CN113707841A - Electrode assembly and application thereof - Google Patents
Electrode assembly and application thereof Download PDFInfo
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- CN113707841A CN113707841A CN202111001427.XA CN202111001427A CN113707841A CN 113707841 A CN113707841 A CN 113707841A CN 202111001427 A CN202111001427 A CN 202111001427A CN 113707841 A CN113707841 A CN 113707841A
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- 229920000642 polymer Polymers 0.000 claims abstract description 93
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims abstract description 56
- 229910001416 lithium ion Inorganic materials 0.000 claims abstract description 56
- 239000006258 conductive agent Substances 0.000 claims description 8
- 238000003475 lamination Methods 0.000 claims description 4
- 239000000853 adhesive Substances 0.000 claims description 2
- 230000001070 adhesive effect Effects 0.000 claims description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 16
- 229910052782 aluminium Inorganic materials 0.000 description 16
- 239000011888 foil Substances 0.000 description 10
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 6
- 239000011230 binding agent Substances 0.000 description 6
- 239000011889 copper foil Substances 0.000 description 6
- -1 polyethylene Polymers 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 238000004146 energy storage Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 239000002270 dispersing agent Substances 0.000 description 4
- 238000009863 impact test Methods 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 239000012634 fragment Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000007773 negative electrode material Substances 0.000 description 3
- 239000007774 positive electrode material Substances 0.000 description 3
- 230000002035 prolonged effect Effects 0.000 description 3
- 239000004743 Polypropylene Substances 0.000 description 2
- 238000001467 acupuncture Methods 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 239000002985 plastic film Substances 0.000 description 2
- 229920006255 plastic film Polymers 0.000 description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 description 2
- 239000005020 polyethylene terephthalate Substances 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical group [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004793 Polystyrene Substances 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
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
- 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
-
- 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
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Connection Of Batteries Or Terminals (AREA)
Abstract
The invention provides an electrode assembly and application thereof. The electrode assembly comprises an electrode assembly body and a first polymer layer, wherein the electrode assembly body comprises a positive plate and a negative plate which are separated by a diaphragm, and the first polymer layer is positioned on at least part of the periphery of the electrode assembly body. In the invention, because the first polymer layer is close to the outermost layer of the electrode assembly, when foreign matters penetrate into the electrode assembly, the situation that the positive electrode current collector is damaged to cause the contact of positive electrode current collector scraps and a negative electrode to generate short circuit can be avoided, and the safety performance of the lithium ion battery can be improved.
Description
Technical Field
The invention relates to an electrode assembly and application thereof, and belongs to the technical field of lithium ion batteries.
Background
The lithium ion battery is widely applied to the fields of consumer electronics, new energy vehicles, energy storage and the like due to the advantages of high energy density, good cycle performance, small pollution and the like, however, due to the material and process of the lithium ion battery, the lithium ion battery has a greater risk of safety failure, and when the lithium ion battery is punctured, extruded and impacted by the outside, the conditions of fire, combustion and the like which harm the human health can occur.
When a lithium ion battery is squeezed by foreign objects or is pierced by sharp instruments, four short circuit modes of the battery can occur: the anode and the cathode are in short circuit, the anode and the copper foil are in short circuit, the aluminum foil and the copper foil are in short circuit, and the aluminum foil and the cathode are in short circuit, wherein the aluminum foil and the cathode are in short circuit, the resistance is small, the heat is more, the reaction is fast, and the short circuit mode is the most dangerous one. The most outside of the conventional lithium ion battery is a hollow aluminum foil, when foreign matters penetrate into the lithium ion battery, the aluminum foil is firstly contacted, a large amount of aluminum scraps can be generated by the aluminum foil under an external acting force, and when the foreign matters continue to penetrate into the lithium ion battery, the aluminum scraps can be contacted with a negative electrode and a copper foil, so that the short circuit between the aluminum foil and the negative electrode is generated. Therefore, there is a need to develop a lithium ion battery having improved safety.
