A method for activating a fuel cell

Abstract

The present invention provides a method for activating a fuel cell, comprising the following steps: (1) subjecting a fuel cell stack to one-step continuous cycle forced current activation under conditions of a temperature ≥70°C and a humidity ≥90%; (2) shutting down and heat-insulating the fuel cell stack obtained by the one-step continuous cycle forced current activation; and (3) restarting the stack to perform two-step forced current activation to complete the activation. In the method for activating a fuel cell according to the present invention, the activation time can be controlled within 2 to 3 hours, which greatly shortens the activation time of the fuel cell, improves the activation efficiency, and reduces energy consumption.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel cells and relates to an activation method for a fuel cell. Background Art

[0002] Fuel cell performance depends largely on the performance of the membrane electrode assembly (MEA). The performance of MEA components (e.g., electrocatalyst, proton exchange membrane, gas diffusion layer, etc.) or CCM components (e.g., electrocatalyst, proton exchange membrane), as well as the MEA or CCM manufacturing process, significantly impacts performance. However, for a given MEA or CCM, effective fuel cell activation is necessary to ensure it reaches and maximizes its inherent optimal performance within a short period of time. Therefore, newly manufactured fuel cells typically require activation to achieve optimal performance.

[0003] The commonly used activation methods so far are: (1) variable current forced activation; (2) constant current forced activation; (3) constant current natural activation. The activation time of constant current forced activation and constant current natural activation is generally greater than 20 hours, while the activation time of variable current forced activation is more than 6 hours.

[0004] CN108232243A discloses a method for activating a proton exchange membrane fuel cell, comprising: introducing humidified nitrogen into the cathode of the proton exchange membrane fuel cell, introducing humidified hydrogen into the anode, and checking the air tightness of the proton exchange membrane fuel cell; setting the battery operating temperature; after reaching the set temperature, continuously maintaining the cathode nitrogen and anode hydrogen for 2 to 3 hours; converting the gas introduced into the cathode into humidified oxygen and / or air, performing a polarization performance test and / or a cyclic voltammetry test on the proton exchange membrane fuel cell for 5 to 10 times, again converting the gas introduced into the cathode into humidified nitrogen and maintaining this for 10 to 20 minutes; and repeating step 4 10 to 20 times until the polarization performance of the proton exchange membrane fuel cell remains stable.

[0005] The method proposed in CN102097631A wets the MEAs with deionized water after assembly. However, controlling the distribution of deionized water within the stack makes it difficult to ensure adequate wetting of each MEA, resulting in long wetting times and poor results. Furthermore, direct deionized water wetting can leave a large amount of liquid water in the stack, complicating subsequent activation processes, such as constant current activation, and even leading to flooding and polarity reversal. Furthermore, the thickness of the MEAs changes due to MEA wetting, requiring further adjustments to the stack fixture, complicating the activation process.

[0006] The aforementioned solutions suffer from long activation times or overly complex activation processes. To achieve sufficient activation, fuel cell activation often requires several or even dozens of hours to complete, which is extremely disadvantageous for commercial fuel cell production. Furthermore, the activation process consumes large amounts of hydrogen and occupies equipment resources for a long time, resulting in low resource utilization. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for activating a fuel cell. In the method for activating a fuel cell of the present invention, the activation time can be controlled within 2 to 3 hours, which greatly shortens the activation time of the fuel cell, improves the activation efficiency, and reduces energy consumption.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for activating a fuel cell, the method comprising the following steps:

[0010] (1) The fuel cell stack is subjected to a one-step continuous cycle forced current activation under conditions of temperature ≥ 70°C and humidity ≥ 90%;

[0011] (2) Cutting off the gas, discharging and reducing the voltage of the fuel cell stack, and shutting down the stack to keep it warm;

[0012] (3) Restart the fuel cell stack and perform two-step forced variable current activation to complete the activation.

[0013] The present invention activates the fuel cell stack under high temperature and high humidity conditions, which can not only reduce activation energy consumption and save activation costs, but also improve activation efficiency and reduce activation time, thereby improving the utilization rate of the fuel cell testing device.

[0014] Preferably, the temperature of the one-step continuous cycle forced current activation in step (1) is 70-95°C, for example: 70°C, 80°C, 85°C, 90°C or 95°C.

