Method for preparing hard carbon anode material for sodium-ion battery by modifying industrial waste activated carbon

Abstract

The present invention discloses a method for preparing a hard carbon anode material for sodium-ion batteries by modifying industrial waste activated carbon. Using industrial waste activated carbon as the raw material, a polymer as the modifier, and water or an organic solvent as the solvent, through a process of first mixing, then medium-low temperature pretreatment, and finally high-temperature carbonization, a hard carbon anode material for sodium-ion batteries is obtained. The method of the present invention is simple, the process is environmentally friendly, it can realize the waste utilization of waste activated carbon generated in the waste gas treatment fields of the electronics industry, the shoe-making industry or the printing industry, and the prepared hard carbon has the characteristics of high yield, good electrochemical performance and low cost.

Description

Technical Field

[0001] The invention relates to a method for preparing a hard carbon negative electrode material for a battery, in particular to a method for preparing a hard carbon negative electrode material for a sodium ion battery by modifying industrial waste activated carbon. Background Art

[0002] In recent years, batteries have played an increasingly important role in people's production and life. Compared with traditional lithium-ion batteries, sodium-ion batteries have many advantages such as richer raw material sources, lower costs, better low-temperature performance, and higher safety, which makes sodium-ion batteries have broad application prospects in energy storage and low-speed electric vehicles.

[0003] Studies have shown that among the structural materials of sodium-ion batteries, hard carbon is the negative electrode material with the most application potential for sodium-ion batteries, and using biomass as a precursor to prepare hard carbon is the most widely used method for industrial preparation of hard carbon negative electrode materials for sodium-ion batteries at this stage.

[0004] However, the raw materials for preparing hard carbon materials are mainly coconut shells produced in Southeast Asia. The distance is long and the transportation cost is too high. According to the survey results, the carbon content of biomass is about 20%. Taking into account the processing loss, the mass ratio of biomass to hard carbon output is about 6:1. In other words, the negative electrode material required for the production of 1GWh sodium-ion battery requires about 9,000 tons of coconut shells, while the total annual output of coconut shells in the world is only more than 1 million tons. In addition, coconut shells are also used as raw materials for activated carbon and other purposes. Therefore, there are fewer coconut shells that can be used for hard carbon production. Therefore, according to the current hard carbon processing technology, there are major problems with the source of raw materials, resulting in high hard carbon costs and unfavorable large-scale production.

[0005] In addition, studies have shown that the hard carbon negative electrode produced by traditional processes has problems such as low specific capacity, low first coulombic efficiency, and poor cycle performance, which limits the improvement of the overall energy density of sodium-ion batteries.

[0006] Therefore, how to reduce the dependence of hard carbon materials on coconut shells, reduce the production cost of hard carbon materials, and improve the performance of hard carbon negative electrode materials for sodium ion batteries are technical problems that technicians in this field urgently need to solve.

[0007] As an alternative, there are reports showing that hard carbon can be prepared using agricultural waste and solid waste as hard carbon sources. However, the hard carbon prepared using agricultural waste and solid waste as precursors has problems such as poor uniformity, unstable specific capacity, and high ash content, which makes it difficult to use in sodium-ion batteries.

[0008] Activated carbon is a completely different carbon material from hard carbon. As an adsorbent and for other uses, it has extensive and large-scale applications in industry. Especially in the field of waste gas treatment in the electronics industry, shoe-making industry, printing industry, etc., activated carbon is often used to adsorb and treat the organic waste gas generated during the processing. However, due to the strong adsorption ability of activated carbon and the lack of desorption ability, the used activated carbon is difficult to be recycled and reused, and is often treated as industrial waste, which brings a certain burden to enterprises and also causes waste of activated carbon resources.

[0009] Since activated carbon cannot be directly used as the anode material of sodium-ion batteries, if the industrial waste activated carbon can be used as the precursor of hard carbon materials, it will greatly reduce the dependence of hard carbon on coconut shells, thereby reducing the production cost of hard carbon, and can realize the recycling of waste activated carbon, reduce the treatment burden of related enterprises, and reduce the waste of activated carbon resources.

