Battery structure and electric device
By adopting parallel wound cell structure and protective layer design in lithium-ion batteries, the problem of corner lithium-ion is solved, and the cycle performance and safety of the battery are improved, especially the stability under high temperature conditions.
Patent Information
- Application Number
- CN202421852527.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-01
- Publication Date
- 2025-07-04
- Estimated Expiration
- 2034-08-01
AI Technical Summary
There is too much stress at the corners of existing lithium-ion battery coiled soft-pack batteries, resulting in risk of lithium corner analysis and internal short circuit, affecting battery cycle stability and difficulty in achieving large-scale safe charging.
Two and multiple winding battery cells are used to parallel structures. By setting a protective layer at the connection between the electrode ear and the glued electrode ear, corner stress is reduced and parallel connection is achieved, reducing the heat generation of the battery cells and improving the electrolyte infiltration effect.
It effectively improves the lithium cornering phenomenon, improves the cycle performance and safety performance of the battery, especially the stability under high temperature conditions.
Smart Images
Figure CN223066245U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of batteries, and particularly relates to a battery structure and an electrical device. Background Art
[0002] During the long-term room temperature charge and discharge cycle of a wound thick lithium-ion battery cell, due to poor electrolyte infiltration and drying at the corners of the negative electrode tab, and at the same time, the active material layer at the corners is continuously bent and extruded by the winding structure for a long time. After cyclic expansion, delamination and peeling are likely to occur between the active material layer and the negative current collector here, resulting in serious lithium deposition at the negative electrode corners in the later stage of the cycle and obvious cycle attenuation, which seriously affects the long-term cycle stability of the lithium battery.
[0003] It can be seen that in the existing batteries, there are problems of excessive stress at the corners of the thick cells of the wound soft-pack batteries and mismatched CB values caused by the cathode tab covering the anode tab, which easily leads to lithium deposition at the corners of the cell. The subsequent lithium crystal branches will not only further increase the thickness of the cell, but also pose a safety risk of internal short circuit caused by piercing the separator. On the one hand, the problem of lithium deposition at the corners seriously affects the normal development of the entire battery industry. On the other hand, the existing battery structures also have the problem of being difficult to achieve high-rate safe charging, which greatly limits the development of high-energy and high-rate wound cells. Therefore, a new technical solution is urgently needed to solve the above problems. Summary of the Utility Model
[0004] One of the purposes of the utility model is to provide a battery structure aiming at the deficiencies of the prior art, which can improve the problem of lithium deposition at the corners during the cycle.
[0005] To achieve the above purpose, the utility model adopts the following technical solutions:
[0006] A battery structure includes a first wound cell, the first wound cell has a first adhesive tab, at least one second wound cell, the second wound cell has a first tab portion, and at least a part of the first tab portion is adhesively connected to the first adhesive tab. The stacked first wound cell and the second wound cell are connected in parallel with two tabs inside.
[0007] As an improvement of the battery structure of the utility model, the first tab portion and the first adhesive tab are bent together to form a bent area, and the connection between the first tab portion and the first adhesive tab is arranged between the first tab portion and the bent area.
[0008] As an improvement of the battery structure of the utility model, the first pole ear portion facing away from the connection has a first protective layer, the first glue-attached pole ear facing away from the connection has a second protective layer, the first protective layer and the second protective layer are integrally connected, and the first protective layer covers the free end of the first pole ear portion.
[0009] As an improvement of the battery structure of the utility model, the thickness of the first pole ear portion is not greater than the thickness of the metal area of the first pole ear with glue, and the first pole ear portion is welded to the metal area of the first pole ear with glue.
[0010] As an improvement of the battery structure of the utility model, the thickness of the metal area of the first glue-carrying electrode ear is 0.06mm-0.1mm.
[0011] As an improvement of the battery structure of the utility model, the weld mark length of the first pole ear portion is smaller than the width of the first pole ear portion, and the position height of the weld mark edge of the first pole ear portion is smaller than the position height of the free end of the first pole ear portion.
[0012] As an improvement of the battery structure of the utility model, the thickness of the first protective layer and the second protective layer are both 20 μm-60 μm.
