CN113036070A - Negative active film layer and preparation method thereof, pre-lithiation method, negative pole piece and lithium battery - Google Patents
Negative active film layer and preparation method thereof, pre-lithiation method, negative pole piece and lithium battery Download PDFInfo
- Publication number
- CN113036070A CN113036070A CN202110235795.4A CN202110235795A CN113036070A CN 113036070 A CN113036070 A CN 113036070A CN 202110235795 A CN202110235795 A CN 202110235795A CN 113036070 A CN113036070 A CN 113036070A
- Authority
- CN
- China
- Prior art keywords
- layer
- negative electrode
- lithium
- film layer
- active film
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
- H01M4/0402—Methods of deposition of the material
- H01M4/0404—Methods of deposition of the material by coating on electrode collectors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/381—Alkaline or alkaline earth metals elements
- H01M4/382—Lithium
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/582—Halogenides
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
A negative active film layer and a preparation method thereof, a pre-lithiation method, a negative pole piece and a lithium battery belong to the field of batteries. The preparation method of the negative active film layer comprises the following steps: mixing carbon fluoride with molten lithium liquid under a protective atmosphere, coating the mixture on a planar carrier to form a coating, and standing for not less than 2 hours to form a sandwich structure of a carbon fluoride layer-lithium layer in the coating; the mass ratio of the carbon fluoride to the molten lithium liquid is 10 (0.5-1), the chemical formula of the carbon fluoride is CFx, X is more than or equal to 0.5 and less than or equal to 0.99, and the protective atmosphere is used for inhibiting the oxidation of the molten lithium liquid. The preparation method is simple and controllable, the negative active film layer sequentially connected by the CF layer, the LiF layer and the Li layer is formed, and the prelithiation method containing the negative active film layer, the negative pole piece and the lithium battery have excellent primary efficiency, so that the negative pole piece can be kept stable in ambient air for a long time and has excellent primary efficiency.
Description
Technical Field
The application relates to the field of batteries, in particular to a negative active film layer and a preparation method thereof, a pre-lithiation method, a negative pole piece and a lithium battery.
Background
Currently, lithium ion batteries have gradually merged into every part of life as mature energy storage units. In the life, electrical appliances such as mobile phones and notebooks use lithium ion batteries as their energy storage units, and in recent years, lithium ion batteries are also gradually used in power energy storage, such as electric vehicles.
For a lithium ion battery, the most influential factors on its energy density should be the positive electrode material and the negative electrode material. The graphite cathode material of the lithium ion battery used in commercialization at present has lower theoretical capacity, the space for further improving the capacity is very small, and the demand of future high-capacity and long-life electronic equipment cannot be met. The metal and alloy materials are novel high-efficiency lithium storage negative electrode material systems which are researched more in recent years, wherein the silicon-oxygen material is concerned about due to the fact that the silicon-oxygen material has extremely high theoretical specific capacity, but the silicon-oxygen material can form some irreversible capacity byproducts during first charging, and therefore the first efficiency of the battery is far from reaching the application standard.
In order to overcome the defects, the first efficiency of the silicon-oxygen-carbon lithium ion battery is improved by adopting modes such as electrochemical pre-lithium, chemical pre-lithium and the like, but the operation difficulty is high and the safety coefficient is low.
Disclosure of Invention
The application provides a negative active film layer, a preparation method thereof, a pre-lithiation method, a negative pole piece and a lithium battery, which can solve at least one technical problem.
The embodiment of the application is realized as follows:
in a first aspect, the present application provides a method for preparing an anode active film layer, comprising the steps of:
and mixing the carbon fluoride with the molten lithium liquid under a protective atmosphere, coating the mixture on a planar carrier to form a coating, and standing for not less than 2 hours to form a sandwich structure of a carbon fluoride layer-lithium layer in the coating.
Wherein the mass ratio of the carbon fluoride to the molten lithium liquid is 10 (0.5-1), and the chemical formula of the carbon fluoride is CFx, wherein X is more than or equal to 0.5 and less than or equal to 0.99.
The protective atmosphere is used to inhibit oxidation of the molten lithium bath.
The preparation method is simple and controllable, the carbon fluoride and the molten lithium liquid are mixed and then layered due to reasons such as inconsistent weight of the carbon fluoride and the molten lithium liquid, and the carbon fluoride has a low fluorocarbon ratio, so that the carbon fluoride and the molten lithium liquid can perform fluorination reaction to form a lithium fluoride transition layer between a carbon fluoride layer and a lithium layer, and the negative electrode active film layer with a sandwich structure of a CF layer-LiF layer-Li layer is obtained. It is to be understood that the protective atmosphere refers to an atmosphere substantially free of reaction with the molten lithium liquid. The standing process can be carried out under the protection of protective atmosphere, so that oxidation is avoided, and the manufacturing cost is effectively reduced. The cathode active film layer prepared by the preparation method is of a sandwich structure of a CF layer-LiF layer-Li layer, and the CF layer-LiF layer is used as a protective layer for protecting the Li layer, so that the influence of the external environment on the Li layer is prevented, the Li layer can be kept stable for a long time when placed in the air, and the Li layer is prevented from being oxidized; and because the CF layer-LiF layer has better hydrophobicity, the cathode active film layer can have excellent primary efficiency and show excellent electrical property even if the cathode pole piece is exposed in humid atmosphere for 12 hours after being applied to the cathode pole piece.
