A new soft, yet solid lithium battery electrolyte made from polymers and ceramics could help boost electric car battery capacity and lifespan.
The new battery electrolyte helps suppress the lithium “fingers” or dendrites that grow on a lithium battery anode over many discharge and recharge cycles, causing its lifespan to shorten and, if they reach the cathode, the battery to short circuit.
There has been much hope for solid state electrolytes to solve this problem, but to date no commercially viable product has yet come to market.
Now, the new research suggests another tack may solve the problem. Researchers from Berkeley University, in collaboration with Carnegie Mellon University (CMU) published details of research on the new electrolyte in Nature Materials.
They say that the soft, yet solid, electrolyte suppresses the early stages of dendrite formation, called “nucleation”, likening it to stopping the tiny cracks in your car’s windshield before they spread and break the glass.
The semisolid electrolyte can be used with lithium metal batteries, which can have as much as twice the energy capacity of today’s EV batteries but are especially vulnerable to lithium dendrites.
“Our dendrite-suppressing technology has exciting implications for the battery industry,” said co-author Brett Helms, a staff scientist in Berkeley Lab’s Molecular Foundry in a statement.
“With it, battery manufacturers can produce safer lithium metal batteries with both high energy density and a long cycle life.”
The researchers think that by using the semisolid electrolyte in lithium metal batteries, there could be a significant opportunity for not only electric cars, but also eVTOLs (electric vertical-take-off-and-landing air taxis), which have high energy demands and for which the need to lighten battery load is more important.
“While there are unique power requirements for EVs and eVTOLs, the PIM composite solid electrolyte technology appears to be versatile and enabling at high power,” said Helms.
However, according to an article in electronic engineering magazine IEEE, the cost of lithium metal batteries with semisolid electrolytes could be five-fold the price needed to bring electric car purchase costs on par with internal combustion engine vehicles.
Massachusett-based battery company SolidEnergy Systems says it is also chasing a semisolid electrolyte made of ceramics and polymers, and that it could be used in drones by the end of 2020.
But, as IEEE notes, “at $500 per kilowatt-hour, SolidEnergy’s battery is currently much pricier than conventional lithium-ion batteries,” but also notes that large-scale manufacturing may solve this issue.
Fu, C., Venturi, V., Kim, J. et al.
Universal chemomechanical design rules for solid-ion conductors to prevent dendrite formation in lithium metal batteries.
Nat. Mater. 19, 758–766 (2020).
Bridie Schmidt is lead reporter for The Driven, sister site of Renew Economy. She specialises in writing about new technology and has been writing about electric vehicles for two years. She has a keen interest in the role that zero emissions transport has to play in sustainability and is co-organiser of the Northern Rivers Electric Vehicle Forum.