JP4839180B2 - Carbon powder and manufacturing method thereof, negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, and lithium ion secondary battery - Google Patents

Carbon powder and manufacturing method thereof, negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, and lithium ion secondary battery Download PDF

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JP4839180B2
JP4839180B2 JP2006288835A JP2006288835A JP4839180B2 JP 4839180 B2 JP4839180 B2 JP 4839180B2 JP 2006288835 A JP2006288835 A JP 2006288835A JP 2006288835 A JP2006288835 A JP 2006288835A JP 4839180 B2 JP4839180 B2 JP 4839180B2
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真樹子 井尻
邦彦 江口
勝博 長山
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Description

本発明は、初回充放電効率が高い上、サイクル特性に優れており、特に電極密度が１．６ｇ／ｃｍ３超の高密度であっても、急速充電可能なリチウムイオン二次電池、該リチウムイオン二次電池を得るためのリチウムイオン二次電池用負極、該負極を得るためのリチウムイオン二次電池用負極材料、ならびに該負極材料の材料となる炭素粉末およびその製造方法に関する。 The present invention has high initial charge / discharge efficiency and excellent cycle characteristics, and in particular, a lithium ion secondary battery capable of rapid charging even when the electrode density is higher than 1.6 g / cm 3. The present invention relates to a negative electrode for a lithium ion secondary battery for obtaining an ion secondary battery, a negative electrode material for a lithium ion secondary battery for obtaining the negative electrode, a carbon powder as a material for the negative electrode material, and a method for producing the same.

近年、電子機器の小型化または高性能化に伴い、電池の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。このような状況のなか、エネルギー密度が高く、高電圧化が可能な電池として、リチウムイオン二次電池が注目されている。このリチウムイオン二次電池の負極を構成する負極材料としては、充放電特性に優れ、高い放電容量と電位平坦性とを示す黒鉛が主流となっている（例えば、特許文献１）。負極材料として使用される黒鉛としては、天然黒鉛、人造黒鉛などの黒鉛粒子、さらにはタール、ピッチを原料としたメソフェーズピッチ、例えば、メソフェーズ小球体などを熱処理して得られるメソフェーズ系黒鉛粒子が挙げられる。   In recent years, with the miniaturization or high performance of electronic devices, there is an increasing demand for higher energy density of batteries. Under such circumstances, lithium ion secondary batteries have attracted attention as batteries that have high energy density and can be increased in voltage. As a negative electrode material constituting the negative electrode of this lithium ion secondary battery, graphite that is excellent in charge / discharge characteristics and exhibits high discharge capacity and potential flatness has become the mainstream (for example, Patent Document 1). Examples of the graphite used as the negative electrode material include graphite particles such as natural graphite and artificial graphite, and mesophase-based graphite particles obtained by heat-treating mesophase pitch using tar and pitch as raw materials, for example, mesophase microspheres. It is done.

メソフェーズ小球体を黒鉛化して得た黒鉛粒子を負極材料に用いたリチウムイオン二次電池は、非常に良好な放電特性を示すが、該黒鉛粒子のプレス圧縮性が低く（高密度化し難く）、負極を高密度化することによる体積あたりのエネルギー密度向上に関しては、天然黒鉛または高結晶性の人造黒鉛よりも不利である。一方、天然黒鉛や高結晶性の人造黒鉛は、非常にプレス圧縮性が高い（高密度化し易い）が、配向性が強いため、電極を高密度化して高エネルギー密度化を図ろうとすると、急速充放電特性が著しく低下し、サイクル特性も劣悪となるため、かえってメソフェーズ小球体の黒鉛粒子よりもエネルギー密度が低い範囲でしか、良好な電池特性を示さないという大きな欠点がある。   A lithium ion secondary battery using graphite particles obtained by graphitizing mesophase spherules as a negative electrode material exhibits very good discharge characteristics, but the graphite particles have low press compressibility (not easily densified), In terms of improving the energy density per volume by increasing the density of the negative electrode, it is more disadvantageous than natural graphite or highly crystalline artificial graphite. On the other hand, natural graphite and highly crystalline artificial graphite have very high press-compressibility (easy to be densified), but their orientation is strong. Therefore, when trying to increase the density of electrodes and increase energy density, Since the charge / discharge characteristics are remarkably deteriorated and the cycle characteristics are also deteriorated, there is a great drawback that good battery characteristics are exhibited only in a range where the energy density is lower than that of graphite particles of mesophase spherules.

こうした黒鉛粒子の負極材料としての欠点を補うために、負極を作製する際に、異質な黒鉛粒子を混合し、調製して、前記欠点を改良している。
例えば、メソフェーズ小球体間の空隙が圧縮されがたいことを利用して、高結晶性の天然黒鉛あるいは人造黒鉛に、メソフェーズ小球体の黒鉛化物などを混合し、電極製造の圧延時に配向しやすい天然黒鉛、人造黒鉛を配向させないように負極を作製するなど、電極の空隙構造を保ち、高密度域での電池特性を低下させない方法が提案され（特許文献２）、同様に高結晶性の天然黒鉛、人造黒鉛の配向を防ぐために、メソフェーズピッチからの炭素繊維の黒鉛化物を混合する方法が提案されている（特許文献３、４）。 In order to compensate for the drawbacks of such graphite particles as a negative electrode material, when producing the negative electrode, foreign graphite particles are mixed and prepared to improve the above-mentioned drawbacks.
For example, by utilizing the fact that the gaps between mesophase spherules are difficult to compress, natural graphite or artificial graphite mixed with highly crystalline natural graphite or graphitized mesophase spherules, etc. are easily oriented during rolling in electrode manufacturing. A method has been proposed in which a negative electrode is prepared so that graphite and artificial graphite are not oriented, such as maintaining a void structure of the electrode and not deteriorating battery characteristics in a high density region (Patent Document 2). In order to prevent the orientation of artificial graphite, a method of mixing graphitized carbon fibers from mesophase pitch has been proposed (Patent Documents 3 and 4).

近年、リチウムイオン二次電池の放電容量の増大に対する要求は増しており、これに対応するためにさらに電極を高密度化すると、急速充放電性などの電池特性が低下する傾向があり、さらなる電極密度の高密度化の推進に、提案されている従来技術では限界があった。その理由として、メソフェーズ小球体の黒鉛粒子のような硬い成分と、天然黒鉛粒子などの柔らかい成分とを混合すると、混合組成にもよるが、柔らかい成分がより高密度化し、配向しやすいものであればあるほど、黒鉛粒子間での配向が助長され、黒鉛粒子間への電解液の浸透性が悪くなったり、リチウムイオンの出入りに支障をきたしたりするためと推定される。
すなわち、特許文献２または３，４のように、メソフェーズ小球体やメソフェーズピッチからの炭素繊維は、材質が硬いため、これを主材とすると負極の高密度化が困難となる。一方、天然黒鉛のような鱗片状黒鉛の添加量を多くすると、比較的低密度では、良好な電池特性を示すが、これを高密度化すると、電極内での密度の偏在と考えられる電池特性の劣化が起こる。 In recent years, the demand for an increase in the discharge capacity of lithium ion secondary batteries has increased, and if the electrode density is further increased in order to meet this demand, battery characteristics such as rapid charge / discharge characteristics tend to be reduced. There is a limit to the proposed prior art in promoting higher density. The reason is that if a hard component such as graphite particles of mesophase spherules and a soft component such as natural graphite particles are mixed, the soft component has a higher density and is easily oriented, depending on the mixed composition. It is presumed that the greater the orientation, the more the orientation between the graphite particles is promoted, the worse the permeability of the electrolyte solution between the graphite particles, and the hindrance to the entry and exit of lithium ions.
That is, as in Patent Document 2 or 3 and 4, carbon fibers from mesophase spherules and mesophase pitch are hard, so if this is the main material, it is difficult to increase the density of the negative electrode. On the other hand, if the amount of flake graphite such as natural graphite is increased, good battery characteristics are exhibited at relatively low density. However, when this density is increased, battery characteristics that are thought to be unevenly distributed in the electrode Degradation occurs.

また、メカノケミカル処理により親水化した黒鉛質粒子を負極材料に用いたリチウムイオン二次電池は、放電容量が高く、初回充放電効率が高いこと、また、該メカノケミカル処理により親水化した黒鉛質粒子に、非メカノケミカル処理黒鉛質粒子を添加してなる負極材料を用いたリチウムイオン二次電池は、その急速充電効率が一段と向上することが知られている（特許文献５）。
しかし、この場合も、負極の電極密度を１．６ｇ／ｃｍ３超の高密度にすると、放電容量が大きくならず、急速充電効率も不満足であった。 In addition, lithium ion secondary batteries using graphite particles hydrophilized by mechanochemical treatment as a negative electrode material have a high discharge capacity and high initial charge / discharge efficiency, and the graphite material hydrophilized by mechanochemical treatment. A lithium ion secondary battery using a negative electrode material obtained by adding non-mechanochemically treated graphite particles to particles is known to further improve the rapid charging efficiency (Patent Document 5).
However, in this case as well, when the electrode density of the negative electrode was set to a high density exceeding 1.6 g / cm 3 , the discharge capacity was not increased, and the rapid charging efficiency was unsatisfactory.

特許文献１： 特公昭６２−２３４３３号公報
特許文献２： 特開平６−１６３０３２号公報
特許文献３： 特開２００１−１３５３０４号公報
特許文献４： 特開２００２−３３１０４号公報
特許文献５： 特開２００３−１３２８８９号公報 Patent Document 1: Japanese Patent Publication No. 62-23433 Patent Document 2: Japanese Patent Application Laid-Open No. 6-163032 Patent Document 3: Japanese Patent Application Laid-Open No. 2001-135304 Patent Document 4: Japanese Patent Application Laid-Open No. 2002-33104 Patent Document 5: Japanese Patent Application Laid-Open No. 2002-33104 No. 2003-132889

したがって、本発明は、初回充放電効率が高い上、サイクル特性に優れており、特に電極密度が１．６ｇ／ｃｍ３超の高密度であっても、急速充電可能なリチウムイオン二次電池、該リチウムイオン二次電池を得るためのリチウムイオン二次電池用負極、該負極を得るためのリチウムイオン二次電池用負極材料、ならびに該負極材料の材料となる炭素粉末およびその製造方法を提供することが目的である。 Therefore, the present invention has high initial charge / discharge efficiency and excellent cycle characteristics, and in particular, a lithium ion secondary battery that can be rapidly charged even when the electrode density is higher than 1.6 g / cm 3 , Provided are a negative electrode for a lithium ion secondary battery for obtaining the lithium ion secondary battery, a negative electrode material for a lithium ion secondary battery for obtaining the negative electrode, a carbon powder as a material for the negative electrode material, and a method for producing the same. Is the purpose.

本発明は、上記のような従来の黒鉛系リチウムイオン二次電池用負極材料の課題を解決するものである．本発明者は、炭素粒子について鋭意検討を行った結果、ジブチルフタレートの吸収量が下記範囲にあり、かつ下記式（１）を満たす炭素粒子を使用することにより、初回充放電効率が良く、かつ高密度域での電池特性（急速充放電特性、サイクル特性）が飛躍的に改善することを見出し、本発明を完成するに至った。本発明は、下記の通りである。   The present invention solves the problems of the conventional negative electrode materials for graphite-based lithium ion secondary batteries as described above. As a result of intensive studies on carbon particles, the present inventor has good initial charge and discharge efficiency by using carbon particles whose dibutyl phthalate absorption amount is in the following range and satisfies the following formula (1). The present inventors have found that battery characteristics (rapid charge / discharge characteristics, cycle characteristics) in a high density region are dramatically improved, and have completed the present invention. The present invention is as follows.

