WO2018107436A1

WO2018107436A1 - Battery top cap assembly and secondary battery

Info

Publication number: WO2018107436A1
Application number: PCT/CN2016/110117
Authority: WO
Inventors: 朱凌波; 李全坤; 郑志民; 迟庆魁; 史平
Original assignee: 宁德时代新能源科技股份有限公司
Priority date: 2016-12-15
Filing date: 2016-12-15
Publication date: 2018-06-21

Abstract

Provided are a battery top cap assembly and a secondary battery. The battery top cap assembly comprises a first pole assembly (20), a second pole assembly (21), a top cap piece (22), and a voltage sensing component (30) having unilateral conductivity. The second pole assembly is electrically connected to the top cap piece, and the voltage sensing component is located between the first pole assembly and the top cap piece. In a normal operating state, the first pole assembly and the top cap piece apply a reverse voltage to the voltage sensing component, and when a voltage of a battery exceeds a reference voltage, the voltage sensing component undergoes reverse break down. A trigger condition of the voltage sensing component is a voltage, and the voltage on the voltage sensing component undergoes rapid change only when the battery is overcharged. Therefore, even if service time of the battery increases, the voltage sensing component will not be easily triggered so long as overcharging does not occur, such that normal use of the battery is ensured.

Description

Battery top cover assembly and secondary battery

Technical field

The present application relates to the technical field of battery structures, and in particular, to a battery top cover assembly and a secondary battery.

Background technique

Secondary batteries have been widely used due to their ability to be repeatedly charged and discharged, and the problem of overcharging is a serious problem that secondary batteries need to face during use, especially for EV hard-shell batteries. The adverse effects are even more pronounced.

In order to solve the problem of overcharge, a commonly used solution in the related art is to cut off the main circuit of the battery before the failure of the battery, thereby preventing the battery from continuing to be charged to ensure battery safety. For example, it is possible to use a phenomenon in which a large amount of gas is generated when the battery is overcharged, and the circuit is interrupted by the action of the gas, so that the circuit cutting structure cuts off the main circuit of the battery.

However, the secondary battery also generates a certain amount of gas during normal use, and as the use time increases, more and more gas is generated in the secondary battery, which causes the secondary battery to be in normal use. It is also possible that the circuit cut-off structure is triggered. Obviously, this situation will seriously affect the normal use of the secondary battery.

Summary of the invention

The present application provides a battery top cover assembly and a secondary battery to solve the above drawbacks.

A first aspect of the present application provides a battery cap assembly including a first pole assembly, a second pole assembly, a top cover sheet, and a voltage sensing member having unidirectional conductivity, the second pole assembly Electrically connected to the top cover sheet, the voltage sensing component is located between the first pole assembly and the top cover sheet,

In a normal operating state, the first pole assembly and the top cover sheet apply a reverse voltage to the voltage sensing component, and when the voltage of the battery exceeds a reference voltage, the voltage sensing component is reversely broken.

Preferably, the first pole assembly is a negative pole assembly, and the second pole assembly is positive a pole post assembly; the voltage sensing component is a diode.

Preferably, the voltage sensing component is a transient suppression diode.

Preferably, the voltage sensing component is a silicon diode.

Preferably, the battery has a reference voltage of 4.5V.

Preferably, the first pole assembly includes a first pole body and a first terminal plate, the first pole body passes through the top cover sheet, the first terminal plate and the first pole The body is connected and located above the top cover sheet, and the voltage sensing component is located between the first terminal board and the top cover sheet.

A second aspect of the present application provides a secondary battery comprising a battery core and the battery top cover assembly of any of the above, the battery core comprising a first pole piece, a second pole piece, and the a separator between the pole piece and the second pole piece, the first pole piece is electrically connected to the first pole piece assembly, and the second pole piece is electrically connected to the second pole piece assembly;

When the voltage of the secondary battery exceeds the reference voltage, the voltage sensing component is reversely broken down, forming through the second pole piece, the second pole piece assembly, the top cover piece, and the voltage sensing Electrical connection paths of the component, the first pole assembly, and the first pole piece.

