Asphalt-based hard carbon composite negative electrode material and preparation method and application thereof

Abstract

The application provides a pitch-based hard carbon composite negative material and a preparation method and application thereof, and relates to the technical field of batteries. Specifically, the method comprises the following steps: step one, mixing emulsified pitch and biomass material sufficiently to obtain a composite slurry; and heating the composite slurry to dryness to obtain a composite raw material; step two, pre-oxidizing the composite raw material, and then performing a high-temperature carbonization composite reaction under an inert atmosphere to obtain a negative material. The emulsified pitch and the biomass material are preferentially compounded, and the obtained mixture is pre-oxidized and then high-temperature carbonized and crosslinked. The combination of the two raw materials can well prevent the graphitization of pitch during the carbonization process, and at the same time, a high carbonization rate of the biomass material is realized. The prepared composite negative material has strong electrochemical performance, and has a good application prospect in sodium ion batteries.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically, to an asphalt-based hard carbon composite anode material and its preparation method, a battery anode, and a battery. Background Technology

[0002] Sodium-ion batteries are a new type of rechargeable battery. Their positive electrode material is a sodium-ion compound, and their negative electrode material is carbon. They can achieve an energy density of up to 160 Wh / kg. The working principle of sodium-ion batteries is similar to that of lithium-ion batteries; both achieve charge and discharge through ion exchange between the positive and negative electrodes. Currently, with the development of renewable energy and the electric vehicle industry, sodium-ion batteries (SIBs) have attracted widespread attention as a replacement for lithium-ion batteries (LIBs) due to their low cost and abundant sodium resources.

[0003] Hard carbon refers to carbon that is difficult to graphitize and is obtained from the thermal decomposition of polymers. Common hard carbons include resin carbon, pyrolytic carbon from organic polymers, and carbon black. In the field of sodium-ion battery anode materials, hard carbon materials have advantages such as high capacity, excellent cycle stability, and low-voltage plateau, making them potential ideal candidate materials. However, due to the inherent properties of hard carbon materials, batteries using hard carbon materials still suffer from poor charge-discharge rate performance.

[0004] Biomass materials are considered reliable precursors for large-scale hard carbon production due to their low cost, renewability, and environmental friendliness; however, they suffer from low carbon yield during hard carbon synthesis. Meanwhile, bitumen is also considered a promising carbon precursor due to its high carbon content and abundant resources; however, due to its excellent aromatic hydrocarbon structure, untreated bitumen easily forms a graphite-like structure during carbonization, resulting in low hard carbon yield.

[0005] Currently, crosslinking agents or pre-oxidation methods are commonly used to modify asphalt, hindering the growth of graphite crystals during the pyrolysis and carbonization of asphalt to obtain hard carbon materials. However, these methods suffer from drawbacks such as complex reaction conditions, high cost of organic reactants, and toxicity. If the advantages of biomass materials can be utilized to overcome the shortcomings of asphalt-based hard carbon material preparation, biomass-asphalt composite hard carbon materials will become a highly promising anode material for sodium-ion batteries.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The primary objective of this invention is to provide a method for preparing an asphalt-based hard carbon composite negative electrode material, which involves preferentially compounding emulsified asphalt and biomass materials, and then pre-oxidizing the resulting mixture before high-temperature carbonization and cross-linking. The combined use of the two raw materials can effectively prevent the graphitization of asphalt during the carbonization process, thereby achieving a high carbonization rate for the hard carbon material.

[0008] The second objective of this invention is to provide a method for preparing the asphalt-based hard carbon composite anode material described above, thereby obtaining the asphalt-based hard carbon composite anode material.

[0009] A third objective of this invention is to provide a battery negative electrode, comprising the aforementioned pitch-based hard carbon composite negative electrode material.

[0010] The fourth objective of this invention is to provide a battery that includes the aforementioned battery negative electrode.

[0011] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0012] A method for preparing an asphalt-based hard carbon composite anode material includes the following steps:

[0013] Step 1: Thoroughly mix emulsified asphalt and biomass materials to obtain a composite slurry; heat the composite slurry until it evaporates to dryness to obtain a composite raw material;

[0014] Step 2: The composite raw material is first subjected to pre-oxidation treatment, and then subjected to high-temperature carbonization composite reaction under an inert atmosphere to obtain asphalt-based hard carbon composite anode material.

