JP4710116B2 - Nonaqueous electrolyte and lithium secondary battery using the same - Google Patents

Description

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【化１１】

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（式中、Ｒ¹、Ｒ⁴、Ｒ⁵、Ｒ⁶、Ｒ⁷、Ｒ⁸、Ｒ⁹、Ｒ¹⁰、Ｒ¹¹、Ｒ¹²およびＲ¹⁷は、それぞれ独立して炭素数１〜１２のアルキル基、炭素数３〜６のシクロアルキル基、アリール基、または水素原子を示す。但し、Ｒ⁴、Ｒ⁵、Ｒ⁶およびＲ⁷が同時に水素原子となることはない。式中、Ｒ²、Ｒ³、Ｒ¹³、Ｒ¹⁴、Ｒ¹⁵およびＲ¹⁶は、それぞれ独立して炭素数１〜１２のアルキル基、炭素数３〜６のシクロアルキル基、アリール基を示す。また、Ｒ²とＲ³、Ｒ⁴とＲ⁵、Ｒ⁶とＲ⁷、Ｒ¹³とＲ¹⁴、Ｒ¹⁵とＲ¹⁶は、互いに結合して炭素数３〜６のシクロアルキル基を形成していても良い。式中、Ｙ¹は、−ＣＯＯＲ¹⁸、−ＣＯＲ¹⁸または−ＳＯ₂Ｒ¹⁸、Ｙ²は、−ＣＯＯＲ¹⁹、−ＣＯＲ¹⁹または−ＳＯ₂Ｒ¹⁹、Ｙ³は、−ＣＯＯＲ²⁰、−ＣＯＲ²⁰または−ＳＯ₂Ｒ²⁰、Ｙ⁴は、−ＣＯＯＲ²¹、−ＣＯＲ²¹または−ＳＯ₂Ｒ²¹、およびＹ⁵は、−ＣＯＯＲ²²、−ＣＯＲ²²、−ＳＯ₂Ｒ²²を示し、前記Ｒ¹⁸、Ｒ¹⁹、Ｒ²⁰、Ｒ²¹およびＲ²²は、それぞれ独立して炭素数１〜１２のアルキル基、炭素数３〜６のシクロアルキル基、アリール基を示す。ただし、ｎは１または２の整数を示す。）で表されるアルキン誘導体のうち少なくとも１種が電解液の重量に対して０．０１〜２０重量％含有されていることを特徴とするリチウム二次電池用電解液に関する。
【００１１】
また、本発明は、正極、負極および非水溶媒に電解質が溶解されている電解液からなるリチウム二次電池において、該電解液中に下記一般式（Ｉ）、（ＩＩ）、（ＩＩＩ）、（ＩＶ）、
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【００１６】
（式中、Ｒ¹、Ｒ⁴、Ｒ⁵、Ｒ⁶、Ｒ⁷、Ｒ⁸、Ｒ⁹、Ｒ¹⁰、Ｒ¹¹、Ｒ¹²およびＲ¹⁷は、それぞれ独立して炭素数１〜１２のアルキル基、炭素数３〜６のシクロアルキル基、アリール基、または水素原子を示す。但し、Ｒ⁴、Ｒ⁵、Ｒ⁶およびＲ⁷が同時に水素原子となることはない。式中、Ｒ²、Ｒ³、Ｒ¹³、Ｒ¹⁴、Ｒ¹⁵およびＲ¹⁶は、それぞれ独立して炭素数１〜１２のアルキル基、炭素数３〜６のシクロアルキル基、アリール基を示す。また、Ｒ²とＲ³、Ｒ⁴とＲ⁵、Ｒ⁶とＲ⁷、Ｒ¹³とＲ¹⁴、Ｒ¹⁵とＲ¹⁶は、互いに結合して炭素数３〜６のシクロアルキル基を形成していても良い。式中、Ｙ¹は、−ＣＯＯＲ¹⁸、−ＣＯＲ¹⁸または−ＳＯ₂Ｒ¹⁸、Ｙ²は、−ＣＯＯＲ¹⁹、−ＣＯＲ¹⁹または−ＳＯ₂Ｒ¹⁹、Ｙ³は、−ＣＯＯＲ²⁰、−ＣＯＲ²⁰または−ＳＯ₂Ｒ²⁰、Ｙ⁴は、−ＣＯＯＲ²¹、−ＣＯＲ²¹または−ＳＯ₂Ｒ²¹、およびＹ⁵は、−ＣＯＯＲ²²、−ＣＯＲ²²、−ＳＯ₂Ｒ²²を示し、前記Ｒ¹⁸、Ｒ¹⁹、Ｒ²⁰、Ｒ²¹およびＲ²²は、それぞれ独立して炭素数１〜１２のアルキル基、炭素数３〜６のシクロアルキル基、アリール基を示す。ただし、ｎは１または２の整数を示す。）で表されるアルキン誘導体のうち少なくとも１種が電解液の重量に対して０．０１〜２０重量％含有されていることを特徴とするリチウム二次電池に関する。
【００１７】
電解液中に含有される前記アルキン誘導体は、充電時に炭素負極表面で、電解液中の有機溶媒より先に還元分解して、該分解物の一部は、天然黒鉛や人造黒鉛などの活性で高結晶化した炭素負極表面に不働態皮膜を形成することにより、電解液中の有機溶媒の還元分解を未然に防ぐと推定される。
さらに、該分解物の一部は、正極材料表面の電位が過度に高くなった微少な過電圧部分において、電解液中の有機溶媒より先に酸化分解して、電解液中の有機溶媒の酸化分解を未然に防ぐと推定される。
これにより、電池の正常な反応を損なうことなく電解液の分解を抑制する効果を有するものと考えられる。
【００１８】
【発明の実施の形態】
非水溶媒に電解質が溶解されている電解液に含有される前記一般式（Ｉ）、（ＩＩ）、（ＩＩＩ），（ＩＶ）で表されるアルキン誘導体において、Ｒ¹、Ｒ⁴、Ｒ⁵、Ｒ⁶、Ｒ⁷、Ｒ⁸、Ｒ⁹、Ｒ¹⁰、Ｒ¹¹、Ｒ¹²およびＲ¹⁷は、それぞれ独立してメチル基、エチル基、プロピル基、ブチル基、ペンチル基、ヘキシル基のような炭素数１〜１２のアルキル基が好ましい。アルキル基はイソプロピル基、イソブチル基のような分枝アルキル基でもよい。また、シクロプロピル基、シクロヘキシル基のような炭素数３〜６のシクロアルキル基でもよい。また、フェニル基、ベンジル基、ｐ−トリル基のような炭素数６〜１２のアリール基を含有するものでもよい。さらに、水素原子でもよい。但し、Ｒ⁴、Ｒ⁵、Ｒ⁶およびＲ⁷が同時に水素原子となることはない。式中、Ｒ²、Ｒ³、Ｒ¹³、Ｒ¹⁴、Ｒ¹⁵およびＲ¹⁶は、それぞれ独立してメチル基、エチル基、プロピル基、ブチル基、ペンチル基、ヘキシル基のような炭素数１〜１２のアルキル基が好ましい。アルキル基はイソプロピル基、イソブチル基のような分枝アルキル基でもよい。また、シクロプロピル基、シクロヘキシル基のような炭素数３〜６のシクロアルキル基でもよい。また、フェニル基、ベンジル基、ｐ−トリル基のような炭素数６〜１２のアリール基を含有するものでもよい。
【００１９】
また、前記一般式（Ｉ）、（ＩＩ）、（ＩＩＩ）で表されるアルキン誘導体におけるＹ¹、Ｙ²、Ｙ³、Ｙ⁴およびＹ⁵において、Ｒ¹⁸、Ｒ¹⁹、Ｒ²⁰、Ｒ²¹およびＲ²²は、それぞれ独立してメチル基、エチル基、プロピル基、ブチル基、ペンチル基、ヘキシル基のような炭素数１〜１２のアルキル基が好ましい。アルキル基はイソプロピル基、イソブチル基のような分枝アルキル基でもよい。また、シクロプロピル基、シクロヘキシル基のような炭素数３〜６のシクロアルキル基でもよい。また、フェニル基、ベンジル基、ｐ−トリル基のような炭素数６〜１２のアリール基を含有するものでもよい。また、Ｒ²とＲ³、Ｒ⁴とＲ⁵、Ｒ⁶とＲ⁷、Ｒ¹³とＲ¹⁴、Ｒ¹⁵とＲ¹⁶は、互いに結合してシクロプロピル基、シクロブチル基、シクロペンチル基、シクロヘキシル基を形成していても良い。
ただし、ｎは１または２の整数を示す。
【００２０】
前記一般式（Ｉ）で表されるアルキン誘導体の具体例として、例えば、Ｙ¹＝−ＣＯＯＲ¹⁸の場合、１，１−ジメチル−２−プロピニルメチルカーボネート〔Ｒ¹＝水素原子、Ｒ²＝Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、１，１−ジエチル−２−プロピニルメチルカーボネート〔Ｒ¹＝水素原子、Ｒ²＝Ｒ³＝エチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、１，１−エチルメチル−２−プロピニルメチルカーボネート〔Ｒ¹＝水素原子、Ｒ²＝エチル基、Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、１，１−イソブチルメチル−２−プロピニルメチルカーボネート〔Ｒ¹＝水素原子、Ｒ²＝イソブチル基、Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、１，１−ジメチル−２−ブチニルメチルカーボネート〔Ｒ¹＝Ｒ²＝Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、１−エチニルシクロヘキシルメチルカーボネート〔Ｒ¹＝水素原子、Ｒ²とＲ³が結合＝ペンタメチレン基、Ｒ¹⁸＝メチル基、ｎ＝１〕、１，１−フェニルメチル−２−プロピニルメチルカーボネート〔Ｒ¹＝水素原子、Ｒ²＝フェニル基、Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、１，１−ジフェニル−２−プロピニルメチルカーボネート〔Ｒ¹＝水素原子、Ｒ²＝Ｒ³＝フェニル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、１，１−ジメチル−２−プロピニルエチルカーボネート〔Ｒ¹＝水素原子、Ｒ²＝Ｒ³＝メチル基、Ｒ¹⁸＝エチル基、ｎ＝１〕などが挙げられる。