CN112952284B - Lithium ion battery diaphragm, preparation method thereof and lithium ion battery - Google Patents

Lithium ion battery diaphragm, preparation method thereof and lithium ion battery Download PDF

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CN112952284B
CN112952284B CN201911269549.XA CN201911269549A CN112952284B CN 112952284 B CN112952284 B CN 112952284B CN 201911269549 A CN201911269549 A CN 201911269549A CN 112952284 B CN112952284 B CN 112952284B
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base film
coating
organic polymer
separator
stretching
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CN112952284A (en
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李乐星
孙健
许娇
罗明俊
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Huizhou BYD Battery Co Ltd
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Huizhou BYD Battery 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
    • 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
    • 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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  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Cell Separators (AREA)

Abstract

The invention relates to a lithium ion battery diaphragm and a preparation method thereof, and a lithium ion battery, wherein the diaphragm comprises a base film and a coating, the base film comprises a first surface and a second surface which are opposite in the thickness direction, the base film is provided with a through hole, and the aperture of the through hole is gradually expanded from the first surface to the second surface; a coating overlies the base film and at least a portion of the coating is embedded in the through-holes, the coating containing a first organic polymer. The lithium ion battery diaphragm has good liquid retention and infiltration performance, and has better cohesiveness with the pole piece.

Description

Lithium ion battery diaphragm, preparation method thereof and lithium ion battery
Technical Field
The disclosure relates to the field of lithium ion batteries, in particular to a lithium ion battery diaphragm, a preparation method thereof and a lithium ion battery.
Background
The separator is one of important structures in lithium ion batteries, and is continuously developed along with the updating of the lithium ion batteries. After the material of the separator has undergone a change from polypropylene (PP) to halogenated Polyethylene (PE), lithium ion power batteries today are commonly used with a material made of Al 2 O 3 A coated halogenated polyethylene film. While PVDF is expected to replace Al 2 O 3 As the next-generation coating material of PE film, the prior art generally coats an adhesive layer on the surface of the base film so as to increase the adhesion between the diaphragm and the pole piece, however, the organic coating diaphragm obtained by the coating method has more obvious adhesiveLayers, such obvious layer structures, are prone to powder fall and even fall off during battery winding, slitting, etc., which may lead to short circuits in the battery.
Disclosure of Invention
The invention aims to solve the problems of poor adhesion between an existing diaphragm and a pole piece and poor diaphragm wettability, and provides a lithium ion battery diaphragm, a preparation method thereof and a lithium ion battery.
In order to achieve the above object, a first aspect of the present disclosure provides a lithium ion battery separator comprising a base film and a coating layer, the base film comprising a first surface and a second surface opposite in a thickness direction, the base film having a through hole, a pore diameter of the through hole being gradually enlarged from the first surface to the second surface; the coating overlies the base film and at least a portion of the coating is embedded in the through-hole, the coating comprising a first organic polymer.
Optionally, the aperture of the first surface opening is 20-80nm, and the aperture of the second surface opening is 200-800nm.
Optionally, the peel force between the base film and the coating is 2-8N.
Optionally, the coating covers the second surface.
Optionally, the thickness of the base film is 7-16 μm; the thickness of the coating layer coated on the base film is 0.1-5 mu m.
Optionally, the porosity of the membrane is 40-70%; a tensile strength in the first direction of 1000-2500kg/cm 2 A tensile strength in the second direction of 100-400kg/cm 2 The shrinkage in a first direction is less than 10% and the shrinkage in a second direction is less than 12%, the first direction being perpendicular to the second direction.
Optionally, the first organic polymer comprises one or more of polyethylene oxide, polyvinylidene fluoride-hexafluoropropylene polyvinylidene fluoride, polyimide, polyamide, polytetrafluoroethylene, polyethylene terephthalate, meta-aramid, poly (ethylene terephthalate) diazole and aramid nanofibers;
preferably, the first organic polymer comprises polyethylene oxide and/or polyvinylidene fluoride-hexafluoropropylene.
Optionally, the coating further comprises inorganic particles including one or more of alumina, silica, boehmite, and magnesium hydroxide.