[0013] As an improvement of the battery structure of the utility model, the thickness of the first protective layer is less than the thickness of the second protective layer, so as to save the internal space of the battery and improve the energy density of the battery.
[0014] As an improvement of the battery structure of the utility model, the rated capacity of the first wound battery cell is 0.95 to 1.05 times the rated capacity of a single second wound battery cell.
[0015] As an improvement of the battery structure of the utility model, the first wound battery cell and at least one of the second wound battery cells are divided from finished battery cells, and the total heat generation of all the wound battery cells in parallel is 32%-66% of the total heat generation of the finished battery cells.
[0016] As an improvement of the battery structure of the utility model, the first wound battery cell and at least one of the second wound battery cells are divided from finished battery cells, the number of winding layers of a single wound battery cell is ≥2, and the total number of winding layers of all wound battery cells in parallel is equal to the number of winding layers of the finished battery cell.
[0017] As an improvement of the battery structure of the utility model, the first wound battery cell and at least one of the second wound battery cells are formed by dividing a finished battery cell. The cycle retention rate of all the wound battery cells connected in parallel after a preset number of cycles is at least 1.09 times that of the finished battery cell, and the cycle expansion rate of all the wound battery cells connected in parallel after the preset number of cycles is not greater than 0.79 times that of the finished battery cell. The preset number of cycles is not less than 800 weeks.
[0018] The second object of the utility model is to provide an electrical device including the battery structure as described above.
[0019] The beneficial effects of the utility model are as follows: 1) In the utility model, two or more wound bare battery cells are connected in parallel inside. The number of layers of each battery cell connected in parallel can be effectively reduced. Compared with a thick battery cell with the same total number of layers, the number of layers of each bare battery cell connected in parallel is smaller, so that the corner radian is smaller, the stress at the corner is effectively reduced, the electrolyte infiltration effect is better, and it is more beneficial to improve the phenomenon of lithium deposition at the corner during cycling; 2) The two or more bare battery cells connected in parallel in the utility model are parallel-connected battery cells. Based on the parallel shunt, the heat generation of the battery cells connected in parallel is reduced, the internal temperature of the battery cells is more stable, and it is more beneficial to improve the cycling performance of the battery cells, especially the high-temperature performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is a schematic structural diagram of Embodiment 1 of the utility model.
[0021] Figure 2 It is a schematic structural diagram of the welding area of the tab of Embodiment 1 of the utility model.
[0022] Figure 3 It is a schematic structural diagram of two wound battery cells stacked on each other in Embodiment 1 of the utility model.
[0023] Figure 4 It is a schematic structural diagram of the finished battery cell of the utility model.
[0024] Figure 5 It is a schematic diagram of the corner size of Embodiment 1 of the utility model.
[0025] Wherein: 1. The first wound battery cell; 11. The first tab with glue; 11a. The metal area; 11b. The tab glue; 2. The second wound battery cell; 21. The first tab part; 21a. The free end of the first tab part; 3. The bending area; 41. The first protective layer; 42. The second protective layer; 5. The welding mark; 6. The finished battery cell; r. The radius of the outermost arc of the corner of the finished battery cell. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0026] If certain terms are used in the specification and claims to refer to specific components, those skilled in the art should understand that manufacturers may use different names to refer to the same component. The specification and claims do not use the difference in names as a way to distinguish components, but rather use the difference in the functions of the components as the criterion for distinction. As used throughout the specification and claims, "comprising" is an open-ended term and should be interpreted as "comprising but not limited to". "Substantially" means within an acceptable error range, and those skilled in the art can solve technical problems within a certain error range and basically achieve the technical effects.
[0027] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model 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. Therefore, it should not be construed as a limitation to the present utility model.
[0028] In the utility model, unless otherwise clearly specified and defined, terms such as "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.
[0029] The following is a further detailed description of the present utility model in conjunction with the attached Figures 1 to 5 This is not a limitation to the present utility model.
[0030] A battery structure includes a first wound battery cell 1 and at least one second wound battery cell 2. The first wound battery cell 1 has a first adhesive tape tab 11, and the second wound battery cell 2 has a first tab portion 21. At least a part of the first tab portion 21 is adhesively attached to the first adhesive tape tab 11. The stacked first wound battery cell 1 and second wound battery cell 2 are connected in parallel by two tabs inside.
