Electrochemical and Electronic Devices

Abstract

The electrochemical device includes a housing, an electrode assembly, and a tab. The housing includes a main body and a first part. In a second direction, the main body includes a first wall and a second wall arranged opposite to each other, and in a third direction, the main body includes a first side wall and a second side wall arranged opposite to each other. The first part includes a first seal edge connecting the first side wall and the second wall, and a second seal edge connecting the first seal edge, and the second seal edge is provided between the first seal edge and the first side wall. The housing includes a first housing and a second housing arranged opposite to each other. The first housing has a first polymer layer, and the second housing has a second polymer layer, and the first polymer layer and the second polymer layer are bonded to form a colloid. In a cross section perpendicular to the first direction, there is a first connection point between the first seal edge and the first side wall. The first side wall forms a first straight line extending outwardly along a contour of the first side wall at the first connection point. The colloid is located within a space defined by the first portion and the first straight line. The present application further provides an electronic device. The present application improves service life and safety.

Description

[Technical field]

[0001] The present application relates to the field of energy storage technology, and in particular to electrochemical devices and electronic devices having the same. [Background technology]

[0002] Electrochemical devices (such as batteries) are widely used in electronic products such as portable electronic devices, power tools, and electric vehicles, and the requirements for safety performance of electrochemical devices are becoming increasingly higher.

[0003] In the manufacturing process of the electrochemical device, the upper and lower layers of the encapsulation film must be heat-sealed by a sealing head to form a housing, and the electrode assembly and the electrolyte must be sealed inside the housing. Mechanical abuse (dropping, collision, vibration) can cause the housing to break, leading to leakage or short circuit, reducing the life and safety of the electrochemical device. Summary of the Invention

[0004] In view of the shortcomings in the prior art, there is a need to propose an electrochemical device. There is also a need to provide an electronic device having such an electrochemical device.

[0005] The present application provides an electrochemical device including a housing, an electrode assembly, and a tab. The housing includes a main body and a first part, the electrode assembly is provided on the main body, and the tab is electrically connected to the electrode assembly and protrudes from the housing. If a direction in which the tab protrudes relative to the electrode assembly is defined as a first direction, a thickness direction of the electrode assembly is defined as a second direction, and a direction perpendicular to the first and second directions is defined as a third direction, in the second direction, the main body includes a first wall and a second wall arranged opposite to each other, and in the third direction, the main body includes a first side wall and a second side wall arranged opposite to each other. The first part includes a first seal edge connecting the first side wall and the second wall, and a second seal edge connecting the first seal edge, and the second seal edge is provided between the first seal edge and the first side wall. The housing includes a first housing and a second housing arranged opposite to each other.

[0006] The first housing has a first polymer layer and the second housing has a second polymer layer, the first polymer layer and the second polymer layer are bonded to form a colloid, the colloid being located in the first portion. In a cross section perpendicular to the first direction, there is a first connection point between the first seal edge and the first sidewall. At the first connection point, the first sidewall forms a first straight line extending outwardly along a contour of the first sidewall. The colloid is located within a space formed by the first portion and the first straight line.

[0007] The present application limits the scope of the colloid to reduce the impact force of the colloid on the first connection point during mechanical abuse, thereby reducing the risk of rupture at the connection point and improving the mechanical strength of the first part, as well as reducing the risk of the colloid hitting the electrode assembly during mechanical abuse, thereby improving the life and safety of the electrochemical device.

[0008] In some possible embodiments, a straight line passing through the first connection point and extending along the second direction is defined as the second straight line. The colloid is located in a space formed by being surrounded by the first part and the second straight line. By defining the position of the colloid, the impact force of the colloid on the first connection point during mechanical abuse is further reduced, and the risk of the colloid hitting the electrode assembly is also further reduced. In addition, by forming a buffer space for containing the electrolyte between the first straight line, the second straight line, and the second wall, the risk of leakage due to the electrolyte being broken through the first part during mechanical abuse is reduced, thereby improving safety.

[0009] In some possible embodiments, the sum of the length of the first seal edge and the length of the second seal edge in the second direction is L, and the thickness of the electrode assembly in the second direction is H, where 3 / 4H≦L≦5 / 4H. This improves the problem of the sealing strength of the first part decreasing when the L value is too small, reduces the risk of the first part being broken by the electrode assembly or the electrolyte, and also improves the problem of increased costs and reduced energy density when the L value is too large.

[0010] In some possible embodiments, the second seal edge includes a first end connected to the first seal edge and a second end disposed opposite to the first end. The electrode assembly has a first surface perpendicular to the second direction, and the thickness of the electrode assembly located on both sides of the first surface in the second direction is the same. The first surface is located between the second end and the second wall. Therefore, the risk that the first part is easily separated from the first side wall when the position of the second end is low (i.e., the second seal edge length is large) is reduced.

[0011] In some possible embodiments, the first seal edge includes a first region and a second region, the second region being connected between the first region and the second seal edge, and the thickness of the first region is greater than the thickness of the second region.

[0012] In some possible embodiments, a second connection point is provided between the first region and the second region in a cross section perpendicular to the first direction. The electrode assembly has a first surface perpendicular to the second direction. In the second direction, the thickness of the electrode assembly located on both sides of the first surface is the same. The second connection point is located between the first surface and the second wall. By defining the position of the second connection point, the dimension of the first region in the second direction is reduced, and the dimension of the second region having a greater sealing strength in the second direction is increased, thereby improving the sealing strength of the first part.

[0013] In some possible embodiments, a third connection point is provided between the second region and the second seal edge in a cross section perpendicular to the first direction. The electrode assembly has a second surface perpendicular to the second direction, and the thickness of the electrode assembly located between the second surface and the second wall in the second direction is 3 / 4 of the thickness of the entire electrode assembly. In the second direction, the third connection point is located between the second surface and the second wall. Thus, when the third connection point is high (i.e., the second seal edge length is large), the risk that the first part is easily separated from the first side wall is reduced.

[0014] In some possible embodiments, the first seal edge includes a third region, and the first region is connected between the second region and the third region. The first polymer layer in the third region is not bonded to the second polymer layer. In a cross section perpendicular to the first direction, there is a first connection point between the first seal edge and the first side wall. A straight line passing through the first connection point and extending along the second direction is defined as a second straight line, and the third region is provided on one side of the second straight line. By disposing the third region, the impact force of the colloid on the first connection point during mechanical abuse is further reduced, and the risk of the colloid hitting the electrode assembly is also further reduced. In addition, the third region forms a buffer space that contains the electrolyte, and the risk of the first part being broken by the electrolyte and leaking when mechanical abuse occurs is reduced, thereby improving safety.

[0015] In some possible embodiments, the first housing further includes a first metal layer laminated on the first polymer layer. The second housing further includes a second metal layer laminated on the second polymer layer. In a cross section perpendicular to the first direction, when the area of ​​the portion where the third region is provided between the first metal layer and the second metal layer is A1, and the area of ​​the portion where the first region is provided between the first metal layer and the second metal layer is A2, 0.5≦A1:A2≦3 is satisfied. This improves the problem that the first part is difficult to bend at the connection part with the first side wall when the ratio of A1 to A2 is too small, and the dimension of the electrochemical device in the third direction after bending is reduced, thereby improving the volumetric energy density. In addition, when the ratio of A1 to A2 is too large, the risk of the sealing strength of the first part decreasing is also reduced.

[0016] In some possible embodiments, in a cross section perpendicular to the first direction, the colloid in the first region includes a corner point, and the corner point protrudes toward the third region. The first housing further includes a first metal layer laminated on the first polymer layer, and the second housing further includes a second metal layer laminated on the second polymer layer. The third straight line passes through the corner point and is parallel to the second straight line, and the third straight line intersects with the boundary line between the first metal layer and the first polymer layer of the first seal edge at a first intersection point, and the third straight line intersects with the second metal layer and the second polymer layer of the first seal edge at a second intersection point. If the distance between the first intersection point and the second intersection point is L3, and the distance between the corner point and the boundary line between the first region and the second region is L4, then 0.1≦L4 / L3≦0.6. This improves the problem that the heat seal of the second region is insufficient when the ratio of L3 to L4 is too small or too large, and improves the sealing strength of the first part.

[0017] In some possible embodiments, the sealing device further comprises a first adhesive that bonds the second sealing edge to an outer surface of the first side wall, thereby reducing the risk of the first part coming apart.

[0018] In some possible embodiments, a second adhesive is provided to bond the electrode assembly to the inner surface of the first side wall, thus reducing the risk of the electrode assembly moving about within the housing in the third direction in the event of mechanical abuse, thus reducing the impact of the electrode assembly against the first part of the housing and improving safety.

[0019] In some possible embodiments, the electrode assembly may further include a third adhesive that bonds the electrode assembly to the inner surface of at least one of the first wall or the second wall, thereby reducing the risk of the electrode assembly moving about in the housing in the second direction when mechanical abuse occurs, and thus reducing the impact of the electrode assembly against the second part of the housing, thereby improving safety.

[0020] In some possible embodiments, the electrode assembly is a wound structure. The electrode assembly includes a first electrode sheet, a second electrode sheet, and a separator provided between the first electrode sheet and the second electrode sheet. The first electrode sheet includes a first current collector and a first active material layer provided on the first current collector. The first current collector has a first surface, and the outermost surface of the electrode assembly is the first surface. Even if the colloid impacts the electrode assembly, the first surface is the outer surface, so that when an active material is provided on the outer surface of the electrode assembly, the active material is prevented from falling off. Meanwhile, the first current collector can increase the hardness of the electrode assembly and serves to protect the electrode assembly.

