JP4918249B2 - Solid polymer electrolyte membrane electrode assembly - Google Patents

Description

  The present invention relates to a solid polymer electrolyte membrane electrode assembly, a method for producing the same, and a solid polymer electrolyte fuel cell using the assembly.

  FIG. 6 shows a schematic structure of a main part of a conventional solid polymer electrolyte fuel cell.

As shown in FIG. 6, on one side of the solid polymer electrolyte membrane 111 having proton (H ⁺ ) conductivity, a fuel having conductivity and gas permeability containing a catalytic metal such as a Pt—Ru system. An electrode film 112 is provided. On the other surface side of the solid polymer electrolyte membrane 111, an oxide electrode film 113 containing a catalytic metal such as Pt and having conductivity and gas permeability is disposed.

  The fuel electrode membrane 112 side and the other surface side of the solid polymer electrolyte membrane electrode assembly (cell) composed of the solid polymer electrolyte membrane 111, fuel electrode membrane 112, oxide electrode membrane 113, etc. A gas diffusion layer 114 having conductivity and gas diffusibility is provided on the side of the oxide electrode film 113 that is an electrode film. On one side and the other side of the cell in which the gas diffusion layer 114 is disposed, a fuel gas flow passage 115a such as hydrogen gas is formed on one side, and an oxidizing gas flow passage 115b such as air or oxygen is formed. Are formed on the other surface, and conductive separators 115 are respectively disposed.

  A stack of solid polymer electrolyte fuel cells 110 is formed by stacking a plurality of these members 111-115 while sandwiching the cells (111-113) between the gas diffusion layers 114 and the separators 115 in this way. .

In such a polymer electrolyte fuel cell 110, when fuel gas is supplied to the fuel gas flow passage 115a of the separator 115 and oxidization gas is supplied to the oxidation gas flow passage 115b of the separator 115, the fuel gas is By being supplied to the fuel electrode film 112 while being diffused by the gas diffusion layer 114, and by supplying the oxidizing gas to the oxide electrode film 113 while being diffused by the gas diffusion layer 114, the fuel gas and the oxidizing gas are supplied to the cell. Proton (H ⁺ ) generated from hydrogen gas on the fuel electrode membrane 112 side in an electrochemical reaction moves in the solid polymer electrolyte membrane 111 to the oxidation electrode membrane 113 side, and hydrogen on the fuel electrode membrane 112 side. electrons generated from a gas (e ^-) is via an external electrical circuit from the gas diffusion layer 114 and the separator 115 oxide electrode film 113 side It flows through the separator 115 and the gas diffusion layer 114. Thereby, it is possible to generate electric power while generating water by reacting oxygen with the protons and the electrons on the oxide electrode film 113 side.

JP 2005-032681 A

  In the solid polymer electrolyte fuel cell 110 as described above, it is strongly required to improve the current-voltage characteristics as much as possible in order to improve the power density and the cell efficiency as much as possible. For this reason, various attempts have been made to improve the performance of the catalyst added to the fuel electrode membrane 112 and the oxide electrode membrane 113. However, the development does not only require a large cost, but it is difficult to obtain the desired performance. It has become a situation.

  For this reason, the present invention avoids newly developing a high-performance catalyst with a high degree of difficulty and development risk, and can improve the current-voltage characteristics without spending a great deal of cost. It is an object of the present invention to provide a molecular electrolyte membrane electrode assembly, a production method thereof, and a solid polymer electrolyte fuel cell using the assembly.

The solid polymer electrolyte membrane electrode assembly according to the first invention for solving the above-described problem is a solid polymer electrolyte membrane electrode assembly in which a solid polymer electrolyte membrane is sandwiched between a fuel electrode membrane and an oxide electrode membrane. In the body, the oxide electrode film has a base layer in contact with the solid polymer electrolyte membrane, and a plurality of striped protrusions and depressions formed on the base layer and having irregularities in the thickness direction. Ri Do and a layer, wherein the protrusion of the additional layer and the boundary position b1 in the basal layer of the recess, said solid high a widthwise center position of the protrusion of the additional layer and the underlying layer The length connecting the position a1 projected on the interface with the molecular electrolyte membrane forms the gas diffusion maximum length E1 of the oxidizing gas with respect to the oxidation electrode film, and the base layer thickness A1 and the additional layer thickness B1. And the total thickness (A1 + B1) is greater than the maximum gas diffusion length E1 Listen further, the following equation (11), characterized in that it satisfies the relation (12).
f1 (i / α1) −f1 (i)
−ρ1i [A1 + {B1 (C1 + D1) / D1} −E1]> 0 (11)
α1 = {A1 (C1 + D1) + B1D1} / {E1 (C1 + D1)} (12)
Here, f1 (i) is a current-voltage characteristic function after correction of ohmic resistance of a reference oxide electrode film made of the same material as the oxide electrode film and having a uniform thickness of the maximum gas diffusion length E1 , ρ1 the resistivity of the reference oxide electrode film, i is the current density, C1 is the length of the recess between the projections adjacent the additional layer of oxide electrode film, D1, an additional layer of oxide electrode film It is the length of the projection part between the adjacent recessed parts.

