With the development of sustainable energy technologies, there will be an increase in the demand for precious metals used in batteries. The best way to meet this need might be to recycle old batteries.
Scientists at Rice University have created a battery recycling procedure that can remove the inert layer from battery metals, reduce their oxidation state, and make them soluble in low-concentration acid.
The lab of Rice scientist James Tour was able to recover more than 98% of the metal from various types of mixed battery waste by using its patented Joule-heating technology to quickly raise the combined cathode and anode waste to temperatures beyond 2100 degrees Kelvin.
We developed a high-yield, low-cost method of reclaiming metals directly from ‘black mass’—the combined cathode and anode waste the industry traditionally tries to recycle—that significantly reduces the environmental footprint of spent battery processing.
Jinhang Chen, Study Co-Lead Author and Graduate Student, Rice University
The new approach not only drastically reduces secondary waste streams from the polluted, acidic leaching solutions, but it also significantly shortens the time required for recycling.
Chen added, “It takes less than 20 minutes to dissolve the same amounts as opposed to 24 hours. Our findings have the potential to reduce the cost of battery waste recycling through decreased energy, water and acid consumption and lower carbon dioxide emissions.”
Weiyin Chen, a former Rice chemistry graduate student and study co-lead author, stated, “Notably, the metals’ leaching kinetics is improved from the combined effects of decomposing the passivated layer and regulating the metal valence state for the first time.”
The procedure might boost the battery recycling industry, which is anticipated to expand quickly as the batteries supplying electric vehicles and other devices reach the end of their useful lives.
Battery recycling is a very big deal, especially now. Batteries in electric vehicles last about 10 years, and many of those are coming due now, because it is been about 10 years that we have been using them.
James Tour, T.T. and W.F. Chao Professor, Chemistry, Rice University
Recycling used batteries not only helps lessen the negative effects of mining on the environment but is also a wise financial decision because many varieties of lithium-ion batteries contain higher concentrations of cobalt and nickel than natural ores.
Schematic of the battery recycling process developed by Rice University scientists that uses their signature Joule-heating technique to remove the inert layer on battery metals and lower their oxidation state, making them soluble in low-concentration acid. (Image courtesy of the Tour lab/Rice University)
Tour noted, “Currently, 95% of batteries are not recycled because we don’t have the capacity to recycle them, even as waste from electronics is increasing at an annual rate of 9%.”
Previously, Tour’s lab created a method for recycling battery anodes.
“A lot of current battery recycling processes involve the use of very strong acids, and these tend to be messy, cumbersome processes. What we found is that if you ‘flash’ the black mass, then you can easily separate out the critical metals using only low-concentration hydrochloric acid. You could say the flash liberates the metals, so they dissolve easier. We’re still using acid, but much less. That is why the economics is so much better,” he added.
The study compares the novel procedure to other existing battery recycling techniques using a life-cycle evaluation.
Chen concluded, “This study has the capacity to motivate the growth of battery waste management and contribute to the mass production of electrical vehicles at a more competitive cost by lowering the cost of battery production.”
The Air Force Office of Scientific Research (FA9550-22-1-0526), the US Army Engineer Research and Development Center (W912HZ-21-2-0050), the Basic Energy Sciences program of the Department of Energy (DE-SC0012547), and the Welch Foundation (C-2065-20210327) provided funding for this study.
Chen, W., et al. (2023) Battery metal recycling by flash Joule heating. Science Advances. doi:10.1126/sciadv.adh5131