Synthesis method of nickel-based non-noble metal catalyst, hydrogen electrode and preparation method thereof, and nickel-hydrogen secondary battery

Abstract

The invention provides a synthesis method of a cheap nickel-based non-noble metal catalyst, a hydrogen electrode and a preparation method thereof, and a nickel-hydrogen secondary battery, and belongs to the technical field of chemical energy storage. The synthesis method of the nickel-based non-noble metal catalyst comprises the steps that a non-noble metal salt solution and a molybdate solution are mixed, an amorphous precursor is obtained after ultrasonic treatment, and the non-noble metal salt solution comprises a nickel salt solution; after annealing in air or inert atmosphere, converting the amorphous precursor into a crystalline intermediate; and reducing the crystalline intermediate in H2 / Ar mixed gas to obtain the nickel-based non-noble metal catalyst. The invention also provides a hydrogen electrode comprising the nickel-based non-noble metal catalyst, a preparation method of the hydrogen electrode, and a nickel-hydrogen secondary battery using the hydrogen electrode.

Description

Technical Field

[0001] At least one embodiment of the present invention relates to a nickel-hydrogen secondary battery, and more particularly to a method for synthesizing a nickel-based non-precious metal catalyst, a hydrogen electrode and a method for preparing the same, and a nickel-hydrogen secondary battery. Background Art

[0002] At present, the consumption of non-renewable resources such as coal, oil, and natural gas is increasing year by year. The sole use of non-renewable resources will cause energy shortages. In addition, the carbon dioxide produced during use will cause ozone layer damage and further damage the environment. Renewable energy such as wind and light are often intermittent due to geographical and climatic restrictions. Using grid-scale battery energy storage technology to store energy can smooth out the uncertainty caused by renewable energy caused by environmental intermittency.

[0003] Among the current grid-scale storage systems, electrochemical energy storage systems are currently the most popular due to their long cycle life and high energy density, and are considered to be the most promising energy storage technology. However, most battery technologies such as lithium-ion batteries, vanadium redox flow batteries, and lead-acid batteries cannot meet the requirements in terms of high safety, low cost, and long service life. In recent years, hydrogen batteries, especially nickel-hydrogen secondary batteries, have been proven to have ultra-long life and high safety, showing great potential in battery grid-scale energy storage. The biggest feature of hydrogen batteries is that the anode reaction is a bifunctional reversible catalytic reaction of hydrogen evolution reaction (HER) / hydrogen oxidation reaction (HOR), which exhibits ultra-stable durability under commercial platinum-based metal catalysts. However, the cost of platinum-based metal catalysts is relatively high, so it is very important to develop cheaper catalysts to replace traditional platinum-based metal catalysts. Summary of the invention

[0004] In view of this, in order to at least partially solve the above-mentioned technical problems, the present invention provides a method for synthesizing a nickel-based non-precious metal catalyst, a hydrogen electrode and a preparation method thereof, and a nickel-hydrogen secondary battery.

[0005] According to an embodiment of one aspect of the present invention, a method for synthesizing a nickel-based non-precious metal catalyst is provided, comprising: mixing a non-precious metal salt solution with a molybdate solution to obtain an amorphous precursor after ultrasound, wherein the non-precious metal salt solution includes a nickel salt solution; after annealing in air or an inert atmosphere, the amorphous precursor is converted into a crystalline intermediate; and in a H2 / Ar mixed gas, the crystalline intermediate is reduced to obtain a nickel-based non-precious metal catalyst.

[0006] According to an embodiment of one aspect of the present invention, the present invention provides a method for preparing a hydrogen electrode for a nickel-hydrogen secondary battery, comprising: preparing a nickel-based non-precious metal catalyst by the above-mentioned synthesis method; mixing the nickel-based non-precious metal catalyst, a binder and a solvent to form a slurry; and spraying the slurry on a gas diffusion electrode to obtain a hydrogen electrode after vacuum drying.

[0007] According to another embodiment of the present invention, the present invention provides a hydrogen electrode prepared by the above preparation method.

[0008] According to another embodiment of the present invention, the present invention provides a nickel-hydrogen secondary battery, comprising:

[0009] Electrolyte;

[0010] a positive electrode comprising nickel hydroxide adapted to undergo a redox reaction between the nickel hydroxide and the nickel oxyhydroxide at an interface between the positive electrode and an electrolyte; and

[0011] The negative electrode, including the above-mentioned hydrogen electrode, is suitable for performing a redox reaction between H2O and gaseous H2 at the interface between the negative electrode and the electrolyte.