A solid polymer electrolyte membrane electrode assembly according to a second invention is the solid polymer electrolyte membrane electrode assembly according to the first invention, wherein the fuel electrode membrane is formed on a base layer in contact with the solid polymer electrolyte membrane, and on the base layer. Ri Do and a thickness protrusion stripe-shaped forming an uneven shape in the direction and the recess includes a plurality of additional layers Te, the boundary position b2 in the basal layer of the protrusion and the recess of the additional layer The length connecting the center position in the width direction of the protrusion of the additional layer to the position a2 projected on the interface between the base layer and the solid polymer electrolyte membrane is the maximum gas diffusion of the oxidizing gas with respect to the oxidation electrode film. The total thickness (A2 + B2) of the base layer thickness A2 and the additional layer thickness B2 together with the length E2 is larger than the maximum gas diffusion length E2, and the following formula (21), The relationship (22) is satisfied.
f2 (i / α2) −f2 (i)
−ρ2i [A2 + {B2 (C2 + D2) / D2} −E2]> 0 (21)
α2 = {A2 (C2 + D2) + B2D2} / {E2 (C2 + D2)} (22)
However, f2 (i), the conjunction consisting fuel electrode film of the same material of the reference fuel electrode film having a uniform thickness of the gas diffusion maximum length E2, ohmic resistance losses corrected current - voltage characteristic function, [rho] 2 the resistivity of the reference fuel electrode film, i is the current density, C2, the length of the recess between the projections adjacent the additional layer of fuel electrode film, D2, an additional layer of fuel electrode film It is the length of the projection part between the adjacent recessed parts.

A solid polymer electrolyte membrane electrode assembly according to a third invention is a solid polymer electrolyte membrane electrode assembly in which a solid polymer electrolyte membrane is sandwiched between a fuel electrode membrane and an oxide electrode membrane, wherein the fuel electrode membrane comprises: the solid and base layer in contact with the polymer electrolyte membrane, Ri Do from an additional layer having a plurality of projections and recesses of the stripe-shaped forming an uneven shape in the thickness direction is formed on the foundation layer, the additional layer The projecting portion of the projection and the depression on the base layer b2 and the center position in the width direction of the projection of the additional layer are projected onto the interface between the base layer and the solid polymer electrolyte membrane. The length connecting the position a2 forms the gas diffusion maximum length E2 of the oxidizing gas with respect to the oxide electrode film, and the total thickness (A2 + B2) of the base layer thickness A2 and the additional layer thickness B2 is the gas diffusion greater than the maximum length E2, further the following equation (21 , Characterized in that it satisfies the relation (22).
f2 (i / α2) −f2 (i)
−ρ2i [A2 + {B2 (C2 + D2) / D2} −E2]> 0 (21)
α2 = {A2 (C2 + D2) + B2D2} / {E2 (C2 + D2)} (22)
However, f2 (i), the conjunction consisting fuel electrode film of the same material of the reference fuel electrode film having a uniform thickness of the gas diffusion maximum length E2, ohmic resistance losses corrected current - voltage characteristic function, [rho] 2 the resistivity of the reference fuel electrode film, i is the current density, C2, the length of the recess between the projections adjacent the additional layer of fuel electrode film, D2, an additional layer of fuel electrode film It is the length of the projection part between the adjacent recessed parts.

Further, in order to solve the aforementioned problems, the manufacturing method of the solid polymer electrolyte membrane electrode assembly according to a fourth invention, in the manufacturing method of the solid polymer electrolyte membrane electrode assembly according to the first-th invention A catalyst for supporting an oxide electrode film in which a carbon powder carrying a catalyst and a binder are dispersed in a solvent is provided on one surface of the solid polymer electrolyte film and dried to form the base of the oxide electrode film. After forming the layer, a masking member having a shape corresponding to the depression of the additional layer of the oxidation electrode film is disposed on the base layer, and further provided with a slurry for the oxidation electrode film, the masking By removing the member and drying, the oxide electrode film having the additional layer on the base layer is provided on the surface of the solid polymer electrolyte membrane.

Method for producing a solid polymer electrolyte membrane electrode assembly according to a fifth invention is a manufacturing method of the solid polymer electrolyte membrane electrode assembly according to the first-th invention, a carbon powder supporting a catalyst A slurry for an oxide electrode film in which a binder is dispersed in a solvent is provided on one surface of the solid polymer electrolyte membrane and dried to form a prototype layer of the oxide electrode film. The oxide layer having the additional layer on the base layer is provided on one surface of the solid polymer electrolyte membrane by pressing a mold member having a shape corresponding to the depression of the additional layer against the original layer. It is characterized by that.

Method for producing a solid polymer electrolyte membrane electrode assembly according to a sixth invention is a third-th method for producing a solid polymer electrolyte membrane electrode assembly according to the invention, a carbon powder supporting a catalyst A fuel electrode membrane slurry in which a binder is dispersed in a solvent is provided on one surface of the solid polymer electrolyte membrane and dried to form the base layer of the fuel electrode membrane. A masking member having a shape corresponding to the recess of the additional layer is disposed on the base layer, and further provided with a slurry for the fuel electrode membrane, and then the masking member is removed and dried. The fuel electrode membrane having the additional layer on a base layer is provided on one surface of the solid polymer electrolyte membrane.

Method for producing a solid polymer electrolyte membrane electrode assembly according to a seventh aspect of the present invention, in the third th method for producing a solid polymer electrolyte membrane electrode assembly according to the invention, a carbon powder supporting a catalyst A fuel electrode membrane slurry in which a binder is dispersed in a solvent is provided on one surface of the solid polymer electrolyte membrane and dried to form a prototype layer of the fuel electrode membrane. The fuel electrode membrane having the additional layer on the base layer is provided on one surface of the solid polymer electrolyte membrane by pressing a mold member having a shape corresponding to the depression of the additional layer against the prototype layer. It is characterized by that.

