CN117096281B - Composite electrode plate, preparation method thereof and lithium ion battery - Google Patents

Composite electrode plate, preparation method thereof and lithium ion battery Download PDF

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Publication number
CN117096281B
CN117096281B CN202311321320.2A CN202311321320A CN117096281B CN 117096281 B CN117096281 B CN 117096281B CN 202311321320 A CN202311321320 A CN 202311321320A CN 117096281 B CN117096281 B CN 117096281B
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electrode film
mixture
polyvinylidene fluoride
film
solid electrolyte
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CN117096281A (en
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周柯
杜孝龙
宋赏
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Suzhou Qingtao New Energy S&T Co Ltd
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Suzhou Qingtao New Energy S&T Co Ltd
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    • 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
    • H01M4/139—Processes of manufacture
    • 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
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M10/058—Construction or manufacture
    • 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
    • H01M4/0407—Methods of deposition of the material by coating on an electrolyte layer
    • 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
    • H01M4/043—Processes of manufacture in general involving compressing or compaction
    • 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
    • H01M4/043—Processes of manufacture in general involving compressing or compaction
    • H01M4/0435—Rolling or calendering

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The application relates to a composite electrode plate, a preparation method thereof and a lithium ion battery. The preparation method comprises the following steps: mixing the active material, the conductive agent and the binder to prepare a mixture; carrying out fibrosis treatment on the mixture to obtain a fibrosis mixture; calendaring the fiberized mixture to obtain a primary electrode film; setting polyvinylidene fluoride on one side surface of the primary electrode film to prepare an electrode film containing a polyvinylidene fluoride layer; the binder comprises polytetrafluoroethylene; dry-process compounding the electrode film and the solid electrolyte film, and attaching the solid electrolyte film to the polyvinylidene fluoride layer in the electrode film; and obtaining the composite electrode plate. According to the polyvinylidene fluoride electrode film, the polyvinylidene fluoride layer is arranged on the surface of the primary electrode film, the electrode film containing the polyvinylidene fluoride layer is prepared, and due to the fact that the PVDF melting point is low, good bonding effect can be achieved when the electrode film and the solid electrolyte film are compounded, the lamination is tighter, and meanwhile the cycle performance of the battery is better.

Description

Composite electrode plate, preparation method thereof and lithium ion battery
Technical Field
The application relates to the technical field of batteries, in particular to a composite electrode plate, a preparation method thereof and a lithium ion battery.
Background
The lithium ion battery has the advantages of high energy density, wide working temperature range, long cycle life, capability of rapid charge and discharge and the like, and is widely applied to the fields of mobile phones, computers, electric automobiles and the like. However, the safety problem of lithium ion batteries is still receiving a great deal of attention, and the existing researches prove that the ceramic layer coated on the surface of the electrode plate, especially the positive electrode plate with higher nickel content, is helpful for improving the safety performance of the batteries, but at present, most of the lithium ion batteries are coated on the surface of the electrode plate by a wet coating method to compound a solid electrolyte membrane. The presence of the solvent necessary for wet coating not only causes environmental pollution but also affects battery performance, and some of the novel solid electrolyte materials such as halide solid electrolytes are sensitive to some solvents, and wet processes are not applicable to all electrolyte materials.
The dry process is a film forming process which is emerging at present, and is reported in the preparation of electrodes. In the dry electrode preparation process, firstly, active materials, conductive materials, binders and the like are combined into mixed powder, the mixed powder is extruded and rolled after being fiberized to form a continuous self-supporting dry coating, and the coating is pressed with a current collector to form an electrode plate. The dry electrode preparation process is simple and environment-friendly, and the recycling service life of the product is prolonged while the energy consumption process of the product is reduced. However, the degree of adhesion between the electrode sheet and the solid electrolyte membrane, which is produced by the conventional dry process, needs to be further improved.
Disclosure of Invention
Based on the above, the application provides a composite electrode plate, a preparation method thereof and a lithium ion battery to solve the technical problems.
The first aspect of the application provides a preparation method of a composite electrode slice, which comprises the following steps:
s1, preparing an electrode film:
s1-1, mixing an active material, a conductive agent and a binder to prepare a mixture;
s1-2, carrying out fibrosis treatment on the mixture to obtain a fibrosis mixture;
s1-3, carrying out calendaring treatment on the fiberizing mixture to obtain a primary electrode film;
s1-4, setting polyvinylidene fluoride on one side surface of the primary electrode film to prepare an electrode film containing a polyvinylidene fluoride layer;
the binder comprises polytetrafluoroethylene;
s2, carrying out dry-process compounding on the electrode film prepared in the step S1 and a solid electrolyte film, and attaching the solid electrolyte film to a polyvinylidene fluoride layer in the electrode film; and
and S3, obtaining the composite electrode pole piece.