Optionally, the base film contains a second organic polymer, wherein the second organic polymer comprises one or more of halogenated polyethylene, polypropylene, polyethylene oxide, polyvinylidene fluoride-hexafluoropropylene, polyimide, polyamide, polytetrafluoroethylene, polyethylene terephthalate, meta-aramid, poly (ethylene terephthalate) and aramid nanofibers;
preferably, the second organic polymer includes one or more of halogenated polyethylene, polyimide, polyethylene oxide, polyvinylidene fluoride-hexafluoropropylene and polyimide.
A second aspect of the present disclosure provides a method of preparing a separator provided in the first aspect of the present disclosure, the method comprising:
(1) Performing first cooling treatment on the first surface of the second organic polymer film with the micro through holes, and performing second cooling treatment on the second surface of the second organic polymer film with the micro holes to obtain the base film; wherein the temperature of the first cooling process is higher than the temperature of the second cooling process;
(2) And coating the slurry containing the first organic polymer particles on the base film, and carrying out hot pressing treatment on the obtained composite film.
And (2) coating the slurry on the base film through rotary spraying and mirror roller reverse transfer.
Optionally, the method further comprises: stretching the sheet obtained after the hot pressing treatment; the stretching treatment comprises a first direction stretching treatment and a second direction stretching treatment, wherein the first direction stretching treatment is perpendicular to the second direction stretching treatment; the conditions of the stretching treatment include: the stretching multiplying power is 3-6, the stretching speed is 20-40m/min, and the stretching temperature is 100-140 ℃.
Optionally, the temperature of the first cooling treatment is 10-20 ℃ higher than the temperature of the second cooling treatment.
Optionally, the temperature of the first cooling treatment is 20-25 ℃ and the time is 1-3min; the temperature of the second cooling treatment is 5-10 ℃ and the time is 1-3min.
Optionally, the temperature of the hot pressing treatment is 120-150 ℃ and the pressure is 0.4-0.5MPa.
Alternatively, the first organic polymer particles in the slurry have a particle size of 0 to 0.5 μm.
A third aspect of the present disclosure provides a lithium ion battery comprising the separator provided in the first aspect of the present disclosure.
Through the technical scheme, the battery diaphragm and the pole piece have good cohesiveness, and the diaphragm has good infiltration performance and liquid retention performance.
Additional features and advantages of the present disclosure will be set forth in the detailed description which follows.
Drawings
The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification, illustrate the disclosure and together with the description serve to explain, but do not limit the disclosure. In the drawings:
FIG. 1 is an SEM image of a second surface of a base film prepared according to example 1 of the present disclosure;
fig. 2 is an SEM electron micrograph of a first surface of a base film prepared in example 1 of the present disclosure.
Detailed Description
Specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the disclosure, are not intended to limit the disclosure.
A first aspect of the present disclosure provides a lithium ion battery separator comprising a base film and a coating layer, the base film comprising a first surface and a second surface opposite in a thickness direction, the base film having a through hole, the hole diameter of the through hole diverging from the first surface to the second surface; a coating overlies the base film and at least a portion of the coating is embedded in the through-hole, the coating containing a first organic polymer.
According to the present disclosure, embedding the coating in the via means that the via is partially or completely filled with the coating. The lithium ion battery diaphragm comprises the base films with different pore sizes on two sides and the coating at least partially embedded into the pores of the base films, so that the bonding performance of the diaphragm and the pole piece can be effectively improved, and the infiltration performance and the liquid retention performance of the diaphragm and the electrolyte are improved.
According to the present disclosure, the pore diameters of the first surface pores and the second pores may vary within a wide range, and preferably, the pore diameter of the first surface pores is 20 to 80nm and the pore diameter of the second surface pores is 200 to 800nm. More preferably, the first surface openings have a pore size of 20-50nm and the second surface openings may have a pore size of 300-400nm. The aperture of the first surface opening and the aperture of the second surface opening are in the above ranges, so that the separator has good lithium conductivity, and the separator performance is improved.
