CN114551801B - Silicon-carbon composite pole piece and preparation method and application thereof - Google Patents

Silicon-carbon composite pole piece and preparation method and application thereof Download PDF

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CN114551801B
CN114551801B CN202210137247.2A CN202210137247A CN114551801B CN 114551801 B CN114551801 B CN 114551801B CN 202210137247 A CN202210137247 A CN 202210137247A CN 114551801 B CN114551801 B CN 114551801B
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silicon
carbon
conductive layer
stirring
pole piece
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CN114551801A (en
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邓松辉
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Eve Energy Co Ltd
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Eve Energy 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • 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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • 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
    • 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
    • H01M4/386—Silicon or alloys based on silicon
    • 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
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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

The invention provides a silicon-carbon composite pole piece and a preparation method and application thereof. The invention provides enough expansion buffer space for the silicon-based material, improves the manufacturability of the material, can effectively avoid the problem of failure of a conductive network caused by expansion of silicon carbon in the charge and discharge process, and improves the cycle performance of the pole piece.

Description

Silicon-carbon composite pole piece and preparation method and application thereof
Technical Field
The invention belongs to the technical field of batteries, relates to a silicon-carbon composite pole piece, and particularly relates to a silicon-carbon composite pole piece, and a preparation method and application thereof.
Background
The single-wall carbon nano tube is composed of carbon atoms, the geometric structure can be regarded as being formed by curling single-layer graphene, and the structure determines the property, so that the single-wall carbon nano tube has excellent electronic, mechanical and other properties. Compared with the multi-wall carbon nano tube, the lithium battery slurry has higher length-diameter ratio, and the single-wall carbon nano tube is added in the lithium battery slurry formula, so that the system conductivity can be effectively improved. At present, the energy density of the battery is required to be higher and higher, the capacity of the positive electrode reaches the bottleneck, and the lifting space is small, so that the application of the silicon-based material as an estimation material is wider and wider, but the charging cycle easily causes the failure of the conductive network due to the expansion of the silicon-based material.
CN107331888A discloses a lithium ion battery containing a silicon carbon material negative plate, which comprises a positive plate, a negative plate, a diaphragm, electrolyte and a shell, wherein the positive plate comprises an aluminum foil and positive active substances distributed on the aluminum foil, the negative plate is a silicon carbon material negative plate, the silicon carbon material negative plate contains a conductive carbon coating, the conductive carbon coating is positioned between a current collector layer and an active substance layer, the diaphragm is one of a polyolefin diaphragm, a ceramic coating diaphragm and a non-woven fabric diaphragm, the electrolyte is an organic solution of lithium hexafluorophosphate, and the shell is one of a steel shell, an aluminum shell, a plastic shell or an aluminum plastic film.
CN105406044a discloses an anti-expansion silicon-carbon negative plate, which consists of a metal foil coated with a slurry; the slurry comprises a silicon carbon powder body with built-in graphene, a binder, a solvent and carbon nanotubes; the slurry contains 90-95% of silicon carbon powder of graphene, 3-4.5% of binder and 0.5-2.5% of carbon nano tube by mass percent.
CN109494374a discloses a silicon-carbon negative electrode plate of a lithium ion battery and a preparation method thereof, wherein the silicon-carbon negative electrode plate is in a sandwich layered structure, and is sequentially provided with a netty micro-through hole copper foil current collector, a conductive carbon coating and a negative electrode active material layer from inside to outside; the preparation method comprises the following steps: 1) Preparing a conductive carbon coating; 2) A copper foil current collector with net-shaped micro-through holes is selected, and a conductive carbon coating is coated on the surface of the copper foil current collector; 3) Preparing negative electrode slurry; 4) And (3) coating the negative electrode slurry on a netlike micro-through hole copper foil current collector with a conductive carbon coating, baking, rolling, slitting and die cutting to obtain a negative electrode plate.
The existing pole piece of the silicon-based material is expanded, and the charging cycle easily causes the failure of the conductive network, so how to avoid the failure of the conductive network caused by expansion becomes the important focus direction of the prior art.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to provide a silicon-carbon composite pole piece, a preparation method and application thereof, which provide enough expansion buffer space for silicon-based materials, improve the manufacturability of the materials, and simultaneously facilitate obtaining pole pieces with higher conductivity, and the silicon-carbon active substances are arranged in the conductive layer, so that the problem of failure of a conductive network caused by expansion of silicon-carbon in the charge and discharge process can be effectively avoided, and the cycle performance of the pole pieces is improved.
To achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a silicon-carbon composite pole piece, where the silicon-carbon composite pole piece includes a substrate, at least one side surface of the substrate is sequentially laminated with a first conductive layer and a second conductive layer, a silicon-carbon active material is dispersed in the first conductive layer, and the first conductive layer and the second conductive layer independently include single-walled carbon nanotubes.
According to the silicon-carbon composite pole piece, the conductive layers are sequentially laminated, so that enough expansion buffer space is provided for the silicon-based material, the manufacturability of the material is improved, the pole piece with higher conductivity is facilitated to be obtained, and the silicon-carbon active substance is arranged in the conductive layer, so that the problem of failure of a conductive network caused by expansion in the charging and discharging process of silicon-carbon can be effectively avoided, and the cycle performance of the pole piece is improved.
As a preferred embodiment of the present invention, the substrate includes copper foil.
The thickness of the copper foil is preferably 0.03 to 0.2mm, and may be, for example, 0.03mm, 0.05mm, 0.07mm, 0.08mm, 0.1mm, 0.12mm, 0.13mm, 0.15mm, 0.18mm or 0.2mm, but is not limited to the values recited, and other values not recited in the numerical range are equally applicable.
In a preferred embodiment of the present invention, the diameter of the single-walled carbon nanotube is 0.5 to 4.5nm, and may be, for example, 0.5nm, 0.8nm, 1nm, 1.5nm, 1.8nm, 2nm, 2.3nm, 2.5nm, 3nm, 3.2nm, 3.5nm, 4nm, 4.3nm or 4.5nm, but not limited to the values recited, and other values not recited in the numerical range are equally applicable.