A method for producing a solid polymer electrolyte membrane electrode assembly according to the eighth invention is a method for producing a solid polymer electrolyte membrane electrode assembly according to the second invention, comprising a carbon powder carrying a catalyst and After forming a base layer of the oxidation electrode film by providing a slurry for the oxidation electrode film in which a binder is dispersed in a solvent and drying the slurry on one surface of the solid polymer electrolyte membrane, A masking member having a shape corresponding to the depression of the additional layer is disposed on the base layer, and further provided with a slurry for the oxide electrode film, and then the masking member is removed and dried. A slurry for a fuel electrode membrane in which the oxide electrode membrane having the additional layer on the base layer is provided on the surface of the solid polymer electrolyte membrane, and a carbon powder carrying a catalyst and a binder are dispersed in a solvent. The solid polymer battery After forming the base layer of the fuel electrode membrane by providing on the remaining surface of the membrane and drying, a masking member having a shape corresponding to the recess of the additional layer of the fuel electrode membrane is formed on the base layer The fuel electrode membrane having the additional layer on the base layer is removed from the solid polymer electrolyte membrane by disposing and further providing a slurry for the fuel electrode membrane and then drying the masking member. It is provided on the remaining surface.

A method for producing a solid polymer electrolyte membrane / electrode assembly according to a ninth invention is a method for producing a solid polymer electrolyte membrane / electrode assembly according to the second invention, comprising a carbon powder carrying a catalyst and A slurry for an oxide electrode film in which a binder is dispersed in a solvent is provided on one surface of the solid polymer electrolyte membrane and dried to form a prototype layer of the oxide electrode film. The oxide layer having the additional layer on the base layer is provided on one surface of the solid polymer electrolyte membrane by pressing a mold member having a shape corresponding to the depression of the additional layer against the original layer. In addition, a fuel electrode membrane slurry in which carbon powder supporting a catalyst and a binder are dispersed in a solvent is provided on the remaining surface of the solid polymer electrolyte membrane and dried to form a prototype layer of the fuel electrode membrane. After forming, the additional layer of the fuel electrode membrane The fuel electrode membrane having the additional layer on the base layer is provided on the remaining surface of the solid polymer electrolyte membrane by pressing a mold member having a shape corresponding to the recess to the prototype layer. And

Moreover, a solid polymer electrolyte fuel cell according to the tenth invention for solving the above-mentioned problem is a solid polymer electrolyte membrane electrode assembly according to any one of the first to third inventions, A gas diffusion layer disposed in pairs so as to sandwich the solid polymer electrolyte membrane electrode assembly, and a pair so as to sandwich the solid polymer electrolyte membrane electrode assembly via the gas diffusion layer And a separator to be disposed.

  According to the solid polymer electrolyte membrane electrode assembly according to the present invention, since the electrode membrane has a structure satisfying the above-described relationship, a high-performance catalyst development with high difficulty and development risk is newly performed. By avoiding this, the current-voltage characteristics can be greatly improved as compared with the prior art without spending a great deal of cost.

  For this reason, according to the solid polymer electrolyte fuel cell according to the present invention, it is possible to easily and significantly reduce the power generation performance at a low cost.

  Moreover, according to the manufacturing method of the solid polymer electrolyte membrane electrode assembly which concerns on this invention, the solid polymer electrolyte membrane electrode assembly which has the effect as mentioned above can be manufactured easily.

  An embodiment of a solid polymer electrolyte membrane electrode assembly according to the present invention, a production method thereof, and a solid polymer electrolyte fuel cell using the assembly will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of a main part of a solid polymer electrolyte fuel cell, FIG. 2 is a partially extracted enlarged perspective view of an electrode membrane of the solid polymer electrolyte membrane electrode assembly of FIG. 1, and FIG. FIG. 4 is an explanatory diagram of the method for producing the solid polymer electrolyte membrane electrode assembly of FIG. 1, and FIG. 5 is a graph showing the current-voltage characteristics of the electrode membrane. . Note that the present invention is not limited to the embodiments described below.

As shown in FIG. 1, on one side of a solid polymer electrolyte membrane 11 having proton (H ⁺ ) conductivity, a fuel having conductivity and gas permeability containing a catalytic metal such as a Pt—Ru system. An electrode film 12 is provided. On the other side of the solid polymer electrolyte membrane 11, an oxide electrode membrane 13 containing a catalytic metal such as Pt and having conductivity and gas permeability is disposed.

  The fuel electrode membrane 12 side and the other surface side which are electrode membranes on one side of the solid polymer electrolyte membrane electrode assembly (cell) comprising the solid polymer electrolyte membrane 11, the fuel electrode membrane 12, the oxide electrode membrane 13 and the like. A gas diffusion layer 14 having electrical conductivity and gas diffusibility is provided on the side of the oxide electrode film 13 that is an electrode film. On one side and the other side of the cell where the gas diffusion layer 14 is disposed, a fuel gas flow passage 15a such as hydrogen gas is formed on one side, and an oxidizing gas flow passage 15b such as air or oxygen is formed. Are formed on the other surface and electrically conductive separators 15 are respectively disposed.

  As shown in FIGS. 1 and 2, the fuel electrode membrane 12 and the oxidation electrode membrane 13 are located on the solid polymer electrolyte membrane 11 side and are in contact with the entire solid polymer electrolyte membrane 11. And a plurality of striped protrusions 12ba and 13ba and depressions 12bb and 13bb formed on the base layers 12a and 13a so as to be located on the gas diffusion layer 14 side and having an uneven shape in the thickness direction. It consists of layers 12b and 13b.

