Secondary battery and electrical device
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-09-09
- Publication Date
- 2026-08-13
Smart Images
Figure CN2024117700_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] During the tab encapsulation process, the tab adhesive is squeezed to at least one side, and excess adhesive overflows from the encapsulation area and squeezes into the encapsulation area near the adjacent side seal. After curing, the excess adhesive forms a large clump. In the subsequent folding and sealing process, the clump can easily interfere with the folded side seal. Because the clump is harder than the packaging bag, the side seal adjacent to the clump is easily scratched by the clump under external force, leading to battery damage and affecting the safety and reliability of the secondary battery.
[0003] Application content
[0004] The purpose of this application is to provide a secondary battery and an electrical device that improves the interference between the overflow adhesive block and its adjacent and folded side seal, thereby enhancing the safety and reliability of the secondary battery.
[0005] According to a first aspect of this application, a secondary battery is provided, including a packaging bag, an electrode assembly, and tabs. The packaging bag includes a main body, a first sealing portion, and a second sealing portion. The electrode assembly is disposed within the main body. The main body includes a first wall and a second wall. The first wall and the second wall are connected. The first sealing portion is connected to the first wall, and the second sealing portion is connected to the second wall. A gap is formed between the second sealing portion and the first sealing portion along a second direction. The tab includes tab adhesive, which includes a tab adhesive body and an extension portion integrally connected to the tab adhesive body. The tab adhesive body is adhered to the packaging bag, and the extension portion extends beyond the packaging bag along a third direction. When viewed along the third direction, the projection of the extension portion falls within the gap. The thickness direction of the electrode assembly is perpendicular to each other along the third direction, the second direction, and the first direction. Along the second direction, the distance D1 between the extension portion and the second sealing portion satisfies: 0.5mm ≤ D1 ≤ 3mm.
[0006] In the secondary battery involved in this application, limiting D1 to this size range can reduce the interference between the excess adhesive and the second sealing part, thereby improving the safety and reliability of the secondary battery; it can also reduce size redundancy, thereby increasing the energy density of the secondary battery.
[0007] In one or more of the above optional embodiments, 0.8mm ≤ D1 ≤ 2mm. By adjusting D1 within this size range, the safety and reliability of the secondary battery are improved, and its size redundancy is reasonably controlled, thereby further improving the energy density of the secondary battery.
[0008] In one or more of the above optional embodiments, 0.8mm ≤ D1 ≤ 1mm. By adjusting D1 within this size range, the safety and reliability of the secondary battery are optimized, and its size redundancy control is more reasonable, thereby maximizing the energy density improvement of the secondary battery.
[0009] In one or more of the above optional embodiments, the first sealing part is bent toward a first direction, and the second sealing part is bent toward the first direction, where the first direction is the thickness direction of the electrode assembly.
[0010] In one or more of the above optional embodiments, the main body includes a third wall, which is connected to the first wall and the second wall respectively. The packaging bag includes a third sealing portion, which is connected to the third wall. The tab adhesive body is adhered to the third sealing portion, and the protruding portion extends beyond the edge of the third sealing portion away from the third wall in a third direction.
[0011] In one or more of the above optional embodiments, the third wall includes a first connecting wall and a second connecting wall. The first connecting wall is integrally connected to both the first wall and the second connecting wall, and is recessed in a second direction relative to the second wall. The second wall is integrally connected to the first connecting wall via the second connecting wall, and is recessed in a third direction relative to the first wall. The third sealing portion is integrally connected to the first connecting wall, the second connecting wall, the second sealing portion, and the first sealing portion.
[0012] In one or more of the above optional embodiments, along the third direction, the edge of the third sealing portion away from the third wall does not extend beyond the first wall. This arrangement shortens the length of the protruding part from the gap, thereby improving the space utilization rate of the secondary battery.
[0013] In one or more of the above optional embodiments, the distance D2 between the protruding part and the first sealing part along the second direction satisfies: 0.3mm ≤ D2 ≤ 2.5mm. Limiting D2 within this size range can provide sufficient area for overflow adhesive to be contained after the tab adhesive body is encapsulated, while reducing the interference between the overflow adhesive block and the first sealing part, so as to minimize the energy density loss of the secondary battery.
[0014] In one or more of the above optional embodiments, 0.6mm ≤ D2 ≤ 1.8mm.
[0015] In one or more of the above optional embodiments, D1 ≥ D2. This makes the position of the tabs at the third sealing part more reasonable, further reducing design redundancy and improving the drop resistance 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. 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 electrode tab is electrically connected to the electrode assembly body. The electrode assembly includes multiple electrode sheets and multiple separator membranes. The electrode sheet includes an electrode sheet body and a first protrusion integrally connected to the electrode sheet body. The separator membrane includes a separator membrane body and a second protrusion integrally connected to the separator membrane body. The electrode assembly body is formed by stacking multiple electrode sheet bodies and multiple separator membrane bodies, and the protrusion is formed by stacking the first protrusion and the second protrusion.
