Co(OH)2 particles decorated Ni3(NO3)1.6(CO3)0.2(OH)4 flower-like composite electrode for high-performance hybrid supercapacitors

Abstract

The favorable spatial structure and electrical conductivity are beneficial to fast ion diffusion and charge transport for improved electrochemical performance in hybrid supercapacitors systems. Herein, the Ni3(NO3)1.6(CO3)0.2(OH)4/Co(OH)2 (NNH/Co(OH)2) composite with three-dimensional flower-like structure was successfully synthesized by a simple solvothermal method. Then, the structure, morphology and composition of the as-prepared composites were investigated by XRD, FTIR, XPS, SEM, HRTEM etc. The result of three-electrode testing revealed that the specific capacity of the NNH/Co(OH)2 electrode (∼967.5 C g−1 at 1 A g−1) was approximately 22.16% higher than that of the NNH electrode (∼792.0 C g−1 at 1 A g−1). Meanwhile, the composites revealed an excellent rate capability (86% capacity retention at 10 A g−1) and good cycling stability. This excellent performance can be attributed to the introduced Co(OH)2 particles provide a better charge transport ability and increase electrochemical active site. Moreover, the hybrid supercapacitor assembled with NNH/Co(OH)2 and AC electrodes exhibited a good energy density as well as cycling performance.