(Digital Presentation) Importance of Electrified Interfaces in Researchable Metal Anode Batteries: Ionic Liquid Electrolyte Composition and Electrode Preconditioning

Abstract

Electrode/electrolyte interface is an important part of many electrochemical systems, as its local structure, so called electric double layer (EDL), defines mechanism of charge transfer and stability of the device. Alkaline metal anodes possess high theoretical capacity due to ability of metal-ions to pack in the dense crystal structure, however, their application is rather limited due to formation of dendrites from non-uniform metal deposition and/or poor quality of the interphase. Experimentally, it was found that variation of ionic liquid (IL) electrolyte composition (salt concentration, presence of cosolvent) and applied current density for the formation cycling, i.e., cycling to activate electrode surface before utilisation, significantly affect dendritic growth and stability of metal anode. This presentation aims to show the molecular level relationships between interfacial structure, value of metal deposition potential and the interphase formation with ionic liquid electrolyte of different compositions (salt concentration, presence of cosolvent). Each electrolyte composition results in a particular interfacial metal-ion solvation environment which controls the reductive stability, metal-ion deposition potential, and ultimately the composition and properties the solid-electrolyte interphase (SEI). The latter is dependent on the EDL composition such as the IL cation/metal cation-IL anion ratio or the presence of other surface active additives. Based on this work, our group at Deakin University developed a theoretical framework to choose an optimum current density for the formation cycling of lithium/sodium metal anodes with ionic liquid electrolytes of different composition (salt concentration, presence of cosolvent). Details of these findings are published in following literature [1, 2].