Coal gasification fine slag high-activity electrocatalyst material as well as preparation method and application thereof

Abstract

The invention discloses a coal gasification fine slag high-activity electrocatalyst material as well as a preparation method and application thereof, and relates to the technical field of solid waste resource utilization, the material is prepared by taking coal gasification fine slag as a raw material through alkali fusion activation, acid pickling impurity removal and solvothermal compound modification processes in sequence; the microstructure is a complex composed of a three-dimensional wrinkled needle-shaped framework and carbonaceous nanometer micro-pellets attached to the three-dimensional wrinkled needle-shaped framework, and molybdenum-based active components are loaded on the three-dimensional wrinkled needle-shaped framework. When the material is used as a positive electrode catalyst of a lithium air battery, the rate capability and the cycling stability of the battery can be remarkably improved. The method realizes high-value utilization of the industrial solid waste, is simple in process and low in cost, and has a wide application prospect in the fields of new energy storage and solid waste recycling.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, and in particular to highly active electrocatalyst materials for coal gasification fine slag, their preparation methods, and applications. Background Technology

[0002] Coal gasification technology, as one of the core pathways for the clean utilization of coal, plays a crucial role in my country's energy structure transformation. However, with the large-scale application of this technology, the generation of coal gasification slag, a solid byproduct, has increased dramatically. According to industry statistics, its annual emission growth rate has exceeded 15%, leading to a series of problems that cannot be ignored: the large accumulation of coal gasification slag not only results in the inefficient use of land resources but also poses a risk of heavy metal leaching pollution; furthermore, it negatively impacts the surrounding aquatic ecosystems and soil physicochemical properties, seriously threatening the regional ecological balance. This situation indicates that the harmless disposal and resource utilization of coal gasification slag has become a critical technological bottleneck that urgently needs to be overcome for the sustainable development of the coal industry.

[0003] With its ultra-high energy density of 3500Wh / kg, lithium-air batteries are considered a key breakthrough in resolving the conflict between energy demand and environmental protection, and have enormous potential to revolutionize the future energy storage field.

[0004] However, this technology currently faces bottlenecks in its industrialization: First, the oxygen reaction kinetics at the cathode are sluggish, limited by multiple factors such as low oxygen solubility in the electrolyte, hindered diffusion, insufficient catalyst activity, and material structure unfavorable to mass transfer, severely affecting battery cycle stability. Second, the lithium peroxide produced during discharge has poor conductivity, and byproducts such as lithium carbonate continuously accumulate on the electrode surface, leading to intensified polarization and rapid performance degradation of the battery. Current research focuses on developing high-performance non-precious metal catalysts, such as transition metal oxides and carbon-based composite materials, but challenges such as high cost, insufficient activity, or structural instability remain.

[0005] It is worth noting that coal gasification slag is rich in carbonaceous and aluminosilicate components, possessing potential value as a carbon-based catalytic support; while lithium-air battery cathodes urgently require low-cost, high-activity, and structurally stable catalytic materials. Theoretically, converting coal gasification slag into electrocatalysts could achieve the dual benefits of "waste treatment." However, no successful cases have been found in existing technologies. The fundamental reason is that coal gasification slag has a complex composition, dense structure, and low catalytic activity, making direct application difficult to meet the stringent requirements of battery materials for conductivity, active site density, and structural stability; traditional solid waste activation and catalytic material preparation processes are incompatible, lacking systematic structural reconstruction and activity regulation strategies. Therefore, developing an integrated technology that can simultaneously achieve high-value conversion of coal gasification slag and the construction of high-performance catalysts for lithium-air batteries has significant scientific and application value. Summary of the Invention

[0006] This application provides a highly active electrocatalyst material for coal gasification fine slag, its preparation method, and its application, which solves the problem of poor battery cycle stability in the prior art and achieves the goal of a more stable electrocatalyst material.

[0007] This application provides an embodiment for the preparation of a highly active electrocatalyst material for coal gasification fine slag, including the following steps: S1. Preparation of modified coal gasification fine slag: Coal gasification fine slag and sodium carbonate are mixed and ground in a mass ratio, and calcined at 800-900 degrees Celsius for 1-4 hours to obtain calcined fine slag; The calcined fine slag is mixed with a hydrofluoric acid solution with a mass concentration of 5-15% at a solid-liquid ratio of 0.25 g / ml, stirred at room temperature for 20-28 hours, and then washed and dried to obtain modified coal gasification fine slag; S2. Preparation of highly active electrocatalyst material: The modified coal gasification fine slag, ammonium molybdate, and anhydrous glucose are dissolved in deionized water, stirred evenly, and then transferred to a high-pressure reactor. The reaction is carried out at 160-200 degrees Celsius for 10-14 hours. The reaction product is washed and dried to obtain the highly active electrocatalyst material.

