野の画像を得た。その結果、透過型電子顕微鏡観察によりＳｉの二次粒子の表面にリン酸塩が被覆されているのが確認された。
また、その５視野の画像よりリン酸塩の平均一次粒径と、そのリン酸塩が付着しているＳｉを主成分とする負極活物質粒子の平均二次粒径を算出した。 <Measurement of Average Primary Particle Size of Phosphate and Average Secondary Particle Size of Negative Electrode Active Material Particles Mainly Containing Si>
By observing the negative electrode active material of Example 1 with a transmission electron microscope (TEM) [manufactured by JEOL Ltd., JEM-3000F] and composition mapping with an attached EDS (TEM-EDS), images of five fields of view were obtained. As a result, it was confirmed by observation with a transmission electron microscope that the surface of secondary particles of Si was coated with phosphate.
Further, the average primary particle size of the phosphate and the average secondary particle size of the negative electrode active material particles mainly composed of Si to which the phosphate was adhered were calculated from the images of the five fields of view.

＜負極の作製＞
実施例１の負極活物質を用いた電極（負極）を作製した。負極活物質と、導電助剤としてのアセチレンブラック（ＡＢ）とを混合して混合粉末を得た。また、Ｎ−メチルピロリドン（ＮＭＰ）にポリアミドイミド樹脂［日立化成社製、ＨＰＣ−１０００］を溶解させた。この溶液と、複合粉末とＡＢとの混合粉末と、を混合してスラリーを調製した。負極活物質、ＡＢおよびバインダー（固形分）の配合比は、質量比で３７：３７：２６とした。調製したスラリーを、厚さ１８μｍの電解銅箔（集電体）の表面にドクターブレードを用いて塗布し、銅箔上に負極活物質層を形成した。その後、１１０℃で１時間乾燥し、負極活物質層からＮＭＰを揮発させて除去した。乾燥後、ロールプレス機により、集電体と負極活物質層を強固に密着接合させた。これを３００℃で１時間加熱硬化させて、活物質層の厚さが１５μｍ程度の電極とした。 <Production of negative electrode>
An electrode (negative electrode) using the negative electrode active material of Example 1 was produced. A negative electrode active material and acetylene black (AB) as a conductive additive were mixed to obtain a mixed powder. Further, a polyamideimide resin [manufactured by Hitachi Chemical Co., Ltd., HPC-1000] was dissolved in N-methylpyrrolidone (NMP). This solution was mixed with the mixed powder of the composite powder and AB to prepare a slurry. The compounding ratio of the negative electrode active material, AB, and binder (solid content) was 37:37:26 by mass ratio. The prepared slurry was applied to the surface of an electrolytic copper foil (current collector) having a thickness of 18 μm using a doctor blade, and a negative electrode active material layer was formed on the copper foil. Then, it dried at 110 degreeC for 1 hour and volatilized and removed NMP from the negative electrode active material layer. After drying, the current collector and the negative electrode active material layer were firmly and closely joined with a roll press. This was heated and cured at 300 ° C. for 1 hour to obtain an electrode having an active material layer thickness of about 15 μm.

＜ハーフセルの作製＞
上記の手順で作製した実施例１の電極を評価極として用い、リチウム二次電池（ハーフセル）を作製した。対極は、金属リチウム箔とした。その後、セパレータ（材質：ポリプロピレン）を評価極と対極との間に挟装して電極体電池とした。この電極体電池を電池ケース（に収容した。また、電池ケースには、フルオロエチレンカーボネートとジメチルカーボネートとを４：６（体積比）で混合した混合溶媒にＬｉＰＦ６を１Ｍの濃度で溶解した非水電解質を注入した。電池ケースを密閉して、ハーフセルを得た。 <Fabrication of half cell>
A lithium secondary battery (half cell) was produced using the electrode of Example 1 produced by the above procedure as an evaluation electrode. The counter electrode was a metal lithium foil. Thereafter, a separator (material: polypropylene) was sandwiched between the evaluation electrode and the counter electrode to obtain an electrode body battery. This electrode body battery was housed in a battery case (in addition, LiPF 6 was dissolved at a concentration of 1M in a mixed solvent in which fluoroethylene carbonate and dimethyl carbonate were mixed at a volume ratio of 4: 6. Water electrolyte was poured in. The battery case was sealed to obtain a half cell.