[0010] For example, the patent with the publication number CN117894959A discloses a preparation method of an activated carbon anode material for sodium-ion batteries, specifically discloses that activated carbon is treated with aluminum nitrate to obtain alumina-modified activated carbon, which can be used as the anode material of sodium-ion batteries.

[0011] For example, the patent with the publication number CN117208888A discloses a manufacturing process of a hard carbon anode material for sodium-ion batteries, specifically discloses that activated carbon is modified by using resorcinol formaldehyde resin to prepare a hard carbon material for sodium-ion batteries.

[0012] However, the above-mentioned existing processes all use unused activated carbon as the precursor to prepare hard carbon, and do not solve the problems of resource waste and large treatment burden of waste activated carbon. At present, there is no report showing that industrial waste activated carbon can be used as the precursor of sodium-ion battery hard carbon materials. Whether it can be used as the precursor of hard carbon materials and how to deal with it during the application process are unknown to technicians. Summary of the Invention

[0013] In order to solve the above technical problems, the present invention provides a method for preparing a hard carbon anode material for sodium-ion batteries by modifying industrial waste activated carbon. The method of the present invention is simple, the process is environmentally friendly, the waste utilization of waste activated carbon can be realized, and the prepared hard carbon has the characteristics of high yield, good electrochemical performance and low cost.

[0014] One of the technical solutions of the present invention:

[0015] Provided is a method for preparing a hard carbon anode material for a sodium-ion battery by modifying industrial waste activated carbon. The method uses industrial waste activated carbon as the raw material, a polymer as the modifier, and water or an organic solvent as the solvent. Through a process of first mixing, then pre-treating at medium and low temperatures, and finally carbonizing at high temperatures, a hard carbon anode material for a sodium-ion battery is obtained.

[0016] Preferably, the method for preparing a hard carbon anode material for a sodium-ion battery by modifying industrial waste activated carbon includes the following steps:

[0017] S1. Take industrial waste activated carbon and a polymer in reserve.

[0018] S2. Mix the industrial waste activated carbon, the polymer, and the solvent to obtain a mixture.

[0019] S3. Place the mixture from S2 in a ball mill for ball milling and mixing to obtain a ball-milled material.

[0020] S4. Dry the ball-milled material from S3 to obtain a dried material.

[0021] S5. Place the dried material from S4 in a muffle furnace and pre-treat it in an air atmosphere at 300 - 600 °C for 1 - 4 h to obtain a pre-treated material.

[0022] S6. Transfer the pre-treated material from S5 to a tubular furnace and carbonize it in an inert gas atmosphere at 1000 - 1400 °C for 0.5 - 10 h, take it out and cool it to obtain a hard carbon anode material for a sodium-ion battery.

[0023] Preferably, in the method for preparing a hard carbon anode material for a sodium-ion battery by modifying industrial waste activated carbon, the industrial waste activated carbon is the waste activated carbon generated in the field of waste gas treatment in the electronics industry, the shoe-making industry, or the printing industry.

[0024] Preferably, in the method for preparing a hard carbon anode material for a sodium-ion battery by modifying industrial waste activated carbon, the polymer is one or any combination of polyvinyl alcohol, polyethylene glycol, polypropylene, or polyethylene terephthalate.

[0025] Preferably, in the method for preparing a hard carbon anode material for a sodium-ion battery by modifying industrial waste activated carbon, the organic solvent is hexafluoroacetone.

[0026] Preferably, in the method for preparing a hard carbon anode material for a sodium-ion battery by modifying industrial waste activated carbon, the mixing mass ratio of the industrial waste activated carbon to the polymer is 1:0.1 - 30.

[0027] Preferably, in the method for preparing a hard carbon anode material for a sodium-ion battery by modifying industrial waste activated carbon, the mixing mass ratio of the total mass of the industrial waste activated carbon and the polymer to the solvent is 1:0.5 - 2.

