Secondary battery, battery pack, and electronic device

Abstract

The utility model provides a secondary battery which comprises a shell with an opening; the cover plate assembly comprises a cover plate body and an anti-explosion valve arranged on the cover plate body, the cover plate body seals the opening, and the cover plate body and the shell form a containing cavity; the electrode assembly is arranged in the containing cavity and comprises a first end face facing the cover plate assembly and a flame-retardant part, the first end face is arranged on the electrode assembly, the electrode assembly is provided with a first electrode lug, and the first electrode lug extends out of the part, not provided with the flame-retardant part, of the first end face; the orthographic projection of the anti-explosion valve on the first end face is at least partially overlapped with the orthographic projection of the flame-retardant part on the first end face. The utility model aims to provide a secondary battery so as to at least improve the safety of the secondary battery.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of secondary batteries, battery pack and electronic device. BACKGROUND

[0002] Secondary battery is provided with explosion-proof valve on its cover plate, when the gas generated in battery reaches a certain degree, explosion-proof valve will break open and release the pressure inside battery, to prevent more serious explosion accident occurs. The design of battery at explosion-proof valve at present, although it guarantees many safety problems, but there is still a security problem in battery at explosion-proof valve in actual use. SUMMARY

[0003] In view of the problems in the related art, the utility model aims to provide a secondary battery to at least improve the safety of secondary battery.

[0004] To achieve the above object, the utility model provides a kind of secondary battery, comprising: shell, with opening;Cover plate assembly, including cover plate body and the explosion-proof valve being set on cover plate body, cover plate body closes opening and is formed with containing cavity with shell;Electrode assembly, set in containing cavity, including the first end surface facing cover plate assembly, fire retardant, set to the first end surface of electrode assembly, electrode assembly has first lug, first lug is stretched from the part of first end surface without fire retardant, the orthographic projection of explosion-proof valve on first end surface and the orthographic projection of fire retardant on first end surface at least partially overlap.

[0005] In some embodiments, the orthographic projection of explosion-proof valve on first end surface is located in the range of the orthographic projection of fire retardant on first end surface.

[0006] In some embodiments, electrode assembly has coiled first pole piece, second pole piece, diaphragm between first pole piece and second pole piece, first lug is led out from first pole piece, first end surface includes lug area and blank area arranged along the thickness direction of electrode assembly, fire retardant includes first part and second part, first part is set to blank area, second part is set to lug area, first lug is stretched from lug area, the width of first part along the width direction from first lug to second lug is greater than the width of second part.

[0007] In some embodiments, electrode assembly also has second lug led out from second pole piece, second lug is stretched from lug area, first part extends between the edge opposite first lug and second lug along the width direction, second part is set between first lug and second lug and extends to the side surface opposite along the thickness direction of electrode assembly.

[0008] In some embodiments, second part is also set to blank area, at the part between first lug and second lug along the width direction in blank area, first part is superimposed on second part.

[0009] In some embodiments, the cover plate assembly further comprises: a lower plastic located between the cover plate body and the electrode assembly, the lower plastic having a through hole, a projection of the explosion-proof valve on the first end surface at least partially overlaps a projection of the through hole on the first end surface, and the projection of the through hole on the first end surface at least partially overlaps a projection of the fireproof member on the first end surface.

[0010] In some embodiments, the accommodating cavity contains a plurality of electrode assemblies arranged in a stack, a fireproof member is attached to the first end surface of each electrode assembly, and the second part between two oppositely arranged electrode assemblies is arranged in a staggered manner.

[0011] In some embodiments, the fireproof member is a heat-resistant adhesive tape or a mica sheet.

[0012] Embodiments of the present application also provide a battery pack comprising the secondary battery of any one of the above.

[0013] Embodiments of the present application also provide an electronic device comprising the battery pack.

[0014] The beneficial technical effects of the present application are as follows:

[0015] Embodiments of the present application provide a fireproof member on the first end surface of the electrode assembly, which protects the top of the electrode assembly. When the explosion-proof valve explodes, the fireproof member can prevent high-temperature particles generated by the explosion from falling from the explosion-proof valve opening to the electrode assembly, thereby preventing the electrode assembly from being damaged and causing greater safety hazards. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0017] Figure 1 An electronic device according to an embodiment of the present application is shown.

[0018] Figure 2 A perspective view of a secondary battery according to an embodiment of the present application is shown.

[0019] Figure 3 A perspective view of a housing and a cover plate assembly of a secondary battery according to an embodiment of the present application is shown.

