CN111599971A - High-safety regular matrix coating adhesive lithium ion battery diaphragm and preparation method and application thereof - Google Patents
High-safety regular matrix coating adhesive lithium ion battery diaphragm and preparation method and application thereof Download PDFInfo
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- CN111599971A CN111599971A CN202010520552.0A CN202010520552A CN111599971A CN 111599971 A CN111599971 A CN 111599971A CN 202010520552 A CN202010520552 A CN 202010520552A CN 111599971 A CN111599971 A CN 111599971A
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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
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
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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
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/403—Manufacturing processes of separators, membranes or diaphragms
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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
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
- H01M50/461—Separators, membranes or diaphragms characterised by their combination with electrodes with adhesive layers between electrodes and 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
Abstract
The invention discloses a lithium ion battery diaphragm with high safety and regular matrix coating cohesiveness, and a preparation method and application thereof. The lithium ion battery diaphragm comprises a substrate and adhesive polymer coatings arranged on one side or two sides of the substrate, wherein the adhesive polymer coatings are formed by coating adhesive polymer slurry in a regular matrix form, and the adhesive polymer slurry in the adhesive polymer coatings is regularly dispersed and arranged in an aggregate form. The invention uses the regularly controllable micron-sized adhesive polymer aggregate to replace the nano-sized adhesive polymer powder adopted in the prior art, greatly reduces the influence of the traditional nano-sized adhesive polymer powder particles on the ventilation value of a multilayer compact structure, and simultaneously, the regular dot-shaped aggregate coating can be embedded into the pores on the surfaces of the positive and negative electrode materials when the battery cell is hot-pressed before being first placed into the shell to form stronger occlusion effect, so that the battery cell has good performance in the aspects of the cycle, the multiplying power, the safety and the like of the battery cell.
Description
Technical Field
The invention relates to the technical field of lithium ion battery diaphragms, in particular to a high-safety regular matrix coating adhesive lithium ion battery diaphragm and a preparation method and application thereof.
Background
Lithium ion batteries, also known as secondary batteries, are widely used as power sources for various mobile devices due to their high operating voltage, high energy density, no memory effect, and long cycle life. The lithium ion battery mainly comprises a positive electrode material, a negative electrode material, a diaphragm, electrolyte and a packaging material. The diaphragm is used as a barrier between the anode and the cathode, effectively isolates the anode and the cathode, and simultaneously provides a transmission channel for lithium ions in the charging and discharging process, and plays a vital role in the comprehensive performance of the lithium ion battery, so that the research on improving the safety, the usability and the manufacturability of the lithium ion battery by improving the performance of the diaphragm is more and more concerned.
In recent years, the energy density of lithium ion batteries is required to be higher and higher in China, in order to improve the energy density of the batteries, battery manufacturers are bound to select a ternary high-nickel positive electrode material, and a negative electrode material matched with the high-nickel positive electrode material can only be high-compacted graphite or a silicon-carbon negative electrode with a higher expansion coefficient at present. In the system, the battery core is easy to deform in the electrochemical reaction, meanwhile, the negative pole piece rebounds greatly and tends to increase gradually along with the continuous accumulation of the cycle number, and in order to solve the problem, the technical field in the industry provides a viscous diaphragm concept, aiming at effectively controlling the deformation of the battery core and inhibiting the rebounding of the negative pole piece by bonding the positive pole piece and the negative pole piece together under certain conditions, so that the capacity value of the energy density is improved to the maximum extent on the premise of not influencing the use of the battery.
In view of this, the invention is particularly proposed.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a high-safety regular matrix coating adhesive lithium ion battery separator, and a preparation method and application thereof.
The invention is realized by the following steps:
the embodiment of the invention provides a high-safety regular matrix coating adhesive lithium ion battery diaphragm which comprises a base material and adhesive polymer coatings arranged on one side or two sides of the base material, wherein the adhesive polymer coatings are formed by coating adhesive polymer slurry in a regular matrix form, and the adhesive polymer slurry in the adhesive polymer coatings is regularly distributed and arranged in an aggregate form.
