CN113451707A - Polyolefin diaphragm and preparation method thereof - Google Patents
Polyolefin diaphragm and preparation method thereof Download PDFInfo
- Publication number
- CN113451707A CN113451707A CN202010224948.0A CN202010224948A CN113451707A CN 113451707 A CN113451707 A CN 113451707A CN 202010224948 A CN202010224948 A CN 202010224948A CN 113451707 A CN113451707 A CN 113451707A
- Authority
- CN
- China
- Prior art keywords
- polyolefin
- pvdf
- oil
- plasticizer
- diaphragm
- 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.)
- Pending
Links
- 229920000098 polyolefin Polymers 0.000 title claims abstract description 97
- 238000002360 preparation method Methods 0.000 title description 9
- 239000002033 PVDF binder Substances 0.000 claims abstract description 74
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims abstract description 74
- 239000004014 plasticizer Substances 0.000 claims abstract description 47
- 238000001816 cooling Methods 0.000 claims description 29
- 239000003921 oil Substances 0.000 claims description 28
- 235000019198 oils Nutrition 0.000 claims description 28
- 239000007788 liquid Substances 0.000 claims description 24
- 239000006185 dispersion Substances 0.000 claims description 20
- 239000008240 homogeneous mixture Substances 0.000 claims description 18
- 238000000605 extraction Methods 0.000 claims description 17
- 239000002994 raw material Substances 0.000 claims description 17
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 claims description 15
- 238000002156 mixing Methods 0.000 claims description 14
- 239000000758 substrate Substances 0.000 claims description 14
- 230000002457 bidirectional effect Effects 0.000 claims description 9
- 238000009998 heat setting Methods 0.000 claims description 9
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 8
- DOIRQSBPFJWKBE-UHFFFAOYSA-N dibutyl phthalate Chemical compound CCCCOC(=O)C1=CC=CC=C1C(=O)OCCCC DOIRQSBPFJWKBE-UHFFFAOYSA-N 0.000 claims description 8
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims description 8
- BQCIDUSAKPWEOX-UHFFFAOYSA-N 1,1-Difluoroethene Chemical compound FC(F)=C BQCIDUSAKPWEOX-UHFFFAOYSA-N 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 7
- 238000005096 rolling process Methods 0.000 claims description 7
- 238000003756 stirring Methods 0.000 claims description 7
- 238000005303 weighing Methods 0.000 claims description 7
- 229920001577 copolymer Polymers 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 6
- 239000005662 Paraffin oil Substances 0.000 claims description 4
- 229920001519 homopolymer Polymers 0.000 claims description 4
- 239000003208 petroleum Substances 0.000 claims description 4
- NDMMKOCNFSTXRU-UHFFFAOYSA-N 1,1,2,3,3-pentafluoroprop-1-ene Chemical compound FC(F)C(F)=C(F)F NDMMKOCNFSTXRU-UHFFFAOYSA-N 0.000 claims description 3
- PGJHURKAWUJHLJ-UHFFFAOYSA-N 1,1,2,3-tetrafluoroprop-1-ene Chemical compound FCC(F)=C(F)F PGJHURKAWUJHLJ-UHFFFAOYSA-N 0.000 claims description 3
- MIZLGWKEZAPEFJ-UHFFFAOYSA-N 1,1,2-trifluoroethene Chemical group FC=C(F)F MIZLGWKEZAPEFJ-UHFFFAOYSA-N 0.000 claims description 3
- FDMFUZHCIRHGRG-UHFFFAOYSA-N 3,3,3-trifluoroprop-1-ene Chemical compound FC(F)(F)C=C FDMFUZHCIRHGRG-UHFFFAOYSA-N 0.000 claims description 3
- HCDGVLDPFQMKDK-UHFFFAOYSA-N hexafluoropropylene Chemical group FC(F)=C(F)C(F)(F)F HCDGVLDPFQMKDK-UHFFFAOYSA-N 0.000 claims description 3
- 235000010446 mineral oil Nutrition 0.000 claims description 3
- 239000002480 mineral oil Substances 0.000 claims description 3
- 235000012424 soybean oil Nutrition 0.000 claims description 3
- 239000003549 soybean oil Substances 0.000 claims description 3
- BFKJFAAPBSQJPD-UHFFFAOYSA-N tetrafluoroethene Chemical group FC(F)=C(F)F BFKJFAAPBSQJPD-UHFFFAOYSA-N 0.000 claims description 3
- 238000001132 ultrasonic dispersion Methods 0.000 claims description 3
- 239000001993 wax Substances 0.000 claims description 3
- 239000003792 electrolyte Substances 0.000 abstract description 17
- 230000014759 maintenance of location Effects 0.000 abstract description 5
- 239000000203 mixture Substances 0.000 description 9
- 238000009792 diffusion process Methods 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- 239000012528 membrane Substances 0.000 description 6
- 238000013329 compounding Methods 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000001360 synchronised effect Effects 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000009194 climbing Effects 0.000 description 1
