Preparation method of sodium-based modified phenolic resin hard carbon negative electrode

Abstract

The application discloses a preparation method of sodium-based modified phenolic resin and belongs to the field of sodium ion batteries. The method comprises the following steps: obtaining amino-phenolic resin by condensation reaction of phenolic compounds and aldehyde compounds under the action of an alkaline catalyst; obtaining neutralization reaction of 5-amino-1.2.3-benzene tricarboxylic acid and sodium hydroxide solution; and obtaining sodium-based modified phenolic resin by addition reaction of organic solvent, amino-phenolic resin, triethylamine and epoxy propylene aldehyde diethyl glycol. The application further provides a preparation method of sodium-based modified phenolic resin hard carbon negative electrode, which comprises the following steps: carbonizing and grinding the sodium-based modified phenolic resin under an inert atmosphere, and screening to obtain active material; uniformly mixing the active material, a conductive agent and a binder, and coating on a copper foil, and then drying and rolling to obtain a sodium ion battery negative electrode sheet. The method effectively improves the capacity and the first cycle coulombic efficiency of the hard carbon negative electrode, thereby effectively improving the electrochemical performance of the sodium ion battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of sodium ion batteries, and particularly relates to a preparation method of a sodium-based modified phenolic resin hard carbon negative electrode. BACKGROUND

[0002] As a new emerging electrochemical energy storage system, sodium ion batteries have great development potential and are expected to replace lithium ion batteries in the context of the rapid development of global new energy vehicles. Compared with lithium ion batteries, sodium ion batteries have more abundant reserves, higher theoretical capacity and lower production cost.

[0003] With the rise of sodium ion batteries, hard carbon materials have attracted widespread attention. Commercial hard carbon is commonly used to improve the low-temperature fast-charging performance of lithium ion batteries. Currently, the commonly used hard carbon precursors are mainly bio-based polymer materials such as bamboo, coconut shell, starch, walnut shell, etc. In addition, chemical raw materials such as anthracite, pitch and phenolic resin can also be used.

[0004] For sodium ion batteries, the structural characteristics and preparation process of hard carbon materials have an important influence on the electrical performance of the battery. Generally, hard carbon negative materials have high specific capacity, which means that under the same volume or mass, hard carbon negative materials can store more sodium ions, thereby improving the energy density and endurance of the battery. On the other hand, hard carbon materials have large pore structures, making the expansion and contraction of the electrode more uniform during charging and discharging, thereby enhancing the cycle stability of the battery.

[0005] However, although hard carbon negative materials have good stability, their cycle performance is poor, especially under high-rate charging and discharging conditions. In addition, the first-cycle coulombic efficiency of hard carbon negative materials is relatively low, resulting in a large energy loss during the first charging and discharging process, which affects the overall performance of the battery.

[0006] In view of the above problems, the patent document with publication number CN117352652A (published on January 5, 2024) discloses a preparation method and application of a high-performance sodium-ion battery hard carbon negative material, including the following steps: 1) pitch crushing process: weigh the pitch, use a powder machine to obtain pitch particles with a particle size of 1-50 μm; 2) introduction of crosslinking agent process: the pitch particles obtained in step 1) are subjected to pretreatment for 2-30 h in a tube furnace to capture the crosslinking agent in the gas, obtaining crosslinked pitch; 3) carbonization process: the crosslinked pitch obtained in step 2) is placed in a tube furnace under the protection of a protective gas, and after cooling, a hard carbon material is obtained; 4) hard carbon material particle size control process: the hard carbon material obtained in step 3) is used to obtain hard carbon particles with a particle size of 1-50 μm using a powder machine, and then a sieve is used to screen the desired 8-10 μm hard carbon particles; 5) the hard carbon particles obtained in step 4) are mixed with a binder and conductive carbon black to obtain a mixed negative material, the mixed negative material is mixed with water and stirred to obtain a mixed slurry, the mixed slurry is coated on a current collector, and after drying, a high-performance sodium-ion battery hard carbon negative material is obtained.

[0007] The invention uses pitch as the precursor of hard carbon, which can significantly reduce the cost, but the invention does not involve the improvement of the microstructure of the hard carbon negative material, and there is no significant improvement in the electrical performance of the formed sodium-ion battery, such as the first cycle coulombic efficiency and cycle stability.

