Lithium-ion batteries have high energy efficiency and good cycling life and are considered as one of the best energy storage device for hybrid and/or electrical vehicle. Still, several problems must be solved prior to a broad adoption by the automotive industry: energy density, safety and costs. To enhance both energy density and safety, the current study aims at depositing binder-free cathode materials using inductively-coupled thermal plasma. In a first step, lithium iron phosphate LiFePO 4 powders are synthesized in an inductively-coupled thermal plasma reactor and dispersed in a conventional polyvinylidene fluoride (PVDF) binder. Then, binder-free LiFePO 4 coatings are directly deposited onto nickel current collectors by solution precursor plasma spraying (SPPS). These plasma-derived cathodes (with and without PVDF binder) are assembled in button cells and tested. Under optimized plasma conditions, cyclic voltammetry shows that the electrochemical reversibility of plasma-derived cathodes is improved over that of conventional sol-gel derived LiFePO 4 cathodes. Further results related to the substitution of iron with manganese in the SPPS precursors (LiMPO4, where M = Fe or Mn) are discussed.

Lead-free piezoelectric materials are nowadays drawing considerable attention as lead titanium zirconium oxide (PZT) is considered “as a substance of very high concern” by the European Chemicals Agency because of its toxicity. An interesting PZT replacement material for high temperature capable ultrasonic transducers is bismuth titanate (Bi 4 Ti 3 O 12 ), which could be used for pipe thickness and corrosion monitoring in the oil & gas and nuclear industries. In this study, solution precursor plasma spraying (SPPS) is used to deposit Bi 4 Ti 3 O 12 coatings onto stainless steel substrates by means of inductively-coupled thermal plasma. The crystal structure and the morphology of the deposited coatings is studied as a function of the SPPS operating parameters such as plasma gases, electrical power, chamber pressure and spraying distance. SPPS of piezoelectric materials is an interesting one step process alternative to the time consuming layered-based chemical spray pyrolysis/calcination of sol-gel precursors.

Optical coherence tomography (OCT) is evaluated as a promising technique for microstructure characterization of plasma-sprayed ceramic coatings. OCT combines the principles of low coherence interferometry and optical heterodyne detection to obtain both a high sensitivity to weakly backscattered light and a high axial resolution. It can be used to accurately locate interfaces where the refractive index changes abruptly within translucent materials. In the present work, OCT cross-sectional images of thin yttria-stabilized zirconia (YSZ) coatings are considered. The interferograms forming the images are analyzed individually to successfully gather information related to light penetration depth inside coatings. The interferogram analysis allows the evaluation of the refractive index of the YSZ non-transformable tetragonal phase.