Spinel LiNi_0·5Mn_1·5O₄ (LNMO), though being considered as a promising cathode material because of their high energy and power density, always suffers from rapid capacity deterioration due to the Jahn-Teller effect and severe leakage of Mn ions into electrolytes at elevated temperatures. In this work, Li₃BO₃ (LBO) formed from slow hydrolysis of triethyl borate was coated on the surface of LiMn_1·5Ni_0·5O₄ materials prepared through a modified wet-chemistry method. Our results put an emphasis on the strong chemical interactions between the external LBO coating layer and the internal LNMO core induced by a high-temperature thermal treatment; owing to the favorable solid-solid interfacial interaction, the presence of the relatively oxidative Li₃BO₃ layer was found to diminish the population of the oxygen vacancy and minimize the unstable Mn³⁺ species in the LNMO active materials, which thus could alleviate the adverse Jahn-Teller distortion and enhance the structural stability. Moreover, as a coating layer, the LBO could prevent direct interaction between the cathode active materials and the electrolyte; as such, the etching of the LNMO cathode materials by the decomposition products of electrolytes such as HF and the leakage of active metal species were inhibited effectively. Besides, the LBO itself is a highly conductive ionic conductor, which thus could enable fast Li⁺ cation diffusion on the cathode. On this basis, a significant improvement was observed in the high-rate cycling performance for thus coated LNMO cathode materials. The bare LNMO electrode failed within merely 300 cycles. In contrast, our optimal sample LBO_2%@LNMO with 2 wt% of LBO delivers a high discharge specific capacity of 127 mAh g⁻¹, which accounts for 92% of its initial capacity after 500 cycles at 1C in the range of 3.5–4.99 V; when cycling at 10 C, it displays an initial discharge specific capacity of 111 mAh g⁻¹ and maintains 85 mAh g⁻¹ after 1000 cycles. Our work demonstrates that in addition to behaving as a physical protection layer, the introduction of the ionic conductive Li₃BO₃ coating layer could also modify the local composition of the spinel-type LNMO through strong interfacial chemical reaction, which thus could profoundly enhance the structural integrity and high-rate cycling stability.

尖晶石LiNi _0·5 Mn _1·5 O ₄（LNMO）尽管因其高能量和高功率密度而被认为是有前途的正极材料，但由于Jahn-Teller效应和Mn的严重泄漏，总是会导致容量快速下降离子在高温下变成电解质。在这项工作中，由硼酸三乙酯缓慢水解形成的Li ₃ BO ₃（LBO）涂覆在LiMn _1·5 Ni _0·5 O _{4的表面上}通过改进的湿化学方法制备的材料。我们的结果强调了高温热处理引起的外部LBO涂层与内部LNMO核之间的强化学相互作用；由于有利的固-固界面相互作用，发现相对氧化的Li ₃ BO ₃层的存在减少了氧空位的数量，并使不稳定的Mn ³⁺最小化。LNMO活性材料中的这些物种，从而可以减轻不利的Jahn-Teller畸变并增强结构稳定性。此外，作为涂层，LBO可以防止正极活性物质与电解质之间的直接相互作用。因此，有效地抑制了电解质如HF的分解产物对LNMO阴极材料的蚀刻以及活性金属物质的泄漏。此外，LBO本身是一种高导电性的离子导体，因此可以实现Li ⁺阳离子在阴极上的快速扩散。在此基础上，观察到如此涂覆的LNMO阴极材料的高倍率循环性能的显着改善。裸露的LNMO电极仅在300个循环内失效。相反，我们的最佳样本杠杆收购_2％具有2 wt％LBO的@LNMO可提供127 mAh g ^-1的高放电比容量，在1 C在3.5-4.99 V范围内经过500次循环后，其初始容量占其初始容量的92％；当在10 C循环时，它的初始放电比容量为111 mAh g ^-1，在1000次循环后仍保持85 mAh g ^-1。我们的工作表明，除了起到物理保护层的作用外，引入离子导电Li ₃ BO ₃涂层还可以通过强烈的界面化学反应来改变尖晶石型LNMO的局部组成，从而可以显着增强表面活性。结构完整性和高循环稳定性。