Hierarchical 3D Co3O4@MnO2 core/shell nanoconch arrays on Ni foam for enhanced electrochemical performance

In this work, we developed a novel three-dimensional (3D) core/shell Co3O4@MnO2 nanoconch arrays by a facile, stepwise hydrothermal approach. Core–shell Co3O4@MnO2 nanoconches were directly grown on a Ni current collector as an integrated electrode/collector. The electrochemical storage properties of as-prepared Co3O4@MnO2 hierarchical structure are investigated by testing them as anodes for both supercapacitors and Li-ion batteries. This unique 3D Co3O4/MnO2 hierarchical structure with enhanced active surface area provides a better interfacial/chemical distribution at the nanoscale, fast ion and electron transfer, and good strain accommodation. Thus, it has shown excellent electrochemical performances when it is used for supercapacitor, such as high specific capacitances 1,183.7 F g−1 at a current density of 1 A g−1 and long-term cycling stability (~92.5 % of capacitance retention up 3,000 cycles at 1 A g−1), which are better than that of the individual component of Co3O4 nanoconch arrays and MnO2 nanosheet arrays. The Co3O4@MnO2 core/shell nanoconch arrays are also tested as anode material for lithium-ion batteries, which also presents a high reversible capacity of 925 mAh g−1 at a rate of 120 mA g−1, good cycling stability, and rate capability.