Secondary battery and electrical device
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-07-30
- Publication Date
- 2026-08-13
Smart Images
Figure CN2024108532_13082026_PF_FP_ABST
Abstract
Description
Secondary batteries and electrical devices Technical Field
[0001] This application relates to the field of battery technology, and in particular to a secondary battery and an electrical device. Background Technology
[0002] In related technologies, the top of a pouch battery is typically not folded, resulting in a large space occupied at the battery head. To improve this situation, a folded top seal design can be considered. Specifically, at least one tab's metal strip and tab adhesive will bend together with the top seal. However, the tab adhesive is quite hard and difficult to bend. Even after bending, the tab adhesive occupies a significant amount of space in the battery height direction, which is detrimental to increasing the secondary battery capacity.
[0003] Application content
[0004] The purpose of this application is to provide a secondary battery and an electrical device that aims to increase the capacity of the secondary battery.
[0005] According to a first aspect of this application, a secondary battery is provided, comprising a packaging bag, an electrode assembly, and a first tab. The packaging bag includes a main body, a first top seal, and a first side seal. The electrode assembly is disposed within the main body. The main body includes a first top wall and a first side wall, the first top seal being connected to the first top wall and bent in a first direction, the first side wall being located on one side of the first top wall along a second direction, and the first side seal being connected to the first side wall, wherein the first direction is perpendicular to the second direction. A first gap is formed between the first side seal and the first top seal along the second direction. The first tab includes a first metal strip and a first tab adhesive surrounding the first metal strip. One end of the first metal strip is electrically connected to the electrode assembly, the first tab adhesive is adhered to the packaging bag, and the other end of the first tab extends out of the packaging bag through the first tab adhesive and the first gap.
[0006] In the secondary battery of this application, the first tab no longer extends from the first top seal, thus the folding of the first top seal is not affected by the hardness of the first tab adhesive. Compared to the scheme where the first tab extends from the first top seal and both are bent together, the bending rebound force generated by folding the first top seal is smaller, that is, the warping degree of the first top seal is reduced, and the space occupied by the first top seal in the third direction after bending is reduced, which is beneficial to increasing the battery capacity of the secondary battery.
[0007] In one or more of the above / optional embodiments, the main body includes a second top wall. The second top wall connects the first top wall and the first side wall, and the second top wall is recessed in a third direction relative to the first top wall. The third direction, the second direction, and the first direction are perpendicular to each other. The packaging bag includes a second top seal. The second top seal is disposed on the second top wall and connects the first top seal and the first side seal. The other end of the first metal strip extends out of the packaging bag through the second top seal and the first gap.
[0008] In one or more of the above-described embodiments, the second top wall includes a first connecting wall and a second connecting wall. The second connecting wall is connected to the first top wall via the first connecting wall. Both the second connecting wall and the first top wall are arranged parallel to the first direction.
[0009] In one or more of the above / optional embodiments, the first tab adhesive is disposed on the second top seal portion. Along a third direction, one end of the first tab adhesive extends beyond one side edge of the second top seal portion. Viewed along the second direction, the projection of the portion of the first tab adhesive extending beyond one side edge of the second top seal portion coincides with the projection of the first top seal portion. The advantage of this arrangement is that, due to the height limitation of the first tab adhesive, a portion of the head space is wasted in the distance the first tab adhesive extends beyond the side edge of the packaging bag where it is sealed. By having the first top seal portion and the first tab adhesive overlap along a third direction, this wasted space can be better utilized, thereby increasing energy density. A portion of the distance is offset by the space occupied by the first top seal portion in the third direction, further reducing the head space occupied by the secondary battery, and thus further increasing the capacity of the secondary battery.
[0010] In one or more of the above / optional embodiments, the distance S1 between the second connecting wall and the surface of the first top seal portion away from the first top wall along the third direction is defined as follows: S2 is the sum of the distance between the end of the second top seal portion near the second connecting wall and the end away from the second connecting wall along the third direction, and the distance of the portion of the first tab adhesive extending beyond the edge of the second top seal portion. S1 and S2 satisfy: S1 ≥ S2. In this way, with minimal impact on the volumetric energy density of the secondary battery, the first tab adhesive does not need to be bent, thereby mitigating the leakage caused by insufficient connection strength around the first tab adhesive due to bending.
[0011] In one or more of the above / optional embodiments, the packaging bag includes a second side seal. The main body includes a second sidewall. The second sidewall is located on the opposite side of the first top wall along the second direction, and the second side seal is connected to the second sidewall. A second gap is formed between the second side seal and the first top seal along the first direction. The secondary battery includes a second tab. The second tab includes a second metal strip and a second tab adhesive surrounding and covering the second metal strip. One end of the first metal strip is electrically connected to the electrode assembly, and the other end of the second tab extends out of the packaging bag through the second tab adhesive and the second gap.
[0012] In one or more of the above / optional embodiments, the main body includes a third top wall. The third top wall connects to the first top wall and the second side wall, and is recessed in a third direction relative to the first top wall. The third direction, the second direction, and the first direction are perpendicular to each other. The packaging bag includes a third top seal. The third top seal is disposed on the third top wall and connects to the first top seal and the second side seal. The other end of the second metal strip extends out of the packaging bag through the third top seal and the second gap.
[0013] In the above technical solution, the second tab no longer extends from the second top seal. Therefore, when folding the second top seal, it is not affected by the hardness of the second tab adhesive. Compared with the solution where the second tab extends from the first top seal and both are bent together, the bending rebound force generated by folding the first top seal is smaller, that is, the warping degree of the first top seal is reduced. After the first top seal is bent, the space occupied in the third direction is reduced, thereby reducing the space occupied at the head of the secondary battery and thus increasing the capacity of the secondary battery.
[0014] In one or more of the above-described embodiments, the third top wall includes a third connecting wall and a fourth connecting wall. The fourth connecting wall is connected to the first top wall via the third connecting wall. Both the fourth connecting wall and the first top wall are arranged parallel to the first direction.
[0015] In one or more of the above / optional embodiments, the second tab adhesive is disposed on the third top seal portion. Along the third direction, one end of the second tab adhesive extends beyond one side edge of the third top seal portion. Viewed along the second direction, the projection of the portion of the second tab adhesive extending beyond one side edge of the third top seal portion coincides with the projection of the first top seal portion. With this configuration, a portion of the distance from the second tab adhesive extending beyond the side edge of the packaging bag where the second tab adhesive is sealed is offset by the space occupied by the first top seal portion in the third direction, thereby further reducing the space occupied at the head of the secondary battery and thus further increasing the capacity of the secondary battery.
[0016] In one or more of the above / optional embodiments, the packaging bag has a first cavity and a second cavity communicating with the first cavity.
[0017] The electrode assembly includes an electrode assembly body and a protrusion integrally connected to the electrode assembly body. The electrode assembly body is housed in a first cavity, and the protrusion is housed in a second cavity. One end of the first metal strip and one end of the second metal strip are both electrically connected to the electrode assembly body. The electrode assembly includes a first electrode, a second electrode, and a separating membrane separating the first electrode and the second electrode. The first electrode includes a first electrode body and a first protrusion integrally connected to the first electrode body. The second electrode includes a second electrode body and a second protrusion integrally connected to the second electrode body. The separating membrane includes a separating membrane body and a third protrusion integrally connected to the separating membrane body. The electrode assembly body is formed by alternatingly stacking the first electrode body, the separating membrane body, and the second electrode body. The protrusion is formed by alternatingly stacking the first protrusion, the third protrusion, and the second protrusion.
