Fuel cell stack with improved condensate management

Abstract

Fuel cell stack, comprising: a membrane electrode arrangement (115) comprising a cathode (12) and an anode (14), which are catalyst layers and are respectively formed on a first and a second surface of an electrolyte membrane (16), a first separator (304) which is arranged on one side of the membrane electrode arrangement (115), and a second separator (312) which is arranged on the other side of the membrane electrode assembly (115), wherein a gas path (340), through which a gas is released from the cathode or the anode or a gas is supplied to the cathode or the anode, is arranged between the second separator (312) and the membrane electrode arrangement (115) and is formed in a no-reaction zone (330), and wherein the gas path (340) has a flow path extension section and a height of the flow path extension section is greater than a height of a reaction zone (320), wherein the flow path extension section is formed by deforming a shape of the membrane electrode arrangement (115).

Description

Area

[0001] The present invention relates to a fuel cell stack (also called fuel cell stack) which can maintain and improve the performance of a fuel cell by easily releasing a condensate formed by a gas released from an anode or a cathode of a membrane electrode assembly (MEA). background

[0002] A membrane electrode assembly (MEA) is generally located in the middle of a fuel cell stack and has a polymer electrolyte membrane through which hydrogen ions (protons) are transported, and a catalyst layer, such as a cathode and an anode, in which an electrochemical reaction between hydrogen and oxygen takes place, arranged on each of the two sides of the polymer electrolyte membrane.

[0003] A gas diffusion layer and a seal are stacked successively on both sides of the MEA, where the cathode and anode are located. A separator, which has flow fields for supplying fuel and for draining water produced by the reaction, is arranged on the outside of the gas diffusion layer, and an end plate for supporting and fixing the previously described components is connected to each of its two ends.

[0004] At the anode of the fuel cell stack, hydrogen is split into hydrogen ions (protons, H+) and electrons (e-) through an oxidation reaction. The hydrogen ions and electrons are then separated and transferred through the electrolyte membrane and an external circuit to the cathode. At the cathode, an electrochemical reaction involving the hydrogen ions and electrons transferred from the anode, along with oxygen from the air, produces water, and simultaneously generates electrical energy through the flow of electrons.

[0005] The seal, which is arranged between the separator and the MEA, serves as a guide that directs the air and hydrogen to the anode and cathode, and the seal serves as a gas path that releases a reaction gas generated in the catalyst layer.

[0006] Condensate forms in the gas path through which the reaction gas or air flows, and this condensate can block the gas path. Consequently, the efficiency of the fuel cell stack cannot be maintained consistently and may be reduced.

[0007] The above information disclosed in this background section is intended only to improve the understanding of the general background of the invention and should not be regarded as an admission or any indication that this information belongs to the prior art as already known to the person skilled in the art.

[0008] Furthermore, US Patent 2015 / 0093663A1 discloses a fuel cell stack comprising: a membrane electrode assembly, which has a cathode and an anode, which are catalyst layers and are formed on both surfaces of an electrolyte membrane; a first separator, which is arranged on one side of the membrane electrode assembly; and a second separator, which is arranged on the other side of the membrane electrode assembly. A gas path, through which a gas is discharged from or supplied to the cathode or the anode, is arranged between the second separator and the membrane electrode assembly and is formed in a no-reaction zone. The gas path has a flow path expansion section, and the height of the flow path expansion section is greater than the height of the reaction zone. Explanation of the invention

[0009] The present invention is based on the objective of creating a fuel cell stack which can stably maintain and improve the performance of a fuel cell by easily releasing a condensate formed by a reaction gas released from an anode or a cathode of a membrane electrode assembly (MEA).

[0010] To solve this problem, exemplary embodiments of the present invention provide a fuel cell stack according to claim 1. Advantageous further developments are described in the dependent claims.

[0011] A fuel cell stack according to the invention therefore comprises: a membrane electrode assembly, which includes a cathode and an anode, which are catalyst layers and are formed on both surfaces of an electrolyte membrane (e.g., the cathode on a first surface of the electrolyte membrane and the anode on a second surface of the electrolyte membrane); a first separator, which is arranged on one side (e.g., the first surface) of the membrane electrode assembly; and a second separator, which is arranged on the other side (e.g., the second surface) of the membrane electrode assembly. A gas path, through which a gas is released from or supplied to the cathode or the anode, is arranged between the second separator and the membrane electrode assembly and is formed in a no-reaction zone.The gas path has a flow path expansion section, and the height of the flow path expansion section is greater than the height of a reaction zone. According to the invention, the flow path expansion section is formed by deforming a shape of the membrane-electrode assembly.

