Preparation method and application of hard carbon negative electrode material rich in sodium ion battery carbonyl

Abstract

The application belongs to the technical field of sodium ion battery negative electrode materials, and particularly relates to a preparation method and application of a sodium ion battery hard carbon negative electrode material rich in carbonyl groups, which comprises the following steps: (1) taking a carbon source, a catalyst and an acylation reagent, dissolving and mixing them in an organic solvent; (2) performing an acylation reaction on the mixture obtained in step (1) by programming the temperature to a certain temperature, and then evaporating the solvent; (3) deeply oxidizing the acylation product obtained in step (2) in an oxygen-containing atmosphere to obtain a hard carbon precursor rich in carbonyl groups; and (4) taking the hard carbon precursor obtained in step (3), carbonizing it at high temperature in an inert gas environment, and then naturally cooling to obtain the target product, i.e., the sodium ion battery hard carbon negative electrode material. The carbon material has ideal disorder degree, high yield, rich closed pores, high platform capacity of the sodium ion battery, good cycle stability and rate performance, and strong sodium storage capacity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sodium ion battery negative electrode materials, and particularly relates to a preparation method of a sodium ion battery hard carbon negative electrode material rich in carbonyl groups and application thereof. BACKGROUND

[0002] Thanks to the advantages of high abundance, low cost, excellent charge-discharge characteristics and the like of sodium resources, sodium ion batteries are considered to be one of the most potential large-scale energy storage technologies. The negative electrode material of the battery greatly affects the energy density of the battery, and the traditional graphite is limited in further application in sodium ion batteries due to too small interlayer spacing and inability to form a thermally stable intercalation compound with graphite. The complex molecular structure of hard carbon has more disordered structures, higher defect concentration, higher content of heteroatoms, larger graphite interlayer spacing, and more closed pore structures, and the above advantages create various types of sodium storage active sites. Based on this, developing a negative electrode material with low cost, high theoretical specific capacity and good stability is the key to realizing the wide application of sodium ion batteries.

[0003] As a traditional hard carbon precursor, phenolic resin is relatively expensive, and the biomass-based hard carbon precursor has problems such as low carbon yield and complex structure difficult to accurately control. Therefore, finding a low-cost and high-yield hard carbon precursor has become the key to solving the bottleneck of the development of the sodium ion battery industry. Petroleum-based pitch has the advantages of high aromaticity, high carbon content, low price and the like, and is a potential hard carbon raw material, but due to its high-temperature graphitization, small interlayer spacing, and inability to realize the intercalation of sodium ions, the specific capacity is low and cannot meet the commercialization needs of sodium ion batteries. In view of this, the petroleum-based pitch is reasonably modified and designed to introduce a large number of carbonyl groups, form short-range ordered graphite crystallites, and form closed pores, which can effectively improve the sodium storage capacity of the hard carbon material. SUMMARY

[0004] The present application aims to overcome the deficiencies of the prior art and provide a preparation method of a sodium ion battery hard carbon negative electrode material rich in carbonyl groups, which has ideal disorder degree of carbon material, high yield, rich closed pores, high platform capacity of sodium ion battery, good cycle stability and rate performance, and strong sodium storage capacity.

[0005] The present application also provides an application of a product obtained by the preparation method of the sodium ion battery hard carbon negative electrode material rich in carbonyl groups in the field of sodium ion secondary batteries.

[0006] To solve the above technical problems, the present application is implemented as follows:

[0007] A preparation method of a sodium ion battery hard carbon negative electrode material rich in carbonyl groups, comprising the following steps:

[0008] (1) Taking a carbon source, a catalyst and an acylation reagent, dissolving and mixing them in an organic solvent;

[0009] (2) The mixture obtained in step (1) is programmed to a certain temperature, and after acylation reaction, the solvent is evaporated;

[0010] (3) The acylated product obtained in step (2) is deeply oxidized in an oxygen-containing atmosphere to obtain a hard carbon precursor rich in carbonyl groups;

[0011] (4) The hard carbon precursor obtained in step (3) is carbonized at high temperature in an inert gas environment, and then naturally cooled to obtain the sodium ion battery hard carbon negative material.

