fuel cell system

Abstract

The present invention relates to a fuel cell system. This system is prepared for situations where antioxidants within an electrolyte membrane or electrode are lost due to the antioxidant's dissolution or migration characteristics. The system is capable of improving the chemical durability of a membrane electrode assembly by compensating for the amount of antioxidant lost within the electrolyte membrane or electrode of the fuel cell stack by supplying antioxidants to the fuel cell stack from an antioxidant supply device provided in a fuel processing system and / or an air processing system.

Description

Technical Field

[0001] The present invention relates to a fuel cell system capable of improving the chemical durability of a membrane electrode assembly by compensating for the amount of antioxidant lost in an electrolyte membrane or an electrode. Background Art

[0002] A fuel cell system typically includes: a fuel cell stack for generating electrical energy; a fuel processing system (FPS) for supplying fuel (i.e., hydrogen) to the fuel cell stack; an air processing system (APS) for supplying oxygen in the air to the fuel cell stack, such as an oxidizer required for the electrochemical reaction; and a heat and water management system for controlling the operating temperature of the fuel cell stack.

[0003] A fuel cell stack has a structure composed of multiple stacked and assembled unit cells that generate electricity through the reaction between hydrogen (H2) and oxygen (O2). Each unit cell includes a membrane electrode assembly (MEA) with a perfluorinated sulfonic acid ionomer-based electrolyte membrane; an anode, which is placed on one side of the electrolyte membrane and supplied with hydrogen (H2); a cathode, which is placed on the other side of the electrolyte membrane and supplied with air; and a gas diffusion layer (GDL), which is stacked outside the anode and cathode.

[0004] Therefore, the power generation reaction of the fuel cell stack occurs in the MEA. After the hydrogen supplied to the anode (i.e., the oxidation electrode) is separated into hydrogen protons and electrons, the hydrogen protons move to the cathode (i.e., the reduction electrode) through the electrolyte membrane, and the electrons move to the cathode through an external circuit. Oxygen molecules, hydrogen protons, and electrons meet in the cathode, generating electricity and heat, and also producing water (H2O) as a reaction byproduct.

[0005] During the power generation reaction of a fuel cell, hydrogen and oxygen in the air pass through the electrolyte membrane, easily generating hydrogen peroxide (HOOH). This hydrogen peroxide generates oxygen-containing free radicals such as hydroxyl radicals (·OH) and hydroperoxyl radicals (·OOH).

[0006] These free radicals cause chemical degradation of the electrolyte membrane by attacking the perfluorinated sulfonic acid ionomer-based electrolyte membrane, thus having an adverse effect of reducing the durability of the fuel cell.

[0007] Therefore, as a conventional technique for alleviating chemical degradation of the electrolyte membrane, a method of adding various types of antioxidants to the electrolyte membrane or the electrode has been introduced.

[0008] In conventional technology, antioxidants include primary antioxidants that function as free radical scavengers and secondary antioxidants that function as hydrogen peroxide decomposers. The primary antioxidants and secondary antioxidants can be used alone or in combination.

[0009] For example, representative primary antioxidants for perfluorinated sulfonic acid electrolyte membranes used in polymer electrolyte membrane fuel cells include cerium-based antioxidants (e.g., cerium oxide, cerium dioxide, or cerium (III) nitrate hexahydrate), terephthalic acid-based antioxidants, etc. Representative secondary antioxidants include manganese-based antioxidants, such as manganese oxide.

[0010] An electrolyte membrane to which such an antioxidant is added in large amounts has increased chemical durability, but since sulfonic acid groups contained in the electrolyte membrane reduce proton conductivity by coupling with the cationic antioxidant, performance of unit cells constituting a fuel cell may be reduced.

[0011] Furthermore, antioxidants (e.g., cerium oxide) introduced into the electrolyte membrane are ionized and dissolved during fuel cell manufacturing and operation. Because antioxidants are easily mobile in the fuel cell operating environment, antioxidants introduced directly in ion form (e.g., hydrated cerium salts) can escape to the outside of each fuel cell, reducing the durability of the electrolyte membrane over the long term.

[0012] Therefore, in consideration of the performance and durability of the fuel cell, it is preferable to appropriately use an antioxidant. Summary of the Invention

[0013] In a preferred aspect, a fuel cell system is provided that can improve the chemical durability of a membrane electrode assembly by compensating for antioxidant loss within an electrolyte membrane or electrode of a fuel cell stack. For example, antioxidant can be supplied to the fuel cell stack from an antioxidant supply device disposed in a fuel processing system and / or an air processing system to prevent antioxidant loss within the electrolyte membrane or electrode due to the solubility or migration characteristics of the antioxidant.

[0014] In one aspect, a fuel cell system is provided, comprising an antioxidant supply device and a controller, wherein the antioxidant supply device is arranged at a predetermined position of a fuel processing system (FPS) for supplying hydrogen to a fuel cell stack, at a predetermined position of an air processing system (APS) for supplying air to a fuel cell stack, or at predetermined positions of the FPS and the APS, and the controller is configured to: determine the required timing for replenishing the antioxidant and supplying it to the fuel cell stack, control the supply of the antioxidant from the antioxidant supply device arranged at a predetermined position of the FPS or the APS to the fuel cell stack, or control the supply of the antioxidant from the antioxidant supply device arranged at predetermined positions of the FPS and the APS to the fuel cell stack.

[0015] Preferably, the fuel cell system may include a first antioxidant supply device, a second antioxidant supply device and a controller, wherein the first antioxidant supply device is arranged at a predetermined position of a fuel processing system (FPS) for supplying hydrogen to the fuel cell stack, and the second antioxidant supply device is arranged in a humidifier of an air processing system (APS) for supplying air to the fuel cell stack, and the controller is configured to: determine the required timing for replenishing the antioxidant and supplying it to the fuel cell stack, control the supply of the antioxidant from the first antioxidant supply device or the second antioxidant supply device to the fuel cell stack, or control the supply of the antioxidant from the first antioxidant supply device and the second antioxidant supply device to the fuel cell stack.

