CN205542925U - Secondary cell and top cap thereof - Google Patents

Abstract

The utility model discloses a secondary battery and its top cover. The top cover includes a conductive top cover sheet, a conductive flip sheet, a conductive boss, a temperature deformation member, a first pole and a second pole; the first pole and the second pole pass through the conductive top cover respectively, And the first pole is electrically insulated from the conductive top cover, the second pole is electrically connected to the conductive top cover; the conductive flip piece is electrically connected to the first pole, and is electrically insulated from the conductive top cover; the conductive boss is installed on the The bottom of the conductive flip sheet is electrically connected to the second pole through the conductive top cover sheet; the conductive flip sheet is insulated from each other due to the gap between the conductive boss and the conductive boss, but has a tendency to turn over towards the conductive boss; the temperature deformation part resists Withstand the conductive flip sheet and counter its flipping tendency, making the conductive flip sheet unable to flip at normal temperature. The utility model uses the temperature deformable part as the starting element of the outer short connection device, so the outer short of the secondary battery can be quickly and reliably realized when the temperature rises, and the thermal runaway of the battery core can be effectively avoided.

Description

Secondary battery and its top cover

technical field

The utility model belongs to the technical field of secondary batteries, in particular to a secondary battery and its top cover which can effectively prevent the battery core from overheating and out of control.

Background technique

Lithium-ion secondary batteries have been widely used in hybrid and electric vehicles due to their high energy, high capacity, and high power. For lithium-ion secondary batteries used as automotive power sources, safety is the top priority, and the overcharge test is one of the three most extreme tests that must pass.

At present, most of the overcharge tests of lithium-ion secondary batteries use the principle of external short circuit to ensure safety, that is, the external short connection device is used to perform external short circuit before the battery cell goes out of control, so as to avoid the rapid heat generation inside the battery cell and lead to runaway. Existing external short-circuit connection devices all reach a certain air pressure after the gas is produced inside the battery cell, so that the short-circuit device is activated to form a short-circuit circuit. However, since the corresponding relationship between the SOC (state of charge, indicating the ratio of the charging capacity and the rated capacity) and the gas production of the battery before the battery is overcharged and out of control is not completely determined, the external short connection device that uses the air pressure as the starting condition is reliable. If the safety is not high enough, it is easy to cause the battery cell to be overcharged and out of control while the outer short connection device has not started to work, which will eventually lead to a safety accident of the battery cell.

In view of this, it is indeed necessary to provide a secondary battery and its top cover with higher reliability.

Utility model content

The purpose of the utility model is to provide a secondary battery with higher reliability and its top cover, so as to effectively prevent the battery cell from being overcharged and out of control.

In order to achieve the above purpose, the inventors of the utility model have found through research that before the battery is overcharged and out of control, the corresponding relationship between the SOC and the surface temperature of the battery is relatively definite. Therefore, it is more reliable to use the temperature deformation part as the starting element of the outer short connection device To prevent battery safety problems caused by overcharging.

Accordingly, the utility model provides a secondary battery top cover, which includes a conductive top cover sheet, a conductive flip sheet, a conductive boss, a temperature deformable part, a first pole and a second pole;

The first pole and the second pole respectively pass through the conductive top cover, and the first pole is electrically insulated from the conductive top cover, and the second pole is electrically connected to the conductive top cover;

The conductive overturning piece is electrically connected to the first pole and electrically insulated from the conductive top cover; the conductive boss is installed under the conductive overturning piece and is electrically connected to the second pole through the conductive top cover; There is a gap between the bosses to insulate each other, but there is a tendency to turn over towards the conductive boss;

The temperature deformable part is arranged under the conductive reversing sheet, which resists the conductive reversing sheet and competes with the reversing tendency of the conductive reversing sheet, so that the conductive reversing sheet cannot be turned at room temperature;

When the temperature rise causes the temperature of the temperature-deformed part to reach or exceed its deformation temperature, the temperature-deformed part will undergo memory deformation and no longer touch the conductive flipping piece, and the conductive flipping piece will turn over under the action of the flipping trend and be electrically connected to the conductive boss , so that the first pole and the second pole are electrically connected.

