CN114204213A - Ultrathin polyolefin separator and application - Google Patents
Ultrathin polyolefin separator and application Download PDFInfo
- Publication number
- CN114204213A CN114204213A CN202010897623.9A CN202010897623A CN114204213A CN 114204213 A CN114204213 A CN 114204213A CN 202010897623 A CN202010897623 A CN 202010897623A CN 114204213 A CN114204213 A CN 114204213A
- Authority
- CN
- China
- Prior art keywords
- equal
- controlled
- less
- polyolefin
- polyolefin separator
- 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
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
Abstract
The invention discloses an ultrathin polyolefin diaphragm and application thereof, wherein the polyolefin diaphragm mainly comprises polyethylene, and M of the polyethylenew35 to 50 ten thousand, the molecular weight distribution is less than or equal to 8, the melt index is 0.4 to 5 at 190 ℃ and 21.6KG, and the melting point is 134-139 ℃. The invention screens the polyethylene material with specific molecular weight and melting characteristic, and controls the extrusion amount, the stretching temperature and the stretching magnification in the processing process to obtain the ultrathin polyolefin diaphragm with the thickness less than or equal to 7 mu m, and the diaphragm surface is flat and good, and can be continuously produced in an industrialized way.
Description
Technical Field
The invention belongs to the field of lithium battery diaphragm materials, and particularly relates to an ultrathin polyolefin diaphragm and application thereof.
Background
With the development of lithium ion batteries in the directions of high energy density, high-rate charge and discharge and long cycle, the requirements on polyolefin diaphragms are more and more demanding, wherein one of the requirements on diaphragms is ultra-thinning, and more space is provided for high-energy-density anodes/cathodes.
In the prior art, certain technical obstacles exist in the production of ultrathin diaphragms with the thickness of less than 7 microns, membrane surface defects are easy to occur, membrane breakage phenomena are possible to occur, and normal production cannot be realized.
Disclosure of Invention
In view of the above, the present invention provides an ultrathin polyolefin membrane and applications thereof, wherein the thickness of the obtained polyolefin membrane is less than or equal to 7 μm, the membrane surface is flat and good, and continuous industrial production can be achieved.
In order to achieve the purpose, the invention provides the following technical scheme:
the invention provides an ultrathin polyolefin diaphragm, which mainly consists of polyethylene, wherein M of the polyethylenew35-50 ten thousand, the molecular weight distribution is less than or equal to 8, the melt index at 190 ℃ and 21.6KG is 0.4-5, and the melting point is 134-139 ℃;
the preparation of the polyolefin separator comprises the following steps:
(1) extruding the polyethylene and plasticizer through a die, cooling to form a gel-like sheet; wherein the extrusion amount is controlled to be less than or equal to 180kg/h, the casting speed is controlled to be less than or equal to 15m/min, and the casting temperature is controlled to be less than or equal to 30 ℃;
(2) sequentially stretching the gel-like sheet longitudinally and transversely; wherein the longitudinal stretching temperature is controlled to be less than or equal to 110 ℃, the transverse stretching temperature is controlled to be between 110 ℃ and 140 ℃, and the surface tension ratio is more than 170 times.
Preferably, in the step (2), the longitudinal stretching ratio is controlled to be 5 to 10 times, and the transverse stretching ratio is controlled to be 12 to 20 times.
As a preferable technical scheme, the thickness of the polyolefin separator is less than or equal to 7 mu m.
The invention also provides application of the ultrathin polyolefin diaphragm as a battery diaphragm, wherein a battery comprises a positive electrode, a negative electrode, an electrolyte and the battery diaphragm positioned between the positive electrode and the negative electrode, and the battery diaphragm comprises the polyolefin diaphragm.
The invention has the beneficial effects that:
the invention screens the polyethylene material with specific molecular weight and melting characteristic, and controls the extrusion amount, the stretching temperature and the stretching magnification in the processing process to obtain the ultrathin polyolefin diaphragm with the thickness less than or equal to 7 mu m, and the diaphragm surface is flat and good, and can be continuously produced in an industrialized way.
Detailed Description
The present invention is further described with reference to specific examples to enable those skilled in the art to better understand the present invention and to practice the same, but the examples are not intended to limit the present invention.