[0031] Preferably, the first tab portion 21 and the first adhesive tape tab 11 are bent together to form a bent area 3, and the connection between the first tab portion 21 and the first adhesive tape tab 11 is arranged between the first tab portion 21 and the bent area 3.
[0032] Preferably, the first tab portion 21 has a first protective layer 41 away from the connection, and the first adhesive tape tab 11 has a second protective layer 42 away from the connection. The first protective layer 41 and the second protective layer 42 are integrally connected, and the first protective layer 41 covers the free end 21a of the first tab portion.
[0033] Preferably, the thickness of the first tab 21 is not greater than the thickness of the metal region 11a of the first tabbed electrode ear 11, and the first tab 21 is welded to the metal region 11a of the first tabbed electrode ear 11.
[0034] Preferably, the rated capacity of the first wound battery cell 1 is 0.95 to 1.05 times the rated capacity of a single second wound battery cell 2.
[0035] Preferably, the first wound battery cell 1 and at least one second wound battery cell 2 are formed by dividing a finished battery cell 6, and the total heat generation of all the wound battery cells connected in parallel is 32%-66% of the total heat generation of the finished battery cell 6.
[0036] Preferably, the first wound battery cell 1 and at least one second wound battery cell 2 are formed by dividing a finished battery cell 6, the number of winding layers of a single wound battery cell ≥ 2, wherein the number of winding layers of a single wound battery cell can be 2 to 15 layers, and the total number of winding layers of all the wound battery cells connected in parallel is equal to the number of winding layers of the finished battery cell 6.
[0037] Preferably, the first wound battery cell 1 and at least one second wound battery cell 2 are formed by dividing a finished battery cell 6, the cycle retention rate of all the wound battery cells connected in parallel at a preset number of cycles is at least 1.09 times the cycle retention rate of the finished battery cell 6, the cycle expansion rate of all the wound battery cells connected in parallel at a preset number of cycles is not greater than 0.79 times the cycle expansion rate of the finished battery cell 6, and the preset number of cycles is not less than 800 weeks.
[0038] Since CB = (anode coating areal density × anode active material content × anode specific capacity) / (cathode coating areal density × cathode active material content × cathode specific capacity), when the corner radian of the internally connected battery cells is smaller, the corner CB value is more sufficient, which is more conducive to improving lithium deposition at the corner.
[0039] Specifically, the preparation method of the battery structure of the present utility model includes the following steps: S1, preparing a first wound battery cell 1 and a second wound battery cell 2 stacked on each other; S2, attaching and connecting the first tab 21 of the second wound battery cell 2 to the first tabbed electrode ear 11 of the first wound battery cell 1;
[0040] S3, enabling the first wound battery cell 1 and the second wound battery cell 2 to be connected in parallel by internal connection of two tabs to form an internally connected battery structure.
[0041] In addition, the present utility model also protects an electrical device having such a battery structure, which can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, and so on. Among them, the vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or an extended-range electric vehicle, etc.; the spacecraft includes an airplane, a rocket, a space shuttle, a spaceship, and so on; the electric toy includes a fixed or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric airplane toy, and so on; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and a railway electric tool, for example, an electric drill, an electric grinding wheel, an electric wrench, an electric screwdriver, a hammer drill, an impact electric drill, a concrete vibrator, a planer, and so on.
[0042] Preferably, the battery structure can be a lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, etc.
[0043] To make the technical solutions and advantages of the present utility model clearer, the present utility model and its beneficial effects will be further described in detail below in conjunction with specific embodiments, but the embodiments of the present utility model are not limited thereto.
[0044] Embodiment 1
[0045] A battery structure, as Figures 1 to 3 shown, includes a first wound cell 1 and a second wound cell 2 with the same rated capacity. The first wound cell 1 has a first gummed tab 11, and the second wound cell 2 has a first tab portion 21. The first tab portion 21 does not have tab gum. A part of the first tab portion 21 is adhesively connected to the metal area 11a of the first gummed tab 11. The stacked first wound cell 1 and second wound cell 2 are connected in parallel by two tabs inside.
