AI Found a ‘Magic Potion’ That Can Bring Dead Batteries Back to Life
Electric vehicles leave behind mountains of dead lithium-ion batteries. A new “injection” brings them back to life
Malte Mueller/Getty Images
A team of researchers in China has found a way to bring dead lithium-ion batteries back to life, potentially reducing both the amount of waste that’s quickly piling up from spent electric vehicle (EV) batteries and the need to produce as many new ones.
“The team’s work is revolutionary because it provides a new idea to reuse end-of-life batteries,” says Jiangong Zhu of Tongji University in Shanghai, who researches battery use in EVs and was not involved in the new study, which was published recently in Nature.
The amount of spent lithium-ion batteries that need disposal is expected to soar from an estimate of 900,000 metric tons this year to 20.5 million metric tons by 2040, according to a report released by the United Nations Development Program last September. As the world’s leader in deploying EVs, China is already handling 2.8 million metric tons of retired cells ever year, according to Huang Jianzhong, chairman of China Electronic Energy Saving Technology Association, a government-approved trade body.
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With consumer markets and waste piles both growing rapidly, Yue Gao, a chemist at Fudan University in Shanghai, and his colleagues anticipated a rising demand for longer-life lithium-ion batteries.
An EV battery usually reaches the end of its lifetime, or when its capacity drops below 80 percent of its original level, after about eight to 10 years. The battery accounts for around 40 percent of the cost of the entire vehicle.
Gao and his colleagues wanted to find a molecule that could replenish a dead cell by infusing it with lithium ions. But “we had no idea what kinds of molecules could do that job or what their chemical structures would be, so we used machine learning to help us,” says Chihao Zhao, a Ph.D. student at Fudan University, who is a member of Gao’s team but was not a co-author of the new study.
Lithium ions were restored to a spent battery pack by injecting an electrolyte solution.
The researchers used an artificial intelligence model trained on the rules of chemistry. They fed it a database of electrochemical reactions and had it look for molecules that would meet their requirements, such as dissolving well in an electrolyte solution and being relatively cheap to produce. The model recommended three candidates, and the team identified one of them, a salt called lithium trifluoromethanesulfinate (LiSO2CF3), as ideal.
The researchers tested this lithium-ion salt by dissolving it in an electrolyte solution, which allows ions to pass between a cell’s positive and negative terminals. Gao likens this to giving a human patient an IV. “If we can give an injection to a sick person to help them recover,” he says, “why can’t we have a magic potion for drained batteries, too?”
Gao and his colleagues found that the chemical mixture could significantly prolong the lifespan of a lithium iron phosphate (LFP) battery cell. An LFP battery that powers an EV can typically be charged and then discharged about 2,000 times before it is considered “dead” (when its capacity is below the 80 percent mark). By adding the electrolyte whenever the battery neared that threshold, the team was able to restore most of the cell’s capacity each time—and it carried on working almost as well as a new battery. By the end of the experiment, the cell regained 96 percent capacity after nearly 12,000 charge-discharge cycles.
A follow-up experiment showed the method also worked on NMC (nickel, manganese and cobalt) lithium-ion batteries, Gao says.
Fudan University is currently working with China-based battery-material maker Zhejiang Yongtai New Material to commercialize the method, according to a social media post published by Yongtai. Gao envisions a widespread system of “battery-boosting stations” where EV owners will be able to bring dead power sources to be rejuvenated.
The idea is “promising,” says Chenguang Liu of Xi’an Jiaotong-Liverpool University in China, who researches battery materials and was not involved in the study. But he cites a few challenges. For example, the method will need to be made compatible with various battery chemistries—and the safety of the revived cells must be tested.
And EV power comes not from a single, simple cell but from a battery pack that can comprise hundreds or even thousands of cells, along with heat-control systems and other components. “We have only conducted experiments on cells, and we need to find a way to apply it onto a whole battery pack,” Gao says.
His team’s method is the closest thing yet to a “direct-recycling process” for EV batteries in China today, says Hans Eric Melin, an analyst of battery reuse and recycling and managing director of Circular Energy Storage, a London-based consultancy. (In China, some degraded EV batteries are currently used to power other products that require lower energy outputs, such as electric mopeds and energy storage stations. Others are crushed and shredded into industrial waste called “black mass,” from which valuable raw materials, such as lithium and graphite, can be harvested.)
Melin believes there could be commercial opportunities for the researchers’ proposal—though he says the market is likely to be small because the lifespan of an EV battery can be as long as 15 years. It will also require battery packs that are designed in a way to allow for injections of the electrolyte, he notes.
“The question,” he adds, “is whether the benefits are worth it if [the required changes] in some way interfere with other design aspects necessary for the battery’s performance.”
