Preparation method of chlorine-containing carbon-based heterogeneous composite negative electrode material for sodium ion battery
By using mechanical mixing method in sodium ion batteries, hard carbon-soft carbon heterostructure composite materials are prepared, combined with chlorine-containing plastics and asphalt, the shortcomings in the stability and rate performance of the negative electrode materials of sodium ion batteries are solved, and high performance is achieved The preparation of sodium storage materials reduces production costs and is suitable for industrial production.
Patent Information
- Application Number
- CN202310152579.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-02-22
- Publication Date
- 2024-12-06
- Estimated Expiration
- 2043-02-22
AI Technical Summary
The negative electrode materials of existing sodium ion batteries have shortcomings in terms of stability and rate performance, especially the disordered structure of hard carbon leads to low electron conductivity, and the low pitch of graphite layer of soft carbon affects sodium ion embedding, resulting in sodium storage capacity. Insufficient, and most preparation methods are complex and costly, affecting industrial production.
Based on the dehalogenation reaction of chlorine-containing plastics, combined with asphalt materials, a hard carbon-soft carbon heterostructure composite was prepared, and chlorine-containing composite was ground in a strong alkali and N,N-dimethylformamide solution. Plastic and asphalt are subsequently calcined to form a hard carbon-soft carbon composite.
It achieves high reversible capacity, stable circulation performance and excellent rate performance, reduces production costs, solves environmental pollution problems, and is suitable for industrial production.
Smart Images
Figure CN116143103B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of methods for preparing carbon-based electrode materials for sodium ion batteries, and in particular relates to a method for preparing chlorine-containing carbon-based heterogeneous composite negative electrode materials for sodium ion batteries. Background Art
[0002] After decades of development, lithium-ion batteries are one of the most successful secondary ion batteries with high energy density and excellent performance. However, the geographical distribution and other limitations of lithium resources have increased their cost prices and made their application as large-scale grid-scale energy storage devices more challenging. Recently, sodium-ion batteries have been considered an ideal complement to lithium-ion batteries because they have similar physicochemical and electrochemical properties and ubiquitous sodium resources. However, graphite, as a commercial negative electrode for lithium-ion batteries, cannot provide the required Na+ storage capacity due to its unstable thermodynamic properties and insufficient ion activation. Therefore, the key to the research and development of sodium-ion batteries is to develop negative electrode materials that match them.
[0003] Among various alternative negative electrode materials, carbon materials have been extensively studied due to their wide sources, stable chemical properties, and low prices. Among them, hard carbon is composed of abundant pores, defects, and graphite crystallites, and has shown the characteristics of a potential anode material for sodium-ion batteries. By integrating the Na+ storage mechanisms of adsorption, insertion, and pore filling, it can provide highly reversible capacity and suitable working potential. However, its disordered structure easily leads to low electronic conductivity and has the defect of poor rate performance. Compared with hard carbon, soft carbon is a graphitizable carbon material with a more ordered structure, abundant graphite areas, and fewer defects, so it can produce higher electronic conductivity. However, soft carbon cannot effectively embed sodium ions due to the low interlayer spacing of graphite, which affects its sodium storage capacity. How to take the advantages of both and construct a composite carbon material that meets the requirements of sodium-ion batteries is the focus of current research. For example, CN 109980212A discloses a method for preparing a soft carbon-hard carbon composite negative electrode material for sodium ion batteries, the process of which includes using glucose as a carbon source, growing a hard carbon material on nickel foam by a hydrothermal method, then heat-treating and catalyzing graphitization to produce soft carbon, and finally etching to obtain the final product, which can be applied to the negative electrode of a sodium ion battery. CN 111293301 A reports the preparation of a soft / hard carbon composite porous material for a sodium ion battery, the process of which mainly includes first synthesizing a soft carbon carbon source metal organic framework (ZIF-67), then mixing with a hard carbon carbon source polyvinyl alcohol to form a gel, and finally carbonizing to obtain a composite carbon material, which can be used for the negative electrode of a sodium ion battery to show a high reversible capacity and good cycle stability. In addition, most methods for preparing soft carbon-hard carbon composite materials involve complex synthesis steps, expensive carbon source precursors, and low yields, which seriously affect production efficiency and production costs. Therefore, selecting low-value carbon sources, developing simple synthesis methods, and constructing high-performance hard carbon-soft carbon heterostructure negative electrode materials are of great significance for the industrial production of sodium-ion batteries. Summary of the invention
[0004] The purpose of the present invention is to provide a method for preparing a chlorine-containing carbon-based heterogeneous composite negative electrode material for a sodium ion battery. On the basis of realizing the dehalogenation reaction of chlorine-containing plastics by a simple mechanical mixing method, a hard carbon-soft carbon heterostructure composite material is successfully constructed by composite asphalt materials. The negative electrode of the sodium ion battery can exhibit high reversible capacity, stable cycle performance and excellent rate performance.
