CN117096470A - Electrode assembly and battery containing same - Google Patents
Electrode assembly and battery containing same Download PDFInfo
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- CN117096470A CN117096470A CN202311129477.5A CN202311129477A CN117096470A CN 117096470 A CN117096470 A CN 117096470A CN 202311129477 A CN202311129477 A CN 202311129477A CN 117096470 A CN117096470 A CN 117096470A
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- layer
- electrode assembly
- protective layer
- conductive
- separator
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- 238000002955 isolation Methods 0.000 claims description 81
- NDVLTYZPCACLMA-UHFFFAOYSA-N silver oxide Chemical compound [O-2].[Ag+].[Ag+] NDVLTYZPCACLMA-UHFFFAOYSA-N 0.000 claims description 12
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- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 7
- 238000002844 melting Methods 0.000 claims description 7
- 230000008018 melting Effects 0.000 claims description 7
- 229920000620 organic polymer Polymers 0.000 claims description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 6
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 claims description 6
- 239000005751 Copper oxide Substances 0.000 claims description 6
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 6
- 239000012790 adhesive layer Substances 0.000 claims description 6
- 229910052802 copper Inorganic materials 0.000 claims description 6
- 239000010949 copper Substances 0.000 claims description 6
- 229910000431 copper oxide Inorganic materials 0.000 claims description 6
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 6
- 229910052737 gold Inorganic materials 0.000 claims description 6
- 239000010931 gold Substances 0.000 claims description 6
- 229910052709 silver Inorganic materials 0.000 claims description 6
- 239000004332 silver Substances 0.000 claims description 6
- 229910001923 silver oxide Inorganic materials 0.000 claims description 6
- 239000006258 conductive agent Substances 0.000 claims description 5
- 229910002804 graphite Inorganic materials 0.000 claims description 5
- 239000010439 graphite Substances 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 4
- 239000004709 Chlorinated polyethylene Substances 0.000 claims description 3
- 239000004593 Epoxy Substances 0.000 claims description 3
- 239000004698 Polyethylene Substances 0.000 claims description 3
- 239000003575 carbonaceous material Substances 0.000 claims description 3
- 239000004020 conductor Substances 0.000 claims description 3
- 229920001971 elastomer Polymers 0.000 claims description 3
- 229920006242 ethylene acrylic acid copolymer Polymers 0.000 claims description 3
- 239000005038 ethylene vinyl acetate Substances 0.000 claims description 3
- 229920000573 polyethylene Polymers 0.000 claims description 3
- 229920002635 polyurethane Polymers 0.000 claims description 3
- 239000004814 polyurethane Substances 0.000 claims description 3
- 229920000915 polyvinyl chloride Polymers 0.000 claims description 3
- 239000004800 polyvinyl chloride Substances 0.000 claims description 3
- 239000005060 rubber Substances 0.000 claims description 3
- 229920001296 polysiloxane Polymers 0.000 claims description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 13
- 229910001416 lithium ion Inorganic materials 0.000 description 13
- 239000012528 membrane Substances 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 239000007774 positive electrode material Substances 0.000 description 6
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 229910052744 lithium Inorganic materials 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 239000007773 negative electrode material Substances 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
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- 238000004804 winding Methods 0.000 description 4
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- 239000010405 anode material Substances 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 239000010406 cathode material Substances 0.000 description 2
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- 238000005520 cutting process Methods 0.000 description 2
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- 238000010438 heat treatment Methods 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
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- 239000000155 melt Substances 0.000 description 2
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 239000004925 Acrylic resin Substances 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 239000002174 Styrene-butadiene Substances 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- PFYQFCKUASLJLL-UHFFFAOYSA-N [Co].[Ni].[Li] Chemical compound [Co].[Ni].[Li] PFYQFCKUASLJLL-UHFFFAOYSA-N 0.000 description 1
- HFCVPDYCRZVZDF-UHFFFAOYSA-N [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O Chemical compound [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O HFCVPDYCRZVZDF-UHFFFAOYSA-N 0.000 description 1
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 1
- 239000006183 anode active material Substances 0.000 description 1
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- 230000000712 assembly Effects 0.000 description 1
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- 230000008859 change Effects 0.000 description 1
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- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
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- 238000003487 electrochemical reaction Methods 0.000 description 1
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- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- DVATZODUVBMYHN-UHFFFAOYSA-K lithium;iron(2+);manganese(2+);phosphate Chemical compound [Li+].[Mn+2].[Fe+2].[O-]P([O-])([O-])=O DVATZODUVBMYHN-UHFFFAOYSA-K 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
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- 238000001556 precipitation Methods 0.000 description 1
- 238000011076 safety test Methods 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- 229910021384 soft carbon Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000011115 styrene butadiene Substances 0.000 description 1
- 239000011366 tin-based material Substances 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 238000003466 welding Methods 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
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
-
- 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
-
- 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
- H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- 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
- H01M50/50—Current conducting connections for cells or batteries
- H01M50/572—Means for preventing undesired use or discharge
- H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
- H01M50/586—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries inside the batteries, e.g. incorrect connections of electrodes
-
- 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
- H01M50/50—Current conducting connections for cells or batteries
- H01M50/572—Means for preventing undesired use or discharge
- H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
- H01M50/59—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries characterised by the protection means
- H01M50/597—Protection against reversal of polarity
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2200/00—Safety devices for primary or secondary batteries
- H01M2200/10—Temperature sensitive devices
-
- 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
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Connection Of Batteries Or Terminals (AREA)
Abstract
The invention discloses an electrode assembly and a battery comprising the same. The electrode assembly comprises a protective layer, the protective layer comprises a first protective layer and a second protective layer, the first protective layer is at least partially arranged on the first tab, and the second protective layer is at least partially arranged on the surface of the second active material layer; along the thickness direction of the electrode assembly, the projection of the first protective layer at least partially coincides with the projection of the second protective layer; an electrical insulation between the first protective layer and the second protective layer when the temperature of the electrode assembly is less than a threshold value; the first protective layer and the second protective layer are electrically conducted when the temperature of the electrode assembly is greater than or equal to a threshold value; the threshold is the temperature at which the first protective layer and the second protective layer are electrically conductive. When the temperature of the electrode assembly is greater than or equal to the threshold value, the first protective layer and the second protective layer are electrically conducted, so that a short circuit is formed between the first pole piece and the second pole piece, the potential difference between the anode and the cathode of the electrode assembly is reduced, the occurrence of the problem of thermal runaway of the electrode assembly is avoided, and the safety of the battery is improved.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a lithium ion battery electrode assembly and a lithium ion battery containing the same.
