Thermal and Mechanical Response Characteristics of a Lithium‐Ion Battery During Cycling

To clarify the rate‐dependent electro‐thermo‐mechanical response and spatially nonuniform surface stress behavior of commercial prismatic lithium‐ion batteries during cycling, this study investigates the rate‐dependent electro‐thermo‐mechanical behavior and spatial stress heterogeneity of a commercial 12 Ah prismatic lithium‐ion battery during cycling. Utilizing a multipoint monitoring platform, surface stress, temperature, and voltage were synchronously recorded under 0.5 C charge and 1/2 C discharge conditions. The results reveal that surface stress fluctuates periodically and escalates with continued cycling, with the 2 C high‐rate discharge significantly amplifying voltage polarization, stress fluctuation intensity, and thermal responses compared to the 1 C discharge. Furthermore, seven‐point surface measurements demonstrate distinct spatial heterogeneity; regions C3 and C7 act as mechanically sensitive stress concentrators, whereas region C6 exhibits stable, localized stress‐relief behavior. Thermally, while the temperature field remains relatively uniform at 1 C, the 2 C discharge doubles local temperature fluctuations (from approximately ±2 to ±4 °C at C1) primarily due to enhanced ohmic heating and heat accumulation. Ultimately, these findings underscore the necessity of using spatially resolved monitoring, rather than relying solely on global average metrics, to accurately evaluate local battery responses, providing a crucial experimental foundation for optimizing sensor layouts, designing cycling strategies, and conducting mechanical safety assessments.