A theory that couples electrochemistry and thin film piezoelectricity with stability analysis for electrodeposition

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 expand the classical electrochemical reaction kinetics by incorporating the effect of stress and thin film piezoelectricity. We then develop a theory that couples the fields of electrochemistry, piezoelectricity and thin film mechanics. Such a fundamental framework is expected to help analyze various new phenomena and material innovation that involves electrochemistry and thin film piezoelectricity. A rigorous stability analysis approach is developed to reveal the effect of surface tension, mechanical blocking and piezoelectric mechanism on the stability of electrodeposition. A theoretical expression of the critical wavelength is derived, which provides useful guidance on achieving stable electrodeposition for various systems.