Meaning
Flow of heat across the boundary between two solid surfaces, such as a battery cell casing and a cooling plate. Optimizing interfacial thermal transfer reduces the temperature gradients within a multi-cell pack, preventing localized hot spots that can trigger thermal runaway. The thermal resistance of this junction represents a critical bottleneck in the thermal management system of high-voltage battery packs.
Contact Impedance
Microscopic air gaps between the metal surfaces act as insulators, preventing efficient heat flow. If the surfaces are not compressed together, these gaps reduce the heat transfer rate, causing the cell temperature to rise under heavy loads. Maintaining physical pressure helps close these gaps.
Material Selection
Thermally conductive pastes or gap fillers are applied between the cell and the cold plate to displace the air and establish a continuous heat path. When selecting a material, engineers evaluate both the thermal conductivity and the mechanical compliance of the gap filler. A compliant material absorbs the mechanical strain of cell swelling without losing its thermal properties or squeezing out of the joint over time.
Heat Dissipation
High thermal efficiency is necessary to maintain the cells within their optimal operating range during fast-charging events. If the interfacial thermal transfer is poor, the heat generated by internal resistance cannot escape, forcing the battery management system to throttle the charging current. This limitation increases the time required to recharge the vehicle.
