Battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell and a battery pack. The battery cell comprises a pole group; the packaging film comprises a main body part and an edge folding structure, the main body part is provided with a closed accommodating space, the accommodating space is suitable for accommodating the pole group, and the total thickness of the main body part and the pole group in the Z direction is T; the edge folding structure is connected to at least one side of the main body part in the X direction, the edge folding structure comprises a supporting unit and a wrapping edge, the supporting unit comprises a plurality of folding sections stacked in the Z direction, the wrapping edge is located on the side, away from the main body part, of the supporting unit in the X direction, the size of the supporting unit in the Z direction is W, and W and T meet the relational expression that W / T is larger than or equal to 0.5 and smaller than 1. The supporting unit is elastically supported between the main body part and the covered edge, external impact force is prevented from directly acting on the main body part, so that the buffering effect on the external impact force is achieved, and the balance between the impact resistance effect and the space utilization rate is achieved by limiting W / T to be within the range of 0.5-1.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a battery cell and a battery pack. Background Art

[0002] The battery cell has advantages such as high specific energy, small volume, and light weight, and has a large application market. The battery cell mainly consists of a tab, an electrode assembly, and a packaging film. The packaging film encapsulates the electrode assembly and the tab, and the four peripheral edges of the packaging film are sealed by hot pressing to seal and protect the electrode assembly. However, during the handling of the battery cell or during the operation of the battery cell applied in a vehicle, the battery cell is easily subjected to external impacts or squeezes. The existing packaging film usually only simply wraps the electrode assembly. Although it can meet the basic packaging requirements, when the battery cell is subjected to external impacts or squeezes, the protection effect of the packaging film on the electrode assembly is insufficient, which is likely to cause damage to the internal electrode assembly, resulting in situations such as the battery cell being deformed under pressure and short circuit inside the battery cell, leading to a decline or failure of the battery cell performance, and having a great danger. Summary of the Invention

[0003] In view of this, the present invention provides a battery cell and a battery pack to solve the problem that the protection effect of the packaging film on the electrode assembly is insufficient and the electrode assembly is easily damaged when subjected to external impacts.

[0004] In a first aspect, the present invention provides a battery cell, including: an electrode assembly; a packaging film, including a main body portion and a folded edge structure. The main body portion has a closed accommodation space suitable for accommodating the electrode assembly, and the total thickness of the main body portion and the electrode assembly in the Z direction is T. The folded edge structure is connected to at least one side of the main body portion along the X direction. The folded edge structure includes a support unit and a wrapping edge. The support unit includes a plurality of folded segments stacked along the Z direction, and the wrapping edge is located on the side of the support unit away from the main body portion along the X direction. The size of the support unit in the Z direction is W, where the relationship between W and T satisfies: 0.5 ≤ W / T < 1.

[0005] Beneficial effects: By providing that the encapsulation film includes a main body portion for accommodating the electrode group and a hemming structure connected to at least one side of the main body portion, and the hemming structure includes a support unit and a wrapped edge, the support unit composed of a plurality of folded segments stacked in the Z direction is located between the main body portion and the outer wrapped edge. The support unit is formed by bending a partial area of the sealing edge of the encapsulation film and has a certain deformability. The wrapped edge serves to block and protect the support unit. Then, when the battery cell is subjected to an external impact, the support unit elastically supports between the main body portion and the wrapped edge, preventing the external impact force from directly acting on the main body portion, thereby playing a buffering role for the external impact force and reducing the damage suffered by the electrode group inside the main body portion. Moreover, the wrapped edge can prevent the external acting force from directly acting on the support unit and dispersing the support unit, thereby improving the stability and reliability of the entire hemming structure. At the same time, by defining that the ratio W / T of the dimension W of the support unit in the Z direction to the thickness T of the battery cell takes a value within the range of 0.5 to 1, it can not only ensure that the hemming structure can provide sufficient impact resistance for the main body portion and the electrode group, improving the safety of the battery cell, but also avoid the hemming structure occupying too much space in the Z direction and affecting the stacking of the battery cell in the battery pack, thus achieving a balance between the impact resistance effect and the space utilization rate.

[0006] In an optional embodiment, the value range of the dimension W of the support unit in the Z direction is: 1.5 mm ≤ W < 50 mm;

[0007] And / or, the value range of the total thickness T of the main body portion and the electrode group in the Z direction is: 3 mm ≤ T ≤ 50 mm;

[0008] And / or, the distance h1 in the Z direction between the upper surface of the hemming structure and the upper surface of the main body portion, where the value range of h1 is: h1 ≥ 0.1 mm;

[0009] And / or, the distance h2 in the Z direction between the lower surface of the hemming structure and the lower surface of the main body portion, where the value range of h2 is: h2 ≥ 0.1 mm.

[0010] Beneficial effects: By providing that the dimension W of the support unit in the Z direction takes a value within the range of 1.5 mm to 50 mm, the hemming structure can adapt to battery cells of different sizes. It can not only ensure that the hemming structure can provide sufficient impact resistance for the main body portion, thereby improving the safety and reliability of the battery, but also avoid affecting the stacking of the battery cell in the battery pack due to excessive size, improving the space utilization rate inside the battery pack;

[0011] By limiting the total thickness T of the main body and the electrode group in the Z direction to be in the range of 3 mm to 50 mm, that is, limiting the thickness of the battery cell to be in the range of 3 mm to 50 mm, it can not only ensure that the battery cell has sufficient thickness, thus ensuring that the battery cell has sufficient capacity, but also avoid the difficulty in forming the hemming structure or the inability to provide sufficient impact resistance due to the excessive thickness of the battery cell, thereby ensuring the safety of the battery cell;

[0012] By setting the distance h1 between the upper surface of the hemming structure and the upper surface of the main body in the Z direction to be greater than or equal to 0.1 mm, it is ensured that there is a sufficient height difference between the upper surface of the hemming structure and the upper surface of the main body, avoiding the hemming structure from affecting the stacking of the battery cell in the whole package, thereby further improving the space utilization rate inside the battery pack;

[0013] By setting the distance h2 between the lower surface of the hemming structure and the lower surface of the main body in the Z direction to be greater than or equal to 0.1 mm, it is ensured that there is a sufficient height difference between the lower surface of the hemming structure and the lower surface of the main body, further avoiding the hemming structure from affecting the stacking of the battery cell in the whole package.

