CN112072010A - Battery cover assembly and single cell - Google Patents

Abstract

The invention relates to a battery cover plate component and an electric battery, wherein the battery cover plate component comprises a conductive plate, a positive electrode terminal, a negative electrode terminal and an MIT-PTC composite safety component; the positive terminal can be electrically connected with a positive electrode lug of the battery cell, and the negative terminal can be electrically connected with a negative electrode lug of the battery cell; the positive terminal is electrically connected above the conductive plate, and the MIT-PTC composite safety assembly is connected in series between the upper surface of the conductive plate and the negative terminal; the MIT-PTC composite safety assembly includes an MIT component and a PTC component connected in series with each other, the MIT component for abrupt transition from an insulator to a conductor at a first temperature to conduct a negative terminal with a conductive plate so that the battery forms an external short circuit; the PTC component is used for sudden resistance increase at a second temperature so as to limit short-circuit current; the second temperature is greater than the first temperature. The battery cover plate assembly and the single battery do not influence the cycle and storage performance of the battery, simultaneously avoid the problems of fatigue and aging of a mechanical turnover sheet, and fully ensure the reliability.

Description

Battery cover assembly and single cell

technical field

The present invention relates to the technical field of batteries, in particular to a battery cover plate assembly and a single battery.

Background technique

In order to meet the increasing cruising range of electric vehicles, the energy density of power batteries is getting higher and higher. In recent years, safety accidents caused by overcharging have occurred frequently. In order to reduce the occurrence of safety accidents and improve the safety of power batteries, the problems of improving the safety of overcharge and overheating in the structure of power batteries need to be solved urgently.

At present, the ordinary power battery cover plate is provided with a mechanical flip sheet. When the air pressure inside the battery increases, the flip sheet is flipped over, thereby cutting off the circuit to improve the overcharge safety of the battery. In recent years, an improved flip chip design has also been proposed to improve the problem of large contact resistance of the traditional flip chip. However, whether it is a traditional flip sheet or an improved flip sheet, the internal air pressure of the battery needs to reach the flip pressure of the mechanical flip sheet before it can be flipped. A certain amount of lithium carbonate needs to be added to the positive electrode of the battery, and the lithium carbonate decomposes to produce carbon dioxide when the battery reaches its decomposition voltage. The addition of lithium carbonate not only reduces the energy density of the entire cell, but also has a negative impact on the battery cycle and storage performance. At the same time, the mechanical flip sheet has fatigue and aging phenomena, and its reliability has always been unavoidable in the industry. Pain points.

SUMMARY OF THE INVENTION

Based on this, it is necessary to provide a battery cover plate assembly and a single battery to solve the above problems.

A battery cover plate assembly of the present invention includes a conductive plate, a positive terminal, a negative terminal and a MIT-PTC composite safety component; the positive terminal can be electrically connected to the positive tab of the battery cell, and the negative terminal can be connected to the battery core. The negative electrode tab is electrically connected; the positive terminal is electrically connected above the conductive plate, and the MIT-PTC composite safety component is connected in series between the upper surface of the conductive plate and the negative terminal; the MIT-PTC The composite safety assembly includes an MIT part and a PTC part that are connected in series, the MIT part is used to change from an insulator to a conductor at a first temperature, so as to conduct the negative terminal and the conductive plate, so that the battery forms an external short circuit; the PTC part is used The resistance increases sharply at a second temperature to limit the short-circuit current; the second temperature is greater than the first temperature.

In one embodiment, the MIT part is made of a phase change material; or, the outer surface of the MIT part is uniformly coated with a phase change material.

In one embodiment, the phase transition material is vanadium oxide or rare earth nickel based perovskite oxide material; or, the phase transition material is vanadium oxide or rare earth nickel based perovskite oxide material, the phase transition material is The material is also doped with at least one of W, St, La and Ba elements.

In one embodiment, the PTC component is made of PTC semiconductor material; or, the outer surface of the PTC component is uniformly plated with PTC semiconductor material; the resistance value of the PTC semiconductor material increases as the temperature increases.

In one embodiment, the range of the first temperature is 40°C-70°C; the range of the second temperature is 70°C-150°C.