In some embodiments, in step S1-2, the manner of the fiberizing treatment comprises at least one of air milling, mechanical stirring, shearing by a shearing machine, mechanical fusing, twin screw extrusion.
In some embodiments, in step S2, the electrode film and the solid electrolyte film are dry-compounded using an elastic roller.
In some embodiments, in step S2, the pressing temperature is 80 ℃ to 160 ℃ during the dry lamination process.
In some embodiments, the active material, the conductive agent, and the binder are 85% -98%, 1% -10% by mass, respectively, in the mixture.
In some embodiments, the polyvinylidene fluoride layer has a thickness of 1 μm to 10 μm.
In some embodiments, the polyvinylidene fluoride layer has a thickness of 1 μm to 5 μm.
In some embodiments, the thickness of the composite electrode sheet is 50 μm to 500 μm.
A second aspect of the present application provides a composite electrode sheet manufactured according to the manufacturing method provided in the first aspect.
A third aspect of the present application provides a lithium ion battery comprising a composite electrode sheet manufactured according to the manufacturing method provided in the first aspect above.
According to the method, the polyvinylidene fluoride is arranged on the surface of one side of the primary electrode film, the electrode film containing the polyvinylidene fluoride layer is prepared, the electrode film and the solid electrolyte film are subjected to dry-process compounding, the solid electrolyte film is attached to the polyvinylidene fluoride layer in the electrode film, and finally the composite electrode plate is prepared. Because the self-adhesiveness of the polyvinylidene fluoride is excellent, when the electrode film with the polyvinylidene fluoride layer is compounded with the solid electrolyte film in the process of preparing the battery, the lamination between the electrode film and the solid electrolyte film is more compact, and the lamination effect is better.
Drawings
Fig. 1 is a flowchart of a method for preparing a composite electrode sheet according to an embodiment of the present application.
Detailed Description
Reference will now be made in detail to the implementations of the application, one or more examples of which are described below. Each example is provided by way of explanation, not limitation, of the present application. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the scope or spirit of the present application. For example, features illustrated or described as part of one embodiment can be used on another embodiment to yield still a further embodiment.
Accordingly, it is intended that the present application cover such modifications and variations as fall within the scope of the appended claims and their equivalents. Other objects, features and aspects of the present application are disclosed in or are apparent from the following detailed description. It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present application.
In the present application, the technical features described in an open manner include a closed technical scheme composed of the listed features, and also include an open technical scheme including the listed features.
In the present application, reference is made to numerical intervals, where the numerical intervals are considered to be continuous unless specifically stated, and include the minimum and maximum values of the range, and each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values of the range is included. Further, when multiple range description features or characteristics are provided, the ranges may be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to include any and all subranges subsumed therein.
In this context, referring to units of data range, if a unit is only carried after the right endpoint, the units representing the left and right endpoints are identical. For example, 100 to 150 nm means that the units of the left end point "100" and the right end point "150" are nm (nanometers).
All embodiments and alternative embodiments of the present application may be combined with each other to form new solutions, unless specifically stated otherwise.
All technical features and optional technical features of the present application may be combined with each other to form new technical solutions, unless specified otherwise.
All steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise indicated. For example, the method comprises steps (a) and (b), meaning that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, it is mentioned that the method may further comprise step (c), meaning that step (c) may be added to the method in any order, e.g. the method may comprise steps (a), (b) and (c), may also comprise steps (a), (c) and (b), may also comprise steps (c), (a) and (b), etc.
Reference herein to "comprising" and "including" means open ended, as well as closed ended, unless otherwise noted. For example, the terms "comprising" and "comprises" may mean that other components not listed may be included or included, or that only listed components may be included or included.
The term "or" is inclusive in this application, unless otherwise specified. For example, the phrase "a or B" means "a, B, or both a and B. More specifically, either of the following conditions satisfies the condition "a or B": a is true (or present) and B is false (or absent); a is false (or absent) and B is true (or present); or both A and B are true (or present).
As shown in fig. 1, a first aspect of the present application provides a method for preparing a composite electrode sheet, including the following steps:
s1: preparation of electrode film:
s1-1, mixing an active material, a conductive agent and a binder to prepare a mixture;
s1-2, carrying out fibrosis treatment on the mixture to obtain a fibrosis mixture;
s1-3, carrying out calendaring treatment on the fiberizing mixture to obtain a primary electrode film;
s1-4, spraying polyvinylidene fluoride on one side surface of the primary electrode film to prepare an electrode film containing a polyvinylidene fluoride layer;
wherein the binder comprises Polytetrafluoroethylene (PTFE);
s2, carrying out dry-process compounding on the electrode film prepared in the step S1 and a solid electrolyte film, and attaching the solid electrolyte film to a polyvinylidene fluoride layer in the electrode film; and
and S3, obtaining the composite electrode pole piece.
