Cornell's Battery Bath Skips Shredding, Cuts Costs 56%

What actually kills a used lithium-ion battery

A lithium-ion cell does not lose capacity because its lithium runs out. It loses capacity because a layer called the solid electrolyte interphase, or SEI, builds up on the electrode surface every time the battery charges and discharges, gradually blocking the ion movement that makes the battery work. By the time a battery reaches 70 to 80 percent of its original capacity, roughly the point at which electric-vehicle packs are typically retired, that layer, not a shortage of active material, is doing most of the damage, according to Cornell University's own announcement of the research.

The process Cornell calls DEER

A team led by Vibha Kalra, the Fred H. Rhodes Professor of Chemical Engineering at Cornell, developed a method called direct electrode-to-electrode regeneration, or DEER, that removes a spent battery's electrodes intact, still attached to their current collectors, and places them in a bath of 1,3-dimethyl-2-imidazolidinone, a solvent Cornell's release refers to by its abbreviation, DMI. The solvent dissolves the built-up interphase layer on both the cathode and the anode without shredding or powdering either electrode, restoring up to 95 percent of the battery's original capacity, Cornell said. Kiwon Kim, a postdoctoral researcher, is the paper's lead author; Cornell doctoral student Chenlu Yang and assistant professor Shuwen Yue also worked on the project, alongside Sabine Gallagher of Argonne National Laboratory's ReCell Center, which ran the techno-economic and environmental-impact modeling. The work was published in the journal Energy & Environmental Science on June 9, 2026, and independently covered by TechXplore, which cited the same 95 percent figure and the paper's DOI, 10.1039/d6ee01118g.

"We repair them, as is, without shredding or powdering them, and then put them back into a new battery," Kalra said, according to Cornell's release. "The dissolution basically helps the battery recover its capacity."

What that skips, and what it costs

Every commercial lithium-ion recycling process in wide use today shreds spent cells into a mixed powder called black mass, then separates the metals out with heat or acid before remanufacturing new electrodes from scratch. Cornell and Argonne's modeling found DEER cuts recycling manufacturing costs by 56 percent compared with that shred-and-rebuild approach, largely because it skips the energy-intensive step of resynthesizing electrode material that was never actually consumed, only coated in interphase buildup. Argonne's analysis also found the process reduces harmful air pollutants and water consumption relative to conventional recycling, according to Cornell's release, though Cornell's announcement did not publish exact figures for either reduction.

Recycling approach	Electrode handling	Cost vs. shred-and-rebuild
Conventional (shred, smelt or leach)	Destroyed into black mass	Baseline
DEER (Cornell/Argonne)	Kept intact, chemically stripped	56% lower

What DEER is not, yet

The 95 percent capacity figure and the 56 percent cost figure both come from Cornell and Argonne's own lab-scale testing and techno-economic modeling, not from a commercial recycling line. Cornell's announcement does not name a manufacturing partner, a pilot facility, or a timeline for scaling DEER beyond the laboratory, and it does not disclose how many charge cycles a DEER-regenerated electrode sustains after treatment compared with a factory-fresh one. The process is also demonstrated on cells that reached 70 to 80 percent of original capacity; Cornell's release does not say whether DEER works on packs degraded further than that threshold.

Why the shortage of raw material makes this matter now

Growing EV sales are the reason a fix for the battery-recycling bottleneck has commercial stakes at all: as more packs reach the end of their first life, the volume of nickel, cobalt and lithium locked inside them grows too, and DEER's pitch is recovering that value without the cost and emissions of full remanufacturing. Toyota's bZ EV sales have climbed even as the broader US electric-vehicle market has contracted, one sign that the population of batteries eventually needing this kind of treatment keeps growing regardless of any single quarter's sales trend. The same scrutiny of hardware claims made under real-world conditions applies here as it does to the federal safety audit now underway on Tesla's Cybercab: a laboratory result and a fleet-scale deployment are different things, and DEER has cleared only the first one so far.