CN105390641B - Manufacturing process of multilayer composite lithium ion microporous membrane - Google Patents
Manufacturing process of multilayer composite lithium ion microporous membrane Download PDFInfo
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- CN105390641B CN105390641B CN201510711585.2A CN201510711585A CN105390641B CN 105390641 B CN105390641 B CN 105390641B CN 201510711585 A CN201510711585 A CN 201510711585A CN 105390641 B CN105390641 B CN 105390641B
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- stretching
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/403—Manufacturing processes of separators, membranes or diaphragms
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Manufacturing & Machinery (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Laminated Bodies (AREA)
- Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
Abstract
The invention discloses a manufacturing process of a multilayer composite lithium ion microporous membrane, which is characterized by sequentially comprising the following steps of: the method comprises the steps of sheeting, tape casting, heat treatment, stretching, heat setting, slitting and film collecting. Compared with the prior art, the process increases the stretching multiplying power, reduces the distance between the casting devices of the extrusion die head, and ensures that the three-layer film has better strength and balance after being formed. The polypropylene material adopts the polypropylene material with the ratio of the weight average molecular weight to the number average molecular weight larger than 3.8, the relaxation time of the ultrahigh molecular weight component is long, the temperature dependence is small, the ultrahigh molecular weight component is uniformly dispersed, and the influence of the changes of the parameters such as the plastic fat temperature, the stretching magnification and the like on the ultrahigh molecular weight component is small in the stretching process, so that the strength of the microporous membrane is increased, and the air permeability and the balance are enhanced.
Description
Technical Field
The invention relates to a manufacturing process of a multilayer composite lithium ion microporous membrane.
Background
The batteries commonly used in the world at present are: 4 kinds of disposable alkaline zinc-manganese batteries, chargeable nickel batteries, lead-acid storage batteries, lithium ion batteries and the like. The lithium ion battery has become the main power source of various electronic products due to its advantages of high efficiency, safety, high working voltage, high energy density, long cycle life, no memory effect, no pollution and the like.
Although China is one of the most important lithium ion battery producing countries in the world, the quality of lithium ion battery products is at the middle and low end levels. The lithium ion microporous membrane is seriously dependent on import, and data shows that the amount of the lithium ion microporous membrane imported from China in 2013 from the countries of the Japan, the America, the Korean and the like is 3.2 hundred million dollars. The research and development of lithium ion microporous membranes, particularly the industrialization aspect, are far behind the advanced level in the world in China.
The microporous membrane is an important component of the lithium ion battery, and the quality of the microporous membrane directly influences the characteristics of the battery, such as internal resistance, capacity, cycle performance and the like. The existing lithium ion microporous membrane is mostly a single-layer membrane, and the poor strength and air permeability of the microporous membrane cause the poor cycle performance and short service life of the existing lithium ion battery, so how to improve the performance of the microporous membrane is a technical problem which is urgently needed to be solved at present.
Disclosure of Invention
The invention aims to solve the technical problems mentioned above and provides a manufacturing process of a multilayer composite lithium ion microporous membrane.
The invention is realized by the following technical scheme: the manufacturing process of the multilayer composite lithium ion microporous membrane is characterized by sequentially comprising the following steps of: a sheet forming step, wherein an extruder is used for three-layer co-extrusion molding in a mode that the middle layer is made of a polyethylene material and the upper layer and the lower layer are made of a polypropylene material to obtain a three-layer melt formed by the polyethylene material and the polypropylene material which are in contact with each other; a tape casting step, namely rapidly cooling and shaping the three layers of melts into three layers of films under the action of tape casting equipment; a heat treatment step, wherein hot air equipment is arranged to continuously blow hot air to the three layers of films in the heating furnace; a stretching step, stretching the three-layer film by using stretching equipment; a heat setting step, controlling the temperature to be 125-135 ℃ so that the three layers of films stay for 20-30 seconds; a slitting step, namely processing the multilayer film to a required shape in a vacuum box by using an air knife; and a film collecting step, namely curling the multilayer film on a film collecting roller.
Preferably, the extruder in the sheeting step is provided with an extrusion die at the melt outlet, the extrusion die is close to the casting device, and the distance between the extrusion die and the casting device is less than 7mm.
Preferably, the temperature of the extruder in the sheeting step is 210 to 230 ℃ and the draw ratio is 200 to 250.