According to the present disclosure, the separator has a large peel force between the base film and the coating layer, and the peel force between the base film and the coating layer may be 2 to 8N, preferably 3 to 5N. The base film and the coating are combined more tightly in the diaphragm, and the diaphragm has higher strength.
In a preferred embodiment, the coating layer can be coated on the second surface with larger pore diameter and embedded in the pores of the base film, so that the structure ensures good liquid absorption performance of the diaphragm, good air permeability and difficult falling-off.
The thickness of the base film may vary within a wide range, preferably 7-16 μm, more preferably 9-12 μm, according to the present disclosure. The coating layer applied to the base film may be a continuous coating layer or a discontinuous coating layer, and is not limited thereto. The thickness of the coating may also vary within a wide range, for example, from 0.1 to 5. Mu.m, preferably from 0.5 to 5. Mu.m, more preferably from 0.5 to 1. Mu.m. Too thick a separator may cause a decrease in the energy density of the battery, and too thin a separator may cause a decrease in the safety performance of the battery. When the thicknesses of the base film and the coating of the diaphragm are in the above range, the performance of the diaphragm for soaking the electrolyte can be further improved, and the liquid retention amount and the adhesion between the base film and the pole piece are improved. In one embodiment, the coating may further comprise a binder to further enhance the adhesion of the base film to the coating. Binders are well known to those skilled in the art and will not be described in detail herein.
According to the present disclosure, the porosity of the separator may be 40-70%, preferably 50-60%; the tensile strength in the first direction may be 1000-2500kg/cm 2 Preferably 1000-2000kg/cm 2 More preferably 1400-2000kg/cm 2 A tensile strength in the second direction of 100-400kg/cm 2 Preferably 150-300kg/cm 2 . The shrinkage in the first direction is less than 10%, preferably 7-9%, and the shrinkage in the second direction is less than 12%, preferably 9-11%, the first direction being perpendicular to the second direction.
The first organic polymer contained in the coating layer may be conventionally employed by those skilled in the art in light of the present disclosure, and for example, the first organic polymer may include one or more of polyethylene oxide (PEO), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyimide (PI), polyamide (PA), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), meta-aramid (PMIA), polyoxadiazole (PBO), and Aramid Nanofibers (ANF).
In one embodiment, the first organic polymer may include polyethylene oxide (PEO) and/or polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP). The first organic polymer of the type can further improve the bonding performance of the diaphragm and the pole piece and the liquid retention capacity of the diaphragm.
The coating may also contain inorganic particles, which may be conventionally employed by those skilled in the art, including, for example, one or more of alumina, silica, boehmite, and magnesium hydroxide, in accordance with the present disclosure. The particle diameter of the inorganic particles is not particularly limited, and for example, the extremely poor particle diameter of the inorganic particles may be 0 to 0.5 μm, and the particle diameter of the inorganic particles has good uniformity when in the above-mentioned range, which is advantageous in reducing the ventilation value of the separator to a more suitable range and further improving the liquid retention amount of the separator. The inorganic particles can be sprayed on the diaphragm by adopting an ion sputtering mode.
The second organic polymer contained in the base film may be conventionally employed by those skilled in the art, preferably an olefin polymer having a high molecular weight, for example, the second organic polymer includes one or more of halogenated Polyethylene (PE), polypropylene (PP), polyethylene oxide (PEO), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyimide (PI), polyamide (PA), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), meta-aramid (PMIA), polyoxadiazole (PBO), and Aramid Nanofiber (ANF).
In one embodiment, the second organic polymer may use one or more selected from halogenated Polyethylene (PE), polypropylene (PP), polyethylene oxide (PEO), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), and Polyimide (PI). The base film containing the polymer has higher stiffness, excellent appearance and better stretching performance, and can improve the production line speed of film products.
A second aspect of the present disclosure provides a method of preparing a separator provided in the first aspect of the present disclosure, the method comprising:
(1) Performing first cooling treatment on the first surface of the second organic polymer film with the micro through holes, and performing second cooling treatment on the second surface of the second organic polymer film with the micro holes to obtain a base film; wherein the temperature of the first cooling process is higher than the temperature of the second cooling process;
(2) And coating the slurry containing the first organic polymer particles on the base film, and carrying out hot pressing treatment on the obtained composite film.
