CN116826258A - Secondary battery and electronic device comprising same - Google Patents

Secondary battery and electronic device comprising same Download PDF

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Publication number
CN116826258A
CN116826258A CN202310837353.6A CN202310837353A CN116826258A CN 116826258 A CN116826258 A CN 116826258A CN 202310837353 A CN202310837353 A CN 202310837353A CN 116826258 A CN116826258 A CN 116826258A
Authority
CN
China
Prior art keywords
insulating
layer
thickness
secondary battery
adhesive layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202310837353.6A
Other languages
Chinese (zh)
Inventor
宋正菊
李琳
郭培培
李锐
李方方
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ningde Amperex Technology Ltd
Original Assignee
Ningde Amperex Technology Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ningde Amperex Technology Ltd filed Critical Ningde Amperex Technology Ltd
Priority to CN202310837353.6A priority Critical patent/CN116826258A/en
Publication of CN116826258A publication Critical patent/CN116826258A/en
Pending legal-status Critical Current

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Classifications

    • 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
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/102—Primary casings; Jackets or wrappings characterised by their shape or physical structure
    • H01M50/105—Pouches or flexible bags
    • 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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/183—Sealing members
    • H01M50/186—Sealing members characterised by the disposition of the sealing members
    • 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
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/533—Electrode connections inside a battery casing characterised by the shape of the leads or tabs
    • 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
    • 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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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Sealing Battery Cases Or Jackets (AREA)

Abstract

The application provides a secondary battery and an electronic device comprising the same. The secondary battery includes a tab, an insulating adhesive, and a package bag. The packaging bag comprises a sealing part, and the tab penetrates through the sealing part and extends out of the packaging bag. The insulating glue is arranged on the tab. The insulating glue comprises a first insulating glue layer, a second insulating glue layer and a third insulating glue layer. The insulating adhesive comprises a first part, and the first part is an area which is overlapped with the lug in the first direction and is arranged at intervals with the sealing part. The first part comprises a first end part which is positioned in the packaging bag, and the thicknesses of the insulating adhesive, the first insulating adhesive layer, the second insulating adhesive layer and the third insulating adhesive layer are respectively h1, A1, B1, C1, 10.5 percent of h1 is less than or equal to 35 percent of h1, 90 percent of B1 is less than or equal to 500 percent of B1, C1 is more than or equal to A1, 60 percent of B1 is less than or equal to 2A1 is less than or equal to 400 percent of B1. The secondary battery of the application has good sealing effect.

Description

Secondary battery and electronic device comprising same
The application is a divisional application with the application number of 202310285926.9, the application date of 2023, 3 and 22, and the application name of 'secondary battery and electronic device comprising the same'.
Technical Field
The present application relates to the field of energy storage devices, and more particularly, to a secondary battery and an electronic device including the same.
Background
The lithium ion secondary battery has the characteristics of high energy density, long cycle life, high nominal voltage, low self-discharge rate, small volume, light weight and the like, and is widely applied to various fields of electric energy storage, portable electronic equipment, electric automobiles and the like. In order to ensure the safety performance of the secondary battery, a series of tests including an internal short circuit test, a drop test, a puncture test, etc. are required to pass before the lithium ion secondary battery leaves the factory. Among them, the drop test is a relatively severe safety test of lithium ion secondary batteries. The problems that the top seal is washed away, liquid leakage and the like easily occur at the tab after the lithium ion secondary battery falls down. Sealing effect is now generally improved by providing an insulating glue at the tab package location. However, the sealing effect between the existing insulating glue and the shell is still to be improved.
Disclosure of Invention
An object of the present application is to provide a secondary battery that can improve the packaging strength at the tab position, and an electronic device including the secondary battery.
The first aspect of the present application provides a secondary battery comprising an electrode assembly, a tab Group of Piece and packaging bag 。 The electrode assembly is accommodated in the package bag 。 The packaging bag comprises a sealing partThe electrode lug assembly comprises electrode lugs and insulating glue which are respectively arranged on two sides of the electrode lugs, and the electrode lugs are connected with the electrode assembly and extend out of the packaging bag through the sealing part. The insulating glue is connected with the electrode lug and the packaging bag. The thickness of the electrode lug is t, the thickness of the electrode lug is more than or equal to 25 mu m and less than or equal to 300 mu m, the insulating glue comprises a first insulating glue layer, a second insulating glue layer and a third insulating glue layer which are sequentially stacked along the first direction, the first insulating glue layer is connected with the electrode lug, and the third insulating glue layer is connected with the packaging bag. Along the second direction perpendicular to the first direction, the insulating adhesive comprises a first part, and the first part is an area which is overlapped with the lug in the first direction and is arranged at intervals with the sealing part. In the first end, the thickness of the insulating glue is h1, the thickness of the first insulating glue layer is A1, the thickness of the second insulating glue layer is B1, and the thickness of the third insulating glue layer is C1, 10 along the first direction . 5％h1≤B1≤35％h1，90％B1≤C1≤500％B1，C1＞A1，60％B1≤A1≤400％B1。
The secondary battery provided by the application has the advantages that the h1 is more than or equal to 10.5 percent and the B1 is less than or equal to 35 percent, so that the second insulating adhesive layer is not excessively melted or fused insufficiently when the package is heated, and the interface between the second insulating adhesive layer and the first insulating adhesive layer and the interface between the second insulating adhesive layer and the third insulating adhesive layer are caused, and the package strength is reduced due to layering; the design can avoid the problem that the fusion interface is poor due to the fact that the third insulating adhesive layer is fused excessively to enable the packaging bag to be fused with the second insulating adhesive layer, and the problem that the first insulating adhesive layer is not fused sufficiently or fused excessively to enable the bonding with the electrode lug to be poor can also be avoided, and the first insulating adhesive layer, the second insulating adhesive layer and the third insulating adhesive layer are asymmetric in thickness, and the three-layer structure with asymmetric thickness is adopted, so that the insulating adhesive layer and the packaging bag can be fused completely and have no obvious interface when being packaged, packaging strength between the insulating adhesive layer and the packaging bag is improved, sealing effect is improved, and liquid leakage risk is reduced.
According to some embodiments of the present application, 8.18A1 is greater than or equal to C1 and greater than or equal to 1.05A1, the packaging tension is greater than or equal to 5.75N, and as the thickness of the third insulating adhesive layer increases, the packaging tension increases after packaging, so that the obtained secondary battery 100 is less prone to generate liquid leakage, 8.18A1 is less than C1, and the third insulating adhesive layer, the packaging layer and the second insulating adhesive layer are insufficient to generate melting during packaging, and the packaging tension is reduced due to the interface, so that the risk of liquid leakage of the secondary battery 100 is increased. Preferably, 7A1 is larger than or equal to C1 is larger than or equal to 1.3A1, and within the range, the packaging tension is larger than or equal to 6.2N, and the secondary battery 100 obtained after packaging is less prone to leakage.
According to some embodiments of the application, 3 t.gtoreq.2h1.gtoreq.0.9 t.
According to some embodiments of the application, the insulating paste further comprises a second portion along the second direction, the second portion being a region of the insulating paste coinciding with the sealing portion in the first direction. The second part, the insulating glue includes second part first insulating glue layer, second part second insulating glue layer and second part third insulating glue layer that pile up in proper order along first direction, second part first insulating glue layer, second part second insulating glue layer and second part third insulating glue layer's thickness is A2, B2, C2 respectively.
