CN111640901A - Preparation method of lithium ion battery diaphragm, lithium ion battery and preparation method thereof - Google Patents
Preparation method of lithium ion battery diaphragm, lithium ion battery and preparation method thereof Download PDFInfo
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- CN111640901A CN111640901A CN202010455715.1A CN202010455715A CN111640901A CN 111640901 A CN111640901 A CN 111640901A CN 202010455715 A CN202010455715 A CN 202010455715A CN 111640901 A CN111640901 A CN 111640901A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D1/00—Processes for applying liquids or other fluent materials
- B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
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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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
- H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
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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
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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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
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Abstract
The invention discloses a preparation method of a lithium ion battery diaphragm, a lithium ion battery and a preparation method thereof, wherein the preparation method comprises the following steps: (1) preparing a sizing agent with caking property; (2) spraying the slurry obtained in the step (1) onto a rotating disc through a spraying device, throwing the slurry out of the rotating disc to flow through a regulating area to one side or two sides of a ceramic diaphragm so as to form a uniformly distributed slurry attaching area and a slurry non-attaching area, wherein the surface density of the slurry attached to the surface of the ceramic diaphragm is 0.2g/m2～1g/m2(ii) a (3) And (3) coating and drying the ceramic diaphragm with the slurry in the step (2) to obtain the lithium ion battery diaphragm. The preparation method of the lithium ion battery diaphragm of the invention comprises the following stepsThe thick liquids transfer to rotatory disc on, the disc becomes the dribble with thick liquids homodisperse and gets rid of to ceramic diaphragm surface, because thick liquids are local even adhesion, and the thick liquids non-adheres to the district and gives lithium cell utmost point inflation and provide the inflation space, prevents that lithium cell pole piece thermal expansion and ceramic diaphragm from taking place the staggered floor.
Description
Technical Field
The invention relates to the field of battery diaphragms, in particular to a preparation method of a lithium ion battery diaphragm. In addition, the invention also relates to a lithium ion battery comprising the preparation method of the lithium ion battery diaphragm and a preparation method thereof.
Background
The trend of electric driving is becoming more and more intense, and countries encourage the use of high energy density batteries and have higher and higher requirements on the safety of the batteries. Lithium ion batteries are one of the important new energy sources at present due to high energy density and long cycle life, but in recent years, combustion or explosion accidents of electronic/power systems such as mobile phones and automobiles are frequent, and the lithium ion batteries bring convenience to people and are accompanied with danger risks. The separator, one of the four major materials of lithium batteries, is generally a polyolefin porous membrane, and mainly plays a role in separating the positive and negative electrodes, avoiding the short circuit of the battery and ensuring the Li during the charging and discharging process of lithium ions+The passing performance of the battery is ensured, and the smooth circuit in the battery is ensured. Since the melting point of the polyolefin-based porous film is generally lower than 200 ℃, when the battery is thermally runaway due to collision, overshoot, or the like, the separator may shrink or melt, causing direct contact between the positive electrode and the negative electrode, resulting in short circuit of the battery, and thus causing accidents such as ignition of the battery. Therefore, to meet the requirements of high power electronic devices or power/energy storage devices, improving the thermal stability of the separator has become a major development direction of lithium batteries.
The ceramic coating diaphragm has the advantages of reducing the thermal shrinkage of the diaphragm and improving the mechanical strength of the diaphragm due to higher heat resistance, thereby reducing the battery short circuit probability caused by the diaphragm shrinkage or melting caused by thermal runaway in the battery, lithium dendrite and the like puncturing the diaphragm. However, as the size of the battery increases and the demand for the lithium battery increases, the demand of the lithium battery cannot be met by a simple ceramic diaphragm, and the main problems of the lithium battery are as follows: (1) the ceramic diaphragm has no cohesiveness, is separated from an electrode plate in the process of putting the square battery into a shell, is not suitable for installation and the like; (2) the problems of wrinkling and the like easily occur in the process of manufacturing the pure ceramic diaphragm into the battery.
