Electrochemical device and electronic apparatus

Abstract

The invention relates to the technical field of batteries, and discloses an electrochemical device and electronic equipment, a packaging bag of the electrochemical device comprises a main body part and a top sealing part which are connected, a battery cell assembly is located in the main body part, and a sealing area of the top sealing part is provided with an edge point Q2 which is close to the edge of the battery cell assembly and located on a first wall; the top sealing part comprises a first wall extending in the first direction, a second wall of the main body part is connected with the first wall and a third wall, and a connecting point Q3 is formed at the connecting position of the second wall and the third wall; a straight line K1 is formed by the edge point Q2 and the connection point Q3; the included angle R between the first wall and the straight line K1 is larger than or equal to 80 degrees and smaller than or equal to 110 degrees. And / or, along the first direction, the distance h between the edge point Q2 and the connection point Q3 is greater than or equal to 0mm and less than or equal to 1mm. The included angle R and the distance h are controlled within the range, so that the first wall and the second wall can be vertically connected as far as possible, the space of the containing cavity is reduced, and the top sealing part is easier to be burst open in the thickness direction to achieve pressure relief during thermal runaway.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of battery technology, and in particular to an electrochemical device and an electronic device. Background Art

[0002] Soft-pack lithium-ion batteries are widely used in electronic devices due to their small size, light weight, and high power density. While pursuing the ultimate performance, the safety and reliability of soft-pack lithium-ion batteries are also particularly important. For example, in the event of a violent impact, high temperature environment, or internal battery abnormalities, thermal runaway of lithium-ion batteries may occur. Therefore, how to safely and reliably solve the thermal runaway problem of soft-pack lithium-ion batteries is an important research direction in the field of electrochemical device technology. Summary of the invention

[0003] The embodiments of the present application provide an electrochemical device and an electronic device, which can safely and effectively solve the problem of thermal runaway of the electrochemical device and improve safety performance.

[0004] In order to solve the above technical problems, a technical solution adopted in the embodiment of the present application is: to provide an electrochemical device, including a packaging bag, a battery cell assembly and a tab assembly. The packaging bag includes a main body and a top seal connected in a first direction, the main body is provided with a receiving cavity; the battery cell assembly and the tab assembly, the battery cell assembly is arranged in the receiving cavity, the tab assembly is electrically connected to the battery cell assembly, and the tab assembly is connected to the top seal; the top seal is provided with a sealing area, along the direction of the top seal toward the main body, the sealing area has an edge point located on the first wall close to the battery cell assembly; the top seal includes a first wall extending along the first direction, the main body includes a second wall and a third wall connected, the second wall is connected to the first wall and the third wall respectively, the third wall extends along the first direction, and a connection point is formed at the connection between the second wall and the third wall; a straight line is formed through the edge point and the connection point; the angle R between the first wall and the straight line satisfies: 80°≤R≤110°; and / or, along the first direction, the distance h between the edge point and the connection point satisfies: 0mm≤h≤1mm.

[0005] The electrochemical device of the embodiment of the present application shapes the first wall and the second wall of the packaging bag so that the first wall and the second wall are connected as vertically as possible, and the distance h in the first direction between the edge point of the sealing area located at the first wall and the connection point formed at the connection between the second wall and the third wall is controlled within the above-mentioned range, so that the variable space of the receiving chamber can be reduced after the sealing of the electrochemical device is completed, so that when the electrochemical device thermally runs away, the gas inside the receiving chamber has a greater pressure, the top seal portion is subjected to greater force in its thickness direction, and the top seal portion is more easily opened to achieve pressure relief.

[0006] In some embodiments, the angle R satisfies: 85°≤R≤100°; and / or the distance h satisfies: 0.2mm≤h≤0.5mm. The closer the angle R between the first wall and the second wall is to 90°, the smaller the spatial change of the receiving cavity is, and the easier it is for the top seal to be opened in the event of thermal runaway.

[0007] In some embodiments, the sealing area includes a first sealing area and a second sealing area, and the second sealing area is located between the first sealing area and the main body. Along the first direction X, that is, along the direction of the top seal portion toward the main body, the first sealing area and the second sealing area are arranged adjacent to each other or spaced apart, and the second sealing area has an edge close to the battery cell assembly and located at an edge point of the first wall. Under normal use conditions of the electrochemical device, the second sealing area can increase the binding force of the top seal portion in its thickness direction and improve its safety performance; when the electrochemical device has thermal runaway, the gas in the receiving cavity expands, the gas pressure increases, and the force point of the top seal portion is located in the second sealing area. Furthermore, the peak force of the top seal portion is located at the edge point of the second sealing area. As the temperature of thermal runaway rises, the sealing effect of the second sealing area decreases, so that the gas can break through the second sealing area and the first sealing area for pressure relief.

