Battery cell and battery

Abstract

The utility model discloses a battery cell and a battery, the battery cell comprises a first pole piece which is folded in a folding fan type, the first pole piece forms a plurality of accommodating spaces which are sequentially spaced along the folding direction of the first pole piece, and the openings of any two adjacent accommodating spaces face opposite directions; the diaphragms are attached to two opposite side surfaces of the first pole piece and are folded along with the first pole piece; the polarity of the second pole pieces is opposite to that of the first pole pieces, and each second pole piece is inserted into at least one containing space of the first pole piece. According to the battery cell disclosed by the utility model, the first pole piece is designed into the continuous folding fan type structure to form the accommodating spaces with the openings facing alternately and oppositely, and the second pole pieces are respectively inserted into the different accommodating spaces of the first pole piece from the two sides of the first pole piece, so that when the battery cell is manufactured, only one type of pole piece is required to be inserted; and compared with the existing laminated battery cell production, the step of inserting the pole piece in the technological process is reduced, and the production efficiency can be improved.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery technology, and in particular to a battery cell and battery. Background Technology

[0002] Lithium batteries are batteries that contain lithium (including metallic lithium, lithium alloys, lithium ions, and lithium polymers) in their electrochemical system and are widely used in digital products and other fields.

[0003] The mainstream types of lithium batteries on the market include wound and stacked cells. Among them, stacked cells can better improve battery performance compared to wound cells, and have advantages in energy density and safety.

[0004] Traditional laminated battery cells require repeated insertion of individual anode and cathode electrodes into the separator during manufacturing, resulting in numerous production steps and low production efficiency. Utility Model Content

[0005] The main purpose of this invention is to propose a battery cell that aims to solve, to some extent, the technical problem of low production efficiency in current stacked battery production.

[0006] To achieve the above objectives, this utility model proposes a battery cell, which includes:

[0007] The first electrode is folded in a fan shape, and multiple sequentially spaced accommodating spaces are formed along its folding direction. The openings of any two adjacent accommodating spaces face opposite directions.

[0008] A diaphragm is attached to the opposite sides of the first electrode and is folded along with the first electrode.

[0009] A plurality of second electrodes, having the opposite polarity to the first electrode, are inserted into at least one of the receiving spaces of the first electrode.

[0010] Optionally, the first electrode is constructed to have a plurality of first straight portions and a plurality of first corner portions, the plurality of first straight portions being arranged sequentially along the folding direction of the first electrode, and any two adjacent first straight portions being connected by a first corner portion.

[0011] Optionally, the second electrode is folded in a U-shape to form a second corner portion and two second straight portions, and the two second straight portions are connected by the second corner portion;

[0012] At least one of the second straight portions of each second electrode is inserted into the receiving space of the first electrode.

[0013] Optionally, both the first straight portion and the first corner portion include a first current collector, and the first current collector of the first straight portion is coated with a first active material layer;

[0014] The first active material layer is coated on the opposite two sides of the first current collector in each of the first straight sections.

[0015] Optionally, both the second straight portion and the second corner portion include a second current collector;

[0016] The second current collector of the second straight section is coated with a second active material layer on one side facing the first straight section.

[0017] Optionally, the coating length of the first active material layer is greater than the coating length of the second active material layer; and / or,

[0018] The coating width of the first active material layer is greater than the coating width of the second active material layer.

[0019] Optionally, at least one of the first current collector and the second current collector is a composite current collector.

[0020] Optionally, the battery cell further includes:

[0021] At least one first electrode tab is welded to the first straight portion;

[0022] Multiple second tabs are provided, each of which is welded to the second straight portion of a second electrode sheet. The multiple second tabs are stacked and connected along the folding direction of the first electrode sheet and are spaced apart from the first tabs along the width direction of the cell.

[0023] Optionally, the first electrode is a negative electrode and the second electrode is a positive electrode.

[0024] This utility model also proposes a battery comprising a casing and a battery cell as described above, wherein the battery cell is disposed in the casing.