Disclosure of Invention
The invention provides a preparation method of a lithium ion battery diaphragm, a lithium ion battery and a preparation method of the lithium ion battery diaphragm, and aims to solve the technical problems that a ceramic diaphragm is not cohesive, is often separated from an electrode plate and is not suitable for installation, and wrinkles are easy to appear in the process of manufacturing the lithium ion battery.
The technical scheme adopted by the invention is as follows:
a preparation method of a lithium ion battery separator comprises the following steps:
(1) preparing a sizing agent with caking property;
(2) spraying the slurry obtained in the step (1) onto a rotating disc through a spraying device, throwing the slurry out of the rotating disc to flow through a regulating area to one side or two sides of a ceramic diaphragm so as to form a uniformly distributed slurry attaching area and a slurry non-attaching area, wherein the surface density of the slurry attached to the surface of the ceramic diaphragm is 0.2g/m2～1g/m2；
(3) And (3) coating and drying the ceramic diaphragm with the slurry in the step (2) to obtain the lithium ion battery diaphragm.
Further, the spraying amount of the slurry is adjusted by a spraying device; the spraying amount of the slurry is 500 ml/min-1500 ml/min.
Further, the rotating speed of the disc in the step (2) is 5000-15000 rpm.
Furthermore, the disks are 5-15 curved-surface disks.
Further, the adjusting area in the step (2) is provided with a first adjusting piece and a second adjusting piece for adjusting the slurry throwing-out path; the first adjusting member and the second adjusting member may be relatively moved according to the size of the ceramic diaphragm.
Further, the thickness of the slurry adhering to the surface of the ceramic separator is 2 to 6 μm.
Further, PVDF glue solution is adopted as the sizing agent in the step (1); the PVDF glue solution comprises: 7-15% of PVDF, 0.9-5% of binder, 0.04-1% of dispersant and the balance of water.
Further, the binder comprises one or more of polyacrylic acid (PAA), polyvinyl alcohol (PVA), Polyacrylonitrile (PAN) and carboxymethyl cellulose (CMC); the dispersant comprises one or more of polyoxyethylene dioleate, polytetraethylene glycol monostearate, polyvinylpyrrolidone and organic salt.
According to another aspect of the invention, the lithium ion battery comprises the lithium ion battery diaphragm obtained by the preparation method of the lithium ion battery diaphragm, the positive plate and the negative plate.
According to another aspect of the invention, the invention also provides a preparation method of the lithium ion battery, which comprises the steps of stacking the positive plate, the lithium ion battery diaphragm and the negative plate in sequence, then carrying out hot pressing treatment, and then winding the positive plate, the lithium ion battery diaphragm and the negative plate into a battery cell for carrying out shell entering treatment; the hot pressing treatment adopts 2000-3000 mpa pressure, 80-100 deg.c temperature and 30-90 s time.
