3D Hierarchical NiCo2S4 Nanoparticles/Carbon Nanotube Sponge Cathode for Highly Compressible Asymmetric Supercapacitors

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.

Automated summary

A NiCo2S4/CNT sponge electrode with excellent compression performance and large specific capacitance, as well as a Fe2O3/CNT sponge anode with a wide voltage window, have been successfully fabricated. An assembled NiCo2S4/CNT//Fe2O3/CNT asymmetric supercapacitor shows high specific capacitance, excellent compression and flexibility, superior energy density, and good long-term cyclic stability.