Preparation method of green phenolic resin-based hard carbon negative electrode material and sodium ion battery

Abstract

The invention discloses a preparation method of a green phenolic resin-based hard carbon material and a sodium ion battery. The preparation method of the green phenolic resin-based hard carbon material comprises the following steps: (1) putting a phenol monomer, glyoxylic acid monohydrate, polyethylene glycol and an acid catalyst into an aqueous solution, heating and stirring to obtain a mixed solution; (2) stopping stirring the mixed solution, heating, cross-linking and curing, and centrifugally washing and drying after the reaction is finished to obtain a phenolic resin-based hard carbon precursor; and (3) putting the obtained hard carbon precursor into a high-temperature tubular furnace, and sequentially performing low-temperature presintering and high-temperature carbonization under the protection of inert gas to obtain the green phenolic resin-based hard carbon negative electrode material. The method has the advantages of being environmentally friendly, easy to operate and stable in performance, and the obtained hard carbon material shows high reversible specific capacity, rate capability and long cycle stability.

Description

Technical Field

[0001] The invention relates to a method for preparing one or more sodium ion battery negative electrode materials and a prepared composite material, belonging to the technical field of carbon material and battery material preparation. Background Art

[0002] Energy storage technology can be divided into physical energy storage, chemical energy storage and electromagnetic energy storage according to its working principle. Chemical energy storage, especially electrochemical energy storage, has developed rapidly in recent years due to its advantages such as safety, fast response and high energy density. Lithium-ion batteries have the advantages of high energy density and long cycle life and are currently the most mainstream electrochemical energy storage batteries. Sodium and lithium belong to the same main group and have similar chemical properties. Sodium resources are abundant and have low costs. They have great application prospects in the field of energy storage and have attracted widespread attention from the industry.

[0003] The negative electrode material that has been commercialized in lithium-ion batteries is graphite, but it is difficult to store a large amount of sodium ions in graphite materials, so traditional graphite is difficult to be used as the negative electrode material of sodium-ion batteries. Hard carbon is an amorphous carbon material that is difficult to graphitize even when carbonized at high temperatures (above 2500°C). Hard carbon materials have low potential, wide sources, and low costs. Compared with graphite materials, hard carbon materials have larger interlayer spacing, which is conducive to the insertion / extraction of sodium ions, and have a large number of disordered structures that can provide rich active sites to increase the sodium storage capacity. It is an ideal negative electrode material for sodium-ion batteries. Phenolic resin is considered to be a potential precursor of hard carbon materials with high carbon residue rate, mature production technology, low cost, and excellent electrochemical performance. At present, formaldehyde is mostly used as a raw material in the synthesis of conventional phenolic resins. As we all know, formaldehyde is a highly toxic and carcinogenic substance, and its large-scale use will cause harm to humans and the environment. To solve this problem, this patent uses glyoxylic acid instead of formaldehyde as a raw material for synthesizing phenolic resin. Glyoxylic acid contains aldehyde groups and has high activity. In addition, glyoxylic acid is almost non-toxic and can be naturally extracted from plants, which is more environmentally friendly. The prior art requires hydrothermal / solvothermal operation when preparing phenolic resin from glyoxylic acid, which is cumbersome and not conducive to large-scale production. This patent synthesizes green phenolic resin-based hard carbon by using glyoxylic acid and phenol monomers in the presence of an acidic catalyst and polyethylene glycol, and obtains green phenolic resin-based hard carbon negative electrode materials by simple low-temperature pre-sintering and high-temperature sintering. This invention not only solves the environmental hazards of formaldehyde in the preparation of phenolic resin, but also simplifies the production process, and has the advantages of simple operation, strong universality, and low cost. Summary of the invention

[0004] In view of the harm of formaldehyde to the environment during the synthesis of phenolic resin in the prior art, as well as the problem of complicated production process, the present invention provides a method for preparing a green phenolic resin-based hard carbon negative electrode material, using glyoxylic acid to replace formaldehyde for reaction, and optimizing the material morphology and enhancing its electrochemical properties through acidic catalyst and polyethylene glycol. Simple pre-sintering is used instead of hydrothermal / solvothermal operation. The production process is simplified. The material is used as a negative electrode material for sodium ion batteries, and has high reversible specific capacity, rate performance and long cycle stability.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing a green phenolic resin-based hard carbon negative electrode material for a sodium ion battery comprises the following steps:

[0007] (1) Phenol monomer, glyoxylic acid monohydrate, polyethylene glycol and an acid catalyst are placed in an aqueous solution, heated and stirred to obtain a mixed solution.

[0008] (2) stopping stirring the mixed solution in step (1), heating and crosslinking and curing the mixed solution, and centrifuging and washing and drying the mixed solution after the reaction is completed to obtain a phenolic resin-based hard carbon precursor.

