Pouch battery cell

Abstract

The application relates to the technical field of batteries, in particular to a soft package battery cell, which comprises a pole piece assembly and an outer film, the outer film is wrapped outside the pole piece assembly, and the outer film extends to the side of the pole piece assembly which is not formed with a pole lug in a direction perpendicular to the thickness direction of the pole piece assembly to form a side packaging edge part; the side packaging edge part comprises a non-pressing part and a two-seal pressing part which are connected, the non-pressing part is arranged close to the pole piece assembly, the two-seal pressing part is formed with an auxiliary pressure relief notch, the non-pressing part is formed with a gas buffer protruding area which extends towards the two-seal pressing part, and a tearing area which extends along the length direction of the side packaging edge part and / or the width direction of the side packaging edge part is formed between the gas buffer protruding area and the auxiliary pressure relief notch. It can be seen that the auxiliary pressure relief notch and the gas buffer protruding area of the side part are designed, directional and constant pressure relief of the side part is realized, and the risk that fire combustion is caused by pressure relief from the pole lug side can be avoided.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a pouch cell. Background Technology

[0002] Currently, pouch batteries include not only lithium iron phosphate (LFP) batteries but also ternary and manganese-based systems. LFP batteries produce less gas, and pressure relief is achieved by adjusting the sealing strength of the aluminum-plastic film. However, because pouch cells now include LFP, ternary, and manganese-based systems, their gas production is higher, making safety testing difficult. Simply adjusting the aluminum-plastic film strength may lead to electrolyte leakage. Many manufacturers currently use pressure relief ports and valves on the tab side to achieve targeted early pressure relief, prompting the cell to release gas in advance. However, the pressure relief valve is located in the middle of the tab. During thermal runaway, the organic matter and flammable gases generated during gas release can easily ignite the cell due to short-circuit arcing at the tab, posing a significant safety risk. Therefore, how to achieve targeted early pressure relief without compromising cell safety is a pressing issue for pouch cells. Utility Model Content

[0003] The purpose of this application is to provide a soft-pack battery cell that, to a certain extent, solves the technical problem in the prior art of how to achieve directional early pressure relief without affecting the safety of the battery cell.

[0004] This application provides a pouch cell, including: an electrode assembly and an outer film; wherein, the outer film covers the outside of the electrode assembly and extends along a direction perpendicular to the thickness direction of the electrode assembly to the side of the electrode assembly where no tabs are formed, to form a side encapsulation edge. The side-encapsulation edge includes an unpressed portion and a double-sealed portion connected together. The unpressed portion is disposed close to the electrode assembly. The double-sealed portion has an auxiliary pressure relief notch. The unpressed portion has a gas buffer protrusion extending toward the double-sealed portion. A tearing area extending along the length direction and / or the width direction of the side-encapsulation edge is formed between the gas buffer protrusion and the auxiliary pressure relief notch.

[0005] In the above technical solution, further, along the length direction of the side packaging edge, the minimum length of the tearing area is L1, and 0.5mm≤L1≤1mm.

[0006] In any of the above technical solutions, further, along the width direction of the side packaging edge, the minimum width of the tearing area is L2, and 0mm≤L2≤5mm.

[0007] In any of the above technical solutions, further, along the thickness direction perpendicular to the electrode assembly, the cross-sectional area of ​​the gas buffer protrusion is greater than or equal to the cross-sectional area of ​​the auxiliary pressure relief notch.

[0008] In any of the above technical solutions, the gas buffer protrusion area is further provided with a first bottom wall disposed away from the electrode assembly side, and the gas buffer protrusion area is provided with a first side wall disposed near the auxiliary pressure relief gap, and the first side wall and the first bottom wall are connected. The auxiliary pressure relief notch has a second bottom wall located near the electrode assembly side, and the auxiliary pressure relief notch has a second side wall located near the gas buffer protrusion area. The second side wall and the second bottom wall are connected, and the second side wall is parallel to the first side wall and the second bottom wall is parallel to the first bottom wall.

[0009] In any of the above technical solutions, the angle formed between the first sidewall and the second sidewall is α, and α ≥ 90°; The angle formed between the second bottom wall and the second bottom wall is β, and β ≥ 90°.

[0010] In any of the above technical solutions, the first bottom wall and the second bottom wall are further provided along the length direction of the side encapsulation edge.