In a second aspect, the present example provides a negative active film layer including a fluorinated carbon layer, a lithium fluoride layer, and a lithium layer connected in this order.
The negative electrode active film layer is of a sandwich structure of a CF layer-LiF layer-Li layer, and the CF layer-LiF layer is used as a protective layer for protecting the Li layer, so that the influence of the external environment on the Li layer is prevented, the Li layer can be kept stable for a long time when placed in the air, and the Li layer is prevented from being oxidized; and because the CF layer-LiF layer has better hydrophobicity, the cathode active film layer can have excellent first efficiency and show excellent electrical property even if the cathode pole piece is exposed in humid atmosphere after being applied to the cathode pole piece.
In a third aspect, the present examples provide a prelithiation method, comprising:
and mixing the carbon fluoride with the molten lithium liquid under a protective atmosphere, coating the mixture on a current collector to form a coating, and standing for not less than 2 hours to form a sandwich structure of a carbon fluoride layer-lithium layer in the coating.
Wherein the mass ratio of the carbon fluoride to the molten lithium liquid is 10 (0.5-1), and the chemical formula of the carbon fluoride is CFx, wherein X is more than or equal to 0.5 and less than or equal to 0.99.
The protective atmosphere is used to inhibit oxidation of the molten lithium bath.
The preparation method is simple and controllable, and the cathode active film layer with the sandwich structure directly attached to the CF layer, the LiF layer and the Li layer of the cathode active film layer of the current collector is directly obtained. Wherein, the Li layer is attached to the surface of the current collector, and has higher safety compared with lithium powder lithium supplement and lithium foil lithium supplement.
In a fourth aspect, the present application provides a negative electrode sheet, which includes a current collector and a negative electrode active material layer, where the negative electrode active material layer includes the negative electrode active film layer prepared in the embodiments provided in the first aspect of the present application or the negative electrode active film layer provided in the second aspect of the present application, and a lithium layer of the negative electrode active film layer is connected to the current collector.
The cathode plate with the cathode active film layer can show excellent primary efficiency even if exposed in humid atmosphere for 12 hours based on the arrangement of the cathode active film layer.
In a fifth aspect, the present application provides a lithium battery, which includes the negative electrode sheet provided in the fourth aspect of the present application.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
FIG. 1 is a schematic representation of the prelithiation process of the present application;
fig. 2 is a scanning electron microscope image of the negative active film layer provided in example 1;
fig. 3 is a first charge-discharge specific capacity curve diagram of the negative electrode plate placed in a humid environment for different time periods.
Detailed Description
Embodiments of the present application will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present application and should not be construed as limiting the scope of the present application. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The following specifically describes the negative active film layer, the preparation method thereof, the prelithiation method, the negative electrode sheet, and the lithium battery in the embodiment of the present application:
the application actually provides a negative active film layer, and it includes fluorinated carbon layer, lithium fluoride layer and the lithium layer that connects gradually. That is, the negative active film layer has a sandwich structure.
Wherein, carbon fluoride layer, lithium fluoride layer and lithium layer can be based on the independent stack setting of precedence order respectively, but it is active based on lithium fluoride layer and lithium layer nature, therefore preparation technology is comparatively complicated, in order to solve above-mentioned problem, in some embodiments that this application provided, the lithium fluoride layer is by the transition layer that carbon fluoride layer and lithium layer reaction formed, and then effectively simplify the preparation degree of difficulty and technology.
Specifically, the application provides a preparation method of a negative active film layer, which comprises the following steps:
and S1, obtaining the molten lithium liquid.
Since impurities have a large influence on the properties of the finally obtained product, specifically, the molten lithium liquid is obtained in such a manner that: polishing the surface of the lithium foil, removing surface impurities, placing the lithium foil in a melting device protected by inert atmosphere, and heating to melt the lithium foil.
Optionally, the purity of the lithium foil is more than or equal to 99.99%.
Through the setting mode, the interference of impurities contained in the lithium foil is avoided, and meanwhile, because the lithium has active property, the adoption of the melting mode under the inert atmosphere can effectively avoid the influence on the final product performance caused by the reaction of lithium and moisture, oxygen and the like in the air in the melting process to introduce the impurities.
The temperature for heating to melt may be 245 ℃ to 260 ℃, specifically, 245 ℃, 250 ℃, 255 ℃, 257 ℃, or 260 ℃.
And S2, mixing the carbon fluoride and the molten lithium liquid in a protective atmosphere to obtain a mixture.