[0014] In an alternative embodiment, the support unit includes a first connection segment, a first bending portion, and a second bending portion connected in sequence. The head end of the first connection segment is connected to the main body and extends in the X direction. The first bending portion is bent from the tail end of the first connection segment toward the direction close to the main body. The second bending portion is bent from the tail end of the first bending portion toward the direction away from the main body.

[0015] Beneficial effects: By setting the support unit to include a first connection segment, a first bending portion, and a second bending portion connected in sequence, and the first bending portion bulges toward the side away from the main body and the second bending portion bulges toward the side close to the main body, the bending structure formed by the first connection segment, the first bending portion, and the second bending portion has good elastic deformation ability. Thus, when the battery cell is subjected to an external impact force, the bending structure can absorb the impact energy through elastic deformation, playing a buffering effect, avoiding the impact force from being directly transmitted to the electrode group inside the battery cell, and the multi-layer bending design can disperse the impact energy to multiple bending portions, avoiding a single part from bearing too large an impact force, thereby prolonging the service life of the hemming structure and improving the reliability of the hemming structure.

[0016] In an alternative embodiment, the shortest distance between the second bending portion and the main body in the X direction is g1, where 0 ≤ g1 ≤ 0.5 mm;

[0017] And / or, the edge wrapping is connected to the tail end of the second bending portion, and the shortest distance between the first bending portion and the edge wrapping in the X direction is g3, where 0 ≤ g3 ≤ 0.5 mm.

[0018] Beneficial effects: By setting the shortest distance g1 between the second bending part and the main body part in the X direction to be between 0 and 0.5 mm, it is possible to avoid the interference between the second bending part and the main body part, which may cause the second bending part to rebound away from the main body part, thus ensuring the smooth bending and forming of the hemming structure. At the same time, it can also ensure the compactness between the hemming structure and the main body part, improve the support and shaping effect of the hemming structure, and thus ensure the anti-impact effect of the hemming structure.

[0019] By setting the shortest distance g3 between the first bending part and the edge wrapping in the X direction to be between 0 and 0.5 mm, it is possible to avoid the interference between the edge wrapping and the first bending part, which may cause the edge wrapping to rebound away from the main body part, thus ensuring the smooth bending and forming of the hemming structure. At the same time, it can also ensure the compactness of the hemming structure, improve the support and shaping effect of the hemming structure, and thus ensure the anti-impact effect of the hemming structure.

[0020] In an optional embodiment, along the Z direction, the lower surface of the edge wrapping is lower than the lower surface of the first connecting section, or the lower surface of the edge wrapping is flush with the lower surface of the first connecting section. The distance between the lower surface of the edge wrapping and the lower surface of the first connecting section is h4, where 0 ≤ h4 ≤ 3 mm.

[0021] Beneficial effects: By setting the edge wrapping to protrude downward from the lower surface of the supporting unit or be flush with the lower surface of the supporting unit, and defining the dimension h4 of the edge wrapping protruding downward relative to the supporting unit in the Z direction to be between 0 and 3 mm, it is possible to ensure the effectiveness of the anti-impact height formed by the supporting unit on the main body part, ensure the anti-impact effect of the hemming structure, avoid material waste and cost savings, and also avoid the excessive downward extension length of the edge wrapping, which may affect the stacking of the battery cells in the battery pack.

[0022] In an optional embodiment, the supporting unit further includes a folded-back section, which is connected to the end of the edge wrapping and is located between the edge wrapping and the main body part. The folded-back section extends in the X direction and is located below the first connecting section.

[0023] Beneficial effects: By setting the supporting unit to further include a folded-back section connected to the end of the edge wrapping, and the folded-back section is located below the first connecting section, the dimension of the supporting unit in the Z direction is further increased, thereby further increasing the anti-impact height of the hemming structure on the main body part, enhancing the anti-impact effect, and improving the safety of the battery cells.

[0024] In an optional embodiment, the distance between the end of the folded-back section and the main body part in the X direction is g2, where 0 ≤ g2 ≤ 0.5 mm.

[0025] Beneficial effects: By limiting the distance g2 between the end of the folded section and the main body in the X direction to be within the range of 0 to 0.5 mm, it is possible to avoid interference between the folded section and the main body, which may cause the edge wrapping to warp, thus preventing the size of the battery cell in the X direction from being too large and facilitating the stacking of the battery cells in the battery pack. At the same time, when the battery cell is subjected to an external impact, the folded section can effectively support between the edge wrapping and the main body, thereby ensuring the anti-impact effect of the folded edge structure.

[0026] In an alternative embodiment, the encapsulation film is cut from a film body structure. The film body structure includes a pole group area and an air bag. The pole group area is adapted to accommodate the pole group. The air bag is connected to one side of the pole group area in the X direction. The width dimension of the air bag in the X direction is b, the length dimension of the air bag in the Y direction is L, and the battery cell capacity is C. Among them, the relationship between b, L, and C satisfies the formula: 0.006 Ah / mm 2 ≤ C / (b × L) ≤ 0.01 Ah / mm 2 .

[0027] Beneficial effects: By setting the relationship between the battery cell capacity C and the width dimension b of the air bag in the X direction and the length dimension L of the air bag in the Y direction to satisfy 0.006 Ah / mm 2 ≤ C / (b × L) ≤ 0.01 Ah / mm 2 , it can not only ensure that the air bag can accommodate all the gases generated during the formation of the battery cell, thereby ensuring that the gases in the accommodation space of the main body of the battery cell can be exhausted completely, ensuring the quality of the battery cell and improving the safety of the battery cell, but also avoid wasting materials and space due to the oversized air bag.

[0028] In an alternative embodiment, the value range of the width dimension b of the air bag in the X direction is: 3 mm ≤ b ≤ 300 mm;

[0029] and / or, the value range of the length dimension L of the air bag in the Y direction is: 50 mm ≤ L ≤ 1500 mm;

[0030] and / or, the value range of the battery cell capacity C is: 2 Ah ≤ C ≤ 600 Ah;

[0031] and / or, a final seal is provided between the pole group area and the air bag. The pole group area and the final seal form the encapsulation film. The distance h3 between the final seal and the pole group in the X direction is such that 3 mm ≤ h3 ≤ 50 mm.

