阅读说明：本技术 包括纳米纤维纺丝层的燃料电池用电解质膜 (Electrolyte membrane for fuel cell comprising nanofiber spun layer ) 是由 朴基镐 金夫坤 朴宗洙 于 2018-06-26 设计创作，主要内容包括：本发明涉及一种包括碳纳米纤维纺丝层的燃料电池用电解质膜、包括该电解质膜的燃料电池用膜电极组件和包括该膜电极组件的燃料电池。(The present invention relates to an electrolyte membrane for a fuel cell including a carbon nanofiber spun layer, a membrane-electrode assembly for a fuel cell including the electrolyte membrane, and a fuel cell including the membrane-electrode assembly.)

1. An electrolyte membrane for a fuel cell, comprising a nanofiber spinning layer, wherein the nanofiber spinning layer is formed by electrospinning a polymer composition.

2. The electrolyte membrane for a fuel cell according to claim 1, wherein the electrospinning filament is applied with a voltage of 30 to 70 kV.

3. The electrolyte membrane for a fuel cell according to claim 1, wherein the electrospinning is performed at a temperature of 40 to 80 ℃.

4. A membrane electrode assembly for a fuel cell, comprising:

an electrolyte membrane; and

an anode electrode and a cathode electrode disposed opposite to each other with the electrolyte membrane interposed therebetween,

wherein the anode electrode and the cathode electrode include a gas diffusion layer and a catalyst layer,

the electrolyte membrane is the gas diffusion layer for a fuel cell according to any one of claims 1 to 3.

5. A fuel cell, comprising:

a stack comprising one or more membrane electrode assemblies according to claim 4 and a separator interposed between the membrane electrode assemblies;

a fuel supply portion that supplies fuel to the stack; and

an oxidant supply portion that supplies an oxidant to the stack.

Technical Field

The present invention relates to an electrolyte membrane for a fuel cell including a nanofiber yarn layer, a membrane-electrode assembly including the electrolyte membrane, and a fuel cell including the membrane-electrode assembly.

The present application claims priority of korean patent application No. 10-2017-0080431, filed by 26.6.2017 to the korean intellectual property office, the entire contents of which are included in the present specification.

Background

Fuel cells (Fuel cells) are cells that directly convert chemical energy generated by oxidation of a Fuel into electrical energy, and in recent years, many studies have been made on Fuel cells, solar cells, and the like in order to overcome problems such as exhaustion of fossil fuels, greenhouse effect due to generation of carbon dioxide, global warming, and the like.

Generally, a fuel cell converts chemical energy into electrical energy using oxidation and reduction reactions of hydrogen and oxygen. In the anode (anode), hydrogen is oxidized and separated into hydrogen ions and electrons, and the hydrogen ions move to the cathode (cathode) through an electrolyte (electrolyte). At this time, the electrons move to the cathode through the circuit. The cathode undergoes a reduction reaction in which hydrogen ions, electrons and oxygen react to form water.

The electrolyte membrane is located between the cathode and the anode, and functions as a carrier of hydrogen ions while preventing contact between oxygen and hydrogen. Therefore, the electrolyte membrane of the fuel cell is required to have high hydrogen ion conductivity, and high mechanical stability and chemical stability are required.

Disclosure of Invention

Technical problem to be solved

An object of the present invention is to provide an electrolyte membrane for a fuel cell, which has a uniform pore distribution and high porosity and has excellent heat transfer efficiency, thereby exhibiting excellent power generation efficiency, a membrane-electrode assembly including the electrolyte membrane, and a fuel cell including the membrane-electrode assembly.

Technical scheme

The invention provides an electrolyte membrane for a fuel cell.

Further, the present invention provides a membrane electrode assembly for a fuel cell, comprising: the electrolyte membrane; and an anode electrode and a cathode electrode disposed opposite to each other with the electrolyte membrane interposed therebetween, wherein the anode electrode and the cathode electrode include a gas diffusion layer and a catalyst layer.

