CN109817853A - Secondary cell's top cap subassembly and secondary cell - Google Patents

Abstract

The present invention provides a top cover assembly of a secondary battery and a secondary battery. The top cover assembly of the secondary battery includes: a top cover plate with ventilation holes; a first electrode terminal, which is insulated from the top cover plate; a second electrode terminal, which is electrically connected to the top cover plate; a conductive member, which is electrically connected to the first electrode terminal and insulated from the top cover plate; a flip sheet attached to the top cover plate, and the flip sheet is configured to flip in response to an increase in the internal pressure of the secondary battery so as to electrically connect the flip sheet with the conductive member; and a sealing plug to seal the air The hole has a lower melting point than the top cover plate, and the sealing plug is configured to be deformed in response to an increase in the temperature of the environment in which the secondary battery is placed, so as to be released from the sealing state with the ventilation hole. It can solve the problem of overcharge of the secondary battery under normal temperature conditions, and at the same time, it can also discharge the gas generated inside the secondary battery in time in a high temperature environment, so as to avoid the short circuit between the positive electrode and the negative electrode of the secondary battery in a high temperature environment. Electrode assembly explosion and other accidents.

Description

Top cover assembly of secondary battery and secondary battery

technical field

The present invention relates to the technical field of energy storage devices, in particular to a top cover assembly of a secondary battery and a secondary battery.

Background technique

New energy vehicles are widely promoted in China and even in the world, but to completely replace fuel vehicles, there are still many things that need to be improved. For example, the mileage of the car is small, the cost of the battery pack is high, and the reliability of the battery pack needs to be further resolved. Based on the above problems, higher requirements are placed on the secondary battery, the core component of the electric vehicle, for example, the secondary battery needs to achieve higher energy density and lower cost.

A secondary battery differs from a primary battery in that it can be repeatedly charged and discharged, whereas the latter is not designed to be recharged. However, when the secondary battery is overcharged, heat and gas are rapidly generated, which may cause safety hazards such as fire or explosion of the secondary battery. Therefore, in order to prevent fire and explosion of the secondary battery due to overcharging, a short-circuit member may be provided on the top cover assembly of the secondary battery. The short-circuit member includes a connection plate connected to the negative electrode terminal, and a flip piece connected to the top cover plate to maintain a separated state from the connection plate, the flip piece being attached to the top cover plate and deformable in response to an increase in pressure inside the case to Turn over and contact the connection plate, since the top cover plate and the flip plate are connected to the positive electrode terminal, the positive and negative plates of the electrode assembly in the case can be short-circuited by the short-circuit part.

However, the above-mentioned components will reduce the ability of the secondary battery to cope with a high temperature environment. For example, when the above-mentioned components are used in a hot-box test, the probability of thermal runaway of the secondary battery is greatly increased. The specific reason is: in a high temperature environment, not only the internal air pressure in the secondary battery will increase with the decomposition of the electrolyte at high temperature, but also the internal resistance of the electrode assembly will also increase; The positive electrode sheet and the negative electrode sheet of the battery form an external short circuit, and the electrode assembly will generate more heat due to the increase of its internal resistance and the existence of the short circuit current, thereby increasing the risk of fire and explosion of the secondary battery. In other words, the existing external short-circuit member can only solve the problem of overcharge of the secondary battery under normal temperature conditions, but will increase the probability of thermal runaway in a high temperature environment.

Therefore, there is an urgent need for a new top cover assembly for a secondary battery and a secondary battery.

SUMMARY OF THE INVENTION

According to the embodiments of the present invention, a top cover assembly for a secondary battery and a secondary battery are provided, which can solve the problem of overcharging of the secondary battery under normal temperature conditions, and can also timely generate the internal generation of the secondary battery in a high temperature environment. The gas is discharged to avoid short circuit between the positive electrode and negative electrode of the secondary battery in a high temperature environment.

According to an aspect of the embodiments of the present invention, there is provided a top cover assembly for a secondary battery, including: a top cover plate with ventilation holes; a first electrode terminal, insulated from the top cover plate; and a second electrode terminal, with the top cover The plate is electrically connected; the conductive member is electrically connected to the first electrode terminal and is insulated from the top cover plate; a flip sheet is attached to the top cover plate, and the flip sheet is configured to flip in response to an increase in the internal pressure of the secondary battery so as to make the flip sheet is electrically connected to the conductive member; and a sealing plug that seals the vent hole and has a lower melting point than the top cover plate, the sealing plug is configured to deform in response to an increase in the temperature of the environment where the secondary battery is placed to release the seal with the vent hole state.

According to an aspect of the embodiments of the present invention, the melting point of the sealing plug is in the range of 80°C-200°C.

According to an aspect of the embodiments of the present invention, the sealing plug includes a body part, the body part covers the ventilation hole and abuts against a side surface of the top cover plate.

According to an aspect of the embodiments of the present invention, the sealing plug further includes an extension portion, the extension portion is connected to the body portion and extends into the ventilation hole.

According to an aspect of the embodiment of the present invention, the sealing plug further includes a limiting portion, the limiting portion is connected to the extension portion, and the limiting portion abuts and fits with a surface of the top cover plate on the side away from the body portion.

According to an aspect of the embodiment of the present invention, the top cover plate further includes an annular first sinking platform, the first sinking platform surrounds the perimeter of the ventilation hole and extends along the radial direction of the ventilation hole, and the body portion is accommodated in the first sinking platform.

According to an aspect of the embodiment of the present invention, the top cover assembly further includes a pressure block, the body portion is located between the pressure block and the top cover plate and is in contact with the pressure block and the top cover plate at the same time, the pressure block has a through hole, and the sealing plug is disengaged and ventilated After the hole is sealed, the through hole can communicate with the inside of the secondary battery.

