KR20230127571A - Metal seperator for solid oxide fuel cell - Google Patents

Abstract

The present invention relates to a metal separator for a solid oxide fuel cell, which includes: a metal plate member having a passage through which fuel gas or air is supplied; and a Co-Ni-X plating layer formed on the surface of the metal plate member, wherein the Co-Ni-X plating layer is formed by an electroless plating method using a Co-Ni-X plating solution, and X is boron (B).

Description

Metal separator for solid oxide fuel cell}

The present invention relates to a metal separator of a solid oxide fuel cell, and in particular, by forming a Co(cobalt)-Ni(nickel)-X (reducing agent) plating layer on the surface of a metal plate-shaped member using an ionization reaction of an electroless plating method to form a metal Corrosion resistance is improved by preventing the formation of Cr ₂ O ₃ that can occur as STS 400 series (Fe-Cr series) is used for the plate-shaped member, and Ni It relates to a metal separator of a solid oxide fuel cell capable of improving electrical characteristics by reducing sheet resistance resistance by maximizing the content of Co while minimizing the content of.

Solid oxide fuel cells are manufactured in various shapes and with a flat-type solid oxide fuel cell (SOFC) stack. The flat SOFC stack is manufactured in a structure in which unit cells and metal separators are alternately stacked. In the unit cell, an oxygen ion conductive electrolyte, a cathode and an anode are disposed on both sides of the electrolyte. In the metal separator, a flow path for supplying fuel gas or air is formed in a concave or embossed shape. A technology related to a solid oxide fuel cell composed of a unit cell and a metal separator is disclosed in Korean Patent Publication No. 10-2009-0015121 (Patent Document 1).

Patent Document 1 relates to a plate solid oxide fuel cell, a plate-type single cell each composed of a plate-type solid electrolyte, and an anode and an air electrode disposed on both sides of the solid electrolyte are alternately arranged with metal separators, respectively. , The fuel supply chamber is formed between the anode and the side of the metal separator opposite the fuel electrode, and the air supply chamber is formed between the air electrode and the side of the metal separator opposite the air electrode.

The plate solid oxide fuel cell as in Patent Document 1 is a plate-type SOFC stack, the plate-type unit cell is a unit cell, and the metal separator represents a metal separator. A metal bipolar plate used in a conventional flat SOFC stack, that is, a solid oxide fuel cell, as in Patent Document 1 is formed in a plate shape in which a flow path for supplying fuel gas or air is engraved or embossed, and the flat SOFC stack Ferritic stainless steel is used to improve durability to secure long life while operating at a high temperature of 650 ~ 1000℃. Ferritic stainless steel has STS 400 series, and STS 400 series is made of Fe-Cr alloy.

The conventional solid oxide fuel cell described in Patent Document 1 has insulator properties in evaporation of chromium at high temperature according to the operation of the flat SOFC stack due to volatilization of Cr when Fe-Cr alloy is used as a metal separator. There is a problem in that Cr ₂ O ₃ is formed on the metal surface and deteriorates the electrical characteristics of the solid oxide fuel cell.

: Korean Patent Publication No. 10-2009-0015121

An object of the present invention is to solve the above-described problems, by using the ionization reaction of the electroless plating method to form a Co (cobalt) -Ni (nickel) -X (reducing agent) plating layer on the surface of the metal plate-like member to form a metal plate-like member Corrosion resistance is improved by preventing the formation of Cr ₂ O ₃ that can occur as the material of STS 400 (Fe-Cr) is used, and the amount of Ni is controlled by adjusting the amount of precipitation through X formed by the eutectoid reaction. It is to provide a metal separator of a solid oxide fuel cell capable of improving electrical characteristics by reducing sheet resistance resistance by maximizing the content of Co while suppressing to a minimum.

Another object of the present invention is to form a Co-Ni-X plating layer on the surface of the metal plate-shaped member to form a diffusion barrier, so that the material of the metal plate-shaped member is Cr ( It is an object of the present invention to provide a metal separator for a solid oxide fuel cell capable of improving reliability of a product by increasing thermal stability by suppressing an increase in resistance due to evaporation of chromium).

Another object of the present invention is to form a Co-Ni-X plating layer using an electroless plating method so that the flow path is formed in a concave or embossed manner so that it can be applied uniformly regardless of the shape or surface area of a metal plate-shaped member with many irregularities. It is to provide a metal separator of a solid oxide fuel cell that can improve the bonding strength when stacking metal separators by improving the density of the Co-Ni-X plating layer.