Background
The lithium ion battery is widely applied to the fields of electric automobiles, smart phones, notebook computers and the like due to the characteristics of small volume, high energy density, long service life and the like. However, due to its own chemical characteristics, thermal runaway is liable to occur, which causes safety accidents, and the safety of lithium ion batteries is one of the most attention-paid problems at present.
The safety risk of lithium ion batteries is mainly due to thermal runaway, which is mainly caused by the fact that the heat generation rate is far higher than the heat dissipation rate, and a large amount of heat is accumulated and cannot be dissipated. For example, lithium ion batteries generate a large amount of heat when overcharged, overdischarged or mechanically damaged, and once not handled in time, the interior of the battery rapidly rises in temperature while generating a large amount of gas, thereby causing explosion or fire. The main reason for causing thermal runaway of the battery is that heat generated by the battery during charging and discharging causes the separator to shrink under heating, thereby causing direct contact between positive and negative electrode materials in the battery. Because of potential difference of the anode material and the cathode material, severe electrochemical reaction occurs when the anode material and the cathode material are in direct contact, so that the battery rapidly generates heat and heats up.
In recent years, as the energy density and the fast charge performance of lithium ion batteries are improved, the safety problem of the lithium ion batteries is more serious.
Disclosure of Invention
The invention aims to provide an electrode assembly of a lithium ion battery and the lithium ion battery comprising the same, which can enable a first pole piece and a second pole piece to form a short circuit through electric conduction between a first protective layer and a second protective layer, thereby reducing the potential difference between the anode and the cathode of the electrode assembly, avoiding the occurrence of the problem of thermal runaway of the electrode assembly and improving the safety of the battery.
In order to achieve the above object, according to one aspect of the present invention, there is provided an electrode assembly comprising: the first pole piece comprises a first current collector, a first active material layer and a first pole lug, wherein the first active material layer and the first pole lug are arranged on at least one side surface of the first current collector, a first groove is formed in the first active material layer, and the first pole lug is arranged in the first groove and is electrically connected with the first current collector; the second pole piece comprises a second current collector and a second active material layer arranged on at least one side surface of the second current collector; the diaphragm is arranged between the first pole piece and the second pole piece; the protective layer comprises a first protective layer and a second protective layer, wherein the first protective layer is at least partially arranged on the first tab, and the second protective layer is at least partially arranged on the surface of the second active material layer; along the thickness direction of the electrode assembly, the projection of the first protective layer at least partially coincides with the projection of the second protective layer; when the temperature of the electrode assembly is less than a threshold value, electrical insulation is provided between the first protective layer and the second protective layer; when the temperature of the electrode assembly is greater than or equal to a threshold value, the first protective layer and the second protective layer are electrically conducted; the threshold is the temperature at which the first protective layer and the second protective layer are electrically conductive.
Further, the threshold value is 80-110 ℃.
Further, the protective layer includes a conductive layer and an isolation layer disposed on a surface of the conductive layer facing the separator, and when the temperature of the electrode assembly is greater than or equal to a threshold value, the isolation layer melts to expose the conductive layer or the isolation layer to have electrical conductivity.
Further, the conductive layer comprises a substrate layer and a conductive bonding layer, and the conductive bonding layer is arranged on the surface of one side, away from the diaphragm, of the substrate layer.
Further, the substrate layer comprises a conductive material comprising at least one of copper, aluminum, silver, gold, silver oxide, copper oxide, and a carbonaceous material.
Further, the conductive adhesive layer includes an adhesive and a conductive agent, the adhesive includes at least one of silicone-based, epoxy-based, polyurethane-based, polyacrylic-based, and rubber-based adhesives, and the conductive agent includes at least one of copper, aluminum, silver, graphite, gold, silver oxide, and copper oxide.
Further, the barrier layer includes an organic polymer having a melting point of 80 ℃ or more and 110 ℃ or less.
Further, the organic polymer includes at least one of polyvinyl chloride, polyethylene, chlorinated polyethylene, ethylene-vinyl acetate copolymer, and ethylene acrylic acid copolymer.
Further, the conductive layer comprises a first conductive layer, the isolation comprises a first isolation layer, the first protection layer comprises a first conductive layer and a first isolation layer, the first conductive layer is at least partially arranged on the first tab, the first conductive layer comprises a first extension part extending out of the edge of the diaphragm along the extending direction of the first tab, and the first isolation layer at least partially covers the surface of the first extension part facing one side of the diaphragm.
Further, the conductive layer further comprises a second conductive layer, the isolation layer further comprises a second isolation layer, the second protection layer comprises a second conductive layer and a second isolation layer, the second conductive layer is at least partially arranged on the surface of the second active material layer, the second conductive layer comprises a second extension part extending out of the edge of the diaphragm along the extending direction of the first tab, and the second isolation layer at least partially covers the surface of the second extension part facing one side of the diaphragm.
