Secondary battery and electrical device

Abstract

The present application discloses a secondary battery and an electrical device. The secondary battery comprises a packaging bag, an electrode assembly and a first tab; the packaging bag comprises a main body portion, a first top sealing portion and a first side sealing portion; the main body portion comprises a first top wall and a first side wall; the first top sealing portion is connected to the first top wall and is bent in a first direction; the first side wall is located on one side of the first top wall in a second direction; the first side sealing portion is connected to the first side wall; in the second direction, a first gap is formed between the first side sealing portion and the first top sealing portion; the first tab comprises 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 penetrates through the first tab adhesive and the first gap to extend out of the packaging bag. By means of the arrangements, the capacity of the secondary battery provided in the present application can be improved.

Description

Secondary battery and electrical device Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a secondary battery and an electrical device. Background Art

[0002] In the prior art, soft-pack batteries typically do not have a folding top seal, which results in a large space occupied by the battery head. To improve this situation, a folding top seal design can be considered. Specifically, the metal strip and tab glue of at least one tab will bend along with the top seal. However, the tab glue is relatively hard and difficult to bend. Even after the tab glue is bent, it occupies a large space in the battery height direction, which is not conducive to increasing the capacity of the secondary battery.

[0003] Application Contents

[0004] The purpose of this application is to provide a secondary battery and an electrical device, aiming to increase the capacity of the secondary battery.

[0005] According to a first aspect of the present application, a secondary battery is provided, which includes 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 arranged in the main body. The main body includes 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. 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 glue arranged around the first metal strip. One end of the first metal strip is electrically connected to the electrode assembly, the first tab glue is adhered to the packaging bag, and the other end of the first tab extends out of the packaging bag through the first tab glue and the first gap.

[0006] In the secondary battery disclosed herein, the first tab no longer extends from the first top seal, and thus, the folding of the first tab is unaffected by the hardness of the first tab glue. Compared to a solution in which the first tab extends from the first top seal and both are bent together, the bending rebound force generated by the folding of the first top seal is smaller, i.e., the degree of warping of the first top seal is reduced. After the first top seal is bent, the space occupied in the third direction is reduced, which is beneficial for increasing the battery capacity of the secondary battery.

[0007] In one or more / optional embodiments above, the main body includes a second top wall. The second top wall connects the first top wall and the first side wall, respectively, and is recessed relative to the first top wall in a third direction. 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 provided on the second top wall and connects the first top seal and the first side seal. The other end of the first metal strap extends through the second top seal and the first gap, extending out of the packaging bag.

[0008] In one or more / optional embodiments above, 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. The second connecting wall and the first top wall are both arranged parallel to the first direction.

[0009] In the above one or more / optional embodiments, the first pole ear glue is arranged on the second top seal portion. Along the third direction, one end of the first pole ear glue exceeds the side edge of the second top seal portion. Observed along the second direction, the projection of the first pole ear glue exceeding the side edge of the second top seal portion overlaps with the projection of the first top seal portion. The advantage of this arrangement is that, in the distance where the first pole ear glue exceeds the side edge of the packaging bag where the first pole ear glue is encapsulated, a part of the head space is wasted due to the height limitation of the first pole ear glue. The first top seal portion and the first pole ear glue are arranged to overlap along the third direction, which can better utilize this part of the wasted space, thereby improving the energy density. A part of the distance is offset by the space size occupied by the first top seal portion in the third direction, thereby further reducing the space occupied by the head of the secondary battery, and then the capacity of the secondary battery can be further improved.

[0010] In one or more / optional embodiments above, the distance S1 between the second connecting wall and the surface of the first top seal portion facing away from the first top wall along the third direction. Along the third direction, the sum of the distance between the second top seal portion close to one end of the second connecting wall and one end away from the second connecting wall and the distance between the first pole ear glue and the edge portion of one side of the second top seal portion is S2. S1 and S2 satisfy: S1 ≥ S2. In this way, under the premise of having little impact on the volume energy density of the secondary battery, the first pole ear glue does not need to be bent, thereby improving the situation where the connection strength around the first pole ear glue is insufficient and leakage occurs due to bending the first pole ear glue.

[0011] In one or more / optional embodiments above, the packaging bag includes a second side seal portion. The main body portion 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 portion is connected to the second side wall. Along the first direction, a second gap is formed between the second side seal portion and the first top seal portion. The secondary battery includes a second tab. The second tab includes a second metal strip and a second tab glue wrapped around 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 glue and the second gap.

[0012] In one or more / optional embodiments above, the main body includes a third top wall. The third top wall connects the first top wall and the second side wall, respectively, and is recessed relative to the first top wall in a third direction. 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 provided on the third top wall and connects the first top seal and the second side seal. The other end of the second metal band extends through the third top seal and the second gap, extending out of the packaging bag.

[0013] In the above technical solution, the second pole ear no longer extends from the second top seal portion, and thus is not affected by the hardness of the second pole ear glue when the second top seal portion is folded. Compared with the solution in which the second pole ear extends from the first top seal portion and the two are bent together, the bending rebound force generated by the folding of the first top seal portion is smaller, that is, the warping degree of the first top seal portion is reduced, and the space occupied by the first top seal portion in the third direction after being bent is reduced, thereby reducing the space occupied by the head of the secondary battery, thereby increasing the capacity of the secondary battery.

[0014] In one or more / optional embodiments above, 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. The fourth connecting wall and the first top wall are both arranged parallel to the first direction.

[0015] In one or more / optional embodiments above, the second pole ear glue is provided on the third top seal portion. Along the third direction, one end of the second pole ear glue exceeds one side edge of the third top seal portion. Observed along the second direction, the projection of the second pole ear glue exceeding the one side edge of the third top seal portion overlaps with the projection of the first top seal portion. With such an arrangement, a portion of the distance that the second pole ear glue exceeds the one side edge of the packaging bag where the second pole ear glue is encapsulated is offset by the space occupied by the first top seal portion in the third direction, thereby further reducing the space occupied by the head of the secondary battery, and further increasing the capacity of the secondary battery.

