Battery monomer and battery pack

Abstract

The utility model relates to the technical field of new energy batteries, and discloses a single battery and a battery pack, the single battery has a first direction, a second direction and a third direction which are mutually vertical pairwise, and the single battery comprises a shell, a battery pack and a battery pack, the cover plate is fixedly connected with the shell and covers the accommodating cavity; the electrode assembly is arranged in the accommodating cavity; the insulating film is arranged in the containing cavity, wraps the electrode assembly and comprises a bottom film opposite to the cover plate in the first direction and a side film connected with the bottom film, a plurality of convex parts are arranged on the side, facing the shell in the second direction or the third direction, of the side film at intervals, and concave parts are formed between the convex parts of the side film; an exhaust channel extending in the first direction is defined by the convex part, the concave part and the shell. When the single battery is in thermal runaway, the exhaust channel can exhaust the gas gathered at the cover plate to the explosion-proof valve at the bottom of the shell along the first direction for rapid pressure relief, so that the risk of cover plate burst is reduced, and the safety of the single battery is improved.

Description

Technical Field

[0001] This utility model relates to the field of new energy battery technology, and in particular to a battery cell and battery pack. Background Technology

[0002] Lithium-ion batteries can experience thermal runaway when subjected to impact damage or internal short circuits. To improve the safety of lithium-ion batteries, explosion-proof valves are installed. When thermal runaway causes an increase in internal pressure, the explosion-proof valve will rupture to quickly reduce the internal pressure of the lithium-ion battery.

[0003] A typical lithium-ion battery includes a casing, a top cover, an insulating film, electrode assemblies, and an explosion-proof valve. The electrode assemblies are housed within the casing, the top cover seals the casing, and the insulating film encases the electrode assemblies to insulate them from the casing. The explosion-proof valve is located on either the top cover or the casing. The design of placing the explosion-proof valve on the top cover, which has terminals, is prone to dual failures of electrical insulation and thermal runaway in the event of cell misuse or extreme conditions. With increasingly stringent safety requirements for power batteries, thermal-electric separation designs are becoming more common to mitigate the risk of these dual failures.

[0004] Typical thermoelectric separation designs eliminate the explosion-proof valve on the top cover, instead placing it at the bottom of the casing. This ensures that electrical connections and thermal runaway emissions do not interfere with each other in the event of cell misuse. However, with the explosion-proof valve on the aluminum casing, when thermal runaway occurs, the gas rises to the top cover at high temperatures. The increased internal pressure at the top cover can cause it to rupture, and the high-temperature gas erupting from the weak point could ignite other cells, expanding the thermal runaway range and compromising the safety of the lithium-ion battery. Utility Model Content

[0005] The purpose of this invention is to provide a single battery cell to solve the problem of top cover cracking during thermal runaway in existing lithium-ion batteries; this invention also provides a battery pack using this single battery cell.

[0006] To achieve the above objectives, this utility model provides a battery cell having a first direction, a second direction, and a third direction that are mutually perpendicular to each other. The battery cell includes:

[0007] The outer casing has a receiving cavity;

[0008] A cover plate is fixedly connected to the outer shell and seals the receiving cavity;

[0009] Electrode assembly is disposed in the receiving cavity;

[0010] An insulating film is disposed in the receiving cavity, the insulating film encapsulates the electrode assembly, the insulating film includes a bottom film disposed opposite to the cover plate along the first direction and a side film connected to the bottom film, the side film is provided with a plurality of protrusions spaced apart along the second direction or the third direction towards the outer shell, the side film forms a recess between each of the protrusions, and the protrusions, the recesses and the outer shell enclose an exhaust channel extending along the first direction.

[0011] In some embodiments, the recess is provided with a first weak portion.

[0012] In some embodiments, the recess is provided with a first groove, the first groove extending along the first direction or the second direction, the first groove forming the first weak portion.

[0013] In some embodiments, the protrusion includes an elongated boss that extends along the first direction, and the sidewall membrane forms the recess between two adjacent elongated bosses.

