阅读说明：本技术 锂离子电池 (Lithium ion battery ) 是由 穆艳梅 牛江浩 于 2021-08-10 设计创作，主要内容包括：本申请涉及一种锂离子电池,属于电池技术领域。锂离子电池包括极卷以及安全组件,极卷具有卷绕中心孔；安全组件被配置为设置于卷绕中心孔内,安全组件包括支撑轴、封装件和阻燃剂,封装件包覆于支撑轴的外周面,阻燃剂封装于封装件内。该锂离子电池,结构简单紧凑,安全性高。(The application relates to a lithium ion battery, and belongs to the technical field of batteries. The lithium ion battery comprises a pole roll and a safety component, wherein the pole roll is provided with a winding center hole; the safety assembly is configured to be arranged in the winding central hole, and comprises a supporting shaft, a packaging piece and a flame retardant, wherein the packaging piece is wrapped on the outer peripheral surface of the supporting shaft, and the flame retardant is packaged in the packaging piece. The lithium ion battery has a simple and compact structure and high safety.)

1. A lithium ion battery, comprising:

a pole roll having a winding center hole; and

the safety assembly is configured to be arranged in the winding central hole and comprises a supporting shaft, a packaging piece and a flame retardant, the packaging piece is wrapped on the outer peripheral surface of the supporting shaft, and the flame retardant is packaged in the packaging piece.

2. The lithium ion battery of claim 1, wherein the support shaft is a cylindrical structure with a hollow interior.

3. The lithium ion battery of claim 1, wherein the support shaft is a rigid member.

4. The lithium ion battery of claim 1, wherein the encapsulant has a melting point below 160 ℃.

5. The lithium ion battery of claim 1, wherein the material of the package is a polymer that does not react with the electrolyte.

6. The lithium ion battery of claim 1, wherein the encapsulation has an annular cavity disposed about the support shaft, the flame retardant being encapsulated within the annular cavity.

7. The lithium ion battery of claim 6, wherein the package comprises an inner layer and an outer layer, the inner layer is attached to the outer circumferential surface of the support shaft, the inner layer and the outer layer are both disposed around the support shaft, two ends of the outer layer along the axial direction of the support shaft are respectively connected to two ends of the inner layer along the axial direction of the support shaft, and the inner layer and the outer layer jointly define the annular cavity.

8. The lithium ion battery of claim 7, wherein the thickness of the inner layer is 3-10 μm, the thickness of the outer layer is 10-30 μm, and the thickness of the flame retardant is 100-200 μm.

9. The lithium ion battery of claim 1, further comprising:

the top of the shell is provided with an opening, and the pole roll is arranged inside the shell;

the cap component is arranged on the opening in a covering mode;

the negative pole utmost point ear of pole book with the bottom welding of casing, the positive pole utmost point ear of pole book with the block subassembly electricity is connected.

10. The lithium ion battery of claim 9, further comprising:

the upper insulating piece is arranged in the shell and positioned between the cap assembly and the pole roll, and the upper insulating piece is used for isolating the cap assembly from the pole roll;

the lower insulating part is arranged in the shell, the lower insulating part is positioned between the bottom of the shell and the pole roll, and the lower insulating part is used for isolating the shell and the pole roll.

Technical Field

The application relates to the technical field of batteries, in particular to a lithium ion battery.

Background

When a sharp object is punctured (such as a needle) on the outside of the lithium ion battery, or a larger extrusion force (such as extrusion) acts on the lithium ion battery, or a higher temperature (such as 160 ℃) acts on the lithium ion battery (such as thermal shock), the lithium ion battery is easy to generate thermal runaway. When the lithium ion battery is out of control due to heat, the electrolyte can be burnt, and then safety risks are caused.

Currently, most of the lithium ion batteries are used for preventing the thermal runaway combustion problem by adding a flame retardant into an electrolyte, but the flame retardant can have a very adverse effect on the cycle characteristics of the lithium ion batteries and even completely lose the cycle capacity of the lithium ion batteries.

