JP4032479B2 - Non-aqueous electrolyte secondary battery negative electrode material and non-aqueous electrolyte secondary battery provided with a negative electrode using the negative electrode material - Google Patents

Description

【００３９】
表１より本発明の実施例における負極材料を用いた電池は、それぞれの炭素材料（ｄ（００２）＝３．３５〜４．１Å）別における１サイクル目の放電容量は、比較電池よりも高容量になっている。つまり、本発明を実施した電池１，２，３では比較電池４，５よりも、また、本発明を実施した電池６，７では比較電池８，９よりも、本発明を実施した電池１０，１１，１２では比較電池１３，１４よりも、本発明を実施した電池１５，１６では比較電池１７，１８よりも、本発明を実施した電池１９，２０では比較電池２１，２２よりも１サイクル目の放電容量が高くなっていることがわかる。
【００４０】
また、３００サイクル目の放電容量を比べると、炭素粒子に金属もしくは合金または酸化物または窒化物を化学結合させたものや担持させた本発明を実施した各電池は、炭素のみの比較電池（表１中の結合させる金属，合金がなしの電池）に比べ大きな放電容量を示している。
【００４１】
そして、１０００サイクル目になると、本発明を実施した電池１，２，３，６，７，１０，１１，１２，１５，１６，１９，２０においては、依然高容量を保っており、サイクル劣化の少ないことがわかる。この要因としては、本発明の負極材料が炭素粒子の界面において炭素と金属もしくは合金または酸化物または窒化物との反応により炭化物を作り、炭素粒子と金属もしくは合金または酸化物または窒化物が化学結合により強力に結合していることで、充放電を繰り返すことによる金属もしくは合金または酸化物または窒化物が自分自身の膨張，収縮で、炭素粒子から脱離することが防止され、その結果、極板劣化が小さく抑えられたためと考えられる。しかし、単に炭素粒子に金属を担持させた比較電池５，９，１４，１８，２２においては、放電容量が炭素のみで作製された比較電池よりも小さくなっている。この原因としては、充放電サイクルによる担持金属の膨張，収縮により担持金属が電極から離れ不活性化したことによるものと考えられる。さらに、この金属の劣化過程において母材の炭素粒子に何らかの悪影響を与え、放電容量が炭素粒子のみで作製された比較電池よりも小さくなったものと考えられる。
【００４２】
安全性に対する判断は、各サンプルを負極材料に用いた電池を１０００サイクルの充放電を行い、充電状態で電池を分解して取り出した負極材料の、ＴＧ−ＤＴＡの熱測定を室温から３５０℃の温度範囲で行い、その温度範囲内において熱量の最大値を示す温度が、炭素材料のみからなる負極材料の場合と比較して高いか低いかにより安全性を判断した。
【００４３】
その結果、本発明の負極材料では、炭素材料のみで構成された負極材料より熱量の最大値を示す温度が高かった。そして、炭素粒子に単に金属を担持させた負極材料では、炭素材料のみで構成された負極材料より熱量の最大値を示す温度が低かった。
【００４４】
このように本発明の負極材料は、安全性の面においても優れているものであることがわかる。
【００４５】
以上のように、本発明の負極材料を非水電解質二次電池に用いれば、炭素粒子のみの材料や単に金属を炭素粒子に担持させた材料を用いた二次電池よりも高容量で、優れたサイクル特性，高い安全性を示す非水電解質二次電池を提供することができる。
【００４６】
（実施例２）
次に、実施例１における炭素▲１▼を用い、その炭素▲１▼の平均粒径を０．５〜７０μｍに篩い分けを行い、それぞれの粒径の炭素に平均粒径０．１μｍのＳｉ粒子を熱プラズマ法にて化学結合させた。この時、Ｘ線回折やＸＰＳの解析により、炭素粒子界面にＳｉＣが形成されていることを確認した。また、炭素粒子の平均粒径の違いにより、化学結合するＳｉ量にも差異が生じたので、各平均粒径の炭素粒子に対するＳｉ量（重量比率）を化学分析にて求めた。また、比較例としてＳｉのかわりに平均粒径０．１μｍのＡｇを０（炭素▲１▼のみ）〜５０重量％担持させた炭素粒子を用いた。Ａｇの担持では実施例１と同様、炭素界面に炭素とＡｇの炭化物は見られなかった。
【００４７】
これらサンプルを負極活物質として非水電解質二次電池を実施例１と同方法にて作製した。そして電池の評価は、実施例１と同じように０．２Ｃ（１Ｃ充放電とは、１時間で７８０ｍＡｈの充放電に相当）定電流充放電サイクル試験を行った。また、充電上限電圧は４．２Ｖ、放電下限電圧は３．０Ｖとした。結果として、初期，３００サイクル後，１０００サイクル後の放電容量を表２に示した。
【００４８】
【表２】

【００４９】
表２（Ａ）より、炭素の平均粒径が０．５〜５０μｍ範囲の電池（電池２３〜２６）の１サイクル目（初期）の放電容量は、黒鉛の理論容量を越えるほどの高容量であることがわかる。
【００５０】
電池２７，２８（平均粒径がそれぞれ７０，１００μｍ）では、Ｓｉ量が少ないためか１サイクル目の放電容量は、表２（Ｂ）に示す比較例の電池３５の炭素▲１▼のみで作製された電池に比較して若干大きくなっているが、１０００サイクル後の放電容量では炭素▲１▼のみで作製された電池よりも放電容量が若干小さくなっている。この原因としては、炭素に化学結合させた若干のＳｉ量がサイクル特性に何らかの悪影響を及ぼしているものと考えられる。また、電池２３の場合は、炭素粒子に化学結合させたＳｉ量が炭素粒子に対し４０重量％あり、そのため１サイクル目の放電容量は３２４３ｍＡｈもあるが、１０００サイクル目では放電容量が炭素のみで作製された表２（Ｂ）に示す比較例の電池３５よりも小さなものとなった。この原因は、負極材料全体に占めるＳｉ量が多すぎるため、充放電サイクルに伴うＳｉの膨張，収縮も大きくなり、過電圧が大きくなったためと考えられる。よって、炭素粒子の平均粒径は１〜５０μｍの場合が優れたサイクル特性を示すことがわかる。
【００５１】
比較例として表２（Ｂ）の炭素平均粒径が１〜５０μｍの場合、１サイクル目の放電容量は炭素▲１▼のみ使用の電池３５より大きくなるが、１０００サイクル後ではそれ以下になってしまう。この原因は、Ａｇが炭素粒子と強く結合していないため、充放電サイクルを繰り返していくと、Ａｇの膨張，収縮によりＡｇが炭素粒子より離れＡｇ粒子が不活性化し、極板の緩みが生じて炭素自身も放電容量の低下が起こったものと考えられる。
【００５２】
また、安全性に関しても実施例１と同様に、各サンプルを負極材料に用いた電池を１０００サイクルの充放電を行い、充電状態で電池を分解し、その負極材料のＴＧ−ＤＴＡ測定を室温から３５０℃の温度範囲で行い、その温度範囲内で熱量の最大値を示す温度を、炭素のみで構成される負極材料において示す温度との比較によって安全性を判断した。
【００５３】
その結果、炭素▲１▼の平均粒径が１〜１００μｍ（電池２４〜２８）の負極材料の熱量の最大値を示す温度は、炭素材料のみの負極材料より高く、比較例の電池の負極材料の熱量の最大値を示す温度は、全て炭素材料のみの負極材料より低かった。