  Here, the current-voltage characteristic function of the reference oxide electrode film 3 (see FIG. 3A) made of the same material as that of the oxide electrode film 13 and having a uniform thickness E1 (see FIG. 3A) after correcting the ohmic resistance loss is represented by f1 (i ), The resistivity of the reference oxide film 3 is ρ1, i is the current density, the thickness of the base layer 13a is A1 in the oxide film 13, and the thickness of the additional layer 13b (the protrusion) The height of the portion 13ba or the depth of the recess 13bb) is B1, the length of the recess 13bb between the adjacent protrusions 13ba is C1, and the length between the adjacent recesses 13bb is When the length of the protruding portion 13ba is D1, the oxide electrode film 13 has a relationship satisfying the following expressions (11) and (12).

f1 (i / α1) −f1 (i)
−ρ1i [A1 + {B1 (C1 + D1) / D1} −E1]> 0 (11)
α1 = {A1 (C1 + D1) + B1D1} / {E1 (C1 + D1)} (12)

Note that the boundary position b1 between the protrusion 13ba and the recess 13bb on the base layer 13a and the center position in the width direction of the protrusion 13ba are the interface between the base layer 13a and the solid polymer electrolyte membrane 11. The length connecting the position a1 projected onto the reference electrode is equal to the thickness E1 of the reference oxide electrode film 3.

  On the other hand, the current-voltage characteristic function of the reference oxide electrode film 2 (see FIG. 3B) having a uniform thickness E2 made of the same material as that of the fuel electrode film 12 after correction of the ohmic resistance loss is represented by f2 (i). The resistivity of the reference fuel electrode membrane 2 is ρ2, i is the current density, the thickness of the base layer 12a in the fuel electrode membrane 12 is A2, and the thickness of the additional layer 12b (the protrusion The height of 12ba or the depth of the recess 12bb) is B2, the length of the recess 12bb between the adjacent projections 12ba is C2, and the projection between the adjacent recesses 12bb. When the length of the portion 12ba is D2, the fuel electrode membrane 12 has a relationship satisfying the following expressions (21) and (22).

f2 (i / α2) −f2 (i)
−ρ2i [A2 + {B2 (C2 + D2) / D2} −E2]> 0 (21)
α2 = {A2 (C2 + D2) + B2D2} / {E2 (C2 + D2)} (22)

Note that the boundary position b2 of the protrusion 12ba and the recess 12bb on the base layer 12a and the center position in the width direction of the protrusion 12ba are the interface between the base layer 12a and the solid polymer electrolyte membrane 11. The length connecting with the position a2 projected onto is equal to the thickness E2 of the reference fuel electrode membrane.

  A cell having such a structure includes, for example, an oxide electrode film in which a carbon powder supporting a Pt-based catalyst and a binder made of a polymer electrolyte such as a cation exchanger polymer are dispersed in a solvent such as ethanol. The base layer 13a of the oxide electrode film 13 is prepared by spraying or applying the slurry for the oxide electrode film on the other surface of the solid polymer electrolyte membrane 11 in a predetermined amount and drying it. 4, a masking member M1 having a shape corresponding to the recess 13bb of the additional layer 13b of the oxide electrode film 13 is disposed on the base layer 13a as shown in FIG. After the film slurry 13L is further sprayed from the spray nozzle N1 or the like, the masking member M1 is removed and dried, whereby the oxide electrode film 13 having the additional layer 13b on the base layer 13a is obtained. The solid polymer electrolyte membrane 11 is provided on the other surface, and a carbon powder carrying a Pt-Ru catalyst and a binder made of a polymer electrolyte such as a cation exchanger polymer are dispersed in a solvent such as ethanol. Thus, a slurry for the fuel electrode membrane is produced, and this fuel electrode membrane slurry is sprayed or applied in a predetermined amount on one surface of the solid polymer electrolyte membrane 11 and dried to dry the fuel electrode membrane 12. After the base layer 12a is formed, as shown in FIG. 4, a masking member M2 having a shape corresponding to the recess 12bb of the additional layer 12b of the fuel electrode membrane 12 is disposed on the base layer 12a. Then, after the slurry 12L for the fuel electrode membrane is further sprayed from the spray nozzle N2 or the like, the masking member M2 is removed and dried, whereby the additional layer 12b is formed on the base layer 12a. The fuel electrode film 12 to by providing on one surface of the solid polymer electrolyte membrane 11, can be easily obtained.

  Further, for example, after forming the original layer of the oxidation electrode film 13 by providing the slurry for the oxidation electrode film by spraying or coating it in a predetermined amount on the other surface of the solid polymer electrolyte membrane 11 and drying it, By pressing a mold member having a shape corresponding to the depression 13bb of the additional layer 13b of the oxide electrode film 13 against the original layer for a predetermined time, the oxide electrode film 13 having the additional layer 13b on the base layer 13a is formed into the solid layer. The fuel electrode membrane 11 is provided on the other surface of the polymer electrolyte membrane 11, and the slurry for the fuel electrode membrane is sprayed or applied in a predetermined amount on one surface of the solid polymer electrolyte membrane 11 and dried to dry the fuel electrode membrane 12. After forming the prototype layer, the additional layer 12b is formed on the base layer 12a by pressing a mold member having a shape corresponding to the depression 12bb of the additional layer 12b of the fuel electrode membrane 12 against the prototype layer for a predetermined time. With fuel electrode membrane 12 on top Also be provided on the other surface of the solid polymer electrolyte membrane 11, it can be easily obtained.

