A method for improving the stability of catalysts on the surfaces of anodes and cathodes of proton exchange membrane fuel cells

Abstract

The application discloses a method for improving the stability of catalysts on the surface of anode and cathode of a proton exchange membrane fuel cell, and is based on the theoretical achievement of "improving the service life of the cell by an applied electric field". The field source and electric field distribution mode are designed in a targeted manner, the catalyst separation speed and the aging rate of the membrane are reduced by the more directional electric field force, the metal dissolution process of the catalyst is inhibited, the proton transmission path is stabilized, and the service life of the membrane electrode is significantly improved. The proton exchange membrane fuel cell has great potential in the energy field of fixed energy storage, wind-solar complementary power and power driving.

Description

Technical Field

[0001] This invention belongs to the field of fuel cells, specifically relating to a method for improving the stability of catalysts on the anode and cathode surfaces of a proton exchange membrane fuel cell. Background Technology

[0002] Electric field science is a relatively unexplored area in the technological development of proton exchange membrane fuel cells, and external electric fields and related technologies are even rarer to report. The few invention patents that exist are as follows: Guo Jianguo et al. found that an external electric field can increase the proton diffusion rate in the exchange membrane, reduce the short-circuit current in the membrane (CN 101540409), and further improve the device structure (CN103208641).

[0003] Wang Guangjun et al. used an external electric field to improve the catalyst reaction rate (CN 104882619); Chen Haihui et al. constructed an electric field-enhanced reaction unit to expand the electrode reaction interface (CN 104868148); Chen Qing et al. used an alternating electric field to heat the fuel cell and improve the cold start rate of the battery (109148912).

[0004] However, current reports mainly focus on the impact of applied electric fields on battery power density. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the object of this invention is to overcome the shortcomings of the prior art and provide a method for improving the stability of catalysts on the anode and cathode surfaces of a proton exchange membrane fuel cell, comprising,

[0008] Applying an external electric field in the same direction as the internal electric field of a proton exchange membrane fuel cell improves the stability of the catalysts on the cathode and anode surfaces inside the cell.

[0009] As a preferred embodiment of the method described in this invention, the proton exchange membrane fuel cell comprises,

[0010] The membrane electrode, field electrode, and gas diffusion layer; among which,

[0011] The membrane electrode consists of a proton exchange membrane, a cathode catalytic layer, and an anode catalytic layer.

[0012] The field electrode is composed of a controllable DC power supply, a cathode field electrode, and an anode field electrode. The cathode field electrode is connected to the positive terminal of the controllable DC power supply, and the anode field electrode is connected to the negative terminal of the controllable DC power supply.

[0013] The membrane electrode and gas diffusion layer are positioned at the center of the cathode field electrode and the anode field electrode;

[0014] The cathode catalytic layer and the cathode field electrode are on the same side, the anode catalytic layer and the anode field electrode are on the same side, and the cumulative thickness of the cathode field electrode and the anode field electrode is the same as the cumulative thickness of the membrane electrode and the gas diffusion layer.

[0015] In a preferred embodiment of the method described in this invention, both the cathode field electrode and the anode field electrode are composed of a conductive layer and an isolation layer.

[0016] In a preferred embodiment of the method described in this invention, applying an external electric field includes,

[0017] The voltage of the controllable DC power supply is controlled to apply an external electric field;

[0018] The voltage value V is determined by the field density P of the membrane electrode, the area S of the cathode catalyst layer, the distance L between the cathode field electrode and the anode field electrode, and the correction coefficient k. The relationship is: V = L × S / P × k.

[0019] Among these requirements, the voltage value V must be above 0V, the spacing L must be less than 1cm, and the area must not exceed 100m². 2 The correction factor k ranges from 0 to 1.

[0020] As a preferred embodiment of the method described in this invention, the application of the external electric field further includes,

[0021] The applied electric field starts synchronously with the battery discharge. If the battery rest time is less than 10 hours, the applied electric field will continue to be applied during the rest period.

