Analysis of the application prospect of composite materials in the field of new energy battery shell

High-performance plastic solutions for battery casings

The automotive industry is in the midst of dramatic change around the world.

Alternative drive technologies, new connectivity modes and autonomous driving all require entirely new car design concepts.

One of Covestro's current focuses is the use of polycarbonate plastics in electric vehicles.

At the heart of future electric and hybrid vehicles are lithium-ion batteries. In order to accurately place a large number of cells in a small space, the battery holder and battery holder, as well as the housing assembly, must have very strong dimensional stability and a high degree of mechanical robustness.

According to the design principle of the battery pack, the material must also be flame retardant, in addition, even at wall thickness as low as 0.75 mm, to comply with the United States Underwriters Laboratories Inc. (UL94 combustible grade V-0.

High-performance plastic solutions for battery casings are as follows: Covestro has many years of experience in encapsulated lithium-ion batteries for laptops and other electronic devices.

To achieve this, the company has developed a variety of polycarbonate mixtures that not only meet the above requirements, but are also extremely impact-resistant over a wide range of temperatures, especially at sub-zero temperatures.

"The properties of the materials used around the battery play a decisive role in many functional and safety tests for finished components and contribute to the safe operation of the battery throughout its life cycle," the EV expert added.

Custom materials: Bayblend?FR type flame-retardant polycarbonate ABS (acrylonitrile-butadiene-styrene) mixture is ideal for battery holders and modules.

The material has heat resistance and dimensional stability, and it can be used for the efficient production of parts by injection molding process.

The material is also used in mobile rechargeable batteries from Berlin-based manufacturer GreenPack. The collision absorber that will be on display at Fakuma 2018 is made from PC-PBT (polybutylene terephthalate) Makroblend?KU-27912/4.

The material has very high impact strength and particularly high ductility at low temperatures.

The honeycomb structure makes the collision absorber highly resistant to impact.

Another special material, high-fill polycarbonate material from the Makrolon?TC product range, has been applied to heat sinks for LED lamps.

These products are thermally conductive but are also used as electrical insulation products, so they contribute to efficient battery thermal management.

Battery packs for harsh environments: Enduros models must be prepared for high winds and various weather conditions, but above all must withstand the most demanding mechanical performance requirements.

Among these off-road models, the trend is also electric.

California e-bike specialists AltaMotors are the leading manufacturer of such devices.

Batteries under the brand name Alta Pack are equipped with a sheath made from Makroblend?, a PC-PBT blend that is extremely impact-resistant.

Analysis of the application prospect of composite materials in the field of new energy battery shell

It is expected that the application prospects of composite materials in the field of new energy battery shells are still very promising, and we know that battery shells are pure incremental parts in new energy vehicles, and the value of bicycles is about 3,000 yuan.

The battery shell is mainly composed of the upper cover and the lower shell, which is the "skeleton" of the power battery module, which is used to protect the battery PACK against external impact, dust and waterproof.

The battery package housing (also known as the battery slot, box, or housing) of an electric vehicle is mainly used to pack and protect the battery. They come in all shapes and sizes and, as with other automotive parts, there is a wide choice of materials and fierce competition among them.

Battery case brings electric vehicle problems: The range anxiety of electric vehicles is as follows!

Mileage anxiety has always been a headache for new energy vehicles, and no matter which new car is listed, the limit mileage challenge is its must overcome the difficulties.

Reducing weight is one of the ways to improve range.

It is generally believed that if the weight of pure electric vehicles is reduced by 10%, the range can be increased by about 6%.

The "three electric" system of new energy vehicles accounts for about 1/4 of the total vehicle quality, and data show that the quality of new energy vehicles designed on the basis of traditional cars will increase by more than 15% than that of traditional fuel vehicles, so lightweight is a topic that new energy vehicles need more than traditional cars.

In the power battery system, the battery shell accounts for about 20-30% of the total weight of the system, and is the main structural part, which significantly affects its power consumption, power, braking performance, passive safety, and single-charge mileage, etc., so the lightweight of the battery shell of new energy vehicles is more important.

Lightweight is inseparable from the application of lightweight materials such as high-strength steel, magnesium aluminum alloy, high-performance plastics and carbon fiber composite materials.

To know: the characteristics and advantages of carbon fiber battery housing will shine in the field of electric vehicle applications, because carbon fiber battery housing can improve thermal insulation, reduce noise, reduce vibration, and reduce sound roughness.

◆ Reduce weight:

If the battery case is made of 100% composite material instead of aluminum, the body weight can be reduced by up to 40%.

Due to the reduced weight of the vehicle body due to the battery box factor, both the battery and engine size required are reduced when towing lighter vehicles. This positive spiral effect can reduce vehicle costs and range anxiety, helping to significantly promote the mass adoption of electric vehicles.

◆ Heat insulation:

In addition to the lightweight nature of the composite material, it also avoids the need for a separate insulation system, which further reduces the weight of the vehicle body and helps streamline the supply and value chain.

For the metal battery package housing, it is necessary to install a thermal insulation system around the material to maintain the operating temperature of the battery.