According to some embodiments of the application, in the second portion, the thickness of the third insulating glue layer of the second portion in the first direction is C2, 92% c1.ltoreq.c2.ltoreq.98% C1.
According to some embodiments of the application, 7 μm. Gtoreq.C1.gtoreq.C2. Gtoreq.1. Mu.m.
According to some embodiments of the application, the package includes a packaging layer connected to the third insulating adhesive layer, the packaging layer having a thickness P in the first direction in a region not coinciding with the sealing portion; the total thickness of the third insulating adhesive layer and the packaging layer corresponding to the second part in the first direction is H, and H is more than or equal to 0.25 (C2+P) and less than or equal to 0.75 (C2+P).
According to some embodiments of the application, 0.29 (C2+P). Ltoreq.H.ltoreq.0.5 (C2+P).
According to some embodiments of the application, in the second portion, the thickness of the second portion first insulating adhesive layer in the first direction is A2, A1 and A2 satisfy the following formula: the thickness of the film is more than or equal to 5 mu m and more than or equal to A1-A2 and more than or equal to 0.5 mu m.
According to some embodiments of the application, in the second portion, the thickness of the second insulating glue layer of the second portion in the first direction is B2, B1 and B2 satisfy the following formula: the thickness of B1-B2 is more than or equal to 3 μm and more than or equal to 0.1 μm.
According to some embodiments of the application, the package comprises a packaging layer connected to the third insulating glue layer, wherein the thickness of the packaging bag is T and the thickness of the packaging layer in the area not overlapped with the sealing part is P along the first direction; the thickness of the portion of the tab assembly corresponding to the second portion is G and the thickness of the portion of the secondary battery corresponding to the second portion and the tab is K, wherein 2T+G- (2P+2t) x 75% < K < 2T+G- (2P+2t) x 15%.
According to some embodiments of the application, the insulating glue further comprises a third portion along the second direction, the third portion being a region where the insulating glue does not overlap the sealing portion and the tab in the first direction. In the third part, along the first direction, the insulating adhesive comprises a third part of first insulating adhesive layer, a third part of second insulating adhesive layer and a third part of third insulating adhesive layer which are sequentially stacked along the first direction, wherein the thickness of the insulating adhesive is h3, the thickness of the third part of first insulating adhesive layer is A3, the thickness of the third part of second insulating adhesive layer is B3, the thickness of the third part of third insulating adhesive layer is C3, H3 is more than or equal to 10.5 percent and less than or equal to 35 percent of H3, C3 is more than or equal to A3, C3 is more than or equal to 90 percent of B3 and less than or equal to 500 percent of B3, and A3 is more than or equal to 60 percent of B3 and less than or equal to 400 percent of B3.
According to some embodiments of the application, the tab assembly includes an adhesive area, wherein the adhesive area is a portion where insulation adhesives on two sides of the tab along the first direction are adhered to each other; along the first direction, the bonding area comprises a bonding area first insulating adhesive layer, a bonding area second insulating adhesive layer and a bonding area third insulating adhesive layer, the thickness of the bonding area is Q, the thickness of the bonding area first insulating adhesive layer is D, the thickness of the bonding area second insulating adhesive layer is B4, the thickness of the bonding area third insulating adhesive layer is C4, 10.5% (Q multiplied by 0.5) is less than or equal to 35% (Q multiplied by 0.5), C4 is more than 0.5D,90% B4 is less than or equal to 500% B4, 120% B4 is less than or equal to 800B4%.
According to some embodiments of the application, the first and third layers of insulating glue have a melting point of 80-140 ℃ and the second layer of insulating glue has a melting point of 140-200 ℃.
According to some embodiments of the application, the first, second and third layers of insulation each comprise a polymer, the polymer being one or more of polypropylene, acid modified polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate or polyethylene glycol.
According to some embodiments of the application, the first and/or third insulating glue layers further comprise a toughening modifier.
According to some embodiments of the application, the toughening modifier comprises one or more of ethylene propylene diene monomer, styrene butadiene rubber, low density polyethylene, ethylene vinyl acetate copolymer, linear low density polyethylene, nylon, polyethylene terephthalate, polycarbonate, ultra high molecular weight polyethylene.
According to some embodiments of the application, the toughening modifier content is 3% -10% based on the total mass of the first insulating glue layer; and/or the content of the toughening modifier is 3-10% based on the total mass of the third insulating adhesive layer.
According to some embodiments of the application, h 1 is 30 to 160 μm.
According to some embodiments of the application, the first insulating glue layer or the third insulating glue layer comprises a color additive.
According to some embodiments of the application, the second layer of insulating glue comprises a color additive.
According to some embodiments of the application, the color additive is carbon black or titanium dioxide.
According to some embodiments of the application, the insulating gel comprises a polymer that is one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, acid modified polypropylene, polymethyl methacrylate, or polyethylene glycol. The content of the polymer is 97% or more based on the total mass of the insulating paste.
According to some embodiments of the application, the first and third layers of insulation each comprise acid-modified polypropylene.
The second aspect of the present application also provides an electronic device comprising the above secondary battery.
Drawings
The foregoing and/or additional aspects and advantages of the application will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
fig. 1 is a schematic view of a secondary battery according to an embodiment of the present application;
FIG. 2 is a schematic cross-sectional view of the cell of FIG. 1 taken along line II-II;
FIG. 3 is a schematic cross-sectional view of an encapsulation film according to an embodiment of the present application;
FIG. 4 is a schematic cross-sectional view of an insulation paste according to an embodiment of the present application;
fig. 5 is a schematic diagram of an electronic device according to an embodiment of the application.
Description of the main reference signs
A secondary battery 100;
an electrode assembly 10;
a packaging bag 40;
a tab 20;
an insulating adhesive 30;
a first encapsulation film 41;
a second encapsulation film 42;
a receiving chamber 410;
a sealing part 420;
a third portion 301;
a second portion 302;
a first portion 303;
an encapsulation layer 401;
a metal layer 402;
a protective layer 403;
a first end 303a;
a second end 303b;
a first insulating adhesive layer 31;
a second insulating adhesive layer 32;
A third insulating adhesive layer 33;
an adhesive region 201;
an electronic device 200;
a main body 210.
Detailed Description
The following description of the embodiments of the present application will clearly and specifically describe the technical solutions of the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
Hereinafter, embodiments of the present application will be described in detail. This application may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and detailed to those skilled in the art.
In addition, the dimensions or thicknesses of various components, layers may be exaggerated in the drawings for brevity and clarity. Like numbers refer to like elements throughout. As used herein, the term "and/or," "and/or" includes any and all combinations of one or more of the associated listed items. In addition, it should be understood that when element a is referred to as "connecting" element B, element a may be directly connected to element B, or intermediate element C may be present and element a and element B may be indirectly connected to each other.
Further, the use of "may" when describing embodiments of the present application refers to "one or more embodiments of the present application".
The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of the application. As used herein, the singular is intended to include the plural as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, values, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, values, steps, operations, elements, components, and/or groups thereof.