[0032] Beneficial effects: By setting the width dimension b of the airbag in the range of 3 mm to 300 mm in the X direction, it can not only ensure that the airbag has sufficient width to accommodate the gas generated by the battery cell, avoid the influence of too little gas proportion in the airbag on the exhaust effect, but also avoid wasting space and materials and save costs;

[0033] By setting the distance h3 between the final seal and the electrode group in the X direction in the range of 3 mm to 50 mm, it can not only ensure the smooth formation of the subsequent hemming structure, but also avoid wasting materials and space.

[0034] In a second aspect, the present invention also provides a battery pack, including: an electrode group; the above-mentioned battery cell, and the electrode group is located in the accommodation space of the main body part. Since the battery pack includes the battery cell and has the same effects as the battery cell, they will not be elaborated here. Description of the Drawings

[0035] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0036] Figure 1 It is a schematic structural diagram of a traditional battery cell;

[0037] Figure 2 It is a side view of a battery cell according to an embodiment of the present invention;

[0038] Figure 3 It is Figure 1 A partially enlarged schematic diagram including the hemming structure in

[0039] Figure 4 It is a side view of another battery cell according to an embodiment of the present invention;

[0040] Figure 5 It is Figure 4 A partially enlarged schematic diagram including the hemming structure in

[0041] Figure 6 It is a schematic structural diagram of the assembly of the electrode group and the film body structure according to an embodiment of the present invention after top sealing and side sealing;

[0042] Figure 7 It is Figure 6 A schematic structural diagram of the assembly structure of the electrode group and the film body structure shown in after final sealing;

[0043] Figure 8 It is Figure 7 A schematic structural diagram of the assembly structure of the electrode group and the film body structure shown in after cutting.

[0044] Description of reference numerals:

[0045] 1. Pole group; 2. Main body; 201. First punching hole; 202. Second punching hole; 3. Folding edge structure; 301. First connecting section; 302. First bending section; 303. Second bending section; 304. Second connecting section; 305. Edge wrapping; 306. Folding section; 300. Edge sealing; 4. Membrane structure; 401. Pole group area; 402. Air bag; 403. Final seal; 404. Top seal; 405. Side seal; 5. Pole ear; 6. Seal. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0047] like Figure 1 As shown, the edge sealing 300 of the traditional battery cell is simply bent upward once, which has no anti-collision effect and insufficient protection for the electrode group. The structure of the edge sealing 300 is improved in this embodiment.

[0048] Combine the following Figures 2 to 8 , describing an embodiment of the present invention.

[0049] According to an embodiment of the present invention, on the one hand, a battery cell is provided, such as Figures 2 to 5 As shown, the battery cell includes: an electrode group 1 and a packaging film. The packaging film includes a main body 2 and a folding structure 3. The main body 2 has a closed accommodating space, and the accommodating space is suitable for accommodating the electrode group. The total thickness of the main body 2 and the electrode group 1 along the Z direction is T; the folding structure 3 is connected to at least one side of the main body 2 along the X direction. The folding structure 3 includes a support unit and a rim 305. The support unit includes a plurality of folded sections stacked along the Z direction. The rim 305 is located along the X direction on the side of the support unit away from the main body 2. The size of the support unit along the Z direction is W, wherein W and T satisfy the relationship: 0.5≤W / T<1. Wherein, the X direction is Figures 2 to 5 The X direction in the rectangular coordinate system is Figures 2 to 5 The Z direction in the rectangular coordinate system in , the X direction is perpendicular to the Z direction; the total thickness of the main body 2 and the electrode group 1 along the Z direction is the thickness of the battery cell; the units of W and T are both mm.

[0050] It should be noted that the support unit is supported between the main body 2 and the edge wrapping 305 and has an impact resistance function. In the Z direction, the size of the support unit is the range that the support unit can cover the main body 2, that is, the range where the support part can provide impact resistance protection for the main body 2. If W / T is less than 0.5, the size of the support unit in the Z direction is too small relative to the thickness of the battery cell, the impact resistance effect is not obvious, the area not covered by the support unit is too large, and the impact force on the electrode sheet corresponding to this area in the electrode group is too large, which is likely to cause the dislocation of the electrode sheet, resulting in an internal short circuit of the battery cell; if W / T is too large, the size of the support unit in the Z direction is too large relative to the thickness of the battery cell, affecting the stacking of the battery cell in the whole package.

[0051] For the battery cell of this embodiment, by setting the encapsulation film to include a main body 2 for accommodating the electrode group and a folding edge structure 3 connected to at least one side of the main body 2, and setting the folding edge structure 3 to include a support unit and an edge wrapping 305, the support unit composed of a plurality of folding segments stacked in the Z direction is located between the main body 2 and the outer edge wrapping 305. The support unit is formed by bending a partial area of the sealing edge of the encapsulation film and has a certain deformability. The edge wrapping 305 plays a role in blocking and protecting the support unit. Then, when the battery cell is subjected to an external impact, the support unit elastically supports between the main body 2 and the edge wrapping 305, avoiding the direct action of the external impact force on the main body 2, thereby playing a buffering role for the external impact force and reducing the damage suffered by the electrode group 1 inside the main body 2. Moreover, the edge wrapping 305 can prevent the external force from directly acting on the support unit and dispersing the support unit, thereby improving the stability and reliability of the entire folding edge structure 3. At the same time, by limiting the ratio W / T of the size W of the support unit in the Z direction to the thickness T of the battery cell to take values within the range of 0.5 to 1, it can not only ensure that the folding edge structure 3 can provide sufficient impact resistance for the main body 2 and the electrode group 1, improving the safety of the battery cell, but also avoid the folding edge structure 3 occupying too much space in the Z direction and affecting the stacking of the battery cell in the battery pack, thus achieving the balance between the impact resistance effect and the space utilization rate.

