Thermal Gradient Effects on Active Material Loss in Prismatic Formats
Internal thermal gradients accelerate prismatic cell active material loss by driving localized current crowding, high-temperature SEI growth, and particle cracking.
Through-Plane Conductivity
Meaning
Electrical or thermal transport rates measured perpendicular to electrode sheet planes define internal resistance and heat flow across laminated cell layers. Anisotropic material structures exhibit significantly lower conductivities normal to collector foils than parallel along horizontal coating directions. Characterizing through-plane conductivity determines voltage drops across active material coatings and vertical heat transfer efficiency inside battery cells.
Conductivity values change dramatically under varying mechanical compression pressures.
Electrical Resistance
Ohmic resistance perpendicular to collector foils limits high C-rate charge and discharge capabilities. Electron transport must cross active material particle boundaries, binder networks, and conductive additive interfaces. Compaction density achieved during calendering controls inter-particle contact resistance across coating thickness.
Lower electrical resistance reduces internal heating during fast charging.
Thermal Conduction
Heat transfer normal to electrode surfaces governs internal temperature profiles in stacked prismatic cells. Polymer separators and active material coatings present high thermal resistance paths compared to metallic current collector foils. Heat generated in central cell regions must cross dozens of layer interfaces to reach outer cooling plates.
Interface contact resistance dominates total thermal resistance across electrode stacks.
Pressure Dependence
External stack compression forces increase contact area between adjacent particles and layer interfaces. Increasing mechanical pressure reduces both electrical contact resistance and thermal interface resistance. Measurement fixtures apply controlled clamping pressures to mirror pack assembly conditions.
Characterization data guides optimal pack mechanical pre-load specifications.