KR20070003469A - Method for surface treatment of electrolyte membrane, surface-treated electrolyte membrane and polymer electrolyte membrane fuel cell including the electrolyte membrane - Google Patents

Abstract

Provided are a method for treating the surface of an electrolyte membrane to control the roughness of an electrolyte membrane precisely without the change of other physical properties an electrolyte membrane whose surface treated by the method, and a polymer an electrolyte membrane fuel cell containing the surface-treated electrolyte membrane. The method comprises the step of irradiating an ion beam on the surface of an electrolyte membrane to treat the surface of an electrolyte membrane. Preferably the ion beam has an amount per unit area of 1Î10^15 to 5Î10^16 ions/cm^2 at an ion beam energy of 1keV. Preferably the ion beam is an Ar^+ beam; and an electrolyte membrane is a Nafion membrane.

Description

Method for surface treatment of electrolyte membrane, surface-treated electrolyte membrane and polymer electrolyte membrane fuel cell including the electrolyte membrane}

1A is an SEM photograph showing the surface shape of the film of the comparative example of the present invention.

1B is a SEM photograph showing the surface shape of the film of Example 1 of the present invention.

1C is a SEM photograph showing the surface shape of the film of Example 2 of the present invention.

1D is a SEM photograph showing the surface shape of the film of Example 3 of the present invention.

1E is an SEM photograph showing the surface shape of the film of Example 4 of the present invention.

2 is a graph showing the FTIR-ART spectrum of a film of Comparative Examples and Examples of the present invention.

3A is an i-V characteristic curve showing the performance of a unit cell using the film of Comparative Examples and Examples of the present invention.

3B is a Nyquist plot showing the polarization resistance of unit cells using the membranes of Comparative Examples and Examples of the present invention.

3C is a CV graph of a unit cell using the membrane of the comparative examples and examples of the present invention.

4 is a graph showing a cell voltage at 800 mA / cm ² , a charge transfer resistance at 0.8 V, and a catalyst utilization rate according to a change in the amount of ions in the unit cell using the membranes of the comparative examples and examples of the present invention.

5A is a polarization curve according to the change of the catalyst loading amount of a unit cell using the membrane of the comparative example of the present invention.

5B is a polarization curve according to the change of the catalyst loading amount of a unit cell using the membrane of Example 3 of the present invention.

5C is a graph showing the cell voltage at 800 mA / cm ² according to the change of the catalyst loading in each of Example 3 and Comparative Example of the present invention.

6 is a graph showing the charge transfer resistance according to the change of the catalyst loading amount of the unit cell using the membrane of Example 3 and Comparative Example of the present invention.

Sally-Ann Sheppard, Sheelagh A. Campbell, James R. Smith, Grongar W. Lloyd, Thomas R. Ralph, Frank C. Walsh, Analyst, 123 (1998) 1923-1929.

2. Lawrance; Richard J., Wood; Linda D., US Pat. No. 4,272,353.

3. Kawagoe, Y .; Namie, S .; Nomura, M .; Kumakura, T .; Shiozaki, K .; Nakajima, D. Y. in: U. Stimming, S. C. Singhal, H. Tagawa, and W. Lehnert, (Eds.), Proceedings from the Solid Oxide Fuel Cells V, PV97-40, The Electrochemical Society, 1997, pp. 549-556.

The present invention relates to a surface treatment method of an electrolyte membrane, a surface treated electrolyte membrane and a polymer electrolyte membrane fuel cell including the same. Specifically, a surface treatment method of an electrolyte membrane for improving cell performance by performing a surface treatment through ion collision, The present invention relates to a surface-treated electrolyte membrane and a polymer electrolyte membrane fuel cell including the same.

Polymer Electrolyte Membrane Fuel Cell (PEMFC) is a clean and efficient energy conversion device that can be used as a mobile or stationary power source.

At the interface between the electrolyte membrane and the electrode catalyst among the components of the PEMFC, an electrochemical reaction occurs by contact with a reaction gas. Thus, the interface between the electrolyte and the electrode catalyst plays an important role in improving cell performance.

