Physics-informed full-field strain reconstruction in large-format lithium-ion batteries using distributed optical fiber sensing

Mechanical strain monitoring in lithium-ion batteries is essential for ensuring structural integrity and operational safety. Conventional point-based measurements, however, lack sufficient spatial resolution to capture complex deformation patterns, especially in large-format batteries. Here, we report a distributed optical fiber sensor deployed on an 81.4 Ah large-format pouch battery to provide continuous spatial strain monitoring. The resulting one-dimensional strain data are first mapped onto the two-dimensional surface via a feature-point projection method. A physics-informed reconstruction algorithm then generates the full-field strain distribution. The reconstructed strain fields exhibit mean absolute errors of 12.278, 17.759, and 22.728 με for 0.5C, 1C, and 1.5C, respectively, confirming the accuracy and reliability of the proposed method. Furthermore, thermal and intercalation-induced strains are quantitatively decoupled, which reveals the characteristic evolution patterns under various C-rates and cycling stages. This sensing-mapping-reconstruction framework provides valuable spatially distributed data for battery state evaluation and early fault diagnosis.