Preparation method and application of modified epoxy resin-based hard carbon negative electrode material

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Through the preparation method of modified epoxy resin-based hard carbon negative electrode material, the problem of low efficiency and capacity of existing hard carbon negative electrode materials in sodium ion batteries is solved, and efficient carbonization yield and electrochemical performance improvement are achieved.

CN119569028APending Publication Date: 2025-03-07HUNAN UNIV

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Patent Information

Application Number: CN202411745311.0
Authority / Receiving Office: CN · China
Patent Type: Applications(China)
Current Assignee / Owner
Filing Date: 2024-12-02
Publication Date: 2025-03-07

AI Technical Summary

Technical Problem

The existing hard carbon anode materials have low first-time efficiency and low reversible capacity in sodium ion batteries, and the carbon yield of biomass-based hard carbon is low, which limits production capacity and increases costs.

Method used

Modified epoxy resin is used as the precursor, and the modified epoxy resin is heated in deionized water and diammonium hydrogen phosphate is added, and the modified epoxy resin-based hard carbon negative electrode material is obtained.

Benefits of technology

The first Coulomb efficiency and reversible capacity of hard char material were improved, the carbonization yield was significantly improved, from 22% to 35%, and the process was simplified, environmentally friendly and efficient.

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Abstract

The invention relates to a preparation method and application of a modified epoxy resin-based hard carbon negative electrode material, in particular to a hard carbon negative electrode material obtained by deriving diammonium hydrogen phosphate serving as a curing cross-linking agent and a nitrogen and phosphorus atom doping agent of epoxy resin. The preparation method mainly comprises the following steps: dispersing epoxy resin and diammonium hydrogen phosphate in deionized water, uniformly mixing, then placing the mixture in an air dry oven for curing and crosslinking, then placing the cured epoxy resin in a tubular furnace in an inert atmosphere, and sequentially carrying out low-temperature pre-carbonization and high-temperature carbonization, and finally, carrying out ball milling treatment on the obtained product to obtain the modified epoxy resin-based hard carbon negative electrode material. The process for preparing the epoxy resin-based hard carbon negative electrode material is environment-friendly, the process is simple, the carbonization yield is obviously improved, and the electrochemical test shows that the hard carbon material prepared by the method has relatively high first coulombic efficiency and reversible capacity. The method plays a positive role in promoting wide application of the sodium ion battery in the new energy industry.

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Description

Technical Field

[0001] The present invention belongs to the technical field of battery material preparation, and relates to a preparation method and application of a modified epoxy resin-based hard carbon material. Background Art

[0002] Lithium-ion batteries have been widely used in the field of energy storage due to their high safety, high energy density and excellent cycle stability. However, due to the scarcity of lithium resources and the rise in prices, lithium-ion batteries cannot meet the huge demand for batteries in society today. Therefore, there is an urgent need to find alternatives to lithium-ion batteries. Sodium-ion batteries have attracted widespread attention due to the low price and abundant reserves of sodium metal and the similar working principle to lithium-ion batteries. However, sodium ions have a larger radius than lithium ions, so they are not suitable for embedding in graphite. Therefore, the development of suitable negative electrode materials is a major challenge for the application of sodium-ion batteries.

[0003] Hard carbon has a large carbon layer spacing, abundant graphite nanodomains and a unique pore structure, which is conducive to the embedding / de-embedding of sodium ions. It also has small volume expansion, good safety and stable structure. Therefore, hard carbon is considered to be the most promising negative electrode material. However, the hard carbon negative electrode materials currently developed have the disadvantages of low first efficiency and low reversible capacity. For example, the first efficiency of hard carbon prepared by pyrolysis of phenolic aldehyde, furfural, asphalt and other materials is only 40%-60%, and the reversible capacity is less than 300mAh / g. In addition, the carbon yield of hard carbon is also low. For example, the carbon yield of biomass-based hard carbon is only 10-20wt.%, which limits production capacity and increases costs. Therefore, it is also very important to improve the carbon yield of biomass-based hard carbon materials while improving the sodium storage performance of hard carbon materials. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing a modified epoxy resin-based hard carbon negative electrode material and its application in sodium ion batteries. The process of the present invention is environmentally friendly, simple in process, and the carbonization yield is significantly improved, and the modified hard carbon material exhibits a higher first coulombic efficiency and reversible capacity.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides a method for preparing a hard carbon negative electrode material for a sodium ion battery, comprising the following steps:

[0007] a. Disperse the epoxy resin in a certain volume of deionized water and heat to boiling, then add diammonium hydrogen phosphate and stir evenly; b. Transfer the mixture solution obtained in step a to a forced air drying oven, heat and cure it for cross-linking, and obtain the modified epoxy resin; c. Under the protection of an inert atmosphere, the modified epoxy resin obtained in step b is subjected to low-temperature pre-carbonization, high-temperature carbonization and ball milling treatment in sequence to obtain a modified epoxy resin-based hard carbon negative electrode material.

