Two-Dimensional "Hybrid Separator Membrane" Boosts Lithium Batteries' Lifespans
Designed to allow lithium ions to flow but prevent dendrites forming, this material could be key to longer-lasting, safer batteries.
Scientists at Friedrich Schiller University, Boston University, and Wayne State University have found a means to considerably boost the lifespan of rechargeable batteries — using a hybrid membrane to prevent dendrite formation.
Rechargeable batteries are undeniably useful, but while they're usable far more times than a standard alkaline battery they do come with a finite lifespan. As they're discharged and recharged, lithium dendrites form — tiny needle-like structures which eventually short-circuit the battery, piercing the separator membrane and potentially even starting a fire.
The solution, the scientists claim: A two-dimensional hybrid membrane, which allows the lithium ions to flow but prevents dendrites from forming. "That’s why we applied an extremely thin, two-dimensional membrane made of carbon to the separator, with the pores having a diameter of less than one nanometer," explains professor Andrey Turchanin of the team's work.
"These tiny openings are smaller than the critical nucleus size and thus prevent the nucleation that leads to the formation of dendrites. Instead of forming dendritic structures, the lithium is deposited on the anode as a smooth film."
"The key innovation here is stabilizing electrode/electrolyte interface with an ultra-thin membrane that does not alter current battery manufacturing process," adds associate professor Leela Mohana Reddy Arava. "Interface stability holds key in enhancing the performance and safety of an electrochemical system."
The team has applied for a patent on the technology, which will initially be used to boost the lifespan of lithium batteries used in electric vehicles and potentially the smaller batteries used in everyday electronics. The scientists have also indicated they're looking at applying the same concept to other battery types in the future.
In testing, at least, the concept appears to deliver: "To test our method, we recharged test batteries fitted with our Hybrid Separator Membrane over and over again," notes Antony George, Ph.D. "Even after hundreds of charging and discharging cycles, we couldn’t detect any dendritic growth."
The paper describing the team's work has been published under open-access terms in the journal Advanced Energy Materials.