Monday, 15 March 2021

Polymeric Materials in Automotive: The Increasing Importance of Plastics for EVs and Autonomous Driving

 


In this blog post I cover six areas which deal with the increasing importance of plastics for Electric Vehicles (EVs) and autonomous driving starting from 2020.

Table 1: overview of key focus areas for plastics in EVs and autonomous driving

Let us walk through all the six areas:

Light-weighting – range extension and efficiency for electric cars

Light-weighting plays in several areas of the EV an importance and aims to provide smaller and lighter components. In a standard internal combustion engine car, plastics represent over 50% of the volume, however only 10% of the car weight.  The battery pack is the heaviest part of the whole electric car and plastics light-weighting solutions have the potential to lower the overall weight situation. Current battery housings are made using an aluminum cast solution [1]. Furthermore, battery housings need to fulfill several requirements such as crash protection, battery cooling and ease of maintenance. Thermoset based composites, as well as step by step thermoplastic composites show potential to replace aluminum castings and fulfill the afore mentioned requirements.

Amorphous materials for sensors and LEDs

LED-based lighting technology is already state of the art in cars and it offers many possibilities for the design and functionality of classic front and rear lamp applications. There are already diffractive seamless lens structures which integrate a holographic film into a polycarbonate rear-end structure. Ongoing is the integration of electronics and driving sensors such as LiDAR and radars into one operating unit. The integration of LiDAR systems into invisible components is achieved by using black-panel-based polycarbonate color technology. This solution guarantees the highest IR transmission based on the required IR laser wavelength. Polycarbonate will play a key role for so-called people mover which have large transparent structures. Realizing these structures can be done via the polycarbonate glazing technology (360° glazing concepts).

Electroactive Polymers

In a previous post I highlighted already the importance of electroactive polymers. Polyvinylidene fluoride (PVDF) has piezoelectric as well as ferroelectric properties which can be used to make car speaker systems. The integration of vibrating surfaces all over the car (dashboard; turning headrests into resonating chambers) evolves the car into an entertainment center. Piezoelectric polylactic acid is another potential material solution for such new applications.

System integration

Injection moulding allows the production of complex geometries. Furthermore, system function integration with engineering polymers (e.g. integration of damping elements for noise and vibration reduction) will further reduce costs and weight in electric cars. Metal replacement of transmission housings of electric cars are an example for integration of different materials and technologies: local reinforcement is achieved by thermoplastic composite tapes (unidirectional tapes based on PPA or PPS with carbon fiber) and overmoulded with short fiber reinforced PPA or PPS. Since transmission and power electronic housings need to have EMI shielding, placing the tapes in a 0° and 90° orientation will lead to a filtering effect and as a consequence EMI shielding can be achieved. Another integration field is the two component moulding using a hard component (PA, ASA, POM) and combining it with a soft component (thermoplastic elastomer). In particular for sealing of power electronic parts and housings in electric cars, two component solutions where a flame retardant TPE is moulded on a flame retardant PP are already existing.

Interpolymer substitution and recycling

In several areas of the internal combustion engine (ICE) car, replacement of established plastics takes place. This trend will continue in electric cars as well. Polypropylene blended with polystyrene is replacing ABS in interior decorative parts. Another example is polyketone. It is an engineering polymer which shows higher heat performance compared to polyamide 6 and 6.6. Polyketone has excellent wear resistance and impact strength, outperforming POM. Furthermore, they have a low moisture absorption (similar to PBT) and have an excellent chemical resistance, in particular toward automotive fluids, hydrocarbon solvents and salts. Commercially it is attractive to replace aliphatic polyamides, POM and PBT in the automotive market, as well as other markets. Future aim of the automotive industry is to minimize the amount of different grades and simplify the polymer chemistries in electric cars. This will accelerate recycling efforts and re-usability. Key focus area is the recycling of the battery chemistry and polymers used for making cathode and anode binders.

Battery materials

Here, different polymers play a role for developing improved lithium-ion battery systems by optimizing the binder materials for anode and cathode (PVDF basis) and to develop robust solid-state batteries. Solid-state batteries will allow the customer to recharge the battery in a short period of time and offer more mileage range too. Furthermore, metal replacement of battery housings and module parts will continue, as already highlighted in section one. Engineering polymers are more and more used as battery module separators and end plates.

How electrification influences plastics manufacturing

The next five years will show an increase of plastics demand from the automotive industry. Demand increase will be seen in certain polymer types, combined with application focus. Polyolefins such as polypropylene will grow due to expanding exterior and interior applications. Also, thermal conditions are much lower in electric cars (60-80°C) allowing polypropylene to replace engineering polymers, as well as engineering polymers replacing high heat polymers in certain areas.

Higher growth rates are expected in the Asia-Pacific regions compared to established automotive markets. Focus on innovation will allow manufacturers to meet the upcoming application requirements. Also focus will be on the establishment of a circular economy and structured recycling. 

Thank you for reading and #findoutaboutplastics

Greetings,

Herwig Juster

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Literature

[1] https://www.spotlightmetal.com/solutions-for-ev-battery-housing-at-euroguss-2020-a-900422/

[2] https://www.composites.media/the-future-of-thermoplastics/

[3] G. Pilz, et al. : Dynamic Mechanical Profile of Polyketone Compared to Conventional Technical Plastics, AIP Conference Proceedings 1779, 070008 (2016); https://doi.org/10.1063/1.4965540

[4] http://www.poketone.com/en/applications/automotive_index.do

[5] https://www.kraiburg-tpe.com/en/flame-retardant-tpe-electrical-sector

[6] https://www.solvay.com/en/article/future-of-mobility-is-light?utm_medium=social&utm_source=linkedin&utm_campaign=Stories+or+Medium&utm_content=100001741732062&linkId=100000034561877

[7] https://doi.org/10.3144/expresspolymlett.2021.25


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