[0028] Preferably, in the method for preparing the hard carbon negative electrode material for sodium-ion batteries by modifying the aforementioned industrial waste activated carbon, the rotation speed of the ball mill is 300-500 rpm, and the ball milling time is 1-3 h.

[0029] The second technical solution of the present invention:

[0030] Provide a hard carbon negative electrode material for sodium-ion batteries prepared according to the aforementioned method.

[0031] The third technical solution of the present invention:

[0032] Provide an application of the aforementioned hard carbon negative electrode material as a hard carbon negative electrode material for sodium-ion batteries.

[0033] Advantages of the present invention:

[0034] 1. The processing technology of the hard carbon negative electrode material of the present invention mainly includes several steps such as mixing, medium and low temperature pretreatment, and high temperature carbonization. The process is simple, convenient for industrial implementation, and can be widely promoted.

[0035] 2. The hard carbon negative electrode material of the present invention is prepared using industrial waste activated carbon as a precursor. On the one hand, it solves the problems of difficult treatment and resource waste of waste activated carbon, realizing waste utilization; on the other hand, it greatly reduces the dependence of hard carbon on coconut shells and reduces the production cost of hard carbon.

[0036] 3. When processing the hard carbon negative electrode material of the present invention, water-soluble polymers and water can be used as solvents, and better environmental protection effects can be achieved during the processing.

[0037] 4. The hard carbon precursor of the present invention is waste activated carbon, and the adsorbed substances in it can be used as a pore blocker in the present invention to block the surface pores of the activated carbon, improving the pore blocking effect. Therefore, compared with using brand-new activated carbon as a precursor, the hard carbon prepared using waste activated carbon in the present invention has better electrochemical performance.

[0038] 5. The process of the present invention first performs medium and low temperature pretreatment in an air atmosphere, enabling the adsorbed substances in the waste activated carbon to be better carbonized, effectively forming closed pores, and further improving the electrochemical performance of the hard carbon; at the same time, this process can introduce oxygen-containing functional groups at the pore blocking sites, further improving the yield and electrochemical performance of the hard carbon. Description of the drawings

[0039] Attached Figure 1 It is the charge-discharge curve graph of the hard carbon negative electrode materials of control groups 1-2 and examples 1-7. Detailed implementation manners

[0040] The following further illustrates the present invention in conjunction with embodiments, but it is not used as a basis for limiting the present invention.

[0041] The industrial waste activated carbon used in the embodiments of the present invention is the waste activated carbon generated in the fields of the electronics industry, the shoe-making industry, and the printing industry.

[0042] The activated carbon used in the embodiments of the present invention is a porous adsorbent. After being used in fields such as the electronics industry, the shoe-making industry, and the printing industry, the adsorbed substances are mainly volatile organic waste gases such as VOCs, mainly including organic waste gases such as aliphatic hydrocarbons, aromatic compounds, ketones, and esters. These substances will escape or carbonize during the pre-oxidation and high-temperature carbonization processes and become part of the hard carbon negative electrode.

[0043] Embodiments of the present invention

[0044] Embodiment 1 A method for preparing a hard carbon negative electrode material for a sodium-ion battery by modifying industrial waste activated carbon, the steps are as follows:

[0045] S1. Take 100 g of industrial waste activated carbon and 25 g of polyvinyl alcohol for standby;

[0046] S2. Mix all the industrial waste activated carbon and polyvinyl alcohol with 125 g of water to obtain a mixture;

[0047] S3. Place the mixture of S2 in a ball mill at 400 rpm and ball mill for 2 h to obtain a ball-milled material;

[0048] S4. Dry the ball-milled material of S3 to obtain a dry material;

[0049] S5. Place the dry material of S4 in a muffle furnace and pretreat it for 2 h in an air atmosphere at 400 °C to obtain a pretreated material;

[0050] S6. Transfer the pretreated material of S5 to a tubular furnace, carbonize it for 2 h in an argon atmosphere at 1400 °C, take it out and cool it to obtain a hard carbon negative electrode material for a sodium-ion battery.

