3D Hierarchical NiCo<sub>2</sub>S<sub>4</sub> Nanoparticles/Carbon Nanotube Sponge Cathode for Highly Compressible Asymmetric Supercapacitors
Xiaoming Yang, Xuexia He, Qi Li, Jie Sun, Zhibin Lei, Zong‐Huai Liu
Abstract
By employing a carbon nanotube (CNT) sponge with a 3D porous network as a compressible substrate and NiCo2S4 nanoparticles as active materials, a NiCo2S4/CNT sponge electrode with high compression characteristics and prominent capacitance is fabricated by a solvothermal method. NiCo2S4 nanoparticles with size ranging from 20 to 25 nm are evenly anchored on the network of a CNT sponge, making it show excellent compression performance and large specific capacitance of 1110 F g–1. Meanwhile, a Fe2O3/CNT sponge as an anode with a specific capacitance of 330 F g–1 for a widening voltage window is also fabricated by hydrothermal reaction technology. A NiCo2S4/CNT//Fe2O3/CNT asymmetric supercapacitor with high compression is assembled using a NiCo2S4/CNT sponge and an Fe2O3/CNT sponge as the cathode and anode electrode, respectively, and its potential window can reach up to 1.7 V. The assembled device not only delivers a high specific capacitance of 117 F g–1 at 1 A g–1, but also shows excellent compression and flexibility. Moreover, it exhibits a superior energy density of 41.6 W h kg–1 and excellent long-run cyclic stability that retains about 82% of the initial capacitance after 5000 cycles under about 80% strain. The NiCo2S4/CNT//Fe2O3/CNT asymmetric supercapacitor may offer a feasible approach for assembling compressible energy devices on account of its remarkable compression property, superior specific capacitance, and distinguished Coulombic efficiency.