[0008] In some embodiments, along the thickness direction of the top seal portion, the top seal portion includes a first layer, a second layer and an adhesive layer located between the first layer and the second layer, and the adhesive layer includes a first part and a second part, the first part is located in the first sealing area, and the second part is located in the second sealing area; along the thickness direction of the top seal portion, the thickness H1 of the first part and the thickness H2 of the second part satisfy: 0.8≤H1 / H2≤1.2. In the embodiment of the present application, the adhesive layer of the second sealing area is pressurized and hot-stamped by an auxiliary top block or an auxiliary packaging ironing head to reduce the thickness of the overflow glue ball, so that the thickness of the adhesive layer is relatively uniform, thereby making the angle between the first wall of the top seal portion and the second wall of the main body closer to a right angle.

[0009] In some embodiments, the edge of the second sealing area close to the battery cell assembly is located at the edge point of the first wall, and the packaging tension F1 at room temperature of 22°C to 27°C ranges from 3N / mm to 10N / mm, and the packaging tension F2 at high temperature of 125°C to 135°C ranges from 0.01N / mm to 0.3N / mm. Through the above arrangement, the second sealing area has a good adhesive binding force at room temperature, so that the top seal has a good packaging effect, and when thermal runaway occurs, the adhesive binding force of the second sealing area becomes weak, which is conducive to the gas inside the receiving cavity breaking through the second sealing area to achieve rapid pressure relief.

[0010] In some embodiments, the tab assembly includes a tab, an insulating member and a sealing member, the tab is electrically connected to the cell assembly, the insulating member covers the connection area between the tab and the cell assembly, and the sealing member is disposed between the tab and the top seal. The insulating member covers the connection area between the tab and the cell assembly to cover the burrs on the connection area, thereby reducing the probability that the burrs pierce the cell assembly and cause the cell assembly to short-circuit. The sealing member is disposed between the tab and the top seal, and the sealing member wraps a portion of the tab to improve the sealing of the tab at the top seal.

[0011] In some embodiments, the insulating member and the adhesive layer are spaced apart from each other in the direction from the main body toward the top seal portion. This can reduce the influence of the heat during the pressurization and hot stamping of the adhesive layer on the shape of the insulating member and reduce the risk of deformation and shrinkage of the insulating member; in addition, the material selection of the adhesive layer and the material selection of the insulating member do not affect each other, which is conducive to expanding the material selection range of the two.

[0012] In some embodiments, the insulating member and the adhesive layer are integrated and connected in a direction from the main body toward the top seal. The structure in which the insulating member and the adhesive layer are integrated and connected can reduce the requirements for packaging accuracy and improve production efficiency. On the other hand, after packaging, the adhesive layer exerts a tensile force on the insulating member, reducing the risk of internal short circuit of the battery cell assembly caused by shrinkage of the insulating member. At the same time, it can also reduce the shaking amplitude of the battery cell assembly in the receiving cavity and improve the stability of the electrochemical device.

[0013] In some embodiments, the melting point M1 of the insulating member satisfies: 150°C ≤ M1 ≤ 270°C, and the melting point M2 of the adhesive layer satisfies: 50°C ≤ M2 ≤ 400°C. By setting the melting point of the insulating member and the melting point of the adhesive layer within the above range, on the one hand, the insulating member and the adhesive layer can be fused with each other to form an integrated structure during the hot stamping process, and on the other hand, after the packaging is completed, the insulating member and the adhesive layer have a certain high temperature resistance ability to ensure the stability of the electrochemical device under normal working conditions. In some embodiments, the melting point M1 of the insulating member satisfies: 150°C ≤ M1 ≤ 220°C, and the melting point M2 of the adhesive layer satisfies: 50°C ≤ M2 ≤ 160°C.

[0014] In some embodiments, the packaging bag further includes a side seal portion, which is connected to the main body; the side seal portion is provided with a third seal area and a fourth seal area, and the fourth seal area is located between the third seal area and the main body. By adding the fourth seal area between the third seal area and the main body, the seal area of ​​the side seal portion can be further increased, so that the seal area on the side seal portion is closer to the main body, thereby reducing the variable space of the receiving cavity, which is conducive to increasing the air pressure inside the receiving cavity during thermal runaway, and making it easier to break open the top seal portion to release pressure.

[0015] In some embodiments, along the direction from the main body toward the top seal portion, the length of the first sealing area ranges from 1 mm to 2.5 mm; and / or, along the direction from the main body toward the top seal portion, the length of the second sealing area ranges from 0.01 mm to 0.5 mm.

[0016] In order to solve the above technical problems, another technical solution adopted in the embodiment of the present application is: to provide an electronic device including an electrochemical device.

