Tesis doctoral de Michael Lebert
The work presents the characterization of novel fuel cell electrodes based on swnts and platinum as the main constituents. The suitability of such swnt electrodes as an alternative for conventional fuel cell electrodes based on a-c has been confirmed by different spectroscopic and electrical measurements. Additionally, a new approach by aligned mwnts has been demonstrated which allows topologically more ordered/defined arrangements of catalyst layer and gas diffusion layer. The more ordered electrodes based on vertically aligned mwnts are expected to further improve fuel cell performance which has to be verified by forthcoming experiments, however. in comparison to conventional electrodes, the new swnt electrodes make use of only one carbon material and liquid state processing, thereby simplifying preparation. The advantages of pefcs with thin flexible electrodes, high current density and low weight, were combined with the enhanced operating temperatures of pafcs. Together with an unconventional electrolyte solution this enables a significantly mass- and volume-reduced fuel cell. The swnt-pafc fuel cell shows performance levels comparable to cells with long-term optimized commercial electrodes. The swnt electrodes are in the proof-of-concept status and further improvements should focus on the partial hydrophobization of the catalyst layer to reduce mass transport limitation by electrode flooding as well as on optimum size catalyst particle preparation. further progress will require the elimination of defects and other reaction products/impurities in cnts , production in high yield (to lower the actual high price of cnts with 500$/g 179 to decrease costs), and synthetic control of tube properties (diameter, length, chirality, number of concentric layers). Using a mass-oriented performance definition of fuel cells, e.G. W/g as proposed by gottesfeld and zawodzinski [77] would underline the advantages of swnt as electrode material. increased de-bundling of the swnts will help to enlarge the specific surface area, further reduce the electrode thickness and increase porosity. The high achieved conductivity values are not mandatory and may be sacrificed to longer tube length by using e.G. Moderate sonication (e.G. Us/sds). Future work should emphasize on longterm stability and optimization of the cathode.
Datos académicos de la tesis doctoral «Characterization of carbon nanotube gas diffusion electrodes in low temperature h2/o2 fuel cells«
- Título de la tesis: Characterization of carbon nanotube gas diffusion electrodes in low temperature h2/o2 fuel cells
- Autor: Michael Lebert
- Universidad: Autónoma de Madrid
- Fecha de lectura de la tesis: 16/04/2009
Dirección y tribunal
- Director de la tesis
- José Luis García Fierro
- Tribunal
- Presidente del tribunal: pilar Ocón esteban
- siegmar Roth (vocal)
- martti Kaempgen (vocal)
- Miguel Antonio Peña jimenez (vocal)