Preferably, the mass percentage of the single-walled carbon nanotube is 0.2 to 0.8% based on 100% of the mass of the first conductive layer or the second conductive layer, and may be, for example, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7% or 0.8%, but is not limited to the recited values, and other non-recited values within the range are equally applicable.
Preferably, the thickness of the first conductive layer and the second conductive layer is independently 450 to 1800nm, for example, 450nm, 480nm, 500nm, 550nm, 600nm, 650nm, 700nm, 800nm, 1000nm, 1200nm, 1300nm, 1500nm, 1550nm, 1600nm, 1650nm, 1700nm, 1750nm or 1800nm, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, the silicon carbon active material comprises silicon carbon.
Preferably, the silicon-carbon active material is 100% by mass, and the silicon-carbon content is 63.7 to 64.4% by mass, and may be 63.7%, 63.8%, 63.9%, 64%, 64.1%, 64.2%, 64.3% or 64.4% by mass, for example, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.
In a second aspect, the invention provides a preparation method of the silicon-carbon composite pole piece in the first aspect, which comprises the following steps:
preparing a first glue solution, dispersing single-wall carbon nanotubes in the first glue solution to obtain conductive slurry, preparing a second glue solution, and dispersing silicon carbon in the second glue solution to obtain a silicon carbon active substance;
(II) providing a substrate, coating the conductive paste in the step (I) on at least one side surface of the substrate to form a first conductive layer, and then embedding the silicon-carbon active material in the step (I) into the first conductive layer to obtain a prefabricated pole piece;
and (III) coating the conductive paste in the step (I) on at least one side surface of the prefabricated pole piece in the step (II) to form a second conductive layer, so as to obtain the silicon-carbon composite pole piece.
In the preparation method provided by the invention, the surface of the first conductive layer of the prefabricated pole piece is coated with the conductive paste, so that the first conductive layer and the second conductive layer which are sequentially laminated are formed.
As a preferred embodiment of the present invention, in the step (I), the preparing the first glue solution includes: and mixing polyvinylidene fluoride, polyvinylpyrrolidone and N-methyl pyrrolidone, and stirring for one time to obtain the first glue solution.
Preferably, the mass percentage of the single-walled carbon nanotubes in the conductive paste is 0.2-0.8%, for example, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7% or 0.8%, but is not limited to the recited values, and other non-recited values within the range are equally applicable.
Preferably, the mass percentage of polyvinylidene fluoride in the conductive paste is 8-10%, for example, 8%, 8.2%, 8.3%, 8.5%, 8.6%, 8.8%, 8.9%, 9%, 9.3%, 9.5%, 9.6%, 9.7%, 9.8%, 9.9% or 10%, but not limited to the recited values, and other non-recited values within the range are equally applicable.
Preferably, the mass percentage of polyvinylpyrrolidone in the conductive paste is 0.6-1%, for example, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95% or 1%, but not limited to the recited values, and other non-recited values in the range are equally applicable.
Preferably, the mass percentage of N-methylpyrrolidone in the conductive paste is 88.2 to 91.2%, for example 88.2%, 88.3%, 88.5%, 88.6%, 88.8%, 88.9%, 90%, 90.3%, 90.5%, 90.6%, 90.7%, 90.8%, 91% or 91.2%, but not limited to the recited values, and other non-recited values in the range of values are equally applicable.
As a preferred embodiment of the present invention, in the step (I), the preparing the second glue solution includes: and mixing polyacrylic acid with deionized water, and then stirring for the second time to obtain the second glue solution.
Preferably, the silicon-carbon active material has a mass percentage of 63.7-64.4%, for example, 63.7%, 63.8%, 63.9%, 64%, 64.1%, 64.2%, 64.3% or 64.4%, but is not limited to the recited values, and other non-recited values within the range are equally applicable.
The mass percentage of polyacrylic acid in the silicon carbon active material is preferably 0.7 to 1.3%, for example, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, 1.15%, 1.2%, 1.25% or 1.3%, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, the mass percentage of deionized water in the silicon carbon active material is 34.3-35.6%, for example 34.3%, 34.4%, 34.5%, 34.7%, 34.8%, 35%, 35.2%, 35.3%, 35.5% or 35.6%, but not limited to the recited values, and other non-recited values within the range are equally applicable.
In the step (I), the single-walled carbon nanotubes are dispersed in the first glue solution and then subjected to vacuum stirring.
The revolution speed of the primary stirring and the primary vacuum stirring is preferably 20 to 25rpm, and may be, for example, 20rpm, 21rpm, 22rpm, 23rpm, 24rpm or 25rpm, but is not limited to the recited values, and other non-recited values within the range are equally applicable.
The dispersion speed of the primary stirring and the primary vacuum stirring is preferably 2500 to 3000rpm, and may be 2500rpm, 2600rpm, 2700rpm, 2800rpm, 2900rpm or 3000rpm, for example, but the present invention is not limited to the above-mentioned values, and other values not mentioned in the above-mentioned range are applicable.
Preferably, the time of the one stirring is 285 to 325min, for example, 285min, 290min, 295min, 300min, 310min, 315min, 320min or 325min, but not limited to the recited values, and other non-recited values within the range are equally applicable.
Preferably, the time of the primary vacuum stirring is 285 to 325min, for example, 285min, 290min, 295min, 300min, 310min, 315min, 320min or 325min, but not limited to the recited values, and other non-recited values within the range are equally applicable.
Preferably, in the step (I), the silicon carbon is dispersed in the second glue solution to be subjected to secondary vacuum stirring.
The revolution speed of the secondary stirring and the secondary vacuum stirring is preferably 20 to 25rpm, and may be, for example, 20rpm, 21rpm, 22rpm, 23rpm, 24rpm or 25rpm, but is not limited to the recited values, and other non-recited values within the range are equally applicable.
