Enhanced cycling performance of spinel LiMn₂O₄ coated with ZnMn₂O₄ shell

ZnMn₂O₄ shell-coated LiMn₂O₄ was prepared by a simple routine that the mixture of LiMn₂O ₄ and ZnO were heated at 750 °C. The structure and electrochemical performance of as-prepared powder compared with the pure LiMn₂O₄ were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDAX), and galvanostatic charge-discharge testing, respectively. The results of XRD, SEM, and EDAX show that ZnMn₂O₄ is formed on the surface of LiMn₂O₄ particles. Charge-discharge testing reveals that ZnMn₂O₄ shell-coated LiMn₂O₄ greatly enhances the capacity retention of the spinel LiMn₂O₄. Furthermore, the modified LiMn₂O₄ shows significant enhancement in cycling stability at rates from 0.5 C to 12 C. It is found that the improved cycling performance and rate capability of the modified LiMn ₂O₄ are attributed to the effective decrease of manganese dissolution from spinel structure because of ZnMn₂O₄ shell coated on the surface of LiMn₂O₄ particle.