[0020] Figure 4 An exploded view of a cover plate assembly according to an embodiment of the present application is shown.

[0021] Figure 5 The back side of the electrode assembly according to an embodiment of this application is shown.

[0022] Figure 6 The back side of the electrode assembly according to an embodiment of this application is shown.

[0023] Figure 7 The front of the electrode assembly according to an embodiment of this application is shown.

[0024] Figure 8 The front of the electrode assembly according to an embodiment of this application is shown.

[0025] Figure 9 A top view of an electrode assembly according to an embodiment of this application is shown.

[0026] Figure 10 A top view of an electrode assembly according to an embodiment of this application is shown.

[0027] Figure 11 The back side of an electrode assembly with a flame-retardant element provided according to an embodiment of this application is shown.

[0028] Figure 12 The back side of an electrode assembly with a flame-retardant element provided according to an embodiment of this application is shown.

[0029] Figure 13 The front view of an electrode assembly with a flame-retardant component according to an embodiment of this application is shown, as well as a schematic diagram of the flame-retardant component when unfolded.

[0030] Figure 14 The front view of an electrode assembly with a flame-retardant component according to an embodiment of this application is shown, as well as a schematic diagram of the flame-retardant component when unfolded.

[0031] Figure 15 A top view of an electrode assembly with a flame-retardant element according to an embodiment of this application is shown.

[0032] Figure 16 A top view of an electrode assembly with a flame-retardant element according to an embodiment of this application is shown.

[0033] Figures 17-18 It shows the relationship with Figures 13-14 Electrode assemblies in different embodiments, wherein a second portion of two oppositely disposed electrode assemblies is misaligned. Detailed Implementation

[0034] To better understand the spirit of the embodiments of this application, the following description is based on some preferred embodiments of this application.

[0035] Embodiments of the present application will be described in detail below. Throughout the present application, like or similar components and components having like or similar functions are denoted by like reference numerals. The embodiments described herein with reference to the accompanying drawings are illustrative in nature, diagrammatic in nature, and are used to provide a basic understanding of the present application. The embodiments of the present application should not be interpreted as limiting the present application.

[0036] As used herein, the terms "approximately," "generally," "substantially," and "about" are used to describe and account for small variations. When utilized in connection with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs exactly, as well as instances in which the event or circumstance occurs with a minor approximation.

[0037] In this specification, unless specifically designated or limited, relative terms such as "central," "longitudinal," "lateral," "forward," "rearward," "rightward," "leftward," "internal," "external," "lower," "upper," "horizontal," "vertical," "above," "below," "top," "bottom," and derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the application be practiced with the particular orientation described or shown.

[0038] For ease of description, "first," "second," "third," etc. can be used herein to distinguish between different components of one figure or series of figures. "First," "second," "third," etc. are not intended to describe corresponding components.

[0039] In recent years, with the development of the lithium battery industry, square aluminum shell lithium ion batteries have been widely used in electric vehicles and energy storage fields. Although lithium ion batteries are widely used and have a large amount of use, safety accidents still occur frequently in recent years, which seriously affects the use effect of the customer end, and also causes serious personnel injury and property loss. Therefore, the safety of the battery in the customer end module pack (combined battery) and the plug-in box is still an object that needs to be focused on.

[0040] The current square aluminum shell lithium battery is in the form of top cover / cover plate and shell sealing welding, the positive and negative poles of the top cover are connected to the adapter plate by laser welding, and the adapter plate is connected to the tab of the internal electrode assembly / roll core by ultrasonic welding. In addition to the positive and negative poles and the sealed liquid injection port, the top cover also has a pressure relief valve (also known as an explosion-proof valve). When the battery produces gas or is affected by safety factors, the battery will generate gas and form a high internal pressure. When the pressure reaches a certain level, the explosion-proof valve of the battery cannot withstand the internal pressure and breaks, releasing the internal pressure of the battery and preventing more serious explosion accidents. There is a lower plastic with holes inside the position corresponding to the explosion-proof valve. On the one hand, the plastic with holes can connect the explosion-proof valve and the internal pressure of the battery, and on the other hand, when the explosion-proof valve is broken, the plastic with holes can prevent and intercept the large particle and sheet-shaped spatter of the gas and electrolyte when the explosion-proof valve is broken, preventing the spatter from falling into the module Pack or the plug-in box and causing damage and affecting other batteries and structural materials, thereby achieving a safe guarantee. At the same time, the plastic with holes can also prevent large particles from entering from the outside and ensure the safety of the internal roll core of the battery. In addition, the insulating properties of the plastic can prevent the arc (usually referring to applying sufficient voltage between two electrodes to make electrons accelerate under the action of the electric field and hit air molecules, causing the air molecules to lose electrons and become ions, and the ions to accelerate under the action of the electric field to form an electric arc) between the top of the roll core and the metal part of the top cover.

