CN110416470B - Battery diaphragm, preparation process thereof and improved method for reducing consumption of dichloromethane - Google Patents
Battery diaphragm, preparation process thereof and improved method for reducing consumption of dichloromethane Download PDFInfo
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- CN110416470B CN110416470B CN201910724514.4A CN201910724514A CN110416470B CN 110416470 B CN110416470 B CN 110416470B CN 201910724514 A CN201910724514 A CN 201910724514A CN 110416470 B CN110416470 B CN 110416470B
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- membrane
- dsc curve
- paraffin oil
- dichloromethane
- lithium ion
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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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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- 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
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
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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
Abstract
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a battery diaphragm, a preparation process thereof and an improved method for reducing dichloromethane consumption. Wherein the improved method comprises the following steps: obtaining a DSC curve of the membrane; determining parameters of a stretching process according to a DSC curve; and the membrane is stretched to overflow paraffin oil in the membrane, so that the input amount and consumption of dichloromethane as an extracting agent are effectively reduced, the extraction efficiency is improved, and the production cost is reduced.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a battery diaphragm and a preparation process thereof, and an improved method for reducing dichloromethane consumption.
Background
Through the development of the last two decades, the lithium ion battery is superior to the traditional secondary battery in the aspects of volumetric specific energy, mass specific power, cycle life, charge and discharge efficiency and the like, and becomes a new energy industry which is preferentially supported and developed by governments in various countries. The lithium ion battery adopts a spiral winding structure, and a very fine diaphragm material with strong permeability is needed to isolate the positive electrode and the negative electrode. As one of four key materials, the diaphragm has high technical content, the cost accounts for 10% -20% of the cost of the lithium ion battery, and the profit can reach 50% -60%. The lithium ion battery diaphragm is a product with the highest gross benefit among four main materials, the domestic manufacturers probably have more than 100 families, wet diaphragm enterprises are more, but the diaphragm industry is very competitive, and all enterprises are actively developing energy-saving and consumption-reducing work to further control the production cost, so that the profit proportion is improved.
In the wet diaphragm manufacturing process in the lithium battery industry, an extraction process is the mainstream diaphragm cavity process preparation technology at present. In order to separate the paraffin oil contained in the membrane as an auxiliary raw material from the product, an extraction process is an indispensable link. Due to the flow line production, the raw material paraffin oil contained in the product can be continuously extracted by the extractant (dichloromethane) and mixed in the extractant, so that the extractant has more and more oil content, and the extraction effect of the extractant can be influenced quickly. At present, single-line dichloromethane loss of many enterprises is kept at 3-5m for carrying out heavy planting, and the cost of the diaphragm is calculated to be kept at 0.06-0.1 yuan/square meter. Therefore, by reducing the paraffin oil content in the diaphragm, the consumption of the extracting agent can be reduced, and the extracting agent can keep a continuous and stable extracting effect, so that the diaphragm product can keep good stability.
Disclosure of Invention
The invention aims to provide a battery diaphragm and a preparation process thereof, and an improved method for reducing the consumption of dichloromethane.
In order to solve the technical problem, the invention provides an improved method for reducing the consumption of dichloromethane, which comprises the following steps: obtaining a DSC curve of the membrane; determining parameters of a stretching process according to a DSC curve; and stretching the membrane to overflow the paraffin oil in the membrane.
Further, the DSC curve of the membrane is suitable for acquisition by a differential thermal analysis scanning analyzer.
Further, the parameters of the stretching process include: a temperature threshold and a draw ratio; wherein the temperature threshold is 90-120 ℃; the draw ratio is 5 to 8 times.
In a second aspect, the invention also provides a preparation process of the lithium ion battery separator, which comprises the following steps: preparing the raw materials into a membrane by a wet process; paraffin oil overflowing from the membrane; and extracting the diaphragm through dichloromethane to obtain the lithium ion battery diaphragm.
Further, the method of overflowing paraffin oil in a membrane includes: obtaining a DSC curve of the membrane; determining parameters of a stretching process according to a DSC curve; and stretching the membrane to overflow the paraffin oil in the membrane.
Further, the DSC curve of the membrane is suitable for acquisition by a differential thermal analysis scanning analyzer.