According to an aspect of the embodiments of the present invention, the body part and the pressing block are both located on a side of the top cover plate away from the interior of the secondary battery, and the through holes are arranged opposite to the ventilation holes.

According to an aspect of the embodiment of the present invention, the top cover plate further includes an annular second sinker, the second sinker surrounds the perimeter of the first sinker and extends along the radial direction of the ventilation hole, and the pressing block is accommodated in the second sinker Taichung.

According to an aspect of the embodiment of the present invention, the body portion has an annular protrusion that contacts the pressing block, and the protrusion surrounds the through hole; or, the body portion has an annular protrusion that contacts the top cover plate, and the protrusion is Surround vents.

According to another aspect of the embodiments of the present invention, there is also provided a secondary battery, comprising: a case having an opening; an electrode assembly accommodated in the case, including a first pole piece, a second pole piece and a A separator between a pole piece and a second pole piece; and the above-mentioned top cover assembly, covering the opening of the casing, so as to enclose the electrode assembly in the casing.

To sum up, in the top cover assembly of the secondary battery and the secondary battery according to the embodiments of the present invention, the top cover plate is provided with a flip sheet that can be turned over in response to an increase in the pressure inside the secondary battery, so that the secondary battery can be overcharged at room temperature. At the same time, the electrode assembly inside the secondary battery can be short-circuited by flipping the sheet, so as to solve the problem of overcharge. At the same time, the top cover plate is provided with a vent hole and a sealing plug installed in the vent hole, and the sealing plug is configured to deform in response to an increase in the environment in which the secondary battery is located, and is released from the sealing state with the vent hole. Therefore, when the secondary battery is subjected to the hot box test, under the influence of the temperature in the hot box, the sealing plug can be deformed before the inversion sheet is turned over, thereby opening the ventilation holes and releasing the gas inside the secondary battery to the secondary battery external. Therefore, the top cover assembly of the secondary battery and the secondary battery according to the embodiments of the present invention can not only solve the overcharge problem of the secondary battery under normal temperature conditions, but also can avoid the increase of the internal resistance of the electrode assembly and the increase of the internal resistance during the hot box test. The existence of short-circuit current generates more heat, which leads to accidents such as fire and even explosion, which reduces the probability of thermal runaway of the secondary battery in a high temperature environment, thereby greatly improving the ability of the secondary battery to cope with high temperature environments.

Description of drawings

The present invention can be better understood from the following description of specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

Other features, objects and advantages of the present invention will become more apparent upon reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar features.

1 is a schematic cross-sectional structural diagram of a secondary battery cut along a longitudinal section line according to an embodiment of the present invention;

2 is a schematic diagram of an exploded structure of a top cover assembly according to an embodiment of the present invention;

Fig. 3 is the top-view structure schematic diagram of the top cover assembly in Fig. 2;

4 is a schematic cross-sectional structural diagram of the top cover assembly of FIG. 3 cut along the A-A section line;

Fig. 5 is the partial structure enlarged schematic diagram of A part in the top cover assembly of Fig. 4;

6 is an enlarged schematic view of a partial structure of part B in the top cover assembly of FIG. 4;

FIG. 7 is a schematic structural diagram of the ventilation hole of the top cover assembly in FIG. 6;

8 is a schematic cross-sectional structural diagram of the top cover assembly according to the second embodiment of the present invention after being cut along the longitudinal direction;

FIG. 9 is an enlarged schematic view of a partial structure of part C in the top cover assembly of FIG. 8;

FIG. 10 is a schematic structural diagram of the ventilation hole of the top cover assembly in FIG. 9;

11 is a schematic cross-sectional structural diagram of the top cover assembly according to the third embodiment of the present invention after being cut along the longitudinal direction;

FIG. 12 is an enlarged schematic view of a partial structure of part D in the top cover assembly of FIG. 11;

13 is a schematic cross-sectional structural diagram of the top cover assembly according to the fourth embodiment of the present invention after being cut along the longitudinal direction;

FIG. 14 is an enlarged schematic view of the partial structure of the E part in the top cover assembly of FIG. 13 .

Description of reference numbers:

1-secondary battery; 100-top cover assembly; 101-top cover assembly; 102-top cover assembly; 103-top cover assembly; 200-case; 300-electrode assembly; 400-terminal board;

10-top cover plate; 11-electrode lead-out hole; 12-through hole; 13-ventilation hole; 131-first sinking platform; 132-second sinking platform; 14-explosion-proof valve assembly;

20-terminal assembly; 21-pole; 211-extension; 22-electrical connection plate; 221-through hole; 222-connection part; 223-contact part; 242-accommodating space; 243-through hole; 244-through hole; 25-flip sheet; 251-curved part; 252-circumferential edge part; 253-protruding part;

30-terminal assembly; 31-pole; 32-electrical connection plate; 33-seal; 34-isolation;

41-the first insulating part; 42-the second insulating part;

60-sealing plug; 61-body part; 62-extension part; 63-limiting part; 64-protrusion;

70-Press block; 71-Through hole.

Detailed ways

Features and exemplary embodiments of various aspects of the invention are described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is only intended to provide a better understanding of the present invention by illustrating examples of the invention. In the drawings and the following description, at least some well-known structures and techniques are not shown in order to avoid unnecessarily obscuring the present invention; and, the dimensions of some structures may be exaggerated for clarity. The same reference numerals in the drawings denote the same or similar structures, and thus their detailed descriptions will be omitted. Furthermore, the features, structures or characteristics described below may be combined in any suitable manner in one or more embodiments.

The orientation words appearing in the following description are all directions shown in the drawings, and do not limit the specific structure of the top cover assembly of the present invention. In the description of the present invention, it should also be noted that, unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it may be a fixed connection or a connectable connection. Detachable connection, or integral connection; it can be directly connected or indirectly connected. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific conditions.