The dispersion speed of the secondary stirring and the secondary vacuum stirring is preferably 2500 to 3000rpm, and may be 2500rpm, 2600rpm, 2700rpm, 2800rpm, 2900rpm or 3000rpm, for example, but the above-mentioned values are not limited thereto, and other values not shown in the above-mentioned value range are equally applicable.
Preferably, the time of the secondary stirring is 285-325 min, for example 285min, 290min, 295min, 300min, 310min, 315min, 320min or 325min, but not limited to the recited values, and other non-recited values within the range are equally applicable.
Preferably, the time of the secondary vacuum stirring is 455-515 min, for example, 455min, 460min, 475min, 480min, 485min, 490min, 495min, 500min, 510min or 515min, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.
In the step (ii), the conductive paste is coated on the surface of the substrate and then dried once.
Preferably, the embedding includes: and (3) distributing the silicon-carbon active substances on the surface of the first conductive layer at intervals by adopting an anilox roller, then carrying out secondary drying, and then pressing to enable the silicon-carbon active substances to be completely embedded into the first conductive layer, so as to obtain the prefabricated pole piece.
Preferably, said pressing comprises rolling.
Preferably, in the step (iii), the conductive paste is coated on the surface of the prefabricated pole piece and then dried three times.
As a preferable technical scheme of the invention, the preparation method specifically comprises the following steps:
(1) Mixing polyvinylidene fluoride, polyvinylpyrrolidone and N-methyl pyrrolidone, stirring for 285-325 min for one time to obtain a first glue solution, dispersing single-walled carbon nanotubes in the first glue solution, and stirring for one time for 285-325 min in vacuum to obtain conductive slurry, wherein the conductive slurry comprises the following components in percentage by mass: 0.2 to 0.8 percent of single-wall carbon nano tube, 8 to 10 percent of polyvinylidene fluoride, 0.6 to 1 percent of polyvinylpyrrolidone and 88.2 to 91.2 percent of N-methyl pyrrolidone, wherein revolution speeds of primary stirring and primary vacuum stirring are independently 20 to 25rpm, and dispersion speeds are independently 2500 to 3000rpm;
(2) Mixing polyacrylic acid with deionized water, performing secondary stirring for 285-325 min to obtain a second glue solution, dispersing silicon carbon in the second glue solution, and performing secondary vacuum stirring for 455-515 min to obtain silicon carbon active substances, wherein the silicon carbon active substances comprise the following components in percentage by mass: 63.7 to 64.4 percent of silicon carbon, 0.7 to 1.3 percent of polyacrylic acid and 34.3 to 35.6 percent of deionized water, wherein revolution speeds of secondary stirring and secondary vacuum stirring are independently 20 to 25rpm, and dispersion speeds are independently 2500 to 3000rpm;
(3) Providing a copper foil, respectively coating the conductive paste in the step (1) on at least one side surface of the copper foil, performing primary drying to obtain a first conductive layer, adopting an anilox roller to distribute the silicon-carbon active substances in the step (2) on the surface of the first conductive layer at intervals, performing secondary drying, and then performing rolling to enable the silicon-carbon active substances to be completely embedded into the first conductive layer to obtain a prefabricated pole piece;
(4) And (3) respectively coating the conductive paste in the step (1) on the surfaces of the two sides of the prefabricated pole piece in the step (3), and then drying for three times to form a second conductive layer to obtain the silicon-carbon composite pole piece.
In a third aspect, the invention provides an application of the silicon-carbon composite pole piece in the first aspect, wherein the silicon-carbon composite pole piece is applied to preparation of lithium ion batteries.
Compared with the prior art, the invention has the beneficial effects that:
according to the silicon-carbon composite pole piece, the conductive layers are sequentially laminated in the preparation method and the application of the silicon-carbon composite pole piece, enough expansion buffer space is provided for the silicon-based material, the manufacturability of the material is improved, meanwhile, the pole piece with higher conductivity is facilitated to be obtained, and the silicon-carbon active substance is arranged in the conductive layer, so that the problem of failure of a conductive network caused by expansion of silicon-carbon in the charge and discharge process can be effectively avoided, and the cycle performance of the pole piece is improved.
Drawings
Fig. 1 is a schematic diagram of a preparation step of a silicon-carbon composite pole piece provided in embodiment 1 of the present invention.
Wherein, 1-substrate; 2-a first conductive layer; 3-a second conductive layer; 4-silicon carbon active material.
Detailed Description
The technical scheme of the invention is further described below by the specific embodiments with reference to the accompanying drawings.
Example 1
The embodiment provides a silicon-carbon composite pole piece, which comprises a substrate 1, wherein a first conductive layer 2 and a second conductive layer 3 are sequentially laminated on the surfaces of two sides of the substrate 1, a silicon-carbon active substance 4 is dispersed in the first conductive layer 2, and the first conductive layer 2 and the second conductive layer 3 independently comprise single-walled carbon nanotubes. The substrate 1 was a copper foil having a thickness of 0.15 mm.
