A method for preparing negative electrode materials for ion batteries using vanadium-extracted slag from stone coal as raw materials

Abstract

The present invention discloses a method for preparing an ion battery negative electrode material using stone coal vanadium extraction slag as raw material, comprising: mixing the stone coal vanadium extraction slag with an alkaline solution in a mass ratio of 1:2 to 4, stirring, ultrasonically treating, and vacuum drying to obtain a block material; placing the block material in a tube furnace, heating to 300°C to 600°C under an inert atmosphere, and keeping the heat; after cooling, soaking the block material in pure water, heating in a water bath, stirring, and filtering; then soaking in a sulfuric acid solution, fully stirring, and washing with water until neutral to obtain a pretreated sample; placing the sample in a tube furnace, heating to 700°C to 1600°C under an inert atmosphere, and keeping the heat to obtain black carbon powder; removing the carbon powder, soaking and washing it with a hydrochloric acid solution or a nitric acid solution, then washing with water until neutral, and drying to obtain the stone coal vanadium extraction slag carbon negative electrode material. The present invention obtains an ion battery negative electrode material with excellent electrochemical performance, turning the stone coal vanadium extraction slag into valuable material and reducing costs.

Description

Technical Field

[0001] The invention belongs to the technical field of ion battery energy storage, and relates to a method for preparing an ion battery negative electrode material by taking vanadium-extracted slag from stone coal as raw material. Background Art

[0002] my country is one of the few countries in the world with anthracite coal resources. If six tons of anthracite coal are converted to one ton of standard coal, this represents 3.1 billion tons of standard coal. The smelting process of anthracite and vanadium ore produces a significant amount of slag, which is primarily processed to recover elements such as vanadium and iron. Furthermore, with the rapid expansion of the new energy sector, demand for battery anode materials continues to grow.

[0003] In 2022, global anode material shipments increased by 71.9% year-on-year to 1.556 million tons. China's anode material shipments reached 1.433 million tons, a year-on-year increase of 84.0%, a record high year-on-year growth rate. Driven by the growing demand for lithium-ion batteries, global anode material shipments are expected to reach 3.317 million tons and 8.634 million tons in 2025 and 2030, respectively, with a market size of 100 billion yuan. Therefore, there is an urgent need to develop anode material raw materials with broad availability and low cost. As one of the main energy storage components of ion batteries, suitable anode materials are a key factor in determining battery performance. Carbon materials, with their advantages in stability, safety, and affordability, have long been a hot topic in anode material research and application. However, the preparation of existing carbon materials suffers from drawbacks such as high heat treatment temperatures, high energy consumption, complex process flows, and high costs.

[0004] Chinese patent publication number CN 114365305 A discloses a lithium-ion battery negative electrode material based on spherical natural graphite containing silicate. The graphitization and carbonization temperature is above 2000°C, resulting in high energy consumption and cost, and is only applicable to lithium batteries. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a method for preparing ion battery negative electrode materials using stone coal vanadium extraction slag as raw material, thereby obtaining ion battery negative electrode materials with excellent electrochemical properties, turning stone coal vanadium extraction slag into treasure, reducing costs, and solving the problems existing in the prior art.

[0006] The technical solution adopted by the present invention is a method for preparing negative electrode materials for ion batteries using vanadium-extracted slag from stone coal as raw materials, which specifically includes the following steps:

[0007] S1: Mix the vanadium-extracted stone coal slag with 2 mol / L~6 mol / L potassium hydroxide or sodium hydroxide solution in a mass ratio of 1:(2~4), stir, ultrasonicate, mix thoroughly, and vacuum dry to obtain a blocky substance;

[0008] S2: The block material is placed in a tube furnace, sealed, and heated to 300°C~600°C under an inert atmosphere for 3h~6h. During the pre-carbonization, the potassium hydroxide or sodium hydroxide introduced in the previous step reacts more deeply with the material (i.e., stone coal vanadium extraction slag), thereby expanding the carbon layer spacing and eliminating silica impurities.

