CN219658917U - Separator and battery - Google Patents
Separator and battery Download PDFInfo
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- CN219658917U CN219658917U CN202321219714.2U CN202321219714U CN219658917U CN 219658917 U CN219658917 U CN 219658917U CN 202321219714 U CN202321219714 U CN 202321219714U CN 219658917 U CN219658917 U CN 219658917U
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- heat
- material layer
- resistant material
- separator
- base film
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- 229910010293 ceramic material Inorganic materials 0.000 description 9
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- 239000002002 slurry Substances 0.000 description 9
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- 239000004698 Polyethylene Substances 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 239000007773 negative electrode material Substances 0.000 description 7
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- 239000002270 dispersing agent Substances 0.000 description 4
- 239000003792 electrolyte Substances 0.000 description 4
- 230000020169 heat generation Effects 0.000 description 4
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 4
- 239000011819 refractory material Substances 0.000 description 4
- 239000003381 stabilizer Substances 0.000 description 4
- 239000001577 tetrasodium phosphonato phosphate Substances 0.000 description 4
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 3
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- 239000002033 PVDF binder Substances 0.000 description 3
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 description 3
- 239000000853 adhesive Substances 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 229910001593 boehmite Inorganic materials 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 239000011889 copper foil Substances 0.000 description 3
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- 229910001416 lithium ion Inorganic materials 0.000 description 3
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- FQENQNTWSFEDLI-UHFFFAOYSA-J sodium diphosphate Chemical compound [Na+].[Na+].[Na+].[Na+].[O-]P([O-])(=O)OP([O-])([O-])=O FQENQNTWSFEDLI-UHFFFAOYSA-J 0.000 description 3
- 235000019333 sodium laurylsulphate Nutrition 0.000 description 3
- 229940048086 sodium pyrophosphate Drugs 0.000 description 3
- 229920003048 styrene butadiene rubber Polymers 0.000 description 3
- 235000019818 tetrasodium diphosphate Nutrition 0.000 description 3
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 description 2
- 239000004642 Polyimide Substances 0.000 description 2
- 239000004793 Polystyrene Substances 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 239000011267 electrode slurry Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
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- 235000019832 sodium triphosphate Nutrition 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 108010010803 Gelatin Proteins 0.000 description 1
- IGFHQQFPSIBGKE-UHFFFAOYSA-N Nonylphenol Natural products CCCCCCCCCC1=CC=C(O)C=C1 IGFHQQFPSIBGKE-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- MCMNRKCIXSYSNV-UHFFFAOYSA-N ZrO2 Inorganic materials O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 1
- KFDQGLPGKXUTMZ-UHFFFAOYSA-N [Mn].[Co].[Ni] Chemical compound [Mn].[Co].[Ni] KFDQGLPGKXUTMZ-UHFFFAOYSA-N 0.000 description 1
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- SNQQPOLDUKLAAF-UHFFFAOYSA-N nonylphenol Chemical compound CCCCCCCCCC1=CC=CC=C1O SNQQPOLDUKLAAF-UHFFFAOYSA-N 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 description 1
- 229920000058 polyacrylate Polymers 0.000 description 1
- 229920005646 polycarboxylate Polymers 0.000 description 1
- 229940051841 polyoxyethylene ether Drugs 0.000 description 1
- 229920000056 polyoxyethylene ether Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
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- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
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- 239000002994 raw material Substances 0.000 description 1
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- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
- 235000019982 sodium hexametaphosphate Nutrition 0.000 description 1
- GCLGEJMYGQKIIW-UHFFFAOYSA-H sodium hexametaphosphate Chemical compound [Na]OP1(=O)OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])O1 GCLGEJMYGQKIIW-UHFFFAOYSA-H 0.000 description 1
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 description 1
- AGVNDXHAPPQIMH-UHFFFAOYSA-M sodium;3-butylnaphthalene-1-sulfonate Chemical compound [Na+].C1=CC=CC2=CC(CCCC)=CC(S([O-])(=O)=O)=C21 AGVNDXHAPPQIMH-UHFFFAOYSA-M 0.000 description 1
- 230000008093 supporting effect Effects 0.000 description 1
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- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
Landscapes
- Cell Separators (AREA)
Abstract
The utility model provides a separator and a battery, wherein the base film comprises a first surface and a second surface which are oppositely arranged along the thickness direction of the base film; the first heat-resistant material layer is arranged on at least one side of the first surface and the second surface, and comprises at least one strip-shaped structure, and at least one strip-shaped structure is positioned on the lug side of the pole piece; and the second heat-resistant material layer is arranged on at least one side of the base film close to the first surface and the second surface, covers the surface of the base film, and is positioned between the first heat-resistant material layer and the base film when the first heat-resistant material layer and the second heat-resistant material layer are positioned on the same side surface of the diaphragm. According to the utility model, the first heat-resistant material layer and the second heat-resistant material layer are matched, so that the high temperature resistance of the diaphragm is effectively improved, and thermal runaway caused by overcharging or short circuit of the battery is avoided.