As shown in fig. 1, the preparation method of the silicon-carbon composite pole piece is as follows:
(1) Mixing polyvinylidene fluoride, polyvinylpyrrolidone and N-methyl pyrrolidone, stirring for 300min for one time to obtain a first glue solution, dispersing single-wall carbon nanotubes with the diameter of 3nm in the first glue solution, and stirring for 300min for one time in vacuum to obtain conductive slurry, wherein the mass percentages of the components in the conductive slurry are as follows: 0.5% of single-wall carbon nano tube, 8.8% of polyvinylidene fluoride, 0.8% of polyvinylpyrrolidone and 89.9% of N-methyl pyrrolidone, wherein revolution speeds of one-time stirring and one-time vacuum stirring are 25rpm, and dispersion speeds are 3000rpm;
(2) Mixing polyacrylic acid with deionized water, performing secondary stirring for 300min to obtain a second glue solution, dispersing silicon carbon in the second glue solution, and performing secondary vacuum stirring for 480min to obtain a silicon carbon active substance 4, wherein the silicon carbon active substance 4 comprises the following components in percentage by mass: 64% of silicon carbon, 1.1% of polyacrylic acid and 34.9% of deionized water, wherein revolution speeds of secondary stirring and secondary vacuum stirring are 25rpm, and dispersion speeds are 3000rpm;
(3) Providing a copper foil, respectively coating the conductive paste in the step (1) on the surfaces of two sides of the copper foil, performing primary drying to obtain a first conductive layer 2, adopting an anilox roller to distribute silicon-carbon active substances 4 in the step (2) on the surface of the first conductive layer 2 at intervals, performing secondary drying, and then performing rolling to enable the silicon-carbon active substances 4 to be completely embedded into the first conductive layer 2, so as to obtain a prefabricated pole piece;
(4) And (3) respectively coating the conductive paste in the step (1) on the surfaces of the two sides of the prefabricated pole piece in the step (3), and then drying for three times to form a second conductive layer 3, thereby obtaining the silicon-carbon composite pole piece.
Example 2
The embodiment provides a silicon-carbon composite pole piece, which comprises a substrate 1, wherein a first conductive layer 2 and a second conductive layer 3 are sequentially laminated on the surfaces of two sides of the substrate 1, a silicon-carbon active substance 4 is dispersed in the first conductive layer 2, and the first conductive layer 2 and the second conductive layer 3 independently comprise single-walled carbon nanotubes. The base 1 was a copper foil having a thickness of 0.08 mm.
The preparation method of the silicon-carbon composite pole piece is as follows:
(1) Mixing polyvinylidene fluoride, polyvinylpyrrolidone and N-methyl pyrrolidone, stirring for 285min for one time to obtain a first glue solution, dispersing single-wall carbon nanotubes with the diameter of 0.8nm in the first glue solution, and stirring for one time for 285min in vacuum to obtain conductive slurry, wherein the conductive slurry comprises the following components in percentage by mass: 0.3% of single-wall carbon nano tube, 8.5% of polyvinylidene fluoride, 1% of polyvinylpyrrolidone and 90.2% of N-methyl pyrrolidone, wherein revolution speeds of primary stirring and primary vacuum stirring are 23rpm, and dispersing speeds are 2800rpm;
(2) Mixing polyacrylic acid with deionized water, performing secondary stirring for 310min to obtain a second glue solution, dispersing silicon carbon in the second glue solution, and performing secondary vacuum stirring for 460min to obtain a silicon carbon active substance 4, wherein the silicon carbon active substance 4 comprises the following components in percentage by mass: 63.8% of silicon carbon, 0.8% of polyacrylic acid and 35.4% of deionized water, wherein revolution speeds of secondary stirring and secondary vacuum stirring are 25rpm, and dispersing speeds are 2800rpm;
(3) Providing a copper foil, respectively coating the conductive paste in the step (1) on the surfaces of two sides of the copper foil, performing primary drying to obtain a first conductive layer 2, adopting an anilox roller to distribute silicon-carbon active substances 4 in the step (2) on the surface of the first conductive layer 2 at intervals, performing secondary drying, and then performing rolling to enable the silicon-carbon active substances 4 to be completely embedded into the first conductive layer 2, so as to obtain a prefabricated pole piece;
(4) And (3) respectively coating the conductive paste in the step (1) on the surfaces of the two sides of the prefabricated pole piece in the step (3), and then drying for three times to form a second conductive layer 3, thereby obtaining the silicon-carbon composite pole piece.
Example 3
The embodiment provides a silicon-carbon composite pole piece, which comprises a substrate 1, wherein a first conductive layer 2 and a second conductive layer 3 are sequentially laminated on the surfaces of two sides of the substrate 1, a silicon-carbon active substance 4 is dispersed in the first conductive layer 2, and the first conductive layer 2 and the second conductive layer 3 independently comprise single-walled carbon nanotubes. The base 1 was a copper foil having a thickness of 0.1 mm.
The preparation method of the silicon-carbon composite pole piece is as follows:
(1) Mixing polyvinylidene fluoride, polyvinylpyrrolidone and N-methyl pyrrolidone, stirring for 315min to obtain a first glue solution, dispersing single-wall carbon nanotubes with the diameter of 4nm in the first glue solution, and stirring for 315min in vacuum to obtain conductive slurry, wherein the mass percentages of the components in the conductive slurry are as follows: 0.7% of single-wall carbon nano tube, 9% of polyvinylidene fluoride, 0.6% of polyvinylpyrrolidone and 89.7% of N-methyl pyrrolidone, wherein revolution speeds of primary stirring and primary vacuum stirring are 23rpm, and dispersion speeds are 2500rpm;
(2) Mixing polyacrylic acid with deionized water, performing secondary stirring for 315min to obtain a second glue solution, dispersing silicon carbon in the second glue solution, and performing secondary vacuum stirring for 480min to obtain a silicon carbon active substance 4, wherein the silicon carbon active substance 4 comprises the following components in percentage by mass: 63.7% of silicon carbon, 0.7% of polyacrylic acid and 35.6% of deionized water, wherein revolution speeds of secondary stirring and secondary vacuum stirring are 21rpm, and dispersion speeds are 2900rpm;
(3) Providing a copper foil, respectively coating the conductive paste in the step (1) on the surfaces of two sides of the copper foil, performing primary drying to obtain a first conductive layer 2, adopting an anilox roller to distribute silicon-carbon active substances 4 in the step (2) on the surface of the first conductive layer 2 at intervals, performing secondary drying, and then performing rolling to enable the silicon-carbon active substances 4 to be completely embedded into the first conductive layer 2, so as to obtain a prefabricated pole piece;
(4) And (3) respectively coating the conductive paste in the step (1) on the surfaces of the two sides of the prefabricated pole piece in the step (3), and then drying for three times to form a second conductive layer 3, thereby obtaining the silicon-carbon composite pole piece.
