CN117023556A - Sodium battery negative electrode material prepared from rubber leftover materials, and preparation method and application thereof - Google Patents

Abstract

The invention belongs to the technical field of sodium batteries. The invention discloses a sodium battery negative electrode material prepared from rubber scraps and its preparation method and application. The method of preparing sodium battery negative electrode material from rubber scraps of the present invention includes the following steps: first mixing rubber scrap powder and urea and then calcining to obtain rubber scrap carbide; rubber scrap powder and potassium hydroxide solution after second mixing After drying and carbonization in sequence, rubber scrap-based hard carbon is obtained, which is the negative electrode material of the sodium battery. The invention utilizes rubber scraps to greatly reduce costs. The rubber scrap-based hard carbon obtained by the present invention is used as a sodium battery negative electrode material to prepare a sodium battery with excellent electrical properties and cycle stability.

Description

A sodium battery negative electrode material prepared from rubber scraps and its preparation method and application

Technical field

The invention relates to the technical field of sodium batteries, and in particular to a sodium battery negative electrode material prepared from rubber scraps and its preparation method and application.

Background technique

With the development of large-scale energy storage and new energy vehicles, the demand for lithium-ion batteries is increasing day by day, and the consequent supply problem of metallic lithium resources is becoming increasingly severe. Sodium resources in the earth's crust are abundant, cheap, and widely distributed. Sodium batteries are battery systems with great potential for development. In recent years, they have received widespread attention and attention from domestic and foreign researchers. Sodium batteries have excellent electrochemical properties and can well meet the application needs of power storage, especially large-scale energy storage, and can meet the growing application needs in the fields of large-scale energy storage and new energy vehicles.

Sodium batteries are composed of positive electrode materials, negative electrode materials, electrolytes and separators. Among them, the negative electrode material of sodium batteries is the carrier for sodium ions to be deintercalated. Its performance directly determines the performance of sodium batteries. The ideal sodium battery negative electrode The material needs to have a relatively low discharge potential to obtain a high output voltage, to provide enough sodium storage sites to obtain a high capacity, and to have a stable structure that can resist the stress generated during the deintercalation process of sodium ions. , thereby achieving long cycle life, good conductivity and high rate performance. Currently, commonly used sodium battery anode materials are carbon materials, transition metal oxides, transition metal sulfides, phosphides, and tungsten diselenide. The above-mentioned negative electrode materials have problems such as poor electrical properties and poor cycle stability. Severe volume changes will occur during repeated charge and discharge processes, resulting in capacity decline, and the preparation cost of the negative electrode materials is high. Therefore, there is an urgent need in this field to develop a negative electrode material for sodium batteries with excellent electrical properties, cycle stability, and low cost.

Contents of the invention

The purpose of the present invention is to provide a sodium battery negative electrode material prepared from rubber scraps and its preparation method and application, so as to solve the problem that the existing negative electrode materials for sodium batteries have poor electrical properties and poor cycle stability, which may occur during repeated charging and discharging processes. Severe volume changes occur, leading to capacity fading, and the preparation cost of negative electrode materials is high.

In order to achieve the above objects, the present invention adopts the following technical solutions:

The invention provides a method for preparing sodium battery negative electrode materials from rubber scraps, which includes the following steps:

Rubber scrap powder and urea are first mixed and then calcined to obtain rubber scrap carbide; rubber scrap carbide and potassium hydroxide solution are mixed for the second time and then dried and carbonized sequentially to obtain rubber scrap-based hard carbon.

Preferably, the particle size of the rubber scrap powder is 90-120 mesh; the mass ratio of the rubber scrap powder and urea is 3-5:1.

Preferably, the first mixing speed is 300-500 r/min, the first mixing time is 3-5 hours; the calcination temperature is 350-500°C, and the calcination time is 2.5-4 hours.

Preferably, before the second mixing, the rubber scrap carbide is ball-milled; the rotation speed of the ball mill is 300 to 500 r/min, and the ball milling time is 3 to 5 hours.

Preferably, the concentration of the potassium hydroxide solution is 0.5-2mol/L; the mass-volume ratio of the rubber scrap powder and the potassium hydroxide solution is 100-200g:1L.

