Hierarchical manganese cobalt sulfide core–shell nanostructures for high-performance asymmetric supercapacitors

Abstract High electrical conductivity and rational design of structures are two crucial routes to improving the electrochemical performance of electrode materials. However, highly conductive electrode materials with short ion-transport paths remain a challenge in energy storage. Here, we propose manganese cobalt sulfide (MnCo 2 S 4 ) nanowire wrapping by a flocculent shell layer using a facile hydrothermal method with post-sulfurization treatment. The resultant MnCo 2 S 4 electrode employed for supercapacitor delivered a remarkable specific capacitance of 2067 F g −1 at the current density of 1 A g −1 , good rate capability, and excellent cycling stability. Moreover, an asymmetric supercapacitor device was successfully assembled using MnCo 2 S 4 and reduced graphene oxide (rGO) as electrodes, achieving a high energy density of 31.3 W kg −1 at a power density of 800 W kg −1 . With such outstanding electrochemical performance, this asymmetric supercapacitor device holds great potential in developing high-energy-storage applications.