[0018] In one or more of the above-mentioned embodiments, along the third direction, the connection between the electrode assembly body and the first metal strip is disposed opposite to the second top wall. On the one hand, the shortened gap between the protrusion and the first top seal reduces the amount of free electrolyte accumulating in this area, thereby improving the situation where short circuits occur due to membrane shrinkage caused by excessive free electrolyte accumulating at this location impacting the separator membrane of the protrusion. On the other hand, the first top seal is no longer affected by the first metal strip and the first tab adhesive during heat sealing, and the first top seal has stable connection strength after heat sealing. Furthermore, the outward extension dimension of the first top seal is also reduced because it is no longer affected by the first metal strip and the first tab adhesive, thereby further improving the volumetric energy density of the secondary battery.
[0019] In one or more of the above-described embodiments, along the third direction, the connection between the electrode assembly body and the second metal strip is positioned opposite to the third top wall. Based on a mechanism similar to that described in the electrical connection between the first electrode body and the first tab, it also has similar effects to those in the aforementioned embodiments, and will not be detailed here. Furthermore, when the first tab and the second tab are located on opposite sides of the first top seal along the second direction, even though the presence of the first space and the second space reduces the capacity of the secondary battery, the increased capacity of the protrusion compared to a top-sealed battery of the same size is still greater than the sum of the reduced capacities of the two spaces, meaning the total capacity of the secondary battery can still be increased.
[0020] In one or more of the above / optional embodiments, the number of the third protrusions is at least two. Along the third direction, the ends of at least two of the third protrusions extending beyond the second protrusions are connected and fixed to each other to form a connecting portion. This configuration, where multiple third protrusions are connected and fixed to form an overall structure, can increase the upper limit of the maximum impact stress resistance, thereby mitigating the situation where the separator membrane folds and short-circuits when free electrolyte impacts the protrusions.
[0021] In one or more of the above / optional embodiments, the length of the connecting portion along the second direction is 15mm-120mm.
[0022] In one or more of the above-mentioned embodiments, the second side seal is bent toward the first direction.
[0023] In one or more of the above / optional embodiments, the first side seal is bent toward the first direction.
[0024] According to a second aspect of this application, an electrical device is provided, comprising a secondary battery as described above.
[0025] Additional aspects and advantages of the embodiments of this application will be described, shown, or illustrated in part by way of implementation of the embodiments of this application in the following description. Attached Figure Description
[0026] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.
[0027] Figure 1 is a schematic diagram of the structure of a secondary battery provided in the first embodiment of this application;
[0028] Figure 2 is a schematic diagram of another secondary battery provided in the first embodiment of this application;
[0029] Figure 3 is a magnified view of part a in Figure 1;
[0030] Figure 4 is a magnified view of part b in Figure 1;
[0031] Figure 5 is a schematic diagram of the structure of the secondary battery shown in Figure 1 when the electrode assembly is not assembled in the packaging bag;
[0032] Figure 6 is a magnified view of point c in the secondary battery shown in Figure 5;
[0033] Figure 7 is a schematic diagram of the structure of the secondary battery shown in Figure 1 from another angle;
[0034] Figure 8 is a magnified view of a portion d in Figure 7;
[0035] Figure 9 is a magnified view of part e in Figure 7;
[0036] Figure 10 is a cross-sectional view along line AA in Figure 1;
[0037] Figure 11 is a magnified view of a portion of point f in Figure 10;
[0038] Figure 12 is a schematic diagram of the structure of a secondary battery provided in the second embodiment of this application;
[0039] Figure 13 is a schematic diagram of another secondary battery provided in the second embodiment of this application;
[0040] Figure 14 is a schematic diagram of another structure of the secondary battery provided in the second embodiment of this application;
[0041] Figure 15 is a schematic diagram of the secondary battery structure provided in the second embodiment of this application;
[0042] Figure 16 is a partial cross-sectional view of point g in Figure 15;
[0043] Figure 17 is a partial cross-sectional view of point h in Figure 15;
[0044] Figure 18 is a cross-sectional view along line BB in Figure 15;
[0045] Figure 19 is a magnified view of a portion i in Figure 18;
[0046] Figure 20 is an exploded view of the secondary battery structure shown in Figure 12. Detailed Implementation
[0047] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.
[0048] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.
[0049] In the description of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0050] The term "perpendicular" is used to describe an ideal state between two components. In actual production or use, two components can exist in a state that is approximately perpendicular. For example, in numerical terms, perpendicularity can refer to the angle between two straight lines within the range of 90° ± 10°, the dihedral angle between two planes within the range of 90° ± 10°, or the angle between a straight line and a plane within the range of 90° ± 10°. The two components described as "perpendicular" do not have to be absolutely straight lines or planes; they can be approximately straight lines or planes. From a macroscopic perspective, if the overall direction of extension is straight or plane, the component can be considered a "straight line" or "plane".
[0051] The term "parallel" is used to describe an ideal state between two components. In actual production or use, two components can exist in a state that is approximately parallel. For example, in numerical terms, parallel can refer to the angle between two straight lines within the range of 180° ± 10°, the dihedral angle between two planes within the range of 180° ± 10°, or the angle between a straight line and a plane within the range of 180° ± 10°.
[0052] Two components described as "parallel" do not necessarily have to be perfectly straight lines or planes; they can be roughly straight or planes. As long as the overall direction of extension is straight or plane from a macroscopic perspective, the components can be considered "straight" or "plane." Due to manufacturing tolerances, a deviation of less than 0.5mm between two planes can be considered parallel.
[0053] The technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.
[0054] As shown in Figures 1 to 20, for ease of description, a three-dimensional rectangular coordinate system is established with the thickness direction of the secondary battery as the first direction X, the width direction of the secondary battery as the second direction Y, and the length direction of the secondary battery as the third direction Z.
[0055] In some embodiments, the first direction X is parallel to the direction in which the first main wall 111 and the second main wall 112 in the packaging bag 10, which will be described in detail below, are disposed opposite to each other; in addition, the first direction X is also parallel to the direction in which the electrodes in the electrode assembly 20, which will be described in detail below, are stacked.
[0056] In some embodiments, the second direction Y is parallel to the direction in which the first sidewall 1132 and the second sidewall 1134 of the packaging bag 10, which will be described in detail below, are disposed opposite to each other; in addition, the second direction Y is also parallel to the direction in which the first top seal portion 12 of the packaging bag 10, which will be described in detail below, extends from the side near the first side seal portion 13 to the side near the second side seal portion 16.
[0057] In some embodiments, the third-party direction Z is parallel to the direction in which the first top wall 1131 and bottom wall 1133 of the packaging bag 10 are disposed opposite to each other; in addition, the third-party direction Z is also parallel to the extension direction of the first tab 30, which is described in detail below.
