Facile Construction of 3D Reduced Graphene Oxide Wrapped Ni 3 S 2 Nanoparticles on Ni Foam for High‐Performance Asymmetric Supercapacitor Electrodes

3D reduced graphene oxide (rGO)‐wrapped Ni 3 S 2 nanoparticles on Ni foam with porous structure is successfully synthesized via a facile one‐step solvothermal method. This unique structure and the positive synergistic effect between Ni 3 S 2 nanoparticles and graphene can greatly improve the electrochemical performance of the NF@rGO/Ni 3 S 2 composite. Detailed electrochemical measurements show that the NF@rGO/Ni 3 S 2 composite exhibits excellent supercapacitor performance with a high specific capacitance of 4048 mF cm −2 (816.8 F g −1 ) at a current density of 5 mA cm −2 (0.98 A g −1 ), as well as long cycling ability (93.8% capacitance retention after 6000 cycles at a current density of 25 mA cm −2 ). A novel aqueous asymmetric supercapacitor is designed using the NF@rGO/Ni 3 S 2 composite as positive electrode and nitrogen‐doped graphene as negative electrode. The assembled device displays an energy density of 32.6 W h kg −1 at a power density of 399.8 W kg −1 , and maintains 16.7 W h kg −1 at 8000.2 W kg −1 . This outstanding performance promotes the as‐prepared NF@rGO/Ni 3 S 2 composite to be ideal electrode materials for supercapacitors.