CN115207571A - Lithium ion battery composite diaphragm and preparation method thereof - Google Patents

Lithium ion battery composite diaphragm and preparation method thereof Download PDF

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CN115207571A
CN115207571A CN202210755115.6A CN202210755115A CN115207571A CN 115207571 A CN115207571 A CN 115207571A CN 202210755115 A CN202210755115 A CN 202210755115A CN 115207571 A CN115207571 A CN 115207571A
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lithium ion
ion battery
polymer
viscosity
heat
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徐立洋
陈萌
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Gotion High Tech Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • 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
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • 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
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • 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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Abstract

The invention discloses a lithium ion battery composite diaphragm and a preparation method thereof, wherein the composite diaphragm comprises a base film, a high-viscosity high-molecular polymer and a high-heat-resistant polymer, wherein the high-viscosity high-molecular polymer and the high-heat-resistant polymer form a coating to be coated on the surface of the base film, molecular chains of the high-viscosity high-molecular polymer and the high-heat-resistant polymer are mutually wound, and meanwhile, the high-viscosity high-molecular polymer is crosslinked to form a net structure with pore channels on the surface; the preparation method comprises the following steps: dissolving high-viscosity high-molecular polymer and high-heat-resistance polymer in an organic solvent, adding a pore-forming agent to prepare a coating solution, coating the coating solution on the surface of a base membrane, placing the base membrane in a coagulating bath containing a cross-linking agent, performing coagulation pore-forming, extracting in water, and finally drying to obtain the composite diaphragm. The composite diaphragm provided by the invention has the advantages of high heat resistance, high toughness and high cohesiveness, and simultaneously inhibits the high swelling phenomenon caused by the high cohesiveness, and improves the safety performance of the lithium ion battery and the cycle performance of the battery.

Description

Lithium ion battery composite diaphragm and preparation method thereof
Technical Field
The invention relates to the technical field of lithium ion diaphragm coating, in particular to a lithium ion battery coating diaphragm with high heat resistance and strong adhesion and a preparation method thereof.
Background
In the lithium ion battery, the diaphragm is one of four main materials, and the main function of the diaphragm is to realize the transportation and conduction of lithium ions in the battery; and meanwhile, the electronic conduction is isolated, so that the short circuit caused by the short circuit of the anode and the cathode of the battery is prevented. The performance of the diaphragm not only determines the interfacial structure, internal resistance, capacity, circulation and other electrical properties of the battery, but also plays a vital role in the safety performance of the battery. The battery is different in kind and the separator used is different. In the lithium battery system, since the electrolyte is an organic solvent system, a separator material resistant to an organic solvent is required, and a polyolefin porous film having a high strength and a thin film is generally used. The lithium ion battery diaphragm has a complex structure, is pulled to drive the whole body, and has the following main technical parameters: thickness, porosity, air permeability, thermal shrinkage, tensile strength, puncture strength, elongation, pore size and distribution, closed cell rupture temperature, contact angle and the like.
The lithium ion battery diaphragm is formed by stretching a high molecular polymer, the mechanical strength-tensile strength performance of the diaphragm is realized in the stretching process, and meanwhile, the diaphragm inevitably has a thermal contraction phenomenon in the stretching direction. Due to the characteristics, the battery is easy to cause short circuit and further cause thermal runaway under high temperature because of shrinkage; on the other hand, the mechanical properties of the conventional PE and PP separators are sharply reduced at high temperature, so that the mechanical strength of the conventional PE and PP separators is insufficient to support normal operation in the battery, and the battery fails. In order to make the interface between the diaphragm and the pole piece more fit and improve the cycle performance, the traditional method is to coat a layer of high-viscosity high polymer on the basis of PP and PE base films, but the high-viscosity high polymer has great swelling, so that the cycle of the composite diaphragm applied to the lithium ion battery is sharply reduced.
In order to solve the problems, the preparation method of the high-heat-resistance and high-adhesion coating diaphragm and the application of the high-heat-resistance and high-adhesion coating diaphragm in the lithium ion battery ensure that the prepared diaphragm still has good mechanical properties at high temperature, namely high heat resistance and high toughness; meanwhile, the problem of inherent high swelling of the gluing diaphragm is solved while the gluing diaphragm has high viscosity.