Further, along the extending direction of the first tab, the length of the first extension part is D1, D1 is more than or equal to 1mm and less than or equal to 20mm; and/or, along the extending direction of the first tab, the length of the second extension part is D2, and D2 is more than or equal to 1mm and less than or equal to 20mm.
Further, along the extending direction of the first tab, the length of the first isolation layer is not less than the length of the first conductive layer; and/or, along the extending direction of the first tab, the length of the second isolation layer is not smaller than the length of the second conductive layer.
Further, the first protective layer further comprises a third isolation layer, the third isolation layer is arranged between the first conductive layer and the diaphragm, and substances of the third isolation layer and the first isolation layer are the same or different; and/or the second protective layer further comprises a fourth isolation layer, the fourth isolation layer is arranged between the second conductive layer and the diaphragm, and substances of the fourth isolation layer and the second isolation layer are the same or different.
Further, the first conductive layer further comprises a first conductive main body part, and the difference between the sum of the thickness of the first isolation layer and the thickness of the first extension part and the thickness of the first conductive main body part is d1, d1 is more than or equal to 0 and less than or equal to 30 mu m; and/or the second conductive layer further comprises a second conductive main body part, wherein the difference between the sum of the thickness of the second isolation layer and the thickness of the second extension part and the thickness of the second conductive main body part is d2, and d2 is more than or equal to 0 and less than or equal to 30 mu m.
According to another aspect of the present invention, there is also provided a battery including any one of the above-described electrode assemblies.
The invention has the beneficial effects that:
the electrode assembly comprises a protective layer, wherein the protective layer comprises a first protective layer and a second protective layer, the first protective layer is at least partially arranged on a first tab, and the second protective layer is at least partially arranged on the surface of a second active material layer; along the thickness direction of the electrode assembly, the projection of the first protective layer at least partially coincides with the projection of the second protective layer; when the temperature of the electrode assembly is less than a threshold value, electrical insulation is provided between the first protective layer and the second protective layer; when the temperature of the electrode assembly is greater than or equal to a threshold value, the first protective layer and the second protective layer are electrically conducted; the threshold is the temperature at which the first protective layer and the second protective layer are electrically conductive. When the temperature of the electrode assembly is greater than or equal to the threshold value, the first protective layer and the second protective layer are electrically conducted, so that a short circuit is formed between the first pole piece and the second pole piece, the potential difference between the anode and the cathode of the electrode assembly is reduced, the occurrence of the problem of thermal runaway of the electrode assembly is avoided, and the safety of the battery is improved.
Drawings
Fig. 1 is a schematic cross-sectional structure of an electrode assembly according to the present invention;
FIG. 2 is an enlarged view showing the structure of the portion inside the broken line in FIG. 1;
FIG. 3 is a schematic view showing the structure of a first protective layer in the present invention;
FIG. 4 shows a top view of a first pole piece and a second pole piece of the present invention;
FIG. 5 is a schematic view showing a cross section of an electrode assembly parallel to the length direction of a first tab according to the present invention;
FIG. 6 shows a second schematic structural view of a cross section of the electrode assembly parallel to the length direction of the second tab according to the present invention;
FIG. 7 shows a schematic structural view of a cross section of an electrode assembly parallel to the length direction of a first tab according to the present invention;
FIG. 8 is a schematic view showing a cross-sectional structure of an electrode assembly parallel to the length direction of a first tab according to the present invention;
fig. 9 shows a schematic structural view of a winding core formed by winding according to the present invention.
Reference numerals: 1-a second current collector; 2-a second active material layer; 3-a first current collector; 4-a first active material layer; a 5-separator; 6-a second lug; 7-a first tab; 8-a protective layer; 81-a first protective layer; 811-a first conductive layer; 811 a-a first conductive body portion; 812-a first isolation layer; 82-a second protective layer; 821-a second conductive layer; 821 a-a second conductive body portion; 822-a second isolation layer; 91-a first extension; 92-second extension.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings and examples. It should be emphasized that the specific embodiments described herein are merely illustrative of some, but not all embodiments of the invention, and are not intended to limit the invention. Further, technical features relating to the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
As shown in fig. 1 to 9, the present invention provides an electrode assembly including: the first pole piece comprises a first current collector 3, a first active material layer 4 and a first pole lug 7, wherein the first active material layer 4 and the first pole lug 7 are arranged on the surface of at least one side of the first current collector 3, a first groove is formed in the first active material layer 4, and the first pole lug 7 is arranged in the first groove and is electrically connected with the first current collector 3; the second pole piece comprises a second current collector 1 and a second active material layer 2 arranged on at least one side surface of the second current collector 1; a diaphragm 5 arranged between the first pole piece and the second pole piece; the protection layer 8 comprises a first protection layer 81 and a second protection layer 82, wherein the first protection layer 81 is at least partially arranged on the first tab 7, and the second protection layer 82 is at least partially arranged on the surface of the second active material layer 2; along the thickness direction of the electrode assembly, the projection of the first protective layer 81 at least partially coincides with the projection of the second protective layer 82; when the temperature of the electrode assembly is less than the threshold value, the first protective layer 81 and the second protective layer 82 are electrically insulated from each other; when the temperature of the electrode assembly is greater than or equal to the threshold value, electrical conduction is established between the first protective layer 81 and the second protective layer 82; the threshold value is a temperature at which the first protective layer 81 and the second protective layer 82 are electrically conducted.
As shown in fig. 1, a coordinate system in space is provided, including an X-axis, a Y-axis, and a Z-axis, wherein a thickness direction of the electrode assembly extends along the X-axis; the extending direction of the first tab 7 extends along the Y-axis direction; the Z axis is spatially perpendicular to the X and Y axes.
When the temperature of the electrode assembly is greater than or equal to the threshold value, the first protective layer 81 and the second protective layer 82 are electrically conducted, so that a short circuit is formed between the first pole piece and the second pole piece, the potential difference between the anode and the cathode of the electrode assembly is reduced, the occurrence of the problem of thermal runaway of the electrode assembly is avoided, and the safety of the battery is improved.
