Solvation–Reduction Coupling in Ca~(2+) Electroactivity in Glyme-Based Electrolytes: A First Principles Study

摘要

The electrochemical activity of solvated Ca~(2+) in glyme-based electrolytes isinvestigated using grand canonical density functional theory approach andFukui functions. The obtained results reveal that the length of glymemolecules has little effect on the reduction potentials, but has significantimpacts on the effective electron transfer process. In short chain glymes, thetransferred electron is located on a Ca~(2+) center and the organic part of thesolvation sphere, leading to a direct Ca~(2+) reduction and a partial degradationof the glyme molecules. As the glyme’s length increases, the reductionprocess turns into the formation of solvated electrons rather than Ca~(2+)reduction, unless a partial desolvation occurs. Consequently, an effective Ca~(2+)reduction in long chain glyme-based electrolytes is controlled by a (partial)desolvation of the solvation sphere. These results can be used as guidinginformation to design new electrolytes having the Ca~(2+) reduction potential inan accessible voltage range together with an effective Ca~(2+) reduction process.The methodology developed in this study can be universally applied toinvestigate the thermodynamic and kinetic properties of other battery systemsusing metal anodes, which might lead to a paradigm shift in the design ofprospective electrolytes for future battery technologies.