[0058] First Embodiment
[0059] Figure 1 is a structural schematic diagram of a secondary battery provided in the first embodiment of this application, and Figure 5 is a structural schematic diagram of the secondary battery shown in Figure 1 when the electrode assembly is not assembled in the packaging bag.
[0060] First, referring to Figures 1 and 5, the secondary battery includes: a packaging bag 10, an electrode assembly 20, a first tab 30, and a second tab 40. The packaging bag 10 serves as the housing for the electrode assembly 20, defining a receiving cavity (not shown), within which the electrode assembly 20 is housed. The first tab 30 and the second tab 40 are both located on the same side of the packaging bag 10. Within the receiving cavity, one end of the first tab 30 and one end of the second tab 40 are electrically connected to the electrode assembly 20. The other ends of the first tab 30 and the second tab 40 extend out of the packaging bag 10 through the receiving cavity. The first tab 30 and the second tab 40 are configured to be electrically connected to an electrical device to enable charging and discharging of the secondary battery.
[0061] In some embodiments, the secondary battery includes an electrolyte that is contained within a housing cavity and wets the electrode assembly 20.
[0062] In some embodiments, the secondary battery is a pouch lithium-ion secondary battery.
[0063] Next, taking a pouch-type lithium-ion secondary battery as an example, we will explain its structure. It is understood that the secondary battery can also be other types of pouch-type secondary batteries besides lithium-ion secondary batteries. Examples of such pouch-type secondary batteries include pouch-type sodium-ion secondary batteries, solid-state pouch-type secondary batteries, and semi-solid-state pouch-type secondary batteries.
[0064] Figure 2 is a schematic diagram of another secondary battery provided in the first embodiment of this application. Figure 3 is a partial enlarged view of point a in Figure 1. Figure 4 is a partial enlarged view of point b in Figure 1. Figure 10 is a cross-sectional view along line AA in Figure 1.
[0065] The structure of the packaging bag 10 will now be described in conjunction with Figures 1 to 4, 5 and 8.
[0066] Referring to Figure 1 and Figure 10 together, in some embodiments, the packaging bag 10 is generally flat and rectangular, including a main body 11, a first top seal 12, a first side seal 13, and a second side seal 16. The main body 11 includes a first main wall 111, a second main wall 112, and multiple side walls 113. The multiple side walls 113 include a first top wall 1131, a first side wall 1132, a second side wall 1134, and a bottom wall 1133. The first top wall 1131, the first side wall 1132, the bottom wall 1133, and the second side wall 1134 are connected end to end and respectively connected to the periphery of the first main wall 111 and the periphery of the second main wall 112 to jointly enclose the aforementioned receiving cavity. The first main wall 111 and the second main wall 112 are arranged opposite each other, the first side wall 1132 and the second side wall 1134 are arranged opposite each other, and the bottom wall 1133 and the first top wall 1131 are arranged opposite each other. The first top sealing portion 12 is connected to the first top wall 1131 and bends in the first direction X. The first side sealing portion 13 is connected to the first side wall 1132 and extends outward. The second side sealing portion 16 is connected to the second side wall 1134 and extends outward.
[0067] It is understood that the shape of the packaging bag 10 is not limited to the aforementioned cuboid shape, and can be adapted to meet actual usage requirements. For example, in some other embodiments, the packaging bag 10 may be L-shaped or a regular polyhedral shape. In addition, the shape of the packaging bag 10 is related to the shape of the electrode assembly 20, which will be described in detail below, and its shape may change with the shape of the electrode assembly 20.
[0068] As can be seen from Figure 3, in some embodiments, a first gap 14 is formed between the first side seal 13 and the first top seal 12 along the second direction Y. The other end of the first tab 30 extends out of the packaging bag 10 through the receiving cavity and the first gap 14.
[0069] Specifically, along the second direction Y, a first gap 14 is formed between the edge of the first side seal 13 along the third direction Z and the edge of the first top seal 12 along the second direction Y.
[0070] The first tab 30 includes a first metal strip 31 and a first tab adhesive 32 surrounding and covering the first metal strip 31. The first tab adhesive 32 is disposed on the packaging bag 10, and along the third direction Z, the projection of the first tab adhesive 32 falls into the first gap 14. One end of the first metal strip 31 is electrically connected to the electrode assembly 20 within the receiving cavity, and along the third direction Z, the other end of the first metal strip 31 extends out of the packaging bag 10 through the first tab adhesive 32 and the first gap 14. The portion of the first metal strip 31 extending out of the packaging bag 10 can be electrically connected to an electrical device.
[0071] It should be noted that, when observed along the first direction X, if the projection of one edge of the first top seal 12 along the second direction Y is separate from the projection of one edge of the first side seal 13 along the third direction Z, it can be determined that a first gap 14 is formed between the first side seal 13 and the first top seal 12 along the second direction Y. Alternatively, when observed along the third direction Z, if the projection of one edge of the first top seal 12 along the second direction Y is separate from the projection of one edge of the first side seal 13 along the third direction Z, it can also be determined that a first gap 14 is formed between the first side seal 13 and the first top seal 12 along the second direction Y.
[0072] In the secondary battery of this application, the first tab 30 no longer extends from the first top seal 12, and therefore the hardness of the first tab adhesive 32 does not affect the folding of the first top seal 12. Compared with the scheme where the first tab 30 extends from the first top seal 12 and both are bent together, the bending rebound force generated by folding the first top seal 12 is smaller, that is, the warping degree of the first top seal 12 is reduced, and the space occupied by the first top seal 12 in the third direction Z is reduced after bending, which is beneficial to increasing the battery capacity of the secondary battery.
[0073] As can be seen from Figure 4, in some embodiments, a second gap 15 is formed between the second side seal 16 and the first top seal 12 along the second direction Y. The other end of the second tab 40 extends out of the packaging bag 10 through the receiving cavity and the second gap 15.
[0074] Specifically, along the second direction Y, a second gap 15 is formed between one edge of the second side seal 16 along the third direction Z and the other edge of the first top seal 12 along the second direction Y.
[0075] The second tab 40 includes a second metal strip 41 and a second tab adhesive 42 surrounding and covering the second metal strip 41. The second tab adhesive 42 is disposed in the packaging bag 10, and along the third direction Z, the projection of the second tab adhesive 42 falls into the second gap 15. One end of the second metal strip 41 is electrically connected to the electrode assembly 20 within the receiving cavity, and the other end of the second metal strip 41 extends out of the packaging bag 10 through the second tab adhesive 42 and the second gap 15. The portion of the second metal strip 41 extending out of the packaging bag 10 can be electrically connected to an electrical device.
[0076] It should be noted that the determination condition of the second gap 15 can be determined that a second gap 15 is formed between the second side seal 16 and the first top seal 12 along the second direction Y. Since the determination condition of the second gap 15 is similar to the determination condition of the first gap 14, the details can be referred to the relevant description in the first gap 14, and will not be repeated here.
[0077] In the above technical solution, the second tab 40 no longer extends from the second top seal 17. Therefore, when folding the second top seal 17, it is not affected by the hardness of the second tab adhesive 42. Compared with the solution where the second tab 40 extends from the first top seal 12 and both are bent together, the bending rebound force generated by folding the first top seal 12 is smaller, that is, the warping degree of the first top seal 12 is reduced. After the first top seal 12 is bent, the space occupied in the third direction Z is reduced, thereby reducing the space occupied at the head of the secondary battery and thus increasing the capacity of the secondary battery.
