CN112490589A - Diaphragm and lamination process using same - Google Patents
Diaphragm and lamination process using same Download PDFInfo
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- CN112490589A CN112490589A CN202010268917.5A CN202010268917A CN112490589A CN 112490589 A CN112490589 A CN 112490589A CN 202010268917 A CN202010268917 A CN 202010268917A CN 112490589 A CN112490589 A CN 112490589A
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- 238000000034 method Methods 0.000 title claims abstract description 34
- 230000008569 process Effects 0.000 title claims abstract description 28
- 238000003475 lamination Methods 0.000 title claims abstract description 27
- 238000002360 preparation method Methods 0.000 claims abstract description 21
- 230000003068 static effect Effects 0.000 claims abstract description 19
- 230000009471 action Effects 0.000 claims abstract description 18
- 230000005611 electricity Effects 0.000 claims abstract description 18
- 238000001179 sorption measurement Methods 0.000 claims abstract description 14
- 238000005520 cutting process Methods 0.000 claims abstract description 9
- 239000012528 membrane Substances 0.000 claims description 28
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 10
- 238000003851 corona treatment Methods 0.000 claims description 9
- 238000005507 spraying Methods 0.000 claims description 7
- 238000001035 drying Methods 0.000 claims description 5
- 229920005569 poly(vinylidene fluoride-co-hexafluoropropylene) Polymers 0.000 claims description 5
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 claims description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 claims description 4
- 239000000919 ceramic Substances 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 4
- 239000004745 nonwoven fabric Substances 0.000 claims description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 2
- 239000004760 aramid Substances 0.000 claims description 2
- 229920003235 aromatic polyamide Polymers 0.000 claims description 2
- 229910001593 boehmite Inorganic materials 0.000 claims description 2
- 239000001913 cellulose Substances 0.000 claims description 2
- 229920002678 cellulose Polymers 0.000 claims description 2
- 239000011247 coating layer Substances 0.000 claims description 2
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 claims description 2
- 229910052943 magnesium sulfate Inorganic materials 0.000 claims description 2
- 235000019341 magnesium sulphate Nutrition 0.000 claims description 2
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims description 2
- 239000004926 polymethyl methacrylate Substances 0.000 claims description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims description 2
- 239000011159 matrix material Substances 0.000 claims 1
- 229910052744 lithium Inorganic materials 0.000 abstract description 8
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 7
- 230000008595 infiltration Effects 0.000 abstract description 6
- 238000001764 infiltration Methods 0.000 abstract description 6
- 239000003792 electrolyte Substances 0.000 abstract description 5
- 230000000694 effects Effects 0.000 abstract description 4
- 230000000052 comparative effect Effects 0.000 description 18
- 238000007731 hot pressing Methods 0.000 description 8
- 239000000428 dust Substances 0.000 description 6
- 239000002131 composite material Substances 0.000 description 5
- 239000012535 impurity Substances 0.000 description 5
- 238000013329 compounding Methods 0.000 description 4
- 238000004804 winding Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 238000002955 isolation Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 230000000284 resting effect Effects 0.000 description 3
- 238000007086 side reaction Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 229920001940 conductive polymer Polymers 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 150000002641 lithium Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 238000009832 plasma treatment Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- 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
- H01M10/058—Construction or manufacture
- H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
-
- 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
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Secondary Cells (AREA)
- Cell Separators (AREA)
Abstract
The invention relates to the technical field of a lithium battery cell structure, and provides a diaphragm and a lamination process using the diaphragm aiming at the problems of poor flatness of the cell structure and poor wettability of an interface electrolyte in the prior art, wherein the lamination process comprises the following steps: 1) preparing a first unit: placing the positive pole pieces above the diaphragm at equal intervals, performing adsorption connection through electrostatic action, and cutting to form a first unit; 2) preparing a second unit: meanwhile, the negative pole pieces are arranged above the second diaphragm at equal intervals, are connected through electrostatic action and are cut to form a second unit; 3) preparing an electric core: and sequentially stacking the first unit and the second unit to obtain the battery cell, wherein the static electricity carried by the diaphragm after treatment is 800-3000V. The invention adopts the diaphragm with stronger static electricity, and the diaphragm and the anode and the cathode are respectively connected together through the electrostatic adsorption effect of the diaphragm, so that the infiltration performance of the battery cell can be greatly improved, the infiltration time is shortened, the preparation process is simple, and the high-quality yield is high.
