Polymer dielectric film fuel cell does not have the manufacture method of catalyst-loaded electrode
Technical field
The present invention relates to a kind of polymer dielectric film fuel cell does not have the manufacture method of catalyst-loaded electrode.
Background technology
Polymer dielectric film fuel cell (polymer electrolyte membrane fuel cell, PEMFC) but have energy density and advantages such as power density is big, the low room temperature startup of working temperature, be considered to the optimal power supply of electric motor car and mobile electronic device.The core component of PEMFC is that (membrane electrode assembly, MEA), the quality of its structure is directly connected to the performance of battery to membrane electrode assembly.For the big electric current output of utilance, acquisition that improves catalyst, the electrode layer among the MEA should be thin as far as possible.Yet can obtain the PEMFC of enough big power output (as direct methanol fuel cell for need greater catalytic agent carrying capacity, direct methanol fuel cell, DMFC), reduce electrode layers thickness and have contradiction to a certain extent with the raising catalyst loading.
The catalyst that PEMFC uses normally is supported on platinum and the alloy thereof on the high-ratio surface charcoal.There are some researches show (L.Liu, et al, Electrochimica Acta, 1998,43,3657), if the catalyst that DMFC uses charcoal to carry, when catalyst loading is higher than 0.5mg/cm
2The time battery performance can't continue to improve; Do not have catalyst-loaded SC service ceiling and then can reach 8mg/cm
2In recent years, no catalyst-loaded quilt adopts more and more in the report of high-performance DMFC.
High dispersive no catalyst-loaded difficulty relatively in preparation, and in use take place easily to reunite and sintering.Make and do not have the key technology that catalyst-loaded electrode is acquisition high-performance DMFC efficiently.
Summary of the invention
The present invention is directed to the problems referred to above, propose the manufacture method that a kind of polymer dielectric film fuel cell does not have catalyst-loaded electrode.This method is simple to operate, and cost of manufacture is low, thereby suitable large-scale industrial production.
Technical scheme provided by the invention is: a kind of polymer dielectric film fuel cell does not have the manufacture method of catalyst-loaded electrode, and preparation earlier contains polymer dielectric and catalyst precarsor (as H
2PtCl
6, RuCl
3) solution; This kind solution is applied to substrate surface; After treating solvent evaporates, the catalyst precarsor in the substrate surface coating is reduced into metal.
Above-mentioned polymer dielectric is the strong-acid type polymer dielectric, or the strong base polymer dielectric; The solvent of above-mentioned solution is a water, or lower alcohol, or the mixture of lower alcohol and water (also can be the solvent of other solubilized catalyst precarsor and polymer dielectric); Above-mentioned substrate is heat-resisting chemically inert polymer film (as poly tetrafluoroethylene), or the polymer dielectric film of assemble use, or the diffusion layer material (as carbon paper) of assemble use; The above-mentioned method that catalyst precarsor in the substrate surface coating is reduced into metal is under the temperature that is no more than the polymer dielectric decomposition temperature, with substrate heat treatment under nitrogen atmosphere, make the catalyst precarsor in the substrate surface coating be reduced into metal: or substrate immersed contain in the concentrated solution of strong reductant, make the catalyst precarsor in the substrate surface coating be reduced into metal.
Advantage of the present invention is: making that will not have catalyst-loaded preparation and electrode combines, catalyst precarsor is reduced into metal under the protection of polymer dielectric, the catalyst granules that can prevent nano-scale takes place to reunite and sintering, obtains the catalyst of high degree of dispersion; Catalyst granules and the polymer dielectric that produces under this condition mixes simultaneously, can obtain the contact of fullest.These characteristics all are very beneficial for improving battery performance.Method provided by the invention is simple to operate, and cost of manufacture is low, thereby suitable large-scale industrial production.
Description of drawings
Fig. 1 is that no catalyst-loaded electrode of the present invention is made flow chart;
Fig. 2 supports the scanning electron micrograph of PtRu electrode surface for the nothing that makes with the present invention;
Fig. 3 supports the scanning electron micrograph of PtRu electrode section for the nothing that makes with the present invention;
Fig. 4 supports the X-ray diffraction spectrum that Pt and nothing support the PtRu electrode for the nothing that makes with the present invention.
Embodiment
Referring to Fig. 1, supporting the PtRu electrode with the making nothing is example, with H
2PtCl
6With RuCl
3(raw material A) is dissolved in ethanol or water, adds the ethanolic solution of an amount of perfluorinated sulfonic acid type polymer dielectric or polyvinyl pyridine quaternary ammonium type polymer dielectric (raw material B), and the ratio of Pt and Ru and polymer dielectric is regulated as required; According to the catalyst loading needs, this solution of certain volume is applied to poly tetrafluoroethylene or carbon paper surface (the ink coating surface that carbon paper is made into acetylene black and ptfe emulsion in advance, make its surfacing), poly tetrafluoroethylene or carbon paper place on the heating plate to promote solvent evaporates during operation; With the above-mentioned poly tetrafluoroethylene of catalyst precarsor and polymer dielectric or the NaBH that carbon paper immerses 2mol/L of scribbling
4Or N
2H
4The aqueous solution in, or 120 ℃ down with hydrogen reducings 1 hours, required nothing support the PtRu catalyst electrode.
Above-mentioned etoh solvent or water also can replace with the solvent of other solubilized catalyst precarsor and polymer dielectric.
The nothing that covers the carbon paper surface that adopts said method to make supports the surface and the section pattern of PtRu electrode and sees Fig. 2, Fig. 3, and catalyst layer surface is more smooth, thickness 10 μ m (every square centimeter contains 4mgPt+2mgRu) only.
Fig. 4 supports the X-ray diffraction spectrum that Pt (Fig. 4 c) and nothing support PtRu (Fig. 4 d) electrode with the nothing that covers the carbon paper surface that said method makes.Fig. 4 a, b are respectively perfluorinated sulfonic acid polymer dielectric film and the carbon paper X-ray diffraction spectrum of (surface coverage contains the diffusion layer of acetylene black and polytetrafluoroethylene) as reference object.The * peak is corresponding to the crystalline phase of fluorocarbon chain, from the polytetrafluoroethylene in perfluorinated sulfonic acid polymer dielectric film or the carbon paper among the figure; The # peak is from the graphite phase of carbon paper.Can calculate corresponding nothing according to the halfwidth of Scherrer formula Pt (220) diffraction maximum from Fig. 4 c, d supports the granularity that Pt catalyst and nothing support PtRu catalyst (the electrolytical content of perfluorinated sulfonic acid polymer is 15wt% in the electrode) and is respectively 6.1nm and 3.5nm.