Description
Technical Field
The utility model relates to the technical field of batteries, in particular to a diaphragm and a battery.
Background
With the rapid development of lithium ion batteries and the higher and higher requirements of the user end on the battery performance, the safety problem of the lithium ion batteries becomes increasingly prominent, and overcharge and external short circuit are recognized as difficult-to-pass test items in common safety test methods.
There are many safety strategies for improving overcharge and external short circuits in the conventional technology, such as: the diaphragm and the pole piece are coated with special coatings with serious gas production under high temperature state, or a fusing strategy is adopted, namely: the current collector or the tab is fused at a high temperature to further block further heat generation, but the above strategies can influence the battery performance to a certain extent, so that it is very important to find a more effective and practical safety improvement strategy. Moreover, the battery cells after the two safety tests have the common characteristics that: after testing, the diaphragm at the lug side of the battery cell has obvious thermal contraction, and is easy to cause short circuit of the anode and the cathode, thereby causing thermal runaway.
Therefore, a technical solution capable of reducing the phenomena of positive and negative electrode short circuit and thermal runaway to improve the safety performance of the battery is needed.
Disclosure of Invention
Based on this, it is necessary to provide a separator and a battery in which the strip-like structure in the first heat-resistant material layer improves the heat resistance of the separator, and the second heat-resistant material layer coats the surface of the separator to secure the shape of the separator, thereby avoiding the problem of thermal runaway due to thermal shrinkage of the separator and improving the safety of the battery.
In a first aspect, the present utility model provides a separator comprising:
a base film including a first surface and a second surface disposed opposite to each other in a thickness direction thereof;
the first heat-resistant material layer is arranged on at least one side of the first surface and the second surface, and comprises at least one strip-shaped structure, and at least one strip-shaped structure is positioned on the tab side of the pole piece;
the second heat-resistant material layer is arranged on at least one side of the first surface and the second surface, the second heat-resistant material layer covers the surface of the base film, and when the first heat-resistant material layer and the second heat-resistant material layer are positioned on the same side surface of the base film, the second heat-resistant material layer is positioned between the first heat-resistant material layer and the base film.
In some embodiments, in the first heat-resistant material layer, the strip-shaped structures include at least two, and at least two of the strip-shaped structures are arranged at intervals.
In some embodiments, the first surface and the second surface are both provided with a first heat-resistant material layer, and the strip-shaped structures are staggered or oppositely arranged in the first heat-resistant material layer of the first surface and the second surface.
In some embodiments, the width of the strip-like structure is 10mm to 30mm.
In some embodiments, the base film has a thickness of 2 μm to 40 μm.
In some embodiments, the first heat resistant material layer has a thickness of 1 μm to 300 μm.
In some embodiments, the second heat resistant material layer has a thickness of 0 to 10 μm.
In some embodiments, the first refractory material layer comprises a ceramic refractory layer.
In some embodiments, the second refractory material layer comprises a ceramic refractory layer or a rubberized refractory layer.
In a second aspect, the present utility model provides a battery comprising a positive electrode, a separator and a negative electrode, the separator employing the separator according to the first aspect.
In some embodiments, the positive electrode and the negative electrode are alternately stacked, and the separator is disposed between adjacent positive and negative electrodes;
the negative electrode is disposed on a side of the separator having the first heat-resistant material layer.
The utility model has the beneficial effects that:
according to the utility model, the first heat-resistant material layer with the strip-shaped structure is arranged on the surface of the diaphragm, so that the local high temperature resistance is improved, the shape of the diaphragm is further maintained by the second heat-resistant material layer, the thermal shrinkage of the diaphragm in a high temperature state is effectively avoided, the original structure and shape of the battery core are further maintained, and the safety of the battery is effectively improved.
