JP2023079636A - Separator for solid polymer fuel cell and method for manufacturing the same - Google Patents

Abstract

To provide a separator for a solid polymer fuel cell which has excellent corrosion resistance and a low interface contact resistance value, and a method for manufacturing the same.SOLUTION: A method for manufacturing a separator 40 for a solid polymer fuel cell includes: a first nickel plating step of applying nickel plating to a metal plate 100 by immersing it in a first nickel plating solution containing hydrochloric acid and nickel chloride, thereby forming a first nickel layer 120 on the metal plate 100; and a second nickel plating step of applying nickel plating to the metal plate 100 having the first nickel layer 120 formed thereon by immersing it in a second nickel plating solution containing nickel sulfate and boric acid, thereby forming a second nickel layer 130 thicker than the first nickel layer 120 on the first nickel layer 120.SELECTED DRAWING: Figure 5

Description

TECHNICAL FIELD The present invention relates to a polymer electrolyte fuel cell separator and a manufacturing method thereof.

Polymer electrolyte fuel cells are highly effective in reducing CO ₂ , and are used as power sources for households, automobiles, and the like.

A polymer electrolyte fuel cell includes a negative electrode, a positive electrode, and a separator provided on these electrodes. Since the negative electrode reacts with hydrogen and the positive electrode reacts with water and oxygen, their surroundings become strongly acidic or alkaline. Therefore, the separator needs to be easily corroded by acid or alkali and have excellent corrosion resistance. In order to supply the power generated by the polymer electrolyte fuel cell to an external circuit with low loss, the interfacial contact resistance of the separator is preferably low.

Patent Literature 1 discloses a corrosion-resistant separator used in polymer electrolyte fuel cells. This separator has a structure in which an aluminum substrate, a copper layer, a tin layer, and a metal layer made of titanium, vanadium, or the like are laminated.

JP 2011-198573 A

The separator disclosed in Patent Literature 1 has a problem that the interfacial contact resistance value is increased because the surface is corroded, the surface material structure is changed, and the conductivity is lost.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polymer electrolyte fuel cell separator having excellent corrosion resistance and low interfacial contact resistance, and a method for producing the same.

The present invention is as follows.
[1] A method for producing a polymer electrolyte fuel cell separator according to the present invention comprises: immersing a metal plate in a first nickel plating solution containing hydrochloric acid and nickel chloride to apply nickel plating; and immersing the metal plate having the first nickel layer in a second nickel plating solution containing nickel sulfate and boric acid. and a second nickel plating step of nickel plating to form a second nickel layer on the first nickel layer that is thicker than the first nickel layer.

[2] The first nickel plating solution has a hydrochloric acid concentration of 2.0 mol/L or more and 3.5 mol/L or less, and the first nickel plating solution has a nickel chloride concentration of 0.5 mol/L. 2.0 mol/L or less, the second nickel plating solution has a nickel sulfate concentration of 0.5 mol/L or more and 2.0 mol/L or less, and the second nickel plating solution has a boric acid concentration of , 0.10 mol/L or more and 1.50 mol/L or less.

[3] The temperature of the first nickel plating solution when the metal plate is immersed in the first nickel plating solution is 15° C. or higher and 50° C. or lower, and the second nickel plating solution has the above The temperature of the second nickel plating solution when immersing the metal plate having the first nickel layer formed thereon may be 45° C. or higher and 65° C. or lower.

[4] The first nickel plating step is an electrolytic plating step, the current density is 0.15 A/cm ² or more and 0.4 A/cm ² or less, and the second nickel plating step is , an electroplating process, and the current density is 0.15 A/cm ² or more and 0.4 A/cm ² or less.

[5] The metal plate may be made of one selected from the group consisting of stainless steel, aluminum, magnesium, and titanium.

[6] A polymer electrolyte fuel cell separator according to the present invention comprises a metal plate, a first nickel layer formed on the metal plate, and a layer formed on the first nickel layer. a second nickel layer, wherein the thickness of the first nickel layer is 0.01 μm or more and 1.0 μm or less, the thickness of the second nickel layer is 2.0 μm or more, and corrosion is prevented The current density is 0.001 μA/cm ² or more and 1.100 μA/cm ² or less, and the interfacial contact resistance value is 0.01 mΩ·cm ² or more and 1.00 mΩ·cm ² or less.

Further, the polymer electrolyte fuel cell separator according to [7] and [6] has an interfacial contact resistance value of 10.0 mΩ·cm ² or less after being immersed in a 1 mol/L sodium hydroxide aqueous solution at 70°C. be.

[8] The metal plate may be made of one selected from the group consisting of stainless steel, aluminum, magnesium, and titanium.

ADVANTAGE OF THE INVENTION According to this invention, the separator for polymer electrolyte fuel cells which is excellent in corrosion resistance and has a low interfacial contact resistance value, and its manufacturing method can be provided.

