CN114959762A - Membrane electrode for solid electrolyte electrolytic cell - Google Patents

Abstract

The invention provides a membrane electrode of a solid electrolyte electrolytic cell, which comprises an optimized layer, wherein the optimized layer can improve the operation efficiency and safety of the electrolytic cell, and is realized by reducing the hydrogen content in an anode. The preparation process of the optimized layer structure is simple and easy to implement, and can be realized through common processes such as spraying, screen printing, blade coating and the like. The position of the assembly of the optimization layer may be between the anode catalytic layer and the membrane, or outside the anode catalytic layer, or mixed with either or both of the anode catalytic layers. The principle is that the optimized layer quenches hydrogen on the anode side through chemical reaction, and the effect of reducing the hydrogen content is achieved. Through optimization of the membrane electrode by the optimization layer, the gas purity and the hydrogen concentration of the anode side of the electrolytic cell are beyond the explosion limit on the basis of not obviously increasing the system cost and auxiliary equipment, and the effects of efficiency improvement and safe operation are achieved.

Description

Membrane electrode for solid electrolyte electrolytic cell

technical field

The invention belongs to the field of solid electrolyte water electrolysis, and in particular relates to a membrane electrode for improving the operation safety and efficiency of a solid electrolyte electrolytic cell.

Background technique

The water electrolysis technology using a solid electrolyte electrolyzer is a green energy storage technology that can directly use renewable energy to generate electricity and electrolyze pure water to produce hydrogen. Insulation, high-pressure operation can be realized on both sides, high-pressure product gas can be obtained online, and the cost of later gas compression can be reduced. However, due to the deviation of the sealing effect in the actual process or the influence of the airtightness of the membrane, especially when the thickness of the membrane is reduced or high-pressure operation, the hydrogen gas on the cathode side will permeate to the anode side, when the hydrogen content in the oxygen gas of the anode exceeds 4 % will reach the explosion limit of hydrogen, posing a threat to the safe operation of the electrolyzer, so reducing the hydrogen content in the anode oxygen is an important guarantee to improve the safe operation of the electrolyzer.

The document (CN201711372053.6) introduced that by designing an air purification structure with a three-dimensional electrode structure, the pollutants in the air are purified by applying potential oxidation, which solves the problems of easy deactivation of catalysts and SO ₂ purification in the existing purification methods. However, the technical route of purifying the impurity gas by the potential oxidation method needs to consume extra electric energy, put forward additional requirements on the battery structure and materials, and has restrictions on the type of impurity gas, which is not used in the purification of the anode gas of the electrolytic cell. applicability. The literature (Journal of The Electrochemical Society, 2021168114513) reports that carbon and nitrogen compounds are used as cathode catalysts, which can meet the requirements of hydrogen evolution and oxygen reduction activity at the same time, and have obvious effects in reducing the oxygen content in cathode hydrogen. Although nitrogen compounds can achieve a good gas purification effect at the cathode, the anode is mainly faced with a strong oxidizing environment, and carbonitride materials are easily corroded. Therefore, the material selection of the gas purification layer on the anode side faces greater challenges. The precious metal material used in the present invention has quantitative chemical stability, and can maintain a stable structure in the strong oxidizing environment of the anode of the electrolytic cell.

SUMMARY OF THE INVENTION

Based on the above-mentioned background technology, the purpose of the present invention is to solve the problem of improving the safety and Faradaic efficiency of the anode of the existing solid electrolyte water electrolyzer. The method can remove hydrogen from oxygen to achieve the effect of reducing the hydrogen content. The addition of the optimized layer can avoid adding additional oxygen-in-hydrogen separation devices, achieve the purification effect of oxygen, improve the Faradaic efficiency of gas production, and prevent the hydrogen concentration from reaching the explosion limit, which is important for high-pressure operation or safety improvement of thin-film electrodes significance.

In order to achieve the above objects, the present invention provides a membrane electrode for improving the operational safety and efficiency of a solid electrolyte electrolytic cell, the membrane electrode includes an optimized layer, and the optimized layer is located between the anode catalytic layer and the proton exchange membrane, or the optimized The layer is located outside the anode catalytic layer, or the optimized layer is located on any one or both of the anode catalytic layers; the active component of the optimized layer is a hydrogen quencher with hydrogen adsorption or hydrogen oxidation activity.

Based on the above technical solutions, preferably, the specific types of the active components include noble metal catalysts such as Pt, Pd, and PtPd alloys.

Based on the above technical solutions, the preferred optimized layer can be prepared by spraying, screen printing, blade coating and other processes.

