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

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_0.8Co_0.1Mn_0.1O₂, 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.