Meaning
Rate of energy transfer per unit area across a defined surface within or around a battery system. Measurement of spatial heat flux identifies how much thermal energy is leaving a cell and which directions the heat travels. This quantity is measured in watts per square meter and is a vector that points from hot to cold regions.
Gradient Mapping
Variations in this value across the surface of a pouch cell reveal internal manufacturing defects or localized shunts. A high spatial heat flux at a specific terminal indicates a poor electrical connection or an area of elevated internal resistance. Monitoring these patterns during cycle testing helps predict which cells are most likely to fail prematurely.
Cooling Design
Sizing of heat sinks and cold plates depends on the maximum expected values of this parameter during fast charging. Designers use spatial heat flux data to ensure that the thermal management system can remove heat fast enough to prevent thermal runaway. Properly distributed cooling prevents the formation of large temperature differences that cause uneven aging between cells.
These measurements guide the placement of thermal interface materials to maximize the conduction path from the cell core to the external cooling loop.
Sensor Integration
Placement of thin film sensors or heat flux plates between cells allows for the capture of these values in real time. The precision of the spatial heat flux measurement determines the reliability of the battery management system’s thermal safety limits. Data from these sensors also informs the calibration of lower order thermal models used in the vehicle controller.