＜ハーフセルの充放電試験＞
上記の手順で作製した実施例１のハーフセルに充放電試験［東洋システム社製、ＴＯＳＣＡＴ−３０００］を行い、初期放電容量およびサイクル特性を評価した。充放電試験は、まず２５℃の温度環境のもと、金属Ｌｉ基準で充電終止電圧０．０１Ｖまで０．０５Ｃの定電流で充電を行った後、放電終止電圧１．６Ｖまで０．０５Ｃの定電流で放電を行い、合わせて２サイクル行った。その後、充電終止電圧０．０１Ｖまで０．２Ｃの定電流で充電を行った後、放電終止電圧１．６Ｖまで０．２Ｃの定電流で放電を行い、１００サイクル行った。０．２Ｃでの最初の放電容量を初期容量とし、その初期容量を１００％とし、各サイクル後の容量維持率を算出した。ここで、本明細書では、「充電」は評価極の活物質がＬｉを吸蔵する方向、「放電」は評価極の活物質がＬｉを放出する方向、とする。 <Charge / discharge test of half cell>
The half cell of Example 1 produced by the above procedure was subjected to a charge / discharge test [TOSCAT-3000, manufactured by Toyo System Co., Ltd.] to evaluate the initial discharge capacity and cycle characteristics. In the charge / discharge test, first, under a temperature environment of 25 ° C., the battery was charged at a constant current of 0.05 C to a charge end voltage of 0.01 V on the basis of metal Li, and then 0.05 C to a discharge end voltage of 1.6 V. Discharge was performed at a constant current, and two cycles were performed in total. Thereafter, the battery was charged with a constant current of 0.2 C to a charge end voltage of 0.01 V, and then discharged with a constant current of 0.2 C to a discharge end voltage of 1.6 V, followed by 100 cycles. The initial discharge capacity at 0.2 C was taken as the initial capacity, the initial capacity was taken as 100%, and the capacity retention rate after each cycle was calculated. Here, in this specification, “charge” is a direction in which the active material of the evaluation electrode occludes Li, and “discharge” is a direction in which the active material of the evaluation electrode releases Li.

（実施例２）
ＡｌとＴｉとＰＯ４の合計質量とＳｉ質量の比が９０：１０となる量のＳｉ粉を加えること以外は、実施例１と同様の処理を行い、実施例２の負極活物質を得た。また、実施例１と同様の測定、負極、ハーフセルの作製、充放電試験を実施した。 (Example 2)
A negative electrode active material of Example 2 was obtained by performing the same treatment as in Example 1 except that Si powder was added in such an amount that the ratio of the total mass of Al, Ti, and PO 4 to the mass of Si was 90:10. . Moreover, the same measurement as Example 1, the preparation of a negative electrode and a half cell, and the charge / discharge test were implemented.

（実施例３）
Ｔｉ（ＯＣ４Ｈ９）４質量１２．９に対してＡｌ（ＮＯ３）３・９Ｈ２Ｏ質量、ＮＨ４Ｈ２ＰＯ４質量、エチレングリコール質量が２．５：９．２：０．６となるように添加すること以外は実施例２と同様の処理を行い、実施例３の負極活物質を得た。また、実施例１と同様の測定、負極、ハーフセルの作製、充放電試験を実施した。 (Example 3)
Ti (OC 4 H 9) 4 Al (NO 3) with respect to the mass 12.9 3 · 9H 2 O mass, NH 4 H 2 PO 4 wt of ethylene glycol by weight is 2.5: 9.2: 0.6 The negative electrode active material of Example 3 was obtained in the same manner as in Example 2 except that the addition was performed. Moreover, the same measurement as Example 1, the preparation of a negative electrode and a half cell, and the charge / discharge test were implemented.

