Preparation method of negative electrode material with fluorinated interfacial film and battery

Abstract

The invention discloses a preparation method of a negative electrode material with a fluorinated interfacial film and a battery, and relates to the technical field of batteries. Comprising the following steps: laying a net layer on the negative plate, and pressing the net layer to form a plurality of grooves in the surface of the negative plate; and dissolving fluoride in a solvent to prepare a fluorination treatment solution, immersing the negative electrode plate with the groove in the surface in the fluorination treatment solution, stirring, cleaning, and drying to obtain the composite negative electrode plate with a fluorination interface layer attached on the surface. The patterned structure can be formed on the surface of the lithium metal negative electrode so as to change the deposition mode of lithium ions, the problem of non-uniform deposition of lithium is solved, and under the dual action of the fluorinated layer and the patterned surface of the lithium negative electrode, the lithium ions are uniformly deposited under the fluorinated layer instead of being gathered at the edge of the pattern after continuous deposition, so that the lithium metal negative electrode is more uniform in deposition. Therefore, the problem of lithium dendrite growth is solved.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and specifically relates to a method for preparing a negative electrode material with a fluorinated interface film and a battery. Background Art

[0002] Lithium-ion batteries have a much higher energy density than traditional batteries, and can provide longer battery life and stronger performance support under the same weight. In addition, lithium-ion batteries also have the advantages of long life, low self-discharge rate, fast charging ability, and environmental friendliness, and are mainly used in new energy vehicles, renewable energy storage systems, and smart device fields.

[0003] The lithium metal in lithium-ion batteries has high reactivity, making it difficult to maintain a stable and uniform interface on the surface of the lithium metal negative electrode, which will cause local aggregation of electrons and ions, generating uncontrollable lithium dendrites and "dead lithium", seriously threatening the safety and stability of the battery; in some related patents, a lithium fluoride film is prepared by placing a polished lithium sheet in a fluorinating agent solution under high-temperature reaction, but the heating temperature of the above method is too high, and safety accidents are likely to occur during the heating process, which is not suitable for industrial production. Secondly, only patterning the lithium alone, under the action of an electric field, subsequent lithium ions tend to aggregate at the edges of the grooves of the pattern, gradually turning into lithium dendrites, reducing the cycle life of the battery, and increasing the risk of battery circuit and thermal runaway. Summary of the Invention

[0004] In order to solve at least one of the problems mentioned in the above background art, this application provides a method for preparing a negative electrode material with a fluorinated interface film and a battery, which can form a patterned structure on the surface of the lithium metal negative electrode to change the deposition mode of lithium ions, improve the problem of uneven lithium deposition, and under the dual action of the fluorinated layer and the patterned surface of the lithium negative electrode, after continuous deposition, it is realized that lithium ions do not aggregate at the pattern edges, but are uniformly deposited under the fluorinated layer, thereby solving the problem of lithium dendrite growth.

[0005] The specific technical solutions provided by the embodiments of this application are as follows:

[0006] In a first aspect, a method for preparing a negative electrode material with a fluorinated interface film is provided. The negative electrode material includes a negative electrode sheet, and the method includes:

[0007] Laying a mesh layer on the negative electrode sheet and pressing the mesh layer to form a plurality of grooves on the surface of the negative electrode sheet;

[0008] Dissolving a fluoride in a solvent to prepare a fluorination treatment solution, immersing the negative electrode sheet with grooves on its surface in the fluorination treatment solution, and performing stirring, cleaning, and drying treatments to obtain a composite negative electrode sheet with a fluorinated interface layer attached to its surface.

[0009] In a specific embodiment, the grooves are spaced and evenly distributed on the surface of the negative electrode sheet, and the depth of the grooves is 2 to 10 μm.

[0010] Furthermore, the depth of the grooves in this embodiment is set to include one of 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, or 10 μm.

[0011] In a specific embodiment, the mesh layer is a stainless steel mesh with a number of mesh holes spaced apart. The mesh layer is pressed using a template pressing method and a preset pressure is set to press the mesh layer to form the grooves on the negative electrode sheet.

[0012] In a specific embodiment, the thickness of the negative electrode sheet is 10 to 20 μm.