[0015] The asphalt-based hard carbon composite anode material prepared by the aforementioned method is described. This asphalt-based hard carbon composite anode material can primarily be used as a sodium-ion battery anode, but it can also be used as a lithium-ion battery anode or a potassium-ion battery anode.

[0016] A battery negative electrode includes the aforementioned asphalt-based hard carbon composite negative electrode material, a conductive agent, and a binder. Those skilled in the art can formulate the battery negative electrode raw material according to the conventional amounts of electrode active material, conductive agent, and binder; those skilled in the art can selectively add other functional components to the negative electrode raw material, and this invention does not impose any limitations on this.

[0017] A battery includes the aforementioned negative electrode. Those skilled in the art can arbitrarily combine and select sodium-ion positive electrodes, sodium-ion battery electrolytes, electrolyte additives, separators, or casings to assemble a sodium-ion secondary battery device. This invention does not limit the specific component selection or assembly method. Similarly, those skilled in the art can arbitrarily combine and select lithium-ion battery positive electrodes and their accessories, or potassium-ion battery positive electrodes and their accessories, to obtain a lithium-ion secondary battery device or a potassium-ion secondary battery device.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] (1) The preparation method of the asphalt-based hard carbon composite negative electrode material provided by the present invention greatly simplifies the preparation process of asphalt hard carbon material. The method is simple and easy to implement. It effectively utilizes the advantages of low cost, renewability and environmental protection of biomass materials and achieves a high hard carbon yield of asphalt material.

[0020] (2) The asphalt-based hard carbon composite anode material prepared by the present invention has strong electrochemical performance when used as a sodium-ion battery anode. The reversible capacity is ≥237 mAh / g at a current density of 60 mA / g and the initial coulombic efficiency is ≥78.6%; the discharge specific capacity is ≥143 mAh / g at a high current density of 1.0 A / g. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a graph showing the first charge-discharge curve of the coin cell half-cell prepared in Example 1 of the present invention;

[0023] Figure 2 This is a comparison of the cycle curves of the coin cells prepared in Example 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0025] The present invention is carried out through the following specific embodiments: a method for preparing an asphalt-based hard carbon composite anode material, comprising the following steps: Step 1, thoroughly mixing emulsified asphalt and biomass materials to obtain a composite slurry; heating the composite slurry to dryness to obtain a composite raw material; Step 2, subjecting the composite raw material to pre-oxidation treatment, and then carrying out a high-temperature carbonization composite reaction under an inert atmosphere to obtain the asphalt-based hard carbon composite anode material.

[0026] In this invention, emulsified asphalt is used as raw material. The emulsified liquid nano-asphalt molecules are fully mixed with biomass materials. During the high-temperature carbonization process after pre-oxidation, rearrangement and cross-linking between heterostructures occur, and finally a uniform composite material is obtained.

[0027] In a preferred embodiment, the emulsified asphalt is made by heating and melting asphalt-like substances and then dispersing them in the form of fine particles in an emulsifier or solvent, wherein the slurry particle size of the emulsified asphalt is ≤10μm;

[0028] In a preferred embodiment, the emulsified asphalt includes at least one of cationic emulsified asphalt, anionic emulsified asphalt, and nonionic emulsified asphalt;

[0029] In a preferred embodiment, the solid content of the emulsified asphalt is 50% to 65%.

[0030] In a preferred embodiment, the biomass material includes at least one of crops, oil crops, crop processed products, and agricultural organic residues;

[0031] In a more preferred embodiment, the biomass material includes at least one of potato starch, sweet potato starch, lignin, straw, waste wood powder, and fruit peel.

[0032] In a preferred embodiment, the mass ratio of the emulsified asphalt to the biomass material is 1:(0.1~2). Since there are many types of emulsified asphalt and biomass materials that can be selected in this invention, and the content of effective components they contain is not the same, it is necessary to make a specific measurement of the mass ratio based on the type of emulsified asphalt and the type of biomass material selected.

[0033] In a more preferred embodiment, the mass ratio of the emulsified asphalt to the biomass material includes, but is not limited to, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, and 1:2; the mass ratio can be any of the points listed above, or it can be a range of values ​​formed by the points listed above.

