CN111916674A - Negative plate, preparation method and battery - Google Patents
Negative plate, preparation method and battery Download PDFInfo
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- CN111916674A CN111916674A CN202010772023.XA CN202010772023A CN111916674A CN 111916674 A CN111916674 A CN 111916674A CN 202010772023 A CN202010772023 A CN 202010772023A CN 111916674 A CN111916674 A CN 111916674A
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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
- H01M4/36—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
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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
- 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
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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
- H01M4/134—Electrodes based on metals, Si or alloys
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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
- H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
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- 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 negative plate, a preparation method and a battery, wherein the negative plate comprises: a current collector; the active layer is arranged on the current collector and comprises silicon particles with ion exchange layers coated on the surfaces; the modification layer is arranged on one side, far away from the current collector, of the active layer. In the negative plate, the ion exchange layer is coated on the silicon particles, the ion exchange layer has good ionic conductivity and can modify the silicon particles, the coating of the ion exchange layer on the surface of the silicon particles is favorable for reducing the contact between the silicon particles and electrolyte, so that the interface side reaction is reduced, the larger volume expansion of the silicon particles can be inhibited, the silicon particles are prevented from separating from a current collector due to expansion, the modification layer can improve the tensile strength of the negative plate, prevent silicon powder from falling off, prevent capacity attenuation, improve the charge-discharge efficiency, improve the cycle performance of the negative plate and prolong the service life of the negative plate.
Description
Technical Field
The invention relates to the technical field of batteries, in particular to a negative plate, a preparation method and a battery.
Background
The lithium ion battery is widely applied to the fields of electronic equipment, electric appliances, electric automobiles and the like as an efficient, light and portable energy storage device. The large volume expansion of silicon as a negative electrode material during charge-discharge cycles limits the amount of silicon negative electrode used. The root of the volume expansion of the silicon negative electrode lies in that silicon continuously forms a new SEI layer in the charging and discharging process, an old SEI layer is continuously broken, and silicon is seriously pulverized, so that the larger volume expansion of the silicon negative electrode material is caused, nano silicon is separated from a current collector due to expansion, the capacity attenuation is further caused, and the charge and discharge efficiency of the nano silicon is low due to the poor conductivity of the nano silicon, so that the cycle performance and the service life of a pole piece are reduced.
Disclosure of Invention
In view of the above, the invention provides a negative plate, a preparation method and a battery, which are used for solving the problems of capacity attenuation, low charge and discharge efficiency, low cycle performance of the negative plate and short service life caused by large volume expansion of a silicon negative electrode material and easy separation from a current collector.
In order to solve the technical problems, the invention adopts the following technical scheme:
in a first aspect, a negative electrode sheet according to an embodiment of the present invention includes:
a current collector;
the active layer is arranged on the current collector and comprises silicon particles with ion exchange layers coated on the surfaces;
the modification layer is arranged on one side, far away from the current collector, of the active layer.
Wherein the particle size of the silicon particles is 10nm-1000 nm.
Wherein the thickness of the ion exchange layer is 1nm-10 μm; and/or
The thickness of the modification layer is 1nm-10 mu m.
Wherein, the silicon particles in the active layer account for 20-90% of the mass fraction of the active layer, and the ion exchange layer in the active layer accounts for 1-50% of the mass fraction of the active layer.
Wherein the ion exchange layer is a perfluorosulfonic acid resin layer; and/or
The modification layer is a perfluorosulfonic acid resin layer.
Wherein the active layer further comprises a conductive agent.
Wherein the active layer further comprises at least one of a binder, a dispersant or a thickener.
Wherein the binder comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyethyleneimine, polyaniline, polyacrylic acid, sodium alginate, styrene butadiene rubber, sodium carboxymethylcellulose, phenolic resin or epoxy resin; and/or
The dispersing agent comprises one or more of polypropylene, hexadecyl ammonium bromide, sodium dodecyl benzene sulfonate or silane coupling agent, ethanol, N-methyl pyrrolidone and N, N-dimethylformamide; and/or
The thickening agent comprises at least one of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, hydroxymethyl cellulose and sodium hydroxymethyl cellulose.
In a second aspect, a method for preparing a negative electrode sheet according to an embodiment of the present invention includes:
providing a current collector;
forming an active layer on the current collector, wherein the active layer comprises silicon particles with ion exchange layers coated on the surfaces;
and forming a modification layer on one side of the active layer, which is far away from the current collector, so as to obtain the negative plate.
In a third aspect, a battery according to an embodiment of the present invention includes the negative electrode tab described in the above embodiment.
