In-Situ Investigation of Lithium Dendrite Growth in Translucent Al-Containing Garnet, Li7−XLa3Zr2−XTaxO12 (LLZTO) Made By Pressure Filtration and Sintering

Abstract

Solid-state lithium-ion batteries (LIBs) are of interest, as they eliminate the need for flammable organic electrolytes. Dendrite growth has been identified as a big problem in solid-state LIBs that can lead to shorting during charging or can limit the rate of charging. The mechanism of the lithium dendrite growth needs to be studied in order to enhance the safety reliability of the solid-state LIBs. To visualize lithium dendrites in-situ, a translucent garnet-type oxide ceramic lithium-ion conductor with Ta as dopant, Li6.75La3Zr1.75Ta0.25O12 (LLZTO) was synthesized by pressure filtration and sintering. The lithium dendrite growth experiment was performed in an argon-filled glove box, and the LLZTO disk was put under a microscope. A lithium wire and a silver wire were put on the surface of the Al-LLZTO disk, and a voltage generator was used to connect them together. A constant DC voltage was applied, and the voltage and current across the two wires were measured. In-situ lithium dendrite growth was observed, and sharp images of the dendrites were captured by a camera. Also it was found that the voltage across the two wires was kept decreasing, while the current across the two wires kept increasing. This indicates that the resistance across the two wires was decreasing during the lithium dendrite growing process. A transparent tube furnace was built to investigate the lithium dendrite growth at different temperatures up to 200oC. The effect of temperature on dendrite growth will be presented and discussed.