Mitigating self-discharge of activated carbon-based supercapacitors with hybrid liquid crystal as an electrolyte additive

The application of supercapacitors has been restricted partially due to the high self-discharge rate and large leakage current. In this paper, a nematic hybrid liquid crystal, E7, is adopted as an additive to the electrolyte, and the self-discharge of activated carbon-based supercapacitors is evaluated by tuning various parameters such as initial voltage, current density, temperature and thickness of electrodes. Our results show that the supercapacitors exhibit an obviously lower self-discharge rate due to the contribution of E7, evidenced by the 24 h open circuit potential (OCP) drop from 3 V to 1.4 V with E7, compared to the 24 h OCP drop to 1.1 V in the situation without E7. The leakage current is also reduced from 10 to 2.2 µA with the existence of E7.