[0014] In some embodiments, the elongated protrusion has a recessed groove on the side near the electrode assembly, the elongated protrusion includes a first sidewall facing the housing along the second direction or the third direction and a second sidewall connecting the first sidewall and the recess, the second sidewall also having a second weak portion.

[0015] In some embodiments, the second sidewall is provided with a second groove, the second groove extending along the first direction or the second direction, and the second groove forming the second weak portion.

[0016] In some embodiments, the second sidewall is further provided with vents, which penetrate the second sidewall along the second direction or the third direction.

[0017] In some embodiments, the protrusion includes a plurality of circular protrusions arranged in an array, and the sidewall membrane forms the recess between two adjacent circular protrusions.

[0018] In some embodiments, the cover plate includes a top cover sheet and a lower insulating member connected to the top cover sheet. The top cover sheet is fixedly connected to the housing. The lower insulating member is disposed on the side of the top cover sheet facing the electrode assembly along the first direction. The lower insulating member has a first port, a second port, and an air passage. The first port is located on the side of the side membrane facing the electrode assembly, the second port is located on the side of the side membrane facing the housing, and the air passage connects the first port and the second port.

[0019] This utility model also provides a battery pack, including the battery cells described in any of the above technical solutions.

[0020] Compared with the prior art, the battery cell and battery pack of this utility model embodiment have the following advantages: the side film of the insulating film has a protrusion and a concave part on the side facing the outer shell, and the protrusion and concave part and the outer shell enclose to form an exhaust channel. When the battery cell thermally runs away, the exhaust channel can discharge the gas accumulated at the cover plate along the first direction to the explosion-proof valve at the bottom of the outer shell for rapid pressure relief, reducing the risk of the cover plate bursting and improving the safety of the battery cell. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a single battery cell of this utility model;

[0022] Figure 2 yes Figure 1 A schematic diagram of the insulating film structure of a single battery cell;

[0023] Figure 3 yes Figure 2 A partially enlarged schematic diagram of the insulating film;

[0024] Figure 4 yes Figure 2 A schematic diagram of the structure when the first notch of the insulating film extends along the second direction;

[0025] Figure 5 yes Figure 2 A schematic diagram of the structure when the protrusion of the insulating film is a long strip-shaped boss;

[0026] Figure 6 yes Figure 5 A partially enlarged schematic diagram of the insulating film;

[0027] Figure 7 yes Figure 6 A magnified schematic diagram of the insulating film at point A;

[0028] Figure 8 yes Figure 6 A partial top view of the insulating film;

[0029] Figure 9 yes Figure 1 A schematic diagram of the assembly of the insulating film of the battery cell and the lower insulating component of the cover plate;

[0030] Figure 10 yes Figure 9 A partially enlarged schematic diagram of the lower insulating component of a single battery cell.

[0031] In the figure, 1 is the outer shell, 11 is the receiving cavity, 2 is the cover plate, 21 is the top cover plate, 22 is the lower insulating component, 23 is the first opening, 24 is the second opening, 25 is the air passage, 3 is the electrode assembly, 4 is the insulating film, 41 is the bottom film, 42 is the side film, 43 is the protrusion, 44 is the concave part, 441 is the first notch, 5 is the first weak part, 6 is the elongated boss, 61 is the first side wall, 62 is the second side wall, 621 is the second notch, 63 is the vent, 64 is the groove, 7 is the second weak part, 8 is the circular boss, 9 is the exhaust passage, Z is the first direction, Y is the second direction, and X is the third direction. Detailed Implementation

[0032] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this utility model, but are not intended to limit its scope.

[0033] A preferred embodiment of a battery cell of this utility model is as follows: Figures 1 to 10 As shown, the battery cell includes a housing 1, a cover plate 2, an electrode assembly 3, and an insulating film 4. The housing 1 has a receiving cavity 11. The electrode assembly 3 and the insulating film 4 are both disposed in the receiving cavity 11. The cover plate 2 is fixedly connected to the housing 1 and seals the receiving cavity 11 to protect the electrode assembly 3 and the insulating film 4 inside the receiving cavity 11.