[0016] In one or more / optional embodiments above, 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 accommodated in the first cavity, and the protrusion is accommodated 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 plate, a second electrode plate, and an isolation membrane separating the first electrode plate and the second electrode plate. The first electrode plate includes a first electrode plate body and a first protrusion integrally connected to the first electrode plate body. The second electrode plate includes a second electrode plate body and a second protrusion integrally connected to the second electrode plate 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 alternating the first electrode plate body, the isolation membrane body, and the second electrode plate body. The protrusion is formed by alternating the first protrusion, the third protrusion, and the second protrusion.

[0018] In one or more / optional embodiments above, along the third direction, the connection between the electrode assembly main body and the first metal strip is arranged opposite to the second top wall. On the one hand, the gap between the protrusion and the first top seal portion is shortened, which can reduce the amount of free electrolyte accumulated in this area, thereby improving the situation where the diaphragm shrinks and shorts due to the excessive free electrolyte accumulation impacting the isolation membrane of the protrusion. On the other hand, the first top seal portion is no longer affected by the first metal strip and the first ear glue during heat sealing, and the first top seal portion has a stable connection strength after heat sealing. On the other hand, the outward extension size of the first top seal portion is also reduced because it is not affected by the first metal strip and the first ear glue, thereby further improving the volume energy density of the secondary battery.

[0019] In one or more / optional embodiments above, along the third direction, the connection between the electrode assembly body and the second metal strip is arranged 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 as in the aforementioned embodiment, which will not be described in detail here. In addition, when the first tab and the second tab are respectively located on opposite sides of the first top seal along the second direction, even if the presence of the first space and the second space reduces the capacity of the secondary battery, compared to a folding top seal battery of the same size, the capacity increased by the convex portion is still greater than the sum of the capacity reductions of the aforementioned two, that is, the total capacity of the secondary battery can still be improved.

[0020] In one or more / optional embodiments described above, 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 protrusion are interconnected and fixed to form a connecting portion. This arrangement, resulting in a structure formed by the interconnection of multiple third protrusions, can increase the upper limit of the maximum impact stress resistance, thereby reducing the risk of the separator folding and shorting when free electrolyte impacts the separator on the protrusion.

[0021] In one or more / optional embodiments above, the length of the connecting portion along the second direction is 15 mm-120 mm.

[0022] In one or more / optional embodiments above, the second side seal portion is bent toward the first direction.

[0023] In one or more / optional embodiments above, the first side seal portion is bent toward the first direction.

[0024] According to a second aspect of the present application, there is provided an electrical device comprising the secondary battery described above.

[0025] Additional aspects and advantages of the embodiments of the present application will be described, shown, or explained in part in the following description through implementation of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To more clearly illustrate the specific embodiments of this application or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0027] FIG1 is a schematic structural diagram of a secondary battery provided in the first embodiment of the present application;

[0028] FIG2 is a schematic structural diagram of another secondary battery provided in the first embodiment of the present application;

[0029] FIG3 is a partial enlarged view of point a in FIG1 ;

[0030] FIG4 is a partial enlarged view of point b in FIG1 ;

[0031] FIG5 is a schematic structural diagram of the electrode assembly of the secondary battery shown in FIG1 when not assembled in a packaging bag;

[0032] FIG6 is a partial enlarged view of a portion c of the secondary battery shown in FIG5 ;

[0033] FIG7 is a schematic structural diagram of the secondary battery shown in FIG1 at another angle;

[0034] FIG8 is a partial enlarged view of point d in FIG7;

[0035] FIG9 is a partial enlarged view of point e in FIG7 ;

[0036] FIG10 is a cross-sectional view along line AA in FIG1 ;

[0037] FIG11 is a partial enlarged view of point f in FIG10 ;

[0038] FIG12 is a schematic structural diagram of a secondary battery provided in a second embodiment of the present application;

[0039] FIG13 is a schematic structural diagram of another secondary battery provided in the second embodiment of the present application;

[0040] FIG14 is another structural schematic diagram of a secondary battery provided in the second embodiment of the present application;

[0041] FIG15 is a schematic diagram showing another structure of a secondary battery provided in the second embodiment of the present application;

[0042] FIG16 is a partial cross-sectional view of point g in FIG15;

[0043] FIG17 is a partial cross-sectional view at point h in FIG15 ;

[0044] FIG18 is a cross-sectional view along line BB in FIG15 ;

[0045] FIG19 is a partial enlarged view of point i in FIG18;

[0046] FIG. 20 is an exploded view of the secondary battery structure shown in FIG. 12 . DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0048] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0049] In the description of this application, it should be noted that, unless otherwise specified or limited, the terms "mounted" and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0050] The term "perpendicular" is used to describe the ideal state between two components. In actual production or use, there may be a state that is approximately perpendicular between the two components. For example, combined with numerical descriptions, perpendicular can refer to the angle between two straight lines being in the range of 90°±10°, perpendicular can also refer to the dihedral angle between two planes being in the range of 90°±10°, and perpendicular can also refer to the angle between a straight line and a plane being in the range of 90°±10°. The two components described as "perpendicular" may not be absolute straight lines or planes, but may be roughly straight lines or planes. From a macroscopic perspective, a component can be considered a "straight line" or a "plane" if the overall extension direction is a straight line or a plane.

[0051] The term "parallel" is used to describe an ideal relationship between two components. In actual production or use, two components may be approximately parallel. For example, in conjunction with numerical descriptions, parallel can refer to the angle between two lines being within 180°±10°, the dihedral angle between two planes being within 180°±10°, or the angle between a line and a plane being within 180°±10°.

[0052] Two components described as "parallel" don't necessarily need to be perfectly straight or flat; they can be roughly straight or flat. From a macroscopic perspective, a component is considered "straight" or "flat" if its overall extension is straight or flat. Due to manufacturing tolerances, two planes within 0.5mm of each other are considered parallel.

[0053] The technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0054] As shown in FIG. 1 to FIG. 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 are relatively arranged, which will be described in detail below. In addition, the first direction X is also parallel to the direction in which the electrodes in the electrode assembly 20 are stacked, which will be described in detail below.

[0056] In some embodiments, the second direction Y is parallel to the direction in which the first side wall 1132 and the second side wall 1134 are relatively arranged in the packaging bag 10 to be described below; in addition, the second direction Y is also parallel to the direction from the side of the first top seal portion 12 close to the first side seal portion 13 to the side close to the second side seal portion 16 in the packaging bag 10 to be described below.