[0041] The current design of the explosion-proof valve of the top cover has ensured many safety issues, but there are still safety problems in the actual use of the battery. The plastic with holes inside the explosion-proof valve has some shortcomings. After the explosion-proof valve is broken, on the one hand, the large particle and sheet-shaped spatter are intercepted, and the intercepted objects (which may be high-temperature transition objects) will fall on the top of the roll core. The size of the hole makes it difficult to intercept the spatter and drop of high-temperature small particles generated inside and outside, which can cause serious damage to the roll core. On the other hand, the plastic cannot withstand a temperature of more than 180°C. When the battery in the module Pack explodes due to abnormality, the plastic melts or spatters, and at this time, the roll core corresponding to the position of the explosion-proof valve is exposed. At this time, the explosion-proof valve port is in communication with the outside air, and the tab and the metal end of the top cover at the explosion-proof valve port are prone to arc and cause fire and explosion. Therefore, the current design of the explosion-proof valve of the top cover has not completely solved the safety problems of the roll core after the explosion, and the current battery in actual use has relatively few measures to protect the safety of the roll core after the explosion. This situation still poses a serious safety risk to the battery.

[0042] From the above, the current battery explosion-proof valve design still has safety problems that have not been completely solved. When the battery is in the module Pack, various abnormal conditions such as overcharge, short circuit, thermal runaway, etc. can cause the explosion valve to burst. On the one hand, when the temperature is high, the injection molding glue at the top cover explosion-proof valve melts and is sprayed out of the shell at the moment of explosion. The top of the core loses a layer of protection, and the top of the core is exposed to the outside world. The top cover is connected to the positive electrode, which belongs to a high potential, and the negative electrode at the top of the core is at a low potential. In this case, the position of the top cover explosion-proof valve and the top of the core are prone to arc, ignite the electrolyte and cause fire or explosion. In addition, the presence of injection molding glue without holes can cause large particles from the outside to fall in. The particles may be high temperature or metal particles. Falling on the core can cause thermal runaway to occur prematurely, causing fire and explosion. On the other hand, if the temperature at the top cover position is not particularly high when the explosion valve bursts, the injection molding glue with holes will not be sprayed out. Some internal ejecta will also be intercepted and fall on the top of the core. Even particles can fall into the core. In addition, the injection molding glue with holes also cannot prevent small particles from falling from the outside. From the above, it can be seen that the current design of the top cover explosion-proof valve cannot completely avoid the above safety risks. In view of the above risks, further protection measures need to be taken for the core at the explosion-proof valve port.

[0043] The utility model provides a kind of electronic device 1000, the following embodiment is for the convenience of explanation, with electronic device 1000 as vehicle for example to explain. Referring to Figure 1The vehicle is internally provided with a battery pack 1002, which can be arranged at the bottom, head or tail of the vehicle body 1001. The battery pack 1002 can be used for power supply of the vehicle, for example, the battery pack 1002 can be used as the operating power supply of the vehicle. The working part of the electronic device 1000 is electrically connected with the battery pack 1002 to obtain electric energy support. The vehicle can be a fuel automobile, a gas automobile or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid automobile or a range extended automobile, but is not limited thereto. The working part is the vehicle body, the battery pack 1002 is arranged at the bottom of the vehicle body, and provides electric energy support for driving of the vehicle or operation of electrical elements in the vehicle. However, in some other embodiments, the electronic device 1000 can also be a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy and an electric tool, etc. The spacecraft includes an airplane, a rocket, a space shuttle and a spacecraft, etc. The working part can obtain electric energy from the battery pack 1002, and make corresponding working unit parts, such as a fan blade rotating unit, a dust suction working unit of a dust collector, etc. The electric toy includes a fixed or mobile electric toy, such as a game machine, an electric automobile toy, an electric ship toy and an electric airplane toy, etc. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator and an electric planer, etc. The electronic device 1000 is not specially limited in the embodiments of the present application.