[0012] The flow path extension section may include a section whose height gradually (e.g., steadily) increases from the gas path.

[0013] The flow path extension section can be formed on a first side surface of the membrane electrode assembly, and the height of a second side surface of the membrane electrode assembly forming the flow path extension section can decrease.

[0014] A gas hole (e.g. a gas passage opening) connected to the gas path may be formed on the second separator.

[0015] The fuel cell stack can further comprise: a first seal (e.g., a first sealing plate, a first sealing flange) located between the membrane electrode assembly and the first separator in the no-reaction zone, and a second seal (e.g., a second sealing plate, a second sealing flange) that corresponds to the first seal (e.g., fits together with it accordingly) and is located between the membrane electrode assembly and the second separator. The flow path expansion section can be designed using the cross-sectional shapes (e.g., profiles) of the first and second seals to deform the shape of the membrane electrode assembly.

[0016] A section which uses cross-sectional shapes of the first seal and the second seal to deform the shape of the membrane electrode assembly can be a secondary seal (e.g. a secondary sealing plate).

[0017] An outer surface of the first seal can have a first thickness, an inner surface of the first seal can have a second thickness which is less than the first thickness, the outer surface of the second seal can have a third thickness, and the inner surface of the second seal can have a fourth thickness which is greater than the third thickness. An inclined section (e.g., a slanted section) located in a region between the outer and inner surfaces can modify the thicknesses of the first and second seals.

[0018] The sum of the first thickness and the third thickness can be equal to the sum of the second thickness and the fourth thickness.

[0019] The gas path can release fuel gas released from the anode or gas released from the cathode.

[0020] A point at which the inclined section begins can be located (e.g., formed) in a region of the gas hole with respect to a direction that is directed from the outer side surface towards the inner side surface.

[0021] The flow path extension section may overlap with part of an area of ​​the gas hole.

[0022] The flow path extension section can overlap with the entire area of ​​the gas hole.

[0023] The second separator can be located on the side where the cathode is situated and can form a channel through which air flows in the reaction zone.

[0024] The second separator can be located on the side where the anode is situated and can form a channel through which a fuel gas flows in the reaction zone.

[0025] The flow path extension section is formed, for example, at an outlet of the gas that is released from the cathode or the anode. Brief description of the drawings Fig. Figure 1 is an exploded view of a fuel cell according to exemplary embodiments of the present invention. Fig. Figure 2 is a perspective view of a fuel cell according to exemplary embodiments of the present invention. Fig. 3a is a cross-sectional view along line DD in Fig. 2, and Fig. 3b is a cross-sectional view along line EE in Fig. 2. Fig. Figure 4 is a cross-sectional view showing a form of a seal according to exemplary embodiments of the present invention. Fig. 5a and Fig. Figure 5b shows partial cross-sectional views of a fuel cell according to the referenced technology. Detailed description

[0026] Exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0027] The sizes and thicknesses of the structures shown in the drawings are selectively provided for the simplicity of the description, so that the present invention is not limited to those shown in the drawings, and the thicknesses may be exaggerated to clarify some parts and areas.

[0028] However, parts which do not relate to the description are omitted to clearly describe the exemplary embodiments of the present invention, and identical reference numerals refer throughout the description to identical or similar elements.

[0029] In the following description, the division of component names into "first", "second", and the like is due to the fact that the component names are mutually identical, and the order of these names is not particularly restricted.

[0030] In exemplary embodiments of the present invention, a gas path 340 of Fig. 3a can be applied equally to a fuel gas outlet and an air outlet. Gas path 340 can be applied uniformly to an outlet side and a supply side.

[0031] Fig. Figure 1 is an exploded view of a fuel cell according to exemplary embodiments of the present invention.

[0032] Referring to Fig. 1 A fuel cell stack (or fuel cell) comprises a membrane electrode assembly (MEA) 115, which includes an electrolyte membrane 10, an anode 14, and a cathode 12, a gas diffusion layer 16 arranged on both sides of the MEA 115 (e.g., a gas diffusion layer on each side of the MEA), a separator (or separator plate) 110 arranged on an outer surface of the gas diffusion layer 16, and a seal (e.g., a sealing plate, a sealing flange) 100 arranged in a no-reaction zone 330 between the separator and the gas diffusion layer. An end plate 30 may be arranged at both ends of the fuel cell stack. The no-reaction zone 330 may be present in the fuel cell stack.

