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 NiCo 2 S 4 @TiO 2 nanorod arrays/carbon cloth (NiCo 2 S 4 @TiO 2 @CC) have been fabricated, via a two-step hydrothermal method. Comprehensive structural and compositional analyzes are performed to understand the effects of the NiCo 2 S 4 shell on the TiO 2 core. Such core–shell arrays structure can significantly provide abundant electroactive sites for redox reactions, convenient ion transport paths, and favorable structure stability. The NiCo 2 S 4 @TiO 2 @CC electrode represents a splendid specific capacitance (650 F g −1 at 1 A g −1 ) and enhanced cycling stability (capacitance retention of 97% over 10 000 cycles at 5 A g −1 ). Additionally, the assembled NiCo 2 S 4 @TiO 2 @CC//CNT@CC solid-state asymmetric supercapacitors exhibit a maximal energy density of 0.6 mWh cm −3 at 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 NiCo 2 S 4 @TiO 2 @CC presented in this work are applicable for the development of electrode materials in energy storage devices.