The disclosed method can make the pore sizes of the two sides of the base film different through the first cooling treatment and the second cooling treatment, and then the coating is embedded into the pores of the base film through the subsequent hot pressing treatment. The method of the present disclosure can produce a separator having good liquid retention, adhesion, and a low heat shrinkage.
The method for producing the second organic polymer film having micropores is not limited, and for example, the second organic polymer film having microperforations can be produced by mixing a pore-forming agent with the second organic polymer and then extruding the mixture to produce an organic polymer film, and removing the pore-forming agent. The pore-forming agent may be, for example, white oil or kerosene. The method for removing the pore-forming agent is not limited either: when the pore former is white oil, the membrane may be washed after the autoclave of step (2) with an organic solvent, such as heptane, which is well known to those skilled in the art, to remove the white oil; when the pore-forming agent is kerosene, it may be subjected to heat treatment after extrusion to prepare an organic polymer film so that kerosene is removed by volatilization.
According to the present disclosure, the slurry may be coated on the base film by spin coating and mirror roll reverse transfer in step (2). Spin coating and mirror roll reversal are well known to those skilled in the art and will not be described in detail herein. In a preferred embodiment, the slurry comprising the second organic polymer particles is applied by spin coating to a chilled roll and then reverse transferred to a base film by a mirror roll to further improve the uniformity of the coating during subsequent preparation.
According to the present disclosure, the method may further comprise: stretching the sheet obtained after the hot pressing treatment; the stretching treatment includes a first direction stretching treatment and a second direction stretching treatment, the first direction stretching treatment being perpendicular to the second direction stretching treatment. The first stretching treatment and the second stretching treatment may be performed simultaneously or may not be performed simultaneously. The conditions of the stretching treatment may include: the stretching multiplying power is 3-6, the stretching speed is 20-40m/min, and the stretching temperature is 100-140 ℃. Preferably, the stretching ratio is 4-5, the stretching rate is 25-35m/min, and the stretching temperature is 100-110 ℃. Stretching treatments are well known to those skilled in the art and may be performed, for example, by placing the separator on a stretching roller. When the stretching roller is used for the first stretching treatment, the running direction of the diaphragm on the stretching roller is a first direction, and the axial direction of the stretching roller is a second direction. The operating parameters of the first stretching process may be the same as or different from the operating parameters of the second stretching process. In one embodiment, the first stretching treatment has a stretching ratio of 5-6, a stretching rate of 20-40m/min, and a stretching temperature of 100-110 ℃. The stretching multiplying power of the second stretching treatment is 4-5, the stretching speed is 20-40m/min, and the stretching temperature is 100-140 ℃. The membrane can be further reamed through stretching treatment, so that the coating embedded in the through hole can be uniformly distributed and filled on the inner surface of the through hole, and the membrane has better air permeability and liquid retention.
According to the present disclosure, the temperature of the first cooling process may be 10-20 ℃ higher than the temperature of the second cooling process, and preferably, the temperature of the first cooling process may be 15-20 ℃ higher than the temperature of the second cooling process. The two sides of the base film are treated at different cooling treatment temperatures, so that the pore sizes of the openings on the two sides are different, and the liquid absorption rate of the diaphragm is improved.
In a preferred embodiment, the temperatures and times of the first cooling treatment and the second cooling treatment may vary within a wide range, preferably the temperature of the first cooling treatment is 20-25 ℃, the temperature of the second cooling treatment is 5-10 ℃, more preferably the temperature of the first cooling treatment is 23-25 ℃, and the temperature of the second cooling treatment is 5-7 ℃. The time of the first cooling treatment may be 1 to 3 minutes, the time of the second cooling treatment may be 1 to 3 minutes, preferably, the time of the first cooling treatment is 1.5 to 2.5 minutes, and the time of the second cooling treatment is 1.5 to 2.5 minutes. The cooling treatment mode is not particularly limited, for example, the first cooling treatment is water bath cooling, the second cooling treatment is rapid cooling, the rapid cooling can adopt a method of refrigerating by a refrigerant, and the refrigerant can be one or more of liquid nitrogen, freon-12, R134a and R404 a.
