Innovative method for recycling battery parts avoids crushing or melting
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Researchers have demonstrated a new recycling method for batteries that replenishes lithium in electrodes while keeping the existing structure intact, with performance of the reborn battery nearly as good as new.
The proliferation of electric cars, smartphones and portable devices is leading to an estimated 25 per cent increase globally in the manufacturing of rechargeable batteries each year. Many raw materials used in the batteries, such as cobalt, may soon be in short supply. The European Commission is preparing a new battery decree, which would require the recycling of 95 per cent of the cobalt in batteries, yet existing battery recycling methods are far from perfect.
Researchers at Aalto University, Finland, have discovered that electrodes in lithium batteries containing cobalt can be reused after being newly saturated with lithium. In comparison to traditional recycling, which typically extracts metals from crushed batteries by melting or dissolving them, the new process saves valuable raw materials and energy.
"In our earlier study of how lithium cobalt oxide batteries age, we noticed that one of the main causes of battery deterioration is the depletion of lithium in the electrode material. The structures can nevertheless remain relatively stable, so we wanted to see if they can be reused," said Professor Tanja Kallio, Aalto University.
Rechargeable lithium-ion batteries have two electrodes between which electrically charged particles move. Lithium cobalt oxide is used in one electrode and, in most batteries, the other is made of carbon and copper.
In traditional battery recycling methods, some of the batteries' raw materials are lost and lithium cobalt oxide turns into other cobalt compounds, which require a lengthy chemical refinement process to turn them back into electrode material. The new method sidesteps this painstaking process: by replenishing the spent lithium in the electrode through an electrolysis process, commonly used in industry, the cobalt compound can be directly reused.
The results show that the performance of electrodes newly saturated with lithium is almost as good as that of those made of new material. Kallio believes that with further development the method would also work on an industrial scale.
"By reusing the structures of batteries we can avoid a lot of the labour that is common in recycling and potentially save energy at the same time. We believe that the method could help companies that are developing industrial recycling," Kallio says.
The researchers now intend to see if the same method could also be used with the nickel-based batteries of electric cars. Their research is published in the journal ChemSusChem.
A separate study, led by a researcher at the Yale School of the Environment's Center for Industrial Ecology and published earlier this week, suggested that electronic waste (e-waste) is in fact on the decline, contrary to the general perception, with older and bulkier electronics disappearing from the waste stream.
The study found that the total mass of e-waste generated by the US population has been declining since 2015. The biggest contributor to this decline is the disappearance of the large, bulky cathode-ray tube (CRT) televisions and computer monitors, according to Callie Babbitt, one of the study's authors and a professor at Rochester Institute of Technology's Golisano Institute for Sustainability. Since about 2011, CRT displays have been on the decline in the waste stream, helping to lead the overall decline in total e-waste mass.
The sheer number of electronic devices entering the waste stream is also levelling off or slightly declining, said Babbitt and Yale's Shahana Althaf, lead author of the study. This is due to something that Babbitt terms "convergence": gaming consoles, for example, can act as DVD players; smartphones are also cameras and video recorders. In the past, says Babbitt, people needed separate devices for each of those applications.
The study, published in the Journal of Industrial Ecology, suggests that e-waste regulations need rethinking. "If you look at the state laws that exist in many places for e-waste recycling, many of them set their targets based on product mass," said Babbitt. As the overall mass of e-waste declines, meeting those targets becomes more difficult. Moreover, said Babbitt, the main goal of these regulations had been to keep electronics with high levels of lead and mercury out of landfills, where they can eventually leach into the surrounding environment.
A more pertinent concern today is how to recover elements such as cobalt (used in lithium-ion batteries) or indium (found in flat-panel displays). These elements aren't as environmentally toxic; rather, they are relatively scarce in the Earth's crust, so failing to recapture them for reuse in new electronics is wasteful. "The e-waste recycling system is somewhat backwards-looking," said Babbitt.
Althaf suggests that a shift in e-waste recycling to capture more of these critical elements could help the US secure its supply of the ingredients required for manufacturing electronic devices. Geopolitical uncertainties can pose threats to what Althaf terms "mineral security" for the US: "People are slowly realising the need to ensure domestic supply."
Rather than mining the ore from the Earth's crust, capturing the elements from electronic waste could instead provide these crucial elements. In addition to mineral security, this would reduce the environmental destruction that traditional mining often entails.
E-waste recycling in the US is regulated at the state level, with only half of the states having e-waste recycling laws. That leads to a patchwork of regulations which makes it harder for companies to navigate if they want to make their products easier to recycle, said Babbitt. A more holistic, federal approach could help increase the overall capture of rare elements. Ultimately, we should "see waste as a resource", Althaf said: an opportunity, rather than a problem.
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