[0016] The first antioxidant supply device may be provided: i) upstream or downstream of the injector on the hydrogen supply line of the FPS, ii) upstream of the injector on the hydrogen circulation line, or iii) directly coupled to the injector.

[0017] The controller may be configured to determine that further supply of the antioxidant to the fuel cell stack is required when a predetermined operating time of the fuel cell stack has expired or when a vehicle on which the fuel cell stack is mounted has reached a predetermined mileage.

[0018] Furthermore, the controller may be configured to additionally use status information indicating that the current of the fuel cell stack exceeds 0 A as a factor for determining a required timing for replenishing and supplying the antioxidant to the fuel cell stack.

[0019] In addition, the controller can be configured to additionally use temperature information indicating that the temperature of the stack coolant is approximately 60°C or higher as a factor for determining the required timing for replenishing and supplying the antioxidant to the fuel cell stack to smoothly supply the antioxidant and facilitate its migration within the membrane electrode assembly.

[0020] The first antioxidant supply device can be configured to include: a mixing chamber having a hydrogen inlet hole formed on one side thereof and a hydrogen outlet hole formed on the other side thereof; an antioxidant storage device, which is arranged below the mixing chamber; a partition wall, which is configured to separate the mixing chamber and the antioxidant storage device into independent spaces; and an antioxidant discharge pipe, which is installed on the partition wall while connecting the mixing chamber and the antioxidant storage device to each other, and is configured to discharge the antioxidant in the antioxidant storage device to the mixing chamber.

[0021] An ultrasonic transducer, a heater and a level sensor may be installed on the antioxidant storage of the first antioxidant supply device, wherein the ultrasonic transducer operates in response to a control signal from the controller to generate ultrasonic waves to vaporize the antioxidant, the heater is turned on and off by the controller to heat the antioxidant, and the level sensor is used to detect the storage level of the antioxidant and transmit the detection signal to the controller.

[0022] Preferably, an ultrasonic transducer may be mounted on the antioxidant storage, and the ultrasonic transducer operates to generate ultrasonic waves to vaporize the antioxidant in response to a control signal from the controller.

[0023] The discharge pipe may be in a nozzle shape that is inclined from the hydrogen inflow hole toward the hydrogen outflow hole and has a diameter that gradually narrows toward the mixing chamber.

[0024] Preferably, the angle θ between the discharge pipe and the partition wall may be set to 0°<θ<90°, and the lower inner diameter of the discharge pipe located in the antioxidant storage may be set larger than the upper inner diameter of the discharge pipe located in the mixing chamber.

[0025] Preferably, a heater is installed on the antioxidant storage, and the on and off of the heater is controlled by the controller to heat the stored antioxidant. Before the antioxidant is supplied to the mixing chamber, the heater operates in response to a control signal from the controller to increase the temperature of the antioxidant solution to about 60 to 80°C.

[0026] Preferably, a level sensor may be installed on the antioxidant storage, and the level sensor is used to detect the storage level of the antioxidant and transmit a detection signal to the controller.

[0027] Preferably, the controller may be configured to determine a filling timing of the antioxidant based on a detection signal of the level sensor, and display a warning for filling the antioxidant on an interior display of the fuel cell vehicle.

[0028] The first antioxidant supply device may include an antioxidant storage in which the antioxidant is stored; a discharge pipe coupled to a bottom of the antioxidant storage; and a valve installed on the discharge pipe and configured to open and close in response to a control signal from a controller.

[0029] A heater and a level sensor may be installed on the antioxidant storage of the first antioxidant supply device. The heater is turned on and off by the controller to heat the stored antioxidant. The level sensor is used to detect the storage level of the antioxidant and transmit a detection signal to the controller.

[0030] Preferably, a heater may be installed on the antioxidant reservoir, the on / off switching of which is controlled by a controller to heat the stored antioxidant. Before the antioxidant is supplied to the fuel cell stack, the heater operates in response to a control signal from the controller to raise the temperature of the antioxidant solution to approximately 60 to 80°C.

[0031] Preferably, a level sensor may be installed on the antioxidant storage, and the level sensor is used to detect the storage level of the antioxidant and transmit a detection signal to the controller.

[0032] Preferably, the controller may be configured to determine a filling timing of the antioxidant based on a detection signal of the level sensor, and display a warning for filling the antioxidant on an interior display of the fuel cell vehicle.

[0033] A second antioxidant supply device, which is provided at a predetermined position of the APS, among the antioxidant supply devices may be provided within the humidifier.

[0034] The second antioxidant supply device may include: an antioxidant reservoir disposed below a partition wall formed within the humidifier; a hollow fiber membrane disposed within the antioxidant reservoir and configured to allow the antioxidant to permeate the hollow fiber membrane through which dry air passes; and a level sensor mounted on the antioxidant reservoir and configured to detect a storage level of the antioxidant and transmit a detection signal to a controller. In addition to the first dry air inlet for introducing dry air into the humidifier, a second dry air inlet for introducing dry air into the antioxidant reservoir is formed on one side of the humidifier.

[0035] In particular, a valve for air distribution may be provided at the rear ends of the first dry air inlet and the second dry air inlet, the valve being opened and closed to supply dry air to the humidifier through the first dry air inlet, or to supply dry air to the humidifier and the second antioxidant supply device at the same time.

[0036] Preferably, a level sensor may be installed on the antioxidant storage, and the level sensor is used to detect the storage level of the antioxidant and transmit a detection signal to the controller.

[0037] The controller may be configured to determine a filling timing of the antioxidant based on a detection signal of the level sensor, and display a warning for filling the antioxidant on an interior display of the fuel cell vehicle.

