Digital‐Twin‐Driven Diagnostics of Crack Propagation in a Single LiNi_0.7Mn_0.15Co_0.15O₂ Secondary Particle during Lithium Intercalation

Abstract

Crack propagation has been extensively spotlighted as a main reason for the degradation of secondary‐particle‐type active materials, including LiNixMnyCo1−x−yO2 (NMC). Numerous experimental analyses and 3D‐modeling‐based investigations have been conducted to unravel this complicated phenomenon, especially for nickel‐rich NMCs, which experience substantial crack propagation during high‐voltage, high‐temperature, or high‐depth‐of‐discharge operations. To fundamentally clarify this unavoidable degradation factor and permit its suppression, a digital‐twin‐guided electro–chemo–mechanical (ECM) model of a single few‐micrometer‐sized LiNi0.7Mn0.15Co0.15O2 (NMC711) particle is developed in this study using a 3D reconstruction technique. Because the digital twin technique replicates a real pore‐containing NMC711 secondary particle, this digital‐twin electrochemical model simulates voltage profiles even at 8C‐rate within an error of 0.48% by fitting two key parameters: diffusion coefficient and exchange current density. The digital‐twin‐based ECM model is developed based on the verified electrochemical parameters and mechanical properties such as lithium‐induced strain from axis lattice parameters and stress–strain curve measured by nanoindentation. Using this model, the electrochemical‐reaction‐induced mechanical properties including strain, stress, and strain energy density are also visualized in operando in a single NMC711 particle. Finally, the advanced operando ECM analysis allows for the diagnosis of crack formation, highlighting the effectiveness of this platform in elucidating crack formation in active materials.