[0008] The patent document with publication number CN117163940A (published on December 5, 2023) discloses a P, O co-doped sodium-ion battery hard carbon negative material and a preparation method thereof, the method comprising: crushing and sieving raw material pitch after high-energy ball milling; removing impurities by acid / alkali washing, then washing with deionized water and drying to obtain pure pitch powder; mixing the pitch powder, organic phosphorus source and alcohol uniformly according to a certain proportion, then transferring into a crucible and transferring into a tube furnace; heating according to a certain heating rate, holding, and cooling according to a certain cooling rate; after the tube furnace is completely cooled, the crucible is taken out, the material is ground and sieved to obtain a P, O co-doped pitch-based carbon negative material.

[0009] The invention constructs a sodium-ion battery by synthesizing a P, O co-doped pitch-based carbon negative material, but the pitch-based carbon negative material may introduce some defects and functional groups during the preparation process, and these defects and functional groups may have irreversible reactions with the electrolyte during the first charge and discharge process, resulting in capacity loss of the battery, and the conductivity of the pitch-based carbon negative material is poor, which affects the electronic transmission efficiency of the formed sodium-ion battery.

[0010] The patent document with the publication number CN117117187A (published on November 24, 2023) discloses a sodium-ion battery hard carbon negative electrode slurry and a preparation method thereof. The sodium-ion battery hard carbon negative electrode slurry includes the following raw materials: negative electrode active material hard carbon, conductive agent, and binder. The binder is a mixture of sodiumized propylene acid homopolymer and sodium carboxymethyl cellulose (CMC). The preparation method includes the following steps:

[0011] (1) CMC and deionized water are stirred and dispersed to form a glue solution; (2) conductive agent is added to the glue solution and stirred and dispersed to form conductive glue; (3) negative hard carbon material is added to the conductive glue and stirred and dispersed to obtain a mixed slurry; (4) sodiumized propylene acid homopolymer is added to the mixed slurry and stirred and dispersed to obtain a sodium-ion battery hard carbon negative electrode slurry.

[0012] The CMC used in the invention has good solubility and dispersibility in water, but when it is mixed with negative hard carbon material, the surface properties of the hard carbon material and the polar properties of the CMC are not very compatible, which can lead to poor dispersion uniformity of the two, thereby affecting the cycle stability of the finally prepared sodium-ion battery hard carbon negative electrode slurry.

[0013] Therefore, although hard carbon is considered as a very promising negative electrode material for sodium-ion batteries, its low first-cycle coulombic efficiency, unstable cycle performance, and poor rate performance reduce the electrical performance of sodium-ion batteries, so there is a need to develop a new hard carbon material. SUMMARY

[0014] To solve the above problems, the purpose of the present invention is to provide a preparation method of sodium-based modified phenolic resin hard carbon negative electrode. The sodium-based modified phenolic resin is synthesized by amino phenolic resin, and the pores are formed between the cross-linked phenolic resin matrix by the steam generated by the sodium-based modified phenolic resin, generating a suitable closed porous structure, improving the sodium storage performance of the hard carbon negative electrode, thereby improving the first-cycle coulombic efficiency and cycle stability of the hard carbon negative electrode.

[0015] To achieve the above-mentioned purposes, the technical solutions provided by the present invention are as follows:

[0016] In a first aspect, the present invention provides a preparation method of sodium-based modified phenolic resin, including the following steps:

[0017] (1) Under the action of an alkaline catalyst, a phenolic compound is dissolved in a solvent and undergoes a condensation reaction with an aldehyde compound to obtain an amino phenolic resin;

[0018] (2) A neutralization reaction occurs between 5-amino-1,2,3-benzene tricarboxylic acid and a sodium hydroxide solution;

[0019] (3) adding organic solvent, amino phenolic resin, triethylamine and epoxy propylene aldehyde diethylol into the container for neutralization reaction to generate addition reaction, and obtaining sodium-based modified phenolic resin.

