Dopamine constructing composite of Ni(HCO3)2-polydopamine-reduced graphene oxide for high performance electrode in hybrid supercapacitors

High performances, cost-effectiveness, and facile preparation of electrode materials are of utmost importance for supercapacitors in practical applications. Herein, Ni(HCO3)2 nanoparticles (NPs) of low cost and environmental friendliness were embedded into polydopamine-reduced graphene oxide (PDA-RGO) networks via cost-effective hydrothermal route. It is shown the conducting PDA can uniformly distributes and robustly immobilizes Ni(HCO3)2 NPs in the nanocomposite while the ionic channels are improved for electrolyte access. Consequently, the as-prepared Ni(HCO3)2-PDA-RGO composite offers the high Faradaic capacity of 870 C g−1 at 0.5 A g−1 and moderate rate capability. Furthermore, the assembled Ni(HCO3)2-PDA-RGO//activated carbon hybrid supercapacitor (HSC) delivers a specific capacity of 192 C g−1 at 0.5 A g−1 within operation voltage window of 1.7 V. The maximum energy density of the HSC reaches to 45.3 Wh kg−1 at a power density of 425 W kg−1, and the initial specific capacity maintains 90.5% after 3000 successive charge-discharge cycles. The high energy density and good cycleability certify the potential of the ternary Ni(HCO3)2-PDA-RGO composite in efficient and long lifetime energy storage systems.