A method for rapid activation of a fuel cell stack
By employing a rapid activation method that utilizes the activation process of fuel cell stacks through changes in humidified gas and current density, the problems of long activation time and high gas consumption in existing technologies have been solved, achieving efficient stack performance improvement and cost reduction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENZHEN SENERGY FUEL CELL TECH CO LTD
- Filing Date
- 2023-03-31
- Publication Date
- 2026-06-02
AI Technical Summary
Existing fuel cell stacks have long activation times and high gas consumption, resulting in low production efficiency and high costs.
A rapid activation method is adopted, which includes the stack wetting, loading and unloading processes. The wetting effect is controlled by combining the humidifying gas and current density changes, and the cathode undergassing process is used to remove impurities and optimize the stack performance.
It significantly shortens activation time, reduces energy consumption and production costs, and improves fuel cell stack performance.
Smart Images
Figure CN116387563B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of fuel cell technology, and particularly relates to a rapid activation method for fuel cell stacks. Background Technology
[0002] Proton exchange membrane fuel cells (PEMFCs) have attracted much attention in the transportation sector due to their advantages such as low operating temperature, zero emissions, high power density, and high efficiency. However, newly manufactured fuel cells often have performance limitations due to contamination from impurities during the production process, failing to meet practical application requirements. Therefore, activation is necessary before the fuel cell stack is assembled into a fuel cell system for normal use, enabling the fuel cell to achieve optimal output performance.
[0003] During the activation process, the performance of the fuel cell stack gradually improves and reaches stability. However, this process usually takes several hours or even days, which not only increases gas consumption but also limits production efficiency, becoming one of the reasons for the high cost of fuel cell stacks. Summary of the Invention
[0004] This invention provides a rapid activation method for fuel cell stacks, aiming to solve the problems of long activation time and high gas consumption in existing technologies.
[0005] The present invention is implemented as follows: a rapid activation method for a fuel cell stack includes the following steps:
[0006] (1) The fuel cell stack is wetted by the following method: the fuel cell stack is heated to the first preset temperature, humidified nitrogen gas is introduced into the anode and cathode, the dew point temperature is the second preset temperature, and the gas is introduced for a period of time; the second preset temperature is higher than the first preset temperature.
[0007] (2) The fuel cell stack is heated to the third preset temperature. Humidified hydrogen is introduced into the anode and humidified air is introduced into the cathode. The relative humidity of the hydrogen is the first relative humidity and the relative humidity of the air is equal to the relative humidity of the hydrogen.
[0008] The stack is loaded to a first current density at a first loading speed and kept constant for a first preset time. Then, the stack is loaded to a second current density at the first loading speed and kept constant for a second preset time. The hydrogen metering ratio in step (2) is the first metering ratio and the air metering ratio is the second metering ratio. Then, the current of the stack is reduced to zero at a first unloading speed and kept constant for a third preset time after the current is reduced to zero.
[0009] (3) Load the stack to the third current density at the second loading speed, maintain the current for the fourth preset time, and then continue to load the stack to the fourth current density at the second loading speed, maintain the current for the fifth preset time; the hydrogen metering ratio in step (3) is the third metering ratio, and the air metering ratio is the fourth metering ratio; then reduce the current of the stack to the fifth current density at the second unloading speed, make the cathode of the stack under-gas at the fifth current density, and then reduce the current of the stack to zero at the second unloading speed;
[0010] (4) Repeat step (3) several times to complete the rapid activation of the fuel cell stack and improve its performance;
[0011] The specific method for reducing the gas supply to the cathode of the fuel cell stack in step (3) is as follows: In constant current mode, rapidly reduce the air metering ratio to reduce the average individual voltage of the fuel cell stack to the first voltage value, maintain this for 10 to 30 seconds, restore the air supply, and continue constant current operation until the voltage stabilizes.
[0012] The undergassing process in step (3) utilizes the scarcity of oxidant to create reducing conditions at the cathode, which is beneficial for removing cathode impurities and oxides.
