JP5267774B2 - Fuel cell separator - Google Patents

Description

  The present invention relates to a fuel cell separator used for separating the flow areas of fuel gas and oxidant gas supplied to a single cell in a fuel cell unit.

Conventionally, as a separator for a fuel cell, it is made of a lanthanum chromite ceramic material and has a fuel electrode side compared to a unit cell in which a fuel electrode is provided on one side of a solid electrolyte plate and an air electrode is provided on the other side. There was one provided with a heat-resistant and good conductive material layer on the surface (see Patent Document 1).
Japanese Patent Laid-Open No. 9-190829

  By the way, in the solid electrolyte fuel cell, since the exothermic reaction due to the electrochemical reaction depends on the gas composition and the flowing direction, the temperature distribution is likely to be uneven. For this reason, in a conventional separator using a ceramic material such as lanthanum chromite, the thermal conductivity is very low, so when the fuel cell is started rapidly, it is caused by thermal stress caused by non-uniform temperature distribution. There is a risk of deformation, resulting in an increase in electrical resistance and a decrease in output, or damage to a joint with a single cell (unit cell).

  The present invention has been made in view of the above-described conventional situation. By making the separator highly thermally conductive, the fuel cell can be made uniform in temperature distribution during steady operation or rapid start-up of the fuel cell. It aims to provide a separator.

The separator for a fuel cell of the present invention is a separator of a fuel cell unit including a single cell and a plate-like separator that forms a gas flow path between the single cells. The separator includes a filling member made of a material having higher thermal conductivity than the Cr-containing Fe alloy, a material having higher corrosion resistance / oxidation resistance than the Cr-containing Fe alloy, and a higher corrosion resistance / oxidation resistance than the filling member. The packaging member made of any one of the materials having the property is provided, and the filling member is hermetically packaged by the packaging member, and the above configuration is a means for solving the conventional problems.

The fuel cell separator according to the present invention adopts the above-described configuration, so that it has both high thermal conductivity and sufficient corrosion resistance and oxidation resistance. At this time, the temperature distribution can be made uniform quickly, and deformation due to thermal stress, deterioration in performance, and the like can be prevented. In particular, since the filling member is hermetically packaged by the packaging member, it is possible to prevent a situation in which air or water vapor enters the inside of the packaging member and the filling member is oxidized.

  FIG. 1 is a diagram illustrating an example of a fuel cell unit. The illustrated fuel cell unit U includes a disk-shaped separator 3 that forms a gas flow path for fuel gas between a disk-shaped cell plate 2 that holds a single cell 1 and a cell plate 2 that includes the single cell 1. ing. The single cell 1 is a power generation element in which a solid electrolyte layer is sandwiched between a fuel electrode layer and an air electrode layer, and the illustrated example has an annular shape.

  Further, between the cell plate 2 and the separator 3, an inner ring 4 that forms a gas supply path and a discharge path in the center, and an outer ring 5 that seals between the outer periphery of the cell plate 2 and the separator 3. A fuel electrode side current collector 6 made of a material having elasticity and a flow path component 7 for allowing the fuel gas to flow through the entire fuel electrode of the single cell 1 are accommodated. Furthermore, on the outer side (upper side in FIG. 1) of the separator 3, an air electrode-side flow path component 8, an air electrode-side current collector 9, and another inner ring 4 are provided.

  The fuel cell unit U includes a cell plate 2 holding a single cell 1, a separator 3, inner rings 4 and 4, an outer ring 5, a fuel electrode side current collector 6, flow path components 7 and 8, and an air electrode side current collector. The fuel cell stack is configured by stacking a plurality of sheets. The fuel cell stack is accommodated in a case (not shown). And while supplying fuel gas between the cell board 2 and the separator 3 from the gas supply path which continues in the center, the air which is oxidant gas is supplied in a case, and electric power generation by an electrochemical reaction in the single cell 1 is carried out. Do.

  The solid electrolyte fuel cell having the above-described configuration is mounted on a vehicle as a power source for an electric vehicle. In such a case, the fuel cell must be able to cope with rapid start-up and increase / decrease in output according to the operating conditions.

  Hereinafter, embodiments of the fuel cell separator of the present invention used in the fuel cell unit U will be described.