[0005] The technical solution adopted by the present invention is a method for preparing a chlorine-containing carbon-based heterogeneous composite negative electrode material for a sodium ion battery, and the specific operating steps are as follows:
[0006] Step 1, dissolving a strong base in N,N-dimethylformamide to obtain solution A;
[0007] Step 2: Add chlorine-containing plastic and asphalt to solution A in sequence, grind evenly, and obtain a mixed slurry;
[0008] Step 3: drying the mixed slurry obtained in step 2 to obtain a hard carbon-soft carbon precursor;
[0009] Step 4: calcine the hard carbon-soft carbon precursor obtained in step 3 at 600-1000° C. in an inert atmosphere, then wash to neutrality, and dry to obtain a hard carbon-soft carbon composite negative electrode material.
[0010] The present invention is also characterized in that:
[0011] The mass ratio of the strong base and the N,N-dimethylformamide component in step 1 is 1:1-30.
[0012] The strong base is any one of KOH and NaOH or a combination of the two, and the mass ratio of the two components is 1:1-5.
[0013] In step 2, the chlorine-containing plastic is polyvinyl chloride, polyvinylidene chloride or chlorinated polyvinyl chloride.
[0014] In step 2, the mass ratio of chlorine-containing plastic to asphalt is 1:1-10.
[0015] In step 4, the heating rate is 2-10°C / 111, and the calcination time is 1-5h.
[0016] In step 4, the inert atmosphere is nitrogen or argon.
[0017] The hard carbon-soft carbon heterogeneous composite negative electrode material is obtained by adopting the preparation method of the chlorine-containing carbon-based heterogeneous composite negative electrode material for sodium ion batteries of the present invention.
[0018] Hard carbon-soft carbon heterocomposites as anode materials for sodium-ion batteries.
[0019] The beneficial effects of the present invention are:
[0020] The hard carbon of the present invention uses chlorine-containing plastic as a hard carbon precursor. This type of polymer is a long-chain structure with high carbon density, which can greatly promote the cyclization of aromatic hydrocarbons and can usually be used as a high-quality precursor for manufacturing hard carbon. However, the treatment of chlorine-containing plastics is prone to many pollution problems. For example, dangerous byproducts such as Cl2, HCl and organic chlorides will be produced by incineration or landfilling to treat chlorine-containing plastics. Therefore, the present invention uses a chemical mechanical method to dehalogenate chlorine-containing plastics to avoid the occurrence of the above problems. Wherein a strong base is used as a dehalogenating agent, and N, N-dimethylformamide (DMF) is a solvent. Chlorine-containing plastics can be converted into high-quality carbonaceous materials, chloride-containing salts and water and other byproducts by simple grinding at room temperature. It is also found that the treated chlorine-containing plastics are highly reactive and can obtain nitrogen elements from the solvent DMF to form nitrogen-doped carbon materials. Further, petrochemical byproduct asphalt is introduced into the synthesis process, and its low cost price and high carbon yield can further reduce the production cost of the material. At the same time, the combination of highly disordered chlorine-containing plastic hard carbon and relatively ordered asphalt soft carbon can inhibit its graphitization to a certain extent, expand the interlayer spacing and promote the kinetics of sodium ion insertion / extraction reactions, thereby obtaining a high-performance sodium storage hard carbon-soft carbon negative electrode material. The carbon source used in the present invention is widely available and inexpensive, and it is easy to solve existing environmental problems. The preparation method used is simple and convenient, does not require large equipment and a harsh reaction environment, can be completed in room temperature air, has high completeness, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 This is a SEM image of the plastic-based hard carbon-soft carbon composite material in the sodium ion battery prepared in Example 1 of the present invention.
[0022] Figure 2 This is the rate performance curve of the plastic-based hard carbon-soft carbon composite material in the sodium ion battery prepared in Example 1 of the present invention.