Further, the parameters of the stretching process include: a temperature threshold and a draw ratio; wherein the temperature threshold is 90-120 ℃; the draw ratio is 5 to 8 times.
In a third aspect, the invention also provides a membrane for preparing a lithium ion battery membrane, wherein the membrane is suitable for overflowing paraffin oil by the improved method.
In a fourth aspect, the invention also provides a lithium ion battery separator suitable for being prepared by the membrane as described above.
The method for improving the consumption of the dichloromethane has the advantages that the parameters of the film drawing process are determined through the DSC curve, the drawing process is carried out, part of paraffin oil in the film can overflow, the overflow amount of the paraffin oil can reach 20-40%, the input amount and the consumption of the dichloromethane serving as an extracting agent are effectively reduced, the extraction efficiency is improved, and the production cost is reduced.
Drawings
The invention is further illustrated with reference to the following figures and examples.
Fig. 1 is a process flow diagram of a process for preparing a lithium ion battery separator according to the present invention.
Detailed Description
The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic views illustrating only the basic structure of the present invention in a schematic manner, and thus show only the constitution related to the present invention.
Example 1
As shown in fig. 1, this example 1 provides an improved method for reducing the consumption of dichloromethane, comprising the steps of: step S1, obtaining a DSC curve of the diaphragm; step S2, determining parameters of the stretching process according to the DSC curve; and step S3, stretching the membrane to overflow the paraffin oil in the membrane.
Alternatively, the membrane sheet may be, for example, but not limited to, a pressed membrane sheet or a cast membrane sheet prepared using a wet process production process.
The wet process mixes liquid hydrocarbon or some small molecular substances with polyolefin resin, forms a uniform mixture after heating and melting, then cools down for phase separation, presses to obtain a membrane (a pressed membrane or a cast membrane), heats the membrane to a temperature close to the melting point, carries out bidirectional stretching to orient molecular chains, finally keeps the temperature for a certain time, and uses volatile substances to elute residual solvent, thereby preparing the mutually-communicated microporous membrane material.
Optionally, the DSC curve of the membrane is suitable for being obtained by a differential thermal analysis scanning analyzer, and the method and operation for obtaining the DSC curve by the differential thermal analysis scanning analyzer belong to the prior art, and only the test product (the membrane in this embodiment 1) is different, and therefore, the description is omitted.
Optionally, the parameters of the stretching process include: a temperature threshold and a draw ratio; wherein the temperature threshold is 90-120 deg.C, optionally 100 deg.C, 110 deg.C; the stretching ratio is 5 to 8 times, and optionally, the stretching ratio is 6 times or 7 times. In the stretching process of the membrane, the macromolecule PE in the membrane absorbs a large amount of heat, the molecular chain moves, the paraffin oil in the microporous membrane material is extruded, about 20-40% (the weighing calculation proportion of the overflowed paraffin oil) of the paraffin oil overflows the surface of the membrane, the extraction consumption (namely dichloromethane consumption) can be reduced by 30-50%, if the dichloromethane consumption is kept 0.03-0.06 yuan/square meter according to the area calculation of the membrane, the extraction efficiency is improved, and the aims of saving energy, reducing consumption and controlling the production cost are fulfilled.
Further, in the case of high temperature and high draw ratio, the amount of paraffin oil spilled increases, but has a negative influence on the properties of the product, and therefore, it is not preferable to set the drawing temperature to a value exceeding the upper limit of the temperature threshold, and the draw ratio cannot exceed 5 to 8 times.
Example 2
Referring to fig. 1, on the basis of example 1, this example 2 provides a preparation process of a lithium ion battery separator, including: preparing the raw materials into a membrane by a wet process; paraffin oil overflowing from the membrane; and extracting the diaphragm through dichloromethane to obtain the lithium ion battery diaphragm.
Further, the method of overflowing paraffin oil in the membrane, namely the improved method for reducing the consumption of dichloromethane, comprises the following steps: obtaining a DSC curve of the membrane; determining parameters of a stretching process according to a DSC curve; and stretching the membrane to overflow the paraffin oil in the membrane.
Further, the DSC curve of the membrane is suitable for acquisition by a differential thermal analysis scanning analyzer.