[0021] In some possible embodiments, the electrode assembly is a wound structure. The electrode assembly includes a first electrode sheet, a second electrode sheet, and a separator between the first electrode sheet and the second electrode sheet. The outermost periphery of the electrode assembly is the separator. The separator increases the friction between the electrode assembly and the housing, and increases the adhesive force between the electrode assembly and the first adhesive or the second adhesive, so that the electrode assembly can be more suitably fixed within the housing. In addition, the separator can form a protective layer, which can avoid the risk of short circuit due to wear of the electrode sheet inside the separator in this portion, and can increase the resistance of the electrode assembly to mechanical shock.

[0022] In some possible embodiments, the body further includes a first end wall and a second end wall arranged opposite to each other in the first direction. The housing further includes a second part connecting the first end wall, and the tab protrudes from an edge of the second part to the outside of the housing. The second part can close the body in the first direction, further reducing the risk of liquid leakage.

[0023] In some possible embodiments, the second portion is closer to the second wall than the first wall in the second direction, and the first end wall includes a first end surface and a second end surface located on either side of the tab, the first end surface connecting the second portion to the first wall and the second end surface connecting the second portion to the second wall in the second direction.

[0024] In some possible embodiments, the electrochemical device further includes a fourth adhesive that bonds the first end surface and the edge of the second part. The fourth adhesive can cover the metal layer exposed from the edge of the second part, thereby improving safety.

[0025] In some possible embodiments, the first polymer layer comprises a first polymer material and the second polymer layer comprises a second polymer material, each of which is independently at least one selected from the group consisting of polypropylene, propylene copolymers, polyethylene, and polymethylmethacrylate. The present invention further provides an electronic device comprising the electrochemical device described above. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a perspective view of an electrochemical device according to one embodiment of the present application. [Diagram 2] FIG. 2 is a cross-sectional view of the electrochemical device shown in FIG. 1 taken along line II-II. [Diagram 3] FIG. 3 is a cross-sectional view of the electrochemical device shown in FIG. 1 taken along line III-III. [Figure 4] FIG. 4 is a perspective view of the electrochemical device shown in FIG. 1 before sealing. [Diagram 5] FIG. 5 is a cross-sectional view of a first housing in the electrochemical device shown in FIG. [Figure 6] FIG. 6 is a cross-sectional view of a second housing in the electrochemical device shown in FIG. [Figure 7] FIG. 7 is a front view of the first portion of the electrochemical device shown in FIG. 1 before being folded. [Figure 8] FIG. 8 is a cross-sectional view of the first portion of the electrochemical device shown in FIG. 7 before being folded. [Figure 9] FIG. 9 is a cross-sectional view of the first portion of the electrochemical device shown in FIG. 8 after being folded for the first time. [Figure 10] FIG. 10 is a schematic diagram of a first portion of an electrochemical device according to another embodiment before being folded. [Figure 11] FIG. 11 is a partially enlarged view of the electrochemical device shown in FIG. [Figure 12] FIG. 12 is a partially enlarged view of the electrochemical device shown in FIG. 3 according to another embodiment. [Figure 13] FIG. 13 is a partially enlarged view showing the occurrence of a rupture near the first connection point of the electrochemical device shown in FIG. [Figure 14] FIG. 14 is a partially enlarged view of the electrochemical device shown in FIG. 3 according to another embodiment. [Figure 15A] 15A is a schematic diagram of the first region and the third region of the first sealing edge in the electrochemical device shown in FIG. [Figure 15B] FIG. 15B is a schematic diagram of the area between the first metal layer and the second metal layer in the first region and the third region shown in FIG. 15A. [Figure 16] FIG. 16 is a partially enlarged view of the electrochemical device shown in FIG. 3 according to another embodiment. [Figure 17] FIG. 17 is a cross-sectional view of an electrochemical device according to another embodiment. [Figure 18] FIG. 18 is a schematic diagram showing an overall configuration of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The present disclosure is further explained in the following detailed description in conjunction with the above-mentioned drawings.

[0028] The following will be described clearly and completely with reference to the drawings in the embodiments of the present application. It is clear that each of the described embodiments is only a part of the embodiments of the present application, and is not all of the embodiments. Unless otherwise defined, technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art of the technical field of the present disclosure. The terms used in this specification are only for the purpose of describing specific examples, and are not intended to limit the present application.

[0029] Hereinafter, the embodiments of the present application will be described in detail. The present application can be expanded into many different forms, and should not be construed as being limited to the exemplary embodiments described herein. Providing these exemplary embodiments will enable the present application to be fully and in detail conveyed to those skilled in the art.

[0030] Additionally, sizes and thicknesses of various components and layers may be exaggerated in the figures for simplicity and clarity. Like numbers refer to like elements throughout. As used herein, the term "and / or" or "and / or" includes any and all combinations of one or more of the associated listed items. Additionally, when an element A is "connected" or "connected" to an element B, element A may be directly connected to element B, or an intermediate element C may be present to indirectly connect element A and element B.

[0031] Furthermore, when describing an embodiment of this specification, "can (can or may)" is used, this means "one or more embodiments of this specification."

[0032] The terminology used in this specification is for the purpose of describing specific embodiments and is not intended to limit the present application. In addition, the singular form is used to include the plural form unless the context clearly indicates otherwise. Furthermore, the term "comprises" as used in this specification means that the described features, values, steps, operations, elements, and / or components are present, but does not exclude the presence or addition of one or more other features, values, steps, operations, elements, components, and / or combinations thereof.

[0033] As shown, spatial terms such as "above" may be used herein for convenience of description to describe the relationship of one element or feature to another element(s) or feature(s). It is intended that spatial terms include different orientations depending on the orientation of the device or apparatus in use or operation in addition to the orientation shown in the figure. For example, an element that is "above" or "on" another element or feature would be described as being "below" or "below" the other element or feature if the device in the figure were turned over. Thus, the term "above" may refer to an orientation that includes above and below. Terms such as first, second, third, etc. may describe various elements, components, areas, layers, and / or portions, but these terms are not intended to limit these elements, components, areas, layers, and / or portions. These terms are used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Thus, a first element, component, area, layer or portion below could be termed a second element, component, area, layer or portion without departing from the teachings of the embodiments.

[0034] 1 to 3, an embodiment of the present disclosure provides an electrochemical device 100 including a housing 10, an electrode assembly 20, an electrolyte (not shown), a first tab 30, and a second tab 40. The electrode assembly 20 is located inside the housing 10. In some examples, the electrochemical device 100 may include an electrolyte (not shown) located inside the housing 10. The first tab 30 and the second tab 40 each electrically connect the electrode assembly 20 and protrude from the housing 10. The first tab 30 and the second tab 40 can connect an exterior member (not shown).

[0035] As shown in FIG. 3, in some embodiments, the electrode assembly 20 has a wound structure and includes a first electrode sheet 21, a second electrode sheet 22, and a separator 23 provided between the first electrode sheet 21 and the second electrode sheet 22. The first electrode sheet 21, the separator 23, and the second electrode sheet 22 are stacked and wound to form the electrode assembly 20. The first electrode sheet 21 includes a first current collector 210 and a first active material layer 211 provided on the first current collector 210. The second electrode sheet 22 includes a second current collector 220 and a second active material layer 221 provided on the second current collector 220. Here, as shown in FIG. 3, the electrode assembly 20 has a winding central axis O perpendicular to the paper surface. The winding direction D is a counterclockwise direction around the winding central axis O as shown in FIG. 3. In the winding direction D, the electrode assembly 20 includes a first segment 201, a first bent segment 202, a second segment 203, and a second bent segment 204, which are connected in this order. The first segment 201 and the second segment 203 may be straight segments arranged opposite each other. In some embodiments, the first segment 201 and the second segment 203 may be bent segments, and this is not particularly limited in the present application.

[0036] As shown in Fig. 2, in some embodiments, the first tab 30 has a plurality of connection parts 31 and one adapter part 32. The connection part 31 is connected to the first current collector 210. The adapter part 32 is connected to the connection part 31 and protrudes from the housing 10. Here, the connection part 31 is fixed to the first current collector 210 by integral molding (i.e., the connection part 31 is formed by cutting the first current collector 210) or by welding. The adapter part 32 is fixed to the plurality of connection parts 31 by welding.

[0037] In another embodiment, the electrode assembly 20 may have a laminated structure in which the first electrode sheet 21, the separator 23, and the second electrode sheet 22 are laminated in this order.

[0038] The first electrode sheet 21 may be either a positive electrode sheet or a negative electrode sheet. Correspondingly, the first current collector 210 may be a positive electrode current collector or a negative electrode current collector, and the first active material layer 211 may be a positive electrode active material layer or a negative electrode active material layer. In some embodiments, the first electrode sheet 21 is a positive electrode sheet, and the second electrode sheet 22 is a negative electrode sheet.

[0039] The positive electrode current collector may be made of aluminum foil or nickel foil, and the negative electrode current collector may be made of at least one of copper foil, nickel foil, and a carbon-based current collector.