Drawings
FIG. 1 is a schematic side view of the separator provided in example 1 of the present utility model, wherein 1a is a base film; 2 a-a second heat resistant material layer; 3 a-a first heat resistant material layer.
Fig. 2 is a schematic top view of the separator provided in embodiment 1 of the present utility model.
FIG. 3 is a schematic side view of the separator provided in example 2 of the present utility model, wherein 1b is a base film; 2 b-a second heat resistant material layer; 3 b-a first heat resistant material layer.
FIG. 4 is a schematic side view of the separator provided in example 3 of the present utility model, wherein the 1 c-base film; 2 c-a second heat resistant material layer; 3 c-a first heat resistant material layer.
FIG. 5 is a schematic side view of the separator provided in example 4 of the present utility model, wherein the 1 d-base film; 2 d-a second heat resistant material layer; 3 d-a first heat resistant material layer.
FIG. 6 is a schematic side view of the separator provided in example 5 of the present utility model, wherein the 1 e-base film; 2 e-a second heat resistant material layer; 3 e-a first heat resistant material layer.
Detailed Description
In order that the utility model may be readily understood, a more complete description of the utility model will be rendered by reference to the appended drawings. Preferred embodiments of the present utility model are shown in the drawings. This utility model may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It is to be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate or are based on the orientation or positional relationship shown in the drawings, merely to facilitate describing the present utility model and simplify the description, and do not indicate or imply that the devices or elements being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present utility model.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present utility model, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the safety test process of the battery, the test items of overcharge and external short circuit are difficult to pass, so that the overcharge and external short circuit of the battery are improved in the conventional technology, and the improvement method comprises the following steps: (1) Coating a coating capable of generating gas at a high temperature on the diaphragm and the pole piece in a uniform coating mode, so as to block battery reaction and further block heat generation; (2) And a mode of fusing the current collector or the tab at high temperature is adopted, and the fusing strategy is utilized to block further heat generation of the battery. However, the method has an influence on the performance of the battery, and after the battery is subjected to the charging and external short-circuit test, the diaphragm at the lug side of the battery cell has obvious thermal shrinkage, so that the thermal runaway caused by the short circuit of the anode and the cathode is easy to cause. The diaphragm adopts the combination of the first coating layer and the second coating layer, and the second coating layer adopts the heat-resistant layer arranged at intervals, so that the local high temperature resistance of the diaphragm is improved, the thermal shrinkage of the diaphragm is reduced, and the safety performance of the battery is improved.
A first aspect of the present utility model provides a separator comprising:
a base film including a first surface and a second surface disposed opposite to each other in a thickness direction thereof;
the first heat-resistant material layer is arranged on at least one side of the first surface and the second surface, and comprises at least one strip-shaped structure, and at least one strip-shaped structure is positioned on the tab side of the pole piece;
the second heat-resistant material layer is arranged on at least one side of the first surface and the second surface, the second heat-resistant material layer covers the surface of the base film, and when the first heat-resistant material layer and the second heat-resistant material layer are positioned on the same side surface of the base film, the second heat-resistant material layer is positioned between the first heat-resistant material layer and the base film.
According to the utility model, the first heat-resistant material layer with the strip-shaped structure is arranged on the surface of the diaphragm, so that the local high temperature resistance is improved, the shape of the diaphragm is further maintained by the second heat-resistant material layer, the thermal shrinkage of the diaphragm in a high temperature state is effectively avoided, the original structure and shape of the battery core are further maintained, the problem of thermal runaway caused by short circuit of the anode and the cathode is avoided, and the safety of the battery is effectively improved.
In addition, the first heat-resistant material layer comprises a plurality of strip-shaped structures which are arranged at intervals, and grooves with a liquid-retaining function are formed between two adjacent strip-shaped structures, so that the liquid-retaining capacity of the battery is improved, and the service life of the battery is prolonged.
It should be noted that, the heat-resistant material layer in the present utility model refers to a material layer with high temperature resistance, and those skilled in the art can reasonably select according to practical use requirements. Further, "first" and "second" in the first heat-resistant material layer and the second heat-resistant material layer in the present utility model are used only for distinguishing the names of the two layers, and the material used for the first heat-resistant material layer may be the same as or different from the material used for the second heat-resistant material layer.
