Battery cell and battery module

Abstract

The invention relates to the technical field of energy storage equipment, in particular to a battery cell and a battery module, and the battery cell comprises a shell, a pole group and an inner insulating film. The first end face of the shell is provided with an anode output terminal and a cathode output terminal, and an anti-explosion valve is arranged on the first side wall of the shell away from the first end face. The pole group is arranged in the shell, and the third end face of the pole group corresponds to the second end face. The inner insulating film is bent to wrap the pole group and is clamped between the pole group and the shell, the inner insulating film comprises a first part, a second part and a third part which are connected in sequence, the side part of the first part in the first direction is connected with a first pre-sealing part, the side part of the second part in the first direction is connected with a final sealing part, and the side part of the third part in the first direction is connected with a second pre-sealing part; the third end face is coated with the first pre-sealing part, the second pre-sealing part and the final sealing part, and the final sealing part is located on the outer side of the first pre-sealing part and the outer side of the second pre-sealing part. The battery module comprises a module shell and the battery cell, wherein the battery cell is arranged in the module shell.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage equipment, and in particular to a battery cell and a battery module. Background Art

[0002] In the prior art, a pressure relief mechanism such as an explosion-proof valve is usually provided on the battery cell casing. For long-blade batteries with a smaller thickness, positive and negative output terminals are generally provided at both ends of the battery cell casing in the longitudinal direction. The explosion-proof valve is generally provided at one end of the battery cell casing in the longitudinal direction, that is, the explosion-proof valve is very close to the output terminal at one end. When the temperature control component of the battery cell is abnormal and the battery cell heats up and causes thermal runaway, the explosion-proof valve will explode open and the high-temperature mixture will be quickly discharged from the explosion-proof valve. Moreover, since the output terminal is very close to the explosion-proof valve, the insulating component at the output terminal is prone to melting and failure in a local high-temperature environment, causing a short circuit between the positive and negative electrodes, further aggravating the severity of thermal runaway and causing a safety accident. Summary of the Invention

[0003] An object of the present invention is to provide a battery cell that can avoid thermal runaway escalation and has higher safety performance.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] Provided is a battery cell, comprising:

[0006] a housing having a first end face and a second end face opposite to each other along a first direction, the first end face being provided with a positive output terminal and a negative output terminal, and an explosion-proof valve being provided on a first side wall of the housing away from the first end face;

[0007] a pole group, the pole group being disposed in the housing, the pole group having a third end face, the third end face being disposed corresponding to the second end face;

[0008] An inner insulating film, the inner insulating film is bent and wrapped around the pole group, and is clamped between the pole group and the outer shell, the inner insulating film includes a first part, a second part and a third part connected in sequence, the first part is connected to a first pre-sealing part along the side of the first direction, the second part is connected to a final sealing part along the side of the first direction, the third part is connected to a second pre-sealing part along the side of the first direction, the first pre-sealing part, the second pre-sealing part and the final sealing part are all wrapped around the third end face, and the final sealing part is located on the outside of the first pre-sealing part and the second pre-sealing part.

[0009] Optionally, the first portion and the third portion are arranged opposite to each other along the thickness direction of the pole group, the thickness of the pole group is a, and along the thickness direction of the pole group, the size of the final sealing portion is b, satisfying: b≥0.4a.

[0010] Optionally, the first portion and the third portion are arranged opposite to each other along the thickness direction of the pole group, the third end face has a first side edge and a second side edge arranged opposite to each other along the thickness direction of the pole group, the final sealing portion is spaced apart from the first side edge and the second side edge, the distance between the final sealing portion and the first side edge is c, and the distance between the final sealing portion and the second side edge is d, satisfying: 0.4mm≤c≤15mm, 0.4mm≤d≤15mm.

[0011] Optionally, the third end surface further has a third side and a fourth side that are oppositely arranged, and the inner insulating film satisfies:

[0012] The first pre-sealing portion includes a first rectangular portion, one side of the first rectangular portion is located on the first side, and the other two sides of the first rectangular portion are respectively located on the third side and the fourth side;

[0013] And / or, the second pre-sealed portion includes a second rectangular portion, one side of the second rectangular portion is located on the second side, and the other two sides of the second rectangular portion are respectively located on the third side and the fourth side.

