WO2018090180A1

WO2018090180A1 - Secondary battery

Info

Publication number: WO2018090180A1
Application number: PCT/CN2016/105866
Authority: WO
Inventors: 蔡如来; 林永寿; 李全坤; 杨伟; 王鹏
Original assignee: 宁德时代新能源科技股份有限公司
Priority date: 2016-11-15
Filing date: 2016-11-15
Publication date: 2018-05-24
Also published as: CN109792032B; CN109792032A

Abstract

Provided is a secondary battery, comprising an electrode assembly (31), a first terminal (11) and a second terminal (21), and a top cover sheet (41). The electrode assembly (31) comprises a first pole piece and a second pole piece. The first terminal (11) is electrically connected to the first pole piece, and the second terminal (21) is electrically connected to the second pole piece. The secondary battery further includes: a first resistance member (18), a second resistance member (24), a contact piece (12) attached to the first terminal (11), and a conductive piece (22) electrically connected to the second terminal (21). The top cover sheet (41) is always electrically connected to the first terminal (11) through the first resistance member (18), and the top cover sheet (41) is insulated from the second terminal (21) and the conductive piece (22). When the internal pressure of the secondary battery exceeds a reference pressure, the contact piece (12) is in contact with the conductive piece (22) to form an electrical connection path through the first pole piece, the first terminal (11), the contact piece (12), the conductive piece (22), the second terminal piece (21) and the second pole piece. The second resistance member (24) is serially connected in the path, the resistance of the first resistive member (18) being greater than that of the second resistance member (24). The scheme realizes the protection of the secondary battery in two aspects and improves the safety of the secondary battery.

Description

Secondary battery

Technical field

The present application relates to the field of energy storage devices, and in particular, to a secondary battery.

Background technique

Electric vehicles and energy storage power stations and the like generally require the use of a secondary battery having a large capacity as a power source. In addition to their high capacity, these secondary batteries should also have good safety in order to meet the standards of use and meet people's needs.

On the one hand, when the secondary battery is passed through from the outside by the conductor, there is a short circuit between the first piece and the second piece inside the battery core, and at this time, a resistor is usually disposed between the top cover piece and the pole piece, and The resistance value of the resistor is usually large to reduce the short-circuit current through the first piece and the second piece to avoid runaway of the cell.

On the other hand, when the secondary battery is in a rapid charging or high-power discharging process, the inside generates excessive heat, and the electrolyte may be decomposed, and the generation of such heat and the decomposition of the electrolyte cause the pressure inside the secondary battery to increase. It may cause the secondary battery to catch fire and explode. At this time, an external short-circuit structure is often used, for example, a contact piece is connected on the top cover sheet, and a conductive sheet is connected on the pole, and the contact piece is turned over to electrically contact the conductive sheet to replace the secondary battery. The short circuit between the first piece and the second piece is short-circuited, and the short-circuit circuit has a fuse portion connected in series, so that the short-circuit current can blow the fuse portion, cut off the current circuit, and stop the charging and discharging states of the secondary battery, which requires a short-circuit circuit. The resistance value in the middle is small, otherwise the fuse cannot be blown. However, the above two aspects make the secondary battery appear contradictory in the selection of the resistance value.

In the related art, the above contradiction can be solved by providing two contact pieces in the secondary battery, but the consistency of the two contact piece flipping is higher, otherwise, if one of the two contact pieces cannot be flipped Will reduce the safety of the secondary battery.

Summary of the invention

The embodiment of the present application provides a secondary battery, which can improve the above defects.

A first aspect of the present application provides a secondary battery including: an electrode assembly, first and second terminals, and a cover sheet,

The electrode assembly includes a first pole piece, a second pole piece, and a partition disposed between the first pole piece and the second pole piece, the first terminal being electrically connected to the first pole piece The second terminal is electrically connected to the second pole piece,

The secondary battery further includes: a first resistance member, a second resistance member, a contact piece attached to the first terminal, and a conductive piece electrically connected to the second terminal,

The top cover sheet is always electrically connected to the first terminal through the first resistance member, and the top cover sheet is insulated from the second terminal and the conductive sheet,

And when the internal pressure of the secondary battery exceeds a reference pressure, the contact piece acts under the action of air pressure and contacts the conductive sheet to form through the first pole piece, the first terminal, the Electrical connection paths of the contact piece, the conductive piece, the second terminal, and the second pole piece,

The second resistance member is connected in series in the electrical connection path, and the resistance of the first resistance member is greater than the resistance of the second resistance member.

Preferably, further comprising a housing, the cover sheet covering the housing to form a first chamber for encapsulating the electrode assembly and a second chamber for providing an action space for the contact piece,

The first chamber and the second chamber are separated by the contact piece, and the conductive sheet is located on a side of the top cover sheet away from the electrode assembly.

Preferably, the top cover sheet is provided with a through hole, and the conductive sheet has a contact portion capable of contacting the contact piece after the action, and the contact portion is located in the second chamber.

