Carbon fluoride material based on metal-based ionic liquid modification and preparation method thereof

Abstract

The invention discloses a preparation method of a carbon fluoride material based on metal-based ionic liquid modification, which comprises the following steps: heating an ionic liquid to 30-100 DEG C in an inert atmosphere, then adding a metal salt, uniformly stirring to obtain a metal-based ionic liquid, dispersing the metal-based ionic liquid into an organic solvent, then adding carbon fluoride, uniformly stirring, carrying out suction filtration on the mixed solution, and drying to obtain the carbon fluoride material based on metal-based ionic liquid modification. And finally, calcining at 300-450 DEG C for 0-12 hours to obtain the catalyst. The method is simple in preparation process and low in cost, large-scale production can be achieved, the prepared carbon fluoride material has good rate capability and discharge capacity when serving as a lithium / carbon fluoride primary battery positive electrode material, and the problems that an existing lithium / carbon fluoride primary battery is poor in rate capability and poor in discharge capacity are solved. And the problems of low power density, voltage lag under high-rate discharge and low discharge capacity are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium / carbon fluoride primary batteries, and in particular relates to a carbon fluoride material modified by a metal-based ionic liquid and a preparation method thereof. Background Art

[0002] Lithium / carbon fluoride battery is the primary battery with the highest theoretical mass energy density, with a mass energy density of up to 2160Wh / kg. Compared with other primary batteries, lithium / carbon fluoride primary batteries have the advantages of stable voltage platform, high specific capacity, low self-discharge rate, and long service life. Therefore, they are widely used in medical and military fields. However, due to the strong covalent nature of the CF bond of carbon fluoride, its conductivity is poor, resulting in poor rate performance and low power density of carbon fluoride materials. At the same time, the LiF produced by the special fluorination mechanism of lithium / carbon fluoride primary batteries during discharge will cause the battery to respond slowly and have voltage lag. Summary of the invention

[0003] The purpose of the present invention is to solve the problems of poor rate performance, low power density, voltage hysteresis and low discharge capacity of lithium / carbon fluoride primary batteries under high rate discharge, and provide a metal-based ionic liquid modified carbon fluoride material and a preparation method thereof.

[0004] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0005] A method for preparing a fluorinated carbon material modified by a metal-based ionic liquid comprises the following steps:

[0006] (1) heating the ionic liquid to 30-100° C. under an inert atmosphere, then adding a metal salt and stirring evenly to obtain a metal-based ionic liquid;

[0007] (2) The metal-based ionic liquid is dispersed in an organic solvent, and then carbon fluoride is added and stirred evenly to obtain a mixed solution, which is then filtered and dried, and finally calcined to obtain a carbon fluoride material modified by the metal-based ionic liquid.

[0008] In step (1), the ionic liquid is an imidazole ionic liquid, a pyridine ionic liquid or a quaternary ammonium salt ionic liquid.

[0009] In step (2), the calcination temperature is 300-450° C. and the calcination time is 0-12 h.

[0010] Furthermore, in step (1), the metal salt is selected from iron salt, copper salt, aluminum salt, zinc salt, manganese salt or calcium salt.

[0011] Furthermore, in step (1), the molar ratio of the ionic liquid to the metal salt is 1:(0.5-2).

[0012] Furthermore, in step (2), the organic solvent is ethanol, acetone or chloroform.

[0013] Furthermore, in step (2), the volume ratio of the metal-based ionic liquid to the organic solvent is 1:(1-20).

[0014] Furthermore, in step (2), the mass ratio of the metal-based ionic liquid to carbon fluoride is (1-10):5.

[0015] Furthermore, in step (2), the drying temperature is 60-80° C. and the drying time is 24-36 hours.

[0016] The fluorinated carbon material modified by metal-based ionic liquid is prepared by the above method.

[0017] A lithium / carbon fluoride battery, wherein the positive electrode of the lithium / carbon fluoride battery comprises the above-mentioned carbon fluoride material modified by metal-based ionic liquid.

