A rapid activation method for high-temperature methanol fuel cells

Abstract

The present application discloses a method for rapid activation of a high-temperature methanol fuel cell, and belongs to the field of fuel cell technology. The method is to activate the fuel cell by electrochemical reduction treatment and gas pressure pulse treatment. Based on the internal characteristics of the high-temperature fuel cell, the present application introduces an electrochemical reduction operation to achieve in-situ removal of foreign matter on the catalyst surface; at the same time, the hydrogen bubbles generated by the reduction of the catalyst surface will impact the gas-liquid phase channel. On this basis, by introducing a gas pressure pulse operation, the gas pressure fluctuation in the gas-liquid phase channel is strengthened to form a more violent impact, accelerate the formation of the gas transmission channel, and then achieve rapid activation.

Description

Technical Field

[0001] The present application belongs to the field of fuel cell technology, and in particular to a method for rapid activation of a high-temperature methanol fuel cell. Background Art

[0002] High-Temperature Methanol Fuel Cell (HTMFC) is a new type of clean energy technology that uses methanol as fuel to directly or indirectly generate electricity through electrochemical reactions under high temperature conditions. This technology has significant characteristics such as high energy conversion efficiency, low emissions, and environmental friendliness, and is regarded as one of the important development directions of future clean energy technology.

[0003] Activation refers to the process of transforming a fuel cell from its initial state to one with good electrochemical activity, which is crucial for the startup, operation and long-term stability of the fuel cell. During the activation process, the fuel cell forms an effective electrochemical reaction interface, which helps to improve the power density and energy conversion efficiency of the battery. Rapid completion of activation means that the battery can reach its optimal working state faster, thereby maintaining a high performance level throughout the operating cycle.

[0004] At the same time, during the activation process, the fuel cell may consume additional energy to reach the working state. Quickly completing the activation can reduce the energy consumption at this stage, thereby improving the overall energy efficiency. This has a positive effect on reducing operating costs and improving the economy of fuel cells.

[0005] Existing patents mainly target conventional low-temperature hydrogen fuel cells. For example, CN114883605A provides an online activation strategy based on gas purge and variable load, CN113363536A provides a short-circuit activation strategy, CN113224353A provides a cathode under-gas activation strategy, and CN112952149A provides an activation strategy based on humidity control.

[0006] However, for high-temperature fuel cells, the activation effect and activation rate of the above activation strategy cannot meet actual production needs. Summary of the invention

[0007] The main purpose of the present application is to provide a rapid activation method for a high-temperature methanol fuel cell, so as to solve the problem of poor activation effect and activation efficiency of high-temperature fuel cells in the prior art.

[0008] In order to achieve the above objectives, according to one aspect of the present application, a method for rapid activation of a high-temperature methanol fuel cell is provided, wherein the method is to achieve rapid activation of the fuel cell by performing electrochemical reduction treatment and gas pressure pulse treatment on the fuel cell.

[0009] The electrochemical reduction operation of the present application should be carried out when the fuel cell is within the operable temperature range. First, the anode fuel gas (H2) is injected into the fuel cell to the amount of gas required for the electrochemical reduction operation. An electric current is slowly applied between the positive and negative electrodes of the fuel cell to form an electrochemical hydrogen pump in the fuel cell, that is, a hydrogen oxidation reaction occurs at the anode and a hydrogen reduction reaction occurs at the cathode.

[0010] This application is based on the internal characteristics of high-temperature fuel cells and achieves in-situ removal of foreign matter on the catalyst surface by introducing an electrochemical reduction operation. At the same time, the hydrogen bubbles generated by the reduction of the catalyst surface will impact the gas-liquid phase channel. On this basis, by introducing a gas pressure pulse operation, the gas pressure fluctuation in the gas-liquid phase channel is enhanced to form a more violent impact, thereby accelerating the formation of the gas transmission channel and achieving rapid activation.

[0011] Furthermore, the electrochemical reduction treatment and the gas pressure pulse treatment are performed simultaneously.

[0012] The gas pressure pulse operation of the present application can be performed synchronously with the electrochemical reduction operation, so that the cathode and anode gas pressures fluctuate periodically.

[0013] Furthermore, the electrochemical reduction treatment comprises the following steps:

[0014] S1: heating the fuel cell to its operating temperature T;

[0015] S2: injecting fuel gas into the anode of the fuel cell to a preset amount;

[0016] S3: Connect the positive electrode of the power source to the negative electrode of the fuel cell, connect the negative electrode of the power source to the positive electrode of the fuel cell, and apply current to a preset current value;

[0017] S4: Maintain the fuel cell operating state until time t1;

[0018] S5: Reduce the current value to 0 and reduce the temperature of the fuel cell to a shutdown state.