Preferably, the cover sheet includes a body portion and a raised portion, the raised portion protruding toward a side away from the housing, the second chamber being surrounded by the contact piece and the raised portion, and The through hole is disposed on the raised portion.

Preferably, the first terminal comprises a connected terminal body and an extension,

An opening is formed in the extension, the opening is opposite to the through hole, and the contact piece seals the opening to separate the first chamber from the second chamber.

Preferably, the terminal body and the extension are a unitary structure or a split structure.

Preferably, further comprising a sealing member sealed between the first chamber and the second chamber, the sealing member being sealingly coupled between the extension and the top cover sheet, and A first sealing surface in sealing contact with the top cover sheet and a second sealing surface in sealing contact with the extension portion.

Preferably, further comprising a sealing member sealed between the first chamber and the second chamber, the sealing member being sealed between the contact piece and the top cover sheet, and having The top cover sheet sealingly contacts the first sealing surface and the second sealing surface in sealing contact with the contact piece.

Preferably, the first sealing surface and the second sealing surface are oppositely disposed along an extending direction of the top cover sheet, and/or

The first sealing surface and the second sealing surface are disposed opposite to each other in a height direction of the secondary battery.

Preferably, the contact piece comprises a turning portion and a protruding head,

The turning portion is a sheet-shaped torus structure,

The protrusion is coupled to the inversion portion and protrudes toward a side of the top cover sheet,

An outer edge of the inversion portion is sealingly coupled to the extension portion, and the contact piece is in contact with the contact portion through the protrusion when the contact piece is inverted.

Preferably, further comprising a first terminal plate electrically connected to the first terminal plate, the first resistance member being connected in series between the first terminal plate and the top cover sheet.

Preferably, the first resistance member has a first end and a second end,

a first recess is formed on the top cover sheet, and the first end is embedded in the first recess.

and / or

A second recess is formed on the first terminal plate, and the second end is embedded in the second recess.

Preferably, a second terminal plate is further included, the second terminal is electrically connected to the second terminal plate, and the second resistance member is connected in series between the second terminal plate and the conductive sheet.

Preferably, the resistance of the first resistance member is at least 1000 times the resistance of the second resistance member.

Preferably, the resistance value of the second resistance member ranges from 1 ohm to 100,000 ohms, and the resistance value of the second resistance member ranges from 0.1 milliohm to 100 milliohm.

Preferably, further comprising a fuse member, the fuse member being connected in series through the first pole In the electrical connection path of the sheet, the first terminal, the contact piece, the conductive piece, the second terminal and the second pole piece, an overcurrent area at the fuse member is smaller than the electrical connection The overcurrent area of the rest of the path; and

The fuse member is connected in series between the first pole piece and the first terminal, and/or

The fuse member is connected in series between the second pole piece and the second terminal.

Preferably, the method further includes a first connecting member and a second connecting member,

The first pole piece is electrically connected to the first terminal through the first connecting member, and the second pole piece is electrically connected to the second terminal through the second connecting piece,

The fuse member is formed on the first connecting member and/or the second connecting member.

Preferably, the fusible member is formed by opening a notch and/or a hole in the first connector and/or the second connector.

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

The present application provides a secondary battery including a top cover sheet, a first terminal, a second terminal, a contact piece, a conductive sheet, and a first resistance member and a second resistance member. In one aspect, the top cover sheet is always electrically connected to the first terminal via the first resistance member, and passes through the first when the inside of the secondary battery is passed by the conductor and the first pole piece of the battery cell is short-circuited with the second pole piece The resistance member is connected in series in the shorting path, so that the short-circuit current is reduced, the heat generation inside the battery core is controlled, the probability of occurrence of an accident of the secondary battery is reduced, and the safety of the secondary battery is improved; on the other hand, the contact The sheet is attached to the first terminal, and the conductive sheet is electrically connected to the second terminal. When the internal pressure value of the secondary battery increases and exceeds the reference pressure value, the contact piece acts under the action of the air pressure and contacts the conductive sheet to form Passing an electrical connection path short-circuited between the first pole piece and the second pole piece such that the overcharge state of the secondary battery is stopped, and since the second resistance member is connected in series in the electrical connection path, the electrical connection path is consumed Part of the electric energy reduces the short-circuit current at the moment when the contact piece contacts the conductive piece, thereby reducing the risk of fire and explosion of the secondary battery and improving the safety of the secondary battery. In the present application, the electrical connection path formed after the contact piece is in contact with the conductive piece and the electrical connection path where the first resistance member is located belong to two different paths, thereby solving the contradiction in setting the resistance, and realizing two for the secondary battery. The protection of the aspect improves the safety of the secondary battery.

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

DRAWINGS

1 is a perspective exploded view of a secondary battery according to an embodiment of the present application;

2 is a perspective exploded view of a portion of a secondary battery provided by an embodiment of the present application;

3 is a cross-sectional view showing a part of a structure of a secondary battery according to an embodiment of the present application;

4 is a cross-sectional view showing an exploded view of a first terminal and a contact piece according to an embodiment of the present application;

5 is a cross-sectional view showing a state in which a first terminal and a contact piece are connected according to an embodiment of the present application;

Figure 6 is an enlarged view of the portion A of Figure 3;

FIG. 7 is a schematic diagram of Embodiment 1 of a sealing structure sealed between a first chamber and a second chamber according to an embodiment of the present application; FIG.

