Mechanics-coupled design of fiber-shaped batteries for wearable systems: architectures, interfaces, and scalable integration

Fiber-shaped batteries have moved beyond proof-of-concept demonstrations and are increasingly being treated as load-bearing, deformable power components for electronic textiles. Their practical performance, however, is governed by a coupled problem: electrochemical reactions must remain spatially uniform while slender multilayer structures are bent, twisted, stretched, woven, washed, and repeatedly loaded. This mini review examines recent advances from a mechanics-centered perspective. It first relates coaxial, parallel, twisted, and spring-like architectures to strain distribution, interfacial contact, current-collection distance, and failure localization. It then discusses how fibrous current collectors, binder-free active layers, porous electrodes, and gel electrolytes regulate ion transport and suppress delamination or metal-dendrite damage. Progress in lithium-ion, aqueous zinc-ion, zinc-air, sodium-based, and metal-gas fiber batteries is compared in terms of the trade-off among energy density, safety, flexibility, and manufacturability. Particular attention is given to scalable processes, including wet spinning, solution extrusion, thermal drawing, coating-extrusion, and automated textile integration. Finally, the review argues that the field needs standardized mechano-electrochemical testing, total-device energy metrics, reliable terminals, breathable encapsulation, and manufacturing-level quality control. These priorities shift the design target from a flexible laboratory cell to a durable energy fiber that can be processed, connected, and used as part of a real textile system.