ScienceMag.org:
Cut too deep into a Tesla cell, or in the wrong place, and it can short-circuit, combust, and release toxic fumes …
That’s just one of the many problems confronting researchers
The battery pack of a Tesla Model S is a feat of intricate engineering. Thousands of cylindrical cells with components sourced from around the world transform lithium and electrons into enough energy to propel the car hundreds of kilometers, again and again, without tailpipe emissions. But when the battery comes to the end of its life, its green benefits fade. If it ends up in a landfill, its cells can release problematic toxins, including heavy metals. And recycling the battery can be a hazardous business, warns materials scientist Dana Thompson of the University of Leicester. Cut too deep into a Tesla cell, or in the wrong place, and it can short-circuit, combust, and release toxic fumes.
That’s just one of the many problems confronting researchers, including Thompson, who are trying to tackle an emerging problem: how to recycle the millions of electric vehicle (EV) batteries that manufacturers expect to produce over the next few decades. Current EV batteries “are really not designed to be recycled,” says Thompson, a research fellow at the Faraday Institution, a research center focused on battery issues in the United Kingdom.
That wasn’t much of a problem when EVs were rare. But now the technology is taking off. Several carmakers have said they plan to phase out combustion engines within a few decades, and industry analysts predict at least 145 million EVs will be on the road by 2030, up from just 11 million last year. “People are starting to realize this is an issue,” Thompson says.
Governments are inching toward requiring some level of recycling. In 2018, China imposed new rules aimed at promoting the reuse of EV battery components. The European Union is expected to finalize its first requirements this year. In the United States, the federal government has yet to advance recycling mandates, but several states, including California—the nation’s largest car market—are exploring setting their own rules.
Complying won’t be easy.
Batteries differ widely in chemistry and construction, which makes it difficult to create efficient recycling systems. And the cells are often held together with tough glues that make them difficult to take apart. That has contributed to an economic obstacle: It’s often cheaper for batterymakers to buy freshly mined metals than to use recycled materials.
Better recycling methods would not only prevent pollution, researchers note, but also help governments boost their economic and national security by increasing supplies of key battery metals that are controlled by one or a few nations. “On the one side, [disposing of EV batteries] is a waste management problem. And on the other side, it’s an opportunity for producing a sustainable secondary stream of critical materials,” says Gavin Harper, a University of Birmingham researcher who studies EV policy issues.
To jump-start recycling, governments and industry are putting money into an array of research initiatives. The U.S. Department of Energy (DOE) has pumped some $15 million into a ReCell Center to coordinate studies by scientists in academia, industry, and at government laboratories. The United Kingdom has backed the ReLiB project, a multi-institution effort. As the EV industry ramps up, the need for progress is becoming urgent, says Linda Gaines, who works on battery recycling at DOE’s Argonne National Laboratory. “The sooner we can get everything moving,” she says, “the better.”
EV batteries are constructed a bit like nested dolls. Typically, a main pack holds several modules, each of which is constructed from numerous smaller cells (see graphic, below). Inside each cell, lithium atoms move through an electrolyte between a graphite anode and a cathode sheet composed of a metal oxide. Batteries are usually defined by the metals in the cathode. There are three main types: nickel-cobalt-aluminum, iron-phosphate, and nickel-manganese-cobalt.
Now, recyclers primarily target metals in the cathode, such as cobalt and nickel, that fetch high prices. (Lithium and graphite are too cheap for recycling to be economical.) But because of the small quantities, the metals are like needles in a haystack: hard to find and recover.
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To realize direct recycling, however, batterymakers, recyclers, and researchers need to sort out a host of issues. One is making sure manufacturers label their batteries, so recyclers know what kind of cell they are dealing with—and whether the cathode metals have any value. Given the rapidly changing battery market, Gaines notes, cathodes manufactured today might not be able to find a future buyer. Recyclers would be “recovering a dinosaur. No one will want the product.”
