Newly invented ultrasound device brings lithium metal batteries closer to viability

Researchers from the University California San Diego have developed a new ultrasound-emitting device that they say brings lithium metal batteries, known as LMBs, one step closer to commercial viability. The team says that while their research focused on using the ultrasound device with an LMB, it could be used in any battery regardless of the chemistry. The scientists say that the device is an integral part of the battery and works by emitting ultrasound waves to create a circulating current in the electrolyte liquid between the battery's anode and cathode.By continually circulating the electrolyte liquid, the device prevents the formation of lithium metal growths called dendrites during charging that lead to decreased performance and short-circuits in LMBs. The scientists say that the ultrasound device they created is made from off-the-shelf components and can generate sound waves at extremely high frequencies. The frequencies achieved are from 100 million to 10 billion hertz.

When similar devices are used in phones, they are mainly used to filter the wireless cellular signal and identify and filter voice calls and data. Researchers note that LMBs haven't been considered a viable option to power devices, ranging from electric vehicles to electronics, because the lifespan of the battery is too short. The batteries have twice the capacity of today's best lithium-ion batteries, making them very attractive for all manner of devices.

An LMB capable of operating an electric vehicle, for instance, would have twice the driving range of the lithium-ion powered vehicle. In testing, the team showed that the lithium metal battery equipped with the device could be charged and discharge for 250 cycles. A lithium-ion battery using the device could be charged more than 2000 cycles. The batteries recharge from zero to 100 percent in 10 minutes for each cycle.

The team notes that by propagating ultrasound waves through the battery, the device causes the electrolyte to flow, replenishing lithium in the electrolyte and improving the likelihood that lithium forms uniform, dense deposits on the anode during charging. The team says that the next step is to integrate its technology into a commercial lithium-ion battery.