The influence of dopants on the electrochemical behavior of lithium manganese spinel

Undoped LiMn2O4 and lithium manganese oxide spinels, LiMxMn2-xO4, with partial replacement of manganese by aluminum, cobalt, chrome, lithium, nickel and zinc, were prepared and the effect of extended cycling on the crystal structure was investigated. In the case of titanium and zinc no single phase products were obtained. Initial capacity decreases with increasing content and decreasing valency of the dopant. Cycling behavior is significantly improved for Al, Co, Cr, Ni and Li, compared to LiMn2O4. LiMxMn2-xO4 is discharged in a single phase reaction in the upper potential range around 4100 mV vs. Li/Li+, whereas pure LiMn2O4 exhibits a two phase behavior. The significant broadening of peaks in plots of differential capacity and change in shape of the voltage profile upon extended cycling of LiMn2O4 is not observed in doped spinels.