The embodiment of the invention also provides a preparation method of the lithium ion battery diaphragm, which comprises the following steps: and coating the adhesive polymer slurry on one side or two sides of the base material to prepare the lithium ion battery diaphragm.
The embodiment of the invention provides a lithium ion battery, which comprises a positive electrode, a negative electrode, a diaphragm and the lithium ion battery diaphragm.
The invention has the following beneficial effects:
the invention provides a lithium ion battery diaphragm with high safety and regular matrix coating cohesiveness, and a preparation method and application thereof. The invention uses the regularly controllable micron-sized adhesive polymer aggregate to replace the nano-sized adhesive polymer powder adopted in the prior art, greatly reduces the influence of the traditional nano-sized adhesive polymer powder particles on the ventilation value of a multilayer compact structure, and simultaneously, the regular dot-shaped aggregate coating can be embedded into the pores on the surfaces of the positive and negative electrode materials when the battery cell is hot-pressed before being first placed into the shell to form stronger occlusion effect, so that the battery cell has good performance in the aspects of the cycle, the multiplying power, the safety and the like of the battery cell.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is an electron scanning image of the apparent morphology of the separator when the agglomerates of the cohesive polymer powder of the present invention are arranged in a regular pattern;
FIG. 2 is a comparison of the K value test for example 2 and comparative example 2 cells;
FIG. 3 is a comparison of the ACR value test for the cells of example 2 and comparative example 2;
FIG. 4 is a comparison of the DCR value test for the cells of example 2 and comparative example 2;
fig. 5 is a comparison of the hardness test for example 2 versus comparative example 2 cells.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
Aiming at the defects of the prior art, the invention provides the lithium ion battery diaphragm with high-safety regular matrix coating cohesiveness, which has good cohesiveness and ion conductivity and can effectively improve the safety performance and the cycle performance of the lithium ion battery.
The technical problem of the invention is solved by the following technical scheme:
in a first aspect, embodiments of the present invention provide a high-safety regular-matrix-coated adhesive lithium ion battery separator, including a substrate and an adhesive polymer coating disposed on one side or both sides of the substrate, where the adhesive polymer coating is formed by coating adhesive polymer slurry in a regular matrix form, and the adhesive polymer slurry in the adhesive polymer coating is regularly dispersed and arranged in an aggregate form.
The embodiment of the invention provides a lithium ion battery diaphragm which is a high-safety regular matrix coating adhesive lithium ion battery diaphragm, because the invention uses the regularly controllable micron-sized adhesive polymer aggregate to replace the nano-sized adhesive polymer powder adopted in the prior art, the influence of the traditional nano-sized adhesive polymer powder particles on the air permeability value of a multilayer compact packing structure is greatly reduced, meanwhile, the regular dot-shaped agglomerate coating can be embedded into the pores on the surfaces of the positive and negative electrode materials when the battery cell is hot-pressed before being placed into the shell for the first time to form stronger occlusion effect, the positive and negative pole pieces are further firmly stuck by swelling in the processes of clamp baking after liquid injection and the like, therefore, the adverse effects of pole piece bending and deformation on the cycle performance and thickness of the battery in the cycle process of the high-energy density battery cell are effectively prevented.
In an alternative embodiment, the substrate is a coating modified product of a microporous film made of polyolefin, aromatic polyamide or non-woven fabric;
preferably, the base material is obtained by coating high-temperature-resistant ceramic slurry on a polyolefin microporous membrane and then drying.
