CN115642294A - Battery cell and battery - Google Patents
Battery cell and battery Download PDFInfo
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- CN115642294A CN115642294A CN202211422333.4A CN202211422333A CN115642294A CN 115642294 A CN115642294 A CN 115642294A CN 202211422333 A CN202211422333 A CN 202211422333A CN 115642294 A CN115642294 A CN 115642294A
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- 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
Abstract
The invention provides a battery core and a battery. The battery cell is formed by winding a positive plate, a first diaphragm, a negative plate and a second diaphragm which are sequentially stacked, wherein the length of at least one of the first diaphragm and the second diaphragm is shorter than that of the negative plate and the positive plate, and a tail section with one or two layers of diaphragms missing is formed at the tail part of the battery cell; the ending section comprises at least one group of surface contact areas directly opposite to the positive plate and the negative plate, the surface contact areas on the negative plate are arranged to be empty foil areas, the surface contact areas on the positive plate are arranged to be glue coating areas, the glue coating areas comprise a positive current collector and an insulating polymer glue layer coated on the surface of the positive current collector, and the initial melting temperature of the polymer glue layer is not greater than the initial thermal runaway temperature of the battery. The battery core can preset the priority of the thermal runaway short circuit mode, so that the battery can autonomously trigger the contact short circuit mode of the positive current collector and the negative current collector under the condition of higher environmental temperature, the heat generation is reduced, and the safety performance of the battery in the abusive heat is improved.
Description
Technical Field
The invention belongs to the field of batteries, and relates to a battery core and a battery.
Background
Along with the development of the society, the demand of people on portable mobile office equipment is more and more urgent, and the lithium ion battery has the characteristics of high energy density, high power density, good cycle performance, no memory effect, environmental protection and the like, so that the lithium ion battery becomes an energy storage tool of the portable office equipment, is widely applied to various electronic products such as mobile phones, mobile cameras, notebook computers, mobile phones and the like, and is expected to become an energy supply system of future electric vehicles.
With the increasing demands of people on office and equipment operation, the requirements on the use environment of the lithium ion battery are higher and higher, for example, in electronic equipment operating at high temperature, the lithium ion battery is required to be capable of being stored in the high temperature environment for a long time; for example, a device requiring high-rate quick charge needs a lithium ion battery with good high-rate quick charge performance. However, under the use environments of high-temperature storage, high-rate quick charge and the like, the lithium ion battery is easy to generate heat, the phenomenon of thermal runaway occurs, and then the phenomena of fire, combustion and the like are caused. At present, the safety performance of the lithium ion battery in thermal abuse is one of the barriers that the lithium ion battery is difficult to commercialize, so how to improve the safety performance of the lithium ion battery in thermal abuse is a technical problem to be solved urgently in the field.
Disclosure of Invention
The invention provides a battery cell, which has excellent safety performance during heat abuse by specially designing the battery cell.
The present invention also provides a battery having excellent safety performance upon thermal abuse, since the battery includes the above-described cell.
The invention provides a battery cell, which is formed by winding a positive plate, a first diaphragm, a negative plate and a second diaphragm which are sequentially stacked, wherein the length of at least one of the first diaphragm and the second diaphragm is shorter than that of the negative plate and the positive plate, and a tail section missing one or two layers of diaphragms is formed at the tail part of the battery cell; the ending section comprises at least one group of positive plate and the direct relative surface contact zone of negative plate, on the negative plate the surface contact zone sets up to empty foil district, the surface contact zone on the positive plate sets up to the rubber coating district, the rubber coating district includes the anodal mass flow body and coats the insulating polymer glue film on anodal mass flow body surface, the initial melting temperature of polymer glue film is not more than the initial thermal runaway temperature of battery.
The battery core is characterized in that the initial melting temperature of the polymer adhesive layer is 110-125 ℃, and the complete melting temperature is 130-140 ℃;
and/or the polymer adhesive layer is selected from at least one of styrene thermoplastic elastomer, thermoplastic polyurethane, polyolefin dynamic vulcanized elastomer, multi-layer co-extruded polyolefin heat shrinkable film, oriented polystyrene, thermoplastic polyurethane elastomer rubber, thermoplastic vulcanized rubber and thermoplastic polyolefin elastomer.
