A method for preparing a low-cost, highly catalytically active aluminum-air battery cathode catalyst

Abstract

This invention relates to a low-cost, highly catalytically active cathode catalyst preparation method for aluminum-air batteries. The method involves mixing and dissolving a Co-source compound, a Mn-source compound, a C-source compound, and a solvent in a specific ratio to obtain a reaction solution. A complexing agent is added to the reaction solution and mixed thoroughly. A precipitant is then added for a hydrothermal reaction, resulting in a precursor slurry. The precursor slurry is then filtered, washed, dried, ball-milled, and sieved to obtain a precursor powder. The precursor powder is calcined and then naturally cooled to obtain the final product. The Co-Mn bimetallic oxide composite carbon-based catalyst of this invention exhibits superior oxygen reduction performance, and aluminum-air batteries prepared using this catalyst achieve performance at a current density of 275 mA / cm². 2 During discharge, the maximum power density can reach 255.5 mW / cm². 2 .

Description

Technical Field

[0001] This invention belongs to the field of aluminum-air batteries, specifically relating to a method for preparing a low-cost, highly catalytically active cathode catalyst for aluminum-air batteries. Background Technology

[0002] Energy technology is a strategic high ground that countries around the world are vying for, serving as the "lifeblood," "lifeline," and "weapon" of national economies and national defense. With the increasingly severe global energy and environmental problems, my country has timely proposed a development strategy of "peak carbon and carbon neutrality." Developing fuel cell systems is one of the important measures to achieve this "dual carbon" goal. Aluminum-air fuel cells consume only metallic aluminum and oxygen in their power generation process, offering advantages such as low cost, non-toxicity, no pollution, stable discharge voltage, high specific energy, and high specific power.

[0003] The oxygen reduction performance of air electrode catalysts is crucial to the industrial application of aluminum-air batteries. Traditional precious metal platinum-carbon catalysts are scarce and expensive, and are prone to poisoning in alkaline electrolyte environments, leading to performance degradation and affecting service life. Developing a low-cost catalyst material with simple production process and high oxygen reduction activity is currently a research focus.

[0004] This invention discloses a carbon-based catalyst of Co-Mn bimetallic composite oxide and its preparation method. The raw materials are inexpensive, the production process is simple, and the catalytic activity is excellent, making it a very promising air cathode catalyst material for aluminum-air batteries. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and address the problem of insufficient oxygen reduction performance of existing aluminum-air battery cathode catalysts by providing a Co-Mn bimetallic oxide composite carbon-based catalyst, which is a low-cost and highly catalytically active aluminum-air battery cathode catalyst.

[0006] The present invention also provides a method for preparing the above-mentioned low-cost, high-catalytic-activity aluminum-air battery cathode catalyst, which has a simple synthesis process and produces a catalyst with excellent catalytic performance.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for preparing a low-cost, highly catalytically active aluminum-air battery cathode catalyst, comprising the following steps:

[0009] 1) Mix and dissolve the Co-source compound, Mn-source compound, C-source compound, and solvent in a certain proportion to obtain a reaction solution;

[0010] 2) Add a complexing agent to the reaction solution and mix it by ultrasonic stirring; then slowly add a precipitant to carry out a hydrothermal reaction. After the reaction is completed, the precursor slurry is obtained.

[0011] 3) The precursor slurry is filtered, washed, dried, ball-milled and sieved to obtain precursor powder; after calcination, the precursor powder is naturally cooled to obtain Co and Mn bimetallic oxide composite carbon-based catalyst.

[0012] Specifically, in step 1), the Co source compound is selected from cobalt nitrate and / or cobalt acetate.

[0013] Specifically, in step 1), the Mn source compound is selected from manganese nitrate and / or manganese acetate; the molar ratio of the Co source compound to the Mn source compound is 1:5 to 5:1.

[0014] Furthermore, in step 1), the C source is one or more of activated carbon, acetylene black, carbon nanotubes, and graphene, and the mass of the carbon source accounts for 20% to 80% of the sum of the masses of the Co source compound, the Mn source compound, and the C source. The solvent is deionized water or anhydrous ethanol.

[0015] Specifically, in step 2), the complexing agent is one or more of urea, ammonium bicarbonate, and melamine. After adding the complexing agent, the ultrasonic stirring time should preferably be 0.5 to 40 hours. The ratio of the amount of complexing agent added to the sum of the molar amounts of the cobalt source and manganese source compounds is 2:1 to 5:1.