[0020] As a further preferred embodiment of the present application, in step (2), the phenolic compound is 40-60 parts by mass, 5-amino-1,2,3-benzene tricarboxylic acid is 3-7 parts by mass, sodium hydroxide solution is 10-20 parts by mass, amino phenolic resin is 100-160 parts by mass, triethylamine is 2-5 parts by mass, and epoxy propylene aldehyde diethylol is 28-56 parts by mass.

[0021] As a further preferred embodiment of the present application, the solvent is ethanol aqueous solution.

[0022] The mass percentage of the sodium hydroxide solution is 10wt%-30wt%.

[0023] The organic solvent is tetrahydrofuran.

[0024] As a further preferred embodiment of the present application, the temperature of the condensation reaction is 20-25℃, the reaction time is 120-180min, and the reaction is dried at 105-115℃ after the reaction is completed.

[0025] The temperature of the neutralization reaction is 20-25℃, and the reaction time is 50-120min.

[0026] The temperature of the addition reaction is 60-80℃, and the reaction time is 50-120min.

[0027] As a further preferred embodiment of the present application, the phenolic compound includes one or any combination of 2-amino phenol, 3-amino phenol, 4-amino phenol, resorcinol, phloroglucinol, cresol, mixed cresol, nonyl phenol, octyl phenol, cardanol, aralkyl phenol, and bisphenol A.

[0028] The basic catalyst includes one or any combination of sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide, sodium carbonate, potassium carbonate, sodium methoxide, sodium ethoxide, sodium isopropyl alcohol, ammonia, magnesium oxide, ethylenediamine, tertiary amine, and triethylamine.

[0029] The aldehyde compound includes one or any combination of formaldehyde, paraformaldehyde, furfural, and acetaldehyde.

[0030] In a second aspect, the present application further provides a sodium-based modified phenolic resin prepared according to the preparation method of the sodium-based modified phenolic resin of the first aspect.

[0031] In a third aspect, the present application further provides a preparation method of sodium-based modified phenolic resin hard carbon negative electrode, using the sodium-based modified phenolic resin of the second aspect, including the following steps:

[0032] The sodium-based modified phenolic resin is carbonized under an inert atmosphere and ground, and the active material is obtained by sieving;

[0033] The active material, the conductive agent and the binder are mixed uniformly and coated on a copper foil, and then dried and rolled to obtain the sodium ion battery negative electrode sheet.

[0034] As a further preferred embodiment of the present application, the inert atmosphere is argon;

[0035] The carbonization temperature is 1200-1400℃, and the carbonization time is 3-5h;

[0036] The grinding speed is 300-800r / min, and the grinding time is 5-10h;

[0037] The sieving is performed with 200-600 mesh.

[0038] As a further preferred embodiment of the present application, the weight ratio of the active material, the conductive agent and the binder is (70-80) : 10 : (20-10);

[0039] The coating thickness is 120-160μm;

[0040] The conductive agent includes one or more of carbon black, acetylene black, vapor-deposited carbon fiber, conductive graphite, carbon nanotube, graphene and nitrogen-doped carbon;

[0041] The binder includes one or more of sodium alginate, sodium polyacrylate and sodium carboxymethyl cellulose.

[0042] In a fourth aspect, the present application further provides a sodium-based modified phenolic resin hard carbon negative electrode, which is prepared according to the preparation method of the sodium-based modified phenolic resin hard carbon negative electrode of the third aspect.

[0043] The present application has the following advantages:

[0044] (1) The present application uses resin material as the negative electrode material of the sodium ion battery. Since the resin material generally has a stable crystal structure and has higher structural stability, the sodium ion battery formed thereby has higher ion transmission efficiency and charging and discharging speed, and can significantly improve the initial coulomb efficiency of the sodium ion battery and enhance the stability of the cycle performance.

[0045] (2) It has been found that the sodium-based modified phenolic resin can generate steam, thereby forming pores between the crosslinked phenolic resin matrix and generating a suitable closed porous structure, which is conducive to the preparation of a high-capacity hard carbon negative electrode, improves the initial coulomb efficiency and rate performance of the sodium ion battery, and the optimal hard carbon negative electrode obtained by the method of the present application exhibits a high sodium storage capacity of about 410mAh / g while maintaining a high initial coulomb efficiency. DETAILED DESCRIPTION

[0046] In view of the deficiencies in the prior art, the present inventors have long studied and practiced to propose the technical solution of the present application, which will be further explained below in terms of the technical solution, its implementation process and principles, etc. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the protection scope of the present application.

