There had been little success in developing garnet-based solid state batteries because the high impedance between the garnet electrolyte and electrode materials limited the flow of current, which decreases the battery's ability to charge and discharge.
Looking to solve the problem, the team inserted a thin layer of aluminium oxide between the lithium electrodes and the garnet, which is a solid non-flammable ceramic electrolyte. In this experiment, the layer of aluminium oxide is said to decrease the impedance 300 fold.
"This is an advancement in the field of solid state batteries – particularly in light of recent battery fires," said Liangbing Hu, associate professor of materials science and engineering, pictured. "Our garnet-based solid state battery solves the typical problems that trouble existing lithium-ion batteries: safety, performance, and cost."
In addition, the high stability of these garnet electrolytes enables the team to use metallic lithium anodes. Combined with high capacity sulphur cathodes, the technology is said to offer potentially unmatched energy density.