Description
Technical Field
The invention relates to the technical field of lithium battery cell structures, in particular to a diaphragm and a lamination process using the diaphragm.
Background
In the process of preparing a battery core structure of a lithium battery, in the prior art scheme, a diaphragm, an anode, a cathode and the diaphragm are usually connected and fixed by hot pressing, but the anode and the cathode which are actually produced and manufactured are often bent to a certain degree, and after the anode and the cathode are fixed by using the viscous diaphragm, internal stress exists in a first unit due to different bending deformation directions and sizes of the anode and the cathode, so that the first unit is not flat, the unevenness can affect the alignment degree of subsequent laminations and the flatness of a final battery core on one hand, and finally the finished product rate is affected; on the other hand, the non-uniformity of the interface between the pole piece and the diaphragm inside the battery cell can be caused, and finally, the lithium separation inside the battery cell is serious and the performance of the battery cell is influenced. In addition, the viscous diaphragm can form a strong bonding interface after hot pressing and compounding of the positive and negative pole pieces, and the interface can lead to the fact that the battery cell is difficult to be soaked by the electrolyte, so that the soaking time is prolonged, the production efficiency is reduced, and the performance of the battery cell is reduced.
The invention discloses a novel isolating film composite winding process and a lithium ion battery, and the isolating film composite winding process is characterized in that a pole piece and an isolating film are subjected to hot-pressing compounding in advance and then are wound into a bare cell, and the process can greatly improve the problems of tab alignment degree change, winding core deformation, isolating film wrinkling and the like caused by the stress of the isolating film in the traditional winding cell; the lithium ion battery assembled by the pole pieces with the composite structure is characterized in that the interface contact between the pole pieces in the battery is good, the battery is not easy to deform, and the cycle life is longer.
The defects are that the flatness of the cell structure is poor and the interface of the pole piece and the diaphragm is difficult to be soaked by electrolyte.
Disclosure of Invention
The invention provides a diaphragm and a laminating process using the diaphragm, aiming at overcoming the problems of poor flatness of a cell structure and poor wettability of an interface electrolyte of a lithium battery in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
a membrane having an electrostatic charge of 800-.
When the static electricity carried by the diaphragm is smaller than the range, the composite connection of the diaphragm and the pole piece cannot be effectively realized; when the static electricity carried by the diaphragm is larger than the range, dust in the air is easily adsorbed, so that the pollution of the battery core is caused, on one hand, the final yield of the battery is influenced, and on the other hand, the adsorbed dust exists in the battery core as impurities, so that the performance of the battery is deteriorated.
Preferably, the separator includes one of a PE separator, a PP separator, a multilayer separator in which PE and PP are arbitrarily combined, a non-woven fabric separator, and a coating separator.
Preferably, the substrate of the nonwoven fabric separator includes at least one of PI, PA, PVDF-HFP, PAN, cellulose, PE, PP, and the like.
Preferably, the coating layer of the coating separator includes at least one of ceramic particles, aramid, PVDF-HFP, PAN, PVA, PMMA, and derivatives thereof.
Preferably, the ceramic particles comprise at least one of alumina, boehmite, barium sulfate, magnesium sulfate, and silica.
The above is a conventional separator used at present, and the method is applicable to all separators used in lithium batteries at present.
The preparation method of the diaphragm comprises the following preparation steps: spraying absolute ethyl alcohol on the diaphragm before lamination; and then carrying out corona treatment and drying to obtain the electrostatic diaphragm.
