Battery cell, electrochemical device, and electronic device

Abstract

The application discloses an electric core, an electrochemical device and an electronic device, and relates to the technical field of electrochemical energy storage. The electric core comprises a first structure and a second structure arranged along a first direction of the electric core, the projection area of the first structure along the first direction is smaller than the projection area of the second structure along the first direction, the electric core further comprises a plurality of positive electrode sheets and one negative electrode sheet; the negative electrode sheet comprises a plurality of straight line segments and a plurality of bending segments arranged in a stack along the first direction, adjacent straight line segments are connected through a bending segment, the straight line segments comprise a plurality of first straight line segments located in the first structure and a plurality of second straight line segments located in the second structure, the positive electrode sheets comprise first positive electrode sheets and second positive electrode sheets, the first positive electrode sheets are arranged between two adjacent first straight line segments and between adjacent first straight line segments and second straight line segments, and the second positive electrode sheets are arranged between two adjacent second straight line segments. The electric core of the application can avoid introducing a connecting piece.

Description

Technical Field

[0001] This application relates to the field of electrochemical energy storage technology, and in particular to battery cells, electrochemical devices and electronic equipment. Background Technology

[0002] Rechargeable lithium-ion batteries have been gradually applied to various aspects of people's daily lives, such as wearable products, computer products, and medical products. As various products are increasingly developing towards lighter and smaller sizes, battery compartments are no longer limited to regular rectangular or cubic spaces. They can be designed as irregular structures to fit the remaining space inside the product, and the batteries also need to be designed as adaptable irregular structures to maximize capacity.

[0003] In existing technologies, to accommodate different battery compartment spaces, connectors are often used to fix battery cells of different shapes and sizes into a single integrated cell. In this case, the connectors occupy part of the thickness space, leading to a loss of battery energy density. Utility Model Content

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a battery cell that avoids the energy density reduction and structural redundancy caused by introducing connectors by continuously folding an integrated negative electrode sheet to form a stacked structure with different straight segment lengths.

[0005] This application also proposes another type of battery cell.

[0006] This application also proposes an electrochemical device having any of the above-mentioned battery cells.

[0007] This application also proposes an electronic device having the above-described electrochemical device.

[0008] According to a first aspect embodiment of the present application, a battery cell includes a first structure and a second structure arranged along a first direction of the battery cell. The area of ​​the projected region of the first structure along the first direction is smaller than the area of ​​the projected region of the second structure along the first direction. The battery cell also includes a plurality of positive electrode plates and a negative electrode plate. The negative electrode includes multiple straight segments and multiple bent segments stacked along a first direction. Adjacent straight segments are connected by a bent segment. The straight segments include multiple first straight segments located in the first structure and multiple second straight segments located in the second structure. The positive electrode includes a first positive electrode and a second positive electrode. The first positive electrode is disposed between two adjacent first straight segments and between adjacent first straight segments and second straight segments. The second positive electrode is disposed between two adjacent second straight segments.

[0009] The battery cell according to the embodiments of this application has at least the following beneficial effects: This application's battery cell achieves integrated irregularly shaped cells by continuously folding an integrated negative electrode sheet into a stacked structure with different straight segment lengths. Different lengths of positive electrode sheets are then inserted into different structures, thus realizing the integration of irregularly shaped cells and avoiding the energy density reduction and structural redundancy caused by connectors in traditional spliced ​​irregularly shaped cells. Furthermore, since the negative electrode sheet can be continuously formed without cutting, it not only reduces material loss during manufacturing but also improves cell production efficiency and reduces the risk of burrs from electrode cutting, increasing battery safety. This application uses the negative electrode sheet as the main structure for continuous folding, which creates space to wrap the positive electrode sheet during folding and restricts at least one side of the positive electrode sheet. Specifically, the bending segment limits the length of the positive electrode sheet to prevent it from exceeding the range of the negative electrode sheet, thus avoiding the risk of lithium plating.