8 is a schematic view showing a second embodiment of a sealing structure sealed between a first chamber and a second chamber according to an embodiment of the present application;

9 is a schematic view showing a third embodiment of a sealing structure sealed between a first chamber and a second chamber according to an embodiment of the present application;

Figure 10 is an enlarged view of the portion B of Figure 3.

Reference mark:

11-first terminal;

111-terminal body;

112-extension;

112a-opening;

112b-columnar;

112c-step surface;

12-contact piece;

121-protrusion;

121a-second contact plane;

122-turning section;

13-sealing member;

131-first sealing surface;

132-second sealing surface;

14-fuse member;

15-first terminal board;

16-first connector;

17-first insulating liner;

18-first resistance member;

21-second terminal;

22-conductive sheet;

221-contact portion;

221a-first contact plane;

23-insulating member;

231-hole;

24-second resistance member;

25-second terminal board;

26-second connector;

27-second insulating liner;

31-electrode assembly;

311-first ear;

312-second pole;

41-top cover sheet;

411- body part;

412-high rise portion;

413-through hole;

51-shell;

61-Insulation cover.

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 will be further described in detail below through specific embodiments and with reference to the accompanying drawings. The terms "front", "back", "left", "right", "upper", and "lower" as used herein refer to the state of placement of the secondary battery in the drawings.

As shown in FIG. 1-10, the embodiment of the present application provides a secondary battery including a first terminal 11 and a second terminal 21, and the first terminal 11 and the second terminal 21 may be connected to an external circuit. The current loop, the secondary battery acts as a power source in the external circuit, and outputs electric energy to the outside.

Wherein, the first terminal 11 can be used as a positive terminal, and accordingly, the second terminal 21 is used as a negative terminal, and vice versa. Hereinafter, the present application will be described in detail by taking the first terminal 11 as a positive electrode terminal (the first pole piece is a positive electrode piece) and the second terminal 21 as a negative electrode terminal (the second pole piece is a negative electrode piece) as an example.

As shown in FIG. 1, the secondary battery generally includes an electrode assembly 31, a top cover sheet 41, and a housing 51. The housing 51 and the top cover sheet 41 may be covered by welding or the like to form a receiving cavity, and the electrode assembly 31 is housed in the housing. The electrode assembly 31 is insulated from the casing 51 by an insulating cover 61 in the cavity.

The electrode assembly 31 generally includes a first pole piece and a second pole piece, the first pole piece has a first pole 311 thereon, and the second pole piece has a second pole 312 thereon, the first pole piece is connected to the first through the first pole 311 The terminal 11 is electrically connected, and the second pole piece is electrically connected to the second terminal 21 via the second tab 312, so that the electrical energy is finally output to the outside by the electrode assembly 31.

As shown in FIG. 2-3, the secondary battery provided by the embodiment of the present application further includes a conductive sheet 22, a contact piece 12, and a first resistance member 18 and a second resistance member 24, wherein the resistance of the first resistance member 18 is greater than The resistance of the second resistance member 24.

On one hand, the contact piece 12 is attached to the first terminal 11, and the conductive piece 22 is electrically connected to the second terminal 21. When the internal pressure of the secondary battery exceeds the reference pressure, the contact piece 12 operates under the action of the air pressure and the conductive piece 22 contacting to form an electrical connection path through the first pole piece, the first terminal 11, the contact piece 12, the conductive piece 22, the second terminal 21, and the second pole piece, and the second resistance member 24 is connected in series in the electrical connection path in.

The contact piece 12 and the first terminal 11 may be a one-piece structure or a split structure; the electrical connection between the conductive piece 22 and the second terminal 21 may be directly connected to the two. The conductive sheet 22 is connected to the second terminal 21 through other conductors. The present invention is not limited thereto, as long as the conductive sheet 22 and the second terminal 21 can achieve current conduction.

The contact piece 12 is operated under the action of air pressure and is in contact with the conductive piece 22 in a direct contact between the two, or another conductive body is disposed between the contact piece 12 and the conductive piece 22 so that the contact piece 12 and the conductive piece 22 are in indirect contact. .

According to the above description, during the charging and discharging process of the secondary battery, when the inside of the secondary battery excessively generates heat or the electrolyte is decomposed, and thus the internal pressure of the battery increases, and the internal pressure exceeds the reference pressure, The contact piece 12 operates under the action of air pressure and is in contact with the conductive sheet 22, so that the secondary battery forms an external short-circuit state, and the second resistance member 24 consumes part of the electric energy in the short-circuit circuit, thereby reducing the short-circuit current, thereby reducing the second The risk of secondary battery explosion and fire increases the safety of the secondary battery.