[0052] In one embodiment, further combined with Figures 2 to 5 As shown, the folding edge structure 3 is connected to one side of the main body 2 in the X direction. Specifically, the folding edge structure 3 is connected to the right side of the main body 2. The folding edge structure 3 can provide impact resistance, which means that it can buffer the impact force from right to left. Among them, left and right refer to Figures 2 to 5 the "left" and "right" directions indicated by the arrows in

[0053] In one embodiment, the value range of the dimension W of the support unit in the Z direction is: 1.5 mm ≤ W < 50 mm. W is the height of the impact-resistant contact surface. If W is less than 1.5 mm, the dimension of the support unit in the Z direction is too small, and the impact-resistant effect is not obvious; if W is greater than or equal to 50 mm, the dimension of the support unit in the Z direction is too large, wasting materials and affecting the stacking of the battery cells in the battery pack. Therefore, by setting the dimension W of the support unit in the range of 1.5 mm to 50 mm in the Z direction, the folding edge structure 3 can adapt to battery cells of different sizes, which can not only ensure that the folding edge structure 3 can provide sufficient impact resistance for the main body 2, thereby improving the safety and reliability of the battery, but also avoid affecting the stacking of the battery cells in the battery pack due to excessive size, and improve the space utilization rate in the battery pack.

[0054] In one embodiment, the value range of the total thickness T of the main body 2 and the electrode group 1 in the Z direction is: 3 mm ≤ T ≤ 50 mm. It should be noted that the total thickness T of the main body 2 and the electrode group 1 in the Z direction is the thickness of the battery cell. Further combined with Figures 2 to 5 As shown, T is the vertical distance between the upper surface and the lower surface of the main body 2, where the upper surface refers to Figure 3 and Figure 5 the surface in the direction of "up" pointed by the arrow in Figure 3 and Figure 5 the lower surface refers to the surface in the direction of "down" pointed by the arrow in

[0055] If T is greater than 50 mm, in order to ensure a suitable value of W / T, it is necessary to correspondingly increase the value of W, which will increase the forming difficulty of the folding edge structure 3 and it is also difficult to ensure its stability in the Z direction.

[0056] In one embodiment, the distance in the Z direction between the upper surface of the folding edge structure 3 and the upper surface of the main body 2 is h1, where the value range of h1 is: h1 ≥ 0.1 mm. Among them, the upper surface refers to Figure 3 and Figure 5The surface in the direction of "up" pointed by the arrow in the figure. The hemming structure 3 is arranged on the side of the main body 2. If h1 is less than 0.1 mm, the height difference between the upper surface of the hemming structure 3 and the upper surface of the main body 2 is too small, which affects the stacking of the battery cells in the battery pack. Therefore, by setting the distance h1 in the Z direction between the upper surface of the hemming structure 3 and the upper surface of the main body 2 to be greater than or equal to 0.1 mm, it is ensured that there is a sufficient height difference between the upper surface of the hemming structure 3 and the upper surface of the main body 2, avoiding the hemming structure 3 from affecting the stacking of the battery cells in the whole pack, thereby further improving the space utilization rate inside the battery pack.

[0057] In one embodiment, the distance in the Z direction between the lower surface of the hemming structure 3 and the lower surface of the main body 2 is h2, where the value range of h2 is: h2≥0.1 mm. Among them, the lower surface refers to Figure 3 and Figure 5 the surface in the direction of "down" pointed by the arrow in the figure. By setting the distance h2 in the Z direction between the lower surface of the hemming structure 3 and the lower surface of the main body 2 to be greater than or equal to 0.1 mm, it is ensured that there is a sufficient height difference between the lower surface of the hemming structure 3 and the lower surface of the main body 2, further avoiding the hemming structure 3 from affecting the stacking of the battery cells in the whole pack.

[0058] In one embodiment, the support unit includes a first connection segment 301, a first bending portion 302 and a second bending portion 303 connected in sequence. The head end of the first connection segment 301 is connected to the main body 2 and extends along the X direction. The first bending portion 302 is bent from the end of the first connection segment 301 towards the direction close to the main body 2. The second bending portion 303 is bent from the end of the first bending portion 302 towards the direction away from the main body 2. Among them, the first connection segment 301, the first bending portion 302 and the second bending portion 303 are arranged in sequence from bottom to top to form a bending structure; the first bending portion 302 is connected to one end of the first connection segment 301 away from the main body 2 and protrudes towards the side away from the main body 2. The side of the first bending portion 302 away from the main body 2 along the X direction is the position farthest from the main body 2 on the bending structure; the second bending portion 303 is connected to the side of the first bending portion 302 close to the main body 2 and protrudes towards the side close to the main body 2 along the X direction. The end of the second bending portion 303 is directly or indirectly connected to the head end of the edge wrapping 305.

[0059] By setting a supporting unit including a first connecting section 301, a first bending portion 302 and a second bending portion 303 which are connected in sequence, and the first bending portion 302 protrudes toward a side away from the main body 2, and the second bending portion 303 protrudes toward a side close to the main body 2, the bending structure formed by the first connecting section 301, the first bending portion 302 and the second bending portion 303 has good elastic deformation ability, so that when the battery cell is subjected to external impact force, the bending structure can absorb the impact energy through elastic deformation, play a buffering effect, and avoid the impact force being directly transmitted to the pole group 1 inside the battery cell, and the multi-layer bending design can disperse the impact energy to multiple bending portions, avoid a single part from being subjected to excessive impact force, thereby extending the service life of the folding structure 3 and improving the reliability of the folding structure 3.

[0060] In one embodiment, the first bending portion 302 and the second bending portion 303 are both arc segments, and the overall bending structure formed by the second bending portion 303, the first bending portion 302 and the first connecting segment 301 is "S"-shaped in the XZ plane. The arc shape is easy to form, can bend smoothly, and has a smooth transition, which can avoid the stress concentration phenomenon caused by the right-angle transition, thereby further improving the impact resistance of the folding structure 3.

[0061] In one embodiment, the support unit further includes a second connecting section 304, which extends along the X direction and is connected between the second bending portion 303 and the edge 305 to ensure that the edge 305 can be located on the side of the first bending portion 302 away from the main body 2, avoiding interference between the edge 305 and the first bending portion 302, thereby ensuring smooth formation of the edge structure 3. The first connecting section 301, the first bending portion 302, the second bending portion 303, the second connecting section 304 and the edge 305 are bent and stacked on one side of the battery cell, which has a good buffering effect.