[0010] According to some embodiments of this application, the negative electrode sheet includes a negative current collector and a negative active layer coated on both sides of the negative current collector, wherein the negative current collector includes an intermediate layer and a conductive layer connected to both sides of the intermediate layer. According to some embodiments of this application, the thickness H1 of the intermediate layer and the thickness H2 of the conductive layer have the following relationship: 1.5≤H1 / H2≤8. According to some embodiments of this application, the positive electrode sheet includes a positive current collector and a positive active layer coated on both sides of the positive current collector, wherein the positive current collector is a metal foil. According to some embodiments of this application, the area of ​​the projected region of the first positive electrode sheet along the first direction is not greater than the area of ​​the projected region of the first straight line segment along the first direction, and / or, the area of ​​the projected region of the second positive electrode sheet along the first direction is not greater than the area of ​​the projected region of the second straight line segment along the first direction. According to some embodiments of this application, the projected area S1 of the first structure along the first direction and the projected area S2 of the second structure along the first direction have the following relationship: 0.25≤S1 / S2≤0.75.

[0011] According to some embodiments of this application, each of the said straight segments is set to extend along a second direction, wherein: The first structure is flush with the second structure along the second direction on one side; Alternatively, the first structure is spaced apart from the corresponding sides of the second structure along the second direction on both sides.

[0012] The battery cell according to a second aspect embodiment of this application includes: Multiple positive electrode plates; A negative electrode includes a plurality of straight segments and a plurality of bent segments stacked along a first direction, adjacent straight segments are connected by a bent segment, and a positive electrode is disposed between two adjacent straight segments; Along the first direction, the length of each straight line segment gradually increases, and the length of each positive electrode sheet gradually increases.

[0013] The electrochemical device according to a third aspect of this application includes the battery cell mentioned in any of the foregoing embodiments.

[0014] An electronic device according to a fourth aspect of this application includes the electrochemical device mentioned in any of the foregoing embodiments.

[0015] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0016] The present application will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of the battery cell structure according to an embodiment of this application; Figure 2 This is a schematic diagram of the battery cell structure according to an embodiment of this application; Figure 3 for Figure 2 Enlarged view of region A in the middle; Figure 4 This is a schematic diagram of the structure of a battery cell according to another embodiment of this application; Figure label: Battery cell 10; First structure 11; Second structure 12; Negative electrode 100; Straight segment 110; First straight segment 111; Second straight segment 112; Bending segment 120; Negative electrode current collector 130; Intermediate layer 131; Conductive layer 132; Negative electrode active layer 140; Positive electrode 200; Positive current collector 201; Positive active layer 202; First positive electrode 210; Second positive electrode 220; Diaphragm 300; Detailed Implementation To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. The embodiments of this application may omit unnecessary detailed descriptions. For example, detailed descriptions of well-known matters and repeated descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art.

[0017] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0018] As used herein, the terms “approximately,” “generally,” “substantially,” and “about” are used to describe and indicate small variations. When used in conjunction with an event or situation, the terms may refer to examples in which the event or situation occurred precisely and examples in which the event or situation occurred very approximately. For example, when used in conjunction with numerical values, the terms may refer to a range of variation less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, if the difference between two numerical values ​​is less than or equal to ±10% of the average of the values ​​(e.g., less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%), then the two numerical values ​​can be considered “generally” the same.

[0019] Furthermore, for ease of description, "first," "second," "third," etc., can be used in this article to distinguish different components of a figure or a series of figures. "First," "second," "third," etc., are not intended to describe the corresponding components.

[0020] Additionally, quantities, ratios, and other numerical values ​​are sometimes presented in range format in this document. It should be understood that such range format is for convenience and brevity and should be interpreted flexibly to include not only the numerical values ​​explicitly specified as range limits, but also all individual numerical values ​​or subranges covered within the range, as if each numerical value and subrange were explicitly specified.