Disclosure of Invention
The invention provides an electrode assembly, when foreign matters are penetrated, a positive current collector in the electrode assembly is hardly damaged, so that the situation that the positive current collector and a negative electrode are short-circuited due to contact of fragments of the positive current collector and the negative electrode can be effectively avoided, and the safety performance of a lithium ion battery is improved.
The invention provides a lithium ion battery, when foreign matters are penetrated, the positive current collector in the lithium ion battery is hardly damaged, so that the situation of short circuit between the positive current collector and a negative electrode caused by contact between fragments of the positive current collector and the negative electrode can be effectively avoided, and the lithium ion battery has higher safety performance.
The invention provides an electrode assembly, which comprises an electrode assembly body and a first polymer layer, wherein the electrode assembly body comprises a positive plate and a negative plate which are separated by a diaphragm, and the first polymer layer is positioned on at least part of the periphery of the electrode assembly body.
The electrode assembly as set forth above, wherein the electrode assembly is a lamination stack;
the first polymer layer covers at least one side of the electrode assembly body, a first conducting layer is arranged on one surface, facing the electrode assembly body, of the first polymer layer, and a positive active layer is arranged on the functional surface, away from the first polymer layer, of the first conducting layer.
The electrode assembly as described above, wherein the electrode assembly is in a wound structure;
the first polymer layer is located at an outermost layer of the electrode assembly body.
The electrode assembly as described above, wherein the positive electrode tab includes a positive electrode current collector including a main body portion and an extension portion connected to each other, at least one functional surface of the main body portion having a positive electrode active layer;
the extension includes at least a first polymer layer, and the first polymer layer is located at an outermost layer of the electrode assembly body.
The electrode assembly as described above, wherein the extension portion further comprises a first conductive layer, the first conductive layer and the first polymer layer being disposed in a stack;
the main body portion includes a second conductive layer, and the first conductive layer and the second conductive layer are integrally connected.
The electrode assembly as described above, wherein the extension portion further includes a first conductive layer, the main body portion includes a second conductive layer, the first conductive layer and the second conductive layer are overlapped and connected, and a length of the overlapped portion is 5-20 mm.
The electrode assembly as described above, wherein a conductive agent and/or a binder is included between the first conductive layer and the first polymer layer.
The electrode assembly as described above, wherein the main body portion further includes a second polymer layer, the second conductive layer is located on at least one functional surface of the second polymer layer, and the second conductive layer is provided with the positive electrode active layer away from the functional surface of the second polymer layer.
The electrode assembly as described above, wherein the first polymer layer and the second polymer layer are integrally connected or separately connected.
The invention provides a lithium ion battery which comprises the electrode assembly.
The electrode assembly comprises an electrode assembly body and a first polymer layer, wherein the electrode assembly body comprises a positive plate and a negative plate which are separated by a diaphragm, and the first polymer layer is positioned on at least part of the periphery of the electrode assembly body. In the invention, the first polymer layer is positioned on at least part of the periphery of the electrode assembly body, so when foreign matters penetrate into the electrode assembly, the situation that the positive electrode current collector scraps are contacted with the negative electrode to generate short circuit due to damage of the positive electrode current collector can be avoided, and the safety performance of the lithium ion battery can be improved.
According to the lithium ion battery provided by the invention, due to the electrode assembly, when foreign matters penetrate into the lithium ion battery, the positive current collector is hardly damaged, and the short circuit caused by the contact of positive current collector debris and a negative electrode due to the damage of the positive current collector can be avoided.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the related art, the drawings used in the description of the embodiments of the present invention or the related art are briefly introduced below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
FIG. 1 is a schematic cross-sectional view of an electrode assembly according to some embodiments of the present invention;
FIG. 2 is a schematic diagram of the positive plate structure according to some embodiments of the present invention;
fig. 3 is a schematic structural diagram of a positive electrode sheet according to another embodiment of the present invention.
