EV Battery Thermal Design: Why Insulation, Heat Removal, and Pre-Heating Must Work Together

Electric vehicle battery design is often discussed as if each thermal function is separate. One material protects against heat. Another material removes heat. Another system warms the battery in cold weather.

In reality, these functions must work together.

A modern EV battery pack is not simply a box filled with cells. It is a controlled thermal environment. Inside that environment, the battery must stay warm enough to operate efficiently in cold conditions, cool enough to avoid overheating during fast charging or high-power driving, and protected enough to reduce the risk of thermal propagation during abnormal events.

This creates an important opportunity for the insulation industry. The future is not only about selling insulation sheets, thermal pads, cooling plates, or heating films separately. The future is about designing cooperation between layers.

The battery has three thermal needs

An EV battery usually needs three types of thermal support.

First, it needs insulation and protection. This includes thermal barriers, electrical insulation, flame-resistant materials, compression pads, spacers, seals, and enclosure protection. These layers help separate critical zones, reduce unwanted heat transfer, and support passive safety.

Second, it needs heat removal. During driving, fast charging, high discharge, or heavy load conditions, battery cells generate heat. Thermal interface materials, cooling plates, heat spreaders, liquid cooling channels, graphite layers, aluminum structures, and other heat-removal solutions help move this heat away from the cells and toward the cooling system.

Third, it needs pre-heating or temperature conditioning. In cold weather, batteries may charge more slowly, deliver less power, or experience higher stress. Heating elements, heated coolant loops, thermal films, heat pumps, or controlled pre-conditioning systems can bring the battery into a better operating temperature range before charging or driving.

The challenge is that these three needs can conflict with one another.

Insulation can protect, but it can also trap heat

Insulation is valuable because it slows heat transfer. That is useful when engineers want to protect the passenger cabin, isolate a damaged cell, reduce heat loss in winter, or separate the battery from external thermal exposure.

However, if insulation is placed incorrectly, it can also trap unwanted heat inside the pack. A material that helps retain warmth during cold-weather operation may become a problem during fast charging if it blocks heat from reaching the cooling plate.

This is why battery insulation cannot be designed as a simple “more is better” solution. The correct question is not only: “How strong is the insulation?” The better question is: “Where should heat be blocked, and where should heat be guided?”

In EV battery design, insulation must be selective.

Heat-removal layers need a clear thermal pathway

Cooling materials are only effective if heat can reach them. Thermal pads, thermal interface materials, cooling plates, heat spreaders, and liquid cooling systems all depend on good contact and a controlled heat path.

If there are air gaps, uneven compression, poor material contact, or incompatible layers between the cell and the cooling system, heat removal becomes less effective. This can create uneven cell temperatures, localized hot spots, reduced performance, accelerated aging, or higher safety risk.

This is especially important during ultra-fast charging. As charging power increases, heat flux becomes more difficult to manage. The battery pack must remove heat quickly while still maintaining electrical insulation, mechanical stability, and safety separation.

This creates a technical requirement for cooperation between the insulation layer and heat-removal layer. They should not fight each other. They should divide responsibilities.

Pre-heating changes the role of insulation

Cold-weather operation makes the system even more complex.

When a vehicle pre-heats the battery, the goal is to warm the cells efficiently and evenly. If too much heat escapes into the surrounding structure, the pre-heating system wastes energy. If heat is trapped unevenly, some cells may warm faster than others. If heating elements are too close to sensitive materials, the system may create durability or safety concerns.

A good insulation layer can help pre-heating by keeping heat inside the intended battery zone. But the same insulation must still allow controlled heat removal when the battery later operates under high load.

This means the battery pack needs thermal directionality. Heat should be retained when the system is cold, spread or removed when the system is hot, and blocked when a safety event occurs.

That is a difficult design problem—and it is exactly where advanced material engineering becomes valuable.

The real design goal: thermal zoning

A future EV battery pack should be understood as a set of thermal zones.

Some zones need to transfer heat quickly. These may include cell-to-cooling plate interfaces, heat spreader areas, power electronics interfaces, and fast-charging thermal pathways.

Some zones need to resist heat transfer. These may include cell-to-cell barriers, module-to-module barriers, fire protection layers, sidewall barriers, enclosure shields, and passenger-compartment protection zones.

Some zones need to manage temperature both ways. These may include pre-heating areas, thermal buffer layers, compression pads, and multi-functional laminated structures.