Wherein the molten lithium liquid and the protective atmosphere are substantially non-reactive.
The protective atmosphere includes, but is not limited to, an inert atmosphere or an argon-hydrogen atmosphere, and may be, for example, O2<0.1ppm and H2O<0.1ppm of a non-inert atmosphere.
In order to avoid the introduction of impurities, carbon fluoride is optionally mixed with the molten lithium liquid under a first protective atmosphere, wherein the first protective atmosphere is an inert atmosphere or an argon-hydrogen atmosphere or the like.
The inert atmosphere includes, but is not limited to argon, and may also be nitrogen, and specifically, for example, argon (purity ≥ 99.99%), the molten lithium liquid is obtained under the inert atmosphere with high purity, and the carbon fluoride and the molten lithium liquid are mixed, so that oxidation of lithium and the like to generate impurities can be effectively avoided, and the performance of the final product can be affected.
The chemical formula of the carbon fluoride is CFx, X is a fluorocarbon ratio, X is more than or equal to 0.5 and less than or equal to 0.99, specifically, for example, X is 0.5, 0.6, 0.7, 0.75, 0.8 or 0.99, and the like, that is, the carbon fluoride is carbon fluoride with a low fluorocarbon ratio, the appropriate fluorocarbon ratio is utilized to ensure that the efficiency and the effect of the subsequent fluorination reaction are good, the lithium fluoride overplate layer can be formed between the carbon fluoride layer and the lithium layer, and the first efficiency of the negative active film layer is improved after the negative active film layer is applied to a negative pole piece.
Alternatively, the average particle size Dv50 of the carbon fluoride is 0.1 μm or less and 0.5 μm or less. Wherein, the carbon fluoride is composed of carbon fluoride particles with different particle sizes, and Dv50 is the particle size which reaches 50% of the volume accumulation from the small particle size side in the volume-based particle size distribution, and the particle size can ensure that the obtained CF layer-LiF layer is loose.
The fluorocarbon can be purchased directly from the market or prepared by itself, and is not limited herein.
Optionally, the carbon fluoride includes one or more of graphite fluoride, fluorinated hard carbon and fluorinated graphene, for example, the carbon fluoride is graphite fluoride, fluorinated hard carbon or fluorinated hard carbon alone, or a mixture of fluorinated hard carbon and fluorinated graphene, and a person skilled in the art may select specific raw materials according to actual needs, which is not limited herein.
Optionally, the purity of the carbon fluoride is 98% and above, thereby avoiding the introduction of impurities.
Optionally, the mass ratio of the carbon fluoride to the molten lithium liquid is 10 (0.5-1), and specifically, the mass ratio of the carbon fluoride to the molten lithium liquid is 10:0.5, 10:0.6, 10:0.7, 10:0.8, 10:0.9, or 10:1, for example. Through the reasonable proportioning of the carbon fluoride and the molten lithium liquid, the finally obtained product is ensured to have better specific capacity and cycling stability.
The mixing step includes, but is not limited to, adding carbon fluoride into the molten lithium liquid for mixing, or adding the molten lithium liquid into the carbon fluoride for mixing, or adding both into a mixing container simultaneously.
To simplify the process and facilitate handling, the carbon fluoride is optionally added directly to the molten lithium liquid in the melting apparatus for mixing.
In order to ensure uniform mixing, optionally, the step of mixing is slowly stirred at a speed of not more than 200rpm, for example, the step of mixing is slowly stirred at a rotation speed of 50rpm, 100rpm, 120rpm, 150rpm, 170rpm, 200rpm, or the like.
And S3, mixing the carbon fluoride with the molten lithium liquid under the protective atmosphere, coating the mixture on a planar carrier to form a coating, and standing for not less than 2 hours to form a sandwich structure of a carbon fluoride layer-lithium layer in the coating.
Wherein the protective atmosphere is used to inhibit oxidation of the molten lithium bath.
The protective atmosphere includes, but is not limited to, an inert atmosphere or an argon-hydrogen atmosphere, and may also be O2<0.1ppm and H2O<0.1ppm of a non-inert atmosphere.
Optionally, the step of mixing the carbon fluoride with the molten lithium liquid under a protective atmosphere, then coating the mixture on a planar carrier, and then standing the planar carrier comprises:
mixing carbon fluoride and molten lithium liquid in a first protective atmosphere, then coating the mixture on a planar carrier, and standing the planar carrier in the first protective atmosphere or a second protective atmosphere.
Wherein the first protective atmosphere is inert atmosphere or argon-hydrogen atmosphere, and the second protective atmosphere is O2<0.1ppm and H2O<0.1ppm of a non-inert atmosphere.
In the standing process, the carbon fluoride floats upwards to form a carbon fluoride layer, and the carbon fluoride layer can avoid the interference reaction of trace water and oxygen directly contacting with lithium, so that the standing can be carried out at O2<0.1ppm and H2O<Standing in a low-oxygen and low-humidity environment with the concentration of 0.1ppm to obtain better performance on the premise of reducing cost and production difficulty.
