CN112332023B - Ultrathin high-strength modified lithium ion battery diaphragm and preparation method thereof - Google Patents
Ultrathin high-strength modified lithium ion battery diaphragm and preparation method thereof Download PDFInfo
- Publication number
- CN112332023B CN112332023B CN202011241175.3A CN202011241175A CN112332023B CN 112332023 B CN112332023 B CN 112332023B CN 202011241175 A CN202011241175 A CN 202011241175A CN 112332023 B CN112332023 B CN 112332023B
- Authority
- CN
- China
- Prior art keywords
- diaphragm
- lithium ion
- ion battery
- treatment
- weight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical class [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 38
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- 238000011282 treatment Methods 0.000 claims abstract description 41
- 238000003682 fluorination reaction Methods 0.000 claims abstract description 25
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical class O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 24
- 239000004699 Ultra-high molecular weight polyethylene Substances 0.000 claims abstract description 20
- 229920000785 ultra high molecular weight polyethylene Polymers 0.000 claims abstract description 20
- 239000000203 mixture Substances 0.000 claims abstract description 13
- 238000001035 drying Methods 0.000 claims abstract description 12
- 238000001125 extrusion Methods 0.000 claims abstract description 10
- 238000002156 mixing Methods 0.000 claims abstract description 9
- 238000007493 shaping process Methods 0.000 claims abstract description 9
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000003963 antioxidant agent Substances 0.000 claims abstract description 8
- 230000003078 antioxidant effect Effects 0.000 claims abstract description 8
- 230000008878 coupling Effects 0.000 claims abstract description 8
- 238000010168 coupling process Methods 0.000 claims abstract description 8
- 238000005859 coupling reaction Methods 0.000 claims abstract description 8
- 229910000077 silane Inorganic materials 0.000 claims abstract description 8
- 238000005266 casting Methods 0.000 claims abstract description 7
- 238000005096 rolling process Methods 0.000 claims abstract description 7
- 238000005406 washing Methods 0.000 claims abstract description 4
- -1 polyethylene Polymers 0.000 claims description 21
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 20
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 20
- 238000000034 method Methods 0.000 claims description 19
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 claims description 18
- 239000004698 Polyethylene Substances 0.000 claims description 17
- 229920000573 polyethylene Polymers 0.000 claims description 17
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 12
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 10
- 229910052731 fluorine Inorganic materials 0.000 claims description 10
- 239000011737 fluorine Substances 0.000 claims description 10
- 239000007789 gas Substances 0.000 claims description 9
- 239000012528 membrane Substances 0.000 claims description 9
- 230000008569 process Effects 0.000 claims description 7
- 239000012982 microporous membrane Substances 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- 238000011049 filling Methods 0.000 claims description 2
- 239000000155 melt Substances 0.000 claims description 2
- 239000003792 electrolyte Substances 0.000 abstract description 15
- 230000014759 maintenance of location Effects 0.000 abstract description 11
- 239000003921 oil Substances 0.000 description 25
- 239000000463 material Substances 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 13
- 239000007788 liquid Substances 0.000 description 9
- 229910001416 lithium ion Inorganic materials 0.000 description 9
- 239000000243 solution Substances 0.000 description 9
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 8
- 229910052744 lithium Inorganic materials 0.000 description 8
- 239000000377 silicon dioxide Substances 0.000 description 8
- 229920000098 polyolefin Polymers 0.000 description 7
- 125000001153 fluoro group Chemical group F* 0.000 description 6
- 235000012239 silicon dioxide Nutrition 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 239000004743 Polypropylene Substances 0.000 description 4
- 238000000605 extraction Methods 0.000 description 4
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 4
- 239000011159 matrix material Substances 0.000 description 4
- 229920001155 polypropylene Polymers 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 229910013872 LiPF Inorganic materials 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
- 239000006087 Silane Coupling Agent Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000007600 charging Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010277 constant-current charging Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000005213 imbibition Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 239000012779 reinforcing material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- 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 an ultrathin high-strength modified lithium ion battery diaphragm and a preparation method thereof, and the preparation method comprises the following steps: uniformly mixing 60-80 parts by weight of ultrahigh molecular weight polyethylene, 20-40 parts by weight of ultrahigh molecular weight polyethylene, 5-10 parts by weight of silane coupling modified fumed silica, 0.1-0.5 part by weight of antioxidant and 200-400 parts by weight of white oil to obtain a mixture, carrying out melt extrusion, obtaining a thick sheet through sheet casting, then carrying out biaxial tension treatment, removing the white oil, carrying out traction shaping, rolling and slitting to obtain the microporous diaphragm with the film thickness of less than 4 mu m; and carrying out fluorination treatment on the microporous diaphragm to obtain a fluorinated microporous diaphragm, then carrying out irradiation grafting treatment, washing and drying to obtain the ultrathin high-strength modified lithium ion battery diaphragm. The modified diaphragm has high puncture strength, good electrolyte wettability and good hydraulic retention.