The metal separator of the solid oxide fuel cell of the present invention includes a metal plate-like member in which a flow path through which fuel gas or air is supplied is formed, and a Co-Ni-X plating layer formed on the surface of the metal plate-like member, and the Co- The Ni-X plating layer is formed by an electroless plating method using a Co-Ni-X plating solution, and the X is characterized in that B (boron).

The metal separator of the solid oxide fuel cell of the present invention uses the ionization reaction of the electroless plating method to form a Co-Ni-X plating layer on the surface of the metal plate member to make the material of the metal plate member STS 400 (Fe-Cr) ) is used to prevent the formation of Cr ₂ O ₃ that can occur, thereby improving corrosion resistance, and by controlling the amount of precipitation through X formed by eutectoid reaction, the content of Ni is minimized while the content of Co is maximized. It has the advantage of improving the electrical characteristics by lowering the sheet resistance resistance, and by forming a Co-Ni-X plating layer on the surface of the metal plate member to form a diffusion barrier, the material of the metal plate member is made of STS 400 series (Fe- By using Cr-based), it has the advantage of improving product reliability by increasing thermal stability by suppressing the increase in resistance due to evaporation of Cr (chromium) at high temperature, and by using the electroless plating method, Co-Ni- By forming the X plating layer, the flow path is molded in a negative or embossed shape, so that it can be applied uniformly regardless of the shape or surface area of a metal plate member with many irregularities, improving the density of the Co-Ni-X plating layer to stack the metal separators. There is an advantage that can improve bonding strength upon application.

1 is a plan view of a metal separator of a solid oxide fuel cell of the present invention;
2 is a cross-sectional view along line A1-A2 of the metal separator shown in FIG. 1;
3 is a table showing an SEM image of part A3 shown in FIG. 1;
Figure 4 is a flow chart showing a manufacturing process of the metal separator of the solid oxide fuel cell of the present invention.

Hereinafter, an embodiment of a metal separator of a solid oxide fuel cell according to the present invention will be described with reference to the accompanying drawings.

1 and 2, the metal separator 100 of the solid oxide fuel cell of the present invention includes a metal plate-like member 110, a Co (cobalt) -Ni (nickel) -X plating layer 120 and a metal strike layer ( 130).

In the metal plate-like member 110, a flow path 111 through which fuel gas or air is supplied is formed, a Co-Ni-X plating layer 120 is formed on the surface of the metal plate-shaped member 110, and a Co-Ni-X plating layer (120) is formed by an electroless plating method using a Co-Ni-X plating solution, and B (boron) is used for X.

A specific embodiment of the metal bipolar plate 100 of the solid oxide fuel cell of the present invention will be described.

As shown in FIG. 1, the metal plate member 110 has a flow path 111 formed to supply fuel gas or air to a solid oxide fuel cell (not shown), and the flow path 111 is embossed or embossed as shown in FIG. It is formed as an intaglio (not shown). The metal plate-shaped member 110 has a rectangular surface, is made of stainless steel, and uses STS 400 (Fe-Cr) stainless steel. The flow path 111 is formed between the protruding members 111a and the protruding members 111a by forming protruding members 111a spaced apart from each other and arranged on the surface of one side or the other side of the metal plate-shaped member 110 at regular intervals. That is, the metal plate-shaped member 110 is embossed so that a plurality of protruding members 111a are formed to be spaced apart from each other at regular intervals, and a flow path 111 is formed between the protruding members 111a and the protruding members 111a.

The metal plate member 110 is subjected to pretreatment before forming the metal strike layer 130 . The pretreatment of the metal plate-shaped member 110 is performed by alkali degreasing using an aqueous solution of sodium metasilicate (Na ₂ SiO ₃ ) at a concentration of 1 to 20%, and the metal plate-shaped member 110 subjected to alkali degreasing is 15 Acid etching is performed by immersion at ~35°C for 5 to 15 minutes, an aqueous hydrochloric acid solution is used as the acid solution, and the aqueous hydrochloric acid solution is formed by mixing 10 to 20% by volume of hydrochloric acid and 80 to 90% by volume of water. Here, the aqueous solution of sodium metasilicate (Na ₂ SiO ₃ ) at a concentration of 1 to 20% represents a state in which 1 to 20 g of sodium metasilicate (Na ₂ SiO ₃ ) is dissolved in 100 g of water.

