Battery cell and electric device

Abstract

A battery cell and an electric device. The battery cell comprises a casing (100) and a composite electrode sheet (200), and the composite electrode sheet is accommodated in the casing, and comprises a separator (210), a positive electrode active material film (220) and a negative electrode active material film (230). The composite electrode sheet has a multi-layer continuous folding structure, and comprises a plurality of folding portions (201), first connecting portions (202) and second connecting portions (203), wherein the plurality of folding portions are stacked in a first direction, and the first connecting portions and the second connecting portions are respectively located at both ends of the folding portions in a second direction. The positive electrode active material film and / or the negative electrode active material film are / is electrically connected to the casing. The second direction is a thickness direction of the battery cell, and the first direction is perpendicular to the second direction. The space occupied by a positive electrode current collector and a negative electrode current collector can be saved, so that the volume proportions of the positive electrode active material film and the negative electrode active material film in the battery cell are greater, thereby enabling the energy density of the battery cell to be greater. The transport path of electrons in the second direction can be shorter, which is beneficial to improving the rate performance of the battery cell.

Description

Battery cells and electrical equipment Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a battery cell and an electrical device. Background Technology

[0002] With the rapid development of electronic information technology, various electronic devices are also developing towards intelligence and multi-functionality, which places increasingly higher demands on the energy density of batteries.

[0003] Currently, the current collector accounts for a large proportion of the volume in the battery electrode, resulting in a smaller proportion of the active material in the electrode, which affects the energy density of the battery. Summary of the Invention

[0004] This application provides a battery cell and an electrical device that can improve the energy density of the battery cell.

[0005] In a first aspect, this application provides a battery cell, comprising a casing and a composite electrode sheet housed within the casing. The composite electrode sheet includes a separator, a positive active material membrane, and a negative active material membrane, with the positive and negative active material membranes respectively disposed on opposite sides of the separator. The composite electrode sheet has a multi-layered continuously folded structure, including multiple folded portions, a first connecting portion, and a second connecting portion. The multiple folded portions are stacked along a first direction, and the first and second connecting portions are respectively located at opposite ends of the folded portions along a second direction. The first connecting portion connects to one end of two adjacent folded portions, and the second connecting portion connects to the other end of two adjacent folded portions. The positive and / or negative active material membranes are electrically connected to the casing. The second direction is the thickness direction of the battery cell, and the first and second directions are perpendicular.

[0006] In the above technical solution, by making the composite electrode sheet include a separator, a positive electrode active material film, and a negative electrode active material film, with the positive and negative electrode active material films respectively disposed on both sides of the separator, the space occupied by the positive and negative electrode current collectors can be eliminated, resulting in a larger volume ratio of the positive and negative electrode active material films in the battery cell, thereby increasing the energy density of the battery cell. By making the composite electrode sheet have a multi-layer continuous folded structure, the composite electrode sheet includes multiple folded portions, a first connecting portion, and a second connecting portion. The multiple folded portions are stacked along a first direction, and the first and second connecting portions are respectively located at both ends of the folded portions along a second direction. The first connecting portion connects one end of two adjacent folded portions, and the second connecting portion connects the other end of two adjacent folded portions, which facilitates the housing of the composite electrode sheet within the outer casing. Since the farthest electron transport path within the positive and / or negative electrode active material films is from the side closest to the separator outwards, by electrically connecting the positive and / or negative electrode active material films to the outer casing, the farthest electron transport path within the positive and / or negative electrode active material films is along a second direction. Relative to the length or width direction of the cell, this application sets the second direction as the thickness direction of the cell. This allows the cell to be smaller in the second direction, meaning the electron transport path in the second direction is shorter, which helps reduce the internal resistance of the cell and thus improves the rate performance of the cell.

[0007] In some embodiments of this application, the battery cell further includes a first electrode terminal, which is disposed on the outer casing and insulated from the outer casing. A positive electrode active material membrane is electrically connected to the first electrode terminal, and a negative electrode active material membrane is electrically connected to the outer casing.

[0008] In the above technical solution, by electrically connecting the positive electrode active material membrane to the first electrode terminal and the negative electrode active material membrane to the outer casing, the load can be electrically connected to the positive electrode active material membrane through the first electrode terminal and to the negative electrode active material membrane through the outer casing, thereby enabling the charging and discharging of the battery cell.

[0009] In some embodiments of this application, at the first connection portion, the positive electrode active material film is located between the negative electrode active material film and the outer shell. At the second connection portion, the negative electrode active material film is located between the positive electrode active material film and the outer shell. The battery cell also includes a positive electrode current collector, which is disposed within the outer shell and located on one side of the composite electrode along the second direction, and contacts the positive electrode active material films of the plurality of first connection portions. The first electrode terminal is electrically connected to the positive electrode current collector. The negative electrode active material film at the second connection portion contacts the outer shell.

[0010] In the above technical solution, by placing the positive electrode active material membrane between the negative electrode active material membrane and the outer shell at the first connection portion, and placing the positive electrode current collector inside the outer shell, the positive electrode current collector is located on one side of the composite electrode along the second direction and is in contact with the positive electrode active material membranes of the multiple first connection portions. This allows for a larger contact area between the positive electrode current collector and the positive electrode active material membrane, a larger flow area between the positive electrode current collector and the positive electrode active material membrane, and more stable electron transport between the positive electrode current collector and the positive electrode active material membrane. Furthermore, due to the good conductivity of the positive electrode current collector, by placing the positive electrode current collector and electrically connecting the first electrode terminal to the positive electrode current collector, the electron transport speed between the first electrode terminal and the positive electrode active material membrane is faster, and the stability of electron transport is better. By positioning the negative electrode active material membrane between the positive electrode active material membrane and the outer shell at the second connection, and ensuring that the negative electrode active material membrane at the second connection is in contact with the outer shell, the contact area between the outer shell and the negative electrode active material membrane is increased, the overcurrent area between the outer shell and the negative electrode active material membrane is increased, and the electron transport between the outer shell and the negative electrode active material membrane is more stable.

[0011] In some embodiments of this application, the housing includes a first wall, and along a second direction, a positive current collector is located between the first wall and the composite electrode. Along the second direction, a first insulating layer is disposed between the positive current collector and the first wall.

[0012] In the above technical solution, by placing the positive current collector between the first wall and the composite electrode sheet along the second direction, and providing a first insulating layer between the positive current collector and the first wall along the second direction, the first insulating layer can play an insulating role between the positive current collector and the outer casing, reducing the possibility of short circuit between the positive current collector and the outer casing, and improving the safety of the battery cell.

[0013] In some embodiments of this application, the battery cell further includes a second electrode terminal, which is disposed on the outer casing and insulated from the outer casing. A negative electrode active material membrane is electrically connected to the second electrode terminal, and a positive electrode active material membrane is electrically connected to the outer casing.

[0014] In the above technical solution, by electrically connecting the negative electrode active material membrane to the second electrode terminal and the positive electrode active material membrane to the outer shell, the load can be electrically connected to the negative electrode active material membrane through the second electrode terminal and to the positive electrode active material membrane through the outer shell, thereby enabling the charging and discharging of the battery cell.

