Electrochemical device and electronic equipment

Abstract

The present application provides an electrochemical device and an electronic device, wherein the electrochemical device includes a shell, at least one partition and at least two electrode assemblies. The shell includes a first shell and a second shell. The partition is arranged between the first shell and the second shell. The electrochemical device is provided with at least two cavities between the first shell and the second shell. The electrode assembly includes a pole piece assembly and at least two pole ears connected to the pole piece assembly, and the pole piece assembly is accommodated in the cavity. Among them, the electrochemical device includes a first sealing portion, and the first sealing portion includes a first sealing edge; along the thickness direction of the first sealing portion, the maximum distance between each pole ear located in the first sealing portion at the first sealing edge is d, and the thickness of the electrochemical device is D, satisfying d≤0.4D. In this way, the packaging reliability of the electrochemical device can be improved.

Description

Technical Field

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

[0002] At present, batteries are widely used in electronic products such as drones, mobile phones, tablets, and laptops. Because in some application scenarios, a single battery cell cannot achieve the desired output power; therefore, multiple battery cells are usually connected in series, in parallel, or in mixed connection, so that the multiple battery cells work together to achieve the desired power output. However, although connecting multiple battery cells in series, in parallel, or in mixed connection can increase the output power, the energy density of the entire battery pack is low. Therefore, the design of same-bag series / parallel batteries is proposed. The same-bag series / parallel batteries include a shell and a plurality of electrode assemblies arranged in the same shell. The electrode assemblies in series need to be separated by an isolator to avoid decomposition of the electrolyte under high voltage, and the electrode assemblies in parallel are separated by an isolator to avoid interference with each other. Summary of the invention

[0003] The inventors of the present application have discovered through research that when the tabs of multiple electrode assemblies in the same bag of series / parallel connected batteries extend out of the shell from the sealing edge on the same side of the shell, the packaging reliability of the sealing edge will be insufficient, posing a safety risk.

[0004] In view of the above technical problems, the present application provides an electrochemical device and an electronic device to improve the packaging reliability of batteries connected in series or in parallel in the same bag.

[0005] In order to solve the above technical problems, the first aspect of the present application is to provide an electrochemical device, including a shell, at least one partition and at least two electrode assemblies. The shell includes a first shell and a second shell. The partition is arranged between the first shell and the second shell, so that the electrochemical device has at least two cavities between the first shell and the second shell. The electrode assembly includes a pole piece assembly and at least two pole ears connected to the pole piece assembly, and the pole piece assembly is accommodated in the cavity. Among them, the electrochemical device includes a first sealing portion, and the first sealing portion includes a first sealing edge; along the thickness direction of the first sealing portion, the maximum distance between each pole ear located in the first sealing portion at the first sealing edge is d, and the thickness of the electrochemical device is D, which satisfies: d≤0.4D.

[0006] By satisfying d≤0.4D, the surface flatness of the first sealing portion can be improved, and the risk of weak sealing strength due to local undervoltage when the shell and the partition are packaged at the first sealing portion due to excessive height difference of the tab in the thickness direction of the first sealing portion can be reduced. At the same time, the side wall of the shell can provide appropriate strain for the packaging at the undervoltage portion of the first sealing portion, promote the packaging between the shell and the partition at the undervoltage portion, and thus improve the reliability of the packaging.

[0007] Optionally, the electrochemical device satisfies at least one of the following conditions: (1) d≤0.15D; (2) d≤2mm. When at least one of the two conditions is met, the flatness of the first sealing portion can be further improved, thereby improving the uniformity of the pressure at each location when the shell and the partition are packaged at the first sealing portion, thereby further improving the packaging reliability of the first sealing portion.

[0008] Optionally, at least two tabs of at least one of the electrode assemblies extend from a first side end of the shell, and at least two tabs of at least one of the electrode assemblies extend from a second side end of the shell, and the first side end is adjacent to or opposite to the second side end. In this way, it is possible to avoid that multiple tabs of multiple electrode assemblies occupy too much space on the same side of the shell, and multiple tabs distributed on different sides of the shell can also meet different connection requirements.

[0009] Optionally, at least two tabs of at least one of the electrode assemblies extend from the first side end and the second side end of the shell, respectively. Thus, the electrode assemblies with at least two tabs extending from the first side end or the second side end can be conveniently connected in series through the two tabs of the electrode assembly.

[0010] Optionally, the partition includes a first packaging layer, a second packaging layer and an intermediate layer, and the intermediate layer is located between the first packaging layer and the second packaging layer.

[0011] Optionally, the electrode assembly includes an adjacent first electrode assembly and a second electrode assembly, the partition includes a first partition located between the first electrode assembly and the second electrode assembly, the electrode ear of the first electrode assembly includes a first electrode ear, the electrode ear of the second electrode assembly includes a second electrode ear adjacent to the first electrode ear, along the length direction of the first sealing edge, the distance between the first electrode ear and the second electrode ear at the first sealing edge is L, the thickness of the first partition is T, and L / T≥15.

