Dual-interference chemical preparation method of high-reversible-capacity and high-platform-occupancy hard carbon negative electrode material, product and application thereof

Abstract

The present application relates to a double interference chemical preparation method of high-reversible-capacity and high-platform-occupancy hard carbon negative electrode material, and a product and application thereof, and belongs to the technical field of preparation of sodium ion battery materials.The present application provides a preparation method of high-reversible-capacity and high-platform-occupancy hard carbon negative electrode material, which takes biomass carbon source as a raw material and takes double interference chemistry (crosslinking and pore making) of organic acid salt as a reaction mechanism.The hard carbon negative electrode material of the present application is simple to prepare, strong in operability, and low in cost, and has obvious improvement effect compared with existing hard carbon materials, and the reversible capacity can be as high as 415 mAh / g at 0.1C, the sodium storage capacity is excellent, the potential commercial value is huge, and the present application is suitable for popularization and application.

Description

Technical Field

[0001] This invention relates to a dual-interference chemical preparation method for high reversible capacity and high plateau ratio hard carbon anode materials, as well as their products and applications, belonging to the field of sodium-ion battery material preparation technology. Background Technology

[0002] Sodium-ion batteries are considered a potential alternative to lithium-ion batteries due to the widespread distribution and abundant reserves of sodium. Currently, hard carbon materials are the most promising anode materials for sodium-ion batteries for rapid industrialization. This is because hard carbon materials have widely available raw materials, simple synthesis methods, relatively low cost, high sodium storage capacity, and low operating voltage.

[0003] However, hard carbon materials differ from graphite in lithium-ion batteries. Their sodium intercalation process occurs in two stages: first, a high-voltage ramp segment where sodium ions adsorb at defects and carbon layer edges; then, a low-voltage plateau segment where sodium ions intercalate between hard carbon layers and fill pores. Ideally, commercially viable hard carbon materials should possess both high reversible specific capacity and maximize the proportion of plateau capacity.

[0004] Therefore, it is necessary to study new preparation methods in order to prepare hard carbon anode materials with high reversible capacity and high plateau ratio. Summary of the Invention

[0005] In view of this, one objective of the present invention is to provide a dual-interference chemical preparation method for hard carbon anode materials with high reversible capacity and high plateau ratio; a second objective of the present invention is to provide hard carbon anode materials with high reversible capacity and high plateau ratio; and a third objective of the present invention is to provide the application of the dual-interference chemical preparation method for hard carbon anode materials with high reversible capacity and high plateau ratio in sodium-ion batteries.

[0006] To achieve the purpose of the appeal, the present invention provides the following technical solution:

[0007] 1. A dual-interference chemical preparation method for a hard carbon anode material with high reversible capacity and high plateau ratio, the dual-interference chemical preparation method comprising the following steps:

[0008] (1) Ball milling: The precursor material formed by mixing biomass carbon source and organic acid salt is placed in a ball mill and ball milled;

[0009] (2) Drying: Dry the material obtained after ball milling in step (1);

[0010] (3) Carbonization: The material dried in step (2) is carbonized at high temperature and then cooled to room temperature;

[0011] (4) Sorting: Pass the material cooled in step (3) through a vibrating screen and sorting equipment to obtain hard carbon anode material with high reversible capacity and high platform ratio.

[0012] Preferably, the biomass carbon source includes any one or more of lignin, cellulose, glucose, sucrose, starch, cotton, coconut shell, or straw;

[0013] The organic acid salts include any one or more of zinc gluconate, zinc citrate, copper citrate, magnesium gluconate, zinc acetate, sodium gluconate, calcium gluconate, sodium alginate, or potassium oxalate.

[0014] Preferably, the mass ratio of biomass carbon source to organic acid salt in the precursor material is 1:2 to 1:10.

[0015] Preferably, in step (1), the ball milling uses a planetary ball mill, the ball milling speed is 100-500 r / min, the ball milling time is 0.1-48 h, the ball milling solvent is ethanol, deionized water or no ball milling solvent, and the ball milling atmosphere is air, argon or nitrogen.

[0016] Preferably, a vacuum drying oven is used for drying in step (2), wherein the drying temperature is 50-150°C and the drying time is 2-24 hours.