Specifically, the threshold value may be set to 80 to 110 ℃. I.e., when the temperature of the electrode assembly is greater than or equal to a certain set threshold value within this range, electrical conduction is achieved between the first protective layer 81 and the second protective layer 82.
Wherein, protective layer 8 includes conducting layer and isolation layer, and the isolation layer sets up in the conducting layer and faces the surface of diaphragm 5 one side, and when the temperature of electrode assembly is greater than or equal to the threshold value, isolation layer melts exposing conducting layer or isolation layer and has electric conductivity. The conductive layer may be a conductive adhesive tape with adhesiveness, and the conductive layer may include a substrate layer and a conductive adhesive layer, where the conductive adhesive layer is disposed on a surface of a side of the substrate layer facing away from the diaphragm 5. The substrate layer may be a conductive material including at least one of copper, aluminum, silver, gold, silver oxide, copper oxide, and a carbonaceous material. The material of the conductive layer is selected to ensure electron conduction. The material of the conductive adhesive layer includes an adhesive and a conductive agent. Wherein the adhesive is an organic adhesive, such as at least one of organosilicon, epoxy, polyurethane, polyacrylic and rubber adhesives. Preferably, the adhesive is at least one of a polyacrylic resin and styrene-butadiene rubber. The conductive agent is selected from at least one of copper, aluminum, silver, graphite, gold, silver oxide, and copper oxide.
Preferably, the barrier layer comprises an organic polymer having a melting point greater than or equal to 80 ℃ and less than or equal to 110 ℃. For example, at least one of organic polymers such as polyvinyl chloride, polyethylene, chlorinated polyethylene, ethylene-vinyl acetate copolymer, ethylene acrylic acid copolymer, and the like. The isolation layer material can ensure that the isolation layer is melted in a melting point range of more than or equal to 80 ℃ and less than or equal to 110 ℃, so that the first protection layer 81 and the second protection layer 82 are electrically conducted, and a short circuit is formed between the positive electrode plate and the negative electrode plate.
According to a first embodiment of the present invention, as shown in fig. 1 and 2, the present invention provides an electrode assembly including a first electrode sheet, a second electrode sheet, and a separator 5 between the first electrode sheet and the second electrode sheet. The first pole piece comprises a first current collector 3, first active material layers 4 uniformly coated on two sides of the first current collector 3 and first pole lugs 7; the second tab includes a second current collector 1, a second active material layer 2 coated on both sides of the second current collector 1, and a second tab 6.
In this embodiment, tab grooves, that is, a first groove and a second groove, which are correspondingly arranged, are respectively disposed on the bodies of the first pole piece and the second pole piece. The first grooves penetrate the first active material layer 4 in the thickness direction of the first active material layer 4 and reach the surface of the first current collector 3, and the second grooves penetrate the second active material layer 2 in the thickness direction of the second active material layer 2 and reach the surface of the second current collector 3. The bottom wall of the first groove and the bottom wall of the second groove comprise a lug placement area and a blank area adjacent to the lug area, and the first lug 7 and the second lug 6 are respectively arranged in the lug placement areas of the bottom walls of the first groove and the second groove. In this embodiment, the aforementioned first groove and second groove may be provided on either side in the width direction of the positive and negative electrode current collectors.
In this embodiment, as shown in fig. 1 and fig. 2, the first groove and the second groove are respectively disposed on two sides of the diaphragm 5, and the protective layer 8 is disposed on at least a portion of the first tab 7 and at least a portion of the second active material layer 2, where the portion of the protective layer 8 extending out of the pole piece is a portion extending out of the edge of the diaphragm 5 on the tab side. The protective layer 8 can avoid the edge burrs of the tabs from piercing the diaphragm to cause direct contact between the first pole piece and the second pole piece, thereby causing thermal runaway, and can also meet ion insulation, and avoid lithium ion intercalation and migration, thereby causing lithium precipitation. When the protective layer 8 covers the first tab 7, the protective layer 8 is also adopted in the area of the second tab 6 corresponding to the position area of the first tab 7; similarly, when the protective layer 8 covers the second tab 6, the protective layer 8 is also used in the region of the first tab 7 corresponding to the location region of the second tab 6. In this embodiment, the protection layer 8 at least partially covering the first tab 7 is a first protection layer 81, and the protection layer 8 at least partially disposed on the surface of the second active material layer 2 is a second protection layer 82.
When the first pole piece, the second pole piece and the diaphragm 5 are wound to form a winding core structure, the extending part of the first protective layer 81 covered on the first pole lug 7 is in direct contact with the extending part of the second protective layer 82 in the corresponding second active material layer 2 area, so that when the temperature of the electrode assembly is greater than or equal to a threshold value, the first protective layer 81 and the second protective layer 82 realize electric conduction, thereby forming a short circuit between the positive pole piece and the negative pole piece, reducing the potential difference between the positive pole piece and the negative pole piece of the electrode assembly, avoiding the occurrence of thermal runaway problem of the electrode assembly, and improving the safety of the battery.
As shown in fig. 3, taking the first protective layer 81 as an example, the first protective layer 81 includes a first conductive layer 811 and a first isolation layer 812; the first conductive layer 811 covers the first tab 7, and is adhered to the surface of the first tab 7 facing away from the first current collector 3 and extends to the first active material layer 4; the first isolation layer 812 is provided on the surface of the first conductive layer 811 and is in direct contact with the diaphragm 5.
