Method for preparing carbon fluoride material by hydrothermal-carbonization

Abstract

The application discloses a method for preparing fluorocarbon material by using a hydrothermal-carbonization method and belongs to the technical field of synthetic materials. The method for preparing fluorocarbon material by using the hydrothermal-carbonization method comprises the following steps: carrying out a hydrothermal reaction on a mixture containing fluorobenzene dicarboxylic acid, a chromium salt, acetic acid and water, and then carrying out carbonization treatment after drying to obtain the fluorocarbon material. The organic framework compound formed by the hydrothermal reaction of the chromium salt and the fluorobenzene dicarboxylic acid is subjected to carbonization treatment, the obtained fluorocarbon material has uniformly distributed C(sp 2 )‑F bond discharge active centers, and the lithium battery discharge product C(sp 2 )‑FLi is uniformly distributed in the high-conductivity conjugated sp 2 carbon skeleton, when charging, Li 2 and electrons can be easily dissociated from the discharge product C(sp + )‑FLi, and this is favorable for realizing secondary use of the positive electrode material, and the method can be used for preparing a rechargeable secondary lithium-fluorocarbon battery.

Description

Technical Field

[0001] This invention belongs to the field of synthetic materials technology, and particularly relates to a method for preparing fluorinated carbon materials using a hydrothermal-carbonization method. Background Technology

[0002] Lithium-carbon fluoride batteries are solid-state lithium primary batteries with metallic lithium as the negative electrode and carbon fluoride as the positive electrode. The battery discharges based on the reaction between the carbon fluoride positive electrode and metallic lithium to form lithium fluoride. Due to the low mass density of the positive and negative electrode materials and the large potential difference, it possesses an extremely high energy density (700 Wh·kg⁻¹). -1 Furthermore, it has advantages such as good storage performance, resistance to extreme environmental temperatures (>400℃), long shelf life, very low self-discharge rate, and average annual capacity loss of less than 1%, and is widely used in various fields such as spacecraft, interplanetary exploration, military, consumer electronics, and medical.

[0003] Despite these advantages, lithium-carbon fluoride (CFx) batteries are currently only used as primary batteries and not as rechargeable batteries due to issues such as the high stability and low conductivity of the positive electrode discharge product LiF, and the growth of lithium dendrites at the negative electrode. However, with the increasing demand for advanced power sources in space exploration and special operations, the need for high-energy-density, environmentally tolerant rechargeable batteries is growing. CFx, as the cathode material, significantly impacts battery performance. CFx is a carbon derivative without a minimum repeating unit, composed of multiple fluorinated nanodomains. Its structure is primarily influenced by the structure of the carbon material and the fluorination process. The carbon material not only affects the CFx framework structure but also the ease of the fluorination process. The synthesis methods for CFx can be mainly divided into direct gas fluorination, indirect fluorination, and plasma-assisted fluorination. The CF bond and F / C ratio largely depend on the carbon raw materials and fluorination conditions, including the fluorinating agent, temperature, and reaction time. Currently, the key to CFx materials lies in the design of the carbon material and the optimization of fluorination conditions.

[0004] The reason why existing lithium-carbon fluoride batteries are difficult to recycle is primarily because the addition fluorination process of carbon raw materials in the current cathode material, carbon fluoride, destroys the original conjugated sp... 2 Carbon skeleton, and the obtained C(sp) 3 The -F bonds are extremely unevenly distributed, concentrated in the defect regions of the original carbon material. After battery discharge, they form blocky LiF with extremely poor conductivity. Furthermore, LiF is in an electrically insulating state, resulting in extremely high polarization voltage during charging. Additionally, due to the strong ionic bonds between Li and F atoms, Li atoms are firmly bound around F atoms, making it difficult for them to oxidize and dissociate to release Li. + The dissociation energy of electrons (e) is 6.1 eV. These issues severely restrict the development of rechargeable lithium-carbon fluoride batteries and are key problems that must be solved in their development.