[0017] Preferably, in step (3), argon, nitrogen, ammonia or hydrogen is used as the carbonization atmosphere during the high-temperature carbonization process, the high-temperature carbonization temperature is 800 to 1700°C, the heating rate during the high-temperature carbonization process is 0.5 to 10°C / min, and the holding time after heating to the target temperature is 0.5 to 5h.

[0018] Preferably, the screen of the vibrating screen is 100 to 500 mesh.

[0019] 2. Hard carbon anode materials with high reversible capacity and high plateau ratio prepared by the above dual-interference chemical preparation method.

[0020] 3. Applications of the aforementioned high reversible capacity and high plateau ratio hard carbon anode materials in sodium-ion batteries.

[0021] The beneficial effects of this invention are as follows: This invention discloses a dual-interference chemical preparation method for hard carbon anode materials with high reversible capacity and high plateau ratio. The preparation method involves treating a precursor material formed by mixing biomass carbon source and organic acid salts through ball milling, drying, high-temperature carbonization, cooling, and passing through a vibrating sieve to obtain a precursor material formed by mixing biomass carbon source and organic acid salts. This preparation method has the advantages of low cost, high carbon yield, simple material preparation, strong operability, simple reaction process, high consistency of product morphology, high safety, and high reaction efficiency. It can be seen that this invention can achieve the following effects through simple dual-interference chemistry: (1) The chemical cross-linking reaction between biomass carbon source and organic acid salts prepares hard carbon materials with high cross-linking degree and high disorder, thereby improving the overall reversible specific capacity; (2) Furthermore, the interaction between biomass and organic acid salts can generate more sub-nanometer-level closed pores or open pores with extremely small opening size inside the material, which is beneficial to increasing the sodium storage capacity of the material at low potential plateau and obtaining a hard carbon material with high plateau capacity. A high-reversible-capacity, high-plateau-ratio hard carbon anode material was obtained through a series of steps including ball milling, drying, carbonization, and sorting of biomass carbon source and organic acid salts. This invention offers a simple, highly operable, and low-cost preparation method with significant results. The high-reversible-capacity, high-plateau-ratio hard carbon anode material prepared by this invention exhibits a reversible capacity as high as 415 mAh / g at 0.1C, excellent sodium storage capacity, and significant potential commercial value, making it suitable for widespread application.

[0022] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiments of the present invention are given in detail below with reference to the accompanying drawings. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 The first charge-discharge curve of the hard carbon anode material (Al) prepared in Example 1 at 0.1C is shown.

[0025] Figure 2 The first charge-discharge curve of the hard carbon anode material (A7) prepared in Comparative Example 1 at 0.1C is shown.

[0026] Figure 3The first charge-discharge curve of the hard carbon anode material (A8) prepared in Comparative Example 2 at 0.1C is shown.

[0027] Figure 4 The image shows the XRD pattern of the hard carbon anode material (Al) prepared in Example 1.

[0028] Figure 5 The image shows the XRD pattern of the hard carbon anode material (A7) prepared in Comparative Example 1.

[0029] Figure 6 The image shows the XRD pattern of the hard carbon anode material (A8) prepared in Comparative Example 2.

[0030] Figure 7 SEM image of the hard carbon anode material (Al) prepared in Example 1;

[0031] Figure 8 SEM image of the hard carbon anode material (A7) prepared in Comparative Example 1;

[0032] Figure 9 The image shows a SEM image of the hard carbon anode material (A8) prepared in Comparative Example 2. Detailed Implementation

[0033] The present invention will be further described below with reference to embodiments, but the description of the embodiments does not limit the scope of protection of the present invention in any way. 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 in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. Unless otherwise specified, the substances or instruments used in the following embodiments can be obtained from conventional commercial channels.

[0034] Example 1:

[0035] A dual-interference chemical preparation method for a hard carbon anode material with high reversible capacity and high plateau ratio, specifically including the following steps:

[0036] (1) Ball milling: Starch and zinc gluconate were mixed in a mass ratio of 1:5 to form a precursor material and then placed in a ball mill. The mixture was ball milled at a speed of 100 r / min for 24 h. The ball milling solvent used in this process was secondary water ball and the grinding atmosphere was air.