[0021] In the detailed description and claims, a list of items connected by the terms "one of," "among," "a kind of," or other similar terms may mean any of the listed items. For example, if items A and B are listed, then the phrase "one of A and B" means only A or only B. In another example, if items A, B, and C are listed, then the phrase "one of A, B, and C" means only A; only B; or only C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0022] In the detailed description and claims, the list of items connected by the term "at least one of" can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C.

[0023] In the following description, all figures disclosed in this application are approximate values, regardless of whether the terms "about" or "approximately" are used in conjunction. They may vary by 1%, 2%, 5%, or sometimes 10% to 20%. Whenever a range of values ​​with a lower limit (RL) and an upper limit (RU) is disclosed, any values ​​falling within that range are specifically disclosed. Specifically, the following values ​​within this range are specifically disclosed: R = RL + k * (RU - RL), where k is a variable with a 1% increment from 1% to 100%, i.e., k is 1%, 2%, 3%, 4%, 5%, ..., 50%, 51%, 52%, ..., 95%, 96%, 97%, 98%, 99%, or 100%. Furthermore, any range of values ​​defined by the two R values ​​as defined above are also specifically disclosed.

[0024] Throughout this specification, references to “implementation,” “partial implementation,” “one implementation,” “another approach,” “specific approach,” or “partial approach” mean that at least one implementation or embodiment in this application includes the specific features, structures, materials, or characteristics described in that implementation or embodiment.

[0025] In this application, numerical ranges are involved. Unless otherwise specified, the numerical ranges mentioned above are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Any lower limit can be combined with any upper limit to form a range not explicitly stated; and any lower limit can be combined with other lower limits to form a range not explicitly stated, just as any upper limit can be combined with any other upper limit to form a range not explicitly stated. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form a range not explicitly stated.

[0026] Rechargeable lithium-ion batteries have been gradually applied to various aspects of people's daily lives, such as wearable products, computer products, and medical products. As various products are increasingly developing towards lighter and smaller sizes, battery compartments are no longer limited to regular rectangular or cubic spaces. They can be designed as irregular structures to fit the remaining space inside the product, and the batteries also need to be designed as adaptable irregular structures to maximize capacity.

[0027] In existing technologies, to accommodate different battery compartment spaces, connectors are often used to fix battery cells of different shapes and sizes into a single integrated cell. In this case, the connectors occupy part of the thickness space, leading to a loss of battery energy density.

[0028] To address the aforementioned problems, this application proposes a structure for a battery cell 10. This battery cell 10 has an irregular shape design, including a first structure 11 and a second structure 12 arranged along a first direction of the battery cell 10, as shown below. Figure 1 As shown, the first structure 11 and the second structure 12 are rectangular bodies of different sizes. The area of ​​the projection region of the first structure 11 along the first direction is smaller than the area of ​​the projection region of the second structure 12 along the first direction. This can form a stepped structure or a convex structure to adapt to the spatial layout of irregular battery compartments and improve space utilization.

[0029] It should be noted that the irregularly shaped battery cell 10 is not a structure assembled from multiple independent battery cells through connectors, but an integral battery cell 10 prepared by an integrated molding process. The irregularly shaped structural design can be achieved without additional connectors, thereby avoiding the space occupation and energy density loss caused by connectors.

[0030] Specifically, the battery cell 10 includes multiple positive electrode plates 200 and one negative electrode plate 100. The negative electrode plate 100 of this application is formed by continuous folding to create multiple straight segments 110 and bent segments 120. Each straight segment 110 is stacked along a first direction, and adjacent straight segments 110 are connected by a bent segment 120. For ease of description, the extension direction of each straight segment 110 is defined as a second direction. One end of the same straight segment 110 along the second direction is connected to the preceding adjacent straight segment 110 via a bent segment 120, and the other end is connected to the following adjacent straight segment 110 via another bent segment 120, thereby forming an S-shaped continuous folding structure. The positive electrode plates 200 are respectively embedded between each straight segment 110 of the negative electrode plate 100 and are arranged sequentially along the first direction.