As an improvement on the top cover of the secondary battery of the present invention, the conductive turning piece includes a pole connecting piece and a turning connecting piece; the pole connecting piece covers the outer peripheral wall of the first pole and is electrically connected to the first pole ; The overturning connecting piece is a conductive piece that can be actively deformed or deformed by force, one end of which is electrically connected to the pole connecting piece, and the other end is a floating end and has a turning tendency to approach the conductive boss.

As an improvement on the top cover of the secondary battery of the present invention, it also includes an insulator fixed on the conductive top cover sheet, the insulator is installed between the conductive flip sheet and the conductive top cover sheet, and the conductive flip sheet is placed above it. A support is formed to avoid contact between the overturned connecting piece and the conductive top cover; the temperature deformation member is installed between the overturned connecting piece and the insulator, one end is fixed on the insulator, and the free end is tilted up to withstand the overturned connecting piece.

As an improvement on the top cover of the secondary battery of the present invention, the flip connecting piece is made of elastically deformable material, and when it is in a natural state, the suspended end contacts the conductive boss; The connecting piece is elastically deformed, and the suspended end is upturned to be separated and insulated from the conductive boss.

As an improvement on the top cover of the secondary battery of the present invention, the turning tendency of the turning connecting piece to the conductive boss is provided by a spring in a stretched state; On the platform, the upper end pulls the floating end of the flip connecting piece so that it has a flipping tendency to approach the conductive boss; the spring is an insulating spring or at least one end is provided with an insulating structure to ensure that the secondary battery will not be damaged due to the existence of the spring. External short circuit at room temperature.

As an improvement on the top cover of the secondary battery of the present invention, the conductive boss includes a sheet-shaped positioning part and a raised part protruding upward from the positioning part; the positioning part is fixed on the conductive top cover sheet below the flip connecting piece and It is electrically connected with the conductive top cover sheet, and the raised part is aligned with the floating end of the turning connection sheet.

As an improvement on the top cover of the secondary battery of the present invention, the contact surface of the floating end of the flip connecting piece and the raised portion of the conductive boss is set in a shape corresponding to each other.

As an improvement on the top cover of the secondary battery of the present invention, the floating end of the flip connecting piece is provided with a small protrusion facing the raised part, and the top of the raised part of the conductive boss is provided with a the groove; when the turning connecting piece is flipped to the conductive boss, the small protrusion is inserted into the groove.

As an improvement on the top cover of the secondary battery of the present invention, at least one of the floating end of the flip connecting piece and the raised portion of the conductive boss is provided with a magnet, and the other is provided with a magnetic adsorption body, and the flip connecting piece is provided with a magnetic force. Provides a tendency to overturn and makes the overturned dangling end and the raised part tightly contact.

In order to achieve the above object, the utility model also provides a secondary battery, which includes a casing, a cell, and a top cover of the secondary battery; the cell is accommodated in the casing, and the top cover is installed on the casing; the The secondary battery top cover is the secondary battery top cover described in any of the above paragraphs

Compared with the prior art, the utility model is based on the deformation characteristics of the temperature deformable part at different temperatures, and uses the temperature deformable part as the starting element of the outer short connection device, so it can quickly and reliably realize two The external short circuit of the secondary battery effectively avoids the occurrence of overcharging and out of control of the battery cell, ensuring the safety of the battery cell.

Description of drawings

The secondary battery, top cover and beneficial technical effects of the utility model will be described in detail below in conjunction with the accompanying drawings and specific embodiments, wherein:

Fig. 1 is the structural representation of the utility model secondary battery top cover;

Figure 2 is a schematic cross-sectional view of Figure 1;

FIG. 3 is an enlarged view of part A in FIG. 2 .

detailed description

In order to make the purpose, technical solution and beneficial technical effects of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific implementations described in this specification are only for explaining the utility model, not for limiting the utility model.