[0017] In one or more of the above optional embodiments, the tab includes a metal strip within the main body, one end of which is electrically connected to the electrode assembly, and the other end of which extends out of the packaging bag through a gap. Along the second direction, the distance D3 between one edge of the metal strip and the protruding portion satisfies: 0.8mm ≤ D3 ≤ 2.5mm.
[0018] In one or more of the above optional embodiments, an empty foil area is provided at one corner of the electrode, and a notch is provided at the other corner of the electrode. The notch is used to avoid the empty foil area of the adjacent electrode. Along the second direction, a protrusion is provided between the notch and the empty foil area.
[0019] In one or more of the above optional embodiments, the tab includes a metal strip within the main body, one end of which is electrically connected to the electrode assembly, and the other end of which extends out of the packaging bag through a gap. Along the second direction, the distance D4 between the other edge of the metal strip and the protruding portion satisfies: 0.8mm ≤ D4 ≤ 2.5mm.
[0020] According to a second aspect of this application, an electrical device is provided, comprising the aforementioned secondary battery.
[0021] 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
[0022] 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.
[0023] Figure 1 is a schematic diagram of the structure of a secondary battery provided in one embodiment of this application;
[0024] Figure 2 is a schematic diagram of the structure of another secondary battery provided in one embodiment of this application;
[0025] Figure 3 is an exploded view of the secondary battery structure shown in Figure 2;
[0026] Figure 4 is a schematic diagram of the structure of one of the electrode plates in the electrode assembly of the secondary battery shown in Figure 3;
[0027] Figure 5 is a magnified view of the secondary battery shown in Figure 2 from another angle.
[0028] 10. Packaging bag; 11. Main body; 111. First main wall; 112. Second main wall; 113. First wall; 114. Second wall; 115. Third wall; 1151. First connecting wall; 1152. Second connecting wall; 116. Fourth wall; 117. Fifth wall; 12. First sealing part; 13. Second sealing part; 14. Third sealing part;
[0029] 20. Electrode assembly; 201. Electrode assembly body; 202. Protrusion; 2011. Electrode sheet body; 2012. First protruding part; 20111. Empty foil area; 2011a. Notch;
[0030] 30. Electrode tab; 31. Metal strip; 32. Electrode tab adhesive; 322. Extended part;
[0031] X, first direction; Y, second direction; Z, third direction. Detailed Implementation
[0032] 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.
[0033] 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.
[0034] 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.
[0035] 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".
[0036] 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°.
[0037] 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.
[0038] 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.
[0039] As shown in Figures 1 to 5, 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.
[0040] In some embodiments, the first direction X is parallel to the direction in which the first main wall and the second main wall of the packaging bag are disposed opposite each other, as will be described below; in addition, the first direction X is also parallel to the direction in which the electrodes in the electrode assembly are stacked, as will be described below.
[0041] In some embodiments, the second direction Y is parallel to the direction in which the second wall and the fifth wall of the packaging bag are disposed opposite each other, as will be described below; in addition, the second direction Y is also parallel to the opposite side edges of the metal strip, as will be described below.
[0042] In some embodiments, the third-party direction Z is parallel to the direction in which the first wall and the fourth wall of the packaging bag are disposed opposite to each other, as will be described below; furthermore, the third-party direction Z is also parallel to the extension direction of the tab, as will be described below.
[0043] First Embodiment
[0044] Figure 1 is a schematic diagram of a secondary battery provided in one embodiment of this application. As shown in Figure 1, the secondary battery includes: a packaging bag (not shown), an electrode assembly 20, and a tab 30; the electrode assembly 20 is disposed inside the packaging bag; one end of the tab 30 is electrically connected to the electrode assembly 20 inside the packaging bag, and the other end of the tab 30 extends out of the packaging bag; the portion of the tab 30 extending out of the packaging bag is configured to be electrically connected to an electronic device.
[0045] 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.
[0046] The packaging bag is generally flat and includes a main body 11 and a plurality of sealing portions. The main body 11 has a first main wall 111, a second main wall 112, and a peripheral wall (not shown). The peripheral wall extends between the first main wall 111 and the second main wall 112 and surrounds and connects to the periphery of the first main wall 111 and the periphery of the second main wall 112. The first main wall 111, the second main wall 112, and the peripheral wall define a receiving cavity for accommodating the electrode assembly 20. The plurality of sealing portions are integrally connected to the periphery of the peripheral wall to form a closed container for encapsulating the electrode assembly 20.
[0047] Specifically, the peripheral wall includes a first wall 113, a second wall 114 and a third wall 115. The first wall 113 is connected to the second wall 114 through the third wall 115, and the first wall 113 and the second wall 114 are set at an angle.
[0048] The plurality of sealing portions include a first sealing portion 12 and a second sealing portion 13. The first sealing portion 12 extends outward from the first wall 113 and bends in the first direction X, and the second sealing portion 13 extends outward from the second wall 114 and bends in the first direction X.