[0009] S3: After cooling, soak the block in pure water, heat it in a water bath, stir it, and filter it, repeating this process several times; then soak it in a 2mol / L~6mol / L sulfuric acid solution for 5h~10h to wash away the excess alkali introduced in the previous step, stir it thoroughly, wash it with water until it is neutral, and wash away the sulfuric acid to obtain a pretreated sample; the introduced sulfur can be removed in the subsequent high-temperature heat treatment process;

[0010] S4: Place the sample in a tube furnace, seal it, and heat it to 700°C~1600°C under an inert atmosphere. Keep it warm for 2h~5h to obtain black carbon powder. The second step is carbonization to carbonize and shape the material.

[0011] S5: Take out the carbon powder, soak and wash it in 2mol / L~6mol / L hydrochloric acid or nitric acid solution for 5h~10h to further wash away the sodium and potassium elements, then wash it with water until it is neutral and dry it in a vacuum oven to obtain the stone coal vanadium slag carbon material.

[0012] Furthermore, in S1, the alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution.

[0013] Furthermore, in S1, vacuum drying is performed at a temperature of 50° C. to 100° C. for 5 h to 12 h.

[0014] Furthermore, in S2, the heating rate is 1°C / min to 5°C / min.

[0015] Furthermore, in S3, the water bath heating temperature is 60°C to 100°C.

[0016] Furthermore, in S4, the heating rate is 1°C / min to 5°C / min.

[0017] Furthermore, in S5, after the carbon powder is soaked and washed with sulfuric acid solution, it is washed hydrothermally at 100° C. to 200° C. for 6 h to 12 h.

[0018] Furthermore, in S5, the drying process is vacuum oven drying or freeze drying.

[0019] Furthermore, in S1, the stone coal vanadium extraction slag is the waste residue after extracting vanadium ore.

[0020] The beneficial effects of the present invention are:

[0021] 1. In the embodiment of the present invention, vanadium-extracted stone coal slag is used as raw material to prepare negative electrode materials for ion batteries. Impurity removal pretreatment and heat treatment are used to pyrolyze and carbonize the stone coal slag and control its morphology. The prepared material is applied to the negative electrode of lithium / sodium / potassium ion batteries and has excellent electrochemical properties. This provides a new idea for the preparation of negative electrode materials for ion batteries and a solution to the problem of treating vanadium-extracted stone coal slag, turning waste into treasure.

[0022] 2. The embodiments of the present invention use vanadium slag extracted from stone coal as raw material, which is low-cost and easily available. In the process of preparing electrode materials, the process is simple and the process time is short. Only one step of heat treatment is required, which solves the problem of complex preparation process of existing graphite negative electrodes. It is suitable for large-scale industrial development and has considerable economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 It is the stone coal vanadium slag carbon material prepared in Example 1.

[0025] Figure 2 The stone coal vanadium slag carbon material prepared in Example 1 was assembled into a lithium ion battery at 0.2 A g -1 Cycling performance diagram at different current densities.

[0026] Figure 3 The stone coal vanadium slag carbon material prepared in Example 2 was assembled into a lithium ion battery at 0.2 A g -1 Cycling performance diagram at different current densities.

[0027] Figure 4 The stone coal vanadium slag carbon material prepared in Example 3 was assembled into a lithium ion battery at 0.2 A g -1 Cycling performance diagram at different current densities.

[0028] Figure 5 The vanadium extraction slag carbon material prepared in Example 3 was assembled into a sodium ion battery at 0.15 A g -1 Cycling performance diagram at different current densities.

[0029] Figure 6 The stone coal vanadium slag carbon material prepared in Example 3 was assembled into a potassium ion battery at 0.1 A g -1 Cycling performance diagram at different current densities.

[0030] Figure 7 The stone coal vanadium slag carbon material prepared in Example 4 was assembled into a lithium ion battery at 0.2 A g -1 Cycling performance diagram at different current densities.

