Ions Flow Reduction Increases Lithium-metal Batteries’ Efficiency

In a paper in Science Advances, Wan’s team prove that flowing ions near the cathode can potentially enhance the safety and lifespans of these next-generation rechargeable batteries.

Researchers led by Jiandi Wan, an associate professor in the Department of Chemical Engineering at the University of California, Davis, have proposed a potential solution to the growth of dendrites in rechargeable lithium-metal batteries. In a paper in Science Advances, Wan’s team prove that flowing ions near the cathode can potentially enhance the safety and lifespans of these next-generation rechargeable batteries.

Lithium-metal batteries use lithium metal as the anode. These batteries have a high charge density and potentially double the energy of conventional lithium-ion batteries, but safety is a big concern. When they charge, some ions are reduced to lithium metal at the cathode surface and form irregular, tree-like microstructures known as dendrites, which can eventually cause a short circuit or even an explosion.

Dendrite growth is caused by the competition between the mass transfer and reduction rate of lithium ions near the cathode surface. When the reduction rate of lithium ions is much faster than the mass transfer, it creates an electroneutral gap called the space-charged layer near the cathode, which contains no ions. The instability of this layer is thought to cause dendrite growth, so reducing or eliminating it might reduce dendrite growth and therefore extend the life of a battery.

Wan’s idea was to flow ions through the cathode in a microfluidic channel to restore a charge and offset this gap. In the paper, the team outlined their proof-of concept tests, finding that this flow of ions could reduce dendrite growth by up to 99%.

For Wan, this study is exciting because it shows the effectiveness of applying microfluidics to battery-related problems and paves the way for future research in this area. “With this fundamental study and microfluidic approaches, we were able to quantitatively understand the effect of flow on dendrite growth,” he said. “Not many groups have studied this yet.”

Though it is likely not possible to directly incorporate microfluidics in real batteries, Wan’s group is looking at alternative ways to apply the fundamental principles from this study and introduce local flows near the cathode surface to compensate cations and eliminate the space-charged layer.

“We are quite excited to explore the new applications of our study,” he said. “We are already working on design of the cathode surface to introduce convective flows.”

 

Originally Published by materialstoday

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