Preparation method of high-initial-efficiency hard carbon composite material

Abstract

The application belongs to the technical field of secondary battery material preparation, and particularly relates to a preparation method of high-first-efficiency hard carbon composite material, and the raw materials for preparing the high-first-efficiency hard carbon composite material include, in terms of mass parts, 1-10 parts of organic sodium salt, 100 parts of resin and 1-5 parts of heteroatomic compound; the organic sodium salt is one of sodium m-aminobenzenesulfonate, sodium p-toluenesulfonate, sodium 3-nitrobenzenesulfonate, sodium anthraquinone-1-sulfonate, sodium 1-amino-4-naphthalenesulfonate, sodium hydroxybenzenesulfonate and sodium benzenesulfonate; and the resin is one of epoxy phenolic resin, urea-formaldehyde resin, polysulfone resin, polyester resin, furan resin, furfuryl alcohol resin, furfuryl phenol resin and guanamine resin. The application obtains pre-sodium hard carbon precursors by doping sodium raw materials and heteroatoms in the hard carbon precursors, reduces the irreversible capacity of the material, and improves the first efficiency, power performance and cycle performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of secondary battery material preparation, and particularly relates to a preparation method of a high-first-efficiency hard carbon composite material. BACKGROUND

[0002] Hard carbon is applied to sodium ion or lithium ion batteries due to its high disorder degree, large interlayer spacing and wide material sources. However, oxygen-containing functional groups and other defects growing along the carbon edge or carbon layer in the hard carbon irreversibly capture sodium ions, thereby causing low first coulombic efficiency and poor cycle performance. However, the current measures to improve the first efficiency mainly include reducing material surface defects through material surface coating and improving the specific capacity of the material to improve the first efficiency of the material.

[0003] For example, patent application No. CN202210024891.9 discloses a preparation method of a modified hard carbon negative material with high first coulombic efficiency and related sodium ion batteries. The preparation process is to dissolve pitch material in an organic solvent to prepare a solution with a certain concentration, filter, high-temperature carbonize and crack to prepare a soft and hard carbon composite support carbon film. However, there are problems such as power performance deviation and low first efficiency. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of a high-first-efficiency hard carbon composite material. By doping sodium raw materials and heteroatom dopants in the hard carbon precursor to obtain a pre-sodium hard carbon precursor, the irreversible capacity of the material is reduced, and the first efficiency, power performance and cycle performance are improved.

[0005] The technical solutions adopted by the present application are as follows:

[0006] A high-first-efficiency hard carbon composite material, the raw materials for preparing the high-first-efficiency hard carbon composite material include, by mass fraction:

[0007] 1-10 parts of an organic sodium salt, 100 parts of a resin and 1-5 parts of a heteroatomic compound;

[0008] The organic sodium salt is one of sodium m-aminobenzenesulfonate, sodium p-toluenesulfonate, sodium 3-nitrobenzenesulfonate, sodium anthraquinone-1-sulfonate, sodium 1-amino-4-naphthalenesulfonate, sodium hydroxybenzenesulfonate and sodium naphthalenesulfonate.

[0009] The resin is one of epoxy phenolic resin, urea-formaldehyde resin, polysulfone resin, polyester resin, furan resin, furfuryl alcohol resin, furfuryl phenol resin and guanamine resin.

[0010] The heteroatomic compound is one of triphenyl phosphate, phosphorus oxychloride diphenyl ester, tri-methylphenyl phosphate, butyl diphenyl phosphate, triphenyl phosphite, azobenzene, diazamino benzene and triazobenzene.

[0011] A preparation method of a high-first-efficiency hard carbon composite material, for preparing the high-first-efficiency hard carbon composite material comprises the following steps:

[0012] Step one, dissolving an organic sodium salt, a resin and a heteroatomic compound in chloroform organic solvent to configure a solution;

[0013] Step two, placing the solution into a hydrothermal reaction kettle to perform hydrothermal reaction, and then filtering and vacuum drying to obtain a hard carbon precursor material;

[0014] Step three, transferring the hard carbon precursor material into a tube furnace to perform pre-oxidation treatment;

[0015] Step four, passing a heteroatomic mixed gas into the tube furnace to perform secondary doping to obtain a high-first-efficiency heteroatomic doped hard carbon composite material.

