CN117125693A - Preparation method of hard carbon material, anode and sodium ion battery - Google Patents

Abstract

The embodiment of the application provides a preparation method of a hard carbon material, a negative electrode and a sodium ion battery, wherein the method comprises the following steps: the mulberry branch is used as a precursor to prepare the mulberry branch derived hard carbon material. In the embodiment of the application, the hard carbon material has wide raw material sources, is cheap and easy to obtain, has simple preparation process and is environment-friendly, and the preparation method can be suitable for large-scale production. In addition, the hard carbon material prepared by taking the mulberry branches as precursors contains rich nitrogen and phosphorus elements, improves the conductivity of the material, provides rich active sites for sodium ion storage, has excellent multiplying power performance and cycle stability as a negative electrode of a sodium ion battery, and has wide application prospect.

Description

Preparation method of hard carbon material, negative electrode material, negative electrode and sodium ion battery

Technical field

This application relates to the technical field of sodium-ion batteries, specifically to a preparation method of hard carbon materials, negative electrode materials, negative electrodes and sodium-ion batteries.

Background technique

Lithium-ion batteries have been widely used in portable electronic products, power vehicles, large-scale energy storage and other fields. With the development of the industry, the demand for lithium has increased; however, the lack of lithium resources and uneven distribution have resulted in excessively high lithium ore prices. , which seriously limits its development and cannot meet the increasing development of energy storage batteries.

Compared with lithium-ion batteries, sodium-ion batteries have the advantages of large sodium reserves and low cost. They are the most promising alternative technology in many systems and have become a strong candidate in the field of large-scale energy storage. Sodium-ion batteries have similar working principles to lithium-ion batteries and are less difficult to develop. At present, cathode materials with excellent performance have been successfully developed following the example of lithium-ion cathode materials. However, traditional anode materials graphite and silicon carbon have been found to be difficult to store sodium and cannot be used as Used as anode material for sodium-ion batteries. Hard carbon materials have a highly disordered structure and rich microporous structure, which provide a large number of active sites for sodium ions; at the same time, the large interlayer spacing is also conducive to the transmission of sodium ions.

At present, a large number of researchers choose expensive resin-based materials as precursors, which is not conducive to commercial development. Biomass is used as a precursor with wide sources and low prices. However, the current material processing methods are cumbersome and the consistency of the product is difficult to guarantee, which increases the difficulty and cost of large-scale production. At the same time, the rate performance and cycle performance are poor, so it is urgent to develop Low-cost, efficient and convenient hard carbon materials with excellent electrochemical properties and efficient preparation processes.

Contents of the invention

In view of this, this application provides a preparation method of hard carbon materials, negative electrode materials, negative electrodes and sodium-ion batteries, so as to help solve the problems existing in the negative electrode materials of sodium-ion batteries in the prior art.

In a first aspect, embodiments of the present application provide a method for preparing hard carbon materials, including:

Mulberry branch-derived hard carbon materials were prepared using mulberry branches as precursors.

In a possible implementation, the preparation of mulberry branch-derived hard carbon materials using mulberry branches as precursors includes:

Under protective gas, the precursor powder is subjected to high-temperature carbonization treatment to obtain preliminary carbonized powder, and the precursor powder is mulberry branch powder;

The preliminary carbonized powder is added to the hydrochloric acid solution, heated and stirred, washed and dried to obtain a mulberry branch-derived hard carbon material.

In a possible implementation, before the obtained precursor powder is subjected to high-temperature carbonization treatment under a protective gas to obtain preliminary carbonized powder, and the precursor powder is mulberry branch powder, the method further includes:

The precursor powder is obtained by peeling and cutting the mulberry branches into sections, cleaning, drying and ball milling.

In a possible implementation, the drying temperature is 100-140°C, and the drying time is 12-24 hours.

In a possible implementation manner, the rotation speed of the ball mill is 400-480 r/min, and the ball milling time is 1-4 hours.

In a possible implementation, the protective gas is argon and/or nitrogen, and the flow rate of the protective gas is 40-60 mL/min.

In a possible implementation, the temperature of the high-temperature carbonization treatment is 1000-1400°C, the time is 2-5h, the heating rate is 3-5°C/min, and it naturally drops to room temperature.

In a second aspect, embodiments of the present application provide a sodium-ion battery negative electrode material, including:

The mulberry branch-derived hard carbon material prepared by the method described in any one of the first aspects.

In a third aspect, embodiments of the present application provide a sodium-ion battery negative electrode, including:

Carrier, the carrier is in sheet form;

A coating layer is uniformly coated on the carrier, and the coating layer includes a conductive agent, a binder and the sodium ion battery negative electrode material described in the second aspect.

In a fourth aspect, embodiments of the present application provide a sodium-ion battery, including the sodium-ion battery negative electrode described in the third aspect.