[0034] Each battery cell has a first direction Z, a second direction Y, and a third direction X, all of which are perpendicular to each other. In this embodiment, the battery cell is a square lithium battery. The first direction Z is the height direction of the battery cell, and one of the second direction Y and the third direction X is the width direction and the other is the thickness direction of the battery cell, respectively. The first direction Z, the second direction Y, and the third direction X are perpendicular to each other.

[0035] An insulating film 4 wraps around the electrode assembly 3 to insulate and isolate the outer casing 1 and the electrode assembly 3, thereby improving the insulation of the battery cell. The insulating film 4 includes a bottom film 41 and side films 42. The bottom film 41 is disposed opposite to the cover plate 2 along the first direction Z. The side films 42 are connected to the bottom film 41. There are four side films 42 in total, and each of the four side films 42 corresponds to one of the four sides of the battery cell. The bottom film 41 and the four side films 42 form an insulating film 4 with an opening at the top to wrap the electrode assembly 3.

[0036] A plurality of protrusions 43 are spaced apart on the side membrane 42. The protrusions 43 are located on the side of the side membrane 42 facing the outer shell 1 along the second direction Y or the third direction X, that is, the protrusions 43 are located on the outer wall surface of the side membrane 42. The side membrane 42 forms recesses 44 between each protrusion 43, so that the protrusions 43 and recesses 44 are alternately arranged. In this embodiment, the protrusions 43 and recesses 44 can be provided on only one side membrane 42, or they can be provided on two opposite side membranes 42 or on all four side membranes 42.

[0037] In some embodiments, the protrusion 43 is a solid structure, which provides greater strength and better support for the exhaust channel 9, ensuring its stability in the event of thermal runaway of the battery cell. In some embodiments, the protrusion 43 is a contoured structure with an internal cavity, which can better reduce the weight of the insulating film 4 and lower the cost of the battery cell.

[0038] During cyclic use, the internal pressure of a battery cell increases, causing the protrusion 43 to abut against the inner wall of the outer casing 1. Adjacent protrusions 43 and recesses 44, together with the outer casing 1, form an exhaust channel 9 extending along the first direction Z. When a battery cell experiences thermal runaway, the gas accumulated at the cover plate 2 can be discharged through the exhaust channel 9 along the first direction Z to the explosion-proof valve on the side of the outer casing 1 away from the cover plate 2, rapidly reducing the internal pressure of the battery casing and minimizing the risk of the cover plate 2 bursting.

[0039] In some embodiments, the height of the protrusion 43 is defined as H, and the width of the recess 44 is defined as D, where 0.1mm ≤ H ≤ 5mm and 0.2mm ≤ D ≤ 15mm. The height H of the protrusion 43 is equal to the distance between the recess 44 and the outer casing 1, and the width of the recess 44 is equal to the distance between two adjacent protrusions 43. When 0.1mm ≤ H ≤ 5mm and 0.2mm ≤ D ≤ 15mm, the cross-sectional area of ​​the exhaust channel 9 perpendicular to the first direction Z can be guaranteed, increasing the gas release efficiency.

[0040] The insulating film 4 of the battery cell has a protrusion 43 and a recess 44 on the side facing the outer casing 1. The protrusion 43 and the recess 44 together with the outer casing 1 form an exhaust channel 9. When the battery cell experiences thermal runaway, the exhaust channel 9 can discharge the gas accumulated at the cover plate 2 along the first direction Z to the explosion-proof valve at the bottom of the outer casing 1 to quickly relieve pressure, reduce the risk of the cover plate 2 bursting, and improve the safety of the battery cell.

[0041] In some embodiments, the recess 44 is provided with a first weak portion 5.

[0042] like Figures 2 to 8As shown, the thickness of the first weak part 5 is less than the overall thickness of the insulating film 4. When the battery cell experiences thermal runaway, the high-pressure gas can tear the first weak part 5 and directly enter the exhaust channel 9, and then be discharged to the explosion-proof valve area through the exhaust channel 9, achieving the effect of rapid pressure relief.

