1：Experimental Design and Method Selection:

The study used a network of 37 FBG sensors for temperature monitoring. FBGs were inscribed in optical fibers using the phase mask method with a pulsed Q-switched Nd:YAG laser. Temperature sensitivity was calibrated using a Peltier device. The experimental setup included cycling the battery pack with charge and discharge protocols.

2：Sample Selection and Data Sources:

Three prismatic lithium polymer batteries (LiPBs) from Cameron Sino Technology were used, connected in series. Temperature data were collected from nine strategic locations per interface in a 3x3 matrix.

3：List of Experimental Equipment and Materials:

FBG sensors (length ~

4：0 mm), photosensitive single-mode fibers (GF1, Thorlabs Inc.), pulsed Q-switched Nd:

YAG laser (LOTIS TII LS-2137U), optical interrogator (sm125-500, Micron Optics Inc.), Peltier device, data acquisition system (USB6008, National Instruments), Turnigy Accucell-6 balance charger/discharger, power resistors (10.0 Ω and 5.0 Ω), thermal paste.

5：0 Ω and 0 Ω), thermal paste. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: FBGs were calibrated thermally. Sensors were attached to battery interfaces with thermal paste. Batteries were cycled with charge at 1.0 C and discharges at 0.7 C and 1.4 C. Temperature and voltage were monitored in real-time using LabVIEW. Data were collected during charge and discharge steps with resting periods.

6：0 C and discharges at 7 C and 4 C. Temperature and voltage were monitored in real-time using LabVIEW. Data were collected during charge and discharge steps with resting periods. Data Analysis Methods:

5. Data Analysis Methods: Wavelength shifts from FBGs were converted to temperature variations using calibration factors. Data were analyzed to create spatial and temporal thermal maps, identifying hot spots and gradients.