[0014] Optionally, a dimension g of the first rectangular portion along the thickness direction of the electrode group is greater than a distance c between the final sealing portion and the first side edge;

[0015] And / or, a dimension h of the second rectangular portion along the thickness direction of the pole group is greater than a distance d between the final sealing portion and the second side.

[0016] Optionally, the first direction is the length direction of the pole group, the first portion and the third portion are arranged opposite to each other along the thickness direction of the pole group, and along the width direction of the pole group, the size of the final sealing portion is consistent with the size of the third end face.

[0017] Optionally, the first portion and the third portion are arranged opposite to each other along the thickness direction of the electrode group, and the thickness of the electrode group is a, satisfying:

[0018] Along the thickness direction of the electrode group, the size of the first pre-sealed portion is e, 1 / 3a≤e≤0.8a;

[0019] And / or, along the thickness direction of the electrode group, the size of the second pre-sealed portion is f, 1 / 3a≤f≤0.8a.

[0020] Optionally, a side of the first portion facing away from the second portion is connected to a fourth portion, a side of the third portion facing away from the second portion is connected to a fifth portion, and the fourth portion and the fifth portion cover the same side wall of the pole group.

[0021] Optionally, the opening of the inner insulating film is opened corresponding to the first end surface.

[0022] Another object of the present invention is to provide a battery module that can avoid thermal runaway escalation and has higher safety performance.

[0023] To achieve this object, the present invention adopts the following technical solutions:

[0024] A battery module is provided, comprising a module shell and the above-mentioned battery cell, wherein the battery cell is arranged in the module shell.

[0025] Beneficial effects of the present invention:

[0026] The present invention provides a battery cell, comprising an outer shell, an electrode group and an inner insulating film. The outer shell has a first end face and a second end face arranged opposite to each other along a first direction, the first end face is provided with a positive output terminal and a negative output terminal, and an explosion-proof valve is provided on the first side wall of the outer shell away from the first end face. The electrode group is arranged in the outer shell, and the electrode group has a third end face, and the third end face is arranged corresponding to the second end face. The inner insulating film is bent and coated on the electrode group, and is clamped between the electrode group and the outer shell. The inner insulating film includes a first part, a second part and a third part connected in sequence, the first part is connected to a first pre-sealing part on the side along the first direction, the second part is connected to a final sealing part on the side along the first direction, and the third part is connected to a second pre-sealing part on the side along the first direction. The first pre-sealing part, the second pre-sealing part and the final sealing part are all coated on the third end face, and the final sealing part is located on the outside of the first pre-sealing part and the second pre-sealing part. By arranging the positive output terminal and the negative output terminal at the same end and arranging the explosion-proof valve on the side wall away from this end, the battery cell can greatly increase the thermoelectric distance, preventing the high-temperature fluid at the explosion-proof valve from affecting the insulating parts at the positive output terminal and the negative output terminal when the battery cell thermal runaway occurs, thereby preventing the escalation of thermal runaway caused by the melting of the insulating parts and the short circuit of the battery cell. Therefore, the battery cell has higher safety performance.

[0027] The present invention also provides a battery module comprising a module housing and the aforementioned battery cell, wherein the battery cell is disposed within the module housing. The battery module can avoid thermal runaway escalation and has higher safety performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the structure of the battery cell provided by an embodiment of the present invention;

[0029] Figure 2 is an exploded schematic diagram of a battery cell provided by an embodiment of the present invention;

[0030] Figure 3 is a schematic structural diagram of an inner insulating film provided by an embodiment of the present invention;

[0031] Figure 4 yes Figure 3 Enlarged view of point A in the middle;

[0032] Figure 5 Schematic diagram of the first coating process of the inner insulating film and the electrode group provided by an embodiment of the present invention;

[0033] Figure 6 Schematic diagram of the second coating process of the inner insulating film and the electrode group provided by an embodiment of the present invention;

[0034] Figure 7 It is a schematic diagram of the hypothetical coating of the inner insulating film and the electrode group provided by an embodiment of the present invention.