[0051] Embodiment 2 A method for preparing a hard carbon negative electrode material for a sodium-ion battery by modifying industrial waste activated carbon, the steps are as follows:

[0052] S1. Take 100 g of industrial waste activated carbon and 100 g of polyvinyl alcohol for standby;

[0053] S2. Mix all the industrial waste activated carbon and polyvinyl alcohol with 200 g of water to obtain a mixture;

[0054] S3. Place the mixture of S2 in a ball mill at 400 rpm and ball mill for 2 h to obtain a ball-milled material;

[0055] S4. Dry the ball-milled material of S3 to obtain a dry material;

[0056] S5. Place the dry material obtained in S4 in a muffle furnace and pretreat it in an air atmosphere at 450 °C for 2 h to obtain a pretreated material.

[0057] S6. Transfer the pretreated material obtained in S5 to a tubular furnace, carbonize it in an argon atmosphere at 1200 °C for 5 h, take it out and cool it to obtain a hard carbon negative electrode material for sodium-ion batteries.

[0058] Example 3 A method for preparing a hard carbon negative electrode material for sodium-ion batteries by modifying industrial waste activated carbon, the steps are as follows:

[0059] S1. Take 100 g of industrial waste activated carbon and 500 g of polyvinyl alcohol for standby.

[0060] S2. Mix all the industrial waste activated carbon and polyvinyl alcohol with 600 g of water to obtain a mixture.

[0061] S3. Place the mixture obtained in S2 in a ball mill at 400 rpm and ball mill it for 2 h to obtain a ball milled material.

[0062] S4. Dry the ball milled material obtained in S3 to obtain a dry material.

[0063] S5. Place the dry material obtained in S4 in a muffle furnace and pretreat it in an air atmosphere at 500 °C for 2 h to obtain a pretreated material.

[0064] S6. Transfer the pretreated material obtained in S5 to a tubular furnace, carbonize it in an argon atmosphere at 1300 °C for 4 h, take it out and cool it to obtain a hard carbon negative electrode material for sodium-ion batteries.

[0065] Example 4 A method for preparing a hard carbon negative electrode material for sodium-ion batteries by modifying industrial waste activated carbon, the steps are as follows:

[0066] S1. Take 100 g of industrial waste activated carbon and 1000 g of polyvinyl alcohol for standby.

[0067] S2. Mix all the industrial waste activated carbon and polyvinyl alcohol with 1100 g of water to obtain a mixture.

[0068] S3. Place the mixture obtained in S2 in a ball mill at 400 rpm and ball mill it for 2 h to obtain a ball milled material.

[0069] S4. Dry the ball milled material obtained in S3 to obtain a dry material.

[0070] S5. Place the dry material obtained in S4 in a muffle furnace and pretreat it in an air atmosphere at 300 °C for 2 h to obtain a pretreated material.

[0071] S6. Transfer the pretreated material obtained in S5 to a tubular furnace, carbonize it in an argon atmosphere at 1000 °C for 5 h, take it out and cool it to obtain a hard carbon negative electrode material for sodium-ion batteries.

[0072] Example 5 A method for preparing a hard carbon anode material for sodium-ion batteries by modifying industrial waste activated carbon, the steps are as follows:

[0073] S1. Take 100 g of industrial waste activated carbon and 500 g of polyethylene terephthalate for standby;

[0074] S2. Mix all the industrial waste activated carbon, polyvinyl alcohol and 600 g of water to obtain a mixture;

[0075] S3. Place the mixture of S2 in a ball mill at 400 rpm and ball mill for 2 h to obtain a ball milled material;

[0076] S4. Dry the ball milled material of S3 to obtain a dried material;

[0077] S5. Place the dried material of S4 in a muffle furnace and pretreat it in an air atmosphere at 400 °C for 2 h to obtain a pretreated material;

[0078] S6. Transfer the pretreated material of S5 to a tube furnace, carbonize it in an argon atmosphere at 1400 °C for 5 h, take it out and cool it to obtain a hard carbon anode material for sodium-ion batteries.

