Mechanical Seed Mechanism to Facilitate Homogeneous Li Metal Growth

Abstract

AbstractAn intriguing mechanical seed (MS) concept that modulates (in)homogeneous Li metal growth is proposed based on an in‐depth understanding of its fundamental mechanism using unified atomistic computations. A large dataset of thermodynamic energies for Li disordered phase decouples the dual‐body interactions into three components: i) crystal‐like, ii) long, and iii) short bonds of Li─Li based on machine learning assisted by density function theory calculations. The contributions of these dual‐body interactions offer a mechanical factor for controlling the disordered‐ordered phase transition during electrochemical deposition. Macroscopic molecular dynamics simulations systematically construct the core–shell sphere and cross‐sectional models to reinforce the MS premise. The former reveals that the lower energy level of disordered phase under the moderate compression causes a slow phase kinetics, whereas the strain‐free mode exhibits a relatively fast transition. In addition, the cross‐sectional model exhibits a smooth surface landscape for the strain‐optimized case. These observations are attributed to the surface area evolutions depending on the MS conditions and elucidate the dynamic atomic displacements near the grain boundary from a local structural perspective. The proposed mechanical design concept facilitates uniform Li growth and is expected to be a global parameter in harnessing the full potential of Li metal batteries.