[0047] Example 1

[0048] Example 1 provides a preparation method of a sodium-based modified phenolic resin hard carbon negative electrode, comprising the following steps:

[0049] Step 1: Dissolve 40 grams of 2-aminophenol and 40 ml of 25wt% sodium hydroxide solution into 2500 ml of 33vol% ethanol aqueous solution to form a base solution; inject 140 ml of 37wt% formaldehyde into the base solution under mechanical stirring at room temperature, and then further react for 120 min; after centrifugal washing, dry at 105℃ overnight to obtain an amino phenolic resin.

[0050] Step 2: Add 3 grams of 5-amino-1,2,3-benzene tricarboxylic acid, 10 grams of 10wt% sodium hydroxide solution, and 500 grams of tetrahydrofuran, 2 grams of triethylamine, and 28 grams of epoxy propylene aldehyde diethylol into a reaction kettle, and stir for 50 min at room temperature; then add 100 grams of amino phenolic resin, and stir for 50 min at 60℃; after the reaction is completed, remove the tetrahydrofuran by distillation to obtain a sodium-based modified phenolic resin.

[0051] Step 3: Carbonize 10 grams of the sodium-based modified phenolic resin in a tube furnace under an argon atmosphere at a carbonization temperature of 1200℃ for 3h, and then mill in a ball mill at 300r / min for 5h, and then sieve through a 200 mesh sieve to obtain an active material.

[0052] Step 4: Mix the active material, conductive agent (carbon black), and binder (sodium alginate) in a weight ratio of 70:10:20 in N-methyl pyrrolidone as a solvent, and then coat on a copper foil with a thickness of 120μm; vacuum dry at 60℃ for 10h, and then roll to a thickness of 75μm to obtain a sodium ion battery negative electrode sheet.

[0053] Example 2

[0054] Example 2 provides a preparation method of a sodium-based modified phenolic resin hard carbon negative electrode, comprising the following steps:

[0055] Step 1: 50 grams of 3-aminophenol and 50 ml of 25 wt% ammonium hydroxide solution were dissolved in 3000 ml of 33 vol% ethanol aqueous solution to form a base solution; 160 ml of 37 wt% acetaldehyde solution was injected into the base solution under mechanical stirring at room temperature, and then further reacted for 160 min, washed by centrifugation, and dried at 110°C overnight to obtain an amino phenolic resin;

[0056] Step 2: 5 grams of 5-amino-1,2,3-benzene tricarboxylic acid, 15 grams of 20 wt% sodium hydroxide solution, were added to a reaction kettle, stirred at room temperature for 85 min, then 130 grams of amino phenolic resin, 750 grams of tetrahydrofuran, 3.5 grams of triethylamine, 42 grams of epoxy propylene glycol, were added, and stirred at 70°C for 85 min, after the reaction was completed, the tetrahydrofuran was removed by distillation, and a sodium-based modified phenolic resin was obtained;

[0057] Step 3: 15 grams of sodium-based modified phenolic resin were carbonized at 1300°C for 4 hours under argon atmosphere in a tube furnace, then ball milled at 600 / min for 8 hours in a ball mill, and then sieved through a 400 mesh sieve to obtain an active material.

[0058] Step 4: The active material, conductive agent (acetylene black), and binder (sodium polyacrylate) were mixed uniformly in a weight ratio of 75:10:15 using N-methyl pyrrolidone as the solvent, then coated on a copper foil with a thickness of 140 μm, vacuum dried at 70°C for 15 hours, then rolled to a thickness of 110 μm, and a sodium ion battery negative electrode sheet was obtained.