In one embodiment, the first temperature is 68°C, and the second temperature is 80°C-120°C.

In one embodiment, the MIT component is an MIT film and is plated on the PTC component; or, the PTC component is a PTC thin film and is plated on the MIT component; or, the MIT component is electrically conductive The glue is bonded to the PTC parts.

In one embodiment, a concave-convex structure is provided on a side of the MIT component close to the PTC component, and/or a concave-convex structure is provided on a side of the PTC component close to the MIT component.

In one embodiment, the battery cover plate assembly further includes an insulating plate, a positive pole, a negative pole, and an insulating sealing plug; the insulating plate is arranged below the conductive plate, and the conductive plate is provided with mutually spaced first through holes and The second via hole, the insulating plate is provided with a third via hole and a fourth via hole spaced apart from each other, and the MIT-PTC composite safety component is provided with a sixth via hole. The positions of the three via holes correspond to the positions of the second via hole, the fourth via hole and the sixth via hole, and the positive pole is penetrated through the first via hole and the third via hole. In the hole, it is used to electrically connect the positive electrode tab and the positive terminal of the cell; the negative pole is penetrated in the second, fourth and sixth via holes for electrically connecting the A negative electrode tab and a negative electrode terminal; the insulating sealing plug is sealed and arranged between the hole wall of the conductive plate and the positive pole and the negative pole.

The present invention also provides a single battery, comprising a cell, an insulating film, a casing and any one of the above-mentioned battery cover plate assemblies, the cell is provided with a positive electrode tab and a negative electrode tab, and the positive electrode is provided with a positive electrode tab and a negative electrode tab. The lug is used for electrical connection with the positive terminal, and the negative electrode lug is used for electrical connection with the negative terminal; the insulating film is wrapped on the outside of the battery core, and the battery core and the insulating film are both arranged on the In the casing, the upper part of the casing is opened, and the battery cover plate assembly is covered at the opening of the casing.

According to the present invention, its beneficial effects are:

In the battery cover plate assembly and the single battery of the present invention, by connecting the MIT-PTC composite safety component in series between the negative terminal and the conductive plate, no gas-generating additives such as lithium carbonate are added to the battery pole pieces, so the cycle of the battery is not affected. and storage performance; at the same time, it avoids the uncontrollable discharge current of a single MIT component, which may cause the battery temperature to continue to rise and lead to the risk of cell fire and explosion. In addition, the present invention uses the MIT-PTC composite safety component to replace the original insulating sheet between the negative terminal and the light aluminum sheet, does not add additional devices and does not occupy additional space, and avoids fatigue and aging of the mechanical flip sheet. phenomenon, the reliability is fully guaranteed.

Description of drawings

FIG. 1 is a schematic structural diagram of a battery provided by an embodiment of the present invention.

FIG. 2 is a schematic diagram of an exploded structure of a battery cover plate assembly provided by an embodiment of the present invention.

FIG. 3 is a partial longitudinal cross-sectional schematic diagram of an MIT-PTC composite safety component provided by an embodiment of the present invention.

FIG. 4 is a partial longitudinal cross-sectional schematic diagram of an MIT-PTC composite safety component provided by another embodiment of the present invention.

FIG. 5 is a partial longitudinal cross-sectional schematic diagram of a MIT-PTC composite safety component provided by another embodiment of the present invention.

FIG. 6 is a partial longitudinal cross-sectional schematic diagram of an MIT-PTC composite safety component provided by another embodiment of the present invention.

FIG. 7 is a partial longitudinal cross-sectional schematic diagram of an MIT-PTC composite safety component provided by another embodiment of the present invention.

Reference number:

Battery 10, battery cell 100, positive electrode tab 110, negative electrode tab 120, insulating film 200, casing 300, battery cover plate assembly 400, conductive plate 410, first via hole 411, second via hole 412, positive electrode Terminal 420, negative terminal 430, MIT-PTC composite safety component 440, MIT component 441, PTC component 442, sixth via hole 443, conductive glue 444, insulating plate 450, third via hole 451, fourth via hole 452 , the positive pole 460 , the negative pole 470 , the insulating sealing plug 480 , the resistance sheet 490 , the fifth conducting hole 491 , the positive transition piece 510 , and the negative pole transition piece 520 .