【００５４】
以上より、本発明の負極材料における炭素粒子は平均粒径が１〜５０μｍで、また炭素粒子に結合する金属もしくは合金の炭素粒子に対する重量比は、１〜２０重量％の場合、容量，サイクル特性，安全性に対し、より一層の優れた特性を示すことがわかる。
【００５５】
（実施例３）
次に、実施例１の平均粒径２０μｍの炭素▲１▼を用い、その炭素▲１▼に平均粒径が０．００５〜１０μｍのＳｉ粒子を熱プラズマ法にて結合させた。この時、Ｘ線回折やＸＰＳの解析により、炭素粒子界面にＳｉＣが形成されていることを確認した。また、比較例としてＳｉのかわりに平均粒径が０．００５〜１０μｍのＡｇに担持させたものを用いた。Ａｇでは実施例１と同様、炭素界面に炭化物は見られなかった。
【００５６】
このサンプルを負極活物質として非水電解質二次電池を実施例１と同方法にて作製した。そして電池の評価は、実施例１と同じように０．２Ｃ（１Ｃ充放電とは、１時間で７８０ｍＡｈの充放電に相当）定電流充放電サイクル試験を行い、充電上限電圧は４．２Ｖ，放電下限電圧は３．０Ｖとした。結果は、初期，３００サイクル後，１０００サイクル後の放電容量を表３（Ａ）（Ｓｉに関するもの），表３（Ｂ）（比較例としてＡｇに関するもの）に示した。
【００５７】
【表３】

【００５８】
表３（Ａ）より、炭素粒子と結合させるＳｉの平均粒径は、０．００５〜１０μｍの範囲では１サイクル目の放電容量が、前記表２（Ｂ）に示す電池３５の炭素▲１▼（平均粒径２０μｍ）のみの場合（８００ｍＡｈ）より大きくなり、電池４０，４１のＳｉの平均粒径が２〜１０μｍ範囲では、１０００サイクル目の放電容量がいずれも５００ｍＡｈ以下と極端に低下している。これはＳｉ粒子が２μｍ以上になると、炭素粒子とＳｉとの界面に炭化物を形成して強力に化学結合する効果が薄らいでしまい、金属や合金等が膨張，収縮で炭素粒子から脱落してしまい、サイクル劣化が起こってしまうものと考えられる。
【００５９】
表３（Ｂ）の炭素粒子にＡｇを担持した場合では、１サイクル目の放電容量は先述した表２（Ｂ）の電池３５の放電容量以上を示すが、１０００サイクル後では表記した全ての平均粒径において５００ｍＡｈ程度以下になる。この原因としては実施例２と同様に、Ａｇが炭素粒子と強く結合していないため、充放電サイクルを繰り返していくと、Ａｇの膨張，収縮によりＡｇが炭素粒子より離れＡｇ粒子の不活性化、そして極板膨張による炭素粒子の放電容量の低下を招き、１０００サイクル後の放電容量は黒鉛以下になると考えられる。
【００６０】
安全性に関しても実施例１と同様に、各サンプルを負極材料に用いた電池を１０００サイクルの充放電を行い、充電状態で電池を分解し、その負極材料のＴＧ−ＤＴＡ測定を室温から３５０℃の温度範囲で行い、その温度範囲内で熱量の最大値を示す温度を、炭素のみで構成される負極材料において示す温度との比較によって安全性を判断した。
【００６１】
その結果、Ｓｉの平均粒径が０．０１〜１μｍ、すなわち電池３７〜３９の負極材料の熱量の最大値を示す温度は、炭素材料のみの負極材料より高かった。しかし、電池３６，４０，４１，４２〜４７の負極材料の熱量の最大値を示す温度は、炭素材料のみの負極材料より低かった。
【００６２】
電池３６は、Ｓｉの平均粒径が０．００５μｍと小さいため比表面積がかなり大きく、熱量の最大値を示す温度が炭素材料のみの負極材料より高くなったものと考えられる。
【００６３】
電池４０，４１では、炭素粒子に結合したＳｉが大きく、大きな粒子の金属，合金で見られるように充放電サイクルを繰り返すとＳｉが微細化し、比表面積がかなり大きくなり、熱量の最大値を示す温度が炭素材料のみの負極材料より高くなったものと考えられる。
【００６４】
電池４２〜４７では、炭素粒子とＡｇとの結合が弱いため、１０００サイクルも充放電を繰り返すとＡｇがリチウムと結合したままの状態で炭素粒子から脱離し、それにより比表面積の増大を招き、熱量の最大値を示す温度が炭素材料のみの負極材料より高くなったものと考えられる。
【００６５】
以上より、本発明の負極材料における炭素粒子に化学結合させる金属もしくは合金の平均粒径が、０．０１〜１μｍの場合、容量，サイクル特性，安全性に対し、より一層の優れた特性を示すことがわかる。
【００６６】
（実施例４）
次に、平均粒径２０μｍの実施例１の炭素▲１▼に平均粒径０．１μｍのＳｉ粒子を熱プラズマ法にて化学結合させた炭素粒子（Ｘ線回折やＥＰＭＡの解析で炭素粒子界面にＳｉＣが形成されていることを確認）と、導電材としてのアセチレンブラック（その他、導電材としては実施例１に示した炭素類、全てが使用できる）を混合したものを用いて負極極板を作製し円筒形電池を作製した。
【００６７】
そして電池の評価は、実施例１と同じように０．２Ｃ（１Ｃ充放電とは、１時間で７８０ｍＡｈの充放電に相当）定電流充放電サイクル試験を行った。充電上限電圧は４．２Ｖ，放電下限電圧は３．０Ｖとした。結果として、初期，３００サイクル後，１０００サイクル後の放電容量を表４に示した。また、比較例として導電材なしで作製した電池の評価も行った。
【００６８】
【表４】

【００６９】
表４より、電池４９〜５１では１サイクル目の放電容量は、比較例の電池５３に比べ導電材を混合したことにより若干低下しているが、１０００サイクル目の放電容量を比較すると比較例の電池５３よりも高容量になることがわかる。これは導電材を加えると導電性の向上により直接抵抗成分が低く抑えられ過電圧の低下により、放電容量の維持率が向上したものによると考えられる。
【００７０】
しかし、電池４８のように導電材が少ないとその効果が得られず、また電池５２のように導電材が多いと負極材料の高容量化ができない。
【００７１】
安全性に関しても実施例１と同様に、各サンプルを負極材料に用いた電池を１０００サイクルの充放電を行い、充電状態で電池を分解し、その負極材料のＴＧ−ＤＴＡ測定を室温から３５０℃の温度範囲で行い、その温度範囲内で熱量の最大値を示す温度を、炭素のみで構成される負極材料において示す温度との比較によって安全性を判断した。
【００７２】
その結果、電池４８〜５２や、さらに比較例の電池５３においても、それらの負極材料の熱量の最大値を示す温度は、炭素材料のみの負極材料より高かった。
【００７３】
以上より、本発明の負極材料に導電材として炭素を５〜８０重量％含有させることにより安全性は全く問題なく、初期容量は若干減少するもののさらにサイクル特性の優れた電池特性を得ることができることがわかる。
【００７４】
さらに、本発明の負極材料を非水電解質二次電池に用いる場合、正極活物質には、リチウムを含有するＣｏ，Ｎｉ，Ｍｎ遷移金属化合物以外に、Ｔｉ，Ｍｏ，Ｗ，Ｎｂ，Ｖ，Ｆｅ，Ｃｒ等の１種類以上の遷移金属の複合酸化物や複合硫化物等の化合物を用いても同等の効果が得られる。特に、高電圧，高エネルギー密度に関しては、ＬｉＣｏＯ₂ ，ＬｉＮｉＯ₂ ，ＬｉＭｎ₂Ｏ₄ 等の正極活物質が好適である。
【００７５】
そして、実施例１〜４において非水電解質二次電池に用いられた電解質の溶媒としては、ＥＣ，ＰＣ，ＤＭＣ，ＥＭＣ，ＤＥＣ等の環状，鎖状炭酸エステル類、γ−ブチロラクトン等のγ−ラクトン類、ＤＭＥ，ＤＥＥ，ＥＭＥ等の鎖状炭酸エーテル類、テトラヒドロフラン等の環状エーテル類、アセトニトリル等のニトリル類等から選ばれた溶媒、もしくは２種類以上の混合溶媒を用いても実施例のＥＣとＤＥＣを１：１で混合した場合と同等の効果が得られる。特に、ＥＣを必須成分として含む混合溶媒を使用することが好適である。