[0015] In some embodiments of this application, at the first connection portion, the positive electrode active material membrane is located between the negative electrode active material membrane and the outer casing. At the second connection portion, the negative electrode active material membrane is located between the positive electrode active material membrane and the outer casing. The battery cell also includes a negative electrode current collector, which is disposed within the outer casing, located on one side of the composite electrode along the second direction, and in contact with the negative electrode active material membranes of the plurality of second connection portions. The second electrode terminal is electrically connected to the negative electrode current collector. The positive electrode active material membrane at the first connection portion is in contact with the outer casing.

[0016] In the above technical solution, by placing the negative electrode active material membrane between the positive electrode active material membrane and the outer shell at the second connection portion, and placing the negative electrode current collector inside the outer shell, the negative electrode current collector is located on one side of the composite electrode along the second direction and is in contact with the negative electrode active material membranes of multiple second connection portions. This allows for a larger contact area between the negative electrode current collector and the negative electrode active material membrane, a larger flow area between the negative electrode current collector and the negative electrode active material membrane, and more stable electron transport between the negative electrode current collector and the negative electrode active material membrane. Furthermore, due to the good conductivity of the negative electrode current collector, by placing the negative electrode current collector and electrically connecting the second electrode terminal to the negative electrode current collector, the electron transport speed between the second electrode terminal and the negative electrode active material membrane is faster, and the stability of electron transport is better. By positioning the positive electrode active material membrane between the negative electrode active material membrane and the outer shell at the first connection point, and ensuring that the positive electrode active material membrane at the first connection point is in contact with the outer shell, the contact area between the outer shell and the positive electrode active material membrane is larger, the current flow area between the outer shell and the positive electrode active material membrane is larger, and the electron transport between the outer shell and the positive electrode active material membrane is more stable.

[0017] In some embodiments of this application, the housing includes a second wall, and along a second direction, a negative electrode current collector is located between the second wall and the composite electrode. Along the second direction, a second insulating layer is disposed between the negative electrode current collector and the second wall.

[0018] In the above technical solution, by placing the negative current collector between the second wall and the composite electrode along the second direction, and providing a second insulating layer between the negative current collector and the second wall along the second direction, the second insulating layer can play an insulating role between the negative current collector and the outer casing, reducing the possibility of short circuit between the negative current collector and the outer casing, and improving the safety of the battery cell.

[0019] In some embodiments of this application, the outer casing includes a first casing and a second casing, which are insulated from each other. A positive electrode active material membrane is electrically connected to the first casing, and a negative electrode active material membrane is electrically connected to the second casing.

[0020] In the above technical solution, by making the first shell and the second shell insulated from each other, the positive active material membrane is electrically connected to the first shell, and the negative active material membrane is electrically connected to the second shell, so that the load can be electrically connected to the positive active material membrane through the first shell and to the negative active material membrane through the second shell, thereby enabling the charging and discharging of the battery cell.

[0021] In some embodiments of this application, at the first connection portion, the positive electrode active material membrane is located between the negative electrode active material membrane and the first housing. At the second connection portion, the negative electrode active material membrane is located between the positive electrode active material membrane and the second housing. The positive electrode active material membrane at the first connection portion is in contact with the first housing. The negative electrode active material membrane at the second connection portion is in contact with the second housing.

[0022] In the above technical solution, by positioning the positive electrode active material membrane between the negative electrode active material membrane and the first housing at the first connection portion, and ensuring that the positive electrode active material membrane at the first connection portion is in contact with the first housing, the contact area between the first housing and the positive electrode active material membrane is larger, the current flow area between the first housing and the positive electrode active material membrane is larger, and the electron transport between the first housing and the positive electrode active material membrane is more stable. Furthermore, by positioning the negative electrode active material membrane between the positive electrode active material membrane and the second housing at the second connection portion, and ensuring that the negative electrode active material membrane at the second connection portion is in contact with the second housing, the contact area between the second housing and the negative electrode active material membrane is larger, the current flow area between the second housing and the negative electrode active material membrane is larger, and the electron transport between the second housing and the negative electrode active material membrane is more stable. Moreover, by directly connecting to the housing, the need for a current collector can be eliminated, thereby increasing the energy density of the battery cell.

[0023] In some embodiments of this application, the height of the composite electrode along the second direction is H1, which satisfies 2mm≤H1≤10mm.

[0024] In the above technical solution, when H1 is greater than or equal to 2mm, it facilitates the folding and forming of composite electrodes, reducing the difficulty of cell fabrication. When H1 is less than or equal to 10mm, the electrons inside the cell can travel along the second direction with a shorter path, resulting in lower internal resistance, which is beneficial for improving the rate performance of the cell and also allows for a smaller cell thickness, making it suitable for various electrical devices. Therefore, when 2mm≤H1≤10mm, it not only facilitates the folding and forming of composite electrodes, reducing the difficulty of cell fabrication, but also allows for a shorter path, lower internal resistance, and improved rate performance, while also allowing for a smaller cell thickness, making it suitable for various electrical devices.

[0025] In some embodiments of this application, the composite electrode further includes a positive conductive layer, which is disposed on the side of the positive active material membrane facing away from the separator.

[0026] In the above technical solution, by setting a positive conductive layer and placing it on the side of the positive active material film facing away from the separator, electrons can be transported in the positive active material film along a first direction. In the first direction, electrons only need to pass through a single layer of the positive active material film. Compared with the positive active material film being electrically connected to the outside through the first connection part, i.e., electrons are transported in the positive active material film along a second direction, this solution can shorten the electron transport path in the positive active material film, improve the problem of low conductivity of the positive active material film, reduce the internal resistance of the cell, and help improve the rate performance of the cell.

[0027] In some embodiments of this application, the thickness of the positive electrode conductive layer is H2, which satisfies 0.5μm≤H2≤2μm.

[0028] In the above technical solution, when H2 is greater than or equal to 0.5μm, the current-carrying area of ​​the positive electrode conductive layer is larger, the conductivity is better, which is conducive to improving the speed of electron transmission through the positive electrode conductive layer and making the electron transmission more stable. When H2 is less than or equal to 2μm, the space occupied by the positive electrode conductive layer is smaller, which is conducive to improving the energy density of the cell. Therefore, when 0.5μm≤H2≤2μm, the conductivity of the positive electrode conductive layer is better, which is conducive to improving the speed of electron transmission through the positive electrode conductive layer and making the electron transmission more stable, and the space occupied by the positive electrode conductive layer is smaller, which is conducive to improving the energy density of the cell.

[0029] In some embodiments of this application, the material of the positive electrode conductive layer includes conductive metal and / or conductive carbon.

[0030] In the above technical solution, by making the material of the positive electrode conductive layer include conductive metal and / or conductive carbon, the conductivity of the positive electrode conductive layer can be improved, which is beneficial to increasing the speed of electron transmission through the positive electrode conductive layer and making the electron transmission more stable.

[0031] In some embodiments of this application, the resistivity of the thickness of the positive electrode active material film along the second direction is ρ, which satisfies 0.1Ω·cm≤ρ≤10Ω·cm.

