Diffusion Limited Current Density: A Watershed in Electrodeposition of Lithium Metal Anode

Abstract

Lithium metal is considered to be a promising anode material for high-energy-density rechargeable batteries because of its high theoretical capacity and low reduction potential. Nevertheless, the practical application of Li anodes is challenged by poor cyclic performance and potential safety hazards, which are attributed to non-uniform electrodeposition of Li metal during charging. Herein, diffusion limited current density (DLCD), one of the critical fundamental parameters that govern the electrochemical reaction process, is investigated as the threshold of current density for electrodeposition of Li. The visualization of the concentration field and distribution of Faradic current density reveal how uniform electrodeposition of Li metal anodes can be obtained when the applied current density is below the DLCD of the related electrochemical system. Moreover, the electrodeposition of Li metal within broken solid electrolyte interphases preferentially occurs at the crack spots that are caused by the non-uniform electrodeposition of Li metal. This post-electrodeposition leads to more consumption of active Li when the applied current density is greater than the DLCD. Therefore, lowering the applied current density or increasing the DLCD are proposed as directions for developing advanced strategies to realize uniform electrodeposition of Li metal and stable interfaces, aiming to accelerate the practical application of state-of-the-art Li metal batteries.