[0013] Furthermore, the thickness of the lithium foil of the negative electrode sheet is set to include one of 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, 19 μm, 19.5 μm, or 20 μm.

[0014] In a specific embodiment, the concentration of the fluorination treatment liquid is 0.5 to 2 wt%.

[0015] Furthermore, the concentration of the fluorination treatment liquid in this embodiment is set to include one of 0.5 wt%, 0.6 wt%, 0.65 wt%, 0.7 wt%, 0.75 wt%, 0.8 wt%, 0.85 wt%, 0.9 wt%, 0.95 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, or 2 wt%.

[0016] In a specific embodiment, the fluoride is a metal fluoride, and the metal fluoride includes one or more of tin fluoride, copper fluoride, lead fluoride, chromium fluoride, magnesium fluoride, zinc fluoride, silver fluoride, ammonium fluoride.

[0017] In a specific embodiment, the solvent for dissolving the fluoride is an organic solvent, and the organic solvent includes one or more of dimethyl sulfoxide, acetonitrile, dimethylformamide, methanol, acetone, ethyl acetate, ether, chloroform, toluene, carbon tetrachloride.

[0018] In a specific embodiment, the thickness of the fluorinated interface layer on the composite negative electrode sheet is 10 to 500 nm.

[0019] Furthermore, the thickness of the fluorinated interface layer formed on the composite negative electrode sheet includes one or more of 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, or 500 nm.

[0020] In a specific embodiment, at room temperature, the negative electrode sheet with grooves on its surface is immersed in the fluorination treatment solution for 1 to 20 minutes.

[0021] After the immersion is completed, the treated negative electrode sheet is taken out, and the treated negative electrode sheet is washed with an organic solvent.

[0022] Furthermore, the immersion time of the negative electrode sheet with grooves on its surface in the fluorination treatment solution is 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes, or 20 minutes.

[0023] In a specific embodiment, vacuum drying is adopted, the drying temperature is 40 to 60 °C, and the drying time is 24 to 48 hours.

[0024] In a second aspect, a battery is provided, and the battery includes a negative electrode material, and the negative electrode material is prepared by using the preparation method of the negative electrode material with a fluorinated interface film as described above.

[0025] The embodiments of the present application have the following beneficial effects:

[0026] 1. The preparation method of the negative electrode material provided by the embodiments of the present application is as follows: First, lay a stainless steel mesh on the negative electrode sheet, and then adjust the pressure of pressing, and use the template pressing method to press the stainless steel mesh to form a number of grooves on the surface of the negative electrode sheet, where a number of grooves are arranged at equal intervals on the surface of the negative electrode sheet. Then, prepare a fluorination treatment solution, and immerse the negative electrode sheet with the pressed grooves in the above fluorination treatment solution. After a period of attachment, a fluorinated film layer is formed on the surface of the negative electrode sheet, and the fluorinated film layer covers the inside of the grooves and the side walls of the grooves, that is, it covers the entire surface layer of the negative electrode sheet. Through the above solution, the focusing current can force lithium to deposit in a specific area. At the same time, the existence of the fluorinated interface film further improves the interface stability between the lithium metal and the electrolyte, inhibits the growth of lithium dendrites under a large capacity, and the fluorinated film can promote the transmission of lithium ions and improve the battery reaction kinetics. Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0028] Figure 1 Schematic diagram showing the preparation method of the negative electrode material with a fluorinated interface film according to the present application;

[0029] Figure 2 Schematic diagram showing the formation of a number of grooves on the surface of the negative electrode sheet according to the present application;

[0030] Figure 3 Schematic diagram showing the composite negative electrode sheet with a fluorinated interface layer attached to the surface according to the present application;

[0031] Figure 4 Schematic diagram showing the voltage test results of the battery prepared according to the present application;

[0032] Figure 5 Schematic diagram showing the Coulomb efficiency test results of the battery prepared according to the present application. Detailed Embodiments

[0033] To make the purpose, technical solutions and advantages of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0035] In one embodiment, a method for preparing a negative electrode material with a fluorinated interface film is provided, wherein the negative electrode material includes a negative electrode sheet, and the negative electrode sheet in this embodiment is configured as a lithium negative electrode sheet, that is, a lithium foil, as Figure 1 shown, the method includes the following steps:

[0036] Step 101, lay a mesh layer on the negative electrode sheet and press the mesh layer to form a number of grooves on the surface of the negative electrode sheet.

