阅读说明：本技术 一种通过破坏石墨烯周期性提高氟化碳放电电压的方法 (Method for periodically improving carbon fluoride discharge voltage by destroying graphene ) 是由 封伟 孔令辰 李瑀 彭聪 于 2019-09-18 设计创作，主要内容包括：本发明公开一种通过破坏石墨烯周期性提高氟化碳放电电压的方法,使用等离子轰击或者激光刻蚀的方法对石墨烯进行周期性结构的破坏,在进行氟化处理,以得到氟化石墨烯材料。本发明通过破坏石墨烯周期性以提高氟化碳放电电压,该方法操作简单有效。制备的氟化碳材料同时具有C-F离子键和高比容量,其放电电压高于商业化氟化石墨烯材料。(The invention discloses a method for periodically improving carbon fluoride discharge voltage by destroying graphene, which is characterized in that a periodic structure of graphene is destroyed by using a plasma bombardment or laser etching method, and then fluorination treatment is carried out, so as to obtain a fluorinated graphene material. The method improves the carbon fluoride discharge voltage by destroying the periodicity of the graphene, and is simple and effective to operate. The prepared carbon fluoride material has C-F ionic bond and high specific capacity, and the discharge voltage of the carbon fluoride material is higher than that of a commercial fluorinated graphene material.)

1. A method for periodically improving the discharge voltage of carbon fluoride by destroying graphene is characterized by comprising the following steps:

step 1, carrying out periodic structure damage on graphene by using a plasma bombardment or laser etching method;

and 2, fluorinating the graphene treated in the step 1 by using fluorine gas to obtain a carbon fluoride material.

2. The method for periodically increasing the discharge voltage of carbon fluoride according to claim 1, wherein the plasma bombardment is performed, the maximum discharge voltage is found by changing the bombardment current, the gas ionization voltage is 1000 +/-50V, the ion focusing voltage is 500 +/-50V, and the vacuum degree of the plasma bombardment is 10^-2Pa, the bombardment ions are argon plasma, and the bombardment current is 40-80 mA.

3. The method of claim 1, wherein the laser etching is performed to find the maximum discharge voltage by changing the peak power, the laser wavelength is 1064nm, the pulse width is 75 ± 5ns, the repetition frequency is 1-30kHz, the spot diameter is 70 ± 5 μm, the shift step size is 2 ± 0.1 μm, and the peak power is 50-80 kW.

4. The method for periodically increasing the discharge voltage of carbon fluoride according to any one of claims 1 to 3, wherein in the step 2, the graphene treated in the step 1 is placed in a heating zone of a tube furnace, and after the tube furnace is installed and the airtightness of the tube furnace is checked, an inert protective gas is introduced into the tube to remove the air in the tube furnace; heating to 300-500 ℃, vacuumizing, introducing a mixed gas of fluorine gas and hydrogen gas, taking an inert protective gas as a carrier gas, preserving the temperature for reacting for 6-12 hours, and cooling to the room temperature of 20-25 ℃ along with the furnace after the reaction is finished.

5. The method for periodically increasing the discharge voltage of fluorocarbon through graphene destruction according to claim 4, wherein in the step 2, the inert shielding gas is nitrogen, helium or argon.

6. The method according to claim 4, wherein in the step 2, the volume ratio of the fluorine gas to the hydrogen gas in the mixed gas is (1-2): 1.

7. the method for periodically increasing the discharge voltage of carbon fluoride according to claim 4, wherein in the step 2, the temperature of the tube furnace is increased from 20-25 ℃ to 300-500 ℃ within 10-20 minutes.

8. The method for periodically increasing the discharge voltage of fluorocarbon by destroying graphene according to claim 4, wherein in the step 2, the temperature is raised to 380-450 ℃ and the reaction is carried out with the temperature maintained, and the reaction time is 8-10 hours.

9. The method of claim 1, wherein the discharge voltage of the obtained fluorocarbon material is controlled according to the difference of the selected bombardment current or peak power.

10. Use of a carbon fluoride material obtainable by the process according to any one of claims 1 to 9 in a lithium primary cell.

Technical Field

The invention belongs to the technical field of material science, and particularly relates to a method for periodically improving the discharge voltage of carbon fluoride by destroying graphene, in particular to a method for improving the discharge voltage of a prepared carbon fluoride material by changing the properties of a fluorocarbon covalent bond through fluorination after the periodic structure of the graphene is destroyed.