[0005] Among the reported methods, a series of CF-based approaches were designed. x The composite cathode combines inorganic carbon materials with various forms of conductive additives, coatings, and composite components, which expands the interfacial contact area, promotes electron transport, accelerates the diffusion rate of lithium ions to the fluoride layer, and also promotes electron transport in the cathode. This improves the discharge performance of lithium-carbon fluoride batteries, especially at high rates, but it has not yet achieved a breakthrough in the rechargeability of lithium-carbon fluoride batteries. Summary of the Invention

[0006] To overcome the problems existing in the prior art, one of the objectives of this invention is to provide a method for preparing fluorinated carbon materials using a hydrothermal-carbonization method, wherein the fluorinated carbon material prepared by this method has a uniformly distributed C(sp) content. 2 The discharge products of )-FLi are beneficial for the secondary processing of fluorinated carbon materials.

[0007] The second objective of this invention is to provide a fluorinated carbon material prepared by the above method.

[0008] The third objective of this invention is to provide a fluorinated carbon cathode material comprising the above-mentioned fluorinated carbon material.

[0009] The fourth objective of this invention is to provide an application of the above-mentioned fluorinated carbon material or the above-mentioned fluorinated carbon cathode material in the preparation of secondary lithium-fluorinated carbon batteries.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] The first aspect of the present invention provides a method for preparing fluorocarbon materials using a hydrothermal-carbonization method, comprising the following steps: subjecting a mixture containing fluorophthalic acid, chromium salt, acetic acid and water to a hydrothermal reaction, drying and then performing a carbonization treatment to obtain the fluorocarbon material.

[0012] In some embodiments of the present invention, the fluorophthalic acid includes at least one of monofluorophthalic acid, difluorophthalic acid, trifluorophthalic acid, or tetrafluorophthalic acid; in some specific embodiments of the present invention, the fluorophthalic acid is selected from monofluorophthalic acid or tetrafluorophthalic acid; in some preferred embodiments of the present invention, the fluorophthalic acid is selected from tetrafluorophthalic acid.

[0013] This invention discovers that cathode materials obtained by using fluorinated carbon materials with different fluorine-to-carbon ratios have different electrochemical properties. Cathode materials with higher fluorine-to-carbon ratios result in batteries with higher specific capacity, a higher and more stable voltage plateau, and better cycle stability.

[0014] The fluorophthalic acid described in this invention refers to compounds obtained by replacing 1 to 4 hydrogen atoms on the benzene ring of phthalic acid with 1 to 4 fluorine atoms respectively. For example, monofluorophthalic acid is a compound obtained by replacing 1 hydrogen atom on the benzene ring of phthalic acid with 1 fluorine atom, difluorophthalic acid is a compound obtained by replacing 2 hydrogen atoms on the benzene ring of phthalic acid with 2 fluorine atoms respectively, and trifluorophthalic acid and tetrafluorophthalic acid are similar.

[0015] In some embodiments of the present invention, the monofluorophthalic acid includes at least one of 2-fluoroterephthalic acid, 2-fluoroisophthalic acid, or 3-fluorophthalic acid.

[0016] In some embodiments of the present invention, the tetrafluorophthalic acid includes at least one of 2,3,4,5,-tetrafluorophthalic acid, 2,4,5,6-tetrafluoroisophthalic acid, or 2,3,5,6-tetrafluoroterephthalic acid.

[0017] In some preferred embodiments of the present invention, the fluorophthalic acid is selected from 2-fluoroterephthalic acid or 2,3,4,5,-tetrafluorophthalic acid; more preferably, it is 2,3,4,5,-tetrafluorophthalic acid.

[0018] Preferably, the chromium salt is selected from trivalent chromium salts; more preferably, the chromium salt includes at least one of chromium nitrate, chromium sulfate, or chromium chloride; even more preferably, the chromium salt is selected from chromium nitrate, and more preferably, chromium nitrate nonahydrate.

[0019] Preferably, the mass ratio of fluorophthalic acid to chromium salt is (0.4-1.8):1; more preferably (0.5-1.4):1.