【００７６】
そして、非水電解質の溶質としては、ＬｉＡｓＦ₆ ，ＬｉＰＦ₆ ，ＬｉＡｌＣｌ₄ ，ＬｉＣｌＯ₄ ，ＬｉＣＦ₃ＳＯ₃ ，ＬｉＳｂＦ₆ ，ＬｉＳＣＮ，ＬｉＣｌ，ＬｉＣ₆ＨＳＯ₃ ，Ｌｉ（ＣＦ₃ＳＯ₂）₂ ，ＬｉＣ（ＣＦ₃ＳＯ₂）₃ ，Ｃ₄Ｆ₆ＳＯ₃Ｌｉ等のリチウム塩およびこれらの混合物を用いても実施例のＬｉＰＦ₆ と同様の効果が得られる。
【００７７】
また、電池の形状に関しては、本実施例では円筒形を用いたが、コイン形，角形，その他いかなる形状の電池でも使用できる。そして、本発明の負極活物質はポリマー電池の負極活物質としても有効である。
【００７８】
そして、請求項４ないし７記載の発明のいずれかの非水電解質二次電池で、かつ上記のいかなる電池形状においても、自動二輪車や電気自動車のモータを駆動する動力源に適用可能である。
【００７９】
【発明の効果】
本発明は、前述したようにリチウムの吸蔵ならびに放出のできる非水電解質二次電池の負極材料として、炭素粒子表面に、リチウムと合金を形成することができる金属が、炭素とその金属との高周波熱プラズマによる反応により炭化物を形成することで、炭素粒子と化学結合の状態にある複合炭素材料を用いることにより、高容量で優れたサイクル特性、そして高安全性を有する非水電解質二次電池を実現できる。
【図面の簡単な説明】
【図１】本発明の一実施例における負極を用いた円筒形電池の縦断面図
【符号の説明】
１ 正極
２ 正極リード板
３ 負極
４ 負極リード板
５ セパレータ
６ 上部絶縁板
７ 下部絶縁板
８ ケース
９ 封口板
１０ ガスケット
１１ 正極端子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-aqueous electrolyte secondary battery.
[0002]
[Prior art]
Non-aqueous electrolyte secondary batteries are small, light, and have a high energy density, and are therefore expected to contribute to making devices used portable and cordless.
[0003]
Conventionally, as a positive electrode active material of a nonaqueous electrolyte secondary battery, LiCoO₂, LiNiO₂, LiMn₂O_Four, V₂O_FiveOn the other hand, as the negative electrode active material, metal lithium, Li—Al alloy, Li—Pb alloy, etc. were considered, but when the charge / discharge cycle was repeated, dendritic lithium was Precipitation, growth, and finally through the separator may cause a short circuit between the positive and negative electrodes, which has not been put into practical use.
[0004]
Therefore, for safety reasons, some carbon materials such as graphite that can occlude and release lithium and have excellent cycle characteristics have been put into practical use.
[0005]
Further, in order to increase the charge / discharge capacity of the carbon material, as disclosed in JP-A-5-299073, the surface of the highly crystalline carbon particles forming the core is a film containing a Group VIII metal element. There are known carbon composites coated with carbon and further coated with carbon, and mixtures of carbon materials and metals that can be alloyed with lithium as disclosed in JP-A-2-121258.
[0006]
Further, as disclosed in JP-A-8-273702, a lithium secondary battery having high capacity and excellent charge / discharge cycle characteristics is known by supporting a metal that forms an alloy with lithium on carbon particles. .
[0007]
[Problems to be solved by the invention]
However, in the ones disclosed in JP-A-5-299073 and JP-A-2-121258, the theoretical capacity of the carbon itself is not drawn by coating the metal with carbon, and the output density is not sufficient. . Moreover, in the thing disclosed in Japanese Patent Application Laid-Open No. 8-273702, by carrying metal fine particles that can be alloyed with lithium on carbon, the capacity is larger than that of graphite and the charge / discharge cycle characteristics are improved. As a battery for automobiles, the capacity and cycle characteristics are insufficient, and there are also problems in terms of safety.