The Co-Ni-X plating layer 120 is an electroless plating method using a Co-Ni-X plating solution on the metal plate-shaped member 110 having the metal strike layer 130 formed on the surface after pretreatment as shown in FIGS. 1 and 2 X is B (boron), and the content ratio of Co, Ni, and B is 88 to 93 wt% for Co, 4 to 10 wt% for Ni, and 2 to 3 wt% for B, so that the sheet resistance is 25 mΩ or less. Formed. The Co-Ni-X plating layer 120 is formed to have a thickness of 3 to 15 μm.

The Co-Ni-X plating solution is a plating solution for forming the Co-Ni-X plating layer 120 and contains 15 to 25 g/L of a cobalt compound, 2 to 5 g/L of a nickel compound, 30 to 50 g/L of an organic acid, and 5 to 50 g/L of a reducing agent. 10 g/L and a surfactant of 0.5 to 1 g/L, and the concentration of the reducing agent is adjusted to be 5 to 10 g/L in the Co-Ni-X plating solution so that Co, Ni of the Co-Ni-X plating layer 120 And the content ratio of Co 88 ~ 93wt%, Ni 4 ~ 10wt%, and B 2 ~ 3wt%, so that the sheet resistance of the Co—Ni—X plating layer 120 is 25 mΩ or less. In the Co-Ni-X plating solution, ammonium citrate is used as the organic acid and either dimethyl amino borane (DMBA) or morpholine borane (MB) is used as the reducing agent, and Co, The content ratio of Ni and B is 88 to 93 wt% of Co, 4 to 10 wt% of Ni, and 2 to 3 wt% of B. That is, the Co-Ni-X plating layer 120 is plated with a Co-Ni-X plating solution by an electroless plating method, and ammonium citrate is used as an organic acid included in the Co-Ni-X plating solution to form a reducing agent. Either DMBA or MB is used, and the content ratios of Co, Ni, and B are 88 to 93 wt% for Co, 4 to 10 wt% for Ni, and 2 to 3 wt% for B.

In the Co-Ni-X plating solution, cobalt sulfate is used as the cobalt compound, nickel sulfate is used as the nickel compound, and either dimethyl amino borane (DMBA) or morpholine borane (MB) is used as the reducing agent. Ammonium citrate is used as the organic acid, and one of benzalkonium chloride, chitosan, ammonium lauryl sulfate, methanol, ethanol, and acetate is used as the surfactant. The Co-Ni-X plating solution may include a metal salt, and the metal salt is selected from among phosphorus, bromine, bismuth, lead, gallium, indium, and thallium.

The Co-Ni-X plating layer 120 is formed as shown in FIG. 3 depending on whether the surfactant is included in the Co-Ni-X plating solution. FIG. 3 is a table showing a partially enlarged SEM (scanning electron microscope) picture of A3 of the Co-Ni-X plating layer 120 shown in FIG. 1 . In FIG. 3, the SEM picture (#1) shows that the Co-Ni-X plating layer 120 is formed in a state where no surfactant is included in the Co-Ni-X plating solution, and the Co-Ni-X plating layer 120 is uniform. On the other hand, the SEM picture (#2) shows that the Co-Ni-X plating layer 120 is formed in a state in which a surfactant is included in the Co-Ni-X plating solution, and the Co-Ni-X plating layer 120 is uniform. It can be seen that it has been formed. As such, the metal bipolar plate 100 of the present invention includes a surfactant in the Co-Ni-X plating solution as shown in FIG. was formed. That is, the SEM picture (#2) of FIG. 3 prevents the occurrence of pits, such as the part partially displayed in white in the SEM picture (#1), by including a surfactant in the Co-Ni-X plating solution. This shows a state in which the Co-Ni-X plating layer 120 is uniformly formed, and sheet resistance can be lowered due to the uniformly plated Co-Ni-X plating layer 120.

One embodiment of the metal strike layer 130 is formed between the metal plate-like member 110 and the Co-Ni-X plating layer 120, as shown in FIG. 2, and the metal strike layer 130 is a nickel strike layer (shown not) is used, and the nickel strike layer is formed by plating a nickel strike plating solution containing nickel chloride on the surface of the pretreated metal plate-like member 110.

