The effect of a Co–Al mixed metal oxide coating on the elevated temperature performance of a LiMn2O4 cathode material

Co–Al mixed metal oxide (CoAl-MMO) has been used for surface modification of LiMn2O4 spinel by means of a co-precipitation method in an attempt to improve the electrochemical performance of LiMn2O4 at elevated temperature. The surface modified materials were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrometry (EDS), Auger electron spectroscopy (AES) and galvanostatic charge–discharge cycling. After heat-treatment at 400 °C, the CoAl-MMO coated LiMn2O4 shows better capacity retention at both 25 °C and 55 °C than the pristine LiMn2O4. The enhancement in electrochemical performance is mainly attributed to the CoAl-MMO coating layer which has the synergistic effect of cobalt and aluminum oxide species and could block the direct contact between the spinel cathode material and electrolyte resulting in Mn dissolution decrease.