[0022] If the battery rest time is greater than 10 hours, apply an external electric field for 1 to 3 hours before the next battery discharge.

[0023] Stop applying the external electric field when the battery power density decays to below 10%.

[0024] In a preferred embodiment of the method described in this invention, the proton exchange membrane is one or more of Nafion membrane, PBI membrane, and POP membrane.

[0025] In a preferred embodiment of the method described in this invention, the cathode catalyst layer (102) and the anode catalyst layer (103) are one or more of a platinum-carbon catalyst, an iron-carbon catalyst, and a nitrogen-carbon catalyst, wherein the mass fraction of platinum in the platinum-carbon catalyst is 0.1-40 wt.%, the mass fraction of iron in the iron-carbon catalyst is 0.1-20 wt.%, and the mass fraction of nitrogen in the nitrogen-carbon catalyst is 0.1-20 wt.%.

[0026] In a preferred embodiment of the method described in this invention, the conductive layer is one or more of copper foil, iron foil, aluminum foil, titanium foil, and lead foil.

[0027] In a preferred embodiment of the method described in this invention, the isolation layer is one or more of insulating rubber pads, insulating plastic pads, and insulating tape.

[0028] In a preferred embodiment of the method described in this invention, the gas diffusion layer is one or more of carbon paper, carbon cloth, and carbon felt.

[0029] Beneficial effects of this invention:

[0030] (1) The present invention has designed the field source and electric field distribution in a targeted manner, relying on a more directional electric field force to reduce the catalyst detachment rate and membrane aging rate, suppress the metal dissolution process of the catalyst, stabilize the proton transport path, and significantly improve the membrane electrode lifetime.

[0031] (2) The proton exchange membrane fuel cell of the present invention has great potential in energy fields such as stationary energy storage, wind and solar hybridization, and power drive.

[0032] (3) The present invention proposes a unique electric field application method for the life of proton exchange membrane fuel cells, which significantly improves the life of proton exchange membrane fuel cells. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0034] Figure 1 This is a schematic diagram of the exchange membrane fuel cell structure in an embodiment of the present invention.

[0035] Figure 2 This is a schematic diagram of the field electrode structure in an embodiment of the present invention.

[0036] Figure 3The graphs show linear scan curves of the oxygen reduction reaction under different electric field directions in the embodiments of the present invention; where a represents an applied electric field opposite to the reaction electric field, and b represents an applied electric field with the same electric field as the reaction electric field.

[0037] Figure 4 The graphs show linear scanning curves of the hydroxide reaction under different electric field directions in the embodiments of the present invention; where a represents an applied electric field opposite to the reaction electric field, and b represents an applied electric field with the same electric field as the reaction electric field. Detailed Implementation

[0038] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0039] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0040] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0041] Example 1

[0042] This embodiment provides a method for improving the stability of catalysts on the anode and cathode surfaces of a proton exchange membrane fuel cell, the main steps of which are as follows:

[0043] (1) Assembling a proton exchange membrane fuel cell: Refer to Figure 1 and Figure 2 Specifically, the battery consists of a membrane electrode 100, a field electrode 200, and a gas diffusion layer 300, with an assembly pressure of 4 MPa.

[0044] The membrane electrode 100 is composed of a Nafion membrane 101, a cathode platinum-carbon catalyst layer (platinum mass fraction of 20 wt.%) 102, and an anode platinum-carbon catalyst layer (platinum mass fraction of 20 wt.%) 103;

[0045] The field electrode 200 is composed of a controllable DC power supply 201, a cathode field electrode 202, and an anode field electrode 203; both the cathode field electrode 202 and the anode field electrode 203 are composed of copper foil 2021 and insulating rubber pad 2022.

[0046] The membrane electrode 100 and the gas diffusion layer (carbon paper) 300 are placed at the center of the cathode field electrode 202 and the anode field electrode 203. The cathode platinum carbon catalyst layer 102 and the cathode field electrode 202 are on the same side. The anode platinum carbon catalyst layer 103 and the anode field electrode 203 are on the same side. The cumulative thickness of the cathode field electrode 202 and the anode field electrode 203 is the same as the cumulative thickness of the membrane electrode 100 and the gas diffusion layer (carbon paper) 300.

