成果報告書詳細
管理番号20110000000504
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 要素技術開発 高出力・高安全性リチウムイオン電池の開発
公開日2012/6/27
報告書年度2010 - 2010
委託先名第一工業製薬株式会社 学校法人関西大学 エレクセル株式会社
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1. 研究開発の内容及び成果等
1-1. 各イオン液体材料の基礎物性解析および電極界面解析評価(学校法人 関西大学)
昨年度取り扱ったLiNi1/3Mn1/3Co1/3O2 正極、これに加えてLi 高電圧作動可能な新規LiNi0.5Mn1.5O4 正極にイオン液体系電解液を用い、充放電挙動解析を単極試験レベルで行うことで良好なマッチングの選定を行った。LiNi0.5Mn1.5O4 正極ではイオン液体のカチオンを選定することで良好なセル性能が得られることを見出した。また、これと並行して、エレクセル株式会社で検討している新規正極材料に関しても同様の単極レベルでの解析を行った。正極材料の導電剤を最適化するとによって、単極試験レベルではカーボネート系を溶媒とした一般的な電解液よりもレート特性、サイクル特性が良好であることがわかった。これらの結果に関してはフルセル構築を進めているエレクセル株式会社にフィードバックした。
英文要約Title: Development of High-performance Battery System for Next-generation Vehicles / Development of Elemental Technology / Development of High-performance Lithium Ion Batteries (FY2007-FY2011) FY2010 Annual Report

The research group at Kansai University has mainly investigated charge/discharge behavior of several cathodes and an anode in in bis(fluorosulfonyl)imide (FSI) based ionic liquids. Summary of annual research is presented below. We employed two active materials, LiNi0.5Mn1.5O4 (NM) and LiNi1/3Mn1/3Co1/3O2 (NMC), for cathodes and investigated their electrochemical behavior in FSI-based ionic liquids. According to 1.0/1.0 C-rate charge/discharge measurements in the potential range of 3.0 - 4.5 V vs. Li/Li+, the NMC cathode in EMIFSI (EMI+ = 1-ethyl-3-methylimidazolium) maintains 94.6% of this initial discharge capacity after 100 cycles, suggesting that FSI-based ionic liquids provides relatively stable operation of the NMC cathode without any additives or electrode surface treatments. Furthermore, the NMC cathode in FSI-based ionic liquids also represents good rate capability of 77% at 5.0 C (46% for conventional electrolyte of LiPF6/EC+DMC). On the other hand, we found that not EMIFSI but an aliphatic cation-based liquid is suitable for the NM cathode because of its higher operating potential (~ 4.9 V vs. Li/Li+) where EMI+ decompose. Cycle performance of a graphite-based anode in EMIFSI was also investigated; this anode keep coulombic efficiency >99% at 1.0/1.0 C charging/discharging. Consequently, we have attained our goals as 100%; we obtained the discharge capacity retention of 94.6% after 100 cycles for the NMC cathode in EMIFSI; we can choice aliphatic cation based liquids for high voltage cathode materials, such as NM; a graphite anode shows >99% coulombic efficiency in FSI-based ionic liquid. The annual results by the research group at Dai-Ichi Kogyo Seiyaku and Elexcel were as follows. Regarding the search for new series of FSI-based ionic liquids, we prepared two liquids; one is AEIFSI (AEM+ = 1-allyl-3-ethylimidazolium), the other is DAIFSI (DAI+ = 1,3-diallylimidazolium). Both show liquidus phase at room temperature, and we found AEIFSI have high ionic conductivity of 14.0 mS/cm2 and low melting point of -46.0 degree C, which are equivalent to EMIFSI. In Elexcel group, according to the results obtained at Kansai University and Dai-Ichi Kogyo Seiyaku, we constructed a practical 1.5 Ah cell with the selection for each component. The power density of the cell was reached to 2,680 W/kg, estimated by the I-V method. We evaluated the low temperature operation (0 degree C) of the same cell and found that the cell shows 80.5% of the discharge capacity obtained at 25 degree C. As the results mentioned above concludes that we accomplish our goal as 100%.

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