Polypyrrole embedded in nickel-cobalt sulfide nanosheets grown on nickel particles passivated silicon nanowire arrays for high-performance supercapacitors

Abstract

Metal sulfide-based composites have been considered as promising electrode materials for energy storage, but the fabrication process of such composites is complicated and requires a multistep hydrothermal treatment. Considering the integration with the silicon-based microelectronics, electrode materials prepared from 3D silicon and metal sulfide are needed. In this work, a hierarchical multi-shelled Ppy-NCS@Ni@SiNWs electrode was successfully developed with a simple, clean and low-cost method, where polypyrrole (Ppy) and nickel–cobalt sulfide (NCS) were co-electrodeposited on nickel particles passivated silicon nanowire arrays (SiNWs). Benefiting from the large surface of SiNWs, high conductivity of nickel passivation layer and the synergy effect between Ppy and NCS including large capacity, hydrophilic surface and high mechanical strength, the as-prepared electrode demonstrated a remarkable specific capacitance (1602 F g-1 at 1 A g−1), an excellent rate capacity (1348 F g-1 at 30 A g−1) and a high cycling stability (91.6 % of initial capacitance after 10,000 cycles). Additionally, a solid asymmetric supercapacitor was fabricated by employing Ppy-NCS@Ni@SiNWs as the positive electrode, which realized a superior energy density of 131.322 Wh kg−1 at an outstanding power density of 1.44 kW kg−1. The findings demonstrate that the hybrid composite of conductive polymer and metal sulfide grown on 3D silicon has enormous potential for energy storage materials.