Battery cell and battery pack

Abstract

The application relates to the technical field of batteries and discloses a battery cell and a battery pack. The battery cell comprises a shell, an open end of the shell, a pole group arranged in the shell, the pole group comprising a positive pole sheet, a diaphragm and a negative pole sheet arranged in layers, the diaphragm extending out of the upper side walls of the positive pole sheet and the negative pole sheet, a battery cell cover plate assembly comprising a cover plate and a lower plastic, the cover plate being arranged on the open end, the lower plastic being arranged on the lower surface of the cover plate and in the shell, the lower surface of the lower plastic being provided with a separation part and a pair of limiting parts, the pair of limiting parts being respectively arranged at opposite ends of the lower surface of the lower plastic, the separation part being arranged between the pair of limiting parts, the end area of the separation part away from the cover plate being smaller than the end area of the limiting part away from the cover plate, the length of the separation part being smaller than the length of the limiting part, and the separation part and the limiting part both abutting against the part of the diaphragm extending out of the positive pole sheet and the negative pole sheet. The compression amount of the separation part on the diaphragm is reduced, and the possibility of damage of the separation part to the pole group is reduced.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a battery cell and battery pack. Background Technology

[0002] To prevent contact between the positive and negative tabs in the battery cell, an insulating separator is usually installed on the lower surface of the plastic under the battery cell, and this insulating separator is placed between the positive and negative tabs.

[0003] To meet different cell design requirements, some designs currently reduce the spacing between the positive and negative tabs. Based on this, to accommodate these designs, the size of the insulating spacer needs to be reduced to avoid interference between the insulating spacer and the positive and negative tabs. However, when the size of the insulating spacer is reduced, the contact area between the insulating spacer and the upper surface of the electrode assembly decreases accordingly. Therefore, when the cell is under manufacturing or vibration conditions, the insulating spacer is prone to damaging the positive and / or negative electrode plates in the electrode assembly, potentially leading to a short circuit in the cell. Summary of the Invention

[0004] This invention provides a battery cell and battery pack to solve the problem that small-sized insulating separators can easily cause damage to the positive and / or negative electrode plates of the electrode assembly.

[0005] In a first aspect, the present invention provides a battery cell, comprising:

[0006] The housing has an opening at one end along the Z-direction;

[0007] An electrode assembly is disposed within the housing through the opening. The electrode assembly includes a positive electrode, a separator, and a negative electrode stacked along the Y direction. Along the Z direction, a portion of the separator extends beyond the upper sidewalls of the positive and negative electrode.

[0008] A cell cover assembly includes a cover plate and a lower plastic layer, the cover plate covering the opening; along the Z direction, the lower plastic layer is located on the lower surface of the cover plate and within the housing, the lower surface of the lower plastic layer has a partition portion and a pair of limiting portions, along the X direction, the pair of limiting portions are respectively located at opposite ends of the lower surface of the lower plastic layer, the partition portion is located between the pair of limiting portions; along the Z direction, the end area of ​​the partition portion away from the cover plate is smaller than the end area of ​​the limiting portion away from the cover plate, the length of the partition portion is smaller than the length of the limiting portion, and both the partition portion and the limiting portion abut against portions of the separator extending from the positive electrode and the negative electrode.

[0009] Beneficial Effects: This invention utilizes a limiting portion with a larger end area to abut against the portions of the separator extending from the positive and negative electrode plates. This achieves reliable limiting of the electrode assembly while dispersing pressure through a larger contact area, preventing the limiting portion from damaging the positive and / or negative electrode plates. Simultaneously, by placing a pair of limiting portions at opposite ends in the X direction on the lower surface of the lower plastic, symmetrical limiting of the electrode assembly can be formed from both sides, improving the positional stability of the electrode assembly within the housing and reducing displacement deviation of the electrode assembly under cell manufacturing processes and vibration conditions. Furthermore, this invention abuts the separator portion against the portions of the separator extending from the positive and negative electrode plates, and makes the length of the separator portion less than the length of the limiting portion, thus preventing the separator portion from damaging the positive and / or negative electrode plates of the electrode assembly. Specifically, because the length of the separator portion is less than the length of the limiting portion, the compression of the separator portion on the separator can be reduced, increasing the distance between the separator portion and the positive and negative electrode plates, thereby reducing the possibility of damage to the positive and negative electrode plates by the separator portion during cell manufacturing processes or vibration conditions. In addition, when the partition comes into contact with the upper sidewall of the diaphragm, the partition can also play an auxiliary limiting role, further constraining the displacement of the electrode assembly along the Z direction and enhancing the overall structural stability of the electrode assembly.