The top cover assembly of the secondary battery provided by the embodiment of the present invention can cover the opening of the casing 200 of the secondary battery, so as to seal the electrode assembly and the electrolyte used for electrochemical reaction in the casing 200, and realize the electrode assembly Electrical connection of components to conductive components external to housing 200 . In addition, the top cover assembly of the embodiment of the present invention can reduce the thermal runaway probability of the secondary battery in a high temperature environment, improve the ability of the power battery to cope with the high temperature environment, and thus can ensure the safety and reliability of the secondary battery.

In order to better understand the present invention, the top cover assembly of the secondary battery and the secondary battery according to the embodiments of the present invention will be described below with reference to FIGS. 1 to 14 .

1 is a schematic cross-sectional structural diagram of a secondary battery 1 cut along a longitudinal section line according to an embodiment of the present invention. As shown in FIG. 1 , the secondary battery 1 generally includes a cap assembly 100 , a case 200 , and an electrode assembly 300 and a terminal plate 400 inside the case 200 .

According to one embodiment of the present invention, the case 200 may be made of a metal material, such as aluminum, aluminum alloy, or nickel-plated steel, and in this embodiment, the case 200 is formed in a rectangular box shape and has an opening to The accommodating space therein is communicated through the opening.

The electrode assembly 300 may be formed by stacking or winding a first pole piece, a second pole piece, and a separator, wherein the separator is an insulator between the first pole piece and the second pole piece. In this embodiment, the first pole piece is exemplarily used as a negative electrode piece, and the second pole piece is used as a positive electrode piece for description. Similarly, in other embodiments, the first pole piece may also be a positive pole piece, and the second pole piece may be a negative pole piece. In addition, the positive electrode sheet active material is coated on the coated area of the positive electrode sheet, and the negative electrode sheet active material is coated on the coated area of the negative electrode sheet. The uncoated part extending from the coating area of the first pole piece is used as the pole lug, namely the first pole lug; the uncoated part extending from the coating area of the second pole piece is used as the pole lug, namely the first pole lug Diodes.

FIG. 2 is a schematic diagram of an exploded structure of the top cover assembly 100 according to an embodiment of the present invention; FIG. 3 is a schematic top view of the structure of the top cover assembly 100 in FIG. 2 . Referring to FIG. 2 and FIG. 3 together, the top cover assembly 100 is used for sealing the casing 200 , and can seal the electrode assembly 300 in the casing 200 . According to one embodiment of the present invention, the top cover assembly 100 generally includes a top cover plate 10 , a terminal assembly 20 , a terminal assembly 30 and a lower insulating structure.

The top cover 10 is in the shape of a thin plate, and has a size and shape matching the opening of the casing 200 so as to be able to be connected at the opening of the casing 200 . The top cover plate 10 is made of a metal material. Exemplarily, the top cover plate 10 can be selected from the same metal material as that of the casing 200 , such as aluminum, steel and other materials. In this embodiment, the top cover plate 10 is provided with two electrode lead-out holes 11 , through holes 12 , ventilation holes 13 and an explosion-proof valve assembly 14 .

The explosion-proof valve assembly 14 can adopt the existing structure (for example, the explosion-proof disc is provided), and the explosion-proof valve assembly 14 is disposed in the approximate middle position of the top cover plate 10. When the gas is generated due to overcharging, overdischarging or overheating of the battery, the secondary battery may be damaged. When the internal pressure of 1 is too large, the explosion-proof disc in the explosion-proof valve assembly 14 can be broken so that the gas formed inside the secondary battery 1 can be discharged to the outside, thereby preventing the secondary battery 1 from exploding.

4 is a schematic cross-sectional structural diagram of the top cover assembly 100 of FIG. 3 cut along the A-A section line; FIG. 5 is an enlarged schematic partial structure of part A of the top cover assembly 100 of FIG. 4 . Referring to FIGS. 2 to 5 together, according to an exemplary embodiment of the present invention, the top cover plate 10 is provided with two electrode lead-out holes 11 , which are respectively used for the electrode terminals in the terminal assembly 20 and the terminal assembly 30 to connect to each other. The electric energy in the electrode assembly 300 inside the case 200 is extracted to the outside of the secondary battery 1 .

In one exemplary embodiment, terminal assembly 20 generally includes a first electrode terminal, seal 23 , and spacer 24 ; similarly, terminal assembly 30 generally includes a second electrode terminal, seal 33 , and spacer 34 . In the following, only the structure of the terminal assembly 20 itself and the installation form of the terminal assembly 20 on the top cover plate 10 are taken as an example for illustrative description. In addition, unless otherwise specified, the terminal assembly 20 is exemplarily described as a negative terminal assembly, and the terminal assembly 30 is a positive terminal assembly.

According to an embodiment of the present invention, the first electrode terminal generally includes three parts: an external wiring part for realizing electrical connection with a component outside the secondary battery 1 (eg, a bus bar), and a part for realizing fixing with the top cover plate 10 The connecting portion for connection and the inner wiring portion for making electrical connection inside the battery (ie, the secondary battery 1 ) with the first tab of the electrode assembly 300 inside the case 200 . In this embodiment, specifically, the first electrode terminal includes a pole 21 and an electrical connection plate 22, wherein the pole 21 includes a pole body as a connection part fixedly connected with the top cover plate 10 and a pole body as a connection with the first pole The ear realizes the extension 211 of the inner wiring part for electrical connection, and the electrical connection plate 22 serves as the outer wiring part for connecting with the bus bar.

Exemplarily, in this embodiment, the pole body can be made of copper or copper alloy and has a cylindrical structure, the diameter of the pole body is adapted to the diameter of the electrode lead-out hole 11, and the extension 211 is compatible with the pole pole. The body is connected to the board body. Exemplarily, the pole body and the extension part 211 may be provided in an integral molding manner, and the area of the cross section of the extension part 211 is larger than the area of the cross section of the pole body.

