CN108598494B - A fuel cell anode and fuel cell using the same - Google Patents

Abstract

The invention relates to a fuel cell anode and a fuel cell using the anode, comprising a lead wire, a foamed nickel electrode plate and a catalyst layer, the catalyst layer is coated on one side of the foamed nickel electrode plate, the lead wire is connected with the foamed nickel electrode plate, and the catalyst layer The structure of the catalyst used is a honeycomb structure. The invention solves the technical problems of high cost and low catalytic performance of the existing electrodes for fuel cells. The catalyst structure used in the electrode of the present invention is a three-dimensional sheet honeycomb structure and a graphene-like structure. Compared with the spherical, core-shell structure or hollow structure reported in the literature, this structure can provide a larger contact area for the reactants and promote the reactants. The diffusion of the catalyst increases the mass transfer rate and improves the catalytic performance of the catalyst.

Description

A fuel cell anode and fuel cell using the same

technical field

The invention belongs to the technical field of fuel cells, and in particular relates to a fuel cell anode and a fuel cell using the anode.

Background technique

In recent years, fuel cells have become a high-tech project developed by countries all over the world. It is an efficient and clean electrochemical power generation device that directly converts the chemical energy of reactants into electrical energy. The fuel can use hydrogen, alcohol, hydrocarbon, borohydride, etc., and the oxidant generally uses oxygen or air. On the road to commercialization of low temperature fuel cells such as proton exchange membrane fuel cells (PEMFC), methanol fuel cells (DMFC), and borohydride fuel cells (DBFC), the durability and cost of fuel cells are two major challenges, among which Reducing the noble metal content in the electrode assembly can directly improve the cost-effectiveness of the battery, but it also affects the performance and long-term stability of the battery. At present, reducing the cost of electrode assemblies is mainly achieved by reducing the cost of electrode catalysts. The main way to reduce the cost of electrode catalysts is There are the following types: (1) platinum alloy is prepared to reduce platinum content. Chinese patent CN 102820475 A introduces a platinum alloy catalyst PtXNb, wherein X is nickel, cobalt, chromium, copper, titanium or manganese, and is characterized in that platinum The atomic percentage of the catalyst is 46-75at%, and the catalyst is used as a fuel cell, especially a phosphoric acid fuel cell cathode with good oxygen reduction catalytic activity. However, the preparation route of this method is complicated and the process is relatively harsh, such as: it needs to be at a high temperature of 1000-1200 ℃ and annealing treatment in an inert atmosphere. CN101083325 A introduces a preparation method of a palladium-platinum alloy electrocatalyst, the method prepares nano-palladium or palladium-platinum catalyst by water phase fusion reduction and heat treatment method, the preparation method is simple, but synthetic The active component of the catalyst is still the precious metal platinum or palladium, which does not fundamentally solve the cost problem. Chinese patent CN101667644 A introduces a high-performance low-platinum catalyst preparation method, which, through a simple replacement reaction, converts a small amount of Pt or Pt, Ru is covered on the surface of the Pd alloy, and then jointly supported on the carbon powder, which greatly reduces the amount of precious metal Pt, and can be used in the cathode and anode of methanol fuel cells. Solve the cost problem. (2) Prepare a core-shell structure platinum catalyst to reduce the content of platinum and increase the utilization rate and dispersibility of platinum. For example: Chinese patent CN 10526853 A introduces a core-shell structure platinum catalyst, the advantage of which is that The preparation efficiency of the core-shell structure is improved, but the defect is that the preparation method is relatively complicated, and requires hydrazine hydrate reduction and high-temperature treatment. Chinese patent CN105702971B discloses a core-shell type gold@cobalt-boron catalyst for fuel cells. A gold-cobalt-boron alloy with a shell structure, wherein amorphous cobalt-boron is the shell and crystalline gold is the core. The structure has the common characteristics of both amorphous and crystalline materials, and has excellent catalytic performance, which can effectively improve the efficiency of fuel cells. The discharge performance greatly reduces the amount of precious metals, which significantly reduces the cost of fuel cells, which will help promote the development of fuel cells. Although the catalyst prepared by Chinese patent CN105702971B greatly reduces the amount of precious metals, the cost of fuel cells is significantly reduced. However, due to the core-shell structure, the contact area of the reactants is small, resulting in low catalytic performance of the electrode.

