CO and water help pull lithium from dead batteries

"The team, from the Chinese Academy of Sciences and Beijing Institute of Technology, recently published their findings in Nature Communications. According to their research, the process not only avoids conventional leaching chemicals and extreme heat to extract lithium from old batteries, but it also uses carbon dioxide in what the authors call a sequestration step, and turns other battery transition metals into new catalysts - with CO₂-rich water doing most of the chemical work."

"According to the researchers, more than 95 percent of the lithium in spent batteries can be recovered after mechanochemically treating the cathodes and then leaching them with CO₂-rich water, where carbonic acid formation enables selective separation of lithium as water-soluble lithium bicarbonate. "Conducted under ambient conditions without additional grinding aids or leaching agents, this method minimizes environmental impact," the boffins explained. Other "methods often require substantial reagent inputs, produce hazardous emissions and secondary pollution, and generate leaching residues.""

"Those residues, the team explained, then typically have to be processed using acid leaching to be converted into salt solutions before reuse, which further reduces their value. The "three-in-one" strategy developed by the team also eliminates those additional processing needs, with transition metals in the cathode, like cobalt, nickel, and the like, "simultaneously transformed into high-performance oxygen evolution reaction (OER) catalysts," the researchers explained. OER catalysts are a key component in converting electrical energy into stored chemical energy in water-splitting systems"

Mechanochemical pretreatment of spent Li-ion cathodes followed by leaching with CO₂-rich water enables recovery of more than 95% of lithium as water-soluble lithium bicarbonate. Carbonic acid formed in the CO₂-rich leachate selectively separates lithium without extreme heat or conventional leaching chemicals. The process operates under ambient conditions without additional grinding aids or leaching agents, reducing reagent inputs, hazardous emissions, secondary pollution, and leaching residues. The method avoids subsequent acid leaching of residues by concurrently converting cathode transition metals such as cobalt and nickel into high-performance oxygen evolution reaction catalysts. Near-term market-scale disruption from this method remains unlikely.

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