In an optional embodiment, the high-safety regular matrix is coated with a cohesive lithium ion battery separator, and the cohesive polymer slurry contains, by mass, 0.5 to 10% of an aqueous adhesive, 1 to 50% of a cohesive polymer, and the balance of water;
preferably, the aqueous adhesive comprises one or more of styrene-acrylic latex, styrene-butadiene rubber, polymethyl methacrylate, polybutyl methacrylate, polyethyl acrylate, polyvinyl alcohol, ethylene-vinyl acetate copolymer, polyvinyl acetate and polyurethane;
preferably, the adhesive polymer is powder, emulsion or mixture thereof, and the adhesive polymer comprises one or more of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile and polymethyl methacrylate;
in an optional embodiment, when the high-safety regular matrix is coated with the adhesive lithium ion battery separator, and the polymer slurry in the coating is regularly dispersed and arranged in an aggregate form, the height of the aggregate is controlled within the range of 0.5-10 μm, the diameter is controlled within the range of 80-500um, and the coverage area is controlled within the range of 1-50%;
in an optional embodiment, the high-safety regular matrix is coated with the adhesive lithium ion battery separator, and when the polymer powder particles or the emulsion and the mixture thereof in the coating are regularly dispersed and arranged in the form of aggregates, the aggregates are in a round shape with a convex whole, or in a triangle with a concave center and convex edges;
preferably, the circular aggregate is convex at the center and smooth at the edge, and the concave part at the center of the circular aggregate only contains a small amount of sparsely distributed cohesive polymer powder or emulsion and the mixture thereof;
further optimized, the rounded or triangular aggregate protrusions are rich in cohesive polymer powder particles and there are gaps between the particles rather than a close packed structure.
In a second aspect, embodiments of the present invention provide a method for preparing a high-safety regular matrix coating adhesive lithium ion battery separator as described above, comprising: and coating the adhesive polymer slurry on one side or two sides of the base material to prepare the lithium ion battery diaphragm.
In an alternative embodiment, the present invention provides a method for preparing the above-mentioned high-safety regular matrix-coated adhesive lithium ion battery separator, comprising the following steps:
a. uniformly stirring the aqueous adhesive and deionized water, adding adhesive polymer powder or emulsion and a mixture thereof, and uniformly dispersing to obtain a dispersion liquid;
b. grinding the dispersion liquid for 10-30min to obtain adhesive polymer slurry with viscosity of 5-1000mPa & s;
c. coating the slurry on one side or two sides of the coated modified film, and drying to obtain the high-safety regular matrix coated adhesive lithium ion battery diaphragm, wherein the drying temperature is 40-70 ℃;
in an alternative embodiment, the adhesive polymer syrup is regularly dispersed and arranged in the form of agglomerates using gravure coating, die coating, slot coating, or screen printing.
In a third aspect, an embodiment of the present invention provides a lithium ion battery, including a positive electrode, a negative electrode, a separator, and the lithium ion battery separator.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
a. Uniformly stirring 0.5kg of water-based styrene-butadiene rubber and 98.5kg of deionized water, adding a mixture of 1kg of polyvinylidene fluoride powder and emulsion, and uniformly dispersing to obtain a dispersion liquid;
b. grinding the dispersion liquid for 10min to obtain adhesive polymer slurry with viscosity of 5 mPas;
c. selecting a ceramic coating modified polyethylene microporous membrane with the thickness of 12 mu m as a base material, and coating the slurry on two sides of the base material by adopting a gravure coating mode at the coating speed of 50 m/min. Drying with five-stage oven at 40 deg.C, 55 deg.C, 60 deg.C, 55 deg.C and 50 deg.C to obtain adhesive polymer coating with thickness of 0.5 μm on both sides and increase of surface density of 0.2g/m2. The particle diameter of the mixture of polyvinylidene fluoride powder and emulsion in the coating is about 80um, and the coverage ratio is calculated to be about 30%.
Example 2
a. Uniformly stirring 3kg of aqueous polyvinyl acetate and 82kg of deionized water, adding 15kg of polyvinylidene fluoride-hexafluoropropylene copolymer powder, and uniformly dispersing to obtain a dispersion liquid;
b. grinding the dispersion liquid for 15min to obtain adhesive polymer slurry with the viscosity of 200mPa & s;
c. selecting a ceramic coating modified polyethylene microporous membrane with the thickness of 12 mu m as a base material, and coating the slurry on two sides of the base material in a screen coating mode at the coating speed of 50 m/min. Drying with five-stage oven at 40 deg.C, 55 deg.C, 65 deg.C, 55 deg.C and 50 deg.C to obtain adhesive polymer coating with thickness of 3 μm on both sides and surface density increase of 0.8g/m2. The particle diameter of polyvinylidene fluoride-hexafluoropropylene copolymer powder in the coating is about 300um, and the coverage ratio is calculated to be about 15%.
