A team of Brown University researchers has found a way to double the toughness of a ceramic material used to make solid-state lithium-ion batteries.
The researchers in the US infused a ceramic with graphene to increase the material’s fracture toughness in a bid to make a more robust lithium-ion battery electrolyte.
The solid electrolyte was made by mixing tiny platelets of graphene oxide with powder of a ceramic called LATP, and then heating the mixture to form a ceramic-graphene composite.
Mechanical testing of the composite showed a more than two-fold increase in toughness compared to the ceramic alone.
The strategy was described in the journal Matter.
The breakthrough could be useful in bringing solid-state batteries to the mass market by eradicating the issue of highly brittle ceramics fracturing during the manufacturing process.
Solid ceramic electrolytes are seen as a safer, non-flammable alternative to liquid electrolyte and can prevent the formation of lithium filaments, which could enable batteries to operate at higher currents.
Christos Athanasiou, a postdoctoral researcher in Brown’s School of Engineering, said: “What’s happening is that when cracks start in a material, the graphene platelets essentially hold the broken surfaces together so that more energy is required for the crack to run.”
The lead author of the research added: “There’s huge interest in replacing the liquid electrolytes in current batteries with ceramic materials because they’re safer and can provide higher energy density.
“So far, research on solid electrolytes has focused on optimising their chemical properties. With this work, we’re focusing on the mechanical properties, in the hope of making them safer and more practical for widespread use.
Athanasiou worked with Brown engineering professors Brian Sheldon and Nitin Padture, who have previously used nanomaterials to toughen ceramics for use in the aerospace industry.
Padture said: “You want the electrolyte to conduct ions, not electricity. Graphene is a good electrical conductor, so people may think we’re shooting ourselves in the foot by putting a conductor in our electrolyte. But if we keep the concentration low enough, we can keep the graphene from conducting, and we still get the structural benefit.”
The group plans to continue working to improve the material, trying nanomaterials other than graphene and different types of ceramic electrolyte.
Images: Research shows that graphene (rGO) can help prevent the propagation of cracks in ceramic materials used for battery electrolytes.