Through retrieval, the chinese patent application No. 202011220686.7 discloses a lithium ion battery diaphragm, a preparation method and a lithium ion battery in 29/1/2021, wherein the lithium ion battery diaphragm comprises a porous base membrane, a high temperature resistant polymer and a polyvinylidene fluoride copolymer, and the high temperature resistant polymer and the polyvinylidene fluoride copolymer are injected into pores of the porous base membrane. However, the slurry made by the diaphragm is injected into the base film hole, and the defects of the method are that the porosity of the base film is reduced, and further the porosity of the composite diaphragm is reduced, and the polyvinylidene fluoride copolymer used by the method is a polyvinylidene fluoride and hexafluoropropylene copolymer which cannot play a role in bonding in the base film hole.
For another example, chinese patent application No. 201811055988.6, in 2019, 1 month and 11 days, discloses an oily coating and nano ceramic fiber composite membrane and a preparation method thereof, wherein the composite membrane is composed of the following components: the composite material comprises a high molecular polymer material, nano ceramic fibers, a binder, a dispersant, a pore-forming agent and an organic solvent, wherein the mass ratio of the components is as follows: 1-20 parts of high polymer material, 2-40 parts of nano ceramic fiber, 1.5-8 parts of binder, 0.05-1.5 parts of dispersant, 0.05-5 parts of pore-forming agent and 60-95 parts of organic solvent. The composite diaphragm slurry mainly comprises polyvinylidene fluoride and nano ceramic fibers, wherein the polyvinylidene fluoride can be dissolved in an organic solvent, the nano ceramic fibers are not dissolved in the organic solvent and only are dispersed, and the composite diaphragm can be pulverized and broken when being touched due to the fact that no continuous structure exists at high temperature.
Therefore, there is a need for a separator having both high heat resistance and strong adhesion, and a method for preparing the same.
Disclosure of Invention
1. Problems to be solved
Aiming at the problems of large swelling and no high temperature resistance of the existing lithium ion battery diaphragm, the invention provides a lithium ion battery composite diaphragm which has the advantages of high diaphragm breaking temperature, high adhesion, low swelling and the like.
The invention also provides a preparation method of the lithium ion battery composite diaphragm, and the composite coating diaphragm obtained by adapting the material components can still keep higher strength under the high-temperature condition, cannot be melted, molten and dripped, pulverized and the like, has high viscosity and avoids the defect of high swelling.
2. Technical scheme
In order to solve the problems, the technical scheme adopted by the invention is as follows:
a lithium ion battery composite diaphragm comprises a base film, a high-viscosity high-molecular polymer and a high-heat-resistant polymer, wherein the high-viscosity high-molecular polymer and the high-heat-resistant polymer form a coating to be coated on the surface of the base film, molecular chains of the high-viscosity high-molecular polymer and the high-heat-resistant polymer are mutually wound, and the high-viscosity high-molecular polymer is crosslinked to form a space network structure with pore channels on the surface. The thickness of the coating formed by the high-viscosity high-molecular polymer and the high-heat-resistant polymer is 1-5 mu m, and the porosity is 70%; the physical and chemical properties of the composite diaphragm are as follows: higher porosity is more than 50%, higher breakdown voltage is more than 1.5KV, and higher film breaking temperature is more than 250 ℃.
Furthermore, the base film is a PP/PE/PP three-layer co-extrusion base film, a PP1/PP2/PP1 three-layer co-extrusion base film, PP, PE, PET or PI, and the porosity is 40-50%.
Further, the high-viscosity polymer includes, but is not limited to, polyacrylate high-viscosity agents, which are not generally used as membrane materials because of their swelling, so the present invention takes polyacrylate high-viscosity agents as an example, and it can be stated that other high-viscosity agents (such as PVDF) having lower swelling than polyacrylate high-viscosity agents can also be applied to the composite membrane of the present invention.
Further, the polyacrylate type high viscosity agent includes, but is not limited to, polymethyl methacrylate, or a copolymer of two or more of methyl methacrylate, methacrylic acid, ethacrylic acid, ethyl methacrylate, and butyl methacrylate.