The invention has the following beneficial effects:
according to the preparation method of the lithium ion battery diaphragm, the slurry is sprayed onto the rotating disc through the spraying device, the high-speed rotating disc uniformly disperses the slurry on the rotating disc into small droplets to be thrown to the surface of the ceramic diaphragm, and the slurry is locally adhered to one side or two sides of the ceramic diaphragm, so that the ceramic diaphragm has certain cohesiveness, and the adhesion degree of the ceramic diaphragm and a lithium battery pole piece is improved. And, because the thick liquids are attached to ceramic diaphragm surface for local homodisperse, therefore thick liquids attach to the district and form the bearing structure who has certain bearing capacity between ceramic diaphragm and lithium-ion battery pole piece, and thick liquids non-attach to the district and provide certain expansion space for lithium-ion battery pole inflation, and the expansion space dispersion is even, ceramic diaphragm and lithium-ion battery pole piece's bonding strength has been promoted, prevent that lithium-ion battery pole piece thermal expansion and ceramic diaphragm from taking place the staggered floor phenomenon, further improve the laminating degree of ceramic diaphragm and lithium-ion battery pole piece, effectively prevent the phenomenon of fold and interior short circuit that lithium-ion battery appears, thereby make lithium-ion battery's security performance obtain greatly improving. The preparation method of the lithium ion battery diaphragm has the advantages of simple process and strong operability, can complete the combination of the ceramic diaphragm and the slurry only by simple equipment such as a spraying device, a disc and the like, does not need expensive processing equipment, has low production cost, and is beneficial to continuous and large-scale production.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic view of interface flatness after disassembly of a battery according to preferred embodiment 1 of the present invention;
FIG. 2 is a schematic view showing the interface flatness after the disassembly of a battery according to preferred embodiment 2 of the present invention;
FIG. 3 is a schematic view showing the interface flatness after disassembly of a battery according to preferred embodiment 3 of the present invention;
FIG. 4 is a schematic view showing the interface flatness after the disassembly of a battery according to preferred embodiment 4 of the present invention;
FIG. 5 is a schematic illustration of the interface flatness of a disassembled cell of a preferred comparative example of the present invention; and
fig. 6 is a schematic view of an electron microscope of the lithium ion battery separator of preferred embodiment 4 of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
Fig. 1 is a schematic view of interface flatness after disassembly of a battery according to preferred embodiment 1 of the present invention; FIG. 2 is a schematic view showing the interface flatness after the disassembly of a battery according to preferred embodiment 2 of the present invention; FIG. 3 is a schematic view showing the interface flatness after disassembly of a battery according to preferred embodiment 3 of the present invention; FIG. 4 is a schematic view showing the interface flatness after the disassembly of a battery according to preferred embodiment 4 of the present invention; FIG. 5 is a schematic illustration of the interface flatness of a disassembled cell of a preferred comparative example of the present invention; fig. 6 is a schematic view of an electron microscope of the lithium ion battery separator of preferred embodiment 4 of the present invention.
The preparation method of the lithium ion battery separator comprises the following steps:
(1) preparing a sizing agent with caking property;
(2) spraying the slurry obtained in the step (1) onto a rotating disc through a spraying device, throwing the slurry out of the rotating disc to flow through a regulating area to one side or two sides of a ceramic diaphragm so as to form a uniformly distributed slurry attaching area and a slurry non-attaching area, wherein the surface density of the slurry attached to the surface of the ceramic diaphragm is 0.2g/m2～1g/m2；
(3) And (3) coating and drying the ceramic diaphragm with the slurry in the step (2) to obtain the lithium ion battery diaphragm.
According to the preparation method of the lithium ion battery diaphragm, the slurry is sprayed onto the rotating disc through the spraying device, the high-speed rotating disc uniformly disperses the slurry on the rotating disc into small droplets to be thrown to the surface of the ceramic diaphragm, and the slurry is locally adhered to one side or two sides of the ceramic diaphragm, so that the ceramic diaphragm has certain cohesiveness, and the adhesion degree of the ceramic diaphragm and a lithium battery pole piece is improved. And, because the thick liquids are attached to ceramic diaphragm surface for local homodisperse, therefore thick liquids attach to the district and form the bearing structure who has certain bearing capacity between ceramic diaphragm and lithium-ion battery pole piece, and thick liquids non-attach to the district and provide certain expansion space for lithium-ion battery pole piece inflation, and the expansion space dispersion is even, ceramic diaphragm and lithium-ion battery pole piece's bonding strength has been promoted, prevent that lithium-ion battery pole piece thermal expansion and ceramic diaphragm from taking place the staggered floor phenomenon, further improve the laminating degree of ceramic diaphragm and lithium-ion battery pole piece, effectively prevent the phenomenon of fold and interior short circuit that lithium-ion battery appears, thereby make lithium-ion battery's security performance obtain greatly improving. The preparation method of the lithium ion battery diaphragm has the advantages of simple process and strong operability, can complete the combination of the ceramic diaphragm and the slurry only by simple equipment such as a spraying device, a disc and the like, does not need expensive processing equipment, has low production cost, and is beneficial to continuous and large-scale production.