[0016] Further, in step 2), the precipitant is sodium hydroxide or ammonia solution with a mass fraction of 25%. The ratio of the amount of precipitant added to the sum of the molar amounts of the cobalt source and manganese source compounds is 3:1 to 5:1. Specifically, in step 2), the hydrothermal reaction temperature is 50 to 100°C, and the hydrothermal reaction time is 1 to 10 hours.

[0017] Furthermore, in step 3), the filtration time is 30–300 min; the washing solution used is deionized water or anhydrous ethanol, and the number of washing cycles is 0–5; the drying temperature is 50–150℃, and the drying time is 10–300 min; the ball milling time is 5–300 min (preferably 10–120 min). The calcination temperature is 300–800℃, and the calcination time is 50–500 min.

[0018] This invention provides a low-cost, highly catalytically active aluminum-air battery cathode catalyst prepared by the above-described method.

[0019] The present invention also provides an aluminum-air battery, wherein the cathode of the aluminum-air battery comprises the above-described catalyst.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1) The catalyst of this invention has a simple synthesis process and uses inexpensive raw materials, Co and Mn source compounds, which have advantages for industrial production and are conducive to the commercial application of aluminum-air batteries.

[0022] 2) The Co / Mn bimetallic oxide composite carbon-based catalyst of this invention exhibits superior oxygen reduction performance, and the aluminum-air battery prepared using it performs well at a current density of 275 mA / cm². 2 During discharge, the maximum power density can reach 255.5 mW / cm². 2 . Attached Figure Description

[0023] Figure 1 The XRD pattern of the catalyst prepared in Example 1 of this invention;

[0024] Figure 2 The image shown is an electron microscope image of the catalyst prepared in Example 1 of this invention.

[0025] Figure 3 The voltage and power density curves are shown under different current densities during discharge. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] In the embodiments, all raw materials used were common commercially available products that can be directly purchased in the art. The ammonia solution used was 25% by mass.

[0028] Example 1

[0029] A method for preparing a low-cost, highly catalytically active aluminum-air battery cathode catalyst, comprising the following steps:

[0030] 1) Take 3g (0.016mol) cobalt nitrate, 14g (0.0784mol) manganese nitrate, and 5g activated carbon, add them to 10ml of deionized water and mix to dissolve, thus obtaining the reaction solution;

[0031] 2) Add 23g (0.383mol) of urea complexing agent to the reaction solution, stir ultrasonically for 1h to complex, then slowly add 26g (0.382mol) of ammonia water as a precipitant, and react in a 50℃ water bath with ultrasonic stirring for 120min. After the reaction is completed, the precursor slurry is obtained.

[0032] 3) The precursor slurry was filtered, then washed with deionized water, filtered again, and then dried in an oven at 80°C for 200 min. The dried solid was transferred to a ball mill and ball-milled for 60 min. After sieving, it was placed in a crucible and calcined in a muffle furnace at 500°C for 1 h. After natural cooling, the carbon-based catalyst of Co-Mn bimetallic oxide was obtained.

[0033] Example 2

[0034] A method for preparing a low-cost, highly catalytically active aluminum-air battery cathode catalyst, comprising the following steps:

[0035] 1) Take 1.5g (0.008mol) cobalt acetate, 1g (0.004mol) manganese acetate, and 10g graphene, add them to 20ml of anhydrous ethanol and mix to dissolve, to obtain the reaction solution;

[0036] 2) Add 4g (0.051mol) of ammonium bicarbonate to the reaction solution as a complexing agent, stir ultrasonically for 2h to complex, then slowly add 2g of sodium hydroxide as a precipitant, react in a 90℃ water bath for 150min, and the precursor slurry is obtained after the reaction is completed.

[0037] 3) The precursor slurry was filtered, then washed with anhydrous ethanol, filtered twice more, and then dried in an oven at 150°C for 60 min. The dried solid was transferred to a ball mill and ball-milled for 10 min. After sieving, it was placed in a crucible and calcined in a muffle furnace at 300°C for 5 h. After natural cooling, a carbon-based catalyst of Co-Mn bimetallic oxide was obtained.

[0038] Example 3

[0039] A method for preparing a low-cost, highly catalytically active aluminum-air battery cathode catalyst, comprising the following steps:

[0040] 1) Take 10g (0.053mol) cobalt acetate, 2g (0.011mol) manganese nitrate, and 12g carbon nanotubes, add them to 20ml of anhydrous ethanol and mix to dissolve, thus obtaining the reaction solution;

[0041] 2) Add 16g of melamine to the reaction solution as a complexing agent, stir ultrasonically for 2h to complex, then slowly add 8g of sodium hydroxide as a precipitant, react in a 70℃ water bath for 10h, and the precursor slurry is obtained after the reaction is completed.