[0037] It should be noted that, as Figure 2 shown, the mesh layer in this embodiment is a stainless steel mesh with a number of mesh holes distributed at intervals. During the pressing process, the template pressing method is adopted. First, lay the stainless steel mesh on the lithium foil and configure the length and width of the stainless steel mesh to be the same as that of the lithium foil to ensure that the stainless steel mesh can cover the lithium foil; after fixing the stainless steel mesh on the lithium foil, set a preset pressure to press the stainless steel mesh, and then start pressing to form a number of grooves on the surface of the lithium foil.

[0038] Furthermore, as Figure 2 shown, the grooves are evenly distributed at intervals on the surface of the negative electrode sheet, and the depth of the grooves is set to 2 - 10 μm. In order to ensure that the cooperation between the negative electrode sheet and the grooves can reach a better state, the thickness of the lithium foil of the negative electrode sheet is selected to be 10 - 20 μm.

[0039] It should be noted that the depth of the grooves in this embodiment is set to include but not limited to one of 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, or 10 μm.

[0040] At the same time, the thickness of the lithium foil of the negative electrode sheet is set to include but not limited to one of 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, 19 μm, 19.5 μm or 20 μm.

[0041] Specifically, the cross-sectional shape of the groove includes, but is not limited to, circular, rectangular, square or conical.

[0042] Step 102: Dissolve the fluoride in a solvent to prepare a fluorination treatment solution, immerse the negative electrode sheet with grooves on its surface in the fluorination treatment solution, and perform stirring, cleaning and drying treatments to obtain a composite negative electrode sheet with a fluorinated interface layer attached to its surface.

[0043] As Figure 3 shown, after completing the patterning treatment of pressing grooves on the negative electrode sheet, start the film coating treatment on the surface of the negative electrode sheet. First, dissolve the fluoride in a solvent to prepare a fluorination treatment solution. The fluoride is a metal fluoride, and the metal fluoride includes, but is not limited to, one or more of tin fluoride, copper fluoride, lead fluoride, chromium fluoride, magnesium fluoride, zinc fluoride, silver fluoride, ammonium fluoride. The solvent is an organic solvent, and the organic solvent includes, but is not limited to, one or more of dimethyl sulfoxide, acetonitrile, dimethylformamide, methanol, acetone, ethyl acetate, ether, chloroform, toluene, carbon tetrachloride.

[0044] To ensure that the thickness of the fluorinated interface layer formed on the surface of the film-coated negative electrode sheet is within a reasonable range, set the concentration of the fluorination treatment solution to 0.5 - 2 wt%, and dissolve the fluoride in the solvent and stir for 30 - 60 min.

[0045] It should be noted that the concentration of the fluorination treatment solution set in this embodiment includes, but is not limited to, one of 0.5 wt%, 0.6 wt%, 0.65 wt%, 0.7 wt%, 0.75 wt%, 0.8 wt%, 0.85 wt%, 0.9 wt%, 0.95 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt% or 2 wt%.

[0046] Further, after immersing the negative electrode sheet with grooves on its surface in the fluorination treatment solution, at room temperature, set the negative electrode sheet with grooves on its surface to be immersed in the fluorination treatment solution for 1 - 20 min; after the immersion is completed, take out the treated negative electrode sheet, and clean the treated negative electrode sheet with an organic solvent. In this embodiment, the thickness of the fluorinated interface layer on the composite negative electrode sheet is 10 - 500 nm.

[0047] In this embodiment, the immersion time of the negative electrode sheet with grooves on its surface in the fluorination treatment liquid includes, but is not limited to, one of 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, or 20 min.

[0048] It should be noted that the thickness of the fluorinated interface layer formed on the composite negative electrode sheet in this embodiment includes, but is not limited to, one of 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, or 500 nm.