[0016] In a preferred solution, in step one, the mass ratio of the organic sodium salt: resin: heteroatomic compound is 1-10: 100: 1-5.

[0017] In a preferred solution, in step two, the hydrothermal reaction kettle is set to a temperature of 150 DEG C, a pressure of 3 Mpa, and a reaction time of 3 h.

[0018] In a preferred solution, in step two, the vacuum drying temperature is 80 DEG C, and the drying time is 24 h.

[0019] In a preferred solution, in step three, the tube furnace pre-oxidation temperature is 200 DEG C-400 DEG C, the pre-oxidation time is 1 h-6 h, and the temperature rising speed is 1-5 DEG C / min.

[0020] In a preferred solution, in step four, the heteroatomic mixed gas secondary doping time is 1-6 h, and the secondary doping temperature is 1200-1500 DEG C.

[0021] In a preferred solution, in step four, the heteroatomic mixed gas is a mixed gas of a heteroatomic gas and argon, the volume ratio of the heteroatomic gas to argon is 1-5:10, and the heteroatomic gas is one of ammonia, phosphine and diborane.

[0022] In a preferred solution, in step four, the gas flow of the heteroatomic mixed gas passed into the tube furnace to perform secondary doping is 10-100 ml / min.

[0023] The technical effects obtained by the present application are as follows:

[0024] The application improves the transmission rate of sodium ions in the use process of sodium ion batteries by doping organic sodium salt in the hard carbon precursor to obtain a sodium compound after carbonization, and improves the rate performance; meanwhile, the electronic conductivity of the material is improved by doping heteroatoms twice, and the dispersion uniformity between materials is improved by using the hydrothermal method which has the advantages of uniform mixing, high efficiency, etc.

[0025] The application improves the electronic conductivity of the material by doping heteroatoms twice in the core and shell, and improves the rate performance, and meanwhile, the hydrothermal method is used to improve the uniformity of dispersion between materials due to its advantages of uniform mixing, high efficiency, etc.

[0026] The application reduces the surface defects of the material by coating and doping with a heteroatom mixed gas after the outer surface, and improves the initial efficiency of the material. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The SEM diagram of the high-initial-efficiency heteroatom-doped hard carbon composite material prepared in Embodiment 1 of the application. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application will be described in detail below with reference to the drawings.

[0029] In the following description, many specific details are set forth in order to provide a thorough understanding of the application, but the application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the application, therefore the application is not limited by the specific embodiments disclosed below.

[0030] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the application. "In a preferred embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an independent or alternative embodiment that excludes other embodiments.

[0031] Thirdly, the application is described in detail in combination with the schematic diagram, and in the detailed description of the embodiments of the application, the cross-sectional view of the device structure is partially enlarged without general proportion for the convenience of description, and the schematic diagram is only an example, which should not limit the scope of protection of the application herein. In addition, three-dimensional spatial dimensions including length, width and depth should be included in actual manufacturing.

[0032] A high-initial-efficiency hard carbon composite material, the raw materials for preparing the high-initial-efficiency hard carbon composite material include, by mass fraction:

[0033] 1-10 parts of organic sodium salt, 100 parts of resin, and 1-5 parts of heteroatomic compound;

[0034] The organic sodium salt is one of sodium m-aminobenzenesulfonate, sodium p-toluenesulfonate, sodium 3-nitrobenzenesulfonate, sodium anthraquinone-1-sulfonate, sodium 1-amino-4-naphthalenesulfonate, sodium hydroxybenzenesulfonate, and sodium naphthalenesulfonate;

[0035] The resin is one of epoxy phenolic resin, urea-formaldehyde resin, polysulfone resin, polyester resin, furan resin, furfuryl alcohol resin, furfuryl phenol resin, and guanamine resin;

[0036] The heteroatomic compound is one of triphenyl phosphate, diphenyl phosphorochloridate, tri-methylphenyl phosphate, butyl diphenyl phosphate, triphenyl phosphite, azobenzene, diazaminobenzene, and triazobenzene.

