Ah‐Level Large‐Format Fiber‐Shaped Lithium‐Ion Batteries Enabled by Effective Field Homogenization

Abstract Large‐format fiber‐shaped lithium‐ion batteries (L‐FLIBs) hold great promise for next‐generation flexible and wearable electronics but suffer significant cell polarization and insufficient active material utilization after scaling up. The heterogeneous spatial electric field distribution fundamentally affects the electrochemical behavior and jeopardizes the performance of L‐FLIBs, yet its influence on 1D fiber structures remains unexplored. Here, the electron transport mechanisms are systematically investigated and develop an optimized dual‐terminal cell configuration for field homogenizing. Through equivalent circuit modeling and experimental validation, it is revealed that strategic electron collection terminal design establishes symmetric electric fields along the fiber length, effectively addressing the fundamental challenge of electrochemical heterogeneity and enhancing the redox kinetics for L‐FLIBs. Thereby, a 60% internal resistance reduction is achieved and successfully fabricated a 10‐m‐long L‐FLIBs with an unprecedented 1 Ah high capacity for a single fiber cell. The practical capability of this design is demonstrated by integrating large‐format batteries into a fabric power bank for portable electronics.