Please refer to Fig. 1 to Fig. 3, the secondary battery of the present utility model comprises housing (not shown in figure), cell (not shown in figure) and top cover, and top cover comprises conductive top cover sheet 20, first pole 22, the second Diode post 24 and outer short connection device 30 . Wherein, the electric core is accommodated in the casing, and the conductive top cover sheet 20 is installed on the casing to seal the electric core. The lower parts of the first pole 22 and the second pole 24 are respectively electrically connected with the positive or negative poles of the electric core in the housing (there is no fixed requirement for the positive and negative polarities of the two poles, and the poles with opposite polarities are connected respectively. That is), the top passes through the conductive top cover sheet 20; the first pole 22 is electrically insulated from the conductive top cover sheet 20, and the second pole 24 is electrically connected to the conductive top cover sheet 20. The conductive top cover sheet 20 is also provided with a liquid injection hole 25 for injecting electrolyte into the housing. The outer short connection device 30 is provided on the side of the conductive top cover sheet 20 away from the battery cell, and is used to perform an external short circuit on the secondary battery to ensure its safety when the battery temperature rises to a predetermined level.

The outer short connection device 30 includes a conductive turning piece 40 , an insulating piece 42 , a temperature deformation piece 44 and a conductive boss 46 . The conductive flip 40 is electrically connected to the first pole 22, and is insulated from the conductive top cover 20 by an insulator 42; the conductive boss 46 is installed on the conductive top cover 20 and connected to the second pole by the conductive top cover 20. The post 24 is electrically connected; the conductive reversing sheet 40 is insulated from each other due to the gap between the conductive boss 46, but it has a tendency to turn over to the conductive boss 46; the temperature deformation part 44 is installed on the insulating member 42 or the conductive top cover sheet 20, it resists the conductive flip 40 and competes with the flip tendency of the conductive flip 40, so that the conductive flip 40 cannot flip at normal temperature.

The conductive turning piece 40 includes a pole connecting piece 400 and a turning connecting piece 402 . The pole connection piece 400 is installed on the outside of the conductive top cover piece 20, and it covers the outer peripheral wall of the first pole 22 and is electrically connected with the first pole 22; One end of the sheet is electrically connected to the pole connection sheet 400 , and the other end is a floating end and has a tendency to turn over towards the conductive boss 46 on the conductive top cover sheet 20 . The pole connection piece 400 and the flip connection piece 402 can be two independent components as shown in FIG. 3 , or can be integrally formed as one component.

The insulator 42 is installed between the conductive overturning piece 40 and the conductive top cover piece 20, its lower part is fixed on the conductive top cover piece 20 by welding, riveting, mechanical fit, glue joint or other suitable methods, and the upper part is fixed on the conductive overturning piece 20. 40 forms a support to prevent it from contacting the conductive cap sheet 20 . A protrusion 420 is provided on the upper surface of the insulator 42 , and a perforation corresponding to the protrusion 420 is provided on the conductive flipping piece 40 , and the positioning of the flipping connecting piece 402 is realized by cooperation of the protrusion 420 and the perforation. Specifically: when the pole connection piece 400 and the flip connection piece 402 are two components, both of them have perforations corresponding to the protrusions 420, and the pole connection piece 400 is on the top and the flip connection piece 402 is on the bottom. It is connected with the insulator 42; when the pole connection piece 400 and the flip connection piece 402 belong to the same component, it is only necessary to open a perforation for the two to realize positioning.

