Making Rechargeable Batteries More Sustainable With Fully Recyclable Components

Rechargeable solid-state lithium batteries are an emerging technology that could one day power cell phones and laptops for days on a single charge. They offer vastly improved energy density and are a safer alternative to the flammable lithium-ion batteries currently used in consumer electronics—but they’re not environmentally friendly. Current recycling methods focus on limited recovery of the metals inside the cathodes, with everything else going to waste.

A team of researchers at Pennsylvania State University may have solved this problem. Led by Enrique GomezThe team has reconfigured the design of solid-state lithium batteries so that all of their components can be easily recycled. They published their results in the journal Energy Messages from ACS.

“As the need for rechargeable batteries grows, we need to think about the end of life of this technology,” Gomez said. “We hope our work will highlight the recycling potential of solid-state batteries, with the help of some key design elements.”

Traditionally, most of the battery’s core components go to waste because they mix during the recycling process, forming a “black mass,” according to the researchers. This black mass is rich in materials needed for batteries, but separating it remains a challenge. In solid-state batteries, the use of solid electrolytes exacerbates this problem, as they mix with the black mass.

To facilitate the separation of these components from the other metal components in the coin battery, the researchers introduced two layers of polymer at the interfaces between the electrode and electrolyte before beginning the recycling process.

“We proposed that by dissolving the polymer layer during the recycling process, you can easily separate the electrode from the electrolyte. Without the polymer layer separating them, you would have the electrode and electrolyte mixed together, making them difficult to recycle,” said Yi-Qin Lan, a doctoral student in chemical engineering and first author of the paper.

Once the researchers were able to separate the components, they made a composite of the recovered metals and electrodes using cold sintering — a process of fusing powder-based materials into dense shapes at low temperatures through pressure applied with solvents.Developed in 2016By a team of researchers led byClive Randall President of Pennsylvania State UniversityMaterials Research InstituteDistinguished Professor of Materials Science and Engineering. Gomez and his team The possibility of recycling solid-state electrolytes using cold sintering has recently been demonstrated.

“We used cold sintering to combine the recovered electrodes with the recovered solid electrolyte powders, and then reconstructed the battery by adding polymer layers,” said Bo Hao Lai, a chemical engineering doctoral student and co-author of the research. “This enables us to fully recycle the battery, which we can then recycle again after use.”

After testing its performance, they found that the rebuilt battery achieved between 92.5% and 93.8% of its original discharge capacity.

“While the commercialization of all-solid-state lithium batteries is still in its early stages, our work provides important insights and ideas for designing recyclable versions of these batteries,” Lan said. “While we’re not there yet, the long-term goal is to apply this innovation to larger batteries that can be used in devices such as cell phones and laptops, once all-solid-state technology becomes more widespread.”

reference: Lan YC, Lai PH, Vogt BD, Gomez ED. Interface layers to enable all-solid-state lithium batteries to be recycled. A message from ACS Energy. 2024;9(7):3324-3334. Buzz: 10.1021/acsenergylett.4c01153

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