After the membrane treated by the absolute ethyl alcohol is subjected to corona treatment, the electrostatic charge of the membrane can be controlled to be 800-3000V, and the membrane cannot be too large, so that the problem that the yield of the battery and the final battery performance such as self-discharge and circulation stability are influenced because a large amount of dust is adsorbed by the membrane in the use process due to the too large electrostatic charge can be avoided; meanwhile, the method is beneficial to enhancing the bonding performance between the diaphragm and the negative electrode, ensuring the smooth proceeding of the lamination process and reducing the cost rate of the battery, because the hydrophilicity of the surface of the diaphragm is obviously increased if the plasma treatment is independently utilized, and because the graphite negative electrode is made of a hydrophobic material and is not well bonded with the surface of the diaphragm with high hydrophilicity, the interface bonding performance between the diaphragm and the negative electrode plate is poor. In addition, the membrane treated by the absolute ethyl alcohol is treated by the plasma, so that the damage of the plasma to the mechanical strength of the membrane can be reduced, the mechanical strength of the membrane after treatment is prevented from being reduced, and the safety performance of the battery is ensured. The principle of the corona treatment is to destroy the molecular structure of the polymer on the surface of the diaphragm, thereby causing damage to the mechanical strength of the diaphragm to a certain extent. The absolute ethyl alcohol on the surface can react with plasma in the corona process to generate oxidation or polarization, so that the excessive damage of the plasma to the molecular structure on the surface of the diaphragm is reduced, and the excessive damage to the mechanical strength of the diaphragm is avoided.
Preferably, the condition of the corona treatment is 1 to 1.7 kV.
The preparation method of the diaphragm comprises the following preparation steps: and placing the diaphragm in an environment with the dew point of-60 to-40 ℃ for 72 to 120 hours to prepare the electrostatic diaphragm.
The principle is similar to that in dry weather, static electricity is easily generated when people wear sweaters, the diaphragm is made of non-conductive polymer materials, the moisture content of the diaphragm is reduced continuously when the diaphragm is placed in an environment with a low dew point, accumulated charges can be transferred and transferred by taking water as a medium when the diaphragm is placed in an environment with a certain moisture content, and the charges are accumulated on the surface of the diaphragm and cannot be transferred or transferred to form static electricity when the diaphragm is placed in an extremely low moisture content state.
The lamination process of the diaphragm comprises the following steps:
1) preparing a first unit: placing the positive pole pieces above the diaphragm at equal intervals, performing adsorption connection through electrostatic action, and cutting to form a first unit;
2) preparing a second unit: meanwhile, the negative pole pieces are arranged above the second diaphragm at equal intervals, are connected through electrostatic action and are cut to form a second unit;
3) preparing an electric core: and stacking the first unit and the second unit in sequence to obtain the battery cell structure.
The lamination process method can avoid the formation of small units through a hot pressing mode, greatly improve the infiltration performance of the battery core, shorten the infiltration time and improve the production efficiency of the battery core, and can reduce the internal stress between the diaphragm and the pole piece by separately preparing the units of the anode and the diaphragm and the units of the cathode and the diaphragm, thereby being beneficial to avoiding the unevenness and deformation of the battery core caused by the overlarge internal stress of the small units and difficult release.
Preferably, the equidistant distance is 5-20 mm.
Therefore, the invention has the following beneficial effects:
(1) the invention adopts a diaphragm with stronger static electricity, the diaphragm and an anode (a first unit) and the diaphragm and a cathode (a second unit) are respectively connected together through the electrostatic adsorption effect of the diaphragm, and then the first unit and the second unit are sequentially stacked to form a cell structure;
(2) the invention avoids forming small units by hot pressing, can greatly improve the infiltration performance of the battery cell, shorten the infiltration time and improve the production efficiency of the battery cell;
(3) the electrostatic adsorption can not cause larger internal stress between the diaphragm and the pole piece, and the unit of the anode and the diaphragm and the unit of the cathode and the diaphragm are separately prepared, so that the unevenness and the deformation of the battery cell caused by the large internal stress can be avoided, the reduction of the structural performance of the battery cell is promoted, the battery cell has better electrochemical performance, the preparation process is simple, and the high-quality yield is high.
