A secondary battery connection piece and a secondary battery

Abstract

The present invention discloses a connecting piece for a secondary battery, which includes a pole connection section, an ear connection section, an external short-circuit connection section, a first bending section, a second bending section, and an overcurrent fusing protection part; the pole connection section is adjacent to and separated from the external short-circuit connection section and is connected to the ear connection section; the first bending section is arranged between the pole connection section and the ear connection section, the second bending section is arranged between the external short-circuit connection section and the ear connection section, and the overcurrent fusing protection part is arranged on the first bending section or the second bending section. The present invention provides a connecting piece for a secondary battery, which can not only ensure effective fusing under high current conditions of the battery to avoid safety hazards such as high temperature rise caused by high current inside the battery, but also effectively connect the external short-circuit connection device before the internal temperature of the battery continues to rise and thermal runaway is about to occur, reducing the harm caused by thermal runaway.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and particularly relates to a connecting piece for a secondary battery and a secondary battery. Background Art

[0002] Lithium-ion batteries are widely used in consumer electronics, new energy vehicles, energy storage and other fields due to advantages such as high energy density and long cycle life. With the popularization of new energy products, the safety performance of batteries has received extensive attention. Therefore, it is urgent to solve safety problems such as overcharge testing, external short-circuit testing and thermal runaway testing of batteries, which creates many difficulties for the design and manufacture of batteries.

[0003] The overcharge protection and external short-circuit protection designs of batteries are particularly important for the application of batteries, and the overcurrent fusing protection design of tab connecting pieces is often applied; however, for another safety performance test, that is, the thermal runaway test, the safety design used is mainly the external short-circuit design. There is a problem of incompatibility between the external short-circuit protection design and the external short-circuit connection design. How to achieve external short-circuit protection and overcharge protection mainly based on overcurrent fusing protection while also taking into account the design of external short-circuit connection has become a difficult problem. Summary of the Invention

[0004] In order to solve the deficiencies of the existing technology described above, the present invention provides a connecting piece for a secondary battery, which can not only ensure effective fusing of the battery under high current conditions, avoid safety hazards such as high temperature rise caused by high current inside the battery; but also effectively connect the external short-circuit connection device before the temperature inside the battery continues to rise and thermal runaway is about to occur, reducing the harm caused by thermal runaway; the secondary battery prepared from this connecting piece can simultaneously be compatible with the functions of overcurrent fusing protection and external short-circuit connection design, improving the overall safety performance of the secondary battery.

[0005] The technical effects to be achieved by the present invention are realized through the following solutions:

[0006] The connecting piece for a secondary battery in the present invention includes a connecting piece body, and the connecting piece body includes a pole connection section, a tab connection section, an external short-circuit connection section, a first bending section, a second bending section and an overcurrent fusing protection part; the pole connection section is adjacent to and separated from the external short-circuit connection section and is connected to the tab connection section; the first bending section is arranged between the pole connection section and the tab connection section, the second bending section is arranged between the external short-circuit connection section and the tab connection section, and the overcurrent fusing protection part is arranged on the first bending section or the second bending section.

[0007] The connecting piece body is used for the conductive connection of the first pole column and the second pole column. The pole column connecting section is used for connecting and conducting electricity with the first pole column. The tab connecting section is used for connecting and conducting electricity with the tab of the battery cell. The external short-circuit connecting section is used for connecting with the external short-circuit connecting device. When the temperature inside the battery continues to rise and thermal runaway is about to occur, the external short-circuit connecting device can be effectively triggered to reduce the harm caused by thermal runaway. The first bending section and the second bending section are used to adapt the overall connecting piece body to the installation of the secondary battery top cover and the battery cell. The overcurrent fusing protection part can be effectively fused under the condition of large current in the battery, avoiding safety hazards such as temperature rise caused by large current inside the battery.

[0008] Further, the overcurrent fusing protection part is in the structure of a fuse hole, a fuse cavity, a fusible link or a fusible sheet. When the battery is short-circuited, a very large current is generated instantaneously in the whole circuit. Since the overcurrent area of the fuse hole and fuse cavity regions is small and the resistance is large, high-temperature fusing occurs first, thus playing a role in protecting the circuit. When the battery is short-circuited, a very large current is generated instantaneously in the whole circuit. High-temperature fusing occurs first in the regions of the fusible link and fusible sheet, playing a role in protecting the circuit.

