University of California – San Diego researchers have developed an ultrasound-emitting device that brings lithium metal batteries, or LMBs, one step closer to commercial viability. Although the research team focused on LMBs, the device can be used in any battery, regardless of the chemistry.

Ultrasound emitting device designed at University of California – San Diego Jacobs School of Engineering. Image Credit: UCSD. Click image for the largest view.

The device that the researchers developed is an integral part of the battery and works by emitting ultrasound waves to create a circulating current in the electrolyte liquid found between the anode and cathode. This prevents the formation of lithium metal growths, called dendrites, during charging that lead to decreased performance and short circuits in LMBs.

The device is made from off-the-shelf smartphone components, which generate sound waves at extremely high frequencies – ranging from 100 million to 10 billion hertz. In phones, these devices are used mainly to filter the wireless cellular signal and identify and filter voice calls and data. The researchers used them instead to generate a flow within the battery’s electrolyte.

James Friend, a professor of mechanical and aerospace engineering at the Jacobs School of Engineering at UC San Diego and the study’s corresponding author said, “Advances in smartphone technology are truly what allowed us to use ultrasound to improve battery technology.”

Currently, LMBs have not been considered a viable option to power everything from electric vehicles to electronics because their lifespan is too short. But these batteries also have twice the capacity of today’s best lithium ion batteries. For example, lithium metal-powered electric vehicles would have twice the range of lithium ion powered vehicles, for the same battery weight.

The researchers showed that a lithium metal battery equipped with the device could be charged and discharged for 250 cycles and a lithium ion battery for more than 2000 cycles. The batteries were charged from zero to 100 percent in 10 minutes for each cycle.

Ping Liu, professor of nanoengineering at the Jacobs School and the paper’s other senior author said, “This work allows for fast-charging and high energy batteries all in one. It is exciting and effective.”

The team detailed their work in the journal Advanced Materials.

Most battery research efforts focus on finding the perfect chemistry to develop batteries that last longer and charge faster, Liu said. By contrast, the UC San Diego team sought to solve a fundamental issue: the fact that in traditional metal batteries, the electrolyte liquid between the cathode and anode is static. As a result, when the battery charges, the lithium ion in the electrolyte is depleted, making it more likely that lithium will deposit unevenly on the anode. This in turn causes the development of needle-like structures called dendrites that can grow unchecked from the anode towards the cathode, causing the battery to short circuit and even catch fire. Rapid charging speeds this phenomenon up.

By propagating ultrasound waves through the battery, the device causes the electrolyte to flow, replenishing the lithium in the electrolyte and making it more likely that the lithium will form uniform, dense deposits on the anode during charging.

The most difficult part of the process was designing the device, said An Huang, the paper’s first author and a Ph.D. student in materials science at UC San Diego. The challenge was working at extremely small scales, understanding the physical phenomena involved and finding an effective way to integrate the device inside the battery.

Haodong Liu, the paper’s co-author and a nanoengineering postdoctoral researcher at the Jacobs School said, “Our next step will be to integrate this technology into commercial lithium ion batteries.”

The technology has been licensed from UC San Diego by Matter Labs, a technology development firm based in Ventura, Calif. The license is not exclusive.

The work was funded by the U.S. Department of Energy and the Accelerating Innovation to Market team at UC San Diego. It is protected by patents: US#16/331,741 — “Acoustic wave based dendrite prevention for rechargeable batteries” and provisional# 2019-415 — “Chemistry-agnostic prevention of ion depletion and dendrite prevention in liquid electrolyte.”

Your humble writer would like to suggest this is a breakthrough at zero to 100% charging in 10 minutes. Should that be scaleable to commercial batteries the electric vehicle market will be very disrupted, indeed.

Perhaps even more interesting will be the application of this technology to other battery chemistries.

My heavens . . . 2000 charge cycles?


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