On the other hand, the top cover sheet 41 is always electrically connected to the first terminal 11 via the first resistance member 18, and the top cover sheet 41 is insulated from the second terminal 21 and the conductive sheet 22.

When the secondary battery is short-circuited between the first pole piece and the second pole piece by the conductor passing through (for example, performing a nailing test), the short-circuit current flows through the first pole piece, the casing, and the top cover piece 41. The first resistance member 18, the second terminal 11, the second pole piece, and the first resistance member 18 are disposed to significantly reduce the short-circuit current, thereby reducing the probability of a larger dangerous accident such as thermal runaway of the secondary battery, and improving The safety of the secondary battery.

In the above solution, the electrical connection path formed by the contact between the contact piece 12 and the conductive piece 22 and the electrical connection path of the first resistance member 18 belong to two different paths, thereby solving the contradiction in setting the resistance, and the secondary battery Two aspects of protection have been realized, and the safety of the secondary battery has been improved.

As shown in FIG. 3, the secondary battery further includes a first terminal plate 15 electrically connected to the first terminal 11, in which case the first resistance member 18 may be connected in series to the first terminal plate. Between the 15 and the top cover sheet 41, the short-circuit current flows through the top cover sheet 41, the first resistance member 18, the first terminal block 15, and the first terminal 11.

Accordingly, the second terminal plate 25 may be further included in the secondary battery, and the conductive sheet 22 is electrically connected to the second terminal 21 via the second terminal plate 25. Moreover, it should be noted that the arrangement of the first terminal plate 15 and the second terminal plate 25 can facilitate the first terminal 11 and the second. The connection between the terminal 21 and the external circuit is provided for ease of assembly, but is not necessary.

In the above case, the first resistance member 18 may be provided with a columnar resistor, and the first resistance member 18 may be directly fixed between the first terminal plate 15 and the top cover sheet 41, thereby facilitating the arrangement of the first resistance member 18.

Specifically, according to an embodiment, as shown in FIG. 2-3, the first resistance member 18 has a first end and a second end along the axial direction thereof, and the first cover portion 41 is provided with a first recess, the first resistance member The first end of the 18 is embedded in the first recess and the second end abuts the first terminal plate 15 such that the first resistive member 18 can be securely secured within the first recess.

According to another embodiment, a second recess may be formed on the first terminal plate 15, and the second end of the first resistance member 18 is embedded in the second recess, and the first end thereof is in contact with the top cover 41. By the way, the first resistance member 18 is also reliably fixed.

In addition, the above two embodiments may be combined, that is, the first cover portion is opened on the top cover sheet 41, and the second terminal portion is simultaneously opened on the first terminal plate 15, the first end of the first resistance member 18 and The second ends are respectively embedded in the first recess and the second recess. With this arrangement, both ends of the first resistance member 18 are simultaneously restrained, and the reliability of electrical connection with the first terminal plate 15 and the top cover sheet 41 is further improved.

It should be noted that one end of the first terminal 11 away from the top cover sheet 41 is electrically connected to the top cover sheet 41 via the first terminal plate 15, the first resistance member 18, and one end near the top cover sheet 31 passes through the first insulating spacer 17 It is insulated from the top cover sheet 41 to form a desired electrical connection path.

It should be understood by those skilled in the art that when the secondary battery is normally operated, the normal current sequentially flows through the first terminal block 15, the first terminal 11, and the first pole piece, and although the first resistance member 18 exists, it does not affect the normal operation. When the output of the secondary battery.

The resistance value of the first resistance member 18 may be selected between 1 ohm and 100,000 ohms, and the first resistance member 18 may be selected from a high temperature resistance, for example, a silicon carbide resistor and a conductive ceramic, and the resistance of the silicon carbide resistor is 10 ohms. The maximum withstand temperature is greater than 600 ° C, and the resistance of the conductive ceramic is 500 ohms. Further, the first resistance member 18 may also adopt a ring structure and may be fitted over the first terminal 11.

The second resistance member 24 functions to reduce the peak value of the short-circuit current, but in actuality, there is also a case where the short-circuit current fuses the contact portion of the contact piece 12 and the conductive sheet 22, thereby causing the electrode assembly 31 and the external circuit. Form an open circuit to avoid secondary electricity Dangerous accidents such as fire and explosion in the pool. The resistance value of the second resistance member 24 may be selected from the range of 0.1 milliohm to 100 milliohms. For example, the second resistance member 24 may be made of a material such as steel, stainless steel or nickel steel alloy.

The position of the second resistance member 24 may be selected according to the environment of the actual application, as shown in FIGS. 3 and 10, and the second resistance member 24 is disposed at the second terminal 21. This solution allows the second resistive member 24 to be less susceptible to heat generated by the contact of the contact strip 12 with the conductive sheet 22.

Specifically, the second resistance member 24 is connected in series between the second terminal plate 25 and the conductive sheet 22. When the contact piece 12 is in electrical contact with the conductive piece 22, the short-circuit current sequentially flows through the first pole piece, the first terminal 11, and the contact piece. 12. The conductive sheet 22, the second resistance member 24, the second terminal plate 25, the second terminal 21, and the second pole piece.