Ｙ¹＝−ＣＯＲ¹⁸の場合、酢酸１，１−ジメチル−２−プロピニル〔Ｒ¹＝水素原子、Ｒ²＝Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、酢酸１，１−ジエチル−２−プロピニル〔Ｒ¹＝水素原子、Ｒ²＝Ｒ³＝エチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、酢酸１，１−エチルメチル−２−プロピニル〔Ｒ¹＝水素原子、Ｒ²＝エチル基、Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、酢酸１，１−イソブチルメチル−２−プロピニル〔Ｒ¹＝水素原子、Ｒ²＝イソブチル基、Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、酢酸１，１−ジメチル−２−ブチニル〔Ｒ¹＝Ｒ²＝Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、酢酸１−エチニルシクロヘキシル〔Ｒ¹＝水素原子、Ｒ²とＲ³が結合＝ペンタメチレン基、Ｒ¹⁸＝メチル基、ｎ＝１〕、酢酸１，１−フェニルメチル−２−プロピニル〔Ｒ¹＝水素原子、Ｒ²＝フェニル基、Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、酢酸１，１−ジフェニル−２−プロピニル〔Ｒ¹＝水素原子、Ｒ²＝Ｒ³＝フェニル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、プロピオン酸１，１−ジメチル−２−プロピニル〔Ｒ¹＝水素原子、Ｒ²＝Ｒ³＝メチル基、Ｒ¹⁸＝エチル基、ｎ＝１〕などが挙げられる。Ｙ¹＝−ＳＯ₂Ｒ¹⁸の場合、メタンスルホン酸１，１−ジメチル−２−プロピニル〔Ｒ¹＝水素原子、Ｒ²＝Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、メタンスルホン酸１，１−ジエチル−２−プロピニル〔Ｒ¹＝水素原子、Ｒ²＝Ｒ³＝エチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、メタンスルホン酸１，１−エチルメチル−２−プロピニル〔Ｒ¹＝水素原子、Ｒ²＝エチル基、Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、メタンスルホン酸１，１−イソブチルメチル−２−プロピニル〔Ｒ¹＝水素原子、Ｒ²＝イソブチル基、Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、メタンスルホン酸１，１−ジメチル−２−ブチニル〔Ｒ¹＝Ｒ²＝Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、メタンスルホン酸１−エチニルシクロヘキシル〔Ｒ¹＝水素原子、Ｒ²とＲ³が結合＝ペンタメチレン基、Ｒ¹⁸＝メチル基、ｎ＝１〕、メタンスルホン酸１，１−フェニルメチル−２−プロピニル〔Ｒ¹＝水素原子、Ｒ²＝フェニル基、Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、メタンスルホン酸１，１−ジフェニル−２−プロピニル〔Ｒ¹＝水素原子、Ｒ²＝Ｒ³＝フェニル基、Ｒ¹⁸＝メチル基、ｎ＝１〕、エタンスルホン酸１，１−ジメチル−２−プロピニル〔Ｒ¹＝水素原子、Ｒ²＝Ｒ³＝メチル基、Ｒ¹⁸＝エチル基、ｎ＝１〕などが挙げられる。ただし、本発明はこれらの化合物に何ら限定されるものではない。
【００２１】
前記一般式（ＩＩ）で表されるアルキン誘導体の具体例として、例えば、Ｙ²＝−ＣＯＯＲ¹⁹およびＹ³＝−ＣＯＯＲ²⁰の場合、３−ヘキシン−２，５−ジオール ジメチルジカーボネート〔Ｒ⁴＝Ｒ⁶＝メチル基、Ｒ⁵＝Ｒ⁷＝水素原子、Ｒ¹⁹＝Ｒ²⁰＝メチル基、ｎ＝１〕、３−ヘキシン−２，５−ジオール ジエチルジカーボネート〔Ｒ⁴＝Ｒ⁶＝メチル基、Ｒ⁵＝Ｒ⁷＝水素原子、Ｒ¹⁹＝Ｒ²⁰＝エチル基、ｎ＝１〕、２，５−ジメチル−３−ヘキシン−２，５−ジオール ジメチルジカーボネート〔Ｒ⁴＝Ｒ⁵＝Ｒ⁶＝Ｒ⁷＝メチル基、Ｒ¹⁹＝Ｒ²⁰＝メチル基、ｎ＝１〕、２，５−ジメチル−３−ヘキシン−２，５−ジオール ジエチルジカーボネート〔Ｒ⁴＝Ｒ⁵＝Ｒ⁶＝Ｒ⁷＝メチル基、Ｒ¹⁹＝Ｒ²⁰＝エチル基、ｎ＝１〕などが挙げられる。Ｙ²＝−ＣＯＲ¹⁹およびＹ³＝−ＣＯＲ²⁰の場合、３−ヘキシン−２，５−ジオール ジアセテート〔Ｒ⁴＝Ｒ⁶＝メチル基、Ｒ⁵＝Ｒ⁷＝水素原子、Ｒ¹⁹＝Ｒ²⁰＝メチル基、ｎ＝１〕、３−ヘキシン−２，５−ジオール ジプロピオネート〔Ｒ⁴＝Ｒ⁶＝メチル基、Ｒ⁵＝Ｒ⁷＝水素原子、Ｒ¹⁹＝Ｒ²⁰＝エチル基、ｎ＝１〕、２，５−ジメチル−３−ヘキシン−２，５−ジオール ジアセテート〔Ｒ⁴＝Ｒ⁵＝Ｒ⁶＝Ｒ⁷＝メチル基、Ｒ¹⁹＝Ｒ²⁰＝メチル基、ｎ＝１〕、２，５−ジメチル−３−ヘキシン−２，５−ジオール ジプロピオネート〔Ｒ⁴＝Ｒ⁵＝Ｒ⁶＝Ｒ⁷＝メチル基、Ｒ¹⁹＝Ｒ²⁰＝エチル基、ｎ＝１〕などが挙げられる。Ｙ²＝−ＳＯ₂Ｒ¹⁹およびＹ³＝−ＳＯ₂Ｒ²⁰の場合、３−ヘキシン−２，５−ジオールジメタンスルホネート〔Ｒ⁴＝Ｒ⁶＝メチル基、Ｒ⁵＝Ｒ⁷＝水素原子、Ｒ¹⁹＝Ｒ²⁰＝メチル基、ｎ＝１〕、３−ヘキシン−２，５−ジオール ジエタンスルホネート〔Ｒ⁴＝Ｒ⁶＝メチル基、Ｒ⁵＝Ｒ⁷＝水素原子、Ｒ¹⁹＝Ｒ²⁰＝エチル基、ｎ＝１〕、２，５−ジメチル−３−ヘキシン−２，５−ジオール ジメタンスルホネート〔Ｒ⁴＝Ｒ⁵＝Ｒ⁶＝Ｒ⁷＝メチル基、Ｒ¹⁹＝Ｒ²⁰＝メチル基、ｎ＝１〕、２，５−ジメチル−３−ヘキシン−２，５−ジオール ジエタンスルホネート〔Ｒ⁴＝Ｒ⁵＝Ｒ⁶＝Ｒ⁷＝メチル基、Ｒ¹⁹＝Ｒ²⁰＝エチル基、ｎ＝１〕などが挙げられる。ただし、本発明はこれらの化合物に何ら限定されるものではない。
【００２２】
前記一般式（ＩＩＩ）で表されるアルキン誘導体の具体例として、例えば、Ｙ⁴＝−ＣＯＯＲ²¹およびＹ⁵＝−ＣＯＯＲ²²の場合、２，４−ヘキサジイン−１，６−ジオール ジメチルジカーボネート〔Ｒ⁸＝Ｒ⁹＝Ｒ¹⁰＝Ｒ¹¹＝水素原子、Ｒ²¹＝Ｒ²²＝メチル基、ｎ＝１〕、２，４−ヘキサジイン−１，６−ジオール ジエチルジカーボネート〔Ｒ⁸＝Ｒ⁹＝Ｒ¹⁰＝Ｒ¹¹＝水素原子、Ｒ²¹＝Ｒ²²＝エチル基、ｎ＝１〕、２，７−ジメチル−３，５−オクタジイン−２，７−ジオール ジメチルジカーボネート〔Ｒ⁸＝Ｒ⁹＝Ｒ¹⁰＝Ｒ¹¹＝メチル基、Ｒ²¹＝Ｒ²²＝メチル基、ｎ＝１〕、２，７−ジメチル−３，５−オクタジイン−２，７−ジオールジエチルジカーボネート〔Ｒ⁸＝Ｒ⁹＝Ｒ¹⁰＝Ｒ¹¹＝メチル基、Ｒ²¹＝Ｒ²²＝エチル基、ｎ＝１〕などが挙げられる。Ｙ⁴＝−ＣＯＲ²¹およびＹ⁵＝−ＣＯＲ²²の場合、２，４−ヘキサジイン−１，６−ジオール ジアセテート〔Ｒ⁸＝Ｒ⁹＝Ｒ¹⁰＝Ｒ¹¹＝水素原子、Ｒ²¹＝Ｒ²²＝メチル基、ｎ＝１〕、２，４−ヘキサジイン−１，６−ジオール ジプロピオネート〔Ｒ⁸＝Ｒ⁹＝Ｒ¹⁰＝Ｒ¹¹＝水素原子、Ｒ²¹＝Ｒ²²＝エチル基、ｎ＝１〕、２，７−ジメチル−３，５−オクタジイン−２，７−ジオール ジアセテート〔Ｒ⁸＝Ｒ⁹＝Ｒ¹⁰＝Ｒ¹¹＝メチル基、Ｒ²¹＝Ｒ²²＝メチル基、ｎ＝１〕、２，７−ジメチル−３，５−オクタジイン−２，７−ジオール ジプロピオネート〔Ｒ⁸＝Ｒ⁹＝Ｒ¹⁰＝Ｒ¹¹＝メチル基、Ｒ²¹＝Ｒ²²＝エチル基、ｎ＝１〕などが挙げられる。Ｙ⁴＝−ＳＯ₂Ｒ²¹およびＹ⁵＝−ＳＯ₂Ｒ²²の場合、２，４−ヘキサジイン−１，６−ジオール ジメタンスルホネート〔Ｒ⁸＝Ｒ⁹＝Ｒ¹⁰＝Ｒ¹¹＝水素原子、Ｒ²¹＝Ｒ²²＝メチル基、ｎ＝１〕、２，４−ヘキサジイン−１，６−ジオール ジエタンスルホネート〔Ｒ⁸＝Ｒ⁹＝Ｒ¹⁰＝Ｒ¹¹＝水素原子、Ｒ²¹＝Ｒ²²＝エチル基、ｎ＝１〕、２，７−ジメチル−３，５−オクタジイン−２，７−ジオール ジメタンスルホネート〔Ｒ⁸＝Ｒ⁹＝Ｒ¹⁰＝Ｒ¹¹＝メチル基、Ｒ²¹＝Ｒ²²＝メチル基、ｎ＝１〕、２，７−ジメチル−３，５−オクタジイン−２，７−ジオール ジエタンスルホネート〔Ｒ⁸＝Ｒ⁹＝Ｒ¹⁰＝Ｒ¹¹＝メチル基、Ｒ²¹＝Ｒ²²＝エチル基、ｎ＝１〕などが挙げられる。ただし、本発明はこれらの化合物に何ら限定されるものではない。