Based on the above technical solutions, preferably, the above-mentioned optimized layer is prepared by slurry, the composition of the optimized layer slurry includes active components, solvents and binders, and the types of solvents include volatile organic solvents such as ethanol and isopropanol ; The binder is a polymer resin with proton conductivity, such as perfluorosulfonic acid resin. When the optimized layer is located between the anode catalytic layer and the proton exchange membrane, the mass ratio of the binder to the active component is in the range of 0.45 to 2:1, preferably 0.5 to 1:1, and the solvent to the active component The mass ratio of the binder is 20-100:1, preferably 60-80:1; when the optimized layer is located outside the anode catalyst layer or is doped into the anode catalyst, the mass ratio of the binder to the active component ranges It is 0.1-0.4:1, preferably 0.2-0.4:1, and the mass ratio of solvent to active component is 20-100:1, preferably 60-80:1.

The optimized layer assembly position of the present invention is located between the anode catalytic layer and the proton exchange membrane, or located outside the anode catalytic layer, or mixed in any one or both of the anode catalytic layers. The position of the optimized layer is achieved by different preparation sequences of the slurry. When the optimized layer is located between the anode catalytic layer and the proton exchange membrane, the optimized layer is prepared before the anode catalytic layer is assembled; when the optimized layer is located outside the anode catalytic layer, the optimized layer is prepared before the assembly of the anode catalytic layer. The slurry is performed after the anode catalyst layer is assembled; when the optimization layer is doped into the anode catalyst, the anode slurry and the optimization layer slurry are simultaneously prepared on the membrane surface.

Based on the above technical solutions, preferably, in the membrane electrode optimization layer, the mass ratio of the active components in the optimization layer to the catalyst in the anode catalytic layer is 0.05-10:1, preferably 0.05-2:1, more preferably 0.1 to 2:1.

According to the position and slurry of the above-mentioned optimized layer, the preparation process and steps are as follows:

1. Preparation of the optimized layer slurry: Weigh a quantitative amount of active components according to the electrode area and the optimized layer loading, take a quantitative amount of solvent and mix with the active components and then ultrasonicate for 10-15 minutes, until the active components are uniformly dispersed in the slurry Then, a certain amount of the catalyst mass of the binder was added, and the ultrasonic wave was continued for 30 minutes to complete the preparation process of the slurry.

2. Preparation of the optimized layer: The preparation of the optimized layer is carried out by spraying, screen printing, blade coating and other processes. The electrolyte membrane used for electrode loading is placed on the surface of the negative pressure hot table, and the temperature of the hot table is controlled at 30-120 °C. The cathode catalytic layer, anode catalytic layer and optimized layer were prepared on the surface of the electrolyte membrane according to the order of assembly required for the position of the optimized layer. After the end, the electrode was vacuum-dried at 60-80 °C to completely remove the residual solvent in the electrode, and the residual solvent in the electrode was completely removed. Fabrication of membrane electrodes with optimized layers.

beneficial effect

1. The preparation operation of the membrane electrode with the optimized layer provided by this application is simple and easy to operate, and only needs to add a step of preparation of the optimized layer to the traditional membrane electrode preparation process, and the preparation cost is low; the addition of the optimized layer can avoid the electrolytic cell. The addition of an additional gas purification device saves system cost and space and simplifies system operation.

2. When the optimized layer is located in the anode catalytic layer, the addition of the optimized layer can realize the dispersion effect on the anode catalytic layer, improve the dispersion and quality activity of the catalyst, reduce the loading of the anode catalyst, and ensure the polarization of the membrane electrode. Purification of the anode side gas is achieved without compromising performance.

3. When the optimized layer is located between the anode catalytic layer and the proton exchange membrane, the optimized layer has a higher content of binder, which can enhance the binding force between the anode catalytic layer and the proton exchange membrane, promote proton transport, optimize The layer serves both binding and purification functions. On the one hand, the detachment of the anode catalytic layer during long-term operation is avoided, and the influence of the addition of the optimized layer on the proton transport capacity is alleviated; Effect;

4. When the optimized layer is located outside the catalytic layer, it is helpful to realize the purification of the gas on the anode side without affecting the polarization performance of the membrane electrode. At the same time, it can also purify the anode deionized water. Before the deionized water reaches the anode catalytic layer, the filter and adsorption of the optimized layer are used to remove insoluble impurities and metal ions in the circulating water, which helps to improve the membrane electrode. In addition, the outer optimized layer can also act as a protective layer for the anode catalytic layer to avoid the loss of the catalyst in the catalytic layer and the damage by mechanical external force.