[0079] Example 6 A method for preparing a hard carbon anode material for sodium-ion batteries by modifying industrial waste activated carbon, the steps are as follows:

[0080] S1. Take 100 g of industrial waste activated carbon and 10 g of polyethylene glycol for standby;

[0081] S2. Mix all the industrial waste activated carbon and polyethylene glycol with 55 g of water to obtain a mixture;

[0082] S3. Place the mixture of S2 in a ball mill at 300 rpm and ball mill for 3 h to obtain a ball milled material;

[0083] S4. Dry the ball milled material of S3 to obtain a dried material;

[0084] S5. Place the dried material of S4 in a muffle furnace and pretreat it in an air atmosphere at 300 °C for 4 h to obtain a pretreated material;

[0085] S6. Transfer the pretreated material of S5 to a tube furnace, carbonize it in a nitrogen atmosphere at 1000 °C for 10 h, take it out and cool it to obtain a hard carbon anode material for sodium-ion batteries.

[0086] Example 7 A method for preparing a hard carbon anode material for sodium-ion batteries by modifying industrial waste activated carbon, the steps are as follows:

[0087] S1. Take 100 g of industrial waste activated carbon and 3000 g of polypropylene for standby;

[0088] S2. Mix all industrial waste activated carbon and polypropylene with 6200 g of hexafluoroacetone to obtain a mixture;

[0089] S3. Place the mixture from S2 in a ball mill at 500 rpm and ball mill for 1 h to obtain a ball milled material;

[0090] S4. Dry the ball milled material from S3 to obtain a dried material;

[0091] S5. Place the dried material from S4 in a muffle furnace and pretreat for 1 h under an air atmosphere at 600 °C to obtain a pretreated material;

[0092] S6. Transfer the pretreated material from S5 to a tubular furnace and carbonize for 0.5 h under a nitrogen atmosphere at 1400 °C, take out and cool to obtain a hard carbon negative electrode material for sodium ion batteries.

[0093] Control Group 1 A method for preparing a hard carbon negative electrode material for sodium ion batteries by modifying industrial waste activated carbon. In this control group, no modifying organic matter was added, and the remaining steps remained unchanged. The preparation steps are as follows:

[0094] S1. Take 100 g of industrial waste activated carbon for standby;

[0095] S2. Mix all the industrial waste activated carbon with 600 g of water to obtain a mixture;

[0096] S3. Place the mixture from S2 in a ball mill at 400 rpm and ball mill for 2 h to obtain a ball milled material;

[0097] S4. Dry the ball milled material from S3 to obtain a dried material;

[0098] S5. Place the dried material from S4 in a muffle furnace and pretreat for 2 h under an air atmosphere at 400 °C to obtain a pretreated material;

[0099] S6. Transfer the pretreated material from S5 to a tubular furnace and carbonize for 2 h under an argon atmosphere at 1400 °C, take out and cool to obtain a hard carbon negative electrode material for sodium ion batteries.

[0100] Control Group 2 A method for preparing a hard carbon negative electrode material for sodium ion batteries by modifying industrial waste activated carbon. In Control Group 2, no pre-oxidation treatment was carried out, and the remaining steps remained unchanged. The preparation steps are as follows:

[0101] S1. Take 100 g of industrial waste activated carbon and 25 g of polyvinyl alcohol for standby;

[0102] S2. Mix all the industrial waste activated carbon, polyvinyl alcohol with 125 g of water to obtain a mixture;

[0103] S3. Place the mixture from S2 in a ball mill at 400 rpm and ball mill for 2 h to obtain a ball milled material;

[0104] S4. Dry the ball-milled abrasive in S3 to obtain dry material;

[0105] S5. Place the dry material in S4 in a tube furnace, perform carbonization treatment for 2 h in an argon atmosphere at 1400 °C, take it out and cool to obtain a hard carbon negative electrode material for sodium-ion batteries.

