Upper cover of power battery pack

Abstract

The utility model relates to the technical field of thermal runaway protection assemblies of power battery packs, in particular to an upper cover of a power battery pack. The upper cover of the power battery pack comprises a mica composite cover body and a mica cover plate, the mica composite cover body is provided with a plurality of counter bores penetrating through the upper and lower surfaces; and the mica cover plate is fixedly connected in the counter bore of the mica composite cover body. According to the power battery pack upper cover, the thermal runaway protection performance of the power battery pack can be guaranteed, meanwhile, the overall mass and the assembly cost of the power battery pack can be reduced, and the lightweight design requirement of the power battery pack can be met conveniently.

Description

Technical Field

[0001] The present application relates to the technical field of thermal runaway protection components for power battery packs, and particularly to an upper cover of a power battery pack. Background Art

[0002] The thermal runaway protection safety performance coefficient of the battery module of a new energy vehicle is directly related to the structural design of the battery module. A power lithium battery pack disclosed in Chinese Patent CN206834265U includes: a positive electrode battery box, a negative electrode battery box, a plurality of parallel cylindrical battery cells, a battery cell heat conduction isolation device, a positive electrode welding conductive sheet, a negative electrode welding conductive sheet, a pressure relief isolation plate, a high-temperature resistant insulating sheet, and an isolation plate. The cylindrical battery cells and the battery cell heat conduction isolation device are arranged between the positive electrode battery box and the negative electrode battery box, and the cylindrical battery cells are fixed in the battery cell heat conduction isolation device; the pressure relief isolation plate and the positive electrode welding conductive sheet are arranged on the positive electrode battery box, and the negative electrode welding conductive sheet, the high-temperature resistant insulating sheet, and the isolation plate are arranged on the negative electrode battery box. Among them, the pressure relief isolation plate is assembled closely to the positive electrode parallel busbar, the high-temperature resistant insulating sheet is assembled closely to the negative electrode parallel busbar, and the isolation plate is assembled closely to the high-temperature resistant insulating sheet.

[0003] In the existing power lithium battery pack structure, the high-temperature resistant insulating sheet and the isolation plate with pressure relief holes play a role in safety isolation. However, in the isolation system formed by the high-temperature resistant insulating sheet and the isolation plate, on the one hand, due to the relatively large volume and mass of the two stacked together, it is not conducive to the lightweight design of the power lithium battery pack. On the other hand, compared with a single-piece heat insulation plate, the high-temperature resistant insulating sheet and the isolation plate require relatively more assembly time for assembly production, and the assembly cost is higher, which is not conducive to reducing the overall production cost of the power lithium battery pack. Summary of the Utility Model

[0004] In order to solve the problems existing in the prior art, the present application provides an upper cover of a power battery pack.

[0005] An upper cover of a power battery pack provided by the present application is achieved through the following technical solutions:

[0006] An upper cover of a power battery pack includes a mica composite cover body and a mica cover plate; a plurality of counterbores are provided through the upper and lower surfaces of the mica composite cover body; the mica cover plate is fixedly connected in the counterbores of the mica composite cover body.

[0007] Apply the upper cover of the power battery pack in this application to the power battery pack. When the power battery pack encounters an abnormal thermal runaway situation, individual power batteries in the power battery pack break to generate hot air currents. The hot air currents break through the mica cover plate of the upper cover of the power battery pack, release the hot air currents, and delay the time of short-circuiting or even explosion between the power batteries. Therefore, the upper cover of the power battery pack in this application can ensure the thermal runaway protection performance of the power battery pack, and at the same time can reduce the overall mass and assembly cost of the power battery pack, facilitating the meeting of the lightweight design requirements of the power battery pack.

[0008] Preferably, the mica composite cover body includes a high-strength earthquake-resistant mica straight plate and a high-strength earthquake-resistant mica folded edge, and the high-strength earthquake-resistant mica folded edge is integrally formed on the circumferential side surface in the length direction of the high-strength earthquake-resistant mica straight plate.

[0009] By adopting the above technical solution, it is convenient to install and fix the upper cover of the power battery pack.