The temperature deformable part 44 is made of shape memory material, which has different shapes at room temperature and high temperature, therefore, when the temperature reaches or exceeds the deformation temperature of the shape memory material, the shape memory material will change from normal temperature form to high temperature form. The temperature deformation member 44 can be made of at least two kinds of Au, Ag, Cd, Cu, Zn, Al, Sn, Si, Ga, In, Ti, Ni, Fe, Pt, Pd, Nb, Fe, Mn, Ce, Br, etc. Elemental alloys or polymer materials that have a memory effect on temperature, for example, the temperature deformable part 44 is made of CeBr ₃ . The deformation temperature of the temperature deformation member 44 of the present invention is 65-100°C, preferably 80°C.

The temperature deformation member 44 is installed between the flip connecting piece 402 and the insulating member 42, and it is in an elastic pre-deformation state at room temperature, and will return to a natural state under the action of restoring force at high temperature, that is to say, memory deformation occurs. At room temperature, one end of the temperature-deformable member 44 is fixed on the insulating member 42, and the free end lifts up and bears against the overturning connecting piece 402. Cannot be flipped. When the temperature of the battery cell increases due to overcharging or other reasons in the secondary battery, the first pole 22, the second pole 24, the conductive top cover 20, the conductive boss 46, and the conductive flipping piece electrically connected to the battery 40 and temperature deformable parts 44 and other components will rise in temperature. When the temperature of temperature deformable parts 44 rises to reach or exceed its deformation temperature, temperature deformable parts 44 will undergo memory deformation and will no longer touch against and turn over connecting piece 402 , the overturned connecting piece 402 is overturned due to the loss of abutment, and is electrically connected to the conductive boss 46 on the conductive top cover piece 20 after being overturned. The fixing of the temperature deforming member 44 on the insulating member 42 can be realized in various suitable ways, preferably by covering the protrusion 420 through the opened perforation, and pressing and fixing it by the pole connecting piece 400 and/or the turning connecting piece 402 . The utility model does not directly use the shape memory material to make the flip connecting piece that can be turned over by itself at high temperature, but makes it into a temperature deformable part 44 as a support element for the flip connecting piece 402 at normal temperature. One of the reasons is that the flip connecting piece must It has good conductivity, large enough overturn deformation and low cost, but there are not many types of shape memory materials that meet the above conditions. For example, the conductivity of the CeBr ₃ material used in the utility model is not as good as that of aluminum and steel , but the price is more expensive than aluminum and steel. If this material is directly used to make the flip connection piece, then in order to ensure the flow capacity, it needs to be made very thick, which will cause problems such as large volume, high cost, and difficult deformation. In contrast, the utility model only uses the shape memory material to make the temperature deformable part 44 that does not need to conduct electricity, which can greatly expand the choice of materials, and is conducive to reducing the production cost and manufacturing difficulty of the secondary battery.

The conductive boss 46 includes a sheet-shaped positioning portion 460 and a protruding portion 462 protruding upward from the positioning portion 460 . The positioning part 460 is fixed on the conductive top cover sheet 20 below the flip connecting piece 402 and is electrically connected to the conductive top cover sheet 20. The raised portion 462 is aligned with the floating end of the flipped connecting piece 402, and the height of the raised portion 462 needs to be ensured. It can be in close contact with the flipped connecting piece 402 to be electrically connected, so that the first pole 22 and the second pole 24 are electrically connected to realize an external short circuit of the secondary battery, effectively ensuring the safety of the battery cell. The fixing method of the positioning part 460 on the conductive top cover sheet 20 can be welding, riveting, mechanical fitting, glue bonding or other suitable methods, but it is necessary to ensure that the connection between the two is an electrical connection, preferably welding.