Spatially relative terms, such as "upper" and the like, may be used herein for convenience of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that spatially relative terms are intended to encompass different orientations of the device or apparatus in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "over" other elements or features would then be oriented "below" or "beneath" the other elements or features. Thus, the exemplary term "upper" may include both upper and lower directions. It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
Referring to fig. 1 and 2, an embodiment of the present application provides a secondary battery 100 including an electrode assembly 10, a tab assembly, and a packing bag 40. The tab assembly includes a tab 20 and two insulation pastes 30 respectively disposed on two sides of the tab. The tab 20 is connected to the electrode assembly 10. The packing bag 40 covers the electrode assembly 10 and covers a portion of the tab 20, and the insulating paste 30 is disposed between the packing bag 40 and the tab 20 and connects the packing bag 40 and the tab 20. In this embodiment, the number of the tabs 20 is two, namely, a positive tab and a negative tab, and the two tabs 20 are located on the same side of the secondary battery 100 and extend out of the packaging bag 40; the number of the insulating glue 30 is four, wherein two insulating glue 30 are arranged on two opposite surfaces of one tab 20, the other two insulating glue 30 are arranged on two opposite surfaces of the other tab 20, and the two insulating glue 30 positioned on the same side of the two tabs 20 are arranged at intervals. The material of the positive electrode tab may include at least one of Ni, ti, al, ag, au, pt, F e and combinations thereof. The negative electrode ear material may include at least one of Ni, ti, cu, ag, au, pt, fe and combinations thereof. In other embodiments, two insulating pastes 30 located at the same side of two tabs 20 may be connected to each other to form a single body, and two tabs 20 may also be located at different sides of the secondary battery 100.
The electrode assembly 10 includes a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet. The electrode assembly 10 is formed by laminating or winding a positive electrode sheet, a separator, and a negative electrode sheet. The positive electrode tab and the negative electrode tab are electrically connected to the two tabs 20, respectively.
The package bag 40 includes a first package film 41 and a second package film 42 disposed opposite to each other, and the shape of the first package film 41 and the shape of the second package film 42 are matched with each other. The first and second encapsulation films 41 and 42 are coupled to each other and surround to form a receiving chamber 410, and the receiving chamber 410 is used to receive at least a portion of the electrolyte, the electrode assembly 10, the tab 20, and the insulation paste 30. The edges of the first and second encapsulation films 41 and 42 are connected to form a sealing part 420, and the sealing part 420 extends from the outer side of the receiving chamber 410 toward the side facing away from the receiving chamber 410. The sealing part 420 is a part of the package bag 40 that is sealed by a hot pressing process after the electrode assembly 10 and the electrolyte are contained therein. The tab 20 is partially received in the receiving cavity 410 and protrudes outside the package bag 40 through the sealing part 420.
Referring to fig. 2 and 3, each of the first and second encapsulation films 41 and 42 includes an encapsulation layer 401, a metal layer 402 and a protection layer 403 sequentially stacked along the first direction Z, the encapsulation layer 401 being disposed close to the electrode assembly 10, and the protection layer 403 being disposed away from the electrode assembly 10. The material of the encapsulation layer 401 is a polymer, for example, polypropylene, polyamide, etc., and the encapsulation layers 401 of the first encapsulation film 41 and the second encapsulation film 42 are connected to encapsulate the package bag 40, so as to prevent the package bag 40 from being dissolved or swelled by the organic solvent in the electrolyte, and the encapsulation layers 401 are also used for preventing the electrolyte in the electrolyte from contacting the metal layer 402 to cause corrosion of the metal layer 402. The material of the protective layer 403 is polymer resin, which is used for protecting the metal layer 402, avoiding the damage of the metal layer 402 due to the external force, preventing the air permeation of the external environment, and maintaining the inside of the secondary battery 100 in an anhydrous and anaerobic environment. The metal layer 402 is made of metal, such as aluminum, steel, etc., and is used to prevent moisture penetration from the external environment and to prevent damage to the secondary battery 100 by external forces. When the secondary battery 100 is packaged by using the packaging bag 40, the packaging film can be folded in half, and then a certain temperature (180-215 ℃) and a certain pressure (0.3-0.6 MPa) are applied to the surface of the folded packaging film by using a heat sealing head to carry out heat sealing in a certain time (1.5-3S), so that the packaging layers 401 of the packaging film are fused and connected. At this time, the innermost layer of the package bag 40 is the encapsulation layer 401.
Referring to fig. 1, along a second direction X, the insulating glue 30 includes a first portion 303, a third portion 301 and a second portion 302 that are connected to each other, where the first portion 303 is a region where the insulating glue 30 overlaps the tab 20 in the first direction Z and is spaced from the sealing portion 420, the third portion 301 is a region where the insulating glue 30 does not overlap the tab 20 and the sealing portion 420 in the first direction Z, and the second portion 302 is a region where the insulating glue 30 overlaps the sealing portion 420 in the first direction Z. The second direction X is perpendicular to the first direction Z. In this embodiment, the first direction Z is the thickness direction of the tab 20, and the second direction X is the length direction of the tab 20.
In this embodiment, the first portion 303 includes a first end 303a located inside the package 40 and a second end 303b located outside the package 40. The insulating paste 30 includes four third portions 301 distributed at four corner positions, wherein two third portions 301 are located inside the package 40 and located at both sides of the first end 303a in the third direction Y, and the other two third portions 301 are located outside the package 40 and located at both sides of the second end 303b in the third direction Y. The third direction Y is perpendicular to the first direction Z and the second direction X, and in this embodiment, the third direction Y is the width direction of the tab 20. By providing the third portion 301 and the first portion 303, the insulating paste 30 is extended inward from the sealing portion 420 into the accommodating chamber 410, so as to avoid the risk of narrowing the effective seal width due to the insulating paste 30 not extending from the sealing portion 420 into the package bag 40; and the insulating glue 30 extends outwards from the sealing part 420 to the outside of the packaging bag 40, so that the risk of pressure reduction of the edge of the packaging bag 40 during packaging is avoided, and sealing is facilitated.
Referring to fig. 2 and 4, along a first direction Z, the insulating adhesive 30 includes a first insulating adhesive layer 31, a second insulating adhesive layer 32 and a third insulating adhesive layer 33 stacked in sequence, the first insulating adhesive layer 31 is connected to the tab 20, and the third insulating adhesive layer 33 is connected to the packaging layer 401 of the packaging bag 40. The first and third insulation layers 31 and 33 function as a seal, and the second insulation layer 32 functions as a support to prevent the insulation layer 30 from being excessively melted to cause a short circuit.
In the present invention, the first portion 303, the third portion 301 and the second portion 302 each include a first insulating adhesive layer 31, a second insulating adhesive layer 32 and a third insulating adhesive layer 33, the thicknesses of the first insulating adhesive layer 31, the second insulating adhesive layer 32 and the third insulating adhesive layer 33 before packaging are approximately equal, the areas where the insulating adhesives are located are different and named differently, and in the first portion 303, the insulating adhesive includes the first insulating adhesive layer 31, the second insulating adhesive layer 32 and the third insulating adhesive layer 33; in the second portion 302, the insulating glue includes a second portion of a first insulating glue layer, a second portion of a second insulating glue layer, and a second portion of a third insulating glue layer; in the third portion 301, the insulating glue includes a third portion first insulating glue layer, a third portion second insulating glue layer, and a third portion third insulating glue layer. The thickness of the first insulating adhesive layer 31, the second insulating adhesive layer 32 and the third insulating adhesive layer 33 of the first end portion 303a is approximately equal to the thickness of the first insulating adhesive layer 31, the second insulating adhesive layer 32 and the third insulating adhesive layer 33 before the encapsulation of the insulating adhesive 30, because the first end portion 303a is not melted by heat during the encapsulation.