- 239000013065 commercial product Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 229910001416 lithium ion Inorganic materials 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
- 230000037303 wrinkles Effects 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/001—Combinations of extrusion moulding with other shaping operations
- B29C48/0018—Combinations of extrusion moulding with other shaping operations combined with shaping by orienting, stretching or shrinking, e.g. film blowing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/022—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the choice of material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
- B29C48/07—Flat, e.g. panels
- B29C48/08—Flat, e.g. panels flexible, e.g. films
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C71/00—After-treatment of articles without altering their shape; Apparatus therefor
- B29C71/0009—After-treatment of articles without altering their shape; Apparatus therefor using liquids, e.g. solvents, swelling agents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C71/00—After-treatment of articles without altering their shape; Apparatus therefor
- B29C71/0009—After-treatment of articles without altering their shape; Apparatus therefor using liquids, e.g. solvents, swelling agents
- B29C2071/0027—Removing undesirable residual components, e.g. solvents, unreacted monomers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
- B29K2027/12—Use of polyvinylhalogenides or derivatives thereof as moulding material containing fluorine
- B29K2027/16—PVDF, i.e. polyvinylidene fluoride
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Cell Separators (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
The invention discloses a polyolefin diaphragm, which is prepared from PVDF, polyolefin and a plasticizer, wherein the content of the PVDF in the polyolefin diaphragm is 0.1-12% of the surface of the polyolefin diaphragm. The polyolefin diaphragm prepared by the invention has the advantages that PVDF is uniformly distributed in the diaphragm and on the surface of the diaphragm, and the diaphragm has better electrolyte wettability and higher electrolyte retention rate.
Description
Technical Field
The invention relates to the field of biology, in particular to a polyolefin diaphragm and a preparation method thereof.
Background
The diaphragm is used as an important component of the lithium battery and is positioned between the anode and the cathode of the battery, so that the anode and the cathode of the battery are separated, the internal short circuit of the battery is prevented, and lithium ions in the electrolyte are allowed to freely pass through the diaphragm, thereby ensuring the charging and discharging of the battery. The polyolefin diaphragm is one of commercialized diaphragm materials due to the advantages of high strength, good acid and alkali resistance, good solvent performance, good electrochemical stability and the like. However, the polyolefin diaphragm has poor electrolyte wettability and low electrolyte retention rate, and in the process of battery assembly, if the diaphragm is not fully wetted by electrolyte, the diaphragm at the part which is not fully wetted is easy to wrinkle, and the risk of battery short circuit exists in the later period; in addition, in the charging and discharging process of the battery, heat can be generated, so that the electrolyte is more easily volatilized, the cycle life of the battery is greatly shortened, and even explosion can be caused in severe cases, so that the life safety of a user is threatened.
Disclosure of Invention
In order to overcome the disadvantages of the prior art, the present invention is directed to providing a polyolefin separator having superior electrolyte wettability and superior electrolyte retention.
In order to solve the problems, the technical scheme adopted by the invention is as follows:
a polyolefin diaphragm is prepared from PVDF, polyolefin and a plasticizer, wherein the content of the PVDF in the interior and the surface of the polyolefin diaphragm is 0.1-12%.
Preferably, the composition is prepared from the following raw materials in percentage by weight:
PVDF 0.1-12％，
15 to 40 percent of polyolefin,
plasticizers, and others.
