Effect of the Cr2O3 coating on electrochemical properties of spinel LiMn2O4 as a cathode material for lithium battery applications

The effect of the Cr2O3 coating on the charge–discharge cycling performance of spinel powder (LiMn2O4) is investigated in the range of 3.5–4.5 V at 1 C. The Cr2O3 coating on the surface of the spinel powder is carried out using the solution method, followed by 500 °C sintering for 6 h in air. Powder X-ray diffraction pattern of the Cr2O3-coated spinel LiMn2O4 shows that the Cr2O3 coating medium is not incorparated in the spinel bulk structure. SEM results show that the Cr2O3 coating particles are homogenously distributed on the surface of LiMn2O4 powder particles. XPS results shows tahat the Cr2O3 coating causes increasing of Mn(IV) concentration at the surface of LiMn2O4 particles. While the bare LiMn2O4 delivered an average capacity loss of 0.22% per cycle in 70 cycles, the 0.5 wt.%, 1 wt.%, 2 wt.% and 3 wt.% Cr2O3-coated LiMn2O4 only showed the average loss of 0.12%, 0.08%, 0.11% and 0.08% per cycle, respectively. The improvement of electrochemical performance is attributed to suppression of Mn2+ dissolution into electrolyte via Cr2O3 layer.