[0011] In any of the above technical solutions, further, along the thickness direction of the electrode assembly, the projection of the auxiliary pressure relief notch is rectangular, triangular, elliptical, circular, or trapezoidal.

[0012] In any of the above technical solutions, further, along the thickness direction of the electrode assembly, the projection of the gas buffer protrusion area is rectangular, triangular, elliptical, circular, or trapezoidal.

[0013] In any of the above technical solutions, further, along the height direction of the electrode assembly, at least one side of the electrode assembly is formed with an electrode tab, and along the length direction of the electrode assembly, at least one side of the electrode assembly is provided with the side encapsulation edge portion, and each side of the side encapsulation edge portion is formed with the auxiliary pressure relief notch and the gas buffer protrusion area.

[0014] In any of the above technical solutions, further, along the length direction of the electrode assembly, both sides of the electrode assembly are provided with the side encapsulation edge portion, and each side of the side encapsulation edge portion is formed with the auxiliary pressure relief notch and the gas buffer protrusion area.

[0015] Compared with the prior art, the beneficial effects of this application are as follows: This application achieves directional and constant pressure relief on the side by designing auxiliary pressure relief notches and gas buffer protrusions on the side. It can also meet the strength requirements of the side sealing film, thus eliminating the need to repeatedly adjust the strength of the aluminum-plastic film to meet the pressure relief requirements as in the prior art. It also avoids the risk of fire caused by pressure relief from the tab side. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of a pouch cell provided in an embodiment of this application; Figure 2 for Figure 1 A magnified structural diagram at point A; Figure 3 This is another structural schematic diagram of the pouch cell provided in the embodiments of this application; Figure 4 for Figure 3 A magnified structural diagram at point B; Figure 5 This is another structural schematic diagram of the pouch cell provided in the embodiments of this application; Figure 6 for Figure 5 A magnified structural diagram at point C.

[0018] Figure label: 1-Outer membrane, 11-Side encapsulation edge, 111-Unpressed portion, 112-Secondary sealing and pressing portion, 113-Auxiliary pressure relief notch, 1131-Second bottom wall, 1132-Second side wall, 114-Gas buffer protrusion area, 1141-First bottom wall, 1142-First side wall, 2-Taper, a-Length direction of the side encapsulation edge, b-Width direction of the side encapsulation edge, c-Thickness direction of the electrode assembly. Detailed Implementation

[0019] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0020] The components of the embodiments of this application described and shown in the accompanying drawings can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of this application provided in the drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application.

[0021] Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0024] The following reference Figures 1 to 6 This application describes a pouch cell according to some embodiments.

[0025] See Figures 1 to 6 As shown, an embodiment of this application provides a soft-pack battery cell, including: an electrode assembly and an outer film 1; wherein, the outer film 1 covers the outside of the electrode assembly, and extends along a direction perpendicular to the thickness direction c of the electrode assembly to the side of the electrode assembly where no tab 2 is formed, to form a side encapsulation edge 11. It should be noted that: preferably, the outer film 1 can be an aluminum-plastic film, and this will be used as an example in the following description. Of course, it is not limited to this, and can be selected according to actual needs. The side-encapsulation edge portion 11 includes an unpressed portion 111 and a double-sealed portion 112 connected to each other. The unpressed portion 111 is disposed close to the electrode assembly. The double-sealed portion 112 has an auxiliary pressure relief notch 113. The unpressed portion 111 has a gas buffer protrusion area 114 extending toward the double-sealed portion 112. A tearing area extending along the length direction a and / or the width direction b of the side-encapsulation edge portion is formed between the gas buffer protrusion area 114 and the auxiliary pressure relief notch 113.

[0026] As described above, when thermal runaway and gas generation occur inside the pouch cell, stress concentration occurs in the gas buffer protrusion 114 after it is filled with gas. This causes tearing of the tearing area between the gas buffer protrusion 114 and the auxiliary pressure relief notch 113, thereby achieving early directional pressure relief on the side. Therefore, this application achieves directional pressure relief on the side by designing the auxiliary pressure relief notch 113 and the gas buffer protrusion 114, while also meeting the strength requirements of the side sealing film. This eliminates the need for repeated adjustments to the strength of the aluminum-plastic film required in existing technologies to meet pressure relief requirements, and also avoids the risk of fire caused by pressure relief from the tab side.

