Tracking the Electrochemical–Mechanical Evolution by Coupled Operando X-ray Diffraction and Strain Monitoring

The investigation of electrochemical-mechanical coupling mechanisms stands as a core fundamental research priority in lithium-ion battery science. Mechanical behavior is not merely a passive physical phenomenon but a direct manifestation of underlying electrochemical processes, most notably ion (de)intercalation and phase transformations within electrode materials. Consequently, the development of nondestructive spectrum characterization techniques capable of probing electrochemical-mechanical interactions is critical for unraveling degradation pathways and failure mechanisms in lithium-ion batteries. In this work, we present a novel integrated operando X-ray diffraction (XRD) and strain monitoring platform that simultaneously correlates electrochemical performance with mechanical stress measurements, enabling real-time tracking of electrochemical-mechanical evolution. The versatility of this operando XRD system is rigorously demonstrated through a series of operando experiments conducted on commercial pouch cells under various electrochemical conditions, including different cutoff voltages, operating temperatures, and C-rates. Analysis of the correlated data sets reveals a positive correlation between differential stress and capacity, which is intrinsically linked to the phase behavior of the electrodes. These findings offer unprecedented insights into the electrochemomechanical origins of stress generation, establishing a foundational framework for the rational design of battery systems optimized for both performance and reliability.