[0038] The controller can be configured to: additionally use status information indicating i) the current of the fuel cell stack exceeds 0 A as a factor for determining when further antioxidant needs to be supplied to the fuel cell stack; and / or use status information indicating ii) the temperature of the stack coolant is 60°C or higher as a factor for determining when further antioxidant needs to be supplied to the fuel cell stack, so as to smoothly supply the antioxidant and allow the antioxidant to migrate within the membrane electrode assembly.

[0039] Other aspects of the invention are disclosed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The above and other features of the present invention will now be described in detail with reference to certain exemplary embodiments shown in the accompanying drawings, which are hereinafter provided for illustration only and are therefore non-limiting to the present invention, in which:

[0041] Figure 1 An exemplary fuel cell system according to an exemplary embodiment of the present invention is shown.

[0042] Figure 2 A first antioxidant supply device that is a component of an exemplary fuel cell system according to an exemplary embodiment of the present invention is shown.

[0043] Figure 3 The locations shown are: Figure 2 The first antioxidant supply is shown disposed in a fuel processing system (FPS).

[0044] Figure 4 The status shown is: Figure 2 The first antioxidant supply device shown is arranged on Figure 3 At position B shown.

[0045] Figure 5 A first antioxidant supply device according to an exemplary embodiment of the present invention is shown among components of a fuel cell system.

[0046] Figure 6 The locations shown are: Figure 5 The first antioxidant supply device is shown to be provided in the FPS.

[0047] Figure 7 The status shown is: Figure 5 The first antioxidant supply device shown is arranged on Figure 6 At position G shown.

[0048] Figure 8 The illustrated external perspective view shows a state in which the second antioxidant supply device, which is a component of the fuel cell system according to the exemplary embodiment of the present invention, is provided in the humidifier.

[0049] Figure 9 A state is shown in which the second antioxidant supply device, which is a component of the fuel cell system according to the exemplary embodiment of the present invention, is provided in the humidifier.

[0050] It should be understood that the accompanying drawings are not necessarily drawn to scale, and that they show various preferred features that illustrate the basic principles of the invention in a somewhat simplified manner. The specific design features of the present invention disclosed herein (including, for example, specific dimensions, orientations, locations, and shapes) will be determined in part by the specific target application and use environment.

[0051] In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. DETAILED DESCRIPTION

[0052] Hereinafter, preferred exemplary embodiments of the present invention will be described with reference to the accompanying drawings. Matters shown in the drawings may differ from actual implementation forms because the schematic drawings are only used to easily describe exemplary embodiments of the present invention.

[0053] It should be understood that the term "vehicle" or "vehicular" or other similar terms used herein generally includes motor vehicles, such as passenger vehicles including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, watercraft including various boats and ships, aircraft, etc., and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from non-petroleum energy sources). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, such as a vehicle that has both gasoline-powered and electric-powered power.

[0054] Unless otherwise indicated, all numbers, values and / or expressions relating to ingredient amounts, reaction conditions, polymer compositions and formulations used herein are to be understood as modified in all instances by the term "about" since such numbers are approximations that particularly reflect the inherent uncertainties of measurement encountered in obtaining such values.

[0055] Further, unless otherwise stated or apparent from the context, the term "about" as used herein is understood to mean within the normal tolerance range in the art, for example, within two standard deviations of the mean. "About" can be understood to mean within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless the context clearly indicates otherwise, all numerical values provided herein are modified by the term "about."

[0056] In this specification, when describing a range of a variable, it will be understood that the variable includes all values, including the endpoints described in the range. For example, the range "5 to 10" will be understood to include any subranges (e.g., 6 to 10, 7 to 10, 6 to 9, 7 to 9, etc.) and individual values of 5, 6, 7, 8, 9, and 10, and will also be understood to include any values between the valid integers in the range, such as 5.5, 6.5, 7.5, 5.5 to 8.5, 6.5 to 9, etc. In addition, for example, the range "10% to 30%" will be understood to include subranges (e.g., 10% to 15%, 12% to 18%, 20% to 30%, etc.) and all integers (including values of 10%, 11%, 12%, 13%, etc. up to 30%), and will also be understood to include any values between the valid integers in the range, such as 10.5%, 15.5%, 25.5%, etc.

[0057] If there is a loss of antioxidant in the electrolyte membrane and the ionomers of the anode and cathode of the fuel cell stack, the fuel cell system may supply antioxidant to the fuel cell stack from the outside to compensate for the amount of the lost antioxidant.

[0058] Figure 1 An exemplary fuel cell system according to an exemplary embodiment of the present invention is shown. Reference numeral 100 denotes a fuel cell stack.

[0059] A fuel processing system (FPS) 200 for supplying hydrogen and an air processing system (APS) 300 for supplying oxygen in the air are coupled to the fuel cell stack 100 .

[0060] When supplying the antioxidant to the fuel cell stack 100 , the fuel cell system may be configured to supply the antioxidant through the FPS 200 or the APS 300 , or both the FPS 200 and the APS 300 .

[0061] As in Figure 1 As shown in the figure, the FPS 200 may include: a hydrogen supply line 201, which is connected from a hydrogen tank to the fuel cell stack 100; a hydrogen circulation line 202, which is used to circulate unreacted hydrogen in the fuel cell stack 100 to the hydrogen supply line 201; an ejector 210, which is arranged at the point where the hydrogen supply line 201 and the hydrogen circulation line 202 meet; and a water collector 220, which is used to collect water discharged together with the unreacted hydrogen in the fuel cell stack 100.

[0062] The injector 210 is used to supply new hydrogen, which flows from a hydrogen tank along the hydrogen supply line 201 , and unreacted circulating hydrogen via the hydrogen circulation line 202 toward the anode of the fuel cell stack 100 .

[0063] In particular, the first antioxidant supplying device 110 according to an embodiment of the present invention is provided at a given position of the FPS 200 .