Similarly, when the secondary battery is normally operated, the normal current sequentially flows through the second terminal plate 25, the second terminal 21, and the second pole piece, and although the second resistance member 24 exists, it does not affect the secondary battery during normal operation. Output.

Usually, a portion of the first terminal 11 and the second terminal 21 respectively protrude outside the cover sheet 41, and the extended portion is connected to the external circuit. In some embodiments, the first terminal 11 may not necessarily protrude beyond the top cover sheet 41. For example, in the embodiment in which the first terminal 11 is used as a positive terminal, the first terminal 11 may be implemented via the cover sheet 41. Electrical connection of the circuit. Moreover, when the top cover sheet 41 is electrically connected to the first terminal 11 serving as a positive electrode, both the casing and the top cover sheet 41 are positively charged, and the corrosion of the electrolyte and the cover sheet 41 can be reduced and extended. Service life.

As shown in FIG. 3, more precisely, the housing chamber formed by the cover of the cover sheet 41 includes a first chamber S1 and a second chamber S2. Specifically, the first chamber S1 is used to encapsulate the electrode assembly 31, and the second chamber S2 is used to provide an action space for the contact piece 12, and the first chamber S1 and the second chamber S2 are separated by the contact piece 12. When the internal pressure of the first chamber S1 exceeds the reference pressure, the gas pressure acts on the contact piece 12 and pushes it to move.

The contact strip 12 after the action can make electrical contact with the conductive sheet 22, wherein the conductive sheet 22 is located on the side of the top cover sheet 41 away from the electrode assembly 31. The conductive sheets 22 may all be located inside the second chamber S2 or may be entirely outside the second chamber S2. When the conductive sheets 22 are all located outside the second chamber S2, the contact piece 12 is in electrical contact with the conductive sheet 22 The heat generated can be more easily dispersed by conduction.

In the embodiment shown in FIG. 3, a portion of the conductive sheet 22 is disposed in the second chamber S2, and the remaining portion is located outside the second chamber S2. This solution facilitates heat dissipation and facilitates electrical contact with the contact piece 12. Set in two ways.

Specifically, as shown in FIG. 2-3, the contact piece 12 is attached to the first terminal 11, the conductive piece 22 is disposed above the top cover piece 41 and connected to the second terminal 21, and the conductive piece 22 is from the second terminal 21. The cover sheet 41 is extended with a through hole 413. The conductive sheet 22 has a convex portion protruding toward the contact piece 12, and the protruding portion is electrically connected to the contact piece 12 after the action. The contact portion 221 of the contact portion 221 extends into the through hole 413 and is located in the second chamber S2. The arrangement of the contact portion 221 facilitates heat dissipation of the conductive sheet 22 and the interval between the conductive sheet 22 and the contact piece 12, This spacing enables the two to be in contact with each other when the contact piece 12 is in operation, and can be insulated from each other before the contact piece 12 is actuated.

Further, according to an embodiment, as shown in FIGS. 4-5, the contact piece 12 includes a protrusion 121 and a reversing portion 122, wherein the reversing portion 122 is a sheet-like toroidal structure, which facilitates the contact piece 12 to be realized under the action of air pressure. In operation, the boss 121 is connected to the inverting portion 122 and protrudes toward one side of the cap piece 41. When the contact piece 12 is actuated, the contact piece 12 can be in contact with the contact portion 221 through the tab 121. In this solution, the arrangement of the projections 121 can reduce the stroke of the contact piece 12 on the basis of an appropriate interval from the contact portion 221, thereby improving the safety of the secondary battery. Further, the boss 121 and the inverting portion 122 may be of a unitary structure.

Further, as shown in FIG. 6, the contact portion 221 has a first contact plane 221a, and correspondingly, the bump 121 has a second contact plane 121a. When the contact piece 12 is in contact with the conductive sheet 22, the first contact plane 221a and the first The two contact planes 121a are in electrical contact. This solution allows the contact strip 12 to have a large contact area when in contact with the conductive sheet 22 to ensure reliable electrical contact between the two.

For the conductive sheet 22, the conductive sheet 22 is fixed, and the side of the contact portion 221 facing the contact piece 12 serves as the first contact plane 221a. For the contact piece 12, the contact piece 12 is deformed after the action of the contact piece 12. Considering that the amount of deformation at the protrusion 121 is relatively small, the protrusion 121 is substantially in a planar state toward one side surface of the conductive piece 22, and therefore, The surface of the bump 121 facing the conductive sheet 22 may serve as the second contact plane 121a.

In the embodiment shown in FIG. 3, one end of the conductive piece 22 is connected to the second terminal 21, and the other end extends toward one side of the first terminal 11. Therefore, the conductive piece 22 is a cantilever with one end fixed and the other end being a free end. The structure, in the process of contacting with the contact piece 12, causes the conductive piece 22 to be displaced by the contact force, resulting in poor contact between the two. In order to overcome the above drawbacks, it is preferable to provide a connection structure at the free end of the conductive sheet 22 to fix the free end of the conductive sheet 22, which may be realized by a bonded structure or by a mating engagement structure.