Exemplarily, in this embodiment, the electrical connection board 22 includes a connection portion 222 and a contact portion 223. Of course, it is preferable that the connection portion 222 and the contact portion 223 are integrally formed to form the electrical connection board 22, and the connection portion 222 and The contact portion 223 has a plate shape and is configured in a stepped structure, that is, the thickness of the connection portion 222 is larger than that of the contact portion 223 . A through hole 221 is provided at a substantially central position of the connecting portion 222 , and the diameter of the through hole 221 is adapted to the diameter of the pole body of the pole 21 .

When the first electrode terminal is mounted on the top cover plate 10 , the electrical connection plate 22 needs to be fixed on the side of the top cover plate 10 away from the interior of the secondary battery 1 , and the electrode post 21 protrudes from the interior of the secondary battery 1 and is connected to the electrical connection plate 10 . The connecting plate 22 is connected. According to one embodiment of the present invention, the outer peripheral surface of the electrical connection plate 22 is at least partially surrounded by the spacer 24 to insulatively separate the electrical connection plate 22 from the top cover plate 10 by the spacer 24 .

The spacer 24 is a hard plastic part, and can be made of a high temperature resistant insulating plastic material, for example, the spacer 24 can be made of one of polyphenylene sulfide PPS, perfluoroalkoxy resin PEA or polypropylene PP or multiple materials. Specifically, the main body of the spacer 24 is in the shape of a plate, and an annular flange is provided around the edge of the main body to form a sinking portion 241 on one side of the main body, and the spacer 24 corresponds to the connection portion 222 and The contact portion 223 has a first isolation area and a second isolation area, respectively, and the second isolation area is provided with a baffle plate, and the baffle plate is connected to the top surface of the annular flange, so as to pass the baffle plate and the sink portion 241 at the isolation member. A receiving space 242 is formed on one side of the second isolation area of 24 . The main body of the spacer 24 has a through hole 243 located in the first isolation region and a through hole 244 located in the second isolation region, and the position of the through hole 243 corresponds to the electrode lead-out hole 11 , and the position of the through hole 244 corresponds to the position of the through hole 12 Corresponding.

After the electrical connection plate 22 is fixed to the spacer 24, the connection part 222 is located in the first isolation area of the spacer 24, and the contact part 223 is located in the second isolation area of the spacer 24, that is to say, the top surface of the connection part 222 passes through the spacer 24. The open portion of the spacer 24 is exposed to the outside, and the contact portion 223 is integrally embedded in the accommodating space 242 . The electrical connection plate 22 and the spacer 24 are fixed to each other and placed together on the side of the top cover 10 away from the interior of the secondary battery 1 , so that the main portion of the spacer 24 is sandwiched between the electrical connection plate 22 and the top cover 10 . And the through hole 221 of the electrical connection plate 22, the through hole 243 of the spacer 24 and the electrode lead-out hole 11 are aligned, and the through hole 244 of the spacer 24 and the through hole 12 of the top cover plate 10 are aligned with each other, so that the contact part 223 can be exposed inside the casing 200 through the through hole 244 and the through hole 12 . Of course, the spacer 24 can be formed between the electrical connection board 22 and the top cover plate 10 by integral injection molding; or the spacer 24 can be produced separately and assembled with the electrical connection board 22 .

Further, the pole body of the pole 21 protrudes from the side of the top cover 10 facing the secondary battery 1 through the electrode lead-out hole 11 toward the outside of the secondary battery 1 , and the extension 211 can abut against the top cover 10 It faces the side of the secondary battery 1 , so as to limit the position of the pole 21 . After the pole body protrudes from the top cover plate 10, it further extends into the through hole 221 of the electrical connecting plate 22, so as to riveted the pole 21 and the electrical connecting plate 22, so as to fix the first electrode terminal on the top cover plate. 10.

Of course, the structure of the terminal assembly 30 is similar to that of the terminal assembly 20. The second electrode terminal of the terminal assembly 30 also includes a pole 31 and an electrical connection plate 32 connected between the pole 31 and the bus bar of the battery module. The area of the electrical connection plate 32 in the second electrode terminal is small, so the size of the spacer 34 sandwiched between the electrical connection plate 32 and the top cover plate 10 is also small, and in this embodiment, the terminal assembly 30 The spacer 34 is not an insulating material, so the pole 31 and the top cover plate 10 are always in an electrical connection state.

In addition, in order to ensure the tightness of the electrode lead-out hole 11 , the sealing member 23 is provided between the electrode post 21 and the top cover plate 10 . The sealing member 23 includes an axially extending portion and a radially extending portion, wherein the axially extending portion is sandwiched between the top cover plate 10 and the pole body, and the radially extending portion is sandwiched between the top cover plate 10 and the extension portion 211 Therefore, the sealing member 23 is in close contact with the top cover plate 10 and the pole 21 respectively, thereby ensuring the airtightness of the secondary battery 1 .

The terminal plate 400 is located inside the casing 200, and the secondary battery 1 has two terminal plates 400, the two terminal plates 400 are respectively arranged corresponding to the first pole piece and the second pole piece, and are connected to the first electrode terminal and the first pole respectively. between the pieces and between the second electrode terminal and the second pole piece. That is, the two wiring boards 400 are respectively used to realize the electrical connection between the first electrode terminal and the first tab, and the electrical connection between the second electrode terminal and the second tab.

In addition, in order to maintain the insulating state between the top cover plate 10 and the electrode assembly 300 and the wiring board 400 inside the casing 200, the lower insulating structure is usually made of plastic material. According to an exemplary embodiment of the present invention, the lower insulating structure includes a first insulating part 41 and a second insulating part 42 , wherein the first insulating part 41 is attached to a side of the top cover plate 10 facing the inside of the casing 200 , and Corresponds to the terminal assembly 20 . The second insulating portion 42 is attached to the side of the top cover 10 facing the inside of the housing 200 and corresponds to the terminal assembly 30 . In addition, the first insulating portion 41 and the second insulating portion 42 respectively have through holes corresponding to the electrode extraction holes 11 on both sides, so as to realize the extraction of electrical energy from the electrode assembly 300 .