Example 3
a. Uniformly stirring 5kg of water-based polyethylacrylate and 70kg of deionized water, adding 25kg of polymethyl methacrylate homopolymer powder, and uniformly dispersing to obtain a dispersion liquid;
b. grinding the dispersion liquid for 20min to obtain adhesive polymer slurry with the viscosity of 400mPa & s;
c. selecting a ceramic coating modified polyethylene microporous membrane with the thickness of 12 mu m as a base material, and coating the slurry on two sides of the base material in an extrusion coating mode at the coating speed of 50 m/min. Drying with five-stage oven at 40 deg.C, 55 deg.C, 65 deg.C, 60 deg.C and 50 deg.C to obtain adhesive polymer coating with thickness of 5 μm on both sides and increase of surface density of 1.5g/m2. The particle size of polymethyl methacrylate homopolymer powder in the coating is about 200um, and the coverage ratio is calculated to be about 25%.
Example 4
a. After 8kg of water-based styrene-acrylic latex and 52kg of deionized water are uniformly stirred, 40kg of polyacrylonitrile powder is added, and dispersion liquid is obtained after uniform dispersion;
b. grinding the dispersion liquid for 25min to obtain adhesive polymer slurry with the viscosity of 700mPa & s;
c. the ceramic coating modified polyethylene microporous membrane with the thickness of 12 mu m is selected as a base material, the slurry is coated on two sides of the base material in a narrow-slit coating mode, and the coating speed is 50 m/min. Drying with five-stage oven at 50 deg.C, 55 deg.C, 65 deg.C, 60 deg.C and 55 deg.C respectively to obtain adhesive polymer coating with thickness of 8 μm on both sides and increase of surface density of 1.0g/m2. The particle size of polyacrylonitrile powder in the coating is about 500um, and the coverage ratio is calculated to be about 1%.
Example 5
a. Stirring 10kg of water-based polyethylacrylate and 40kg of deionized water uniformly, adding 50kg of polyvinylidene fluoride homopolymer powder, and dispersing uniformly to obtain a dispersion liquid;
b. grinding the dispersion liquid for 30min to obtain adhesive polymer slurry with the viscosity of 1000mPa & s;
c. selecting ceramic coating modified polyethylene microporous membrane with thickness of 12 mu mAs the base material, the slurry was applied to both sides of the base material by a screen coating method at a coating speed of 50 m/min. Drying with five-stage oven at 55 deg.C, 60 deg.C, 70 deg.C, 60 deg.C and 50 deg.C to obtain adhesive polymer coating with thickness of 10 μm on both sides and increase of surface density of 1.7g/m2. The particle size of polyvinylidene fluoride homopolymer powder in the coating is about 80um, and the coverage ratio is calculated to be about 50%.
Comparative example 1
The PVDF coating membrane prepared according to the conventional oily coating process is taken as a comparative example 1, the thickness of the membrane of the comparative example 1 is 12 microns, the thickness of a single-side coating layer and the thickness of an aluminum oxide coating layer are 3 microns, and the base membrane is a polyethylene microporous membrane.
Comparative example 2
The PVDF coating membrane prepared according to the conventional aqueous coating process is taken as a comparative example 2, the thickness of the membrane of the comparative example 2 is 16 microns, the single surface of the ceramic layer is 3 microns, the thickness of each of the two sides of the PVDF coating layer is 2 microns, the base membrane is a polyethylene microporous membrane, the thickness of the base membrane is 9 microns, the PVDF resin powder used in the comparative example 2 is spherical particles, and the particle size is 150-200 nm.