[0012] On the one hand, the staggered arrangement of the first pole ear and the second pole ear can reduce the difference in the sealing thickness of the first sealing portion relative to the overlapping arrangement of the first pole ear and the second pole ear, thereby improving the packaging reliability at the pole ear; on the other hand, by satisfying the above relationship, the bending degree of the partition between the pole ears can be effectively reduced, so that the stress and strain it is subjected to is smaller, and the partition at the side corners of the pole ears can better fit other components connected to it (such as a shell) during sealing, and when the pole ear is subjected to external stress pulling the partition, it is not easy to peel off, thereby further improving the packaging reliability.

[0013] Optionally, the electrochemical device satisfies at least one of the following conditions: (1) the thickness of the first electrode tab is h 1 , L / h 1≥10; (2) the thickness of the second pole ear is h 2 , L / h 2 ≥10; at this time, the bending degree of the partition between the tabs can be further reduced, so that the stress and strain it is subjected to is relatively small, and the fit of the partition with other components at the side corners of the first tab and / or the second tab is further improved, thereby further improving the packaging reliability.

[0014] Optionally, the electrochemical device satisfies at least one of the following: (3) L / (h 1 +T)≥5; (4)L / (h 2 +T)≥5; (5)h 1 ≤0.2mm; (6)h 2 ≤0.2mm. At this time, the bending degree of the partition between the tabs can be further reduced, so that the stress and strain it is subjected to is smaller, and the fit of the partition with other components at the side corners of the first tab and / or the second tab is further improved, thereby further improving the packaging reliability.

[0015] Optionally, the pole piece assembly includes at least one of a winding structure or a stacked structure.

[0016] In a second aspect of the present application, an electronic device is also provided, comprising the above-mentioned electrochemical device.

[0017] The beneficial effect of the embodiment of the present application is that the electrochemical device provided by the present application satisfies d≤0.4D by the maximum distance d between the pole ears of the first sealing part at the first sealing edge along the thickness direction of the first sealing part and the thickness D of the electrochemical device. In this way, the flatness of the position of the first sealing part can be improved, and the risk of weak sealing strength due to local undervoltage when the shell and the partition are packaged at the first sealing part due to excessive height difference of the pole ears in the thickness direction of the first sealing part can be reduced. At the same time, the side wall of the shell can provide appropriate strain for the packaging of the undervoltage part of the first sealing part, promote the packaging between the shell and the partition at the undervoltage part, and thus improve the packaging reliability of the first sealing part. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on the drawings.

[0019] Figure 1 is a schematic structural diagram of an electrochemical device in one embodiment of the present application;

[0020] Figure 2 yes Figure 1 Schematic diagram after sectioning along the straight line MM';

[0021] Figure 3 is a schematic diagram of an embodiment in which the pole piece assembly is a winding structure;

[0022] Figure 4 is a schematic diagram of another embodiment in which the pole piece assembly is a laminated structure;

[0023] Figure 5 yes Figure 1 Schematic diagram after cutting along the XY plane;

[0024] Figure 6 yes Figure 1 Front view of

[0025] Figure 7 yes Figure 6 A magnified view of part B;

[0026] Figure 8 yes Figure 7 Schematic diagram of the structure of the middle part;

[0027] Fig. 9 yes Figure 1 A schematic diagram of a partial structure of an electrochemical device in the right view;

[0028] Fig.10 It is a schematic structural diagram of an electrochemical device with multiple side tabs in another embodiment. DETAILED DESCRIPTION

[0029] 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.

[0030] 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.

[0031] 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.

[0032] like Figure 1-2 As shown, an electrochemical device 100 provided in one embodiment of the present application includes a housing 10, an electrode assembly 20, and a separator 30. The housing 10 includes a first housing 12 and a second housing 14. The housing 10 is used to limit a closed space for accommodating the electrode assembly 20. The separator 30 is located between the first housing 12 and the second housing 14. The separator 30 is used to separate the internal space of the housing 10, thereby increasing the number of independent cavities inside the housing 10.

[0033] The electrochemical device 100 may include one separator 30 or multiple separators 30. When the electrochemical device 100 includes one separator 30, one separator 30 may separate the internal space of the housing 10 into two independent cavities. When the electrochemical device 100 includes multiple separators 30, multiple separators 30 may separate the internal space of the housing 10 into multiple independent cavities. For example, when the electrochemical device 100 specifically includes two separators 30, the two separators 30 may separate the internal space of the housing 10 into three independent cavities; when the electrochemical device 100 includes three separators 30, the three separators 30 separate the internal space of the housing 10 into four independent cavities.

[0034] For ease of description, the following embodiments are described by taking the electrochemical device 100 as including a separator 30. The separator 30 divides the internal space of the housing 10 into two independent chambers, which are respectively referred to as a first chamber 101 and a second chamber 102.

[0035] The electrochemical device 100 may include two electrode assemblies 20 or may include more than three electrode assemblies 20. For ease of description, in the following embodiments, the electrochemical device 100 includes two electrode assemblies 20 for example. Figure 2As shown, the two electrode assemblies 20 are respectively a first electrode assembly 20a and a second electrode assembly 20b. When the electrochemical device 100 has a separator 30, and the separator 30 separates two independent cavities, the first electrode assembly 20a is disposed in the aforementioned first cavity 101, and the second electrode assembly 20b is disposed in the aforementioned second cavity 102. The first electrode assembly 20a, the separator 30, and the second electrode assembly 20b are distributed along a first direction Z, and the first direction Z is the same as the thickness direction of the separator 30.