According to the present disclosure, the hot pressing treatment may be performed by using a pressing roller, and the temperature of the hot pressing treatment may be varied within a wide range, preferably 120 to 150 ℃, and more preferably 130 to 140 ℃; the pressure may be from 0.4 to 0.5MPa, preferably from 0.45 to 0.5MPa. The autoclave may embed at least a portion of the coating into the through-hole to increase the liquid retention and wettability of the separator.
According to the present disclosure, the first organic polymer particles in the slurry may have a very poor particle size of 0 to 0.5 μm, preferably 0 to 0.25 μm. The particle size of the first organic polymer particles in the slurry is extremely poor, and the particle size of the first organic polymer particles in the slurry is in the range, so that the uniformity is good, the first organic polymer particles are uniformly filled in holes of the separator, and the lithium ion battery separator with better liquid retention and wettability is prepared. In one embodiment, the first organic polymer may be screened by ball milling to provide a particle size that is within a specified range. And mixing the screened first organic polymer with a dispersing agent and a binder to obtain slurry.
A third aspect of the present disclosure provides a lithium ion battery comprising the separator provided in the second aspect of the present disclosure.
In a specific embodiment, a positive electrode, a diaphragm and a negative electrode are sequentially overlapped and wound into a roll, and then the roll is prepared into a lithium ion battery through a shell, liquid injection, sealing and formation.
The present disclosure is further illustrated by the following examples, but the present disclosure is not limited thereby.
The halogenated polyethylenes in examples and comparative examples were purchased from Celanese, polyvinylidene fluoride from suwei, PEO from flower king.
Example 1
The white oil was mixed with polyethylene (weight average molecular weight 250000, molecular weight dispersion index 12) and then extruded through a twin screw extruder to prepare a second organic polymer film having micro-holes.
And (3) placing the second organic polymer film with the micro-through holes on the surface of a chilled roller to be pulled by the surface of the chilled roller, performing water cooling treatment on the first surface of the second organic polymer film at 25 ℃ for 2min, and performing chilling treatment on the second surface at 5 ℃ for 2min. A slurry containing polyvinylidene fluoride particles (with the extremely small particle diameter of 0.2 μm), ethanol (a dispersing agent) and styrene-butadiene rubber (SBR) is coated on the second surface of the second organic polymer film by means of rotary spraying and mirror reverse transfer, and then aluminum oxide is sprayed on the surface of the second organic polymer coated with the slurry by means of ion sputtering, so that a base film is prepared.
And (3) carrying out hot pressing treatment on the base film by adopting a hot pressing device at the temperature of 130 ℃ and the pressure of 0.5MPa to obtain the sheet with the coating partially embedded into the holes of the base film. The sheet is subjected to a first direction stretching process and a second direction stretching process, the first direction being perpendicular to the second direction. Wherein the stretching multiplying power of the first direction stretching treatment is 5, the stretching speed is 20m/min, and the stretching temperature is 120 ℃; the stretching ratio of the second direction stretching treatment was 5, the stretching rate was 20m/min, and the stretching temperature was 120 ℃. And (3) allowing the membrane after the stretching treatment to pass through an extraction tank filled with heptane to remove white oil in the membrane, and finally obtaining the finished membrane A.
The membrane had a base film thickness of 16 μm and a coating thickness of 1. Mu.m. SEM electron micrographs of the first and second surfaces of the base film are shown in fig. 1 and 2, respectively.
Example 2
A separator B was prepared in the same manner as in example 1 except that the first surface of the second organic polymer film was subjected to water cooling treatment at 20 ℃ for 2min and the second surface was chilled at 15 ℃ for 2min.
The base film thickness of the separator B was 16 μm and the coating thickness was 1. Mu.m.
Example 3
A separator C was prepared in the same manner as in example 1 except that alumina was sprayed onto the second surface of the second organic polymer coated with the slurry by means of ion sputtering, and then a slurry containing polyvinyl chloride particles (particle size range of 0.2 μm), ethanol (dispersant) and styrene-butadiene rubber (binder) was coated onto the first surface of the second organic polymer film by means of spin spraying and mirror reverse transfer to prepare a base film.