[0078] Of course, the arrangement of the first tab 30 and the second tab 40 can be adapted to meet actual usage requirements. For example, as shown in Figure 2, in some embodiments, the first tab 30 and the second tab 40 are located on opposite sides of the packaging bag 10. The first tab 30 extends from the first gap 14 located at the head of the secondary battery, and the second tab 40 extends from the second gap 15 located at the tail of the secondary battery. This reduces the space occupied at both the head and tail of the secondary battery, and also helps to increase the capacity of the secondary battery.
[0079] The packaging bag 10 includes a first film 101 and a second film 102. The first film 101 and the second film 102 can be integrally formed or separate. For example, as shown in Figure 5, the first film 101 and the second film 102 can be formed by folding a single film material with a composite layer structure. In specific implementations…
[0080] First, a first notch 1011 is punched out at the first corner of the first diaphragm 101, and a second notch 1021 is punched out at the position corresponding to the first notch 1011 at the first corner of the second diaphragm 102; a third notch 1012 is punched out at the second corner of the first diaphragm 101, and a fourth notch 1022 is punched out at the position corresponding to the third notch 1012 at the second corner of the second diaphragm 102.
[0081] Secondly, at least one of the first diaphragm 101 and the second diaphragm 102 is formed with at least one pit after a denting process;
[0082] Then, the electrode assembly 20 is folded over and wrapped along the fold line in the middle of the diaphragm;
[0083] Then, seal all the edges except for the part where the dent is located, and hot press the first corner to melt and form the first tab adhesive 32, the first diaphragm 101, and the second diaphragm 102. Then hot press the second corner to melt and form the second tab adhesive 42, the first diaphragm 101, and the second diaphragm 102.
[0084] Among them, the two sealing edges adjacent to the first gap 1011 are the aforementioned first top sealing part 12 and first side sealing part 13, and the sealing edge that is disposed opposite to the first side sealing part 13 along the second direction Y is the second side sealing part 16.
[0085] The aforementioned receiving cavity is a closed space formed by stamping and stretching at least one of the first diaphragm 101 and the second diaphragm 102 and then encapsulating it.
[0086] The first top sealing part 12 bends in the first direction X, and is used to partially fit against the first top wall 1131.
[0087] The first top seal 12 defines the boundary of the first gap 14 by one edge along the second direction Y and the first side seal 13 defining the boundary of the first gap 14 by one edge along the third direction Z.
[0088] The first top seal 12 defines the boundary of the second gap 15 by its other edge along the second direction Y and the second side seal 16 defining one edge along the third direction Z.
[0089] In some embodiments, the composite layer structure includes a first polymer layer, a metal layer, and a second polymer layer, which are sequentially stacked from inside the cavity to outside the cavity to form the aforementioned first membrane 101 and / or second membrane 102.
[0090] The first polymer layer melts at a preset temperature and has adhesive properties to facilitate sealing with the packaging bag 10. Materials used to make this first polymer layer include polyethylene, polypropylene, polycarbonate, polyamide, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer, polyoxymethylene, and polyphenylene ether. This makes the first polymer layer difficult to dissolve or swell with the electrolyte, thereby reducing the risk of corrosion of the metal layer adjacent to the first polymer layer.
[0091] The metal layer is used to reduce the risk of moisture seeping into the containment cavity and to improve the structural strength of the packaging bag 10. Examples of materials for making such a metal layer include aluminum foil and austenitic-ferritic duplex stainless steel foil. The metal layer can react with oxygen in the air to form a dense oxide film, thereby reducing the risk of moisture seeping into the containment cavity.
[0092] The second polymer layer is used to reduce the risk of air infiltration into the containment cavity, while also improving the deformability of the packaging bag 10. Examples of materials that can be used to make such a second polymer layer include polyamide, polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer, polyoxymethylene, and polyphenylene ether.
[0093] It is understood that the encapsulation method between the first diaphragm 101 and the second diaphragm 102 is not specifically limited in the embodiments of this application. For example, the first diaphragm 101 and the second diaphragm 102 can be fixedly connected by adhesive bonding or hot pressing, or they can be pressed together first and then heat-sealed, or other processes can be used to achieve the fixed connection between the first diaphragm 101 and the second diaphragm 102.
[0094] It is also understandable that the structure of the packaging bag 10 is diverse and not limited to the specific structure of the packaging bag 10 mentioned above. It only needs to serve as a receiving substrate for the electrode assembly 20 and have a similar deformation capability as the packaging bag 10 described above. In addition, the packaging bag 10 should be configured such that a first gap 14 is formed between the edge of the first top seal portion 12 along the second direction Y and the edge of the bent first side seal portion 13 along the third direction Z, and the first gap 14 allows the other end of the first electrode tab 30 to extend out.
[0095] In some embodiments, the first side seal 13 and / or the second side seal 16 are bent toward the first direction X. The first side seal 13 is used to fit against the first sidewall 1132, and the second side seal 16 is used to fit against the second sidewall 1134. This reduces the space occupied by the secondary battery inside the electrical device, which can be used to increase the size of the electrode assembly 20, thereby improving the energy density of the secondary battery. In this case, the boundary of the first gap 14 can be defined by the edge of the bent first top seal 12 along the second direction Y and the edge of the bent first side seal 13 along the third direction Z.
[0096] Please refer to Figure 10 in conjunction with Figure 3 or Figure 9. In order to improve the situation where the first metal strip 31 contacts the exposed metal layer on the packaging bag 10 arranged around its outer periphery and short-circuits, in some embodiments, along the third direction Z, one end of the first tab adhesive 32 extends beyond the edge of the packaging bag 10 on which the first tab adhesive 32 is sealed.
[0097] Furthermore, observing along the second direction Y, the projection of the first tab adhesive 32 extending beyond the first top wall 1131 along the third direction Z overlaps with the projection of the first top seal 12. The advantage of this arrangement is that, due to the height limitation of the first tab adhesive 32, a portion of the head space is wasted in the distance beyond the edge of the packaging bag 10 where it is sealed. By ensuring that the first top seal 12 and the first tab adhesive 32 overlap along the third direction Z, this wasted space can be better utilized, thereby increasing energy density. A portion of the distance is offset by the space occupied by the first top seal 12 in the third direction Z, further reducing the head space occupied by the secondary battery and thus further increasing the capacity of the secondary battery.
[0098] Please refer to Figure 4 or Figure 8 in conjunction with Figure 10. Similarly, in order to improve the situation where the second metal strip 41 contacts the exposed metal layer on the packaging bag 10 arranged around its outer periphery and short-circuits, in some embodiments, along the third direction Z, one end of the second tab adhesive 42 extends beyond the edge of the packaging bag 10 on the side where the second tab adhesive 42 is sealed.
[0099] Furthermore, when viewed along the second direction Y, the projection of the portion of the second tab adhesive 42 extending beyond the packaging bag 10 along the third direction Z coincides with the projection of the second top seal 17. With this configuration, a portion of the distance from the edge of the second tab adhesive 42 extending beyond the packaging bag 10 where it is sealed is offset by the space occupied by the first top seal 12 in the third direction Z, thereby further reducing the space occupied by the secondary battery head and thus further increasing the capacity of the secondary battery.
