Electrolyzed water porous diffusion layer and preparation method and application thereof

Abstract

The invention relates to the field of water electrolysis hydrogen production, in particular to a water electrolysis porous diffusion layer and a preparation method and application thereof. The electrolyzed water porous diffusion layer comprises a microporous layer and a base material layer, the average pore size of the electrolyzed water porous diffusion layer is 10-100 [mu] m, and the thickness of the electrolyzed water porous diffusion layer is 200-500 [mu] m; wherein the average pore diameter of the microporous layer is 0.5-20 [mu] m, and the thickness of the microporous layer is 10-300 [mu] m; the material for preparing the microporous layer comprises titanium powder, and the base material layer comprises a titanium fiber felt. By arranging the microporous layer, the contact resistance of the catalyst layer and the diffusion layer is reduced, and the electrochemical performance is improved; the micropore diameter is regulated and controlled by adjusting the proportion of the two pore-forming agents with different decomposition temperatures, and the obtained electrolyzed water porous diffusion layer can improve the performance of an electrolytic bath and reduce the damage of a proton exchange membrane under high pressure, so that the service life of the proton exchange membrane and an electrode is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of hydrogen production by electrolysis of water, and particularly to a porous diffusion layer for electrolysis of water, a preparation method thereof, and an application thereof. Background Art

[0002] A proton exchange membrane electrolyzer (PEMWE) mainly consists of a membrane electrode composed of a proton exchange membrane, a catalyst, and a porous diffusion layer, bipolar plates, sealing rings, protective sheets, end plates, etc. The core component of the PEM electrolyzer is the membrane electrode (MEA), which is composed of a proton exchange membrane, an anode and a cathode catalyst layer, and a diffusion layer. The role of the diffusion layer is to transport the gas / liquid two-phase from the bipolar plate flow field to the catalyst layer, and at the same time conduct and collect electrons as a current collector. Due to the high anodic overpotential of PEM electrolysis of water, commercial electrolyzers usually use titanium-based porous materials as the anode diffusion layer. To prevent titanium from being oxidized during long-term operation, a platinum or iridium coating needs to be applied on the surface. The pore size and pore structure of the diffusion layer will significantly affect the gas-liquid two-phase transport, thereby affecting the performance of the electrolyzer.

[0003] CN 113957470 B discloses a porous diffusion layer, a preparation method thereof, and a proton exchange membrane electrolysis water hydrogen production device. The porous diffusion layer includes at least two sub-diffusion layers arranged in a stacked manner, namely a first sub-diffusion layer, a second sub-diffusion layer,... a Nth sub-diffusion layer. When the porous diffusion layer includes two sub-diffusion layers, the Nth sub-diffusion layer is the second sub-diffusion layer; and along the direction from the first sub-diffusion layer to the Nth sub-diffusion layer, the porosity, pore size, and thickness of the at least two sub-diffusion layers gradually decrease; the at least two sub-diffusion layers are all hydrophilic. The porous diffusion layer of this patent can withstand high pressure, support and protect the proton exchange membrane, and has hydrophilicity, making water easy to pass through, and is suitable for high-pressure electrolysis of water. However, due to its loose sintering method, the pore size control uniformity of the obtained porous diffusion layer is poor.

[0004] CN115852409A discloses a PEM water electrolysis anode diffusion layer, including a porous layer and a microporous layer. The porous layer is a titanium dioxide nanofiber support layer, which is prepared by hot pressing and calcining at least two layers of titanium nanofiber layers. A microporous layer is prepared on the surface of the titanium dioxide nanofiber support layer, and the microporous layer includes platinum black, spherical dehydrogenated titanium powder, and a binder. The preparation process flow of this PEM water electrolysis anode diffusion layer is complex, and the cost is high due to the addition of precious metal platinum.

[0005] Since the porous diffusion layer anodes in existing PEM electrolytic water hydrogen production mostly use titanium felts, which have relatively large pores, under the high PEM pressure difference, the anode membrane electrode is easily pressed into the holes, affecting performance; at the same time, the diffusion layer with large holes is prone to uneven current distribution, affecting the life of the membrane electrode. In addition, the pore shapes on the surface of the titanium felt material are irregular, and the contact resistance with the catalytic layer is relatively large, easily resulting in relatively high energy consumption of the electrolytic cell. Summary of the Invention

[0006] In view of this, the present invention provides a porous diffusion layer for electrolytic water, its preparation method and application, aiming to improve the performance of the electrolytic cell and reduce the damage to the proton exchange membrane under high pressure, thereby improving the life of the proton exchange membrane and the electrode.

[0007] To achieve the above object, the present invention adopts the following technical solutions.

[0008] According to the first aspect of the present invention, there is provided a porous diffusion layer for electrolytic water, the porous diffusion layer for electrolytic water includes a microporous layer and a substrate layer, and the average pore diameter of the porous diffusion layer for electrolytic water is 10 - 100 μm; wherein, the average pore diameter of the microporous layer is 0.5 - 20 μm.

[0009] For the above-mentioned porous diffusion layer for electrolytic water, the thickness of the microporous layer of the microporous layer is 10 - 300 μm.

