High discharge voltage carbon fluoride, and preparation method and application thereof
By forming fluorocarbon bonds through low-temperature fluorination of hierarchical porous amorphous carbon, the problem of insufficient discharge voltage in fluorinated carbon materials was solved, and the preparation of fluorinated carbon materials with high discharge voltage was realized, which is suitable for high-energy lithium primary batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING UNIV OF CHEM TECH
- Filing Date
- 2025-07-17
- Publication Date
- 2026-05-08
AI Technical Summary
The discharge voltage of existing fluorinated carbon materials is far lower than their thermodynamic theoretical value. Especially in the high-temperature gas-phase fluorination preparation process, due to the sp3 hybridization of carbon atoms and fluorine atoms, the insulating properties of covalent compounds are caused by the need to consume a lot of energy to break the fluorine-carbon bond. The fluorination temperature in the existing methods needs to be further reduced and the discharge voltage can only be increased to a limited extent.
Amorphous carbon with a hierarchical porous structure and a specific surface area of not less than 1000 m2/g is subjected to a low-temperature fluorination reaction in a fluorine-containing atmosphere. The fluorination temperature is 20~200℃, forming fluorine-carbon bonds with sp2 conjugated conductive structure. Combined with the porous network structure of the carbon raw material, it promotes charge transfer inside the electrode and reduces bond energy.
The discharge voltage of fluorocarbon materials has been increased to 3.33~3.52V (vs. Li/Li+), which improves the chemical energy utilization of the material, reduces heat during the discharge process, and alleviates the initial polarization voltage, making it suitable for fields with high power requirements such as drones.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of primary battery technology, specifically relating to a high-discharge-voltage fluorinated carbon, its preparation method, and its application. Background Technology
[0002] In the field of energy materials today, fluorinated carbon materials are a highly regarded material. Due to their high theoretical energy density, they have shown great application potential in many fields. In particular, as a cathode material in lithium / fluorinated carbon batteries, they are regarded as the key material of the "ultimate primary lithium battery" and have important application prospects in fields with extremely high battery performance requirements, such as aerospace, deep-sea exploration, and medical implant devices.
[0003] Although fluorinated carbon materials play a crucial role in high-energy lithium primary batteries, their potential remains to be further explored, especially the issue of their discharge voltage being far lower than the thermodynamic theoretical value, which urgently needs to be addressed. According to the electrode reaction equation, the theoretical discharge voltage of a lithium / fluorinated carbon battery should be ~4.55V (vs. Li / Li). + However, the discharge voltage of commonly used fluorinated graphite is only 2.5~2.6V (vs. Li / Li). + This is mainly because during the high-temperature (450~600℃) gas-phase fluorination process to prepare high fluorine-to-carbon ratio (F / C) fluorinated graphite, each carbon atom forms a chemical bond with a fluorine atom, causing the hybridization state of the carbon atom to change from sp... 2 Transform into sp 3 Therefore, the resulting fluorocarbon bond exhibits typical insulating properties of covalent compounds. Furthermore, the fluorocarbon bond has the highest bond energy among all covalent single bonds. Consequently, a large amount of energy is required to break the fluorocarbon bond during discharge, and it forms lithium fluoride with lithium ions, causing the actual discharge voltage to deviate from its thermodynamic theoretical value.