Preferably, the composition is prepared from the following raw materials in percentage by weight:
PVDF 0.6％，
19.4 percent of polyolefin,
80% of plasticizer.
Preferably, the composition is prepared from the following raw materials in percentage by weight:
PVDF 1.75％，
23.25 percent of polyolefin,
75% of plasticizer.
Preferably, the composition is prepared from the following raw materials in percentage by weight:
PVDF 4.5％，
25.5 percent of polyolefin,
70% of plasticizer.
Preferably, the composition is prepared from the following raw materials in percentage by weight:
PVDF 12％，
28 percent of polyolefin,
60% of plasticizer.
The PVDF content is too low, the wetting effect is poor, and the PVDF content is too high, so that the appearance and the performance of the diaphragm are influenced. Too high polyolefin proportion leads to the increase of overall mixing viscosity, too large extrusion pressure and difficult processing, and too small polyolefin proportion leads to uneven mixing and unobvious shearing effect.
Preferably, the PVDF is a vinylidene fluoride homopolymer or a vinylidene fluoride copolymer, and the vinylidene fluoride copolymer is prepared by copolymerizing vinylidene fluoride and one or more of hexafluoropropylene, pentafluoropropene, tetrafluoropropene, trifluoropropene, trifluoroethylene and tetrafluoroethylene.
Preferably, the particle size of the PVDF is 0.01-10 μm. The particle size is too large, the particles are not easy to be completely melted during mixing, and the particles are too small and easy to agglomerate.
Preferably, the polyolefin has a molecular weight of 1.0X 105-3.0×106. If the molecular weight is too low, the performance of the diaphragm is poor, and if the molecular weight is too high, the diaphragm is not easy to stretch, even stretching, unclamping and cracking occur.
Preferably, the plasticizer is one or more of paraffin oil, mineral oil, soybean oil, wax and dibutyl phthalate. The plasticizer is mainly used for forming a microporous structure of the separator and has a lubricating effect when being mixed with PVDF and polyolefin.
The invention also comprises a preparation method of the polyolefin diaphragm, which comprises the following steps:
s101, accurately weighing each component, and dividing plasticizers into two groups;
s102, putting PVDF into a group of plasticizers, stirring and ultrasonically dispersing to obtain a PVDF dispersion liquid;
s103, adding the PVDF dispersion liquid, the polyolefin and the other group of plasticizer into a double-screw extruder at 220 ℃, mixing for 5-25min to obtain a homogeneous mixture, extruding the homogeneous mixture through a die head lip, and cooling on a cooling roller to obtain an oil-containing substrate;
s104, carrying out bidirectional 5-9 times stretching on the oil-containing substrate at the temperature of 110-135 ℃ to obtain an oil-containing film, and extracting the oil-containing film in an extraction tank to obtain an oil-free film;
s105, carrying out heat setting on the oil-free film at the temperature of 120-150 ℃ for 1-5min, and rolling to obtain the polyolefin diaphragm.
The mixing temperature is 170-220 ℃, the temperature is too low, so that PVDF and polyolefin are not completely melted, the mixing is not uniform, and the temperature is too high, so that the polyolefin is preferentially degraded. The mixing time is 5-25min, the time is too short, so that PVDF and polyolefin are not completely melted, the mixing is not uniform, the time is too long, and the polyolefin is preferentially degraded. The stretching film forming is bidirectional synchronous stretching, the stretching temperature is 110-135 ℃, the bidirectional synchronous stretching is mainly used for ensuring the uniformity of the film, the stretching temperature is too low, the stretching is not uniform or even can not be carried out, and the film is easy to stretch and break when the stretching temperature is too high; in the stretching multiplying power, the MD direction is between 5 and 9 times, the TD direction is between 5 and 9 times, the stretching multiplying power directly influences the film forming performance, the multiplying power is too low, the diaphragm performance is poor, the internal stress of the diaphragm is increased due to too high multiplying power, the shrinkage is increased, and even the stretching rupture occurs. The heat setting temperature is between 120 and 150 ℃, and the heat setting is mainly used for eliminating internal stress and improving the performance of the diaphragm; if the temperature is too low, internal stress is eliminated too little, and if the temperature is too high, closed pores are caused, and the film forming performance is influenced.
