Enhanced electrochemical performance of Li-rich layered oxide cathodes via La-Co surface coating

초록

Li-rich layered oxides are attractive cathode materials for lithium-ion batteries, but their use is hindered by voltage decay, capacity fading, and phase transition. Here, we report a La-Co surface coating strategy applied to Li[Li0.2Mn0.5Ni0.3]O2 (LMNO). The coated electrodes (LMNO_0.1 and LMNO_0.2) show markedly enhanced cycling stability and rate capability compared to uncoated LMNO and Co-containing Li[Li0.2Mn0.54Ni0.13Co0.13] O2 (LMNCO). At 0.1C, LMNO_0.1 retains 93.5 % of its initial capacity (241 mAh g-1) after 100 cycles, while LMNO_0.2 achieves 88.7 %. Even at higher rates (0.5C charge/1C discharge), the coated samples maintain superior performance, with capacities of 191 and 180 mAh g-1 after 200 cycles. Rate capability tests confirm improved Li+ transport and reduced interfacial polarization, particularly for LMNO_0.2 at 5C. Raman analysis reveals significant suppression of the layered-to-spinel phase transition in coated electrodes. This work highlights La-Co surface modification as an effective approach to stabilize Li-rich layered oxides for high-energy lithium-ion batteries.

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