[0017] The beneficial effects of the embodiment of the present application are as follows: the electrochemical device of the embodiment of the present application includes a packaging bag, a battery cell assembly and a tab assembly. The packaging bag includes a main body and a top seal connected in a first direction, the main body is provided with a receiving cavity; a battery cell assembly and a tab assembly, the battery cell assembly is arranged in the receiving cavity, the tab assembly is electrically connected to the battery cell assembly, and the tab assembly is connected to the top seal; the top seal is provided with a sealing area, and along the direction of the top seal toward the main body, the sealing area has an edge point Q2 of the first wall close to the edge of the battery cell assembly; the top seal includes a first wall extending along the first direction, the main body includes a second wall and a third wall connected, the second wall is connected to the first wall and the third wall respectively, the third wall extends along the first direction, and a connection point is formed at the connection between the second wall and the third wall; a straight line is formed through the edge point and the connection point; the angle R between the first wall and the straight line satisfies: 80°≤R≤110°; and / or, along the first direction, the distance h between the edge point and the connection point satisfies: 0mm≤h≤1mm.

[0018] The electrochemical device of the embodiment of the present application shapes the first wall and the second wall of the packaging bag so that the first wall and the second wall are connected as vertically as possible, and the distance h in the first direction between the edge point of the sealing area and the connection point formed by the connection between the second wall and the third wall is controlled within the above-mentioned range, so that the variable space of the receiving chamber can be reduced after the sealing of the electrochemical device is completed, so that when the electrochemical device thermally runs away, the gas inside the receiving chamber has a greater pressure, the top seal portion is subjected to greater force in its thickness direction, and the top seal portion is more easily opened to achieve pressure relief. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application, the following is a brief introduction to the drawings required for describing the specific embodiments. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0020] Figure 1 It is a partial cross-sectional view of a lithium-ion battery in the prior art.

[0021] Figure 2 is a cross-sectional view of an electrochemical device according to an embodiment of the present application;

[0022] Figure 3 The electrochemical device of the present application embodiment is Figure 2 Partial cross-sectional view of AA;

[0023] Figure 4 The electrochemical device of the present application embodiment is Figure 2 A partial cross-sectional view of the middle BB;

[0024] Figure 5 Another embodiment of the present invention is an electrochemical device Figure 2 Partial cross-sectional view of BB.

[0025] The reference numerals in the specific implementation manner are as follows:

[0026] 100. Electrochemical device; 10. Packaging bag; 11. Main body; 111. Receiving cavity; 112. Second wall; 113. Third wall; 12. Top seal; 121. First sealing area; 122. Second sealing area; 123. First wall; 124. First layer; 125. Second layer; 126. Adhesive layer; 1261. First part; 1262. Second part; 127. Glue overflow; 13. Side seal; 131. Third sealing area; 132. Fourth sealing area; 20. Cell assembly; 21. Pole piece; 30. Tab assembly; 31. Tab; 32. Insulator; 33. Sealing member; 200. Packaging iron; 300. Auxiliary packaging iron (auxiliary top block). DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on another element or there can be one or more centered elements therebetween. When an element is described as "connected" to another element, it can be directly connected to another element or there can be one or more centered elements therebetween. The orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "vertical", "horizontal", etc. used in this specification is based on the orientation or positional relationship shown in the accompanying drawings, only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0028] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0029] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0030] See also Figure 1 , Figure 1 A simplified cross-sectional view of a soft-pack lithium-ion battery in the prior art is shown. The soft-pack lithium-ion battery includes a packaging bag 10 and a battery cell assembly 20 located inside the packaging bag 10. The packaging bag 10 is formed by punching an aluminum-plastic film to form a receiving cavity 111. After the battery cell assembly 20 is placed in the receiving cavity 111, the aluminum-plastic film is folded and hot-stamped to encapsulate it. In this way, the packaging bag 10 of the soft-pack lithium-ion battery has a main body 11 and a top seal 12. When the battery cell assembly 20 has thermal runaway, a large amount of gas and a large amount of heat will be generated in a short time, and the packaging bag 10 will bulge. If the gas in the packaging bag 10 cannot be discharged in time, the soft-pack lithium-ion battery will eventually explode and catch fire. In order to discharge the gas in the packaging bag 10 in time, the existing soft-pack lithium-ion battery usually uses the top seal 12 as a pressure relief part, and the expanded gas can be flushed out from the top seal 12 to overflow for pressure relief, thereby reducing the risk of explosion of the soft-pack lithium-ion battery.