[0020] Preferably, the ratio of water to chromium salt is (15-25) mL: 1 g; more preferably (18-22) mL: 1 g.

[0021] Preferably, the ratio of acetic acid to chromium salt is (1-2) mL: 1 g; more preferably (1.2-1.5) mL: 1 g.

[0022] Preferably, the temperature of the hydrothermal reaction is 150–240°C; more preferably 180–230°C; and even more preferably 200–220°C.

[0023] Preferably, the hydrothermal reaction time is 10-16 hours; more preferably 8-12 hours.

[0024] Preferably, the drying temperature after the hydrothermal reaction is 70–80°C.

[0025] Preferably, the drying time after the hydrothermal reaction is 8 to 12 hours.

[0026] In some embodiments of the present invention, the drying method is drying; more specifically, oven drying.

[0027] Preferably, the carbonization temperature is 600–850°C; more preferably, it is 700–800°C.

[0028] Preferably, the carbonization treatment time is 3 to 10 hours; more preferably 6 to 9 hours.

[0029] Preferably, the carbonization process is carried out in a protective gas atmosphere; the protective gas preferably includes nitrogen, argon, or a combination thereof.

[0030] A second aspect of the present invention provides a fluorinated carbon material prepared by the method described in the first aspect of the present invention.

[0031] In some embodiments of the present invention, the fluorinated carbon material has a spherical structure.

[0032] In some embodiments of the present invention, the average particle size of the fluorinated carbon material is 10 to 100 nm.

[0033] A third aspect of the present invention provides a fluorinated carbon cathode material, comprising a conductive carrier and a conductive slurry, wherein the conductive slurry is stacked on the surface of the conductive carrier, and the raw materials for preparing the conductive slurry include the fluorinated carbon material described in the first aspect of the present invention.

[0034] Preferably, the raw materials for preparing the conductive slurry further include at least one of conductive carbon material, binder, or solvent; more preferably, the raw materials for preparing the conductive slurry further include conductive carbon material, binder, and solvent.

[0035] Preferably, the conductive carbon material includes at least one of conductive carbon black, conductive graphite, carbon nanotubes, carbon powder, or graphene.

[0036] Preferably, the mass ratio of the fluorinated carbon material to the conductive carbon material is (7-9):1.

[0037] Preferably, the adhesive comprises polyvinylidene fluoride (PVDF), peroxyacetyl nitrate (PAN), or a combination thereof.

[0038] Preferably, the mass ratio of the binder to the conductive carbon material is (0.4-2):1; more preferably (1-2):1.

[0039] Preferably, the solvent includes N-methylpyrrolidone, N,N-dimethylpyrrolidone, or a combination thereof.

[0040] Preferably, the conductive carrier includes at least one of foamed copper, copper foil, double-sided carbon-containing aluminum foil, carbon paper, or foamed nickel; more preferably, the conductive carrier is selected from double-sided carbon-containing aluminum foil or carbon paper.

[0041] In some embodiments of the present invention, the fluorinated carbon cathode material is prepared by a method comprising the following steps: mixing fluorinated carbon material, conductive carbon material, binder and solvent to prepare the conductive slurry, and applying the conductive slurry onto the conductive carrier to obtain the fluorinated carbon cathode material.

[0042] In some embodiments of the present invention, in the preparation method of the fluorinated carbon cathode material, the fluorinated carbon material, the conductive carbon material and the binder are first mixed and ground, and then a solvent is added for mixing; the grinding time is preferably 20 to 40 minutes.

[0043] In some embodiments of the present invention, in the method for preparing the fluorinated carbon cathode material, the conductive slurry is dried after being applied to the conductive carrier.

[0044] Preferably, the drying process after applying the conductive paste to the conductive carrier includes the following steps: drying in an oven at 35–60°C for 5–10 hours, followed by vacuum drying for 10–20 hours; more preferably, it includes the following steps: drying in an oven at 40–60°C for 5–6 hours, followed by vacuum drying for 10–14 hours.