[0044] Figure 2 A perspective view of a secondary battery 100 according to an embodiment of the present application is shown. Figure 3 A perspective view of a housing 10 and a cover plate assembly 20 of a secondary battery 100 according to an embodiment of the present application is shown. Figure 4 An exploded view of a cover plate assembly 20 according to an embodiment of the present application is shown. Figure 5 A back surface of an electrode assembly 31 according to an embodiment of the present application is shown. Figure 6 A back surface of an electrode assembly 32 according to an embodiment of the present application is shown. Figure 7 A front surface of an electrode assembly 31 according to an embodiment of the present application is shown. Figure 8 A front surface of an electrode assembly 32 according to an embodiment of the present application is shown. Figure 9 A top view of an electrode assembly 31 according to an embodiment of the present application is shown, Figure 10 A top view of an electrode assembly 32 according to an embodiment of the present application is shown. Figure 11 A back surface of an electrode assembly 31 provided with a flame retardant member 40 according to an embodiment of the present application is shown. Figure 12 A back surface of an electrode assembly 32 provided with a flame retardant member 40 according to an embodiment of the present application is shown. Figure 13A front view of the electrode assembly 31 provided with the flame retardant member 40 and a schematic view of the flame retardant member 40 when unfolded are shown according to an embodiment of the present application. Figure 14 A front view of the electrode assembly 32 provided with the flame retardant member 40 and a schematic view of the flame retardant member 40 when unfolded are shown according to an embodiment of the present application. Figure 15 A top view of the electrode assembly 31 provided with the flame retardant member 40 is shown according to an embodiment of the present application, Figure 16 A top view of the electrode assembly 32 provided with the flame retardant member 40 is shown according to an embodiment of the present application.

[0045] An embodiment of the present application provides a secondary battery 100, which comprises a shell 10, a cover plate assembly 20, and an electrode assembly 31 / 32. The shell 10 has an opening 12, the cover plate assembly 20 comprises a cover plate body (aluminum sheet) 22 and an explosion-proof valve 24 arranged on an explosion-proof valve port 25 of the cover plate body 22, the cover plate body 22 closes the opening 12 and forms a containing cavity 14 with the shell 10, and the electrode assembly 31 / 32 is arranged in the containing cavity 14. The secondary battery 100 is, for example, a square battery, the shell 10 comprises a bottom wall and a side wall surrounding the bottom wall, and the electrode assembly 31 / 32, electrolyte and other necessary components of the battery are arranged in the containing cavity 14. Specifically, the size of the shell 10 can be determined according to the specific size and quantity of the electrode assembly 31 / 32. The material of the shell 10 can be various, such as copper, iron, aluminum, steel, aluminum alloy, etc., and a rust-proof material such as metal nickel can be plated on the surface of the shell 10 to prevent rusting of the shell 10 after long-term use.

[0046] The cover plate assembly 20 further comprises a lower plastic 26 arranged on the inner side of the cover plate body 22 facing the electrode assembly 31 / 32, a first pole 27 passing through the cover plate body 22 and the lower plastic 26, and a second pole 28 passing through the cover plate body 22 and the lower plastic 26. The electrode assembly 31 / 32 has a wound first pole sheet, a wound second pole sheet, and a diaphragm between the first pole sheet and the second pole sheet, the end of the winding body is fixedly attached by using an insulating glue 70, a first lug 51 is led out from the first pole sheet, a second lug 52 is led out from the second pole sheet, the first lug (for example, a positive lug) 51 of the electrode assembly 31 / 32 is electrically connected to the first pole 27, and the second lug (for example, a negative lug) 52 of the electrode assembly 31 / 32 is electrically connected to the second pole 28.

[0047] An embodiment of the present application provides that the first end surface of the electrode assembly 31 / 32 facing the cover plate assembly 20 is provided with a first flame retardant member 40, Figures 5-8The first end surface of the electrode assembly 31 / 32 is provided with a fireproof member 40, the first tab 51 extends from the part of the first end surface where the fireproof member 40 is not provided, and the orthographic projection of the explosion-proof valve 24 on the first end surface at least partially overlaps the orthographic projection of the fireproof member 40 on the first end surface. The embodiments of the present application play an insulating protection role on the top of the electrode assembly 31 / 32 by providing the fireproof member 40 (for example, not shrinking at 180°C) on the first end surface of the electrode assembly 31 / 32, and when the explosion-proof valve 24 explodes, the fireproof member 40 can insulate the high-temperature particulate objects generated by the explosion-proof valve from falling to the electrode assembly 31 / 32 from the explosion-proof valve port 25, avoiding further damage to the electrode assembly 31 / 32 caused by injury and causing greater safety hazards.

