CN112072010A - Battery cover plate assembly and single battery - 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 plate assembly and single battery

Technical Field

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

Background

In order to meet the continuously-improved endurance mileage of the electric automobile, the energy density of the power battery is higher and higher, and in recent years, safety accidents caused by overcharge frequently occur. In order to reduce the occurrence of safety accidents and improve the safety of power batteries, the problem of improving the safety of overcharge, overheating and the like on the structure of the power batteries needs to be solved urgently.

At present, a mechanical overturning piece is arranged on a common power battery cover plate, and when the air pressure in the battery is increased, the overturning piece overturns, so that a circuit is cut off to improve the overcharge safety of the battery. In recent years, improved flip sheet designs have also been proposed to ameliorate the problem of large contact resistance of conventional flip sheets. However, both the conventional flip sheet and the improved flip sheet require the air pressure inside the battery to reach the flipping pressure of the mechanical flip sheet for flipping. A certain amount of lithium carbonate needs to be added to the positive electrode of the battery, which decomposes to produce carbon dioxide when the battery reaches its decomposition voltage. The addition of the lithium carbonate not only reduces the energy density of the whole battery core, but also has great negative effects on the cycle and storage performance of the battery, and meanwhile, the mechanical turnover sheet has the phenomena of fatigue and aging, and the reliability of the mechanical turnover sheet is always a pain point which is difficult to avoid in the industry.

Disclosure of Invention

In view of the above, it is desirable to provide a battery cover plate assembly and a single battery to solve the above problems.

The invention relates to a battery cover plate component, which comprises a conductive plate, a positive terminal, a negative 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 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.

In one embodiment, the MIT element is made of a phase transition material; alternatively, the outer surface of the MIT member is uniformly plated with a phase transition material.

In one embodiment, 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.

In one embodiment, 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.

In one embodiment, the first temperature ranges from 40 ℃ to 70 ℃; the second temperature is in the range of 70 ℃ to 150 ℃.

In one embodiment, the first temperature is 68 ℃ and the second temperature is 80 ℃ to 120 ℃.

In one embodiment, 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.

In one embodiment, a surface of the MIT member adjacent to the PTC member is provided with a concavo-convex structure, and/or a surface of the PTC member adjacent to the MIT member is provided with a concavo-convex structure.

In one embodiment, the battery cover plate assembly further comprises 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.

The invention also provides a single battery, which comprises a battery core, an insulating film, a shell and any one of the battery cover plate assemblies, wherein the battery core is provided with a positive electrode lug and a negative electrode lug, the positive electrode lug is used for being electrically connected with the positive electrode terminal, and the negative electrode lug 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.

The invention has the beneficial effects that:

according to the battery cover plate assembly and the single battery, the MIT-PTC composite safety assembly is connected between the negative electrode terminal and the conducting plate in series, and gas generation additives such as lithium carbonate do not need to be added into a battery pole piece, so that the cycle and storage performance of the battery are not influenced; meanwhile, the risk that the battery core is ignited and explodes due to the fact that the battery temperature is continuously increased because the discharge current of the MIT element used singly is not controllable is avoided. In addition, the MIT-PTC composite safety assembly is adopted to replace an insulating sheet between the original cathode terminal and the optical aluminum sheet, no additional device is added, no additional space is occupied, the phenomena of fatigue and aging of a mechanical overturning sheet are avoided, and the reliability is fully ensured.

Drawings

Fig. 1 is a schematic structural diagram of a battery according to an embodiment of the present invention.

Fig. 2 is an exploded schematic view of a battery cover plate assembly according to an embodiment of the present invention.

Fig. 3 is a partial longitudinal sectional view schematically illustrating an MIT-PTC composite safety assembly according to an embodiment of the present invention.

Fig. 4 is a partial longitudinal sectional view schematically illustrating an MIT-PTC composite safety assembly according to another embodiment of the present invention.

