Proactive Lithium Dendrite Regulation Enabled by Manipulating Separator Microstructure Using High‐Fidelity Phase‐Field Simulation

Abstract Separator microstructure manipulation is a promising and universal solution to undesirable dendrite growth in Li batteries, which can be operative at the very beginning of electrodeposition. However, the relationships between dendrite morphology, Li + distribution and separator microstructures remain unclear. The traditionally believed two‐phase system of electrode and electrolyte is also extended to three‐ or four‐phase system with separator matrix and the generally accompanied coating nanoparticles, adding extra difficulties to the rational design of separators. Here, this study proposes a quantified separator microstructure manipulation strategy by reconstructing a high‐fidelity phase‐field model for multi‐phase systems, in which the effective Li + diffusion coefficient and electric conductivity are coupled with dynamic multi‐phase evolution. Separators within the scope of experimental modification (i.e., 40–50% porosity, inner‐pore roughness of 1.5–2.7, and multi‐layer structure) are predicted effective for dendrite regulation, indicating the feasibility of the proposed strategy. It is further revealed that the uniformity of coating nanoparticles plays a more significant role in dendrite regulation than the commonly suggested uniformity of separator matrix. By filling the gap between separator microstructure, Li + distribution and Li dendrite morphology, this research paves the way for proactive lithium dendrite regulation regardless of specific battery system.