[0035] In the picture:

[0036] 1. Housing; 11. Housing body; 111. First side wall; 12. First top cover; 121. Positive output terminal; 122. Negative output terminal; 13. Second top cover; 14. Explosion-proof valve;

[0037] 2. Pole group; 21. Third end surface; 211. First side; 212. Second side;

[0038] 3. Inner insulating film; 31. First portion; 32. Second portion; 33. Third portion; 34. First pre-sealing portion; 341. First rectangular portion; 35. Final sealing portion; 36. Second pre-sealing portion; 361. Second rectangular portion; 37. Fourth portion; 38. Fifth portion; 381. Positioning hole;

[0039] 4. First patch; 5. Second patch; 6. External insulating film. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only show portions relevant to the present invention, not all of them.

[0041] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed or detachable connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention.

[0042] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0043] like Figure 1-Figure 3 As shown, the battery cell of this embodiment includes a housing 1, an electrode group 2, and an inner insulating film 3. The housing 1 has a first end face and a second end face arranged opposite each other along a first direction. The first end face is provided with a positive output terminal 121 and a negative output terminal 122. An explosion-proof valve 14 is provided on a first sidewall 111 of the housing 1, away from the first end face. The electrode group 2 is disposed within the housing 1 and has a third end face 21. The third end face 21 is arranged corresponding to the second end face, i.e., the third end face 21 and the second end face are located at the same end of the battery cell. The inner insulating film 3 is bent and wrapped around the pole group 2, and is clamped between the pole group 2 and the outer shell 1. The inner insulating film 3 includes a first part 31, a second part 32 and a third part 33 connected in sequence. The first part 31 is connected to the first pre-sealing part 34 on the side along the first direction, the second part 32 is connected to the final sealing part 35 on the side along the first direction, and the third part 33 is connected to the second pre-sealing part 36 on the side along the first direction. The first pre-sealing part 34, the second pre-sealing part 36 and the final sealing part 35 are all wrapped around the third end face 21, and the final sealing part 35 is located on the outside of the first pre-sealing part 34 and the second pre-sealing part 36.

[0044] Figure 5 As the first step of the inner insulating film 3 covering the electrode group 2, the first side wall 111 of the shell body 11 is placed on the side wall of the electrode group 2 corresponding to the second portion 32. Figure 6 As shown, the first portion 31 is attached to the large side wall of the electrode assembly 2, the third portion 33 is attached to the other large side wall of the electrode assembly 2, and the first pre-sealing portion 34 and the second pre-sealing portion 36 are bent back and forth toward the third end surface 21 and covered on the third end surface 21. Next, the final sealing portion 35 is bent upward to cover the outside of the two pre-sealing portions at the third end surface 21. It should be noted that Figure 7 This is only to show that there is a gap between the final sealing portion 35 and the first side 211 and the second side 212 of the third end surface 21. Figure 7 The state does not exist in the actual process of coating the inner insulating film 3.

[0045] Optionally, in this embodiment, the first direction is the lengthwise direction of the battery cell and electrode group 2. Optionally, the battery cell housing 1 includes a housing body 11, a first top cover 12, and a second top cover 13. The first top cover 12 is located at the first end face, and the second top cover 13 is located at the second end face. The housing body 11 has two oppositely disposed openings, and the first top cover 12 and the second top cover 13 are respectively disposed to cover these two openings. The first sidewall 111 is one of the two sidewalls of the housing body 11 disposed oppositely along the width direction of the battery cell, that is, the explosion-proof valve 14 is disposed on the sidewall with the smaller area, and not on the sidewall with the largest area.

[0046] By arranging the positive output terminal 121 and the negative output terminal 122 at the same end and arranging the explosion-proof valve 14 on the side wall away from this end, the battery cell can greatly increase the thermoelectric distance, thereby preventing the high-temperature fluid at the explosion-proof valve 14 from affecting the insulating parts at the positive output terminal 121 and the negative output terminal 122 when the battery cell thermal runaway occurs, thereby preventing the escalation of thermal runaway caused by the melting of the insulating parts and the short circuit of the battery cell, and thus the battery cell has higher safety performance.

