Cobalt nickel sulfide anchored on graphene for high performance all-solid-state asymmetric supercapacitors

Transition metal sulfide materials exhibit huge potential in high performance supercapacitors due to high theoretical capacitance and activity. Herein, a facile hydrothermal method has been developed to prepare CoNiS/graphene composite. Due to the porous and stable sandwich like structure and effective ion/electron transfer path, the optimized CoNiS-10GO electrode delivers a large specific capacitance of 746.7 C g−1 at 1 A g−1 and with a 69.3 % initial capacitance retention even at 20 A g−1. Moreover, the prepared asymmetric supercapacitor using CoNiS-10GO as positive electrode and porous carbon as negative electrode shows a large energy density of 37.3 Wh kg−1 and good electrochemical stabilization in PVA/KOH sol electrolyte. Therefore, this research provides a simple, convenient approach for preparation of transition metal sulfides with high performance for supercapacitors.