In order to improve the electrochemical reaction, the contact between the electrolyte and the catalyst particles should be increased. For this, a method of treating the surface of the membrane and a method of increasing the amount of electrolyte in the catalyst layer may be considered.

However, the method of increasing the amount of electrolyte in the catalyst layer is limited and a method of treating the surface of the membrane should be considered.

Methods are known in the art for treating the surface of a film. For example, a method of improving the cell performance by increasing the number of catalysts in contact with an electrolyte on a Nafion membrane by coating a platinum (Pt) catalyst on the surface of an electrolyte membrane roughened by SiC paper is known (prior art document). 1). And it is known that the electrolyte roughened by SiC paper shows high performance when it is applied to the electrolysis of water (refer prior art document 2).

Moreover, it is known that the contact area between an YSZ electrolyte membrane and an electrode increases by roughening the surface of a membrane (refer prior art document 3).

However, in the conventional surface treatment methods, it is difficult to precisely control the surface shape of the electrolyte due to the use of physical friction and the like, and thus, the reproducibility is poor and the performance improvement of the cell to which the electrolyte membrane is applied is not consistent.

Accordingly, the present invention has been made to solve the above problems, the object of the present invention is to precisely control the surface roughness of the electrolyte membrane without changing the performance of the electrolyte membrane, such as ionic conductivity, non-hydrophilic characteristics and chemical properties of the surface Accordingly, to provide an electrolyte membrane surface-treated according to the electrolyte membrane surface treatment method to achieve an improved performance of the fuel cell in which the electrolyte membrane is used, and a fuel cell having the same.

The object of the present invention as described above is achieved by the surface treatment method of the electrolyte membrane, in which the surface of the electrolyte membrane is treated by irradiating an ion beam to the surface of the electrolyte membrane.

The object of the present invention as described above is achieved by a surface-treated electrolyte membrane, wherein the surface of the electrolyte membrane is irradiated with an ion beam.

The object of the present invention as described above is achieved by a polymer electrolyte membrane fuel cell, comprising the electrolyte membrane in a polymer electrolyte membrane fuel cell.

Hereinafter, the surface treatment method of the electrolyte membrane, the surface-treated electrolyte membrane and the polymer electrolyte membrane fuel cell including the same according to the present invention will be described in detail.

In the present invention, the surface roughness is controlled to increase the effective surface area of the surface of the electrolyte membrane in which the three-phase interface is formed, but unlike the conventional method, the surface roughness is more precise and highly reproducible without changing the ionic conductivity, non-hydrophilicity, and chemical properties of other surfaces. Perform surface treatment. To this end, in the present invention, the ion beam irradiation impinges ions on the surface of the electrolyte membrane, and in particular, in order to improve cell performance, the amount of ions irradiated per unit area under constant ion beam energy during ion beam irradiation [i.e. Ion dose density; Hereafter referred to as "ion amount density".

Specifically, in the present invention, the cell performance was measured by irradiating an ion beam while varying the ion amount density of Ar ⁺ ions on the surface of the Nafion electrolyte membrane and changing the catalyst loading amount. As a result, it was found that the cell performance was the best when the ion amount density was 5 × 10 ¹⁶ ions / cm ² when the ion beam energy was constant at 1 keV during the ion beam irradiation. On the other hand, as a result of the experiment according to the change in the catalyst loading amount, it can be seen that using the surface treatment method of the present invention can reduce the amount of catalyst loaded.

Hereinafter, the present invention will be described in more detail by explaining preferred embodiments of the present invention. However, the present invention is not limited to the following examples, and various forms of embodiments can be implemented within the scope of the appended claims, and the following examples are only common in the art while making the disclosure of the present invention complete. It is intended to facilitate the implementation of the invention to those with knowledge.

Examples  And Comparative example  Membrane manufacturing

Pre-cleaned and dried Nafion 112 membrane (Due Pont, Inc.) was used to prepare specimens (comparative) that were not surface treated with an ion beam and specimens that were surface treated with an ion beam (example).

