Iratxe de Meatza

Structural, magnetic and electrochemical study of a new active phase obtained by oxidation of a LiFePO4/C composite

In this work, a new phase produced by controlled oxidation of a LiFePO4/C composite has been isolated and characterized. This new compound preserves mainly an olivine structure, but the complete oxidation of Fe is implied. A significant iron mis-site disorder and vacancy formation is proposed. The new phase demonstrated possession of different spectroscopic, magnetic and electrochemical properties from triphilite–heterosite. AC and DC magnetic susceptibility and specific heat measurements showed that the new phase presented spin-glass behavior. Electrochemical cycling showed that the new phase reacted at 2.5 V, which is a different potential to the heterositeversus a Li anode. Moreover, it provoked reversion to the triphilite–heterosite system, although a fraction of the material remained as the oxidized phase.

Synthesis and characterisation of materials for solid oxide fuel cell cathodes

Solid Oxide Fuel Cells (SOFC) are one of the most promising future devices for energy production. New materials with better performance will be of crucial importance for their future development and commercialisation. This work summarises the basic operation principles of SOFCs and their material requirements. Samples of formula Gd0.7Sr0.3Mn0.8M0.2O3 (M = Cr, Ni) are used to show the research pathway followed for synthesis and characterisation of new materials as potential cathodes of SOFCs. Synthesis by sol-gel method and properties such as crystal structure, electrical conductivity and chemical compatibility with yttrium stabilised zirconia (8YSZ) electrolyte are discussed.

GREENLION Project: Advanced Manufacturing Processes for Low Cost Greener Li-Ion Batteries

GREENLION is a Large Scale Collaborative Project within the FP7 (GC.NMP.2011-1) leading to the manufacturing of greener and cheaper Li-Ion batteries for electric vehicle applications via the use of water soluble, fluorine-free, high thermally stable binders, which would eliminate the use of VOCs and reduce the cell assembly cost. The project has 6 key objectives: (i) development of new active and inactive battery materials viable for water processes (green chemistry); (ii) development of innovative processes (coating from aqueous slurries) capable of reducing electrode production cost and avoid environmental pollution; (iii) development of new assembly procedures (including laser cutting and high temperature pre-treatment) capable of substantially reduce the time and the cost of cell fabrication; (iv) lighter battery modules with easier disassembly through eco-designed bonding techniques; (v) waste reduction, which, by making use of the water solubility of the binder, allows the extensive recovery of the active and inactive battery materials; and (vi) development of automated process and construction of fully integrated battery module for electric vehicle applications with optimized electrodes, cells, and other ancillaries. Achievements during the first 18 months of the project, especially on materials development and water-based electrode fabrication are reported herein.

Nanostructure and Impedance Spectroscopy of Pr0.7Sr0.3Mn1-xMxO3 (M = Fe, Co, Ni; x = 0 and 0.2) Thin Films Grown by Pulsed Laser Deposition

Polycrystalline samples of Pr0.7Sr0.3MnO3 and Pr0.7Sr0.3Mn0.8M0.2O3 (M = Fe, Co, Ni), prepared by the citrategel process at 950 oC, have been deposited on yttria-stabilized zirconia (YSZ) single crystal substrates at 700 oC by pulsed laser deposition (PLD) for application to thin film solid oxide fuel cell cathodes. The structure of the polycrystalline powders prior to deposition was analyzed by X-ray powder diffraction (XRD) data. The XRD patterns were indexed having a single phase orthorhombic perovskite structure (Pbnm). The structure and composition of the films deposited by PLD were analyzed by X-ray Diffraction (XRD), X-ray fluorescence (XRF) and Scanning Electron Microscopy (SEM). All films are polycrystalline, maintaining the initial orthorhombic perovskite structure with a marked texture. The surfaces present pyramidal grains with different size distribution, showing a mean particle size of 80 nm. Electrochemical Impedance Spectroscopy (EIS) measurements were carried out on test cells of these materials. The Pr0.7Sr0.3MnO3 thin film presents an Area Specific Resistance (ASR) value of 25.63 ·cm at 850 oC while Fe, Co and Ni doped materials show resistances of 6.49, 2.42 and 5.12 ·cm, respectively.