SUMMARY OF THE INVENTION

In order to solve the technical problems of high cost and low catalytic performance of the existing electrodes for fuel cells, the present invention provides a fuel cell and an electrode for fuel cells.

The technical scheme adopted in the present invention is:

A fuel cell anode, comprising a wire, a foamed nickel plate and a catalyst layer, the catalyst layer is coated on one side of the foamed nickel plate, the wire is connected to the foamed nickel plate, and is characterized in that: the catalyst layer The structure of the catalyst used is a honeycomb structure.

Further, the catalyst includes metal Ni element, Co element and B element, the molar ratio of Ni to Co is (0.01-1): 1, the molar ratio of Ni to B is 1: (2-5), and the molar ratio of Co to B is 1: (2-5). The ratio is 1:(2-5).

Further, the catalyst includes metal Ni, Co and B, the molar ratio of Ni to Co is 0.01:1, the molar ratio of Ni to B is 1:3, and the molar ratio of Co to B is 1:3.

Further, the catalyst is prepared by the following method:

Step 1. Configure borohydride-hydroxide mixed solution:

After weighing the borohydride, dissolve the borohydride in deionized water to prepare a borohydride solution, then add hydroxide to the borohydride solution until the pH of the solution is 12-13 to obtain a borohydride- Hydroxide mixed solution;

The borohydride is potassium borohydride, and the hydroxide is potassium hydroxide;

Step 2, configure the cobalt salt solution: take by weighing the cobalt salt according to the standard that the molar ratio of cobalt element and boron element is 1: (2-5), and dissolve the cobalt salt in deionized water to configure the cobalt salt solution;

Step 3. Prepare Co-B solution:

Under stirring conditions at a temperature of 0 °C, the borohydride-hydroxide mixed solution described in step 1 is added to the metal cobalt salt solution described in step 2 at a slow speed, and the reaction is continued after no gas is generated. Stir until the reaction is complete to obtain Co-B solution;

Step 4. Configure nickel salt solution:

Weigh the nickel salt, and dissolve the nickel salt in deionized water to prepare a nickel salt solution;

Step 5. Configure borohydride-hydroxide again:

Weigh the borohydride according to the standard that the molar ratio of nickel and boron is 1:(2-5), dissolve the borohydride in deionized water to prepare a borohydride solution, and then add hydroxide to the borohydride solution The pH value of the solution is 12-13 to obtain a borohydride-hydroxide mixed solution;

Step 6. Prepare mixed solution:

To the Co-B solution prepared in step 3, dropwise add the nickel salt solution prepared in step 4 and the borohydride-hydroxide solution prepared in step 5 at the same time, keep the reaction temperature at 0°C, and continue to stir after no gas is generated, until The reaction is complete to obtain a Ni-Co-B mixed solution;

Step 7. Preparation of Ni-Co-B catalyst:

The mixed solution prepared in step 6 is subjected to suction filtration, and then washed to neutrality, and the obtained product is dried in a vacuum drying oven at 60° C.-120° C. to obtain a honeycomb Ni-Co-B catalyst.

Further, the borohydride described in step 1 is potassium borohydride, and the concentration of the potassium borohydride solution configured is 0.2 mol/L; step 3: the borohydride-hydroxide mixed solution described in step 1 is The speed of 1mL/min～2mL/min is added to the metal cobalt salt solution described in step 2.

Further, the cobalt salt described in step 2 is cobalt chloride, and the molar ratio of cobalt element to potassium borohydride is 1:3; the cobalt salt solution is 0.1 mol/L.

Further, the nickel salt described in step 4 is nickel chloride; the concentration of the configured nickel salt solution is 0.01mol/L-0.1mol/L.

Further, in the step 5, the borohydride is potassium borohydride, and in the step 4, the mol ratio of the nickel element to the boron element in the step 5 is 1:3; the mol ratio of the metal Ni and Co described in the step 6 is (0.01-1 ):1.