  The separator S1 shown in FIG. 2 includes a thin plate-like filling member 11 having high thermal conductivity and a packaging member 12 having high corrosion resistance and oxidation resistance, and the filling member 11 is packaged by the packaging member 12. . Here, the filling member 11 is made of a material having higher thermal conductivity than the Cr-containing Fe alloy. On the other hand, the packaging member 12 is made of any one of a material having higher corrosion resistance and oxidation resistance than the Cr-containing Fe alloy and a material having higher corrosion resistance and oxidation resistance than the filling member 11.

  The packaging member 12 is made of, for example, two thin plates 12a and 12a made of SUS430 and having a thickness of about 50 μm. In the separator S1 shown in FIG. 2B, the outer peripheral ends of the thin plates 12a and 12a are bent by about 90 degrees toward each other, and the other thin plate 12a is placed inside one thin plate 12a with the filling member 11 therebetween. The filling member 11 is packaged with the packaging member 12 by fitting. Further, the separator S1 shown in FIG. 2C is obtained by packaging the filling member 11 with the packaging member 12 with the filling member 11 in between and the outer peripheral ends of the thin plates 12a and 12a folded into each other. .

  The separator S1 shown in FIG. 2 (d) has the filling member 11 interposed therebetween, and the outer peripheral ends of the thin plates 12a and 12a are joined to each other, and the joined portions are laser-welded. It is airtightly packaged. Further, the separator S1 shown in FIG. 2 (e) is formed by bending the outer peripheral ends of the two thin plates 12a and 12a toward each other by about 90 degrees, with the filling member 11 therebetween, and the other thin plate inside the one thin plate 12a. The filling member 11 is hermetically packaged with the packaging member 12 by fitting the fitting portions 12a and bonding the fitting portions. In addition, for example, a Ba—Ca—Si glass adhesive having a thermal expansion coefficient equivalent to that of SUS430, which is a material of the packaging member 12, can be used as the adhesive.

  Here, the filling member 11 requiring high thermal conductivity includes Cu, Cu alloy, Al, Al alloy, Ni alloy, Zn alloy, Cr, Au, Ag, Mo, Mo alloy, W, W alloy, AlSi, AlSiC, diamond, Al diamond, Cu diamond, Ag diamond, or the like can be used.

  In addition, the packaging member 12 requiring high corrosion resistance and high oxidation resistance is ensured of conductivity by forming Cr oxide on the alloy surface or in the vicinity of the alloy surface at a high temperature, and also has corrosion resistance and oxidation resistance. It is possible to use an Fe alloy containing 13% or more of Cr, which is excellent in the above.

  Further, when the unit cell 1 uses a yttria-based solid oxide electrolyte, the packaging member 12 has a coefficient of thermal expansion of about 11E-6 [1 / K]. SUS430, which is a ferritic stainless steel containing 15% or more Cr, ZMG232 (Hitachi Metals) containing 20% or more Cr, and Crofer22APU (Thyssen Krupp VDM), which is an iron-based chromium alloy. Etc. can be used.

  Furthermore, ceramics such as alumina and zirconia, and noble metals such as Pt, Au, and Ag can be used for the packaging member 12 as a material having higher corrosion resistance and oxidation resistance than the filling member 11.

  The separator S1 having the above configuration has a high thermal conductivity in the plane direction (the direction along the plane), mitigating uneven temperature distribution due to heat generation distribution generated during power generation, and deformation due to thermal stress. The fuel electrode side current collector 6 can be uniformly pressed against the single cell 1. Thereby, good electrical conductivity is always ensured, and it can contribute to high efficiency of the fuel cell.

  Further, the separator S1 is heated with rapid heating of the fuel cell at the time of rapid start-up of the fuel cell. At this time, it is difficult to uniformly heat the separator S1, but it has a high thermal conductivity. Therefore, even if it is non-uniform heating, a temperature distribution can be made uniform quickly and the thermal stress which generate | occur | produces in the single cell 1 and the cell board 2 can be relieved.

  Furthermore, in general, there is no material other than noble metals that has high corrosion resistance and oxidation resistance and high thermal conductivity. On the other hand, the separator S1 separates the functions of corrosion resistance, oxidation resistance and high thermal conductivity, gives the packaging member 12 high corrosion resistance and high oxidation resistance, and makes the filling member 11 have high thermal conductivity. Since it has a high thermal conductivity, relatively inexpensive Cu, Al, etc. can be used as the filling member 11, which can contribute to a reduction in manufacturing cost.