[0012] Further, in step (1), the carbon source is petroleum-based pitch; the catalyst is an organic acid, an organic base, a proton acid or a Lewis acid; the acylation reagent is acetyl chloride, acetic anhydride, benzoyl chloride or terephthaloyl chloride; and the organic solvent is chloroform, dichloromethane, tetrahydrofuran or petroleum ether.

[0013] Further, the catalyst is an organic acid p-toluenesulfonic acid, an organic base triethylamine, a proton acid sulfuric acid or a Lewis acid aluminum chloride.

[0014] Further, the petroleum-based pitch is ethylene tar or viscosity-reducing residual oil.

[0015] Further, in step (1), the amount of catalyst added is 1-15% of the total mass of raw materials.

[0016] Further, the amount of acylation reagent added is 5-30% of the total mass of raw materials.

[0017] Further, in step (2), the acylation reaction temperature is 80-180℃, and the reaction time is 3-24h; in step (3), the deep oxidation temperature is 200-400℃, and the oxidation time is 1-10h.

[0018] Further, in step (4), the high-temperature carbonization temperature is 700-1600℃, and the carbonization time is 1-6h.

[0019] Further, the first charge capacity of the sodium ion battery hard carbon negative material is 320mAhg -1 , the platform capacity is 183mAhg -1 , and the capacity remains at 92.4% after 100 cycles.

[0020] The product obtained by the above method for preparing sodium ion battery hard carbon negative material rich in carbonyl groups is applied in the field of sodium ion secondary batteries.

[0021] The present application adopts low-cost petroleum-based pitch as a carbon source, introduces carbonyl groups into the carbon source through acylation reaction, and performs deep oxidation under an oxygen-containing atmosphere to obtain a hard carbon precursor with a large number of oxygen-containing functional groups (mainly carbonyl groups), and the hard carbon negative electrode material is prepared by high-temperature carbonization treatment. When the hard carbon material rich in carbonyl groups is applied to a sodium ion secondary battery, the disorder degree of the carbon material is significantly improved, a large number of closed pores are formed, the platform capacity of the sodium ion battery can be effectively improved, and the sodium storage capacity of the hard carbon material is improved. It is expected to promote the application of sodium ion batteries in electric vehicles, industrial energy storage systems and other fields.

[0022] Petroleum-based pitch is used as a raw material, carbonyl groups are introduced through acylation reaction, and then deep oxidation is performed in an oxygen-containing atmosphere to form a hard carbon precursor rich in a large number of oxygen-containing functional groups, and a hard carbon negative electrode material for sodium ion batteries is obtained after high-temperature carbonization. The obtained pitch-based hard carbon material has a high low-voltage platform (<0.1V) capacity, good cycle stability and rate performance, which is conducive to promoting and realizing the commercial application of petroleum-based pitch hard carbon material in sodium ion batteries.

[0023] Compared with the prior art, the present application has the following advantages: ethylene tar and viscosity-reducing residual oil are low in price, the acylation reaction conditions are mild, and the process is simple, the oxygen content after acylation reaction reaches 11%, and the oxygen content after deep oxidation reaches 26%, effectively preventing the graphitization process of petroleum-based pitch. The prepared hard carbon material has high yield, high specific capacity and good cycle stability, and can fully meet the demand of sodium ion battery hard carbon negative electrode material. The structure of the hard carbon is designed at the molecular level, which provides strong support for the future development of sodium ion battery hard carbon negative electrode material. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The XRD spectrum of the hard carbon of Example 1 of the present application.

[0025] Figure 2 The cycle stability diagram of Example 2 of the present application.

[0026] Figure 3 The charge-discharge curve of Example 3 of the present application.