In some embodiments, at least one strip structure in the first heat resistant material layer is located at a tab side of the battery. For example, the first heat-resistant material layer includes a strip-like structure disposed opposite the positive electrode tab and opposite the negative electrode tab.
In some embodiments, in the first heat-resistant material layer, the strip-shaped structures include at least two, and at least two of the strip-shaped structures are arranged at intervals. Optionally, the length direction of the strip-shaped structure is parallel to the length direction of the base film, and when the strip-shaped structure includes a plurality of strip-shaped structures, the strip-shaped structures are arranged at intervals along the width direction of the base film. In the present utility model, the longitudinal direction of the separator means the direction of the longer side of the base film. Further, taking a wound cell as an example, the length direction generally refers to the winding direction.
In some embodiments, the first surface and the second surface are both provided with a first heat-resistant material layer, and the strip-shaped structures are staggered or oppositely arranged in the first heat-resistant material layer of the first surface and the second surface. Wherein, the opposite arrangement means that each strip structure on the first surface corresponds to each strip structure on the second surface one by one and is arranged at two sides of the base film oppositely; the staggered arrangement means that the strip-shaped structures are staggered on both sides of the base film.
In some embodiments, the width of the strip-like structure is 10mm to 30mm, for example 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm or 30mm.
It should be noted that, in the present utility model, the spacing distance between two adjacent strip structures is not specifically limited and is not specifically limited, and those skilled in the art may reasonably select the spacing distances according to actual use requirements, for example, the spacing distances between two adjacent strip structures may be the same or different.
In some embodiments, the base film has a thickness of 2 μm to 40 μm, for example, 2 μm, 4 μm, 8 μm, 12 μm, 16 μm, 20 μm, 24 μm, 28 μm, 32 μm, 36 μm, or 40 μm.
In some embodiments, the thickness of the first heat resistant material layer is 1 μm to 300 μm, for example 1 μm, 2 μm, 10 μm, 20 μm, 30 μm, 60 μm, 90 μm, 120 μm, 150 μm, 180 μm, 210 μm, 240 μm, 270 μm or 300 μm, preferably 2 μm to 140 μm.
It should be noted that the size of each strip structure in the first heat-resistant material layer is not specifically required or limited, and those skilled in the art can reasonably select the size of each strip structure according to the use requirement of the actual battery cell. For example, the width, thickness, etc. of each stripe structure may be the same or different.
In some embodiments, the thickness of the second heat resistant material layer is 0 to 10 μm, for example 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, preferably 0 to 3 μm.
In some embodiments, the first refractory material layer comprises a ceramic refractory layer.
According to the utility model, the ceramic heat-resistant layer is used as the first heat-resistant material layer, and the ceramic material can improve the high temperature resistance, heat shrinkage resistance and puncture strength of the diaphragm, so that the safety performance of the battery is improved. In addition, the ceramic material also has good infiltration and liquid absorption and retention capacity, can prolong the service life of the battery, and can reduce the occurrence of the problem of battery swelling.
In some embodiments, the ceramic heat resistant layer has a porous structure. The ceramic heat-resistant layer has a porous structure, so that the electrolyte holding capacity of the battery can be further improved, and the service life and the cycle performance of the battery are improved.
In some embodiments, the second refractory material layer comprises a ceramic refractory layer or a rubberized refractory layer.
According to the utility model, the ceramic heat-resistant layer or the glue-coated heat-resistant layer is adopted as the second heat-resistant material layer, when the glue-coated heat-resistant layer is adopted, the contact capability of the diaphragm and the pole piece is improved, the adhesive property of the diaphragm can be improved, and in a high temperature state, after the close part of the glue-coated heat-resistant layer is melted, a good coating effect can be formed on the strip-shaped structure in the first heat-resistant material layer, so that the problems of cracking of the strip-shaped structure or direct melting shrinkage of the diaphragm are avoided; when the ceramic heat-resistant layer is adopted, the high temperature resistance of the diaphragm can be further enhanced, a certain structural supporting effect can be achieved, and the thermal shrinkage of the diaphragm is further reduced.
The material of the rubberized heat-resistant layer comprises at least one of polyvinylidene fluoride, acrylic acid, styrene-butadiene rubber, polystyrene and polyacrylate, and is preferably polyvinylidene fluoride, acrylic acid, styrene-butadiene rubber or polystyrene.
