Activation method of fuel cell

Abstract

The invention discloses a method for activating a proton exchange membrane fuel cell. The specific process is as follows: S1) preparing a small molecular organic acid solution with a certain concentration; s2) introducing the solution prepared in the step S1 into a fuel cell according to a certain flow rate, and activating for a certain time; s3) after activation of the small molecular organic acid is completed, flushing the fuel cell with deionized water for 2-3 times; s4) connecting the fuel cell to a fuel cell test system, purging the fuel cell with N2, and setting the temperatures of the humidifier, the gas path pipeline and the cell at the same time; s5) after reaching the specified temperature, replacing the reaction gas air and H2, testing an I-V curve, and determining the maximum current; s6) activating for a certain time under the maximum current density; s7) after activation is completed, an I-V curve is obtained through testing, and the limiting current density and the peak power density can be obtained.According to the method, the proton exchange membrane fuel cell is subjected to small-molecule organic acid activation through the efficient method, and compared with a traditional activation method, the limiting current density and the peak power density of fuel cell operation are obviously improved.

Description

Technical Field

[0001] The invention belongs to the field related to fuel cell technology and relates to a proton exchange membrane fuel cell activation method. Background Art

[0002] A fuel cell is a chemical device that directly converts the chemical energy of a fuel into electrical energy. It converts part of the Gibbs free energy in the chemical energy of the fuel into electrical energy through an electrochemical reaction. It is not limited by the Carnot cycle effect and is therefore highly efficient.

[0003] For the proton exchange membrane fuel cell (PEMFC) after assembly, activation is an important step in "awakening" the fuel cell. Usually, the membrane electrode (MEA) needs to be activated, and the purpose of the so-called activation process is to make it reach the rated or optimal performance. The activation of PEMFC can improve the activity of the platinum catalyst, increase the utilization rate of the catalyst, strengthen the hydration of the proton exchange membrane, and improve the output performance of the fuel cell. During the activation process, the rated or peak power density of the battery will continue to increase until it reaches a constant level, which indicates that the battery has been activated. Zhu Ke et al. (Chinese Journal of Power Sourcess, 2002, 26(4): 267–268, 325) compared three activation processes: constant current natural activation, constant current forced activation, and variable current forced activation. However, the activation time of the three activation methods exceeded 4 hours, and even the constant current activation exceeded 10 hours. M Zhiani et al. (Fuel Cells, 13 (5) (2013), pp. 946-955) proposed constant voltage and constant current activation methods, both of which take more than ten hours, seriously increasing the consumption of raw materials such as hydrogen. Irmawati et al. (Energy Procedia, 2015, 68: 311–317) proposed a four-stage activation process, which starts from the open circuit voltage and loads to 0.6 V, then generates electricity at a constant voltage for 1 h at this operating point, and then returns to the open circuit voltage, repeating 4 times. The PEMFC performance is improved, but the activation time exceeds 4 h. Silva et al. (Journal of Electroanalytical Chemistry, 2012, 671: 58-66) proposed a segmented activation method, which first operates under open circuit conditions for a period of time, and then loads for 1 h in steps and segments. The battery performance is improved after six cycles, but this type of activation method generally takes from six hours to dozens of hours. The above activation methods not only seriously reduce the production efficiency of fuel cells, but also lead to a large amount of raw material consumption and increase production costs.

[0004] Therefore, the selection of MEA activation method is very important to the performance of PEMFC. A reasonable activation method can not only improve the performance of PEMFC, but also greatly reduce the activation time and reduce the amount of gas fuel, thereby significantly reducing unnecessary hydrogen consumption and reducing activation costs. Summary of the invention

[0005] The purpose of the present invention is to provide a proton exchange membrane fuel cell activation method, aiming to find a method for improving the performance of a proton exchange membrane fuel cell. The present invention is achieved by providing a proton exchange membrane fuel cell activation method, comprising the following steps: S1. Prepare a small molecule organic acid solution of a certain concentration; S2, introducing the solution prepared in S1 into the cathode air inlet of the fuel cell by a feed pump, and activating the small molecule organic acid for a period of time at a certain flow rate; S3. After the activation of the small molecule organic acid is completed, the fuel cell is rinsed with deionized water 2-3 times; S4, connecting the fuel cell to the fuel cell test system and purging it with N2, while setting the temperature of the humidifier, gas pipeline and battery; S5. After reaching the specified temperature, replace the reaction gas with air and H2, test the IV curve, and increase the current density in sequence until the voltage is no longer stable within a few minutes; S6. Determine the limiting current density based on the polarization curve data of S5, and activate for a period of time at the current density; S7. After activation is completed, the IV curve is obtained by testing, and the data is processed to obtain the limiting current density and peak power density.

