Billions of dead lithium-ion batteries, including many from electric vehicles and cell phones, are accumulating because there is no cost-effective process to revive them.

Now, Princeton researchers have developed an inexpensive, sustainable way to make new batteries from used ones and have spun off a company to scale up the innovation.

“People … give us their dead batteries [and] receive back from us new pristine cathode materials for new batteries cheaper than they could manufacture on their own,” said Chao Yan, co-founder and CEO of Princeton NuEnergy and a postdoctoral research associate in mechanical and aerospace engineering. 

Princeton NuEnergy’s researchers combined expertise from diverse fields to solve a longstanding problem: how to turn spent cathode materials — the expensive part of a lithium-ion battery, containing elements such as cobalt, nickel, manganese and lithium — into pristine new cathodes.

Current technologies rely on harsh chemicals and high temperature, energy-intensive processes to break down spent batteries to their elemental components. Instead, Princeton NuEnergy is upgrading and renewing the cathodes themselves in a form of direct recycling. This method reduces water use by approximately 70%, and energy use and emissions by 80%.