[0062] In one embodiment, the shortest distance between the second bend 303 and the main body 2 along the X direction is g1, where 0≤g1≤0.5mm. It should be noted that the second bend 303 is in an arc shape, and the center of the arc is located on the side of the second bend 303 away from the main body 2. The shortest distance between the second bend 303 and the main body 2 along the X direction refers to the vertical distance between the leftmost side of the second bend 303 and the main body 2, where the left refers to Figures 2 to 5 The middle arrow points to the direction of "left". When g1=0, it means that the second bend 303 is just in contact with the main body 2. If g1 is less than 0, the second bend 303 interferes with the main body 2, causing the second bend 303 to rebound away from the main body 2, affecting the folding formation. If g1 is greater than 0.5mm, the folding structure 3 is too loose with the main body 2. When the battery cell is subjected to external impact force, the folding structure 3 has a poor shaping support effect and a poor anti-impact effect.

[0063] Therefore, by setting the shortest distance g1 between the second bending portion 303 and the main body portion 2 in the X direction to be between 0 and 0.5 mm, it is possible to avoid the interference between the second bending portion 303 and the main body portion 2, which may cause the second bending portion 303 to rebound away from the main body portion 2, thus ensuring the smooth bending and forming of the hemming structure 3. At the same time, the compactness between the hemming structure 3 and the main body portion 2 can be ensured, and the support and shaping effect of the hemming structure 3 can be improved, thereby ensuring the anti-impact effect of the hemming structure 3.

[0064] In one embodiment, the hemming 305 is connected to the end of the second bending portion 303. The shortest distance g3 between the first bending portion 302 and the hemming 305 in the X direction satisfies 0 ≤ g3 ≤ 0.5 mm. It should be noted that the first bending portion 302 is arc-shaped, and the center of the arc is located on the side of the first bending portion 302 facing the main body portion 2. The shortest distance between the first bending portion 302 and the hemming 305 in the X direction refers to the vertical distance between the rightmost side of the first bending portion 302 and the hemming 305, where "right" refers to Figures 2 to 5 the direction of "right" indicated by the arrow in the figure. If g3 is less than 0, the first bending portion 302 interferes with the hemming 305, causing the hemming 305 to rebound away from the main body portion 2 and the hemming 305 to warp, affecting the hemming forming. If g3 is greater than 0.5 mm, the distance between the first bending portion 302 and the hemming 305 is too large, and the hemming structure 3 is too loose. When the battery cell is subjected to an external impact force, the shaping and supporting effect of the hemming structure 3 is poor.

[0065] Therefore, by setting the shortest distance g3 between the first bending portion 302 and the hemming 305 in the X direction to be between 0 and 0.5 mm, it is possible to avoid the interference between the hemming 305 and the first bending portion 302, which may cause the hemming 305 to rebound away from the main body portion 2, thus ensuring the smooth bending and forming of the hemming structure 3. At the same time, the compactness of the hemming structure 3 can be ensured, and the support and shaping effect of the hemming structure 3 can be improved, thereby ensuring the anti-impact effect of the hemming structure 3.

[0066] Preferably, the hemming 305 extends in the Z direction, avoiding the hemming 305 from warping away from the main body portion 2 and increasing the size of the battery cell in the X direction, thereby facilitating the stacking of the battery cells in the battery pack.

[0067] Optionally, when the extension length of the first connecting section 301 in the X direction is relatively large, a third connecting section can also be provided between the first bending portion 302 and the second bending portion 303. The third connecting section extends in the X direction, and the first bending portion 302 and the second bending portion 303 are connected by the third connecting section, which can prevent the second bending portion 303 from being too far away from the main body portion 2 and avoid the hemming structure 3 from being too loose. The length of the third connecting section in the X direction is adjusted adaptively according to the length of the first connecting section 301.

[0068] In one embodiment, further combined with Figures 2 to 3 As shown, along the Z direction, the lower surface of the edge wrapping 305 is lower than the lower surface of the first connecting section 301, or the lower surface of the edge wrapping 305 is flush with the lower surface of the first connecting section 301. The distance between the lower surface of the edge wrapping 305 and the lower surface of the first connecting section 301 is h4, where 0 ≤ h4 ≤ 3 mm. Among them, the lower surface refers to Figures 2 to 3 the surface in the direction indicated by the arrow "down" in

[0069] In this embodiment, the support unit is composed of the first connecting section 301, the first bending portion 302, the second bending portion 303 and the second connecting section 304. The lower surface of the first connecting section 301 is the lowest surface of the support unit. The edge wrapping 305 is located on the side of the support unit away from the main body portion 2. The edge wrapping 305, as the outermost folding section on the hemming structure 3, has a protective effect. During the process of the battery cell being impacted externally, the edge wrapping 305 first contacts the impact force, and then the edge wrapping 305 presses against the support unit, transmits the force to the support unit, and then the support unit presses against the main body portion 2, and then acts on the main body portion 2 with the buffered force. The edge wrapping 305 and the support unit jointly play a buffering role; if h4 is less than 0, the lower surface of the edge wrapping 305 is higher than the lower surface of the first connecting section 301, which will affect the effectiveness of the dimension W of the support unit in the Z direction, the height of the anti-collision contact surface will be reduced, and the anti-impact effect of the hemming structure 3 on the main body portion 2 will be weakened. If h4 is greater than 3 mm, the edge wrapping 305 protrudes too long relative to the support unit in the Z direction, wasting materials.

[0070] Therefore, by setting the edge wrapping 305 to protrude downward from the lower surface of the support unit or be flush with the lower surface of the support unit, and limiting the dimension h4 of the edge wrapping 305 protruding downward relative to the support unit in the Z direction to take values between 0 and 3 mm, it can not only ensure the effectiveness of the anti-impact height formed by the support unit on the main body portion 2 and ensure the anti-impact effect of the hemming structure 3, but also avoid wasting materials and saving costs, and can also avoid the edge wrapping 305 extending too long downward and affecting the stacking of the battery cells in the battery pack.