[0042] 3) The precursor slurry was filtered, then washed with anhydrous ethanol, filtered twice more, and then dried in an oven at 150°C for 60 min. The dried solid was transferred to a ball mill and ball-milled for 10 min. After sieving, it was placed in a crucible and calcined in a muffle furnace at 800°C for 1 h. After natural cooling, a carbon-based catalyst of Co-Mn bimetallic oxide was obtained.

[0043] Figure 1 The XRD pattern of the catalyst (Co-Mn / CNts) prepared in Example 1 of this invention is shown. Crystal form confirmation reveals that the main component of this catalyst is (Co, Mn)(Co, Mn)₂O₄, therefore we obtained a Co-Mn bimetallic oxide catalyst.

[0044] Figure 2 Electron microscopy (EM) images of the catalyst prepared in Example 1 of this invention are provided. The EEM images of the catalyst show that the catalyst particles are very fine, ranging from 20 to 80 nanometers, and the particles are uniformly attached to the carbon matrix.

[0045] Aluminum-air battery application test:

[0046] The catalyst prepared in Example 1 was mixed with binder PTFE at a mass ratio of 2:1 and then rolled repeatedly to prepare a catalytic membrane with a thickness of 0.3 mm. The membrane was then combined with a waterproof and breathable membrane and a copper mesh current collector to form an air electrode. A 6 mol / L KOH solution was used as the electrolyte and pure aluminum was used as the anode. Discharge was carried out at different current densities. Figure 3 Voltage and power density curves under different current densities are presented. Figure 3 The discharge results show that the battery operates at a current density of 275 mA / cm². 2 During discharge, the maximum power density can reach 255.5 mW / cm². 2 It has excellent oxygen reduction performance.

Claims

1. A method for preparing a low-cost, highly catalytically active aluminum-air battery cathode catalyst, characterized in that, Includes the following steps: 1) Mix and dissolve the Co-source compound, Mn-source compound, C-source compound, and solvent in a certain proportion to obtain a reaction solution; 2) Add a complexing agent to the reaction solution and mix well; then add a precipitant to carry out a hydrothermal reaction. After the reaction is completed, the precursor slurry is obtained. 3) The precursor slurry is filtered, washed, dried, ball-milled, and sieved to obtain precursor powder; The precursor powder is obtained by calcining and then naturally cooling. In step 1), the Co source compound is selected from cobalt nitrate and / or cobalt acetate; In step 1), the Mn source compound is selected from manganese nitrate and / or manganese acetate; the molar ratio of the Co source compound to the Mn source compound is 1:4.9; In step 2), the hydrothermal reaction temperature is 50–100℃, and the hydrothermal reaction time is 1–10 hours; The main components of the obtained catalyst are (Co, Mn)(Co, Mn)₂O₄; the catalyst particles are 20–80 nanometers in size; the obtained catalyst is used to prepare aluminum-air batteries, and the performance of the prepared aluminum-air batteries is as follows: current density 275 mA / cm². 2 During discharge, the maximum power density reaches 255.5 mW / cm². 2 .

2. The method for preparing the low-cost, highly catalytically active aluminum-air battery cathode catalyst as described in claim 1, characterized in that, In step 1), the C source is one or more of activated carbon, acetylene black, carbon nanotubes, and graphene, and the mass of the carbon source accounts for 20% to 80% of the sum of the mass of the Co source compound, the Mn source compound, and the C source.

3. The method for preparing the low-cost, highly catalytically active aluminum-air battery cathode catalyst as described in claim 1, characterized in that, In step 2), the complexing agent is one or more of urea, ammonium bicarbonate, and melamine; the ratio of the amount of complexing agent added to the sum of the molar amounts of the cobalt source and manganese source compounds is 2:1 to 5:

1.

4. The method for preparing the low-cost, highly catalytically active aluminum-air battery cathode catalyst as described in claim 1, characterized in that, In step 2), the precipitant is sodium hydroxide or ammonia; the ratio of the amount of precipitant added to the sum of the molar amounts of the cobalt source and manganese source compounds is 3:1 to 5:

1.

5. The method for preparing the low-cost, highly catalytically active aluminum-air battery cathode catalyst as described in claim 1, characterized in that, In step 3), the calcination temperature is 300–800℃ and the calcination time is 50–500 min.

6. A low-cost, highly catalytically active aluminum-air battery cathode catalyst prepared by any of the preparation methods described in claims 1 to 5.

7. An aluminum-air battery, characterized in that, The cathode of the aluminum-air battery comprises the catalyst of claim 6.

8. The application of the catalyst according to claim 6 in the preparation of aluminum-air batteries.

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