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.
Transient Swelling
Meaning
Temporary volume changes in battery electrodes that occur during the active phases of charging and discharging subside once the cell reaches electrochemical equilibrium. Unlike permanent thickness increases, transient swelling represents a dynamic response to the rapid influx of lithium ions. This behavior is highly dependent on the charge rate and cell temperature.
Dynamic Expansion
High concentration gradients of lithium at the electrode surface cause localized volume expansion during the initial phases of fast charging. As these ions diffuse further into the host material, the concentration profile flattens and the transient swelling decreases. This dynamic expansion requires flexible packaging materials to prevent mechanical damage.
Pressure Spike
When cells are held under rigid mechanical constraints, the dynamic expansion creates a rapid rise in internal pressure. This pressure spike from transient swelling can temporarily strain the cell housing and compress the separator. If the peak pressure exceeds safe design limits, it can restrict electrolyte flow and degrade cell performance.
Designing containment systems requires accounting for these short-term mechanical forces.
Material Recovery
Relaxation of the mechanical stress occurs as the lithium distribution stabilizes during periods of open circuit rest. Once the concentration gradients dissipate, the transient swelling recedes and the cell returns to its baseline dimensions. This recovery distinguishes the process from the irreversible swelling caused by degradation.