CN1274046C - Method for producing proton exchange film fuel cell core module - Google Patents

Abstract

The invention provides a method for manufacturing the core component of a proton exchange membrane fuel cell. The method is characterized in that the precursor salt of the catalyst is chemically reduced in an aqueous solution of a sulfonic acid type anionic polymer with proton conductivity to obtain ion-modified nano-catalyst particles. , and then transfer the ion-modified nano-catalyst particles to the proton exchange membrane by brushing, inkjet printing or transfer printing; The method is transferred to the proton exchange membrane; or the cationic polymer is electrostatically self-assembled on the surface of the proton exchange membrane, and then the proton exchange membrane treated with the cationic polymer is immersed in the aqueous dispersion of the ion-modified nanocatalyst to self-assemble the ion-modified nanocatalyst. Thus, a core assembly for a proton exchange membrane fuel cell is obtained. Since the surface of the catalyst particles in the component is modified with a sulfonic acid type anionic polymer, it has good proton conductivity.

Description

A kind of manufacturing method of core component of proton exchange membrane fuel cell

technical field

The invention relates to a manufacturing method of a core component of a proton exchange membrane fuel cell, which is characterized in that the surface of nano catalyst particles in the catalytic layer is modified with a sulfonated anion polymer with proton conductivity.

Background technique

In today's global energy crisis and deteriorating environment, improving resource utilization and reducing environmental pollution has become an important subject of scientific research. As a clean energy technology, fuel cell technology has become one of the hot spots of international high-tech competition. The fuel cell core component (Catalyst coated membrane, CCM) is the core component of the proton exchange membrane fuel cell (PEMFC), which consists of a proton exchange membrane and a catalytic layer coated on both sides of the membrane. In some early patents or other reports at home and abroad, the combination of the membrane and the catalytic layer is generally formed by coating the catalyst on the gas diffusion electrode (such as porous carbon paper, carbon cloth), and then hot pressing with the proton exchange membrane. This kind of assembly was also called membrane electrode (membrane electrode assembly, MEA) in the early days. With the development of PEMFC technology, it is found that the components formed by coating the catalytic layer on the proton exchange membrane have better catalytic layer uniformity and gas-liquid-proton three-phase reaction channels, which can be achieved at a lower catalyst loading. Better output performance. Therefore, CCM has also become one of the mainstream trends and advanced fields of PEMFC. In CCM, due to the relatively fixed selection of materials for the proton membrane, perfluorosulfonic acid membranes with fully fluorinated main chains are generally used. The cost is high but the performance is stable. Therefore, the improvement of the cost and performance of CCM depends to a large extent on the catalytic layer structure.

US2004124091 describes a method for continuously preparing CCM. In their invention, one side of the proton exchange membrane is covered by a polymer back film, and the other side is formed by screen printing of Pt/C catalyst and ion exchange resin. After drying, remove the polymer backing film, and print the catalytic layer on the other side of the proton exchange membrane using the same method. US2004086632 describes a method that first heats the proton exchange membrane to above the glass transition temperature to soften the membrane surface, and then transfers the mixture of catalyst and ion exchange resin mixed in the fluidized bed to the surface of the proton exchange membrane to form CCM by means of blowing air . US6749892 describes a method of sputtering catalyst metal or carbon-supported catalyst onto the surface of a proton exchange membrane to form a CCM by means of arc sputtering.

It can be considered that the typical manufacturing method of the existing CCM is to prepare the Pt/C catalyst first, then mix the Pt/C catalyst with a proton-conducting resin (such as Nafion) and transfer it to the proton exchange membrane or gas diffusion electrode to form it. The conductive resin is not easy to be in close contact with the catalyst, and a large number of Pt catalysts are isolated in the micropores of porous carbon black, far away from the proton, electron, and gas three-phase channels necessary for catalytic reactions, and the efficiency is low, and its utilization rate is only 10%. ~20% [Electrochim.Acta, 2001, 46, 1657; J Mater.Res., 2004, 19, 2279]; for the CCM where the catalyst metal is directly transferred to the proton exchange membrane, due to the high surface Activity, the catalyst generally exists in the form of agglomerates or thin films, which reduces the surface active area of the catalyst.

Contents of the invention

The purpose of the present invention is to provide a new manufacturing method for the core component of a proton exchange membrane fuel cell. The manufacturing method constructs a more perfect proton conduction channel in the electrochemical reaction area of the catalytic layer of the fuel cell, that is, the surface of the catalyst particles, so that the catalytic The layer has in-situ conductivity, thereby reducing the ohmic polarization of the catalytic layer due to poor proton conduction.