[0036] In some embodiments, please combine Figure 3 The electrode assembly 20 includes a pole piece assembly 21 and a pole ear 22 connected to the pole piece assembly 21. The number of the pole ears 22 is at least two, and the polarities of at least two pole ears 22 are different. In some embodiments, the pole piece assembly 21 includes a first pole piece 211, a second pole piece 212, and an isolation film 213. The isolation film 213 is disposed between the first pole piece 211 and the second pole piece 212. The polarities of the first pole piece 211 and the second pole piece 212 are opposite. The isolation film 213 is used to reduce the risk of short circuit between the first pole piece 211 and the second pole piece 212.

[0037] In some embodiments, Figure 1 As shown, the plurality of tabs 22 of the electrode assembly 20 may all extend from the first side end of the housing 10. Fig.10 As shown, the multiple tabs 22 of the electrode assembly 20 may also extend from different side ends of the shell 10, that is, at least two tabs 22 of one electrode assembly 20 extend from the first side end of the shell 10, and at least two tabs 22 of another electrode assembly 20 extend from the second side end of the shell. In some embodiments, the first side end of the shell 10 and the second side end of the shell 10 are two opposite ends, and in other embodiments, the first side end of the shell 10 and the second side end of the shell 10 are two adjacent ends.

[0038] In some embodiments, Figure 3 As shown, the pole piece assembly 21 may be a winding structure, that is, the first pole piece 211, the second pole piece 212 and the isolation film 213 are stacked and wound. Figure 4 As shown, the pole piece assembly 21 can be a stacked structure, in which case the number of the first pole piece 211, the second pole piece 212 and the isolation membrane 213 are multiple, and the isolation membrane 213 is located between an adjacent first pole piece 211 and a second pole piece 212, and the first pole piece 211, the isolation membrane 213 and the second pole piece 212 are stacked along a direction, which is the thickness direction of the first pole piece 211, the isolation membrane 213 or the second pole piece 212.

[0039] It can be understood that the structure of the pole piece assembly of the first electrode assembly 20a and the pole piece assembly of the second electrode assembly 20b can be the same, that is, the pole piece assembly of the first electrode assembly 20a and the pole piece assembly of the second electrode assembly 20b can both be a winding structure or a laminated structure. In addition, the structure of the pole piece assembly of the first electrode assembly 20a and the pole piece assembly of the second electrode assembly 20b can also be different, that is, one of the pole piece assembly of the first electrode assembly 20a and the pole piece assembly of the second electrode assembly 20b is a winding structure, and the other can be a winding structure.

[0040] For ease of description, in this embodiment, one of the pole ears of the first electrode assembly 20a is referred to as the first pole ear 221. The first pole ear 221 can be a positive pole ear or a negative pole ear. In this embodiment, one of the pole ears of the second electrode assembly 20b is referred to as the second pole ear 222, and the second pole ear 222 can be a positive pole ear or a negative pole ear. The polarities of the first pole ear 221 and the second pole ear 222 can be the same or different. The first pole ear 221 and the second pole ear 222 can be electrically connected to each other or not.

[0041] like Figure 5 As shown, the separator 30 includes a first sealing area 31. When the electrochemical device 100 is packaged, the portion of the separator 30 located in the first sealing area 31 is sealed with other components. That is, the portion of the separator 30 in the first sealing area 31 is fixedly connected to other components (it can be hot-melt connection or bonding). When the electrochemical device 100 has only one separator 30, both side walls of the first sealing area 31 of the separator 30 are connected to the shell 10. When the electrochemical device 100 has two separators 30, one side wall of the first sealing area 31 of one separator 30 is connected to the other separator 30, and the other side wall is connected to the shell 10. When the number of separators 30 is three or more, both side walls of the first sealing area 31 of the separator 30 located in the middle are connected to the other separators 30 located on both sides of the separator 30.

[0042] The first sealing area 31 may be in a “U” shape, and the first sealing area 31 may extend to the outer edge of the partition 30 , or the first sealing area 31 may be spaced a certain distance from the outer edge of the partition 30 .

[0043] In some embodiments, the partition 30 includes a first packaging layer, a second packaging layer and an intermediate layer, wherein the intermediate layer is located between the first packaging layer and the second packaging layer. In some embodiments, the first packaging layer and the second packaging layer are both made of a heat-meltable material, such as PP material.