[0040] The positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes a compound (i.e., a lithiated intercalation compound) that reversibly inserts and extracts metal ions (e.g., lithium ions, sodium ions, etc., hereinafter, lithium ions will be taken as an example). In some embodiments, the positive electrode active material may include a lithium transition metal composite oxide. The lithium transition metal composite oxide includes lithium and at least one element selected from the group consisting of cobalt, manganese, and nickel. In some embodiments, the positive electrode active material is lithium cobalt oxide (LiCoO2), lithium nickel manganese cobalt ternary material (NCM), lithium nickel cobalt aluminum ternary material (NCA), lithium manganese oxide (LiMn2O4), lithium nickel manganese oxide (LiNi0.5Mn 1.5 At least one selected from the group consisting of lithium iron phosphate (LiFePO4) and lithium iron phosphate (LiFePO4).

[0041] The negative electrode active material layer may include a negative electrode active material that is known in the art and capable of reversibly releasing active ions, and is not particularly limited in the present application. For example, the negative electrode active material layer may include, but is not limited to, one or more combinations of graphite, soft carbon, hard carbon, carbon fiber, mesocarbon microbeads, silicon-based materials, tin-based materials, lithium titanate, or other metals that can be alloyed with lithium. Here, the graphite may be one or more combinations selected from artificial graphite, natural graphite, and modified graphite. The silicon-based material may be one or more combinations selected from elemental silicon, silicon oxide, silicon carbon composite, and silicon alloy. The tin-based material may be one or more combinations selected from elemental tin, tin oxide, and tin alloy.

[0042] The separation membrane 23 includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, and aramid. For example, the polyethylene includes at least one selected from high density polyethylene, low density polyethylene, and ultra-high molecular weight polyethylene. Polyethylene and polypropylene are excellent in reducing the risk of short circuit, and can improve the stability of the electrochemical device 100 by the shutdown effect.

[0043] 1 and 3, the housing 10 includes a main body portion 13 and a first portion 11a. The electrode assembly 20 is provided in the main body portion 13. The direction in which the first tab 30 protrudes from the electrode assembly 20 (i.e., the direction from the electrode assembly 20 to the first tab 30) is defined as a first direction D1, the thickness direction of the electrode assembly 20 is defined as a second direction D2, and the direction perpendicular to the first direction D1 and the second direction D2 is defined as a third direction D3. In some embodiments, when the electrode assembly 20 has a wound structure, the first direction D1 is the direction of the winding central axis O. The second direction D2 is the stacking direction of the first electrode sheets 21 of each layer in the first segment 201 or the second segment 203. When the first segment 201 and the second segment 203 are straight segments arranged opposite to each other, the second direction D2 is also perpendicular to the surface of the first segment 201 or the surface of the second segment 203. The third direction is the extension direction of the first electrode sheet 21 in the first segment 201 or the second segment 203. In another embodiment, when the electrode assembly 20 has a laminated structure, the second direction D2 is the laminated direction of the first electrode sheet 21.

[0044] In the second direction D2, the main body 13 includes a first wall 131 and a second wall 132 that are provided opposite to each other. The surface on which the first wall 131 is located extends in the first direction D1 and the third direction D3, and the surface on which the second wall 132 is located extends in the first direction D1 and the third direction D3. In the third direction D3, the main body 13 includes a first side wall 133a and a second wall 133b that are provided opposite to each other. In the second direction D2, the first side wall 133a is connected between the first wall 131 and the second wall 132, and the second side wall 133b is connected between the first wall 131 and the second wall 132. By folding the first portion 11a and providing it on the first side wall 133a, the dimension of the electrochemical device 100 in the third direction D3 is reduced, and the space utilization rate and the energy density are improved. In the first direction D1, the main body 13 includes a first end wall 134 and a second end wall 135 that are provided opposite to each other. A surface on which the first end wall 134 is located extends in the second direction D2 and the third direction D3, and a surface on which the second end wall 135 is located extends in the second direction D2 and the third direction D3. In the second direction D2, the first end wall 134 is connected between the first wall 131 and the second wall 132, and the second end wall 135 is connected between the first wall 131 and the second wall 132. In some embodiments, the housing 10 further includes a third portion 11b. The third portion is connected to the second side wall 133b.

[0045] As shown in FIG. 3, in some embodiments, in the second direction D2, the first wall 131 and the first segment 201 are provided opposite to each other, and the second wall 132 and the second segment 203 are provided opposite to each other. In the third direction D3, the first side wall 133a is provided opposite to the first bent segment 202, and the second side wall 133b is provided opposite to the second bent segment 204. In addition, when the two are provided opposite to each other in a certain direction, it means that the projections of the two almost overlap in that direction. Since the electrochemical device 100 needs to discharge the gas and the excess electrolyte generated during the anodization by evacuation after the anodization, depending on the shape of the side wall of the electrode assembly 20, the first side wall 133a and the second side wall 133b may be a certain arc, that is, the first side wall 133a and the second side wall 133b may both be arc surfaces.

[0046] 1 and 2, the housing 10 may further include a second portion 12a. The second portion 12a is connected to the first end wall 134. At this time, the first tab 30 and the second tab 40 both protrude from the edge of the second portion 12a to the outside of the housing 10. When the first tab 30 includes the connection portion 31 and the adapter portion 32, the adapter portion 32 protrudes from the edge of the second portion 12a to the outside of the housing 10. In some embodiments, the second portion 12a does not need to be bent, that is, the second portion 12a is approximately perpendicular to the first end wall 134. At this time, the direction in which the first tab 30 protrudes from the housing 10 is defined as a first direction D1. In some other embodiments, the second portion 12a is folded up to the first end wall 134, thereby reducing the dimension of the electrochemical device 100 in the first direction D1, and improving the space utilization rate and the energy density. By folding the second portion 12a onto the first end wall 134, a part of the first tab 30 (the adapter portion 32) provided on the second portion 12a is also folded onto the first end wall 134. At this time, the adapter portion 32 is perpendicular to the first direction D1 in the extension direction of the second portion 12a.

[0047] In some embodiments, the electrochemical device 100 further includes a first insulating adhesive 300 and a second insulating adhesive 400. The first insulating adhesive 300 hermetically connects the first tab 30 and the second portion 12a, and a portion of the first insulating adhesive 300 is provided outside the second portion 12a. The second insulating adhesive 400 hermetically connects the second tab 40 and the second portion 12a, and a portion of the second insulating adhesive 400 is provided outside the second portion 12a.

[0048] Referring to FIG. 4, it is a schematic diagram of the electrochemical device 100 before sealing. The housing 10 includes a first housing 101 and a second housing 102 that are provided opposite to each other in the second direction D2. In some embodiments, the second housing 102 is folded with respect to the first housing 101. When the housing 10 includes a first part 11a, a second part 12a, and a third part 11b, the electrode assemblies 20 corresponding to the folded portions of the first housing 101 and the second housing 102 are separated from the tails of the first tab 30 and the second tab 40. The first housing 101 includes a first housing region 101a and a second housing region 101b that are connected to each other. Three sides of the second housing region 101b are surrounded by the first housing region 101a. The second housing 102 includes a third housing region 102a and a fourth housing region 102b that are connected to each other. Three sides of the fourth housing region 102b are surrounded by the third housing region 102a. The housing 10 is formed by sealing the first housing 101 and the second housing 102. Specifically, a first recess 1010 is provided in the second housing region 101b of the first housing 101, and a second recess 1020 is provided in the fourth housing region 102b of the second housing 102. In this way, when the first housing 101 and the second housing 102 are sealed, the first housing region 101a and the third housing region 102a are connected to form the first section 11a, the second section 12a, and the third section 11b. The second housing region 101b and the fourth housing region 102b together constitute a main body 13 that houses the electrode assembly 20. Of course, in other embodiments, the second housing 102 may have a flat plate structure. After the first housing 101 and the second housing 102 are sealed, the first recess 1010 is closed by the fourth housing region 102b of the second housing 102 to form the main body 13.

[0049] The first housing 101 and the second housing 102 may be formed by folding a single sealing film, that is, the materials of the first housing 101 and the second housing 102 are both multi-layer sheets. As shown in FIG. 5, the first housing 101 may have a first protective layer 1011, a first metal layer 1012, and a first polymer layer 1013, which are laminated in this order. The first polymer layer 1013 is closer to the electrode assembly 20 than the first protective layer 1011. The material of the first protective layer 1011 may be a polymer resin, which protects the first metal layer 1012 and reduces the risk of the first metal layer 1012 being damaged by an external force, while delaying the penetration of air from the external environment, thereby maintaining an environment in which the inside of the electrochemical device 100 operates normally. In some embodiments, the material of the first protective layer 1011 may be at least one selected from ethylene terephthalate, polybutylene terephthalate, polyvinylidene fluoride, polytetrafluoroethylene, polypropylene, polyamide, and polyimide. The thickness of the first protective layer 1011 may be in the range of 15 to 35 μm. The first metal layer 1012 can be used to delay the penetration of moisture into the external environment and reduce damage to the electrode assembly 20 caused by external forces. In some embodiments, the first metal layer 1012 is an aluminum foil layer or a steel foil layer. The thickness of the first metal layer 1012 may be in the range of 20 μm to 120 μm. The first polymer layer 1013 has a property of being heated and melted, and can be used for sealing, and can reduce the risk of the multilayer sheet being dissolved or swollen by the organic solvent in the electrolyte. The first polymer layer 1013 is also used to reduce the risk of the electrolyte in the electrolyte contacting the first metal layer 1012 and corroding the metal layer. In some embodiments, the first polymer layer 1013 includes a polymer material and is at least one polymer material selected from polypropylene, propylene copolymer, polyethylene, and polymethyl methacrylate. The thickness of the first polymer layer 1013 may be in the range of 10 μm to 40 μm. In some embodiments, the first housing 101 may further include a first adhesive layer (not shown) and a second adhesive layer (not shown) that are provided between the first protective layer 1011 and the first metal layer 1012 and can bond the first protective layer 1011 and the first metal layer 1012.The second adhesive layer is disposed between the first metal layer 1012 and the first polymer layer 1013 and can be used to adhere the first metal layer 1012 and the first polymer layer 1013 together.

