Carbon-loaded nickel sulfide catalyst as well as preparation method and application thereof

Abstract

The invention designs a carbon-loaded nickel sulfide catalyst with high energy density and long service life and a preparation method thereof, and belongs to the technical field of non-noble metal catalysts for zinc-air batteries. Nickel sulfide with a carbon source is introduced, so that a synthesis process is optimized, and the defect of poor cycling stability of the catalyst is overcome. The preparation method comprises the following steps: 1) preparing a Ni (OH) 2 precursor by a solvothermal method; 2) preparing nickel sulfide catalyst powder by a high-temperature calcination method; and 3) preparing the nickel sulfide catalyst pole piece. The nickel sulfide catalyst prepared by the method introduces a carbon source to relieve expansion of a sulfide catalyst, the oxygen reduction performance and the oxygen evolution performance are improved, the cycle stability of a sulfide catalyst zinc-air battery is greatly improved, the attenuation rate in the cycle process of the battery is slowed down, and wide application of a new air battery catalyst is facilitated.

Description

(I) Technical Field

[0001] This invention belongs to the field of non-precious metal catalysts for zinc-air batteries, specifically relating to a carbon-supported nickel sulfide catalyst and its preparation method. (II) Background Technology

[0002] Zinc-air batteries are a common type of primitive battery that generates electricity through a chemical reaction between zinc and air. This type of battery typically consists of a zinc negative electrode, an air positive electrode, and an electrolyte. In a zinc-air battery, zinc is oxidized into zinc ions, releasing electrons. These electrons flow through an external circuit, generating an electric current, and then return to the positive electrode of the battery, where they react with oxygen and water absorbed from the air to produce hydroxide ions, releasing electrons and ultimately forming water. Compared to other battery types, zinc-air batteries have several advantages, such as low cost, high energy density, and good safety. They are commonly used in applications requiring low-cost, high-performance power sources, such as disposable electronic devices, remote controls, and flashlights.

[0003] The oxygen reduction reaction (OER) and oxygen evolution reaction (OER) are key air-electrode catalytic reactions in zinc-air batteries (ZABs), and noble metal catalysts (platinum, iridium) play a crucial role in accelerating reaction kinetics. However, the high cost and scarcity of noble metal catalysts severely hinder their widespread application in emerging energy conversion devices. To overcome this challenge and promote the commercialization of ZABs and water electrolysis, many researchers have begun to focus on the research of non-noble metal catalysts, especially catalysts with nitrogen-sulfur coordinated transition metal atoms (such as nickel, cobalt, etc.) on carbon supports. Nickel sulfide catalysts, characterized by their good electronic conductivity, abundant active sites on the surface, and high chemical stability, have become a promising class of non-noble metal catalysts because they exhibit excellent performance in the OER process and can largely replace commercial IrO2.

[0004] However, non-precious metal catalysts still face significant challenges in practical applications: i) poor battery performance due to relatively low active site density (less than 3%) and poor contact with the three-phase interface (TPB); ii) poor durability due to dissolution and migration of active sites during harsh electrochemical processes.

[0005] Therefore, developing an ORR / OER catalyst that is simple to prepare, widely applicable, inexpensive, suitable for mass production, and exhibits excellent performance and stability in zinc-air is of great practical significance. (III) Summary of the Invention

[0006] Based on the background technology, in order to solve the above-mentioned technical problems, this invention proposes a carbon-supported nickel sulfide catalyst, its preparation method and application, which enhances the activity and stability of non-precious metal nickel sulfide catalyst by introducing sulfur and carbon support.

[0007] To achieve the above objectives, the present invention provides a method for preparing a carbon-supported nickel sulfide catalyst, characterized by comprising the following steps:

[0008] (1) Preparation of Ni(OH)2 precursor: Weigh out the corresponding stoichiometric amounts of Ni(OAc)2·4H2O and add them to a beaker. Measure deionized water into the beaker using a graduated cylinder and stir magnetically until completely dissolved. Then add ammonia to adjust the pH. Transfer the solution to a reaction vessel and carry out a hydrothermal reaction, followed by washing and drying to obtain the precursor.

[0009] (2) Preparation of nickel sulfide catalyst powder: The Ni(OH)2 precursor and sulfur powder prepared in step (1) were placed upstream and downstream of a quartz tube, respectively. The nickel sulfide catalyst powder was obtained by heating and holding in a tube furnace.