[0010] Preferably, the thickness of the mica composite cover body is 0.8 - 2.5 mm; the counterbore is composed of a limit installation hole and a pressure relief hole; the area of the vertical projection of the limit installation hole is 1.05 - 1.20 times the area of the vertical projection of the pressure relief hole; the depth of the limit installation hole is equal to 0.06 - 0.30 times the thickness of the mica composite cover body.

[0011] When the power battery pack encounters an abnormal thermal runaway situation, individual power batteries in the power battery pack break to generate hot air currents. The hot air currents break through the mica cover plate of the upper cover of the power battery pack through the pressure relief hole, release the hot air currents, and delay the time of short-circuiting or even explosion between the power batteries. In this application, the mica composite cover body is used to replace the conventional aluminum alloy upper cover, endowing the battery upper cover with good protection performance, flame retardancy and fire prevention performance, and insulation and electric breakdown resistance performance, and can effectively improve the overall thermal runaway protection performance of the battery pack.

[0012] Preferably, the thickness of the mica composite cover body is 1.98 - 2.02 mm; the depth of the limit installation hole is 0.15 - 0.16 mm; the area of the vertical projection of the limit installation hole is 1.08 - 1.12 times the area of the vertical projection of the pressure relief hole.

[0013] By adopting the above technical solution, through the optimized design of the depth, hole area of the limit installation hole and the depth, hole area of the pressure relief hole, the hot pressing area or the cementing area of the mica composite cover body and the mica cover plate can be adjusted, and further the air pressure for breaking through the mica cover plate of the upper cover of the power battery pack can be adjusted, ensuring that when the power battery pack has a thermal runaway and generates air currents, it can effectively break through the mica cover plate and release the hot air currents outward, delaying the time of short-circuiting or even explosion between the power batteries, and further improving the thermal runaway protection safety performance of the power battery pack.

[0014] Preferably, the method for fixedly connecting the mica cover plate and the counterbore of the mica composite cover body is hot press composite connection.

[0015] By adopting the above technical solution, it is convenient for industrial production of the upper cover of the power battery pack, reducing the overall production cost; in addition, by using the hot press method to produce the upper cover of the power battery pack, the flatness of the surface of the upper cover of the power battery pack can be improved.

[0016] Preferably, the method for fixedly connecting the mica cover plate and the counterbore of the mica composite cover body is glue bonding.

[0017] Preferably, the mica cover plate is fixedly connected to the counterbore of the mica composite cover body by hot melt adhesive.

[0018] When the power battery undergoes thermal runaway and generates hot air flow, the hot melt adhesive in the glued mica cover plate and mica composite cover body has better fluidity after being heated, which can make the hot air flow more easily break through the mica cover plate and release the hot air flow to the outside, delaying the time of series burning or even explosion between power batteries, and further improving the thermal runaway protection safety performance of the power battery pack.

[0019] Preferably, the thickness of the mica cover plate is equal to the depth of the limit mounting hole, that is, the upper surface of the mica cover plate is flush with the upper surface of the mica composite cover body.

[0020] By adopting the above technical solution, the flatness of the surface of the upper cover of the power battery pack can be improved, and the quality of the hot melt adhesive bonding can be grasped through the flatness of the surface of the upper cover of the battery pack, which is convenient for improving the quality stability performance of the surface of the upper cover of the battery pack.

[0021] Preferably, the mica composite cover body is made by hot pressing and bending ten to twenty-six pieces of P506 type mica paper; the mica cover plate is made by hot pressing and cutting one to four pieces of P506 type paper mica; the thickness of the P506 type mica paper is 0.075 - 0.080 mm.

[0022] By adopting the above technical solution, the upper cover of the power battery pack can be mass-produced industrially, which is beneficial to reducing the overall production cost.

[0023] Preferably, the mica composite cover body is integrally cast and hot pressed from special-shaped mica slurry suitable for three-dimensional solid modeling prepared by Zhejiang Rongtai Electric Appliance Co., Ltd.; the mica cover plate is also integrally cast and hot pressed from special-shaped mica slurry suitable for three-dimensional solid modeling prepared by Zhejiang Rongtai Electric Appliance Co., Ltd.