[0044] In some embodiments, please refer again to Figure 1, the electrochemical device 100 includes a first sealing portion 103, and the shell 10 and the partition 30 are sealed at the first sealing portion 103, that is, the shell 10 and the partition 30 are fixedly connected at the first sealing portion 103 (which can be hot-melt connection or bonding). Among them, the first sealing portion 103 includes a first sealing edge 1031, and the first sealing edge 1031 is a side of the first sealing portion 103 away from the cavity space of the shell 10. In some embodiments, the first sealing portion 103 can be in the shape of a "Hui", that is, the four sides of the shell 10 are used to connect and fix with the partition, and the shell 10 is two parts that can be relatively separated. In addition, the first sealing portion 103 can also be in the shape of a "concave", that is, the shell 10 is two parts connected as one, and each part has a concave cavity space, and the two parts can be interlocked and connected and fixed with the partition. In this embodiment, the shell 10 is formed by a fixed connection of two relatively separable parts.

[0045] In some embodiments, please combine Figures 6 to 8 , along the thickness direction of the first seal portion 103, that is, along the first direction Z, the maximum distance between the pole tabs 22 located in the first seal portion 103 at the first seal edge 1031 is d, the thickness of the electrochemical device is D, and d≤0.4D is satisfied. Among them, the maximum distance d is the distance between the two surfaces of the two pole tabs along the thickness direction of the first seal portion 103, which are farthest apart. In this embodiment, the first pole tab 221 and the second pole tab 222 both extend out of the housing 10 at the first seal edge 1031. When the number of the separator 30 is only one, along the thickness direction of the first seal portion 103, the maximum distance between the pole tabs 22 located in the first seal portion at the first seal edge 1031 can be the distance between the first pole tab 221 and the second pole tab 222 at the first seal edge 1031 in the thickness direction of the first seal portion 103. Exemplarily, d / D can be 0.1, 0.2, 0.3 or 0.4, etc. In a specific example, when D is 3.3 mm, d≤1.32 mm.

[0046] The inventors of the present application have found that, since the first pole ear 221 and the second pole ear 222 partially extend out of the shell 10 from the first sealing portion 103 for connection with the outside, the area of ​​the first pole ear 221 and the second pole ear 222 located in the first sealing portion 103 has thickness, which will affect the packaging effect of the first sealing portion 103. Moreover, at least part of the pole ears of multiple electrode assemblies in different cavities need to extend out of the shell 10, and the thickness of multiple pole ears is continuously accumulated, which further affects the reliability of the seal of the first sealing portion 103. The inventors of the present application have found through research that when the maximum distance d between the first pole ear 221 and the second pole ear 222 at the first sealing edge 1031 along the thickness direction of the first sealing portion 103 satisfies d≤0.4D, the first sealing portion 103 can have a higher packaging reliability. This is because satisfying the above relationship is conducive to the appropriate flatness of the packaging plane of the first sealing part 103. At the same time, the side wall of the shell 10 can provide appropriate strain for the packaging of the under-pressure part of the first sealing part 103, promote the packaging between the shell 10 and the partition 30 at the under-pressure part, thereby improving the packaging reliability of the first sealing part 103.

[0047] In some embodiments, at least one of the following relationships is satisfied: (1) d≤0.15D; (2) d≤2 mm. When at least one of the above relationships is satisfied, the flatness of the surface of the first sealing portion can be further improved, thereby improving the uniformity of the pressure at each location when the shell and the partition are packaged at the first sealing portion, thereby further improving the packaging reliability of the first sealing portion 103.

[0048] In some embodiments, see Figure 7 The first pole tab 221 and the second pole tab 222 both extend out of the housing 10 from the first sealing edge 1031. The thickness of the partition 30 is T, i.e. Figure 7 In the first direction Z, the thickness of the partition 30 is T. Fig. 9 As shown, along the length direction of the first sealing edge 1031, that is, the second direction Y, the minimum spacing between the first pole ear 221 and the second pole ear 222 at the first sealing edge 1031 is L, and L / T ≥ 15. For example, L / T can be 15, 20, 25, 30 or 100, etc. In a specific example, when T is 0.2 mm, L ≥ 3 mm.

[0049] The inventor of the present application found that, since the first pole ear 221 and the second pole ear 222 are located on both sides of the partition 30, on the one hand, the arrangement of the pole ears will have a greater impact on the packaging reliability. Compared with the overlapping arrangement of the first pole ear 221 and the second pole ear 222, the staggered arrangement of the first pole ear 221 and the second pole ear 222 can reduce the difference in the sealing thickness at the first sealing portion 103 and improve the packaging reliability at the pole ears; on the other hand, when the first pole ear 221 and the second pole ear 222 are staggered, along the length direction of the first sealing edge 1031, the portion of the partition 30 located between the first pole ear 221 and the second pole ear 222 is bent, and the packaging reliability at this location is affected. The inventor of the present application found through research that when the minimum spacing L between the first pole ear 221 and the second pole ear 222 at the first sealing edge 1031 and the thickness T of the partition 30 meet L / T≥15, the electrochemical device 100 can have a higher packaging reliability. This is because, by satisfying the above relationship, the bending degree of the partition 30 between the pole ears can be effectively reduced, so that the stress and strain it is subjected to is relatively small, and the portion of the partition 30 between the first pole ear 221 and the second pole ear 222 can better fit other components connected thereto during sealing, and when the pole ears are subjected to external stress pulling the partition, it is not easy to peel off, thereby further improving the packaging reliability.