5. Through the optimization of the membrane electrode by the optimization layer, the gas purity and hydrogen concentration on the anode side of the electrolytic cell can be realized beyond the explosion limit without significantly increasing the system cost and auxiliary equipment, so as to achieve the effect of improving efficiency and safe operation.

Description of drawings

Fig. 1 The cross-sectional topography and element distribution of the membrane electrode with the optimized layer prepared in Example 1.

Fig. 2 The concentration of anode hydrogen in the electrolytic cell with optimized layer membrane electrode (N115) prepared in Example 1.

Figure 3 The concentration of anode hydrogen in the electrolytic cell with optimized layer membrane electrode (N1135) prepared in Example 2.

Fig. 4 Anode hydrogen concentration of the membrane electrode (N212) electrolytic cell with optimized layer prepared in Example 3.

Figure 5 Anode hydrogen concentration of the electrolytic cell with optimized layer membrane electrode (N1135) prepared in Example 4.

Figure 6 compares the anode hydrogen concentration of the membrane electrode (N115) electrolytic cell prepared in Example 1 without an optimized layer.

Detailed ways

The following non-limiting examples may enable those of ordinary skill in the art to more fully understand the present invention, but do not limit the present invention in any way.

Example 1

1. Preparation of optimized layer slurry: Weigh 25.6 mg of platinum black catalyst, take 1.54 g of isopropanol and mix with the catalyst and then ultrasonicate for 10 min. After the catalyst is uniformly dispersed in the slurry, add 256 mg of Nafion solution (concentration is 5wt%) ), continue to sonicate for 30 min to complete the preparation of the slurry.

2. Preparation of cathode catalytic layer slurry: Weigh 57.14 mg of platinum-carbon catalyst (platinum loading is 70 wt%), add 4.5 g of isopropanol, ultrasonicate for 10 min, and add 381 mg of Nafion solution ( Concentration is 5wt%), continue to sonicate for 30min to complete the preparation of the slurry.

3. Preparation of anode catalyst layer slurry: Weigh 100mg of iridium black catalyst, add 6g of isopropanol, ultrasonicate for 10min, add 667mg Nafion solution (concentration is 5wt%) after the catalyst is evenly dispersed in the slurry, continue to ultrasonicate for 30min, The preparation of the slurry is completed.

4. Preparation of membrane electrode with optimized layer: use spraying method, take an appropriate size of Nafion115 film and place it on the surface of negative pressure hot stage, the temperature of the hot stage is controlled at 80 ℃, according to the order of spraying required for the position of the optimized layer, in turn The cathode catalyst layer slurry was sprayed on one side of the membrane, and then the optimization layer slurry and the anode catalyst layer slurry were sprayed on the other side of the membrane in turn to complete the preparation of membrane electrodes with an effective area of 50 cm ² . After spraying, the electrode was vacuum-dried at 80°C to completely remove the residual solvent in the electrode, and the preparation of the membrane electrode with the optimized layer was completed.

This example is a membrane electrode with an optimized layer prepared by using a 115 membrane (125 μm) as the electrolyte membrane, and the optimized layer is located between the anode catalyst and the Nafion115 membrane. The optimized layer location is as expected, between the anode catalytic layer and the Nafion115 membrane. The electrolytic cell performance test was carried out on the membrane electrode. The hydrogen concentration in the anode oxygen was 0.017%. Compared with the electrode without the optimized layer in the comparative example, the hydrogen concentration in the oxygen was significantly reduced.

Example 2

1. Preparation of optimized layer slurry: Weigh 50 mg of platinum-palladium catalyst (with a Pt loading of 60 wt%), take 3 g of isopropanol and mix with the catalyst and then ultrasonicate for 10 min. After the catalyst is uniformly dispersed in the slurry, add the catalyst mass 333 mg of Nafion solution (concentration of 5 wt %) was continued to be sonicated for 30 min to complete the preparation of the slurry.

2. Preparation of cathode catalytic layer slurry: Weigh 57.14 mg of platinum-carbon catalyst (platinum loading is 70 wt%), add 4.5 g of isopropanol, ultrasonicate for 10 min, and add 381 mg of Nafion solution ( Concentration is 5wt%), continue to sonicate for 30min to complete the preparation of the slurry.

3. Preparation of anode catalyst layer slurry: Weigh 100mg of iridium black catalyst, add 6g of isopropanol, ultrasonicate for 10min, add 667mg Nafion solution (concentration is 5wt%) after the catalyst is evenly dispersed in the slurry, continue to ultrasonicate for 30min, The preparation of the slurry is completed.