Test results
The diaphragms prepared in examples 1-5 and comparative examples 1-2 were subjected to surface density increase, air permeability and other related performance tests, and then laminated with the prepared nickel-cobalt-manganese ternary material (type 622) positive electrode sheet and graphite (FSN-1) negative electrode sheet, respectively, and subjected to hot dry pressing performance tests. The specific test conditions are that the steel is preheated for 10min at 75 ℃ and then hot pressed for 60s at 80 ℃ and 0.8 MPa. And (4) carrying out a comparison test of the bonding strength of the diaphragm and the pole piece after hot dry pressing is finished, and taking the stripped diaphragm to test the air permeability.
TABLE 1 test results
As can be seen from the data in table 1 above, the increase in areal density of the adhesive polymer coating in the separator of examples 1-5 of the invention is significantly less than that of comparative example 2, while maintaining the thermal shrinkage substantially unchanged. In addition, the ventilation increase value of the coating and the ventilation increase value after hot pressing are both obviously lower than those of a comparative example 2, which shows that the diaphragm prepared by the invention can greatly reduce the internal resistance of the diaphragm on the premise of maintaining the adhesive force, and improve the permeability of lithium ions, so that the multiplying power performance and the cycle performance of the battery are improved, and the problem of scrapping of the battery cell caused by the dead zone formed by the diaphragm micropores completely blocked by the adhesive material in the hot pressing process of the pole piece and the diaphragm is effectively avoided.
The separator prepared in the preferred embodiment 2 and the separator prepared in the comparative example 2 are respectively laminated with the prepared nickel-cobalt-manganese ternary material (622 type) positive pole piece and the prepared graphite (FSN-1) negative pole piece to prepare the soft package lithium ion battery. The internal resistance test of the two batteries is carried out under the condition of 3.85V, the capacity retention rate after 500 cycles under the condition of 1.0C constant-current constant-voltage charging/1.0C constant-current discharging, the cell expansion rate after 168 hours of standing under the conditions of 4.2V and 60 ℃, the K value, the ACR (acrylic resin reactor) value and the DCR (50% SOC) value are tested, and the obtained results are shown in a table 2.
TABLE 2 test results
As can be seen from the data in Table 2 above, the polymer lithium ion battery prepared by using the separator of the present invention is superior to the comparative separator in the aspects of cycle performance, self-discharge, increased internal resistance, cell hardness, etc.
Further, the lithium ion battery separator and performance provided in the above example 2 and comparative example 2 were compared and the test results are shown in fig. 1 to 5, and the following results are obtained:
FIG. 1: illustrating the morphology of the slurry in the claimed coating (example 2) as a regular matrix of dot-like polymer packed particles;
FIG. 2 is a drawing: the lithium ion batteries prepared in the examples of the invention (the lithium ion batteries prepared by the diaphragm of the example 2) have higher self-discharge performance than the conventional batteries (the lithium ion batteries prepared by the diaphragm of the comparative example 2);
figures 3-4: the lithium ion battery prepared by the method provided by the embodiment of the invention (the lithium ion battery prepared by the diaphragm of the embodiment 2) has the internal resistance change similar to or even superior to that of the conventional battery (the lithium ion battery prepared by the diaphragm of the comparative example 2) in the circulation process, and does not influence the battery performance;
FIG. 5: it is shown that the hardness of the battery prepared by the method provided by the embodiment of the invention (the lithium ion battery prepared by the diaphragm of the embodiment 2) is much higher than that of the battery prepared by the common method (the lithium ion battery prepared by the diaphragm of the comparative example 2), so that the battery can reduce the battery fault layer and short circuit caused by vibration and bumping in practical application. Thereby improving the safety of the battery.
To sum up, the embodiment of the invention provides a high-safety regular matrix coated adhesive lithium ion battery separator and a preparation method and application thereof, wherein the separator consists of a substrate and an adhesive polymer coating coated on one side or two sides of the substrate, the substrate is obtained by coating high-temperature resistant ceramic slurry on a polyolefin separator and then drying, and the coating is obtained by coating and drying the adhesive polymer slurry. The height, the diameter and the coverage area of the cohesive polymer aggregate can be flexibly changed by adjusting the coating process, meanwhile, the cohesive coating not only improves the adhesive force between the diaphragm and the positive and negative pole pieces, but also provides sufficient expansion space for the rocking chair type charging and discharging process of the battery, thereby improving the safety performance, the cycle performance and the rate capability of the battery.