[0010] For the above-mentioned porous diffusion layer for electrolytic water, the thickness of the porous diffusion layer for electrolytic water is 200 - 500 μm.

[0011] For the above-mentioned porous diffusion layer for electrolytic water, the material for preparing the microporous layer includes titanium powder.

[0012] For the above-mentioned porous diffusion layer for electrolytic water, the substrate layer includes a titanium fiber felt.

[0013] According to the second aspect of the present invention, there is provided a preparation method for the above-mentioned porous diffusion layer for electrolytic water, including the following steps:

[0014] 1) Mix titanium powder and a pore-forming agent to obtain a mixed powder, and press the mixed powder to obtain a blank;

[0015] 2) Pre-sinter the blank to obtain a microporous layer;

[0016] 3) Secondarily press the microporous layer and the substrate layer to obtain a composite diffusion layer;

[0017] 4) Secondarily sinter the composite diffusion layer to obtain a diffusion layer with a microporous layer, that is, the porous diffusion layer for electrolytic water.

[0018] In the above preparation method, in step 1), the titanium powder and the pore-forming agent are mixed in a mass ratio of 1:0.05 - 0.3.

[0019] By controlling the mass ratio of the titanium powder and the pore former, the present invention is conducive to controlling the strength of the porous diffusion layer for electrolyzed water. If the mass ratio of the titanium powder and the pore former is too high, the pore-forming effect will be affected and the pore-forming efficiency will be reduced; if the mass ratio is too low, the strength of the porous diffusion layer for electrolyzed water will be affected.

[0020] In the above preparation method, in step 1), the titanium powder includes titanium metal powder.

[0021] In the above preparation method, in step 1), the particle size range of the titanium metal powder is 200 - 500 mesh.

[0022] In the above preparation method, in step 1), the pore former includes urea and ammonium bicarbonate.

[0023] In the above preparation method, in step 1), in the pore former, the mass ratio of urea and ammonium bicarbonate is 1:0.15 - 0.7.

[0024] In the present invention, urea and ammonium bicarbonate have different decomposition temperatures. Therefore, at different sintering temperatures, the two pore formers decompose to form micropores respectively. The pore former with a lower decomposition temperature decomposes to form micropores at a relatively lower heating temperature, and the pore former with a higher decomposition temperature decomposes to form micropores at a higher heating temperature on the basis of the micropores formed by the pore former with a lower decomposition temperature, thereby forming micropores with different pore diameters. Therefore, by adjusting the ratio of the two pore formers (urea and ammonium bicarbonate) with different decomposition temperatures, the present invention can control the micropore diameter of the porous diffusion layer for electrolyzed water.

[0025] In the above preparation method, in step 1), the mixing includes any one of ball milling mixing, shear stirring mixing, and screw mixing.

[0026] In the above preparation method, in step 1), the mixing time is 2 - 96 h.

[0027] In the above preparation method, in step 1), the pressure of the pressing is 50 - 250 MPa.

[0028] In the above preparation method, in step 1), the thickness of the microporous layer of the green compact obtained by pressing is 10 - 300 μm.

[0029] In the above preparation method, in step 2), the temperature of the pre-sintering is 700 - 900 °C.

[0030] In the above preparation method, in step 2), the pre-sintering process adopts a programmed heating mode, including three heat preservation platforms, and then cools to room temperature; among them, the first temperature platform is 150-200°C, the heating rate is 1-4°C / min, and the heat preservation time is 2-8 h; the second temperature platform is 300-500°C, the heating rate is 1-4°C / min, and the heat preservation time is 0.5-4 h; the third temperature platform is 700-900°C, the heating rate is 4-10°C / min, and the heat preservation time is 1-4 h.

[0031] By controlling the heating rate during pre-sintering, the present invention can adjust the biochemical rates of the two pore-forming agents, so that the pore-forming agents decompose uniformly at the decomposition temperature to form micropores, thereby making the electrolytic water porous diffusion layer have uniform micropores.

[0032] In the above preparation method, the pre-sintering is carried out in a vacuum environment.

[0033] In the above preparation method, in step 2), the thickness of the microporous layer of the microporous layer is 10-300 μm, and the average pore diameter is 0.5-20 μm.

[0034] In the above preparation method, in step 3), the substrate layer includes a titanium fiber felt.

[0035] In the above preparation method, in step 3), the pressure of the secondary pressing is 60-180 MPa.

[0036] In the above preparation method, in step 3), the thickness of the composite diffusion layer is 200-500 μm, and the average pore diameter is 10-100 μm.

[0037] In the above preparation method, in step 4), the temperature of the secondary sintering is 900-1300°C, and the heat preservation time is 1-4 h.

[0038] In the present invention, if the temperature of the secondary sintering is too low, it is easy to reduce the strength of the substrate; if the temperature of the secondary sintering is too high, it is easy to cause uneven pore size distribution of the microporous layer, thereby affecting the performance of the electrolytic water porous diffusion layer. Therefore, by controlling the temperature of the secondary sintering, the present invention makes the pore diameter of the microporous layer formed by the electrolytic water porous diffusion layer evenly distributed while strengthening the strength of the substrate, and improves the performance of the electrolytic water porous diffusion layer.