In the embodiments of the present application, the raw materials of hard carbon materials are widely sourced, cheap and easy to obtain, the preparation process is simple, environmentally friendly, and can be suitable for large-scale production. In addition, the hard carbon material prepared from mulberry branches as a precursor is rich in nitrogen and phosphorus elements, which improves the conductivity of the material and provides abundant active sites for sodium ion storage. As a negative electrode for sodium ion batteries, it has excellent rate performance and cycle stability, and broad application prospects.

Description of the drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting any creative effort.

Figure 1 is a schematic flow chart of a method for preparing hard carbon materials provided by an embodiment of the present application;

Figure 2 is an SEM pattern of the mulberry branch-derived hard carbon material prepared in the embodiment of the present application;

Figure 3 is the XPS pattern of the mulberry branch-derived hard carbon material prepared in the embodiment of the present application;

Figure 4 is a rate performance diagram of a mulberry branch-derived hard carbon material provided in the embodiment of the present application;

Figure 5 is a cycle performance diagram of a mulberry branch-derived hard carbon material provided in the embodiment of the present application.

Detailed ways

In order to better understand the technical solution of the present application, the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

It should be clear that the described embodiments are only some of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of this application.

The terminology used in the embodiments of the present application is only for the purpose of describing specific embodiments and is not intended to limit the present application. As used in the embodiments and the appended claims, the singular forms "a," "the" and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise.

It should be understood that the term "and/or" used in this article is only an association relationship describing related objects, indicating that there can be three relationships, for example, A and/or B, which can mean: A alone exists, and A and A exist simultaneously. B, there are three situations of B alone. In addition, the character "/" in this article generally indicates that the related objects are an "or" relationship.

As the precursor of hard carbon materials, mulberry branches, when carbonized, inherit the rod-like structure of the branches, which are initially used to transport water and nutrients through channels and pores, forming a transmission network that allows electrolytes to enter and in the resulting Hard carbon provides more pathways and storage locations for sodium ions; in addition, mulberry branches themselves contain flavonoids and alkaloids. After carbonization, it was also found that the material still contains abundant nitrogen and phosphorus elements. These two elements are commonly used dopants. Hard carbon materials can not only improve electronic conductivity, but also introduce defects, generate active sites, and increase capacity. As the negative electrode of sodium-ion batteries, they can exhibit excellent electrochemical performance. Therefore, the embodiments of the present application provide a method for preparing hard carbon materials, using mulberry branches as precursors to prepare mulberry branch-derived hard carbon materials, which will be described in detail below with reference to specific examples.

Refer to Figure 1, which is a schematic flow chart of a method for preparing a hard carbon material provided in an embodiment of the present application. As shown in Figure 1, it mainly includes the following steps.

Step S101: Peel and cut the mulberry branches into sections, then wash, dry, and ball mill to obtain precursor powder.

In a possible implementation, the drying temperature of mulberry branches is 100-140°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C, etc. Those skilled in the art can adjust the temperature within this range according to actual needs. Adaptive selection can be made within the range; the drying time of mulberry branches is 12-24h, for example, 12h, 16h, 20h, 24h, etc. Those skilled in the art can make adaptive selection within this range according to actual needs. It should be pointed out that too low drying temperature and too short drying time will increase the difficulty of ball milling.

In a possible implementation, the ball mill speed is 400-480r/min, for example, 400r/min, 410r/min, 420r/min, 430r/min, 440r/min, 460r/min, 470r/min, 480r/ min, etc., those skilled in the art can make adaptive selections within this range according to actual needs; the ball milling time is 1-4h, for example, 1h, 2h, 3h, 4h, etc., those skilled in the art can make adaptive selections within this range according to actual needs. Make adaptive selections. It should be pointed out that too low a rotational speed and too short a ball milling time will cause the precursor powder particles to be too large and uneven.

Of course, those skilled in the art can also select other process parameters according to actual needs, and the embodiments of the present application do not specifically limit this.

In addition, in some possible implementations, it is also possible to directly use mulberry branch powder to prepare mulberry branch-derived hard carbon materials, that is, step S101 is omitted. In other words, the entire hard carbon material preparation process only includes step S102 and step S103.

Step S102: Under protective gas, perform high-temperature carbonization treatment on the precursor powder to obtain preliminary carbonized powder. The precursor powder is mulberry branch powder.

In a possible implementation, argon and/or nitrogen need to be introduced as a protective gas during the carbonization process of the precursor, and the protective gas flow rate is 40-60mL/min, for example, 40mL/min, 50mL/min, 60mL/min etc. Those skilled in the art can make adaptive selections within this range according to actual needs.