[0064] For example, as in Figure 3 As shown in FIG, the first antioxidant supplier 110 may be provided at one of the positions upstream A or downstream B of the injector 210 on the hydrogen supply line 201 and upstream C of the injector 210 on the hydrogen circulation line 202 .

[0065] As in Figure 2 As shown in the figure, the first antioxidant supply device 110 can be configured to include a mixing chamber 111, an antioxidant storage 114, a partition wall 113, an antioxidant discharge pipe 112, etc., the mixing chamber 111 is formed with a hydrogen inlet hole 111-1 on one side and a hydrogen outlet hole 111-2 on the other side, the antioxidant storage 114 is arranged below the mixing chamber 111, the partition wall 113 separates the mixing chamber 111 and the antioxidant storage 114 into independent spaces, and the antioxidant discharge pipe 112 is configured to make the mixing chamber 111 and the antioxidant storage 114 communicate with each other and is installed on the partition wall 113.

[0066] The antioxidant discharge pipe 112 may serve as a passage for smoothly supplying the antioxidant in the antioxidant storage 114 to the mixing chamber 111. The partition wall 113 may serve to prevent the antioxidant supplied from the antioxidant storage 114 to the mixing chamber 111 from flowing back to the antioxidant storage 114.

[0067] In addition, an ultrasonic transducer 117 that operates in response to a signal from the controller 400 may be provided in the antioxidant storage 114. The ultrasonic transducer 117 may be used to vaporize the antioxidant solution by generating ultrasonic waves.

[0068] The hydrogen inflow hole 111 - 1 of the mixing chamber 111 may be coupled to a hydrogen tank, such as a hydrogen supply source, and the hydrogen outflow hole 111 - 2 may be coupled to the fuel cell stack 100 so that hydrogen flows from the hydrogen inflow hole 111 - 1 of the mixing chamber 111 to the hydrogen outflow hole 111 - 2 thereof.

[0069] The hydrogen flowing from the hydrogen inflow hole 111-1 of the mixing chamber 111 to the hydrogen outflow hole 111-2 thereof can be used as a driving fluid to absorb the antioxidant in the antioxidant reservoir 114 (for example, the antioxidant vaporized by the ultrasonic waves generated by the ultrasonic transducer 117), just as hydrogen absorbs the antioxidant in a vacuum. Therefore, the vaporized antioxidant in the antioxidant reservoir 114 can be easily supplied to the mixing chamber 111 through the discharge pipe 112.

[0070] The discharge pipe 112 can have a nozzle shape, which is inclined from the hydrogen inlet hole 111-1 toward the hydrogen outlet hole 111-2 and has a diameter that gradually narrows toward the mixing chamber 111, so that the antioxidant in the antioxidant storage 114 (for example, the antioxidant vaporized by the ultrasonic wave generated by the ultrasonic transducer 117) can be more easily supplied to the mixing chamber 111 through the discharge pipe 112.

[0071] For this reason, as in Figure 2 As shown in FIG, the angle θ between the discharge pipe 112 and the partition wall 113 can be set to 0°<θ<90°. The inner diameter D of the lower portion of the discharge pipe 112 located in the antioxidant storage 114 is in The inner diameter D of the upper portion of the discharge pipe 112 located in the mixing chamber 111 may be set to be greater than out big.

[0072] The bottom of the discharge pipe 112 may be configured to match the ultrasonic transducer 117 up and down, so that the antioxidant vaporized by the ultrasonic waves generated by the ultrasonic transducer 117 directly enters the discharge pipe 112 .

[0073] In addition, the opening and closing are controlled by the controller (in Figure 1 A heater 115a controlled by a control unit (denoted by 400 in FIG. 1 ) may be installed on the antioxidant storage 114 to heat the antioxidant stored in the antioxidant storage 114.

[0074] The heater 115 a may be used to prevent the antioxidant solution in the antioxidant storage 114 from freezing when the external environment is below zero, and may also be used to perform heating to smoothly vaporize the antioxidant.

[0075] Before the antioxidant in the antioxidant storage 114 is supplied to the mixing chamber 111, the heater 115a may be operated by a control signal from the controller 400 so that the temperature of the antioxidant solution may be increased to a temperature of about 60 to 80° C. This is because, when the temperature of the antioxidant solution is less than about 60° C., the antioxidant solution is hardly vaporized by the ultrasonic waves generated by the ultrasonic transducer 117, and when the temperature of the antioxidant solution is greater than about 80° C., the antioxidant solution is excessively vaporized by the ultrasonic waves generated by the ultrasonic transducer 117.

[0076] In addition, a level sensor 116 a is installed on the antioxidant storage 114 , and the level sensor 116 a is used to detect the storage level of the antioxidant and transmit a detection signal to the controller 400 .

[0077] Therefore, when the antioxidant stored in the antioxidant storage 114 is continuously consumed and is less than a given level, the level sensor 116a may transmit a level detection signal to the controller 400. In response, the controller 400 may cause the filling of the antioxidant by displaying a warning message for filling the antioxidant on the interior display of the fuel cell vehicle.

[0078] Since the user can monitor the remaining amount of the antioxidant through the display responsive to the level detection signal of the level sensor 116 a , the user can recognize the filling timing of the antioxidant without missing the filling timing.

[0079] As in Figure 3 As shown in FIG, the first antioxidant supplier 110 may be provided at one of the positions upstream A or downstream B of the injector 210 on the hydrogen supply line 201 and upstream C of the injector 210 on the hydrogen circulation line 202 .

[0080] The operation of the first antioxidant supplying device 110 will be described below.

[0081] Figure 4 The schematic cross-sectional view shown is as follows: Figure 2 The first antioxidant supply device 110 is provided at Figure 3 Position B (between the injector 210 and the fuel cell stack 100) is shown.