In another embodiment of the metal strike layer 130, a nickel strike layer is formed on the surface of the pre-treated metal plate member 110, and then a cobalt strike layer (not shown) is formed on the surface of the nickel strike layer. The nickel strike layer is formed by plating a nickel strike plating solution containing nickel chloride on the surface of the pretreated metal plate-like member 110, and the cobalt strike layer is formed by plating a cobalt strike plating solution containing cobalt chloride on the surface of the nickel strike layer The thickness or plating time of the cobalt strike layer is smaller than the thickness or plating time of the nickel strike layer, respectively, so that the surface of the nickel strike layer is partially exposed after plating the cobalt strike layer. As such, the metal strike layer 130 forms a nickel strike layer to improve the adhesion with the surface of the metal plate-like member 110 when the Co-Ni-X plating layer 120 is formed, and the cobalt strike layer is partially formed on the nickel strike layer By plating with, the Ni content in the Co-Ni-X plating layer 120 is prevented from increasing due to the nickel strike layer.

In order to test the electrical characteristics of the metal bipolar plate 100 of the solid oxide fuel cell of the present invention, comparative examples and embodiments of the present invention were manufactured, respectively.

All of the metal separators 100 according to Comparative Examples 1 to 4 and Examples 1 to 4 used the same metal separators 100 having the flow path 111 formed thereon, and the metal separators 100 The material used was STS 400 system (Fe-Cr system). The STS 400-based (Fe-Cr-based) metal separator 100 was pretreated as shown in FIG. 4 . In the pretreatment of the metal bipolar plate 100 according to Comparative Examples 1 to 4 and Examples 1 to 4, as shown in FIG. 4, the electroless alkali degreasing step (S110) is performed and then the acid etching step is performed. (S120) was performed, and a nickel strite layer forming step (S130) was performed on the metal bipolar plate 100 after acid etching was completed.

In the electroless alkali degreasing step (S110), the metal separator 100 according to Comparative Examples 1 to 4 and Examples 1 to 4 is alkaline using an aqueous solution of sodium metasilicate (Na ₂ SiO ₃ ) at a concentration of 10%. Degreasing was carried out, a surfactant was added to improve the function of alkali degreasing, and the surfactant silver acetate was used.

The acid etching step (S120) was performed to improve adhesion by increasing the surface area of the metal bipolar plate 100 according to Comparative Examples 1 to 4 and Examples 1 to 4 in which electroless alkali degreasing was completed, and acid Acid etching was performed by immersing at 25° C. for 10 minutes using the solution, and an aqueous hydrochloric acid solution formed by mixing 15 vol% of hydrochloric acid and 85 vol% of water was used as the acid solution.

In the step of forming a nickel strike layer (S130), in one embodiment, a nickel strike layer is formed to a thickness of 05 to 0.1 μm by using a nickel strike plating solution containing nickel chloride on the surface of the acid-etched metal separator 100. form Another embodiment of the nickel strite layer forming step (S130) is to use a nickel strike plating solution containing nickel chloride on the surface of the metal plate-like member 110 after the pretreatment, that is, acid etching, to have a thickness of 0.5 to 0.1 μm. After forming the strike layer, a cobalt strike layer (not shown) is formed on the surface of the nickel strike layer to have a thickness of 00.5 to 1 μm using a cobalt strike plating solution containing cobalt chloride. Here, the cobalt strike layer is formed smaller than the thickness of the nickel strike layer. However, in the metal separators 100 according to Comparative Examples 1 to 4 and Examples 1 to 4 of the present invention, a nickel strike layer was formed to a thickness of 0.1 μm using a nickel strike plating solution.