Alternatively, the mixed carbon fluoride and the molten lithium liquid are left standing for 2h to 5h, for example, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, and the like, and the time is less than the range, so that the fluorination reaction is incomplete, the structure cannot be obtained, and the manufacturing efficiency is reduced if the time exceeds the range.
The material of the planar carrier is not limited.
Optionally, the preparation method further comprises stripping the negative active film layer from the planar carrier according to actual requirements after the standing is completed.
Specifically, for example, when the planar support is a non-current collector, the formed negative electrode active film layer may be peeled off from the planar support, and then the negative electrode active film layer and the current collector are formed together, specifically, the negative electrode active film layer and the current collector are formed together by, for example, pressing, wherein the lithium layer of the negative electrode active film layer is connected with the surface of the current collector.
When the planar carrier is a current collector such as a copper foil, the current collector with the negative active film layer attached thereto is used as a raw material for manufacturing a negative electrode sheet as a whole without being peeled.
In summary, based on the performance of the negative active film layer, the negative active film layer is suitable for being applied to a negative electrode plate, and the inventor finds that the negative active film layer can be directly used as a negative active material and can also be used as a lithium supplement agent for supplementing the SEI film formed by a negative electrode during first charge and discharge and the consumption of a Li source during a circulation process, and the safety performance of the negative electrode plate after pre-lithium in a battery assembly process is improved by the existence of the CF layer-LiF layer, so that the risks of flammability and the like caused by pre-lithium are reduced.
Accordingly, as shown in fig. 1, the present application provides a prelithiation method comprising:
and mixing the carbon fluoride with the molten lithium liquid under a protective atmosphere, coating the mixture on a current collector to form a coating, and standing for not less than 2 hours to form a sandwich structure of a carbon fluoride layer-lithium layer in the coating.
Wherein the mass ratio of the carbon fluoride to the molten lithium liquid is 10 (0.5-1), the chemical formula of the carbon fluoride is CFx, and X is more than or equal to 0.5 and less than or equal to 0.99; the protective atmosphere is used to inhibit oxidation of the molten lithium bath.
For details, reference may be made to a preparation method of the negative active film layer, which is not described herein in detail.
Further, this application provides a negative pole piece, it includes the mass flow body and with negative active material layer, negative active material layer includes above-mentioned negative active film layer, and wherein, the lithium layer of negative active film layer is attached to the mass flow body.
The current collector includes, but is not limited to, a current collector cut into a target shape, and a current collector before cutting.
The negative electrode active material layer may be used not only as a negative electrode active material alone for a negative electrode sheet, but also as a negative electrode active material layer for an existing negative electrode system, that is, the negative electrode active material layer may be composed of only the negative electrode active material layer, or may be composed of the negative electrode active material layer as a lithium supplement and a negative electrode active material.
Optionally, in the negative electrode sheet provided in some specific embodiments of the present application, the negative electrode active material layer is formed by a single negative electrode active film layer, and at this time, the negative electrode active film layer is directly used as the negative electrode active material layer alone.
Alternatively, in another specific example of the present application, the negative electrode active material layer includes a negative electrode active material layer as a lithium supplement agent and a negative electrode material layer made of a negative electrode active material, and the negative electrode active material layer is located between the negative electrode active material layer and the current collector. The negative electrode active material in this case refers to a conventional negative electrode active material, specifically, SiO, CNT, and the like, and is not limited thereto.
At this time, the thickness of the negative electrode active film layer as a lithium supplement agent may be 0.5 to 1.0 μm, for example, the thickness of the negative electrode active film layer is 0.5 μm, 0.6 μm, 0.9 μm, or 1.0 μm, that is, the thickness of the doctor blade is controlled to be 0.5 to 1.0 μm when the doctor blade is applied to the current collector.
In any of the above-described arrangements of the negative electrode sheet, the negative active film layer may be disposed on only one side of the current collector, or may be disposed on both sides of the current collector, and the specific configuration is not limited herein.
The current collector mainly includes, but is not limited to, a foil shape, a mesh shape, and the like, and the material of the current collector includes, but is not limited to, copper.
Generally, when the current collector is in a mesh shape, the negative electrode sheet can be prepared by a first preparation method, which includes: mixing carbon fluoride and molten lithium liquid in a first protective atmosphere, coating the mixture on a planar carrier, standing for at least 2 hours in the first protective atmosphere or a second protective atmosphere, stripping a formed negative active film layer from the planar carrier, laminating and pressing a mesh current collector and the negative active film layer to enable the negative active film layer to be stably attached to the surface of the mesh current collector.
When the current collector is in a foil shape, the negative electrode plate can adopt the first preparation mode or the second preparation mode, wherein the second preparation mode comprises the following steps: the surface of the current collector is pre-treated to obtain the current collector with a negative active film layer, and then the slurry forming the negative active material layer is coated on the surface of the negative active film layer and dried. The preparation method is simple to operate, ensures the uniformity of the pre-lithiation and further improves the safety.