As shown in FIG. 2-3, the secondary battery includes an insulating member 23 which is covered on the outside of the conductive sheet 22, and one end is fixed at the second terminal 21, and on the other hand, covered by the insulating member 23, The two are embedded together, and the insulating member 23 extends toward the first terminal 11 and is fixed at the first terminal 11. After being disposed, the cantilever structure of the conductive sheet 22 is alleviated by the support of the insulating member 23, which is reduced. The phenomenon that the conductive sheet 22 is in poor contact with the contact piece 12.

On the other hand, by the covering of the insulating member 23, only the contact portion 221 which is in contact with the contact piece 12 and the portion which is electrically connected to the second terminal 21 are exposed on the conductive sheet 22, thereby avoiding the contact with the top cover sheet 41. It is turned on, and at the same time, the insulation of the conductive sheet 22 and the top cover sheet 41 is achieved.

The second terminal 21 and the top cover sheet 41 are insulated by a second insulating spacer 27. Among them, rubber, asbestos, etc. can be used as the insulating material.

And correspondingly, as shown in FIG. 2-3, the insulating member 23 is sandwiched between the top cover sheet 41 and the first terminal plate 15, and for this purpose, the insulating member 23 is further provided with the first resistance member 18 through. The hole 231 is configured to achieve conduction between the first resistance member 18 and the top cover sheet 41 and the first terminal plate 15.

As shown in FIG. 4-5, the first terminal 11 includes a terminal body 111 and an extension portion 112. The extension portion 112 extends toward a side of the second terminal 21. The extension portion 112 defines an opening 112a. The outer edge is sealingly connected to the extension portion 112, and the contact piece 12 seals the opening 112a to separate the first chamber S1 from the second chamber S2, and the opening 112a is opposite to the through hole 413 on the top cover sheet 41, The boss 121 is disposed at an intermediate portion of the inverting portion 122 such that when the contact piece 12 operates, the tab 121 passes through the opening 112a And the through hole 413 is in contact with the contact portion 221. The portion for making electrical connection with the pole piece and the outer circuit is located on the terminal body 111, and the extending portion 112 is for connecting with the contact piece 12, which facilitates the arrangement of the contact piece 12 on the first terminal 11.

In the embodiment shown in FIG. 4-5, the terminal body 111 and the extension portion 112 are of a unitary structure. However, it should be noted that in other embodiments, the terminal body 111 and the extension portion 112 may also adopt a split type. Structure, this application does not limit this.

As shown in FIG. 4-5, a columnar body 112b extends from a side of the extending portion 112 toward the top cover sheet 41. The columnar body 112b has a cavity extending along the axial direction thereof, and the cavity extends through the extending portion 112. 112a is formed in the cavity. The inner wall of the columnar body 112b is a stepped structure. The stepped structure forms a stepped surface 112c on the inner wall of the columnar body 112b. The stepped surface 112c is in close contact with the surface of the outer edge of the inverting portion 122. The method of welding or bonding is fixed to achieve a sealed connection.

Further, in order to ensure that the contact piece 12 quickly responds to the internal pressure of the secondary battery, the secondary battery further includes a sealing member 13 sealed between the first chamber S1 and the second chamber S2. According to one embodiment, as shown in FIG. 3, the sealing member 13 is sealingly coupled between the extension portion 112 and the top cover sheet 41, and the sealing member 13 has a first sealing surface 131 in sealing contact with the top cover sheet 41 and the extension portion 112 sealing contact second sealing surface 132.

Specifically, the sealing member 13 is an annular structure, the sealing member 13 is fitted outside the columnar body 112b, and the columnar body 112b is embedded in the through hole 413 together with the sealing member 13, the sealing member 13 and the inner wall of the through hole 413 and the outer wall of the columnar body 112b. The contact is sealed such that the sealing member 13 forms the first sealing surface 131 and the second sealing surface 132 which are disposed opposite each other in the extending direction of the top cover sheet 41.

In addition, as shown in FIG. 7, the sealing member 13 may also be disposed around the through hole 413 and the opening 112a. When the sealing member 13 is in sealing contact with the top cover sheet 41 and the extending portion 112, respectively, the opposite direction is set along the height direction of the secondary battery. The first sealing surface 131 and the second sealing surface 132.

In other embodiments, as shown in FIG. 8, the sealing member 13 may also be sealingly coupled between the contact piece 12 and the top cover sheet 41, and the sealing member 13 has a first sealing surface 131 in sealing contact with the top cover sheet 41 and a second sealing surface 132 in sealing contact with the contact piece 12, and the first sealing surface 131 and the second sealing surface 132 are opposite to each other in the height direction of the secondary battery Settings.

