Mechanism investigation and suppression of self-discharge in active electrolyte enhanced supercapacitors

The self-discharge (SDC) process of active electrolyte enhanced supercapacitors (AEESCs) was investigated systematically. The AEESC with hydroquinone as an active electrolyte showed higher specific capacitance but much faster SDC compared with electronic double layer supercapacitors. The electrode process of the above AEESC was studied, and the mechanism of the SDC process was investigated quantitatively. The migration of the active electrolyte between two electrodes of the device was found to be the primary reason for the fast SDC. Two strategies were designed to suppress the migration of the active electrolyte. Following these strategies, two new AEESCs were fabricated, with a Nafion (R) membrane as the separator and CuSO4 as the active electrolyte. The two AEESCs showed both high specific capacitances and longer SDC times, demonstrating that the problem of poor energy retention of AEESCs was successfully solved.