Detailed ways

In order to make the above objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", " Back, Left, Right, Vertical, Horizontal, Top, Bottom, Inner, Outer, Clockwise, Counterclockwise, Axial , "radial", "circumferential" and other indicated orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying the indicated device or Elements must have a particular orientation, be constructed and operate in a particular orientation and are therefore not to be construed as limitations of the invention.

In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature delimited with "first", "second" may expressly or implicitly include at least one of that feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise expressly and specifically defined.

In the present invention, unless otherwise expressly specified and limited, terms such as "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection , or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between the two elements, unless otherwise specified limit. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

In the present invention, unless otherwise expressly specified and limited, a first feature "on" or "under" a second feature may be in direct contact between the first and second features, or the first and second features indirectly through an intermediary touch. Also, the first feature being "above", "over" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is level higher than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly or obliquely below the second feature, or simply means that the first feature has a lower level than the second feature.

It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or an intervening element may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for the purpose of illustration only and do not represent the only embodiment.

The present invention provides a battery cover assembly and a single battery, wherein, in one embodiment, the structure of the single battery 10 is shown in FIG. 1 , including a battery cell 100 , an insulating film 200 , a casing 300 and a battery cover In the assembly 400, the battery cell 100 is provided with a positive electrode tab 110 and a negative electrode tab 120, the positive electrode tab 110 is used for electrical connection with the positive terminal 420 on the battery cover plate assembly 400, and the negative electrode tab 120 is used for the battery cover plate assembly. The negative terminal 430 on the 400 is electrically connected; the battery core 100 and the insulating film 200 are both arranged in the casing 300, and the insulating film 200 is wrapped outside the battery core 100 to prevent the battery core 100 from directly contacting the inner wall of the casing 300. short circuit. In addition, as shown in FIG. 1 , the upper part of the casing 300 is opened, and the battery cover plate assembly 400 is covered at the opening of the casing 300 .

In one embodiment, the explosion structure of the battery cover plate assembly 400 is shown in FIG. 2 , including a conductive plate 410 , a positive terminal 420 , a negative terminal 430 , an MIT-PTC composite safety component 440 , an insulating plate 450 , a positive pole 460 , and a negative pole Post 470 and insulating sealing plug 480. The positive terminal 420 is electrically connected to the top of the conductive plate 410 , a resistor sheet 490 is connected in series between the positive terminal 420 and the conductive plate 410 , and the MIT-PTC composite safety component 440 is connected in series between the upper surface of the conductive plate 410 and the negative terminal 430 . The insulating plate 450 is disposed below the conductive plate 410 to prevent the cell 100 from being short-circuited due to contact with the conductive plate 410 . The conductive plate 410 is provided with a first conductive hole 411 and a second conductive hole 412 spaced apart from each other, the insulating plate 450 is provided with a third conductive hole 451 and a fourth conductive hole 452 spaced apart from each other, and the resistance sheet 490 A fifth via hole 491 is provided, and a sixth via hole 443 is provided on the MIT-PTC composite safety component 440. The positions of the first via hole 411, the third via hole 451, and the fifth via hole 491 correspond to each other , the positions of the second via hole 412 , the fourth via hole 452 and the sixth via hole 443 correspond to each other, and the positive pole 460 penetrates through the third via hole 451 , the first via hole 411 and the fifth via hole 443 In the hole 491, it is used to electrically connect the positive electrode tab 110 and the positive terminal 420 of the battery cell 100; In order to electrically connect the negative electrode tab 120 and the negative electrode terminal 430 of the battery cell 100; the insulating sealing plug 480 is sealed and arranged between the hole wall of the conductive plate 410 and the positive electrode column 460 and the negative electrode column 470, so as to prevent the positive electrode column 460 and the negative electrode column 470 from being directly connected to each other. Contact the conductive plate 410 to cause a short circuit. In addition, the insulating sealing plug 480 is also used to seal the gaps between the first conductive hole 411 and the positive electrode column 460 and between the second conductive hole 412 and the negative electrode column 470 .