[0057] In some embodiments, the third direction Z is parallel to the relative direction of the first top wall 1131 and the bottom wall 1133 in the packaging bag 10 to be described below; in addition, the third direction Z is also parallel to the extension direction of the first electrode tab 30 to be described below.

[0058] First embodiment

[0059] FIG1 is a schematic structural diagram of a secondary battery provided in a first embodiment of the present application, and FIG5 is a schematic structural diagram of the secondary battery shown in FIG1 when the electrode assembly is not assembled in a packaging bag.

[0060] First, please refer to Figures 1 and 5 together. The secondary battery includes: a packaging bag 10, an electrode assembly 20, a first pole tab 30, and a second pole tab 40. Among them, the packaging bag 10 is a housing base for the electrode assembly 20, which defines a housing cavity (not shown), and the electrode assembly 20 is accommodated in the housing cavity. The first pole tab 30 and the second pole tab 40 are both located on the same side of the packaging bag 10. In the housing cavity, one end of the first pole tab 30 and one end of the second pole tab 40 are both electrically connected to the electrode assembly 20. The other end of the first pole tab 30 and the other end of the second pole tab 40 both extend through the housing cavity and extend out of the packaging bag 10. The first pole tab 30 and the second pole tab 40 are configured to be electrically connected to an electrical device to realize charging and discharging of the secondary battery.

[0061] In some embodiments, the secondary battery includes an electrolyte, which is contained in the receiving cavity and infiltrates the electrode assembly 20 .

[0062] In some embodiments, the secondary battery is a soft-pack lithium-ion secondary battery.

[0063] Next, the structure of a soft-pack lithium-ion secondary battery will be described using a soft-pack lithium-ion secondary battery as an example. It is understood that the secondary battery may also be other types of soft-pack secondary batteries besides soft-pack lithium-ion secondary batteries. Examples of such soft-pack secondary batteries include soft-pack sodium-ion secondary batteries, solid-state soft-pack secondary batteries, and semi-solid-state soft-pack secondary batteries.

[0064] FIG2 is a schematic structural diagram of another secondary battery provided in the first embodiment of the present application, FIG3 is a partial enlarged view of point a in FIG1 , FIG4 is a partial enlarged view of point b in FIG1 , and FIG10 is a cross-sectional view along line AA in FIG1 .

[0065] Next, the structure of the packaging bag 10 will be described with reference to FIG. 1 to FIG. 4 , FIG. 5 and FIG. 8 .

[0066] Referring to FIG10 in conjunction with FIG10 , in some embodiments, the packaging bag 10 is generally flat and rectangular in shape, and includes 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 a plurality of side walls 113. The plurality of 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 sequentially connected end to end and are respectively connected to the periphery of the first main wall 111 and the periphery of the second main wall 112 to collectively enclose the aforementioned receiving cavity. The first main wall 111 and the second main wall 112 are disposed opposite each other, the first side wall 1132 and the second side wall 1134 are disposed opposite each other, and the bottom wall 1133 and the first top wall 1131 are disposed opposite each other. The first top seal portion 12 is connected to the first top wall 1131 and is bent in the first direction X. The first side seal portion 13 is connected to the first side wall 1132 and extends outward. The second side seal 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 rectangular parallelepiped and can be adapted to actual usage requirements. For example, in other embodiments, the packaging bag 10 can be L-shaped or a regular polyhedron. Furthermore, 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 can vary accordingly.

[0068] 3 , in some embodiments, a first gap 14 is formed between the first side seal portion 13 and the first top seal portion 12 along the second direction Y. The other end of the first tab 30 passes through the accommodating cavity and the first gap 14 and extends out of the packaging bag 10 .

[0069] Specifically, along the second direction Y, a first gap 14 is formed between a side edge of the first side seal portion 13 along the third direction Z and a side edge of the first top seal portion 12 along the second direction Y.

[0070] The first electrode tab 30 includes a first metal strip 31 and a first electrode tab adhesive 32 wrapped around the first metal strip 31. The first electrode tab adhesive 32 is disposed within the packaging bag 10, and along the third direction Z, the projection of the first electrode tab adhesive 32 falls within the first gap 14. One end of the first metal strip 31 is electrically connected to the electrode assembly 20 within the accommodating cavity. Along the third direction Z, the other end of the first metal strip 31 extends out of the packaging bag 10 through the first electrode tab adhesive 32 and the first gap 14. The portion of the first metal strip 31 extending outside the packaging bag 10 can be electrically connected to an electrical device.

[0071] It should be noted that when, as viewed along the first direction X, the projection of one side edge of the first top seal portion 12 along the second direction Y is separated from the projection of one side edge of the first side seal portion 13 along the third direction Z, it can be determined that a first gap 14 is formed between the first side seal portion 13 and the first top seal portion 12 along the second direction Y. Alternatively, when, as viewed along the third direction Z, the projection of one side edge of the first top seal portion 12 along the second direction Y is separated from the projection of one side edge of the first side seal portion 13 along the third direction Z, it can also be determined that a first gap 14 is formed between the first side seal portion 13 and the first top seal portion 12 along the second direction Y.

[0072] In the secondary battery disclosed herein, the first tab 30 no longer extends from the first top seal 12. Therefore, when the first top seal 12 is folded, it is not affected by the hardness of the first tab glue 32. Compared to a solution in which the first tab 30 extends from the first top seal 12 and the two are bent together, the bending rebound force generated by the folding of the first top seal 12 is smaller, that is, the degree of warping 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, which is beneficial for increasing the battery capacity of the secondary battery.

[0073] 4 , in some embodiments, a second gap 15 is formed between the second side seal portion 16 and the first top seal portion 12 along the second direction Y. The other end of the second tab 40 extends out of the packaging bag 10 through the accommodating cavity and the second gap 15 .

[0074] Specifically, along the second direction Y, a second gap 15 is formed between one side edge of the second side seal portion 16 along the third direction Z and the other side edge of the first top seal portion 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 wrapping around the second metal strip 41. The second tab adhesive 42 is disposed within the packaging bag 10, and along the third direction Z, the projection of the second tab adhesive 42 falls within the second gap 15. One end of the second metal strip 41 is electrically connected to the electrode assembly 20 within the accommodating cavity, while 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 outside the packaging bag 10 can be electrically connected to an electrical device.