  Further, when the filling member 11 is hermetically packaged with the packaging member 12 as in the separator S1 shown in FIGS. 2D and 2E, seam welding, laser welding, diffusion bonding, and the like are adopted as the joining means. can do. Furthermore, a glass adhesive containing Ba, Ca, Si, or the like as a component, a brazing material containing Ni, Ag, Cu-containing Ag, or the like as a component can be used as the adhesive.

  As described above, the separator S1 in which the filling member 11 is hermetically packaged by the packaging member 12 can prevent a situation in which air or water vapor enters the inside of the packaging member 12 and the filling member 11 is oxidized. .

  Furthermore, the separator for fuel cells of this invention can be set as the structure which contact | adhered the packaging member 12 and the filling member 11 as more preferable embodiment.

  Here, in the case of sealing the filling member 11 with the packaging member 12 in addition to welding such as laser welding and spot welding, brazing of Ni, Ti, Ag, Cu containing Ag, or the like, A technique for reducing the pressure can be employed.

  The separator S1 in which the packaging member 12 and the filling member 11 are in close contact as described above can greatly reduce the contact thermal resistance and electrical contact resistance between the members 11 and 12, and the strength of the separator S1 itself. Can also be improved.

  Furthermore, as a more preferred embodiment, the fuel cell separator of the present invention can have a configuration in which the relative difference between the thermal expansion coefficient of the packaging member 12 and the thermal expansion coefficient of the filling member 11 is approximately 10% or less.

  As an example, when the material of the packaging member 12 is Crofer 22APU, the coefficient of thermal expansion is 10. Since E-6 [1 / K], the thermal expansion coefficient of the filling member 11 is 10. 30% Cu-containing Mo alloy that becomes E-6 [1 / K], and a coefficient of thermal expansion of 9 to 10. An E-6 [1 / K] 50% Cr-containing Cu alloy (JFE Precision, JFE Steel: JP-A-2005-330583) or the like can be used. However, the material of both members 11 and 12 is not limited to these.

  The separator S1 has a relative difference between the thermal expansion coefficient of the packaging member 12 and the thermal expansion coefficient of the filling member 11 of approximately 10% or less, so that both members are empirically even during high temperature operation of the fuel cell. It is possible to suppress the deformation of the separator S <b> 1 by suppressing the thermal stress generated between 11 and 12.

  Furthermore, the fuel cell separator according to the present invention has, as a more preferable embodiment, a structure in which the packaging member has a variable structure for maintaining the tight contact state between the packaging member and the filling member following the thermal deformation of the filling member. Can be.

  The separator S2 shown in FIG. 3 (a) has a disk shape similar to that shown in FIG. 2 and includes a filling member 11 and a packaging member 12. The packaging member 12 includes two thin plates 12a and 12a having a thickness of about 30 μm to 500 μm and a ring-shaped outer peripheral member 12b that seals between the outer peripheral portions. Moreover, the packaging member 12 has the clearance gap 13 between the outer peripheral member 12b and the filling member 11, and both sides of this clearance gap 13 are the flexible parts 12c and 12c as a variable structure.

  More specifically, Cu—Mo is used as the material for the filling member 11 and Crofer 22APU is used as the material for the packaging member, and the outer peripheral portion of the packaging member 12 is joined by laser welding.

  In the separator S2, when the filling member 11 is thermally expanded in the thickness direction and the planar direction (the direction along the plane), as shown in FIG. The gap 13 follows the thermal deformation of the filling member 11. Further, when the filling member 11 contracts in the thickness direction and the planar direction (direction along the plane), the packaging member 12 is made of the filling member 11 by the flexible portion 12c as shown in FIG. Follow deformation

  The separator S2 shown in FIG. 3D includes a filling member 11 and a packaging member 12 composed of two thin plates 12a and 12a having a thickness of about 30 μm to 500 μm, and the thin plates 12a and 12a are interposed between the filling members 11. Are joined by seam welding. In this case, the packaging member 12 has, as a variable structure, slanted side flexible portions 12c and 12c extending from the flat portion to the joint portion.