Preferably, the second mixing speed is 500 to 700 r/min, and the second mixing time is 10 to 14 hours.

Preferably, the drying temperature is 100-110°C, and the drying time is 7-9 hours; the carbonization is performed under protective gas, and the protective gas is nitrogen or argon; the carbonizing temperature is 850-1000°C. The carbonization time is 1 to 4 hours; before drying, the mixture obtained by the second mixing is suction filtered.

Preferably, after the carbonization is completed, the product obtained by carbonization is washed with hydrochloric acid, water and ethanol in sequence, and the number of washings is 2 to 6 times.

The present invention also provides a sodium battery negative electrode material prepared by the method of preparing sodium battery negative electrode material from rubber scraps. The sodium battery negative electrode material is rubber scraps-based hard carbon.

The invention also provides the application of the sodium battery negative electrode material in preparing sodium batteries.

It can be seen from the above technical solutions that compared with the prior art, the beneficial effects of the present invention are as follows:

(1) The rubber scraps of the present invention contain a large amount of heteroatoms sulfur and nitrogen, so they can provide a higher heteroatom doping amount and improve the conductivity and electrochemical properties of the resulting negative electrode material; (2) Rubber scraps are rich in resources, The price is low, and the preparation of rubber scrap-based hard carbon with high specific surface area is highly economical and can reduce the raw material cost of sodium battery anode materials; (3) Rubber scraps are high molecular polymers, which can be used in the process of preparing rubber scrap-based hard carbon. A rich 3D network pore structure is formed, which is beneficial to the storage of sodium ions and improves the capacity and stability of the resulting sodium battery.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the provided drawings without exerting creative efforts.

Figure 1 is the adsorption curve of rubber scrap-based hard carbon obtained in Example 1;

Figure 2 is a pore size distribution diagram of the rubber scrap-based hard carbon obtained in Example 1;

Figure 3 is a TEM image of the rubber scrap-based hard carbon obtained in Example 1;

Figure 4 is an SEM image of the rubber scrap-based hard carbon obtained in Example 1.

Detailed ways

The invention provides a method for preparing sodium battery negative electrode materials from rubber scraps, which includes the following steps:

Rubber scrap powder and urea are first mixed and then calcined to obtain rubber scrap carbide; rubber scrap carbide and potassium hydroxide solution are mixed for the second time and then dried and carbonized sequentially to obtain rubber scrap-based hard carbon.

In the present invention, the particle size of the rubber scrap powder is preferably 90-120 mesh, more preferably 95-110 mesh, and more preferably 100-105 mesh; the mass ratio of the rubber scrap powder and urea is preferably 3-110 mesh. 5:1, more preferably 3.5-4.5:1, more preferably 4-4.2:1.

In the present invention, the rotation speed of the first mixing is preferably 300-500r/min, more preferably 320-480r/min, more preferably 400-450r/min; the time of the first mixing is preferably 3-5h, further Preferably it is 3.5-4.5h, more preferably 4h; the calcination temperature is preferably 350-500°C, further preferably 380-450°C, more preferably 400-430°C; the calcination time is preferably 2.5-4h, further Preferably it is 170-200min, More preferably, it is 180-190min.

In the present invention, before the second mixing, the rubber scrap carbide is ball milled; the rotation speed of the ball mill is preferably 300 to 500 r/min, more preferably 320 to 480 r/min, and more preferably 400 to 450 r/min; The time is preferably 3 to 5 hours, more preferably 3.5 to 4.5 hours, and more preferably 4 hours.

In the present invention, the concentration of the potassium hydroxide solution is preferably 0.5 to 2 mol/L, more preferably 0.8 to 1.6 mol/L, and more preferably 1 to 1.5 mol/L; the rubber scrap powder and potassium hydroxide The mass-volume ratio of the solution is preferably 100-200g:1L, more preferably 110-160g:1L, and more preferably 120-150g:1L.

In the present invention, the second mixing speed is preferably 500-700r/min, more preferably 550-650r/min, more preferably 600-620r/min; the second mixing time is preferably 10-14h, further Preferably it is 11-13h, More preferably, it is 12h.

