The markets: Fuels cells and batteries (2020)
Although fuel-cell powered vehicles could still be in the automotive future, growth will be measured, and so will the market there for composite components. Composites for electric vehicle battery packs and hydrogen tanks for fuel cell vehicles will be the more immediate opportunity.
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Williams FW-EVX features CFRP battery module boxes made with the 223 fold-to-form process. Source| Williams Advanced Engineering
More than 80 concept, demonstrator and/or test-fleet fuel-cell-powered electric vehicles have been fielded by 25 automakers worldwide since General Motors (Detroit, Mich., U.S.) unveiled the first, its GM Electrovan, in 1966. The most recent to the market is the Toyota Mirai. There have also been a host of fuel-cell-powered trucks, buses, racing vehicles, a motorcycle, four rail locomotives and some ocean vessels, including submarines. Fuel cells also power an increasing number of stationary systems that provide heat and light to other structures. According to global analyst IHS Markit (London, U.K.), use of battery-electric vehicles (BEVs) is expected to expand to as many as 90% of all vehicles in western countries by 2025, but hydrogen fuel cell vehicles (HFCVs) may quickly become a more aggressive competitor as new technologies develop. Eleven large corporations have formed the Japan H2 Mobility cooperative and the German counterpart H2 Mobility Germany, and both have targets to increase H2 fueling stations, up from 100 and 69 currently. Though California lags in stations (36), it boasts the most HCVs on the road at 4,410. Multi-client studies by IHS Markit forecast a significant share of hydrogen in the mobility sector by 2050, led by global truck and car manufacturers like Toyota, Nikola Motors, Hyundai and Bosch. IHS Markit suggests that in order for this growth to take place, hydrogen prices will first need to come down from current levels.
There are also opportunities in non-transportation sectors including decarbonizing energy use for industry and local electrical power. The U.K. is exploring the possibility of converting its natural gas grid to H2 with its ongoing North of England H21 project, due to begin in 2028. Residential and commercial heating and cooling accounts for about 40% of final energy demand in Europe.
Composites can make up the bipolar plates, end plates, fuel tanks and other system components of proton exchange membrane fuel-cell (PEMFC) systems, still the leading type. In the past, thermoset materials were thought to be limited to lower volume and stationary applications, due to their longer mold cycle times, higher scrap rates and an inability to produce molded composite plates as thin as stamped metal plates. More recently, however, these issues have been overcome, providing a clear advantage for composites over metals in high-temperature and low-temperature PEMFCs where power density is a secondary requirement. Chopped carbon fiber and graphite-filled/vinyl ester bulk molding compounds (BMCs) are finding wide use in bipolar plates for low-temperature PEMFCs. BMC cost has declined significantly as volumes have increased. Similarly, molding cycles once measured in minutes are now routinely completed in seconds, due to formulation improvements and the ability to make thinner plate cross sections.
Chopped carbon fiber is also finding use as a porous paper backing material for gas diffusion layers in PEMFCs. Prepared by wet laying chopped PAN-based fibers, these can be manufactured in high volumes and low thickness. SGL’s (Wiesbaden, Germany) SIGRACET gas diffusion layers are being used by Hyundai Motor Group’s (Seoul, South Korea) new NEXO fuel-cell vehicle. Accordingly, SGL has increased SIGRACET production at its Meitingen facility.
Toyota Motor Corp. (Tokyo, Japan) began selling its Sora fuel cell bus in March 2018, and it was the first such vehicle to receive type certification in Japan. The company plans to introduce more than 100 Sora fuel cell buses in Tokyo, ahead of the Olympic and Paralympic Games in 2020, and launched an updated version of the bus in August 2019. Teijin Carbon (Tokyo, Japan) announced it has developed a multi-material roof cover for the Sora comprising carbon fiber composites, aluminum and engineered plastics. The part is manufactured in one piece with complex shapes and is suitable for mass production.
Hydrogen-powered fuel cells are also being developed for aircraft, with prototypes launched in 2019 by Alaka’i Technologies (Hopkinton, Mass., U.S.) and ZeroAvia (Hollister, Calif., U.S.). The Skai, developed by Alaka’i, features a carbon fiber composite airframe and landing skids, and is said to be the first eVTOL powered entirely by hydrogen fuel cells. ZeroAvia is flying a Piper Malibu refit with carbon fiber composite hydrogen tanks.
Skai eVTOL. Source | Alaka’i Technologies
Even though hydrogen fuel cells appear to be gaining momentum, the automotive industry, for now, continues to put more of its eggs in the battery power basket. Though some market analysts claim composites are not needed for battery electric vehicles, others disagree. “There are a lot of electric motor applications for CFRP with tremendous opportunities for us,” said James Austin in an interview during his tenure as president of North Thin Ply Technology (NTPT, Penthalaz-Cossonay, Switzerland), a developer of lightweight, spread tow and thin ply composite materials and manufacturing systems. “I think there is a lot more going on here than people appreciate. We think electric vehicles (EVs) will have a significant impact on the future of our company.”
Another company supplying into battery boxes is SHD Composites (Sleaford, Lincolnshire, U.K.) with its prepregs using biobased polyfurfuryl alcohol (PFA) thermoset resin that meets phenolic performance. Its PS200 prepreg meets fire protection requirements for aircraft batteries mandated by the European Aviation Safety Agency (EASA), and is already in use at manufacturers of general aviation aircraft, where simulated battery fire testing showed an inside temperature of 1,100°C, while the outside never exceeded 250°C and the battery box never burned or decomposed. Composites Evolution (Chesterfield, U.K.) also supplies PFA prepregs reinforced with flax, glass, aramid, basalt or carbon fiber, and has passed flame, smoke and toxicity (FST) testing for aircraft and rail.
Williams Advanced Engineering (Grove, Oxfordshire, U.K.), showcased structural CFRP battery box enclosures for its lightweight and scalable FW-EVX vehicle platform. Located within the car’s aluminum and CFRP monocoque are 38 battery modules, providing the EV’s power. Each 136-millimeter-wide battery module contains 10 pouch-type lithium ion batteries (think thin, as for a laptop) supplied by LG Chem (Seoul, South Korea). Pouches are stacked and protected within a CFRP box. Each of the 38 battery module boxes are made using flat CFRP sheet and the highly automated 223 process that Williams is patenting. Portions of the sheet for the box faces are cured, leaving flexible uncured hinges in between. These allow for folding of the partially cured sheet into a box, followed by final cure and bonding to produce a rigid enclosure. Each box is an impact-resistant, load-bearing exoskeleton, aiding in crash safety. The boxes are positioned and secured together to provide significant torsional and bending stiffness through the monocoque, which allows designers to reduce weight in other structures, increasing the vehicle’s fuel economy and performance.
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