Improved low-temperature performance of novel asymmetric supercapacitor with capacitor/battery-capacitor construction

A concept for designing capacitor/battery-capacitor asymmetric supercapacitor is proposed to improve low-temperature capacitance, which consists of a capacitor-type electrode (C) and a capacitor/battery-type composite electrode (NiO/C). This construction overcomes the capacitor-battery asymmetric supercapacitor's shortcoming of losing capacitance characteristics. By adjusting the NiO/C mass ratio to 1/2, the new NiO/C–C asymmetric supercapacitor maintains excellent capacitance feature (rectangular CV curves and symmetrical charge/discharge profiles) as well as enlarging the work potential to 1.5 V, showing improved low-temperature capacitance in comparison with C-C and NiO-C constructions. It is believed to come from the decreased total inner resistance and charge-transfer resistance due to the substitution of NiO electrode with NiO/C composite electrode in the asymmetric supercapacitor. Copyright © 2016 John Wiley & Sons, Ltd.