[0009] (3) placing the phenolic resin-based hard carbon precursor obtained in step (2) in a high-temperature tube furnace, and performing low-temperature pre-sintering and high-temperature carbonization in sequence under the protection of an inert gas, thereby obtaining the green phenolic resin-based hard carbon negative electrode material.

[0010] As a preferred embodiment, in step (1), the phenol monomer includes one or more of 3-aminophenol, phenol, resorcinol, phloroglucinol, hydroquinone, and catechol.

[0011] As a preferred embodiment, the molar ratio of the phenol monomer to the glyoxylic acid monohydrate in step (1) is 1:(1-3).

[0012] As a preferred embodiment, the molecular weight of the polyethylene glycol in step (1) is 2000-10000; and the molar ratio of the phenol monomer to the polyethylene glycol is 60:(0-1).

[0013] As a preferred embodiment, the acidic catalyst in step (1) is anhydrous oxalic acid or hydrochloric acid; the mass ratio of the phenol monomer to the acidic catalyst is 100:(1-3).

[0014] As a preferred embodiment, the heating and stirring temperature in step (1) is 25 to 40° C., and the stirring time is 40 to 60 min.

[0015] As a preferred embodiment, in step (2), the curing temperature is 80-100° C. and the curing time is 7-12 hours.

[0016] As a preferred embodiment, the centrifugal washing detergent in step (2) is anhydrous ethanol and water, and the washing is performed alternately for 3 times.

[0017] As a preferred solution, in step (3), the low-temperature pre-sintering temperature is 400-600° C.; the low-temperature pre-sintering holding time is 60-120 min; and the heating rate is 1-10° C. / min.

[0018] As a preferred embodiment, in step (3), the high-temperature carbonization temperature is 1000-1500° C., the heat preservation time is 60-120 min, and the heating rate is 1-10° C. / min.

[0019] A green phenolic resin-based hard carbon negative electrode material is used in sodium ion batteries.

[0020] The beneficial effects of the present invention are:

[0021] 1. Glyoxylic acid is used to replace formaldehyde, which is harmful to the environment, and phenol monomers are subjected to polycondensation reaction under an acidic catalyst environment to synthesize phenolic resin, and polyethylene glycol is used to improve the material morphology and enhance the electrochemical properties of the material. The harm of formaldehyde to the environment during the preparation of phenolic resin is eliminated, and the phenolic resin-based hard carbon negative electrode is applied to the negative electrode of sodium ion batteries, which has high reversible specific capacity, rate performance and long cycle stability.

[0022] 2. The preparation method of the present invention of first low-temperature pre-sintering and then high-temperature carbonization simplifies the preparation process and is more conducive to large-scale preparation.

[0023] 3. This preparation method has the advantages of stable process, easy operation, environmental friendliness and stable performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Attached Figure 1 The scanning electron microscope images of green phenolic resin-based hard carbon with different acidic catalysts and polyethylene glycol addition amounts in Examples 1-3 (a: Example 1, b: Example 2, c: Example 3).

[0025] Attached Figure 2 Green phenolic resin-based hard carbon 30 mA g -1 The first cycle constant current charge and discharge curve under current density.

[0026] Attached Figure 3 This is a graph showing the rate performance of green phenolic resin-based hard carbon with different acidic catalysts and polyethylene glycol addition amounts in Examples 1-3. Attached Figure 4 Green phenolic resin-based hard carbon 300 mA g -1100 cycles performance diagram under current density. DETAILED DESCRIPTION

[0027] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention. However, the present invention is not limited in any form. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention. The present invention is further described in detail below in conjunction with embodiments:

[0028] Example 1

[0029] 1.31g 3-aminophenol, 3.31g glyoxylic acid monohydrate, 0g oxalic acid, 0g polyethylene glycol (molecular weight 6000) were added to 250ml deionized water, stirred at 40℃ for 60min, then heated to 80℃, stopped stirring, and cured at 80℃ for 7h to prepare a phenolic resin solution. The solution was washed alternately with water and anhydrous ethanol by centrifugation for 3 times, placed in a blast drying oven, and dried at 80℃ for 12h. The obtained solid phenolic resin was ground and placed in a tubular furnace, pre-sintered at 600℃ for 2h under nitrogen protection, and then carbonized at 1300℃ for 2h under argon protection to obtain a green phenolic resin-based hard carbon negative electrode material, which was numbered as HC-0.

[0030] The green phenolic resin-based hard carbon material was prepared as the negative electrode of the sodium ion battery and assembled into a button battery. The button battery separator used a glass fiber separator of model GF / D, and the electrolyte was a 1 mol / L NaPF6 ethylene glycol dimethyl ether solution. The assembled battery was left to stand for 8 hours and then subjected to charge and discharge tests on the Blue Electric Battery Test System.