[0027] It should be noted that: the unpressed portion 111 includes an upper layer and a lower layer, and there is no hot melt adhesive between them, that is, they are not hot melt bonded together. In other words, there is a gap between them. Similarly, the gas buffer protrusion area 114 belongs to the area of ​​the unpressed portion 111. Therefore, the interior of the gas buffer protrusion area 114 is hollow and can accumulate gas, thereby creating stress concentration at the edge, which facilitates tearing of the tearing area formed between the gas buffer protrusion area 114 and the auxiliary pressure relief notch 113. The second-sealed pressing portion 112 includes an upper layer, a lower layer, and a hot melt adhesive layer between the upper and lower layers. The three are pressed together. This part is relatively existing and will not be described in detail here.

[0028] In addition, it should be noted that the electrode assembly includes the positive electrode, separator and negative electrode stacked together, which are all existing structures and will not be described in detail here.

[0029] In this embodiment, preferably, as follows: Figure 4 and Figure 6 As shown, along the length direction a of the side packaging edge, the minimum length of the tear area is L1, and 0.5mm≤L1≤1mm. Based on the structure described above, it can be seen that if the minimum length L1 of the tearing area along the length direction a of the side packaging edge is too small, the strength of the tearing area will not meet the requirements; if the minimum length L1 of the tearing area along the length direction a of the side packaging edge is too large, it will be difficult to tear the aluminum-plastic film from the tearing area when directional pressure relief is required, so L1 should be taken between 0.5mm and 1mm.

[0030] In this embodiment, preferably, as Figure 4 shown, along the width direction b of the side encapsulation edge portion, the minimum width of the tearing area is L2, and L2 = 0 mm. That is to say, the first bottom wall 1141 and the second bottom wall 1131 described below are flush. In this case, the tearing area extends along the length direction a of the side encapsulation edge portion, which can meet the strength requirements. Moreover, when directional pressure relief is required, it is easy to tear the aluminum-plastic film from the tearing area.

[0031] Of course, along the width direction b of the side encapsulation edge portion, the value of the minimum width L2 of the tearing area is not limited to the above, and can also be selected according to actual needs. For example, it can also be set that 0 mm < L2 ≤ 5 mm. That is to say, in this case, as Figure 6 shown, the first bottom wall 1141 and the second bottom wall 1131 are no longer flush, but have a certain gap along the width direction b of the side encapsulation edge portion. That is, the first bottom wall 1141 and the second bottom wall 1131 are staggered. That is to say, the first bottom wall 1141 can be arranged closer to the electrode assembly relative to the second bottom wall 1131, or the second bottom wall 1131 can be arranged closer to the electrode assembly relative to the first bottom wall 1141, which is specifically selected according to actual needs. In this embodiment, preferably, as Figure 2 、 Figure 4 and Figure 6 shown, along the thickness direction c perpendicular to the electrode assembly, the cross-sectional area of the gas buffer protrusion area 114 is greater than or equal to the cross-sectional area of the auxiliary pressure relief notch 113. According to the structure described above, the area of the gas buffer protrusion area 114 is more than 1 times the area of the auxiliary pressure relief notch 113. Stress concentration occurs after the gas buffer protrusion area 114 is inflated, realizing the tearing of the tearing area between the gas buffer protrusion area 114 and the auxiliary pressure relief notch 113, meeting the pressure relief requirements. Moreover, through testing, taking the rectangular gas buffer protrusion area 114 in this application as an example, when L1 and L2 described above meet the requirements and remain unchanged, when the area of the gas buffer protrusion area 114 is 2 times the area of the auxiliary pressure relief notch 113, the required pressure relief is 0.08 Mpa, and when the areas of the two are equal, the pressure relief is 0.16 Mpa. It can be seen that the pressure relief pressure can be adjusted by reasonably setting the ratio of the area of the gas buffer protrusion area 114 to the area of the auxiliary pressure relief notch 113, so as to meet the constant pressure relief.

