The limited lithium-ion diffusion and depressed cathode/electrolyte interface stability greatly deteriorate the cycling and rate performance of lithium-ion batteries, especially when they are operated at elevated temperatures (≥50 °C) and/or high charge cutoff voltages (>4.4 V vs Li/Li⁺). Herein, we proposed a demand-oriented surface coating strategy by introducing multifunctional LiBO₂/LiAlO₂ layers onto the surface of LiNi_0.5Co_0.2Mn_0.3O₂ (NCM) single crystals, in which the middle LiAlO₂ layer is designed to ensure intimate contact with NCM to prevent the direct contact between the cathode and electrolyte and thus strengthen the cathode surface structure. The outmost LiBO₂ is expected to serve as an isolation layer to improve the Li⁺ transportation and solid electrolyte interface stability. LiBO₂/LiAlO₂ (BA-NCM)- and LiBO₂ (B-NCM)-coated NCM were demonstrated and systematically studied by several experimental techniques. Benefiting from the demand-oriented coating strategy, BA-NCM shows the much-improved rate and cycling performances as compared with B-NCM and bare NCM at both 25 and 55 °C. Especially, when operated at 55 °C, the capacity retention of BA-NCM after 500 cycles at 1 C is as high as 66.3%, while it is 26.9% for B-NCM.

中文翻译：

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通过LiBO ₂ / LiAlO ₂双重修饰策略提高单晶LiNi _0.5 Co _0.2 Mn _0.3 O ₂阴极的高温和高压性能

受限的锂离子扩散和降低的阴极/电解质界面稳定性会严重破坏锂离子电池的循环和速率性能，尤其是在高温（≥50°C）和/或高充电截止电压（> 4.4）下运行时V vs Li / Li ⁺）。本文中，我们通过在LiNi _0.5 Co _0.2 Mn _0.3 O ₂（NCM）单晶的表面上引入多功能LiBO ₂ / LiAlO ₂层，提出了一种面向需求的表面涂覆策略，其中中间的LiAlO ₂层的设计可确保与NCM紧密接触，以防止阴极与电解质直接接触，从而增强阴极表面结构。预计最外层的LiBO ₂将用作隔离层，以改善Li ^+的传输和固体电解质界面的稳定性。LiBO ₂ / LiAlO ₂（BA-NCM）-和LiBO ₂（B-NCM）涂层的NCM通过几种实验技术进行了演示和系统地研究。得益于以需求为导向的涂层策略，BA-NCM在25和55°C下与B-NCM和裸NCM相比，显示出大大提高的速率和循环性能。特别是在55°C下工作时，BA-NCM在1 C下经过500次循环后的容量保持率高达66.3％，而B-NCM为26.9％。