Electric cars They must be safe and lightweight

25 Jan 2022

By October 1, 2021, around 1 million electric cars had been registered in Germany. Of these, according to statista.com, 517,000 cars were powered solely by electrical energy, while 494,000 were plug-in hybrids. Therefore, in order to meet the goal of 15 million fully electric cars, the development of the cars and the charging infrastructure needs to be driven forward significantly.

The research and development work to achieve this is already proceeding at top speed. But on top of the chip shortage and lack of charging stations, there are further challenges that need to be overcome. These include:

Ensuring the safety of the occupants, emergency services, and mechanics in every situation.
Meeting extremely stringent requirements concerning flame-retardant properties in case of a fire.
Improving the range through lightweight solutions.

As a specialty chemicals company, LANXESS offers a host of products and potential solutions for these challenges. Many of them even from a single source.

Greater safety under the hood
Vehicles with electric drives are naturally exposed to higher voltages and currents than combustion engines. Voltages of up to 400 V DC in the battery circuit and up to 1,000 V AC in the engine circuit are possible, with AC voltages exceeding 42 V and DC voltages exceeding 60 V already considered potentially life-threatening.

In electric cars, the live components of the electric drive are colored orange. It must be possible to identify them as dangerous. Our new colorant Macrolex Orange HT is precisely the right orange tone for this purpose. This color is increasingly being used to mark live cables in electric and hybrid vehicles as well as components for high-voltage applications. The signal color is intended to alert mechanics and emergency services to the potential danger of electric shock.

Macrolex Orange HT is highly suitable for use in polyamides, but it can also be used to color other types of plastic such as polycarbonate or polyphenylene sulfide, which often pose a challenge for colorants due to their high processing temperatures.

Dr. Lars May, Head of Application Technology Plastics in the Polymer Additives business unit, LANXESS “We have already extensively tested our new products under realistic conditions. In cooperation with our High Performance Materials business unit, we colored compounds with Macrolex Orange HT at the plastics technical center in Dormagen and tested them for their suitability in plastics processing.”

In addition to high-voltage applications, Macrolex Orange HT can also be used to color other plastic products such as housings for tools and other electronic devices as well as technical plastics for vehicle parts and structural applications.Macrolex Orange pigments for coloring plastics for high voltage applications

Secure connections in numerous colors
Cable harnesses run the length and breadth of the vehicle and bundle all the various on-board power supply lines for electric and electronic functions such as power converters, battery charging systems, electric drives, and infotainment systems. Cable harnesses are among the most complex assemblies found in electric vehicles.

The total length of the cables can reach several kilometers, which is one of the reasons why cable harnesses are so heavy. The complexity of cable harnesses makes them extremely expensive components, which is why the connectors must not break during installation.

To distinguish more easily between the many connectors during installation and maintenance, they must be marked in different colors. At the same time, they have to be flame-resistant and mechanically robust.

It is precisely for these connector applications that our product developers designed the technical plastic Durethan BKV30FN04. A polyamide 6 that has already been tried and tested in numerous series applications – including in cable harnesses for various electric models produced by a European-US automotive manufacturer. One further benefit is that the material is halogen-free.

Dr. Stefan Theiler, Application developer for plastics, Business Unit High Performance Materials, LANXESS “The compound and color exhibit a high level of heat stability, which means that the connectors can be easily and reliably distinguished by color throughout the vehicle’s entire service life.”

Durethan BKV30FN04 is used for connectors not only in the field of electromobility, but also in signal transmission technology and industrial engineering.

Lightweight solutions – For electric cars more than ever

Connector made from Durethan BKV30FN04 for cable harnesses in electric models produced by a European-US automotive manufacturer. The halogen-free flame-retardant polyamide 6 can also be dyed in bright colors like orange (RAL 2003) In a research collaboration lasting multiple years, LANXESS and Kautex Textron GmbH & Co. KG have been exploring whether high-voltage battery housings for electric vehicles can be designed and produced with technical thermoplastics. Together they have developed a close-to-production technology demonstrator in a feasibility study. Measuring around 1,400 millimeters in both length and width, this is a technically sophisticated, large-format all-plastic housing part. The weight is in the mid-double-digit kilogram range.

The aim of the project was to illustrate the advantages of thermoplastics over metals in terms of weight and cost reduction, functional integration, and electrical insulation properties.

“In the process, we did not use any metallic reinforcement structures whatsoever. It was also about highlighting ways to produce the large, complex parts economically." Felix Haas, Director Product Development bei Kautex Textron

As a next step, both partners want to use the results of the collaboration to enter into development projects for series production with car manufacturers.

Battery module housings: lightweight and flame-resistant
Depending on the cell type, the very large HV battery housing often contains several modules in which the cells are mounted. For this purpose, we have developed a battery module housing together with the Korean automotive parts manufacturer INFAC.

The battery housing is made of Durethan BKV30FN04. The technical plastic based on polyamide 6 is halogen-free, flame-retardant, and glass-fiber reinforced. The advantages:

It is particularly flame-retardant,
has excellent electrical properties,
is very easy to process, and
enables the integration of complex functions that are required for the housing parts.

All of that results in a smaller number of parts, a simplified assembly process, and reduced weight, too.
The new battery housing component is already being used in the series production of electric vehicles. One model series for a Korean car manufacturer was launched on the market in 2021.

Michael Rockel, Head of Business Unit High Performance Greater ChinaMichael Rockel, Head of High Performance Materials in the Asia-Pacific region “The success achieved with the series production of battery housings shows the outstanding performance of Durethan in relation to batteries for electric vehicles. Here, technology and safety are of prime importance. Our high-performance plastics will make a significant contribution to the market development of electric vehicles and batteries.”

In addition to thermal management, the damping for protecting the battery from external impacts is key for the battery module housing. Durethan BKV30FN04 is not only mechanically robust. It is also effective in insulating against high voltages of up to 800 V and the corresponding current if the part is designed accordingly. With its highly flame-retardant properties, it prevents or delays the spread of flames in the event of a fire.

That´s the future
If you observe the automotive industry, you quickly see that new models are constantly being unveiled. The selection is becoming wider. Not least due to the EU Commission’s call to reduce CO2 emissions to zero by 2035, the combustion engine is coming to the end of the road. Subsidies are intended to work against it while promoting sales of electric cars. Many things will change in the coming years. And LANXESS will be part of the change. We are looking forward to it.