Further, in the step S102, the ultrasonic dispersion time is 10-60min, so as to ensure uniform dispersion.
Further, in the step S102, the PVDF dispersion liquid has a weight percentage of 1-30%. Too high a proportion, difficult dispersion, too low a proportion, increase in equipment cost and deterioration in dispersion efficiency.
Further, in step S103, the cooling rate of the cast sheet on the cooling roll is 0-30 ℃/S, and an excessive cooling rate may cause a large difference between the crystallization rates of PVDF and polyolefin, resulting in severe separation of two phases.
Further, in the step S104, the extraction liquid in the extraction tank is one or more of n-hexane, dichloromethane and petroleum ether. The extractant can displace the plasticizer from the membrane, and then volatilize to make the membrane pore-forming.
Compared with the prior art, the invention has the beneficial effects that: the production process is simple, and the PVDF of the prepared polyolefin diaphragm is uniformly distributed in the diaphragm and on the surface of the diaphragm, so that the diaphragm has better electrolyte wettability and higher electrolyte retention rate.
Drawings
FIG. 1 is an SEM photograph of a random spot on a commercial product M-0;
FIG. 2 is an SEM photograph of a random one place on the polyolefin separator M-1 in example 1;
FIG. 3 is an SEM photograph of a random one place on the polyolefin separator M-2 in example 2;
FIG. 4 is an SEM photograph of a random one place on the polyolefin separator M-3 in example 3;
FIG. 5 is an SEM photograph of a random one place on the polyolefin separator M-4 in example 4;
FIG. 6 is an EDS plot of polyolefin membrane M-2 at random first points in example 2;
FIG. 7 is an EDS plot of the polyolefin membrane M-2 at a random second point in example 2;
FIG. 8 is an EDS plot of polyolefin separator M-2 at a random third point in example 2;
FIG. 9 is a graph showing the diffusion area of a commercially available product M-0;
FIG. 10 is a graph showing the diffusion area of the polyolefin separator M-2 in example 2.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments.
The invention relates to a polyolefin diaphragm, which is prepared from PVDF, polyolefin and a plasticizer, wherein the content of PVDF in the interior and the surface of the polyolefin diaphragm is 0.1-12%.
Preferably, the polyolefin diaphragm is prepared from the following raw materials in percentage by weight: 0.1-12% of PVDF, 15-40% of polyolefin and the balance plasticizer. Preferably, the composition is prepared from the following raw materials in percentage by weight: 0.6% PVDF, 19.4% polyolefin and 80% plasticizer. Preferably, the composition is prepared from the following raw materials in percentage by weight: 1.75% PVDF, 23.25% polyolefin, 75% plasticizer. Preferably, the composition is prepared from the following raw materials in percentage by weight: 4.5% PVDF, 25.5% polyolefin, 70% plasticizer. Preferably, the composition is prepared from the following raw materials in percentage by weight: 12% PVDF, 28% polyolefin, 60% plasticizer.
Preferably, the PVDF is a vinylidene fluoride homopolymer or a vinylidene fluoride copolymer, and the vinylidene fluoride copolymer is prepared by copolymerizing vinylidene fluoride and one or more of hexafluoropropylene, pentafluoropropene, tetrafluoropropene, trifluoropropene, trifluoroethylene and tetrafluoroethylene. The particle size of the PVDF is 0.01-10 mu m. The polyolefin has a molecular weight of 1.0X 105-3.0×106. The plasticizer is one or more of paraffin oil, mineral oil, soybean oil, wax and dibutyl phthalate.