1 is a schematic diagram of a plating apparatus used in a first nickel plating process according to an embodiment of the invention; FIG. It is a schematic diagram of a plating processing apparatus used in the second nickel plating processing step according to the embodiment of the present invention. FIG. 4 is a schematic diagram of another plating apparatus that can be used in the second nickel plating process according to the embodiment of the invention; 1 is a schematic top view of a polymer electrolyte fuel cell separator; FIG. 5 is a cross-sectional view taken along line VV of FIG. 4; FIG. 1 is a schematic cross-sectional view of an anion exchange polymer electrolyte fuel cell; FIG. (a) shows the structure of the polymer electrolyte fuel cell separator according to the example and the comparative example and the Tafel plot (the relationship between the logarithmic value of the current changed by the oxidation-reduction reaction of the polymer electrolyte fuel cell separator and the potential) (b) shows the relationship between the corrosion potential, corrosion current density, anode Tafel constant, cathode Tafel constant, and cathode Tafel constant of polymer electrolyte fuel cell separators according to Examples and Comparative Examples. and polarization resistance. (a) to (d) are diagrams showing contact angles of polymer electrolyte fuel cell separators according to Examples and Comparative Examples. 4 is a graph showing the relationship between the configuration of polymer electrolyte fuel cell separators and interfacial contact resistance values according to Examples and Comparative Examples. (a) is a diagram showing the relationship between the energization time and the Tafel plot in the second nickel plating treatment process of the polymer electrolyte fuel cell separator according to the example and the comparative example, and (b) is a diagram showing the relationship between the Tafel plot FIG. 3 is a diagram showing the corrosion potential, corrosion current density, anode Tafel constant, and cathode Tafel constant of the polymer electrolyte fuel cell separator according to the example. 4 is a graph showing the relationship between the energization time and the interfacial contact resistance value in the second nickel plating process of the polymer electrolyte fuel cell separators according to Examples and Comparative Examples. (a) is a diagram showing the relationship between the treatment temperature and Tafel plot in the second nickel plating treatment step of the polymer electrolyte fuel cell separator according to the example and the comparative example, and (b) is a diagram showing the relationship between the treatment temperature and the Tafel plot. FIG. 3 is a diagram showing the corrosion potential, corrosion current density, anode Tafel constant, and cathode Tafel constant of the polymer electrolyte fuel cell separator according to the example. 4 is a graph showing the relationship between the treatment temperature and the interface contact resistance value in the second nickel plating treatment step of polymer electrolyte fuel cell separators according to Examples and Comparative Examples. (a) shows the potential of the metal plate with respect to the reference electrode (silver/silver chloride electrode (Ag/AgCl electrode)) and Tafel in the second nickel plating process of the polymer electrolyte fuel cell separator according to the example and the comparative example. FIG. 10B is a diagram showing the relationship between plots, and (b) shows the corrosion potential, corrosion current density, anode Tafel constant, and cathode Tafel constant of separators for polymer electrolyte fuel cells according to Examples and Comparative Examples. It is a diagram. Potential and interfacial contact resistance of the metal plate with respect to the reference electrode (silver/silver chloride electrode (Ag/AgCl electrode)) in the second nickel plating process of the polymer electrolyte fuel cell separators according to Examples and Comparative Examples. is a graph showing the relationship of (a) is a diagram showing the relationship between the hydrochloric acid concentration of the first nickel plating solution and the Tafel plot in the first nickel plating process of the polymer electrolyte fuel cell separator according to the example and the comparative example; b) is a diagram showing the corrosion potential, corrosion current density, anode Tafel constant, and cathode Tafel constant of separators for polymer electrolyte fuel cells according to Examples and Comparative Examples. 4 is a graph showing the relationship between the hydrochloric acid concentration of the first nickel plating solution and the interfacial contact resistance value in the first nickel plating treatment step for polymer electrolyte fuel cell separators according to Examples and Comparative Examples.

EMBODIMENT OF THE INVENTION Hereinafter, the form (only henceforth "embodiment") for implementing this invention is demonstrated in detail. The following embodiments are exemplifications for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of the gist thereof.

[Manufacturing method of polymer electrolyte fuel cell separator]
A method for manufacturing a polymer electrolyte fuel cell separator according to an embodiment comprises: immersing a metal plate in a first nickel plating solution containing hydrochloric acid and nickel chloride to apply nickel plating; The metal plate having the first nickel layer formed thereon is immersed in a first nickel plating treatment step for forming a nickel layer, and a second nickel plating solution containing boric acid and nickel sulfate to perform nickel plating. and a second nickel plating step of forming a second nickel layer on the one nickel layer, the second nickel layer being thicker than the first nickel layer.

The details of each processing step will be described below in order.
(First nickel plating process)
A plating apparatus 10 is used in the first nickel plating process. The plating apparatus 10 includes a plating bath section 150 and a control measurement section 160, as shown in FIG.

The plating bath section 150 supplies a first nickel plating solution 153 for forming a first nickel layer on a metal plate (work) 100 as a raw material in order to form a polymer electrolyte fuel cell separator. It includes a plating bath 151 to accommodate and a heater 152 to heat the plating bath 151 .

A plating bath 151 is filled with a first nickel plating solution 153 . A nickel plate 140 for eluting nickel ions, a metal plate 100 to be nickel-plated, and a thermometer 167 are immersed in the first nickel plating solution 153 .

The metal plate 100 is a metal plate having a rectangular shape in a plan view and serving as a material for a polymer electrolyte fuel cell separator. Metal plate 100 is made of one selected from the group consisting of stainless steel, aluminum, magnesium, and titanium. In addition, although the shape of the metal plate 100 of the embodiment has been described as being rectangular in plan view, the shape can be appropriately selected. The thickness of the metal plate 100 can be selected as appropriate.

The nickel plate 140 supplies nickel ions into the first nickel plating solution 153 . From the viewpoint of efficiently forming the first nickel layer on the metal plate 100, the purity of nickel is preferably 99% or more. The thickness and shape of the nickel plate 140 can be selected as appropriate.

The heater 152 is not particularly limited as long as it can heat the plating bath 151, and examples thereof include an electric heater, a water bath for heating the entire plating bath 151, an oil bath, and the like.

Control measurement unit 160 includes measurement unit 161 , power supply unit 162 , and control unit 163 .

The measurement unit 161 takes in measurement data of the thermometer 167 and the ammeter 168 .

A thermometer 167 measures the temperature of the first nickel plating solution 153 . Ammeter 168 measures the current flowing through power supply unit 162 , nickel plate 140 , metal plate 100 , and power supply unit 162 in that order.

The power supply unit 162 uses the power from the external power supply 170 to supply power to the heater 152 according to the control of the control unit 163 . In addition, power supply section 162 uses power from external power supply 170 to control the voltage applied between metal plate 100 and nickel plate 140 according to the control of control section 163 .

The power supply unit 162 includes, for example, a first DC/DC converter that converts the voltage from the external power supply 170 into a voltage to be applied to the heater 152 under the control of the control unit 163, and the external power supply 170 under the control of the control unit 163. and a second DC/DC converter for converting the voltage into a voltage applied between the metal plate 100 and the nickel plate 140 .

The external power supply 170 is composed of, for example, a battery, an AC adapter, etc., and supplies power to the power supply unit 162 .

The control unit 163 is configured by a computer or the like. Measurement data of the thermometer 167 and the ammeter 168 are supplied to the control unit 163 via the measurement unit 161 .

Based on the temperature measured by the thermometer 167, the control unit 163, for example, by PID (Proportional-Integral-Differentia) control, keeps the temperature of the first nickel plating solution 153 substantially constant at, for example, 45° C. or higher and 65° C. or lower. The power supply unit 162 is controlled to maintain the temperature. The power supply unit 162 adjusts the voltage supplied to the heater 152 under the control of the control unit 163 to maintain the temperature of the first nickel plating solution 153 at a substantially constant value.

