Electrochemical device and preparation method therefor, and electronic device

Abstract

An electrochemical device and a preparation method therefor, and an electronic device. The electrochemical device comprises a pouch, an electrode assembly and a conductive plate. The pouch comprises a main body portion and a sealing portion, and the electrode assembly is provided in the main body portion. The main body portion comprises a first end wall and a second end wall arranged opposite each other, and a first side wall and a second side wall arranged opposite each other. The sealing portion comprises a first sealing portion and a second sealing portion, wherein the first sealing portion is connected to the first end wall; the conductive plate extends out of the pouch from the first sealing portion; the second sealing portion is connected to the first side wall and disposed opposite the first side wall; the first sealing portion and the second sealing portion intersect within a connection region; the connection region is folded N times towards the first end wall to form a folded-corner structure; the folded-corner structure comprises N folded-corner portions; an N-th folded-corner portion is formed by folding the connection region for an N-th time towards the first end wall along an N-th folded-corner line; and the included angle between the N-th folded-corner line and the direction in which the conductive plate extends out of the pouch is α, where 15°≤α≤75°.

Description

Electrochemical devices and their preparation methods, electronic devices Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to an electrochemical device and its preparation method, as well as an electronic device having the electrochemical device. Background Technology

[0002] Electrochemical devices (such as batteries) are widely used in electronic mobile devices, power tools, and electric vehicles. During the fabrication of electrochemical devices, the upper and lower encapsulation films are heat-sealed using a sealing head to form a seal, thereby encapsulating the electrode components within the housing. However, this sealing process can affect the energy density of the electrochemical device.

[0003] Summary of the Invention

[0004] Given the shortcomings of existing technologies, it is necessary to propose an electrochemical device that can improve energy density and its preparation method.

[0005] Additionally, it is necessary to provide an electronic device having the electrochemical device.

[0006] This application provides an electrochemical device, including a packaging bag, an electrode assembly, and a conductive plate. The packaging bag includes a main body and a sealing portion, with the electrode assembly disposed within the main body. The conductive plate is electrically connected to the electrode assembly. The conductive plate extends out of the packaging bag along a first direction, the thickness direction of the electrode assembly is a second direction, and a direction perpendicular to the first and second directions is a third direction. The main body includes a first end wall and a second end wall disposed opposite each other in the first direction, and also includes a first side wall and a second side wall disposed opposite each other in the third direction. The sealing portion includes a first sealing portion and a second sealing portion, the first sealing portion being connected to the first end wall, and the conductive plate extending out of the packaging bag from the first sealing portion. The second sealing portion is connected to the first side wall, and the second sealing portion and the first side wall are disposed opposite each other in the third direction. The first sealing portion and the second sealing portion intersect within a connection area. The connection area is folded N times toward the first end wall to form a folded structure, where N is an integer greater than or equal to 2. The folded structure includes N folded portions, the Nth folded portion being formed by folding the connection area along the Nth fold line toward the first end wall for the Nth time. The angle between the Nth bend line and the first direction is α, where 15°≤α≤75°.

[0007] This application reduces the space occupied by the connection area by folding it N times towards the first end wall, and sets an angle α between the fold line of the last fold and the first direction. This not only reduces the size of the first sealing part in the third direction and the size of the second sealing part in the first direction, thereby reducing the space occupied by the connection area and increasing the energy density of the electrochemical device, but also allows the shape of the electrochemical device to better match the actual shape of the battery compartment of the electronic device, reducing the impact of a battery compartment with a specific shape on the energy density of the electrochemical device. Furthermore, by setting a lower limit for the angle α, the energy density can be increased while making it easy to implement multiple folds, thereby improving production efficiency. By setting an upper limit for the angle α, the risk of the conductive plate being bent during the Nth fold is reduced. This not only facilitates the electrical connection between the conductive plate and external components, but also reduces the risk of the electrochemical device failing due to the conductive plate breaking after bending. It also reduces the risk of electrochemical corrosion caused by the bent conductive plate puncturing the packaging bag and the electrolyte in the electrolyte coming into contact with the metal layer of the packaging bag, thus improving the reliability of the electrochemical device.

[0008] Based on the first aspect, in some possible implementations, the packaging bag includes a first encapsulation film and a second encapsulation film disposed opposite each other in a second direction. The first encapsulation film includes a first encapsulation layer, and the second encapsulation film includes a second encapsulation layer. The first sealing portion includes a sealing region and a transition region, the transition region connecting the sealing region and the main body portion respectively in the first direction. The first encapsulation layer and the second encapsulation layer are bonded together in the sealing region, and the first encapsulation layer and the second encapsulation layer are separated in the transition region. The width of the sealing region in the first direction is 1.0 mm to 2.0 mm, and the width of the transition region in the first direction is 0.3 mm to 1.0 mm. Therefore, the encapsulation strength of the first sealing portion can be improved while reducing the waste of energy density in the electrochemical device.

[0009] Based on the first aspect, in some possible implementations, N=2. The folded structure includes a first folded portion and a second folded portion. The first folded portion is formed by folding the connecting area along the first fold line toward the first end wall for the first time. The second folded portion is formed by folding the connecting area along the second fold line toward the first end wall for the second time. Viewed from the second direction, the first folded portion and the second folded portion overlap. Therefore, while increasing the energy density of the electrochemical device, the risk of the second folded portion opening relative to the first folded portion can be reduced.

[0010] Based on the first aspect, in some possible implementations, the first fold line and the second fold line intersect at a first intersection point. Viewed from the second direction, the first intersection point overlaps with the transition region. This overlap between the first intersection point and the transition region allows the second fold formed by the second fold to have a larger area, thereby further reducing the dimensions of the first sealing portion in the third direction and the second sealing portion in the first direction, thus increasing the energy density of the electrochemical device.

[0011] Based on the first aspect, in some possible implementations, 45°≤α≤75°. The first fold line and the second fold line intersect at a first intersection point. Viewed from the second direction, the first intersection point overlaps with the sealing area. By setting the first intersection point to overlap with the sealing area and shifting the position of the first intersection point along the first direction, stress can be dispersed, thereby reducing the risk of the packaging bag breaking at the first intersection point. Moreover, even if the packaging bag breaks at the first intersection point, the position of the first intersection point can isolate the broken area from the electrolyte, thus reducing the risk of electrochemical corrosion or leakage at the first intersection point. This allows the electrochemical device to achieve both high energy density and reliability.

[0012] Based on the first aspect, in some possible implementations, the first fold line includes a first segment and a second segment connected together. The first segment is disposed on the first fold portion. The second segment and the second fold line are disposed on the second fold portion. Therefore, the risk of packaging bag damage caused by the first and second folds intersecting at the same point can be reduced, and production efficiency can be easily improved.

[0013] Based on the first aspect, in some possible implementations, viewed from a third direction, the second sealing portion includes a first edge and a second edge disposed opposite to each other in a second direction, the second edge connecting to the first sidewall. The first segment intersects the first edge at a second intersection point. Viewed from the second direction, the first intersection point and the second intersection point do not coincide. Therefore, the risk of the packaging bag breaking at the overlapping intersection point after a second fold can be reduced, and it is also easier to improve production efficiency.

[0014] Based on the first aspect, in some possible implementations, viewed from the second direction, the angle between the first segment and the first direction is β, where 0° < β ≤ 15°. Therefore, this facilitates subsequent folding and improves the effectiveness of subsequent folding, while also reducing the risk of the folded area formed during the first fold being too close to the conductive plate, or even the conductive plate being bent during the first fold.