[0013] Furthermore, the first preset temperature in step (1) is 40–60°C, preferably 45–55°C. The second preset temperature is 5–10°C higher than the first preset temperature. The dew point temperature of the humidifying nitrogen (the second preset temperature) is higher than the stack temperature (the first preset temperature). When the humidifying nitrogen enters the fuel cell stack, it will produce a condensation effect, which can quickly moisten the inside of the fuel cell stack.
[0014] Furthermore, during the wetting process described in step (1), the internal resistance of the fuel cell stack is tested using an internal resistance meter. The duration of air circulation is determined by the internal resistance value of the fuel cell stack, and air circulation is stopped when the internal resistance no longer decreases. Detecting the internal resistance of the fuel cell stack during the wetting process to determine the wetting effect can effectively shorten the wetting time.
[0015] Furthermore, the third preset temperature mentioned in step (2) is 60-80℃.
[0016] Furthermore, the first relative humidity in step (2) is 30% to 80%, preferably 40% to 60%.
[0017] Furthermore, the first loading speed in step (2) is 5 to 10 A / s, and the first unloading speed is 10 to 20 A / s.
[0018] Furthermore, the first current density described in step (2) is 0.1–0.3 A / cm². 2 The second current density is 2.3–2.6 A / cm². 2 .
[0019] Furthermore, the first preset time in step (2) is 1 to 5 minutes, the second preset time is equal to the first preset time, and the third preset time is 1 to 3 minutes.
[0020] Furthermore, the first measurement ratio in step (2) is 1.5 to 2.0, and the second measurement ratio is 1.8 to 2.5.
[0021] Furthermore, the second loading speed in step (3) is 10-20 A / s, and the second unloading speed is 10-20 A / s.
[0022] Furthermore, the third current density mentioned in step (3) is equal to the first current density, the fourth current density is equal to the second current density, and the fifth current density is 0.6–1.2 A / cm². 2 .
[0023] Furthermore, the fourth preset time in step (3) is 1 to 5 minutes, and the fifth preset time is equal to the fourth preset time.
[0024] Furthermore, the third measurement ratio in step (3) is equal to the first measurement ratio, and the fourth measurement ratio is equal to the second measurement ratio.
[0025] Furthermore, in step (3), the air metering ratio is rapidly reduced, and the rapid reduction time is 1s-2s.
[0026] Furthermore, the first voltage value mentioned in step (3) during the undergassing process is 0.05 to 0.1V.
[0027] Furthermore, the sign that the activation is complete in step (4) is: comparing the voltage value of the stack after the cathode is under-gasified in two adjacent steps (3) until the voltage difference is less than or equal to 5mV.
[0028] Compared with the prior art, the present invention has the following beneficial effects:
[0029] 1. First, in step (1), humidifying nitrogen gas is introduced into the anode and cathode of the fuel cell stack. The dew point temperature of the nitrogen gas is higher than the stack temperature. When the humidifying nitrogen gas enters the fuel cell stack, it will produce a condensation effect, which can quickly moisten the inside of the fuel cell stack. During the wetting process, the internal resistance of the fuel cell stack is detected to judge the wetting effect, which can effectively shorten the wetting time.
[0030] 2. Secondly, through repeated loading in steps (2) and (3), the fuel cell stack is rapidly cyclical between high and low potentials, effectively promoting the construction of the three-phase interface and changes in the fine morphology of the catalyst. In addition, the water generated under high current can further wet the fuel cell stack, enabling the proton exchange membrane and catalyst layer to reach a good hydration state.
[0031] 3. The undergassing process in step (3) utilizes the scarcity of oxidant to create reducing conditions at the cathode, which is beneficial for removing cathode impurities and oxides.
[0032] The activation method described in this invention can specifically regulate the performance of the fuel cell stack. Compared with the prior art, the activation efficiency is greatly improved, and the activation energy consumption and production cost are reduced. Attached Figure Description
[0033] Figure 1 This is a comparison chart of performance after conventional activation and rapid activation in the examples. Detailed Implementation
[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0035] If the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.
[0036] Currently, existing fuel cell stack activation methods suffer from the following drawbacks: long activation time and high gas consumption. To address these technical problems, this invention proposes a rapid activation method for fuel cell stacks.