[0039] In the above preparation method, in step 4), the heating rate of the secondary sintering is 4-10°C / min.

[0040] According to the third aspect of the present invention, there is provided an application of the above electrolytic water porous diffusion layer as an anode gas diffusion layer in a proton exchange membrane electrolytic water hydrogen production device in the field of electrolytic water hydrogen production.

[0041] In the above application, the proton exchange membrane electrolytic water hydrogen production device includes an anode gas diffusion layer, an anode flow field plate, and a membrane electrode. The anode gas diffusion layer uses the above-mentioned electrolytic water porous diffusion layer. The microporous layer of the electrolytic water porous diffusion layer is in contact with the anode catalytic layer of the membrane electrode, and the substrate layer of the electrolytic water porous diffusion layer is in contact with the anode flow field plate.

[0042] In the above application, when the electrolytic water porous diffusion layer is used as the anode gas diffusion layer in the proton exchange membrane electrolytic water hydrogen production device in the field of electrolytic water hydrogen production, at a current density of 2 A / cm 2 , when the voltage is 1.84 V, the contact resistance between the electrolytic water anode catalytic layer and the electrolytic water porous diffusion layer can be reduced to 15.2 mΩ·cm 2 .

[0043] In the present invention, without conflict, the above technical features can be freely combined to form new technical solutions.

[0044] The above technical solutions provided by the present invention have the following beneficial technical effects compared with the prior art:

[0045] (1) According to the technical solution of the present invention, by providing a microporous layer in the electrolytic water porous diffusion layer, the contact resistance between the electrolytic water anode catalytic layer and the electrolytic water porous diffusion layer is reduced, and the electrochemical performance is improved;

[0046] (2) According to the technical solution of the present invention, by adjusting the ratio of pore-forming agents with two different decomposition temperatures, the micropore diameter can be controlled, so as to realize the free control of the micropore diameter of the microporous layer in the electrolytic water porous diffusion layer;

[0047] (3) According to the technical solution of the present invention, by controlling the heating rate during pre-sintering to adjust the biochemical rate of the pore-forming agent, the micropores formed in the electrolytic water porous diffusion layer are made uniform, thereby reducing the contact resistance between the electrolytic water anode catalytic layer and the diffusion layer and improving the electrochemical performance;

[0048] (4) According to the technical solution of the present invention, by controlling the mass ratio of titanium powder and pore-forming agent, the strength of the electrolytic water porous diffusion layer is improved, thereby reducing the damage of the proton exchange membrane under high pressure and improving the service life of the proton exchange membrane and the electrode. Specific Embodiments

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0050] According to some embodiments of the first aspect of the present invention, an electrolyzed water porous diffusion layer is provided. The electrolyzed water porous diffusion layer includes a microporous layer and a substrate layer. The average pore diameter of the electrolyzed water porous diffusion layer is 10 - 100 μm (for example, 20 μm, 30 μm, 50 μm, 70 μm, 80 μm or 90 μm); wherein, the average pore diameter of the microporous layer is 0.5 - 20 μm (for example, 1 μm, 2 μm, 5 μm, 10 μm or 15 μm).

[0051] According to some embodiments of the first aspect of the present invention, the thickness of the microporous layer of the microporous layer is 10 - 300 μm (for example, 20 μm, 50 μm, 100 μm, 150 μm, 200 μm or 250 μm).

[0052] According to some embodiments of the first aspect of the present invention, the thickness of the electrolyzed water porous diffusion layer is 200 - 500 μm (for example, 250 μm, 300 μm, 350 μm, 400 μm or 450 μm).

[0053] According to some embodiments of the first aspect of the present invention, the material for preparing the microporous layer includes titanium powder.

[0054] According to some embodiments of the first aspect of the present invention, the substrate layer includes a titanium fiber felt.

[0055] According to some embodiments of the second aspect of the present invention, a method for preparing the above-mentioned electrolyzed water porous diffusion layer is provided, including the following steps:

[0056] A method for preparing the above-mentioned electrolyzed water porous diffusion layer includes the following steps:

[0057] S1. Mix titanium powder and a pore-forming agent to obtain a mixed powder, and press the mixed powder to obtain a blank;

[0058] S2. Pre-sinter the blank to obtain a microporous layer;

[0059] S3. Secondarily press the microporous layer and the substrate layer to obtain a composite diffusion layer;

[0060] S4. Secondarily sinter the composite diffusion layer to obtain a diffusion layer with a microporous layer, that is, the electrolyzed water porous diffusion layer.

[0061] According to some embodiments of the second aspect of the present invention, in step 1), the titanium powder and the pore-forming agent are mixed in a mass ratio of 1:0.05 - 0.3 (for example, 1:0.10, 1:0.15, 1:0.20 or 1:0.25).