Further, the present invention provides a fuel cell comprising: a stack including one or more than two of the membrane electrode assemblies and a separator interposed between the membrane electrode assemblies; a fuel supply portion that supplies fuel to the stack; and an oxidant supply portion that supplies an oxidant to the stack.

Advantageous effects

The electrolyte membrane of the present invention has a high porosity and a uniform pore distribution, and thus is excellent in heat transfer efficiency, maintains the water content of the electrolyte membrane at an appropriate level, and a membrane electrode assembly and a fuel cell including the electrolyte membrane exhibit excellent power generation efficiency.

In addition, the electrolyte membrane of the present invention has excellent mechanical and chemical stability because it does not have a conductive nanofiber spinning layer without undergoing a carbonization process such as a heat treatment.

Drawings

Fig. 1 is an image showing the fine structure of the nanofiber spun layer manufactured in manufacturing example 1, which was photographed by a field emission scanning electron microscope device in experimental example 1, and the magnification thereof was 10 k.

Fig. 2 is an image showing the fine structure of the electrolyte membrane manufactured in comparative example 1-1, which was photographed with a field emission scanning electron microscope device in experimental example 1, and the magnification thereof was 10 k.

Fig. 3 is a graph showing current-voltage values measured in test example 2 for each unit cell of examples 1-2 to 4-2 and expressed as a current-voltage curve.

Detailed Description

Next, the electrolyte membrane for a fuel cell of the present invention will be described.

The electrolyte membrane for a fuel cell of the present invention includes a nanofiber spinning layer.

The nanofiber spun layer of the present invention is formed by electrospinning a polymer composition.

In one embodiment of the present invention, in the electrospinning, a voltage of 30 to 70kV, more preferably 40 to 60kV is applied to the polymer composition. When the voltage is less than 30kV, active fiber splitting (Split) cannot be achieved and the volatility of the solvent is reduced, and when the voltage exceeds 70kV, a clogging phenomenon (tip failure) occurs at the tip of the nozzle through which the polymer composition is spun.

In one embodiment of the invention, the electrospinning is carried out at a temperature of 40 to 80 ℃, preferably at a temperature of 50 to 80 ℃. When the temperature for electrospinning is lower than 40 ℃, the viscosity of the polymer solution becomes high, and the spinning cannot be smoothly performed, which results in failure to ensure mass productivity. On the other hand, when the temperature at which the electrospinning is performed exceeds 80 ℃, the solvent in the polymer solution is volatilized, so that the composition of the polymer solution is changed, and the internal pressure of the solution tank is increased due to the volatilization of the solvent, and thus there is also a risk of causing explosion.

In one embodiment of the present invention, the nanofiber spinning layer after electrospinning has an average fiber diameter of 0.01 to 2 μm, more preferably 0.02 to 1 μm. When the average fiber diameter is less than 0.01 μm, the size of the voids between the fibers decreases, resulting in a decrease in gas permeability, and when the average fiber diameter exceeds 2 μm, the size of the voids between the fibers increases, so that foreign matter present in the gas passes between the voids and accumulates in the cell stack, and thus the performance of the electrolyte membrane as a fuel cell decreases when evaluating the characteristics of the fuel cell.

In one embodiment of the present invention, the electrospinning is performed by applying pressure to a container storing the polymer composition in a state where a voltage is applied between a tip of an open part of the container and a current collecting plate spaced apart from the tip in a gravity direction, to perform jetting.

In one embodiment of the present invention, the tip is spaced apart from the current collecting plate by a distance of 10 to 20cm, preferably 12 to 16 cm. When the separation distance is less than 10cm, residual solvent remains, and due to the residual solvent, a melting (melting) phenomenon of the nanofibers occurs, resulting in deformation of desired nanofibers, and when the separation distance exceeds 20cm, the formation of the magnetic field between the current collecting plates is unstable, failing to form a nanofiber layer.