In the embodiment shown in FIG. 8, as long as the top cover sheet 41, the extension portion 112, and the contact piece 12 are slightly modified, the first sealing surface 131 and the second sealing surface 132 may be along the top cover sheet 41. The extending directions are oppositely arranged, and the principle of the sealing structure is basically the same as that of the sealing structure shown in FIG. 3, and details are not described herein again.

In addition, as shown in FIG. 9, a plastic member disposed between the first terminal 11 and the top cover sheet 41 can also be utilized as the sealing member 13, which can reduce the number of components used in the secondary battery and simplify the assembly process. .

As shown in FIG. 2-3, since the space of the second chamber S2 formed by the cover and the cover sheet 41 is limited, the movement space of the contact piece 12 is limited, and in order to increase this space, it is preferable to top. The cover sheet 41 includes a body portion 411 and a raised portion 412 that protrudes toward a side away from the housing such that the second chamber S2 is surrounded by the contact piece 12 and the raised portion 412, and the through hole 413 is disposed in the raised portion 412. In this way, the space of the second chamber S2 is expanded, and the meaning of the expansion of the space is that when the contact piece 12 is operated, the air compression ratio in the space is reduced, and the resistance when the contact piece 12 is operated is reduced. It is beneficial to improve the sensitivity of the contact piece 12 when it is operated.

The application further includes a fuse member 14, as shown in FIG. 1, the fuse member 14 is connected in series through the first pole piece, the first terminal 11, the contact piece 12, the conductive piece 22, the second resistance member 24, the second terminal 21, and the In the electrical connection path of the bipolar piece, and the overcurrent area of the fuse member 14 is smaller than the overcurrent area in the rest of the electrical connection path. Wherein, the fuse member 14 may be connected in series between the first pole piece and the first terminal 11, or the fuse member 14 may be connected in series between the second pole piece and the second terminal 21, or the fuse member 14 may be disposed in two One of them is connected in series between the first pole piece and the first terminal 11, and the other is connected in series between the second pole piece and the second terminal 21. By the arrangement of the fuse member 14, it is possible to fuse at the fuse member 14 by short-circuiting a large current in the electrical connection path, thereby achieving an open circuit between the electrode assembly 31 and the external circuit, reducing the risk of ignition and explosion of the secondary battery.

The fuse member 14 may be provided separately or integrally with other components. In the embodiment shown in FIG. 1, the secondary battery includes a first connecting member 16 and a second connecting member 26, and the first connecting member 16 is connected between the first pole piece and the first terminal 11, and the second connecting member 26 is connected between the second pole piece and the second terminal 21. Wherein the fuse member 14 is formed in the first At least one of the connector 16 and the second connector 26 are on. When the secondary battery is in normal operation, the first connecting member 16 can serve as an electrical connection connecting the first pole piece and the first terminal 11, and the second connecting member 26 serves as an electrical connection connecting the second pole piece and the second terminal 21. The component is beneficial to improve the assembly processability of the secondary battery, and avoids deformation of the first tab 311 and the second tab 312 during the assembly process. However, when the first pole piece and the second pole piece are short-circuited, the fuse member 14 formed on the first connecting piece 16 or the second connecting piece 26 may function as a fuse, and the cutting is formed through the first pole piece and the second pole The circuit of the chip.

The fuse member 14 can be realized by opening a notch or a hole in the first connecting member 16, so that an overcurrent area is formed on the first connecting member 16 smaller than the remaining flow area, and the smaller overcurrent area is Where the fuse member 14 is located.

For the same reason, the above structure can be adopted in the manner of forming the fuse member 14 on the second connecting member 26, and details are not described herein again.

It should be noted that the second resistance member 24 can reduce the short-circuit current at the moment when the contact piece 12 contacts the conductive sheet 22, but the reduced short-circuit current can be sufficient to blow the fuse member 14 to break the electrical connection path.

The first resistance member 18 is intended to reduce the short-circuit current, thereby reducing heat generation due to the inter-pole short circuit inside the secondary battery, and the second resistance member 24 is intended to reduce the peak value of the short-circuit current at the moment of contact between the contact piece 12 and the conductive sheet 22. And the reduced short-circuit current can fuse the fuse member 14 so that the electrical connection path is disconnected, and the overcharge state of the secondary battery is stopped. In view of this, the present application sets the resistance of the first resistance member 18 to be greater than the second resistance. The resistance of the member 24, and the resistance of the first resistance member 18 is at least 1000 times the resistance of the second resistance member 24 to ensure that the first resistance member 18 and the second resistance member 24 serve to improve the safety of the secondary battery. effect.

The above description has been made only for the embodiment in which the first terminal 11 is the positive terminal and the second terminal 21 is the negative terminal. However, the present application is not limited to the above embodiment, and for example, the first terminal 11 may be used as the negative electrode. The terminal, correspondingly, uses the second terminal 21 as a positive terminal or the like.

Moreover, those skilled in the art should understand that depending on the position of the contact piece 12 and the conductive member 22, correspondingly, the structure and arrangement of each component in the secondary battery can be variously modified.