[0037] A preparation method of a high-first-efficiency hard carbon composite material, for preparing the high-first-efficiency hard carbon composite material, comprising the following steps:

[0038] S1, dissolving the organic sodium salt, the resin, and the heteroatomic compound in chloroform organic solvent to configure a solution;

[0039] S2, placing the solution into a hydrothermal reaction kettle for hydrothermal reaction, and then filtering and vacuum drying to obtain a hard carbon precursor material;

[0040] S3, transferring the hard carbon precursor material into a tube furnace for pre-oxidation treatment;

[0041] S4, passing a heteroatomic mixed gas into the tube furnace for secondary doping to obtain a high-first-efficiency heteroatomic doped hard carbon composite material.

[0042] In the above steps S1-S4, the organic sodium salt, the resin, and the heteroatomic compound are all in the form of small particles or powder, and after being dissolved in chloroform organic solvent to configure a solution, they are synthesized into a solid through hydrothermal reaction, which has the advantages of uniform mixing, high efficiency, and the like, thereby improving the uniformity of the dispersion between the materials, and the hard carbon precursor material is obtained through filtering and vacuum drying, and after the pre-oxidation treatment of the tube furnace, the sodium raw material in the hard carbon precursor material is carbonized to obtain a sodium compound, which can improve the transmission rate of sodium ions in the process of using the sodium ion battery and improve the rate performance, the heteroatoms doped in the hard carbon precursor material can improve the electronic conductivity of the material and play a synergistic effect between ions and electrons to improve the rate performance of the material, and the hard carbon precursor material after the pre-oxidation treatment is doped with a heteroatomic mixed gas for secondary doping, which can dope the surface of the hard carbon precursor material with heteroatoms, so that the obtained high-first-efficiency heteroatomic doped hard carbon composite material has heteroatoms doped in the core and the shell, which can improve the electronic conductivity of the material and improve the rate performance, and at the same time, the surface of the material can be coated and doped with the heteroatomic mixed gas to reduce the surface defects of the material and improve the first efficiency of the material.

[0043] In a preferred embodiment, in S1, the mass ratio of the organic sodium salt, the resin, and the heteroatomic compound is 1-10:100:1-5.

[0044] In the above, the raw materials are obtained according to the mass ratio of the organic sodium salt, the resin, and the heteroatomic compound, for example, 100g of resin is obtained, and 1-10g of the organic sodium salt and 1-5g of the heteroatomic compound are dissolved in chloroform organic solvent to form a solution.

[0045] In a preferred embodiment, in S2, the hydrothermal reactor is set to a temperature of 150°C and a pressure of 3Mpa, and the reaction time is 3h.

[0046] In the above, the hydrothermal reactor can synthesize the solution under suitable conditions through hydrothermal reaction to make the solution into a solid state.

[0047] In a preferred embodiment, in S2, the vacuum drying temperature is 80°C, and the drying time is 24h.

[0048] In the above, the hard carbon precursor material obtained through vacuum drying does not have liquid residues on the surface, and does not be doped with other substances in a vacuum environment.

[0049] In a preferred embodiment, in S3, the pre-oxidation temperature of the tube furnace is 200-400°C, the pre-oxidation time is 1-6h, and the heating rate is 1-5°C / min.

[0050] In the above, the hard carbon precursor material can be carbonized during the pre-oxidation process, so that the organic sodium salt doped inside is carbonized to obtain a sodium compound, which improves the transmission rate of sodium ions during the use of the sodium ion battery and improves the rate performance.

[0051] In a preferred embodiment, in S4, the secondary doping time of the heteroatomic mixed gas is 1-6h, and the secondary doping temperature is 1200-1500°C.