[0062] By controlling the mass ratio of the titanium powder and the pore-forming agent in the present invention, it is beneficial to control the strength of the porous diffusion layer for electrolyzed water. If the mass ratio of the titanium powder and the pore-forming agent is too high, the pore-forming effect will be affected. If the mass ratio is too low, the strength of the porous diffusion layer will be affected.

[0063] According to some embodiments of the second aspect of the present invention, in the step 1), the titanium powder includes titanium metal powder.

[0064] According to some embodiments of the second aspect of the present invention, in the step 1), the particle size range of the titanium metal powder is 200 - 500 mesh (for example, 250 mesh, 300 mesh, 350 mesh, 400 mesh or 450 mesh).

[0065] According to some embodiments of the second aspect of the present invention, in the step 1), the pore-forming agent includes urea and ammonium bicarbonate.

[0066] According to some embodiments of the second aspect of the present invention, in the step 1), in the pore-forming agent, the mass ratio of urea to ammonium bicarbonate is 1:0.15 - 0.7 (for example, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, or 1:0.65).

[0067] In the present invention, urea and ammonium bicarbonate have different decomposition temperatures. Therefore, at different sintering temperatures, the two pore-forming agents decompose to form micropores respectively. The pore-forming agent with a lower decomposition temperature decomposes to form micropores at a relatively lower heating temperature. The pore-forming agent with a higher decomposition temperature decomposes to form micropores at a higher heating temperature on the basis of the micropores formed by the pore-forming agent with a lower decomposition temperature, thereby forming micropores with different pore diameters. Therefore, by adjusting the ratio of the two pore-forming agents (urea and ammonium bicarbonate) with different decomposition temperatures in the present invention, the micropore diameter of the porous diffusion layer for electrolyzed water can be regulated.

[0068] According to some embodiments of the second aspect of the present invention, in the step 1), the mixing includes any one of ball milling mixing, shear stirring mixing and screw mixing.

[0069] According to some embodiments of the second aspect of the present invention, in the step 1), the mixing time is 2 - 96 h (for example, 5 h, 10 h, 20 h, 30 h, 40 h, 50 h, 60 h, 70 h, 80 h or 90 h).

[0070] According to some embodiments of the second aspect of the present invention, in the step 1), the pressure of the pressing is 50 - 250 MPa (for example, 80 MPa, 100 MPa, 150 MPa, 200 MPa or 230 MPa).

[0071] In some embodiments according to the second aspect of the present invention, in step 1), the thickness of the microporous layer of the blank obtained by pressing is 10 - 300 μm (for example, 20 μm, 50 μm, 100 μm, 150 μm, 200 μm or 250 μm).

[0072] In some embodiments according to the second aspect of the present invention, in step 2), the temperature of the pre-sintering is 700 - 900 °C (for example, 720 °C, 750 °C, 800 °C, 850 °C or 880 °C).

[0073] In some embodiments according to the second aspect of the present invention, in step 2), the pre-sintering process uses program temperature control, including three heat preservation platforms, and then cools to room temperature; wherein, the first temperature platform is 150 - 200 °C (for example, 160 °C, 170 °C, 180 °C or 190 °C), the heating rate is 1 - 4 °C / min (for example, 1.5 °C / min, 2 °C / min, 3 °C / min or 3.5 °C / min), and the heat preservation time is 2 - 8 h (for example, 3 h, 4 h, 5 h, 6 h or 7 h); the second temperature platform is 300 - 500 °C (for example, 320 °C, 350 °C, 400 °C, 450 °C or 480 °C), the heating rate is 1 - 4 °C / min (for example, 1.5 °C / min, 2 °C / min, 3 °C / min or 3.5 °C / min), and the heat preservation time is 0.5 - 4 h (for example, 1 h, 1.5 h, 2 h, 3 h or 3.5 h); the third temperature platform is 700 - 900 °C (for example, 720 °C, 750 °C, 800 °C, 850 °C or 880 °C), the heating rate is 4 - 10 °C / min (for example, 5 °C / min, 6 °C / min, 7 °C / min or 9 °C / min), and the heat preservation time is 1 - 4 h (for example, 1 h, 1.5 h, 2 h, 3 h or 3.5 h).

[0074] By controlling the heating rate during pre-sintering, the present invention can adjust the biochemical rates of the two pore-forming agents, so that the pore-forming agents decompose uniformly at the decomposition temperature to form micropores, thereby making the electrolyzed water porous diffusion layer have uniform micropores.

[0075] In some embodiments according to the second aspect of the present invention, the pre-sintering is carried out in a vacuum environment.

[0076] In some embodiments according to the second aspect of the present invention, in step 2), the thickness of the microporous layer of the microporous layer is 10 - 300 μm (for example, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm or 280 μm), and the average pore diameter is 0.5 - 20 μm (for example, 1 μm, 2 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm or 18 μm).

[0077] In some embodiments of the second aspect of the present invention, in step 3), the substrate layer includes a titanium fiber felt.

[0078] In some embodiments of the second aspect of the present invention, in step 3), the pressure of the secondary pressing is 60 - 180 MPa (for example, 70 MPa, 80 MPa, 100 MPa, 120 MPa or 150 MPa).