Description of reference numerals:
1: an electrode assembly body;
2: a first polymer layer;
3: a diaphragm;
4: a positive plate;
5: a negative plate;
6: a first conductive layer;
7: a second conductive layer;
8: an overlapping portion;
41: a positive current collector;
42: a positive electrode active layer;
51: a negative current collector;
52: and a negative electrode active layer.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the present invention, the functional surfaces refer to two surfaces having the largest areas and being oppositely disposed among the first polymer layer, the first conductive layer, the second conductive layer, or the current collector.
Fig. 1 is a schematic cross-sectional view of an electrode assembly according to some embodiments of the present invention. As shown in fig. 1, a first aspect of the present invention provides an electrode assembly comprising an electrode assembly body 1 and a first polymer layer 2, the electrode assembly body 1 comprising a positive electrode tab 4 and a negative electrode tab 5 separated by a separator 3, the first polymer layer 2 being located at least partially around the periphery of the electrode assembly body 1.
The electrode assembly body 1 of the present invention includes the positive electrode sheet 4 and the negative electrode sheet 5 separated by the separator 3, and it is understood that, in the present invention, the positive electrode sheet 4, the separator 3, and the negative electrode sheet 5 are stacked in the linear direction to obtain the electrode assembly body 1 of a laminated structure, and the positive electrode sheet 4, the separator 3, and the negative electrode sheet 5 are stacked in the circumferential direction to obtain the electrode assembly body 1 of a wound structure.
The positive electrode sheet 4 of the present invention includes a positive electrode current collector 41 and a positive electrode active layer 42 provided on at least one functional surface of the positive electrode current collector 41. The positive electrode current collector 41 according to the present invention is not particularly limited, and may be a positive electrode current collector 41 commonly used in the art, for example, an aluminum foil. The positive electrode active layer 42 according to the present invention is not particularly limited, and may be a positive electrode active layer 42 commonly used in the art, for example, the positive electrode active layer 42 may include a positive electrode active material, a binder, a conductive agent, and a dispersant.
The negative electrode sheet 5 of the present invention includes a negative electrode collector 51 and a negative electrode active layer 52 disposed on at least one functional surface of the negative electrode collector 51. The negative electrode collector 51 of the present invention is not particularly limited, and may be a negative electrode collector 51 commonly used in the art, and may be, for example, a copper foil. The negative electrode active layer 52 is not particularly limited in the present invention, and may be a negative electrode active layer 52 commonly used in the art, for example, the negative electrode active layer 52 may include a negative electrode active material, a binder, a conductive agent, and a dispersant.
The positive electrode active material, the negative electrode active material, the binder, the conductive agent, and the dispersant are selected from the positive electrode active material, the negative electrode active material, the binder, the conductive agent, and the dispersant, which are commonly used in the art.
The separator 3 of the present invention is not particularly limited, and a separator 3 commonly used in the art may be used.
The first polymer layer 2 is not particularly limited in the present invention and may be formed of a polymer commonly used in the art, for example, the polymer may be at least one of polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyethylene terephthalate. In the present invention, the first polymer layer 2 may be disposed on the entire outer circumference of the electrode assembly body 1, or may be disposed on at least a portion of the outer circumference of the electrode assembly body 1.
In the invention, since the first polymer layer 2 is arranged on at least part of the periphery of the electrode assembly body 1, when the electrode assembly is penetrated by foreign matters, the foreign matters can firstly contact the first polymer layer 2, so that the first polymer layer 2 can protect the positive electrode current collector 41, the positive electrode current collector 41 is hardly damaged, and the situation that the damaged debris of the positive electrode current collector 41 contacts with the negative electrode sheet 5 to generate short circuit can be effectively avoided; and since the first polymer layer 2 has a high elongation, the electrode assembly is also hardly damaged when the electrode assembly is impacted by a heavy object, thereby further effectively protecting the positive current collector 41, so that the electrode assembly can improve the safety performance of the lithium ion battery.