In a specific embodiment, as shown in FIG. 2 , the battery cover plate assembly 400 further includes a positive electrode adapter sheet 510 and a negative electrode adapter sheet 520 , and the positive electrode adapter sheet 510 is used to electrically connect the positive electrode tab 110 of the battery cell 100 . With the positive pole 460 , the negative adapter 520 is used to electrically connect the negative tab 110 of the battery cell 100 and the negative pole 460 . Specifically, the positive electrode tab 110 of the battery cell 100 is welded and fixed on one side of the positive electrode adapter plate 510 (not shown in the figure), and one end of the positive electrode column 460 is welded and fixed on the other side of the positive electrode adapter plate 510. The other end of 460 is electrically connected to the positive terminal 420 through the third conducting hole 451 , the first conducting hole 411 and the fifth conducting hole 491 in sequence. The negative electrode tab 120 of the battery cell 100 is welded and fixed on one side of the negative electrode adapter plate 520 (not shown in the figure), one end of the negative electrode column 470 is welded and fixed on the other side of the negative electrode adapter plate 520, and the other side of the negative electrode column 470 is welded and fixed. One end is electrically connected to the negative terminal 430 through the fourth conducting hole 452 , the second conducting hole 412 and the sixth conducting hole 443 in sequence.

In addition, it should be noted that the present invention does not limit the number of the first via hole 411 to the fourth via hole 452, as well as the positive pole 460 and the negative pole 470. In the embodiment shown in FIG. The number of the first through hole 411 to the fourth through hole 452 is two, and the number of the positive pole 460 and the negative pole 470 is also two. It can be understood that, in other embodiments, the number of the first via hole 411 to the fourth via hole 452 may be one or more than two, and the number of the positive pole 460 and the negative pole 470 may also be one or more. More than two, as long as the number of the positive poles 460 is equal to the number of the first conduction holes 411, the third conduction holes 451, and the fifth conduction holes 491, and the number of the negative poles 470 is equal to the number of the second conduction holes 412, the fourth conduction holes The numbers of the via holes 452 and the sixth via holes 443 may be equal. In addition, it should be noted that the resistor sheet 490 connected in series between the positive terminal 420 and the conductive plate 410 is used to reduce the short-circuit current when the battery 10 is short-circuited. In other embodiments, the resistor sheet 490 can be omitted.

The partial longitudinal cross-sectional structure of the MIT-PTC composite safety component 440 is shown in FIG. 3, including the MIT component 441 and the PTC component 442 connected in series with each other. In a temperature environment of 40° C., the MIT component 441 at room temperature can prevent the negative terminal 430 and the conductive plate 410 from being conductive, thereby preventing the battery 10 from forming an external short circuit. When the temperature rises to the first temperature, which is greater than or equal to 40°C, the MIT component 441 changes from an insulator to a conductor, so as to conduct the negative terminal 430 and the conductive plate 410, so that the battery 10 forms an external short circuit, Therefore, the electric energy in the battery 10 can be released in time, and the external circuit can also be effectively prevented from continuing to charge the battery 10 during overcharging, thereby improving the safety of the battery 10 . When the temperature is further increased to the second temperature, the second temperature mentioned here is greater than the first temperature, the resistance of the PTC component 442 increases sharply, so that the short-circuit current can be limited together with the resistance sheet 490, so that the battery 10 is always in a safe state, Thermal runaway of the battery 10 is avoided.

In one embodiment, the MIT part 441 is made of a phase change material; alternatively, the outer surface of the MIT part 441 is uniformly coated with the phase change material. The phase transition material may be vanadium oxide (VOx) or rare earth nickel-based perovskite oxide (ReNiO3:Re=Sm,Nd,Eu) material. In other embodiments, vanadium oxide or rare earth nickel-based perovskite oxide material may also be doped with at least one of W, St, La, and Ba elements. Doping elements can lower or increase the phase transition temperature of vanadium oxide or rare earth nickel-based perovskite oxide materials. For example, when the MIT part 441 is made of vanadium oxide (VOx) material, the phase transition temperature of the MIT part 441 is 68°C, and when the temperature reaches 68°C, the MIT part 441 is transformed from an insulator to a conductor. In some application scenarios, when the phase transition temperature of the MIT needs to be lowered or raised, the vanadium oxide (VOx) material may be doped with at least one of W, St, La, and Ba elements.

