Battery cell and battery pack
By designing the first and second pits connected to the packaging film of the battery cell and limiting their depth relationship, the risk of the packaging film rupture caused by the extreme ear thickness is solved, and a higher sealing ability and lower risk of plastic seal failure is achieved.
Patent Information
- Application Number
- CN202510310877.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-17
- Publication Date
- 2025-06-13
AI Technical Summary
During the packaging process of existing battery cells, the thickness of the electrodes leads to damage to the packaging film structure, which increases the risk of packaging film rupture and plastic seal failure.
The film body of the encapsulating film has a first and a second pit connected to each other, the second pit connected to the side of the first pit and defines the relationship between its depression depth T1 and the maximum size t2 of the pole ear structure to 0.8≤2T1/t2≤1.1 to provide a reasonable accommodation space and reduce tension deformation.
Through the reasonably designed pit structure, the step stretch deformation of the packaging film in the extreme ear area and the fold after hot pressing are avoided, the sealing property is improved, and the risk of plastic seal failure of the packaging film is reduced.
Smart Images
Figure CN120149671A_ABST
Abstract
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] A battery cell mainly consists of a tab, an electrode assembly, and a packaging film. Among them, the packaging film encapsulates the electrode assembly and the tab, and is sealed by hot pressing. The packaging film has certain strength and toughness, playing a role in protecting the electrode assembly and the tab. In the prior art, usually, a pit is first punched on the packaging film to process a concave pit for accommodating the electrode assembly, and then the electrode assembly is placed in the concave pit for assembly with the packaging film.
[0003] However, due to the certain thickness of the tab, during the encapsulation process of the packaging film, tensile deformation will occur at the position corresponding to the side of the tab on the packaging film, damaging the structure of the packaging film. During the long-term use of the battery cell, there is a high risk of plastic sealing failure caused by the rupture of the packaging film in the tab area. Summary of the Invention
[0004] In view of this, the present invention provides a battery cell and a battery pack to solve the problem of high risk of plastic sealing failure in the tab area of the packaging film.
[0005] In a first aspect, the present invention provides a battery cell, including: a packaging film, including two film bodies that are buckled with each other, and each film body is provided with a first concave pit and a second concave pit, the second concave pit is connected to the side of the first concave pit, and the depression depth of the second concave pit along the thickness direction of the film body is T1; an electrode assembly, disposed between the two film bodies, and the electrode assembly is located in the first concave pit; a tab structure, one end of the tab structure is connected to the side of the electrode assembly and the other end extends out of the packaging film, and a partial area of the tab structure close to the electrode assembly is located in the second concave pit, the maximum dimension of the tab structure along its thickness direction is t2, where 0.8 ≤ 2T1 / t2 ≤ 1.1.
[0006] Beneficial effects: By providing a first concave pit and a second concave pit that are connected to each other on the film body of the packaging film, the film body not only has a space for accommodating the electrode assembly but also has a space for accommodating the tab structure. At the same time, by defining that the depression depth T1 of the second concave pit and the maximum dimension t2 of the tab structure along its thickness direction satisfy the relationship of 0.8 ≤ 2T1 / t2 ≤ 1.1, the second concave pit has a reasonable depression depth, which can avoid serious stepped tensile deformation at the position corresponding to the edge of the tab structure on the film body due to the second concave pit not providing enough accommodation space for the tab structure along the thickness direction, thereby avoiding excessive damage to the film body, and can also avoid wrinkles generated after hot pressing due to the excessive size of the second concave pit along the thickness direction, thereby ensuring the sealing performance and reducing the risk of plastic sealing failure of the packaging film.
[0007] In an alternative embodiment, the maximum dimension t2 of the tab structure in its thickness direction ranges from 0.2 mm to 20 mm;
[0008] and / or, the depression depth T1 of the second pit in the thickness direction of the film body ranges from 0.2 mm to 10 mm.
[0009] Beneficial effects: By setting the maximum dimension t2 of the tab structure in the range of 0.2 mm to 20 mm in its thickness direction, it can not only ensure the necessity of setting the second pit on the encapsulation film and ensure the safety during the charge and discharge process of the battery cell, but also facilitate the processing of the second pit and avoid excessive weight of the tab structure, thus being beneficial to improving the energy density of the battery cell;
[0010] By setting the depression depth T1 of the second pit in the range of 0.2 mm to 10 mm, it can not only avoid unnecessary pit punching, reduce the processing difficulty, provide sufficient accommodation space for the tab structure in the thickness direction, but also avoid wrinkles generated after hot pressing due to excessive size of the second pit in the thickness direction, thus ensuring the sealing performance and reducing the risk of plastic sealing failure of the encapsulation film.