[0037] Example 1
[0038] The proton exchange membrane fuel cell stack used in this embodiment consists of 12 individual cells, with an effective membrane electrode area of 307 cm². 2 Before activation, the airtightness of the fuel cell stack is tested. After confirming that the airtightness is qualified, activation is carried out according to the following steps:
[0039] (1) The fuel cell stack is wetted by heating the fuel cell stack to 50°C and introducing humidified nitrogen gas with a dew point temperature of 55-60°C into the anode and cathode. During this process, the internal resistance of the fuel cell stack is detected by an internal resistance meter. After 15-20 minutes of gas introduction, the internal resistance of the fuel cell stack no longer decreases, and the wetting is completed.
[0040] (2) The fuel cell stack is heated to 70°C. Humidified hydrogen is introduced into the anode and humidified air is introduced into the cathode. The relative humidity of the hydrogen and air is controlled to be between 50% and 55%.
[0041] The fuel cell stack was loaded to 0.2 A / cm at a loading rate of 5 A / s. 2 The current was kept constant for 3 minutes, and then the fuel cell stack was continuously loaded at a loading rate of 5 A / s to 2.5 A / cm. 2 The current is kept constant for 3 minutes; the hydrogen metering ratio is 1.8 and the air metering ratio is 2.0 during this process; then, the current of the fuel cell stack is reduced to zero at a rate of 10 A / s, and the current is maintained at zero for 1 to 3 minutes.
[0042] (3) Load the fuel cell stack to 0.2 A / cm at a loading rate of 10 A / s. 2 The current was kept constant for 3 minutes, and then the fuel cell stack was continuously loaded at a loading rate of 10 A / s to 2.5 A / cm. 2 The current was kept constant for 3 minutes; the hydrogen metering ratio was 1.8 and the air metering ratio was 2.0 during this process; then the current of the fuel cell stack was reduced to 1.2 A / cm at a rate of 10 A / s. 2 This causes the cathode of the fuel cell to be under-gasified, and then the current in the fuel cell is reduced to zero at a rate of 10 A / s.
[0043] The specific method for addressing the insufficient air supply at the cathode of the fuel cell stack is as follows: In constant current mode, rapidly reduce the air metering ratio to reduce the average individual cell voltage of the fuel cell stack to 0.05–0.1V, maintain this for 10–30 seconds, then immediately restore the air supply and continue constant current operation until the voltage stabilizes.
[0044] (4) Repeat step (3) 5 times to complete the activation. The overall activation time should be controlled within 1.5 hours.
[0045] After the rapid activation process, the performance of the fuel cell stack was tested and compared with that of a fuel cell stack activated by conventional methods. The results are as follows: Figure 1 As shown in the figure, the activation method provided in Embodiment 1 of the present invention can achieve better results than traditional activation methods, and greatly shortens the activation time (within 1.5 hours), reducing energy consumption and production costs.
[0046] Example 2
[0047] The proton exchange membrane fuel cell stack used in this embodiment consists of 12 individual cells, with an effective membrane electrode area of 307 cm². 2 Before activation, the airtightness of the fuel cell stack is tested. After confirming that the airtightness is qualified, activation is carried out according to the following steps:
[0048] (1) The fuel cell stack is wetted by heating the fuel cell stack to 40°C and introducing humidified nitrogen gas with a dew point temperature of 45-50°C into the anode and cathode. During this process, the internal resistance of the fuel cell stack is detected by an internal resistance meter. After 15-20 minutes of gas introduction, the internal resistance of the fuel cell stack no longer decreases, and the wetting is completed.
[0049] (2) The fuel cell stack is heated to 60°C. Humidified hydrogen is introduced into the anode and humidified air is introduced into the cathode. The relative humidity of the hydrogen and air is controlled to be between 40% and 50%.
[0050] The fuel cell stack was loaded to 0.1 A / cm at a loading rate of 5 A / s. 2 The current was kept constant for 1 minute, and then the fuel cell stack was continuously loaded at a loading rate of 5 A / s to 2.3 A / cm. 2 The current is kept constant for 1 minute; the hydrogen metering ratio is 1.5 and the air metering ratio is 1.8 during this process; then, the current of the fuel cell stack is reduced to zero at a rate of 10 A / s, and the current is maintained at zero for 1 to 3 minutes.