[0052] In the above, the first efficiency heteroatomic doped hard carbon composite material after the surface doping of the heteroatomic gas can reduce the irreversible capacity of the surface, improve the first efficiency and the electronic conductivity, and improve the power performance and the cycle performance.

[0053] In a preferred embodiment, in S4, the heteroatomic mixed gas is a mixture of the heteroatomic gas and argon, the volume ratio of the heteroatomic gas to argon is 1-5:10, and the heteroatomic gas is one of ammonia, phosphine, and diborane.

[0054] In the above, the heteroatomic mixed gas is one of a mixture of ammonia and argon, a mixture of phosphine and argon, and a mixture of diborane and argon.

[0055] In a preferred embodiment, in S4, the flow rate of the secondary doping gas is 10-100 ml / min.

[0056] Example 1

[0057] 5 g of sodium m-aminobenzenesulfonate, 100 g of epoxy phenolic resin, and 3 g of triphenyl phosphate were dissolved in 500 g of chloroform organic solvent to prepare a solution, and the solution was added to a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction was performed at a temperature of 150°C, a pressure of 3 MPa, and a reaction time of 3 h. The reaction product was then filtered and vacuum dried at 80°C for 24 h to obtain a hard carbon precursor material.

[0058] The hard carbon precursor material was transferred to a tube furnace, and pre-oxidized at a temperature of 300°C at a heating rate of 3°C / min in an air atmosphere for 3 h. Then, ammonia mixed gas (containing ammonia and argon at a volume ratio of 3:10, with a gas flow rate of 50 ml / min) was introduced, and secondary doping was performed at a temperature of 1300°C for 3 h to obtain a high-first-efficiency heteroatom-doped hard carbon composite material.

[0059] Example 2

[0060] 1 g of sodium p-toluenesulfonate, 100 g of urea-formaldehyde resin, and 1 g of phosphorus oxychloride diphenyl ester were dissolved in 500 g of chloroform organic solvent to prepare a solution, and the solution was added to a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction was performed at a temperature of 100°C, a pressure of 5 MPa, and a reaction time of 1 h. The reaction product was then filtered and vacuum dried at 80°C for 24 h to obtain a hard carbon precursor material.

[0061] The hard carbon precursor material was transferred to a tube furnace, and pre-oxidized at a temperature of 200°C at a heating rate of 1°C / min in an air atmosphere for 6 h. Then, phosphine mixed gas (containing phosphine and argon at a volume ratio of 1:10, with a gas flow rate of 10 ml / min) was introduced, and secondary doping was performed at a temperature of 1200°C for 6 h to obtain a high-first-efficiency heteroatom-doped hard carbon composite material.

[0062] Example 3

[0063] Dissolve 10 g of 3-nitrobenzenesulfonic acid sodium, 100 g of furfuryl alcohol resin, and 5 g of butyl diphenyl phosphate in 500 g of chloroform organic solvent to configure a solution, add the solution to a hydrothermal reaction kettle, and perform hydrothermal reaction. The hydrothermal reaction is performed under the condition that the temperature is 200 ℃, the pressure is 1 Mpa, and the reaction time is 1 h. Then, the reaction product is filtered and vacuum dried at 80 ℃ for 24 h to obtain a hard carbon precursor material.

[0064] Transfer the hard carbon precursor material to a tube furnace, and pre-oxidize under an air atmosphere at a temperature rising speed of 5 ℃ / min to 400 ℃. The pre-oxidation time is 1 h. Then, introduce diborane mixed gas (the diborane mixed gas contains diborane and argon, and the volume ratio of diborane to argon is 5:10, and the flow rate is 100 ml / min) to perform secondary doping at a temperature of 1500 ℃ for 1 h to obtain a high first efficiency heteroatom doped hard carbon composite material.

[0065] Comparative Example 1

[0066] Dissolve 100 g of epoxy phenolic resin in 500 g of chloroform organic solvent to configure a solution, add the solution to a hydrothermal reaction kettle, and perform hydrothermal reaction. The hydrothermal reaction is performed under the condition that the temperature is 150 ℃, the pressure is 3 Mpa, and the reaction time is 3 h. Then, the reaction product is filtered and vacuum dried at 80 ℃ for 24 h to obtain a hard carbon precursor material.

