Cornell scientists develop low-cost method to restore EV battery range
What if instead of investing billions into battery recycling plants, you could simply give your aging electric vehicle battery a scrub and get all that lost range back?That is near the mark of what Cornell University scientists have demonstrated through a process called Direct Electrode-to-Electrode Regeneration, or DEER.
Currently, the foreseen solution to the tsunami of retired lithium-ion battery packs from the US and Chinese EV boom is pyrometallurgy, which involves shredding batteries into a corrosive mix before extreme heat separates out cobalt, lithium, nickel, aluminum and manganese for reuse.
Much of the tonnage that goes into these circuits consists of usable EV battery packs that are charging and discharging at about 70-80% of their previous maximum capacity.
Through DEER, Cornell scientists showed that if extracted from their battery apparatus and given an electrochemical bath, electrodes inside lithium-ion batteries can gain back up to 95% of their maximum charge.
The method reverses the process through which lithium-ion batteries lose range. Over hundreds of charge and discharge cycles, a thick substance called solid electrolyte interphase (SEI) builds up on the electrodes and impedes the flow of electrons. If dunked in a bath of 1,3-dimethyl-2-imidazolidinone (DMI), the SEI layer is removed and the electrodes can be replaced in the battery pack.
“This process not only reverses interphase growth, but also leaves a thin lithium fluoride layer that slows down SEI growth in subsequent cycles,” wrote Nachiket Mhatre at Slashgear.
Batteries cleaned of SEI took longer to lose charge than virgin batteries. Once substantial charging potential had been lost for a second time, a second DMI bath again replenished the battery’s range, although to a lesser extent.
The method only works if the cause of capacity loss is SEI buildup. If the battery is losing capacity because of structural damage or lithium loss, DEER cannot help.
DEER costs less per kilogram than traditional pyrometallurgy – $15.25 per kg compared with $26.31 per kg. The cost could be brought down further if the DMI solution, which makes up around 62% of the total costs, can be recovered.
“This electrode-level regeneration framework provides a scalable pathway toward closed-loop battery manufacturing with substantially reduced cost, energy consumption, and greenhouse gas emissions,” the authors wrote in the study published in the journal Energy and Environmental Science.
