Stable aqueous aluminum-manganese photoelectrochemical cells with high-rate and high-efficiency abilities

Abstract

Aqueous aluminum-ion batteries (AAIBs) are potential candidates for large-scale energy storage devices for their advantages of high energy density, resource abundance, low cost, safety, and environmental friendliness. Due to various redox procedures, good reversibility, and high discharge potential, the aqueous aluminum-manganese oxide battery has drawn wide attention, while the critical issues induced from slow kinetics and undesired soluble Mn2+ lead to slow charging, poor rate capability, and low energy density. However, there is very limited progress for performance improvement via conventional chemical or physical modification approaches. To overcome these challenges, an efficient photo-regulation strategy has been proposed in terms of direct radiating visible light on the cell during the galvanostatic charging and discharging. The efficient separation and transmission of photoelectrons in the photo positive electrode dramatically improves the dynamics, and fast charging and enhanced rate performance could be achieved. Photo-oxidation behavior can effectively promote the conversion of soluble Mn2+, thus further enhancing the energy density of the as-assembled aluminum-manganese battery. Furthermore, a photo-conversion efficiency of up to 1.2% has been acquired. Based on the photo-regulation strategy, the mechanism of the photoelectrochemical coupling system has been understood, which opens a promising route for achieving photoelectrochemical batteries with high energy density and fast charge.