[0049] Along the second direction Y, a gap 1a is formed between the second sealing part 13 and the first sealing part 12, and the gap 1a is configured to allow the tab 30 to pass through and extend out of the packaging bag.
[0050] Continuing with Figure 1, in some embodiments, the packaging bag may have a flat rectangular shape. The first main wall 111 and the second main wall 112 are generally flat and parallel to each other, and each main wall has the same size and the same generally rectangular shape. The peripheral walls can be considered as four consecutive walls connected in sequence, that is, the peripheral walls include not only the first wall 113, the second wall 114, and the third wall 115, but also the fourth wall 116 and the fifth wall 117. The first wall 113, the third wall 115, the second wall 114, the fourth wall 116, and the fifth wall 117 are connected end to end in a clockwise direction and are integrally connected to the perimeter of the first main wall 111 and the perimeter of the second main wall 112, respectively. In this flat rectangular configuration, the first main wall 111 and the second main wall 112 are arranged opposite each other along the first direction X, the second wall 114 and the fifth wall 117 are arranged opposite each other along the second direction Y, and the first wall 113 and the fourth wall 116 are arranged opposite each other along the third direction Z.
[0051] As can be seen from Figure 1, in some embodiments, the first wall 113 and the third wall 115 are different portions of the wall extending along the second direction Y in the peripheral wall. Viewed along the third direction Z, the first wall 113 is at least partially covered by the first sealing portion 12, and the third wall 115 is exposed at the gap 1a.
[0052] It is understood that the shape of the packaging bag is not limited to this and can be adapted to meet actual usage needs. For example, in alternative embodiments, the packaging bag may be circular, elliptical, or rectangular with rounded corners. In other words, the first main wall 111 and the second main wall 112 may be circular, elliptical, or shaped as a rectangle with rounded corners, and the peripheral wall may be considered as a single wall or multiple consecutive walls connected in sequence.
[0053] In some embodiments, the packaging bag may be made of two separate packaging films (not shown), with the two packaging films forming a main body 11 having the aforementioned receiving cavity in the middle. The main body 11 is sealed together to form a plurality of sealing portions, and the first sealing portion 12 and the second sealing portion 13 of the plurality of sealing portions are both bent toward a first direction X. In this embodiment, a recess is punched into one packaging film, and the other packaging film is sealed together with the aforementioned packaging film around the recess to form a plurality of sealing portions.
[0054] Alternatively, in some embodiments, the packaging bag may be made from a single packaging film that is folded in half to form two connected parts, with a recess punched into one part of the packaging film, and then folded in half to seal the recess to form the main body 11 and a plurality of sealing portions surrounding the main body 11.
[0055] In both of the aforementioned packaging bag configurations, each packaging film includes an outer protective layer (not shown), an inner fusion layer (not shown), and a metal layer (not shown) formed between the outer protective layer and the inner fusion layer. Exemplarily, the outer protective layer includes, but is not limited to, nylon; the inner fusion layer includes, but is not limited to, polypropylene; and the metal layer includes, but is not limited to, aluminum foil or steel foil. In the sealing section, the inner fusion layers of the two packaging films are fused together. Since the inner fusion layer is generally a hot-melt plastic material (polypropylene), the inner fusion layers of the two packaging films on the sealing section can be fused together by hot pressing.
[0056] The electrode assembly 20 includes a positive electrode (not shown), a negative electrode (not shown), and a separator (not shown) separating the positive and negative electrodes, one of which is electrically connected to the tab 30.
[0057] The positive electrode includes a positive current collector (not shown) and a positive active material layer (not shown) coated on at least one surface of the positive current collector. The positive current collector is electrically connected to the tab 30.
[0058] The positive 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 positive current collector is made of aluminum foil.
[0059] The positive electrode 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.
[0060] The negative electrode includes a negative current collector and a negative active material layer (not shown) coated on at least one surface of the negative current collector (not shown). The negative current collector is electrically connected to the second electrode tab 30.
[0061] The negative electrode 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 negative electrode current collector is made of copper foil.
[0062] The negative electrode active material layer includes, but is not limited to, one or more of the following: 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.
[0063] As shown in Figure 3, in some embodiments, the electrode assembly 20 may be a stacked structure. Specifically, there are at least two positive electrode sheets and at least two negative electrode sheets, which are stacked alternately along the first direction X, and a separator separates the positive and negative electrode sheets.
[0064] Alternatively, the electrode assembly 20 can be a wound structure. Specifically, there is one positive electrode and one negative electrode, and both the positive and negative electrode are strip-shaped structures. The positive electrode, the separator, and the negative electrode are stacked in sequence and wound two or more times.
[0065] 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 function of charging and discharging the secondary battery.
[0066] In some embodiments, the secondary battery includes an electrolyte that is contained within a cavity and permeates the positive electrode, the negative electrode, and the separator.