[0076] It should be noted that satisfying the determination conditions of the second gap 15 can determine that a second gap 15 is formed between the second side seal portion 16 and the first top seal portion 12 along the second direction Y. Since the determination conditions of the second gap 15 are similar to those of the first gap 14, the details can be referred to the relevant description of the first gap 14 and will not be repeated here.

[0077] In the above technical solution, the second pole tab 40 no longer extends from the second top seal portion 17, and thus is not affected by the hardness of the second pole tab glue 42 when the second top seal portion 17 is folded. Compared with the solution in which the second pole tab 40 extends from the first top seal portion 12 and the two are bent together, the bending rebound force generated by the folding of the first top seal portion 12 is smaller, that is, the degree of warping of the first top seal portion 12 is reduced, and the space occupied by the first top seal portion 12 in the third direction Z after being bent is reduced, thereby reducing the space occupied by the head of the secondary battery, thereby improving the capacity of the secondary battery.

[0078] Of course, the arrangement of the first tab 30 and the second tab 40 can be adaptively adjusted according to actual usage requirements. For example, as shown in FIG2 , in other embodiments, the first tab 30 and the second tab 40 are respectively located on opposite sides of the packaging bag 10. The first tab 30 extends from the first gap 14 at the head of the secondary battery, and the second tab 40 extends from the second gap 15 at the tail of the secondary battery. This reduces the space occupied at both the head and tail of the secondary battery, which is also beneficial to increasing the capacity of the secondary battery.

[0079] Regarding the specific structure of the packaging bag 10, it includes a first film sheet 101 and a second film sheet 102. The first film sheet 101 and the second film sheet 102 can be provided as a whole or separately. For example, as shown in FIG5 , the first film sheet 101 and the second film sheet 102 can be formed by folding a film material with a composite layer structure. In specific implementation,

[0080] First, a first notch 1011 is punched out at a first corner of the first diaphragm 101, and a second notch 1021 is punched out at a position corresponding to the first notch 1011 at the first corner of the second diaphragm 102; a third notch 1012 is punched out at a second corner of the first diaphragm 101, and a fourth notch 1022 is punched out at a position corresponding to the third notch 1012 at the second corner of the second diaphragm 102;

[0081] Next, at least one of the first diaphragm 101 and the second diaphragm 102 is punched to form at least one pit;

[0082] Then, the middle part of the membrane is folded along the fold line to cover the electrode assembly 20;

[0083] Then, seal all the edges except the part where the pit is located, hot press the first corner to melt and form the first tab glue 32, the first diaphragm 101, and the second diaphragm 102, and hot press the second corner to melt and form the second tab glue 42, the first diaphragm 101, and the second diaphragm 102.

[0084] The two edge seals adjacent to the first notch 1011 are the aforementioned first top seal portion 12 and the first side seal portion 13 , and the edge seal arranged opposite to the first side seal portion 13 along the second direction Y is the second side seal portion 16 .

[0085] The closed space formed by punching, stretching and packaging at least one of the first diaphragm 101 and the second diaphragm 102 is the aforementioned accommodation cavity.

[0086] The first top sealing portion 12 is bent toward the first direction X and is used to be partially fitted with the first top wall 1131 .

[0087] A side edge of the first top seal portion 12 along the second direction Y and a side edge of the first side seal portion 13 along the third direction Z define a boundary of the first gap 14 .

[0088] The other side edge of the first top seal portion 12 along the second direction Y and the side edge of the second side seal portion 16 along the third direction Z define a boundary of the second gap 15 .

[0089] In some embodiments, the composite layer structure includes a first polymer layer, a metal layer, and a second polymer layer, which are stacked sequentially from inside the accommodating cavity to outside the accommodating cavity to form the aforementioned first diaphragm 101 and / or second diaphragm 102.

[0090] The first polymer layer melts at a predetermined temperature and has adhesive properties, facilitating packaging of the packaging bag 10. Examples of materials for the first polymer layer include polyethylene, polypropylene, polycarbonate, polyamide, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer, polyoxymethylene, and polyphenylene ether. As a result, the first polymer layer is difficult to dissolve or swell in 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 infiltration into the containment cavity and to enhance the structural strength of the packaging bag 10. Examples of materials for such a metal layer include aluminum foil and austenitic-ferritic duplex stainless steel foil. The metal layer reacts with oxygen in the air to form a dense oxide film, thereby reducing the risk of moisture infiltration into the containment cavity.

[0092] The second polymer layer is used to reduce the risk of air infiltration into the receiving cavity and improve the deformability of the packaging bag 10. Examples of materials for making 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 embodiments of the present application do not specifically limit the packaging method between the first membrane 101 and the second membrane 102. For example, the first membrane 101 and the second membrane 102 can be fixedly connected by gluing or hot pressing, or they can be first pressed and then heat-sealed, or other processes can be used to achieve the fixed connection between the first membrane 101 and the second membrane 102.

[0094] It is also understood that the structure of the packaging bag 10 is actually diverse and is not limited to the specific structure of the packaging bag 10 mentioned above. It only needs to serve as a container for the electrode assembly 20 and have a deformation capability similar to that of the packaging bag 10 described above. In addition, the packaging bag 10 should be configured so that a first gap 14 is formed between a side edge of the first top seal portion 12 along the second direction Y and a side edge of the bent first side seal portion 13 along the third direction Z. This first gap 14 allows the other end of the first electrode tab 30 to extend.

[0095] In some embodiments, the first side seal portion 13 and / or the second side seal portion 16 are bent in the first direction X. The first side seal portion 13 is configured to mate with the first side wall 1132, and the second side seal portion 16 is configured to mate with the second side wall 1134. This reduces the space occupied by the secondary battery within 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 a side edge of the bent first top seal portion 12 along the second direction Y and a side edge of the bent first side seal portion 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 and shorts the exposed metal layer on the packaging bag 10 arranged around its outer circumference, in some embodiments, along the third direction Z, one end of the first tab glue 32 extends beyond the edge of one side of the packaging bag 10 where the first tab glue 32 is encapsulated.

