Light-Assisted Metal-Air Batteries: Progress, Challenges, and Perspectives.

Metal-air batteries are considered one of the most promising next-generation energy storage devices owing to their ultrahigh theoretical specific energy. However, sluggish cathode kinetics (O 2 and CO 2 reduction/evolution) result in large overpotentials and low round-trip efficiencies which seriously hinder their practical applications. Utilizing light to drive slow cathode processes has increasingly becoming a promising solution to this issue. Considering the rapid development and emerging issues of this field, this Review summarizes the current understanding of light-assisted metal-air batteries in terms of configurations and mechanisms, provides general design strategies and specific examples of photocathodes, systematically discusses the influence of light on batteries, and finally identifies existing gaps and future priorities for the development of practical light-assisted metal-air batteries.