[0106] The charge-discharge performance of the hard carbon materials prepared in Control Groups 1-2 and Examples 1-7 is shown in the following table:

[0107] Sample Type of modified organic matter Mass ratio of activated carbon to organic matter Pre-oxidation temperature (°C) High-temperature carbonization temperature (°C) Charge specific capacity (mAh / g) Discharge specific capacity (mAh / g) Initial Coulombic efficiency (%) Control group 1 None / 400 1400 26.8 111.7 24.0 Control group 2 Polyvinyl alcohol 1:0.25 / 1400 114.3 170.4 67.1 Example 1 Polyvinyl alcohol 1:0.25 400 1400 168.1 209.2 80.3 Example 2 Polyvinyl alcohol 1:1 450 1200 191.8 230.0 83.4 Example 3 Polyvinyl alcohol 1:5 500 1300 210.4 241.3 87.2 Example 4 Polyvinyl alcohol 1:10 300 1000 207.1 249.7 82.9 Example 5 Polyethylene terephthalate 1:5 400 1400 220.7 252.4 87.4 Example 6 Polyethylene glycol 1:0.1 300 1000 136.5 150.9 90.4 Example 7 Polypropylene 1:30 600 1400 221.2 265.6 83.3

[0108] As can be seen from the above table, the charge-discharge specific capacities of the industrial waste activated carbon itself in Control Group 1 are both relatively low, and the initial Coulombic efficiency is only 24.0%. For the samples in Control Group 2 that were not pre-oxidized, their charge-discharge performance is worse than that of the samples in Example 1 that were pre-oxidized, and the initial Coulombic efficiency is also relatively low.

[0109] The charge-discharge performance of the hard carbon negative electrode materials prepared by the process of the present invention is relatively high, and the initial Coulombic efficiency is higher than 80%.

[0110] As mentioned above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a hard carbon negative electrode material for a sodium ion battery by modifying industrial waste activated carbon, characterized in that: The steps include: S1. Take industrial waste activated carbon and high molecular polymer for use; S2. mixing industrial waste activated carbon, a polymer and a solvent to obtain a mixture; S3. The mixture of S2 is placed in a ball mill and mixed to obtain a ball mill material; S4. Dry the ball mill material of S3 to obtain dry material; S5. The dried material of S4 is placed in a muffle furnace and pretreated in an air atmosphere at 300-600°C for 1-4h to obtain a pretreated material; S6. The pretreated material of S5 is transferred to a tubular furnace, carbonized under an inert gas atmosphere at 1000-1400 ° C for 0.5-10h, removed and cooled to obtain a hard carbon negative electrode material for a sodium ion battery; The high molecular polymer is one of polyvinyl alcohol, polyethylene glycol, polypropylene or polyethylene terephthalate.

2. The method for preparing a hard carbon negative electrode material for a sodium ion battery by modifying industrial waste activated carbon according to claim 1, characterized in that: The industrial waste activated carbon is waste activated carbon produced in the field of waste gas treatment in the electronics industry, shoemaking industry or printing industry.

3. The method for preparing a hard carbon negative electrode material for a sodium ion battery by modifying industrial waste activated carbon according to claim 1, characterized in that: The solvent is hexafluoroacetone.

4. The method for preparing a hard carbon negative electrode material for a sodium ion battery by modifying industrial waste activated carbon according to claim 1, characterized in that: The mixing mass ratio of the industrial waste activated carbon and the high molecular polymer is 1:0.1-30.

5. The method for preparing a hard carbon negative electrode material for a sodium ion battery by modifying industrial waste activated carbon according to claim 1, characterized in that: The mixing mass ratio of the total mass of the industrial waste activated carbon and the high molecular polymer to the solvent is 1:0.5-2.

6. The method for preparing a hard carbon negative electrode material for a sodium ion battery by modifying industrial waste activated carbon according to claim 1, characterized in that: The rotation speed of the ball mill is 300-500 rpm, and the ball milling time is 1-3 h.

7. A hard carbon negative electrode material for a sodium ion battery, characterized in that: Prepared according to the method according to any one of claims 1 to 6.

8. Application of a hard carbon negative electrode material as a hard carbon negative electrode material for a sodium ion battery, characterized in that: The hard carbon negative electrode material is prepared according to the method according to any one of claims 1-6.

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