Due to the thermal insulation properties of the composite material, it is very effective in preventing heat transfer, so there is no need to install more weight gain components in the system.

◆ Noise, vibration and sound roughness:

The noise, vibration and acoustic roughness (NVH) of composites is smaller than that of metal materials because of their inherent damping properties.

This is true for battery packs and other vehicle components, where differences can mean one is more luxurious and comfortable while the other is less so in terms of driving experience.

◆ Security:

From a larger body, the composite battery housing can be designed as part of the body structure to protect not only the battery, but also the passengers in the vehicle.

The strength and stiffness properties of composites exceed those of aluminum or steel, providing better crash safety.

This combination will require close cooperation between battery package housing suppliers and chassis designers, but it is feasible to improve vehicle safety.

Recently launched composite battery solutions are as follows:

Looking back to 2021, Teijin Group's Continental Structural Plastics (CSP) has introduced several new advanced composite formulations that meet the most stringent performance standards for electric vehicle battery housing in terms of flammability, thermal runaway and VOC emissions, while offering the design flexibility of sheet moulding plastics (SMC).

These new composites include low VOC formulations, ATH filling systems, expansion systems and phenolic systems.

Furthermore, in May 2021, carbon fiber manufacturer Toray Industries (Tokyo, Japan) announced the development of a high thermal conductivity technology to improve the heat dissipation performance of carbon fiber reinforced plastics (CFRP) to that of metals.

Applying this technique to CFRP can effectively dissipate heat from its source through heat conduction paths inside the material. This helps curb battery degradation in mobile applications while improving performance in electronic device applications.

In October 2021, Fraunhofer LBF announced the development of a low-cost lightweight battery case for battery electric vehicles, which can reduce the mass by 40% compared to the aluminum battery case.

Although the component uses fiber-reinforced composite materials, its cost is lower due to the use of a specially developed efficient production process along with a stress-equivalent structural design.

The team of Fraunhofer LBF researchers, using their expertise in the field, produced a lightweight battery case with a three-dimensional sandwich design using continuous fiber-reinforced thermoplastics and an innovative process combining high-efficiency foam injection molding with CFRTP.

Evonik Industries Group (Essen, Germany) also reported last year that it is leading a consortium of partners that has developed a lighter and more economical high-voltage battery housing concept for electric vehicle solutions using fiberglass reinforced epoxy sheet molding plastics (SMC).

The overall battery system concept is designed to provide the automotive industry with a safer and more energy efficient alternative to metals or pricier carbon fiber reinforced plastics (CFRP).CFRTP

According to the understanding, the battery housing made of SGL carbon fiber composite material can reduce the weight of 50% compared to the responsive steel housing, and its performance in fire resistance, rigidity, acoustics, and thermal shielding and electromagnetic shielding can meet the corresponding requirements of the automobile.

With the help of carbon fiber composite materials, sensors can be integrated to detect damage on the underside of electric vehicles.

Future development trend and prospect analysis

Lightweight is a major trend in the current and future automotive industry, including battery casings will remain promising around 2025, and lightweight materials will replace more bulky materials in the past is an inevitable development trend.

According to foreign media reports, at present, some companies are competing to develop related commercial solutions.

For example, German specialty chemicals company Lanxess and auto parts supplier Kautex Textron are conducting feasibility studies on direct long-fiber thermoplastics (D-LFT) and polyamide 6 (PA6) resins.

Meanwhile, the Spanish Institute of Plastics Technology (Aimplas) is developing sustainably structured battery casings for light vehicles using reusable, recyclable long-fibre thermoplastic composites that enable hot-swappable battery packs after discharge.

In other developments, the Vestaro alliance takes a novel approach to the use of lightweight sheet moulded compounds for high-voltage battery module housings.

Wish the industry a more brilliant future, wait and see.

Material lightweight is the main way of automotive lightweight technology at present. From the practical application point of view, high-strength composite material is the ideal material for automotive material lightweight.

The lightweight of car body is consistent with the development direction of material lightweight. The traditional body is dominated by steel, accounting for 30% to 40% of the mass of the car. If some parts are replaced with magnesium aluminum alloy, or even high-strength composite materials such as carbon fiber, the weight reduction effect of the car will be more impressive. Major automobile manufacturers have taken vehicle lightweight as a key research goal, which has promoted the rapid development of composite materials.

In the future, the development of polymer composites will face the following challenges:

In terms of environmental protection, it is necessary to speed up the research on the recycling technology of composite materials, improve the reuse rate of composite materials, reduce environmental pollution, and realize the sustainable development of resources;

In terms of performance, in order to make up for the lack of performance of single reinforcement composites, the direction of multi-scale reinforcement composites can be expanded to make the application of composite materials in automobiles more diversified.

In terms of overall development, the development of composite materials requires the integrated and coordinated development of the entire automotive industry chain, including materials, processing technology, mold, design, equipment, testing, etc., to form a technological innovation system of industry-university-research cooperation, and there is a lot of room for technological improvement and development.

Source: SENIA, Smart Energy Expo, Central Europe

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