[0049] Among them, the organic solvents used for cleaning the negative electrode sheet after treatment include, but are not limited to, one or more of dimethyl sulfoxide, acetonitrile, dimethylformamide, methanol, acetone, ethyl acetate, ether, chloroform, toluene, and carbon tetrachloride.

[0050] It should be noted that in this embodiment, the vacuum drying method is used to dry the taken-out treated negative electrode sheet. After the drying temperature is 40 - 60 °C and the drying time is 24 - 48 h, a composite negative electrode sheet with a fluorinated interface layer attached to its surface is obtained. After the negative electrode sheet is immersed in the fluorination treatment liquid, the fluorination treatment liquid flows into the grooves, and a fluorinated interface layer is formed and attached to the bottom and side walls of the grooves, thereby realizing that the entire surface layer of the negative electrode sheet is covered with a fluorinated interface film. Through the above solution, the focusing current can force lithium to deposit in a specific area. At the same time, the presence of the fluorinated interface film further improves the interfacial stability between the lithium metal and the electrolyte, inhibits the growth of lithium dendrites under a large capacity, and the fluorinated film can promote the transmission of lithium ions and improve the battery reaction kinetics.

[0051] In one embodiment, corresponding to the above embodiment, a battery is provided. The battery includes a positive electrode material, an electrolyte, and a negative electrode material, wherein the negative electrode material is prepared by the preparation method of the negative electrode material with a fluorinated interface film as described above.

[0052] Example 1

[0053] Corresponding to the above embodiment, the present application provides a preparation method of a negative electrode material with a fluorinated interface film, which specifically includes:

[0054] Step (1): Pattern the lithium metal anode using the template pressing method. Lay a stainless steel mesh on the surface of the lithium foil. The length and width of the stainless steel mesh are the same as those of the lithium foil. After fixing, adjust the applied pressure so that grooves are evenly distributed on the surface of the lithium foil to achieve patterned pretreatment of the lithium anode:

[0055] Step (2): Dissolve 0.25 g of tin fluoride in 50 g of dimethyl sulfoxide. At room temperature, stir with a magnetic stirrer for 30 minutes to obtain a tin fluoride solution. Immerse the patterned lithium anode obtained in step (1) in the tin fluoride solution for 1 minute. Finally, wash the immersed anode sheet with dimethyl sulfoxide solvent and perform vacuum drying treatment. The drying temperature is 40 °C and the drying time is 24 hours to obtain a composite anode sheet with a fluorinated interfacial film. Among them, the thickness of the fluorinated interfacial layer on the composite anode sheet is 50 nm.

[0056] Example 2

[0057] Corresponding to the above embodiments, the present application provides a preparation method of a negative electrode material with a fluorinated interfacial film. The difference between this example and Example 1 is the immersion time of the anode sheet in the fluorination treatment solution, which specifically includes:

[0058] Step (1): Pattern the lithium metal anode using the template pressing method. Lay a stainless steel mesh on the surface of the lithium foil. The length and width of the stainless steel mesh are the same as those of the lithium foil. After fixing, adjust the applied pressure so that grooves are evenly distributed on the surface of the lithium foil to achieve patterned pretreatment of the lithium anode:

[0059] Step (2): Dissolve 0.25 g of tin fluoride in 50 g of dimethyl sulfoxide. At room temperature, stir with a magnetic stirrer for 30 minutes to obtain a tin fluoride solution. Immerse the patterned lithium anode obtained in step (1) in the tin fluoride solution for 10 minutes. Finally, wash the immersed anode sheet with dimethyl sulfoxide solvent and perform vacuum drying treatment. The drying temperature is 40 °C and the drying time is 24 hours to obtain a composite anode sheet with a fluorinated interfacial film. Among them, the thickness of the fluorinated interfacial layer on the composite anode sheet is 200 nm.