In the method of forming the nickel strite layer 130 on the surface of the metal bipolar plate 100 according to Comparative Examples 1 to 4 and Examples 1 to 4, the material of the metal bipolar plate 100 is STS 400 series (Fe-Cr-based) is used, so it is plated at 2V (voltage) for 2 minutes using a plating solution containing 240g/L of nigel chloride (NiSO ₄ -6H ₂ O) to form a nickel strike layer to a thickness of 0.1㎛ As shown in FIG. 3, the surface of the metal bipolar plate 100 with low activity is formed with matte gray plating to improve post-plating, that is, the adhesion of the Co-Ni-X plating layer 120. The plating solution of the nickel strike layer is plated at 2V (voltage) for 2 minutes using a plating solution containing a mixture of nigel chloride (NiSO ₄ -6H ₂ O) and hydrochloric acid (HCl) to form a nickel strike layer with a thickness of 0.1 μm. A plating solution in which nigel chloride (NiSO ₄ -6H ₂ O) and hydrochloric acid (HCl) are mixed is formed by mixing 240 g/L of nigel chloride (NiSO ₄ -6H ₂ O) and 125 g/L of hydrochloric acid (HCl).

When the post-treatment of forming a nickel strike layer on each surface of the metal bipolar plate 100 according to Comparative Examples 1 to 4 and Examples 1 to 4 is completed under the same conditions, as shown in FIG. 4, Co- By performing the Ni-X plating layer forming step (S140), each Co-Ni-X plating layer 120 was formed to have a thickness of 10 μm.

As shown in Table 1, in the metal bipolar plate 100 according to Comparative Example 1, the Co-Ni-X plating layer 120 was formed by an electroless plating method using a Co-Ni-X plating solution.

As shown in Table 1, the metal separator 100 according to Comparative Example 1 includes 15 g/L of cobalt sulfate as a cobalt compound, 5 g/L of nickel sulfate as a nickel compound, and 5 g/L of nickel sulfate as an organic acid in the metal plate-like member 110 having a nickel strike layer formed thereon. Co-Ni-X plating layer using an electroless plating method using a Co-Ni-X plating solution containing 35 g/L of ammonium citrate, 15 g/L of sodium hypophosphite as a reducing agent, and 0.5 g/L of benzalkonium chloride as a surfactant. (120) was formed. As shown in Table 1, the metal separator 100 according to Comparative Example 2 contains 15 g/L of cobalt sulfate, 15 g/L of nickel sulfate, 50 g/L of ammonium citrate, hypophosphorous acid The Co-Ni-X plating layer 120 was formed using an electroless plating method using a Co-Ni-X plating solution containing 25 g/L of sodium and 1 g/L of benzalkonium chloride. As shown in Table 1, the metal separator 100 according to Comparative Example 3 contains 25 g/L of cobalt sulfate, 25 g/L of nickel sulfate, 35 g/L of ammonium citrate, and hypophosphorous acid in the metal plate member 110 having a nickel strike layer. The Co-Ni-X plating layer 120 was formed using an electroless plating method using a Co-Ni-X plating solution containing 20 g/L of sodium and 0.5 g/L of benzalkonium chloride. As shown in Table 1, the metal separator 100 according to Comparative Example 4 contains 25 g/L of cobalt sulfate, 5 g/L of nickel sulfate, 50 g/L of ammonium citrate, and hypophosphorous acid in the metal plate-like member 110 having a nickel strike layer. The Co-Ni-X plating layer 120 was formed using an electroless plating method using a Co-Ni-X plating solution containing 25 g/L of sodium and 1 g/L of benzalkonium chloride.

As shown in Table 2, the metal separator 100 according to Example 1 includes 15 g/L of cobalt sulfate as a cobalt compound, 2 g/L of nickel sulfate as a nickel compound, and 2 g/L of nickel sulfate as an organic acid in the metal plate-shaped member 110 on which the nickel strike layer is formed. Co-Ni-X plating layer (120 ) was formed. As shown in Table 2, the metal separator 100 according to Example 2 contains 15 g/L of cobalt sulfate, 2 g/L of nickel sulfate, 50 g/L of ammonium citrate, and 10 g of DMBA in the metal plate-like member 110 having a nickel strike layer. The Co-Ni-X plating layer 120 was formed using an electroless plating method using a Co-Ni-X plating solution containing /L and 1 g/L of benzalkonium chloride. As shown in Table 2, the metal separator 100 according to Example 3 contains 25 g/L of cobalt sulfate, 5 g/L of nickel sulfate, 35 g/L of ammonium citrate, and 5 g of DMBA in the metal plate-shaped member 110 on which the nickel strike layer is formed. The Co-Ni-X plating layer 120 was formed using an electroless plating method using a Co-Ni-X plating solution containing /L and 0.5 g/L of benzalkonium chloride. As shown in Table 2, the metal separator 100 according to Example 4 contains 25 g/L of cobalt sulfate, 5 g/L of nickel sulfate, 50 g/L of ammonium citrate, and 10 DMBA in the metal plate-like member 110 having a nickel strike layer. The Co-Ni-X plating layer 120 was formed using an electroless plating method using a Co-Ni-X plating solution containing g/L and 1 g/L of benzalkonium chloride.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4

