Advances in Safe, Flexible, and Stretchable Batteries for Wearable Applications

ABSTRACT The growing demand for wearable sensors and skin‐mounted electronics has accelerated the development of flexible and stretchable batteries that can operate safely under mechanical deformation and physiological conditions. However, achieving both high electrochemical performance and intrinsic safety in such systems remains a major challenge. Previous review articles have focused on the classification of individual battery components such as electrodes, electrolytes, and current collectors, with emphasis on improving mechanical flexibility and stretchability. Here, this review summarizes the key design safety factors when a battery development considers various materials, structural deformability, biocompatibility, and self‐protection mechanisms. This article highlights how safety can be systematically embedded in a flexible and stretchable platform and analyzes the comprehensive design relationships among material composition, structural geometry, biocompatibility, and self‐regulating protection that collectively determine electrochemical and physiological stability under multi‐modal deformation. Finally, perspectives are provided for developing intrinsically safe, human‐compatible, and sustainable energy systems toward next‐generation wearable electronics.