Innovative Strategies Toward Compact, Highly Stretchable, and Fully Transient Primary Batteries with Enhanced Electrical Output for Wearable Electronics

Balancing stretchability and degradability in batteries based on the primary battery principle, while maintaining robust discharging performance, poses a significant challenge for sustainable wearable technologies. Current reports adopting a layered stack structure often suffer from inadequate interlayer adhesion, leading to problems such as out‐of‐plane bending and delamination, as well as insufficient power density and energy density. In this context, a novel and straightforward methodology is introduced, employing in situ oxidation of molybdenum foil, a customized kirigami‐island‐bridge (KIB) structure, and an overall cast molding technique. This approach facilitates the integration of degradable primary batteries with enhanced power density (3.41 mW cm −2 ) and energy density (3.54 mWh cm −2 ). Furthermore, the battery sustains an output of 50 µA cm −2 under cyclic 20% strain stretching for ≈3 h, showcasing its specific stretchability performance, and is successfully implemented in sensors for real‐time monitoring of body movements. This study presents a novel approach to the development of wearable, biodegradable, and medical electronics, offering potential pathways for sustainable technological advancement.