Disclosure of Invention

The application aims to provide a lithium ion battery with high safety.

The application is realized by the following technical scheme:

in one aspect, an embodiment of the present application provides a lithium ion battery, including:

a pole roll having a winding center hole; and

the safety assembly is configured to be arranged in the winding central hole and comprises a supporting shaft, a packaging piece and a flame retardant, the packaging piece is wrapped on the outer peripheral surface of the supporting shaft, and the flame retardant is packaged in the packaging piece.

According to the lithium ion battery provided by the embodiment of the application, the safety component is arranged in the winding central hole, so that no extra space is occupied; the support is provided by the support shaft, so that the positioning of the packaging piece and the flame retardant is realized, and meanwhile, the electrode roll is prevented from being loosened and displaced; the flame retardant is packaged by the packaging piece, so that the isolation of the flame retardant and the electrolyte is realized, and the cycle characteristic of the lithium ion battery is not influenced; when a sharp object on the outside punctures the lithium ion battery, or a larger extrusion force acts on the lithium ion battery, or a higher temperature (such as 160 ℃) acts on the lithium ion battery, the packaging part is damaged (such as being scratched by a pole piece, cracked or hot-melted), and the flame retardant is released into the electrolyte, so that the safety problem caused by further thermal runaway is prevented. The lithium ion battery has a simple and compact structure and high safety.

According to some embodiments of the present application, the support shaft is a cylindrical structure with a hollow interior.

In the above aspect, the cylindrical structure can provide a passage for the gas to flow through.

According to some embodiments of the application, the support shaft is a rigid piece.

In the above scheme, the supporting shaft has better rigidity so as to provide supporting force and realize supporting and positioning of the packaging piece.

According to some embodiments of the application, the melting point of the encapsulant is less than 160 ℃.

In the scheme, the melting point of the packaging part is low, so that the packaging part is convenient to melt at a high temperature so as to release the flame retardant and quickly respond to thermal runaway or thermal shock.

According to some embodiments of the present application, the material of the package is a polymer that does not react with the electrolyte.

In the above scheme, the material of the packaging part is selected, so that the flame retardant and the electrolyte are conveniently isolated, and the normal operation of the cycle characteristic of the lithium ion battery is ensured.

According to some embodiments of the present application, the enclosure has an annular cavity disposed about the support shaft, the flame retardant being enclosed within the annular cavity.

In the scheme, the annular cavity is arranged, so that the flame retardant can be uniformly distributed.

According to some embodiments of the application, the packaging member includes an inner layer and an outer layer, the inner layer is attached to the outer peripheral surface of the supporting shaft, the inner layer and the outer layer are all arranged around the supporting shaft, the outer layer is arranged along the two ends of the supporting shaft in the axial direction and is respectively connected with the inner layer along the two ends of the supporting shaft in the axial direction, and the inner layer and the outer layer jointly define the annular cavity.

In the above scheme, the inner layer is attached to the outer peripheral surface of the supporting shaft, so that the assembly positioning of the packaging piece and the supporting shaft is realized, the flame retardant is protected through the outer layer, and the outer layer is connected with the inner layer to limit the flame retardant so as to realize the isolation of the flame retardant and electrolyte.

According to some embodiments of the present application, the thickness of the inner layer is 3-10 μm, the thickness of the outer layer is 10-30 μm, and the thickness of the flame retardant is 100-200 μm.

According to some embodiments of the present application, the lithium ion battery further comprises: the top of the shell is provided with an opening, and the pole roll is arranged inside the shell; the cap component is arranged on the opening in a covering mode; the negative pole utmost point ear of pole book with the bottom welding of casing, the positive pole utmost point ear of pole book with the block subassembly electricity is connected.

In the scheme, the opening is closed through the matching of the cap assembly and the shell, so that the electrolyte is prevented from leaking; the negative pole of the lithium ion battery is formed at the bottom of the shell by welding the negative pole lug with the bottom of the shell, the positive pole lug is electrically connected with the cap assembly, and the positive pole of the lithium ion battery is formed at the cap assembly so as to lead out the electric energy of the lithium ion battery from the negative pole and the positive pole.