As shown in fig. 1, in some embodiments of the present invention, the electrode assembly is a lamination stack;
the first polymer layer 2 covers at least one side of the electrode assembly body 1, the functional surface of the first polymer layer 2 facing the electrode assembly body 1 is provided with a first conductive layer 6, and the functional surface of the first conductive layer 6 remote from the first polymer layer 2 is provided with a positive electrode active layer 42.
In the present invention, if the electrode assembly body 1 is a laminate structure, the first polymer layer 2 is disposed on at least one side of the electrode assembly body 1, so that an electrode assembly of the laminate structure can be formed.
The material of the first conductive layer 6 is not particularly limited in the present invention, and the material of the first conductive layer 6 may be selected from conductive materials commonly used in the art, and may be at least one of aluminum, nickel and stainless steel, for example. In the present invention, the first conductive layer 6 is disposed on the functional surface of the first polymer layer 2 facing the electrode assembly body 1, and the positive electrode active layer 42 is disposed on the functional surface of the first conductive layer 6 away from the first polymer layer 2, so that the conductivity of the electrode assembly can be improved on the premise of improving the mechanical properties of the electrode assembly. It is understood that the separator 3 is disposed between the positive electrode active layer 42 and the electrode assembly body 1.
The electrode assembly of the lamination structure is sequentially provided with a first polymer layer 2, a first conductive layer 6, a positive electrode active layer 42, a separator 3 and an electrode assembly body 1 from top to bottom, or sequentially provided with the first polymer layer 2, the first conductive layer 6, the positive electrode active layer 42, the separator 3, the electrode assembly body 1, the separator 3, the positive electrode active layer 42, the first conductive layer 6 and the first polymer layer 2 from top to bottom.
In some embodiments of the invention, the electrode assembly is in a wound structure;
the first polymer layer 2 is located at the outermost layer of the electrode assembly body 1.
In the present invention, if the electrode assembly body 1 is in a wound structure, the first polymer layer 2 is disposed on the outermost layer of the electrode assembly body 1, so that an electrode assembly of a wound structure can be formed.
FIG. 2 is a schematic diagram of the positive plate structure according to some embodiments of the present invention; fig. 3 is a schematic structural diagram of a positive electrode sheet according to another embodiment of the present invention. As shown in fig. 2 or 3, in some embodiments of the present invention, the positive electrode sheet 4 includes a positive electrode collector 41, the positive electrode collector 41 includes a main portion and an extension portion connected to each other, at least one functional surface of the main portion having a positive electrode active layer 42;
the extended portion includes at least the first polymer layer 2, and the first polymer layer 2 is located at the outermost layer of the electrode assembly body 1.
The positive electrode collector 41 of the present invention includes a main body portion and an extension portion connected to each other, and the present invention does not limit the connection manner of the main body portion and the extension portion. The structure of the main body portion is not particularly limited in the present invention, and may be a positive electrode current collector 41 commonly used in the art.
In the present invention, the positive electrode active layer 42 may be provided on one functional surface of the main body portion, or the positive electrode active layers 42 may be provided on both functional surfaces of the main body portion, which may be used to form the electrode assembly body 1 by being stacked with the negative electrode tab 5.
The extended portion includes at least the first polymer layer 2, and the first polymer layer 2 is located at the outermost layer of the electrode assembly body formed of the main body portion and the negative electrode tab 5.
As shown in fig. 2, in some embodiments of the present invention, the extension portion further comprises a first conductive layer 6, the first conductive layer 6 and the first polymer layer 2 being disposed in a stack;
the body portion comprises a second conductive layer 7, the first conductive layer 6 and the second conductive layer 7 being integrally connected.
The present invention is not limited to the specific material of the second conductive layer 7, and may be a conductive material commonly used in the art, for example, at least one of aluminum, nickel, and stainless steel. In the present invention, the first conductive layer 6 is laminated with the first polymer layer 2 in the circumferential direction, and the first polymer layer 2 is disposed on the outermost layer of the electrode assembly body 1.