[0008] Furthermore, in step S1, the mass ratio of the coal gasification fine slag to sodium carbonate is 3:2.

[0009] Furthermore, in step S1, the calcination temperature is 875 degrees Celsius and the calcination time is 2.5 hours.

[0010] Furthermore, in step S2, the mass ratio of the modified coal gasification fine slag, ammonium molybdate, and anhydrous glucose is 1:2:0.6.

[0011] In a further step S2, the solvothermal reaction temperature is 180 degrees Celsius and the reaction time is 12 hours.

[0012] A highly active electrocatalyst material for coal gasification fine slag is prepared by the above-mentioned preparation method.

[0013] The above-mentioned highly active electrocatalyst material for coal gasification fine slag is used as a positive electrode electrocatalyst in lithium-air batteries.

[0014] Furthermore, the highly active electrocatalyst material is mixed with conductive carbon black and binder at a mass ratio of 7:2:1 to form a slurry, which is then coated onto a conductive current collector and dried to form the positive electrode of a lithium-air battery.

[0015] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: The successful conversion of coal gasification slag into highly active electrocatalyst material has enabled the resource utilization and high-value utilization of solid waste, effectively alleviating environmental pressure.

[0016] The prepared electrocatalyst material has a unique three-dimensional pleated needle-like and carbonaceous microsphere composite structure, which provides abundant active sites, facilitates oxygen adsorption, diffusion and ion transport, and significantly improves electrocatalytic activity.

[0017] When applied to the cathode of lithium-air batteries, the batteries exhibit excellent rate performance and long-cycle stability. The preparation method uses widely available raw materials, involves simple process steps, and is easy to control, demonstrating good technical feasibility and economic viability, and possessing potential for industrial application. This invention opens up a new path for green development in the coal industry by converting coal gasification slag into a highly active electrocatalyst material.

[0018] On the one hand, it realizes the transformation of coal gasification slag from industrial solid waste into high-value-added materials, effectively alleviating the environmental pressure caused by solid waste accumulation and aligning with my country's "dual carbon" strategic goals. On the other hand, systematic testing shows that compared with conventional unmodified coal gasification slag-based batteries, batteries prepared with this material show significant improvements in key electrochemical performance indicators such as charge-discharge efficiency and cycle stability, providing a practical and feasible technical solution for the high-value application of coal gasification slag.

[0019] This highly active electrocatalyst material and its preparation method have successfully overcome the dual technical bottlenecks of rapid performance degradation in lithium-air batteries and the difficulty in disposing of fine coal gasification slag. The preparation process employs a standardized procedure, utilizes widely available raw materials, and involves simple operation steps, combining technological innovation with economic feasibility. It demonstrates broad prospects for industrial application in the fields of new energy batteries and solid waste resource utilization. Attached Figure Description

[0020] Figure 1 This is a diagram illustrating the experimental steps of the present invention; Figure 2 XRD patterns of different materials used in this invention; Figure 3 This is a SEM image of the fine coal gasification residue from the present invention. Figure 4 This is a SEM image of the modified fine slag composite material of the present invention; Figure 5 This is a graph showing the rate performance results of the present invention; Figure 6 The graph shows the cyclic performance results of this invention. Detailed Implementation

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] Example 1: As Figure 1 A method for preparing a highly active electrocatalyst material for coal gasification fine slag; Specifically, it includes: S1. Preparation of modified coal gasification fine slag: Take about 100g of coal gasification slag and grind it with a ball mill until the particle size is ≤200μm to obtain coal gasification fine slag. Weigh 66.7g of sodium carbonate (i.e. 2 / 3 of the mass of fine slag), mix it with the fine slag, put it into a ball mill jar, and grind it for 15 minutes to obtain mixed powder.