Compared with the prior art, the lithium ion battery diaphragm coated with the high-safety regular matrix and having the adhesive property has the following advantages:
the invention adopts a special printing process to coat PVDF, the size, the spacing, the thickness and the appearance of the regularly arranged PVDF aggregates in the prepared coating are controllable, the PVDF aggregates can be completely customized according to the requirement of a customer on the coverage rate of the coating, and simultaneously, the utilization rate of slurry is very high due to the controllability of the coating, so that the PVDF coating has obvious cost advantage compared with the traditional roller coating and spraying.
The invention uses the regularly controllable micron-sized adhesive polymer aggregate to replace the nano-sized adhesive polymer powder adopted in the prior art, greatly reduces the influence of the traditional nano-sized adhesive polymer powder particles on the ventilation value of a multilayer compact stacking structure, simultaneously, the regular dot-shaped aggregate coating can be embedded into the pores on the surfaces of the positive and negative electrode materials during hot pressing before the battery cell is firstly placed into the shell to form stronger occlusion effect, and the positive and negative electrode plates are further firmly adhered through swelling in the processes of clamp baking and the like after liquid injection, thereby effectively preventing the adverse effects of the bending and deformation of the electrode plates in the circulation process of the high-energy density battery cell on the cycle performance and thickness of the battery.
The cohesive polymer material used in the invention has low swelling rate, small proportion of copolymer, high modulus and good liquid absorption and retention capability. The battery has good performance in the aspects of circulation, multiplying power, safety and the like of the battery core. Meanwhile, the cohesive polymer aggregate in the coating prepared by the invention is an effective cohesive point, so that the use of raw materials can be reduced, and the adhesive effect of the coating can be exerted to the greatest extent. In addition, a naked base film or a ceramic film is arranged between the polymer aggregates, so that a smoother transmission channel can be effectively provided for lithium ions, and meanwhile, sufficient expansion space can be provided for positive and negative pole pieces in a high-energy-density lithium ion battery in the charging and discharging process.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to 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 high-safety regular matrix coating adhesive lithium ion battery separator is characterized by comprising a substrate and adhesive polymer coatings arranged on one side or two sides of the substrate, wherein the adhesive polymer coatings are formed by coating adhesive polymer slurry in a regular matrix form, and the adhesive polymer slurry in the adhesive polymer coatings is regularly and dispersedly distributed in an aggregate form.
2. The lithium ion battery separator according to claim 1, wherein the substrate is a coating modified product of a microporous film made of polyolefin, aromatic polyamide or non-woven fabric;
preferably, the base material is obtained by coating high-temperature-resistant ceramic slurry on the polyolefin microporous membrane and then drying.
3. The lithium ion battery separator according to claim 1, wherein the adhesive polymer slurry comprises, by mass, 0.5 to 10% of an aqueous adhesive, 1 to 50% of an adhesive polymer, and the balance of water;
preferably, the aqueous adhesive comprises one or more of styrene-acrylic latex, styrene-butadiene rubber, polymethyl methacrylate, polybutyl methacrylate, polyethyl acrylate, polyvinyl alcohol, ethylene-vinyl acetate copolymer, polyvinyl acetate and polyurethane;
preferably, the adhesive polymer is powder, emulsion or mixture thereof, and the adhesive polymer comprises one or more of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile and polymethyl methacrylate.
4. The lithium ion battery separator as claimed in claim 3, wherein the adhesive polymer in the adhesive polymer coating layer is in the form of agglomerates, and when the adhesive polymer is regularly dispersed and arranged, the height of the agglomerates is controlled to be 0.5-10 μm, the diameter is controlled to be 80-500 μm, and the coverage area is controlled to be 1-50%.
5. The lithium ion battery separator according to claim 1, wherein the agglomerates are in the shape of an overall convex circle, or a triangle with a concave center and convex edges;
preferably, the circular aggregate is convex at the center and smooth at the edge, and the concave part at the center of the circular aggregate contains a small amount of sparsely distributed cohesive polymer powder, emulsion or mixture thereof;
more preferably, the rounded or triangular aggregate protrusions are rich in cohesive polymer powder particles with interstices between the particles rather than a close-packed structure.
