DAILY SCIENCE

Starting from scratch, researchers have built a battery with proteins instead of lithium
It is metal-free, it degrades on demand for recycling—and does an end-run around the ethical and environmental problems that plague lithium-ion
May 13, 2021

As the number of electric vehicles and smart gadgets surges, ethical and environmental problems with the lithium-ion batteries that power them is starting to loom large. Very few of the millions of batteries discarded each year get recycled. And mining the materials that make them can harm people and the environment.

A new biological battery could be the answer, say researchers from Texas A&M University who reported the technology in the journal Nature. The non-toxic batteries use no metals, and easy to degrade and recycle by being dissolved in an acidic solution.

Given the exploding growth of the battery market, the world will have some 15 million metric tons of discarded lithium-ion batteries to contend with by 2030, according to some estimates. And if business continues as usual, most of these will end up in landfills.

“The rate of recycling lithium-ion batteries right now is in the single digits,” said chemical engineering professor Jodie Lutkenhaus in a press release. “There is valuable material in the lithium-ion battery, but it’s very difficult and energy intensive to recover.”

Lutkenhaus, Karen Wooley and their colleagues have made an entirely new battery chemistry from scratch. They use polypeptides, which are components of proteins, to make the battery’s two electrodes, which pass electrons back and forth during charging and discharging.

The polypeptide electrodes remain stable during battery operation. But they degrade on demand when placed in acidic conditions to give amino acids and other building blocks, which can be recycled into new batteries. These degradation products are benign, so even if the batteries are tossed in a landfill or end up in the environment, they would dissolve harmlessly.

The new battery performs about one-third as well as a Li-ion battery. But its performance matches other metal-free batteries that have been made before using organic plastics. The issue with those organic batteries is that they are also difficult to recycle.

This is a first step, of course, but such a degradable polypeptide-based battery could address the need for green, sustainable batteries in a future circular economy, the researchers write.

Source: Tan P. Nguyen et al. Polypeptide organic radical batteries. Nature, 2021.

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