Preferably, the casting device and the stretching device are both provided with a roller shaft rotating at a constant speed and a motor driving the roller shaft to rotate, and the roller shafts in the casting device and the stretching device are driven by at least one motor.
Preferably, the duration of the hot air device continuously acting on the composite film in the heat treatment step is 5 to 7 hours, and the temperature is 120 to 130 ℃.
Preferably, the stretching step comprises a cold stretching step and a hot stretching step in sequence; the temperature of the roll shaft in the cold drawing step is 40-50 ℃, and the drawing ratio is 15-25%; the temperature of the roller shaft in the hot stretching step is 115-125 ℃, and the stretching ratio is 110-120%.
Preferably, the polypropylene material has a ratio of weight average molecular weight to number average molecular weight of more than 3.8.
The beneficial effects are that: compared with the prior art, the process for manufacturing the multilayer composite lithium ion microporous membrane increases the stretching magnification, reduces the distance between casting devices of an extrusion die, and ensures that the strength and the balance of the three-layer thin membrane after film formation are better. The polypropylene material adopts the polypropylene material with the ratio of the weight average molecular weight to the number average molecular weight larger than 3.8, the relaxation time of the ultrahigh molecular weight component is long, the temperature dependence is small, the ultrahigh molecular weight component is uniformly dispersed, and the influence of the changes of the parameters such as the plastic fat temperature, the stretching multiplying power and the like on the ultrahigh molecular weight component is small in the stretching process, so that the strength of the microporous membrane is increased, and the air permeability and the balance are enhanced.
Detailed Description
The manufacturing process of the multilayer composite lithium ion microporous membrane is characterized by sequentially comprising the following steps of: a sheet forming step, wherein an extruder is used for three-layer co-extrusion molding in a mode that the middle layer is made of a polyethylene material and the upper layer and the lower layer are made of a polypropylene material to obtain a three-layer melt formed by the polyethylene material and the polypropylene material which are in contact with each other; casting, namely rapidly cooling and shaping the three layers of melts into three layers of films under the action of casting equipment; a heat treatment step, wherein hot air equipment is arranged to continuously blow hot air to the three layers of films in the heating furnace; a stretching step, stretching the three-layer film by using stretching equipment; a heat setting step, controlling the temperature to be 125-135 ℃ to enable the three-layer film to stay for 20-30 seconds; a slitting step, namely processing the multilayer film to a required shape in a vacuum box by using an air knife; and a film collecting step, namely curling the multilayer film on a film collecting roller.
Preferably, the extruder in the sheeting step is provided with an extrusion die at the melt outlet, the extrusion die is close to the casting device, and the distance between the extrusion die and the casting device is less than 7mm.
Preferably, the temperature of the extruder in the sheeting step is 210 to 230 ℃ and the draw ratio is 200 to 250.
Preferably, the casting device and the stretching device are both provided with a roller shaft rotating at a constant speed and a motor driving the roller shaft to rotate, and the roller shafts in the casting device and the stretching device are driven by at least one motor.
Preferably, the duration of the hot air device continuously acting on the composite film in the heat treatment step is 5 to 7 hours, and the temperature is 120 to 130 ℃.
Preferably, the stretching step comprises a cold stretching step and a hot stretching step in sequence; the temperature of the roll shaft in the cold drawing step is 40-50 ℃, and the drawing ratio is 15-25%; the temperature of the roller shaft in the hot stretching step is 115-125 ℃, and the stretching ratio is 110-120%.
Preferably, the polypropylene material has a ratio of weight average molecular weight to number average molecular weight of more than 3.8.
The manufacturing process of the multilayer composite lithium ion microporous membrane overcomes the following technical difficulties: the three-layer composite material of polyethylene raw material and polypropylene raw material is selected to obtain an ideal lamellar crystal structure under high-rate stretching; the three-layer composite material can not generate cracks because the polypropylene film is easy to form spherulites at overhigh temperature, and can not generate fine wrinkles because the surface friction force of the polypropylene film is large at overlow temperature; therefore, the product has good quality, improved yield, low thermal relaxation and good air permeability.
The above embodiments are only for illustrating the technical solutions of the present invention and are not limited thereto, and any modification or equivalent replacement without departing from the spirit and scope of the present invention should be covered within the technical solutions of the present invention.