[0009] Further, the first bending section and the second bending section are not directly connected, which can ensure the effectiveness of protecting the circuit after the overcurrent fusing protection part is fused at high temperature.

[0010] To further optimize the structure, the end face of the tab connecting section is an arc surface.

[0011] Further, the connecting piece body is integrally formed by an aluminum sheet or a copper sheet, which not only has good electrical conductivity and ductility, but also has good thermal conductivity.

[0012] A secondary battery includes a housing, a battery cell, a secondary battery top cover and the secondary battery connecting piece described in any one of the above. The housing and the secondary battery top cover are used for the installation, fixation and protection of the battery cell. The battery cell is arranged inside the housing. The secondary battery top cover is hermetically installed on the housing. The secondary battery connecting piece is arranged between the secondary battery top cover and the battery cell, and the tab connecting section is electrically connected to the tab of the battery cell.

[0013] Further, the top cover of the secondary battery includes a top cover sheet, a first pole column, a second pole column, and an external short-circuit connection device; the first pole column and the second pole column are provided at both ends of the top cover sheet; the first pole column is electrically connected to the pole column connection section and is separated and insulated from the top cover sheet by a first insulating member, and the second pole column is electrically connected to the top cover sheet; the external short-circuit connection device is provided on the top cover sheet, is electrically connected to the external short-circuit connection section, and is separated and insulated from the top cover sheet and the first pole column by a second insulating member, and is electrically connected to the second pole column through a conductive sheet. A circuit structure in which a first pole column - pole column connection section - tab connection section - external short-circuit connection section - external short-circuit connection device - conductive sheet - second pole column are sequentially electrically connected is formed inside the secondary battery.

[0014] The top cover sheet is used for the installation and fixation of the pole column, explosion-proof valve, and external short-circuit connection device, and is simultaneously sealed and installed on the battery case for the overall installation and sealing of the battery; the first pole column and the second pole column are used for the conduction and connection between the internal battery cells and the external circuit; the external short-circuit connection device is used to connect the positive and negative electrodes of the battery cells, causing the battery to short-circuit and avoiding the phenomenon of thermal runaway caused by the continued operation of the battery.

[0015] Under normal temperature or when the triggering condition is not reached, the external short-circuit connection device is in an open state, that is, the connection piece body is separated and insulated from the second pole column; and in the open state of the external short-circuit connection device, it does not affect the relevant electrical properties during the normal use process of the battery cells, does not increase the internal resistance value of the battery cells, and does not occupy the effective space of the safety explosion-proof valve.

[0016] Under normal temperature or when the triggering condition is not reached, the external short-circuit connection device is in an open state. If an electrical connection occurs between the first pole column and the second pole column of the battery cells, that is, an external short circuit, the overcurrent fusing protection part of the connection piece body will fuse. At this time, the tab connection section is separated and insulated from the first pole column, which can avoid the occurrence of an external short circuit between the first pole column and the second pole column, resulting in temperature rise, or even hazards such as fire and explosion.

[0017] Under high temperature or when the triggering condition is reached, the external short-circuit connection device is in a conducting state, that is, the connection piece body is electrically connected to the second pole column; when the battery cells are in a high-temperature state, or due to various reasons, internal self-heating occurs, or even an internal short circuit occurs, a large amount of heat will be generated, ultimately leading to the fire and explosion of the battery cells. The conduction temperature of the external short-circuit connection device needs to be lower than the temperature at which thermal runaway is triggered. When the temperature rises to the conduction temperature value of the external short-circuit connection device and the internal short circuit has not been triggered, the external short-circuit connection device is triggered to conduct. Since the temperature rise caused by the external short circuit is less than the temperature rise caused by the internal short circuit, this device can reduce the hazards caused by the thermal runaway of the battery cells.

[0018] Further, the connection methods of the secondary battery connection piece with the battery cells, the first pole column, and the external short-circuit connection device are preferably laser welding and ultrasonic welding.

