Challenges and Opportunities for Proton Batteries: From Electrodes, Electrolytes to Full‐Cell Applications

Proton batteries have emerged as a promising solution for grid-scale energy storage benefiting their high safety and abundant raw materials. The battery chemistry based on proton-ions is intrinsically advantageous in integrating fast diffusion kinetics and high capacities, thus offering great potential to break through the energy limit of capacitors and the power limit of traditional batteries. Significant efforts have been dedicated to advancing proton batteries, leading to successive milestones in recent years. Herein, the recent progress of proton batteries is summarized and insights into the challenges in electrodes, electrolytes and future opportunities for enhancing full-cell applications are provided. The fundamentals of electrochemical proton storage and representative faradaic electrodes are discussed, delving into their current limitations in mechanism studies and electrochemical performances. Subsequently, the classification, challenges, and strategies for improving protonic electrolytes are addressed. Finally, the state-of-the-art proton full-cells are explored, and views on the rational design of proton battery devices for achieving high-performance aqueous energy storage are offered.