The invention also comprises a preparation method of the polyolefin diaphragm, which comprises the following steps:
s101, accurately weighing each component, and dividing plasticizers into two groups;
s102, putting PVDF into a group of plasticizers, stirring and ultrasonically dispersing to obtain a PVDF dispersion liquid;
s103, adding the PVDF dispersion liquid, the polyolefin and the other group of plasticizer into a double-screw extruder at 220 ℃, mixing for 5-25min to obtain a homogeneous mixture, extruding the homogeneous mixture through a die head lip, and cooling on a cooling roller to obtain an oil-containing substrate;
s104, carrying out bidirectional 5-9 times stretching on the oil-containing substrate at the temperature of 110-135 ℃ to obtain an oil-containing film, and extracting the oil-containing film in an extraction tank to obtain an oil-free film;
s105, carrying out heat setting on the oil-free film at the temperature of 120-150 ℃ for 1-5min, and rolling to obtain the polyolefin diaphragm.
Further, in the step S102, the ultrasonic dispersion time is 10 to 60 min. In the step S102, the PVDF is present in the PVDF dispersion liquid in an amount of 1 to 30% by weight. In step S103, the cooling rate of the cast sheet on the cooling roll is 0-30 ℃/S. In the step S104, the extraction liquid in the extraction tank is one or more of n-hexane, dichloromethane and petroleum ether.
Example 1
Preparation of polyolefin separator M-1
TABLE 1 polyolefin separator M-1 compounding Table (Total solids 20%, PVDF 3% therein)
S101, accurately weighing the components according to the table 1, and dividing the plasticizer into two groups;
s102, putting PVDF into a group of plasticizers, stirring and ultrasonically dispersing for 60min to obtain PVDF dispersion liquid, wherein the weight percentage of the PVDF is 4%;
s103, adding the PVDF dispersion liquid, the polyolefin and the other group of plasticizer into a 220 ℃ double-screw extruder together, mixing for 20min to obtain a homogeneous mixture, extruding the homogeneous mixture through a die head lip, cooling the homogeneous mixture on a cooling roller to form an oil-containing substrate, wherein the cooling rate of a cast sheet on the cooling roller is 30 ℃/s;
s104, carrying out bidirectional stretching on an oil-containing substrate at 115 ℃, wherein the stretching ratio MD is 8 times, and the TD is 8 times, so as to obtain an oil-containing film, extracting the oil-containing film in an extraction tank, so as to obtain an oil-free film, and extracting solution in the extraction tank is dichloromethane;
and S105, carrying out heat setting on the oil-free film at 135 ℃ for 1min, and rolling to obtain the polyolefin diaphragm M-1.
Example 2
Preparation of polyolefin separator M-2
TABLE 2 polyolefin separator M-2 compounding Table (total solid content 25%, 7% of PVDF)
| Raw materials | Name (R) | Content (kg) |
| PVDF | Vinylidene fluoride homopolymer | 7 |
| Polyolefins | Polyolefin (molecular weight 6.0X 10)5) | 93 |
| Plasticizer agent | Dibutyl phthalate | 300 |
S201, accurately weighing the components according to the table 2, and dividing the plasticizer into two groups;
s202, putting PVDF into a group of plasticizers, stirring and ultrasonically dispersing for 30min to obtain PVDF dispersion liquid, wherein the weight percentage of the PVDF is 5%;
s203, adding the PVDF dispersion liquid, the polyolefin and the other group of plasticizer into a double-screw extruder at 190 ℃, mixing for 15min to obtain a homogeneous mixture, extruding the homogeneous mixture through a die head lip, cooling the homogeneous mixture on a cooling roller to form an oil-containing substrate, wherein the cooling rate of a cast sheet on the cooling roller is 20 ℃/s;
s204, carrying out bidirectional stretching on an oil-containing substrate at 125 ℃, wherein the stretching ratio MD is 7 times, and the TD is 7 times, so as to obtain an oil-containing film, extracting the oil-containing film in an extraction tank, so as to obtain an oil-free film, and extracting solution in the extraction tank is dichloromethane;
s205, carrying out heat setting on the oil-free film at 135 ℃ for 1min, and rolling to obtain the polyolefin diaphragm M-2.