[0097] Furthermore, when viewed along the second direction Y, the projection of the first tab glue 32 extending beyond the first top wall 1131 along the third direction Z overlaps with the projection of the first top seal portion 12. This arrangement has the advantage of wasting space at the head of the battery due to the height restriction of the first tab glue 32 during the distance the first tab glue 32 extends beyond the edge of a side of the packaging bag 10 encapsulating the first tab glue 32. By arranging for the first top seal portion 12 to overlap with the first tab glue 32 along the third direction Z, this wasted space can be better utilized, thereby improving energy density. A portion of this space is offset by the space occupied by the first top seal portion 12 in the third direction Z, thereby further reducing the head space occupied by the secondary battery and 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 belt 41 contacts and shorts the exposed metal layer on the packaging bag 10 arranged around its outer circumference, in some embodiments, along the third direction Z, one end of the second tab glue 42 extends beyond the edge of one side of the packaging bag 10 where the second tab glue 42 is encapsulated.

[0099] Furthermore, when viewed along the second direction Y, the projection of the portion of the second tab glue 42 extending beyond the packaging bag 10 along the third direction Z overlaps with the projection of the second top seal 17. With this arrangement, a portion of the distance that the second tab glue 42 extends beyond the edge of the packaging bag 10 encapsulating the second tab glue 42 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 thereby further increasing the capacity of the secondary battery.

[0100] FIG6 is a partial enlarged view of a portion c of the secondary battery shown in FIG5 .

[0101] 5 and 6 , in some embodiments, the electrode assembly 20 includes a first electrode piece 21, a second electrode piece 22 having a different polarity from the first electrode piece 21, and a separator 23 separating the first electrode piece 21 and the second electrode piece 22. One of the first electrode piece 21 and the second electrode piece 22 is electrically connected to the first electrode tab 30, and the other is electrically connected to the second electrode tab 40.

[0102] For ease of description, the following embodiments are all illustrated by taking the first electrode 21 as the positive electrode and the second electrode 22 as the negative electrode.

[0103] The first electrode sheet 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 in the accommodation cavity.

[0104] It is understandable that the various embodiments of the present application do not specifically limit the electrical connection method between the first electrode tab 30 and the first current collector. For example, in some embodiments, the first electrode tab 30 and the first current collector are different parts of the same component. In specific implementation, the first electrode tab 30 and the first current collector that matches the shape of the main body 11 can be die-cut on a complete metal foil, and then the first active material layer is coated on at least one surface of the first current collector to form the first electrode sheet 21. For another example, in other embodiments, the first electrode 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 on the first current collector coated with the first active material layer, and then the first electrode tab 30 is 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, copper foil, etc. 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 sheet 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 extending into the accommodation 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, mesocarbon microbeads, silicon-based materials, tin-based materials, lithium carbonate, or other metals that can form alloys with lithium.

[0110] It is understood that the various embodiments of the present application do not specifically limit the electrical connection method between the second electrode tab 40 and the second current collector. Since the connection method between the second electrode tab 40 and the second current collector is similar to the connection method between the first electrode tab 30 and the first current collector, please refer to the description of the connection method between the first electrode 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 have a laminated structure. Specifically, there are at least two first electrode sheets 21 and at least two second electrode sheets 22. The at least two first electrode sheets 21 and the at least two second electrode sheets 22 are alternately stacked along a first direction X, and an isolation film 23 separates the first electrode sheets 21 and the second electrode sheets 22.

[0112] In some embodiments, along the third direction Z, electrical connections between the plurality of first electrode sheets 21 and the first electrode tabs 30 are arranged opposite to the first gap 14 .

[0113] In some embodiments, along the third direction Z, the electrical connection points between the plurality of second electrode sheets 22 and the second electrode tabs 40 are arranged opposite to the second gap 15 .

[0114] Alternatively, the electrode assembly 20 may be a wound structure. Specifically, the first electrode sheet 21 and the second electrode sheet 22 are both in strip-like structures. The first electrode sheet 21, the separator 23, and the second electrode sheet 22 are stacked in sequence and wound two or more times.

[0115] Of course, the electrode assembly 20 may also be other components besides a stacked structure or a wound structure, as long as it can realize the charge and discharge functions of the secondary battery.

[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 above, but different therefrom, as shown in FIG12 or FIG13 , in some embodiments, the packaging bag 10 has a first space S1 that communicates with 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 first space S1 that is connected to the first gap 14. It should be noted that as long as there is an uneven area along 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 between the first electrode 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 electrode tab 30 connection.

[0119] The first tab adhesive 32 is disposed on the second connecting wall 11352 , and one end of the first tab adhesive 32 along the third direction Z extends beyond the second connecting wall 11352 to the first space S1 .

[0120] Along the third direction Z, the other end of the first metal strip 31 sequentially passes through the accommodating cavity, the first tab glue 32 , the first space S1 and the first gap and extends out of the packaging bag 10 .

[0121] In the secondary battery involved in the present application, the distance that the first pole ear glue 32 exceeds the second connecting wall 11352 can be accommodated in the first space S1, or the distance that the first pole ear glue 32 exceeds the second connecting wall 11352 can be accommodated in the space enclosed by the first space S1 and the first top seal portion 12, so that the head space occupied by the secondary battery is further reduced, and the capacity of the secondary battery can be further improved.

[0122] In some embodiments, the second connecting wall 11352 and the first top wall 1131 are both arranged parallel to the first direction X, thereby facilitating the subsequent packaging 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 ensure a smooth transition between the first top wall 1131 and the first connecting wall 11351 .

[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 ensure a smooth transition between the first connecting wall 11351 and the second connecting wall 11352 .

[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 ensure a smooth transition between the second connecting wall 11352 and the first side wall 1132 .

[0126] It will be appreciated that the various embodiments of the present application do not limit the specific shape of the first space S1. For example, as shown in Figures 12 and 13, in some embodiments, when viewed along the first direction X, the cross-sectional shape of the first space S1 is generally rectangular. For another example, 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 can be triangular or have other shapes.