The technical scheme of the invention has the following beneficial effects:
according to the negative plate provided by the embodiment of the invention, the active layer is arranged on the current collector and comprises silicon particles with ion exchange layers coated on the surfaces, and the modification layer is arranged on one side of the active layer, which is far away from the current collector. In the negative plate, the ion exchange layer is coated on the silicon particles, the ion exchange layer has good ionic conductivity and can modify the silicon particles, the coating of the ion exchange layer on the surface of the silicon particles is favorable for reducing the contact between the silicon particles and electrolyte, so that the interface side reaction is reduced, the larger volume expansion of the silicon particles can be inhibited, the silicon particles are prevented from separating from a current collector due to expansion, the modification layer can improve the tensile strength of the negative plate, prevent silicon powder from falling off, prevent capacity attenuation, improve the charge-discharge efficiency, improve the cycle performance of the negative plate and prolong the service life of the negative plate.
Drawings
Fig. 1 is a schematic structural view of a negative electrode sheet according to an embodiment of the present invention.
Reference numerals
A current collector 10;
a finishing layer 30.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention, are within the scope of the invention.
The negative electrode sheet according to an embodiment of the present invention is described in detail below.
As shown in fig. 1, the negative electrode sheet according to the embodiment of the present invention includes a current collector 10, an active layer and a modification layer 30, wherein the active layer is disposed on the current collector 10, the active layer includes silicon particles 21 with an ion exchange layer 22 coated on the surface, and the modification layer 30 is disposed on a side of the active layer away from the current collector 10.
That is to say, the negative plate mainly comprises a current collector 10, an active layer and a modification layer 30, wherein the current collector 10 may be a copper foil, the current collector 10 may be a copper foil with a thickness of 6 μm, the active layer may be disposed on one side surface of the current collector 10, the active layer includes silicon particles 21 with an ion exchange layer 22 coated on the surface, the silicon particles 21 in the active layer may be uniformly dispersed, the ion exchange layer 22 may have good ionic conductivity, the ion exchange layer 22 may exchange cations, for example, the ion exchange layer 22 may exchange hydrogen ions, lithium ions, sodium ions, potassium ions, and the like, the ion exchange layer 22 may be a polymer layer, the ion exchange layer 22 may also have certain elasticity, the silicon particles 21 coated by the ion exchange layer 22 may inhibit expansion of the silicon particles 21, the modification layer 30 may be disposed on one side of the active layer away from the current collector 10, the modification layer 30 may be a uniform film layer, effectively prevent the pole piece inflation, can be for having the rete of high tensile strength, modification layer 30 can further improve the tensile strength of negative pole piece, prevents that silica flour from droing.
In the negative plate, the ion exchange layer is coated on the silicon particles, the ion exchange layer has good ionic conductivity and can modify the silicon particles, the coating of the ion exchange layer on the surface of the silicon particles is favorable for reducing the contact between the silicon particles and electrolyte, so that the interface side reaction is reduced, the larger volume expansion of the silicon particles can be inhibited, the silicon particles are prevented from separating from a current collector due to expansion, the modification layer can improve the tensile strength of the negative plate, prevent silicon powder from falling off, prevent capacity attenuation, improve the charge-discharge efficiency, improve the cycle performance of the negative plate and prolong the service life of the negative plate. The cathode plate provided by the invention is suitable for various materials and various combination modes, is favorable for reducing the preparation cost and large-scale production, and is favorable for commercial development.
In some embodiments of the present invention, the silicon particles 21 may have a particle size of 10nm to 1000 nm.
In other embodiments of the present invention, the thickness of the ion exchange layer 22 may be 1nm to 10 μm, for example, the thickness of the ion exchange layer 22 may be 1nm or 10 μm; and/or, the thickness of the modification layer 30 may be 1nm-10 μm, for example, the thickness of the modification layer 30 may be 1nm or 10 μm, and the specific thickness may be selected according to actual needs. The thickness of the negative electrode sheet may be 10 μm to 500 μm, and the thickness of the current collector 10 may be 1 μm to 50 μm, and those skilled in the art can set the thicknesses of the active layer and the current collector within the above thickness range in combination with actual needs.
In the embodiment of the invention, the silicon particles 21 in the active layer account for 20-90% of the mass fraction of the active layer, and the ion exchange layer 22 in the active layer accounts for 1-50% of the mass fraction of the active layer, for example, the silicon particles 21 in the active layer account for 90% of the mass fraction of the active layer, and the ion exchange layer 22 in the active layer accounts for 6% of the mass fraction of the active layer; the silicon particles 21 in the active layer account for 20% of the mass fraction of the active layer, and the ion exchange layer 22 in the active layer accounts for 1% of the mass fraction of the active layer, and the specific content can be selected according to the needs. One of a conductive agent, a binder, a dispersant or a thickener can be added to the active layer as required, and the specific content can be selected reasonably. The content of the binder can be 0.1-10% of the mass of the active layer.