[0006] Furthermore, the small molecule organic acid solution required for the configuration described in step S1 is a 99.0% to 99.8% small molecule organic acid commonly found on the market, typically formic acid, acetic acid, lactic acid, mandelic acid, malic acid, glycolic acid, etc. Such organic acids can be used alone or in combination.

[0007] Furthermore, the concentration of the small molecule organic acid solution in step S1 needs to be configured to be 2% to 5%.

[0008] Furthermore, the fuel cell chip (CCM) assembled in step S2 is a common CCM on the market.

[0009] Furthermore, the assembled gas diffusion layer (GDL) in step S2 is a common gas diffusion layer for electrochemical experiments on the market.

[0010] Furthermore, in step S2, the solution prepared in S1 is introduced into the cathode air inlet of the fuel cell by a feed pump, and small molecule organic acid activation is performed for a period of time at a certain flow rate, usually at 20-80 mL / min.

[0011] Furthermore, in step S2, the small molecule organic acid activation is performed at a certain flow rate for a period of time, and the small molecule organic acid activation time is 0.3 to 2 h.

[0012] Furthermore, the activation discharge time in step S6 is 0.5 to 1 h.

[0013] The method for activating a proton exchange membrane fuel cell with a small molecule organic acid completed by the above steps is applied in the fuel cell activation test stage.

[0014] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0015] The experimental materials used in the present invention are all commercially available.

[0016] The positive and progressive effects of the present invention are: (1) Reduce single-cell experimental test time and test costs and improve activation efficiency; (2) Reduce the number of times the battery is flooded at high current density; (3) Significantly improve the limiting current density and peak power density of single cell operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a polarization curve diagram of the fuel cell after activation according to Example 1 of the present invention.

[0018] Figure 2 This is a polarization curve diagram of the fuel cell after activation according to Example 2 of the present invention.

[0019] Figure 3 This is a polarization curve diagram of the fuel cell after activation according to Example 3 of the present invention.

[0020] Figure 4 This is a polarization curve diagram of the fuel cell after activation according to Example 4 of the present invention.

[0021] Figure 5 This is a polarization curve diagram of the fuel cell after activation according to Example 5 of the present invention.

[0022] Figure 6 This is the polarization curve of the fuel cell after activation in Comparative Example 1. DETAILED DESCRIPTION

[0023] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principle of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are selected according to conventional methods and conditions, or according to the product instructions. Example

[0024] Prepare 2% formic acid solution in a beaker; The prepared 2% formic acid solution was introduced into the cathode air inlet of the fuel cell by a feed pump, and small molecule organic acid activation was performed at a flow rate of 50 mL / min for 0.5 h; After formic acid activation was completed, the fuel cell was flushed three times with deionized water; The fuel cell was connected to the fuel cell test system, and the membrane electrode surface was cleaned by N2 purge. At the same time, the anode humidifier temperature was set to 70°C, the cathode humidifier temperature was set to 50°C, the cathode and anode gas pipeline temperatures were set to 70°C, and the battery temperature was set to 70°C; After reaching the specified temperature, the reaction gas was replaced with air and H2, and the IV curve was tested, and the current density was increased successively until the voltage was no longer stable within a few minutes; Find the limiting current density of 2.20 A / cm2 corresponding to the final voltage stability under the first cycle polarization curve data 2 , activated at this current density for 0.5 h; After activation is completed, the IV curve is obtained by testing and the saved data is processed to obtain the limiting current density and peak power density. Figure 1 As shown, the limiting current density is 2.21 A / cm 2 , the peak power density is 1.16 W / cm 2 . Example