  A stack of the solid polymer electrolyte fuel cell 10 is formed by stacking a plurality of the members 11-15 while sandwiching the cell (11-13) between the gas diffusion layer 14 and the separator 15. The

In such a solid polymer electrolyte fuel cell 10, when fuel gas is supplied to the fuel gas flow passage 15 a of the separator 15 and oxidization gas is supplied to the oxidation gas flow passage 15 b of the separator 15, the fuel gas is The fuel gas and the oxidizing gas are supplied to the fuel electrode film 12 while being diffused in the gas diffusion layer 14, and the oxidizing gas is supplied to the oxide electrode film 13 while being diffused in the gas diffusion layer 14. Proton (H ⁺ ) generated from hydrogen gas on the fuel electrode membrane 12 side by electrochemical reaction moves in the solid polymer electrolyte membrane 11 to the oxidation electrode membrane 13 side, and hydrogen on the fuel electrode membrane 12 side. electrons generated from a gas (e ^-) separator 15 and the gas diffusion layer 1 to the oxide electrode film 13 side via an external electric circuit through the gas diffusion layer 14 and the separator 15 Flowing through. Thereby, it is possible to generate electric power while generating water by reacting oxygen with the protons and the electrons on the oxide electrode film 13 side.

  At this time, since the fuel electrode film 12 and the oxide electrode film 13 have the above-described structure having a relationship satisfying the above formulas (11), (12), (21), and (22), the degree of difficulty In addition to avoiding new development of high-performance catalysts with high development risk, current-voltage characteristics can be improved without spending significant costs, and it is easy to significantly improve power generation performance Can be realized at low cost. The reason for this will be described below.

  The performance of the electrode film mainly depends on the permeability of the source gas, the reaction amount between the source gas and the catalyst, the ohmic resistance loss, and the like. The permeability of the source gas is mainly due to the type and blending ratio of the polymer electrolyte such as the cation exchanger polymer used as the binder, the type and content of the catalyst, the thickness of the electrode film, and the like. The amount of reaction between the source gas and the catalyst mainly depends on the type and content of the catalyst, the permeability of the source gas based on the type and blending ratio of the polymer electrolyte such as the cation exchanger polymer used as the binder, and the type of the source gas. Determined by etc. The ohmic resistance loss is determined by the type of catalyst, the content of the catalyst, the type and blending ratio of a polymer electrolyte such as a cation exchanger polymer used as a binder, the thickness of the electrode film, and the like.

  In other words, when the type of catalyst to be used, the material of the binder, the type of raw material gas, etc. are determined, the optimum values such as the content and thickness of the catalyst that can achieve the highest performance are naturally determined. It was.

  For this reason, while aiming to improve the performance of the electrode film by improving the performance of the catalyst to be added to the electrode film, not only does it cost a lot of development, but also the desired performance is obtained. This is a difficult situation.

  Therefore, as a result of various studies by the present inventors, by increasing the catalyst content per unit apparent area, the amount of voltage that is improved as the current density is decreased due to the increase in the total surface area of the reaction can be determined. If the amount of the catalyst per area can be increased, the voltage can be made larger than the voltage that decreases as the ohmic resistance loss increases due to the increase in thickness. Even if it is a catalyst, a binder, or the like, the present invention has been completed on the assumption that the performance can be improved over the conventional electrode film.

  In other words, based on the type of catalyst used, the material of the binder, the type of raw material gas, etc., the maximum length of the electrode film that can spread the raw material gas to all positions inside the electrode film as a whole as a whole. Voltage drop due to increased ohmic resistance loss caused by increasing the catalyst content per unit apparent area without increasing the gas diffusion resistance, but with a thickness greater than the thickness (maximum gas diffusion length) The size of the electrode film is set so that the amount of voltage improvement accompanying the decrease in current density is larger than the amount.

  A specific example of this is the structure shown in FIGS. 1 and 2 and the like that satisfy the relationships of the equations (11), (12), (21), and (22) as described above. The above formulas (11), (12), (21), and (22) will be described below.

  First, “Overall, it has a thickness larger than the maximum gas diffusion length, but does not increase the gas diffusion resistance, but increases the ohmic resistance loss caused by increasing the catalyst content per unit apparent area. As the shape of the electrode film capable of making the voltage improvement amount accompanying the decrease in the current density larger than the accompanying voltage drop amount, as shown in FIGS. Additional layers 12b, 13b having a plurality of protrusions 12ba, 13ba and recesses 12bb, 13bb are formed on the base layers 12a, 13a, and the thicknesses A1, A2 of the base layers 12a, 13a of the electrode films 12, 13 are formed. Further, a structure in which the total thickness (A1 + B1, A2 + B2) of the additional layers 12b and 13b and the thicknesses B1 and B2 is larger than the maximum gas diffusion length can be considered.

  In the striped structure shown in FIGS. 1 and 2, the values of E1 and E2 used in the equations (11), (12), (21), and (22) are the maximum gas diffusion length. `` By increasing the catalyst content per unit apparent area, the amount of voltage that increases as the current density decreases due to the increase in the total surface area of the reaction, the catalyst content per unit apparent area By increasing the voltage, it is possible to maximize the voltage without decreasing the gas diffusion resistance by increasing the voltage amount that decreases with the increase in ohmic resistance loss due to the increase in thickness.

  In addition, “increasing the amount of voltage improvement due to the decrease in current density over the amount of voltage decrease due to the increase in ohmic resistance loss caused by increasing the content of the catalyst per unit apparent area” It can be expressed by equation (1).