Detailed Description
The invention is further described with reference to specific embodiments.
Example 1
A membrane having an electrostatic charge of 800V during use of the stack.
The membrane comprises a PE nonwoven membrane.
The preparation method of the diaphragm comprises the following preparation steps: placing the diaphragm in an isolation cavity before lamination and spraying absolute ethyl alcohol; and then carrying out corona treatment on the 1kV plasma, and drying to obtain the membrane with static electricity.
The lamination process of the diaphragm comprises the following steps:
1) preparing a first unit: placing the positive pole pieces above the diaphragm at equal intervals of 5mm, performing adsorption connection through electrostatic action, and cutting to form a first unit;
2) preparing a second unit: meanwhile, the negative pole pieces are arranged above the second diaphragm at equal intervals of 5mm, and are connected through electrostatic action, and a second unit is formed after slitting;
3) preparing an electric core: and stacking the first unit and the second unit in sequence to obtain the battery cell structure.
Example 2
A membrane having an electrostatic magnitude of 1500V when the stack is in use.
The diaphragm is a PE diaphragm.
The preparation method of the diaphragm comprises the following preparation steps: placing the diaphragm in an isolation cavity before lamination and spraying absolute ethyl alcohol; and then carrying out corona treatment on the 1.4kV plasma, and drying to obtain the membrane with static electricity.
The lamination process of the diaphragm comprises the following steps:
1) preparing a first unit: placing the positive pole pieces above the diaphragm at equal intervals of 8mm, performing adsorption connection through electrostatic action, and cutting to form a first unit;
2) preparing a second unit: meanwhile, the negative pole pieces are arranged above the second diaphragm at equal intervals of 8mm, and are connected through electrostatic action, and a second unit is formed after slitting;
3) preparing an electric core: and stacking the first unit and the second unit in sequence to obtain the battery cell structure.
Example 3
A membrane having an electrostatic charge of 1800V when the membrane is in use in a stack.
The diaphragm is a PP diaphragm.
The preparation method of the diaphragm comprises the following preparation steps: placing the diaphragm in an isolation cavity before lamination and spraying absolute ethyl alcohol; and then carrying out corona treatment on the 1.7kV plasma, and drying to obtain the membrane with static electricity.
The lamination process of the diaphragm comprises the following steps:
1) preparing a first unit: placing the positive pole pieces above the diaphragm at equal intervals of 10mm, performing adsorption connection through electrostatic action, and cutting to form a first unit;
2) preparing a second unit: meanwhile, the negative pole pieces are arranged above the second diaphragm at equal intervals of 10mm, are connected through electrostatic action and are cut to form a second unit;
3) preparing an electric core: and stacking the first unit and the second unit in sequence to obtain the battery cell structure.
Example 4
A membrane having an electrostatic magnitude of 2000V when the membrane is in use.
The membrane is a PVDF membrane.
The preparation method of the diaphragm comprises the following preparation steps: and (3) placing the diaphragm in an environment with a dew point of-60 ℃ for 72 hours to prepare the electrostatic diaphragm.
The lamination process of the diaphragm comprises the following steps:
1) preparing a first unit: placing the positive pole piece above the diaphragm at an equal interval of 14mm, performing adsorption connection through electrostatic action, and cutting to form a first unit;
2) preparing a second unit: meanwhile, the negative pole pieces are arranged above the second diaphragm at equal intervals of 14mm, and are connected through electrostatic action, and a second unit is formed after slitting;
3) preparing an electric core: and stacking the first unit and the second unit in sequence to obtain the battery cell structure.
Example 5
A membrane having a static charge of 2500V when the stack is in use.
The membrane is a PVDF-HFP membrane.
The preparation method of the diaphragm comprises the following preparation steps: and (3) placing the diaphragm in an environment with a dew point of-50 ℃ for 95h to prepare the electrostatic diaphragm.
