Impact of mechanical stress on electrochemical performance of the lithium-ion battery

Mechanical stress plays a critical role in the performance and degradation of lithium-ion batteries, yet their coupling with electrochemical processes remains insufficiently explored. This work investigates these interactions by fully coupling the Doyle–Fuller–Newman (DFN) model within the PyBaMM framework with a mechanical sub-model at both particle and electrode scales that accounts for both concentration-driven and interaction-driven stress contributions. The developed framework enables the consistent simulation of incremental capacity analysis (ICA), electrochemical impedance spectra (EIS), and distribution of relaxation times (DRT) under applied mechanical pressure. ICA reveals mechanical loading shifts voltage-capacity peaks, reflecting stress-induced changes in reaction equilibria. EIS complements this by showing voltage-dependent impedance evolution, with DRT spectra exhibiting changes in peak intensity and characteristic times. Using a fundamental thermodynamic framework based on Gibbs free energy minimization, we demonstrate that these shifts originate from a stress-induced modification of the chemical potential. Importantly, we show that full-cell behavior is governed by the predominant electrode, where the competition between material properties ( E p , ν , Ω ) and the open-circuit potential (OCP) slope determines the direction of voltage and impedance shifts. This framework provides a consistent physical explanation for non-monotonic impedance trends and resolves seemingly contradictory findings in previous literature, identifying the specific conditions under which mechanical stress either enhances or hinders electrochemical kinetics.