【００２３】
前記一般式（ＩＶ）で表されるアルキン誘導体の具体例としては、例えば、ジ（１，１−ジメチル−２−プロピニル）カーボネート〔Ｒ¹²＝Ｒ¹⁷＝水素原子、Ｒ¹³＝Ｒ¹⁴＝Ｒ¹⁵＝Ｒ¹⁶＝メチル基、ｎ＝１〕、ジ（１，１−ジエチル−２−プロピニル）カーボネート〔Ｒ¹²＝Ｒ¹⁷＝水素原子、Ｒ¹³＝Ｒ¹⁴＝Ｒ¹⁵＝Ｒ¹⁶＝エチル基、ｎ＝１〕、ジ（１，１−エチルメチル−２−プロピニル）カーボネート〔Ｒ¹²＝Ｒ¹⁷＝水素原子、Ｒ¹³＝Ｒ¹⁵＝エチル基、Ｒ¹⁴＝Ｒ¹⁶＝メチル基、ｎ＝１〕、ジ（１，１−イソブチルメチル−２−プロピニル）カーボネート〔Ｒ¹²＝Ｒ¹⁷＝水素原子、Ｒ¹³＝Ｒ¹⁵＝イソブチル基、Ｒ¹⁴＝Ｒ¹⁶＝メチル基、ｎ＝１〕、ジ（１，１−ジメチル−２−ブチニル）カーボネート〔Ｒ¹²＝Ｒ¹⁷＝Ｒ¹³＝Ｒ¹⁴＝Ｒ¹⁵＝Ｒ¹⁶＝メチル基、ｎ＝１〕、ジ（１−エチニルシクロヘキシル）カーボネート〔Ｒ¹²＝Ｒ¹⁷＝水素原子、Ｒ¹³とＲ¹⁴が結合＝ペンタメチレン基、Ｒ¹⁵とＲ¹⁶が結合＝ペンタメチレン基、ｎ＝１〕が挙げられる。ただし、本発明はこれらの化合物に何ら限定されるものではない。
【００２４】
前記アルキン誘導体において、前記一般式（Ｉ）、（ＩＩ）、（ＩＩＩ）、（ＩＶ）で表されるアルキン誘導体の含有量は、過度に多いと、電解液の電導度などが変わり電池性能が低下することがあり、また、過度に少ないと、十分な皮膜が形成されず、期待した電池特性が得られないので、電解液の重量に対して０．０１〜２０重量％、特に０．１〜１０重量％の範囲が好ましい。
【００２５】
本発明で使用される非水溶媒としては、高誘電率溶媒と低粘度溶媒とからなるものが好ましい。
高誘電率溶媒としては、例えば、エチレンカーボネート（ＥＣ）、プロピレンカーボネート（ＰＣ）、ブチレンカーボネート（ＢＣ）、ビニレンカーボネート（ＶＣ）などの環状カーボネート類が好適に挙げられる。これらの高誘電率溶媒は、１種類で使用してもよく、また２種類以上組み合わせて使用してもよい。
【００２６】
低粘度溶媒としては、例えば、ジメチルカーボネート（ＤＭＣ）、メチルエチルカーボネート（ＭＥＣ）、ジエチルカーボネート（ＤＥＣ）などの鎖状カーボネート類、テトラヒドロフラン、２−メチルテトラヒドロフラン、１，４−ジオキサン、１，２−ジメトキシエタン、１，２−ジエトキシエタン、１，２−ジブトキシエタンなどのエーテル類、γ−ブチロラクトンなどのラクトン類、アセトニトリルなどのニトリル類、プロピオン酸メチルなどのエステル類、ジメチルホルムアミドなどのアミド類が挙げられる。これらの低粘度溶媒は１種類で使用してもよく、また２種類以上組み合わせて使用してもよい。
高誘電率溶媒と低粘度溶媒とはそれぞれ任意に選択され組み合わせて使用される。なお、前記の高誘電率溶媒および低粘度溶媒は、容量比（高誘電率溶媒：低粘度溶媒）で通常１：９〜４：１、好ましくは１：４〜７：３の割合で使用される。
【００２７】
本発明で使用される電解質としては、例えば、ＬｉＰＦ₆、ＬｉＢＦ₄、ＬｉＣｌＯ₄、ＬｉＮ（ＳＯ₂ＣＦ₃）₂、ＬｉＮ（ＳＯ₂Ｃ₂Ｆ₅）₂、ＬｉＣ（ＳＯ₂ＣＦ₃）₃、ＬｉＰＦ₄（ＣＦ₃）₂、ＬｉＰＦ₃（Ｃ₂Ｆ₅）₃、ＬｉＰＦ₃（ＣＦ₃）₃、ＬｉＰＦ₃（ｉｓｏ−Ｃ₃Ｆ₇）₃、ＬｉＰＦ₅（ｉｓｏ−Ｃ₃Ｆ₇）などが挙げられる。これらの電解質は、１種類で使用してもよく、２種類以上組み合わせて使用してもよい。これら電解質は、前記の非水溶媒に通常０．１〜３Ｍ、好ましくは０．５〜１．５Ｍの濃度で溶解されて使用される。
【００２８】
本発明の電解液は、例えば、前記の高誘電率溶媒や低粘度溶媒を混合し、これに前記の電解質を溶解し、前記一般式（Ｉ）、（ＩＩ）、（ＩＩＩ）、（ＩＶ）で表されるアルキン誘導体のうち少なくとも１種を溶解することにより得られる。
【００２９】
本発明の電解液は、二次電池の構成部材、特にリチウム二次電池の構成部材として好適に使用される。二次電池を構成する電解液以外の構成部材については特に限定されず、従来使用されている種々の構成部材を使用できる。
【００３０】
例えば、正極活物質としてはコバルト、マンガン、ニッケル、クロム、鉄およびバナジウムからなる群より選ばれる少なくとも１種類の金属とリチウムとの複合金属酸化物が使用される。このような複合金属酸化物としては、例えば、ＬｉＣｏＯ₂、ＬｉＭｎ₂Ｏ₄、ＬｉＮｉＯ₂などが挙げられる。
【００３１】
正極は、前記の正極活物質をアセチレンブラック、カーボンブラックなどの導電剤およびポリテトラフルオロエチレン（ＰＴＦＥ）、ポリフッ化ビニリデン（ＰＶＤＦ）、スチレンとブタジエンの共重合体（ＳＢＲ）、アクリロニトリルとブタジエンの共重合体（ＮＢＲ）、カルボキシメチルセルロース（ＣＭＣ）などの結着剤と混練して正極合剤とした後、この正極材料を集電体としてのアルミニウムやステンレス製の箔やラス板に圧延して、５０℃〜２５０℃程度の温度で２時間程度真空下で加熱処理することにより作製される。
【００３２】
負極（負極活物質）としては、リチウム金属やリチウム合金、およびリチウムを吸蔵・放出可能な黒鉛型結晶構造を有する炭素材料〔熱分解炭素類、コークス類、グラファイト類（人造黒鉛、天然黒鉛など）、有機高分子化合物燃焼体、炭素繊維〕や複合スズ酸化物などの物質が使用される。特に、格子面（００２）の面間隔（ｄ₀₀₂）が０．３３５〜０．３４０ｎｍ（ナノメーター）である黒鉛型結晶構造を有する炭素材料を使用することが好ましい。なお、炭素材料のような粉末材料はエチレンプロピレンジエンターポリマー（ＥＰＤＭ）、ポリテトラフルオロエチレン（ＰＴＦＥ）、ポリフッ化ビニリデン（ＰＶＤＦ）、スチレンとブタジエンの共重合体（ＳＢＲ）、アクリロニトリルとブタジエンの共重合体（ＮＢＲ）、カルボキシメチルセルロース（ＣＭＣ）などの結着剤と混練して負極合剤として使用される。
【００３３】
リチウム二次電池の構造は特に限定されるものではなく、単層又は複層の正極、負極、セパレータを有するコイン型電池やポリマー電池、さらに、ロール状の正極、負極およびロール状のセパレータを有する円筒型電池や角型電池などが一例として挙げられる。なお、セパレータとしては公知のポリオレフィンの微多孔膜、織布、不織布などが使用される。
【００３４】
【実施例】
次に、実施例および比較例を挙げて、本発明を具体的に説明する。
実施例１
〔電解液の調製〕
ＥＣ／ＤＥＣ（容量比）＝１／２の非水溶媒を調製し、これにＬｉＰＦ₆を１Ｍの濃度になるように溶解して電解液を調製した後、さらにアルキン誘導体として１，１−ジメチル−２−プロピニルメチルカーボネート〔一般式（Ｉ）中、Ｙ¹＝−ＣＯＯＲ¹⁸、Ｒ¹＝水素原子、Ｒ²＝Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕を電解液に対して２重量％となるように加えた。
【００３５】
〔リチウム二次電池の作製および電池特性の測定〕
ＬｉＣｏＯ₂（正極活物質）を８０重量％、アセチレンブラック（導電剤）を１０重量％、ポリフッ化ビニリデン（結着剤）を１０重量％の割合で混合し、これに１−メチル−２−ピロリドンを加えてスラリー状にしてアルミ箔上に塗布した。その後、これを乾燥し、加圧成形して正極を調製した。人造黒鉛（負極活物質）を９０重量％、ポリフッ化ビニリデン（結着剤）を１０重量％の割合で混合し、これに１−メチル−２−ピロリドンを加えてスラリー状にして銅箔上に塗布した。その後、これを乾燥し、加圧成形して負極を調製した。そして、ポリプロピレン微多孔性フィルムのセパレータを用い、上記の電解液を注入してコイン電池（直径２０ｍｍ、厚さ３．２ｍｍ）を作製した。
このコイン電池を用いて、室温（２０℃）下、０．８ｍＡの定電流及び定電圧で、終止電圧４．２Ｖまで５時間で充電し、次に０．８ｍＡの定電流下、終止電圧２．７Ｖまで放電し、この充放電を繰り返した。初期放電容量は、１Ｍ ＬｉＰＦ₆＋ＥＣ／ＤＥＣ（容量比）＝１／２を電解液として用いた場合（比較例１）と比較してその相対容量として算出し、１．０３であった。５０サイクル後の電池特性を測定したところ、初期放電容量を１００％としたときの放電容量維持率は９２．２％であった。また、低温特性も良好であった。コイン電池の作製条件および電池特性を表１に示す。