In this embodiment, the amount of the slurry sprayed is adjusted by the spraying device. The spraying amount of the slurry is 500 ml/min-1500 ml/min. The slurry is sprayed to the surface of the disc through the spraying device, the spraying amount of the slurry is adjusted to control the spraying amount to be 500 ml/min-1500 ml/min, so that the slurry is thrown out of the disc at a high speed based on the action of centrifugal force, and when the rotating speed of the disc is a determined value, the more the spraying amount of the slurry is, the larger the particle size of the slurry formed by throwing the slurry out of the disc at a high speed is. However, when the spraying amount exceeds 1500ml/min, the small slurry drops formed by throwing the excessive slurry out of the disc are not uniformly dispersed, the small slurry drops with overlarge or undersize granularity are formed and attached to the surface of the ceramic diaphragm, and when the ceramic diaphragm is attached to the lithium battery pole piece, part of the slurry cannot contact the lithium battery pole piece, so that the bonding strength of the ceramic diaphragm and the lithium battery pole piece is reduced.
In this embodiment, the rotation speed of the disk in the step (2) is 5000 to 15000 rpm. The slurry is firstly sprayed onto the disc through the spraying device and then thrown out of the disc to the surface of the ceramic diaphragm, so that the phenomenon of local omission or repeated adhesion on the surface of the ceramic diaphragm is effectively prevented. And when slurry droplets formed by throwing the disc flow through the adjusting area, the slurry droplets are in full contact with air, so that moisture in the slurry droplets is partially evaporated, the slurry droplets are adhered to the surface of the ceramic diaphragm and cannot flow down from the surface of the ceramic diaphragm, therefore, the rotating speed of the disc is adjusted to be 5000-15000 rpm, on one hand, the disc is cut by the centrifugal force of the disc to form uniformly dispersed slurry droplets, on the other hand, the size of the particle size of the slurry droplets is controlled by adjusting the rotating speed of the disc, and thus the ceramic diaphragm with different sizes and different requirements is met. In general, the faster the rotation speed of the disk, the smaller the size of the slurry droplets, and the smaller the thickness of the slurry formed on the surface of the ceramic separator, but when the slurry thickness is less than 2 μm, the adhesion between the ceramic separator and the lithium battery electrode sheet is lowered, and therefore, the rotation speed of the disk is 5000 to 15000 rpm.
In this embodiment, the disks are 5-15 curved disks. The disc is designed to be a curved disc, so that a storage cavity for temporarily containing the slurry is formed, and the situation that in the centrifugal force throwing process, part of slurry which is not thrown out slides out of the disc along with the disc, so that the waste of raw materials is caused, and the formation of other slurry small drops is influenced is prevented. Preferably, the center of the curved disc is provided with a central through hole, and the lower end of the central through hole is provided with a material collecting device for recovering slurry. The collecting device is provided with a pipeline communicated with the spraying device so as to spray the recovered slurry again, thereby reducing the waste of raw materials. The discs are 5-15 curved-surface discs, the diameter of each disc is about 10cm, the spraying area of each disc is 10-20 cm, the width of the ceramic diaphragm is 500-1300 mm, and a plurality of discs are needed to uniformly disperse small slurry drops on the surface of the ceramic diaphragm.
