Effect of long range interactions on the reduction of divalent ions in N,O-chelating solvents

Abstract

Local processes inside the ion solvation shell are believed to be the main factor affecting ion reduction in battery electrolytes. Much less attention is devoted to the interaction between the ion and molecules outside the shell. We demonstrate that in recently developed divalent batteries, long range ion/solvent and ion/electrode interactions significantly affect the reduction of ions. This effect is caused by the combination of low permittivity solvents, compact solvation shells, and high charge of Mg ions (compared with Li), leading to an effect of up to 1 eV. We establish a connection between our findings and recent experiments, highlighting the potential impact of this effect on battery performance. Additionally, we warn against arbitrarily choosing the dielectric permittivity in cluster-continuum models used for simulations, as even minor uncertainties may lead to significant variations in simulation results for divalent ions.