[0047] The positive output terminal 121 and the negative output terminal 122 of the existing battery cell are respectively located on the top covers at both ends. Therefore, the internal insulating film 3 of the existing battery cell is tubular as a whole, that is, it has two openings arranged opposite to each other to correspond to the top covers at both ends of the battery cell. The internal insulating film 3 is sealed and connected to the insulating parts of the top covers at both ends to achieve overall insulation without exposure. However, the positive output terminal 121 and the negative output terminal 122 of the battery cell in this embodiment are arranged at the same end, that is, no insulating part is required at the other end. The internal insulating film 3 needs to be can-shaped as a whole, that is, it only needs to have one opening. The existing internal insulating film cannot be adapted to the battery cell of this embodiment. Therefore, this embodiment provides an internal insulating film 3 with the above-mentioned characteristics to adapt to the battery cell of this embodiment.

[0048] It can be seen that the inner insulating film 3 is bent into a can shape as a whole piece, and the first part 31 and the third part 33 are respectively covered on the two side surfaces with the largest area of the pole group 2, that is, the first part 31 and the third part 33 are arranged opposite to each other along the thickness direction of the pole group 2, and the second part 32 is correspondingly covered on the first side wall 111.

[0049] like Figure 3 and Figure 5As shown, optionally, the thickness of the pole group 2 is a, and along the thickness direction of the pole group 2, the size of the final sealing portion 35 is b, satisfying: b≥0.4a. If the width of the final sealing portion 35 is less than 0.4 times the thickness of the pole group 2, that is, the width of the final sealing portion 35 is too small, it will affect the insufficient hot-melt area between the final sealing portion 35 and the two pre-sealing portions, causing the final sealing portion 35 to be weak and easy to detach. If the width of the two pre-sealing portions is not large enough to cover the third end face 21, the failure of the final sealing portion 35 will directly lead to the exposure of the third end face 21 of the pole group 2 and insulation failure. If the two pre-sealing portions can cover the third end face 21, that is, the covering effect of the final sealing portion 35 fails, the edges of the two pre-sealing portions are prone to warping, and the ability of the two pre-sealing portions to resist external forces is reduced.

[0050] like Figure 7 As shown, optionally, the third end surface 21 has a first side 211 and a second side 212 that are oppositely disposed along the thickness direction of the electrode assembly 2. The final sealing portion 35 is spaced apart from both the first side 211 and the second side 212. The distance between the final sealing portion 35 and the first side 211 is c, and the distance between the final sealing portion 35 and the second side 212 is d, satisfying the following conditions: 0.4 mm ≤ c ≤ 15 mm, and 0.4 mm ≤ d ≤ 15 mm. That is, the final sealing portion 35 is spaced apart from the first side 211 by more than 0.4 mm, and the final sealing portion 35 is spaced apart from the second side 212 by more than 0.4 mm. The final sealing portion 35 does not fit on any side, which ensures that when there are processing errors and assembly errors, the final sealing portion 35 will still not be misplaced so that part of the final sealing portion 35 is located on the side where the first portion 31 or the third portion 33 is located. The thickness of the inner insulating film 3 at the large surface of the pole group 2 will not be increased, so that the thickness of the pole group 2 after coating will not be greater than the preset thickness, and the problems of difficulty in entering the shell and scratches and wear of the inner insulating film 3 caused by the pole group 2 exceeding the preset thickness can be avoided. And because the size b of the final sealing portion 35 along the thickness direction of the pole group 2 satisfies b≥0.4a, the sum of c and d needs to be less than or equal to 0.6a. When the two values are the same, c and d both need to be less than or equal to 0.3a. Generally, the thickness of the pole group 2 of the blade battery is less than or equal to 50mm, then c and d both need to be less than or equal to 15mm. Of course, for the battery with a pole group 2 thickness less than or equal to 35mm, its c and d both need to be less than or equal to 10.5mm. For thinner cells with a thickness of 13mm for electrode group 2, both c and d need to be less than or equal to 3.9mm.

[0051] The third end surface 21 also has a third side and a fourth side that are oppositely arranged. Figure 3 and Figure 4As shown, optionally, the first pre-sealing portion 34 includes a first rectangular portion 341, one side of the first rectangular portion 341 is located on the first side 211, and the other two sides of the first rectangular portion 341 are respectively located on the third side and the fourth side. Optionally, the second pre-sealing portion 36 includes a second rectangular portion 361, one side of the second rectangular portion 361 is located on the second side 212, and the other two sides of the second rectangular portion 361 are respectively located on the third side and the fourth side.