Description
Technical Field
The invention relates to the technical field of high polymer materials, in particular to an ultrathin high-strength modified lithium ion battery diaphragm and a preparation method thereof.
Background
The lithium ion battery is widely applied to various portable electronic products and communication equipment as a high-performance green battery, and is also a preferred power source of hybrid electric vehicles and electric vehicles. Along with the rapid development of the lithium ion battery industry, research and development on improvement of the lithium ion battery are increasingly deep. The separator plays three main roles in lithium batteries: isolating the positive and negative pole pieces; isolating electrons from freely passing through; the micropores of the diaphragm can allow ions in the electrolyte to freely pass between the anode and the cathode. The performance of the diaphragm and the microporous structure thereof directly determine the internal resistance of the lithium ion battery, and the capacity, the cycle performance and the charge and discharge efficiency of the battery can be further influenced, so that the research on the performance of the diaphragm and the microporous structure thereof is concerned.
Polyolefin materials have excellent properties such as high strength, acid and alkali resistance, good corrosivity, water resistance, chemical reagent resistance, good biocompatibility, nontoxicity, and the like, and have been widely used in many fields. Within a reasonable cost range, the polyolefin compound has better tear resistance, lower surface resistance, good mechanical property and chemical stability, and high-temperature self-closing property, so that the safety of the lithium ion battery in daily use is ensured. Most commercial liquid lithium ion batteries use microporous polyolefin separators.
Currently, the diaphragm materials used by lithium ion batteries are mainly polyethylene and polypropylene. According to the characteristics of the material, the preparation of the diaphragm made of the polypropylene material is generally carried out by adopting a dry-process stretching process, and the preparation of the diaphragm made of the polyethylene material is carried out by adopting a wet-process stretching process. Meanwhile, the polyethylene material and the polypropylene material can be compounded to be used for manufacturing a double-layer film and a three-layer film, and the double-layer film and the three-layer film provide a protection function for the battery according to the difference of the melting points of the polyethylene and the polypropylene. However, the polyolefin material diaphragm is easily broken down in the charging and discharging process to cause short circuit of the battery core, and meanwhile, because the temperature of the battery core is increased rapidly, the polyolefin diaphragm cannot meet the production requirement due to the lower melting point of the polyolefin diaphragm. In addition, because the polyolefin material is a nonpolar material, the wettability and the liquid retention of the electrolyte are poor, so that the contact surface between the diaphragm and the electrolyte is small, and the internal resistance of the lithium battery at a small level cannot be ensured, thereby further influencing the charge-discharge cycle performance and the capacity of the battery. Finally, as the market has higher and higher requirements on the energy density and the safety of the lithium battery, lithium battery manufacturers also put forward higher requirements on the performance of the diaphragm, namely, the requirements on thinness, higher strength and lower heat shrinkage rate. The membrane on the market is 5 μm at the thinnest, and the thinner membrane is rarely reported and applied.
Disclosure of Invention
The ultrathin high-strength modified lithium ion battery diaphragm and the preparation method thereof are provided for solving the technical problems that a polyethylene material is easy to break down when being used as the diaphragm, has poor wettability and liquid retention of electrolyte and meets the requirements on the diaphragm to be light and thin. The lithium ion battery diaphragm prepared by the method has the thickness of less than 4 mu m, and has higher puncture strength and better electrolyte wettability and hydraulic retention.
In order to achieve the purpose, the invention is realized by the following technical scheme:
the preparation method of the ultrathin high-strength modified lithium ion battery diaphragm comprises the following steps:
(1) uniformly mixing 60-80 parts by weight of ultrahigh molecular weight polyethylene, 20-40 parts by weight of ultrahigh molecular weight polyethylene, 5-10 parts by weight of silane coupling modified fumed silica, 0.1-0.5 part by weight of antioxidant and 200-400 parts by weight of white oil to obtain a mixture;
(2) conveying the mixture to a screw extruder for melt extrusion, obtaining a thick sheet by sheet casting, then carrying out biaxial tension treatment on the thick sheet, removing white oil, carrying out traction shaping, rolling and slitting to obtain a microporous diaphragm with the thickness of less than 4 mu m;
(3) and carrying out fluorination treatment on the microporous diaphragm to obtain a fluorinated microporous diaphragm, then carrying out irradiation grafting treatment, washing and drying to obtain the ultrathin high-strength modified lithium ion battery diaphragm.
