Abstract:

Rational design of electrode material structure is a key factor to improve high capacity，energy density，power density and long lifetime of supercapacitors.The ZnCo-based alkaline carbonate nano⁃arrays with high loading were grown in situ on nickel foam mesh by a similar two⁃step hydrothermal method，and the effects of the feeding ratio of metal ions on the microscopic morphology，the crystalline shape of the phases，and the electrochemical performance of the electrode materials were investigated.The test results showed that when n（Zn）∶n（Co）=1∶4，the resulting ZnCo-based alkaline carbonate electrode materials exhibited an upright⁃grown nanosheet array structure，and the nanosheet structure could provide a large specific surface area，while the large spacing between neighboring nanosheets ensured open electrolyte ion mass transfer channels，which enabled excellent charge storage capacity and good cycling stability.At a current density of 10 mA/cm²，the sample area specific capacitance was 3.08 C/cm² and it was stably tested for 15 000 cycles at high current.Moreover，the as⁃assembled supercapacitor with Zn_0.25Co-CH electrode and activated carbon（AC） negative electrode could be operated at a large voltage window of 0~1.8 V，and delivered an energy density of 0.69 mW·h/cm² at the power density of 9 mW/cm².Moreover，the device exhibited an outstanding cycle stability，while the capacity retention after 10 000 cycles was 92.1%.

Key words: ZnCo-based carbonate hydroxide, high mass loading, supercapacitor, cyclic stability