[0024] By adopting the above technical solution, the prepared upper cover of the power battery pack has good mechanical properties, protection properties, flame retardant and fire prevention properties, insulation and anti-electric breakdown properties, which can effectively improve the thermal runaway protection performance of the overall battery pack. The disadvantage is that the cost is relatively high.

[0025] In summary, the present application has the following advantages:

[0026] 1. When the upper cover of the power battery pack in the present application is applied to the power battery pack, in the event of a thermal runaway of the power battery pack, individual power batteries in the power battery pack are broken to generate hot air flow, and the hot air flow breaks through the mica cover plate of the upper cover of the power battery pack to release the hot air flow, delaying the time of series burning or even explosion between the power batteries and improving the thermal runaway protection performance of the power battery pack.

[0027] 2. The upper cover of the power battery pack in the present application can ensure the thermal runaway protection performance of the power battery pack while reducing the overall mass and assembly cost of the power battery pack, facilitating the meeting of the lightweight design requirements of the power battery pack.

[0028] 3. In the present application, a mica composite cover is used to replace the conventional aluminum alloy upper cover, endowing the battery upper cover with good protection performance, flame retardant and fire prevention performance, and insulation and anti-electric breakdown performance, and effectively improving the overall thermal runaway protection performance of the battery pack.

[0029] 4. Through the optimized design of the depth and hole area of the limit installation hole and the depth and hole area of the pressure relief hole, the hot pressing area or bonding area of the mica composite cover and the mica cover plate can be adjusted, and further the air pressure for breaking through the mica cover plate of the upper cover of the power battery pack can be adjusted, ensuring that when the power battery pack has a thermal runaway and generates air flow, it can effectively break through the mica cover plate and release the hot air flow to the outside, delaying the time of series burning or even explosion between the power batteries, and further improving the thermal runaway protection safety performance of the power battery pack.

[0030] 5. When the power battery has a thermal runaway and generates hot air flow, the hot melt adhesive in the adhesively bonded mica cover plate and mica composite cover becomes better fluid after being heated, making it easier for the hot air flow to break through the mica cover plate and release the hot air flow to the outside, delaying the time of series burning or even explosion between the power batteries, and further improving the thermal runaway protection safety performance of the power battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall structure of the upper cover of the power battery pack in an embodiment of the present application.

[0032] Figure 2 It is a cross-sectional view showing the upper cover of the power battery pack in an embodiment of the present application.

[0033] In the figure, 1. mica composite cover; 10. counterbore; 101. limit installation hole; 102. pressure relief hole; 11. high-strength seismic mica straight plate; 12. high-strength seismic mica folded edge; 2. mica cover plate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The present application will be further described in detail below with reference to the drawings and embodiments. Embodiment

[0035] Reference Figure 1 , a top cover of a power battery pack includes a mica composite cover body 1 and a mica cover plate 2 fixedly connected to the mica composite cover body 1. Among them, the mica composite cover body 1 includes a high-strength earthquake-resistant mica straight plate 11 and a high-strength earthquake-resistant mica folded edge 12, and the high-strength earthquake-resistant mica folded edge 12 is integrally formed on the circumferential side surface of the high-strength earthquake-resistant mica straight plate 11 in the length direction.

[0036] Reference Figure 1 , there are two existing preparation methods for the mica composite cover body 1. The first is the most common mica paper hot pressing and cutting method. Specifically, the mica composite cover body 1 is made by hot pressing and bending ten to twenty-six pieces of P506 type mica paper (the thickness of the P506 type mica paper is 0.075 - 0.080 mm) to form a mica substrate, and then the mica substrate is machined to form a number of counterbores 10 to obtain the mica composite cover body 1. The second is the special-shaped mica slurry one-piece casting and hot pressing molding mica composite cover body 1 prepared by Zhejiang Rongtai Electric Appliance Co., Ltd. for three-dimensional stereoscopic modeling, that is, the mica composite cover body 1 is integrally formed with a number of counterbores 10.

[0037] Reference Figure 1 , there are two existing preparation methods for the mica cover plate 2. The first is the most common mica paper hot pressing and cutting method. Specifically, the mica cover plate 2 is made by hot pressing and cutting one to four pieces of P506 type paper mica (the thickness of the P506 type mica paper is 0.075 - 0.080 mm). The second is the special-shaped mica slurry one-piece casting and hot pressing molding mica cover plate 2 prepared by Zhejiang Rongtai Electric Appliance Co., Ltd.