According to the second embodiment of the present invention, the protective layer 8 is provided on the first tab 7 and the region of the second active material layer 2 opposite to the first groove, and on the second tab 6 and the region of the first active material layer 4 opposite to the second groove. When the first pole piece, the second pole piece and the diaphragm 5 are wound to form a winding core structure, the extending part of the protective layer 8 covered on the first pole lug 7 is in direct contact with the extending part of the protective layer 8 in the corresponding second pole piece area, and the extending part of the protective layer 8 covered on the second pole lug 6 is in direct contact with the extending part of the protective layer in the corresponding first pole piece area.
Referring to fig. 5, fig. 5 is a schematic cross-sectional view of an electrode assembly parallel to the length direction of a positive tab according to an embodiment of the present invention, it can be seen that the extension length of the protective layer 8 covered on the first tab 7 to the outside of the electrode sheet exceeds the edge of the separator on the tab side, and the extension length of the protective layer 8 of the second tab region corresponding to the position region of the first tab 7 to the outside of the electrode sheet exceeds the edge of the separator on the tab side, and the distance between the extension edge of the protective layer 8 and the edge of the separator is D. Preferably, the distance D from the protruding edge of the protective layer 8 to the edge of the membrane 5 is 1 mm.ltoreq.D.ltoreq.20 mm.
According to a third embodiment of the present invention, as shown in fig. 2, the conductive layer includes a first conductive layer 811, the isolation layer includes a first isolation layer 812, the first protection layer 81 includes a first conductive layer 811 and a first isolation layer 812, and the first conductive layer 811 is at least partially disposed on the first tab 7. As shown in fig. 6, along the protruding direction of the first tab 7, i.e., the Y-axis direction in fig. 1, the first conductive layer 811 includes a first extension 91 protruding from the edge of the diaphragm 5, and the first isolation layer 812 at least partially covers the surface of the first extension 91 facing the side of the diaphragm 5.
Further, as shown in fig. 1 and fig. 6, the conductive layer further includes a second conductive layer 821, the isolation layer further includes a second isolation layer 822, the second protection layer 82 includes the second conductive layer 821 and the second isolation layer 822, the second conductive layer 821 is at least partially disposed on the surface of the second active material layer 2, along the extending direction of the first tab 7, i.e., the Y-axis direction in fig. 1, the second conductive layer 821 includes a second extension 92 extending beyond the edge of the diaphragm 5, and the second isolation layer 822 at least partially covers the surface of the second extension 92 facing the side of the diaphragm 5.
Specifically, with reference to fig. 5 and 6, along the extending direction of the first tab 7, the length of the first extension portion is D1, where 1mm is equal to or less than D1 and equal to or less than 20mm; and/or, along the extending direction of the first tab 7, the length of the second extension part is D2, and D2 is more than or equal to 1mm and less than or equal to 20mm. That is, when the upper protective layer 8 covers the second tab 6, the first pole piece region corresponding to the position region of the second tab 6 is also set by the upper protective layer 8, and the distance from the extending edge of the first pole piece region to the edge of the diaphragm is D1, wherein D1 is more than or equal to 1mm and less than or equal to 20mm. When the above protection layer 8 covers the first tab 7 in fig. 6, the above protection layer is also used for the second tab region corresponding to the position region of the first tab 7, and the distance between the extending edge of the protection layer 8 of the second tab region and the edge of the diaphragm 5 is D2, where 1mm is equal to or less than D2 is equal to or less than 20mm.
In the embodiment of the present invention, referring to fig. 6, along the extending direction of the first tab 7, the length of the first isolation layer 812 is not less than the length of the first conductive layer 811; and/or, along the extending direction of the first tab 7, the length of the second isolation layer 822 is not less than the length of the second conductive layer 821. Fig. 6 is a schematic cross-sectional view of an electrode assembly parallel to the length direction (i.e., the Y-axis direction) of a second tab according to an embodiment of the present invention, it can be seen that the extension length of the protective layer 8 covering the second tab 6 to the outside of the second tab exceeds the edge of the separator on the tab side, and the extension length of the protective layer 8 of the first tab region corresponding to the second tab position region to the outside of the first tab exceeds the edge of the separator on the tab side, and the distance between the extension edge of the protective layer 8 and the edge of the separator 5 is D, which is also aimed at enabling the extension portion of the protective layer 8 covering the first tab to be in direct contact with the extension portion of the protective layer 8 of the corresponding second tab region when the first tab, the second tab and the separator 5 are wound to form the electrode assembly; the distance D of the edge of the protective layer 8 from the edge of the membrane 5 is greater than or equal to 1mm and less than or equal to 20mm.
In the fourth embodiment of the present invention, referring to fig. 7, the first protection layer 81 further includes a third isolation layer 813, the third isolation layer 813 is disposed between the first conductive layer 811 and the diaphragm 5, and the third isolation layer 813 and the first isolation layer 812 may be the same or different; and/or the second protective layer 82 further comprises a fourth isolation layer 823, the fourth isolation layer 823 is arranged between the second conductive layer 821 and the diaphragm 5, and the fourth isolation layer 823The fourth spacer 823 may be the same as or different from the second spacer 822. Fig. 7 is a schematic cross-sectional view of an electrode assembly parallel to the longitudinal direction of the first tab 7 according to an embodiment of the present invention, it can be seen that the extension length of the protective layer 8 covering the first tab side to the outside of the first electrode sheet exceeds the edge of the separator 5 on the tab side, and the extension length of the protective layer of the second tab region corresponding to the position region of the first tab 7 to the outside of the second tab side exceeds the edge of the separator 5 on the tab side. In this embodiment, the conductive layer is provided according to the present invention, but the isolation layer is provided in two parts, the isolation layer corresponding to the active material layer of the pole piece and the position of the tab groove is an insulation layer of the prior art, namely, the third isolation layer 813 and the fourth isolation layer 823 in FIG. 7 。 The protruding portions, i.e., the first separator 812 and the second separator 822, are made of the above-mentioned separator according to the present invention, for example, an insulating material such as polypropylene, pet polyester or polyimide, and have melting points ranging from 80 to 110 c, and the separator is melted when the actual temperature of the electrode assembly exceeds the use temperature range of the electrode assembly. The distance between the protruding edge of the protective layer 8 and the edge of the membrane is D, and the purpose of this arrangement is that the protruding portion of the protective layer 8, which is covered on the first tab 7, can be in direct contact with the protruding portion of the protective layer in the corresponding second tab region when the first pole piece, the second pole piece and the membrane are wound to form an electrode assembly. Preferably, the distance D of the protruding edge of the protective layer 8 from the edge of the membrane 5 is 1 mm.ltoreq.D.ltoreq.20 mm. The arrangement reduces the manufacturing cost of the isolation layer and expands the application range of the isolation layer material on the premise of not affecting the performance of the battery assembly.
