Engineers at Rice University have developed a cleaner, energy-efficient method to extract high-purity lithium hydroxide from used electric vehicle batteries without harsh chemicals or intensive processing.
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As electric vehicle adoption grows rapidly around the world, end-of-life battery packs are becoming a significant waste challenge. Lithium, a key ingredient in these batteries, is expensive to extract and refine, and most current recycling techniques are energy- and chemical-intensive. They typically yield lithium carbonate, which then requires additional processing to convert into battery-ready lithium hydroxide.
Instead of relying on smelting or acid-leaching shredded battery material (known as “black mass”), the Rice team has taken a different approach. They’ve designed a system that recharges waste cathode materials, coaxing lithium ions out and 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? By pairing that chemistry with a compact electrochemical reactor, we can separate lithium cleanly and produce the exact salt manufacturers want.
Sibani Lisa Biswal, Chair and the William M. McCardell Professor, Department of Chemical and Biomolecular Engineering, Rice University
In a functioning battery, charging causes lithium ions to exit the cathode. The Rice system applies this same principle to spent materials like lithium iron phosphate.
As the process starts, lithium ions pass through a thin cation-exchange membrane into a flowing water stream. Meanwhile, a parallel reaction at the counter electrode splits water to create hydroxide. These components then meet in the water stream to form lithium hydroxide, all without the need for corrosive acids or added reagents.
The team’s findings, recently published in Joule, highlight a zero-gap membrane-electrode reactor powered only by electricity, water, and battery waste. In its most efficient mode, the system used just 103 kilojoules of energy per kilogram of black mass, which is nearly ten times less than typical acid-leaching methods, even before accounting for extra processing steps.
The researchers scaled their reactor to 20 square centimeters, ran it continuously for 1000 hours, and successfully processed 57 grams of industrial black mass provided by industry partner TotalEnergies.
Directly producing high-purity lithium hydroxide shortens the path back into new batteries. That means fewer processing steps, lower waste, and a more resilient supply chain.
Haotian Wang, Study Co-corresponding Author and Associate Professor, Chemical and Biomolecular Engineering, Rice University
The system produced lithium hydroxide at over 99 % purity, making it suitable for direct use in battery manufacturing. It maintained a nearly 90 % lithium recovery rate across 1000 hours of operation and showed consistent energy efficiency, consuming between 103 and 536 kilojoules per kilogram of waste depending on the mode.
Importantly, the technique worked with several battery chemistries, including lithium iron phosphate, lithium manganese oxide, and nickel-manganese-cobalt blends. The team also demonstrated the roll-to-roll processing of lithium iron phosphate electrodes directly from aluminum foil, skipping the usual scraping or pretreatment steps.
The roll-to-roll demo shows how this could plug into automated disassembly lines. You feed in the electrode, power the reactor with low-carbon electricity, and draw out battery-grade lithium hydroxide.
Haotian Wang, Study Co-corresponding Author and Associate Professor, Chemical and Biomolecular Engineering, Rice University
Next, the team aims to scale up the technology by building larger-area reactor stacks, increasing black mass input, and developing more selective, hydrophobic membranes to maintain efficiency at higher lithium hydroxide concentrations. They also see post-processing, specifically concentrating and crystallizing the lithium hydroxide, as a key area for further energy and emissions savings.
“We’ve made lithium extraction cleaner and simpler. Now we see the next bottleneck clearly. Tackle concentration, and you unlock even better sustainability,” said Biswal.
Journal Reference:
Feng, Y., et al. (2025) A direct electrochemical Li recovery from spent Li-ion battery cathode for high-purity lithium hydroxide feedstock. DOI: 10.1016/j.joule.2025.102197. https://www.sciencedirect.com/science/article/abs/pii/S2542435125003782