[0037] (2) Drying: Place the material obtained by ball milling in step (1) in an oven at 100°C and dry for 12 hours;

[0038] (3) Carbonization: After grinding the material dried in step (2), place it in a high-temperature tube furnace for high-temperature carbonization. During the high-temperature carbonization process, argon is used as the carbonization atmosphere. The temperature of the high-temperature tube furnace is set as follows: when the room temperature ≤ furnace temperature < 1400℃, the temperature is increased at a rate of 0.5℃ / min. When the furnace temperature ≥ 1400℃, the temperature is held for 3 hours and then the hard carbon is allowed to cool naturally to room temperature.

[0039] (4) Sorting: The material obtained after carbonization in step (3) is passed through a 200-mesh vibrating screen and sorting equipment to obtain a hard carbon anode material (A1) with uniform particle size, high reversible capacity and high plateau ratio.

[0040] Example 2

[0041] A dual-interference chemical preparation method for a hard carbon anode material with high reversible capacity and high plateau ratio, specifically including the following steps:

[0042] (1) Ball milling: Glucose and zinc citrate were mixed in a mass ratio of 1:2 to form a precursor material and then placed in a ball mill. The mixture was ball milled at a speed of 300 r / min for 5 h. The solvent in the ball milling process was ethanol and the ball milling atmosphere was argon.

[0043] (2) Drying: Place the material obtained by ball milling in step (1) in an oven at 60°C and dry for 6 hours;

[0044] (3) Carbonization: After grinding the material dried in step (2), place it in a high-temperature tube furnace for high-temperature carbonization. During the high-temperature carbonization process, nitrogen is used as the carbonization atmosphere. The temperature of the high-temperature tube furnace is set as follows: when the room temperature ≤ furnace temperature < 1100℃, the temperature is increased at a rate of 2℃ / min. When the furnace temperature ≥ 1100℃, the temperature is maintained for 4 hours, and then the hard carbon is allowed to cool naturally to room temperature.

[0045] (4) Sorting: Pass the material obtained after carbonization in step (3) through a 300-mesh vibrating screen and sorting equipment to obtain a hard carbon anode material (A2) with uniform particle size, high reversible capacity and high plateau ratio.

[0046] Example 3

[0047] A dual-interference chemical preparation method for a hard carbon anode material with high reversible capacity and high plateau ratio, specifically including the following steps:

[0048] (1) Ball milling: lignin, cellulose and zinc acetate were placed in a ball mill in a mass ratio of 1:1:8 to form a precursor material. The material was then ball milled at a speed of 500 r / min for 12 h. Dry ball milling was used in this process, with no ball milling solvent and the ball milling atmosphere was nitrogen.

[0049] (2) Drying: Place the material obtained by ball milling in step (1) in an oven at 80°C and dry for 8 hours;

[0050] (3) Carbonization: After grinding the material dried in step (2), place it in a high-temperature tube furnace for high-temperature carbonization. During the carbonization process, ammonia is used as the carbonization atmosphere. The temperature of the high-temperature tube furnace is set as follows: when the room temperature ≤ furnace temperature < 1600℃, the temperature is increased at a rate of 4℃ / min. When the furnace temperature ≥ 1600℃, the temperature is held for 1 hour, and then the hard carbon is allowed to cool naturally to room temperature.

[0051] (4) Sorting: Pass the material obtained after carbonization in step (3) through a 100-mesh vibrating screen and sorting equipment to obtain a hard carbon anode material (A3) with uniform particle size, high reversible capacity and high plateau ratio.

[0052] Example 4

[0053] A dual-interference chemical preparation method for a hard carbon anode material with high reversible capacity and high plateau ratio, specifically including the following steps:

[0054] (1) Ball milling: Cotton and copper citrate were mixed at a mass ratio of 1:10 to form a precursor material and then placed in a ball mill. The mixture was ball milled at a speed of 400 r / min for 0.1 h. The ball milling was a dry ball milling with no ball milling solvent and argon atmosphere.

[0055] (2) Drying: Place the material obtained by ball milling in step (1) in an oven at 50°C and dry for 2 hours;

[0056] (3) Carbonization: The material dried in step (2) is ground and then placed in a high-temperature tube furnace for high-temperature carbonization. During the high-temperature carbonization process, hydrogen is used as the carbonization atmosphere. The temperature of the high-temperature tube furnace is set as follows: when the room temperature ≤ furnace temperature < 800℃, the temperature is increased at a rate of 10℃ / min. When the furnace temperature ≥ 800℃, the temperature is held for 5 hours and then the hard carbon is allowed to cool naturally to room temperature.