An argon ion (Ar ⁺ ) beam was used as the ion beam. Argon ion beams were generated from cold hollow cathode type ion sources and the ion beam energy was adjusted to 1.0 keV. The ion amount density was varied from 1 × 10 ¹⁵ to 10 ¹⁷ ions / cm ² by adjusting the exposure time and the current density of the ion beam.

The specimen of Example 1 had an ion quantity density of 1 × 10 ¹⁵ ions / cm ² , the specimen of Example 2 had an ion quantity density of 1 × 10 ¹⁶ ions / cm ² , and the specimen of Example 3 The ion amount density is 5 × 10 ¹⁶ ions / cm ² , and the specimen of Example 4 is ion amount density 1 × 10 ¹⁷ ions / cm ² .

All specimens of the Comparative Examples and Examples were washed by a general ultrasonic cleaning method. Vacuum pressure was maintained at 0.133 ~ 5.3 × 10 ^-1 kPa.

MEA and unit cell manufacturing

40 wt% Pt / C (Johnson Matthey, Inc.) was mixed with isopropyl alcohol (Baker analyzed HPLC reagent) to prepare a catalyst ink, which was then sonicated for 1 hour. 5 wt% Nafion solution (Due Pont, Inc.) was added to the catalyst ink and sonicated for another hour.

The MEA according to each of the Comparative Examples and Examples was prepared and dried by a CCM (Catalyst Coated Membrane) method in which the catalyst ink was sprayed onto the films of the Comparative Examples and Examples. Active electrode surface area in the manufactured MEA is 25cm ² was was 0.3 mg-Pt / cm ² and 0.2mg-Pt / cm ² with respect to the amount of anode catalyst loading and cas de.

The unit cell was manufactured by combining the prepared MEA with a gas diffusion medium (Sigrcet, SGL Carbon Inc.), a gasket, and a graphite block. Hydrogen and oxygen or air were injected into the anode and cathode after passing through a bubble humidifier at 80 ° C. and 65 ° C. (cell temperature 80 ° C.).

Membrane Characterization- Contact angle Ionic conductivity, FTIR - ATR  Spectral and Surface Shape Evaluation

Moisture contact angle of the membrane was measured by the sessile drop method at room temperature using a contact angle micrometer (Cam Micro, Tantec). Contact angles were measured at ten different positions in the membranes of the Examples and Comparative Examples.

Ion conductivities of the Comparative Examples and Examples were measured by 4-point probe method using IM6 (ZAHNER) at room temperature. The membrane was treated with distilled water for at least 3 days in a closed vessel prior to measurement.

FTIR (Nicolet Magna IR 560 model) was performed on the films of Comparative Examples and Examples in ATR mode. In addition, SEM (Hitachi S-4200) and AFM (Park Scientific Instruments) were used to measure the surface morphology and physical properties of the film.

Evaluation of electrochemical properties of unit cells fabricated with the membranes of Examples and Comparative Examples-cell performance, Polarization  Resistance and catalyst Utilization rate  evaluation

The unit cell performance was evaluated by measuring i-V characteristics using an electronic loader (Daegil Electronics Inc, EL 1000P).

The polarization resistance (R _p ) was evaluated by measuring the AC impedance of the unit cell using a hydrogen electrode as a reference electrode and a counter electrode and an oxygen electrode as a working electrode. IM6 (ZAHNER) was used for impedance measurement and the application frequency was varied from 10 mHz to 10 kHz with an excitation voltage of 5 mV (peak to peak).

Platinum catalyst utilization (Pt utilization) of the electrode was evaluated by Cyclic Voltammograms (CV) measured at a scan rate of 50 mV / s and a cell temperature of 80 ℃. Humidified nitrogen was injected into the working electrode and humidified hydrogen was injected into the counter electrode during the CV measurement.

In the case of hydrogen oxidation or generation reaction, since the overvoltage at the counter electrode is insignificant, the counter electrode was used as the reference electrode in the measurement of the AC impedance and CV.