In some embodiments of the invention, the ion exchange layer 22 may be a layer of perfluorosulfonic acid resin (Nafion); and/or, the finishing layer 30 may be a layer of perfluorosulfonic acid resin. The perfluorinated sulfonic acid resin layer can exchange ions, such as lithium ions, has certain elasticity, can buffer the expansion of silicon particles, prevents the silicon particles from powdering and falling off, and the perfluorinated sulfonic acid resin layer also has the bonding effect to bond the silicon particles together, so that the connection between the nano silicon particles is enhanced, the powdering and falling off are prevented, the toughness of the pole piece is improved, and the pole piece is not easy to break.
Optionally, the active layer may further include a conductive agent, and the conductive agent may include one or more of Carbon Nanotubes (CNTs), carbon fibers (VGCF), conductive graphite, mesocarbon microbeads (MCMB), graphene, ketjen black, acetylene black, conductive carbon black, hard carbon, or metal powder.
According to some embodiments, the active layer may further include at least one of a binder, a dispersant, or a thickener. The binder can comprise one or more of polyvinylidene fluoride (PVDF), Polytetrafluoroethylene (PTFE), Polyethyleneimine (PEI), Polyaniline (PAN), polyacrylic acid (PAA), sodium alginate, Styrene Butadiene Rubber (SBR), sodium carboxymethylcellulose (CMC), phenolic resin or epoxy resin, and has a good binding effect; and/or, the dispersant may include one or more of Polypropylene (PVA), cetyl ammonium bromide, sodium dodecylbenzene sulfonate or silane coupling agent, ethanol, N-methyl pyrrolidone (NMP), N-Dimethylformamide (DMF), to facilitate uniform dispersion; and/or, the thickener may include at least one of sodium carboxymethylcellulose, lithium carboxymethylcellulose, hydroxymethylcellulose, sodium hydroxymethylcellulose, facilitating the application of the active coating.
The embodiment of the invention provides a preparation method of a negative plate, which comprises the following steps:
providing a current collector 10;
forming an active layer on the current collector 10, wherein the active layer comprises silicon particles 21 with ion exchange layers 22 coated on the surfaces;
and forming a modification layer 30 on the side of the active layer far away from the current collector 10 to obtain the negative plate.
That is to say, selecting a suitable current collector 10, forming an active layer on one side surface of the current collector 10, wherein the active layer may include silicon particles 21 whose surfaces are coated with ion exchange layers 22, the silicon particles 21 in the active layer may be uniformly dispersed, and forming a modification layer 30 on one side of the active layer away from the current collector 10, so as to obtain the negative electrode sheet. The current collector 10 may be a copper foil, the ion exchange layer 22 may have good ionic conductivity, the ion exchange layer 22 may exchange cations, for example, the ion exchange layer 22 may exchange hydrogen ions, lithium ions, sodium ions, potassium ions, and the like, the ion exchange layer 22 may be a polymer layer, the ion exchange layer 22 may also have certain elasticity, and the silicon particles 21 are coated by the ion exchange layer 22 to inhibit expansion of the silicon particles 21; the modification layer 30 can be arranged on one side of the active layer far away from the current collector 10, and the modification layer 30 can further improve the tensile strength of the negative plate and prevent silicon powder from falling off. In the negative plate prepared by the preparation method, the ion exchange layer coats the silicon particles, the ion exchange layer has good ionic conductivity, the silicon particles can be modified, the surface of the silicon particles is coated with the ion exchange layer, the silicon particles are favorably reduced to be contacted with electrolyte, so that interface side reaction is reduced, large volume expansion of the silicon particles can be inhibited, the silicon particles are prevented from being separated from a current collector due to expansion, the modification layer can improve the tensile strength of the negative plate, silicon powder is prevented from falling off, capacity attenuation is prevented, the charge and discharge efficiency is improved, and the cycle performance and the service life of the negative plate are improved.
Wherein the step of forming the active layer on the current collector 10 may include: coating the coating that contains the silicon particle on one side surface of mass flow body, coating perfluor sulfonic acid resin solution on the coating, perfluor sulfonic acid resin solution can permeate into in the coating in order to fill between the silicon particle, the surface cladding at the silicon particle has perfluor sulfonic acid resin in order to form the perfluor sulfonic acid resin layer, and then forms the active layer, avoided leading to nanometer silicon particle to reunite because the cladding in-process to cause the dispersion relatively poor capacity that is unfavorable for the silicon particle to exert, can effectively prevent the pole piece pulverization pole piece that the pole piece fracture arouses serious. In addition, the perfluorinated sulfonic acid resin can also form a modification layer on one side of the active layer, which is far away from the current collector, so that the flexibility of the pole piece is enhanced, and the pole piece pulverization and falling off are reduced.
In some embodiments of the present invention, the silicon particles 21 may have a particle size of 10nm to 1000 nm.