[0079] In some embodiments of the second aspect of the present invention, in step 3), the thickness of the composite diffusion layer is 200 - 500 μm (for example, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm or 480 μm), and the average pore diameter is 10 - 100 μm (for example, 20 μm, 30 μm, 50 μm, 60 μm, 70 μm or 80 μm).

[0080] In some embodiments of the second aspect of the present invention, in step 4), the temperature of the secondary sintering is 900 - 1300 °C (for example, 950 °C, 1000 °C, 1100 °C, 1200 °C or 1250 °C), and the heat preservation time is 1 - 4 h (for example, 1 h, 1.5 h, 2 h, 3 h or 3.5 h).

[0081] In the present invention, if the temperature of the secondary sintering is too low, it is easy to reduce the strength of the substrate; if the temperature of the secondary sintering is too high, it is easy to cause uneven pore size distribution of the microporous layer, thus affecting the performance of the electrolyzed water porous diffusion layer. Therefore, by controlling the temperature of the secondary sintering, the present invention makes the pore size of the microporous layer formed by the electrolyzed water porous diffusion layer evenly distributed while strengthening the strength of the substrate, and improves the performance of the electrolyzed water porous diffusion layer.

[0082] In some embodiments of the second aspect of the present invention, in step 4), the heating rate of the secondary sintering is 4 - 10 °C / min (for example, 5 °C / min, 6 °C / min, 7 °C / min or 9 °C / min).

[0083] In some embodiments of the third aspect of the present invention, there is provided an application of the above-mentioned electrolyzed water porous diffusion layer as an anode gas diffusion layer in a proton exchange membrane electrolyzed water hydrogen production device in the field of electrolyzed water hydrogen production.

[0084] In some embodiments of the third aspect of the present invention, the proton exchange membrane electrolyzed water hydrogen production device includes an anode gas diffusion layer, an anode flow field plate and a membrane electrode. The anode gas diffusion layer adopts the above-mentioned electrolyzed water porous diffusion layer. The microporous layer of the electrolyzed water porous diffusion layer is in contact with the anode catalytic layer of the membrane electrode, and the substrate layer of the electrolyzed water porous diffusion layer is in contact with the anode flow field plate.

[0085] According to some embodiments of the third aspect of the present invention, when the electrolyzed water porous diffusion layer is applied in the field of electrolyzed water hydrogen production as the anode gas diffusion layer in a proton exchange membrane electrolyzed water hydrogen production device, at a current density of 2 A / cm 2 2, when the voltage is 1.84 V, the contact resistance between the electrolyzed water anode catalyst layer and the electrolyzed water porous diffusion layer can be reduced to 15.2 mΩ·cm 2 .

[0086] Example 1

[0087] A preparation method of an electrolyzed water porous diffusion layer includes the following steps:

[0088] S1. Mix titanium powder with a pore-forming agent to obtain a mixed powder, and press the mixed powder to obtain a blank; specifically, take 250-mesh titanium metal powder and pore-forming agent powder in a mass ratio of 1:0.1, mix them by a ball mill for 48 h, the pore-forming agent consists of ammonium bicarbonate and urea, and the mass ratio of urea to ammonium bicarbonate is 1:0.5; press the mixed powder into a blank by a press, the pressing pressure is 160 MPa, and the pressing thickness is 150 μm;

[0089] S2. Put the blank into a vacuum sintering furnace for pre-sintering to obtain a microporous layer; among them, set the programmed heating parameters: the first temperature platform is 150 °C, the heating rate is 2 °C / min, and the heat preservation time is 2 h; the second temperature platform is 380 °C, the heating rate is 4 °C / min, and the heat preservation time is 2 h; the third temperature platform is 800 °C, the heating rate is 6 °C / min, and the heat preservation time is 2 h; then cool to room temperature;

[0090] S3. Perform secondary pressing on the microporous layer and the substrate layer to obtain a composite diffusion layer; among them, the secondary pressing pressure is 100 MPa, the substrate layer is a titanium fiber felt, the thickness is 400 μm, and the average pore diameter is 20 μm;

[0091] S4. Perform secondary sintering on the composite diffusion layer to obtain a diffusion layer with a microporous layer, that is, the electrolyzed water porous diffusion layer; among them, the secondary sintering temperature is 1100 °C, the heating rate is 6 °C / min, and the heat preservation time is 2 h.

[0092] The electrolyzed water porous diffusion layer prepared in this example has a thickness of 400 μm and an average pore diameter of 20 μm.

[0093] Assemble the electrolyzed water porous diffusion layer prepared in this example into an electrolytic cell, and test the polarization curve and contact resistance. The results show that at a current density of 2 A / cm 2 2, when the voltage is 1.84 V, the contact resistance between the electrolyzed water anode catalyst layer and the electrolyzed water porous diffusion layer in this electrolytic cell is 15.2 mΩ·cm 2 .