１．ジブチルフタレートの吸収量が１０ｃｍ３／１００ｇ以上、３０ｃｍ３／１００ｇ以下であり、かつ下記式（１）で示す密度比が４〜６．５であることを特徴とする炭素粉末。
密度比＝（圧力１ＭＰａをかけたときの密度）／（タップ密度）・・・・（１）
２．黒鉛材料と、下記式（１）で示される密度比および平均粒子径が該黒鉛材料よりも小さい炭素材料とをメカノケミカル処理した後、さらに結合剤を用いて、該黒鉛材料に該炭素材料を付着させることを特徴とする炭素粉末の製造方法。
密度比＝（圧力１ＭＰａをかけたときの密度）／（タップ密度）・・・・（１）
３．前記黒鉛材料の密度比が３〜９であり、平均粒子径が５０μｍ以下であることを特徴とする前記２の炭素粉末の製造方法。
４．黒鉛材料１００質量部と、下記式（１）で示される密度比および平均粒子径が該黒鉛材料よりも小さい炭素材料１〜５０質量部とをメカノケミカル処理した後、さらに結合剤を用いて、該黒鉛材料に該炭素材料を付着させることを特徴とするジブチルフタレートの吸収量が１０ｃｍ３／１００ｇ以上、３０ｃｍ３／１００ｇ以下であり、かつ下記式（１）で示す密度比が４〜６．５である前記２または３の炭素粉末の製造方法。
密度比＝（圧力１ＭＰａをかけたときの密度）／（タップ密度）・・・・（１） 1. Absorption of dibutyl phthalate 10 cm 3/100 g or more, 30 cm 3/100 g or less and a carbon powder density ratio represented by the following formula (1) is characterized in that it is a 4 to 6.5.
Density ratio = (Density when pressure is 1 MPa) / (Tap density) (1)
2. After mechanochemical treatment of the graphite material and a carbon material having a density ratio and an average particle diameter smaller than the graphite material represented by the following formula (1), the carbon material is further applied to the graphite material using a binder. A method for producing a carbon powder, characterized by adhering.
Density ratio = (Density when pressure is 1 MPa) / (Tap density) (1)
3. 2. The method for producing carbon powder as described in 2 above, wherein the density ratio of the graphite material is 3 to 9, and the average particle diameter is 50 μm or less.
4). After mechanochemical treatment of 100 parts by mass of the graphite material and 1 to 50 parts by mass of the carbon material having a density ratio and an average particle diameter represented by the following formula (1) smaller than the graphite material, using a binder, absorption of dibutyl phthalate for causing the graphite material is deposited the carbon material is 10 cm 3/100 g or more, or less 30 cm 3/100 g, and the density ratio shown by the following formula (1) is 4-6. 5. The method for producing the carbon powder according to 2 or 3, which is 5.
Density ratio = (Density when pressure is 1 MPa) / (Tap density) (1)

５．前記１の炭素粉末を含むことを特徴とするリチウムイオン二次電池用負極材料。
６．前記５のリチウムイオン二次電池用負極材料からなることを特徴とするリチウムイオン二次電池用負極。
７．前記６のリチウムイオン二次電池用負極を設けたことを特徴とするリチウムイオン二次電池。 5). A negative electrode material for a lithium ion secondary battery, comprising the carbon powder of 1.
6). 5. The negative electrode for a lithium ion secondary battery, comprising the negative electrode material for a lithium ion secondary battery according to 5 above.
7). A lithium ion secondary battery comprising the negative electrode for a lithium ion secondary battery according to 6 above.

本発明の炭素粉末は、これをリチウムイオン二次電池の負極材料に用いた場合、該電池の放電容量、初回充放電効率が高く、特に高密度化された負極を作製したときも、良好な急速充放電特性を示す。そのため、本発明の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効である。   When the carbon powder of the present invention is used as a negative electrode material for a lithium ion secondary battery, the discharge capacity of the battery and the initial charge / discharge efficiency are high. Shows rapid charge / discharge characteristics. Therefore, the lithium ion secondary battery of the present invention satisfies the recent demand for higher energy density of the battery, and is effective in reducing the size and performance of the mounted device.

以下、本発明を具体的に説明する。
［炭素粉末］
本発明の炭素粉末は、ジブチルフタレート（ＤＢＰ）の吸収量（以下、単にＤＢＰ吸収量とも称す）が１０ｃｍ３／１００ｇ以上、３０ｃｍ３／１００ｇ以下であり、かつ密度比が下記式（１）を満たすものである。
密度比＝（圧力１ＭＰａをかけたときの密度）／（タップ密度）・・・・（１） Hereinafter, the present invention will be specifically described.
[Carbon powder]
Carbon powder of this invention, the absorption amount of dibutyl phthalate (DBP) (hereinafter, simply referred to as DBP absorption) of 10 cm 3/100 g or more, 30 cm 3/100 g or less and the density ratio of the following formula (1) To meet.
Density ratio = (Density when pressure is 1 MPa) / (Tap density) (1)

ＤＢＰ吸収量は、通常カーボンブラックのような微小粒子のストラクチャー構造を定量するものであるが、リチウムイオン二次電池用負極を作製するときの結着剤の吸収量を知る目安になると考えられる。本発明においては、ＪＩＳ Ｋ６２１７−４：２００１に規定されたＢ法（へら練り法）に準拠した方法によって測定した。詳細は後記する。
なお、炭素粉末のうち、ファーネスカーボンブラックなどのように平均粒子径が数十ｎｍと小さいものはＤＢＰ吸収量が１００ｃｍ３／１００ｇ以上であるが、カーボンブラックよりも遥かに大きな平均粒子径を持つ黒鉛粒子は、ＤＢＰ吸収量は非常に小さく、一般的な天然黒鉛、人造黒鉛では２５ｃｍ３／１００ｇ程度であり、メソカーボン小球体の黒鉛化物のような黒鉛粒子では通常１０ｃｍ３／１００ｇ未満である。 DBP absorption usually quantifies the structure of fine particles such as carbon black, and is considered to be a measure for knowing the amount of binder absorbed when producing a negative electrode for a lithium ion secondary battery. In this invention, it measured by the method based on B method (squeezing method) prescribed | regulated to JISK6217-4: 2001. Details will be described later.
Among the carbon powder, although an average particle size, such as furnace carbon black is small and a few tens of nm is DBP absorption 100 cm 3/100 g or more, with a much larger average particle size than carbon black graphite particles, DBP absorption amount is very small, a typical natural graphite, artificial graphite is about 25 cm 3/100 g, is usually less than 10 cm 3/100 g is graphite particles, such as graphite product of mesocarbon spherules .

式（１）で定義される密度比は、炭素粉末を充填したとき、炭素粉末の形状、形態を維持する強さの程度、すなわち、耐圧縮性や硬さを見るための指標である。炭素粉末を軽く揺って充填した場合の密度、いわゆるタップ密度に比べ、１ＭＰａに加圧したときの密度と該タップ密度の比で示される指標の方が、電極密度が１．６ｇ／ｃｍ３超のような高密度となるように充填したときの耐圧縮性や硬さを適切に表示する。すなわち、該密度比が４〜６．５、好ましくは４．５〜６．３、より好ましくは４．８〜６．０であると、電解液の出入りが適度な炭素粉末の空隙量が確保され、電極密度が１．６ｇ／ｃｍ３超のときの耐圧縮性が良好であり、炭素粉末が潰れず、空隙が維持され、リチウムイオン二次電池の急速充放電効率を著しく向上することができる。該密度の測定方法は後記する。
なお、潰れやすい天然黒鉛、人造黒鉛の該密度比は７〜９と大きく、潰れにくい球晶黒鉛の該密度比は１〜３と小さい。 The density ratio defined by the formula (1) is an index for viewing the degree of strength for maintaining the shape and form of the carbon powder, that is, the compression resistance and hardness when the carbon powder is filled. Compared to the density when the carbon powder is lightly shaken and filled, that is, the so-called tap density, the index indicated by the ratio of the density when pressurized to 1 MPa and the tap density has an electrode density of 1.6 g / cm 3. Appropriate display of compression resistance and hardness when filled to a high density such as super. That is, when the density ratio is 4 to 6.5, preferably 4.5 to 6.3, and more preferably 4.8 to 6.0, the amount of voids in the carbon powder that allows the electrolyte solution to enter and exit is ensured. The compression resistance when the electrode density exceeds 1.6 g / cm 3 is good, the carbon powder is not crushed, the voids are maintained, and the rapid charge / discharge efficiency of the lithium ion secondary battery can be significantly improved. it can. A method for measuring the density will be described later.
In addition, the density ratio of natural graphite and artificial graphite which are easily crushed is as large as 7 to 9, and the density ratio of spherulite graphite which is not easily crushed is as small as 1 to 3.

リチウムイオン二次電池用負極材料（以下、単に負極材料とも記す）は、黒鉛または炭素材料を、通常、水系または有機系のバインダーの溶液または分散液に加えて、ペ−スト状の負極合剤に調製される。該負極合剤を集電材に塗布し、負極を作製するが、ペースト化に必要な媒体量は少ない方が該負極合剤の特性、および生産性の点から好都合である。本発明の炭素粉末も同様に負極材料に調製される。
ところで、ＤＢＰ吸収量の大きい炭素粉末は、これを流動可能なペ一ストにするために、多量の溶剤、結着剤を用いる必要があり、少量であると負極合剤を調製するのが困難である。したがって、炭素粉末からペースト状の負極合剤を調製する際の容易性、負極合剤の特性の点からは、ＤＢＰ吸収量の小さい炭素粉末が好ましく、例えば、メソカーボン小球体の黒鉛化物の方が天然黒鉛より好ましいのである。具体的なＤＢＰ吸収量は１０ｃｍ３／１００ｇ以上、３０ｃｍ３／１００ｇ以下であり、好ましくは１２〜２５ｃｍ３／１００ｇ、より好ましくは１４〜２２ｃｍ３／１００ｇである。 A negative electrode material for a lithium ion secondary battery (hereinafter, also simply referred to as a negative electrode material) is a paste-like negative electrode mixture in which graphite or a carbon material is usually added to a solution or dispersion of an aqueous or organic binder. To be prepared. The negative electrode mixture is applied to a current collector to produce a negative electrode, but it is advantageous from the viewpoint of the characteristics and productivity of the negative electrode mixture that the amount of medium required for forming a paste is smaller. The carbon powder of the present invention is similarly prepared as a negative electrode material.
By the way, a carbon powder having a large DBP absorption amount needs to use a large amount of a solvent and a binder in order to make it a flowable paste. If the amount is small, it is difficult to prepare a negative electrode mixture. It is. Therefore, from the viewpoint of ease of preparing a paste-like negative electrode mixture from carbon powder and the characteristics of the negative electrode mixture, carbon powder having a small DBP absorption amount is preferable. For example, graphitized mesocarbon spherulites are preferred. Is preferred over natural graphite. Specific DBP absorption 10 cm 3/100 g or more, or less 30 cm 3/100 g, preferably 12~25cm 3 / 100g, more preferably 14~22cm 3 / 100g.

しかし、メソカーボン小球体の黒鉛化物は天然黒鉛より硬く、大きいので、両者を混合し、圧縮して、電極密度が１．６ｇ／ｃｍ３超のような高密度な負極を作製した場合、柔らかい天然黒鉛が潰れ、メソカーボン小球体同士が形成する空隙に入り込み、空隙の大きさ、数を減少させ、天然黒鉛が先行して配向する。そのため、これを用いたリチウムイオン二次電池（以下、単に二次電池とも記す）においては、電解液が入る空隙が減少し、リチウムイオンの出入の機会、量が減少するので、急速充放電効率が低下する。なお、電極密度が１．６ｇ／ｃｍ３未満の場合には、該空隙の減少はほとんどなく、メソカーボン小球体の黒鉛化物と天然黒鉛の混合による急速充放電効率の向上が認められる。 However, since the graphitized mesocarbon spherules are harder and larger than natural graphite, they are mixed and compressed to produce a high-density negative electrode having an electrode density of more than 1.6 g / cm 3. The natural graphite is crushed and enters the voids formed by the mesocarbon microspheres, reducing the size and number of the voids, and the natural graphite is oriented in advance. Therefore, in the lithium ion secondary battery using this (hereinafter also referred to simply as a secondary battery), the gap for the electrolyte solution is reduced, and the opportunity and amount of lithium ion entry and exit are reduced. Decreases. When the electrode density is less than 1.6 g / cm 3 , there is almost no decrease in the voids, and rapid charge / discharge efficiency is improved by mixing the mesocarbon microsphere graphitized material with natural graphite.

本発明の炭素粉末は、結着剤や電解液の易吸収性に加えて、天然黒鉛よりもプレス圧縮されにくい粉体特性を合わせ持つので、これを用いた負極合剤を塗布した電極をプレス成形する際にも圧縮されがたく（密度比が小さい）、天然黒鉛などの易圧縮性の炭素材料に比べて、高密度化時においても、電極の空隙を保つことが可能である。   The carbon powder of the present invention has a powder property that is harder to press-compress than natural graphite, in addition to the easy absorbability of the binder and electrolyte, so press the electrode coated with the negative electrode mixture using this. It is difficult to compress even during molding (the density ratio is small), and it is possible to keep the gaps of the electrodes even when the density is increased as compared with a readily compressible carbon material such as natural graphite.