[0043] In some embodiments, the recess 44 is provided with a first groove 441, which extends along a first direction Z or a second direction Y, and forms a first weak portion 5.

[0044] A first notch 441 extending along either the first direction Z or the second direction Y forms the first weak portion 5. The first notch 441 can be formed by cutting or pressing, simplifying the formation of the first weak portion 5. In other embodiments, the overall thickness of the recess 44 can be less than that of the protrusion 43, in which case the recess 44 as a whole forms the first weak portion 5.

[0045] In some embodiments, the protrusion 43 includes an elongated protrusion 6 that extends along a first direction Z, and the side membrane 42 forms a recess 44 between two adjacent elongated protrusions 6.

[0046] like Figure 5 , Figure 6 , Figure 7 and Figure 8 As shown, the protrusion 43 is an elongated protrusion 6, which extends along the first direction Z. The elongated protrusion 6 has a good guiding effect on the discharge of high-pressure gas, ensuring that the high-pressure gas is discharged to the explosion-proof valve area along the first direction Z. Optionally, the elongated protrusion 6 can be a whole protrusion extending along the first direction Z, or it can be a number of small protrusions extending along the first direction Z and spaced apart.

[0047] In some embodiments, the elongated protrusion 6 has a groove 64 recessed into the housing 1 on the side near the electrode assembly 3. The elongated protrusion 6 includes a first sidewall 61 facing the housing 1 along the second direction Y or the third direction X and a second sidewall 62 connecting the first sidewall 61 and the recess 44. The second sidewall 62 also has a second weak portion 7.

[0048] like Figure 6 , Figure 7 and Figure 8 As shown, the first sidewall 61 is the sidewall of the elongated protrusion 6 that contacts the outer casing 1, and the second sidewall 62 is the sidewall that is perpendicularly connected to the recess 44. The recess 64 makes the elongated protrusion 6 a cavity. A second weak part 7 is provided on the second sidewall 62. When the battery cell experiences thermal runaway, the high-pressure gas can tear the insulating film 4 through the second weak part 7, further rapidly releasing pressure.

[0049] In some embodiments, the second sidewall 62 is provided with a second notch 621, which extends along a first direction Z or a second direction Y, and forms a second weak portion 7.

[0050] The second notch 621 can be formed by cutting and pressing, simplifying the formation of the second weak part 7. In other embodiments, the overall thickness of the second sidewall 62 can be made smaller than that of the first sidewall 61, in which case the second sidewall 62 as a whole forms the first weak part 5.

[0051] In some embodiments, the second sidewall 62 is further provided with an air hole 63, which penetrates the second sidewall 62 along the second direction Y or the third direction X.

[0052] like Figure 6 and Figure 7 As shown, the vent 63 penetrates the second sidewall 62 of the elongated protrusion 6. The vent 63 can accelerate the release speed of high pressure gas. When the vent 63 is insufficient to release pressure quickly, the high pressure gas can further tear the insulating film 4 through the vent 63.

[0053] In some embodiments, the protrusion 43 includes a plurality of circular protrusions 8, which are arranged in an array, and the side membrane 42 forms a recess 44 between two adjacent circular protrusions 8.

[0054] like Figure 2 , Figure 3 and Figure 4 As shown, the circular boss 8 forms a protrusion 43. The contact area between the circular boss 8 and the outer shell 1 is small, which can increase the area of ​​the exhaust channel 9 and increase the exhaust efficiency. In this embodiment, the circular bosses 8 are arranged in an array. In other embodiments, the circular bosses 8 may also be arranged irregularly.

[0055] In some embodiments, the cover plate 2 includes a top cover plate 21 and a lower insulating member 22 connected to the top cover plate 21. The top cover plate 21 is fixedly connected to the outer shell 1. The lower insulating member 22 is disposed on the side of the top cover plate 21 facing the electrode assembly 3 along the first direction Z. The lower insulating member 22 is provided with a first opening 23, a second opening 24 and an air passage 25. The first opening 23 is located on the side of the side membrane 42 facing the electrode assembly 3, the second opening 24 is located on the side of the side membrane 42 facing the outer shell 1, and the air passage 25 connects the first opening 23 and the second opening 24.