Further, the vacuum degree of the vacuum drying in the seventh step is 80Pa～100Pa, the temperature is 60℃～120℃, and the drying time is 1h～8h.

A fuel cell using the above anode.

Compared with the prior art, the present invention has the following effects:

1. The catalyst structure used in the electrode of the present invention is a three-dimensional flake honeycomb structure and a graphene-like structure. Compared with the spherical, core-shell structure or hollow structure reported in the literature, this structure can provide a larger contact area for reactants and promote The diffusion of reactants increases the mass transfer rate and improves the catalytic performance of the catalyst. Ni-Co-B is the anode catalyst of direct borohydride fuel cell DBFC, and LaNi _0.9 Ru _0.1 O ₃ is the cathode catalyst. The maximum power density of the fuel cell is 90.58mW·cm ^-2 .

2. The catalyst constituent elements used in the electrode of the present invention are all non-precious metals, and the use of precious metals such as platinum is avoided, so that the cost of the fuel cell is greatly reduced.

3. The preparation method of the catalyst used in the electrode of the present invention is simple and easy to operate. It is prepared by a step-by-step reduction method, and the prepared catalyst has a uniform morphology.

Description of drawings

FIG. 1 is a schematic diagram of the anode structure of the fuel cell of the present invention;

Fig. 2 is the scanning electron microscope picture when the Ni-Co-B catalyst prepared in Example 2 of the present invention is magnified 25000 times;

Fig. 3 is the scanning electron microscope image when the Ni-Co-B catalyst prepared in Example 2 of the present invention is magnified 240,000 times;

4 is a comparison diagram of the cell performance of Ni-Co-B prepared in Example 2 of the present invention and Au@Co-B prepared by Chinese patent CN105702971B as anodes of direct borohydride fuel cells, respectively.

Detailed ways

The technical solutions of the present invention will be described in further detail below through examples.

Example 1

As shown in Figure 1, an electrode for a fuel cell includes a wire 1, a foamed nickel electrode plate 1 and a catalyst layer 3, the catalyst layer is coated on one side of the foamed nickel electrode plate, and the wire is located on the other side of the foamed nickel electrode plate , the structure of the catalyst used in the catalyst layer is a honeycomb structure. The catalyst includes metal Ni element, Co element and B element, the molar ratio of Ni to Co is 0.01:1, the molar ratio of Ni to B is 1:3, and the molar ratio of Co to B is 1:3.

A fuel cell includes a cathode, a fiber membrane and the anode electrode of Example 1, the cathode includes a cathode lead, a cathode plate and a cathode catalyst LaNi _0.9 Ru _0.1 O ₃ coated on the cathode plate. The anode electrode includes an anode wire, a foamed nickel electrode plate and a catalyst layer, the catalyst layer is coated on one side of the foamed nickel electrode plate, the wire is located on the other side of the foamed nickel electrode plate, and the catalyst used in the catalyst layer has a honeycomb structure. like structure.

The following lists several preparation examples of the catalyst of the present invention, and the performance of the fuel cell after using the catalyst.

Example 2

The catalyst of this embodiment is a nickel-cobalt-boron alloy with a honeycomb structure, and its preparation method adopts a step-by-step reduction method:

Step 1. Dissolve 1.19g of cobalt chloride hexahydrate in 50ml of deionized water to prepare a 0.1mol/L cobalt salt solution;

Step 2, dissolve 0.81g potassium borohydride in deionized water to form a potassium borohydride solution with a concentration of 0.2mol/L, then add an appropriate amount of potassium hydroxide solution to the potassium borohydride solution to a pH of 12, Obtain potassium borohydride-potassium hydroxide mixed solution;

Step 3. Add 75 ml of 0.2 mol/L potassium borohydride-potassium hydroxide solution to the cobalt chloride solution of Step 1 at a speed of 1 mL/min under vigorous stirring at 0 ° C, and continue after the reaction has no gas generation. Stir for 1h until the reaction is complete;