[0094] Example 2

[0095] A preparation method of an electrolyzed water porous diffusion layer, comprising the following steps:

[0096] S1. Mix titanium powder with a pore-forming agent to obtain a mixed powder, and press the mixed powder to obtain a blank; specifically, take 400-mesh titanium metal powder and pore-forming agent powder in a mass ratio of 1:0.25 and mix them in a ball mill for 72 h. The pore-forming agent consists of ammonium bicarbonate and urea, and the mass ratio of urea to ammonium bicarbonate is 1:0.3. The mixed powder is pressed into a blank by a press, the pressing pressure is 200 MPa, and the pressing thickness is 80 μm;

[0097] S2. Put the blank into a vacuum sintering furnace for pre-sintering to obtain a microporous layer; among them, set the programmed heating parameters: the first temperature platform is 170 °C, the heating rate is 2 °C / min, and the heat preservation time is 2 h; the second temperature platform is 450 °C, the heating rate is 3 °C / min, and the heat preservation time is 2 h; the third temperature platform is 900 °C, the heating rate is 9 °C / min, and the heat preservation time is 1.5 h; then cool to room temperature.

[0098] S3. Perform secondary pressing on the microporous layer and the substrate layer to obtain a composite diffusion layer; among them, the secondary pressing pressure is 80 MPa; the substrate layer is a titanium fiber felt with a thickness of 300 μm and an average pore diameter of 40 μm;

[0099] S4. Perform secondary sintering on the composite diffusion layer to obtain a diffusion layer with a microporous layer, that is, the electrolyzed water porous diffusion layer; among them, the secondary sintering temperature is 1000 °C, the heating rate is 4 °C / min, and the heat preservation time is 4 h.

[0100] The electrolyzed water porous diffusion layer prepared in this example has a thickness of 300 μm and an average pore diameter of 40 μm.

[0101] Use the method in Example 1 to assemble the electrolyzed water porous diffusion layer prepared in this example into an electrolytic cell, and test the polarization curve and contact resistance. The results show that at a current density of 2 A / cm 2 ², when the voltage is 1.89 V, the contact resistance between the electrolyzed water anode catalyst layer and the electrolyzed water porous diffusion layer in this electrolytic cell is 16.5 mΩ·cm 2 .

[0102] Comparative Example 1

[0103] A preparation method of an electrolyzed water porous diffusion layer, comprising the following steps:

[0104] S1. Take 250-mesh titanium metal powder and press it into a blank by a press, the pressing pressure is 160 MPa, and the pressing thickness is 150 μm;

[0105] S2. Place the blank in a vacuum sintering furnace for pre-sintering to obtain a microporous layer. Among them, set the programmed heating parameters: the first temperature platform is 150 °C, the heating rate is 2 °C / min, and the holding time is 2 h; the second temperature platform is 380 °C, the heating rate is 4 °C / min, and the holding time is 2 h; the third temperature platform is 800 °C, the heating rate is 6 °C / min, and the holding time is 2 h; then cool to room temperature.

[0106] S3. Perform secondary pressing on the microporous layer and the substrate layer to obtain a composite diffusion layer. Among them, the secondary pressing pressure is 100 MPa, the substrate layer is a titanium fiber felt, with a thickness of 400 μm and an average pore diameter of 20 μm.

[0107] S4. Perform secondary sintering on the composite diffusion layer to obtain a diffusion layer with a microporous layer, that is, the electrolyzed water porous diffusion layer. Among them, the secondary sintering temperature is 1100 °C, the heating rate is 6 °C / min, and the holding time is 2 h.

[0108] The electrolyzed water porous diffusion layer prepared in this comparative example has a thickness of 400 μm and an average pore diameter of 20 μm.

[0109] Use the method in Example 1 to assemble the electrolyzed water porous diffusion layer prepared in this comparative example into an electrolytic cell, and test the polarization curve and contact resistance. The results show that at a current density of 2 A / cm 2 When the voltage is 1.97 V, the contact resistance between the electrolyzed water anode catalyst layer and the electrolyzed water porous diffusion layer in this electrolytic cell is 18.8 mΩ·cm 2 .

[0110] Compared with the performance of the electrolytic cells assembled with the electrolyzed water porous diffusion layers prepared in Examples 1 and 2, since no pore-forming agent was added during the preparation process of the electrolyzed water porous diffusion layer prepared in this comparative example, there is no microporous layer in the prepared electrolyzed water porous diffusion layer. Therefore, the contact resistance in the electrolytic cell prepared with the electrolyzed water porous diffusion layer in this comparative example is significantly higher than that in the electrolytic cells in Examples 1 and 2.

[0111] Comparative Example 2

[0112] A preparation method of an electrolyzed water porous diffusion layer includes the following steps:

[0113] S1. Mix titanium powder and a pore-forming agent to obtain a mixed powder, and press the mixed powder to obtain a blank. Specifically, take 250-mesh titanium metal powder and a pore-forming agent powder in a mass ratio of 1:0.1 and mix them in a ball mill for 48 h. The pore-forming agent is urea; the mixed powder is pressed into a blank by a press, the pressing pressure is 160 MPa, and the pressing thickness is 150 μm.

