To this end, the advent of electric vehicles (EVs) seemed an attractive option. However, the high cost and limited range of EVs have so far prevented them from becoming truly mainstream.
That said, with the advancement in battery technology and better materials, EVs are gaining increasing acceptance. Due to this, it is estimated that by 2030 the battery EVs sold will touch around 130 million and plug-in hybrid ones, 90 million, as compared to three million sold in 2017.
Materials shaping future EVs
Let’s see what the materials shaping future EVs are:
#1 Battery materials
Present-day EVs possess the capability of instant acceleration, responsive handling and fast recharging times, thanks to the huge energy-storing capacity of modern-day EV batteries and their ability to discharge quickly, safely and smoothly. Most EV batteries primarily use lithium with a mix of cobalt, graphite, manganese and nickel, besides others.
- Cobalt: Cobalt is an essential component in batteries, but its availability is proving to be a big constraint. This is because60 per cent of the world’s cobalt comes from the Democratic Republic of Congo, a country with a bad track record of exploitative labor practices in cobalt production. Finding ethically-sourced cobalt increases the cost of EVs, despite this material being fully recyclable.
- Other battery materials: The improved battery technology is now doing away with cobalt altogether. Instead, the batteries use lithium-titanate and lithium-iron-phosphate. Besides these, there is increased use of magnesium, sodium and lithium sulfur that show promise in energy density and lowered cost, as compared to lithium-ion batteries.
#2 Materials for body construction
The following materials are being used in the fabrication of EVs:
- Aluminium: Aluminium is most suited for EVs, due to the low density that makes it lightweight. This increases the range of vehicles. This material is especially ideal for EVs running purely on batteries. A case in point is the Tesla Model S that uses 661 kilograms of aluminum.
- Steel: The advanced high-strength steels (AHSS) are being increasingly used to bring down the prices of EVs. AHSS are ideal since they yield strengths in excess of 550 MPa, thereby providing strength and stiffness, as also the capability of absorbing energy during a crash. This allows the parts of EV frames to be considerably reduced in size, bringing down the overall weight of the vehicle. This is the reason why even Tesla Model 3 has gone in for AHSS. It uses 200 kilograms of it. Other models, such as Nissan Leaf and VW eGolf, uses 171 kilograms and 129 kilograms of steel, respectively.
- Composite materials: Composites materials are increasingly considered as options for aluminum and AHSS in reducing the weight of the EVs. Such materials possess excellent strength-to-weight ratio. For example, VW eGolf uses polypropylene embedded with glass fiber to fabricate battery trays. Carbon fiber composites are used by BMW i3 and i8 for their bodies. Despite the favorable strength-to-weight ratio, composite materials cost more than steel.
Other materials used in EVs
- Copper: EVs contain as much as four times the amount of copper than the conventional internal combustion engine vehicles. The use of copper in EV is primarily in the motor for rotor and stator windings. The requirement of copper is expected to shoot up to 100,000 tonnes by 2027, due to the expansion in charging infrastructure for increasing numbers of EVs.
- Rare earth metals: In order to increase the range of EVs, car manufacturers, like VW and Tesla, are replacing all-copper induction motors by permanent magnet motors. These are not only more efficient but are more cost-effective too, as compared to motors with only copper coils. The use of rare earth elements, such as neodymium, is also increasing. However, the ready availability of this metal is a huge concern, since China controls 85 percent of it.
Conclusion
The factors that make EVs a viable option are their range and price. The type of materials used and their cost holds the key to the success of EVs. Research is on to find a balance between cost and efficiency with the aim to make EVs an attractive option for buyers.