本発明の炭素粉末の結晶性は特に限定されないが、結晶性が高い方がより高エネルギー密度化ができるため、高い方が好ましい。好ましくはＸ線回折における格子面間隔ｄ００２が０．３４０ｎｍ以下、より好ましくは０．３３７ｎｍ以下である。なお、該格子面間隔ｄ００２は、Ｘ線としてＣｕＫα線を用い、高純度シリコンを標準物質に使用して、炭素粉末の（００２）面の回折ピークを測定し、そのピーク位置よりｄ００２を算出する。算出方法は学振法（日本学術振興会第１１７委員会が定めた測定法）に従うものであり、具体的には、「炭素繊維」（大谷杉郎著、７３３−７４２頁（１９８６年３月）、近代編集社）などに記載された方法によって測定したものである。
また、波長５１４．５ｎｍのアルゴンレーザーを用いたレーザーラマン分光スペクトルにおけるＲ値は、Ｄバンドの１３６０ｃｍ−１付近に現れるピークの強度をＩＤ、Ｇバンドの１５８０ｃｍ−１付近に現れるピークの強度をＩＧとしたときの比ＩＤ／ＩＧが、０．３以下、好ましくは０．１以下である。 The crystallinity of the carbon powder of the present invention is not particularly limited. However, the higher the crystallinity, the higher the energy density, and thus the higher the crystallinity. Preferably the lattice spacing d 002 is 0.340nm less in X-ray diffraction, more preferably not more than 0.337 nm. The lattice spacing d 002 is obtained by measuring the diffraction peak of the (002) plane of the carbon powder using CuKα ray as the X-ray and using high-purity silicon as a standard substance, and calculating d 002 from the peak position. calculate. The calculation method follows the Japan Science and Technology Act (measurement method defined by the 117th Committee of the Japan Society for the Promotion of Science). Specifically, “Carbon Fiber” (Suguro Otani, pages 733-742 (March 1986) ), Modern Editing Co.) and the like.
The R value in the laser Raman spectrum using an argon laser with a wavelength of 514.5 nm is ID for the peak intensity appearing near 1360 cm −1 in the D band, and IG for the peak intensity appearing near 1580 cm −1 in the G band. The ratio ID / IG is 0.3 or less, preferably 0.1 or less.

本発明の炭素粉末の粒度分布は特に限定されないが、平均粒子径が小さい方が好ましく、好ましくは２０μｍ以下、より好ましくは１５μｍ以下である。しかし、余りに細かすぎると、これを用いて負極材料としたときの分散が困難となり、リチウムイオン二次電池の充放電ロスがあるため、１μｍ以上が好ましく、３μｍ以上がより好ましい。   The particle size distribution of the carbon powder of the present invention is not particularly limited, but a smaller average particle size is preferred, preferably 20 μm or less, more preferably 15 μm or less. However, if it is too fine, it becomes difficult to disperse when used as a negative electrode material, and there is a charge / discharge loss of the lithium ion secondary battery, which is preferably 1 μm or more, and more preferably 3 μm or more.

本発明の炭素粉末は、本質的には黒鉛材料と、炭素材料や炭素前駆体を含む材料が複合化、一体化した構造物であることが好ましい。複合化とは、例えば、黒鉛材料と炭素材料とをメカノケミカル処理し、さらに結合剤を用いて、黒鉛材料の表面に炭素材料を強固に付着させることである。より好ましい炭素粉末は、前記密度比の大きい黒鉛材料（単に黒鉛材料とも称す）と、前記密度比の小さな炭素材料、例えば、メソフェーズ黒鉛材料またはその前駆体（これらを単に炭素材料とも称す）を使用し、これらを互いに偏りなく複合化させたものである。
なお、黒鉛材料と炭素材料であるメソフェーズ小球体の単なる混合物は、本発明のＤＢＰ吸収量と密度比をクリヤーしない。 The carbon powder of the present invention is preferably a structure in which a graphite material and a material containing a carbon material or a carbon precursor are combined and integrated. Compounding means, for example, that a graphite material and a carbon material are mechanochemically treated, and a carbon material is firmly attached to the surface of the graphite material using a binder. More preferable carbon powder uses a graphite material having a high density ratio (also simply referred to as graphite material) and a carbon material having a low density ratio, such as mesophase graphite material or a precursor thereof (these are also simply referred to as carbon materials). However, they are combined without any bias.
In addition, a simple mixture of graphite material and mesophase spherules which are carbon materials does not clear the DBP absorption amount and density ratio of the present invention.

黒鉛材料は、炭素材料に比べ、前記密度比および平均粒子径が大きいが、該密度比は３
〜９、好ましくは４〜８．９、より好ましくは５〜８．８であり、平均粒子径は好ましくは５０μｍ以下、より好ましくは１〜２０μｍである。
黒鉛材料としては、例えば、易黒鉛性炭素材料を３０００℃以上の高温で熱処理した高結晶性の人造黒鉛または天然黒鉛などが挙げられる。これらの形状は鱗片状または鱗状であることが好ましく、あるいはニードル状であってもよい。鱗片状または鱗状であると、得られる炭素粉末の密度比４〜６．５を満足しやすいので特に好ましい。
主原料となる黒鉛材料の結晶性は特に限定されないが、結晶性が高い方がより高エネルギー密度化ができるため、高い方が好ましい。好ましくはＸ線回折における格子面間隔
ｄ００２が０．３４０ｎｍ以下、より好ましくは０．３３７ｎｍ以下である。 The graphite material has a larger density ratio and average particle size than the carbon material, but the density ratio is 3
To 9, preferably 4 to 8.9, more preferably 5 to 8.8, and the average particle size is preferably 50 μm or less, more preferably 1 to 20 μm.
Examples of the graphite material include highly crystalline artificial graphite or natural graphite obtained by heat-treating an easily graphitizable carbon material at a high temperature of 3000 ° C. or higher. These shapes are preferably scaly or scaly, or may be needles. A scale-like or scaly shape is particularly preferred because it easily satisfies the density ratio of the obtained carbon powder of 4 to 6.5.
The crystallinity of the graphite material as the main raw material is not particularly limited, but a higher crystallinity is preferable because higher energy density can be achieved. Preferably the lattice spacing d 002 is 0.340nm less in X-ray diffraction, more preferably not more than 0.337 nm.

炭素材料は、黒鉛材料に比べ、前記密度比および平均粒子径が小さいが、該密度比は１〜５、好ましくは１．３〜４．５、より好ましくは１．５〜４であり、平均粒子径は粒形によらず、好ましくは１０μｍ以下、より好ましくは３μｍ以下である。
炭素材料はメソフェーズ小球体、または、それを粉砕処理した微粉末、さらには、それを３０００℃程度で黒鉛化処理したもの、メソフェーズカーボンファイバーを粉砕した微粉末、サーマルカーボンブラックなどが挙げられる。炭素材料の平均粒子径は、黒鉛材料の長径よりも小さいことが好ましく、黒鉛材料の長径の半分程度の粒子径を持つ塊状の材料であることが好ましい。炭素前駆体はメソフェーズピッチ粉末、または、これを熱処理、酸化または架橋させたものや、フェノール樹脂、フラン樹脂、ポリビニルアルコール樹脂、セルロース樹脂などの樹脂粉末などであり、その平均粒子径は１０μｍ以下、好ましくは３μｍ以下である。 The carbon material has a smaller density ratio and average particle size than the graphite material, but the density ratio is 1 to 5, preferably 1.3 to 4.5, more preferably 1.5 to 4. The particle diameter is preferably 10 μm or less, more preferably 3 μm or less, regardless of the particle shape.
Examples of the carbon material include mesophase spherules, fine powder obtained by pulverizing the mesophase, and those obtained by graphitizing the mesophase carbon fiber, fine powder obtained by pulverizing mesophase carbon fiber, and thermal carbon black. The average particle diameter of the carbon material is preferably smaller than the long diameter of the graphite material, and is preferably a massive material having a particle diameter about half the long diameter of the graphite material. The carbon precursor is a mesophase pitch powder, or a heat-treated, oxidized or crosslinked resin powder such as a phenol resin, a furan resin, a polyvinyl alcohol resin, or a cellulose resin, and the average particle diameter thereof is 10 μm or less. Preferably it is 3 micrometers or less.

黒鉛材料と炭素材料の組合せとしては、例えば、高結晶性の鱗片状天然黒鉛と微粉砕されたメソフェーズ黒鉛粒子との組合せ、または、高結晶性の鱗片状人造黒鉛とカーボンブラックの中でも平均粒子径が大きく、二次粒子を形成することが少ないサーマルカーボンブラックとの組合わせなどが好適である。   Examples of the combination of the graphite material and the carbon material include, for example, a combination of highly crystalline scaly natural graphite and finely pulverized mesophase graphite particles, or an average particle size among highly crystalline scaly artificial graphite and carbon black. A combination with thermal carbon black that has a large particle size and little secondary particles is preferable.

黒鉛材料と炭素材料の混合比率については、粒子径、形状などによって異なるので、一概には言えないが、炭素材料の割合は、黒鉛材料の全表面に炭素材料が単層で付着した場合よりも少ない方が好ましい。炭素材料の粒子径が小さければそれだけ同じ質量で粒子数が多くなるので、質量では一概に言えないが、通常、黒鉛材料１００質量部に対し、炭素材料が１質量部以上、５０質量部までが好ましい範囲である。   The mixing ratio of the graphite material and the carbon material varies depending on the particle diameter, shape, etc., so it cannot be generally stated, but the ratio of the carbon material is more than the case where the carbon material adheres as a single layer on the entire surface of the graphite material. Less is preferable. If the particle size of the carbon material is small, the number of particles increases with the same mass. Therefore, the mass of the carbon material is usually 1 to 50 parts by mass with respect to 100 parts by mass of the graphite material. This is a preferred range.

〔炭素材料の製造〕
本発明の炭素粉末は、例えば、以下の方法によって製造することができる。
プレス圧縮性が高く（密度比が大きい）、平均粒子径の大きい黒鉛材料と、密度比がより小さく、平均粒子径がより小さい塊状の微小黒鉛または炭素粒子、好ましくはメソフェーズ小球体を粉砕した炭素材料とに、充分に剪断力をかけてメカノケミカル処理した後、結合剤を介して気相または液相にて炭素材料を黒鉛材料の表面に付着させ、炭素材料を固定し複合化する。さらに、熱処理を行って、炭素材料を炭化または黒鉛化することによって、本発明の炭素粉末を得ることができる。 [Manufacture of carbon materials]
The carbon powder of the present invention can be produced, for example, by the following method.
Graphite material with high press-compressibility (high density ratio) and large average particle diameter, and agglomerated fine graphite or carbon particles with a smaller density ratio and smaller average particle diameter, preferably carbon obtained by pulverizing mesophase spherules After a mechanochemical treatment is applied to the material with sufficient shearing force, the carbon material is adhered to the surface of the graphite material in a gas phase or a liquid phase via a binder, and the carbon material is fixed and combined. Furthermore, the carbon powder of this invention can be obtained by performing heat processing and carbonizing or graphitizing a carbon material.

メカノケミカル処理は、黒鉛材料と炭素材料に圧縮力と剪断力を同時にかける処理を言う。剪断力や圧縮力は通常一般の攪拌力よりも大きいが、これらの機械的応力は、黒鉛材料と炭素材料の表面に懸けることが好ましく、黒鉛材料と炭素材料の骨格を破壊しないことが好ましい。該骨格が破壊されると、負極材料として使用したときに、不可逆容量の増大を招く傾向がある。剪断力や圧縮力は、一般的にはメカノケミカル処理による黒鉛材料と炭素材料の平均粒子径の低下率を２０％以下に抑える程度であることが好ましい。   Mechanochemical treatment refers to a treatment in which a compressive force and a shear force are simultaneously applied to a graphite material and a carbon material. Although the shearing force and compressive force are usually larger than general stirring force, these mechanical stresses are preferably applied to the surfaces of the graphite material and the carbon material, and preferably do not destroy the skeleton of the graphite material and the carbon material. When the skeleton is destroyed, when used as a negative electrode material, the irreversible capacity tends to increase. In general, the shearing force and the compressive force are preferably such that the reduction rate of the average particle diameter of the graphite material and the carbon material by mechanochemical treatment is suppressed to 20% or less.