[0060] Example 3

[0061] Corresponding to the above embodiments, the present application provides a preparation method of a negative electrode material with a fluorinated interfacial film. The difference between this example and Example 1 is the immersion time of the anode sheet in the fluorination treatment solution, which specifically includes:

[0062] Step (1): Pattern the lithium metal anode using the template pressing method. Lay a stainless steel mesh on the surface of the lithium foil. The length and width of the stainless steel mesh are the same as those of the lithium foil. After fixing, adjust the applied pressure so that grooves are evenly distributed on the surface of the lithium foil to achieve patterned pretreatment of the lithium anode:

[0063] Step (2): Dissolve 0.25 g of tin fluoride in 50 g of dimethyl sulfoxide. At room temperature, stir with a magnetic stirrer for 30 minutes to obtain a tin fluoride solution; immerse the patterned lithium negative electrode obtained in step (1) in the tin fluoride solution for 20 minutes; finally, wash the immersed negative electrode sheet with dimethyl sulfoxide solvent and perform vacuum drying treatment at a drying temperature of 40 °C for 24 hours to obtain a composite negative electrode sheet with a fluorinated interfacial film. Among them, the thickness of the fluorinated interfacial layer on the composite negative electrode sheet is 500 nm.

[0064] Comparative Example 1

[0065] The difference between this example and Example 1 is that only grooves are pressed on the surface of the negative electrode sheet, and there is no fluorinated interfacial layer attached to the surface of the negative electrode sheet. Specifically, only the template pressing method is used to pattern the metallic lithium negative electrode. Lay a stainless steel mesh on the surface of the lithium foil. The length and width of the stainless steel mesh are the same as those of the lithium foil. After fixing, adjust the applied pressure so that there are evenly distributed grooves on the surface of the lithium foil.

[0066] Comparative Example 2

[0067] The difference between this example and Example 1 is that only a fluorinated interfacial layer is formed on the surface of the negative electrode sheet. Dissolve 0.25 g of tin fluoride in 50 g of dimethyl sulfoxide. At room temperature, stir with a magnetic stirrer for 30 minutes to obtain a tin fluoride solution; immerse the patterned lithium negative electrode obtained in step (1) in the tin fluoride solution for 1 minute; finally, wash the immersed negative electrode sheet with dimethyl sulfoxide solvent and perform vacuum drying treatment at a drying temperature of 40 °C for 24 hours to obtain a composite negative electrode sheet with a fluorinated interfacial film. Among them, the thickness of the fluorinated interfacial layer on the composite negative electrode sheet is 50 nm.

[0068] Obtain the lithium negative electrode sheets in each of the above-prepared examples and comparative examples. Disperse the positive electrode material NCM811, binder PVDF, and conductive agent carbon black in N-methylpyrrolidone and mix evenly to obtain a slurry, which is double-sided coated on an aluminum foil current collector, and after vacuum drying, it is die-cut to obtain a positive electrode sheet of a certain size. Assemble the positive electrode sheet, separator, and negative electrode sheet into a battery. Electrochemically test the assembled battery at 25 °C. Among them, a coin-type symmetric battery is used for constant current charge and discharge testing, and the test current is 1 mA*cm -1 . The assembled lithium metal battery is used for Coulomb efficiency testing, and the test voltage range is 2.8 - 4.3 V, and the test current is 1 A.

[0069] As Figure 4 and Figure 5As shown, by combining the test data in Embodiment 1 to Embodiment 3, it can be seen that by controlling other preparation conditions to be the same and setting different soaking times of the negative electrode sheet in the fluorination treatment solution, when within the feasible range of this embodiment, the longer the soaking time of the negative electrode sheet in the fluorination treatment solution, the thicker the thickness of the fluorinated interface layer finally formed on the composite negative electrode sheet. At the same time, by combining the test results of the Coulomb efficiency of the lithium battery prepared with the negative electrode material prepared above in the figure, it can be seen that the Coulomb efficiency of the prepared battery is above 80%, and the Coulomb efficiency of the battery prepared with the negative electrode material in Embodiment 2 is close to 90%; at the same time, from the voltage test results, it can be seen that the voltage duration of the lithium battery prepared with the negative electrode material prepared in this embodiment is above 300 hours, that is, it shows that through the preparation method in this embodiment, the focused current can force lithium to deposit in a specific area, and at the same time, the existence of the fluorinated interface film further improves the interfacial stability between the lithium metal and the electrolyte, inhibits the growth of lithium dendrites at high capacity, and the fluorinated film can promote the transport of lithium ions and improve the battery reaction kinetics.