δi = βi−γi> 0 (1)

  Here, δi is a voltage improvement amount at the current density i, βi is a voltage improvement amount generated by increasing the content of the catalyst per unit apparent area at the current density i, and γi is a current density i. Is the amount of increase in ohmic resistance loss caused by increasing the content of the catalyst per unit apparent area.

  This βi can be further expressed by the following equations (2) and (3).

βi = f (i / α) −f (i) (2)
α = {A (C + D) + BD} / {E (C + D)} (3)

  In addition, f (i) is a current-voltage characteristic function after correcting the ohmic resistance loss of the electrode film before increasing the catalyst content per unit apparent area, and f (i / α) is per unit apparent area. 6 is a current-voltage characteristic function of the electrode film after correcting the ohmic resistance loss after increasing the content of the catalyst (see FIG. 5).

  Α is the volume increase ratio of the electrode film after increasing the catalyst content per unit apparent area before increasing, A is the thickness of the base layers 12a and 13a, and B is the additional layer. The thickness of 12b, 13b (the height of the protrusions 12ba, 13ba or the depth of the recesses 12bb, 13bb), C is the distance between the adjacent protrusions 12ba, 13ba. The length D is the length of the protrusions 12ba and 13ba between the adjacent recesses 12bb and 13bb.

  On the other hand, the γi can be further expressed by the following formula (4).

γi = RaI−RbI (4)

  Ra is the ohmic resistance loss of the electrode film after increasing the catalyst content per unit apparent area, and Rb is the ohmic resistance loss of the electrode film before increasing the catalyst content per unit apparent area. , I are current values (see FIG. 5).

  Here, the thickness of the electrode film before increasing the catalyst content per unit apparent area, that is, the conventional flat electrode film, is usually set to the maximum gas diffusion length. Therefore, if the volume is simply increased so as to form an uneven shape on a conventional flat electrode film whose thickness is set to the maximum gas diffusion length, the position b1, b2 and the position a1, shown in FIG. The lengths E1 and E2 connecting a2 become longer than the maximum gas diffusion length, and it becomes difficult to spread the source gas without delay in all positions inside the electrode film.

  Therefore, as described above, the lengths E1 and E2 connecting the positions b1 and b2 and the positions a1 and a2 shown in FIG. 1 are the gas diffusion maximum lengths, and the thickness is the gas diffusion maximum length. As the reference electrode films 2 and 3 (thickness E1 and E2) as shown in FIG. 3, the current-voltage characteristic function after correcting the ohmic resistance loss of the reference electrode films 2 and 3 as shown in FIG. By increasing the catalyst content per unit apparent area by increasing the catalyst content per unit apparent area, the amount of voltage that increases with decreasing current density due to the increase in the total surface area of the reaction. By increasing the amount, it is possible to maximize the voltage amount that decreases with the increase in ohmic resistance loss due to the increase in thickness without increasing the gas diffusion resistance. Become.

  That is, the ohmic resistance loss of the base layers 12a and 13a is Rc, the ohmic resistance loss of the additional layers 12b and 13b is Rd, the ohmic resistance loss of the reference electrode electrodes 2 and 3 is Re, and the area of the electrode film is S By setting the resistivity of the electrode film to ρ, the above formula (4) can be expressed by the following formula (5).

γi = RcI + RdI−ReI
= Ρ (I / S) [A + {B (C + D) / D} −E]
= Ρi [A + {B (C + D) / D} −E] (5)

  Therefore, the formula (1) is expressed by the following formula (6) by substituting the formulas (2) and (5).

f (i / α) −f (i)
-Ρi [A + {B (C + D) / D} -E]> 0 (6)

  That is, by satisfying the relationship of the above formulas (3) and (6), βi can be made larger than γi as can be seen from the description of FIG. Can be improved.

  Therefore, according to the present embodiment, even a conventionally used catalyst, binder, or the like can improve performance compared to a conventional electrode film.

  In the present embodiment, the additional layers 12b and 13b having the protrusions 12ba and 13ba are formed on both the fuel electrode film 12 and the oxide electrode film 13 on the base layers 12a and 13a. The power generation performance can be improved as compared with the conventional art only by applying the electrode film having the additional layer formed on the base layer to one of the fuel electrode film and the oxide electrode film. In particular, it is preferable to apply only to the oxide electrode film than to apply only to the fuel electrode film because a more remarkable effect can be obtained.

  In the present embodiment, the case where the values of E1 and E2 are set to the maximum gas diffusion length has been described. However, in the present invention, the values of E1 and E2 are not values set from the maximum gas diffusion length, Is a value set from the thickness of the conventional electrode film (reference electrode film). However, as described above, since the thickness of the target conventional electrode film (reference electrode film) is normally set to the maximum gas diffusion length, the values of E1 and E2 are the maximum gas diffusion length. When the gas diffusion maximum length is set, the performance of the electrode film can be expressed most efficiently, which is the most preferable mode.

  The solid polymer electrolyte membrane electrode assembly according to the present invention, the production method thereof, and the solid polymer electrolyte fuel cell using the assembly are used extremely beneficially in various industries, as is apparent from the above description. be able to.

It is a schematic block diagram of the principal part of embodiment of the solid polymer electrolyte fuel cell using the solid polymer electrolyte membrane electrode assembly which concerns on this invention. It is a partial extraction expansion perspective view of the electrode membrane of the solid polymer electrolyte membrane electrode assembly of FIG. It is explanatory drawing of a reference | standard oxidation electrode film and a reference | standard fuel electrode film. It is explanatory drawing of the manufacturing method of the solid polymer electrolyte membrane electrode assembly of FIG. It is a graph showing the current-voltage characteristic of an electrode film. It is a schematic block diagram of the principal part of an example of the conventional solid polymer electrolyte fuel cell.