[0032] In the above technical solution, when ρ is greater than or equal to 0.1 Ω·cm, it facilitates the preparation of the positive electrode active material film; when ρ is less than or equal to 10 Ω·cm, it enables the positive electrode active material film to have better conductivity, which is beneficial to increasing the speed of electron transport through the positive electrode active material film and making the electron transport more stable; therefore, when 0.1 Ω·cm ≤ ρ ≤ 10 Ω·cm, it not only facilitates the preparation of the positive electrode active material film, but also enables the positive electrode active material film to have better conductivity, which is beneficial to increasing the speed of electron transport through the positive electrode active material film and making the electron transport more stable.

[0033] In some embodiments of this application, the positive electrode active material film includes a conductive agent, the content of which is Q, satisfying 0.5% ≤ Q ≤ 5.0%.

[0034] In the above technical solution, when Q is greater than or equal to 0.5%, the conductivity of the positive electrode active material film is better, which is conducive to increasing the speed of electron transmission through the positive electrode conductive layer and making the electron transmission more stable. When Q is less than or equal to 5.0%, the proportion of other materials in the positive electrode active material film used to realize metal ion insertion and extraction is higher, which is conducive to improving the energy density of the cell. Therefore, when 0.5% ≤ Q ≤ 5.0%, the conductivity of the positive electrode active material film is better, which is conducive to increasing the speed of electron transmission through the positive electrode conductive layer and making the electron transmission more stable, and it is also conducive to improving the energy density of the cell.

[0035] Secondly, this application provides an electrical device including a battery cell as described above, the battery cell being used to provide electrical energy.

[0036] In some embodiments of this application, the battery cell further includes a first electrode terminal and a positive current collector. The first electrode terminal is disposed within the housing and is insulated from and connected to the housing. The positive current collector is disposed inside the housing, located on one side of the composite electrode sheet along the second direction, and in contact with the positive active material membrane. The first electrode terminal is electrically connected to the positive current collector. The negative active material membrane is in contact with the housing. The electrical device includes a load, which is connected to the first electrode terminal and the housing.

[0037] In the above technical solution, by setting a first electrode terminal and a positive current collector, and making the first electrode terminal disposed on the outer shell and insulated from the outer shell, the positive current collector is disposed inside the outer shell, the positive current collector is located on one side of the composite electrode along the second direction and is in contact with the positive active material membrane, the first electrode terminal is electrically connected to the positive current collector, the negative active material membrane is in contact with the outer shell, and the load is connected to the first electrode terminal and the outer shell, so that the load can be electrically connected to the positive active material membrane through the first electrode terminal and the positive current collector, and electrically connected to the negative active material membrane through the outer shell, thereby enabling the charging and discharging of the battery cell. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings.

[0039] Figure 1 is a three-dimensional structural diagram of a battery cell provided in some embodiments of this application;

[0040] Figure 2 is a cross-sectional structural diagram of a battery cell provided in some embodiments of this application;

[0041] Figure 3 is a schematic diagram of the structure of the composite electrode sheet of the battery cell provided in some embodiments of this application after unfolding;

[0042] Figure 4 is a cross-sectional structural schematic diagram of a battery cell provided in some other embodiments of this application;

[0043] Figure 5 is a cross-sectional structural schematic diagram of a battery cell provided in some other embodiments of this application;

[0044] Figure 6 is a cross-sectional structural schematic diagram of a battery cell provided in some other embodiments of this application;

[0045] Figure 7 is a cross-sectional structural schematic diagram of a battery cell provided in some other embodiments of this application;

[0046] Figure 8 is a schematic diagram of the structure of the composite electrode sheet of the battery cell provided in some other embodiments of this application after unfolding;

[0047] Figure 9 is a schematic diagram of the resistivity test of the positive electrode active material film in the battery cell along the second direction provided in some embodiments of this application.

[0048] Icons: 10-cell; 100-casing; 101-first wall; 102-second wall; 103-side wall; 110-first housing; 120-second housing; 200-composite electrode; 201-folded portion; 202-first connecting portion; 203-second connecting portion; 210-diaphragm; 220-positive electrode active material membrane; 230-negative electrode active material membrane; 240-positive electrode conductive layer; 310-first electrode terminal; 320-second electrode terminal; 410-positive electrode current collector; 420-negative electrode current collector; 510-first insulating layer; 520-second insulating layer; X-first direction; Y-second direction. Specific embodiments.

[0049] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0050] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having" and any variations thereof in the specification, claims and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0051] The terms "first," "second," etc., in the specification, claims, or the accompanying drawings of this application are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0052] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0053] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0054] With the development of the new energy industry, batteries are gradually moving towards higher energy density and higher power density. Batteries primarily rely on the insertion and extraction of metal positive ions between the positive and negative electrode active materials to achieve charging and discharging, and on the electrical connection between the positive and negative current collectors and the load to facilitate electron transfer. Therefore, the higher the volume ratio of active materials in a battery, the higher its energy density. However, currently, the current collector accounts for a relatively large volume ratio in battery electrodes, which affects the volume ratio of active materials in the electrodes, thus impacting the battery's energy density.

[0055] To improve the energy density of a battery cell, this application provides a battery cell comprising a casing and a composite electrode. The composite electrode is housed within the casing and includes a separator, a positive active material membrane, and a negative active material membrane, which are respectively disposed on opposite sides of the separator. The composite electrode has a multi-layered, continuously folded structure, including multiple folded portions, a first connecting portion, and a second connecting portion. The multiple folded portions are stacked along a first direction. The first and second connecting portions are located at opposite ends of the folded portions along a second direction. The first connecting portion connects to one end of two adjacent folded portions, and the second connecting portion connects to the other end of two adjacent folded portions. The positive and / or negative active material membranes are electrically connected to the casing. The second direction is the thickness direction of the battery cell, and the first and second directions are perpendicular.

[0056] In this type of battery cell, by making the composite electrode include a separator, a positive electrode active material film, and a negative electrode active material film, with the positive and negative electrode active material films respectively disposed on both sides of the separator, the space occupied by the positive and negative electrode current collectors can be eliminated, resulting in a larger volume ratio of the positive and negative electrode active material films in the battery cell, thereby increasing the energy density of the battery cell. By making the composite electrode have a multi-layer continuous folded structure, the composite electrode includes multiple folded portions, a first connecting portion, and a second connecting portion. The multiple folded portions are stacked along a first direction, and the first and second connecting portions are respectively located at the two ends of the folded portions along a second direction. The first connecting portion connects one end of two adjacent folded portions, and the second connecting portion connects the other end of two adjacent folded portions, which facilitates the housing of the composite electrode within the outer casing. Since the farthest electron transport path within the positive and / or negative electrode active material films is from the side closest to the separator outwards, by electrically connecting the positive and / or negative electrode active material films to the outer casing, the farthest electron transport path within the positive and / or negative electrode active material films is along a second direction. Relative to the length or width direction of the cell, this application sets the second direction as the thickness direction of the cell. This allows the cell to be smaller in the second direction, meaning the electron transport path in the second direction is shorter, which helps reduce the internal resistance of the cell and thus improves the rate performance of the cell.