[0023] The mixed powder was placed in a muffle furnace and calcined at 875°C for 2.5 hours. After natural cooling, calcined fine slag was obtained. 20g of calcined fine slag was weighed and 80g of hydrofluoric acid solution (mass concentration of 10%) was added. After stirring for 15 minutes, the mixture was placed on a magnetic stirrer and stirred at room temperature for 24 hours to obtain a mixed solution.

[0024] The mixed solution was centrifuged at 1100 rpm for 3 minutes, the supernatant was discarded, deionized water was added for washing, and centrifugation was repeated until the pH of the washing solution was 7. The solution was then washed once with anhydrous ethanol, and the solid was collected after centrifugation. The solid was placed in an oven at 60℃ and dried for 24 hours to obtain modified coal gasification fine slag.

[0025] S2. Preparation of highly active electrocatalyst materials: Weigh the following raw materials: modified coal gasification fine slag: 0.5g, ammonium molybdate tetrahydrate ((NH4)6Mo7O 24 ·4H2O): 1.0g, anhydrous glucose: 0.3g, deionized water: 50mL; After the above solid raw materials are mixed evenly, they are added to deionized water and stirred evenly. The mixture is then transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene and reacted at 180 °C for 12 hours. After the reaction is completed, the mixture is allowed to cool naturally. The product is then centrifuged (1100 rpm, 3 minutes), washed with water until neutral, and then washed once with anhydrous ethanol. The washed solid is then placed in a 60 °C oven and dried for 24 hours to obtain a black powdery high-activity electrocatalyst material (modified fine slag composite material).

[0026] The modified fine slag composite material, molybdenum oxide, and coal gasification fine slag were analyzed by XRD patterns, and the results are as follows: Figure 4As shown, the modified high-activity electrocatalyst material exhibits distinct static oxide characteristic peaks compared to the unmodified coal gasification fine slag, indicating the successful incorporation of molybdenum-based active components.

[0027] SEM analysis was performed on the modified fine slag composite material and coal gasification fine slag, and the results are as follows: Figure 2 , Figure 3 As shown, the surface of coal gasification fine slag exhibits diverse and uneven particle morphologies, including spheres of varying shapes and sizes, as well as obvious particle aggregates. The adhesion between these particles further exacerbates the agglomeration phenomenon, affecting its physicochemical properties. In contrast, the modified coal gasification fine slag material displays a unique three-dimensional wrinkled needle-like structure, beneath which are distributed nanospheres composed of purified carbonaceous materials from the coal gasification fine slag. These microspheres not only vary in size and shape but also possess excellent electrical conductivity and chemical stability, effectively promoting oxygen adsorption and diffusion, thereby significantly enhancing catalytic activity. After modification, the needle-like structure improves the interfacial contact between the modified fine slag and the electrolyte, enhancing ion transport efficiency. Furthermore, the presence of carbonaceous microspheres effectively inhibits the binding and stacking of the needle-like structure, ensuring sufficient exposure of active sites and laying a solid foundation for improving the energy storage performance of the fine slag.

[0028] Sodium carbonate was used as the primary modifier and first mixed with coal gasification fine slag through grinding to promote uniform mixing and subsequent reactions. The resulting powder mixture was then calcined, allowing it to undergo physical and chemical changes with sodium carbonate during alkali calcination. This optimized powder properties and improved its application value, yielding calcined fine slag. Reducing the amount of sodium carbonate resulted in incomplete aluminosilicate conversion and decreased catalytic activity; increasing the amount of sodium carbonate led to agglomeration during calcination, poor subsequent acid treatment, and a decrease in the material's specific surface area.

[0029] By using hydrofluoric acid solution as a second modifier, the calcined fine slag is dispersed in the hydrofluoric acid solution and subjected to magnetic stirring treatment, so that the hydrofluoric acid solution can fully contact the calcined fine slag, thereby achieving the purpose of further removing impurity metal elements from the calcined fine slag.

[0030] Finally, using modified coal gasification fine slag and molybdenum tetrahydrate as raw materials, and anhydrous glucose as a dispersant and structure directing agent, the modified coal gasification fine slag, molybdenum tetrahydrate and anhydrous glucose were mixed and dispersed in water for a solvothermal reaction. This allowed the modified coal gasification fine slag, molybdenum tetrahydrate and anhydrous glucose to undergo chemical changes in an aqueous solvent environment, thereby obtaining a highly active electrocatalyst material with amorphous oxide (disordered structure endows coal gasification fine slag with high surface activity and fast ion transport characteristics) as the main component.