[0025] In this novel battery cell, the first electrode is designed as a continuous folding fan structure, forming multiple accommodating spaces with alternating opposite opening directions. Multiple second electrodes are inserted into different accommodating spaces of the first electrode from opposite sides. When manufacturing this battery cell, only one type of electrode insertion operation needs to be performed. Compared with the existing stacked battery cell production, the electrode insertion steps in the process are reduced, which can improve production efficiency. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the battery cell structure in one embodiment of the present invention;

[0027] Figure 2 for Figure 1 Exploded view of the battery cell in the embodiment;

[0028] Figure 3 This is a schematic diagram of the battery cell structure in another embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the battery cell structure in another embodiment of the present invention;

[0030] Explanation of reference numerals in the attached figures:

[0031] label name label name 100 First Pole Film R storage space 200 diaphragm 300 Second pole plate 110 First straight section 120 First corner 310 Second corner 320 Second straight section 10 First fluid collector 20 First active substance layer 30 Second fluid 40 Second active substance layer

[0032] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0033] The solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0034] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0035] It should also be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component present. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component present.

[0036] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0037] This utility model embodiment proposes a battery cell, referring to... Figures 1 to 4 The battery cell includes:

[0038] The first electrode 100 is folded in a fan shape, and the first electrode 100 forms a plurality of sequentially spaced accommodating spaces R along its folding direction, with the openings of any two adjacent accommodating spaces R facing opposite directions.

[0039] The diaphragm 200 is attached to the opposite sides of the first electrode 100 and is folded along with the first electrode 100;

[0040] Multiple second electrodes 300, with polarity opposite to that of the first electrode 100, are inserted into at least one accommodating space R of the first electrode 100.

[0041] The battery cell involved in this embodiment comprises a first electrode 100, a separator 200, and a second electrode 300. The first electrode 100 and the second electrode 300 have opposite polarities; one of the first electrode 100 and the second electrode 300 is the negative electrode (i.e., the anode), and the other is the positive electrode (i.e., the cathode). The first electrode 100 adopts a fan-shaped folding structure. This structural design gives the first electrode 100 a certain degree of flexibility and foldability, and also provides the basic framework for subsequent cooperation with the second electrode 300. Specifically, the first electrode 100 is folded in a fan shape to form multiple accommodating spaces R in its folding direction. The number of second electrode 300 can be multiple, i.e., two or more, selected according to actual needs. Each second electrode 300 is inserted into at least one accommodating space R of the first electrode 100. For example, when the second electrode 300 is a rectangular electrode, it can be inserted into one accommodating space R of the first electrode 100. When the second electrode 300 is a folded electrode, it can be inserted into multiple accommodating spaces R of the first electrode 100.

[0042] There can be two separators 200, which are respectively attached to opposite sides of the first electrode 100. Based on the fan-shaped folding design of the first electrode 100, the separators 200 are folded along with the first electrode 100 to separate the first electrode 100 and the second electrode 300 in all directions, avoiding direct contact between the positive and negative electrodes. Furthermore, it ensures a tight fit with the first electrode 100. During the charging and discharging process of the battery cell, even if the electrode undergoes slight deformation due to changes in internal stress, the separators 200 can always maintain an effective isolation function, making it less prone to displacement or damage, thereby ensuring the safety of the battery cell.

[0043] like Figure 1 and Figure 2 As shown, the manufacturing process of this battery cell is as follows:

[0044] First, the diaphragm 200 is attached to the opposite sides of the first electrode 100. Then, the first electrode 100 and the diaphragm 200 are folded together in a fan shape to shape them. Finally, multiple second electrodes 300 are inserted one by one into the receiving space R of the first electrode 100 to achieve a stacked arrangement with the first electrode 100 and the diaphragm 200.

[0045] The first electrode 100 is designed as a continuous folding fan structure, forming multiple accommodating spaces R with alternating opposite opening directions. Multiple second electrodes 300 are respectively inserted into different accommodating spaces R of the first electrode 100 from opposite sides. When manufacturing this cell, only one type of electrode insertion operation needs to be performed. Compared with the existing stacked cell production, the electrode insertion steps in the process are reduced, which can improve production efficiency.

[0046] In some embodiments, refer to Figures 1 to 4 The first electrode 100 is constructed to have a plurality of first straight portions 110 and a plurality of first corner portions 120. The plurality of first straight portions 110 are arranged sequentially along the folding direction of the first electrode 100, and any two adjacent first straight portions 110 are connected by a first corner portion 120.