【００３６】
実施例２
ＥＣ／ＤＥＣ（容量比）＝１／２の非水溶媒を調製し、これにＬｉＰＦ₆を１Ｍの濃度になるように溶解して電解液を調製した後、さらにアルキン誘導体として酢酸１，１−エチルメチル−２−プロピニル〔一般式（Ｉ）中、Ｙ¹＝−ＣＯＲ¹⁸、Ｒ¹＝水素原子、Ｒ²＝エチル基、Ｒ³＝メチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕を電解液に対して２重量％となるように加えた。この電解液を使用して実施例１と同様にコイン電池を作製し、電池特性を測定したところ、初期放電容量は、１Ｍ ＬｉＰＦ₆＋ＥＣ／ＤＥＣ（容量比）＝１／２を電解液として用いた場合（比較例１）と比較してその相対容量として算出し、１．０２であった。５０サイクル後の電池特性を測定したところ、初期放電容量を１００％としたときの放電容量維持率は９１．５％であった。コイン電池の作製条件および電池特性を表１に示す。
【００３７】
実施例３
ＰＣ／ＥＣ／ＤＥＣ（容量比）＝１／２／７の非水溶媒を調製し、これにＬｉＰＦ₆を１Ｍの濃度になるように溶解して電解液を調製した後、さらにアルキン誘導体としてメタンスルホン酸１，１−ジエチル−２−プロピニル〔一般式（Ｉ）中、Ｙ¹＝−ＳＯ₂Ｒ¹⁸、Ｒ¹＝水素原子、Ｒ²＝Ｒ³＝エチル基、Ｒ¹⁸＝メチル基、ｎ＝１〕を電解液に対して２重量％使用したほかは実施例１と同様に電解液を調製してコイン電池を作製し、電池特性を測定したところ、初期放電容量の相対容量は１．０５であり、５０サイクル後の電池特性を測定したところ、放電容量維持率は９１．９％であった。また、低温特性も良好であった。コイン電池の作製条件および電池特性を表１に示す。
【００３８】
実施例４
アルキン誘導体として２，５−ジメチル−３−ヘキシン−２，５−ジオール ジエチルジカーボネート〔一般式（ＩＩ）中、Ｙ²＝Ｙ³＝−ＣＯＯＲ¹⁹＝−ＣＯＯＲ²⁰、Ｒ⁴＝Ｒ⁵＝Ｒ⁶＝Ｒ⁷＝メチル基、Ｒ¹⁹＝Ｒ²⁰＝エチル基、ｎ＝１〕を電解液に対して１重量％使用したほかは実施例３と同様にコイン電池を作製し、電池特性を測定したところ、初期放電容量の相対容量は１．０２であり、５０サイクル後の電池特性を測定したところ、放電容量維持率は９１．１％であった。また、低温特性も良好であった。コイン電池の作製条件および電池特性を表１に示す。
【００３９】
実施例５
アルキン誘導体として３−ヘキシン−２，５−ジオール ジメタンスルホネート〔一般式（ＩＩ）中、Ｙ²＝Ｙ³＝−ＳＯ₂Ｒ¹⁹＝−ＳＯ₂Ｒ²⁰、Ｒ⁴＝Ｒ⁶＝メチル基、Ｒ⁵＝Ｒ⁷＝水素原子、Ｒ¹⁹＝Ｒ²⁰＝メチル基、ｎ＝１〕を電解液に対して１重量％使用したほかは実施例３と同様にコイン電池を作製し、電池特性を測定したところ、初期放電容量の相対容量は１．０３であり、５０サイクル後の電池特性を測定したところ、放電容量維持率は９１．６％であった。また、低温特性も良好であった。コイン電池の作製条件および電池特性を表１に示す。
【００４０】
実施例６
ＰＣ／ＥＣ／ＭＥＣ（容量比）＝１／２／７の非水溶媒を調製し、これにＬｉＰＦ₆を１Ｍの濃度になるように溶解して電解液を調製した後、さらにアルキン誘導体として２，４−ヘキサジイン−１，６−ジオール ジメチルジカーボネート〔一般式（ＩＩＩ）中、Ｙ⁴＝Ｙ⁵＝−ＣＯＯＲ²¹＝−ＣＯＯＲ²²、Ｒ⁸＝Ｒ⁹＝Ｒ¹⁰＝Ｒ¹¹＝水素原子、Ｒ²¹＝Ｒ²²＝メチル基、ｎ＝１〕を電解液に対して１重量％使用したほかは実施例１と同様に電解液を調製してコイン電池を作製し、電池特性を測定したところ、初期放電容量の相対容量は１．０２であり、５０サイクル後の電池特性を測定したところ、放電容量維持率は９１．８％であった。コイン電池の作製条件および電池特性を表１に示す。
【００４１】
実施例７
アルキン誘導体として２，４−ヘキサジイン−１，６−ジオール ジメタンスルホネート〔一般式（ＩＩＩ）中、Ｙ⁴＝Ｙ⁵＝−ＳＯ₂Ｒ²¹＝−ＳＯ₂Ｒ²²、Ｒ⁸＝Ｒ⁹＝Ｒ¹⁰＝Ｒ¹¹＝水素原子、Ｒ²¹＝Ｒ²²＝メチル基、ｎ＝１〕を電解液に対して１重量％使用したほかは実施例６と同様にコイン電池を作製し、電池特性を測定したところ、初期放電容量の相対容量は１．０３であり、５０サイクル後の電池特性を測定したところ、放電容量維持率は９１．５％であった。また、低温特性も良好であった。コイン電池の作製条件および電池特性を表１に示す。
【００４２】
実施例８
ＰＣ／ＥＣ／ＤＭＣ／ＤＥＣ（容量比）＝１／２／３／４の非水溶媒を調製し、これにＬｉＰＦ₆を１Ｍの濃度になるように溶解して電解液を調製した後、さらにアルキン誘導体としてジ（１，１−ジメチル−２−プロピニル）カーボネート〔一般式（ＩＶ）中、Ｒ¹²＝Ｒ¹⁷＝水素原子、Ｒ¹³＝Ｒ¹⁴＝Ｒ¹⁵＝Ｒ¹⁶＝メチル基、ｎ＝１〕を電解液に対して０．５重量％使用したほかは実施例１と同様に電解液を調製してコイン電池を作製し、電池特性を測定したところ、初期放電容量の相対容量は１．０３であり、５０サイクル後の電池特性を測定したところ、放電容量維持率は９２．６％であった。コイン電池の作製条件および電池特性を表１に示す。
【００４３】
実施例９
正極活物質として、ＬｉＣｏＯ₂に代えてＬｉＭｎ₂Ｏ₄を使用したほかは実施例３と同様に電解液を調製してコイン電池を作製し、電池特性を測定したところ、初期放電容量の相対容量は０．８３であり、５０サイクル後の電池特性を測定したところ、放電容量維持率は９３．１％であった。コイン電池の作製条件および電池特性を表１に示す。
【００４４】
実施例１０
正極活物質として、ＬｉＣｏＯ₂に代えてＬｉＣｏ_0.1Ｎｉ_0.9Ｏ₂を使用し、アルキン誘導体としてジ（１，１−ジメチル−２−プロピニル）カーボネート〔一般式（ＩＶ）中、Ｒ¹²＝Ｒ¹⁷＝水素原子、Ｒ¹³＝Ｒ¹⁴＝Ｒ¹⁵＝Ｒ¹⁶＝メチル基、ｎ＝１〕を電解液に対して０．５重量％使用したほかは実施例３と同様に電解液を調製してコイン電池を作製し、電池特性を測定したところ、初期放電容量の相対容量は１．１９であり、５０サイクル後の電池特性を測定したところ、放電容量維持率は９０．５％であった。コイン電池の作製条件および電池特性を表１に示す。
【００４５】
実施例１１
負極活物質として、人造黒鉛に代えて天然黒鉛を使用したほかは実施例８と同様に電解液を調製してコイン電池を作製し、電池特性を測定したところ、初期放電容量の相対容量は１．０２であり、５０サイクル後の電池特性を測定したところ、放電容量維持率は９３．２％であった。コイン電池の作製条件および電池特性を表１に示す。
【００４６】
比較例１
ＥＣ／ＤＥＣ（容量比）＝１／２の非水溶媒を調製し、これにＬｉＰＦ₆ を１Ｍの濃度になるように溶解した。このときアルキン誘導体は全く添加しなかった。この電解液を使用して実施例１と同様にコイン電池を作製し、電池特性を測定した。この場合の初期放電容量の相対容量を１とする。初期放電容量に対し、５０サイクル後の放電容量維持率は８２．８％であった。コイン電池の作製条件および電池特性を表１に示す。
【００４７】
【表１】

【００４８】
なお、本発明は記載の実施例に限定されず、発明の趣旨から容易に類推可能な様々な組み合わせが可能である。特に、上記実施例の溶媒の組み合わせは限定されるものではない。更には、上記実施例はコイン電池に関するものであるが、本発明は円筒形、角柱形の電池にも適用される。
【００４９】
【発明の効果】
本発明によれば、広い温度範囲でのサイクル特性や電気容量、更には保存特性などの電池特性に優れたリチウム二次電池を提供することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention provides a novel lithium secondary battery electrolyte that can provide a battery having excellent battery characteristics such as battery cycle characteristics, electric capacity, and storage characteristics, and a lithium secondary battery using the same. It relates to batteries.