[0011] In an alternative embodiment, the tab structure includes a tab body and a seal, the seal is attached to the surface of the tab body, and the total thickness of the tab body and the seal is the maximum dimension of the tab structure in its thickness direction.
[0012] Beneficial effects: By attaching a seal to the surface of the tab body, it can ensure the insulation between the tab body and the encapsulation film, and facilitate heat sealing between the tab structure and the encapsulation film, ensuring the sealing performance after encapsulation.
[0013] In an alternative embodiment, the depression depth of the first pit in the thickness direction of the film body is T0, where 0.1 ≤ T1 / T0 ≤ 0.6.
[0014] Beneficial effects: It can not only ensure that the second pit can provide sufficient accommodation space for the tab structure in the thickness direction and avoid heat sealing failure, but also avoid excessive tensile force on the fillet surface at the junction of the first pit and the second pit, thus avoiding cracking and damage of the film body and further ensuring the sealing performance after encapsulation.
[0015] In an alternative embodiment, the depression depth T0 of the first pit in the thickness direction of the film body ranges from 0.5 mm to 50 mm.
[0016] Beneficial effects: It can not only ensure that the first pit has sufficient depression depth to provide sufficient accommodation space for the electrode group in the thickness direction, avoid the mutual extrusion between the encapsulation film and the electrode group, and reduce the damage to the electrode group, but also avoid the excessive depression depth of the first pit resulting in the poor fitting of the first bottom surface with the surface of the electrode group, thereby ensuring the relative stability between the electrode group and the encapsulation film, and further improving the safety of the battery cell.
[0017] In an optional implementation manner, the tab body includes a body region and a transition region, and the transition region is connected to both sides in the width direction of the body region; in the width direction, from the side where the transition region is connected to the body region to the side far from the body region, the thickness of the transition region gradually decreases; the second pit has a second bottom surface and second side surfaces, and the second side surfaces are connected to both sides in the width direction of the second bottom surface, and the second side surfaces are inclined with respect to the second bottom surface.
[0018] Beneficial effects: By setting that in the width direction, the thickness of the part of the transition region far from the body region is less than the thickness of the part close to the body region, the transition region has a bevel transition. At the same time, by setting the second side surfaces corresponding to the transition region on the second pit to be inclined, the second side surfaces are in fit with the transition region, avoiding the right-angle steps at both edges of the film body in the width direction of the tab structure, thereby reducing the shear force on the film body, avoiding the breakage of the film body, and further ensuring the sealing performance after the encapsulation film is encapsulated and improving the safety of the battery cell.
[0019] In an optional implementation manner, along the thickness direction of the tab body, the surface of the first side of the body region is the first surface, the surface of the first side of the transition region is the second surface, and the included angle between the second surface and the first surface is an obtuse angle and the angle is y; the included angle between the second side surface and the second bottom surface is an obtuse angle and the angle is x; wherein, x and y satisfy the relationship: 0.9 ≤ x / y ≤ 1.2.
[0020] Beneficial effects: By setting x / y to take values between 0.9 and 1.2, the fitting degree between the second pit on the encapsulation film 1 and the tab structure can be ensured, thereby ensuring the sealing effect after encapsulation.
[0021] In an optional implementation manner, the value range of the included angle y between the second surface and the first surface is: 95° ≤ y ≤ 160°;
[0022] And / or, the value range of the included angle x between the second side surface and the second bottom surface is: 95° ≤ x ≤ 160°.
[0023] Beneficial effects: By setting the value of y to be between 95° and 160°, it is possible to reduce the excessive shear force on the edge of the film body at the tab structure after encapsulation, thereby avoiding the failure of the film body due to breakage, and ensuring a good degree of adhesion between the film body and the tab body, thereby ensuring good encapsulation adhesion, achieving a good sealing effect, and ensuring the structural strength of the tab body;
[0024] By setting the value of x to be between 95° and 160°, it is possible to avoid excessive shear force on the film body during the formation of the second pit, thereby avoiding the failure of the film body due to breakage, and ensuring a good degree of adhesion between the second side surface and the transition area on the tab body, thereby ensuring good encapsulation adhesion and achieving a good sealing effect.
[0025] In an optional embodiment, the first pit has a first bottom surface and a first side surface. The second bottom surface is connected to the first side surface and there is a rounded corner transition between the two. The radius of the circle where the rounded corner is located is R1, where 0.3 mm ≤ R1 ≤ 2 mm.
