Battery cover assembly and single battery

Abstract

The present invention relates to a battery cover plate assembly and a single cell battery. The battery cover plate assembly 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 electrode tab of the battery cell, and the negative terminal can be electrically connected to the negative electrode tab of the battery cell. 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 composite safety component includes a MIT component and a PTC component connected in series. The MIT component is used to suddenly change from an insulator to a conductor at a first temperature to conduct the negative terminal and the conductive plate, causing the battery to form an external short circuit. The PTC component is used to suddenly increase the resistance at a second temperature to limit the short circuit current. The second temperature is greater than the first temperature. The battery cover plate assembly and the single cell battery of the present invention do not affect the cycle and storage performance of the battery, and at the same time avoid the fatigue and aging problems of the mechanical flip chip, ensuring sufficient reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a battery cover assembly and a single battery. Background Art

[0002] To meet the continuously 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. To reduce the occurrence of safety accidents and improve the safety of power batteries, it is urgent to solve the problem of improving the safety of overcharging, overheating, etc. in the structure of power batteries.

[0003] Currently, ordinary power battery covers are provided with mechanical flip pieces. When the internal pressure of the battery increases, the flip pieces flip, thereby cutting off the circuit to improve the overcharging safety of the battery. In recent years, some people have also proposed improved flip piece designs, which have improved the problem of large contact resistance of traditional flip pieces. However, whether it is a traditional flip piece or an improved flip piece, the internal pressure of the battery needs to reach the flipping pressure of the mechanical flip piece to flip. It is necessary to add a certain amount of lithium carbonate to the positive electrode of the battery. 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 battery cell, but also has a greater negative impact on the battery cycle and storage performance. At the same time, the mechanical flip piece has the phenomena of fatigue and aging, and its reliability has always been a pain point that is difficult to avoid in the industry. Summary of the Invention

[0004] Based on this, it is necessary to provide a battery cover assembly and a single battery to solve the above problems.

[0005] A battery cover assembly of the present invention includes a conductive plate, a positive terminal, a negative terminal, and an MIT-PTC composite safety component; the positive terminal can be electrically connected to the positive electrode tab of the battery cell, and the negative terminal can be electrically connected to the negative electrode tab of the battery cell; 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 composite safety component includes an MIT component and a PTC component connected in series with each other. The MIT component is used to suddenly change from an insulator to a conductor at a first temperature to conduct the negative terminal and the conductive plate, so that the battery forms an external short circuit; the PTC component is used to suddenly increase the resistance at a second temperature to limit the short-circuit current; the second temperature is greater than the first temperature.

[0006] In one embodiment, the MIT component is made of a phase change material; or, the outer surface of the MIT component is uniformly coated with a phase change material.

[0007] In one embodiment, the phase change material is vanadium oxide or rare earth nickel-based perovskite oxide material; alternatively, the phase change material is vanadium oxide or rare earth nickel-based perovskite oxide material, and at least one of the elements W, St, La, and Ba is further doped in the phase change material.

[0008] In one embodiment, the PTC component is made of PTC semiconductor material; alternatively, the outer surface of the PTC component is uniformly coated with PTC semiconductor material; the resistance value of the PTC semiconductor material increases with the increase of temperature.

[0009] 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.

[0010] In one embodiment, the first temperature is 68°C, and the second temperature is 80°C - 120°C.

[0011] In one embodiment, the MIT component is an MIT thin film, which is plated on the PTC component; alternatively, the PTC component is a PTC thin film, which is plated on the MIT component; alternatively, the MIT component is bonded to the PTC component through a conductive adhesive.

[0012] In one embodiment, the surface of the MIT component close to the PTC component is provided with a concavo-convex structure, and / or the surface of the PTC component close to the MIT component is provided with a concavo-convex structure.

[0013] In one embodiment, the battery cover assembly further includes an insulating plate, a positive electrode post, a negative electrode post, and an insulating seal plug; the insulating plate is arranged below the conductive plate, the conductive plate is provided with a first conductive through hole and a second conductive through hole spaced from each other, the insulating plate is provided with a third conductive through hole and a fourth conductive through hole spaced from each other, the MIT-PTC composite safety component is provided with a sixth conductive through hole, the positions of the first conductive through hole and the third conductive through hole correspond to each other, the positions of the second conductive through hole, the fourth conductive through hole, and the sixth conductive through hole correspond to each other, the positive electrode post is inserted into the first conductive through hole and the third conductive through hole for electrically connecting the positive electrode tab of the battery cell and the positive terminal; the negative electrode post is inserted into the second conductive through hole, the fourth conductive through hole, and the sixth conductive through hole for electrically connecting the negative electrode tab of the battery cell and the negative terminal; the insulating seal plug is hermetically arranged between the hole wall of the conductive plate and the positive electrode post and the negative electrode post.