As shown in fig. 3, in some embodiments of the present invention, the extension portion further includes a first conductive layer 6, the main body portion includes a second conductive layer 7, the first conductive layer 6 and the second conductive layer 7 are overlapped and connected, and the length of the overlapped portion 8 is 5 to 20 mm.
In the present invention, a first extending portion is reserved at one end of the first conductive layer 6 close to the second conductive layer 7, and a second extending portion is reserved at one end of the second conductive layer 7 close to the first conductive layer 6, so that the first extending portion and the second extending portion are connected in an overlapping manner. The length of the first extension and the second extension may be 10-30 mm. The connection method of the first extension portion and the second extension portion is not particularly limited, and a connection method commonly used in the art may be selected, for example, ultrasonic welding may be selected to connect the first extension portion and the second extension portion in an overlapping manner.
In the present invention, when the length of the overlapping portion 8 is too long, the weight of the lithium ion battery is increased, and the energy density of the lithium ion battery is reduced, and when the length of the overlapping portion 8 is too short, the connection strength between the first conductive layer 6 and the second conductive layer 7 is too low, and the first conductive layer 6 and the second conductive layer 7 are easily peeled off with the use of the lithium ion battery, thereby shortening the service life of the lithium ion battery. When the length of the overlapping part 8 is 5-20mm, the service life of the lithium ion battery can be prolonged on the premise of ensuring the energy density of the lithium ion battery.
In some embodiments of the present invention, a binder and/or a conductive agent is included between first conductive layer 6 and first polymer layer 2.
In the invention, the conductive agent is arranged between the first conductive layer 6 and the first polymer layer 2, so that the conductivity of the electrode assembly can be improved, and the rate charge and discharge performance of the lithium ion battery can be improved; the adhesive is arranged between the first conductive layer 6 and the first polymer layer 2, so that the first conductive layer 6 and the first polymer layer 2 can be attached more closely, the first conductive layer 6 and the first polymer layer 2 are prevented from being peeled off in the long-term use of the electrode assembly, the service life of the electrode assembly is prolonged, and the service life of the lithium ion battery is prolonged.
In some embodiments of the invention, the body portion further comprises a second polymer layer, the second conductive layer 7 being located on at least one functional surface of the second polymer layer, the second conductive layer 7 being provided with a positive active layer 42 remote from the functional surface of the second polymer layer.
In the present invention, the main body portion further includes a second polymer layer, and the second conductive layer 7 may be located on one functional surface of the second polymer layer, and the second conductive layer 7 may also be located on both functional surfaces of the second polymer layer. The invention arranges a positive active layer 42 on the functional surface of the second conductive layer 7 far away from the second polymer layer, which is used for ensuring the normal charge and discharge of the battery.
In the invention, when the main body part further comprises the second polymer layer, when foreign matters penetrate into the electrode assembly, the second polymer layer can further avoid the situation that the positive current collector 41 and the negative electrode are short-circuited due to the fact that the fragments of the positive current collector 41 are in contact with the negative electrode, and the safety performance of the lithium ion battery is improved.
In the present invention, the first polymer layer 2 and the second polymer layer may be integrally connected or separately connected.
A second aspect of the invention provides a lithium ion battery comprising the electrode assembly described above.
The above electrode assembly is placed in an outer package, and an electrolyte is injected into the outer package, whereby a lithium ion battery can be obtained.
According to the lithium ion battery provided by the invention, due to the electrode assembly, when foreign matters penetrate into the lithium ion battery, the foreign matters can firstly contact the first polymer layer 2, so that the first polymer layer 2 can protect the positive electrode current collector 41, the positive electrode current collector 41 is hardly damaged, and the short circuit caused by the contact of damaged debris of the positive electrode current collector 41 and the negative electrode sheet 5 can be effectively avoided; and since the first polymer layer 2 in the electrode assembly has a high elongation, the electrode assembly is also hardly damaged when the electrode assembly is impacted by a heavy object, thereby further effectively protecting the positive current collector 41, so that the electrode assembly can improve the safety performance of the lithium ion battery.