[0050] 6, second housing 102 may include second protective layer 1021, second metal layer 1022, and second polymer layer 1023, which are laminated in this order. When first housing 101 and second housing 102 are obtained by folding one sealing film, the materials of second protective layer 1021, second metal layer 1022, and second polymer layer 1023 are the same as the materials of first protective layer 1011, first metal layer 1012, and first polymer layer 1013, respectively.

[0051] As shown in Figs. 5 and 6, when preparing the housing 10, the first polymer layer 1013 and the second polymer layer 1023 are melted and bonded to each other by the head of the sealing device while applying a certain temperature and pressure to the edges of the first housing 101 and the second housing 102, thereby obtaining the first colloid 110 (shown in Fig. 3). The first colloid 110 is located in the first part 11a. Here, referring to Figs. 3, 11 and 12 together, the first polymer layer 1013 and the second polymer layer 1023 are located not only in the first part 11a but also in the main body part 13, and the first polymer layer 1013 and the second polymer layer 1023 are provided apart from each other in the main body part 13, i.e., are not bonded to each other. Therefore, the first colloid 110 in the present application means a portion in the first part 11a where the first polymer layer 1013 and the second polymer layer 1023 are melted and bonded to each other. The area where the first polymer layer 1013 and the second polymer layer 1023 are separated and not bonded is not included in the first colloid 110. For ease of distinction, in Figs. 11 and 12, the first colloid 110 and the unbonded first polymer layer 1013 and second polymer layer 1023 are shown in different filling manners. However, this does not mean that the first colloid 110 and the unbonded first polymer layer 1013 and second polymer layer 1023 are made of different polymers, and there is no significant limit between them. Since the first part 11a melts to form the first colloid 110, the main body part 13 that houses the electrode assembly 20 can be blocked in the third direction D3, reducing the risk of liquid leakage.

[0052] When the housing 10 further includes the second portion 12a and the third portion 11b, the second portion 12a is provided with a second colloid (not shown) in which the first polymer layer 1013 and the second polymer layer 1023 are melted and bonded together. The second portion 12a can close the main body portion 13 in the first direction D1, reducing the risk of liquid leakage. When the first insulating adhesive 300 and the second insulating adhesive 400 are provided, the first insulating adhesive 300 is also used to reduce the risk of a short circuit occurring between the first tab 30 and the first metal layer 1012 or the second metal layer 1022. Then, during sealing, the first insulating adhesive 300 melts and bonds to the first polymer layer 1013 and the second polymer layer 1023, reducing the risk of liquid leakage. Similarly, the second insulating adhesive 400 is also used to reduce the risk of short circuit between the second tab 40 and the first metal layer 1012 or the second metal layer 1022, and melts and bonds with the first polymer layer 1013 and the second polymer layer 1023 during sealing, reducing the risk of liquid leakage. The third portion 101b may be provided with a third colloid (not shown) in which the first polymer layer 1013 and the second polymer layer 1023 are melted and bonded to each other.

[0053] As shown in FIG. 10, in another embodiment, the housing 10 does not include the third portion 11b. In addition to the first portion 11a and the second portion 12a, the housing 10 further includes a fourth portion 12b connected to the second end wall 135. In this case, the first tab 30 and the second tab 40 may both protrude from the second portion 12a. Alternatively, the first tab 30 and the second tab 40 may both protrude from the fourth portion 12b. Alternatively, the first tab 30 protrudes from the second portion 12a, and the second tab 40 protrudes from the fourth portion 12b. In this case, before sealing, the bending points of the first housing 101 and the second housing 102 are located on the second side wall 133b facing the first portion 11a.

[0054] In some other embodiments, before sealing, the first housing 101 and the second housing 102 are not obtained by folding one sealing film, but are two sealing films independent of each other. By sealing four edges of the two sealing films, the first part 11a, the second part 12a, the third part 11b, and the fourth part 12b are obtained at the same time.

[0055] 7 to 9, after sealing, the first part 11a is folded twice to form a double hemmed structure. FIGS. 7 and 8 show the configuration before the first part 11a is folded, and the extending direction of the first part 11a is approximately parallel to the third direction D3. FIG. 9 shows the configuration in which the first part is folded for the first time, and FIG. 3 shows the configuration in which the first part is folded for the second time. For example, as shown in FIG. 8, a part of the first part 11a is folded for the first time to protect the metal layer exposed from the edge of the first part 11a, and the risk of short circuiting with the outside world after the metal layer is exposed is reduced to increase safety. Then, as shown in FIG. 3, the first part 11a is folded for the second time toward the first side wall 133a. For this reason, as shown in FIG. 3, the first part 11a includes a first seal edge 111 and a second seal edge 112. The first seal edge 111 connects the first side wall 133a and the second wall 132. The second seal edge 112 connects the first seal edge 111 and is provided between the first seal edge 111 and the first side wall 133a. The second seal edge 112 is formed by a first folding, and the first seal edge 111 is formed by a second folding. Alternatively, in another embodiment, the folding order of the double hemming structure may be such that the first portion 11a is first folded to the first side wall 133a, and then a part of the first portion 11a is folded a second time to protect the metal layer exposed from the edge of the first portion 11a. The order of the two foldings may be selected according to circumstances and is not particularly limited in this application.

[0056] As shown in FIG. 11 and FIG. 12, in a cross section perpendicular to the first direction D1 (i.e., a plane on which the cross section is located extends in the second direction D2 and the third direction D3), there is a first connection point A between the first seal edge 111 and the first side wall 133a. Here, the first connection point A is a connection point between an outer surface of the first seal edge 111 facing the first side wall 133a and an outer surface of the first side wall 133a. The first side wall 133a starts from the first connection point A and extends outward along the contour of the first side wall 133a to form a first straight line X1, and the first straight line X1 and the second wall 132 intersect at an intersection 1320. Here, the intersection 1320 is an intersection point between the first straight line X1 and the outer surface of the second wall 132. In the present application, the first straight line X1 is the boundary line between the first portion 11a and the main body portion 13 in a cross section perpendicular to the first direction D1. Therefore, even in a cross section perpendicular to the first direction D1, the intersection point 1320 is the boundary point between the second wall 132 and another outer surface away from the first side wall 133a of the first seal edge 111. The first colloid 110 is located in a space formed by being surrounded by the first straight line X1 and the first portion 11a. When sealing the first portion 11a, the first polymer layer 1013 and the second polymer layer 1023 at the sealing position melt to form the first colloid 110, and the first colloid 110 is pushed out to a position where one of the pressures is smaller (i.e., pushed out from the second seal edge 112 to the first seal edge 111). Therefore, in a cross section perpendicular to the first direction D1, the first colloid 110 may form a corner 110a (i.e., a bump), and the corner 110a protrudes toward the inside of the main body 13. For example, when the first colloid 110 is pushed to one side and forms a curve protruding toward the inside of the main body 13 in a cross section perpendicular to the first direction D1, the corner 110a is a position of the edge of the first colloid 110 where the shape is most protruding. For example, when the first colloid 110 forms an edge similar to a circular arc, the corner 110a may be a point of the edge of the first colloid 110 with the smallest radius of curvature. As shown in FIG. 11, in some embodiments, in a cross section perpendicular to the first direction D1, the edge of the first colloid 110 (i.e., the corner 110a) is located away from the first straight line X1.12, in some other embodiments, the edge of the first colloid 110 (i.e., at the corner point 110a) may be tangent to the first straight line X1. In some embodiments, when the first side wall 133a is an arc surface, the first straight line X1 is a tangent line passing through the first connection point A.

[0057] As shown in FIG. 13, when the first housing and the second housing are sealed to form the first part, the side wall changes in the extension direction at the part where the side wall is connected to the first part (i.e., the first connection point A), and after bending the first part, the degree of change in the extension direction at the first connection point A becomes even greater, and the first connection point A protrudes toward the inside of the main body part. Therefore, stress concentration is likely to occur at the first connection point A during mechanical abuse, and there is a risk of the housing bursting, causing liquid leakage, and shortening the life of the electrochemical device. And, since the first colloid formed after melting and bonding has a high hardness and the first connection point A is close to the first colloid, the flexibility of the housing near the first connection point A is reduced. This makes it easier for stress concentration to occur at the first connection point A, which in turn causes fatigue damage and the housing bursts. In addition, the first colloids are more likely to strike the electrode assembly, and stress is concentrated at the contact point between the two, causing the electrode assembly to break or the cycle performance to deteriorate (stress is concentrated at the contact point, causing the active material layer to fall off the collector surface, resulting in a micro-short circuit and increased self-discharge). In the present application, by limiting the range of the first colloids 110, the impact force of the first colloids 110 against the first connection point A during mechanical abuse is reduced, and the risk of rupture at the first connection point A is further reduced, improving the mechanical strength of the first portion 11a. In addition, this is advantageous in reducing the risk of the first colloids 110 striking the electrode assembly 20 during mechanical abuse, and improving the cycle performance and lifespan of the electrochemical device 100. In addition, by limiting the range of the first colloids 110, the problem of the first colloids 110 protruding during sealing affecting the sinking of the electrode assembly 20 is also improved.