In one embodiment of the present invention, the polymer composition is a polyacrylic resin selected from the group consisting of polymethyl methacrylate (PMMA), Polystyrene (PS), polyacrylic acid (PAA), Polyacrylonitrile (PAN), and the like; polyvinyl chloride (PVC), Polyvinyl alcohol (PVA), Polyvinyl acetate (PVAc), and other polyethylene resins; polyester resins such as polyethylene Terephthalate (PET), Polytrimethylene Terephthalate (PTT), and Polybutylene Terephthalate (PBT); polyamide fibers (Nylon); polycarbonate (Polycarbonate), Polyethylene oxide (PEO); polyurethane (PU), Polyvinylidene fluoride (PVdF); polyvinylidene fluoride-hexafluoropropylene copolymer [ poly (vinylidine fluoride) -co- (hexafluoropropylene), P (VDF-HFP) ]; polyvinylidene fluoride-chlorotrifluoroethylene copolymer [ Poly (vinylidene fluoride) -co- (chlorotrifluoroethylene), P (VDF-CTFE) ], polytetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (Poly (tetrafluoroethylene-co-hexafluoropropylene-co-vinylidene fluoride, THV); polyetheretherketone (Poly ether ketone), polyphenylene oxide (PPO); polyphenylene Sulfone (PPS); polysulfone (Poly sulfone, PS); polyethersulfone (Poly ether sulfone, PES); polyimide (Polyimide, PI); polyetherimide (PEI); polyamideimide (PAI); polybenzimidazole (PBI); polybenzoxazole (PBO); and polyaramid (Poly amide).

In one embodiment of the present invention, the thickness of the nanofiber spinning layer is 20 to 200 μm, and more preferably 50 to 150 μm. When the thickness of the nanofiber spin layer is less than 20 μm, a decrease in physical properties occurs upon heat treatment, and when the thickness of the nanofiber spin layer exceeds 200 μm, the number of membrane-electrode assemblies of gas separation layers after heat treatment is limited.

Next, a method for producing the electrolyte membrane for a fuel cell of the present invention will be described. The above description of the electrolyte membrane for a fuel cell can be applied to the following method for producing an electrolyte membrane for a fuel cell unless otherwise specified.

The method for manufacturing an electrolyte membrane for a fuel cell according to the present invention includes: and a step of electrospinning the polymer composition to form a nanofiber spun layer.

The step of forming a nanofiber spinning layer comprises: and (b) applying a voltage of 30 to 70kV, more preferably 40 to 60kV, when the polymer composition is spun.

In one embodiment of the present invention, the electrospinning step comprises: and applying pressure to the container to perform spraying in a state where a voltage is applied between a tip of an opening portion of the container storing the polymer composition and a current collecting plate spaced apart from the tip in a gravity direction.

Next, the membrane electrode assembly for a fuel cell of the present invention will be explained.

The membrane electrode assembly for a fuel cell of the present invention comprises: the electrolyte membrane for a fuel cell; and an anode electrode and a cathode electrode disposed opposite to each other with the electrolyte membrane interposed therebetween.

In one embodiment of the present invention, the electrolyte membrane may be a perfluorosulfonic acid polymer, a hydrocarbon polymer, a polyimide, polyvinylidene fluoride, polyethersulfone, polyphenylene sulfide, polyphenylene ether, polyphosphazene, polyethylene naphthalate, polyester, doped polybenzimidazole, polyetherketone, polysulfone, an acid or a base thereof.

The anode electrode and the cathode electrode of the present invention respectively include a gas diffusion layer and a catalyst layer.

In one embodiment of the present invention, the catalyst layer of the anode electrode includes one or more catalysts selected from the group consisting of platinum, ruthenium, osmium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy, and platinum-transition metal alloy.

In one embodiment of the present invention, the catalyst layer of the cathode electrode includes platinum.

