Researchers at Washington State University have developed a protective layer for the lithium anode in a lithium metal battery, protecting the batteries from degradation and allowing them to work longer under typical conditions.
Lithium metal has the highest energy density but suffers from problems with lifetime and safety through the formation of dendrites in the battery. "If we can directly use lithium metal, we can improve the energy density of batteries dramatically," said Min-Kyu Song, assistant professor in the WSU School of Mechanical and Materials Engineering,
While lithium-ion batteries work by passing lithium ions between a graphite anode and a lithium cobalt oxide cathode, the anode in a lithium-metal battery is made of the high-energy lithium metal. To boost the performance of the lithium metal battery design, the team used selenium disulfide, a non-toxic chemical used in dandruff shampoo, in the porous carbon structure for their cathode. They added two additives to the liquid electrolytes that are typically explored in next-generation lithium batteries.
The two additives worked together to form a protective layer on the lithium metal surface that was dense, conductive, and robust enough to suppress the growth of dendrites while allowing good cycling stability, said Song. When tested at typical current densities people would use for electronics, the protected lithium metal anode was able to re-charge 500 times and retained high efficiency.
"Such a unique protective layer led to little morphological changes of the lithium anode over cycling and effectively mitigated the growth of lithium dendrites and unwanted side reactions," he said. "If commercialized, this novel formulation has real potential," he added. "Compared to solid-state batteries which are still years away, you don't have to change the manufacturing procedures, and this would be applicable to real industry much sooner, opening up a promising route toward the development of high-energy lithium metal batteries with a long cycle life."