Kim Hori, Jeong Moon-Ki, Kim Hyuk-Joon, Kim Youngsin, Kang Kisuk, Oh Joon Hak
School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.
Department of Materials Science and Engineering, Research Institute of Advanced Materials (RIAM), Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-742, Republic of Korea.
Small. 2025 Jul;21(30):e2502816. doi: 10.1002/smll.202502816. Epub 2025 May 28.
Improving the cycling stability in Ni-rich LiNiCoMnO (NCM) cathodes, particularly under high C-rates and elevated voltages, remains a significant challenge in lithium battery technology. A novel polymer coating based on lithium sulfonyl(trifluoromethane sulfonyl)imide methacrylate (LiMTFSI), a material commonly used in solid polymer electrolytes (SPEs), is applied to LiNiCoMnO (NCM811) cathodes. This coating improves electrochemical stability at high C-rates (2C and 4C) and voltages up to 4.5 V, compared to uncoated cathodes, enabling reduced charging times (e.g., 1 h at 1C to 15 min at 4C) while maintaining relatively enhanced cycling performance. Mechanistically, the coating helps suppress surface phase transitions to the rock-salt phase, mitigates transition metal dissolution, and facilitates lithium-ion transport at the cathode-electrolyte interface. These combined effects contribute to enhanced cycling durability under demanding conditions. Galvanostatic intermittent titration technique (GITT) analysis further supports that the coating promotes interfacial lithium-ion conduction without acting as an insulating barrier. Additionally, the coated NCM811 electrodes exhibit improved rate performance. This study shows that repurposing SPE-derived monomers as cathode surface modifiers provides a practical route to improving rapid-charging capability, energy utilization, and long-term operational stability in lithium batteries.
提高富镍LiNiCoMnO（NCM）阴极的循环稳定性，尤其是在高倍率充电和高电压下，仍然是锂电池技术中的一项重大挑战。一种基于甲基丙烯酸锂磺酰基（三氟甲磺酰基）亚胺（LiMTFSI）的新型聚合物涂层被应用于LiNiCoMnO（NCM811）阴极，LiMTFSI是一种常用于固体聚合物电解质（SPEs）的材料。与未涂层的阴极相比，这种涂层在高倍率充电（2C和4C）以及高达4.5 V的电压下提高了电化学稳定性，能够缩短充电时间（例如，从1C时的1小时缩短至4C时的15分钟），同时保持相对增强的循环性能。从机理上讲，该涂层有助于抑制表面向岩盐相的相变，减轻过渡金属溶解，并促进阴极-电解质界面处的锂离子传输。这些综合效应有助于在苛刻条件下提高循环耐久性。恒电流间歇滴定技术（GITT）分析进一步支持了该涂层促进界面锂离子传导而不充当绝缘屏障的观点。此外，涂覆的NCM811电极表现出改善的倍率性能。这项研究表明，将SPE衍生的单体重新用作阴极表面改性剂为提高锂电池的快速充电能力、能量利用率和长期运行稳定性提供了一条切实可行的途径。