Claims (2)
1. The manufacturing process of the multilayer composite lithium ion microporous membrane is characterized by sequentially comprising the following steps of: a sheet forming step, wherein an extruder is used for three-layer co-extrusion molding in a mode that the middle layer is made of a polyethylene material and the upper layer and the lower layer are made of a polypropylene material to obtain a three-layer melt formed by the polyethylene material and the polypropylene material which are in contact with each other; casting, namely rapidly cooling and shaping the three layers of melts into three layers of films under the action of casting equipment; a heat treatment step, wherein hot air equipment is arranged to continuously blow hot air to the three layers of films in the heating furnace; a stretching step, stretching the three-layer film by using stretching equipment; a heat setting step, controlling the temperature to be 125-135 ℃ so that the three layers of films stay for 20-30 seconds; a slitting step, namely processing the multilayer film to a required shape in a vacuum box by using an air knife; a film collecting step, namely curling a plurality of layers of thin films on a film collecting roller shaft; an extrusion die head is arranged at a melt outlet of the extruder in the sheet forming step, the extrusion die head is close to casting equipment, and the distance between the extrusion die head and the casting equipment is less than 7mm; the temperature of an extruder in the sheet forming step is 210-230 ℃, and the stretching ratio is 200-250 times; the casting equipment and the stretching equipment are both provided with a roll shaft rotating at a constant speed and a motor driving the roll shaft to rotate, and the roll shafts in the casting equipment and the stretching equipment are driven by at least one motor; in the heat treatment step, the hot air equipment continuously acts on the composite film for 5 to 7 hours at the temperature of between 120 and 130 ℃; the stretching step sequentially comprises a cold stretching step and a hot stretching step; the temperature of the roll shaft in the cold drawing step is 40-50 ℃, and the drawing ratio is 15-25%; the temperature of the roller shaft in the hot stretching step is 115-125 ℃, and the stretching ratio is 110-120%.
2. The manufacturing process of the multilayer composite lithium ion microporous membrane according to claim 1, characterized in that the polypropylene material is a polypropylene material with the ratio of weight average molecular weight to number average molecular weight of more than 3.8.
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| CN201510711585.2A CN105390641B (en) | 2015-10-28 | 2015-10-28 | Manufacturing process of multilayer composite lithium ion microporous membrane |
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| CN201510711585.2A CN105390641B (en) | 2015-10-28 | 2015-10-28 | Manufacturing process of multilayer composite lithium ion microporous membrane |
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| CN105390641A CN105390641A (en) | 2016-03-09 |
| CN105390641B true CN105390641B (en) | 2017-12-08 |
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| CN107877960A (en) * | 2017-11-17 | 2018-04-06 | 江门市蓬江区华龙包装材料有限公司 | The co-extrusion hot pressing functional membrane of disposable cane pulp container |
| CN113659281B (en) * | 2021-08-09 | 2023-06-09 | 界首市天鸿新材料股份有限公司 | Three-layer co-extrusion diaphragm for lithium battery and stretching process thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102241142A (en) * | 2011-05-16 | 2011-11-16 | 中材科技股份有限公司 | Method for producing lithium battery diaphragm and transverse stretcher |
| CN104022249A (en) * | 2014-06-26 | 2014-09-03 | 佛山市盈博莱科技有限公司 | Three-layer lithium battery diaphragm and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CA2249504A1 (en) * | 1997-10-09 | 1999-04-09 | Asahi Kogaku Kogyo Kabushiki Kaisha | Producing apparatus of film with through-holes |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102241142A (en) * | 2011-05-16 | 2011-11-16 | 中材科技股份有限公司 | Method for producing lithium battery diaphragm and transverse stretcher |
| CN104022249A (en) * | 2014-06-26 | 2014-09-03 | 佛山市盈博莱科技有限公司 | Three-layer lithium battery diaphragm and preparation method thereof |
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Denomination of invention: Manufacturing process of multilayer composite lithium ion microporous membrane Effective date of registration: 20210114 Granted publication date: 20171208 Pledgee: China Co. truction Bank Corp Jiangmen branch Pledgor: JIANGMEN PENGJIANG HUALONG PACKING MATERIAL Co.,Ltd. Registration number: Y2021440000010 |