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 ([email protected]) is rationally fabricated to support CoNiNSs ([email protected]/CoNiNSs). As expected, the freestanding [email protected]/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 20000 cycles at 20 mV s−1; (ii) matched with activated carbon (AC), the capacitance of corresponding [email protected]/CoNiNSs-2//AC device maintains 90.74% after 27500 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.