[0067] Referring to Figures 2 and 3, in some embodiments, the tab 30 includes a metal strip 31 and tab adhesive 32 surrounding the metal strip 31. The tab adhesive 32 includes a tab adhesive body and an extension portion 322 integrally connected to the tab adhesive body. The tab adhesive body is bonded and fixed to the third wall 115. The extension portion 322 extends beyond the third wall 115 along the third direction Z, and when viewed along the third direction Z, its projection falls within the gap 1a. One end of the metal strip 31 is electrically connected to the electrode assembly 20 within the receiving cavity, and the other end of the metal strip 31 extends out of the packaging bag through the gap 1a.
[0068] In some embodiments, the tab 30 can be a positive tab or a negative tab. If the tab 30 is a positive tab, it is electrically connected to the positive electrode plate. If the tab 30 is a negative tab, it is electrically connected to the negative electrode plate.
[0069] For ease of explanation, the following example uses tab 30 as the positive tab to describe the specific connection method between tab 30 and electrode assembly 20.
[0070] It is understood that the embodiments of this application do not specifically limit the electrical connection method between the tab 30 and the positive electrode plate.
[0071] For example, the metal strip 31 and the positive current collector are different parts of the same component. In a specific implementation, the metal strip 31 and the positive current collector adapted to the shape of the main body 11 can be die-cut from a complete metal foil, and then a positive active material layer can be coated on at least one surface of the positive current collector to form a positive electrode sheet.
[0072] For example, the tab 30 and the positive current collector are separate components. In a specific implementation, a groove can be scraped out on the positive current collector coated with a positive active material layer to expose the surface of the positive current collector, and then the metal strip 31 can be fixed to the surface of the positive current collector in the groove by means of, but not limited to, laser welding.
[0073] Referring to Figure 2 and also to Figure 3, in some embodiments, along the third direction Z, the electrode tab 30 and the electrical connection points and gaps 1a of the plurality of positive electrode plates are arranged opposite to each other.
[0074] It is also understood that the structure and shape of the metal strip 31 are not limited in the embodiments of this application. For example, the metal strip 31 can be a long strip structure, and its size can be adapted to actual needs. For example, the width of the metal strip 31 along the second direction Y can be 2mm to 6mm, and more preferably, the width of the metal strip 31 along the second direction Y is 2mm to 4mm. The material of the metal strip 31 includes, but is not limited to, aluminum, nickel, copper, and copper-plated nickel alloys. For example, when the tab 30 is a positive tab, the material of the metal strip 31 can be aluminum or aluminum-plated nickel; when the tab 30 is a negative tab, the material of the metal strip 31 can be copper-plated nickel.
[0075] Please refer back to Figure 1 or Figures 2 and 5. In some embodiments, along the second direction Y, the distance D1 between the protruding portion 322 and the second sealing portion 13 satisfies: 0.5mm ≤ D1 ≤ 3mm. Limiting D1 to this size range can reduce interference between the excess adhesive and the second sealing portion 13, thereby improving the safety and reliability of the secondary battery; it can also reduce dimensional redundancy, thereby increasing the energy density of the secondary battery. This point will be described in conjunction with subsequent test results. It should be noted that the distance D1 between the protruding portion 322 and the second sealing portion 13 along the second direction Y specifically refers to the distance between the edge of the protruding portion 322 near the second sealing portion 13 and the edge of the second sealing portion 13 near the protruding portion 322 along the second direction Y, that is, the shortest distance between the protruding portion 322 and the second sealing portion 13.
[0076] Furthermore, 0.8mm ≤ D1 ≤ 2mm. With D1 controlled within this size range, the secondary battery exhibits superior safety and reliability while maintaining reasonable size redundancy, thus further improving its energy density. This can also be illustrated by subsequent test results.
[0077] Furthermore, 0.8mm ≤ D1 ≤ 1mm. With D1 controlled within this size range, the secondary battery achieves optimal safety and reliability while also exhibiting more reasonable size redundancy control, thus maximizing the energy density improvement. This can also be illustrated by subsequent test results.
[0078] Second Embodiment
[0079] In this application, the same reference numerals are used to identify structural elements with the same names in various embodiments. Based on the description of the foregoing embodiments, but differing from them in that...
[0080] As shown in Figures 2 and 3, in some embodiments, the packaging bag 10 defines a clearance space 1b communicating with the gap 1a. Specifically, the third wall 115 includes a first connecting wall 1151 and a second connecting wall 1152. The first connecting wall 1151 is integrally connected to both the first wall 113 and the second connecting wall 1152, and is recessed in a second direction Y relative to the second wall 114. The second wall 114 is integrally connected to the first connecting wall 1151 via the second connecting wall 1152, and the second connecting wall 1152 is recessed in a third direction Z relative to the first wall 113.
[0081] The packaging bag 10 includes a third sealing part 14, which is connected to the first connecting wall 1151 and the second connecting wall 1152 respectively, and the three together define the aforementioned clearance space 1b.
[0082] The tab adhesive body is bonded and fixed to the third sealing part 14. The protruding part 322 extends beyond the third sealing part 14 along the third direction Z and, when viewed along the third direction Z, the projection of the protruding part 322 falls into the gap 1a. One end of the metal strip 31 is electrically connected to the electrode assembly 20 inside the receiving cavity, and the other end of the metal strip 31 extends out of the packaging bag 10 through the gap 1a.