Finally, the application provides a lithium battery, which comprises the negative pole piece.
The lithium battery includes any one of a lithium metal battery and a lithium ion battery, and is not limited herein.
The negative active film layer, the preparation method thereof, the prelithiation method, the negative electrode sheet and the lithium battery of the present application are further described in detail with reference to the following examples.
Example 1
S1, polishing the surface of a lithium foil, placing the lithium foil in a melting device protected by argon (the purity is more than or equal to 99.99 percent), and heating to 250 ℃ to obtain molten lithium liquid.
S2, slowly adding graphite fluoride powder into liquid molten lithium at the rotating speed of 150rpm, slowly stirring to fully mix the graphite fluoride powder, pouring out the lithium fluoride powder, blade-coating the graphite fluoride powder on the upper surface of a copper foil with the thickness of 8 mu m by using a four-side scraper, blade-coating the graphite fluoride powder with the thickness of 1.5 mu m, and placing the copper foil on O2<0.1ppm and H2O<And standing for 5 hours in the environment of 0.1ppm to form a negative electrode active film layer on the surface of the copper foil as a pre-lithiation stable lithium-coated copper foil.
As shown in fig. 2, the scanning electron microscope image of the negative active film layer shows that the negative active film layer is a sandwich structure of CF layer-LiF layer-Li layer.
The Li layer in the negative active film layer is connected with the surface of the copper foil, the mass ratio of the graphite fluoride powder to the liquid molten lithium is 0.5:10, and the particle size and the fluorocarbon ratio of the graphite fluoride powder are shown in Table 1.
Example 2
S1, polishing the surface of a lithium foil, placing the lithium foil in a melting device protected by argon (the purity is more than or equal to 99.99 percent), and heating to 250 ℃ to obtain molten lithium liquid.
S2, slowly adding graphite fluoride powder into liquid molten lithium at the rotating speed of 150rpm, slowly stirring to fully mix the graphite fluoride powder, pouring out the lithium fluoride powder, blade-coating the graphite fluoride powder on the upper surface of a copper foil with the thickness of 8 mu m by using a four-side scraper, blade-coating the graphite fluoride powder with the thickness of 0.5 mu m, and placing the copper foil on O2<0.1ppm and H2O<And standing for 5 hours in the environment of 0.1ppm to form a uniform negative electrode active film layer of a CF layer-LiF layer-Li layer on the surface of the copper foil, wherein the negative electrode active film layer is used as a pre-lithiation stable lithium-coated copper foil.
The Li layer in the negative active film layer is connected with the surface of the copper foil, the mass ratio of the graphite fluoride powder to the liquid molten lithium is 1:10, and the particle size and the fluorocarbon ratio of the graphite fluoride powder are shown in Table 1.
Example 3
S1, polishing the surface of a lithium foil, placing the lithium foil in a melting device protected by argon (the purity is more than or equal to 99.99 percent), and heating to 250 ℃ to obtain molten lithium liquid.
S2, slowly adding graphite fluoride powder into liquid molten lithium at the rotating speed of 100rpm, slowly stirring to fully mix the graphite fluoride powder, pouring out the lithium fluoride powder, blade-coating the graphite fluoride powder on the upper surface of a copper foil with the thickness of 8 mu m by using a four-side scraper, wherein the blade-coating thickness is 1.0 mu m, and placing the copper foil on O2<0.1ppm and H2O<And standing for 5 hours in the environment of 0.1ppm to form a uniform negative electrode active film layer of a CF layer-LiF layer-Li layer on the surface of the copper foil, wherein the negative electrode active film layer is used as a pre-lithiation stable lithium-coated copper foil.
The Li layer in the negative active film layer is connected with the surface of the copper foil, the mass ratio of the graphite fluoride powder to the liquid molten lithium is 0.7:10, and the particle size and the fluorocarbon ratio of the graphite fluoride powder are shown in Table 1.
Example 4
It differs from example 1 only in that it replaces graphite fluoride powder with hard carbon fluoride. Wherein the average particle diameter Dv50 of the fluorinated hard carbon is 0.5 μm, and the fluorine-carbon ratio of the fluorinated hard carbon is 0.6. And preparing the pre-lithiation stable lithium-coated copper foil in the same way.
Comparative example 1
According to the weight ratio of SiO: PVDF: CNT: NMP 96%: 3%: 1%: after 10% homogenization, the mixture is coated on the upper surface of an untreated copper foil, the coating thickness is 90 mu m, and the mixture is dried and rolled to be used as a negative pole piece.
Comparative example 2
It differs from example 1 only in that the fluorine-carbon ratio in the graphite fluoride powder was 0.45, and a prelithiation-stable lithium-coated copper foil was produced in the same manner.
Comparative example 3
It differs from example 1 only in that the fluorine to carbon ratio in the graphite fluoride powder was 1, and a prelithiation-stable lithium-coated copper foil was produced in the same manner.