[0082] As in Figure 4 As shown in FIG, when the injector 210 supplies new hydrogen and / or recycled hydrogen from the hydrogen tank to the mixing chamber 111, hydrogen may enter the mixing chamber 111 through the hydrogen inflow hole 111-1 and may be supplied to the fuel cell stack 100 through the hydrogen outflow hole 111-2.

[0083] In this case, the antioxidant may be supplied from the first antioxidant supplier 110 to the fuel cell stack 100 in response to a command signal from the controller 400 at a desired timing when the antioxidant needs to be replenished and supplied to the fuel cell stack 100 .

[0084] The required timing for replenishing the antioxidant and supplying it to the fuel cell stack 100 may vary depending on the operating mode of the fuel cell stack 100. The required timing may be set to the timing when the fuel cell stack has been operating for a given time after the fuel cell system is initially manufactured (e.g., after tens of thousands of hours of operation) or the timing when the mileage of a vehicle equipped with the fuel cell stack reaches a given mileage (e.g., tens of thousands of kilometers).

[0085] Therefore, when the controller 400 determines the required timing for replenishing the antioxidant and supplying it to the fuel cell stack 100 based on the cumulative operating time of the fuel cell stack or the cumulative mileage of the vehicle, the controller 400 applies a current signal for operation to the heater 115a and the ultrasonic transducer 117 of the first antioxidant supply device 110.

[0086] Next, the temperature of the antioxidant solution in the antioxidant storage 114 can be increased to about 60 to 80° C., at which the antioxidant solution can be properly vaporized by the operation of the heater 115 a. The antioxidant solution can be easily vaporized by the ultrasonic wave generated by the ultrasonic transducer 117.

[0087] Therefore, after the antioxidant vaporized in the antioxidant storage 114 enters the mixing chamber 111 through the exhaust pipe 112 , the antioxidant may be mixed with hydrogen and supplied to the fuel cell stack 100 .

[0088] It is best to supply the antioxidant in a section of the fuel cell stack 100 where the current is greater than 0 A. This is because the antioxidant can be easily supplied to each unit cell of the fuel cell stack using sufficient fluid flow, such as hydrogen from the FPS (operated to generate current for the fuel cell stack) and oxygen from the APS.

[0089] Therefore, as an element required for the controller 400 to determine the required timing at which the antioxidant needs to be replenished and supplied to the fuel cell stack 100 , state information indicating that the current of the fuel cell stack 100 is greater than 0 A may be additionally used.

[0090] Alternatively, as an element required for the controller 400 to determine the desired timing for replenishing the antioxidant and supplying it to the fuel cell stack 100, temperature information indicating that the temperature of the stack coolant is approximately 60°C or higher may be additionally used to smoothly supply the antioxidant and facilitate its migration within the membrane electrode assembly.

[0091] Therefore, after the fuel cell system is started, when the temperature of the stack coolant becomes 60° C. or higher, the antioxidant can be supplied to the fuel cell stack in response to an instruction from the controller 400. In this case, the reason for limiting the temperature of the stack coolant to 60° C. or higher is that when the temperature of the stack coolant is similar to the temperature of the antioxidant supplied to the fuel cell stack (e.g., raised to a temperature of 60 to 80° C. by the heater as described above), the antioxidant can be easily supplied to the electrodes and the electrolyte membrane as much as possible without being in a condensed state.

[0092] As described above, since the antioxidant is replenished and supplied to the fuel cell stack 100 using the first antioxidant supply device 110 according to an embodiment of the present invention, the amount of antioxidant lost in the electrolyte membrane ionomer or electrode layer constituting the fuel cell stack can be compensated. Therefore, the chemical durability of the membrane electrode assembly can be improved.

[0093] The first antioxidant supplier 110 may be provided at a given position of the FPS 200 .

[0094] For example, as in Figure 6 As shown in FIG, the first antioxidant supply device 110 may be provided at one of upstream D or downstream E of the injector 210 on the hydrogen supply line 201 , upstream F of the injector 210 on the hydrogen circulation line 202 , and a position directly coupled to the injector 210 .

[0095] As in Figure 5 As shown in , the first antioxidant supply device 110 can be configured to include: an antioxidant storage 114 in which antioxidant is stored; a discharge pipe 118 connected to the bottom of the antioxidant storage 114; and a valve 119, which is installed on the discharge pipe 118 and is opened and closed by a control signal from a controller.

[0096] In addition, a heater 115 b may be installed on the antioxidant storage 114 , and the on and off of the heater 115 b is controlled by the controller.

[0097] The heater 115b may be used to prevent the antioxidant solution within the antioxidant reservoir 114 from freezing and prevent additional condensation or excessive energy loss by heating the antioxidant to a temperature similar to the operating temperature of the fuel cell system.

[0098] To this end, before the antioxidant in the antioxidant storage 114 is supplied to the fuel cell stack, the heater 115b may be operated in response to a control signal from the controller 400 so that the temperature of the antioxidant solution is increased to about 60 to 80°C.

[0099] In addition, a level sensor 116 b may be installed on the antioxidant storage 114 , and the level sensor 116 b is used to detect the storage level of the antioxidant and transmit a detection signal to the controller 400 .

[0100] Therefore, when the antioxidant stored in the antioxidant storage 114 is continuously consumed and is less than a given level, the level sensor 116b may transmit a level detection signal to the controller 400. In response, the controller 400 may cause the filling of the antioxidant by displaying a warning message for filling the antioxidant on the interior display of the fuel cell vehicle.

[0101] As in Figure 6 As shown in FIG, the first antioxidant supplier 110 may be provided at one of the positions upstream D or downstream E of the injector 210 on the hydrogen supply line 201 and upstream F of the injector 210 on the hydrogen circulation line 202 .

[0102] The operation of the first antioxidant supplying device 110 will be described below.

[0103] Figure 7 The status shown is: Figure 5 The first antioxidant supply device 110 is provided at Figure 6 Position G is shown (ie, the position directly coupled to the injector 210).