[0038] The special-shaped mica slurry applicable to three-dimensional solid modeling refers to the patent with the application number: CN202111467697X, and the patent name is a special-shaped mica insulating product applicable to three-dimensional solid modeling and its preparation method. Specifically, the special-shaped mica slurry applicable to three-dimensional solid modeling is a mixture of silicone resin and mica slurry in CN202111467697X. Among them, the mica slurry is composed of the following materials: 650 g of muscovite, 80 g of biotite, 150 g of fluorophlogopite, 20 g of A-1120 silane coupling agent, 19.8 g of γ-aluminum oxide fiber, and 0.2 g of silicon carbide whiskers; the silicone resin therein is prepared from 18 g of FM-7721 modified hydroxyl silicone, 49.6 g of methanol, 32 g of KR-242A silicone resin, and 0.2 g of diethylenetriamine. Preparation method of silicone resin: Add 0.05 g of diethylenetriamine, 18 g of FM-7721 modified hydroxyl silicone, and 32 g of methylphenyl silicone resin into a reaction kettle, pre-react at 65 °C for 120 s, cool down to 4 °C, add 49.6 g of methanol, stir at 80 rpm for 10 min, add 0.15 g of diethylenetriamine, and stir at 60 rpm for 2 min to obtain the finished silicone resin.

[0039] The method for integrally casting and hot-pressing a mica composite cover body with the special-shaped mica slurry applicable to three-dimensional solid modeling is as follows:

[0040] S1. Perform ball milling treatment on muscovite, biotite, and fluorophlogopite respectively. Add muscovite, biotite, and fluorophlogopite into a planetary ball mill respectively, ball mill at 50 rpm for 30 min, and then screen with 250-mesh and 600-mesh sieves respectively to obtain muscovite, biotite, and fluorophlogopite with a particle size between 20 and 60 microns. Weigh 650 g of muscovite, 80 g of biotite, and 150 g of fluorophlogopite, place them in a high-speed dispersion kettle, and mix at 120 rpm for 5 min to obtain mica powder.

[0041] S2. Prepare a 4 L surface treatment agent solution by mixing A-1120 silane coupling agent and deionized water at a ratio of 1:200. Place the mica powder in S1 into the 4 L surface treatment agent solution, and under a stirring speed of 120 rpm, perform ultrasonic treatment for 12 min. The ultrasonic frequency is 32 KHz, and the power is 200 W. After the ultrasonic treatment is completed, filter to obtain the powder, and dry the obtained powder at a low temperature of 100 °C to obtain modified mica powder.

[0042] S3. Add 19.4 g of γ-aluminum oxide fiber, 0.6 g of silicon carbide whiskers and 900 g of methanol to the modified mica powder obtained in S2 to obtain a mica slurry mixed at 100 rpm for 5 min. After adding 135 g of the finished silicone resin, stir at 200 rpm for 5 min to obtain a mica insulation product slurry. Among them, the preparation method of the silicone resin: Add 0.05 g of diethylenetriamine, 18 g of FM-7721 modified hydroxy siloxane and 32 g of methylphenyl silicone resin to the reaction kettle, pre-react at 65 °C for 120 s, cool down to 4 °C and then add 49.6 g of methanol, stir at 80 rpm for 10 min, add 0.15 g of diethylenetriamine, and stir at 60 rpm for 2 min to obtain the finished silicone resin;

[0043] S4. Inject the mica insulation product slurry in S3 into the mold, heat the mold to 75 °C, and dry for 60 min to remove the methanol solvent in the mica insulation product slurry;

[0044] S5. Adopt a four-step hot pressing forming method to obtain a semi-finished mica / organic silicon composite mica plate. The four-step hot pressing forming method is as follows: In the first-step hot pressing forming, the hot pressing conditions are that the platen temperature is 80 °C, the pressure is 0.25 Mpa, the duration is 60 s, and the deflation time is 2 s; In the second-step hot pressing forming, the hot pressing conditions are that the platen temperature is 135 °C, the pressure is 0.5 Mpa, the duration is 100 s, and the deflation time is 2 s. In the third-step hot pressing forming, the hot pressing conditions are that the platen temperature is 180 °C, the pressure is 0.8 Mpa, and the duration is 150 s; In the fourth-step hot pressing forming, the hot pressing conditions are that the platen temperature is 120 °C, the pressure is 0.5 Mpa, and the duration is 60 s to obtain a semi-finished mica composite cover;

[0045] S6. Heat the semi-finished mica insulation product to 90 °C at a heating rate of 1.5 °C / min, maintain it for 90 min, and naturally cool to room temperature to obtain the finished mica composite cover.