Example 4
The embodiment provides a silicon-carbon composite pole piece, which comprises a substrate 1, wherein a first conductive layer 2 and a second conductive layer 3 are sequentially laminated on the surfaces of two sides of the substrate 1, a silicon-carbon active substance 4 is dispersed in the first conductive layer 2, and the first conductive layer 2 and the second conductive layer 3 independently comprise single-walled carbon nanotubes. The substrate 1 was a copper foil having a thickness of 0.18 mm.
The preparation method of the silicon-carbon composite pole piece is as follows:
(1) Mixing polyvinylidene fluoride, polyvinylpyrrolidone and N-methyl pyrrolidone, stirring for 320min to obtain a first glue solution, dispersing single-wall carbon nanotubes with the diameter of 2nm in the first glue solution, and stirring for 320min in vacuum to obtain conductive slurry, wherein the conductive slurry comprises the following components in percentage by mass: 0.2% of single-wall carbon nano tube, 10% of polyvinylidene fluoride, 0.9% of polyvinylpyrrolidone and 88.9% of N-methyl pyrrolidone, wherein revolution speeds of primary stirring and primary vacuum stirring are 22rpm, and dispersion speeds are 2600rpm;
(2) Mixing polyacrylic acid with deionized water, performing secondary stirring for 290min to obtain a second glue solution, dispersing silicon carbon in the second glue solution, and performing secondary vacuum stirring for 500min to obtain a silicon carbon active substance 4, wherein the silicon carbon active substance 4 comprises the following components in percentage by mass: 64.2% of silicon carbon, 0.8% of polyacrylic acid and 35% of deionized water, wherein revolution speeds of secondary stirring and secondary vacuum stirring are 25rpm, and dispersion speeds are 3000rpm;
(3) Providing a copper foil, respectively coating the conductive paste in the step (1) on the surfaces of two sides of the copper foil, performing primary drying to obtain a first conductive layer 2, adopting an anilox roller to distribute silicon-carbon active substances 4 in the step (2) on the surface of the first conductive layer 2 at intervals, performing secondary drying, and then performing rolling to enable the silicon-carbon active substances 4 to be completely embedded into the first conductive layer 2, so as to obtain a prefabricated pole piece;
(4) And (3) respectively coating the conductive paste in the step (1) on the surfaces of the two sides of the prefabricated pole piece in the step (3), and then drying for three times to form a second conductive layer 3, thereby obtaining the silicon-carbon composite pole piece.
Example 5
The embodiment provides a silicon-carbon composite pole piece, which comprises a substrate 1, wherein a first conductive layer 2 and a second conductive layer 3 are sequentially laminated on the surfaces of two sides of the substrate 1, a silicon-carbon active substance 4 is dispersed in the first conductive layer 2, and the first conductive layer 2 and the second conductive layer 3 independently comprise single-walled carbon nanotubes. The base 1 was a copper foil having a thickness of 0.2mm.
The preparation method of the silicon-carbon composite pole piece is as follows:
(1) Mixing polyvinylidene fluoride, polyvinylpyrrolidone and N-methyl pyrrolidone, stirring for 325min to obtain a first glue solution, dispersing single-wall carbon nanotubes with the diameter of 4.5nm in the first glue solution, and stirring for 325min in vacuum to obtain conductive slurry, wherein the conductive slurry comprises the following components in percentage by mass: 0.8% of single-wall carbon nano tube, 10% of polyvinylidene fluoride, 0.85% of polyvinylpyrrolidone and 88.35% of N-methyl pyrrolidone, wherein revolution speeds of primary stirring and primary vacuum stirring are 24rpm, and dispersion speeds are 3000rpm;
(2) Mixing polyacrylic acid with deionized water, performing secondary stirring for 325min to obtain a second glue solution, dispersing silicon carbon in the second glue solution, and performing secondary vacuum stirring for 515min to obtain a silicon carbon active substance 4, wherein the silicon carbon active substance 4 comprises the following components in percentage by mass: 64.4% of silicon carbon, 1.3% of polyacrylic acid and 34.3% of deionized water, wherein revolution speeds of secondary stirring and secondary vacuum stirring are 24rpm, and dispersion speeds are 3000rpm;
(3) Providing a copper foil, respectively coating the conductive paste in the step (1) on the surfaces of two sides of the copper foil, performing primary drying to obtain a first conductive layer 2, adopting an anilox roller to distribute silicon-carbon active substances 4 in the step (2) on the surface of the first conductive layer 2 at intervals, performing secondary drying, and then performing rolling to enable the silicon-carbon active substances 4 to be completely embedded into the first conductive layer 2, so as to obtain a prefabricated pole piece;
(4) And (3) respectively coating the conductive paste in the step (1) on the surfaces of the two sides of the prefabricated pole piece in the step (3), and then drying for three times to form a second conductive layer 3, thereby obtaining the silicon-carbon composite pole piece.
Example 6
The embodiment provides a silicon-carbon composite pole piece, which comprises a substrate 1, wherein a first conductive layer 2 and a second conductive layer 3 are sequentially laminated on the surfaces of two sides of the substrate 1, a silicon-carbon active substance 4 is dispersed in the first conductive layer 2, and the first conductive layer 2 and the second conductive layer 3 independently comprise single-walled carbon nanotubes. The substrate 1 was a copper foil having a thickness of 0.15 mm.
The preparation method of the silicon-carbon composite pole piece is different from that of the embodiment 1 in that: in the step (1), the mass percentage of the single-walled carbon nanotubes in the conductive paste is 0.1%, and the rest of the process parameters and the operation steps are identical to those of the embodiment 1.