[0026] Beneficial effects: By providing a rounded corner transition connection between the first side surface of the first pit and the second bottom surface of the second pit, the stress concentration phenomenon at the connection between the two is reduced. At the same time, by limiting the radius R1 of the rounded corner to be between 0.3 mm and 2 mm, it is possible to avoid excessive stress generated during the punching and stretching of the film body, which may cause cracking and damage of the packaging film, and to avoid the generation of small air bubbles at the rounded corner transition position, thereby ensuring the safety of the battery cell.
[0027] In a second aspect, the present invention also provides a battery cell, including: the above-mentioned battery cell. Since the battery cell includes the battery cell and has the same effects as the battery cell, it will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] 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 following drawings 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.
[0029] Figure 1 It is a schematic structural diagram of a battery cell according to an embodiment of the present invention;
[0030] Figure 2 It is a schematic structural diagram of a packaging film according to an embodiment of the present invention;
[0031] Figure 3 For Figure 2 The top view of the shown packaging film;
[0032] Figure 4 is Figure 3 a sectional view taken along the A-A direction in
[0033] Figure 5 is Figure 4 a partially enlarged schematic view of the encapsulation film near the edge in
[0034] Figure 6 is Figure 3 a sectional view taken along the B-B direction in
[0035] Figure 7 is Figure 6 a partially enlarged schematic view of D in
[0036] Figure 8 is Figure 3 a partially enlarged schematic view of C in
[0037] Figure 9 is Figure 1 a sectional view taken along the E-E direction in
[0038] Figure 10 is Figure 9 a partially enlarged schematic view of F in
[0039] Figure 11 a structural schematic view of a tab structure according to an embodiment of the present invention;
[0040] Figure 12 is Figure 11 a top view of the tab structure shown in
[0041] Figure 13 is Figure 12 a sectional view taken along the N-N direction in
[0042] Figure 14 is Figure 13 a partially enlarged schematic view of P in
[0043] Figure 15 a cross-sectional schematic view of the encapsulation film of the embodiment of the present invention along its thickness direction.
[0044] Explanation of reference numerals:
[0045] 1. Encapsulation film; 101. Film body; 102. First pit; 1021. First bottom surface; 1022. First side surface; 103. Second pit; 1031. Second bottom surface; 1032. Second side surface; 104. Heat-sealed seal; 111. PP layer; 112. Protective layer; 2. Electrode group; 3. Tab structure; 301. Tab body; 3011. Body area; 3012. Transition area; 3013. First surface; 3014. Second surface; 302. Seal. Detailed implementation manners
[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0047] The encapsulation film of the battery cell is usually formed by buckling two film bodies up and down, and the edges of the encapsulation film are heat-sealed. There are no pits corresponding to the tabs on the traditional encapsulation film. During the encapsulation process of the encapsulation film, for the area without tabs at the sealing edge, the two film bodies are attached to each other, while for the area corresponding to the tabs, the film body needs to be attached to the surface of the tab. Since the tab structure has a certain thickness, the encapsulation edge of the encapsulation film has a stepped transition from the area corresponding to the tab structure to the area without tabs, which will stretch the position on the encapsulation film corresponding to the side of the tab. The stretching deformation causes damage to the encapsulation film structure. Therefore, during the long-term use of the battery cell, there is a high risk of plastic encapsulation failure caused by the rupture of the encapsulation film in the tab area.
[0048] The following combines Figures 1 to 15 , to describe the embodiments of the present invention.
[0049] According to an embodiment of the present invention, on the one hand, a battery cell is provided, including: an encapsulation film 1, an electrode assembly 2, and a tab structure 3. The encapsulation film 1 includes two buckled film bodies 101, and each film body 101 is provided with a first pit 102 and a second pit 103. The second pit 103 is connected to the side of the first pit 102, and the depression depth of the second pit 103 along the thickness direction of the film body 101 is T1; the electrode assembly 2 is arranged between the two film bodies 101, and the electrode assembly 2 is located in the first pit 102; one end of the tab structure 3 is connected to the side of the electrode assembly 2 and the other end extends out of the encapsulation film 1. A partial area of the tab structure 3 close to the electrode assembly 2 is located in the second pit 103, and the maximum dimension of the tab structure 3 along its thickness direction is t2, where 0.8 ≤ 2T1 / t2 ≤ 1.1. Here, the depression depth refers to the depression dimension along the thickness direction of the film body 101; the thickness direction of the film body 101 refers to Figures 4 to 5 the "thickness direction" indicated by the arrow in Figure 14 and the thickness direction of the tab structure 3 refers to the "thickness direction" indicated by the arrow in
[0050] When applying the battery cell of this embodiment, by providing the film body 101 of the encapsulation film 1 with a first pit 102 and a second pit 103 that are connected and communicate with each other, the film body 101 not only has a space for accommodating the electrode group 2, but also has a space for accommodating the tab structure 3. At the same time, by defining that the depression depth T1 of the second pit 103 and the maximum dimension t2 of the tab structure 3 along its thickness direction satisfy the relational expression of 0.8 ≤ 2T1 / t2 ≤ 1.1, the second pit 103 has a reasonable depression depth, which can avoid serious step stretching deformation at the position of the film body 101 corresponding to the edge of the tab structure 3 due to the inability of the second pit 103 to provide sufficient accommodation space for the tab structure 3 along the thickness direction, thereby avoiding excessive damage to the film body 101, and can also avoid wrinkles generated after hot pressing due to the excessive size of the second pit 103 along the thickness direction, thereby ensuring the sealing performance and reducing the risk of plastic sealing failure of the encapsulation film 1.