[0015] Based on the first aspect, in some possible implementations, the first sealing portion includes a first region and the aforementioned connecting region interconnected. The first region connects to a portion of the first end wall. The connecting region includes a first section and a second section interconnected. The second section connects to another portion of the first end wall and the first region, respectively. The first sealing portion and the second sealing portion intersect at the first section. The first folded portion includes a portion of the second section. Therefore, after the first fold, the dimensions of the first sealing portion in the third direction and the dimensions of the second sealing portion in the first direction are further reduced, thereby facilitating a further increase in the energy density of the electrochemical device.

[0016] Based on the first aspect, in some possible implementations, the sealing area includes a third edge and a fourth edge disposed opposite each other in the first direction, with the third edge being closer to the transition area than the fourth edge. In the first direction, the distance between the first intersection point and the third edge within the first area is L, where L > 0.3 mm. Therefore, even if the packaging bag is damaged at the first intersection point, the risk of electrochemical corrosion or leakage can be further reduced, improving the reliability of the electrochemical device.

[0017] Based on the first aspect, in some possible implementations, the electrochemical device further includes a first adhesive member that adhesively bonds the first bend and the second bend. Therefore, the risk of the second bend opening relative to the first bend can be reduced.

[0018] Based on the first aspect, in some possible implementations, N=3. The folded structure includes a first folded portion, a second folded portion, and a third folded portion. The first folded portion is formed by folding the connecting area along the first fold line toward the first end wall for the first time. The second folded portion is formed by folding the connecting area along the second fold line toward the first end wall for the second time. The third folded portion is formed by folding the connecting area along the third fold line toward the first end wall for the third time. Viewed from the second direction, the first folded portion, the second folded portion, and the third folded portion overlap in pairs. Therefore, the energy density of the electrochemical device can be further improved.

[0019] Based on the first aspect, in some possible implementations, the first fold line includes a first segment and a second segment connected together, with the first segment positioned on the first fold. The second fold line includes a third segment and a fourth segment connected together, with the second and third segments positioned on the second fold, and the fourth segment and the third fold line positioned on the third fold. Therefore, the risk of packaging bag damage caused by the second and third folds occurring at the same intersection point can be reduced.

[0020] Based on the first aspect, in some possible implementations, the third fold line intersects the second fold line at a third intersection point. In the first direction, the distance between the third intersection point and the first end wall is greater than the distance between the first intersection point and the first end wall. Viewed from the second direction, the third intersection point overlaps with the sealing area. Considering that there are four layers of sealing film at the third intersection point, the packaging bag still faces a risk of breakage at this point after the third fold. Therefore, by setting the overlap between the third intersection point and the sealing area, the risk of electrochemical corrosion or leakage can be reduced after the packaging bag breaks at the third intersection point, thereby improving the reliability of the electrochemical device.

[0021] Based on the first aspect, in some possible implementations, the first fold line includes a first segment and a second segment connected together. The first segment includes a first sub-segment and a second sub-segment connected together, and the second sub-segment connects to the second fold line. The first sub-segment is located on the first fold. The second sub-segment, the second fold line, and the third fold line are located on the third fold. Therefore, the risk of packaging bag damage caused by the second and third folds occurring at the same intersection point can be reduced.

[0022] Based on the first aspect, in some possible implementations, the third fold line intersects the first segment at a third intersection point. In the first direction, the third intersection point is located between the first intersection point and the first end wall. Viewed from the second direction, the third intersection point overlaps with the sealing area or transition area. Therefore, the third fold formed by the third fold can have a larger area, thereby further reducing the size of the first sealing portion in the third direction and the size of the second sealing portion in the first direction, increasing the energy density of the electrochemical device. Furthermore, when the third intersection point overlaps with the sealing area, even if the packaging bag breaks at the third intersection point, the risk of electrochemical corrosion or leakage can be reduced, improving the reliability of the electrochemical device.

[0023] Based on the first aspect, in some possible implementations, the electrochemical device further includes a circuit board electrically connected to a conductive plate. The first sealing portion and the first end wall together form an accommodating space, within which the circuit board is disposed. Therefore, the impact of the circuit board on the energy density of the electrochemical device can be reduced.

[0024] A second aspect of this application provides an electronic device including a battery compartment. The electronic device also includes the aforementioned electrochemical device, which is disposed within the battery compartment. This application improves the energy density of the electrochemical device and reduces the impact of a battery compartment with a specific shape on the energy density of the electrochemical device by folding the connection area toward the first end wall N times and setting an angle α between the fold line of the last fold and the first direction. Furthermore, by setting a lower limit for the angle α, the energy density can be increased while facilitating multiple folds, thereby improving production efficiency. By setting an upper limit for the angle α, the risk of the conductive plate being bent during the Nth fold is reduced, thereby reducing the risk of the conductive plate breaking after bending, leading to failure of the electrochemical device. It also reduces the risk of the bent conductive plate puncturing the packaging bag, causing the electrolyte in the electrolyte solution to contact the metal layer of the packaging bag and triggering electrochemical corrosion, thus improving the reliability of the electrochemical device.

[0025] Based on the second aspect, in some possible implementations, the battery compartment is at least partially curved.

[0026] A third aspect of this application provides a method for preparing the aforementioned electrochemical device, comprising the following steps: preparing an electrode assembly, wherein the electrode assembly is electrically connected to a conductive plate; placing the electrode assembly with the conductive plate into a packaging bag and sealing it to form a sealing portion, wherein the conductive plate extends out of the packaging bag from the first sealing portion; folding the sealing portion so that it is positioned opposite to the first sidewall in a third direction to form a second sealing portion; and folding the connection area toward the first endwall N times to form a folded structure. This application, by folding the connection area toward the first endwall N times and setting an angle α between the fold line of the last fold and the first direction, not only reduces the size of the first sealing portion in the third direction and the size of the second sealing portion in the first direction, but also reduces the space occupied by the connection area, increases the energy density of the electrochemical device, and reduces the impact of a battery compartment with a specific shape on the energy density of the electrochemical device. Furthermore, by setting a lower limit for the included angle α, the energy density can be increased while facilitating multiple folds, thereby improving production efficiency. By setting an upper limit for the included angle α, the risk of the conductive plate being bent during the Nth fold is reduced, thus reducing the risk of the electrochemical device failing due to the conductive plate breaking after bending. It also reduces the risk of electrochemical corrosion caused by the bent conductive plate puncturing the packaging bag, leading to contact between the electrolyte in the electrolyte solution and the metal layer of the packaging bag, thereby improving the reliability of the electrochemical device. Attached Figure Description

[0027] Figure 1 is a schematic diagram of the structure of the electrochemical device provided in one embodiment of this application when viewed along the second direction.

[0028] Figure 2 is a partial enlarged view of point II in some embodiments of the electrochemical device shown in Figure 1.

[0029] Figure 3 is a partial enlarged view of point II in some other embodiments of the electrochemical device shown in Figure 1.

[0030] Figure 4 is a three-dimensional structural diagram of the electrochemical device shown in Figure 1 before encapsulation.

[0031] Figure 5 is a cross-sectional view of the electrochemical device shown in Figure 1 along the cutting line VV.

[0032] Figure 6 is a cross-sectional view of the first encapsulation membrane of the electrochemical device shown in Figure 1.

[0033] Figure 7 is a schematic diagram of the electrochemical device shown in Figure 1 before the packaging bag is folded.

[0034] Figure 8 is a schematic diagram of the structure of the packaging bag shown in Figure 7 after the sealing part is folded to form the second sealing part.

[0035] Figure 9 is a front view of the connecting area of ​​the packaging bag shown in Figure 8 after the first fold.

[0036] Figure 10 is a partial enlarged view of the electrochemical device shown in Figure 9 at point IX.