Alternatively, the thickness of the ion exchange layer 22 may be 1nm to 10 μm, for example, the thickness of the ion exchange layer 22 may be 1nm or 10 μm; and/or, the thickness of the modification layer 30 may be 1nm-10 μm, for example, the thickness of the modification layer 30 may be 1nm or 10 μm, and the specific thickness may be selected according to actual needs.
In the embodiment of the invention, the silicon particles 21 in the active layer account for 20-90% of the mass fraction of the active layer, and the ion exchange layer 22 in the active layer accounts for 1-50% of the mass fraction of the active layer, for example, the silicon particles 21 in the active layer account for 90% of the mass fraction of the active layer, and the ion exchange layer 22 in the active layer accounts for 6% of the mass fraction of the active layer.
Alternatively, the ion exchange layer 22 may be a layer of perfluorosulfonic acid resin; and/or, the finishing layer 30 may be a layer of perfluorosulfonic acid resin. The perfluorinated sulfonic acid resin layer can exchange ions such as lithium ions, has certain elasticity, can buffer the expansion of silicon particles, prevents the silicon particles from being pulverized and falling off, and has a bonding effect to bond the silicon particles together and prevent the pulverization and the falling off.
Optionally, the active layer may further include a conductive agent, and the conductive agent may include one or more of carbon nanotubes, carbon fibers, conductive graphite, mesocarbon microbeads, graphene, ketjen black, acetylene black, conductive carbon black, hard carbon, or metal powder. According to some embodiments, the active layer may further include at least one of a binder, a dispersant, or a thickener. Wherein, the binder can comprise one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyethyleneimine, polyaniline, polyacrylic acid (PAA), sodium alginate, styrene butadiene rubber, sodium carboxymethylcellulose, phenolic resin or epoxy resin, and has better binding effect; and/or, the dispersant may include one or more of Polypropylene (PVA), cetyl ammonium bromide, sodium dodecylbenzene sulfonate or silane coupling agent, ethanol, N-methyl pyrrolidone (NMP), N-Dimethylformamide (DMF), to facilitate uniform dispersion; and/or, the thickener may include at least one of sodium carboxymethylcellulose (CMC), lithium carboxymethylcellulose, hydroxymethylcellulose, sodium hydroxymethylcellulose, facilitating the application of the active coating.
In the practical application process, the preparation method of the negative plate can be as follows:
step 1, respectively weighing nano silicon particles with certain mass, and a binder, a dispersant, a conductive agent, a thickening agent and water which are required in active layer slurry;
step 2, adding a thickening agent into water with a half formula amount, then sequentially adding a binder, a dispersing agent, a conductive agent and nano silicon particles under the stirring condition, uniformly dispersing, adding the rest of water, and then grinding and sieving to obtain nano silicon active layer slurry;
and 3, coating the prepared nano silicon active layer slurry in a current collector to form a slurry layer, drying, coating a perfluorinated sulfonic acid resin solution on one side of the slurry layer, which is far away from the current collector, wherein the perfluorinated sulfonic acid resin solution can penetrate into the slurry layer to fill among silicon particles in the slurry layer, coating perfluorinated sulfonic acid resin on the surfaces of the silicon particles to form a perfluorinated sulfonic acid resin layer, drying, rolling and cutting the pieces to obtain the cathode piece.
The negative plate prepared above, the positive plate, the electrolyte and the diaphragm can be assembled into a battery, such as a lithium ion battery. The positive electrode material in the positive plate can be lithium cobaltate, lithium iron phosphate, lithium manganate, lithium nickelate, lithium nickel cobalt manganese activated lithium nickel cobalt aluminate and the like.
An embodiment of the present invention provides a battery, which includes the negative electrode sheet described in the above embodiment. The battery with the negative plate can inhibit the larger volume expansion of silicon particles, prevent the silicon particles from separating from a current collector due to expansion, improve capacity attenuation, improve charge and discharge efficiency, have higher energy density, and have better cycle performance and service life.
The invention is further illustrated by the following specific examples.
Example 1
The preparation method of the negative electrode plate provided by the embodiment comprises the following steps:
weighing 80g of nano silicon particles, and preparing silicon active layer slurry by matching with 10g of binder PAA, 2g of dispersant sodium dodecyl benzene sulfonate, 4g of conductive agent carbon nano tube, 4g of thickener CMC and 100g of water; specifically, firstly adding a thickening agent CMC into water with a half formula amount, then sequentially adding a binder PAA, a dispersant sodium dodecyl benzene sulfonate, a conductive agent carbon nano tube and pure nano silicon particles under the stirring condition, uniformly dispersing, then adding the rest water, and then grinding and sieving to obtain silicon particle active layer slurry;
coating the prepared silicon particle active layer slurry on a current collector to form a slurry layer, wherein the size of a coating area is 47mm x 65mm, the thickness is 100 mu m after drying, coating perfluorinated sulfonic acid resin solution on one side of the slurry layer, which is far away from the current collector, coating 3ml of perfluorinated sulfonic acid resin solution, infiltrating the perfluorinated sulfonic acid resin solution into the slurry layer to fill the space between the silicon particles in the slurry layer, coating perfluorinated sulfonic acid resin on the surfaces of the silicon particles to form a perfluorinated sulfonic acid resin layer, and rolling and cutting the silicon particles after drying to obtain the negative plate.