[0031] More specifically, during the continuous folding process, the length of the straight segment 110 of the negative electrode 100 is adjusted according to the size requirements of the first structure 11 and the second structure 12. For example... Figure 2 As shown, the straight segment 110 includes a first straight segment 111 located in the first structure 11 and a second straight segment 112 located in the second structure 12. The length of the first straight segment 111 along the second direction is less than the length of the second straight segment 112. The positive electrode 200 correspondingly includes a first positive electrode 210 and a second positive electrode 220. The length of the first positive electrode 210 along the second direction is less than the length of the second positive electrode 220.

[0032] In such Figure 2 In the illustrated embodiment, each of the first straight segments 111 is of equal length, and the first positive electrode 210 is disposed between two adjacent first straight segments 111; each of the second straight segments 112 is also of equal length, and the second positive electrode 220 is disposed between two adjacent second straight segments 112. It can be understood that at the junction of the first structure 11 and the second structure 12, the first positive electrode 210 is disposed between adjacent first straight segments 111 and second straight segments 112, thereby fully utilizing the space at the junction of the first structure 11 and the second structure 12 for electrochemical reactions, further improving the overall energy density of the cell 10.

[0033] Based on the above, the battery cell 10 of this application achieves the integration of irregularly shaped battery cells 10 by continuously folding an integrated negative electrode sheet 100 to form a stacked structure with different lengths of straight segments 110, and then inserting positive electrode sheets 200 of different lengths for different structures. This avoids the energy density reduction and structural redundancy caused by the introduction of connectors in traditional spliced ​​irregularly shaped battery cells 10. In addition, since the negative electrode sheet 100 can be continuously formed without cutting, it not only reduces material loss during the manufacturing process, but also improves the production efficiency of the battery cell 10, and reduces the risk of burrs caused by electrode cutting, thereby increasing the battery safety factor.

[0034] It should be noted that this application uses the negative electrode 100 as the main structure for continuous folding, which can form a space for wrapping the positive electrode 200 during folding and form a restriction on at least one side of the positive electrode 200. Specifically, the setting of the bending section 120 can limit the length of the positive electrode 200 to avoid the positive electrode 200 from exceeding the range of the negative electrode 100 and causing the risk of lithium plating.

[0035] In addition, such as Figure 2 As shown, the separator 300 also needs to be continuously folded along with the negative electrode 100. Separators 300 are provided on both sides of the negative electrode 100 to separate the negative electrode 100 and the positive electrode 200.

[0036] like Figure 3 As shown, the negative electrode 100 includes a negative electrode current collector 130 and a negative electrode active layer 140 coated on both sides of the negative electrode current collector 130. It is understood that the negative electrode current collector 130 can be a copper foil of uniform thickness or other conductive material, with its surface coated with graphite or silicon-based material as the negative electrode active layer 140. In other embodiments, the negative electrode current collector 130 can also be a composite current collector structure, including an intermediate layer 131 made of polymer material and conductive layers 132 connected to both sides of the intermediate layer 131. This composite current collector has good toughness, preventing the performance degradation and safety risks caused by the breakage of the bent section 120 of the negative electrode 100 under pressure. Simultaneously, the composite current collector also has puncture resistance, effectively reducing the risk of internal short circuits caused by external punctures and improving the overall safety level of the battery.

[0037] Understandably, the material of the intermediate layer 131 can be polymethyl methacrylate, polyethylene, polyvinylidene fluoride, polytetrafluoroethylene, polypropylene, polyacrylonitrile, polystyrene, polyacrylamide, polyimide, polyurethane, styrene-butadiene rubber, aramid, carbon fiber cloth, polyaniline, etc. To improve the conductivity of the intermediate layer 131, conductive materials, such as carbon fiber, graphene, carbon nanotubes, carbon black (SP), conductive graphite, or one or more related composites, can be doped into the polymer material. The doped intermediate layer 131 not only retains the flexibility of the original polymer material but also further enhances the overall conductivity of the composite current collector, thereby effectively reducing the battery's internal resistance and improving charge and discharge efficiency.