Further, the high heat-resistant polymer includes, but is not limited to, high molecular polymers shown below:
Figure BDA0003722203830000021
Figure BDA0003722203830000031
firstly, dissolving a high-viscosity high-molecular polymer and a high-heat-resistant polymer in an organic solvent, assisting with a pore-forming agent to prepare a coating solution, then coating the coating solution on the surface of a base film, placing the base film in a coagulating bath containing a cross-linking agent, forming pores through coagulation, then extracting the pore-forming agent from water, and finally drying to obtain the composite diaphragm. The mass fraction of the coating liquid is 2-80wt%.
Further, the mass ratio of the high-viscosity high-molecular polymer to the high-heat-resistant polymer is 5 to 0.1. The mass ratio of the pore-forming agent content to the coating material (the sum of the high-viscosity high-molecular polymer, the high-heat-resistant polymer and the organic solvent) is (0.1-0.5): 1.
Further, the organic solvent is NMP, DMAC or acetone, and the selection of the organic solvent requires that both the high-viscosity high-molecular polymer and the high-heat-resistant polymer are soluble in the solvent.
Further, the pore-forming agent is one or a mixture of more than one of polyethylene glycol, terpineol, amine carbonate, ammonium bicarbonate and ammonium oxalate, and the pore-forming agent plays a role in occupying sites to form pores.
Furthermore, the mass ratio of water to NMP in the coagulating bath is (1-9): 10, and the cross-linking agent accounts for 0.1-20wt% of the sum of the mass of water and NMP.
Further, the crosslinking agent is ethylene glycol dimethacrylate, divinylbenzene, diisocyanate or N, N-Methylenebisacrylamide (MBA).
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) The composite diaphragm has the advantages of high diaphragm breaking temperature, high cohesiveness, low swelling and the like; compared with the traditional diaphragm, the composite coating diaphragm can still maintain higher strength under the high-temperature condition, and can not melt, melt and drop, pulverize and the like; molecular chains of the high-viscosity high-molecular polymer and the high-heat-resistance polymer are wound and combined when the high-viscosity high-molecular polymer and the high-heat-resistance polymer are dissolved in the same solvent, and the high-viscosity high-molecular polymer is crosslinked under the action of a crosslinking agent, so that the appearance of a pore channel is controlled, the high-viscosity high-molecular polymer has high viscosity, and the defect of high swelling is avoided;
(2) In the preparation method of the composite diaphragm, the main materials of the prepared coating liquid are that the high heat-resistant polymer and the polyacrylate high-adhesive are both dissolved in the organic solvent and uniformly coated on the surface of the base film, so that the porosity of the composite diaphragm can be further improved, and the polyacrylate high-adhesive ensures that the composite diaphragm and a battery pole piece have good cohesiveness on the surface; wherein:
the polyacrylate high-viscosity agent provides a binding power between the composite diaphragm and the pole piece, is different from the prior art which uses polyvinylidene fluoride and hexafluoropropylene copolymer as a binding agent, is not a binding agent with the polyacrylate high-viscosity agent used in the invention, can provide stronger binding performance, but the super high swelling property of the polyacrylate high-viscosity agent can absorb electrolyte in a lithium ion battery, so the polyacrylate high-viscosity agent cannot be used for gluing the glue layer part in the diaphragm;
the aramid fiber material selected by the high heat-resistant polymer has good heat resistance at high temperature, and has a continuous network structure, so that the composite diaphragm is not pulverized at high temperature (200 ℃);
(3) In the preparation method of the composite diaphragm, in order to enable the pore structure of the coating to have a more uniform net-shaped structure and lower swelling performance, a cross-linking agent is additionally added during coagulation bath to cross-link polyacrylate high-viscosity agents, so that the obtained coating is more uniform and stable in appearance, the pore appearance of the coating is controlled, and aramid fiber swelling is inhibited;
(4) The composite diaphragm coating is of a continuous net structure, and is different from the structure in the prior art, the structure in the prior art is mostly simple accumulation of short fibers, so that the composite diaphragm can be pulverized at high temperature and can be broken when being touched;
(5) The base film used in the invention has a porosity of 40-50%, and has strong mechanical strength after being stretched at a high magnification.
Drawings
FIG. 1 is a SEM diagram of a composite separator prepared in example 1;
FIG. 2 is a cross-sectional cut SEM of the composite separator made in example 1;
fig. 3 is a SEM schematic of the composite separator prepared in comparative example 3;
fig. 4 is a pore size distribution diagram of the composite separator prepared in example 1 and comparative example 3.