[0058] As shown in FIG. 14 and FIG. 16, in another embodiment, when the edge of the first colloid 110 is disposed away from the first straight line X1, a straight line extending through the first connection point A in the second direction D2 is defined as a second straight line X2, and the second straight line X2 intersects with the outer surface of the first portion 11a away from the first side wall 133a at an intersection point 1100. The first colloid 110 is located in a space formed by the second straight line X2 and the first portion 11a. As shown in FIG. 14, in some embodiments, the edge of the first colloid 110 is disposed away from the second straight line X2. As shown in FIG. 16, in some other embodiments, the edge of the first colloid 110 may be in contact with the second straight line X2. By defining the range of the first colloid 110, the impact force of the first colloid 110 against the first connection point A during mechanical abuse is further reduced, and the risk of the first colloid 110 hitting the electrode assembly 20 is also further reduced. Furthermore, since the first colloid 110 does not exceed the second straight line X2, a buffer space for containing the electrolyte is formed between the first straight line X1, the second straight line X2, and the second wall 132. This buffer space therefore improves the situation in which the electrolyte directly hits the first colloid 110 during mechanical abuse, reduces the risk of the electrolyte breaking through the first portion 11a and causing leakage, and enhances safety.

[0059] 3, in some embodiments, the sum of the length L1 of the first seal edge 111 and the length L2 of the second seal edge 112 in the second direction D2 is defined as L, and the thickness of the electrode assembly 20 in the second direction D2 is H, where 3 / 4H≦L≦5 / 4H. In the present application, by setting the L value to satisfy the above relationship, the sealing strength of the first part 11a is improved when the L value is too small, reducing the risk that the first part 11a will be broken by the electrode assembly 20 or the electrolyte, while also improving the problems of increased costs and reduced energy density when the L value is too large.

[0060] In the present application, the dimensions, such as the thickness H of the electrode assembly 20, the length L1 of the first seal edge 111, and the length L2 of the second seal edge 112, can be measured at multiple sample points and averaged.

[0061] As shown in FIGS. 11, 12, 14, and 16, in some embodiments, the second seal edge 112 includes a first end 1121 connecting the first seal edge 111 and a second end 1122 provided opposite to the first end 1121. Here, the first end 1121 is a bent portion between the second seal edge 112 and the first seal edge 111. The second end 1122 is an end of the first portion 11a away from the first sidewall 133a, that is, a portion where the first metal layer 1012 and the second metal layer 1022 are exposed in the first portion 11a, and the position of the second end 1122 reflects the length of the second seal edge 112 in the second direction D2. The electrode assembly 20 has a first surface P1 perpendicular to the second direction D2, and the first surface P1 is an imaginary surface. In the second direction D2, the thicknesses of the electrode assembly 20 located on both sides of the first surface P1 are the same. That is, the first surface P1 is a central surface of the electrode assembly 20 in the second direction D2. The first surface P1 is located between the second end 1122 and the second wall 132. By defining the position of the second end 1122 of the second seal edge 112, the risk that the first portion 11a will easily separate from the first side wall 133a is reduced when the position of the second end 1122 is low (i.e., the length of the second seal edge 112 is large).

[0062] As shown in Figures 11, 12, 14 and 16, in some embodiments, when sealing the first part 11a, the first polymer layer 1013 and the second polymer layer 1023 at the sealing position melt to form the first colloid 110, and the first colloid 110 is extruded to one side where the pressure is smaller to form a colloid-over region having a thickness greater than that of the main sealing region. That is, the first seal edge 111 includes a first region 1111 (i.e., a colloid-over region) where the first colloid 110 is extruded to one side to form a colloid-over region, and a second region 1112 (i.e., a main sealing region) formed by directly contacting the sealing head and being directly heat-pressed by the sealing head. The second region 1112 is connected between the first region 1111 and the second seal edge 112. The sealing strength of the first region 1111 is smaller than that of the second region 1112. Generally, the length of the second region 1112 is shorter than the length of the first region 1111 along the extension direction from the first sealing edge 111 to the second sealing edge 112. In some embodiments, the thickness H1 of the first region 1111 may gradually decrease (i.e., H1 is not a constant value) and the thickness H2 of the second region 1112 may gradually decrease (i.e., H2 is not a constant value) along the extension direction from the first sealing edge 111 to the second sealing edge 112, and the thickness H1 of the first region 1111 is greater than the thickness H2 of the second region 1112 (i.e., the content of the first colloid 110 in the first region 1111 per unit length is greater than the content of the first colloid 110 in the second region 1112 per unit length). In some other embodiments, the first region 1111 may be a region that comes into contact with a sealing head during hot pressing, and the present application is not limited thereto. For example, the head is an irregular head, and the distance between the upper and lower heads for sealing the first region 1111 is relatively large, and the upper and lower heads are directly hot-pressed to form the first region 1111 having a relatively large thickness.

[0063] In some specific embodiments, the change in thickness of the second region 1112 is 10 μm or less and the change in thickness of the first region 1111 is more than 10 μm along the extending direction from the second sealing edge 112 to the first sealing edge 111. That is, the change in thickness of the second region 1112 is relatively gentle, and the change in thickness of the first region 1111 is larger than that of the second region 1112. Here, the change in thickness is the value of the increase in thickness at both ends of the first region 1111 or the second region 1112 that are provided opposite to each other along the extending direction from the second sealing edge 112 to the first sealing edge 111. The following process can be adopted to identify the boundary between the first region 1111 and the second region 1112. A cross-sectional view of the electrochemical device 100 is obtained, and a sampling point is selected on the first sealing edge 111 at a predetermined interval starting from the first end 1121 in the cross-sectional view, and the thickness of the first sealing edge 111 at the sampling point is identified. If the difference in thickness between the sampling point and the first end 1121 is less than 10 μm, the sampling point is determined to belong to the second region 1112. Then, the next sampling point is selected at a predetermined interval until the difference in thickness between the first seal edge 111 at the selected sampling point and the first end 1121 becomes 10 μm. In this case, the range from the first end 1121 to the selected sampling point becomes the second region 1112, and the remaining range of the first seal edge 111 becomes the first region 1111.

[0064] When sealing the first portion 11a, the first polymer layer 1013 and the second polymer layer 1023 at the sealing position may melt to form the first colloid 110, and then the first colloid 110 may be pushed out to the second end 1122 of the second seal edge 112. That is, the second seal edge 112 may also form a colloid-over region with a large thickness at the second end 1122. The colloid-over region of the first seal edge 111 and the colloid-over region of the second seal edge 112 are provided separately. In determining the ranges of the first region 1111 and the second region 1112 described above, the colloid-over region of the second seal edge 112 is not taken into consideration.

[0065] As shown in FIG. 11, FIG. 12, FIG. 14, and FIG. 16, in a cross section perpendicular to the first direction D1, a second connection point B is provided between the first region 1111 and the second region 1112, the second connection point B being selected from the boundary line between the first region 1111 and the second region 1112. The position of the second connection point B reflects the length of the first region 1111 and the second region 1112 in the second direction D2. In some embodiments, the second connection point B is located between the first surface P1 and the second wall 132. By defining the position of the second connection point B, the dimension of the first region 1111 in the second direction D2 is reduced, and the dimension of the second region 1112 having a higher sealing strength in the second direction D2 is increased, thereby improving the sealing strength of the first portion 11a. Therefore, the risk of leakage due to the first portion 11a being broken by the electrolyte is reduced, and safety is improved.

[0066] In some embodiments, in a cross section perpendicular to the first direction D1, a third connection point C is provided between the second region 1112 and the second seal edge 112. The third connection point C is a folding point between the second region 1112 and the first region 1111, i.e., an intersection point of the first end 1111 in the cross section. The position of the third connection point C also reflects the length of the second seal edge 112 in the second direction D2. The electrode assembly 20 further has a second surface P2 perpendicular to the second direction D2, and the second surface P2 is an imaginary surface. In the second direction D2, the thickness of the electrode assembly 20 located between the second surface P2 and the second wall 132 is 3 / 4 of the total thickness of the electrode assembly 20. In the second direction D2, the third connection point C is located between the second surface P2 and the second wall 132. That is, in the second direction D2, the third connection point C is less than 3 / 4 of the total thickness of the electrode assembly 20, and therefore, when the third connection point C is high (i.e., the length of the second seal edge 112 is large), the risk that the first portion 11a will easily separate from the first side wall 133a is reduced. As shown in FIG. 14, when the edge of the first colloid 110 is located away from the first straight line X1, the first seal edge 111 further includes a third region 1113, and the first region 1111 is connected between the second region 1112 and the third region 1113. The first polymer layer 1013 in the third region 1113 is not bonded to the second polymer layer 1023, that is, the first colloid 110 formed by the first polymer layer 1013 and the second polymer layer 1023 melting with each other is not located in the third region 1113. At this time, the corner point 110a protrudes toward the third region 1113. Please refer to FIG. 15A for detailed positions of the first region 1111 and the third region 1113.

