A team at Rice University in the US has developed a technique for brushing metal powders onto anodes that prevents dendritic growth in a lithium-ion battery.
By using the brushing technique, the team says the metal powder adheres to the anode and becomes a thin, lithiated coating that effectively prevents the formation of dendrites.
The powder consisted of phosphorus and sulfur ground into the surface of a lithium metal foil.
The team said the powder at the lithium metal surface produced an artificial passivation layer that improved the stability throughout cycling by stabilising the metal surface.
Anodes modified in this way, and paired with lithium-iron-phosphate-oxide cathodes in cells, were tested over 340 charge-discharge cycles.
The study was published in the peer-reviewed journal Advanced Materials.
The university’s professor of materials science & nanoengineering, James Tour, said the technique would simplify the manufacturing of high-capacity batteries while greatly improving them.
He said: “Sanding these powdered solids into a lithium metal anode dramatically reduces dendrite formation that can short circuit a battery, as well as the accelerated consumption of the materials.”
Tour said the powders effectively tune the surface energy of the electrodes, making for a more uniform behaviour across the material.
He said: “This provides a metal composite surface that prevents the loss of lithium metal from the anode, a common problem in lithium metal batteries.
“Lithium metal batteries far exceed the capacity of traditional lithium-ion batteries, but the lithium metal is often difficult to repeatedly recharge.”
Testing a variety of powders
Lead author and Rice graduate student Weiyin Chen and his laboratory colleagues tested a variety of powder candidates on their electrodes.
They first brushed the surface to give it texture, then brushed in powder to create the fine film that reacts with the lithium metal and forms a solid passivation layer.
Chen and co-author Rodrigo Salvatierra, a former postdoctoral researcher and now an academic visitor in Tour’s laboratory, constructed test batteries and determined the treated anodes retained ultralow polarization for more than 4,000 hours, about eight times longer than bare lithium anodes.
The team also ground powder into a sodium electrode and discovered the process greatly stabilised its voltage overpotential.
Co-authors of the paper are Rice alums John Li and Duy Luong; graduate students Jacob Beckham, Nghi La and Jianan Xu, and academic visitor Victor Li. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of computer science and of materials science and nanoengineering at Rice.
The Air Force Office of Scientific Research (FA9550-19-1-0296) supported the research.