[0037] Figure 11 is a schematic diagram of the structure of an electrochemical device provided in another embodiment of this application when viewed in the second direction.

[0038] Figure 12 is a schematic diagram of the structure of an electrochemical device of some other embodiments when viewed in the second direction.

[0039] Figure 13 is a schematic diagram of the structure of an electronic device provided in another embodiment of this application when viewed in a second direction.

[0040] Figure 14 is a schematic diagram of the structure of an electronic device provided in one embodiment of this application.

[0041] Figure 15 is a schematic diagram of the internal structure of the electronic device shown in Figure 14.

[0042] Figure 16 is a flowchart of a method for preparing an electrochemical device according to an embodiment of this application.

[0043] Explanation of main component symbols

[0044] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0045] The technical solutions in the embodiments of this application are described clearly and in detail below. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit this application.

[0046] The embodiments of this application will be described in detail below. However, this application may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided to provide a thorough and detailed understanding of this application to those skilled in the art.

[0047] Additionally, for brevity and clarity, the dimensions or thicknesses of various components and layers may be enlarged in the accompanying drawings. Throughout the text, the same numerical values ​​refer to the same elements. As used herein, the terms "and / or" and "and / or" include any and all combinations of one or more of the associated enumerated items. Furthermore, it should be understood that when element A is referred to as "connecting" element B, element A may be directly connected to element B, or there may be an intermediate element C and element A and element B may be indirectly connected to each other.

[0048] Furthermore, when describing the implementation of this application, the word "may" refers to "one or more implementations of this application".

[0049] The technical terms used herein are for the purpose of describing particular embodiments and are not intended to limit this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. It should be further understood that the term "comprising," as used in this specification, means the presence of the described features, values, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, values, steps, operations, elements, components, and / or combinations thereof.

[0050] Spatial terms, such as "above," may be used herein for convenience in describing the relationship between one element or feature and another element (or feature) or feature (or feature) illustrated in the figures. It should be understood that, in addition to the directions depicted in the figures, spatial terms are intended to include different orientations of the device or apparatus during use or operation. For example, if the device in the figure is flipped, an element described as "above" or "on" other elements or features would be oriented "below" or "under" other elements or features. Therefore, the exemplary term "above" can include both above and below orientations. It should be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or portion from another element, component, region, layer, or portion. Therefore, a first element, component, region, layer, or portion discussed below may be referred to as a second element, component, region, layer, or portion without departing from the teachings of the exemplary embodiments.

[0051] Referring to Figures 1 to 5, one embodiment of this application provides an electrochemical device 100, including a packaging bag 10, an electrode assembly 20, and a conductive plate. The electrode assembly 20 is located inside the packaging bag 10. The conductive plate may include a first conductive plate 30 and a second conductive plate 40, both of which are electrically connected to the electrode assembly 20 and extend out of the packaging bag 10. The first conductive plate 30 and the second conductive plate 40 can be connected to external components (not shown). As shown in Figures 4 and 5, in some embodiments, the electrode assembly 20 can be a wound structure. The electrode assembly 20 includes a negative electrode 21, a positive electrode 22, and a separator 23. The negative electrode 21, the separator 23, and the positive electrode 22 are sequentially stacked and wound. The first conductive plate 30 is electrically connected to the negative electrode 21, and the second conductive plate 40 is electrically connected to the positive electrode 22. In other embodiments, the electrode assembly 20 can also be a stacked structure, i.e., the negative electrode 21, the separator 23, and the positive electrode 22 are sequentially stacked.

[0052] As shown in Figures 1 and 5, the packaging bag 10 includes a main body 11 and a sealing part 12. The electrode assembly 20 is disposed within the main body 11, and the sealing part 12 is connected to the main body 11. The direction in which the first conductive plate 30 or the second conductive plate 40 extends out of the packaging bag 10 is defined as the first direction X, the thickness direction of the electrode assembly 20 is defined as the second direction Y, and the direction perpendicular to the first direction X and the second direction Y is defined as the third direction Z. The third direction Z can also be the direction from the first conductive plate 30 to the second conductive plate 40.

[0053] Figure 4 is a schematic diagram of the electrochemical device 100 before encapsulation. The packaging bag 10 includes a first encapsulation film 10A and a second encapsulation film 10B disposed opposite each other in the second direction Y, and the packaging bag 10 is formed by encapsulating the first encapsulation film 10A and the second encapsulation film 10B. In some embodiments, the first encapsulation film 10A and the second encapsulation film 10B can be obtained by folding the same encapsulation film, and the folding points of the first encapsulation film 10A and the second encapsulation film 10B correspond to the tails of the electrode assembly 20 away from the first conductive plate 30 and the second conductive plate 40. The first encapsulation film 10A includes a first film region 10A1 and a second film region 10A2 that are interconnected. The three sides of the second film region 10A2 are surrounded by the first film region 10A1. The second film region 10A2 of the first encapsulation film 10A has a recess S1. The second membrane region 10A2 and the fourth membrane region 10B2 together form the main body 11 for housing the electrode assembly 20. When preparing the packaging bag 10, a certain temperature and pressure can be applied simultaneously to the first membrane region 10A1 and the third membrane region 10B1 using the sealing head of the packaging equipment. The first membrane region 10A1 and the third membrane region 10B1 are connected to form a sealing portion 12, thereby sealing the main body 11 for housing the electrode assembly 20 and reducing the risk of leakage. In this application, the sealing portion 12 includes a first sealing portion 121 and a second sealing portion 122. The first sealing portion 121 seals the main body 11 in the first direction X, and the second sealing portion 122 seals the main body 11 in the second direction Y.

[0054] Both the first encapsulation film 10A and the second encapsulation film 10B are made of multilayer sheets. As shown in FIG6, the first encapsulation film 10A may include a first protective layer 101, a first metal layer 102, and a first encapsulation layer 103 stacked sequentially. Compared to the first protective layer 101, the first encapsulation layer 103 is closer to the electrode assembly 20. The first protective layer 101 may be made of a polymer resin, which can be used to protect the first metal layer 102, reduce the risk of damage to the first metal layer 102 due to external forces, and delay the air penetration from the external environment, maintaining the internal environment of the electrochemical device 100 in a normal operating environment. In some embodiments, the material of the first protective layer 101 may be selected from at least one of polyethylene terephthalate, polybutylene terephthalate, polyvinylidene fluoride, polytetrafluoroethylene, polypropylene, polyamide, and polyimide. The first metal layer 102 can be used to delay the penetration of moisture from the external environment and reduce damage to the electrode assembly 20 caused by external forces. In some embodiments, the first metal layer 102 may be an aluminum foil layer or a steel foil layer. The first encapsulation layer 103 has the property of melting upon heating, which can be used for encapsulation and can reduce the risk of the multilayer sheet being dissolved or swollen by the organic solvent in the electrolyte. The first encapsulation layer 103 can also be used to reduce the risk of corrosion of the metal layer due to contact between the electrolyte in the electrolyte and the first metal layer 102. In some embodiments, the first encapsulation layer 103 includes a polymer material, which can be selected from at least one polymer material selected from polypropylene, propylene copolymer, polyethylene, and polymethyl methacrylate. The second encapsulation film 10B may include a second protective layer (not shown), a second metal layer (not shown), and a second encapsulation layer (not shown) stacked sequentially. It is understood that when the first encapsulation film 10A and the second encapsulation film 10B can be obtained by folding a single encapsulation film, the materials of the second protective layer, the second metal layer, and the second encapsulation layer are the same as the materials of the first protective layer 101, the first metal layer 102, and the first encapsulation layer 103, respectively, and will not be described again here. During encapsulation, the first encapsulation layer 103 and the second encapsulation layer are melted together and bonded together to form a first sealing portion 121 and a second sealing portion 122.