[0034] In a preferred embodiment, in step one, the heating temperature of the composite slurry is 110℃~140℃, and the heating time can be adjusted according to the moisture content of the composite slurry. The heating is carried out until the solvent components of the emulsified asphalt and the moisture carried by the biomass material itself are completely evaporated.

[0035] In a more preferred embodiment, in step one, the heating temperature of the composite slurry includes, but is not limited to, 110, 115, 120, 125, 130, 135, and 140 (°C).

[0036] In a preferred embodiment, in step one, the heating of the composite slurry is carried out under stirring conditions, and the stirring speed is 500 rpm to 800 rpm, including but not limited to 500, 550, 600, 650, 700, 750, and 800 rpm.

[0037] Pre-oxidation treatment modifies the asphalt structure to obtain a cross-linked structure, thereby increasing the disorder of the carbon layer and the interplanar spacing, reducing graphitization in the subsequent carbonization process, and further improving sodium storage performance.

[0038] In a preferred embodiment, in step two, the temperature of the pre-oxidation treatment is 200℃~300℃, and the time of the pre-oxidation treatment is 2h~4h;

[0039] In a more preferred embodiment, in step two, the temperature of the pre-oxidation treatment includes, but is not limited to, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, and 300 (°C), and the time of the pre-oxidation treatment includes, but is not limited to, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, and 4 (h).

[0040] The composite of emulsified asphalt and biomass materials was achieved through carbonization composite reaction. Through a series of composite reactions such as dehydrogenation, condensation, hydrogen transfer and isomerization, gases such as H2, CH4, CO and CO2 were released, and finally an asphalt-based hard carbon composite anode material was formed.

[0041] In a preferred embodiment, in step two, the temperature of the carbonization composite reaction is 1200℃~1400℃, and the time of the carbonization composite reaction is 4h~8h;

[0042] In a more preferred embodiment, in step two, the temperature of the carbonization composite reaction includes, but is not limited to, 1200, 1220, 1240, 1250, 1260, 1280, 1300, 1320, 1340, 1350, 1360, 1380, and 1400 (°C), and the time of the carbonization composite reaction includes, but is not limited to, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, and 8 (h).

[0043] In a preferred embodiment, in step two, the inert gas used in the inert atmosphere includes at least one of nitrogen, helium, neon, or argon.

[0044] As a preferred embodiment, after step two, the method further includes: post-processing of the asphalt-based hard carbon composite negative electrode material, the post-processing including but not limited to grinding, cleaning, and encapsulation.

[0045] A battery negative electrode includes the aforementioned asphalt-based hard carbon composite negative electrode material, a conductive agent, and a binder; in a preferred embodiment, the battery negative electrode serves as the negative electrode of a sodium-ion battery.

[0046] In a preferred embodiment, the conductive agent includes at least one of SPUER P, SO, KS-6, KS-15, SFG-6, SFG-15, 350G, acetylene black (AB), and Ketjen black (KB).

[0047] In a preferred embodiment, when an aqueous solvent phase is used, the adhesive includes at least one of CMC, SBR, PAAs, and PTFE; when an organic solvent phase is used, the adhesive includes PVDF and NMP.

[0048] Example 1

[0049] (1) Weigh 20g of cationic emulsified asphalt with 50% solid content and 20g of potato starch and add them to a beaker. Stir for 10 minutes at a speed of 500r / min to mix thoroughly and obtain a composite slurry. The cationic emulsified asphalt was purchased from Foshan Lichengxin Chemical Co., Ltd. as 70# cationic emulsified asphalt (softening point 47.2℃).

[0050] (2) Place the composite slurry in an oil bath at 120°C and stir at a speed of 500 r / min until no liquid is present to obtain the composite material.

[0051] (3) The composite material is placed in a muffle furnace and kept at 300°C for 4 hours in an air atmosphere to obtain the pre-oxidized material.

[0052] (4) The pre-oxidized material was kept at 1400°C for 6 hours in an argon atmosphere to finally obtain the amorphous hard carbon material prepared in this embodiment.

