[NOTE] Why Is Thermal Design for EV Battery Packs So Challenging?

2026.08.26 09:58:4

As the electric vehicle (EV) market continues its explosive growth, thermal management has emerged as a core competitive factor for automakers, directly shaping the performance and safety of battery packs. Batteries inevitably generate heat during charging and discharging, and how quickly and evenly that heat is dissipated has a direct impact on energy density, output performance, lifespan, and safety. Thermal design for EV battery packs, however, presents challenges far more complex than those found in general consumer electronics.



How Is Battery Pack Thermal Management Different From General Electronics?

Thermal design for general electronics is largely a matter of locally addressing the heat generated by a specific chip or module. An EV battery pack, by contrast, is a large-scale energy storage system made up of hundreds of cells connected in series and parallel. A temperature imbalance between cells can concentrate current on a specific cell, raising the risk of thermal runaway and leading to degraded performance and a shortened lifespan across the entire pack. During fast charging in particular, a large current flows in a short period of time and heat builds up rapidly, so failing to cool the pack immediately can turn into a safety issue.

EVs must also, unlike general electronics, be capable of outdoor operation across a wide temperature range, from tens of degrees below zero to tens of degrees above zero, and the thermal material must maintain stable performance under the continuous vibration and shock encountered while driving. Taken together, the environmental conditions demanded of an EV battery pack are considerably harsher and more complex than those of general electronics.



What Are the Key Requirements for Thermal Materials?

Thermal materials applied inside an EV battery pack must satisfy a combined set of requirements that go well beyond simple thermal conductivity.

1) Gap Filling Performance: The gap between the cell and the cooling plate must be fully filled, which calls for a material with high flexibility and compressibility.
2) Low Compression Force: Battery cells swell during charging and discharging, so a material with too strong a reaction force can damage the cell structure. A material that compresses sufficiently even under low pressure is therefore needed.
3) Electrical Insulation: Because the cooling plate is generally made of a conductive metal, the thermal material must provide electrical insulation.
4) Flame Retardancy: To help suppress the spread of flame in the event of thermal runaway, flame-retardant performance of UL94 V-0 or higher is often required.



Does the Cooling Method Affect Material Selection?

EV battery pack cooling methods generally fall into three categories: air cooling, liquid cooling, and the increasingly common direct cooling.

With air cooling, a gap-filler type material is typically used to aid heat transfer between cells, or between a cell and the housing, and a low compression force together with the flexibility to accommodate cell swelling is important.
With liquid cooling, a thermal material is generally used to fill the interface between the cooling plate and the cell; here, a material with high thermal conductivity and minimized thickness is advantageous for maximizing cooling efficiency.
Direct cooling brings the coolant into direct or very close contact with the cell to absorb heat, which can deliver high cooling efficiency without a separate interface material. Because the material may be directly exposed to the coolant in this case, chemical resistance is required, along with dielectric properties to ensure electrical safety.



How Should You Choose the Optimal Solution?
Ultimately, selecting a thermal material for EV and battery pack applications is less about optimizing for any single property and more about weighing four factors together: thermal conductivity, compression force, insulation, and flame retardancy. These factors are often in tension with one another, so priorities need to be set based on the battery module's structure and its operating environment.
3C Taeyang carries thermal materials spanning this range of properties and provides product information suited to each customer's application environment. If you have any questions about material selection or spec comparison, please feel free to contact us at any time.
For technical consultation on thermal design for EV battery packs, please feel free to contact us at any time.