[0055] As shown in Figure 2, the first sealing portion 121 includes a sealing region 1212 and a transition region 1213. The transition region 1213 connects the sealing region 1212 and the main body 11 in the first direction X. The first encapsulation layer 103 and the second encapsulation layer are bonded together in the sealing region 1212, while the first encapsulation layer 103 and the second encapsulation layer are separated in the transition region 1213. In the second direction Y, the thickness of the transition region 1213 can be less than the thickness of the main body 11 and greater than the thickness of the sealing region 1212. The width W1 of the sealing region 1212 in the first direction X is 1.0 mm to 2.0 mm, and the width W2 of the transition region 1213 in the first direction X is 0.3 mm to 1.0 mm. The widths W1 and W2 can be adjusted by the width of the sealing head of the encapsulation device. In this way, the encapsulation strength of the first sealing portion 121 can be improved while reducing the waste of energy density in the electrochemical device 100.

[0056] As shown in Figure 1, the main body 11 includes a first end wall 111 and a second end wall 112 disposed opposite to each other in a first direction X. Viewed from the second direction Y, a transition region 1213 is in contact with the first end wall 111. The main body 11 also includes a first side wall 113 and a second side wall 114 disposed opposite to each other in a third direction Z. Viewed from the second direction Y, the surface of the first end wall 111 extends in both the second direction Y and the third direction Z, and the surface of the second end wall 112 extends in both the second direction Y and the third direction Z. The first side wall 113 connects the first end wall 111 and the second end wall 112, and the second side wall 114 connects the first end wall 111 and the second end wall 112. The surface of the first side wall 113 extends in both the first direction X and the second direction Y, and the surface of the second side wall 114 extends in both the first direction X and the second direction Y.

[0057] The first sealing portion 12 is connected to the first end wall 111, and the first conductive plate 30 and the second conductive plate 40 extend out of the packaging bag 10 from the first sealing portion 121. The second sealing portion 122 is connected to the first side wall 113, and the second sealing portion 122 and the first side wall 113 are arranged opposite each other in the third direction Z. In some embodiments, the second sealing portion 122 is a single-fold structure formed after one fold. That is, the sealing portion 12 connected to the first side wall 113 is arranged opposite to the first side wall 113 in the third direction Z after one fold, forming the second sealing portion 122. Specifically, FIG7 shows the structure of the second sealing portion 122 before folding, at which time the plane of the second sealing portion 122 extends in the first direction X and the third direction Z. FIG8 shows the structure of the second sealing portion 122 after folding. After one fold, the second sealing portion 122 is arranged opposite to the first side wall 113 in the third direction Z, thereby reducing the size of the electrochemical device 100 in the third direction Z, improving space utilization and energy density. In some embodiments, to reduce the risk of the second sealing portion 122 opening relative to the first sidewall 113, the second sealing portion 122 and the first sidewall 113 can be bonded together. Specifically, an adhesive (not shown) can be provided between the second sealing portion 122 and the first sidewall 113. The adhesive can be double-sided tape or hot melt adhesive. The material of the adhesive layer in the double-sided tape can be selected from one or more of acrylate, polyurethane, rubber, and silicone. The hot melt adhesive can be selected from one or more of polyolefin hot melt adhesives, polyurethane hot melt adhesives, ethylene and its copolymers hot melt adhesives, polyester hot melt adhesives, polyamide hot melt adhesives, styrene and its block copolymers hot melt adhesives; this application is not limited to any of these.

[0058] As shown in Figures 1 and 8, in some embodiments, the sealing portion 12 may further include a third sealing portion 123. The third sealing portion 123 is connected to the second sidewall 114, and the third sealing portion 123 and the second sidewall 114 are disposed opposite to each other in the third direction Z. In some embodiments, the third sealing portion 123 is also a single-fold structure formed by one fold, that is, the sealing portion 12 connected to the second sidewall 114 is folded once and disposed opposite to the second sidewall 114 to form the third sealing portion 123, thereby further reducing the size of the electrochemical device 100 in the third direction Z, and improving space utilization and energy density.

[0059] As shown in Figure 7, the first sealing portion 121 includes a connecting region 1200 and a first region 1211 sequentially arranged in the third direction Z. The first region 1211 connects to a portion of the first end wall 111. The first conductive plate 30 and the second conductive plate 40 both extend out of the packaging bag 10 from the first region 1211. The connecting region 1200 includes a first partition 1201 and a second partition 1202, which connect to another portion of the first end wall 111 and the first region 1211, respectively. The second sealing portion 122 includes a second region 1221 and the aforementioned first partition 1201 sequentially arranged in the first direction X. The second region 1221 connects to the first side wall 113. That is, the first sealing portion 121 and the second sealing portion 122 intersect at the first partition 1201 within the connecting region 1200. In some embodiments, the connecting region 1200 may further include a third partition 1203, which connects to a portion of the first side wall 113, and the second region 1221 connects to another portion of the first side wall 113.

[0060] As shown in Figures 7 to 10 and Figure 2, the connecting area 1200 is folded N times toward the first end wall 111 to form a folded structure 70, where N is an integer greater than or equal to 2. Specifically, the folded structure 70 is formed after the second sealing part 122 is formed (i.e., after folding the portion of the sealing part 12 connecting the first side wall 113 to be positioned opposite the first side wall 113 to form the second sealing part 122), and then folding the connecting area 1200 toward the first end wall 111 N times. Specifically, Figure 7 shows the structure after the second sealing part 122 is formed. During the formation of the second sealing part 122, the second partition 1202 may not be folded. After the second sealing part 122 is formed, the connecting area 1200 is folded N times toward the first end wall 111 to form the folded structure 70. As shown in Figure 2, after N folds, the angled structure 70 includes N angled portions, wherein the Nth angled portion is formed by folding the connecting area 1200 along the Nth angled line toward the first end wall 111 for the Nth time. The angle between the Nth angled line and the first direction X is α, where 15°≤α≤75°.

[0061] In some embodiments, N=2, meaning the connecting area 1200 is folded twice toward the first end wall 111 to form a folded structure 70. Specifically, as shown in Figures 9 and 10, the connecting area 1200 is first folded around the first fold line 73 (shown in Figure 10) toward the first end wall 111 to form a first folded portion 71. Then, as shown in Figures 10 and 2, the connecting area 1200 is folded a second time around the second fold line 74 toward the first end wall 111 to form a second folded portion 72 as shown in Figure 2. At this time, the angle between the second fold line 74 and the first direction X is the aforementioned angle α. Viewed from the second direction Y, the first folded portion 71 and the second folded portion 72 overlap.

[0062] As shown in Figures 10 and 2, in some embodiments, during the second fold to form the second corner portion 72, a portion of the second partition 1202 in the connecting area 1200 is folded toward the first end wall 111, such that the second corner portion 72 formed in Figure 2 includes a portion of the second partition 1202. At this time, the second fold line 74 intersects the edge 1202A of the second partition 1202 at the intersection point 741. Therefore, compared to folding the connecting area 1200 once, two folds can help reduce the size of the first sealing portion 121 in the third direction Z. Moreover, the size of the included angle α during the second fold can be changed according to actual needs, thus allowing the shape of the electrochemical device 100 to be adaptively adjusted according to the actual shape of the battery compartment of the electronic device. In some embodiments, in addition to the second corner portion 72 including a portion of the second partition 1202, the first corner portion 71 also includes a portion of the second partition 1202. That is, during the first fold to form the first corner portion 71, a portion of the second partition 1202 in the connecting area 1200 is folded toward the first end wall 111. Therefore, after the first fold, the size of the first sealing part 121 in the third direction Z can be reduced, which is beneficial to further improve the energy density. At this time, as shown in FIG9, when viewed from the second direction Y, the intersection 741 of the second fold line 74 and the edge 1202A of the second partition 1202 is located in the second partition 1202.

