Coating effect of Al2O3 on ZnMn2O4 cathode surface for lithium ion batteries

Abstract

Abstract Zinc manganate (ZnMn2O4) with cluster spherical structure is prepared by low temperature coprecipitation method, and then coated with nano-sized Al2O3 via a wet chemical process. The as-prepared ZnMn2O4(ZMO), Al2O3-coated ZnMn2O4(ZMO-AlO) are characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The scanning electron microscopy shows both the ZMO and ZMO-AlO form cluster spherical structure. X-ray photoelectron spectroscopy confrms that ZMO-AlO covered with a layer of Al2O3 particles. The ZMO and ZMO-AlO exhibit improved electrochemical performance. The initial discharge capacity is enhanced to 1228 mAh·g− 1 after the Al2O3 coating compared to the ZMO material that has an initial discharge capacity of 1140 mAh·g− 1. During the second charging and discharging process, the specific capacities of ZMO-AlO samples were 763 and 788 mAh·g− 1 respectively, with a coulombic efficiency of 96.8%. The charge-discharge specific capacities of ZMO samples are 760 and 715 mAh·g− 1 respectively, with a coulombic efficiency of 94.1%. By comparing the first and second charge discharge performance of ZMO and ZMO-AlO at a current density of 100 mA·g− 1, it can be found that ZnMn2O4 modified by Al2O3 coating has better electrochemical lithium storage performance.