阅读说明：本技术 复合电解质膜、增强复合电解质膜和包括其的燃料电池 (Composite electrolyte membrane, reinforced composite electrolyte membrane, and fuel cell including the same ) 是由 朴规利 金赫 闵敏圭 金志轩 裴仁圣 于 2016-09-01 设计创作，主要内容包括：本说明书涉及一种复合电解质膜、增强复合电解质膜和包括其的燃料电池。(The present specification relates to a composite electrolyte membrane, a reinforced composite electrolyte membrane, and a fuel cell including the same.)

1. A composite electrolyte membrane comprising:

an ion-conductive polymer; and

two or more types of silica particles having different average particle diameters.

2. The composite electrolyte membrane according to claim 1, wherein the two or more types of silica particles include first silica particles and second silica particles, and the first silica particles have an average particle diameter larger than that of the second silica particles.

3. The composite electrolyte membrane according to claim 1, wherein the two or more types of silica particles include first silica particles having an average particle diameter of 70nm to 800nm and second silica particles having an average particle diameter of 3nm to 40 nm.

4. The composite electrolyte membrane according to claim 1, wherein the two or more types of silica particles include first silica particles having an average particle diameter of 100nm to 250nm and second silica particles having an average particle diameter of 5nm to 15 nm.

5. The composite electrolyte membrane according to claim 3, wherein the difference in average particle diameter between the first silica particles and the second silica particles is in the range of 50nm to 400 nm.

6. The composite electrolyte membrane according to claim 2, wherein the content of the second silica particles in the composite electrolyte membrane is 50 to 400 parts by weight based on 100 parts by weight of the first silica particles.

7. The composite electrolyte membrane according to claim 1, wherein the silica particles are contained in an amount of 1 to 20 parts by weight, based on 100 parts by weight of the ion-conductive polymer.

8. The composite electrolyte membrane according to claim 3, wherein the first silica particles have a specific surface area of 800m²More than g.

9. The composite electrolyte membrane according to claim 3, wherein the specific surface area of the second silica particles is 200m²G to 400m²In the range of/g.

10. The composite electrolyte membrane according to claim 3, wherein the first silica particles are porous.

11. The composite electrolyte membrane according to claim 3, wherein the first silica particles have a pore size in the range of 1nm to 5 nm.

12. The composite electrolyte membrane according to claim 1, wherein the two or more types of silica particles are disposed inside the ion-conductive polymer and dispersed in the ion-conductive polymer.

13. The composite electrolyte membrane according to claim 1, having an ionic conductivity of 0.001mS/cm to 500 mS/cm.

14. The composite electrolyte membrane according to claim 1, wherein the ion-conducting polymer is a hydrocarbon-based polymer.

15. The composite electrolyte membrane according to claim 14, wherein the weight average molecular weight of the hydrocarbon-based polymer is 100,000 to 2,000,000.

16. The composite electrolyte membrane according to claim 14, wherein the hydrocarbon-based polymer is selected from the group consisting of sulfonated benzimidazole polymers, sulfonated polyimide-based polymers, sulfonated polyetherimide-based polymers, sulfonated polyphenylene sulfide-based polymers, sulfonated polysulfone-based polymers, sulfonated polyether sulfone-based polymers, sulfonated polyether ketone-based polymers, sulfonated polyether ether ketone-based polymers, and sulfonated polyphenylquinoxaline-based polymers.

17. A reinforced composite electrolyte membrane comprising:

a mixed layer including an ion-conducting region and a porous support; and

a conductive layer comprising an ion conductive polymer disposed on at least one surface of the mixed layer, wherein the conductive layer comprises first silica particles,

the mixed layer contains second silica particles having a smaller average particle diameter than the first silica particles.

18. The reinforced composite electrolyte membrane according to claim 17, wherein the first silica particles have an average particle diameter of 70nm to 800nm, and the second silica particles have an average particle diameter of 3nm to 40 nm.

19. The reinforced composite electrolyte membrane according to claim 17, wherein the ion-conducting region comprises an ion-conducting polymer.

20. The reinforced composite electrolyte membrane according to claim 19, wherein the ion conducting polymer is a hydrocarbon-based polymer.