[0083] The advantages of adopting the aforementioned technical solution are as follows: First, the hot-pressing equipment or tool can easily extend into the clearance space 1b to hot-press and seal the tab adhesive 32 and the third sealing part 14, thereby improving the manufacturing efficiency of the secondary battery. Second, the connection strength between the tab adhesive 32 and the third sealing part 14 depends on the bonding width of the tab adhesive 32 in the third direction Z. Compared with the bonding width between the tab adhesive 32 and the third wall 115 along the third direction Z in Embodiment 1, the bonding width of the tab adhesive 32 in the third direction Z in this technical solution is larger, thus the connection strength between the tab 30 and the packaging bag 10 is higher.
[0084] In other embodiments, the third wall 115 extends obliquely relative to the first wall 113 and the second wall 114, that is, when viewed along the first direction X, there is an oblique notch between the first wall 113 and the second wall 114. It should be noted that as long as there is an uneven area in the component of the third wall 115 in the third direction Z, it can be considered that the second top wall is recessed in the third direction Z relative to the first top wall.
[0085] In some embodiments, along the third direction Z, the edge of the third sealing portion 14 away from the second connecting wall 1152 does not extend beyond the first wall 113. This arrangement shortens the length of the protruding portion 322 extending into the gap 1a, thereby improving the space utilization of the secondary battery.
[0086] As shown in Figure 2 or Figure 5, to improve the sealing effect at the corner of the first wall 113 and the third wall 115, in some embodiments, the edge of the first sealing part 12 near the tab 30 extends beyond the first connecting wall 1151 along the second direction Y, and the portion of the first sealing part 12 extending beyond the first connecting wall 1151 is integrally connected with the third sealing part 14. In this way, the edge of the first sealing part 12 near the tab 30 is at a large distance from both the first wall 113 and the first connecting wall 1151, thereby improving the sealing failure of the packaging bag 10 at the corner of the first wall 113 and the third wall 115, and thus achieving a good sealing effect in the area where the corner is located.
[0087] As shown in Figure 2, in some embodiments, the distance D2 between the protruding part 322 and the first sealing part 12 along the second direction Y satisfies: 0.3mm ≤ D2 ≤ 2.5mm. If D2 < 0.3mm, it means that the distance between the protruding part 322 and the first sealing part 12 is too small, and it also means that the tab adhesive body, which is a different part of the same component as the protruding part 322, is closer to the first connecting wall 1151. This makes the area of the overflow adhesive receiving area after the tab adhesive body is packaged smaller, causing the tab adhesive body to overflow into the folding area of the first sealing part 12, affecting the subsequent folding of the first sealing part 12. If D2 > 2.5mm, the design redundancy is too large, and the area of the overflow adhesive receiving area after the tab adhesive body is packaged is too large, thereby affecting the energy density of the secondary battery. Therefore, limiting D2 to this size range can provide sufficient overflow adhesive receiving area for the overflow adhesive after the tab adhesive body is packaged, and can also reduce the interference between the overflow adhesive block and the first sealing part 12, so as to minimize the energy density loss of the secondary battery. This will also be explained in conjunction with subsequent test results. It should be noted that the distance D2 between the protruding portion 322 and the first sealing portion 12 along the second direction Y specifically refers to the distance between the edge of the protruding portion 322 near the first sealing portion 12 and the edge of the first sealing portion 12 near the tab 30 along the second direction Y, i.e., the shortest distance between the protruding portion 322 and the first sealing portion 12. Preferably, 0.6mm ≤ D2 ≤ 1.8mm.
[0088] Furthermore, D1 ≥ D2. Therefore, the position of the tab 30 in the third sealing part 14 is more reasonable, further reducing design redundancy and improving the drop resistance of the secondary battery. This is because D1 is located at the corner of the secondary battery, while D2 is roughly at the end face. D1 is larger than D2, meaning it has a larger encapsulation area, resulting in a more significant cushioning effect during drops, thus further improving the drop resistance of the secondary battery. During the heat sealing process, the third sealing part 322 may experience glue overflow at the encapsulation point. The overflow direction is the second direction Y, and it easily extends to one side as an overflow block. When the overflow block interferes with the folded edge, it affects the strength of the folded edge. However, when the third wall 115 is recessed, because the encapsulation area of the third sealing part 14 is inside the packaging bag, the glue overflow has a smaller impact on the first sealing part 12, thus ensuring that D1 ≥ D2.
[0089] As shown in Figure 2 or Figure 5, to improve the sealing effect at the corner of the second wall 114 and the third wall 115, in some embodiments, the edge of the second sealing part 13 near the tab 30 extends beyond the second connecting wall 1152 in the third direction Z, and the portion of the second sealing part 13 extending beyond the second connecting wall 1152 is integrally connected with the third sealing part 14. In this way, the edge of the second sealing part 13 near the tab 30 is at a large distance from both the second wall 114 and the second connecting wall 1152, thereby improving the sealing failure of the packaging bag 10 at the corner of the second wall 114 and the third wall 115, and thus the area at this corner can have a good sealing effect.