[0114] S2. Place the blank in a vacuum sintering furnace for pre-sintering to obtain a microporous layer. Specifically, set the programmed heating parameters: the first temperature platform is 150 °C, the heating rate is 2 °C / min, and the holding time is 2 h; the second temperature platform is 380 °C, the heating rate is 4 °C / min, and the holding time is 2 h; the third temperature platform is 800 °C, the heating rate is 6 °C / min, and the holding time is 2 h; then cool to room temperature.

[0115] S3. Perform secondary pressing on the microporous layer and the substrate layer to obtain a composite diffusion layer. Specifically, the secondary pressing pressure is 100 MPa, the substrate layer is a titanium fiber felt with a thickness of 400 μm and an average pore diameter of 20 μm.

[0116] S4. Perform secondary sintering on the composite diffusion layer to obtain a diffusion layer with a microporous layer, that is, the electrolyzed water porous diffusion layer. Specifically, the secondary sintering temperature is 1100 °C, the heating rate is 6 °C / min, and the holding time is 2 h.

[0117] The electrolyzed water porous diffusion layer prepared in this comparative example has a thickness of 400 μm and an average pore diameter of 20 μm.

[0118] Use the electrolytic cell assembly method in Example 1 to assemble the porous diffusion layer prepared in this comparative example into an electrolytic cell, and use the electrochemical performance test method in Example 1 to test the polarization curve and contact resistance of the electrolytic cell. The results show that since only urea is used as a pore-forming agent in the process of preparing the electrolyzed water porous diffusion layer in this comparative example, the micropores in the microporous layer obtained during the pre-sintering of the formed blank are uneven, and the pore diameter cannot be freely adjusted. Therefore, the performance of the finally formed electrolyzed water porous diffusion layer is poorer than that of the electrolyzed water porous diffusion layers obtained by using two pore-forming agents in Examples 1 and 2.

[0119] Comparative Example 3

[0120] A preparation method of an electrolyzed water porous diffusion layer includes the following steps:

[0121] S1. Mix titanium powder with a pore-forming agent to obtain a mixed powder, and press the mixed powder to obtain a blank. Specifically, take 250-mesh titanium metal powder and pore-forming agent powder in a mass ratio of 1:0.1 and mix them by a ball mill for 48 h. The pore-forming agent is ammonium bicarbonate. The mixed powder is pressed into a blank by a press, the pressing pressure is 160 MPa, and the pressing thickness is 150 μm.

[0122] S2. Place the blank in a vacuum sintering furnace for pre-sintering to obtain a microporous layer. Specifically, set the programmed heating parameters: the first temperature platform is 150 °C, the heating rate is 2 °C / min, and the holding time is 2 h; the second temperature platform is 380 °C, the heating rate is 4 °C / min, and the holding time is 2 h; the third temperature platform is 800 °C, the heating rate is 6 °C / min, and the holding time is 2 h; then cool to room temperature.

[0123] S3. Secondarily press the microporous layer and the substrate layer to obtain a composite diffusion layer. Among them, the secondary pressing pressure is 100 MPa, the substrate layer is a titanium fiber felt with a thickness of 400 μm and an average pore diameter of 20 μm.

[0124] S4. Secondarily sinter the composite diffusion layer to obtain a diffusion layer with a microporous layer, that is, the electrolyzed water porous diffusion layer. Among them, the secondary sintering temperature is 1100 °C, the heating rate is 6 °C / min, and the heat preservation time is 2 h.

[0125] The electrolyzed water porous diffusion layer prepared in this comparative example has a thickness of 400 μm and an average pore diameter of 20 μm.

[0126] Use the electrolytic cell assembly method in Example 1 to assemble the porous diffusion layer prepared in this comparative example into an electrolytic cell, and use the electrochemical performance test method in Example 1 to test the polarization curve and contact resistance of the electrolytic cell. The results show that since only ammonium bicarbonate is used as a pore-forming agent in the process of preparing the electrolyzed water porous diffusion layer in this comparative example, the micropores in the microporous layer obtained during the pre-sintering process of the formed green body are uneven, and the pore diameter cannot be freely adjusted. Therefore, the performance of the finally formed electrolyzed water porous diffusion layer is worse than that of the electrolyzed water porous diffusion layers obtained by using two pore-forming agents in Examples 1 and 2.

[0127] Although this specification contains many specific implementation details, these should not be construed as limiting the scope of any invention or the scope of what is claimed, but are mainly used to describe the features of specific embodiments of a particular invention. Certain features described in multiple embodiments in this specification can also be combined and implemented in a single embodiment. On the other hand, various features described in a single embodiment can also be separately implemented in multiple embodiments or implemented in any suitable sub-combination. In addition, although features may function in certain combinations as described above and are even initially claimed as such, one or more features from the claimed combination can in some cases be removed from the combination, and the claimed combination can be directed to a sub-combination or a variant of the sub-combination.

[0128] It should be noted that in this article, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0129] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. The present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. An electrolyzed water porous diffusion layer, characterized in that, The electrolyzed water porous diffusion layer includes a microporous layer and a substrate layer, and the average pore size of the electrolyzed water porous diffusion layer is 10 - 100 μm; wherein, the average pore size of the microporous layer is 0.5 - 20 μm.