Example 2
The preparation method of the negative electrode plate provided by the embodiment comprises the following steps:
weighing 80g of nano silicon particles, and preparing silicon active layer slurry by matching with 10g of binder PAA, 2g of dispersant sodium dodecyl benzene sulfonate, 4g of conductive agent carbon nano tube, 4g of thickener CMC and 100g of water; specifically, firstly adding a thickening agent CMC into water with a half formula amount, then sequentially adding a binder PAA, a dispersant sodium dodecyl benzene sulfonate, a conductive agent carbon nano tube and pure nano silicon particles under the stirring condition, uniformly dispersing, then adding the rest water, and then grinding and sieving to obtain silicon particle active layer slurry;
coating the prepared silicon particle active layer slurry on a current collector to form a slurry layer, wherein the size of a coating area is 47mm x 65mm, the thickness is 80 mu m after drying, coating perfluorinated sulfonic acid resin solution on one side of the slurry layer, which is far away from the current collector, coating 3ml of perfluorinated sulfonic acid resin solution, infiltrating the perfluorinated sulfonic acid resin solution into the slurry layer to fill the space between the silicon particles in the slurry layer, coating perfluorinated sulfonic acid resin on the surfaces of the silicon particles to form a perfluorinated sulfonic acid resin layer, and rolling and cutting the silicon particles after drying to obtain the negative plate.
Example 3
The preparation method of the negative electrode plate provided by the embodiment comprises the following steps:
weighing 80g of nano silicon particles, and preparing silicon active layer slurry by matching with 10g of binder PAA, 2g of dispersant sodium dodecyl benzene sulfonate, 4g of conductive agent carbon nano tube, 4g of thickener CMC and 100g of water; specifically, firstly adding a thickening agent CMC into water with a half formula amount, then sequentially adding a binder PAA, a dispersant sodium dodecyl benzene sulfonate, a conductive agent carbon nano tube and pure nano silicon particles under the stirring condition, uniformly dispersing, then adding the rest water, and then grinding and sieving to obtain silicon particle active layer slurry;
coating the prepared silicon particle active layer slurry on a current collector to form a slurry layer, wherein the size of a coating area is 47mm x 65mm, the thickness is 50 mu m after drying, coating perfluorinated sulfonic acid resin solution on one side of the slurry layer, which is far away from the current collector, coating 3ml of perfluorinated sulfonic acid resin solution, infiltrating the perfluorinated sulfonic acid resin solution into the slurry layer to fill the space between the silicon particles in the slurry layer, coating perfluorinated sulfonic acid resin on the surfaces of the silicon particles to form a perfluorinated sulfonic acid resin layer, and rolling and cutting the silicon particles after drying to obtain the negative plate.
Example 4
The preparation method of the negative electrode plate provided by the embodiment comprises the following steps:
weighing 80g of nano silicon particles, and preparing silicon active layer slurry by matching with 10g of binder PAA, 2g of dispersant sodium dodecyl benzene sulfonate, 4g of conductive agent carbon nano tube, 4g of thickener CMC and 100g of water; specifically, firstly adding a thickening agent CMC into water with a half formula amount, then sequentially adding a binder PAA, a dispersant sodium dodecyl benzene sulfonate, a conductive agent carbon nano tube and pure nano silicon particles under the stirring condition, uniformly dispersing, then adding the rest water, and then grinding and sieving to obtain silicon particle active layer slurry;
coating the prepared silicon particle active layer slurry on a current collector to form a slurry layer, wherein the size of a coating area is 47mm x 65mm, the thickness is 30 mu m after drying, coating perfluorinated sulfonic acid resin solution on one side of the slurry layer, which is far away from the current collector, coating 3ml of perfluorinated sulfonic acid resin solution, infiltrating the perfluorinated sulfonic acid resin solution into the slurry layer to fill the space between the silicon particles in the slurry layer, coating perfluorinated sulfonic acid resin on the surfaces of the silicon particles to form a perfluorinated sulfonic acid resin layer, and rolling and cutting the silicon particles after drying to obtain the negative plate.
