Selenium-doped MXene composite nano-material, and preparation method and use thereof

Abstract

The present invention discloses a selenium-doped MXene composite nano-material and a preparation method thereof, comprising the following steps: (1) adding MXene and an organic selenium source into a dispersant, and stirring to prepare a dispersion with a concentration of 1 mg/ml to 100 mg/ml; (2) transferring the dispersion into a reaction kettle, then heating, reacting, and then naturally cooling to a room temperature; (3) washing the product obtained in the step (2) with a cleaning agent, then centrifuging to collect a precipitate, and drying the precipitate under vacuum; and (4) placing the sample obtained in the step (3) into a tubular furnace for calcination, introducing protective gas, heating, and then cooling to a room temperature to obtain the selenium-doped MXene composite nano-material. The material prepared by the present invention has high specific surface area, good electrical conductivity, cycle stability performance, rate performance and high theoretical specific capacity.

Claims

1. A method of preparing a selenium-doped MXene composite nano-material, comprising: (1) adding a MXene and an organic selenium source into a dispersant, and stirring to prepare a dispersion with a concentration of 1 mg/ml to 100 mg/ml, wherein a mass ratio of the MXene to the organic selenium source is 1:1 to 10, wherein the dispersion concentration is the concentration of the MXene and the organic selenium source; (2) transferring the dispersion into a reaction kettle, then heating to 100° C. to 220° C., reacting for 10 h to 30 h, and then naturally cooling to a room temperature to form a product; (3) washing the product obtained in the step (2) with a cleaning agent, centrifuging to collect a precipitate, and drying the precipitate under vacuum for 6 h to 20 h; and (4) placing the precipitate obtained in the step (3) into a tubular furnace for calcination, introducing protective gas, heating to 300° C. to 1000° C. for 2 h to 8 h, and then naturally cooling to a room temperature to obtain the selenium-doped MXene composite nano-material.

2. The method of claim 1, wherein the organic selenium source is at least one selected from the group consisting of phenylselenol, dimethyl selenide and dibenzyl diselenide.

3. The method of claim 1, wherein the MXene is one or more selected from the group consisting of Ti.sub.2NT.sub.x, Mo.sub.2NT.sub.x, V.sub.2NT.sub.x, Ti.sub.2CT.sub.x, Mo.sub.2CT.sub.x and V.sub.2CT.sub.x.

4. The method of claim 1, wherein the dispersant is at least one selected from the group consisting of N,N-dimethylformamide and ethanol.

5. The method of claim 1, wherein the cleaning agent is at least one selected from the group consisting of water and ethanol.

6. The method of claim 1, wherein a selenium doping amount in the selenium-doped MXene composite nano-material is 3 wt % to 8 wt %.

7. The method of claim 1, wherein a stirring time in the step (1) is 1 h to 5 h.

8. The method of claim 1, wherein the dispersion is heated to 110° C. to 200° C. after being transferred into the reaction kettle, and reacted for 12 h to 20 h in the step (2).

9. The method of claim 1, wherein a rotation speed used for the centrifugation in the step (3) is 4000 rpm to 6000 rpm.

10. The method of claim 1, wherein a temperature of drying under vacuum is 50° C. to 70° C., and a vacuum degree does not exceed 133 Pa.

11. The method of claim 1, wherein the temperature is heated to 300° C. to 1000° C. with a heating speed of 3° C/min to 7° C/min in the step (4).

12. The method of claim 1, wherein the protective gas is N.sub.2 or Ar, and a gas flow speed is 180 ml/min to 300 ml/min.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a scanning electron micrograph of an undoped MXene material in a Comparative Example 1;

(2) FIG. 2 is a scanning electron micrograph of a selenium-doped MXene composite nano-material in Embodiment 1;

(3) FIG. 3 is a cycle performance chart of a cathode of an undoped MXene potassium ion battery in Comparative Example 1;

(4) FIG. 4 is a cycle performance chart of a cathode of a selenium-doped MXene potassium ion battery in Embodiment 1;

(5) FIG. 5 is a cycle performance chart of a cathode of a selenium-doped MXene potassium ion battery in Embodiment 2; and

(6) FIG. 6 is a cycle performance chart of a cathode of a selenium-doped MXene potassium ion battery in Embodiment 3.

DETAILED DESCRIPTION OF THE INVENTION

(7) In order to better explain the invention, the invention will be further described with reference to the following specific embodiments, but the present invention is not limited to the specific embodiments.