[0032] In this embodiment, preferably, as Figure 4 and Figure 6As shown, the gas buffer protrusion 114 has a first bottom wall 1141 disposed away from the electrode assembly side, and the gas buffer protrusion 114 has a first side wall 1142 disposed near the auxiliary pressure relief gap 113, and the first side wall 1142 and the first bottom wall 1141 are connected. The auxiliary pressure relief notch 113 has a second bottom wall 1131 located near the electrode assembly side, and a second side wall 1132 located near the gas buffer protrusion area 114. The second side wall 1132 is connected to the second bottom wall 1131, and the second side wall 1132 is parallel to the first side wall 1142, and the second bottom wall 1131 is parallel to the first bottom wall 1141. As can be seen from the structure described above, the second sidewall 1132 is arranged parallel to the first sidewall 1142, and the second bottom wall 1131 is arranged parallel to the first bottom wall 1141. This makes it easier to control the shape and size of the tearing area between the auxiliary pressure relief notch 113 and the gas buffer protrusion area 114, which better meets the requirements and is a more reasonable design. In this embodiment, preferably, as follows: Figure 4 and Figure 6 As shown, the angle formed between the first sidewall 1142 and the second sidewall 1132 is α, and α = 90°. Similarly, the angle formed between the second bottom wall 1131 and the second bottom wall 1132 is β. Since β = α, and the range of values ​​for β is the same as the range of values ​​for α, that is, β = 90°. Based on the structure described above, setting both α and β to 90° ensures that stress concentration is easily achieved after the gas buffer protrusion 114 is inflated, thereby reducing the tearing of the tearing area between the gas buffer protrusion 114 and the auxiliary pressure relief notch 113, achieving early directional pressure relief on the side. Of course, the values ​​of α and β are not limited to these; α can also be greater than 90°, and β can also be greater than 90°, depending on the actual needs. Conversely, the values ​​of α and β are not limited to those mentioned above; for example, α can also be less than 90°, and β can also be less than 90°, depending on the actual needs.

[0033] In addition, it should be noted that the second sidewall 1132 and the first sidewall 1142 are not limited to being parallel to each other, but can also form an angle between them; the second bottom wall 1131 and the first bottom wall 1141 are not limited to being parallel to each other, but can also form an angle between them, depending on the actual needs.

[0034] In this embodiment, preferably, as follows: Figure 2 , Figure 4 and Figure 6As shown, the first bottom wall 1141 and the second bottom wall 1131 are both arranged along the length direction a of the side encapsulation edge, making the structure more regular and easier to manufacture. Of course, it is not limited to this. The first bottom wall 1141 and the second bottom wall 1131 can also form a certain angle with the side encapsulation edge 11, depending on the actual needs. In this embodiment, preferably, as follows: Figure 2 , Figure 4 and Figure 6 As shown, the projection of the auxiliary pressure relief notch 113 along the thickness direction c of the electrode assembly is rectangular, with a regular shape, which facilitates manufacturing and makes it easy to control the shape and size of the tearing area to meet strength and pressure relief requirements. Of course, it is not limited to this; the projection of the auxiliary pressure relief notch 113 along the thickness direction c of the electrode assembly can also be triangular, elliptical, circular, or trapezoidal, etc., depending on the actual needs. In this embodiment, preferably, as follows: Figure 2 , Figure 4 and Figure 6 As shown, along the thickness direction c of the electrode assembly, the projection of the gas buffer protrusion 114 is rectangular, with a regular shape, which facilitates manufacturing and makes it easy to control the shape and size of the tearing area to meet strength and pressure relief requirements. Of course, it is not limited to this; along the thickness direction c of the electrode assembly, the projection of the gas buffer protrusion 114 can also be triangular, elliptical, circular, or trapezoidal, etc., depending on the actual needs.

[0035] In addition, it should be noted that the shapes of the gas buffer protrusion 114 and the auxiliary pressure relief notch 113 are preferably matched. Of course, this is not the only option; they can also be designed according to actual needs. In this embodiment, preferably, as follows: Figure 1 As shown, along the height direction of the electrode assembly, an electrode tab 2 is formed on one side of the electrode assembly, and along the length direction of the electrode assembly, side sealing edge portions 11 are provided on both sides of the electrode assembly, and each side sealing edge portion 11 is provided with an auxiliary pressure relief notch 113 and a gas buffer protrusion area 114. As can be seen from the structure described above, when a pouch cell experiences thermal runaway, pressure can be released simultaneously from both sides of the cell in advance, improving the pressure release effect and further enhancing the safety and reliability of the pouch cell during use.

[0036] It should be noted that the electrode tab 2 is not limited to one side, but can also be output from both sides. That is to say, along the height direction of the electrode assembly, electrode tabs 2 can be output from opposite sides of the electrode assembly.

[0037] In addition, it should be noted that: not only are auxiliary pressure relief notches 113 and gas buffer protrusion areas 114 provided on both sides of the side encapsulation edge 11 of the electrode assembly, but also only on one side of the side encapsulation edge 11, the auxiliary pressure relief notches 113 and gas buffer protrusion areas 114 may be provided, depending on the actual needs.