The membrane C had a base film thickness of 16 μm and a coating thickness of 1. Mu.m.
Example 4
A separator D was prepared in the same manner as in example 1 except that the base film was subjected to a heat press treatment by a heat press device at a temperature of 100 ℃ and a pressure of 0.3MPa to obtain a separator in which the coating layer was partially embedded in the pores of the base film.
The membrane D had a base film thickness of 16 μm and a coating thickness of 1. Mu.m.
Comparative example 1
The separator a was prepared using gravure roll coating. The base film thickness of the separator a was 16 μm and the coating thickness was 1. Mu.m.
Comparative example 2
A separator b was prepared in the same manner as in example 1 except that both the first surface and the second surface of the second organic polymer film were subjected to water-cooling treatment at 10 c for 2min.
The base film thickness of the separator b was 16 μm and the coating thickness was 1. Mu.m.
Comparative example 3
Separator c was prepared in the same manner as in example 1, except that the base film was not subjected to heat press treatment.
The membrane c had a base film thickness of 18 μm and a coating thickness of 2. Mu.m.
Preparation example
The separators prepared in examples and comparative examples were stacked with a positive electrode and a negative electrode, respectively, wound into rolls, and then prepared into lithium ion batteries by casing, liquid injection, sealing, and formation. The positive electrode active material is NCM811, the negative electrode is a graphite negative electrode, and the electrolyte is lithium hexafluorophosphate.
Test case
(1) Diaphragm peel force test
The separator peel force was tested using the GB/T2792-81 pressure sensitive adhesive tape 180 peel strength test method. Specifically, peel strength test tape: a single-sided tape having a tack of 0.4.+ -. 0.05N/mm and a width of 19.+ -. 0.5mm was used as the peel strength of the sample at a test speed of 50.+ -.5 mm/min and a peel length of 100.+ -.10 mm, with an average value of 3 samples.
(2) Testing of battery capacity
The battery capacity was tested in a wuhan blue electric battery test system (Land-CT 2001B) at a temperature of 0℃ to 0.5C and the battery cycled 10 times.
(3) Adhesion test of diaphragm and pole piece
Tension machine: the measuring range of the sensor is less than 200N; the resolution of the sensor is 0.01N, and the precision is +/-0.5%.
Test tape: a single-sided tape with a tack of 0.4.+ -. 0.05N/mm and a width of 19.+ -. 0.5 mm.
TABLE 1
Figure BDA0002313784840000111
The base film containing the second organic polymer in the separator of the present disclosure has hydrophobicity itself, and the polar solvent contained in the electrolyte is weak to its wettability and liquid retention. The first organic polymer embedded in the base film is a polar molecule, has better wettability and liquid retention to electrolyte, so that the separator disclosed by the disclosure has better liquid retention capacity. The separator and the pole piece also have good cohesiveness.
The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, but the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solutions of the present disclosure within the scope of the technical concept of the present disclosure, and all the simple modifications belong to the protection scope of the present disclosure.
In addition, the specific features described in the foregoing embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, the present disclosure does not further describe various possible combinations.
Moreover, any combination between the various embodiments of the present disclosure is possible as long as it does not depart from the spirit of the present disclosure, which should also be construed as the disclosure of the present disclosure.

Claims (15)

1. A lithium ion battery separator, characterized in that the separator comprises a base film and a coating, wherein the base film comprises a first surface and a second surface which are opposite in the thickness direction, the base film is provided with a through hole, the pore diameter of the through hole gradually expands from the first surface to the second surface, the pore diameter of an opening of the first surface is 20-80nm, and the pore diameter of an opening of the second surface is 200-800nm; the coating is coated on the base film, at least part of the coating is embedded in the through hole, and the coating contains a first organic polymer;
the first organic polymer comprises one or more of polyethylene oxide, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride, polyimide, polyamide, polytetrafluoroethylene, polyethylene terephthalate, meta-aramid, poly (ethylene terephthalate) diazole and aramid nanofibers;
the coating covers the second surface; the base film contains a second organic polymer, and the second organic polymer comprises one or more of polyethylene and polypropylene.