[0031] However, Figure 1As shown, the inventor of the present application found that during the packaging process of the top sealing portion 12 of the lithium-ion battery, due to the high temperature of the packaging iron 200, which usually reaches 200°C-250°C, in order to reduce the influence of the heat radiated by the packaging iron 200 on the battery cell assembly 20, a certain distance is set between the packaging iron 200 and the battery cell assembly 20. As a result, after the packaging is completed, the first wall 123 on the top sealing portion 12 and the second wall 112 of the main body 11 have a large inclination. Specifically, the sealing area in the top sealing portion 12 is close to the battery cell assembly. The edge Q1 of 20 and the connection point Q3 of the main body 11 close to the top seal part 12 form a straight line K1. The angle R between the first wall 123 of the top seal part 12 and the straight line K1 is a relatively large obtuse angle. For example, the angle R exceeds 135 degrees, which results in that when the battery cell assembly 20 has thermal runaway, the variable space of the accommodating cavity 111 in the main body 11 is relatively large. According to the ideal gas state equation PV=NRT (wherein P is the pressure of the gas, in Pa; V is the volume of the gas, in m3; N is the number of moles of the gas, in mol; R is the ideal gas constant, whose value is 8.314J / (mol·K); T is the absolute temperature of the gas, in K), it can be seen that when the temperature T increases, assuming that R remains unchanged, in the same electrochemical device 100 system, it is believed that the number of moles of gas N generated at the same temperature is constant, and the change in the volume V of the gas directly affects the pressure P of the gas. Specifically, the greater the change in the volume V of the gas, the smaller the change in the pressure P of the gas. When the gas pressure P during thermal runaway is insufficient to break open the top seal 12 for pressure relief, the lithium-ion battery will eventually swell or even explode.

[0032] Based on the above problems, in the electrochemical device 100 of the embodiment of the present application, the packaging process of the packaging bag 10 is adjusted, so that the structure between the main body 11 and the top seal part 12 after the packaging is completed changes, the angle R between the first wall 123 and the straight line K1 is as close to a right angle as possible, and the distance h between the edge point Q2 of the sealing area on the top seal part 12 and the connection point Q3 in the main body 11 close to the top seal part 12 is controlled within a certain range. In this way, on the one hand, the variable space of the receiving cavity 111 in the main body 11 can be reduced, so that when thermal runaway occurs, the gas inside the receiving cavity 111 has a larger pressure P, and then the top seal part 12 can be opened for pressure relief; on the other hand, Figure 1 and Figure 3 As shown, the stress point Q1 on the top seal portion 12 is close to the battery cell assembly 20 to form a stress point Q3, so that during the thermal runaway process, the top seal portion 12 is more easily opened in the thickness direction Y to achieve safe pressure relief.

[0033] See also Figure 2 and Figure 3The electrochemical device 100 of the embodiment of the present application includes a packaging bag 10, a battery cell assembly 20 and a tab assembly 30. The packaging bag 10 includes a main body 11 and a top seal 12 connected in a first direction X, and the main body 11 is provided with a receiving cavity 111. The first direction X is the direction in which the tab assembly 30 extends out of the packaging bag 10. The battery cell assembly 20 is disposed in the receiving cavity 111, the tab assembly 30 is electrically connected to the battery cell assembly 20, a portion of the tab assembly 30 is connected to the top seal 12, and a portion of the tab assembly 30 extends out of the receiving cavity 111.

[0034] in Figure 3 The viewing angle is the viewing angle of the electrochemical device 100 after being cut along the thickness direction Y. The top seal portion 12 is provided with a sealing area. Along the direction of the top seal portion 12 toward the main body portion 11, the sealing area has an edge point Q2 close to the edge of the battery cell assembly and located at the first wall; the top seal portion 12 includes a first wall 123 extending along the first direction X. The main body portion 11 includes a second wall 112 and a third wall 113 connected to each other. The second wall 112 is connected to the first wall 123 and the third wall 113 respectively. The third wall 113 extends along the first direction X, and a connection point Q3 is formed at the connection between the second wall 112 and the third wall 113. A straight line K1 is formed through the edge point Q2 and the connection point Q3; the angle R between the first wall 123 and the straight line K1 satisfies: 80°≤R≤110°; and / or, along the first direction X, the distance h between the edge point Q2 and the connection point Q3 satisfies: 0mm≤h≤1mm.

[0035] Compared with the structure of the prior art that only one packaging iron head 200 is used to package the top seal part 12, when preparing the electrochemical device 100 of the embodiment of the present application, an auxiliary top block 300 is added to the side of the original packaging head 200 close to the battery cell assembly 20, and the auxiliary top block 300 is arranged close to the main body 11 of the packaging bag 10. During the packaging process, the auxiliary top block 300 abuts against the first wall 123 and the second wall 112 respectively to shape the first wall 123 and the second wall 112 so that the first wall 123 and the second wall 112 are connected as vertically as possible. In addition, by controlling the distance between the edge point Q2 and the connection point Q3 in the first direction X within the range of 0 mm to 1 mm, after the sealing is completed, on the one hand, the variable space of the receiving chamber 111 can be reduced, so that when the electrochemical device is thermally runaway, the gas inside the receiving chamber 111 has a greater pressure; on the other hand, when the original packaging head 200 is used to package the top seal part 12, an overflow glue mass 127 (such as Figure 1As shown in the figure, the overflow glue ball 127 partially expands the top seal part 12, causing the space of the accommodating cavity 111 to become larger, and at this time, the force point Q1 of the top seal part 12 is located between the sealing area and the overflow glue ball 127, and under the abutment and compression of the auxiliary top block 300, the overflow glue ball 127 will be squeezed to bond the top seal parts on the upper and lower sides, thereby reducing the variable space of the accommodating cavity 111, and the overflow glue ball 127 is squeezed and spread along the first direction X, so that the force point Q1 on the top seal part 12 is close to the battery cell assembly 20 to form a force point Q2. During the thermal runaway process, the force on the force point Q2 in the thickness direction Y of the top seal part 12 is greater, and the top seal part 12 is more easily opened to achieve pressure relief.