In this embodiment, the adjusting area in the step (2) is provided with a first adjusting member and a second adjusting member for adjusting the slurry throwing-out path. The first adjusting member and the second adjusting member may be relatively moved according to the size of the ceramic diaphragm. The conditioning zone is provided with a first conditioning member and a second conditioning member which form a flow path for small droplets of slurry thrown from the disc. The first regulating member and the second regulating member can move to regulate the space size of the flow path, so that the ceramic diaphragm is suitable for ceramic diaphragms with different sizes or shapes. The first adjusting piece and the second adjusting piece can be two rectangular plates which are symmetrically arranged to form equidistant paths. The first adjusting piece and the second adjusting piece can be an upper semi-cylinder and a lower semi-cylinder which are mutually matched and have two ends communicated, or an upper semi-cone and a lower semi-cone which are mutually matched, so that different circulation paths of space structures are formed, the requirements of different ceramic diaphragms are met, and the phenomenon of missing and adhering in a large area is avoided.
In this example, the thickness of the slurry adhering to the surface of the ceramic separator was 2 μm to 6 μm. In the process of manufacturing the battery, the slurry is maintained at about 1 mu m after the battery is hot-pressed, so that the bonding strength of the ceramic diaphragm and the lithium battery pole piece is ensured, an enough expansion space of the lithium battery pole piece is reserved between the ceramic diaphragm and the lithium battery pole piece, the expansion space of each unit can be filled up by the expanded lithium battery, and the gap between the ceramic diaphragm and the lithium battery pole piece is minimized, so that the interface resistance is reduced, and the hardness of the battery core is improved. When the thickness of the slurry attached to the surface of the ceramic diaphragm is larger than 6 micrometers, the finally formed slurry greatly exceeds 1 micrometer, so that the expansion space is larger, the whole expansion space cannot be filled with the expanded lithium battery, the gap between the ceramic diaphragm and the lithium battery pole piece is larger, and the service performance of the battery is influenced.
In this embodiment, the slurry in step (1) is PVDF glue solution. Polyvinylidene fluoride (PVDF) for short, wherein the PVDF glue solution comprises: 7-15% of PVDF, 0.9-5% of binder, 0.04-1% of dispersant and the balance of water. The PVDF glue solution comprises PVDF, a binder, a dispersing agent and water, wherein the water is used as a solvent to replace a conventional organic solvent, so that the volatilization pollution of the organic solvent to the environment is reduced, and the influence of the volatilized organic solvent on the charging and discharging process of the lithium ion battery is avoided. The specific preparation method of the PVDF glue solution comprises the following steps: and fully and uniformly mixing water and the dispersing agent, stirring for 10-20 min, adding the binder, stirring for 10-20 min, adding PVDF, and stirring for 30min to obtain the slurry. The solid content of the slurry is about 10%, so that the injection treatment of an injection device is facilitated, the solid content is high, the viscosity of the obtained slurry is high, and the slurry is not favorably uniformly dispersed into slurry droplets to influence the subsequent performance of the lithium ion battery in the process of throwing the disc out at a high speed.
In this embodiment, the binder includes one or more of polyacrylic acid (PAA), polyvinyl alcohol (PVA), Polyacrylonitrile (PAN), and carboxymethyl cellulose (CMC). The dispersant comprises one or more of polyoxyethylene dioleate, polytetraethylene glycol monostearate, polyvinylpyrrolidone and organic salt. In general, PVDF is generally soluble in organic solvents and not readily soluble directly in water, and thus is uniformly dispersed in water by adding a binder and a dispersant.
According to another aspect of the invention, the lithium ion battery comprises the lithium ion battery diaphragm obtained by the preparation method of the lithium ion battery diaphragm, the positive plate and the negative plate. According to the lithium ion battery diaphragm obtained by the preparation method of the lithium ion battery diaphragm, the lithium ion battery diaphragm improves the heat resistance of the diaphragm, improves the infiltration of electrolyte, improves the bonding strength of the diaphragm and positive and negative pole pieces, prevents internal short circuit between the diaphragm and electrodes due to staggered layers, improves the hardness of the battery, and greatly improves the safety performance of the battery.