[0015] Preferably, the humidity of the one-step continuous cycle forced variable current activation in step (1) is 90-100%, for example: 90%, 92%, 95%, 98% or 100%.

[0016] Preferably, the time of the one-step continuous cycle forced variable current activation in step (1) is 0.5 to 1 h, for example: 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h or 1 h, etc.

[0017] Preferably, the current density of the one-step continuous cycle forced current activation in step (1) is 0.05 to 2 A / cm 2, for example: 0.05A / cm 2 , 0.1A / cm 2 , 0.5A / cm 2 , 0.9A / cm 2 , 1A / cm 2 , 1.5A / cm 2 , 1.8A / cm 2 or 2A / cm 2 wait.

[0018] Preferably, the current density of the discharge voltage reduction treatment in step (2) is 8 to 12 mA / cm 2 , for example: 8mA / cm 2 , 9mA / cm 2 , 10mA / cm 2 , 11mA / cm 2 or 12mA / cm 2 wait.

[0019] Preferably, the endpoint voltage of the discharge voltage reduction treatment is 0.1-0.15V, for example, 0.1V, 0.11V, 0.12V, 0.13V, 0.14V or 0.15V.

[0020] The automatic release process of the fuel cell discharge stop voltage is slow, and when operating at a high potential, it will affect the catalyst of the fuel cell stack, causing the catalyst to agglomerate and the proton membrane to become thinner. Therefore, the present invention reduces the time the fuel cell stack stays at a high potential by discharging at a low electric density after the fuel cell stack stops supplying gas, and avoids the fuel cell stack staying at a high potential for too long as much as possible, which may affect the performance of the fuel cell stack.

[0021] Preferably, the temperature for the shutdown and heat preservation in step (2) is 25-30°C, for example: 25°C, 26°C, 27°C, 28°C, 29°C or 30°C, etc.

[0022] Preferably, the shutdown and heat preservation time is 0.8 to 1.2 hours, for example, 0.8 hours, 0.9 hours, 1 hour, 1.1 hours or 1.2 hours.

[0023] Preferably, the temperature of the two-step continuous cycle forced current activation in step (3) is 70-95°C, for example: 70°C, 80°C, 85°C, 90°C or 95°C.

[0024] Preferably, the humidity of the two-step continuous cycle forced variable current activation in step (3) is 90-100%, for example: 90%, 92%, 95%, 98% or 100%.

[0025] Preferably, the time of the two-step continuous cycle forced variable current activation in step (3) is 0.5 to 1 h, for example: 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h or 1 h, etc.

[0026] Preferably, the current density of the two-step continuous cycle forced current activation in step (3) is 0.05-2A / cm 2 , for example: 0.05A / cm 2 , 0.1A / cm 2 , 0.5A / cm 2 , 0.9A / cm 2 , 1A / cm 2 , 1.5A / cm 2 , 1.8A / cm 2 or 2A / cm 2 wait.

[0027] As a preferred embodiment of the present invention, the activation method comprises the following steps:

[0028] (1) The fuel cell stack is placed at 70-95°C and 90-100% humidity with a current of 0.05-2 A / cm 2 The current density was used for 0.5 to 1 h of one-step continuous cycle forced current activation;

[0029] (2) Cut off the gas and apply 8-12 mA / cm 2 Discharge at a current density of 1000V and drop the voltage to 0.1-0.15V, then stop and keep warm at 25-30℃ for 0.8-1.2h;

[0030] (3) Restart the stack and operate at 0.05-2A / cm2 at 70-95°C and 90-100% humidity. 2 The activation was completed by performing two-step forced variable current activation for 0.5 to 1 h at a current density of 100 nm.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The fuel cell activation method of the present invention significantly shortens the hydrogen ventilation time of traditional fuel cell activation, saves hydrogen consumption, and the activation time can be shortened to 2 to 3 hours.