In a possible implementation, the temperature of the high-temperature carbonization treatment is 1000-1400°C, for example, 1000°C, 1100°C, 1200°C, 1300°C, 1400°C, etc. Those skilled in the art can adjust the temperature within this range according to actual needs. Make adaptive selection; the time is 2-5h, for example, 2h, 3h, 4h, 5h, etc. Those skilled in the art can make adaptive selection within this range according to actual needs; the heating rate is 5°C/min; it will naturally drop to room temperature. It should be pointed out that insufficient carbonization temperature and/or carbonization time will lead to undesirable pore structure and poorly stacked C-C aromatic structure; too high carbonization temperature will make the layers of hard carbon materials too small, which is not conducive to the transmission of sodium ions. .

Step S103: Add the preliminary carbonized powder to the hydrochloric acid solution for heating and stirring, washing and drying to obtain a mulberry branch-derived hard carbon material.

In a possible implementation, the concentration of the hydrochloric acid solution is 2-4 mol/L, for example, 2 mol/L, 3 mol/L, 4 mol/L, etc. Those skilled in the art can make adaptive selections within this range according to actual needs. ; The temperature of the heating and stirring treatment is 40-60°C, for example, 40°C, 50°C, 60°C, etc. Those skilled in the art can make adaptive selections within this range according to actual needs; the time of the heating and stirring treatment is 12-24h , for example, 12h, 16h, 20h, 24h, etc. Those skilled in the art can make adaptive selections within this range according to actual needs. It should be pointed out that if the concentration of the hydrochloric acid solution is too low and/or the heating and stirring time is not enough, the content of inorganic elements in the hard carbon material will be too high, occupying the active sites for sodium storage, causing unnecessary reactions and reducing the storage of sodium. ability.

The microscopic morphology of the mulberry branch-derived hard carbon material prepared by the method provided in the embodiments of the present application exhibits a rod-like structure, and the morphology is well preserved after grinding. In addition, the method has low preparation cost, simple preparation process and easy control of conditions.

Corresponding to the above embodiments, embodiments of the present application also provide a sodium ion battery negative electrode material. The sodium ion battery negative electrode material includes a mulberry branch-derived hard carbon material prepared by the above method.

Corresponding to the above embodiments, embodiments of the present application also provide a sodium ion battery negative electrode, including a carrier, the carrier being in a sheet shape; and a coating layer uniformly coated on the carrier. The coating layer includes a conductive agent, a binder and the sodium ion battery negative electrode material described in the above embodiment. In specific implementation, the ratio of conductive agent, binder and sodium-ion battery negative electrode material can be 1:1:8. Of course, those skilled in the art can adjust the proportions of the conductive agent, the binder and the negative electrode material of the sodium ion battery according to actual needs, and the embodiments of the present application do not specifically limit this.

In a possible implementation, the carrier can be copper foil, carbon-coated copper foil or carbon paper. Of course, those skilled in the art can select other conductive sheets as carriers according to actual needs, and the embodiments of the present application do not specifically limit this.

In a possible implementation, the conductive agent is Super-P and the binder is PVDF (5% mass fraction solution). Of course, those skilled in the art can select other types of conductive agents and adhesives according to actual needs, and the embodiments of the present application do not specifically limit this.

Corresponding to the above embodiments, embodiments of the present application also provide a sodium ion battery, which includes the sodium ion battery negative electrode described in the above embodiments. The sodium-ion battery can achieve high-capacity charge and discharge, and has excellent rate performance and cycle performance.

For ease of understanding, the technical solution provided by this application is described in detail below with reference to specific embodiments.

Example 1:

Cut the mulberry branches into small sections and ultrasonically clean them with industrial ethanol for 30 minutes. Put the cleaned mulberry branches into the oven and dry them at 120°C for 12 hours. After drying, use a ball mill to grind them at 450r/min for 1 hour to obtain the precursor powder. Take 2g of the precursor and heat it to 1200°C at a heating rate of 5°C/min in a tube furnace filled with nitrogen. Keep it for 2 hours. Take it out after natural cooling. Soak the carbonized product in 2mol/L hydrochloric acid solution. Heating and stirring at 60°C for 12 hours, then rinsing with deionized water until neutral, and drying to obtain hard carbon material.

Refer to Figure 2, which is an SEM pattern of the mulberry branch-derived hard carbon material prepared in the embodiment of the present application. Refer to Figure 3, which is an XPS pattern of the mulberry branch-derived hard carbon material prepared in the embodiment of the present application. As shown in Figure 2, the mulberry branch-derived hard carbon material prepared in Example 1 is rod-shaped, and the morphology is well maintained. As shown in Figure 3, the mulberry branch-derived hard carbon material prepared in Example 1 is rich in nitrogen and phosphorus elements.