[0090] It is worth mentioning that the smaller the area occupied by the clearance space 1b, the greater the energy density of the secondary battery. The size of the clearance space 1b is related to the size of the tab 30. Generally speaking, the specifications of the metal strip 31 are fixed. The area occupied by the clearance space 1b depends on the width of the tab adhesive 32 along the second direction Y. The width of the tab adhesive 32 covering the metal strip 31 in the second direction Y is fixed. The area occupied by the clearance space 1b is related to the distance between the metal strip 31 and the opposite side edges of the protrusion 322 in the second direction Y. The width of the protrusion 322 in the second direction Y is the same as the width of the tab adhesive body in the second direction Y.
[0091] As shown in Figure 5, in some embodiments, the distance D3 between the metal strip 31 and one side edge of the protruding portion 322 along the second direction Y satisfies: 0.8mm ≤ D3 ≤ 2.5mm. This maintains the current-carrying capacity of the tab 30 essentially unchanged while minimizing the area occupied by the clearance space 1b, thereby further improving the energy density of the secondary battery. Further, 0.8mm ≤ D3 ≤ 1.5mm. It should be noted that the distance between the metal strip 31 and one side edge of the protruding portion 322 along the second direction Y specifically refers to the distance between the side edge of the metal strip 31 facing the protruding portion 322 and the side edge of the protruding portion 322 along the second direction Y.
[0092] Similarly, continuing as shown in Figure 5, in some embodiments, the distance D4 between the metal strip 31 and the other edge of the protruding portion 322 along the second direction Y satisfies: 0.8mm ≤ D4 ≤ 2.5mm. This maintains the current-carrying capacity of the tab 30 essentially unchanged while minimizing the area occupied by the clearance space 1b, thereby further improving the energy density of the secondary battery. Furthermore, 0.8mm ≤ D4 ≤ 1.5mm. It should be noted that the distance between the metal strip 31 and the other edge of the protruding portion 322 along the second direction Y specifically refers to the distance between the metal strip 31 towards the other edge of the protruding portion 322 and the other edge of the protruding portion 322 along the second direction Y.
[0093] As shown in Figure 3, 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 formed by a first wall 113, a first connecting wall 1151, a second connecting wall 1152, and a virtual connection between the second connecting wall 1152 and a portion of the fifth wall 117. The second cavity may be formed by a second wall 114, a fourth wall 115, and a virtual connection between the first connecting wall and the remaining portion of the fifth wall 117.
[0094] 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 electrode includes an electrode body 2011 and a first protrusion 2012 integrally connected to the electrode body 2011, and each separator 23 includes a separator body (not shown) and a second protrusion (not shown) integrally connected to the separator body. The electrode assembly body 201 may be formed by alternatingly stacking at least two electrode bodies 2011 and at least two separator bodies along a first direction X. The protrusion 202 may be formed by alternatingly stacking at least a first protrusion 2012 and at least two second protrusions along a first direction X.
[0095] In some embodiments, an empty foil area 20111 is provided at one corner of the electrode, and a notch 2011a is provided at the other corner of the electrode. The notch 2011a is used to avoid the empty foil area 20111 of the adjacent electrode. Along the second direction Y, a first protrusion 2012 is provided between the notch 2011a and the empty foil area 20111. As shown in Figure 3, this is an electrode assembly consisting of multiple electrode sheets and a separator stacked together. The multiple electrode sheets are divided into positive electrode sheets and negative electrode sheets. One corner of the positive electrode sheet is provided with an empty foil area 20111, and the other corner is provided with a notch 2011a. The negative electrode sheet has an empty foil area 20111 and a notch 2011a in the opposite position. Therefore, the notch 2011a of the positive electrode sheet can avoid the empty foil area 20111 of the adjacent negative electrode sheet, and the notch 2011a of the negative electrode sheet can also avoid the empty foil area 20111 of the adjacent positive electrode sheet. The multiple empty foil areas 20111 are stacked together and finally electrically connected to the tab 30.
[0096] It should be noted that the difference between the electrode body 2011 and the first protrusion 2012 lies in their positions; the rest of their structures are largely the same. Both the electrode body 2011 and the first protrusion 2012 include a current collector and an active material layer. Similarly, the difference between the separator body and the second protrusion lies in their positions; the rest of their structures are largely the same.
[0097] Within the first cavity, the electrode assembly body is electrically connected to one end of the metal strip. The metal strip is connected to a corner of the electrode assembly body 201. Specifically, multiple electrode bodies 2011 of the same polarity are electrically connected to one end of the metal strip.
[0098] The present application is further illustrated below with reference to embodiments and comparative examples. Various tests and evaluations were performed according to the methods described below. Furthermore, unless otherwise specified, "parts" and "%" are quality standards. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present application.