In the present invention, the drying temperature is preferably 100-110°C, more preferably 102-109°C, and more preferably 105-107°C; the drying time is preferably 7-9h, further preferably 7.5-8.5h. More preferably, it is 8 hours; the carbonization is carried out under a protective gas, and the protective gas is preferably nitrogen or argon; the temperature of the carbonization is preferably 850-1000°C, further preferably 880-950°C, and more preferably 900-930°C ; The carbonization time is preferably 1 to 4 hours, more preferably 2 to 3 hours, and more preferably 2.5 hours; before drying, the mixture obtained by the second mixing is subjected to suction filtration, and the purpose of suction filtration is to separate the mixture from solid and liquid. solid powder among them.

In the present invention, after the carbonization is completed, the product obtained by carbonization is washed with hydrochloric acid, water and ethanol in sequence. The number of washings is preferably 2 to 6 times, more preferably 3 to 5 times, and more preferably 4 times; Among them, washing with hydrochloric acid, water and ethanol in sequence is one wash; the mass fraction of hydrochloric acid is preferably 3 to 7%, more preferably 4 to 6%, and more preferably 5%; ethanol is preferably absolute ethanol.

The present invention also provides a sodium battery negative electrode material prepared by the method of preparing sodium battery negative electrode material from rubber scraps. The sodium battery negative electrode material is rubber scraps-based hard carbon.

The invention also provides the application of the sodium battery negative electrode material in preparing sodium batteries.

The technical solutions provided by the present invention will be described in detail below with reference to the examples, but they should not be understood as limiting the protection scope of the present invention.

Example 1

Use a 400r/min liquid nitrogen ultra-low temperature grinder to physically crush the rubber scraps to obtain 100-mesh rubber scraps powder; ball mill and mix 20g of the above rubber scraps powder and 5g of urea for 4 hours at a ball mill speed of 400r/min. After the materials are finished, the resulting mixture is placed in an air furnace and calcined at 400°C for 3 hours to obtain rubber scrap carbide; the rubber scrap carbide is ball milled at a ball mill speed of 400 r/min for 4 hours to obtain powdered material; the powder is The material was dispersed in 0.2L potassium hydroxide solution with a concentration of 1 mol/L, stirred magnetically at a rotation speed of 600r/min for 12h, and then filtered under normal pressure to obtain black powder; the black powder was placed in a vacuum drying box (vacuum degree (1 torr), dried at 105°C for 8 hours, then placed in a nitrogen furnace and carbonized at 900°C for 2 hours to obtain a porous material; the porous material was washed sequentially with 5wt% hydrochloric acid solution, water and absolute ethanol, and after washing 3 times Rubber scrap-based hard carbon was obtained.

The adsorption capacity of the rubber scrap-based hard carbon obtained in this example was tested. The test method and results are as follows.

Test method: Use the Mike ASAP2460 physical adsorption analyzer to measure the adsorption amount of rubber scrap-based hard carbon. The results are shown in Figure 1.

As can be seen from Figure 1, the specific surface area of the obtained rubber scrap-based hard carbon reaches 2165m ² /g, with rich pore structure and excellent adsorption performance.

The pore size distribution of the rubber scrap-based hard carbon obtained in this example was analyzed, and the results are shown in Figure 2.

As can be seen from Figure 2, the pores of the obtained rubber scrap-based hard carbon are micropores, and the pore diameter is mainly concentrated at about 1 nm, which is conducive to the storage of sodium ions.

The rubber scrap-based hard carbon obtained in this example was analyzed by transmission electron microscopy and scanning electron microscopy, and the results are shown in Figures 3 and 4.

It can be seen from Figures 3 and 4 that the obtained rubber scrap-based hard carbon has a rich pore structure with micropores and mesopores.