Background

The carbon fluoride material is one of the international research hotspots of high-tech, high-performance and high-benefit novel carbon-based materials, and especially the rapid development of the carbon fluoride material in the field of high-energy lithium primary batteries in recent years further promotes the application thereofBroadly, because the energy density of the fluorinated carbon (CFx) compound is highest in the solid cathode. Compared with other lithium primary batteries, the lithium/carbon fluoride battery has the advantages of large specific capacity, stable voltage, wide working temperature range, long service life and the like. Currently, the x value for most CFx compounds is about 1 for Li-CFx batteries, with a theoretical capacity of 865mAh g^-1Also in practical applications, lithium primary battery fluorides can be obtained by using graphite as the active material for panasonic electric industries.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a method for periodically improving the discharge voltage of carbon fluoride by destroying graphene, wherein the method is simple and effective to operate. The prepared carbon fluoride material has C-F ionic bond and high specific capacity, and the discharge voltage of the carbon fluoride material is higher than that of a commercial fluorinated graphene material.

The technical purpose of the invention is realized by the following technical scheme.

A method for periodically improving the discharge voltage of carbon fluoride by destroying graphene comprises the following steps:

step 1, carrying out periodic structure damage on graphene by using a plasma bombardment or laser etching method;

the graphene has a periodic structure, and the periodic structure of the graphene is destroyed at the molecular level through plasma bombardment or laser etching, so that the purpose of improving the discharge voltage of the graphene is achieved. Specifically, the method comprises the following steps:

the maximum discharge voltage can be found by changing the bombardment current, the gas ionization voltage is 1000 + -50V, the ion focusing voltage is 500 + -50V, and the vacuum degree of the plasma bombardment is 10^-2Pa, the bombardment ions are argon plasma, and the bombardment current is 40-80 mA.

The laser etching can find the maximum discharge voltage by changing the peak power, the laser wavelength is 1064nm, the pulse width is 75 +/-5 ns, the repetition frequency is 1-30kHz, the spot diameter is 70 +/-5 mu m, the moving step length is 2 +/-0.1 mu m, and the peak power is 50-80 kW.

And 2, fluorinating the graphene treated in the step 1 by using fluorine gas to obtain a carbon fluoride material.

In step 2, placing the graphene processed in the step 1 in a heating zone of a tubular furnace, installing and checking the air tightness of the tubular furnace, and introducing inert protective gas (such as nitrogen, helium or argon) into the tube to remove air in the tubular furnace; raising the temperature to 300-500 ℃, preferably 380-450 ℃, vacuumizing, introducing a mixed gas of fluorine gas and hydrogen gas, taking an inert protective gas (such as nitrogen, helium or argon) as a carrier gas, preserving the temperature for reacting for 6-12 hours, preferably 8-10 hours, cooling to room temperature of 20-25 ℃ along with the furnace after the reaction is finished, and taking out to obtain the carbon fluoride material.

In step 2, in the mixed gas of fluorine gas and hydrogen gas, the volume ratio of the two is (1-2): 1.

in step 2, the tube furnace is raised from room temperature of 20-25 ℃ to 300-500 ℃ in 10-20 minutes.

In the invention, the discharge voltage of the graphene is improved by destroying the periodic structure of the graphene on a molecular level for the first time. Due to the layered porous non-periodic structure, the structure is easily disturbed or even destroyed during the fluorination process. The C-F bond formed may be in the form of a terminal chain and attached-CF groups, rather than an infinite-CF array, resulting in a C-F bond in this region¹⁹The occurrence of F isotropic chemical shifts therein designates the semiionic C-F bond. Thus, the special fluorocarbon structure in fluoro-graphene (CFx) enables compatibility of high specific capacity and discharge potential, and unlike the expensive nanostructured carbon with low yield, the low cost of graphene ensures the productivity of such CFx. The excellent energy density of CFx can possibly replace commercial graphene fluoride, and the development of a high-performance lithium primary battery, namely the carbon fluoride material obtained according to the technical scheme of the invention and the application of the carbon fluoride material in a lithium (primary) battery are expected.

