Facile synthesis of Ni 3 Se 4 /Ni 0.6 Zn 0.4 O/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, Ni 3 Se 4 , Ni 0.6 Zn 0.4 O 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 NiSe 2 to Ni 3 Se 4 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 Ni 3 Se 4 /Ni 0.6 Zn 0.4 O/ZnO (NNZ-500) nanoparticle material displayed a high specific capacitance of 1089.2 F g -1 at 1 A g -1 , and excellent cycle stability of 99.8% capacitance retention after 2000 cycles at 5 A g -1 . 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 -1 at 819.0 W kg -1 , 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.