In step S1-1, the mass percentage of the active materials in the mixture is 85% -98%, including but not limited to 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%. Preferably, the mass percentage of the active materials in the mixture is 90% -98%.
It is understood that the active material in the present application may be a positive electrode active material or a negative electrode active material.
In the present application, the types of the positive electrode active material and the negative electrode active material are not particularly limited, and any known positive electrode active material and negative electrode active material can be used in the present application without departing from the inventive concept of the present application. The following description of the positive electrode active material and the negative electrode active material is merely illustrative, and is not intended to limit the scope of protection.
In some of these embodiments, the positive electrode active material includes, but is not limited to, lithium cobalt oxide (LiCoO) 2 ) Lithium nickel cobalt manganate (LiNi) x Mn y Co 1-x-y O 2 NMC for short), lithium nickel cobalt aluminate (LiNiCoAlO 2 Abbreviated as NCA), lithium manganate (LiMn 2 O 4 ) Lithium iron manganese phosphate (LiMn) x Fe 1-x PO 4 Abbreviated as LMFP), lithium vanadium phosphate (Li 3 V 2 (PO 4 ) 3 ) Lithium vanadyl phosphate (LiVOPO) 4 ) Lithium iron phosphate (LiFePO) 4 ) Lithium titanate (Li) 2 TiO 3 ) And one or more of lithium-rich manganese-based materials.
In some of these embodiments, the negative electrode active material includes, but is not limited to, artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, lithium titanate (Li 2 TiO 3 ) Tin baseOne or more of the materials.
In the step S1-1, the mass percentage of the conductive agent in the mixture is 1% -10%, including but not limited to 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%. Preferably, the mass percentage of the conductive agent in the mixture is 2% -5%.
In the present application, the kind of the conductive agent is not particularly limited, and any known conductive agent can be used in the present application without departing from the inventive concept of the present application. The following description of the conductive agent is merely illustrative, and not intended to limit the scope of protection.
In some of these embodiments, the conductive agent includes, but is not limited to, one or more of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, carbon nanofibers, and graphene.
In step S1, the mass percentage of the binder in the mixture is 1% -10%, including but not limited to 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%. Preferably, the mass percentage of the binder in the mixture is 2% -5%.
In step S1-1, the active material, the conductive agent and the binder may be mixed by ball milling, air-flow mixing or pulverizing, and the mixing method is not particularly limited in this application, and any known mixing method may be used in this application without departing from the inventive concept of this application.
In step S1-2, the mixture is subjected to a fiberizing treatment in a manner including at least one of air-jet milling, mechanical stirring, shearing by a shearing machine, mechanical fusion and twin-screw extrusion.
Further, in step S1-2, the mixture is subjected to a fiberizing treatment using a high-speed shearing machine.
In some embodiments, in the step of preparing the fiberizing mixture, a high-speed shearing machine is adopted to carry out fiberizing treatment under the condition that the rotating speed is 20000 r/min-28000 r/min. Preferably, the fiberizing treatment is carried out by adopting a high-speed shearing machine under the condition that the rotating speed is 22000 r/min-26000 r/min. More preferably, the fiberizing treatment is performed using a high speed shear at a rotational speed of 25000 r/min.
Under the action of high shearing force, polytetrafluoroethylene (PTFE) in the adhesive is converted from a powder state to a fibrous state and is uniformly distributed among particles of other components of the electrode, so that a fiber network structure is formed, a required self-supporting structure is provided for various components in the solid electrolyte membrane, and meanwhile, a rich channel is provided for rapid migration of free lithium ions in the solid electrolyte membrane.
In step S1-3, the fiberizing mixture may be calendared using a pair roll device and/or a flat plate device. Further, the fibrillated mixture may be subjected to a heat calendering process using a twin roll apparatus.
In some of these embodiments, the temperature of the twin roll apparatus is from 60 ℃ to 160 ℃, including, but not limited to, 60 ℃, 70 ℃, 80 ℃, 90 ℃,100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃. Preferably, the temperature of the twin roll apparatus is from 110 ℃ to 130 ℃.
In step S1-4, polyvinylidene fluoride (PVDF) is provided on one side surface of the primary electrode film to prepare an electrode film containing a polyvinylidene fluoride layer.
In some embodiments, polyvinylidene fluoride may be provided on one side surface of the primary electrode film in a coating manner.
In some embodiments, polyvinylidene fluoride is also disposed on one side surface of the primary electrode film by dry electrostatic spraying.
Specifically, polyvinylidene fluoride powder was charged into a powder feeder, and the powder was sprayed on one side surface of the primary electrode film using a dry coater.