A battery cell as described above, wherein a coverage area of the polymer glue layer extends between the first separator and/or the second separator and the positive electrode tab.
The battery core is characterized in that the length of the overlapping area of the polymer adhesive layer and the first diaphragm and/or the second diaphragm is 5-10 mm.
The battery core is characterized in that the thickness of the polymer adhesive layer is 5-20 μm.
The battery cell is characterized in that the length of the empty foil area of the negative electrode plate is 1/4-2/3 of the width of the battery cell.
The battery core is characterized in that the tail part of the positive plate exceeds the tail part of the negative plate;
and/or the length of the tail part of the positive plate exceeding the tail part of the negative plate is 5-15 mu m.
The battery cell as described above, wherein a separator tail portion between the polymer adhesive layer and the negative electrode sheet exceeds a negative active layer tail portion of the negative electrode sheet;
and/or the length of the tail part of the diaphragm between the polymer glue layer and the negative plate, which exceeds the tail part of the negative active layer of the negative plate, is 5-15 mu m.
The battery core is provided with the insulating gummed paper on the polymer gummed layer corresponding to the tail part of the negative plate.
In a second aspect, the invention provides a battery, which includes the battery cell provided in the first aspect.
The implementation of the invention has at least the following advantages:
1) The battery core structure is specially designed, so that the priority of the thermal runaway short circuit mode can be preset, the battery can autonomously trigger the contact short circuit mode of the positive current collector and the negative current collector under the condition of higher environmental temperature, the heat generation is reduced, and the safety performance of the battery in the abuse of heat is improved.
2) The battery of the present invention has excellent safety against heat abuse due to the inclusion of the above-described cell.
Drawings
Fig. 1 is a schematic diagram of a cell structure according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a cell structure according to another embodiment of the present invention;
fig. 3 is a schematic diagram of a cell structure according to still another embodiment of the present invention;
fig. 4 is a schematic diagram of a cell structure of comparative example 1 of the present invention.
Description of reference numerals:
100-positive plate; 200-a first membrane; 300-a negative plate; 400-a second membrane; 500-a polymer glue layer; 600-insulating gummed paper; 101-a gluing area; 102-a positive electrode current collector; 103-positive electrode active layer; 301-empty foil area; 302-a negative current collector; 303-negative 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 obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
A first aspect of the present invention provides a battery cell, fig. 1 is a schematic diagram of a battery cell according to an embodiment of the present invention, fig. 2 is a schematic diagram of a battery cell according to another embodiment of the present invention, fig. 3 is a schematic diagram of a battery cell according to another embodiment of the present invention, as shown in fig. 1 to fig. 3, the battery cell according to the present invention is formed by winding a positive plate 100, a first diaphragm 200, a negative plate 300, and a second diaphragm 400, which are sequentially stacked, at least one of the first diaphragm 200 and the second diaphragm 400 has a shorter length than the negative plate 300 and the positive plate 100, and a tail portion of the battery cell has a tail portion with one or two layers of diaphragms missing; the ending section comprises at least one group of surface contact areas directly opposite to the positive plate 100 and the negative plate 300, the surface contact area on the negative plate 300 is set to be an empty foil area 301, the surface contact area on the positive plate 100 is set to be a glue coating area 101, the glue coating area 101 comprises a positive current collector 102 and an insulated polymer glue layer 500 coated on the surface of the positive current collector 102, and the initial melting temperature of the polymer glue layer 500 is not greater than the initial thermal runaway temperature of the battery.
It should be noted that, the tail portion in the present invention refers to an end away from the center of the battery cell.
Because the ending section of the battery core at least comprises a group of surface contact areas directly opposite to the positive plate 100 and the negative plate 300, the surface contact area of the negative plate 300 is a hollow foil area 301, and the surface contact area of the positive plate is a glue coating area 101, when the battery is in thermal abuse, because the initial melting temperature of the polymer glue layer 500 on the glue coating area 101 is not more than the initial thermal runaway temperature of the battery, before the thermal runaway of the battery occurs, the polymer glue layer 500 melts first to expose the positive current collector 102, and the exposed positive current collector 102 contacts with the negative current collector to automatically cause short circuit, thereby reducing the voltage of the lithium ion battery under the condition of higher temperature, reducing heat production and ensuring the safety performance of the battery in thermal abuse.