[0057] (4) Sorting: The material obtained after carbonization in step (3) is passed through a 400-mesh vibrating screen and sorting equipment to obtain a hard carbon anode material (A4) with uniform particle size, high reversible capacity and high plateau ratio.

[0058] Example 5

[0059] A dual-interference chemical preparation method for a hard carbon anode material with high reversible capacity and high plateau ratio, specifically including the following steps:

[0060] (1) Ball milling: Cellulose and magnesium gluconate were mixed in a mass ratio of 1:7 to form a precursor material and then placed in a ball mill. The mixture was ball milled at a speed of 500 r / min for 3 hours. The ball milling solvent was ethanol and the ball milling atmosphere was air.

[0061] (2) Drying: Place the material obtained by ball milling in step (1) in an oven at 60°C and dry for 12 hours;

[0062] (3) Carbonization: After grinding the material dried in step (2), it is placed in a high-temperature tube furnace for high-temperature carbonization. During the high-temperature carbonization process, argon is used as the high-temperature atmosphere. The temperature of the high-temperature tube furnace is set as follows: when the room temperature ≤ furnace temperature < 1700℃, the temperature is increased at a rate of 1℃ / min. When the furnace temperature ≥ 1700℃, the temperature is held for 0.5h, and then the hard carbon is allowed to cool naturally to room temperature.

[0063] (4) Sorting: The material obtained after carbonization in step (3) is passed through a 500-mesh vibrating screen and sorting equipment to obtain a hard carbon anode material (A5) with uniform particle size, high reversible capacity and high plateau ratio.

[0064] Example 6

[0065] A dual-interference chemical preparation method for a hard carbon anode material with high reversible capacity and high plateau ratio, specifically including the following steps:

[0066] (1) Ball milling: Starch, sodium gluconate and calcium gluconate are mixed in a mass ratio of 1:3:8 to form a precursor material and then placed in a ball mill. The ball milling is carried out at a speed of 100 r / min for 10 h. The ball milling solvent is secondary water and the ball milling atmosphere is nitrogen.

[0067] (2) Drying: Place the material obtained by ball milling in step (1) in an oven at 150°C and dry for 24 hours;

[0068] (3) Carbonization: The material dried in step (2) is ground and placed in a high-temperature tube furnace for high-temperature carbonization. During the high-temperature carbonization process, nitrogen is used as the carbonization atmosphere. The temperature of the high-temperature tube furnace is set as follows: when the room temperature ≤ furnace temperature < 1500℃, the temperature is increased at a rate of 5℃ / min. When the furnace temperature ≥ 1500℃, the temperature is held for 5 hours and then the hard carbon is allowed to cool naturally to room temperature.

[0069] (5) Sorting: Pass the material obtained after carbonization in step (3) through a 200-mesh vibrating screen and sorting equipment to obtain a hard carbon anode material (A6) with uniform particle size, high reversible capacity and high plateau ratio.

[0070] Comparative Example 1

[0071] A method for preparing a hard carbon anode material specifically includes the following steps:

[0072] (1) Ball milling: Place sucrose in a ball mill and dry ball mill at a speed of 300 r / min (without ball milling solvent) for 5 h. The atmosphere during the ball milling process is air.

[0073] (2) Drying: Place the material obtained by ball milling in step (1) in an oven at 60°C and dry for 12 hours;

[0074] (3) Carbonization: The material dried in step (2) is ground and then placed in a high-temperature tube furnace for high-temperature carbonization. During the high-temperature carbonization process, nitrogen is used as the carbonization atmosphere. The temperature of the high-temperature tube furnace is set as follows: when the room temperature ≤ furnace temperature < 1300℃, the temperature is increased at a rate of 5℃ / min. When the furnace temperature ≥ 1300℃, the temperature is held for 3 hours and then the hard carbon is allowed to cool naturally to room temperature.

[0075] (4) Sorting: Pass the material obtained after carbonization in step (3) through a 300-mesh vibrating screen and sorting equipment to obtain hard carbon anode material (A7) with uniform particle size.