  When the filling member 11 is thermally expanded in the thickness direction and the planar direction (the direction along the plane), the packaging member 12 includes the flexible portion 12c and the separator S2, as shown in FIG. The gap 13 follows the thermal deformation of the filling member 11. In addition, when the filling member 11 contracts in the thickness direction and the planar direction (direction along the plane), the packaging member 12 is made of the filling member 11 by the flexible portion 12c as shown in FIG. Follow deformation

  A separator S2 shown in FIG. 3G includes a filling member 11 and a packaging member 12 composed of two thin plates 12a and 12a having a thickness of about 30 μm to 500 μm. The packaging member 12 includes two thin plates 12a and 12a and a ring-shaped outer peripheral member 12b that seals between the outer peripheral portions of each other. In addition, the packaging member 12 has a gap 13 between the outer peripheral member 12b and the filling member 11, and on both sides of the gap 13, a flexible portion 12c having a shape bent toward each other as a variable structure, 12c.

  For example, the packaging member 12 of the separator S2 is formed by press-molding the flexible portion 12c and joining the thin plates 12a and 12 and the outer peripheral member 12b with a Cu-Ag brazing material.

  When the filling member 11 is thermally expanded in the thickness direction and the planar direction (direction along the plane), the packaging member 12 includes the flexible portion 12c and the separator S2, as shown in FIG. The gap 13 follows the thermal deformation of the filling member 11. Further, when the filling member 11 contracts in the thickness direction and the planar direction (direction along the plane), the packaging member 12 is formed by the flexible portion 12c of the filling member 11 as shown in FIG. Follow deformation

  Since each of the separators S2 includes the flexible member 12c as a variable structure in the packaging member 12, even when the filling member 11 is thermally deformed, the filling member 11 and the packaging member follow the same. 12 can be maintained, and a conduction heat transfer path between the members 11 and 12 can always be secured.

  Further, by providing the variable structure in the packaging member 12 as described above, in the fuel cell that operates at a high temperature of, for example, 450 ° C. or more, the difference in displacement between the members 11 and 12 due to different coefficients of thermal expansion, particularly the displacement difference in the longitudinal direction. Even when becomes larger, the end portion of the packaging material 12 is deformed, so that thermal stress accompanying thermal expansion can be suppressed.

  Furthermore, since the cell plate 2 is formed of ceramics, cermet that is a mixture of ceramics and metal, etc., the thickness varies slightly. However, in the fuel cell stack in which the fuel cell units U including the separator S2 are stacked, even if the thickness of the cell plate 2 varies, the end of the separator S2 in each fuel cell unit U is deformed by the variable structure. The fuel cell unit U can be easily stacked without changing the stacking order or stacking interval according to the thickness of the cell plate 2.

  Further, the fuel cell separator according to the present invention is a fuel cell unit U in which a fuel electrode side current collector 6 having elasticity is accommodated between the cell plate 2 and the separator 3 as shown in FIG. On the other hand, the region of the filling member 11 can overlap with at least a part of the region of the fuel electrode side current collector 6 in the thickness direction of the separator.

  The separator S <b> 3 shown in FIG. 4A has a disk shape as in the previous embodiment, and includes an annular filling member 11 and a packaging member 12. The fuel electrode side current collector 6 interposed between the separator S3 and the cell plate 2 also has an annular shape. In the illustrated separator S3, the region of the filling member 11 and the region of the fuel electrode side current collector 6 are almost entirely overlapped.

  The separator S3 shown in FIG. 4B has a disc shape, and the filling member 11 is divided into four in the circumferential direction. The fuel electrode side filling member 6 has an annular shape. Thus, the illustrated separator S3 is in a state where the region of the filling member 11 partially overlaps the fuel electrode side current collector 6.

  The separator S3 constitutes the fuel cell unit U. When the plurality of fuel cell units U are stacked, the separator S3 is formed between the filling member 11 and the packaging member 12 by the reaction force of the fuel electrode side current collector 6 having elasticity. A load is generated between them, and the contact thermal resistance generated between the members 11 and 12 can be reduced. It was confirmed that the effect of reducing contact thermal resistance could not be obtained with a separator in which the region of the filling member and the region of the current collector did not overlap at all.