Generally, lithium ion batteries have four short circuit modes after thermal runaway is initiated: the method comprises the following steps of positive electrode material-negative electrode material contact short circuit, positive electrode material-negative electrode current collector contact short circuit, negative electrode material-positive electrode current collector contact short circuit and positive electrode current collector-negative electrode current collector contact short circuit, wherein the most dangerous is negative electrode material-positive electrode current collector contact short circuit under high temperature and high voltage, and once the short circuit occurs, a large amount of heat is inevitably generated to cause thermal runaway. According to the invention, through the design, the priority of the thermal runaway short circuit mode is preset, when the battery works normally, the polymer adhesive layer 500 plays a role in isolating the positive current collector 102 and the negative current collector 302, so that the positive current collector and the negative current collector are ensured not to be in contact with each other to generate short circuit, when the temperature of the battery is increased due to thermal abuse, the polymer adhesive layer 500 is melted, and the contact short circuit between the positive current collector and the negative current collector with the lowest danger level is automatically caused, so that the voltage is rapidly reduced, the battery stops working, and the thermal runaway phenomenon is avoided.
In the battery core of the invention, the positive plate 100 is positioned at the outermost ring of the battery core, and the battery core is usually packaged by an aluminum plastic film, so that the aluminum plastic film and the negative current collector 302 can be prevented from contacting and short-circuiting by positioning the positive plate 100 at the outermost ring of the battery core, and the safety performance of the battery is improved.
Further, in order to avoid short circuit caused by contact between the aluminum plastic film and the negative electrode current collector 302 during packaging, the tail portion of the positive electrode tab 100 exceeds the tail portion of the negative electrode tab 300. And controlling the length of the tail part of the positive plate 100 exceeding the tail part of the negative plate 300 to be 5-15 mu m in consideration of the manufacturing process.
In the embodiment shown in fig. 1, the length of the first separator 200 is shorter than that of the negative electrode sheet 300 and the positive electrode sheet 100, so that the tail portion of the battery cell forms a missing ending section of the first separator 200, the ending section includes a surface contact area directly opposite to the outermost positive electrode sheet 100 and the outermost negative electrode sheet 300, the surface contact area of the outermost negative electrode sheet 300 is an empty foil area 301, and the surface contact area of the outermost positive electrode sheet 100 includes the positive electrode current collector 102 and the polymer adhesive layer 500 disposed on a side surface of the positive electrode current collector 102 close to the first separator 200.
In addition, in the embodiment shown in fig. 1, the ending of the second separator 400 is later than the ending of the negative electrode tab 300 and earlier than the positive electrode tab 100, so that the positive electrode collector 102 of the positive electrode tab of the next outer circle without the polymer adhesive layer 500 is separated from the negative electrode collector 302 by the second separator 400, thereby avoiding the occurrence of the short circuit phenomenon caused by the contact of the positive and negative electrode collectors during the normal operation of the battery and further ensuring the safety performance of the battery. The ending part of the second separator 400 is controlled to be longer than the length of the ending part of the negative electrode tab 300 by a distance of 3 to 10 μm for safety and reliability.
In the embodiment shown in fig. 2, the length of the second separator 400 is shorter than that of the negative electrode sheet 300 and the positive electrode sheet 100, so that the tail portion of the battery cell forms a ending section of the second separator 400, the ending section includes a surface contact region directly opposite to the positive electrode sheet 100 on the next outer circle and the negative electrode sheet 300 on the outermost circle, the surface contact region of the negative electrode sheet 300 on the outermost circle is an empty foil region 301, and the surface contact region of the positive electrode sheet 100 on the next outer circle includes the positive electrode current collector 102 and the polymer adhesive layer 500 disposed on a side surface of the positive electrode current collector 102 close to the second separator 400.
In addition, in the embodiment shown in fig. 2, the ending of the first separator 200 is later than the ending of the negative electrode sheet 300 and earlier than the positive electrode sheet 100, so that the positive electrode collector 102 of the outermost positive electrode sheet without the polymer adhesive layer 500 is separated from the negative electrode collector 302 by the first separator 200, thereby avoiding the occurrence of the short circuit phenomenon caused by the contact of the positive and negative electrode collectors during the normal operation of the battery, and further ensuring the safety performance of the battery. The ending part of the first separator 200 is controlled to be longer than the length of the ending part of the negative electrode tab 300 by a distance of 3 to 10 μm for safety and reliability.