[0025] Prepare 3% glacial acetic acid solution in a beaker; The prepared 3% glacial acetic acid solution was introduced into the cathode air inlet of the fuel cell by a feed pump, and small molecule organic acid activation was performed at a flow rate of 50 mL / min for 1 h; After activation with glacial acetic acid, the fuel cell was rinsed three times with deionized water; The fuel cell was connected to the fuel cell test system, and the membrane electrode surface was cleaned by N2 purge. At the same time, the anode humidifier temperature was set to 70°C, the cathode humidifier temperature was set to 50°C, the cathode and anode gas pipeline temperatures were set to 70°C, and the battery temperature was set to 70°C; After reaching the specified temperature, the reaction gas was replaced with air and H2, and the IV curve was tested, and the current density was increased successively until the voltage was no longer stable within a few minutes; Find the limiting current density 2.00 A / cm2 corresponding to the last voltage stability under the first cycle polarization curve data 2 , activated at this current density for 0.5 h; After activation is completed, the IV curve is obtained by testing and the saved data is processed to obtain the limiting current density and peak power density. Figure 2 As shown, the limiting current density is 2.25 A / cm 2 , peak power density is 1.20 W / cm 2 . Example

[0026] Prepare 4% lactic acid solution in a beaker; The prepared 4% lactic acid solution was introduced into the cathode air inlet of the fuel cell by a feed pump, and small molecule organic acid activation was performed at a flow rate of 50 mL / min for 1.5 h; After the lactic acid activation is completed, the fuel cell is rinsed 2-3 times with deionized water; The fuel cell was connected to the fuel cell test system, and the membrane electrode surface was cleaned by N2 purge. At the same time, the anode humidifier temperature was set to 70°C, the cathode humidifier temperature was set to 50°C, the cathode and anode gas pipeline temperatures were set to 70°C, and the battery temperature was set to 70°C; After reaching the specified temperature, the reaction gas was replaced with air and H2, and the IV curve was tested, and the current density was increased successively until the voltage was no longer stable within a few minutes; The limiting current density corresponding to the stable final voltage under the first cycle polarization curve data is 2.11 A / cm 2 , activated at this current density for 0.5 h; After activation is completed, the IV curve is obtained by testing and the saved data is processed to obtain the limiting current density and peak power density. Figure 3 As shown, the limiting current density is 2.22 A / cm 2 , the peak power density is 1.19 W / cm 2 . Example

[0027] Prepare 5% mandelic acid solution in a beaker; The prepared 5% mandelic acid solution was introduced into the cathode air inlet of the fuel cell by a feed pump, and small molecule organic acid activation was performed at a flow rate of 50 mL / min for 2 h; After activation of mandelic acid was completed, the fuel cell was rinsed three times with deionized water; The fuel cell was connected to the fuel cell test system, and the membrane electrode surface was cleaned by N2 purge. At the same time, the anode humidifier temperature was set to 70°C, the cathode humidifier temperature was set to 50°C, the cathode and anode gas pipeline temperatures were set to 70°C, and the battery temperature was set to 70°C; After reaching the specified temperature, the reaction gas was replaced with air and H2, and the IV curve was tested, and the current density was increased successively until the voltage was no longer stable within a few minutes; Find the limiting current density of 2.24 A / cm2 corresponding to the final voltage stability under the first cycle polarization curve data 2 , activated at this current density for 0.5 h; After activation is completed, the IV curve is obtained by testing and the saved data is processed to obtain the limiting current density and peak power density. Figure 4 As shown, the limiting current density is 2.30 A / cm 2 , the peak power density is 1.18 W / cm 2 . Example

[0028] Prepare a mixed solution of 2% formic acid and 4% lactic acid in a beaker; The prepared 2% formic acid and 4% lactic acid mixed solution was introduced into the cathode air inlet of the fuel cell by a feed pump, and small molecule organic acid activation was performed at a flow rate of 50 mL / min for 1 h; After activation of mandelic acid was completed, the fuel cell was rinsed three times with deionized water; The fuel cell was connected to the fuel cell test system, and the membrane electrode surface was cleaned by N2 purge. At the same time, the anode humidifier temperature was set to 70°C, the cathode humidifier temperature was set to 50°C, the cathode and anode gas pipeline temperatures were set to 70°C, and the battery temperature was set to 70°C; After reaching the specified temperature, the reaction gas was replaced with air and H2, and the IV curve was tested, and the current density was increased successively until the voltage was no longer stable within a few minutes; Find the limiting current density of 2.23 A / cm2 corresponding to the final voltage stability under the first cycle polarization curve data 2 , activated at this current density for 0.5 h; After activation is completed, the IV curve is obtained by testing and the saved data is processed to obtain the limiting current density and peak power density. Figure 5 As shown, the limiting current density is 2.29 A / cm 2 , the peak power density is 1.14 W / cm 2 .

