Carbon Wrapped Amorphous Ni–Co Binary Oxide Nano-Sheet for High Performance Pseudocapacitors

Abstract

The development of high energy density supercapacitor demand that the electrode has the characteristic of well conductivity for electron and open framework structure for ion transfer. NiCo2O4 already exhibits superior electric conductivity among the multi-metal oxides. Here, carbon wrapped amorphous Ni-Co oxide nano-sheet is prepared by hydrothermal followed Ar atmosphere annealing process. The conductivity is further improved by carbon coating. And it also has a more open structure which is verified by extended X-ray absorption fine structure analysis. Owing to the advantage structure, the carbon wrapped amorphous Ni-Co oxide shows large capacitance of 1775 F g-1 at 1 A g-1 in three electrode aqueous system, high energy density of 73.5 Wh kg-1 and power density of 806.7 W kg-1 in asymmetric supercapacitors. The open framework feature of the amorphous would promote the wide exploration of amorphous Ni-Co oxide material as the electrode for energy storage devices.