[0010] In one optional embodiment, along the Z direction, the length difference between the limiting portion and the separating portion is h, and the end area of ​​the separating portion away from the cover plate is S, and the relationship between h and S satisfies one of the following characteristics:

[0011] (a) 30mm 2 ≤S≤300mm 2 , 0.5mm≤h≤1mm;

[0012] (ii) If S≥300mm 2 , 0mm < h < 0.5mm.

[0013] Beneficial effects: When the end area S of the separator is in the range of 30mm²≤S≤300mm², a length difference of 0.5mm≤h≤1mm can ensure that the separator has sufficient structural strength to achieve reliable insulation between the positive and negative tabs, adapting to small-pitch tab designs. It can also rely on the large contact area of ​​the limiting part to disperse pressure, while avoiding damage to the electrode assembly by the separator. When the end area S of the separator is greater than or equal to 300mm², controlling the length difference h to 0mm<h<0.5mm can shorten the length difference between the two under the premise that the separator itself has strong structural stability and a large contact area. This allows the separator to assist the limiting part in constraining the displacement of the electrode assembly along the Z direction, further improving the positional stability of the electrode assembly, while avoiding the risk of excessive interference between the separator and the electrode assembly when the cell is under process and vibration conditions.

[0014] In one optional embodiment, along the Z direction, the length of the limiting portion is a, and the value of a ranges from 2mm ≤ a ≤ 6mm; and / or, on the XY plane, the ratio of the sum of the orthographic projection areas of a pair of limiting portions to the orthographic projection area of ​​the outer contour of the lower plastic is 20% to 50%.

[0015] Beneficial effects: This invention controls the length 'a' of the limiting part within the range of 2mm to 6mm, ensuring sufficient heat-fusion area between the limiting part and the insulating film on the outer periphery of the electrode assembly, thus ensuring a strong heat-fusion connection and guaranteeing the protective effect of the insulating film on the electrode assembly. Furthermore, in the XY plane, the ratio of the sum of the projected areas of a pair of limiting parts to the projected area of ​​the lower plastic outer contour is limited to 20% to 50%. This ensures that the limiting part has sufficient structural volume and contact area, stably dispersing pressure to avoid damaging the electrode assembly, while also enhancing the stability of the symmetrical limiting on both sides. In addition, it allows for reasonable space to be reserved for the partition and other assembly structures on the lower plastic, balancing functional integrity and structural layout rationality.

[0016] In one optional embodiment, the electrode assembly has a positive electrode tab and a negative electrode tab spaced apart along the X direction at one end near the opening. The positive electrode tab is located between the separator and one of the limiting parts, and the negative electrode tab is located between the separator and the other limiting part. Along the X direction, at least a portion of the positive electrode tab and the negative electrode tab are projected toward the separator into the projection range of the separator.

[0017] Beneficial effects: By placing the positive and negative tabs between the separator and the limiting parts on both sides, and ensuring that the orthogonal projections of the positive and negative tabs toward the separator fall within the range of the separator along the X direction, the separator can form an insulating isolation between the positive and negative tabs, blocking the contact path between them. Simultaneously, this arrangement achieves partitioning of the positive and negative tabs with the separator and limiting parts, adapting to the design requirements of small spacing between the positive and negative tabs, effectively avoiding structural interference between the tabs and the separator and limiting parts. Furthermore, this arrangement is compatible with the symmetrical limiting structure of the limiting parts, further optimizing the structural matching degree between the lower plastic and the tab area, improving the rationality of the internal structural layout of the battery cell, and thus enhancing the overall safety of the battery cell.