[0029] Comparative Example 1 First, the four-stage activation method proposed by Irmawati et al. (Energy Procedia, 2015, 68: 311–317) was followed: the voltage was loaded from the open circuit to 0.6 V, constant voltage power generation was performed at this operating point for 1 h, and then the voltage was returned to the open circuit voltage, and this was repeated 4 times; Then connect the assembled fuel cell to the fuel cell test system, and clean the membrane electrode surface with N2 purge, and set the anode humidifier temperature to 70℃, the cathode humidifier temperature to 50℃, the cathode and anode gas pipeline temperature to 70℃, and the battery temperature to 70℃; After reaching the specified temperature, the reaction gas was replaced with air and H2, and the IV curve was tested, and the current density was increased successively until the voltage was no longer stable within a few minutes; Find the limiting current density of 2.12 A / cm2 corresponding to the final voltage stability under the first cycle polarization curve data 2 , activated at this current density for 0.5 h; After activation is completed, the IV curve is obtained by testing and the saved data is processed to obtain the limiting current density and peak power. Figure 6 As shown, the limiting current density is 2.19 A / cm 2 , peak power is 0.96 W / cm 2 .

[0030] serial number <![CDATA[Current density (A / cm 2 ).]]> <![CDATA[Battery peak power density (W / cm 2 ).]]> Example 1 2.21 1.16 Example 2 2.25 1.20 Example 3 2.22 1.19 Example 4 2.30 1.18 Example 5 2.29 1.14 Comparative Example 1 2.19 0.96

Claims

1. A method for activating a proton exchange membrane fuel cell, characterized in that: The following steps are involved: S1. Prepare a small molecule organic acid solution of a certain concentration; S2, introducing the solution prepared in S1 into the cathode air inlet of the fuel cell by a feed pump, and activating the small molecule organic acid for a period of time at a certain flow rate; S3. After the activation of the small molecule organic acid is completed, the fuel cell is rinsed with deionized water 2-3 times; S4, connecting the fuel cell to the fuel cell test system and purging it with N2, while setting the temperature of the humidifier, gas pipeline and battery; S5. After reaching the specified temperature, replace the reaction gas with air and H2, test the IV curve, and increase the current density in sequence until the voltage is no longer stable within a few minutes; S6. Determine the limiting current density based on the polarization curve data of S5, and activate for a period of time at the current density; S7. After activation is completed, the IV curve is obtained by testing, and the data is processed to obtain the limiting current density and peak power density.

2. According to the proton exchange membrane fuel cell activation method described in claim 1 S1, the small molecule organic acid is formic acid, acetic acid, lactic acid, mandelic acid, malic acid and glycolic acid, etc. Such organic acids can be used alone or in combination.

3. According to the proton exchange membrane fuel cell activation method of claim 1 S1, the concentration of the small molecule organic acid used for activation is 1-5%; The proton exchange membrane fuel cell activation method according to claim 1 S2 is characterized in that: The solution prepared in S1 is introduced into the cathode air inlet of the fuel cell by a feed pump, and small molecule organic acid activation is performed for a period of time at a certain flow rate, and the flow rate is set to 20-80 mL / min; The proton exchange membrane fuel cell activation method according to claim 1 S2 is characterized in that: The solution prepared by S1 is introduced into the cathode air inlet of the fuel cell by a feed pump, and small molecule organic acid activation is performed at a certain flow rate for a period of time, which lasts for 0.3 to 2 hours; The proton exchange membrane fuel cell activation method according to claim 1 S3 is characterized in that: After activation with small molecule organic acid, rinse with deionized water 2-3 times, each washing time is 10 ~ 15 minutes; The proton exchange membrane fuel cell activation method according to claim 1 S4 is characterized in that the assembled fuel cell is connected to a fuel cell test system and purged with N2, and the temperature of the humidifier, gas pipeline and battery is set to 70°C; The proton exchange membrane fuel cell activation method according to claim 1 S5 is characterized in that: Under normal fuel cell test conditions, test IV to determine the maximum current; The proton exchange membrane fuel cell activation method according to claim 1 S6 is characterized in that: The activation was carried out for 10 to 60 min at the maximum current density in S5.

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