[0048] In some embodiments, the fireproof member 40 is an insulator, for example, a high-temperature-resistant / heat-resistant adhesive tape

for example, can be made of polyethylene terephthalate (PET) material

[0049] The orthographic projection of the explosion-proof valve 24 on the first end surface is located within the range of the orthographic projection of the fireproof member 40 on the first end surface, that is, when the explosion valve occurs, the fireproof member 40 can completely block the high-temperature particulate objects from falling to the electrode assembly 31 / 32 from the explosion-proof valve port 25. The fireproof member 40 insulates the air at the explosion-proof valve port 25 from the electrode assembly 31 / 32 and the electrolyte, so that even if the positive and negative electrodes at the top of the electrode assembly 31 / 32 touch and generate high temperature, they cannot ignite the electrolyte due to the lack of combustion aids to cause fire.

[0050] Referring to Figure 9 、 Figure 10 、 Figures 13-16The first end surface of the electrode assembly 31 / 32 includes a tab area 60 and a blank area 62 disposed in the thickness direction of the electrode assembly 31 / 32, the flame retardant member 40 includes a first portion 41 and a second portion 42, the first portion 41 is disposed in the blank area 62, and the second portion 42 is disposed in the tab area 60. The first tab 51 and the second tab 52 extend from the tab area 60. The width of the first portion 41 in the width direction from the first tab 51 to the second tab 52 is greater than the width of the second portion 42. While improving the safety of the secondary battery 100, the flame retardant member 40 fixes the first end surface of the wound body (electrode assembly 31 / 32), avoids the loosening of the wound body, and has a wider width in the blank area 62 where no tab is present to enhance the reinforcement effect. Figure 13 and Figure 14 In the expanded view of the flame retardant member 40 shown, the flame retardant member 40 includes a horizontal portion and a vertical portion, the first portion 41 corresponds to the horizontal portion, and the second portion 42 corresponds to the vertical portion.

[0051] The first portion 41 extends in the width direction between edges opposite the first tab 51 and the second tab 52, and the second portion 42 is disposed between the first tab 51 and the second tab 52 and extends to the opposite sides of the electrode assembly 31 / 32 in the thickness direction (i.e., the front surface and the back surface shown in FIG. 1). Figure 11 and Figure 12 the back surface shown in FIG. 1, and Figure 13 and Figure 14The explosion-proof valve 24 is located between the first and second pole posts 27, 28, and if an explosion occurs, the explosion-proof valve port 25 is located in the region between the first and second pole tabs 51, 52 corresponding to the first end face, and the second portion 42 of the flame-retardant member 40 is arranged between the first and second pole tabs 51, 52 to protect this region. At the same time, the second portion 42 extends to the opposite side of the electrode assembly 31 / 32, reinforcing the first end face together with the first portion 41 to prevent the winding body from loosening. The second portion 42 is also arranged in the blank area 62, which is located between the first and second pole tabs 51, 52 in the width direction, and the first portion 41 is stacked on the second portion 42. After the electrode assembly 31 / 32 is wound and hot-pressed, the second portion 42 of the flame-retardant member 40 is attached between the first and second pole tabs 51, 52 of the electrode assembly 31 / 32, and the width of the second portion 42 is equal to the distance between the first and second pole tabs 51, 52, for example, and is attached from the front to the back of the electrode assembly 31 / 32. Then, the first portion 41 of the flame-retardant member 40 is attached to the blank area 62, and the assembly is simple. In the thickness direction of the electrode assembly 31 / 32, the size of the first portion 41 is, for example, half the thickness of the electrode assembly 31 / 32, and the subsequent assembly process of the electrode assembly 31 / 32 is completed. The accommodation cavity 14 accommodates a plurality of electrode assemblies 31 / 32 (the number is not limited to two as shown in the figure) arranged in stacks, the first pole tabs 51 of the plurality of electrode assemblies 31 / 32 are electrically connected to the first pole post 27 through the adapter piece, the second pole tabs 52 of the plurality of electrode assemblies 31 / 32 are electrically connected to the second pole post 28 through the adapter piece, and the flame-retardant member 40 is attached to the first end face of each electrode assembly 31 / 32. Preferably, as shown in Figure 17 and Figure 18 In the embodiment shown, the electrode assembly 31 and the electrode assembly 32 are stacked, and the second portion 42 between the two oppositely arranged electrode assemblies 31 / 32 is arranged in a staggered manner. Compared with the embodiment shown in Figure 13 and Figure 14 The second portion 42 between the two oppositely arranged electrode assemblies 31 / 32 is overlapped, the thickness space occupied by the flame-retardant member 40 is reduced.

