Structure and Interfacial‐Stable Binder Engineering Enables High‐Rate Capability of NCM811 Cathodes at 4.6 V

ABSTRACT High‐voltage cathodes improve the energy density of lithium metal batteries (LMBs). However, cathodes constructed by high‐nickel layered oxide severely suffer from structural degradation and interfacial instability under high‐voltage condition. Herein, an alkali lignin cross‐linked acrylonitrile and acrylic acid copolymer is developed as 3D cathode binder (PNAL), which effectively scavenges oxygen radicals generated under high‐voltage, suppresses the irreversible dissolution of transition metal ions, and stabilizes both the electrode‐electrolyte interface and the cathode structure. As a result, the PNAL‐based LiNi 0.8 Mn 0.1 Co 0.1 O 2 LMB achieve a high‐capacity retention of 75.7% after 300 cycles at 4.6 V under 3C. Furthermore, an Ah‐scale pouch cell fabricated by PNAL delivers an energy density of 376.5 Wh kg −1 and retains 81.7% capacity after 100 cycles at 4.6 V. This work provides a promising binder strategy to construct high‐voltage cathodes for next‐generation LMBs.