The device is constructed of smart phone components that are available off the shelf that produce sound waves with extremely high frequencies ranging between 100 million and 10 billion hertz. In smartphones, the devices are used mostly to block the wireless cellular signal and recognize and filter voice calls and data. Researchers employed them to produce a flow within the electrolyte of the battery. Image: David Baillot/University California San Diego’s
Invention will bring the lithium-metal batteries one step closer towards commercialization.
Researchers from the University of California San Diego University of California San Diego created an ultrasound emitting device that can bring lithium-metal batteries, also known as LMBs, just one step away from commercialization.
While the team of researchers was focused on LMBs, they can be used in any other battery regardless of the chemistry. The device the researchers designed is an integral part of the battery. It functions by emitting ultrasound waves that generate a circulating electric current in the electrolyte liquid between the cathode and anode. This helps prevent the development of growths in lithium metal, called dendrites, during charging, which can cause a decrease in effectiveness and degraded short circuits inside LMBs.
The device is built of smart phone components that are available off the shelf that generate sounds at very high frequencies ranging between 100 million and 10 billion hertz. In smartphones, the devices are used mostly to filter wireless cellular signals and to identify and filter calls to voice and data. Researchers have used them to produce a flow within the battery’s electrolyte.
“Advances in smartphone technology are truly what allowed us to use ultrasound to improve battery technology,” said James Friend, a professor of aerospace and mechanical engineering in the Jacobs School of Engineering at U.C. San Diego and the study’s co-author author.
The device researchers created is an integral component of the battery. It functions by emitting ultrasound waves that generate a circulating electric current in the electrolyte liquid between the cathode and anode. This helps prevent the development in the form of growths made from lithium, referred to as dendrites, that can cause a decline in effectiveness and short circuits in LMBs. Image Credit: David Baillot/University California San Diego
Currently, LMBs aren’t thought of as a feasible alternative for powering everything from electric vehicles to electronic equipment due to their life span being too small. They also offer twice the capacity of today’s most powerful lithium-ion batteries. For instance, electric vehicles powered by lithium metal will have twice the power of lithium ions, with the same weight as the battery.
Researchers discovered that a lithium-metal battery with this device could be recharged and charged for 250 cycles, and the lithium-ion battery can last more than 2000 cycles. They charged the batteries from 0 to 100 percent in just 10 hours for each cycle.
“This work allows for fast-charging and high energy batteries all in one,” said Ping Liu, professor of nanoengineering at the Jacobs School and the paper’s other lead author. “It is exciting and effective.”
The team’s work is described in the February 18th, 2020, online edition of Advanced Materials. Most batteries research initiatives are focused on finding the best chemical formula to make batteries with a longer lifespan and charge more quickly, Liu said. In contrast, this U.C. San Diego team sought to address a fundamental problem with the idea that the electrolyte fluid between the cathode and the anode is static in a traditional battery. When the battery is charged, the lithium-ion contained in the electrolyte depletes, increasing the likelihood that lithium will be distributed differently on the anode. This causes the formation of needle-like structures known as dendrites, which can expand unchecked from the anode toward the cathode. This can cause batteries to be short-circuited and even catch flames—the rapid charging speed speeds this issue up.
Researchers have demonstrated that a lithium-metal battery with this device could be recharged and charged for 250 cycles, and a lithium-ion battery can last more than 2000 cycles. The batteries were charged from 0 to 100 percent within 10 minutes each time. Credit: David Baillot/University of California San Diego
Propagating ultrasound signals through the battery triggers the flow of electrolytes and replenishes the lithium within the electrolyte. It makes it more probable that liquid will develop uniform solid deposits on the electrode during charging.
The most difficult aspect of the entire process was creating the device, according to An Huang, the paper’s initial author and Ph.D. graduate student studying the field of materials research from U.C. San Diego. The difficulty was working on tiny scales, comprehending the physical mechanisms involved, and coming up with a viable method to incorporate the device into the battery.
“Our next step will be to integrate this technology into commercial lithium-ion batteries,” said Haodong Liu, the paper’s co-author as well as a postdoctoral nanoengineering research fellow at Jacobs School.
The technology was granted a license through U.C. San Diego by Matter Labs, a technology development company with its headquarters within Ventura, California. The license does not mean that the technology is exclusive.
They are referred to as “Enabling rapid charging lithium metal batteries via surface acoustic wave-driven electrolyte flow” by An Huang, James Friend, Ping Liu, and Haodong Liu 18, 2020. Advanced Materials.
DOI: 10.1002/adma.201907516The work was funded by the U.S. Department of Energy and the Accelerating Innovation to the Market team at U.C. San Diego. Patents protect it: U.S. #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.”