21. A membrane electrode assembly comprising the composite electrolyte membrane according to any one of claims 1 to 16.

22. A membrane electrode assembly comprising the reinforced composite electrolyte membrane according to any one of claims 17 to 20.

23. A fuel cell comprising the membrane electrode assembly of claim 21.

24. A fuel cell comprising the membrane electrode assembly of claim 22.

Technical Field

This application claims the benefit of korean patent application No.10-2015 0123700, filed by the korean intellectual property office at 2015, 09/01, which is incorporated by reference in its entirety.

The present application relates to a composite electrolyte membrane, a reinforced composite electrolyte membrane, and a fuel cell including the same.

Background

With recent predictions about the depletion of existing energy sources such as oil and coal, interest in alternative energy sources that can replace these energy sources has increased. As one of such alternative energy sources, fuel cells have high efficiency and do not emit such as NO_xAnd SO_xHave received particular attention, as well as the advantage of having sufficient fuel for use.

A fuel cell is a power generation system that converts chemical reaction energy of a fuel and an oxidant into electric energy, and uses hydrogen, methanol, and hydrocarbons such as butane as the fuel, and oxygen as the oxidant in general.

The fuel cell includes a Polymer Electrolyte Membrane Fuel Cell (PEMFC), a Direct Methanol Fuel Cell (DMFC), a Phosphoric Acid Fuel Cell (PAFC), an Alkali Fuel Cell (AFC), a Molten Carbonate Fuel Cell (MCFC), a Solid Oxide Fuel Cell (SOFC), and the like. Among them, the polymer electrolyte membrane type fuel cell is most actively studied due to its high energy density and high output. Such a polymer electrolyte membrane type fuel cell differs from other fuel cells in that a solid polymer electrolyte membrane is used as an electrolyte instead of a liquid.

The polymer electrolyte membrane type fuel cell has the following basic principle: gas diffusion electrode layers are provided on both surfaces of the polymer electrolyte membrane, water is produced from the polymer electrolyte membrane by a chemical reaction by causing the anode to face the fuel electrode and the cathode to face the oxidation electrode, and the reaction energy thus produced is converted into electric energy.

As a polymer electrolyte membrane used in a polymer electrolyte membrane type fuel cell, a fluorine-based polymer electrolyte membrane is widely known for its high performance and durability. In particular, the fluorine-based polymer electrolyte membrane exhibits more excellent effects in terms of membrane performance and durability even under relatively low humidity conditions, as compared to hydrocarbon-based polymers.

Meanwhile, hydrocarbon-based electrolyte membranes have been actively studied on the basis of price competitiveness as compared to fluorine-based electrolyte membranes, and the performance of electrolyte membranes evaluated by unit cell evaluation has been improved to a level similar to that of fluorine-based electrolyte membranes. However, the performance and durability tend to decrease under the influence of humidity conditions or in a high current density region as compared with a fluorine-based electrolyte membrane, and studies for enhancing these properties have been conducted.

Korean patent application laid-open No.2009-0039180

Disclosure of Invention

Technical problem

The present specification aims to provide a composite electrolyte membrane, a reinforced composite electrolyte membrane, and a fuel cell including the same.

Technical scheme

One embodiment of the present description provides a composite electrolyte membrane comprising: an ion-conductive polymer; and two types of silica particles.

One embodiment of the present description provides a reinforced composite electrolyte membrane including: a mixed layer including an ion-conducting region and a porous support; and a conductive layer including an ion conductive polymer, provided on at least one surface of the mixed layer, wherein the conductive layer includes first silica particles, and the mixed layer includes second silica particles having a smaller average particle diameter than the first silica particles.

One embodiment of the present specification provides a membrane electrode assembly including the composite electrolyte membrane or the reinforced composite electrolyte membrane.

One embodiment of the present specification provides a fuel cell including the membrane electrode assembly.

Advantageous effects

According to one embodiment of the present description, excellent performance is obtained under a humidity condition while using a hydrocarbon-based electrolyte membrane having price competitiveness as compared to a conventional fluorine-based electrolyte membrane.

Further, according to one embodiment of the present description, superior performance is obtained in a high current density region as compared to a conventional hydrocarbon-based electrolyte membrane.

