Dynamic Core Temperature Reconstruction for Transient Swelling Deconvolution in Prismatic Modules
Deconvoluting swelling requires dynamic internal thermal reconstruction to separate reversible expansion from heat driven volume growth.
Entropic Heat Coefficient
Meaning
Thermodynamic property that quantifies the reversible heat change associated with the movement of ions within an electrochemical cell describes this variable. Calculating the entropic heat coefficient involves measuring the change in open circuit voltage as the temperature of the cell is varied at a constant state of charge. The result is expressed in volts per kelvin.
Thermal Measurement
Determination of the cooling or heating effect during slow charging depends on this value. Because the entropic heat coefficient can be positive or negative, some phases of charging actually cool the cell slightly before ohmic heating dominates. This behavior is linked to the change in the disorder of the electrode lattice.
Knowing whether the reaction is endothermic or exothermic at a specific point helps in tuning the thermal control algorithm to prevent overheating during the final stages of the charge cycle.
State Of Charge
Dependency of the coefficient on the amount of lithium in the electrodes makes it a tool for state estimation. As the entropic heat coefficient fluctuates across the lithiation range, it reflects the different structural phases the active materials pass through. Precise mapping of this relationship is required for accurate thermal modeling.
Cooling Requirement
Integration of the thermodynamic data into the battery management system ensures that heat generation is accurately predicted. Using the entropic heat coefficient allows designers to optimize the size of heat exchangers and fans. In high power applications, the reversible heat component can be a significant portion of the total thermal load.