[0057] The battery cell provided in this application embodiment can be a secondary battery or a primary battery, such as a lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, etc., and this application embodiment is not limited in this respect. The battery cell can be flat, cuboid, or other shapes, etc., and this application embodiment is not limited in this respect either.

[0058] This application provides an electrical device that uses battery cells as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc.

[0059] Referring to Figures 1 to 3, Figure 1 is a three-dimensional structural diagram of a battery cell provided in some embodiments of this application; Figure 2 is a cross-sectional structural diagram of a battery cell provided in some embodiments of this application; and Figure 3 is a structural diagram of the battery cell after the composite electrode sheet is unfolded in some embodiments of this application.

[0060] This application provides a battery cell 10, which includes a housing 100 and a composite electrode 200. The composite electrode 200 is housed in the housing 100 and includes a separator 210, a positive active material membrane 220 and a negative active material membrane 230. The positive active material membrane 220 and the negative active material membrane 230 are respectively disposed on both sides of the separator 210.

[0061] Wherein, the positive electrode active material membrane 220 refers to a membrane that includes positive electrode active material and is capable of self-supporting, and does not include a positive electrode current collector. The negative electrode active material membrane 230 refers to a membrane that includes negative electrode active material and is capable of self-supporting, and does not include a negative electrode current collector.

[0062] By making the composite electrode 200 include a separator 210, a positive electrode active material membrane 220, and a negative electrode active material membrane 230, with the positive electrode active material membrane 220 and the negative electrode active material membrane 230 respectively disposed on both sides of the separator 210, the space occupied by the positive electrode current collector 410 and the negative electrode current collector 420 can be saved, so that the volume ratio of the positive electrode active material membrane 220 and the negative electrode active material membrane 230 in the battery cell 10 is larger, thereby making the energy density of the battery cell 10 higher.

[0063] In some embodiments, the composite electrode 200 has a multi-layered continuous folded structure, including multiple folded portions 201, a first connecting portion 202, and a second connecting portion 203. The multiple folded portions 201 are stacked along a first direction X. The first connecting portion 202 and the second connecting portion 203 are respectively located at both ends of the folded portions 201 along a second direction Y. The first connecting portion 202 connects one end of two adjacent folded portions 201, and the second connecting portion 203 connects the other end of two adjacent folded portions 201. Along the first direction X, the tail of the first folded portion 201 is connected to the head of the second folded portion 201 through the second connecting portion 203, the tail of the second folded portion 201 is connected to the head of the third folded portion 201 through the first connecting portion 202, and so on.

[0064] By making the composite electrode 200 have a multi-layer continuous folded structure, the composite electrode 200 includes multiple folded portions 201, a first connecting portion 202 and a second connecting portion 203. The multiple folded portions 201 are stacked along the first direction X. The first connecting portion 202 and the second connecting portion 203 are respectively located at both ends of the folded portions 201 along the second direction Y. The first connecting portion 202 connects one end of two adjacent folded portions 201, and the second connecting portion 203 connects the other end of two adjacent folded portions 201, so as to facilitate the inclusion of the composite electrode 200 in the outer shell 100.

[0065] In some embodiments, the positive electrode active material membrane 220 and / or the negative electrode active material membrane 230 are electrically connected to the housing 100. The second direction Y is the thickness direction of the cell 10, and the first direction X is perpendicular to the second direction Y.

[0066] Since the furthest electron transport path within the positive electrode active material membrane 220 and / or the negative electrode active material membrane 230 is from the side closest to the separator 210 outwards, by electrically connecting the positive electrode active material membrane 220 and / or the negative electrode active material membrane 230 to the outer casing 100, the furthest electron transport path within the positive electrode active material membrane 220 and / or the negative electrode active material membrane 230 is along the second direction Y. Since the second direction Y is the length or width direction of the battery cell, this application sets the second direction Y as the thickness direction of the battery cell. This allows the battery cell 10 to be smaller in the second direction Y, meaning the electron transport path in the second direction Y is shorter. This helps reduce the internal resistance of the battery cell 10, thereby improving the rate performance of the battery cell 10.

[0067] In some embodiments, the housing 100 can be made of a high-strength material, such as steel, aluminum alloy or other metal materials, so that the housing 100 has high stress resistance, and thus the housing 100 is not easily deformed or damaged due to stress or environmental changes, thereby making the battery cell 10 more reliable.

[0068] In other embodiments, the outer shell 100 may also be a high-strength non-metallic material such as carbon fiber or rigid plastic, and conductive particles may be added therein to enable electrical connection with the positive electrode active material membrane 220 and / or the negative electrode active material membrane 230.

[0069] In some embodiments, the battery cell 10 is arranged in a cuboid shape with rounded corners, which can better fit the rounded battery compartment in the electrical device.

[0070] In other embodiments, the apex of the battery cell 10 may also be square.

[0071] In some embodiments, the battery cell 10 includes a housing 100, a composite electrode 200, and an electrolyte. The housing 100 is used to contain the composite electrode 200 and the electrolyte. The battery cell 10 mainly operates by the movement of metal ions between the positive electrode active material membrane 220 and the negative electrode active material membrane 230. Taking a lithium-ion battery cell 10 as an example, the positive electrode active material membrane 220 can be lithium cobalt oxide, lithium iron phosphate, ternary materials, or lithium manganese oxide, etc. The negative electrode active material membrane 230 can be carbon materials or silicon materials, etc. The separator 210 can be made of polypropylene (PP) or polyethylene (PE), etc. The electrolyte can include organic solvents, lithium electrolyte salts, etc.

[0072] In some embodiments, the battery cell 10 further includes a first electrode terminal 310, which is disposed on the housing 100 and is insulated from the housing 100. The positive electrode active material membrane 220 is electrically connected to the first electrode terminal 310, and the negative electrode active material membrane 230 is electrically connected to the housing 100.

[0073] By electrically connecting the positive electrode active material membrane 220 to the first electrode terminal 310 and the negative electrode active material membrane 230 to the outer casing 100, the load can be electrically connected to the positive electrode active material membrane 220 through the first electrode terminal 310 and to the negative electrode active material membrane 230 through the outer casing 100, thereby enabling the charging and discharging of the battery cell 10.

[0074] In some embodiments, at the first connection portion 202, the positive electrode active material membrane 220 is located between the negative electrode active material membrane 230 and the outer casing 100. At the second connection portion 203, the negative electrode active material membrane 230 is located between the positive electrode active material membrane 220 and the outer casing 100. The battery cell 10 also includes a positive electrode current collector 410, which is disposed within the outer casing 100. The positive electrode current collector 410 is located on one side of the composite electrode 200 along the second direction Y and is in contact with the positive electrode active material membranes 220 of the plurality of first connection portions 202. The first electrode terminal 310 is electrically connected to the positive electrode current collector 410. The negative electrode active material membrane 230 of the second connection portion 203 is in contact with the outer casing 100.