[0019] In the method of the present application, the fuel gas injected into the anode is selected from hydrogen.

[0020] Furthermore, in step S1, the operating temperature T is 120-200°C.

[0021] Furthermore, in step S2, the cathode of the fuel cell is connected to the external environment (i.e., an environment open to the atmosphere), and the preset amount of fuel gas is the required gas amount corresponding to the current value used during the electrochemical reduction treatment; at this time, in step S5, the current value is reduced to 0, the anode fuel gas supply is stopped first, and then the fuel cell temperature is reduced to a shutdown state.

[0022] Furthermore, in step S2, when the cathode of the fuel cell is connected to the anode of the fuel cell, the preset amount of fuel gas is an amount that replaces and fills the entire fuel cell gas pipeline, and the cathode outlet and the anode outlet are closed.

[0023] When the electrochemical reduction operation is performed in the method of the present application, the cathode and anode gas pipelines can independently form an open system or be connected to form a closed system.

[0024] When the cathode of the fuel cell of the present application is connected to the external environment, the electrochemical reduction operation adopts direct current.

[0025] Furthermore, when the cathode of the fuel cell is connected to the external environment or the cathode of the fuel cell is connected to the anode of the fuel cell in step S2, the current applied in step S3 is a direct current; the preset direct current value is 0.05 to 2 times the rated working current; and the time t1 is 0.5 to 120 minutes.

[0026] Furthermore, the preset DC current value I1 is 0.05 to 2 times the rated working current.

[0027] Furthermore, the preset DC current value I1 is 0.1 to 1 times the rated working current.

[0028] Furthermore, the preset DC current value I1 is 0.2~1, 0.3~1, 0.4~1, 0.5~1, 0.6~1, 0.7~1 or 0.8~1 times the rated working current.

[0029] Further, the time t1 is 0.5 to 120 minutes, and further, the time t1 is 1 to 120 minutes, 5 to 120, 10 to 120, 20 to 120, 30 to 120, 40 to 120, 50 to 120, 60 to 130, 70 to 120, 80 to 120, 90 to 120, 100 to 120 or 110 to 120 minutes.

[0030] When the cathode and anode of the fuel cell of the present application are connected to form a closed system, the electrochemical reduction operation current can be direct current or alternating current.

[0031] Further, when the cathode of the fuel cell is connected to the anode of the fuel cell in step S2, the current applied is an alternating current.

[0032] Furthermore, the preset absolute value of the alternating current I2 is 0.05 to 2 times of the rated working current.

[0033] Furthermore, the frequency of the alternating current is 0.1 to 10 Hz, and the waveform is a square wave or a sine wave.

[0034] Furthermore, the preset alternating current value I2 is 0.05~2, 0.1~2, 0.2~2, 0.3~2, 0.4~2, 0.5~2, 0.6~2, 0.7~2, 0.8~2, 0.9~2, 1~2, 1.2~2, 1.5~2 or 1.8~2 times the rated working current.

[0035] Further, the frequency of the alternating current is 0.1 ~ 10 Hz, 0.5 ~ 10 Hz, 1 ~ 10 Hz, 2 ~ 10 Hz, 3 ~ 10 Hz, 4 ~ 10 Hz, 5 ~ 10 Hz, 6 ~ 10 Hz, 7 ~ 10 Hz, 8 ~ 10 Hz or 9 ~ 10 Hz.

[0036] Furthermore, the air pressure pulse processing comprises the following steps:

[0037] S1: heating the fuel cell to its operating temperature T;

[0038] S2: When the fuel cell is in operation, a gas pressure pulse is applied to the fuel cell gas pipeline;

[0039] Among them, the lower limit value of the gas pipeline pressure, the upper limit value of the pressure and the pulse period are set;

[0040] S3: Maintain the fuel cell operating state until time t2;

[0041] S4: Set the fuel cell to a shutdown state.

[0042] Furthermore, in step S2, after the gas pipeline of the cathode of the fuel cell and the gas pipeline of the anode of the fuel cell are connected, a gas pressure pulse is performed on the entire gas pipeline of the fuel cell.

[0043] Furthermore, in step S2, gas pressure pulses are separately applied to the gas pipeline of the cathode of the fuel cell and the gas pipeline of the anode of the fuel cell.

