A photo of the electrochemical cell set-up in the Rice lab. Credit: Jorge Vidal / Rice University
As global electric vehicle adoption accelerates, end-of-life battery packs are quickly becoming a major waste stream. Lithium is costly to mine and refine, and most current recycling methods are energy- and chemical-intensive, often producing lithium carbonate that must be further processed into lithium hydroxide for reuse.
Instead of smelting or dissolving shredded battery materials ("black mass") in strong acids, a team of engineers at Rice University has developed a cleaner approach by recharging the waste cathode materials to coax out lithium ions into water, where they combine with hydroxide to form high-purity lithium hydroxide.
"We asked a basic question: If charging a battery pulls lithium out of a cathode, why not use that same reaction to recycle?" said Sibani Lisa Biswal, chair of Rice's Department of Chemical and Biomolecular Engineering and the William M. McCardell Professor of Chemical Engineering. "By pairing that chemistry with a compact electrochemical reactor, we can separate lithium cleanly and produce the exact salt manufacturers want."
In a working battery, charging pulls lithium ions out of the cathode. Rice's system applies that same principle to waste cathode materials such as lithium iron phosphate. As the reaction begins, lithium ions migrate across a thin cation-exchange membrane into a flowing stream of water. At the counter electrode, another simple reaction splits water to generate hydroxide. The lithium and hydroxide then combine in the water stream to form lithium hydroxide with no need for harsh acids or extra chemicals.
The research, recently published in Joule, demonstrates a zero-gap membrane-electrode reactor that uses only electricity, water and battery waste.
Credit: Joule (2025). DOI: 10.1016/j.joule.2025.102197
In some modes, the process required as little as 103 kilojoules of energy per kilogram of black mass—about an order of magnitude lower than common acid-leaching routes (not counting their additional processing steps). The team scaled the device to 20 square centimeters, ran a 1,000-hour stability test and processed 57 grams of industrial black mass.
"Directly producing high-purity lithium hydroxide shortens the path back into new batteries," said Haotian Wang, associate professor of chemical and biomolecular engineering and co-corresponding author of the study alongside Biswal. "That means fewer processing steps, lower waste and a more resilient supply chain."
The process produced lithium hydroxide that was more than 99% pure—clean enough to feed directly back into battery manufacturing. It also proved highly energy efficient, consuming as little as 103 kilojoules of energy per kilogram of waste in one mode and 536 kilojoules in another. The system showed both durability and scalability, maintaining an average lithium recovery rate of nearly 90% over 1,000 hours of continuous operation.
The approach also worked across multiple battery chemistries, including lithium iron phosphate, lithium manganese oxide and nickel-manganese-cobalt variants. Even more promising, the researchers demonstrated roll-to-roll processing of entire lithium iron phosphate electrodes directly from aluminum foil—no scraping or pretreatment required.
"The roll-to-roll demo shows how this could plug into automated disassembly lines," Wang said. "You feed in the electrode, power the reactor with low-carbon electricity and draw out battery-grade lithium hydroxide."
Next, the researchers plan to scale up the technology further by developing larger-area stacks, increasing black mass loading and designing more selective, hydrophobic membranes to sustain high efficiency at greater lithium hydroxide concentrations. They also see posttreatment—concentrating and crystallizing lithium hydroxide—as the next major opportunity to cut overall energy use and emissions.
"We've made lithium extraction cleaner and simpler," Biswal said. "Now we see the next bottleneck clearly. Tackle concentration, and you unlock even better sustainability."
More information: Yuge Feng et al, A direct electrochemical Li recovery from spent Li-ion battery cathode for high-purity lithium hydroxide feedstock, Joule (2025). DOI: 10.1016/j.joule.2025.102197
