Photo-Assisted Liquid Organic Cathode with Ultralow Resistance and High Diffusion Coefficient for Membrane-Free Aqueous Zinc-Ion Battery

Abstract

Photo-assisted battery electrodes typically rely on solid-state metal-ion systems, which face challenges such as low wettability and poor electrode kinetics, limiting their performance. This work introduces a significant breakthrough in photo-assisted liquid battery technology by developing an organic liquid cathode based on azobenzene compounds dissolved in high-polarity ether solvents. The bifunctional electrode integrates photoelectric conversion and energy storage capabilities, enabling efficient electron transfer under light illumination. Experimental results demonstrate that the liquid electrode exhibits a 62.6% higher discharge capacity under light compared to dark conditions. Additionally, the charge transfer resistance is reduced to 0.14% of that in solid-state counterparts, while the diffusion coefficient increases by 18.62 times under dark conditions. Upon illumination, the resistance is further reduced, and the diffusion coefficient is significantly enhanced, accompanied by a notable increase in pseudocapacitive contributions. These enhancements highlight the exceptional photo-enhanced performance of the liquid electrode. By overcoming the limitations of traditional solid-state systems, this innovation paves the way for next-generation energy storage solutions with superior efficiency and multifunctionality, offering promising applications in advanced energy technologies.