[0031] Example 2: Example 1 provides a material with high electrocatalytic potential. This example describes its application in lithium-oxygen batteries.

[0032] The highly active electrocatalyst material prepared in Example 1, conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 7:2:1, and N-methylpyrrolidone (NMP) was added to form a slurry. The slurry was uniformly coated on carbon paper (0.2 mm thick) and vacuum dried at 80 °C for 12 hours to obtain the positive electrode sheet.

[0033] Assemble a CR2032 coin cell lithium-air battery with a 1M LiTFSI / TEGDME electrolyte and a lithium metal sheet as the negative electrode. Tests were conducted in an oxygen atmosphere. Rate performance: at 200mA g -1 500mA g -1 1000mA g -1 Its electrocatalytic performance was measured at current density to obtain rate performance as follows: Figure 5 As shown, the lithium-oxygen battery using a highly active electrocatalyst anode material made from modified coal gasification fine slag can achieve high-rate operation (1000 mA g) at high speeds. -1 It can stably store and discharge energy.

[0034] At 500mA g -1 Lower cycle detection, 500mA g -1 Under the current density test conditions, it can continue to cycle stably for 900 hours and still maintain a relatively stable overpotential (1.72V). The results are as follows: Figure 6 As shown, the discharge-charge overpotential increased from 0.5V (first cycle) to 1.8V (900th cycle), further demonstrating the excellent catalytic performance and stability of the lithium-oxygen battery based on the highly active electrocatalyst anode material from open-pit coal mine solid waste.

[0035] Subsequent investigations revealed that carbonaceous materials in coal gasification slag are prone to electrochemical oxidation during long-term high-potential cycling, which reduces the conductivity of the carbonaceous materials and increases the charge transfer resistance. Therefore, the introduction of nitrogen-containing sources (0.1 g urea and 0.05 g Co(NO3)2·6H2O) into the solvothermal reaction precursor can adjust the electronic structure of the carbonaceous components and enhance conductivity. The molybdenum oxide / cobalt oxide heterostructure can optimize the adsorption energy of oxygen species, synergistically improve ORR / OER activity, and inhibit structural reconstruction during cycling. The discharge-charge overpotential increased from 0.4V (1st cycle) to 1.5V (900th cycle).

[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. Preparation of highly active electrocatalyst material for coal gasification fine slag, characterized in that, Includes the following steps: S1. Preparation of modified coal gasification fine slag: Coal gasification fine slag and sodium carbonate are mixed and ground in a mass ratio, and calcined at 800-900 degrees Celsius for 1-4 hours to obtain calcined fine slag; The calcined fine slag is mixed with a hydrofluoric acid solution with a mass concentration of 5-15% at a solid-liquid ratio of 0.25 g / ml, stirred at room temperature for 20-28 hours, and then washed and dried to obtain modified coal gasification fine slag; S2. Preparation of highly active electrocatalyst material: The modified coal gasification fine slag, ammonium molybdate, and anhydrous glucose are dissolved in deionized water, stirred evenly, and then transferred to a high-pressure reactor. The reaction is carried out at 160-200 degrees Celsius for 10-14 hours. The reaction product is washed and dried to obtain the highly active electrocatalyst material.

2. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of the coal gasification fine slag to sodium carbonate is 3:

2.

3. The preparation method according to claim 1, characterized in that, In step S1, the calcination temperature is 875 degrees Celsius and the calcination time is 2.5 hours.

4. The preparation method according to claim 1, characterized in that, In step S2, the mass ratio of the modified coal gasification fine slag, ammonium molybdate, and anhydrous glucose is 1:2:0.

6.

5. The preparation method according to claim 1, characterized in that, In step S2, the solvothermal reaction temperature is 180 degrees Celsius and the reaction time is 12 hours.

6. A highly active electrocatalyst material for coal gasification fine slag, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

7. The application of the highly active electrocatalyst material for coal gasification fine slag as described in any one of claims 6, characterized in that, The material is used as a positive electrode electrocatalyst in lithium-air batteries.

8. The application as described in claim 6, characterized in that, The highly active electrocatalyst material is mixed with conductive carbon black and binder at a mass ratio of 7:2:1 to form a slurry, which is then coated onto a conductive current collector and dried to form the positive electrode of a lithium-air battery.

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