Novel Theories for Modeling the Surface Stabilization and Dendrite Suppression for Lithium-Metal Anode Based on Piezoelectric Effect

Abstract

During electrodeposition, a small perturbation can cause the metal surface to lose its stability and form dendrite. Lithium dendrite is a key barrier that has impeded the commercialization of lithium metal batteries as well as fast charging. We find a piezoelectric mechanism to suppress dendrites, whose effect measured by over-potential can easily be 106 stronger than mechanically blocking dendrite with a stiff film. We first expanded the classical electrochemical reaction kinetics by incorporating the effect of stress and thin film piezoelectricity. We then developed a novel theory that couples the fields of electrochemistry, piezoelectricity and thin film mechanics. We then developed a rigorous stability analysis approach to reveal the effect of surface tension, mechanical blocking and piezoelectric mechanism on the stability of electrodeposition. We finally developed a theoretical expression of the critical wavelength, which provides useful guidance on achieving stable electrodeposition for various systems [1].We further developed a theory for a bulk porous piezoelectric medium which couples electrochemistry, piezoelectricity, and mechanics. Specifically, we derived a piezoelectric overpotential, which reveals a fundamental relation to surface charge density, dielectric property of the medium, electrolyte concentration and diffusivity, and the reaction coefficient. Our simulation results show that piezoelectric medium can effectively suppresses electrodeposition on any protrusion, leading to a flat, dendrite-free surface [2].