[0063] As shown in Figure 10, the folding area that folds towards the first end wall 111 for the first time is defined as A. Folding area A is divided into a fourth section A1 and a fifth section A2. Referring to Figure 2, the fourth section A1 will continue to form part of the second folded portion 72 after the second fold. Therefore, the aforementioned first folded portion 71 refers to the area that folds towards the first end wall 111 for the first time but is not subsequently folded a second time. That is, the first folded portion 71 refers to the fifth section A2.

[0064] This application reduces the space occupied by the connection area 1200 by folding the connection area 1200 toward the first end wall 111 N times, and sets the angle α between the fold line of the last fold and the first direction X. This not only reduces the size of the first sealing part 121 in the third direction Z and the size of the second sealing part 122 in the first direction X, thereby reducing the space occupied by the connection area 1200 and increasing the energy density of the electrochemical device 100, but also allows the shape of the electrochemical device 100 to better match the actual shape of the battery compartment of the electronic device, reducing the impact of the battery compartment of a specific shape on the energy density of the electrochemical device 100. Furthermore, by setting a lower limit for the included angle α, the energy density can be increased while making it easy to implement multiple folds, thereby improving production efficiency. By setting an upper limit for the included angle α, the risk of the conductive plate being bent during the Nth fold is reduced, thereby reducing the risk of the electrochemical device 100 failing due to the conductive plate breaking after bending. It also reduces the risk of electrochemical corrosion caused by the bent conductive plate puncturing the packaging bag 10 and the electrolyte in the electrolyte coming into contact with the metal layer (such as the first metal layer 102 or the second metal layer) of the packaging bag 10, thus improving the reliability of the electrochemical device 100.

[0065] As shown in Figure 2, in some embodiments, the second fold line 74 intersects the first fold line 73 at a first intersection point 740 (the intersection point formed by the second fold). The first fold line 73 includes a first segment 731 and a second segment 732, and the boundary point between the first segment 731 and the second segment 732 is the first intersection point 740. The first segment 731 is disposed on the first fold portion 71. The second segment 732 and the second fold line 74 are disposed on the second fold portion 72, and the second segment 732 and the second fold line 74 are actually two sides of the second fold portion 72. In some embodiments, when 45°≤α≤75°, when viewed from the second direction Y, the first intersection point 740 overlaps with the sealing area 1212. By setting the first intersection point 740 to overlap with the sealing area 1212, the position of the first intersection point 740 is shifted upward along the first direction X, which can disperse stress and thereby reduce the risk of the packaging bag 10 breaking at the first intersection point 740. Considering that the packaging bag 10 may break at the first intersection point 740 due to the relatively large included angle α, by setting the first intersection point 740 to overlap with the sealing area 1212, even if the packaging bag 10 breaks at the first intersection point 740, the position of the first intersection point 740 can isolate the broken area from the electrolyte. This reduces the risk of electrochemical corrosion or leakage at the first intersection point 740 and improves the reliability of the electrochemical device 100. That is, the electrochemical device 100 can achieve both high energy density and reliability. In other embodiments, when 45°≤α≤75°, the first intersection point 740 may also overlap with the transition area 1213 when viewed from the second direction Y. By setting the first intersection point 740 to overlap with the transition region 1213 (i.e., the first intersection point 740 is relatively lowered), the second corner portion 72 formed by the second fold can have a larger area, thereby further reducing the size of the first sealing portion 121 in the third direction Z and the size of the second sealing portion 122 in the first direction X, and improving the energy density of the electrochemical device 100.

[0066] As shown in Figure 3, in some embodiments, when 15°≤α<45°, when viewed from the second direction Y, the first intersection point 740 overlaps with the transition region 1213. Since the included angle α is relatively small, the risk of the packaging bag 10 breaking at the first intersection point 740 is also relatively low. Therefore, the overlap between the first intersection point 740 and the transition region 1213 is set (i.e., the first intersection point 740 is relatively lowered), so that the second folded corner portion 72 formed by the second fold can have a larger area, thereby further reducing the size of the first sealing portion 121 in the third direction Z and the size of the second sealing portion 122 in the first direction X, and improving the energy density of the electrochemical device 100.

[0067] The sealing area 1212 includes a third edge 1212A and a fourth edge 1212B disposed opposite to each other in the first direction X. Within the first area 1211, the third edge 1212A is closer to the transition area 1213 than the fourth edge 1212B. The first conductive plate 30 intersects the third edge 1212A and the fourth edge 1212B successively along the first direction X. The width W1 of the sealing area 1212 is the distance between the third edge 1212A and the fourth edge 1212B in the first direction X. When the first intersection point 740 overlaps with the sealing area 1212 when viewed from the second direction Y, it can be positioned in the first direction X, with the distance between the first intersection point 740 and the third edge 1212A within the first area 1211 being L, where L > 0.3 mm. Therefore, even if the packaging bag 10 is damaged at the first intersection point 740, the risk of electrochemical corrosion or leakage can be further reduced, improving the reliability of the electrochemical device 100.

[0068] Referring to Figures 1 and 2, when viewed from the third direction Z, the second sealing portion 122 includes a first edge 122A and a second edge 122B disposed opposite each other in the second direction Y, with the second edge 122B connecting to the first sidewall 113. As shown in Figure 7, before folding to form the second sealing portion 122, the first edge 122A and the second edge 122B are disposed opposite each other in the third direction Z. As shown in Figures 1 and 2, after forming the second sealing portion 122, when viewed from the second direction Y, the first edge 122A and the second edge 122B can largely overlap. Moreover, since the packaging bag 10 has a certain thickness, when viewed from the third direction Z, both the first edge 122A and the second edge 122B have a certain thickness in the third direction Z. The first segment 731 intersects the first edge 122A at a second intersection point 7310 (the intersection formed by the first fold, specifically, the intersection point of the first segment 731 and the outer edge of the first edge 122A). In some embodiments, when viewed from the second direction Y, the first intersection point 740 and the second intersection point 7310 do not coincide. More specifically, in the first direction, the first intersection point 740 is located above the second intersection point 7310. This reduces the risk of damage to the packaging bag 10 caused by the first and second folds occurring at the same intersection point, and also facilitates improved production efficiency. In some embodiments, when viewed from the second direction Y, the second intersection point 7310 may overlap with the third section 1203 of the connecting area 1200, or it may overlap with the transition area 1213.

[0069] As shown in Figures 2 and 10, in some embodiments, viewed from the second direction Y, the angle between the first segment 731 and the first direction X is defined as β, where 0° < β ≤ 15°. This not only facilitates subsequent folding and improves the effect of subsequent folding, but also reduces the risk that the folded area A formed after the first fold is too close to the first conductive plate 30, or that the first conductive plate 30 might be bent during the first fold. Where β < α. Since the second folded corner 72 has a larger folding angle, it can reduce the risk of the second folded corner 72 opening compared to the first folded corner 71 to a certain extent, and also helps to improve the energy density of the electrochemical device 100.