[0051] It should be noted that the number of the film bodies 101 is two, and the openings of the pits on the two film bodies 101 are arranged opposite to each other. The accommodation space is formed by the pits arranged opposite to each other between the two mutually buckled film bodies 101. Among them, the pits refer to the first pit 102 and the second pit 103 on each film body 101. 2T1 is the total dimension of the accommodation space for accommodating the tab structure 3 along the thickness direction of the battery cell. If 2T1 / t2 is less than 0.8, the dimension of the space for accommodating the tab structure 3 formed by the second pit 103 along the thickness direction is insufficient. During hot melt plastic sealing and hot pressing, the step stretching deformation at the positions of the film body 101 corresponding to the two side edges of the tab structure 3 along its width direction is serious, and the damage to the film body 101 is large, which will lead to sealing failure; if 2T1 / t2 is greater than 1.1, the dimension of the space for accommodating the tab structure 3 formed by the second pit 103 along the thickness direction is too large. During hot melt plastic sealing and hot pressing, wrinkles are generated at the sealing part formed by heat sealing, and there is also a large risk of sealing failure. Among them, the thickness direction of the battery cell refers to Figures 9 to 10 the "thickness direction" indicated by the arrow in Figure 1 which is the same as the thickness direction of the film body 101 and the thickness direction of the tab structure 3; the width direction refers to
[0052] Preferably, the encapsulation film 1 is an aluminum-plastic film. Further, as shown in Figure 15 , the aluminum-plastic film includes a PP layer 111 (Polypropylene) and a non-PP layer. Among them, the non-PP layer forms a protective layer 112. When 2T1 / t2 is greater than 1.1, wrinkles are generated at the sealing part formed by heat pressing the edge of the encapsulation film, resulting in insufficient adhesion between the PP layer and the non-PP layer and delamination, and further leading to the risk of sealing failure.
[0053] Preferably, the structures and sizes of the two film bodies 101 are the same and are symmetrically arranged. Each film body 101 has a first pit 102 and two second pits 103. Further preferably, pole tabs are provided at both ends of the pole group 2. Correspondingly, along the length direction of the film body 101, one second pit 103 is connected to each of the two sides of the first pit 102. The first pit 102 and the second pits 103 are formed by punching the film body 101. Among them, the length direction refers to Figures 2 to 5 the "length direction" indicated by the arrow in
[0054] In one embodiment, the value range of the maximum dimension t2 of the pole tab structure 3 along its thickness direction is: 0.2 mm ≤ t2 ≤ 20 mm. Among them, the thickness direction refers to Figures 13 to 14 the "thickness direction" indicated by the arrow in
[0055] When t2 is greater than 0.2 mm, a pit design needs to be carried out in the area of the film body 101 corresponding to the pole tab structure 3. If t2 is less than 0.2 mm, the maximum dimension of the pole tab structure 3 along its thickness direction is too small, and there is no need to design the second pit 103 on the film body 101. The too small thickness of the pole tab structure 3 will also cause excessive heat generation and too high temperature rise of the pole tab body 301 during the charge and discharge process of the battery cell, which has a certain danger; if t2 is greater than 20 mm, the maximum dimension of the pole tab structure 3 along its thickness direction is too large, which is not convenient for processing the matching second pit 103, and the weight of the pole tab structure 3 is too large, which is not conducive to improving the energy density of the battery cell.
