Patent ID: 8124264

Claim:
An ionic liquid satisfying the following conditions: (a) the ionic liquid comprises 1-ethyl-3-methyl imidazolium bis-trifluoromethylsulfonylimide (EMI-TSFI) and 1-ethyl-3-methyl imidazolium bis(perfluoroethylsulfonyl)imide (EMI-BETI) and satisfies the condition: (EMI-BETI)/{(EMI-TFSI)+(EMI-BETI)}≧10 mol %, or comprises EMI-TFSI and 1-ethyl-3-methyl imidazolium tetrafluoroborate (EMI-BF 4 ) and satisfies the condition: (EMI-BF 4 )/{(EMI-TFSI)+(EMI-BF 4 )}≧40 mol %; and (b) the ionic liquid has a maximum exothermic heat-flow peak height no greater than 2 W/g as measured by DSC, where a measurement temperature range is from an ordinary temperature to 500° C., and a rate of a temperature rise: 2° C./minute.