[0036] In some embodiments, the angle R between the first wall 123 and the straight line K1 satisfies: 85°≤R≤100°. According to the aforementioned thermal runaway process analysis, the closer the angle between the first wall 123 and the straight line K1 is to 90 degrees, the closer the first wall 123 and the second wall 112 are to vertical connection, the smaller the spatial change of the receiving cavity 111, and the easier it is for the top seal 12 to be opened. In some embodiments, R can be 85°, 86°, 87°, 88°, 89°, 90°, 91°, 92°, 93°, 94°, 95°, 96°, 97°, 98°, 99°, 100°, etc.

[0037] In some embodiments, along the first direction X, the distance h between the edge point Q2 and the connection point Q3 satisfies: 0.2 mm ≤ h ≤ 0.5 mm. When the distance h between the edge point Q2 and the connection point Q3 is closer to 0, it means that the edge point Q2 and the connection point Q3 are more flush in the thickness direction Y, and the second wall 112 of the main body 11 is closer to extending in a direction perpendicular to the first direction X, so that the first wall 123 is vertically connected to the second wall 112.

[0038] In some embodiments, along the first direction X, the sealing area includes a first sealing area 121 and a second sealing area 122, and the second sealing area 122 is located between the first sealing area 121 and the main body 11. Along the direction of the top seal portion 12 toward the main body 11, the first sealing area 121 and the second sealing area 122 are adjacently arranged or spaced apart. The second sealing area 122 is located near the edge of the battery cell assembly 20 on the first wall to form the edge point Q2. Under normal use conditions of the electrochemical device 100, the second sealing area 122 can increase the binding force of the top seal portion 12 in its thickness direction Y and improve its safety performance. In addition, the addition of the second sealing area 122 helps to maintain the spatial stability of the accommodating cavity 111 and reduce the probability of the space of the top seal portion 12 being expanded at the position where the original overflow glue ball 127 is located. When the electrochemical device 100 experiences thermal runaway, the gas in the containing cavity 111 expands and the gas pressure increases, and the force point Q2 of the top seal portion 12 is located at the second sealing area 122. Furthermore, the peak force of the top seal portion 12 is located at the edge point Q2 of the second sealing area 122. As the temperature of the thermal runaway rises, the sealing effect of the second sealing area 122 decreases, so that the gas can break through the second sealing area 122 and the first sealing area 121 in the thickness direction of the top seal portion 12 to release pressure.

[0039] In the aforementioned embodiment, an auxiliary top block 300 may be added to the side of the original packaging iron 200 close to the main body 11 to achieve the shaping of the first wall 123 and the second wall 112, or an auxiliary packaging iron 300 may be added to the side of the original packaging iron 200 close to the main body 11, and the auxiliary packaging iron 300 has a heating function, so as to form a second sealing area 122 on the top sealing part 12. In order to reduce the influence of the heat radiated by the auxiliary packaging iron 300 on the battery core assembly 20 in the main body 11, the temperature of the auxiliary packaging iron 300 may be lower than the temperature of the original packaging iron 200.

[0040] In some embodiments, see Figure 3 The top seal portion 12 includes a first layer 124, a second layer 125, and an adhesive layer 126 located between the first layer 124 and the second layer 125. The adhesive layer 126 includes a first portion 1261 and a second portion 1262. The first portion 1261 is located in the first sealing area 121, and the second portion 1262 is located in the second sealing area 122. Along the thickness direction Y of the top seal portion 12, the thickness H1 of the first portion 1261 and the thickness H2 of the second portion 1262 satisfy: 0.8≤H1 / H2≤1.2.

[0041] In the prior art, when the first sealing area 121 is pressurized and hot-stamped by the original packaging ironing head 200, part of the adhesive layer 126 overflows at the corresponding position of the second sealing area 122 of the present application to form an overflow glue ball 127 (such as Figure 1 and Figure 3As shown, since the overflow glue ball 127 is not further pressurized, the thickness of the overflow glue ball 127 in the thickness direction Y of the top seal portion 12 is much greater than the thickness of the adhesive layer 126 in the first sealing area 121, resulting in an increase in the distance between the first layer 124 and the second layer 125 in the unsealed area close to the main body 11, that is, the second sealing area 122 in the present application, which in turn causes the angle between the first wall 123 of the top seal portion 12 and the second wall 112 of the main body 11 to be difficult to approach a right angle, and the requirement for rapid pressure relief during thermal runaway cannot be met.