The invention also provides an electronic device, and the driving source and/or the energy storage source of the electronic device comprise the lithium ion battery.
The lithium ion battery can be used as a power source of electronic equipment, and can also be used as an energy storage unit of the electronic equipment. The electronic devices may include, but are not limited to, mobile devices (e.g., mobile phones, notebook computers, etc.), electric vehicles (e.g., electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, and the like.
The electronic device of the invention has high safety performance because the driving source and/or the energy storage source comprise the lithium ion battery.
The technical means of the present invention will be further described below with reference to specific examples.
Example 1
The structure of the laminated electrode assembly of the present embodiment, with reference to fig. 1, specifically includes: an electrode assembly body 1 and a first polymer layer 2;
the electrode assembly body 1 comprises 5 positive electrode sheets and 6 negative electrode sheets which are arranged in a stacked manner;
the first polymer layer 2 covers both sides of the electrode assembly body 1, the functional surface of the first polymer layer 2 facing the electrode assembly body 1 is provided with a first conductive layer 6, and the functional surface of the first conductive layer 6 away from the first polymer layer 2 is provided with a positive electrode active layer 42;
the positive plate 4 comprises an aluminum foil and positive active layers 42 arranged on two functional surfaces of the aluminum foil;
the negative electrode sheet 5 includes a copper foil and negative electrode active layers 52 provided on both functional surfaces of the copper foil;
a polypropylene diaphragm is arranged between the negative electrode sheet 5 and the positive electrode active layer 42;
the positive electrode active layer 42 has a mass composition of lithium cobaltate: polyvinylidene fluoride: carbon black 95: 2: 3, the negative electrode active layer 52 has a mass composition of graphite: styrene-butadiene rubber: carbon black: sodium carboxymethylcellulose 94: 2: 2: 2, the first conductive layer 6 is an aluminum-plated layer, and the material of the first polymer layer 2 is polyethylene terephthalate.
Example 2
The jelly-roll type electrode assembly of the present embodiment specifically includes:
as shown in fig. 3, the positive electrode sheet 4 includes a positive electrode current collector 41, the positive electrode current collector 41 includes a main portion and an extended portion connected to each other, and both functional surfaces of the main portion are provided with positive electrode active layers 42;
the extension portion comprises a first polymer layer 2 and a first conductive layer 6, wherein the first polymer layer 2 and the first conductive layer 6 are arranged in a stacked mode;
the main body part comprises a second conducting layer 7, the second conducting layer 7 is connected with the first conducting layer 6 in an overlapping mode, and the length of an overlapping part 8 is 10 mm;
stacking the positive electrode sheet 4, the separator 3, and the negative electrode sheet 5 to obtain a stack, and winding the stack with the first polymer layer 2 positioned on the outermost layer of the electrode assembly to obtain a wound-type electrode assembly of the present embodiment;
the positive electrode sheet 4, the negative electrode sheet 5, and the separator 3 are the same as in example 1.
Comparative example 1
The electrode assembly of this comparative example had substantially the same structure as example 1, except that the first polymer layer 2 of example 1 was not included.
Comparative example 2
The electrode assembly of this comparative example had substantially the same structure as example 2, except that positive electrode tab 4 in example 2 was replaced with a positive electrode tab that did not include an extension portion.
Test examples
The electrode assemblies obtained in examples 1-2 and comparative examples 1-2 were placed in an aluminum plastic film, packaged, and an electrolyte was injected into the aluminum plastic film to obtain a lithium ion battery having a capacity of 4930 mAh.