[0075] By positioning the positive electrode active material membrane 220 between the negative electrode active material membrane 230 and the outer casing 100 at the first connection portion 202, and placing the positive electrode current collector 410 inside the outer casing 100, the positive electrode current collector 410 is located on one side of the composite electrode 200 along the second direction Y and is in contact with the positive electrode active material membranes 220 at the multiple first connection portions 202. This results in a larger contact area between the positive electrode current collector 410 and the positive electrode active material membrane 220, a larger flow area between them, and more stable electron transport. Furthermore, due to the good conductivity of the positive electrode current collector 410, by placing the positive electrode current collector 410 and electrically connecting the first electrode terminal 310 to it, the electron transport speed between the first electrode terminal 310 and the positive electrode active material membrane 220 is faster, and the stability of electron transport is better. By positioning the positive current collector 410 on one side of the composite electrode 200 along the second direction Y, the farthest electron transport path within the positive active material film 220 is along the second direction Y, which is the thickness direction of the cell. Compared to placing the positive current collector 410 on one side of the composite electrode 200 along the first direction X or the third direction Z, this application can shorten the electron transport path, which is beneficial to reducing the internal resistance of the cell 10 and thus improving the rate performance of the cell 10.

[0076] By positioning the negative electrode active material membrane 230 between the positive electrode active material membrane 220 and the outer casing 100 at the second connection portion 203, and ensuring that the negative electrode active material membrane 230 at the second connection portion 203 is in contact with the outer casing 100, the contact area between the outer casing 100 and the negative electrode active material membrane 230 is larger, the overcurrent area between the outer casing 100 and the negative electrode active material membrane 230 is larger, and the electron transport between the outer casing 100 and the negative electrode active material membrane 230 is more stable.

[0077] Taking lithium-ion cell 10 as an example, the positive electrode current collector 410 can be made of aluminum.

[0078] In some embodiments, the thickness of the positive current collector 410 is 5 μm-80 μm. For example, the thickness of the positive current collector 410 can be 5 μm, 40 μm, or 80 μm, etc.

[0079] When the thickness of the positive current collector 410 is greater than or equal to 5 μm, the current-carrying area of ​​the positive current collector 410 is larger, and the conductivity is better, which is conducive to improving the speed of electron transport through the positive current collector 410 and making the electron transport more stable. When the thickness of the positive current collector 410 is less than or equal to 80 μm, the space occupied by the positive current collector 410 is smaller, which is conducive to improving the energy density of the cell 10. Therefore, when the thickness of the positive current collector 410 is 5 μm-80 μm, it can not only have good conductivity, which is conducive to improving the speed of electron transport through the positive current collector 410 and making the electron transport more stable, but also occupy less space, which is conducive to improving the energy density of the cell 10.

[0080] In some embodiments, the housing 100 includes a first wall and a second wall disposed opposite to each other along the thickness direction of the cell 10, and a plurality of side walls connected between the first wall and the second wall. A first electrode terminal 310 is disposed on one of the side walls and is insulated from the side wall.

[0081] In some embodiments, the first electrode terminal 310 may be square in shape, which can increase the cross-sectional area of ​​the first electrode terminal 310 when the thickness of the cell 10 is limited, thereby increasing the connection area between the first electrode terminal 310 and the positive current collector 410 and the load, and improving the connection reliability between the first electrode terminal 310 and the positive current collector 410 and the load.

[0082] In other embodiments, the first electrode terminal 310 may also be arranged in a circular or elliptical shape.

[0083] In some embodiments, the first electrode terminal 310 may be made of a material with good electrical conductivity, such as a metal material such as lead or copper.

[0084] In some embodiments, the housing 100 includes a first wall 101, and a positive current collector 410 is located between the first wall 101 and the composite electrode 200 along the second direction Y. A first insulating layer 510 is disposed between the positive current collector 410 and the first wall 101 along the second direction Y.

[0085] By positioning the positive current collector 410 between the first wall 101 and the composite electrode 200 along the second direction Y, and providing a first insulating layer 510 between the positive current collector 410 and the first wall 101 along the second direction Y, the first insulating layer 510 can provide insulation between the positive current collector 410 and the outer casing 100, reducing the possibility of short circuit between the positive current collector 410 and the outer casing 100, and improving the safety of the battery cell 10.

[0086] In some embodiments, the material of the first insulating layer 510 may be plastic, rubber, silicone, etc.

[0087] Referring to Figure 4, which is a cross-sectional structural schematic diagram of a battery cell provided in some other embodiments of this application.

[0088] In some embodiments, the battery cell 10 further includes a second electrode terminal 320, which is disposed on the housing 100 and is insulated from the housing 100. The negative electrode active material membrane 230 is electrically connected to the second electrode terminal 320, and the positive electrode active material membrane 220 is electrically connected to the housing 100.

[0089] By electrically connecting the negative electrode active material membrane 230 to the second electrode terminal 320 and the positive electrode active material membrane 220 to the outer casing 100, the load can be electrically connected to the negative electrode active material membrane 230 through the second electrode terminal 320 and to the positive electrode active material membrane 220 through the outer casing 100, thereby enabling the charging and discharging of the battery cell 10.

[0090] In some embodiments, at the first connection portion 202, the positive electrode active material film 220 is located between the negative electrode active material film 230 and the housing 100. At the second connection portion 203, the negative electrode active material film 230 is located between the positive electrode active material film 220 and the housing 100. The battery cell 10 also includes a negative electrode current collector 420, which is disposed within the housing 100. The negative electrode current collector 420 is located on one side of the composite electrode 200 along the second direction Y and is in contact with the negative electrode active material films 230 of the plurality of second connection portions 203. The second electrode terminal 320 is electrically connected to the negative electrode current collector 420. The positive electrode active material film 220 of the first connection portion 202 is in contact with the housing 100.

[0091] By positioning the negative electrode active material membrane 230 between the positive electrode active material membrane 220 and the outer casing 100 at the second connection portion 203, and placing the negative electrode current collector 420 inside the outer casing 100, the negative electrode current collector 420 is located on one side of the composite electrode 200 along the second direction Y and is in contact with the negative electrode active material membranes 230 at the multiple second connection portions 203. This results in a larger contact area between the negative electrode current collector 420 and the negative electrode active material membrane 230, a larger flow area between them, and more stable electron transport. Furthermore, due to the good conductivity of the negative electrode current collector 420, by placing the negative electrode current collector 420 and electrically connecting the second electrode terminal 320 to it, the electron transport speed between the second electrode terminal 320 and the negative electrode active material membrane 230 is faster and the stability of electron transport is better. By positioning the negative electrode current collector 420 on one side of the composite electrode 200 along the second direction Y, the farthest electron transport path within the negative electrode active material film 230 is along the second direction Y, which is the thickness direction of the battery cell. Compared to placing the negative electrode active material film 230 on one side of the composite electrode 200 along the first direction X or the third direction Z, this application can make the electron transport path shorter, which is beneficial to reducing the internal resistance of the battery cell 10 and thus improving the rate performance of the battery cell 10.

[0092] By positioning the positive electrode active material membrane 220 between the negative electrode active material membrane 230 and the outer casing 100 at the first connection portion 202, and ensuring that the positive electrode active material membrane 220 at the first connection portion 202 is in contact with the outer casing 100, the contact area between the outer casing 100 and the positive electrode active material membrane 220 is larger, the current flow area between the outer casing 100 and the positive electrode active material membrane 220 is larger, and the electron transport between the outer casing 100 and the positive electrode active material membrane 220 is more stable.

