Hierarchical nanosheet-based Ni3S2 microspheres grown on Ni foam for highperformance all-solid-state asymmetric supercapacitors

摘要

The hierarchical nanosheet-based Ni3S2 microspheres directly grew on Ni foam using a two-step hydrothermal method. The microsphere with a diameter of similar to 1 microns and a rough surface was well connected to each other without any binders to provide a larger specific surface area, shorter ion/electron diffusion paths, richer electroactive sites as a supercapacitor electrode. As a threeelectrode supercapacitor, it delivers a high specific capacity of 981.8 F g(-1) at 2 A g(-1), an excellent rate capability of 436.4 F g(-1) at 12 A g(-1), and a good cycling stability of 950.9 F g(-1) with 96.9% retention after 1000 cycles at 2 A g(-1). Furthermore, an asymmetric supercapacitor based on Ni3S2-microsphere as a positive electrode and active carbon as a negative electrode shows a high energy density of 29.4 Wh kg(-1) at 324.5Wkg(-1) and a high power density of 3197.6Wkg(-1) at 15.1 Wh kg(-1). This work demonstrates that nanosheet-based Ni3S2 microspheres coated Ni foam can be an effective electrode for a real supercapacitor.