The following tests were carried out on the lithium ion batteries obtained in the experimental examples, and the test results are shown in table 1:
1) full electric needle prick test
And (3) placing the lithium ion battery in a normal temperature environment, charging the lithium ion battery to a voltage of 4.45V by using a constant current of 0.5C, then charging at a constant voltage until the current is reduced to 0.02C, and stopping charging. And (3) vertically penetrating the center, the left side and the right side of the lithium ion battery at the speed of 150mm/s by using a steel needle with the diameter of 2.5mm, keeping for 300s, and recording that the lithium ion battery passes when the lithium ion battery does not catch fire and explode. Each lithium ion battery is tested by 15, the left, middle and right positions are respectively tested by 5, the acupuncture test passing rate is calculated, and the safety of the lithium ion battery is evaluated according to the acupuncture test passing rate.
2) Weight impact test
Placing the lithium ion battery in a normal temperature environment, charging the lithium ion battery with a constant current of 0.2C until the voltage is 4.45V, then charging with a constant voltage until the current is reduced to 0.025C, stopping charging, then discharging with a constant current of 0.5C, discharging to 3.0V, circulating for 5 times, and performing a weight impact test within 24 hours after the last time of full charge of the lithium ion battery;
the battery core is placed on a plane, a steel column with the diameter of 15.8 +/-0.2 mm is placed in the center of the battery core, the longitudinal axis of the steel column is parallel to the plane, a weight with the mass of 9.1 +/-0.1 kg freely falls onto the steel column above the center of the battery from the height of 610 +/-25 mm, and the lithium ion battery is observed for 6 hours after the test is finished, and the lithium ion battery is not fired and not exploded and is recorded as passing. Each lithium ion battery is tested by 10, the weight impact test passing rate is calculated, and the safety of the lithium ion battery is evaluated according to the weight impact test passing rate.
TABLE 1
As can be seen from table 1, the lithium ion battery prepared by using the electrode assembly in the embodiment of the present invention has a needle penetration rate of 80% and a weight impact penetration rate of 70% or more, which indicates that the electrode assembly of the present invention can improve the safety performance of the lithium ion battery.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. An electrode assembly comprising an electrode assembly body including a positive electrode tab and a negative electrode tab separated by a separator, and a first polymer layer located on at least part of the periphery of the electrode assembly body.
2. The electrode assembly of claim 1, wherein the electrode assembly is a lamination stack;
the first polymer layer covers at least one side of the electrode assembly body;
the functional surface of the first polymer layer facing the electrode assembly body is provided with a first conductive layer, and the functional surface of the first conductive layer away from the first polymer layer is provided with a positive electrode active layer.
3. The electrode assembly of claim 1, wherein the electrode assembly is in a wound structure;
the first polymer layer is located at an outermost layer of the electrode assembly body.
4. The electrode assembly according to claim 3, wherein the positive electrode tab includes a positive electrode current collector including a main body portion and an extension portion connected to each other, at least one functional surface of the main body portion having a positive electrode active layer;
the extension includes at least a first polymer layer, and the first polymer layer is located at an outermost layer of the electrode assembly body.
5. The electrode assembly of claim 4, wherein the extension portion further comprises a first conductive layer, the first conductive layer and the first polymer layer being disposed in a stack;
the main body portion includes a second conductive layer, and the first conductive layer and the second conductive layer are integrally connected.
6. The electrode assembly of claim 4, wherein the extension portion further comprises a first conductive layer, the body portion comprises a second conductive layer, the first conductive layer and the second conductive layer are connected in an overlapping manner, and a length of the overlapping portion is 5-20 mm.
7. The electrode assembly of claim 5 or 6, wherein a conductive agent and/or an adhesive is included between the first conductive layer and the first polymer layer.
8. The electrode assembly of claim 5 or 6, wherein the body portion further comprises a second polymer layer, the second conductive layer being located on at least one functional surface of the second polymer layer, the second conductive layer being provided with a positive active layer away from the functional surface of the second polymer layer.
9. The electrode assembly of claim 8, wherein the first polymer layer and the second polymer layer are integrally or separately connected.
10. A lithium ion battery comprising the electrode assembly of any one of claims 1-9.
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Application publication date: 20211126 |