[0093] Taking lithium-ion cell 10 as an example, the material of the negative electrode current collector 420 can be copper.

[0094] In some embodiments, the housing 100 includes a first wall 101 and a second wall 102 disposed opposite to each other along the thickness direction of the cell 10, and a plurality of side walls 103. The side walls 103 are connected between the first wall 101 and the second wall 102, and the second electrode terminal 320 is disposed on one of the side walls 103 and is insulated from the side wall 103.

[0095] In some embodiments, the second electrode terminal 320 may be square in shape, which can increase the cross-sectional area of ​​the second electrode terminal 320 when the thickness of the cell 10 is limited, thereby increasing the connection area between the second electrode terminal 320 and the negative current collector 420 and the load, and improving the connection reliability between the second electrode terminal 320 and the negative current collector 420 and the load.

[0096] In other embodiments, the second electrode terminal 320 may also be arranged in a circular or elliptical shape.

[0097] In some embodiments, the second electrode terminal 320 may be made of a material with good conductivity, such as a metal material such as lead or copper.

[0098] In some embodiments, the housing 100 includes a second wall, and along the second direction Y, a negative electrode current collector 420 is located between the second wall and the composite electrode 200. A second insulating layer 520 is disposed between the negative electrode current collector 420 and the second wall along the second direction Y.

[0099] By positioning the negative current collector 420 between the second wall and the composite electrode 200 along the second direction Y, and providing a second insulating layer 520 between the negative current collector 420 and the second wall along the second direction Y, the second insulating layer 520 can provide insulation between the negative current collector 420 and the outer casing 100, reducing the possibility of short circuit between the negative current collector 420 and the outer casing 100 and improving the safety of the battery cell 10.

[0100] In some embodiments, the material of the second insulating layer 520 may be plastic, rubber, silicone, etc.

[0101] Referring to Figure 5, which is a cross-sectional structural schematic diagram of a battery cell provided in some other embodiments of this application.

[0102] In some embodiments, the battery cell 10 includes a first electrode terminal 310 and a second electrode terminal 320. The first electrode terminal 310 is disposed on and insulated from the housing 100, and the second electrode terminal 320 is disposed on and insulated from the housing 100. A positive electrode active material membrane 220 is electrically connected to the first electrode terminal 310, and a negative electrode active material membrane 230 is electrically connected to the second electrode terminal 320.

[0103] By electrically connecting the positive electrode active material membrane 220 to the first electrode terminal 310 and the negative electrode active material membrane 230 to the second electrode terminal 320, the load can be electrically connected to the positive electrode active material membrane 220 through the first electrode terminal 310 and to the negative electrode active material membrane 230 through the second electrode terminal 320, thereby enabling the charging and discharging of the battery cell 10.

[0104] Referring to Figure 6, which is a cross-sectional structural schematic diagram of a battery cell provided in some other embodiments of this application.

[0105] In some embodiments, the housing 100 includes a first housing 110 and a second housing 120, which are insulated from each other. The positive electrode active material membrane 220 is electrically connected to the first housing 110, and the negative electrode active material membrane 230 is electrically connected to the second housing 120.

[0106] By making the first housing 110 and the second housing 120 insulated from each other, the positive active material membrane 220 is electrically connected to the first housing 110, and the negative active material membrane 230 is electrically connected to the second housing 120. This allows the load to be electrically connected to the positive active material membrane 220 through the first housing 110 and to the negative active material membrane 230 through the second housing 120, thereby enabling the charging and discharging of the battery cell 10.

[0107] In some embodiments, the housing 100 includes an insulating member 130 disposed between the first housing 110 and the second housing 120 along the second direction Y, for achieving an insulating connection between the first housing 110 and the second housing 120.

[0108] In some embodiments, the insulating element 130 may be made of plastic, rubber, silicone, etc.

[0109] In some embodiments, at the first connection portion 202, the positive electrode active material membrane 220 is located between the negative electrode active material membrane 230 and the first housing 110. At the second connection portion 203, the negative electrode active material membrane 230 is located between the positive electrode active material membrane 220 and the second housing 120. The positive electrode active material membrane 220 of the first connection portion 202 is in contact with the first housing 110. The negative electrode active material membrane 230 of the second connection portion 203 is in contact with the second housing 120.

[0110] By positioning the positive electrode active material membrane 220 between the negative electrode active material membrane 230 and the first housing 110 at the first connection portion 202, and ensuring that the positive electrode active material membrane 220 of the first connection portion 202 is in contact with the first housing 110, the contact area between the first housing 110 and the positive electrode active material membrane 220 is larger, the flow area between the first housing 110 and the positive electrode active material membrane 220 is larger, and the electron transport between the first housing 110 and the positive electrode active material membrane 220 is more stable. By positioning the negative electrode active material membrane 230 between the positive electrode active material membrane 220 and the second housing 120 at the second connection portion 203, and ensuring that the negative electrode active material membrane 230 is in contact with the second housing 120, the contact area between the second housing 120 and the negative electrode active material membrane 230 is larger, resulting in a larger current flow area between them. This leads to more stable electron transport between the second housing 120 and the negative electrode active material membrane 230, and the direct connection with the housing eliminates the need for a current collector, thereby increasing the energy density of the battery cell.

[0111] Referring to Figure 1, in some embodiments, the height of the composite electrode 200 along the second direction Y is H1, satisfying 2mm ≤ H1 ≤ 10mm. For example, H1 can be 2mm, 4mm, 6mm, 7mm, or 10mm, etc.

[0112] When H1 is greater than or equal to 2 mm, it facilitates the folding and forming of the composite electrode 200, reducing the difficulty of manufacturing the cell 10. When H1 is less than or equal to 10 mm, the electrons inside the cell 10 can travel along the second direction with a shorter path, resulting in lower internal resistance, which is beneficial for improving the rate performance of the cell 10. It also allows for a smaller thickness of the cell 10, making it suitable for various electrical devices. Therefore, when 2 mm ≤ H1 ≤ 10 mm, it facilitates the folding and forming of the composite electrode 200, reducing the difficulty of manufacturing the cell 10. It also allows for a shorter path, lower internal resistance, and improved rate performance of the cell 10. Furthermore, it allows for a smaller thickness of the cell 10, making it suitable for various electrical devices.

[0113] Referring to Figures 7 and 8, Figure 7 is a cross-sectional structural schematic diagram of a battery cell provided in some other embodiments of this application; Figure 8 is a structural schematic diagram of a battery cell after the composite electrode sheet is unfolded in some other embodiments of this application.

[0114] In some embodiments, the composite electrode 200 further includes a positive conductive layer 240, which is disposed on the side of the positive active material membrane 220 facing away from the separator 210.

[0115] By setting a positive conductive layer 240 and placing it on the side of the positive active material film 220 facing away from the separator 210, electrons can be transported within the positive active material film 220 along the first direction X. Furthermore, electrons only need to pass through a single layer of the positive active material film 220 in the first direction X. Compared to the positive active material film 220 being electrically connected to the outside via the first connection portion 202, where electrons are transported within the positive active material film 220 along the second direction Y, this solution shortens the electron transport path within the positive active material film 220, improves the low conductivity of the positive active material film 220, reduces the internal resistance of the cell 10, and helps improve the rate performance of the cell 10.

