CN109817918B - Sulfur-doped MXene composite material, preparation method and application thereof - Google Patents

Abstract

The invention discloses a sulfur-doped MXene composite material and a preparation method thereof, wherein the preparation method comprises the following steps: (1) mixing MXene and a sulfur source according to a mass ratio of 1: 1-20, adding the mixture into deionized water, stirring and heating to prepare mixed liquid with the concentration of 5-80 mg/ml; (2) transferring the mixed solution into a reaction kettle, heating to 80-200 ℃, reacting for 4-36h, and then cooling to room temperature; (3) and (3) washing the product obtained in the step (2) with a detergent, centrifuging, and then carrying out vacuum drying to obtain the sulfur-doped MXene composite material. The sulfur-doped MXene composite material prepared by the method has the advantages of high structural stability, stable cycle performance, high charging and discharging coulombic efficiency and the like, and the prepared negative electrode material is moderate in potassium intercalation/deintercalation potential and good in cycle performance and multiplying power performance.

Description

Sulfur-doped MXene composite material, preparation method and application thereof

technical field

The invention belongs to the field of new energy materials, in particular to a preparation method of a sulfur-doped MXene composite material and its application in potassium ion batteries.

Background technique

With the rapid development of modern society, traditional energy sources are increasingly exhausted, and it becomes more urgent to find new clean energy sources. Due to its good chemical stability and electrochemical performance, lithium-ion batteries have been the core direction of the rechargeable battery field since its birth. However, lithium storage is limited, mining is difficult, and it is difficult to be widely used. In the search for an alternative to lithium-ion batteries, potassium, which has similar chemical properties and greater storage capacity, has begun to attract researchers' interest. It has important scientific significance for the research of high performance potassium ion battery anode.

The potassium ion radius is larger than the lithium ion radius, and the traditional commercial graphite electrode has a small interlayer spacing and cannot meet the rapid deintercalation of potassium ions. As a new type of two-dimensional layered material, MXene material is shaped like a "book page". The material has good electrical conductivity and high specific surface area, and is suitable as a negative electrode material for potassium ion batteries. However, the performance of pure MXene materials used as anode materials for potassium ion batteries is still unsatisfactory. Sulfur doping of MXene can increase the interlayer spacing and optimize the potassium ion diffusion channel, thereby improving the electrochemical performance of potassium ion batteries.

SUMMARY OF THE INVENTION

In view of the problems existing in the prior art, one of the objectives of the present invention is to provide a sulfur-doped MXene composite material. Another object of the present invention is to provide a method for preparing the above-mentioned sulfur-doped MXene composite material. Further, the present invention provides an application of a sulfur-doped MXene composite material, and the sulfur-doped MXene composite material is used as a negative electrode of a potassium ion battery.

The present invention adopts the following technical solutions:

A preparation method of a sulfur-doped MXene composite material, comprising the following steps:

(1) Add MXene and sulfur source into deionized water according to the mass ratio of 1:1-20 (for example, 1:2-15, 1:5-10, 1:6-8), stir and heat, and prepare the concentration of 5-80mg/ml (eg 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75mg/ml) mixture;

(2) Transfer the mixture into the reactor and heat to 80-200°C (for example, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C ℃, 190℃, 200℃), reaction 4-36h (for example, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32 , 34, 36h), then cooled to room temperature;

(3) washing the product obtained in step (2) with detergent, centrifuging, and then vacuum drying to obtain the sulfur-doped MXene composite material.

Further, the sulfur source is at least one of phenylene sulfide and 2-phenylethyl mercaptan, preferably phenylene sulfide, and preferably phenylene sulfide and 2-phenylethyl sulfide in a mass ratio of (2-5):1 alcohol.

Further, the MXene is one of Ti ₃ C ₂ T _x , Mo ₃ C ₂ T _x , V ₃ C ₂ T _x , Ti ₃ N ₂ T _x , Mo ₃ N ₂ T _x , V ₃ N ₂ T _x one or more.

