Venus flytrap-like hierarchical NiCoMn–O@NiMoO4@C nanosheet arrays as free-standing core-shell electrode material for hybrid supercapacitor with high electrochemical performance

Abstract

In order to improve the sluggish kinetics of the redox reactions occurring at the battery-type electrodes of hybrid supercapacitors, a Venus flytrap-like hierarchical NiCoMn–O@NiMoO4@C nanosheet arrays electrode material are developed based on three aspects of considerations: 1. The developed NiCoMn-based trimetallic (NiCoMn–O) oxides has better electrical conductivity than any of its bimetallic or monometallic counterparts and the self-decorated nanoneedles on its surface can create more electroactive sites for electrolyte to access. 2 NiMoO4 layer is one of the important redox active materials in this composite since its high electrochemical activity in alkaline solution. 3. Carbon protection shell cannot only enhance the rate capability by shorting the electron transport pathway of the composite but also improve its cycling stability via buffering the volume change during the charge/discharge processes. Consequently, the obtained NiCoMn–O@NiMoO4@C electrode can provide a maximum specific capacitance of 2189.5 F/g (at 0.25 A/g) and 81.6% of its initial specific capacitance can be maintained after 1500 cycles GCD tests (at 6 A/g). The prepared NiCoMn–O@NiMoO4@C//AC hybrid supercapacitor exhibits the maximum energy density of 59.9 Wh/kg (at 0.25 A/g) and its specific capacitance can maintain 88.3% of its initial value after 3000 cycles GCD tests (at 6 A/g).