[0002]
[Prior art]
In recent years, lithium secondary batteries have been widely used as driving power sources for small electronic devices and the like. A lithium secondary battery is mainly composed of a positive electrode, a non-aqueous electrolyte, and a negative electrode. ₂ A lithium secondary battery having a lithium composite oxide such as a positive electrode and a carbon material or lithium metal as a negative electrode is preferably used. As the electrolyte for the lithium secondary battery, carbonates such as ethylene carbonate (EC) and propylene carbonate (PC) are preferably used.
[0003]
[Problems to be solved by the invention]
However, there is a demand for a secondary battery having more excellent battery characteristics such as battery cycle characteristics and electric capacity.
As the positive electrode active material, for example, LiCoO ₂ , LiMn ₂ O _Four , LiNiO ₂ Lithium rechargeable batteries using the above, etc., partially degrade the oxidative decomposition of the solvent in the non-aqueous electrolyte during charging, and the decomposed product inhibits the desired electrochemical reaction of the battery. Arise. This is probably due to the electrochemical oxidation of the solvent at the interface between the positive electrode material and the non-aqueous electrolyte.
In addition, in a lithium secondary battery using a highly crystallized carbon material such as natural graphite or artificial graphite as a negative electrode active material, peeling of the carbon negative electrode material is observed, and the capacity may be irreversible depending on the degree of the phenomenon. . This peeling is caused by the decomposition of the solvent in the electrolytic solution during charging, and is caused by the electrochemical reduction of the solvent at the interface between the carbon negative electrode material and the electrolytic solution. Among them, an electrolytic solution using a PC having a low melting point and a high dielectric constant has a high electrical conductivity even at a low temperature. However, when a graphite negative electrode is used, the PC is decomposed and cannot be used for a lithium secondary battery. There was a problem. Moreover, EC also partially decomposes during repeated charging and discharging, resulting in a decrease in battery performance. For this reason, at present, battery characteristics such as battery cycle characteristics and electric capacity are not always satisfactory.
[0004]
The present invention solves the above-described problems relating to the electrolyte for a lithium secondary battery, is excellent in battery cycle characteristics, and further excellent in battery characteristics such as electric capacity and storage characteristics in a charged state. It is an object of the present invention to provide an electrolytic solution for a lithium secondary battery that can constitute the battery, and a lithium secondary battery using the same.
[0005]
[Means for Solving the Problems]
The present invention relates to an electrolytic solution in which an electrolyte is dissolved in a non-aqueous solvent, in which the following general formulas (I), (II), (III), (IV),
[0006]
[Chemical 9]

[0007]
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[0008]
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[0009]
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[0010]
(Wherein R ¹ , R ^Four , R ^Five , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ^Ten , R ¹¹ , R ¹² And R ¹⁷ Each independently represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, an aryl group, or a hydrogen atom. However, R ^Four , R ^Five , R ⁶ And R ⁷ Are not simultaneously hydrogen atoms. Where R ² , R ^Three , R ¹³ , R ¹⁴ , R ¹⁵ And R ¹⁶ Each independently represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group. R ² And R ^Three , R ^Four And R ^Five , R ⁶ And R ⁷ , R ¹³ And R ¹⁴ , R ¹⁵ And R ¹⁶ May be bonded to each other to form a cycloalkyl group having 3 to 6 carbon atoms. Where Y ¹ Is -COOR ¹⁸ , -COR ¹⁸ Or -SO ₂ R ¹⁸ , Y ² Is -COOR ¹⁹ , -COR ¹⁹ Or -SO ₂ R ¹⁹ , Y ^Three Is -COOR ²⁰ , -COR ²⁰ Or -SO ₂ R ²⁰ , Y ^Four Is -COOR ^{twenty one} , -COR ^{twenty one} Or -SO ₂ R ^{twenty one} , And Y ^Five Is -COOR ^{twenty two} , -COR ^{twenty two} , -SO ₂ R ^{twenty two} R ¹⁸ , R ¹⁹ , R ²⁰ , R ^{twenty one} And R ^{twenty two} Each independently represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group. However, n shows the integer of 1 or 2. ) Is contained in an amount of 0.01 to 20% by weight based on the weight of the electrolytic solution.
[0011]
Further, the present invention provides a lithium secondary battery comprising an electrolytic solution in which an electrolyte is dissolved in a positive electrode, a negative electrode, and a non-aqueous solvent, the following general formulas (I), (II), (III), (IV),
[0012]
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[0013]
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[0014]
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[0015]
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[0016]
(Wherein R ¹ , R ^Four , R ^Five , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ^Ten , R ¹¹ , R ¹² And R ¹⁷ Each independently represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, an aryl group, or a hydrogen atom. However, R ^Four , R ^Five , R ⁶ And R ⁷ Are not simultaneously hydrogen atoms. Where R ² , R ^Three , R ¹³ , R ¹⁴ , R ¹⁵ And R ¹⁶ Each independently represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group. R ² And R ^Three , R ^Four And R ^Five , R ⁶ And R ⁷ , R ¹³ And R ¹⁴ , R ¹⁵ And R ¹⁶ May be bonded to each other to form a cycloalkyl group having 3 to 6 carbon atoms. Where Y ¹ Is -COOR ¹⁸ , -COR ¹⁸ Or -SO ₂ R ¹⁸ , Y ² Is -COOR ¹⁹ , -COR ¹⁹ Or -SO ₂ R ¹⁹ , Y ^Three Is -COOR ²⁰ , -COR ²⁰ Or -SO ₂ R ²⁰ , Y ^Four Is -COOR ^{twenty one} , -COR ^{twenty one} Or -SO ₂ R ^{twenty one} , And Y ^Five Is -COOR ^{twenty two} , -COR ^{twenty two} , -SO ₂ R ^{twenty two} R ¹⁸ , R ¹⁹ , R ²⁰ , R ^{twenty one} And R ^{twenty two} Each independently represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group. However, n shows the integer of 1 or 2. The lithium secondary battery is characterized in that at least one of the alkyne derivatives represented by (II) is contained in an amount of 0.01 to 20% by weight based on the weight of the electrolyte.
[0017]
The alkyne derivative contained in the electrolytic solution is reduced and decomposed on the surface of the carbon negative electrode prior to the organic solvent in the electrolytic solution at the time of charging, and a part of the decomposed product has an activity such as natural graphite or artificial graphite. By forming a passive film on the highly crystallized carbon negative electrode surface, it is estimated that reductive decomposition of the organic solvent in the electrolytic solution is prevented.
Furthermore, a part of the decomposition product is oxidized and decomposed before the organic solvent in the electrolytic solution at a minute overvoltage portion where the potential on the surface of the positive electrode material is excessively high, so that the organic solvent in the electrolytic solution is oxidized and decomposed. It is estimated that this will be prevented.
Thereby, it is thought that it has the effect which suppresses decomposition | disassembly of electrolyte solution, without impairing the normal reaction of a battery.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
In the alkyne derivative represented by the general formula (I), (II), (III), or (IV) contained in the electrolyte solution in which the electrolyte is dissolved in the nonaqueous solvent, R ¹ , R ^Four , R ^Five , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ^Ten , R ¹¹ , R ¹² And R ¹⁷ Are preferably independently an alkyl group having 1 to 12 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. The alkyl group may be a branched alkyl group such as isopropyl group or isobutyl group. Moreover, a C3-C6 cycloalkyl group like a cyclopropyl group and a cyclohexyl group may be sufficient. Moreover, you may contain a C6-C12 aryl group like a phenyl group, a benzyl group, and p-tolyl group. Furthermore, a hydrogen atom may be sufficient. However, R ^Four , R ^Five , R ⁶ And R ⁷ Are not simultaneously hydrogen atoms. Where R ² , R ^Three , R ¹³ , R ¹⁴ , R ¹⁵ And R ¹⁶ Are preferably independently an alkyl group having 1 to 12 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. The alkyl group may be a branched alkyl group such as isopropyl group or isobutyl group. Moreover, a C3-C6 cycloalkyl group like a cyclopropyl group and a cyclohexyl group may be sufficient. Moreover, you may contain a C6-C12 aryl group like a phenyl group, a benzyl group, and p-tolyl group.
[0019]
Further, Y in the alkyne derivative represented by the general formula (I), (II), or (III) ¹ , Y ² , Y ^Three , Y ^Four And Y ^Five R ¹⁸ , R ¹⁹ , R ²⁰ , R ^{twenty one} And R ^{twenty two} Are preferably independently an alkyl group having 1 to 12 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. The alkyl group may be a branched alkyl group such as isopropyl group or isobutyl group. Moreover, a C3-C6 cycloalkyl group like a cyclopropyl group and a cyclohexyl group may be sufficient. Moreover, you may contain a C6-C12 aryl group like a phenyl group, a benzyl group, and p-tolyl group. R ² And R ^Three , R ^Four And R ^Five , R ⁶ And R ⁷ , R ¹³ And R ¹⁴ , R ¹⁵ And R ¹⁶ May be bonded to each other to form a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, or a cyclohexyl group.
However, n shows the integer of 1 or 2.