（実施例４）
Ｔｉ（ＯＣ４Ｈ９）４質量１２．９に対してＡｌ（ＮＯ３）３・９Ｈ２Ｏ質量、ＮＨ４Ｈ２ＰＯ４質量、エチレングリコール質量が３．０：７．７：０．６となるように添加すること以外は実施例２と同様の処理を行い、実施例４の負極活物質を得た。また、実施例１と同様の測定、負極、ハーフセルの作製、充放電試験を実施した。 Example 4
Ti (OC 4 H 9) 4 Al (NO 3) with respect to the mass 12.9 3 · 9H 2 O mass, NH 4 H 2 PO 4 wt of ethylene glycol by weight is 3.0: 7.7: 0.6 The negative electrode active material of Example 4 was obtained by performing the same treatment as in Example 2 except that the addition was performed. Moreover, the same measurement as Example 1, the preparation of a negative electrode and a half cell, and the charge / discharge test were implemented.

（実施例５）
ＡｌとＴｉとＰＯ４の合計質量とＳｉ質量の比が８０：２０となる量のＳｉ粉を加えること以外は、実施例１と同様の処理を行い、実施例５の負極活物質を得た。また、実施例１と同様の測定、負極、ハーフセルの作製、充放電試験を実施した。 (Example 5)
A negative electrode active material of Example 5 was obtained by performing the same treatment as Example 1 except that Si powder was added in an amount such that the ratio of the total mass of Al, Ti, and PO 4 to the mass of Si was 80:20. . Moreover, the same measurement as Example 1, the preparation of a negative electrode and a half cell, and the charge / discharge test were implemented.

（実施例６）
ＡｌとＴｉとＰＯ４の合計量とＳｉ質量の比が７０：３０となる量のＳｉ粉を加えること以外は、実施例１と同様の処理を行い、実施例６の負極活物質を得た。また、実施例１と同様の測定、負極、ハーフセルの作製、充放電試験を実施した。 (Example 6)
A negative electrode active material of Example 6 was obtained in the same manner as in Example 1 except that Si powder was added in such an amount that the ratio of the total amount of Al, Ti, and PO 4 to the mass of Si was 70:30. . Moreover, the same measurement as Example 1, the preparation of a negative electrode and a half cell, and the charge / discharge test were implemented.

（比較例１）
ＡｌとＴｉとＰＯ４の合計質量とＳｉ質量の比が６０：４０となる量のＳｉ粉を加えること以外は、実施例１と同様の処理を行い、比較例１の負極活物質を得た。また、実施例１と同様の測定、負極、ハーフセルの作製、充放電試験を実施した。 (Comparative Example 1)
A negative electrode active material of Comparative Example 1 was obtained in the same manner as in Example 1 except that Si powder was added in such an amount that the ratio of the total mass of Al, Ti, and PO 4 to the mass of Si was 60:40. . Moreover, the same measurement as Example 1, the preparation of a negative electrode and a half cell, and the charge / discharge test were implemented.

（比較例２）
Ｓｉ粉［ワイドテクノ社製、Ｄ５０＝１２０ｎｍ、二次粒子径：１μｍ］質量とＬｉ４Ｔｉ５Ｏ１２質量の比が８０：２０となるように混合し、ジルコニアボールを用いた遊星ボールミルにて３００ｒｐｍ６時間粉砕し、比較例２の負極活物質を得た。また、実施例１と同様の測定、負極、ハーフセルの作製、充放電試験を実施した。 (Comparative Example 2)
In a planetary ball mill using zirconia balls, Si powder [Wide Techno Co., D50 = 120 nm, secondary particle size: 1 μm] is mixed so that the mass ratio of Li 4 Ti 5 O 12 is 80:20. The negative electrode active material of Comparative Example 2 was obtained by grinding at 300 rpm for 6 hours. Moreover, the same measurement as Example 1, the preparation of a negative electrode and a half cell, and the charge / discharge test were implemented.

