Quantifying the Absolute Mechanical Baseline of Lithium Plating via First-Principles Assisted Operando Expansion Tracking

Unlocking extreme fast charging in lithium-ion batteries requires ultra-early detection of lithium plating. While macroscopic expansion tracking is a promising tool, current methods rely on empirical slopes and lack a fundamental physical boundary. This work establishes an absolute mechanical baseline for lithium plating by bridging first-principles calculations with operando tracking. We quantitatively decouple the intrinsic volumetric strain of intercalation from the massive partial molar volume surge of metallic deposition. This process yields a rigorous theoretical threshold of 1.20 × 10 –4 cm 3 /C without the need for post-mortem fitting. Experiments on a pouch-cell platform demonstrate that this bottom-up baseline acutely captures mechanical anomalies during nascent lithium nucleation. The diagnostic remains robust under overcharge, subzero temperatures, and high charging rates. Finally, we translate this physical boundary into an active feedback loop for millisecond-level current derating. This framework successfully halts dendrite growth and promotes the reintercalation of dead lithium.