[0116] In some embodiments, the thickness of the positive conductive layer 240 is H2, satisfying 0.5μm≤H2≤2μm. For example, H2 can be 0.5μm, 1μm, or 2μm, etc.

[0117] When H2 is greater than or equal to 0.5 μm, the positive electrode conductive layer 240 has a larger overcurrent area and better conductivity, which is beneficial to increasing the speed of electron transport through the positive electrode conductive layer 240 and making the electron transport more stable. When H2 is less than or equal to 2 μm, the positive electrode conductive layer 240 occupies less space, which is beneficial to increasing the energy density of the cell 10. Therefore, when 0.5 μm ≤ H2 ≤ 2 μm, the positive electrode conductive layer 240 has better conductivity, which is beneficial to increasing the speed of electron transport through the positive electrode conductive layer 240 and making the electron transport more stable, and the positive electrode conductive layer 240 occupies less space, which is beneficial to increasing the energy density of the cell 10.

[0118] In some embodiments, the material of the positive electrode conductive layer 240 includes a conductive metal and / or conductive carbon. The conductive metal can be aluminum, silver, nickel, etc., and the conductive carbon can be carbon nanotubes, conductive carbon black, conductive graphite, etc.

[0119] By making the material of the positive electrode conductive layer 240 include conductive metals and / or conductive carbon, the conductivity of the positive electrode conductive layer 240 can be improved, which is beneficial to increasing the speed of electron transmission through the positive electrode conductive layer 240 and making the electron transmission more stable.

[0120] In some embodiments, the surface sheet resistance of the positive electrode conductive layer 240 is 10 mΩ / mm² to 50 mΩ / mm². For example, the surface sheet resistance of the positive electrode conductive layer 240 can be 10 mΩ / mm², 30 mΩ / mm², or 50 mΩ / mm², etc.

[0121] When the surface sheet resistance of the positive electrode conductive layer 240 is greater than or equal to 10 mΩ / mm², it facilitates the fabrication of the positive electrode conductive layer 240. When the surface sheet resistance of the positive electrode conductive layer 240 is less than or equal to 50 mΩ / mm², it results in better conductivity, which is beneficial for increasing the speed of electron transport through the positive electrode conductive layer 240 and improving the stability of electron transport. Therefore, when the surface sheet resistance of the positive electrode conductive layer 240 is between 10 mΩ / mm² and 50 mΩ / mm², it facilitates the fabrication of the positive electrode conductive layer 240, ensures better conductivity, and improves the speed of electron transport through the positive electrode conductive layer 240, resulting in higher stability of electron transport.

[0122] In some embodiments, the resistivity ρ of the positive electrode active material film 220 along the second direction satisfies 0.1 Ω·cm ≤ ρ ≤ 10 Ω·cm. For example, ρ can be 0.1 Ω·cm, 5 Ω·cm, or 10 Ω·cm, etc.

[0123] When ρ is greater than or equal to 0.1 Ω·cm, it facilitates the preparation of the positive electrode active material film 220; when ρ is less than or equal to 10 Ω·cm, it improves the conductivity of the positive electrode active material film 220, which is beneficial to increasing the speed of electron transport through the positive electrode active material film 220 and making the electron transport more stable; therefore, when 0.1 Ω·cm ≤ ρ ≤ 10 Ω·cm, it facilitates the preparation of the positive electrode active material film 220, improves the conductivity of the positive electrode active material film 220, improves the speed of electron transport through the positive electrode active material film 220, and makes the electron transport more stable.

[0124] The specific test method for the resistivity of the above-mentioned positive electrode active material film 220 along the second direction Y is as follows.

[0125] Specific testing method: As shown in Figure 9, the two-probe method transmits current through the positive electrode active material membrane 220 to the conductive layer interface, and then through the transverse conductive layer to the other terminal being tested. The two terminals are placed on the positive electrode active material membrane 220 along the second direction. The terminals can be moved to different positions as needed.

[0126] In some embodiments, the positive electrode active material membrane 220 includes a conductive agent, the content of which is Q, satisfying 0.5% ≤ Q ≤ 5.0%. For example, Q can be 0.5%, 3.0%, or 5.0%, etc.

[0127] When Q is greater than or equal to 0.5%, the conductivity of the positive electrode active material film 220 is better, which is beneficial to increasing the speed of electron transmission through the positive electrode conductive layer 240 and making the electron transmission more stable. When Q is less than or equal to 5.0%, the proportion of other materials in the positive electrode active material film 220 used to realize metal ion insertion and extraction is higher, which is beneficial to increasing the energy density of the cell 10. Therefore, when 0.5% ≤ Q ≤ 5.0%, the conductivity of the positive electrode active material film 220 is better, which is beneficial to increasing the speed of electron transmission through the positive electrode conductive layer 240 and making the electron transmission more stable, and it is also beneficial to increasing the energy density of the cell 10.

[0128] This application provides an electrical device including a battery cell 10 according to any of the above schemes, the battery cell 10 being used to provide electrical energy.

[0129] The electrical equipment can be any of the aforementioned devices or systems using battery cell 10.

[0130] In some embodiments, the battery cell 10 further includes a first electrode terminal 310 and a positive current collector 410. The first electrode terminal 310 is disposed in the housing 100 and is insulated from the housing 100. The positive current collector 410 is disposed inside the housing 100, located on one side of the composite electrode 200 along the second direction Y, and in contact with the positive active material membrane 220. The first electrode terminal 310 is electrically connected to the positive current collector 410. The negative active material membrane 230 is in contact with the housing 100. The electrical device includes a load, which is connected to the first electrode terminal 310 and the housing 100.

[0131] By setting a first electrode terminal 310 and a positive current collector 410, and making the first electrode terminal 310 disposed in the housing 100 and insulated from the housing 100, the positive current collector 410 is disposed inside the housing 100 and located on one side of the composite electrode 200 along the second direction Y and in contact with the positive active material membrane 220, the first electrode terminal 310 is electrically connected to the positive current collector 410, the negative active material membrane 230 is in contact with the housing 100, and the load is connected to the first electrode terminal 310 and the housing 100, so that the load can be electrically connected to the positive active material membrane 220 through the first electrode terminal 310 and the positive current collector 410, and electrically connected to the negative active material membrane 230 through the housing 100, thereby enabling the charging and discharging of the battery cell 10.

[0132] This application provides a method for preparing a battery cell, comprising:

[0133] S610, Prepare the positive electrode active material membrane.

[0134] S620, Preparation of negative electrode active material membrane.

[0135] S630. The positive electrode active material film and the negative electrode active material film are respectively disposed on both sides of the film. The positive electrode active material film, the separator and the negative electrode active material film are hot-pressed to connect the positive electrode active material film and the negative electrode active material film to the separator to form a composite electrode.