[0008]
[Means for Solving the Problems]
  In order to solve the problems described above, the present inventionLithium and alloys on the surface of carbon particles
The metal that can form the high frequency thermal plasmaA material that forms a carbide by a reaction with carbon and is in a chemical bond with carbon particles is used as a negative electrode material for a non-aqueous electrolyte secondary battery, and the negative electrode material for the non-aqueous electrolyte secondary battery is used for the negative electrode. Thus, a non-aqueous electrolyte secondary battery having a high capacity, excellent cycle characteristics, and high safety is to be provided.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present invention can be implemented by adopting the configurations described in each claim. In order to facilitate understanding of the embodiments, the technical background that characterizes the technology of the present invention will be clarified below.
[0010]
  The negative electrode material of the present invention can form an alloy with lithium in the capacity of existing carbon particles (having an interplanar spacing d (002) of 3.35-4.1 mm by X-ray diffraction).MetallicIncrease capacity by adding capacity, and further with carbon particlesWith metalBut the carbon particlessurfaceIn carbon and itsMetallicForming carbides composed of carbon particles and theirWith metalIt is a material that exhibits excellent cycle characteristics by chemically bonding between. Thus, with carbon particlesWith metalIt is a feature emphasized by the present invention that is strongly bonded by forming a carbide. As disclosed in Japanese Patent Application Laid-Open No. 8-273702, only metal particles capable of being alloyed with lithium are supported on carbon (in the example of Japanese Patent Application Laid-Open No. 8-273702, only a supported metal can be seen by X-ray diffraction). In this case, the carbide is not described), and the supported metal is easily detached from the carbon due to the expansion and contraction of the supported metal accompanying the insertion and extraction of lithium, and floats from the current collector after repeated cycles. The current collecting property of the metal deteriorates and becomes inactive. As a result, the cycle characteristics required for motorcycles and electric vehicles cannot be satisfied.
[0011]
  However, the negative electrode material of the present invention is simply carbon particles.To metalOf carbon particlessurfaceWith carbonMetallicForming carbides of composition, carbon andBetween metalsBy making the bond stronger by chemical bond,MetalBy preventing easy detachment from the carbon particles due to expansion and contraction, the cycle characteristics superior to the nonaqueous electrolyte secondary battery disclosed in JP-A-8-273702 are exhibited. In addition, more carbonMetalIt is also possible to combine them, and a considerably higher capacity can be expected than the nonaqueous electrolyte secondary battery disclosed in JP-A-8-273702.
[0012]
As described above, the negative electrode material of the present invention has excellent cycle characteristics capable of maintaining capacity at a high capacity even in cycles of 1000 to 2000 cycles and further.
[0013]
In addition, as in the technique disclosed in Japanese Patent Application Laid-Open No. 8-273702, in the case where Ag or Sn is supported on carbon particles, the bond between Ag or Sn and carbon is weak, so the charge / discharge cycle is repeated. Then, the supported metal is desorbed from the carbon particles by the expansion and contraction of the supported metal that occludes or releases lithium, and as a result, the current collecting property is reduced and the overvoltage is increased. Therefore, when the charge / discharge cycle is repeated 1000 times or more, the cycle deterioration becomes remarkable. In the cycle deterioration state, the desorbed metals exist in a state where lithium is occluded, and since these metals are in a thermally unstable state due to their large specific surface area, they are extremely dangerous from the viewpoint of safety. Is in a state. Thus, there is a problem in terms of safety simply by loading a metal on carbon particles.
[0014]
  However, even if the negative electrode material of the present invention is repeatedly charged and discharged, carbon andMetalSince carbides are formed at the carbon interface and chemically bonded to each other, the charge / discharge cycle is repeated.MetalSince there is no detachment from the carbon particles due to its own expansion and contraction, even if charging / discharging for 1000 cycles or more, there is no cycle deterioration except for the deterioration factor inherent to the carbon material. It does not accumulate in parts away from the top and has high safety.
[0015]
For the above reasons, by using the negative electrode material of the present invention, it is possible to provide a non-aqueous electrolyte secondary battery having high capacity, excellent cycle characteristics, and high safety.
[0016]
The materials used for carrying out the present invention are described in detail below.
Carbon particles obtained by calcining easily graphitizable carbon obtained from natural graphite, artificial graphite, petroleum, coal pitch or coke in a temperature range of 650 to 1000 ° C., infusible carbon, petroleum, coal pitch or coke And non-graphitizable carbon obtained by baking a resin or the like in a temperature range of 600 to 1300 ° C., and the shape thereof may be a spherical shape, a lump shape, a scale shape, a fiber shape, or a pulverized product thereof. Among these carbon materials, the interplanar spacing d (002) by X-ray diffractometry as described in claim 2 is preferably 3.35 to 4.1 mm, and the average particle size is 1 to 50 μm. Is preferred.
[0017]
  In addition to carbon particlesMetalAs a method of combining,The high frequency thermal plasma methodThere areThatCarbon particles in the processWith metalIs carbonsurfaceIt is necessary to set conditions so as to form carbides.
[0018]
  And, as a metal capable of forming an alloy with lithium, the claim1As described, it may be a metal element selected from the group consisting of Al, Ba, B, Ca, Si, Sr, and Mg.Preferably,Can form an alloy with lithiumMetallicThe average particle size is preferably 0.01 to 1 μm, and the weight ratio with respect to the carbon particles is preferably 1 to 20% by weight.
[0019]
As described above, in a non-aqueous electrolyte secondary battery having a non-aqueous electrolyte, a positive electrode, and a negative electrode capable of occluding and releasing lithium, the negative electrode having characteristics of claim 1 as a constituent material of the negative electrode By using the material, a non-aqueous electrolyte secondary battery having a high capacity, excellent cycle characteristics, and higher safety can be realized.
[0020]
The negative electrode active material in the nonaqueous electrolyte secondary battery of the present invention is preferably used by containing 5 to 80% by weight of carbon as a conductive material in the negative electrode material of the present invention, and the positive electrode active material is Co, Ni, Mn , Ti, Mo, W, Nb, V, Fe, Cr, etc. It is preferable to use a compound such as a composite oxide or composite sulfide of one or more transition metals, and particularly with regard to high voltage and high energy density, LiCoO₂, LiNiO₂, LiMn₂O_FourA positive electrode active material such as is preferable.
[0021]
Further, as a solvent for the non-aqueous electrolyte, ethylene carbonate (hereinafter referred to as EC), propylene carbonate (hereinafter referred to as PC), dimethyl carbonate (hereinafter referred to as DMC), ethyl methyl carbonate (hereinafter referred to as EMC), diethyl carbonate ( Hereinafter, cyclic carbonates such as DEC), γ-lactones such as γ-butyrolactone, 1,2-dimethoxyethane (hereinafter referred to as DME), 1,2-diethoxyethane (hereinafter referred to as DEE). ), A chain carbonate ether such as ethoxymethoxyethane (hereinafter referred to as EME), a cyclic ether such as tetrahydrofuran, a nitrile such as acetonitrile or the like, or a mixed solvent of two or more types is used. Particularly preferred are carbonate-based organic solvents. As the solute of the non-aqueous electrolyte, LiAsF₆, LiPF₆, LiAlCl_Four, LiClO_Four, LiCF_ThreeSO_Three, LiSbF₆, LiSCN, LiCl, LiC₆HSO_Three, Li (CF_ThreeSO₂)₂, LiC (CF_ThreeSO₂)_Three, C_FourF₆SO_ThreeLithium salts such as Li and mixtures thereof are used.