Example 5
The preparation method of the negative electrode plate provided by the embodiment comprises the following steps:
weighing 80g of nano silicon particles, and preparing silicon active layer slurry by matching with 10g of binder PAA, 2g of dispersant sodium dodecyl benzene sulfonate, 4g of conductive agent carbon nano tube, 4g of thickener CMC and 100g of water; specifically, firstly adding a thickening agent CMC into water with a half formula amount, then sequentially adding a binder PAA, a dispersant sodium dodecyl benzene sulfonate, a conductive agent carbon nano tube and pure nano silicon particles under the stirring condition, uniformly dispersing, then adding the rest water, and then grinding and sieving to obtain silicon particle active layer slurry;
coating the prepared silicon particle active layer slurry on a current collector to form a slurry layer, wherein the size of a coating area is 47mm x 65mm, the thickness is 100 mu m after drying, coating perfluorinated sulfonic acid resin solution on one side of the slurry layer, which is far away from the current collector, coating 5ml of perfluorinated sulfonic acid resin solution, infiltrating the perfluorinated sulfonic acid resin solution into the slurry layer to fill the space between the silicon particles in the slurry layer, coating perfluorinated sulfonic acid resin on the surfaces of the silicon particles to form a perfluorinated sulfonic acid resin layer, and rolling and cutting the silicon particles after drying to obtain the negative plate.
Example 6
The preparation method of the negative electrode plate provided by the embodiment comprises the following steps:
weighing 80g of nano silicon particles, and preparing silicon active layer slurry by matching with 10g of binder PAA, 2g of dispersant sodium dodecyl benzene sulfonate, 4g of conductive agent carbon nano tube, 4g of thickener CMC and 100g of water; specifically, firstly adding a thickening agent CMC into water with a half formula amount, then sequentially adding a binder PAA, a dispersant sodium dodecyl benzene sulfonate, a conductive agent carbon nano tube and pure nano silicon particles under the stirring condition, uniformly dispersing, then adding the rest water, and then grinding and sieving to obtain silicon particle active layer slurry;
coating the prepared silicon particle active layer slurry on a current collector to form a slurry layer, wherein the size of a coating area is 47mm x 65mm, the thickness is 80 mu m after drying, coating perfluorinated sulfonic acid resin solution on one side of the slurry layer, which is far away from the current collector, coating 7ml of perfluorinated sulfonic acid resin solution, infiltrating the perfluorinated sulfonic acid resin solution into the slurry layer to fill the space between the silicon particles in the slurry layer, coating perfluorinated sulfonic acid resin on the surfaces of the silicon particles to form a perfluorinated sulfonic acid resin layer, and rolling and cutting the silicon particles after drying to obtain the negative plate.
Example 7
The preparation method of the negative electrode plate provided by the embodiment comprises the following steps:
weighing 80g of nano silicon particles, and preparing silicon active layer slurry by matching with 10g of binder PAA, 2g of dispersant sodium dodecyl benzene sulfonate, 4g of conductive agent carbon nano tube, 4g of thickener CMC and 100g of water; specifically, firstly adding a thickening agent CMC into water with a half formula amount, then sequentially adding a binder PAA, a dispersant sodium dodecyl benzene sulfonate, a conductive agent carbon nano tube and pure nano silicon particles under the stirring condition, uniformly dispersing, then adding the rest water, and then grinding and sieving to obtain silicon particle active layer slurry;
coating the prepared silicon particle active layer slurry on a current collector to form a slurry layer, wherein the size of a coating area is 47mm x 65mm, the thickness is 100 mu m after drying, coating perfluorinated sulfonic acid resin solution on one side of the slurry layer, which is far away from the current collector, coating 10ml of perfluorinated sulfonic acid resin solution, infiltrating the perfluorinated sulfonic acid resin solution into the slurry layer to fill the space between the silicon particles in the slurry layer, coating perfluorinated sulfonic acid resin on the surfaces of the silicon particles to form a perfluorinated sulfonic acid resin layer, and rolling and cutting the silicon particles after drying to obtain the negative plate.
Example 8
The preparation method of the negative electrode plate provided by the embodiment comprises the following steps:
weighing 80g of nano silicon particles, and preparing silicon active layer slurry by matching with 10g of binder PAA, 2g of dispersant sodium dodecyl benzene sulfonate, 4g of conductive agent carbon nano tube, 4g of thickener CMC and 100g of water; specifically, firstly adding a thickening agent CMC into water with a half formula amount, then sequentially adding a binder PAA, a dispersant sodium dodecyl benzene sulfonate, a conductive agent carbon nano tube and pure nano silicon particles under the stirring condition, uniformly dispersing, then adding the rest water, and then grinding and sieving to obtain silicon particle active layer slurry;
coating the prepared silicon particle active layer slurry on a current collector to form a slurry layer, wherein the size of a coating area is 47mm x 65mm, the thickness is 100 mu m after drying, coating perfluorinated sulfonic acid resin solution on one side of the slurry layer, which is far away from the current collector, coating 1ml of perfluorinated sulfonic acid resin solution, infiltrating the perfluorinated sulfonic acid resin solution into the slurry layer to fill the space between the silicon particles in the slurry layer, coating perfluorinated sulfonic acid resin on the surfaces of the silicon particles to form a perfluorinated sulfonic acid resin layer, and rolling and cutting the silicon particles after drying to obtain the negative plate.