Step 4: Dissolve 0.71g of nickel chloride hexahydrate in 150ml of deionized water to prepare a 0.02mol/L nickel salt solution;

Step 5. Dissolve 0.054g of potassium borohydride in deionized water, configure it into a 0.2mol/L potassium borohydride solution, add an appropriate amount of potassium hydroxide, and adjust the pH value to 12;

Step 6. Add the potassium borohydride-potassium hydroxide mixed solution prepared in step 5 and the nickel chloride solution prepared in step 4 dropwise to the precipitation solution that is completely reacted in step 3 under ice bath conditions, until no gas is produced. Continue to stir for 2h until the reaction is complete;

Step 7: Wash the precipitate obtained in step 6 with deionized water repeatedly, then with absolute ethanol for 2 to 3 times, and vacuum dry at 80° C. and 80 pa for 4 hours to obtain a honeycomb structure Ni-Co-B catalyst.

The product prepared in this example is physically characterized, and FIG. 2 is a SEM scanning image of Ni-Co-B at low magnification. FIG. 3 is a SEM scanning image of Ni-Co-B at high magnification. It can be seen from the figure that the Ni-Co-B synthesized according to Example 1 has a honeycomb three-dimensional lamellar structure. Figure 4 is a fuel cell assembled with Ni-Co-B prepared in this example as the anode catalyst of the direct borohydride fuel cell DBFC and LaNi _0.9 Ru _0.1 O ₃ as the cathode catalyst. The maximum power density of the fuel cell was measured to reach 90.58mW cm ^-2 ; under the same conditions, compared with the performance of the Chinese patent CN105702971B core-shell catalyst (Au@Co-B) as the DBFC anode of the direct borohydride fuel cell, the Ni-Co- B catalyst, the battery discharge performance is significantly improved.

Example 3

The catalyst of this embodiment is a honeycomb structure nickel-cobalt-boron alloy, and the preparation method adopts a step-by-step reduction method:

Step 1. Dissolve 2.38g of cobalt chloride hexahydrate in 50ml of deionized water to prepare a 0.2mol/L cobalt salt solution;

Step 2, dissolve 1.62g of potassium borohydride in deionized water to form a potassium borohydride solution with a concentration of 0.3mol/L, then add an appropriate amount of potassium hydroxide solution to the potassium borohydride solution to a pH of 13, Obtain potassium borohydride-potassium hydroxide mixed solution;

Step 3. Add 100ml of 0.3mol/L potassium borohydride-potassium hydroxide solution to the cobalt chloride solution of step 1 at a speed of 2mL/min under vigorous stirring at 0°C, and continue after the reaction has no gas generation. Stir for 1h until the reaction is complete;

Step 4. Dissolve 0.36g of nickel chloride hexahydrate in 150ml of deionized water to prepare a 0.01mol/L nickel salt solution;

Step 5. Dissolve 0.243 g of potassium borohydride in deionized water, configure it into a 0.3 mol/L potassium borohydride solution, add an appropriate amount of potassium hydroxide, and adjust the pH value to 13;

Step 6. Add the potassium borohydride-potassium hydroxide mixed solution prepared in step 5 and the nickel chloride solution prepared in step 4 dropwise to the precipitation solution that is completely reacted in step 3 under ice bath conditions, until no gas is produced. Continue to stir for 2h until the reaction is complete;

Step 7: Wash the precipitate obtained in step 6 repeatedly with deionized water, then with absolute ethanol for 2 to 3 times, and vacuum dry at 80° C. and 80 pa for 4 hours to obtain a honeycomb structure Ni-Co-B catalyst.

The product prepared in this example was physically characterized, and the result was the same as Example 1, and it was a honeycomb three-dimensional sheet structure. The Ni-Co-B prepared in this example was used as the anode catalyst of the direct borohydride fuel cell DBFC, and LaNi _0.9 Ru _0.1 O ₃ was used as the cathode catalyst to assemble the fuel cell. The maximum power density of the fuel cell was 88.45 mW·cm ^-2 .