[0018] In one optional embodiment, the upper surface of the cover plate is provided with a first protrusion that protrudes upward along the Z direction, and the first protrusion forms a first groove on one side of the lower surface of the cover plate, with the positive electrode tab and the negative electrode tab partially extending into the first groove.

[0019] Beneficial effects: The present invention provides a first convex bump that protrudes upward along the Z direction on the upper surface of the cover plate, and forms a corresponding first groove on the lower surface of the cover plate, so that the positive and negative tabs extend into the first groove. This arrangement can, on the one hand, provide dedicated space for the tabs through the first groove, avoid the tabs from occupying too much internal space of the shell, and thus allow more space to be reserved in the shell to accommodate the electrode assembly, thereby improving the energy density of the cell; on the other hand, the first convex bump can enhance the compressive and deformation resistance of the cover plate at this location, thereby preventing the cover plate from being damaged by the tabs due to deformation caused by external forces.

[0020] In one optional embodiment, the upper surface of the lower plastic is provided with a second protrusion that protrudes upward along the Z direction, at least a portion of the second protrusion extending into the first groove; the second protrusion forms a second groove on one side of the lower surface of the lower plastic, at least a portion of the separator is located in the second groove, and a portion of the positive electrode tab and the negative electrode tab extend into the second groove.

[0021] Beneficial effects: First, the fitting structure of the second protrusion and the first groove enables precise positioning and assembly of the lower plastic and the cover plate, improving the overall structural fit and assembly stability of the cell cover plate assembly and reducing displacement deviation between components; Second, the second groove provides an integrated accommodating and limiting space for the separator and positive and negative tabs, which can constrain the position of the separator and ensure its effectiveness in insulating and isolating the positive and negative tabs; Third, the second protrusion can structurally reinforce the area of ​​the lower plastic corresponding to the tab and the separator, enhancing the lower plastic's resistance to deformation at that location and preventing damage to the tab or separator due to external pressure deformation.

[0022] In one optional embodiment, the positive electrode tab and the negative electrode tab are spaced apart from the partition and the groove wall of the second groove.

[0023] Beneficial effects: The present invention arranges the positive electrode tab, negative electrode tab, separator, and second groove wall at intervals. On the one hand, it can effectively avoid hard contact between the electrode tab and the separator and groove wall, ensuring the structural integrity of the electrode tab. On the other hand, the reserved interval space can accommodate the thermal expansion and contraction deformation of the battery cell during use, avoiding structural failure caused by mutual compression of the components due to deformation.

[0024] In one optional embodiment, along the X direction, a plurality of reinforcing ribs are provided on opposite sides of the partition, and the plurality of reinforcing ribs located on opposite sides of the partition in the X direction are arranged opposite each other in pairs.

[0025] Beneficial Effects: Along the X-direction, this invention provides multiple reinforcing ribs on opposite sides of the separator, with the ribs arranged in pairs facing each other. On one hand, this enhances the overall structural strength and deformation resistance of the separator, preventing bending or displacement during cell manufacturing, assembly, or vibration conditions, thus ensuring the structural stability and effectiveness of its insulation isolation of the positive and negative tabs. On the other hand, the opposing reinforcing ribs form a symmetrical structural support, ensuring uniform stress on the separator and further improving its structural reliability, preventing structural damage caused by excessive local stress. Furthermore, the reinforcing ribs do not require altering the basic dimensions of the separator to accommodate the small spacing between the positive and negative tabs. While strengthening structural performance, it still meets the design requirements for small tab spacing, balancing structural protection and spatial adaptability of the separator, further ensuring the insulation isolation effect and overall structural stability of the cell tab area.

[0026] In one alternative embodiment, the cross-sectional area of ​​the reinforcing rib gradually increases along the direction from the opening of the second groove to the bottom of the second groove.