[0020]
Specific examples of the alkyne derivative represented by the general formula (I) include, for example, Y ¹ = -COOR ¹⁸ In the case of 1,1-dimethyl-2-propynylmethyl carbonate [R ¹ = Hydrogen atom, R ² = R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1], 1,1-diethyl-2-propynylmethyl carbonate [R ¹ = Hydrogen atom, R ² = R ^Three = Ethyl group, R ¹⁸ = Methyl group, n = 1], 1,1-ethylmethyl-2-propynylmethyl carbonate [R ¹ = Hydrogen atom, R ² = Ethyl group, R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1], 1,1-isobutylmethyl-2-propynylmethyl carbonate [R ¹ = Hydrogen atom, R ² = Isobutyl group, R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1], 1,1-dimethyl-2-butynylmethyl carbonate [R ¹ = R ² = R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1], 1-ethynylcyclohexylmethyl carbonate [R ¹ = Hydrogen atom, R ² And R ^Three Is a bond = pentamethylene group, R ¹⁸ = Methyl group, n = 1], 1,1-phenylmethyl-2-propynylmethyl carbonate [R ¹ = Hydrogen atom, R ² = Phenyl group, R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1], 1,1-diphenyl-2-propynylmethyl carbonate [R ¹ = Hydrogen atom, R ² = R ^Three = Phenyl group, R ¹⁸ = Methyl group, n = 1], 1,1-dimethyl-2-propynylethyl carbonate [R ¹ = Hydrogen atom, R ² = R ^Three = Methyl group, R ¹⁸ = Ethyl group, n = 1] and the like. Y ¹ = -COR ¹⁸ In the case of 1,1-dimethyl-2-propynyl acetate [R ¹ = Hydrogen atom, R ² = R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1], 1,1-diethyl-2-propynyl acetate [R ¹ = Hydrogen atom, R ² = R ^Three = Ethyl group, R ¹⁸ = Methyl group, n = 1], 1,1-ethylmethyl-2-propynyl acetate [R ¹ = Hydrogen atom, R ² = Ethyl group, R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1], 1,1-isobutylmethyl-2-propynyl acetate [R ¹ = Hydrogen atom, R ² = Isobutyl group, R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1], 1,1-dimethyl-2-butynyl acetate [R ¹ = R ² = R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1], 1-ethynylcyclohexyl acetate [R ¹ = Hydrogen atom, R ² And R ^Three Is a bond = pentamethylene group, R ¹⁸ = Methyl group, n = 1], 1,1-phenylmethyl-2-propynyl acetate [R ¹ = Hydrogen atom, R ² = Phenyl group, R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1], 1,1-diphenyl-2-propynyl acetate [R ¹ = Hydrogen atom, R ² = R ^Three = Phenyl group, R ¹⁸ = Methyl group, n = 1], 1,1-dimethyl-2-propynyl propionate [R ¹ = Hydrogen atom, R ² = R ^Three = Methyl group, R ¹⁸ = Ethyl group, n = 1] and the like. Y ¹ = -SO ₂ R ¹⁸ In the case of 1,1-dimethyl-2-propynyl methanesulfonate [R ¹ = Hydrogen atom, R ² = R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1], 1,1-diethyl-2-propynyl methanesulfonate [R ¹ = Hydrogen atom, R ² = R ^Three = Ethyl group, R ¹⁸ = Methyl group, n = 1], 1,1-ethylmethyl-2-propynyl methanesulfonate [R ¹ = Hydrogen atom, R ² = Ethyl group, R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1], 1,1-isobutylmethyl-2-propynyl methanesulfonate [R ¹ = Hydrogen atom, R ² = Isobutyl group, R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1], 1,1-dimethyl-2-butynyl methanesulfonate [R ¹ = R ² = R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1], 1-ethynylcyclohexyl methanesulfonate [R ¹ = Hydrogen atom, R ² And R ^Three Is a bond = pentamethylene group, R ¹⁸ = Methyl group, n = 1], 1,1-phenylmethyl-2-propynyl methanesulfonate [R ¹ = Hydrogen atom, R ² = Phenyl group, R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1], 1,1-diphenyl-2-propynyl methanesulfonate [R ¹ = Hydrogen atom, R ² = R ^Three = Phenyl group, R ¹⁸ = Methyl group, n = 1], ethanesulfonic acid 1,1-dimethyl-2-propynyl [R ¹ = Hydrogen atom, R ² = R ^Three = Methyl group, R ¹⁸ = Ethyl group, n = 1] and the like. However, the present invention is not limited to these compounds.
[0021]
Specific examples of the alkyne derivative represented by the general formula (II) include, for example, Y ² = -COOR ¹⁹ And Y ^Three = -COOR ²⁰ In the case of 3-hexyne-2,5-diol dimethyl dicarbonate [R ^Four = R ⁶ = Methyl group, R ^Five = R ⁷ = Hydrogen atom, R ¹⁹ = R ²⁰ = Methyl group, n = 1], 3-hexyne-2,5-diol diethyl dicarbonate [R ^Four = R ⁶ = Methyl group, R ^Five = R ⁷ = Hydrogen atom, R ¹⁹ = R ²⁰ = Ethyl group, n = 1], 2,5-dimethyl-3-hexyne-2,5-diol dimethyl dicarbonate [R ^Four = R ^Five = R ⁶ = R ⁷ = Methyl group, R ¹⁹ = R ²⁰ = Methyl group, n = 1], 2,5-dimethyl-3-hexyne-2,5-diol diethyl dicarbonate [R ^Four = R ^Five = R ⁶ = R ⁷ = Methyl group, R ¹⁹ = R ²⁰ = Ethyl group, n = 1] and the like. Y ² = -COR ¹⁹ And Y ^Three = -COR ²⁰ In the case of 3-hexyne-2,5-diol diacetate [R ^Four = R ⁶ = Methyl group, R ^Five = R ⁷ = Hydrogen atom, R ¹⁹ = R ²⁰ = Methyl group, n = 1], 3-hexyne-2,5-diol dipropionate [R ^Four = R ⁶ = Methyl group, R ^Five = R ⁷ = Hydrogen atom, R ¹⁹ = R ²⁰ = Ethyl group, n = 1], 2,5-dimethyl-3-hexyne-2,5-diol diacetate [R ^Four = R ^Five = R ⁶ = R ⁷ = Methyl group, R ¹⁹ = R ²⁰ = Methyl group, n = 1], 2,5-dimethyl-3-hexyne-2,5-diol dipropionate [R ^Four = R ^Five = R ⁶ = R ⁷ = Methyl group, R ¹⁹ = R ²⁰ = Ethyl group, n = 1] and the like. Y ² = -SO ₂ R ¹⁹ And Y ^Three = -SO ₂ R ²⁰ In the case of 3-hexyne-2,5-diol dimethanesulfonate [R ^Four = R ⁶ = Methyl group, R ^Five = R ⁷ = Hydrogen atom, R ¹⁹ = R ²⁰ = Methyl group, n = 1], 3-hexyne-2,5-diol diethanesulfonate [R ^Four = R ⁶ = Methyl group, R ^Five = R ⁷ = Hydrogen atom, R ¹⁹ = R ²⁰ = Ethyl group, n = 1], 2,5-dimethyl-3-hexyne-2,5-diol dimethanesulfonate [R ^Four = R ^Five = R ⁶ = R ⁷ = Methyl group, R ¹⁹ = R ²⁰ = Methyl group, n = 1], 2,5-dimethyl-3-hexyne-2,5-diol diethanesulfonate [R ^Four = R ^Five = R ⁶ = R ⁷ = Methyl group, R ¹⁹ = R ²⁰ = Ethyl group, n = 1] and the like. However, the present invention is not limited to these compounds.
[0022]
Specific examples of the alkyne derivative represented by the general formula (III) include, for example, Y ^Four = -COOR ^{twenty one} And Y ^Five = -COOR ^{twenty two} 2,4-hexadiyne-1,6-diol dimethyl dicarbonate [R ⁸ = R ⁹ = R ^Ten = R ¹¹ = Hydrogen atom, R ^{twenty one} = R ^{twenty two} = Methyl group, n = 1], 2,4-hexadiyne-1,6-diol diethyl dicarbonate [R ⁸ = R ⁹ = R ^Ten = R ¹¹ = Hydrogen atom, R ^{twenty one} = R ^{twenty two} = Ethyl group, n = 1], 2,7-dimethyl-3,5-octadiyne-2,7-diol dimethyl dicarbonate [R ⁸ = R ⁹ = R ^Ten = R ¹¹ = Methyl group, R ^{twenty one} = R ^{twenty two} = Methyl group, n = 1], 2,7-dimethyl-3,5-octadiyne-2,7-diol diethyldicarbonate [R ⁸ = R ⁹ = R ^Ten = R ¹¹ = Methyl group, R ^{twenty one} = R ^{twenty two} = Ethyl group, n = 1] and the like. Y ^Four = -COR ^{twenty one} And Y ^Five = -COR ^{twenty two} 2,4-hexadiyne-1,6-diol diacetate [R ⁸ = R ⁹ = R ^Ten = R ¹¹ = Hydrogen atom, R ^{twenty one} = R ^{twenty two} = Methyl group, n = 1], 2,4-hexadiyne-1,6-diol dipropionate [R ⁸ = R ⁹ = R ^Ten = R ¹¹ = Hydrogen atom, R ^{twenty one} = R ^{twenty two} = Ethyl group, n = 1], 2,7-dimethyl-3,5-octadiyne-2,7-diol diacetate [R ⁸ = R ⁹ = R ^Ten = R ¹¹ = Methyl group, R ^{twenty one} = R ^{twenty two} = Methyl group, n = 1], 2,7-dimethyl-3,5-octadiyne-2,7-diol dipropionate [R ⁸ = R ⁹ = R ^Ten = R ¹¹ = Methyl group, R ^{twenty one} = R ^{twenty two} = Ethyl group, n = 1] and the like. Y ^Four = -SO ₂ R ^{twenty one} And Y ^Five = -SO ₂ R ^{twenty two} 2,4-hexadiyne-1,6-diol dimethanesulfonate [R ⁸ = R ⁹ = R ^Ten = R ¹¹ = Hydrogen atom, R ^{twenty one} = R ^{twenty two} = Methyl group, n = 1], 2,4-hexadiyne-1,6-diol diethanesulfonate [R ⁸ = R ⁹ = R ^Ten = R ¹¹ = Hydrogen atom, R ^{twenty one} = R ^{twenty two} = Ethyl group, n = 1], 2,7-dimethyl-3,5-octadiyne-2,7-diol dimethanesulfonate [R ⁸ = R ⁹ = R ^Ten = R ¹¹ = Methyl group, R ^{twenty one} = R ^{twenty two} = Methyl group, n = 1], 2,7-dimethyl-3,5-octadiyne-2,7-diol diethanesulfonate [R ⁸ = R ⁹ = R ^Ten = R ¹¹ = Methyl group, R ^{twenty one} = R ^{twenty two} = Ethyl group, n = 1] and the like. However, the present invention is not limited to these compounds.
