Electrochemical Energy Storage Device with a Lewis Acidic AlBr 3 −1-Ethyl-3-methylimidazolioum Bromide Room-Temperature Ionic Liquid

Abstract

Now room-temperature ionic liquid (RTIL) is becoming a general term in the fields of science and technology owing to its useful physicochemical properties. A great number of applications with RTIL are proposed to date. Here we report an original electrochemical energy storage device with a Lewis acidic 60.0–40.0 mol% AlBr3−1-ethyl-3-methylimidazolioum bromide ([C2mim]Br) RTIL. The unique electrochemical reactions related to [AlBr4]− anion on the positive electrode have a crucial role in the energy storage device. The charge-discharge ratio for the beaker cell prepared in this investigation was almost 100% at 2.0 ∼ 5.0 mA (150 ∼ 370 mA g−1 for activated carbon fiber cloth) if the cutoff voltage for the charging process was less than 1.70 V. The clear self-discharge behavior was not observed and the cell capacity after 100 cycles was identical to the maximum value.