メカノケミカル処理装置は、例えば、黒鉛材料と炭素材料に剪断力と圧縮力を同時にかけることができる装置であれば、装置の種類、構造は特に限定されない。例えば、加圧ニーダー、二本ロールなどの混練機、回転ボールミル、「ハイブリダイゼーションシステム」（奈良機械製作所製）などの高速衝撃式乾式複合化装置、「メカノマイクロシステム」（奈良機械製作所製）、「メカノフュージョシステム」（ホソカワミクロン社製）などの圧縮剪断式乾式粉体複合化装置などを使用することができる。   As long as the mechanochemical treatment apparatus is an apparatus that can simultaneously apply a shearing force and a compressive force to a graphite material and a carbon material, the type and structure of the device are not particularly limited. For example, a kneader such as a pressure kneader, two rolls, a rotating ball mill, a high-speed impact dry compounding device such as a “hybridization system” (manufactured by Nara Machinery Co., Ltd.), a “mechanomicro system” (manufactured by Nara Machinery Co., Ltd.), A compression shear type dry powder compounding device such as “Mechano-Fusion System” (manufactured by Hosokawa Micron) can be used.

中でも、回転速度差を利用して剪断力と圧縮力を同時にかける装置が好ましい。具体的には、回転するドラム（回転ローター）と、該ドラムと回転速度の異なる内部部材（インナーピース）と、黒鉛材料と炭素材料の循環機構（例：循環用ブレード）とを有する装置（「メカノフュージョンシステム」）を用い、回転ドラムと内部部材との間に供給された黒鉛材料と炭素材料に遠心力を付与しながら、内部部材により回転ドラムとの速度差に起因する剪断力と圧縮力とを同時に繰返しかけることによりメカノケミカル処理することが好ましい。
また、固定ドラム（ステーター）と、高速回転する回転ローターの間に黒鉛粒子と微小黒鉛粒子を通すことで固定ドラムと回転ローターとの速度差に起因する剪断力と圧縮力を黒鉛粒子と微小黒鉛粒子に同時にかける装置（「ハイブリダイゼーションシステム」）も好ましい。 Among them, an apparatus that applies a shearing force and a compressing force simultaneously using a rotational speed difference is preferable. Specifically, an apparatus ("a rotating rotor), an internal member (inner piece) having a rotational speed different from that of the drum, and a circulation mechanism (eg, a circulation blade) of graphite material and carbon material (" circulation blade "). Using a mechano-fusion system "), while applying centrifugal force to the graphite material and carbon material supplied between the rotating drum and the internal member, shear force and compressive force due to the speed difference from the rotating drum by the internal member It is preferable to carry out mechanochemical treatment by repeating the above simultaneously.
In addition, by passing graphite particles and fine graphite particles between a fixed drum (stator) and a rotating rotor rotating at high speed, the shear force and compressive force due to the speed difference between the fixed drum and rotating rotor can be reduced. Also preferred are devices that simultaneously apply particles ("hybridization system").

メカノケミカル処理の条件は、使用する装置によっても異なり一概に言えないが、例えば、「メカノフュージョンシステム」の場合には、回転ドラムと内部部材との周速度差が５〜５０m/sec、両者間の距離が１〜１００mm、処理時間が３〜９０minであることが好ましい。また、「ハイブリダイゼーションシステム」の場合には、固定ドラムと回転ローターとの周速度差が１０〜１００m/sec、処理時間が３０sec〜１０minであることが好ましい。   The conditions of mechanochemical treatment differ depending on the equipment used, and cannot be generally stated. For example, in the case of the “mechanofusion system”, the peripheral speed difference between the rotating drum and the internal member is 5 to 50 m / sec. The distance is preferably 1 to 100 mm and the processing time is 3 to 90 min. In the case of the “hybridization system”, the peripheral speed difference between the stationary drum and the rotating rotor is preferably 10 to 100 m / sec, and the processing time is preferably 30 sec to 10 min.

次に、メカノケミカル処理品に、結合剤を用いて、黒鉛材料と炭素材料を互いに強固に付着させ、炭素粉末を得る。例えば、メカノケミカル処理品１００質量部に対し０．５〜２０質量部の結合剤を加え、要すれば、加熱して結合剤を流動化して、付着させる方法が採用される。黒鉛材料と炭素材料とが結合し、複合化できればよいので、結合剤層の層厚は一概に規定できない。
結合剤には、易黒鉛化性または難黒鉛化性の前駆体を用いることが好ましい。具体的には、石油系ピッチ、石炭系ピッチ、ピッチを酸化などによって変性させたもの、樹脂を分解して生成するピッチなどが使用できる。
また、気相または液相で有機物を熱分解させ、分解生成物の重合成分が粒子同士の接触部に堆積することでも同様な効果が得られる。例えば、ベンゼン、メタン、エチレン、脂肪族アルコールなどを気相で熱分解させ、メカノケミカル処理品に接触させてもよい。または、熱分解後に残炭成分を残す樹脂を液相でメカノケミカル処理品に接触させた後、熱処理（例えば、非酸化性雰囲気中で６００〜１２００℃で加熱）を行い、樹脂を分解させてもよい。この場合、樹脂としては、フェノール樹脂、フラン樹脂、ポリビニルアルコール樹脂、セルロース系樹脂などが好ましく用いられる。
結合剤による複合化後、未複合化物などを除去し、さらに生成物粗大粒子や微小粒子を分離し、必要ならば、平均粒子径が一定範囲の炭素粉末を得ることができる。 Next, the graphite material and the carbon material are firmly adhered to the mechanochemically processed product using a binder to obtain a carbon powder. For example, a method in which 0.5 to 20 parts by mass of a binder is added to 100 parts by mass of a mechanochemically processed product, and if necessary, the binder is fluidized and adhered is employed. Since the graphite material and the carbon material may be combined and combined, the layer thickness of the binder layer cannot be specified unconditionally.
For the binder, it is preferable to use a graphitizable or non-graphitizable precursor. Specifically, petroleum pitch, coal pitch, pitch modified by oxidation, pitch generated by decomposing resin, and the like can be used.
Further, the same effect can be obtained by thermally decomposing an organic substance in a gas phase or a liquid phase and depositing a polymerization component of the decomposition product on a contact portion between particles. For example, benzene, methane, ethylene, aliphatic alcohol, etc. may be thermally decomposed in the gas phase and contacted with the mechanochemically treated product. Or after making resin which leaves a residual carbon component after thermal decomposition contact with a mechanochemical treatment product in a liquid phase, heat treatment (for example, heating at 600 to 1200 ° C. in a non-oxidizing atmosphere) is performed to decompose the resin. Also good. In this case, as the resin, a phenol resin, a furan resin, a polyvinyl alcohol resin, a cellulose resin, or the like is preferably used.
After complexing with the binder, uncomplexed materials and the like are removed, and the product coarse particles and fine particles are separated, and if necessary, carbon powder having an average particle diameter in a certain range can be obtained.

［負極］
本発明の負極は、−定のＤＢＰ吸収量と密度比を有する炭素粉末を含む負極材料を用いて作製する。該炭素粉末を単独で用いても高密度域での電池特性が良好な負極を得ることができるが、通常使用されている導電材、改質材、添加剤などを混合してもよい。これらの添加量は、添加する材料によって最適量が変わるため一概には言えないが、該炭素粉末１００質量％に対し０．１〜１０質量％である。
また、他の負極活物質として人造黒鉛、天然黒鉛、天然黒鉛または人造黒鉛の造粒物、メソフェーズ小球体の黒鉛化物、バルクメソフェーズ黒鉛、メソフェーズピッチ炭素繊維の黒鉛化物、ナノ黒鉛繊維などを、本発明の効果を損なわない範囲で該炭素粉末に混合することができる。 [Negative electrode]
The negative electrode of the present invention is produced using a negative electrode material containing carbon powder having a constant DBP absorption amount and a density ratio. Even if the carbon powder is used alone, a negative electrode having good battery characteristics in a high density region can be obtained. However, conductive materials, modifiers, additives and the like which are usually used may be mixed. These addition amounts cannot be generally specified because the optimum amount varies depending on the material to be added, but are 0.1 to 10% by mass with respect to 100% by mass of the carbon powder.
Other negative electrode active materials include artificial graphite, natural graphite, natural graphite or granulated granulated graphite, mesophase microsphere graphitized material, bulk mesophase graphite, mesophase pitch carbon fiber graphitized material, nano graphite fiber, etc. It can mix with this carbon powder in the range which does not impair the effect of invention.

本発明の炭素粉末を含む負極材料を用いる負極の作製は、該炭素粉末の性能を充分に引き出し、かつ該炭素粉末に対する賦型性が高く、化学的、電気化学的に安定な負極を得ることができる成形方法であれば何ら制限されず、通常の成形方法に準じて行うことができる。例えば、該炭素粉末をポリエチレン、ポリビニルアルコールなどの樹脂粉末と乾式混合し、金型内でホットプレス成形して負極を製造することもできる。層厚は１０〜２００μｍ、好ましくは２０〜２００μｍである。
なお、本発明の炭素粉末を含む負極材料は、一定のプレス圧縮性を有するために、プレス時にも、炭素粉末の割れが少なく、負極材料に用いた時にも、充放電効率が高い。 The production of a negative electrode using a negative electrode material containing the carbon powder of the present invention is to obtain a negative electrode that is sufficiently chemically and electrochemically drawn out of the performance of the carbon powder and that is highly moldable to the carbon powder. The molding method is not particularly limited as long as it can be performed, and can be performed according to a normal molding method. For example, the carbon powder can be dry-mixed with resin powders such as polyethylene and polyvinyl alcohol, and hot press molded in a mold to produce a negative electrode. The layer thickness is 10 to 200 μm, preferably 20 to 200 μm.
In addition, since the negative electrode material containing the carbon powder of this invention has fixed press compressibility, there are few cracks of a carbon powder also at the time of a press, and when it uses for a negative electrode material, charging / discharging efficiency is high.

また、本発明の炭素粉末に結着剤を加えて調製した負極合剤を用いて負極を作製することができる。負極合剤の調製は、例えば、本発明の炭素粉末と、他の炭素材料を分級等によって適当な粒径に調整し、結着剤と混合することによって実施される。本発明の炭素粉末を用いることにより、有機溶媒に溶解および／または分散する有機溶媒系結着剤はもちろんのこと、水溶性および／または水分散性の水系結着剤を用いても優れた充放電特性を発現する負極を得ることができる。   Moreover, a negative electrode can be produced using a negative electrode mixture prepared by adding a binder to the carbon powder of the present invention. The negative electrode mixture is prepared, for example, by adjusting the carbon powder of the present invention and another carbon material to an appropriate particle size by classification or the like and mixing with a binder. By using the carbon powder of the present invention, not only an organic solvent-based binder that dissolves and / or disperses in an organic solvent, but also a water-soluble and / or water-dispersible aqueous binder can be used. A negative electrode that exhibits discharge characteristics can be obtained.

結着剤としては、電解質に対して化学的安定性、電気化学的安定性を有するものが好ましく、例えば、ポリフッ化ビニリデン、ポリテトラフルオロエチレンなどのフッ素系樹脂、ポリエチレン、ポリビニルアルコール、さらにはカルボキシメチルセルロース、スチレンブタジエンゴムなどが用いられる。これらを併用することもできる。中でも、本発明の目的を達成し、効果を最大限に活かす上で、カルボキシメチルセルロース（水溶性）、ポリビニルアルコール（水溶性）、スチレンブタジエンゴム（水分散性）などの水系結着剤を用いることが特に好ましい。
結着剤は、通常、負極合剤の全量中０．５〜２０質量％の割合で使用されることが好ましい。 As the binder, those having chemical stability and electrochemical stability with respect to the electrolyte are preferable. For example, fluorine resins such as polyvinylidene fluoride and polytetrafluoroethylene, polyethylene, polyvinyl alcohol, and carboxy. Methyl cellulose, styrene butadiene rubber or the like is used. These can also be used together. Among them, in order to achieve the object of the present invention and make the most of the effect, an aqueous binder such as carboxymethyl cellulose (water-soluble), polyvinyl alcohol (water-soluble), styrene butadiene rubber (water-dispersible) is used. Is particularly preferred.
In general, the binder is preferably used at a ratio of 0.5 to 20% by mass in the total amount of the negative electrode mixture.