[0038] Furthermore, the thickness H1 of the intermediate layer 131 and the thickness H2 of the conductive layer 132 have the following relationship: 1.5 ≤ H1 / H2 ≤ 8. The thickness of the intermediate layer 131 can be any value from 3 μm to 5 μm. For example, the thickness of the intermediate layer 131 can be 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, etc., or fall within the range of any two of the above values. The thickness of the conductive layer 132 can be any value from 0.5 μm to 2 μm. For example, the thickness of the conductive layer 132 can be 0.5 μm, 0.7 μm, 1.0 μm, 1.5 μm, 2.0 μm, etc., or fall within the range of any two of the above values. When H1 / H2 < 1.5, the conductive layer 132 has an excessively large thickness, while the intermediate layer 131 has an insufficient thickness, which can easily lead to insufficient toughness of the current collector, causing cracks during bending and affecting structural integrity. When H1 / H2 > 8, an excessively thick intermediate layer 131 will weaken conductivity and increase internal resistance. Furthermore, the mass ratio of conductive material doped in the intermediate layer 131 should be controlled between 10% and 15%; too high a ratio will affect flexibility, while too low a ratio will have limited effect on improving conductivity.

[0039] In some embodiments, the positive electrode 200 includes a positive current collector 201 and a positive active layer 202 coated on both sides of the positive current collector 201. The positive current collector 201 can be a composite current collector structure, which also includes an intermediate layer 131 made of polymer material and conductive layers 132 on both sides. Unlike the negative current collector 130, the conductive layer 132 of the positive current collector 201 is made of aluminum or aluminum-based alloy material. It is understood that the positive electrode 200 with a composite structure has better toughness and safety performance.

[0040] In this embodiment, since the positive electrode current collector 201 does not need to be bent, the toughness requirement for the positive electrode current collector 201 is not high. The positive electrode current collector 201 can be made of metal foil without the need for a composite structure. For example, the positive electrode current collector 201 is aluminum foil. This type of current collector has a small thickness, which can effectively reduce the thickness space occupied by the current collector, thereby improving the overall energy density of the battery.

[0041] like Figure 2As shown, the length of the first straight segment 111 along the second direction is less than the length of the second straight segment 112 along the second direction. Correspondingly, the length of the first positive electrode 210 along the second direction is less than the length of the second positive electrode 220. In some embodiments, the projected area of ​​the first positive electrode 210 along the first direction is not greater than the projected area of ​​the first straight segment 111 along the first direction, so that the first positive electrode 210 is completely within the coverage of the first straight segment 111, avoiding uneven current distribution caused by misalignment, and reducing the risk of lithium dendrite growth caused by edge effects, further improving battery cycle life and safety. Similarly, the projected area of ​​the second positive electrode 220 along the first direction is not greater than the projected area of ​​the second straight segment 112 along the first direction, ensuring that it is completely within the coverage of the second straight segment 112.

[0042] In some embodiments, the projected area S1 of the first structure 11 along the first direction and the projected area S2 of the second structure 12 along the first direction have the following relationship: 0.25 ≤ S1 / S2 ≤ 0.75. Within this range, the deformation resistance and heat dissipation efficiency of the battery cell 10 can be effectively improved. If S1 / S2 < 0.25, the first structure 11 exhibits a narrow and tall structure, and the deformation resistance of the battery is weakened; if S1 / S2 > 0.75, the first structure 11 is close to the second structure 12 in the width direction, thereby reducing the heat dissipation inside the battery and increasing the risk of thermal runaway.

[0043] In such Figure 1 In the embodiment shown, one side of the first structure 11 along the second direction is flush with one side of the second structure 12 along the second direction, so that the battery cell 10 has a stepped structure, as shown in the figure. Figure 4 In the illustrated embodiment, the first structure 11 is spaced apart from the corresponding sides of the second structure 12 along the second direction, that is, the first structure 11 is located in the middle region of the second structure 12, thus forming a U-shaped structure with a central protrusion. It is understood that the aforementioned irregularly shaped battery cells 10 can be flexibly selected according to actual packaging requirements and spatial layout.

