Meaning
Thermal phenomenon occurs when different areas of a battery cell or pack lose heat at varying rates to create internal temperature imbalances. Undergoing non-uniform heat dissipation results in localized hot spots that accelerate aging in specific regions of the cell. The effect is most pronounced in high-energy packs with limited space for cooling air or liquid flow.
This uneven cooling leads to mismatched cell aging and reduced pack life.
Aging Mechanism
Areas of the cell that remain hotter than others experience faster chemical degradation and solid electrolyte interphase growth. This localized degradation reduces the local capacity and increases the local internal resistance. Over time, this imbalance forces the cooler regions to carry more current during cycling.
This feedback loop accelerates the decline of the entire battery pack.
Cooling Design
Preventing this issue requires advanced liquid cooling plates or phase change materials that distribute cooling capacity evenly. Thermal engineers must balance the coolant flow rate and path length to minimize the temperature gradient. They use simulations to ensure that the temperature difference across the cell remains under five degrees.
This design effort is essential for high-performance applications.
Commercial Outcome
Sourcing teams must select cells and module configurations that are less susceptible to these thermal imbalances. Packs designed with uniform cooling retain their capacity longer and command higher resale values. This optimization lowers the total cost of ownership for fleet operators.
It reduces the frequency of early pack replacements.