[0042] In the embodiment of the present application, the auxiliary top block 300 or the auxiliary packaging ironing head 300 is added to pressurize and heat-seal the adhesive layer 126 of the second sealing area 122, thereby reducing the thickness of the overflow glue mass 127, so that the thickness of the adhesive layer 126 is relatively uniform, and thus the angle between the first wall 123 of the top sealing portion 12 and the second wall 112 of the main body 11 is close to a right angle, so that the electrochemical device 100 is within the normal use temperature range, and the second sealing area 122 is at the top of the top sealing portion 12. The packaging tension in the thickness direction Y increases, thereby improving the structural strength and sealing performance of the top seal 12; when the electrochemical device 100 is in thermal runaway, the stress of the second sealing area 122 in the thickness direction Y of the top seal 12 increases, and under high temperature conditions (125°C to 135°C), the adhesive layer 126 melts, and the high-temperature and high-pressure gas in the receiving cavity 111 separates the first layer 124 and the second layer 125 in the thickness direction Y of the top seal 12, and rushes out of the receiving cavity 111 to achieve pressure relief.

[0043] In a further example, along the thickness direction Y of the top seal portion 12 , the thickness H1 of the first portion 1261 and the thickness H2 of the second portion 1262 of the adhesive layer 126 are equal or almost equal, that is, the ratio between the two is 1 or close to 1.

[0044] In some embodiments, the edge of the second sealing area 122 close to the battery cell assembly 20 is located at the edge point Q2 of the first wall, and the packaging tension F1 at room temperature 22°C to 27°C ranges from 3N / mm to 10N / mm, which improves the structural strength and sealing performance of the top seal 12; the packaging tension F2 at high temperature 125°C to 135°C ranges from 0.01N / mm to 0.3N / mm. When thermal runaway occurs, the adhesive layer 126 melts, making it easy for the gas to separate the first layer 124 and the second layer 125 in the thickness direction Y of the top seal 12, and rush out of the receiving cavity 111 to achieve pressure relief.

[0045] In some embodiments, see Figure 2, along the direction of the main body 11 toward the top seal 12, the length L1 of the first seal area 121 is 1mm to 2.5mm; and / or, along the direction of the main body 11 toward the top seal 12, the length L2 of the second seal area 122 is 0.01mm to 0.5mm. In the embodiment of the present application, the packaging and sealing function of the top seal 12 is mainly ensured by the first seal area 121, and the main function of setting the second seal area 122 is to shape the first wall 123 and the second wall 112 and to move the stress point Q2 of the top seal 12 closer to the battery cell assembly 20, while reducing the space of the accommodating cavity 111 and increasing the stress at the stress point Q2 during thermal runaway, so that the gas can break through the first seal area 121 and the second seal area 122 for pressure relief. Therefore, the seal length L1 of the first seal area 121 needs to be longer than the seal length L2 of the second seal area 122, and the seal length L2 of the second seal area 122 should not be too long.

[0046] In some embodiments, see Figure 2 The tab assembly 30 includes a tab 31, an insulating member 32 and a sealing member 33. One end of the tab 31 is electrically connected to the cell assembly 20, and the other end of the tab 31 extends out of the receiving cavity 111 from the top seal portion 12 of the packaging bag 10. The insulating member 32 covers the connection area between the tab 31 and the cell assembly 20 to cover the burrs on the connection area, thereby reducing the probability that the burrs pierce the cell assembly 20 and cause the cell assembly 20 to short-circuit. The sealing member 33 is disposed between the tab 31 and the top seal portion 12, and the sealing member 33 wraps a portion of the tab 31 to improve the sealing of the tab 31 at the top seal portion 12.

[0047] In some embodiments, the way in which the tab 31 is electrically connected to the cell assembly 20 includes but is not limited to: the tab 31 is welded to the pole piece 21 of the cell assembly 20 , or the protruding tab 31 is formed by cutting the pole piece 21 .

[0048] In some embodiments, see Figure 4 , along the direction of the main body 11 toward the top seal 12, the insulating member 32 and the adhesive layer 126 are spaced apart. On the premise that the insulating member 32 can cover the connection area between the tab 31 and the battery cell assembly 20, the structure in which the insulating member 32 and the adhesive layer 126 are spaced apart can firstly reduce the length of the insulating member 32 and reduce the production cost; secondly, it can reduce the influence of the heat during the pressurization and hot stamping process of the adhesive layer 126 on the shape of the insulating member 32 and reduce the risk of deformation and shrinkage of the insulating member 32; thirdly, it can make the material selection of the adhesive layer 126 and the material selection of the insulating member 32 independent of each other, which is conducive to increasing the respective material selection ranges of the two.