[0071] It should be noted that the encapsulation film is formed by buckling the first film body and the second film body. The first film body has a first punching pit 201, and the second film body has a second punching pit 202. After the first film body and the second film body are buckled, the first punching pit 201 and the second punching pit 202 are opposite to each other and form the main body part 2. Among them, the depression depth of the first punching pit 201 in the Z direction is greater than the depression depth of the second punching pit 202 in the Z direction, that is, the total dimension of the first film body in the Z direction is greater than the total dimension of the second film body in the Z direction. Further combined with Figure 3 as shown, the first film body is located above the second film body. The first bending part 302 is bent upward from the end of the first connecting section 301, and the second bending part 303 is bent upward from the end of the first connecting section 301. The support unit composed of the first connecting section 301, the first bending part 302 and the second bending part 303 corresponds to the first film body with a larger dimension in the Z direction, ensuring that the anti-impact height of the support unit covers as much height range on the main body part 2 as possible, so as to ensure the anti-impact effect of the folded edge structure 3.

[0072] In addition, in other embodiments, further combined with Figures 4 to 5 as shown, the support unit further includes a folded-back section 306. The folded-back section 306 is connected to the end of the edge wrapping 305 and is located between the edge wrapping 305 and the main body part 2. The folded-back section 306 extends in the X direction and is located below the first connecting section 301. It should be noted that the folded-back section 306 is folded back from the end of the edge wrapping 305 towards the direction of the main body part 2, and the folded-back section 306 is located below the first connecting section 301. In this embodiment, the support unit is composed of the first connecting section 301, the first bending part 302, the second bending part 303, the second connecting section 304 and the folded-back section 306. Then the folded-back section 306 is located at the lowermost side of the support unit, and the lower surface of the folded-back section 306 is the lower surface of the folded edge structure 3. By setting that the support unit further includes a folded-back section 306 connected to the end of the edge wrapping 305 and the folded-back section is located below the first connecting section 301, the dimension of the support unit in the Z direction is further increased, thereby further increasing the anti-impact height of the folded edge structure 3 on the main body part 2, increasing the anti-impact effect, and improving the safety of the battery cell.

[0073] Among them, the folded-back section 306 corresponds to the second film body and can provide protection for the part of the electrode group wrapped by the second film body, thereby further increasing the anti-impact protection range of the folded edge structure 3 for the electrode group.

[0074] In one embodiment, the distance between the end of the folded section 306 and the main body 2 in the X direction is g2, where 0 ≤ g2 ≤ 0.5 mm. Here, the end of the folded section 306 refers to the end of the folded section 306 that is far from the edge wrapping 305. The end of the folded section 306 is disposed close to the main body 2. When g2 is equal to 0, the folded section 306 just abuts against the side surface of the main body 2. If g2 is less than 0, the folded section 306 interferes with the main body 2, causing the lower end of the edge wrapping 305 to warp away from the main body 2, making the edge wrapping 305 unable to be flattened, affecting the force direction of the folded edge structure 3 under the action of an external impact force, thereby affecting the anti-impact effect, and also increasing the size of the battery cell in the X direction. If g2 is greater than 0.5 mm, the end of the folded section 306 is too far from the main body 2. When the battery cell is subjected to an external impact, the folded section 306 has no supporting effect, which will reduce the anti-impact height of the supporting unit and weaken the buffering effect.

[0075] Therefore, by limiting the value of the distance g2 between the end of the folded section 306 and the main body 2 in the X direction to be within the range of 0 to 0.5 mm, it is possible to avoid the interference between the folded section 306 and the main body 2, which causes the edge wrapping 305 to warp, thereby avoiding an excessive size of the battery cell in the X direction and facilitating the stacking of the battery cells in the battery pack. At the same time, it can ensure that when the battery cell is subjected to an external impact, the folded section 306 can effectively support between the edge wrapping 305 and the main body 2, thereby ensuring the anti-impact effect of the folded edge structure 3.

[0076] In one embodiment, the folded section 306 and the edge wrapping 305 are connected by a rounded corner transition. The second connecting section 304 and the edge wrapping 305 are connected by a rounded corner transition. The second connecting section 304, the edge wrapping 305 and the folded section 306 are integrally wrapped around the outside of the first connecting section 301, the first bending portion 302 and the second bending portion 303 in a "U" shape, making the appearance of the folded edge structure 3 neat, without protruding parts, having a compact structure, good anti-impact effect, and facilitating the stacking of the battery cells in the battery pack.

[0077] In one embodiment, after the folded edge structure 3 is bent and formed, it is bundled with a tape to improve the compactness and stability of the folded edge structure 3. On the one hand, it can reduce the overall size of the battery cell, and on the other hand, it can increase the buffering effect of the folded edge structure 3 against mechanical impact.

[0078] In one embodiment, further combined Figures 6 to 8 As shown, the encapsulation film is cut from the film body structure 4. The film body structure 4 includes a pole group area 401 and an air bag 402. The pole group area 401 is adapted to accommodate the pole group 1. The air bag 402 is connected to one side of the pole group area 401 in the X direction. The width dimension of the air bag 402 in the X direction is b, the length dimension of the air bag 402 in the Y direction is L, and the battery cell capacity is C. Among them, the relationship between b, L, and C satisfies the formula: 0.006 Ah / mm 2≤C / (b×L)≤0.01 Ah / mm 2 Among them, the X direction refers to Figures 6 to 8 the X direction in the rectangular coordinate system shown, and the Y direction refers to Figures 6 to 8 the Y direction in the rectangular coordinate system shown. It should be noted that the airbag 402 is used to hold the gas generated during the formation of the battery cell. The gas generation amount of the battery cell is related to the capacity C of the battery cell. The larger the capacity of the battery cell, the more gas is generated; b×L reflects the capacity size of the airbag 402; if C / (b×L) is less than 0.006 Ah / mm 2 , then the capacity of the battery cell is too small relative to the capacity of the airbag 402, and the designed size of the airbag 402 is excessive, wasting materials and space; if C / (b×L) is greater than 0.01 Ah / mm 2 , then the capacity of the battery cell is too large relative to the capacity of the airbag 402, and the designed size of the airbag 402 is insufficient. The airbag 402 cannot hold all the gas generated by the battery cell, which is not conducive to exhausting the gas in the accommodation space of the battery cell main body 2, and will affect the quality of the battery cell.

