Uniform Radial Compression Enabling Densification of High‐Curvature Fiber Electrodes for High‐Rate Ah‐Level Energy Textiles

Fiber lithium-ion batteries (FLIBs), which can be woven into flexible energy textiles, are promising power sources for wearable electronics. However, increasing their cell-level energy density requires high-loading fiber electrodes that are limited by the porous, loosely packed structures formed during dip-coating, since conventional calendering cannot be applied to highly curved fibers without fracturing the coating. Here, we address this limitation by applying uniform radial compression around fiber electrodes through a flexible-roller calendering approach that uses an elastomer-wrapped steel roller, enabling efficient densification with substantially reduced structural disruption. X-ray computed tomography (CT) shows that calendering reduces porosity to 27.36% and removes large voids, along with improved particle packing and coating-collector contact. These microstructural optimizations effectively enhance transport kinetics, enabling calendered FLIBs to deliver a 72.70% increase in 4C capacity and improved cycling stability (300 cycles with retention over 87.41%). Their strengthened structural integrity affords reliable operation upon repeated deformations like bending and knotting, supports integration into Ah-level energy textiles, and allows conformal mounting on drone arms for high-power use. This work presents an effective, damage-free densification route for high-curvature fiber electrodes and provides a scalable microstructure-engineering approach for advancing wearable energy textiles and other deformable energy systems.