An Approach to Modifying Photoelectrodes with Nickel Foam for Enhanced Performance in Solar Redox Flow Batteries

Solar redox flow batteries (SRFBs) have attracted increasing attention as a promising technology for solar energy conversion and storage. Their performance, however, remains constrained by various factors, particularly the photoelectrode. In this study, we developed a general strategy for modifying photoelectrodes using nickel foam to significantly increase the performance of SRFBs. To demonstrate this approach, we integrated a nickel foam-modified triple-junction amorphous silicon photoelectrode with 2,6-DBEAQ/4-OH-TEMPO redox couples. The resulting SRFB device exhibited an approximate 36% increase in photocurrent density during photocharging. Over 20 charge−discharge cycles, the system achieved an average solar-to-output electricity efficiency of 5.7%, which is the highest reported value to date for SRFBs utilizing anthraquinone-based electrolytes. Electrochemical impedance spectroscopy revealed that the nickel-foam modification accelerated charge transfer at the photoelectrode/electrolyte interface. Furthermore, extending this modification approach to other SRFB systems also led to significant improvements in photocurrent density and overall performance compared to unmodified counterparts. This photoelectrode design strategy demonstrates broad applicability and is anticipated to advance SRFB technology by enhancing photoelectrode performance and overall energy conversion efficiency.