Fig. 5 is a partial longitudinal sectional view schematically illustrating an MIT-PTC composite safety assembly according to still another embodiment of the present invention.

Fig. 6 is a partial longitudinal sectional view schematically illustrating an MIT-PTC composite safety assembly according to still another embodiment of the present invention.

Fig. 7 is a partial longitudinal sectional view schematically illustrating an MIT-PTC composite safety assembly according to still another embodiment of the present invention.

Reference numerals:

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

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

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

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements 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 the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

The invention provides a battery cover plate assembly and a single battery, wherein, in one embodiment, the structure of the single battery 10 is as shown in fig. 1, and the battery cover plate assembly comprises a battery core 100, an insulating film 200, a shell 300 and a battery cover plate assembly 400, wherein a positive electrode tab 110 and a negative electrode tab 120 are arranged on the battery core 100, the positive electrode tab 110 is used for being electrically connected with a positive electrode terminal 420 on the battery cover plate assembly 400, and the negative electrode tab 120 is used for being electrically connected with a negative electrode terminal 430 on the battery cover plate assembly 400; the battery cell 100 and the insulating film 200 are both disposed in the casing 300, and the insulating film 200 is coated outside the battery cell 100, so as to prevent the battery cell 100 from being short-circuited due to direct contact with the inner wall of the casing 300. In addition, as shown in fig. 1, the upper portion of the housing 300 is opened, and the battery cover assembly 400 is covered at the opening of the housing 300.

In one embodiment, the explosion structure of the battery cover plate assembly 400 is shown in fig. 2 and includes a conductive plate 410, a positive terminal 420, a negative terminal 430, an MIT-PTC composite safety assembly 440, an insulating plate 450, a positive post 460, a negative post 470, and an insulating sealing plug 480. The positive terminal 420 is electrically connected above the conductive plate 410, a resistor sheet 490 is also connected in series between the positive terminal 420 and the conductive plate 410, and the MIT-PTC compound safety assembly 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 under the conductive plate 410 to prevent the battery cell 100 from contacting the conductive plate 410 to be short-circuited. The conductive plate 410 is provided with a first via hole 411 and a second via hole 412 which are spaced from each other, the insulating plate 450 is provided with a third via hole 451 and a fourth via hole 452 which are spaced from each other, the resistor sheet 490 is provided with a fifth via hole 491, the MIT-PTC composite safety assembly 440 is provided with a sixth via hole 443, the first via hole 411, the third via hole 451, and the fifth via hole 491 are positioned correspondingly to each other, the second via hole 412, the fourth via hole 452, and the sixth via hole 443 are positioned correspondingly to each other, and the positive post 460 is inserted into the third via hole 451, the first via hole 411, and the fifth via hole 491 for electrically connecting the positive tab 110 of the battery cell 100 and the positive terminal 420; the negative pole pillar 470 is disposed through the fourth via hole 452, the second via hole 412 and the sixth via hole 443, and is used to electrically connect the negative pole tab 120 of the battery cell 100 and the negative pole terminal 430; the insulating sealing plug 480 is hermetically arranged between the hole wall of the conductive plate 410 and the positive pole 460 and the negative pole 470, so as to avoid short circuit caused by direct contact of the positive pole 460 and the negative pole 470 with the conductive plate 410. In addition, the insulating sealing plug 480 also serves to seal the gaps between the first via hole 411 and the positive post 460, and between the second via hole 412 and the negative post 470.