Explanation of symbols

2 Reference Fuel Electrode Membrane 3 Reference Oxide Electrode Membrane 10 Solid Polymer Electrolyte Fuel Cell 11 Solid Polymer Electrolyte Membrane 12 Fuel Electrode Membrane 12a Base Layer 12b Additional Layer 12ba Projection 12bb Recessed Part 13 Oxide Electrode Film 13a Base Layer 13b Additional Layer 13ba Projection 13bb Recess 14 Gas diffusion layer 15 Separator 15a Fuel gas flow path 15b Oxidation gas flow path

Claims (10)

In a solid polymer electrolyte membrane electrode assembly in which a solid polymer electrolyte membrane is sandwiched between a fuel electrode membrane and an oxide electrode membrane,
The oxidized electrode film is
A base layer in contact with the solid polymer electrolyte membrane;
Ri additional layer and Tona having a plurality of projections and recesses of the stripe-shaped forming an uneven shape in the thickness direction are formed on said base layer,
The boundary position b1 on the base layer between the protrusion and the recess of the additional layer and the center position in the width direction of the protrusion of the additional layer are the interfaces between the base layer and the solid polymer electrolyte membrane. The length connecting the position a1 projected onto the oxide electrode forms the gas diffusion maximum length E1 of the oxidizing gas with respect to the oxide electrode film,
The total thickness (A1 + B1) of the base layer thickness A1 and the additional layer thickness B1 is larger than the maximum gas diffusion length E1,
A solid polymer electrolyte membrane electrode assembly characterized by satisfying the following formulas (11) and (12):
f1 (i / α1) −f1 (i)
−ρ1i [A1 + {B1 (C1 + D1) / D1} −E1]> 0 (11)
α1 = {A1 (C1 + D1) + B1D1} / {E1 (C1 + D1)} (12)
However,
f1 (i) is a current-voltage characteristic function of the reference oxide electrode film made of the same material as that of the oxide electrode film and having a uniform thickness of the gas diffusion maximum length E1, after correcting the ohmic resistance loss,
ρ1 is the resistivity of the reference oxide electrode film,
i is the current density ,
C1 is the length of the recess between adjacent protrusions of the additional layer of the oxide electrode film,
D1 is the length of the protrusion between adjacent recesses of the additional layer of the oxide electrode film. In claim 1,
The fuel electrode membrane is
A base layer in contact with the solid polymer electrolyte membrane;
Ri additional layer and Tona having a plurality of projections and recesses of the stripe-shaped forming an uneven shape in the thickness direction are formed on said base layer,
The boundary position b2 of the additional layer on the base layer between the protrusion and the recess, and the center position in the width direction of the protrusion on the additional layer are the interfaces between the base layer and the solid polymer electrolyte membrane. The length connecting the position a2 projected on the gas forms the gas diffusion maximum length E2 of the oxidizing gas with respect to the oxidation electrode film,
The total thickness (A2 + B2) of the base layer thickness A2 and the additional layer thickness B2 is larger than the maximum gas diffusion length E2,
A solid polymer electrolyte membrane / electrode assembly satisfying the following formulas (21) and (22):
f2 (i / α2) −f2 (i)
−ρ2i [A2 + {B2 (C2 + D2) / D2} −E2]> 0 (21)
α2 = {A2 (C2 + D2) + B2D2} / {E2 (C2 + D2)} (22)
However,
f2 (i), the conjunction consisting fuel electrode film of the same material of the reference fuel electrode film having a uniform thickness of the gas diffusion maximum length E2, ohmic resistance losses corrected current - voltage characteristic function,
ρ2 is resistivity of the reference fuel electrode film,
i is the current density ,
C2 is the length of the recess between adjacent protrusions of the additional layer of the fuel electrode membrane,
D2 is the length of the protrusion between adjacent recesses of the additional layer of the fuel electrode membrane. In a solid polymer electrolyte membrane electrode assembly in which a solid polymer electrolyte membrane is sandwiched between a fuel electrode membrane and an oxide electrode membrane,
The fuel electrode membrane is
A base layer in contact with the solid polymer electrolyte membrane;
Ri additional layer and Tona having a plurality of projections and recesses of the stripe-shaped forming an uneven shape in the thickness direction are formed on said base layer,
The boundary position b2 of the additional layer on the base layer between the protrusion and the recess, and the center position in the width direction of the protrusion on the additional layer are the interfaces between the base layer and the solid polymer electrolyte membrane. The length connecting the position a2 projected on the gas forms the gas diffusion maximum length E2 of the oxidizing gas with respect to the oxidation electrode film,
The total thickness (A2 + B2) of the base layer thickness A2 and the additional layer thickness B2 is larger than the maximum gas diffusion length E2,
A solid polymer electrolyte membrane / electrode assembly satisfying the following formulas (21) and (22):
f2 (i / α2) −f2 (i)
−ρ2i [A2 + {B2 (C2 + D2) / D2} −E2]> 0 (21)
α2 = {A2 (C2 + D2) + B2D2} / {E2 (C2 + D2)} (22)
However,
f2 (i), the conjunction consisting fuel electrode film of the same material of the reference fuel electrode film having a uniform thickness of the gas diffusion maximum length E2, ohmic resistance losses corrected current - voltage characteristic function,
ρ2 is resistivity of the reference fuel electrode film,
i is the current density ,
C2 is the length of the recess between adjacent protrusions of the additional layer of the fuel electrode membrane,
D2 is the length of the protrusion between adjacent recesses of the additional layer of the fuel electrode membrane. It is a manufacturing method of the solid polymer electrolyte membrane electrode assembly according to claim 1,
