In this publication, John Goodenough, one of the 2019 recipients for the Nobel Prize in Chemistry, and coauthors show a path to low-cost, high-capacity batteries with Lithium metal anodes by using graphene fluoride (GF) as a protective membrane that prevents dendrite formation on the anode. The membrane adheres to the Lithium metal through a sandwiched LiF layer. Full cells with these GF-LiF-Li anodes exhibited stable capacity for hundreds of cycles with both liquid and solid electrolytes, and even remain stable when exposed to a humid atmosphere. AFM images taken after 30 cycles show that the GF-LiF-Li anodes remains smooth while bare Li anodes have roughened surface consistent with nascent dendrite formation. PeakForce Tapping-enabled modulus measurements pinpoint the culprit. The SEI layer on bare Li is hard and breaks easily, while the protective layer on GF-LiF-Li anodes is soft and remains conforming to the surface during cycling.
It is exciting to see Bruker AFM technology contribute to such important research with the prospect of safer, higher density, and more affordable Lithium batteries.