（比較例３）
Ｓｉ粉［ワイドテクノ社製、Ｄ５０＝１２０ｎｍ、二次粒子径：１μｍ］を比較例３の負極活物質とした。また、実施例１と同様の測定、負極、ハーフセルの作製、充放電試験を実施した。 (Comparative Example 3)
Si powder [Wide Techno Co., D50 = 120 nm, secondary particle size: 1 μm] was used as the negative electrode active material of Comparative Example 3. Moreover, the same measurement as Example 1, the preparation of a negative electrode and a half cell, and the charge / discharge test were implemented.

表１に、実施例１〜６及び比較例１〜３のＡｌ，Ｔｉ，Ｐの各質量％とリン酸塩質量％、リン酸塩の平均一次粒径とＳｉを主成分とする負極活物質粒子の平均二次粒径、負極活物質の充放電試験結果を示す。   Table 1 shows negative electrode active materials mainly composed of Al, Ti, and P in each of Examples 1 to 6 and Comparative Examples 1 to 3 and phosphate mass%, the average primary particle diameter of phosphate, and Si. The average secondary particle diameter of particle | grains and the charging / discharging test result of a negative electrode active material are shown.

Figure 2016157631
Figure 2016157631

表１から明らかなように、比較例１〜３の負極活物質では、容量維持率が低下していることが確認された。比較例１では、Ｓｉ二次粒子径に対してリン酸塩一次粒子径が大きくなり、充放電時のＳｉ二次粒子の崩壊の抑制に対してリン酸塩の寄与が小さくなることで、容量維持率が低下したといえる。また、比較例２、及び３では、リン酸塩が無いため、充放電時のＳｉ一次粒子の膨張収縮によるＳｉ二次粒子の崩壊が抑制できず、容量維持率が低下したといえる。一方、実施例１〜６の負極活物質では、リン酸塩により充放電によるＳｉ一次粒子の膨張収縮時の二次粒子の崩壊をリン酸塩で抑制され、容量維持率が向上することが確認された。この負極活物質を用いて作製したリチウム二次電池は、容量維持率が高いことが確認され、本発明の目的を達成できることが確認された。  As is clear from Table 1, it was confirmed that the capacity retention rate was reduced in the negative electrode active materials of Comparative Examples 1 to 3. In Comparative Example 1, the phosphate primary particle size is larger than the Si secondary particle size, and the contribution of the phosphate to the suppression of the collapse of the Si secondary particles during charging / discharging is reduced. It can be said that the maintenance rate has decreased. Further, in Comparative Examples 2 and 3, since there is no phosphate, it can be said that the collapse of the Si secondary particles due to the expansion and contraction of the Si primary particles during charge and discharge cannot be suppressed, and the capacity maintenance rate is reduced. On the other hand, in the negative electrode active materials of Examples 1 to 6, it was confirmed that the secondary particles were prevented from collapsing by phosphate when the Si primary particles were expanded and contracted by charging and discharging, and the capacity retention rate was improved. It was done. The lithium secondary battery produced using this negative electrode active material was confirmed to have a high capacity retention rate, and it was confirmed that the object of the present invention could be achieved.

以上説明した通り、本発明の負極活物質及びリチウム二次電池は、容量維持率が高く、また、容量が大きく電池の小型化を実現できるので、リチウム二次電池及びそれらを備える各種機器、設備、システム等に広く且つ有効に利用可能である。    As described above, the negative electrode active material and the lithium secondary battery of the present invention have a high capacity retention rate, and have a large capacity and can realize downsizing of the battery. Therefore, the lithium secondary battery and various devices and equipment including them are provided. It can be used widely and effectively in systems and the like.