[0027] Beneficial effects: By setting the cross-sectional area of ​​the reinforcing rib to gradually increase along the direction from the opening to the bottom of the second groove, the structural strength of the reinforcing rib can be increased synchronously with the depth of the second groove, matching the stress bearing requirements at different locations and effectively avoiding structural failure problems such as cracking and deformation caused by stress concentration. At the same time, this gradual cross-sectional area design can reasonably allocate the amount of reinforcing rib material while ensuring the structural support and reinforcement effect, reducing unnecessary material redundancy, and taking into account the structural stability and lightweight design requirements of the product.

[0028] Secondly, the present invention also provides a battery pack including the aforementioned battery cell.

[0029] Beneficial effects: The battery pack of the present invention includes the battery cell as described above and has all the beneficial technical effects of the battery cell, which will not be repeated here. Attached Figure Description

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in 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 the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of a battery cell according to an embodiment of the present invention;

[0032] Figure 2 for Figure 1 The exploded view of the battery cell shown.

[0033] Figure 3 for Figure 1 A cross-sectional view of the battery cell shown.

[0034] Figure 4 for Figure 3 A magnified view of part M in the diagram;

[0035] Figure 5 for Figure 4 A magnified view of a portion of P;

[0036] Figure 6 for Figure 1 The image shows an exploded view of the battery cell from another perspective;

[0037] Figure 7 for Figure 6 A magnified view of N in the diagram.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1. Housing; 2. Electrode assembly; 201. Positive electrode tab; 202. Negative electrode tab; 3. Cell cover assembly; 301. Cover plate; 3011. First protrusion; 302. Lower plastic; 3021. Separator; 3022. Limiting part; 3023. Second protrusion; 3024. Second groove; 4. Reinforcing rib. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] The following is combined Figures 1 to 7 The following describes embodiments of the present invention. For ease of description thereafter, as... Figure 1 As shown, a spatial rectangular coordinate system is established: the height direction of the battery cell extends along the Z direction; the length direction of the battery cell extends along the X direction; and the width direction (or thickness direction) of the battery cell extends along the Y direction.

[0042] According to embodiments of the present invention, in one aspect, such as Figure 1 , Figure 2 as well as Figure 6 As shown, a battery cell is provided, including: a housing 1, an electrode group 2, and a battery cell cover assembly 3.

[0043] Specifically, along the Z-direction, the end of the housing 1 has an opening; the electrode assembly 2 is disposed inside the housing 1 through the opening, and the electrode assembly 2 includes a positive electrode plate, a separator, and a negative electrode plate stacked along the Y-direction. Along the Z-direction, the separator partially extends out of the upper sidewalls of the positive and negative electrode plates; the cell cover assembly 3 includes a cover plate 301 and a lower plastic 302, the cover plate 301 covering the opening; along the Z-direction, the lower plastic 302 is located on the lower surface of the cover plate 301 and inside the housing 1, and the lower surface of the lower plastic 302 is provided with a partition 3021 and a... Regarding the limiting portion 3022, along the X direction, a pair of limiting portions 3022 are located at opposite ends of the lower surface of the lower plastic 302, and the separating portion 3021 is located between the pair of limiting portions 3022; along the Z direction, the end area of ​​the separating portion 3021 away from the cover plate 301 is smaller than the end area of ​​the limiting portion 3022 away from the cover plate 301, and the length of the separating portion 3021 is smaller than the length of the limiting portion 3022. Both the separating portion 3021 and the limiting portion 3022 abut against the portions of the diaphragm that extend out to form the positive and negative electrode plates.

