Robyn Rutgers ’24
Due to the negative effects of nonrenewable energy, scientists and environmentalists are trying to shift to cleaner energy sources, such as wind and solar power. One obstacle that engineers face in designing clean-energy solutions is the inefficiency of storing the generated energy, often resulting in large amounts of wasted energy. However, the development of advanced batteries would allow for more efficient storage of generated energy and enable control over the usage of the generated energy. To this end, researchers at Stony Brook University’s Center for Mesoscale Transport Properties are studying aqueous batteries as a cleaner alternative to lithium ion batteries. In a recent study, researchers uncovered the chemical mechanism for aqueous zinc-manganese oxide batteries through X-ray fluorescence spectroscopy.
Rechargeable aqueous zinc-manganese oxide batteries are water-based batteries that are low cost, safe to use, and utilize components that are environmentally benign and earth-abundant. To study the reaction mechanism of these aqueous batteries, researchers examined the structural and chemical makeup of the batteries with the National Synchrotron Light Source II, an extremely bright X-ray light source.
When performing X-ray absorption spectroscopy experiments, results showed that more current passed through the battery than could be explained by oxidation state changes. Researchers then completed two operando imaging experiments that are performed while the sample is operating, in this case as the battery sample charged and discharged. In the first experiment, researchers produced a map of the electrode and the electrolyte. The map showed that while the battery discharges, manganese ions move from the cathode into the electrolyte. However, when the reaction stops, so does the movement of manganese ions. In the second experiment, researchers cycled the battery, charging and discharging the cell continuously. Results showed that as the battery charged, manganese concentration in the electrolyte decreased, and as the battery discharged, manganese concentration increased. These results led researchers to understand the battery’s reaction mechanism as a manganese dissolution-deposition reaction.
Usage of aqueous batteries would provide a low-cost, safe, and non-toxic alternative to lithium ion batteries as a means for grid-scale renewable energy storage. However, further research is required to fully enable the practical application of aqueous batteries. This research provides insight into the battery’s reaction mechanism, laying the groundwork for future research examining the charge-storage mechanism and battery-system integration of aqueous batteries.
 D. Wu, et al., Quantitative temporally and spatially resolved X-ray fluorescence microprobe characterization of the manganese dissolution-deposition mechanism in aqueous zn/α-mno2 batteries. Energy & Environmental Science 13, 4322-4333 (2020). doi: /10.1039/D0EE02168G
 Image retrieved from: https://pxhere.com/en/photo/1159972 or https://envirotecmagazine.com/2021/05/25/billions-of-pounds-of-green-infrastructure-investment-jeopardised-by-gb-regulations-which-favour-eu-energy-imports/