[0031] Figure 8 The stone coal vanadium slag carbon material prepared in Example 5 was assembled into a lithium ion battery at 0.2 A g -1 Cycling performance diagram at different current densities.

[0032] Figure 9 This is the XRD spectrum of the stone coal vanadium slag carbon material prepared in Example 6.

[0033] Figure 10 The stone coal vanadium slag carbon material prepared in Example 6 was assembled into a lithium ion battery at 0.2 A g -1 Cycling performance diagram at different current densities.

[0034] Figure 11 The stone coal vanadium slag carbon material prepared in Example 7 was assembled into a lithium ion battery at 0.2 A g -1 Cycling performance diagram at different current densities.

[0035] Figure 12 The stone coal vanadium slag carbon material prepared in Example 8 was assembled into a lithium ion battery at 0.2 A g -1 Cycling performance diagram at different current densities.

[0036] Figure 13 The stone coal vanadium slag carbon material prepared in Example 9 was assembled into a lithium ion battery at 0.2 A g -1 Cycling performance diagram at different current densities.

[0037] Figure 14 This is the XRD spectrum of the stone coal vanadium slag carbon material prepared in Example 10.

[0038] Figure 15 The stone coal vanadium slag carbon material prepared in Example 10 was assembled into a lithium ion battery at 0.2 A g -1 Cycling performance diagram at different current densities. DETAILED DESCRIPTION

[0039] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] Example 1

[0041] A method for preparing negative electrode materials for ion batteries using vanadium-extracted slag from stone coal as raw materials, specifically comprising the following steps:

[0042] S1: After vanadium extraction from stone coal, stone coal vanadium extraction residue is obtained. The stone coal vanadium extraction residue is mixed with 2 mol / L potassium hydroxide solution at a mass ratio of 1:4, stirred, ultrasonicated for 30 minutes, and vacuum dried at 50°C for 12 hours to obtain a block material.

[0043] S2: Move the block material into a corundum ark, place it in a tube furnace, seal it, and fill it with nitrogen to expel the air in the quartz tube. Under a nitrogen atmosphere, heat it at a rate of 3°C / min and keep it at 400°C for 4 hours.

[0044] S3: After cooling, take out the ark in the quartz tube, soak the blocks in the ark in pure water, heat in a 60°C water bath, stir and filter, repeat several times, soak in 2 mol / L sulfuric acid solution for 10 h, stir thoroughly, and then wash with water to obtain the pretreated sample.

[0045] S4: The sample was moved into an ark, placed in a tube furnace, sealed, and filled with nitrogen to expel the air in the quartz tube. Under a nitrogen atmosphere, the heating rate was 3°C / min and the temperature was kept at 700°C for 5 h to obtain black carbon powder.

[0046] S5: Take out the carbon powder, soak it in 2 mol / L hydrochloric acid solution for 10 hours, then wash it with water until it is neutral and dry it in a vacuum oven to obtain the stone coal vanadium slag carbon material, such as Figure 1 shown.

[0047] S6: Assemble lithium / sodium / potassium ion batteries.

[0048] like Figure 2 As shown, a lower processing temperature is beneficial to maintaining the defect structure and forming more storage sites.

[0049] Example 2

[0050] S1: Mix vanadium-extracted stone coal slag with 6 mol / L potassium hydroxide solution in a mass ratio of 1:2, stir, ultrasonicate for 30 minutes, and vacuum dry at 100°C for 5 hours to obtain a blocky substance;

[0051] S2: The bulk material was transferred into a corundum ark, placed in a tube furnace, sealed, and filled with nitrogen to expel the air in the quartz tube. Under nitrogen atmosphere, the heating rate was 3°C / min and the temperature was kept at 400°C for 4 h.