Example 2

Use a 400r/min liquid nitrogen ultra-low temperature grinder to physically crush the rubber scraps to obtain 110 mesh rubber scraps powder; ball mill and mix 18g of the above rubber scraps powder and 5g of urea for 3 hours at a ball mill speed of 400r/min. After the materials are finished, the resulting mixture is placed in an air furnace and calcined at 360°C for 3 hours to obtain rubber scrap carbide; the rubber scrap carbide is ball milled at a ball mill speed of 400 r/min for 3 hours to obtain a powdered material; the powder is The material was dispersed in 0.18L potassium hydroxide solution with a concentration of 1.5 mol/L, stirred magnetically at a rotation speed of 600r/min for 11 hours, and then filtered to obtain black powder; the black powder was placed in a vacuum drying box (vacuum degree: 1torr), dried at 102°C for 8 hours, then placed in a nitrogen furnace and carbonized at 850°C for 2.5 hours to obtain a porous material; the porous material was washed sequentially with 5wt% hydrochloric acid solution, water and absolute ethanol, and after washing 4 times Rubber scrap-based hard carbon was obtained.

Example 3

Use a 400r/min liquid nitrogen ultra-low temperature grinder to physically crush the rubber scraps to obtain 120 mesh rubber scraps powder; ball mill and mix 24g of the above rubber scraps powder and 5g of urea for 4 hours at a ball mill speed of 400r/min. After the material is finished, the resulting mixture is placed in an air furnace and calcined at 500°C for 3 hours to obtain rubber scrap carbide; the rubber scrap carbide is ball milled at a ball mill speed of 400 r/min for 4 hours to obtain powdered material; the powder is The material was dispersed in 0.24L of potassium hydroxide solution with a concentration of 1.8mol/L, stirred magnetically at a rotation speed of 600r/min for 12h, and then filtered to obtain black powder; the black powder was placed in a vacuum drying box (vacuum degree: 1torr), dried at 109°C for 7 hours, then placed in a nitrogen furnace and carbonized at 950°C for 2 hours to obtain a porous material; the porous material was washed sequentially with 5wt% hydrochloric acid solution, water and absolute ethanol, and was obtained after washing 4 times. Rubber scraps based hard carbon.

Example 4

Use a 400r/min liquid nitrogen ultra-low temperature grinder to physically crush the rubber scraps to obtain 90-mesh rubber scraps powder; ball mill and mix 20g of the above rubber scraps powder and 5g of urea for 4 hours at a ball mill speed of 450r/min. After the material is finished, the resulting mixture is placed in an air furnace and calcined at 450°C for 2.5 hours to obtain rubber scrap carbide; the rubber scrap carbide is ball milled at a ball mill speed of 460 r/min for 4 hours to obtain powdered material; The powdery material was dispersed in 0.2L of potassium hydroxide solution with a concentration of 0.9mol/L, stirred magnetically at a rotation speed of 600r/min for 12h, and then filtered to obtain black powder; the black powder was placed in a vacuum drying box (vacuum degree (1 torr), dried at 103°C for 9 hours, then placed in a nitrogen furnace and carbonized at 980°C for 2 hours to obtain a porous material; the porous material was washed sequentially with 5wt% hydrochloric acid solution, water and absolute ethanol, and after washing 5 times Rubber scrap-based hard carbon was obtained.

Comparative example 1

Replace the amount of rubber scrap powder in Example 1 with 10 g, and the other contents are the same as Example 1.

Comparative example 2

The amount of rubber scrap powder in Example 1 was replaced with 30g, and the rest was the same as Example 1.

Comparative example 3

Replace the calcination temperature in Example 1 with 700°C and the calcination time with 2 hours. The rest are the same as Example 1.

Comparative example 4

Replace the calcination temperature in Example 1 with 300°C and the calcination time with 5 hours. The rest are the same as Example 1.

Comparative example 5

The amount of potassium hydroxide solution in Example 1 was replaced with 0.4L, and the others were the same as Example 1.

Comparative example 6

The carbonization temperature in Example 1 was replaced with 700°C, the calcination time was replaced with 7 hours, and the others were the same as Example 1.

Comparative example 7

The carbonization temperature in Example 1 was replaced with 1100°C, the calcination time was replaced with 30 minutes, and the others were the same as Example 1.

Comparative example 8

The drying temperature in Example 1 was replaced with 80°C, and the others were the same as Example 1.

The rubber scrap-based hard carbon obtained in Examples 1 to 4 and the hard carbon obtained in Comparative Examples 1 to 8 were used as negative electrode materials for sodium batteries using the following method to prepare sodium batteries, which were marked as samples 1 to 12 respectively.