In addition, based on the measured value of the ammeter 168, the control unit 163 adjusts the current per unit area flowing through the metal plate 100 to 0.15 A/cm ² or more and 0.4 A/cm suitable for plating, for example, by PID control. The power supply unit 162 is controlled so as to maintain a substantially constant value of ² or less. Power supply unit 162 adjusts the voltage applied between metal plate 100 and nickel plate 140 under the control of control unit 163 to adjust the current density of metal plate 100 .

The first nickel plating solution 153 is a solution for depositing nickel ions on the metal plate 100 . The first nickel plating solution 153 is an aqueous solution containing hydrochloric acid (HCl) and nickel chloride (NiCl ₂ ). From the viewpoint of efficiently forming the first nickel layer on the metal plate 100, the concentration of hydrochloric acid in the first nickel plating solution 153 is preferably 2.0 mol/L or more and 3.5 mol/L or less. 0 mol/L or more and 3.5 mol/L or less is more preferable. From the viewpoint of efficiently forming the first nickel layer on the metal plate 100, the nickel chloride concentration is preferably 0.5 mol/L or more and 2.0 mol/L or less, and 0.5 mol/L or more. It is more preferably 5 mol/L or less.

The first nickel plating solution 153 is heated by the heater 152 and maintained at, for example, 15° C. or higher and 50° C. or lower, preferably 20° C. or higher and 35° C. or lower.

Next, the process of forming the first nickel layer on the metal plate 100 by the plating processing apparatus 10 will be described.

As shown in FIG. 1, a metal plate 100 and a nickel plate 140 corresponding to works are immersed in a first nickel plating solution 153 .

In this state, the control unit 163 activates the power supply unit 162 to apply a negative voltage to the metal plate 100 and a positive voltage to the nickel plate 140 . Then, the nickel atoms in the nickel plate 140 emit electrons, become nickel ions, and are eluted into the first nickel plating solution 153 . The emitted electrons flow into the metal plate 100 via the power supply section 162 and become excess electrons. The eluted nickel ions are positively charged, attracted to the negatively charged metal plate 100, combined with excess electrons of the metal plate 100, and deposited on the surface. A first nickel layer is thus formed on the metal plate 100 .

During the process, the controller 163 controls the heater 152 via the power supply 162 to keep the temperature of the first nickel plating solution 153 constant between 15° C. and 50° C., preferably between 20° C. and 35° C. control the calorific value of In addition, the control unit 163 determines that the current value measured by the ammeter 168 during the process corresponds to the current per unit area flowing through the metal plate 100 of 0.15 A/cm ² or more and 0.4 A/cm ² or less. The voltage applied between the metal plate 100 and the nickel plate 140 is controlled via the power supply unit 163 so that the voltage is substantially constant.

The control unit 163 counts the energization time, and when the count value reaches the timing when the first nickel layer reaches a predetermined thickness of 0.01 μm or more and 1.0 μm or less, the power supply unit 162 is controlled. to turn off the power. This stops the growth of the first nickel layer.

The growth time of the first nickel layer, that is, the energization time depends on the current density of the current flowing through the metal plate 100, the temperature of the first nickel plating solution 153, and the concentration of hydrochloric acid in the first nickel plating solution 153. The concentration of nickel chloride varies depending on the thickness of the nickel layer to be formed. Therefore, the energization time is obtained in advance by experiment, simulation, or the like, and the energization is stopped when the energization is performed for this energization time. For example, the first nickel plating solution 153 has a hydrochloric acid concentration of 3.5 mol/L and a nickel chloride concentration of 1.0 mol/L, the size of the metal plate 100 is 10×20 mm, and the current is 0.35 A. Sometimes, it is preferably 30 seconds or more and 120 seconds or less, more preferably 40 seconds or more and 70 seconds or less.

The metal plate 100 that has undergone the first nickel plating process described above has a first nickel layer 120 formed on the metal plate 100 .

Nickel plating in the first nickel plating process is also called strike plating.

(Second nickel plating process)
Next, the second nickel plating step of the method for manufacturing a polymer electrolyte fuel cell separator according to the embodiment will be described.

A plating apparatus 20 is used in the second nickel plating process. The plating apparatus 20 is substantially the same as the plating apparatus 10 except that the first nickel plating solution 153 in the plating bath section 150 is replaced with the second nickel plating solution 154 .

The second nickel plating solution 154 is a solution for depositing nickel ions on the first nickel layer 120, and is _an aqueous solution containing nickel sulfate ( _NiSO4 ) and boric acid ( _H3BO3 ). is. From the viewpoint of efficiently forming the second nickel layer on the first nickel layer 120, the nickel sulfate concentration is preferably 0.5 mol/L or more and 2.0 mol/L or less, and 0.75 mol/L. It is more preferable that it is more than or equal to 1.25 mol/L or less. From the viewpoint of efficiently forming the second nickel layer on the first nickel layer 120, the boric acid concentration is preferably 0.10 mol/L or more and 1.50 mol/L or less, and 0.25 mol/L. More preferably, it is 0.75 mol/L or less.

The control unit 163 controls the power supply unit 162 so as to maintain the temperature of the second nickel plating solution 154 at a substantially constant temperature of, for example, 45°C or higher and 65°C or lower.

Further, the control unit 163 sets the current flowing through the power supply unit 162, the nickel plate 140, the metal plate 100, and the power supply unit 162 in this order so that the current per unit area flowing through the metal plate 100 is 0.15 A/cm ² or more and 0.4 A. /cm ² or less.

Next, the process of forming the second nickel layer on the first nickel layer 120 by the plating processing apparatus 20 will be described.

The metal plate 100 having the first nickel layer 120 formed thereon and the nickel plate 140 are immersed in a second nickel plating solution 154 .

In this state, the control unit 163 activates the power supply unit 162 to apply a negative voltage to the metal plate 100 and a positive voltage to the nickel plate 140 . Then, the nickel atoms in the nickel plate 140 emit electrons, become nickel ions, and are eluted into the second nickel plating solution 154 . The eluted nickel ions are attracted to the negatively charged metal plate 100 , combine with excess electrons on the metal plate 100 , and deposit on the first nickel layer 120 . A second nickel layer is thereby formed on the first nickel layer 120 .