[0127] Continuing with FIG. 12 , in some embodiments, the packaging bag 10 has a second space S2 that 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 via the third connecting wall 11361 and is recessed relative to the first top wall 1131 in the third direction Z. The third connecting wall 11361 and the fourth connecting wall 11362 enclose the second space S2 that communicates with the second gap. It should be noted here that as long as there is an uneven area in the component of the third top wall 1136 in the third direction Z, it can be determined that the second top wall 1136 is recessed toward the third direction Z relative to the first top wall 1131, which can bring the connection between the second pole ear 42 and the electrode assembly 20 closer to the center of the packaging bag 10 and reduce the space occupied by the second pole ear 42 connection.

[0128] The second tab adhesive 42 is disposed on the fourth connecting wall 11362 , and one end of the second tab adhesive 42 along the third direction Z extends beyond the fourth connecting wall 11362 to the second space S2 .

[0129] Along the third direction Z, the other end of the second metal strip 41 passes through the second tab glue 42 , the second space S2 , and the second gap 15 in sequence and extends out of the packaging bag 10 .

[0130] The advantage of adopting this technical solution is that the distance that the second pole ear glue 42 exceeds the fourth connecting wall 11362 can be accommodated in the second space S2, or the distance that the second pole ear glue 42 exceeds the fourth connecting wall 11362 can be accommodated in the space enclosed by the second space S2 and the first top seal portion 12, and the space dimensions occupied in the third direction Z are offset together, so that the space occupied by the head of the secondary battery is further reduced, and the capacity of the secondary battery can be further improved.

[0131] In some embodiments, the fourth connecting wall 11362 and the first top wall 1131 are both arranged parallel to the first direction X, thereby facilitating the subsequent packaging of the bag body 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 ensure a smooth transition between the first top wall 1131 and the third connecting wall 11361 .

[0133] In some embodiments, a rounded corner is provided at the connection between the third connecting wall 11361 and the fourth connecting wall 11362 to ensure a smooth transition between the third connecting wall 11361 and the fourth connecting wall 11362 .

[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 ensure a smooth transition between the fourth connecting wall 11362 and the second side wall 1134 .

[0135] It will be appreciated that the various embodiments of the present application do not limit the specific shape of the second space S2. For example, as shown in Figure 12, in some embodiments, when viewed along the first direction X, the cross-section of the second space S2 is generally rectangular. For another example, in other 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 can be triangular or have other shapes.

[0136] Third embodiment

[0137] For ease of description, the same reference numerals are used throughout this application to identify components with the same names. Based on the description of the first embodiment above, the difference is that:

[0138] As shown in FIG. 14 , FIG. 15 or FIG. 20 , in some embodiments, the packaging bag 10 has a first groove 191 , and the first groove 191 is communicated with the 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 via the first connecting wall 11351 and is recessed relative to the first top wall 1131 in the third direction Z.

[0140] The packaging bag 10 includes a second top seal portion 17, which is connected to the second connecting wall 11352 and extends outward. The second top seal portion 17 is respectively connected to the first top seal portion 12 and the first side seal portion 13. The first connecting wall 1135, the second top seal portion 17, and the second connecting wall 11352 together enclose the first groove 191.

[0141] The first tab adhesive 32 is disposed on the second top-sealing portion 17 , and one end of the first tab adhesive 32 along the third direction Z extends beyond a side edge of the second top-sealing portion 17 to the first gap.

[0142] Along the third direction Z, the other end of the first metal strip 31 passes through the accommodating cavity, the first tab glue 32 and the first gap in sequence and extends out of the packaging bag 10 .

[0143] In the secondary battery of the present 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, thereby maintaining a stable connection between the first tab adhesive 32 and the second seal, and reducing leakage between the first metal strip 31 and the second top seal 17. The first groove 191 is located at a corner of the main body 11, facilitating the hot pressing fixture's fixation and positioning of the first tab 30, thereby improving secondary battery assembly efficiency.

[0144] It is understood that the various embodiments of the present application do not limit the specific shape of the first groove 191. For example, as shown in Figures 14-16 or Figure 20, in some embodiments, the cross-sectional shape of the first groove 191, as viewed along the first direction X, is generally rectangular. For another example, in other embodiments, the second top wall 1135 is inclined, connecting the first top wall 1131 and the first side wall 1132. The second top wall 1135, the second top seal portion 17, and the first side wall 1132 collectively enclose the first groove 191. In this case, the first groove 191 may be a trapezoidal groove or other shape.

[0145] In some embodiments, the second connecting wall 11352 and the first top wall 1131 are both arranged parallel to the first direction X, thereby facilitating the subsequent packaging of the bag body and the first tab.

[0146] As shown in Figure 14, in some embodiments, the spacing S1 between the second connecting wall 11351 and the folded first top seal 12 along the third direction Z, the sum S2 of the distance the second top seal 17 extends beyond the second connecting wall 11351 and the distance the first tab glue 32 extends beyond the second top seal 17, and S1 and S2 satisfy the following: S1 ≥ S2. This eliminates the need to bend the first tab glue 32, while minimizing the impact on the volumetric energy density of the secondary battery. This mitigates the risk of leakage caused by insufficient connection strength around the first tab glue 32 due to bending.

[0147] As shown in Figures 14-16 or 20, in some embodiments, the edge of the second top seal portion 17 away from the second connecting wall 1136 is flush with the edge of the first side seal portion 13 along the third direction Z. This can reduce the number of processing steps for the packaging bag 10 and improve the production efficiency of secondary batteries. It should be noted that the flushing mentioned here is not strictly flush. Due to process tolerances, a range within 0.5 mm should be considered flush.

[0148] As shown in FIG. 14 , FIG. 15 , FIG. 17 or FIG. 20 , in some embodiments, the packaging bag 10 has a second groove 192 , and the second groove 192 is connected to the 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 via 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 the fourth connecting wall 11362 and extends out of the receiving cavity. The third top seal 18 is connected to the first top seal 12 and the second side seal 16. The third connecting wall 11361, the third top seal 18, and the fourth connecting wall 11362 together enclose the aforementioned second groove 192.

[0151] The second tab adhesive 42 is disposed on the third top-sealing portion 18 , and one end of the second tab adhesive 42 along the third direction Z extends beyond a side edge of the third top-sealing portion 18 to the second gap 15 .