[0033] (2) The method of the present invention can not only reduce activation energy consumption and save activation costs, but also improve activation efficiency and reduce activation time, thereby improving the utilization rate of the fuel cell test device. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The activation performance comparison of the fuel cell obtained by the activation method described in Example 1 and Comparative Example 1 is shown in FIG. Figure 1 As shown, V1 is the polarization curve after the stack activation of Example 1, and V2 is the polarization curve after the stack activation of Comparative Example 1. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0036] Example 1

[0037] This embodiment provides a fuel cell activation method, which includes the following steps:

[0038] (1) The fuel cell stack was placed under the conditions of temperature 80°C and humidity 95%, respectively at 0.1A / cm 2 , 0.5A / cm 2 , 0.9A / cm 2 , 1.1A / cm 2 , 1.5A / cm 2 , 1.8A / cm 2 Stay for 3 minutes, then quickly reduce the load, and perform three rounds of continuous forced discharge and load activation within 1 hour (one-step continuous cycle forced current activation);

[0039] (2) After one-step continuous cycle forced current activation, stop the gas supply and conduct the fuel cell stack at 10 mA / cm 2 The discharge current density was 0.12V, and the stack was quickly cooled to 30°C and maintained for 1 hour.

[0040] (3) Restart the stack at 82°C and 93% humidity, respectively at 0.1A / cm 2 , 0.5A / cm 2 , 0.9A / cm 2 , 1.1A / cm 2 , 1.5A / cm 2 , 1.8A / cm 2 Stay for 3 minutes, then quickly reduce the load, and perform two rounds of continuous forced discharge and load activation within 40 minutes.

[0041] Example 2

[0042] This embodiment provides a fuel cell activation method, which includes the following steps:

[0043] (1) The fuel cell stack was placed under the conditions of temperature of 90°C and humidity of 98%, and the 2 , 0.4A / cm2 , 1A / cm 2 , 1.2A / cm 2 , 1.6A / cm 2 , 1.8A / cm 2 After a 3.2-minute dwell, the load was rapidly reduced, and three rounds of continuous forced discharge and load-changing activation were performed within 1 hour (one-step continuous cycle forced current-changing activation).

[0044] (2) After one-step continuous cycle forced current activation, stop the gas supply and conduct the fuel cell stack at 11 mA / cm 2 The discharge current density was 0.14V, and the stack was quickly cooled to 30℃ and maintained for 1h.

[0045] (3) Restart the stack at 93°C and 99% humidity, respectively at 0.2A / cm 2 , 0.4A / cm 2 , 1A / cm 2 , 1.2A / cm 2 , 1.6A / cm 2 , 1.8A / cm 2 Stay for 3.2 minutes, then quickly reduce the load, and perform two rounds of continuous forced discharge and load activation within 40 minutes.

[0046] Example 3

[0047] This embodiment provides a fuel cell activation method, which includes the following steps:

[0048] (1) The fuel cell stack was placed under the conditions of temperature 80°C and humidity 95%, respectively at 0.1A / cm 2 , 0.5A / cm 2 , 0.9A / cm 2 , 1.1A / cm 2 , 1.5A / cm 2 , 1.8A / cm 2 Stay for 3 minutes, then quickly reduce the load, and perform three rounds of continuous forced discharge and load activation within 1 hour (one-step continuous cycle forced current activation);

[0049] (2) After one-step continuous cycle forced current activation, stop the gas supply and conduct the fuel cell stack at 10 mA / cm 2 The discharge current density was set to 0.12V, and the stack was quickly cooled to 20℃ and kept for 1h.

[0050] (3) Restart the stack at 82°C and 93% humidity, respectively at 0.1A / cm 2, 0.5A / cm 2 , 0.9A / cm 2 , 1.1A / cm 2 , 1.5A / cm 2 , 1.8A / cm 2 Stay for 3 minutes, then quickly reduce the load, and perform two rounds of continuous forced discharge and load activation within 40 minutes.

[0051] A comparison of Examples 1 and 3 shows that the shutdown temperature is too low to achieve enhanced MEA wetting. At low temperatures, thermal motion is reduced, significantly reducing the diffusion of water within the MEA. This results in reduced water wetting during the one-hour shutdown period.