[0018] Beneficial effects of the present invention:

[0019] The invention discloses a method for preparing a fluorinated carbon material modified by a metal-based ionic liquid. The method adopts a surface-compounding method to carry out interface modification on the fluorinated carbon. The method has a simple preparation process, low cost and can be mass-produced. Based on the good ionic conductivity and wide electrochemical window of the metal-based ionic liquid or based on the conductive network of metal oxide and carbon generated after the metal-based ionic liquid is calcined, the prepared fluorinated carbon material has good rate performance and discharge capacity when used as a positive electrode material for a lithium / carbon fluoride primary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a discharge curve diagram of a lithium / carbon fluoride primary battery prepared using the carbon fluoride material of Comparative Example 1;

[0021] Figure 2 For the CF of Example 1 x @BmimFeCl 4 -5 Discharge curve of the prepared lithium / carbon fluoride primary battery;

[0022] Figure 3 For the CF of Example 2 x @BmimFeCl 4 -10 Discharge curve of lithium / carbon fluoride primary battery prepared;

[0023] Figure 4 For the CF of Example 3 x @BmimFeCl 4 -20 Discharge curve of lithium / carbon fluoride primary battery prepared;

[0024] Figure 5 For the CF of Example 4 x @Fe 2 O 3 / C-5 prepared lithium / carbon fluoride primary battery discharge curve;

[0025] Figure 6 For the CF of Example 5 x @Fe 2 O 3 Discharge curve of lithium / carbon fluoride primary battery prepared by / C-10;

[0026] Figure 7 For the CF of Example 6 x @Fe 2 O 3 Discharge curve of lithium / carbon fluoride primary battery prepared by / C-20. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] A method for preparing a fluorinated carbon material modified by a metal-based ionic liquid comprises the following steps:

[0030] (1) In a glove box filled with argon atmosphere, 1.747 g of BmimCl (1-butyl-3-methylimidazolium chloride) was heated to 70 °C, and then a total of 1.946 g of anhydrous FeCl was added in three portions. 3 , and magnetically stirred for 24 h to obtain the metal-based ionic liquid BmimFeCl 4 ;

[0031] (2) Metal-based ionic liquid (BmimFeCl 4 ) were dispersed in anhydrous ethanol at a volume ratio of 1:19, and then 0.5 g of carbon fluoride was added and magnetically stirred for 12 h to obtain a mixed solution, which was then filtered and dried in a vacuum oven at 70 ° C for 12 h to obtain BmimFeCl 4 Modified fluorinated carbon, denoted as CF x @BmimFeCl 4 -5.

[0032] Example 2

[0033] A method for preparing a fluorinated carbon material modified by a metal-based ionic liquid comprises the following steps:

[0034] (1) In a glove box filled with argon atmosphere, 1.747 g of BmimCl (1-butyl-3-methylimidazolium chloride) was heated to 70 °C, and then a total of 1.946 g of anhydrous FeCl was added in three portions. 3 , and magnetically stirred for 24 h to obtain the metal-based ionic liquid BmimFeCl 4 ;

[0035] (2) Metal-based ionic liquid (BmimFeCl 4 ) was dispersed in an ethanol solution at a volume ratio of 1:9, and then 0.5 g of carbon fluoride was added and magnetically stirred for 12 h to obtain a mixed solution, which was then filtered and dried in a vacuum oven at 70 ° C for 12 h to obtain BmimFeCl 4 Modified fluorinated carbon, denoted as CF x @BmimFeCl 4 -10.

[0036] Example 3

[0037] A method for preparing a fluorinated carbon material modified by a metal-based ionic liquid comprises the following steps:

[0038] (1) In a glove box filled with argon atmosphere, 1.747 g of BmimCl (1-butyl-3-methylimidazolium chloride) was heated to 70 °C, and then a total of 1.946 g of anhydrous FeCl was added in three portions. 3 , and magnetically stirred for 24 h to obtain the metal-based ionic liquid BmimFeCl 4 ;

[0039] (2) Metal-based ionic liquid (BmimFeCl 4 ) were dispersed in an ethanol solution at a volume ratio of 1:4, and then 0.5 g of carbon fluoride was added and magnetically stirred for 12 h to obtain a mixed solution, which was then filtered and dried in a vacuum oven at 70 ° C for 12 h to obtain BmimFeCl 4 Modified fluorinated carbon, denoted as CF x @BmimFeCl 4 -20.

[0040] Example 4

[0041] A method for preparing a fluorinated carbon material modified by a metal-based ionic liquid comprises the following steps:

[0042] (1) In a glove box filled with argon atmosphere, 1.747 g of BmimCl (1-butyl-3-methylimidazolium chloride) was heated to 70 °C, and then a total of 1.946 g of anhydrous FeCl was added in three portions. 3 , and magnetically stirred for 24 h to obtain the metal-based ionic liquid BmimFeCl4 ;

[0043] (2) Metal-based ionic liquid (BmimFeCl 4 ) were dispersed in an ethanol solution at a volume ratio of 1:19, and then 0.5 g of carbon fluoride was added and magnetically stirred for 12 h to obtain a mixed solution, which was then filtered and dried in a vacuum oven at 70 ° C for 12 h, and finally heated in O 2 The calcination was carried out under the atmosphere for 6 hours at a temperature of 350°C to obtain Fe 2 O 3 / C modified fluorinated carbon, denoted as CF x @Fe 2 O 3 / C-5.

