Enhanced electrochemical performance of hybrid SnO2@MOx (M = Ni, Co, Mn) core-shell nanostructures grown on flexible carbon fibers as the supercapacitor electrode materials

In this study, hierarchical SnO2@MOx (SnO2@NiO, SnO2@Co3O4, and SnO2@MnO2) heterostructures grown on carbon cloth (CC) for high performance supercapacitors were fabricated by a two-step solution-based method involving a hydrothermal process and a chemical bath deposition, which utilizes the better electronic conductivity of SnO2 nanosheets as the supporting backbone to deposit MOx for supercapacitor electrodes. Particularly, the as-formed SnO2@MOx heterostructure electrodes showed better electrochemical performance than bare SnO2 nanosheets. Remarkably, the SnO2@MnO2 heterostructure electrode showed the highest discharge areal capacitance (980 mF cm(-2) at 1 mA cm(-2)), good rate capability (still 767 mF cm(-2) at 20 mA cm(-2)), and excellent cycling stability (similar to 21.9% loss after 6000 repetitive cycles at a charge-discharge current density of 1 mA cm(-2)). The enhanced pseudocapacitive performance was mainly attributed to its unique hybrid structure, which provides fast ion and electron transfer, a large number of active sites, and good strain accommodation. The excellent electrochemical performance of the as-obtained heterostructures will undoubtedly make these hybrid structures attractive for high performance supercapacitors with high power and energy densities.