[0070] To further reduce the risk of the second corner portion 72 opening open relative to the first corner portion 71, the first corner portion 71 and the second corner portion 72 can be bonded together. Specifically, a first adhesive member 50 can be provided between the first corner portion 71 and the second corner portion 72. The first adhesive member 50 can be provided at the overlap of the first corner portion 71 and the second corner portion 72. The first adhesive member 50 can be double-sided adhesive or hot melt adhesive. The material of the adhesive layer in the double-sided adhesive can be selected from one or more of acrylate, polyurethane, rubber, and silicone. The hot melt adhesive can be selected from one or more of polyolefin hot melt adhesives, polyurethane hot melt adhesives, ethylene and its copolymers hot melt adhesives, polyester hot melt adhesives, polyamide hot melt adhesives, styrene and its block copolymers hot melt adhesives; this application does not impose any limitations.

[0071] It is understood that in some embodiments, the first sealing portion 121 and the third sealing portion 123 intersect in another connection area (not shown in the figure). This connection area can also be folded N times toward the first end wall 111 to form another angled structure 80 (see Figure 1), thereby further improving the energy density of the electrochemical device 100. The formation method and specific structure of the angled structure 80 are similar to those of the angled structure 70, and will not be described again here.

[0072] Referring to Figure 11, another embodiment of this application also provides an electrochemical device 200. Unlike the electrochemical device 100 described above, after the second fold, the connection area 1200 is folded at least once more, thereby further adjusting the angle structure 70 to further improve the energy density. In this embodiment, N = 3, meaning the connection area 1200 is folded three times towards the first end wall 111 to form the angle structure 70. The angle structure 70 includes a first angle portion 71, a second angle portion 72, and a third angle portion 75. The first angle portion 71 is formed by folding the connection area 1200 along the first angle line 73 towards the first end wall 111 for the first time. The second angle portion 72 is formed by folding the connection area 1200 along the second angle line 74 towards the first end wall 111 for the second time. The third angle portion 75 is formed by folding the connection area 1200 along the third angle line 76 towards the first end wall 111 for the third time. At this time, the angle between the third angle line 76 and the first direction X is the aforementioned angle α. Viewed from the second direction Y, the first folded portion 71, the second folded portion 72, and the third folded portion 75 overlap in pairs. In order to reduce the risk that the third folded portion 75 will open up compared to the second folded portion 72, the second folded portion 72 and the third folded portion 75 can also be bonded together.

[0073] In some embodiments, the first fold line 73 includes a first segment 731 and a second segment 732 connected together, and the boundary point between the first segment 731 and the second segment 732 is the first intersection point 740. The first segment 731 is disposed on the first fold portion 71. The second fold line 74 includes a third segment 742 and a fourth segment 743 connected together, and the boundary point between the third segment 742 and the fourth segment 743 is the third intersection point 761, which is also the intersection point of the third fold line 76 and the second fold line 74 (the intersection point formed by the third fold). Therefore, the third fold is based on a point on the second fold line 74 and is folded around the third fold line 76. The second segment 732 and the third segment 742 are disposed on the second fold portion 72, and the second segment 732 and the third segment 742 are actually two sides of the second fold portion 72. The fourth segment 743 and the third fold line 76 are set on the third fold part 75. The fourth segment 743 and the third fold line 76 are actually the two sides of the third fold part 75.

[0074] At this point, when viewed from the second direction Y, the first intersection point 740 and the third intersection point 761 do not coincide, thereby reducing the risk of damage to the packaging bag 10 caused by the second and third folds occurring at the same intersection point. In the first direction X, the distance between the third intersection point 761 and the first end wall 111 is greater than the distance between the first intersection point 740 and the first end wall 111. That is, in the first direction X, the third intersection point 761 is located above the first intersection point 740. Considering that the overlap of the first folded portion 71 and the second folded portion 72 after the second fold contains four layers of sealing film, and the fact that the third intersection point 761 is located above the first intersection point 740 means that there are four layers of sealing film at the third intersection point 761, resulting in a risk of damage to the packaging bag 10 at the third intersection point 761 after the third fold, it can be set so that when viewed from the second direction Y, the third intersection point 761 overlaps with the sealing area 1212. Thus, even if the packaging bag 10 is damaged at the third intersection point 761, the risk of electrochemical corrosion or leakage can be reduced, and the reliability of the electrochemical device 100 can be improved.

[0075] As shown in Figure 12, in some embodiments, the third fold is based on a point on the first segment 731 of the first fold line 73, and is folded around the third fold line 76. In this case, the first segment 731 of the first fold line 73 is divided into a first segment 7311 and a second segment 7312 after the third fold, with the second segment 7312 connecting to the second fold line 74. The boundary point between the second segment 7312 and the second fold line 74 is the first intersection point 740, and the boundary point between the first segment 7311 and the second segment 7312 is the third intersection point 761, which is also the intersection point of the third fold line 76 and the first segment 731. The first segment 7311 is located on the first fold portion 71. The second segment 7312, the second fold line 74, and the third fold line 76 are disposed on the third fold part 75. The second segment 7312, the second fold line 74, and the third fold line 76 are actually the three sides of the third fold part 75.

[0076] At this point, when viewed from the second direction Y, the first intersection point 740 and the third intersection point 761 do not coincide, thereby reducing the risk of damage to the packaging bag 10 caused by the second and third folds occurring at the same intersection point. In the first direction X, the third intersection point 761 is located between the first intersection point 740 and the first end wall 111. That is, in the first direction X, the third intersection point 761 is located below the first intersection point 740. As shown in Figure 12, when viewed from the second direction Y, the third intersection point 761 can overlap with the transition zone 1213, so the third folded corner portion 75 formed by the third fold can have a larger area, thereby further reducing the size of the first sealing portion 121 in the third direction Z and the size of the second sealing portion 122 in the first direction X, and increasing the energy density of the electrochemical device 200. In other embodiments, when viewed from the second direction Y, the third intersection point 761 may also overlap with the sealing area 1212, so that the third folded portion 75 formed by the third fold can have a larger area, thereby further reducing the size of the first sealing portion 121 in the third direction Z and the size of the second sealing portion 122 in the first direction X, improving the energy density of the electrochemical device 200, and even if the packaging bag 10 is damaged at the third intersection point 761, the risk of electrochemical corrosion or leakage can be reduced, improving the reliability of the electrochemical device 100.

[0077] Referring to Figure 13, another embodiment of this application provides an electrochemical device 300. Unlike the electrochemical devices 100 or 200 described above, the electrochemical device 300 further includes a circuit board 90, which is electrically connected to the first conductive plate 30 and the second conductive plate 40. The circuit board 90 is used to provide electrical protection for the electrode assembly 20, such as charge / discharge protection, and to detect overvoltage, undervoltage, overcurrent, short circuit, and overtemperature conditions of the electrode assembly 20, thereby protecting and extending the service life of the electrochemical device 300. The first sealing portion 121 and the first end wall 111 together form an accommodating space S2, within which the circuit board 90 is disposed. During fabrication, after connecting the first conductive plate 30 and the second conductive plate 40, the circuit board 90 can be folded to the first sealing portion 121 and housed within the accommodating space S2. Therefore, the impact of the circuit board 90 on the energy density of the electrochemical device 300 can be reduced.

[0078] The electrochemical device 100 (or electrochemical device 200, 300) of this application includes all devices capable of undergoing electrochemical reactions. Specifically, the electrochemical device 100 includes all types of primary cells, secondary cells, fuel cells, solar cells, and capacitors (e.g., supercapacitors). Optionally, the electrochemical device 100 can be a lithium secondary battery, including lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, and lithium-ion polymer secondary batteries.