During the process, the controller 163 controls the heater 152 via the power supply 162 to keep the temperature of the second nickel plating solution 154 constant between 45° C. and 65° C., preferably between 55° C. and 60° C. control the calorific value of In addition, the control unit 163 determines that the current value measured by the ammeter 168 during the process corresponds to the current per unit area flowing through the metal plate 100 of 0.15 A/cm ² or more and 0.4 A/cm ² or less. The voltage applied between the metal plate 100 and the nickel plate 140 is controlled via the power supply unit 163 so that the voltage is substantially constant.

The control unit 163 controls the power supply unit 162 to stop energization at the timing when the second nickel layer reaches a predetermined thickness of 2.0 μm or more. This stops the growth of the second nickel layer.

The growth time of the second nickel layer, that is, the energization time depends on the current density of the current flowing through the metal plate 100, the temperature of the second nickel plating solution 154, and the nickel sulfate in the second nickel plating solution 154 ( NiSO ₄ ) and boric acid (H ₃ BO ₃ ) concentrations. Therefore, it is determined in advance by experiments, simulations, or the like. For example, the second nickel plating solution 154 has a nickel sulfate concentration of 2.0 mol/L and a boric acid concentration of 0.75 mol/L, the size of the metal plate 100 is 10×20 mm, and the current is 0.35 A. At one time, it is preferably 1000 seconds or more and 1400 seconds or less, more preferably 1100 seconds or more and 1300 seconds or less.

In this way, as shown in FIGS. 4 and 5, the metal plate 100, the first nickel layer 120 formed on the metal plate 100, and the first nickel layer 120 are formed in the shape of a rectangular flat plate. Thus, a polymer electrolyte fuel cell separator 40 having a second nickel layer 130 formed on the surface is obtained. Since the polymer electrolyte fuel cell separator 40 sequentially performs the first nickel plating process and the second nickel plating process, the adhesion between the metal plate 100 and the first nickel layer 120, and Adhesion between the first nickel layer 120 and the second nickel layer 130 is enhanced. In addition, since the first nickel layer 120 prevents corrosion of the metal plate 100 by an acid solution or an alkaline solution, the polymer electrolyte fuel cell separator 40 is excellent in corrosion resistance. In addition, since the first nickel layer 120 activates the surface of the metal plate 100, the second nickel layer 130 is formed more densely than the first nickel layer 120, and the interfacial contact resistance value is low. .

In the first nickel plating process, a metal plate coated with a noble metal such as platinum (Pt) can be used instead of the nickel plate 140 . In this case, nickel chloride (NiCl ₂ ) should be added to the first nickel plating solution 153 periodically to keep the nickel ions present in the first nickel plating solution 153 constant.

Also in the second nickel plating process, a metal plate coated with a noble metal such as platinum (Pt) can be used instead of the nickel plate 140 . In this case, nickel sulfate (NiSO ₄ ) should be added to the second nickel plating solution 154 periodically to keep the nickel ions present in the second nickel plating solution 154 constant.

The first nickel plating process may further include a roughening process for roughening the surface of the metal plate 100 before the metal plate 100 is immersed in the first nickel plating solution 153 . By roughening the surface of the metal plate 100, the adhesion between the first nickel layer and the metal plate 100 is improved. Methods for roughening the surface of the metal plate 100 include, for example, a method of roughening the surface by spraying small grains of sand onto the surface of the metal plate 100 and a method of polishing the surface of the metal plate 100 with fine sandpaper. Examples of fine sandpaper counts include C800 (#800) and C2000 (#2000).

From the viewpoint of removing oil from the surface of the metal plate 100, the surface of the metal plate 100 may be washed with an organic solvent such as acetone or methyl ethyl ketone before being immersed in the first nickel plating solution 153. This facilitates formation of nickel plating on the metal plate 100 . In addition, ultrasonic waves are preferably used for cleaning, and when a roughening treatment step is included, cleaning is preferably performed after the roughening treatment step.

Before immersing the metal plate 100 in the first nickel plating solution 153, the metal plate 100 is immersed in an aqueous solution having a hydrochloric acid concentration of 1.0 mol/L, and then ethanol and water are mixed at a volumetric ratio of 50:50. may be washed with a solution containing Thereby, the surface of the metal plate 100 is chemically modified, and the adhesion between the first nickel layer 120 and the metal plate 100 is improved. When this treatment is performed, it is more preferable to perform it immediately before the first nickel plating treatment step.

Alternative solutions to the second nickel plating solution 154 include an aqueous solution containing nickel(II) chloride, nickel sulfate, and nickel sulfamate, and an aqueous solution containing nickel(II) chloride, nickel sulfate, and nickel(II) nitrate. , an aqueous solution containing nickel(II) chloride, nickel sulfamate and boric acid.

Although the temperature and current are constant in the first and second nickel plating processes of the embodiment, the temperature and current may be changed on the time axis.

In the embodiment, the second nickel plating process is explained using electrolytic plating as an example, but the second nickel layer may be formed on the first nickel layer 120 by electroless nickel plating. A plating processing apparatus 30 for electroless nickel plating includes, for example, a plating bath section 159 and a thermometer 320, as shown in FIG.

The plating bath section 159 includes a plating bath 158 containing a third nickel plating solution 310 for further forming a second nickel layer on the first nickel layer 120 formed on the metal plate 100 . , and a heater 157 for heating the plating bath 158 .

Plating bath 158 contains a third nickel plating solution 310 . A metal plate 100 having a first nickel layer 120 formed thereon and a thermometer 320 for measuring the temperature of the third nickel plating solution 310 are immersed in the third nickel plating solution 310 .

A heater 157 heats the plating bath 158 .

The third nickel plating solution 310 is an aqueous solution containing nickel ions and hypophosphite. The third nickel plating solution 310 contains nickel sulfate and hypophosphite because the concentrations of nickel ions and hypophosphite in the aqueous solution decrease as the reaction in which nickel deposits on the first nickel layer 120 progresses. Preference is given to adding phosphate and sodium hydroxide as a pH adjuster.

In the second nickel plating process using the plating apparatus 30, the second nickel layer is formed on the first nickel layer 120 as follows. When the metal plate 100 having the first nickel layer 120 formed thereon is immersed in a third nickel plating solution 310 containing nickel ions and, for example, hypophosphorous acid as a reducing agent, electrons are released from the hypophosphorous acid. released. These electrons combine with nickel ions, and nickel as metal is deposited on the first nickel layer 120 . A second nickel layer is thereby formed on the first nickel layer 120 .