SEM  Measurement result

Figure 1 is a SEM photograph showing the surface shape of the film of the Examples and Comparative Examples of the present invention, Figure 1a is a SEM photograph showing the surface shape of the film of the Comparative Example of the present invention, Figure 1b is a film of Example 1 of the present invention 1C is a SEM photograph showing the surface shape of the film of Example 2 of the present invention, FIG. 1D is a SEM photograph showing the surface shape of the film of Example 3 of the present invention, and FIG. It is a SEM photograph showing the surface shape of the film of Example 4 of the invention.

As can be seen from FIG. 1A, it was found that the surface of the film of the comparative example was less cracked and smooth.

On the other hand, as can be seen from Figures 1b and 1c, the nodule structure was shown for the membranes of Examples 1 and 2 subjected to surface treatment by ion beams, and this nodule structure was further strengthened in the case of the membrane of Example 2 .

As can be seen from FIGS. 1D and 1E, in the case of the membrane of Example 3, in which the ion amount density was increased more than that of Example 2, the surface of the Nafion membrane was dispersed to show a whisker structure. The whisker length increased further.

AFM  Measurement result

Table 1 summarizes the physical properties of the films of the Examples and Comparative Examples of the present invention.

Ion amount (ion / cm ² ) Height from peak to valley ^* (nm) Average height ^* (nm) RMS roughness ^* (nm) Ionic Conductivity (S / cm) Contact angle (°) Membrane of comparative example 247 74 21 0.119 108 Membrane of Example 1 409 146 31 0.113 111 Membrane of Example 2 836 473 87 0.111 121 Membrane of Example 3 - - - 0.119 111 Membrane of Example 4 1790 1130 204 0.127 123

* Measured with AFM

As can be seen from Table 1, as a result of the AFM analysis, the height from peak to valley also increased greatly from 409 nm to 1790 nm from Example 1 to Example 4 (ie, as the ion amount density was increased) in the films of Examples. . This tendency means that the surface roughness increases with the increase of the ion amount density. And, compared with the film of the comparative example, the RMS roughness of the films of the embodiments increased by 10 nm or more, the RMS roughness was further increased as the ion amount density increased in the films of the examples.

On the other hand, as a result of performing ion conductivity and contact angle analysis separately from the AFM analysis, it was confirmed that there is no significant difference in the film of the comparative examples and examples.

FTIR - ATR  Measurement result

FTIR-ATR measurements were performed on the membranes of the comparative examples and examples to investigate the chemical structures of the comparative examples and examples which showed little difference in contact angle and ion conductivity.

2 is a graph showing the FTIR-ART spectrum of a film of Comparative Examples and Examples of the present invention. In FIG. 2, the membrane of the comparative example is labeled “Untreated”, the membrane of Example 1 is labeled “1 × 10 ¹⁵ Ar ⁺ / cm ² ”, and the membrane of Example 2 is “1 × 10 ¹⁶ Ar ⁺ / cm ² And the membrane of Example 3 is denoted by "5 x 10 ¹⁶ Ar ⁺ / cm ² ", and the membrane of Example 4 is denoted by "1 x 10 ¹⁷ Ar ⁺ / cm ² ".

As can be seen from 2, SO ₃ in a symmetric stretching vibration spectrum, 1056.8 cm ^-1 of the side chain COC at 975.81 cm ^{-1 -} the asymmetric stretching mask by the strong CF ₂ stretching vibration around the symmetric stretching frequency spectrum and 1300 cm ^-1 Vibration spectra were observed. In addition, the strong bands appearing in the 1145.51 cm ⁻¹ and 1201.44 cm ⁻¹ regions correspond to the CF ₂ symmetric and asymmetric stretching vibrations of the polymer. In addition, the OH bending and stretching vibration bands in the regions 1600 to 2000 cm ⁻¹ and 3000 to 3700 cm ⁻¹ correspond to moisture in the film.

The strong band peak positions in Comparative Examples and Examples were found to be identical, meaning that the chemical structure of the polymer did not change during or after the Ar ⁺ collision.

Cell performance improvement result by change of ion amount

As described above, the surface shape of the film was modified by the Ar ⁺ ion flow in the range of 10 ¹⁵ to 10 ¹⁷ ions / cm ² having a constant beam energy of 1 keV. The cell performance of the membranes of these examples was compared with that of the comparative membranes without ion beam irradiation.