[0047] The cathode field electrode 202 is connected to the positive terminal of the controllable DC power supply 201, and the anode field electrode 203 is connected to the negative terminal of the controllable high voltage DC power supply 201.

[0048] (2) Applying an external electric field:

[0049] The voltage of the controllable DC power supply 201 is controlled to apply an external electric field;

[0050] The voltage value V is determined by the field density P of the membrane electrode 100, the area S of the cathode catalyst layer 102, the distance L between the cathode field electrode 202 and the anode field electrode 203, and the correction coefficient k. The relationship is: V = L × S / P × k.

[0051] The voltage value (V) is 1.2V, the spacing (L) is 0.1cm, and the area (S) is 12cm². 2 The field density (P) is 2Vcm⁻¹, and the correction factor (k) is 0.5.

[0052] The applied electric field starts synchronously with the battery discharge. If the battery rest time is less than 10 hours, the applied electric field will continue to be applied during the rest time. If the battery rest time is more than 10 hours, the applied electric field will be applied for 2 hours before the next battery discharge.

[0053] Stop applying the external electric field when the battery power density decays to below 10%.

[0054] Example 2

[0055] This embodiment provides a method for improving the stability of catalysts on the anode and cathode surfaces of a proton exchange membrane fuel cell, the main steps of which are as follows:

[0056] (1) Assembling a proton exchange membrane fuel cell: Refer to Figure 1 and Figure 2 Specifically, the battery consists of a membrane electrode 100, a field electrode 200, and a gas diffusion layer 300, with an assembly pressure of 2 MPa.

[0057] The membrane electrode 100 is composed of a Nafion membrane 101, a cathode platinum-carbon catalyst layer (platinum mass fraction of 20 wt.%) 102, and an anode platinum-carbon catalyst layer (platinum mass fraction of 20 wt.%) 103;

[0058] The field electrode 200 is composed of a controllable DC power supply 201, a cathode field electrode 202, and an anode field electrode 203; both the cathode field electrode 202 and the anode field electrode 203 are composed of copper foil 2021 and insulating rubber pad 2022.

[0059] The membrane electrode 100 and the gas diffusion layer (carbon paper) 300 are placed at the center of the cathode field electrode 202 and the anode field electrode 203. The cathode platinum carbon catalyst layer 102 and the cathode field electrode 202 are on the same side. The anode platinum carbon catalyst layer 103 and the anode field electrode 203 are on the same side. The cumulative thickness of the cathode field electrode 202 and the anode field electrode 203 is the same as the cumulative thickness of the membrane electrode 100 and the gas diffusion layer (carbon paper) 300.

[0060] The cathode field electrode 202 is connected to the positive terminal of the controllable DC power supply 201, and the anode field electrode 203 is connected to the negative terminal of the controllable high voltage DC power supply 201.

[0061] (2) Applying an external electric field:

[0062] The voltage of the controllable DC power supply 201 is controlled to apply an external electric field;

[0063] The voltage value V is determined by the field density P of the membrane electrode 100, the area S of the cathode catalyst layer 102, the distance L between the cathode field electrode 202 and the anode field electrode 203, and the correction coefficient k. The relationship is: V = L × S / P × k.

[0064] The voltage (V) is 1.2V, the spacing (L) is 0.1cm, and the area (S) is 12cm². 2 The field density (P) is 2Vcm⁻¹, and the correction factor (k) is 0.5.

[0065] The applied electric field starts synchronously with the battery discharge. If the battery rest time is less than 10 hours, the applied electric field continues to be applied during the rest period. If the battery rest time is more than 10 hours, the applied electric field is applied for 2 hours before the next battery discharge.

[0066] Stop applying the external electric field when the battery power density decays to below 10%.