  4 (a) and 4 (b) show the embodiment of the fuel electrode side current collector 6, but the same effect can be obtained by providing the air electrode side current collector 9 with elasticity. . Furthermore, both the fuel electrode side current collector 6 and the air electrode side current collector 9 are provided with elasticity, so that the filling member 11 and the packaging are provided by the reaction force of the current collectors 6 and 9 on both sides of the separator S3. Loads are generated on both the air electrode side and the fuel electrode side of the member 12, and the contact thermal resistance can be further reduced.

  Furthermore, the separator for fuel cells of the present invention can be configured such that the thermal expansion coefficient of the filling member 11 is larger than the thermal expansion coefficient of the packaging member 12 as a more preferred embodiment.

  The separator S4 shown in FIGS. 5 (a) to 5 (d) has the same structure as the separator S2 shown in FIGS. 3 (d) to (i) and is filled with a packaging member 12 having a variable structure. As the material of the member 11, Cu having a higher thermal expansion coefficient than that of Crofer 22APU which is the material of the packaging member 12 is used.

  When SUS430, which is an 18% Cr-containing Fe alloy, is used as the material of the packaging member 12, the material of the filling member 11 includes Cu, Cu alloy, Al, Al alloy, Ni alloy, Zn alloy, Au and Ag or the like can be used.

  Said separator S4 makes the thermal expansion coefficient of the filling member 11 larger than the thermal expansion coefficient of the packaging member 12, so that the packaging member 11, the filling member 12, The contact thermal resistance between the members 11 and 12 can be reduced.

  Further, as a more preferred embodiment, the fuel cell separator of the present invention has a disk shape having a central hole, and the packaging member 12 is made of a material having a higher thermal expansion coefficient than that of the main body at the outer peripheral end thereof. It can be set as the structure provided with the outer peripheral member 12b. Further, as a further preferred embodiment, the fuel cell separator has a disk shape having a central hole, and the packaging member 12 has an inner circumference made of a material having a lower thermal expansion coefficient than the main body at the inner circumference end. It can be set as the structure provided with the member 12d.

  The fuel cell separator S5 shown in FIG. 6 has a disk shape having a central hole H, and includes an annular filling member 11 and the filling member 11 is packaged by a packaging member 12. The packaging member 12 includes two thin plates 12a and 12a, and an outer peripheral member 12b is interposed between the outer peripheral portions of the two thin plates 12a and 12a, and an inner peripheral member 12d is provided between the inner peripheral portions of the two thin plates 12a and 12a. Is intervening.

  Further, in the separator S2 shown in FIG. 3 (g), a flexible portion 12c having a bent shape is provided only on the outer peripheral portion of the packaging member 12 as a variable structure. On the other hand, the separator S5 of this embodiment includes flexible portions 12c and 12c as variable structures on the outer peripheral side and the inner peripheral side of the packaging member 12. Therefore, FIG. 3 (g) and FIG. 6 (b) show the same cross-sectional shape, but both have different cutting positions.

  More specifically, the material of the filling member 11 of this embodiment is Cu, Cu alloy, Al, Al alloy, Ni alloy, Zn alloy, Au, Ag, etc., as in the previous embodiment. The material of the 12 thin plates 12a is Crofer 22APU, ZMG232, or the like.

  For example, SUS316L is used as the material of the outer peripheral member 12b. In addition, when Crofer 22APU is used for the thin plate 12a, Ni-containing Fe alloys such as austenitic stainless steel and inconel can be used. Further, alumina is used as the material of the inner peripheral member 12d. In particular, when ZMG232 is used for the thin plate 12a, silica or the like can be used in addition to alumina.

  In the separator S5, the packaging member 12 includes the outer peripheral member 12b made of a material having a higher thermal expansion coefficient than that of the main body, and the outer peripheral member 12b is continuous over the entire circumference. The outer peripheral portion of the packaging member 12 greatly expands. Thereby, the main-body part of the packaging member 12 will be in the state pulled outside, the packaging member 12 is pressed against the filling member 11, and the contact thermal resistance between both the members 11 and 12 can be reduced.

  Further, in the separator S5 described above, the packaging member 12 includes an inner peripheral member 12d made of a material having a lower coefficient of thermal expansion than the main body, and the inner peripheral member 12d is continuous over the entire circumference. Since the inner peripheral portion of the packaging member 12 does not thermally expand during the operation, the main body of the packaging member 12 is pulled inward. Thereby, the packaging member 12 is pressed against the filling member 11, and the contact thermal resistance between the members 11 and 12 can be reduced.