[0010] (3) Preparation of nickel sulfide catalyst electrode: Weigh nickel sulfide, Super-P and PVDF in a certain proportion and grind them evenly in a mortar. Mix them with NMP solvent to form a slurry and coat it on nickel foam. Transfer it to a vacuum oven to dry. Then cut it into an electrode with a diameter of 12 mm. Then attach an air diffusion layer to the back of the nickel foam and press it into a sheet. Finally, obtain the nickel sulfide catalyst electrode.

[0011] Preferably, the mass of Ni(OAc)2·4H2O in step (1) is 1.0g.

[0012] Preferably, the ammonia water described in step (1) is used to adjust the pH to 9-9.5.

[0013] Preferably, the hydrothermal reaction temperature in step (1) is 180°C, and the temperature is maintained for 12 hours, and then naturally cooled to room temperature.

[0014] Preferably, the cleaning in step (1) requires centrifugation three times each with deionized water and anhydrous ethanol, at 8000 rpm for 5 minutes, to remove residual impurities on the surface.

[0015] Preferably, the drying temperature in step (1) is 80°C, and the drying time is 12 hours in a forced-air drying oven.

[0016] Preferably, the ratio of Ni(OH)2 precursor to sulfur powder in step (2) is 1:7.

[0017] Preferably, the tubular furnace heating described in step (2) is carried out under argon protection.

[0018] Preferably, the heating program of the tubular furnace in step (2) is to heat from room temperature to 300°C at a rate of 5°C / min, and maintain the temperature at a flow rate of 30 sccm for 2 hours, and then allow it to cool naturally to room temperature.

[0019] Preferably, the loading of the nickel sulfide catalyst electrode in step (3) is 2.0–3.0 mg cm⁻¹. -2 .

[0020] Preferably, the ratio of nickel sulfide, Super-P, and PVDF in step (3) is 8:1:1.

[0021] Preferably, the vacuum oven drying temperature in step (3) is 60-80°C and the drying time is 12-24 hours.

[0022] Due to the adoption of the above technical solutions, the carbon-supported nickel sulfide of the present invention has the following characteristics:

[0023] (1) The introduction of nickel sulfide as a carbon source greatly improves the cycle stability of the catalyst and slows down the decay rate during the cycle.

[0024] (2) Using MOF as a precursor can help maintain the framework and facilitate subsequent ion transport.

[0025] (3) The carbon-supported nickel sulfide catalyst preparation method of the present invention is universal, simple to prepare, widely applicable, and inexpensive, and can be used for mass production.

[0026] The three characteristics mentioned above enable the prepared carbon-supported nickel sulfide to have more active sites and longer cycle life, playing a key role in the commercial development of oxygen evolution / zinc air battery catalysts. (iv) Description of the attached drawings

[0027] Figure 1 The image shows the surface SEM characterization of the carbon-supported nickel sulfide prepared in Example 1 of this invention.

[0028] Figure 2 The image shows the surface EDX characterization of the carbon-supported nickel sulfide prepared in Example 1 of this invention.

[0029] Figure 3 The image shows the XRD pattern of the carbon-supported nickel sulfide prepared in Example 1 of this invention.

[0030] Figure 4 The ORR linear cyclic voltammetry curve of the carbon-supported nickel sulfide prepared in Example 1 of this invention is shown.

[0031] Figure 5 The OER linear cyclic voltammetry curve of the carbon-supported nickel sulfide prepared in Example 1 of this invention is shown.

[0032] Figure 6 The AC impedance diagram of carbon-supported nickel sulfide prepared in Example 1 of the present invention at room temperature.

[0033] Figure 7 The energy density curve of the carbon-supported nickel sulfide catalyst prepared in Example 1 is shown.

[0034] Figure 8 Cyclic spectroscopy of the carbon-supported nickel sulfide catalyst prepared in Example 1 at 10 mA / cm². (V) Specific Implementation Methods

[0035] The present invention will be further described below with reference to specific embodiments.

[0036] Example 1

[0037] (1) Preparation of Ni(OH)2 precursor: 1.0 g Ni(OAc)2·4H2O was completely dissolved in deionized water (50 mL), and the pH of the solution was adjusted to 9-9.5 with ammonia. The mixed solution was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and heated at 180 °C for 12 h. After cooling the sample to room temperature, it was washed three times with deionized water and ethanol, and then dried in a vacuum drying oven at 60 °C for 12 h.

