Electrochemical-mechanical-thermal multiphysics coupled electrochemical impedance spectroscopy model for composite cathode all-solid-state lithium batteries: Quantifying the correlation among real solid-solid contact-impedance-damage under low temper

All-solid-state lithium batteries (ASSLBs) are promising next-generation energy storage technologies due to high safety and energy density, yet electrode-solid electrolyte interfacial defects hinder their practical application. Focusing on LiCoO 2 /LLZO composite cathode ASSLBs (with conductive agents and Li anodes), we constructed an electrochemical-mechanical-thermal multi-physics coupled electrochemical impedance spectroscopy (EIS) model under varied solid-solid contact states (including low temperatures). Low-temperature interfacial contact quantification clarifies the correlation between actual contact states and EIS responses, plus a law: better interfacial contact reduces damage. Full-discharge simulations show higher contact coefficients lower interfacial impedance, accelerating Li + (de)intercalation and electrochemical kinetics. DRT/ECM analysis confirms contact states negatively correlate with R c /R ct (R b stable); contact states also regulate interfacial reaction rates, verifying the contact-damage law. This work quantifies the contact-EIS correlation mechanism, enables precise contact state diagnosis for composite cathode ASSLBs, and supports interfacial optimization and stability enhancement. • A multi-physics coupled EIS model is established for composite-cathode ASSLBs. • Real solid–solid interfacial contact is quantified by the Persson contact theory. • Negative correlation among interfacial contact, impedance, and damage is identified. • DRT and ECM are used to quantitatively analyze contact-related impedance responses.