Three-dimensional microsphere-like cobalt-glycerolate strutted nickel hydroxidenitrate nanoflakes grown by hydrothermal method for asymmetric hybrid supercapacitors

Abstract

The core-shell structure is always a greatly effective structure in asymmetric hybrid supercapacitor, duo to a high specific surface area and porosity that can accommodate partial expansion during the redox reaction. Herein, a cobalt-glycerolate@nickel hydroxidenitrate microsphere (CoG@Ni3(NO3)2·(OH)4) with core-shell structure is prepared by a simple two-step hydrothermal method. The as-produced CoG@Ni3(NO3)2·(OH)4 possesses extremely high specific capacity (265.9 mA h g−1 at 1 A g−1) and an excellent rate capability (with 75.5% of initial capacity at 10 A g−1). In addition, as an cathode material, flower-sphere-like Bi-Bi2Se3 materials is selected to match a new CoG@Ni3(NO3)2·(OH)4//Bi-Bi2Se3 asymmetric supercapacitor. It exhibits a specific capacity (125.1 mA h g−1 at 1 A g−1) and an impressive rate property (with 77.6% of initial capacity at 10 A g−1). Satisfactorily, the asymmetric supercapacitor device, which cleverly assembles by the above two electrode materials, achieves impressive specific energy of 54 Wh kg−1 at 760 W kg−1, and a capacitance retention rate of 80% after 4000 cycles. The excellent performance of the asymmetric supercapacitor proves that the materials possess great potential in the energy storage field.