[0079] Referring to Figures 14 and 15, another embodiment of this application provides an electronic device 1, which includes an electrochemical device 300 (or electrochemical devices 100, 200) and a battery compartment 2 for housing the electrochemical device 100. In some embodiments, the battery compartment 2 is at least partially arc-shaped. Due to the N folds, the shape of the corners of the electrochemical device 100 can be adjusted according to actual needs, thus the shape of the electrochemical device 100 can match the actual shape of the battery compartment 2. Meanwhile, if the connection area 1200 of the electrochemical device 100 is not folded or has only undergone one fold, in order to accommodate the arc-shaped inner wall of the battery compartment 2, the dimensions of the electrochemical device 100 in the first direction X and the third direction Z need to be reduced accordingly, thereby reducing the energy density. This application reduces the impact of a battery compartment 2 with a specific shape on the energy density of the electrochemical device 100 by folding the connection area 1200 toward the first end wall 111 N times and setting an angle α between the fold line of the last fold and the first direction X.

[0080] The electrochemical device 100 of this application is applicable to electronic devices 1 in various fields. In one embodiment, the electronic device 1 of this application may be, but is not limited to, laptops, pen input 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, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, household large-capacity batteries, and lithium-ion capacitors, etc.

[0081] Referring to Figure 16, another embodiment of this application also provides a method for preparing the above-described electrochemical device 100 (or electrochemical device 200, 300). Depending on different requirements, the order of steps in the preparation method can be changed, and some steps can be omitted or combined. The preparation method includes the following steps:

[0082] Step S1: Prepare electrode assembly 20, and electrically connect electrode assembly 20 to conductive plate.

[0083] In step S2, the electrode assembly 20 with the conductive plate is placed into the packaging bag 10 and sealed to form a sealing part 12. The conductive plate extends out of the packaging bag 10 from the first sealing part 121.

[0084] Step S3: Fold the sealing part 12 so that it is positioned opposite the first sidewall 113 in the third direction Z to form the second sealing part 122.

[0085] Step S4: Fold the connecting area 1200 toward the first end wall 111 N times to form a folded structure 70.

[0086] The present application will be described in detail below through specific embodiments and comparative examples. The example used is a lithium-ion pouch cell with a wound electrode assembly, and the specific preparation process and testing methods are explained in conjunction with these examples. Those skilled in the art should understand that the preparation methods described in this application are merely examples, and any other suitable preparation methods are within the scope of this application.

[0087] Examples 1-13

[0088] (1) Preparation of the positive electrode sheet: Lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 96.5:1.5:2. N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75 wt%, and the mixture was stirred evenly. Foaming adhesive was first applied to a portion of the surface of the positive electrode current collector, i.e., aluminum foil, with a thickness of 9 μm. The slurry was then uniformly coated on one surface of the aluminum foil. The foil was heated to remove the foaming adhesive and expose a portion of the aluminum foil surface. The foil was then dried at 90°C. The coating process was repeated on the other surface of the aluminum foil to obtain a double-coated positive electrode sheet. The initial positive electrode sheet was cold-pressed to obtain a single coating layer of positive active material with a thickness of 77 μm. The positive electrode sheet was then cut to obtain the positive electrode sheet. Finally, a second conductive plate made of aluminum was welded onto the exposed aluminum foil.

[0089] (2) Preparation of the negative electrode sheet: Artificial graphite, silicon carbide, conductive carbon black (Super P), polyacrylic acid binder (PAA), and lithium difluorophosphate (LDPF) were mixed in a weight ratio of 69:5:6:19:1, with deionized water added as a solvent to prepare a slurry with a weight percentage of 55 wt%, and stirred evenly. Foaming adhesive was pre-applied to a portion of the copper foil (5 μm thick) of the negative electrode current collector. The slurry was then uniformly coated onto one surface of the copper foil, heated to remove the foaming adhesive and expose the copper foil portion, and then dried at 90°C. The coating process was repeated on the other surface of the copper foil to obtain a double-sided coated negative electrode sheet. The initial negative electrode sheet was rolled to obtain a negative electrode active material layer with a coating thickness of 70 μm. Then, a first conductive plate made of nickel was welded onto the exposed copper foil.

[0090] (3) Preparation of electrolyte: In a dry argon atmosphere, the organic solvents ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are first mixed in a mass ratio of EC:EMC:DEC = 30:50:20. Then, lithium salt lithium hexafluorophosphate (LiPF6) is added to the organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0091] (4) Preparation of the isolation membrane: A polyethylene (PE) membrane with a thickness of 9 μm was selected.

[0092] (5) Battery fabrication: The positive electrode, separator, and negative electrode are sequentially stacked and wound to obtain the electrode assembly. Then, an aluminum-plastic film (150 μm thick) with a dented surface is placed in the assembly fixture with the dented surface facing upwards. The electrode assembly is placed in the dent of the aluminum-plastic film, and then electrolyte is injected into the dent. The first and second conductive plates are then led out of the aluminum-plastic film and sealed to obtain a packaging bag. At this time, the battery capacity D is measured to be 225 mAh.

[0093] (6) Folding of the packaging bag: Fold the sealing part of the packaging bag to form the second sealing part and the third sealing part. At this time, the length L0, width W0, and height H0 of the battery are measured to be 24.57mm × 20.91mm × 3.28mm, respectively, using an optical measuring instrument. Then, fold the two connecting areas twice towards the first end wall to form two identical folded corner structures, where the first intersection point is located in the transition area of ​​the packaging bag. The difference between the embodiments lies in the value of the included angle α. The relevant parameters are recorded in Table 1.

[0094] Examples 14-20

[0095] The difference from Examples 7-13 is that the first intersection point is located in the sealing area of ​​the packaging bag.

[0096] Comparative Example 1

[0097] The difference from Embodiment 1 is that after the sealing part is folded to be positioned opposite the first sidewall to form the second sealing part, the connecting area is not folded toward the first end wall.

[0098] Comparative Example 2

[0099] The difference from Example 1 lies in the value of the included angle α.

[0100] Then, the energy density improvement rate and packaging bag breakage rate of the batteries in each embodiment and comparative example were tested. Twenty batteries from each embodiment and comparative example were tested, and the corresponding test results are recorded in Table 1.

[0101] The test steps for the energy density improvement rate are as follows: 1) Calculate the energy density ED1 of the battery before the corner structure is formed, ED1 = D / (L0×W0×H0); 2) After the corner structure is formed, calculate the energy density ED2 of the battery using a similar method. The ratio of the difference between ED2 and ED1 to ED1 is the energy density improvement rate of the battery.

[0102] The test steps for the packaging bag damage rate are as follows: 1) Place the fully charged battery in a high temperature and high humidity environment of 60℃ and let it stand for 15 days. Then, observe under a magnifying glass whether black spots appear around the first intersection of the packaging bag. If black spots appear, it indicates that the packaging bag is damaged or broken around the first intersection and causes electrochemical corrosion.

[0103] Table 1

[0104] As can be seen from the data in Table 1, compared to Comparative Example 1, Examples 1-13 have an angled structure, thus improving the energy density of the battery. In Comparative Example 2, the included angle α is too large. Although the energy density of the battery is improved, the risk of the packaging bag breaking or tearing at the first intersection point is also correspondingly higher. Compared to Comparative Example 2, the included angle α in Examples 1-13 satisfies 15°≤α≤75°, thus the battery can simultaneously achieve both high energy density and reliability.

[0105] Compared to Examples 7-13, in Examples 14-17, when the included angle α satisfies 45°≤α≤75°, by setting the first intersection point to be located in the sealed area, the risk of the packaging bag being damaged or broken at the first intersection point and causing electrochemical corrosion is reduced. Therefore, the battery can simultaneously achieve high energy density and reliability.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the scope of the technical solutions of this application.