[0052] S3: After cooling, take out the ark in the quartz tube, soak the blocks in the ark in pure water, heat in a water bath at 100°C, stir and filter, repeat several times, soak in 6 mol / L sulfuric acid solution for 5 hours, stir thoroughly, and then wash with water to obtain the pretreated sample.

[0053] S4: The sample was transferred into an ark, placed in a tube furnace, sealed, and filled with nitrogen to expel the air in the quartz tube. Under a nitrogen atmosphere, the heating rate was 5°C / min and the temperature was kept at 1000°C for 2 h to obtain black carbon powder.

[0054] S5: Take out the carbon powder, soak and wash it with 6 mol / L hydrochloric acid solution for 5 hours, then wash it with water until it is neutral, and then dry it in a vacuum oven to obtain the stone coal vanadium slag carbon material.

[0055] S6: Assemble lithium / sodium / potassium ion batteries.

[0056] like Figure 3 As shown in Figure 3, higher treatment temperature can improve the order of graphite crystallites and enhance conductivity.

[0057] Example 3

[0058] S1: Mix stone coal vanadium extraction residue with 5 mol / L potassium hydroxide solution in a mass ratio of 1:3, stir, ultrasonicate for 30 minutes, and vacuum dry at 80°C for 10 hours to obtain a block material;

[0059] S2: The bulk material was transferred into a corundum ark, placed in a tube furnace, sealed, and filled with nitrogen to expel the air in the quartz tube. Under nitrogen atmosphere, the heating rate was 3°C / min and the temperature was kept at 400°C for 4 h.

[0060] S3: After cooling, take out the ark in the quartz tube, soak the blocks in the ark in pure water, heat in a water bath at 80°C, stir and filter, repeat several times, soak in 5 mol / L sulfuric acid solution for 8 hours, stir thoroughly, and then wash with water to obtain a pretreated sample.

[0061] S4: The sample was transferred into an ark, placed in a tube furnace, sealed, and filled with nitrogen to expel the air in the quartz tube. Under a nitrogen atmosphere, the heating rate was 3°C / min and the temperature was kept at 800°C for 3 h to obtain black carbon powder.

[0062] S5: Take out the carbon powder, soak and wash it in 5 mol / L hydrochloric acid solution for 8 hours, then wash it with water until it is neutral, and then dry it in a vacuum oven to obtain the stone coal vanadium slag carbon material.

[0063] S6: Assemble lithium / sodium / potassium ion batteries.

[0064] like Figure 4-6As shown, compared with samples treated at higher temperatures, a certain defect structure is retained at this temperature, and compared with samples treated at low temperatures, the irreversible capacity sites are reduced, making it the optimal product considering the comprehensive factors of interlayer spacing and defect degree.

[0065] Example 4

[0066] Except that the mass ratio of sodium hydroxide to step S1 is changed to 1:4, the rest is the same as in Example 3. The potassium hydroxide in Example 3 is replaced by sodium hydroxide. The atomic radius scales of sodium atoms and potassium atoms are different. Potassium is relatively larger, and has a stronger effect on expanding the distance between graphite layers. Increasing the amount of sodium hydroxide and using more sodium hydroxide to compound with stone coal slag can more fully contact with silicon dioxide in stone coal slag, thereby improving the reaction efficiency, thereby improving the sample purity, and increasing the capacity. Figure 7 shown.

[0067] Example 5

[0068] Except that the heating rate in step S4 is 1°C / min, the rest are the same as in Example 3. The faster the heating rate, the faster the gas overflow speed, thereby forming large regional defects. Reducing the heating rate can make the number of defect sites larger and the distribution more uniform. Figure 8 As shown, a slower heating rate helps the material microstructure gradient to be finalized, forming a more stable structure and improving battery stability.

[0069] Example 6

[0070] Except that the holding temperature in step S4 is changed to 1200°C, the rest is the same as in Example 3. At the carbonization temperature of 1200°C, the sulfur element introduced by the pre-sulfuric acid treatment is removed at high temperature, which reduces the functional groups in the carbon material and improves the initial coulombic efficiency. At the same time, the relatively low temperature reduces energy consumption, the carbon layer spacing is relatively larger, and the capacity is higher. Figure 9-10 .