[0014] The present invention also provides a single cell, which includes a battery cell, an insulating film, a housing, and the battery cover plate assembly described in any one of the above. The battery cell is provided with a positive electrode tab and a negative electrode tab. The positive electrode tab is used for electrically connecting to the positive terminal, and the negative electrode tab is used for electrically connecting to the negative terminal. The insulating film is coated outside the battery cell, and both the battery cell and the insulating film are arranged inside the housing. The housing has an opening at the upper part, and the battery cover plate assembly covers the opening of the housing.

[0015] The beneficial effects of the present invention are as follows:

[0016] For the battery cover plate assembly and the single cell of the present invention, by serially connecting a MIT-PTC composite safety component between the negative terminal and the conductive plate, gas-producing additives such as lithium carbonate do not need to be added to the battery electrode sheet, thus not affecting the cycle and storage performance of the battery. At the same time, it avoids the risk that the discharge current of a single MIT component is uncontrollable, which may cause the battery temperature to continuously rise and lead to the risk of the battery cell catching fire and exploding. In addition, the present invention uses a MIT-PTC composite safety component to replace the insulating sheet between the original negative terminal and the light aluminum sheet, without adding additional devices and without occupying additional space. At the same time, it avoids the phenomena of fatigue and aging of the mechanical flip sheet, and the reliability is fully guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of a battery provided by an embodiment of the present invention.

[0018] Figure 2 It is an exploded structural diagram of a battery cover plate assembly provided by an embodiment of the present invention.

[0019] Figure 3 It is a partial longitudinal sectional view schematic diagram of a MIT-PTC composite safety component provided by an embodiment of the present invention.

[0020] Figure 4 It is a partial longitudinal sectional view schematic diagram of a MIT-PTC composite safety component provided by another embodiment of the present invention.

[0021] Figure 5 It is a partial longitudinal sectional view schematic diagram of a MIT-PTC composite safety component provided by yet another embodiment of the present invention.

[0022] Figure 6 It is a partial longitudinal sectional view schematic diagram of a MIT-PTC composite safety component provided by yet another embodiment of the present invention.

[0023] Figure 7 It is a partial longitudinal sectional view schematic diagram of a MIT-PTC composite safety component provided by yet another embodiment of the present invention.

[0024] Reference Numerals:

[0025] Battery 10, battery cell 100, positive electrode tab 110, negative electrode tab 120, insulating film 200, housing 300, battery cover assembly 400, conductive plate 410, first via hole 411, second via hole 412, positive terminal 420, negative terminal 430, MIT-PTC composite safety component 440, MIT component 441, PTC component 442, sixth via hole 443, conductive adhesive 444, insulating plate 450, third via hole 451, fourth via hole 452, positive electrode post 460, negative electrode post 470, insulating seal plug 480, resistor sheet 490, fifth via hole 491, positive electrode adapter piece 510, negative electrode adapter piece 520. Detailed Embodiments

[0026] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the following describes the detailed embodiments of the present invention in conjunction with the accompanying drawings. Many specific details are set forth in the following description in order to fully understand 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.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0028] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0029] In the present invention, unless otherwise clearly specified or defined, terms such as "installed", "connected", "joined", "fixed", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly defined. 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 circumstances.

[0030] In the present invention, unless otherwise clearly specified or defined, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature can be that the first feature is directly above or obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature can be that the first feature is directly below or obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0031] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation.

