Multi-Electron Transfer in Zinc-Based Batteries: Unraveling Redox Mechanisms Toward Next-Generation Self-Powered Technologies

The rapid expansion of autonomous IoT networks and wearable electronics has intensified the demand for photo-rechargeable zinc-based batteries (PRZBBs). While realizing high overall energy conversion efficiency intrinsically relies on cathode materials capable of multi-electron transfer reactions, current literature largely treats the fundamental electrochemistry of aqueous zinc batteries and the macroscopic engineering of solar-integrated devices as isolated domains. This review bridges this critical gap, offering a unique positioning by establishing a unified analytical framework that directly links fundamental multi-electron redox mechanisms to the dynamic architectural requirements of PRZBBs. Moving beyond a conventional cataloging of material classes, we critically evaluate diverse cathode platforms, including transition metal oxides, Prussian blue analogues, organics, halogens, and sulfur. Our incremental contribution lies in decoupling how specific multi-step reaction kinetics, distinct voltage plateaus, and dominant charge carriers dictate solar cell coupling strategies, particularly concerning maximum power point matching and intermittent charging adaptability. Furthermore, we critically and systematically assess the practical bottlenecks of these chemistries, such as shuttle effects, kinetic limitations, and voltage hysteresis, that hinder scalable integration. Finally, we distill these insights into a prioritized, roadmap-oriented perspective, outlining the short- to long-term engineering and scientific milestones necessary to translate fundamental multi-electron zinc chemistry into next-generation, commercially viable self-powered technologies.