Figure 3a is an iV characteristic curve showing the cell performance of the film of the comparative examples and examples of the present invention, Figure 3b is a Nyquist plot showing the polarization resistance of the film of the comparative examples and embodiments of the present invention, 3C is a CV graph of a film of Comparative Examples and Examples of the present invention. In the experiments with respect to FIGS. 3A to 3C, the cathode catalyst loading amount was 0.2 mg-Pt / cm ² , and H ₂ / air was added thereto. 3A to 3C, the membrane of the comparative example is labeled "Untreated", the membrane of Example 1 is labeled "1 x 10 ¹⁵ Ar ⁺ / cm ² ", and the membrane of Example 2 is "1 x 10 ¹⁶ Ar ⁺ / cm ² ″, the membrane of Example 3 is labeled “5 × 10 ¹⁶ Ar ⁺ / cm ² ”, and the membrane of Example 4 is labeled “1 × 10 ¹⁷ Ar ⁺ / cm ² ”.

As can be seen from FIG. 3A, the cell with the surface treated film of the present embodiments showed higher performance in the activation and resistance control regions than the cell with the film of the comparative example. In the case of low ion amount density (Example 1), the performance decrease by the material transfer resistance was shown.

As can be seen from FIG. 3b, in the case of low ion amount density (Example 1), it showed somewhat higher R _P compared to the comparative example, which shows that the surface shape change is not large at low ion amount density. In contrast, the membranes of Examples 2-4 treated with ion flows in excess of 10 ¹⁵ Ar ⁺ / cm ² showed low R _P.

The CV of FIG. 3C shows that the peak current density for hydrogen absorption in the case of the membrane of the examples is higher than that of the membrane of the comparative example. This shows that the catalyst utilization is higher in the case of the membrane of the examples compared to the membrane of the comparative example. This increased catalyst utilization is believed to be due to improved contact between the catalyst and the electrolyte.

4 is a graph showing the cell voltage at 800 mA / cm ² , the charge transfer resistance at 0.8 V and the catalyst utilization rate according to the change in the amount of ions in the comparative examples and examples of the present invention. In FIG. 4, Comparative Examples and Examples are 0 (i.e., Comparative Example), 1x10E15 (i.e. Example 1), 1x10E16 (i.e. Example 2), 5x10E16 ( That is, it is shown by the change of an ion quantity like Example 3) and 1x10E17 (Example 4).

As can be seen from FIG. 4, the cell voltage at 800 mA / cm ² was the highest in Example 3 (process conditions of 5 × 10 ¹⁶ ions / cm ² ). In addition, Example 3 showed low charge transfer resistance and high Pt utilization of 46%. Therefore, it turned out that the surface treatment film | membrane by ion beam especially surface-treats with the ion beam of 5x10 <^16> ion / cm <^2> .

On the other hand, as the surface of the membrane becomes rougher, the valleys and peaks appearing on the surface show an abnormal structure. Such a rough surface provides more surface to which the catalyst and the polymer electrolyte can contact each other. As the amount of ions increases, the membrane surface is more affected and more peaks and valleys occur on that surface. Such membranes give a great change in the thickness of the coated catalyst layer when coated with a catalyst. However, when the surface of the membrane becomes excessively rough, catalyst particles fall into the valley and some of the hidden catalyst particles do not participate in the electrochemical reaction, so the utilization rate of Pt is lowered, resulting in low cell performance despite high surface roughness. Will be displayed.

Therefore, even if the surface of the membrane is irradiated with an ion beam, it is necessary to control the surface roughness up to a certain level by adjusting the ion amount density. As can be seen from the results of this experiment, the ion amount density that can improve the cell performance is ions. When the beam energy is 1 keV, it is preferably greater than 1 × 10 ¹⁵ ions / cm ^{2 and} 5 × 10 ¹⁶ ions / cm ² , most preferably 5 × 10 ¹⁶ ions / cm ² .

