Li-ion battery thermal management
Keeping lithium-ion cells in their temperature window during fast charge and discharge, by boiling a dielectric fluid on the cell and by cooling the cell from the inside.
The problem
Lithium-ion cells perform best and last longest between about 15 and 40 °C, with only a few degrees of temperature difference across the cell. Fast charging and discharging generate heat faster than conventional cooling can remove it, because air, cold plates and phase-change materials all act on the outside of the cell, through the can and through an interface.
Two-phase immersion cooling
In immersion cooling the cell sits directly in a dielectric fluid. If the fluid boils at a temperature inside the battery’s operating window, boiling holds the cell surface near that temperature, with no thermal interface in between.
We built an experimental setup to study this: a sealed chamber with a condenser, a battery cycler, and temperature and pressure instrumentation. We use it to test single cylindrical cells and small packs under charge and discharge, comparing immersion with air cooling and studying effects such as partial immersion, confinement between cells and pressure regulation.
Internal cooling of cells
The second direction is to remove heat from inside the cell. The published part of this work is the Applied Thermal Engineering (2025) paper on internal flow cooling of cylindrical cells, on which I am a co-author. We are now extending the idea to large prismatic cells, of the kind used in electric vehicles, through electro-thermal modeling of cooling channels placed inside the cell.
Status
Ongoing. Experiments on immersion cooling and modeling of internally cooled prismatic cells are in progress.