[0004] Existing technologies have successfully improved the discharge voltage of fluorinated carbon by optimizing the selection of carbon raw materials and improving the fluorination process. Typically, carbon nanomaterials with special nanomorphologies, such as graphene, carbon nanospheres, or carbon nanofibers, are used, combined with optimized fluorination processes. For example, nitrogen trifluoride (NF3), which can decompose at high temperatures to produce fluorine atoms, is used as the fluorine source, while the temperature is lowered to 300-400℃. This increases the discharge voltage of the prepared fluorinated carbon nanomaterials to 3.0-3.2V (vs. Li / Li). + This is mainly attributed to the unique spatial structure of carbon nanomaterials and the appropriately reduced fluorine-to-carbon ratio, which leads to the formation of fluorine-carbon half-ionic bonds with lower bond energies. This reduces the energy required to break the fluorine-carbon bonds during discharge, ultimately increasing the discharge voltage of fluorinated carbon. However, the fluorination temperature in the above method needs to be further reduced, and the discharge voltage still needs to be further increased. Summary of the Invention
[0005] The purpose of this invention is to provide a high discharge voltage fluorinated carbon, its preparation method, and its application. The method provided by this invention has a low fluorination temperature and the resulting fluorinated carbon has a higher discharge voltage.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] This invention provides a method for preparing high-discharge-voltage fluorinated carbon, comprising the following steps:
[0008] Amorphous carbon is fluorinated in a fluorine-containing atmosphere to obtain the high discharge voltage fluorinated carbon.
[0009] The amorphous carbon has a hierarchical porous structure;
[0010] The specific surface area of the amorphous carbon is not less than 1000 m². 2 / g;
[0011] The fluorination temperature is 20~200℃.
[0012] Preferably, the specific surface area of the amorphous carbon is 1000~3500 m². 2 / g.
[0013] Preferably, the fluorination time is 12-36 hours.
[0014] Preferably, the fluorination pressure is 0.01~0.5MPa.
[0015] Preferably, the fluorine-containing atmosphere includes fluorine gas and a protective gas, wherein the protective gas includes at least one of nitrogen, argon, and helium;
[0016] The volume ratio of fluorine gas in the fluorine-containing atmosphere is 10-30%.
[0017] The present invention also provides high discharge voltage fluorinated carbon prepared by the preparation method described in the above technical solution.
[0018] Preferably, the high discharge voltage fluorinated carbon comprises 50-70% carbon, 20-40% fluorine and 5-20% oxygen, based on atomic percentage.
[0019] Preferably, the specific surface area of the high-discharge-voltage fluorinated carbon is not less than 300 m². 2 / g.
[0020] The present invention also provides the application of high discharge voltage fluorinated carbon as a positive electrode in primary batteries as described above.
[0021] This invention provides a method for preparing high-discharge-voltage fluorinated carbon. This invention uses materials with a specific surface area of not less than 1000 m². 2Using amorphous carbon with a hierarchical porous structure ( / g) as the carbon raw material alters the temperature required for the fluorination reaction. Its abundant pore structure defects and amorphous properties facilitate fluorination reactions at low temperatures. Low-temperature fluorination not only effectively preserves the sp(s) of the carbon raw material... 2 The conjugated conductive structure can also form fluorocarbon bonds at the edges of pore structure defects, interacting with adjacent sp atoms. 2 Hybridized carbon atoms further reduce bond energy through p-π hyperconjugation. Combined with the porous network structure of the carbon raw material itself, this promotes charge transfer within the electrode. The combined effect of these multiple factors ultimately increases the discharge voltage of the fluorinated carbon material to 3.33~3.52V (vs. Li / Li). + The increased discharge voltage of fluorocarbon not only improves the chemical energy utilization of the material and reduces heat during the discharge process, but also the conductive fluorocarbon semi-ionic bonds can alleviate the polarization voltage at the beginning of the discharge, making it a promising candidate for applications in high-power fields such as drones. Attached Figure Description
[0022] Figure 1 The N2 isotherm adsorption curves of amorphous carbon used in Examples 1-3 are shown.
[0023] Figure 2 The N2 isotherm adsorption curve of fluorinated carbon obtained in Example 1;
[0024] Figure 3 The X-ray photoelectron spectrum of fluorinated carbon obtained in Example 1 is shown below.
[0025] Figure 4 The constant current discharge curve of the coin cell obtained by fluorinated carbon assembly in Example 1;
[0026] Figure 5 The N2 isotherm adsorption curve of fluorinated carbon obtained in Example 2;
[0027] Figure 6 The constant current discharge curve of the coin cell obtained by fluorinated carbon assembly in Example 2;
[0028] Figure 7 The N2 isotherm adsorption curve of fluorinated carbon obtained in Example 3;
[0029] Figure 8 The constant current discharge curve of the coin cell assembled with fluorinated carbon in Example 3.