In other words, the use of a membrane electrode assembly including a composite electrolyte membrane according to one embodiment of the present specification in a fuel cell has a positive effect on improving fuel cell performance and/or Open Circuit Voltage (OCV).

Drawings

Fig. 1 is a diagram simulatively showing a composite electrolyte membrane including two types of silica according to an embodiment of the present specification;

fig. 2 is a view showing a simulated reinforced composite electrolyte membrane including second silica particles in a mixed layer and first silica particles in a conductive layer as a reinforced composite electrolyte membrane according to an embodiment of the present specification;

fig. 3 is a view showing a simulated reinforced composite electrolyte membrane including second silica particles in a mixed layer and first silica particles and second silica particles in a conductive layer as a reinforced composite electrolyte membrane according to an embodiment of the present specification;

fig. 4 is a graph in which current densities of a hydrocarbon-based composite electrolyte membrane containing two types of silica, which was prepared by an example of the present specification, and a hydrocarbon-based composite electrolyte membrane containing only one type of silica, which was prepared by a comparative example, were measured;

fig. 5 is a graph in which open circuit voltage values were measured for the case where two types of silicon dioxide were contained prepared by an example of the present specification and the case where only one type of silicon dioxide was contained by a comparative example;

fig. 6 is a diagram showing the structure of a fuel cell according to an embodiment of the present specification.

Detailed Description

Hereinafter, the present specification will be described in detail.

In this specification, the description that a specific component is "on" another component includes not only the case where one component is adjacent to another component but also the case where another component is present between the two components.

In this specification, unless specifically stated otherwise, a description that a specific part "includes" a specific component means that other components can also be included, and is not exclusive of other components.

One embodiment of the present description provides a composite electrolyte membrane comprising: an ion-conductive polymer; and two or more types of silica particles having different average particle diameters.

The present disclosure is directed to developing a hydrocarbon-based electrolyte membrane having better performance under various conditions such as a humid or high current density region by improving the performance of the existing hydrocarbon-based electrolyte membrane.

In other words, according to one embodiment of the present specification, the water absorption rate of the electrolyte membrane is increased by adding two types of silica particles (hydrophilic inorganic materials) to the hydrocarbon-based polymer, and the overall performance of the fuel cell can be improved by increasing the resulting proton conductivity.

The present disclosure uses two or more types of microparticles having different average particle diameters. By using such two or more types of fine particles having different average particle diameters, the film performance and/or durability under low humidity conditions or in a current density region can be effectively improved.

In the present specification, the average particle diameter is measured by TEM observation, and the average diameter of the particles is measured.

According to one embodiment of the present specification, the two or more types of silica particles may include first silica particles and second silica particles, and an average particle diameter of the first silica particles may be larger than an average particle diameter of the second silica particles.

In other words, according to one embodiment of the present specification, when large-sized first silica particles and small-sized second silica particles are used in a composite electrolyte membrane, a performance enhancing effect can be achieved by hydrophilicity of the large-sized porous first silica particles, and by the disadvantage of the uneven dispersion of the large-sized first silica particles being compensated for by the small-sized second silica particles, an overall enhancement of membrane performance can be achieved, and by the presence of the second silica particles that effectively prevent a decrease in durability, it is effective in preventing the OCV from decreasing.

According to one embodiment of the present specification, the two types of silica particles include first silica particles having an average particle diameter of 70nm to 800nm and second silica particles having an average particle diameter of 3nm to 40 nm. Further, according to an embodiment of the present specification, the average particle diameter of the first silica particles is more preferably 100nm to 250nm, and the average particle diameter of the second silica particles is more preferably 5nm to 15 nm.

According to one embodiment of the present specification, the average particle diameters of the first silica particles and the second silica particles satisfying the above ranges are effective in obtaining excellent properties under low humidity conditions.

In addition, according to an embodiment of the present specification, the difference in average particle diameter between the first silica particles and the second silica particles may be in the range of 30nm to 700nm, more preferably in the range of 100nm to 200 nm.

According to one embodiment of the present description, the first silica particles may be synthetic silica and porous, and the second silica particles may be fumed silica.