According to some embodiments of the present application, the lithium ion battery further comprises: the upper insulating piece is arranged in the shell and positioned between the cap assembly and the pole roll, and the upper insulating piece is used for isolating the cap assembly from the pole roll; the lower insulating part is arranged in the shell, the lower insulating part is positioned between the bottom of the shell and the pole roll, and the lower insulating part is used for isolating the shell and the pole roll.

In the scheme, the cap component and the pole roll are isolated through the upper insulating part, so that the short circuit between the cap component and the pole roll is avoided; the bottom of the shell and the pole roll are isolated through the lower insulating part, and the bottom of the shell and the pole roll are prevented from being short-circuited.

According to some embodiments of the present application, the upper insulator is provided with a plurality of first through holes spaced around a winding center line of the pole roll.

In above-mentioned scheme, the relative both sides of insulating part are gone up through a plurality of first through-holes intercommunication to the circulation of electrolyte is convenient for annotate the liquid and is smooth and easy.

Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a schematic structural diagram of a lithium ion battery provided in an embodiment of the present application;

FIG. 2 is a schematic structural view of an upper insulator according to an embodiment of the present application;

FIG. 3 is a schematic structural diagram of a lower insulator according to an embodiment of the present application;

fig. 4 is a schematic diagram of a lithium ion battery penetration test provided in an embodiment of the present application;

fig. 5 is a time-temperature graph of the lithium ion battery puncture test of fig. 4.

Icon: 100-a lithium ion battery; 10-pole coil; 11-positive plate; 12-negative pole piece; 13-a separator; 14-positive pole tab; 15-a negative electrode tab; 16-winding the central hole; 20-a safety component; 21-supporting shaft; 22-a package; 221-inner layer; 222-an outer layer; 23-a flame retardant; 30-a housing; 31-an opening; 32-protrusions; 40-a cap assembly; 41-a cap head; 42-explosion-proof membrane; 43-connecting piece; 44-an insulating rubber ring; 50-an upper insulator; 51-a first via; 52-a first central aperture; 53-a second via; 60-lower insulation; 61-a second central aperture; 62-notch; 70-steel needle.

Detailed Description

Embodiments of the present application will be described in further detail below with reference to the drawings and examples. The following detailed description of the embodiments and the accompanying drawings are provided to illustrate the principles of the application and are not intended to limit the scope of the application, i.e., the application is not limited to the described embodiments.

In the description of the present application, it is to be noted that, unless otherwise specified, "a plurality" means two or more; the terms "upper," "lower," "inner," "outer," and the like, as used herein, refer to an orientation or positional relationship indicated for convenience in describing the present application and to simplify description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. "vertical" is not strictly vertical, but is within the tolerance of the error. "parallel" is not strictly parallel but within the tolerance of the error.

The following description is given with the directional terms as they are used in the drawings and not intended to limit the specific structure of the present application. In the description of the present application, it is also to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be directly connected or indirectly connected through an intermediate. The specific meaning of the above terms in the present application can be understood as appropriate by one of ordinary skill in the art.

A lithium ion battery according to an aspect of the present application is described below with reference to the drawings.

As shown in fig. 1 to 5, a lithium ion battery 100 according to an embodiment of the present application includes: pole roll 10 and safety assembly 20.

As shown in fig. 1, the pole roll 10 includes a positive plate 11, a negative plate 12 and a diaphragm 13, the positive plate 11, the negative plate 12 and the diaphragm 13 are wound concentrically to form a roll structure, and the pole roll 10 forms a cell of the lithium ion battery 100; the separator 13 is located between the positive electrode tab 11 and the negative electrode tab 12 to prevent the positive electrode tab 11 and the negative electrode tab 12 from being short-circuited. The positive electrode sheet 11 includes a positive electrode collector and a positive electrode active material layer, the positive electrode active material layer is applied to the surface of the positive electrode collector, and the positive electrode collector to which the positive electrode active material layer is not applied serves as a positive electrode tab 14. The negative electrode sheet 12 includes a negative electrode collector and a negative electrode active material layer, the negative electrode active material layer is coated on the surface of the negative electrode collector, and the negative electrode collector not coated with the negative electrode active material layer is a negative electrode tab 15. The separator 13 may be a base film such as a polyethylene film, a polypropylene film, or a polyethylene/polyethylene composite film, or a ceramic substance may be coated on the base film.