Further, the sulfur doping amount in the sulfur-doped MXene composite material is 1wt%-20wt%, preferably 2wt%-12wt%.

Further, the sulfur doping amount in the sulfur-doped MXene composite material is 3wt%-15wt% (eg 3.5, 4.5, 5.5, 6.5, 7.5, 8.5, 9.5, 10.5, 11.5, 12.5, 13.5, 14.5wt%) .

Further, the detergent is at least one of deionized water and ethanol, for example, alternately washing with deionized water and ethanol 2-6 times, such as 3 times.

Further, the rotational speed used for centrifugation in step (3) is 3000-3500r/min, for example, 3200r/min, and centrifugation is performed for 2-4min.

Further, the temperature of vacuum drying in step (3) is 50-70°C, preferably 60°C, and the drying time is 8-24h (for example, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24h), the degree of vacuum does not exceed 135Pa, such as not more than 133Pa, such as not more than 125, 115, 105, 95, 85Pa.

A method for preparing a sulfur-doped MXene composite material The sulfur-doped MXene composite material is prepared.

An application of a sulfur-doped MXene composite material, the sulfur-doped MXene composite material is used as a negative electrode of a potassium ion battery.

Beneficial effects of the present invention:

(1) The sulfur-doped MXene composite material prepared by the present invention has the advantages of high structural stability, stable cycle performance, good rate performance, and high charge-discharge coulombic efficiency, and the prepared negative electrode material has moderate intercalation/depotassium potential and cycle performance. and good rate performance;

(2) The preparation method of the present invention is simple, the doping amount of sulfur element is controllable, and is suitable for large-scale application.

Description of drawings

Fig. 1 is the scanning electron microscope image of undoped MXene material in Comparative Example 1;

2 is a scanning electron microscope image of the sulfur-doped MXene composite material in Example 1;

Fig. 3 is the cycle performance diagram of sulfur-doped MXene composite material as the negative electrode of potassium ion battery in Example 1;

FIG. 4 is a graph of the cycle performance of the undoped MXene material in Comparative Example 1 as the negative electrode of the potassium ion battery.

Detailed ways

In order to better explain the present invention, further description will now be made in conjunction with the following specific embodiments, but the present invention is not limited to the specific embodiments.

Example 1

A preparation method of a sulfur-doped MXene composite material, comprising the following steps:

(1) Weigh 0.1 g of Ti ₃ C ₂ T _x and 0.1 g of phenylene sulfide into deionized water, heat to 50° C. and stir magnetically for 1 hour to obtain a mixed solution.

(2) The mixed solution was moved to the reaction kettle and sealed, and then placed in an oven, and the reaction temperature was adjusted to 80° C. and the reaction time was 4 hours.

(3) The obtained product was washed 3 times alternately with deionized water and ethanol, and centrifuged at a centrifugal speed of 3000 r/min for 2 min, and finally put into a vacuum drying box and dried at 60° C. for 8 h.

(4) Preparation of negative electrode for potassium ion battery: The obtained sulfur-doped MXene is mixed with polyvinylidene fluoride binder and carbon black in a mass ratio of 8:1:1, and an appropriate amount of N-methylpyrrolidone is added. After stirring evenly, a slurry is formed and coated on the current collector. After vacuum drying and slicing, a sulfur-doped MXene battery negative electrode is prepared.

(5) Figure 1 shows that the undoped MXene has an "accordion" morphology, and after doping, Figure 2 shows the morphology of the doped MXene in this example. The specific surface area of doped MXene is 172m ² /g, the interlayer spacing is 0.71nm, and the content of sulfur atoms is 1%, which is much larger than the specific surface area (40.8m ² /g) and interlayer spacing (0.64nm) of undoped MXene; Figure 3 shows that the reversible capacity of MXene doped in this example is 251mAh/g after 100 cycles at a current density of 100mA/g, which is the reversible capacity (93.8mAh/g) of the negative electrode of the undoped MXene potassium ion battery in Figure 4. 2.6 times.