In the embodiment shown in fig. 3, the lengths of the first separator 200 and the second separator 400 are shorter than those of the negative electrode sheets 300 and the positive electrode sheets 100, so that the tails of the cells form a final segment in which the first separator 200 and the second separator 400 are both missing, the final segment includes two sets of surface contact areas of the positive electrode sheets and the negative electrode sheets, the positive electrode sheet 100 and the negative electrode sheet 300 in the outermost circle are directly opposite and the positive electrode sheet 100 and the negative electrode sheet 300 in the next outermost circle are directly opposite, the surface contact area of the negative electrode sheet 300 in the outermost circle is an empty foil area 301, the surface contact area of the positive electrode sheet 100 in the next outermost circle includes the positive electrode current collector 102 and a polymer adhesive layer 500 disposed on a side surface of the positive electrode current collector 102 close to the first separator 200, and the surface contact area of the positive electrode sheet 100 in the next outermost circle includes the positive electrode current collector 102 and a polymer adhesive layer 500 disposed on a side surface of the positive electrode current collector 102 close to the second separator 400.
In the embodiments shown in fig. 1 to 3, the polymer glue layer 500 is connected to the positive electrode active layer 103, but the present invention is not limited to this arrangement, and the polymer glue layer 500 may not be connected to the positive electrode active layer 103.
Generally, the initial thermal runaway temperature of the battery is 120-140 ℃, the initial melting temperature of the polymer adhesive layer 500 of the present invention is 110-125 ℃, and the complete melting temperature is 130-140 ℃. The polymer adhesive layer 500 begins to shrink and melt at 110-125 ℃ to expose the positive current collector 102; when the temperature reaches above 130-140 ℃, the polymer adhesive layer 500 is completely melted to fully expose the positive current collector 102, so that the positive current collector 102 and the negative current collector 302 are fully contacted to cause short circuit, the voltage of the battery is sharply reduced, the heat production is reduced, and the heat abuse passing rate of the lithium ion large battery is improved.
Specifically, the material of the polymer adhesive layer 500 of the present invention may be at least one selected from styrene-based thermoplastic elastomer (TPE), thermoplastic polyurethane (TPE-U), polyolefin dynamically vulcanized elastomer (TPE-V), multi-layer co-extruded polyolefin heat shrinkable film (POF), oriented polystyrene (OPS shrink film), thermoplastic polyurethane elastomer rubber (TPU), thermoplastic vulcanizate (TPV), and thermoplastic polyolefin elastomer (TPO).
Further, in addition to the glue coating area 101 disposed on the surface contact area of the positive electrode sheet 100, the covering area of the polymer glue coating layer 500 of the present invention also extends from the surface contact area to between the first separator 200 and/or the second separator 400 and the positive electrode sheet 100. Specifically, when the length of the first separator 200 is shorter than the negative electrode tab 300 and the positive electrode tab 100, the coverage area of the polymer adhesive layer 500 thereof extends from the surface contact area to between the first separator 200 and the positive electrode tab 100; when the length of the second separator 400 is shorter than the negative electrode tab 300 and the positive electrode tab 100, the coverage area of the polymer glue layer 500 thereof extends from the surface contact area to between the second separator 400 and the positive electrode tab 100; when the first and second separators 200 and 400 are shorter than the negative and positive electrode tabs 300 and 100, the coverage area of the polymer glue layer 500 thereof extends from the surface contact area to between the first and second separators 200 and 400 and the positive electrode tab 100.
It is understood that the extension length of the polymer gel layer 500 is not too long, so as to avoid occupying too much positive active material coating area, which adversely affects the energy density of the battery. Preferably, the length of the overlapped region of the extended polymer glue layer 500 and the first separator 200 and/or the second separator 400 is controlled to be 5 to 10mm.
It is understood that the thickness of the polymer glue layer 500 also has an influence on the insulation performance, and it is found that when the thickness of the polymer glue layer 500 reaches 5 μm, the insulation glue layer 400 is not broken down under the applied voltage of 10V. In consideration of the insulation performance and the manufacturing cost of the polymer adhesive layer 500, the thickness of the polymer adhesive layer 500 is controlled to be 5-20 μm.