[0052] Optionally, the dimension g of the first rectangular portion 341 along the thickness direction of the pole group 2 is greater than the distance c between the final sealing portion 35 and the first side 211, thereby preventing the pole group 2 from being exposed here due to the spacing between the final sealing portion 35 and the first side 211. The first rectangular portion 341 can completely cover the part between the final sealing portion 35 and the first side 211.

[0053] Optionally, the dimension h of the second rectangular portion 361 along the thickness direction of the pole group 2 is greater than the distance d between the final sealing portion 35 and the second side 212, so as to prevent the problem of the pole group 2 being exposed here due to the spacing between the final sealing portion 35 and the second side 212. The second rectangular portion 361 can completely cover the part between the final sealing portion 35 and the second side 212.

[0054] Optionally, along the width direction of the electrode group 2, the size of the final sealing portion 35 is consistent with the size of the third end face 21. That is, the root of the final sealing portion 35 is located at one end of the third end face 21 along the width direction of the electrode group 2, and the end of the final sealing portion 35 is located at the other end of the third end face 21 along the width direction of the electrode group 2. That is, the final sealing portion 35 can completely cover the entire length direction of the third end face 21, leaving only a small gap on both sides of the final sealing portion 35, and the electrode group 2 in the small gap on both sides is covered by the two pre-sealing portions.

[0055] Optionally, the thickness of the electrode group 2 is a, and the size of the first pre-sealed portion 34 along the thickness direction of the electrode group 2 is e, 1 / 3a≤e≤0.8a. That is, the width of the first pre-sealed portion 34 cannot be less than one-third of the thickness of the electrode group 2. The thickness of the long knife battery cell is generally small. If the width of the first pre-sealed portion 34 is less than one-third of the thickness of the electrode group 2, the width of the first pre-sealed portion 34 will be too small. Not only will there be no overlapping area between the two pre-sealed portions, but the overlapping area between the first pre-sealed portion 34 and the final sealing portion 35 will also be insufficient, resulting in insufficient hot melt area, insufficient connection strength between the first pre-sealed portion 34 and the final sealing portion 35, and easy failure under the action of external force. However, if the width of the first pre-sealed portion 34 is greater than 0.8 times the thickness of the pole group 2, the overlapping area between the two pre-sealed portions is too large, and the overlapping area between the first pre-sealed portion 34 and the final sealing portion 35 is also too large. The three layers are superimposed and the area is too large, which can easily cause wrinkles, causing the inner insulating film 3 at the third end face 21 to be too thick, occupying too much space in the outer shell 1, and there is a problem of material waste.

[0056] Optionally, the size of the second pre-sealed portion 36 is f, 1 / 3a≤f≤0.8a. That is, the width of the second pre-sealed portion 36 cannot be less than one-third of the thickness of the pole group 2. The thickness of the long knife battery core is generally small. If the width of the second pre-sealed portion 36 is less than one-third of the thickness of the pole group 2, the width of the second pre-sealed portion 36 will be too small. Not only will there be no overlapping area between the two pre-sealed portions, but the overlapping area between the second pre-sealed portion 36 and the final sealing portion 35 will also be insufficient, resulting in insufficient hot melt area, insufficient connection strength between the second pre-sealed portion 36 and the final sealing portion 35, and easy failure under external force. If the width of the second pre-sealed portion 36 is greater than 0.8 times the thickness of the pole group 2, the overlapping area between the two pre-sealed portions is too large, and the overlapping area between the second pre-sealed portion 36 and the final sealing portion 35 is also too large. The three layers are superimposed and the area is too large, which can easily cause wrinkles, causing the inner insulating film 3 at the third end face 21 to be too thick, occupying too much space in the outer shell 1, and there is a problem of material waste.

[0057] Optionally, a fourth portion 37 is connected to the side of the first portion 31 facing away from the second portion 32, and a fifth portion 38 is connected to the side of the third portion 33 facing away from the second portion 32. The fourth portion 37 and the fifth portion 38 cover the same side wall of the electrode assembly 2. Optionally, in this embodiment, the fourth portion 37 and the fifth portion 38 both cover the side wall opposite the first side wall 111. Optionally, the fourth portion 37 and the fifth portion 38 both have a rectangular structure, ensuring that no exposed area of the side wall of the electrode assembly 2 is left after covering the side wall.