例えば、本発明の炭素粉末と、ポリフッ化ビニリデン、ポリテトラフルオロエチレンなどのフッ素系樹脂粉末などを、Ｎ−メチルピロリドン、ジメチルホルムアミドなどの溶媒と混合してスラリーとする。中でも、溶媒の乾燥除去における安全面、環境面への影響に配慮して、水などを溶媒として、カルボキシメチルセルロース、スチレンブタジエンゴムなどを溶解または分散させてなる水系スラリーとすることが好ましい。該スラリーを、通常、集電材の片面もしくは両面に塗布して負極合剤層を形成する。   For example, the carbon powder of the present invention and a fluorine resin powder such as polyvinylidene fluoride and polytetrafluoroethylene are mixed with a solvent such as N-methylpyrrolidone and dimethylformamide to form a slurry. Among these, in consideration of the influence on the safety and environmental aspects in drying and removing the solvent, it is preferable to use an aqueous slurry obtained by dissolving or dispersing carboxymethyl cellulose, styrene butadiene rubber or the like using water as a solvent. The slurry is usually applied to one side or both sides of a current collector to form a negative electrode mixture layer.

また負極合剤を溶媒に分散させ、ペースト状にした後、集電材に塗布、乾燥すれば、集電材に均−かつ強固に接着した負極合剤層が形成される。溶媒は前記スラリーの調製に使用される通常の溶媒で差し支えない。ペーストは、公知の攪拌機、混合機、混練機、ニーダーなどを用いて混合することにより調製されるが、例えば、翼式ホモミキサーで３００〜３０００ｒｐｍ程度で攪拌することにより調製される。
本発明による負極材料と結着剤を混合してなる負極合剤を集電材に塗布する際の層厚は１０〜２００μｍ、好ましくは２０〜２００μｍである。
負極合剤層を形成した後、プレス加工などの圧着を行うと、負極合剤層と集電材との接着強度をさらに高めることができる。 In addition, if the negative electrode mixture is dispersed in a solvent and made into a paste, and then applied to the current collector and dried, a negative electrode mixture layer uniformly and firmly adhered to the current collector is formed. The solvent may be a conventional solvent used for preparing the slurry. The paste is prepared by mixing using a known stirrer, mixer, kneader, kneader, or the like. For example, the paste is prepared by stirring at about 300 to 3000 rpm with a wing-type homomixer.
The layer thickness when applying the negative electrode mixture obtained by mixing the negative electrode material and the binder according to the present invention to the current collector is 10 to 200 μm, preferably 20 to 200 μm.
When the negative electrode mixture layer is formed and then pressure bonding such as press working is performed, the adhesive strength between the negative electrode mixture layer and the current collector can be further increased.

負極に用いる集電材の形状は、特に限定されないが、箔状、またはメッシュ、エキスバンドメタルなどの網状のものなどが用いられる。集電材としては、例えば銅、ステンレス、ニッケルなどを挙げることができる。集電材の厚みは、箔状の場合、５〜２０μｍであることが好ましい。   The shape of the current collector used for the negative electrode is not particularly limited, but a foil or a net-like material such as a mesh or an extended metal is used. Examples of the current collector include copper, stainless steel, and nickel. In the case of a foil, the thickness of the current collector is preferably 5 to 20 μm.

本発明の炭素粉末を負極材料に用いた負極を含むリチウムイオン二次電池が、優れた充放電特性を発現する理由は、該炭素粉末、結着剤などを用いて負極合剤を調製する時に、結着剤が炭素粉末の表面に薄く分散するとともに、確保された空隙に確実に浸透し、アンカー効果で炭素粉末同士を強固に結びつける結果、充放電を繰返しても炭素粉末同士、さらには結着剤を介して炭素粉末と集電材との強固な密着が維持され、導電性、イオン伝導性、電解液浸透性などを阻害することがないためと考えられる。さらに、負極内では、空隙内に電解液を取り込み、炭素粉末の周りに保持する効果も合わせ持つからではないかと推察される。   The reason why a lithium ion secondary battery including a negative electrode using the carbon powder of the present invention as a negative electrode material exhibits excellent charge / discharge characteristics is that when preparing a negative electrode mixture using the carbon powder, a binder or the like. As a result of the binder being thinly dispersed on the surface of the carbon powder, it surely penetrates into the secured voids and firmly bonds the carbon powders with the anchor effect. It is considered that the strong adhesion between the carbon powder and the current collector is maintained through the adhesive and does not hinder the conductivity, ion conductivity, electrolyte permeability, and the like. Furthermore, in the negative electrode, it is presumed that the electrolyte solution is taken into the gap and held around the carbon powder.

［正極］
正極活物質としては、充分量のリチウムをドープ／脱ドープし得るものを選択することが好ましい。正極活物質としては、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（Ｖ２Ｏ５、Ｖ６Ｏ１３、Ｖ２Ｏ４、Ｖ３Ｏ８など）およびそのリチウム化合物、一般式ＭｘＭｏ６Ｓ８−ｙ「（式中Ｘは０≦Ｘ≦４、Ｙは０≦Ｙ≦１の範囲の数であり、Ｍは遷移金属などの金属を表す）で表されるシェフレル相化合物、活性炭、活性炭素繊維などを用いることができる。 [Positive electrode]
As the positive electrode active material, it is preferable to select a material capable of doping / dedoping a sufficient amount of lithium. Examples of the positive electrode active material include lithium-containing transition metal oxides, transition metal chalcogenides, vanadium oxides (V 2 O 5 , V 6 O 13 , V 2 O 4 , V 3 O 8 and the like) and lithium compounds thereof, general formulas M x Mo 6 S 8-y (where X is a number in a range of 0 ≦ X ≦ 4, Y is a number in a range of 0 ≦ Y ≦ 1, and M represents a metal such as a transition metal). A compound, activated carbon, activated carbon fiber, etc. can be used.

前記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。リチウム含有遷移金属酸化物は、具体的には、ＬｉＭ（１）１−ｐＭ（２）ｐＯ２（式中Ｐは０≦Ｐ≦１の範囲の数であり、Ｍ（１）、Ｍ（２）は少なくとも一種の遷移金属元素からなる。）またはＬｉＭ（１）２−ＱＭ（２）ＱＯ４（式中Ｑは０≦Ｑ≦１の範囲の数であり、Ｍ（１）、Ｍ（２）は少なくとも一種の遷移金属元素からなる。）で示される。
前記において、Ｍで示される遷移金属元素としては、Ｃｏ、Ｎｉ、Ｍｎ、Ｃｒ、Ｔｉ、Ｖ、Ｆｅ、Ｚｎ、Ａｌ、Ｉｎ、Ｓｎなどが挙げられ、好ましくはＣｏ、Ｎｉ、Ｆｅ、Ｍｎ、Ｔｉ、Ｃｒ、Ｖ、Ａｌが挙げられる。 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. Specifically, the lithium-containing transition metal oxide is LiM (1) 1-p M (2) p O 2 (wherein P is a number in the range of 0 ≦ P ≦ 1, M (1), M (2) comprises at least one transition metal element.) Or LiM (1) 2-Q M (2) Q O 4 (wherein Q is a number in the range of 0 ≦ Q ≦ 1, M (1) , M (2) is composed of at least one transition metal element).
In the above, examples of the transition metal element represented by M include Co, Ni, Mn, Cr, Ti, V, Fe, Zn, Al, In, and Sn, and preferably Co, Ni, Fe, Mn, and Ti. , Cr, V, and Al.

リチウム含有遷移金属酸化物としては、より具体的に、ＬｉＣｏＯ２、ＬｉｐＮｉＱＭ１−ＱＯ２（ＭはＮｉを除く前記遷移金属元素であり、好ましくはＣｏ、Ｆｅ、Ｍｎ、Ｔｉ、Ｃｒ、Ｖ、Ａｌから選ばれる少なくとも−種、０．０５≦ｐ≦１．１０、０．５≦ｑ≦１．０である。）で示されるリチウム複合酸化物、ＬｉＮｉＯ２、ＬｉＭｎＯ２、ＬｉＭｎ２Ｏ４などが挙げられる。 Examples of the lithium-containing transition metal oxide, more specifically, LiCoO 2, Li p Ni Q M 1-Q O 2 (M is said transition metal elements excluding Ni, preferably Co, Fe, Mn, Ti, Lithium composite oxide, LiNiO 2 , LiMnO 2 , LiMn represented by (at least-selected from Cr, V, Al, 0.05 ≦ p ≦ 1.10, 0.5 ≦ q ≦ 1.0) 2 O 4 or the like.

前記のようなリチウム含有遷移金属酸化物は、例えば、リチウム、遷移金属の酸化物または塩類を出発原料とし、これら出発原料を所望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。なお出発原料は酸化物または塩類に限定されず、水酸化物などでもよい。
本発明では、正極活性物質は、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、正極材料に炭酸リチウムなどの炭酸アルカリ塩を添加することもできる。 The lithium-containing transition metal oxide as described above includes, for example, lithium, transition metal oxides or salts as starting materials, these starting materials are mixed according to a desired composition, and are heated at 600 to 1000 ° C. in an oxygen atmosphere. It can be obtained by firing at a temperature. The starting material is not limited to oxides or salts but may be hydroxides.
In the present invention, the positive electrode active material may be used alone or in combination of two or more. For example, an alkali carbonate such as lithium carbonate can be added to the positive electrode material.

このような正極材料によって正極を形成するには、例えば正極材料と結着剤および電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材の両面に塗布することで正極合剤層を形成する。結着剤としては、負極で例示したものがいずれも使用可能である。導電剤としては、例えば炭素材料、黒鉛やカーボンブラックが用いられる。   In order to form a positive electrode with such a positive electrode material, for example, a positive electrode mixture comprising a positive electrode material, a binder, and a conductive agent for imparting conductivity to the electrode is applied to both surfaces of the current collector. Form a layer. As the binder, any of those exemplified for the negative electrode can be used. As the conductive agent, for example, a carbon material, graphite or carbon black is used.

集電材の形状は特に限定されず、箱状、またはメッシュ、エキスバンドメタルなどの網状などのものが用いられる。集電材の基板としては、アルミニウム、ステンレス、ニッケルなどを挙げることができる。その厚さは１０〜４０μｍが好適である。
また正極の場合も負極と同様に、正極合剤を溶剤中に分散させることでペースト状にし、このペースト状の正極合剤を集電材に塗布、乾燥することによっ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構わない。これにより正極合剤層が均一かつ強固に集電材に接着される。 The shape of the current collector is not particularly limited, and a box shape or a mesh shape such as a mesh or an extended metal is used. Examples of the current collector substrate include aluminum, stainless steel, and nickel. The thickness is preferably 10 to 40 μm.
Also in the case of the positive electrode, like the negative electrode, the positive electrode mixture is dispersed in a solvent to form a paste, and the paste-like positive electrode mixture is applied to a current collector and dried to form a positive electrode mixture layer. Alternatively, after the positive electrode mixture layer is formed, 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.

［電解質］
本発明に用いられる電解質としては通常の非水電解液に使用されている電解質塩を用いることができ、例えば、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＡｓＦ６、ＬｉＣｌＯ４、ＬｉＢ（Ｃ６Ｈ５）４、ＬｉＣｉ、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などのリチウム塩などを用いることができる。特にＬｉＰＦ６、ＬｉＢＦ４が酸化安定性の点から好ましく用いられる。
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。 [Electrolytes]
As the electrolyte used for the present invention can be used an electrolyte salt used in the conventional non-aqueous electrolyte solution, for example, LiPF 6, LiBF 4, LiAsF 6, LiClO 4, LiB (C 6 H 5) 4, LiCi, 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, LiSiF such 6 A lithium salt or the like can be used. In particular, LiPF 6 and LiBF 4 are preferably used from the viewpoint of oxidation stability.
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.

前記非水電解質は、液系の非水電解液としてもよいし、固体電解質あるいはゲル電解質など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、非水電解質電池は、高分子固体電解質電池、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 nonaqueous electrolyte may be a liquid nonaqueous 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 battery or a polymer gel electrolyte battery. The

ジメチルカーボネート、ジエチルカーボネート、１，１一または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−プチロラクトン、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、スルホラン、メチルスルホラン、アセトニトリル、クロロニトリル、プロピオニトリル、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エン、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を用いることができる。   Dimethyl carbonate, diethyl carbonate, 1,1 mono or 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, γ-ptyrolactone, 1,3-dioxolane, 4-methyl-1,3 -Dioxolane, anisole, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, chloronitrile, propionitrile, trimethyl borate, tetramethyl silicate, nitromethane, dimethylformamide, N-methylpyrrolidone, ethyl acetate, trimethyl orthoformate, nitrobenzene , Aprotic such as benzoyl chloride, benzoyl bromide, tetrahydrothiophene, dimethyl sulfoxide, 3-methyl-2-oxazolidone, ethylene glycol, dimethyl sulfite Machine solvent can be used.