2. The membrane of claim 1, wherein the first surface openings have a pore size of 20-50nm and the second surface openings have a pore size of 300-400nm.
3. The separator of claim 1, wherein the peel force between the base film and the coating is 2-8N.
4. The separator according to claim 1, wherein the base film has a thickness of 7-16 μm; the thickness of the coating layer coated on the base film is 0.1-5 mu m.
5. The separator of claim 1, wherein the separator has a porosity of 40-70%; a tensile strength in the first direction of 1000-2500kg/cm 2 A tensile strength in the second direction of 100-400kg/cm 2 The shrinkage in a first direction is less than 10% and the shrinkage in a second direction is less than 12%, the first direction being perpendicular to the second direction.
6. The separator according to claim 1, wherein the first organic polymer comprises polyethylene oxide and/or polyvinylidene fluoride-hexafluoropropylene.
7. The separator of claim 1, wherein the coating further comprises inorganic particles comprising one or more of alumina, silica, boehmite, and magnesium hydroxide.
8. A method of making the separator of any one of claims 1-7, comprising:
(1) Performing first cooling treatment on the first surface of the second organic polymer film with the micro through holes, and performing second cooling treatment on the second surface of the second organic polymer film with the micro holes to obtain the base film; wherein the temperature of the first cooling process is higher than the temperature of the second cooling process;
(2) And coating the slurry containing the first organic polymer particles on the base film, and carrying out hot pressing treatment on the obtained composite film.
9. The method of claim 8, wherein the slurry is applied to the base film in step (2) by spin coating and mirror roll reverse transfer.
10. The method of claim 8, wherein the method further comprises: stretching the sheet obtained after the hot pressing treatment; the stretching treatment comprises a first direction stretching treatment and a second direction stretching treatment, wherein the first direction stretching treatment is perpendicular to the second direction stretching treatment; the conditions of the stretching treatment include: the stretching multiplying power is 3-6, the stretching speed is 20-40m/min, and the stretching temperature is 100-140 ℃.
11. The method of claim 8, wherein the temperature of the first cooling process is 10-20 ℃ higher than the temperature of the second cooling process.
12. The method according to any one of claims 8 to 11, wherein the temperature of the first cooling treatment is 20 to 25 ℃ for 1 to 3 minutes; the temperature of the second cooling treatment is 5-10 ℃ and the time is 1-3min.
13. The method according to claim 8, wherein the autoclave is at a temperature of 120-150 ℃ and a pressure of 0.4-0.5MPa.
14. The method of claim 8, wherein the first organic polymer particles in the slurry have a particle size range of 0 to 0.5 μm.
15. A lithium ion battery comprising the separator of any one of claims 1-7.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5514461A (en) * 1993-10-05 1996-05-07 Kureha Chemical Industry Co., Ltd. Vinylidene fluoride porous membrane and method of preparing the same
CN101212035A (en) * 2006-12-29 2008-07-02 比亚迪股份有限公司 Battery isolating film and method for producing the same
CN101752539A (en) * 2008-12-01 2010-06-23 比亚迪股份有限公司 Polyimide diaphragm for lithium ion secondary battery and lithium ion battery
CN106898721A (en) * 2017-02-28 2017-06-27 沧州明珠隔膜科技有限公司 A kind of lithium ion battery separator for being suitable to hot dry-pressing and preparation method thereof

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5514461A (en) * 1993-10-05 1996-05-07 Kureha Chemical Industry Co., Ltd. Vinylidene fluoride porous membrane and method of preparing the same
CN101212035A (en) * 2006-12-29 2008-07-02 比亚迪股份有限公司 Battery isolating film and method for producing the same
CN101752539A (en) * 2008-12-01 2010-06-23 比亚迪股份有限公司 Polyimide diaphragm for lithium ion secondary battery and lithium ion battery
CN106898721A (en) * 2017-02-28 2017-06-27 沧州明珠隔膜科技有限公司 A kind of lithium ion battery separator for being suitable to hot dry-pressing and preparation method thereof

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