[0053] Example 2

[0054] (1) Weigh 20g of anionic emulsified asphalt with a solid content of 60% and 20g of lignin and add them to a beaker. Stir for 10 minutes at a speed of 500r / min to mix thoroughly and obtain a composite slurry. The anionic emulsified asphalt was purchased from Xintai Fenglei Chemical Co., Ltd. as 90# anionic emulsified asphalt (softening point 45℃).

[0055] (2) Place the composite slurry in an oil bath at 120°C and stir at a speed of 500 r / min until no liquid is present to obtain the composite material.

[0056] (3) The composite material is placed in a muffle furnace and kept at 220°C for 4 hours in an air atmosphere to obtain the pre-oxidized material.

[0057] (4) The pre-oxidized material was kept at 1400°C for 4 hours in an argon atmosphere to finally obtain the amorphous hard carbon material prepared in this embodiment.

[0058] Example 3

[0059] (1) Weigh 20g of nonionic emulsified asphalt with 60% solid content and 20g of sweet potato starch and add them to a beaker. Stir for 10 minutes at a speed of 500r / min to mix thoroughly and obtain a composite slurry. The nonionic emulsified asphalt was purchased from Guangzhou Yuande Trading Co., Ltd. as 90# nonionic emulsified asphalt (softening point 46℃).

[0060] (2) Place the composite slurry in an oil bath at 120°C and stir at a speed of 500 r / min until no liquid is present to obtain the composite material.

[0061] (3) Place the composite material in a muffle furnace and keep it at 250°C for 4 hours in an air atmosphere to obtain the pre-oxidized material.

[0062] (4) The pre-oxidized material was kept at 1300°C for 8 hours in an argon atmosphere to finally obtain the amorphous hard carbon material prepared in this embodiment.

[0063] Example 4

[0064] (1) Weigh 20g of cationic emulsified asphalt with a solid content of 55% and 20g of macadamia nut shell powder and add them to a beaker. Stir for 10 minutes at a speed of 500r / min to mix thoroughly and obtain a composite slurry. The cationic emulsified asphalt used in this example is the same type as that in Example 1.

[0065] (2) Place the composite slurry in an oil bath at 120°C and stir at a speed of 500 r / min until no liquid is present to obtain the composite material.

[0066] (3) Place the composite material in a muffle furnace and keep it at 200°C for 4 hours in an air atmosphere to obtain the pre-oxidized material.

[0067] (4) The pre-oxidized material was kept at 1400°C for 8 hours in an argon atmosphere to finally obtain the amorphous hard carbon material prepared in this embodiment.

[0068] Example 5

[0069] (1) Weigh 20g of cationic emulsified asphalt with 50% solid content and 20g of glucose and add them to a beaker. Stir for 10 minutes at a speed of 500r / min to mix thoroughly and obtain a composite slurry. The cationic emulsified asphalt used in this example is the same type as that in Example 1.

[0070] (2) Place the composite slurry in an oil bath at 120°C and stir at a speed of 500 r / min until no liquid is present to obtain the composite material.

[0071] (3) Place the composite material in a muffle furnace and keep it at 300°C for 2 hours in an air atmosphere to obtain the pre-oxidized material.

[0072] (4) The pre-oxidized material was kept at 1400°C for 4 hours in an argon atmosphere to finally obtain the amorphous hard carbon material prepared in this embodiment.

[0073] Example 6

[0074] (1) Weigh 20g of cationic emulsified asphalt with a solid content of 65% and 10g of waste straw and add them to a beaker. Stir for 10 minutes at a speed of 500r / min to mix thoroughly and obtain a composite slurry. The cationic emulsified asphalt used in this example is the same type as that in Example 1.

[0075] (2) Place the composite slurry in an oil bath at 110°C and stir at 800 r / min until no liquid is present to obtain the composite material.

[0076] (3) The composite material is placed in a muffle furnace and kept at 300°C for 4 hours in an air atmosphere to obtain the pre-oxidized material.

[0077] (4) The pre-oxidized material was kept at 1200°C for 5 hours in an argon atmosphere to finally obtain the amorphous hard carbon material prepared in this embodiment.

[0078] Example 7

[0079] (1) Weigh 20g of cationic emulsified asphalt with a solid content of 50% and 40g of bamboo and add them to a beaker. Stir for 10 minutes at a speed of 500r / min to mix thoroughly and obtain a composite slurry. The cationic emulsified asphalt used in this example is the same type as that in Example 1.