[0067] Transfer the hard carbon precursor material to a tube furnace, and pre-oxidize under an air atmosphere at a temperature rising speed of 3 ℃ / min to a temperature of 300 ℃. The pre-oxidation time is 3 h. Then, introduce ammonia mixed gas (the ammonia mixed gas contains ammonia and argon, and the volume ratio of ammonia to argon is 3:10, and the gas flow rate is 50 ml / min) to perform secondary doping at a temperature of 1300 ℃ for 3 h to obtain a high first efficiency heteroatom doped hard carbon composite material.

[0068] Comparative Example 1 is different from Example 1 in that sodium m-aminobenzenesulfonate and triphenyl phosphate are not added when the solution is configured, and the rest is the same as Example 1.

[0069] Comparative Example 2

[0070] Dissolve 5 g of sodium m-aminobenzenesulfonate, 100 g of epoxy phenolic resin, and 3 g of triphenyl phosphate in 500 g of chloroform organic solvent to configure a solution, add the solution to a hydrothermal reaction kettle, and perform hydrothermal reaction. The hydrothermal reaction is performed under the condition that the temperature is 150 ℃, the pressure is 3 Mpa, and the reaction time is 3 h. Then, the reaction product is filtered and vacuum dried at 80 ℃ for 24 h to obtain a hard carbon precursor material.

[0071] The hard carbon precursor material is transferred into a tube furnace, sintered for 6h under an air atmosphere and under an argon atmosphere at 1200℃, to obtain a hard carbon composite material.

[0072] Comparative Example 2 differs from Example 1 in that, after oxidation in an air atmosphere, Example 1 is passed through an ammonia gas mixture, while Comparative Example 2 is passed through argon, and the rest is the same as Example 1.

[0073] The hard carbon composite material with high first efficiency prepared in Example 1 is subjected to SEM testing, and the results are shown in FIG. 1. Figure 1 As can be seen from the figure, the material has a granular structure with a particle size of 10-15μm and uniform size.

[0074] The oil absorption values of the hard carbon composite materials prepared in Examples 1-3 and Comparative Examples 1-2 are tested to characterize the ability of the materials to absorb electrolyte. The method in GB / T7046-2003 “Determination of dibutyl phthalate absorption value of carbon black pigment” is used for determination, and the specific surface area, tap density and OI value of the powder material of the composite material are tested according to GB / T24533-2019 “Graphite-based negative materials for lithium-ion batteries”:

[0075] ;

[0076] As can be seen from Table 1, the tap density and specific surface area of the composite material prepared in the present application are significantly higher than those of Comparative Examples 1-2. The reason is that the electronic conductivity of the material is improved by doping heteroatoms twice in the core and the shell, and the OI value is reduced. At the same time, the hydrothermal method has the advantages of uniform mixing and high density of the obtained material, which improves the tap density of the material.

[0077] The hard carbon composite materials in Examples 1-3 and Comparative Examples 1-2 are respectively assembled into button cells. The assembly method includes adding a binder and a solvent to the composite material, stirring to make a slurry, then coating on a copper foil, and drying and rolling to obtain a pole piece. The binder used is PVDF binder, the solvent is NMP, and the amount ratio is graphene: PVDF: NMP = 80g: 20g: 300ml; the electrolyte is NaPF6 (solvent is EC: DEC: PC: propylene glycol polyoxypropylene ether = 1:2:1:0.05, concentration 1.3mol / L), the metal sodium sheet is the counter electrode, the separator is polyethylene propylene (PEP) composite film, and the assembly is carried out in an argon-filled glove box.