In the fifth embodiment of the present invention, referring to fig. 8, the first conductive layer 811 further includes a first conductive body portion 811a, and a difference between a sum of a thickness of the first isolation layer 812 and a thickness of the first extension portion 91 and a thickness of the first conductive body portion 811a is d1, 0.ltoreq.d1.ltoreq.30μm; and/or, the second conductive layer 821 further includes a second conductive body portion 821a, and a difference between a sum of a thickness of the second isolation layer 822 and a thickness of the second extension portion 92 and a thickness of the second conductive body portion 821a is d2, 0.ltoreq.d2.ltoreq.30μm. Fig. 8 is a schematic cross-sectional structure of an electrode assembly parallel to the length direction of the first tab, and it can be seen that the protective layer 8 is only provided with a conductive layer at the position corresponding to the active material layer and the tab groove of the pole piece, and no isolation layer is provided, but the extending portion adopts the protective layer of the present invention, that is, the conductive layer and the isolation layer are provided, the extending portion of the protective layer 8 is provided with the conductive layer on the side far away from the diaphragm, the isolation layer is provided on the side facing the diaphragm, and the isolation layer is provided on the surface of the conductive layer and can be in direct contact with the diaphragm 5. The thickness of the protective layer 8 of the protruding portion may be identical to the thickness of the conductive layer (non-protruding portion) of the protective layer 8 corresponding to the active material layer and tab groove position of the pole piece, or may be greater than the thickness of the conductive layer (non-protruding portion) of the protective layer 8 corresponding to the active material layer and tab groove position of the pole piece, i.e., the thickness of the isolation layer of the protruding portion may be set to be stepped. This structure is advantageous for better contact of the positive electrode and the negative electrode protection layer corresponding to the protruding portion. The thickness of the protective layer 8 of the extending part is larger than or equal to 0 micrometers and smaller than or equal to 30 micrometers corresponding to the difference between the thickness of the active material layer of the corresponding pole piece and the thickness of the conductive layer (non-extending part) of the protective layer 8 at the position of the lug groove; the distance D of the protruding edge of the protective layer 8 from the edge of the membrane 5 is greater than or equal to 1mm and less than or equal to 20mm. The conductive layer in this embodiment is integrally formed and has a step shape, the isolation layer is embedded in the step and thicker than the thickness of the conductive layer, and the thickness difference may be d, where d1 is 0-30 μm. The structure reduces the technical requirements of the arrangement of the conductive layer, increases the structural strength of the conductive layer, and further reduces the material consumption of the isolation layer and the cost.
When the first pole piece, the second pole piece and the diaphragm 5 are wound to form an electrode assembly, the extending part of the protective layer 8 covered on the first pole lug 7 is in direct contact with the extending part of the protective layer 8 of the corresponding second pole piece region, and the extending part of the protective layer 8 covered on the second pole lug 6 is in direct contact with the extending part of the protective layer 8 of the corresponding first pole piece region, namely the extending parts of the protective layers 8 on the first pole lug and the second pole lug which are oppositely arranged are in direct contact. In the use temperature range of the electrode assembly, the first pole piece and the second pole piece are mutually insulated, and when the actual temperature of the electrode assembly exceeds the use temperature range of the electrode assembly, the isolating layer on the extending part protecting layer is melted, so that the first pole piece 7 and the second pole piece 6 are conducted through the conducting layer on the protecting layer 8 to form a short circuit, the potential difference between the anode and the cathode of the electrode assembly is reduced, the occurrence of the problem of thermal runaway of the electrode assembly is avoided, and the safety of the battery is improved.
Preferably, the extension of the protective layer to the outside of the pole piece is an organic polymer with a melting point of 80 ℃ or more and 110 ℃ or less.
The structure of the invention is not only suitable for the pole piece with the middle-arranged structure of the pole lug, but also suitable for all pole pieces with the pole lug structure and pole pieces with the structure with the protection layer 8 arranged oppositely.
According to another aspect of the present invention, there is also provided a lithium ion battery including the above electrode assembly.
As can be seen from the description of the above embodiments, the first electrode sheet may be a positive electrode sheet or a negative electrode sheet; similarly, the second pole piece can be a negative pole piece or a positive pole piece.
In order to facilitate understanding, in the following specific embodiments, the first electrode piece is a positive electrode piece, the second electrode piece is a negative electrode piece, and other components correspond to the positive electrode piece and the negative electrode piece, so as to further explain the technical scheme of the invention. Wherein the first active material layer comprises a first active material, the first active material may comprise at least one of lithium cobaltate, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium iron phosphate, lithium-rich manganese-based material, lithium manganate or lithium manganese iron phosphate, the second active material layer comprises a second active material, and the second active material may comprise at least one of natural graphite, artificial graphite, soft carbon, hard carbon, mesophase carbon microsphere, tin-based material, silicon-based material, lithium titanate, transition metal nitride or natural crystalline flake graphite.