[0033] The electrolyte membrane 10 can provide a path for moving a hydrogen ion, and the anode 14 and the cathode 12 can be a catalyst layer for reactions of hydrogen and oxygen.

[0034] The gas diffusion layer 16 can diffuse air and hydrogen to the cathode 12 and the anode 14, and the separator 110 can form an air path for the flow of air and a gas path for the flow of a fuel gas into a reaction zone 320. The reaction zone 320 can include the MEA 115.

[0035] The seal 100 can be arranged in the no-reaction zone 330 between the separator 110 and the electrolyte membrane 10 or between the separator and the MEA 115, so that the seal forms the gas path 340 of the air or fuel gas which is supplied to or discharged from the reaction zone 320.

[0036] Fig. Figure 2 is a perspective view of a fuel cell according to exemplary embodiments of the present invention.

[0037] With reference to Fig. 2. The seal 100 can be located in the no-reaction area 330 of the fuel cell and can have a main seal 102 and a secondary seal 104. The separator 110 can be located adjacent to the seal 100.

[0038] An air distribution line (e.g., an air distribution duct) 120, a coolant distribution line (e.g., a coolant distribution duct) 130, and a hydrogen distribution line (e.g., a hydrogen distribution duct) 140 can be configured in the no-reaction zone 330 in a stacking direction of the seal 100 and the separator 110. Air can flow through the air distribution line 120, coolant can flow through the coolant distribution line 130, and hydrogen, which is the fuel gas, can flow through the hydrogen distribution line 140.

[0039] The hydrogen, air and coolant can be supplied to a reaction zone 320 of the MEA 115 through the hydrogen distribution line 140, the air distribution line 120 and the coolant distribution line 130, so that the hydrogen, air and coolant can perform a function of generating an electric current and a cooling function.

[0040] In exemplary embodiments of the present invention, the main seal 102 can have a cross-section along line DD and a cross-section along line EE in Fig. 2 and may have the secondary seal 104, or be shown by, only the cross-section along line EE.

[0041] Fig. 3a is a cross-sectional view along line DD in Fig. 2, and Fig. 3b is a cross-sectional view along line EE of Fig. 2.

[0042] Referring to Fig. 1 and Fig. 3a the fuel cell can have the MEA 115, which has the electrolyte membrane 10, the anode 14 and the cathode 12, the gas diffusion layer 16, which is arranged on both sides of the MEA 115 (e.g. a gas diffusion layer on each side of the MEA) and which is arranged in the reaction zone 320, and a first separator 304 and a second separator 312, which are arranged in the no-reaction zone 330 and the reaction zone 320.

[0043] The seal 100 can be located in the no-reaction zone 330 and can have a first seal (e.g. a first sealing plate, a first sealing flange) 100a, which is located between the first separator 304 and the MEA 115, and a second seal (e.g. a second sealing plate, a second sealing flange) 100b, which is located between the second separator 312 and the MEA 115.

[0044] As in Fig. As shown in Figure 3a, a gas hole 142 can be formed in the no-reaction zone 330 of the second separator 312, and the gas flowing through the reaction zone 320 can move through the gas hole 142. The gas can be moved through the gas hole 142 to the reaction zone 320.

[0045] The second seal 100b can form a space corresponding to the gas hole 142 and can form the gas path 340 between the MEA 115 and the second separator 312. The fuel gas or air can move through the gas path 340.

[0046] As one form of the gas path 340, the second separator 312, on which the gas hole 142 is formed, can be designed at (e.g. with) a constant height, and the MEA 115, which faces the second separator 312, can have a form in which the height of the MEA 115 is gradually reduced from the reaction zone 320 towards the no-reaction zone 330 (e.g. a distance between MEA and second separator is increased), then maintained at a constant height (e.g. a distance between MEA and second separator is kept constant), and then gradually increased (e.g. a distance between MEA and second separator is decreased).

[0047] Consequently, a space corresponding to the gas path 340 between the MEA 115 and the first separator 304 can be reduced in size and the height of the gas path 340 can be increased so that condensate formed by the gas produced in the MEA 115 can be easily vented (or discharged).