In some embodiments, the material of the base film comprises at least one of polyethylene, polypropylene, and polyimide. For example, the base film may be a polyethylene base film, a polypropylene base film, or a polyimide base film. The separator according to the present utility model may have a single-layer structure or a multilayer structure, and for example, the base film may have a double-layer structure of a polyethylene base film and a polypropylene base film.
Optionally, the thickness of the membrane is 2 μm to 40 μm. For example 2 μm, 4 μm, 8 μm, 12 μm, 16 μm, 20 μm, 24 μm, 28 μm, 32 μm, 36 μm or 40 μm.
In the present utility model, the thickness of the separator refers to the sum of the base film thickness, the total thickness of the first heat-resistant material layer, and the total thickness of the second heat-resistant material layer. The total thickness of the first heat-resistant material layer refers to the total thickness of the first heat-resistant material layer calculated according to the number of layers of the first heat-resistant material layer in the diaphragm, for example, the first heat-resistant material layers are respectively arranged at two sides of the base film, namely, the diaphragm comprises two layers of the first heat-resistant material layers, so that the thickness of the first heat-resistant material layer is the sum of the thicknesses of the first heat-resistant material layers at two sides of the base film; if the diaphragm is provided with the first heat-resistant material layer on one side surface of the base film only, the total thickness of the first heat-resistant material layer is the thickness of one layer of the first heat-resistant material layer; the total thickness of the second heat-resistant material layer is calculated in a similar manner to the total thickness of the first heat-resistant material layer.
In some embodiments, the ceramic heat-resistant layer may be a ceramic layer formed only by ceramic materials, or may be a ceramic slurry formed by mixing ceramic material powder with an adhesive or the like, wherein the ceramic heat-resistant layer is formed after the ceramic slurry is coated, and the mass ratio of the ceramic material powder is 50% -98% after the ceramic material powder is mixed with the adhesive.
In some embodiments, the ceramic slurry further comprises at least one of a stabilizer, a dispersant, and a sizing agent.
The utility model has no specific requirement or special limitation on the selection of each material in the ceramic slurry, and the materials such as ceramic materials, adhesives, stabilizers, dispersants, impregnating compounds and the like can be reasonably selected according to actual needs by a person skilled in the art, so that the ceramic heat-resistant layer required by the utility model can be formed.
Optionally, the stabilizer comprises at least one of gelatin, methyl cellulose, carboxymethyl cellulose, sodium polyacrylate, polyethylene oxide and polyvinyl alcohol, preferably methyl cellulose or carboxymethyl cellulose, and the stabilizer accounts for 0.05-5% of the mass of the ceramic slurry.
Optionally, the dispersing agent comprises at least one of sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, alkylaryl phosphate, alkylbenzene sulfonate and polycarboxylate, preferably sodium pyrophosphate or sodium tripolyphosphate, and the dispersing agent accounts for 0.02-2% of the mass of the ceramic slurry.
Optionally, the impregnating compound comprises at least one of sodium dodecyl sulfate, fatty alcohol, ethylene oxide, butyl naphthalene sulfonate sodium salt and nonylphenol polyoxyethylene ether, preferably sodium dodecyl sulfate, fatty alcohol or ethylene oxide, and the impregnating compound accounts for 0.02-2% of the mass of the ceramic slurry.
In some embodiments, the ceramic material comprises at least one of nano-alumina, nano-silica, nano-boehmite, nano-titania, and nano-zirconia, preferably the ceramic material comprises nano-alumina or nano-boehmite.
By way of example and not limitation, there is provided a method of preparing the above-described separator comprising:
coating a slurry on at least one side surface of the base film and forming a second heat-resistant material layer;
and coating slurry on at least one side surface of the base film with the second heat-resistant material layer, and forming a first heat-resistant material layer with a strip-shaped structure which is arranged at intervals, wherein when the first heat-resistant material layer and the second heat-resistant material layer are arranged on the same side surface of the base film, the second heat-resistant material layer is positioned between the first heat-resistant material layer and the base film.
In a second aspect, the present utility model provides a battery comprising a positive electrode, a separator and a negative electrode, the separator employing the separator according to the first aspect.
