Enhancing High-Temperature and High-Voltage Performances of Single-Crystal LiNi0.5Co0.2Mn0.3O₂ Cathodes through a LiBO₂/LiAlO₂ Dual-Modification Strategy

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 LiBO 2 /LiAlO 2 layers onto the surface of LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM) single crystals, in which the middle LiAlO 2 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 LiBO 2 is expected to serve as an isolation layer to improve the Li + transportation and solid electrolyte interface stability. LiBO 2 /LiAlO 2 (BA-NCM)- and LiBO 2 (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.