[0078] The electrochemical performance was tested on a Wuhan Lan electric 5V / 10mA battery tester, the charge and discharge voltage range was 0.005V to 2.0V, and the charge and discharge rate was 0.1C. The rate and cycle performance of the material was tested at the same time, the discharge rate was 0.1C / 0.2C / 0.5C / 1C / 2C, and the retention rate of 2C / 0.1C was calculated; the cycle performance of the material was tested at 0.2C / 0.2C, 0.005V-2V, 25±3℃. The DCR of the material was tested at room temperature by discharge test.

[0079] The test results are shown in Table 2:

[0080] ;

[0081] As can be seen from Table 2, the discharge specific capacity and the first efficiency of the battery prepared by using the hard carbon composite material obtained in Examples 1-3 are obviously higher than those of the comparative examples. The reason is that the surface defects of the material are reduced by coating and doping with mixed gas containing heteroatoms after the outer surface, and the first efficiency of the material is improved, and the electronic and ionic conductivity of the material is improved by the heteroatoms and sodium toluenesulfonate and other substances, and the cycle and rate performance is improved.

[0082] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application. The structures, devices and operation methods not specifically described and explained in the present application, such as without special description and limitation, are implemented according to the conventional means in the art.

Claims

1. A method for preparing a high first efficiency hard carbon composite material, characterized by: The raw materials for preparing the high-initial-efficiency hard carbon composite material include, in parts by mass: 1-10 parts of an organic sodium salt, 100 parts of a resin, and 1-5 parts of a heteroatomic compound; The organic sodium salt is one of sodium m-aminobenzenesulfonate, sodium p-toluenesulfonate, sodium 3-nitrobenzenesulfonate, sodium anthraquinone-1-sulfonate, sodium 1-amino-4-naphthalenesulfonate, sodium hydroxybenzenesulfonate, and sodium naphthalenesulfonate; The resin is one of epoxy phenolic resin, urea-formaldehyde resin, polysulfone resin, polyester resin, furan resin, furfuryl alcohol resin, furfuryl phenol resin, and guanamine resin; The heteroatomic compound is one of triphenyl phosphate, phosphorus oxychloride diphenyl ester, phosphoric acid tritolyl ester, butyl diphenyl phosphate, triphenyl phosphite, azobenzene, diazoaminobenzene, and triazobenzene; The steps for preparing the high-initial-efficiency hard carbon composite material are as follows: Step one, dissolving the organic sodium salt, the resin, and the heteroatomic compound in chloroform organic solvent to form a solution; Step two, placing the solution into a hydrothermal reactor for hydrothermal reaction, and then filtering and vacuum drying to obtain a hard carbon precursor material; Step three, transferring the hard carbon precursor material into a tube furnace for pre-oxidation treatment; Step four, introducing a heteroatomic mixed gas into the tube furnace for secondary doping to obtain a high-initial-efficiency heteroatomic doped hard carbon composite material.

2. The method of claim 1, wherein the method comprises: In step one, the mass ratio of the organic sodium salt, the resin, and the heteroatomic compound is 1-10:100:1-5.

3. The method of claim 1, wherein the method comprises: In step two, the temperature of the hydrothermal reactor is set to 150℃, the pressure is 3Mpa, and the reaction time is 3h. ​ 4. The method of claim 1, wherein the method further comprises: In step two, the vacuum drying temperature is 80℃, and the drying time is 24h.

5. The method of claim 1, wherein the method further comprises: In step three, the pre-oxidation temperature of the tube furnace is 200℃-400℃, the pre-oxidation time is 1h-6h, and the temperature rising speed is 1-5℃ / min. ​ 6. The method of claim 1, wherein the method further comprises: In step four, the secondary doping time of the heteroatomic mixed gas is 1-6h, and the secondary doping temperature is 1200-1500℃.

7. The method of claim 1, wherein the method further comprises: In step four, the heteroatomic mixed gas is a mixture of a heteroatomic gas and argon, the volume ratio of the heteroatomic gas to argon is 1-5:10, and the heteroatomic gas is one of ammonia, phosphine, and diborane. ​ 8. The method of claim 1, wherein the method further comprises: In step four, the gas flow rate of the heteroatomic mixed gas introduced into the tube furnace for secondary doping is 10-100mL / min. ​

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