[0067] As shown in FIG. 14 and FIG. 15A, a straight line passing through the first connection point A and extending in the second direction D2 is defined as a second straight line X2, and the third region 113 is provided on one side of the second straight line X2 that is away from the electrode assembly 20. By disposing the third region 1113, the impact force of the first colloid 110 on the first connection point A during mechanical abuse is further reduced, and the risk of the first colloid 110 hitting the electrode assembly 20 is also further reduced. In addition, the third layer 1113 forms a buffer space that contains the electrolyte. Therefore, this buffer space improves the situation where the electrolyte directly hits the first colloid 110 during mechanical abuse, reduces the risk of the first part 11a being broken by the electrolyte and leaking, and can improve safety.

[0068] Referring to FIG. 15B, in some embodiments, in a cross section perpendicular to the first direction D1, when the area of ​​the portion where the third region 1113 is provided between the first metal layer 1012 and the second metal layer 1022 is A1, and the area of ​​the portion where the first region 1111 is provided between the first metal layer 1012 and the second metal layer 1022 is A2, 0.5≦A1 / A2≦3. In the present application, by setting A1 / A2 to satisfy the above relationship, the problem that the first part 11a is difficult to bend at the connection part with the first side wall 133a when the ratio of A1 to A2 is too small (i.e., the colloid over region is large) is improved, and the dimension of the electrochemical device in the third direction D3 after bending is reduced, and the volume energy density is improved. In addition, when the ratio of A1 to A2 is too large, the risk of the sealing strength of the first part 11a decreasing is also reduced. Alternatively, in a preferred embodiment, 1≦A1 / A2≦2. Within this range, the first portion 11a has high sealing strength and is easily bent at the connection with the first side wall 133a. Here, A1 can be measured by an imaging method, and the measurement step includes the following steps. A cross section of the first portion 11a is cut in a cross section perpendicular to the first direction D1, and an image including the above-mentioned cross section in the first direction D1 is collected as a first image. A second image is collected as an image serving as a reference target whose area is known to be S0. The number n1 of pixel points corresponding to the third region 1113 in the first image is calculated, and the number n0 of pixel points corresponding to the reference target in the second image is calculated. The area A1 of the third region 1113 is calculated based on the area A0, the number n1, and the number n0. That is, A1=(S0×n0) / n1. Similarly, A2 can also be measured by an imaging method.

[0069] 14, in some embodiments, in a cross section perpendicular to the first direction D1, the third line X3 passes through the corner point 110a and is parallel to the second line X2. The third line X3 intersects with the boundary between the first metal layer 1012 and the first polymer layer 1013 of the first seal edge 111 at a first intersection J1, and the third line X3 intersects with the boundary between the second metal layer 1022 and the second polymer layer 1023 of the first seal edge 111 at a second intersection J2. If the distance between the first intersection point J1 and the second intersection point J2 is L3 (indicating the maximum value of the thickness H1 of the first region 1111 along the extension direction from the first seal edge 111 to the second seal edge 112), and the distance between the corner point 110a and the boundary line between the first region 1111 and the second region 1112 in the second direction D2 is L4 (indicating the length of the first region 1111 in the second direction D2), then 0.1≦L3 / L4≦0.6. In some embodiments, in a cross section perpendicular to the first direction D1, the distances of the corner point 110a from both sides of the first seal edge 111 may be the same. In this case, the third straight line X3 is perpendicular to either side of the first seal edge 111. In the present application, by setting L3 / L4 to satisfy the above relationship, the problem of insufficient heat sealing of the second region 1112 when the ratio of L3 to L4 is too small (i.e., the thickness of the first region 1111 is small) or when the ratio of L3 to L4 is too large (i.e., the length of the first region 1111 is small) is improved, and the sealing strength of the first portion 11a is improved. Alternatively, in a preferred embodiment, 0.3≦L3 / L4≦0.5. Within this range, the first portion 11a has high sealing strength. However, L3 and L4 can be measured by a direct measurement method, and the measurement step includes the following steps. After cutting out a cross section of the first portion 11a perpendicular to the first direction D1 and marking L3 and L4 on the cross section by the above-mentioned method, the values ​​of L3 and L4 are directly measured with a caliper or other suitable measuring tool, or an image of the cross section is taken and measured within the image.

[0070] As shown in FIG. 3, in some embodiments, the electrochemical device 100 further includes a first adhesive 50. The first adhesive 50 bonds the second seal edge 112 to the outer surface of the first side wall 133a, thereby fixing the second seal edge 112 to the first side wall 133a, and further reducing the risk of the first portion 11a being separated. However, the first adhesive 50 may be a double-sided tape or a hot melt, and the first adhesive 50 is provided continuously. The material of the adhesive layer in the double-sided tape may be one or more selected from acrylic ester, polyurethane, rubber, and silica gel, and the hot melt may be one or more selected from polyolefin-based hot melt, polyurethane-based hot melt, ethylene and its copolymer-based hot melt, polyester-based hot melt, polyamide-based hot melt, styrene and its block copolymer-based hot melt, and the present application is not particularly limited.

[0071] The electrochemical device 100 may further include a second adhesive 60. The second adhesive 60 at least bonds the inner surface of the first side wall 133a and the electrode assembly 20, thereby fixing the electrode assembly 20 in the housing 10. In this way, the risk of the electrode assembly 20 moving wildly in the housing 10 in the third direction D3 when mechanical abuse occurs can be reduced, and thus the impact of the electrode assembly 20 on the first part 11a of the housing 10 can be reduced to improve safety. Note that the second adhesive 60 may be a double-sided tape or a hot melt. As shown in FIG. 3, in some specific embodiments, the number of the second adhesives 60 is two, and each adhesives the inner surface of the first side wall 133a and the inner surface of the second side wall 133b.

[0072] The electrochemical device 100 may further include a third adhesive 70. The third adhesive 70 bonds the electrode assembly 20 to at least one of the inner surfaces of the first wall 131 or the second wall 132. In this way, the risk of the electrode assembly 20 moving wildly in the housing 10 in the second direction D2 when mechanical abuse occurs can be reduced, and thus the impact of the electrode assembly 20 on the second part 12a of the housing 10 can be reduced to improve safety. The third adhesive 70 may be a double-sided tape or a hot melt. As shown in FIG. 3, in some specific embodiments, the number of the third adhesives 70 is two, and the inner surface of the first wall 131 and the inner surface of the second wall 132 are bonded to each other.

[0073] 2, in some embodiments, the second portion 12a is closer to the second wall 132 than the first wall 131 in the second direction D2. In the second direction D2, the first end wall includes a first end surface 1341 and a second end surface 1342 located on either side of the first tab 30, the first end surface 1341 connecting the second portion 12a to the first wall 131, and the second end surface 1342 connecting the second portion 12a to the second wall 132. That is, the first end surface 1341 is a deep pit surface, and the second end surface 1342 is a shallow pit surface.

[0074] Furthermore, the electrochemical device 100 may include a fourth adhesive 80 that bonds the first end surface 1341 and the edge of the second part 12a. The fourth adhesive 80 can cover the metal layer exposed from the edge of the second part 12a, thereby improving safety. The third adhesive 70 does not cover the entire edge of the second part 12a so that the first tab 30 and the second tab 40 protrude from the edge of the second part 12a. The fourth adhesive 80 may be a single-sided tape, a double-sided tape, or a hot melt. The material of the adhesive layer in the single-sided tape may be one or more types selected from acrylate, polyurethane, rubber, and silica gel, and is not particularly limited in the present application.

[0075] As shown in FIG. 3, in some embodiments, the first current collector 210 has a first surface 2101 and a second surface 2102 facing each other. When the electrode assembly 20 has a wound structure, the outermost surface of the electrode assembly 20 is the first surface 2101. Therefore, even if the first colloid 110 impacts the electrode assembly 20 during mechanical abuse, the first surface 2101 is the outer surface, so that when an active material is provided on the outer surface of the electrode assembly 20, the active material is prevented from falling off. Meanwhile, the first current collector 210 can increase the hardness of the electrode assembly 20 and serves to protect the electrode assembly 20.

[0076] Referring to FIG. 17, another embodiment of the present disclosure further provides an electrochemical device 200. The electrochemical device 200 is different from the above-mentioned electrochemical device 100 in that the outermost periphery of the electrode assembly 20 is a separation membrane 23. That is, in this embodiment, the separation membrane 23 is extended and finished with the separation membrane 23. The separation membrane 23 increases the frictional force between the electrode assembly 20 and the housing 10, and increases the adhesive force between the electrode assembly 20 and the first adhesive 50 or the second adhesive 60, so that the electrode assembly 20 can be more suitably fixed in the housing 10. In addition, the separation membrane 23 can form a protective layer, which can avoid the risk of short circuit due to wear of the electrode sheet inside the separation membrane 23 in this portion, and can increase the resistance of the electrode assembly 20 to mechanical shock.

[0077] The electrochemical device 100 (or electrochemical device 200) of the present application includes all devices that cause electrochemical reactions. Specifically, the electrochemical device 100 includes all primary batteries, secondary batteries, fuel cells, solar cells, and capacitors (e.g., supercapacitors). The electrochemical device 100 may be a lithium secondary battery, including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, and a lithium ion polymer secondary battery.

