In‐Situ Colloidal Synthetic Route to Monodispersed NiCo2S4 Nanoparticles over Nickel Foam for High‐Performance Supercapacitive Charge Storage

Abstract One‐step colloidal synthetic route was adopted to in‐situ grow monodispersed NiCo 2 S 4 nanoparticles (NPs) on nickel foam (NF) from metallic salts with benzyl disulfide in the media of oleylamine and octadecene. Owing to the favorable dispersion and considerable redox activity of NiCo 2 S 4 along with tight and binder‐free connection with NF, the obtained battery‐type supercapacitor delivered a specific capacitance of 1790.8 F g −1 at 1 A g −1 via a three‐electrode system. Simultaneously, it just degraded 40 % at 20 A g −1 and maintained 86.8 % of initial specific capacitance (C 0 ) after 2000 cyclic trials at 10 A g −1 . When the NiCo 2 S 4 NPs were assembled with active carbon (AC) forming an asymmetric capacitor device of NiCo 2 S 4 NPs//AC, it delivered an energy density (E) of 48.7 W h kg −1 at a power density (P) of 161.1 W kg −1 , and kept 21.9 W h kg −1 at a high P of 8.05 kW kg −1 . Meanwhile, the capacitor manifested preeminent cycling life (C=94.5 % C 0 after 5000 cyclic trials) at 5 A g −1 . The in‐situ grown NiCo 2 S 4 NPs on NF without any binder exhibited high performance in energy storage, providing a feasible way to improve the electrochemical performance of the electrode materials.