[0152] Along the third direction Z, the other end of the second metal strip 41 passes through the accommodating cavity, the second tab glue 42 and the second gap 15 in sequence and extends out of the packaging bag 10 .

[0153] In the secondary battery of the present application, the presence of the third top seal 18 provides a larger contact area between the second tab adhesive 42 and the packaging bag 10, thereby maintaining a stable connection reliability between the second tab adhesive 42 and the third top seal 18 and 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, which facilitates 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 will be appreciated that the various embodiments of the present application do not limit the specific shape of the second groove 192. For example, as shown in Figures 11, 12, or 14, in some embodiments, the cross-section of the second groove 192, viewed along the first direction X, is generally rectangular. For another example, in other embodiments, the third top wall 1135 connects the first top wall 1131 and the second side wall 1134, and the third top wall 1135, the third top seal portion 18, and the second side wall 1134 collectively enclose the second groove 192. In this case, the first groove 192 may be a trapezoidal groove or other shape.

[0155] In some embodiments, the fourth connecting wall 11362 and the first top wall 1131 are both arranged parallel to the first direction X, thereby facilitating the subsequent packaging of the bag body and the second tab.

[0156] As shown in FIG. 14 , in some embodiments, the spacing S3 between the fourth connecting wall 11362 and the folded first top seal portion 12 along the third direction Z, the sum S4 of the distance the third top seal portion 18 extends beyond the fourth connecting wall 11362 and the distance the portion of the second tab adhesive 42 that extends beyond the edge of the third top seal portion 18 along the third direction Z, and S3 and S4 satisfy the following: S3 ≥ S4. This eliminates the need for bending the second tab adhesive 42, while minimizing the impact on the volumetric energy density of the secondary battery. This mitigates the risk of leakage caused by insufficient connection strength around the second tab adhesive 42 resulting from bending the second tab adhesive 42.

[0157] As shown in Figure 14 or Figure 20, in some embodiments, the side edge of the third top seal portion 18 away from the fourth connecting wall 11362 is flush with the side edge of the second side seal portion 16 along the third direction Z. Flush does not mean flush in the strict sense. Due to process tolerances, it should be flush within 0.5 mm. This can reduce the processing steps of the packaging bag 10 and improve the production efficiency of secondary batteries.

[0158] 18-20 , in some embodiments, the accommodating cavity includes a first cavity (not shown) and a second cavity (not shown) communicating with the first cavity. The first cavity can be enclosed by the second connecting wall 11352, the first side wall 1132, the bottom wall 1133, the second side wall 1134, the fourth connecting wall 11362, and the virtual line between the fourth connecting wall 11362 and the second connecting wall 11352. The second cavity can be enclosed by the first top wall 1131, the first connecting wall 1135, the virtual line between the fourth connecting wall 11362 and the second connecting wall 11352, and the 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 accommodated in the first cavity, and the protrusion 202 is accommodated in the second cavity. Specifically, any first electrode piece 21 includes a first electrode piece body (not shown) and a first protrusion (not shown) integrally connected to the first electrode piece body, any second electrode piece 22 includes a second electrode piece body (not shown) and a second protrusion (not shown) integrally connected to the second electrode piece body, and any isolation membrane 23 includes an isolation membrane body (not shown) and a third protrusion (not shown) integrally connected to the isolation membrane body. The electrode assembly body 201 can be formed by at least two first electrode piece bodies, at least two isolation membrane bodies, and at least two second electrode piece bodies alternately stacked in sequence along the first direction X. The protrusion 202 can be formed by at least a first protrusion, at least a third protrusion, and at least two second protrusions alternately stacked in sequence along the first direction X.

[0160] It should be noted that the difference between the first pole piece body and the first protrusion lies in their location; the rest of their structures are substantially the same, namely, both the first pole piece body and the first protrusion include a first current collector and a first active material layer. The difference between the second pole piece body and the second protrusion also lies in their location; the rest of their structures are substantially the same, namely, both the second pole piece 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 location; the rest of their structures are substantially the same.

[0161] In 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. Specifically, multiple first electrode sheet bodies are electrically connected to one end of the first electrode tab 30, and multiple second electrode sheet 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 connections between the plurality of first electrode sheet bodies and the first electrode tab 30 are arranged opposite the second connecting wall 11352. In other words, the electrical connections between the plurality of first electrode sheet bodies and the first electrode tab 30 may no longer be located in the portion of the second cavity opposite the first top seal 12. On the one hand, the gap between the protrusion 202 and the first top seal 12 is shortened, reducing the amount of free electrolyte accumulated in this region. This mitigates the risk of shorting caused by membrane contraction caused by excessive free electrolyte accumulation impacting the separator 23 of the protrusion 202. On the other hand, the heat sealing of the first top seal 12 is no longer affected by the first metal strip 31 and the first electrode tab adhesive 32, resulting in a stable connection strength. Furthermore, the outward extension of the first top seal 12 is also reduced because it is no longer affected by the first metal strip 31 and the first electrode tab adhesive 32, thereby further improving the volumetric energy density of the secondary battery.

[0163] Continuing with FIG. 17 , in some embodiments, along the third direction Z, a plurality of electrical connections between the second electrode body and the second electrode tab 40 and the fourth connecting wall 11362 are arranged relative to each other. Based on a mechanism similar to that described in the electrical connection between the first electrode body and the first electrode tab 30, it also has similar effects as in the aforementioned embodiments, which will not be described in detail here. In addition, when the first electrode tab 30 and the second electrode tab 40 are respectively located on opposite sides of the first top seal 12 along the second direction Y, even if the presence of the first space S1 and the second space S2 reduces the capacity of the secondary battery, compared to a folding top seal battery of the same size, the capacity increased by the protrusion 202 is still greater than the sum of the capacity reductions of the aforementioned two, that is, the total capacity of the secondary battery can still be improved. It should be noted that the multiple mentioned here specifically refers to two or more.

[0164] As shown in FIG19 , in some embodiments, along the third direction, the ends of multiple third protrusions extending beyond the second protrusions are interconnected and fixed to form a connecting portion (not shown), which can be fixed by heat pressing. This arrangement allows the integrated structure formed by the multiple third protrusions to increase the upper limit of the maximum impact stress resistance, thereby reducing the possibility of the isolation membrane 23 of the protrusion 202 being folded and shorted when free electrolyte impacts the isolation membrane.