As shown in fig. 1, the pole roll 10 has a winding center hole 16, and the safety assembly 20 is configured to be disposed within the winding center hole 16. The safety component 20 includes a support shaft 21, a package 22, and a flame retardant 23, the package 22 is wrapped around the outer peripheral surface of the support shaft 21, and the flame retardant 23 is wrapped inside the package 22. The safety assembly 20 does not occupy additional space, and installation space is reasonably utilized. The support shaft 21 extends in the same direction as the center line of the winding center hole 16, and the support shaft 21 can support the pole roll 10 and limit the pole pieces of the pole roll 10 from loosening.

As shown in fig. 1, the package 22 covers the outer peripheral surface of the support shaft 21 to form a protective layer in the circumferential direction of the support shaft 21 and isolate the flame retardant 23 from the electrolyte. When the lithium ion battery 100 is punctured by an external sharp object, the sharp object acts on the peripheral wall of the lithium ion battery 100, which easily causes the lithium ion battery 100 to be punctured, so that the pole pieces (the general terms of the positive pole piece 11 and the negative pole piece 12) of the pole roll 10 are broken, the broken pole pieces cause internal short circuit, and meanwhile, the broken pole pieces scratch the packaging part 22, so that the flame retardant 23 is released into the electrolyte, and the effect of preventing the electrolyte from burning is achieved. When a large extrusion force acts on the lithium ion battery 100, the pole roll 10 is extruded to easily cause an internal short circuit, meanwhile, the pole roll 10 transmits the extrusion force to the packaging member 22, when the extrusion force applied to the packaging member 22 is greater than the damage force of the packaging member 22, the packaging member 22 is fractured, and the flame retardant 23 is released into the electrolyte to play a role in preventing the electrolyte from burning. When the lithium ion battery 100 is subjected to thermal shock (the temperature reaches or is higher than 160 ℃), the packaging member 22 melts, and the flame retardant 23 is released into the electrolyte, so that the combustion of the electrolyte is prevented.

The lithium ion battery 100 according to the embodiment of the application has a simple and compact structure and high safety.

It should be noted that the outer diameter of the safety assembly 20 may be smaller than the diameter of the winding central hole 16 to facilitate assembly of the safety assembly 20; however, the difference between the outer diameter of the safety unit 20 and the diameter of the winding center hole 16 is not likely to be too large, and the safety unit 20 is prevented from moving relative to the pole winding 10.

According to some embodiments of the present application, as shown in fig. 1, the lithium ion battery 100 further includes a case 30 and a cap assembly 40.

As shown in fig. 1, the housing 30 has a hollow structure, an opening 31 is formed at the top of the housing 30, and the pole winding 10 and the safety assembly 20 are disposed inside the housing 30. A cap assembly 40 is disposed over the opening 31, and the cap assembly 40 is coupled to the housing 30 to form an enclosed chamber. The inside of the case 30 is filled with an electrolyte, which may be a lithium salt organic solvent electrolyte. The negative pole tab 15 of the pole roll 10 is welded with the bottom of the shell 30, and the positive pole tab 14 of the pole roll 10 is electrically connected with the cap assembly 40.

The housing 30 may be a nickel-plated stainless steel housing, or may be a housing of other conductive metals (e.g., aluminum, copper, or alloys). The cap assembly 40 is insulated from the housing 30 to avoid short circuits. The housing 30 may be cylindrical, square, or other shape. For convenience of description, in the embodiment of the present application, as shown in fig. 1, the housing 30 is described by taking a cylindrical shape as an example.