[0056] In one embodiment, further combined with Figures 9 to 14 as shown, the pole tab structure 3 includes a pole tab body 301 and a seal 302. The seal 302 is attached to the surface of the pole tab body 301. The total thickness of the pole tab body 301 and the seal 302 is the maximum dimension of the pole tab structure 3 along its thickness direction. By attaching the seal 302 to the surface of the pole tab body 301, the insulation between the pole tab body 301 and the encapsulation film 1 is ensured, and it is convenient to thermally seal between the pole tab structure 3 and the encapsulation film 1 to ensure the sealing performance after encapsulation.
[0057] In one embodiment, the seal 302 is a pole tab glue to facilitate the thermal sealing between the pole tab structure and the encapsulation film 1 and further improve the sealing performance after thermal sealing.
[0058] Further combined with Figure 1As shown, the four sides of the encapsulation film 1 are heat-sealed by the heat-sealing seal 104, and the tab glue is located at a position corresponding to the heat-sealing seal 104. During the heat-sealing process, the tab glue melts and then solidifies, thereby increasing the sealing performance between the encapsulation film 1 and the tab structure 3.
[0059] In one embodiment, the depression depth T1 of the second pit 103 along the thickness direction of the film body 101 ranges from 0.2 mm to 10 mm. If T1 is less than 0.2 mm, the depression depth of the second pit 103 is too small, there is no need for punching, and the processing is difficult, and the punching is difficult to form; if T1 is greater than 10 mm, the size of the space for accommodating the tab structure 3 formed by the second pit 103 along the thickness direction is too large. During the hot-melt plastic sealing and hot pressing, wrinkles are generated at the heat-sealing seal, the sealing performance is poor, and it may also cause the film body 1 to delaminate and fail. Therefore, by setting the depression depth T1 of the second pit 103 to be within the range of 0.2 mm to 10 mm, unnecessary punching can be avoided, the processing difficulty can be reduced, sufficient accommodation space for the tab structure 3 can be provided along the thickness direction, and wrinkles generated after hot pressing can be avoided due to the too large size of the second pit 103 along the thickness direction, thereby ensuring the sealing performance and reducing the risk of plastic sealing failure of the encapsulation film 1.
[0060] In one embodiment, the depression depth of the first pit 102 along the thickness direction of the film body 101 is T0, where 0.1 ≤ T1 / T0 ≤ 0.6. T1 / T0 is the ratio of the depression depths of the second pit 103 and the first pit 102. If T1 / T0 is less than 0.1, the depression depth of the second pit 103 is too small relative to the depression depth of the first pit 102, there is no need for punching, and the processing is difficult, and the punching is difficult to form; further combined with Figure 8 As shown, the intersection of the first side surface 1022 of the first pit 102, the second bottom surface 1031 of the second pit 103, and the second side surface 1032 is rounded. If T1 / T0 is greater than 0.6, the depression depth of the second pit 103 is too large relative to the depression depth of the first pit 102, and the fillet surface M at the multi-surface intersection of the first side surface 1022, the second bottom surface 1031, and the second side surface 1032 is subjected to too large a tensile force, having a large risk of cracking and breakage.
[0061] Therefore, by setting the ratio T1 / T0 of the depression depth of the second pit 103 to the depression depth of the first pit 102 to be within the range of 0.1 to 0.6, the processing difficulty can be reduced, it can be ensured that the second pit 103 can provide sufficient accommodation space for the tab structure 3 along the thickness direction, heat-sealing failure can be avoided, and the fillet surface at the intersection of the first pit 102 and the second pit 103 can be prevented from being subjected to too large a tensile force, thereby avoiding cracking and breakage of the film body 101 and further ensuring the sealing performance after encapsulation.
[0062] In one embodiment, the depression depth T0 of the first pit 102 in the thickness direction of the film body 101 ranges from 0.5 mm to 50 mm. It should be noted that the first pit 102 is used to accommodate the body part of the electrode group 2. If T0 is less than 0.5 mm, the depression depth of the first pit 102 is too small to provide sufficient accommodation space for the electrode group 2 in the thickness direction. After the encapsulation film 1 is encapsulated, it will be squeezed against the electrode group 2 in the thickness direction, resulting in poor encapsulation effect and damage to the electrode group 2. If T0 is greater than 50 mm, the depression depth of the first pit 102 is too large, and the size of the accommodation space formed by the relative first pits 102 of the upper and lower film bodies 101 in the thickness direction is too large. The first bottom surface 1021 of the first pit 102 cannot fit well with the surface of the electrode group 2, and the relative stability between the electrode group 2 and the encapsulation film 1 is poor, and the safety performance is poor.