In order to avoid fire and explosion caused by repeated charging and discharging of the secondary battery 1 when the pressure rises, a flip sheet 25 is also provided between the first electrode terminal and the second electrode terminal, and the flip sheet 25 is in the casing of the secondary battery 1 . When the pressure inside 200 exceeds a predetermined value (ie, exceeds the reference pressure), it is turned over and electrically connected to the electrical connection plate 22 so as to short-circuit the first pole piece and the second pole piece of the secondary battery 1 in time.

Specifically, the flip sheet 25 is attached to the top cover 10 , and the flip sheet 25 has a film-like curved portion 251 , a circumferential edge portion 252 , and a protruding portion 253 , wherein the curved portion 251 is configured to protrude toward the inner space of the housing 200 Circumferential arc; a circumferential edge portion 252 is formed on the outer side of the curved portion 251. The through hole 12 opened on the top cover plate 10 has a recessed table structure, whereby the peripheral edge portion 252 of the flip sheet 25 can be welded and connected to the recessed table of the through hole 12, thereby electrically connecting the flip sheet 25 to the top cover plate 10. ; The protruding portion 253 protrudes from the approximately central position of the curved portion 251 to the outside of the housing 200 .

Therefore, the flip sheet 25 connected at the through hole 12 can be opposed to the contact portion 223 of the electrical connection plate 22 via the through hole 244 of the spacer 24 and maintain a separated state. Meanwhile, the surface of the flip sheet 25 facing away from the electrical connection plate 22 is exposed inside the housing 200 , so that the gas generated inside the housing 200 can quickly flow to the lower surface of the flip sheet 25 . And the flip sheet 25 is configured such that when the pressure inside the case 200 is increased, the bent portion 251 of the flip sheet 25 can be flipped and changed to be bent in a direction toward the outside of the case 200 so as to align with the through hole 244 of the spacer 24 . The exposed contact portion 223 is in contact and electrically connected. Since the flip sheet 25 can be electrically connected to the second electrode terminal through the top cap plate 10, the material of the flip sheet 25 and the material of the top cap plate 10 have the same base metal.

Thus, when the pressure inside the case 200 of the secondary battery 1 rises (eg, exceeds a predetermined pressure threshold), the flip sheet 25 can be deformed, that is, the bent portion 251 of the flip sheet 25 is oriented away from the inner space of the case 200 . It is turned over so that the protruding portion 253 thereon forms an electrical connection with the electrical connection plate 22, so that the first electrode terminal (ie the pole 21 and the electrical connection plate 22), the flip sheet 25, the top cover plate 10 and the second electrode terminal (ie, the pole 31 and the electrical connection plate 32) are turned on in sequence, that is, the first pole piece and the second pole piece are short-circuited, and the electrical connection plate 22 is connected to the flip piece 25 to maintain this short-circuit state. When a short circuit occurs, a large current is instantaneously (or substantially instantaneously) generated between the first pole piece and the second pole piece, so the electrode assembly 300 is discharged.

Therefore, in the present embodiment, the electrical connection plate 22 is used as a conductive member, and when the internal pressure of the secondary battery 1 exceeds a predetermined threshold, the flip sheet 25 after being flipped is electrically connected to the pole 21, but the embodiment of the present invention is not limited to this, In other embodiments, other conductive members can also be provided on the top cover plate 10 , and the conductive members are electrically connected to the first electrode terminals and insulated from the top cover plate, so as to realize the connection between the flip sheet 25 and the pole 21 . electrical connection.

When the secondary battery 1 is subjected to a hot box test (for example, the temperature is kept at 130° C. for a certain period of time), due to the high external temperature of the secondary battery 1, the internal chemical reaction of the secondary battery 1 is violent and a large amount of gas will be produced. When the air pressure is increased enough to turn the flip sheet 25 over, the risk of fire and explosion of the secondary battery 1 is increased. In the embodiment of the present invention, the top cover assembly 100 includes a vent hole 13 provided on the top cover plate 10 , and a sealing plug 60 installed at the vent hole 13 , the vent hole 13 is sealed by the sealing plug 60 , and the sealing plug 60 is It is configured to deform in response to an increase in the ambient temperature of the secondary battery 1, and to disengage from the sealed state with the vent hole 13 before the flip sheet 25 is flipped over, so that the gas in the case 200 can be discharged through the vent hole 13, thereby reducing the secondary battery. Risk of thermal runaway of battery 1.

FIG. 6 is an enlarged schematic view of the partial structure of the part B of the top cover assembly 100 in FIG. 4 ; FIG. 7 is a schematic view of the structure at the ventilation hole 13 of the top cover assembly 100 in FIG. 6 . As shown in FIG. 2 , FIG. 4 , FIG. 6 and FIG. 7 , according to an embodiment of the present invention, the sealing plug 60 includes three parts, and the sealing plug 60 is respectively engaged with the two side surfaces of the top cover plate 10 at the same time in a limited position and fixed. The vent hole 13 is located and sealed to ensure the normal use of the secondary battery 1 .

Specifically, the ventilation hole 13 provided on the top cover plate 10 is close to the side of the terminal assembly 20, but the setting position of the ventilation hole 13 is not limited in the embodiment of the present invention. In other embodiments, the ventilation hole 13 is also Other locations on the roof panel 10 may be provided. Specifically, in this embodiment, the top cover 10 further includes a first sinking table 131 . The first sinking platform 131 is annular, is formed on the side of the top cover 10 away from the interior of the secondary battery 1 , and surrounds the perimeter of the ventilation hole 13 . An annular recess formed by extending radially away from the ventilation hole 13 . Of course, it should be noted that the opening depth and extension area of the first sink 131 need not affect the structural strength of the top cover 10 .