[0079] Therefore, by setting that the relationship between the battery cell capacity C, the width dimension b of the airbag 402 in the X direction, and the length dimension L of the airbag 402 in the Y direction satisfies 0.006 Ah / mm 2 ≤C / (b×L)≤0.01 Ah / mm 2 , it can not only ensure that the airbag 402 can hold all the gas generated during the formation of the battery cell, so as to ensure that the gas in the accommodation space of the battery cell main body 2 can be exhausted, ensure the quality of the battery cell, improve the safety of the battery cell, but also avoid wasting materials and space due to the oversize of the airbag 402.

[0080] In one embodiment, the value range of the width dimension b of the airbag 402 in the X direction is: 3 mm ≤ b ≤ 300 mm. It should be noted that during the process of exhausting gas into the airbag 402, not only gas enters the airbag 402, but also a small amount of residual electrolyte will flow into the airbag 402. If the width dimension b of the airbag 402 in the X direction is less than 3 mm, the width dimension of the airbag 402 is too small, and the proportion of gas in the airbag 402 is too small, resulting in poor exhaust effect; if b is greater than 300 mm, the width dimension of the airbag 402 is too large, wasting space and materials. Therefore, by setting the width dimension b of the airbag 402 to take values in the range of 3 mm to 300 mm, it can not only ensure that the airbag 402 has enough width dimension to hold the gas generated by the battery cell, avoid the influence of too small gas proportion in the airbag 402 on the exhaust effect, but also avoid wasting space and materials and save costs.

[0081] In one embodiment, the length dimension L of the airbag 402 in the Y direction ranges from 50 mm to 1500 mm. The length dimension L of the airbag 402 in the Y direction is equal to the length dimension of the battery cell in the Y direction. 50 mm to 1500 mm is the length of a conventional battery cell. By setting the length dimension L of the airbag 402 in the range of 50 mm to 1500 mm, a suitable length dimension of the battery cell is ensured, thereby guaranteeing the performance of the battery cell.

[0082] In one embodiment, the value range of the battery cell capacity C is: 2 Ah ≤ C ≤ 600 Ah. By limiting the value range of the battery cell capacity C to be within 2 Ah to 600 Ah, it can not only ensure that the battery cell has sufficient capacity, but also avoid increasing the risk due to an overly large battery cell capacity.

[0083] In one embodiment, a final seal 403 is provided between the electrode group area 401 and the airbag 402. The electrode group area 401 and the final seal 403 form a packaging film. The distance h3 between the final seal 403 and the electrode group 1 in the X direction is such that 3 mm ≤ h3 ≤ 50 mm. It should be noted that after the final seal 403 is processed, the airbag 402 needs to be cut off to form a preliminary battery cell as shown in Figure 8 The side corresponding to the final seal 403 is used to be bent into a folded edge structure 3. If h3 is less than 3 mm, the distance between the final seal 403 and the electrode group 1 in the X direction is too small, and the structural dimension available for folding in the end is too short, making it inconvenient to form the impact-resistant folded edge structure 3. If h3 is greater than 50 mm, the distance between the final seal 403 and the electrode group 1 is too large, wasting materials and space. Therefore, by setting the distance h3 between the final seal 403 and the electrode group 1 in the X direction within the range of 3 mm to 50 mm, it can not only ensure the smooth formation of the subsequent folded edge structure 3, but also avoid wasting materials and space.

[0084] It should be noted that the battery cell is a soft-pack battery cell. During the manufacturing process of the battery cell, after the electrode group 1 and the electrode tab 5 are welded and installed in the film structure 4, the film structure 4 is first top-sealed to form a top seal 404 on the side of the film structure 4 corresponding to the electrode tab 5; then one side of the film structure 4 is side-sealed to form a side seal 405 on the side closer to the electrode group 1 among the two sides of the film structure 4 where the electrode tab 5 is not provided. Then, after injecting liquid and evacuating the air from the other side, a vacuum packaging is carried out to form a side seal 405 on the other side, thus forming a semi-finished battery cell as shown in Figure 6 After that, with the battery cell undergoing charge and discharge cycles, after the SEI film is formed and generates gas, the generated gas is driven into the airbag 402, and then a second-stage final seal is carried out to form a final seal 403 between the electrode group area 401 and the airbag 402, forming a structural form as shown in Figure 7 Finally, the airbag 402 is cut off to form as shown inFigure 8 The battery cell shown

[0085] Wherein, at a position corresponding to the top seal 404, a seal 6 is provided between the tab 5 and the packaging film. The seal 6 is preferably PP glue, which facilitates heat sealing between the tab 5 and the packaging film and ensures the sealing performance after heat sealing. Preferably, the packaging film is an aluminum-plastic film.

[0086] In the battery cell of this embodiment, a form of the hemming structure 3 is designed to achieve the anti-collision protection function of the battery cell in the whole package, avoid damage to the battery cell, thereby improving the product quality of the soft-pack battery; avoid the risk of failure during use; and also limit the parameters of the air bag 402 corresponding to battery cells of different capacities, avoiding the situation where the exhaust gas is not completely discharged and affecting the quality of the battery cell, as well as the situation where the electrolyte contaminates the tooling during exhaust.

[0087] Battery cells are designed with different parameters and tested to verify the influence of different parameters on the battery cells. The following describes the influence of different values of W / T and C / (b×L) on the battery cells.

[0088] Table 1 Influence of different parameter values on the battery cell

[0089]

[0090] It can be seen from Table 1 that for the battery cells of Embodiment 1 to Embodiment 4, the values of C / (b×L) are all within the range of 0.006 Ah / mm 2 to 0.01 Ah / mm 2 That is, the values of C / (b×L) are all within the limited range of this application, and the battery cells do not fail, that is, the air bag 402 can accommodate all the gases generated during the formation of the battery cell. After the battery cell is formed and exhausted, the battery cell does not bulge and can exhaust all the gases generated inside the main body 2 of the battery cell; while for the battery cell of Comparative Case 1, C / (b×L) is 0.012 Ah / mm 2 , exceeding the upper limit and not within the limited range of this application, resulting in problems such as the battery cell bulging and being unable to exhaust all the gases generated inside the main body 2 of the battery cell.