Further, the temperature of the melt extrusion in the step (2) is 180-240 ℃.
Further, the biaxial stretching treatment in the step (2) is to longitudinally stretch the thick sheet by 7 to 15 times and then transversely stretch the thick sheet by 7 to 15 times.
Further, the process of removing the white oil in the step (2) is as follows: the biaxially oriented film was placed in methylene chloride to extract white oil.
Further, the step (2) further comprises performing a second transverse stretching by 1.1-2 times after the white oil is removed.
Further, the process of drawing and shaping in the step (2) is that the film is drawn to pass through a hot roller at the temperature of 40-120 ℃ and then pass through a cold roller below 40 ℃.
Further, the fluorination treatment in step (3) is carried out by the following steps: placing the microporous diaphragm in a fluorination instrument which is preheated and then is introduced with nitrogen, filling fluorine gas to 2 kPa-5 kPa at normal temperature to perform fluorination reaction for 30-270 s, and performing the fluorination treatment at least once.
Further, the irradiation grafting treatment in the step (3) is: placing the fluorinated microporous membrane in a polyvinyl alcohol solution for microwave treatment, wherein the frequency of the microwave treatment is 800 MHz-1200 MHz, the power is 500W-800W, and the time is 2 min-5 min; or the fluorinated microporous membrane is firstly subjected to plasma beam treatment, and then the treated membrane is placed in a polyvinyl alcohol solution at the temperature of 50-80 ℃ to be stirred and react for 2-5 min, wherein the current intensity of the plasma beam treatment is 10-15A, and the time is 1-3 min; the mass concentration of the polyvinyl alcohol solution is 5-30%.
The invention also provides an ultrathin high-strength modified lithium ion battery diaphragm prepared by the preparation method, wherein the modified lithium ion battery diaphragm is a polyethylene diaphragm surface grafted
The thickness of the group is less than 4 μm, and the modified lithium ion battery separator can be used as a separator alone or can be used together with separators with other thicknesses.
The beneficial technical effects are as follows:
the modified lithium ion battery diaphragm of the invention adopts ultra-high molecular weight polyethylene and ultra-high molecular weight polyethylene as the base materials of the battery diaphragm, because the molecular weights of the ultra-high molecular weight polyethylene and ultra-high molecular weight polyethylene are higher, the diaphragm has better mechanical strength and heat resistance, silicon dioxide is used as a reinforcing material, and an antioxidant is used for endowing the material with higher mechanical strength and heat resistance; the invention uses screw extrusion blending dispersion technology to uniformly disperse silicon dioxide in a polyethylene matrix, the gas phase method silicon dioxide is a nano-grade material, the silicon dioxide activated by silane coupling agent can reduce the agglomeration among nano particles to more uniformly disperse the silicon dioxide in the polyethylene matrix, after melting blending, the silicon dioxide is subjected to biaxial tension treatment, because the ultrahigh molecular weight polyethylene and the ultrahigh molecular weight polyethylene have better mechanical strength and can bear the tension with larger multiplying power without cracking, under the condition of no pore-forming agent, the stretched film has micropores, then the surface of the microporous diaphragm is fluorinated through the fluorination treatment, hydrogen atoms in the polyethylene matrix are replaced by fluorine atoms, the fluorinated polyethylene microporous diaphragm has certain polarity, then the film and polyvinyl alcohol are subjected to irradiation grafting treatment, the fluorine atoms on the surface of the fluorinated polyethylene microporous diaphragm are combined with the hydrogen atoms on the hydroxyl groups of the polyvinyl alcohol after irradiation, one part of hydrogen fluoride is generated, the macromolecular chain of polyvinyl alcohol is grafted to the surface of the microporous diaphragm, the obtained modified diaphragm can achieve higher puncture strength and tensile strength when the film thickness is below 4 mu m, and simultaneously has lower thermal shrinkage rate and better heat resistance, in addition, after fluorination treatment, surface fluorine atoms become active points, the macromolecular chain can be grafted on fluorine active sites through irradiation treatment, and the obtained modified diaphragm has better wettability and liquid retention capacity on electrolyte.