It is understood that the side surface of the primary electrode film on which polyvinylidene fluoride powder is sprayed in the present application refers to the side surface of the primary electrode film facing the solid electrolyte membrane.
In some embodiments, polyvinylidene fluoride (PVDF) powder is sprayed on one side surface of the primary electrode film, and the polyvinylidene fluoride powder is vertically sprayed on the primary electrode film arranged on a spraying equipment receiving device under the acceleration of 100kPa nitrogen, wherein the spraying voltage is 23kV, the receiving distance is 10cm, and the spraying time is 3min, so that the electrode film containing the polyvinylidene fluoride layer is finally obtained.
In step S2, the electrode film and the solid electrolyte film are dry-compounded using an elastic roller. The elastic roller comprises a rigid roller and an elastic piece, and the elastic piece is coated on the outer side of the rigid roller. In the rolling process of the electrode film and the solid electrolyte by adopting the elastic roller, the buffer provided by the elastic piece in the elastic roller enables the solid electrolyte film to better cover the electrode film.
In some embodiments, in step S2, when the electrode film and the solid electrolyte film are subjected to dry lamination, a heating process is further included, and the heated electrode film and the heated solid electrolyte film are softened compared with those before heating, so that ductility of the electrode film and the solid electrolyte film is improved, occlusion between the electrode film and the solid electrolyte film is tighter, bonding strength is stronger, and lamination effect is better.
Specifically, in the dry compounding process, the lamination temperature is 60 ℃ to 160 ℃, including but not limited to 60 ℃, 70 ℃, 80 ℃, 90 ℃,100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃ and 160 ℃.
In some of these embodiments, the polyvinylidene fluoride layer in the electrode film has a thickness of 1 μm to 10 μm, including but not limited to 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm. Preferably, the thickness of the polyvinylidene fluoride layer in the electrode film is 1 μm to 5 μm.
In some of these embodiments, the composite electrode sheet has a thickness of 50 μm to 500 μm, including but not limited to 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm.
According to the method, the polyvinylidene fluoride is arranged on the surface of one side of the primary electrode film, the electrode film containing the polyvinylidene fluoride layer is prepared, the electrode film and the solid electrolyte film are subjected to dry-process compounding, the solid electrolyte film is attached to the polyvinylidene fluoride layer in the electrode film, and finally the composite electrode plate is prepared. Because the self-adhesiveness of the polyvinylidene fluoride is excellent, when the electrode film with the polyvinylidene fluoride layer is compounded with the solid electrolyte film in the process of preparing the battery, the lamination between the electrode film and the solid electrolyte film is more compact, and the lamination effect is better.
When the polyvinylidene fluoride is electrostatically sprayed by a dry method, the whole production process is simple, water or an organic solvent is not needed, the environment is more friendly, and the recycling service life of the product is prolonged while the energy consumption process of the product is reduced.
The second aspect of the application provides a composite electrode slice, which is prepared according to the preparation method provided by the first aspect.
It is understood that in this application, the composite electrode sheet may be a composite positive electrode sheet and/or a composite negative electrode sheet.
A third aspect of the present application provides a lithium ion battery, which includes a composite electrode sheet prepared by the preparation method provided in the first aspect.
The present application will be further described with reference to specific examples and comparative examples.
Example 1
Preparing a composite positive plate:
according to the mass percentages of the positive electrode active material lithium manganate, the conductive agent ketjen black and the binder polytetrafluoroethylene in the mixture, respectively weighing 96%, 2% and 2%, and mixing by an airflow pulverizer to obtain the mixture.
And (3) carrying out fiberizing treatment on the mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain the fiberized mixture.
And sequentially carrying out rolling composite film forming and thinning on the fiberized mixture to prepare the primary electrode film.
And (3) coating polyvinylidene fluoride on one side surface of the primary electrode film, drying, and carrying out hot pressing treatment at 130 ℃ to obtain the electrode film containing the polyvinylidene fluoride layer.
The thickness of the electrode film after rolling is 150 μm; wherein the polyvinylidene fluoride layer has a thickness of 5 μm.
And (3) carrying out dry-process compounding on the electrode film prepared by the steps and a solid electrolyte film, attaching the solid electrolyte film to a polyvinylidene fluoride layer in the electrode film, and rolling to prepare the composite positive plate. The composition of the solid electrolyte membrane was 5wt% ptfe and 95wt% lithium lanthanum zirconium oxide (LLZO, homemade).
Preparing a negative electrode plate:
and weighing 95%, 2% and 3% of materials by mass of graphite serving as a negative electrode active material, acetylene black serving as a conductive agent and polytetrafluoroethylene serving as a binder in the mixture, and mixing by using an airflow pulverizer to prepare the mixture.
And (3) carrying out fiberizing treatment on the mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain the fiberized mixture.