plating solution
Furtherance Cobalt sulfate (g/L) 15 15 25 25 Nickel sulfate (g/L) 5 15 5 25 Ammonium citrate (g/L) 35 50 35 50 Sodium hypophosphite (g/L) 15 25 20 25 Surfactant (g/L) 0.5 One 0.5 One
evaluation
result
EDS analysis result
(wt%) Co

X
65 80 71 Ni 27 14 22 P 8 6 7 Sheet resistance (mΩ/cm2) 510 180 230

division Example 1 Example 3 Example 3 Example 4

plating solution
Furtherance Cobalt sulfate (g/L) 15 15 25 25 Nickel sulfate (g/L) 2 2 5 5 Ammonium citrate (g/L) 35 50 35 50 DMAB (g/L) 5 10 5 10 Surfactant (g/L) 0.5 One 0.5 One
evaluation
result
EDS analysis result
(wt%) Co 88 90 92 93 Ni 10 7.7 5.2 4 B 2 2.3 2.8 3 Sheet resistance (mΩ/cm2) 25 23 21 19

In the metal separators 100 according to Comparative Examples 1 to 4 and Examples 1 to 4, the same material of the metal plate member 110 was used as STS 400 (Fe-Cr), and the pretreatment Even the nickel strike layer was formed, but the metal separator 100 according to Comparative Examples 1 to 4 used ammonium citrate as an organic acid included in the Co-Ni-X plating solution and sodium hypophosphite as a reducing agent to form Co-Ni The thickness of the -X plating layer 120 was formed to be 10 μm.

As for the evaluation results of the metal bipolar plate 100 according to Comparative Example 1, as shown in Table 1, the evaluation results are indicated by 'X'. That is, the metal separator 100 according to Comparative Example 1 indicated by 'X' used ammonium citrate as an organic acid and sodium hypophosphite as a reducing agent, but contained a low concentration of sodium hypophosphite to form a Co-Ni-X plating layer. (120), the content ratio of Co and Ni, P (phosphorus) content and sheet resistance were not measured. As shown in Table 1, the evaluation results of the metal separators 100 according to Comparative Examples 2 to 4 show that ammonium citrate was used as an organic acid, but sodium hypophosphite was used as a reducing agent, so that the Co-Ni-X plating layer (120 ) is formed so that the content ratio of Co, Ni, and B is 65 to 80 wt% Co, 14 to 27 wt% Ni, and 6 to 8 wt% P, respectively, so that the content ratio of Ni exceeds 10%, so that the content ratio of Co It was formed lower than 88wt%, that is, it was not formed to the maximum, and as a result, the sheet resistance was measured as high as 510mΩ, 180mΩ, and 230mΩ, respectively.

As shown in Table 1, in the case of using sodium hypophosphite as a reducing agent in the Co-Ni-X plating solution, the metal bipolar plate 100 according to Comparative Examples 1 to 4 is set to a low concentration of sodium hypophosphite. The physical or electrical properties of the Co-Ni-X plating layer 120 cannot be measured, and when the concentration is set high, X becomes P (phosphorus) in the Co-Ni-X plating layer and the content of P is 5 to 8 wt. %, which increases the sheet resistance. For example, the metal separators 100 according to Comparative Examples 1 to 4 used ammonium citrate as an organic acid and sodium hypophosphite as a reducing agent, so that the concentrations of nickel sulfate and sodium hypophosphite should be set high to Co-Ni The -X plating layer 120 may be formed to have a thickness of 0 μm. That is, in the metal separator 100 according to Comparative Examples 1 to 4, 5 to 25 g of nickel sulfate is added to the Co-Ni-X plating solution to form the thickness of the Co-Ni-X plating layer 120 to be 10 μm. /L and 15 to 25 g/L of sodium hypophosphite are required, and since the concentration of nickel sulfate is high, the Ni content of the Co-Ni-X plating layer 120 cannot be minimized, so the Co content cannot be maximized, As a result, the sheet resistance was formed to exceed 25 mΩ.