Example 2

A preparation method of a sulfur-doped MXene composite material, comprising the following steps:

(1) Weigh 0.2 g of Ti ₃ C ₂ T _x and 2 g of phenylene sulfide into deionized water, heat to 60° C., and magnetically stir for 3 hours to obtain a mixed solution.

(2) The mixed solution was moved to the reaction kettle and sealed, and then placed in an oven, and the reaction temperature was adjusted to 160° C. and the reaction time was 18 hours.

(3) The obtained product was washed alternately with deionized water and ethanol for 3 times, and centrifuged at a centrifugal speed of 3250 r/min for 3 min, and finally put into a vacuum drying box and dried at 60° C. for 16 h.

(4) Preparation of negative electrode for potassium ion battery: The obtained sulfur-doped MXene is mixed with polyvinylidene fluoride binder and carbon black in a mass ratio of 8:1:1, and an appropriate amount of N-methylpyrrolidone is added. After stirring evenly, a slurry is formed and coated on the current collector. After vacuum drying and slicing, a sulfur-doped MXene battery negative electrode is prepared.

(5) The specific surface area of the doped MXene in this example is 365 m ² /g, the interlayer spacing is 0.82 nm, and the content of sulfur atoms is 10%, which is much larger than the specific surface area (40.8 m ² /g) and layer of undoped MXene. Spacing (0.64nm); under the current density of 100mA/g, the reversible capacity of MXene doped in this example is 363mAh/g after 100 cycles, which is the negative electrode of undoped MXene potassium ion battery (93.8mAh/g) 3.8 times.

Example 3

A preparation method of a sulfur-doped MXene composite material, comprising the following steps:

(1) Weigh 0.5 g of Ti ₃ C ₂ T _x and 10 g of phenylene sulfide into deionized water, heat to 70° C., and magnetically stir for 5 hours to obtain a mixed solution.

(2) The mixed solution was moved to the reaction kettle and sealed, and then placed in an oven, and the reaction temperature was adjusted to 200° C. and the reaction time was 36h.

(3) The obtained product was washed alternately with deionized water and ethanol for 3 times, and centrifuged at a centrifugal speed of 3500 r/min for 4 min, and finally placed in a vacuum drying box and dried at 60° C. for 24 h.

(4) Preparation of negative electrode for potassium ion battery: The obtained sulfur-doped MXene is mixed with polyvinylidene fluoride binder and carbon black in a mass ratio of 8:1:1, and an appropriate amount of N-methylpyrrolidone is added. After stirring evenly, a slurry is formed and coated on the current collector. After vacuum drying and slicing, a sulfur-doped MXene battery negative electrode is prepared.

(5) The specific surface area of the doped MXene in this example is 291 m ² /g, the interlayer spacing is 0.75 nm, and the sulfur atom content is 20%, which is much larger than the specific surface area (40.8 m ² /g), layer spacing and 20% of the undoped MXene. Spacing (0.64nm); under the current density of 100mA/g, the reversible capacity of MXene doped in this example is 301mAh/g after 100 cycles, which is the negative electrode of undoped MXene potassium ion battery (93.8mAh/g) 3.2 times.

Example 4

A preparation method of a sulfur-doped MXene composite material, comprising the following steps:

(1) Weigh 0.1 g of Ti ₃ C ₂ T _x , 0.1 g of Mo ₃ C ₂ T _x and 2 g of phenylene sulfide into deionized water, heat to 60° C., and magnetically stir for 3 hours to obtain a mixed solution.

(2) The mixed solution was moved to the reaction kettle and sealed, and then placed in an oven, and the reaction temperature was adjusted to 100° C. and the reaction time was 6 h.

(3) The obtained product was washed alternately with deionized water and ethanol for 3 times, and centrifuged at a centrifugal speed of 3250 r/min for 3 min, and finally put into a vacuum drying box and dried at 60° C. for 10 h.