The method has the advantages of simple operation, low cost, high yield, simple post-treatment and low preparation cost, and the discharge voltage of the carbon fluoride is periodically increased by destroying the graphene, so that the discharge voltage is regulated and controlled. The resulting fluorocarbon material will have a discharge voltage of 2.88-3.20V depending on the selected bombardment current or peak power.

Drawings

Fig. 1 is a TEM photograph of raw materials without destroying the periodicity of graphene.

Fig. 2 is an electron diffraction pattern image of graphene periodicity that was not destroyed by the raw material.

Fig. 3 is a TEM photograph of graphene with destroyed periodicity in example 1.

Fig. 4 is an electron diffraction pattern image of example 1 in which the periodicity of graphene has been destroyed.

FIG. 5 is a structure characterization chart by MASNMR of carbon fluoride prepared in example 1.

FIG. 6 is a structure characterization chart by MASNMR of carbon fluoride prepared in example 2.

Fig. 7 is a graph of carbon fluoride discharge produced from untreated graphene.

Figure 8 is a graph of the carbon fluoride discharge prepared from example 1.

Figure 9 is a graph of the carbon fluoride discharge prepared from example 2.

Detailed Description

The technical solution of the present invention is explained below by specific examples. The various carbon sources used in the examples are commercially available products that can be used.

Example 1

1) Bombarding graphene by using argon plasma, wherein the gas ionization voltage for bombarding the glass substrate by the plasma is 1000V, the ion focusing voltage is 500V, and the vacuum degree for bombarding by the plasma is 10^-2pa, bombardment current 40 mA.

2) And (3) placing the graphene subjected to plasma bombardment into a heating area of the tubular furnace, installing and checking the air tightness of the tubular furnace, and introducing sufficient argon into the tube to remove air in the tubular furnace.

3) The tube furnace is heated from room temperature to 400 ℃ within 20 minutes, the tube furnace is vacuumized after the temperature reaches the set temperature, and mixed gas of fluorine gas and hydrogen gas is introduced into the tube, wherein the volume ratio is 1:1, and the mixed gas takes argon gas as carrier gas.

4) Keeping the reaction time for 8 hours, and taking out the furnace hearth after the reaction is finished and the temperature is reduced to room temperature to obtain the product.

5) The resulting product was subjected to a discharge test at a discharge voltage of 3.02V.

Example 2

1) Bombarding with argon plasma, wherein the gas ionization voltage for bombarding the glass substrate with the plasma is 1000V, the ion focusing voltage is 500V, and the vacuum degree for bombarding with the plasma is 10^-2pa, bombardment current 60 mA.

2) And (3) placing the graphene subjected to plasma bombardment into a heating area of the tubular furnace, installing and checking the air tightness of the tubular furnace, and introducing sufficient argon into the tube to remove air in the tubular furnace.

3) The temperature of the tube furnace is increased from room temperature to 450 ℃ within 20 minutes, the tube furnace is vacuumized after the temperature reaches the set temperature, and mixed gas of fluorine gas and hydrogen gas is introduced into the tube, wherein the volume ratio is 1:1, and argon is used as carrier gas of the mixed gas.

4) Keeping the reaction time for 10 hours, and taking out the furnace hearth after the reaction is finished and the temperature is reduced to room temperature to obtain the product.

5) The resulting product was subjected to a discharge test at a discharge voltage of 3.18V.

Example 3

1) Bombarding with argon plasma, wherein the gas ionization voltage for bombarding the glass substrate with the plasma is 1000V, the ion focusing voltage is 500V, and the vacuum degree for bombarding with the plasma is 10^-2pa, bombardment current 80 mA.

2) And (3) placing the graphene subjected to plasma bombardment into a heating area of the tubular furnace, installing and checking the air tightness of the tubular furnace, and introducing sufficient argon into the tube to remove air in the tubular furnace.

3) The tube furnace is heated from room temperature to 400 ℃ within 10 minutes, the tube furnace is vacuumized after the temperature reaches the set temperature, and mixed gas of fluorine gas and hydrogen gas is introduced into the tube, wherein the volume ratio is 1:1, and the mixed gas takes argon gas as carrier gas.

4) Keeping the reaction time for 15 hours, and taking out the furnace hearth after the reaction is finished and the temperature is reduced to room temperature to obtain the product.

5) The resulting product was subjected to a discharge test at a discharge voltage of 3.10V.

