Enhanced Cycling Stability of NCM811 Cathodes at High C‐Rates and Voltages via LiMTFSI‐Based Polymer Coating

Abstract Improving the cycling stability in Ni‐rich LiNi x Co y Mn 1−x−y O 2 (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 LiNi 0.8 Co 0.1 Mn 0.1 O 2 (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 int…