[0030] Figure 9 The N2 isotherm adsorption curves of amorphous carbon used in Examples 4 and 5 are shown.
[0031] Figure 10 The N2 isotherm adsorption curve of fluorinated carbon obtained in Exercise 4;
[0032] Figure 11 The X-ray photoelectron spectrum of fluorinated carbon obtained in Example 4 is shown below.
[0033] Figure 12 The constant current discharge curve of the coin cell obtained by carbon fluoride assembly in Example 4.
[0034] Figure 13 The N2 isotherm adsorption curve of fluorinated carbon obtained in Example 5;
[0035] Figure 14 The constant current discharge curve of the coin cell obtained by fluorinated carbon assembly in Example 5;
[0036] Figure 15 The N2 isotherm adsorption curve of amorphous carbon used in Example 6;
[0037] Figure 16 N2 isothermal adsorption curves of fluorinated carbon obtained in Exercise 6;
[0038] Figure 17 The X-ray photoelectron spectrum of fluorinated carbon obtained in Example 6 is shown below.
[0039] Figure 18 The constant current discharge curve of the coin cell obtained by fluorinated carbon assembly in Example 6;
[0040] Figure 19 The constant current discharge curve of the coin cell assembled from fluorinated graphite in Comparative Example 1.
[0041] Figure 20 The constant current discharge curve of the coin cell assembled from fluorinated porous carbon in Comparative Example 2 is shown. Detailed Implementation
[0042] This invention provides a method for preparing high-discharge-voltage fluorinated carbon, comprising the following steps:
[0043] Amorphous carbon is fluorinated in a fluorine-containing atmosphere to obtain the high discharge voltage fluorinated carbon.
[0044] The amorphous carbon has a hierarchical porous structure;
[0045] The specific surface area of the amorphous carbon is not less than 1000 m². 2 / g;
[0046] The fluorination temperature is 20~200℃.
[0047] In this invention, the specific surface area of the amorphous carbon is preferably 1000~3500 m². 2 / g. In this invention, the amorphous carbon is preferably purchased from Foshan Perls Carbon Materials Technology Co., Ltd., and the models are UltraSorb-1, UltraSorb-2, or PC-2. In a specific embodiment of this invention, the amorphous carbon of model UltraSorb-1 has a specific surface area of 2602 m². 2 / g; the specific surface area of amorphous carbon of type UltraSorb-2 is 2331m². 2 / g; the specific surface area of amorphous carbon of type PC-2 is 1061 m². 2 / g.
[0048] In this invention, the fluorine-containing atmosphere preferably includes fluorine gas and a protective gas, and the protective gas preferably includes at least one of nitrogen, argon and helium; the volume ratio of fluorine gas in the fluorine-containing atmosphere is preferably 10-30%, specifically 10%, 15%, 20%, 25% and 30%.
[0049] In this invention, the fluorination temperature is 20~200℃, specifically 20℃, 50℃, 100℃, 150℃, or 200℃; the fluorination time is preferably 12~36h, specifically 12h, 18h, 24h, 30h, or 36h. In this invention, the fluorination pressure is preferably 0.01~0.5MPa, specifically 0.01MPa, 0.05MPa, 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, or 0.5MPa; the fluorination is preferably carried out in a nickel reactor.
[0050] This invention also provides high discharge voltage fluorinated carbon prepared by the preparation method described in the above technical solution. In this invention, the high discharge voltage fluorinated carbon preferably comprises 50-70% carbon, 20-40% fluorine, and 5-20% oxygen, based on atomic percentage.
[0051] In this invention, the specific surface area of the high-discharge-voltage fluorinated carbon is preferably not less than 300 m². 2 / g, further preferably not less than 542m 2 / g, more preferably 542~1035m 2 / g. In this invention, the discharge voltage of the high-discharge-voltage fluorinated carbon is 3.33~3.52V (vs. Li / Li). + ).