[0059] Example 3

[0060] Example 3 provides a method for preparing a sodium-based modified phenolic resin hard carbon negative electrode, comprising the following steps:

[0061] Step 1: 60 grams of 4-aminophenol and 60 ml of 25 wt% potassium hydroxide solution were dissolved in 3500 ml of 33 vol% ethanol aqueous solution to form a base solution; 180 ml of 37 wt% furfural solution was injected into the base solution under mechanical stirring at room temperature, then further reacted for 180 min, washed by centrifugation, and dried at 115°C overnight to obtain an amino phenolic resin;

[0062] Step 2: 7 grams of 5-amino-1,2,3-benzene tricarboxylic acid, 20 grams of 30 wt% sodium hydroxide solution, were added to a reaction kettle, stirred at room temperature for 120 min, then 160 grams of amino phenolic resin, 1000 grams of tetrahydrofuran, 5 grams of triethylamine, 56 grams of epoxy propylene glycol, were added, and stirred at 80°C for 120 min, after the reaction was completed, the tetrahydrofuran was removed by distillation, and a sodium-based modified phenolic resin was obtained;

[0063] Step 3: 20 grams of sodium-modified phenol-formaldehyde resin was carbonized at 1400℃ for 5h under argon atmosphere in a tube furnace, then ball-milled at 800r / min for 10h in a ball mill, and finally sieved through a 600-mesh sieve to obtain the active material.

[0064] Step 4: The active material, conductive agent (carbon nanotube), and binder (sodium carboxymethyl cellulose) were mixed uniformly in a weight ratio of 80:10:10 using N-methyl pyrrolidone as the solvent, and then coated on a copper foil with a thickness of 160μm. The coated copper foil was vacuum dried at 80℃ for 20h, and then roll-pressed to a thickness of 150μm to obtain a negative electrode sheet for sodium-ion batteries.

[0065] Comparative Example 1

[0066] In Comparative Example 1, Step 2 was deleted, i.e., the step of synthesizing sodium-modified phenol-formaldehyde resin was omitted, and the remaining technical solutions were the same as those in Example 1. The details are as follows:

[0067] Step 1: 40 grams of 2-aminophenol and 40ml of a 25wt% sodium hydroxide solution were dissolved in a 2500ml ethanol aqueous solution with a volume concentration of 33vol% to form a base solution; 140ml of a 37wt% formaldehyde solution was injected into the base solution under mechanical stirring at room temperature, and then further reacted for 120min. After centrifugal washing and drying at 105℃ overnight, an aminophenol-formaldehyde resin was obtained.

[0068] Step 2: 10 grams of the aminophenol-formaldehyde resin was carbonized at 1200℃ for 3h under argon atmosphere in a tube furnace, then ball-milled at 300r / min for 5h in a ball mill, and finally sieved through a 200-mesh sieve to obtain the active material.

[0069] Step 3: The active material, carbon black, and sodium alginate were mixed uniformly in a weight ratio of 70:10:20 using N-methyl pyrrolidone as the solvent, and then coated on a copper foil with a thickness of 120μm. The coated copper foil was vacuum dried at 60℃ for 10h, and then roll-pressed to a thickness of 75μm to obtain a negative electrode sheet for sodium-ion batteries.

[0070] Comparative Example 2

[0071] In Comparative Example 2, 5-amino-1,2,3-benzene tricarboxylic acid was not added in Step 2, and the remaining technical solutions were the same as those in Example 1.

[0072] Comparative Example 3

[0073] In Comparative Example 3, epoxy propylene aldehyde diethyl acetal was not added in Step 2, and the remaining technical solutions were the same as those in Example 1.

[0074] Test Example 1

[0075] The electrochemical performance of the above examples and comparative examples is tested as follows:

[0076] The method of assembling the batteries of the hard carbon negative electrode materials prepared in each of examples 1-3 and each of comparative examples 1-3 is as follows: the batteries are assembled in a high-purity argon atmosphere glove box, in the order of positive electrode shell-electrode piece-electrolyte-separator-electrolyte-sodium piece-negative electrode shell, wherein a CR2032 button cell shell is used, the electrolyte is: 1.0M NaPF6-containing EC: DMC = 1:1 (volume ratio) electrolyte, and the separator is a glass fiber separator.

[0077] The constant current charge / discharge test is performed on a battery test system, the voltage range is 0.01 to 3V, and the cycle current density is 1C. The test results are shown in Table 1.

