Researchers at Australia’s Deakin University have reported a way of using common industrial polymers to create solid electrolytes for solid-state lithium-ion batteries.
The scientists’ new solid polymer electrolyte system, based on a new lithium transport mechanism, was weakly bonded to the lithium-ion to replace the liquid solvents typically used as electrolytes in battery cells.
Dr. Fangfang Chen and Dr. Xiaoen Wang from the university’s Institute for Frontier Materials published their study in the peer-reviewed journal Joule.
To date, they have conducted tests on a coin cell battery at 50 cycles at low charging rate (10 hours to full charge state), and plan to run them at temperatures above 60oC.
The team hasn’t calculated the energy density of their technology yet because they are focused on the polymer electrolytes, Wang told BEST.
He said: “Overall, our electrolyte material shows promising performance compared with other polymer systems, but there is still a lot of work to do to optimise the performance. The room temperature conductivity is not ideal compared with a liquid system.”
Inorganic electrolytes used in solid-state batteries include garnets, ceramics and perovskites, but almost all of them are brittle, which is a challenge when making thin and large area batteries (such as pouch cells) as the electrolyte can easily break.
“On the other hand, the solid polymer electrolytes are flexible,” Wang told BEST.
“We could make any size or shape according to different cell configurations. Another benefit is that the contact resistance between electrolyte/electrode will be improved in polymer systems.
“In the case of the inorganic system, the contact resistance between two inorganic layers is very high under traditional fabrication process.”
In addition to making batteries safer, the team believes the solid polymer electrolyte will allow batteries to work with a lithium metal anode, a bottleneck stopping electric vehicles, aircraft and portable electronics from developing at a faster pace.
Wang said this could be a way to double the energy density of lithium batteries, which, in commercial settings, are currently peaking at around 250Wh/kg (in Tesla’s Model 3 battery pack).
Getting that up toward 500Wh/kg would allow extended EV driving ranges, or smaller, cheaper and lighter battery packs. It’s not the 10X jump everyone seems to believe is coming down the pipeline, but it would be very significant, said Wang.
In the next edition of BEST we will be taking an in-depth look at solid-state batteries. To receive your print and/or digital copy sign up here.