[0046] The preparation steps of the battery structure include:
[0047] (1) Preparation of the positive electrode plate
[0048] Lithium cobaltate as the positive electrode material, acetylene black as the conductive agent, and polyvinylidene fluoride (PVDF) as the binder are fully stirred and mixed evenly in an N-methylpyrrolidone solvent system, and then coated on an Al foil. After drying, rolling, and slitting, the positive electrode plate is obtained;
[0049] (2) Preparation of the negative electrode plate
[0050] The negative electrode material, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) were thoroughly stirred and mixed evenly in a deionized water solvent system according to a mass ratio of 98.1:0.5:0.7:0.7, and then coated on a Cu foil. After drying, rolling, and slitting, the negative electrode sheet was obtained;
[0051] (3) Preparation of the separator
[0052] A polyethylene (PE) porous polymer film was used as the separator;
[0053] (4) Preparation of the electrolyte
[0054] Ethylene carbonate (EC): Diethyl carbonate (DEC): Propylene carbonate (PC): Propyl propionate (PP): Vinylene carbonate (VC) = 25:25:15:31:4 were selected to prepare a non-aqueous organic solvent, and a solution prepared by mixing lithium salt LiPF6 and this non-aqueous organic solvent according to a mass ratio of 8:92 was used as the electrolyte of the lithium-ion battery;
[0055] (5) Preparation of the lithium-ion secondary battery
[0056] The positive electrode sheet, separator, and negative electrode sheet were stacked in sequence, with the separator placed in the middle of the positive electrode sheet and the negative electrode sheet to play a role in safety isolation, and then wound to obtain an electrode assembly. Among them, a first wound cell 1 and a second wound cell 2 were wound. The number of winding layers of the first wound cell 1 was 12 layers, and the number of winding layers of the second wound cell 2 was 12 layers. The first wound cell 1 and the second wound cell 2 were stacked in a packaging case, filled with the electrolyte and sealed to obtain the required lithium-ion battery.
[0057] In this embodiment, the two bare cells connected in parallel inside are parallel-connected cells. According to the fact that the DCR of each cell connected in parallel inside will increase by about 30% compared with that of a wound soft-pack cell with the same capacity as this parallel-connected cell. Let the DCR of a wound soft-pack cell be R, then the DCR of each cell connected in parallel inside is 1.3R, and the voltage is all U, and the total current passing through is also all I. Then the heat generation Q1 of a wound soft-pack cell = I 2 RT (T is time, the same below). According to the parallel battery total resistance formula, the total resistance R1 of the cells connected in parallel inside was calculated to be 0.65R. Then the heat generation Q of the cells connected in parallel inside = 0.65I 2 RT = 0.65Q1. Therefore, the heat generation of the cells connected in parallel inside is reduced, the internal temperature of the cells is more stable, and it is more beneficial to improve the cycle performance of the cells.
[0058] In this embodiment, the second wound battery cell 2 is the upper battery cell, and the first wound battery cell 1 is the lower battery cell. The tab of the upper battery cell has no tab glue, and the tab of the lower battery cell is provided with tab glue 11b. The tabs of the upper battery cell and the tabs of the lower battery cell are connected together by welding or other means, and the welding point is located between the folded tabs and the horizontal position where the tab without tab glue is embedded in the electrode plate. It is specified that the height of the exposed end of the tab without tab glue cannot exceed the horizontal position where the tab without tab glue is embedded in the electrode plate, so as to prevent the free end 21a of the first tab part from piercing the electrode plate and the separator. Moreover, the welding sequence of the welding points is not limited. It can be from the side of the tab without tab glue to the side of the other tab, or in the reverse order. Both sides of the welding point are protected with adhesive tape.
[0059] In addition, it is also specified that the length of the weld mark 5 formed by welding two tabs needs to be ≤ the tab width of the first tab part 21 - 2 mm, so as to ensure that the welding strength is within the optimal range.
