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

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.