In different implementations, one or more of the following methods can be used to ensure that the flipped connecting piece 402 has a larger contact area with the conductive boss 46 and/or the electrical connection is sufficiently tight: 1) as shown in the figure As shown in 1 to 3, the flip connecting piece 402 is made of elastically deformable material, and when it is in a natural state, the floating end contacts the conductive boss; The end is upturned and separated and insulated from the conductive boss 46, that is to say, the overturning tendency of the floating end of the flip connecting piece 402 approaching the conductive boss 46 is provided by the restoring force of its elastic deformation, only due to the abutment of the temperature deformation member 44 The force is greater than the restoring force of the flip connecting piece 402, so that the flip connecting piece 402 cannot rebound at normal temperature; 2) The flip connecting piece 402 is made of ordinary conductive material, and the spring in a stretched state is used to provide it with a flipping tendency: the lower end of the spring It can be fixed on the insulator 42, the conductive top cover sheet 20 or the conductive boss 46, and the upper end pulls the floating end of the flip connecting piece 402 so that it has a tendency to turn over towards the conductive boss 46; at normal temperature, the flip connecting piece 402 cannot be turned over under the action of the resisting force of the temperature deformable part 44. Once the high temperature makes the temperature deformable part 44 lose its propping function, the turning connecting piece 402 will turn over under the action of the spring tension and be electrically connected to the conductive boss 46; this solution Among them, the spring needs to be an insulating spring or at least one end is provided with an insulating structure to ensure that the secondary battery will not be short-circuited at room temperature due to the existence of the spring; The contact surface of the raised part 462 is set to a shape corresponding to each other, so that the two can fully contact. For example, as shown in FIGS. The top of the protrusion 462 of 46 is provided with a groove 464 that is compatible with the small protrusion 404. When the flip connecting piece 402 is turned down, the small protrusion 404 will be inserted into the groove 464, thereby effectively ensuring sufficient contact between the two ; 4) ensure that the floating end of the flip connecting piece 402 and the raised portion 462 of the conductive boss 46 are tightly connected by appropriate measures, for example, a magnet is set at one of the floating end of the turning connecting piece 402 and the raised portion 462, and the other One is provided with a magnetic adsorption body (including the case where its own material is a magnetic adsorption body), so as to provide a flipping tendency for the flip connecting piece 402 through magnetic attraction force, and make the flipped dangling end closely contact with the raised portion 462 .

As can be seen from the above description, the utility model has at least the following advantages:

1) Based on the deformation characteristics of the temperature deformable part 44 at different temperatures, the temperature deformable part 44 is used as the starting element of the outer short connection device 30, so that the secondary battery can be quickly and reliably realized when the battery cell overcharge temperature rises. The external short circuit effectively avoids the occurrence of overcharging and out of control of the battery cell, ensuring the safety of the battery cell;

2) Make the conductive flip 40 and the conductive boss 46 face each other up and down, and electrically connect the two to the poles with opposite polarities respectively, so that the external short circuit of the secondary battery is only between the conductive flip 40 and the conductive boss 46 There is a breakpoint between them to ensure that the conductive reversing piece 40 can be in contact with the conductive boss 46 after being turned over, so as to realize the external short circuit of the secondary battery; Compared with the utility model, the reliability of the outer short connecting device 30 is greatly improved;

3) The conductive boss 46 is a fixed element. When the flipping connecting piece 402 is at normal temperature, the temperature deformable part 44 is against the top and cannot be turned over or pressed down. Therefore, unless the temperature rises and the temperature deformable part 44 is activated, the secondary battery is not easy to be damaged by mistake. External short circuit occurs due to unexpected events such as contact and strong vibration; compared with the naturally suspended conductive sheet in the existing external short connection device, the possibility of accidental short circuit in the utility model is greatly reduced.

According to the disclosure and teaching of the above specification, those skilled in the art to which the utility model belongs can also make appropriate changes and modifications to the above embodiments. Therefore, the utility model is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the utility model should also fall within the scope of protection of the claims of the utility model. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present utility model.