Forming the base layer of the oxide electrode film by providing a slurry for the oxide electrode film in which carbon powder supporting a catalyst and a binder are dispersed in a solvent on one surface of the solid polymer electrolyte membrane and drying the slurry. After that, a masking member having a shape corresponding to the depression of the additional layer of the oxide electrode film is disposed on the base layer, and after further providing a slurry for the oxide electrode film, the masking member is removed. Then, the oxide electrode membrane having the additional layer on the base layer is provided on the surface of the solid polymer electrolyte membrane by drying the solid polymer electrolyte membrane electrode assembly. It is a manufacturing method of the solid polymer electrolyte membrane electrode assembly according to claim 1,
An oxide electrode membrane slurry in which a catalyst-supported carbon powder and binder are dispersed in a solvent is provided on one surface of the solid polymer electrolyte membrane and dried to form a prototype layer of the oxide electrode membrane. Thereafter, the mold electrode having a shape corresponding to the concave portion of the additional layer of the oxidation electrode film is pressed against the prototype layer, whereby the oxidation electrode film having the additional layer on the base layer is changed to the solid polymer. A method for producing a solid polymer electrolyte membrane electrode assembly comprising providing on one surface of an electrolyte membrane. A method for producing a solid polymer electrolyte membrane / electrode assembly according to claim 3,
A slurry for a fuel electrode membrane in which carbon powder supporting a catalyst and a binder are dispersed in a solvent is provided on one surface of the solid polymer electrolyte membrane and dried to form the base layer of the fuel electrode membrane After that, a masking member having a shape corresponding to the depression of the additional layer of the fuel electrode membrane is disposed on the base layer, and after further providing a slurry for the fuel electrode membrane, the masking member is removed. And providing the fuel electrode membrane having the additional layer on the base layer on one surface of the solid polymer electrolyte membrane by drying the solid polymer electrolyte membrane electrode assembly. . A method for producing a solid polymer electrolyte membrane / electrode assembly according to claim 3,
A fuel electrode membrane slurry in which a catalyst-supported carbon powder and a binder are dispersed in a solvent is provided on one surface of the solid polymer electrolyte membrane and dried to form a prototype layer of the fuel electrode membrane. Thereafter, the fuel electrode membrane having the additional layer on the base layer is pressed into the solid polymer by pressing a mold member having a shape corresponding to the depression of the additional layer of the fuel electrode membrane against the original layer. A method for producing a solid polymer electrolyte membrane electrode assembly comprising providing on one surface of an electrolyte membrane. It is a manufacturing method of the solid polymer electrolyte membrane electrode assembly according to claim 2,
Forming the base layer of the oxide electrode film by providing a slurry for the oxide electrode film in which carbon powder supporting a catalyst and a binder are dispersed in a solvent on one surface of the solid polymer electrolyte membrane and drying the slurry. After that, a masking member having a shape corresponding to the depression of the additional layer of the oxide electrode film is disposed on the base layer, and after further providing a slurry for the oxide electrode film, the masking member is removed. And drying to provide the oxide electrode film having the additional layer on the base layer on the surface of the solid polymer electrolyte membrane,
A slurry for a fuel electrode membrane in which carbon powder supporting a catalyst and a binder are dispersed in a solvent is provided on the remaining surface of the solid polymer electrolyte membrane and dried to form the base layer of the fuel electrode membrane After that, a masking member having a shape corresponding to the depression of the additional layer of the fuel electrode membrane is disposed on the base layer, and after further providing a slurry for the fuel electrode membrane, the masking member is removed. And providing the fuel electrode membrane having the additional layer on the base layer on the remaining surface of the solid polymer electrolyte membrane by drying the solid polymer electrolyte membrane electrode assembly. . It is a manufacturing method of the solid polymer electrolyte membrane electrode assembly according to claim 2,
An oxide electrode membrane slurry in which a catalyst-supported carbon powder and binder are dispersed in a solvent is provided on one surface of the solid polymer electrolyte membrane and dried to form a prototype layer of the oxide electrode membrane. Thereafter, the mold electrode having a shape corresponding to the concave portion of the additional layer of the oxidation electrode film is pressed against the prototype layer, whereby the oxidation electrode film having the additional layer on the base layer is changed to the solid polymer. Provided on one side of the electrolyte membrane,
A fuel electrode membrane slurry in which carbon powder supporting a catalyst and a binder are dispersed in a solvent is provided on the remaining surface of the solid polymer electrolyte membrane and dried to form a prototype layer of the fuel electrode membrane. Thereafter, the fuel electrode membrane having the additional layer on the base layer is pressed into the solid polymer by pressing a mold member having a shape corresponding to the depression of the additional layer of the fuel electrode membrane against the original layer. A method for producing a solid polymer electrolyte membrane / electrode assembly, which is provided on the remaining surface of an electrolyte membrane. The solid polymer electrolyte membrane electrode assembly according to any one of claims 1 to 3 ,
A gas diffusion layer disposed in pairs so as to sandwich the solid polymer electrolyte membrane electrode assembly; and
A solid polymer electrolyte fuel cell comprising: a separator disposed in a pair so as to sandwich the solid polymer electrolyte membrane electrode assembly through the gas diffusion layer.

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