[0067] Example 3

[0068] This embodiment provides a method for improving the stability of catalysts on the anode and cathode surfaces of a proton exchange membrane fuel cell, the main steps of which are as follows:

[0069] (1) Assembling a proton exchange membrane fuel cell: Refer to Figure 1 and Figure 2 Specifically, the battery consists of a membrane electrode 100, a field electrode 200, and a gas diffusion layer 300, with an assembly pressure of 6 MPa.

[0070] The membrane electrode 100 is composed of a Nafion membrane 101, a cathode platinum-carbon catalyst layer (platinum mass fraction of 20 wt.%) 102, and an anode platinum-carbon catalyst layer (platinum mass fraction of 20 wt.%) 103;

[0071] The field electrode 200 is composed of a controllable DC power supply 201, a cathode field electrode 202, and an anode field electrode 203; both the cathode field electrode 202 and the anode field electrode 203 are composed of copper foil 2021 and insulating rubber pad 2022.

[0072] The membrane electrode 100 and the gas diffusion layer (carbon paper) 300 are placed at the center of the cathode field electrode 202 and the anode field electrode 203. The cathode platinum carbon catalyst layer 102 and the cathode field electrode 202 are on the same side. The anode platinum carbon catalyst layer 103 and the anode field electrode 203 are on the same side. The cumulative thickness of the cathode field electrode 202 and the anode field electrode 203 is the same as the cumulative thickness of the membrane electrode 100 and the gas diffusion layer (carbon paper) 300.

[0073] The cathode field electrode 202 is connected to the positive terminal of the controllable DC power supply 201, and the anode field electrode 203 is connected to the negative terminal of the controllable high voltage DC power supply 201.

[0074] (2) Applying an external electric field:

[0075] The voltage of the controllable DC power supply 201 is controlled to apply an external electric field;

[0076] The voltage value V is determined by the field density P of the membrane electrode 100, the area S of the cathode catalyst layer 102, the distance L between the cathode field electrode 202 and the anode field electrode 203, and the correction coefficient k. The relationship is: V = L × S / P × k.

[0077] The voltage (V) is 1.2V, the spacing (L) is 0.1cm, and the area (S) is 12cm². 2 The field density (P) is 2Vcm⁻¹, and the correction factor (k) is 0.5.

[0078] The applied electric field starts synchronously with the battery discharge. If the battery rest time is less than 10 hours, the applied electric field continues to be applied during the rest period. If the battery rest time is more than 10 hours, the applied electric field is applied for 2 hours before the next battery discharge.

[0079] Stop applying the external electric field when the battery power density decays to below 10%.

[0080] Example 4

[0081] This embodiment provides a method for improving the stability of catalysts on the anode and cathode surfaces of a proton exchange membrane fuel cell, the main steps of which are as follows:

[0082] (1) Assembling a proton exchange membrane fuel cell: Refer to Figure 1 and Figure 2 Specifically, the battery consists of a membrane electrode 100, a field electrode 200, and a gas diffusion layer 300, with an assembly pressure of 4 MPa.

[0083] The membrane electrode 100 is composed of a Nafion membrane 101, a cathode platinum-carbon catalyst layer (platinum mass fraction of 20 wt.%) 102, and an anode platinum-carbon catalyst layer (platinum mass fraction of 20 wt.%) 103;

[0084] The field electrode 200 is composed of a controllable DC power supply 201, a cathode field electrode 202, and an anode field electrode 203; both the cathode field electrode 202 and the anode field electrode 203 are composed of copper foil 2021 and insulating rubber pad 2022.

[0085] The membrane electrode 100 and the gas diffusion layer (carbon paper) 300 are placed at the center of the cathode field electrode 202 and the anode field electrode 203. The cathode platinum carbon catalyst layer 102 and the cathode field electrode 202 are on the same side. The anode platinum carbon catalyst layer 103 and the anode field electrode 203 are on the same side. The cumulative thickness of the cathode field electrode 202 and the anode field electrode 203 is the same as the cumulative thickness of the membrane electrode 100 and the gas diffusion layer (carbon paper) 300.