According to another aspect of the invention, the invention also provides a preparation method of the lithium ion battery, which comprises the steps of stacking the positive plate, the lithium ion battery diaphragm and the negative plate in sequence, then carrying out hot pressing treatment, and then winding the positive plate, the lithium ion battery diaphragm and the negative plate into a battery cell for carrying out shell entering treatment; the hot pressing treatment adopts 2000-3000 mpa pressure, 80-100 deg.c temperature and 30-90 s time. The PVDF polymer material can be softened when being heated, is dissolved and generates cohesiveness, the original PVDF glue solution with the diameter of 2-6 microns can be pressed into the thickness of about 1 micron after being hot-pressed by a hot-pressing treatment process, the hot-pressing treatment process is confirmed by testing the thickness and the hardness of a battery core after hot-pressing, if the hot-pressing pressure is too low, a micelle formed after the hot-pressing treatment of the PVDF glue solution is larger than 1 micron, the battery core is too thick and needs to be adjusted in pressure, the hot-pressing temperature is too high, the treated battery core is softer, the PVDF glue solution does not exert the effect of the PVDF glue solution, the battery core is softer, the hot-pressing temperature and the hot-pressing time need to be adjusted, and therefore, the hot-pressing treatment process is finally confirmed to adopt the pressure of 2000-3000 mpa, the temperature of 80-100 ℃ and the hot-pressing.
Examples
Example 1
(1) Preparing PVDF glue solution with adhesive property, fully and uniformly mixing 44.38kg of water and 0.06kg of polyvinylpyrrolidone with the solid content of 40%, stirring for 15min, then adding 1.06kg of polyacrylic acid with the solid content of 45%, stirring for 15min, adding 4.5kg of PVDF, and stirring for 30min to obtain slurry, wherein the 0.06kg of polyvinylpyrrolidone with the solid content of 40%, the 0.06kg of dispersant contains 40% of polyvinylpyrrolidone, the solvent is water, the 1.06kg of polyacrylic acid with the solid content of 45% and the 1.06kg of binder contains 45% of polyacrylic acid;
(2) spraying the slurry obtained in the step (1) onto a rotating disc through a spraying device, wherein the spraying amount of the slurry is 800ml/min, the rotating speed of the disc is 7000rpm, 5 discs are horizontally and longitudinally arranged on the rotating disc at the moment, the slurry is thrown out of the disc and flows through an adjusting area, a first adjusting piece and a second adjusting piece in the adjusting area are symmetrically arranged to form an equidistant long path to reach one side of a ceramic diaphragm with the thickness of (12+4) mu m, then, the other side of the ceramic diaphragm is treated, and the surface density of the surface of the single-side ceramic diaphragm is controlled to be 0.2g/m2When the thickness of the ceramic diaphragm is (12+4+2+2) mu m;
(3) and (3) coating the ceramic diaphragm with the slurry in the step (2), and drying in an oven at the temperature of 55 ℃ to obtain the lithium ion battery diaphragm.
Example 2
(1) Preparing PVDF glue solution with cohesiveness, fully and uniformly mixing 43.76kg of water with 0.13kg of polyoxyethylene dioleate with the solid content of 40%, stirring for 15min, then adding 6.33kg of polyacrylonitrile with the solid content of 15%, stirring for 20min, adding 4kg of PVDF, and stirring for 30min to obtain slurry;
(2) spraying the slurry obtained in the step (1) onto a rotating disc through a spraying device, wherein the spraying amount of the slurry is 800ml/min, the rotating speed of the disc is 12000rpm, 6 discs are horizontally and longitudinally arranged on the rotating disc at the moment, the slurry is thrown out of the disc and flows through an adjusting area, a first adjusting piece and a second adjusting piece in the adjusting area are symmetrically arranged to form an equidistant long path to reach one side of a ceramic diaphragm with the thickness of (12+4) mu m, then, the other side of the ceramic diaphragm is treated, and the surface density of the surface of the single-side ceramic diaphragm is controlled to be 0.5g/m2When the thickness of the ceramic diaphragm is (12+4+3+3) mu m;
(3) and (3) coating the ceramic diaphragm with the slurry in the step (2), and drying in an oven at the temperature of 55 ℃ to obtain the lithium ion battery diaphragm.