Example 1
The electrode assembly is prepared by the following specific processes:
the first step: preparing a positive plate, namely taking lithium cobaltate as a positive electrode active material, adding the positive electrode active material, conductive carbon black and polyvinylidene fluoride as a binder into a stirring tank according to the mass ratio of 98.6:0.4:1.0, adding NMP to prepare slurry for forming a positive electrode active material layer, coating the positive electrode slurry on a current collector by using a coating machine, drying the positive electrode plate to obtain the positive electrode plate, and cutting to obtain the positive electrode plate with the positive electrode width of specific requirements.
And a second step of: preparing a negative plate, namely taking graphite as a negative active material, adding the negative active material, conductive carbon black, a dispersing agent sodium carboxymethyl cellulose and a binder styrene-butadiene latex into a stirring tank according to the mass ratio of 96.9:0.5:1.3:1.3, adding deionized water, and fully stirring to prepare a negative slurry, wherein the solid content of the negative slurry is 45-50 wt%. And coating the slurry gap of the anode active material on the surface of an anode current collector by using a coating machine, drying the electrode plate to obtain an anode plate, and cutting to obtain the electrode plate with the anode width of specific requirements.
And a third step of: and cleaning the cut positive and negative electrode plates on cleaning equipment to obtain corresponding lug grooves, welding positive and negative electrode lugs on the corresponding lug grooves, and bonding protective layers on the positive and negative electrode lug positions and positive and negative electrode active material layers corresponding to the positive and negative electrode lugs.
Fourth step: the electrode assembly was assembled, and the negative electrode sheet prepared as described above was wound together with the positive electrode sheet and the separator to form a roll core, as shown in fig. 9. And packaging the roll core by using an aluminum plastic film, baking to remove water, injecting electrolyte, and performing thermocompression forming process to obtain the electrode assembly.
Examples 2 to 5
The procedure was as described above, except that each protective layer extended edge was spaced from the edge of the membrane, as shown in Table 1.
Example 6
Referring to the operation steps of embodiment 1, except that the conductive layer is the same as embodiment 1, but the separator is divided into two parts, the separator corresponding to the positions of the active material layer of the electrode tab and the grooves of the electrode tab is made of a polypropylene insulating material, the melting point is above 110 ℃, the separator of the part is not melted when the actual temperature of the electrode assembly exceeds the use temperature range of the electrode assembly, the separator of the present invention is used as the protruding part, and the distance D between the protruding edge of the protective layer 8 and the edge of the separator is 5mm, as shown in fig. 7.
Example 7
Referring to the operation procedure of example 1, except that the protective layer was provided with only the conductive layer and no isolation layer at the protective layer 8 corresponding to the positions of the active material layer of the pole piece and the recess of the tab, but the protective layer 8 of the present invention was provided at the extension portion, that is, the conductive layer and the isolation layer were provided, the difference between the thickness of the protective layer at the extension portion and the thickness of the conductive layer (non-extension portion) corresponding to the positions of the active material layer of the pole piece and the recess of the tab was 10 μm, and the distance D between the extension edge of the protective layer 8 and the edge of the separator was 5mm, as shown in fig. 8.
Comparative example 1
Referring to the operation procedure of embodiment 1, the protective layer is still electrically insulated after the temperature change, and no electrically conductive structure is formed, so that positive and negative electrode conduction cannot be achieved. The protective layer in this comparative example 1 was made of a common insulating adhesive tape, i.e., an insulating tape of the prior art.
Safety tests were carried out on the batteries of specific examples 1 to 5 and comparative examples 1 to 2, and the test steps were as follows: the electrode assembly was charged to a full-power state (4.5V), and then the electrode assembly was placed in an oven, which was set to heat up to 150 ℃ at a heating rate of 2 ℃/min, and held for 60min. And the electrode assembly voltage, surface temperature and final state during the test were recorded, and specific results are shown in table 1.
TABLE 1
As can be seen from table 1, when the surface temperature of the electrode assembly exceeds 100 ℃, the voltage will rapidly approach 0V, and the distance D between the edge of the protective layer and the edge of the separator in embodiments 1 to 5 increases, i.e. the area of the protective layer protruding portion covered on the tab directly contacting the corresponding positive and negative electrode region protective layer protruding portion increases, the electrode assembly will be shorted at a lower temperature, and no thermal runaway phenomenon occurs in the electrode assembly.
Example 6 shows that thermal runaway does not occur, and that only the protruding portion uses the barrier layer of the present invention to effectively enhance the safety performance. Embodiment 7 does not exhibit thermal runaway, and the electrode assembly will be shorted at a lower temperature, further improving safety.
The electrode assembly corresponding to the comparative example 1 also has no thermal runaway phenomenon, but the surface temperature of the electrode assembly is higher, and the failure risk is higher; comparative example 2 corresponds to a sudden voltage drop of 0V at 135 c, followed by failure to fire.
Therefore, the protective layer extending part covered on the positive electrode lug or the positive electrode active material layer is directly contacted with the corresponding protective layer extending part of the negative electrode area, the protective layer extending part covered on the negative electrode lug or the negative electrode active material layer is directly contacted with the corresponding protective layer extending part of the positive electrode area, so that the positive electrode plate and the negative electrode plate are mutually insulated in the use temperature range of the electrode assembly, but when the actual temperature of the electrode assembly exceeds the use temperature range of the electrode assembly, the isolation layer on the protective layer is melted, the positive electrode plate and the negative electrode plate are conducted through the conductive layer on the protective layer to form a short circuit, the potential difference of the positive electrode and the negative electrode is reduced, the occurrence of the thermal runaway problem of the electrode assembly is avoided, and the safety of the electrode assembly is improved.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications could be made by those skilled in the art without departing from the technical principles of the present invention, and such modifications should also be considered as being within the scope of the present invention.