The time for immersing the metal plate 100 having the first nickel layer 120 formed thereon in the third nickel plating solution 310 is from 60 minutes to 120 minutes from the viewpoint of making the second nickel layer thicker than the first nickel layer. It is preferably 80 minutes or longer and 100 minutes or shorter.

From the viewpoint of efficiently forming the second nickel layer on the first nickel layer 120, the temperature of the third nickel plating solution 310 is preferably 70° C. or higher and 90° C. or lower.

Alternative solutions to the third nickel plating solution 310 include aqueous solutions containing nickel sulfate, dimethylamine borane as a reducing agent, trisodium citrate as an oxidizing agent, and sodium hydroxide as a pH adjusting agent. . The conditions for nickel plating in this aqueous solution are a temperature of 70° C. and a pH of 8-10.

[Separator for polymer electrolyte fuel cell]
Next, the polymer electrolyte fuel cell separator 40 manufactured by the manufacturing method described above will be described. The polymer electrolyte fuel cell separator 40 is a proton exchange type polymer electrolyte fuel cell separator using a proton exchange type polymer electrolyte membrane, and an anion exchange type separator using an anion exchange type polymer electrolyte membrane. It can be used as a separator for polymer electrolyte fuel cells. Since the polymer electrolyte fuel cell separator has a second nickel layer thicker than the first nickel layer and has corrosion resistance, it can be suitably used as a separator for an anion exchange polymer electrolyte fuel cell. .

An anion exchange polymer electrolyte fuel cell 50 shown in FIG. 6 will be described below as an example. The anion exchange polymer electrolyte fuel cell 50 includes an anode electrode 400, a cathode electrode 420, a polymer electrolyte membrane 410, a polymer electrolyte fuel cell separator 41, and a polymer electrolyte fuel cell separator 42. , provided.

The anode electrode 400 has a configuration in which an anode catalyst layer 43 and a gas diffusion layer 45 are laminated in order from the polymer electrolyte membrane 410 .

The cathode electrode 420 has a configuration in which a cathode catalyst layer 44 and a gas diffusion layer 46 are laminated in order from the polymer electrolyte membrane 410 .

An example of the anode catalyst layer 43 is 20% Platinum on Vulcan XC-72R (manufactured by FC Catalyst).

An example of the cathode catalyst layer 44 is 20% Platinum on Vulcan XC-72R (manufactured by FC Catalyst).

Examples of the gas diffusion layer 45 and the gas diffusion layer 46 include a porous sheet (carbon paper) made of carbon fiber, specifically TGP-H-030 (manufactured by Toray Industries, Inc.), TGP-H-060 ( manufactured by Toray Industries, Inc.).

An example of the polymer electrolyte membrane 410 is FFA3 anion exchange membrane (manufactured by Fumatech).

Polymer electrolyte fuel cell separator 41 and polymer electrolyte fuel cell separator 42
are each composed of a polymer electrolyte fuel cell separator 40 . However, concave grooves for flowing the fuel 431 and the fuel 433 are formed on the contact surface with the adjacent anode electrode 400 or cathode electrode 420 .

Next, the mechanism by which the anion exchange polymer electrolyte fuel cell 50 generates an electromotive force will be described.

On the cathode electrode 420 side, a fuel 431 such as oxygen (O ₂ ) or water (H ₂ O) supplied from the outside flows through a fuel flow (not shown) provided in the thickness direction of the polymer electrolyte fuel cell separator 42 . It passes through the path, reaches the gas diffusion layer 46 side, passes through the recessed grooves formed in the polymer electrolyte fuel cell separator 42, and spreads over the entire main surface of the gas diffusion layer 46. 46 to reach the cathode catalyst layer 44 . Fuel 431 (oxygen and water) undergoes the following reactions in cathode catalyst layer 44 .

O ₂ +2H ₂ O+4e ⁻ →4OH ⁻
Here, e ⁻ represents an electron and OH ⁻ represents a hydroxide ion.
This reaction produces hydroxide ions. The generated hydroxide ions move through the polymer electrolyte membrane 410 and reach the anode catalyst layer 43 . Also, the remaining fuel 432 that has not reacted is discharged outside the anion exchange polymer electrolyte fuel cell 50 .

On the anode electrode 400 side, a fuel 433 such as hydrogen (H ₂ ) supplied from the outside passes through a fuel channel (not shown) provided in the thickness direction of the polymer electrolyte fuel cell separator 41, and gas diffusion occurs. The layer 45 side is reached. The fuel 433 passes through the concave grooves formed in the polymer electrolyte fuel cell separator 41 , spreads over the entire main surface of the gas diffusion layer 45 , passes through the gas diffusion layer 45 , and reaches the anode catalyst layer 43 . reach. The fuel 433 reaching the anode catalyst layer 43 and the hydroxide ions reaching the anode catalyst layer 43 from the cathode catalyst layer 44 via the polymer electrolyte membrane 410 react in the anode catalyst layer 43 as follows.

2H ₂ +4OH ⁻ →4H ₂ O+4e ⁻
This reaction generates water and electrons. The electrons flow in direction 440 and return to anion exchange polymer electrolyte fuel cell 50 via external circuit 430 to repeat the reactions described above. The remaining fuel 434 that has not reacted with the produced water is discharged out of the anion exchange polymer electrolyte fuel cell 50 .

Thus, the polymer electrolyte fuel cell separator 42 facing the cathode electrode 420 and the polymer electrolyte fuel cell separator 41 facing the anode electrode 400 are located inside the anion exchange polymer electrolyte fuel cell 50 . It is easily corroded because it comes into contact with the hydroxide ions generated in the

In the polymer electrolyte fuel cell separator 40 (41, 42) according to the embodiment, a first nickel layer 120 and a second nickel layer 130 are plated on a metal plate 100 in this order. Since the second nickel layer 130 is thicker than the first nickel layer 120, it is corrosion resistant. Therefore, the polymer electrolyte fuel cell separator 40 according to the embodiment is a polymer electrolyte fuel cell separator suitable for the anion exchange polymer electrolyte fuel cell 50 .

Further, in the polymer electrolyte fuel cell separator 40 according to the embodiment, plating layers are formed in the order of the first nickel layer 120 and the second nickel layer 130 on the metal plate 100, and the first nickel layer Since the second nickel layer 130 is thicker than the layer 120, the interfacial contact resistance value is as low as 0.01 mΩ·cm ² or more and 1.00 mΩ·cm ² or less. Therefore, the power generated by the anion exchange polymer electrolyte fuel cell 50 can be supplied to the external circuit 430 with low loss.