According to an embodiment of the present specification, in the composite electrolyte membrane, the second silica particles may be included in an amount of 50 to 400 parts by weight, more preferably 60 to 200 parts by weight, based on 100 parts by weight of the first silica particles.

According to an embodiment of the present specification, in the composite electrolyte membrane, the silica particles may be included by 1 to 20 parts by weight, preferably 1 to 10 parts by weight, and more preferably 1 to 5 parts by weight, based on 100 parts by weight of the hydrocarbon-based polymer. The content of the silica particles refers to the total content of two or more types of silica particles, for example, when formed of two types of silica particles, i.e., a first silica particle and a second silica particle, the content of the silica particles refers to a value at which the content of the first silica particle and the content of the second silica particle are added.

According to one embodiment of the present specification, the specific surface area of the first silica particles is preferably 800m²More than g. The specific surface area is 800m²The first silica particles of/g or more are effective in improving the performance under low humidity conditions, and more preferably, the specific surface area of the first silica particles may be greater than or equal to 800m²A ratio of 1,000m or less to/g²/g。

According to one embodiment of the present specification, the first silica particles and the second silica particles may have a spherical shape, a polygonal shape, a rod shape, a cylindrical shape, or the like, and their shapes are not particularly limited, but are preferably spherical.

According to one embodiment of the present specification, the first silica particles preferably have porosity, and the first silica particles having porosity are effective in increasing hydrophilicity.

Specifically, according to one embodiment of the present specification, the pore size of the first silica particles may be in the range of 1nm to 5 nm.

According to one embodiment of the present specification, the two or more types of silica particles preferably have a wide specific surface area and a uniform particle size.

In addition, in the composite electrolyte membrane according to one embodiment of the present description, the two or more types of silica particles may be provided inside the hydrocarbon-based polymer or may be dispersed in the hydrocarbon-based polymer.

According to one embodiment of the present specification, it is effective to include two or more types of silica particles in the composite electrolyte membrane because the silica particles are relatively uniformly distributed in the interior of the hydrocarbon-based polymer.

One embodiment of the present description provides a reinforced composite electrolyte membrane including: a mixed layer including an ion-conducting region and a porous support; and a conductive layer including an ion conductive polymer, provided on at least one surface of the mixed layer, wherein the conductive layer includes first silica particles, and the mixed layer includes second silica particles having a smaller average particle diameter than the first silica particles.

In the present specification, with respect to the description of the first silica particles and the second silica particles, the description provided above can be applied in the same manner.

According to one embodiment of the present description, in the reinforced composite electrolyte membrane, the conductive layer may include both the first silica particles and the second silica particles.

In other words, in the reinforced composite electrolyte membrane according to one embodiment of the present specification, the conductive layer may include only the first silica particles, and the mixed layer may include only the second silica particles.

Further, according to an embodiment of the present specification, the conductive layer may include first silica particles and second silica particles, and the mixed layer may include only the second silica particles. The description provided above can be applied in the same manner for the description of the first silica particles and the second silica particles, and specifically, the average particle diameter of the first silica particles is larger than that of the second silica particles.

According to one embodiment of the present specification, in order to provide mechanical properties and dimensional stability of the membrane, a porous support may be used in the reinforced composite electrolyte membrane, and as the porous support, since it is necessary to maintain mechanical durability without degrading performance, it is necessary to select a support formed of an appropriate material having excellent mechanical properties while having high porosity.

In the present specification, the ion conductive region may refer to a region excluding a skeleton formed of a porous support. Further, when only the support is present, the ion conductive region may be a pore region. Further, by including an ion conductive material, ions can migrate through the ion conductive material.

According to one embodiment of the present description, the porous carrier may include a hydrocarbon-based substance, and the carrier may be a hydrocarbon-based carrier.

According to one embodiment of the present description, the porous support may include a semi-crystalline polymer. According to one embodiment of the present description, the semi-crystalline polymer may have a crystallinity ranging from 20% to 80%.

In addition, according to one embodiment of the present description, the semi-crystalline polymer may include, but is not limited to, polyolefins, polyamides, polyesters, polyacetals (or polyoxymethylenes), polysulfides, polyvinyl alcohols, copolymers thereof, and combinations thereof.