[0060] Embodiment 2
[0061] Different from Embodiment 1, one first wound battery cell 1 and three identical second wound battery cells 2 are wound. The rated capacity of the first wound battery cell 1 is the same as the rated capacity of each second wound battery cell 2. The winding layer number of the first wound battery cell 1 is 6 layers, and the winding layer number of each second wound battery cell 2 is 6 layers. The first wound battery cell 1 and the three second wound battery cells 2 are stacked in the packaging shell, electrolyte is injected and sealed to obtain the required lithium-ion battery. By having only one bare battery cell with a tab with tab glue and the tabs of the other wound battery cells having no tab glue, it can effectively ensure that there is no liquid leakage in the top sealing of the tab glue. At the same time, compared with a wound bare battery cell with 24 layers of the same number of layers, for a soft-pack battery cell composed of two or more bare battery cells, the smaller the corner arc and the closer it is to a plane, the smaller the stress at the corner, which makes the electrolyte infiltration better and is more conducive to improving the phenomenon of lithium deposition at the corner during cycling.
[0062] Embodiment 3
[0063] Different from Embodiment 1, the winding layer number of one first wound battery cell 1 obtained by winding is 14 layers, and the winding layer number of one second wound battery cell 2 obtained by winding is 15 layers. The rated capacity of the first wound battery cell 1 is 0.98 times the rated capacity of the second wound battery cell 2. The first wound battery cell 1 and the second wound battery cell 2 are stacked in the packaging shell, electrolyte is injected and sealed to obtain the required lithium-ion battery.
[0064] Embodiment 4
[0065] Different from Example 1, one first wound battery cell 1 and two identical second wound battery cells 2 are wound. The rated capacity of the first wound battery cell 1 is the same as that of each second wound battery cell 2. The winding layer number of the first wound battery cell 1 is 8 layers, and the winding layer number of each second wound battery cell 2 is 8 layers. The first wound battery cell 1 and the two second wound battery cells 2 are stacked in a packaging case, electrolyte is injected and sealed to obtain the required lithium-ion battery.
[0066] Example 5
[0067] Different from Example 3, one first wound battery cell 1 and two identical second wound battery cells 2 are wound. The rated capacity of the first wound battery cell 1 is 0.95 times that of the second wound battery cell 2. The winding layer number of the first wound battery cell 1 is 9 layers, and the winding layer number of each second wound battery cell 2 is 10 layers. The first wound battery cell 1 and the two second wound battery cells 2 are stacked in a packaging case, electrolyte is injected and sealed to obtain the required lithium-ion battery.
[0068] Example 6
[0069] Different from Example 3, the winding layer number of one first wound battery cell 1 obtained by winding is 15 layers, and the winding layer number of one second wound battery cell 2 obtained by winding is 14 layers. The rated capacity of the first wound battery cell 1 is 1.05 times that of the second wound battery cell 2. The first wound battery cell 1 and the second wound battery cell 2 are stacked in a packaging case, electrolyte is injected and sealed to obtain the required lithium-ion battery.
[0070] Comparative Example 1
[0071] Different from Example 1, one battery cell with a winding layer number of 24 layers is wound. Among them, the total winding layer number and the battery capacity of the batteries in Example 1, Example 2, Example 4 and Comparative Example 1 are the same, that is, the battery cell in Comparative Example 1 can be regarded as a finished battery cell 6 to be divided and related to Example 1, Example 2 and Example 4 respectively.
[0072] Comparative Example 2
[0073] Different from Example 3, one battery cell with a winding layer number of 29 layers is wound. Among them, the total winding layer number and the battery capacity of the batteries in Example 3, Example 5, Example 6 and Comparative Example 2 are the same, that is, the battery cell in Comparative Example 2 can be regarded as a finished battery cell 6 to be divided and related to Example 3, Example 5 and Example 6 respectively.
[0074] The following results are obtained by comparing Examples 1 to 6 with Comparative Examples 1 to 2.