In a specific embodiment, as shown in fig. 2, the battery cover plate assembly 400 further includes a positive adapter sheet 510 and a negative adapter sheet 520, the positive adapter sheet 510 is used for electrically connecting the positive tab 110 of the battery cell 100 and the positive post 460, and the negative adapter sheet 520 is used for electrically connecting the negative tab 110 of the battery cell 100 and the negative post 460. Specifically, the positive electrode tab 110 of the battery cell 100 is welded and fixed on one surface of the positive electrode adaptor sheet 510 (not shown in the figure), one end of the positive electrode pillar 460 is welded and fixed on the other surface of the positive electrode adaptor sheet 510, and the other end of the positive electrode pillar 460 sequentially passes through the third via hole 451, the first via hole 411 and the fifth via hole 491 to be electrically connected with the positive electrode terminal 420. The negative tab 120 of the battery cell 100 is welded and fixed to one surface of the negative adaptor sheet 520 (not shown in the drawings), one end of the negative post 470 is welded and fixed to the other surface of the negative adaptor sheet 520, and the other end of the negative post 470 sequentially passes through the fourth via hole 452, the second via hole 412 and the sixth via hole 443 to be electrically connected to the negative terminal 430.

In the present invention, the number of the first through hole 411 to the fourth through hole 452, the number of the positive post 460 and the number of the negative post 470 are not limited, and in the embodiment shown in fig. 2, the number of the first through hole 411 to the fourth through hole 452 is two, and the number of the positive post 460 and the number of the negative post 470 are also two. It is understood that, in other embodiments, the number of the first through holes 411 to the fourth through holes 452 may be one or two or more, and the number of the positive posts 460 and the negative posts 470 may be one or two or more, as long as the number of the positive posts 460 is equal to the number of the first through holes 411, the third through holes 451, and the fifth through holes 491, and the number of the negative posts 470 is equal to the number of the second through holes 412, the fourth through holes 452, and the sixth through holes 443. Note that the resistor sheet 490 connected in series between the positive electrode terminal 420 and the conductive plate 410 is used to reduce a short-circuit current when the battery 10 is short-circuited, and in other embodiments, the resistor sheet 490 may be omitted.

A partial longitudinal sectional structure of the MIT-PTC composite safety assembly 440 is shown in fig. 3, and includes an MIT component 441 and a PTC component 442 connected in series with each other, the MIT component 441 being an insulator at a normal temperature, which is a temperature environment having a temperature of less than 40 ℃, the MIT component 441 at the normal temperature being capable of preventing conduction between the negative terminal 430 and the conductive plate 410, 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 ℃, the MIT element 441 is abruptly changed from an insulator to a conductor to conduct the negative terminal 430 and the conductive plate 410, so that the battery 10 forms an external short circuit, thereby being capable of timely releasing electric energy in the battery 10, effectively preventing an external circuit from continuously charging the battery 10 during overcharge, and improving the safety of the battery 10. When the temperature further increases to a second temperature, which is greater than the first temperature, the resistance of the PTC device 442 increases abruptly, so that the short-circuit current can be limited together with the resistor sheet 490, so that the battery 10 is always in a safe state, and thermal runaway of the battery 10 is prevented.

In one embodiment, the MIT element 441 is made of a phase transition material; alternatively, the outer surface of the MIT member 441 is uniformly plated with a phase transition material. The phase transition material may be vanadium oxide (VOx) or a rare earth nickel-based perovskite oxide (ReNiO3: Re ═ Sm, Nd, Eu) material. In other embodiments, the vanadium oxide or rare earth nickel-based perovskite oxide material may be doped with at least one of W, St, La, Ba elements. The doped elements may lower or raise the phase transition temperature of the vanadium oxide or rare earth nickel-based perovskite oxide material. For example, when the MIT element 441 is made of a vanadium oxide (VOx) material, the phase transition temperature of the MIT element 441 is 68 ℃, and when the temperature reaches 68 ℃, the MIT element 441 is transformed from an insulator to a conductor. In some application scenarios, when it is required to lower or increase the phase transition temperature of MIT, at least one of W, St, La, Ba elements may be doped in the vanadium oxide (VOx) material.