[0022]
  Claims8The invention described in claim is directed to a power source of a motor for driving a motorcycle.4Or7The use invention which can use the nonaqueous electrolyte secondary battery described in any one of the inventions described in the above is specified.
[0023]
  Claims9The invention described in claim is directed to a power source of a motor for driving an electric vehicle.4Or7The use invention which can use the nonaqueous electrolyte secondary battery described in any one of the inventions described in the above is specified.
[0024]
【Example】
Hereinafter, the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to these examples.
[0025]
Example 1
As the carbon particles, the following carbon particles (1) to (5) having an average particle diameter of 20 μm were used.
Carbon particles (1) were natural graphite of a high purity treated product.
Carbon particles (2) were artificial graphite obtained by heat-treating a carbonized product obtained from petroleum pitch at 2800 ° C.
The carbon particles {circle around (3)} were made into low-graphite easily graphitizable carbon that was heat-treated at 750 ° C. in an Ar atmosphere with an infusible petroleum pitch.
The carbon particles (4) were low-graphite non-graphitizable carbon obtained by heat-treating a phenol resin in an Ar atmosphere at 850 ° C.
Carbon particles (5) were amorphous carbon (high-temperature fired non-graphitizable carbon) obtained by crosslinking a phenol resin in the air and heat-treating at 1100 ° C.
[0026]
Examples of metals and alloys to be chemically bonded to these carbon particles include Al, Ba, B, Ca, Si, Sr, Mg, NiSi.₂And Si peritectic alloy, AlSb, CuMgSb, SiO, and AlN, and Ag, Sn, and Bi as a comparative example were supported on carbon.
[0027]
The chemical bonding between the carbon particles and the metal / alloy was performed as follows. A metal, alloy, oxide or nitride powder is fed into a high-frequency plasma of argon in a high-frequency magnetic field of 4 MHz, vaporized, and carbon particles (1) to (5) having an average particle diameter of 20 μm are introduced into the region. The powder of (2) is dispersed, and 5% by weight of ultrafine particles of metal, alloy, oxide or nitride having an average particle diameter of 0.1 μm are chemically bonded to the carbon particles by vapor pressure control. Al, Ba, B, Ca, Si, Sr, Mg, NiSi₂As for the peritectic alloy of Al and Si, AlSb, CuMgSb, SiO, and AlN, it was performed under the condition for forming a carbide at the carbon interface, and for Ag, Sn, and Bi, it was performed under the condition for simply supporting.
[0028]
The prepared sample was analyzed by X-ray diffraction and XPS (X-ray Photoelectron Spectroscopy).
[0029]
Carbon particles with Al, Ba, B, Ca, Si, Sr, Mg, NiSi₂And X, X-ray diffraction shows carbon, each metal or alloy or oxide or nitride, and carbon for particles in which a peritectic alloy of Si and Si, AlSb, CuMgSb, SiO, and AlN metal or alloy or oxide or nitride is combined. As carbides that are thought to be generated by reaction with particles, Al is Al._FourC_Three, Ba is BaC₂, B is B_FourFor C and Ca, CaC₂, Si for SiC, Sr for SrC₂, Mg for MgC₂NiSi₂SiC for Si and Si peritectic alloys, Al for AlSb_FourC_ThreeMgC for CuMgSb₂, SiC for SiO, Al for AlN_FourC_ThreeWas confirmed. Further, the chemical bonding state of the elements bonded to the carbon particles was examined by XPS analysis. As an example, in a sample in which Si having an average particle size of 0.1 μm was bonded to carbon particles having an average particle size of 20 μm by a thermal plasma method, the binding energy of Si 2p was 99.4 eV. Next, Si on the carbon particles was removed by about 0.09 μm by argon sputtering, and when measured in the same manner, two Si2p peaks appeared, 99.4 eV and 100.4 eV. The 99.4 eV reflects the Si 2p binding energy of the Si metal alone, and the 100.4 eV reflects the Si Si binding energy (refer to JEOL's Handbook of X-ray Photoelectron Spectroscopy Reference). by). That is, it can be seen that Si is bonded to the carbon particles by forming carbide SiC at the interface. In addition, other metals, alloys, oxides or nitrides were measured by the same method, and it was found that each formed a carbide at the interface of carbon particles as in Si, and was in a chemical bond state with carbon particles. It was.
[0030]
However, regarding Ag, Sn, and Bi, only one binding energy is observed even before the argon sputtering (Ag3d)._5/2: 368.2 eV, Sn3d_5/2: 484.87 eV, Bi4f_7/2157.8 eV), Ag, Sn, Bi supported on carbon particles are considered to be bonded without forming carbide at the interface with the carbon particles.
[0031]
As described above, the carbon particle powder in which a metal, an alloy, an oxide, or a nitride is chemically bonded or supported is used as the negative electrode active material.
[0032]
Next, a cylindrical battery was produced using the negative electrode material produced as described above, and battery characteristics were evaluated. FIG. 1 shows a longitudinal sectional view of a cylindrical battery using the negative electrode of the present invention. In FIG. 1, the positive electrode 1 is LiCoO as a positive electrode active material.₂A mixture of carbon black as a conductive material and an aqueous dispersion of polytetrafluoroethylene as a binder in a weight ratio of 100: 2.5: 7.5 is coated on both sides of an aluminum foil core material. After drying, rolling, and cutting to a predetermined size, the positive electrode lead plate 2 made of titanium was spot welded.
[0033]
The negative electrode 3 was prepared by using polyvinylidene fluoride as a binder and a carbon material (acetylene black, artificial graphite, spherical graphite, natural graphite, fibrous graphite, graphitizable carbon, A predetermined amount of a mixture obtained by mixing non-graphitizable carbon etc. in a weight ratio of 75: 20: 5 is applied to a copper foil core, dried, rolled, and then a predetermined size. The copper negative electrode lead plate 4 was spot-welded and cut. 5 is a separator made of a polypropylene resin microporous film, and the positive electrode 1 and the negative electrode 3 are spirally wound through the separator 5 to constitute an electrode plate group. An upper insulating plate 6 and a lower insulating plate 7 made of polypropylene resin are arranged above and below the electrode plate group, respectively, and inserted into a case 8 which is nickel-plated on iron. The positive electrode lead plate 2 is attached to a titanium sealing plate 9 and a negative electrode. After the lead plate 4 was spot welded to the bottom of the case 8, an electrolytic solution was injected, and the lead plate 4 was sealed through the gasket 10 to produce a battery.
