The impact of electrode conductivity on electrolyte interfacial structuring and its implications on the Na0/+ electrochemical performance

Abstract

Molecular and ionic assemblies at electrode/liquid electrolyte interfaces, i.e., the electric double layer (EDL), define battery performance by directing the formation of stable interphases. An unstable interphase can hamper metal-cation diffusion, lead to continuous electrolyte consumption, and also promote non-uniform electrochemical processes like dendrite formation. The co-selection of electrolyte chemistry and initial cycling conditions together are generally considered for the design of desirable interphases. At the same time, the dielectric nature of the electrode material is largely ignored, notwithstanding the high unreliability of the assumption that the nature of the EDL and the mechanism of the interphase formation at metallic and semiconductive electrodes are identical. Here we show that the dielectric nature of the charged electrode greatly affects the interfacial metal–anion–solvent composition; therefore, different interphase chemistry will be formed, suggesting different initial cycling conditions need to be established on a case-by-case basis to form the desired interphase. This phenomenon correlates with the metal ion solvation chemistry and the adsorption of species at the electrified electrode due to the competition of van der Waals and coulombic interactions.