Roadmap for electrode-free aqueous batteries

Aqueous batteries are evolving as a sustainable and safe alternative to modern Li-ion batteries for large-scale and wearable applications. While significant advancements in aqueous batteries have been made in terms of electrode materials and electrolytes, the battery architecture and charge storage mechanism have remained mainly insertion/exertion or conversion-controlled. In this Perspective, we explore a new emerging concept of electrode-free aqueous batteries, where there is no need for pre-fabricated electrodes and the electrodes are deposited and dissolved directly from current collectors. A transient and dynamic solid–electrolyte interface is formed during every cycle of charging/discharging. This Perspective briefly examines the recent advancements, design concept, underlying charge storage mechanism, fundamental dynamics of the electrolytes, and the transient interface of electrode-free aqueous batteries. Finally, we identify the current challenges and future direction of this emerging field, focusing on the development of next-generation minimalist, sustainable batteries.