[0086] The cathode field electrode 202 is connected to the positive terminal of the controllable DC power supply 201, and the anode field electrode 203 is connected to the negative terminal of the controllable high voltage DC power supply 201.

[0087] (2) Applying an external electric field:

[0088] The voltage of the controllable DC power supply 201 is controlled to apply an external electric field;

[0089] The voltage value V is determined by the field density P of the membrane electrode 100, the area S of the cathode catalyst layer 102, the distance L between the cathode field electrode 202 and the anode field electrode 203, and the correction coefficient k. The relationship is: V = L × S / P × k.

[0090] The voltage (V) is 0.6V, the spacing (L) is 0.2cm, and the area (S) is 12cm². 2 The field density (P) is 2Vcm⁻¹, and the correction factor (k) is 0.5.

[0091] The applied electric field starts synchronously with the battery discharge. If the battery rest time is less than 10 hours, the applied electric field continues to be applied during the rest period. If the battery rest time is more than 10 hours, the applied electric field is applied for 2 hours before the next battery discharge.

[0092] Stop applying the external electric field when the battery power density decays to below 10%.

[0093] Example 5

[0094] This embodiment provides a method for improving the stability of catalysts on the anode and cathode surfaces of a proton exchange membrane fuel cell, the main steps of which are as follows:

[0095] (1) Assembling a proton exchange membrane fuel cell: Refer to Figure 1 and Figure 2 Specifically, the battery consists of a membrane electrode 100, a field electrode 200, and a gas diffusion layer 300, with an assembly pressure of 4 MPa.

[0096] The membrane electrode 100 is composed of a Nafion membrane 101, a cathode platinum-carbon catalyst layer (platinum mass fraction of 20 wt.%) 102, and an anode platinum-carbon catalyst layer (platinum mass fraction of 20 wt.%) 103;

[0097] The field electrode 200 is composed of a controllable DC power supply 201, a cathode field electrode 202, and an anode field electrode 203; both the cathode field electrode 202 and the anode field electrode 203 are composed of copper foil 2021 and insulating rubber pad 2022.

[0098] The membrane electrode 100 and the gas diffusion layer (carbon paper) 300 are placed at the center of the cathode field electrode 202 and the anode field electrode 203. The cathode platinum carbon catalyst layer 102 and the cathode field electrode 202 are on the same side. The anode platinum carbon catalyst layer 103 and the anode field electrode 203 are on the same side. The cumulative thickness of the cathode field electrode 202 and the anode field electrode 203 is the same as the cumulative thickness of the membrane electrode 100 and the gas diffusion layer (carbon paper) 300.

[0099] The cathode field electrode 202 is connected to the positive terminal of the controllable DC power supply 201, and the anode field electrode 203 is connected to the negative terminal of the controllable high voltage DC power supply 201.

[0100] (2) Applying an external electric field:

[0101] The voltage of the controllable DC power supply 201 is controlled to apply an external electric field;

[0102] The voltage value V is determined by the field density P of the membrane electrode 100, the area S of the cathode catalyst layer 102, the distance L between the cathode field electrode 202 and the anode field electrode 203, and the correction coefficient k. The relationship is: V = L × S / P × k.

[0103] Among them, the voltage value (V) is 0.6V, the spacing (L) is 0.1cm, the area (S) is 12cm2, the withstand field density (P) is 2V cm-1, and the correction factor (k) is 1;

[0104] The applied electric field starts synchronously with the battery discharge. If the battery rest time is less than 10 hours, the applied electric field will continue to be applied during the rest time. If the battery rest time is more than 10 hours, the applied electric field will be applied for 2 hours before the next battery discharge.

[0105] Stop applying the external electric field when the battery power density decays to below 10%.