In one embodiment, the PTC component 442 is made of PTC semiconductor material; alternatively, the outer surface of the PTC component 442 is uniformly plated with the PTC semiconductor material; the resistance of the PTC semiconductor material increases with increasing temperature. In one embodiment, the first temperature at which the MIT part 441 undergoes phase transition is in the range of 40°C to 70°C; the transition temperature of the PTC part 442 is in the range of 70°C to 150°C. In a specific embodiment, the MIT part 441 is made of a vanadium oxide (VOx) material, and the phase transition temperature of the vanadium oxide (VOx) material is 68° C., that is, the first temperature is 68° C. The transition temperature of the PTC part 442 is Between 80°C-120°C, that is, the second temperature is 80°C-120°C.

In one embodiment, the partial longitudinal cross-sectional sectional structure of the MIT-PTC composite safety component 440 is shown in FIG. 3 , the MIT component 441 is made of a phase-change material vanadium oxide (VOx) sheet, and the PTC component 442 is a PTC film, directly Plated on the MIT part 441. In another embodiment, the partial longitudinal cross-sectional structure of the MIT-PTC composite security component 440 is shown in FIG. 4 , the PTC component 442 is made of a PTC semiconductor wafer, and the MIT component 441 is an MIT film, which is directly plated on the PTC component 442 on. In yet another embodiment, a partial longitudinal cross-sectional cross-sectional structure of the MIT-PTC composite security component 440 is shown in FIG. 5 , the MIT component 441 is made of a phase change material vanadium oxide (VOx) sheet, and the PTC component 442 is made of a PTC semiconductor sheet The MIT part 441 is bonded together with the PTC part 442 by the conductive glue 444 .

In addition, in order to improve the connection firmness between the MIT part 441 and the PTC part 442 , as shown in FIG. 6 , the MIT part 441 is an MIT film, which is plated on the PTC part 442 . Concave-convex structure, the side of the PTC part 442 close to the MIT film is also provided with a concave-convex structure, so that the connection surface between the MIT part 441 and the PTC part 442 is uneven, and the connection surface between the MIT part 441 and the PTC part 442 is increased. surface area, thereby increasing the connection firmness between the MIT part 441 and the PTC part 442 . It should be noted that, in the embodiment shown in FIG. 6 , the MIT component 441 is an MIT thin film, which is plated on the PTC component 442 . It can be understood that, in other embodiments, the PTC component 442 may be a thin film, which is plated on the MIT component 441 .

In another embodiment, as shown in FIG. 7 , the MIT part 441 is bonded to the PTC part 442 through the conductive glue 444 , a concave-convex structure is provided on the side of the MIT part 441 close to the PTC part 442 , and the PTC part 442 is close to the MIT part 441 . A concave-convex structure is also provided on one side, so that the connection surface between the conductive adhesive 444 and the MIT part 441 and the connection surface between the conductive adhesive 444 and the PTC part 442 are uneven, and the conductive adhesive 444 and the MIT part 441 are increased. The surface area between the PTC parts 442 increases the bonding firmness of the MIT parts 441 and the PTC parts 442 . It should be noted that, in the embodiment shown in FIG. 7 , the concave-convex structure is provided on the side of the MIT part 441 close to the PTC part 442 , and the concave-convex structure is also provided on the side of the PTC part 442 close to the MIT part 441 , thereby increasing the size of the The adhesiveness of the conductive adhesive 444 to both the MIT part 441 and the PTC part 442 . It can be understood that, in other embodiments, a concave-convex structure may also be provided on the side of the MIT component 441 close to the PTC component 442, or a concave-convex structure may be provided on the side of the PTC component 442 close to the MIT component 441. The adhesiveness of the MIT member 441 and the PTC member 442 can be increased.