[0045] The fourth aspect of the present invention provides the application of the fluorinated carbon material described in the second aspect of the present invention, or the fluorinated carbon cathode material described in the third aspect of the present invention, in the preparation of secondary lithium-fluorinated carbon batteries.

[0046] In some embodiments of the present invention, the secondary lithium-fluorinated carbon battery includes the fluorinated carbon positive electrode, separator, lithium negative electrode and electrolyte described in the third aspect of the present invention, wherein the separator is disposed between the fluorinated carbon positive electrode and the lithium negative electrode.

[0047] The beneficial effects of this invention are: by carbonizing the organic framework compound formed by the hydrothermal reaction of chromium salt and fluorophthalic acid, the fluorinated carbon material obtained has a uniformly distributed C(sp) content. 2 The )-F bond discharge active center is beneficial to the discharge product C(sp) of lithium batteries. 2 )-FLi in highly conductive conjugated sp 2 The uniform distribution of carbon atoms in the middle of the carbon skeleton allows the highly electronegative F atoms to not only gain electrons from Li atoms, but also to polarize C(sp). 2 The conjugated large π-bond electrons of ) weaken the strong ionic bond of LiF (dissociation energy 4.7 eV), allowing it to more easily dissociate from the discharge product C(sp) during charging. 2Li dissociates from )-FLi and releases Li + The presence of electrons facilitates the secondary processing of cathode materials, which can be used to prepare rechargeable secondary lithium-fluoride carbon batteries.

[0048] Specifically, compared with the prior art, the present invention has the following advantages:

[0049] 1. This invention is based on pre-fluorinated precursor technology, which first introduces fluorine atoms into the raw material, followed by hydrothermal reaction and carbonization treatment. This avoids the damage to the original conjugated sp atoms during subsequent addition fluorination. 2 Destruction of the carbon skeleton.

[0050] 2. The organic framework compound synthesized by the hydrothermal reaction of chromium salt and fluorophthalic acid in this invention is a MIL-101 type MOF with an MTN-e topology. Due to the kinetic stability of Cr compounds, the synthesized MIL-101(Cr) also has excellent thermal and chemical stability. The fluorinated carbon material obtained after subsequent carbonization treatment also has good thermal and chemical stability.

[0051] 3. This invention uses glacial acetic acid of appropriate concentration to replace conventional hydrofluoric acid in the synthesis of MIL-101(Cr), resulting in a product with a higher specific surface area. The average particle size of the synthesized MIL-101(Cr) crystals is reduced to below 100nm. Furthermore, using chromium nitrate and terephthalic acid as raw materials, water can be used as a solvent, making it safer and more environmentally friendly.

[0052] 4. By adjusting the number of fluorine substituents in fluorophthalic acid, the fluorine-carbon ratio of the material can be adjusted. In this invention, the cathode material with a higher fluorine-carbon ratio produces a battery with a higher specific capacity, a higher and more stable voltage platform, and better cycle stability. Attached Figure Description

[0053] Figure 1 The image shows the XRD pattern of the 2-fluoroterephthalic acid precursor powder and its carbonization in Example 1.

[0054] Figure 2 The image shows the SEM image of the 2-fluoroterephthalic acid precursor powder and its carbonization in Example 1.

[0055] Figure 3 This is a charge-discharge curve of the battery in Example 1 at a 0.1C rate.

[0056] Figure 4 This is a graph showing the cycle efficiency of the battery in Example 1.

[0057] Figure 5 The image shows the XRD pattern of the 2,3,4,5,-tetrafluorophthalic acid precursor powder and its carbonization in Example 2.

[0058] Figure 6 The image shows the SEM images of the 2,3,4,5,-tetrafluorophthalic acid precursor powder and its carbonized form from Example 2.

[0059] Figure 7 This is a charge-discharge curve of the battery in Example 2 at a 0.1C rate.