The lamination process of the diaphragm comprises the following steps:
1) preparing a first unit: placing the positive pole piece above the diaphragm at equal intervals of 18mm, performing adsorption connection through electrostatic action, and cutting to form a first unit;
2) preparing a second unit: meanwhile, the negative pole pieces are arranged above the second diaphragm at equal intervals of 18mm, are connected through electrostatic action and are cut to form a second unit;
3) preparing an electric core: and stacking the first unit and the second unit in sequence to obtain the battery cell structure.
Example 6
A membrane having an electrostatic charge of 3000V when the stack is in use.
The diaphragm is coated with an aluminum oxide diaphragm.
The preparation method of the diaphragm comprises the following preparation steps: and (3) placing the diaphragm in an environment with a dew point of-40 ℃ for 120h to prepare the electrostatic diaphragm.
The lamination process of the diaphragm comprises the following steps:
1) preparing a first unit: placing the positive pole pieces above the diaphragm at equal intervals of 20mm, performing adsorption connection through electrostatic action, and cutting to form a first unit;
2) preparing a second unit: meanwhile, the negative pole pieces are arranged above the second diaphragm at equal intervals of 20mm, are connected through electrostatic action and are cut to form a second unit;
3) preparing an electric core: and stacking the first unit and the second unit in sequence to obtain the battery cell structure.
Comparative example 1
The difference from example 2 is that the magnitude of the static electricity charged to the separator was 500V.
Comparative example 2
The difference from example 2 is that the membrane was prepared without spraying with absolute ethanol.
Comparative example 3
The difference from example 2 is that hot pressing is used instead of electrostatic adsorption stacking.
Comparative example 4
The difference from example 5 is that the dew point resting temperature is too low at-70 ℃.
Comparative example 5
The difference from example 5 is that the dew point resting time was too short, 60 h.
Comparative example 6
The difference from example 5 is that the magnitude of static electricity charged to the separator was 3500V.
The results of the tests on the finished products obtained in examples 1 to 6 and comparative examples 1 to 6 are shown in Table 1.
The positive electrode of the batteries in the examples and comparative examples was the ternary material NMC811, the negative electrode was graphite, and the theoretical capacity was 58(1/3C) Ah.
TABLE 1 relevant Performance indices of the finished products in the examples and comparative examples
Conclusion analysis:
the lithium battery cell structure with excellent performance can be prepared in the embodiments 1-6, and the structure has good wettability and good smoothness, so that the material has good electrochemical performance and long service life.
For the relevant data of comparative examples 1 to 6, comparative example 1 in comparative example 1 is different from example 2 in that the magnitude of static electricity charged to the separator is 500V, the yield is extremely low, only 5%, and the cause of performance degradation is analyzed: the diaphragm and the pole piece can not be effectively compounded, and the binding force between the diaphragm and the pole piece is poor, so that the yield is extremely low;
the difference between the comparative example 2 and the example 2 is that the preparation process of the diaphragm does not adopt absolute ethyl alcohol spraying, the yield is obviously reduced, the performance is reduced, the adhesion between the diaphragm and the pole piece is still weak, and the lamination process is easy to have the situation of infirm compounding, so the yield is lower;
the difference between the comparative example 3 and the example 2 is that the hot pressing replaces the superposition of electrostatic adsorption, the yield is obviously reduced from 97.5 percent to 50 percent, because the anode, the cathode and the diaphragm are seriously deformed and the yield is extremely low after the hot pressing causes the compounding of the anode, the cathode and the diaphragm; and the adhesive force between the pole piece and the diaphragm interface is too large, so that the interface electrolyte is difficult to soak, and the soaking time is long. The internal resistance of the battery, namely DCR is remarkably increased, the capacity is difficult to effectively exert, and the internal resistance is only 35.7 Ah;
comparative example 4 is different from example 5 in that the dew point resting temperature was too low at-70 c, and the battery yield decreased to only 71%. The battery capacity dropped to 54Ah and the DCR increased significantly. The main reason is that the dew point temperature is too low, the static electricity of the diaphragm is too large, dust and impurities are easily adsorbed in the lamination process, the yield is reduced, the internal resistance of the battery is increased due to the existence of the impurities, the side reaction is increased, and the capacity is reduced;