Preferably, the method further includes a fuse portion electrically connected to the charge and discharge circuit formed between the first pole assembly, the second pole assembly, and the battery core.

Preferably, the fuse portion is a sheet-like structure, the fuse portion is connected in series between the first pole assembly and the first pole piece, and/or the fuse portion is connected in series to the second pole Between the column assembly and the second pole piece.

Preferably, the voltage sensing component is a sheet-like structure, the voltage sensing component has a through hole, and the fuse portion includes a connected cell connection portion and a pole connection portion, and one end of the pole connection portion is worn. Passing through the through hole and electrically connecting to the first pole assembly.

Preferably, the fuse portion is a columnar structure, the first pole assembly is fixedly and electrically connected to the fuse portion, and the cross-sectional dimension of the first pole assembly is larger than a cross-sectional dimension of the fuse portion.

Preferably, the first pole assembly includes a first body segment and a second body segment, the fuse portion being connected in series between the first body segment and the second body segment, the first body segment Both the cross-sectional dimension and the cross-sectional dimension of the second body segment are greater than the cross-sectional dimension of the fuse portion.

Preferably, the first body segment, the second body segment and the fuse portion are integrated Structure.

Preferably, the outer peripheral surface of the fuse portion has an annular concave surface with respect to the first pole assembly in a circumferential direction of the first pole assembly.

Preferably, the cross-sectional shape of the annular recessed surface is a circular arc shape in a section obtained along the axial direction of the fuse portion.

Preferably, the voltage sensing components are plural, and each of the voltage sensing components is arranged along a surface where the top cover sheets are located.

Preferably, the voltage sensing components are disposed in two, respectively a first sensing component and a second sensing component, and in the radial direction of the first pole component, the first sensing component and the second sensing component They are respectively disposed on opposite sides of the first pole assembly.

Preferably, the voltage sensing component is a sheet structure or a columnar structure.

The technical solution provided by the present application can achieve the following beneficial effects:

The battery top cover assembly provided by the present application is provided with a voltage sensing component. When the battery has an overcharge problem, the potential difference between the positive electrode and the negative electrode is increased, and the voltage is induced by the first pole assembly and the top cover plate under normal working conditions. The component applies a reverse voltage, so current cannot flow from the positive electrode to the negative electrode. When the reverse voltage applied to the voltage sensing component (ie, the potential difference between the positive and negative electrodes) exceeds the reference voltage, the voltage sensing component is reversed. When worn, current can flow from the positive electrode to the negative electrode to form an external short circuit, thereby improving the safety performance of the battery. Obviously, the trigger condition of the voltage sensing component in the battery cap assembly is voltage, and the voltage on the voltage sensing component only changes sharply when the battery is overcharged, so even if the battery usage time increases, the voltage sensing component It is also not easy to trigger when there is no overcharge problem, so as to better ensure the normal use of the battery.

The above general description and the following detailed description are merely exemplary and are not intended to limit the application.

DRAWINGS

1 is an exploded view of a battery top cover assembly according to an embodiment of the present application;

2 is a cross-sectional view of a secondary battery provided by an embodiment of the present application;

Figure 3 is a cross-sectional view of the battery top cover assembly of Figure 1;

Figure 4 is an enlarged view of a portion A of Figure 3;

FIG. 5 is an exploded view of another battery top cover assembly according to an embodiment of the present application; FIG.

Figure 6 is a cross-sectional view of the battery top cover assembly of Figure 5;

Figure 7 is an enlarged view of a portion B of Figure 6;

FIG. 8 is an exploded view of still another battery top cover assembly according to an embodiment of the present application; FIG.

Figure 9 is a cross-sectional view showing a secondary battery to which the battery top cover assembly shown in Figure 8 is applied;

Figure 10 is a cross-sectional view of the battery top cover assembly of Figure 8;

Figure 11 is an enlarged view of a portion C of Figure 10;

12 is an exploded view of still another battery top cover assembly according to an embodiment of the present application;

Figure 13 is a cross-sectional view of the battery top cover assembly of Figure 12;

Figure 14 is a cross-sectional view taken along line D-D of Figure 13;

FIG. 15 is a schematic diagram of a mounting direction of a voltage sensing component in a battery top cover assembly according to an embodiment of the present application.