Specifically, in this embodiment, the sealing plug 60 installed at the vent hole 13 has a lower melting point than the top cover plate 10 . For example, the material of the sealing plug 60 may be PP (polypropylene, polypropylene), PE (polyethylene, polyethylene) ethylene) etc. Illustratively, the melting point of the sealing plug 60 may range from 80°C to 200°C. When the ambient temperature exceeds the melting point of the sealing plug 60, the sealing plug 60 will be deformed, that is, the phenomenon of melting or softening will occur. At this time, the sealing plug 60 will be separated from the sealing state with the ventilation hole 13, so that the ventilation hole 13 will be opened. , the gas inside the secondary battery 1 can be discharged to the outside through the ventilation holes 13 .

In this embodiment, the sealing plug 60 includes: a main body part 61 , an extension part 62 and a limiting part 63 . The body portion 61 and the limiting portion 63 are both circular sheet-like bodies, and the extension portion 62 is a cylinder matched with the ventilation hole 13. The extension portion 62 is connected between the body portion 61 and the limiting portion 63, so that the body The portion 61 and the stopper portion 63 are parallel to each other. When the sealing plug 60 is installed at the vent hole 13 , the body portion 61 is located in the first sink 131 and covers the vent hole 13 . It is located on the side of the top cover plate 10 facing the inside of the secondary battery 1 , and abuts against and cooperates with the surface of the top cover plate 10 to limit the position of the body portion 61 and the extension portion 62 . In this way, the body part 61 and the limiting part 63 are in close contact with the two side surfaces of the top cover plate 10 respectively, so that the sealing plug 60 can be directly and stably fixed at the ventilation hole 13 through its own structure.

Of course, the area of the body portion 61 and the limiting portion 63 may be the same or different, but preferably the size of the body portion 61 is adapted to the size of the first sink 131 so as to pass the peripheral edge of the body portion 61 and the first sink 131 The tight fit ensures the airtightness of the secondary battery 1 . Moreover, when the top cover plate 10 has a sufficient thickness, a corresponding sink structure can also be provided on the side of the top cover plate 10 facing the inside of the secondary battery 1 corresponding to the limiting portion 63 . By arranging the first sink 131 , the space occupied by the sealing plug 60 in the height direction can be reduced, thereby ensuring the energy density of the secondary battery 1 .

In addition, the body portion 61 and the limiting portion 63 are not limited to the circular sheet in the above embodiment, and in other embodiments, the body portion 61 and the limiting portion 63 may also be other shapes, such as square, triangle, etc. Of course, it is preferable to set the size of the first sinking table 131 to suit the size of the body portion 61 . Moreover, the embodiment of the present invention does not limit the installation method of the sealing plug 60. For example, the sealing plug 60 can be directly installed on the top cover plate 10 by integral injection molding. And the limiting portion 63 is sequentially installed on the top cover plate 10 by means of thermal fusion.

Since it takes a certain amount of time for the internal air pressure of the secondary battery 1 to increase during the hot box test, the flip sheet 25 does not turn over as soon as the secondary battery 1 is placed in the hot box, but once the secondary battery 1 enters the hot box , the heat in the hot box is immediately conducted to the sealing plug 60 installed on the top cover plate 10 , and the sealing plug 60 is deformed in response to an increase in the ambient temperature. That is, when the ambient temperature is close to the melting point of the sealing plug 60, the sealing plug 60 will soften or melt, thereby causing it to break away from the sealing state with the ventilation hole 13, so that the ventilation hole 13 is opened. At this time, the gas generated inside the secondary battery 1 It will be discharged to the outside through the opened ventilation holes 13 . Therefore, when the secondary battery 1 is subjected to the hot box test, the sealing plug 60 installed on the top cover 10 will be deformed first under the influence of the temperature of the hot box, thereby preventing the flip sheet 25 from turning over after the secondary battery 1 enters the hot box. , causing the internal resistance of the electrode assembly 300 to increase, thereby causing the secondary battery 1 to catch fire or even explode. Therefore, the top cover assembly 100 of the embodiment of the present invention can reduce the thermal runaway probability of the secondary battery 1 in a high temperature environment, and improve the ability of the secondary battery 1 to cope with a high temperature environment.

FIG. 8 is a schematic view of the top cover assembly 101 according to the second embodiment of the present invention after being cut along the longitudinal direction; FIG. 9 is an enlarged schematic partial structure of the C part in the top cover assembly 101 of FIG. 8 ; Schematic diagram of the structure of the ventilation hole 13. For ease of understanding, in this embodiment, the same reference numerals are used for the same components as those in the first embodiment, and the structures that have been described in detail will not be repeated. As shown in FIG. 8 to FIG. 10 , according to another embodiment of the present invention, similarly, the sealing plug 60 includes three parts, and the sealing plug 60 is simultaneously limited and matched with the two side surfaces of the top cover plate 10 , and is fixed to the ventilation The ventilation hole 13 is sealed at the hole 13 to ensure the normal use of the secondary battery 1 , and the material of the sealing plug 60 in this embodiment is the same as that of the second embodiment above. The difference is that the top cover assembly 101 further includes a pressing block 70 , and the pressing block 70 can press the sealing plug 60 from the outside to the inside of the secondary battery 1 , so as to further fix the sealing plug 60 .