[0047] In this embodiment, the first electrode 100, due to its fan-shaped folding structure, forms a plurality of first straight portions 110 and a plurality of first corner portions 120. The plurality of first straight portions 110 and the plurality of first corner portions 120 are alternately arranged, meaning that any two adjacent first straight portions 110 are connected by a first corner portion 120, and any two adjacent first corner portions 120 are connected by a first straight portion 110. Furthermore, the plurality of first straight portions 110 are arranged sequentially along the folding direction of the first electrode 100. Adjacent first straight portions 110 and the first corner portion 120 between them form an accommodating space R for the insertion of the second electrode 300.

[0048] In some embodiments, the second electrode 300 is folded in a U-shape to form a second corner portion 310 and two second straight portions 320, and the two second straight portions 320 are connected to each other through the second corner portion 310.

[0049] At least one second straight portion 320 of each second electrode 300 is inserted into the receiving space R of the first electrode 100.

[0050] The second electrode 300 adopts a U-shaped folding structure, correspondingly forming two second straight portions 320 and a second corner portion 310. The second corner portion 310 is located between the two second straight portions 320 to achieve the connection between them. Based on the U-shaped folding structure adopted by the second electrode 300, when it is inserted into the receiving space R of the first electrode 100, depending on the position of the first electrode 100, the second electrode 300 can have one second straight portion 320 inserted into the receiving space R of the first electrode 100, or both second straight portions 320 can be inserted into the receiving space R of the first electrode 100. For example, when the second electrode 300 is inserted at the end position of the first electrode 100 in the folding direction, one of the two second straight portions 320 of the second electrode 300 is inserted into the receiving space R of the first electrode 100; while when the second electrode 300 is inserted at a non-end position (such as the middle position) in the folding direction of the second electrode 300, both of the two second straight portions 320 of the second electrode 300 are inserted into the receiving space R of the first electrode 100, and when both of the two second straight portions 320 of the second electrode 300 are inserted into the receiving space R of the first electrode 100, the two second straight portions 320 are respectively inserted into different receiving spaces R of the first electrode 100.

[0051] After multiple second electrode plates 300 are inserted and engaged with the first electrode plate 100, multiple first straight portions 110 and multiple second straight portions 320 are alternately stacked along the folding direction of the first electrode plate 100, and a portion of the first corner portion 120 of the first electrode plate 100 is wrapped by the second corner portion 310. This unique folding and insertion method of the first electrode plate 100 and the second electrode plate 300 makes the arrangement of the electrodes more compact and orderly, allowing more electrode material to be accommodated within the same volume, thereby increasing the energy density of the battery and improving its overall performance. Furthermore, the wrapping of the first corner portion 120 by the second corner portion 310 enhances the connection stability between the second electrode plate 300 and the first electrode plate 100, reducing displacement and deformation of the electrode plates due to stress during battery charging and discharging, and improving the stability and reliability of the battery structure.

[0052] In some embodiments, refer to Figure 1 and Figure 2 Both the first straight portion 110 and the first corner portion 120 include a first current collector 10, and the first current collector 10 of the first straight portion 110 is coated with a first active material layer 20.

[0053] The first active material layer 20 is coated on the opposite two sides of the first current collector 10 of each first straight portion 110.

[0054] Depending on the type of the first electrode 100, the first current collector 10 and the first active material layer 20 can be made of appropriate materials. For example, when the first electrode 100 is a negative electrode, the first current collector 10 can be made of copper foil, which has good conductivity and ductility and can stably transport electrons. The first active material layer 20 can be made of a negative electrode active coating material, such as graphite, which has a high theoretical specific capacity and can effectively store and release lithium ions during battery charging and discharging, ensuring the normal operation of the battery.

[0055] Specifically, the first current collector 10 of the first straight portion 110 and the first current collector 10 of the first corner portion 120 are integrally formed, and a first active material layer 20 is coated on the first current collector of the first straight portion 110. The first active material layer 20 is coated on the opposite two sides of the first current collector 10 of each first straight portion 110. Since both sides of the first straight portion 110 need to participate in the electrochemical reaction inside the battery, by coating the first current collector 10 of the first straight portion 110 with the first active material layer 20 on both sides, space is fully utilized, the energy density of the battery is increased, and thus the charge and discharge efficiency of the battery is improved. In addition, due to the special structure of the first corner portion 120, it is more susceptible to external forces such as compression and bending than the first straight portion 110. If an active material is coated on the first current collector 10 of the first corner portion 120, the active material may fall off or shift when the battery cell is subjected to these external forces, thereby increasing the risk of short circuit. Therefore, this embodiment can effectively reduce the risk of short circuit and ensure the safe and stable operation of the battery cell by using only the first current collector 10 in the first corner portion 120.