[0052] Example 4

[0053] This embodiment provides a fuel cell activation method, which includes the following steps:

[0054] (1) The fuel cell stack was placed under the conditions of temperature 80°C and humidity 95%, respectively at 0.1A / cm 2 , 0.5A / cm 2 , 0.9A / cm 2 , 1.1A / cm 2 , 1.5A / cm 2 , 1.8A / cm 2 Stay for 3 minutes, then quickly reduce the load, and perform three rounds of continuous forced discharge and load activation within 1 hour (one-step continuous cycle forced current activation);

[0055] (2) After one-step continuous cycle forced current activation, stop the gas supply and conduct the fuel cell stack at 10 mA / cm 2 The discharge current density was 0.12V, and the stack was quickly cooled to 35°C and maintained for 1 hour.

[0056] (3) Restart the stack at 82°C and 93% humidity, respectively at 0.1A / cm 2 , 0.5A / cm 2 , 0.9A / cm 2 , 1.1A / cm 2 , 1.5A / cm 2 , 1.8A / cm 2 Stay for 3 minutes, then quickly reduce the load, and perform two rounds of continuous forced discharge and load activation within 40 minutes.

[0057] From the comparison between Example 1 and Example 4, it can be seen that the shutdown insulation temperature is too high, causing the water vapor in the MEA of the fuel cell stack to evaporate too quickly, and it is impossible to form a dynamic water vapor balance. The MEA gradually tends to a dry state, causing some catalysts to be unable to fully hydrate during the next operation of the fuel cell stack, resulting in performance degradation.

[0058] Comparative Example 1

[0059] This comparative example provides a conventional fuel cell activation method, which includes the following steps:

[0060] (1) Turn on the battery, set the stack temperature to 70°C, and the humidification temperature on both sides to 60°C;

[0061] (2) Turn on the battery, set the battery temperature to 60°C, and set the humidification temperature on both sides to 70°C;

[0062] (3) Turn on the battery, set the unit temperature to 70℃, and the humidification temperature on both sides to 60℃.

[0063] Step 2 and step 3 are similar to step 1, except that the stack temperature and humidification temperature are different.

[0064] A test cycle consists of several loading IV cycles. The pressure during the loading process is the pressure generated by the natural flow resistance.

[0065] The loading current density reached 1.5 A / cm in each polarization curve. 2 The battery is discharged at a constant current for 30 minutes, and then the load is reduced. A new round of polarization is performed when the load is reduced to 0.1A / cm2. The activation process is terminated when the voltage of each loading voltage decreases compared to the previous round or the voltage value remains unchanged at each loading voltage during the last three rounds of activation loading.

[0066] The activation performance comparison of the fuel cell obtained by the activation method described in Example 1 and Comparative Example 1 is shown in the figure below. Figure 1 As shown, V1 is the polarization curve after the stack activation of Example 1 of the present application, and V2 is the polarization curve after the stack activation of Comparative Example 1. Figure 1 It can be seen that, compared with the general forced variable load discharge method, the activation method of the present invention shortens the hydrogen ventilation time to one third of the original time, saves the amount of hydrogen used, and shortens the activation time to 3 hours.

[0067] Comparative Example 2

[0068] The only difference between this comparative example and Example 1 is that the activation humidity is 80%, and the other conditions and parameters are exactly the same as those in Example 1.

[0069] From the comparison between Example 1 and Comparative Example 2, it can be seen that the activation humidity of the activation method of the present invention needs to be controlled at above 90%. If the humidity is too low, the catalyst of the fuel cell stack cannot be fully hydrated during the loading and discharging process, the catalyst activity cannot be fully released, and the fuel cell stack performance cannot be fully exerted during the discharge process.

[0070] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for activating a fuel cell, characterized in that: The activation method comprises the following steps: (1) The fuel cell stack is placed at 70-95°C and 90-100% humidity with a current of 0.05-2 A / cm 2 The current density was used for 0.5 to 1 h of one-step continuous cycle forced current activation; (2) Cut off the gas and apply 8-12 mA / cm 2 Discharge at a current density of 1000V and drop the voltage to 0.1-0.15V, then stop and keep warm at 25-30℃ for 0.8-1.2h; (3) Restart the fuel cell stack and operate at 0.05-2 A / cm2 at 70-95°C and 90-100% humidity. 2 The activation was completed by performing two-step continuous cycle forced current activation for 0.5 to 1 h at a current density of 100 nm.

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