[0012] According to the synthesis method of the nickel-based non-precious metal catalyst provided in the above embodiment of the present invention, cheap non-precious metal materials are used, and the catalyst precursor can be quickly and large-scale obtained by a rapid co-precipitation method, and then a material with HER / HOE catalytic activity can be obtained by heat treatment and reduction, thereby enabling low-cost preparation of a hydrogen electrode with good polarization performance, and the prepared hydrogen electrode is applied to a nickel-hydrogen secondary battery, which can achieve an energy density similar to or better than that of the nickel-hydrogen secondary battery in the related art. At the same time, since the preparation method of the nickel-based non-precious metal catalyst and the hydrogen electrode of the present invention is simple and the price of the raw materials used is low, the cost of preparing nickel-hydrogen secondary batteries can also be reduced, which is conducive to large-scale commercial preparation of hydrogen electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0014] Figure 1 A schematic diagram of a nickel-hydrogen secondary battery provided by an embodiment of the present invention;

[0015] Figure 2 XRD spectrum of the nickel-based non-precious metal catalyst Ni / MoO2 provided in Example 1 of the present invention;

[0016] Figure 3Polarization curve and stability test diagram of hydrogen redox reaction catalytic test of the hydrogen electrode provided in Example 1 of the present invention at 26%wt KOH vs. reversible hydrogen standard potential;

[0017] Figure 4 A charge and discharge curve diagram of a nickel-hydrogen secondary battery assembled with the hydrogen electrode provided in Example 2 of the present invention as the negative electrode at different current densities;

[0018] Figure 5 The nickel-hydrogen secondary battery assembled with the hydrogen electrode provided in Example 2 of the present invention as the negative electrode is 7.5 mA / cm 2 Cyclic performance test result diagram at current density of;

[0019] Figure 6 The nickel-hydrogen secondary battery (Ni-H2 (Pt / C@GDL) battery) assembled with the commercial catalytic electrode Pt / C@GDL as the negative electrode in Comparative Example 1 and the nickel-hydrogen secondary battery assembled with the hydrogen electrode provided in Example 2 of the present invention as the negative electrode were respectively -2 The charge and discharge curves at the current density of ;

[0020] Figure 7 A charge and discharge curve diagram of a nickel-hydrogen secondary battery assembled with the hydrogen electrode provided in Example 3 of the present invention as the negative electrode at different current densities;

[0021] Figure 8 A charge and discharge curve diagram of a nickel-hydrogen secondary battery assembled with the hydrogen electrode provided in Example 4 of the present invention as the negative electrode at different current densities;

[0022] Fig. 9 The charge and discharge curves of a nickel-hydrogen secondary battery assembled with the hydrogen electrode provided in Example 5 of the present invention as the negative electrode at different current densities.

[0023] Description of reference numerals:

[0024] 1- A diaphragm including an electrolyte;

[0025] 2- positive electrode;

[0026] 3- Negative electrode. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. However, the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the invention thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, for clarity, the sizes and relative sizes of layers and regions may be exaggerated, and the same reference numerals throughout represent the same elements.

[0028] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0029] Alkaline nickel-metal hydride batteries have attracted extensive attention from researchers due to their high reliability, excellent cycle stability and pollution-free properties. However, the large-scale promotion of alkaline nickel-metal hydride batteries is limited by the use of expensive precious metal platinum as a catalyst in the negative electrode. Therefore, it is very important to develop cheaper catalysts to replace traditional platinum-based metal catalysts.

[0030] Among the materials studied, nickel-based catalysts, as a non-precious metal catalyst, show good HER / HOR bifunctional catalytic activity. However, due to the unfavorable adsorption behavior of nickel on hydrogen, its activity is still much lower than that of Pt. In order to achieve catalytic activity comparable to that of platinum-based metal (PGM) catalysts, the mass loading of nickel-based catalysts often needs to be hundreds or even thousands of times that of PGM. Moreover, most of the nickel-based metal catalysts currently proposed are only in the laboratory stage, making it difficult to carry out large-scale commercial manufacturing, or the required large-scale commercial manufacturing costs are too high.

[0031] In view of this, the present invention designs a series of highly active, low-cost and scalable nickel-based catalysts as a bifunctional HER / HOR catalyst that can be used in secondary hydrogen batteries. The cost of the designed nickel-based catalyst is 3 orders of magnitude lower than that of the PGM catalyst.