[0075]
[0076] Table 1
[0077] According to the results in Table 1 above and in combination with Figure 4 it can be seen that at the two corners on both sides of the wound soft-pack battery cell, as the number of layers increases, the radian becomes larger, which will cause the CB value closer to the outer layer to be smaller, and lithium deposition is more likely to occur at the corners; according to the above results and in combination with Figure 5 it can be seen that when the capacity is the same as that of a single soft-pack battery cell, the number of layers of each internally-paralleled battery cell is half of that of a single soft-pack battery cell (for example: if a single soft-pack battery cell is designed with 24 layers, the number of layers of each internally-paralleled battery cell is 12 layers), which can effectively reduce the size of the outermost arc radius at the corners, so that lithium deposition is less likely to occur in the battery cell. Compared with a single wound soft-pack battery cell with the same capacity and the same number of layers, the smaller the number of layers of two or more internally-paralleled battery cells, the smaller the corner radian of the battery cell, the closer the corner radian is to a plane, the better the electrolyte infiltration, and the more obvious the improvement of lithium deposition at the corners.
[0078] Obviously, the present utility model internally-parallels two or more wound bare battery cells into a soft-pack battery through a new tab splicing method, thereby improving the problem of lithium deposition at the corners of the wound soft-pack battery, and at the same time improving the cycle performance, interface stability and safety performance of the battery.
[0079] According to the disclosure and teachings of the above specification, those skilled in the art to which the present utility model pertains can also make changes and modifications to the above embodiments. Therefore, the present utility model is not limited to the above specific embodiments, and any obvious improvements, substitutions or variations made by those skilled in the art on the basis of the present utility model all fall within the protection scope of the present utility model. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present utility model.
Claims
1. A battery structure, characterized in that, include: A first wound battery cell (1) having a first electrode tab (11) with glue; At least one second wound battery core (2) having a first pole lug portion (21); At least a portion of the first pole lug portion (21) is bonded and connected to the first adhesive-coated pole lug (11); The first wound battery core (1) and the second wound battery core (2) stacked on each other are placed in two pole ears and connected in parallel.
2. The battery structure according to claim 1, wherein: The first pole ear portion (21) and the first adhesive pole ear (11) are bent together to form a bending zone (3), and the connection between the first pole ear portion (21) and the first adhesive pole ear (11) is arranged between the first pole ear portion (21) and the bending zone (3).
3. The battery structure according to claim 2, characterized in that: The first pole ear portion (21) is provided with a first protective layer (41) away from the connection, and the first rubber-coated pole ear (11) is provided with a second protective layer (42) away from the connection. The first protective layer (41) and the second protective layer (42) are integrally connected, and the first protective layer (41) covers the free end of the first pole ear portion.
4. The battery structure according to any one of claims 1 to 3, characterized in that: The thickness of the first pole lug portion (21) is not greater than the thickness of the metal area (11a) of the first pole lug with glue (11), and the first pole lug portion (21) is welded to the metal area (11a) of the first pole lug with glue (11).
5. The battery structure according to any one of claims 1 to 3, characterized in that: The rated capacity of the first wound battery cell (1) is 0.95 to 1.05 times the rated capacity of a single second wound battery cell (2).
6. The battery structure according to any one of claims 1 to 3, characterized in that: The first wound battery cell (1) and at least one of the second wound battery cells (2) are divided from finished battery cells, and the total heat generation of all the wound battery cells connected in parallel is 32%-66% of the total heat generation of the finished battery cells.
7. The battery structure according to any one of claims 1 to 3, characterized in that: The first wound battery cell (1) and at least one of the second wound battery cells (2) are divided from finished battery cells, the number of winding layers of a single wound battery cell is ≥2, and the total number of winding layers of all wound battery cells connected in parallel is equal to the number of winding layers of the finished battery cell.
8. The battery structure according to any one of claims 1 to 3, characterized in that: The first wound battery cell (1) and at least one of the second wound battery cells (2) are divided from finished battery cells, and the cycle retention rate of all the wound battery cells connected in parallel at a preset number of cycles is at least 1.09 times the cycle retention rate of the finished battery cell, and the preset number of cycles is not less than 800 cycles.
9. The battery structure according to any one of claims 1 to 3, characterized in that: The first wound battery cell (1) and at least one of the second wound battery cells (2) are divided from finished battery cells, and the cycle expansion rate of all the wound battery cells connected in parallel at a preset number of cycles is not greater than 0.79 times the cycle expansion rate of the finished battery cell, and the preset number of cycles is not less than 800 cycles.
10. An electrical device, characterized in that: The invention comprises a battery structure as claimed in any one of claims 1 to 9.