In one embodiment, the PTC component 442 is made of a PTC semiconductor material; alternatively, the outer surface of the PTC component 442 is uniformly plated with a PTC semiconductor material; the resistance of the PTC semiconductor material increases with increasing temperature. In one embodiment, the first temperature at which the phase transition of the MIT element 441 occurs is in a range of 40 ℃ to 70 ℃; the transition temperature of the PTC component 442 ranges from 70 ℃ to 150 ℃. In a specific embodiment, the MIT element 441 is made of a vanadium oxide (VOx) material having a phase transition temperature of 68 ℃, i.e., a first temperature of 68 ℃; the transition temperature of the PTC component 442 is between 80 ℃ and 120 ℃, i.e., the second temperature is between 80 ℃ and 120 ℃.

In one embodiment, a partial longitudinal sectional cut-away structure of the MIT-PTC composite safety component 440 is shown in fig. 3, an MIT component 441 is made of a phase transition material vanadium oxide (VOx) sheet, and a PTC component 442, which is a PTC thin film, is directly plated on the MIT component 441. In another embodiment, a partial longitudinal sectional view structure of the MIT-PTC composite safety device 440 is shown in fig. 4, the PTC device 442 is made of a PTC semiconductor sheet, and the MIT device 441 is an MIT thin film directly plated on the PTC device 442. In still another embodiment, a partial longitudinal sectional cut-away structure of the MIT-PTC composite safety assembly 440 is shown in fig. 5, an MIT component 441 is made of a phase transition material vanadium oxide (VOx) sheet, a PTC component 442 is made of a PTC semiconductor sheet, and the MIT component 441 is bonded to the PTC component 442 by a conductive paste 444.

In addition, in order to improve the connection firmness between the MIT member 441 and the PTC member 442, as shown in fig. 6, the MIT member 441 is an MIT thin film plated on the PTC member 442, and a concave-convex structure is provided on a side of the MIT thin film adjacent to the PTC member 442 and a concave-convex structure is also provided on a side of the PTC member 442 adjacent to the MIT thin film, so that the connection surface between the MIT member 441 and the PTC member 442 is made uneven, and the surface area of the connection surface between the MIT member 441 and the PTC member 442 is increased, thereby increasing the connection firmness between the MIT member 441 and the PTC member 442. In the embodiment shown in fig. 6, the MIT member 441 is an MIT thin film and is plated on the PTC member 442. It is understood that, in other embodiments, the PTC component 442 may be a thin film, plated on the MIT component 441.

In another embodiment, as shown in fig. 7, the MIT member 441 is adhered to the PTC member 442 by a conductive paste 444, a concavo-convex structure is provided on one surface of the MIT member 441 adjacent to the PTC member 442, and a concavo-convex structure is also provided on one surface of the PTC member 442 adjacent to the MIT member 441, so that the connection surface between the conductive paste 444 and the MIT member 441 and the connection surface between the conductive paste 444 and the PTC member 442 are all concavo-convex, increasing the surface area between the conductive paste 444 and the MIT member 441 and the PTC member 442, thereby increasing the adhesion firmness of the MIT member 441 and the PTC member 442. Note that, in the embodiment shown in fig. 7, the uneven structure is provided on the side of the MIT member 441 adjacent to the PTC member 442, and the uneven structure is also provided on the side of the PTC member 442 adjacent to the MIT member 441, thereby increasing the adhesion firmness of the conductive paste 444 to both the MIT member 441 and the PTC member 442. It is understood that, in other embodiments, the concavo-convex structure may be further provided on a surface of the MIT member 441 adjacent to the PTC member 442 or the concavo-convex structure may be provided on a surface of the PTC member 442 adjacent to the MIT member 441, and thus, the firmness of the adhesion of the MIT member 441 to the PTC member 442 may be increased.

