Multicationic Modulation Combining With Epitaxial Entropy-Tailored Coating Unlocking 4.65 V Operation of Chemomechanically Stable LiCoO2 Cathode

en This link goes to a English section zh This link goes to a Chinese section To meet the escalating demand for high-performance LiCoO 2 (LCO) cathodes, elevating the charging cut-off voltage becomes highly imperative to achieve markedly enhanced specific capacities. However, high-voltage operation is always accompanied by structural instability, notably deleterious bulk phase transitions and severe interfacial degradation. Herein, we propose a collaborative strategy that integrates a medium-entropy (Mg, Eu, and W) doped bulk architecture with an in situ formed epitaxial entropy-assisted MoB surface coating, which effectively suppresses the detrimental surface-initiated structural degradation, enabling a robust, high-voltage-tolerant LCO cathode. The synergistic co-doping of Mg, Eu, and W not only strengthens the structural framework without crack formation but also curtails lattice oxygen loss while accelerating Li + diffusion kinetics. Moreover, the in situ generation of an entropy-stabilized MoB coating provides exceptional resistance against corrosion induced by electrolyte decomposition. Using this design principle, the LCO featuring surface-to-bulk synergistic modification is endowed with exceptional wide-temperature-tolerant electrochemical stability at a high voltage of 4.65 V, delivering an outstanding rate capability of 153.3 mAh g −1 at 5C and long-term cycling stability with 84.4% capacity retention after 400 cycles. Our contribution hugely advances the high-voltage LCO cathodes toward the practical commercialization of high-energy-density lithium-ion batteries. 摘要 en This link goes to a English section zh This link goes to a Chinese section 随着高能量密度锂离子电池的发展,提高LiCoO 2 (LCO)正极材料的充电截止电压是提升其比容量的有效途径。然而,高电压运行过程中不可避免地会引发体相结构失稳、相变以及电极/电解液界面持续劣化等问题,严重制约其循环寿命和实际应用。针对上述问题,本文提出了一种协同调控策略,通过构建Mg,Eu和W中熵共掺杂体相结构,并原位形成外延熵辅助MoB表面包覆层,实现了LCO正极材料的表面-体相协同稳定。多元素协同掺杂不仅增强了主体晶体结构稳定性,抑制了层状结构滑移和晶格氧损失,同时加快了Li + 扩散动力学;原位形成的熵稳定MoB外延包覆层则有效抑制了电解液腐蚀、Co溶解及界面副反应,提高了电极/电解液界面的稳定性。得益于体相与表面的协同调控,所得表面-体相协同改性的LCO正极在4.65 V高截止电压下表现出优异的宽温区电化学性能,在5C倍率下可提供153.3 mAh g −1 的放电容量,并在1C循环400次后仍保持84.4%的容量保持率。本研究为开发兼具高能量密度和长循环寿命的新一代高电压LCO正极材料提供了一种有效的设计思路。