[0063] Therefore, by setting the depression depth T0 of the first pit 102 to be within the range of 0.5 mm to 50 mm, it can not only ensure that the first pit 102 has sufficient depression depth to provide sufficient accommodation space for the electrode group 2 in the thickness direction, avoid mutual extrusion between the encapsulation film 1 and the electrode group 2, and reduce damage to the electrode group 2, but also avoid the depression depth of the first pit 102 being too large, resulting in the first bottom surface 1021 not fitting well with the surface of the electrode group 2, thereby ensuring the relative stability between the electrode group 2 and the encapsulation film 1, and further improving the safety of the battery cell.
[0064] In one embodiment, further combined with Figure 10 As shown, the tab body 301 includes a body region 3011 and a transition region 3012. The transition region 3012 is connected to both sides of the body region 3011 in the width direction; in the width direction, from the side where the transition region 3012 is connected to the body region 3011 to the side away from the body region 3011, the thickness of the transition region 3012 gradually decreases; further combined with Figures 6 to 7 As shown, the second pit 103 has a second bottom surface 1031 and a second side surface 1032. The second side surface 1032 is connected to both sides of the second bottom surface 1031 in the width direction, and the second side surface 1032 is inclined with respect to the second bottom surface 1031. Among them, the width direction refers to Figures 6 to 7 and Figure 10 the "width direction" indicated by the arrow in Figure 1 and is the same as the width direction shown in Figure 7 ; the dividing line between the body region 3011 and the transition region 3012 is as shown by the dashed straight line in
[0065] It should be noted that on the cross-section parallel to the width direction, the surfaces on the upper and lower sides of the cross-section of the transition zone 3012 along the thickness direction are both inclined with respect to the surface of the main body zone 3011. By setting that in the width direction, the thickness of the part of the transition zone 3012 far from the main body zone 3011 is less than the thickness of the part close to the main body zone 3011, the transition zone 3012 is in a bevel transition. At the same time, the second side surface 1032 corresponding to the transition zone 3012 on the second recess 103 is inclined, so that the second side surface 1032 fits with the transition zone 3012, avoiding right-angle steps at the two side edges of the film body 101 in the width direction of the tab body 301, thereby reducing the shear force on the film body 101, avoiding damage to the film body 101, and further ensuring the sealing performance after the encapsulation film 1 is encapsulated and improving the safety of the battery cell.
[0066] In one embodiment, along the thickness direction of the tab body 301, the surface of the first side of the main body zone 3011 is the first surface 3013, and the surface of the first side of the transition zone 3012 is the second surface 3014. The included angle between the second surface 3014 and the first surface 3013 is an obtuse angle and the angle is y; the included angle between the second side surface 1032 and the second bottom surface 1031 is an obtuse angle and the angle is x; wherein, x and y satisfy the relationship: 0.9 ≤ x / y ≤ 1.2. It should be noted that along the thickness direction of the tab body 301, the tab body 301 has opposite two sides, and the first side of the main body zone 3011 and the first side of the transition zone 3012 are the same side of the tab body 301 along its thickness direction. If the value of x / y is too small or too large, the fitting degree between the second side surface 1032 of the second recess 103 on the film body 101 and the transition zone 3012 on the tab structure 3 will be poor, affecting the plastic sealing fit and the sealing effect after encapsulation will be poor.
[0067] Therefore, by setting the value of x / y to be between 0.9 and 1.2, the fitting degree between the second recess 103 on the encapsulation film 1 and the tab structure 3 can be ensured, thereby ensuring the sealing effect after encapsulation.
[0068] In one embodiment, the range of the angle y between the second surface 3014 and the first surface 3013 is: 95° ≤ y ≤ 160°. If y is less than 95°, the angle between the second surface 3014 and the first surface 3013 is too small, the slope of the transition region 3012 of the tab body 301 is too large, and the shearing force received at the position on the encapsulation film 1 corresponding to the transition region 3012 after encapsulation is too large, and the encapsulation film 1 is easily damaged; if y is greater than 160°, the dimension of the transition region 3012 in the width direction is too large, the structure is relatively weak, and the fitting effect with the second side surface 1032 of the second pit 103 is poor, and the sealing effect after plastic encapsulation is poor. Therefore, by setting y to take values between 95° and 160°, it is possible to reduce the excessive shearing force on the edge of the film body 1 after plastic encapsulation, thereby avoiding the failure of the film body 101 due to damage, and ensuring a good fitting degree between the film body 101 and the tab body 301, thereby ensuring plastic encapsulation fitting, achieving a good sealing effect, and ensuring the structural strength of the tab body 301.