[0048] In exemplary embodiments of the present invention, a section which is extended by increasing the height of the gas path 340 (thereby, for example, increasing the flow cross-section of the gas path) can be referred to as a flow path extension section.

[0049] Referring to Fig. 3b the seal 100 of the fuel cell can be located in the no-reaction zone 330 and can have the first seal 100a, which is located between the first separator 304 and the MEA 115, and the second seal 100b, which is located between the second separator 312 and the MEA 115.

[0050] As in Fig. As shown in Figure 3b, the shapes (e.g., profiles) of the first seal 100a and the second seal 100b can be modified in an area where the gas hole 142 is not formed. Consequently, the height of the MEA 115 in the no-reaction zone 330 can be adjusted, and the shape of the gas path 340 can be obtained.

[0051] Fig. Figure 4 is a cross-sectional view showing a form of a seal according to exemplary embodiments of the present invention.

[0052] Referring to Fig. 4 The seal 100 has the first seal 100a, which is arranged between the first separator 304 and the MEA 115, and the second seal 100b, which is arranged between the second separator 312 and the MEA 115.

[0053] The first seal 100a and the second seal 100b can have shapes that correspond to each other, with the MEA 115 arranged between them. An outer side surface 400 of the first seal 100a and the second seal 100b (e.g., with respect to the reaction zone 320) can be formed on a side where the hydrogen distribution line 140 (or the air distribution line 120) is formed, and an inner side surface 410 of the first seal 100a and the second seal 100b (e.g., with respect to the reaction zone 320) can be formed on a side where the reaction zone 320 is formed.

[0054] The outer side surface 400 of the first seal 100a can have a first thickness T1, the inner side surface 410 of the first seal 100a can have a second thickness T2, the outer side surface 400 of the second seal 100b can have a third thickness T3, the inner side surface 410 of the second seal 100b can have a fourth thickness T4.

[0055] An inclined (e.g., sloping) section 420 can be formed on the first seal 100a and the second seal 100b. The height of the inclined section 420 can vary from the outer side surface 400 to the inner side surface 410. The remainder of the seal, with the exception of the inclined section 420, can be formed in a horizontal direction (e.g., in a horizontal plane).

[0056] In exemplary embodiments of the present invention, the sum of the first thickness T1 and the third thickness T3 can be equal to the sum of the second thickness T2 and the fourth thickness T4, the fourth thickness T4 can be greater than the third thickness T3, and the sum of the first thickness T1 and the third thickness T3 can be greater than the fourth thickness T4.

[0057] With respect to a virtual X-axis, which is directed from the outer side surface 400 towards the inner side surface 410, the outer side surface can be set at X0 (a zero point), a point at which the gas hole 142 begins can be set at X1, a point at which the gas hole 142 ends can be set at X3 and a point at which the inclined section 420 begins can be set at X2.

[0058] The length of X3 (e.g., distance between X3 and X0) can be longer than the length of X2 (e.g., distance between X2 and X0), and the length of X2 can be longer than the length of X1 (e.g., distance between X1 and X0).

[0059] Fig. 5a and Fig. 5b are partial cross-sectional views of a fuel cell according to the referenced technology. A description in comparison with Fig. 3a and Fig. 3b. Parts of the same or similar type are omitted.

[0060] Referring to Fig. 5a and Fig. 5b The gas hole 142 can be located in the no-reaction zone 330 of the second separator 312. The air or reaction gas can be released from the cathode or the anode, or it can be supplied to the cathode or the anode via the gas hole 142.

[0061] A second seal 101b can form a space corresponding to the gas hole 142 and can form a gas path 341 between the membrane electrode assembly (MEA) 115 and the second separator 312.

[0062] Gas path 341 is designed with a constant height. Condensate formed in reaction zone 320 cannot therefore be easily discharged and can stagnate, thus blocking gas path 341. Furthermore, a pressure difference between a fuel supply side and an outlet side can increase, and the efficiency of the fuel cell stack can deteriorate.

[0063] As in Fig. 3a and Fig.As shown in Figure 3b, however, the exemplary embodiments of the present invention reduce an unnecessary space which corresponds to the gas path 340 between the MEA 115 and the first separator 304, and can form the flow path extension section by increasing the height of the gas path, so that the exemplary embodiments can easily discharge the condensate which is formed by the reaction gas and the air which is released by the MEA 115.