[0032] According to an exemplary embodiment of the present invention, the present invention provides a method for synthesizing a nickel-based non-precious metal catalyst, comprising operations S1 to S3.

[0033] In operation S1, a non-precious metal salt solution is mixed with a molybdate solution to obtain an amorphous precursor after ultrasonication, wherein the non-precious metal salt solution includes a nickel salt solution.

[0034] In some embodiments, the molar ratio of the non-precious metal ions in the non-precious metal salt solution to the molybdate ions in the molybdate salt solution is 1: 1. According to experimental experience and theoretical calculations, a molar ratio of the non-precious metal ions to the molybdate ions of 1: 1 can exhibit good HER / HOR performance, which is required for hydrogen electrodes.

[0035] In some embodiments, the non-precious metal salt solution further comprises one or more of a cobalt salt solution, a chromium salt solution, and an iron salt solution.

[0036] In some embodiments, the nickel salt solution includes nickel chloride.

[0037] In some embodiments, the cobalt salt solution includes cobalt chloride.

[0038] In some embodiments, the chromium salt solution includes chromium chloride.

[0039] In some embodiments, the iron salt solution includes ferric chloride.

[0040] According to an embodiment of the present invention, by adding more than 1M non-metal ions (such as Ni 2+ 、Co 2+ Cr 2+ etc.) with MoO4 2- Mix so that the power product of their ion concentrations is greater than the solubility product constant, and the amorphous precursor in the solution will precipitate.

[0041] It should be noted that increasing the feed amount can produce amorphous precursors on a large scale, which is conducive to large-scale commercial applications.

[0042] In operation S2, after annealing in air or an inert atmosphere, the amorphous precursor is transformed into a crystalline intermediate.

[0043] In some embodiments, the annealing temperature in air or inert atmosphere is any value between 300°C and 600°C, for example, 300°C, 400°C, 500°C, 550°C, 600°C, but not limited to the values ​​listed, preferably 400°C.

[0044] In operation S3, the crystalline intermediate is reduced in a H2 / Ar mixed gas to obtain a nickel-based non-precious metal catalyst.

[0045] In some embodiments, the reduction temperature in the H2 / Ar mixed gas is any value between 300°C and 600°C, for example, 300°C, 400°C, 500°C, 550°C, 600°C, but not limited to the values ​​listed, and preferably 400°C.

[0046] In some embodiments, a total amount of 10 mmol of nickel chloride, cobalt chloride, and cadmium chloride is dissolved in 10 ml of deionized water to form a mixed solution; 10 mmol of sodium molybdate is dissolved in 10 ml of deionized water and stirred until dissolved. The sodium molybdate solution is quickly added to the mixed solution under ultrasound, and the amorphous precursors NiMoO4, CoMoO4, CdMoO4, etc. are completely precipitated after ultrasound for 1 minute. The precursor is collected by centrifugation and freeze-dried. It is then washed several times with ethanol and placed in a vacuum oven at 60°C for 12 hours. The dried amorphous precursor is heated at 400°C for 2 hours in an air atmosphere. This step converts the amorphous precursor into a crystalline intermediate. The obtained crystalline intermediate is then heated at 400°C for 2 hours in a 5% H2 / Ar atmosphere to obtain a nickel-based non-precious metal catalyst (NiCoCd / MoO2).

[0047] According to an exemplary embodiment of the present invention, the present invention provides a method for preparing a hydrogen electrode for a nickel-hydrogen secondary battery, comprising: operations S01 to S03.

[0048] Operation S01, preparing the above-mentioned nickel-based non-precious metal catalyst.

[0049] In operation S02, a nickel-based non-precious metal catalyst, a binder and a solvent are mixed to form a slurry.

[0050] In some embodiments, the binder includes one or more of polyvinylidene fluoride (PVDF), perfluorosulfonic acid polymer solution (Nafion), styrene butadiene rubber (SBR) emulsion, carboxymethyl cellulose (CMC), polyacrylic acid (PAA), polyacrylonitrile (PAN), and polyacrylate.

[0051] In some embodiments, the solvent includes water or an alcohol.