Specifically, in this embodiment, the top cover 10 includes a second sink 132 in addition to the first sink 131 . The second sink 132 is annular, and is also formed on the side of the top cover plate 10 away from the interior of the secondary battery 1, and surrounds the outer circumference of the first sink 131, that is to say, the second sink 132 is formed by the first sink 132. The outer circumference of the platform 131 is extended in a direction away from the ventilation hole 13 to form an annular recess, so that the first sinking platform 131 and the second sinking platform 132 form a stepped structure. Of course, it should be noted that the opening depth and expansion area of the first sinking platform 131 and the second sinking platform 132 need not affect the structural strength of the top cover plate 10 .

In the present embodiment, the pressing block 70 is also a circular sheet-like body, and a through hole 71 is provided at a substantially middle position of the pressing block 70 . After the sealing plug 60 is installed at the vent hole 13 , the main body 61 is located in the first sink 131 , and the pressing block 70 is located in the second sink 132 , that is to say, the main body 61 is located in the pressing block 70 and the top cover 10 . It is in contact with the pressing block 70 and the top cover plate 10 between and at the same time. And the position of the through hole 71 is aligned with the position of the ventilation hole 13 of the top cover plate 10 , so that after the sealing plug 60 is deformed, the gas inside the secondary battery 1 is discharged through the ventilation hole 13 and the through hole 71 .

According to an optional embodiment of the present invention, in order to further ensure the airtightness of the secondary battery 1 , the sealing plug 60 further has an annular protrusion 64 . Specifically, in this embodiment, the body portion 61 is provided with protrusions 64 around the through holes 71 on the surfaces facing the pressing block 70 and the top cover plate 10 respectively, so that the body portion 61 is in contact with the pressing block 70 and the top cover plate 10 . When in contact, annular sealing lines can be formed between the body part 61 and the pressing block 70 and between the body part 61 and the top cover plate 10 respectively through the protrusions 64, so that the air tightness of the secondary battery 1 can be further ensured. The phenomenon of gas leakage and liquid leakage of the secondary battery 1 under normal use conditions is avoided, so that the use reliability of the secondary battery 1 can be improved.

Therefore, in the present embodiment, when the secondary battery 1 is subjected to a high temperature test, when the ambient temperature increases or even reaches the melting point of the sealing plug 60 , the sealing plug 60 is deformed (ie, melted or softened) to break away from the sealing with the vent hole 13 In this state, the vent holes 13 are further opened, so that the gas in the secondary battery 1 can be quickly discharged. At the same time, by adding a pressing block 70 on the side of the top cover plate 10 away from the secondary battery 1 to further fix the sealing plug 60, the sealing plug 60 can also be prevented from being detached from the ventilation hole 13 during use. The body portion 61 exerts pressure to make the body portion 61 closely adhere to the top cover plate 10 , thereby improving the overall airtightness and safety of the secondary battery 1 .

In addition, in the second embodiment, the through hole 71 of the pressing block 70 is opposite to the ventilation hole 13 , but the embodiment of the present invention is not limited to this. In other embodiments, the through hole 71 may also be provided in the pressing block 70 . At other positions, as long as the sealing plug 60 is deformed, the through hole 71 can communicate with the interior of the secondary battery 1 to allow the gas inside the secondary battery 1 to be discharged through the vent hole 13 and the through hole 71 . In addition, in other embodiments, the pressing block 70 may also be located on the side of the top cover plate 10 facing the inside of the secondary battery 1 , in this case, the limiting portion 63 is located between the top cover plate 10 and the pressing block 70 and at the same time In contact with the top cover plate 10 and the pressing block 70 , the purpose of pressing the sealing plug 60 can also be achieved by the pressing block 70 .

11 is a schematic cross-sectional structural diagram of the top cover assembly 102 according to the third embodiment of the present invention after being cut along the longitudinal direction; FIG. For ease of understanding, in this embodiment, the same reference numerals are used for the same components as those in the second embodiment, and the structures that have been described in detail will not be repeated. As shown in FIG. 11 and FIG. 12 , the material of the sealing plug 60 in this embodiment is the same as that of the above-mentioned second embodiment, the difference is that the sealing plug 60 includes two parts, and the sealing plug 60 and the top cover plate 10 are made of the same material. One side limit fit is fixed at the vent hole 13 and seals the vent hole 13 to ensure the normal use of the secondary battery 1 . Of course, the top cover assembly 102 also includes a pressing block 70 through which the sealing plug 60 is pressed from the outside to the inside of the secondary battery 1 .

The top cover plate 10 also includes the ventilation holes 13 , the first sinking platform 131 and the second sinking platform 132 . The sealing plug 60 includes a body part 61 and an extension part 62 connected to each other, wherein the body part 61 is located in the first sink 131 , the extension part 62 extends into the ventilation hole 13 , and the pressing block 70 is located in the second sink 132 . Then the body portion 61 is also located between the pressing block 70 and the top cover plate 10 and is in contact with the pressing block 70 and the top cover plate 10 at the same time, so the sealing plug 60 of the second embodiment can also be installed without the limiting portion 63 at the vent hole 13 and seal the vent hole 13 . That is, when the secondary battery 1 is subjected to a high temperature test, when the ambient temperature is close to the melting point of the sealing plug 60 , the sealing plug 60 will deform (ie, melt or soften) to break away from the sealing state with the vent hole 13 , thereby opening the vent hole 13 , so that the gas in the secondary battery 1 is quickly discharged.

In addition, the sealing plug 60 in this embodiment is fixed to the top cover plate 10 through the pressing block 70, but the embodiment of the present invention is not limited to this. In other embodiments, only the sealing of the body portion 61 and the extension portion 62 is included. The plug 60 can also be fixed to the top cover plate 10 by other fixing methods.