The modified lithium ion battery diaphragm has higher puncture strength and tensile strength, lower heat shrinkage rate and better heat resistance on the basis of the film thickness of less than 4 mu m, has stronger affinity with electrolyte, better wettability and strong liquid retention capacity, ensures that a lithium battery has lower internal resistance and higher ionic conductivity during operation, and further ensures the charge-discharge cycle performance and capacity of the battery.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Unless specifically stated otherwise, the numerical values set forth in these examples do not limit the scope of the invention. Techniques, methods known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.
The experimental methods of the following examples, which are not specified under specific conditions, are generally determined according to national standards; if no corresponding national standard exists, the method is carried out according to the universal international standard or the standard requirement proposed by related enterprises. Unless otherwise indicated, all parts are parts by weight and all percentages are percentages by weight.
Example 1
The preparation method of the ultrathin high-strength modified lithium ion battery diaphragm comprises the following steps:
(1) uniformly mixing 60 parts by weight of ultrahigh molecular weight polyethylene, 40 parts by weight of ultrahigh molecular weight polyethylene, 5 parts by weight of silane coupling modified fumed silica, 0.1 part by weight of antioxidant and 400 parts by weight of white oil to obtain a mixture;
(2) conveying the mixture to a screw extruder, carrying out melt extrusion at 200 ℃, obtaining a thick sheet by casting the sheet, longitudinally stretching the thick sheet by 10 times to obtain a thin sheet, transversely stretching the thin sheet by 9 times to obtain an oil-containing film, placing the oil-containing film in dichloromethane for white oil extraction, drying the oil-containing film to obtain a dry film, transversely stretching the dry film by 1.2 times to obtain a microporous film, drawing the microporous film to pass through a hot roller at 60 ℃, shaping the microporous film by a cold roller below 30 ℃, and rolling and slitting the microporous film to obtain the ultrathin microporous diaphragm;
(3) placing the microporous diaphragm in a fluorination instrument which is preheated and then is introduced with nitrogen, introducing fluorine gas to 2kPa for fluorination reaction for 120s at normal temperature, then introducing fluorine gas to 2.5kPa for fluorination reaction for 60s to obtain the fluorinated microporous diaphragm, placing the fluorinated microporous diaphragm with the diameter of 8cm multiplied by 8cm in 100g and 10 wt% of polyvinyl alcohol solution for microwave treatment with the frequency of 1000MHz, the power of 800W and the time of 3min, placing the diaphragm in clear water with the temperature of 60 ℃ for washing away unreacted polyvinyl alcohol on the surface of the diaphragm after irradiation grafting treatment, and drying to obtain the ultrathin high-strength modified lithium ion battery diaphragm.
Example 2
The preparation method of the ultrathin high-strength modified lithium ion battery diaphragm comprises the following steps:
(1) uniformly mixing 70 parts by weight of ultrahigh molecular weight polyethylene, 30 parts by weight of ultrahigh molecular weight polyethylene, 10 parts by weight of silane coupling modified fumed silica, 0.3 part by weight of antioxidant and 300 parts by weight of white oil to obtain a mixture;
(2) conveying the mixture to a screw extruder, carrying out melt extrusion at 220 ℃, obtaining a thick sheet by casting the sheet, longitudinally stretching the thick sheet by 12 times to obtain a sheet, transversely stretching the sheet by 10 times to obtain an oil-containing film, placing the oil-containing film in dichloromethane for extraction of white oil, drying the oil-containing film to obtain a dry film, transversely stretching the dry film by 1.1 times to obtain a microporous film, drawing the microporous film to pass through a hot roller at 80 ℃, shaping the microporous film by a cold roller below 30 ℃, and rolling and slitting the microporous film to obtain the ultrathin microporous diaphragm;
(3) placing the microporous diaphragm in a fluorination instrument which is preheated and then is introduced with nitrogen, introducing fluorine gas to 4kPa at normal temperature to perform fluorination reaction for 250s to obtain the fluorinated microporous diaphragm, treating 8cm multiplied by 8cm of the fluorinated microporous diaphragm under a plasma beam with the current intensity of 12A for 2min, then placing the treated diaphragm in 100g of 20 wt% polyvinyl alcohol solution at 60 ℃ to perform stirring reaction for 3min, placing the diaphragm in clear water at 60 ℃ to remove unreacted polyvinyl alcohol on the surface of the diaphragm after irradiation grafting treatment, and drying to obtain the ultrathin high-strength modified lithium ion battery diaphragm.