[0027] Figure 4 The scanning electron microscope image of Example 4 of the present application. DETAILED DESCRIPTION

[0028] In order to make the technical personnel in the art better understand the technical solutions of the present application, the present application will be further described below in conjunction with specific examples. Obviously, the described examples are only a part of the embodiments of the present application, rather than all the embodiments. These examples should be understood as merely illustrating the present application, but not limiting the protection scope of the present application. After reading the content described in the present application, based on the technical solutions and examples of the present application, all other examples obtained by various modifications or modifications of the present application also fall within the protection scope of the present application. In the following examples, the experimental methods are conventional methods, unless otherwise specified.

[0029] Example 1

[0030] The preparation method of the hard carbon negative material rich in carbonyl for sodium ion battery comprises the following steps:

[0031] (1) ethylene tar is used as raw material; triethylamine is used as catalyst, and the addition amount is 5% of the total mass of the raw material; acetyl chloride is used as acylation reagent, and the addition amount is 20% of the total mass of the raw material; the above materials are dissolved in chloroform and mixed and stirred until completely dissolved.

[0032] (2) the mixture obtained in step (1) is heated to 100℃ under reflux, and acylation reaction is carried out for 6h to obtain acylation product.

[0033] (3) the acylation product obtained in step (2) is heated to 260℃ at a heating rate of 2℃ / min under oxygen atmosphere, and oxidized for 2h to obtain hard carbon precursor containing a large number of carbonyl groups.

[0034] (4) the hard carbon precursor obtained in step (3) is carbonized at a high temperature of 1300℃ under nitrogen atmosphere at a heating rate of 2℃ / min for 2h to obtain the final hard carbon negative material.

[0035] Sodium ion assembly and performance test:

[0036] The hard carbon negative material, conductive agent (acetylene black) and binder (PVDF) are mixed in a mass ratio of 8:1:1 and dissolved in N-methyl pyrrolidone, the slurry is uniformly coated on a copper foil, and the copper foil is taken out after vacuum drying at 80℃ for 12h and punching. In a glove box protected by high-purity argon, a metal sodium sheet is used as a counter electrode, glass fiber is used as a separator, NaClO4 (EC:DEC=1:1) is used as an electrolyte, and a LIR2032 type button cell is assembled. The electrochemical sodium storage performance test is carried out at room temperature, and the voltage range is 0-3V, and the platform region (0-0.1V).

[0037] Example 2

[0038] The preparation method of the hard carbon negative material rich in carbonyl for sodium ion battery comprises the following steps:

[0039] (1) ethylene tar as raw material; aluminum chloride as catalyst, the addition amount is 10% of the total mass of raw material, benzoyl chloride as acylation reagent, the addition amount is 30% of the total mass of raw material, the above materials are dissolved in dichloromethane, mixed and stirred until completely dissolved.

[0040] (2) the mixture obtained in step (1) is heated to 80℃ under reflux, and acylation reaction is carried out for 10h to obtain acylation product.

[0041] (3) the acylation product obtained in step (2) is heated to 300℃ at a heating rate of 3℃ / min under oxygen atmosphere, and oxidized for 4h to obtain hard carbon precursor containing a large number of carbonyl groups.

[0042] (4) the hard carbon precursor obtained in step (3) is carbonized at a high temperature of 1400℃ under nitrogen atmosphere at a heating rate of 2℃ / min for 1h to obtain the final hard carbon negative electrode material.

[0043] Sodium ion assembly and performance test are the same as example 1.

[0044] Example 3

[0045] The preparation method of the sodium ion battery hard carbon negative electrode material rich in carbonyl groups comprises the following steps:

[0046] (1) take the reduced viscosity residual oil as raw material; take sulfuric acid as catalyst, the addition amount is 8% of the total mass of raw material, terephthaloyl chloride as acylation reagent, the addition amount is 20% of the total mass of raw material, the above materials are dissolved in petroleum ether, mixed and stirred until completely dissolved.