Weigh 160 mg of hard carbon material, 20 mg of conductive agent Super-P, and 400 mg of binder PVDF (5% mass fraction solution). After fully mixing the three materials into a slurry, apply it evenly on a copper foil with a diameter of 1.2 cm. A copper foil loaded with active materials is used as the negative electrode of a sodium-ion battery.

See Figure 4, which is a rate performance diagram of a mulberry branch-derived hard carbon material provided in an embodiment of the present application; see Figure 5, which is a cycle performance diagram of a mulberry branch-derived hard carbon material provided in an embodiment of the present application. As shown in Figure 4 and combined with Figure 5, the mulberry branch-derived hard carbon material has a specific capacity of 290mAh/g at 0.1A/g; at a high current density of 10A/g, a high specific capacity of 80mAh/g; at 1A After 2000 cycles at /g current density, the capacity retention rate is as high as 80%, proving that mulberry branch-derived hard carbon has excellent electrochemical properties as an anode material for sodium-ion batteries.

Example 2:

The difference between this embodiment and Embodiment 1 is that the rotation speed of the ball mill is 450 r/min.

Example 3:

The difference between this example and Example 1 is that the ball milling time is 2 hours.

Example 4:

The difference between this embodiment and Embodiment 1 is that the carbonization temperature is 1100°C.

Example 5:

The difference between this embodiment and Embodiment 1 is that the carbonization temperature is 1300°C.

Example 6:

The difference between this embodiment and Example 1 is that the concentration of the hydrochloric acid solution is 3 mol/L.

Example 7:

The difference between this embodiment and Example 1 is that the concentration of the hydrochloric acid solution is 4 mol/L.

Example 8:

The difference between this embodiment and Embodiment 1 is that the temperature at which the acid solution is heated and stirred is 40°C.

Example 9:

The difference between this embodiment and Example 1 is that the acid solution is heated and stirred for 20 hours.

The button-type battery assembled with the negative electrode and sodium sheet prepared in the above example was subjected to the following electrochemical performance test, and the test results shown in Table 1 were obtained.

(1) Cycle performance test: Under normal temperature conditions, the prepared battery is tested on the LAND battery test system. The charge and discharge voltage range is 0.01~2V. The test batteries are charged and discharged at a constant current at a current density of 1A/g;

(2) Rate performance test: Under normal temperature conditions, the prepared batteries were tested on the LAND battery testing system, and the current densities of the batteries were tested at 0.1A/g, 0.2A/g, 0.5A/g, and 1A/g. , specific capacity under the conditions of 2A/g, 5A/g and 10A/g.

Table I:

As shown in Table 1, using the mulberry branch-derived hard carbon material prepared in Example 1 as the negative electrode of a sodium ion battery can achieve better rate performance and cycle performance.

The above are only specific embodiments of the present application. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, and they should be covered by the protection scope of the present application. The protection scope of this application shall be subject to the protection scope of the claims.

Claims (10)

1. A method for preparing hard carbon materials, which is characterized by comprising: Mulberry branch-derived hard carbon materials were prepared using mulberry branches as precursors. 2. The method according to claim 1, characterized in that, using mulberry branches as precursors to prepare mulberry branch-derived hard carbon materials includes: Under protective gas, the precursor powder is subjected to high-temperature carbonization treatment to obtain preliminary carbonized powder, and the precursor powder is mulberry branch powder; The preliminary carbonized powder is added to the hydrochloric acid solution, heated and stirred, washed and dried to obtain a mulberry branch-derived hard carbon material. 3. The method according to claim 2, characterized in that, before the obtained precursor powder is subjected to high-temperature carbonization treatment under protective gas to obtain preliminary carbonized powder, the precursor powder is mulberry branch powder. The above methods also include: The precursor powder is obtained by peeling and cutting the mulberry branches into sections, cleaning, drying and ball milling. 4. The method according to claim 3, characterized in that the drying temperature is 100-140°C and the drying time is 12-24 hours. 5. The method according to claim 3, characterized in that the ball milling speed is 400-480r/min, and the ball milling time is 1-4h. 6. The method according to claim 2, wherein the protective gas is argon and/or nitrogen, and the flow rate of the protective gas is 40-60 mL/min. 7. The method according to claim 2, characterized in that the temperature of the high-temperature carbonization treatment is 1000-1400°C, the time is 2-5h, the heating rate is 3-5°C/min, and it naturally drops to room temperature. 8. A sodium-ion battery negative electrode material, characterized in that it includes: A mulberry branch-derived hard carbon material prepared by the method described in any one of claims 1 to 7. 9. A sodium-ion battery negative electrode, characterized by comprising: Carrier, the carrier is in sheet form; A coating layer is uniformly coated on the carrier, and the coating layer includes a conductive agent, a binder and the sodium ion battery negative electrode material of claim 8. 10. A sodium-ion battery, characterized by comprising the sodium-ion battery negative electrode according to claim 9.