Florence Ansart

Advances in the recovering of spent lithium battery compounds

Advances in a process based on simple and environmentally compatible operations, aimed to the treatment and recycling of spent lithium-ion batteries, are reported in this paper. This process is safe, economic, and recovers as much of the battery materials as possible. It operates mainly in a selective dissolution in dilute acid, a chemical treatment of the filtrate and a thermal treatment of the solid residue. The validity of the process and its reproducibility have been evaluated at each step of the separation. This method involves very simple equipment and can be scaled-up for commercial production. Based on the projected quantities of lithium ion batteries available for recycling in the next few years, there is a significant market opportunity for a successful technology.

Powder synthesis of nanocrystalline ZrO2–8%Y2O3 via a polymerization route

Abstract A Pechini process has been used for preparation of yttria-stabilized zirconia gels and powders. Thermal behavior of gel and relationships between processing parameters and structure and microstructure of the powders have been determine to use this route for the preparation of thin film of YSZ. The thermal behavior of the gel has been studied by both thermogravimetric (DTA/TGA) and mass spectrometry analyses. The decomposition progress is in several steps and is based on a thermally induced anionic redox reaction. The transformation from amorphous powder (the gel) into a crystallized homogeneous oxide phase corresponds to an endothermic and two exothermic peaks in the DTA curve; the first one at 168°C is related to the evaporation of excess of ethylene glycol, the second peak at 300°C corresponds to a superposition of two reactions : the decomposition of some organics and the crystallization of YSZ. The last exothermic peaks correspond to the pyrolysis of organics residuals. A series of yttria-stabilized zirconia powders with different agglomerate structures have been synthesized by altering the acid citric–ethylene glycol ratio (CA/EG). The gel with CA/EG = 2.4 yields nanostructured powders at 325°C that is less porous and agglomerate with an average of 10–20 nm primary particles. Its specific surface area is around 55 m 2 /g.

Synthesis of YSZ powders by the sol-gel method: surfactant effects on the morphology

A colloid-emulsion route is established to prepare yttria stabilized zirconia (YSZ) powder, using cost-effective and commonly available inorganic salts as starting materials. Nanocrystalline, single-phase YSZ powders are prepared via calcinations of emulsion-derived precursor powder at 1000 °C for 2 hours. Formation of aggregates is detected, and the aggregates size and morphology depend on the chemical additives nature and milling. After chemical and mechanical treatments, the obtained powder has a spherical morphology, and the aggregates size is homogeneous and around 1 μm.

Study of the oxidation of aluminium nitride coatings at high temperature

Abstract Thin films of aluminium nitride have been deposited on silicon or alumina substrates by plasma enhanced chemical vapour deposition. The oxidation behavior of these coatings is studied and compared with the behavior of aluminium nitride thick films. We have analyzed the evolution of their optical properties at high temperature by laser spectrophotometry. The complementary characterization methods were high temperature X-ray diffractometry, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses. The oxidation of these coatings involves the formation of a solid solution of oxygen in the aluminium nitride in excess of 25 at.% up to a temperature of 900 °C, then of a biphasic AlN solid solution + alumina-α until the complete transformation into α-alumina at 1200 °C. The methods we have used underline a supplementary phenomenon of interaction with the substrate in the case of thin films on silicon. The results obtained led to a coherent presentation of the behavior of this material under oxidation.

New synthesis method of LiM1−xMx′O2 elaborated by soft chemistry for rechargeable batteries (M and M′ = Ni, Co or Mn)

Abstract Synthesis of LiCo1−xNixO2 by soft chemistry leads to a “new” material, which is more reactive and has a different morphology from oxide prepared by the direct solid-state method. The preparation of material by soft chemistry consists in a coprecipitation of powders, followed by a thermal treatment. This method allows a better control of structure, morphology and specific surface area (Sw). This one is directly linked to the manganese presence which can increase it by a factor 10. Concerning the morphology, the presence of manganese in sample leads to an oxide network favorable for a good lithium intercalation.