[0076] Comparative Example 2:

[0077] A method for preparing a hard carbon anode material specifically includes the following steps:

[0078] (1) Ball milling: Zinc gluconate was placed in a ball mill and dry-milled at a speed of 300 r / min for 5 h (without ball milling solvent). The ball milling atmosphere during this process was air.

[0079] (2) Drying: Place the material obtained by ball milling in step (1) in an oven at 60°C and dry for 12 hours;

[0080] (3) Carbonization: The material dried in step (2) is ground and placed in a high-temperature tube furnace for high-temperature carbonization. During the high-temperature carbonization process, nitrogen is used as the carbonization atmosphere. The temperature of the high-temperature tube furnace is set as follows: when the room temperature ≤ furnace temperature < 1500℃, the temperature is increased at a rate of 5℃ / min. When the furnace temperature ≥ 1500℃, the temperature is held for 3 hours and then the hard carbon is allowed to cool naturally to room temperature.

[0081] (4) Sorting: The material obtained after carbonization in step (3) is passed through a 300-mesh vibrating screen and sorting equipment to obtain hard carbon anode material (A8) with uniform particle size.

[0082] Performance testing

[0083] The hard carbon anode materials A1 to A8 prepared in Examples 1 to 6 and Comparative Examples 1 to 2 were used as the positive electrode of sodium-ion batteries, metallic sodium as the negative electrode, glass fiber as the separator, and dimethyl ether (DME) solution of NaPF6 (with a concentration of 1M) as the electrolyte. The following electrochemical performance tests were performed.

[0084] The hard carbon anode materials A1 to A8 prepared in Examples 1-6 and Comparative Examples 1-2 were subjected to interlayer spacing d. 002The test analysis of charge-discharge capacity and morphology at 0.1C is shown in Table 1 below.

[0085] Table 1. Interlayer spacing and discharge capacity of hard carbon anode materials prepared by different methods.

[0086] Material <![CDATA[d 002 / nm]]> Discharge specific capacity / mAh / g Charging specific capacity / mAh / g First Coulomb Efficiency / % Platform share / % Example 1 0.419 576 415 72 75 Example 2 0.419 474 384 81 73 Example 3 0.417 429 364 85 72 Example 4 0.419 582 423 72 71 Example 5 0.416 455 367 79 66 Example 6 0.419 437 378 86 62 Comparative Example 1 0.418 241 140 58 27 Comparative Example 2 0.420 144 76 53 29

[0087] Figure 1 , Figure 2 and Figure 3 The first charge-discharge curves of the hard carbon anode materials prepared in Example 1, Comparative Example 1, and Comparative Example 2 at 0.1C are shown below. Figures 1-3 The comparison shows that the hard carbon anode material prepared by the method in Example 1 of this invention achieves a discharge capacity of 576 mAh / g, a reversible capacity of 415 mAh / g, and a coulombic efficiency of 72% during the first charge-discharge process. In contrast, the hard carbon anode material prepared by the method in Comparative Example 1 achieves a discharge capacity of 241 mAh / g, a reversible capacity of 140 mAh / g, and a coulombic efficiency of 58% during the first charge-discharge process. Furthermore, the hard carbon anode material prepared by the method in Comparative Example 2 achieves a discharge capacity of 144 mAh / g, a reversible capacity of 76 mAh / g, and a coulombic efficiency of 53% during the first charge-discharge process. Similarly, the hard carbon anode materials prepared by the methods in Examples 2 to 6 were subjected to the same first charge-discharge process, and their discharge capacity, reversible capacity, and coulombic efficiency are shown in Table 1. This demonstrates that the hard carbon anode material prepared by the method of this invention exhibits significant improvements in discharge capacity, reversible capacity, and coulombic efficiency, indicating that the modification method provided by this invention can effectively improve the sodium storage performance of hard carbon.

[0088] Figure 4 , Figure 5 and Figure 6 The images show the XRD patterns of the hard carbon anode materials prepared in Example 1, Comparative Example 1, and Comparative Example 2, respectively. Figures 4-6 The comparison shows that the hard carbon anode material prepared by the method in Example 1 of this invention exhibits a typical bimodal structure of amorphous carbon, corresponding to the (002) and (100) crystal planes respectively. After calculation, its d... 002 =0.419, while the d of the hard carbon anode materials prepared by the methods in Comparative Example 1 and Comparative Example 2 is... 002 The values ​​were 0.418 and 0.420, respectively. Similarly, the interlayer spacing d of the hard carbon anode materials prepared by the methods in Examples 2 to 6 was calculated after XRD analysis. 002 As shown in Table 1, it can be seen that the interlayer spacing d of the hard carbon anode material prepared by the method of the present invention is... 002 All peaks are greater than 0.37 nm, which are typical characteristic peaks of hard carbon.