Detailed Description
In order to make the technical means and the achievement effect of the invention easy to understand, the technical scheme of the invention is explained in detail through the specific embodiments.
Example 1
Adding an NMP solvent into meta-aramid stock solution and polymethyl methacrylate (PMMA), uniformly stirring, and adding a PEG pore-forming agent for mixing to ensure that the mass fraction of the meta-aramid: PMMA: PEG =1:1:1. the solid content of the mixed solution reaches 20% by blending proportion, and the mixed slurry is uniformly dispersed by mechanically stirring for 2 hours. Uniformly coating the mixed slurry on one side of a 9-micron base film in a micro-gravure coating mode, controlling the coating thickness to be about 3 microns, immersing the coated diaphragm into a coagulating bath formed by mixing 80wt% of NMP containing 0.2wt% of ethylene glycol dimethacrylate cross-linking agent and water, coagulating and forming holes, taking out after 1h, immersing the coagulated diaphragm into water, extracting for 1h at 30 ℃, extracting out a pore-forming agent, and finally drying residual moisture of the extracted diaphragm at 60 ℃ to obtain the composite coated diaphragm. The result was designated as example 1. FIG. 1 is a SEM illustration of the plane of the composite membrane prepared in this example; fig. 2 is a sectional cut SEM of the composite separator manufactured in this example.
Example 2
Adding an NMP solvent into meta-aramid stock solution and polymethyl methacrylate (PMMA), uniformly stirring, and adding a PEG pore-forming agent for mixing to ensure that the mass fraction of the meta-aramid: PMMA: PEG =2:4:3. the solid content of the mixed solution reaches 20% by blending proportion, and the mixed slurry is uniformly dispersed by mechanically stirring for 2 hours. Uniformly coating the mixed slurry on one side of a 9-micron base film in a micro-gravure coating mode, controlling the coating thickness to be about 3 microns, immersing the coated diaphragm into a coagulating bath formed by mixing 80wt% of NMP containing 0.2wt% of ethylene glycol dimethacrylate cross-linking agent and water, coagulating for 1h, taking out, immersing the coagulated diaphragm into water, extracting for 1h at 30 ℃, and finally drying the extracted diaphragm at 60 ℃ to obtain the composite coated diaphragm. The result was designated as example 2.
Example 3
Adding an NMP solvent into meta-aramid stock solution and polymethyl methacrylate (PMMA), uniformly stirring, and adding a PEG pore-forming agent for mixing to ensure that the mass fraction of the meta-aramid: PMMA: PEG =4:2:3. the solid content of the mixed solution reaches 20% by blending proportion, and the mixed slurry is uniformly dispersed by mechanically stirring for 2 hours. Uniformly coating the mixed slurry on one side of a 9-micron base film in a micro-gravure coating mode, controlling the coating thickness to be about 3 microns, immersing the coated diaphragm into a coagulating bath formed by mixing 80wt% of NMP containing 0.2wt% of ethylene glycol dimethacrylate cross-linking agent and water, coagulating for 1h, taking out, immersing the coagulated diaphragm into water, extracting for 1h at 30 ℃, and finally drying the extracted diaphragm at 60 ℃ to obtain the composite coated diaphragm. As example 3.
Comparative example 1
Adding an NMP solvent into the meta-aramid stock solution, uniformly stirring, and adding a PEG pore-forming agent for mixing to obtain the meta-aramid: PEG =2:1. the solid content of the mixed solution reaches 20% by blending proportion, and the mixed slurry is uniformly dispersed by mechanically stirring for 2 hours. Uniformly coating the mixed slurry on one side of a 9-micron base film in a micro-gravure coating mode, controlling the coating thickness to be about 3 microns, immersing the coated diaphragm into a coagulating bath formed by mixing 80wt% of NMP (N-methyl pyrrolidone) containing 0.2wt% of ethylene glycol dimethacrylate cross-linking agent with water, coagulating for 1h, taking out, immersing the coagulated diaphragm into water, extracting for 1h at 30 ℃, and finally drying the extracted diaphragm at 60 ℃ to obtain the meta-aramid coated diaphragm. Denoted as comparative 1.