Example 3
(1) Uniformly mixing 80 parts by weight of ultrahigh molecular weight polyethylene, 20 parts by weight of ultrahigh molecular weight polyethylene, 8 parts by weight of silane coupling modified fumed silica, 0.5 part by weight of antioxidant and 350 parts by weight of white oil to obtain a mixture;
(2) conveying the mixture to a screw extruder, carrying out melt extrusion at 210 ℃, obtaining a thick sheet by casting the sheet, longitudinally stretching the thick sheet for 15 times to obtain a thin sheet, transversely stretching the thin sheet for 13 times to obtain an oil-containing film, placing the oil-containing film in dichloromethane for white oil extraction, drying the oil-containing film to obtain a dry film, transversely stretching the dry film for 1.1 times to obtain a microporous film, drawing the microporous film to pass through a hot roller at 100 ℃, shaping the microporous film by a cold roller below 30 ℃, and rolling and slitting the microporous film to obtain the ultrathin microporous diaphragm;
(3) placing the microporous diaphragm in a fluorination instrument which is preheated and then is introduced with nitrogen, introducing fluorine gas to 2kPa for fluorination reaction for 180s at normal temperature, then introducing fluorine gas to 3kPa for fluorination reaction for 30s to obtain the fluorinated microporous diaphragm, placing the fluorinated microporous diaphragm with the diameter of 8cm multiplied by 8cm in 100g of 30 wt% polyvinyl alcohol solution for microwave treatment with the frequency of 800MHz, the power of 800W and the time of 5min, placing the diaphragm in clear water at the temperature of 60 ℃ after irradiation grafting treatment to wash away unreacted polyvinyl alcohol on the surface of the diaphragm, and drying to obtain the ultrathin high-strength modified lithium ion battery diaphragm.
Example 4
The preparation method of the ultrathin high-strength modified lithium ion battery diaphragm comprises the following steps:
(1) uniformly mixing 70 parts by weight of ultrahigh molecular weight polyethylene, 30 parts by weight of ultrahigh molecular weight polyethylene, 8 parts by weight of silane coupling modified fumed silica, 0.2 part by weight of antioxidant and 300 parts by weight of white oil to obtain a mixture;
(2) conveying the mixture to a screw extruder, carrying out melt extrusion at 220 ℃, obtaining a thick sheet by casting the sheet, longitudinally stretching the thick sheet by 14 times to obtain a sheet, transversely stretching the sheet by 11 times to obtain an oil-containing film, placing the oil-containing film in dichloromethane for extraction of white oil, drying the oil-containing film to obtain a dry film, transversely stretching the dry film by 1.2 times to obtain a microporous film, drawing the microporous film to pass through a hot roller at 100 ℃, shaping the microporous film by a cold roller below 30 ℃, and rolling and slitting the microporous film to obtain the ultrathin microporous diaphragm;
(3) placing the microporous diaphragm in a fluorination instrument which is preheated and then is introduced with nitrogen, introducing fluorine gas to 3kPa at normal temperature to perform fluorination reaction for 270s to obtain the fluorinated microporous diaphragm, firstly treating 8cm multiplied by 8cm of the fluorinated microporous diaphragm under a plasma beam with the current intensity of 15A for 1min, then placing the treated diaphragm in a polyvinyl alcohol solution with the current intensity of 100g and 15 wt% at 50 ℃ to perform stirring reaction for 5min, placing the diaphragm in clear water with the temperature of 60 ℃ to wash away unreacted polyvinyl alcohol on the surface of the diaphragm after irradiation grafting treatment, and drying to obtain the ultrathin high-strength modified lithium ion battery diaphragm.
Comparative example 1
The separator of this comparative example was a commercially available conventional 5 μm polyethylene separator.
Comparative example 2
The comparative example is the same as the preparation method of the example 1, except that the silane coupling modified fumed silica is not added.
Comparative example 3
This comparative example is the same as the preparation method of example 1 except that the step (3) is not subjected to the subsequent irradiation graft treatment.
The basic performance test of the separator was performed for the above examples and comparative examples, and the results are shown in table 1.
