Sandwiched inside your laptop, at the back of your smartphone, and under the hood of your dream electric car are powerful and lightweight lithium-ion batteries. Even though these batteries are found inside the technology we use every day, they are rarely recycled — which means that the valuable metals inside them are not recovered for reuse.

Researchers at Texas A&M wanted to build a battery that would be lightweight and powerful, like lithium-ion batteries, but that would be more easily recyclable. To do this, they did something that had never been done before: they built electrodes, which transfer electrical charges in and out of a battery, with degradable polymers instead of metals. Their results appear in the journal Nature.

The researchers chose polymers called polypeptides because these polymers break apart into their building blocks, amino acids, when heated with just the right amount of acid. Polypeptides are not inherently conductive, though, so the researchers chemically modified them by attaching structural units that can transfer electrons back and forth. They then built electrodes by mixing the polypeptides with carbon black, another conductive material, and a binding material to hold everything together. 

After successfully charging and draining the new batteries up to 250 times, the researchers disassembled the batteries and broke the polypeptide electrodes down into amino acids and other small molecule building blocks that could be reused to re-build battery electrodes later. Although the polypeptide batteries didn’t perform quite as well as traditional lithium-ion batteries, they are an exciting alternative because the energy storing materials inside them were easily recovered. By degrading on-demand, these batteries could pave the way as a new class of recyclable batteries for the technology that we use every day.