According to one embodiment of the present description, the porous carrier may include a material derived from a polyolefin-based material.

According to one embodiment of the present description, the polyolefin may include polyethylene (LDFE, LLDPE, HDPE, UHMWPE), polypropylene, polybutene, polymethylpentene, copolymers thereof and blends thereof.

Polyamides may include, but are not limited to, polyamide 6, polyamide 6/6, nylon 10/10, polyphthalamide (PPA), copolymers thereof, and blends thereof.

The polyester may include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), poly-1, 4-cyclohexylenedimethylene terephthalate (PCT), polyethylene naphthalate (PEN), and Liquid Crystal Polymer (LCP), but is not limited thereto.

Polysulfides include, but are not limited to, polyphenylene sulfide, polyethylene sulfide (polyvinylsulfide), copolymers thereof, and blends thereof.

Polyvinyl alcohols include, but are not limited to, ethylene-vinyl alcohol, copolymers thereof, and blends thereof.

According to one embodiment of the present description, the ion-conducting region may comprise greater than or equal to 60% by volume and less than or equal to 100% by volume, preferably greater than or equal to 70% by volume and less than or equal to 100% by volume of the ion-conducting polymer.

According to one embodiment of the present specification, when the ion-conductive polymer is included in the ion-conductive region within the above range, the reinforced composite electrolyte membrane may exhibit excellent ion conductivity.

According to an embodiment of the present description, the thickness of the mixed layer may be in the range of 2 μm to 10 μm, preferably in the range of 2 μm to 5 μm.

Further, according to an embodiment of the present specification, the thickness of the conductive layer may be in a range of 1 μm to 10 μm, preferably in a range of 1 μm to 5 μm.

According to one embodiment of the present description, the reinforced composite electrolyte membrane may have conductive layers provided on both surfaces of the mixed layer, and the mixed layer and the two conductive layers may respectively contain silica particles having different average particle diameters.

According to one embodiment of the present description, the ion-conducting region may comprise an ion-conducting polymer, which may include a cation-conducting polymer and/or an anion-conducting polymer. Further, the ion conducting polymer may include a proton conducting polymer.

According to one embodiment of the present specification, the ion-conductive polymer may use a material generally used as an electrolyte membrane of a fuel cell, and, although it is not particularly limited, is preferably a hydrocarbon-based polymer.

According to one embodiment of the present specification, the hydrocarbon-based polymers are different from each other, and may each include one, two or more types selected from sulfonated benzimidazole-based polymers, sulfonated polyimide-based polymers, sulfonated polyetherimide-based polymers, sulfonated polyphenylene sulfide-based polymers, sulfonated polysulfone-based polymers, sulfonated polyether sulfone-based polymers, sulfonated polyether ketone-based polymers, sulfonated polyphenylene quinoxaline-based polymers, and sulfonated partially fluorine-introduced polymers (sulfonated partially fluorinated polymers).

According to one embodiment of the present specification, the polymer to which a sulfonated partial fluorine system is introduced may be a polymer in which a sulfo group is bonded to at least one side chain, and the ratio of the number of carbon atoms to the number of fluorine atoms contained in the polymer is more than 1:0 and less than 1: 1.

According to one embodiment of the present description, the electrolyte membrane may have an ionic conductivity of 0.001mS/cm to 500mS/cm, which refers to an ionic conductivity from RH 32% to RH 100%.

According to one embodiment of the present specification, the weight average molecular weight of the hydrocarbon-based polymer is 100,000 to 2,000,000.

One embodiment of the present specification provides a membrane electrode assembly including the composite electrolyte membrane or the reinforced composite electrolyte membrane.

In addition, one embodiment of the present specification provides a fuel cell including the membrane electrode assembly.

According to one embodiment of the present specification, when two or more types of silica particles are contained in the composite electrolyte membrane or the reinforced composite electrolyte membrane and used in a fuel cell, a membrane performance enhancing effect is obtained. In other words, when only the first silica particles are used, the film property-enhancing effect is more excellent than when only the second silica particles are used, however, there is a problem in that the Open Circuit Voltage (OCV) is greatly reduced. In view of the above, the inventors of the present disclosure have completed the present disclosure by being able to enhance the membrane performance and/or prevent the problem of a decrease in Open Circuit Voltage (OCV) by including two or more types of silica particles including first silica particles and second silica particles in a composite electrolyte membrane or a reinforced composite electrolyte membrane.