TABLE 1 basic Properties of the separator
As can be seen from Table 1, the modified membrane prepared by the method of the invention has higher puncture strength and tensile strength, lower heat shrinkage rate and better heat resistance under the condition that the membrane thickness is less than 4 μm, and has better mechanical properties compared with the common membrane (comparative example 1) with the thickness of 5 μm. Comparative example 2, to which no silica was added, was inferior in mechanical strength and heat resistance to those of example 1, indicating that silica has a reinforcing effect on the polyethylene base material and an effect of improving heat resistance. The mechanical properties of the separator of comparative example 3, which was not subjected to the subsequent irradiation graft modification, were not much different from those of example 1.
The separators of the above examples and comparative examples were used in lithium ion batteriesThe preparation method comprises the steps of independently using the raw materials to prepare a 2032 type button battery, using lithium cobaltate as a positive electrode, graphite as a negative electrode, and dissolving 1M LiPF in EC + DMC + DEC mixed solution with the volume of electrolyte being 1:1:1 6 . The separators of the above examples and comparative examples were disposed between the positive and negative electrodes. The cycle performance was then tested and the data is shown in table 2.
The liquid absorption rate test method of the diaphragm comprises the following steps: soaking a diaphragm in the electrolyte for 24 hours to enable the diaphragm to adsorb the electrolyte in a saturated mode, taking out the diaphragm, sucking the electrolyte on the surface of the diaphragm through filter paper, weighing the diaphragm before and after soaking, and respectively recording as W dry (dry film weight) and W wet (wet film weight) in accordance with (W) wet -W dry )÷W dry X 100 calculating the imbibition rate.
The liquid retention of the diaphragm is the retention rate of electrolyte in the diaphragm, and the test method comprises the following steps: placing the diaphragm saturated and adsorbing the electrolyte into a sample bag, taking out after 18h, measuring the mass, recording as Ws, and keeping the retention rate as% dry )÷(W wet -W dry )×100。
TABLE 2 separator applications and Performance in lithium batteries
Note: and (3) testing the specific capacity of the battery under the condition of cycle performance testing, namely testing the specific capacity of the battery after constant current charging and discharging for 200 times at 60 ℃ and 0.2C multiplying power.
After the microporous diaphragm is obtained, the surface of the microporous diaphragm is fluorinated through fluorination treatment, hydrogen atoms in the polyethylene matrix are replaced by fluorine atoms, so that the fluorinated polyethylene microporous diaphragm has certain polarity, and the fluorinated diaphragm (comparative example 3) also has good wettability and liquid absorption and retention properties. And then, carrying out irradiation grafting treatment on the fluorinated membrane and polyvinyl alcohol, combining fluorine atoms on the surface of the fluorinated polyethylene microporous membrane with hydrogen atoms on polyvinyl alcohol hydroxyl groups after irradiation to generate a part of hydrogen fluoride, grafting macromolecular chains of the polyvinyl alcohol to the surface of the microporous membrane, grafting the surface fluorine atoms into active points after the fluorination treatment, and grafting the macromolecular chains on fluorine active points through the irradiation treatment to obtain the modified membrane which has better wettability and liquid absorption and retention capacity on electrolyte, thereby improving the cycle performance and specific capacity of the lithium battery.
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 (6)
1. The preparation method of the ultrathin high-strength modified lithium ion battery diaphragm is characterized by comprising the following steps of:
(1) uniformly mixing 60-80 parts by weight of ultrahigh molecular weight polyethylene, 20-40 parts by weight of ultrahigh molecular weight polyethylene, 5-10 parts by weight of silane coupling modified fumed silica, 0.1-0.5 part by weight of antioxidant and 200-400 parts by weight of white oil to obtain a mixture;
(2) conveying the mixture to a screw extruder for melt extrusion, obtaining a thick sheet by casting, then carrying out biaxial tension treatment on the thick sheet, removing white oil, carrying out traction shaping, rolling and slitting to obtain a microporous diaphragm with the film thickness of less than 4 mu m;
(3) carrying out fluorination treatment on the microporous diaphragm to obtain a fluorinated microporous diaphragm, then carrying out irradiation grafting treatment, washing and drying to obtain an ultrathin high-strength modified lithium ion battery diaphragm;
the fluorination treatment process comprises the following steps: placing the microporous diaphragm in a fluorination instrument which is preheated and then is introduced with nitrogen, filling fluorine gas to 2-5 kPa at normal temperature to perform fluorination reaction for 30-270 s, and performing at least one time of fluorination treatment;
the irradiation grafting treatment is as follows: placing the fluorinated microporous membrane in a polyvinyl alcohol solution for microwave treatment, wherein the frequency of the microwave treatment is 800 MHz-1200 MHz, the power is 500W-800W, and the time is 2 min-5 min; or the fluorinated microporous membrane is firstly subjected to plasma beam treatment, and then the treated membrane is placed in a polyvinyl alcohol solution at the temperature of 50-80 ℃ to be stirred and react for 2-5 min, wherein the current intensity of the plasma beam treatment is 10-15A, and the time is 1-3 min; the mass concentration of the polyvinyl alcohol solution is 5-30%;
the prepared ultrathin high-strength modified lithium ion battery diaphragm is grafted on the surface of a polyethylene diaphragm
The thickness of the group is less than 4 μm, and the ultrathin high-strength modified lithium ion battery separator can be used alone as a separator or can be used in combination with other separators with different thicknesses.