Through the cooperation of the cap assembly 40 and the shell 30, the opening 31 is closed, so that the electrolyte is prevented from leaking, and the use safety of the battery is ensured. The negative electrode tab 15 is welded with the bottom of the shell 30, and the negative electrode of the lithium ion battery 100 is formed at the bottom of the shell 30; the positive electrode of the lithium ion battery 100 is formed at the cap assembly 40 by electrically connecting the positive electrode tab 14 with the cap assembly 40, so that the electric energy of the lithium ion battery 100 is conducted out via the negative electrode and the positive electrode.

According to some embodiments of the present application, as shown in fig. 1, the support shaft 21 is a cylindrical structure with a hollow interior. During the working process and the first charge and discharge of the lithium ion battery 100, the electrolyte undergoes a chemical reaction to generate gas; the support shaft 21, which is of a cylindrical structure, can provide a passage for the gas to flow through.

According to some embodiments of the present application, the support shaft 21 is a rigid member. The supporting shaft 21 has a good rigidity so as to provide a supporting force to support and position the package 22. The support shaft 21 may be made of stainless steel, carbon fiber, or other materials with high rigidity. Alternatively, the support shaft 21 is SUS 304.

According to some embodiments of the present application, the melting point of the encapsulant 22 is less than 160 ℃. The lower melting point of the encapsulant 22 facilitates melting of the encapsulant 22 at higher temperatures (e.g., 160 ℃) to release the flame retardant 23 and to respond quickly to thermal runaway or thermal shock.

According to some embodiments of the present disclosure, the material of the package 22 is a polymer that does not react with the electrolyte. The package 22 is not dissolved when the lithium ion battery 100 is operating normally, and avoids interfering with the cycle characteristics of the lithium ion battery 100. The material of the package 22 is selected to facilitate the isolation of the flame retardant 23 from the electrolyte, so as to ensure the normal operation of the cycle characteristics of the lithium ion battery 100.

Optionally, the material of the package 22 is polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) polymer, polymethyl methacrylate (PMMA) polymer. Wherein the melting point of polyvinylidene fluoride-hexafluoropropylene polymer and the melting point of polymethyl methacrylate polymer are both lower than 160 ℃, and the polyvinylidene fluoride-hexafluoropropylene polymer and the polymethyl methacrylate polymer can be melted at higher temperature (such as 160 ℃). Meanwhile, polyvinylidene fluoride-hexafluoropropylene polymer and polymethyl methacrylate polymer have viscosity, which can facilitate attachment of the package 22 to the support shaft 21.

According to some embodiments of the present application, the enclosure 22 has an annular cavity disposed around the support shaft 21, and the flame retardant 23 is enclosed within the annular cavity. The arrangement of the annular cavity enables even distribution of the flame retardant 23.

For example, the packing member 22 may have adhesiveness, the packing member 22 is bonded to the peripheral wall of the support shaft 21, and the annular cavity of the packing member 22 is closed by the support shaft 21 to achieve encapsulation of the flame retardant 23.

According to some embodiments of the present application, as shown in fig. 1, the package 22 includes an inner layer 221 and an outer layer 222, the inner layer 221 is attached to an outer circumferential surface of the support shaft 21, the inner layer 221 and the outer layer 222 are both disposed around the support shaft 21, both ends of the outer layer 222 in an axial direction of the support shaft 21 are connected to both ends of an inner side in the axial direction of the support shaft 21, respectively, and the inner layer 221 and the outer layer 222 together define an annular cavity. The inner layer 221 is attached to the outer peripheral surface of the support shaft 21, so that the assembly and positioning of the packaging part 22 and the support shaft 21 are realized, the outer layer 222 protects the flame retardant 23, and the outer layer 222 is connected with the inner layer 221 to limit the flame retardant 23, so that the flame retardant 23 is isolated from the electrolyte.