非水電解質を高分子固体電解質、高分子ゲル電解質などの高分子電解質とする場合には、可塑剤（非水電解液）でゲル化されたマトリックスの高分子を含むが、このマトリックス高分子としては、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樹脂、ポリメタクリレート系、ポリアクリレート系、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樹脂などを単独、もしくは混合して用いることができる。
これらの中で、酸化還元安定性の観点などから、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ビレン共重合体などのフッ素系樹脂を用いることが望ましい。 When the non-aqueous electrolyte is a polymer electrolyte such as a polymer solid electrolyte or a polymer gel electrolyte, it contains a matrix polymer gelled with a plasticizer (non-aqueous electrolyte). Is an ether-based resin such as polyethylene oxide or its cross-linked product, a fluorine-based resin such as polymethacrylate-based, polyacrylate-based, polyvinylidene fluoride or vinylidene fluoride-hexafluoropropylene copolymer, or a mixture thereof. Can be used.
Among these, from the viewpoint of oxidation-reduction stability, it is desirable to use a fluorine-based resin such as polyvinylidene fluoride or vinylidene fluoride-hexafluoropropylene copolymer.

これら高分子固体電解質、高分子ゲル電解質に含有される可塑剤を構成する電解質塩や非水溶媒としては、前述のものがいずれも使用可能である。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。
このような高分子電解質の製造方法は特に制限されないが、例えば、マトリックスを形成する高分子、リチウム塩および溶媒を混合し、加熱して溶融する方法、適当な有機溶剤に高分子、リチウム塩および溶媒を溶解させた後、有機溶剤を蒸発させる方法、ならびに高分子電解質の原料となる重合性モノマー、リチウム塩および溶媒を混合し、それに紫外線、電子線または分子線などを照射して重合させ高分子電解質を製造する方法などを挙げることができる。
また、前記固体電解質中の溶媒の混合割合が１０〜９０質量％であると、導電率が高く、かつ機械的強度が高く、成膜しやすいので好ましく、より好ましくは３０〜８０質量％である。 As the electrolyte salt and non-aqueous solvent constituting the plasticizer contained in these polymer solid electrolyte and polymer gel electrolyte, any of those described above can be used. In the case of a polymer gel electrolyte, the electrolyte salt concentration in the non-aqueous electrolyte 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 such a polymer electrolyte is not particularly limited. For example, a method of mixing a polymer that forms a matrix, a lithium salt, and a solvent, and heating and melting the polymer, a polymer, a lithium salt, and a suitable organic solvent After dissolving the solvent, the method of evaporating the organic solvent, and the polymerizable monomer, lithium salt, and solvent that are the raw materials for the polymer electrolyte are mixed, and the mixture is polymerized by irradiation with ultraviolet rays, electron beams, or molecular beams. Examples thereof include a method for producing a molecular electrolyte.
Moreover, it is preferable that the mixing ratio of the solvent in the solid electrolyte is 10 to 90% by mass because the electrical conductivity is high and the mechanical strength is high and the film is easily formed, and more preferably 30 to 80% by mass. .

［リチウムイオン二次電池］
リチウムイオン二次電池は、通常、負極、正極および非水電解質を主たる電池構成要素とし、正極、負極はそれぞれリチウムイオンの担持体からなり、充放電過程におけるリチウムイオンの出入は層間で行われる．そして充電時にはリチウムイオンが負極中にドープし、放電時には負極から脱ドープする電池機構を横成する。
本発明のリチウムイオン二次電池は、負極材料以外は特に限定されず、他の電池構成要素については一般的なリチウムイオン二次電池の要素に準じる。 [Lithium ion secondary battery]
In general, a lithium ion secondary battery includes a negative electrode, a positive electrode, and a nonaqueous electrolyte as main battery components, and the positive electrode and the negative electrode are each made of a lithium ion carrier, and lithium ions are input and output in the charge / discharge process between layers. Then, a battery mechanism in which lithium ions are doped into the negative electrode during charging and dedope from the negative electrode during discharging is established.
The lithium ion secondary battery of the present invention is not particularly limited except for the negative electrode material, and other battery components conform to the elements of a general lithium ion secondary battery.

本発明のリチウムイオン二次電池に使用するセパレータは、特に限定されるものではないが、例えば織布、不繊布、合成樹脂製微多孔膜などが挙げられる。特に合成樹脂製微多孔膜が好適に用いられるが、その中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などである。   The separator used in the lithium ion secondary battery of the present invention is not particularly limited, and examples thereof include woven cloth, non-woven cloth, and a synthetic resin microporous film. In particular, a synthetic resin microporous membrane is preferably used. Among these, a polyolefin microporous membrane is preferable in terms of thickness, membrane strength, and membrane resistance. Specifically, it is a microporous film made of polyethylene and polypropylene, or a microporous film in which these are combined.

本発明のリチウムイオン二次電池において、ゲル電解質を用いることも可能である。ゲ
ル電解質二次電池は、負極、正極およびゲル電解質を、例えば負極、ゲル電解質、正極の順で積層し、電池外装材内に収容することで構成される。なお、さらに負極と正極の外側にゲル電解質を配するようにしてもよい。 In the lithium ion secondary battery of the present invention, a gel electrolyte can also be used. The gel electrolyte secondary battery is configured by laminating a negative electrode, a positive electrode, and a gel electrolyte in the order of, for example, a negative electrode, a gel electrolyte, and a positive electrode, and housing the battery in a battery exterior material. Further, a gel electrolyte may be disposed outside the negative electrode and the positive electrode.

本発明に係るリチウムイオン二次電池の構造は任意であり、その形状、形態について特に限定されるものではなく、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の上昇を感知して電流を遮断させる手段を備えたものであることが好ましい。アルミラミネートフィルムなどに封入した構造とすることもできる。 The structure of the lithium ion secondary battery according to the present invention is arbitrary, and the shape and form thereof are not particularly limited, and can be arbitrarily selected from a cylindrical shape, a square shape, a coin shape, a button shape, and the like. it can.
In order to obtain a sealed nonaqueous electrolyte battery with higher safety, it is preferable to include a means for detecting an increase in the internal pressure of the battery and shutting off the current when there is an abnormality such as overcharging. A structure encapsulated in an aluminum laminate film or the like can also be used.

以下に、本発明を実施例および比較例によって具体的に説明する。本発明はこれらの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、炭素粉末を図１に示すような構造の評価用のボタン型電池を作製して評価した。実電池は、本発明の概念に基き、公知の方法に準じて作製することができる。   Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited to these examples. Further, in the following examples and comparative examples, carbon powder was evaluated by producing a button type battery for evaluation having a structure as shown in FIG. The actual battery can be manufactured according to a known method based on the concept of the present invention.

炭素粉末の粒子の物性は下記のように測定した。
［平均粒子径］
平均粒子径Ｄ５０は、レーザー回折式粒度分布計（セイシン企業社製、ＬＭＳ−３０）により粒度分布の累積度数が体積百分率で５０％となる粒子径とした。
［格子面間隔］
格子面間隔ｄ００２は、前記したように、Ｘ線回折装置（理学電機社製、「ロータフレックス」ＲＵ−３００）において、Ｘ線としてＣｕＫα線を用い、高純度シリコンを標準物質とするＸ線回折法により求めた。
［ラマン分光によるＲ値］
Ｒ値は、レーザーラマン分光分析装置（日本分光社製，ＮＲ−１８００）を用い、励起光は５１４．５ｎｍのアルゴンイオンレーザー、照射面積は５０μｍφで分析し、Ｄバンドの１３６０ｃｍ−１付近に現れるピークの強度をＩＤ、Ｇバンドの１５８０ｃｍ−１付近に現れるピークの強度をＩＧとしたときの比ＩＤ／ＩＧである。
［比表面積］
比表面積は、「モノソーブ」ＭＳ２０（ユアサアイオニクス社製）を用いて測定した、窒素ガス吸着によるＢＥＴ比表面積である。 The physical properties of the carbon powder particles were measured as follows.
[Average particle size]
The average particle diameter D50 was a particle diameter at which the cumulative frequency of particle size distribution was 50% by volume using a laser diffraction particle size distribution analyzer (manufactured by Seishin Enterprise Co., Ltd., LMS-30).
[Lattice spacing]
As described above, the lattice spacing d 002 is X-rays using CuKα rays as X-rays and high-purity silicon as a standard material in an X-ray diffractometer (manufactured by Rigaku Corporation, “Rotorflex” RU-300). Obtained by the diffraction method.
[R value by Raman spectroscopy]
The R value is analyzed using a laser Raman spectrometer (NR-1800, manufactured by JASCO Corporation), the excitation light is 514.5 nm argon ion laser, the irradiation area is 50 μmφ, and appears near 1360 cm −1 of the D band. The ratio is ID / IG, where ID is the peak intensity and IG is the peak intensity appearing near 1580 cm −1 of the G band.
[Specific surface area]
The specific surface area is a BET specific surface area by nitrogen gas adsorption measured using “Monosorb” MS20 (manufactured by Yuasa Ionics).

［ＤＢＰ吸収量］
ＪＩＳ Ｋ６２１７−４：２００１に記載のＤＢＰ吸収量の測定方法−Ｂ法（へら練り法）に準ずる。すなわち、試料１ｇを平滑なガラス板（３００ｍｍ×３００ｍｍ）の上に置き、所定のヘラを用いて、粉体が粒状であればこれを砕く。その上に、ビュレツトを用いてＤＢＰを少しずつ滴下し、試料と混ぜ、へらで練りながら水を添加し、混合物が均−になった時点での消費したＤＢＰ量を求める。この操作は１０〜１５分で終了するようにする。 [DBP absorption]
According to JIS K6217-4: 2001, method for measuring DBP absorption amount-B method (sparing method). That is, 1 g of a sample is placed on a smooth glass plate (300 mm × 300 mm), and if a powder is granular, it is crushed using a predetermined spatula. Furthermore, DBP is dropped little by little using a burette, mixed with the sample, water is added while kneading with a spatula, and the amount of DBP consumed when the mixture becomes uniform is determined. This operation should be completed in 10-15 minutes.

［タップ密度］
金属製カップの中に、試料を入れ、自動タップ装置（ホソカワマイクロメディテックスラボラトリー社製、ＴＹＰＥ ＰＴ−Ｄ）を用いて振幅３ｃｍ、タップ速度１回／secで２０回タッピングを行った時の所定の体積（１ｃｍ３）を占める試料の質量（ｇ）を測定し、タップ密度を計算する。
［プレス圧縮性と密度比］
フエノール樹脂製の筒（高さ５０ｍｍ、外径３０ｍｍ、内径１０ｍｍ）の中に、金属製円柱（直径１０ｍｍ）を差込み、該円柱端に所定量の試料を載せる。次に、別の金属製円柱（直径１０ｍｍ）を、別方向から該筒中に差込み、ハンドプレスで徐々に該試料に圧力を加え、５分間で１ＭＰａまで圧縮する。このとき上部の円柱が沈んだ距離（圧縮前後の距離）を計測する。該距離、試料量、フェノール樹脂製の筒の体積から圧縮時の密度が求められ、これとタップ密度から、式（１）により、試料の密度比を求める。 [Tap density]
Predetermined when a sample is placed in a metal cup and tapped 20 times at an amplitude of 3 cm and a tap speed of 1 / sec using an automatic tap device (type PT-D, manufactured by Hosokawa MicroMeditec Laboratory) The mass (g) of the sample occupying the volume (1 cm 3 ) is measured, and the tap density is calculated.
[Press compressibility and density ratio]
A metal cylinder (diameter 10 mm) is inserted into a phenol resin cylinder (height 50 mm, outer diameter 30 mm, inner diameter 10 mm), and a predetermined amount of sample is placed on the end of the cylinder. Next, another metal cylinder (diameter 10 mm) is inserted into the cylinder from another direction, and pressure is gradually applied to the sample with a hand press to compress it to 1 MPa in 5 minutes. At this time, the distance (the distance before and after compression) where the upper cylinder sinks is measured. The density at the time of compression is determined from the distance, the amount of sample, and the volume of the phenol resin tube, and the density ratio of the sample is determined from this and the tap density by the formula (1).