[0008] Furthermore, in step a, the epoxy resin includes one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, polyphenol glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin, and glycidyl ester epoxy resin.

[0009] Furthermore, in step a, the mass ratio of diammonium hydrogen phosphate to epoxy resin is 0.1%-100%.

[0010] Furthermore, in step a, the usage ratio of the epoxy resin to deionized water is 1g / 1mL-1g / 50mL.

[0011] Furthermore, in step c, the low-temperature pre-carbonization is: heating to 400-800° C. at a heating rate of 1-10° C. / min, and heat preservation for 1-2 hours;

[0012] Furthermore, in step c, the high temperature carbonization is: heating to 1000-1600° C. at a heating rate of 1-10° C. / min and heat preservation for 1-3 hours;

[0013] Furthermore, in step c, the ball milling treatment is performed so that the hard carbon after ball milling can pass through a 200-500 mesh sieve.

[0014] The second aspect of the present invention provides a modified epoxy resin-based hard carbon negative electrode material prepared by the above-mentioned preparation method.

[0015] The third aspect of the present invention is the use of the modified epoxy resin-based hard carbon negative electrode material in the preparation of a sodium ion battery.

[0016] The fourth aspect of the present invention is the application of the above-mentioned modified epoxy resin-based hard carbon negative electrode material in sodium ion batteries, and the application fields include electric vehicles, mobile phones, laptops, electronic products, and mobile energy storage equipment manufacturing.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention provides a method for preparing a modified epoxy resin-based hard carbon negative electrode material for a sodium ion battery and its application in a sodium ion battery. The process is environmentally friendly, the process is simple, and the modified hard carbon material exhibits a high first coulombic efficiency and reversible capacity. In the present invention, when epoxy resin and diammonium hydrogen phosphate are used as precursors, diammonium hydrogen phosphate will not only be in-situ doped, but also be cured and cross-linked, thereby changing the properties and structure of the precursor, affecting the interlayer spacing, specific surface area, pore structure, degree of graphitization, etc. of the hard carbon, thereby improving the electrochemical performance of the hard carbon negative electrode material for the sodium ion battery and effectively improving the carbon yield. The prepared phenolic resin-based hard carbon negative electrode material has a first coulombic efficiency of 85% and a reversible capacity of 321mAh / g at 1mol / L NaPF6-EC / DEC as an electrolyte and a current density of 30mAh. After 100 cycles at a rate of 0.2C, the capacity remains above 98%. In addition, the carbonization yield of the hard carbon negative electrode material prepared by the present invention is significantly improved, and its carbon yield is increased from 22% to 35%. In short, the modified epoxy resin-based hard carbon negative electrode material prepared by the present invention is expected to be widely used in sodium ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the first charge and discharge curve at 0.1C of the modified epoxy resin-based hard carbon material prepared in Example 1 of the present application.

[0020] Figure 2 This is the P1S spectrum in XPS of the modified phenolic resin-based hard carbon material prepared in Example 1.

[0021] Figure 3 This is the N1S spectrum in XPS of the modified phenolic resin-based hard carbon material prepared in Example 1. DETAILED DESCRIPTION

[0022] In the specific implementation process, the present invention proposes a method for preparing a modified epoxy resin-based hard carbon negative electrode material, comprising the following steps: a. dispersing epoxy resin in a certain volume of deionized water and heating to boiling, then adding diammonium hydrogen phosphate and stirring evenly; b. transferring the mixture solution obtained in step a to a blast drying oven, and heating to cure and crosslink to obtain a modified epoxy resin; c. under the protection of an inert atmosphere, the modified epoxy resin obtained in step b is subjected to low-temperature pre-carbonization, high-temperature carbonization and ball milling treatment in sequence to obtain a modified epoxy resin-based hard carbon negative electrode material. According to another aspect of the present invention, the hard carbon negative electrode material of the present invention is applied to a sodium ion battery and a negative electrode sheet is provided, which combines the characteristics of the sodium ion battery to give full play to its material performance advantages. The negative electrode sheet is a mixed slurry containing the aforementioned hard carbon negative electrode material or the hard carbon negative electrode material prepared by the aforementioned method and a conductive agent and a binder, and is coated on a metal foil, preferably a copper foil.

[0023] The present invention is further described below in conjunction with specific examples, but the present invention is not limited to the following examples. The methods described are conventional methods unless otherwise specified. The raw materials described can be obtained from public commercial channels unless otherwise specified.

