High‐Linear‐Energy Layered Fiber Batteries Using Roll‐to‐Roll Lamination and Laser Cutting

Abstract Fiber batteries are essential for the realization of high‐performance wearable and textile electronics with the desirable features of conventional textiles, including breathability, stretchability, and washability. However, the development of fiber batteries is limited by scalability and performance since most reported fabrication techniques are not compatible with standard battery manufacturing. This work presents a novel method for the scalable fabrication of fiber batteries with a stacked design analogous to that of conventional pouch cells using layer lamination and laser machining. To accomplish this, several poly(vinylidene fluoride‐ co ‐hexafluoropropylene) (PVDF‐HFP) separators are developed, enabling lamination between conventional battery electrodes using a heated rolling press. The laminated strips are subsequently laser cut to form fibers with widths as narrow as 650–700 µm. These prototypes are successfully cycled in pouch cells and capillary tubes, delivering very high linear energies up to 0.61 mWh cm −1 . Custom equipment is designed to demonstrate scalable fiber battery fabrication processing in a roll‐to‐roll fashion. This work marks a paradigm shift in fiber battery research by demonstrating substantial benefits over all previous approaches including optimal active material utilization, low inactive material content, scalability, and compatibility with equipment already used widely in the battery industry.