The manufacturing method step of proton exchange membrane fuel cell core assembly of the present invention is:

Step 1: Prepare the dispersion of nano-catalyst particles modified by sulfonic acid type anionic polymer: take Nafion resin, or sulfonated polystyrene-polyethylene or butene-polystyrene, or sulfonated trifluorostyrene sulfonic acid type Dissolve the polymer in deionized water, add catalyst metal Pt or/and Pd or/and Ru precursor salt, add an alcohol reducing agent with a boiling point lower than 120°C and mix well, adjust the pH value to above 7 with NaOH, in nitrogen Heating to 70-95°C under protection, refluxing the mixed solution until the reaction of the precursor salt of the catalyst metal is completed, and obtaining a dispersion liquid with sulfonic acid-type anionic polymers on the surface of the nano-catalyst particles, the reaction conditions: sulfonic acid-type polymer monomer The molar ratio to the catalyst precursor ion is 1:0.5-15, the mass ratio of water to alcohol in the mixed solution is 1:0.7-10, the precursor salt of the catalyst metal Pt is H ₂ PtCl ₆ , the catalyst metal Pd The precursor salt of the catalyst metal Ru is PdCl ₃ , the precursor salt of the catalyst metal Ru is RuCl ₃ , and the alloy catalyst is a mixture of precursor salts of alloying elements according to the alloy dosage ratio;

Step 2: Purify and separate the dispersion of nano catalyst particles modified with sulfonic acid anionic polymer obtained in step 1: the separated pure sulfonic acid anionic polymer modified nano catalyst particles are directly applied to the proton exchange on the membrane; or use ethylene glycol to adjust the nano-catalyst particles modified by sulfonic acid anionic polymers into ink, and inkjet print them on the proton exchange membrane; or use ethylene glycol to adjust the nano-catalyst particles modified by sulfonic acid anionic polymers In the form of ink, the ink is transferred to the PTFE film by inkjet printing or brushing, and then transferred to the proton exchange membrane by hot pressing; or the cationic polymer is first self-assembled on the surface of the proton exchange membrane, and then its Immerse in the sulfonic acid type anionic polymer nano-catalyst particle dispersion obtained in step 1 for 24-48 hours to obtain the core assembly of the proton exchange membrane fuel cell.

The sulfonic acid type polymer is a branched chain with a sulfonate group, and the polymer does not contain anionic polymers that can ionize other groups in aqueous solution, which can be perfluorosulfonic acid resin, sulfonated trifluorobenzene Ethylene, polymethylphenylsulfonate siloxane, sulfonated polyether ether ketone, sulfonated polystyrene-polyethylene copolymer, sulfonated polystyrene-polyethylene/butylene-polystyrene.

The alcohol reducing agent with a boiling point lower than 120° C. refers to any one of methanol, ethanol, propanol and isopropanol.

The purification and separation of the nano-catalyst particle dispersion liquid modified by the sulfonic acid type anionic polymer is to use a semi-permeable membrane to filter out Na ⁺ , Cl ^- impurity ions.

The method for purifying and separating the nano-catalyst particle dispersion liquid modified by sulfonic acid anionic polymer is to add H ₂ SO ₄ to adjust the pH value to be less than 1, and centrifuge to separate the pure nano-catalyst modified by sulfonic acid anionic polymer.

The purification and separation of the nano-catalyst particle dispersion liquid modified by the sulfonic acid type anionic polymer is as follows: the pure nano-catalyst modified by the sulfonic acid type anionic polymer is phase-transferred by using chloroform non-polar solvent.

The method for self-assembling cationic polymers on the surface of the proton exchange membrane is: soak the proton exchange membrane in 5wt% H ₂ O ₂ , deionized water, 1mol/L H ₂ SO ₄ , and deionized water respectively After 30 minutes, soak in 0.05mol/L polydimethyldiallylammonium chloride solution for 1 to 3 hours, then soak in 1mol/L H ₂ SO ₄ and deionized water for 30 minutes each, that is A proton exchange membrane assembled with a cationic polymer was obtained.

Compared with the existing Pt/C fuel cell core components, the core component obtained by the present invention has good proton conductivity because the catalyst particles modify the sulfonic acid type anionic polymer, and the ohmic polarization formed by the proton conduction resistance of the catalytic layer Very small; Compared with the existing Pt sputtering or chemical deposition on the fuel cell core assembly on the proton exchange membrane, the core assembly of the present invention is coated with a sulfonic acid type anionic polymer due to the surface modification of the catalyst particles, and the catalyst particles are highly dispersed. It does not exist in the form of agglomeration, so it has good catalytic performance.