Catalyst for Cell Performance Loading  effect

Cathode catalyst loading with varying catalyst loadings of 0.1 to 0.55 mg-Pt / cm ² , respectively, for the membranes of Example 3 (5 × 10 ¹⁶ Ar ⁺ / cm ² , 1keV), which had the most improved membrane and cell performance of the comparative examples. The effect on positive cell performance was investigated.

5 is a graph measuring the performance of the unit cell using the membrane of Example 3 and Comparative Example of the present invention while varying the catalyst loading amount, Figure 5a shows the polarization curve in the comparative example, Figure 5b in Example 3 5C shows the cell voltage at 800 mA / cm ² according to the change of the catalyst loading in each of the membranes of Example 3 and Comparative Example. In the experiment with respect to FIG. 5, the anode catalyst loading amount was 0.3 mg-Pt / cm ² , and H ₂ / air was used. In FIG. 5C, the cell using the membrane of the comparative example is labeled “Untreated” and the cell using the membrane of Example 3 is labeled “Treated”.

As can be seen from FIG. 5a, in the case of the membrane of the comparative example, the current density gradually improved while the catalyst loading was increased from 0.1 mg-Pt / cm ² to 0.3 mg-Pt / cm ² , and the catalyst loading was 0.4 mg-Pt / cm ^2. The increase in current density slowed down. When the catalyst loading was further increased to 0.55 mg-Pt / cm ² , the decrease in performance due to the material transfer resistance was apparent in the high current density region due to the electrode thickness.

As shown in FIG. 5B, the membrane of Example 3 has a larger performance improvement at 0.1 to 0.2 mg-Pt / cm ^{2 than the} membrane of the comparative example of FIG. 5A, and even at 0.3 to 0.4 mg-Pt / cm ² . Performance was improved. In the case of the catalyst loading amount of 0.55 mg-Pt / cm ^2, the decrease in performance due to the material transfer resistance occurred faster than in the case of the cell manufactured with the membrane of the comparative example of FIG. 5A.

As can be clearly seen from FIG. 5C, the cell having the membrane of Example 3 has a higher performance than the cell having the membrane of the comparative example in all catalyst loading ranges except for a very high catalyst loading amount (0.55 mg-Pt / cm ² ). High.

6 is a graph showing the charge transfer resistance according to the change in the catalyst loading amount of the unit cell using the membrane of Example 3 and Comparative Example of the present invention. In the experiment with respect to FIG. 6, the anode catalyst loading amount was 0.3 mg-Pt / cm ² , and H ₂ / air was used. In FIG. 6, the cell using the membrane of the comparative example is labeled "Untreated" and the cell using the membrane of Example 3 is labeled "Treated".

As the Fig. As can be seen from 6, carried out in comparative example film when the amount of catalyst loading increased from 0.1 mg-Pt / cm ² to 0.2 mg-Pt / cm ² Comparative Example 3 R _p is as 1.17 Ωcm ² from 1.24 Ωcm ² In the case of the membrane of Example 3, the R _p was greatly reduced from 1.11 cm ³ to 0.79 cm ² . Furthermore, as the catalyst loading increased from 0.3 mg-Pt / cm ² to 0.5 mg-Pt / cm ² , R _p gradually decreased from 0.82 cm ² to 0.55 cm ² for the membrane of the comparative example. On the other hand, in Example 3, if the film in the amount of catalyst loading ^{0.3 mg-Pt / cm 2 0.59} Ωcm 2 near was a case where the catalyst loading amount of 0.4 mg-Pt / cm ² and ^{0.55 mg-Pt / cm 2 0.55} Ωcm 2 near Stabilized at

In short, it can be seen that in the catalyst loading amount before 0.55 mg-Pt / cm ^2, the cell with the membrane of Example 3 exhibits lower resistance to oxygen reduction and thus higher catalytic activity than the cell with the membrane of the comparative example.

On the other hand, when the catalyst loading amount of the cathode was fixed and the catalyst loading amount of the anode was changed, the same result as described above was obtained.

conclusion

Ar ⁺ was impinged on the Nafion 112 membrane by varying the ion mass density at 1 keV. As a result, the RMS roughness of the membrane surface was increased from 21 nm to 204 nm without changing the ion conductivity, non-hydrophilicity, and chemical structure of the membrane.