[0046] The method for the integrally cast and hot-pressed forming of the special-shaped mica slurry applicable to three-dimensional solid modeling for the mica cover plate 2 is the same as that for the integrally cast and hot-pressed forming of the special-shaped mica slurry applicable to three-dimensional solid modeling for the mica composite cover 1, and only the corresponding forming mold needs to be replaced.

[0047] The advantages of the first preparation method of the mica composite cover 1 and the mica cover plate 2: It can industrially mass-produce the upper cover of the power battery pack, which is beneficial to reducing the overall production cost. And the density of the mica composite cover 1 and the mica cover plate 2 is 2.11 - 2.15 g / cm 3 。

[0048] Advantages of the second preparation method of mica composite cover 1 and mica cover plate 2: The upper cover of the power battery pack prepared has good mechanical properties, protection performance, flame retardant and fire prevention performance, and insulation and anti-electric breakdown performance. The lithium battery prepared with the upper cover of the power battery pack in this application can effectively improve the overall thermal runaway protection performance of the lithium battery and reduce the mass of the overall battery pack.

[0049] The fixed connection method between mica composite cover 1 and mica cover plate 2 is hot pressing composite connection or glue bonding.

[0050] When the fixed connection method between mica composite cover 1 and mica cover plate 2 is hot pressing composite connection, its advantages are: it is convenient for industrial production of the upper cover of the power battery pack and reduces the overall production cost; in addition, using the hot pressing method to produce the upper cover of the power battery pack can improve the flatness of the surface of the upper cover of the power battery pack.

[0051] When the fixed connection method between mica composite cover 1 and mica cover plate 2 is glue bonding, the glue used is preferably hot melt adhesive, and its advantages are: when the power battery has a thermal runaway and generates hot air flow, the hot melt adhesive between the mica cover plate and the mica composite cover becomes more fluid after being heated, which can make the hot air flow more easily break through the mica cover plate and release the hot air flow to the outside, delaying the time of series burning or even explosion between power batteries and further improving the thermal runaway protection safety performance of the power battery pack.

[0052] Reference Figure 1 and Figure 2 , a number of counterbores 10 formed by penetrating the upper and lower surfaces or integrally formed on the mica composite cover 1 are composed of limit mounting holes 101 and pressure relief holes 102. The hole area formed by the vertical projection of the limit mounting hole 101 is 1.05 - 1.20 times the hole area formed by the vertical projection of the pressure relief hole 102, and the shape of the vertical projection of the limit mounting hole 101 and the shape of the vertical projection of the pressure relief hole 102 are similar figures. That is, the mica cover plate 2 is fixedly connected to the limit mounting hole 101 of the mica composite cover 1 by hot pressing or gluing. In order for the hot air flow generated by the thermal runaway of the battery pack to effectively break through the mica cover plate 2, the hole area formed by the vertical projection of the limit mounting hole 101 is 1.08 - 1.12 times the hole area formed by the vertical projection of the pressure relief hole 102.

[0053] The depth of the limiting mounting hole 101 is equal to 0.06 - 0.30 times the thickness of the mica composite cover 1. The thickness of the mica composite cover 1 is 0.8 - 2.5 mm. Preferably, the thickness of the mica composite cover 1 is 1.98 - 2.02 mm, which can ensure the bending strength of the overall upper cover of the power battery pack. When the thickness of the mica composite cover 1 is 1.98 - 2.02 mm, the depth of the limiting mounting hole 101 is 0.15 - 0.16 mm, which can make the hot air flow more easily break through the mica cover plate and release the hot air flow to the outside, delaying the time of series burning or even explosion between power batteries, and further improving the thermal runaway protection safety performance of the power battery pack.