Claims (10)

1. A secondary battery top cover, characterized in that: Including a conductive top cover sheet, a conductive flip sheet, a conductive boss, a temperature deformation piece, a first pole and a second pole; The first pole and the second pole respectively pass through the conductive top cover, and the first pole is electrically insulated from the conductive top cover, and the second pole is electrically connected to the conductive top cover; The conductive overturning piece is electrically connected to the first pole and electrically insulated from the conductive top cover; the conductive boss is installed under the conductive overturning piece and is electrically connected to the second pole through the conductive top cover; There is a gap between the bosses to insulate each other, but there is a tendency to turn over towards the conductive boss; The temperature deformable part is arranged under the conductive reversing sheet, which resists the conductive reversing sheet and competes with the reversing tendency of the conductive reversing sheet, so that the conductive reversing sheet cannot be turned at room temperature; When the temperature rise causes the temperature of the temperature-deformed part to reach or exceed its deformation temperature, the temperature-deformed part will undergo memory deformation and no longer touch the conductive flipping piece, and the conductive flipping piece will turn over under the action of the flipping trend and be electrically connected to the conductive boss , so that the first pole and the second pole are electrically connected. 2. The top cover of the secondary battery according to claim 1, characterized in that: the conductive turning piece includes a pole connecting piece and a turning connecting piece; the pole connecting piece covers the outer peripheral wall of the first pole and is connected to the second One pole is electrically connected; the overturned connecting piece is a conductive piece that can be actively deformed or deformed by force, one end of which is electrically connected to the pole connecting piece, and the other end is a floating end that has a tendency to turn over towards the conductive boss. 3. The top cover of the secondary battery according to claim 2, characterized in that: it also includes an insulator fixed on the conductive top cover sheet, the insulator is installed between the conductive flip sheet and the conductive top cover sheet, above which Then, the conductive flipping piece is supported to prevent the flipping connecting piece from contacting the conductive top cover sheet; the temperature deformable part is installed between the flipping connecting piece and the insulating piece, one end is fixed on the insulating piece, and the free end is tilted up and resisted Flip over the connector. 4. The top cover of the secondary battery according to claim 3, characterized in that: the flip connecting piece is made of elastically deformable material, and when it is in a natural state, the floating end contacts the conductive boss; The resisting force causes elastic deformation of the overturned connecting piece, and the floating end is upturned to be separated and insulated from the conductive boss. 5. The top cover of the secondary battery according to claim 3, characterized in that: the turning tendency of the turning connecting piece close to the conductive boss is provided by a stretched spring; the lower end of the spring is fixed on the insulator, the conductive top On the cover sheet or the conductive boss, the upper end pulls the floating end of the flip connecting piece so that it has a tendency to turn over towards the conductive boss; the spring is an insulating spring or at least one end is provided with an insulating structure to ensure that the secondary battery will not be damaged due to The existence of the spring and the external short circuit at room temperature. 6. The top cover of the secondary battery according to claim 2, characterized in that: the conductive boss includes a sheet-shaped positioning part and a raised part protruding upward from the positioning part; The conductive top cover sheet is electrically connected to the conductive top cover sheet, and the raised part is aligned with the floating end of the turning connection sheet. 7. The top cover of the secondary battery according to claim 6, characterized in that: the contact surface of the floating end of the flip connection piece and the raised portion of the conductive boss is set in a shape corresponding to each other. 8. The top cover of the secondary battery according to claim 7, characterized in that: the floating end of the flip connecting piece is provided with a small protrusion facing the raised part, and the top of the raised part of the conductive boss is provided with a small The protrusion is matched with the groove; when the turning connecting piece is turned over to the conductive boss, the small protrusion is inserted into the groove. 9. The top cover of the secondary battery according to claim 6, characterized in that: at least one of the floating end of the flip connecting piece and the raised portion of the conductive boss is provided with a magnet, and the other is provided with a magnetic absorber, through which the magnet The suction force provides a turning tendency for the turning connecting piece, and makes the turned free end and the raised part closely contact. 10. A secondary battery, comprising a casing, an electric core, and a secondary battery top cover; the electric core is accommodated in the casing, and the top cover is installed on the casing; it is characterized in that: the secondary battery top cover is The secondary battery top cover according to any one of claims 1 to 9.