[0078] Referring to FIG. 18, one embodiment of the present application provides an electronic device 1 including an electrochemical device 100 (or an electrochemical device 200).

[0079] The electrochemical device 100 of the present application is applicable to electronic devices 1 in various fields. The electronic devices 1 of the present application include, but are not limited to, notebook computers, pen-input computers, mobile personal computers, electronic book players, mobile phones, portable facsimiles, portable copiers, portable printers, headset stereo earphones, video recorders, liquid crystal televisions, portable cleaners, portable CD players, mini discs, transceivers, electronic organizers, calculators, memory cards, portable recorders, radios, backup power sources, motors, automobiles, motorcycles, power-assisted bicycles, bicycles, lighting equipment, toys, game devices, watches, power tools, strobes, cameras, large household storage batteries, and lithium ion capacitors.

[0080] The present application will be described in detail below with reference to examples and comparative examples. Here, the electrochemical device is taken as an example of a soft-pack battery, and the present application will be described by combining specific manufacturing methods and test methods. Those skilled in the art should understand that the manufacturing methods described in the present application are merely examples, and any other suitable manufacturing methods are within the scope of the present application.

[0081] Example 1 (1) Preparation of negative electrode sheet: Mix the negative electrode active materials artificial graphite, conductive carbon black (SuperP), and styrene butadiene rubber (SBR) in a weight ratio of 96:1.5:2.5, add deionized water as a solvent, prepare a slurry with a solid content of 70% by weight, and stir evenly. Apply the slurry evenly to one surface of a negative electrode current collector copper foil with a thickness of 10 μm, and dry at 110 ° C to obtain a negative electrode sheet with a coating thickness of 150 μm on one side coated with a negative electrode active material layer. Repeat the above steps on the other side of this negative electrode sheet to obtain a negative electrode sheet with a negative electrode active material layer coated on both sides. (2) Preparation of positive electrode sheet: Positive electrode active material lithium cobalt oxide (LiCoO2), conductive carbon black (SuperP), and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75% by weight, which is then stirred uniformly. The slurry is uniformly applied to one surface of a positive electrode current collector aluminum foil with a thickness of 12 μm, and dried at 90 ° C to obtain a positive electrode sheet with a positive electrode active material layer thickness of 100 μm. The above process is repeated on the other surface of the positive electrode current collector aluminum foil to obtain a positive electrode sheet with a positive electrode active material layer applied on both sides. (3) Preparation of electrolyte: In a dry argon atmosphere, first, the organic solvents ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a mass ratio of EC; EMC:DEC = 30:50:20, and then the lithium salt lithium hexafluorophosphate (LiPF6) is added and dissolved in the organic solvent and mixed uniformly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L. (4) Preparation of electrode assembly: A separator, a double-sided coated negative electrode sheet, a separator, and a double-sided coated positive electrode sheet are sequentially stacked and wound. The thickness of the electrode assembly is H. The electrode assembly is composed of one positive electrode tab and one negative electrode tab, the positive electrode tab being aluminum (Al) and the negative electrode tab being nickel (Ni), the two tabs being arranged side by side, and the separator is a polyethylene (PE) film having a thickness of 15 μm. (5) Assembling the electrode assembly: A punched aluminum preparation (thickness 150 μm) is placed in an assembly jig with the pit facing up, the electrode assembly is placed in the pit with the separation membrane surface facing up, and tab rubbers are attached to the areas on the edges of the aluminum preparation that correspond to the tabs of the electrode assembly. (6) Injection and sealing: Inject electrolyte into the pits of the aluminum mold, and pull out all the tabs of the electrode assembly from the aluminum mold. Press the edges of the aluminum mold using the head of the sealing device to form the first part. The sum L of the lengths of the first and second seal edges of the first part is equal to the thickness H of the electrode assembly. (7) Folding: The first portion is folded twice to form a double hemmed structure to obtain a battery. When the cross section of the battery of Example 1 is cut out in a cross section direction perpendicular to the first direction D1 and measured, the area A1 of the third region and the area A2 of the first region are A1 / A2=0.4. The distance between the first intersection and the second intersection is L3, and the distance between the corner point and the boundary line between the first region and the second region is L4, so that L3 / L4=0.3. The position of the second connection point between the first region and the second region is below the first surface.

[0082] Examples 2 to 7 and Comparative Example 1 The differences from Example 1 are the range of the first colloid, the relationship between L and H, and / or the position of the second connection point. Here, the range of the first colloid can be adjusted by controlling the temperature and pressure of the head. L is adjusted by adjusting the width of the head, and thus the relationship between L and H is adjusted. The position of the second connection point is adjusted by adjusting the position of the folding point between the first seal edge and the second seal edge.

[0083] Then, for the batteries of each Example and Comparative Example, a slight drop test, a drop test, a roll test, a sealing strength test, and an energy density test are performed. Ten batteries are taken from each Example and Comparative Example and tested, and the corresponding test results are recorded in Table 1.

[0084] Micro-tumble test steps: 1) Discharge the battery to 0% SOC (State of Charge) at 0.2C DC in an environmental condition of 25°C. Leave to stand for 5 minutes. Charge again to 50% SOC at 0.5C constant current, then charge to 0.05C at constant voltage. Leave to stand for 5 minutes and measure the battery voltage and internal resistance. 2) Place the battery in a fixture box, and use an automatic drop device to drop the battery from a position of 10cm onto a steel plate so that it lands on the bottom, left side, right side, front, back, and top of the battery in that order, for a total of 100 rotations, or 600 rotations, as one cycle, for a total of 3 cycles. 3) Furthermore, perform a micro-tumble test on the front and back, dropping it for a total of 500 rotations, or 1000 rotations, for a total of 3 cycles. 4) After the slight drop test is completed, place the battery in an environment with a temperature of (60±3)℃ and a relative humidity of 90% and leave it for 14 days. After that, check for damage and leakage at the first connection point and record the battery voltage and internal resistance. If the voltage drop is less than 0.2V and no rupture occurs at the first connection point, the battery is considered to have passed the slight drop test.

[0085] Drop test steps: 1) Place the battery in a jig box, change the drop height to 1.8m, and drop the jig box with the battery onto a steel plate from 1.8m above the jig box using the automatic drop equipment, so that the jig box lands on the top, bottom, left side, right side, front, back, and top of the jig box in order, for a total of three rotations, i.e., 18 rotations. 2) After each rotation, measure the battery voltage. If the battery ignites or leaks, stop dropping it. If not, continue the test for a total of three rotations. 3) After the drop is complete, disassemble the battery. If the first part does not come apart, the first connection point does not explode, and there is no dent on the surface of the electrode assembly, it is determined that the battery has passed the drop test.

[0086] Drum test steps: 1) Charge the battery to 100% under 25°C environmental conditions, and the battery voltage is 4.4V. 2) Place the battery in the jig box, attach the back of the battery to the jig with adhesive tape, and then tighten the screws on the jig. Place the jig with the battery in it on the drum tester to perform the test, and leave it for 24 hours after the test is completed. However, the drum speed is 7 rotations / min, the drop height is 1m, and the battery rotates a total of 1000 times. If the battery does not leak, catch fire, explode, or show any other symptoms after the drum test, the battery is deemed to have passed the drum test.

[0087] [Table 1]

[0088] In Table 1, a slight drop test pass rate of 0 / 10 indicates that 0 of the 10 tested batteries passed the test. A slight drop pass rate of 10 / 10 indicates that 10 of the 10 tested batteries passed the test. The meanings of the other proportional values ​​can be inferred in this manner.

[0089] From the data in Table 1, it can be seen that compared to Comparative Example 1, in Example 1, the first colloid does not exceed the first straight line, so the pass rates in the micro-fall test, fall test, and drum test are high, and safety is also high.

[0090] On the premise that the first colloid does not exceed the first straight line, the L value and the position of the second connection point both have further influence on the test results. Compared with Examples 1, 3, and 4, the L value of Example 2 is small, and the L value of Example 5 is large, which does not meet 3 / 4H≦L≦5 / 4H, so the passing rate of the connection test is relatively reduced. Compared with Example 1, the second connection point of Example 6 is above the first surface, so the passing rate of the drop test is relatively reduced.

[0091] Assuming that the first colloid does not exceed the first line, the first colloid in Example 7 does not exceed the second line compared to Example 1, and therefore the passing rate of the drop test is relatively improved.

[0092] Examples 8 to 22 The difference from Example 1 is the values ​​of the A1 / A2 and L3 / L4 ratios. The A1 / A2 and L3 / L4 ratios can be adjusted by adjusting the structure of the colloid over tank of the head.

[0093] Then, the batteries of each embodiment are subjected to a sealing strength test and an energy density test, and the corresponding test results are shown in Table 2.

[0094] Steps of seal strength test: 1) Remove the first part from the housing to obtain sample 1. 2) Cut sample 1 into a test strip with a width L of 8 mm, which completely preserves the entire sealing area and the packaging cases on both sides of the sealing area are intact to obtain sample 2. 3) Use a high-strength steel tension machine to tear both sides of the housing at an angle of 180° so that the two layers of the housing are separated from each other within the sealing area. 4) Record the stable tensile force F when the two layers are separated, and calculate the seal strength σ=F / L.

