The Anion-Dominated Dynamic Coordination Field in the Electrolytes for High-Performance Lithium Metal Batteries

Abstract

Electrolyte plays a dominant role in solving the various challenges of Li-metal batteries (LMBs). The complex competition coordination and diversity of the anion coordination clusters in electrolytes are still unclear. In this paper, an anion-dominated dynamic coordination field (ADCF) theory is proposed to reasonably explain the coordination behavior in the high-concentration, localized high-concentration, and weak-ionization localized high-concentration electrolytes, which is based on specific characterizations and theoretical calculations. The novel model selects the anions as the center of the whole molecular groups/clusters, while the Li+ acts as the counterion or carrier, which can promote the dynamic and elastic movement of the whole cluster. The specific coordination clusters could remarkably enhance the interaction between TFSI- and Li+, and make the counterion composition of Li+ increase. The confinement effect of the coordination field provides a difficult ionization atmosphere for the Li+, and enables clusters to preferentially adsorb on the Li surface, and construct a specific solid electrolyte interphase (SEI). Furthermore, the electrode/electrolyte interface kinetics and the growth of lithium dendrites are systematically investigated. These new viewpoints of coordination behavior provide inclusive strategies in the electrolyte design, and promote further research of the charge transfer or solution behavior.

Keywords: anion-dominated dynamic coordination field, anion-dominated coordination clusters, electrode interfaces, Ab initio molecular dynamics, lithium batteries.