[0106] Example 6

[0107] This embodiment provides a method for improving the stability of catalysts on the anode and cathode surfaces of a proton exchange membrane fuel cell, the main steps of which are as follows:

[0108] (1) Assembling a proton exchange membrane fuel cell: Refer to Figure 1 and Figure 2 Specifically, the battery consists of a membrane electrode 100, a field electrode 200, and a gas diffusion layer 300, with an assembly pressure of 4 MPa.

[0109] The membrane electrode 100 is composed of a Nafion membrane 101, a cathode platinum-carbon catalyst layer (platinum mass fraction of 20 wt.%) 102, and an anode platinum-carbon catalyst layer (platinum mass fraction of 20 wt.%) 103;

[0110] The field electrode 200 is composed of a controllable DC power supply 201, a cathode field electrode 202, and an anode field electrode 203; both the cathode field electrode 202 and the anode field electrode 203 are composed of copper foil 2021 and insulating rubber pad 2022.

[0111] The membrane electrode 100 and the gas diffusion layer (carbon paper) 300 are placed at the center of the cathode field electrode 202 and the anode field electrode 203. The cathode platinum carbon catalyst layer 102 and the cathode field electrode 202 are on the same side. The anode platinum carbon catalyst layer 103 and the anode field electrode 203 are on the same side. The cumulative thickness of the cathode field electrode 202 and the anode field electrode 203 is the same as the cumulative thickness of the membrane electrode 100 and the gas diffusion layer (carbon paper) 300.

[0112] The cathode field electrode 202 is connected to the positive terminal of the controllable DC power supply 201, and the anode field electrode 203 is connected to the negative terminal of the controllable high voltage DC power supply 201.

[0113] (2) Applying an external electric field:

[0114] The voltage of the controllable DC power supply 201 is controlled to apply an external electric field;

[0115] The voltage value V is determined by the field density P of the membrane electrode 100, the area S of the cathode catalyst layer 102, the distance L between the cathode field electrode 202 and the anode field electrode 203, and the correction coefficient k. The relationship is: V = L × S / P × k.

[0116] The voltage (V) is 2.4V, the spacing (L) is 0.1cm, and the area (S) is 6cm². 2 The withstand field density (P) is 2Vcm. -1The correction factor (k) is 0.5;

[0117] The applied electric field starts synchronously with the battery discharge. If the battery rest time is less than 10 hours, the applied electric field will continue to be applied during the rest time. If the battery rest time is more than 10 hours, the applied electric field will be applied for 2 hours before the next battery discharge.

[0118] Stop applying the external electric field when the battery power density decays to below 10%.

[0119] Example 7

[0120] This embodiment provides a method for improving the stability of catalysts on the anode and cathode surfaces of a proton exchange membrane fuel cell, the main steps of which are as follows:

[0121] (1) Assembling a proton exchange membrane fuel cell: Refer to Figure 1 and Figure 2 Specifically, the battery consists of a membrane electrode 100, a field electrode 200, and a gas diffusion layer 300, with an assembly pressure of 4 MPa.

[0122] The membrane electrode 100 is composed of a Nafion membrane 101, a cathode platinum-carbon catalyst layer (platinum mass fraction of 20 wt.%) 102, and an anode platinum-carbon catalyst layer (platinum mass fraction of 20 wt.%) 103;

[0123] The field electrode 200 is composed of a controllable DC power supply 201, a cathode field electrode 202, and an anode field electrode 203; both the cathode field electrode 202 and the anode field electrode 203 are composed of copper foil 2021 and insulating rubber pad 2022.

[0124] The membrane electrode 100 and the gas diffusion layer (carbon paper) 300 are placed at the center of the cathode field electrode 202 and the anode field electrode 203. The cathode platinum carbon catalyst layer 102 and the cathode field electrode 202 are on the same side. The anode platinum carbon catalyst layer 103 and the anode field electrode 203 are on the same side. The cumulative thickness of the cathode field electrode 202 and the anode field electrode 203 is the same as the cumulative thickness of the membrane electrode 100 and the gas diffusion layer (carbon paper) 300.