[0032] The present invention provides a battery cover assembly and a single cell battery. Among them, in one embodiment, the structure of the single cell battery 10 is as Figure 1 shown, including a battery core 100, an insulating film 200, a housing 300 and a battery cover assembly 400. A positive electrode tab 110 and a negative electrode tab 120 are provided on the battery core 100. The positive electrode tab 110 is used for electrically connecting with the positive terminal 420 on the battery cover assembly 400, and the negative electrode tab 120 is used for electrically connecting with the negative terminal 430 on the battery cover assembly 400. Both the battery core 100 and the insulating film 200 are disposed in the housing 300, and the insulating film 200 is wrapped around the outside of the battery core 100 to prevent the battery core 100 from directly contacting the inner wall of the housing 300 and causing a short circuit. In addition, as Figure 1 shown, the housing 300 is open at the top, and the battery cover assembly 400 is covered on the opening of the housing 300.

[0033] In one embodiment, the explosion structure of the battery cover assembly 400 is as Figure 2As shown in the figure, it includes a conductive plate 410, a positive terminal 420, a negative terminal 430, a MIT-PTC composite safety component 440, an insulating plate 450, a positive electrode post 460, a negative electrode post 470, and an insulating sealing plug 480. The positive terminal 420 is electrically connected above the conductive plate 410, and a resistor chip 490 is also connected in series between the positive terminal 420 and the conductive plate 410. 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 arranged below the conductive plate 410 to prevent the battery cell 100 from contacting the conductive plate 410 and causing a short circuit. The conductive plate 410 is provided with a first through hole 411 and a second through hole 412 spaced apart from each other. The insulating plate 450 is provided with a third through hole 451 and a fourth through hole 452 spaced apart from each other. The resistor chip 490 is provided with a fifth through hole 491. The MIT-PTC composite safety component 440 is provided with a sixth through hole 443. The positions of the first through hole 411, the third through hole 451, and the fifth through hole 491 correspond to each other. The positions of the second through hole 412, the fourth through hole 452, and the sixth through hole 443 correspond to each other. The positive electrode post 460 passes through the third through hole 451, the first through hole 411, and the fifth through hole 491 for electrically connecting the positive electrode tab 110 of the battery cell 100 to the positive terminal 420. The negative electrode post 470 passes through the fourth through hole 452, the second through hole 412, and the sixth through hole 443 for electrically connecting the negative electrode tab 120 of the battery cell 100 to the negative terminal 430. The insulating sealing plug 480 is hermetically arranged between the hole wall of the conductive plate 410 and the positive electrode post 460 and the negative electrode post 470 to prevent the positive electrode post 460 and the negative electrode post 470 from directly contacting the conductive plate 410 and causing a short circuit. In addition, the insulating sealing plug 480 is also used to seal the gaps between the first through hole 411 and the positive electrode post 460 and between the second through hole 412 and the negative electrode post 470.

[0034] In a specific embodiment, such as Figure 2As shown, the battery cover plate assembly 400 further includes a positive transfer piece 510 and a negative transfer piece 520. The positive transfer piece 510 is used to electrically connect the positive electrode tab 110 of the battery cell 100 to the positive electrode column 460, and the negative transfer piece 520 is used to electrically connect the negative electrode tab 110 of the battery cell 100 to the negative electrode column 460. Specifically, the positive electrode tab 110 of the battery cell 100 is welded and fixed on one side of the positive transfer piece 510 (not shown in the figure), one end of the positive electrode column 460 is welded and fixed on the other side of the positive transfer piece 510, and the other end of the positive electrode column 460 sequentially passes through the third through hole 451, the first through hole 411, and the fifth through hole 491 to be electrically connected to the positive terminal 420. The negative electrode tab 120 of the battery cell 100 is welded and fixed on one side of the negative transfer piece 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 transfer piece 520, and the other end of the negative electrode column 470 sequentially passes through the fourth through hole 452, the second through hole 412, and the sixth through hole 443 to be electrically connected to the negative terminal 430.

[0035] In addition, it should be noted that the present invention does not limit the number of the first through hole 411 to the fourth through hole 452, as well as the number of the positive electrode column 460 and the negative electrode column 470. In Figure 2 the illustrated embodiment, the number of the first through hole 411 to the fourth through hole 452 is two, and the number of the positive electrode column 460 and the negative electrode column 470 is also two. It can be understood that in other embodiments, the number of the first through hole 411 to the fourth through hole 452 can also be one or more than two, and the number of the positive electrode column 460 and the negative electrode column 470 can also be one or more than two, as long as the number of the positive electrode column 460 is equal to the number of the first through hole 411, the third through hole 451, and the fifth through hole 491, and the number of the negative electrode column 470 is equal to the number of the second through hole 412, the fourth through hole 452, and the sixth through hole 443. In addition, it should be noted that the resistance piece 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 externally. In other embodiments, the resistance piece 490 can be omitted.