(4) Preparation of negative electrode for potassium ion battery: The obtained sulfur-doped MXene is mixed with polyvinylidene fluoride binder and carbon black in a mass ratio of 8:1:1, and an appropriate amount of N-methylpyrrolidone is added. After stirring evenly, a slurry is formed and coated on the current collector. After vacuum drying and slicing, a sulfur-doped MXene battery negative electrode is prepared.

(5) Under the current density of 100 mA/g, the reversible capacity of the MXene doped in this example after 100 cycles is 372 mAh/g, which is 4.0 times that of the negative electrode (93.8 mAh/g) of the undoped MXene potassium ion battery. .

Example 5

A preparation method of a sulfur-doped MXene composite material, comprising the following steps:

(1) 0.2 g of V ₃ C ₂ T _x and 2 g of 2-phenylethanethiol were weighed into deionized water, heated to 60° C., and magnetically stirred for 3 hours to obtain a mixed solution.

(2) The mixed solution was moved to the reaction kettle and sealed, and then placed in an oven, and the reaction temperature was adjusted to 120° C. and the reaction time was 8h.

(3) The obtained product was washed alternately with deionized water and ethanol for 3 times, and centrifuged at a centrifugal speed of 3250 r/min for 3 min, and finally put into a vacuum drying box and dried at 60° C. for 8 h.

(4) Preparation of negative electrode for potassium ion battery: The obtained sulfur-doped MXene is mixed with polyvinylidene fluoride binder and carbon black in a mass ratio of 8:1:1, and an appropriate amount of N-methylpyrrolidone is added. After stirring evenly, a slurry is formed and coated on the current collector. After vacuum drying and slicing, a sulfur-doped MXene battery negative electrode is prepared.

(5) Under the current density of 100 mA/g, the reversible capacity of the MXene doped in this example after 100 cycles is 368 mAh/g, which is 3.9 times that of the negative electrode (93.8 mAh/g) of the undoped MXene potassium ion battery. .

Comparative Example 1: Undoped MXene potassium ion battery negative electrode, the process of preparing the potassium ion battery negative electrode is the same as that of Example 2.

Table 1: Performance Testing

The above descriptions are only specific embodiments of the present invention, and are not intended to limit the scope of the present invention. All equivalent transformations made by the present invention, or directly or indirectly applied in other related technical fields, are similarly included in the present invention. within the scope of patent protection.

Claims (4)

1. The preparation method of the sulfur-doped MXene potassium ion battery negative electrode composite material is characterized by comprising the following steps of:

(1) mixing MXene and a sulfur source according to a mass ratio of 1: 5-10, adding the mixture into deionized water, stirring and heating the mixture to prepare mixed liquid with the concentration of 5-80 mg/ml;

(2) transferring the mixed solution into a reaction kettle, heating to 80-200 ℃, reacting for 4-36h, and then cooling to room temperature;

(3) washing the product obtained in the step (2) with a detergent, centrifuging, and then carrying out vacuum drying to obtain the sulfur-doped MXene potassium ion battery negative electrode composite material;

the sulfur source is diphenyl sulfide;

the MXene is Ti₃C₂T_xAnd Mo₃C₂T_x；

The sulfur doping amount of the sulfur-doped MXene potassium ion battery negative electrode composite material is 9 wt%;

the detergent is at least one of deionized water and ethanol;

the rotation speed for centrifugation in the step (3) is 3000-.

2. The preparation method of the sulfur-doped MXene potassium ion battery anode composite material according to claim 1, wherein the temperature of vacuum drying in step (3) is 50-70 ℃, the drying time is 8-24h, and the vacuum degree is not more than 135 Pa.

3. The sulfur-doped MXene potassium ion battery anode composite material prepared according to the preparation method of any one of claims 1-2.

4. The application of the sulfur-doped MXene potassium ion battery anode composite material according to claim 3, wherein the sulfur-doped MXene potassium ion battery anode composite material is used for a potassium ion battery anode.

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