In some embodiments, the battery is a lithium ion battery, including a housing impregnated with an electrolyte, and an electrical cell immersed in the electrolyte. The battery cell can be a winding battery cell or a laminated battery cell, the battery cell comprises positive electrodes and negative electrodes which are alternately laminated, and the separator is arranged between the adjacent positive electrodes and negative electrodes; the positive electrode comprises a positive electrode current collector and a positive electrode material layer arranged on at least one side surface of the positive electrode current collector, the positive electrode current collector comprises an aluminum foil, and the positive electrode material in the positive electrode material layer comprises a lithium iron phosphate material or a nickel cobalt manganese ternary material; the negative electrode comprises a negative electrode current collector and a negative electrode material layer arranged on at least one side surface of the negative electrode current collector, the negative electrode current collector comprises copper foil, and the negative electrode material in the negative electrode material layer comprises graphite material or silicon negative electrode material.
In some embodiments, the positive electrode and the negative electrode are alternately stacked, and the separator is disposed between adjacent positive electrode and negative electrode;
the negative electrode is disposed on a side of the separator having the first heat-resistant material layer.
In the following examples, the ceramic heat-resistant layer was formed by coating a ceramic slurry comprising nano-boehmite, acrylic acid, carboxymethyl cellulose, sodium pyrophosphate and sodium dodecyl sulfate in a mass ratio of 94:2:2:1.5:0.5, followed by drying.
The rubberized heat-resistant layer is formed by coating glue solution mixed by styrene-butadiene rubber and carboxymethyl cellulose in a mass ratio of 95:5.
The raw materials in the following examples were commercially available products.
Example 1
The present embodiment provides a diaphragm, as shown in fig. 1 and 2, including a base film 1a, a second heat-resistant material layer 2a and a first heat-resistant material layer 3a, the two side surfaces of the base film 1a are both provided with the second heat-resistant material layer 2a, the first heat-resistant material layer 3a is respectively disposed on one side surface of the second heat-resistant material layer 2a far away from the base film 1a, and the first heat-resistant material layer 3a includes a strip structure and is located at a pole piece mounting tab.
Wherein, the base film 1a adopts a polypropylene base film with the thickness of 20 mu m; the second heat-resistant material layer 2a is a rubberized heat-resistant layer with a thickness of 5 μm; the first heat-resistant material layer 3a was a ceramic heat-resistant layer and the width of the stripe structure was 10mm, and the thickness of the first heat-resistant material layer 3a was 100 μm.
Example 2
The present embodiment provides a separator, as shown in fig. 3, including a base film 1b, a second heat-resistant material layer 2b and a first heat-resistant material layer 3b, one side surface of the base film 1b is provided with the second heat-resistant material layer 2b, one side surface of the base film 1b away from the second heat-resistant material layer 2b is provided with the first heat-resistant material layer 3b, the first heat-resistant material layer 3b includes two strip-shaped structures arranged at intervals, and along the width direction, the two strip-shaped structures are respectively located at two ends of the surface of the separator.
Wherein the base film 1b is a polyethylene-based film having a thickness of 5 μm; the second heat-resistant material layer 2b is a ceramic heat-resistant layer having a thickness of 10 μm; the first heat-resistant material layer 3b was a ceramic heat-resistant layer, the width of the stripe structure was 30mm, and the thickness of the first heat-resistant material layer 3b was 300 μm.
Example 3
The present embodiment provides a diaphragm, as shown in fig. 4, including a base film 1c, a second heat-resistant material layer 2c and a first heat-resistant material layer 3c, the two side surfaces of the base film 1c are both provided with the second heat-resistant material layer 2c, the surface of the second heat-resistant material layer 2c is provided with the first heat-resistant material layer 3c, the first heat-resistant material layer 3c is a strip structure, the strip structure is located at the end of the diaphragm along the width direction, and the strip structures on the two side surfaces of the diaphragm are respectively located at different ends.
Wherein, the base film 1c adopts a polypropylene base film with the thickness of 30 mu m; the second heat-resistant material layer 2c is a glue-coated heat-resistant layer with the thickness of 5 mu m; the first heat-resistant material layer 3c was a ceramic heat-resistant layer, the width of the stripe structure was 20mm, and the thickness of the first heat-resistant material layer 3c was 100 μm.