[0100] Figure 6 is a magnified view of point c in the secondary battery shown in Figure 5.
[0101] Please refer to Figures 5 and 6 together. In some embodiments, the electrode assembly 20 includes a first electrode 21, a second electrode 22 with a polarity opposite to that of the first electrode 21, and a separating membrane 23 that separates the first electrode 21 and the second electrode 22. One of the first electrode 21 and the second electrode 22 is electrically connected to a first tab 30, and the other is electrically connected to a second tab 40.
[0102] For ease of description, in the following embodiments, the first electrode 21 is used as the positive electrode and the second electrode 22 is used as the negative electrode.
[0103] The first electrode 21 includes a first current collector (not shown) and a first active material layer (not shown) coated on at least one surface of the first current collector. The first current collector is electrically connected to one end of the first electrode tab 30 within the receiving cavity.
[0104] It is understood that the embodiments of this application do not specifically limit the electrical connection method between the first tab 30 and the first current collector. For example, in some embodiments, the first tab 30 and the first current collector are different parts of the same component. In specific implementation, the first tab 30 and the first current collector adapted to the shape of the main body 11 can be die-cut from a complete metal foil, and then a first active material layer can be coated on at least one surface of the first current collector to form the first electrode 21. For example, in other embodiments, the first tab 30 and the first current collector are independent components. In specific implementation, a groove exposing the surface of the first current collector can be scraped out on the first current collector coated with the first active material layer, and then the first tab 30 can be fixed to the surface of the first current collector in the groove by, but not limited to, laser welding.
[0105] The first current collector includes, but is not limited to, one or more conductive metal sheets such as aluminum mesh, aluminum foil, and copper foil. As an example, the first current collector is made of aluminum foil.
[0106] The first active material layer includes, but is not limited to, one or more of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium nickel oxide, lithium manganese iron phosphate, lithium vanadium phosphate, lithium iron phosphate, and lithium-rich manganese-based materials.
[0107] The second electrode 22 includes a second current collector and a second active material layer (not shown) coated on at least one surface of the second current collector (not shown). The second current collector is electrically connected to the second electrode tab 40 at one end that extends into the receiving cavity.
[0108] The second current collector includes, but is not limited to, one or two of conductive metal sheets such as copper foil and nickel foil. As an example, the second current collector is made of copper foil.
[0109] The second active material layer includes, but is not limited to, one or more of artificial graphite, natural graphite, soft carbon, hard carbon, graphene, mesophase carbon microspheres, silicon-based materials, tin-based materials, lithium carbonate, or other metals that can form alloys with lithium.
[0110] It is understood that the embodiments of this application do not specifically limit the electrical connection method between the second tab 40 and the second current collector. Since the connection method between the second tab 40 and the second current collector is similar to the connection method between the first tab 30 and the first current collector, please refer to the description of the possible connection methods between the first tab 30 and the first current collector, and will not be repeated here.
[0111] As shown in Figures 5 and 6, in some embodiments, the electrode assembly 20 may be a stacked structure. Specifically, the number of first electrode plates 21 is at least two, and the number of second electrode plates 22 is also at least two. At least two first electrode plates 21 and at least two second electrode plates 22 are stacked alternately along the first direction X, and the separator 23 separates the first electrode plates 21 and the second electrode plates 22.
[0112] In some embodiments, along the third direction Z, the electrical connection points of the plurality of first electrodes 21 and the first tab 30 and the first gap 14 are arranged opposite to each other.
[0113] In some embodiments, along the third direction Z, the electrical connection points of the plurality of second pole pieces 22 and the second pole piece 40 and the second gap 15 are arranged opposite to each other.
[0114] Alternatively, the electrode assembly 20 can be a wound structure. Specifically, there is one first electrode 21 and one second electrode 22, and both the first electrode 21 and the second electrode 22 are strip-shaped structures. The first electrode 21, the separator 23, and the second electrode 22 are stacked in sequence and wound more than two turns.
[0115] Of course, the electrode assembly 20 can also be other components besides the stacked structure or the wound structure, as long as it can realize the secondary battery charging and discharging function.
[0116] Second Embodiment
[0117] For ease of description, the same reference numerals are used throughout this application to identify elements with the same names. Based on the description of the first embodiment described above, but differing from it, as shown in FIG12 or FIG13, in some embodiments, the packaging bag 10 has a first space S1, which is connected to a first gap (not shown).
[0118] Specifically, the main body 11 includes a second top wall 1135, which includes a first connecting wall 11351 and a second connecting wall 11352. The second connecting wall 11352 and the first top wall 1131 are both located on the same side of the main body 11. The second connecting wall 11352 is connected to the first top wall 1131 via the first connecting wall 11351 and is recessed relative to the first top wall 1131 in a direction opposite to the third direction Z. The first connecting wall 11351 and the second connecting wall 11352 enclose the aforementioned first space S1 communicating with the first gap 14. It should be noted that as long as there is an uneven area in the third direction Z of the second top wall 1135, it can be considered that the second top wall 1135 is recessed relative to the first top wall 1131 in the third direction Z. This allows the connection point between the first tab 30 and the electrode assembly 20 to be closer to the center of the packaging bag 10, reducing the space occupied by the first tab 30.
[0119] The first tab adhesive 32 is disposed on the second connecting wall 11352 and extends beyond the second connecting wall 11352 to the first space S1 at one end along the third direction Z.
[0120] Along the third direction Z, the other end of the first metal strip 31 passes through the receiving cavity, the first tab adhesive 32, the first space S1 and the first gap and extends out of the packaging bag 10.
[0121] In the secondary battery involved in this application, the distance of the first tab adhesive 32 extending beyond the second connecting wall 11352 can be accommodated in the first space S1, or the distance of the first tab adhesive 32 extending beyond the second connecting wall 11352 can be accommodated in the space jointly enclosed by the first space S1 and the first top seal 12, thereby further reducing the space occupied by the head of the secondary battery, and thus further increasing the capacity of the secondary battery.
[0122] In some embodiments, the second connecting wall 11352 and the first top wall 1131 are both arranged parallel to the first direction X, which facilitates the subsequent sealing of the packaging bag 10 and the first tab 30.
[0123] In some embodiments, a rounded corner is provided at the connection between the first top wall 1131 and the first connecting wall 11351 to make the first top wall 1131 and the first connecting wall 11351 transition smoothly.
[0124] In some embodiments, a rounded corner is provided at the connection between the first connecting wall 11351 and the second connecting wall 11352 to make the first connecting wall 11351 and the second connecting wall 11352 smoothly transition.
[0125] In some embodiments, a rounded corner is provided at the connection between the second connecting wall 11352 and the first side wall 1132 to make the second connecting wall 11352 and the first side wall 1132 smoothly transition.
[0126] It is understood that the specific shape of the first space S1 is not limited in the embodiments of this application. For example, as shown in Figure 12 or Figure 13, in some embodiments, when viewed along the first direction X, the cross-sectional shape of the first space S1 is generally rectangular. In other embodiments, when viewed along the first direction X, the second top wall 1135 is generally inclined, with one end connected to the first top wall 1131 and the other end connected to the first side wall 1132. In this case, the first space S1 enclosed by the first top wall 1131, the second top wall 1135, and the first side wall 1132 may be triangular or other shapes.