[0089] Furthermore, the first charge-discharge curves of the hard carbon anode materials prepared in Examples 1-6 and Comparative Examples 1-2 under 0.1C conditions show that, as shown in Table 1, the platform proportions of the hard carbon anode materials prepared in Comparative Examples 1 and 2 are 27% and 29%, respectively, while the platform proportions of the hard carbon anode materials prepared in Examples 1-6 of this invention are 62-75%. This indicates that the hard carbon anode materials prepared by the preparation method of this invention can further increase their platform proportions.

[0090] Figure 7 , Figure 8 and Figure 9 SEM images of the hard carbon anode materials prepared in Example 1, Comparative Example 1, and Comparative Example 2 are shown below. Figures 7-9 It can be seen that the hard carbon anode material prepared by the method of Example 1 of the present invention exhibits a single-particle morphology with numerous pores on its surface. While the hard carbon anode materials prepared in Comparative Examples 1 and 2 also exhibit a single-particle morphology, they lack pores. Similarly, SEM analysis of the hard carbon anode materials prepared in Examples 2-6 shows that their SEM images are similar to those of the hard carbon anode material in Example 1. This indicates that the hard carbon anode material prepared by the method of the present invention is beneficial for improving the sodium storage performance of the material.

[0091] In summary, this invention discloses a dual-interference chemical preparation method for hard carbon anode materials with high reversible capacity and high plateau ratio. This method involves processing a precursor material formed by mixing biomass carbon source and organic acid salts through ball milling, drying, high-temperature carbonization, cooling, and sieving through a vibrating sieve. This preparation method has the following advantages: (1) Low cost: It uses inexpensive and readily available raw materials, and the experimental process is simple; (2) High carbon yield: The carbon yield of direct high-temperature carbonization of organic acid salts and biomass carbon source is generally no higher than 10%, while the carbon yield in the preparation method of this invention is as high as 50% or more, greatly reducing production costs (the increase in carbon yield is due to: the interaction between organic acid salts and biomass carbon source). During the ball milling process, weak interaction forces (such as van der Waals forces) will be formed between the sources. Due to the existence of weak interaction forces, during the high-temperature carbonization process, organic acid salts rich in H and O elements are more inclined to undergo dehydration condensation (chain reaction) with organic acid salts and biomass carbon sources. The longer the carbon chain, the larger the molecular weight. The larger molecular weight can effectively reduce the loss of precursors during high-temperature carbonization, that is, the carbon production rate of precursor materials after carbonization is improved. (3) The materials used are simple to prepare and highly operable: a one-step sintering method is used, which does not require multi-stage heating and other pretreatments. (4) The preparation process is simple, mainly manifested in the dual interference chemical effect of biomass carbon sources: chemical cross-linking (chemical cross-linking includes biomass organic groups and organic acid salt anionic groups). The chemical bonding reaction between the organic groups and the complexation reaction between the organic groups and metal ions in biomass; the above chemical cross-linking can enable stronger interaction between organic acid salt molecules and biomass macromolecules, and the three-dimensional connection of each molecule makes it difficult for them to be arranged neatly during the high-temperature carbonization process. Instead, it forms a turbulent carbon layer that is more conducive to the diffusion and storage of sodium ions, which is beneficial to improving the overall reversible specific capacity of sodium ions) and pore-forming (the pore-forming effect comes from the interlacing of the turbulent carbon layer caused by chemical cross-linking to form certain sub-nanometer closed pores, and from the formation of a three-dimensional network structure. Some metal ions are bound by the carbon layer, so that a small number of metal ions can only be removed at higher temperatures. The higher removal temperature is conducive to destroying the metal ions that have already been released at low temperatures. The neatly arranged carbon layers form a certain amount of pores with extremely small openings (sub-nanometer scale); both of these pore structures are conducive to the storage of sodium ions on the low potential platform, which is conducive to improving the platform capacity ratio); (5) The prepared product has high morphological consistency: the synthesized material has uniform particle size, which solves the problem of poor consistency of the precursor of lithium-ion battery / sodium-ion battery negative electrode material in the past; (6) High safety: the synthesis process does not need to be sealed, thus avoiding the problem of excessive self-generated pressure during the reaction process, which meets the green chemistry principle of minimizing safety hazards in the chemical production process; (7) High reaction efficiency: the reaction is easy to occur, and the cross-linking reaction of biomass carbon source and organic acid salt and the removal of metal ions and pore formation can be completed in a short time.Therefore, this invention can achieve the following effects through simple dual-interference chemistry: (1) the chemical cross-linking reaction between biomass carbon source and organic acid salt prepares a hard carbon material with high cross-linking degree and high disorder, improving the overall reversible specific capacity; (2) the interaction between biomass and organic acid salt can generate more sub-nanometer-level closed pores or open pores with extremely small opening size inside the material, which is beneficial to increase the sodium storage capacity of the material at low potential plateau and obtain a hard carbon material with high plateau capacity. A hard carbon anode material with high reversible capacity and high plateau ratio was obtained by a series of steps including ball milling, drying, carbonization and sorting of biomass carbon source and organic acid salt. The material preparation of this invention is simple, highly operable and low cost, and the effect is obvious. The hard carbon anode material with high reversible capacity and high plateau ratio prepared by this invention has a reversible capacity of up to 415 mAh / g at 0.1C, excellent sodium storage capacity, huge potential commercial value, and is suitable for promotion and application.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A dual-interference chemical preparation method for a hard carbon anode material with high reversible capacity and high plateau ratio, characterized in that, The dual-interference chemical preparation method includes the following steps: (1) Ball milling: The precursor material formed by mixing biomass carbon source and organic acid salt is placed in a ball mill and ball milled; (2) Drying: Dry the material obtained after ball milling in step (1); (3) Carbonization: The material dried in step (2) is carbonized at high temperature and then cooled to room temperature; (4) Sorting: Pass the cooled material from step (3) through a vibrating screen and sorting equipment to obtain hard carbon anode material with high reversible capacity and high plateau ratio; The biomass carbon source is any one or more of lignin, glucose, sucrose, starch, cotton, coconut shell or straw; The high-temperature carbonized hard carbon anode material is a turbulent carbon layer, which is a carbonization product with high cross-linking degree and high disorder. The turbulent carbon layer is formed by chemical cross-linking of biomass carbon source and organic acid salts, as well as by a double interference effect that assists in pore formation.

