New Insights for the Abuse Tolerance Behavior of LiMn2O4 under High Cut-Off Potential Conditions

The further development of lithium-ion batteries is often desired to obtain higher capacities by charging to higher potentials. However, such a high potential (>4.3 V) will inevitably result in capacity loss of the LiMn2O4 cathode material over numerous cycles. In this work, degradation mechanisms of LiMn2O4 electrode cycled at different charge cut-off potentials (4.4, 4.5, 4.6, 4.7, and 4.8 V vs. Li/Li+, respectively) have been investigated. It is found that the capacity degraded seriously after aging cycles at the cut-off potentials (<4.6 V), especially at 4.4 V. Remarkably, a thicker cathode-electrolyte interface (CEI) film on the cathode surface can be observed when the potential reached 4.7 and 4.8 V. Thus, two degradation mechanisms are proposed, which are also verified by the calculation of the diffusion coefficient of Li+ ions (D-Li(+)). This work demonstrates the relationship between the capacity fade and cut-off potentials and provides a useful guidance for other cathode materials with high-voltage operation.