Detailed ways

The following examples are further illustrations of the present invention.

Example 1

Add 1mL _of 5wt% Nafion solution into 70mL deionized water, add 10mL of _H2PtCl2 solution with a concentration of 15g/L under mechanical stirring, add 60mL of absolute ethanol after 5min, and continue stirring for 10 minutes to adjust the pH value of the system with NaOH 12, seal the reaction vessel and pass _N2 protection, heat the reaction solution and reflux at 84 ° C for 10 minutes to obtain a dispersion of nano-catalyst particles modified by sulfonic acid anionic polymers, the zeta of the dispersion is -18mV, and the particle size is 1.9 ± 0.2nm. During the reflux process, NaOH was continuously added dropwise to keep the pH value of the system at 12.

Soak the proton exchange membrane in 5wt% H ₂ O ₂ , deionized water, 1mol/L H ₂ SO ₄ , and deionized water for 30 minutes, then put 0.05mol/L polydimethyldiallyl After soaking in ammonium chloride solution (PDDA) for 2 hours, then soaking in 1mol/L H ₂ SO ₄ and deionized water for 30 minutes respectively, a proton exchange membrane assembled with PDDA cations was obtained, and the proton exchange membrane was immersed in sulfur The nano-catalyst particle dispersion modified by the acid-type anionic polymer is electrostatically self-assembled for 36 hours to obtain a core component for a thin-layer proton exchange membrane fuel cell.

Example 2

Take 3wt% sulfonated polystyrene-polyethylene or butene-polystyrene solution 3mL and add it into 210mL deionized water, add _{24mL H2PtCl2} solution with a concentration of 15g/L under the condition of mechanical stirring, add 240mL iso Propanol, continue to stir for 10 minutes, adjust the pH value of the system to 9 with NaOH, seal the reaction vessel and pass _N2 protection, heat the reaction solution at 93 ° C for 16 minutes to obtain the dispersion of nano-Pt catalyst particles modified by sulfonic acid anionic polymer Liquid, the zeta of the dispersion is -14mV, and the particle size is 2.3±0.2nm. During the reflux process, NaOH was continuously added dropwise to keep the pH value of the system at 9. Adding 0.5 mol/L of H ₂ SO ₄ to the dispersion of nano catalyst particles to adjust the pH value to 0.5 and centrifuging, adding deionized water to the separated sulfonic acid anionic polymer-modified nano catalyst for washing and centrifuging. The cleaning process was repeated 3 times to obtain a pure sulfonic acid-type anionic polymer-modified nano-catalyst, and ethylene glycol was used to adjust the sulfonic-acid-type anionic polymer-modified nano-catalyst to form an ink, and the prepared ink was inkjet printed onto the polytetrafluoroethylene film superior.

Soak the proton exchange membrane in 5wt% H ₂ O ₂ , deionized water, 1mol/L H ₂ SO ₄ , and deionized water for 30 minutes each, and then place it together with the polytetrafluoroethylene film printed with catalyst ink. 2Mpa, 130°C hot pressing for 5 minutes to transfer the catalytic layer to the proton exchange membrane to obtain a core component for a thin-layer proton exchange membrane fuel cell.

Example 3

Add 3 mL of 3 wt% sulfonated trifluorostyrene solution into 210 mL of deionized water, add 12 mL of H ₂ PtCl ₂ solution with a concentration of 15 g/L and 12 mL of RuCl ₃ solution with a concentration of 2 g/L under mechanical stirring, and add 240mL of isopropanol, continue to stir for 10 minutes, adjust the pH of the system with NaOH to be 11, seal the reaction vessel and pass through _N Protection, heat the reaction solution and reflux at 93°C for 16 minutes to obtain nano-catalyst particles modified by sulfonic acid anionic polymer Dispersion liquid, the zeta of the dispersion liquid is -14mV, and the particle size is 4.3±0.3nm. During the reflux process, NaOH was continuously added dropwise to keep the pH value of the system at 11. Use chloroform non-polar solvent phase transfer to get pure sulfonic acid type anionic polymer modified nano-catalyst, add ethanol to the nano-catalyst modified by the separated sulfonic acid type anionic polymer and wash 3 times to obtain pure sulfonic acid type anion The polymer-modified nano-catalyst adopts ethylene glycol to adjust the sulfonic acid type anionic polymer-modified nano-catalyst into ink, and the prepared ink is ink-jet printed on the polytetrafluoroethylene film.

