The High Temperature Operation of Lithium Secondary Batteries with Using Ionic Liquids

The charge and discharge of LiFePO4 half-cells using bis(trifluoromethylsulfonyl)amide based onium salts, such as 1-ethyl-3-methylimidazolium, N,N-diethyl-N-methyl-N-(2-methoyethyl)ammonium, N-methyl-N-propylpiperidinium, N-methyl-N-propypyrrolidinium, and N, N,N,N-tetraethylammonium were investigated at over 100 degrees C. The cell containing tetraethylammonium based melt exhibited best cyclability even at over 125 degrees C. The cell performances also depend on a concentration of lithium salt, the kind of separator and cell holder.