6. The method for preparing a high-safety regular matrix coated adhesive lithium ion battery separator according to any one of claims 1 to 5, wherein the adhesive polymer paste is coated on one side or both sides of the substrate.
7. The method for preparing the lithium ion battery separator according to claim 6, wherein the preparation of the adhesive polymer paste comprises the steps of:
grinding the dispersion liquid of the adhesive polymer slurry for 10-30min to obtain adhesive polymer slurry with viscosity of 5-1000mPa & s;
preferably, the preparation steps of the dispersion are as follows: and uniformly stirring the aqueous adhesive and deionized water, mixing the aqueous adhesive and the deionized water with the adhesive polymer, and uniformly dispersing to obtain a dispersion.
8. The method for preparing a lithium ion battery separator according to claim 6, wherein the adhesive polymer paste is regularly dispersed in the form of agglomerates by gravure coating, die coating, slot coating, or screen printing coating.
9. The method for preparing a lithium ion battery separator according to any one of claims 6 to 8, further comprising: drying the substrate coated with the adhesive polymer slurry;
preferably, the drying temperature is 40-70 ℃.
10. A lithium ion battery, which is characterized by comprising a positive electrode, a negative electrode, a separator and the lithium ion battery separator as defined in any one of claims 1 to 5 or the lithium ion battery separator prepared by the preparation method as defined in any one of claims 6 to 9.
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| CN202010520552.0A CN111599971A (en) | 2020-06-08 | 2020-06-08 | High-safety regular matrix coating adhesive lithium ion battery diaphragm and preparation method and application thereof |
| CN202211271969.3A CN115411457A (en) | 2020-06-08 | 2020-06-08 | Lithium ion battery diaphragm and preparation method and application thereof |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113563768A (en) * | 2021-07-15 | 2021-10-29 | 欣旺达电动汽车电池有限公司 | Adhesive coating slurry, separator and lithium ion battery |
| CN113823877A (en) * | 2021-08-31 | 2021-12-21 | 远景动力技术(江苏)有限公司 | Diaphragm of lithium ion battery and preparation method and application thereof |
| WO2022110225A1 (en) * | 2020-11-30 | 2022-06-02 | 宁德时代新能源科技股份有限公司 | Isolation membrane, secondary battery comprising same, and related battery module, battery pack and device |
| CN114976492A (en) * | 2022-05-05 | 2022-08-30 | 广东卓高新材料科技有限公司 | High-cohesiveness polymer composite coating diaphragm and preparation method thereof |
| CN115207566A (en) * | 2022-08-24 | 2022-10-18 | 宁德卓高新材料科技有限公司 | PMMA/PVDF composite diaphragm and preparation method and application thereof |
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| WO2022110225A1 (en) * | 2020-11-30 | 2022-06-02 | 宁德时代新能源科技股份有限公司 | Isolation membrane, secondary battery comprising same, and related battery module, battery pack and device |
| CN113563768A (en) * | 2021-07-15 | 2021-10-29 | 欣旺达电动汽车电池有限公司 | Adhesive coating slurry, separator and lithium ion battery |
| CN113823877A (en) * | 2021-08-31 | 2021-12-21 | 远景动力技术(江苏)有限公司 | Diaphragm of lithium ion battery and preparation method and application thereof |
| CN114976492A (en) * | 2022-05-05 | 2022-08-30 | 广东卓高新材料科技有限公司 | High-cohesiveness polymer composite coating diaphragm and preparation method thereof |
| CN114976492B (en) * | 2022-05-05 | 2023-10-20 | 广东卓高新材料科技有限公司 | High-cohesiveness polymer composite coating diaphragm and preparation method thereof |
| CN115207566A (en) * | 2022-08-24 | 2022-10-18 | 宁德卓高新材料科技有限公司 | PMMA/PVDF composite diaphragm and preparation method and application thereof |
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Application publication date: 20200828 |