Commentary It’s one of the biggest unanswered questions as electric vehicles (EVs) rapidly proliferate: What will happen to all of the degraded lithium-ion batteries once the vehicles reach the end of their lives? “Recycling” is the optimistic solution offered by EV advocates and supporters of green technology, but will battery recycling actually make economic and environmental sense? According to the International Energy Agency, a predicted 23 million EVs sold worldwide in 2030 could lead to 5,750,000 tonnes of retired batteries by 2040, and this waste will keep piling up as EVs replace internal combustion engine vehicles. The prospect is of pressing interest to a team of scientists and engineers in the UK, which recently published a paper on the “financial viability of electric vehicle lithium-ion battery recycling” in the journal iScience. “If recycling remains unprofitable, battery waste mountains could build up, which, if uncontrolled, bear a significant environmental and safety risk, as toxic …