Reference mark:

10-cell;

11-shell;

20-first pole assembly;

200-first pole body, 201-first terminal plate, 202-first body segment; 203-second body segment;

21-second pole assembly;

210-second pole body, 211-second terminal plate;

22-top cover sheet;

25-first insulating member;

26-second insulating member;

27-third insulating member;

28-first seal;

29-second seal;

30-voltage sensing component;

30a-first sensing member; 30b-second sensing member;

31-fused part;

32-first adapter piece;

33-second adapter piece.

The drawings herein are incorporated in and constitute a part of the specification,

detailed description

The present application will be further described in detail below through specific embodiments and with reference to the accompanying drawings.

The present application relates to a secondary battery having a structure as shown in FIGS. 2 and 9, which may include a battery cell 10, a housing 11, and a battery top cover assembly. The battery top cover assembly may include a first pole assembly 20, a second pole assembly 21, a top cover sheet 22, a first insulating member 25, a second insulating member 26, a third insulating member 27, a first sealing member 28, The second seal 29 and the voltage sensing member 30.

The housing 11 can be an aluminum casing, and the cover sheet 22 and the housing 11 are closed to form a receiving cavity in which the battery core 10 is housed. The battery cell 10 includes a first pole piece, a second pole piece, and a separator between the first pole piece and the second pole piece. The first pole piece may be a positive electrode piece or a negative electrode piece; accordingly, the second pole piece may be a negative electrode piece or a positive electrode piece. The first pole assembly 20 and the second pole assembly 21 are mounted on the top cover sheet 22, and the first pole assembly 20 can be a positive pole, and correspondingly, the second pole assembly 21 is a negative pole, or a first pole The assembly 20 is a negative electrode column, and correspondingly, the second pole assembly 21 is a positive electrode column. The positive electrode column is electrically connected to the positive electrode tab of the battery cell 10, and the negative electrode column is electrically connected to the negative electrode tab of the battery cell 10. The first pole assembly 20 is insulatively connected to the second insulating member 26, and the second insulating member 26 is insulatively connected to the lower portion of the top cover sheet 22. The first sealing member 28 is disposed on the first pole assembly 20 and the second insulating member 26. between. The second pole assembly 21 is insulatively connected to the third insulating member 27, the third insulating member 27 is insulatively connected to the lower surface of the top cover sheet 22, and the second sealing member 29 is disposed on the second pole assembly 21 and the third insulating member 27. between.

The voltage sensing component 30 has unidirectional conductivity between the first pole assembly 20 and the top cover sheet 22. The first pole assembly 20 and the top cover sheet 22 apply a reverse voltage to the voltage sensing component 30, and the voltage sensing component 30 can sense the voltage difference between the first pole assembly 20 and the top cover sheet 22. The voltage sensing part 30 may employ a diode or other structure as long as it has a function of inducing a voltage and has unidirectional conductivity itself. Preferably, the first pole assembly 20 is a cathode pole assembly, the second pole assembly 21 is a positive pole assembly, and the voltage sensing component 30 is a diode. As shown in FIG. 15, since the voltage sensing component 30 has unidirectional conductivity, the first pole assembly 20 And the top cover sheet 22 applies a reverse voltage to the voltage sensing component 30, so in the normal operating state, the resistance of the positive to negative electrode of the voltage sensing component 30 is a large resistance value (corresponding to insulation), and the resistance value of the negative electrode to the positive electrode It is a small resistance value, so current cannot flow from the positive electrode to the negative electrode. Further, when the voltage sensing unit 30 is a diode, a transient suppression diode, that is, a TVS (Transient Voltage Suppressor) diode can be further used. This diode has an extremely fast response time (sub-nanoseconds) and a relatively high surge absorption capability. When both ends are subjected to an instantaneous high-energy impact, the impedance between the two ends can be extremely high. From high impedance to low impedance to absorb a large instantaneous current, clamping its own voltage across a predetermined value to protect other circuit components from transient high voltage spikes. Moreover, the TVS diode has a higher current conducting capability, thereby forming an external short circuit faster and preventing the battery from overcharging.