[0050] The inventors of the present application have also found that the thickness of the first pole tab 221 and the second pole tab 222 along the first direction Z and the spacing between the first pole tab 221 and the second pole tab 222 along the second direction Y satisfy a specific relationship, which can further improve the fit of the portion of the separator 30 between the first pole tab 221 and the second pole tab 222 with other components during sealing. Figure 6-8 In one embodiment, the electrochemical device 100 can satisfy at least one of the following relationships: (3) The thickness of the first electrode tab 221 is h 1 , L / h 1 ≥10; (4) The thickness of the second electrode tab 222 is h 2 , L / h 2 ≥10. At this time, the bending degree of the partition 30 between the first pole ear 221 and the second pole ear 222 can be further reduced, so that the stress and strain it is subjected to is smaller, and the fit between the partition 30 between the first pole ear 221 and the second pole ear 222 and other components is further improved, thereby further improving the packaging reliability.

[0051] In other words, in one embodiment, L / h can be set to 15 under the premise that L / T is ≥ 15. 1 ≥10. Or in another embodiment, under the premise of L / T≥15, L / h 2 ≥10. Or in another embodiment, under the premise of L / T≥15, L / h 1≥10, L / h 2 ≥10.

[0052] In a specific example, when the thickness T of the partition 30 is 0.2 mm, h 1 0.1 mm, h 2 When it is 0.1mm, under the condition of L / T≥15, the minimum value of L is 3mm; L / h 1 ≥10, the minimum value of L is 1mm; L / h 2 ≥10, the minimum value of L is 1mm, and the final minimum value of L is 3mm. 1 ≥ 10 and / or L / h 2 When the distance between the first electrode tab 221 and the second electrode tab 222 along the second direction Y is limited by ≥10, the packaging reliability of the electrochemical device 100 can be further guaranteed.

[0053] In one embodiment, the electrochemical device 100 may also satisfy at least one of the following characteristics: (5) L / (h 1 +T)≥5; (6)L / (h 2 +T)≥5; at this time, the bending degree of the partition 30 between the first pole ear 221 and the second pole ear 222 can be further reduced, so that the stress and strain it is subjected to is smaller, and the fit between the partition between the first pole ear 221 and the second pole ear 222 and other components is further improved, thereby further improving the packaging reliability.

[0054] In one embodiment, h 1 ≤0.2㎜; and / or h 2 ≤0.2㎜.

[0055] In a specific example, the electrochemical device 100 satisfies conditions (5) and (6) at the same time. 1 0.2 mm, h 2 When L / T is 0.2 mm, the minimum value of L is 3 mm under the condition of L / T ≥ 15; L / (h 1 +T)≥5, the minimum value of L is 2mm; L / (h 2 +T)≥5, the minimum value of L is 2mm. Comprehensively speaking, the final minimum value of L is 3mm.

[0056] In a further embodiment, L≥3 mm; and / or T≤0.3 mm. When T≤0.3 mm, the thickness of the separator 30 can be kept small, and the separator 30 can reduce the space occupied by the electrochemical device 100, thereby reducing the energy density of the electrochemical device 100.

[0057] The present application also provides an electronic device 200, which includes the electrochemical device 100 provided in the present application. The electronic device 200 of the present application is not particularly limited, and it can be any electronic device known in the prior art. For example, the electronic device 200 includes but is not limited to a laptop computer, a pen-input computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large household battery and a lithium-ion capacitor, etc.

[0058] The method for preparing the electrochemical device of the present application is not particularly limited, and any method known in the art may be used. For example, in one embodiment, the present application may be prepared by the following preparation method:

[0059] (1) Preparation of negative electrode sheet: The negative electrode active material, binder and solvent are mixed into a slurry and stirred evenly. The slurry is evenly coated on the negative electrode collector and dried to obtain a single-sided coated negative electrode sheet. The above steps are repeated on the other surface of the negative electrode collector to obtain a double-sided coated negative electrode sheet. Then, it is cold pressed and cut for standby use.

[0060] (2) Preparation of positive electrode sheet: The positive electrode active material, binder, conductive agent and solvent are mixed into a slurry and stirred evenly. The slurry is evenly coated on the positive electrode collector and dried to obtain a single-sided coated positive electrode sheet. The above steps are repeated on the other surface of the positive electrode collector to obtain a double-sided coated positive electrode sheet. Then, it is cold pressed and cut for standby use.

[0061] (3) Preparation of electrolyte: lithium salt and non-aqueous solvent are mixed and stirred to obtain an electrolyte.

[0062] (4) Preparation of electrode assemblies: The structure of the electrode assembly can be a winding structure or a laminated structure, wherein a plurality of negative electrode sheets, separators, and positive electrode sheets are sequentially stacked and fixed to form an electrode assembly with a laminated structure; a negative electrode sheet, separator, and positive electrode sheet are sequentially stacked and wound to form an electrode assembly with a wound structure; each electrode assembly comprises a positive electrode tab and a negative electrode tab; and the above steps are repeated to obtain a plurality of electrode assemblies.

[0063] (5) Partition: Any partition known in the art may be used.