[0060] Figure 8 This is a graph showing the cycle efficiency of the battery in Example 2. Detailed Implementation

[0061] The following specific embodiments further illustrate the content of the present invention in detail. It should also be understood that the following embodiments are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the principles described herein are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not intended to be limited to the specific data in the examples below. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0062] Example 1

[0063] This example provides a fluorocarbon material and its application, specifically including the following steps:

[0064] (1) Preparation of fluorinated carbon materials:

[0065] Metal-organic frameworks (MOFs) were synthesized via a hydrothermal method using 2-fluoroterephthalic acid (2-fluoroterephthalic acid) as a ligand, followed by carbonization. 0.92 g of 2-fluoroterephthalic acid, 2 g of chromium(III) nitrate nonahydrate, 2.5 ml of glacial acetic acid, and 40 ml of ultrapure water were weighed and mixed thoroughly. The mixture was stirred with a magnetic stirrer for 30 min and then transferred to a high-pressure hydrothermal reactor. The reactor was placed in a 220°C oven and reacted for 8 h. After natural cooling, the mixture was washed twice by centrifugation with ultrapure water and ethanol, respectively. After drying for 12 h, 2-fluoroterephthalic acid (F-H2BDC) precursor powder was obtained. This precursor powder was ground and placed in a 25 ml crucible, then calcined in a tube furnace at a heating rate of 5°C / min under a nitrogen atmosphere at 800°C for 8 h to obtain the carbonized fluorinated carbon material.

[0066] (2) Preparation of fluorinated carbon cathode material:

[0067] Weigh 100 mg of the fluorinated carbon material, 12.5 mg of conductive carbon black (Super P), and 12.5 mg of polyvinylidene fluoride (PVDF) from step (1) above into an agate mortar. Grind for 20 minutes until completely fine. Then, add 400 μL of N,N-dimethylpyrrolidone using a pipette and continue grinding until the slurry is completely and evenly mixed. Next, coat the conductive slurry onto a conductive carrier. Dry the loaded material in a 40°C oven for 3 hours, then transfer it to a vacuum drying oven for 12 hours to obtain the fluorinated carbon cathode material. Cut the cathode material into circular pieces with a diameter of 10 mm and a loading of 1-3 mg / cm³. -2 spare.

[0068] (3) Full cell preparation:

[0069] Take the positive electrode material disc from step (2) as the positive electrode, the lithium metal sheet with a diameter of 15.6 mm as the negative electrode, the electrolyte as 1M LiBF4 (solvent is DME:PC = 1:1 Vol%), the separator as 19 mm PP separator, add gaskets and spring sheets and assemble them in a glove box to form a 2032 button battery.

[0070] Example 2

[0071] This example provides a fluorocarbon material and its application, specifically including the following steps:

[0072] (1) Preparation of fluorinated carbon materials:

[0073] Metal-organic frameworks (MOFs) were synthesized via a hydrothermal method using 2,3,4,5,-tetrafluorophthalic acid (2,3,4,5,-tetrafluorophthalic acid) as a ligand, followed by carbonization. 1.19 g of 2,3,4,5,-tetrafluorophthalic acid, 2 g of chromium(III) nitrate nonahydrate, 2.5 ml of glacial acetic acid, and 40 ml of ultrapure water were weighed and mixed thoroughly. The mixture was stirred magnetically for 30 min and then transferred to a high-pressure hydrothermal reactor. The reactor was placed in a 220°C oven and reacted for 8 h. After natural cooling, the mixture was washed twice by centrifugation with ultrapure water and ethanol, respectively. After drying for 12 h, 2,3,4,5,-tetrafluorophthalic acid (4F-H2PDA) precursor powder was obtained. This precursor powder was ground and placed in a 25 mL crucible, then calcined in a tube furnace at a heating rate of 5°C / min under a nitrogen atmosphere at 800°C for 8 h to obtain the carbonized fluorinated carbon material.

[0074] (2) Preparation of fluorinated carbon cathode material:

[0075] Weigh 100 mg of the fluorinated carbon material, 12.5 mg of conductive carbon black (Super P), and 12.5 mg of polyvinylidene fluoride (PVDF) from step (1) above into an agate mortar. Grind for 20 minutes until completely fine. Then, add 400 μL of N,N-dimethylpyrrolidone using a pipette and continue grinding until the slurry is completely mixed. Next, coat the conductive slurry onto a conductive carrier. Dry the loaded material in a 40°C oven for 3 hours, then transfer it to a vacuum drying oven for 12 hours to obtain the fluorinated carbon cathode material. Cut the cathode material into 10 mm diameter discs with a loading of 1-3 mg / cm³. -2 spare.

