Mechanical Properties and Plastic Deformation Mechanisms of Polycrystalline Lithium Metal

Lithium metal batteries have been deemed one of the most promising candidates for new-generation batteries, used in mobile devices, electric vehicles, energy storage, etc. However, due to the volume change of active materials and external pressure, the electrode materials and interfaces between battery components have high stresses during the cycling process, resulting in large deformation of the lithium metal anode. Herein, we derive insights into the mechanical behaviors of polycrystalline lithium metal. Specifically, the mechanical properties of lithium metal containing Li_7-xLa₃Zr_2-xTa_xO₁₂ (x = 0.2–0.7) (LLZTO) solid-state electrolyte impurities are experimentally investigated. It is found that its strength is governed by impurity content and impurity particle size. In addition, we explore the Hall–Petch and inverse Hall–Petch effects of nanocrystalline lithium through atomic-scale simulations, revealing the plastic deformation mechanism in polycrystalline lithium metal. This fundamental study sheds light on the impurity-modulated mechanical properties and plastic deformation mechanism of polycrystalline lithium metal.