Comparative example 4
The difference from example 1 is only that, in step S2, the mass ratio of graphite fluoride powder to liquid molten lithium was 1.1:10, and a prelithiation-stable lithium-coated copper foil was produced in the same manner.
Comparative example 5
The difference from example 1 is only that, in step S2, the mass ratio of graphite fluoride powder to liquid molten lithium was 0.4:10, and a prelithiation-stable lithium-coated copper foil was produced in the same manner.
Test example 1
Cutting the pre-lithiation stable lithium-coated copper foils obtained in the examples 1-4 and the comparative examples 2-5 to obtain negative pole piece substrates with the same size corresponding to the examples and the comparative examples, and performing the following steps according to the ratio of SiO: PVDF: CNT: NMP 96%: 3%: 1%: the 10% homogenate was coated on the surface of the negative active film layer of each negative pole piece substrate, the thickness of the blade coating was 90 μm, and the drying and rolling were performed to obtain negative pole pieces corresponding to each example and comparative example.
Assembling the 8Ah soft package battery: negative pole piece: the negative electrode pieces obtained in examples 1 to 4 and comparative examples 1 to 5; electrolyte solution: LiPF 6: EC: DEC: PP: FEC ═ 1:1.78:3.57:1.4: 8; and (3) anode proportioning: NCM: SP: PVDF 97:1.0: 2.0.
The charge and discharge test was performed under test conditions of a voltage range of 2.75 to 4.25V and a current density of 0.5C to obtain electrochemical properties of each cell, and the cycle performance of each cell was tested.
The test method of the cycle performance comprises the following steps: the environment temperature is 25 ℃, the test voltage range is 2.75V-4.2V, and the following steps are carried out: (1) standing for 10 min; (2) charging to 4.2V at a constant current of 0.5C and constant voltage to 0.05C; (3) standing for 30 min; (4) discharging to 2.75V at constant current of 0.5C; (5) and (5) repeating the steps (2) to (4) and circulating for 50 weeks.
The electrochemical performance and cycle performance test results of the above-described each pouch cell obtained in correspondence to examples 1 to 4 and comparative examples 1 to 5 are shown in table 1 below.
TABLE 1 test results
According to table 1, it can be found that the first charge capacity of the pouch battery assembled in examples 1 to 4 is lower than that of the pouch battery corresponding to comparative example 1, that is, in the lithium intercalation process, excessive lithium participates in the intercalation of the negative active material, and the active lithium ion content in the battery is increased; the first discharge capacity of the batteries assembled in examples 1 to 4 is higher than that of comparative example 1, which means that the batteries assembled in examples 1 to 4 do not consume a large amount of active lithium ions and can extract more Li + when the SEI film is generated. That is, the negative electrode active film layer can be used as a lithium supplement agent, so that the first charge-discharge efficiency of the lithium battery is effectively improved, and the capacity exertion of the negative electrode active film layer in the negative electrode plate cannot be influenced by the existence of the CF layer-LiF layer.
From table 1, it can be seen that although the first efficiency of comparative examples 2 to 3 is equivalent to that of example 1, the 50-week cycle capacity thereof is significantly reduced, indicating that the anode active film layer provided in the present application cannot be obtained after the fluorocarbon ratio is out of the range of the present application.
From table 1, it can be seen that the first efficiency and 50-week cycle capacity of the assembled batteries of comparative example 4 and comparative example 5 are reduced compared to example 1, indicating that the present application adopts reasonable raw material ratio to make them have better electrochemical performance and cycle performance.
To sum up, after the negative active film layer prepared by the embodiment of the application is used for the negative pole piece, the first efficiency and the discharge capacity of the battery can be improved, and the energy density of the battery can be improved.
Test example 2
The prelithiation stable lithium-coated copper foil prepared in example 2 was exposed to an environment with a relative humidity of 40%, and when exposure times of 0h, 4h, 8h, and 12h were selected, the same size prelithiation stable lithium-coated copper foil was cut out as a negative electrode sheet, and then a counter electrode was used as a plain copper foil and a separator was used as a PE base film, and a primary charge/discharge test was performed at a charge/discharge rate of 0.02C and a test voltage of 0.05V to 2.5V, and the result is shown in fig. 3.
According to fig. 3, no matter the cathode pole piece prepared by placing the pre-lithiation stabilized lithium-coated copper foil in the air with the relative humidity of 40% for 4h, 8h or 12h, the change of the charging and discharging specific capacity of the cathode pole piece is extremely small compared with the cathode pole piece (namely, Fresh in fig. 3) prepared by placing the pre-lithiation stabilized lithium-coated copper foil with the time of 0, and the change is basically kept unchanged.
That is, due to the existence of the negative electrode active film layer, the pre-lithiation stable lithium-coated copper foil can be stably placed in the air with the humidity of 40% for a long time, and the prepared negative electrode has the gram capacity close to that of a negative electrode piece prepared by the pre-lithiation stable lithium-coated copper foil which is not exposed in a high-humidity environment, and has the same specific capacity and cycling stability, which indicates that the negative electrode active film layer can stably exist in the environment with the relative humidity of 40%.