Embodiment 1

(8) A preparation method of a selenium-doped MXene composite nano-material, comprised the following steps: (1) 40 mg MXene material (Ti.sub.2CT.sub.x) and 40 mg phenylselenol were added into ethanol to prepare 1 mg/ml dispersion, and the dispersion was magnetically stirred at a room temperature for 1 h; (2) the dispersion obtained in the step (1) was transferred into a 100 ml reaction kettle, placed in an oven to react at 100° C. for 10 h, and naturally cooled to a room temperature; (3) the product obtained in the step (2) was collected, thoroughly cleaned with deionized water and anhydrous ethanol, and centrifuged, and then dried under vacuum at 60° C. for 6 h; (4) the sample obtained in the step (3) was placed into a tubular furnace for calcination, introduced with Ar gas at a gas flow speed of 180 ml/min, and a temperature rise rate of 5° C./min, further calcined at 300° C. for 2 h, and then naturally cooled to a room temperature to finally obtain the selenium-doped MXene composite nano-material; and (5) the selenium-doped MXene composite nano-material obtained in the step (4) was mixed with a polyvinylidene fluoride binder and carbon black according to a mass ratio of 8:1:1, a proper amount of N-methyl pyrrolidone solution was added, stirred and dispersed, a slurry was formed after uniformly stirring and was coated on a current collector, and dried under vacuum and sliced as an electrode material.

(9) The doped MXene in this embodiment had a specific surface area of 185.7 m.sup.2/g, an interlamellar spacing of 0.73 nm, and a selenium atom content of 3%, which were much larger than a specific surface area (42.3 m.sup.2/g) and an interlamellar spacing (0.61 nm) of the undoped MXene. At a current density of 100 mA/g, a reversible capacity of the selenium-doped MXene as an electrode material shown in FIG. 4 after 100 cycles was 220.5 mAh/g, which was 2.43 times that of an undoped MXene as an electrode shown in FIG. 3 (90.7 mAh/g).

Embodiment 2

(10) A preparation method of a selenium-doped MXene composite nano-material, comprised the following steps: (1) 200 mg MXene material (Ti.sub.2CT.sub.x) and 1000 mg phenylselenol were added into an ethanol solution to prepare 50 mg/ml dispersion, and the dispersion was magnetically stirred at a room temperature for 3 h; (2) the dispersion obtained in the step (1) was transferred into a 50 ml reaction kettle, placed in an oven to react at 160° C. for 20 h, and naturally cooled to a room temperature; (3) the product obtained in the step (2) was collected, thoroughly cleaned with deionized water and anhydrous ethanol, and centrifuged, and then dried under vacuum at 60° C. for 12 h; (4) the sample obtained in the step (3) was placed into a tubular furnace for calcination, introduced with Ar gas at a gas flow speed of 220 ml/min, and a temperature rise rate of 5° C./min, further calcined at 600° C. for 5 h, and then naturally cooled to a room temperature to obtain the selenium-doped MXene composite nano-material; and (5) the selenium-doped MXene composite nano-material obtained in the step (4) was mixed with a polyvinylidene fluoride binder and carbon black according to a mass ratio of 8:1:1, a proper amount of N-methyl pyrrolidone solution was added, stirred and dispersed, a slurry was formed after uniformly stirring and was coated on a current collector, and dried under vacuum and sliced as an electrode material.

(11) The selenium-doped MXene in this embodiment had a specific surface area of 326.2 m.sup.2/g, an interlamellar spacing of 0.77 nm, and a selenium atom content of 6%, which were much larger than the specific surface area (42.3 m.sup.2/g) and the interlamellar spacing (0.61 nm) of the undoped MXene. At a current density of 100 mA/g, a reversible capacity of the selenium-doped MXene as an electrode material shown in FIG. 5 after 100 cycles was 321 mAh/g, which was 3.54 times that of the undoped MXene as an electrode (90.7 mAh/g).

Embodiment 3

(12) A preparation method of a selenium-doped MXene composite nano-material, comprised the following steps: (1) 500 mg MXene material (Ti.sub.2CT.sub.x) and 5000 mg phenylselenol were added into ethanol to prepare 100 mg/ml dispersion, and the dispersion was magnetically stirred at a room temperature for 5 h; (2) the dispersion obtained in the step (1) was transferred into a 100 ml reaction kettle, placed in an oven to react at 220° C. for 30 h, and naturally cooled to a room temperature; (3) the product obtained in the step (2) was collected, thoroughly cleaned with deionized water and anhydrous ethanol, and centrifuged, and then dried under vacuum at 60° C. for 20 h; (4) the sample obtained in the step (3) was placed into a tubular furnace for calcination, introduced with Ar gas at a gas flow speed of 300 ml/min, and a temperature rise rate of 5° C./min, further calcined at 1000° C. for 8 h, and then naturally cooled to a room temperature to finally obtain the selenium-doped MXene composite nano-material; and (5) the selenium-doped MXene composite nano-material obtained in the step (4) was mixed with a polyvinylidene fluoride binder and carbon black according to a mass ratio of 8:1:1, a proper amount of N-methyl pyrrolidone solution was added, stirred and dispersed, a slurry was formed after uniformly stirring and was coated on a current collector, and dried under vacuum and sliced as an electrode material.

(13) The selenium-doped MXene in this embodiment has a specific surface area of 283.9 m.sup.2/g, an interlamellar spacing of 0.76 nm, and a selenium atom content of 8%, which were much larger than the specific surface area (42.3 m.sup.2/g) and the interlamellar spacing (0.61 nm) of the undoped MXene. At a current density of 100 mA/g, a reversible capacity of the selenium-doped MXene as an electrode material shown in FIG. 6 after 100 cycles was 298.1 mAh/g, which was 3.29 times that of the undoped MXene as an electrode (90.7 mAh/g).