In terms of material, the voltage sensing component 30 can preferably be a silicon diode because the silicon diode has a smaller on-voltage than the diode of other materials, so that the overcharge phenomenon can be fed back more quickly, and silicon is additionally provided. When the diode is turned on, it has a larger current increase rate, and an external short circuit can be formed more quickly. Therefore, diodes of this material can better achieve overcharge protection of the battery.

In the normal operating state, since the voltage sensing component 30 has unidirectional conductivity, it is located between the first pole assembly 20 and the top cover sheet 22, and the first pole assembly 20 and the top cover sheet 22 apply to the voltage sensing component 30. The reverse voltage, so the current cannot flow from the positive electrode to the negative electrode; when the voltage of the battery exceeds the reference voltage, that is, when the battery is overcharged, the potential difference between the positive electrode and the negative electrode increases, since the voltage sensing member 30 is disposed on the top cover sheet 22 Between the first pole assembly 20 and the first pole assembly 20 and the top cover 22 apply a reverse voltage to the voltage sensing component 30 when applied to the reverse voltage on the voltage sensing component 30 (ie, the positive and negative electrodes) When the potential difference between the two exceeds the reference voltage, the voltage sensing member 30 is reversely broken, and the voltage sensing member 30 at this time loses unidirectional conductivity, and at this time, current can flow from the positive electrode to the negative electrode. Thereafter, an external short circuit is formed between the first pole assembly 20 and the second pole assembly 21 to improve the safety performance of the battery. In order to better explain the above principle, the following is an example in which the voltage sensing component 30 is a diode: the diode is forward-conducting, and when a reverse voltage is applied across the diode, the electron cannot pass through the diode, so that the diode is equivalent to an open circuit, but the open circuit depends on When the diode is reversed. If the voltage across the diode (ie, the reverse voltage) is large enough, the diode is reversed in reverse. The diode loses unidirectional conductivity during reverse breakdown, and the electrons pass through the diode, making the diode equivalent to the conductor. If diode If there is no overheating due to electrical breakdown, the unidirectional conductivity will not be permanently destroyed. After the voltage is removed, the performance can still be restored. Therefore, the overcharged battery can be used as long as the voltage is lowered.

Obviously, the trigger condition of the voltage sensing component 30 in the above battery cap assembly is a voltage, and the voltage on the voltage sensing component 30 usually only changes abruptly when the battery is overcharged, so even if the battery usage time is continuously increased, The voltage sensing component 30 is also not easy to trigger when there is no overcharge problem, thereby better ensuring the normal use of the battery.

It should be noted that the specific magnitude of the trigger voltage of the voltage sensing component 30 can be flexibly selected according to factors such as battery specifications and safety requirements. For example, the aforementioned reference voltage may be 4.5V. Under normal operating conditions of the battery, the insulation resistance of the voltage sensing component 30 from the positive electrode to the negative electrode may be greater than 1 Mohm. After the voltage sensing component 30 is reversely broken down, the voltage sensing component 30 is from the positive electrode to the negative electrode. The resistance can be 0.1 to 3 mohm.

The structure of the first pole assembly 20 is relatively diverse. In the embodiment of the present application, the first pole assembly 20 can include a first pole body 200 and a first terminal block 201. The first pole body 200 passes through the top cover sheet. 22, the first terminal block 201 is connected to the first pole body 200 and above the top cover sheet 22, and the voltage sensing member 30 is located between the first terminal block 201 and the top cover sheet 22. Similarly, the second pole assembly 21 can include a second pole body 210 and a second terminal plate 211, the second pole body 210 passes through the top cover sheet 22, and the second terminal plate 211 and the second pole body 210 Connected and located above the top cover sheet 22. Such an embodiment can better achieve the connection between the first pole assembly 20 and the second pole assembly 21 and the cover sheet 22.