[0052] In some embodiments, the mass fraction of the nickel-based non-precious metal catalyst in the slurry is any value in the range of 0.1% to 50%, for example, 0.1%, 1%, 5%, 20%, 50%, but not limited to the values ​​cited. If the mass fraction of the nickel-based non-precious metal catalyst in the slurry is too small (less than 0.1%), the slurry will be too thin, making spraying difficult; if the mass fraction of the nickel-based non-precious metal catalyst in the slurry is 0.1% to 50%, the nickel-based non-precious metal catalyst can be evenly dispersed, which is conducive to the preparation of the hydrogen electrode.

[0053] In some embodiments, the mass fraction of the binder in the slurry is any value between 0.001% and 1%, for example, 0.001%, 0.01%, 0.1%, 0.5%, and 1%, but is not limited to the values ​​cited. It should be noted that the higher the mass fraction of the binder, the better the bonding effect, but at the same time it will lead to a decrease in electrode conductivity. The mass fraction of the binder in the slurry is 0.001% to 1%, which can achieve a good bonding effect while ensuring conductivity.

[0054] In operation S03, the slurry is sprayed on a gas diffusion electrode, and a hydrogen electrode is obtained after vacuum drying.

[0055] In some embodiments, the gas diffusion electrode is a nickel foam with a porous structure, wherein the nickel foam is used for conducting electricity, and the porous structure of the nickel foam is used for the transmission of H2.

[0056] In some embodiments, the drying temperature of vacuum drying is any value between 30°C and 90°C, such as 30°C, 50°C, 60°C, 80°C, and 90°C, but not limited to the values ​​cited; the drying time is any value between 1min and 1000min, such as 1min, 10min, 100min, 500min, and 1000min, but not limited to the values ​​cited. Too high a temperature (greater than 90°C) will cause deformation of the material and accelerate oxidation when it is taken out, thereby reducing the catalytic activity.

[0057] According to an exemplary embodiment of the present invention, the present invention provides a hydrogen electrode prepared by the above preparation method.

[0058] Figure 1 A schematic diagram of a nickel-hydrogen secondary battery provided in an embodiment of the present invention.

[0059] According to an exemplary embodiment of the present invention, the present invention provides a nickel-hydrogen secondary battery, referring to Figure 1 As shown, including:

[0060] A separator 1 including an electrolyte;

[0061] A positive electrode 2, comprising nickel hydroxide, adapted to perform a redox reaction between nickel hydroxide and nickel oxyhydroxide at an interface between the positive electrode 2 and the electrolyte;

[0062] The negative electrode 3, including the hydrogen electrode prepared as described above, is suitable for performing a redox reaction between H2O and gaseous H2 at the interface between the negative electrode 3 and the electrolyte.

[0063] In some embodiments, the electrolyte includes a potassium hydroxide aqueous solution or a sodium hydroxide aqueous solution; the concentration of the potassium hydroxide aqueous solution or the sodium hydroxide aqueous solution is 5 wt % to 30 wt %.

[0064] In some embodiments, the electrolyte is preferably a 26 wt % potassium hydroxide solution.

[0065] According to an embodiment of the present invention, the diaphragm of the nickel-hydrogen secondary battery is disposed between the positive electrode 2 and the negative electrode 3, and is suitable for preventing a short circuit between the positive and negative electrodes and allowing ions in the electrolyte to pass freely between the positive and negative electrodes. The electrolyte is attached to the diaphragm, forming a diaphragm 1 including the electrolyte.

[0066] According to an embodiment of the present invention, the nickel hydroxide at the positive electrode can undergo a conversion reaction between Ni(OH)2 and NiOOH, and the negative electrode undergoes hydrogen evolution and hydrogen oxidation reactions. Specifically, during charging, the water in the electrolyte is reduced to H2 on the surface of the negative electrode catalyst, and the nickel hydroxide at the positive electrode is oxidized to NiOOH, while during discharge, the H2 in the battery cavity is oxidized to water, and the nickel oxyhydroxide at the positive electrode is reduced to Ni(OH)2. This process is reversible, allowing the battery to be charged and discharged for multiple cycles without failure.

[0067] The following schematically illustrates the synthesis method of the designed nickel-based non-precious metal catalyst, the hydrogen electrode and its preparation method, and the nickel-hydrogen secondary battery. It should be noted that the example is only a specific embodiment of the present invention and cannot limit the protection scope of the present invention.

