The isomorphous MnO2@MnO2 core/shell nanostructures synthesized through a facile hydrothermal process showed remarkable electrochemical performance, i.e., a high specific capacitance with excellent cycling stability.

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A uniform dendritic NiCo 2 S 4 @NiCo 2 S 4 hierarchical nanostructure of width ≈100 nm is successfully designed and synthesized. From kinetic analysis of the electrochemical reactions, those electrodes function in rechargeable alkaline batteries (RABs). The dendritic structure exhibited by the electrodes has a high discharge-specific capacity of 4.43 mAh cm −2 at a high current density of 240 mA cm −2 with a good rate capability of 70.1% after increasing the current densities from 40 to 240 mA cm −2 . At low scan rate of 0.5 mV s −1 in cyclic voltammetry test, the semidiffusion controlled electrochemical reaction contributes ≈92% of the total capacity, this value decreases to ≈43% at a high scan rate of 20 mV s −1 . These results enable a detailed analysis of the reaction mechanism for RABs and suggest design concepts for new electrode materials.

A supercapacitor electrode of porous urchin-like MnCo2O4.5 hierarchical architectures demonstrated an outstanding rate capability and excellent cycling stability, which could be considered as a potential mixed transition metal oxide material for high-rate supercapacitors.