And sequentially carrying out rolling composite film forming and thinning on the fiberized mixture to prepare the negative electrode plate.
Preparation of a lithium ion battery:
and (3) sequentially stacking and placing a composite positive electrode plate, a diaphragm (PE film, self-made) and a negative electrode plate, injecting liquid and electrolyte (EC: DMC=1:1vol%) after rolling, and forming the lithium salt in the electrolyte into bis (trifluoromethanesulfonyl imide) lithium (LITFSI, the concentration is 1 mol/L), thereby preparing the lithium ion battery.
Example 2
This example 2 is different from example 1 in that a polyvinylidene fluoride (PVDF) layer is provided on one side surface of the primary electrode film by a dry electrostatic spray process.
The spraying process comprises the following steps:
polyvinylidene fluoride (PVDF) was sprayed vertically onto a primary electrode film provided on a receiving device of a spraying apparatus under acceleration of 100kPa of nitrogen gas at a spraying voltage of 23kV, a receiving distance of 10cm, and a spraying time of 3 minutes.
Preparing a composite positive plate:
according to the mass percentages of the positive electrode active material lithium manganate, the conductive agent ketjen black and the binder polytetrafluoroethylene in the mixture, respectively weighing 96%, 2% and 2%, and mixing by an airflow pulverizer to obtain the mixture.
And (3) carrying out fiberizing treatment on the mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain the fiberized mixture.
And sequentially carrying out rolling composite film forming and thinning on the fiberized mixture to prepare the primary electrode film.
And carrying out dry electrostatic spraying on the surface of one side of the primary electrode film to obtain the electrode film containing the polyvinylidene fluoride layer.
The thickness of the electrode film after rolling is 150 μm; wherein the polyvinylidene fluoride layer has a thickness of 5 μm.
And (3) carrying out dry-process compounding on the electrode film prepared by the steps and a solid electrolyte film, attaching the solid electrolyte film to a polyvinylidene fluoride layer in the electrode film, and rolling to prepare the composite positive plate. The composition of the solid electrolyte membrane was 5wt% ptfe and 95wt% lithium lanthanum zirconium oxide (LLZO, homemade).
Preparing a negative electrode plate:
and weighing 95%, 2% and 3% of materials by mass of graphite serving as a negative electrode active material, acetylene black serving as a conductive agent and polytetrafluoroethylene serving as a binder in the mixture, and mixing by using an airflow pulverizer to prepare the mixture.
And (3) carrying out fiberizing treatment on the mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain the fiberized mixture.
And sequentially carrying out rolling composite film forming and thinning on the fiberized mixture to prepare the negative electrode plate.
Preparation of a lithium ion battery:
and (3) sequentially stacking and placing a composite positive electrode plate, a diaphragm (PE film, self-made) and a negative electrode plate, injecting liquid and electrolyte (EC: DMC=1:1vol%) after rolling, and forming the lithium salt in the electrolyte into bis (trifluoromethanesulfonyl imide) lithium (LITFSI, the concentration is 1 mol/L), thereby preparing the lithium ion battery.
Example 3
This example differs from example 1 in the thickness of the polyvinylidene fluoride (PVDF) layer in the electrode film.
Preparing a composite positive plate:
according to the mass percentages of the positive electrode active material lithium manganate, the conductive agent ketjen black and the binder polytetrafluoroethylene in the mixture, respectively weighing 96%, 2% and 2%, and mixing by an airflow pulverizer to obtain the mixture.
And (3) carrying out fiberizing treatment on the mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain the fiberized mixture.
And sequentially carrying out rolling composite film forming and thinning on the fiberized mixture to prepare the primary electrode film.
And (3) coating polyvinylidene fluoride on one side surface of the primary electrode film, drying, and carrying out hot pressing treatment at 130 ℃ to obtain the electrode film containing the polyvinylidene fluoride layer.
The thickness of the electrode film after rolling is 150 μm; wherein the polyvinylidene fluoride layer has a thickness of 3 μm.
And (3) carrying out dry-process compounding on the electrode film prepared by the steps and a solid electrolyte film, attaching the solid electrolyte film to a polyvinylidene fluoride layer in the electrode film, and rolling to prepare the composite positive plate. The composition of the solid electrolyte membrane was 5wt% ptfe and 95wt% lithium lanthanum zirconium oxide (LLZO, homemade).
Preparing a negative electrode plate:
and weighing 95%, 2% and 3% of materials by mass of graphite serving as a negative electrode active material, acetylene black serving as a conductive agent and polytetrafluoroethylene serving as a binder in the mixture, and mixing by using an airflow pulverizer to prepare the mixture.
And (3) carrying out fiberizing treatment on the mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain the fiberized mixture.
And sequentially carrying out rolling composite film forming and thinning on the fiberized mixture to prepare the negative electrode plate.