[0127] Continuing with Figure 12, in some embodiments, the packaging bag 10 has a second space S2, which communicates with a second gap (not shown). Specifically, the third top wall 1136 includes a third connecting wall 11361 and a fourth connecting wall 11362. The fourth connecting wall 11362 and the first top wall 1131 are both located on the same side of the main body 11. The fourth connecting wall 11362 is connected to the first top wall 1131 through the third connecting wall 11361 and is recessed in a third direction Z relative to the first top wall 1131. The third connecting wall 11361 and the fourth connecting wall 11362 enclose the aforementioned second space S2 that communicates with the second gap. It should be noted that as long as there is an uneven area in the third direction Z of the third top wall 1136, it can be considered that the second top wall 1136 is recessed in the third direction Z relative to the first top wall 1131, which can bring the connection between the second electrode tab 42 and the electrode assembly 20 closer to the center of the packaging bag 10 and reduce the space occupied by the second electrode tab 42.
[0128] The second tab adhesive 42 is disposed on the fourth connecting wall 11362 and extends beyond the fourth connecting wall 11362 to the second space S2 at one end along the third direction Z.
[0129] Along the third direction Z, the other end of the second metal strip 41 passes through the second tab 42, the second space S2 and the second gap 15 in sequence and extends out of the packaging bag 10.
[0130] The advantage of this technical solution is that the distance of the second tab adhesive 42 beyond the fourth connecting wall 11362 can be accommodated in the second space S2, or the distance of the second tab adhesive 42 beyond the fourth connecting wall 11362 can be accommodated in the space jointly enclosed by the second space S2 and the first top seal 12. The space occupied in the third direction Z is offset by each other, thereby further reducing the space occupied by the secondary battery head, and thus further increasing the capacity of the secondary battery.
[0131] In some embodiments, the fourth connecting wall 11362 and the first top wall 1131 are both arranged parallel to the first direction X, which facilitates the subsequent encapsulation of the bag and the second tab.
[0132] In some embodiments, a rounded corner is provided at the connection between the first top wall 1131 and the third connecting wall 11361 to make the first top wall 1131 and the third connecting wall 11361 transition smoothly.
[0133] In some embodiments, the connection between the third connecting wall 11361 and the fourth connecting wall 11362 is provided with rounded corners to make the third connecting wall 11361 and the fourth connecting wall 11362 smoothly transition.
[0134] In some embodiments, a rounded corner is provided at the connection between the fourth connecting wall 11362 and the second side wall 1134 to make the fourth connecting wall 11362 and the second side wall 1134 smoothly transition.
[0135] It is understood that the specific shape of the second space S2 is not limited in the embodiments of this application. For example, as shown in FIG12, in some embodiments, when viewed along the first direction X, the cross-sectional shape of the second space S2 is generally rectangular. As another example, in some embodiments, when viewed along the first direction X, the third top wall 1136 is generally inclined, with one end connected to the first top wall 1131 and the other end connected to the second side wall 1134. In this case, the second space S2 enclosed by the first top wall 1131, the third top wall 1136, and the second side wall 1134 may be triangular or other shapes.
[0136] Third Embodiment
[0137] For ease of description, the same reference numerals are used throughout this application to identify elements with the same name. The description is based on the foregoing first embodiment, but differs from it in that...
[0138] As shown in Figures 14, 15, or 20, in some embodiments, the packaging bag 10 has a first groove 191 that communicates with a first gap (not shown).
[0139] Specifically, the second top wall 1135 includes a first connecting wall 11351 and a second connecting wall 11352. The second connecting wall 11352 and the first top wall 1131 are both located on the same side of the main body 11. The second connecting wall 11352 is connected to the first top wall 1131 through the first connecting wall 11351 and is recessed in a third direction Z relative to the first top wall 1131.
[0140] The packaging bag 10 includes a second top sealing part 17, which is connected to the second connecting wall 11352 and extends outward. The second top sealing part 17 is connected to the first top sealing part 12 and the first side sealing part 13 respectively. The first connecting wall 1135, the second top sealing part 17, and the second connecting wall 11352 together form the aforementioned first groove 191.
[0141] The first tab adhesive 32 is disposed on the second top seal portion 17 and the first tab adhesive 32 extends beyond one side edge of the second top seal portion 17 along the third direction Z to the first gap.
[0142] Along the third direction Z, the other end of the first metal strip 31 passes through the receiving cavity, the first tab adhesive 32 and the first gap and extends out of the packaging bag 10.
[0143] In the secondary battery of this application, the presence of the second top seal 17 allows for a larger contact area between the first tab adhesive 32 and the packaging bag 10, ensuring a stable and reliable connection between the first tab adhesive 32 and the second seal, thus reducing the possibility of leakage between the first metal strip 31 and the second top seal 17. The first groove 191 is located at one corner of the main body 11, facilitating the fixation and positioning of the first tab 30 by the hot-pressing fixture, thereby improving the assembly efficiency of the secondary battery.
[0144] It is understood that the specific shape of the first groove 191 is not limited in the embodiments of this application. For example, as shown in Figures 14-16 or Figure 20, in some embodiments, when viewed along the first direction X, the cross-sectional shape of the first groove 191 is generally rectangular. As another example, in some embodiments, the second top wall 1135 is inclined and connects the first top wall 1131 and the first side wall 1132 respectively. The first groove 191 is formed by the second top wall 1135, the second top sealing part 17, and the first side wall 1132. In this case, the first groove 191 may be a trapezoidal groove or other shapes.
[0145] In some embodiments, the second connecting wall 11352 and the first top wall 1131 are both arranged parallel to the first direction X, which facilitates the subsequent encapsulation of the bag body and the first tab.
[0146] As shown in Figure 14, in some embodiments, the distance S1 between the second connecting wall 11351 and the folded first top seal 12 along the third direction Z, and the sum S2 of the distance the second top seal 17 extends beyond the second connecting wall 11351 and the distance the first tab adhesive 32 extends beyond the second top seal 17, satisfy S1 ≥ S2. In this way, with minimal impact on the volumetric energy density of the secondary battery, the first tab adhesive 32 does not need to be bent, thereby mitigating the leakage caused by insufficient connection strength around the first tab adhesive 32 due to bending.
[0147] As shown in Figures 14-16 or 20, in some embodiments, the edge of the second top seal 17 away from the second connecting wall 1136 is flush with the edge of the first side seal 13 along the third direction Z. This reduces the processing steps of the packaging bag 10 and improves the production efficiency of the secondary battery. It should be noted that the "flush" mentioned here is not a strict flush; due to process tolerances, anything within 0.5mm should be considered flush.
[0148] As shown in Figures 14, 15, 17 or 20, in some embodiments, the packaging bag 10 has a second groove 192 that communicates with a second gap (not shown).
[0149] Specifically, the third top wall 1136 includes a third connecting wall 11361 and a fourth connecting wall 11362. The fourth connecting wall 11362 and the first top wall 1131 are both located on the same side of the main body 11. The fourth connecting wall 11362 is connected to the first top wall 1131 through the third connecting wall 11361 and is recessed relative to the first top wall 1131 in a direction opposite to the third direction Z.
