Toray Industries, Japan, has announced that it has created an ion-conductive polymer membrane for air batteries.
Employed in separators, this membrane should help improve the safety and longevity of lithium-air batteries and extend the cruising ranges of electric vehicles, industrial drones, and urban air mobility systems, Toray said in a release.
The company developed part of this technology under a grant for the JPN P21005 project of New Energy and Industrial Technology Development Organization.
Demand is surging for rechargeable batteries for electric vehicles and other automotive applications and mobile electronic devices, stationary storage batteries, and other consumer applications. These rechargeable batteries have to be lighter and deliver higher energy densities to increase the cruising ranges of electric vehicles and industrial drones and make urban air mobility systems feasible.
Lithium-air batteries employ air electrode at the anode and metallic lithium at the cathode, and have captured particular attention in this regard. That is because they are lighter than conventional lithium-ion batteries and offer a 10-fold higher theoretical specific energy density. The downside of using microporous film, a common separator, in these batteries is that different electrolytes used in the anode and cathode mix after repeated charge and discharge cycles. The batteries thus tend to deteriorate easily. Another issue is that lithium dendrite deposition and growth during charging can compromise safety by breaking through a separator and causing a short circuit between positive and negative electrodes.
Toray addressed these issues by designing a polymer that enables lithium-ion hopping and leveraging the molecular design technology for highly heat-resistant aramid polymers that it has cultivated over the years to create a lithium salt compound.
The result was a non-porous polymer membrane with an ion conductivity of 3×10-5S/cm. This high conductivity enables batteries to operate despite the membrane being non-porous. This non-porosity makes it possible, in principle, to attain two types of electrolyte separation and suppresses lithium dendrite formation.
Toray verified that lithium metal batteries employing its ion-conductive polymer film can operate stably 10 times longer during charge-discharge cycles than those using microporous film. The company will accelerate research and development to swiftly complete its new technology and deploy it with advanced rechargeable batteries, including for developing lithium-air batteries.
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