Core−shell coaxially structured NiCo ₂ S ₄ @TiO ₂ nanorod arrays as advanced electrode for solid-state asymmetric supercapacitors

Abstract

An integrated electrode of core-shell coaxially structured NiCo₂S₄@TiO₂nanorod arrays/carbon cloth (NiCo₂S₄@TiO₂@CC) have been fabricated, via a two-step hydrothermal method. Comprehensive structural and compositional analyzes are performed to understand the effects of the NiCo₂S₄shell on the TiO₂core. Such core-shell arrays structure can significantly provide abundant electroactive sites for redox reactions, convenient ion transport paths, and favorable structure stability. The NiCo₂S₄@TiO₂@CC electrode represents a splendid specific capacitance (650 F g^-1at 1 A g^-1) and enhanced cycling stability (capacitance retention of 97% over 10 000 cycles at 5 A g^-1). Additionally, the assembled NiCo₂S₄@TiO₂@CC//CNT@CC solid-state asymmetric supercapacitors exhibit a maximal energy density of 0.6 mWh cm^-3at 32.4 W cm^-3, and topping cycling stability (85% capacitance retention after 5000 cycles at 5 mA cm^-2). The results demonstrate that the well-designed NiCo₂S₄@TiO₂@CC presented in this work are applicable for the development of electrode materials in energy storage devices.