[0054] In specific test scheme 1, the mica composite cover 1 is made by hot pressing and bending 26 pieces of P506 type mica paper (the thickness of P506 type mica paper is 0.075 - 0.080 mm) sold normally by Zhejiang Rongtai Electric Appliance Co., Ltd. into a mica substrate with a thickness of 2.00 ± 0.02 mm, and then machining the mica substrate to form three spaced counterbores 10, thus obtaining the mica composite cover 1, and the depth of the limiting mounting hole 101 in the counterbore 10 is 0.15 mm. The hole area formed by the vertical projection of the limiting mounting hole 101 is 1.05 times the hole area formed by the vertical projection of the pressure relief hole 102. Specifically, the hole area formed by the vertical projection of the pressure relief hole 102 is 36 cm 2 . The mica cover plate 2 is made by hot pressing and cutting two pieces of P506 type paper mica (the thickness of P506 type mica paper is 0.075 - 0.080 mm), with a thickness of 0.15 - 0.16 mm. The mica composite cover 1 and the mica cover plate 2 are connected by hot pressing and compounding, and the hot pressing conditions are hot pressing for 30 s at 120 °C / hot pressing pressure of 50 N.

[0055] The difference between specific test scheme 2 and specific test scheme 1 is that: the hole area formed by the vertical projection of the limiting mounting hole 101 is 1.08 times the hole area formed by the vertical projection of the pressure relief hole 102.

[0056] The difference between specific test scheme 3 and specific test scheme 1 is that: the hole area formed by the vertical projection of the limiting mounting hole 101 is 1.12 times the hole area formed by the vertical projection of the pressure relief hole 102.

[0057] The difference between specific test scheme 4 and specific test scheme 1 is that: the hole area formed by the vertical projection of the limiting mounting hole 101 is 1.15 times the hole area formed by the vertical projection of the pressure relief hole 102.

[0058] The difference between specific test scheme 5 and specific test scheme 1 is that: the hole area formed by the vertical projection of the limiting mounting hole 101 is 1.20 times the hole area formed by the vertical projection of the pressure relief hole 102.

[0059] The difference between the specific test plan 6 and the specific test plan 1 is that the hole area formed by the vertical projection of the limit mounting hole 101 is 1.25 times the hole area formed by the vertical projection of the pressure relief hole 102.

[0060] The difference between the specific test plan 7 and the specific test plan 1 is that the hole area formed by the vertical projection of the limit mounting hole 101 is 1.03 times the hole area formed by the vertical projection of the pressure relief hole 102.

[0061] The difference between the specific test plan 8 and the specific test plan 1 is that the mica composite cover 1 is formed by one-piece casting and hot pressing of special-shaped mica slurry suitable for three-dimensional modeling prepared by Zhejiang Rongtai Electric Appliance Co., Ltd. The mica cover plate 2 is formed by one-piece casting and hot pressing of special-shaped mica slurry suitable for three-dimensional modeling prepared by Zhejiang Rongtai Electric Appliance Co., Ltd. The mica composite cover 1 and the mica cover plate 2 are bonded by hot melt adhesive (Lubrizol TPU UB310, USA).

[0062] Carry out a simulated air flow breakthrough test on the upper cover of the power battery pack in the specific test plans 1-8: Seal and connect the upper cover of the power battery pack to the opening end of the test reactor with glue, gradually introduce nitrogen at 25°C into the reactor to increase the pressure. When the air flow breaks through the mica cover plate, record the air flow pressure value P d , and the air pressure Pd is the air flow failure threshold of the upper cover of this power battery pack. Repeat the above operation to test and obtain three groups of data: P d1 , P d2 , P d3 , and take the average value P d平 as the air flow failure threshold of the upper cover of the power battery pack in the specific test plan. P d平 = (P d1 + P d2 + P d3 ) / 3. Industry common sense: The hot air flow pressure released by battery thermal runaway is above 2 MPa.