[0049] In some embodiments, see Figure 5, along the direction of the main body 11 toward the top seal portion 12, the insulating member 32 and the adhesive layer 126 are fused and connected as one piece. In the production process of the electrochemical device 100, the insulating member 32 is first set in the connection area between the pole ear 31 and the battery cell assembly 20, and then the battery cell assembly 20 is placed in the receiving cavity 111, and then the top seal portion 12 of the packaging bag 10 is hot-stamped. It is desirable to keep a spacing between the insulating member 32 and the adhesive layer 126, especially in a small-sized electrochemical device 100, and the packaging precision is required to be high. Therefore, the embodiment of the present application appropriately extends the length of the insulating member 32 so that the insulating member 32 contacts or partially overlaps the adhesive layer 126. During the process of pressurized hot stamping packaging, the insulating member 32 and the adhesive layer 126 are fused and connected as one piece. In this embodiment, the material selection of the insulating member 32 is related to the material selection of the adhesive layer 126, that is, the melting points of the two are close or the same, so that the two can be melted into one piece. By integrating the insulating part 32 and the adhesive layer 126 into an integrated structure, on the one hand, the requirements for packaging accuracy are reduced and production efficiency is improved; on the other hand, after the packaging is completed, the adhesive layer 126 exerts a tensile force on the insulating part 32, reducing the risk of internal short circuit of the battery cell assembly 20 caused by shrinkage of the insulating part 32. At the same time, it can also reduce the shaking amplitude of the battery cell assembly 20 in the receiving cavity 111, thereby improving the internal stability of the electrochemical device 100.

[0050] In some embodiments, the melting point M1 of the insulating member 32 satisfies: 150°C ≤ M1 ≤ 270°C, and the melting point M2 of the adhesive layer 126 satisfies: 50°C ≤ M2 ≤ 400°C. By setting the melting point of the insulating member 32 and the melting point of the adhesive layer 126 within the above range, on the one hand, the insulating member 32 and the adhesive layer 126 can be fused with each other to form an integrated structure during the hot stamping process, and on the other hand, after the packaging is completed, the insulating member 32 and the adhesive layer 126 both have a certain high temperature resistance, ensuring the stability of the electrochemical device 100 under normal working conditions. In a further embodiment, the melting point M1 of the insulating member 32 satisfies: 150°C ≤ M1 ≤ 220°C, and the melting point M2 of the adhesive layer 126 satisfies: 50°C ≤ M2 ≤ 160°C.

[0051] In some embodiments, see Figure 2 The packaging bag 10 further includes a side seal portion 13, which is connected to the main body 11. The side seal portion 13 is provided with a third seal area 131 and a fourth seal area 132, and the fourth seal area 132 is located between the third seal area 131 and the main body 11. By adding the fourth seal area 132 between the third seal area 131 and the main body 11, the seal area of ​​the side seal portion 13 can be further increased, so that the seal area on the side seal portion 13 is close to the main body 11, thereby reducing the variable space of the receiving cavity 111, which is conducive to increasing the air pressure inside the receiving cavity during thermal runaway, and it is easier to break the top seal to release pressure.

[0052] According to the ideal gas state equation PV=NRT, assuming that the number of moles of gas N and the ideal gas constant R remain unchanged, when thermal runaway occurs inside the electrochemical device 100, the temperature T rises. At this time, if the space V of the receiving chamber 111 remains unchanged or changes slightly, the more the gas pressure P increases, the more it is conducive to the high-temperature and high-pressure gas to break through the top seal 12 of the packaging bag 10 for pressure relief. It is understandable that the fourth sealing area 132 can be added to the side seal 13 on one side of the packaging bag 10, or the fourth sealing area 132 can be added to the side seals 13 on both sides of the packaging bag 10, so as to further reduce the variable space of the receiving chamber 111.

[0053] The present application further provides an electronic device embodiment, the electronic device includes an electrochemical device 100. The structure and function of the electrochemical device 100 may refer to any of the above embodiments, which will not be described in detail here.

[0054] The electrochemical device 100 of the embodiment of the present application includes a packaging bag 10, a battery cell assembly 20 and a tab assembly 30. The packaging bag 10 includes a main body 11 and a top seal 12 connected to each other, and the main body 11 is provided with a receiving cavity 111. The battery cell assembly 20 is disposed in the receiving cavity 111, the tab assembly 30 is electrically connected to the battery cell assembly 20, and the tab assembly 30 is connected to the top seal 12.

[0055] The top seal portion 12 is provided with a sealing area, and along the direction of the top seal portion 12 toward the main body portion 11, the sealing area has an edge point Q2 of the first wall close to the edge of the battery cell assembly; the top seal portion 12 includes a first wall 123 extending along the first direction X. The main body portion 11 includes a second wall 112 and a third wall 113 connected to each other, the second wall 112 is connected to the first wall 123 and the third wall 113 respectively, the third wall 113 extends along the first direction X, and a connection point Q3 is formed at the connection between the second wall 112 and the third wall 113. A straight line K1 is formed through the edge point Q2 and the connection point Q3; the angle R between the first wall 123 and the straight line K1 satisfies: 80°≤R≤110°; and / or, along the first direction X, the distance h between the edge point Q2 and the connection point Q3 satisfies: 0mm≤h≤1mm.

