Car batteries contain valuable materials including cobalt, manganese, and nickel. But getting those materials out of the battery to recycle them is expensive and challenging.

For example, car batteries are shredded at their end of life, which mixes together all of the components that previously were separated. Researchers at Argonne National Laboratory, in collaboration with Illinois startup NUMiX Materials, are using a new process called capacitive deionization for separation. 

The process leverages the electric charges of nickel, manganese, and cobalt to remove them from the shredded battery, and therefore from the waste stream. This separation method is more efficient than others. Once the materials are separated, they can be reused to build new batteries. 

“There are different separation technologies used for different purposes, based on physical principles, chemical principles, and electrochemical principles,” Argonne engineer Lauren Valentino said in a news release. ​“There’s only so much you can do with mechanical processes in the first step, so we turn to things like membrane, adsorbent and capacitive deionization technologies, which can all be used to recapture chemicals of interest.” 

Capacitive deionization also shows promise for producing biofuels. The Bioprocessing Separations Consortium, a group of researchers from six national laboratories established in 2016, is working on separation processes and technologies to convert biomass to biofuel. 

Valentino leads the group and says the capacitive deionization process is useful in bioenergy production, but it involves focusing on negatively charged molecules instead of the positively charged molecules targeted in battery recycling. Once the compounds are separated, they can be converted into hydrocarbon biofuels including renewable diesel or sustainable aviation fuel. ​

“We are just beginning to explore the different ways in which more efficient separations can make transportation more sustainable,” Valentino said. ​“There’s still much we have left to discover.”