[0044] It is understood that this application may also include a third structure, a fourth structure, etc., arranged with the first structure 11 and the second structure 12, in order to realize a multi-layer structure stacking design and match different space requirements.

[0045] The present application and its beneficial effects will be further described in detail below with reference to embodiments, but the implementation of the present application is not limited thereto: Fabrication of the positive electrode sheet: The cathode active material LiCoO2, conductive agent acetylene black, conductive carbon nanotubes, and binder polyvinylidene fluoride (PVDF) are fully dispersed and uniformly coated onto both sides of the positive current collector (aluminum foil) in an N-methylpyrrolidone solvent system at a weight ratio of 97.6:0.5:0.6:1.3. Then, the positive electrode sheet is dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0046] Fabrication of negative electrode sheet: Anode active material (graphite / silicon carbide), conductive agent, and binder are mixed in a weight ratio of 97.7:1.1:1.2 to obtain an anode slurry that is uniformly coated on both sides of the negative current collector. Then, the mixture is dried, cold-pressed, and slit to obtain the negative electrode sheet.

[0047] Separator: A ceramic mixture is coated on the surface of PE (polyethylene) to serve as a separator.

[0048] Electrolyte: Ethyl carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), and propyl propionate (PP) are mixed in a volume ratio of 1.2:1:4:4. Then, fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent at a ratio of 1 mol / L to prepare the electrolyte.

[0049] Full cell preparation: The above-mentioned positive electrode sheet, separator, and negative electrode sheet are wound to form the irregular cell structure as described in the above embodiments, and then packaged and injected with electrolyte to produce a finished lithium-ion battery.

[0050] The batteries in Examples 1-5 and Comparative Examples 1-3 were all prepared according to the above method. The main difference lies in some parameters. The specific parameter differences are shown in the table below. In addition, a battery made of a conventional stacked cell is also provided as Comparative Example 4.

[0051]

[0052] The K-value test and thermal shock test were respectively performed on Examples 1-5 and Comparative Examples 1-4; K-value test: At 25℃, adjust the battery voltage to about 3.95V and record the voltage OCV1. After resting for 48 hours, record the voltage OCV2. K value = (OCV1-OCV2) / 48, where K value represents the voltage drop of the battery per unit time. This parameter is of great significance for evaluating the performance and reliability of the battery, because the self-discharge rate directly affects the battery's lifespan and energy storage efficiency.

[0053] Thermal shock test: At room temperature, fully charge the battery cell and let it rest for 1 hour. Place the battery cell in an oven, and raise the oven temperature to the set temperature at a rate of 5±2℃ / min, and maintain it for 60 minutes before stopping. The test is considered passed if the battery cell does not catch fire or explode during the process.

[0054] The test results are shown in the table below:

[0055] The second aspect of this application also proposes an irregularly shaped battery cell 10. The manufacturing concept of the battery cell 10 in the second aspect embodiment is basically the same as that in the first aspect embodiment. Both are achieved by connecting and folding the negative electrode 100 and embedding the positive electrode 200. However, the battery cell 10 in the second aspect embodiment differs from the battery cell 10 in the first aspect embodiment in terms of structure.

[0056] Specifically, the battery cell 10 includes multiple positive electrode plates 200 and one negative electrode plate 100. The negative electrode plate 100 includes multiple straight segments 110 and multiple bent segments 120 stacked along a first direction. Adjacent straight segments 110 are connected by a bent segment 120. The positive electrode plate 200 is disposed between two adjacent straight segments 110. Along the first direction, the length of each straight segment 110 gradually increases, and the length of each positive electrode plate 200 gradually increases. Thus, the entire battery cell 10 presents a trapezoidal structure.