2. The dual-interference chemical preparation method according to claim 1, characterized in that, The organic acid salts include any one or more of zinc gluconate, zinc citrate, copper citrate, magnesium gluconate, zinc acetate, sodium gluconate, calcium gluconate, sodium alginate, or potassium oxalate.

3. The dual-interference chemical preparation method according to claim 1, characterized in that, The mass ratio of biomass carbon source to organic acid salt in the precursor material is 1:2 to 1:

10.

4. The dual-interference chemical preparation method according to claim 1, characterized in that, In step (1), a planetary ball mill is used for ball milling, the ball milling speed is 100~500 r / min, the ball milling time is 0.1~48 h, the ball milling solvent is ethanol, deionized water or no ball milling solvent, and the ball milling atmosphere is air, argon or nitrogen.

5. The dual-interference chemical preparation method according to claim 1, characterized in that, In step (2), a vacuum drying oven is used for drying, with a drying temperature of 50~150℃ and a drying time of 2~24h.

6. The dual-interference chemical preparation method according to claim 1, characterized in that, In step (3), the high-temperature carbonization process uses argon, nitrogen, ammonia or hydrogen as the carbonization atmosphere, the high-temperature carbonization temperature is 800~1700℃, the heating rate during the high-temperature carbonization process is 0.5~10℃ / min, and the holding time after heating to the target temperature is 0.5~5h.

7. The dual-interference chemical preparation method according to claim 1, characterized in that, The vibrating screen has a screen mesh size of 100-500 mesh.

8. The hard carbon anode material with high reversible capacity and high plateau ratio prepared by the dual-interference chemical preparation method according to any one of claims 1 to 7.

9. The application of the high reversible capacity and high plateau ratio hard carbon anode material as described in claim 8 in sodium-ion batteries.

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