Example 7
The embodiment provides a silicon-carbon composite pole piece, which comprises a substrate 1, wherein a first conductive layer 2 and a second conductive layer 3 are sequentially laminated on the surfaces of two sides of the substrate 1, a silicon-carbon active substance 4 is dispersed in the first conductive layer 2, and the first conductive layer 2 and the second conductive layer 3 independently comprise single-walled carbon nanotubes. The substrate 1 was a copper foil having a thickness of 0.15 mm.
The preparation method of the silicon-carbon composite pole piece is different from that of the embodiment 1 in that: in the step (1), the mass percentage of the single-walled carbon nanotubes in the conductive paste is 1%, and the rest of the process parameters and the operation steps are exactly the same as those of the embodiment 1.
Example 8
The embodiment provides a silicon-carbon composite pole piece, which comprises a substrate 1, wherein a first conductive layer 2 and a second conductive layer 3 are sequentially laminated on the surfaces of two sides of the substrate 1, a silicon-carbon active substance 4 is dispersed in the first conductive layer 2, and the first conductive layer 2 and the second conductive layer 3 independently comprise single-walled carbon nanotubes. The substrate 1 was a copper foil having a thickness of 0.15 mm.
The preparation method of the silicon-carbon composite pole piece is different from that of the embodiment 1 in that: in the step (2), the mass percentage of silicon carbon in the silicon carbon active material 4 is 63%, and the rest of the process parameters and operation steps are exactly the same as those of the example 1.
Example 9
The embodiment provides a silicon-carbon composite pole piece, which comprises a substrate 1, wherein a first conductive layer 2 and a second conductive layer 3 are sequentially laminated on the surfaces of two sides of the substrate 1, a silicon-carbon active substance 4 is dispersed in the first conductive layer 2, and the first conductive layer 2 and the second conductive layer 3 independently comprise single-walled carbon nanotubes. The substrate 1 was a copper foil having a thickness of 0.15 mm.
The preparation method of the silicon-carbon composite pole piece is different from that of the embodiment 1 in that: in the step (2), the mass percentage of silicon carbon in the silicon carbon active material 4 is 65%, and the rest of the process parameters and operation steps are exactly the same as those of the example 1.
Example 10
The present embodiment provides a silicon-carbon composite pole piece, which is different from embodiment 1 in that: in the process of preparing the conductive paste of step (1), SBR binder was used instead of polyvinylidene fluoride, and the remaining process parameters and operation steps were exactly the same as those of example 1.
Comparative example 1
This comparative example provides a silicon carbon composite pole piece, which differs from example 1 in that: the surface of the substrate 1 is not provided with the second conductive layer 3, and the rest of the process parameters and operation steps are exactly the same as in example 1.
Comparative example 2
This comparative example provides a silicon carbon composite pole piece, which differs from example 1 in that: the silicon carbon active material 4 is not disposed in the first conductive layer 2, and the remaining process parameters and operation steps are exactly the same as those of example 1.
Comparative example 3
This comparative example provides a silicon carbon composite pole piece, which differs from example 1 in that: the surface of the substrate 1 is not provided with the first conductive layer 2, and the rest of the process parameters and operation steps are exactly the same as in example 1.
Comparative example 4
This comparative example provides a silicon carbon composite pole piece, which differs from example 1 in that: in the preparation process of the conductive paste in the step (1), graphite is adopted to replace single-walled carbon nanotubes, and other process parameters and operation steps are exactly the same as those in the embodiment 1.
The silicon-carbon negative electrode sheets in examples 1 to 13 and the silicon-carbon composite electrode sheets obtained in comparative examples 1 to 4 were wound with a positive electrode sheet and a separator, respectively, and were molded, and were then placed in an aluminum plastic case, and were subjected to treatment to obtain lithium ion batteries, which were each subjected to performance test, charging and discharging at 0.2, and the first efficiencies were calculated, and the results were shown in table 1.
And (3) testing the cycle performance: the initial thickness of the fully charged battery was recorded at ambient conditions of 25.+ -. 5 ℃ at room temperature, and the cycle capacity retention after 400 weeks of charge and discharge cycles at 1C/1C was as shown in Table 1.
Expansion ratio test: and disassembling the lithium ion battery in a full-charge state in 400-week circulation, measuring the thickness of the pole piece, and comparing the measured thickness with the initial thickness, wherein the calculation formula for calculating the expansion rate of the pole piece is as follows: (pole piece thickness after 400 weeks of cycling-initial pole piece thickness)/initial pole piece thickness 100%) and the results are shown in table 1.
TABLE 1
Numbering device First time efficiency Initial thickness of Expansion ratio Cycle number of weeks Capacity retention rate
Example 1 88.6％ 155μm 2.1％ 400 weeks 93％
Example 2 86.3％ 85μm 2.5％ 400 weeks 91.6％
Example 3 87.6％ 105μm 2.2％ 400 weeks 92.8％
Example 4 88.3％ 185μm 2.1％ 400 weeks 92.8％
Example 5 88.1％ 205μm 2.2％ 400 weeks 92.7％
Example 6 88.6％ 155μm 2.8％ 400 weeks 90.8％
Example 7 88.6％ 155μm 2.4％ 400 weeks 90.6％
Example 8 88.9％ 155μm 2.0％ 400 weeks 92.2％
Example 9 88.6％ 155μm 2.4％ 400 weeks 91.8％
Example 10 84.5％ 155μm 4.7％ 400 weeks 88.9％
Comparative example 1 85.9％ 153μm 3.2％ 400 weeks 89.9％
Comparative example 2 85.7％ 154μm 3.1％ 400 weeks 90.1％
Comparative example 3 84.2％ 152μm 4.6％ 400 weeks 86.4％
Comparative example 4 88.5％ 155μm 5.1％ 400 weeks 92.1％
The silicon-carbon composite pole pieces in the embodiments 1 to 5 have the characteristics of low expansion rate and high capacity retention rate, and are mainly characterized in that the first conductive layer 2 and the second conductive layer 3 which are sequentially laminated provide enough expansion buffer space for silicon-based materials, and the silicon-carbon active substances 4 in the first conductive layer 2 effectively avoid the problem of failure of a conductive network in the charging and discharging process of silicon carbon.