  Therefore, if the packaging member 12 having both the outer peripheral member 12b and the inner peripheral member 12d is provided as in the separator S5 shown in FIG. 6, the pressing action of the packaging member 12 generated when thermally deformed is further increased. Thus, the contact thermal resistance between the filling member 11 and the packaging member 12 is further reduced.

  Furthermore, the fuel cell separator of the present invention may be configured such that the thermal expansion coefficients of the filling member 11 and the packaging member 12 are matched as a more preferred embodiment.

  The fuel cell separator S6 shown in FIG. 7 has the same configuration as that shown in FIG. The separator S6 uses SUS430 having a thermal expansion coefficient of 10E-6 [1 / K] as the material of the packaging member 12, and has the same thermal expansion coefficient as the material of the filling member 11 and the thermal conductivity. Is 200 [W / K] Cr—Cu composite material, and the filling member 11 and the packaging member 12 are spot-welded with a dot pattern (not shown).

  In the separator S6, since the thermal expansion coefficients of the filling member 11 and the packaging member 12 are equal, both the members 11 and 12 can be easily joined by means such as welding or brazing. In addition to reducing the contact thermal resistance, the mechanical strength of the separator itself can be increased.

  Furthermore, the fuel cell separator of the present invention has a configuration in which a flow path component (see FIG. 1) for forming a gas flow path between the cell plate 2 and the cell plate 2 is integrally provided as a more preferred embodiment. Can do.

  The separator S7 shown in FIGS. 8A and 8B is integrally provided with an anode side flow path component 7 for forming a fuel gas flow path between the separator S7. The flow path component 7 includes a packaging component 7 a made of the same material as the packaging member 12 and a filling component 7 b made of the same material as the filling member 11. Therefore, the filling component 7b has higher thermal conductivity than the packaging component 7a.

  Further, the separator S7 shown in FIGS. 8 (c) and 8 (d) is integrally provided with a cathode side flow path component 8 for forming a gas flow path of an oxidizing gas (air). The flow path component 8 is made of the same material as the packaging member 12 and integrated with the packaging member 12, and the filling component 8 b made of the same material as the filling member 11 and integrated with the filling member 11. Has

  Further, the separator S7 shown in FIG. 8 (e) integrally includes both the anode-side channel component 7 and the cathode-side channel component 8 described above.

  The separator S7 can improve the mechanical strength of the separator itself by integrating at least one of the flow path component 7 for flowing the fuel gas and the flow path component 8 for flowing the oxidant gas. By providing the filling parts 7b and 8b having high thermal conductivity also in the road part, the cross-sectional area that promotes thermal conduction is increased, and higher thermal conductivity can be achieved.

  Furthermore, as a more preferred embodiment, the fuel cell separator according to the present invention integrates the flow path parts 7 and 8 as described above, and then fills the parts 7b and 8b for filling more than the thermal expansion coefficients of the packaging parts 7a and 8a. It can be configured such that the thermal expansion coefficient of 8b is larger.

  The separator S8 shown in FIG. 9 is integrally provided with the anode-side flow path member 7, and the flow path member 7 is a separate packaging component 7a from the packaging member 12, and the filling member 11 is a separate filling. A component 7b is provided. At this time, ZMG232 is used as the material of the packaging part 7a, whereas Au having a higher thermal expansion coefficient than that of ZMG232 is used as the material of the filling part 7b.

  The separator S8 can obtain the same effect as the separator S7 of the embodiment shown in FIG. 8, and has a higher thermal expansion coefficient of the filling part 7b than the thermal expansion coefficient of the filling and packaging part 7a. By doing so, the contact thermal resistance between the two forming portions 7a and 7b in the flow path component 7 can also be reduced during operation of the fuel cell.

  Moreover, as shown in the enlarged view in FIG. 9, the adhesiveness to the cell plate 2 is improved by the thermal expansion of the filling component 8 b in the portion where the flow path component 7 and the cell plate 2 are in contact with each other. This not only reduces the contact thermal resistance between the cell plate 2 and the flow path component 7 but also prevents gas detouring by filling a slight gap between the cell plate 2 and the flow path component 7. And electrical contact resistance can be reduced.