[0068] Example 1

[0069] Synthesis of nickel-based non-precious metal catalysts. Specifically, 10 mmol of nickel chloride was dissolved in 10 ml of deionized water to form a nickel salt solution; 10 mmol of sodium molybdate was dissolved in 10 ml of deionized water and stirred until dissolved. The sodium molybdate solution was quickly added to the nickel salt solution under ultrasound, and the amorphous precursor NiMoO4 was completely precipitated after ultrasound for 1 min. The precursor was collected by centrifugation and freeze-dried. It was then washed with ethanol several times and placed in a vacuum oven at 60°C for 12 hours. The dried amorphous precursor was heated at 400°C for 2 hours in an air atmosphere. This step converted the amorphous precursor into a crystalline intermediate. The obtained crystalline intermediate was then heated at 400°C for 2 hours in a 5% H2 / Ar atmosphere to obtain a nickel-based non-precious metal catalyst (Ni / MoO2). The prepared nickel-based non-precious metal catalyst was stored in a glove box to prevent any possible oxidation.

[0070] Figure 2 This is the XRD spectrum of the nickel-based non-precious metal catalyst Ni / MoO2 provided in Example 1 of the present invention.

[0071] The prepared nickel-based non-precious metal catalyst was subjected to XRD test. Figure 2 As shown, the test results show that the prepared nickel-based non-precious metal catalyst includes Ni / MoO2.

[0072] The hydrogen electrode was prepared. Specifically, 100 mg Ni / MoO2 and 50 μL Nafion solution were dispersed in 3 ml isopropanol solution to prepare a slurry, and then the slurry was drop-coated on a carbon felt with a thickness of 1 mm. The catalyst loading was 10 mg cm -2 .

[0073] A hydrogen electrode symmetrical battery was prepared. Specifically, the outer shell was a sealed container made of stainless steel, which was used to fill and seal high-pressure hydrogen. Both electrodes of the battery stack were prepared hydrogen electrodes, and the two electrodes were separated by a diaphragm material. The electrolyte was a 26wt% potassium hydroxide solution.

[0074] Figure 3 Polarization curve and stability test diagram of the hydrogen electrode provided in Example 1 of the present invention in the hydrogen redox reaction catalytic test at 26%wt KOH vs. reversible hydrogen standard potential.

[0075] The polarization performance of the prepared hydrogen electrode was tested at room temperature using a hydrogen electrode symmetric cell. Figure 3 As shown, the electrode polarization is at 20 mA cm -2 At a current density of 1.5 Å, the overpotential is ~100 mV, and the polarization remains stable after nearly 1200 hours of testing. This shows that the prepared hydrogen electrode has good polarization performance and long-term stability.

[0076] Example 2

[0077] The process of synthesizing the nickel-based non-precious metal catalyst is the same as that in Example 1.

[0078] The hydrogen electrode was prepared. Specifically, 100 mg Ni / MoO2 and 50 μL Nafion solution were dispersed in 3 ml isopropanol solution to prepare a slurry, and then the slurry was sprayed on one side of a 1 mm thick nickel foam. The sprayed side was the catalyst layer, and the unsprayed side was the gas diffusion layer. The catalyst loading was 10 mg cm -2 .

[0079] A nickel-hydrogen secondary battery is prepared. Specifically, the outer shell is a sealed container made of stainless steel, which is used to fill and seal high-pressure hydrogen. The battery stack is composed of a nickel hydroxide positive electrode and a prepared hydrogen electrode negative electrode, and the positive and negative electrodes are separated by a diaphragm material. The electrolyte is the potassium hydroxide solution configured as above.

[0080] The electrochemical performance of the prepared nickel-hydrogen secondary battery was tested at room temperature. The discharge capacity can reach 15 mAh / cm 2 .

[0081] Figure 4The charge and discharge curves of a nickel-hydrogen secondary battery assembled with the hydrogen electrode provided in Example 2 of the present invention as the negative electrode at different current densities.

[0082] refer to Figure 4 As shown, at 3 mA cm -2 ~7.5 mA cm -2 At the current density, the energy efficiency of nickel-hydrogen secondary batteries can still reach over 80%.

[0083] Figure 5 The nickel-hydrogen secondary battery assembled with the hydrogen electrode provided in Example 2 of the present invention as the negative electrode is 7.5 mA / cm 2 Figure 3 shows the cycling performance test results at current density of .

[0084] like Figure 5 As shown, the discharge capacity of the battery can reach 15 mAh cm -2 , at 7.5 mA cm at 100% DoD (depth of discharge) -2 The current density was stably cycled for 200 times without any capacity decay.