On the other hand, as the ion amount density was increased, the platinum catalyst utilization and cell performance increased, and the ion amount density decreased after showing the maximum value at 5 × 10 ¹⁶ ions / cm ² . This shows that the increase in the interface area between the electrode catalyst and the electrolyte membrane only increases to a certain level as the surface roughness of the membrane increases. If the surface roughness is increased beyond a certain level, the portion of the catalyst falls into the deep valleys of the roughened surface, and thus is isolated from the electrode, which results in a decrease in catalyst utilization and cell performance.

The performance of the unit cell using the Nafion 112 membrane of Comparative Example and Example 3 was measured while varying the catalyst loading, and as a result, the membrane of Example 3, which had been surface-treated except for 0.55 mg-Pt / cm ² , was High cell performance was shown, and the preferred catalyst loading was 0.1 mg-Pt / cm ² or more and less than 0.55 mg-Pt / cm ² .

On the other hand, the experiments on the catalyst loading amount showed that the catalyst loading amount can be reduced by impinging the ion beam on the membrane surface.

According to the present invention, it is possible to finely control the surface roughness of the electrolyte membrane without changing other performances of the electrolyte membrane, such as ionic conductivity, non-hydrophilicity characteristics and chemical properties of the surface, thereby achieving performance improvement of the fuel cell in which the electrolyte membrane is used.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications or variations without departing from the spirit and scope of the invention. Accordingly, the appended claims will include such modifications and variations as fall within the spirit of the invention.

Claims (13)

In the surface treatment method of the electrolyte membrane, The surface treatment method of the electrolyte membrane characterized by irradiating an ion beam to the surface of an electrolyte membrane, and treating the surface of an electrolyte membrane. The method of claim 1, wherein the method is The method of treating the surface of the electrolyte membrane, characterized in that to control the amount of ions irradiated per unit area while the ion beam energy is fixed at the time of ion beam irradiation to increase the performance of the cell in which the electrolyte membrane is used. The method of claim 2, wherein the method is The per 1 × 10 ¹⁵ ions / cm ² greater than 5 × 10 ¹⁶ ions / cm ² of the electrolyte membrane surface processing method, characterized in that at most the amount of ions emitted from the ion beam energy of 1keV state. The method of claim 3, wherein the method is The amount of ions irradiated per area is 5 × 10 ¹⁶ ions / cm ² in a state where the ion beam energy is 1 keV. The method according to any one of claims 1 to 4, wherein Ir ⁺ beam is irradiated as said ion beam, The surface treatment method of the electrolyte membrane characterized by the above-mentioned. The method according to any one of claims 1 to 4, wherein A surface treatment method of an electrolyte membrane, characterized by using a Nafion membrane as the electrolyte membrane. In the electrolyte membrane, The surface-treated electrolyte membrane, characterized in that the surface is irradiated with an ion beam. The method of claim 7, wherein the electrolyte membrane, The amount of ions irradiated per unit area in a state where the energy of the ion beam is 1 keV is greater than 1 × 10 ¹⁵ ions / cm ² 5 × 10 ¹⁶ ions / cm ² or less surface treated electrolyte membrane. The method of claim 8, wherein the electrolyte membrane, The surface of the electrolyte membrane, characterized in that the amount of ions irradiated per unit area in the state of the energy of the ion beam is 1keV 5 × 10 ¹⁶ ions / cm ² . The method of claim 9, wherein the electrolyte membrane, And the ion beam is an Ar ⁺ beam. The method of claim 10, wherein the electrolyte membrane, Surface-treated electrolyte membrane, characterized in that the electrolyte membrane is Nafion membrane. In the polymer electrolyte membrane fuel cell, A polymer electrolyte membrane fuel cell comprising the electrolyte membrane surface-treated according to any one of claims 7 to 11. The method of claim 12, The polymer electrolyte membrane fuel cell is a polymer electrolyte membrane fuel cell, characterized in that the catalyst loading amount for the electrolyte membrane is 0.1 mg-Pt / cm ² or more and less than 0.55 mg-Pt / cm ² .

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