Extreme fast charging characteristics of zirconia modified LiNi0.5Mn1.5O4 cathode for lithium ion batteries
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LiNi0.5Mn1.5O4 is a promising high-voltage cathode for lithium-ion battery fast charging applications. Aware of its electrochemical stability issues, the material's surface is modified with small amounts of zirconia (ZrO2) ranging from 0.5 to 2 wt% using a scalable ball milling process. The advantage of the coating has been demonstrated in electrochemical measurements performed at room temperature and 55 ?C, and in cells discharged under high-rate conditions up to 80C. Of significance, the material coated with 1.0 wt% ZrO2 has been cycled at the 40C rate for over a thousand cycles and retains 86% of its initial capacity. The material with 2.0 wt% ZrO2 modification preserves 76% of its initial capacity when cycled at the 40C rate and 55 ?C. The coated materials have shown excellent cycling stability when subjected to 6C (10-min) fast charging and C/3 discharging for 300 cycles. Compared to the uncoated material, the interfacial resistance of the zirconia modified LiNi0.5Mn1.5O4 has been found to be much lower and does not significantly increase with increasing the coating amount. However, the electrochemical performances are still partly limited by both interfacial resistance at the beginning of charge and electrolyte diffusivity, particularly under higher rate cycling conditions. Overall, the strategy of ZrO2 surface modification applied to LiNi0.5Mn1.5O4 unveils the potential that the material could play in extreme fast charged electric vehicles.