2. The method for preparing the ultrathin high-strength modified lithium ion battery separator according to claim 1, wherein the temperature of the melt extrusion in the step (2) is 180-240 ℃.
3. The method for preparing the ultrathin high-strength modified lithium ion battery separator according to claim 1, wherein the biaxial stretching treatment in the step (2) is to longitudinally stretch the thick sheet by 7 to 15 times and then transversely stretch the thick sheet by 7 to 15 times.
4. The method for preparing the ultrathin high-strength modified lithium ion battery separator according to claim 1, wherein the white oil removing process in the step (2) is as follows: the biaxially oriented film was placed in methylene chloride to extract white oil.
5. The method for preparing the ultrathin high-strength modified lithium ion battery separator according to claim 1, wherein the step (2) further comprises performing a second transverse stretching by 1.1 to 2 times after the white oil is removed.
6. The method for preparing the ultrathin high-strength modified lithium ion battery separator as claimed in claim 1, wherein the drawing and shaping process in the step (2) is to pass the film through a hot roller at 40-120 ℃ and a cold roller below 40 ℃ by drawing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011241175.3A CN112332023B (en) | 2020-11-09 | 2020-11-09 | Ultrathin high-strength modified lithium ion battery diaphragm and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011241175.3A CN112332023B (en) | 2020-11-09 | 2020-11-09 | Ultrathin high-strength modified lithium ion battery diaphragm and preparation method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112332023A CN112332023A (en) | 2021-02-05 |
| CN112332023B true CN112332023B (en) | 2022-08-05 |
Family
ID=74315613
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011241175.3A Active CN112332023B (en) | 2020-11-09 | 2020-11-09 | Ultrathin high-strength modified lithium ion battery diaphragm and preparation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112332023B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113140864B (en) * | 2021-03-04 | 2022-12-23 | 乐凯胶片股份有限公司 | Diaphragm and preparation method and application thereof |
| CN112864528B (en) * | 2021-04-26 | 2021-07-13 | 江苏厚生新能源科技有限公司 | Biaxial tension coating microporous diaphragm for lithium ion battery and preparation method thereof |
| CN114597589B (en) * | 2022-05-11 | 2022-08-05 | 北京化工大学 | Wet-process high-strength lithium battery diaphragm and preparation method thereof |
| WO2024011364A1 (en) * | 2022-07-11 | 2024-01-18 | 宁德时代新能源科技股份有限公司 | Polyolefin-based film and preparation method therefor, separator, secondary battery and electrical apparatus |
| CN115674628B (en) * | 2022-12-30 | 2023-05-02 | 四川卓勤新材料科技有限公司 | Polyethylene ultra-thin film and preparation method thereof |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102751460A (en) * | 2012-05-23 | 2012-10-24 | 杭州福膜新材料科技有限公司 | High-temperature-resisting composite isolation film and preparation method thereof |
| CN106920912A (en) * | 2017-04-14 | 2017-07-04 | 上海恩捷新材料科技股份有限公司 | A kind of preparation method of lithium ion battery barrier film |
| CN108550769A (en) * | 2018-05-21 | 2018-09-18 | 珠海光宇电池有限公司 | The preparation method and lithium ion battery of lithium ion battery separator |
| CN111755650A (en) * | 2020-06-05 | 2020-10-09 | 江苏厚生新能源科技有限公司 | Preparation method of lithium battery diaphragm modified by ultraviolet radiation grafting, lithium battery diaphragm and application of lithium battery diaphragm |
-
2020
- 2020-11-09 CN CN202011241175.3A patent/CN112332023B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102751460A (en) * | 2012-05-23 | 2012-10-24 | 杭州福膜新材料科技有限公司 | High-temperature-resisting composite isolation film and preparation method thereof |
| CN106920912A (en) * | 2017-04-14 | 2017-07-04 | 上海恩捷新材料科技股份有限公司 | A kind of preparation method of lithium ion battery barrier film |
| CN108550769A (en) * | 2018-05-21 | 2018-09-18 | 珠海光宇电池有限公司 | The preparation method and lithium ion battery of lithium ion battery separator |