In a specific embodiment, the conductive plate 410 is a plain aluminum sheet. When the charging temperature of the battery 10 is normal, the MIT component 441 in the MIT-PTC composite safety assembly 440 is an insulator, and there is no conduction between the negative terminal 430 and the bare aluminum sheet; and when overcharging occurs, the battery 10 generates heat inside and the negative electrode Under the action of the Joule heat of the column 470 itself, when the temperature of the MIT component 441 in the MIT-PTC composite security component 440 reaches a first temperature, for example, 68° C., an insulating state-metal state phase transition occurs within 1 second, and the MIT-PTC composite security component 440 becomes a conductor, making the connection between the negative terminal 430 and the light aluminum sheet, forming an external short circuit, and releasing the internal energy of the battery 10 in time; at the same time, as the short-circuit discharge progresses, the temperature of the negative pole 470 further increases. When the MIT-PTC composite safety component 440 When the temperature of the PTC component 442 reaches the second temperature, for example, at 80° C., the resistance of the PTC component 442 increases rapidly, which can effectively limit the short circuit and prevent the thermal runaway of the power battery 10 , thereby realizing the protection of the lithium ion battery 10 . Overcharging and overheating protection improves the safety of the power battery 10 when charging.

In another specific embodiment, when the battery 10 is left standing and exposed to a high temperature environment, the external environment transfers heat to the MIT-PTC composite safety component 440 through the negative terminal 430 and the light aluminum sheet. When the MIT-PTC composite safety component 440 contains the MIT When the temperature of the component 441 reaches the first temperature, for example, 68° C., the insulating state-metal state phase transition occurs within 1 second, and the MIT-PTC composite safety component 440 becomes a conductor, so that the negative terminal 430 and the light aluminum sheet are connected to form an external state. Short circuit, the internal energy of the battery 10 is released in time, and the state of charge of the battery 10 is reduced; at the same time, as the short-circuit discharge progresses, the temperature of the negative pole 470 is further increased. When the temperature of the PTC component 442 in the MIT-PTC composite safety assembly 440 reaches its transition temperature, for example , At 80°C, the resistance of the PTC component 442 increases rapidly, which can effectively limit the short circuit and prevent the power battery 10 from thermal runaway, thereby realizing the overheating environment protection of the lithium ion battery 10 and improving the power battery 10 when it is overheated. safety.

In yet another specific embodiment, when the temperature of the battery 10 is normal, the MIT component 441 in the MIT-PTC composite safety assembly 440 is an insulator, and there is no conduction between the negative terminal 430 and the light aluminum sheet; and when the battery 10 is short-circuited , under the action of the heat generated inside the battery 10 and the Joule heat of the negative pole 470 itself, the temperature of the MIT component 441 in the MIT-PTC composite safety component 440 rapidly reaches the first temperature, for example, when the temperature is 68°C, the MIT-PTC composite safety component 440 becomes a conductor, As the short-circuit discharge progresses, the temperature of the negative pole 470 is further increased, so that the temperature of the PTC component 442 reaches its transition temperature and reaches the second temperature, for example, when 80° C., the resistance of the PTC component 442 increases rapidly, so that the MIT in the conducting state - The resistance of the PTC composite safety component 440 increases rapidly, which can effectively limit the short circuit circuit and prevent the power battery 10 from thermal runaway, thereby realizing the short-circuit overheating protection of the lithium ion battery 10 and improving the safety of the power battery 10 during charging.

In the battery cover plate assembly 400 and the single battery 10 of the present invention, the MIT-PTC composite safety assembly 440 is connected in series between the negative terminal 430 and the conductive plate 410, and no gas-generating additives such as lithium carbonate are added to the pole pieces of the battery 10. Therefore, the cycle and storage performance of the battery 10 is not affected; at the same time, the uncontrollable discharge current of a single MIT element is avoided, which may cause the temperature of the battery 10 to continue to rise and cause the battery 100 to catch fire and explode. In addition, the present invention uses the MIT-PTC composite safety component 440 to replace the original insulating sheet between the negative terminal 430 and the bare aluminum sheet, without adding additional devices and occupying additional space, while avoiding fatigue and fatigue of the mechanical flip sheet. Aging phenomenon, reliability is fully guaranteed.