The fuel cell according to an embodiment of the present specification includes a fuel cell well known in the art. For example, the fuel cell may be any one of a polymer electrolyte membrane type fuel cell (PEMFC), a direct methanol type fuel cell (DMFC), a phosphoric acid type fuel cell (PAFC), an alkali type fuel cell (AFC), a molten carbonate type fuel cell (MCFC), and a solid oxide type fuel cell (SOFC).

Specifically, according to one embodiment of the present specification, the fuel cell may include: a stack including membrane electrode assemblies and separators disposed between the membrane electrode assemblies; a fuel supply unit that supplies fuel to the stack; and an oxidizer supply unit supplying an oxidizer to the stack.

Fig. 6 is a view simulatively showing the structure of a fuel cell according to an embodiment of the present specification, and the fuel cell is formed to include a stack (60), an oxidant supply unit (70), and a fuel supply unit (80).

The stack (60) includes one, two or more membrane electrode assemblies, and when two or more membrane electrode assemblies are included, a separator is disposed therebetween.

The separator serves to prevent the membrane electrode assemblies from being electrically connected to each other and to deliver fuel and oxidant supplied from the outside to the membrane electrode assemblies.

The oxidizer supply unit (70) is used to supply an oxidizer to the stack (60). Oxygen is typically used as the oxidant, and a pump (70) may be used to inject the oxygen or air.

The fuel supply unit (80) is used to supply fuel to the stack (60), and may be formed of a fuel tank (81) that stores fuel and a pump (82) that supplies the fuel stored in the fuel tank to the stack (60). As the fuel, hydrogen gas or gaseous or liquid hydrocarbon fuel may be used, and examples of the hydrocarbon fuel may include methanol, ethanol, propanol, butanol, or natural gas.

Hereinafter, the present specification will be described in detail with reference to examples. However, various forms of modifications may be made to the embodiments according to the present specification, and the scope of the present specification should not be construed as being limited to the embodiments described below. The embodiments of the present description are provided to more fully describe the present description to those of ordinary skill in the art.

< example 1>

1) Production of hydrocarbon-based polymer

To a 1L round bottom flask equipped with a Dean-Stark trap and condenser were added potassium hydroquinone sulfonate (0.9 eq.), 4' -difluorobenzophenone (0.97 eq.), and 3, 5-bis (4-fluorobenzoyl) phenyl (4-fluorophenyl) methanone (0.02 eq.) and potassium carbonate (K) was used under a nitrogen atmosphere₂CO₃) Prepared as a catalyst in dimethyl sulfoxide (DMSO) and benzene solvent. Next, the reaction mixture was stirred in an oil bath at a temperature of 140 ℃ for 4 hours, the azeotropic mixture was removed by adsorbing the azeotropic mixture to a molecular sieve of a Dean-Stark separator while benzene was refluxed, the reaction temperature was raised to 180 ℃, and the resultant was subjected to a polycondensation reaction for 20 hours. After the reaction was complete, the temperature of the reactants was lowered to 60 ℃,4' -difluorobenzophenone (0.2275 equivalents), 9-bis (hydroxyphenyl) fluoride (0.335 equivalents) and 3, 5-bis (4-fluorobenzoyl) phenyl (4-fluorophenyl) -methanone (0.005 equivalents) were added to the same flask and K was used₂CO₃As a catalyst, the reaction was started again under a nitrogen atmosphere using dimethyl sulfoxide (DMSO) and benzene. Next, the reaction mixture was stirred in an oil bath at a temperature of 140 ℃ for 4 hours again, the azeotropic mixture was removed by adsorbing the azeotropic mixture to a molecular sieve of a Dean-Stark separator while benzene was refluxed, the reaction temperature was raised to 180 ℃, and the resultant was subjected to a polycondensation reaction for 20 hours. Then, the temperature of the reaction was lowered to room temperature, dimethyl sulfoxide (DMSO) was further added to dilute the product, and the diluted product was poured into an excess amount of methanol to separate the copolymer from the solvent. Thereafter, excess potassium carbonate was removed using water, and the copolymer obtained by filtration was dried in a vacuum oven at 80 ℃ for 12 hoursThe above, a branched sulfonated multiblock copolymer in which hydrophobic blocks and hydrophilic blocks are alternately connected by chemical bonds is prepared.