[0051] (3) Load the fuel cell stack to 0.1 A / cm at a loading rate of 10 A / s. 2 The current was kept constant for 1 minute, and then the fuel cell stack was continuously loaded at a loading rate of 10 A / s to 2.3 A / cm². 2 The current was kept constant for 1 minute; the hydrogen metering ratio during this process was 1.5, and the air metering ratio was 1.8; then the current of the fuel cell stack was reduced to 0.6 A / cm at a rate of 10 A / s. 2 This causes the cathode of the fuel cell to be under-gasified, and then the current in the fuel cell is reduced to zero at a rate of 10 A / s.
[0052] The specific method for addressing the insufficient air supply at the cathode of the fuel cell stack is as follows: In constant current mode, rapidly reduce the air metering ratio to reduce the average individual cell voltage of the fuel cell stack to 0.05–0.1V, maintain this for 10–30 seconds, then immediately restore the air supply and continue constant current operation until the voltage stabilizes.
[0053] (4) Repeat step (3) 6 times to complete the activation. The overall activation time should be controlled within 1.5 hours.
[0054] After the rapid activation process, the performance of the fuel cell stack was tested and compared with that of a fuel cell stack after conventional activation. The activation method provided in Example 2 can achieve better results than traditional activation, and greatly shortens the activation time, reducing energy consumption and production costs.
[0055] Example 3
[0056] The proton exchange membrane fuel cell stack used in this embodiment consists of 12 individual cells, with an effective membrane electrode area of 307 cm². 2Before activation, the airtightness of the fuel cell stack is tested. After confirming that the airtightness is qualified, activation is carried out according to the following steps:
[0057] (1) The fuel cell stack is wetted by heating the fuel cell stack to 60°C and introducing humidified nitrogen gas with a dew point temperature of 65-70°C into the anode and cathode. During this process, the internal resistance of the fuel cell stack is detected by an internal resistance meter. After 15-20 minutes of gas introduction, the internal resistance of the fuel cell stack no longer decreases, and the wetting is completed.
[0058] (2) The fuel cell stack is heated to 80°C. Humidified hydrogen is introduced into the anode and humidified air is introduced into the cathode. The relative humidity of the hydrogen and air is controlled to be between 55% and 60%.
[0059] The fuel cell stack was loaded to 0.3 A / cm at a loading rate of 10 A / s. 2 The current was kept constant for 5 minutes, and then the fuel cell stack was continuously loaded at a loading rate of 10 A / s to 2.6 A / cm². 2 The current is kept constant for 5 minutes; the hydrogen metering ratio is 2.0 and the air metering ratio is 2.5 during this process; then, the current of the fuel cell stack is reduced to zero at a rate of 20 A / s, and the current is maintained at zero for 1 to 3 minutes.
[0060] (3) The fuel cell stack was loaded to 0.3 A / cm at a loading rate of 20 A / s. 2 The current was kept constant for 5 minutes, and then the fuel cell stack was continuously loaded at a loading rate of 20 A / s to 2.6 A / cm. 2 The current was kept constant for 5 minutes; the hydrogen metering ratio was 2.0 and the air metering ratio was 2.5 during this process; then the current of the fuel cell stack was reduced to 1.5 A / cm at a rate of 20 A / s. 2 This causes the cathode of the fuel cell to be under-gasified, and then the current in the fuel cell is reduced to zero at a rate of 20 A / s.
[0061] The specific method for addressing the insufficient air supply at the cathode of the fuel cell stack is as follows: In constant current mode, rapidly reduce the air metering ratio to reduce the average individual cell voltage of the fuel cell stack to 0.05-0.1V, then immediately restore the air supply and continue constant current operation until the voltage stabilizes.
[0062] (4) Repeat step (3) 4 times to complete the activation. The overall activation time should be controlled within 1.5 hours.
[0063] After the rapid activation process, the performance of the fuel cell stack was tested and compared with that of a fuel cell stack after conventional activation. The activation method provided in Example 3 can achieve better results than traditional activation, and greatly shortens the activation time, reducing energy consumption and production costs.