As shown in Table 2, the metal separators 100 according to Examples 1 to 4 used ammonium citrate as an organic acid included in the Co-Ni-X plating solution and used DMBA as a reducing agent to form Co-Ni-X In order to form the thickness of the plating layer 120 to be 10 μm, 2 to 5 g/L of nickel sulfate and 5 to 10 g/L of DMBA are required, and in a state where the Ni content of the Co-Ni-X plating layer 120 is minimized The content of Co can be maximized so that the sheet resistance is less than 25 mΩ. That is, as shown in Table 2, the evaluation results of the metal bipolar plate 100 according to Example 1 show that X is B in the Co-Ni-X plating layer 120 by using ammonium citrate as an organic acid and using DMBA as a reducing agent. (boron), and the content ratio of Co, Ni, and B of the Co-Ni-X plating layer 120 is formed to be 88wt% Co, 10wt% Ni, and 2wt% B, respectively, so that the content ratio of Ni is 10%. The content ratio of Co was formed to be maximum, and the sheet resistance of the Co-Ni-X plating layer 120 was measured as low as 25 mΩ. As in Example 1, the evaluation results of the metal bipolar plate 100 according to Examples 2 to 4 are as shown in Table 2, by using DMBA as a reducing agent, X in the Co-Ni-X plating layer 120 is B (boron), and the content ratio of Co, Ni, and B of the Co-Ni-X plating layer 120 is formed so that Co 90 ~ 93wt%, Ni 4 ~ 7.7wt%, and B 2 ~ 3wt%, respectively, so that the content ratio of Ni Since all of these were formed at 10% or less, the content ratio of Co was formed to be maximum, and the sheet resistance of the Co-Ni-X plating layer 120 was measured as low as 19 to 23 mΩ, respectively.

As shown in Table 2, in the metal bipolar plate 100 according to Examples 1 to 4, citric acid is an organic acid included in the Co-Ni-X plating solution used to form the Co-Ni-X plating layer 120. By using ammonium, it was confirmed that plating was possible even if the nickel content was adjusted or the reducing agent was changed from sodium hypophosphite to DMBA. That is, the metal separator 100 according to Examples 1 to 4 uses ammonium citrate as an organic acid in the Co-Ni-X plating solution, so that the reducing agent is changed from sodium hypophosphite to DMBA, and the reducing agent uses DMBA. As a result, it is possible to plate so that the thickness of the Co-Ni-B plating layer (not shown) is 10 μm even when the nickel sulfate 2 ~ 5 g / L and DMBA 5 ~ 10 g / L are respectively set low in the Co-Ni-X plating solution. confirmed that As such, the metal bipolar plate 100 according to Examples 1 to 4 increases the thickness of the Co-Ni-X plating layer 120 in a state where the concentrations of nickel sulfate and DMBA are low in the Co-Ni-X plating solution. It can be formed to be 10 μm, and the content of Co can be maximized by minimizing the content of Ni in the Co-Ni-X plating layer 120, so that the sheet resistance is less than 25 mΩ.

As shown in the evaluation results of Table 2, the Co-Ni-X plating layer 120 of the metal bipolar plate 100 of the present invention uses DMBA as a reducing agent, and the content ratio of Co, Ni, and B is Co 88 to 93 wt%, Even when Ni 4 to 10wt% and B 2 to 3wt% are set low, the thickness of the Co—Ni—X plating layer 120 can be formed to be 10 μm so that the sheet resistance is 25 mΩ or less. Among the evaluation results of Tables 1 and 2, the content ratio (%) of Co and Ni and the analysis result (wt%) of EDS (Energy Dispersive X-ray Spectroscopy) were obtained using a known EDS (Energy Dispersive X-ray Spectroscopy) measuring device. The sheet resistance was measured using a processed four point probe device.

As described above, the metal separator of the solid oxide fuel cell of the present invention uses DMBA as a reducing agent in the Co-Ni-X plating solution and sets the concentration of DMBA low to reduce the B content in the Co-Ni-X plating layer. In the contained state, the value of the Co content can be increased, so that the sheet resistance can be lowered, the corrosion behavior is excellent, and the plating layer having a uniform content can be obtained. The Co-Ni-X layer formed through the plating method may have excellent characteristics such as corrosion resistance and wear resistance.