[0071] Example 7

[0072] Except that the holding temperature in step S4 is changed to 1600°C, the rest is the same as in Example 3. The higher heat treatment temperature can not only remove the foreign elements, but also facilitate the closure of defects between carbon materials, forming larger nanoscale closed pores and improving the capacity of carbon materials. Figure 11 .

[0073] Example 8

[0074] Except for taking out the carbon powder in step S5, washing it with 5 mol / L sulfuric acid, and then washing it with a hydrothermal method at 100°C to 200°C (200°C in this embodiment) for 6h to 12h (12h in this embodiment), the rest is the same as Example 3. Sulfuric acid can wash away the residual alkali in the carbon material, but it will introduce certain sulfur-related groups, which can be better removed by hydrothermal treatment (using water as the hydrothermal reaction solution). At the same time, the solvothermal method can control the formation of the phase, the size of the particle size, and the morphology. Moreover, the product has better dispersibility, thereby having a higher capacity. Figure 12 .

[0075] Example 9

[0076] Except that the holding temperature in step S2 is changed to 600°C, the rest is the same as in Example 3. At 600°C, not only silicon dioxide is removed, but also potassium enters the carbon interlayer under the thermal effect, which is beneficial to increase the carbon interlayer spacing and further improve the battery capacity. Figure 13 .

[0077] Example 10

[0078] Except that the vacuum oven drying in step S5 is replaced by freeze drying, the rest is the same as Example 3. Vacuum drying is prone to produce boiling phenomenon, which destroys the uniform temperature of the material. Freeze drying can maintain the original structure without concentration phenomenon. The better structural stability can make the battery stability of the material stronger. Figure 14-15 .

[0079] The present invention uses in-depth, multi-faceted research and analysis of the composition and structure of the vanadium-extracted stone coal slag waste material. It also incorporates the physicochemical properties of the vanadium-extracted stone coal slag waste material to address the issue of varicose changes in the microscopic layers of the vanadium-extracted stone coal slag at different temperatures. It also investigates the interaction between various additives (acids and bases) and the vanadium-extracted stone coal slag waste material. The present invention uses the vanadium-extracted stone coal slag waste material as raw material. This is the vanadium-free slag material after vanadium extraction. This material is low-cost and readily available. The electrode material preparation process is simple and time-efficient, addressing the complexities of existing graphite anode preparation processes and making it suitable for large-scale industrial development.

[0080] The stone coal vanadium slag in the embodiment of the present invention is the waste residue after the extraction of vanadium ore. Its conversion into a carbon negative electrode material requires in-depth experiments on its microstructure, and then adjusts the carbon layer spacing, stacking method, pore structure, specific surface area, distribution uniformity, etc. The embodiment of the present invention multi-dimensionally controls variables in terms of processing temperature, heating rate, acid and alkali reagents, and obtains stone coal-derived carbon with large structural layer spacing and high disorder; at a carbonization temperature of 700°C to 1600°C, the micromorphology is regulated with the aid of auxiliary agents, and the obtained carbon material is also suitable for lithium / sodium / potassium ion batteries, has low energy consumption, and is a waste-to-treasure conversion.

[0081] Comparative Example 1

[0082] Except that the mass ratio in S1 was changed to 1:1 and only stirring was performed without ultrasonication, the rest was the same as in Example 1.

[0083] Insufficient potassium hydroxide and insufficient compounding make it impossible for potassium to be evenly embedded in the carbon layers, and at the same time, silicon dioxide cannot be effectively removed, resulting in a decrease in capacity.

[0084] Comparative Example 2

[0085] Except that the heat treatment temperature in S2 is changed to 200° C., the rest is the same as in Example 1.

