Electrochemical pulses correct weakness in next-gen lithium metal batteries

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Two promising avenues in the development of next-energy storage involve the use of high-density lithium metal and a solid rather than liquid electrolyte, and a new study brings these branches of battery research together in an exciting new breakthrough. American scientists have demonstrated how the stability problems associated with these architectures could be solved using electrochemical pulses, paving the way for electric vehicles and smartphones that run much longer on each charge.

Part of this area of ​​research focuses on anodes, which act as one of the two electrodes in the device and help facilitate the transport of lithium ions through a liquid electrolyte. Today’s anodes are made from a mixture of graphite and copper, but pure lithium metal is an enticing alternative because it offers the highest energy density among solid materials. However, integrating lithium metal into batteries has proven difficult so far, with scientists running into a variety of safety issues that are quickly solving them.

There is a line of thought that using a solid electrolyte instead of a liquid would lead to a battery better suited for use with lithium metal. And this intersection of materials is at the center of new work by scientists at Oak Ridge National Laboratory (ORNL), who believe they’ve found a way to bring them together in a stable and durable way without compromising performance.

Melting materials in solid-state batteries is usually a delicate task, as the ongoing charge and discharge cycles lead to instability in the joints and cause voids to form, the so-called impedance of contact. Applying pressure is one way to fix this problem, but it is a technique that should be used periodically while the battery is running and can also cause a short circuit.

ORNL scientists have found that they can eliminate these voids by applying a short, high-voltage electrochemical pulse when the lithium metal anode is joined to a solid electrolyte. These pulses see a current flow around the voids which causes them to dissipate, resulting in more extensive contact at the materials interface.

Scientists have discovered a new way to improve contact between key layers in a solid-state battery

Andy Sproles/ORNL, US Department of Energy

Because it has no adverse effect on the battery and the pulse technique could be applied to restore it to nearly its original capacity, scientists imagine that this technology will one day offer a viable way to manage lithium-metal batteries. solid-state during operation. They say this type of system could offer twice the energy density of current solutions in a much smaller package, meaning electric vehicles can travel much farther per charge, or smartphones that run for days at a time. .

“This method will enable an all-solid-state architecture without applying extrinsic force that can damage the cell and is impractical to deploy during battery use,” said project co-lead Ilias Belharouak. “In the process we’ve developed, the battery can be made normally, and then a pulse can be applied to rejuvenate and refresh the interface if the battery becomes fatigued.”

Scientists are now continuing to develop the technology, experimenting with more advanced electrolytic materials, and investigating how it could be scaled up for use in a working-scale solid-state battery system.

The research was published in the journal ACS energy letters.

Source: Oak Ridge National Laboratory

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