[0165] In traditional battery cells, because 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. This results in a high failure rate for the connection portion and can cause separator shrinkage. The inventors of this application have experimentally demonstrated that limiting the length of the connection portion along the second direction Y to 15mm-120mm has resulted in a relatively good failure rate for this type of secondary battery in drop tests.

[0166] Furthermore, the length of the connecting portion along the second direction is 20 mm to 120 mm, thereby further increasing the connection strength of the connecting portion.

[0167] As shown in Figures 12-15, in some embodiments, one side edge of the first top seal portion 12 along the second direction Y extends beyond the first top wall 1131. This allows the first top seal portion 12 to maintain a certain safety distance from the first connecting wall 1135 at its connection location, ensuring a reliable seal at the connection location and minimizing damage and leakage at that location.

[0168] Similarly, the other side edge of the first top sealing portion 12 along the second direction Y exceeds the first top wall 1131 .

[0169] Another embodiment of the present application further provides an electrical device comprising any of the above-mentioned secondary batteries. The electrical device of the present application may be, but is not limited to, a laptop computer, a pen-type computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD television, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a lighting fixture, a toy, a game console, a clock, a power tool, a flashlight, a camera, a large household battery, and a lithium-ion capacitor, etc.

[0170] The above description is merely an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present 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. The first direction is perpendicular to the second direction, and is characterized in that Along the second direction, a first gap is formed between the first side sealing portion and the first top sealing portion; The first electrode tab includes a first metal strip and a first electrode tab glue arranged around the first metal strip, one end of the first metal strip is electrically connected to the electrode assembly, the first electrode tab glue is adhered to the packaging bag, and the other end of the first electrode tab passes through the first electrode tab glue and the first gap and extends out of the packaging bag.

2. The secondary battery according to claim 1, wherein The main body includes a second top wall, the second top wall is respectively connected to the first top wall and the first side wall, and the second top wall is recessed relative to the first top wall toward a third direction, wherein the third direction, the second direction, and the first direction are perpendicular to each other; The packaging bag includes a second top seal portion, the second top seal portion is provided on the second top wall, and the second top seal portion connects the first top seal portion and the first side seal portion; The other end of the first metal band passes through the second top seal portion and the first gap and extends out of the packaging bag.

3. The secondary battery according to claim 2, wherein The second top wall includes a first connecting wall and a second connecting wall, and the second connecting wall is connected to the first top wall through the first connecting wall; The second connecting wall and the first top wall are both arranged parallel to the first direction.

4. The secondary battery according to claim 3, wherein The first tab glue is provided on the second top sealing portion, and along the third direction, one end of the first tab glue exceeds a side edge of the second top sealing portion; When viewed along the second direction, a projection of the first tab glue extending beyond an edge of the second top-sealing portion overlaps with a projection of the first top-sealing portion.

5. The secondary battery according to claim 4, wherein The distance S1 between the second connecting wall along the third direction and the surface of the first top seal portion facing away from the first top wall, the sum of the distance between the second top seal portion close to one end of the second connecting wall and one end away from the second connecting wall and the distance between the first electrode ear glue and the edge portion of one side of the second top seal portion along the third direction S2, S1 and S2 satisfy: S1 ≥ S2.

6. The secondary battery according to any one of claims 2 to 5, characterized in that: The packaging bag includes a second side seal portion, the main body portion 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 portion is connected to the second side wall; Along the first direction, a second gap is formed between the second side sealing portion and the first top sealing portion; The secondary battery includes a second electrode tab, which includes a second metal strip and a second electrode tab glue wrapped around 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 electrode tab passes through the second electrode tab glue and the second gap and extends out of the packaging bag.

7. The secondary battery according to claim 6, characterized in that The main body includes a third top wall, the third top wall is connected to the first top wall and the second side wall respectively, and the third top wall is recessed relative to the first top wall in a third direction, wherein the third direction, the second direction, and the first direction are perpendicular to each other; The packaging bag includes a third top seal portion, the third top seal portion is provided on the third top wall, and the third top seal portion connects the first top seal portion and the second side seal portion; The other end of the second metal band passes through the third top seal portion and the second gap and extends out of the packaging bag.

8. The secondary battery according to claim 7, wherein: 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; The fourth connecting wall and the first top wall are both arranged parallel to the first direction.

9. The secondary battery according to claim 8, characterized in that The second tab glue is provided on the third top sealing portion, and along the third direction, one end of the second tab glue exceeds a side edge of the third top sealing portion; When viewed along the second direction, a projection of the second tab glue extending beyond an edge portion of one side of the third top-sealing portion overlaps with a projection of the first top-sealing portion.

10. The secondary battery according to claim 9, wherein 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 convex portion integrally connected to the electrode assembly body, the electrode assembly body is accommodated in the first cavity, and the convex portion is accommodated 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 piece, a second electrode piece, and an isolation film separating the first electrode piece from the second electrode piece; The first pole piece includes a first pole piece body and a first protruding portion integrally connected to the first pole piece body; The second pole piece includes a second pole piece body and a second protruding portion integrally connected to the second pole piece body; The isolation diaphragm includes an isolation diaphragm body and a third protruding portion integrally connected to the isolation diaphragm body; The electrode assembly body is formed by alternatingly stacking the first pole piece body, the isolation membrane body and the second pole piece body, and the convex portion is formed by alternatingly stacking the first protruding portion, the third protruding portion and the second protruding portion.

11. The secondary battery according to claim 10, wherein Along the third direction, the connection between the electrode assembly body and the first metal strip is arranged opposite to the second top wall; and / or Along the third direction, a connection between the electrode assembly body and the second metal belt is arranged opposite to the third top wall.

12. The secondary battery according to claim 10, characterized in that The number of the third protrusions is at least two. Along the third direction, ends of at least two of the third protruding portions extending beyond the second protruding portion 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 portion along the second direction is 15 mm to 120 mm.

14. The secondary battery according to any one of claims 9 to 13, characterized in that: The second side seal portion is bent toward the first direction; and / or The first side sealing portion is bent toward the first direction.

15. An electrical device, characterized in that: The invention comprises the secondary battery according to any one of claims 1 to 14.

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