[0056] The electrochemical device 100 of the present application controls the angle R between the first wall 123 and the straight line K1 to satisfy: 80°≤R≤110°; and / or the distance h between the edge point Q2 and the connection point Q3 along the first direction X to satisfy: 0mm≤h≤1mm, which is conducive to the first wall 123 and the second wall 112 being connected as vertically as possible, reducing the variable space of the receiving cavity 111, and making the force point Q2 on the top seal 12 close to the corner of the first wall 123 and the second wall 112. Under normal use conditions of the electrochemical device 100, the restraining force of the top seal 12 in its thickness direction Y can be increased to improve its safety performance. During the thermal runaway process, the force point Q2 is subjected to greater force in the thickness direction Y of the top seal 12, and the top seal 12 is more easily opened to achieve pressure relief.

[0057] The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. An electrochemical device, characterized in that: include: The packaging bag comprises a main body and a top seal part connected in a first direction, wherein the main body is provided with a receiving cavity; A battery cell assembly and a tab assembly, wherein the battery cell assembly is disposed in the receiving cavity, the tab assembly is electrically connected to the battery cell assembly, and the tab assembly is connected to the top sealing portion; The top seal portion is provided with a sealing area and a first wall extending along the first direction, and along the direction from the top seal portion toward the main body portion, the sealing area has an edge close to the battery core assembly and located at an edge point of the first wall; The main body comprises a second wall and a third wall connected to each other, the second wall is connected to the first wall and the third wall respectively, the third wall extends along the first direction, a connection point is formed at the connection between the second wall and the third wall; a straight line is formed through the edge point and the connection point; The angle R between the first wall and the straight line satisfies: 80°≤R≤110°; and / or, Along the first direction, a distance h between the edge point and the connection point satisfies: 0 mm ≤ h ≤ 1 mm.

2. The electrochemical device according to claim 1, characterized in that The angle R satisfies: 85°≤R≤100°; and / or, the distance h satisfies: 0.2mm≤h≤0.5mm.

3. The electrochemical device according to claim 1, characterized in that The sealing area includes a first sealing area and a second sealing area, the second sealing area is located between the first sealing area and the main body, along the first direction, the first sealing area and the second sealing area are adjacent to or spaced apart, and the second sealing area has an edge point located on the first wall close to the edge of the battery cell assembly.

4. The electrochemical device according to claim 3, characterized in that Along the thickness direction of the top seal portion, the top seal portion includes a first layer, a second layer and an adhesive layer located between the first layer and the second layer, the adhesive layer includes a first part and a second part, the first part is located in the first sealing area, and the second part is located in the second sealing area; Along the thickness direction of the top seal portion, a thickness H1 of the first portion and a thickness H2 of the second portion satisfy: 0.8≤H1 / H2≤1.

2.

5. The electrochemical device according to claim 4, characterized in that At the edge point of the second sealing area close to the battery cell assembly, the packaging tension F1 ranges from 3N / mm to 10N / mm at room temperature of 22°C to 27°C, and the packaging tension F2 ranges from 0.01N / mm to 0.3N / mm at high temperature of 125°C to 135°C.

6. The electrochemical device according to claim 1, characterized in that The tab assembly includes a tab, an insulating member and a sealing member. The tab is electrically connected to the cell assembly. The insulating member covers the connection area between the tab and the cell assembly. The sealing member is disposed between the tab and the top seal.

7. The electrochemical device according to claim 6, characterized in that Along the direction from the main body to the top seal portion, the insulating member and the adhesive layer are spaced apart; or, Along the direction from the main body to the top sealing portion, the insulating member and the adhesive layer are integrated and connected.

8. The electrochemical device according to claim 7, characterized in that The melting point M1 of the insulating member satisfies: 150°C≤M1≤270°C, and the melting point M2 of the adhesive layer satisfies: 50°C≤M2≤400°C.

9. The electrochemical device according to claim 8, characterized in that The melting point M1 of the insulating member satisfies: 150°C≤M1≤220°C, and the melting point M2 of the adhesive layer satisfies: 50°C≤M2≤160°C.

10. The electrochemical device according to claim 1, characterized in that The packaging bag further comprises a side sealing portion, wherein the side sealing portion is connected to the main body portion; The side sealing portion is provided with a third sealing area and a fourth sealing area, and the fourth sealing area is located between the third sealing area and the main body.

11. The electrochemical device according to claim 1, characterized in that Along the direction from the main body to the top seal portion, the length of the first sealing area ranges from 1 mm to 2.5 mm; and / or, Along the direction from the main body to the top seal portion, the length of the second sealing area ranges from 0.01 mm to 0.5 mm.

12. An electronic device, characterized in that: Comprising the electrochemical device according to any one of claims 1-11.

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