[0095] Energy density test steps: (1) Charge the battery at 25°C from 3.0V to 4.4V at a charge rate of 1C, then discharge it to 3.0V at a discharge rate of 0.1C. Measure the 0.1C discharge capacity. The 0.1C discharge energy density is 0.1C discharge capacity / battery volume.

[0096] [Table 2]

[0097] From the data in Table 2, it can be seen that, compared with Example 1 and Example 15, Examples 8-14 have a high volumetric energy density and a high sealing strength because they satisfy 0.5≦A1 / A2≦3. Compared with Example 16 and Example 22, Examples 17-21 have a high sealing strength because they satisfy 0.1≦L3 / L4≦0.6.

[0098] The above examples are only used to explain the technical aspects of the present application, and do not limit the present application. Although the present application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that the technical aspects of the present application can be modified or substituted with equivalents without departing from the spirit and scope of the technical aspects of the present application. [Explanation of symbols]

[0099] 1 Electronic equipment 10. Cabinet 11a Part 1 11b Part 3 12a Part 2 12b Part 4 13 Main body 20 Electrode assembly 21 First electrode sheet 22 Second electrode sheet 23 Separation membrane 30 First Tab 31 Connection 32 Adapter part 40 Second Tab 50 1st adhesive 60 Second adhesive 70 Third adhesive 80 4th adhesive 100, 200 Electrochemical equipment 101 First cabinet 102 Second cabinet 110 Colloid No. 1 110a corner point 111 First seal edge 112 Second seal edge 131 1st wall 132 Second wall 133a 1st side wall 133b 2nd side wall 134 First End Wall 135 Second End Wall 201 First Segment 202 First bend segment 203 Second Segment 204 Second bend segment 210 First current collector 211 First active material layer 220 Second current collector 300 First Insulation Adhesive 400 Second Insulation Adhesive 1010 First recess 1011 1st protective layer 1012 1st metal layer 1013 First polymer layer 1020 Second recess 1021 Second protective layer 1022 2nd metal layer 1023 2nd polymer layer 1111 First area 1112 Second area 1113 Third area 1121 1st end 1122 2nd end 1341 1st end face 1342 Second end face 2101 1st surface 2102 2nd surface A First connection point B Second connection point C 3rd connection point X1 1st straight line X2 2nd straight line X3 3rd straight line H, H1, H2 thickness P1 first page P2 second page O Winding center axis D Winding direction D1 1st direction D2 2nd direction D3 Third direction L1, L2, L3, L4 lengths 1320, 1100 intersection J1 1st intersection J2 2nd intersection

Claims

1. An electrochemical device comprising a housing, an electrode assembly, and a tab, the housing includes a main body and a first part, the electrode assembly is provided in the main body, and the tab is electrically connected to the electrode assembly and protrudes from the housing; a direction in which the tab protrudes from the electrode assembly is defined as a first direction, a thickness direction of the electrode assembly is defined as a second direction, and a direction perpendicular to the first direction and the second direction is defined as a third direction; In the second direction, the main body portion includes a first wall and a second wall provided opposite to each other, and in the third direction, the main body portion includes a first side wall and a second side wall provided opposite to each other, the first portion includes a first seal edge connecting the first side wall and the second wall, and a second seal edge connecting the first seal edges, the second seal edge being provided between the first seal edge and the first side wall; The housing includes a first housing and a second housing provided opposite to each other, the first housing having a first polymer layer, the second housing having a second polymer layer, the first polymer layer and the second polymer layer being bonded to each other to form a colloid, the colloid being located in a first portion, an electrochemical device characterized in that, in a cross section perpendicular to the first direction, there is a first connection point between the first sealing edge and the first side wall, the first side wall forms a first straight line at the first connection point extending outward along a contour of the first side wall, and the colloid is located within a space formed by the first portion and the first straight line.

2. The electrochemical device according to claim 1, characterized in that a straight line passing through the first connection point and extending along the second direction is defined as a second straight line, and the colloid is located within a space formed by being surrounded by the first portion and the second straight line.

3. 2. The electrochemical device of claim 1, wherein the sum of the length of the first seal edge and the length of the second seal edge in the second direction is L and the thickness of the electrode assembly in the second direction is H, and 3 / 4H≦L≦5 / 4H holds.

4. 2. The electrochemical device of claim 1, wherein the second sealing edge includes a first end connected to the first sealing edge and a second end provided opposite to the first end, the electrode assembly has a first surface perpendicular to the second direction, the thickness of the electrode assembly located on both sides of the first surface in the second direction is the same, and the first surface is located between the second end and the second wall.

5. 2. The electrochemical device of claim 1, wherein the first sealing edge includes a first region and a second region, the second region being connected between the first region and the second sealing edge, and the thickness of the first region is greater than the thickness of the second region.

6. 6. The electrochemical device according to claim 5, wherein in a cross section perpendicular to the first direction, a second connection point is provided between the first region and the second region, the electrode assembly has a first surface perpendicular to the second direction, the thickness of the electrode assembly on both sides of the first surface in the second direction is the same, and the second connection point is located between the first surface and the second wall.

7. 6. The electrochemical device of claim 5, wherein in a cross section perpendicular to the first direction, a third connection point is provided between the second region and the second seal edge, the electrode assembly has a second surface perpendicular to the second direction, a thickness of the electrode assembly located between the second surface and the second wall in the second direction is 3 / 4 of an entire thickness of the electrode assembly, and the third connection point is located between the second surface and the second wall in the second direction.

8. the first seal edge further includes a third region, the first region being connected between the second region and the third region, the first polymer layer in the third region not adhering to the second polymer layer; 2. The electrochemical device according to claim 1, wherein in a cross section perpendicular to the first direction, there is a first connection point between the first sealing edge and the first side wall, and a straight line passing through the first connection point and extending along the second direction is defined as a second straight line, and the third region is provided on one side of the second straight line.

9. The first housing further includes a first metal layer laminated on the first polymer layer, and the second housing further includes a second metal layer laminated on the second polymer layer; In a cross section perpendicular to the first direction, the area of ​​a portion of the third region provided between the first metal layer and the second metal layer is defined as A. １ and the area of ​​the portion of the first region provided between the first metal layer and the second metal layer is A ２ Then, 0.5≦A １ / A ２ 9. The electrochemical device of claim 8, wherein: ≦3.

10. In a cross section perpendicular to the first direction, the colloid in the first region includes a corner point, and the corner point protrudes toward the third region; The first housing further includes a first metal layer laminated on the first polymer layer, and the second housing further includes a second metal layer laminated on the second polymer layer; A third straight line is defined that passes through the corner point and is parallel to the second straight line, the third straight line intersecting with a boundary line between the first metal layer and the first polymer layer of the first seal edge at a first intersection point, the third straight line intersecting with a boundary line between the second metal layer and the second polymer layer of the first seal edge at a second intersection point, and a distance between the first intersection point and the second intersection point is defined as L. ３ , the distance between the corner point and the boundary line between the first region and the second region is L ４ Then, 0.1≦L ３ / L ４ 9. The electrochemical device of claim 8, wherein the ρ is ≦0.

6.

11. The electrochemical device comprises:

2. The electrochemical device of claim 1, further comprising a first adhesive bonding the second sealing edge and an outer surface of the first sidewall.

12. The electrochemical device comprises:

2. The electrochemical device according to claim 1, further comprising a second adhesive that bonds the inner surface of the first side wall and the electrode assembly.

13. The electrochemical device comprises:

2. The electrochemical device according to claim 1, further comprising a third adhesive that bonds an inner surface of at least one of the first wall or the second wall to the electrode assembly.

14. The electrode assembly has a wound structure, and includes a first electrode sheet, a second electrode sheet, and a separator provided between the first electrode sheet and the second electrode sheet; 2. The electrochemical device of claim 1, wherein the first electrode sheet comprises a first current collector and a first active material layer provided on the first current collector, the first current collector having a first surface, and an outer surface of an outermost periphery of the electrode assembly is the first surface.

15. 2. The electrochemical device according to claim 1, wherein the electrode assembly has a wound structure, the electrode assembly includes a first electrode sheet, a second electrode sheet, and a separator provided between the first electrode sheet and the second electrode sheet, and the outermost periphery of the electrode assembly is the separator.

16. 2. The electrochemical device of claim 1, wherein the main body portion further includes a first end wall and a second end wall arranged opposite each other in the first direction, the housing further includes a second portion connecting the first end wall, and the tab protrudes outside the housing from an edge of the second portion.

17. 17. The electrochemical device of claim 16, wherein in the second direction, the second portion is closer to the second wall than the first wall, and in the second direction, the first end wall includes a first end surface and a second end surface located on either side of the tab, the first end surface connecting the second portion and the first wall, and the second end surface connecting the second portion and the second wall.

18. The electrochemical device comprises:

18. The electrochemical device of claim 17, further comprising a fourth adhesive that bonds the first end surface and the edge of the second portion.

19. 2. The electrochemical device of claim 1, wherein the first polymer layer comprises a first polymer material and the second polymer layer comprises a second polymer material, the first polymer material and the second polymer material being each independently at least one selected from the group consisting of polypropylene, propylene copolymers, polyethylene, and polymethyl methacrylate.

20. An electronic device comprising the electrochemical device according to any one of claims 1 to 19.

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