[0064] Furthermore, the exemplary embodiments can utilize the flow path extension section, enabling the exemplary embodiments to easily remove the condensate formed by the reaction gas and air supplied to or released from the cathode and anode.

[0065] Although the invention has been described in connection with what are currently considered to be expedient, exemplary embodiments, it is to be understood that the invention is not limited to the embodiments disclosed (herein), but that the scope of the invention is defined by the attached claims.

Claims

[1] Fuel cell stack comprising: a membrane electrode arrangement (115) comprising a cathode (12) and an anode (14), which are catalyst layers and are respectively formed on a first and a second surface of an electrolyte membrane (16), a first separator (304) which is arranged on one side of the membrane electrode arrangement (115), and a second separator (312) which is arranged on the other side of the membrane electrode assembly (115), wherein a gas path (340), through which a gas is released from the cathode or the anode or a gas is supplied to the cathode or the anode, is arranged between the second separator (312) and the membrane electrode arrangement (115) and is formed in a no-reaction zone (330), and wherein the gas path (340) has a flow path extension section and a height of the flow path extension section is greater than a height of a reaction zone (320), wherein the flow path extension section is formed by deforming a shape of the membrane electrode arrangement (115). [2] Fuel cell stack according to claim 1, wherein the flow path extension section has a section whose height gradually increases from the gas path. [3] Fuel cell stack according to claim 1 or 2, wherein the flow path extension section is formed on a first side surface of the membrane electrode assembly (115), and the height of a second side surface of the membrane electrode assembly forming the flow path extension section decreases along a section of the length of the second side surface. [4] Fuel cell stack according to any one of claims 1 to 3, wherein a gas hole (142) connected to the gas path (340) is formed on the second separator (312). [5] Fuel cell stack according to any one of claims 1 to 4, further comprising: a first seal (100a) which is arranged between the membrane electrode assembly (115) and the first separator (304) in the no-reaction zone (330), and a second seal (100b) which corresponds to the first seal (100a) and which is arranged between the membrane electrode assembly (115) and the second separator (312), wherein the flow path extension section is formed using the cross-sectional shapes of the first seal (100a) and the second seal (100b) to deform the shape of the membrane electrode assembly (115). [6] Fuel cell stack according to claim 5, wherein a section which uses cross-sectional shapes of the first seal (100a) and the second seal (100b) to deform the shape of the membrane electrode assembly (115) is a secondary seal (104). [7] Fuel cell stack according to claim 5 or 6, wherein an outer side surface (400) of the first seal (100a) has a first thickness (T1), an inner side surface (410) of the first seal (100a) has a second thickness (T2) which is less than the first thickness (T1), the outer side surface (400) of the second seal (100b) has a third thickness (T3) and the inner side surface (410) of the second seal (100b) has a fourth thickness (T4) which is greater than the third thickness (T3), wherein an inclined section (420) which is located in a region between the outer side surface (400) and the inner side surface (410) changes the thicknesses of the first seal (100a) and the second seal (100b). [8] Fuel cell stack according to claim 7, wherein a sum of the first thickness (T1) and the third thickness (T3) is equal to a sum of the second thickness (T2) and the fourth thickness (T4). [9] Fuel cell stack according to any one of claims 3 to 8, wherein the gas path (304) releases fuel gas released from the anode or gas released from the cathode. [10] Fuel cell stack according to claim 7 or 8, wherein a point at which the inclined section (420) begins is located in a region of the gas hole (142) with respect to a direction directed from the outer side surface (400) towards the inner side surface (410). [11] Fuel cell stack according to any one of claims 3 to 10, wherein the flow path extension section overlaps with part of a region of the gas hole (142). [12] Fuel cell stack according to any one of claims 3 to 10, wherein the flow path extension section overlaps the entire area of ​​the gas hole (142). [13] Fuel cell stack according to any one of claims 1 to 12, wherein the second separator (312) is arranged on the surface on which the cathode (12) is arranged, from the first and the second surface and forms a channel through which air flows in the reaction zone. [14] Fuel cell stack according to any one of claims 1 to 12, wherein the second separator (312) is arranged on a surface on which the anode (14) is arranged, from the first and the second surface and forms a channel through which a fuel gas flows in the reaction zone. [15] Fuel cell stack according to any one of claims 1 to 14, wherein the flow path extension section is formed at an outlet of the gas which is released from the cathode (12) or the anode (14).

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