[0150] The packaging bag 10 includes a third top seal 18, which is connected to a fourth connecting wall 11362 and extends out of the receiving cavity. The third top seal 18 is connected to a first top seal 12 and a second side seal 16. The third connecting wall 11361, the third top seal 18, and the fourth connecting wall 11362 together form the aforementioned second groove 192.
[0151] The second tab adhesive 42 is disposed on the third top seal 18 and extends beyond one side edge of the third top seal 18 to the second gap 15 at one end in the third direction Z.
[0152] Along the third direction Z, the other end of the second metal strip 41 passes through the receiving cavity, the second tab adhesive 42 and the second gap 15 in sequence and extends out of the packaging bag 10.
[0153] In the secondary battery of this application, the presence of the third top seal 18 allows for a larger contact area between the second tab adhesive 42 and the packaging bag 10, ensuring a stable and reliable connection between the second tab adhesive 42 and the third top seal 18, thus reducing the possibility of leakage between the second metal strip 41 and the third top seal 18. The second groove 192 is located at another corner of the main body 11, facilitating the fixation and positioning of the second tab 40 by the hot-pressing fixture, thereby improving the assembly efficiency of the secondary battery.
[0154] It is understood that the specific shape of the second groove 192 is not limited in the embodiments of this application. For example, as shown in Figures 11, 12, or 14, in some embodiments, when viewed along the first direction X, the cross-sectional shape of the second groove 192 is generally rectangular. In other embodiments, the third top wall 1135 connects the first top wall 1131 and the second side wall 1134 respectively, and the second groove 192 is formed by the third top wall 1135, the third top sealing portion 18, and the second side wall 1134. In this case, the first groove 192 may be a trapezoidal groove or other shapes.
[0155] In some embodiments, the fourth connecting wall 11362 and the first top wall 1131 are both arranged parallel to the first direction X, which facilitates the subsequent encapsulation of the bag and the second tab.
[0156] As shown in Figure 14, in some embodiments, the distance S3 between the fourth connecting wall 11362 along the third direction Z to the folded first top seal 12, and the sum of the distance S4 of the third top seal 18 extending beyond the fourth connecting wall 11362 and the distance beyond the edge of the third top seal 18 along the third direction Z side of the second tab adhesive 42, satisfy S3 ≥ S4. In this way, with minimal impact on the volumetric energy density of the secondary battery, the second tab adhesive 42 does not need to be bent, thereby improving the situation where insufficient connection strength around the second tab adhesive 42 leads to leakage due to bending of the second tab adhesive 42.
[0157] As shown in Figure 14 or Figure 20, in some embodiments, the edge of the third top seal 18 away from the fourth connecting wall 11362 is flush with the edge of the second side seal 16 along the third direction Z. The flushing is not strictly in the sense of being flush. Due to process tolerance, it should be considered flush within 0.5mm. This can reduce the processing steps of the packaging bag 10 and improve the production efficiency of secondary batteries.
[0158] Please refer to Figures 18-20. In some embodiments, the receiving cavity includes a first cavity (not shown) and a second cavity (not shown) communicating with the first cavity. The first cavity may be enclosed by a second connecting wall 11352, a first side wall 1132, a bottom wall 1133, a second side wall 1134, a fourth connecting wall 11362, and a virtual line connecting the fourth connecting wall 11362 and the second connecting wall 11352. The second cavity may be enclosed by a first top wall 1131, a first connecting wall 1135, a virtual line connecting the fourth connecting wall 11362 and the second connecting wall 11352, and a third connecting wall 11361.
[0159] The electrode assembly 20 includes an electrode assembly body 201 and a protrusion 202 integrally connected to the electrode assembly body 201. The electrode assembly 20 is housed in a first cavity, and the protrusion 202 is housed in a second cavity. Specifically, each first electrode 21 includes a first electrode body (not shown) and a first protrusion (not shown) integrally connected to the first electrode body; each second electrode 22 includes a second electrode body (not shown) and a second protrusion (not shown) integrally connected to the second electrode body; and each separator 23 includes a separator body (not shown) and a third protrusion (not shown) integrally connected to the separator body. The electrode assembly body 201 may be formed by alternatingly stacking at least two first electrode bodies, at least two separator bodies, and at least two second electrode bodies along a first direction X. The protrusion 202 may be formed by alternatingly stacking at least a first protrusion, at least a third protrusion, and at least two second protrusions along a first direction X.
[0160] It should be noted that the difference between the first electrode body and the first protrusion lies in their positions; the rest of their structures are largely the same. Both the first electrode body and the first protrusion include a first current collector and a first active material layer. Similarly, the difference between the second electrode body and the second protrusion lies in their positions; the rest of their structures are largely the same. Both the second electrode body and the second protrusion include a second current collector and a second active material layer. The difference between the separator body and the third protrusion lies in their positions; the rest of their structures are largely the same.
[0161] Within the first cavity, the electrode assembly body 201 is electrically connected to one end of the first electrode tab 30 and one end of the second electrode tab 40, respectively. Specifically, multiple first electrode bodies are electrically connected to one end of the first electrode tab 30, and multiple second electrode bodies are electrically connected to one end of the second electrode tab 40.
[0162] As shown in Figure 12, in some embodiments, along the third direction Z, the electrical connection points of multiple first electrode bodies and the first tab 30 and the second connecting wall 11352 are arranged opposite each other. In other words, the electrical connection points of multiple first electrode bodies and the first tab 30 are no longer arranged in the part of the second cavity opposite to the first top seal 12. On the one hand, the gap between the protrusion 202 and the first top seal 12 is shortened, which reduces the amount of free electrolyte accumulation in this part of the region, thereby improving the situation where the separator shrinks and short-circuits due to excessive free electrolyte accumulation impacting the separator 23 of the protrusion 202. On the other hand, the first top seal 12 is no longer affected by the first metal strip 31 and the first tab adhesive 32 during heat sealing, and the first top seal 12 has a stable connection strength after heat sealing. Furthermore, the outward extension dimension of the first top seal 12 is also reduced because it is no longer affected by the first metal strip 31 and the first tab adhesive 32, thereby further improving the volumetric energy density of the secondary battery.
[0163] Continuing with Figure 17, in some embodiments, along the third direction Z, multiple second electrode bodies are arranged opposite to the electrical connection points of the second tab 40 and the fourth connecting wall 11362. Based on a similar mechanism to that described above regarding the electrical connection between the first electrode body and the first tab 30, it also has similar effects to those in the aforementioned embodiments, and will not be described in detail here. Furthermore, when the first tab 30 and the second tab 40 are located on opposite sides of the first top seal portion 12 along the second direction Y, even though the presence of the first space S1 and the second space S2 reduces the capacity of the secondary battery, the increased capacity of the protrusion 202 compared to a top-sealed battery of the same size is still greater than the sum of the reduced capacities of the two spaces, meaning the total capacity of the secondary battery can still be increased. It should be noted that "multiple" here specifically refers to two or more.