[0044] This embodiment utilizes a limiting portion 3022 with a larger end area to abut against the portions of the separator extending from the positive and negative electrode plates. This achieves reliable positioning of the electrode assembly 2 while dispersing pressure through a larger contact area, preventing the limiting portion 3022 from damaging the positive and / or negative electrode plates. Simultaneously, by placing a pair of limiting portions 3022 at opposite ends of the lower surface of the lower plastic 302 in the X direction, symmetrical positioning of the electrode assembly 2 from both sides is achieved, improving the positional stability of the electrode assembly 2 within the housing 1 and reducing displacement deviation of the electrode assembly 2 under cell manufacturing processes and vibration conditions. Furthermore, this embodiment abuts the separating portion 3021 against the portions of the separator extending from the positive and negative electrode plates, and makes the length of the separating portion 3021 less than the length of the limiting portion 3022, thus preventing the separating portion 3021 from damaging the positive and / or negative electrode plates of the electrode assembly 2. Specifically, since the length of the separator 3021 is less than the length of the limiting portion 3022, the compression of the separator 3021 on the diaphragm can be reduced, increasing the distance between the separator 3021 and the positive and negative electrode plates. This reduces the possibility of damage to the positive and negative electrode plates caused by the separator 3021 when the cell is under process or vibration conditions. Furthermore, when the separator 3021 abuts against the diaphragm, it also plays an auxiliary limiting role, further constraining the displacement of the electrode assembly 2 along the Z direction and enhancing the overall structural stability of the electrode assembly 2.

[0045] Specifically, in this embodiment, along the Y direction, the orthogonal projections of the positive and negative electrode plates toward the separator fall within the range of the separator; and separators are provided on both opposite sides of the positive and negative electrode plates in the Y direction. This ensures that short circuits caused by direct contact between the positive and negative electrode plates are prevented.

[0046] Specifically, in this embodiment, the separator 3021 and the limiting part 3022 can be integrally molded with the lower plastic 302, or they can be independent components connected separately to the lower plastic 302, as long as the electrode group 2 and the cover plate 301 can be insulated and isolated. Preferably, the separator 3021 and the limiting part 3022 are integrally injection molded with the lower plastic 302. Specifically, the integral molding process can simplify the production process, reduce the assembly steps of parts, reduce the labor and material costs of production, processing and assembly, improve production efficiency, and the integrally molded structure has no splicing gaps, which can further optimize the internal space utilization of the battery cell, avoid gaps occupying extra internal space, and take into account both the compactness of the battery cell structure and the insulation protection effect.

[0047] It should be noted that in conventional designs, the size of the separator is larger than the size of the negative electrode, and the size of the negative electrode is larger than the size of the positive electrode. Therefore, the limiting part 3022 will preferentially abut against the upper sidewall of the negative electrode and achieve Z-axis limiting of the electrode group to prevent the electrode group from moving inside the cell.

[0048] Furthermore, such as Figures 3 to 5 As shown, along the Z direction, the length difference between the limiting part 3022 and the separating part 3021 is h, and the end area of ​​the separating part 3021 away from the cover plate 301 is S. The relationship between h and S satisfies one of the following characteristics:

[0049] (a) 30mm 2 ≤S≤300mm 2 , 0.5mm≤h≤1mm;

[0050] (ii) If S≥300mm 2 , 0mm < h < 0.5mm.

[0051] It is understandable that when the end area S of the separator 3021 is in the range of 30mm²≤S≤300mm², a length difference of 0.5mm≤h≤1mm can ensure that the separator 3021 has sufficient structural strength to achieve reliable insulation between the positive electrode tab 201 and the negative electrode tab 202, adapting to the small-pitch electrode tab design. It can also rely on the large contact area of ​​the limiting part 3022 to disperse pressure, while avoiding damage to the electrode group 2 by the separator 3021. When the end area S of the separator 3021 is greater than or equal to 300mm², the length difference h is controlled within the range of 0mm<h<0.5mm. Under the premise that the separator 3021 itself has strong structural stability and a large contact area, the length difference between the two can be shortened, so that the separator 3021 can assist the limiting part 3022 in constraining the displacement of the electrode group 2 in the Z direction, further improving the positional stability of the electrode group 2, while avoiding the risk of excessive interference between the separator 3021 and the electrode group 2 when the cell is under process and vibration conditions.

