Lithium battery research points to safer, stronger, less flammable alternative
A new technique developed by University of Michigan Materials Science and Engineering professor Richard Laine’s research group holds promise for the quest to create a scalable solid-state alternative to traditional lithium-ion batteries. The work was recently published in the Journal of Power Sources.
Currently, solid-state ceramic alternatives to traditional lithium-ion batteries are complicated and expensive to produce, as well as difficult to scale to commercial production. The approach developed by Laine’s group, liquid-feed flame spray pyrolysis (LF-FSP), removes several energy and time intensive steps from the processing of the materials − an innovation that could prove vital as battery producers look for ways to bring solid-state battery production closer to a commercial reality.
Liquid-feed flame-spray pyrolysis eliminates the glass-forming, crushing and ball milling steps typical to the production of thin film ceramic components in solid-state batteries. Instead, they dissolve the film’s component materials into an alcohol solution, which the group combusts − rather spectacularly − in a designed and restrained jet engine. The resulting soot is processed to thin, dense films capable of conducting lithium ions. The group is now able to produce films as thin as 14 microns, about one seventh the thickness of a piece of copy paper. They are surprisingly flexible, with performance comparable to the flammable liquid electrolytes now used in lithium-ion batteries. Because they are ceramic rather than liquid, they offer the potential to produce batteries that will work and survive a wider array of temperatures and other stresses. The performance improves with temperature and due to its thermal stability, active cooling as used in current lithium ion batteries is unnecessary.
“With two billion lithium-ion battery cells produced every year, reducing the complexity of the production process, increasing the toughness and temperature range of operation of the product are key steps toward a commercially viable solid-state battery,” explained graduate student Eongyu Yi, the publication’s first author.
With high energy density and long lives, lithium-ion batteries have long dominated as the preferred battery source for mobile devices and laptop computers. Over the past decade they’ve become a popular choice for electric vehicle batteries as well. Though they’re widely used and longer-lived than conventional batteries, lithium-ion batteries have important limitations, including flammability and sensitivity to heat.
The type of lithium-ion batteries currently in popular use, including in electric vehicles, contain a flammable liquid electrolyte solution, usually a combination of lithium salts dissolved in a flammable, easily decomposed organic liquid which requires them to be operated at less than about 60 °C. The electrolyte solution shuttles ions between the anode and cathode to balance its charge.
For years, researchers have explored developing a durable, safe solid substance, usually a ceramic or a polymer, that could function as an alternative to the electrolyte solution. Solid ceramics, capable of safely expanding and contracting, are stable to much higher temperatures than liquid, allowing for a dramatically increased range of safe operating temperature.
The Laine group is currently working to push this line of inquiry further, attempting to produce even thinner films − a feat that would greatly improve batteries’ charge and discharge rates.
The group’s work is supported in part by Quallion Inc. of Sylmar, California, on a sub-contract from the U.S. Army’s Communications-Electronics Research, Development and Engineering Center (CERDEC), and in part by National Science Foundation’s Division of Materials Research- Ceramics.
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Read more about the Laine lab’s research.