High Temperature Performance of Surface-Treated Li[sub 1.1](Ni[sub 0.15]Co[sub 0.1]Mn[sub 0.55])O[sub 1.95] Layered Oxide

Abstract

The electrochemical performance of pristine and AlF3AlF3 -coated Li1.1Ni0.15Co0.1Mn0.55O1.95Li1.1Ni0.15Co0.1Mn0.55O1.95 cathodes is reported for cells cycled at 25 and 55°C55°C . In a half-cell configuration, a nanolayer coating of AlF3AlF3 on the Li1.1Ni0.15Co0.1Mn0.55O1.95Li1.1Ni0.15Co0.1Mn0.55O1.95 stabilizes the capacity on cycling. However, in cell tests with metallic lithium anodes, the initial coulombic efficiency decreased slightly at both 25 and 55°C55°C for AlF3AlF3 -coated Li1.1Ni0.15Co0.1Mn0.55O1.95Li1.1Ni0.15Co0.1Mn0.55O1.95 in comparison to the pristine material. For cells constructed with graphite instead of lithium anodes, the capacity stability improved with cycling for the coated cathode materials. Transition-metal dissolution was more pronounced for the AlF3AlF3 -coated sample when stored at 55°C55°C in electrolytes. For both the pristine and AlF3AlF3 -coated samples, there was no extra capacity loss due to the elevated temperature. Around 10% capacity gain of the cathode materials at elevated temperature is assumed to be due to improved thermodynamic activation.