Comparative example 2
Adding PMMA into an NMP solvent, stirring uniformly, adding a PEG pore-forming agent, and mixing to obtain a mixture with the mass fraction of PMMA: PEG =2:1. the solid content of the mixed solution reaches 20% by blending proportion, and the mixed slurry is uniformly dispersed by mechanically stirring for 2 hours. Uniformly coating the mixed slurry on one side of a 9-micron base film in a micro-gravure coating mode, controlling the coating thickness to be about 3 microns, immersing the coated diaphragm into a coagulating bath formed by mixing 80wt% of NMP (N-methyl pyrrolidone) containing 0.2wt% of ethylene glycol dimethacrylate cross-linking agent and water for coagulating for 1 hour, taking out, immersing the coagulated diaphragm into water for extracting for 1 hour at 30 ℃, and finally drying the extracted diaphragm at 60 ℃ to obtain the meta-aramid coated diaphragm. Denoted as comparative sample 2.
Comparative example 3
Adding an NMP solvent into meta-aramid stock solution and polymethyl methacrylate (PMMA), uniformly stirring, and adding a PEG pore-forming agent for mixing to ensure that the mass fraction of the meta-aramid: PMMA: PEG =1:1:1. the mixing proportion enables the solid content of the mixed solution to reach 20%, and the mixed slurry is uniformly dispersed by mechanical stirring for 2 hours. Uniformly coating the mixed slurry on one side of a 9-micron base film in a micro-gravure coating mode, controlling the coating thickness to be about 3 microns, immersing the coated diaphragm into a coagulating bath formed by mixing 80wt% NMP and water for coagulating for 1h, taking out, immersing the coagulated diaphragm into water for extracting for 1h at 30 ℃, and finally drying the extracted diaphragm at 60 ℃ to obtain the composite coated diaphragm. Denoted as comparative example 3. Fig. 3 is a SEM schematic of the plane of the composite separator prepared in this comparative example.
Performance testing
(1) The composite separators prepared in examples 1, 2 and 3 and comparative examples 1, 2 and 3 were subjected to a swelling test, which specifically includes: the diaphragm is immersed in national standard electrolyte for 10 days, the mass of the diaphragm before and after the test, the swelling ratio = mass after immersion/mass before immersion 100, and the test data are shown in table 1. It can be seen from comparative examples 1 and 2 that the swelling performance of the single aramid or PMMA coated membrane is very great, while the swelling performance of the reversed examples 1, 2, 3 is greatly reduced due to the entanglement of the two molecular chains.
(2) The samples 1 to 3 obtained in examples 1, 2 and 3 and the comparative samples 1, 2 and 3 obtained in comparative examples were subjected to thermal shrinkage at 180 ℃ for 11h, TMA film breaking temperature test, membrane adhesion test and national standard breakdown voltage test, the 6 types of membranes were assembled into 2.4Ah soft package battery lithium ion batteries, and the 6 types of batteries were subjected to 180 ℃ 15h thermal stability test (no ignition and no explosion were regarded as passed) and room temperature cycle test (cycle 1000 weeks, capacity retention rate). As shown in table 1, the heat resistance, the film breaking temperature and the breakdown voltage of the composite diaphragm can be obviously improved by adding the aramid fiber, and the heat resistance, the film breaking temperature and the breakdown voltage are better and better along with the increase of the adding amount, and it is worth mentioning that the aramid fiber can enable the composite diaphragm battery cell to pass a safety test at 180 ℃ for 15 hours; the addition of PMMA can improve the adhesion of the composite diaphragm, improve the interface performance and further improve the cycle performance; the PMMA composite diaphragm is added only and has great swelling in electrolyte, and the cycle performance is very poor, so that the high heat resistance of the composite diaphragm can be realized through the synergistic effect of blending aramid fiber and a PMMA oily system, and meanwhile, the adhesion of the composite diaphragm is improved. Therefore, the composite diaphragm has the advantages of overall performance: the overall heat resistance, the film breaking temperature, the adhesion and the breakdown voltage are improved, so that the composite diaphragm battery cell has more excellent cycle performance and high-temperature stability.
