Capacitive Manganese–Cobalt Oxide Thin Films by Radio-Frequency Sputtering

Abstract

Manganese–cobalt oxide thin films are sputtered on graphite foils by radio-frequency sputtering with different volume flow rates of oxygen, sputtering pressure, and power. Next, the manganese–cobalt oxide thin films are annealed at various temperatures. A maximum specific capacitance of 256 F/g is obtained under the optimum conditions (volume flow rate of , sputtering , sputtering , and annealing ) at the 2000th cycle of potential cycling, and these demonstrate its long-term operational stability and good specific capacitance at a higher sweep rate of 100 mV/s. Furthermore, the specific capacitance of the manganese–cobalt oxide electrode with or without annealing gradually increases with an increasing number of the charge–discharge cycle, except for the unannealed electrode after 1000 cycles of potential cycling.