Ionically Conductive Elastic Polymer Binder for Ultrahigh Loading Electrode in High‐Energy‐Density Lithium Batteries

Abstract Despite the increasing demand for high‐energy‐density lithium batteries, the development of high‐mass‐loading electrodes remains challenged by structural instability and poor charge transfer. Herein, an ionically conductive elastic polymer (ICEP) binder, designed to enable the fabrication of ultrahigh mass‐loading Ni‐rich layered cathodes (LiNi 0.8 Co 0.1 Mn 0.1 O 2 , NCM811), is introduced. The ICEP binder integrates mechanical elasticity, strong adhesion, and ionic conductivity through diverse functional groups, addressing challenges in high‐mass‐loading electrode fabrication. Hydrogen bonding between the ICEP binder and NCM811 particles ensures uniform electrode morphology, forming a stable cathode–electrolyte interphase (CEI). This stable interface mitigates surface side reactions, suppresses phase transitions in NCM811, and improves long‐term electrochemical stability. Additionally, the ICEP binder enhances Li‐ion diffusivity, reduces interphase resistance, and promotes faster electrochemical kinetics, while preventing solvent‐drying‐induced cracking. As a result, high‐mass‐loading electrodes (62.4 mg cm⁻ 2 , 12.5 mAh cm⁻ 2 ) are successfully fabricated with the ICEP binder and demonstrate 94.6% capacity retention. Furthermore, a double‐stacked pouch‐type lithium metal full cell incorporating ICEP‐based cathodes achieves energy densities of 377.6 Wh kg cell ⁻ 1 and 1016.8 Wh L cell ⁻ 1 (including package materials), setting new benchmarks for lithium metal batteries. These findings establish ICEP as a highly effective binder for next‐generation high‐energy‐density batteries, offering a scalable and commercially viable solution for ultrahigh‐loading cathodes.