The packing member 22 may be made of a sticky material, the inner layer 221 wraps the outer circumferential surface of the supporting shaft 21 and is attached to the outer circumferential surface of the supporting shaft 21, and the upper and lower ends of the outer layer 222 are connected to the upper and lower ends of the inner layer 221 to form an annular cavity, so as to confine the flame retardant 23 in the annular cavity and realize isolation of the flame retardant 23.

The flame retardant 23 can be triphenyl phosphate (TPP) and has a good flame retardant effect.

According to some embodiments of the present application, the thickness of the inner layer 221 is 3-10 μm, the thickness of the outer layer 222 is 10-30 μm, and the thickness of the flame retardant 23 is 100-200 μm. The thickness of the outer layer 222 is greater than the thickness of the inner layer 221 to facilitate forming a support structure on the outside of the enclosure 22 to protect the flame retardant 23.

According to some embodiments of the present application, as shown in fig. 1, the cap assembly 40 includes a cap 41, an explosion-proof diaphragm 42, a connecting sheet 43, and an insulating rubber ring 44, the cap 41 is covered at the opening 31 of the housing 30, and the insulating rubber ring 44 is disposed between the cap 41 and the housing 30 to insulate the cap 41 from the housing 30; the explosion-proof membrane 42 is positioned on one side of the cap head 41 facing the pole roll 10, the explosion-proof membrane 42 is electrically connected with the cap head 41, and the explosion-proof membrane 42 is a metal sheet; the connecting sheet 43 is located on the side of the explosion-proof membrane 42 facing away from the cap head 41, that is, on the side of the explosion-proof membrane 42 facing the pole roll 10, the connecting sheet 43 is electrically connected to the explosion-proof membrane 42, and the connecting sheet 43 is electrically connected to the positive electrode tab 14 of the pole roll 10, so that the positive electrode tab 14 of the pole roll 10 is electrically connected to the cap head 41, and the positive electrode of the lithium ion battery 100 is formed at the cap head 41.

The explosion-proof membrane 42 is arranged between the shell 30 and the cap head 41, and a closed space is formed in the shell 30 on one side of the explosion-proof membrane 42, which is far away from the cap head 41; when the internal pressure of the lithium ion battery 100 rises to the damage force value of the explosion-proof diaphragm 42, the explosion-proof diaphragm 42 is damaged, so that the sealed space is opened, buffering the internal pressure of the lithium ion battery 100.

According to some embodiments of the present application, as shown in fig. 1, the lithium ion battery 100 further includes an upper insulator 50 and a lower insulator 60. The upper insulator 50 is arranged in the shell 30, the upper insulator 50 is positioned between the cap assembly 40 and the pole roll 10, and the upper insulator 50 is used for isolating the cap assembly 40 from the pole roll 10; lower insulator 60 is disposed within housing 30, lower insulator 60 being located between the bottom of housing 30 and pole roll 10, lower insulator 60 serving to isolate housing 30 from pole roll 10. Specifically, the pole pieces of the pole roll 10 are confined between the upper insulator 50 and the lower insulator 60, the positive electrode tab 14 penetrates through the upper insulator 50 and then is electrically connected with the cap assembly 40, the negative electrode tab 15 penetrates through the lower insulator 60 and then is electrically connected with the bottom of the shell 30, and the cap assembly 40 is insulated from the shell 30, so that short circuit is avoided.

The cap assembly 40 is isolated from the pole roll 10 through the upper insulating piece 50, so that the short circuit between the cap assembly 40 and the pole roll 10 is avoided; the bottom of the shell 30 is isolated from the pole roll 10 by the lower insulating member 60, so that the bottom of the shell 30 is prevented from being short-circuited with the pole roll 10, and the safety of the lithium ion battery 100 is improved.

According to some embodiments of the present application, as shown in fig. 1, an end of the housing 30 disposed at the opening 31 is provided with an inner concave protrusion 32, the inner concave protrusion 32 is disposed around a circumference of the housing 30, and the inner concave protrusion 32 can limit the upper insulating member 50 from moving toward the cap assembly 40, so as to perform a positioning function. The matching mode of the shell 30 and the cap assembly 40 is a buckling type, so that the assembly is convenient.