Based on the above structure, the embodiment of the present application further provides a secondary battery including the battery core 10 and the battery top cover assembly described in any of the above embodiments, the battery core 10 includes a first pole piece, a second pole piece, and a separator between the first pole piece and the second pole piece, the first pole piece is electrically connected to the first pole piece assembly 20, and the second pole piece is electrically connected to the second pole piece assembly 21;

When the voltage of the secondary battery exceeds the reference voltage, the voltage sensing component 30 is broken down to form a second pole piece, a second pole assembly 21, a top cover sheet 22, a voltage sensing component 30, and a first pole assembly 20 in sequence. And the electrical connection path of the first pole piece, thereby improving the safety performance of the battery.

The voltage sensing component 30 provided by the embodiment of the present application may adopt a sheet structure, a columnar structure, or the like. When the sheet-like structure is employed, the space occupied by the voltage sensing member 30 in the height space of the battery is small; when the columnar structure is employed, the overall size of the voltage sensing member 30 can be controlled to be relatively small. During the specific implementation process, the voltage sense can be flexibly selected according to the actual situation. The size of the parameters such as the shape and size of the component 30 should be used.

In addition, the voltage sensing component 30 can be set to one (as shown in Figures 5-7), two or more. When the voltage sensing component 30 is disposed in plurality, the voltage sensing components 30 may be arranged along the surface where the top cover sheet 22 is located, thereby increasing the voltage sensing component 30 and the first pole assembly 20 (or the second pole) The reliability of the assembly 21) after contact with the top cover sheet 22. More preferably, based on the overall size of the battery cover assembly, the voltage sensing component 30 can be disposed in two, respectively, the first sensing component 30a and the second sensing component 30b shown in FIGS. 1-4. In the radial direction of the pole assembly 20, the first sensing member 30a and the second sensing member 30b may be respectively disposed on opposite sides of the first pole assembly 20. Such an arrangement can not only improve the reliability of the voltage sensing component 30 after contact with the first pole assembly 20 (or the second pole assembly 21) and the top cover sheet 22, but also enable the voltage sensing components 30 and the first pole. The force between the column assembly 20 (or the second pole assembly 21) and the top cover sheet 22 is more evenly balanced.

Although the battery top cover assembly provided by the present application can alleviate the overcharge problem of the battery, when the voltage sensing member 30 is broken down, it is still impossible to reliably ensure that the battery 10 does not continue to be charged. Therefore, in order to more thoroughly prevent the battery from overcharging, the battery may further include a fuse portion 31 electrically connected to the charge formed between the first pole assembly 20, the second pole assembly 21 and the battery cell 10. On the discharge circuit. The charge and discharge circuit here refers to a circuit formed when the battery is normally charged and discharged. When the voltage sensing component 30 is broken down, an external short circuit is formed between the first pole assembly 20 and the second pole assembly 21, and a relatively large current is passed through the fuse portion 31, so that the fuse portion 31 itself is thermally disconnected to at least In two parts, the entire charge and discharge circuit will be disconnected and the charging process of the battery will be completely completed. Therefore, after the fuse portion 31 is provided, the charge and discharge circuit can be cut off at the initial stage of the battery overcharge problem, so that the battery 10 does not continue to be charged.

The structure of the fuse portion 31 can be flexibly set. For example, the fuse portion 31 can adopt a sheet-like structure to facilitate the fuse portion 31 to be blown more quickly. The present application provides the following three ways. Of course, the fuse portion 31 can also adopt other structures.

In the first type, the fuse portion 31 adopts a sheet structure, and the fuse portion 31 may be connected in series between the first pole assembly 20 and the first pole piece, or may be connected in series between the second pole assembly 21 and the second pole piece. Alternatively, the fuse portion 31 is connected in series between the first pole assembly 20 and the first pole piece, and between the second pole assembly 21 and the second pole piece. As shown in FIG. 2, the fuse portion 31 is connected in series between the second pole assembly 21 and the second pole piece, that is, one side of the fuse portion 31 is directly fixed and electrically connected to the second pole assembly 21. The other side is directly fixed and electrically connected to the battery cell 10, and the first pole assembly 20 is electrically connected to the battery cell 10 through the first adapter piece 32.