Further, the thickness of the first nickel layer 120 constituting the polymer electrolyte fuel cell separator 40 is 0.1 μm or more and 1.0 μm or less, and the second nickel layer 120 formed on the first nickel layer 120 has a thickness of 0.1 μm or more and 1.0 μm or less. Since the thickness of the nickel layer 130 is 2.0 μm or more, the corrosion current density of the polymer electrolyte fuel cell separator 40 is 0.001 μA/cm ² or more and 1.100 μA/cm ² or less, and the interfacial contact resistance value is 0.01 mΩ·cm ² or more and 1.00 mΩ·cm ² or less, and the interfacial contact resistance value after immersing the polymer electrolyte fuel cell separator 40 in a 1 mol/L sodium hydroxide aqueous solution at 70° C. is 10.0 mΩ·cm 2 . cm ² or less. Here, the temperature and concentration of the aqueous sodium hydroxide solution reproduce the situation in the presence of alkali inside the anion exchange polymer electrolyte fuel cell.

As described above, the polymer electrolyte fuel cell separator 40 according to the embodiment has excellent corrosion resistance and a low interfacial contact resistance value. Further, the polymer electrolyte fuel cell separator 40 can be provided by the method for manufacturing a polymer electrolyte fuel cell separator according to the embodiment.

The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is in no way limited by the following examples.

(Example p4)
A sample of Example p4 was produced by the following procedure. First, a stainless steel plate was prepared as a metal plate constituting the sample of Example p4 and subjected to pretreatment. Next, the stainless plate was plated in the order of the first nickel plating treatment and the second nickel plating treatment to obtain a sample of Example p4.

(1) Pretreatment A stainless steel plate (1 mm thick, SS304) was prepared as a metal plate, cut into a square of 10×20 mm, and the surface thereof was sanded with sandpaper No. C800. After that, it was washed with acetone and methanol. Next, in order to remove the oxide film formed on the surface of the stainless plate, the stainless plate was immersed in a 1 mol/L hydrochloric acid aqueous solution for 10 minutes. Then, it was washed for 15 minutes using an ultrasonic cleaner (US-1R manufactured by ASONE) and dried using a vacuum constant temperature dryer (VOM-1000 manufactured by Tokyo Rikakikai Co., Ltd.). This stainless steel plate was used as a stainless plate after pretreatment.

(2) First nickel plating treatment The stainless plate after pretreatment and the nickel plate are applied to a three-electrode (counter electrode, reference electrode, working electrode) system of an electrochemical analyzer (701C manufactured by BAS) as a control measuring instrument. It was connected and immersed in a container filled with an aqueous solution containing 3.5 mol/L hydrochloric acid (HCl) and 1.0 mol/L nickel chloride (NiCl ₂ ). Here, a nickel plate was used as a counter electrode, a silver/silver chloride electrode (Ag/AgCl electrode) was used as a reference electrode, and a stainless steel plate was used as a working electrode. Next, the pretreated stainless steel plate was nickel-plated under the conditions that the temperature of the aqueous solution was 23° C., the current was −0.35 A, the potential of the stainless steel plate (working electrode) with respect to the reference electrode was −1.0 V, and the duration was 60 seconds. . Thereafter, the stainless plate was washed with deionized water to obtain a stainless steel plate having a first nickel layer formed thereon. Further, when the thickness of the first nickel layer was measured with a color 3D laser microscope VK-9700 (manufactured by Keyence Corporation), it was 0.1 μm or more and 1.0 μm or less. In addition, in order to measure the potential of the stainless steel plate, the first nickel plating treatment was performed by connecting to a three-electrode system. In addition, the current was set at −0.35 A because of the 3-electrode (counter electrode, reference electrode, working electrode) system.

(3) Second nickel plating treatment The stainless steel plate and the nickel plate subjected to the first nickel plating treatment are used as a control measuring instrument for an electrochemical analyzer (701C manufactured by BAS) with three electrodes (counter electrode, reference electrode, working electrode). The electrode) was connected to a system and immersed in a container filled with an aqueous solution containing 1 mol/L nickel sulfate (NiSO ₄ ) and 0.5 mol/L boric acid (H ₃ BO ₃ ). Here, a nickel plate was used as a counter electrode, a silver/silver chloride electrode (Ag/AgCl electrode) was used as a reference electrode, and a stainless steel plate was used as a working electrode. Next, when the temperature of the aqueous solution reached 60° C., the first nickel plating was performed under the conditions of -0.35 A current, -1.0 V potential of the stainless steel plate (working electrode) with respect to the reference electrode, and 1200 seconds. Nickel plating was applied to the stainless steel plate. Then, it was washed with ultrapure water and dried in a vacuum constant temperature dryer at 23° C. for 120 minutes to obtain a stainless steel plate having a second nickel layer formed on the first nickel layer. This was used as a sample. Further, when the total thickness of the first nickel layer and the second nickel layer was measured with a step meter DEKTAK 3030 (manufactured by Dektak), it was 17.0 μm. In addition, in order to measure the potential of the stainless steel plate, a second nickel plating treatment was performed by connecting to a three-electrode system. In addition, the current was set at −0.35 A because of the 3-electrode (counter electrode, reference electrode, working electrode) system.

(Comparative Example p1 to Comparative Example p3, and Comparative Example p24 to Comparative Example p31)
The samples of Comparative Examples p1 to p3 and Comparative Examples p24 to p31 were subjected to the same conditions as in Example p4 according to the conditions of the first nickel plating treatment and the conditions of the second nickel plating treatment shown in Tables 1 and 2. It was produced according to the production procedure.

Next, the method for measuring the corrosion current density of the sample, the interfacial contact resistance value between the sample and the carbon paper, and the contact angle of the sample will be described.

<Corrosion current density>
The corrosion current density was measured using a three-electrode system of a high-performance electrochemical measurement system (Bio-logic VMP300). A saturated calomel electrode saturated with potassium chloride (KCl) (SCE electrode), or silver/silver chloride, using a platinum mesh as the counter electrode, for the three electrodes (counter electrode, reference electrode, working electrode) that make up a three-electrode system. The electrode (Ag/AgCl electrode) was used as the reference electrode and the sample as the working electrode. The measurement was performed by setting the potential scan rate to 1 mV/s while each electrode was immersed in a container filled with a 1 mol/L sodium hydroxide aqueous solution at 70°C. The numerical value of the corrosion current density was read using analysis software EC-lab manufactured by Bio-logic.