[0044] Further, in step S2, the lower pressure limit is -50 ~ 0 kPa, the upper pressure limit is 0 ~ 100 kPa; the pulse period is 0.5 ~ 10 seconds, and the pulse signal waveform is one of a square wave, a sine wave, a sawtooth wave, and a triangle wave; and the time t2 is 0.5 ~ 120 minutes.

[0045] Further, the pressure lower limit P1 is -40 ~ 0 kPa, -30 ~ 0 kPa, -20 ~ 0 kPa, -10 ~0 kPa, -5 ~ 0 kPa; the pressure upper limit P2 is 10 ~ 100 kPa, 20 ~ 100 kPa, 30 ~ 100 kPa, 40 ~ 100 kPa, 50 ~ 100 kPa, 60 ~ 100 kPa, 70 ~ 100 kPa, 80 ~ 100 kPa, 90 ~ 100 kPa.

[0046] Further, the pulse period τ is 1 to 10 seconds, 1 to 10 seconds, 2 to 10 seconds, 3 to 10 seconds, 4 to 10 seconds, 5 to 10 seconds, 6 to 10 seconds, 7 to 10 seconds, 8 to 10 seconds, and 9 to 10 seconds.

[0047] Furthermore, the time t2 is 0.5 to 120 minutes.

[0048] Further, the time t2 is 1 to 120 minutes, 5 to 120, 10 to 120, 20 to 120, 30 to 120, 40 to 120, 50 to 120, 60 to 130, 70 to 120, 80 to 120, 90 to 120, 100 to 120 or 110 to 120 minutes.

[0049] Furthermore, the electrochemical reduction treatment and the gas pressure pulse treatment are repeated 2 to 4 times.

[0050] Compared with the prior art, this application has the following beneficial effects:

[0051] (1) The present application provides a method for rapid activation of a high-temperature methanol fuel cell. The method eliminates the discharge operation activation strategy of a conventional fuel cell and performs in-situ catalyst surface foreign matter removal and gas-liquid phase channel unblocking based on electrochemical reduction and gas pressure pulse operation. In principle, the method achieves a reduction in the activation polarization and mass transfer polarization inside the fuel cell, thereby greatly improving the cell activation efficiency.

[0052] (2) Based on the internal characteristics of high-temperature fuel cells, this application introduces an electrochemical reduction operation to achieve in-situ removal of foreign matter on the catalyst surface. At the same time, the hydrogen bubbles generated by the reduction of the catalyst surface will impact the gas-liquid phase channel. On this basis, by introducing a gas pressure pulse operation, the gas pressure fluctuation in the gas-liquid phase channel is enhanced to form a more violent impact, thereby accelerating the formation of the gas transmission channel and achieving rapid activation. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A schematic diagram of the test system of Example 1 of the present application is shown.

[0054] Figure 2 A control logic schematic diagram of Example 1 of the present application is shown.

[0055] Figure 3 The gas pressure pulse hydrogen pump activation data of Example 1 of the present application is shown.

[0056] Figure 4 The conventional steady-state operation activation data for comparison with Example 1 of the present application is shown.

[0057] Figure 5 A schematic diagram of the test system of Example 2 of the present application is shown. DETAILED DESCRIPTION

[0058] The present application is further described below in conjunction with specific embodiments. The following are only a few embodiments of the present application, and are not intended to limit the present application in any form. Although the present application discloses the following preferred embodiments, they are not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the above disclosed technical content to make some changes or modifications are equivalent to equivalent implementation cases and are within the scope of the technical solution.

[0059] Unless otherwise specified, the raw materials in the examples of the present application were purchased from commercial sources and used directly without any special treatment.

[0060] Example 1

[0061] The fuel cell uses a 10-cell high-temperature methanol fuel cell stack that has undergone a start-stop test. The test system diagram is shown in the figure below. Figure 1 As shown, the anode fuel used in the fuel cell is pure hydrogen. The anode flow / pressure controller 102 is connected to the anode inlet of the fuel cell stack 201, and the pressure fluctuation generator 103 is connected to the cathode outlet of the fuel cell stack 201; a stop valve 104 is provided between the anode outlet and the cathode inlet of the fuel cell stack 201; a stop valve 104 is provided outside the pressure fluctuation generator 103 to control the connection with the atmospheric environment; an anode gas source 101 is provided outside the anode flow / pressure controller 102 to control the introduction of hydrogen.