[0069] In one embodiment, the range of the angle x between the second side surface 1032 and the second bottom surface 1031 is: 95° ≤ x ≤ 160°. If x is less than 95°, the angle between the second side surface 1032 and the second bottom surface 1031 is too small, and the film body 101 receives a large shearing force during the punching process, and the PP layer will be damaged and fail; if x is greater than 160°, the angle between the second side surface 1032 and the second bottom surface 1031 is too large, and the fitting degree with the stepped inclined surface of the transition region 3012 of the tab body 301 is poor, affecting plastic encapsulation fitting and resulting in a poor sealing effect. Therefore, by setting x to take values between 95° and 160°, it is possible to avoid the excessive shearing force on the film body 101 during the formation of the second pit 103, thereby avoiding the failure of the film body 101 due to damage, and ensuring a good fitting degree between the second side surface 1032 and the transition region 3012 on the tab body 301, thereby ensuring plastic encapsulation fitting and achieving a good sealing effect.
[0070] In one embodiment, the first pit 102 has a first bottom surface 1021 and a first side surface 1022, the second bottom surface 1031 is connected to the first side surface 1022 and there is a rounded corner transition between them, and the radius of the circle where the rounded corner is located is R1, where 0.3 mm ≤ R1 ≤ 2 mm. It should be noted that if R1 is less than 0.3 mm, the rounded corner is too small, and when the film body 101 is punched and stretched, the stress received at the connection between the second bottom surface 1031 of the second pit 103 and the first side surface 1022 of the first pit 102 is too large, and cracking and damage are likely to occur; if R1 is greater than 2 mm, the rounded corner is too large, the fitting degree at this position with the pole group 2 is poor, and after the battery cell is encapsulated, there will be uneven small bubbles, resulting in gas that cannot be discharged inside the battery cell, affecting the safety of the battery cell.
[0071] Therefore, by setting a rounded transition connection between the first side surface 1022 of the first pit 102 and the second bottom surface 1031 of the second pit 103, the stress concentration phenomenon at the connection of the two is reduced. At the same time, by limiting the radius R1 of the rounded corner to be between 0.3 mm and 2 mm, it is possible to avoid the encapsulation film 1 from cracking and breaking due to excessive stress generated during the pit punching and stretching of the film body 101, and it is also possible to avoid small air bubbles from generating at the rounded corner transition position, thereby ensuring the safety of the battery cell.
[0072] For different values of the relationship formula 2T1 / t2 between the depression depth T1 of the second pit 103 and the maximum dimension t2 of the tab structure 3 along its thickness direction, the encapsulation film 1 and the battery cell are processed correspondingly. The following describes the influence of different values of 2T1 / t2 on the battery cell.
[0073] Table 1 Influence of different values of 2T1 / t2 on the battery cell
[0074]
[0075] As can be seen from Table 1, for the battery cells of Embodiment 1 to Embodiment 4, the values of 2T1 / t2 are all within the range of 0.8 to 1.1, that is, within the range defined in this application, and neither the encapsulation film nor the battery cell fails; while for the battery cell of Comparative Case 1, 2T1 / t2 is 0.79, less than 0.8, not within the range defined in this application. During the hot melt sealing and hot pressing of the encapsulation film, the aluminum-plastic film steps on both sides in the width direction of the tab structure are severely stretched and deformed, resulting in sealing failure; for the battery cell of Comparative Case 2, 2T1 / t2 is 1.11, greater than 1.1, not within the range defined in this application. Wrinkles appear at the welded joints formed during hot pressing, and the adhesion between the PP layer and the non-PP layer of the aluminum-plastic film is insufficient, resulting in a risk of sealing failure.
[0076] In summary, when 2T1 / t2 takes values within the range of 0.8 to 1.1, it is possible to make the second pit 103 have a reasonable depression depth, which can not only avoid severe step stretching deformation at the positions on the film body 101 corresponding to the two side edges in the width direction of the tab structure 3, thereby avoiding excessive damage to the film body 101, but also avoid wrinkles generated after hot pressing due to the excessive size of the second pit 103 in the thickness direction, and avoid the risk of sealing failure due to insufficient adhesion between the PP layer and the non-PP layer of the aluminum-plastic film, thereby reducing the risk of sealing failure of the encapsulation film 1 and ensuring the sealing performance.
[0077] For different values of the ratio T1 / T0 between the depression depth of the second pit 103 and the depression depth of the first pit 102, the encapsulation film 1 and the battery cell are processed correspondingly. The following describes the influence of different values of T1 / T0 on the battery cell.