Example 4

The catalyst of this embodiment is a honeycomb structure nickel-cobalt-boron alloy, and the preparation method adopts a step-by-step reduction method:

Step 1. Dissolve 3.81g of cobalt chloride hexahydrate in 100ml of deionized water to prepare a 0.16mol/L cobalt salt solution;

Step 2, dissolve 1.29g of potassium borohydride in deionized water to form a potassium borohydride solution with a concentration of 0.4mol/L, then add an appropriate amount of potassium hydroxide solution to the potassium borohydride solution to a pH of 12, Obtain potassium borohydride-potassium hydroxide mixed solution;

Step 3. Add 60 ml of 0.4 mol/L potassium borohydride-potassium hydroxide solution to the cobalt chloride solution of step 1 at a speed of 1 mL/min under vigorous stirring at 0 ° C, and continue after the reaction has no gas generation. Stir for 1h until the reaction is complete;

Step 4. Dissolve 1.19g of nickel chloride hexahydrate in 100ml of deionized water to prepare a 0.05mol/L nickel salt solution;

Step 5: Dissolve 0.81 g of potassium borohydride in deionized water, configure it into a 0.3 mol/L potassium borohydride solution, add an appropriate amount of potassium hydroxide, and adjust the pH value to 13;

Step 6. The potassium borohydride-potassium hydroxide mixed solution prepared in step 5 and the nickel chloride solution prepared in step 4 are added dropwise to the precipitation solution that is completely reacted in step 3 under ice bath conditions, and accompanied by vigorous stirring , and continue stirring for 2h until no gas is produced until the reaction is complete;

Step 7. The precipitate obtained in step 6 is repeatedly washed with deionized water, then washed with absolute ethanol for 2-3 times, and vacuum dried at 80° C. and 80pa for 5h to obtain a honeycomb structure Ni-Co-B catalyst.

The product prepared in this example was physically characterized, and the result was the same as Example 1, and it was a honeycomb three-dimensional sheet structure. The Ni-Co-B prepared in this example was used as the anode catalyst of the direct borohydride fuel cell DBFC, and LaNi _0.9 Ru _0.1 O ₃ was used as the cathode catalyst to assemble the fuel cell. The maximum power density of the fuel cell was 91.08 mW·cm ^-2 .

Example 5

The catalyst of this embodiment is a honeycomb structure nickel-cobalt-boron alloy, and the preparation method adopts a step-by-step reduction method:

Step 1. Dissolve 23.793g of cobalt chloride hexahydrate in 100ml of deionized water to prepare a 1mol/L cobalt salt solution;

Step 2, dissolve 10.788g of potassium borohydride in deionized water to form a potassium borohydride solution with a concentration of 1 mol/L, then add an appropriate amount of potassium hydroxide solution to the potassium borohydride solution to a pH of 13 to obtain Potassium borohydride-potassium hydroxide mixed solution;

Step 3. Add 200 ml of 1 mol/L potassium borohydride-potassium hydroxide solution to the cobalt chloride solution in step 1 at a speed of 2 mL/min under vigorous stirring at 0 °C, and continue to stir after no gas is generated in the reaction. 1h, until the reaction is complete;

Step 4. Dissolve 23.769g of nickel chloride hexahydrate in 100ml of deionized water to prepare a 1mol/L nickel salt solution;

Step 5. Dissolve 5.394g potassium borohydride in deionized water, configure it into a 1mol/L potassium borohydride solution, add an appropriate amount of potassium hydroxide, and adjust the pH to 13;

Step 6. The potassium borohydride-potassium hydroxide mixed solution prepared in step 5 and the nickel chloride solution prepared in step 4 are added dropwise to the precipitation solution that is completely reacted in step 3 under ice bath conditions, and accompanied by vigorous stirring , and continue stirring for 2h until no gas is produced until the reaction is complete;

Step 7: The precipitate obtained in step 6 is repeatedly washed with deionized water, then washed with absolute ethanol for 2 to 3 times, and vacuum dried at 60° C. and 80 pa for 6 hours to obtain a honeycomb structure Ni-Co-B catalyst.

