Extra Capacity Retention of Lithium‐Ion Battery Enabled by Metallized Polymer Current Collector: Enhanced Interfacial Electric Contact due to Coupled Mechano‐Electrochemical Effects

The growing demand for high energy density lithium‐ion batteries (LIBs) has propelled the development of metallized polymer current collectors (MPCCs) to reduce battery weight. Existing studies predominantly focus on MPCCs’ abuse tolerance, while their mechano‐electrochemical coupling behavior and dynamic evolution of interfacial contact with active materials remain largely underexplored. Here, this comparative work studies MPCCs and metallic current collectors via multi‐modal characterization and a coupled finite element mechanical‐pseudo 3D electrochemical model. It is revealed that MPCCs’ polymeric interlayer mitigates irreversible plastic deformation, sustaining superior interfacial electrical integrity. Pouch cells with MPCC deliver a ∼1% initial capacity increase and 6.69% higher discharge capacity retention after 300 cycles at 1C. Furthermore, this work establishes a robust mechano‐electrochemical simulation framework, providing critical design guidelines for next‐gen high energy LIBs adopting MPCCs.