Improving the high-temperature performance of LiMn2O4 spinel electrodes by coating the active mass with MgO via a sonochemical method

LiMn2O4 spinel coated sonochernically with MgO was studied as an active mass in composite cathodes in standard Li electrolyte solutions for Li-ion batteries at 60 degreesC. Solutions comprising 1 M LiPF6 in a mixture of ethylene, dimethyl, and diethyl carbonates (EC-DMC-DEC; 2:2:1) were used. It was possible to obtain LiMn2O4 particles fully covered by porous magnesia films that allow a free transport of Li-ions. Electrodes comprising LiMn2O4, modified by MgO showed a higher capacity retention compared to the electrodes comprising an uncoated active mass, specially at elevated temperatures. We suggest that the presence of an MgO film on the surface of the LiMn2O4 particles, reduces the detrimental effect of HF contamination present in LiPF6 solutions, reduces the electrodes' impedance and improves their kinetics. (C) 2003 Elsevier B.V. All rights reserved.