[0019] To further optimize the structure, the external short-circuit connection device is an NTC high-temperature connection device or a high-temperature deformation conduction device.

[0020] Furthermore, the top cover of the secondary battery further includes an explosion-proof valve and a liquid injection hole. The explosion-proof valve is provided in the middle of the top cover sheet, and the liquid injection hole is provided between the explosion-proof valve and the first pole column or the second pole column. The explosion-proof valve is used for pressure relief inside the battery, and the liquid injection hole is used for injecting electrolyte into the battery case.

[0021] The present invention has the following advantages:

[0022] The present invention provides a connection piece for a secondary battery, which can not only ensure effective fusing of the battery under high current conditions, avoid safety hazards such as high temperature rise caused by high current inside the battery, but also effectively connect the external short-circuit connection device when the temperature inside the battery continues to rise and thermal runaway is about to occur, reducing the harm caused by thermal runaway. The secondary battery prepared from this connection piece can simultaneously be compatible with overcurrent fusing protection and external short-circuit connection design functions, improving the overall safety performance of the secondary battery. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of the straight state of the connection piece for a secondary battery in the present invention;

[0024] Figure 2 It is a schematic cross-sectional structural diagram of the top cover of the secondary battery and the connection piece for the secondary battery in the present invention;

[0025] Figure 3 It is a schematic side view of the connection between the top cover of the secondary battery, the connection piece for the secondary battery and the battery cell;

[0026] Figure 4 It is a schematic diagram of the connection between the inner side of the top cover of the secondary battery, the pole ear of the battery cell and the connection piece for the secondary battery in the present invention.

[0027] The description of the reference numerals in the drawings is as follows:

[0028] 10. Connection piece body; 101. Pole column connection section; 102. External short-circuit connection section; 103. Pole ear connection section; 104. First bending section; 105. Second bending section; 106. Overcurrent fusing protection part; 20. Top cover of secondary battery; 201. Top cover sheet; 202. First pole column; 203. Second pole column; 204. First insulating part; 205. External short-circuit connection device; 206. Conductive sheet; 207. Second insulating part; 208. Explosion-proof valve; 209. Liquid injection hole; 30. Battery cell; 301 / 302. Pole ear. Detailed Embodiment

[0029] The present invention will be described in detail below with reference to the drawings and embodiments.

[0030] The secondary battery connection tab in the embodiments of the present invention is as shown in the attached Figure 1 figure, and includes a connection tab body 10. The connection tab body includes a pole connection section 101, an ear connection section 103, an external short - circuit connection section 102, a first bending section 104, a second bending section 105, and an over - current fusing protection part 106. The pole connection section is adjacent to and separated from the external short - circuit connection section, and is connected to the ear connection section. The first bending section is arranged between the pole connection section and the ear connection section, the second bending section is arranged between the external short - circuit connection section and the ear connection section, and the over - current fusing protection part is arranged on the first bending section or the second bending section.

[0031] The over - current fusing protection part 106 is in the structure of an insurance hole, an insurance cavity, a fusible strip or a fusible sheet. When the battery is short - circuited, a large current is instantaneously generated in the whole circuit. Since the over - current area of the insurance hole and insurance cavity regions is small and the resistance is large, high - temperature fusing occurs first, thus playing a role in protecting the circuit. When the battery is short - circuited, a large current is instantaneously generated in the whole circuit, and high - temperature fusing occurs first in the regions of the fusible strip and fusible sheet, playing a role in protecting the circuit. The first bending section 104 and the second bending section 105 are not directly connected, which can ensure the effectiveness of protecting the circuit after the over - current fusing protection part is high - temperature fused. To further optimize the structure, the end face of the ear connection section 103 is an arc surface, which can be adapted to the explosion - proof valve. The connection tab body 10 is integrally formed by an aluminum sheet or a copper sheet, which not only has good electrical conductivity and ductility, but also has good thermal conductivity.