the difference between the comparative example 5 and the example 5 is that the dew point standing time is too short, namely 60 hours, the battery yield is reduced from 99% to 80%, the capacity is reduced from 58Ah to 53Ah, the DCR is increased from 1.75 to 2.5, and the reason is mainly that the standing time is too short, enough static electricity cannot be formed on the surface of the diaphragm, the composite effect of the pole piece and the diaphragm is influenced, and the yield is reduced. Meanwhile, the time is too short, the water content of the diaphragm is higher, so that the water content in the battery cell is higher, and the side reaction of the battery in the formation and grading processes is serious, so that the DCR is remarkably increased, and the capacity is reduced;
comparative example 6 is different from example 5 in that the magnitude of static electricity charged to the separator was 3500V, the battery yield was reduced from 100% to 60%, the capacity was reduced from 58Ah to 49Ah, and the DCR was increased from 1.7 to 2.7. The reason is that the diaphragm is easy to absorb a large amount of impurity dust in the lamination process due to overlarge static electricity, so that the yield is reduced. Meanwhile, the impurity dust causes side reactions inside the battery, increases the internal resistance of the battery, and causes a drop in capacity.
As can be seen from the data of examples 1 to 6 and comparative examples 1 to 6, only the solutions within the scope of the claims of the present invention can satisfy the above requirements in all aspects, and an optimized solution can be obtained, and a lithium battery cell structure with optimal performance can be obtained. The change of the mixture ratio, the replacement/addition/subtraction of raw materials or the change of the feeding sequence can bring corresponding negative effects.
The raw materials and equipment used in the invention are common raw materials and equipment in the field if not specified; the methods used in the present invention are conventional in the art unless otherwise specified.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, alterations and equivalents of the above embodiments according to the technical spirit of the present invention are still within the protection scope of the technical solution of the present invention.
Claims (10)
1. A diaphragm is characterized in that the static electricity of the diaphragm in use of a lamination is 800-3000V.
2. The separator of claim 1, wherein the separator comprises one of a PE separator, a PP separator, a multilayer separator of any combination of PE and PP, a non-woven separator, and a coated separator.
3. The separator according to claim 2, wherein the matrix material of the nonwoven fabric separator comprises at least one of PI, PA, PVDF-HFP, PAN, cellulose, PE, PP, and the like.
4. The separator of claim 2, wherein the coating layer of the coated separator comprises at least one of ceramic particles, aramid, PVDF-HFP, PAN, PVA, PMMA, and derivatives thereof.
5. The separator according to claim 4, wherein said ceramic particles comprise at least one of alumina, boehmite, barium sulfate, magnesium sulfate, and silica.
6. A method for preparing a separator as claimed in any one of claims 1 to 5, characterized by comprising the following preparation steps: spraying absolute ethyl alcohol on the diaphragm before lamination; and then carrying out corona treatment and drying to obtain the electrostatic diaphragm.
7. The method for producing a separator according to claim 6, wherein the condition of the corona treatment is 1 to 1.7 kV.
8. A method for preparing a separator as claimed in any one of claims 1 to 5, characterized by comprising the following preparation steps: and placing the diaphragm in an environment with the dew point of-60 to-40 ℃ for 72-120h to prepare the electrostatic diaphragm.
9. A lamination process for membranes according to claim 1 wherein said lamination process is:
1) preparing a first unit: placing the positive pole pieces above the diaphragm at equal intervals, performing adsorption connection through electrostatic action, and cutting to form a first unit;
2) preparing a second unit: meanwhile, the negative pole pieces are arranged above the second diaphragm at equal intervals, are connected through electrostatic action and are cut to form a second unit;
3) preparing an electric core: and stacking the first unit and the second unit in sequence to obtain the battery cell structure.
10. Process for the lamination of membranes according to claim 8, wherein said equidistant distance is comprised between 5 and 20 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
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