[0038] (2) Preparation of nickel sulfide catalyst powder: The Ni(OH)2 precursor and sulfur powder prepared in step (1) were placed at a mass ratio of 1:7 in the upstream and downstream of a quartz tube. The tube was heated to 300°C in an argon atmosphere at 5°C / min and held at an argon flow rate of 30 sccm for 2 hours, and then cooled to room temperature.

[0039] (3) Preparation of nickel sulfide catalyst electrode: Nickel sulfide, Super-P, and PVDF were weighed in a mortar and ground evenly in a ratio of 8:1:1. The mixture was then prepared into a slurry with NMP solvent and coated onto nickel foam. The slurry was then transferred to a vacuum oven and dried at 80°C for 12 hours. After surface drying at room temperature, the slurry was transferred to a vacuum oven and dried at 60°C for 12 hours. An air diffusion layer was then attached to the back of the nickel foam and the slurry was pressed into a sheet to obtain the nickel sulfide catalyst electrode.

[0040] Example 2

[0041] (1) Same as Example 1

[0042] (2) Preparation of nickel sulfide catalyst powder: The Ni(OH)2 precursor and sulfur powder prepared in step (1) were placed at a mass ratio of 1:7 upstream and downstream of a quartz tube. The tube was heated to 300°C in an argon atmosphere at 5°C / min and held at an argon flow rate of 30 sccm for 1 hour, and then cooled to room temperature.

[0043] (3) Same as Example 1.

[0044] Example 3

[0045] (1) Same as Example 1.

[0046] (2) Preparation of nickel sulfide catalyst powder: The Ni(OH)2 precursor and sulfur powder prepared in step (1) were placed at a mass ratio of 1:7 in the upstream and downstream of a quartz tube. The tube was heated to 300°C in an argon atmosphere at 5°C / min and held at an argon flow rate of 30 sccm for 3 hours, and then cooled to room temperature.

[0047] (3) Same as Example 1.

[0048] The application of a carbon-supported nickel sulfide catalyst of the present invention: as a catalyst for zinc-air batteries.

Claims

1. A method for preparing a carbon-supported nickel sulfide catalyst, the specific preparation method comprising the following steps: (1) Preparation of Ni(OH)2 precursor: Weigh out the corresponding stoichiometric amounts of Ni(OAc)2·4H2O and add them to a beaker. Measure deionized water into the beaker using a graduated cylinder and stir magnetically until completely dissolved. Then add ammonia to adjust the pH. Transfer the solution to a reaction vessel and carry out a hydrothermal reaction, followed by washing and drying to obtain the precursor. (2) Preparation of nickel sulfide catalyst powder: The Ni(OH)2 precursor and sulfur powder prepared in step (1) were placed upstream and downstream of a quartz tube, respectively. The nickel sulfide catalyst powder was obtained by heating and holding in a tube furnace. (3) Preparation of nickel sulfide catalyst electrode: Weigh nickel sulfide, Super-P and PVDF in a certain proportion and grind them evenly in a mortar. Mix them with NMP solvent to form a slurry and coat it on nickel foam. Transfer it to a vacuum oven to dry. Then cut it into an electrode with a diameter of 12 mm. Then attach an air diffusion layer to the back of the nickel foam and press it into a sheet. Finally, obtain the nickel sulfide catalyst electrode.

2. The method as described in claim 1, characterized in that: In step (1), the mass of Ni(OAc)2·4H2O is 1.0g.

3. The method as described in claim 1, characterized in that: In step (1), ammonia is used to adjust the pH to 9-9.

5.

4. The method as described in claim 1, characterized in that: In step (1), the hydrothermal reaction temperature is 180°C, and the temperature is maintained for 12 hours before naturally cooling to room temperature.

5. The method as described in claim 1, characterized in that: In step (2), the ratio of Ni(OH)2 precursor to sulfur powder is 1:

7.

6. The method as described in claim 1, characterized in that: In step (2), the heating program of the tubular furnace is 5℃ / min to raise the temperature from room temperature to 300℃, and maintain it at a flow rate of 30 sccm for 2 hours, and then let it cool naturally to room temperature.

7. The method as described in claim 1, characterized in that: In step (3), the loading of the nickel sulfide catalyst electrode is 2.0–3.0 mg cm⁻¹. -2 .

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