Claims (15)
1. An electrode assembly, comprising:
the first pole piece comprises a first current collector (3), a first active material layer (4) and a first pole lug (7), wherein the first active material layer (4) and the first pole lug (7) are arranged on the surface of at least one side of the first current collector (3), a first groove is formed in the first active material layer (4), and the first pole lug (7) is arranged in the first groove and is electrically connected with the first current collector (3);
the second pole piece comprises a second current collector (1) and a second active material layer (2) arranged on at least one side surface of the second current collector (1);
a diaphragm (5) provided between the first pole piece and the second pole piece;
the protection layer (8) comprises a first protection layer (81) and a second protection layer (82), wherein the first protection layer (81) is at least partially arranged on the first tab (7), and the second protection layer (82) is at least partially arranged on the surface of the second active material layer (2);
along the thickness direction of the electrode assembly, the projection of the first protective layer (81) and the projection of the second protective layer (82) are at least partially overlapped;
-when the temperature of the electrode assembly is less than a threshold value, an electrical insulation between the first protective layer (81) and the second protective layer (82);
-when the temperature of the electrode assembly is greater than or equal to a threshold value, electrical conduction between the first protective layer (81) and the second protective layer (82);
the threshold value is a temperature at which the first protective layer (81) and the second protective layer (82) are electrically conducted.
2. The electrode assembly of claim 1, wherein the threshold is 80 ℃ to 110 ℃.
3. The electrode assembly according to claim 2, wherein the protective layer (8) includes a conductive layer and an isolation layer provided on a surface of the conductive layer on a side facing the separator (5), the isolation layer being melted to expose the conductive layer or the isolation layer to have electrical conductivity when the temperature of the electrode assembly is greater than or equal to the threshold value.
4. The electrode assembly of claim 3, wherein the conductive layer comprises a substrate layer and a conductive adhesive layer disposed on a surface of the substrate layer facing away from the separator.
5. The electrode assembly of claim 4, wherein the substrate layer comprises a conductive material comprising at least one of copper, aluminum, silver, gold, silver oxide, copper oxide, and a carbonaceous material.
6. The electrode assembly of claim 5, wherein the conductive adhesive layer comprises an adhesive comprising at least one of silicone-based, epoxy-based, polyurethane-based, polyacrylic-based, rubber-based adhesives, and a conductive agent comprising at least one of copper, aluminum, silver, graphite, gold, silver oxide, and copper oxide.
7. The electrode assembly of claim 6, wherein the separator layer comprises an organic polymer having a melting point greater than or equal to 80 ℃ and less than or equal to 110 ℃.
8. The electrode assembly of claim 7, wherein the organic polymer comprises at least one of polyvinyl chloride, polyethylene, chlorinated polyethylene, ethylene vinyl acetate copolymer, and ethylene acrylic acid copolymer.
9. The electrode assembly according to any one of claims 2-8, wherein the conductive layer comprises a first conductive layer (811), the isolation layer comprises a first isolation layer (812), the first protection layer (81) comprises the first conductive layer (811) and the first isolation layer (812), the first conductive layer (811) is at least partially provided on the first tab (7), the first conductive layer (811) comprises a first extension (91) protruding from an edge of the separator (5) along a protruding direction of the first tab (7), and the first isolation layer (812) at least partially covers a surface of the first extension (91) facing a side of the separator (5).
10. The electrode assembly of claim 9, wherein the conductive layer further comprises a second conductive layer (821), the separator further comprises a second separator layer (822), the second protective layer (82) comprises the second conductive layer (821) and the second separator layer (822), the second conductive layer (821) is at least partially disposed on the surface of the second active material layer (2), along the extending direction of the first tab (7), the second conductive layer (821) comprises a second extension (92) extending out of the edge of the separator (5), and the second separator layer (822) at least partially covers the surface of the second extension (92) facing the separator (5).
11. The electrode assembly according to claim 9, wherein the length of the first extension portion is D1,1 mm-20 mm along the protruding direction of the first tab (7); and/or, along the extending direction of the first tab (7), the length of the second extension part is D2, and D2 is more than or equal to 1mm and less than or equal to 20mm.
12. The electrode assembly according to claim 10 or 11, wherein a length of the first separator layer (812) is not less than a length of the first conductive layer (811) along the protruding direction of the first tab (7); and/or the number of the groups of groups,
along the extending direction of the first tab (7), the length of the second isolation layer (822) is not smaller than the length of the second conductive layer (821).
13. The electrode assembly according to claim 10 or 11, wherein the first protective layer (81) further comprises a third separator layer (813), the third separator layer (813) is provided between the first conductive layer (81) and the separator (5), and the third separator layer (813) and the first separator layer (812) may be the same or different; and/or the number of the groups of groups,
the second protection layer (82) further comprises a fourth isolation layer (823), the fourth isolation layer (823) is arranged between the second conductive layer (821) and the diaphragm (5), and substances of the fourth isolation layer (823) and the second isolation layer (822) can be the same or different.
14. The electrode assembly according to claim 10 or 11, wherein the first conductive layer (811) further comprises a first conductive body portion (811 a), and a difference between a sum of a thickness of the first separator layer (812) and a thickness of the first extension portion (91) and a thickness of the first conductive body portion (811 a) is d1, 0.ltoreq.d1.ltoreq.30μm; and/or the number of the groups of groups,
the second conductive layer (821) further includes a second conductive body portion (821 a), and a difference between a sum of a thickness of the second isolation layer (822) and a thickness of the second extension portion (92) and a thickness of the second conductive body portion (821 a) is d2, and d2 is 0 or less and 30 μm or less.
15. A battery comprising the electrode assembly of any one of claims 1 to 14.
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| CN202311129477.5A CN117096470A (en) | 2023-09-01 | 2023-09-01 | Electrode assembly and battery containing same |
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