Investigation of Graded La2NiO4+δ Cathodes to Improve SOFC Electrochemical Performance

Mixed ionic and electronic conducting MIEC oxides are promising materials for use as cathodes in solid oxide fuel cells SOFCs due to their enhanced electrocatalytic activity compared with electronic conducting oxides. In this paper, the MIEC oxide La2NiO4+ was prepared by the sol-gel route. Graded cathodes were deposited onto yttria-stabilized zirconia YSZ pellets by dip-coating, and electrochemical impedance spectroscopy studies were performed to characterize the symmetrical cell performance. By adapting the slurries, cathode layers with different porosities and thicknesses were obtained. A ceria gadolinium oxide CGO barrier layer was introduced, avoiding insulating La2Zr2O7 phase formation and thus reducing resistance polarization of the cathode. A systematic correlation between microstructure, composition, and electrochemical performance of these cathodes has been performed. An improvement of the electrochemical performance has been demonstrated, and a reduction in the area specific resistance ASR by a factor of 4.5 has been achieved with a compact interlayer of La2NiO4+ between the dense electrolyte and the porous La2NiO4+ cathode layer. The lowest observed ASR of 0.11 cm2 at 800°C was obtained from a symmetrical cell composed of a YSZ electrolyte, a CGO interlayer, an intermediate compact La2NiO4+ layer, a porous La2NiO4+ electrode layer, and a current collection layer of platinum paste.

New chemical process for the preparation of fine powders and thin films of LSMx-YSZ composite oxides

Abstract Composite cathodes of La1−xSrxMnO3-yttria stabilized zirconia with various molar concentrations were deposited onto dense YSZ electrolytes by dip-coating technique. The dip-coated solution is original and is based on polymeric solution. Different ways were examined to prepare it. Pure composites are only obtained when the final polymeric solution is an emulsion between two intermediate polymeric solutions: in one solution, LaSrMn cations are present while the other one contains YZr cations. The cathode characteristics were then examined by scanning electron microscopy (SEM). Crack-free and homogeneous films are obtained. The porosity and the thickness of the film are a function of the molar ratio of YSZ in the composite film. Films with a porosity of about 30% are synthesized.

Catalytic coatings on steel for low-temperature propane prereforming to solid oxide fuel cell (SOFC) application

Catalyst layers (4-20 microm) of rhodium (1 wt%) supported on alumina, titania, and ceria-zirconia (Ce(0.5)Zr(0.5)O(2)) were coated on stainless-steel corrugated sheets by dip-coating in very stable colloidal dispersions of nanoparticles in water. Catalytic performances were studied for low-temperature (< or = 500 degrees C) steam reforming of propane at a steam to carbon ratio equal to 3 and low contact time (approximately 0.01 s). The best catalytic activity for propane steam reforming was observed for titania and ceria-zirconia supports for which propane conversion started at 250 degrees C and was more than three times better at 350 degrees C than conversion measured on alumina catalyst. For all catalysts a first-order kinetics was found with respect to propane at 500 degrees C. Addition of PEG 2000 in titania and ceria-zirconia sols eliminated the film cracking observed without additive with these supports. Besides, the PEG addition strongly expanded the porosity of the layers, so that full catalytic efficiency was maintained when the thickness of the ceria-zirconia and titania films was increased.

Prediction of thermal radiative properties (300–1000 K) of La2NiO4+δ ceramics

A multiscale numerical model is developed to predict the thermal radiative properties (TRP) of rough La2NiO4+δ coatings. The model integrates intrinsic and extrinsic contributions related to the chemical composition and the texture, respectively. High-temperature infrared reflectivity and thermogravimetric measurements on a La2NiO4+δ single crystal make it possible to understand the role of the excess oxygen in the intrinsic TRP. We show that dense ceramics with thicknesses higher than 4 μm are optically thick, and that one can adjust the surface roughness parameters to predict their TRP.

Erosion and High Temperature Oxidation Resistance of New Coatings Fabricated by a Sol-Gel Route for a TBC Application

This paper examines the erosion and cyclic oxidation performance of novel thermal barrier coatings produced via the sol-gel route. The ceramic top coat, with a thickness of 5-80 m, was deposited via a sol-gel route onto standard MCrAlY and PtAl bond coats. In both the erosion and the cyclic oxidation tests it was found that the bond coat had a profound affect on the results. The erosion of the sol-gel coatings were compared to standard EB PVD and PS TBCs and were found to be significantly higher. The effect of aging (100 h at 1100°C) on the erosion rates was also evaluated and was found to increase the erosion rates. The information obtained from the erosion and cyclic oxidation tests have highlighted the need to develop and optimise the parameters for producing thicker coatings