As is apparent from examples 1, 6 and 7, the capacity retention rate of the batteries prepared in examples 6 and 7 is reduced as compared with example 1, because when the content of the single-walled carbon nanotubes in the conductive paste is too low, a good conductive network cannot be formed, the mechanical properties and conductive properties of the electrode sheet are reduced, and further the expansion of the silicon-based material is easily caused, resulting in a reduction in the cycle performance of the battery; when the content of the single-walled carbon nanotubes in the conductive paste is too high, agglomerates are easy to appear in the mixing process of the conductive paste, so that the conductive paste is unevenly dispersed, and the performance of the pole piece is further reduced.
The capacity retention ratio of the batteries prepared in examples 1, 8 and 9 was reduced as compared with example 1, mainly because the NP ratio of the battery was reduced and the cycle performance was reduced when the silicon-carbon content was reduced; when the silicon-carbon content is too high, volume expansion occurs in the charge-discharge process, and the conductive network fails, so that the cycle performance of the battery is reduced.
As can be seen from examples 1 and 10, the first efficiency and the capacity retention rate of the battery prepared in example 10 are both reduced, the expansion rate of the electrode sheet is significantly increased, and the cycle efficiency is significantly reduced, mainly because the dispersibility of the single-walled carbon nanotubes in the polyvinylidene fluoride glue solution system is higher than that of the SBR glue solution system, when SBR is used to replace polyvinylidene fluoride, the dispersibility of the single-walled carbon nanotubes in the solution is reduced, the single-walled carbon nanotubes are easy to agglomerate in the conductive paste, the stability is poor, and further the battery performance is reduced, while the single-walled carbon nanotubes in example 1 can be uniformly dispersed in the negative electrode system, the manufacturability of the single-walled carbon nanotubes is improved, and the conductivity of the electrode sheet is improved.
As is clear from comparative examples 1 to 3 and example 1, when only the first conductive layer 2 is disposed on both side surfaces of the substrate 1 and the second conductive layer 3 is not disposed, or when only the second conductive layer 3 is disposed on both side surfaces of the substrate 1 and the first conductive layer 2 is not disposed, or when the silicon-carbon active material 4 is not disposed in the first conductive layer 2 of the substrate 1, the expansion rate of the pole piece is improved, and the cycle efficiency is slightly reduced, mainly because the surface of the pole piece is provided with the first conductive layer 2 and/or the second conductive layer 3 containing single-walled carbon nanotubes, a sufficient expansion buffer space can be provided, and the battery failure caused by insufficient expansion space is prevented, in addition, the first conductive layer 2 contains the silicon-carbon active material 4 disposed in a dispersed manner, so that the cyclic failure caused by the expansion of the pole piece in the charge-discharge process can be effectively avoided, the second conductive layer 3 is coated on the surface of the first conductive layer 2, the expansion of the silicon-based material is buffered, the stability of the pole piece conductive network is improved, and the probability of the performance failure caused by the expansion of the pole piece is reduced. As can be seen from examples 1 and 4, when the single-walled carbon nanotubes are used as the conductive material, the expansion rate of the electrode sheet is significantly lower than that of the graphite material, and the cycle performance is also significantly improved, mainly because the single-walled carbon nanotubes can provide sufficient expansion buffer space for the silicon-based material, which is beneficial to improving the conductivity and avoiding the failure of the conductive network.
The applicant declares that the above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that are easily conceivable within the technical scope of the present invention disclosed by the present invention fall within the scope of the present invention and the disclosure.

Claims (31)

1. The preparation method of the silicon-carbon composite pole piece is characterized by comprising the following steps of:
preparing a first glue solution, dispersing single-wall carbon nanotubes in the first glue solution to obtain conductive slurry, preparing a second glue solution, and dispersing silicon carbon in the second glue solution to obtain a silicon carbon active substance;
providing a substrate, coating at least one side surface of the substrate with the conductive paste in the step (I), performing primary drying to form a first conductive layer, adopting an anilox roller to distribute the silicon-carbon active substances in the step (I) on the surface of the first conductive layer at intervals, performing secondary drying, and performing pressing to enable the silicon-carbon active substances to be completely embedded into the first conductive layer to obtain a prefabricated pole piece;
(III) coating the conductive paste in the step (I) on at least one side surface of the prefabricated pole piece in the step (II) to form a second conductive layer, so as to obtain the silicon-carbon composite pole piece;
the silicon-carbon composite pole piece comprises a matrix, wherein a first conductive layer and a second conductive layer are sequentially laminated on at least one side surface of the matrix, silicon-carbon active substances are dispersed and arranged in the first conductive layer, and the first conductive layer and the second conductive layer independently comprise single-wall carbon nanotubes.
2. The method of claim 1, wherein the substrate comprises copper foil.
3. The method of producing according to claim 2, wherein the copper foil has a thickness of 0.03 to 0.2mm.
4. The method of claim 1, wherein the single-walled carbon nanotubes have a diameter of 0.5 to 4.5nm.
5. The method according to claim 1, wherein the mass percentage of the single-walled carbon nanotubes is 0.2 to 0.8% based on 100% of the mass of the first conductive layer or the second conductive layer.
6. The method of claim 1, wherein the first conductive layer and the second conductive layer independently have a thickness of 450nm to 1800nm.
7. The method of claim 1, wherein the silicon-carbon active material comprises silicon-carbon.
8. The method according to claim 7, wherein the mass percentage of the silicon carbon active material is 63.7 to 64.4% based on 100% of the mass of the silicon carbon active material.
9. The method of claim 1, wherein in step (i), the preparing the first glue solution comprises: and mixing polyvinylidene fluoride, polyvinylpyrrolidone and N-methyl pyrrolidone, and stirring for one time to obtain the first glue solution.