Secondly, as shown in FIGS. 12-14, the fuse portion 31 can still adopt a sheet-like structure, and the voltage sensing member 30 can also adopt a sheet-like structure. The first pole assembly 20 under such a structure can include only the first terminal. Board 201. A through hole may be formed in the voltage sensing component 30. The fuse portion 31 may include a connected cell connection portion and a pole connection portion. One end of the pole connection portion passes through the through hole and is electrically connected to the first terminal block 201. In this structure, the cell connection portion can adopt a relatively large connecting piece to ensure a sufficient contact area between the fuse portion 31 and the cell 10; and the pole connecting portion can adopt a connecting piece having a relatively small area to The size of the through hole is minimized to ensure the resistance value of the voltage sensing member 30 from the positive electrode to the negative electrode while controlling the size of the voltage sensing member 30.

Third, as shown in FIGS. 8-11, the fuse portion 31 may have a columnar structure. In this configuration, the first pole assembly 20 is electrically connected to the battery core 10 through the first adapter piece 32, and the second pole assembly 21 is electrically connected to the battery core 10 through the second adapter piece 33. Further, the first pole assembly 20 can be fixed and electrically connected to the fuse portion 31. Specifically, the axis of the first pole assembly 20 can be parallel to the axis of the fuse portion 31. At this time, in order to ensure that the fuse portion 31 can be blown, the cross-sectional dimension of the first pole assembly 20 may be larger than the cross-sectional size of the fuse portion 31. When the current passes through the first pole assembly 20 and the fuse portion 31, since the cross-sectional dimension of the fuse portion 31 is relatively small, the structure of the fuse portion 31 is made weaker, thereby achieving the purpose of the fuse portion 31 being blown.

The columnar fuse portion 31 may be disposed at one end of the first pole assembly 20, and in another structure, as shown in FIG. 11, the first pole assembly 20 (when the first pole assembly 20 includes the first pole In the case of the body 200 and the first terminal block 201, specifically, the first pole body 200) may include a first body segment 202 and a second body segment 203, and the fuse portion 31 is connected in series to the first body segment 202 and the second body segment 203. In other words, that is, the fuse portion 31 is electrically connected between the first body segment 202 and the second body segment 203. The cross-sectional dimension of the first body segment 200 and the cross-sectional dimension of the second body segment 203 are both larger than the cross-sectional dimension of the fuse portion 31 to effect fusing of the fuse portion 31. Preferably, the first body segment 202, the second body segment 203, and the fuse portion 31 may be of a unitary structure to improve the structural strength and reliability of the secondary battery.

When the cross-sectional dimension of the first pole assembly 20 is designed to be larger than the cross-sectional dimension of the fuse portion 31, one side of the columnar fuse portion 31 may be aligned with the side of the first pole assembly 20, and even the first pole may be exceeded. The side of the column assembly 20, but both structures will make the first pole set The structure composed of the member 20 and the fuse portion 31 has a relatively serious irregularity, resulting in a high processing cost of the battery top cover assembly. In view of this, the outer peripheral surface of the fuse portion 31 can be disposed such that the outer peripheral surface of the fuse portion 31 is annularly recessed with respect to the first pole assembly 20 in the circumferential direction of the first pole assembly 20. With such a structure, the structure of the fuse portion 31 is more regular, thereby facilitating the processing of the entire battery top cover assembly.

The annular recessed surface may be a cylindrical surface, a prism surface or the like. However, if the interface shape of the annular concave surface is linear in the section obtained along the axial direction of the fuse portion 31, the fuse portion 31 and the first pole assembly The connection between the 20 will be more abrupt, resulting in a break between the two due to external forces. To this end, the shape of the annular recessed surface along the aforementioned direction may be set to a circular arc shape, so that the fuse portion 31 may be in a circular arc transition connection with the first pole assembly 20. When the first pole assembly 20 includes the first body segment 202 and the second body segment 203, the fuse portion 31 can be simultaneously arcuately coupled with the first body segment 202 and the second body segment 203.