Claims

1. An electrochemical device, comprising a packaging bag, an electrode assembly and a conductive plate, the packaging bag comprising a main body portion and a sealing portion, the electrode assembly being arranged in the main body portion, the conductive plate being electrically connected to the electrode assembly; the conductive plate extends out of the packaging bag along a first direction, a thickness direction of the electrode assembly being a second direction, a direction perpendicular to the first direction and the second direction being a third direction, the main body portion comprising a first end wall and a second end wall oppositely arranged in the first direction, the main body portion further comprising a first side wall and a second side wall oppositely arranged in the third direction; wherein, the sealing portion comprises a first sealing portion and a second sealing portion, the first sealing portion being connected to the first end wall, the conductive plate extending out of the packaging bag from the first sealing portion; the second sealing portion being connected to the first side wall, the second sealing portion and the first side wall being oppositely arranged in the third direction; the first sealing portion and the second sealing portion intersecting in a connecting area, the connecting area being folded towards the first end wall N times to form a fold angle structure, N being an integer greater than or equal to 2; the fold angle structure comprising N fold angle portions, an Nth fold angle portion being formed by folding the connecting area along an Nth fold angle line towards the first end wall for the Nth time, an included angle between the Nth fold angle line and the first direction being a, 15°≤a≤75°. the packaging bag comprising a first packaging film and a second packaging film oppositely arranged in the second direction, the first packaging film comprising a first packaging layer, the second packaging film comprising a second packaging layer; the first sealing portion comprising a sealing area and a transition area, the transition area being connected to the main body portion and the sealing area respectively in the first direction, the first packaging layer and the second packaging layer being bonded in the sealing area, the first packaging layer and the second packaging layer being separated in the transition area; a width of the sealing area in the first direction being 1.0mm to 2.0mm, a width of the transition area in the first direction being 0.3mm to 1.0mm. N=2, the fold angle structure comprising a first fold angle portion and a second fold angle portion, the first fold angle portion being formed by folding the connecting area along a first fold angle line towards the first end wall for the first time, the second fold angle portion being formed by folding the connecting area along a second fold angle line towards the first end wall for the second time; from the second direction, the first fold angle portion and the second fold angle portion overlap. the first fold angle line and the second fold angle line intersecting at a first intersection point, from the second direction, the first intersection point overlapping with the transition area.

2. The electrochemical device of claim 1, wherein, 45°≤a≤75°, the first fold angle line and the second fold angle line intersecting at a first intersection point, from a second direction, the first intersection point overlapping with the sealing area. the first fold angle line comprising a first segment and a second segment connected to each other, the first segment being arranged on the first fold angle portion, the second segment and the second fold angle line being arranged on the second fold angle portion.

3. The electrochemical device of claim 2, wherein, ​ 4. The electrochemical device of claim 3, wherein, ​ 5. The electrochemical device of claim 3, wherein, ​ 6. The electrochemical device of any one of claims 3 to 5, wherein, ​ 7. The electrochemical device of any one of claims 3 to 6, wherein, The second sealing part comprises a first edge and a second edge oppositely arranged in the second direction, the second edge connecting the first side wall; the first segment intersects the first edge at a second intersection point, the first intersection point and the second intersection point do not coincide in the second direction.

8. The electrochemical device of claim 6, wherein, An included angle between the first segment and the first direction is β in the second direction, 0°<β≤15°.

9. The electrochemical device of claim 5, wherein, The first sealing part comprises a first region and the connecting region, the first region connecting part of the first end wall, the connecting region comprising a first sub-region and a second sub-region, the second sub-region connecting another part of the first end wall and the first region respectively, the first sealing part and the second sealing part intersecting at the first sub-region; the first corner part comprises part of the second sub-region.

10. The electrochemical device of claim 9, wherein, The sealing region comprises a third edge and a fourth edge oppositely arranged in the first direction; in the first region, the third edge is closer to the transition region than the fourth edge; in the first direction, the distance between the first intersection point and the third edge in the first region is L, L>0.3mm.

11. The electrochemical device of any one of claims 3 to 10, wherein, The electrochemical device further comprises a first adhesive, the first adhesive respectively bonding the first corner part and the second corner part.

12. The electrochemical device of claim 2, wherein, N=3, the corner structure comprises a first corner part, a second corner part and a third corner part, the first corner part being formed by first folding the connecting region along a first corner line towards the first end wall, the second corner part being formed by second folding the connecting region along a second corner line towards the first end wall, the third corner part being formed by third folding the connecting region along a third corner line towards the first end wall; the first corner part, the second corner part and the third corner part overlap with each other in the second direction.

13. The electrochemical device of claim 12, wherein, The first corner line comprises a first segment and a second segment connected to each other, the first segment being arranged on the first corner part; the second corner line comprises a third segment and a fourth segment connected to each other, the second segment and the third segment being arranged on the second corner part, and the fourth segment and the third corner line being arranged on the third corner part.

14. The electrochemical device of claim 12 or 13, wherein, The third corner line intersects the second corner line at a third intersection point, in the first direction, the distance between the third intersection point and the first end wall is greater than the distance between the first intersection point and the first end wall; the third intersection point overlaps with the sealing region in the second direction.

15. The electrochemical device of claim 12, wherein, The first corner line comprises a first segment and a second segment connected to the first segment, the first segment comprises a first sub-segment and a second sub-segment connected to each other, the second sub-segment connecting the second corner line, the first sub-segment being arranged on the first corner part, and the second sub-segment, the second corner line and the third corner line being arranged on the third corner part.

16. The electrochemical device of claim 15, wherein, The third fold line intersects the first segment at a third intersection point, which is located between the first intersection point and the first end wall in the first direction; and the third intersection point overlaps with the sealing area or the transition area as viewed from the second direction.

17. The electrochemical device of any one of claims 1 to 16, wherein, The electrochemical device further comprises a circuit board electrically connected with the conductive plate; the first sealing part and the first end wall jointly form a containing space, and the circuit board is arranged in the containing space. 18.An electronic device comprising a battery compartment, wherein the electronic device further comprises the electrochemical device according to any one of claims 1 to 17, and the electrochemical device is arranged in the battery compartment.

19. The electronic device of claim 18, wherein, The battery compartment is at least partially arc-shaped.

20. A method of producing an electrochemical device as claimed in any one of claims 1 to 17, wherein, The preparation method comprises the following steps: preparing the electrode assembly, which is electrically connected with the conductive plate; packing the electrode assembly with the conductive plate into the packaging bag and sealing the packaging bag to form the sealing part, and the conductive plate extends out of the packaging bag from the first sealing part; folding the sealing part to be opposite to the first side wall in the third direction to form the second sealing part; folding the connecting area towards the first end wall for N times to form the fold angle structure. The third fold line intersects the first segment at a third intersection point, which is located between the first intersection point and the first end wall in the first direction; and the third intersection point overlaps with the sealing area or the transition area as viewed from the second direction. The electrochemical device further comprises a circuit board electrically connected with the conductive plate; the first sealing part and the first end wall jointly form a containing space, and the circuit board is arranged in the containing space. 18.An electronic device comprising a battery compartment, wherein the electronic device further comprises the electrochemical device according to any one of claims 1 to 17, and the electrochemical device is arranged in the battery compartment. The battery compartment is at least partially arc-shaped. The preparation method comprises the following steps: preparing the electrode assembly, which is electrically connected with the conductive plate; packing the electrode assembly with the conductive plate into the packaging bag and sealing the packaging bag to form the sealing part, and the conductive plate extends out of the packing bag from the first sealing part; folding the sealing part to be opposite to the first side wail in the third direction to form the second sealing part; folding the connecting area towards the first encl wall for N times to form the fold angle structure.

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