[0044] Example 5

[0045] A method for preparing a fluorinated carbon material modified by a metal-based ionic liquid comprises the following steps:

[0046] (1) In a glove box filled with argon atmosphere, 1.747 g of BmimCl (1-butyl-3-methylimidazolium chloride) was heated to 70 °C, and then a total of 1.946 g of anhydrous FeCl was added in three portions. 3 , and magnetically stirred for 24 h to obtain the metal-based ionic liquid BmimFeCl 4 ;

[0047] (2) Metal-based ionic liquid (BmimFeCl 4 ) were dispersed in an ethanol solution at a volume ratio of 1:9, and then 0.5 g of carbon fluoride was added and magnetically stirred for 12 h to obtain a mixed solution, which was then filtered and dried in a vacuum oven at 70 ° C for 12 h, and finally heated in O 2 The calcination was carried out under the atmosphere for 6 hours at a temperature of 350°C to obtain Fe 2 O 3 / C modified fluorinated carbon, denoted as CF x @Fe 2 O 3 / C-10.

[0048] Example 6

[0049] A method for preparing a fluorinated carbon material modified by a metal-based ionic liquid comprises the following steps:

[0050] (1) In a glove box filled with argon atmosphere, 1.747 g of BmimCl (1-butyl-3-methylimidazolium chloride) was heated to 70 °C, and then a total of 1.946 g of anhydrous FeCl was added in three portions. 3, and magnetically stirred for 24 h to obtain the metal-based ionic liquid BmimFeCl 4 ;

[0051] (2) Metal-based ionic liquid (BmimFeCl 4 ) were dispersed in an ethanol solution at a volume ratio of 1:4, and then 0.5 g of carbon fluoride was added and magnetically stirred for 12 h to obtain a mixed solution, which was then filtered and dried in a vacuum oven at 70 ° C for 12 h, and finally heated to 0 2 The calcination was carried out under the atmosphere for 6 hours at a temperature of 350°C to obtain Fe 2 O 3 / C modified fluorinated carbon, denoted as CF x @Fe 2 O 3 / C-20.

[0052] Comparative Example 1

[0053] As Comparative Example 1, pristine fluorinated carbon was used.

[0054] The carbon fluoride materials prepared in Comparative Example 1 and Examples 1-6 were used to prepare lithium / carbon fluoride primary batteries:

[0055] 1) The carbon fluoride material, the conductive agent (superp) and the binder (PVDF) were ground and mixed at a mass ratio of 8:1:1 for 15 minutes, and then N-methylpyrrolidone was added to carry out degassing and mixing in a degassing machine for 30 minutes. The obtained slurry was evenly coated on an aluminum foil using a scraper with a thickness of 100 μm, and dried at 70°C for 2 hours. The slurry was cut in a drying room to obtain a carbon fluoride electrode. The electrode was placed in a sample bag and dried in a vacuum oven at 100°C for 12 hours.

[0056] 2) Preparation of button cells

[0057] In a glove box filled with argon atmosphere, LIR2032 button batteries are assembled in the order of negative electrode shell, spring sheet, stainless steel gasket, metal lithium sheet, electrolyte, diaphragm, electrolyte, carbon fluoride positive electrode sheet, and positive electrode shell.

[0058] The electrochemical performance of the button cell was tested, and the results are shown in Figure 1-Figure 7 .