In order to have a sufficient short-circuit area, the length of the empty foil area 301 of the negative electrode sheet 300 of the present invention is 1/4 to 2/3 of the width of the cell.
In order to avoid short circuit caused by contact between the polymer adhesive layer 500 and the negative active layer 303 after melting, the tail of the separator between the polymer adhesive layer 500 and the negative plate 300 should be controlled to exceed the tail of the negative active layer of the negative plate 300. Preferably, the length of the tail part of the separator between the polymer adhesive layer 500 and the negative electrode sheet 300 exceeding the tail part of the negative electrode active layer 303 of the negative electrode sheet 300 is controlled to be 5 to 15 μm.
It should be noted that, after the battery core is wound and formed, it is required to ensure that the lengths of the negative electrode active layers 303 at the head and the tail of the battery core are respectively 2-5 mm greater than the length of the positive electrode active layer 103.
Further, an insulating adhesive tape 600 is disposed on the polymer adhesive layer 500 corresponding to the tail portion of the negative electrode tab 300. Therefore, the battery short circuit caused by the fact that burrs at the ending part of the negative electrode current collector 302 and the positive electrode current collector 102 are in short circuit in advance can be avoided.
The projection of the insulating adhesive tape 600 disposed on the polymer adhesive layer 500 on the negative electrode current collector 302 at least completely covers the ending of the negative electrode current collector 302. Preferably, the length of the overlapping region between the insulating tape 600 and the negative electrode current collector 302 is 5 to 10mm, and the length of the tail of the insulating tape 600 exceeding the tail of the negative electrode current collector 302 are 5 to 15mm.
Except that the polymer adhesive layer 500 is provided with the insulating adhesive tape 600, the ending part of the positive plate of the outermost ring is also provided with the insulating adhesive tape 600, and the insulating adhesive tape 600 extends to the current collector of the positive plate of the secondary outer ring from the ending part of the positive plate of the outermost ring so as to play a role in insulating and fixing the battery cell.
In a second aspect, the invention provides a battery, which includes the battery cell provided in the first aspect. Because the battery provided by the invention comprises the battery core, the battery has good safety during heat abuse, and the phenomenon of thermal runaway can be avoided.
Hereinafter, the battery cell and the battery provided by the present invention will be further described in detail by specific embodiments.
Example 1
1. Preparation of cell
The structure of the battery cell in this embodiment is the same as that in fig. 1, the thickness of the battery cell is 4.5mm, the width of the battery cell is 60mm, and the height of the battery cell is 85mm;
as shown in fig. 1, the battery cell of this embodiment is formed by winding a positive plate 100, a first separator 200, a negative plate 300, and a second separator 400, which are sequentially stacked, wherein the length of the first separator 200 is shorter than that of the positive plate 100 and that of the negative plate 300, so that a tail section of the battery cell, where the first separator 200 is missing, is formed at the tail of the battery cell, and the tail section includes a surface contact region where the outermost positive plate 100 and the outermost negative plate 300 are directly opposite to each other, where in the surface contact region, the negative plate 300 is a blank foil region 301, the positive plate 100 is a glue coating region 101, and the glue coating region 101 includes a positive collector 102 and a polymer glue layer 500 disposed on a surface of the positive collector 102 near the first separator 200;
the length of the empty foil area 301 of the negative plate 300 is 30mm; the tail of the positive plate 100 exceeds the tail of the negative plate 300, and the exceeding length is 10mm; the tail of the first separator 200 exceeds the tail of the negative active layer 303 on the upper surface of the negative current collector 302, and the length of the exceeding is 10mm; the tail of the second separator 400 exceeds the tail of the negative electrode sheet 300 by 5mm;
the polymer adhesive layer 500 is made of TPE-U (thermoplastic polyurethane), the initial melting temperature is 115 ℃, the complete melting temperature is 135 ℃, the thickness is 9 mu m, the polymer adhesive layer 500 is connected with the positive active layer 103, the tail part of the polymer adhesive layer 500 exceeds the tail part of the negative plate 300, and the length of the exceeding length is 5mm; the length of the overlapped area of the polymer adhesive layer 500 and the first diaphragm 200 is 12mm, the polymer adhesive layer 500 corresponding to the tail of the negative electrode plate 300 is provided with an insulating adhesive paper 600, the projection point of the tail of the negative electrode plate 300 on the insulating adhesive paper 600 is located at the middle point of the insulating adhesive paper 600, the length of the insulating adhesive paper 600 is 85mm, and the width of the insulating adhesive paper 600 is 10mm; the ending part of the outermost positive plate 100 is also provided with an insulating gummed paper 600, and the insulating gummed paper 600 extends from the ending part of the outermost positive plate 100 to the current collector of the next outer positive plate 100.