Example 3
(1) Preparing PVDF glue solution with cohesiveness, fully and uniformly mixing 38.54kg of water with 0.38kg of polyvinylpyrrolidone with the solid content of 40%, stirring for 12min, then adding 7.33kg of polyacrylonitrile with the solid content of 15%, stirring for 18min, adding 3.75kg of PVDF, and stirring for 30min to obtain slurry;
(2) spraying the slurry obtained in the step (1) onto a rotating disc through a spraying device, wherein the spraying amount of the slurry is 1000ml/min, the rotating speed of the disc is 10000rpm, 6 discs are horizontally and longitudinally arranged on the rotating disc at the moment, the slurry is thrown out of the disc and flows through an adjusting area, a first adjusting piece and a second adjusting piece in the adjusting area are symmetrically arranged to form an equidistant long path to reach one side of a ceramic diaphragm with the thickness of (12+4) mu m, then, the other side of the ceramic diaphragm is treated, and the surface density of the surface of the single-side ceramic diaphragm is controlled to be 0.6g/m2When the thickness of the ceramic diaphragm is (12+4+5+5) mu m;
(3) and (3) coating the ceramic diaphragm with the slurry in the step (2), and drying in an oven at the temperature of 55 ℃ to obtain the lithium ion battery diaphragm.
Example 4
(1) Preparing PVDF glue solution with cohesiveness, fully and uniformly mixing 40.85kg of water with 0.15kg of polyvinylpyrrolidone with the solid content of 40%, stirring for 15min, then adding 3.6kg of polyacrylonitrile with the solid content of 15%, stirring for 15min, adding 5.4kg of PVDF, and stirring for 30min to obtain slurry;
(2) spraying the slurry obtained in the step (1) onto a rotating disc through a spraying device, wherein the spraying amount of the slurry is 1500ml/min, the rotating speed of the disc is 10000rpm, 8 discs are horizontally and longitudinally arranged on the rotating disc at the moment, the slurry is thrown out of the disc and flows through an adjusting area, a first adjusting piece and a second adjusting piece in the adjusting area are symmetrically arranged to form an equidistant long path to reach one side of a ceramic diaphragm with the thickness of (12+4) mu m, then, the other side of the ceramic diaphragm is treated, and the surface density of the surface of the single-side ceramic diaphragm is controlled to be 1g/m2When the thickness of the ceramic diaphragm is (12+4+6+6) mu m;
(3) and (3) coating the ceramic diaphragm with the slurry in the step (2), and drying in an oven at the temperature of 55 ℃ to obtain the lithium ion battery diaphragm.
Comparative example 1
A ceramic diaphragm of 12+4 thickness was used.
The lithium ion battery diaphragms of the embodiments 1 to 4 and the ceramic diaphragm of the comparative example 1 are respectively cut into a size of A4 paper, a group of two diaphragms are taken, the surfaces with the slurry of the embodiments 1 to 4 are opposite, the surfaces of the two ceramic diaphragms of the comparative example 1 are in contact with each other, the two diaphragms are clamped between two plastic sheets and pass through a plastic packaging machine, the temperature of the plastic packaging machine is set to be 100 ℃, then the diaphragms are cut into sample strips with the thickness of 25mm x 100mm, a universal stretching machine is used for testing the bonding strength, the test results are shown in Table 1, the lithium ion battery diaphragms of the embodiments 1 to 4 have the bonding property, the positive electrode and the negative electrode of the battery can be bonded together, and the battery can be conveniently placed into a shell after being wound into a battery core.