[0052] In one embodiment, such as Figure 3 As shown, along the Z direction, the length of the limiting part 3022 is 'a', and the value of 'a' ranges from 2mm to 6mm; and / or, on the XY plane, the ratio of the sum of the projected areas of a pair of limiting parts 3022 to the projected area of ​​the outer contour of the lower plastic 302 is 20% to 50%. In this embodiment, controlling the length 'a' of the limiting part 3022 within the range of 2mm to 6mm ensures sufficient heat-fusion area between the limiting part 3022 and the insulating film on the outer periphery of the electrode assembly 2, ensuring a strong heat-fusion connection between the two, and thus guaranteeing the protective effect of the insulating film on the electrode assembly 2. Furthermore, limiting the ratio of the sum of the projected areas of a pair of limiting parts 3022 to the projected area of ​​the outer contour of the lower plastic 302 on the XY plane to 20% to 50% ensures that the limiting part 3022 has sufficient structural volume and contact area, stably dispersing pressure to avoid damaging the electrode assembly 2, while also enhancing the stability of the symmetrical limiting on both sides. In addition, it can reserve reasonable space for the partition 3021 and other assembly structures on the lower plastic 302, taking into account both functional integrity and structural layout rationality.

[0053] It can be understood that the value of 'a' can be 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, or any value between two of these. The ratio of the sum of the projected areas of the pair of limiting parts 3022 to the projected area of ​​the outer contour of the lower plastic 302 can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any value between two of these.

[0054] In one embodiment, such as Figures 2 to 5As shown, the pole group 2 has a positive electrode tab 201 and a negative electrode tab 202 spaced apart along the X direction at one end near the opening. The positive electrode tab 201 is located between the partition 3021 and one of the limiting parts 3022, and the negative electrode tab 202 is located between the partition 3021 and the other limiting part 3022. Along the X direction, at least part of the orthographic projection of the positive electrode tab 201 and the negative electrode tab 202 toward the partition 3021 falls within the orthographic projection range of the partition 3021. In this embodiment, the positive tab 201 and negative tab 202 are respectively disposed between the separator 3021 and the limiting portions 3022 on both sides, and the orthogonal projections of the positive and negative tabs toward the separator 3021 fall within the range of the separator 3021 along the X direction. This allows the separator 3021 to form an insulating isolation between the positive tab 201 and the negative tab 202, blocking the contact path between the positive tab 201 and the negative tab 202. At the same time, this arrangement realizes the partitioning of the positive and negative tabs with the separator 3021 and the limiting portions 3022, which can adapt to the design requirements of small spacing between the positive and negative tabs, effectively avoiding structural interference between the tabs and the separator 3021 and the limiting portions 3022. Moreover, this arrangement is compatible with the symmetrical limiting structure of the limiting portion 3022, further optimizing the structural matching degree between the lower plastic 302 and the tab area, improving the rationality of the internal structural layout of the battery cell, and thus enhancing the overall safety of the battery cell.

[0055] Furthermore, such as Figures 1 to 5 As shown, the upper surface of the cover plate 301 is provided with a first protrusion 3011 that protrudes upward along the Z direction. The first protrusion 3011 forms a first groove on one side of the lower surface of the cover plate 301, and the positive electrode tab 201 and the negative electrode tab 202 partially extend into the first groove. It can be understood that in this embodiment, the first protrusion 3011 that protrudes upward along the Z direction is provided on the upper surface of the cover plate 301, and a corresponding first groove is formed on the lower surface of the cover plate 301, and the positive electrode tab 201 and the negative electrode tab 202 partially extend into the first groove. With this arrangement, on the one hand, the first groove can provide dedicated space for the tabs, avoiding the tabs from excessively occupying the internal space of the housing 1, thereby allowing more space to be reserved in the housing 1 to accommodate the electrode group 2, which can improve the energy density of the cell; on the other hand, the first protrusion 3011 can enhance the compressive and deformation resistance of the cover plate 301 at this position, thereby preventing the cover plate 301 from being damaged by the tabs due to deformation caused by external forces.

