Silicone 'key to growth' in regulation-driven EV markets

London - Electric vehicles (EVs) use four times more silicone than a combustion engine vehicle and continue to present huge potential growth opportunities for suppliers of these high-end materials.

That’s according to Wacker’s director global segment management industrial solutions Julia Henn, delivering an online presentation titled ‘Silicones – the key to e-mobility’.

While acknowledging trends to make parts smaller and to reduce the number and the amount of [materials] used, Henn said: “We believe this [market] will grow strongly, which is a positive trend for us.”

For example, she pointed to the area of battery safety, where “solutions have not been finalised yet” as well as trends to make cars more connected and autonomous.

But more significant is the fundamental worldwide shift to e-mobility, which Henn described as “a mega trend in society and a game-changer” for the automotive industry and its suppliers.

The global market for EVs is “very dynamic with the supply- chain realigning at the moment,” according to the presenter.

But, she added, the current steady pace of growth will accelerate significantly from 2030, as the market moves from intermediate-stage plug-in hybrids to full-scale adoption of battery electric cars.

Further developments will really depend on factors such as regulation, consumer behaviour and technology developments – all of which can vary significantly by region.

China, which is the largest and highest growth market, has been strictly regulated and subsidised up to now, according to the Wacker expert.

This situation, said Henn, has led “major domestic OEM car makers – the so-called new force – to develop very economic solutions and battery platforms.” For instance, she cited the Wuling Hongguang mini EV, which has been sold at a remarkably low price of Euro4,000.

While Europe, the second largest market, has seen less regulation, governments and carmakers there have set very clear strategies for the development of e-mobility. For instance, noted Henn, Volvo has announced targets to be fully electric by 2030.

In the US, meanwhile, e-mobility has not been such a big topic until now due “to [driving] range anxiety and relatively low cost of fossil fuels.”

Henn, however, forecast a significant shift towards e-mobility in the US, driven by clean energy legislation introduced by the Biden administration last year.

This, she stated, should “really trigger automotive OEMs and their suppliers to establish production [for EVs] in the US.

While in Asia, overall EV sales are relatively low to date, there “are certain government incentives like in India for instance are designed to speed up both adoption and manufacture of hybrid and electric vehicles.”

In some Asian countries, Henn added, “strategy focuses more on markets in foreign countries, though it is important to remember that Asia is the main battery source for the global e-mobility market.”

Henn went on to explain that silicone rubber and related polymers are widely used in EV applications due to the strong and highly flexible silicon-oxygen bond in the backbone chains. This chemical make-up means the polymers are chemically inert and resistant to heat and oxidation.

Other specific advantages, she noted, can stem from the addition of inorganic fillers, such as aluminum oxide or aluminum hydroxide, which make the silicone rubber thermally conductive.

As well as the battery, which is the largest EV application for silicones, there are also significant uses in the engine area and in electronics displays and sensors.

Examples, here, include the use of silicone rubbers to bond cover glass to displays to avoid reflections and make the units longer lasting. And with EVs being fitted with more and larger displays demand here will grow significantly.

Fuel cells will remain part of future mobility concepts especially for trucks, and Wacker has been selling sealing materials for the bipolar plates, continued Henn.

Another important application is high voltage cabling, where for instance, silicone materials are optimised for ease-of-assembly and “to make sure that the electrical insulation is delivered”.

Henn’s presentation also focused on battery applications, where silicone gap fillers and thermal interface materials are used to couple the battery modules to the cooling plate.

A key requirement in this application area is to dissipate the heat and ensure that the battery remains at an optimum temperature range of between 20°C and 40°C.

Wacker, she said, provides products with thermal conductivity between 2W/mK and 5W/mK, as well as optimised flow and processing characteristics to significantly reduce cycle times. Products can also remain soft and tacky from -50°C to +180°C.

Indeed, Henn said Wacker’s projects with the automotive OEMs for battery gap fillers have “really been a trigger for us to sell directly into the automotive industry.”

Heat management is important also in the encapsulation of power electronics such as onboard chargers or inverters. The key requirement here is to dissipate the heat effectively with thermally conductive products at the same time as ensuring encapsulation.

“So, the challenge is to have a low viscous, yet sedimentation stable, highly-filled material,” the silicones manager explained.

Wacker, she said, has developed a range of products with a thermal conductivity between 0.8 W/mK and 4.0W/mK.

With regard to the critical topic of battery safety, Henn said battery manufacturers and automotive OEMs are really developing various concepts to ensure passenger safety in the event of thermal-runaway.

Wacker provides several solutions to be placed at different parts of the battery, including a specially developed coating, which when exposed to heat it completely ceramifies, offering temperature resistance to over 1,000°C.

In summary, Henn concluded that the EV share of car sales will increase significantly from 2030 onwards, with the market set to realign and move towards more localised production.

Silicone elastomers and related materials, she concluded, have a major role to play in these developments due to their properties that make EVs more reliable, longer-lasting and more efficient.