１・・・Ｓｉを主成分とする負極活物質粒子の一次粒子
２・・・Ｓｉを主成分とする負極活物質粒子の二次粒子
３・・・リン酸塩粒子
９・・・負極活物質
１０・・・正極
１２・・・正極集電体
１４・・・正極活物質層
１８・・・セパレータ
２０・・・負極
２２・・・負極集電体
２４・・・負極活物質層
３０・・・積層体
５０・・・外装体
５２・・・金属箔
５４・・・高分子膜
６０・・・正極リード
６２・・・負極リード
１００・・・リチウムイオン二次電池

DESCRIPTION OF SYMBOLS 1 ... Primary particle | grains of negative electrode active material particle which has Si as a main component 2 ... Secondary particle of negative electrode active material particle which has Si as a main component 3 ... Phosphate particle 9 ... Negative electrode active material DESCRIPTION OF SYMBOLS 10 ... Positive electrode 12 ... Positive electrode collector 14 ... Positive electrode active material layer 18 ... Separator 20 ... Negative electrode 22 ... Negative electrode collector 24 ... Negative electrode active material layer 30 ... Laminate 50 ... outer package 52 ... metal foil 54 ... polymer film 60 ... positive electrode lead 62 ... negative electrode lead 100 ... lithium ion secondary battery

Claims (4)

Ｓｉを主成分とする負極活物質粒子と、その表面に付着するリン酸塩と、を含有し、
前記リン酸塩は、ＡｌｘＴｉｙ（１−ｘ）ＰＯ４（０＜ｘ＜１、０．７５＜ｙ＜１）で表される化合物であると共に、
ＡｌとＴｉとＰの合計質量に対して
Ａｌが、６．１ｍａｓｓ％以上８．３ｍａｓｓ％以下、
Ｔｉが、５４．６ｍａｓｓ％以上６１．７ｍａｓｓ％以下、
Ｐが、３２．１ｍａｓｓ％以上３８．６ｍａｓｓ％以下、
であり、
前記リン酸塩は、前記負極活物質粒子中のＳｉに対して、
４．７ｍａｓｓ％以上２６．９ｍａｓｓ％以下
で含有されていることを特徴とする負極活物質。 Containing negative electrode active material particles mainly composed of Si, and phosphate adhering to the surface thereof,
The phosphate is a compound represented by Al x Ti y (1-x) PO 4 (0 <x <1, 0.75 <y <1),
Al is 6.1 mass% or more and 8.3 mass% or less with respect to the total mass of Al, Ti, and P,
Ti is 54.6 mass% or more and 61.7 mass% or less,
P is 32.1 mass% or more and 38.6 mass% or less,
And
The phosphate is based on Si in the negative electrode active material particles.
A negative electrode active material, wherein the negative electrode active material is contained in an amount of 4.7 mass% to 26.9 mass%. 前記負極活物質粒子は二次粒子を構成し、その二次粒子の表面に前記リン酸塩が被覆されていることを特徴とする請求項１記載の負極活物質。   The negative electrode active material according to claim 1, wherein the negative electrode active material particles constitute secondary particles, and the phosphate is coated on a surface of the secondary particles. 前記リン酸塩の平均一次粒子径を前記二次粒子の平均二次粒子径で除した値が、０．２０以上０．４８以下であることを特徴とする請求項２に記載の負極活物質。   3. The negative electrode active material according to claim 2, wherein a value obtained by dividing the average primary particle diameter of the phosphate by the average secondary particle diameter of the secondary particles is 0.20 or more and 0.48 or less. . 請求項１〜３のいずれかに記載の負極活物質を用いた負極と、電解質と正極とを具備したリチウム二次電池。   The lithium secondary battery which comprised the negative electrode using the negative electrode active material in any one of Claims 1-3, the electrolyte, and the positive electrode.
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