[0056] like Figure 9 and Figure 10 As shown, the lower insulating member 22 of the cover plate 2 is provided with a first port 23, a second port 24 and a gas passage 25. When the battery cell thermally runs away, the gas accumulates at the cover plate 2 and can enter the gas passage 25 through the first port 23 and then enter the exhaust passage 9 through the second port 24, thereby accelerating the gas release rate.

[0057] This utility model also provides a preferred embodiment of a battery pack, including a battery cell. The specific structure of the battery cell is the same as that of the battery cell described in any of the above embodiments, and will not be repeated here.

[0058] In summary, this utility model embodiment provides a battery cell and a battery pack, wherein the side film of the insulating film has a protrusion and a recess on the side facing the outer shell, and the protrusion and recess together with the outer shell form an exhaust channel. When the battery cell experiences thermal runaway, the exhaust channel can discharge the gas accumulated at the cover plate along the first direction to the explosion-proof valve at the bottom of the outer shell for rapid pressure relief, reducing the risk of the cover plate bursting and improving the safety of the battery cell.

[0059] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present utility model, and these improvements and substitutions should also be considered within the protection scope of the present utility model.

Claims

1. A battery cell, characterized in that, The battery cell has a first direction, a second direction, and a third direction that are perpendicular to each other. The battery cell includes: The outer casing has a receiving cavity; A cover plate is fixedly connected to the outer shell and seals the receiving cavity; Electrode assembly is disposed in the receiving cavity; An insulating film is disposed in the receiving cavity, the insulating film encapsulates the electrode assembly, the insulating film includes a bottom film disposed opposite to the cover plate along the first direction and a side film connected to the bottom film, the side film is provided with a plurality of protrusions spaced apart along the second direction or the third direction towards the outer shell, the side film forms a recess between each of the protrusions, and the protrusions, the recesses and the outer shell enclose an exhaust channel extending along the first direction.

2. The battery cell according to claim 1, characterized in that, The recess is provided with a first weak part.

3. The battery cell according to claim 2, characterized in that, The recess is provided with a first groove, which extends along the first direction or the second direction, and forms the first weak part.

4. The battery cell according to any one of claims 1-3, characterized in that, The protrusion includes an elongated protrusion that extends along the first direction, and the side membrane forms the recess between two adjacent elongated protrusions.

5. The battery cell according to claim 4, characterized in that, The elongated protrusion has a groove recessed into the housing on the side near the electrode assembly. The elongated protrusion includes a first sidewall facing the housing along the second direction or the third direction and a second sidewall connecting the first sidewall and the recess. The second sidewall also has a second weak portion.

6. The battery cell according to claim 5, characterized in that, The second sidewall is provided with a second groove, which extends along the first direction or the second direction, and forms the second weak part.

7. The battery cell according to claim 5, characterized in that, The second sidewall is also provided with air holes, which penetrate the second sidewall along the second direction or the third direction.

8. The battery cell according to any one of claims 1-3, characterized in that, The protrusion includes a plurality of circular protrusions, which are arranged in an array, and the side membrane forms the recess between two adjacent circular protrusions.

9. The battery cell according to any one of claims 1-3, characterized in that, The cover plate includes a top cover sheet and a lower insulating member connected to the top cover sheet. The top cover sheet is fixedly connected to the outer shell. The lower insulating member is disposed on the side of the top cover sheet facing the electrode assembly along the first direction. The lower insulating member has a first port, a second port, and an air passage. The first port is located on the side of the side membrane facing the electrode assembly, the second port is located on the side of the side membrane facing the outer shell, and the air passage connects the first port and the second port.

10. A battery pack, characterized in that, Includes the battery cell described in any one of claims 1-9.

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