Further, the parameters of the stretching process include: a temperature threshold and a draw ratio; wherein the temperature threshold is 90-120 deg.C, optionally 100 deg.C, 110 deg.C; the stretching ratio is 5 to 8 times, and optionally, the stretching ratio is 6 times or 7 times. At high temperatures and high draw ratios, the amount of paraffin oil spilled increases, but has a negative effect on the product properties, and therefore it is not advisable to set the draw temperature above the upper limit of the temperature threshold, nor to exceed a draw ratio of 5 to 8 times.
For the improved method and the specific implementation process for reducing the consumption of dichloromethane, refer to the related discussion of example 1, and are not repeated herein.
Example 3
On the basis of example 1, this example 3 provides a membrane for lithium ion battery membrane preparation, which is suitable for overflowing paraffin oil by the improved method for reducing dichloromethane consumption as described above.
For the specific implementation of the improved method for reducing the consumption of dichloromethane, reference is made to the related discussion of example 1, and further description is omitted here.
Example 4
On the basis of example 3, this example 4 provides a lithium ion battery separator that is suitable for being prepared by the membrane as described above.
For the specific structure and implementation of the membrane, refer to the related discussion of embodiment 3, and are not described herein again.
In conclusion, the battery diaphragm and the preparation process thereof, and the improved method for reducing the consumption of dichloromethane determine the parameters of the diaphragm stretching process through the DSC curve, and the stretching process is carried out on the parameters, so that part of paraffin oil in the diaphragm can overflow, the input amount and the consumption of dichloromethane as an extracting agent are effectively reduced, the extraction efficiency is improved, and the production cost is reduced; by controlling the temperature threshold and the stretching ratio of the stretching process, the overflowing amount of the paraffin oil can reach 20-40%, the consumption of dichloromethane is reduced by 30-50%, and the aims of saving energy, reducing consumption and controlling production cost are fulfilled.
In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.
Claims (6)
1. An improved process for reducing methylene chloride consumption comprising:
obtaining a DSC curve of the membrane;
determining parameters of a stretching process according to a DSC curve; and
stretching the membrane to enable paraffin oil in the membrane to overflow;
the parameters of the stretching process include: a temperature threshold and a draw ratio; wherein
The temperature threshold is 90-120 ℃;
the draw ratio is 5 to 8 times.
2. The improved method of claim 1,
the DSC curve of the membrane is suitable for acquisition by a differential thermal analysis scanning analyzer.
3. A preparation process of a lithium ion battery separator is characterized by comprising the following steps:
preparing the raw materials into a membrane by a wet process;
paraffin oil overflowing from the membrane;
extracting a diaphragm through dichloromethane to obtain the lithium ion battery diaphragm;
the method of spilling paraffin oil in a membrane includes:
obtaining a DSC curve of the membrane;
determining parameters of a stretching process according to a DSC curve; and
stretching the membrane to enable paraffin oil in the membrane to overflow;
the parameters of the stretching process include: a temperature threshold and a draw ratio; wherein
The temperature threshold is 90-120 ℃;
the draw ratio is 5 to 8 times.
4. The production process according to claim 3,
the DSC curve of the membrane is suitable for acquisition by a differential thermal analysis scanning analyzer.
5. A diaphragm for preparing a lithium ion battery diaphragm is characterized in that,
the membrane is adapted to spill paraffin oil by the improved method of claim 1.
6. A lithium ion battery separator is characterized in that,
the lithium ion battery separator is suitable for being prepared by the membrane of claim 5.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910724514.4A CN110416470B (en) | 2019-08-07 | 2019-08-07 | Battery diaphragm, preparation process thereof and improved method for reducing consumption of dichloromethane |
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| CN201910724514.4A CN110416470B (en) | 2019-08-07 | 2019-08-07 | Battery diaphragm, preparation process thereof and improved method for reducing consumption of dichloromethane |
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| CN110416470A CN110416470A (en) | 2019-11-05 |
| CN110416470B true CN110416470B (en) | 2022-03-11 |
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| CN110828751B (en) * | 2019-11-06 | 2022-04-05 | 江苏厚生新能源科技有限公司 | Preparation method of polyethylene diaphragm with multilayer microporous structure |
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