[0034]
This battery has a diameter of 17 mm and a height of 50 mm. Reference numeral 11 denotes a positive terminal, and the case 8 serves as the negative terminal.
[0035]
The electrolyte is LiPF as the solute.₆Lithium salt of 1.5 mol / dm^Three Was dissolved in a 1: 1 mixed solvent of a high-viscosity organic solvent of EC and a low-viscosity organic solvent of DEC as a solvent.
[0036]
The negative electrode material of the battery embodying the present invention is made of Al, Ba, B, Ca, Si, Sr, Mg, NiSi on carbon.₂And Si peritectic alloy, AlSb, CuMgSb, SiO, and AlN are chemically bonded, and the comparative batteries are composed of the above-described carbon (1) to (5), as well as Ag, Sn, and Bi. The supported one was used.
[0037]
Each battery was evaluated by a constant current charge / discharge cycle test of 0.2C (1C charge / discharge corresponds to charge / discharge of 780 mAh in one hour). The charge upper limit voltage was 4.2V, and the discharge lower limit voltage was 3.0V. The results are shown in Table 1 as initial discharge capacity after 300 cycles and after 1000 cycles.
[0038]
[Table 1]

[0039]
From Table 1, the batteries using the negative electrode material in the examples of the present invention have higher discharge capacity in the first cycle for each carbon material (d (002) = 3.35-4.1 Å) than the comparative battery. It is capacity. In other words, the batteries 1, 2 and 3 in which the present invention is implemented are compared with the comparative batteries 4 and 5, and the batteries 6 and 7 in which the present invention is implemented are compared with the batteries 10 and 10 in which the present invention is implemented. 11 and 12, compared with comparative batteries 13 and 14, batteries 15 and 16 according to the present invention are compared with comparative batteries 17 and 18, and batteries 19 and 20 according to the present invention are compared with comparative batteries 21 and 22 in the first cycle. It can be seen that the discharge capacity is increased.
[0040]
Further, when comparing the discharge capacity at the 300th cycle, each battery embodying the present invention in which a metal, an alloy, an oxide or a nitride is bonded to carbon particles or carried is compared with a carbon-only comparative battery (Table 1 shows a large discharge capacity compared to the battery 1 in FIG.
[0041]
At the 1000th cycle, the batteries 1, 2, 3, 6, 7, 10, 11, 12, 15, 16, 19, and 20 in which the present invention is implemented still maintain a high capacity, and the cycle deteriorates. You can see that there is little. This is because the negative electrode material of the present invention forms a carbide by the reaction of carbon and metal or alloy or oxide or nitride at the interface of carbon particles, and the carbon particle and metal or alloy or oxide or nitride are chemically bonded. The strong bonding makes it possible to prevent the metal or alloy or oxide or nitride due to repeated charge and discharge from detaching from the carbon particles due to its own expansion and contraction. This is thought to be because the deterioration was suppressed to a small level. However, in the comparative batteries 5, 9, 14, 18, and 22 in which the metal is simply supported on the carbon particles, the discharge capacity is smaller than that of the comparative battery made of only carbon. The cause of this is thought to be that the supported metal has been separated from the electrode and inactivated due to the expansion and contraction of the supported metal due to the charge / discharge cycle. Further, it is considered that in the process of deterioration of the metal, some adverse effect is exerted on the carbon particles of the base material, and the discharge capacity is smaller than that of the comparative battery made of only the carbon particles.
[0042]
Judgment on safety is performed by charging and discharging a battery using each sample as a negative electrode material for 1000 cycles, and performing a TG-DTA thermal measurement of the negative electrode material taken out by disassembling the battery in a charged state from room temperature to 350 ° C. Safety was judged based on whether the temperature showing the maximum amount of heat within the temperature range was higher or lower than that of the negative electrode material made only of the carbon material.
[0043]
As a result, in the negative electrode material of the present invention, the temperature indicating the maximum value of heat was higher than that of the negative electrode material composed only of the carbon material. And in the negative electrode material which made the carbon particle only carry | support metal, the temperature which shows the maximum value of calorie was lower than the negative electrode material comprised only with the carbon material.
[0044]
Thus, it turns out that the negative electrode material of the present invention is also excellent in terms of safety.
[0045]
As described above, when the negative electrode material of the present invention is used for a non-aqueous electrolyte secondary battery, it has a higher capacity and is superior to a secondary battery using a material composed solely of carbon particles or a material obtained by simply supporting a metal on carbon particles. In addition, it is possible to provide a non-aqueous electrolyte secondary battery that exhibits excellent cycle characteristics and high safety.
[0046]
(Example 2)
Next, the carbon (1) in Example 1 was used, and the average particle diameter of the carbon (1) was sieved to 0.5 to 70 μm. The particles were chemically bonded by a thermal plasma method. At this time, it was confirmed by the X-ray diffraction and XPS analysis that SiC was formed at the carbon particle interface. Further, since the difference in the average particle size of the carbon particles caused a difference in the amount of Si chemically bonded, the amount of Si (weight ratio) with respect to the carbon particles having each average particle size was determined by chemical analysis. As a comparative example, carbon particles carrying 0 to 50% by weight of Ag (only carbon (1)) with an average particle size of 0.1 μm were used instead of Si. In the case of Ag loading, as in Example 1, carbon and Ag carbides were not observed at the carbon interface.
[0047]
Using these samples as the negative electrode active material, non-aqueous electrolyte secondary batteries were produced in the same manner as in Example 1. And evaluation of the battery performed 0.2C (1C charging / discharging is equivalent to charging and discharging of 780 mAh in 1 hour) constant current charging / discharging cycle test similarly to Example 1. FIG. Moreover, the charge upper limit voltage was 4.2V, and the discharge lower limit voltage was 3.0V. As a result, the discharge capacity at the initial stage, after 300 cycles, and after 1000 cycles is shown in Table 2.
[0048]
[Table 2]

[0049]
From Table 2 (A), the discharge capacity in the first cycle (initial stage) of the battery (batteries 23 to 26) in which the average particle diameter of carbon is in the range of 0.5 to 50 μm is high enough to exceed the theoretical capacity of graphite. I know that there is.
[0050]
In the batteries 27 and 28 (average particle diameters are 70 and 100 μm, respectively), the discharge capacity at the first cycle is produced only by the carbon (1) of the battery 35 of the comparative example shown in Table 2 (B) because of the small amount of Si. However, the discharge capacity after 1000 cycles is slightly smaller than that of a battery made of only carbon (1). The cause is considered to be that some amount of Si chemically bonded to carbon has some adverse effect on the cycle characteristics. In the case of the battery 23, the amount of Si chemically bonded to the carbon particles is 40% by weight with respect to the carbon particles. Therefore, the discharge capacity at the first cycle is 3243 mAh, but at the 1000th cycle, the discharge capacity is only carbon. It was smaller than the battery 35 of the comparative example shown in Table 2 (B). This is probably because the amount of Si occupying the whole negative electrode material is too large, so that the expansion and contraction of Si accompanying the charge / discharge cycle is increased, and the overvoltage is increased. Therefore, it can be seen that the average particle diameter of the carbon particles is 1 to 50 μm and exhibits excellent cycle characteristics.