In one embodiment of the present invention, the catalyst of the anode electrode or the cathode electrode is supported on a carbon-based support.

Next, the fuel cell of the present invention will be explained.

The fuel cell of the present invention includes: a stack including the membrane electrode assemblies and separators interposed between the membrane electrode assemblies; a fuel supply portion that supplies fuel to the stack; and an oxidant supply portion that supplies an oxidant to the stack.

The separator of the present invention functions to prevent electrical connection between membrane electrode assemblies and to deliver fuel and oxidant supplied from the outside to the membrane electrode assemblies, and functions as a conductor connecting the anode electrode and the cathode electrode in series.

The fuel supply portion of the present invention functions to supply fuel to the stack, and the fuel supply portion may include: a fuel tank for storing fuel; and a pump that supplies the fuel stored in the fuel tank to the stack.

In one embodiment of the invention, the fuel is a gaseous or liquid hydrogen or hydrocarbon fuel.

In one embodiment of the invention, the hydrocarbon fuel is methanol, ethanol, propanol, butanol or natural gas.

The oxidizer supplying part of the present invention functions to supply an oxidizer to the stack.

In one embodiment of the invention, the oxidant is oxygen or air.

In one embodiment of the invention, the oxidant is injected by a pump.

In one embodiment of the present invention, the fuel cell is a polymer electrolyte type fuel cell or a direct methanol type fuel cell.

The present invention will be described in more detail below with reference to examples. However, the following examples are only for specifically illustrating the present invention, and the scope of the present invention is not limited to the following examples.

< production example 1> production of nanofiber spun layer

A polymer spinning solution (concentration: 20% by weight) was prepared by dissolving 200g of polyvinylidene fluoride (PVDF) in 800g of dimethylacetamide (DMAc).

After that, 6ml of the prepared polymer spinning solution was injected into a polymer composition supply container of an electrospinning apparatus manufactured by OSUNG TECH, and then a distance between a tip as an open part of the supply container and a current collecting plate spaced from the tip in a gravity direction was maintained at 15cm, and a voltage of 30kV was applied between the tip and the current collecting plate in a state in which a temperature in the supply container was controlled at a constant temperature of 70 ℃, and the polymer spinning solution in the supply container was jetted under pressure for 8 hours, to prepare a nanofiber spinning layer having a width of 25cm, a length of 4cm, and a thickness of 100 μm.

< production example 2> production of nanofiber spun layer

An electrolyte membrane was produced by the same procedure as in production example 1, except that the temperature in the supply container of the polymer spinning solution of the electrospinning device was controlled to a constant temperature of 45 ℃.

< production example 3> production of nanofiber spun layer

An electrolyte membrane was produced by the same procedure as in production example 1, except that the temperature in the supply container of the polymer spinning solution of the electrospinning device was controlled to a constant temperature of 35 ℃.

< production example 4> production of nanofiber spun layer

An electrolyte membrane was produced by the same procedure as in production example 1, except that the temperature in the supply container of the polymer spinning solution of the electrospinning device was controlled to a constant temperature of 25 ℃.

< example 1-1> production of electrolyte Membrane

The nanofiber spun layer manufactured in the manufacturing example 1 was immersed in an ion conductor, that is, a PFSA-based polymer was immersed in an ion conductor dispersed in a solvent, which is a solvent in which water and ethanol were mixed at a ratio of 1:1, to prepare an electrolyte membrane.

< example 2-1> production of electrolyte Membrane

An electrolyte membrane was manufactured by the same procedure as in the example 1-1, except that the nanofiber spun layer manufactured in the manufacturing example 2 was used as the nanofiber spun layer.

< example 3-1> production of electrolyte Membrane

An electrolyte membrane was manufactured by the same procedure as in the example 1-1, except that the nanofiber spun layer manufactured in the manufacturing example 3 was used as the nanofiber spun layer.

