A high-capacity porous hard carbon composite material, a preparation method and application thereof

Abstract

The application relates to the technical field of secondary battery material preparation, in particular to a high-capacity porous hard carbon composite material and a preparation method and application thereof, the preparation method comprises the following steps: S1. performing a hydrothermal reaction on monosaccharide and an organic metal compound to obtain an intermediate material; S2. passing the intermediate material into an activation gas to form pores to obtain a semi-finished product; mixing the semi-finished product with a crosslinking agent, and carbonizing to obtain the porous hard carbon composite material. The composite material prepared by the application significantly improves the electronic conductivity of the material, reduces the voltage platform and improves the sodium storage performance by using the porous carbon and metal compound formed after carbonization of the organic metal compound. The nano / microporous holes formed by pore forming and crosslinking improve the specific capacity of the platform area, and the application in a sodium ion battery has the characteristics of high specific capacity and good power performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of secondary battery material preparation, and particularly relates to a high-capacity porous hard carbon composite material and a preparation method and application thereof. BACKGROUND

[0002] Sodium-ion batteries are widely used in low-speed electric vehicles, two-wheeled vehicles, energy storage and other fields due to their low cost and excellent low-temperature performance. With the increasing demand for energy density, it is required that the hard carbon negative electrode material used in sodium-ion batteries has higher specific capacity, higher tap density and higher initial efficiency. At present, the main measures to improve the specific capacity are through material pore-making and element doping methods, and the initial efficiency is improved mainly from the perspective of reducing the surface defects of the material and doping sodium.

[0003] Patent application No. CN202210339329.5 discloses a sulfur-phosphorus co-doped hard carbon composite material and a preparation method thereof. The composite material has a core-shell structure, the shell is nitrogen-containing amorphous carbon, the mass fraction of sulfur atoms in the core is 1.11-1.88%, the mass fraction of phosphorus atoms is 1.88-2.23%, and the rest is hard carbon. Although the specific capacity of the obtained material is improved, the specific capacity is still low and the initial efficiency is low. Therefore, it is urgent to develop a high-specific-capacity and high-initial-efficiency hard carbon composite negative electrode material to meet the future demand for high-energy-density hard carbon. SUMMARY

[0004] To improve the specific capacity and initial efficiency of hard carbon, the present application improves the pore and sodium storage performance of the material by doping porous metal compounds in the sugar small molecule hard carbon precursor material, and obtains a hard carbon composite material through gas pore-making, cross-linking and carbonization.

[0005] The first aspect of the present application provides a preparation method of a high-capacity porous hard carbon composite material, which comprises the following steps:

[0006] S1. Hydrothermal reaction of monosaccharide and organic metal compound to obtain an intermediate material;

[0007] S2. Pore-making of the intermediate material by passing into an activation gas to obtain a semi-finished product; mixing the semi-finished product with a cross-linking agent, carbonizing to obtain a porous hard carbon composite material.

[0008] Further, S1 comprises adding monosaccharide into an organic solvent, continuously adding an organic metal compound, and obtaining an intermediate material through hydrothermal reaction at a temperature of 100-200℃, a pressure of 1-5MPa, and a reaction time of 1-6h, followed by filtration and vacuum drying.

[0009] The organic solvent is not particularly limited in the present application, and can be selected from the commonly used types in the art, including but not limited to at least one of toluene, xylene, dichloromethane, trichloromethane, carbon tetrachloride, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide.

[0010] Further, the mass ratio of the monosaccharide, the organic solvent and the organometallic compound is 100:(500-1000):(1-10).

[0011] If the content of the organic compound is too high, the power performance of the material can be improved, but the cycle performance is reduced; if the content of the organic compound is too low, the power performance and the specific capacity of the material are limited. The organic compound in the present application uses an organic sodium salt compound, and sodium-doped porous carbon is obtained after carbonization, thereby improving the specific capacity and the initial efficiency of the material.

[0012] In some embodiments, the monosaccharide includes at least one of erythrose, arabinose, ribose, fructose.

[0013] In some embodiments, the organometallic compound includes at least one of disodium methane disulfonate, sodium o-sulfobenzaldehyde, sodium difluorochloroacetate, sodium 2,4-dichlorophenoxyacetate, sodium n-pentyl xanthate, sodium methanedisulfonate, sodium isooctyl sulfate.