Example 4
The present embodiment provides a separator, as shown in fig. 5, including a base film 1d, a second heat-resistant material layer 2d and a first heat-resistant material layer 3d, wherein one side surface of the base film 1d is sequentially laminated with the second heat-resistant material layer 2d and the first heat-resistant material layer 3d, the first heat-resistant material layer 3d includes two strip structures arranged at intervals, and the two strip structures are respectively located at two ends of the separator in the width direction.
Wherein, the base film 1d is a polyethylene-based film with a thickness of 40 μm; the second heat-resistant material layer 2d is a rubberized heat-resistant layer with a thickness of 5 μm; the first heat-resistant material layer 3d was a ceramic heat-resistant layer, the width of the stripe structure was 20mm, and the thickness of the first heat-resistant material layer 3d was 2 μm.
Example 5
The present embodiment provides a diaphragm, as shown in fig. 6, including a base film 1e, a second heat-resistant material layer 2e and a first heat-resistant material layer 3e, wherein one side surface of the base film 1e is provided with the second heat-resistant material layer 2e, the other side surface is provided with the first heat-resistant material layer 3e, the surface of the second heat-resistant material layer 2e far away from the base film 1e is also provided with a layer of the first heat-resistant material layer 3e, the first heat-resistant material layer 3e on one side surface includes three strip structures arranged at intervals, and the three strip structures are respectively located at two ends and a middle position of the diaphragm; the first heat-resistant material layer 3e of the other side surface includes a strip-like structure located at the end of the separator.
Wherein the base film 1e is a polyethylene-based film having a thickness of 16 μm; the second heat-resistant material layer 2e is a rubberized heat-resistant layer with a thickness of 1 μm; the first heat-resistant material layer 3e was a ceramic heat-resistant layer, the width of the stripe structure was 20mm, and the thickness of the second heat-resistant material layer 2e was 2 μm.
Example 6
The only difference compared to the separator provided in example 5 is that the first heat-resistant material layer was replaced with a rubberized heat-resistant layer.
Example 7
The only difference compared to the separator provided in example 5 is that the second heat-resistant material layer is a ceramic heat-resistant layer, and the ceramic heat-resistant layer in the first heat-resistant material layer is replaced with a rubberized heat-resistant layer.
Comparative example 1
The polyethylene-based film having a thickness of 16 μm in example 5 was used directly as a separator.
Comparative example 2
The separator differs from that provided in example 5 only in that the first heat-resistant material layer is not provided.
Comparative example 3
The separator differs from that provided in example 5 only in that the second heat-resistant material layer is not provided.
Batteries were fabricated using the separators of the above examples and comparative examples, the width of the separator being 120mm, and the fabrication method comprising:
and (3) a positive electrode: the positive electrode material layers are arranged on the surfaces of two sides of the aluminum foil, the positive electrode material layers are formed after being coated by positive electrode slurry, and the positive electrode formula is 96% lithium iron phosphate: 2% PVDF:2% SP, aluminum foil thickness of 12 μm, positive electrode material layer thickness of 60 μm;
and (3) a negative electrode: negative electrode material layers are arranged on the surfaces of two sides of the copper foil, the negative electrode material layers are formed after being coated with negative electrode slurry, and the negative electrode formula is 95% graphite: 2% sbr:2% SP:1% CMC, copper foil thickness of 8 μm, negative electrode material layer thickness of 40 μm;
the positive electrode, the separator, and the negative electrode were laminated, wherein the separator having the first heat-resistant material layer was provided with the negative electrode on the side having the first heat-resistant material layer, and a battery cell having a capacity of 20Ah was produced.
Test case
Overcharging test was performed on the prepared battery cell by using GB/T36276-2018 to obtain the battery cell passing rate of the diaphragms in each example and comparative example, and the test results are shown in Table 1.
TABLE 1
| Numbering device | Pass rate of |
| Example 1 | 100％ |
| Example 2 | 100％ |
| Example 3 | 100％ |
| Example 4 | 100％ |
| Example 5 | 100％ |
| Example 6 | 90％ |
| Example 7 | 90％ |
| Comparative example 1 | 20％ |
| Comparative example 2 | 50％ |
| Comparative example 3 | 90％ |
As can be seen from the table above:
according to the utility model, the combination of the first coating layer and the second coating layer is adopted in the utility model, so that the safety performance of the diaphragm is effectively improved, and the passing rate in the test process is 100%.