[0078] Table 2 Influence of different values of T1 / T0 on the battery cell
[0079]
[0080] As can be seen from Table 2, for the battery cells of Embodiment 5 to Embodiment 8, the value of T1 / T0 is within the range of 0.1 to 0.6, that is, within the range defined in the present application, and no failure occurs in the encapsulation film and the battery cell; while for the battery cell of Comparative Example 3, the value of T1 / T0 is 0.61, which is greater than 0.6 and not within the range defined in the present application. When punching, the fillet surface at the multi-surface junction is subjected to excessive tensile force and cracks; for the battery cell of Comparative Example 4, the value of T1 / T0 is 0.05, which is less than 0.1 and not within the range defined in the present application. The depression depth of the second pit is too small, the second pit is not obvious, and it is not easy to form.
[0081] In summary, when the ratio T1 / T0 of the depression depth of the second pit 103 to the depression depth of the first pit 102 is within the range of 0.1 to 0.6, it can not only reduce the processing difficulty, ensure that the second pit 103 can provide sufficient accommodation space for the tab structure 3 in the thickness direction, but also avoid excessive tensile force on the fillet surface at the junction of the first pit 102 and the second pit 103, thereby avoiding cracking and damage of the film body 101 and further ensuring the sealing performance after encapsulation.
[0082] According to an embodiment of the present invention, on the other hand, a battery pack is further provided, including: the above-mentioned battery cell. Preferably, the number of battery cells in the battery pack is multiple; the battery cell is a lithium-ion battery cell.
[0083] 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 fall within the scope defined by the appended claims.
Claims
1. A battery cell, characterized in that: include: The packaging film comprises two film bodies which are buckled with each other, each of the film bodies is provided with a first pit and a second pit, the second pit is connected to the side of the first pit, and the second pit has a concave depth T1 along the thickness direction of the film body; A pole group is arranged between the two membrane bodies, and the pole group is located in the first pit; A pole ear structure, one end of which is connected to the side of the pole group and the other end extends out of the packaging film, a partial area of the pole ear structure close to the pole group is located in the second pit, and the maximum dimension of the pole ear structure along its thickness direction is t2, wherein 0.8≤2T1 / t2≤1.
1.
2. The battery cell according to claim 1, characterized in that: The maximum dimension t2 of the tab structure along its thickness direction has a value range of: 0.2 mm ≤ t2 ≤ 20 mm; And / or, a value range of a depression depth T1 of the second pit along the thickness direction of the film body is: 0.2 mm ≤ T1 ≤ 10 mm.
3. The battery cell according to claim 1, characterized in that: The tab structure includes a tab body and a seal. The seal is attached to the surface of the tab body. The total thickness of the tab body and the seal is the maximum dimension of the tab structure along its thickness direction.
4. The battery cell according to any one of claims 1 to 3, characterized in that: The depression depth of the first pit along the thickness direction of the film body is T0, wherein 0.1≤T1 / T0≤0.
6.
5. The battery cell according to claim 4, characterized in that: The range of the depression depth T0 of the first pit along the thickness direction of the film body is: 0.5mm≤T0≤50mm.
6. The battery cell according to claim 3, characterized in that: The tab body comprises a main body region and a transition region, wherein the transition region is connected to both sides of the main body region in a width direction; in the width direction, the thickness of the transition region gradually decreases from the side where the transition region is connected to the main body region to the side away from the main body region; The second recess has a second bottom surface and a second side surface, the second side surface is connected to both sides of the second bottom surface in a width direction, and the second side surface is inclined relative to the second bottom surface.
7. The battery cell according to claim 6, characterized in that: Along the thickness direction of the tab body, the surface of the first side of the body region is the first surface, the surface of the first side of the transition region is the second surface, and the angle between the second surface and the first surface is an obtuse angle and the angle is y; The included angle between the second side surface and the second bottom surface is an obtuse angle and the angle is x; Among them, the relationship between x and y is: 0.9≤x / y≤1.
2.
8. The battery cell according to claim 7, characterized in that: The value range of the angle y between the second surface and the first surface is: 95°≤y≤160°; And / or, a value range of an included angle x between the second side surface and the second bottom surface is: 95°≤x≤160°.
9. The battery cell according to claim 6, characterized in that: The first pit has a first bottom surface and a first side surface, the second bottom surface is connected to the first side surface and there is a rounded transition between the two, and the radius of the circle where the rounded corner is located is R1, wherein 0.3mm≤R1≤2mm.
10. A battery pack, characterized in that: include: The battery cell according to any one of claims 1 to 9.