[0031] Example 2

[0032] 1.31g 3-aminophenol, 3.31g glyoxylic acid monohydrate, 0g oxalic acid, 0.6g polyethylene glycol (molecular weight 6000) were added to 250ml deionized water, stirred at 40℃ for 60min, then heated to 80℃, stopped stirring, and cured at 80℃ for 7h to prepare a phenolic resin solution. The solution was washed alternately with water and anhydrous ethanol by centrifugation for 3 times, placed in a blast drying oven, and dried at 80℃ for 12h. The obtained solid phenolic resin was ground and placed in a tubular furnace, pre-sintered at 600℃ for 2h under nitrogen protection, and then carbonized at 1300℃ for 2h under argon protection to obtain a green phenolic resin-based hard carbon negative electrode material, which was numbered as HC-1.

[0033] The green phenolic resin-based hard carbon material was prepared as the negative electrode of the sodium ion battery and assembled into a button battery. The button battery separator used a glass fiber separator of model GF / D, and the electrolyte was a 1 mol / L NaPF6 ethylene glycol dimethyl ether solution. The assembled battery was left to stand for 8 hours and then subjected to charge and discharge tests on the Blue Electric Battery Test System.

[0034] Example 3

[0035] 1.31g 3-aminophenol, 3.31g glyoxylic acid monohydrate, 0.02g oxalic acid, 0.60g polyethylene glycol (molecular weight 6000) were added to 250ml deionized water, stirred at 40°C for 60min, then heated to 80°C, stopped stirring, and cured at 80°C for 7h to prepare a phenolic resin solution. The solution was washed alternately with water and anhydrous ethanol by centrifugation for 3 times, placed in a blast drying oven, and dried at 80°C for 12h. The obtained solid phenolic resin was ground and placed in a tubular furnace, pre-sintered at 600°C for 2h under nitrogen protection, and then carbonized at 1300°C for 2h under argon protection to obtain a green phenolic resin-based hard carbon negative electrode material, which was numbered as HC-2.

[0036] The green phenolic resin-based hard carbon material was prepared as the negative electrode of the sodium ion battery and assembled into a button battery. The button battery separator used a glass fiber separator of model GF / D, and the electrolyte was a 1 mol / L NaPF6 ethylene glycol dimethyl ether solution. The assembled battery was left to stand for 8 hours and then subjected to charge and discharge tests on the Blue Electric Battery Test System.

Claims

1. A method for preparing a green phenolic resin-based hard carbon negative electrode material for a sodium ion battery, characterized in that: The steps include: (1) placing phenol monomer, glyoxylic acid monohydrate, polyethylene glycol and an acid catalyst in an aqueous solution, heating and stirring to obtain a mixed solution; (2) stopping stirring the mixed solution in step (1), heating and crosslinking the mixed solution, and centrifuging and washing and drying the mixed solution after the reaction is completed to obtain a phenolic resin-based hard carbon precursor; (3) The phenolic resin-based hard carbon precursor obtained in step (2) is placed in a high-temperature tube furnace, and under the protection of an inert gas, low-temperature pre-sintering and high-temperature carbonization are performed in sequence to obtain the green phenolic resin-based hard carbon negative electrode material.

2. The preparation method according to claim 1, characterized in that: In the step (1), the phenol monomer includes: one or more of 3-aminophenol, phenol, resorcinol, phloroglucinol, hydroquinone, and catechol; Or, in step (1), the molar ratio of the phenol monomer to the glyoxylic acid monohydrate is 1:(1-3); Or, in step (1), the molecular weight of polyethylene glycol is 2000-10000; the molar ratio of the phenol monomer to polyethylene glycol is 60:(0-1); Or, in step (1), the acidic catalyst is anhydrous oxalic acid or hydrochloric acid; the mass ratio of the phenol monomer to the acidic catalyst is 100:(1-3); Alternatively, the heating and stirring temperature in step (1) is 25-40° C., and the stirring time is 40-60 min.

3. The preparation method according to claim 1, characterized in that: In step (2), the curing temperature is 80-100° C. and the curing time is 7-12 hours; Or, in step (2), the centrifugal washing detergent is anhydrous ethanol and water, and the washing is performed alternately for 3 times; Alternatively, in step (2), the drying environment is vacuum or in air at 80-120° C.; and the drying time is 8-12 hours.

4. The preparation method according to claim 1, characterized in that: In step (3), the inert gas is nitrogen or argon; Or, in step (3), the low-temperature pre-sintering temperature is 400-600°C; the low-temperature pre-sintering holding time is 60-120 min; the heating rate is 1-10°C / min; Alternatively, in step (3), the high temperature carbonization temperature is 1000-1500° C., the heat preservation time is 60-120 min, and the heating rate is 1-10° C. / min.

5. A green phenolic resin-based hard carbon negative electrode material prepared by the method according to any one of claims 1 to 4.

6. Use of the green phenolic resin-based hard carbon negative electrode material described in claim 5 in the preparation of sodium ion batteries.

7. A negative electrode sheet for a sodium ion battery, comprising the green phenolic resin-based hard carbon negative electrode material as claimed in claim 5.

8. A sodium ion battery, comprising the negative electrode sheet for a sodium ion battery according to claim 7.

Images