The above description is only the preferred embodiment of the present application, and is not intended to limit the present application, and various changes and modifications may be made to the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application are intended to be included within the scope of the present application.

Claims

A battery top cover assembly, comprising: a first pole assembly, a second pole assembly, a cover sheet, and a voltage sensing component having unidirectional conductivity, the second pole assembly and the top cover The sheet is electrically connected, and the voltage sensing component is located between the first pole assembly and the top cover sheet.

In a normal operating state, the first pole assembly and the top cover sheet apply a reverse voltage to the voltage sensing component, and when the voltage of the battery exceeds a reference voltage, the voltage sensing component is reversely broken.
The battery cap assembly of claim 1 wherein said first pole assembly is a cathode pole assembly, said second pole assembly is a positive pole assembly; and said voltage sensing component is a diode.
The battery cap assembly of claim 2 wherein said voltage sensing component is a transient suppression diode.
The battery cap assembly of claim 2 wherein said voltage sensing component is a silicon diode.
The battery top cover assembly of claim 1 wherein said battery has a reference voltage of 4.5V.
The battery cap assembly according to any one of claims 1 to 5, wherein the first pole assembly comprises a first pole body and a first terminal plate, the first pole body passes through The top cover sheet is connected to the first pole body and located above the top cover sheet, and the voltage sensing component is located in the first terminal board and the top cover sheet between.
A secondary battery, comprising: a battery core, and the battery top cover assembly according to any one of claims 1 to 6, wherein the battery core includes a first pole piece, a second pole piece, and the a separator between the pole piece and the second pole piece, the first pole piece is electrically connected to the first pole piece assembly, and the second pole piece is electrically connected to the second pole piece assembly;

When the voltage of the secondary battery exceeds the reference voltage, the voltage sensing component is reversely broken down, forming through the second pole piece, the second pole piece assembly, the top cover piece, and the voltage sensing Electrical connection paths of the component, the first pole assembly, and the first pole piece.
The secondary battery according to claim 7, further comprising a fuse portion, The fuse portion is electrically connected to the charge and discharge circuit formed between the first pole assembly, the second pole assembly and the battery core.
The secondary battery according to claim 8, wherein the fuse portion is a sheet-like structure, the fuse portion is connected in series between the first pole assembly and the first pole piece, and/or The fuse portion is connected in series between the second pole assembly and the second pole piece.
The secondary battery according to claim 9, wherein the voltage sensing member has a sheet-like structure, the voltage sensing member has a through hole, and the fuse portion includes a connected cell connection portion and a pole And a connecting portion, one end of the pole connecting portion passes through the through hole, and is electrically connected to the first pole assembly.
The secondary battery according to claim 8, wherein the fuse portion is a columnar structure, the first pole assembly is fixedly and electrically connected to the fuse portion, and a cross section of the first pole assembly The size is larger than the cross-sectional dimension of the fuse.
The secondary battery according to claim 11, wherein the first pole assembly comprises a first body segment and a second body segment, the fuse portion being connected in series to the first body segment and the second Between the body segments, the cross-sectional dimension of the first body segment and the cross-sectional dimension of the second body segment are both greater than the cross-sectional dimension of the fuse portion.
The secondary battery according to claim 12, wherein the first body segment, the second body segment, and the fuse portion are of a unitary structure.
The secondary battery according to claim 13, wherein an outer peripheral surface of the fuse portion is annularly recessed with respect to the first pole assembly in a circumferential direction of the first pole assembly.
The secondary battery according to claim 14, wherein a cross-sectional shape of the annular recessed surface is a circular arc shape in a cross section obtained along an axial direction of the fuse portion.
The secondary battery according to claim 7, wherein the plurality of voltage sensing members are arranged, and each of the voltage sensing members is arranged along a surface on which the top cover sheet is located.
The secondary battery according to claim 16, wherein the voltage sensing members are provided in two, respectively a first sensing member and a second sensing member, in a radial direction of the first pole assembly, The first sensing member and the second sensing member are respectively disposed on opposite sides of the first pole assembly.
The secondary battery according to claim 7, wherein the voltage sensing member is a sheet structure or a columnar structure.