Reducing the use of scarce metals — and recycling them — will be key to the world’s transition to electric vehicles.
The age of the electric car is upon us. Earlier this year, the US automobile giant General Motors announced that it aims to stop selling petrol-powered and diesel models by 2035. Audi, based in Germany, plans to stop producing such vehicles by 2033. Many other automotive multinationals have issued similar road maps. Suddenly, major carmakers’ foot-dragging on electrifying their fleets is turning into a rush for the exit.
The electrification of personal mobility is picking up speed in a way that even its most ardent proponents might not have dreamt of just a few years ago. In many countries, government mandates will accelerate change. But even without new policies or regulations, half of global passenger-vehicle sales in 2035 will be electric, according to the BloombergNEF (BNEF) consultancy in London.
This massive industrial conversion marks a “shift from a fuel-intensive to a material-intensive energy system”, declared the International Energy Agency (IEA) in May1. In the coming decades, hundreds of millions of vehicles will hit the roads, carrying massive batteries inside them (see ‘Going electric’). And each of those batteries will contain tens of kilograms of materials that have yet to be mined.
Anticipating a world dominated by electric vehicles, materials scientists are working on two big challenges. One is how to cut down on the metals in batteries that are scarce, expensive, or problematic because their mining carries harsh environmental and social costs. Another is to improve battery recycling, so that the valuable metals in spent car batteries can be efficiently reused. “Recycling will play a key role in the mix,” says Kwasi Ampofo, a mining engineer who is the lead analyst on metals and mining at BNEF.
Battery- and carmakers are already spending billions of dollars on reducing the costs of manufacturing and recycling electric-vehicle (EV) batteries — spurred in part by government incentives and the expectation of forthcoming regulations. National research funders have also founded centres to study better ways to make and recycle batteries. Because it is still less expensive, in most instances, to mine metals than to recycle them, a key goal is to develop processes to recover valuable metals cheaply enough to compete with freshly mined ones. “The biggest talker is money,” says Jeffrey Spangenberger, a chemical engineer at Argonne National Laboratory in Lemont, Illinois, who manages a US federally funded lithium-ion battery-recycling initiative, called ReCell.
The first challenge for researchers is to reduce the amounts of metals that need to be mined for EV batteries. Amounts vary depending on the battery type and model of vehicle, but a single car lithium-ion battery pack (of a type known as NMC532) could contain around 8 kg of lithium, 35 kg of nickel, 20 kg of manganese and 14 kg of cobalt, according to figures from Argonne National Laboratory.
Analysts don’t anticipate a move away from lithium-ion batteries any time soon: their cost has plummeted so dramatically that they are likely to be the dominant technology for the foreseeable future. They are now 30 times cheaper than when they first entered the market as small, portable batteries in the early 1990s, even as their performance has improved. BNEF projects that the cost of a lithium-ion EV battery pack will fall below US$100 per kilowatt-hour by 2023, or roughly 20% lower than today (see ‘Plummeting costs of batteries’). As a result, electric cars — which are still more expensive than conventional ones — should reach price parity by the mid-2020s. (By some estimates, electric cars are already cheaper than petrol vehicles over their lifetimes, thanks to being less expensive to power and maintain.).
To produce electricity, lithium-ion batteries shuttle lithium ions internally from one layer, called the anode, to another, the cathode. The two are separated by yet another layer, the electrolyte. Cathodes are the main limiting factor in battery performance — and they are where the most valuable metals lie.
The cathode of a typical lithium-ion battery cell is a thin layer of goo containing micro-scale crystals, which are often similar in structure to minerals that occur naturally in Earth’s crust or mantle, such as olivines or spinels. The crystals pair up negatively charged oxygen with positively charged lithium and various other metals — in most electric cars, a mix of nickel, manganese and cobalt. Recharging a battery rips lithium ions out of these oxide crystals and pulls the ions to a graphite-based anode where they are stored, sandwiched between layers of carbon atoms.
Above all, lithium-ion batteries will stay with us for some time before any viable alternatives are widely accepted technically and economically. The main now trends for EV batteries are to reduce the amount of scarce metals in EV batteries, i.e., lithium and cobalt, while retaining or improving their performances. In addition, the relevant Governments, research institutions and enterprises should work together to increase the percentage of recycled EV batteries by providing regulations, funds and infrastructure.