The era of electric vehicles has arrived. Earlier this year, General Motors announced plans to phase out gasoline and diesel vehicles by 2035. Audi of Germany expects to stop making them in 2033. Other automakers have provided similar road maps. Suddenly, big automakers’ hesitation in electrifying their fleets has turned into a panic.
Even the most enthusiastic proponents of electrification of a personal mobility could not have predicted just a few years ago. Mandates will speed transformation in many countries. Even without additional laws or regulations, BloombergNEF (BNEF) predicts that half of global passenger vehicle sales will be electrified by 2035.
As the IEA stated on May 1, this vast industrial switch indicates a “shift from a fuel-intensive to a material-intensive energy system”. Hundreds of millions of vehicles with huge batteries will hit the roads in the coming decades and each battery will include tens of kilograms of unmined materials.
As electric vehicles take over the world, materials scientists face two significant hurdles. One is to reduce the use of rare, expensive, or hazardous metals in batteries with high environmental and societal consequences. Better battery recycling allows valuable metals from old batteries to be repurposed.
The cost of manufacturing and recycling electric vehicle (EV) batteries has already been reduced by billions of dollars, prompted by government incentives and anticipated restrictions. National research funds have also established battery research centers. Because mining metals is still cheaper than recycling them, developing techniques to recover valuable metals affordably is a significant priority.
The Lithium Future
The first task for researchers is to limit metal mining for EV batteries. Argonne National Laboratory estimates that a single-car lithium-ion battery pack (NMC532) contains roughly 8 kg lithium, 35 kg nickel, 20 kg manganese, and 14 kg cobalt.
Analysts do not see a shift away from lithium-ion batteries soon, as their cost has fallen so substantially. As compact, portable batteries, they were introduced to the market in the early 1990s and have since become 30 times cheaper. According to BNEF, the cost of a lithium-ion EV battery pack will be under $100 per kilowatt-hour by 2023, a 20% reduction (see ‘Plummeting battery costs’). As a result, electric automobiles will be cheaper than conventional cars by the mid-2020s.
Lithium-ion batteries generate power by moving lithium ions from one layer (anode) to another (cathode). The electrolyte layer separates the two. This is because cathodes are where the most valuable metals are found.
The cathode of a lithium-ion battery cell is a thin layer of goo containing micro-scale crystals that resemble minerals found in the Earth’s crust or mantles, such as olivines or spinels, in structure. Most electric automobiles use a mix of nickel, manganese, and cobalt in their crystals. A battery’s anode is made of graphite and stores lithium ions sandwiched between layers of carbon atoms.
Increasing lithium mining raises environmental concerns: existing extraction methods use a lot of energy (for rock lithium) or water (for extraction from brines). Modern methods that extract lithium from geothermal water utilizing geothermal energy are considered safer. Destructive fossil-fuel exploitation will be displaced by lithium mining.
To address the raw material concerns, some labs have begun testing low-cobalt or cobalt-free cathodes. Because more than half of the lithium ions are lost during charging, cathode materials must be carefully chosen to avoid crystallization. Arumugam Manthiram, a materials scientist at the University of Texas at Austin, says removing cobalt reduces energy density because it changes the cathode’s crystal structure and ability to bind lithium.
Manthiram is one of the experts who has shown that cobalt can be removed from cathodes without affecting performance. According to Manthiram, the cobalt-free material has the same crystal structure as lithium cobalt oxide, if not better. For this, his team optimized cathode manufacturing and added small amounts of other metals while maintaining the cathode’s cobalt-oxide crystal structure. Manthiram claims current manufacturers can quickly adopt this technology, and he formed TexPower to bring it to market within two years. Other laboratories worldwide are developing cobalt-free batteries, including Tesla, the pioneering electric vehicle manufacturer based in Palo Alto, California.
Sun Yang-Kook of Seoul’s Hanyang University produced comparable findings using cobalt-free cathodes. The process of refining nickel-rich ores requires expensive pure-oxygen atmospheres, according to Sun. However, many scholars now consider the cobalt issue solved.
The absence of cobalt will have unanticipated consequences for researchers. Currently, other elements, particularly lithium, are more expensive to mine than to recycle.
Batteries are often shredded first, turning them into a powdered mixture of all the elements required. This mix is subsequently liquefied in a smelter (pyrometallurgy) or dissolved in acid to yield its constituent elements (hydrometallurgy). Metals are then precipitated as salts.
The goal of the research is to make recycled lithium more economically viable. Because most lithium-ion batteries are made in China, Japan, and South Korea, recycling capacity is rising. For instance, Guangdong Brunp, a subsidiary of CATL, China’s largest maker of lithium-ion batteries, is capable of recycling 120,000 tonnes of batteries each year. The company can recover most of the lithium, cobalt, and nickel used in over 200,000 autos. Government policies support this: Circular Energy Storage, a London-based consultancy, claims China currently offers financial and legal incentives to battery manufacturers who use recycled materials instead of mined ones.
It is unclear whether the EU will be able to build a domestic recycling economy by 2023, as planned by the European Commission. While President Joe Biden’s administration wants to invest billions in domestic EV battery manufacture and recycling, it hasn’t suggested new restrictions beyond current legislation classifying batteries as hazardous waste that must be securely disposed of. Certain North American firms claim they can currently recover the majority of the metals contained in a battery, including lithium, at mining pricing. At the same time, analysts argue the overall economics are only favorable because of cobalt.
The chemistry of cathodes is also continually changing. The cathodes used in 10–15 years, toward the conclusion of the current car’s life cycle, may be different from today’s. The manufacturer might collect its batteries at the end of its life cycle. And batteries should be built from the ground up to be easy to use.