Charging the LiCoO₂ (LCO) cathode to a higher voltage, for example 4.5 V compared to the commonly used 4.2 V, is now intensively pursued so as to achieve a higher specific capacity. However, it suffers severe surface structural degradation and detrimental interfacial side reactions between cathode and electrolyte, which lead to the fast capacity fading during long-term cycling. Here, a surface coating strategy was developed for the protection of 4.5 V LCO by constructing a manganese oxides (MOs) nanoshell around LCO particles, which was achieved through a solution-based coating process with success in controlling the growth kinetics of the coating species. We found that the introduction of the MOs nanoshell is highly effective in alleviating the organic electrolyte decomposition at the cathode surface, thus ensuring a much more stable LiF-rich cathode-electrolyte interface and an obvious lower interfacial resistance during electrochemical cycling. Meanwhile, this protection layer can effectively improve the structural stability of the cathode by hindering the cracks formation and structural degradation of LCO particles. Therefore, the MOs modified LCO exhibited excellent rate performance and a high discharge capacity retention of 81.5% after 100 cycles at 1 C compared with the untreated LCO (55.2%), as well as the improved thermal stability and cyclability at the elevated temperature. It is expected that this discovery and fundamental understanding of the surface chemistry regulation strategy provide promising insights into improving the reversibility and stability of LCO cathode at the cut-off voltage of 4.5 V.

为 LiCoO _2充电(LCO) 阴极到更高的电压，例如 4.5 V，与常用的 4.2 V 相比​​，现在被集中追求以实现更高的比容量。然而，它遭受严重的表面结构退化和正极和电解质之间有害的界面副反应，导致在长期循环过程中容量快速衰减。在这里，通过在 LCO 颗粒周围构建锰氧化物 (MO) 纳米壳，开发了一种表面涂层策略来保护 4.5 V LCO，这是通过基于溶液的涂层工艺实现的，并成功地控制了涂层物质的生长动力学。我们发现引入 MOs 纳米壳在缓解阴极表面的有机电解质分解方面非常有效，从而确保更稳定的富含LiF的阴极-电解质界面和电化学循环过程中明显更低的界面电阻。同时，该保护层可以通过阻碍LCO颗粒的裂纹形成和结构退化，有效提高正极的结构稳定性。因此，与未处理的 LCO（55.2%）相比，MOs 改性的 LCO 在 1 C 下循环 100 次后表现出优异的倍率性能和 81.5% 的高放电容量保持率，以及在高温下改善的热稳定性和循环性能。预计这一发现和对表面化学调节策略的基本理解为提高 LCO 正极在 4.5 V 截止电压下的可逆性和稳定性提供了有希望的见解。