Advancements in photoelectrode surface, electrolyte, and integrated configurations for solar redox flow batteries – A mini review

Abstract

Under the background of the increasing contradiction between global energy supply and demand as well as large-scale application of renewable energy, as an application of flow battery technology in solar energy storage, solar redox flow batteries (SRFBs) have demonstrated rapid development owing to their high-efficiency photoelectrochemical energy conversion and adaptable storage characteristics. Although significant progress has been made in photoelectrode surface regulation, electrolyte optimization and battery integration design, improvements in system efficiency and efforts toward engineering application still face multiple challenges. In this review, the working mechanism of SRFBs is briefly introduced, and then the mechanism of improving photocurrent density and energy conversion efficiency through multi-dimensional optimization strategies such as morphology optimization, defect doping coordination, heterojunction construction and surface modification is systematically summarized from the photoelectrode interface engineering. Meanwhile, the key role of the electrolyte and illumination synergistic optimization is discussed. Finally, the breakthroughs of SRFBs in carrier separation efficiency and mass transfer dynamics optimization are analyzed in combination with innovative structures such as the cell system structure and flow channel design. This review aims to provide theoretical references for interface engineering of SRFBs photoelectrodes, synergistic optimization of electrolyte and illumination, and cell structure design. It is pointed out that the development of non-biased high-efficiency photoelectrodes, low loss electrolyte transmission systems and full-spectral-response devices represent the core direction of future technological breakthroughs.