[0070] As Figure 4 and Figure 5 shown, by combining the voltage tests and Coulomb test results in the above-mentioned Embodiment 1, Comparative Example 1 and Comparative Example 2, it can be seen that the voltage duration of the battery made of the negative electrode material prepared in Embodiment 1 of this application is above 350 hours, while the voltage durations of the batteries prepared in Comparative Example 1 and Comparative Example 2 are both below 300 hours; it can also be clearly seen from the Coulomb efficiency that the Coulomb efficiency of the battery made of the negative electrode material in Embodiment 1 of this application is significantly higher than that of the batteries in Comparative Example 1 and Comparative Example 2, indicating that through the preparation method in this embodiment, the focused current can force lithium to deposit in a specific area, and at the same time, the existence of the fluorinated interface film further improves the interfacial stability between the lithium metal and the electrolyte, inhibits the growth of lithium dendrites at high capacity, and the fluorinated film can promote the transport of lithium ions and improve the battery reaction kinetics.

[0071] Although the preferred embodiments in the embodiments of the present application have been described, those skilled in the art can make additional changes and modifications once they know the basic creative concepts. Therefore, the appended claims are intended to be interpreted to include the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0072] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A method for preparing a negative electrode material having a fluorinated interface film, characterized in that: The negative electrode material includes a negative electrode sheet, and the method includes: Laying a mesh layer on the negative electrode sheet, and pressing the mesh layer to form a plurality of grooves on the surface of the negative electrode sheet; The fluoride is dissolved in a solvent to prepare a fluoridation treatment solution, the negative electrode sheet with the groove on the surface is immersed in the fluoridation treatment solution, and after stirring, washing and drying, a composite negative electrode sheet with a fluoridation interface layer attached to the surface is obtained.

2. The method for preparing a negative electrode material having a fluorinated interface film according to claim 1, characterized in that: The grooves are spaced apart and evenly distributed on the surface of the negative electrode sheet, and the depth of the grooves is 2 to 10 μm.

3. The method for preparing a negative electrode material having a fluorinated interface film according to claim 1 or 2, characterized in that: The mesh layer is a stainless steel mesh with a plurality of mesh holes spaced apart from each other, and the method further comprises: A template pressing method is adopted, and a preset pressure is set to press the mesh layer to form the groove on the negative electrode sheet.

4. The method for preparing a negative electrode material having a fluorinated interface film according to claim 1 or 2, characterized in that: The thickness of the negative electrode sheet is 10 to 20 μm.

5. The method for preparing a negative electrode material having a fluorinated interface film according to claim 1 or 2, characterized in that: The concentration of the fluorination treatment solution is 0.5-2 wt %.

6. The method for preparing a negative electrode material having a fluorinated interface film according to claim 1 or 2, characterized in that: The fluoride is a metal fluoride, and the metal fluoride includes one or more of tin fluoride, copper fluoride, lead fluoride, chromium fluoride, magnesium fluoride, zinc fluoride, silver fluoride, and ammonium fluoride; And / or, the solvent used to dissolve the fluoride is an organic solvent, and the organic solvent includes one or more of dimethyl sulfoxide, acetonitrile, dimethylformamide, methanol, acetone, ethyl acetate, ether, chloroform, toluene, and carbon tetrachloride.

7. The method for preparing a negative electrode material having a fluorinated interface film according to claim 1 or 2, characterized in that: The thickness of the fluorinated interface layer on the composite negative electrode sheet is 10 to 500 nm.

8. The method for preparing a negative electrode material having a fluorinated interface film according to claim 1 or 2, characterized in that: The method further comprises: Under room temperature conditions, immersing the negative electrode sheet having the grooves on the surface in the fluorination treatment solution for 1 to 20 minutes; After the soaking is completed, the treated negative electrode sheet is taken out and cleaned with an organic solvent.

9. The method for preparing a negative electrode material having a fluorinated interface film according to claim 1 or 2, characterized in that: Vacuum drying is adopted, the drying temperature is 40-60°C, and the drying time is 24-48h.

10. A battery, characterized in that: The battery comprises a negative electrode material, and the negative electrode material is prepared by the method for preparing a negative electrode material having a fluorinated interface film according to any one of claims 1 to 9.

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