成果報告書詳細
管理番号20110000000501
タイトル*平成22年度中間年報 次世代自動車用高性能蓄電システム技術開発 次世代技術開発 含フッ素溶媒による高電圧駆動電解液の研究開発
公開日2012/6/27
報告書年度2010 - 2010
委託先名ダイキン工業株式会社 学校法人関西大学
プロジェクト番号P07001
部署名スマートコミュニティ部
和文要約和文要約等以下本編抜粋:
[記載項団
1.研究開発の内容及び成果等
本年度においては、平成 21年度に見出した高電圧動作nj能な基本フッ素電解液を特定の正)U 金属以外の負極材料で 50飾h/kg を達成する可能性がある正極材料)に適用して、高電圧駆動可能で良好な電池特性を発現する電解液組成を見出すことを目標としていた。以ドに本年度の研究開発内容およびその成果を述ベる。
英文要約Title: Development of High-performance Battery System for Next-generation Vehicles / Development for Next-generation / Development of Fluorine-containing Electrolyte for High Voltage (FY2009-FY2011) FY2010 Annual Report
Abstract
To increase energy density of lithium ion battery, it is needed to increase capacity of cathode. To increase capacity of cathode, it is needed to increase charge voltage. Higher charge voltage would draw more capacity from cathode. To increase charge voltage, it is needed to increase voltage endurance of electrolyte. In this project, Kansai University and Daikin Industries will try to develop electrolyte which can be used high voltage region. Summary of annual research is presented below.
This year, we were examined half cell and full cell properties of the electrolyte, which we found last year, to see high-voltage performance of the electrolyte in Li ion battery. Our target in this year was to find electrolyte with property described below.
1: An electrolyte which kept above 90% capacity (compared to the capacity after 5 cycles) after 50 cycles at above 4.5V operation in half cell cycle test.
2: An electrolyte which have internal resistance below 50 ohm in a full cell.
We have evalluated the fluorinated electrolyte in a half cell using LCO and NCA as cathodes. In case of the LCO-based half cell, 91.6% capacity retention and 99.7% coulombic efficiency were observed. On the other hand, 64.3% capacity retention and 98.4% coulombic efficiency were observed at the cell using the conventional electrolyte (EC+DMC). And in case of the NCA-based half cell, 96.2% capacity retention and 99.8% coulombic efficiency were observed at the cell. In both cases, the fluorinated electrolyte has improved high-voltage performance compared to the conventional electrolyte. And we have achieved our target1 in both cases.
This improvement in the cycle performance was confirmed by an electrochemical impedance measurement. We found that the FEC/D2 electrolyte provides a favorable solid electrolyte interface (SEI) at the LiCoO2 cathode, leading to reversible charge-discharge behavior of the cathode. Similar effect of FEC/D2 was also observed at a NMC cathode in high-voltage operation up to 4.7V.
And we have tested 4.5V full cell cycle test by using NCM and NCA as cathodes and graphite as an anode. Internal resistance of the cell using fluorinated electrolyte showed 16ohm, thus we have achieved our target2 and there were no difference of internal resistance compared to conventional electrolyte.
And there observed slight capacity decrease after 60th cycle even at 60 celsius in case using the fluorinated electrolyte. On the other hand, there observed 78% capacity retention was observed after 60th cycle at the same temperature in case using the conventional electrolyte. Thus we have showed that fluorinated electrolytes have possibility to enable high-voltage lithium ion batteries.
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