Preparation of sodium battery:

The materials used are as follows:

Working electrode: Mix and grind the sodium battery negative electrode material, acetylene black and polyvinylidene fluoride with a mass ratio of 8:1:1 at a rotation speed of 400r/min. Add N-methylpyrrolidone during the grinding process to obtain a solid. A slurry with a content of 65%; apply the slurry on a copper sheet (coating thickness is 100 μm), and dry it at 80°C to obtain a working electrode;

Positive electrode: sodium tablet;

Electrolyte: Prepare a mixed solution of propylene carbonate and diethyl carbonate with a volume ratio of 3:1; dissolve sodium perchlorate in the mixed solution to prepare a solution with a sodium perchlorate concentration of 1 mol/L, add it to the solution Add fluoroethylene carbonate so that the mass fraction of fluoroethylene carbonate is 5% to obtain an electrolyte; fluoroethylene carbonate is used as an additive to form a relatively tight solid electrolyte interface film;

Diaphragm: fiberglass diaphragm;

Reference electrode: sodium tablet;

Battery case: CR2032 battery case;

gasket;

The above materials were placed in a glove box filled with argon and assembled into a half-cell to obtain a sodium battery.

Perform performance tests on samples 1 to 12. The current density during the detection process is 1A/g. The results are shown in Table 1.

Table 1 Performance test results of samples 1 to 12

As can be seen from Table 1, the rubber scrap-based hard carbon obtained in the present invention is used as a sodium battery negative electrode material to prepare a sodium battery with excellent electrical properties and cycle stability.

The above are only preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of the present invention. These improvements and modifications can also be made. should be regarded as the protection scope of the present invention.

Claims (10)

1. A method for preparing sodium battery negative electrode materials from rubber scraps, which is characterized by comprising the following steps: Rubber scrap powder and urea are first mixed and then calcined to obtain rubber scrap carbide; rubber scrap carbide and potassium hydroxide solution are mixed for the second time and then dried and carbonized sequentially to obtain rubber scrap-based hard carbon. 2. The method for preparing sodium battery negative electrode material from rubber scraps according to claim 1, characterized in that the particle size of the rubber scraps powder is 90-120 mesh; the mass ratio of the rubber scraps powder and urea is 3-5 :1. 3. The method for preparing sodium battery negative electrode material from rubber scraps according to claim 2, characterized in that the rotation speed of the first mixing is 300~500r/min, and the time of the first mixing is 3~5h; the calcined The temperature is 350~500℃, and the calcination time is 2.5~4h. 4. The method for preparing sodium battery negative electrode material from rubber scraps according to any one of claims 1 to 3, characterized in that, before the second mixing, the carbide of rubber scraps is ball milled; the speed of the ball mill is 300 to 500r/ min, the ball milling time is 3 to 5 hours. 5. The method for preparing sodium battery negative electrode material from rubber scraps according to claim 4, characterized in that the concentration of the potassium hydroxide solution is 0.5 ~ 2mol/L; the mass volume of the rubber scraps powder and the potassium hydroxide solution The ratio is 100~200g:1L. 6. The method for preparing sodium battery negative electrode material from rubber scraps according to claim 1, 2, 3 or 5, characterized in that the rotation speed of the second mixing is 500~700r/min, and the time of the second mixing is 10~ 14h. 7. The method for preparing sodium battery negative electrode material from rubber scraps according to claim 6, characterized in that the drying temperature is 100-110°C and the drying time is 7-9h; the carbonization is carried out under protective gas. The protective gas is nitrogen or argon; the carbonization temperature is 850-1000°C, and the carbonization time is 1-4 hours; before drying, the mixture obtained by the second mixing is suction filtered. 8. The method for preparing sodium battery negative electrode material from rubber scraps according to claim 7, characterized in that after the carbonization is completed, the product obtained by carbonization is washed with hydrochloric acid, water and ethanol in sequence, and the number of washings is 2 to 6 Second-rate. 9. The sodium battery negative electrode material prepared by the method of preparing sodium battery negative electrode material from rubber scraps according to any one of claims 1 to 8, characterized in that the sodium battery negative electrode material is hard carbon based on rubber scraps. 10. Application of the sodium battery negative electrode material according to claim 9 in the preparation of sodium batteries.