[0014] Further, the S2 includes briquetting the intermediate material at a pressure of 5-15T, introducing an activation gas for pore formation, crushing and dispersing to obtain a semi-finished product; mixing the semi-finished product with a crosslinking agent, and carbonizing at a temperature of 1000-1500℃ for 1-6h to obtain a porous hard carbon composite material.

[0015] In some embodiments, the activation gas includes at least one of carbon dioxide, ammonia and oxygen.

[0016] In some embodiments, the flow rate of the activation gas is 10-100mL / min, and the introduction time is 1-6h.

[0017] If the activation gas is too high, the material has fewer defects, the kinetics is poor, and the rate performance is reduced; if the activation gas is too low, the material has more defects on the surface, and the initial efficiency is low.

[0018] In some embodiments, the mass ratio of the semi-finished product to the crosslinking agent is 100:(1-10).

[0019] In some embodiments, the crosslinking agent includes at least one of furfural, benzaldehyde, trioxane, formaldehyde.

[0020] Compared with other cross-linking agents (imidazole, etc.), the cross-linking agent has low cost, high efficiency, and can form suitable nano / microporous holes, and improve the sodium storage function of the material.

[0021] The second aspect of the application provides a high-capacity porous hard carbon composite material obtained by the above preparation method.

[0022] The third aspect of the application provides an application of the high-capacity porous hard carbon composite material in the preparation of a negative electrode material of a sodium ion battery.

[0023] The fourth aspect of the application provides a battery comprising a negative electrode sheet, wherein the negative electrode sheet comprises the high-capacity porous hard carbon composite material.

[0024] Compared with the prior art, the application has the following beneficial effects:

[0025] The composite material prepared by the application significantly improves the electronic conductivity of the material, reduces the voltage platform, and improves the sodium storage performance by using the porous carbon and metal compounds formed after the carbonization of the organic metal compound. The nano / microporous holes formed by pore making and cross-linking improve the specific capacity of the platform region, and the application in a sodium ion battery has the characteristics of high specific capacity and good power performance. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 SEM image of the high-capacity porous hard carbon composite material prepared for Example 1. DETAILED DESCRIPTION

[0027] The technical solutions in the examples of the application will be described clearly and completely below. Obviously, the described examples are only a part of the examples of the application, but not all the examples. Based on the examples in the application, all other examples obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0028] Example 1

[0029] The example provides a high-capacity porous hard carbon composite material, and the preparation method comprises the following steps:

[0030] S1. 100 g of erythrose is added to 800 g of dimethylbenzene organic solvent, 5 g of methanedisulfonic acid disodium salt is added, and a hydrothermal reaction is carried out under the condition of a temperature of 150 DEG C and a pressure of 3 MPa for 3 h, filtration is carried out, and vacuum drying is carried out at 80 DEG C for 24 h to obtain an intermediate material;

[0031] S2. The intermediate material is briquetted at a pressure of 10T, activated with carbon dioxide gas (flow rate 50 mL / min, for 3h) to form pores, and after crushing and dispersing, a semi-finished product is obtained; 100g of the semi-finished product is mixed with 5g of the furfural crosslinking agent, and heated to 1200°C for carbonization for 3h, to obtain the porous hard carbon composite material.

[0032] Example 2

[0033] The present example provides a high-capacity porous hard carbon composite material, and the preparation method comprises the following steps:

[0034] S1. 100g of arabinose is added to 500g of carbon tetrachloride organic solvent, 1g of o-sulfonic acid sodium benzaldehyde is added, and a hydrothermal reaction is carried out at a temperature of 100°C and a pressure of 5MPa for 6h, filtered, and vacuum dried at 80°C for 24h to obtain an intermediate material;

[0035] S2. The intermediate material is briquetted at a pressure of 5T, activated with ammonia gas (flow rate 10 mL / min, for 1h) to form pores, and after crushing and dispersing, a semi-finished product is obtained; 100g of the semi-finished product is mixed with 1g of the benzaldehyde crosslinking agent, and heated to 1000°C for carbonization for 6h, to obtain the porous hard carbon composite material.

