A Novel Strategy of Multi‐element Nanocomposite Synthesis for High Performance ZnO‐CoSe 2 Supercapacitor Material Development

Main observation and conclusion Developing multi‐element composites is a promising way for high performance supercapacitor material development, and simplifying the synthesis steps is critical for reducing the preparation costs and successful promotion of the materials. A novel one‐step selective reaction strategy is developed, and successfully used to prepare four‐element ZnO‐CoSe 2 (ZOCS) nano‐spherical composites, to be used as supercapacitor materials. Started form nano‐spherical glycerate templates, under the optimal synthesis condition, the obtained ZOCS‐0.125 electrode material exhibits a specific capacitance of 450.7 F/g at 1 A/g and a good rate performance by keeping 76.8% capacitance at 20 A/g. Moreover, the ZOCS‐0.125 electrode exhibits excellent cycle stability of 114.9% capacitance retention after 5000 cycles at 10 A/g. An asymmetric supercapacitor assembled by ZOCS‐0.125 and activated carbon electrodes delivers an energy density of 22.35 Wh/kg at 825 W/kg, and a cycle stability of 105.6% capacitance retention after 5000 cycles. This work not only shows the good potential of the facilely prepared ZnO‐CoSe 2 composite electrode material, but also demonstrates a new strategy for low cost and high performance multielement composite material development, that can be used in a wide range of applications.