[0056] In some embodiments, refer to Figure 1 and Figure 2 The second straight portion 320 and the second corner portion 310 both include a second current collector 30;

[0057] In this embodiment, the second current collector 30 of the second straight portion 320 is coated with a second active material layer 40 on one side facing the first straight portion 110.

[0058] Depending on the type of the second electrode 300, the second current collector 30 and the second active material layer 40 can be made of appropriate materials. For example, when the second tab is a positive electrode, the second current collector 30 can be made of aluminum foil, which has good conductivity and light weight, and can reduce the overall weight of the battery while ensuring battery performance. The second active material layer 40 can be made of a positive electrode active coating material, such as lithium cobalt oxide.

[0059] Specifically, the second current collector 30 of the second straight portion 320 and the second current collector 30 of the second corner portion 310 are integrally formed, and the side of the second current collector 30 of the second straight portion 320 facing the first straight portion 110 is coated with a second active material layer 40. That is, for the second straight portion 320 inserted in the accommodating space R, its second active material layer is coated on both sides of the second current collector 30. Since the second straight portion 320 inserted in the accommodating space R needs to participate in the electrochemical reaction inside the battery on both sides, by coating the second current collector 30 of the second straight portion 320 inserted in the accommodating space R with the second active material layer 40, space is fully utilized, the energy density of the battery is improved, and thus the charge and discharge efficiency of the battery is improved. For the second straight portion 320 not inserted in the accommodating space R, its second active material layer is coated on the side of the second current collector 30 facing the first straight portion 110. Since the second straight portion 320, which is not inserted into the accommodating space R, only one side needs to participate in the electrochemical reaction inside the battery, by coating the second straight portion 320, which is not inserted into the accommodating space R, with the second active material layer 40, unnecessary material waste can be avoided while meeting functional requirements, and the overall structure and manufacturing process of the battery can be simplified. In addition, due to the special structure of the second corner portion 310, it is more susceptible to external forces such as compression and bending than the second straight portion 320. If the active material is coated on the second current collector 30 of the second corner portion 310, the active material may fall off or shift when the cell is subjected to these external forces, thereby increasing the risk of short circuit. Therefore, this embodiment effectively reduces the risk of short circuit and ensures the safe and stable operation of the cell by using the second current collector 30 only for the second corner portion 310.

[0060] In some embodiments, the coating length of the first active material layer 20 is greater than the coating length of the second active material layer 40; and / or,

[0061] The coating width of the first active material layer 20 is greater than the coating width of the second active material layer 40.

[0062] Specifically, the coating length of the first active material layer 20 can be greater than the coating length of the second active material layer 40 along the length of the electrode sheet; alternatively, the coating width of the first active material layer 20 can be greater than the coating width of the second active material layer 40 along the width of the electrode sheet; or the coating length of the first active material layer 20 can be greater than the coating length of the second active material layer 40, and simultaneously, the coating width of the first active material layer 20 can be greater than the coating width of the second active material layer 40 along the width of the electrode sheet. The difference in coating length and / or coating width between the first active material layer 20 and the second active material layer 40 can be 1.5 mm to 2 mm. This allows the coating area of ​​the first active material layer 20 to be larger than the coating area of ​​the second active material layer 40.

[0063] Taking the first electrode 100 as the negative electrode and the second electrode 300 as the positive electrode as an example, by making the coating area of ​​the first active material layer 20 larger than the coating area of ​​the second active material layer 40, that is, increasing the coating area of ​​the negative active material, it is ensured that the negative electrode has enough lithium insertion sites, thereby effectively avoiding the precipitation of lithium dendrites on the surface of the negative electrode and improving the safety and cycle life of the battery.

[0064] Optionally, the ratio of negative to positive capacity between the first straight portion 110 with the first tab welded thereto and the adjacent second straight portion 320 in the first electrode 100 is higher than the ratio of negative to positive capacity between the first straight portion 110 without the first tab welded thereto and the adjacent second straight portion 320.

