Stability of Aprotic Electrolytes in Sodium-Air Batteries

Non-aqueous rechargeable metal-air batteries are very attractive for energy storage due to their high theoretical specific energies compared to state-of-the art Li-ion batteries. While Li-O 2 batteries are often seen as the primary alternative, Na-O 2 cells offer advantages over their lithium counterparts due to more reversible chemistry. Since the (electro)chemistry of this system is still in its infancy, one aspect we address is the stability of the aprotic electrolytes due to the high oxidation and reduction potentials in the operating environment. There is intrinsic disparity in understanding the interfaces at atomic/molecular level in organic-based solvents. This is partly due to the previously used poorly defined, polycrystalline, and/or high-surface area electrode materials in organic electrolytes containing trace levels of impurities. By employing electrochemical and in situ surface characterization methods on well-defined metal single crystal surfaces, we establish the stability range and reveal the decomposition products. Additionally, we demonstrate the impact of impurities on interfacial properties in organic environments, adding another piece to the overall understanding of selected aprotic electrolyte stability. We believe that this fundamental insight provides a pathway for the rational design of stable organic electrolytes, which are essential for the development of high-capacity sodium-air batteries. ___________________ The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan. http://energy.gov/downloads/doe-public-access-plan