[0080] (2) Place the composite slurry in an oil bath at 140°C and stir at 500 r / min until no liquid is present to obtain the composite material.

[0081] (3) The composite material is placed in a muffle furnace and kept at 300°C for 4 hours in an air atmosphere to obtain the pre-oxidized material.

[0082] (4) The pre-oxidized material was kept at 1200°C for 7 hours in an argon atmosphere to finally obtain the amorphous hard carbon material prepared in this embodiment.

[0083] Comparative Example

[0084] (1) Weigh 40g of potato starch and put it into the magnetic boat.

[0085] (2) Place potato starch in a muffle furnace and keep it at 300°C for 4 hours in an air atmosphere to obtain the pre-oxidized material.

[0086] (3) The pre-oxidized material was kept at 1400℃ for 6 hours in an argon atmosphere to finally obtain the amorphous hard carbon material prepared in this comparative example.

[0087] Test case

[0088] The hard carbon materials prepared in the various embodiments and comparative examples were mixed with conductive agent superconducting carbon black, binder sodium carboxymethyl cellulose (CMC), and binder styrene-butadiene rubber (SBR) in a mass ratio of 7:1:1:1. A suitable amount of water was added and the mixture was ground into a slurry, which was then coated onto copper foil. The slurry was dried in a vacuum oven at 80°C to obtain the negative electrode. Sodium metal was used as the positive electrode, and the electrolyte was a 1M NaPF6 / (EC+DMC) mixture (volume ratio 1:1). Glass fiber was used as the separator. The 2025-type coin cells were assembled in an argon-filled glove box. Performance tests were conducted on the coin cells prepared based on the various embodiments and comparative examples. The results are shown in Table 1 below. Figure 1 , Figure 2 As shown.

[0089] In addition, the carbon yields of each embodiment and comparative example are also recorded in Table 1.

[0090] Figure 1 The first charge-discharge curves of the coin cell prepared in Example 1 are shown. Figure 1 The paper also gives the initial coulombic efficiency (ICE) of the coin cell as 84.7%. Figure 2 A comparison graph of the cycle curves of the coin cells prepared in Example 1 and Comparative Example 1 is provided.

[0091] Table 1

[0092]

[0093] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing an asphalt-based hard carbon composite anode material, characterized in that, The preparation method includes the following steps: Step 1: Thoroughly mix emulsified asphalt and biomass materials to obtain a composite slurry; heat the composite slurry until it evaporates to dryness to obtain a composite raw material; Step 2: The composite raw material is first subjected to pre-oxidation treatment, and then subjected to high-temperature carbonization composite reaction under an inert atmosphere to obtain asphalt-based hard carbon composite anode material. The biomass material includes at least one of potato starch, sweet potato starch, straw, waste wood powder, and fruit peel; The temperature of the pre-oxidation treatment is 200℃~300℃, and the time of the pre-oxidation treatment is 2h~4h; the temperature of the carbonization composite reaction is 1200℃~1400℃, and the time of the carbonization composite reaction is 4h~8h.

2. The method for preparing the pitch-based hard carbon composite anode material according to claim 1, characterized in that, The emulsified asphalt includes at least one of cationic emulsified asphalt, anionic emulsified asphalt, and nonionic emulsified asphalt; The solid content of the emulsified asphalt is 50% to 65%.

3. The method for preparing the pitch-based hard carbon composite anode material according to claim 1, characterized in that, The mass ratio of the emulsified asphalt to the biomass material is 1:(0.1~2).

4. The method for preparing the pitch-based hard carbon composite anode material according to claim 1, characterized in that, The heating temperature of the composite slurry is 110℃~140℃; The heating of the composite slurry is carried out under stirring conditions, and the stirring speed is 500 rpm to 800 rpm.

5. The asphalt-based hard carbon composite anode material prepared by the method for preparing asphalt-based hard carbon composite anode material according to any one of claims 1 to 4.

6. A battery negative electrode, characterized in that, It includes the asphalt-based hard carbon composite negative electrode material, conductive agent, and binder as described in claim 5.

7. A battery, characterized in that, Includes the battery negative electrode as described in claim 6.

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