In this paper, a highly ordered three-dimensional Co₃O₄@MnO₂ hierarchical porous nanoneedle array on nickel foam is fabricated by a facile, stepwise hydrothermal approach. The morphologies evolution of Co₃O₄ and Co₃O₄@MnO₂ nanostructures upon reaction times and growth temperature are investigated in detail. Moreover, the as-prepared Co₃O₄@MnO₂ hierarchical structures are investigated as anodes for both supercapacitors and Li-ion batteries. When used for supercapacitors, excellent electrochemical performances such as high specific capacitances of 932.8 F g⁻¹ at a scan rate of 10 mV s⁻¹ and 1693.2 F g⁻¹ at a current density of 1 A g⁻¹ as well as long-term cycling stability and high energy density (66.2 W h kg⁻¹ at a power density of 0.25 kW kg⁻¹), which are better than that of the individual component of Co₃O₄ nanoneedles and MnO₂ nanosheets, are obtained. The Co₃O₄@MnO₂ NAs are also tested as anode material for LIBs for the first time, which presents an improved performance with high reversible capacity of 1060 mA h g⁻¹ at a rate of 120 mA g⁻¹, good cycling stability, and rate capability.

With the development of flexible electronic devices, the research on flexible storage devices has received considerable attention. In this paper, we designed novel tin nanoparticles encapsulated in carbon nanotubes (TNEC) arrays on carbon cloth prepared by a facile carbon reduction route as a flexible anode for lithium-ion batteries. The TNEC electrode shows a high areal capacity (2.15 mAh cm⁻²) when the current density is 0.1 mA cm⁻², Meanwhile, a good cycling performance (84 % of initial capacity) is achieved after 80 charge–discharge cycles, which could be attributed to the high theoretical capacity of metal tin and the tin encapsulated in carbon nanotubes structure that improves the electrical conductivity and structure stability.