[0036] The partial longitudinal sectional structure of the MIT-PTC composite safety component 440 is as Figure 3As shown in the figure, it includes an MIT component 441 and a PTC component 442 connected in series. The MIT component 441 is an insulator at normal temperature, where the normal temperature refers to a temperature environment with a temperature less than 40 °C. The MIT component 441 at normal temperature can prevent the negative terminal 430 and the conductive plate 410 from conducting, thereby avoiding an external short circuit of the battery 10. When the temperature rises to the first temperature, where the first temperature is greater than or equal to 40 °C, the MIT component 441 suddenly changes from an insulator to a conductor to conduct the negative terminal 430 and the conductive plate 410, causing the battery 10 to form an external short circuit, so that the electrical energy in the battery 10 can be released in time, and it can also effectively prevent the external circuit from continuing to charge the battery 10 during overcharging, improving the safety of the battery 10. When the temperature further rises to the second temperature, where the second temperature is greater than the first temperature, the resistance of the PTC component 442 suddenly increases, so that it can limit the short-circuit current together with the resistor sheet 490, keeping the battery 10 in a safe state all the time and avoiding thermal runaway of the battery 10.

[0037] In one embodiment, the MIT component 441 is made of a phase change material; alternatively, the outer surface of the MIT component 441 is uniformly coated with a phase change material. The phase change material can be vanadium oxide (VOx) or rare earth nickel-based perovskite oxide (ReNiO3: Re = Sm, Nd, Eu) material. In some other embodiments, at least one of the elements W, St, La, and Ba can also be doped in the vanadium oxide or rare earth nickel-based perovskite oxide material. The doped elements can lower or raise the phase transition temperature of the vanadium oxide or rare earth nickel-based perovskite oxide material. For example, when the MIT component 441 is made of vanadium oxide (VOx) material, the phase transition temperature of the MIT component 441 is 68 °C. When the temperature reaches 68 °C, the MIT component 441 changes from an insulator to a conductor. In certain application scenarios, when it is necessary to lower or raise the phase transition temperature of the MIT, at least one of the elements W, St, La, and Ba can be doped in the vanadium oxide (VOx) material.

[0038] 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 coated with a PTC semiconductor material; the resistance value of the PTC semiconductor material increases with the increase of temperature. In one embodiment, the range of the first temperature at which the MIT component 441 undergoes a phase transition is 40 °C - 70 °C; the transition temperature range of the PTC component 442 is 70 °C - 150 °C. In a specific embodiment, the MIT component 441 is made of 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 component 442 is between 80 °C and 120 °C, that is, the second temperature is 80 °C - 120 °C.

[0039] In one embodiment, the partial longitudinal cross-sectional structure of the MIT-PTC composite safety component 440 is as shown in Figure 3 . The MIT component 441 is made of a phase change material vanadium oxide (VOx) sheet, and the PTC component 442 is a PTC thin film directly plated on the MIT component 441. In another embodiment, the partial longitudinal cross-sectional structure of the MIT-PTC composite safety component 440 is as shown in Figure 4 . The PTC component 442 is made of a PTC semiconductor sheet, and the MIT component 441 is an MIT thin film directly plated on the PTC component 442. In yet another embodiment, the partial longitudinal cross-sectional structure of the MIT-PTC composite safety component 440 is as shown in Figure 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 component 441 is bonded to the PTC component 442 through a conductive adhesive 444.

[0040] In addition, in order to improve the connection firmness between the MIT component 441 and the PTC component 442, as shown in Figure 6 , the MIT component 441 is an MIT thin film plated on the PTC component 442. An uneven structure is provided on the surface of the MIT thin film close to the PTC component 442, and an uneven structure is also provided on the surface of the PTC component 442 close to the MIT thin film. Thus, the connection surface between the MIT component 441 and the PTC component 442 is uneven, increasing the surface area of the connection surface between the MIT component 441 and the PTC component 442, and thus increasing the connection firmness between the MIT component 441 and the PTC component 442. It should be noted that in the embodiment shown in Figure 6 , the MIT component 441 is an MIT thin film plated on the PTC component 442. It can be understood that in other embodiments, the PTC component 442 can be a thin film plated on the MIT component 441.

