An Electrode-Less Fiber Battery With 600 Wh/L-Level Volumetric Energy Density Enabled by Dynamic Deposition Chemistry

Aqueous fiber batteries are essential for next-generation wearable electronics due to their inherent safety, low cost, and environmental friendliness. However, the low volumetric energy density (<100 Wh/L), stemming from the contradiction of insufficient spatial utilization and limited flexibility inherent to the pre-coated fiber electrodes, significantly hinders their practical applications. Here, we introduce an ultrathin, electrode-less fiber battery based on the dynamic deposition chemistry to decouple volumetric energy density from mechanical robustness. This battery addresses the core inefficiency of pre-coated fiber batteries through dynamic deposition chemistry that dissolves redox-active materials directly into the electrolyte, thereby eliminating the need for pre-coated electrodes. This intrinsic design minimizes inactive material volume and facilitates on-demand electrochemical deposition during operation. Thus, the resulting fiber battery achieves a high volumetric energy density of 612 Wh/L and an ultrathin diameter of 130 µm. Furthermore, its dynamic stiffness is reduced by three orders of magnitude compared to pre-coated counterparts. This study unveils a new technological pathway for fiber batteries with high volumetric energy density. Simultaneously, it establishes a novel, material-efficient architectural paradigm that seamlessly integrates into high-performance textiles, enabling future wearable devices.