The tab assembly further includes an adhesive area 201, where the adhesive area 201 is a portion where the insulation pastes 30 located at both sides of the tab 20 along the first direction Z are attached to each other. The adhesive region 201 is constituted by the second portion 302 and the third portion 301 of the insulating paste 30 located on the same side of the tab 20 in the third direction Y. In the bonding region 201, the first insulating adhesive layers 31 of the two insulating adhesives 30 are bonded to constitute a first insulating adhesive layer.
In some embodiments, the melting point of the first insulating glue layer 31 and the third insulating glue layer 33 is 80-140 ℃, and the melting point of the second insulating glue layer 32 is 140-200 ℃. The first, second and third insulation layers 31, 32 and 33 may include one or more of polypropylene (PP), acid-modified polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate or polyethylene glycol. Preferably, the first and third insulating adhesive layers 31 and 33 are acid-modified polypropylene, and the second insulating adhesive layer 32 is polypropylene.
In some embodiments, the first layer 31 and/or the third layer 33 further include a toughening modifier to improve flexibility and impact properties to improve the strength of the encapsulation of the insulating gel 30 with the package 40. The toughening modifier can comprise ethylene propylene diene monomer (EPR), ethylene Propylene Diene Monomer (EPDM), styrene butadiene rubber and other rubber particles for preventing crack propagation. The toughening modifier may also include one or more of a flexible polymer, a rigid polymer, or an Ultra High Molecular Weight Polyethylene (UHMWPE) to enhance the inter-crystalline connection and obscure the inter-crystalline interface. The flexible polymer may be Low Density Polyethylene (LDPE), ethylene vinyl acetate copolymer (EVA), linear Low Density Polyethylene (LLDPE), or the like. The rigid polymer may be nylon (PA 6), polyethylene terephthalate (PET), polycarbonate (PC), or the like.
In some embodiments, the toughening modifier is ultra-high molecular weight polyethylene, and the toughening modifier is added to the first insulating glue layer 31 and/or the third insulating glue layer 33 in an amount of 3% -10%. When the addition amount of the toughening modifier is 3% -10%, the packaging strength of the insulating glue 30 and the packaging bag 40 is high. When the addition amount of the toughening modifier is excessive (more than 10%), the crystals are integrated, and layering phenomenon occurs.
In the tab assembly, the thickness of the tab 20 is t,25 μm < t < 300 μm, the thickness of the insulating paste 30 is h 1, the thickness of the first insulating paste layer 31 is A1, the thickness of the second insulating paste layer 32 is B1, and the thickness of the third insulating paste layer 33 is C1 in the first end portion 303a and the second end portion 303B along the first direction Z, wherein h1=A1+B1+C1, 10.5% of h 1 < B1 < 35% of h 1, 90% of B1 < C1 < 500% of B1, C1 > A1, 60% of B1 < A1 < 400% of B1. The tab assembly meeting the above conditions has good tightness between the tab and the insulating adhesive after sealing, and good tightness between the tab assembly and the packaging bag, and the packaging tension between the tab assembly and the packaging bag can meet the sealing requirement, so that the liquid leakage rate can be effectively reduced. When t is more than 300 mu m, the thickness of the tab 20 is too thick, so that the sealing performance is insufficient, and when t is less than 25 mu m, the tab 20 is too thin, so that the tab 20 breaks in the use process, and further safety risks are caused. The secondary battery provided by the application has the advantages that the h 1 is more than or equal to 10.5 percent and the B1 is less than or equal to 35 percent, so that the second insulating adhesive layer is not excessively melted or fused insufficiently when the package is heated, and the interface and layering between the second insulating adhesive layer and the first insulating adhesive layer 31 and the third insulating adhesive layer 33 occur, so that the package strength is reduced; 90% B1 is less than or equal to C1 is less than or equal to 500% B1, 60% B1 is less than or equal to A1 is less than or equal to 400% B1, C1 is more than A1, the third insulating adhesive layer 33 and the packaging bag 40 can be completely fused, and the first insulating adhesive layer 31 is fused and adhered to the tab 20, because the third insulating adhesive layer 33 is firstly heated and thermally fused relative to the first insulating adhesive layer during packaging, the design can avoid the problem of poor fusion interface caused by fusion between the packaging bag 40 and the second insulating adhesive layer 32 caused by overfusion of the third insulating adhesive layer 33, can also avoid poor fusion or overfusion of the first insulating adhesive layer 31 and poor adhesion between the first insulating adhesive layer 31 and the tab 20, and the first insulating adhesive layer 31, the second insulating adhesive layer 32 and the third insulating adhesive layer 33 are asymmetric in thickness, and the three-layer structure with asymmetric thickness is adopted, so that the insulating adhesive layer 30 and the packaging bag 40 can be completely fused and have no obvious interface during packaging, and the packaging strength between the insulating adhesive layer 30 and the packaging bag 40 is improved,
Sealing effect is improved, and leakage risk is reduced.
According to some embodiments of the present application, when 8.18a1 is greater than or equal to c1 is greater than or equal to 1.05a1 and the thickness C1 of the third insulating adhesive layer 33 is within the above range, the secondary battery 100 can have high packaging strength while having high insulation and corrosion resistance. With the increase of the thickness of the third insulating adhesive layer 33, the packaging tension of the secondary battery 100 after packaging increases, so that leakage is less likely to occur, and after the thickness of the third insulating adhesive layer 33 exceeds a certain range, insufficient melting and interface reduction of the packaging tension caused by the melting of the third insulating adhesive layer 33, the packaging layer 401 and the second insulating adhesive layer 32 during packaging can occur, so that the risk of leakage of the secondary battery 100 is increased. When the thickness C1 of the third insulating adhesive layer 33 is within the above range, the secondary battery 100 can have high packaging strength while having high insulating and corrosion-resistant properties. Preferably, 7A1 is greater than or equal to C1 is greater than or equal to 1.3A1, and within the range, the packaging tension is greater than or equal to 6.2N, and the secondary battery 100 obtained after packaging is less prone to leakage.
The thickness of the tab 20 in the first direction Z is t. In some embodiments, t and h 1 satisfy the following formula: 3t is more than or equal to 2h 1 is more than or equal to 0.9t. By this arrangement, the secondary battery 100 can have high packaging strength while having high insulation and corrosion resistance.
In the second portion 302, along the first direction Z, the thickness of the first insulating adhesive layer of the second portion is A2, the thickness of the second insulating adhesive layer of the second portion is B2, and the thickness of the third insulating adhesive layer of the second portion is C2. In some embodiments, 92% C1 is less than or equal to C2 is less than or equal to 98% C1, and the thickness variation of the third insulating adhesive layer of the second part is smaller before and after heat sealing, so that the packaging strength is improved. In some embodiments, 7 μm C1-C2. Gtoreq.1 μm,5 μm A1-A2. Gtoreq.0.5 μm,3 μm B1-B2. Gtoreq.0.1 μm.
The thickness of the encapsulation layer 401 in the first direction Z in the region where the package bag 40 and the sealing portion 420 do not overlap is P. That is, the thickness of the encapsulation layer 401 of the package bag 40 in the first direction Z before encapsulation is P. In the second portion 302, the encapsulation layer 401 of the package bag 40 and the second portion third insulating adhesive layer of the insulating adhesive 30 are melted by the heat-seal phase, and the total thickness of the encapsulation layer 401 and the second portion third insulating adhesive layer in the first direction Z is H. In some embodiments, 0.25 (C2+P). Ltoreq.H.ltoreq.0.75 (C2+P) is provided to fully fuse the encapsulation layer 401 of the package 40 with the third layer of the second portion of the insulating paste 30, thereby improving the encapsulation strength. Preferably, 0.29 (C2+P). Ltoreq.H.ltoreq.0.5 (C2+P).
