A procedure for specific charge and cycling performance measurements on LiMn 2 O 4 spinels for lithium-ion batteries

Abstract

A procedure for determining the specific charge and the cycling performance of lithium manganese oxide spinels (LiMn2O4) for rechargeable lithium-ion batteries has been developed. Measurements were made in two-electrode electrochemical test cells with an internal arrangement resembling that of coin cells, with either metallic lithium or a graphite composite counter electrode. Applying the procedure to various LiMn2O4 spinels with different degrees of manganese substitution, Li1+yMn2 −yO4 (0.05≤y≤0.1), and different surface coatings, we observed an increase of the spinel cycle life with an increasing degree of manganese substitution, at the expense of a small decrease of the specific charge. The influence of the type of counter electrode on the specific charge measurements was examined. Furthermore, we investigated the influence of the temperature, 25 °C vs. 55 °C, on the specific charge and the cycling performance of the spinels with different degrees of manganese substitution. A survey of the combined effects of the counter electrode and the temperature on the specific charge measurements is given.