Table 1 physical property test results of different separators
Figure BDA0003722203830000061
Comparing example 1 with comparative example 3, it can be seen from fig. 1, fig. 3 and fig. 4 that the addition of the cross-linking agent in example 1 can effectively control the pore channels of the coating to be more uniform. Table 1 shows that when the coating of comparative example 1 is compared with that of comparative example 3, the cell is not thermally stable due to the uneven pore morphology of the coating of comparative example 3, and the thermal shrinkage performance of the separator and the cycle performance of the cell are affected by the uneven pore morphology.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (10)

1. A lithium ion battery composite diaphragm is characterized in that: the high-viscosity high-molecular polymer and the high-heat-resistance polymer form a coating to be coated on the surface of the base film, wherein molecular chains of the high-viscosity high-molecular polymer and the high-heat-resistance polymer are mutually wound, and the high-viscosity high-molecular polymer is crosslinked to form a net structure with pore channels on the surface.
2. The lithium ion battery composite separator according to claim 1, wherein: the base film is a PP/PE/PP three-layer co-extrusion base film, a PP1/PP2/PP1 three-layer co-extrusion base film, PP, PE, PET or PI, and the porosity is 40-50%.
3. The lithium ion battery composite separator according to claim 1, wherein: the high-viscosity high polymer is polyacrylate high-viscosity agent.
4. The lithium ion battery composite separator according to claim 1, wherein: the high heat-resistant polymer is
Figure FDA0003722203820000011
5. A preparation method of the lithium ion battery composite membrane of any one of claims 1 to 4 is characterized in that: firstly, dissolving a high-viscosity high-molecular polymer and a high-heat-resistant polymer in an organic solvent, assisting with a pore-forming agent to prepare a coating solution, then coating the coating solution on the surface of a base film, placing the base film in a coagulating bath containing a cross-linking agent, performing coagulation pore-forming, then extracting the pore-forming agent from water, and finally drying to obtain the composite diaphragm.
6. The preparation method of the lithium ion battery composite separator according to claim 5, characterized in that: the mass ratio of the high-viscosity high-molecular polymer to the high-heat-resistant polymer is 5-0.1.
7. The preparation method of the lithium ion battery composite separator according to claim 5, characterized in that: the organic solvent is NMP, DMAC or acetone.
8. The preparation method of the lithium ion battery composite separator according to claim 5, characterized in that: the pore-forming agent is one or a mixture of more than one of polyethylene glycol, terpineol, amine carbonate, ammonium bicarbonate and ammonium oxalate.
9. The preparation method of the lithium ion battery composite separator according to claim 5, characterized in that: the mass ratio of water to NMP in the coagulation bath is (1-9) to 10, and the cross-linking agent accounts for 0.1-20wt% of the sum of the mass of water and NMP.
10. The preparation method of the lithium ion battery composite separator according to claim 9, characterized in that: the cross-linking agent is ethylene glycol dimethacrylate, divinyl benzene, diisocyanate or N, N-methylene bisacrylamide.
CN202210755115.6A 2022-06-30 2022-06-30 Lithium ion battery composite diaphragm and preparation method thereof Pending CN115207571A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105932204A (en) * 2016-06-24 2016-09-07 佛山市金辉高科光电材料有限公司 Composite lithium ion battery separator and preparation method therefor
CN106025149A (en) * 2016-06-30 2016-10-12 深圳中兴创新材料技术有限公司 High-temperature-resistant composite lithium battery diaphragm and preparation method for same
CN110845957A (en) * 2019-11-22 2020-02-28 上海大学 Aqueous aramid fiber coating liquid and preparation method thereof, lithium ion battery and diaphragm thereof
CN113258211A (en) * 2021-05-13 2021-08-13 江苏厚生新能源科技有限公司 High-liquid-storage-rate coated diaphragm and preparation method and application thereof

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105932204A (en) * 2016-06-24 2016-09-07 佛山市金辉高科光电材料有限公司 Composite lithium ion battery separator and preparation method therefor
CN106025149A (en) * 2016-06-30 2016-10-12 深圳中兴创新材料技术有限公司 High-temperature-resistant composite lithium battery diaphragm and preparation method for same
CN110845957A (en) * 2019-11-22 2020-02-28 上海大学 Aqueous aramid fiber coating liquid and preparation method thereof, lithium ion battery and diaphragm thereof
CN113258211A (en) * 2021-05-13 2021-08-13 江苏厚生新能源科技有限公司 High-liquid-storage-rate coated diaphragm and preparation method and application thereof

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Application publication date: 20221018