[0023]
Specific examples of the alkyne derivative represented by the general formula (IV) include, for example, di (1,1-dimethyl-2-propynyl) carbonate [R ¹² = R ¹⁷ = Hydrogen atom, R ¹³ = R ¹⁴ = R ¹⁵ = R ¹⁶ = Methyl group, n = 1], di (1,1-diethyl-2-propynyl) carbonate [R ¹² = R ¹⁷ = Hydrogen atom, R ¹³ = R ¹⁴ = R ¹⁵ = R ¹⁶ = Ethyl group, n = 1], di (1,1-ethylmethyl-2-propynyl) carbonate [R ¹² = R ¹⁷ = Hydrogen atom, R ¹³ = R ¹⁵ = Ethyl group, R ¹⁴ = R ¹⁶ = Methyl group, n = 1], di (1,1-isobutylmethyl-2-propynyl) carbonate [R ¹² = R ¹⁷ = Hydrogen atom, R ¹³ = R ¹⁵ = Isobutyl group, R ¹⁴ = R ¹⁶ = Methyl group, n = 1], di (1,1-dimethyl-2-butynyl) carbonate [R ¹² = R ¹⁷ = R ¹³ = R ¹⁴ = R ¹⁵ = R ¹⁶ = Methyl group, n = 1], di (1-ethynylcyclohexyl) carbonate [R ¹² = R ¹⁷ = Hydrogen atom, R ¹³ And R ¹⁴ Is a bond = pentamethylene group, R ¹⁵ And R ¹⁶ Is a bond = pentamethylene group, n = 1]. However, the present invention is not limited to these compounds.
[0024]
In the alkyne derivative, if the content of the alkyne derivative represented by the general formulas (I), (II), (III), and (IV) is excessively large, the conductivity of the electrolyte changes and the battery performance is changed. If the amount is too small, a sufficient film is not formed, and the expected battery characteristics cannot be obtained. Therefore, 0.01 to 20% by weight, particularly 0.1% with respect to the weight of the electrolytic solution. A range of -10 wt% is preferred.
[0025]
As the non-aqueous solvent used in the present invention, a solvent composed of a high dielectric constant solvent and a low viscosity solvent is preferable.
Preferred examples of the high dielectric constant solvent include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and vinylene carbonate (VC). These high dielectric constant solvents may be used alone or in combination of two or more.
[0026]
Examples of the low viscosity solvent include chain carbonates such as dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), and diethyl carbonate (DEC), tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2- Ethers such as dimethoxyethane, 1,2-diethoxyethane, 1,2-dibutoxyethane, lactones such as γ-butyrolactone, nitriles such as acetonitrile, esters such as methyl propionate, amides such as dimethylformamide Kind. These low viscosity solvents may be used alone or in combination of two or more.
The high dielectric constant solvent and the low viscosity solvent are arbitrarily selected and used in combination. The high dielectric constant solvent and the low viscosity solvent are usually used in a volume ratio (high dielectric constant solvent: low viscosity solvent) of 1: 9 to 4: 1, preferably 1: 4 to 7: 3. The
[0027]
Examples of the electrolyte used in the present invention include LiPF. ₆ , LiBF _Four LiClO _Four , LiN (SO ₂ CF _Three ) ₂ , LiN (SO ₂ C ₂ F _Five ) ₂ , LiC (SO ₂ CF _Three ) _Three , LiPF _Four (CF _Three ) ₂ , LiPF _Three (C ₂ F _Five ) _Three , LiPF _Three (CF _Three ) _Three , LiPF _Three (Iso-C _Three F ₇ ) _Three , LiPF _Five (Iso-C _Three F ₇ ). These electrolytes may be used alone or in combination of two or more. These electrolytes are used by being dissolved in the non-aqueous solvent usually at a concentration of 0.1 to 3M, preferably 0.5 to 1.5M.
[0028]
The electrolytic solution of the present invention is prepared, for example, by mixing the above-mentioned high dielectric constant solvent or low-viscosity solvent, and dissolving the above-mentioned electrolyte in this, and the above general formulas (I), (II), (III), (IV) It can be obtained by dissolving at least one of the alkyne derivatives represented by the formula:
[0029]
The electrolytic solution of the present invention is suitably used as a constituent member of a secondary battery, particularly as a constituent member of a lithium secondary battery. The constituent members other than the electrolytic solution constituting the secondary battery are not particularly limited, and various conventionally used constituent members can be used.
[0030]
For example, a composite metal oxide of at least one metal selected from the group consisting of cobalt, manganese, nickel, chromium, iron and vanadium and lithium is used as the positive electrode active material. As such a composite metal oxide, for example, LiCoO ₂ , LiMn ₂ O _Four , LiNiO ₂ Etc.
[0031]
The positive electrode is composed of a conductive agent such as acetylene black and carbon black, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), a copolymer of styrene and butadiene (SBR), a copolymer of acrylonitrile and butadiene. After kneading with a binder such as a polymer (NBR), carboxymethyl cellulose (CMC) to form a positive electrode mixture, this positive electrode material is rolled into an aluminum or stainless steel foil or lath plate as a current collector, It is produced by heat treatment under vacuum at a temperature of about 50 ° C. to 250 ° C. for about 2 hours.
[0032]
Examples of the negative electrode (negative electrode active material) include lithium metal and lithium alloy, and carbon materials having a graphite-type crystal structure capable of inserting and extracting lithium (pyrolytic carbons, cokes, graphites (artificial graphite, natural graphite, etc.)) , Organic polymer compound combustion body, carbon fiber] and composite tin oxide are used. In particular, the lattice spacing (d) of the lattice plane (002) ₀₀₂ ) Is preferably a carbon material having a graphite type crystal structure of 0.335 to 0.340 nm (nanometer). Powder materials such as carbon materials are ethylene propylene diene terpolymer (EPDM), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), a copolymer of styrene and butadiene (SBR), and a copolymer of acrylonitrile and butadiene. Kneaded with a binder such as a polymer (NBR) or carboxymethylcellulose (CMC) and used as a negative electrode mixture.
[0033]
The structure of the lithium secondary battery is not particularly limited, and has a single-layer or multiple-layer positive electrode, negative electrode, and separator having a separator, a coin-type battery or a polymer battery, and a roll-shaped positive electrode, negative electrode, and roll-shaped separator. Examples include a cylindrical battery and a square battery. A known polyolefin microporous film, woven fabric, non-woven fabric or the like is used as the separator.
[0034]
【Example】
Next, an Example and a comparative example are given and this invention is demonstrated concretely.
Example 1
(Preparation of electrolyte)
A non-aqueous solvent with EC / DEC (volume ratio) = 1/2 was prepared, and LiPF was added thereto. ₆ Was dissolved to a concentration of 1M to prepare an electrolytic solution, and then 1,1-dimethyl-2-propynylmethyl carbonate [in general formula (I), Y ¹ = -COOR ¹⁸ , R ¹ = Hydrogen atom, R ² = R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1] was added to 2 wt% with respect to the electrolytic solution.
[0035]
[Production of lithium secondary battery and measurement of battery characteristics]
LiCoO ₂ 80% by weight of (positive electrode active material), 10% by weight of acetylene black (conductive agent), and 10% by weight of polyvinylidene fluoride (binder) are mixed, and 1-methyl-2-pyrrolidone is added thereto. The slurry was applied to the aluminum foil. Then, this was dried and pressure-molded to prepare a positive electrode. 90% by weight of artificial graphite (negative electrode active material) and 10% by weight of polyvinylidene fluoride (binder) are mixed, and 1-methyl-2-pyrrolidone is added to this to form a slurry on a copper foil. Applied. Then, this was dried and pressure-molded to prepare a negative electrode. And using the separator of a polypropylene microporous film, said electrolyte solution was inject | poured and the coin battery (diameter 20mm, thickness 3.2mm) was produced.
Using this coin battery, it was charged at a constant current and a constant voltage of 0.8 mA at room temperature (20 ° C.) for 5 hours to a final voltage of 4.2 V, and then at a constant current of 0.8 mA and a final voltage of 2 The battery was discharged to 7 V, and this charge / discharge was repeated. Initial discharge capacity is 1M LiPF ₆ + EC / DEC (capacity ratio) = 1/2 was calculated as the relative capacity in comparison with the case where Comparative Example 1 was used (Comparative Example 1), and was 1.03. When the battery characteristics after 50 cycles were measured, the discharge capacity retention rate when the initial discharge capacity was 100% was 92.2%. Also, the low temperature characteristics were good. The production conditions and battery characteristics of the coin battery are shown in Table 1.
[0036]
Example 2
A non-aqueous solvent with EC / DEC (volume ratio) = 1/2 was prepared, and LiPF was added thereto. ₆ Was dissolved to a concentration of 1M to prepare an electrolytic solution, and then 1,1-ethylmethyl-2-propynyl acetate [Y in general formula (I) as an alkyne derivative. ¹ = -COR ¹⁸ , R ¹ = Hydrogen atom, R ² = Ethyl group, R ^Three = Methyl group, R ¹⁸ = Methyl group, n = 1] was added to 2 wt% with respect to the electrolytic solution. Using this electrolytic solution, a coin battery was produced in the same manner as in Example 1, and the battery characteristics were measured. The initial discharge capacity was 1M LiPF. ₆ + EC / DEC (capacity ratio) = 1/2 was calculated as the relative capacity in comparison with the case where Comparative Example 1 was used (Comparative Example 1), and was 1.02. When the battery characteristics after 50 cycles were measured, the discharge capacity retention rate when the initial discharge capacity was 100% was 91.5%. The production conditions and battery characteristics of the coin battery are shown in Table 1.
[0037]
Example 3
PC / EC / DEC (volume ratio) = 1/2/7 non-aqueous solvent is prepared, and LiPF ₆ Was dissolved to a concentration of 1M to prepare an electrolytic solution, and further, 1,1-diethyl-2-propynyl methanesulfonate [in general formula (I), Y ¹ = -SO ₂ R ¹⁸ , R ¹ = Hydrogen atom, R ² = R ^Three = Ethyl group, R ¹⁸ = Methyl group, n = 1] was used in the same manner as in Example 1 except that 2% by weight of the electrolyte was used. The coin battery was prepared and the battery characteristics were measured. The relative capacity was 1.05, and the battery characteristics after 50 cycles were measured. The discharge capacity retention rate was 91.9%. Also, the low temperature characteristics were good. The production conditions and battery characteristics of the coin battery are shown in Table 1.