[0085] Comparative Example 1

[0086] A nickel-hydrogen secondary battery (Ni-H2 (Pt / C@GDL) battery) was assembled with a commercial catalytic electrode Pt / C@GDL as the negative electrode, and the electrochemical performance of the Ni-H2 (Pt / C@GDL) battery was tested. The Pt loading in the Pt / C catalyst was 20 μg cm -2 .

[0087] Figure 6 The nickel-hydrogen secondary battery (Ni-H2 (Pt / C@GDL) battery) assembled with the commercial catalytic electrode Pt / C@GDL as the negative electrode in Comparative Example 1 and the nickel-hydrogen secondary battery assembled with the hydrogen electrode provided in Example 2 of the present invention as the negative electrode were respectively -2 Charge and discharge curves at current density.

[0088] The electrochemical performance of the nickel-hydrogen secondary battery prepared by the hydrogen electrode of Example 2 of the present invention is compared with that of the nickel-hydrogen secondary battery of Comparative Example 1. Figure 6As shown, the energy efficiency of the nickel-hydrogen secondary battery of Example 2 of the present invention is significantly better than the energy density of the Ni-H2 (Pt / C@GDL) battery of Comparative Example 1. The nickel-hydrogen secondary battery provided by the present invention can achieve an energy density similar to or better than that of a nickel-hydrogen secondary battery assembled with Pt / C@GDL as the negative electrode, and can also reduce the cost of preparing the nickel-hydrogen secondary battery, wherein the cost of the hydrogen electrode provided by the present invention is at least one order of magnitude lower than that of Pt / C@GDL.

[0089] Example 3

[0090] The process of synthesizing the nickel-based non-precious metal catalyst is the same as that in Example 1, except that the prepared nickel-based non-precious metal catalyst is NiCo / MoO2.

[0091] The hydrogen electrode was prepared. Specifically, 100 mg NiCo / MoO2 and 50 μL Nafion solution were dispersed in 3 ml isopropanol solution to prepare a slurry, which was then sprayed on one side of a 1 mm thick nickel foam. The sprayed side was the catalyst layer, and the unsprayed side was the gas diffusion layer. The catalyst loading was 10 mg cm -2 .

[0092] A nickel-hydrogen secondary battery was prepared. Specifically, the outer shell was a sealed container made of stainless steel, which was used to fill and seal high-pressure hydrogen. The battery stack consisted of a nickel hydroxide positive electrode and a prepared hydrogen electrode negative electrode, and the positive and negative electrodes were separated by a diaphragm material. The electrolyte was a 26wt% potassium hydroxide solution.

[0093] Figure 7 The charge and discharge curves of a nickel-hydrogen secondary battery assembled with the hydrogen electrode provided in Example 3 of the present invention as the negative electrode at different current densities.

[0094] The electrochemical performance of the prepared battery was tested at room temperature. Figure 7 As shown, at 1.5 mA cm -2 -5 mAcm -2 At the current density, the battery energy efficiency can still reach over 80%.

[0095] Example 4

[0096] The process of synthesizing the nickel-based non-precious metal catalyst is the same as that in Example 1, except that the prepared nickel-based non-precious metal catalyst is NiCd / MoO2.

[0097] The hydrogen electrode was prepared. Specifically, 100 mg NiCd / MoO2 and 50 μL Nafion solution were dispersed in 3 ml isopropanol solution to prepare a slurry, which was then sprayed on one side of a 1 mm thick nickel foam. The sprayed side was the catalyst layer, and the unsprayed side was the gas diffusion layer. The catalyst loading was 10 mg cm -2 .

[0098] A nickel-hydrogen secondary battery was prepared. Specifically, the outer shell was a sealed container made of stainless steel, which was used to fill and seal high-pressure hydrogen. The battery stack consisted of a nickel hydroxide positive electrode and a prepared hydrogen electrode negative electrode, and the positive and negative electrodes were separated by a diaphragm material. The electrolyte was a 26wt% potassium hydroxide solution.

[0099] Figure 8 The charge and discharge curves of a nickel-hydrogen secondary battery assembled with the hydrogen electrode provided in Example 4 of the present invention as the negative electrode at different current densities.

[0100] The electrochemical performance of the prepared battery was tested at room temperature. Figure 8 As shown, at 1.5 mA cm -2 -5 mAcm -2 At the current density, the battery energy efficiency can still reach over 80%.