Preparation of a lithium ion battery:
and (3) sequentially stacking and placing a composite positive electrode plate, a diaphragm (PE film, self-made) and a negative electrode plate, injecting liquid and electrolyte (EC: DMC=1:1vol%) after rolling, and forming the lithium salt in the electrolyte into bis (trifluoromethanesulfonyl imide) lithium (LITFSI, the concentration is 1 mol/L), thereby preparing the lithium ion battery.
Example 4
This example differs from example 1 in the thickness of the polyvinylidene fluoride (PVDF) layer in the electrode film.
Preparing a composite positive plate:
according to the mass percentages of the positive electrode active material lithium manganate, the conductive agent ketjen black and the binder polytetrafluoroethylene in the mixture, respectively weighing 96%, 2% and 2%, and mixing by an airflow pulverizer to obtain the mixture.
And (3) carrying out fiberizing treatment on the mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain the fiberized mixture.
And sequentially carrying out rolling composite film forming and thinning on the fiberized mixture to prepare the primary electrode film.
And (3) coating polyvinylidene fluoride on one side surface of the primary electrode film, drying, and carrying out hot pressing treatment at 130 ℃ to obtain the electrode film containing the polyvinylidene fluoride layer.
The thickness of the electrode film after rolling is 150 μm; wherein the polyvinylidene fluoride layer has a thickness of 12 μm.
And (3) carrying out dry-process compounding on the electrode film prepared by the steps and a solid electrolyte film, attaching the solid electrolyte film to a polyvinylidene fluoride layer in the electrode film, and rolling to prepare the composite positive plate. The composition of the solid electrolyte membrane was 5wt% ptfe and 95wt% lithium lanthanum zirconium oxide (LLZO, homemade).
Preparing a negative electrode plate:
and weighing 95%, 2% and 3% of materials by mass of graphite serving as a negative electrode active material, acetylene black serving as a conductive agent and polytetrafluoroethylene serving as a binder in the mixture, and mixing by using an airflow pulverizer to prepare the mixture.
And (3) carrying out fiberizing treatment on the mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain the fiberized mixture.
And sequentially carrying out rolling composite film forming and thinning on the fiberized mixture to prepare the negative electrode plate.
Preparation of a lithium ion battery:
and (3) sequentially stacking and placing a composite positive electrode plate, a diaphragm (PE film, self-made) and a negative electrode plate, injecting liquid and electrolyte (EC: DMC=1:1vol%) after rolling, and forming the lithium salt in the electrolyte into bis (trifluoromethanesulfonyl imide) lithium (LITFSI, the concentration is 1 mol/L), thereby preparing the lithium ion battery.
Example 5
This example is different from example 2 in that the negative electrode tab takes the form of a composite negative electrode tab.
Preparing a positive electrode plate:
according to the mass percentages of the positive electrode active material lithium manganate, the conductive agent ketjen black and the binder polytetrafluoroethylene in the mixture, respectively weighing 96%, 2% and 2%, and mixing by an airflow pulverizer to obtain the mixture.
And (3) carrying out fiberizing treatment on the mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain the fiberized mixture.
And sequentially carrying out rolling composite film forming and thinning on the fiberized mixture to prepare the positive electrode plate.
Preparing a composite negative electrode plate:
and weighing 95%, 2% and 3% of materials by mass of graphite serving as a negative electrode active material, acetylene black serving as a conductive agent and polytetrafluoroethylene serving as a binder in the mixture, and mixing by using an airflow pulverizer to prepare the mixture.
And (3) carrying out fiberizing treatment on the mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain the fiberized mixture.
Sequentially forming and thinning the electrode film to prepare a primary electrode film;
and carrying out dry electrostatic spraying on the surface of one side of the primary electrode film to obtain the electrode film containing the polyvinylidene fluoride layer.
The thickness of the electrode film after rolling is 150 μm; wherein the polyvinylidene fluoride layer has a thickness of 5 μm.
The dry electrostatic spraying process comprises the following steps:
polyvinylidene fluoride (PVDF) was vertically sprayed onto an electrode film provided on a receiving device of a spraying apparatus under acceleration of 100kPa of nitrogen gas at a spraying voltage of 23kV, a receiving distance of 10cm, and a spraying time of 3 minutes.
And (3) carrying out dry-process compounding on the electrode film prepared by the steps and a solid electrolyte film, attaching the solid electrolyte film to a polyvinylidene fluoride layer in the electrode film, and rolling to prepare the composite negative electrode plate. The composition of the solid electrolyte membrane was 5wt% ptfe and 95wt% lithium lanthanum zirconium oxide (LLZO, homemade).