In some embodiments, the thickness of the tab assembly corresponding to the second portion 302 of the insulating paste 30 along the first direction Z is G. The thickness of the packing bag 40 in the first direction Z is T. In the present application, the thicknesses of the first encapsulation film 41 and the second encapsulation film 42 in the first direction Z are both T. The thickness of the portion of the secondary battery 100 corresponding to the tab 20 and the second portion 302 is K in the first direction Z, wherein 2t+g- (2p+2t) ×75% < K < 2t+g- (2p+2t) ×15%.
In the third portion 301, the thickness of the insulating paste 30 is h3, the thickness of the first insulating paste layer of the third portion is A3, the thickness of the second insulating paste layer of the third portion is B3, and the thickness of the third insulating paste layer of the third portion is C3, wherein h3=a3+b3+c3, 10.5%h3.ltoreq.b3.ltoreq.35%h3, 90%b3.ltoreq.c3.ltoreq.500%b3, C3 > A3, 60%b3.ltoreq.a3.ltoreq.400%b3. In the third portion 301, C3 is greater than A3, so that the third insulating adhesive layer of the third portion and the packaging layer 401 of the packaging bag 40 can be completely fused, and because the third insulating adhesive layer of the third portion is firstly heated and thermally fused relative to the first insulating adhesive layer of the third portion during packaging, the problem of poor fusion interface caused by fusion between the packaging layer 401 and the second insulating adhesive layer of the third portion due to over-fusion of the third insulating adhesive layer of the third portion can be avoided; and the third part of the first insulating adhesive layer, the third part of the second insulating adhesive layer and the third part of the third insulating adhesive layer are asymmetric in thickness, and the three-layer structure with asymmetric thickness is adopted, so that the insulating adhesive 30 and the packaging layer 401 of the packaging bag 40 can be completely fused and have no obvious interface when in packaging, the packaging strength between the insulating adhesive 30 and the packaging bag 40 is improved, and the sealing effect is improved.
In the bonding region 201, along the first direction Z, the thickness of the bonding region 201 is Q, the thickness of the first insulating adhesive layer of the bonding region is D, the thickness of the second insulating adhesive layer of the bonding region is B4, and the thickness of the third insulating adhesive layer of the bonding region is C4, wherein 10.5% (Q×0.5) is less than or equal to B4 and less than or equal to 35% (Q×0.5), C4 is more than 0.5D,90% B4 is less than or equal to C4 and less than or equal to 500% B4, and 120% B4 is less than or equal to D and less than or equal to 800B4%.
The secondary battery provided by the application has the advantages that the secondary battery is 10.5 percent (Q multiplied by 0.5) which is more than or equal to B4 and less than or equal to 35 percent (Q multiplied by 0.5), so that the second insulating adhesive layer of the second part is not excessively melted or fused insufficiently when the package is heated, and the interfaces and layering of the second insulating adhesive layer of the second part, the first insulating adhesive layer of the second part and the third insulating adhesive layer of the second part are avoided, so that the package strength is reduced; c4 is more than 0.5D,90 percent B4 is more than or equal to C4 and less than or equal to 500 percent B4, 120 percent B4 is more than or equal to D and less than or equal to 800B 4), the second part third insulating adhesive layer and the packaging bag 40 can be completely fused, and the second part first insulating adhesive layer is fused and adhered on the tab 20, because the second part third insulating adhesive layer is firstly heated and thermally fused relative to the second part first insulating adhesive layer during packaging, the design can avoid the problem that the fusion interface is bad caused by the fusion between the packaging bag 40 and the second part second insulating adhesive layer due to the over-fusion of the second part third insulating adhesive layer, and the poor adhesion between the second part first insulating adhesive layer and the tab 20 due to the insufficient fusion or over-fusion of the second part first insulating adhesive layer and the second part third insulating adhesive layer can be avoided, and the thickness of the second part third insulating adhesive layer is asymmetric, the three-layer structure is adopted, so that the insulating adhesive 30 and the packaging bag 40 can be completely fused and no obvious interface during packaging, the packaging strength between the insulating adhesive 30 and the packaging bag 40 is improved,
Sealing effect is improved, and leakage risk is reduced.
According to the secondary battery provided by the application, the first insulating adhesive layer 31 or the third insulating adhesive layer 33 contains the color additive, the color additive is carbon black, titanium dioxide and the like, and the addition of the color additive is beneficial to distinguishing the first insulating adhesive layer 31 from the third insulating adhesive layer 33 in production, so that the battery leakage caused by the fact that the third insulating adhesive layer 33 is compounded with the tab 20 in the tab assembly compounding process is avoided. Likewise, the second portion of the first insulating adhesive layer or the second portion of the third insulating adhesive layer may be added with a color additive; the third portion of the first insulating adhesive layer or the third portion of the third insulating adhesive layer may be added with a color additive; in addition, the second insulating adhesive layer 32 may also be added with a color additive for the convenience of discrimination.
In the secondary battery provided by the application, in the insulating adhesive 30, the insulating adhesive comprises a polymer, wherein the polymer is one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, acid modified polypropylene, polymethyl methacrylate or polyethylene glycol, and the content of the polymer is more than or equal to 97 percent based on the total mass of the insulating adhesive. In this range, the first insulating adhesive layer 31 and the tab 20 can be stably bonded, and the second portion of the third insulating adhesive layer and the packaging bag 40 are stably fused, so that the leakage rate is reduced.
According to the secondary battery provided by the application, the first insulating adhesive layer 31 and the third insulating adhesive layer 33 both comprise acid-modified polypropylene, and the acid-modified polypropylene can enable the first insulating adhesive layer 31 and the tab 20 to be stably bonded.
Referring to fig. 5, an embodiment of the application further provides an electronic device 200, wherein the electronic device 200 includes a main body 210 and a secondary battery 100. The secondary battery 100 is accommodated in the main body 210. The electronic device 200 may be one of a cell phone, a tablet, and an electronic reader.
In the present application, the electronic device 200 takes a mobile phone as an example, the secondary battery 100 is disposed in the mobile phone to provide electricity to the mobile phone for the mobile phone to use, and the main body 210 is of a mobile phone structure. It is understood that in other embodiments, the electronic device 200 may have other structures, not limited to the mobile phone, tablet, and electronic reader.
The performance of the battery provided by the present application is described below by way of specific examples and comparative examples.
Example 1
The tab assembly shown in fig. 1 is formed by hot melt flat pressing of an insulating paste 30 with a thickness h 1 of 80 μm and aluminum strips and nickel strips with a thickness of 5×0.1mm, wherein the width of the insulating paste 30 on the shoulder is 2.2mm, and the distance between the two insulating pastes 30 on the same side of the tab 20 is 20mm. The width of the shoulder of the insulating paste 30 is along the third direction Y (the width direction of the tab 20), and one side edge of the insulating paste 30 exceeds the distance of the same side edge of the tab.
The tab assembly was put into a package bag 40 having a thickness T of 91 μm, and then heat-sealed with a heat-sealing head having a width of 1.5mm to obtain a secondary battery as shown in fig. 1, at a heat-sealing temperature of 205 c, a heat-sealing pressure of 0.4MPa, and a heat-sealing time of 1.5S.