[0062] High-temperature methanol fuel cell stack rapid activation steps (control logic diagram as shown in Figure 2 As shown) are as follows:

[0063] S1, start the fuel cell stack temperature control module 202 and set the target temperature to 160°C;

[0064] S2. When the temperature of the stack reaches 120°C, open the cathode (connected to the atmosphere) outlet stop valve 104, and set the flow rate of the anode flow / pressure controller 102 (injecting hydrogen) to the theoretical hydrogen consumption of the stack rated current value;

[0065] S3. When the voltage of each cell in the stack is ≤0.05V, the flow rate of the anode flow / pressure controller 102 is adjusted to 0, and the anode outlet stop valve 104 is closed, and the hydrogen completes the replacement and fills the fuel cell gas pipeline;

[0066] S4, setting the anode flow / pressure controller 102 to pressure control, and setting the anode pressure to 15 kPa, starting the power control module 205 after the anode pressure reaches a preset value, and setting the DC current to 1 times the rated current;

[0067] S5, start the pressure fluctuation generator 103, set the upper pressure limit to 30 kPa, the lower pressure limit to 0 kPa, and the pulse waveform to adopt a sawtooth wave with a cycle period of 10 s;

[0068] S6. After the fuel cell stack has been running for 20 minutes, the pressure fluctuation generator 103 and the power control module 205 are turned off, and the fuel cell stack is shut down and cooled to a shutdown state.

[0069] Comparative Example 1

[0070] S1. Heat the stack to the stack starting temperature of 120°C;

[0071] S2: Air and hydrogen are passed through (hydrogen is supplied to the anode inlet and exhausted at the outlet, air is supplied to the cathode inlet and exhausted at the outlet), the stack is discharged, and the stack temperature continues to rise to 160°C;

[0072] S3: During the heating process, the discharge current gradually increases with the temperature to the activation current I (the gradual increase is 50%I, 75%I, 100%I as the gradient)

[0073] S4: Stable operation at activation current I for 2 hours.

[0074] S5: Shutdown

[0075] The data of the process of Example 1 using a gas pressure pulse hydrogen pump for activation are as follows Figure 3 As shown, compared with the activation data of the traditional activation method (constant current steady state operation for 2 hours) Figure 4 As shown, the performance is improved by 18.4% after activation using a gas pressure pulse hydrogen pump, while the traditional activation method only improves by 7.2%. In addition, the activation time of the gas pressure pulse hydrogen pump is 20 minutes, while the traditional activation time is 2 hours. Therefore, the activation efficiency of the fuel cell stack can be greatly improved through the gas pressure pulse hydrogen pump activation operation.

[0076] Example 2

[0077] In this embodiment 2, the fuel cell uses a 10-cell high-temperature methanol fuel cell stack, and the test system schematic diagram is as follows: Figure 5 As shown, the voltage acquisition module 204 uses an external spring-type probe 203 to collect the voltage of each battery in the stack, and the anode fuel used in the fuel cell is pure hydrogen. Among them, the anode flow / pressure controller 102 is connected to the anode inlet of the fuel cell stack 201, and the pressure fluctuation generator 103 is connected to the cathode outlet of the fuel cell stack 201; a shut-off valve 104 is provided outside the pressure fluctuation generator 103 to control the connection with the atmospheric environment; an anode gas source 101 is provided outside the anode flow / pressure controller 102 to control the introduction of hydrogen.

[0078] The steps for rapid activation of high-temperature methanol fuel cell stacks are as follows:

[0079] S1, start the fuel cell stack temperature control module 202 and set the target temperature to 160°C;

[0080] S2. When the stack temperature reaches 120°C, open the cathode (connected to the atmosphere) outlet stop valve 104 and set the anode flow / pressure controller 102 (injecting hydrogen) to 1 kPa;

[0081] S3. When the voltage of each cell in the stack is ≤0.05V, the ventilation is terminated, the cathode outlet stop valve 104 is closed, the cathode and the anode are connected, and the hydrogen completes the replacement and filling of the fuel cell gas pipeline;

[0082] S4, setting the pressure of anode flow / pressure controller 102 to 30 kPa;

[0083] S5. When the anode pressure reaches the preset value, the power supply control module 205 is started, and the AC current is set to 0.5 times the rated current, and the waveform adopts a sine wave with a frequency of 0.5 Hz;

[0084] S6, start the pressure fluctuation generator 103, set the upper pressure limit to 100 kPa, the lower pressure limit to 10 kPa, and the pulse waveform to a square wave with a cycle period of 10 s;

[0085] S7. After the fuel cell stack has been running for 20 minutes, the pressure fluctuation generator 103 and the power control module 205 are turned off, and the fuel cell stack is shut down and cooled to a shutdown state.

