Low temperature performance of copper/nickel modified LiMn2O4 spinels

This study presents an evaluation of structural changes resulting from cycling modified copper/nickel LiMn2O4 spinels at 263 K. In situ synchrotron XRD shows that cycling LiMn2O4 at 263 K resulted in the formation of mixed cubic and tetragonal phases with a consequent lower capacity. The differential capacitance profile normally exhibiting two peaks at 298 K is modified, showing only one oxidation peak at 263 K in the 4 V region. The changes observed are attributed to interactions between Jahn-Teller active Mn3+ species and Li+ ions. These changes are not observed once copper/nickel modified spinels are being evaluated, because of the decrease in Mn3+ population. All the observed changes are fully reversible once the material is cycled back at 298 K.