Photo-electrochemical enhanced mechanism enables a fast-charging and high-energy aqueous Al/MnO2 battery

Rechargeable aqueous batteries, such as metal aluminum ion batteries (AAIBs), are highly desirable for large-scale energy storage owing to their low cost, long-term stability and high safety. As a promising positive electrode material for AAIBs, manganese oxide (n-type semiconductor) presents high operating voltage, good reversibility, and high energy density, while slow kinetics and undesired soluble Mn-2 + are major issues for limiting their applications. Here, we demonstrate a highly reversible photo-electrochemical coupling system, where the induced photoelectrons enable for rapid kinetics, fast charging, and enhanced rate performance. The cell under illuminated allows MnO2 for delivering a massively promoted discharge capacity 531 mA h g (- 1) (with a specific current of 0.1 A g (- 1) ) along with a high increment of 41.3%, competitive with the record values achieved in the documented AAIBs. Additionally, the generated soluble Mn2 + in discharging process could be oxidized to Mn4 + due to exist of photochemical oxidation behavior, thus further enhancing the charge storage ability. The mechanism of the photo-electrochemical coupling system has been fully understood, which provides a design path for other energy storage systems.

Automated summary

In this study, a highly reversible photo-electrochemical coupling system has been demonstrated, which achieves rapid kinetics, fast charging, and enhanced rate performance through induced photoelectrons. It also enhances the discharge capacity and charge storage ability of manganese oxide as a positive electrode material for AAIBs.