成果報告書詳細
管理番号20150000000239
タイトル*平成26年度中間年報 革新型蓄電池先端科学基礎研究事業 革新型蓄電池先端科学基礎研究開発 (11)
公開日2015/5/26
報告書年度2014 - 2014
委託先名国立大学法人横浜国立大学
プロジェクト番号P09012
部署名スマートコミュニティ部
和文要約
英文要約We are attempting to develop a novel lithium-air secondary battery by using solvate ionic liquid electrolytes. Owing to their chemical and physical properties, ionic liquids have attracted much attention in many applications. We can exploit these advantages in the ionic liquids for designing electrolytes applicable to lithium-air battery with high energy density. Thus developed lithium solvate ionic liquids, consisting of Li[N(SO2CF3)2] and glyme (G3 or G4), are inherently non-flammable, less-volatile, highly lithium-conductive, and highly stable against oxidative reaction. Therefore, they are a promising electrolyte of the lithium-air batteries operated in open-air conditions. Moreover, a variety of the design routes enables us to introduce more hydrophobic property into the solvate ionic liquids. In this project, we also attempt to fabricate lithium-air battery systems composed of not only lithium metal but also graphite as the negative electrode. The final goals in this project ar
e (i) to evaluate the possibility of the battery operation with humidified oxygen or real air using the solvate ionic liquid electrolytes, and (ii) to realize the lithium-air battery that allows the energy density of 500 Wh/kg over 50 cycles of reversible charge-discharge.
In this year, we could find out important knowledge relating to Li-air batteries based on the solvate ionic liquids, as described below. Owing to their both high thermal stability, high oxidative stability, and low solubility of the oxygen-reduction intermediate (LiO2), the solvate ionic liquids are superior to conventional organic electrolyte solutions. More than 5 cycles of stable charge/discharge phenomenon was made possible by using a hydrophobic solvate ionic liquid under humidified oxygen atmosphere. In terms of both oxygen permeability and moisture blocking ability, polytetrafluoroethylene (PTFE) was found to be the best film for a selective membrane of the air electrode. To reduce charging overpotential of air electrode, a new mediator ionic liquid based on iodine redox couple was developed and introduced into the solvate ionic liquid. The redox couple is stable to oxygen anion radical and the charging overpotential was greatly reduced.
We will focus on the reduction of the overpotential of air electrode by using the mediator. And we will also optimize the performance of the full cell [lithium or graphite | solvate ionic liquid | air] next year.
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