This is why one single material rarely solves the full problem. A battery pack may need a combination of materials: thermal insulation, thermal interface material, flame barrier, dielectric layer, adhesive, seal, spacer, and heat spreader.

For the insulation industry, the opportunity is to become part of this zoning strategy.

Active and passive thermal management must cooperate

EV thermal management includes both active and passive systems.

Active systems include liquid cooling, pumps, valves, fans, heat pumps, coolant loops, sensors, software, and battery management systems. These systems can respond to changing conditions.

Passive systems include insulation, barriers, pads, foams, mica layers, aerogel layers, high-silica materials, fiberglass, aluminum foil, graphite heat spreaders, seals, and laminated parts. These materials are always present and do not need software or power to begin performing their function.

A strong battery design uses both.

The active system controls temperature during normal operation. The passive material system supports safety, separation, heat direction, electrical isolation, and emergency resistance. When designed correctly, passive materials also help the active system work more efficiently by reducing heat loss, improving thermal contact, or guiding heat toward the right pathway.

Why laminated and die-cut parts are important

The cooperation between insulation, cooling, and heating is not only a material-selection issue. It is also a manufacturing issue.

Battery packs contain complex geometries, narrow spaces, high-voltage components, cooling plates, sensors, adhesives, vents, fasteners, and structural parts. A material must fit precisely into the correct space. It may need holes, slots, adhesive backing, compression zones, edge protection, or multiple laminated layers.

This is where precision conversion becomes important.

A finished insulation part may combine several functions in one design:

• A thermal barrier layer to slow heat propagation

• A dielectric layer to support electrical isolation

• A foil or film layer to reflect radiant heat

• A compressible layer to maintain contact

• An adhesive layer for assembly

• A precision-cut shape to avoid blocking sensors, vents, or cooling paths

This is different from selling a roll of raw material. It is an engineered part for a specific position inside the battery system.

What this means for Lih Feng Jiing

For Lih Feng Jiing, this topic is a strong positioning opportunity.

LFJ can present itself as a partner for tailor-made insulation and protection parts that support the cooperation between cooling, heating, and safety layers in EV battery packs.

The company does not need to replace cooling plates, battery management systems, or heating technologies. Instead, LFJ can help them work better by providing precision-converted insulation and barrier components that fit around them.

Possible LFJ application areas include:

• Cell-to-cell thermal barriers

• Module-to-module insulation

• Battery cover insulation

• Battery bottom shield protection

• High-voltage dielectric insulation

• Thermal-acoustic underbody protection

• Pre-heating heat-retention layers

• Fire-resistant laminated parts

• Seals and spacers near battery enclosures

• Die-cut insulation parts around cooling plates, busbars, and sensors

This is an important message for OEMs and Tier 1 suppliers: LFJ is not only a material supplier. LFJ can be a manufacturing and development partner for finished insulation parts that support the full EV battery thermal system.

The challenge for the insulation industry

The biggest challenge is that insulation companies must now understand the neighboring layers.

In older applications, an insulation supplier could focus mainly on thermal resistance, fire rating, thickness, and cost. In EV batteries, this is no longer enough.

The supplier must understand how the insulation interacts with:

• Cooling plates

• Thermal interface materials

• Adhesives

• Heating films or pre-heating systems

• High-voltage electrical paths

• Venting systems

• Sensors and BMS data

• Structural compression

• Crash deformation

• Thermal runaway propagation

• Recycling and repair

This requires more technical communication with customers earlier in the design process. The insulation supplier must ask where heat should go, where heat should not go, how the part will be assembled, and what happens during both normal and abnormal conditions.

Conclusion: the battery pack is becoming a thermal ecosystem

The future EV battery pack is not built from isolated parts. It is a thermal ecosystem.

The insulation layer protects and separates. The heat-removal layer transfers and dissipates. The pre-heating layer prepares the battery for efficient operation. The battery management system monitors and controls. The enclosure and structure hold everything together.

The best designs will not treat these layers as competitors. They will make them cooperate.

For the insulation industry, this is a major shift. The value is moving from simple material supply toward engineered, multi-functional, precision-made components. Companies that can laminate, die-cut, customize, and support system-level integration will be better positioned for the next generation of EV battery platforms.

In electric vehicles, thermal performance is no longer only about cooling the battery. It is about controlling the movement of heat—when to keep it, when to remove it, where to block it, and how to protect the vehicle if something goes wrong.