[0036] Example 3

[0037] The present example provides a high-capacity porous hard carbon composite material, and the preparation method comprises the following steps:

[0038] S1. 100g of ribose is added to 1000g of N,N-dimethylformamide organic solvent, 10g of 2,4-dichlorophenoxyacetic acid sodium is added, and a hydrothermal reaction is carried out at a temperature of 200°C and a pressure of 1MPa for 1h, filtered, and vacuum dried at 80°C for 24h to obtain an intermediate material;

[0039] S2. The intermediate material is briquetted at a pressure of 15T, activated with carbon dioxide gas (flow rate 100 mL / min, for 6h) to form pores, and after crushing and dispersing, a semi-finished product is obtained; 100g of the semi-finished product is mixed with 10g of the formaldehyde crosslinking agent, and heated to 1500°C for carbonization for 1h, to obtain the porous hard carbon composite material.

[0040] Comparative Example 1

[0041] The present example provides a high-capacity porous hard carbon composite material, and the preparation method comprises the following steps:

[0042] Comparative Example 2

[0043] The comparative example provides a high-capacity porous hard carbon composite material, the specific implementation is the same as example 1, and the difference is that S2 includes: the intermediate material is briquetted at a pressure of 10T, and the semi-finished product is obtained after crushing and dispersing; 100g of the semi-finished product is uniformly mixed with 5g of the furfural crosslinking agent, heated to 1200℃, and carbonized for 3h to obtain the porous hard carbon composite material.

[0044] Comparative example 3

[0045] The comparative example provides a high-capacity porous hard carbon composite material, the specific implementation is the same as example 1, and the difference is that the methanedisulfonic acid disodium salt is 15g.

[0046] Comparative example 4

[0047] The comparative example provides a high-capacity porous hard carbon composite material, the specific implementation is the same as example 1, and the difference is that the flow rate of the carbon dioxide activation gas is 150mL / min, and the inlet time is 3h.

[0048] Performance test

[0049] 1. SEM test

[0050] The porous hard carbon composite material prepared in example 1 is subjected to SEM test, and the results are shown in Figure 1 As can be seen from the figure, the porous hard carbon composite material prepared in example 1 presents a spherical structure, and the size distribution is uniform, and the particle size is 3-8μm.

[0051] 2. Physicochemical properties and button cell test

[0052] The porous hard carbon composite materials prepared in examples 1-3 and comparative examples 1-4 are subjected to particle size, tap density, specific surface area, and specific capacity and initial efficiency tests. Test method: GBT-24533-2019 "Lithium ion battery graphite negative material". At the same time, the interlayer spacing of the material is tested by XRD.

[0053] The porous hard carbon composite materials obtained in Examples 1-3 and Comparative Examples 1-4 were assembled into button cells A1, A2, A3, B1, B2, B3 and B4, respectively. The preparation method was as follows: a binder, a conductive agent and a solvent were added to the negative electrode material, and stirring was performed to prepare a slurry, which was coated on a copper foil, and then dried and rolled to obtain the button cells. The binder used was LA132 binder, the conductive agent was SP, the negative electrode material was the hard carbon material prepared in Examples 1-3 and Comparative Examples 1-4, and the solvent was double-distilled water, and the ratio was: negative electrode material: SP: LA132: double-distilled water = 94 g: 2 g: 4 g: 220 mL. The electrolyte was NaPF6 / EC+DEC (volume ratio 1:1, concentration 1.1 mol / L), the metal sodium sheet was the counter electrode, and the separator was a polyethylene PE, polypropylene PP or polyethylene propylene PEP composite film. The simulation battery was assembled in an argon-filled glove box, and the electrochemical performance was tested on a Wuhan Lan electric CT2001A battery tester. The charge and discharge voltage range was 0.00 V to 2.0 V, and the charge and discharge rate was 0.1 C. The rate (2C / 0.1C) and cycle performance (0.2C / 0.2C, 200 times) of the button cells were tested, and the test results are shown in Table 1.

[0054] Table 1

[0055]

[0056] As can be seen from Table 1, compared with Comparative Example 1, the first discharge capacity and first efficiency, rate performance and cycle performance of the porous hard carbon composite material prepared in Examples 1-3 are significantly improved. The reason is that, in the present application, the porous carbon and metal compounds formed by carbonization of the organic metal compound in the composite material improve the electronic conductivity of the material, improve the rate performance, and improve the sodium storage performance by pore formation. At the same time, the specific capacity in the platform region is improved by the formation of nano / micropores by cross-linking, and the specific surface area of the material is also improved.