4. Preparation of membrane electrode with optimized layer: The preparation of the optimized layer is carried out by spraying method. A certain size of Nafion1135 film is placed on the surface of the negative pressure hot stage. In order, the cathode catalyst layer slurry was sprayed on one side of the membrane in turn, and then the anode catalyst layer slurry and the optimization layer slurry were sprayed on the other side of the membrane in turn to complete the preparation of membrane electrodes with an effective area of 50 cm ² . After spraying, the electrode was vacuum-dried at 80°C to completely remove the residual solvent in the electrode, and the preparation of the membrane electrode with the optimized layer located outside the anode catalytic layer was completed.

This example is a membrane electrode with an optimized layer prepared by using N1135 membrane (75 μm) as the electrolyte membrane. The optimized layer is located outside the anode catalyst. The electrolytic cell performance test of the membrane electrode is carried out. The hydrogen concentration in the anode oxygen is 0.022%. For the N115 membrane electrode with a higher thickness without adding the optimized layer in the comparative example, the hydrogen concentration is still significantly reduced.

Example 3

1. Preparation of slurry for optimization layer and anode catalytic layer: Weigh 10 mg of platinum-palladium catalyst (with a Pt loading of 60 wt%) and 100 mg of iridium black catalyst in the same sample bottle, take 6.6 g of isopropanol and mixed catalyst in ultrasonic For 10 min, after the catalyst was uniformly dispersed in the slurry, a catalyst mass of 733 mg Nafion solution (concentration of 5 wt %) was added, and the sonication was continued for 30 min to complete the preparation of the slurry.

2. Preparation of cathode catalytic layer slurry: Weigh 57.14 mg of platinum-carbon catalyst (platinum loading is 70 wt%), add 4.5 g of isopropanol, ultrasonicate for 10 min, and add 667 mg of Nafion solution ( Concentration is 5wt%), continue to ultrasonic for 30min to complete the preparation of cathode slurry.

3. Preparation of membrane electrode with optimized layer: using the blade coating method, take a certain size of Nafion212 membrane and place it on the surface of the negative pressure hot stage, the temperature of the hot stage is controlled at 80 ℃, and the cathode catalytic layer is sequentially scraped on one side of the membrane , and then scrape the mixed slurry of the optimized layer and the anode catalytic layer on the other side of the membrane to complete the preparation of the membrane electrode with an effective area of 50 cm ² . After the blade coating, the electrode was vacuum-dried at 80°C to completely remove the residual solvent in the electrode, and the preparation of the membrane electrode with the optimized layer located outside the anode catalytic layer was completed.

This example is a membrane electrode with an optimized layer prepared by using a 212 membrane (50 μm) as the electrolyte membrane. The optimized layer is dispersed in the anode catalytic layer. The electrolytic cell performance test is carried out on the membrane electrode. The hydrogen concentration in the anode oxygen is 0.044%, and the Compared with the N115 membrane electrode with a higher thickness without adding the optimized layer in the comparative example, the hydrogen concentration is still significantly reduced.

Example 4

1. Preparation of optimized layer slurry: Weigh 50 mg of platinum-palladium catalyst (with a Pt loading of 60 wt%), take 3 g of isopropanol and mix with the catalyst and then ultrasonicate for 10 min. After the catalyst is uniformly dispersed in the slurry, add the catalyst mass 500 mg of Nafion solution (concentration of 5 wt %) was continued to be sonicated for 30 min to complete the preparation of the optimized layer slurry.

2. Preparation of cathode catalytic layer slurry: Weigh 57.14 mg of platinum-carbon catalyst (platinum loading is 70 wt%), add 4.5 g of isopropanol, ultrasonicate for 10 min, and add 381 mg of Nafion solution ( Concentration is 5wt%), continue to sonicate for 30min to complete the preparation of the slurry.

3. Preparation of anode catalyst layer slurry: Weigh 100mg of iridium black catalyst, add 6g of isopropanol, ultrasonicate for 10min, add 667mg Nafion solution (concentration is 5wt%) after the catalyst is evenly dispersed in the slurry, continue to ultrasonicate for 30min, The preparation of the slurry is completed.

4. Preparation of membrane electrode with optimized layer: The preparation of the optimized layer is carried out by spraying method. A certain size of Nafion1135 film is placed on the surface of the negative pressure hot stage. In order, the cathode catalyst layer slurry was sprayed on one side of the membrane in turn, and then the anode catalyst layer slurry and the optimization layer slurry were sprayed on the other side of the membrane in turn to complete the preparation of membrane electrodes with an effective area of 50 cm ² . After spraying, the electrode was vacuum-dried at 80°C to completely remove the residual solvent in the electrode, and the preparation of the membrane electrode with the optimized layer located outside the anode catalytic layer was completed.