[0091] In addition, if C / (b×L) is less than 0.006 Ah / mm 2 , that is, exceeding the lower limit, although the air bag 402 can accommodate all the gases generated during the formation of the battery cell, the designed size of the air bag 402 is excessive, wasting materials and space. It can be seen from this that when the battery cell capacity C, the width dimension b of the air bag 402 along the X direction, and the length dimension L of the air bag 402 along the Y direction satisfy 0.006 Ah / mm 2 ≤C / (b×L)≤0.01 Ah / mm 2The relational expression can not only ensure that the airbag 402 can accommodate all the gases generated during the formation of the battery cell, thereby ensuring that the gases in the accommodation space of the main body 2 of the battery cell can be completely discharged, ensuring the quality of the battery cell and improving the safety of the battery cell, but also avoid wasting materials and space due to the oversized size of the airbag 402.

[0092] It can also be seen from Table 1 that for the battery cells of Embodiment 1 to Embodiment 4, the value of W / T is within the range of 0.5 to 1. The value of W / T is within the range defined in this application, and the battery cells do not fail, that is, the battery cells do not short-circuit after the impact test, the internal electrode sheets of the battery cells are not misaligned, and the battery cells are stacked flat in the battery pack; for the battery cell of Comparative Case 2, W / T is 0.48, less than 0.5, and W / T exceeds the lower limit and is not within the range defined in this application. After the impact test of the battery cell, the battery cell has a short-circuit abnormality, and CT confirms that the internal electrode sheets are misaligned; for the battery cell of Comparative Case 3, W / T is 1.1, greater than 1, and W / T exceeds the upper limit and is not within the range defined in this application, resulting in problems such as abnormal stacking of the battery cell in the package, uneven stacking, and difficulty in packaging.

[0093] It can be seen from this that when the ratio W / T of the dimension W of the support unit in the Z direction to the thickness T of the battery cell takes a value within the range of 0.5 to 1, it can not only ensure that the flanging structure 3 can provide sufficient anti-impact effect for the main body 2 and the electrode group 1, improving the safety of the battery cell, but also avoid the flanging structure 3 occupying too much space in the Z direction and affecting the stacking of the battery cell in the battery pack, thereby achieving a balance between the anti-impact effect and the space utilization rate.

[0094] According to an embodiment of the present invention, on the other hand, a battery pack is also provided, including: an electrode group and the above-mentioned battery cell, and the electrode group is located in the accommodation space of the main body 2. Preferably, the number of battery cells is multiple; the battery cells are lithium-ion battery cells.

[0095] Although the embodiments of the present 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 present 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: Pole group; A packaging film comprises a main body and a folding structure, wherein the main body has a sealed accommodating space, the accommodating space is suitable for accommodating the electrode group, and the total thickness of the main body and the electrode group along the Z direction is T; the folding structure is connected to at least one side of the main body along the X direction, the folding structure comprises a supporting unit and a folding edge, the supporting unit comprises a plurality of folded segments stacked along the Z direction, the folding edge is located along the X direction on a side of the supporting unit away from the main body, and the size of the supporting unit along the Z direction is W, wherein W and T satisfy the relationship: 0.5≤W / T<1.

2. The battery cell according to claim 1, characterized in that: The dimension W of the support unit along the Z direction has a value range of: 1.5 mm ≤ W < 50 mm; And / or, the total thickness T of the main body and the pole group along the Z direction is in the range of: 3mm≤T≤50mm; And / or, the distance between the upper surface of the folding structure and the upper surface of the main body along the Z direction is h1, wherein the value range of h1 is: h1 ≥ 0.1 mm; And / or, the distance between the lower surface of the folding structure and the lower surface of the main body along the Z direction is h2, wherein the value range of h2 is: h2≥0.1mm.

3. The battery cell according to claim 1, characterized in that: The support unit includes a first connecting section, a first bending portion and a second bending portion connected in sequence, the head end of the first connecting section is connected to the main body and extends along the X direction, the first bending portion is formed by bending the end of the first connecting section toward a direction close to the main body, and the second bending portion is formed by bending the end of the first bending portion toward a direction away from the main body.

4. The battery cell according to claim 3, characterized in that: The shortest distance between the second bending portion and the main body along the X direction is g1, where 0≤g1≤0.5mm; And / or, the edge binding is connected to an end of the second bending portion, and the shortest distance between the first bending portion and the edge binding along the X direction is g3, wherein 0≤g3≤0.5mm.

5. The battery cell according to claim 3, characterized in that: Along the Z direction, the lower surface of the edging is lower than the lower surface of the first connecting section, or the lower surface of the edging is flush with the lower surface of the first connecting section, and the distance between the lower surface of the edging and the lower surface of the first connecting section is h4, where 0≤h4≤3mm.

6. The battery cell according to claim 3, characterized in that: The support unit further includes a folded section, which is connected to an end of the edge and is located between the edge and the main body. The folded section extends along the X direction and is located below the first connecting section.

7. The battery cell according to claim 6, characterized in that: The distance between the end of the folded section and the main body along the X direction is g2, wherein 0≤g2≤0.5mm.

8. The battery cell according to any one of claims 1 to 7, characterized in that: The packaging film is cut from a film structure, the film structure includes a pole group area and an air bag, the pole group area is suitable for accommodating the pole group, the air bag is connected to one side of the pole group area along the X direction, the width of the air bag along the X direction is b, the length of the air bag along the Y direction is L, the battery capacity is C, wherein b, L, C satisfy the relationship: 0.006Ah / mm 2 ≤C / (b×L)≤0.01Ah / mm 2 .

9. The battery cell according to claim 8, characterized in that: The value range of the width dimension b of the air bag along the X direction is: 3mm≤b≤300mm; And / or, the length dimension L of the air bag along the Y direction is in the range of: 50 mm ≤ L ≤ 1500 mm; And / or, the value range of the battery cell capacity C is: 2Ah≤C≤600Ah; And / or, a final seal is provided between the pole group area and the air bag, the pole group area and the final seal constitute the packaging film, and the distance between the final seal and the pole group along the X direction is h3, wherein 3mm≤h3≤50mm.

10. A battery pack, characterized in that: include: Pole group; The battery cell according to any one of claims 1 to 9, wherein the electrode group is located in the accommodating space of the main body.

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