[0041] In another embodiment, as shown in Figure 7 , the MIT component 441 is bonded to the PTC component 442 through a conductive adhesive 444. An uneven structure is provided on the surface of the MIT component 441 close to the PTC component 442, and an uneven structure is also provided on the surface of the PTC component 442 close to the MIT component 441. Thus, the connection surfaces between the conductive adhesive 444 and the MIT component 441 and between the conductive adhesive 444 and the PTC component 442 are both uneven, increasing the surface areas between the conductive adhesive 444 and the MIT component 441 and the PTC component 442, and thus increasing the bonding firmness between the MIT component 441 and the PTC component 442. It should be noted that in Figure 7In the illustrated embodiment, the surface of the MIT component 441 close to the PTC component 442 is provided with uneven structures, and the surface of the PTC component 442 close to the MIT component 441 is also provided with uneven structures, thereby increasing the bonding firmness between the conductive adhesive 444 and both the MIT component 441 and the PTC component 442. It can be understood that in other embodiments, uneven structures can also be provided on the surface of the MIT component 441 close to the PTC component 442, or on the surface of the PTC component 442 close to the MIT component 441. Designed in this way, the bonding firmness between the MIT component 441 and the PTC component 442 can also be increased.

[0042] In a specific embodiment, the conductive plate 410 is a light aluminum sheet. When the charging temperature of the battery 10 is normal, the MIT component 441 in the MIT-PTC composite safety component 440 is an insulator, and there is no conduction between the negative terminal 430 and the light aluminum sheet; while when overcharging occurs, under the action of the heat generated inside the battery 10 and the Joule heat of the negative electrode post 470 itself, when the temperature of the MIT component 441 in the MIT-PTC composite safety component 440 reaches the first temperature, for example, 68 °C, an insulation-metal phase transition occurs within 1 second, and the MIT-PTC composite safety component 440 becomes a conductor, enabling conduction between the negative terminal 430 and the light aluminum sheet, forming an external short circuit, and timely releasing the internal energy of the battery 10; at the same time, as the short-circuit discharge progresses, the temperature of the negative electrode post 470 further increases. When the temperature of the PTC component 442 in the MIT-PTC composite safety component 440 reaches the second temperature, for example, 80 °C, the resistance of the PTC component 442 rapidly increases, thereby effectively restricting the short-circuit current and preventing the power battery 10 from experiencing thermal runaway, thereby achieving overcharge and overheat protection for the lithium-ion battery 10 and improving the safety of the power battery 10 during charging.

[0043] In another specific embodiment, when the battery 10 is stationary 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 temperature of the MIT component 441 in the MIT-PTC composite safety component 440 reaches the first temperature, for example, 68 °C, an insulation-metal phase transition occurs within 1 second, and the MIT-PTC composite safety component 440 becomes a conductor, enabling conduction between the negative terminal 430 and the light aluminum sheet, forming an external short circuit, and timely releasing the internal energy of the battery 10 and reducing the charging state of the battery 10; at the same time, as the short-circuit discharge progresses, the temperature of the negative electrode post 470 further increases. When the temperature of the PTC component 442 in the MIT-PTC composite safety component 440 reaches its transition temperature, for example, 80 °C, the resistance of the PTC component 442 rapidly increases, thereby effectively restricting the short-circuit current and preventing the power battery 10 from experiencing thermal runaway, thereby achieving overheat protection for the lithium-ion battery 10 and improving the safety of the power battery 10 when overheated.

[0044] In yet another specific embodiment, when the temperature of the battery 10 is normal, the MIT component 441 in the MIT-PTC composite safety component 440 is an insulator, and there is no conduction between the negative terminal 430 and the light aluminum sheet; while when the battery 10 undergoes an external short circuit, due to the internal heat generation of the battery 10 and the Joule heat of the negative electrode post 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 it reaches 68 °C, the MIT-PTC composite safety component 440 becomes a conductor. As the short-circuit discharge proceeds, the temperature of the negative electrode post 470 further increases, causing the temperature of the PTC component 442 to reach its transition temperature, the second temperature, for example, when it reaches 80 °C, the resistance of the PTC component 442 rapidly increases, causing the resistance of the MIT-PTC composite safety component 440 in the conducting state to rapidly increase, thereby effectively limiting the short-circuit current and preventing the power battery 10 from thermal runaway, thus realizing short-circuit overheat protection for the lithium-ion battery 10 and improving the safety of the power battery 10 during charging.