[0086] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for rapid activation of a high-temperature methanol fuel cell, characterized in that: The method is to activate the fuel cell by subjecting the fuel cell to electrochemical reduction treatment and gas pressure pulse treatment; The steps for rapid activation of high-temperature methanol fuel cell stacks are as follows: S1, starting the fuel cell stack temperature control module (202), setting the target temperature to T, T is 120-200°C; S2. When the temperature of the stack reaches the target temperature T, the stop valve (104) at the cathode outlet is opened, the stop valve (104) at the anode outlet is opened, and the flow rate of the anode flow / pressure controller (102) is set to the theoretical hydrogen consumption at the rated current value of the stack; The stop valve (104) at the cathode outlet is connected to the atmosphere, and the flow rate of the anode flow / pressure controller (102) is the flow rate of the injected hydrogen; S3, when the voltage of each cell of the stack is ≤0.05 V, the flow rate of the anode flow / pressure controller (102) is adjusted to 0, the stop valve (104) of the anode outlet is closed, the stop valve (104) of the cathode outlet is closed, and the hydrogen gas is replaced and fills the fuel cell gas pipeline; S4, setting the anode flow / pressure controller (102) to pressure control, and setting the anode pressure to 15 kPa, and starting the power control module (205) after the anode pressure reaches a preset value, and setting the DC current to 0.05 to 2 times the rated working current; S5, start the pressure fluctuation generator (103), set the upper pressure limit to 30 kPa, the lower pressure limit to 0 kPa, the pulse period to 0.5 to 10 seconds, and the pulse signal waveform to be one of a square wave, a sine wave, a sawtooth wave, and a triangle wave; S6, when the fuel cell stack has been running for 0.5 to 120 minutes, the pressure fluctuation generator (103) and the power control module (205) are turned off, and the fuel cell stack is shut down and cooled to a shutdown state; The anode flow / pressure controller (102) is connected to the anode inlet of the fuel cell stack (201), and the pressure fluctuation generator (103) is connected to the cathode outlet of the fuel cell stack (201); A stop valve (104) is provided between the anode outlet and the cathode inlet of the fuel cell stack (201); A stop valve (104) is provided outside the pressure fluctuation generator (103) to control communication with the atmospheric environment; An anode gas source (101) is provided outside the anode flow / pressure controller (102) to control the introduction of hydrogen.

2. A method for rapid activation of a high-temperature methanol fuel cell, characterized in that: The method is to activate the fuel cell by subjecting the fuel cell to electrochemical reduction treatment and gas pressure pulse treatment; The steps for rapid activation of high-temperature methanol fuel cell stacks are as follows: S1, starting the fuel cell stack temperature control module (202), setting the target temperature to T, T is 120-200°C; S2. When the temperature of the battery stack reaches the target temperature T, the stop valve (104) at the cathode outlet is opened, and the pressure of the anode flow / pressure controller (102) is set to 1 kPa; The stop valve (104) at the cathode outlet is connected to the atmosphere, and the pressure of the anode flow / pressure controller (102) is the pressure of the injected hydrogen; S3, when the voltage of each cell of the stack is ≤0.05 V, the ventilation is terminated, the stop valve (104) at the cathode outlet is closed, and the hydrogen completes the replacement and filling of the fuel cell gas pipeline; S4, setting the pressure of the anode flow / pressure controller (102) to 30 kPa; S5, when the anode pressure reaches a preset value, starting the power control module (205), setting the absolute value of the alternating current to 0.05 to 2 times the rated working current; the frequency of the alternating current to 0.1 to 10 Hz, and the waveform to be a square wave or a sine wave; S6, starting the pressure fluctuation generator (103), setting the upper pressure limit to 100 kPa, the lower pressure limit to 10 kPa, the pulse period to 0.5 to 10 seconds, and the pulse signal waveform to be one of a square wave, a sine wave, a sawtooth wave, and a triangle wave; S7, when the fuel cell stack has been running for 0.5 to 120 minutes, the pressure fluctuation generator (103) and the power control module (205) are turned off, and the fuel cell stack is shut down and cooled to a shutdown state; The anode flow / pressure controller (102) is connected to the anode inlet of the fuel cell stack (201), and the pressure fluctuation generator (103) is connected to the cathode outlet of the fuel cell stack (201); A stop valve (104) is provided outside the pressure fluctuation generator (103) to control communication with the atmospheric environment; An anode gas source (101) is provided outside the anode flow / pressure controller (102) to control the introduction of hydrogen.

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