Preparation of a lithium ion battery:
and (3) sequentially stacking and placing the positive electrode plate, the diaphragm (PE film, self-made) and the composite negative electrode plate, injecting liquid and electrolyte (EC: DMC=1:1vol%) after rolling, and forming the lithium salt in the electrolyte into bis (trifluoromethanesulfonyl imide) lithium (LITFSI, the concentration is 1 mol/L), thereby preparing the lithium ion battery.
Comparative example 1
The comparative example 1 is different from example 1 in that the step of coating polyvinylidene fluoride is not included in the preparation process of the composite positive electrode sheet in the comparative example.
Preparing a composite positive plate:
according to the mass percentages of the positive electrode active material lithium manganate, the conductive agent ketjen black and the binder polytetrafluoroethylene in the mixture, respectively weighing 96%, 2% and 2%, and mixing by an airflow pulverizer to obtain the mixture.
And (3) carrying out fiberizing treatment on the mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain the fiberized mixture.
And sequentially forming and thinning the fiberizing mixture to prepare the electrode film. The thickness of the electrode film after rolling was 150. Mu.m.
And (3) carrying out dry-process compounding on the electrode film prepared by the steps and the solid electrolyte film, and rolling to prepare the composite positive plate. The composition of the solid electrolyte membrane was 5wt% ptfe and 95wt% lithium lanthanum zirconium oxide (LLZO, homemade).
Preparing a negative electrode plate:
and weighing 95%, 2% and 3% of materials by mass of graphite serving as a negative electrode active material, acetylene black serving as a conductive agent and polytetrafluoroethylene serving as a binder in the mixture, and mixing by using an airflow pulverizer to prepare the mixture.
And (3) carrying out fiberizing treatment on the mixture by a high-speed shearing machine at the rotating speed of 25000r/min for 10min to obtain the fiberized mixture.
And sequentially carrying out rolling composite film forming and thinning on the fiberized mixture to prepare the negative electrode plate.
Preparation of a lithium ion battery:
and (3) sequentially stacking and placing a composite positive electrode plate, a diaphragm (PE film, self-made) and a negative electrode plate, injecting liquid and electrolyte (EC: DMC=1:1vol%) after rolling, and forming the lithium salt in the electrolyte into bis (trifluoromethanesulfonyl imide) lithium (LITFSI, the concentration is 1 mol/L), thereby preparing the lithium ion battery.
In the examples and comparative examples of the present application, lithium manganate was derived from Anhui Boshi BM6B; the conductive agent Keqin black is from Shanghai Cuicake chemical EC-600JD; polytetrafluoroethylene is derived from Japanese Dajin D-2C; polyvinylidene fluoride is from alcma HSV1810; graphite from fir family technology EV7; acetylene black from DENKA LI250; lithium bis (trifluoromethanesulfonyl imide) is derived from sigma aldrich.
Test case
(1) Cycle test
Charging at a temperature of 25+/-2 ℃ at 1C or a specified current to a final voltage, cutting off the current by 0.05C, and standing for 30min; secondly, discharging to a discharge final pressure (2.75V) at 1C, recording discharge capacity, and standing for 30min; the first and second steps were cycled and the battery was tested for 500 cycles of cycling performance. The test results are shown in table 1 below.
(2) Peel strength test
Firstly, a composite film formed by an electrode plate and a solid electrolyte film is cut into long strips with the length of 170mm and the width of 20mm respectively by using a flat paper cutter, and then a non-scale steel plate ruler is wiped clean by using dust-free paper, so that dirt and dust are not remained.
Secondly, a double-sided adhesive tape with the width of 25mm is stuck on a steel plate ruler without graduation, the length is 70mm, and the position is centered.
Then the composite film is stuck on a double-sided adhesive tape, the end faces are flush, and a pressing wheel (2 kg) with the diameter of 84mm and the height of 45mm is used for rolling back and forth on the surface of the composite film for 3 times.
And (3) after the free end of the composite film in the experimental sample is turned over by 180 degrees, the composite film is clamped on an upper clamp of a tensile tester, a non-scale steel plate ruler is clamped on a lower clamp, a plurality of composite films with the width of 20mm are prepared under the conditions that the temperature is 22-28 ℃ and the humidity is less than 25%, the stretching speed of the composite films is 200mm/min, the average value of stretching 25-mm mm (total stretching distance is 100 mm) is measured, the composite films are peeled, and the test result of the peeling strength of the composite films is read when electrode plates and solid electrolyte films in the composite films are completely separated. The test results are shown in table 1 below.
According to the experimental data, the composite electrode plate prepared by arranging the PVDF layer on the surface of the primary electrode film has a relatively low melting point, so that a relatively good bonding effect can be achieved in the process of compositing the electrode film and the solid electrolyte film, and the bonding strength of the composite electrode plate formed by the electrode film and the solid electrolyte film is improved.