[0101] Example 5

[0102] The process of synthesizing the nickel-based non-precious metal catalyst is the same as that in Example 1, except that the prepared nickel-based non-precious metal catalyst is NiFe / MoO2.

[0103] The hydrogen electrode was prepared. Specifically, 100 mg NiFe / MoO2 and 50 μL Nafion solution were dispersed in 3 ml isopropanol solution to prepare a slurry, which was then sprayed on one side of a 1 mm thick nickel foam. The sprayed side was the catalyst layer, and the unsprayed side was the gas diffusion layer. The catalyst loading was 10 mg cm -2 .

[0104] A nickel-hydrogen secondary battery was prepared. Specifically, the outer shell was a sealed container made of stainless steel, which was used to fill and seal high-pressure hydrogen. The battery stack consisted of a nickel hydroxide positive electrode and a prepared hydrogen electrode negative electrode, and the positive and negative electrodes were separated by a diaphragm material. The electrolyte was a 26wt% potassium hydroxide solution.

[0105] Fig. 9 The charge and discharge curves of a nickel-hydrogen secondary battery assembled with the hydrogen electrode provided in Example 5 of the present invention as the negative electrode at different current densities.

[0106] The electrochemical performance of the prepared battery was tested at room temperature. Fig. 9As shown, at 1.5 mA cm -2 ~5 mAcm -2 At the current density, the battery energy efficiency can still reach over 80%.

[0107] The ordinal numbers used in the specification and claims, such as "first", "second", "third", etc., to modify the corresponding elements, do not themselves mean that the elements have any ordinal numbers, nor do they represent the order of one element and another element, or the order in the manufacturing method. The use of these ordinal numbers is only used to clearly distinguish a component with a certain name from another component with the same name.

[0108] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for synthesizing a nickel-based non-precious metal catalyst, characterized in that: include: Mixing a non-noble metal salt solution with a molybdate solution to obtain an amorphous precursor after ultrasonication, wherein the non-noble metal salt solution includes a nickel salt solution; After annealing in air or an inert atmosphere, the amorphous precursor is transformed into a crystalline intermediate; and In a H2 / Ar mixed gas, the crystalline intermediate is reduced to obtain a nickel-based non-precious metal catalyst.

2. The synthesis method according to claim 1, characterized in that The molar ratio of the non-precious metal ions in the non-precious metal salt solution to the molybdate ions in the molybdate solution is 1:

1.

3. The synthesis method according to claim 1, characterized in that The non-precious metal salt solution also includes one or more of a cobalt salt solution, a chromium salt solution and an iron salt solution.

4. The synthesis method according to claim 1, characterized in that The annealing temperature for annealing in air or inert atmosphere is 300℃~600℃; The reduction temperature in H2 / Ar mixed gas is 300℃~600℃.

5. A method for preparing a hydrogen electrode for a nickel-hydrogen secondary battery, characterized in that: include: The nickel-based non-precious metal catalyst is prepared by the synthesis method according to any one of claims 1 to 4; The nickel-based non-precious metal catalyst, a binder and a solvent are mixed to form a slurry; as well as The slurry is sprayed on a gas diffusion electrode, and a hydrogen electrode is obtained after vacuum drying.

6. The preparation method according to claim 5, characterized in that: The binder includes one or more of polyvinylidene fluoride, perfluorosulfonic acid type polymer solution, styrene-butadiene rubber emulsion, carboxymethyl cellulose, polyacrylic acid, polyacrylonitrile and polyacrylate; Solvents include water or alcohols; Preferably, the mass fraction of the nickel-based non-precious metal catalyst in the slurry is 0.1% to 50%; The mass fraction of the binder in the slurry is 0.001% to 1%.

7. The preparation method according to claim 5, characterized in that: The gas diffusion electrode is nickel foam with a porous structure.

8. The preparation method according to claim 5, characterized in that: The drying temperature of vacuum drying is 30℃~90℃, and the drying time is 1min~1000min.

9. A hydrogen electrode prepared by the preparation method according to any one of claims 5 to 8.

10. A nickel-hydrogen secondary battery, characterized in that: include: Electrolyte; The positive electrode (2) comprises nickel hydroxide and is suitable for performing a redox reaction between nickel hydroxide and nickel oxyhydroxide at the interface between the positive electrode (2) and the electrolyte; as well as The negative electrode (3) comprises the hydrogen electrode as claimed in claim 9, and is suitable for performing a redox reaction between H2O and gaseous H2 at the interface between the negative electrode (3) and the electrolyte.

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