The above test example 2 was repeated by taking examples 1, 3 and 4 as examples, and similar results were obtained.
That is, the negative electrode sheet provided by the present application can be stable even when exposed to high-humidity air, based on the presence of the negative active film layer, and has excellent primary efficiency.
In conclusion, the negative active film layer, the negative pole piece containing the negative active film layer and the lithium ion battery provided by the application have excellent primary efficiency, the lithium layer in the negative active film layer can be kept stable in ambient air for a long time and is prevented from being oxidized, and meanwhile, the negative active film layer can have excellent primary efficiency and show excellent electrical property even if being exposed in humid atmosphere with the relative humidity of 40% for 12 hours, and compared with the existing lithium supplementing mode, the negative active film layer has higher safety, the preparation method of the negative active film layer is simple and controllable, and the processing difficulty is small.
The foregoing is merely exemplary of the present application and is not intended to limit the present application, which may be modified or varied by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. A preparation method of a negative electrode active film layer is characterized by comprising the following steps:
mixing carbon fluoride with molten lithium liquid under a protective atmosphere, coating the mixture on a planar carrier to form a coating, and standing for not less than 2 hours to form a sandwich structure of a carbon fluoride layer-lithium layer in the coating;
wherein the mass ratio of the carbon fluoride to the molten lithium liquid is 10 (0.5-1), the chemical formula of the carbon fluoride is CFx, and X is more than or equal to 0.5 and less than or equal to 0.99;
the protective atmosphere is used to inhibit oxidation of the molten lithium bath.
2. The method of claim 1, wherein the step of mixing carbon fluoride with molten lithium solution under a protective atmosphere, applying the mixture to a flat support to form a coating layer, and standing for not less than 2 hours comprises:
mixing the carbon fluoride and the molten lithium liquid in a first protective atmosphere, then coating the mixture on a planar carrier, and standing the planar carrier in the first protective atmosphere or a second protective atmosphere;
wherein the first protective atmosphere is an inert atmosphere or an argon-hydrogen atmosphere;
the second protective atmosphere is O2<0.1ppm and H2O<0.1ppm of a non-inert atmosphere.
3. The production method according to claim 1 or 2, wherein 0.1 μm or less of the average particle diameter Dv50 or less is 0.5 μm or less of the fluorinated carbon;
optionally, the fluorinated carbon comprises one or more of graphite fluoride, fluorinated hard carbon, and fluorinated graphene;
optionally, the purity of the carbon fluoride is 98% and above.
4. The production method according to claim 1 or 2, characterized in that the mixed carbon fluoride and the molten lithium liquid are left to stand for 2 to 5 hours;
optionally, the step of mixing is with stirring at a speed of no more than 200 rpm.
5. The negative electrode active film layer is characterized by comprising a carbon fluoride layer, a lithium fluoride layer and a lithium layer which are sequentially connected.
6. A prelithiation method, comprising:
mixing carbon fluoride with molten lithium liquid under a protective atmosphere, coating the mixture on a current collector to form a coating, and standing for not less than 2 hours to form a sandwich structure of a carbon fluoride layer-lithium layer in the coating;
wherein the mass ratio of the carbon fluoride to the molten lithium liquid is 10 (0.5-1), the chemical formula of the carbon fluoride is CFx, and X is more than or equal to 0.5 and less than or equal to 0.99;
the protective atmosphere is used to inhibit oxidation of the molten lithium bath.
7. A negative electrode sheet comprising a current collector and a negative electrode active material layer, wherein the negative electrode active material layer comprises the negative electrode active film layer prepared by the preparation method according to any one of claims 1 to 4 or the negative electrode active film layer according to claim 5, and a lithium layer of the negative electrode active film layer is attached to the current collector.
8. The negative electrode tab according to claim 7, wherein the negative electrode active material layer is composed of a single layer of the negative electrode active film layer.
9. The negative electrode sheet according to claim 7, wherein the negative electrode active material layer includes the negative electrode active film layer as a lithium replenishing agent and a negative electrode material layer composed of a negative electrode active material, the negative electrode active film layer being located between the negative electrode active material layer and the current collector;
optionally, the thickness of the negative active film layer is 0.5-1.0 μm.