[0052] The lower plastic 26 is located between the cover plate body 22 and the electrode assembly 31 / 32, and the lower plastic 26 has a through hole 260 for communicating the pressure inside the explosion-proof valve 24 and the electrode assembly 31 / 32, the orthographic projection of the explosion-proof valve 24 on the first end face at least partially overlaps the orthographic projection of the through hole 260 on the first end face, and the orthographic projection of the through hole 260 on the first end face at least partially overlaps the orthographic projection of the flame-retardant member 40 on the first end face. When the explosion-proof valve is exploded, the lower plastic 26 may be melted and sprayed out, at which time the flame-retardant member 40 can isolate the cover plate body 22 from the electrode assembly 31 / 32 to avoid generating a pull arc to cause a fire explosion; when the explosion-proof valve is exploded, the lower plastic 26 may not be sprayed out, at which time the flame-retardant member 40 can also block high-temperature particles from falling from the through hole 260 to the electrode assembly 31 / 32.

[0053] Embodiments of the present application provide measures for improving safety after explosion of a secondary battery 100 in use, when the secondary battery 100 is subjected to a severe explosion due to a safety problem, the flame-retardant member 40 can avoid high-temperature objects or metal particles from falling on the electrode assembly 31 / 32 to cause further safety impact, the insulating flame-retardant member 40 can avoid a pull arc between the cover plate body 22 at a high potential and the electrode assembly 31 / 32 at the explosion-proof valve port 25 to cause a fire explosion; in addition, the risk existing at the explosion-proof valve 24 is improved by means of adhesive, which is more convenient than improving the design of the cover plate assembly 20 to achieve the purpose, and is easier to produce.

[0054] The above merely describes preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A secondary battery characterized by comprising: The secondary battery comprises: a housing having an opening; a cover plate assembly comprising a cover plate body and an explosion-proof valve disposed on the cover plate body, the cover plate body closing the opening and forming a containing cavity with the housing; an electrode assembly disposed in the containing cavity, comprising a first end face facing the cover plate assembly, a fireproofing member disposed on the first end face of the electrode assembly, the electrode assembly having a first tab extending from a portion of the first end face on which the fireproofing member is not disposed, a projection of the explosion-proof valve on the first end face at least partially overlapping a projection of the fireproofing member on the first end face.

2. The secondary battery according to claim 1, characterized by The projection of the explosion-proof valve on the first end face is located within the range of the projection of the fireproofing member on the first end face.

3. The secondary battery according to claim 1, wherein the electrode assembly has a first electrode sheet, a second electrode sheet, and a separator between the first electrode sheet and the second electrode sheet, the first tab being led out from the first electrode sheet, the first end face comprises a tab area and a blank area disposed along a thickness direction of the electrode assembly, the fireproofing member comprises a first portion and a second portion, the first portion is disposed in the blank area, the second portion is disposed in the tab area, the first tab extends from the tab area, and a width of the first portion along a width direction from the first tab to a second tab is greater than a width of the second portion.

4. The secondary battery according to claim 3, wherein the electrode assembly further has a second tab led out from the second electrode sheet, the second tab extends from the tab area, the first portion extends between edges of the first tab and the second tab opposite to each other along the width direction, and the second portion is disposed between the first tab and the second tab and extends to opposite sides of the electrode assembly along the thickness direction.

5. The secondary battery according to claim 4, characterized by The second portion is further disposed in the blank area at a portion between the first tab and the second tab along the width direction, and the first portion is superimposed on the second portion.

6. The secondary battery according to claim 1, characterized by The cover plate assembly further comprises: a lower plastic between the cover plate body and the electrode assembly, the lower plastic having a through hole, a projection of the explosion-proof valve on the first end face at least partially overlaps a projection of the through hole on the first end face, and the projection of the through hole on the first end face at least partially overlaps the projection of the fireproofing member on the first end face.

7. The secondary battery according to claim 4, characterized by The containing cavity contains a plurality of the electrode assemblies stacked, the fireproofing member is attached to the first end face of each of the electrode assemblies, and the second portion between two of the electrode assemblies disposed opposite to each other is misaligned.

8. The secondary battery according to claim 1, characterized by The fireproofing member is a heat-resistant adhesive tape or a mica sheet.

9. A battery pack characterized by comprising: The secondary battery according to any one of claims 1 to 8.

10. An electronic device, comprising: The battery pack according to claim 9.

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