[0032] The secondary battery in the embodiments of the present invention is as shown in the attached Figures 2 - 4 figure, and includes a housing (not marked in the figure), an electric core 30, a secondary battery top cover 20, and the above - mentioned secondary battery connection tab. The housing and the secondary battery top cover are used for the installation, fixation and protection of the electric core. The electric core is arranged inside the housing, the secondary battery top cover is hermetically installed on the housing, and the secondary battery connection tab is arranged between the secondary battery top cover and the electric core, and the ear connection section 103 is electrically connected to the ear 301 of the electric core.

[0033] The secondary battery top cover includes a top cover sheet 201, a first pole 202, a second pole 203, and an external short - circuit connection device 205. The first pole and the second pole are arranged at both ends of the top cover sheet. The first pole is electrically connected to the pole connection section 101 and is separated and insulated from the top cover sheet by a first insulating member 204. The second pole is electrically connected to the top cover sheet. The external short - circuit connection device is arranged on the top cover sheet, is electrically connected to the external short - circuit connection section 102, and is separated and insulated from the top cover sheet and the first pole by a second insulating member 207, and is electrically connected to the second pole through a conductive sheet 206. A circuit structure in which the first pole - pole connection section - ear connection section - external short - circuit connection section - external short - circuit connection device - conductive sheet - second pole are electrically connected in sequence is formed inside the secondary battery.

[0034] The top cover sheet is used for the installation and fixation of the pole post, explosion-proof valve and external short-circuit connection device, and is also hermetically installed on the battery case for the overall installation and sealing of the battery; the first pole post and the second pole post are electrically connected to the pole tabs 301 / 302 of the battery cell respectively for conducting electricity between the battery cell inside the battery and the external circuit; the external short-circuit connection device is used to connect the positive and negative electrodes of the battery cell to cause the battery to short-circuit and avoid the phenomenon of thermal runaway caused by the continuous operation of the battery. The connection sheet body is used for the conductive connection between the first pole post and the second pole post. The pole post connection section is used to connect and conduct electricity with the first pole post. The pole tab connection section is used to connect and conduct electricity with the pole tab of the battery cell. The external short-circuit connection section is used to connect with the external short-circuit connection device. When the temperature inside the battery continues to rise and is about to undergo thermal runaway, the external short-circuit connection device is effectively triggered to reduce the harm caused by thermal runaway; the first bending section and the second bending section are used to adapt to the installation of the connection sheet body as a whole with the top cover of the secondary battery and the battery cell. The overcurrent fusing protection section is used to effectively fuse the battery under the condition of large current to avoid safety hazards such as temperature rise caused by large current inside the battery.

[0035] The connection methods of the secondary battery connection sheet with the battery cell 30, the first pole post 202 and the external short-circuit connection device 205 are preferably laser welding and ultrasonic welding. To further optimize the structure, the external short-circuit connection device 205 is an NTC high-temperature connection device or a high-temperature deformation conduction device. The secondary battery top cover further includes an explosion-proof valve 208 and a liquid injection hole 209. The explosion-proof valve is arranged in the middle of the top cover sheet, and the liquid injection hole is arranged between the explosion-proof valve and the first pole post or the second pole post. The explosion-proof valve is used for pressure relief inside the battery, and the liquid injection hole is used for injecting electrolyte into the battery case.

[0036] The secondary battery connection sheet and the secondary battery in the embodiments of the present invention can simultaneously be compatible with the design functions of overcurrent fusing protection and external short-circuit connection. The external short-circuit connection device is an NTC high-temperature connection device or a high-temperature deformation conduction device. Under normal temperature or when the triggering condition is not reached, it is in a disconnected state, that is, the connection sheet body 10 is separated and insulated from the second pole post 203; and in the disconnected state of the external short-circuit connection device, it does not affect the relevant electrical properties during the normal use process of the battery cell, does not increase the internal resistance value of the battery cell, and does not occupy the effective space of the safety explosion-proof valve.

[0037] Under normal temperature or when the triggering condition is not reached, the external short-circuit connection device is in a disconnected state. If an electrical connection occurs between the first pole post and the second pole post of the battery cell, that is, an external short circuit, the overcurrent fusing protection section 106 of the connection sheet body 10 will fuse. At this time, the pole tab connection section 103 is separated and insulated from the first pole post 202, which can avoid the external short circuit between the first pole post and the second pole post, resulting in temperature rise, or even fire and explosion and other hazards.