[0038] Furthermore, it should be noted that in this embodiment, each side of the encapsulation edge 11 is provided with an auxiliary pressure relief notch 113 and a gas buffer protrusion area 114, which is a set of pressure relief structures. Of course, it is not limited to this. Multiple auxiliary pressure relief notches 113 and multiple gas buffer protrusion areas 114, which are the aforementioned multiple sets of pressure relief structures, can also be provided. The multiple sets of pressure relief structures are arranged sequentially at intervals along the length direction a of the side encapsulation edge, etc., depending on the actual needs.

[0039] In summary, the thermal runaway venting test of the soft-pack battery cell provided in this application was conducted (where various data involved were changed according to actual needs, such as: L1, L2, α, β, the shape of the auxiliary pressure relief notch 113, the shape of the gas buffer protrusion area 114, and the ratio of the areas of the auxiliary pressure relief notch 113 and the gas buffer protrusion area 114, etc.). The test results showed that when the pressure relief reaches 0.14 MPa-0.25 MPa, it is possible to tear the tearing area between the gas buffer protrusion area 114 and the auxiliary pressure relief notch 113, thus meeting the pressure relief requirements. Moreover, this pressure range is smaller than the pressure relief range in the prior art, thereby enabling early pressure relief.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A pouch cell, characterized in that, include: An electrode assembly and an outer film; wherein the outer film covers the outside of the electrode assembly and extends to the side of the electrode assembly without tabs along a direction perpendicular to the thickness direction of the electrode assembly to form a side encapsulation edge. The side-encapsulation edge includes an unpressed portion and a double-sealed portion connected together. The unpressed portion is disposed close to the electrode assembly. The double-sealed portion has an auxiliary pressure relief notch. The unpressed portion has a gas buffer protrusion extending toward the double-sealed portion. A tearing area extending along the length direction and / or the width direction of the side-encapsulation edge is formed between the gas buffer protrusion and the auxiliary pressure relief notch.

2. The soft-pack battery cell according to claim 1, characterized in that, Along the length direction of the side packaging edge, the minimum length of the tearing area is L1, and 0.5mm≤L1≤1mm.

3. The soft-pack battery cell according to claim 1, characterized in that, Along the width direction of the side packaging edge, the minimum width of the tearing area is L2, and 0mm≤L2≤5mm.

4. The soft-pack battery cell according to claim 1, characterized in that, Along the thickness direction perpendicular to the electrode assembly, the cross-sectional area of ​​the gas buffer protrusion is greater than or equal to the cross-sectional area of ​​the auxiliary pressure relief notch.

5. The soft-pack battery cell according to claim 1, characterized in that, The gas buffer protrusion area has a first bottom wall disposed away from the electrode assembly, and the gas buffer protrusion area has a first side wall disposed near the auxiliary pressure relief notch, and the first side wall and the first bottom wall are connected. The auxiliary pressure relief notch has a second bottom wall located near the electrode assembly side, and the auxiliary pressure relief notch has a second side wall located near the gas buffer protrusion area. The second side wall and the second bottom wall are connected, and the second side wall is parallel to the first side wall and the second bottom wall is parallel to the first bottom wall.

6. The soft-pack battery cell according to claim 5, characterized in that, The angle formed between the first sidewall and the second sidewall is α, and α ≥ 90°; The angle formed between the second bottom wall and the second bottom wall is β, and β ≥ 90°; and / or Both the first bottom wall and the second bottom wall are arranged along the length direction of the side encapsulation edge.

7. The soft-pack battery cell according to claim 1, characterized in that, Along the thickness direction of the electrode assembly, the projection of the auxiliary pressure relief notch is rectangular, triangular, elliptical, circular, or trapezoidal.

8. The soft-pack battery cell according to claim 1, characterized in that, Along the thickness direction of the electrode assembly, the projection of the gas buffer protrusion is rectangular, triangular, elliptical, circular, or trapezoidal.

9. The pouch cell according to any one of claims 1 to 8, characterized in that, Along the height direction of the electrode assembly, at least one side of the electrode assembly is formed with an electrode tab, and along the length direction of the electrode assembly, at least one side of the electrode assembly is provided with a side encapsulation edge portion, and each side of the side encapsulation edge portion is formed with the auxiliary pressure relief notch and the gas buffer protrusion area.

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