Carbonized wood-supported hollow NiCo2S4 eccentric spheres for high-performance hybrid supercapacitors

Hollow structures of electroactive hybrid materials have emerged as fascinating electrode materials for energy storage applications. Herein, we prepared an elegantly designed composite with carbonized wood (CW)-supported hollow NiCo2S4 eccentric spheres (NCS-ES) located inside channels, the metal sulfides of which were obtained through a template-free anion exchange method. By controlling the feeding weight of CW in the NiCo2S4 precursor solutions, the best electrochemical performance was achieved by mediating the synergetic effect between the carbon materials and the metal compounds. The optimized electrode material (NiCo2S4/CW-20) delivered a specific capacitance of 1472.1 F g−1 at a current density of 1 A g−1 and an 88.2% capacitance retention at 20 A g−1. The hybrid supercapacitor assembled using NiCo2S4/CW-20 as the cathode and activated carbon as the anode had a stable cyclic performance with a 102% capacitance retention after 5000 cycles at 10 A g−1. A high energy density of 69.03 Wh Kg−1 at a power density of 862.88 W kg−1 was also achieved. Our strategy to prepare CW-based electrode materials may provide new prospects for developing cost-effective and environmentally benign energy storage devices.