The design involves the direct application of a nanoporous polymer onto the lithium foil anode. The result is a battery that utilizes less lithium, provides greater energy per unit volume, has an extended lifespan, and is projected to cost half as much as lithium-ion batteries, researchers say.
Li-S batteries also have their limitations. Typically they contain a lithium anode (negative electrode) and sulphur cathode (positive electrode) with a separating layer. When the battery charges and discharges, large amounts of lithium and sulphur are reacted with one another, placing the lithium metal under a great deal of strain.
PhD student and lead researcher Declan McNamara of Monash Engineering said the thin polymer coating on lithium significantly improved the number of times the battery could be cycled.
“The polymer contains tiny holes less than a nanometre in size – one billionth of a metre – which allow lithium ions to move freely while blocking other chemicals that would attack the lithium. The coating also acts as a scaffold for lithium, and helps it charge and discharge repeatedly,” McNamara said.
“Metallic lithium is a bit of a double-edged sword. Lithium is packed full of energy, but in a bad battery, this energy is wasted on side reactions. On the other hand, if the energy is channelled correctly, it can make some incredible energy storage devices that are easier to make. This coating is a step towards highly efficient, easily manufactured Li-S batteries.”
The new design does not require nickel or cobalt, reducing its emission profile.