[0056] It is understood that in this embodiment, the first protrusion 3011 and the cover plate 301 are integrally stamped.

[0057] Furthermore, such as Figures 1 to 5As shown, the upper surface of the lower plastic 302 is provided with a second protrusion 3023 that protrudes upward along the Z direction, and at least a portion of the second protrusion 3023 extends into the first groove; the second protrusion 3023 forms a second groove 3024 on one side of the lower surface of the lower plastic 302, at least a portion of the partition portion 3021 is located in the second groove 3024, and the positive electrode tab 201 and the negative electrode tab 202 partially extend into the second groove 3024. It is understandable that the fitting structure of the second protrusion 3023 and the first groove can achieve precise positioning and assembly of the lower plastic 302 and the cover plate 301, improve the overall structural fit and assembly stability of the cell cover plate assembly 3, and reduce displacement deviation between components; secondly, the second groove 3024 provides an integrated accommodating and limiting space for the separator 3021 and the positive and negative electrodes, which can constrain the position of the separator 3021 and ensure its effectiveness in insulating and isolating the positive and negative electrodes; furthermore, the second protrusion 3023 can form a structural reinforcement in the area of ​​the lower plastic 302 corresponding to the electrodes and the separator 3021, enhance the deformation resistance of the lower plastic 302 at this position, and prevent it from being deformed by external force and damaging the electrodes or the separator 3021.

[0058] Furthermore, such as Figure 3 and Figure 4 As shown, the positive electrode tab 201 and the negative electrode tab 202 are spaced apart from the partition portion 3021 and the groove wall of the second groove 3024. It can be understood that this embodiment uses a spaced-apart arrangement between the positive electrode tab 201, the negative electrode tab 202 and the partition portion 3021 and the groove wall of the second groove 3024. This effectively avoids hard contact between the electrode tabs and the partition portion 3021 and the groove wall, ensuring the structural integrity of the electrode tabs. Furthermore, the reserved space can accommodate thermal expansion and contraction deformation during the use of the battery cell, preventing structural failure caused by mutual compression of components due to deformation.

[0059] Furthermore, such as Figure 4 and Figure 6As shown, along the X direction, multiple reinforcing ribs 4 are provided on opposite sides of the partition 3021, and the multiple reinforcing ribs 4 on opposite sides of the partition 3021 in the X direction are arranged opposite each other in pairs. It can be understood that, along the X direction, this embodiment provides multiple reinforcing ribs 4 on opposite sides of the partition 3021, and arranges the reinforcing ribs 4 on both sides opposite each other. On the one hand, this can enhance the overall structural strength and deformation resistance of the partition 3021, prevent the partition 3021 from bending or shifting under cell manufacturing, assembly or vibration conditions, and ensure the structural stability and effectiveness of its insulation isolation of the positive and negative electrodes; on the other hand, the oppositely arranged reinforcing ribs 4 form a symmetrical structural support, so that the partition 3021 is subjected to uniform force, further improving its structural reliability and preventing structural damage caused by excessive local force. In addition, the setting of the reinforcing rib 4 does not require changing the basic dimensions of the separator 3021 to adapt to the small spacing of the positive and negative tabs. While strengthening the structural performance, it can still adapt to the design requirements of the small spacing of the tabs, taking into account both the structural protection and spatial adaptability of the separator 3021, and further ensuring the insulation isolation effect and overall structural stability of the cell tab area.

[0060] Furthermore, such as Figure 7 As shown, the cross-sectional area of ​​the reinforcing rib 4 gradually increases along the direction from the opening to the bottom of the second groove 3024. It can be understood that by setting the cross-sectional area of ​​the reinforcing rib 4 to gradually increase along the direction from the opening to the bottom of the second groove 3024, the structural strength of the reinforcing rib 4 can be synchronously improved along the depth direction of the second groove 3024, matching the load-bearing requirements at different locations and effectively avoiding structural failure problems such as cracking and deformation caused by stress concentration. At the same time, this gradually increasing cross-sectional area design can rationally allocate the material usage of the reinforcing rib 4 while ensuring structural support and reinforcement effects, reducing unnecessary material redundancy and balancing the structural stability and lightweight design requirements of the product.