[0058] Optionally, both the fourth portion 37 and the fifth portion 38 are provided with positioning holes 381 to facilitate positioning during coating of the electrode group 2. The positioning holes 381 of the fourth portion 37 and the positioning holes 381 of the fifth portion 38 are staggered to avoid exposing part of the electrode group 2.

[0059] Optionally, the opening of the inner insulating film 3 is opened corresponding to the first end surface. Optionally, the inner insulating film 3 is connected to the insulating member of the first top cover 12 by heat-melting to ensure overall insulation between the electrode group 2 and the housing 1.

[0060] Optionally, the inner insulating film 3 is a whole piece that is bent and covers the electrode group 2, and a bending line is set in advance at each bending position to facilitate bending.

[0061] Optionally, the battery cell also includes a first patch 4, a second patch 5 and an outer insulating film 6, the first patch 4 is attached to the outside of the first top cover 12, the second patch 5 is attached to the outside of the second top cover 13, and the outer insulating film 6 is wrapped around the outside of the shell body 11 to ensure that the outer shell 1 of the battery cell is not short-circuited with the outside world.

[0062] To verify that the aforementioned battery cells can prevent the escalation of thermal runaway caused by short circuits, exhibiting enhanced safety performance, and that, when meeting the aforementioned optimal dimensional conditions, the inner insulating film 3 not only prevents interference with the electrode assembly 2 entering the housing, but also prevents wrinkling, provides sufficient structural strength, and prevents insulation failure, as shown in Table 1 below, this embodiment provides ten sets of example cells and eight sets of comparative example cells. After assembly, the thermal runaway process of the cells was observed. The similarities between the ten groups of examples and the eight groups of comparative examples are that the distance c between the final sealing portion 35 and the first side 211 and the distance d between the final sealing portion 35 and the second side 212 of each group of battery cells are equal, that is, the final sealing portion 35 is located in the middle of the third end face 21, the dimension g of the first rectangular portion 341 along the thickness direction of the pole group 2 is greater than the distance c between the final sealing portion 35 and the first side 211, the dimension h of the second rectangular portion 361 along the thickness direction of the pole group 2 is greater than the distance d between the final sealing portion 35 and the second side 212, and the dimension g of the first rectangular portion 341 along the thickness direction of the pole group 2 and the dimension h of the second rectangular portion 361 along the thickness direction of the pole group 2 of each group of battery cells are equal, along the width direction of the pole group 2, the size of the final sealing portion 35 is consistent with the size of the third end face 21, and the width e of the first pre-sealed portion 34 and the width f of the second pre-sealed portion 36 of each group of battery cells are also equal.

[0063] Table 1

[0064]

[0065] Specifically, Table 1 above shows some dimensional parameters of the electrode group 2 and the internal insulating film 3 of the battery cells of ten groups of examples, and their dimensional parameters all meet the above-mentioned preferred value range. For example, the width b of the final sealing portion 35 is greater than or equal to 0.4 times the thickness of the electrode group 2, and the difference between the thickness of the electrode group 2 and the width of the final sealing portion 35 is greater than or equal to 0.8 mm, that is, the spacing c and d between the two sides of the final sealing portion 35 and the two sides of the third end face 21 are respectively greater than or equal to 0.4 mm, the width e of the first pre-sealing film satisfies 1 / 3a≤e≤0.8a, and the width f of the second pre-sealing film satisfies 1 / 3a≤f≤0.8a.

[0066] After testing, it was found that after the abnormal heating and thermal runaway of the battery cells in these ten groups of examples, the thermal runaway did not cause the insulation parts to melt and short-circuit, and the thermal runaway escalation. In addition, the internal insulating film 3 not only did not cause the pole group 2 to interfere with the shell, but also rarely had wrinkles. The internal insulating film 3 also had sufficient structural strength, and the insulation would not fail.

[0067] The final seal 35 of the battery cells in Comparative Examples 1 and 2 in Table 1 above is too wide. In Comparative Example 1, the spacing c and d between the sides of the final seal 35 and the sides of the third end face 21 are only 0.1mm, while in Comparative Example 2, the spacing c and d between the sides of the final seal 35 and the sides of the third end face 21 are only 0.25mm. In other words, the final seal 35 of the battery cells in these two sets of comparative examples is too wide. When there is positioning deviation, the final seal 35 is very likely to shift to the side with the largest area of the electrode group 2, causing the thickness of the electrode group 2 to increase, causing scratches during insertion, and increasing resistance to insertion. After testing, the abnormal heating and thermal runaway of the battery cells in these two sets of comparative examples did not cause the insulation to melt and short-circuit and escalate to thermal runaway, but the defect rate caused by the displacement of the internal insulating film 3 was relatively high.