[0052] The present invention also provides the application of high discharge voltage fluorinated carbon as a positive electrode in primary batteries as described above.
[0053] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.
[0054] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0055] Example 1
[0056] 100g of amorphous carbon (UltraSorb-1) purchased from Foshan Perls Carbon Materials Technology Co., Ltd. was weighed and evenly spread inside the nickel reactor to ensure the fluorination reaction proceeded. The nitrogen isothermal adsorption curve of the selected amorphous carbon is shown below. Figure 1 As shown, the specific surface area measured by the BET method is 2602 m². 2 / g;
[0057] The furnace was evacuated to -0.1 MPa using a vacuum pump; a fluorine-nitrogen atmosphere (of which fluorine accounted for 30% by volume) was introduced to 0.1 MPa, and a fluorination reaction was carried out at 20°C. After fluorination for 36 hours, fluorinated carbon was obtained.
[0058] The nitrogen isotherm adsorption curve of the obtained carbon fluoride is as follows: Figure 2 As shown, the specific surface area measured by the BET method is 1035 m². 2 / g. The X-ray photoelectron spectroscopy results of the obtained fluorinated carbon are as follows: Figure 3 As shown, the atomic percentages of carbon, fluorine, and oxygen in the prepared fluorinated carbon are 67.51%, 22.25%, and 10.24%, respectively.
[0059] The preparation process of the fluorinated carbon cathode is as follows: The electrode is prepared from the above-obtained fluorinated carbon (80wt%), conductive carbon black (10wt%), sodium carboxymethyl cellulose (5wt%), and lithium polyacrylate (5wt%). The above materials are dispersed in deionized water to form a uniform slurry, which is then coated onto carbon-coated aluminum foil and vacuum dried at 120°C for 12 hours. The active material is cut into circular fluorinated carbon cathode sheets with a diameter of 12 mm and then transferred to a glove box for battery assembly.
[0060] The assembly process of the button battery is as follows: lithium metal sheet is selected as the negative electrode, lithium bis(fluorosulfonyl)imide (LiFSI) is used as the lithium salt in the electrolyte, and propylene carbonate (PC) and dimethyl ethylene glycol (DME) are used as solvents. The concentration of lithium salt in the prepared electrolyte is 1 mol / L, and the volume ratio of PC to DME is 1:1. The negative electrode shell, spring sheet, gasket, lithium metal sheet, separator, fluorinated carbon positive electrode sheet, and positive electrode shell are stacked and assembled in that order.
[0061] The assembled CR2032 coin cells were subjected to performance testing. A constant current discharge test was performed on the assembled coin cells at a current density of 10 mA / g, and the discharge curves are shown below. Figure 4 As shown, from Figure 4 It can be seen that the initial discharge voltage of the prepared fluorinated carbon is 3.52V (vs. Li / Li). + The median discharge voltage is 3.48V (vs. Li / Li). + The discharge specific capacity is 662mAh / g.
[0062] Example 2
[0063] 100g of amorphous carbon, identical to that in Example 1, was weighed and evenly spread in a nickel reactor to ensure the fluorination reaction proceeded. The furnace was evacuated to -0.1MPa using a vacuum pump. A fluorine-nitrogen atmosphere (with fluorine accounting for 20% of the volume) was introduced to 0.15MPa, and the fluorination reaction was carried out at 100°C. After fluorination for 24 hours, fluorinated carbon was obtained. The corresponding nitrogen isothermal adsorption curve is shown below. Figure 5 As shown, the specific surface area measured by the BET method is 928 m². 2 / g.
[0064] Fluorinated carbon electrodes and coin cells were prepared according to the method in Example 1, and constant current discharge tests were performed on them. The discharge curves are shown below. Figure 6 As shown, from Figure 6 It can be seen that the initial discharge voltage of the prepared fluorinated carbon is 3.50V (vs. Li / Li). + The median discharge voltage is 3.48V (vs. Li / Li). + The discharge specific capacity is 746mAh / g.