[0086] The lower processing temperature prevents potassium hydroxide from being fully embedded in the carbon materials, and it only contacts the surface of the carbon materials, resulting in a decrease in capacity.

[0087] Comparative Example 3

[0088] Except that sulfuric acid is replaced with hydrochloric acid in S3, the rest is the same as in Example 1.

[0089] Hydrochloric acid cannot fully wash away the alkali-related elements introduced in the previous step, resulting in alkaline substances remaining at high temperatures. On the one hand, these alkaline washing substances will damage the Ark container at high temperatures, causing the elements in the container to recombine with the material itself, resulting in a decrease in the material capacity. On the other hand, at high temperatures, the alkaline washing substances will combine and aggregate with the material more, resulting in an excessively large pore structure and interlayer spacing, which will reduce the overall capacity of the material.

[0090] Comparative Example 4

[0091] Except that the second-step carbonization temperature in S4 is 600° C., the rest is the same as in Example 1.

[0092] Too low a final carbonization temperature results in low purity, poor conductivity and low capacity of the carbon material.

[0093] Comparative Example 5

[0094] Except that sulfuric acid is used for washing in S5, the rest are the same as those in Example 1.

[0095] The use of sulfuric acid washing further introduces sulfur into the material. The incorporation of heterogeneous elements and their mixing on the surface of the material causes more irreversible sites to form on the surface, increasing the irreversible capacity of the material.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A method for preparing negative electrode materials for ion batteries using vanadium-extracted slag from stone coal as raw materials, characterized in that: The following steps are involved: S1: Mixing stone coal vanadium extraction slag with 2 mol / L~6 mol / L alkaline solution in a mass ratio of 1:2~4, stirring, ultrasonicating, and vacuum drying to obtain a block material; S2: Place the block material into a tube furnace, seal it, heat it to 300°C~600°C under an inert atmosphere, and keep it warm for 3h~6h; S3: After cooling, soak the block in pure water, heat it in a water bath, stir it, and filter it, repeating this process several times; then soak it in a 2 mol / L to 6 mol / L sulfuric acid solution for 5 h to 10 h, stir it thoroughly, and wash it with water until it is neutral to obtain a pretreated sample; S4: Place the sample in a tube furnace, seal it, and heat it to 700°C~1600°C under an inert atmosphere. Keep the temperature for 2h~5h to obtain black carbon powder. S5: Take out the carbon powder, soak and wash it with a 2mol / L~6mol / L hydrochloric acid solution or a nitric acid solution for 5h~10h, or soak and wash the carbon powder with a sulfuric acid solution, then wash it with a hydrothermal method at 100℃~200℃ for 6h~12h, then wash it with water until it is neutral, and dry it to obtain the stone coal vanadium slag carbon negative electrode material; In S3, the water bath heating temperature is 60°C to 100°C; In the above-mentioned S1, the alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution.

2. The method for preparing negative electrode materials for ion batteries using vanadium-extracted slag from stone coal as raw materials according to claim 1, characterized in that: In the S1, vacuum drying is performed at a temperature of 50° C. to 100° C. for 5 h to 12 h.

3. The method for preparing negative electrode materials for ion batteries using vanadium-extracted slag from stone coal as raw materials according to claim 1, characterized in that: In the step S2, the heating rate is 1°C / min to 5°C / min.

4. The method for preparing negative electrode materials for ion batteries using vanadium-extracted slag from stone coal as raw materials according to claim 1, characterized in that: In the step S4, the heating rate is 1°C / min to 5°C / min.

5. The method for preparing negative electrode materials for ion batteries using vanadium-extracted slag from stone coal as raw materials according to claim 1, characterized in that: In S5, the drying process is vacuum oven drying or freeze drying.

6. The method for preparing negative electrode materials for ion batteries using vanadium-extracted slag from stone coal as raw materials according to claim 1, characterized in that: In S1, the stone coal vanadium extraction slag is the waste residue after extracting vanadium ore.

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