（実施例１）
［炭素粉末の製造］
天然黒鉛（ＳＥＣ社製、ＳＮＯ−１０、平均粒子径１０μｍ、密度比８．０１）９５質量部、および球晶黒鉛粉末（ＪＦＥケミカル社製、平均粒子径３μｍ、密度比１．７）５質量部を、メカノケミカル処理装置（奈良機械製作所製「ハイブリダイゼーションシステム」）を用いて、回転ローターの周速４０m/sec、処理時間５min以下の条件でメカノケミカル処理を行った。球晶黒鉛粉末と天然黒鉛が良好に分散した混合物が得られた。次いで、このメカノケミカル処理品を耐圧容器に入れ、不活性ガス雰囲気下、５００℃に昇温し、ベンゼンを気相で流通させ、３０min間ＣＶＤ処理を行い、球晶黒鉛粉末が天然黒鉛に付着し、複合化した炭素粉末を得た。該炭素粉末のＤＢＰ吸収量とプレス圧縮性（密度比）を表１に示した。 Example 1
[Production of carbon powder]
95 parts by mass of natural graphite (manufactured by SEC, SNO-10, average particle diameter 10 μm, density ratio 8.01), and spherulite graphite powder (manufactured by JFE Chemical, average particle diameter 3 μm, density ratio 1.7) 5 mass The part was subjected to mechanochemical treatment using a mechanochemical treatment apparatus (“Hybridization System” manufactured by Nara Machinery Co., Ltd.) under the conditions of a peripheral speed of the rotating rotor of 40 m / sec and a treatment time of 5 minutes or less. A mixture in which spherulite graphite powder and natural graphite were well dispersed was obtained. Next, the mechanochemically treated product is put in a pressure vessel, heated to 500 ° C. in an inert gas atmosphere, benzene is circulated in a gas phase, CVD treatment is performed for 30 minutes, and spherulite graphite powder adheres to natural graphite. As a result, a composite carbon powder was obtained. Table 1 shows the DBP absorption and press compressibility (density ratio) of the carbon powder.

［負極合剤ペーストの調製］
プラネタリーミキサーに前記炭素粉末を入れ、乾燥状態で攪拌した後、固形分にて、それぞれの質量％となるようにカルボキシメチルセルロースナトリウム１質量％、カルボキシ変性スチレンブタジエンゴムラテックスエマルジョン（ＪＳＲ社製）１質量％と水を加えて混合し、引続き攪拌を行い、水溶媒系の負極合剤ペーストを調製した。 [Preparation of negative electrode mixture paste]
The carbon powder is put into a planetary mixer and stirred in a dry state, and then 1% by mass of sodium carboxymethylcellulose and carboxy-modified styrene butadiene rubber latex emulsion (manufactured by JSR) 1 so as to be each mass% in solid content. Mass% and water were added and mixed, followed by stirring to prepare a water-based negative electrode mixture paste.

［作用電極の作製］
前記負極合剤ペーストを、銅箔上に均一な厚さになるように塗布し、さらに真空中９０℃で乾燥させた。次に、負極合剤層をローラープレスによって加圧し、さらに直径１５．５ｍｍの円形状に打ち抜くことで、集電材に密着した負極合剤層を有する作用電極を作製した。 [Production of working electrode]
The negative electrode mixture paste was applied on the copper foil so as to have a uniform thickness, and further dried at 90 ° C. in a vacuum. Next, the negative electrode mixture layer was pressurized by a roller press and punched into a circular shape having a diameter of 15.5 mm to produce a working electrode having a negative electrode mixture layer in close contact with the current collector.

［対極の作製］
リチウム金属箔をニッケルネットに押付け、直径１５．５ｍｍの円形状に打ち抜いて、ニッケルネットからなる集電材と、該集電材に密着したリチウム金属箔からなる対極を作製した。 [Production of counter electrode]
The lithium metal foil was pressed against a nickel net and punched into a circular shape with a diameter of 15.5 mm to produce a current collector made of nickel net and a counter electrode made of lithium metal foil in close contact with the current collector.

［電解液とセパレータ］
エチレンカーボネート３３vol％、メチルエチルカーボネート６７vol％の割合で混合してなる混合溶媒に、ＬｉＰＦ６を１mol/dm3となる濃度で溶解させ、非水電解液を調製した。得られた非水電解質液をポリプロピレン多孔質体に含潰させ、電解液が含浸したセパレータを作製した。 [Electrolyte and separator]
LiPF 6 was dissolved at a concentration of 1 mol / dm 3 in a mixed solvent obtained by mixing 33 vol% ethylene carbonate and 67 vol% methyl ethyl carbonate to prepare a non-aqueous electrolyte. The obtained non-aqueous electrolyte solution was impregnated in a polypropylene porous body to produce a separator impregnated with the electrolyte solution.

［評価電池の作製］
評価電池として図１に示すボタン型評価電池を作製した。
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を介してかしめられた密閉構造を形成し、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材７ａ、リチウム箔よりなる円板状の対極４、電解質液が含浸したセパレータ５、負極合剤からなる円板状の作用電極２、および銅箔からなる集電材７ｂが積層された電池構造である。 [Production of evaluation battery]
A button-type evaluation battery shown in FIG. 1 was produced as an evaluation battery.
The exterior cup 1 and the exterior can 3 form a sealed structure that is caulked through an insulating gasket 6 at the peripheral edge thereof, and in order from the inner surface of the exterior can 3, the current collector 7 a made of nickel net and the lithium foil In this battery structure, a disk-shaped counter electrode 4, a separator 5 impregnated with an electrolyte solution, a disk-shaped working electrode 2 made of a negative electrode mixture, and a current collector 7 b made of copper foil are laminated.

評価電池は、電解液を含浸させたセパレータ５を、集電材７ｂに密着した作用電極２と、集電材７ａに密着した対極４との間に挟んで積層した後、作用電極２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、外装カップ１と外装缶３との周縁部を絶縁ガスケット６を介してかしめ密閉して作製した。
評価電池は、実電池において、負極活物質として使用可能な炭素粉末を含有する作用電
極２と、リチウム金属箔からなる対極４とから構成される電池である。 In the evaluation battery, the separator 5 impregnated with the electrolytic solution was sandwiched between the working electrode 2 in close contact with the current collector 7b and the counter electrode 4 in close contact with the current collector 7a, and then the working electrode 2 was attached to the exterior cup 1. Inside, the counter electrode 4 was accommodated in the exterior can 3, the exterior cup 1 and the exterior can 3 were combined, and the peripheral edge of the exterior cup 1 and the exterior can 3 was caulked and sealed through an insulating gasket 6. .
The evaluation battery is a battery composed of a working electrode 2 containing carbon powder that can be used as a negative electrode active material and a counter electrode 4 made of a lithium metal foil.

該評価電池について、２５℃で下記のような充放電試験を行い、放電容量、初回充放電効率、急速充電効率およびサイクル特性を測定した。炭素粉末１ｇ当りの放電容量（ｍＡｈ／ｇ）、初回充放電効率（％）、急速充電効率（％）、急速放電効率（％）およびサイクル特性（％）を表１に示した。また、電極密度（ｇ／ｃｍ３）も表１に示した。 The evaluation battery was subjected to the following charge / discharge test at 25 ° C., and the discharge capacity, initial charge / discharge efficiency, rapid charge efficiency, and cycle characteristics were measured. Table 1 shows the discharge capacity (mAh / g), initial charge / discharge efficiency (%), rapid charge efficiency (%), rapid discharge efficiency (%), and cycle characteristics (%) per gram of carbon powder. The electrode density (g / cm 3 ) is also shown in Table 1.

［放電容量と初回充放電効率］
０．９ｍＡの電流値で回路電圧が０ｍＶに達するまで定電流充電を行い、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後、１２０min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った。このとき第１サイクルにおける通電量から充電容量と放電容量を求め、次式（２）から初回充放電効率を計算した。
初回充放電効率（％）＝（放電容量／充電容量）×１００ （２）
なおこの試験では、リチウムイオンを炭素粉末中にドープする過程を充電、炭素粉末から脱ドープする過程を放電とした。 [Discharge capacity and initial charge / discharge efficiency]
Constant current charging is performed until the circuit voltage reaches 0 mV at a current value of 0.9 mA, switching to constant voltage charging is performed when the circuit voltage reaches 0 mV, and charging is continued until the current value reaches 20 μA, and then 120 min. I paused for a while.
Next, constant current discharge was performed at a current value of 0.9 mA until the circuit voltage reached 1.5V. At this time, the charge capacity and the discharge capacity were obtained from the energization amount in the first cycle, and the initial charge / discharge efficiency was calculated from the following equation (2).
Initial charge / discharge efficiency (%) = (discharge capacity / charge capacity) × 100 (2)
In this test, the process of doping lithium ions into the carbon powder was charged, and the process of dedoping from the carbon powder was discharge.

［急速充電効率］
前記に引き続き、第２サイクルにて高速充電を行なった。電流値を５倍の４．５ｍＡとして、回路電圧が０ｍＶに達するまで定電流充電を行い、充電容量を求め、次式（３）から急速充電効率を計算した。
急速充電効率（％）＝（第２サイクルにおける定電流充電容量／
第１サイクルにおける放電容量）×１００ （３） [Quick charging efficiency]
Following the above, high-speed charging was performed in the second cycle. Constant current charging was performed until the circuit voltage reached 0 mV, with the current value being 5 times 4.5 mA, the charging capacity was obtained, and the rapid charging efficiency was calculated from the following equation (3).
Rapid charging efficiency (%) = (Constant current charging capacity in the second cycle /
Discharge capacity in the first cycle) × 100 (3)

［急速放電効率］
前記に引き続き、第３サイクルにて高速放電を行なった。電流債を１５倍の１３．５ｍＡとして、回路電圧が２．５Ｖに達するまで定電流放電を行い、放電容量を求め、次式（４）から急速放電効率を計算した。
急速放電効率（％）＝（第３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 （４） [Rapid discharge efficiency]
Following the above, high-speed discharge was performed in the third cycle. The current bond was set to 15 times 13.5 mA, constant current discharge was performed until the circuit voltage reached 2.5 V, the discharge capacity was obtained, and the rapid discharge efficiency was calculated from the following equation (4).
Rapid discharge efficiency (%) = (discharge capacity in the third cycle /
Discharge capacity in the first cycle) × 100 (4)

［サイクル特性］
別の評価電池を用いて回路電圧が０ｍＶに達するまで４．０ｍＡの定電流充電を行った後、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後、１２０min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い、この間の通電量から放電容量を求めた。この充放電を２０回繰返し、得られた放電容量から、次式（５）により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 （５） [Cycle characteristics]
Using a different evaluation battery, constant current charging of 4.0 mA is performed until the circuit voltage reaches 0 mV, then switching to constant voltage charging is performed when the circuit voltage reaches 0 mV, and charging is performed until the current value reaches 20 μA. After continuing, it paused for 120 minutes. Next, constant current discharge was performed until the circuit voltage reached 1.5 V at a current value of 4.0 mA, and the discharge capacity was obtained from the energization amount during this period. This charge / discharge was repeated 20 times, and the cycle characteristics were calculated from the obtained discharge capacity according to the following equation (5).
Cycle characteristics (%) = (discharge capacity in the 20th cycle /
Discharge capacity in the first cycle) × 100 (5)

［電極密度］
作用電極の面積、厚さ、質量および集電板の厚さ、質量から負極合剤の密度を求め、これを電極密度とした。 [Electrode density]
The density of the negative electrode mixture was determined from the area, thickness, and mass of the working electrode, and the thickness and mass of the current collector, and this was used as the electrode density.

（実施例２）
天然黒鉛（ＳＥＣ社製、ＳＮＯ−１０、平均粒子径１０μｍ、密度比８．０１）９５質量部、およびサーマルカーボンブラック粉末（平均粒子径０．３μｍ、ＤＢＰ吸収量３０ｃｍ３／１００ｇ、密度比２）５質量部を混合し、実施例１と同様にしてメカノケミカル処理を行った。次にプラネタリーミキサーに、該メカノケミカル処理品を入れ、カルボキシメチルセルロース３質量部と蒸留水１００質量部からなる溶液を添加し、３０ｒｐｍで、１ｈｒ間混練し、天然黒鉛にカーボンブラックが付着した混練物を得た。その後、該混練物の混練を２０ｒｐｍで続行しながら、６０℃に昇温し、水分を蒸発させ、さらに真空下で該混練物の乾燥を行った。該混練物を窒素ガス中、７００℃で焼成して、カルボキシメチルセルロースを分解して炭素粉末を得た。得られた炭素粉末のＤＢＰ吸収量と密度比を表１に示した。
該炭素粉末から、実施例１と同様な方法と条件で、負極合剤ペースト、負極および評価電池を作製して、実施例１と同様に、充放電特性を評価した。結果を表１に示した。 (Example 2)
Natural graphite (SEC Co., SNO-10, average particle size 10 [mu] m, density ratio 8.01) 95 parts by mass, and thermal carbon black powder (average particle diameter 0.3 [mu] m, DBP absorption 30 cm 3/100 g, a density ratio of 2 ) 5 parts by mass were mixed and subjected to mechanochemical treatment in the same manner as in Example 1. Next, the mechanochemically treated product is put into a planetary mixer, a solution consisting of 3 parts by mass of carboxymethyl cellulose and 100 parts by mass of distilled water is added, kneaded at 30 rpm for 1 hr, and kneaded with carbon black attached to natural graphite. I got a thing. Then, while continuing kneading | mixing of this kneaded material at 20 rpm, it heated up at 60 degreeC, the water | moisture content was evaporated, and also this kneaded material was dried under vacuum. The kneaded product was calcined at 700 ° C. in nitrogen gas to decompose carboxymethyl cellulose to obtain carbon powder. Table 1 shows the DBP absorption and density ratio of the obtained carbon powder.
From this carbon powder, a negative electrode mixture paste, a negative electrode, and an evaluation battery were produced in the same manner and under the same conditions as in Example 1, and the charge / discharge characteristics were evaluated in the same manner as in Example 1. The results are shown in Table 1.