< example 4-1> production of electrolyte Membrane

An electrolyte membrane was manufactured by the same procedure as in example 1-1, except that the nanofiber spun layer manufactured in the manufacturing example 4 was used as the nanofiber spun layer.

< examples 1-2> production of Unit cell

Carbon papers as gas diffusion layers were laminated on both sides of the electrolyte membrane manufactured in the example 1-1, and then a 210 μm gasket for maintaining gas tightness was adhered to a portion of the polymer electrolyte except for an electrode portion centering on the membrane electrode assembly, and an anode plate having a flow path for adding hydrogen and applying uniform pressure and a cathode plate for adding air and applying uniform pressure to the membrane electrode assembly were adhered to the membrane electrode assembly to manufacture a unit cell.

< example 2-2> production of Unit cell

A unit cell was manufactured by the same procedure as in example 1-2, except that the electrolyte membrane manufactured in example 2-1 was used as an electrolyte membrane.

< example 3-2> production of Unit cell

A unit cell was manufactured by the same procedure as in example 1-2, except that the electrolyte membrane manufactured in example 3-1 was used as an electrolyte membrane.

< example 4-2> production of Unit cell

A unit cell was manufactured by the same procedure as in example 1-2, except that the electrolyte membrane manufactured in example 4-1 was used as an electrolyte membrane.

< test example 1> Observation of microstructure by FE-SEM

The fine structures of the nanofiber spinning layer manufactured in the manufacturing example 1 and the nanofiber spinning layer manufactured in the manufacturing example 4 were photographed using a Field Emission Scanning Electron microscope (FE-SEM) device manufactured by hitachi under the product name SU-70, and are shown in fig. 1 and fig. 2, respectively.

As a result of observing the fine structure of the nanofibers of the present invention, it was confirmed that when the temperature of the polymer dope was controlled to a certain range or not and the diameters of the fibers were different in the production of the nanofiber spun layer, the solvent remained was not sufficiently volatilized and a phenomenon in which some of the nanofibers were dissolved in the solvent was caused when the temperature was not maintained to a certain level in the electrospinning.

< test example 2> measurement of Performance of Unit cell

In order to compare the performance of the fuel cells of the present invention, the performance of the unit cell was measured under the following conditions.

Relative humidity: 80 percent of

Battery temperature: 65 deg.C

Gas supply: anode-hydrogen/cathode-air

A measuring device: CNL company fuel cell performance TEST (TEST STATION)

Surface area of electrolyte membrane: 25cm²

First, the current-voltage values of the respective unit cells of examples 1-2 to 4-2 were measured, and current-voltage curves are shown in fig. 3. Specifically, the current density of each unit cell at 0.6V is shown in table 1 below.

[ Table 1]

Unit cell	)
		Examples 1 to 2	900
Examples 2 to 2	800
		Examples 3 to 2	740
Example 4 to 2	710

As shown in FIG. 3, it can be seen that the power generation performance of the fuel cells of examples 1-2 and 2-2, in which the electrolyte membranes manufactured by maintaining the temperature of the polymer spinning solution in the supply container at 45 ℃ and 70 ℃ and applying a voltage at the time of manufacturing the electrolyte membranes were used, was particularly superior to that of the fuel cells of examples 3-2 and 4-2, in which the electrolyte membranes manufactured by maintaining the temperature of the polymer spinning solution in the supply container at 45 ℃ and 70 ℃ and applying a voltage were usedThe electrolyte membranes manufactured by maintaining the temperature of the polymer spinning solution in the supply container at 35 c and 25c, respectively, and applying a voltage were used in the cells, and it was confirmed that the fuel cells of examples 1-2 had more excellent power generation performance than the fuel cells of examples 2-2. In particular, it was confirmed that the current density of the fuel cell of example 1-2 was 900mA/cm at 0.6V²And has a current of 710mA/cm²The power generation performance of the fuel cell of example 4-2 was 27% superior to that of the fuel cell of example 4-2.