<Interfacial contact resistance value (ICR)>
The interfacial contact resistance value was measured using a 2450 source meter (manufactured by Keithley) and a 2182A nanovoltmeter (manufactured by Keithley). First, carbon paper (TGP-H-030 manufactured by Toray Industries, Inc.) was sandwiched between a copper plate (thickness 1 mm) and the sample, and then a current of 1 mA was applied with a load of 1.4 MPa in total pressure applied. Interfacial contact resistance values were measured by measuring the voltage between the sample and the carbon paper.

In addition, in the examples and comparative examples, in order to confirm the corrosion resistance, the interfacial contact resistance value of the sample before being immersed in a 1 mol / L sodium hydroxide aqueous solution at 70 ° C. (hereinafter referred to as the interfacial contact resistance value or immersion Also referred to as the interfacial contact resistance value before), and the interfacial contact resistance value of the sample after being immersed in a 1 mol / L sodium hydroxide aqueous solution at 70 ° C. for 90 minutes (hereinafter also referred to as the interfacial contact resistance value after immersion. ) was measured. The immersed sample was washed with ultrapure water and dried in a vacuum constant temperature dryer at 23° C. for 120 minutes.

<Contact angle>
The contact angle was measured using a contact angle meter (BM-501 manufactured by Kyowa Interface Science Co., Ltd.). After removing dust from the surface of the sample before measuring the contact angle, the sample was placed in the sample holder of the contact angle meter. Next, the syringe was slowly pushed to drop a water droplet of 2.0 μL onto the surface of the sample. The contact angle was defined as the angle between the water droplet and the surface of the sample, and was read using analysis software FAMAS manufactured by Kyowa Interface Science Co., Ltd.

(Experimental result)
As shown in Table 1 and FIG. 7(b), Example p4 has a corrosion current density (Icorr (μA/cm ² )) of 0.973 μA/cm ² and only the first nickel layer on the stainless steel plate. was formed, comparative example p3 in which only the second nickel layer was formed on the stainless steel plate, and comparative example p1 in which only the stainless steel plate was not plated. It should be noted that the smaller the corrosion current density, the better the corrosion resistance.

Here, the graph of FIG. 7(a) shows the logarithmic value of the current changed by the oxidation-reduction reaction when the counter electrode, the reference electrode, and the working electrode are immersed in a 1 mol/L sodium hydroxide aqueous solution at 70° C. and the action. The relationship with the electrode potential is plotted using a high performance electrochemical measurement system. This plot is called a Tafel plot. The vertical axis is the logarithmic value of the current (Log(i/mA)), and the horizontal axis is the potential (V) of the working electrode. The corrosion potential is the potential (V) of the working electrode when the logarithmic value of the current is the smallest, that is, the potential when the oxidation rate and the reduction rate are equal. The SCE electrode was used as the reference electrode for comparing the potential (V) of the working electrode in FIG. 7(a). ), a silver/silver chloride electrode (Ag/AgCl electrode) was used as a reference electrode for comparison in the potential (V) of the working electrode of ).

The corrosion potential obtained in FIG. 7(a) is called Ecorr (mV vs. SCE) shown in FIG. 7(b), and the higher the value, the better the corrosion resistance. βa (mV) represents the anodic Tafel constant, and βc (mV) represents the cathode Tafel constant. βa (mV) and βc (mV) are obtained from the Tafel plot shown in FIG. It is a measured value and is used when calculating the corrosion current density (Icorr (μA/cm ² )). Rp (Ωcm ² ) represents the polarization resistance, which is the slope of the tangential line of the polarization curve in a very narrow range near the corrosion potential (Ecorr (mV vs. SCE)).

The meaning of the graphs and the explanation of the terms described above are the same for other drawings.

Further, as shown in Table 1 and FIG. 8, the contact angle of Example p4 was 101.7 degrees, which was found to be larger than those of Comparative Examples p1, p2, and p3.

In addition, as shown in Table 1 and FIG. 9, Example p4 had an interfacial contact resistance value of 0.75 mΩ ^cm before being immersed in a 1 mol/L sodium hydroxide aqueous solution at 70°C. The interfacial contact resistance value after immersion in a 1 mol/L sodium hydroxide aqueous solution was 3.7 mΩ·cm ² , which was found to be smaller than those of Comparative Examples p1, p2, and p3.

Furthermore, the stainless steel plate on which the first nickel layer is formed is immersed in the second nickel plating solution, and the nickel sulfate concentration and boric acid concentration of the second nickel plating solution and the current flowing through the stainless steel plate are kept constant. Differences in corrosion current density, interfacial contact resistance value, and contact angle of the polymer electrolyte fuel cell separator 40 were observed when the energization time was changed in this state. As shown in Table 2, FIG. 10(b) and FIG. 11, the corrosion current density (Icorr (μA/cm ² )) of Example p4 was about 1/5 of that of Comparative Example P24. Further, the interfacial contact resistance value (ICR (mΩ·cm ² )) of Example p4 in which the energization time is 1200 seconds is lower than that of Comparative Example p24 in which the energization time is 400 seconds and Comparative Example p25 in which the energization time is 800 seconds. It became about 1/3 or less compared.

Further, differences in corrosion current density, interfacial contact resistance value, and contact angle of the polymer electrolyte fuel cell separator 40 were observed when the temperature of the second nickel plating solution was changed. As shown in Table 2, FIG. 12(b) and FIG. 13, the corrosion current density (Icorr (μA/cm ² )) of Example p4 was about 1/4 that of Comparative Example p26. Further, the interfacial contact resistance value (ICR (mΩ·cm ² )) of Example p4 at a temperature of 60°C was about 1/3 or less of that of Comparative Example p26 at a temperature of 25°C.

Furthermore, in the second nickel plating step, the potential of the stainless steel plate (working electrode) with respect to the reference electrode was changed with the distance between the stainless steel plate and the nickel plate being 10 mm and the current flowing through the stainless steel plate being -0.35 A. Differences in corrosion current density, interfacial contact resistance value, and contact angle of the polymer electrolyte fuel cell separator 40 were observed. As shown in Table 2, FIG. 14(b) and FIG. 15, the corrosion current density (Icorr (μA/cm ² )) of Example p4 was about 3/5 of that of Comparative Example p28. The interfacial contact resistance value (ICR (mΩ·cm ² )) of Example p4 with a potential of -1.0V was about 1/4 or less of that of Comparative Example p28 with a potential of -0.5V.

