A Conjugately Configured Supercapacitor with Suppressed Self-Discharge by Coupling Pairs of Presodiated Manganese Oxides

The wider application of conventional electrochemical double-layer supercapacitors is limited by severe self-discharge. Current strategies for tackling self-discharge are mainly focused on each specific component of the device, while a general approach based on configuration design from the device level is largely unknown. Herein, we report a conjugated supercapacitor based on pairs of presodiated manganese oxides with the unique working mechanism of redox pseudocapacitance. Upon aging, the holding time for voltage dropping from 1.0 to 0.4 V for the conjugated device based on Na x δ-MnO2 vs Na1–x δ-MnO2 is four times longer than that of an activated carbon (AC) vs AC device. The successful suppression of self-discharge based on designing device configuration is expected to be universally viable for other capacitive materials.