The metal separator of the solid oxide fuel cell of the present invention can be widely applied as a plating technology for surface treatment of fuel cells or precision machine parts.

100: metal separator
110: metal plate member
120: Co-Ni-X plating layer
130: metal strike layer

Claims (9)

A metal plate-shaped member in which a flow path through which fuel gas or air is supplied is formed;
It includes a Co (cobalt) -Ni (nickel) -X plating layer formed on the surface of the metal plate-like member,
The Co-Ni-X plating layer is formed by an electroless plating method using a Co-Ni-X plating solution, and the metal separator of the solid oxide fuel cell in which X is B (boron). According to claim 1,
A metal separator of a solid oxide fuel cell in which stainless is used as the material of the metal plate-like member, and the stainless steel is STS 400 (Fe-Cr). According to claim 1,
The metal plate-like member is subjected to a pretreatment, and the pretreatment is performed by alkali degreasing using an aqueous solution of sodium metasilicate (Na ₂ SiO ₃ ) at a concentration of 1 to 20%. Acid etching is performed by immersing at 15 to 35 ° C. for 5 to 15 minutes, the acid solution is an aqueous hydrochloric acid solution, and the aqueous hydrochloric acid solution is formed by mixing 10 to 20% by volume of hydrochloric acid and 80 to 90% by volume of water. The aqueous solution of sodium metasilicate (Na ₂ SiO ₃ ) having a concentration of 1 to 20% is a metal separator of a solid oxide fuel cell in which 1 to 20 g of sodium metasilicate (Na ₂ SiO ₃ ) is dissolved in 100 g of water. According to claim 1,
The Co-Ni-X plating layer is a metal of a solid oxide fuel cell formed such that the content ratio of Co, Ni, and B is 88 to 93 wt% for Co, 4 to 10 wt% for Ni, and 2 to 3 wt% for B so that the sheet resistance is 25 mΩ or less. separator plate. According to claim 1,
The Co-Ni-X plating solution includes 15 to 25 g/L of a cobalt compound, 2 to 5 g/L of a nickel compound, 30 to 50 g/L of an organic acid, 5 to 10 g/L of a reducing agent, and 0.5 to 1 g/L of a surfactant, ,
The concentration of the reducing agent is adjusted to be 5 to 10 g/L in the Co-Ni-X plating solution so that the content ratio of Co, Ni, and B in the Co-Ni-X plating layer is 88 to 93 wt% Co and 4 to 10 wt% Ni. A metal separator of a solid oxide fuel cell formed so that the sheet resistance of the Co-Ni-X plating layer is 25 mΩ or less when the % and B are 2 to 3 wt%. According to claim 5,
The organic acid uses ammonium citrate, and the reducing agent uses either dimethyl amino borane (DMBA) or morpholine borane (MB), so that the Co, Ni, and B content ratio of the Co-Ni-X plating layer is Co 88 ~ 93wt%, Ni 4 ~ 10wt% and B 2 ~ 3wt% of the metal separator of the solid oxide fuel cell. According to claim 5,
As the cobalt compound, cobalt sulfate is used,
Nickel sulfate is used as the nickel compound,
The reducing agent is used by selecting one of DMBA or MB,
As the organic acid, ammonium citrate is used,
The metal separator of the solid oxide fuel cell in which one of benzalkonium chloride, chitosan, ammonium lauryl sulfate, methanol, ethanol and acetate is used as the surfactant. According to claim 1,
A metal strike layer is formed between the metal plate member and the Co-Ni-X plating layer,
The metal strike layer uses a nickel strike layer, and the nickel strike layer is formed by plating a nickel strike plating solution containing nickel chloride on the surface of the pretreated metal plate-like member. Metal separator of a solid oxide fuel cell. According to claim 1,
The metal strike layer is formed by forming a nickel strike layer on the surface of the pretreated metal plate member and then forming a cobalt strike layer on the surface of the nickel strike layer, the nickel strike layer is nickel chloride on the surface of the pretreated metal plate member It is formed by plating a nickel strike plating solution containing, the cobalt strike layer is formed by plating a cobalt strike plating solution containing cobalt chloride on the surface of the nickel strike layer, and the thickness or plating time of the cobalt strike layer is A metal separator of a solid oxide fuel cell that performs less than the thickness of the strike layer or the plating time.

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