The preparation method comprises the following steps:
1) Adding a positive electrode material lithium cobaltate, a conductive agent (conductive carbon black) and a binder polyvinylidene fluoride into a stirring tank according to a mass ratio of 97.2; coating the slurry of the positive active layer on an aluminum foil current collector by using a coating machine, drying at 120 ℃, cutting, and coating a polymer adhesive layer 500 and insulating adhesive paper 600 positioned on the polymer adhesive layer 500 according to the structure of figure 1 to obtain a positive plate;
2) Adding artificial graphite serving as a negative electrode material, conductive carbon black serving as a conductive agent, styrene butadiene rubber serving as a binder and sodium carboxymethyl cellulose serving as a thickening agent into a stirring tank according to a mass ratio of 96.9; and coating the slurry of the negative active layer on a copper foil current collector by adopting a coating machine, drying at the temperature of 100 ℃, and cutting to obtain the final negative plate.
3) And sequentially laminating and winding the positive plate, the diaphragm (a PP/PE mixed diaphragm in the market) and the negative plate, and adhering the insulating adhesive paper 600 at the ending part of the positive plate according to the structure shown in the figure 1 to prepare the battery cell.
2. Preparation of lithium ion battery
And packaging the battery core by using an aluminum-plastic film, baking to remove moisture, injecting electrolyte, and forming by adopting a hot pressing forming process to obtain the lithium ion battery.
Example 2
The structure of the battery cell in this embodiment is the same as that in fig. 2, the thickness of the battery cell is 4.5mm, the width of the battery cell is 60mm, and the height of the battery cell is 85mm;
as shown in fig. 2, the battery cell of this embodiment is formed by winding a positive plate 100, a first separator 200, a negative plate 300, and a second separator 400 that are sequentially stacked, where the length of the second separator 400 is shorter than that of the positive plate 100 and the negative plate 300, so that a tail section where the second separator 400 is missing is formed at the tail of the battery cell, where the tail section includes a surface contact region where the positive plate 100 in the next outer ring and the negative plate 300 in the outermost ring are directly opposite to each other, where, in the surface contact region, the negative plate 300 is a blank region 301, the positive plate 100 is a glue coating region 101, and the glue coating region 101 includes a positive collector 102 and a polymer glue layer 500 disposed on the surface of the positive collector 102 near the second separator 400;
the length of the empty foil area 301 of the negative plate 300 is 30mm; the tail of the positive plate 100 exceeds the tail of the negative plate 300, and the exceeding length is 10mm; the tail of the second separator 400 exceeds the tail of the negative active layer 303 on the lower surface of the negative current collector 302, and the length of the excess is 10mm; the tail part of the first separator 200 exceeds the tail part of the negative electrode sheet 300, and the exceeding length is 5mm;
the polymer adhesive layer 500 is made of TPE-U (thermoplastic polyurethane), the initial melting temperature is 115 ℃, the complete melting temperature is 135 ℃, the thickness is 9 mu m, the polymer adhesive layer 500 is connected with the positive active layer 103, the tail part of the polymer adhesive layer 500 exceeds the tail part of the negative plate 300, and the exceeding length is 5mm; the length of the overlapped area of the polymer adhesive layer 500 and the second diaphragm 400 is 12mm, the polymer adhesive layer 500 corresponding to the tail of the negative electrode plate 300 is provided with the insulating adhesive paper 600, the projection point of the tail of the negative electrode plate 300 on the insulating adhesive paper 600 is located at the middle point of the insulating adhesive paper 600, the length of the insulating adhesive paper 600 is 85mm, and the width of the insulating adhesive paper 600 is 10mm; the ending part of the outermost positive plate 100 is also provided with the insulating gummed paper 600, and the insulating gummed paper 600 extends from the ending part of the outermost positive plate 100 to the current collector of the next outermost positive plate 100.
