Studies on electrical double layer capacitor with a low-viscosity ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate as electrolyte

The performance of an electrical double layer capacitor (EDLC) composed of high surface area activated carbon electrodes and a new ionic liquid, 1-ethyl-3-methylimidazolium tetracyanoborate, EMIm]TCB, as the electrolyte has been investigated by impedance spectroscopy, cyclic voltammetry and galvanostatic charge–discharge studies. The high ionic conductivity (~1·3 × 10^???2 S cm^???1 at 20 °C) and low viscosity (~22 cP) of the ionic liquid, EMIm]TCB, make it attractive as electrolyte for its use in EDLCs. The optimum capacitance value of 195·5 F g^???1 of activated carbon has been achieved with stable cyclic performance.