[0038]
Example 4
2,5-dimethyl-3-hexyne-2,5-diol diethyldicarbonate [in general formula (II), Y ² = Y ^Three = -COOR ¹⁹ = -COOR ²⁰ , R ^Four = R ^Five = R ⁶ = R ⁷ = Methyl group, R ¹⁹ = R ²⁰ = Ethyl group, n = 1] was used in the same manner as in Example 3 except that 1% by weight of the electrolyte was used, and the battery characteristics were measured. The relative capacity of the initial discharge capacity was 1.02. When the battery characteristics after 50 cycles were measured, the discharge capacity retention rate was 91.1%. Also, the low temperature characteristics were good. The production conditions and battery characteristics of the coin battery are shown in Table 1.
[0039]
Example 5
3-hexyne-2,5-diol dimethanesulfonate as an alkyne derivative [in general formula (II), Y ² = Y ^Three = -SO ₂ R ¹⁹ = -SO ₂ R ²⁰ , R ^Four = R ⁶ = Methyl group, R ^Five = R ⁷ = Hydrogen atom, R ¹⁹ = R ²⁰ = Methyl group, n = 1] was used in the same manner as in Example 3 except that 1% by weight of the electrolyte was used, and the battery characteristics were measured. The relative capacity of the initial discharge capacity was 1.03. When the battery characteristics after 50 cycles were measured, the discharge capacity retention rate was 91.6%. Also, the low temperature characteristics were good. The production conditions and battery characteristics of the coin battery are shown in Table 1.
[0040]
Example 6
PC / EC / MEC (volume ratio) = 1/2/7 non-aqueous solvent is prepared, and LiPF ₆ Was dissolved to a concentration of 1M to prepare an electrolytic solution, and 2,4-hexadiyne-1,6-diol dimethyl dicarbonate [Y in general formula (III) was further used as an alkyne derivative. ^Four = Y ^Five = -COOR ^{twenty one} = -COOR ^{twenty two} , R ⁸ = R ⁹ = R ^Ten = R ¹¹ = Hydrogen atom, R ^{twenty one} = R ^{twenty two} = Methyl group, n = 1] was used in an amount of 1% by weight with respect to the electrolytic solution, and an electrolytic solution was prepared in the same manner as in Example 1 to produce a coin battery and measured for battery characteristics. The relative capacity was 1.02, and when the battery characteristics after 50 cycles were measured, the discharge capacity retention rate was 91.8%. The production conditions and battery characteristics of the coin battery are shown in Table 1.
[0041]
Example 7
2,4-hexadiyne-1,6-diol dimethanesulfonate as an alkyne derivative [in general formula (III), Y ^Four = Y ^Five = -SO ₂ R ^{twenty one} = -SO ₂ R ^{twenty two} , R ⁸ = R ⁹ = R ^Ten = R ¹¹ = Hydrogen atom, R ^{twenty one} = R ^{twenty two} = Methyl group, n = 1] was used in the same manner as in Example 6 except that 1% by weight of the electrolyte was used, and the battery characteristics were measured. The relative capacity of the initial discharge capacity was 1.03. When the battery characteristics after 50 cycles were measured, the discharge capacity retention rate was 91.5%. Also, the low temperature characteristics were good. The production conditions and battery characteristics of the coin battery are shown in Table 1.
[0042]
Example 8
PC / EC / DMC / DEC (volume ratio) = 1/2/3/4 non-aqueous solvent is prepared, and LiPF ₆ Was dissolved to a concentration of 1 M to prepare an electrolytic solution, and then di (1,1-dimethyl-2-propynyl) carbonate [in general formula (IV), R ¹² = R ¹⁷ = Hydrogen atom, R ¹³ = R ¹⁴ = R ¹⁵ = R ¹⁶ = Methyl group, n = 1] was used in the same manner as in Example 1 except that 0.5% by weight of the electrolyte was used, and a coin battery was prepared. The relative capacity of the capacity was 1.03, and when the battery characteristics after 50 cycles were measured, the discharge capacity retention rate was 92.6%. The production conditions and battery characteristics of the coin battery are shown in Table 1.
[0043]
Example 9
LiCoO as positive electrode active material ₂ Instead of LiMn ₂ O _Four In the same manner as in Example 3, an electrolyte solution was prepared to produce a coin battery, and the battery characteristics were measured. The relative capacity of the initial discharge capacity was 0.83, and the battery characteristics after 50 cycles were measured. When measured, the discharge capacity retention rate was 93.1%. The production conditions and battery characteristics of the coin battery are shown in Table 1.
[0044]
Example 10
LiCoO as positive electrode active material ₂ Instead of LiCo _0.1 Ni _0.9 O ₂ And di (1,1-dimethyl-2-propynyl) carbonate [in general formula (IV), R ¹² = R ¹⁷ = Hydrogen atom, R ¹³ = R ¹⁴ = R ¹⁵ = R ¹⁶ = Methyl group, n = 1] was used in the same manner as in Example 3 except that 0.5 wt% of the electrolyte was used, and a coin battery was prepared. The relative capacity was 1.19, and the battery characteristics after 50 cycles were measured. The discharge capacity retention rate was 90.5%. The production conditions and battery characteristics of the coin battery are shown in Table 1.
[0045]
Example 11
A coin battery was prepared by preparing an electrolyte solution in the same manner as in Example 8 except that natural graphite was used instead of artificial graphite as the negative electrode active material, and the battery characteristics were measured. The relative capacity of the initial discharge capacity was 1 The battery characteristics after 50 cycles were measured, and the discharge capacity retention rate was 93.2%. The production conditions and battery characteristics of the coin battery are shown in Table 1.
[0046]
Comparative Example 1
A non-aqueous solvent with EC / DEC (volume ratio) = 1/2 was prepared, and LiPF was added thereto. ₆ Was dissolved to a concentration of 1M. At this time, no alkyne derivative was added. Using this electrolytic solution, a coin battery was produced in the same manner as in Example 1, and the battery characteristics were measured. In this case, the relative capacity of the initial discharge capacity is 1. The discharge capacity retention rate after 50 cycles was 82.8% with respect to the initial discharge capacity. The production conditions and battery characteristics of the coin battery are shown in Table 1.
[0047]
[Table 1]

[0048]
In addition, this invention is not limited to the Example described, The various combination which can be easily guessed from the meaning of invention is possible. In particular, the combination of solvents in the above examples is not limited. Furthermore, although the said Example is related with a coin battery, this invention is applied also to a cylindrical and prismatic battery.
[0049]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the lithium secondary battery excellent in battery characteristics, such as cycling characteristics in a wide temperature range, an electrical capacity, and also a storage characteristic can be provided.

Claims (2)

In an electrolytic solution in which an electrolyte is dissolved in a non-aqueous solvent, the following general formula (I), (II), (III), (IV),

Wherein R ¹ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² and R ¹⁷ are each independently an alkyl group having 1 to 12 carbon atoms. Represents a cycloalkyl group having 3 to 6 carbon atoms, an aryl group, or a hydrogen atom, provided that R ⁴ , R ⁵ , R ^6, and R ⁷ are not hydrogen atoms at the same time, wherein R ² , R ³ , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ each independently represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group, and R ² and R ³ , R ⁴ and R ⁵ , R ⁶ and R ⁷ , R ¹³ and R ¹⁴ , R ¹⁵ and R ¹⁶ may be bonded to each other to form a cycloalkyl group having 3 to 6 carbon atoms. Y ¹ is, -COOR ^18, -COR ¹⁸ or -SO ^₂ R ^18, Y ₂ is, -COOR ^19, -COR ¹⁹ or -SO ₂ R ^19, Y ³ is, -COOR ^20, COR ²⁰ or -SO ₂ R ^20, Y ⁴ is, -COOR ^21, -COR ²¹ or -SO ₂ R ^21, and Y ^5, -COOR ^22, -COR ^22, shows a -SO ₂ R ^22, wherein R ¹⁸ , R ¹⁹ , R ²⁰ , R ²¹ and R ²² each independently represent an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group, where n is 1 or 2 An electrolyte solution for a lithium secondary battery, wherein at least one of the alkyne derivatives represented by the formula (1) is contained in an amount of 0.01 to 20% by weight based on the weight of the electrolyte solution. In a lithium secondary battery comprising an electrolytic solution in which an electrolyte is dissolved in a positive electrode, a negative electrode, and a nonaqueous solvent, the following general formulas (I), (II), (III), (IV),

Wherein R ¹ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² and R ¹⁷ are each independently an alkyl group having 1 to 12 carbon atoms. Represents a cycloalkyl group having 3 to 6 carbon atoms, an aryl group, or a hydrogen atom, provided that R ⁴ , R ⁵ , R ^6, and R ⁷ are not hydrogen atoms at the same time, wherein R ² , R ³ , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ each independently represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group, and R ² and R ³ , R ⁴ and R ⁵ , R ⁶ and R ⁷ , R ¹³ and R ¹⁴ , R ¹⁵ and R ¹⁶ may be bonded to each other to form a cycloalkyl group having 3 to 6 carbon atoms. Y ¹ is, -COOR ^18, -COR ¹⁸ or -SO ^₂ R ^18, Y ₂ is, -COOR ^19, -COR ¹⁹ or -SO ₂ R ^19, Y ³ is, -COOR ^20, COR ²⁰ or -SO ₂ R ^20, Y ⁴ is, -COOR ^21, -COR ²¹ or -SO ₂ R ^21, and Y ^5, -COOR ^22, -COR ^22, shows a -SO ₂ R ^22, wherein R ¹⁸ , R ¹⁹ , R ²⁰ , R ²¹ and R ²² each independently represent an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group, where n is 1 or 2 The lithium secondary battery is characterized in that 0.01 to 20% by weight of at least one alkyne derivative represented by formula (1) is contained with respect to the weight of the electrolytic solution.