[0099] Secondary battery drop impact + high temperature and humidity test:
[0100] Fully charge the secondary battery and then drop it freely from a height of 1.5 meters onto a smooth marble surface. The drop sequence is as follows: front-back-bottom-top-left-right-top-top-left-top-right-bottom-left-bottom-right. Each side or corner is dropped twice consecutively to complete one round. Each secondary battery undergoes 10 rounds of drops. After 10 rounds, place it in a high-temperature (≥60℃) and high-humidity (≥95%) environment for 24 hours. Measure the battery voltage and inspect its appearance. The battery passes the test if it does not overheat, catch fire, explode, leak, or emit smoke.
[0101] Example 1-1
[0102] The prepared positive electrode sheet (80mm×30mm), separator, and negative electrode sheet are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. The electrode assembly is then wound to obtain the electrode assembly. The electrode assembly is placed in a prepared packaging film, and moisture is removed at 80°C. A prepared electrolyte is injected, and the battery undergoes vacuum sealing, settling, formation, and hot-pressing to obtain a secondary battery. Specifically, D1 = 0.5mm, D2 = 0.6mm, and gap 1a = 6.1mm. Gap 1a is the sum of D1, D2, and D5, where D5 = 5mm, and D5 = D3 + D4 + the width of the metal strip along the second direction.
[0103] Examples 1-2
[0104] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 0.6 mm, D5 = 5 mm, and gap 1a = 6.4 mm.
[0105] Examples 1-3
[0106] The difference from Example 1-1 is that D1 = 1 mm, D2 = 0.6 mm, D5 = 5 mm, and gap 1a = 6.6 mm.
[0107] Examples 1-4
[0108] The difference from Example 1-1 is that D1 = 1.5mm, D2 = 0.6mm, D5 = 5mm, and gap 1a = 7.1mm.
[0109] Examples 1-5
[0110] The difference from Example 1-1 is that D1 = 2mm, D2 = 0.6mm, D5 = 5mm, and gap 1a = 7.6mm.
[0111] Examples 1-6
[0112] The difference from Example 1-1 is that D1 = 3mm, D2 = 0.6mm, D5 = 5mm, and gap 1a = 8.6mm.
[0113] Comparative Example 1-1
[0114] The difference from Example 1-1 is that D1 = 0.3 mm, D2 = 0.6 mm, D5 = 5 mm, and gap 1a = 5.9 mm.
[0115] Comparative Examples 1-2
[0116] The difference from Example 1-1 is that D1 = 3.5mm, D2 = 0.6mm, D5 = 5mm, and gap 1a = 9.1mm.
[0117] Example 2-1
[0118] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 0.2 mm, D5 = 5 mm, and gap 1a = 6 mm.
[0119] Example 2-2
[0120] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 0.3 mm, D5 = 5 mm, and gap 1a = 6.1 mm.
[0121] Example 2-3
[0122] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 0.6 mm, D5 = 5 mm, and gap 1a = 6.4 mm.
[0123] Examples 2-4
[0124] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 1 mm, D5 = 5 mm, and gap 1a = 6.8 mm.
[0125] Examples 2-5
[0126] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 1.8 mm, D5 = 5 mm, and gap 1a = 7.6 mm.
[0127] Examples 2-6
[0128] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 2.5 mm, D5 = 5 mm, and gap 1a = 8.3 mm.
[0129] Examples 2-7
[0130] The difference from Example 1-1 is that D1 = 0.8 mm, D2 = 3 mm, D5 = 5 mm, and gap 1a = 8.8 mm.
[0131] Comparative Example 1
[0132] The difference from Example 1-1 is that D1 = 0.3 mm, D2 = 0.6 mm, D5 = 5 mm, and gap 1a = 5.9 mm.
[0133] Comparative Example 2
[0134] The difference from Example 1-1 is that D1 = 3.5mm, D2 = 0.6mm, D5 = 5mm, and gap 1a = 9.1mm.
[0135] Table 1
[0136] Comparing any of Examples 1-1 to 1-6 with Comparative Example 1 or Comparative Example 2, it can be seen that D1 satisfies: 0.5mm≤D1≤3mm. Limiting D1 to this size range can reduce the interference between the overflow block and the second sealing part, thereby improving the safety and reliability of the secondary battery; it can also reduce size redundancy, thereby improving the energy density of the secondary battery.
[0137] Furthermore, 0.8mm ≤ D1 ≤ 2mm. With D1 controlled within this size range, the secondary battery exhibits superior safety and reliability while maintaining reasonable size redundancy, thus further improving its energy density. This can also be illustrated by subsequent test results.
[0138] Furthermore, 0.8mm≤D1≤1mm. With D1 controlled within this size range, the safety and reliability of the secondary battery are optimal, and its size redundancy control is more reasonable, thus maximizing the energy density improvement of the secondary battery.
[0139] Comparing any of Examples 2-1 to 2-7 with Comparative Example 1, it can be seen that when D1 is within the aforementioned value range, and D2 takes any value, the drop + high temperature + high humidity pass rate of the secondary battery is improved compared to the secondary battery in Comparative Example 1.