[0057] A third aspect of this application also provides an electrochemical device comprising the battery cell 10 described above. This electrochemical device includes any apparatus that performs an electrochemical reaction to convert chemical energy into electrical energy, and specific, non-limiting examples include all types of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. In particular, the electrochemical device is a lithium secondary battery, including lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, or lithium-ion polymer secondary batteries.

[0058] The fourth aspect of this application also proposes an electronic device that includes the electrochemical device described above. The electronic device described in this application is not particularly limited and can be applied to any electronic device known in the prior art. The use of the electrochemical device described in this application is not particularly limited and can be used in any electronic device known in the prior art. According to some embodiments of this application, the electronic device includes, but is not limited to, mobile phones, smartphones, laptops, tablets, wearable devices, smartwatches, smart bracelets, smart glasses, power banks, televisions, game consoles, game controllers, digital cameras, smart speakers, headphones, keyboards, mice, monitors, drones, audio equipment, home appliances, toys, power tools, automobiles, motorcycles, electric bicycles, bicycles, robots, robot dogs, industrial robots, and android robots.

[0059] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limiting the present application, and that changes, substitutions and modifications can be made to the embodiments without departing from the spirit, principles and scope of the present application.

Claims

1. A battery cell, characterized in that, The battery cell includes a first structure and a second structure arranged along a first direction. The area of ​​the projected region of the first structure along the first direction is smaller than the area of ​​the projected region of the second structure along the first direction. The battery cell also includes a plurality of positive electrode plates and a negative electrode plate. The negative electrode includes multiple straight segments and multiple bent segments stacked along a first direction. Adjacent straight segments are connected by a bent segment. The straight segments include multiple first straight segments located in the first structure and multiple second straight segments located in the second structure. The positive electrode includes a first positive electrode and a second positive electrode. The first positive electrode is disposed between two adjacent first straight segments and between adjacent first straight segments and second straight segments. The second positive electrode is disposed between two adjacent second straight segments.

2. The battery cell according to claim 1, characterized in that, The negative electrode sheet includes a negative current collector and a negative active layer coated on both sides of the negative current collector. The negative current collector includes an intermediate layer and a conductive layer connected to both sides of the intermediate layer.

3. The battery cell according to claim 2, characterized in that, The thickness H1 of the intermediate layer and the thickness H2 of the conductive layer have the following relationship: 1.5≤H1 / H2≤8.

4. The battery cell according to claim 2, characterized in that, The positive electrode sheet includes a positive current collector and a positive active layer coated on both sides of the positive current collector, wherein the positive current collector is a metal foil.

5. The battery cell according to claim 1, characterized in that, The area of ​​the projected region of the first positive electrode along the first direction is not greater than the area of ​​the projected region of the first straight line segment along the first direction, and / or the area of ​​the projected region of the second positive electrode along the first direction is not greater than the area of ​​the projected region of the second straight line segment along the first direction.

6. The battery cell according to claim 1, characterized in that, The projected area S1 of the first structure along the first direction and the projected area S2 of the second structure along the first direction have the following relationship: 0.25≤S1 / S2≤0.

75.

7. The battery cell according to claim 1, characterized in that, Each of the aforementioned straight line segments is defined to extend along a second direction, wherein: The first structure is flush with the second structure along the second direction on one side; Alternatively, the first structure is spaced apart from the corresponding sides of the second structure along the second direction on both sides.

8. A battery cell, characterized in that, include: Multiple positive electrode plates; A negative electrode includes a plurality of straight segments and a plurality of bent segments stacked along a first direction, adjacent straight segments are connected by a bent segment, and a positive electrode is disposed between two adjacent straight segments; Along the first direction, the length of each straight line segment gradually increases, and the length of each positive electrode sheet gradually increases.

9. An electrochemical device, characterized in that, Includes the battery cell as described in any one of claims 1 to 8.

10. An electronic device, characterized in that, Includes the electrochemical device as described in claim 9.

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