Compared with comparative example 2, it can be seen from example 5 of the present utility model that only the first coating layer is provided on the surface of the separator, and the first coating layer is a glue layer, i.e., the separator without a heat-resistant layer has poor safety.
Compared with comparative example 3, it can be seen that although the separator in comparative example 3 employs the heat-resistant layer disposed at intervals, thermal runaway still occurs during partial overcharge and external short circuit test, and the test passing rate still does not reach 100%.
Compared with the embodiment 6-7, the embodiment 5 of the utility model has the advantages that the heat-resistant layers are arranged at intervals, so that the high temperature resistance of the diaphragm can be effectively improved, the heat-resistant layers cannot shrink, the heat-resistant layers arranged at intervals can uniformly improve the heat resistance of the surface of the diaphragm in a high temperature state, the diaphragm is prevented from shrinking due to heat, and in addition, the diaphragm is further controlled to shrink due to the structural support of the first coating layer on the diaphragm.
As can be seen from the above examples and comparative examples, although the lithium iron phosphate cell is used in the test process, the lithium iron phosphate cell has high safety, but in the cell with a large capacity, there is still a problem that internal heat generation is severe. Therefore, the utility model adopts the second coating layer with the structure of the heat-resistant layer arranged at intervals, and the first coating layer is matched, so that the local high temperature resistance of the diaphragm is improved, the thermal shrinkage of the diaphragm is reduced, the original structure and shape of the battery core are ensured, the problem of short circuit of the positive electrode and the negative electrode caused by local high temperature is effectively solved, the occurrence of thermal runaway is further avoided, and the safety performance of the battery is improved. Furthermore, the heat-resistant layers in the second coating layer are arranged at intervals, and grooves capable of holding electrolyte are formed between two adjacent heat-resistant layers, so that the liquid holding capacity of the diaphragm is improved, and the cycle performance of the battery is further improved.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the utility model, which are described in detail and are not to be construed as limiting the scope of the utility model. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the utility model, which are all within the scope of the utility model. Accordingly, the scope of protection of the present utility model is to be determined by the appended claims.
Claims (10)
1. A separator, comprising:
a base film including a first surface and a second surface disposed opposite to each other in a thickness direction thereof;
the first heat-resistant material layer is arranged on at least one side of the first surface and the second surface, and comprises at least one strip-shaped structure, and at least one strip-shaped structure is positioned on the tab side of the pole piece;
the second heat-resistant material layer is arranged on at least one side of the first surface and the second surface, the second heat-resistant material layer covers the surface of the base film, and when the first heat-resistant material layer and the second heat-resistant material layer are positioned on the same side surface of the base film, the second heat-resistant material layer is positioned between the first heat-resistant material layer and the base film.
2. The separator according to claim 1, wherein in the first heat-resistant material layer, the strip-like structures include at least two, at least two of the strip-like structures are arranged at intervals.
3. The separator of claim 1, wherein the first surface and the second surface are each provided with a first heat-resistant material layer, and wherein the stripe-like structures are staggered or opposed in the first heat-resistant material layers of the first surface and the second surface.
4. The membrane of claim 1, wherein the strip-like structure has a width of 10mm to 30mm.
5. The separator of claim 1, wherein the base film has a thickness of 2 μm to 40 μm.
6. The separator according to claim 1, wherein the thickness of the first heat-resistant material layer is 1 μm to 300 μm.
7. The separator according to claim 1, wherein the thickness of the second heat-resistant material layer is 0 to 10 μm.
8. The separator of any one of claims 1-7, wherein the first heat resistant material layer comprises a ceramic heat resistant layer;
the second heat resistant material layer comprises a ceramic heat resistant layer or a rubberized heat resistant layer.
9. A battery comprising a positive electrode, a separator, and a negative electrode, wherein the separator employs the separator according to any one of claims 1 to 8.
10. The battery according to claim 9, wherein the positive electrode and the negative electrode are alternately stacked, and the separator is disposed between adjacent positive electrodes and negative electrodes;
the negative electrode is disposed on a side of the separator having the first heat-resistant material layer.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202321219714.2U CN219658917U (en) | 2023-05-19 | 2023-05-19 | Separator and battery |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202321219714.2U CN219658917U (en) | 2023-05-19 | 2023-05-19 | Separator and battery |
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