Embodiment 4

(14) A preparation method of a selenium-doped MXene composite nano-material, comprised the following steps: (1) 400 mg MXene material (V.sub.2CT.sub.x) and 1000 mg organic selenium source (800 mg phenylselenol, 100 mg dimethyl selenide and 100 mg dibenzyl diselenide) were added into ethanol to prepare 40 mg/ml dispersion, and the dispersion was magnetically stirred at a room temperature for 3 h; (2) the dispersion obtained in the step (1) was transferred into a 50 ml reaction kettle, placed in an oven to react at 140° C. for 10 h, and naturally cooled to a room temperature; (3) the product obtained in the step (2) was collected, thoroughly cleaned with deionized water and anhydrous ethanol, and centrifuged, and then dried under vacuum at 60° C. for 6 h; (4) the sample obtained in the step (3) was placed into a tubular furnace for calcination, introduced with Ar gas at a gas flow speed of 200 ml/min, and a temperature rise rate of 5° C./min, further calcined at 300° C. for 2 h, and then naturally cooled to a room temperature to obtain the selenium-doped MXene composite nano-material; and (5) the selenium-doped MXene composite nano-material obtained in the step (4) was mixed with a polyvinylidene fluoride binder and carbon black according to a mass ratio of 8:1:1, a proper amount of N-methyl pyrrolidone solution was added, stirred and dispersed, a slurry was formed after uniformly stirring and was coated on a current collector, and dried under vacuum and sliced as an electrode material.

(15) At a current density of 100 mA/g, a reversible capacity of the selenium-doped MXene as a cathode material of a potassium ion battery in this embodiment after 100 cycles was 370 mAh/g, which was 4.08 times that of the undoped MXene as an electrode (90.7 mAh/g), and the doped MXene material in this embodiment had a very stable charge-discharge cycle characteristic.

Embodiment 5

(16) A preparation method of a selenium-doped MXene composite nano-material, comprised the following steps: (1) 600 mg MXene material (500 mg Ti.sub.2CT.sub.x and 100 mg Mo.sub.2CT.sub.x) and 1000 mg phenylselenol were added into ethanol to prepare 60 mg/ml dispersion, and the dispersion was magnetically stirred at a room temperature for 3 h; (2) the dispersion obtained in the step (1) was transferred into a 50 ml reaction kettle, placed in an oven to react at 170° C. for 13 h, and naturally cooled to a room temperature; (3) the product obtained in the step (2) was collected, thoroughly cleaned with deionized water and anhydrous ethanol, and centrifuged, and then dried under vacuum at 60° C. for 6 h; (4) the sample obtained in the step (3) was placed into a tubular furnace for calcination, introduced with Ar gas at a gas flow speed of 240 ml/min, and a temperature rise rate of 5° C./min, further calcined at 300° C. for 2 h, and then naturally cooled to a room temperature to obtain the selenium-doped MXene composite nano-material; and (5) the selenium-doped MXene composite nano-material obtained in the step (4) was mixed with a polyvinylidene fluoride binder and carbon black according to a mass ratio of 8:1:1, a proper amount of N-methyl pyrrolidone solution was added, stirred and dispersed, a slurry was formed after uniformly stirring and was coated on a current collector, and dried under vacuum and sliced as an electrode material.

(17) At a current density of 100 mA/g, a reversible capacity of the selenium-doped MXene as a cathode material of a potassium ion battery in this embodiment after 100 cycles was 357 mAh/g, which was 3.9 times that of the undoped MXene as an electrode (90.7 mAh/g), and the doped MXene material in this embodiment had a very stable charge-discharge cycle characteristic.

(18) Comparative Example 1: undoped MXene is used as a cathode of a potassium ion battery.

(19) Comparative Example 2: an inorganic selenium source (e.g., selenium powder)-doped MXene is used as a cathode of a potassium ion battery, wherein a doping process is the same as that in the Embodiment 2.

(20) TABLE-US-00001 TABLE 1 Performance test Specific Mass fraction surface Interlamellar of selenium Stable capacity area spacing atom content after 100 cycles (m.sup.2/g) (nm) (%) (mAh/g) Comparative Undoped MXene 42.3 0.61 0 90.7 Example 1 Embodiment 1 Selenium-doped 185.7 0.73 3 220.5 MXene Comparative Inorganic selenium 136.1 0.63 1 160 Example 2 source-doped MXene Embodiment 2 Selenium-doped 326.2 0.77 6 321 MXene Embodiment 3 Selenium-doped 283.9 0.76 8 298.1 MXene Embodiment 4 Selenium-doped 378.4 0.75 5 370 MXene Embodiment 5 Selenium-doped 360.2 0.76 7 357 MXene

(21) The foregoing descriptions are merely specific embodiments of the present invention, but are not intended to limit the protection scope of the present invention. All equivalent transformations made using the description of the invention, or being used directly or indirectly in other related technical fields, are similarly included in the protection scope of the present invention.