[0024] Example 1

[0025] This embodiment relates to a preparation method and application of a modified epoxy resin-based hard carbon negative electrode material. The specific steps are as follows:

[0026] a Disperse 1 g of epoxy resin in 5 mL of deionized water and heat to 100 °C, then add 0.1 g of diammonium hydrogen phosphate and stir well.

[0027] b. Transfer the mixture solution obtained in step a to a forced air drying oven, and cure and crosslink at 110° C. for 2 h to obtain a cured and modified epoxy resin.

[0028] c Under the protection of argon atmosphere, the cured modified epoxy resin obtained in step b is heated to 600°C at a heating rate of 5°C / min and kept warm for 1 hour, then heated to 1350°C at 5°C / min and kept warm for 2 hours. After cooling to room temperature, the obtained carbonized product is ball-milled and passed through a 300-mesh sieve to obtain the modified epoxy resin-based hard carbon negative electrode material.

[0029] Example 2

[0030] This embodiment relates to a preparation method and application of a modified epoxy resin-based hard carbon negative electrode material. The specific steps are as follows:

[0031] a Disperse 1 g of epoxy resin in 5 mL of deionized water and heat to 100 °C, then add 0.05 g of diammonium hydrogen phosphate and stir well.

[0032] b. Transfer the mixture solution obtained in step a to a forced air drying oven, and cure and crosslink at 110° C. for 2 h to obtain a cured and modified epoxy resin.

[0033] c Under the protection of argon atmosphere, the cured modified epoxy resin obtained in step b is heated to 600°C at a heating rate of 5°C / min and kept warm for 1 hour, then heated to 1350°C at 5°C / min and kept warm for 2 hours. After cooling to room temperature, the obtained carbonized product is ball-milled and passed through a 300-mesh sieve to obtain the modified epoxy resin-based hard carbon negative electrode material.

[0034] Example 3

[0035] This embodiment relates to a preparation method and application of a modified epoxy resin-based hard carbon negative electrode material. The specific steps are as follows:

[0036] a Disperse 1 g of epoxy resin in 5 mL of deionized water and heat to 100 °C, then add 0.1 g of diammonium hydrogen phosphate and stir well.

[0037] b. Transfer the mixture solution obtained in step a to a forced air drying oven, and cure and crosslink at 110° C. for 2 h to obtain a cured and modified epoxy resin.

[0038] c Under the protection of argon atmosphere, the cured modified epoxy resin obtained in step b is heated to 600°C at a heating rate of 5°C / min and kept warm for 1 hour, then heated to 1200°C at 5°C / min and kept warm for 2 hours. After cooling to room temperature, the obtained carbonized product is ball-milled and passed through a 300-mesh sieve to obtain the modified epoxy resin-based hard carbon negative electrode material.

[0039] Comparative Example 1

[0040] This comparative example is substantially the same as Example 1, except that diammonium hydrogen phosphate is not added in this comparative example.

[0041] The specific steps are as follows:

[0042] a Disperse 1 g of epoxy resin in 5 mL of deionized water and heat to 100 °C.

[0043] b. Transfer the mixture solution obtained in step a to a forced air drying oven and keep it at 110° C. for 2 h.

[0044] c Under the protection of argon atmosphere, the epoxy resin obtained in step b was heated to 600°C at a heating rate of 5°C / min and kept warm for 1h, then heated to 1350°C at 5°C / min and kept warm for 2h. After cooling to room temperature, the obtained carbonized product was ball-milled and passed through a 300-mesh sieve to obtain an epoxy resin-based hard carbon negative electrode material.

[0045] Comparative Example 2

[0046] This comparative example is substantially the same as Example 1, except that diammonium hydrogen phosphate is replaced by ammonium phosphate in this comparative example.

[0047] The specific steps are as follows:

[0048] a Disperse 1 g of epoxy resin in 5 mL of deionized water and heat to 100 °C, then add 0.1 g of ammonium phosphate and stir well.

[0049] b. Transfer the mixture solution obtained in step a to a forced air drying oven, and cure and crosslink at 110° C. for 2 h to obtain a cured and modified epoxy resin.

[0050] c Under the protection of argon atmosphere, the cured modified epoxy resin obtained in step b is heated to 600°C at a heating rate of 5°C / min and kept warm for 1 hour, then heated to 1350°C at 5°C / min and kept warm for 2 hours. After cooling to room temperature, the obtained carbonized product is ball-milled and passed through a 300-mesh sieve to obtain the modified epoxy resin-based hard carbon negative electrode material.