[0104] As in Figure 7 As shown in FIG, among the components of the first antioxidant supply device 110 , the discharge pipe 118 coupled to the bottom of the antioxidant storage 114 may be coupled to the injector 210 in such a manner as to communicate with the injector 210 .

[0105] The injector 210 may supply new hydrogen and / or recycled hydrogen from a hydrogen tank to the fuel cell stack 100 .

[0106] In this case, the antioxidant may be supplied from the first antioxidant supplier 110 to the fuel cell stack 100 in response to a command signal from the controller 400 at a desired timing when the antioxidant needs to be replenished and supplied to the fuel cell stack 100 .

[0107] As described above, the required timing at which the antioxidant needs to be replenished and supplied to the fuel cell stack 100 may be different depending on the operating mode of the fuel cell stack 100. The required timing may be set to the timing when the fuel cell stack has been operated for a given time after the fuel cell system is initially manufactured (e.g., after tens of thousands of hours of operation) or the timing when the mileage of a vehicle equipped with the fuel cell stack reaches a given mileage (e.g., tens of thousands of kilometers).

[0108] Therefore, when the controller 400 determines the required timing for replenishing the antioxidant and supplying it to the fuel cell stack 100 based on the cumulative operating time of the fuel cell stack or the cumulative mileage of the vehicle, the controller 400 can apply a current signal to operate the heater 115b (according to another embodiment, the heater 115b is included in the first antioxidant supply device 110) and can also apply a control signal for opening to the valve 119.

[0109] Next, after the temperature of the antioxidant solution in the antioxidant storage 114 is increased to about 60 to 80° C. by the operation of the heater 115 b , the antioxidant enters the injector 210 by the opening operation of the valve 119 .

[0110] Therefore, after the antioxidant in the antioxidant storage 114 enters the injector 210 through the valve 119 , the antioxidant may be mixed with hydrogen and supplied to the fuel cell stack 100 .

[0111] It is best to supply the antioxidant in a section of the fuel cell stack 100 where the current is greater than 0 A. The reason for this is that the antioxidant can be easily supplied to each unit cell of the fuel cell stack using sufficient fluid flow, such as hydrogen from the FPS (operated to generate current for the fuel cell stack) and oxygen from the air handling system.

[0112] Therefore, as an element required for the controller 400 to determine the required timing at which the antioxidant needs to be replenished and supplied to the fuel cell stack 100 , state information indicating that the current of the fuel cell stack 100 is greater than 0 A may be additionally used.

[0113] Alternatively, as an element required for the controller 400 to determine the desired timing for replenishing the antioxidant and supplying it to the fuel cell stack 100, temperature information indicating that the temperature of the stack coolant is approximately 60°C or higher may be additionally used to smoothly supply the antioxidant and facilitate its migration within the membrane electrode assembly.

[0114] Therefore, after the fuel cell system is started, when the temperature of the stack coolant becomes approximately 60° C. or higher, the antioxidant may be supplied to the fuel cell stack in response to an instruction from the controller 400. As described above, the reason for limiting the temperature of the stack coolant to approximately 60° C. or higher is that when the temperature of the stack coolant is similar to the temperature of the antioxidant supplied to the fuel cell stack (e.g., raised to a temperature of 60 to 80° C. by the heater as described above), the antioxidant can be easily supplied to the electrodes and the electrolyte membrane as much as possible without condensing.

[0115] As described above, since the first antioxidant supply device 110 is used to replenish the antioxidant and supply it to the fuel cell stack 100, the amount of antioxidant lost in the electrolyte membrane ionomer or electrode layer constituting the fuel cell stack can be compensated. Therefore, the chemical durability of the membrane electrode assembly can be improved.

[0116] The second antioxidant supply device 120 provided in the air processing system (APS) 300 of the fuel cell system will be described below.

[0117] As in Figure 1As shown in , the APS 300 can be configured to include a filter 301, a compressor 302, a humidifier 320, etc., wherein the filter 301 is used to filter external air, the compressor 302 is used to compress and supply external air, and the humidifier 320 is used to humidify the compressed dry air and supply the humidified air to the fuel cell stack 100.

[0118] In particular, the second antioxidant supplier 120 may be independently mounted on the humidifier 320 among components of the APS 300 , or integrated with the humidifier 320 .

[0119] Figure 8 and Figure 9 The illustrated state is that the second antioxidant supply device 120, which is a component of the fuel cell system, is provided in the humidifier 320. Reference numeral 320 denotes the humidifier.

[0120] A humidified air inlet 321 extending from the fuel cell stack is formed on the upper side of the humidifier 320. A first dry air inlet 322 for introducing dry air may be formed on one side of the humidifier 320. A humidified air supply hole 323 is formed on the other side of the humidifier 320, through which humidified air is directed to the fuel cell stack. A humidified air outlet 324 is formed at the bottom of the humidifier 320, through which the remaining humidified air is discharged to the outside.

[0121] In this case, a bundle of hollow fiber membranes 325 a may be provided in the humidifier 320 so that dry air from the compressor can be humidified through the hollow fiber membranes 325 a.

[0122] In particular, the second antioxidant supply device 120 may be installed at the bottom of the humidifier 320 .

[0123] As in Figure 8 and Figure 9 As shown in , the second antioxidant supply device 120 can be configured to include: an antioxidant storage 122, which is arranged at the bottom of the humidifier 320, and the humidifier 320 has a partition wall 121 inserted between the antioxidant storage 122 and the mixing chamber; and a level sensor 123, which is used to detect the antioxidant level in the antioxidant storage 122.

[0124] In this case, a bundle of hollow fiber membranes 325 b may be provided in the antioxidant storage 122 so that dry air from the compressor carries the antioxidant while passing through the hollow fiber membranes 325 b.