[0065] Example 3
[0066] 100g of amorphous carbon, identical to that in Example 1, was weighed and evenly spread in a nickel reactor to ensure the fluorination reaction proceeded. The furnace was evacuated to -0.1MPa using a vacuum pump. A fluorine-nitrogen atmosphere (fluorine gas accounting for 20% of the volume) was introduced to 0.015MPa, and the fluorination reaction was carried out at 200℃. After fluorination for 18 hours, fluorinated carbon was obtained. The corresponding nitrogen isotherm adsorption curve is shown below. Figure 7 As shown, the specific surface area measured by the BET method is 722 m². 2 / g.
[0067] Fluorinated carbon electrodes and coin cells were prepared according to the method in Example 1, and constant current discharge tests were performed on them. The discharge curves are shown below. Figure 8 As shown, from Figure 8 It can be seen that the initial discharge voltage of the prepared fluorinated carbon is 3.42V (vs. Li / Li). +The median discharge voltage is 3.35V (vs. Li / Li). + The discharge specific capacity is 848mAh / g.
[0068] Example 4
[0069] 100g of amorphous carbon (UltraSorb-2) purchased from Foshan Perls Carbon Materials Technology Co., Ltd. was weighed and evenly spread inside the nickel reactor to ensure the fluorination reaction proceeded. The nitrogen isothermal adsorption curve of the selected amorphous carbon is shown below. Figure 9 As shown, the specific surface area measured by the BET method is 2331 m². 2 / g;
[0070] The furnace was evacuated to -0.1 MPa using a vacuum pump; a fluorine-nitrogen atmosphere (of which fluorine accounted for 30% by volume) was introduced to 0.3 MPa, and a fluorination reaction was carried out at 20°C. After fluorination for 24 hours, fluorinated carbon was obtained.
[0071] The nitrogen isotherm adsorption curve of the obtained carbon fluoride is as follows: Figure 10 As shown, the specific surface area measured by the BET method is 975 m². 2 / g. The X-ray photoelectron spectroscopy results of the obtained fluorinated carbon are as follows: Figure 11 As shown, the atomic percentages of carbon, fluorine, and oxygen in the prepared fluorinated carbon are 62.18%, 29.93%, and 7.89%, respectively.
[0072] Fluorinated carbon electrodes and coin cells were prepared according to the method in Example 1, and constant current discharge tests were performed on them. The discharge curves are shown below. Figure 12 As shown, from Figure 12 It can be seen that the initial discharge voltage of the prepared fluorinated carbon is 3.51V (vs. Li / Li). + The median discharge voltage is 3.49V (vs. Li / Li). + The discharge specific capacity is 608mAh / g.
[0073] Example 5
[0074] 100g of amorphous carbon, identical to that in Example 4, was weighed and evenly spread in a nickel reactor to ensure the fluorination reaction proceeded. The furnace was evacuated to -0.1MPa using a vacuum pump. A fluorine-nitrogen atmosphere (with fluorine accounting for 10% of the volume) was introduced to 0.2MPa, and the fluorination reaction was carried out at 50°C. After fluorination for 24 hours, fluorinated carbon was obtained. The corresponding nitrogen isothermal adsorption curve is shown below. Figure 13 As shown, the specific surface area measured by the BET method is 985 m². 2 / g.
[0075] Fluorinated carbon electrodes and coin cells were prepared according to the method in Example 1, and constant current discharge tests were performed on them. The discharge curves are shown below. Figure 14 As shown, from Figure 14 It can be seen that the initial discharge voltage of the prepared fluorinated carbon is 3.50V (vs. Li / Li). + The median discharge voltage is 3.48V (vs. Li / Li). + The discharge specific capacity is 680mAh / g.
[0076] Example 6
[0077] 100g of amorphous carbon (PC-2) purchased from Foshan Perls Carbon Materials Technology Co., Ltd. was weighed and evenly spread inside the nickel reactor to ensure the fluorination reaction proceeded. The nitrogen isothermal adsorption curve of the selected amorphous carbon is shown below. Figure 15 As shown, the specific surface area measured by the BET method is 1061 m². 2 / g; The furnace was evacuated to -0.1MPa using a vacuum pump; A fluorine-nitrogen atmosphere (of which fluorine accounts for 30% of the volume) was introduced to 0.5MPa, and a fluorination reaction was carried out at 20℃. After fluorination for 36h, fluorinated carbon was obtained.
