Hydro-Québec

About: Hydro-Québec is a government organization based out in Montreal, Quebec, Canada. It is known for research contribution in the topics: Electric power system & Dielectric. The organization has 2596 authors who have published 4433 publications receiving 100878 citations.

Extraction of Layerwise Conductivities in Carbon-Enhanced, Multilayered LiFePO4 Cathodes

Abstract: We performed experimental studies to determine electronic properties of multilayered LiFePO 4 cathodes in order to quantify reductions in LiFePO 4 matrix resistivity and/or contact resistances between matrices and currentcollectors by addition of carbon black and graphite. In order to extract these layerwise and interlayer properties, we extended the Schumann-Gardner approach to analysis of a four-point probe experiment and solved the resulting coupled nonlinear equations numerically. We studied five cathodes with varying amounts (3-12 wt %) and types (carbon black, graphite) of conductive additives. LiFePO 4 particles within the electrodes were precoated with carbon before mixing with additives and binder. Experimental results showed reductions of ∼ 62% in electrical resistivities of LiFePO 4 matrix with addition of carbon black from 3 to 10 wt %; addition of graphite additives produced only small reductions. For concentrations above 6 wt % of conductive additives, homogeneous electronic resistivities were observed. Contact resistances at interfaces between LiFePO 4 matrix and carbon coating of current collector and between carbon coating and current collector were similar in all cases, indicating consistency in manufacturing. Future work will focus on combining models for capacitive loss with models for conductive properties, along with experimental verifications.

Catalytic activity and performance of LSM cathode materials in single chamber SOFC

Abstract: The catalytic activity of symmetrical LSM (La0.8Sr0.2MnO3) cells operated under single chamber solid oxide fuel cell (SC-SOFC) conditions was investigated for methane-to-oxygen ratios Rin between 1 and 2. The oxidation reactions over electrodes sintered at 1100 °C (LSM1100) and 1200 °C (LSM1200) were studied, and the effect of any combustion was followed through electrochemical impedance spectroscopy (EIS). The activity of the LSM1100 electrode increases with temperature. Above 700 °C, the conversion of the oxygen species may exceed 30%. As a consequence, oxygen depletion is occurring and a low frequency semicircle in the EIS spectra becomes predominant. An increase of the sintering temperature to 1200 °C leads to a decrease in the catalytic activity. A LSM1100 electrode deposited on a Julich half-cell proves to reach better performance at 600 °C than at 700 °C. On such complete cells, however, the catalytic combustion becomes much more complex than on a LSM cathode alone. We are thus proposing a comprehensive parameter, Rout, that is summarizing the processes inside the single chamber reactor.

Electrode materials having increased surface conductivity

Abstract: An electrode material, comprising complex oxide particles with a homogeneous conductive carbon-based material coating, is ne An electrode material, comprising a complex oxide of formula AaMmZzOoNnFf, in which A = an alkali metal, M = one or more transition metals and optionally a non-transition metal, Z = one or more non-metal and a, m, z, o, n and f are ≥ 0 and are chosen to provide electrical neutrality, has a homogeneous conductive carbon-based material coating to provide a regular electric field distribution at the material grain surfaces. Independent claims are also included for the following: (i) a process for carbon-based material deposition on the above electrode material by pyrolysis of a polymer (mixture), dispersed in the complex oxide, in vacuum or an inert gas atmosphere; (ii) a process for carbon-based materia deposition on the above electrode material by dismutation of carbon-based material monoxide, optionally mixed with an inert gas, below 900 degrees C optionally in the presence of a catalyst; (iii) a process for preparing the above electrode material by pyrolysis of an organic derivative of an alkali metal (A) to form a carbon-based material deposit on the complex oxide surface a to supply a portion of the alkali metal content of the complex oxide; and (iv) an electrochemical cell having one or more electr of the above electrode material.