[0140] Comparing any of Examples 2-2 to 2-6 with Examples 2-1 or 2-7, it can be seen that 0.3mm ≤ D2 ≤ 2.5mm. Adjusting D2 within this size range can reduce the interference between the overflow adhesive block and the first sealing part, and minimize the energy density loss of the secondary battery.
[0141] Furthermore, 0.6mm≤D1≤1.8mm. With D1 controlled within this size range, the safety and reliability of the secondary battery are better, and its size redundancy control is more reasonable, resulting in less energy density loss in the secondary battery.
[0142] It can be seen that the secondary battery involved in the embodiments of this application can improve the interference between the overflow adhesive block and its adjacent and folded side seal, thereby improving the safety and reliability of the secondary battery.
[0143] 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.
[0144] 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 tabs, wherein the packaging bag comprises a main body, a first sealing portion, and a second sealing portion, the electrode assembly is disposed within the main body, the main body comprises a first wall and a second wall, the first wall being connected to the second wall, the first sealing portion being connected to the first wall, and the second sealing portion being connected to the second wall, characterized in that, Along the second direction, a gap is formed between the second sealing portion and the first sealing portion; The electrode tab includes an electrode adhesive, which includes an electrode adhesive body and an extension portion integrally connected to the electrode adhesive body. The electrode adhesive body is adhered to the packaging bag. The extension portion extends beyond the packaging bag in a third direction. When viewed in the third direction, the projection of the extension portion falls within the gap. The third direction, the second direction, and the thickness direction of the electrode assembly are perpendicular to each other. Along the second direction, the distance D1 between the extended portion and the second sealing portion satisfies: 0.5mm≤D1≤3mm.
2. The secondary battery according to claim 1, characterized in that, 0.8mm≤D1≤2mm.
3. The secondary battery according to claim 2, characterized in that, 0.8mm≤D1≤1mm.
4. The secondary battery according to claim 1, characterized in that, The first sealing part is bent toward a first direction, and the second sealing part is bent toward the first direction, where the first direction is the thickness direction of the electrode assembly.
5. The secondary battery according to claims 1-4, characterized in that, The main body includes a third wall, which is connected to the first wall and the second wall respectively; The packaging bag includes a third sealing part, which is connected to the third wall; The tab adhesive body is bonded to the third sealing portion, and the protruding portion extends beyond the edge of the third sealing portion away from the third wall in a third direction.
6. The secondary battery according to claim 5, characterized in that, The third wall includes a first connecting wall and a second connecting wall. The first connecting wall is integrally connected to the first wall and the second connecting wall, respectively. The first connecting wall is recessed in the second direction relative to the second wall. The second wall is integrally connected to the first connecting wall through the second connecting wall, and the second connecting wall is recessed in the third direction relative to the first wall. The third sealing part is integrally connected to the first connecting wall, the second connecting wall, the second sealing part, and the first sealing part.
7. The secondary battery according to claim 6, characterized in that, Along the third direction, the edge of the third sealing portion away from the third wall does not extend beyond the first wall.
8. The secondary battery according to claim 6, characterized in that, The edge of the first sealing portion near the electrode extends beyond the first connecting wall along the second direction.
9. The secondary battery according to claim 6, characterized in that, Along the second direction, the distance D2 between the extended portion and the first sealing portion satisfies: 0.3mm≤D2≤2.5mm.
10. The secondary battery according to claim 9, characterized in that, 0.6mm≤D2≤1.8mm.
11. The secondary battery according to claim 9, characterized in that, D1≥D2.
12. The secondary battery according to any one of claims 11, 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 electrode tab is electrically connected to the main body of the electrode assembly; The electrode assembly includes multiple electrodes and multiple insulating films; The electrode includes an electrode body and a first protrusion integrally connected to the electrode body; The isolation membrane includes an isolation membrane body and a second protrusion integrally connected to the isolation membrane body; The electrode assembly body is formed by stacking the plurality of electrode bodies and the plurality of insulating membrane bodies, and the protrusion is formed by stacking the first protrusion and the second protrusion.
13. The secondary battery according to claim 12, characterized in that, An empty foil area is provided at one corner of the electrode, and a notch is provided at the other corner of the electrode. The notch is used to avoid the empty foil area of the adjacent electrode. Along the second direction, the first protrusion is disposed between the notch and the empty foil area.
14. The secondary battery according to any one of claims 1-4, characterized in that, The electrode tab includes a metal strip inside the main body, one end of the metal strip is electrically connected to the electrode assembly, and the other end of the metal strip extends out of the packaging bag through the gap; The secondary battery satisfies at least one of the following conditions. (1) Along the second direction, the distance D3 between one edge of the metal strip and the protruding part satisfies: 0.8mm≤D3≤2.5mm; (2) Along the second direction, the distance D4 between the other edge of the metal strip and the extended portion satisfies: 0.8mm≤D4≤2.5mm.
15. An electrical appliance, characterized in that, Includes the secondary battery as described in any one of claims 1-14.