Improving Battery Safety with Silicones
Potting compounds
Coatings
Composites
Development of electric vehicles is moving at an astonishing pace, with the energy density of electric batteries growing with each new product generation. That makes it all the more important to ensure a thermal barrier between the battery and the passenger compartment. WACKER silicones can deliver crucial improvements to battery safety and longevity.
The Goal: Safe, Long-Lasting EV Batteries
These key challenges are the guiding forces behind WACKER’s silicone portfolio for battery safety:
Safe operation
Silicones...
- ...support battery function under ordinary operating conditions
- ...ensure safe thermal management
Thermal runaway of a cell
Silicones...
- ...interrupt paths
- ...stop heat transfer
Thermal propagation
Silicones...
- ...limit damage
- ...prevent fire from breaking through to neighboring battery components
WACKER silicones make EV batteries safer in a number of ways:
- Operating EV batteries safely
Silicones serve as thermal interface materials that efficiently dissipate heat:
Thermally conductive gap fillers, gap pads, potting compounds, pastes, adhesives - Preventing thermal propagation
Silicones can protect neighboring components. This is achieved by coating battery components, such as individual cells or busbars, with silicone:
Cell potting, cell contact system, battery vents and busbars - Limiting thermal spread
Silicones can prevent the breakthrough of a cell fire, because silicon-resin-based composite materials can be used for defining a specific path for heat to spread. Neighboring critical components can also be protected using ceramifying silicone coatings:
Ceramifying silicone coatings for heat shields, silicone-resin-based fiber-reinforced composites for the battery housing
Potting Compounds for Battery Cells and Batteries
Our technical service personnel will be happy to assist you.
Heat-Resistant Coatings and Composite Materials
ELASTOSIL® CM 145 can be applied to a woven fabric, to mica paper or to metal using a fully automated spraying system. Shown here is a standardized gas torch test.
Test parameters:
- 1 mm thick aluminum plate
- 1.44 mm thick layer of ELASTOSIL® CM 145
- See table for temperature effects and particle shooting
| No. | Time | Front Temperature | Back Temperature |
|---|---|---|---|
| 1 | 200 s | 700 °C | 202 °C |
| 2 | 6 s | Particle shooting | |
| 3 | 100 s | 1,200 °C | 298 °C |
The ELASTOSIL® CM 145 coating is still intact after being subjected to high temperatures for five minutes. The thickness of the coating grows from 1.44 mm to nearly 6 mm. Its electrical strength rises slightly. Volume and surface resistance remain virtually unchanged.
| ELASTOSIL® CM 145 | Before Torch Test | After Torch Test |
|---|---|---|
| Thickness [mm] | 1.44 | 5.92 |
| Electrical strength [kV] | 18.1 | 10.1 |
| Volume resistance [Ohm] | 7.65E/+11 | 6.12E/+13 |
| Surface resistance [Ohm] | 5.28E/+13 | 5.19E/+10 |
ELASTOSIL® CM 145 is an innovative silicone coating for use in battery housings.
This product can provide significant protection for vehicle occupants in the event of thermal runaway.
Properties of ELASTOSIL® 531 and ELASTOSIL® LR 3011:
- Better flexibility at -40 °C than with thermoplastics (PA), pliable
- Excellent dielectric isolation
- Heat-resistant (240 h / 205 °C, 3,000 h / 180 °C)
- Notched bar impact test: no damage to coating and/or no cracking
- Flame-retardant: ceramifies in response to thermal runaway, forming a stable ceramic that prevents short circuits from arising.
Other high-performance silicones for batteries
WACKER offers a wide range of specialty silicones for the following applications:
- Seals (weather packs, housing seals, etc.)
- Valves
- Battery coolant connection
- High-voltage cables
- Thermally conductive silicone components
- Silicones for sealing applications
Properties of composite materials made with high-performance resins:
- Low fire load (high SiO2 content)
- Excellent thermal and fire resistance, up to 7 h at 1500 °C for 2 mm composites
- Ceramic formation in a fire
- Negligible smoke development, no toxic emissions
- Superior thermal insulation
- Thin and suitable for molding in three dimensions
- Suitable for lightweight designs
- Passes established industry tests, e.g., UL 94, UL 2596
How Can We Help Move Your Project Forward?
Christoph Popp, Global Segment Manager E-Mobility
We are a leading silicone manufacturer with four excellence centers focused on e-mobility issues. Our global teams support OEMs and first-tier suppliers, from the initial concept to series production.
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