[0047] (2) the mixture obtained in step (1) is heated to 120℃ under reflux, and acylation reaction is carried out for 16h to obtain acylation product.

[0048] (3) the acylation product obtained in step (2) is heated to 325℃ at a heating rate of 3℃ / min under oxygen atmosphere, and oxidized for 3h to obtain hard carbon precursor containing a large number of carbonyl groups.

[0049] (4) the hard carbon precursor obtained in step (3) is carbonized at a high temperature of 1300℃ under nitrogen atmosphere at a heating rate of 2℃ / min for 3h to obtain the final hard carbon negative electrode material.

[0050] Sodium ion assembly and performance test are the same as example 1.

[0051] Example 4

[0052] The preparation method of the sodium ion battery hard carbon negative electrode material rich in carbonyl groups comprises the following steps:

[0053] (1) Take the reduced viscosity residual oil as raw material; p-toluene sulfonic acid as catalyst, the addition amount is 12% of the total mass of raw material, acetic anhydride as acylation reagent, the addition amount is 15% of the total mass of raw material, dissolve the above materials in tetrahydrofuran, mix and stir until completely dissolved.

[0054] (2) Heat the mixture obtained in step (1) to reflux at 140℃, acylate for 20h to obtain acylated product.

[0055] (3) The acylated product obtained in step (2) is heated to 380℃ at a heating rate of 3℃ / min under oxygen atmosphere, and oxidized for 6h to obtain hard carbon precursor containing a large number of carbonyl groups.

[0056] (4) The hard carbon precursor obtained in step (3) is carbonized at a high temperature of 1000℃ under nitrogen atmosphere at a heating rate of 2℃ / min for 4h to obtain the final hard carbon negative electrode material.

[0057] Sodium ion assembly and performance test are the same as example 1.

[0058] Experimental part:

[0059] The hard carbon negative electrode materials prepared in examples 1, 2, 3 and 4 are respectively subjected to element analysis and charge-discharge performance test. The specific results are shown in the following table

[0060] Table 1 Element analysis and charge-discharge performance index of hard carbon negative electrode material

[0061]

[0062] The above described examples are only preferred embodiments of the present application and are not intended to limit the present application. It should be noted that the present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, 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 preparing a carbonyl-rich hard carbon anode material for sodium-ion batteries, characterized in that, Includes the following steps: (1) Take a carbon source, catalyst and acylation reagent, dissolve and mix them in an organic solvent; the carbon source is petroleum-based pitch; the acylation reagent is acetyl chloride, acetic anhydride, benzoyl chloride or terephthaloyl chloride; the organic solvent is chloroform, dichloromethane, tetrahydrofuran or petroleum ether; the catalyst is an organic acid p-toluenesulfonic acid, an organic base triethylamine, a protic acid sulfuric acid or a Lewis acid aluminum chloride; the petroleum-based pitch is ethylene tar or viscosity-reducing residue oil; the amount of catalyst added is 1-15% of the total mass of the raw materials; the amount of acylation reagent added is 5-30% of the total mass of the raw materials; (2) The mixture obtained in step (1) is heated to a certain temperature to carry out the acylation reaction and then the solvent is evaporated; the acylation reaction temperature is 80-180℃ and the reaction time is 3-24h. (3) The acylated product obtained in step (2) is deeply oxidized in an oxygen-containing atmosphere to obtain a hard carbon precursor rich in carbonyl groups; the deep oxidation temperature is 200-400℃ and the oxidation time is 1-10h. (4) Take the hard carbon precursor obtained in step (3), carbonize it at high temperature in an inert gas environment, and then cool it naturally to obtain the target product, sodium-ion battery hard carbon anode material; the high temperature carbonization temperature is 700℃~1600℃, and the carbonization time is 1~6h.

2. The application of the product obtained by the preparation method of the carbonyl-rich sodium-ion battery hard carbon anode material as described in claim 1 in the field of sodium-ion secondary batteries.

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