[0045] For the battery cover assembly 400 and the single battery 10 of the present invention, by serially connecting the MIT-PTC composite safety component 440 between the negative terminal 430 and the conductive plate 410, no gas-generating additives such as lithium carbonate need to be added to the battery electrodes, thus not affecting the cycle and storage performance of the battery 10; at the same time, it avoids the risk that the discharge current of a single MIT component is uncontrollable, which may cause the temperature of the battery 10 to continuously rise and lead to the risk of the battery core 100 catching fire and exploding. In addition, the present invention uses the MIT-PTC composite safety component 440 to replace the insulating sheet between the original negative terminal 430 and the light aluminum sheet, without adding additional devices and without occupying additional space, while avoiding the phenomena of fatigue and aging of the mechanical flip sheet, and the reliability is fully guaranteed.

[0046] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope described in this specification.

[0047] The above-described embodiments merely represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A battery cover plate assembly, characterized in that, it 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 electrode tab of the battery cell, and the negative terminal can be electrically connected to the negative electrode tab of the battery cell; 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 composite safety component includes a MIT component and a PTC component connected in series. The MIT component is used to suddenly change from an insulator to a conductor at a first temperature to conduct the negative terminal and the conductive plate, so that the battery forms an external short circuit; the PTC component is used to suddenly increase the resistance at a second temperature to limit the short-circuit current; the second temperature is higher than the first temperature; the MIT component is made of a phase change material; the phase change material is vanadium oxide or rare earth nickel-based perovskite oxide material, and at least one of the elements W, St, La, and Ba is also doped in the phase change material.

2. The battery cover plate assembly according to claim 1, characterized in that, the PTC component is made of a PTC semiconductor material; or, the outer surface of the PTC component is uniformly coated with a PTC semiconductor material; the resistance value of the PTC semiconductor material increases with the increase of temperature.

3. The battery cover plate assembly according to claim 1, characterized in that, the range of the first temperature is 40°C - 70°C; the range of the second temperature is 70°C - 150°C.

4. The battery cover plate assembly according to claim 3, characterized in that, the first temperature is 68°C, and the second temperature is 80°C - 120°C.

5. The battery cover plate assembly according to claim 1, characterized in that, the MIT component is a MIT thin film, plated on the PTC component; or, the PTC component is a PTC thin film, plated on the MIT component; or, the MIT component is bonded to the PTC component through a conductive adhesive.

6. The battery cover plate assembly according to claim 1, characterized in that, a concavo-convex structure is provided on the surface of the MIT component close to the PTC component, and / or a concavo-convex structure is provided on the surface of the PTC component close to the MIT component.

7. The battery cover plate assembly according to claim 1, characterized in that, It further includes an insulating plate, a positive terminal, a negative terminal, and an insulating seal plug; the insulating plate is disposed below the conductive plate, and the conductive plate is provided with a first through hole and a second through hole spaced apart from each other. The insulating plate is provided with a third through hole and a fourth through hole spaced apart from each other. The MIT-PTC composite safety component is provided with a sixth through hole. The positions of the first through hole and the third through hole correspond to each other, and the positions of the second through hole, the fourth through hole, and the sixth through hole correspond to each other. The positive terminal is inserted into the first through hole and the third through hole for electrically connecting the positive electrode tab of the battery cell to the positive terminal; the negative terminal is inserted into the second through hole, the fourth through hole, and the sixth through hole for electrically connecting the negative electrode tab of the battery cell to the negative terminal; the insulating seal plug is hermetically disposed between the hole wall of the conductive plate and the positive terminal and the negative terminal.

8. A single battery cell, characterized in that it includes a battery cell, an insulating film, a housing, and the battery cover assembly according to any one of claims 1-7. The battery cell is provided with a positive electrode tab and a negative electrode tab. The positive electrode tab is used for electrically connecting to the positive terminal, and the negative electrode tab is used for electrically connecting to the negative terminal; the insulating film is coated on the outside of the battery cell, the battery cell and the insulating film are both disposed in the housing, the housing has an opening at the upper part, and the battery cover assembly is covered on the opening of the housing.

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