Synthesis and electrochemical performances of ZnO/MnO₂ sea urchin-like sleeve array as anode materials for lithium-ion batteries

MnO₂ is electrodeposited onto ZnO nanorod array grown on Ni foil, forming a binder-free ZnO/MnO₂ composited electrode. XRD, EDS, SEM and TEM are used to analyze the phase and microstructure of this composite. Burr-like MnO₂ nanoflakes grows on ZnO nanorod array, the top of the composite is hollow and at the bottom exists ZnO large block core as an internal support, forming ZnO/MnO₂ sea urchin-like sleeve array. As anode material for lithium ion batteries, ZnO/MnO₂ sleeve array exhibits higher discharge capacity and coulombic efficiency, better rate performance and cycling stability than single ZnO nanorod array or directly electrodepsited MnO₂, and the composite effect is very remarkable. After 100 cycles, the discharge capacity of ZnO/MnO₂ still reaches 1259 mA h g⁻¹, and coulombic efficiency surpasses 98%, higher than those of ZnO nanorod array (111 mA h g⁻¹) and directly electrodeposited MnO₂ (507 mA h g⁻¹). The improvement of the electrochemical performances is due to the unique sea urchin-like sleeve array architecture. MnO₂ burr tube shell structure leads to high electrochemical activity while the internal ZnO core support ensures good structure stability. The gradually opening of sea urchin-like sleeve during the cycling further enhances the electrochemical activity of MnO₂, stabilizing and increasing electrochemical performances of the ZnO/MnO₂ composite