Meanwhile, as can be seen from comparison of the embodiment 1 and the embodiment 2, the method can realize the complete dry process preparation of the composite electrode pole piece through a spraying process, and compared with the method for setting the PVDF layer through a coating process, the cycle performance and the peeling strength can basically reach the same level.
In addition, when the PVDF layer is too thin or too thick, it is known from comparison of example 1 and example 3 that when the PVDF layer is thin, the bonding strength between the electrode membrane and the solid electrolyte membrane is affected; as can be seen from a comparison of example 1 and example 4, when the PVDF layer is excessively thick, it causes an increase in the internal resistance of the battery, affecting the cycle performance of the battery.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The foregoing examples represent only a few embodiments of the present application, which are described in more detail and are not thereby to be construed as limiting the scope of the claims. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.

Claims (7)

1. The preparation method of the composite electrode slice is characterized by comprising the following steps:
s1, preparing an electrode film:
s1-1, mixing an active material, a conductive agent and a binder to prepare a mixture;
s1-2, carrying out fibrosis treatment on the mixture to obtain a fibrosis mixture;
s1-3, carrying out calendaring treatment on the fiberizing mixture to obtain a primary electrode film;
s1-4, setting polyvinylidene fluoride on one side surface of the primary electrode film to prepare an electrode film containing a polyvinylidene fluoride layer;
the binder comprises polytetrafluoroethylene;
s2, carrying out dry-process compounding on the electrode film prepared in the step S1 and a solid electrolyte film, and attaching the solid electrolyte film to a polyvinylidene fluoride layer in the electrode film; and
s3, obtaining a composite electrode plate;
in the step S1-2, in the process of preparing the fiberizing mixture, a high-speed shearing machine is adopted to carry out fiberizing treatment under the condition that the rotating speed is 20000 r/min-28000 r/min;
setting polyvinylidene fluoride on one side surface of the primary electrode film in the step S1-4 by adopting a dry electrostatic spraying mode to prepare an electrode film containing the polyvinylidene fluoride layer;
vertically spraying the film onto the primary electrode film arranged on a receiving device of spraying equipment under the acceleration of 100kPa nitrogen, wherein the spraying voltage is 23kV, the receiving distance is 10cm, and the spraying time is 3min;
the thickness of the polyvinylidene fluoride layer is 3-5 mu m.
2. The production method according to claim 1, wherein in the step S2, the electrode film and the solid electrolyte film are dry-compounded with an elastic roller.
3. The method according to claim 2, wherein in the step S2, the pressing temperature is 60 ℃ to 160 ℃ in the dry compounding process.
4. The preparation method according to claim 1, wherein in the mixture, the active material, the conductive agent and the binder are 85% -98%, 1% -10% and 1% -10% by mass, respectively.
5. The method according to claim 1, wherein the thickness of the composite electrode sheet is 50 μm to 500 μm.
6. A composite electrode sheet, characterized in that it is produced according to the production method of any one of claims 1 to 5.
7. A lithium ion battery characterized in that the lithium ion battery comprises a composite electrode sheet manufactured by the manufacturing method according to any one of claims 1 to 5.
CN202311321320.2A 2023-10-12 2023-10-12 Composite electrode plate, preparation method thereof and lithium ion battery Active CN117096281B (en)

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Citations (6)

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Publication number Priority date Publication date Assignee Title
JP2001015125A (en) * 1999-06-29 2001-01-19 Kyocera Corp Lithium battery
CN113571672A (en) * 2021-07-26 2021-10-29 中汽创智科技有限公司 Dry electrode, solid lithium ion battery and preparation method thereof
CN113594537A (en) * 2021-08-29 2021-11-02 惠州赣锋锂电科技有限公司 Safety battery and preparation method thereof
CN115995618A (en) * 2021-10-18 2023-04-21 芯量科技股份有限公司 Solid electrolyte film, method for manufacturing the same, and battery including the solid electrolyte film
CN116581250A (en) * 2023-07-12 2023-08-11 苏州清陶新能源科技有限公司 Composite pole piece, preparation method thereof and lithium ion battery
CN116779767A (en) * 2023-08-17 2023-09-19 蔚来电池科技(安徽)有限公司 Electrode plate, preparation method thereof, secondary battery and device

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001015125A (en) * 1999-06-29 2001-01-19 Kyocera Corp Lithium battery
CN113571672A (en) * 2021-07-26 2021-10-29 中汽创智科技有限公司 Dry electrode, solid lithium ion battery and preparation method thereof
CN113594537A (en) * 2021-08-29 2021-11-02 惠州赣锋锂电科技有限公司 Safety battery and preparation method thereof
CN115995618A (en) * 2021-10-18 2023-04-21 芯量科技股份有限公司 Solid electrolyte film, method for manufacturing the same, and battery including the solid electrolyte film
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