For the specific preparation methods of the battery cell and the lithium ion battery in this embodiment, reference is made to embodiment 1, and details are not repeated here.
Example 3
The structure of the battery cell in this embodiment is the same as that in fig. 3, the thickness of the battery cell is 4.5mm, the width of the battery cell is 60mm, and the height of the battery cell is 85mm;
as shown in fig. 3, the battery cell of this embodiment is formed by winding a positive plate 100, a first separator 200, a negative plate 300, and a second separator 400 that are sequentially stacked, where the lengths of the first separator 200 and the second separator 400 are both shorter than the lengths of the positive plate 100 and the negative plate 300, so that a tail section where the first separator 200 and the second separator 400 are missing is formed at the tail of the battery cell, the tail section includes a surface contact area where the outermost positive plate 100 and the outermost negative plate 300 are directly opposite to each other, and a surface contact area where the outermost positive plate 100 and the outermost negative plate 300 are directly opposite to each other, where, in the surface contact area, the negative plate 300 is a blank area 301, the outermost positive plate 100 is a glue coating area 101, the glue coating area 101 includes a positive current collector 102 and a polymer glue layer 500 disposed on a surface of the positive current collector 102 near the first separator 200, the secondary outer positive plate 100 is a glue coating area 101, and the glue coating area 101 includes the positive current collector 102 and the polymer glue layer 500 disposed on a surface of the positive current collector 102 near the second separator 400;
the length of the negative plate empty foil area 301 is 30mm; the tail part of the positive plate 100 exceeds the tail part of the negative plate 300, and the exceeding length is 10mm; the tail parts of the first separator 200 and the second separator 400 respectively exceed the tail parts of the negative active layers 303 positioned on the upper surface and the lower surface of the negative current collector 302, and the exceeding lengths are both 10mm;
the two polymer adhesive layers 500 on the battery core of the embodiment are both made of TPE-U (thermoplastic polyurethane), the initial melting temperature is 115 ℃, the complete melting temperature is 135 ℃, the thickness is 9 μm, the two polymer adhesive layers 500 are both connected with the positive electrode active layer 103, the tails of the two polymer adhesive layers 500 exceed the tails of the negative electrode sheet 300, and the excess lengths are both 5mm; the lengths of the overlapped areas of the polymer adhesive layers 500, the first diaphragm 200 and the second diaphragm 400 are both 12mm, the two polymer adhesive layers 500 corresponding to the tail of the negative plate 300 are both provided with insulating gummed paper 600, the projection points of the tail of the negative plate 300 on the two insulating gummed paper 600 are positioned at the middle point of the insulating gummed paper 600, the lengths of the two insulating gummed paper 600 are both 85mm, and the widths of the two insulating gummed paper 600 are both 10mm; the ending part of the outermost positive plate 100 is also provided with an insulating gummed paper 600, and the insulating gummed paper 600 extends from the ending part of the outermost positive plate 100 to the current collector of the next outer positive plate 100.
The specific preparation method of the battery cell and the lithium ion battery in this embodiment refers to embodiment 1, and details are not repeated here.
Comparative example 1
Fig. 4 is a schematic diagram of a cell structure of comparative example 1 of the present invention, where the thickness of the cell is 4.5mm, the width of the cell is 60mm, and the height of the cell is 85mm;
as shown in fig. 4, the battery cell of the present comparative example is formed by winding a positive electrode sheet 100, a first separator 200, a negative electrode sheet 300, and a second separator 400, which are sequentially stacked, wherein the lengths of the first separator 200 and the second separator 400 are both longer than the length of the negative electrode sheet 300 and shorter than the length of the positive electrode sheet 100, so that the ending part of the battery cell presents a state of the positive electrode current collector 102 to the positive electrode current collector 102, and no empty foil exists at the ending part of the negative electrode sheet; the ending part of the outermost positive plate 100 is also provided with an insulating gummed paper 600, and the insulating gummed paper 600 extends from the ending part of the outermost positive plate 100 to the current collector of the next outer positive plate 100.
The specific preparation methods of the electric core and the lithium ion battery of the comparative example refer to example 1, and are not described herein again.
