EV batteries are very hard to recycle, but some of their components, especially nickel and cobalt, are valuable enough to repay the investment.
Millions of electric vehicles are now being sold around the world, containing large lithium-ion batteries. For reasons of both safety and sustainability, these batteries must be recycled or carefully disposed of when the cars reach the end of their driving lives.
Elsa Olivetti, Jerry McAfee (1940) Professor in Engineering in the Department of Materials Science and Engineering (DMSE) and co-director of the MIT Climate and Sustainability Consortium, says that like all forms of recycling, the EV battery recycling business will be driven by which materials are most profitable to salvage. In the case of lithium-ion batteries, she says, that most often means metals such as nickel and cobalt. These materials are expensive and often mined in lower-income countries under problematic conditions.
Saving nickel and cobalt from old batteries could reduce the amount that needs to be newly mined, especially if recyclers deliver on claims that more than 95 percent of these materials can be salvaged. However, as the world transitions from gas-powered to electric vehicles, the demand for these materials will far outpace the supply from recycling, so mining metals such as cobalt will still be necessary.
An EV battery contains much more than just nickel and cobalt, however. It is an amalgamation of plastics, copper, aluminum, and other materials, some of which won’t be recovered completely because they aren’t valuable enough to be worth the trouble. The materials that are not recycled must be sent to a landfill or, if they are too hazardous, safely stored.
To be recycled, EV batteries must first be dismantled, which is no simple task because batteries are not standardized. The packs from a Tesla, BMW, and Nissan EV are different sizes, containing differently-shaped battery cells joined together by welds and other connections that must be broken down. This complexity makes the process more expensive and dangerous.
“The significant challenge in battery recycling is the variability in chemistry and form factor, and that we have to be cautious to discharge them when they are recovered,” Olivetti says. That’s especially important because old or broken lithium-ion batteries can catch fire, which adds to the danger of stockpiling them for disposal.
Once the old batteries are taken apart, there are several possible methods for materials recycling. “Pyrometallurgical” processes subject the materials to very high temperatures in a furnace to recover some of the component metals. “Hydrometallurgical” processes subject the battery parts to chemical solutions dissolved in water to leach out the desired metals. Neither method is perfect: pyrometallurgical recycling uses a lot of energy, while hydrometallurgical recycling requires components to be broken down even further beforehand.
It’s possible that many electric car batteries will be reused, not recycled. An older EV battery may no longer be useful for long-distance driving but could still have enough storage capacity to find a second life elsewhere. For example, Olivetti says, blocks of old batteries could be used to ease strain on the power grid by providing backup electricity when it’s needed most. In 2018, Nissan experimented with this idea by using new and old batteries from their Leaf EV model to power the Ajax Amsterdam soccer stadium.
“But we have to be sure we understand the state of the battery’s health,” Olivetti says. “And that’s a challenge.”
Published September 5, 2023
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