TABLE 1 determination of bonding strength between lithium ion battery separator and ceramic separator
The positive plate, the lithium ion battery diaphragm of the embodiment 1-4, the ceramic diaphragm of the comparative example 1 and the negative plate are wound, hot-pressed, placed into a shell, injected with liquid, sealed, formed, subjected to volume grading treatment, the battery is disassembled, and the flatness of the surface of the battery is observed, as shown in fig. 1, fig. 2, fig. 3, fig. 4 and fig. 5, the interface flatness of the disassembled battery of the embodiment 1-4 is better than that of the comparative example 1.
The lithium ion battery separator of the preferred embodiment 4 is subjected to electron microscope detection, and as shown in fig. 6, the PVDF glue solution is subjected to hot pressing to form micelles, and a space is formed between the micelles, so that after the battery is manufactured, a certain space is provided for expansion of the battery, and the battery is prevented from wrinkling and the like.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The preparation method of the lithium ion battery separator is characterized by comprising the following steps:
(1) preparing a sizing agent with caking property;
(2) spraying the slurry obtained in the step (1) onto a rotating disc through a spraying device, throwing the slurry out of the rotating disc to flow through a regulating area to one side or two sides of a ceramic diaphragm so as to form a uniformly distributed slurry attaching area and a slurry non-attaching area, wherein the surface density of the slurry attached to the surface of the ceramic diaphragm is 0.2g/m2～1g/m2；
(3) And (3) coating and drying the ceramic diaphragm with the slurry in the step (2) to obtain the lithium ion battery diaphragm.
2. The method for producing a lithium ion battery separator according to claim 1,
the spraying amount of the slurry is adjusted by a spraying device;
the spraying amount of the slurry is 500 ml/min-1500 ml/min.
3. The method for producing a lithium ion battery separator according to claim 1,
the rotating speed of the disc in the step (2) is 5000-15000 rpm.
4. The method for producing a lithium ion battery separator according to claim 3,
the disc is 5 ~ 15 curved surface discs.
5. The method for producing a lithium ion battery separator according to claim 1,
the adjusting area in the step (2) is provided with a first adjusting piece and a second adjusting piece for adjusting a slurry throwing-out path;
the first adjusting member and the second adjusting member may be relatively movable according to the size of the ceramic diaphragm.
6. The method for producing a lithium ion battery separator according to claim 1,
the thickness of the slurry attached to the surface of the ceramic diaphragm is 2-6 mu m.
7. The method for producing a lithium ion battery separator according to claim 1,
the slurry in the step (1) adopts PVDF glue solution;
the PVDF glue solution comprises: 7-15% of PVDF, 0.9-5% of binder, 0.04-1% of dispersant and the balance of water.
8. The method for producing a lithium ion battery separator according to claim 7,
the binder comprises one or more of polyacrylic acid (PAA), polyvinyl alcohol (PVA), Polyacrylonitrile (PAN) and carboxymethyl cellulose (CMC);
the dispersing agent comprises one or more of polyoxyethylene dioleate, polytetraethylene glycol monostearate, polyvinylpyrrolidone and organic salt.
9. A lithium ion battery comprising the lithium ion battery separator obtained by the method for producing a lithium ion battery separator according to any one of claims 1 to 8, a positive electrode sheet, and a negative electrode sheet.
10. The preparation method of the lithium ion battery of claim 9, characterized in that the positive plate, the lithium ion battery diaphragm and the negative plate are stacked in sequence, then are subjected to hot pressing treatment, and are wound into a battery cell to be subjected to shell entering treatment;
the hot pressing treatment adopts 2000-3000 mpa pressure, 80-100 ℃ temperature and 30-90 s time.
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Cited By (1)
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|---|---|---|---|---|
| WO2022122032A1 (en) * | 2020-12-10 | 2022-06-16 | 珠海冠宇电池股份有限公司 | Lithium battery |
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