[0125] Elements made of polyethersulfone (PES) or polyetherimide (PEI) may be used as the hollow fiber membranes 325a, 325b.

[0126] In addition to the first dry air inlet 322 for introducing dry air, a second dry air inlet 124 may be formed at one side of the humidifier 320 , through which the dry air is guided to the antioxidant storage 122 .

[0127] A valve 125 for air distribution may be provided at the rear end of the first dry air inlet 322 and the second dry air inlet 124, and the valve 125 is opened and closed to supply the dry air from the compressor 302 to the humidifier 320 through the first dry air inlet 322, or to supply the dry air from the compressor 302 to the humidifier 320 and the second antioxidant supply device 120 at the same time.

[0128] The following describes the operation of the second antioxidant supply device provided in the APS of the fuel cell system.

[0129] In a normal operating state of the fuel cell system, after external air (eg, dry air) compressed by the compressor 302 is supplied to the humidifier 320 through the first dry air inlet 322 , the dry air may flow along the inside of the hollow fiber membrane 325 a .

[0130] At the same time, the humid air exhausted from the fuel cell stack can penetrate into the interior of the hollow fiber membrane 325a, so the dry air flowing along the interior of the hollow fiber membrane 325a can be humidified. The humidified air can be exhausted from the hollow fiber membrane 325a and supplied to the cathode of the fuel cell stack.

[0131] In this case, the antioxidant may be supplied from the second antioxidant supplier 120 to the fuel cell stack 100 in response to a command signal from the controller 400 at a desired timing when the antioxidant needs to be replenished and supplied to the fuel cell stack 100 .

[0132] As described above, the required timing for replenishing the antioxidant and supplying it to the fuel cell stack 100 may be different depending on the operating mode of the fuel cell stack, but can be set to a timing when the fuel cell stack has been operating for tens of thousands of hours after the fuel cell system is initially manufactured or a timing when the mileage of a vehicle equipped with the fuel cell stack reaches tens of thousands of kilometers.

[0133] Therefore, when the controller 400 determines the required timing to replenish and supply antioxidant to the fuel cell stack 100 based on the cumulative operating time of the fuel cell stack or the cumulative mileage of the vehicle, the controller 400 may apply a control signal for opening to the valve 125 for air distribution.

[0134] Therefore, the dry air from the compressor 302 may be supplied to the humidifier 320 through the first dry air inlet 322 , and may be simultaneously supplied to the antioxidant storage 122 of the second antioxidant supply device 120 through the second dry air inlet 124 .

[0135] When the dry air supplied to the antioxidant storage 122 flows along the inside of the hollow fiber membrane 325b, the antioxidant stored in the antioxidant storage 122 may penetrate into the hollow fiber membrane 325b, and thus may be humidified to allow the dry air to entrain the antioxidant.

[0136] Therefore, the air containing the antioxidant, which is in a state where dry air has been humidified along with the antioxidant within the hollow fiber membrane 325b, can be discharged from the hollow fiber membrane 325a and can be supplied to the fuel cell stack.

[0137] As described above, since the second antioxidant supply device 120 is used to replenish the antioxidant and supply it to the fuel cell stack 100, the amount of antioxidant lost in the electrolyte membrane ionomer or electrode layer constituting the fuel cell stack can be compensated. Therefore, the chemical durability of the membrane electrode assembly can be improved.

[0138] In addition, antioxidant may be supplied to the fuel cell stack using only the first antioxidant supply device 110 provided in the FPS 200, antioxidant may be supplied to the fuel cell stack using only the second antioxidant supply device 120 provided in the APS 300, or antioxidant may be supplied to the fuel cell stack using both the first antioxidant supply device 110 and the second antioxidant supply device 120.

[0139] The antioxidants that can be used in the embodiments of the present invention may include those having a metal oxide (such as cerium oxide or manganese oxide), cerium (III) nitrate hexahydrate, cerium sulfate, terephthalate-based antioxidants, or perovskite structure. One or two or more antioxidants can be used.

[0140] In addition, a primary antioxidant (e.g., a cerium-based antioxidant (e.g., cerium oxide, cerium dioxide, or cerium (III) nitrate hexahydrate) or a terephthalic acid-based antioxidant) and a secondary antioxidant (e.g., manganese oxide) can be used as antioxidants that can be used in various exemplary embodiments of the present invention. Alternatively, the primary antioxidant and the secondary antioxidant can be used together. Considering the mobility of the antioxidant within the electrolyte membrane, cerium (III) nitrate hexahydrate can be preferably used.

[0141] The present invention provides the following benefits through a solution. To address the potential loss of antioxidants within the electrolyte membrane or electrodes of a fuel cell stack during fuel cell stack production due to the antioxidant's solubility or migration characteristics, antioxidants can be supplied to the fuel cell stack at the right time using an independent antioxidant supply device provided in the FPS and / or APS. This improves the chemical durability of the membrane electrode assembly by compensating for antioxidant losses within the electrolyte membrane or electrodes.

[0142] Although the exemplary embodiments of the present invention have been disclosed for illustrative purposes, it will be understood by those skilled in the art that various modifications, additions and substitutions may be made without departing from the scope and spirit of the present invention as defined by the appended claims. Therefore, the true technical scope of the present invention should be defined by the appended claims.

[0143] Although the exemplary embodiments of the present invention have been described in detail above, the terms and words used in this specification and claims should not be interpreted as limited to the conventional meaning or dictionary meaning. In addition, the exemplary embodiments described in this specification and the configuration shown in the accompanying drawings are merely a preferred exemplary embodiment of the present invention. Therefore, the scope of the present invention is not limited to the above exemplary embodiments. Various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the appended claims are also included in the scope of the present invention.