13 is a schematic cross-sectional structural diagram of the top cover assembly 103 according to the fourth embodiment of the present invention after being cut along the longitudinal direction; FIG. For ease of understanding, in this embodiment, the same reference numerals are used for the same components as those in the third embodiment, and the structures that have been described in detail will not be repeated. As shown in FIG. 8 to FIG. 10 , this embodiment is similar to the above-mentioned third embodiment, the difference is that the sealing plug 60 only includes a main body portion 61 to limit the position between the main body portion 61 and one side surface of the top cover plate 10 Matching, fixed at the ventilation hole 13 and sealing the ventilation hole 13 . Of course, the top cover assembly 102 also includes a pressing block 70 through which the sealing plug 60 is pressed from the outside to the inside of the secondary battery 1 .

The top cover plate 10 also includes the ventilation holes 13 , the first sinking platform 131 and the second sinking platform 132 . The body portion 61 of the sealing plug 60 is located in the first sink 131 , and the pressing block 70 is located in the second sink 132 . Then the body portion 61 is also located between the pressing block 70 and the top cover plate 10 and is in contact with the pressing block 70 and the top cover plate 10 at the same time. Therefore, on the basis of the sealing plug 60 of the third embodiment, the extension portion 62 can also be removed. The ventilation hole 13 is located and the ventilation hole 13 is sealed. That is, when the secondary battery 1 is subjected to a high temperature test, when the ambient temperature is close to the melting point of the sealing plug 60 , the sealing plug 60 will deform (ie, melt or soften) to break away from the sealing state with the vent hole 13 , thereby opening the vent hole 13 , so that the gas in the secondary battery 1 is quickly discharged. Likewise, the sealing plug 60 in this embodiment can also be connected to the top cover plate 10 in other fixing manners.

In addition, in the above three embodiments, the ventilation holes 13 are all disposed on the top cover plate 10 , but the embodiments of the present invention are not limited thereto. In other embodiments, the ventilation holes 13 can also be provided in other parts of the secondary battery 1 , for example, the ventilation holes 13 can also be provided on the casing 200 of the secondary battery 1 , as long as the ventilation holes 13 can supply the casing The gas inside the body 200 may be exhausted. In addition, in the third embodiment and the fourth embodiment, the sealing plug 60 is installed to the ventilation hole 13 of the top cover plate 10 from the side of the top cover plate 10 away from the inside of the secondary battery 1, but the embodiments of the present invention do not Not limited to this, in other embodiments, the sealing plug 60 may also be installed on the top cover plate 10 from the inner side of the secondary battery 1 .

According to another embodiment of the present invention, a secondary battery 1 is also provided, including: a top cover assembly 100 , a case 200 and an electrode assembly 300 . The casing 200 has an opening; the electrode assembly 300 is accommodated in the casing 200 and includes a first pole piece, a second pole piece and a separator disposed between the first pole piece and the second pole piece; the top cover assembly 100 covers The opening of the case 200 to enclose the electrode assembly 300 in the case 200 . Since the structure and advantages of the secondary battery 1 have been described in the above embodiments, they will not be repeated here.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. Accordingly, the present embodiments are to be considered in all respects as illustrative and not restrictive, and the scope of the present invention is defined by the appended claims rather than the foregoing description, and falls within the meaning and equivalents of the claims. All changes within the scope are thus included in the scope of the invention. Also, different technical features appearing in different embodiments can be combined to achieve beneficial effects. Those skilled in the art should be able to understand and implement other variant embodiments of the disclosed embodiments on the basis of studying the drawings, the description and the claims.

Claims (11)

1. A cap assembly of a secondary battery, comprising:

a top cover plate having an air hole;

a first electrode terminal insulated from the top cap plate;

a second electrode terminal electrically connected to the top cap plate;

a conductive member electrically connected to the first electrode terminal and insulated from the top cap plate;

an inversion sheet attached to the top cap plate and configured to invert in response to an increase in internal pressure of the secondary battery to electrically connect the inversion sheet with the conductive member; and

a sealing plug sealing the vent hole and having a lower melting point than the top cap plate, the sealing plug being configured to be deformed in response to an increase in an ambient temperature in which the secondary battery is located, to be out of a sealed state with the vent hole.

2. The cap assembly of claim 1, wherein the sealing plug has a melting point in the range of 80 ℃ to 200 ℃.

3. The header assembly of claim 1, wherein the sealing plug includes a body portion that covers the vent and that abuttingly engages a side surface of the header plate.

4. The header assembly of claim 3, wherein the sealing plug further comprises an extension connected to the body portion and extending into the vent.

5. The header assembly of claim 4, wherein the sealing plug further comprises a stopper portion, the stopper portion is connected to the extension portion, and the stopper portion is in abutting engagement with a surface of the header plate on a side away from the body portion.

6. The header assembly of any one of claims 3 to 5, wherein the header plate further comprises an annular first counter sink surrounding a perimeter of the vent and extending radially of the vent, and the body portion is received in the first counter sink.

7. The cap assembly of claim 6, further comprising a pressing block, wherein the body portion is located between and in contact with the pressing block and the top cap plate, and wherein the pressing block has a through hole that can communicate with the inside of the secondary battery after the sealing plug is removed from the sealing state with the vent hole.

8. The cap assembly according to claim 7, wherein the body portion and the pressing block are located on a side of the cap plate away from the inside of the secondary battery, and the through hole is disposed opposite to the vent hole.

9. The lid assembly of claim 7, wherein the top cover plate further comprises an annular second counter sink extending around a perimeter of the first counter sink and radially of the vent, and the press block is received in the second counter sink.

10. The lid assembly of claim 7, wherein the body portion has an annular projection in contact with the pressure piece, and the projection surrounds the through hole; or,

the body part is provided with an annular bulge which is in contact with the top cover plate, and the bulge surrounds the vent hole.

11. A secondary battery, characterized by comprising:

a housing having an opening;

an electrode assembly accommodated in the case, including a first pole piece, a second pole piece, and a separator disposed between the first pole piece and the second pole piece; and

the cap assembly of any one of claims 1 to 10, covering an opening of the case to enclose the electrode assembly in the case.