According to some embodiments of the present application, as shown in fig. 2, the upper insulator 50 is provided with a plurality of first through holes 51, and the plurality of first through holes 51 are spaced around a winding center line of the pole roll 10 (see fig. 1). As shown in fig. 1 and 2, the upper insulator 50 has a disk-like structure, for example, the upper insulator 50 may be a spacer, the upper insulator 50 has a first central hole 52, and the central axis of the upper insulator 50 is collinear with the winding center line of the pole roll 10 to facilitate the installation and positioning of the upper insulator 50. The first through hole 51 penetrates the upper insulator 50 in the thickness direction of the upper insulator 50, so that both sides of the upper insulator 50 are communicated, thereby facilitating the circulation of electrolyte and the smooth injection of electrolyte.

As shown in fig. 3, the upper insulator 50 is further provided with a second through hole 53 for the positive electrode tab 14 (see fig. 1) to pass through. The second through hole 53 may be a waist-shaped hole, so that when the positive electrode tab 14 is inserted into the second through hole 53, the position of the positive electrode tab 14 in the second through hole 53 is adjusted, and assembly is facilitated.

According to some embodiments of the present application, as shown in fig. 1 and 2, the lower insulator 60 has a second central hole 61, and the central axis of the lower insulator 60 is collinear with the winding centerline of the pole roll 10 to facilitate the installation positioning of the lower insulator 60. The lower insulator 60 is provided with a notch 62 to facilitate welding of the negative electrode tab 15 with the bottom of the casing 30 after passing through the lower insulator 60. As shown in fig. 3, the lower insulating member 60 has a disk-shaped structure, for example, the lower insulating member 60 may be a gasket, and a notch 62 is formed in a cut-away area of an edge of the lower insulating member 60.

It should be noted that the upper insulating member 50 and the lower insulating member 60 have both insulating and water-resistant properties, and the material of the upper insulating member 50 and the lower insulating member 60 may be engineering plastic material, such as PPE (polyphenylene ether).

Fig. 4 is a schematic diagram illustrating a puncturing test of the lithium ion battery 100 according to an embodiment of the present disclosure, and fig. 5 is a time-temperature graph illustrating the puncturing test of the lithium ion battery 100 of fig. 4; fig. 4 is a partial cross-sectional view of the lithium ion battery 100, mainly showing a test state diagram of the pole roll 10. According to some embodiments of the present application, as shown in fig. 4 and 5, when the lithium ion battery 100 is subjected to a needle punching (e.g., steel needle 70 punching) test, as the depth of the test steel needle into the lithium ion battery 100 increases, the pole roll 10 generates heat due to an internal short circuit, so that the temperature of the pole roll 10 as a whole increases. As shown in fig. 4, A, B, C three test points are provided, point a being a point near the lancing site, and points B and C being points away from the lancing site, where point B is near the bottom of the housing 30 and point C is near the cap assembly 40. As shown in fig. 4 and 5, when the needle-punching test is performed, the temperature is highest at the point a because the point a is a position where various damages and reactions occur, and the temperatures are lower at the points B and C. As the needling progresses, the temperature of the pole roll 10 gradually increases, and when the highest point (about 160 ℃) is reached, the package 22 melts, or the package 22 is punctured, the flame retardant 23 is released, and the flame retardant 23 absorbs heat, so that the lithium ion battery 100 no longer heats up or burns.

According to the lithium ion battery 100 of the embodiment of the application, the packaging member 22 packages the flame retardant 23, the cycle characteristics of the lithium ion battery 100 are not affected, when the lithium ion battery 100 is punctured by a sharp object, thermally shocked or extruded, the packaging member 22 is damaged, the flame retardant 23 is released, the safety problem caused by further thermal runaway is prevented, and the safety is high.

It should be noted that the features of the embodiments in the present application may be combined with each other without conflict.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.