[0136] S640. The composite electrode sheet is bent into a multi-layered continuous folded structure, such that the composite electrode sheet includes multiple folded portions, a first connecting portion, and a second connecting portion. The multiple folded portions are stacked along a first direction. The first connecting portion and the second connecting portion are respectively located at both ends of the folded portions along a second direction. The first connecting portion connects two adjacent folded portions, and the second connecting portion connects two adjacent folded portions. The first direction is perpendicular to the second direction.

[0137] S650: The composite electrode is housed in the casing, so that the positive electrode active material film and / or the negative electrode active material film are electrically connected to the casing. The second direction is the thickness direction of the battery cell.

[0138] By making the composite electrode include a separator, a positive electrode active material film, and a negative electrode active material film, with the positive and negative electrode active material films respectively disposed on both sides of the separator, the space occupied by the positive and negative electrode current collectors can be eliminated, resulting in a larger volume proportion of the positive and negative electrode active material films in the battery cell, thereby increasing the energy density of the battery cell. By making the composite electrode have a multi-layer continuous folded structure, the composite electrode includes multiple folded portions, a first connecting portion, and a second connecting portion. The multiple folded portions are stacked along a first direction, and the first and second connecting portions are respectively located at the two ends of the folded portions along a second direction. The first connecting portion connects one end of two adjacent folded portions, and the second connecting portion connects the other end of two adjacent folded portions, which facilitates the housing of the composite electrode within the outer casing. Since the farthest electron transport path within the positive electrode active material membrane and / or negative electrode active material membrane is from the side closest to the separator outwards, by electrically connecting the positive electrode active material membrane and / or negative electrode active material membrane to the outer casing, the farthest electron transport path within the positive electrode active material membrane and / or negative electrode active material membrane is transported along a second direction. Relative to the second direction being the length or width direction of the battery cell, this application sets the second direction as the thickness direction of the battery cell. This allows the battery cell to be smaller in the second direction, i.e., the electron transport path in the second direction is shorter, which is beneficial for reducing the internal resistance of the battery cell, thereby improving the rate performance of the battery cell.

[0139] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0140] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery cell, characterized in that, The device includes a housing and a composite electrode, wherein the composite electrode is housed in the housing and the composite electrode includes a separator, a positive active material membrane, and a negative active material membrane, wherein the positive active material membrane and the negative active material membrane are respectively disposed on both sides of the separator. The composite electrode sheet has a multi-layer continuous folded structure, including multiple folded portions, a first connecting portion and a second connecting portion. The multiple folded portions are stacked along a first direction. The first connecting portion and the second connecting portion are respectively located at both ends of the folded portion along a second direction. The first connecting portion connects one end of two adjacent folded portions, and the second connecting portion connects the other end of two adjacent folded portions. The positive electrode active material membrane and / or the negative electrode active material membrane are electrically connected to the outer shell; The second direction is the thickness direction of the battery cell, and the first direction is perpendicular to the second direction.

2. The battery cell according to claim 1, characterized in that, The battery cell also includes a first electrode terminal, which is disposed on the housing and is insulated from the housing. The positive electrode active material membrane is electrically connected to the first electrode terminal, and the negative electrode active material membrane is electrically connected to the outer shell.

3. The battery cell according to claim 2, characterized in that, In the first connection portion, the positive electrode active material membrane is located between the negative electrode active material membrane and the outer shell; in the second connection portion, the negative electrode active material membrane is located between the positive electrode active material membrane and the outer shell. The battery cell also includes a positive current collector, which is disposed inside the housing. The positive current collector is located on one side of the composite electrode along the second direction and is in contact with the positive active material film of the plurality of first connection portions. The first electrode terminal is electrically connected to the positive current collector. The negative electrode active material membrane of the second connection portion is in contact with the outer shell.

4. The battery cell according to claim 3, characterized in that, The outer casing includes a first wall, and along the second direction, the positive current collector is located between the first wall and the composite electrode sheet; Along the second direction, a first insulating layer is provided between the positive current collector and the first wall.

5. The battery cell according to claim 1, characterized in that, The battery cell also includes a second electrode terminal, which is disposed on the housing and is insulated from the housing. The negative electrode active material membrane is electrically connected to the second electrode terminal, and the positive electrode active material membrane is electrically connected to the outer shell.

6. The battery cell according to claim 5, characterized in that, In the first connection portion, the positive electrode active material membrane is located between the negative electrode active material membrane and the outer shell; in the second connection portion, the negative electrode active material membrane is located between the positive electrode active material membrane and the outer shell. The battery cell also includes a negative electrode current collector, which is disposed inside the housing. The negative electrode current collector is located on one side of the composite electrode along the second direction and is in contact with the negative electrode active material film of the plurality of second connection portions. The second electrode terminal is electrically connected to the negative electrode current collector. The positive electrode active material membrane of the first connection portion is in contact with the outer shell.

7. The battery cell according to claim 6, characterized in that, The outer casing includes a second wall, and along the second direction, the negative electrode current collector is located between the second wall and the composite electrode sheet; Along the second direction, a second insulating layer is provided between the negative electrode current collector and the second wall.

8. The battery cell according to claim 1, characterized in that, The outer casing includes a first casing and a second casing, which are insulated from each other. The positive electrode active material membrane is electrically connected to the first housing, and the negative electrode active material membrane is electrically connected to the second housing.

9. The battery cell according to claim 8, characterized in that, In the first connection portion, the positive electrode active material membrane is located between the negative electrode active material membrane and the first housing; in the second connection portion, the negative electrode active material membrane is located between the positive electrode active material membrane and the second housing. The positive electrode active material membrane of the first connecting portion is in contact with the first housing; The negative electrode active material membrane of the second connection portion is in contact with the second housing.

10. The battery cell according to claim 1, characterized in that, The height of the composite electrode along the second direction is H1, which satisfies 2mm≤H1≤10mm.

11. The battery cell according to claim 1, characterized in that, The composite electrode also includes a positive conductive layer, which is disposed on the side of the positive active material membrane facing away from the separator.

12. The battery cell according to claim 11, characterized in that, The thickness of the positive electrode conductive layer is H2, which satisfies 0.5μm≤H2≤2μm.

13. The battery cell according to claim 11, characterized in that, The material of the positive electrode conductive layer includes conductive metals and / or conductive carbon.

14. The battery cell according to any one of claims 1-13, characterized in that, The resistivity of the positive electrode active material film along the second direction is ρ, which satisfies 0.1Ω·cm≤ρ≤10.0Ω·cm.

15. The battery cell according to any one of claims 1-13, characterized in that, The positive electrode active material membrane includes a conductive agent, and the content of the conductive agent is Q, which satisfies 0.5% ≤ Q ≤ 5.0%.

16. An electrical appliance, characterized in that, Includes a battery cell as described in any one of claims 1-15, the battery cell being used to provide electrical energy.

17. The electrical equipment according to claim 16, characterized in that, The battery cell also includes a first electrode terminal and a positive current collector. The first electrode terminal is disposed on the outer casing and is insulated from the outer casing. The positive current collector is disposed inside the housing, located on one side of the composite electrode along the second direction, and in contact with the positive active material film; the first electrode terminal is electrically connected to the positive current collector; the negative active material film is in contact with the housing. The electrical equipment includes a load, which is connected to the first electrode terminal and the housing.

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