Multi-layered Heterogeneous Interfaces Created in Co0.85Se@Ni3S4/NF to Enhance Supercapacitor Performances by Multi-step Alternating Electrodeposition

Abstract

Heterogeneous interface construction is of far-reaching significance to optimize the electrochemical performance of electrodes. Herein, a multi-step alternating electrochemical deposition (MAED) method is proposed to alternately deposit Co0.85Se and Ni3S4 nanosheets on nickel foam (NF), forming a special alternant layer by layer structure with multi-layered heterogeneous interfaces. The creation of the multi-layered heterogeneous interfaces provides a large interfacial area for redox reactions with optimum interstitials facilitating the ions diffusion, and thus greatly improve the electrochemical energy storage efficiency. With the increase of the layer number, the material exhibits better and better energy storage performance, and the 8L-Co0.85Se@Ni3S4/NF exhibits the highest specific capacitances of 2508 F g-1 and 1558 F g-1 at a scan rate of 2 mV s-1 and a current density of 1 A g-1, respectively. A 8L-Co0.85Se@Ni3S4/NF//polypyrrole(PPy)/NF asymmetric supercapacitor provides a maximum operation potential window of 1.55 V, and energy densities of 76.98 and 35.74 Wh kg-1 when the power densities are 775.0 and 15500 W kg-1, respectively, superior to most of the related materials reported. Through MAED, the deposited phase and the layer number can be accurately controlled, thus providing an efficient strategy for interface construction so as to increase the electrochemical activity of the energy storage materials.