2. The electrolyzed water porous diffusion layer according to claim 1, wherein The thickness of the microporous layer of the microporous layer is 10 - 300 μm, and the thickness of the electrolyzed water porous diffusion layer is 200 - 500 μm.

3. The electrolyzed water porous diffusion layer according to claim 1, wherein The material for preparing the microporous layer includes titanium powder, and the substrate layer includes a titanium fiber felt.

4. A method for preparing the electrolyzed water porous diffusion layer according to any one of claims 1-3, characterized in that, The preparation method includes the following steps: 1) Mix titanium powder with a pore-forming agent to obtain a mixed powder, and press the mixed powder to obtain a blank. 2) Pre-sinter the blank to obtain a microporous layer. 3) Secondarily press the microporous layer and the substrate layer to obtain a composite diffusion layer. 4) Secondarily sinter the composite diffusion layer to obtain a diffusion layer with a microporous layer, that is, the electrolyzed water porous diffusion layer.

5. The preparation method of the electrolyzed water porous diffusion layer according to claim 4, characterized in that, In the step 1), the titanium powder and the pore-forming agent are mixed according to a mass ratio of 1:0.05 - 0.

3.

6. The preparation method of the electrolyzed water porous diffusion layer according to claim 4, characterized in that, In the step 1), the titanium powder includes titanium metal powder, and the particle size range of the titanium metal powder is 200 - 500 mesh.

7. The preparation method of the electrolyzed water porous diffusion layer according to claim 4, characterized in that, In the step 1), the pore-forming agent includes urea and ammonium bicarbonate; in the pore-forming agent, the mass ratio of urea to ammonium bicarbonate is 1:0.15 - 0.

7.

8. The preparation method of the electrolyzed water porous diffusion layer according to claim 4, wherein, In the step 1), the mixing includes any one of ball milling mixing, shear stirring mixing, and screw mixing.

9. The preparation method of the electrolyzed water porous diffusion layer according to claim 4, characterized in that, The mixing time is 2 - 96 h.

10. The preparation method of the electrolyzed water porous diffusion layer according to claim 4, wherein In the step 1), the pressure of the pressing is 50 - 250 MPa.

11. The preparation method of the electrolyzed water porous diffusion layer according to claim 4, characterized in that, In the step 1), the thickness of the microporous layer of the obtained blank is 10 - 300 μm.

12. The preparation method of the electrolyzed water porous diffusion layer according to claim 4, wherein In the step 2), the temperature of the pre-sintering is 700 - 900 °C.

13. The preparation method of the electrolyzed water porous diffusion layer according to claim 4, wherein, In the step 2), the pre-sintering process uses program temperature control, including three heat preservation platforms, and then cools to room temperature; wherein, the first temperature platform is 150 - 200 °C, the heating rate is 1 - 4 °C / min, and the heat preservation time is 2 - 8 h; the second temperature platform is 300 - 500 °C, the heating rate is 1 - 4 °C / min, and the heat preservation time is 0.5 - 4 h; the third temperature platform is 700 - 900 °C, the heating rate is 4 - 10 °C / min, and the heat preservation time is 1 - 4 h.

14. The preparation method of the electrolyzed water porous diffusion layer according to claim 4, characterized in that, In the step 2), the pre-sintering is carried out in a vacuum environment.

15. The preparation method of the electrolyzed water porous diffusion layer according to claim 4, wherein In the step 2), the thickness of the microporous layer of the microporous layer is 10 - 300 μm, and the average pore size is 0.5 - 20 μm.

16. The preparation method of the electrolyzed water porous diffusion layer according to claim 4, characterized in that, In the step 3), the pressure of the secondary pressing is 60 - 180 MPa.

17. The preparation method of the electrolyzed water porous diffusion layer according to claim 5, wherein, In the step 3), the thickness of the composite diffusion layer is 200 - 500 μm, and the average pore size is 10 - 100 μm.

18. The preparation method of the electrolyzed water porous diffusion layer according to claim 5, characterized in that, In the step 4), the temperature of the secondary sintering is 900 - 1300 °C, the heating rate is 4 - 10 °C / min, and the heat preservation time is 1 - 4 h.

19. An application of the electrolyzed water porous diffusion layer according to any one of claims 1 - 3 as an anode gas diffusion layer in a proton exchange membrane electrolyzed water hydrogen production device in the field of electrolyzed water hydrogen production.

20. Use of the electrolyzed water porous diffusion layer according to claim 19 as an anode gas diffusion layer in a proton exchange membrane electrolyzed water hydrogen production device in the field of electrolyzed water hydrogen production, characterized in that, The proton exchange membrane electrolytic water hydrogen production device includes an anode gas diffusion layer, an anode flow field plate and a membrane electrode. The anode gas diffusion layer uses the above-mentioned electrolytic water porous diffusion layer. The microporous layer of the electrolytic water porous diffusion layer is in contact with the anode catalyst layer of the membrane electrode, and the substrate layer of the electrolytic water porous diffusion layer is in contact with the anode flow field plate.