[0065] The so-called negative / positive electrode capacity ratio, also known as the N / P ratio, refers to the ratio of the specific capacity of the negative electrode active material to the specific capacity of the positive electrode active material. Its calculation formula can refer to commonly used formulas in the field, and will not be detailed in this embodiment. During the charging and discharging process of a lithium battery, lithium ions are released from the positive electrode, migrate through the electrolyte to the negative electrode, and embed themselves in the negative electrode material. If the negative electrode does not have enough space to accommodate these lithium ions, they will deposit on the surface of the negative electrode as metallic lithium, resulting in lithium plating.

[0066] Taking the first tab as the negative electrode tab as an example, since the current distribution and lithium ion flow rate are relatively large in the area near the negative electrode tab, if the N / P ratio is too low, the capacity of the negative electrode relative to the positive electrode is insufficient. During charging, not all lithium ions extracted from the positive electrode can be effectively received and embedded by the negative electrode, which easily leads to lithium plating. Based on this, this embodiment sets the negative-to-positive electrode capacity ratio between the first straight portion 110 with the first tab welded to it and the adjacent second straight portion 320 in the first electrode 100 to be higher than the negative-to-positive electrode capacity ratio between the first straight portion 110 without the first tab welded to it and the adjacent second straight portion 320. This increases the effective capacity of the negative electrode in the first tab area. For example, assuming the original N / P ratio is 1.04, it can be increased to 1.06 by replacing the second electrode 300. In this way, during charging, more lithium ions can find a place to be embedded in this negative electrode area with a high N / P ratio, which helps to reduce the risk of lithium plating and thus improves the safety and stability of the battery.

[0067] The ratio of negative to positive capacity between the first straight portion 110 without the first electrode tab and the adjacent second straight portion 320 can be 1.04. The N / P ratio between the first straight portion 110 with the first electrode tab and the adjacent second straight portion 320 in the first electrode 100 is greater than 1.04, for example, it can be 1.06.

[0068] In some embodiments, at least one of the first current collector 10 and the second current collector 30 is a composite current collector. That is, the first current collector 10 can be a composite current collector, or the second current collector 30 can be a composite current collector, or both the first current collector 10 and the second current collector 30 can be composite current collectors, depending on actual needs. As a novel current collector material, the composite current collector has a structure similar to a "sandwich," composed of a polymer material and a metal layer. Specifically, the middle layer of the composite current collector is a base film, typically composed of polymer materials such as polyethylene terephthalate (PET), polypropylene (PP), or polyimide (PI), while the outer two layers are formed by depositing metal (copper or aluminum) using a coating technique to create a conductive layer. This structure allows the composite current collector to maintain high conductivity while also possessing the lightweight, flexibility, and insulation properties of polymer materials, thereby improving battery performance and safety.

[0069] In the battery cell, the first electrode 100 and the second electrode 300 can be respectively welded with tabs to lead out the positive and negative terminals from the battery cell, thereby achieving connection with an external circuit. In some embodiments, the battery cell further includes:

[0070] At least one first electrode lug is welded to the first straight portion 110;

[0071] Multiple second tabs are provided, each of which is welded to the second straight portion 320 of a second electrode 300. The multiple second tabs are stacked and connected along the folding direction of the first electrode 100 and are spaced apart from the first tabs along the width direction of the battery cell.

[0072] Specifically, the first electrode 100 can be welded with a first electrode tab. Since the first electrode 100 has a continuous fan-shaped structure, only one first electrode tab is required. The first electrode tab is welded to a first straight portion 110, which is a single electrode tab structure. The electrode tab can be centrally located. Alternatively, multiple first electrode tabs can be provided, such as two, three, or four. Each first electrode tab is welded to a first straight portion 110, which is a multi-electrode tab structure.

[0073] The second electrode 300 can be welded with second tabs. For multiple second electrode 300s, the same number of second tabs can be configured, with each second tab welded to a second straight portion 320 of a second electrode 300; or, more second tabs than the number of second electrode 300s can be configured, with second tabs welded to both second straight portions 320 of the second electrode 300. Furthermore, the number of second tabs welded to each second straight portion 320 can be one or more, such as two, three, or four, and this embodiment does not impose any restrictions on this.

