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.