Stability of Lithium Metal Electrodeposition across Viscoelastic Electrolytes

Abstract

The key issue preventing the use of lithium metal anodes in high energy-density batteries is undesirable dendritic deposition at the lithium-electrolyte interface, which raises serious concerns over safety and battery life. Experimental and theoretical studies have been carried out to reveal the mechanism underlying this morphological instability and to suppress it via electrolyte engineering. We study this instability by perturbing a continuum electrodeposition model which couples ionic transport across the cell, mechanical response of the anode and separator, and Marcus reaction kinetics at the anode-electrolyte interface. The analysis is validated against known results for elastic separators, then generalized to include the viscoelastic response of polymer electrolytes and to examine the impact of relaxation time. The work bridges the regimes dominated by ionic transport and reaction kinetics and can guide experimental design of novel electrolytes and separators toward stable, safe lithium metal batteries.