Opportunities and Challenges of Composites for Electric Vehicles

Opportunities and Challenges of Composites for Electric Vehicles

  Polymer materials experts at chemical consultancy ChemBizR analyze the role that current and future composite materials can play in improving the efficiency of electric vehicles and thereby enhancing their appeal to consumers.

  To mitigate the adverse effects of climate change, a key global climate action goal is to shift from gasoline vehicles to electric vehicles. The solutions above will provide some mitigation for the global greenhouse gas emissions from cars that account for almost one-third of all emissions. Sales of electric vehicles have been on the rise in recent years, with a clear response from consumers around the world. Globally, some countries have set ambitious targets to include electric vehicles in their development plans, which will make electric vehicle sales reach 32% of total global car sales by 2030.

  However, despite the emission-reduction advantages of electric vehicles, several challenging issues have so far limited the widespread adoption of electric vehicles. The first and most pervasive challenge is limited driving range and consumer concerns about prices in the current EV market. According to a 2019 survey by Alix Partners, 67% of consumers want electric vehicles to be priced on par with gasoline-powered vehicles.

  The second major challenge is limited charging infrastructure, as most existing charging stations are concentrated in selected areas. According to Alix survey, 57% of consumers are not interested in electric vehicles because they cannot be charged. Compared with an average of more than 100 cars going to the gas station to refuel every day, there are only about 10 to 20 cars going to the charging station to charge every day. Charging speed is also a big problem, and it cannot be compared with the speed of refueling fuel vehicles at present. The safety issues of traction batteries and the risk of thermal runaway are also worrying.

  Solving these challenging issues will take time, and composite materials are playing a role in several R&D advances to ensure greater vehicle efficiency through lightweighting. Developments in several categories of components are presented here, including: the vehicle's drivetrain, battery packs, electric motors, inverters, and frequency converters.

The Interaction of Weight and Efficiency

  One of the first strategies commonly considered to increase vehicle efficiency is to reduce overall system weight. The lightweighting of automobiles can be traced back to the 1900s, when aluminum made a breakthrough in the automotive industry and replaced steel in most automotive components, including the body of the car. But for electric vehicles, due to safety, technical and commercial factors, such as high-volume production, cost reduction of individual components, and the use of lightweight materials to meet performance standards, we will see that this Much of the change will take place under the hood, especially across multiple powertrain components. Additionally, a study sponsored by the Aluminum Institute showed that vehicles with lightweight structural components (fiberglass or aluminum) and low-power, low-cost batteries compared to vehicles with heavy steel components and high-power, high-priced batteries , the mileage is basically the same.

Battery pack

  The most attractive developments are battery components, or battery casings, for which composite materials are already very common. Traditional electric vehicle batteries weigh more than 400kg, of which the metal battery case reaches 100kg. To this end, some industry leaders are using composite materials to reduce the weight of this battery component. For example, Germany's BMW Motor Co., Ltd. has cooperated with SGL Carbon to use carbon fiber composite materials for its battery shell; The TRB Lightweight Structures company (hereinafter referred to as TRB) also provides lightweight solutions by improving structural design. A recent TRB development reduces the weight of the battery case from 80kg to 10kg, while also increasing strength and flame retardancy.

  While manufacturers of steel and aluminum are also promoting their lightweight designs, composite materials have an advantage in meeting flame-retardant requirements and reducing the risk of thermal runaway by facilitating fast charging. Cost has always been a major bottleneck in the application of composite materials, however, suppliers in the field of composite materials (from the production of resins to the production of structures) are increasingly integrated into the automotive supply chain, which makes us Starting to see a trend towards significant cost reductions.

Motors and Electrical Components

  Electric motors account for a significant portion of a car's weight, so weight can be optimized through proper material selection, design, and integration of electrical components. Currently, some companies such as Hofer in Germany and Hyliion in the United States are focusing on the design and development of electric axles, which are characterized by using a minimum of high-voltage cables to combine the motor with the frequency converter/inverter. Obviously, this will reduce the weight of the high voltage cables and the weight of the inverter/frequency converter housing, since the inverter/frequency converter will be mounted inside the housing of the electric axle. However, challenging issues including lack of investment and collaboration across the value chain mean that e-axle technology may not meet OEMs' demands for power and cost.

  One of the biggest concerns consumers have about fast charging is the risk of thermal runaway. To this end, some automakers are designing their battery packs with systems designed to address thermal runaway. Engineers are working on three levels of protection: protection between individual cells, protection between battery modules, and protection at the battery pack level. Adding these safeguards adds weight, reduces range, and takes up limited space. It is worth mentioning that a research and development progress of coating suppliers provides an innovative solution. The technology they have developed can prevent or delay the spread of flames at the battery and battery module levels to prevent thermal runaway accidents. occur. Yes, these finish fire retardant coatings used on composites help with fire protection, weight reduction and space savings, but the problem is that global regulations are not yet in place and it is up to OEMs and their internal risk assessment procedures to determine when thermal runaway occurs How likely is it.

Looking to the future

  From a consumer perspective, it is unlikely that demand for electric vehicles will outstrip conventional gasoline vehicles at the moment. In fact, EV uptake depends on government incentives, initiatives and investments. Furthermore, the application of composite materials in structural components is expected to be mainly targeted at premium vehicles due to high unit cost and economies of scale issues. However, composite materials have the opportunity to be used in components such as battery casings and some sub-components of electric motors. In the next 3 to 5 years, composite materials can be expected to penetrate into more application fields. For larger structural components, composites may have to wait a decade or more before the industry begins to focus on replacing high-strength steel and aluminum. Furthermore, it can be expected that more suppliers of composite components, more collaborations, and more composite components with economies of scale will emerge in the future.

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