[0023] Figure 3 This is the cycle performance curve of the plastic-based hard carbon-soft carbon composite material in the sodium ion battery prepared in Example 1 of the present invention.
[0024] Figure 4 This is a SEM image of the sodium ion battery negative electrode material prepared in Comparative Example 1 of the present invention.
[0025] Figure 5 This is a SEM image of the sodium ion battery negative electrode material prepared in Comparative Example 2 of the present invention. DETAILED DESCRIPTION
[0026] In order to further understand the present invention, the present invention is described below in conjunction with embodiments. These descriptions are only to further explain the features and advantages of the present invention and are not intended to limit the claims of the present invention.
[0027] Example 1
[0028] 4g KOH and 20g DMF were mixed to obtain solution A, and then 1g asphalt and 1g polyvinyl chloride were added to solution A and ground. The obtained dark brown slurry was dried at 80°C for 8h to obtain brown powder. The obtained brown powder was transferred to a tubular furnace for carbonization. The temperature was raised to 700°C at a heating rate of 5°C / 111 and kept constant for 2h in a nitrogen environment. The obtained carbonized sample was soaked in 10% HCl to remove impurities, and the sample was washed to neutrality, and dried at 80°C overnight to obtain a hard carbon-soft carbon composite material.
[0029] Figure 1 This is a SEM image of the hard carbon-soft carbon composite material obtained in Example 1. It can be seen that the composite material presents an irregular porous structure. Figure 2 The rate performance graph shows that the prepared composite material has a stable cycle curve at different current densities, where it can show an average reversible capacity of 2861Ah / g at 251A / g, and even if the current density increases to 10001A / g, it can still have a reversible capacity of 1051Ah / g. Figure 3 It can be seen that the discharge capacity of the prepared composite carbon material can be maintained at 2611 Ah / g after 100 cycles at 501 A / g.
[0030] Example 2
[0031] 4g KOH and 20g DMF were mixed to obtain solution A, and then 1g asphalt and 1.5g polyvinyl chloride were added to solution A and ground. The obtained dark brown slurry was dried at 80°C for 8h to obtain brown powder. The obtained brown powder was transferred to a tubular furnace for carbonization. The temperature was raised to 1000°C at a heating rate of 5°C / 111 and kept constant for 3h in a nitrogen environment. The obtained carbonized sample was soaked in 10% HCl to remove impurities, and the sample was washed to neutrality, and dried at 80°C overnight to obtain a hard carbon-soft carbon composite material.
[0032] Example 3
[0033] 4g KOH and 20g DMF were mixed to obtain solution A, and then 1g asphalt and 1g polyvinyl chloride were added to solution A and ground. The obtained dark brown slurry was dried at 80°C for 8h to obtain brown powder. The obtained brown powder was transferred to a tubular furnace for carbonization. The temperature was raised to 600°C at a heating rate of 10°C / 111 and kept constant for 5h in a nitrogen environment. The obtained carbonized sample was soaked in 10% HCl to remove impurities, and the sample was washed to neutrality, and dried at 80°C overnight to obtain a hard carbon-soft carbon composite material.
[0034] Example 4
[0035] 6g KOH and 30g DMF were mixed to obtain solution A, and then 1g asphalt and 2g polyvinyl chloride were added to solution A and ground. The obtained dark brown slurry was dried at 80°C for 8h to obtain brown powder. The obtained brown powder was transferred to a tubular furnace for carbonization. The temperature was raised to 700°C at a heating rate of 10°C / 111 and kept constant for 2h in a nitrogen environment. The obtained carbonized sample was soaked in 10% HCl to remove impurities, and the sample was washed to neutrality, and dried at 80°C overnight to obtain a hard carbon-soft carbon composite material.
[0036] Comparative Example 1
[0037] 1g of asphalt, 4g of KOH and 20g of DMF were mixed and ground, and the obtained dark brown slurry was dried at 80°C for 8h to obtain a brown powder. The obtained brown powder was transferred to a tube furnace for carbonization. The temperature was raised to 700°C at a heating rate of 5°C / 111 and kept constant for 2h in a nitrogen environment. The obtained carbonized sample was soaked in 10% HCl to remove impurities, and the sample was washed to neutrality, and dried at 80°C overnight to obtain a hard carbon-soft carbon composite material.
