Morphology and composition control of manganese oxide by the pulse reverse electrodeposition technique for high performance supercapacitors

Abstract

Manganese oxide (MnOx) nanostructures were synthesized by the pulse reverse electrodeposition technique for electrode materials of supercapacitors. The morphology and composition of MnOx were controlled by the pattern of applying potential. In the case where constant potential (CP) was applied, a bulk film of aggregated MnO₂ particles was obtained. However, Mn₂O₃ nanostructure was obtained by pulse potential (PP) or pulse reverse potential (PRP) methods (1/0 V or 1/−1 V). Furthermore, fine nanorod morphology with high electrical conductivity was produced by the pulse reverse potential method which resulted in excellent capacitive performance. The specific capacitance of the Mn₂O₃ nanorod structure produced by the PRP method was 448 F g⁻¹ at 10 mV s⁻¹. From charge–discharge testing, specific capacitance values of 306 F g⁻¹ and 211 F g⁻¹ were obtained at current densities of 10 A g⁻¹ and 100 A g⁻¹, respectively, indicating high rate capability. The electrode provided exhibited excellent electrochemical stability with a retention life of 99% after 20 000 cycles.