[0078] Table 1: Constant current charge / discharge test results

[0079]

[0080] As can be seen from the test results in Table 1, the sodium-based modified phenolic resin hard carbon material prepared by the present application has excellent electrochemical performance, significantly improves the capacity, and improves the coulombic efficiency and cycle stability, thereby providing a thought and possibility for the industrial application of sodium ion batteries.

[0081] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the implementation process of the present application has been described in detail above, those skilled in the art can still modify the technical solutions recorded in the above examples, or replace some of the technical features with equivalent ones. Any modification, equivalent replacement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for producing a sodium-modified phenol-aldehyde resin, characterized by, It comprises the following steps: (1) under the action of alkaline catalyst, phenolic compound is dissolved in solvent and condensed with aldehyde compound to obtain amino phenolic aldehyde resin; (2) neutralization reaction of 5-amino-1,2,3-benzene tricarboxylic acid and sodium hydroxide solution; (3) addition reaction of organic solvent, amino phenolic aldehyde resin, triethylamine and epoxy propylene aldehyde diethyl glycol in the container for neutralization reaction to obtain sodium modified phenolic aldehyde resin; According to mass fraction, 5-amino-1,2,3-benzene tricarboxylic acid 3-7 parts, sodium hydroxide solution 10-20 parts, amino phenolic aldehyde resin 100-160 parts, triethylamine 2-5 parts, epoxy propylene aldehyde diethyl glycol 28-56 parts; The mass percentage of the sodium hydroxide solution is 10wt%-30wt%.

2. The preparation method of the sodium modified phenolic aldehyde resin according to claim 1, characterized in that, The solvent is ethanol aqueous solution; The organic solvent is tetrahydrofuran.

3. The preparation method of the sodium modified phenolic aldehyde resin according to claim 1, characterized in that, The temperature of the condensation reaction is 20-25℃, the reaction time is 120-180min, and after the reaction is completed, drying is carried out at 105-115℃; The temperature of the neutralization reaction is 20-25℃, the reaction time is 50-120min; The temperature of the addition reaction is 60-80℃, and the reaction time is 50-120min.

4. The method of producing a sodium-modified phenol-aldehyde resin according to claim 1, characterized by, The phenolic compound includes one or any of 2-amino phenol, 3-amino phenol, 4-amino phenol, m-dihydroxybenzene, phloroglucinol, cresol, nonyl phenol, octyl phenol, cardanol, aralkyl phenol and bisphenol A; The alkaline catalyst includes one or any of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, sodium methoxide, sodium ethoxide, sodium isopropyl alcohol, ammonia, magnesium oxide, ethylenediamine and tertiary amine; The aldehyde compound includes one or any of formaldehyde, polyformaldehyde, furfural and acetaldehyde.

5. The sodium modified phenolic aldehyde resin prepared by the preparation method of any one of claims 1-4.

6. A method for preparing a sodium-based modified phenol-formaldehyde resin hard carbon negative electrode, characterized by, The use of the sodium modified phenolic aldehyde resin of claim 5 comprises the following steps: The sodium modified phenolic aldehyde resin is carbonized and ground under inert atmosphere, and sieved to obtain active material; the carbonization temperature is 1200-1400℃, and the carbonization time is 3-5h; The active material, conductive agent and binder are mixed uniformly and coated on copper foil, dried and rolled to obtain sodium ion battery negative electrode sheet.

7. The preparation method of the sodium modified phenolic aldehyde resin hard carbon negative electrode according to claim 6, characterized in that, The content of the sodium modified phenolic aldehyde resin is 10-20g; The inert atmosphere uses argon; The grinding speed is 300-800r / min, and the grinding time is 5-10h; The sieving uses 200-600 mesh.

8. The method of producing a sodium-modified phenol-aldehyde resin hard carbon negative electrode according to claim 6, characterized by, The weight ratio of the active material, conductive agent and binder is (70-80) : 10 : (20-10); The coating thickness is 120-160μm; The conductive agent includes one or more of carbon black, vapor deposition carbon fiber, conductive graphite, carbon nanotube, graphene and nitrogen-doped carbon. The binder includes one or more of sodium alginate, sodium polyacrylate, and sodium carboxymethyl cellulose.

9. The sodium-modified phenolic resin hard carbon negative electrode prepared by the preparation method of any one of claims 6-8.

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