Further, differences in corrosion current density, interfacial contact resistance value, and contact angle of polymer electrolyte fuel cell separator 40 were observed when the concentration of hydrochloric acid in the first nickel plating solution was varied. As shown in Table 2, FIGS. 16(b) and 17, the corrosion current density (Icorr (μA/cm ² )) of Example p4 was about 3/5 of that of Comparative Example p30. The interfacial contact resistance value (ICR (mΩ·cm ² )) of Example p4 with a hydrochloric acid concentration of 3.5 mol/L is about 1/3 or less compared to Comparative Example p30 with a hydrochloric acid concentration of 1.0 mol/L. became.

From the above, the polymer electrolyte fuel cell separator 40 according to the embodiment has a corrosion current density of 1.100 μA/cm ² or less in the presence of a strong alkali. It is possible to provide a highly corrosive separator for an anion-exchange polymer electrolyte fuel cell in which the periphery of the separator is strongly alkaline.

Further, the polymer electrolyte fuel cell separator 40 according to the embodiment has an interfacial contact resistance value of 1.00 mΩ·cm ² or less before being immersed in a container filled with a 1 mol/L sodium hydroxide aqueous solution at 70°C. , and the interfacial contact resistance value after being immersed in a container filled with a 1 mol/L sodium hydroxide aqueous solution at 70°C is 10.0 mΩ cm ² or less, so it is generated in the polymer electrolyte fuel cell. can be supplied to an external circuit without loss of electricity.

Furthermore, the polymer electrolyte fuel cell separator 40 according to the embodiment has a large contact angle even if water generated inside the polymer electrolyte fuel cell adheres to the surface of the polymer electrolyte fuel cell separator. , can be discharged efficiently.

Therefore, the polymer electrolyte fuel cell separator 40 according to the embodiment can provide a polymer electrolyte fuel cell separator having excellent corrosion resistance and a low interfacial contact resistance value.

As described above, according to the present invention, it is possible to provide a polymer electrolyte fuel cell separator having excellent corrosion resistance and a low interfacial contact resistance value, and a method for producing the same.

The present invention is capable of various embodiments and modifications without departing from the broader spirit and scope of the invention. Moreover, the embodiment described above is for explaining the present invention, and does not limit the scope of the present invention. That is, the scope of the present invention is indicated by the claims rather than the embodiments. Various modifications made within the scope of the claims and the meaning of the invention equivalent thereto are considered to be within the scope of the present invention.

10, 20, 30 plating equipment,
100 metal plate, 120 first nickel layer, 130 second nickel layer,
140 nickel plate,
150 plating bath part, 151 plating bath, 153 first nickel plating solution, 154 second nickel plating solution, 310 third nickel plating solution, 152 heater,
160 control and measurement unit, 161 measurement unit, 162 power supply unit, 163 control unit,
170 external power supply;
168 ammeter,
167, 320 thermometers,
40, 41, 42 polymer electrolyte fuel cell separator,
43 anode catalyst layer 44 cathode catalyst layer 45, 46 gas diffusion layer 431, 432, 433, 434 fuel,
50 anion exchange polymer electrolyte fuel cell,
400 anode electrode, 420 cathode electrode,
410 polymer electrolyte membrane, 430 external circuit, 440 directions.

Claims (8)

a first nickel plating step of immersing a metal plate in a first nickel plating solution containing hydrochloric acid and nickel chloride to apply nickel plating to form a first nickel layer on the metal plate;
The metal plate having the first nickel layer formed thereon is immersed in a second nickel plating solution containing nickel sulfate and boric acid for nickel plating, and the first nickel layer is coated with the first nickel layer. a second nickel plating step to form a second nickel layer thicker than the nickel layer;
A method for producing a polymer electrolyte fuel cell separator comprising: The first nickel plating solution has a hydrochloric acid concentration of 2.0 mol/L or more and 3.5 mol/L or less,
The nickel chloride concentration of the first nickel plating solution is 0.5 mol/L or more and 2.0 mol/L or less,
The second nickel plating solution has a nickel sulfate concentration of 0.5 mol/L or more and 2.0 mol/L or less,
The boric acid concentration of the second nickel plating solution is 0.10 mol/L or more and 1.50 mol/L or less.
2. The method for manufacturing the polymer electrolyte fuel cell separator according to claim 1. The temperature of the first nickel plating solution when the metal plate is immersed in the first nickel plating solution is 15° C. or higher and 50° C. or lower,
The temperature of the second nickel plating solution when the metal plate on which the first nickel layer is formed is immersed in the second nickel plating solution is 45 ° C. or higher and 65 ° C. or lower.
3. The method for manufacturing the polymer electrolyte fuel cell separator according to claim 1 or 2. The first nickel plating process is an electrolytic plating process, and the current density is 0.15 A/cm ² or more and 0.4 A/cm ² or less,
The second nickel plating process is an electrolytic plating process, and the current density is 0.15 A/cm ² or more and 0.4 A/cm ² or less.
4. A method for producing a polymer electrolyte fuel cell separator according to any one of claims 1 to 3. 5. The method for producing a polymer electrolyte fuel cell separator according to claim 1, wherein the metal plate is made of one selected from the group consisting of stainless steel, aluminum, magnesium, and titanium. . a metal plate;
a first nickel layer formed on the metal plate;
a second nickel layer formed on the first nickel layer;
The thickness of the first nickel layer is 0.01 μm or more and 1.0 μm or less,
The second nickel layer has a thickness of 2.0 μm or more,
Corrosion current density is 0.001 μA/cm ² or more and 1.100 μA/cm ² or less,
The interfacial contact resistance value is 0.01 mΩ cm ² or more and 1.00 mΩ cm ² or less,
Separator for polymer electrolyte fuel cells. 7. The polymer electrolyte fuel cell separator according to claim 6, wherein the interfacial contact resistance value after being immersed in a 1 mol/L sodium hydroxide aqueous solution at 70[deg.] C. is 10.0 m[Omega].cm ^<2> or less. 8. The polymer electrolyte fuel cell separator according to claim 6, wherein said metal plate is made of one selected from the group consisting of stainless steel, aluminum, magnesium and titanium.

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