[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A rapid activation method for a fuel cell stack, characterized in that: Includes the following steps: (1) The fuel cell stack is wetted by heating the fuel cell stack to the first preset temperature, humidifying nitrogen gas is introduced into the anode and cathode, the dew point temperature is the second preset temperature, the gas is introduced for a period of time, and the gas is stopped when the internal resistance no longer decreases; the second preset temperature is higher than the first preset temperature. (2) The fuel cell stack is heated to the third preset temperature. Humidified hydrogen is introduced into the anode and humidified air is introduced into the cathode. The relative humidity of the hydrogen is the first relative humidity and the relative humidity of the air is equal to the relative humidity of the hydrogen. The stack is loaded to a first current density at a first loading speed and kept constant for a first preset time. Then, the stack is loaded to a second current density at the first loading speed and kept constant for a second preset time. The hydrogen metering ratio in step (2) is the first metering ratio and the air metering ratio is the second metering ratio. Then, the current of the stack is reduced to zero at a first unloading speed and kept constant for a third preset time after the current is reduced to zero. (3) Load the stack to the third current density at the second loading speed, maintain the current for the fourth preset time, and then continue to load the stack to the fourth current density at the second loading speed, maintain the current for the fifth preset time; the hydrogen metering ratio in step (3) is the third metering ratio, and the air metering ratio is the fourth metering ratio; then reduce the current of the stack to the fifth current density at the second unloading speed, make the cathode of the stack under-gas at the fifth current density, and then reduce the current of the stack to zero at the second unloading speed; (4) Repeat step (3) several times to complete the rapid activation of the fuel cell stack and improve its performance; The specific method for making the cathode of the fuel cell under-gas in step (3) is as follows: in constant current mode, rapidly reduce the air metering ratio to reduce the average single-cell voltage of the fuel cell to the first voltage value, maintain it for 10 to 30 seconds, restore the air supply, and continue constant current operation until the voltage stabilizes. The first loading speed in step (2) is 5-10 A / s, and the first unloading speed is 10-20 A / s; The first current density mentioned in step (2) is 0.1 to 0.3 A / cm. 2 The second current density is 2.3–2.6 A / cm². 2 ; The second loading speed in step (3) is 10-20 A / s, and the second unloading speed is 10-20 A / s; The third current density mentioned in step (3) is equal to the first current density, and the fourth current density is equal to the second current density.
2. The rapid activation method for a fuel cell stack according to claim 1, characterized in that: The first preset temperature in step (1) is 40-60℃; the second preset temperature is 5-10℃ higher than the first preset temperature.
3. The rapid activation method for a fuel cell stack according to claim 1, characterized in that: During the immersion process described in step (1), the internal resistance of the fuel cell stack is tested using an internal resistance meter, and the duration of the ventilation is determined by the internal resistance value of the fuel cell stack.
4. The rapid activation method for a fuel cell stack according to claim 1, characterized in that: The third preset temperature mentioned in step (2) is 60-80℃.
5. The rapid activation method for a fuel cell stack according to claim 1, characterized in that: The first relative humidity mentioned in step (2) is 30% to 80%.
6. The rapid activation method for a fuel cell stack according to claim 1, characterized in that: The first preset time in step (2) is 1 to 5 minutes, the second preset time is equal to the first preset time, and the third preset time is 1 to 3 minutes. The first measurement ratio in step (2) is 1.5 to 2.0, and the second measurement ratio is 1.8 to 2.
5.
7. The rapid activation method for a fuel cell stack according to claim 1, characterized in that: The fifth current density mentioned in step (3) is 0.6 to 1.2 A / cm². 2 ; The fourth preset time in step (3) is 1 to 5 minutes, and the fifth preset time is equal to the fourth preset time.
8. The rapid activation method for a fuel cell stack according to claim 1, characterized in that: The third measurement ratio in step (3) is equal to the first measurement ratio, and the fourth measurement ratio is equal to the second measurement ratio; The first voltage value mentioned in step (3) during the undergassing process is 0.05 to 0.1V.
9. The rapid activation method for a fuel cell stack according to claim 1, characterized in that: The activation completion sign in step (4) is: compare the voltage value of the stack after the cathode is under-gas in two adjacent steps (3) until the voltage difference is less than or equal to 5mV.