Example 3
Preparation of polyolefin separator M-3
TABLE 3 polyolefin membrane M-3 compounding Table (total solid content 30%, 15% of PVDF)
| Raw materials | Name (R) | Content (kg) |
| PVDF | Vinylidene fluoride-hexafluoropropylene copolymer | 18 |
| Polyolefins | Polyolefin (molecular weight 1.5X 10)5) | 102 |
| Plasticizer agent | Paraffin oil | 280 |
S301, accurately weighing the components according to the table 3, and dividing the plasticizer into two groups;
s302, putting PVDF into a group of plasticizers, stirring and ultrasonically dispersing for 15min to obtain PVDF dispersion liquid, wherein the weight percentage of the PVDF is 12%;
s303, adding the PVDF dispersion liquid, the polyolefin and the other group of plasticizer into a 180-DEG C double-screw extruder, mixing for 25min to obtain a homogeneous mixture, extruding the homogeneous mixture through a die head lip, cooling the homogeneous mixture on a cooling roller to form an oil-containing substrate, wherein the cooling rate of a cast sheet on the cooling roller is 15 ℃/s;
s304, carrying out bidirectional stretching on an oil-containing substrate at 110 ℃, wherein the stretching ratio MD is 6 times, and the TD is 6 times, so as to obtain an oil-containing film, extracting the oil-containing film in an extraction tank, so as to obtain an oil-free film, and extracting solution in the extraction tank is n-hexane;
s305, carrying out heat setting on the oil-free film at 125 ℃ for 2min, and rolling to obtain the polyolefin diaphragm M-3.
Example 4
Preparation of polyolefin separator M-4
TABLE 4 polyolefin separator M-4 compounding Table (Total solid content 40%, with PVDF 30%)
S401, accurately weighing the components according to the table 4, and dividing the plasticizer into two groups;
s402, putting PVDF into a group of plasticizers, stirring and ultrasonically dispersing for 40min to obtain a PVDF dispersion liquid, wherein the weight percentage of the PVDF is 30%;
s403, adding the PVDF dispersion liquid, the polyolefin and the other group of plasticizer into a 200-DEG C double-screw extruder, mixing for 15min to obtain a homogeneous mixture, extruding the homogeneous mixture through a die head lip, cooling the homogeneous mixture on a cooling roller to form an oil-containing substrate, wherein the cooling rate of a cast sheet on the cooling roller is 25 ℃/s;
s404, carrying out bidirectional stretching on an oil-containing substrate at 130 ℃, wherein the stretching ratio MD is 8 times, and the TD is 8 times, so as to obtain an oil-containing film, extracting the oil-containing film in an extraction tank, so as to obtain an oil-free film, and extracting liquid in the extraction tank is petroleum ether;
s405, carrying out heat setting on the oil-free film at 140 ℃ for 1min, and rolling to obtain the polyolefin diaphragm M-4.
Example 5 detection experiment
Commercially available separator products M-0 and polyolefin separators M-1 to M-4 obtained in examples 1 to 4 were sampled, respectively, and subjected to EDS inspection on the surfaces and sections thereof, which are denoted in order by X0, X1, X2, X3, X4, and the sections are denoted in order by Y0, Y1, Y2, Y3, and Y4.
The test method is as follows:
surface testing: SEM and EDS tests are carried out on the surface of the sample by using an electron microscope.
And (3) section testing: the membrane is placed in liquid nitrogen for 20min, then broken off, and SEM and EDS tests are carried out on the section of the sample by using a microscope.
The SEM pictures of M-0 to M-4 shown in Table 5 below and in FIGS. 1 to 5, and the EDS pictures of M-2 shown in FIGS. 6 to 8 (three random points in cross section) were obtained.
| Sampling | X0 | X1 | X2 | X3 | X4 | Y0 | Y1 | Y2 | Y3 | Y4 |
| Content of F/%) | 0 | 1.2 | 2.6 | 5.4 | 10.1 | 0 | 1.1 | 2.5 | 5.2 | 10.0 |
Commercially available separator product M-0 and polyolefin separators M-1 to M-4 prepared in examples 1 to 4 were sampled respectively for liquid absorption height and diffusion area tests as follows:
liquid absorption height test: and (3) immersing the diaphragm with the width of 10mm into the electrolyte, standing for 5min, and measuring the climbing height of the electrolyte, namely the imbibing height.
And (3) testing the diffusion area: 0.02ml of electrolyte is dropped on a diaphragm with the thickness of 10cmx10cm, and the area soaked by the electrolyte after 1min is measured, namely the diffusion area.