  Furthermore, as a more preferred embodiment, the separator for a fuel cell of the present invention can be configured to include a welding prevention layer that prevents welding of both of the filling member 11 and the packaging member 12.

  Here, the separators S1 and S2 shown in FIGS. 2 and 3 bring the filling member 11 and the packaging member 12 into close contact with each other, thereby reducing the contact thermal resistance and the electrical contact resistance between the members 11 and 12. I have to. However, depending on the material of the filling member 11 and the packaging member 12, the filling member 11, which is a particularly high heat conductive material, may be dissolved and welded to the packaging member 12 due to high heat during operation of the fuel cell. If the thermal expansion coefficients of 11 and 12 are greatly different, the entire separator may be deformed due to thermal deformation of one member.

  Accordingly, the separator S9 shown in FIG. 10 is provided with a welding prevention layer 14 between the members 11 and 12 according to the material of the filling member 11 and the packaging member 12 to prevent the welding of both. More specifically, the material of the filling member 11 is Au, and the material of the packaging member 12 is SUS316L. The surface of the filling member 11 is spray coated with boron nitride (BN), and this is coated with the anti-welding layer 14. did.

  In addition, when the filling member 11 is a material having a relatively low melting point such as Cu, Al, Ag, and Au, Ag paste that is an anti-seize agent, BN, TiN that is a high heat resistant coating, CrN, or the like Is referred to as a welding prevention layer 14.

  Even if the surface of the filling member 11 is unraveled at a high temperature during the operation of the fuel cell by providing the welding prevention layer 14 between the filling member 11 and the packaging member 12 in the separator S9, both the members 11 and 12 are used. It is possible to prevent the separator from deforming due to welding or welding.

  Furthermore, the fuel cell separator of the present invention can be configured such that a film having a smaller hydrogen diffusion coefficient than the packaging member 12 is formed on the outer surface of the packaging member 12 as a more preferred embodiment.

  A separator S10 shown in FIG. 11 includes a packing member 11 made of Cu, a packaging member 12 made of SUS430 thin plates 12a, 12a and an outer peripheral member 12b having a thickness of 100 μm, and before constituting the fuel cell unit U, an electric furnace And a film (for example, an oxide film) 15 having a hydrogen diffusion coefficient smaller than that of the packaging member 12 is formed on the surface of the packaging member 12.

  The separator S10 is a material in which the filling member 11 causes hydrogen embrittlement such as Cu, and when the thickness of the thin plate 12a of the packaging member 12 including the Cr-containing Fe alloy is 200 μm or less, The wrapping member 12 may diffuse. Therefore, by forming the coating film 5 on the surface of the packaging member 12, the diffusion coefficient of hydrogen diffusing in the thickness direction of the packaging member 12 is reduced, and the amount of hydrogen permeating into the packaging member 12 is reduced. Accordingly, hydrogen embrittlement of the filling member 11 made of Cu or the like can be suppressed.

The separators S1 to S10 described in the above embodiments constitute a fuel cell unit U as shown in FIG. 1, and the fuel cell unit U is laminated to constitute a solid oxide fuel cell. In this case, the fuel cell is a solid oxide fuel cell that operates at a high temperature. Materials used for the solid oxide fuel cell include, but are not limited to, zirconia-based electrolytes, ceria-based electrolytes, and lanthanum garade-based electrolytes.

  The fuel cell equipped with the fuel cell separator of the present invention operates at a high temperature of, for example, 450 ° C. or more, and the separator has corrosion resistance and oxidation resistance and is highly thermally conductive. As a result, the temperature distribution in the separator becomes uniform quickly, preventing deformation due to thermal stress, and at the same time, contact thermal resistance and electrical contact resistance can be greatly reduced, and good power generation performance can be maintained. .

  The detailed configuration of the separator for a fuel cell of the present invention is not limited to each of the above embodiments, but the overall shape, the shape of each component, the number of each component, the material of each component, and the combination thereof It can be changed as appropriate.