[0051]
As a comparative example, when the average particle diameter of carbon in Table 2 (B) is 1 to 50 μm, the discharge capacity at the first cycle is larger than that of the battery 35 using only carbon (1), but after 1000 cycles, it becomes less than that. End up. This is because Ag is not strongly bonded to the carbon particles. Therefore, when the charge / discharge cycle is repeated, Ag is separated from the carbon particles due to expansion and contraction of Ag, and the Ag particles are inactivated, and the electrode plate is loosened. Therefore, it is considered that the discharge capacity of carbon itself has decreased.
[0052]
As for safety, as in Example 1, the battery using each sample as the negative electrode material was charged and discharged for 1000 cycles, the battery was disassembled in the charged state, and the TG-DTA measurement of the negative electrode material was performed from room temperature. Safety was judged by comparing the temperature showing the maximum value of the heat quantity within the temperature range of 350 ° C. with the temperature shown in the negative electrode material composed only of carbon.
[0053]
As a result, the temperature indicating the maximum value of the calorific value of the negative electrode material having an average particle diameter of carbon (1) of 1 to 100 μm (batteries 24 to 28) is higher than that of the carbon material alone, and the negative electrode material of the battery of the comparative example The temperature showing the maximum value of the amount of heat was lower than that of the negative electrode material made of only the carbon material.
[0054]
From the above, when the carbon particles in the negative electrode material of the present invention have an average particle diameter of 1 to 50 μm and the weight ratio of the metal or alloy bonded to the carbon particles to the carbon particles is 1 to 20 wt%, the capacity and cycle characteristics , It can be seen that it exhibits even better characteristics for safety.
[0055]
(Example 3)
Next, carbon (1) having an average particle diameter of 20 μm of Example 1 was used, and Si particles having an average particle diameter of 0.005 to 10 μm were bonded to the carbon (1) by a thermal plasma method. At this time, it was confirmed by the X-ray diffraction and XPS analysis that SiC was formed at the carbon particle interface. Moreover, what was carry | supported on Ag with an average particle diameter of 0.005-10 micrometers instead of Si was used as a comparative example. In Ag, as in Example 1, no carbide was observed at the carbon interface.
[0056]
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 using this sample as the negative electrode active material. The battery was evaluated in the same manner as in Example 1 by performing a constant current charge / discharge cycle test at 0.2C (1C charge / discharge corresponds to charge / discharge of 780 mAh in one hour), and the charge upper limit voltage was 4.2V. The discharge lower limit voltage was 3.0V. The results are shown in Table 3 (A) (related to Si) and Table 3 (B) (related to Ag as a comparative example) at the initial stage, after 300 cycles and after 1000 cycles.
[0057]
[Table 3]

[0058]
From Table 3 (A), the average particle size of Si bonded to the carbon particles is within the range of 0.005 to 10 μm, and the discharge capacity at the first cycle is the carbon of the battery 35 shown in Table 2 (B) (1). In the case of only (average particle size 20 μm), it becomes larger than (800 mAh), and when the average particle size of Si of batteries 40 and 41 is in the range of 2 to 10 μm, the discharge capacity at the 1000th cycle is extremely reduced to 500 mAh or less. Yes. This is because when the Si particles become 2 μm or more, the effect of forming a carbide at the interface between the carbon particles and Si to form a strong chemical bond is diminished, and metals and alloys are dropped from the carbon particles due to expansion and contraction. It is considered that cycle deterioration will occur.
[0059]
In the case where Ag is supported on the carbon particles of Table 3 (B), the discharge capacity at the first cycle is equal to or higher than the discharge capacity of the battery 35 of Table 2 (B) described above, but after 1000 cycles, all the averages described The particle size is about 500 mAh or less. The reason for this is that Ag is not strongly bonded to the carbon particles as in Example 2. Therefore, when the charge / discharge cycle is repeated, Ag separates from the carbon particles due to expansion and contraction of Ag, and the Ag particles are inactivated. In addition, the discharge capacity of the carbon particles is reduced due to electrode plate expansion, and the discharge capacity after 1000 cycles is considered to be less than that of graphite.
[0060]
Regarding safety, similarly to Example 1, the battery using each sample as a negative electrode material was charged and discharged for 1000 cycles, the battery was disassembled in a charged state, and the TG-DTA measurement of the negative electrode material was performed from room temperature to 350 ° C. Safety was judged by comparing the temperature showing the maximum amount of heat within the temperature range with the temperature shown in the negative electrode material composed only of carbon.
[0061]
As a result, the average particle diameter of Si was 0.01 to 1 μm, that is, the temperature indicating the maximum value of the calorific value of the negative electrode material of the batteries 37 to 39 was higher than that of the negative electrode material containing only the carbon material. However, the temperature showing the maximum value of the calorific value of the negative electrode material of the batteries 36, 40, 41, 42 to 47 was lower than that of the negative electrode material made of only the carbon material.
[0062]
The battery 36 is considered to have a relatively large specific surface area because the average particle size of Si is as small as 0.005 μm, and the temperature at which the maximum value of the heat is higher than that of the negative electrode material made of only the carbon material.
[0063]
In the batteries 40 and 41, the Si bonded to the carbon particles is large, and when the charge / discharge cycle is repeated as seen in large particles of metals and alloys, the Si becomes finer, the specific surface area becomes considerably large, and the maximum amount of heat is shown. It is considered that the temperature was higher than that of the negative electrode material made of only the carbon material.
[0064]
In the batteries 42 to 47, since the bond between the carbon particles and Ag is weak, when charging and discharging are repeated for 1000 cycles, the Ag is detached from the carbon particles while being bonded to lithium, thereby causing an increase in specific surface area. It is considered that the temperature at which the maximum amount of heat is obtained is higher than that of the negative electrode material made of only the carbon material.
[0065]
From the above, when the average particle diameter of the metal or alloy chemically bonded to the carbon particles in the negative electrode material of the present invention is 0.01 to 1 μm, it shows more excellent characteristics with respect to capacity, cycle characteristics, and safety. I understand that.
[0066]
Example 4
Next, carbon particles obtained by chemically bonding Si particles having an average particle diameter of 0.1 μm to the carbon (1) of Example 1 having an average particle diameter of 20 μm by a thermal plasma method (carbon particle interface by X-ray diffraction or EPMA analysis). A negative electrode plate using a mixture of acetylene black as a conductive material (in addition, the carbons shown in Example 1, all of which can be used as the conductive material). A cylindrical battery was produced.