[0038] The external short-circuit connection device is in a conducting state under high temperature or when the triggering condition is met, that is, the connecting piece body 10 is electrically connected to the second pole column 203; when the battery cell is in a high-temperature state, or due to various reasons, internal self-heating occurs, and even in the case of internal short circuit, a large amount of heat will be generated, ultimately leading to the battery cell catching fire and exploding. The conduction temperature of the external short-circuit connection device needs to be lower than the temperature at which thermal runaway is triggered. When the temperature rises to the conduction temperature value of the external short-circuit connection device and internal short circuit has not been triggered, the external short-circuit connection device is triggered to conduct. Since the temperature rise caused by external short circuit is less than that caused by internal short circuit, this device can reduce the harm caused by the thermal runaway of the battery cell.

[0039] As can be seen from the solutions of the above embodiments, the present invention provides a connecting piece for a secondary battery, which can not only ensure that the battery effectively melts under high current conditions, avoid safety hazards such as high temperature rise caused by high current inside the battery, but also effectively connect the external short-circuit connection device before thermal runaway occurs when the temperature inside the battery continues to rise, reducing the harm caused by thermal runaway; the secondary battery prepared from this connecting piece can simultaneously be compatible with over-current fusing protection and external short-circuit connection design functions, improving the overall safety performance of the secondary battery.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention and are not intended to limit them. Although the embodiments of the present invention have been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the embodiments of the present invention can still be modified or equivalently replaced, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A secondary battery connecting piece, comprising a connecting piece body, characterized in that: The connection piece body includes a pole connection section, an ear connection section, an external short-circuit connection section, a first bending section, a second bending section, and an overcurrent fusing protection part; The pole connection section is adjacent to and separated from the external short-circuit connection section and is connected to the ear connection section; The first bending section is arranged between the pole connection section and the ear connection section, the second bending section is arranged between the external short-circuit connection section and the ear connection section, and the overcurrent fusing protection part is arranged on the first bending section or the second bending section; The overcurrent fusing protection part is in the structure of an insurance hole, an insurance cavity, a fusible strip, or a fusible sheet; The first bending section and the second bending section are not directly connected.

2. The secondary battery connecting piece according to claim 1, characterized in that: The end face of the ear connection section is an arc surface.

3. The secondary battery connection piece according to claim 1, characterized in that: The connection piece body is integrally formed from an aluminum sheet or a copper sheet.

4. A secondary battery, characterized in that: It includes a housing, an electric core, a secondary battery top cover, and the secondary battery connection piece according to any one of claims 1-3; The electric core is arranged inside the housing, the secondary battery top cover is sealed and installed on the housing, the secondary battery connection piece is arranged between the secondary battery top cover and the electric core, and the ear connection section is electrically connected to the ear of the electric core.

5. The secondary battery according to claim 4, wherein: The secondary battery top cover includes a top cover sheet, a first pole, a second pole, and an external short-circuit connection device; The first pole and the second pole are arranged at both ends of the top cover sheet; the first pole is electrically connected to the pole connection section and is insulated from the top cover sheet through a first insulating member, and the second pole is electrically connected to the top cover sheet; The external short-circuit connection device is arranged on the top cover sheet, is electrically connected to the external short-circuit connection section, and is insulated from the top cover sheet and the first pole through a second insulating member and is electrically connected to the second pole through a conductive sheet.

6. The secondary battery according to claim 5, wherein: The connection mode of the secondary battery connection piece with the electric core, the first pole, and the external short-circuit connection device is laser welding or ultrasonic welding.

7. The secondary battery according to claim 5, wherein: The external short-circuit connection device is an NTC high-temperature connection device or a high-temperature deformation conduction device.

8. The secondary battery according to claim 5, characterized in that: The secondary battery top cover further includes an explosion-proof valve and a liquid injection hole. The explosion-proof valve is arranged in the middle of the top cover sheet, and the liquid injection hole is arranged between the explosion-proof valve and the first pole or the second pole.

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