[0125] The cathode field electrode 202 is connected to the positive terminal of the controllable DC power supply 201, and the anode field electrode 203 is connected to the negative terminal of the controllable high voltage DC power supply 201.

[0126] (2) Applying an external electric field:

[0127] The voltage of the controllable DC power supply 201 is controlled to apply an external electric field;

[0128] The voltage value V is determined by the field density P of the membrane electrode 100, the area S of the cathode catalyst layer 102, the distance L between the cathode field electrode 202 and the anode field electrode 203, and the correction coefficient k. The relationship is: V = L × S / P × k.

[0129] Among them, the voltage value (V) is 0.6V, the spacing (L) is 0.1cm, the area (S) is 12cm2, the withstand field density (P) is 1Vcm-1, and the correction factor (k) is 0.5;

[0130] The applied electric field starts synchronously with the battery discharge. If the battery rest time is less than 10 hours, the applied electric field will continue to be applied during the rest time. If the battery rest time is more than 10 hours, the applied electric field will be applied for 2 hours before the next battery discharge.

[0131] Stop applying the external electric field when the battery power density decays to below 10%.

[0132] In a proton exchange membrane fuel cell, the temperature was 60℃, the gas was H2 / O2 (300 / 150ccm), and the discharge voltage was 0.4V. The initial open-circuit voltage of the battery was 1V. As the discharge progressed, the battery was considered damaged when the open-circuit voltage reached 0.2V. The test results are shown in Table 1.

[0133] Table 1 Cycle life of different embodiments

[0134]

[0135] Comparing Examples 1-3, it can be found that the assembly pressure affects the effect of the applied electric field. This is mainly because the assembly pressure is related to the degree of contact between the membrane electrode 100, the field electrode 200 and the gas diffusion layer 300. Under the same electric field distribution, the degree of contact between the components directly affects the distribution and directionality of the electric field force.

[0136] In addition, the spacing of the applied electric field (Examples 1 and 4), the correction coefficient (Examples 1 and 5), the area (Examples 1 and 6), and the withstand field density (Examples 1 and 7) all affect the electric field distribution and weaken the beneficial effects of the applied electric field.

[0137] Example 8

[0138] Previous research has revealed for the first time that "applying an external electric field in the same direction as the internal electric field of the battery can improve the stability of the catalysts on the cathode and anode surfaces and improve the lifespan of proton exchange membrane fuel cells," as detailed below:

[0139] (1) Experimental materials: commercial platinum carbon, carbon black, Nafion solution, ethanol, perchloric acid, high-purity hydrogen, and high-purity oxygen.

[0140] (2) Experimental apparatus or method: 9 mg of commercial platinum carbon, 1 mg of carbon black and 500 μL of Nafion were mixed into 2 mL of ethanol and sonicated for 12 h. 20 μL of the dispersion was dropped onto the surface of the ring disk electrode and allowed to evaporate naturally to obtain the working electrode.

[0141] A three-electrode system consisting of a working electrode, a graphite ring counter electrode, an Ag / AgCl reference electrode, 0.1M perchloric acid, and high-purity gas (oxygen in the oxygen reduction test and hydrogen in the hydrogen oxidation test) is placed in a cylindrical container. Two copper rings are placed around the outer layer of the container as external electric field application electrodes, and the external electric field application electrodes are connected to a regulated power supply.

[0142] In the oxygen reduction test (after assembling the three electrodes, a negative scan is performed, i.e., a linear scan test from 1.2V to -0.2V), since the direction of the internal electric field is from the working electrode to the counter electrode, an external electric field is simultaneously applied from the working electrode to the counter electrode.

[0143] Similarly, in the hydroxide test (after assembling the three electrodes, a forward scan is performed, i.e., a linear scan test from -0.3V to 0.6V), since the direction of the internal electric field is from the counter electrode to the working electrode, an external electric field is simultaneously applied from the counter electrode to the working electrode.

