Two-dimensional cobalt–manganese binary metal oxide porous nanosheets for high-performance supercapacitors

Abstract

Two-dimensional cobalt–manganese binary metal oxides (Co_1.5Mn_1.5O₄) porous nanosheets have been successfully synthetized via a simple liquid phase precipitation method. This thin nanosheet structure can shorten the electrolyte ion diffusion distance. Meanwhile, the abundant mesoporous provides more electrochemical active sites, facilitates ion diffusion, and reduces the volume expansion in the charge/discharge cycling processes. Furthermore, there is a synergistic effect on the electrochemical reaction of Co_1.5Mn_1.5O₄. Owe to the high electrical conductivity, cobalt can decrease the impedance and expedite charge transfer. In return, manganese contributes more capacitance in the binary metal oxides. As a result, the as-prepared Co_1.5Mn_1.5O₄ porous nanosheets exhibit outstanding electrochemical performances, such as a specific capacitance of as high as 472.5 F g⁻¹ at 0.5 A g⁻¹, excellent rate capability of 338.5 F g⁻¹ at 10 A g⁻¹ which is equivalent to about 71.6 % of the capacitance at 0.5 A g⁻¹, and long-term cyclability of almost 100 % capacity retention after 1000 cycles.