Example 1:
a. melting the ingredients: weighing polyethylene powder and M of polyethylene powderw40 ten thousand, a molecular weight distribution of 6, a melt index of 3 at 190 ℃ and 21.6KG, a melting point of 135 ℃; then respectively putting 30 wt% of polyethylene powder and 70 wt% of white oil into a double screw to mix and melt to form a high-temperature melt;
b. die head extrusion: melting the materials in a double screw into high-temperature melt, accurately metering the high-temperature melt by a metering pump, and allowing the high-temperature melt to flow out of a slit opening of a die head;
c. cooling and forming the cast sheet: the high-temperature melt flows out of a slot of the die head to the surface of the chill roll, and is rapidly cooled and formed into a gel sheet; wherein the extrusion amount is controlled at 120kg/h, the casting speed is controlled at 10m/min, and the casting temperature is controlled at 25 ℃;
d. and (3) bidirectional stretching: sequentially longitudinally stretching and transversely stretching the gel-like sheet to obtain an oil-containing film; wherein the machine direction "MD" (die extrusion direction) draw ratio is 10 times, the machine direction drawing temperature is 100 ℃, the transverse direction "TD" (perpendicular to MD) draw ratio is 18 times, and the transverse direction drawing temperature is 130 ℃;
e. and (3) extraction: immersing the oil-containing film into an extraction tank containing dichloromethane to extract white oil;
f. and (3) drying: putting the extracted film into a drying oven, and volatilizing an extracting agent dichloromethane to obtain a dried film;
g. transversely stretching and expanding: feeding the dried film into a transverse drawing machine, heating and transversely drawing and expanding to ensure that the film holes are not shrunk;
h. heat setting: and (3) feeding the transversely-pulled film into a heat setting device, eliminating the internal stress of the film, and improving the heat shrinkage performance of the diaphragm to obtain the polyolefin diaphragm.
Comparative example 1:
comparative example 1 differs from example 1 in that: in step a, M of polyethylene powderw60 million, a molecular weight distribution of 10, a melt index of 7 at 190 ℃ and 21.6KG, and a melting point of 132 ℃.
Comparative example 2:
comparative example 2 differs from example 1 in that: in the step d, the longitudinal stretching ratio is 5 times, the longitudinal stretching temperature is 120 ℃, the transverse stretching ratio is 10 times, and the transverse stretching temperature is 125 ℃.
The polyolefin separators obtained in example 1 and comparative examples 1 to 2 were subjected to performance tests under the same conditions, and the results are shown in table 1.
TABLE 1 comparison of results of membrane Performance tests
From the performance test data in table 1, in example 1, a polyethylene material with a specific molecular weight and melting property is selected, and the extrusion amount, the stretching temperature and the stretching ratio are controlled in the processing process, so that the ultrathin polyolefin diaphragm with the thickness of less than or equal to 7 μm is obtained, the diaphragm surface is flat and good, and continuous industrial production can be realized. Comparative example 1 polyethylene having a larger molecular weight, a wider molecular weight distribution, and a larger melt index was selected, the produced separator had slight streaks, bright spots, scratches, and the like, white spots on the film surface similar to mold spots, and the thickness uniformity was poor. The stretching process of comparative example 2 was different from that of example 1, and only a diaphragm of 16 μm was obtained, and the film surface had a slight watermark and a slight film surface color difference, and the normal production was not possible due to continuous film breakage.
The above-mentioned embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of the present invention is not limited thereto. The equivalent substitution or change made by the technical personnel in the technical field on the basis of the invention is all within the protection scope of the invention. The protection scope of the invention is subject to the claims.
Claims (4)
1. An ultra-thin polyolefin separator characterized by: the polyolefin separator consists essentially of polyethylene, M of whichw35-50 ten thousand, the molecular weight distribution is less than or equal to 8, the melt index at 190 ℃ and 21.6KG is 0.4-5, and the melting point is 134-139 ℃;
the preparation of the polyolefin separator comprises the following steps:
(1) extruding the polyethylene and plasticizer through a die, cooling to form a gel-like sheet; wherein the extrusion amount is controlled to be less than or equal to 180kg/h, the casting speed is controlled to be less than or equal to 15m/min, and the casting temperature is controlled to be less than or equal to 30 ℃;
(2) sequentially stretching the gel-like sheet longitudinally and transversely; wherein the longitudinal stretching temperature is controlled to be less than or equal to 110 ℃, the transverse stretching temperature is controlled to be between 110 ℃ and 140 ℃, and the surface tension ratio is more than 170 times.