2) Preparation of silica particles (1)

Silica is synthesized by a seed mediation method (seed method) of the modified stober method, and during the synthesis, a silica precursor having a carbon chain is added so as to generate pores by a heat treatment process after the synthesis. The silica prepared has a relatively uniform size and a specific surface area of 800m²More than g.

3) Preparation of silica particles (2) (fumed silica)

Fumed silica is produced by a high temperature gas phase reaction and is produced by the formation of chlorosilanes hydrolyzed in a flame above 1000 ℃ with oxygen and hydrogen. The base particles formed in the flame are connected to each other by collision to form secondary particles while the surface is still molten, and they are connected in the form of three-dimensional branches to produce aggregates or agglomerates. After the reaction, the hydrogen chloride gas remaining in the silica was removed under high-temperature air conditions. The density of fumed silica immediately after preparation is very low, and therefore, the density is increased to 50g/L or more by a gas bleeding method using a pressure reducing device.

4) Preparation of silica-added composite film

The composite membrane composition was prepared by adding the silica particles (1) and the silica particles (2) to a Dimethylsulfoxide (DMSO) solvent so that the content ratio of the silica particles (total weight of the silica particles (1) and the silica particles (2)) to the hydrocarbon-based polymer was 5% by weight, and filtering the resultant. The composite film composition was cast onto a substrate as a polymer film using a doctor blade on a horizontal plate of a coater of a clean bench, the resultant was kept at 50 ℃ for 2 hours or more to be soft-dried, and then the resultant was placed in an oven set at 100 ℃ and dried for one day to prepare a silica-added hydrocarbon-based composite film.

< comparative example 1>

A hydrocarbon-based electrolyte membrane was prepared in the same manner as in example 1, except that no silica particles were added.

< comparative example 2>

A silica-added hydrocarbon-based composite membrane was prepared in the same manner as in example 1, except that the silica particles (1) were added in a content ratio of 5 wt% with respect to the hydrocarbon-based polymer.

< comparative example 3>

A silica-added hydrocarbon-based composite membrane was prepared in the same manner as in example 1, except that the silica particles (2) were added in a content ratio of 5 wt% with respect to the hydrocarbon-based polymer.

< evaluation example 1> measurement of Current Density

Scanning 0mA/cm in constant current mode by using PEMFC TEST Station²To 1500mA/cm²The current density of the hydrocarbon-based composite membranes prepared in example 1 and comparative examples 2 and 3 was measured, and the measurement was performed based on 70 ℃ under an operating condition of 50% relative humidity. The measurement results are shown in fig. 4.

In fig. 4, it can be confirmed that example 1 using two types of silica (1) and silica (2)) has a higher current density than comparative examples 2 and 3 using only one type of silica, and thus it can be seen that the performance is more excellent when used in a fuel cell.

< evaluation example 2> measurement of Open Circuit Voltage (OCV)

Measurement at 0mA/cm using PEMFC TEST Station in open circuit voltage mode²Potential value at the end of the time interval, and open circuit voltage was measured at 70 ℃ under operating conditions of 50% relative humidity.

The results of experimental measurement of the open circuit voltage values are shown in fig. 5, and it can be determined from fig. 5 that example 1 using two types of silica particles has a higher open circuit voltage than comparative example 2 using the first silica particles, and has the same open circuit voltage value as comparative example 3 using only the second silica particles.

In other words, when only the first silica particles are used, the film property-enhancing effect is more excellent than when only the second silica particles are used, however, there is a problem in that the Open Circuit Voltage (OCV) is greatly reduced. However, it was confirmed that the fuel cell using two types of silica particles according to the embodiment of the present disclosure can prevent the open circuit voltage lowering problem while exhibiting excellent membrane performance.