In one particular embodiment, the conductive plate 410 is a sheet of bare aluminum. When the charging temperature of the battery 10 is normal, the MIT element 441 of the MIT-PTC composite safety assembly 440 is an insulator, and the negative terminal 430 and the optical aluminum sheet are not conducted; when overcharge occurs, heat is generated inside the battery 10 and the negative pole 470 itself generates insulation state-metal state phase transition within 1 second by joule heat, when the temperature of the MIT element 441 in the MIT-PTC composite safety assembly 440 reaches a first temperature, for example, 68 ℃, the MIT-PTC composite safety assembly 440 becomes a conductor, and the negative terminal 430 and the optical aluminum sheet are conducted to form an external short circuit, thereby releasing the internal energy of the battery 10 in time; meanwhile, as the short-circuit discharge progresses, the temperature of the negative pole 470 further increases, and when the temperature of the PTC component 442 in the MIT-PTC compound safety assembly 440 reaches a second temperature, for example, 80 ℃, the resistance of the PTC component 442 rapidly increases, so that the short-circuit can be effectively limited, and the thermal runaway of the power battery 10 can be prevented, thereby implementing the overcharge and overheat protection of the lithium ion battery 10 and improving the safety of the power battery 10 during charging.

In another specific embodiment, when the battery 10 is left exposed in a high temperature environment, an external environment transfers heat to the MIT-PTC composite safety device 440 through the negative terminal 430 and the optical aluminum sheet, when the temperature of the MIT element 441 in the MIT-PTC composite safety device 440 reaches a first temperature, for example, 68 ℃, an insulation-metal phase transition occurs within 1 second, the MIT-PTC composite safety device 440 becomes a conductor, conduction is made between the negative terminal 430 and the optical aluminum sheet, an external short circuit is formed, internal energy of the battery 10 is timely discharged, and the charged state of the battery 10 is lowered; meanwhile, as the short-circuit discharge progresses, the temperature of the negative pole 470 further increases, and when the temperature of the PTC component 442 in the MIT-PTC compound safety assembly 440 reaches its transition temperature, for example, 80 ℃, the resistance of the PTC component 442 rapidly increases, so that it is possible to effectively limit the short-circuit and prevent the power battery 10 from thermal runaway, thereby achieving protection of the lithium ion battery 10 from an overheat environment and improving safety of the power battery 10 when overheated.

In still another specific embodiment, when the temperature of the battery 10 is normal, the MIT element 441 of the MIT-PTC composite safety assembly 440 is an insulator, and the negative terminal 430 is not in conduction with the optical aluminum sheet; when the battery 10 is short-circuited externally, the MIT-PTC composite safety assembly 440 becomes a conductor when the temperature of the MIT component 441 in the MIT-PTC composite safety assembly 440 rapidly reaches the first temperature, for example, 68 ℃, due to the joule heat generated inside the battery 10 and the action of the negative pole 470 itself, and as the short-circuit discharge progresses, the temperature of the negative pole 470 further increases, so that the temperature of the PTC component 442 reaches the transition temperature thereof to reach the second temperature, for example, 80 ℃, the resistance of the PTC component 442 rapidly increases, so that the resistance of the MIT-PTC composite safety assembly 440 in the on state rapidly increases, thereby effectively limiting the short-circuit and preventing the thermal runaway of the power battery 10, thereby realizing the short-circuit overheat protection of the lithium ion battery 10 and improving the safety of the power battery 10 during charging.

According to the battery cover plate assembly 400 and the single battery 10, the MIT-PTC composite safety assembly 440 is connected between the negative electrode terminal 430 and the conductive plate 410 in series, and gas generation additives such as lithium carbonate do not need to be added into the pole piece of the battery 10, so that the circulation and storage performance of the battery 10 are not influenced; meanwhile, the risk that the discharge current of the MIT element used singly is not controllable, which may cause the temperature of the battery 10 to continuously rise and cause the electric core 100 to explode due to fire is avoided. In addition, the MIT-PTC composite safety assembly 440 is adopted to replace an insulating sheet between the original cathode terminal 430 and the aluminum flake, so that additional devices are not added, additional space is not occupied, the phenomena of fatigue and aging of a mechanical overturning sheet are avoided, and the reliability is fully ensured.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent 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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