The product prepared in this example was physically characterized, and the result was the same as Example 1, and it was a honeycomb three-dimensional sheet structure. The Ni-Co-B prepared in this example was used as the anode catalyst of the direct borohydride fuel cell DBFC, and LaNi _0.9 Ru _0.1 O ₃ was used as the cathode catalyst to assemble the fuel cell. The maximum power density of the fuel cell was 82.37 mW·cm ^-2 .

The above are only preferred embodiments of the present invention and do not limit the present invention. Any simple modifications, changes and equivalent changes made to the above embodiments according to the technical essence of the present invention still belong to the technical solutions of the present invention. within the scope of protection.

Claims (6)

1. A fuel cell anode, comprising a wire, a nickel foam electrode plate and a catalyst layer, the catalyst layer is coated on one side of the nickel foam electrode plate, the wire is connected with the nickel foam electrode plate, and the catalyst layer uses The structure of the catalyst is a honeycomb structure; It is characterised in that the catalyst is prepared by the following method: Step 1. Configure borohydride-hydroxide mixed solution: After weighing the borohydride, dissolve the borohydride in deionized water to prepare a borohydride solution, then add hydroxide to the borohydride solution until the pH of the solution is 12-13 to obtain a borohydride- Hydroxide mixed solution; The borohydride is potassium borohydride, and the hydroxide is potassium hydroxide; Step 2, configure the cobalt salt solution: take by weighing the cobalt salt according to the standard that the molar ratio of cobalt element and boron element is 1: (2-5), and dissolve the cobalt salt in deionized water to configure the cobalt salt solution; Step 3. Prepare Co-B solution: Under stirring conditions at a temperature of 0 °C, the borohydride-hydroxide mixed solution described in step 1 was added to the cobalt salt solution described in step 2 at a rate of 1 mL/min to 2 mL/min, and the reaction was Continue to stir after no gas is generated until the reaction is complete to obtain a Co-B solution; Step 4. Configure nickel salt solution: Weigh the nickel salt, and dissolve the nickel salt in deionized water to prepare a nickel salt solution; Step 5. Configure borohydride-hydroxide again: Weigh the borohydride according to the standard that the molar ratio of nickel and boron is 1:(2-5), dissolve the borohydride in deionized water to prepare a borohydride solution, and then add hydroxide to the borohydride solution The pH value of the solution is 12-13 to obtain a borohydride-hydroxide mixed solution; Step 6. Prepare mixed solution: To the Co-B solution prepared in step 3, dropwise add the nickel salt solution prepared in step 4 and the borohydride-hydroxide solution prepared in step 5 at the same time, keep the reaction temperature at 0°C, and continue to stir after no gas is generated, until The reaction is complete to obtain a Ni-Co-B mixed solution; Step 7. Preparation of Ni-Co-B catalyst: The mixed solution prepared in step 6 is subjected to suction filtration, and then washed to neutrality, and the obtained product is dried in a vacuum drying oven at 60° C.-120° C. to obtain a honeycomb Ni-Co-B catalyst. 2 . The fuel cell anode according to claim 1 , wherein the borohydride described in step 1 is potassium borohydride, and the concentration of the prepared potassium borohydride solution is 0.2 mol/L. 3 . 3. The fuel cell anode according to claim 2, wherein the cobalt salt in step 2 is cobalt chloride, and the molar ratio of cobalt element to potassium borohydride is 1:3; the cobalt salt solution is 0.1 mol /L. 4. The fuel cell anode according to claim 1, 2 or 3, wherein the nickel salt in step 4 is nickel chloride; the concentration of the configured nickel salt solution is 0.01mol/L-0.1mol/L. 5. The anode for a fuel cell according to claim 4, wherein the borohydride in step 5 is potassium borohydride, the molar ratio of nickel element in step 4 to boron element in step 5 is 1:3; in step 6 The molar ratio of the metal Ni to Co is (0.01-1):1. 6 . The fuel cell anode according to claim 5 , wherein the vacuum degree of the vacuum drying in step 7 is 80Pa～100Pa, the temperature is 60℃～120℃, and the drying time is 1h～8h. 7 .

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