Translated paperSolid electrolyte films in controlling their structures by electrophoretic deposition method☆
Graphical abstract
Formation of conduction paths by ordered array can enhance proton conduction.
Highlights
► We synthesized P2O5–SiO2 composite particles for proton conduction films. ► We made high proton conduction films in terms of electrophoretic deposition method. ► Structure of particle array can be controlled by the electric field.
Introduction
Exhaustion of fossil fuels and environment pollution become serious problems in contemporary society. Fuel cells are identified as an energy conversion system which directly changes chemical energy into electrical energy, and as clean energy supply system. Polymer electrolyte fuel cell is expected to develop for a use of cogeneration facility and a power source of electric cars [1]. For generation efficiency and Pt catalyst poisoning, the fuel cell is required to operate at intermediate temperature (373–573 K). However, some kinds of polymer electrolytes denature above 353 K. Then, inorganic materials, which are thermally and chemically stable, should be developed and were studied for application to the electrolytes at the intermediate temperature [2]. Especially, it was reported that P2O5–SiO2 particles indicated high proton conductivities. P2O5–SiO2 particle is made from the coating to the monodispersed SiO2 particle with the phosphorus oxide [3], [4]. It is necessary to make films by using P2O5–SiO2 particle for application to the fuel cell. The proton conductivity of the films is however very low in low humidity at temperature more than 373 K, and rising of the conductivity is required. It is important to form three-dimensional of proton conduction path with controlling of the pore size and the pore structure between particles in particulate films for improvement of the proton conductivity. Then, a particle assemble method by using electrophoretic deposition technique is useful for the speedy and mass production assembly [5], [6], [7]. What operation factor determined the structure of the film was not however understood. In this study, the influence of applied electric fields on the structures of particulate film in terms of the electrophoretic deposition method was examined. In addition, the relationship between the structures of the film and the proton conduction characteristic of the P2O5–SiO2 film was clarified.
Section snippets
Synthesis of SiO2 and P2O5–SiO2 sol
SiO2 sol was prepared by sol–gel technique (Stöber method). Ethanol including ammonia and distilled water were well stirred in a vessel. The ethanol solution was mixed with another ethanol solution including tetraethyl orthosilicate (TEOS). The reaction began in the mixture and was performed for 24 h in keeping at 323 K in a thermostat-bath. After 24 h reaction, the mixture became SiO2 sol for synthesis of particulate films by electrophoresis method. Control of SiO2 particle size was performed by
Monodispersed SiO2 sol
Preparation of TEOS, NH3 and H2O and geometric mean diameter and deviation of obtained SiO2 particles are tabulated in Table 1. The geometric mean diameter and deviation were estimated from FE-SEM images. Synthesized SiO2 particles in the sols have the geometric deviation of less than 1.1 and were monodispersed ones. Sampling of 1000 particles was done in this estimation. Then, it was confirmed that there was no difference of mean diameter between particle size distribution of 1000 particles
Conclusion
Electrophoresis and dielectrophoresis technique can possess the ability of synthesis of particulate film with high ordered array. Frequency control on AC bias leads for the ordered array and three-dimensional conduction path and utilization of composite particles with dissociation property results in synthesis of highly-conductive film.
Acknowledgments
This work was partially supported by Regional Innovation Cluster Program Global Type (Second Stage), Kyoto Environmental Nanotechnology Cluster, MEXT, Japan.
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Cited by (2)
Morphology control of amino acid particles in interfacial crystallization using inkjet nozzle
2014, Advanced Powder TechnologyCitation Excerpt :Colloids with precisely controlled spherical shape and highly uniform particle size distribution are also promising for manufacturing functional materials [5]. Thin films and composite particles have been fabricated by controlling the structure of ordered particles [6]. Bottom-up technology is often used for controlling particle properties in such fabrication processes.
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Japanese version published in JSPTJ, Vol. 46, No. 4 (2009); English version for APT received on July 19, 2011.