Atomic-level Transformations of Lithium Iron Phosphate as a Model Ceramic Material in Vacuum-Assisted Cold Spray Environment — 62p — Collin D. Rodmyre^†, Stephen Bierschenk^††, Paul Mack^†††, Desiderio Kovar††, and Alevtina Smirnova*^†,

^† Material Science and Engineering Program, South Dakota School of Mines, 501 E Saint Joseph St. Rapid City SD, 57701

^††Mechanical Engineering Department, University of Texas Austin, 204 E. Dean Keeton Street Austin, Texas 78712-1591

^†††Thermo Fisher Scientific, East Grinstead RH19 1UB, West Sussex, UK

* Chemistry, Biology, and Health Sciences Department, South Dakota School of Mines, 501 E Saint Joseph St. Rapid City SD, 57701

Cold spray (CS) technology is known as a fast and cost-effective method for surface coating and formation of dense layers from ductile particles, such as metals, metal alloys, or metal-based composites. However, this technology experiences significant challenges in engineering of ceramic coatings because of the ductile-free nature of ceramic particles.  A ceramic model compound, lithium iron phosphate, was chosen to study its ability for plastic deformation in a vacuum-assisted sub-/supersonic cold-spray environment at temperatures close to its melting point. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images demonstrate that ceramic particles after CS deposition undergoes plastic deformation and create a dense ceramic coating on a substrate surface. In-situ X-ray diffraction (XRD) analysis indicates that the model ceramic material exposed to CS in vacuum undergoes significant atomic-level transformations. The LFP particles become partially amorphous, and experience atomic-level transformations confirmed by significant shifts in binding energies for the corresponding elements (lithium, iron, phosphorous, and oxygen). Post-annealing and calendering of the deposited LFP ceramic layers increases materials crystallinity and its electrochemical performance tested in electrochemical cells with lithium metal anode.

South Dakota School of Mines & Technology
Alevtina Smirnova