Zwitterionic Hydrogels Endow Zinc‐Ion Micro‐Batteries with Superior Durability for Electrophysiological Monitoring

Abstract Zinc‐ion batteries are attractive candidates for wearable electronics due to their inherent safety and high theoretical capacity, whereas their application remains hindered by interfacial instability and mechanical rigidity. Herein, a 3D‐printed flexible zinc‐ion micro‐battery (FZIMB) is presented employing a zwitterionic hydrogel electrolyte based on carboxymethyl cellulose modified by adenosine monophosphate (CMC‐AMP). The self‐assembly of zwitterionic adenosine monophosphate (AMP) induces biomimetic pseudo‐ionic channels within the hydrogel matrix, forming highly ordered pathways that enable efficient and rapid Zn ²⁺ migration. Simultaneously, the highly flexible CMC‐AMP electrolyte promotes in situ formation of a robust solid‐electrolyte interphase (SEI) on Zn anodes. The synergistic interaction between pseudo‐ionic channels and adaptive SEI leads to uniform Zn electrodeposition and a reversible interfacial process. Thereupon, 3D‐printed FZIMBs with the CMC‐AMP electrolyte deliver exceptional long‐term cyclability (99.3% capacity retention over 1000 cycles at 1.5 A g ⁻¹ ) and mechanical resilience (98.98% capacity retention after 100 bending cycles). When synergistically integrated with the hydrogel‐based epidermal sensors, the system enables continuous energy supply and electrophysiological signal acquisition, offering a compelling strategy for self‐sustained flexible bioelectronic platforms.