[0144] (3) Electrochemical testing conditions: Before the linear scan, high-purity gas was bubbled into 0.1M perchloric acid for 30 min at a flow rate of 300 ccm. The scan rate during the linear scan was 5 mV / s. -1 During the test, the rotating speed of the ring electrode was 1600 rpm and the gas flow rate was 50 ccm.

[0145] Figure 3 The results of linear sweep spectroscopy (LSS) tests on the oxygen reduction of the catalyst at different cycling stages show that, after applying an external electric field in the same direction, the limiting current density and half-wave potential decay rate are much slower than those after applying the field in the opposite direction, indicating that the catalyst has stronger stability. Similarly, Figure 4 The linear scan results of the catalyst at different cycling stages show that the limiting current density exhibits the same variation pattern, indicating that the applied electric field has a significant impact on catalyst stability. The linear scan method for assessing catalyst stability is widely accepted in the field.

[0146] It can be seen that after applying an external electric field to the cathode, the decay rates of the cathode half-wave potential and limiting current changed under different electric field environments. The same phenomenon also occurred at the anode, indicating that the external electric field can regulate the electrode reaction process and extend the battery life.

[0147] This invention discloses a method for preparing a proton exchange membrane fuel cell with an applied electric field, addressing the following technical problems: First, it determines that the direction of the applied electric field should be the same as the direction of the internal electric field of the fuel cell; second, it determines the method and control steps for applying the applied electric field; finally, it determines the activation steps for the fuel cell with the applied electric field. Compared with existing technologies, this invention proposes for the first time a technical solution to improve catalyst stability using an applied electric field.

[0148] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for improving the stability of catalysts on the anode and cathode surfaces of a proton exchange membrane fuel cell, characterized in that: include, Applying an external electric field in the same direction as the internal electric field of a proton exchange membrane fuel cell can improve the stability of the catalysts on the cathode and anode surfaces inside the cell. The proton exchange membrane fuel cell consists of a membrane electrode (100), a field electrode (200), and a gas diffusion layer (300), with an assembly pressure of 4 MPa. The membrane electrode (100) is composed of a Nafion membrane (101), a cathode platinum-carbon catalyst layer (102), and an anode platinum-carbon catalyst layer (103), wherein the mass fraction of platinum in the cathode platinum-carbon catalyst layer is 20 wt.%, and the mass fraction of platinum in the anode platinum-carbon catalyst layer is 20 wt.%. The field electrode (200) is composed of a controllable DC power supply (201), a cathode field electrode (202), and an anode field electrode (203); both the cathode field electrode (202) and the anode field electrode (203) are composed of copper foil (2021) and an insulating rubber pad (2022); The membrane electrode (100) and the gas diffusion layer (300) are placed at the center of the cathode field electrode (202) and the anode field electrode (203). The cathode platinum carbon catalyst layer (102) and the cathode field electrode (202) are on the same side. The anode platinum carbon catalyst layer (103) and the anode field electrode (203) are on the same side. The cumulative thickness of the cathode field electrode (202) and the anode field electrode (203) is the same as the cumulative thickness of the membrane electrode (100) and the gas diffusion layer (300). The gas diffusion layer (300) is carbon paper. The cathode field electrode (202) is connected to the positive terminal of the controllable DC power supply (201), and the anode field electrode (203) is connected to the negative terminal of the controllable high voltage DC power supply (201). An external electric field is applied by controlling the voltage of the controllable DC power supply (201); Among them, the field density P of the membrane electrode (100) is 2 V cm⁻¹. -1 The area S of the cathode platinum-carbon catalyst layer (102) is 12 cm². 2 The distance L between the cathode field electrode (202) and the anode field electrode (203) is 0.1 cm, and the voltage value V is 1.2 V; The application of the external electric field begins synchronously with the battery discharge. If the battery rest time is less than 10 hours, the external electric field continues to be applied during the rest period. If the battery rest time is greater than 10 hours, the external electric field is applied for 2 hours before the next battery discharge. Stop applying the external electric field when the battery power density decays to below 10%.

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