[0076] (3) Full cell preparation:

[0077] Take the positive electrode material disc from step (2) as the positive electrode, the lithium metal sheet with a diameter of 15.6 mm as the negative electrode, the electrolyte as 1M LiBF4 (solvent is DME:PC = 1:1 Vol%), the separator as 19 mm PP separator, add gaskets and spring sheets and assemble them in a glove box to form a 2032 button battery.

[0078] Performance Tests and Results

[0079] 1. XRD and SEM images of the precursor powder and its carbonized form in the test examples.

[0080] 2. Electrochemical performance of the full cells prepared in the test examples.

[0081] Figure 1 The image shows the XRD pattern of the 2-fluoroterephthalic acid (F-H2BDC) precursor powder and its carbonized form from Example 1. Figure 1 It can be seen that the F-H2BDC precursor powder has sharp peaks before carbonization, indicating good crystallinity, while the peak trend decreases after carbonization, indicating reduced crystallinity. Figure 2 The images show SEM images of the 2-fluoroterephthalic acid (F-H2BDC) precursor powder and its carbonized form from Example 1. (a) is before carbonization, and (b) is after carbonization. Figure 2 It can be seen that the F-H2BDC precursor powder is spherical, and after carbonization, the spherical shape is obvious, with an average particle size of about 100nm. Figure 3 This is a charge-discharge curve of the battery in Example 1 at a 0.1C rate. Figure 4 The circuit efficiency diagram of the battery in Example 1 is shown below. Figures 3-4 It can be seen that the battery in Example 1 can continue to charge and discharge for 50 more cycles after the first charge and discharge cycle, which proves the feasibility of the secondary battery. The fluorinated carbon material prepared in Example 1 can be used to prepare secondary lithium-fluorinated carbon batteries.

[0082] Figure 5The image shows the XRD pattern of the 2,3,4,5,-tetrafluorophthalic acid (4F-H2PDA) precursor powder and its carbonized form from Example 2. Figure 5 It can be seen that, compared with the carbonized form, the peaks of the 4F-H2PDA precursor powder before carbonization are sharper, indicating that the degree of carbonization is better. Figure 6 The images show SEM images of the 2,3,4,5,-tetrafluorophthalic acid (4F-H2PDA) precursor powder and its carbonized form from Example 2. (a) is before carbonization, and (b) is after carbonization. Figure 6 It can be seen that the F-H2BDC precursor powder has a vague spherical shape before carbonization, and the spherical shape is more obvious after carbonization, with an average particle size of about 100nm. Figure 7 This is a charge-discharge curve of the battery in Example 2 at a rate of 0.1C. Figure 8 The circuit efficiency diagram of the battery in Example 2 is shown below. Figures 7-8 It can be seen that the battery of Example 2 can continue to be charged and discharged for 50 more cycles after the first charge and discharge cycle, proving the feasibility of the rechargeable battery. The fluorinated carbon material prepared in Example 2 can be used to prepare rechargeable lithium-fluorinated carbon batteries. Furthermore, compared with the battery of Example 1, the battery of Example 2 has a higher capacity, a more stable and higher voltage platform, and better cycle stability.

[0083] In this invention, the organic framework compound synthesized via a hydrothermal reaction of chromium salts and fluorophthalic acid is a MIL-101 type MOF with an MTN-e topology. Due to the kinetic stability of chromium compounds, the synthesized MIL-101(Cr) also exhibits excellent thermal and chemical stability. The fluorocarbon material obtained after subsequent carbonization also possesses good thermal and chemical stability. Furthermore, the use of a suitable concentration of glacial acetic acid in this embodiment can replace the role of conventional hydrofluoric acid in the synthesis of MIL-101(Cr), resulting in a product with a higher specific surface area. The average particle size of the synthesized MIL-101(Cr) crystals is reduced to below 100 nm. Moreover, the use of chromium nitrate and terephthalic acid as raw materials allows for the use of water as a solvent, making it safer and more environmentally friendly.