Test example
The lithium ion batteries prepared in the above examples and comparative examples were tested for thermal abuse performance by the following methods: and (3) placing the lithium ion battery in a heat box, raising the temperature to 125 ℃, 130 ℃, 135 ℃ and 140 ℃ at the rate of 2 ℃/min, keeping the temperature for 1h, and if the battery does not smoke or burn, determining that the heat abuse performance test is passed, otherwise, determining that the battery does not pass. The test results are shown in table 1.
TABLE 1
As can be seen from the table 1, the lithium ion battery prepared by the cell structure of the invention has 100% of heat abuse passing rate in heat abuse tests at 125 ℃, 130 ℃, 135 ℃ and 140 ℃; the lithium ion battery prepared by the traditional battery core structure of the comparative example 1 starts to reduce the passing rate in a heat abuse test at 130 ℃, and the battery shows the phenomenon of smoke and combustion at 135 ℃ and 140 ℃, so that the heat abuse safety performance is poor.
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. The battery cell is characterized by being formed by winding a positive plate, a first diaphragm, a negative plate and a second diaphragm which are sequentially stacked, wherein the length of at least one of the first diaphragm and the second diaphragm is shorter than that of the negative plate and the positive plate, and a tail section with one or two layers of diaphragms missing is formed at the tail part of the battery cell; the ending section comprises at least one group of positive plate and the direct relative surface contact area of negative plate, the negative plate is last the surface contact area sets up to empty foil district, the surface contact area on the positive plate sets up to the rubber coating district, the rubber coating district includes anodal mass flow body and coats the insulating polymer glue film on anodal mass flow body surface, the initial melting temperature of polymer glue film is not more than the initial thermal runaway temperature of battery.
2. The battery cell according to claim 1, wherein the polymer adhesive layer has an initial melting temperature of 110 to 125 ℃ and a complete melting temperature of 130 to 140 ℃;
and/or the polymer adhesive layer is selected from at least one of styrene thermoplastic elastomer, thermoplastic polyurethane, polyolefin dynamic vulcanized elastomer, multi-layer co-extruded polyolefin heat shrinkable film, oriented polystyrene, thermoplastic polyurethane elastomer rubber, thermoplastic vulcanized rubber and thermoplastic polyolefin elastomer.
3. The cell of claim 1 or 2, wherein a coverage area of the polymer glue layer extends between the first separator and/or the second separator and the positive electrode sheet.
4. The cell of claim 3, wherein the length of the overlapping region of the polymer gel layer and the first membrane and/or the second membrane is 5-10 mm.
5. The electrical core of any of claims 1 to 4, wherein the polymer gel layer has a thickness of 5 to 20 μm.
6. The battery cell of claim 1, wherein the length of the empty foil region of the negative electrode tab is 1/4 to 2/3 of the width of the battery cell.
7. The electrical core of any one of claims 1 to 6, wherein the tail of the positive pole piece exceeds the tail of the negative pole piece;
and/or the length of the tail part of the positive plate exceeding the tail part of the negative plate is 5-15 mu m.
8. The electrical core according to any one of claims 1 to 7, wherein a separator tail portion between the polymer adhesive layer and the negative electrode sheet exceeds a negative active layer tail portion of the negative electrode sheet;
and/or the length of the tail part of the diaphragm between the polymer glue layer and the negative plate, which exceeds the tail part of the negative active layer of the negative plate, is 5-15 mu m.
9. The electric core of any one of claims 1 to 8, wherein an insulating adhesive tape is disposed on the polymer adhesive layer corresponding to the tail portion of the negative electrode sheet.
10. A battery comprising the cell of any of claims 1-9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211422333.4A CN115642294A (en) | 2022-11-14 | 2022-11-14 | Battery cell and battery |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211422333.4A CN115642294A (en) | 2022-11-14 | 2022-11-14 | Battery cell and battery |
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| CN115642294A true CN115642294A (en) | 2023-01-24 |
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| CN202211422333.4A Pending CN115642294A (en) | 2022-11-14 | 2022-11-14 | Battery cell and battery |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116565340A (en) * | 2023-07-10 | 2023-08-08 | 宁德新能源科技有限公司 | Battery cell and electric equipment |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116565340A (en) * | 2023-07-10 | 2023-08-08 | 宁德新能源科技有限公司 | Battery cell and electric equipment |
| CN116565340B (en) * | 2023-07-10 | 2024-03-12 | 宁德新能源科技有限公司 | Battery cell and electric equipment |
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