[0057] 3. Soft package battery test:

[0058] The porous hard carbon composite materials in Examples 1-3 and Comparative Examples 1-4 were used as the negative electrode, and slurry mixing and coating were performed to prepare negative electrode sheets. Layered oxides (NaFe 1 / 3 Mn 1 / 3 Ni 1 / 3 O2) were used as the positive electrode, NaPF6 (solvent: EC+DEC, volume ratio 1:1, concentration 1.3 mol / L) was used as the electrolyte, and celegard2400 was used as the separator to prepare 2 Ah soft package batteries.

[0059] High temperature storage performance test:

[0060] Test method: Test condition: test its battery full capacity at 60 DEG C for X1, then after 30 days at 60 DEG C, then test its battery capacity for X2, calculate the charge retention = X2 / X1*100%; then make its battery full charge to full state (100% SOC), test its battery capacity for X3, calculate the recovery capacity = X3 / X1*100%;

[0061] Cycle performance: temperature 25 DEG C, 1C / 1C, 500 cycles.

[0062] Rate performance: constant current + constant voltage charging at 2C+0.1C to 4.0C, then calculate the battery constant current ratio = 2C constant current capacity / (2C constant current capacity + 0.1C constant voltage capacity)

[0063] The results are shown in Table 2.

[0064] Table 2

[0065] Examples Charge retention Capacity recovery Cycle performance Constant current ratio Example 1 94.6％ 96.1％ 95.5％ 95.4％ Example 2 94.5％ 97.3％ 95.1％ 94.9％ Example 3 94.9％ 96.5％ 95.8％ 95.8％ Comparative Example 1 90.3％ 92.3％ 92.3％ 87.3％ Comparative Example 2 91.5％ 93.4％ 92.9％ 88.8％ Comparative Example 3 91.8％ 93.9％ 94.1％ 86.3％ Comparative Example 4 90.0％ 92.1％ 91.4％ 89.9％

[0066] As can be seen from Table 2, the high temperature storage performance and rate performance of the material of the example are better than those of the comparative example, because the surface of the material is modified by a crosslinking agent gas to reduce the surface defects and improve the high temperature storage performance, and the electronic conductivity of the material is improved by doping a homologous compound to improve the constant current ratio.

[0067] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a high-capacity porous hard carbon composite material, characterized by, The preparation method comprises the following steps: S1. subjecting a monosaccharide and an organic metal compound to a hydrothermal reaction to obtain an intermediate material, the organic metal compound comprising at least one of methanedisulfonic acid disodium salt, o-sulfonic acid sodium benzaldehyde, sodium difluorochloroacetate, 2,4-dichlorophenoxyacetic acid sodium, n-pentyl sodium xanthate, methyl disulfonic acid sodium, isooctyl sodium sulfate; S2. subjecting the intermediate material to a pore-forming activation gas to obtain a semi-finished product; mixing the semi-finished product with a crosslinking agent, carbonizing to obtain a high-capacity porous hard carbon composite material.

2. The production method according to claim 1, characterized by, The monosaccharide comprises at least one of erythrose, arabinose, ribose, fructose.

3. The method of any one of claims 1, 2, wherein, The activation gas comprises at least one of carbon dioxide, ammonia, oxygen.

4. The production method according to claim 3, characterized by, The flow rate of the activation gas is 10-100 mL / min, and the time of the activation gas is 1-6 h.

5. The preparation method according to claim 1, characterized in that, The mass ratio of the semi-finished product to the crosslinking agent is 100: (1-10).

6. The production method according to claim 5, wherein The crosslinking agent comprises at least one of furfural, benzaldehyde, trioxane, formaldehyde.

7. A high capacity porous hard carbon composite material, characterized by, The high-capacity porous hard carbon composite material is prepared by the preparation method of any one of claims 1-6.

8. The use of the high-capacity porous hard carbon composite material of claim 7 in the preparation of a sodium ion battery negative electrode material.

9. A battery, characterized by The negative electrode sheet comprises the high-capacity porous hard carbon composite material of claim 7.

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