The technology of lithium-air batteries continues to move forward — with recent work by researchers from Mie University in Japan showing that one of the primary issues with the technology can be effectively addressed — improving the design, to limit the damage caused at the lithium/water interface, without decreasing the battery power.
Their new findings will be presented at the 247th National Meeting & Exposition of the American Chemical Society (ACS) in Dallas (March 16-20).
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For some background — lithium-air batteries hold great potential, some researchers have stated that these “breathing” batteries could potentially result in EVs with ranges greater than 300 miles a charge. There are, of course though, still some problems to resolve first, before the technology can enter commercial use.
“Lithium-air batteries are lightweight and deliver a large amount of electric energy,” explained Nobuyuki Imanishi, PhD “Many people expect them to one day be used in electric vehicles.”
The primary distinction between lithium-ion and lithium-air batteries is that lithium-air batteries replace the cathode with air — which results in a notably lighter battery, with the potential to hold in a great deal of energy.
The press release provides details on the new work:
One of the main components researchers are working on is the batteries’ electrolytes, materials that conduct electricity between the electrodes. There are currently four electrolyte designs, one of which involves water. The advantage of this “aqueous” design over the others is that it protects the lithium from interacting with gases in the atmosphere and enables fast reactions at the air electrode. The downside is that water in direct contact with lithium can damage it.
Seeing the potential of the aqueous version of the lithium-air battery, Imanishi’s team at Mie University in Japan tackled this issue. Adding a protective material to the lithium metal is one approach, but this typically decreases the battery power. So they developed a layered approach, sandwiching a polymer electrolyte with high conductivity and a solid electrolyte in between the lithium electrode and the watery solution. The result was a unit with the potential to pack almost twice the energy storage capacity, as measured in Watt hours per kilogram (Wh/kg), as a lithium-ion battery.
“Our system’s practical energy density is more than 300 Wh/kg,” Imanishi stated. “That’s in contrast to the energy density of a commercial lithium-ion battery, which is far lower, only around 150 Wh/kg.”
Altogether, this new unit shows a good deal of potential — high energy density, high conductivity of lithium ions, and the ability to be discharged and recharged 100 times, and relatively low costs. The remaining hurdle is power output, which is certainly very important, so it’s hard to say when exactly this technology will become commercially viable for use in EVs. Once it does though it could have a significant effect on the potential range of vehicles.