How cork can protect electric vehicle batteries

Portuguese company Amorim Cork Composites offers new cork solutions to protect electric vehicle batteries. The unique properties of cork, such as low density, reduced thermal conductivity and resistance to high temperatures, make it an ideal material for developing EV battery components. Additionally, cork’s cushioning and sealing properties make it suitable for a variety of applications both inside and outside the battery.

Amorim Cork Composites has used its expertise in developing high-performance materials for sectors such as seals and aerospace to create a range of solutions specifically for the electric mobility sector. These solutions focus on seals, housings and cell spacers to prevent thermal runaway during thermal events.

A solution combining cork with silicone has been developed for battery sealing. This solution meets UL-94 V0 flammability requirements and has a compression set of less than 40% at 50% deflection. It also provides resistance to wear, UV radiation and ozone. By combining cork, a 100% natural, reusable and recyclable material, with other materials, Amorim Cork Composites creates products that provide excellent performance while being environmentally friendly.

For the interior of the batteries, multi-layer systems have been developed using cork combined with materials such as mica, basalt/carbon fibers and others. These systems act as thermal barriers between cells or modules (cell spacers/thermal pads) and provide protection to the battery casing.

It may seem unlikely that you will find a material with multiple applications in cutting-edge electric vehicle drive systems that literally grows on trees, but that is exactly what Amorim Cork Composites offers.

The multi-layer systems are available in thicknesses from 0.8 to 30mm and in a wide range of formats, allowing the creation of products with a compressibility of up to 80% at 2.5Mpa, thermal insulation of 20-30°C/min and density of 200kg/m3, while guaranteeing a long-lasting solution thanks to the high cork content.

With the new range of Amorim Cork Composites solutions, we offer technical, efficient and sustainable alternatives that help guarantee the performance and durability of batteries, without forgetting the main objective underlying the electric revolution – sustainability.

Rolls Royce chooses cork solutions for the world’s first all-electric aircraft. In the “Spirit of Innovation,” the world’s fastest all-electric aircraft, cork agglomerates were used in the insulation shell of the battery box. The cork solution was chosen because of the need to find a material for the battery housing that was not only structurally sound, but also lightweight and extremely fire-resistant.

Portuguese company Amorim Cork Composites offers cork as a versatile material for cutting-edge electric vehicle drive systems. The raw material, the bark of the cork oak (Quercus suber), is widely used in various industries, such as aerospace, defense, energy and automotive. Cork is currently used for thermal protection, vibration dampening and shock absorption in battery packs of electric vehicles. According to Thomas Peroutka, Mobility Manager at Amorim, cork was used in early cars by Gottlieb Daimler and Carl Benz for sealing. Additionally, since the beginning of space exploration, cork has been used in thermal protection of rockets and satellites. Its shock-absorbing properties were beneficial in armouring applications, while its vibration-dampening and acoustic properties were used in electrical transformers.

Cork has a beehive-like microstructure, consisting of cells in the shape of tiny, gas-filled pentagonal and hexagonal prisms. There are about 40 million cells per cubic centimeter of cork. Amorim characterizes this structure as a cluster of microballoons or micro-cushions that gently press against each other, creating a characteristic blend of elasticity and compressibility that are fundamental to its dampening and shock-absorbing properties.

Moreover, cork is impermeable to gases and liquids, resistant to high temperatures, fire and friction, while being strong and lightweight.

In terms of chemical composition, 45% consists of the complex biopolyester suberin, with smaller proportions of lignin (27%), cellulose, waxes and other polysaccharides (12%), tannins (6%) and ceroids (6%).

Initially, Amorim focused on developing thermal protection pads for battery interiors, anti-vibration pads and structural elements. In structural applications, cork is combined with carbon fibers, glass fibers and/or metals such as aluminum to create housings and covers with internal thermal insulation, noise and vibration damping, impact protection, and structural integrity.

According to Peroutka, Amorim has developed a variety of materials and solutions in different formats for different applications in the e-mobility sector. The company is currently in talks with OEMs and Tier One suppliers about innovative ways to use the material.

One of these methods involves injection molding, where the cork must first be pelletized and combined with other materials. This approach allows for a wide range of process parameters, including extrusion, lamination, thermoforming and thermoforming.

Peroutka emphasizes that cork is not only carbon neutral, but actually carbon negative. Studies suggest that for every tonne of cork produced, a cork oak forest can absorb up to 73 tonnes of CO2.

Cork trees are not cut down to harvest the cork; instead, the bark is allowed to grow back for nine years before being harvested again. Each tree can be cut down around 17 times during its life, which is on average around 200 years.

What’s more, cork oak forests are key areas for biodiversity, have a protected status, help regulate the climate, promote sustainability and contribute significantly to the planet’s ecological balance.

Peroutka mentions that the first applications of the batteries, resulting from cooperation with three European companies, will be launched later this year. “We are currently conducting final tests and if everything goes according to plan, we will start the process of scaling up pre-series production.”