Synthesis of NiGa₂S₄-rGO on nickel foam as advanced electrode for flexible solid-state supercapacitor with superior...

Pseudocapacitive electrode materials employed in supercapacitors may bring in high energy density (ED) and specific capacitance (C_sc), which are critical for their practical applications. Accordingly, logical design of advanced electrode materials is highly demanded to progress high-performance supercapacitors. Here, for the first time, we suggest a straightforward route for the synthesis of NiGa₂S₄-rGO as an advanced cathode material supported on nickel foam (NF) for employed in flexible solid-state asymmetric supercapacitors (FSASCs). Due to an abundant ratio of active sites and large surface area of the NiGa₂S₄-rGO advanced material, the as-prepared NiGa₂S₄-rGO/NF electrode illustrates considerable electrochemical properties including remarkable specific capacitance (C_sc) of 2124.34 F g^-1 with excellent rate capability of 73%, and exceptional durability, which are better than NiGa₂S₄/NF and previously reported transition metal sulfides (TMSs). Furthermore, for the first time a pseudocapacitive advanced anode material of FeSe₂-rGO have been successfully fabricated on a nickel foam (NF) substrate by a facile strategy. Element Selenium as the favorable element was offered into the Fe for enhancement and adjustment of the anode material electrochemical performance. The FeSe₂-rGO/NF advanced anode electrode presents satisfactory electrochemical properties containing an exceptional specific capacitance (C_sc) of 432.40 F g^-1, significant rate performance of 57.84% and superior durability, which are better than FeSe₂/NF electrode and previously studied Fe-based anode material. Considering the remarkable electrochemical performance of the as-prepared pseudocapacitive advanced electrode materials, a FSASC based on the NiGa₂S₄-rGO/NF as the cathode electrode and FeSe₂-rGO/NF as the anode electrode was assembled. The FSASC device delivers superior C_sc of 341.20 F g^-1, outstanding energy density (ED) of 121.31 W h kg^-1, remarkable cycle stability (only 7.30% damage after 5000 charge/discharge (CD) cycles).