[0068] The final sealing portion 35 of the battery cells of Comparative Examples 3 and 4 in Table 1 above is too narrow. The width b of the final sealing portion 35 in Comparative Examples 3 and 4 is less than 0.4 times the thickness of the electrode group 2. The narrowness of the final sealing portion 35 will result in the exposure of the two pre-sealing portions. The insufficient heat-melting area between the two pre-sealing portions and the final sealing portion 35 will lead to insufficient structural strength and the possibility of warping of the two pre-sealing portions. After testing, the abnormal heating and thermal runaway of the battery cells in these two groups of comparative examples did not cause the insulation to heat up and short-circuit and escalate to thermal runaway. However, due to the insufficient structural strength of the inner insulating film 3, the defective ratio caused by the warping of the two pre-sealing portions was relatively high.

[0069] The first pre-sealed portion 34 and the second pre-sealed portion 36 of the battery cells of Comparative Examples 5 and 6 in Table 1 above are both too wide. The width of the first pre-sealed portion 34 and the second pre-sealed portion 36 in Comparative Examples 5 and 6 exceeds 0.8 times the thickness of the electrode group 2. Excessively wide pre-sealed portions can easily wrinkle during wrapping, resulting in low wrapping efficiency. Furthermore, the wrinkles will further increase the thickness of the inner insulating film 3 at the third end face 21, further occupying the space within the battery cell's outer shell 1 and hindering the internal layout of the battery cell. Upon testing, the abnormal heating and thermal runaway of the battery cells in these two groups of comparative examples did not cause the insulation to melt, short-circuit, or escalate to thermal runaway, but the defective ratio caused by wrinkling of the pre-sealed portions was high.

[0070] The first pre-sealed portion 34 and the second pre-sealed portion 36 of the battery cells of Comparative Examples 7 and 8 in Table 1 above are both too narrow, and the width of the first pre-sealed portion 34 and the second pre-sealed portion 36 in Comparative Examples 7 and 8 is less than one-third of the thickness of the electrode group 2. The two pre-sealed portions are too narrow, which will result in insufficient hot melting. Even after hot melting, when the electrode group 2 encounters resistance when entering the shell, the hot-melt connection area between the two pre-sealed portions and the final sealing portion 35 is also very easy to be pulled off, causing insulation failure here. After testing, the battery cells of these two groups of comparative examples did not cause the insulation to escalate to hot melt short circuit and thermal runaway after abnormal temperature rise and thermal runaway, but the defective ratio caused by the disconnection between the final sealing portion 35 and the two pre-sealed portions was relatively high.

[0071] This embodiment also provides a battery module, comprising a module housing and the above-mentioned battery cell, wherein the battery cell is disposed in the module housing. Optionally, a plurality of battery cells are provided, and the plurality of battery cells are arranged in sequence along the thickness direction of the module housing.

[0072] The battery cell of the battery module can greatly increase the thermoelectric distance by arranging the positive output terminal 121 and the negative output terminal 122 at the same end and arranging the explosion-proof valve 14 on the side wall away from this end, thereby preventing the high-temperature fluid at the explosion-proof valve 14 from affecting the insulating parts at the positive output terminal 121 and the negative output terminal 122 when the battery cell thermal runaway occurs, thereby preventing the escalation of thermal runaway caused by the melting of the insulating parts and the short circuit of the battery cell, so that the battery cell has higher safety performance.

[0073] The battery cell of the battery module has an internal insulating film 3 with a suitable structure. The size of the internal insulating film 3 is better. It not only does not interfere with the insertion of the electrode group 2 into the shell, but also prevents wrinkles and has sufficient structural strength to ensure that there will be no insulation failure.