[0074] When multiple second electrode plates 300 are inserted into the receiving space R of the second electrode plate 300, multiple second electrode tabs overlap accordingly and can be fixed together by welding.

[0075] In some embodiments, the first electrode 100 is a negative electrode, and the second electrode 300 is a positive electrode. Since the first electrode 100 is a negative electrode, graphite can be used as the negative electrode active material during its preparation, and it is mixed uniformly with a binder and a conductive agent in a certain proportion to form a negative electrode slurry. The negative electrode slurry is then coated onto copper foil, and after drying, rolling, and other processes, a negative electrode is formed. The second electrode 300 is a positive electrode, and during its preparation, a ternary material can be used as the positive electrode active material, and it is mixed with a binder and a conductive agent to form a positive electrode slurry. The positive electrode slurry is then coated onto aluminum foil, and after similar drying and rolling processes, a positive electrode is formed.

[0076] The first electrode 100 is a negative electrode, and the second electrode 300 is a positive electrode. That is, the negative electrode is designed as a continuous folding fan structure, while the positive electrode adopts a conventional sheet structure or a U-shaped structure as described in the above embodiment, so as to be inserted into the accommodating space R formed by the negative electrode from either side.

[0077] This utility model also proposes a battery, which includes a casing and a battery cell as described in the foregoing embodiments, with the battery cell disposed within the casing. The specific structure of the battery cell is as described in the foregoing embodiments. Since this battery adopts all the technical solutions of all the foregoing embodiments, it possesses at least all the technical effects brought about by the technical solutions of the foregoing embodiments, and will not be elaborated upon here. The battery may be a lithium battery, including but not limited to this.

[0078] The above description is only a part or preferred embodiment of this utility model. Neither the text nor the drawings should limit the scope of protection of this utility model. All equivalent structural transformations made using the content of this utility model specification and drawings under the overall concept of this utility model, or direct / indirect applications in other related technical fields, are included within the scope of protection of this utility model.

Claims

1. An electric cell, characterized by, Comprising: a first electrode sheet, folded in a fan shape, a plurality of sequentially spaced accommodation spaces being formed along a folding direction of the first electrode sheet, any two adjacent accommodation spaces having openings facing opposite directions; a diaphragm, attached to opposite sides of the first electrode sheet and folded along with the first electrode sheet; a plurality of second electrode sheets, opposite in polarity to the first electrode sheet, each second electrode sheet being inserted into at least one accommodation space of the first electrode sheet.

2. The battery cell according to claim 1, wherein: the first electrode sheet is configured to have a plurality of first flat portions and a plurality of first corner portions, the plurality of first flat portions being sequentially arranged along the folding direction of the first electrode sheet, any two adjacent first flat portions being connected by a first corner portion.

3. The battery cell according to claim 2, wherein: the second electrode sheet is folded in a U shape to be configured to have a second corner portion and two second flat portions, the two second flat portions being connected by the second corner portion; at least one second flat portion of each second electrode sheet is inserted into an accommodation space of the first electrode sheet.

4. The electric cell of claim 3, wherein, the first flat portion and the first corner portion each include a first current collector, the first current collector of the first flat portion being coated with a first active material layer; wherein the first active material layer is coated on opposite sides of the first current collector of each first flat portion.

5. The electric cell of claim 4, wherein, the second flat portion and the second corner portion each include a second current collector; wherein the second current collector of the second flat portion is coated with a second active material layer on a side facing the first flat portion.

6. The electric cell of claim 5, wherein, the first active material layer has a coating length greater than a coating length of the second active material layer; and / or the first active material layer has a coating width greater than a coating width of the second active material layer.

7. The electric cell of claim 5, wherein, at least one of the first current collector and the second current collector is a composite current collector.

8. The electric cell of claim 3, wherein, Further comprising: at least one first tab, welded to the first flat portion; a plurality of second tabs, each second tab being welded to the second flat portion of one second electrode sheet, the plurality of second tabs being connected in a stack along the folding direction of the first electrode sheet and being spaced apart from the first tab along a width direction of the battery cell.

9. The cell of any one of claims 1 to 8, wherein, the first electrode sheet is a negative electrode sheet, and the second electrode sheet is a positive electrode sheet.

10. A battery, characterized by comprising a housing and the battery cell according to any one of claims 1 to 9, the battery cell being arranged in the housing.

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