The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity, all possible combinations of the technical features in the above-described embodiments are not described. However, as long as there is no contradiction between the combinations of these technical features, All should be regarded as the scope described in this specification.

The above-mentioned embodiments only represent several embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as a limitation on the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can also be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims (10)

1. A battery cover plate assembly includes a conductive plate, a positive terminal, a negative terminal, and an MIT-PTC composite safety assembly; the positive terminal can be electrically connected with a positive electrode lug of the battery cell, and the negative terminal can be electrically connected with a negative electrode lug of the battery cell; the positive terminal is electrically connected above the conductive plate, and the MIT-PTC composite safety assembly is connected in series between an upper surface of the conductive plate and a negative terminal;

the MIT-PTC composite safety assembly includes an MIT component and a PTC component connected in series with each other, the MIT component for abrupt transition from an insulator to a conductor at a first temperature to conduct a negative terminal and a conductive plate such that a battery forms an external short circuit; the PTC component is used for suddenly increasing the resistance at a second temperature so as to limit short-circuit current; the second temperature is greater than the first temperature.

2. The battery cover plate assembly of claim 1, wherein the MIT member is made of a phase transition material; alternatively, the outer surface of the MIT member is uniformly plated with a phase transition material.

3. The battery cover plate assembly of claim 2, wherein the phase change material is a vanadium oxide or rare earth nickel-based perovskite oxide material; or the phase transition material is vanadium oxide or a rare earth nickel-based perovskite oxide material, and at least one of W, St, La and Ba elements is doped in the phase transition material.

4. The battery cover plate assembly of claim 1, wherein the PTC component is made of a PTC semiconductor material; or the outer surface of the PTC component is uniformly plated with a PTC semiconductor material; the resistance value of the PTC semiconductor material increases with an increase in temperature.

5. The battery cover plate assembly of claim 1, wherein the first temperature is in a range of 40 ℃ to 70 ℃; the second temperature is in the range of 70 ℃ to 150 ℃.

6. The battery cover plate assembly of claim 5, wherein the first temperature is 68 ℃ and the second temperature is 80 ℃ to 120 ℃.

7. The battery cover plate assembly of claim 1, wherein the MIT member is an MIT thin film plated on the PTC member; or, the PTC component is a PTC thin film and is plated on the MIT component; alternatively, the MIT member is adhered to the PTC member by a conductive paste.

8. The battery cover plate assembly of claim 1, wherein the MIT member is provided with a concavo-convex structure on a side thereof adjacent to the PTC member, and/or the PTC member is provided with a concavo-convex structure on a side thereof adjacent to the MIT member.

9. The battery cover plate assembly of claim 1, further comprising an insulating plate, a positive post, a negative post, and an insulating sealing plug; the insulating plate is arranged below the current-conducting plate, a first via hole and a second via hole which are mutually spaced are formed in the current-conducting plate, a third via hole and a fourth via hole which are mutually spaced are formed in the insulating plate, a sixth via hole is formed in the MIT-PTC composite safety component, the first via hole and the third via hole are corresponding in position, the second via hole, the fourth via hole and the sixth via hole are corresponding in position, and the positive post penetrates through the first via hole and the third via hole and is used for electrically connecting a positive pole lug and a positive terminal of the battery cell; the negative pole column penetrates through the second via hole, the fourth via hole and the sixth via hole and is used for electrically connecting a negative pole lug of the battery cell with the negative pole terminal; the insulating sealing plug is arranged between the hole wall of the current-conducting plate and the positive pole column and the negative pole column in a sealing mode.

10. A single battery, comprising a battery core, an insulating film, a shell and the battery cover assembly of any one of claims 1 to 9, wherein the battery core is provided with a positive electrode tab and a negative electrode tab, the positive electrode tab is used for being electrically connected with the positive electrode terminal, and the negative electrode tab is used for being electrically connected with the negative electrode terminal; the insulation film is coated outside the battery core, the battery core and the insulation film are arranged in the shell, an opening is formed in the upper portion of the shell, and the battery cover plate assembly is covered on the opening of the shell.

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