Claims

1. A fuel cell system comprising: an antioxidant supply device provided at a predetermined position of a fuel processing system FPS for supplying hydrogen to the fuel cell stack, at a predetermined position of an air processing system APS for supplying air to the fuel cell stack, or at predetermined positions of the FPS and the APS; A controller configured to: when it is necessary to further supply antioxidant to the fuel cell stack, at a predetermined discontinuous required timing, control the supply of antioxidant from an antioxidant supply device set at a predetermined position of the FPS or APS to the fuel cell stack, or control the supply of antioxidant from an antioxidant supply device set at predetermined positions of the FPS and APS to the fuel cell stack.

2. The fuel cell system according to claim 1, wherein: The first antioxidant supplier disposed at a predetermined position of the FPS is disposed upstream or downstream of an injector on a hydrogen supply line of the FPS, upstream of an injector on a hydrogen circulation line, or directly connected to an injector.

3. The fuel cell system according to claim 1, wherein: The controller is configured to determine that further supply of antioxidant to the fuel cell stack is required when a predetermined operating time of the fuel cell stack has expired or when a vehicle equipped with the fuel cell stack has reached a predetermined mileage.

4. The fuel cell system according to claim 2, wherein: The first antioxidant supply device comprises: a mixing chamber having a hydrogen inflow hole formed on one side thereof and a hydrogen outflow hole formed on the other side thereof; an antioxidant storage disposed below the mixing chamber; a partition wall configured to separate the mixing chamber and the antioxidant storage into independent spaces; An antioxidant discharge pipe is installed on the partition wall while communicating the mixing chamber and the antioxidant storage with each other, and is configured to discharge the antioxidant in the antioxidant storage to the mixing chamber.

5. The fuel cell system according to claim 4, wherein: An ultrasonic transducer is mounted on the antioxidant storage, and operates to generate ultrasonic waves to vaporize the antioxidant in response to a control signal from the controller.

6. The fuel cell system according to claim 4, wherein: The antioxidant discharge pipe has a nozzle shape that is inclined from the hydrogen inflow hole toward the hydrogen outflow hole and has a diameter that gradually narrows toward the mixing chamber.

7. The fuel cell system according to claim 4, wherein: The angle θ between the antioxidant discharge pipe and the partition wall is set to 0°<θ<90°, An inner diameter of a lower portion of the discharge pipe located within the antioxidant storage is set to be larger than an inner diameter of an upper portion of the discharge pipe located within the mixing chamber.

8. The fuel cell system according to claim 4, wherein: A heater is installed on the antioxidant storage, and the on and off of the heater is controlled by the controller to heat the antioxidant.

9. The fuel cell system according to claim 8, wherein: Before supplying the antioxidant to the mixing chamber, the heater is operated to increase the temperature of the antioxidant solution to 60 to 80° C. in response to a control signal from the controller.

10. The fuel cell system according to claim 4, wherein: A level sensor is installed on the antioxidant storage, and is used to detect a storage level of the antioxidant and transmit a detection signal to the controller.

11. The fuel cell system according to claim 10, wherein: The controller is configured to determine a filling timing of the antioxidant based on a detection signal of the level sensor, and display a warning for filling the antioxidant on an interior display of the fuel cell vehicle.

12. The fuel cell system according to claim 2, wherein: The first antioxidant supply device comprises: an antioxidant reservoir storing an antioxidant; a discharge pipe connected to the bottom of the antioxidant storage; A valve is mounted on the discharge pipe and is configured to open and close in response to a control signal from the controller.

13. The fuel cell system according to claim 12, wherein: A heater is installed on the antioxidant storage, and the controller controls the on and off of the heater to heat the stored antioxidant.

14. The fuel cell system according to claim 13, wherein: Before supplying the antioxidant to the fuel cell stack, the heater operates to increase the temperature of the antioxidant solution to 60 to 80° C. in response to a control signal from the controller.

15. The fuel cell system according to claim 13, wherein: A level sensor is installed on the antioxidant storage, and is used to detect a storage level of the antioxidant and transmit a detection signal to the controller.

16. The fuel cell system according to claim 15, wherein: The controller is configured to determine a filling timing of the antioxidant based on a detection signal of the level sensor, and display a warning for filling the antioxidant on an interior display of the fuel cell vehicle.

17. The fuel cell system according to claim 1, wherein: The second antioxidant supply device provided at a predetermined position of the APS in the antioxidant supply device is provided in the humidifier. Wherein, the second antioxidant supply device comprises: an antioxidant reservoir disposed at the bottom of the humidifier, wherein the humidifier has a partition wall interposed between the antioxidant reservoir and a mixing chamber; a hollow fiber membrane disposed in the antioxidant storage and arranged so that the antioxidant permeates into the hollow fiber membrane through which the dry air passes, In addition to the first dry air inlet for introducing dry air into the humidifier, a second dry air inlet for introducing dry air into the antioxidant storage is formed on one side of the humidifier.

18. The fuel cell system according to claim 17, wherein: Valves for air distribution are provided at rear ends of the first dry air inlet and the second dry air inlet, the valves being opened and closed to supply dry air to the humidifier through the first dry air inlet, or to supply dry air to the humidifier and the second antioxidant supply device simultaneously; And / or a level sensor is installed on the antioxidant storage, and the level sensor is used to detect the storage level of the antioxidant and transmit a detection signal to the controller.

19. The fuel cell system according to claim 18, wherein: The controller is configured to determine a filling timing of the antioxidant based on a detection signal of the level sensor, and display a warning for filling the antioxidant on an interior display of the fuel cell vehicle.

20. The fuel cell system according to claim 1, wherein: The controller is configured to: additionally use status information indicating i) the current of the fuel cell stack exceeds 0 A as a factor for determining when further antioxidant needs to be supplied to the fuel cell stack; and / or use status information indicating ii) the temperature of the stack coolant is 60°C or higher as a factor for determining when further antioxidant needs to be supplied to the fuel cell stack, so as to supply antioxidant and allow the antioxidant to migrate within the membrane electrode assembly.

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