[0061] The technical effects of the present invention will be described below with reference to some embodiments and comparative examples.

[0062] Table 1

[0063]

[0064] According to an embodiment of the present invention, another aspect provides a battery pack including the aforementioned battery cells.

[0065] It is understood that the battery pack of the present invention includes the above-mentioned battery cell and has all the beneficial technical effects of the battery cell, which will not be repeated here.

[0066] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that, include: The housing has an opening at one end along the Z-direction; An electrode assembly is disposed within the housing through the opening. The electrode assembly includes a positive electrode, a separator, and a negative electrode stacked along the Y direction. Along the Z direction, a portion of the separator extends beyond the upper sidewalls of the positive and negative electrode. A cell cover assembly includes a cover plate and a lower plastic layer, wherein the cover plate covers the opening; Along the Z direction, the lower plastic is located on the lower surface of the cover plate and inside the housing. The lower surface of the lower plastic is provided with a partition and a pair of limiting parts. Along the X direction, the pair of limiting parts are respectively located at opposite ends of the lower surface of the lower plastic, and the partition is located between the pair of limiting parts. Along the Z direction, the end area of ​​the partition portion away from the cover plate is smaller than the end area of ​​the limiting portion away from the cover plate, the length of the partition portion is smaller than the length of the limiting portion, and both the partition portion and the limiting portion abut against the portions of the diaphragm that extend out of the positive electrode and the negative electrode.

2. The battery cell according to claim 1, characterized in that, Along the Z direction, the length difference between the limiting part and the separating part is h, and the end area of ​​the separating part away from the cover plate is S. The relationship between h and S satisfies one of the following characteristics: (a) 30mm 2 ≤S≤300mm 2 , 0.5mm≤h≤1mm; (ii) If S≥300mm 2 , 0mm < h < 0.5mm.

3. The battery cell according to claim 1, characterized in that, Along the Z direction, the length of the limiting part is a, and the value of a ranges from 2mm ≤ a ≤ 6mm; and / or, on the XY plane, the ratio of the sum of the orthographic projection areas of a pair of limiting parts to the orthographic projection area of ​​the outer contour of the lower plastic is 20% to 50%.

4. The battery cell according to claim 1, characterized in that, The electrode assembly has a positive electrode tab and a negative electrode tab spaced apart along the X direction at one end near the opening. The positive electrode tab is located between the separator and one of the limiting parts, and the negative electrode tab is located between the separator and the other limiting part. Along the X direction, at least a portion of the positive electrode tab and the negative electrode tab are projected toward the separator into the projection range of the separator.

5. The battery cell according to claim 4, characterized in that, The upper surface of the cover plate is provided with a first protrusion that protrudes upward along the Z direction. The first protrusion forms a first groove on one side of the lower surface of the cover plate. The positive electrode tab and the negative electrode tab partially extend into the first groove.

6. The battery cell according to claim 5, characterized in that, The upper surface of the lower plastic is provided with a second protrusion that protrudes upward along the Z direction, and at least a portion of the second protrusion extends into the first groove; the second protrusion forms a second groove on one side of the lower surface of the lower plastic, at least a portion of the separator is located in the second groove, and a portion of the positive electrode tab and the negative electrode tab extend into the second groove.

7. The battery cell according to claim 6, characterized in that, The positive electrode tab and the negative electrode tab are spaced apart from the partition and the groove wall of the second groove.

8. The battery cell according to claim 6, characterized in that, Along the X direction, multiple reinforcing ribs are provided on opposite sides of the partition, and the multiple reinforcing ribs located on opposite sides of the partition in the X direction are arranged opposite each other in pairs.

9. The battery cell according to claim 8, characterized in that, Along the direction from the opening of the second groove to the bottom of the second groove, the cross-sectional area of ​​the reinforcing rib gradually increases.

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

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