[0078] The nitrogen isotherm adsorption curve of the obtained carbon fluoride is as follows: Figure 16 As shown, the specific surface area measured by the BET method is 542 m². 2 / g. The X-ray photoelectron spectroscopy results of the obtained fluorinated carbon material are as follows: Figure 17 As shown, the atomic percentages of carbon, fluorine, and oxygen in the prepared fluorinated carbon are 57.20%, 36.57%, and 6.23%, respectively.
[0079] Fluorinated carbon electrodes and coin cells were prepared according to the method in Example 1, and constant current discharge tests were performed on them. The discharge curves are shown below. Figure 18 As shown, from Figure 18 It can be seen that the initial discharge voltage of the prepared fluorinated carbon is 3.33V (vs. Li / Li). + The median discharge voltage is 3.25V (vs. Li / Li). + The discharge specific capacity is 598mAh / g.
[0080] Comparative Example 1
[0081] Commercially available fluorinated graphite (purchased from Huawiray Chemical Co., Ltd., model HWG29916) was used as a comparison. Fluorinated carbon electrodes and coin cells were prepared according to the method in Example 1, and constant current discharge tests were performed on them. The discharge curves are shown below. Figure 19 As shown, from Figure 19 It can be seen that the initial discharge voltage of commercially available fluorinated graphite is 2.46V (vs. Li / Li).+ The median discharge voltage is 2.52V (vs. Li / Li). + The discharge specific capacity is 850mAh / g.
[0082] Comparative Example 2
[0083] Commercially available fluorinated porous carbon (fluorinated porous carbon purchased from Xiamen Zhongke Xifu Technology Co., Ltd., model number 103095) was used as a comparison. Fluorinated carbon electrodes and coin cells were prepared according to the method in Example 1, and constant current discharge tests were performed on them. The discharge curves are shown below. Figure 20 As shown, from Figure 20 It can be seen that the initial discharge voltage of commercially available fluorinated porous carbon is 2.96V (vs. Li / Li). + The median discharge voltage is 2.78V (vs. Li / Li). + The discharge specific capacity is 796mAh / g.
[0084] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.
Claims
1. A method for preparing high-discharge-voltage fluorinated carbon, characterized in that, Includes the following steps: Amorphous carbon is fluorinated in a fluorine-containing atmosphere to obtain the high discharge voltage fluorinated carbon. The amorphous carbon has a hierarchical porous structure; The specific surface area of the amorphous carbon is 2331~3500 m². 2 / g; The fluorination temperature is 20~50℃; The high-discharge-voltage fluorinated carbon has a discharge voltage of 3.50~3.52V (vs. Li / Li). + ).
2. The preparation method according to claim 1, characterized in that, The fluorination time is 12~36h.
3. The preparation method according to claim 1, characterized in that, The fluorination pressure is 0.01~0.5MPa.
4. The preparation method according to claim 1, characterized in that, The fluorine-containing atmosphere includes fluorine gas and a protective gas, wherein the protective gas includes at least one of nitrogen, argon and helium. The volume ratio of fluorine gas in the fluorine-containing atmosphere is 10-30%.
5. High discharge voltage fluorinated carbon prepared by the preparation method according to any one of claims 1 to 4.
6. The high discharge voltage fluorinated carbon according to claim 5, characterized in that, Based on atomic percentage, the high discharge voltage fluorinated carbon comprises 50-70% carbon, 20-40% fluorine, and 5-20% oxygen.
7. The high discharge voltage fluorinated carbon according to claim 5, characterized in that, The specific surface area of the high-discharge-voltage fluorinated carbon is not less than 300 m². 2 / g.
8. The use of high discharge voltage fluorinated carbon as a positive electrode according to any one of claims 5 to 7 in a primary battery.
Citation Information
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