The diffusion area plots for M-0 and M-2 are obtained as shown in Table 6 below and in FIGS. 9-10.
As can be seen from fig. 1 to 10 and tables 5 and 6 above, in the polyolefin separator prepared according to the embodiment of the present invention, PVDF is uniformly distributed inside and on the surface of the separator, so that both the liquid absorption height and the diffusion area of the separator are significantly improved, and the separator has good electrolyte wettability and high electrolyte retention rate.
Various other modifications and changes may be made by those skilled in the art based on the above-described technical solutions and concepts, and all such modifications and changes should fall within the scope of the claims of the present invention.
Claims (15)
1. The polyolefin diaphragm is characterized by being prepared from PVDF, polyolefin and plasticizer, wherein the content of PVDF in the interior and the surface of the polyolefin diaphragm is 0.1-12%.
2. The polyolefin separator of claim 1, characterized by being prepared from the following raw materials in percentage by weight:
PVDF 0.1-12％，
15 to 40 percent of polyolefin,
plasticizers, and others.
3. The polyolefin separator of claim 2, characterized by being prepared from the following raw materials in percentage by weight:
PVDF 0.6％，
19.4 percent of polyolefin,
80% of plasticizer.
4. The polyolefin separator of claim 2, characterized by being prepared from the following raw materials in percentage by weight:
PVDF 1.75％，
23.25 percent of polyolefin,
75% of plasticizer.
5. The polyolefin separator of claim 2, characterized by being prepared from the following raw materials in percentage by weight:
PVDF 4.5％，
25.5 percent of polyolefin,
70% of plasticizer.
6. The polyolefin separator of claim 2, characterized by being prepared from the following raw materials in percentage by weight:
PVDF 12％，
28 percent of polyolefin,
60% of plasticizer.
7. The polyolefin separator of claim 1, wherein said PVDF is a vinylidene fluoride homopolymer or a vinylidene fluoride copolymer copolymerized from vinylidene fluoride and one or more of hexafluoropropylene, pentafluoropropene, tetrafluoropropene, trifluoropropene, trifluoroethylene, and tetrafluoroethylene.
8. The polyolefin separator of claim 1, wherein said PVDF particle size is 0.01-10 μ ι η.
9. The polyolefin separator of claim 1, wherein said polyolefin has a molecular weight of 1.0 x105-3.0×106。
10. The polyolefin separator of claim 1, wherein said plasticizer is one or more of paraffin oil, mineral oil, soybean oil, wax, and dibutyl phthalate.
11. A method for preparing the polyolefin separator of any one of claims 1 to 10, comprising the steps of:
s101, accurately weighing each component, and dividing plasticizers into two groups;
s102, putting PVDF into a group of plasticizers, stirring and ultrasonically dispersing to obtain a PVDF dispersion liquid;
s103, adding the PVDF dispersion liquid, the polyolefin and the other group of plasticizer into a double-screw extruder at 220 ℃, mixing for 5-25min to obtain a homogeneous mixture, extruding the homogeneous mixture through a die head lip, and cooling on a cooling roller to obtain an oil-containing substrate;
s104, carrying out bidirectional 5-9 times stretching on the oil-containing substrate at the temperature of 110-135 ℃ to obtain an oil-containing film, and extracting the oil-containing film in an extraction tank to obtain an oil-free film;
s105, carrying out heat setting on the oil-free film at the temperature of 120-150 ℃ for 1-5min, and rolling to obtain the polyolefin diaphragm.
12. The method of claim 11, wherein in step S102, the ultrasonic dispersion time is 10-60 min.
13. The method of claim 11, wherein in step S102, the PVDF dispersion has a PVDF content of 1-30 wt%.
14. The method of claim 11, wherein the cooling rate of the cast slab on the cooling roll in the step S103 is 0 to 30 ℃/S.