Example 9
The preparation method of the negative electrode plate provided by the embodiment comprises the following steps:
weighing 80g of nano silicon particles, and preparing silicon active layer slurry by matching with 10g of binder PAA, 2g of dispersant sodium dodecyl benzene sulfonate, 4g of conductive agent carbon nano tube, 4g of thickener CMC and 100g of water; specifically, firstly adding a thickening agent CMC into water with a half formula amount, then sequentially adding a binder PAA, a dispersant sodium dodecyl benzene sulfonate, a conductive agent carbon nano tube and pure nano silicon particles under the stirring condition, uniformly dispersing, then adding the rest water, and then grinding and sieving to obtain silicon particle active layer slurry;
coating the prepared silicon particle active layer slurry on a current collector to form a slurry layer, wherein the size of a coating area is 47mm x 65mm, the thickness is 100 mu m after drying, coating perfluorinated sulfonic acid resin solution on one side of the slurry layer, which is far away from the current collector, coating 0.5ml of perfluorinated sulfonic acid resin solution, infiltrating the perfluorinated sulfonic acid resin solution into the slurry layer to fill the space between silicon particles in the slurry layer, coating perfluorinated sulfonic acid resin on the surfaces of the silicon particles to form a perfluorinated sulfonic acid resin layer, and rolling and cutting the plates after drying to obtain the negative plate.
Example 10
The preparation method of the negative electrode plate provided by the embodiment comprises the following steps:
weighing 80g of nano silicon particles, and preparing silicon active layer slurry by matching with 10g of binder PAA, 2g of dispersant sodium dodecyl benzene sulfonate, 4g of conductive agent carbon nano tube, 4g of thickener CMC and 100g of water; specifically, firstly adding a thickening agent CMC into water with a half formula amount, then sequentially adding a binder PAA, a dispersant sodium dodecyl benzene sulfonate, a conductive agent carbon nano tube and pure nano silicon particles under the stirring condition, uniformly dispersing, then adding the rest water, and then grinding and sieving to obtain silicon particle active layer slurry;
coating the prepared silicon particle active layer slurry on a current collector to form a slurry layer, wherein the size of a coating area is 47mm x 65mm, the thickness is 100 mu m after drying, coating perfluorinated sulfonic acid resin solution on one side of the slurry layer, which is far away from the current collector, coating 0.2ml of perfluorinated sulfonic acid resin solution, infiltrating the perfluorinated sulfonic acid resin solution into the slurry layer to fill the space between silicon particles in the slurry layer, coating perfluorinated sulfonic acid resin on the surfaces of the silicon particles to form a perfluorinated sulfonic acid resin layer, and rolling and cutting the plates after drying to obtain the negative plate.
Comparative example 1
The preparation method of the negative plate provided by the comparative example comprises the following steps:
weighing 80g of nano silicon particles, and preparing slurry by matching with 10g of binder PAA, 2g of dispersant sodium dodecyl benzene sulfonate, 4g of conductive agent carbon nano tube, 4g of thickener CMC and 100g of water; specifically, adding a thickening agent CMC into water with a half formula amount, then sequentially adding a binder PAA, a dispersant sodium dodecyl benzene sulfonate, a conductive agent carbon nano tube and pure nano silicon particles under a stirring condition, adding the rest water after uniformly dispersing, and then grinding and sieving to obtain slurry;
coating the prepared slurry on a current collector to form a slurry layer, wherein the size of a coating area is 47mm x 65mm, the thickness is 100 mu m after drying, the thickness of the slurry layer is 94 mu m, and the negative plate is obtained after drying, rolling and cutting.
Comparative example 2: comparative example 2 is different from comparative example 1 in that the thickness of the slurry layer is 80 μm.
Comparative example 3: comparative example 3 is different from comparative example 1 in that the thickness of the slurry layer is 50 μm.
Comparative example 4: comparative example 4 is different from comparative example 1 in that the thickness of the slurry layer is 30 μm.
