Graphene oxide nanosheets could help to commercialise Li-metal batteries

1 min read

Lithium-metal batteries can hold up to 10 times more charge than lithium-ion batteries but haven’t been commercialised because of a fatal flaw: as they charge and discharge, lithium is deposited unevenly on the electrodes. According to researchers from the University of Illinois at Chicago, this means battery life is too short to make them viable, adding the batteries could also short-circuit and catch fire.

However, the team says it has developed a solution in the form of a graphene-oxide coated ‘nanosheet’ that, when placed in between the two electrodes of a lithium-metal battery, prevents uneven plating and allows the battery to function safely for hundreds of charge/discharge cycles. “Our findings demonstrate that 2D materials — in this case, graphene oxide — can help regulate lithium deposition in such a way that extends the life of lithium-metal batteries,” said associate professor Reza Shahbazian-Yassar, pictured.

In lithium-ion batteries, a separator is placed in the electrolyte. Usually made of a porous polymer or glass ceramic fibres, the separator allows lithium ions to flow through while keeping the other components blocked to prevent electrical shorts, which can lead to fires.

Shahbazian-Yassar and his colleagues used a modified separator in a lithium-metal battery in order to modulate the flow of lithium ions and control the rate of lithium deposition. They also coated a fibreglass separator with graphene oxide, producing a nanosheet.

Using a range of imaging techniques, the researchers showed that when the nanosheet was used in a lithium-metal battery, a uniform film of lithium formed on the anode’s surface, improving battery function and safety. “The nanosheet slows the passage of lithium ions enough to allow for more uniform plating on lithium ions across the surface of the electrode, which helps preserve battery life,” said Shahbazian-Yassar.

Computer models are said to have shown that graphene oxide can also suppress the growth of lithium dendrites mechanically. “We show that 2D graphene oxide materials are able to impede the formation of dendrites by changing the rate of lithium-ion diffusion through the graphene oxide layers,” Shahbazian-Yassar concluded. “This method has very high potential for industrial application and scalability.”