As EVs move toward 800V architectures and ultra-fast charging, battery thermal management has become more important than ever. Thermal potting compounds need to transfer heat efficiently while protecting battery modules from vibration, moisture, and electrical stress.

The challenge is that higher thermal conductivity usually means adding more ceramic fillers like aluminum oxide or boron nitride. This makes the material much thicker, so many formulations rely on low-viscosity silicone fluids to improve flow. Unfortunately, conventional silicone fluids may contain small cyclic siloxanes (D3–D10), which can evaporate during long-term high-temperature operation.

Why Low Volatility Matters

When volatile siloxanes evaporate inside a battery pack, they can cause several issues:

• Relay contamination: Silicone vapors may form insulating silica on high-voltage relay contacts, increasing contact resistance and reducing reliability.

• Lower thermal performance: Material shrinkage can create tiny voids that reduce heat transfer efficiency.

• Stress and cracking: Volume loss over time may increase mechanical stress on cells and electronic components.

Solution 1: Use Low-Volatility Silicone Fluid

The most direct solution is replacing conventional PDMS with low-volatility silicone fluid.

These materials are processed to remove low-boiling cyclic siloxanes (D3–D10), resulting in:

• Volatile content as low as 100–500 ppm

• Excellent flowability for high filler loading

• Better compliance with automotive low-emission requirements

• Stable processing without sacrificing dispensing performance

Solution 2: Add Modified Silicone Resin

For demanding applications such as battery control units or cooling plate potting, modified silicone resins can further improve performance.

Compared with standard silicone fluids, modified silicone resins provide:

• Near-zero volatile emissions

• Better thermal stability and flame resistance

• Improved filler suspension and anti-settling performance

• Higher mechanical strength after curing

A Practical Formulation Strategy

Many manufacturers combine both approaches:

• Pre-treat thermal fillers with low-volatility silicone fluid to improve wetting and reduce viscosity.

• Replace 10–30% of the silicone base with modified silicone resin to reduce volatility while improving durability.

This balance helps achieve high thermal conductivity, reliable processing, and long-term stability in automotive battery applications.

If you're looking for low-volatility silicone fluids, phenyl silicone resins, or technical support for thermal potting formulations, we'd be happy to help.

Website: www.siliconeoil.net
Email: zyf@siliconeoil.cn