Facile synthesis of Ni3Se4/Ni0.6Zn0.4O/ZnO nanoparticle as high-performance electrode materials for electrochemical energy storage device.

To enhance the performance of transition metal chalcogenide composite electrode material, a key point is a composite design and preparation based on the synergistic effect between the oxide and selenide materials. With a facile "one step template-annealing" step, Ni3Se4, Ni0.6Zn0.4O and ZnO are simultaneously synthesized, by 500°C annealing. With the increase of annealing temperature from 350°C to 600°C, nickel selenides change from NiSe2 to Ni3Se4 to NiSe. The charge storage capacity increases first and then decreases with the increase of annealing temperature, and the 500°C annealing obtained three compound composite Ni3Se4/Ni0.6Zn0.4O/ZnO (NNZ-500) nanoparticle material displayed a high specific capacitance of 1089.2 F/g at 1 A/g, and excellent cycle stability of 99.8% capacitance retention after 2000 cycles at 5 A/g. Moreover, an asymmetric supercapacitor was assembled with NNZ-500 as the positive electrode material and activated carbon as the negative electrode material. This kind of asymmetric supercapacitor demonstrated a high energy density of 53.4 Wh/kg at 819.0 W/kg, and cycle stability with 98.6% capacitance retention after 2000 cycles. This material preparation approach provides great potential for the future development of high performance transition metal composite electrode materials in energy storage applications.