M. Fayette, Z. Grady, W. Lim, X. Li, D. Reed
Pacific Northwest National Laboratory,
United States
Keywords: long duration storage, battery, flow-assisted, manganese
Summary:
In the past thirty years, there has been significant development in the search for alternative energy sources such as secondary battery systems. Manganese (fifth-most mined metal) has attracted much attention due to its abundance, low-cost, and recyclability. Manganese-based batteries (MnO2/Zinc) have been previously commercialized and are one of the dominant technologies in the primary battery market. However, the alkaline MnO2/Zn battery is not currently considered re-chargeable due to the formation of zinc-dendrites, passivation of Zn metal, and cathode poisoning. Additionally, the alkaline MnO2 battery is limited to 1e- compared to the 2e- process that results in high gravimetric capacity (618 mAh/g). To date, there have been attempts to access the full 2e- capacity in the alkaline system, but this comes at the expense of cathode stability and limited cycle life. In this work, we report on the development of acidic manganese-based batteries that access the full 2e- capacity of MnO2, through the electrodeposition/dissolution of MnO2. The use of flowing electrolyte enhances the reversibility of the system as well as allowing for faster charging. The MnO2 cathode is paired with two different anodes to allow for high power and high voltage systems. The resultant batteries are assessed via static cells, flow-assisted cells, and other electrochemical characterization. X-Ray Diffraction, SEM/EDS, and other analytical techniques were performed to determine the morphology of the MnO2, the crystallographic orientation as well as uniformity of the deposit. Rate performance has been assessed for 10- and 20-hour discharge protocols with CE of >85% for both rates, indicating high applicability for long-duration storage. Consequently, this work points toward a further development for flow-assisted batteries for scalable applications.