2. The ultra-thin polyolefin separator of claim 1, wherein: in the step (2), the longitudinal stretching ratio is controlled to be 5-10 times, and the transverse stretching ratio is controlled to be 12-20 times.
3. The ultra-thin polyolefin separator according to claim 1 or 2, characterized in that: the thickness of the polyolefin diaphragm is less than or equal to 7 mu m.
4. A battery comprising a positive electrode, a negative electrode, an electrolyte, and a battery separator between the positive electrode and the negative electrode, wherein: the battery separator includes the polyolefin separator according to any one of claims 1 to 3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010897623.9A CN114204213A (en) | 2020-08-31 | 2020-08-31 | Ultrathin polyolefin separator and application |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010897623.9A CN114204213A (en) | 2020-08-31 | 2020-08-31 | Ultrathin polyolefin separator and application |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114204213A true CN114204213A (en) | 2022-03-18 |
Family
ID=80644308
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010897623.9A Pending CN114204213A (en) | 2020-08-31 | 2020-08-31 | Ultrathin polyolefin separator and application |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114204213A (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110931688A (en) * | 2019-12-13 | 2020-03-27 | 重庆云天化纽米科技股份有限公司 | Highly extended polyolefin separator and applications |
-
2020
- 2020-08-31 CN CN202010897623.9A patent/CN114204213A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110931688A (en) * | 2019-12-13 | 2020-03-27 | 重庆云天化纽米科技股份有限公司 | Highly extended polyolefin separator and applications |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112768764B (en) | High-strength solid electrolyte membrane | |
| CN112886067B (en) | Preparation method of synchronous substrate-supported solid composite electrolyte membrane | |
| CN104362276B (en) | A kind of polyethene microporous membrane, preparation method and lithium ion battery | |
| CN110828751B (en) | Preparation method of polyethylene diaphragm with multilayer microporous structure | |
| CN111086181A (en) | Preparation method of lithium battery diaphragm | |
| CN109560235A (en) | A kind of new type lithium ion battery aramid fiber diaphragm preparation method | |
| CN113013552B (en) | Battery diaphragm and preparation method thereof | |
| CN110931688B (en) | Highly extended polyolefin separator and applications | |
| WO2024001489A1 (en) | Lithium-ion battery separators and preparation methods thereof | |
| WO2021164143A1 (en) | Polyolefin porous membrane and preparation method therefor | |
| CN113285176A (en) | Polyolefin diaphragm with high porosity and uniform pore diameter for lithium ion battery, preparation method of polyolefin diaphragm and lithium ion battery | |
| CN112886138A (en) | Microporous membrane with different micropores on two surfaces and preparation method thereof | |
| CN110649211B (en) | Low-closed-pore high-rupture-membrane polyolefin diaphragm and preparation method thereof | |
| CN114204213A (en) | Ultrathin polyolefin separator and application | |
| CN112670663A (en) | Heat-resistant lithium battery diaphragm and preparation method and application thereof | |
| CN112670665A (en) | High-performance lithium battery diaphragm and preparation method thereof | |
| CN110635092A (en) | Polar polyolefin separator and preparation method thereof | |
| CN110181837B (en) | Production method for controlling aperture of lithium ion secondary battery diaphragm | |
| JP2022517293A (en) | Method for Producing Polyolefin Porous Membrane | |
| CN104064710A (en) | Production technology of high-porosity lithium battery membrane by adopting ceramic coating | |
| CN110690395A (en) | Preparation method of multilayer polyethylene diaphragm | |
| CN116073072A (en) | Battery diaphragm and preparation method and application thereof | |
| CN112864531B (en) | Diaphragm, preparation method of diaphragm and battery | |
| CN114274484A (en) | Polyethylene microporous membrane, preparation method thereof and lithium ion battery | |
| CN111933873A (en) | Diaphragm with uniform aperture 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 |