This example is a membrane electrode with an optimized layer prepared by using N1135 membrane (75 μm) as the electrolyte membrane, wherein the optimized layer is located outside the anode catalyst, and the mass ratio of the binder to the active component is 0.5:1. Electrolysis of the membrane electrode is carried out. In the cell performance test, the hydrogen concentration in the anodic oxygen was 0.109%. Compared with Example 2, the hydrogen content increased significantly. Compared with the N115 membrane electrode with a higher thickness and no optimized layer added in the comparative example, the hydrogen concentration was still significantly reduced. , indicating that the role of the optimization layer still exists.

Comparative Example 1

1. Preparation of cathode catalytic layer slurry: Weigh 57.14 mg of platinum-carbon catalyst (platinum loading is 70 wt%), add 4.5 g of isopropanol, ultrasonicate for 10 min, and add 381 mg of Nafion solution ( Concentration is 5wt%), continue to sonicate for 30min to complete the preparation of the slurry.

2. Preparation of anode catalyst layer slurry: Weigh 100mg of iridium black catalyst, add 6g of isopropanol, ultrasonicate for 10min, add 667mg of Nafion solution (concentration of 5wt%) after the catalyst is evenly dispersed in the slurry, continue to ultrasonicate for 30min, The preparation of the slurry is completed.

3. Preparation of membrane electrodes without an optimized layer: use the spraying method, take a certain size of Nafion115 membrane and place it on the surface of a negative pressure hot stage, the temperature of the hot stage is controlled at 80 ℃, and then spray the cathode catalytic layer on both sides of the membrane, The anode catalyst layer slurry was used to complete the preparation of membrane electrodes with an effective area of 50 cm ² . After spraying, the electrode was vacuum-dried at 80° C. to completely remove the residual solvent in the electrode, and the preparation of the membrane electrode was completed.

Comparative Example 1 is a membrane electrode without an optimized layer prepared with a 115 membrane as the electrolyte membrane. The electrolytic cell performance test of the membrane electrode shows that the hydrogen concentration in oxygen is 0.209%, which is significantly higher than that of the membrane electrode with the optimized layer in the present application.

Claims (7)

1. a membrane electrode for a solid electrolyte electrolyzer, characterized in that the membrane electrode comprises an optimized layer; the optimized layer is located between the anode catalytic layer and the proton exchange membrane, or the optimized layer is located outside the anode catalytic layer, Or the optimized layer is located in one or both of the anode catalytic layers; the active component of the optimized layer is a catalyst with hydrogen adsorption or hydrogen oxidation function. 2 . The membrane electrode according to claim 1 , wherein the active component is at least one of Pt, Pd, and PtPd alloys. 3 . 3. The membrane electrode according to any one of claims 1-2, wherein the optimized layer can prepare the active component on the membrane electrode by spraying, screen printing or blade coating process. 4 . The membrane electrode according to claim 3 , wherein the optimized layer is prepared into the membrane electrode in the form of a slurry, and the slurry comprises active components, a binder, and a solvent; the bonding The solvent is a polymer resin with proton conduction function; the solvent is a volatile organic solvent. 5 . The membrane electrode according to claim 4 , wherein the binder is perfluorosulfonic acid resin; and the solvent is ethanol or isopropanol. 6 . 6. membrane electrode according to claim 3 is characterized in that, the assembling sequence of optimization layer on membrane electrode is carried out according to position structure; When optimization layer is located between anode catalytic layer and proton exchange membrane, optimization layer is in anode catalytic layer. It is prepared on the surface of the proton exchange membrane before layer assembly, and in the slurry of the optimized layer, the mass ratio of the binder to the active component is 0.45-2:1, and the mass ratio of the solvent to the active component is 20-100:1 ; When the optimized layer is located outside the anode catalytic layer, the optimized layer is prepared after the anode catalytic layer is assembled; when the optimized layer is doped into the anode catalyst, the anode catalytic layer slurry and the optimized layer slurry are simultaneously dispersed on the surface of the proton exchange membrane; In the slurry of the optimized layer, the mass ratio of the binder to the active component is 0.1-0.4:1, and the mass ratio of the solvent to the active component is 20-100:1. 7 . The membrane electrode according to claim 1 , wherein the mass ratio of the active components in the optimized layer to the catalyst in the anode catalytic layer is 0.05-10:1. 8 .

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