[0164] As shown in Figure 19, in some embodiments, along a third direction, the ends of multiple third protrusions extending beyond the second protrusions are connected and fixed to each other to form a connecting portion (not shown), which can be fixed by hot pressing. With this configuration, the overall structure formed by the connection and fixation of multiple third protrusions can increase the upper limit of the maximum impact stress resistance, thereby mitigating the situation where the separator membrane 23 folds and short-circuits when the free electrolyte impacts the protrusion 202.
[0165] In traditional battery cells, since both the positive and negative tabs extend from the center of the electrode assembly, the connection portion cannot be made longer in the second direction Y due to interference from the tabs, resulting in a higher failure rate at the connection portion and causing the separator to shrink. The inventors of this application, through experimental demonstration, have limited the length of the connection portion in the second direction Y to 15mm-120mm. This type of secondary battery exhibits a superior failure rate in drop tests.
[0166] Furthermore, the length of the connecting part along the second direction is 20mm-120mm, thereby further increasing the connection strength of the connecting part.
[0167] As shown in Figures 12-15, in some embodiments, the first top seal 12 extends beyond the first top wall 1131 along one side edge of the second direction Y. This allows the first top seal 12 to maintain a safe distance from the first connecting wall 1135 at the connection point, ensuring a reliable seal and reducing the risk of leakage due to breakage at that location.
[0168] Similarly, the other edge of the first top sealing part 12 extends beyond the first top wall 1131 along the second direction Y.
[0169] Another embodiment of this application provides an electrical device including any of the rechargeable batteries described above. The electrical device of this application may be, but is not limited to, laptops, pen-based computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and lithium-ion capacitors, etc.
[0170] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.
Claims
1. A secondary battery, comprising a packaging bag, an electrode assembly, and a first tab, wherein the packaging bag comprises a main body, a first top seal, and a first side seal, the electrode assembly is disposed within the main body, the main body comprises a first top wall and a first side wall, the first top seal is connected to the first top wall and bent in a first direction, the first side wall is located on one side of the first top wall along a second direction, and the first side seal is connected to the first side wall, wherein... The first direction is perpendicular to the second direction, characterized in that, Along the second direction, a first gap is formed between the first side seal and the first top seal; The first tab includes a first metal strip and a first tab adhesive surrounding the first metal strip. One end of the first metal strip is electrically connected to the electrode assembly, and the first tab adhesive is bonded to the packaging bag. The other end of the first tab extends out of the packaging bag through the first tab adhesive and the first gap.
2. The secondary battery according to claim 1, characterized in that, The main body includes a second top wall, which is connected to the first top wall and the first side wall respectively, and the second top wall is recessed in a third direction relative to the first top wall, wherein the third direction, the second direction and the first direction are perpendicular to each other; The packaging bag includes a second top seal, which is disposed on the second top wall and connects the first top seal and the first side seal. The other end of the first metal strip extends out of the packaging bag through the second top seal and the first gap.
3. The secondary battery according to claim 2, characterized in that, The second top wall includes a first connecting wall and a second connecting wall, wherein the second connecting wall is connected to the first top wall through the first connecting wall; Both the second connecting wall and the first top wall are arranged parallel to the first direction.
4. The secondary battery according to claim 3, characterized in that, The first tab adhesive is disposed on the second top seal portion, and along the third direction, one end of the first tab adhesive extends beyond one side edge of the second top seal portion; When viewed along the second direction, the projection of the portion of the first tab that extends beyond the edge of the second top seal overlaps with the projection of the first top seal.
5. The secondary battery according to claim 4, characterized in that, The distance S1 between the second connecting wall and the surface of the first top seal portion away from the first top wall along the third direction, and the sum S2 of the distance between the end of the second top seal portion near the second connecting wall and the end away from the second connecting wall along the third direction and the distance of the first tab adhesive portion extending beyond the edge of the second top seal portion, S1 and S2 satisfy: S1≥S2.
6. The secondary battery according to any one of claims 2-5, characterized in that, The packaging bag includes a second side seal, the main body includes a second side wall, the second side wall is located on the other side of the first top wall along the second direction, and the second side seal is connected to the second side wall; Along the first direction, a second gap is formed between the second side seal and the first top seal; The secondary battery includes a second tab, which includes a second metal strip and a second tab adhesive surrounding and covering the second metal strip. One end of the first metal strip is electrically connected to the electrode assembly, and the other end of the second tab extends out of the packaging bag through the second tab adhesive and the second gap.
7. The secondary battery according to claim 6, characterized in that, The main body includes a third top wall, which is connected to the first top wall and the second side wall respectively, and the third top wall is recessed in a third direction relative to the first top wall, wherein the third direction, the second direction and the first direction are perpendicular to each other; The packaging bag includes a third top seal, which is disposed on the third top wall and connects the first top seal and the second side seal. The other end of the second metal strip extends out of the packaging bag through the third top seal and the second gap.
8. The secondary battery according to claim 7, characterized in that, The third top wall includes a third connecting wall and a fourth connecting wall, and the fourth connecting wall is connected to the first top wall through the third connecting wall; Both the fourth connecting wall and the first top wall are arranged parallel to the first direction.
9. The secondary battery according to claim 8, characterized in that, The second electrode tab adhesive is disposed on the third top seal portion, and one end of the second electrode tab adhesive extends beyond one side edge of the third top seal portion along the third direction; When viewed along the second direction, the projection of the portion of the second tab that extends beyond the edge of the third top seal overlaps with the projection of the first top seal.
10. The secondary battery according to claim 9, characterized in that, The packaging bag has a first cavity and a second cavity communicating with the first cavity; The electrode assembly includes an electrode assembly body and a protrusion integrally connected to the electrode assembly body. The electrode assembly body is housed in the first cavity, and the protrusion is housed in the second cavity. One end of the first metal strip and one end of the second metal strip are both electrically connected to the electrode assembly body; The electrode assembly includes a first electrode, a second electrode, and a separating membrane that separates the first electrode and the second electrode. The first electrode includes a first electrode body and a first protrusion integrally connected to the first electrode body; The second electrode includes a second electrode body and a second protrusion integrally connected to the second electrode body; The isolation membrane includes an isolation membrane body and a third protrusion integrally connected to the isolation membrane body; The electrode assembly body is formed by alternatingly stacking the first electrode body, the separator body, and the second electrode body, and the protrusion is formed by alternatingly stacking the first protrusion, the third protrusion, and the second protrusion.
11. The secondary battery according to claim 10, characterized in that, Along the third direction, the connection point between the electrode assembly body and the first metal strip is disposed opposite to the second top wall; and / or Along the third direction, the connection between the electrode assembly body and the second metal strip is positioned opposite to the third top wall.
12. The secondary battery according to claim 10, characterized in that, The number of the third protrusion is at least two, along... Along the third direction, at least two of the ends of the third protrusions that extend beyond the second protrusions are connected and fixed to each other to form a connecting portion.
13. The secondary battery according to claim 12, characterized in that, The length of the connecting part along the second direction is 15mm-120mm.
14. The secondary battery according to any one of claims 9-13, characterized in that, The second side seal is bent toward the first direction; and / or The first side seal is bent in the first direction.
15. An electrical appliance, characterized in that, Includes the secondary battery as described in any one of claims 1-14.