（実施例３）
天然黒鉛（ＳＥＣ社製、ＳＮＯ−１０、平均粒子径１０μｍ、密度比８．０１）９５質量部、およびサーマルカーボンブラック粉末（平均粒子径０．３μｍ、ＤＢＰ吸収量３８ｃｍ３／１００ｇ、密度比２）５質量部を混合し、実施例１と同様にしてメカノケミカル処理を行った。次に、プラネタリーミキサーに、該メカノケミカル処理品を入れ、液状のフエノール樹脂３質量部とエタノール１００質量部を添加し、３０ｒｐｍで、１ｈｒ間混練し、天然黒鉛にカーボンブラックが付着した混練物を得た。その後、該混練物の混練を２０ｒｐｍで続行しながら、６０℃に昇温し、エタノールを蒸発させ、さらに真空下にて、該混練物の乾燥を行った。該混練物を窒素ガス中、７００℃で焼成して、フエノール樹脂を分解して炭素粉末を得た。得られた炭素粉末のＤＢＰ吸収量と密度比を表１に示した。
該炭素粉末から、実施例１と同様な方法と条件で、負極合剤ペースト、負極および評価電池を作製して、実施例１と同様に、充放電特性を評価した。結果を表１に示した。 (Example 3)
Natural graphite (SEC Co., SNO-10, average particle size 10 [mu] m, density ratio 8.01) 95 parts by mass, and thermal carbon black powder (average particle diameter 0.3 [mu] m, DBP absorption 38cm 3/100 g, a density ratio of 2 ) 5 parts by mass were mixed and subjected to mechanochemical treatment in the same manner as in Example 1. Next, the mechanochemically treated product is put into a planetary mixer, 3 parts by mass of a liquid phenol resin and 100 parts by mass of ethanol are added, kneaded at 30 rpm for 1 hr, and a kneaded product in which carbon black adheres to natural graphite. Got. Then, while continuing kneading | mixing of this kneaded material at 20 rpm, it heated up at 60 degreeC, ethanol was evaporated, and also this kneaded material was dried under vacuum. The kneaded product was baked in nitrogen gas at 700 ° C. to decompose the phenol resin to obtain a carbon powder. Table 1 shows the DBP absorption and density ratio of the obtained carbon powder.
From this carbon powder, a negative electrode mixture paste, a negative electrode, and an evaluation battery were produced in the same manner and under the same conditions as in Example 1, and the charge / discharge characteristics were evaluated in the same manner as in Example 1. The results are shown in Table 1.

（比較例１）
実施例１の天然黒鉛（ＳＥＣ社製、ＳＮＯ−１０、平均粒子径１０μｍ、密度比８．０１）自体のＤＢＰ吸収量を測定し、その結果を表１に示した。
該天然黒鉛から、実施例１と同様な方法と条件で、負極合剤ペースト、負極および評価電池を作製して、実施例１と同様に、充放電特性を評価した。結果を表１に示した。 (Comparative Example 1)
The amount of DBP absorption of natural graphite of Example 1 (manufactured by SEC, SNO-10, average particle diameter 10 μm, density ratio 8.01) itself was measured, and the results are shown in Table 1.
From the natural graphite, a negative electrode mixture paste, a negative electrode, and an evaluation battery were produced in the same manner and under the same conditions as in Example 1, and the charge / discharge characteristics were evaluated in the same manner as in Example 1. The results are shown in Table 1.

（比較例２）
天然黒鉛（ＳＥＣ社製、ＳＮＯ−５、平均粒子径５μｍ、密度比８．７４）自体のＤＢＰ吸収量と密度比を測定し、その結果を表１に示した。
該天然黒鉛から、実施例１と同様な方法と条件で、負極合剤ペースト、負極および評価電池を作製して、実施例１と同様に、充放電特性を評価した。結果を表１に示した。 (Comparative Example 2)
The DBP absorption and density ratio of natural graphite (manufactured by SEC, SNO-5, average particle size 5 μm, density ratio 8.74) itself were measured, and the results are shown in Table 1.
From the natural graphite, a negative electrode mixture paste, a negative electrode, and an evaluation battery were produced in the same manner and under the same conditions as in Example 1, and the charge / discharge characteristics were evaluated in the same manner as in Example 1. The results are shown in Table 1.

（比較例３）
天然黒鉛（ＳＥＣ社製、ＳＮＯ−５、平均粒子径５μｍ、密度比８．７４）９５質量部と、球晶黒鉛（ＪＦＥケミカル社製、平均粒子径１３μｍ、密度比１．６、比表面積０．９ｍ２／ｇ）５質量部を混合した。該混合物から、メカノケミカル処理しない他は、実施例１と同様な方法と条件で、負極合剤、ペースト、負極および評価電池を作製して、実施例１と同様に充放電と特性を評価した。得られた混合物のＤＢＰ吸収量と密度比を測定し、その結果を表１に示した。 (Comparative Example 3)
95 parts by mass of natural graphite (manufactured by SEC, SNO-5, average particle size 5 μm, density ratio 8.74) and spherulite graphite (manufactured by JFE Chemical Co., Ltd., average particle size 13 μm, density ratio 1.6, specific surface area 0) .9 m 2 / g) 5 parts by mass were mixed. A negative electrode mixture, a paste, a negative electrode, and an evaluation battery were prepared from the mixture in the same manner and conditions as in Example 1 except that no mechanochemical treatment was performed, and charge / discharge and characteristics were evaluated in the same manner as in Example 1. . The DBP absorption amount and density ratio of the obtained mixture were measured, and the results are shown in Table 1.

（比較例４）
天然黒鉛（ＳＥＣ社製、ＳＮＯ−１０、平均粒子径１０μｍ、密度比８．０１）９５質量部と、球晶黒鉛粉末（ＪＦＥケミカル社製、平均粒子径１３μｍ、密度比１．６、比表面積０．９ｍ２／ｇ）５質量部を用いて、実施例１と同様な方法と条件で、メカノケミカル処理を行った。
該メカノケミカル処理品について、ＣＶＤ処理をしない他は、実施例１と同様な方法と条件で、負極合剤、ペースト、負極および評価電池を作製して、実施例１と同様に充放電と特性を評価した。メカノケミカル処理品のＤＢＰ吸収量と密度比を測定し、その結果を表１に示した。 (Comparative Example 4)
95 parts by mass of natural graphite (manufactured by SEC, SNO-10, average particle size 10 μm, density ratio 8.01) and spherulite graphite powder (manufactured by JFE Chemical Co., Ltd., average particle size 13 μm, density ratio 1.6, specific surface area) 0.9 m 2 / g) Using 5 parts by mass, the mechanochemical treatment was performed under the same method and conditions as in Example 1.
With respect to the mechanochemically treated product, a negative electrode mixture, a paste, a negative electrode and an evaluation battery were prepared in the same manner and conditions as in Example 1 except that the CVD treatment was not performed. Evaluated. The DBP absorption amount and density ratio of the mechanochemically processed product were measured, and the results are shown in Table 1.

比較例１〜４の炭素粉末を負極材料に用いた二次電池は、いずれも、高電極密度では、急速充電効率、サイクル特性の悪化が認められる。一方、実施例１〜３の炭素粉末を負極材料に用いた二次電池は、いずれも、高電極密度では、急速充電効率、急速放電効率、サイクル特性が向上している。   In any of the secondary batteries using the carbon powders of Comparative Examples 1 to 4 as the negative electrode material, rapid charging efficiency and deterioration of cycle characteristics are recognized at a high electrode density. On the other hand, the secondary batteries using the carbon powders of Examples 1 to 3 as the negative electrode material have improved rapid charge efficiency, rapid discharge efficiency, and cycle characteristics at a high electrode density.

Figure 0004839180
Figure 0004839180

炭素粉末の充放電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 charging / discharging characteristic of carbon powder.

符号の説明Explanation of symbols

１ 外装カップ
２ 作用電極
３ 外装缶
４ 対極
５ セパレータ
６ 絶縁ガスケット
７ａ、７ｂ 集電材 DESCRIPTION OF SYMBOLS 1 Exterior cup 2 Working electrode 3 Exterior can 4 Counter electrode 5 Separator 6 Insulating gasket 7a, 7b Current collector

Claims (7)

ジブチルフタレートの吸収量が１０ｃｍ３／１００ｇ以上、３０ｃｍ３／１００ｇ以下であり、かつ下記式（１）で示す密度比が４〜６．５であることを特徴とする炭素粉末。
密度比＝（圧力１ＭＰａをかけたときの密度）／（タップ密度）・・・・（１） Absorption of dibutyl phthalate 10 cm 3/100 g or more, 30 cm 3/100 g or less and a carbon powder density ratio represented by the following formula (1) is characterized in that it is a 4 to 6.5.
Density ratio = (Density when pressure is 1 MPa) / (Tap density) (1) 黒鉛材料と、下記式（１）で示される密度比および平均粒子径が該黒鉛材料よりも小さい炭素材料とをメカノケミカル処理した後、さらに結合剤を用いて、該黒鉛材料に該炭素材料を付着させることを特徴とする炭素粉末の製造方法。
密度比＝（圧力１ＭＰａをかけたときの密度）／（タップ密度）・・・・（１） After mechanochemical treatment of the graphite material and a carbon material having a density ratio and an average particle diameter smaller than the graphite material represented by the following formula (1), the carbon material is further applied to the graphite material using a binder. A method for producing a carbon powder, characterized by adhering.
Density ratio = (Density when pressure is 1 MPa) / (Tap density) (1) 前記黒鉛材料の密度比が３〜９であり、平均粒子径が５０μｍ以下であることを特徴とする請求項２に記載の炭素粉末の製造方法。   The method for producing carbon powder according to claim 2, wherein the density ratio of the graphite material is 3 to 9, and the average particle diameter is 50 µm or less. 黒鉛材料１００質量部と、下記式（１）で示される密度比および平均粒子径が該黒鉛材料よりも小さい炭素材料１〜５０質量部とをメカノケミカル処理した後、さらに結合剤を用いて、該黒鉛材料に該炭素材料を付着させることを特徴とするジブチルフタレートの吸収量が１０ｃｍ３／１００ｇ以上、３０ｃｍ３／１００ｇ以下であり、かつ下記式（１）で示す密度比が４〜６．５である請求項２または３に記載の炭素粉末の製造方法。
密度比＝（圧力１ＭＰａをかけたときの密度）／（タップ密度）・・・・（１） After mechanochemical treatment of 100 parts by mass of the graphite material and 1 to 50 parts by mass of the carbon material having a density ratio and an average particle diameter represented by the following formula (1) smaller than the graphite material, using a binder, absorption of dibutyl phthalate for causing the graphite material is deposited the carbon material is 10 cm 3/100 g or more, or less 30 cm 3/100 g, and the density ratio shown by the following formula (1) is 4-6. The method for producing carbon powder according to claim 2 or 3, wherein the carbon powder is 5.
Density ratio = (Density when pressure is 1 MPa) / (Tap density) (1) 請求項１に記載の炭素粉末を含むことを特徴とするリチウムイオン二次電池用負極材料。   A negative electrode material for a lithium ion secondary battery, comprising the carbon powder according to claim 1. 請求項５に記載のリチウムイオン二次電池用負極材料からなることを特徴とするリチウムイオン二次電池用負極。   A negative electrode for a lithium ion secondary battery comprising the negative electrode material for a lithium ion secondary battery according to claim 5. 請求項６に記載のリチウムイオン二次電池用負極を設けたことを特徴とするリチウムイオン二次電池。   A lithium ion secondary battery comprising the negative electrode for a lithium ion secondary battery according to claim 6.
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