[0059] Figure 1 is a discharge curve diagram of a lithium / carbon fluoride primary battery prepared using the carbon fluoride material of Comparative Example 1, Figure 2 For the CF of Example 1 x @BmimFeCl 4 -5 The discharge curve of the lithium / carbon fluoride primary battery prepared, Figure 3 For the CF of Example 2x @BmimFeCl 4 -10 The discharge curve of the lithium / carbon fluoride primary battery prepared, Figure 4 For the CF of Example 3 x @BmimFeCl 4 -20 The discharge curve of the lithium / carbon fluoride primary battery prepared, Figure 5 For the CF of Example 4 x @Fe 2 O 3 Discharge curve of lithium / carbon fluoride primary battery prepared by / C-5, Figure 6 For the CF of Example 5 x @Fe 2 O 3 Discharge curve of lithium / carbon fluoride primary battery prepared by / C-10, Figure 7 For the CF of Example 6 x @Fe 2 O 3 The discharge curve of the lithium / carbon fluoride primary battery prepared by / C-20 is Figure 1 It can be seen that the original carbon fluoride is difficult to discharge effectively at a discharge rate of 2C, and (from Figure 2-4 It can be seen that) after different volume ratios of BmimFeCl 4 The modified carbon fluoride can be effectively discharged at a discharge rate of 2C and has a stable voltage platform, and can even be discharged at a higher rate. Figure 2 CF x @BmimFeCl 4 -5 can discharge at a maximum rate of 4C and has a specific capacity of more than 200mAh / g. Figure 4 CF x @BmimFeCl 4 -20 can discharge at a maximum rate of 6C and has a specific capacity of 156.5mAh / g. Figure 3 As you can see, CF x @BmimFeCl 4 -10 can be discharged at a high rate of up to 8C, and has a specific capacity of nearly 350mAh / g, indicating that after the interface modification of the metal-based ionic liquid, the rate performance and discharge capacity of the carbon fluoride material are effectively improved.

[0060] Similarly, after calcination, the materials can be effectively discharged at a discharge rate far higher than 2C. Figure 5 For CF x @Fe 2 O 3 / C-5. It can be seen from the figure that it can be discharged at a maximum of 8C and has a specific capacity of nearly 150mAh / g. Figure 7 For CF x @Fe 2 O 3 / C-20, it can be seen from the figure that it can be discharged under the condition of up to 10C, and can effectively output a specific capacity of 257mAh / g. x @Fe 2 O 3 / C-10, from Figure 6 It can be seen that the calcined sample can be discharged at a rate of up to 14C, with a specific capacity of nearly 400mAh / g and a stable discharge platform, indicating that the conductive network of metal oxide and carbon formed after calcination of the fluorinated carbon material modified by metal-based ionic liquid can greatly improve the rate performance of the fluorinated carbon.

[0061] Although the preferred embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments, which are merely illustrative and not restrictive. Under the guidance of the present invention, a person skilled in the art can make many forms without departing from the scope of protection of the present invention and the claims. All of these fall within the scope of protection of the present invention.

Claims

1. A method for preparing a fluorinated carbon material modified by a metal-based ionic liquid, characterized in that: The steps include: (1) heating the ionic liquid to 30-100° C. under an inert atmosphere, then adding a metal salt and stirring evenly to obtain a metal-based ionic liquid; (2) dispersing the metal-based ionic liquid into an organic solvent, then adding carbon fluoride, stirring evenly to obtain a mixed solution, filtering the mixed solution, drying it, and finally calcining it to obtain a carbon fluoride material modified by the metal-based ionic liquid; In step (1), the ionic liquid is an imidazole ionic liquid, a pyridine ionic liquid or a quaternary ammonium salt ionic liquid; In step (2), the calcination temperature is 300-450° C. and the calcination time is 0-12 h.

2. The method for preparing a fluorinated carbon material modified by a metal-based ionic liquid according to claim 1, characterized in that: In step (1), the metal salt is selected from iron salt, copper salt, aluminum salt, zinc salt, manganese salt or calcium salt.

3. The method for preparing a fluorinated carbon material modified by a metal-based ionic liquid according to claim 1, characterized in that: In step (1), the molar ratio of the ionic liquid to the metal salt is 1:(0.5-2).

4. The method for preparing a fluorinated carbon material modified by a metal-based ionic liquid according to claim 1, characterized in that: In step (2), the organic solvent is ethanol, acetone or chloroform.

5. The method for preparing a fluorinated carbon material modified by a metal-based ionic liquid according to claim 1, characterized in that: In step (2), the volume ratio of the metal-based ionic liquid to the organic solvent is 1:(1-20).

6. The method for preparing a fluorinated carbon material modified by a metal-based ionic liquid according to claim 1, characterized in that: In step (2), the mass ratio of the metal-based ionic liquid to carbon fluoride is (1-10):

5.

7. The method for preparing a fluorinated carbon material modified by a metal-based ionic liquid according to claims 1 to 6, characterized in that: In step (2), the drying temperature is 60-80°C and the drying time is 24-36 hours.

8. A fluorinated carbon material modified by a metal-based ionic liquid prepared by the method according to any one of claims 1 to 7.

9. A lithium / carbon fluoride battery, characterized in that: The positive electrode of the lithium / carbon fluoride battery comprises the carbon fluoride material modified by the metal-based ionic liquid according to claim 8.

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