[0074] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A battery cell, characterized in that: include: A housing (1), the housing (1) having a first end face and a second end face arranged opposite to each other along a first direction, the first end face being provided with a positive output terminal (121) and a negative output terminal (122), and an explosion-proof valve (14) being provided on a first side wall (111) of the housing (1) away from the first end face; A pole group (2), the pole group (2) being arranged in the housing (1), the pole group (2) having a third end surface (21), the third end surface (21) being arranged corresponding to the second end surface; An inner insulating film (3), the inner insulating film (3) is bent and wrapped around the pole group (2), and is sandwiched between the pole group (2) and the outer shell (1), the inner insulating film (3) comprises a first part (31), a second part (32) and a third part (33) connected in sequence, the first part (31) is connected to a first pre-sealing part (34) along the side of the first direction, the second part (32) is connected to a final sealing part (35) along the side of the first direction, the third part (33) is connected to a second pre-sealing part (36) along the side of the first direction, the first pre-sealing part (34), the second pre-sealing part (36) and the final sealing part (35) are all wrapped around the third end face (21), and the final sealing part (35) is located outside the first pre-sealing part (34) and the second pre-sealing part (36).

2. The battery cell according to claim 1, characterized in that The first portion (31) and the third portion (33) are arranged opposite to each other along the thickness direction of the pole group (2), the thickness of the pole group (2) is a, and along the thickness direction of the pole group (2), the size of the final sealing portion (35) is b, satisfying: b≥0.4a.

3. The battery cell according to claim 1, characterized in that The first portion (31) and the third portion (33) are arranged opposite to each other along the thickness direction of the pole group (2); the third end surface (21) has a first side edge (211) and a second side edge (212) arranged opposite to each other along the thickness direction of the pole group (2); the final sealing portion (35) is spaced apart from both the first side edge (211) and the second side edge (212); the distance between the final sealing portion (35) and the first side edge (211) is c, and the distance between the final sealing portion (35) and the second side edge (212) is d, satisfying the following conditions: 0.4 mm ≤ c ≤ 15 mm, 0.4 mm ≤ d ≤ 15 mm.

4. The battery cell according to claim 3, characterized in that The third end surface (21) further has a third side and a fourth side that are arranged opposite to each other, and the inner insulating film (3) satisfies: The first pre-sealing portion (34) comprises a first rectangular portion (341), one side of the first rectangular portion (341) is located on the first side (211), and the other two sides of the first rectangular portion (341) are respectively located on the third side and the fourth side; And / or, the second pre-sealed portion (36) includes a second rectangular portion (361), one side of the second rectangular portion (361) is located on the second side (212), and the other two sides of the second rectangular portion (361) are respectively located on the third side and the fourth side.

5. The battery cell according to claim 4, characterized in that: A dimension g of the first rectangular portion (341) along the thickness direction of the pole group (2) is greater than a distance c between the final sealing portion (35) and the first side (211); And / or, a dimension h of the second rectangular portion (361) along the thickness direction of the pole group (2) is greater than a distance d between the final sealing portion (35) and the second side (212).

6. The battery cell according to any one of claims 1 to 5, characterized in that: The first direction is the length direction of the pole group (2), the first portion (31) and the third portion (33) are arranged relative to each other along the thickness direction of the pole group (2), and along the width direction of the pole group (2), the size of the final sealing portion (35) is consistent with the size of the third end face (21).

7. The battery cell according to any one of claims 1 to 5, characterized in that: The first portion (31) and the third portion (33) are arranged opposite to each other along the thickness direction of the pole group (2), and the thickness of the pole group (2) is a, satisfying: Along the thickness direction of the electrode group (2), the size of the first pre-sealed portion (34) is e, 1 / 3a≤e≤0.8a; And / or, along the thickness direction of the electrode group (2), the size of the second pre-sealed portion (36) is f, 1 / 3a≤f≤0.8a.

8. The battery cell according to any one of claims 1 to 5, characterized in that: The side of the first portion (31) facing away from the second portion (32) is connected to the fourth portion (37), the side of the third portion (33) facing away from the second portion (32) is connected to the fifth portion (38), and the fourth portion (37) and the fifth portion (38) cover the same side wall of the pole group (2).

9. The battery cell according to any one of claims 1 to 5, characterized in that: The opening of the inner insulating film (3) is opened corresponding to the first end surface.

10. A battery module, characterized in that: The invention comprises a module shell and the battery core according to any one of claims 1 to 9, wherein the battery core is arranged in the module shell.

Images