Soak the proton exchange membrane in 5wt% H ₂ O ₂ , deionized water, 1mol/L H ₂ SO ₄ , and deionized water for 30 minutes each, and then place it together with the polytetrafluoroethylene film printed with catalyst ink. 2Mpa, 130°C hot pressing for 5 minutes to transfer the catalytic layer to the proton exchange membrane to obtain a core component for a thin-layer proton exchange membrane fuel cell.

Claims (6)

1, the manufacture method of a proton exchange membrane fuel cell core module is characterized in that making step is:

The 1st step: the nanocatalyst particle dispersion that preparation sulfonic acid type anionic polymer is modified: get the Nafion resin; or sulfonated polystyrene-polyethylene or butylene-polystyrene; or sulfonation trifluorostyrene sulfonic acid-based polymer is dissolved in the deionized water; add catalyst metals Pt or/and Pd or/and the presoma salt of Ru; adding boiling point is lower than 120 ℃ alcohols reducing agent and fully mixes; regulate more than the pH value to 7 with NaOH; under nitrogen protection, be heated to 70～95 ℃; backflow mixed solution to the presoma reactant salt of catalyst metals finishes; obtain the dispersion liquid that the nanocatalyst particle surface is modified with the sulfonic acid type anionic polymer; its reaction condition: the mol ratio of sulfonic acid-based polymer monomer and catalyst precursor ion is 1: 0.5-15; water is 1 with the mass ratio of alcohol in the mixed solution: 0.7-10, the presoma salt of described catalyst metals Pt is H ₂PtCl ₆, the presoma salt of catalyst metals Pd is PdCl ₃, the presoma salt of catalyst metals Ru is RuCl ₃, alloy catalyst is the mixture of the presoma salt of alloying element by alloy dosage ratio;

The 2nd step: the finishing that step 1 is obtained has the nanocatalyst particle dispersion purification of sulfonic acid type anionic polymer to separate: the nanocatalyst particle that isolated pure sulfonic acid type anionic polymer is modified directly is brushed on the proton exchange membrane; The nanocatalyst particle that perhaps adopts ethylene glycol to regulate the modification of sulfonic acid type anionic polymer becomes the ink shape, and inkjet printing is on proton exchange membrane; The nanocatalyst particle that perhaps adopts ethylene glycol to regulate the modification of sulfonic acid type anionic polymer becomes the ink shape, adopts the method for inkjet printing or brushing to transfer on the polytetrafluoroethylene film ink, and hot pressing is transferred on the proton exchange membrane then; Perhaps earlier at proton exchange membrane surface self assembly cationic polymer, then it was immersed in the nanocatalyst particle dispersion that sulfonic acid type anionic polymer that step 1 obtains modifies 24-48 hour, obtain core components of PEMFC.

2, manufacture method as claimed in claim 1 is characterized in that described boiling point is lower than 120 ℃ alcohols reducing agent and is meant in methyl alcohol, ethanol, propyl alcohol and the isopropyl alcohol any.

3, manufacture method as claimed in claim 1, the purification separation that it is characterized in that the nanocatalyst particle dispersion of described sulfonic acid type anionic polymer is to adopt pellicle to filter out Na ⁺, Cl ^-Foreign ion.

4, manufacture method as claimed in claim 1 is characterized in that the method for purifying and separating of the nanocatalyst particle dispersion that described sulfonic acid type anionic polymer is modified is, adds H ₂SO ₄Regulate the pH value less than 1, and centrifugation goes out the nanocatalyst that pure sulfonic acid type anionic polymer is modified.

5, manufacture method as claimed in claim 1 is characterized in that the purification separation of the nanocatalyst particle dispersion that described sulfonic acid type anionic polymer is modified is: adopt the phase transfer of chloroform non-polar solven to go out the nanocatalyst that pure sulfonic acid type anionic polymer is modified.

6, manufacture method as claimed in claim 1 is characterized in that described method at proton exchange membrane surface self assembly cationic polymer is: with proton exchange membrane successively at the H of 5wt% ₂O ₂, deionized water, 1mol/L H ₂SO ₄, and deionized water in respectively soak 30 minutes after, the PDDA solution of putting into 0.05mol/L soaked 1～3 hour, then at the H of 1mol/L ₂SO ₄, respectively soaked the proton exchange membrane that promptly obtains having assembled cationic polymer 30 minutes in the deionized water.