Effect of electrolyte temperature on the pseudo-capacitive behavior of manganese oxide in N-butyl-N-methylpyrrolidinium–dicyanamide ionic liquid

The electrochemical behavior of anodically deposited Mn oxide in N-butyl-N-methylpyrrolidinium–dicyanamide (BMP–DCA) ionic liquid (IL) at various temperatures (30–80 °C) is investigated. Cyclic voltammetry (CV) is used to evaluate the electrochemical performance of the Mn oxide. Surface morphology of the deposited oxide after charging/discharging is examined by scanning electron microscopy (SEM). The experimental data show that the Mn oxide electrode exhibits good pseudo-capacitance performance even at 80 °C. In the ionic liquid studied, the specific capacitance increases with increasing BMP–DCA IL temperature. A specific capacitance of 93 F g−1 in a potential window of 3 V is obtained at 80 °C, which is about 50% higher than that obtained at 30 °C. The experimental results also show that the capacitance-retained ratio of the oxide electrode increases with increasing temperature at a high potential sweep rate. Furthermore, the capacitance decline about 40% after 500 repeated charging/discharging cycles in BMP–DCA IL at 80 °C is observed, which is better than that measured in an aqueous electrolyte.

► Good pseudo-capacitive performance of Mn oxide was found in BMP–DCA IL at 80 °C. ► Specific capacitance of 93 F g−1 is obtained at 80 °C, which is 50% higher than those obtained at 30 °C. ► The Mn oxide has a high energy and power densities in BMP–DCA IL at high temperature.