[0064] (6) Electrode assembly: Place the packaging shell in an assembly fixture, then space the electrode assembly and the separator, and lead all the tabs of the electrode assembly out of the packaging shell for subsequent processing. Finally, perform top and side sealing, and leave a liquid injection port.

[0065] (7) Liquid injection packaging: Electrolyte is injected into multiple cavities separately, and then sealed after hot pressing, chemical formation, and degassing.

[0066] (8) Series connection: The positive electrode tab of one electrode assembly and the negative electrode tab of another electrode assembly are connected together by laser welding to achieve series connection, thereby obtaining the final electrochemical device.

[0067] The electrochemical device provided in the present application may include two electrode assemblies or three or more electrode assemblies. The preparation method of the electrochemical device including two electrode assemblies or three or more electrode assemblies may refer to the preparation method of the electrochemical device described above.

[0068] The terms used in this application are generally terms commonly used by those skilled in the art. If there is any inconsistency with commonly used terms, the terms in this application shall prevail.

[0069] Example 1-1

[0070] Preparation of lithium-ion batteries

[0071] (1) Preparation of negative electrode sheet: Mix the negative electrode active materials artificial graphite, conductive carbon black (Super P), and styrene-butadiene rubber (SBR) in a weight ratio of 96:1.5:2.5, add deionized water, prepare a slurry with a solid content of 70wt%, and stir evenly. The slurry is evenly coated on one surface of the negative electrode collector copper foil, dried, and a negative electrode sheet coated with a negative electrode active material layer on one side is obtained. Repeat the above steps on the other surface of the negative electrode collector copper foil to obtain a negative electrode sheet coated with a negative electrode active material layer on both sides. After cold pressing, the negative electrode sheet is cut into a size of 41mm×61mm for standby use.

[0072] (2) Preparation of positive electrode sheet: The positive electrode active material lithium cobalt oxide (LiCoO 2 ), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) is added to prepare a slurry with a solid content of 75wt%, and stirred evenly. The slurry is evenly coated on one surface of the positive electrode collector aluminum foil, dried, and a positive electrode sheet coated with a positive electrode active material layer on one side is obtained. On the other surface of the positive electrode collector aluminum foil, the above steps are repeated to obtain a positive electrode sheet coated with a positive electrode active material layer on both sides. After cold pressing, the positive electrode sheet is cut into a specification of 38mm×58mm for standby use.

[0073] (3) Preparation of electrolyte: In a dry argon atmosphere, organic solvents ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed at a mass ratio of EC:EMC:DEC = 30:50:20, and then lithium salt lithium hexafluorophosphate (LiPF4) was added to the organic solvent. 6 ) and mix well to obtain LiPF based on the mass of the electrolyte. 6 The concentration of electrolyte is 12.5%.

[0074] (4) Preparation of the first electrode assembly and the second electrode assembly: The separator, the negative electrode sheet, the separator, and the positive electrode sheet are stacked in sequence to form a laminate structure, and then the four corners of the entire laminate structure are fixed for use. Each electrode assembly includes a positive electrode tab and a negative electrode tab. The positive electrode tab is aluminum (Al) and the negative electrode tab is nickel (Ni). The two tabs are arranged side by side. The thickness h of the positive and negative electrode tabs is 0.2 mm, and the width of the tabs is 5 mm. The separator is a polyethylene (PE) film with a thickness of 15 μm.

[0075] (5) Preparation of the partition: The encapsulation layer material polypropylene (PP, melting point 140°C) is uniformly dispersed in the dispersant N-methylpyrrolidone (NMP) to prepare a PP suspension; the PP suspension is coated on both sides of an aluminum layer with a thickness of 50 μm using a glue coating machine; and then the partition is dried at 130°C, wherein the thickness of the PP encapsulation layer on one side of the aluminum layer is 25 μm, and the total thickness T of the partition is 100 μm.

[0076] (6) Assembly of electrode assembly: Place the aluminum-plastic film (thickness of 150 μm) formed by punching holes in an assembly fixture, with the pit side facing upward, place the first electrode assembly in the pit, and set the pole ear glue in the area corresponding to the pole ear of the first electrode assembly at the edge of the aluminum-plastic film, then place the separator on the first electrode assembly so that the edges are aligned, and apply external force to compact to obtain an assembled semi-finished product. Place the assembled semi-finished product in an assembly fixture, with the separator side facing upward, place the second electrode assembly on the separator so that the edges are aligned, and apply external force to compact, then cover another aluminum-plastic film formed by punching holes with the pit side facing downward on the second electrode assembly, and set the pole ear glue in the area corresponding to the pole ear of the second electrode assembly at the edge of the aluminum-plastic film. Lead the positive and negative pole ears of the first electrode assembly and the second electrode assembly out of the aluminum-plastic film, and use hot pressing to perform top and side sealing to obtain an assembled electrode assembly. Among them, the spacing L between the negative pole ear of the first electrode assembly and the positive pole ear of the second electrode assembly is 5 mm.

[0077] (7) Liquid injection packaging: The electrolyte is injected into each cavity separately, and then sealed after hot pressing, formation, and degassing.