10. The method according to claim 1, wherein the mass percentage of the single-walled carbon nanotubes in the conductive paste is 0.2-0.8%.
11. The method according to claim 9, wherein the mass percentage of polyvinylidene fluoride in the conductive paste is 8-10%.
12. The method according to claim 9, wherein the mass percentage of polyvinylpyrrolidone in the conductive paste is 0.6 to 1%.
13. The method according to claim 9, wherein the mass percentage of N-methylpyrrolidone in the electroconductive paste is 88.2 to 91.2%.
14. The method of claim 9, wherein in step (i), the preparing the second glue solution comprises: and mixing polyacrylic acid with deionized water, and then stirring for the second time to obtain the second glue solution.
15. The preparation method according to claim 1, wherein the silicon-carbon active material comprises 63.7-64.4% of silicon-carbon by mass.
16. The preparation method according to claim 14, wherein the mass percentage of polyacrylic acid in the silicon-carbon active material is 0.7-1.3%.
17. The method of claim 14, wherein the silicon-carbon active material comprises deionized water in an amount of 34.3-35.6% by mass.
18. The method of claim 9, wherein in step (i), the single-walled carbon nanotubes are dispersed in the first glue solution and then subjected to vacuum agitation.
19. The method of claim 18, wherein revolution speeds of the primary stirring and the primary vacuum stirring are 20 to 25rpm independently.
20. The method according to claim 18, wherein the dispersion speed of the primary stirring and the primary vacuum stirring is 2500 to 3000rpm independently.
21. The method of claim 18, wherein the one stirring time is 285 to 325 minutes.
22. The method of claim 18, wherein the one vacuum agitation is performed for a period of 285 to 325 minutes.
23. The method of claim 14, wherein in step (i), the silicon carbon is dispersed in the second glue solution and subjected to secondary vacuum agitation.
24. The method of claim 23, wherein revolution speeds of the secondary stirring and the secondary vacuum stirring are independently 20 to 25rpm.
25. The method according to claim 23, wherein the dispersion speed of the secondary stirring and the secondary vacuum stirring is 2500 to 3000rpm independently.
26. The method of claim 23, wherein the secondary stirring is performed for a period of 285 to 325 minutes.
27. The method of claim 23, wherein the secondary vacuum agitation is performed for a period of 455-515 minutes.
28. The method of claim 1, wherein in step (ii), the pressing comprises rolling.
29. The method of claim 1, wherein in step (iii), the conductive paste is applied to the surface of the prefabricated pole piece and then dried three times.
30. The preparation method according to claim 1, characterized in that the preparation method specifically comprises the following steps:
(1) Mixing polyvinylidene fluoride, polyvinylpyrrolidone and N-methyl pyrrolidone, stirring for 285-325 min for one time to obtain a first glue solution, dispersing single-walled carbon nanotubes in the first glue solution, and stirring for one time for 285-325 min in vacuum to obtain conductive slurry, wherein the conductive slurry comprises the following components in percentage by mass: 0.2 to 0.8 percent of single-wall carbon nano tube, 8 to 10 percent of polyvinylidene fluoride, 0.6 to 1 percent of polyvinylpyrrolidone and 88.2 to 91.2 percent of N-methyl pyrrolidone, wherein revolution speeds of primary stirring and primary vacuum stirring are independently 20 to 25rpm, and dispersion speeds are independently 2500 to 3000rpm;
(2) Mixing polyacrylic acid with deionized water, performing secondary stirring for 285-325 min to obtain a second glue solution, dispersing silicon carbon in the second glue solution, and performing secondary vacuum stirring for 455-515 min to obtain silicon carbon active substances, wherein the silicon carbon active substances comprise the following components in percentage by mass: 63.7 to 64.4 percent of silicon carbon, 0.7 to 1.3 percent of polyacrylic acid and 34.3 to 35.6 percent of deionized water, wherein revolution speeds of secondary stirring and secondary vacuum stirring are independently 20 to 25rpm, and dispersion speeds are independently 2500 to 3000rpm;
(3) Providing a copper foil, respectively coating the conductive paste in the step (1) on at least one side surface of the copper foil, performing primary drying to obtain a first conductive layer, adopting an anilox roller to distribute the silicon-carbon active substances in the step (2) on the surface of the first conductive layer at intervals, performing secondary drying, and then performing rolling to enable the silicon-carbon active substances to be completely embedded into the first conductive layer to obtain a prefabricated pole piece;
(4) And (3) respectively coating the conductive paste in the step (1) on at least one side surface of the prefabricated pole piece in the step (3), and then drying for three times to form a second conductive layer to obtain the silicon-carbon composite pole piece.
31. The use of a silicon-carbon composite pole piece prepared by the preparation method of any one of claims 1 to 30, wherein the silicon-carbon composite pole piece is used for preparing a lithium ion battery.
CN202210137247.2A 2022-02-15 2022-02-15 Silicon-carbon composite pole piece and preparation method and application thereof Active CN114551801B (en)

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CN109786663A (en) * 2019-01-22 2019-05-21 广东天劲新能源科技股份有限公司 Conducting resinl, using silicon-carbon cathode pole piece of the conducting resinl and preparation method thereof
CN111129427A (en) * 2019-12-24 2020-05-08 桑德新能源技术开发有限公司 Silicon-carbon cathode and preparation method thereof

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CN106560943A (en) * 2016-08-17 2017-04-12 深圳市优特利电源有限公司 Silicon-carbon negative electrode and preparation method thereof, and lithium ion battery
CN107528044A (en) * 2017-07-25 2017-12-29 深圳市沃特玛电池有限公司 A kind of lithium ion battery negative electrode and preparation method thereof
CN109786663A (en) * 2019-01-22 2019-05-21 广东天劲新能源科技股份有限公司 Conducting resinl, using silicon-carbon cathode pole piece of the conducting resinl and preparation method thereof
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