Example 4

1) By using a laser etching method, the laser wavelength is 1064nm, the pulse width is 75ns, the repetition frequency is 1-30kHz, the spot diameter is 70 μm, the moving step length is 2 μm, and the peak power is 50 kW.

2) And (3) placing the graphene subjected to plasma bombardment into a heating area of the tubular furnace, installing and checking the air tightness of the tubular furnace, and introducing sufficient argon into the tube to remove air in the tubular furnace.

3) The temperature of the tube furnace is increased from room temperature to 380 ℃ within 15 minutes, the tube furnace is vacuumized after the temperature reaches the set temperature, and mixed gas of fluorine gas and hydrogen gas is introduced into the tube, wherein the volume ratio is 1:1, and argon is used as carrier gas of the mixed gas.

4) Keeping the reaction time for 10 hours, and taking out the furnace hearth after the reaction is finished and the temperature is reduced to room temperature to obtain the product.

5) The resulting product was subjected to a discharge test at a discharge voltage of 2.98V.

Example 5

1) By using a laser etching method, the laser wavelength is 1064nm, the pulse width is 75ns, the repetition frequency is 1-30kHz, the spot diameter is 70 μm, the moving step length is 2 μm, and the peak power is 80 kW.

2) And (3) placing the graphene subjected to plasma bombardment into a heating area of the tubular furnace, installing and checking the air tightness of the tubular furnace, and introducing sufficient argon into the tube to remove air in the tubular furnace.

3) The tube furnace is heated from room temperature to 400 ℃ within 20 minutes, the tube furnace is vacuumized after the temperature reaches the set temperature, and mixed gas of fluorine gas and hydrogen gas is introduced into the tube, wherein the volume ratio is 1:1, and the mixed gas takes argon gas as carrier gas.

4) Keeping the reaction time for 8 hours, and taking out the furnace hearth after the reaction is finished and the temperature is reduced to room temperature to obtain the product.

5) The obtained product was subjected to a discharge test at a discharge voltage of 3.01V.

Fig. 1 and fig. 2 are TEM and electron diffraction pattern images of graphene before periodic destruction, and it can be seen from fig. 1 that the periodic undamaged graphene has fewer stripes, and the whole graphene surface is clear, while the electron diffraction pattern of fig. 2 can clearly see the lattice image of the periodic single crystal of graphene. Fig. 3 and 4 are TEM and electron diffraction pattern images of the periodically destroyed graphene as in example 1, the periodically destroyed graphene shows a large number of stripes and wrinkles, the graphene surface becomes rough, and it is apparent from the electron diffraction pattern of fig. 4 that there is no lattice image of the destroyed graphene periodic structure. FIGS. 5 and 6 are structural characterization graphs of Magic Angle Spin Nuclear Magnetic Resonance (MASNMR) structures of periodically destroyed graphene after fluorination, and it can be seen from the graphs that the shift peak of F is mainly-140 ppm and covers the range from-200 ppm to-50 ppm, which exactly correspond to the result of fluorinated graphene, indicating that the periodically destroyed graphene has been successfully fluorinated.

FIG. 7 is a fluorinated graphene product formed by fluorination of untreated graphene, with a median discharge voltage of 2.6V and a maximum specific capacity of 647mAh g^-1FIGS. 8 and 9 show the fluorinated graphene products formed by the fluorination of graphene treated as in examples 1 and 2, the median discharge voltages were 3.02V and 3.18V, and the maximum specific capacities were 897mAh g^-1And 902mAh g^-1. Through tests, the discharge voltage and the maximum specific capacity of the fluorinated graphene products prepared in the other examples are higher than those of the fluorinated graphene product formed by fluorination of untreated graphene, which indicates that the value voltage and the maximum specific capacity of the fluorinated graphene product formed by fluorination of treated graphene are greatly improved.

According to the invention, the process parameters are adjusted, and the discharge voltage of the prepared fluorinated graphene can reach 2.88-3.20V through testing, which is higher than that of a fluorinated graphene product formed by untreated graphene fluorination, so that the performance of the corresponding carbon fluoride material is obviously enhanced after the periodic structure of the graphene is damaged by a plasma bombardment or laser etching method. The invention has been described in an illustrative manner, and it is to be understood that any simple variations, modifications or other equivalent changes which can be made by one skilled in the art without departing from the spirit of the invention fall within the scope of the invention.