15. The method of claim 11, wherein in step S104, the extraction liquid in the extraction tank is one or more of n-hexane, dichloromethane and petroleum ether.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010224948.0A CN113451707A (en) | 2020-03-26 | 2020-03-26 | Polyolefin diaphragm and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010224948.0A CN113451707A (en) | 2020-03-26 | 2020-03-26 | Polyolefin diaphragm and preparation method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113451707A true CN113451707A (en) | 2021-09-28 |
Family
ID=77807614
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010224948.0A Pending CN113451707A (en) | 2020-03-26 | 2020-03-26 | Polyolefin diaphragm and preparation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113451707A (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1554695A (en) * | 2003-12-24 | 2004-12-15 | 中国科学院广州化学研究所 | Process for preparing polymer diaphragm for lithium ion cell |
| CN103199210A (en) * | 2013-04-22 | 2013-07-10 | 上海双奥能源技术有限公司 | Lithium ion battery diaphragm |
| CN103682218A (en) * | 2013-12-23 | 2014-03-26 | 中国科学院上海硅酸盐研究所 | Organic-inorganic composite lithium ion battery diaphragm and preparation method thereof |
| CN105514321A (en) * | 2015-12-14 | 2016-04-20 | 苏州锂盾储能材料技术有限公司 | High efficiency diaphragm material of lithium ion battery and preparation method of diaphragm material |
-
2020
- 2020-03-26 CN CN202010224948.0A patent/CN113451707A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1554695A (en) * | 2003-12-24 | 2004-12-15 | 中国科学院广州化学研究所 | Process for preparing polymer diaphragm for lithium ion cell |
| CN103199210A (en) * | 2013-04-22 | 2013-07-10 | 上海双奥能源技术有限公司 | Lithium ion battery diaphragm |
| CN103682218A (en) * | 2013-12-23 | 2014-03-26 | 中国科学院上海硅酸盐研究所 | Organic-inorganic composite lithium ion battery diaphragm and preparation method thereof |
| CN105514321A (en) * | 2015-12-14 | 2016-04-20 | 苏州锂盾储能材料技术有限公司 | High efficiency diaphragm material of lithium ion battery and preparation method of diaphragm material |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP2021120954A (en) | Method of preparing battery electrode plate | |
| US9564624B2 (en) | Microporous composite film with high thermostable organic/inorganic coating layer | |
| EP2603944B1 (en) | Separator with increased puncture resistance | |
| US10693170B2 (en) | Lithium air battery having multi-layered electrolyte membrane and manufacturing method thereof | |
| US3661645A (en) | Polytetrafluoroethylene battery separator and method for producing same | |
| EP3594278B1 (en) | Polyolefin microporous film | |
| JP6328355B1 (en) | Electrolyte membrane and method for producing the same | |
| KR20160146134A (en) | Manufacturing method of closslinked polyolefine separator and separator manufactured by the same method | |
| EP3675231A1 (en) | Lithium secondary battery comprising separator and manufacturing method for same | |
| JP2015185514A (en) | Composition for production of separator, separator, and power storage device | |
| JP6634543B2 (en) | Power storage device separator and method for manufacturing the same, and power storage device and method for manufacturing the same | |
| EP2871697A1 (en) | Sheet, electrode and fuel cell | |
| EP0577387A1 (en) | Separator for electrochemical cell and method of preparation | |
| KR20160129538A (en) | Polyolefin separator and the method of preparing the same | |
| CN106374075A (en) | Reticular porous composite isolation film and preparation method thereof | |
| CN112640153A (en) | Method of forming carbon-based active layer for anode of lead-carbon battery and active layer formed thereby | |
| EP3394917B1 (en) | Composite material | |
| CN113451707A (en) | Polyolefin diaphragm and preparation method thereof | |
| JP2003231772A (en) | Microporous film made of polyolefin | |
| DE102012212478A1 (en) | Polyelectrolyte membranes supported on ePTFE made with ionomer-Kynar blends | |
| EP4199234A1 (en) | Separator for lead storage battery and lead storage battery | |
| JP3948762B2 (en) | Zinc bromine secondary battery separator | |
| DE102009038252B4 (en) | Polyelectrolyte membranes added from mixtures of PFSA and sulfonated PFCB polymers | |
| CN111081949B (en) | Cross-linked polyolefin diaphragm and preparation method thereof | |
| CN109585750B (en) | Composite diaphragm and preparation method thereof |
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 | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210928 |