Abstract
Practical Mg batteries require electrolytes that are stable both toward reduction by Mg metal and oxidation by high voltage cathodes. State-of-the-art Mg electrolytes based on weakly coordinating Mg salts utilize standard ether-type solvents (usually glymes) due to their reductive stability. However, the oxidative stabilities of these solvents are less than ideal, leading to difficulties in realizing the high oxidative stabilities of recently developed salts. On the other hand, alternative solvents with greater oxidative stability are typically unable to support Mg cycling. In this work, we report a selective solvation approach involving the combination of glyme and hydrofluoroether solvents. Selective solvation of Mg2+ by the glyme solvent component increases the oxidative stability of the glyme while maintaining sufficient reductive stability of the non-coordinating hydrofluoroether. We show that this approach enables the design of electrolytes with greater oxidative stability than glyme-only electrolytes while retaining enough reductive stability to cycle Mg metal. We also relate the influence of various coordination interactions among the solvents and anions with Mg2+ to their electrochemical stabilities to better inform the design of future electrolytes.
| Original language | English |
|---|---|
| Pages (from-to) | 3264-3277 |
| Number of pages | 14 |
| Journal | ACS Applied Energy Materials |
| Volume | 6 |
| Issue number | 6 |
| DOIs | |
| State | Published - Mar 27 2023 |
Funding
This work was led and supported by the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. The authors acknowledge the computing resources provided on Bebop, a high-performance computing cluster operated by the Laboratory Computing Resource Center at Argonne National Laboratory. The NMR measurements were performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). The authors thank John Vaughey (Argonne National Laboratory) for providing the cast MgCr2O4/Mo cathode material). The authors thank Stephen Meserole (Sandia) for assistance with Raman measurements and James Ohlhausen (Sandia) for assistance with ToF-SIMS measurements. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government. This work was led and supported by the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. The authors acknowledge the computing resources provided on Bebop, a high-performance computing cluster operated by the Laboratory Computing Resource Center at Argonne National Laboratory. The NMR measurements were performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). The authors thank John Vaughey (Argonne National Laboratory) for providing the cast MgCrO/Mo cathode material). The authors thank Stephen Meserole (Sandia) for assistance with Raman measurements and James Ohlhausen (Sandia) for assistance with ToF-SIMS measurements. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government. 2 4
Keywords
- coordination
- electrochemistry
- energy storage
- magnesium
- solvation
- spectroscopy