10. A lithium battery comprising the negative electrode tab of any one of claims 7 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110235795.4A CN113036070A (en) | 2021-03-03 | 2021-03-03 | Negative active film layer and preparation method thereof, pre-lithiation method, negative pole piece and lithium battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110235795.4A CN113036070A (en) | 2021-03-03 | 2021-03-03 | Negative active film layer and preparation method thereof, pre-lithiation method, negative pole piece and lithium battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113036070A true CN113036070A (en) | 2021-06-25 |
Family
ID=76466018
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110235795.4A Pending CN113036070A (en) | 2021-03-03 | 2021-03-03 | Negative active film layer and preparation method thereof, pre-lithiation method, negative pole piece and lithium battery |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113036070A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113571700A (en) * | 2021-07-22 | 2021-10-29 | 惠州亿纬锂能股份有限公司 | Composite carbon fluoride electrode and preparation method and application thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108461724A (en) * | 2018-03-05 | 2018-08-28 | 苏州大学 | A kind of preparation method of high security metal composite negative pole |
| CN108886150A (en) * | 2017-01-16 | 2018-11-23 | 株式会社Lg化学 | The manufacturing method of secondary battery cathode and the cathode comprising lithium metal layer and its protective layer with fine pattern |
| CN109671908A (en) * | 2018-12-17 | 2019-04-23 | 深圳先进技术研究院 | Metal lithium electrode and preparation method thereof, lithium battery |
| US20190379056A1 (en) * | 2018-06-07 | 2019-12-12 | Lin Chen | Materials and methods for components of lithium batteries |
| CN110828778A (en) * | 2019-10-30 | 2020-02-21 | 复阳固态储能科技(溧阳)有限公司 | Pre-lithiation cathode with sandwich structure and lithium ion battery |
-
2021
- 2021-03-03 CN CN202110235795.4A patent/CN113036070A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108886150A (en) * | 2017-01-16 | 2018-11-23 | 株式会社Lg化学 | The manufacturing method of secondary battery cathode and the cathode comprising lithium metal layer and its protective layer with fine pattern |
| CN108461724A (en) * | 2018-03-05 | 2018-08-28 | 苏州大学 | A kind of preparation method of high security metal composite negative pole |
| US20190379056A1 (en) * | 2018-06-07 | 2019-12-12 | Lin Chen | Materials and methods for components of lithium batteries |
| CN109671908A (en) * | 2018-12-17 | 2019-04-23 | 深圳先进技术研究院 | Metal lithium electrode and preparation method thereof, lithium battery |
| CN110828778A (en) * | 2019-10-30 | 2020-02-21 | 复阳固态储能科技(溧阳)有限公司 | Pre-lithiation cathode with sandwich structure and lithium ion battery |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113571700A (en) * | 2021-07-22 | 2021-10-29 | 惠州亿纬锂能股份有限公司 | Composite carbon fluoride electrode and preparation method and application thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Zhang et al. | A facile annealing strategy for achieving in situ controllable Cu 2 O nanoparticle decorated copper foil as a current collector for stable lithium metal anodes | |
| CN105633360B (en) | Amorphous state ferroso-ferric oxide/graphene aerogel composite, preparation method and applications | |
| CN109950476A (en) | A kind of lithium anode material and its preparation method and application | |
| CN111517374B (en) | Fe7S8Preparation method of/C composite material | |
| CN108468042A (en) | A kind of method that fluorinated ethylene carbonate handles lithium metal and its application in solid state battery | |
| CN107565088B (en) | Preparation method of negative electrode of lithium metal secondary battery | |
| CN107431204A (en) | Sodium ion and kalium ion battery anode | |
| CN113161602A (en) | Lithium ion battery cell, lithium ion battery and preparation method | |
| KR20140108380A (en) | Secondary battery including silicon-metal alloy-based negative active material | |
| Chen et al. | Reactivating dead Li by shuttle effect for high-performance anode-free Li metal batteries | |
| CN109244370B (en) | Preparation method of secondary lithium metal battery cathode steam protective film | |
| CN112349875B (en) | Lithium ion battery copper-copper oxide integrated cathode based on hollow tubular three-dimensional nano porous structure and preparation method | |
| CN114141992A (en) | Self-propagating alloyed lithium negative electrode and preparation method thereof | |
| CN114242961A (en) | Graphene/silicon oxide-coated nano-silicon composite material, and preparation method and application thereof | |
| CN112103499B (en) | Graphene-based negative electrode material and preparation method thereof | |
| CN115411351A (en) | Solid-state battery modified by ion/electron mixed conductive solid interface layer and preparation method thereof | |
| CN113036070A (en) | Negative active film layer and preparation method thereof, pre-lithiation method, negative pole piece and lithium battery | |
| CN108987673B (en) | Lithium negative electrode containing conductive protection film and preparation method and application thereof | |
| CN116470003A (en) | Pre-lithiated negative electrode piece and lithium ion battery | |
| CN115810710A (en) | Surface modification method for lithium alloy negative electrode of primary lithium battery | |
| CN111653724B (en) | Surface-modified lithium nickel manganese oxide positive electrode material and preparation method thereof | |
| CN114937809A (en) | Organic electrolyte with low freezing point and sodium ion battery using same | |
| CN113451547A (en) | Composite metal lithium cathode and lithium ion battery comprising same | |
| CN113422001A (en) | Negative electrode prelithiation additive and preparation method and application thereof | |
| CN116230946B (en) | Composite lithium electrode material and preparation method and application thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20210625 |