[0084] As can be seen from the comparison of Examples 1 and 2, the fluorine-carbon ratio of the material can be adjusted by adjusting the number of fluorine substituents in fluorophthalic acid. Furthermore, the battery obtained by the cathode material with a higher fluorine-carbon ratio has a higher specific capacity, a higher and more stable voltage platform, and better cycle stability.

[0085] This invention is based on pre-fluorinated precursor technology, which first introduces fluorine atoms into the raw material, followed by hydrothermal reaction and carbonization treatment. This avoids the damage to the original conjugated sp atoms during subsequent addition fluorination. 2 The destruction of the carbon skeleton yields fluorinated carbon materials that can be used to prepare secondary lithium-fluorinated carbon batteries.

[0086] In summary, this invention utilizes the carbonization treatment of an organic framework compound formed by the hydrothermal reaction of chromium salts and fluorophthalic acid to obtain a fluorinated carbon material with a uniformly distributed C(sp) content. 2 The )-F bond discharge active center is beneficial to the discharge product C(sp) of lithium batteries. 2 )-FLi in highly conductive conjugated sp 2 The uniform distribution of carbon atoms in the middle of the carbon skeleton allows the highly electronegative F atoms to not only gain electrons from Li atoms, but also to polarize C(sp). 2 The conjugated large π-bond electrons of ) weaken the strong ionic bond of LiF (dissociation energy 4.7 eV), allowing it to more easily dissociate from the discharge product C(sp) during charging. 2 Li dissociates from )-FLi and releases Li + The presence of electrons facilitates the secondary processing of cathode materials, which can be used to prepare rechargeable secondary lithium-fluoride carbon batteries.

Claims

1. The application of a fluorinated carbon cathode material in the preparation of secondary lithium-fluorinated carbon batteries, characterized in that, The fluorinated carbon cathode material includes a conductive carrier and a conductive slurry, wherein the conductive slurry is stacked on the surface of the conductive carrier, and the raw materials for preparing the conductive slurry include fluorinated carbon materials; The fluorocarbon material is prepared using a hydrothermal-carbonization method, comprising the following steps: subjecting a mixture containing fluorophthalic acid, chromium salt, acetic acid, and water to a hydrothermal reaction, followed by drying and carbonization treatment to obtain the fluorocarbon material; the hydrothermal reaction temperature is 200~220℃; the hydrothermal reaction time is 8~12h; the carbonization treatment temperature is 700~800℃; and the carbonization treatment time is 6~9h. The fluorophthalic acid is selected from tetrafluorophthalic acid; the tetrafluorophthalic acid includes 2, 3, 4, 5, Tetrafluorophthalic acid, 2,4,5,6 Tetrafluoroisophthalic acid or 2,3,5,6 At least one of tetrafluoroterephthalic acid; the chromium salt is selected from trivalent chromium salts; The fluorocarbon material has a spherical structure; the average particle size of the fluorocarbon material is 10~100nm.

2. The application according to claim 1, characterized in that, The mass ratio of fluorophthalic acid to chromium salt is (0.4~1.8):1; And / or, the ratio of water to chromium salt is (15~25) mL: 1 g; And / or, the ratio of acetic acid to chromium salt is (1~2) mL: 1 g.

3. The application according to claim 1, characterized in that, The raw materials for preparing the conductive slurry also include at least one of conductive carbon material, binder, or solvent.

4. The application according to claim 3, characterized in that, The conductive carbon material includes at least one of conductive carbon black, conductive graphite, carbon nanotubes, carbon powder, and graphene. And / or, the adhesive comprises polyvinylidene fluoride, peroxyacetyl nitrate, or a combination thereof; And / or, the solvent includes N-methylpyrrolidone, N,N-dimethylpyrrolidone, or a combination thereof.

Images