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 secondary battery comprising: an electrode assembly, first and second terminals, and a top cover sheet, wherein

The electrode assembly includes a first pole piece, a second pole piece, and a partition disposed between the first pole piece and the second pole piece, the first terminal being electrically connected to the first pole piece The second terminal is electrically connected to the second pole piece,

The secondary battery further includes: a first resistance member, a second resistance member, a contact piece attached to the first terminal, and a conductive piece electrically connected to the second terminal,

The top cover sheet is always electrically connected to the first terminal through the first resistance member, and the top cover sheet is insulated from the second terminal and the conductive sheet,

And when the internal pressure of the secondary battery exceeds a reference pressure, the contact piece acts under the action of air pressure and contacts the conductive sheet to form through the first pole piece, the first terminal, the Electrical connection paths of the contact piece, the conductive sheet, the second terminal, and the second pole piece,

The second resistance member is connected in series in the electrical connection path, and the resistance of the first resistance member is greater than the resistance of the second resistance member.
A secondary battery according to claim 1, further comprising a housing, said top cover sheet being covered with said housing to form a first chamber for encapsulating said electrode assembly and for said contact a second chamber providing an action space,

The first chamber and the second chamber are separated by the contact piece, and the conductive sheet is located on a side of the top cover sheet away from the electrode assembly.
The secondary battery according to claim 2, wherein said top cover sheet is provided with a through hole, and said conductive sheet has a contact portion capable of coming into contact with said contact piece after the action, said contact portion being located at said Said in the second chamber.
The secondary battery according to claim 3, wherein said top cover sheet comprises a body portion and a raised portion, said raised portion protruding toward a side away from said housing, said second chamber being The contact piece is enclosed with the raised portion, and the through hole is disposed on the raised portion.
The secondary battery according to claim 3, wherein said first end The sub-assembly includes a connected terminal body and an extension,

An opening is formed in the extension, the opening is opposite to the through hole, and the contact piece seals the opening to separate the first chamber from the second chamber.
The secondary battery according to claim 5, wherein the terminal body and the extension portion are of a unitary structure or a split structure.
The secondary battery according to claim 5, further comprising a sealing member sealed between the first chamber and the second chamber, the sealing member being sealingly coupled to the extension and Between the top cover sheets, and having a first sealing surface in sealing contact with the top cover sheet and a second sealing surface in sealing contact with the extension portion.
The secondary battery according to claim 2, further comprising a sealing member sealed between said first chamber and said second chamber, said sealing member being sealed to said contact piece and said Between the top cover sheets, and having a first sealing surface in sealing contact with the top cover sheet and a second sealing surface in sealing contact with the contact sheet.
The secondary battery according to claim 7 or 8, wherein the first sealing surface and the second sealing surface are disposed opposite to each other in the extending direction of the top cover sheet, and/or

The first sealing surface and the second sealing surface are disposed opposite to each other in a height direction of the secondary battery.
The secondary battery according to claim 5, wherein said contact piece comprises a reversing portion and a projection.

The turning portion is a sheet-shaped torus structure,

The protrusion is coupled to the inversion portion and protrudes toward a side of the top cover sheet,

An outer edge of the inversion portion is sealingly coupled to the extension portion, and the contact piece is in contact with the contact portion through the protrusion when the contact piece is inverted.
The secondary battery according to claim 1, further comprising a first terminal plate, said first terminal being electrically connected to said first terminal plate, said first resistance member being connected in series to said first terminal Between the plate and the top cover sheet.
The secondary battery according to claim 11, wherein said first resistance member has a first end and a second end,

a first recess is formed on the top cover sheet, and the first end is embedded in the first recess Inside,

and / or

A second recess is formed on the first terminal plate, and the second end is embedded in the second recess.
The secondary battery according to claim 1, further comprising a second terminal plate, said second terminal being electrically connected to said second terminal plate, said second resistance member being connected in series to said second terminal Between the plate and the conductive sheet.
The secondary battery according to claim 1, wherein the resistance of the first resistance member is at least 1000 times the resistance of the second resistance member.
The secondary battery according to claim 14, wherein the resistance value of the first resistance member ranges from 1 ohm to 100,000 ohms.

The resistance value of the second resistance member ranges from 0.1 milliohm to 100 milliohms.
The secondary battery according to any one of claims 1 to 10, further comprising a fuse member, the fuse member being connected in series through the first pole piece, the first terminal, In the electrical connection path of the contact piece, the conductive piece, the second terminal and the second pole piece, an overcurrent area at the fuse member is smaller than a flow area at a remaining portion of the electrical connection path; and

The fuse member is connected in series between the first pole piece and the first terminal, and/or

The fuse member is connected in series between the second pole piece and the second terminal.
The secondary battery according to claim 16, further comprising a first connecting member and a second connecting member,

The first pole piece is electrically connected to the first terminal through the first connecting member, and the second pole piece is electrically connected to the second terminal through the second connecting piece,

The fuse member is formed on the first connecting member and/or the second connecting member.
The secondary battery according to claim 17, wherein the fuse member is formed by opening a notch and/or a hole on the first connecting member and/or the second connecting member.