The fabrication of nickel-based foam/nanotube current collector to support CoNi-based nanosheets for supercapacitors.

The CoNi-based hydroxide nanosheets (CoNiNSs) are promising active materials for supercapacitors. At the same time, the fabrication of freestanding electrodes is essential to achieve high electrochemical performance without introducing inactive components. To further improve the utilization of electrochemically CoNiNSs, in this study, a nickel-based foam/tube current collector (NF@NT) is rationally fabricated to support CoNiNSs (NF@NT/CoNiNSs). As expected, the freestanding NF@NT/CoNiNSs-2 electrode with optimum CoNiNSs content exhibits favorable electrochemical performance: (i) in the three-electrode system, the specific capacitance is 4.2 F cm−2 at 10 mA cm−2 and 2.38 F cm−2 at 50 mA cm−2, as well as capacitance retention of 97.1 % after 20,000 cycles at 20 mV s−1; (ii) matched with activated carbon (AC), the capacitance of corresponding NF@NT/CoNiNSs-2//AC device maintains 90.74 % after 27,500 cycles at 50 mA cm−2, which also delivers an energy density of 80.8 Wh kg−1 at a comparable power density of 5997.52 W kg−1. • The freestanding NF@NT/CoNiNSs electrode for supercapacitors is fabricated via direct growth of CoNiNSs on NF@NT. • The NF@NT/CoNiNSs electrode endows large contact area with electrolyte, short ion diffusion transport, and fast electron pathway. • The NF@NT/CoNiNSs//AC maintains 90.74 % capacitance after 27,500 cycles at 50 mA cm−2. • The NF@NT/CoNiNSs//AC delivers an energy density of 80.8 Wh kg−1 at a comparable power density of 5997.52 W kg−1. [ABSTRACT FROM AUTHOR]