| CN111755650A (en) * | 2020-06-05 | 2020-10-09 | 江苏厚生新能源科技有限公司 | Preparation method of lithium battery diaphragm modified by ultraviolet radiation grafting, lithium battery diaphragm and application of lithium battery diaphragm |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112332023A (en) | 2021-02-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112332023B (en) | Ultrathin high-strength modified lithium ion battery diaphragm and preparation method thereof | |
| Li et al. | Development of plasma-treated polypropylene nonwoven-based composites for high-performance lithium-ion battery separators | |
| JP5280313B2 (en) | Lithium ion polymer battery comprising a polyolefin microporous membrane surface-modified with a hydrophilic polymer, a surface modification method thereof, and a surface-modified polyolefin microporous membrane as a separator | |
| CN102888016B (en) | Preparation method of lithium-ion secondary battery diaphragm with crosslinking composite layer | |
| Li et al. | Effects of fluorinated SiO2 nanoparticles on the thermal and electrochemical properties of PP nonwoven/PVdF-HFP composite separator for Li-ion batteries | |
| Guo et al. | Thermally stable and green cellulose-based composites strengthened by styrene-co-acrylate latex for lithium-ion battery separators | |
| Wei et al. | Cross-linked porous polymer separator using vinyl-modified aluminum oxide nanoparticles as cross-linker for lithium-ion batteries | |
| Lin et al. | Mechanically robust, nonflammable and surface cross-linking composite membranes with high wettability for dendrite-proof and high-safety lithium-ion batteries | |
| KR102248232B1 (en) | Separator, lithium secondary battery comprising the seperator and manufacturing method thereof | |
| EP3594278B1 (en) | Polyolefin microporous film | |
| KR20150059621A (en) | Composition for coating separator, separator formed by using the composition, and battery using the separator | |
| CN114696036B (en) | Transition metal capture diaphragm and preparation method and application thereof | |
| Jiang et al. | Modified polypropylene/cotton fiber composite nonwoven as lithium-ion battery separator | |
| CN116387606B (en) | All-solid-state battery pole piece, preparation method thereof, all-solid-state battery and electric device | |
| Xie et al. | The high performance of polydopamine-coated electrospun poly (ether sulfone) nanofibrous separator for lithium-ion batteries | |
| Liu et al. | Electrospun Silsequioxane-grafted PVDF hybrid membranes for high-performance rechargeable lithium batteries | |
| CN111755650A (en) | Preparation method of lithium battery diaphragm modified by ultraviolet radiation grafting, lithium battery diaphragm and application of lithium battery diaphragm | |
| CN114400372B (en) | Preparation method of solid electrolyte film of anisotropic ion transmission channel | |
| Song et al. | Electrospun PU/PVP/GO separator for Li-ion batteries | |
| CN113764823B (en) | High-performance gradient composite gel polymer diaphragm and preparation method thereof | |
| Miao et al. | Superior thermal stability of PVA/cellulose composite membranes for lithium-ion battery separators prepared by impregnation method with noncovalent cross-linking of intermolecular multiple hydrogen-bonds | |
| CN116014360A (en) | Composite diaphragm and preparation method and application thereof | |
| Xu et al. | Chemically modified polyvinyl butyral polymer membrane as a gel electrolyte for lithium ion battery applications | |
| JP7160621B2 (en) | Trace metal cross-linked separator | |
| CN112582750B (en) | Process for preparing high-performance lithium battery diaphragm by using polyethylene graft copolymer |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20231127 Address after: No. 369 Jinxiu Street, Yangqu Industrial Park, Shanxi Transformation and Comprehensive Reform Demonstration Zone, Taiyuan City, Shanxi Province, 030100 Patentee after: Shanxi Housheng New Material Technology Co.,Ltd. Address before: No.111 Huaye Road, Jintan District, Changzhou City, Jiangsu Province 213200 Patentee before: Jiangsu Housheng New Energy Technology Co.,Ltd. |