[0051] Comparative Example 3

[0052] This comparative example is substantially the same as Example 1, except that diammonium hydrogen phosphate is replaced by phosphoric acid in this comparative example.

[0053] The specific steps are as follows:

[0054] a Disperse 1 g of epoxy resin in 5 mL of deionized water and heat to 100 °C, then add 0.1 g of phosphoric acid and stir well.

[0055] b. Transfer the mixture solution obtained in step a to a forced air drying oven, and cure and crosslink at 110° C. for 2 h to obtain a cured and modified epoxy resin.

[0056] c Under the protection of argon atmosphere, the cured modified epoxy resin obtained in step b is heated to 600°C at a heating rate of 5°C / min and kept warm for 1 hour, then heated to 1350°C at 5°C / min and kept warm for 2 hours. After cooling to room temperature, the obtained carbonized product is ball-milled and passed through a 300-mesh sieve to obtain the modified epoxy resin-based hard carbon negative electrode material.

[0057] Negative electrode preparation

[0058] The hard carbon, conductive agent Super P, and binder (CMC) prepared in Examples 1-3 and Comparative Examples 1-3 were mixed in a mass ratio of 85:10:5 and coated on the current collector copper foil, vacuum dried at 80° C. for 8 h, pressed at a pressure of 1 MPa, and punched into a negative electrode sheet.

[0059] Performance Testing

[0060] The negative electrode sheets prepared in Examples 1-3 and Comparative Examples 1-3 were used as negative electrodes, and metallic sodium was used as the counter electrode to assemble CR2032 button cells in an inert atmosphere. The electrolyte was 1MNaPF6-EC / DEC (volume ratio 1:1). The button cell structure included a positive electrode shell (stainless steel), a negative electrode shell (stainless steel), a gasket (stainless steel), a spring (stainless steel), a hard carbon electrode, a sodium sheet, an electrolyte, and a diaphragm (glass fiber).

[0061] The electrochemical performance test was carried out at 25°C, with a discharge cut-off voltage of 0 V and a charge cut-off voltage of 3 V. The specific results are shown in Table 1 1C = 300 mAh / g.

[0062] Table 1

[0063]

[0064] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Therefore, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a modified epoxy resin-based hard carbon negative electrode material, comprising the following steps: a. dispersing epoxy resin in a certain volume of deionized water and heating to boiling, then adding diammonium hydrogen phosphate and stirring evenly; b. transferring the mixture solution obtained in step a to a forced air drying oven, and heating to cure and cross-link to obtain a modified epoxy resin; c. under the protection of an inert atmosphere, subjecting the modified epoxy resin obtained in step b to low-temperature pre-carbonization, high-temperature carbonization and ball milling treatment in sequence to obtain a modified epoxy resin-based hard carbon negative electrode material.

2. The method for preparing a modified epoxy resin-based hard carbon negative electrode material according to claim 1, characterized in that In step a, the epoxy resin includes one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, polyphenol glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin, and glycidyl ester epoxy resin.

3. The method for preparing a modified epoxy resin-based hard carbon negative electrode material according to claim 1 or 2, characterized in that In step a, the mass ratio of diammonium hydrogen phosphate to epoxy resin is 0.1%-100%.

4. A method for preparing a modified epoxy resin-based hard carbon negative electrode material according to any one of claims 1 to 3, characterized in that : In step a, the usage ratio of the epoxy resin to deionized water is 1g / 1mL-1g / 50mL.

5. A method for preparing a modified epoxy resin-based hard carbon negative electrode material according to any one of claims 1 to 4, characterized in that In step c, the low-temperature pre-carbonization is to heat the material to 400-800°C at a heating rate of 1-10°C / min and keep the temperature for 1-2 hours.

6. A method for preparing a modified epoxy resin-based hard carbon negative electrode material according to any one of claims 1 to 5, characterized in that In step c, the high temperature carbonization is: heating to 1000-1600°C at a heating rate of 1-10°C / min and heat preservation for 1-3h.

7. A method for preparing a modified epoxy resin-based hard carbon negative electrode material according to any one of claims 1 to 6, characterized in that In step c, the ball milling process is to allow the hard carbon after ball milling to pass through a 200-500 mesh sieve.

8. A modified epoxy resin-based hard carbon negative electrode material prepared according to any of the methods described in claims 1-7.

9. Use of the modified epoxy resin-based hard carbon negative electrode material according to claim 8 in the preparation of sodium ion batteries.

10. The use of the modified epoxy resin-based hard carbon negative electrode material according to claim 8 or 9 in sodium ion batteries, wherein the application fields include electric vehicles, mobile phones, laptop computers, electronic products, and mobile energy storage device manufacturing.