[0078] (8) Series connection: The negative electrode tab of the first electrode assembly and the positive electrode tab of the second electrode assembly are connected together by laser welding to achieve series connection, and the lithium-ion battery is assembled. The thickness D of the lithium-ion battery is 2.5 mm; the height difference d of the tabs on the same side is 1 mm.

[0079] Example 1-2

[0080] The difference from Example 1-1 is that the thickness D of the lithium ion battery is 3.3 mm.

[0081] Examples 1-3

[0082] The difference from Example 1-1 is that the thickness of the aluminum layer in the separator is 20 μm, the thickness of the PP packaging layer on one side of the aluminum layer is 15 μm, and the total thickness T of the separator is 50 μm; the thickness D of the lithium-ion battery is 3.3 mm; and the height difference d of the same-side tabs is 0.66 mm.

[0083] Examples 1-4

[0084] The difference from Example 1-3 is that the thickness D of the lithium-ion battery is 10 mm; and the height difference d of the tabs on the same side is 0.5 mm.

[0085] Examples 1-5

[0086] The difference from Example 1-1 is that the height difference d of the tabs on the same side is 0.6 mm.

[0087] Examples 1-6

[0088] The difference from Example 1-1 is that the thickness D of the lithium-ion battery is 3.3 mm; and the height difference d of the tabs on the same side is 0.6 mm.

[0089] Examples 1-7

[0090] The difference from Example 1-3 is that the height difference d of the tabs on the same side is 0.5 mm.

[0091] Examples 1-8

[0092] The difference from Example 1-3 is that the thickness D of the lithium-ion battery is 6 mm; and the height difference d of the tabs on the same side is 0.6 mm.

[0093] Examples 1-9

[0094] The difference from Example 1-3 is that the thickness D of the lithium-ion battery is 10 mm; and the height difference d of the tabs on the same side is 1.0 mm.

[0095] Examples 1-10

[0096] The difference from Example 1-1 is that the thickness D of the lithium ion battery is 10 mm.

[0097] Embodiment 1-11

[0098] The difference from Example 1-1 is that the thickness of the aluminum layer in the separator is 100 μm, the thickness of the PP packaging layer on one side of the aluminum layer is 25 μm, and the total thickness T of the separator is 150 μm; the thickness D of the lithium-ion battery is 10 mm; and the height difference d of the same-side tabs is 2 mm.

[0099] Comparative Example 1-1

[0100] The difference from Example 1-1 is that the thickness D of the lithium-ion battery is 4 mm; and the height difference d of the tabs on the same side is 2 mm.

[0101] Test method:

[0102] Package reliability test:

[0103] The packaging area sample with a width of 8 mm was cut from the non-tab area at the top seal position (tab extension side). A multifunctional tensile tester was used to clamp the shell and partition on one side of the packaging area. The tensile speed was 50 mm / min. The peeling force P was obtained. 1 , then the packaging strength F=P 1 / 8mm.

[0104] Table 1 Packaging strength test of different tab height difference d and lithium-ion battery thickness D

[0105]

[0106]

[0107] From the comparison of Examples 1-1 to 1-11 in Table 1 with Comparative Example 1-1, it can be seen that when d≤0.4D, the non-ear area of ​​the lithium-ion battery has significantly improved packaging strength. The possible reason is that when d≤0.4D is satisfied, the surface flatness of the seal portion can be improved, and the risk of weak packaging strength due to local undervoltage in the non-ear area when the shell and the partition are packaged at the seal portion due to excessive height difference of the ear in the thickness direction of the seal portion is reduced. At the same time, when d≤0.4D, the side wall of the shell can provide appropriate strain for the packaging at the undervoltage of the seal portion, promote the packaging between the shell and the partition at the undervoltage, thereby improving the reliability of the packaging.

[0108] Example 2-1

[0109] The difference from Example 1-11 is that the thickness of the aluminum layer in the separator is 100 μm, the thickness of the PP packaging layer on one side of the aluminum layer is 50 μm, and the total thickness T of the separator is 0.2 mm.

[0110] The difference between Example 2-2 and Example 2-1 is that L is adjusted to 3 mm and h is adjusted to 0.1 mm.

[0111] The difference between Example 2-3 and Example 2-1 is that L is adjusted to 4 mm; the thickness of the aluminum layer in the partition is 50 μm, the thickness of the single-layer PP packaging layer is 25 μm, the total thickness T of the partition is 0.1 mm; and h is 0.3 mm.

[0112] The difference between Example 2-4 and Example 2-1 is that L is adjusted to 4 mm and h is adjusted to 0.3 mm.

[0113] The difference between Example 2-5 and Example 2-3 is that L is adjusted to 10 mm and h is adjusted to 0.1 mm.

[0114] The difference between Example 2-6 and Example 2-3 is that L is adjusted to 3 mm and h is adjusted to 0.2 mm.

[0115] The difference between Example 2-7 and Example 2-1 is that the negative electrode tab of the first electrode assembly and the positive electrode tab of the second electrode assembly are adjusted to overlap and lead out, that is, L is 0 mm.