Cutting the secondary battery along the width direction or the length direction of the tab 20 to obtain a sample, testing the section of the sample by using a microscope (the testing multiple is 200X) of the model VHX-5000, testing the thickness of 5-10 points uniformly distributed in each region (the first insulating adhesive layer 31, the second insulating adhesive layer 32, the third insulating adhesive layer 33, the first insulating adhesive layer, the tab assembly, the packaging layer 401 and the packaging bag 40) of the sample, recording, and taking the average value as the thickness of each layer; along the first direction, the boundary between partial elements is blurred due to heat sealing, and the thickness of each element can be measured by taking the chromatic aberration of each element as an auxiliary line; the first adhesive insulating layer is composed of two first insulating adhesive layers which are adhered to each other, and half of the thickness of the first adhesive insulating adhesive layer can be regarded as the thickness of the first insulating adhesive layer.
And (3) stripping the insulating glue 30 along the length direction of the tab 20 for the secondary battery, separating three layers of the insulating glue 30 to obtain a first insulating glue layer, a second insulating glue layer and a third insulating glue layer, and respectively performing a D SC test on the first insulating glue layer, the second insulating glue layer and the third insulating glue layer to obtain the melting point of each insulating glue layer. Wherein, the D S C curve obtained by adding the toughening modifier has more than or equal to 1 melting point, and the melting points are regarded as the melting points of the insulating adhesive layer. The dsc test was performed using a commercially available differential scanning calorimeter.
Wherein in the first portion 303, the thickness A1 of the first insulating glue layer 31 is 14.8 μm, the thickness B1 of the second insulating glue layer 32 is 15.6 μm, and the thickness C1 of the third insulating glue layer 33 is 49.6 μm, wherein b1=19.5% h 1, a1=94.87% B1, c1=317.95% B1. The thickness t of the tab 20 is 100 μm. In the second portion 302, the thickness C2 of the second portion third insulating glue layer is 48.6 μm, the total thickness H of the second portion third insulating glue layer and the encapsulation layer 401 is 38.7 μm, the thickness A2 of the second portion first insulating glue layer is 12 μm, and the thickness B2 of the second portion second insulating glue layer is 14.8 μm. The thickness G of the tab assembly corresponding to the second portion 302 of the insulation paste 30 is 260 μm, the thickness P of the encapsulation layer 401 is 35 μm, and the thickness K of the secondary battery 100 corresponding to the tab 20 and the second portion 302 is 360 μm. In the third portion 301, the thickness h3 of the insulating paste 30 is 80 μm, the thickness A3 of the first insulating paste layer of the third portion is 14.8 μm, the thickness B3 of the second insulating paste layer of the third portion is 15.6 μm, and the thickness C3 of the third insulating paste layer of the third portion is 49.6 μm. In the bonding region 201 of the tab assembly, the thickness Q of the tab assembly was 160 μm, the thickness D of the first insulating adhesive layer of the bonding region was 29.6 μm, the thickness B4 of the second insulating adhesive layer of the bonding region was 15.6 μm, and the thickness C4 of the third insulating adhesive layer of the bonding region was 49.6 μm.
The material of the first insulating adhesive layer 31 is acid-modified polypropylene, and the melting point is 123 ℃. The second insulating adhesive layer 32 is made of PP, and has a melting point of 145 ℃. The third insulation glue layer 33 comprises 95% by mass of acid-modified polypropylene and 5% by mass of UHMWPE with a melting point of 120 ℃.
The battery prepared in example 1 was subjected to a package tension test, and whether the battery leaked or not was checked visually. The package tension test specifically comprises: cutting the part of the battery corresponding to the second part of the tab and the insulating adhesive along the width direction of the tab to obtain a sample with the width of 5mm and the length of 5 cm; and clamping the sample on a high-speed rail pulling machine, fixing the tab on an upper clamp, fixing the packaging bag on a lower clamp, setting the stretching speed to 175+/-5 mm/min, lifting the sample upwards along the 180-degree direction for stripping, and reading the stripping force. The read peel force value (in N) is divided by the sample width, and the package pull force F (N/mm) of the sample is calculated.
Examples 2 to 12 and comparative examples 1 to 9 are different from example 1 in that the thickness A1 of the first insulating adhesive layer 31, the thickness B1 of the second insulating adhesive layer 32 and the thickness C1 of the third insulating adhesive layer 33 in the first portion 303 of the insulating adhesive 30 are different, and specific parameters and test results are shown in table 1.
TABLE 1
Note that: x/320 represents the number of cells in which leakage occurred among the 320 samples tested as X.
As can be seen from comparison of examples 1 to 14 and comparative examples 1 to 9, when the insulating paste satisfies 10.5% h 1.ltoreq.B1.ltoreq.35% h 1, 90% B1.ltoreq.C1.ltoreq.500% B1, C1 > A1, 60% B1.ltoreq.A1.ltoreq.400% B1 simultaneously, the packing pulling force F is not less than 5.5N/mm, and the battery leakage condition is reduced.
As can be seen from comparative examples 12, 15 to 19, 8.18A 1.gtoreq.C1.gtoreq.1.05A1, in which the packaging tension is not less than 5.75N, and the thickness C1 of the third insulating adhesive layer 33 is within the above range, the secondary battery 100 can have high packaging strength while having high insulating and corrosion resistance. With the increase of the thickness of the third insulating adhesive layer 33, the packaging tension of the secondary battery 100 after packaging increases, so that leakage is less likely to occur, and after the thickness of the third insulating adhesive layer 33 exceeds a certain range, the third insulating adhesive layer 33, the packaging layer 401 and the second insulating adhesive layer 32 will not be melted sufficiently during packaging, and the packaging tension is reduced due to the interface, so that the risk of leakage of the secondary battery 100 is increased. When the thickness C1 of the third insulating adhesive layer 33 is within the above range, the secondary battery 100 can have high packaging strength while having high insulating and corrosion-resistant properties. Preferably, 7A1 is greater than or equal to C1 is greater than or equal to 1.3A1, and within the range, the packaging tension is greater than or equal to 6.1N, and the secondary battery 100 obtained after packaging is less prone to leakage.
Examples 20 to 23 and comparative examples 10 to 11 are different from example 1 in that the thickness t of the tab 20 is different, and specific parameters and test results are shown in table 2.
TABLE 2
As shown in Table 2, the packaging tension F increases along with the increase of the ratio of 2h 1/t, and when the ratio of 3 to 2h 1/t is more than or equal to 0.9, the number of the liquid leakage batteries is 0, so that the problem of liquid leakage of the batteries is completely avoided; when 2h 1/t is less than 0.9 or 2h 1/t is more than or equal to 3, the thickness of the tab or the thicker the insulating glue is, the packaging is not facilitated, a liquid leakage channel is easy to generate in the third part 301 of the insulating glue 30, and the non-tab part of the sealing part is easy to be compressed when sealed, and the sealing is insufficient to leak liquid.
Examples 24 to 25 and comparative examples 12 to 14 are different from example 1 in that at least one of the thickness C2 of the third insulating paste layer of the second portion in the second portion 302 of the insulating paste 30 and the thickness C1 of the third insulating paste layer of the second portion in the first portion 303 of the insulating paste 30 is different, and specific parameters and test results are shown in table 3.