It is a perspective view of the decomposition | disassembly state explaining the fuel cell unit which uses the separator for fuel cells of this invention as a structural member. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining one Embodiment of the separator for fuel cells of this invention, Comprising: It is each sectional drawing (b)-(e) of 4 forms from which the top view (a) and detail differ of a separator. It is a figure explaining other embodiment of the separator for fuel cells of this invention, Comprising: It is each sectional drawing (a)-(i) of three forms from which a detail differs. FIG. 9 is a diagram for explaining still another embodiment of the fuel cell separator of the present invention, and is a plan view of each separator showing a form in which the filling member and the current collector are entirely overlapped and partially overlapped (a) ) (D), (b) and (e), respectively, and cross-sectional views (c) and (f) of the fuel cell unit. It is a figure explaining other embodiment of the separator for fuel cells of this invention, Comprising: Each sectional drawing (a) (c) of two forms from which details differ, and each sectional drawing (b) of each principal part of each form ( d). It is a figure explaining other embodiment of the separator for fuel cells of the present invention, and is a top view (a) and a sectional view (b) of a separator. It is a figure explaining other embodiment of the separator for fuel cells of the present invention, and is a top view (a) and a sectional view (b) of a separator. It is a figure explaining other embodiment of the separator for fuel cells of this invention, Comprising: In each perspective view (a) (c) (e) and each sectional drawing (b) (d) of three forms from which a detail differs is there. It is a figure explaining other embodiment of the separator for fuel cells of the present invention, and is a sectional view with an enlarged drawing of a separator. It is a figure explaining other embodiment of the separator for fuel cells of the present invention, and is a top view (a) and a sectional view (b) of a separator. It is a figure explaining other embodiment of the separator for fuel cells of the present invention, and is a sectional view of a separator.

Explanation of symbols

S1 to S10 Separator U Fuel cell unit 1 Single cell 2 Cell plate 3 Separator 6 Fuel electrode side current collector 7 8 Flow path component 7a 8a Packaging component 7b 6b Filling component 11 Filling member 12 Packaging member 12a Thin plate (packaging member)
12b Peripheral member (packaging member)
12c Flexible part (variable structure)
12d Inner peripheral member (packaging member)
14 Welding prevention layer 15 Coating

Claims (13)

A separator of a fuel cell unit comprising a plate-like separator that forms a gas flow path between a single cell and a single cell,
A filling member made of a material having higher thermal conductivity than the Cr-containing Fe alloy;
A packaging member made of any one of a material having higher corrosion resistance and oxidation resistance than a Cr-containing Fe alloy and a material having higher corrosion resistance and oxidation resistance than a filling member;
A separator for a fuel cell, wherein a filling member is hermetically packaged with a packaging member.   The fuel cell separator according to claim 1, wherein the packaging member and the filling member are in close contact with each other.   The fuel cell separator according to claim 2, wherein the packaging member has a variable structure for following the thermal deformation of the filling member and maintaining a close contact state between the packaging member and the filling member.   The fuel cell unit accommodates an elastic current collector between the cell plate and the separator, and the region of the filling member is at least a part of the region of the current collector in the thickness direction of the separator. The fuel cell separator according to claim 1, wherein the fuel cell separator overlaps with the fuel cell separator.   The separator for a fuel cell according to any one of claims 1 to 4, wherein a thermal expansion coefficient of the filling member is larger than a thermal expansion coefficient of the packaging member.   6. A disc-shaped separator having a central hole, wherein the packaging member includes an outer peripheral member made of a material having a higher coefficient of thermal expansion than that of the main body at an outer peripheral end portion thereof. The separator for fuel cells according to any one of the above   2. A disc-shaped separator having a central hole, wherein the packaging member includes an inner peripheral member made of a material having a lower coefficient of thermal expansion than that of the main body at the inner peripheral end thereof. The separator for fuel cells according to any one of -6.   The fuel cell separator according to any one of claims 1 to 7, wherein a flow path component for forming a gas flow path between the cell plate and the cell plate is integrally provided.   9. The fuel cell separator according to claim 8, wherein the flow path component includes a packaging component made of the same material as the packaging member and a filling component made of the same material as the filling member.   10. The fuel cell separator according to claim 9, wherein the thermal expansion coefficient of the filling part is larger than the thermal expansion coefficient of the packaging part.   The fuel cell separator according to claim 1, further comprising a welding prevention layer between the filling member and the packaging member to prevent welding of both.   The fuel cell separator according to any one of claims 1 to 11, wherein a film having a hydrogen diffusion coefficient smaller than that of the packaging member is formed on the outer surface of the packaging member.   A solid oxide fuel cell comprising a stack of fuel cell units each including the separator according to any one of claims 1 to 12.

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