[0116] The difference between Example 2-8 and Example 2-1 is that L is adjusted to 2 mm; the thickness of the aluminum layer in the partition is 200 μm, the thickness of the single-sided PP packaging layer is 50 μm, and the total thickness D of the partition is 0.3 mm.

[0117] The difference between Example 2-9 and Example 2-6 is that L is adjusted to 1 mm.

[0118] Bending stability test:

[0119] The two connected tabs are subjected to a 360° bending test, that is, the tabs are bent toward the YZ surface of the electrochemical device (the YZ surface is as shown in the figure) with the top seal area of ​​the separator and the packaging shell as the axis. Figure 1 The connecting tab is bent by bending the YZ surface (as shown) until the connecting tab is in contact with the YZ surface, which is recorded as one bend. Then it is bent 360° in the opposite direction to contact the YZ surface on the other side of the electrochemical device, which is recorded as a second bend. This is repeated until a crack appears at the outer edge of the seal between the two tabs, and the corresponding number of tab bends is recorded.

[0120] Table 2 Bending stability test results of Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-3

[0121]

[0122] The tab thickness h in the above table refers to the thickness h1 of the positive tab and the thickness h2 of the negative tab, that is, the thickness of the positive tab and the thickness of the negative tab remain consistent.

[0123] By comparing Examples 2-1 to 2-6 and Examples 2-7 to 2-9 in Table 2, it can be seen that when L / T ≥ 15, the obtained lithium-ion battery has better bending stability. This is because, on the one hand, the first pole ear and the second pole ear are staggered, which can reduce the difference in seal thickness at the top seal and improve the packaging reliability at the pole ear compared to Example 2-7 in which the first pole ear and the second pole ear are overlapped; on the other hand, by satisfying the above relationship, the bending degree of the partition between the pole ears can be effectively reduced, so that the stress and strain it is subjected to is relatively small, and the partition at the side corner of the pole ear can better fit other components connected to it during sealing, and it is not easy to peel off when the pole ear is pulled by external stress, thereby further improving the packaging reliability.

[0124] It should be noted that the preferred embodiments of the present application are given in the specification and drawings of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described in the specification. These embodiments are not used as additional limitations on the content of the present application. The purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. In addition, the above-mentioned technical features continue to be combined with each other to form various embodiments not listed above, which are all regarded as the scope of the description of the present application; further, for ordinary technicians in this field, they can be improved or transformed according to the above description, and all these improvements and transformations should belong to the scope of protection of the claims attached to the present application.

Claims

1. An electrochemical device, characterized in that: include: A housing, comprising a first housing and a second housing; at least one partition disposed between the first shell and the second shell; The electrochemical device is provided with at least two cavities between the first shell and the second shell; At least two electrode assemblies, each electrode assembly comprising a pole piece assembly and at least two pole ears connected to the pole piece assembly, and each pole piece assembly is respectively accommodated in one of the cavities; The electrochemical device comprises a first sealing portion, the first sealing portion comprises a first sealing edge; along the thickness direction of the first sealing portion, the maximum distance between the pole ears located at the first sealing edge of the first sealing portion is d, the thickness of the electrochemical device is D, and satisfies: d≤0.15D, and d≤2mm, and the maximum distance is the distance between the two surfaces of the two pole ears that are farthest apart along the thickness direction of the first sealing portion; The at least two electrode assemblies include a first electrode assembly and a second electrode assembly that are adjacent to each other, the separator includes a first separator located between the first electrode assembly and the second electrode assembly, the electrode ears of the first electrode assembly include a first electrode ear, the electrode ears of the second electrode assembly include a second electrode ear adjacent to the first electrode ear, along the length direction of the first sealing edge, the distance between the first electrode ear and the second electrode ear at the first sealing edge is L, the thickness of the first separator is T, and L / T≥15.

2. The electrochemical device according to claim 1, characterized in that At least two tabs of at least one electrode assembly extend from a first side end of the shell, and at least two tabs of at least one electrode assembly extend from a second side end of the shell, and the first side end is adjacent to or opposite to the second side end.

3. The electrochemical device according to claim 2, characterized in that At least two tabs of at least one of the electrode assemblies extend from a first side end and a second side end of the shell, respectively.

4. The electrochemical device according to claim 1, characterized in that The partition includes a first encapsulation layer, a second encapsulation layer, and an intermediate layer, wherein the intermediate layer is located between the first encapsulation layer and the second encapsulation layer.

5. The electrochemical device according to claim 1, characterized in that Satisfies at least one of the following characteristics: (1) The thickness of the first electrode tab is h1, L / h1≥10; (2) The thickness of the second electrode tab is h2, L / h2≥10.

6. The electrochemical device according to claim 5, characterized in that Satisfies at least one of the following characteristics: (3) L / (h1+T)≥5; (4) L / (h2+T)≥5; (5) h1≤0.2mm; (6) h2≤0.2mm.

7. The electrochemical device according to any one of claims 1 to 6, characterized in that: The pole piece assembly includes at least one of a winding structure or a stacked structure.

8. An electronic device, characterized in that: Comprising the electrochemical device according to any one of claims 1 to 7.

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