TABLE 3 Table 3
C1(um) C2(um) C2/C1 ratio C1-C2 F(N/nm) Leakage condition
Example 1 49.6 48.6 98％ 1 6.76 0/320
Example 24 49.6 45.6 92％ 3 6.71 0/320
Example 25 88 81 92％ 7 6.69 0/320
Comparative example 12 49.6 39.6 79.8％ 10 5.47 5/320
Comparative example 13 49.6 49.1 99％ 0.5 4.80 15/320
Comparative example 14 88 79.3 90％ 8.7 4.80 15/320
As shown in Table 3, when 92% C1.ltoreq.C2.ltoreq.98% C1 and 7 μm.gtoreq.C1-C2.gtoreq.1μm are satisfied, the number of the battery with leakage is 0, the problem of battery leakage is completely avoided, and the sealing effect is further improved. When C2 is more than 98% C1 or 1 μm is more than C1-C2, the third insulating adhesive layer 33 cannot be fused with the packaging layer 401 due to the too low compression rate, and the packaging tensile force is reduced, so that liquid leakage is caused; when C2 is less than 92% C1 or 7 mu m is less than C1-C2, the insulating adhesive 30 is excessively melted, and the sealing effect is reduced and the leakage frequency is increased due to the too small thickness.
Examples 26 to 30 and comparative examples 15 to 16 are different from example 1 in that at least one of the thickness A1 of the first insulating paste layer 31 in the first portion 303 of the insulating paste layer 30, the thickness B1 of the second insulating paste layer 32, the thickness C1 of the third insulating paste layer 33, the thickness C2 of the third insulating paste layer in the second portion 302 of the insulating paste layer 30, and the total thickness H of the third insulating paste layer and the encapsulation layer 401 in the second portion 302 is different, and specific parameters and test results are shown in table 4.
TABLE 4 Table 4
As shown in Table 4, when 0.25 (C2+P). Ltoreq.H.ltoreq.0.75 (C2+P) is satisfied, the packaging tension F is larger, the number of battery cells to be leaked is reduced, and the problem of battery leakage is improved. When H/(C2+P) < 0.25, the third insulating adhesive layer 33 and the packaging layer 401 have poor interfacial fusion due to low compression ratio, and packaging tensile force is reduced, so that liquid leakage is caused; when H/(c2+p) > 0.75, the third insulating adhesive layer 33 and the encapsulation layer 401 have a too small thickness after the hot melting and thus the sealing effect is reduced, and the leakage frequency increases.
Examples 31, 32 and comparative examples 17-18 differ from example 1 in that the thickness A2 of the first insulating adhesive layer of the second portion 302 is different, and specific parameters and test results are shown in table 5.
TABLE 5
A1(um) A2(um) A1-A2 F(N/mm) Leakage condition
Example 1 14.8 12 2.8 6.76 0/320
Example 31 14.8 14.3 0.5 6.26 2/320
Example 32 14.8 9.8 5 6.65 0/320
Comparative example 17 14.8 14.6 0.2 4.85 12/320
Comparative example 18 14.8 5.5 10.2 5.15 9/320
As shown in Table 5, when the packaging tension F is larger and the number of the battery leakage is reduced, the problem of battery leakage is solved when the packaging tension F is larger and the packaging tension is more than or equal to 5 mu m and more than or equal to A1-A2 and more than or equal to 0.5 mu m.
Examples 33 to 34 and comparative examples 19 to 20 are different from example 1 in that the thickness B2 of the second insulating adhesive layer of the second portion in the second portion 302 is different, and specific parameters and test results are shown in table 6.
TABLE 6
B1(um)B2(um) B1-B2 F(N/mm) Leakage condition
Example 1 15.614.8 0.8 6.76 0/320
Example 33 15.615.5 0.1 5.95 2/320
Example 34 15.612.7 2.9 6.63 0/320
Comparative example 19 15.68.4 7.2 5.32 8/320
Comparative example 20 15.66.4 92 4.93 10/320
As shown in Table 6, when the packaging tension F is larger and the number of the battery leakage is smaller, the battery leakage problem is improved when the packaging tension F is larger and the battery leakage is smaller and the battery leakage is not smaller than 3 mu m and not smaller than 0.1 mu m.
Examples 35 to 36 and comparative examples 21 to 22 are different from example 1 in that at least one of the thickness A1 of the first insulating adhesive layer 31, the thickness B1 of the second insulating adhesive layer 32, the thickness C1 of the third insulating adhesive layer 33, the thickness G of the portion of the tab assembly corresponding to the second portion 302 of the insulating adhesive 30, and the thickness K of the portion of the secondary battery 100 corresponding to the second portion 302 and the tab 20 in the first portion 303 of the insulating adhesive 30 is different, and specific parameters and test results are shown in table 7.
TABLE 7
As can be seen from table 7, when 2t+g- (2p+2t) ×75% < K < 2t+g- (2p+2t) ×15% is satisfied, the packaging tension F is greater, the number of battery cells leaked is reduced, and the problem of battery leakage is improved.
Examples 37 to 49 and comparative examples 23 to 31 are different from example 1 in that the thickness h3 of the third portion 301 of the insulating paste 30, the thickness A3 of the third portion first insulating paste layer 31 in the third portion 301, the thickness B3 of the third portion second insulating paste layer 32, and the thickness C3 of the third portion third insulating paste layer 33 are different from each other, and specific parameters and test results are shown in table 8.
TABLE 8
As can be seen from comparison of examples 37 to 49 and comparative examples 23 to 31, when the insulating paste 30 satisfies 10.5% h 3.ltoreq.B3.ltoreq.35% h3, 90% B3.ltoreq.C3.ltoreq.500% B3, C3 > A3, 60% B3.ltoreq.A3.ltoreq.400% B3 simultaneously, the packing pulling force F is not less than 5.5N/mm, and the battery leakage condition is reduced.
Examples 50 to 62 and comparative examples 32 to 40 are different from example 1 in that at least one of the thickness Q of the bonding region 201, the thickness D of the bonding region first insulating adhesive layer, the thickness B4 of the bonding region second insulating adhesive layer and the thickness C4 of the bonding region third insulating adhesive layer of the tab assembly is different, and specific parameters and test results are shown in table 9.
TABLE 9
As can be seen from Table 9, when 10.5% (QX0.5). Ltoreq.B4.ltoreq.35% (QX0.5), C4 > 0.5D,90% B4.ltoreq.C4.ltoreq.500% B4, 120% B4.ltoreq.D.ltoreq.800B 4% are satisfied simultaneously, the packaging pulling force F.gtoreq.5N/mm and the battery leakage condition is reduced.
Examples 63 to 68 and comparative examples 41 to 42 are different from example 1 in that the materials of the first insulating adhesive layer 31, the second insulating adhesive layer 32 and the third insulating adhesive layer 33 are different, and specific parameters and test results are shown in table 10.
Table 10
As shown in table 10, when the addition amount of the toughening modifier in the third insulating adhesive layer 33 is 3% -10%, the packaging tensile force F reaches 6.22N/mm, the number of the leakage batteries is reduced, and the problem of battery leakage is improved. When the addition amount of the toughening modifier in the first insulating adhesive layer 31 is 3-10%, the number of the battery with liquid leakage is reduced, and the problem of liquid leakage of the battery is solved; when the addition amount of the toughening modifier is not in the range of 3-10%, the number of the battery with liquid leakage can be increased, and the possibility of liquid leakage of the battery can be increased.