The negative electrode sheets prepared in examples 1 to 10 and comparative examples 1 to 4 were assembled with a lithium cobaltate positive electrode sheet, an electrolyte, a separator, and an aluminum plastic film to form a laminated lithium ion battery. Wherein, the particle size of the nano silicon particles in examples 1 to 10 and comparative examples 1 to 4 can be 50 to 200nm, a Polyethylene (PE) porous diaphragm is used as the diaphragm, and the thickness of the diaphragm is 12 μm; the electrolyte is a carbonate solution, and the main additives are VC and FEC; the positive electrode material is lithium cobaltate, and the voltage range of the lithium cobaltate is 3.0-4.45V. The lithium ion batteries manufactured in examples 1 to 10 and comparative examples 1 to 4 were tested for the number of cycles for capacity fade to 80% of the initial capacity at 25C, 0.5C/0.5C energy density, and the expansion rate of the electrode sheet after 100 cycles, and the test results are shown in table 1.
TABLE 1 test results
| Energy Density (Wh/L) | Number of cycles | Expansion rate of pole piece | |
| Example 1 | 956 | 209 | 148％ |
| Example 2 | 870 | 228 | 125％ |
| Example 3 | 839 | 274 | 83％ |
| Example 4 | 801 | 352 | 66％ |
| Example 5 | 903 | 235 | 129％ |
| Example 6 | 893 | 283 | 93％ |
| Example 7 | 880 | 302 | 78％ |
| Example 8 | 937 | 167 | 186％ |
| Example 9 | 927 | 123 | 237％ |
| Example 10 | 916 | 104 | 256％ |
| Comparative example 1 | 894 | 69 | 302％ |
| Comparative example 2 | 863 | 72 | 298％ |
| Comparative example 3 | 855 | 74 | 283％ |
| Comparative example 4 | 825 | 76 | 277％ |
From the test results of examples 1 to 4 in table 1, it can be seen that the content of the perfluorosulfonic acid resin is controlled, the thickness of the nano silicon particle pole piece is reduced, the energy density is reduced, but the expansion rate is inhibited more obviously, and the cycle number is increased significantly; from the test results of examples 5-7, it can be seen that the thickness of the nano-silicon particle pole piece is unchanged, the content of the perfluorosulfonic acid resin is increased, the cycle number is increased, the energy reduction is not obvious, and the cycle expansion is reduced; the test results of the examples 8 to 10 show that the content of the coated perfluorosulfonic acid resin is reduced, the expansion rate of the pole piece is increased, the cycle number is reduced, and the energy density is reduced; the test results of the examples 1 to 10 and the comparative examples 1 to 4 are combined to show that the perfluorinated sulfonic acid resin is coated on the surface of the pole piece and penetrates into the surface of the nano silicon particle to form a coating layer, so that the surface of the silicon particle in the negative pole piece is coated with the perfluorinated sulfonic acid resin layer, and a modification layer is formed on the surface of the active layer, so that the cycle number can be increased, and the improvement of the energy density of the battery and the inhibition of the volume expansion of the nano silicon particle are facilitated.
Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," and similar terms in the present application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships are changed accordingly.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. A negative electrode sheet, comprising:
a current collector;
the active layer is arranged on the current collector and comprises silicon particles with ion exchange layers coated on the surfaces;
the modification layer is arranged on one side, far away from the current collector, of the active layer.
2. The negative electrode sheet according to claim 1, wherein the silicon particles have a particle size of 10nm to 1000 nm.
3. The negative electrode sheet according to claim 1, wherein the thickness of the ion exchange layer is 1nm to 10 μm; and/or
The thickness of the modification layer is 1nm-10 mu m.
4. The negative electrode sheet according to claim 1, wherein the silicon particles in the active layer account for 20-90% of the mass fraction of the active layer, and the ion exchange layer in the active layer accounts for 1-50% of the mass fraction of the active layer.
5. A negative electrode sheet according to claim 1, wherein the ion exchange layer is a layer of perfluorosulfonic acid resin; and/or
The modification layer is a perfluorosulfonic acid resin layer.
6. A negative electrode sheet according to claim 1, wherein said active layer further comprises a conductive agent.
7. The negative electrode sheet of claim 1, wherein the active layer further comprises at least one of a binder, a dispersant, or a thickener.
8. The negative electrode sheet of claim 7, wherein the binder comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyethyleneimine, polyaniline, polyacrylic acid, sodium alginate, styrene-butadiene rubber, sodium carboxymethylcellulose, phenolic resin, or epoxy resin; and/or
The dispersing agent comprises one or more of polypropylene, hexadecyl ammonium bromide, sodium dodecyl benzene sulfonate or silane coupling agent, ethanol, N-methyl pyrrolidone and N, N-dimethylformamide; and/or
The thickening agent comprises at least one of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, hydroxymethyl cellulose and sodium hydroxymethyl cellulose.
9. A preparation method of a negative plate is characterized by comprising the following steps:
providing a current collector;
forming an active layer on the current collector, wherein the active layer comprises silicon particles with ion exchange layers coated on the surfaces;
and forming a modification layer on one side of the active layer, which is far away from the current collector, so as to obtain the negative plate.
10. A battery comprising the negative electrode sheet according to any one of claims 1 to 8.
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