[0067]
And evaluation of the battery performed 0.2C (1C charging / discharging is equivalent to charging and discharging of 780 mAh in 1 hour) constant current charging / discharging cycle test similarly to Example 1. FIG. The charge upper limit voltage was 4.2V, and the discharge lower limit voltage was 3.0V. As a result, the discharge capacity at the initial stage, after 300 cycles, and after 1000 cycles is shown in Table 4. In addition, a battery manufactured without a conductive material was also evaluated as a comparative example.
[0068]
[Table 4]

[0069]
From Table 4, the discharge capacity of the first cycle in the batteries 49 to 51 is slightly reduced by mixing the conductive material as compared with the battery 53 of the comparative example. It can be seen that the capacity is higher than that of the battery 53. This is thought to be due to the fact that, when a conductive material is added, the resistance component is directly reduced by improving the conductivity, and the discharge capacity maintenance rate is improved by reducing the overvoltage.
[0070]
However, the effect cannot be obtained if the conductive material is small as in the battery 48, and the capacity of the negative electrode material cannot be increased if the conductive material is large as in the battery 52.
[0071]
Regarding safety, similarly to Example 1, the battery using each sample as a negative electrode material was charged and discharged for 1000 cycles, the battery was disassembled in a charged state, and the TG-DTA measurement of the negative electrode material was performed from room temperature to 350 ° C. Safety was judged by comparing the temperature showing the maximum amount of heat within the temperature range with the temperature shown in the negative electrode material composed only of carbon.
[0072]
As a result, also in the batteries 48 to 52 and the battery 53 of the comparative example, the temperature indicating the maximum value of the calorific value of these negative electrode materials was higher than that of the negative electrode material containing only the carbon material.
[0073]
From the above, by including 5 to 80% by weight of carbon as a conductive material in the negative electrode material of the present invention, there is no problem in safety, and although the initial capacity is slightly reduced, battery characteristics with further excellent cycle characteristics can be obtained. I understand.
[0074]
Furthermore, when the negative electrode material of the present invention is used for a non-aqueous electrolyte secondary battery, the positive electrode active material includes Ti, Mo, W, Nb, V, Fe, in addition to the Co, Ni, Mn transition metal compound containing lithium. The same effect can be obtained by using compounds such as composite oxides and composite sulfides of one or more transition metals such as Cr and Cr. Especially for high voltage and high energy density, LiCoO₂, LiNiO₂, LiMn₂O_FourA positive electrode active material such as is preferable.
[0075]
And as a solvent of the electrolyte used for the nonaqueous electrolyte secondary battery in Examples 1-4, cyclic | annular, chain | strand carbonates, such as EC, PC, DMC, EMC, DEC, (gamma)-, such as (gamma) -butyrolactone, etc. Even if a solvent selected from lactones, chain carbonate ethers such as DME, DEE, and EME, cyclic ethers such as tetrahydrofuran, nitriles such as acetonitrile, or a mixture of two or more kinds of ECs is used. An effect equivalent to that obtained by mixing 1: 1 with DEC can be obtained. In particular, it is preferable to use a mixed solvent containing EC as an essential component.
[0076]
As the solute of the nonaqueous electrolyte, LiAsF₆, LiPF₆, LiAlCl_Four, LiClO_Four, LiCF_ThreeSO_Three, LiSbF₆, LiSCN, LiCl, LiC₆HSO_Three, Li (CF_ThreeSO₂)₂, LiC (CF_ThreeSO₂)_Three, C_FourF₆SO_ThreeEven if lithium salt such as Li and a mixture thereof are used, the LiPF of Example₆The same effect can be obtained.
[0077]
Regarding the shape of the battery, a cylindrical shape is used in the present embodiment, but a battery having a coin shape, a square shape, or any other shape can be used. The negative electrode active material of the present invention is also effective as a negative electrode active material for polymer batteries.
[0078]
  And claims4Or7The nonaqueous electrolyte secondary battery according to any one of the described inventions and any battery shape described above can be applied to a power source for driving a motor of a motorcycle or an electric vehicle.
[0079]
【The invention's effect】
  As described above, the present invention provides a carbon particle as a negative electrode material for a non-aqueous electrolyte secondary battery capable of occluding and releasing lithium.surfaceCan form an alloy with lithiumMetal, Carbon and itsWith metalofBy high frequency thermal plasmaCarbide formed by reactionby doing,By using a composite carbon material in a state of chemical bonding with carbon particles, a non-aqueous electrolyte secondary battery having high capacity, excellent cycle characteristics, and high safety can be realized.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a cylindrical battery using a negative electrode in one embodiment of the present invention.
[Explanation of symbols]
1 Positive electrode
2 Positive lead plate
3 Negative electrode
4 Negative lead plate
5 Separator
6 Upper insulation plate
7 Lower insulation plate
8 cases
9 Sealing plate
10 Gasket
11 Positive terminal

Claims (9)

On the surface of the carbon particles, the metal capable of forming an alloy with lithium forms a carbide by a reaction with carbon by high-frequency thermal plasma , so that the carbon particles and the metal are in a chemically bonded state, and the lithium and A metal capable of forming an alloy is a metal selected from the group consisting of Al, Ba, B, Ca, Si, Sr, and Mg, and a negative electrode material for a non-aqueous electrolyte secondary battery.   2. The negative electrode material for a non-aqueous electrolyte secondary battery according to claim 1, wherein the carbon particles have an interplanar spacing d (002) by X-ray diffraction of 3.35 to 4.1 mm.   The negative electrode material for a nonaqueous electrolyte secondary battery according to claim 1, wherein the carbon particles have an average particle diameter of 1 to 50 μm.   A nonaqueous electrolyte secondary battery having a nonaqueous electrolyte, a positive electrode, and a negative electrode capable of occluding and releasing lithium, comprising a negative electrode using the negative electrode material according to claim 1. Electrolyte secondary battery. The nonaqueous electrolyte secondary battery according to claim 4, comprising a negative electrode containing 5 to 80% by weight of carbon as a conductive material. The nonaqueous electrolyte secondary battery according to claim 4, comprising a positive electrode using a lithium-containing transition metal compound as a positive electrode active material. The nonaqueous electrolyte secondary battery according to claim 4, comprising a nonaqueous electrolyte in a state where a lithium salt is dissolved in a carbonate ester organic solvent. The nonaqueous electrolyte secondary battery according to any one of claims 4 to 7 , wherein the nonaqueous electrolyte secondary battery is used as a power source of a motor for driving a motorcycle. The nonaqueous electrolyte secondary battery according to any one of claims 4 to 7 , wherein the nonaqueous electrolyte secondary battery is used as a power source of a motor for driving an electric vehicle.

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