Investigating Connectivity, Cathode Electrolyte Interphase Formation & Composition in Transition Metal Fluoride Solid State Batteries via Pt

The development of high-energy and low-cost cathode materials is one of the most pressing issues in solid-state and Li–ion battery research. Transition metal fluoride conversion-type cathodes, such as CuF2, are an attractive alternative to state-of-the-art intercalation cathodes in this context, offering a three- to five-fold higher theoretical capacity at lower cost and in the absence of scarce metals. Lithium diffusivity and electrolyte instability concerns, as well as a limited knowledge of the growing cathode solid electrolyte interphase (CEI), have so far prevented their more practical pursuit. Here, using ex-situ Ptychographic and XRF Nanotomography, we would like to investigate a nanostructured CuF2 composite cathode, utilized in a solid-state battery (SSB). Tomograms provide a 3D model of the cathode layer spatial arrangement, component connectivity, their evolution, alongside a first insight into the local CEI composition and how it determines battery performance.