[0038] Figure 4 This is the SEM image of the carbon sample obtained in Comparative Example 1. It can be seen that the material presents a two-dimensional carbon nanosheet morphology. Soft carbon prepared only with asphalt as the carbon source usually has higher electronic conductivity, but the sodium ions cannot be effectively embedded in soft carbon due to the low interlayer spacing of graphite, thus affecting its sodium storage capacity.
[0039] Comparative Example 2
[0040] 1g of polyvinyl chloride, 4g of KOH and 20g of DMF were mixed and ground, and the obtained dark brown slurry was dried at 80°C for 8h to obtain a brown powder. The obtained brown powder was transferred to a tube furnace for carbonization. The temperature was raised to 700°C at a heating rate of 5°C / 111 and kept constant for 2h in a nitrogen environment. The obtained carbonized sample was soaked in 10% HCl to remove impurities, and the sample was washed to neutrality, and dried at 80°C overnight to obtain a hard carbon-soft carbon composite material.
[0041] like Figure 5 As shown, it is a SEM image of the carbon sample obtained in Comparative Example 2, and it can be seen that the material presents a relatively dense block. Hard carbon prepared using only polyvinyl chloride as a carbon source can provide highly reversible capacity and suitable working potential. However, its disordered structure easily leads to low electronic conductivity and poor rate performance.
[0042] It can be seen that the present invention further introduces petrochemical byproduct asphalt in the synthesis process, and its low cost price and high carbon yield can further reduce the production cost of the material. At the same time, the combination of highly disordered chlorine-containing plastic hard carbon and relatively ordered asphalt soft carbon can inhibit its graphitization to a certain extent, expand the interlayer spacing and promote the kinetics of sodium ion insertion / extraction reactions, thereby obtaining high-performance sodium storage hard carbon-soft carbon negative electrode materials. The carbon source used in the present invention is widely available and low in price, and it is easy to solve existing environmental problems. The preparation method used is simple and convenient, does not require large-scale equipment and harsh reaction environment, can be completed under room temperature and air, has high completeness, and is suitable for industrial production.
Claims
1. A method for preparing a chlorine-containing carbon-based heterogeneous composite negative electrode material for a sodium ion battery, characterized in that: The specific steps are as follows: Step 1, dissolving a strong base in N,N-dimethylformamide to obtain solution A; Step 2: adding chlorine-containing plastic and asphalt to solution A in sequence, grinding evenly, and obtaining a mixed slurry; the mass ratio of the chlorine-containing plastic to the asphalt is 1:1-10; Step 3: drying the mixed slurry obtained in step 2 to obtain a hard carbon-soft carbon precursor; Step 4: calcine the hard carbon-soft carbon precursor obtained in step 3 at 600-1000° C. in an inert atmosphere, then wash to neutrality, and dry to obtain a hard carbon-soft carbon composite negative electrode material.
2. The method for preparing a chlorine-containing carbon-based heterogeneous composite negative electrode material for a sodium ion battery according to claim 1, characterized in that: The mass ratio of the strong base and the N,N-dimethylformamide component in step 1 is 1:1-30.
3. The method for preparing a chlorine-containing carbon-based heterogeneous composite negative electrode material for a sodium ion battery according to claim 1, characterized in that: The strong base is any one of KOH and NaOH or a combination of the two, and the mass ratio of the two components is 1:1-5.
4. The method for preparing a chlorine-containing carbon-based heterogeneous composite negative electrode material for a sodium ion battery according to claim 1, characterized in that: In step 2, the chlorine-containing plastic is polyvinyl chloride, polyvinylidene chloride or chlorinated polyvinyl chloride.
5. The method for preparing a chlorine-containing carbon-based heterogeneous composite negative electrode material for a sodium ion battery according to claim 1, characterized in that: In step 4, the heating rate is 2-10°C / min, and the calcination time is 1-5h.
6. The method for preparing a chlorine-containing carbon-based heterogeneous composite negative electrode material for a sodium ion battery according to claim 1, characterized in that: In step 4, the inert atmosphere is nitrogen or argon.
7. A hard carbon-soft carbon heterogeneous composite negative electrode material obtained by the preparation method according to any one of claims 1 to 6.
8. Use of the hard carbon-soft carbon heterocomposite material according to claim 7 as a negative electrode material in a sodium ion battery.