[0063] Table 1 is the air flow failure threshold parameter table of the upper cover of the power battery pack in the specific test plans 1-8

[0064]

[0065] Carry out a simulated air flow breakthrough test on the upper cover of the power battery pack in the specific test plan 8: Seal and connect the upper cover of the power battery pack to the opening end of the test reactor with glue, gradually introduce nitrogen at 60 / 80 / 120°C into the reactor to increase the pressure. When the air flow breaks through the mica cover plate, record the air flow pressure value. When the nitrogen is introduced at 60°C and the air flow breaks through the mica cover plate, the air flow pressure value is 0.38 MPa. When the nitrogen is introduced at 80°C and the air flow breaks through the mica cover plate, the air flow pressure value is 0.26 MPa. When the nitrogen is introduced at 120°C and the air flow breaks through the mica cover plate, the air flow pressure value is 0.13 MPa.

[0066] In summary, the upper cover of the power battery pack in this application can ensure the thermal runaway protection performance of the power battery pack while reducing the overall mass and assembly cost of the power battery pack, facilitating the meeting of the lightweight design requirements of the power battery pack.

[0067] The embodiments of this specific implementation manner are all preferred embodiments of this application, and do not limit the protection scope of this application accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A power battery pack cover, characterized in that: It comprises a mica composite cover body (1) and a mica cover plate (2); the mica composite cover body (1) is provided with a plurality of countersunk holes (10) penetrating the upper and lower surfaces; and the mica cover plate (2) is fixedly connected to the countersunk holes (10) of the mica composite cover body (1).

2. The power battery pack upper cover according to claim 1, characterized in that: The mica composite cover (1) comprises a high-strength earthquake-resistant mica straight plate (11) and a high-strength earthquake-resistant mica folded edge (12), wherein the high-strength earthquake-resistant mica folded edge (12) is integrally formed on the side surface of the high-strength earthquake-resistant mica straight plate (11) in the length direction.

3. The power battery pack upper cover according to claim 1, characterized in that: The thickness of the mica composite cover (1) is 0.8-2.5 mm; the countersunk hole (10) is composed of a position-limiting installation hole (101) and a pressure relief hole (102); the vertical projection area of ​​the position-limiting installation hole (101) is 1.05-1.20 times the vertical projection area of ​​the pressure relief hole (102); and the depth of the position-limiting installation hole (101) is equal to 0.06-0.30 times the thickness of the mica composite cover (1).

4. The power battery pack upper cover according to claim 3, characterized in that: The thickness of the mica composite cover (1) is 1.98-2.02 mm; the depth of the position-limiting installation hole (101) is 0.15-0.16 mm; and the vertical projection area of ​​the position-limiting installation hole (101) is 1.08-1.12 times the vertical projection area of ​​the pressure relief hole (102).

5. The power battery pack upper cover according to claim 1, characterized in that: The method for fixing and connecting the mica cover plate (2) and the countersunk hole (10) of the mica composite cover body (1) is hot pressing composite connection.

6. The power battery pack upper cover according to claim 1, characterized in that: The mica cover plate (2) and the countersunk hole (10) of the mica composite cover body (1) are fixedly connected by gluing.

7. A power battery pack upper cover according to claim 6, characterized in that: The mica cover plate (2) is fixedly connected to the countersunk hole (10) of the mica composite cover body (1) by means of hot melt adhesive.

8. The power battery pack upper cover according to claim 3, characterized in that: The thickness of the mica cover plate (2) is equal to the depth of the position-limiting mounting hole (101), that is, the upper surface of the mica cover plate (2) is flush with the upper surface of the mica composite cover body (1).

9. The power battery pack upper cover according to claim 8, characterized in that: The mica composite cover body (1) is made by hot pressing and bending ten to twenty-six sheets of P506 mica paper; the mica cover plate (2) is made by hot pressing and cutting one to four sheets of P506 mica paper; the thickness of the P506 mica paper is 0.075-0.080 mm.

10. The power battery pack upper cover according to claim 1, characterized in that: The mica composite cover (1) is formed by integral casting and hot pressing of a special-shaped mica slurry suitable for three-dimensional modeling prepared by Zhejiang Rongtai Electrical Equipment Co., Ltd.; the mica cover plate (2) is also formed by integral casting and hot pressing of a special-shaped mica slurry suitable for three-dimensional modeling prepared by Zhejiang Rongtai Electrical Equipment Co., Ltd.

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