The foregoing disclosure is merely illustrative of the present application and is not intended to limit the application thereto, therefore, equivalent variations of the application may be made and fall within the scope of the application.

Claims (25)

1. A secondary battery includes an electrode assembly, a tab assembly, and a pouch;
the electrode assembly is accommodated in the packing bag;
the packaging bag comprises a sealing part;
the electrode lug assembly comprises electrode lugs and insulating glue which are respectively arranged at two sides of the electrode lugs, the electrode lugs are connected with the electrode assembly and extend out of the packaging bag through the sealing part, and the insulating glue is connected with the electrode lugs and the packaging bag;
The electrode lug assembly comprises an adhesion area, wherein the adhesion area is a part where insulating adhesives on two sides of the electrode lug are mutually attached along a first direction; along the first direction, the bonding area comprises a bonding area first insulating adhesive layer, a bonding area second insulating adhesive layer and a bonding area third insulating adhesive layer, the thickness of the bonding area is Q, the thickness of the bonding area first insulating adhesive layer is D, the thickness of the bonding area second insulating adhesive layer is B4, the thickness of the bonding area third insulating adhesive layer is C4, 10.5% (Q multiplied by 0.5) is less than or equal to 35% (Q multiplied by 0.5), C4 is more than or equal to 0.5D,90% B4 is less than or equal to 500% B4, 120% B4 is less than or equal to 800% B4.
2. The secondary battery according to claim 1, wherein the thickness of the tab is t,25 μm is less than or equal to t is less than or equal to 300 μm, the insulation paste comprises a first insulation paste layer, a second insulation paste layer and a third insulation paste layer which are stacked in sequence along a first direction, the first insulation paste layer is connected with the tab, and the third insulation paste layer is connected with the packaging bag; along the second direction perpendicular to the first direction, the insulating glue comprises a first part, the first part is a region where the insulating glue coincides with the tab in the first direction and is arranged at intervals with the sealing part, the first part comprises a first end part, the first end part is positioned in the packaging bag, in the first end part, the thickness of the insulating glue is h 1 along the first direction, the thickness of the first insulating glue layer is A1, the thickness of the second insulating glue layer is B1, the thickness of the third insulating glue layer is C1, C1 is more than A1, 90% of B1 is less than or equal to 500% of B1, 60% of B1 is less than or equal to A1 is less than or equal to 400% of B1.
3. The secondary battery according to claim 2, wherein 8.18A 1. Gtoreq.C1. Gtoreq.1.05A 1.
4. The secondary battery according to claim 2, wherein 7a1.gtoreq.c1.gtoreq.1.3a1.
5. The secondary battery according to claim 2, wherein 3 t.gtoreq.2h1.gtoreq.0.9 t.
6. The secondary battery according to claim 2, wherein the insulating paste further comprises a second portion, in the second direction, which is a region where the insulating paste coincides with the sealing portion in the first direction, and wherein the insulating paste comprises a second portion first insulating paste layer, a second portion second insulating paste layer, and a second portion third insulating paste layer stacked in this order in the first direction, and wherein thicknesses of the second portion first insulating paste layer, the second portion second insulating paste layer, and the second portion third insulating paste layer are A2, B2, and C2, respectively, in the first direction.
7. The secondary battery according to claim 6, wherein 92% C1-C2-98% C1.
8. The secondary battery according to claim 6, wherein 7 μm.gtoreq.C1.gtoreq.C2.gtoreq.1 μm.
9. The secondary battery according to claim 6, wherein the package bag includes a package layer connected to the third insulating adhesive layer, the package layer having a thickness P in the first direction at a region not overlapping the sealing portion; the total thickness of the third insulating adhesive layer of the second part and the packaging layer corresponding to the second part in the first direction is H, and H is more than or equal to 0.25 (C2+P) and less than or equal to 0.75 (C2+P).
10. The secondary battery according to claim 9, wherein 0.29 (C2+P). Ltoreq.H.ltoreq.0.5 (C2+P).
11. The secondary battery according to claim 6, wherein A1 and A2 satisfy the following formula: the thickness of the film is more than or equal to 5 mu m and more than or equal to A1-A2 and more than or equal to 0.5 mu m.
12. The secondary battery according to claim 6, wherein 3 μm.gtoreq.B1-B2.gtoreq.0.1 μm.
13. The secondary battery according to claim 6, wherein the package bag includes a package layer connected to the third insulating adhesive layer, the package bag having a thickness T in the first direction, and the package layer having a thickness P in a region not overlapping with the sealing portion; and along the first direction, the thickness of the part of the tab assembly corresponding to the second part is G, the thickness of the part of the secondary battery corresponding to the second part and the tab is K, wherein 2T+G- (2P+2t) x 75% < K < 2T+G- (2P+2t) x 15%.
14. The secondary battery according to claim 2, wherein the insulating paste further includes a third portion in the second direction, the third portion being a region where the insulating paste does not overlap with the sealing portion and the tab in the first direction; in the third portion, along the first direction, the insulating glue comprises a third portion first insulating glue layer, a third portion second insulating glue layer and a third portion third insulating glue layer which are stacked in sequence along the first direction, wherein the thickness of the insulating glue is h3, the thickness of the third portion first insulating glue layer is A3, the thickness of the third portion second insulating glue layer is B3, the thickness of the third portion third insulating glue layer is C3, h3 is less than or equal to 10.5% and less than or equal to 35% of h3, C3 is more than A3, C3 is less than or equal to 90% and less than or equal to 500% of B3, and A3 is less than or equal to 400% of B3.
15. The secondary battery according to claim 2, wherein the first and third insulating adhesive layers have a melting point of 80 to 140 ℃ and the second insulating adhesive layer has a melting point of 140 to 200 ℃.
16. The secondary battery according to claim 2, wherein each of the first, second and third insulating adhesive layers comprises a polymer that is one or more of polypropylene, acid-modified polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, or polyethylene glycol.
17. The secondary battery of claim 2, wherein the first and/or third insulating glue layers further comprise a toughening modifier.
18. The secondary battery of claim 17, wherein the toughening modifier comprises one or more of ethylene propylene diene monomer, styrene butadiene rubber, low density polyethylene, ethylene vinyl acetate copolymer, linear low density polyethylene, nylon, polyethylene terephthalate, polycarbonate, ultra high molecular weight polyethylene.
19. The secondary battery of claim 17, wherein the toughening modifier content is 3% -10% based on the total mass of the first insulating adhesive layer; and/or the content of the toughening modifier is 3-10% based on the total mass of the third insulating adhesive layer.
20. The secondary battery according to claim 1, wherein h 1 is 30 to 160 μm.
21. The secondary battery according to claim 1, wherein the first insulating adhesive layer or the third insulating adhesive layer contains a color additive.
22. The secondary battery according to claim 21, wherein the color additive is carbon black or titanium dioxide.
23. The secondary battery according to claim 1, wherein the insulating paste comprises a polymer, the polymer being one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, acid-modified polypropylene, polymethyl methacrylate, or polyethylene glycol, and the content of the polymer being 97% or more based on the total mass of the insulating paste.
24. The secondary battery according to claim 1 or 16, wherein the first insulating adhesive layer and the third insulating adhesive layer each comprise acid-modified polypropylene.
25. An electronic device comprising the secondary battery according to any one of claims 1 to 24.
CN202310837353.6A 2023-03-22 2023-03-22 Secondary battery and electronic device comprising same Pending CN116826258A (en)

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