Secondary battery cell, secondary battery and electric apparatus

Abstract

A secondary battery cell, a secondary battery and an electric apparatus. The secondary battery cell comprises: a stacked electrode assembly, which comprises a positive electrode sheet, a negative electrode sheet and a separator, wherein the positive electrode sheet comprises a positive electrode film layer, the positive electrode film layer comprises a positive electrode active material, the negative electrode sheet comprises a negative electrode film layer, and the negative electrode film layer comprises a negative electrode active material; the positive electrode active material comprises a lithium-containing transition metal phosphate and a lithium-containing transition metal oxide; and the thickness h of the separator satisfies: 8 μm≤h≤21 μm. The secondary battery cell can achieve both high energy density and good safety performance.

Description

Secondary battery cells, secondary batteries and electrical devices Cross-references to related applications

[0001] This patent document claims priority and benefit to Chinese Patent Application No. 202411650005.9, filed on November 18, 2024, entitled "Secondary Battery Cell, Secondary Battery and Electrical Device". The entire contents of the aforementioned patent application are incorporated herein by reference as a part of the disclosure of this patent document. Technical Field

[0002] This application relates to the field of batteries, and more specifically, to a secondary battery cell, a secondary battery, and an electrical device. Background Technology

[0003] In recent years, secondary batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power plants, as well as in many fields such as power tools, electric bicycles, electric motorcycles, electric cars, military equipment, and aerospace, thus achieving great development.

[0004] Improving the energy density of rechargeable battery cells is a key research focus in the battery field. Currently, the energy density of rechargeable batteries is mainly limited by the positive electrode active material, and this is usually achieved by combining different positive electrode active materials. However, while increasing energy density, the use of mixed positive electrode active materials may affect other properties of the rechargeable battery cell, such as cycle performance and safety performance. Therefore, how to balance the energy density and safety performance of rechargeable battery cells has become an urgent technical problem to be solved. Summary of the Invention

[0005] This application is made in view of the above-mentioned technical problems, and its purpose is to provide a secondary battery cell, a secondary battery, and an electrical device, wherein the secondary battery cell can achieve both high energy density and good safety performance.

[0006] In a first aspect, a secondary battery cell is provided, the secondary battery cell comprising: a stacked electrode assembly, including a positive electrode, a negative electrode, and a separator, wherein the positive electrode includes a positive electrode film layer, the positive electrode film layer includes a positive electrode active material, the negative electrode includes a negative electrode film layer, the negative electrode film layer includes a negative electrode active material; the positive electrode active material includes a lithium-containing transition metal phosphate and a lithium-containing transition metal oxide; the thickness h of the separator satisfies: 8μm≤h≤21μm.

[0007] In the embodiments of this application, the positive electrode active material includes lithium-containing transition metal phosphate and lithium-containing transition metal oxide. A stacked electrode assembly is used and the thickness of the separator is controlled within a specific range of 8μm-12μm. As a result, the energy density of the secondary battery cell can be improved and the safety performance can be enhanced.

[0008] In one possible implementation, the mass content m1 of the lithium transition metal phosphate, based on the total mass of the positive electrode active material, satisfies: 40wt% ≤ m1 ≤ 70wt%.

[0009] By controlling the mass content of lithium transition metal phosphates in the positive electrode active material within a suitable range, it is helpful to further improve the energy density and safety performance of secondary battery cells.

[0010] In one possible implementation, the isolation membrane includes a base membrane and a coating disposed on at least one side of the base membrane, wherein the thickness h1 of the coating on one side satisfies: 3μm≤h1≤6μm.

[0011] In the embodiments of this application, by controlling the thickness of the coating within a suitable range, the mechanical strength of the separator can be improved, while meeting the wetting requirements of the electrolyte, thus helping to improve the safety performance of the secondary battery cell.

[0012] In one possible implementation, the coating comprises heat-resistant particles, which include at least one of inorganic particles and organic particles.

[0013] In one possible implementation, the inorganic particles include at least one of aluminum oxide, silicon oxide, titanium oxide, and barium titanate.

[0014] Inorganic particles possess excellent thermal stability. As a coating for the separator, they can provide good support for the base membrane during the cycling process of the secondary battery cell, reducing the risk of thermal shrinkage of the base membrane during cycling and improving the thermal stability of the separator. This can further improve the thermal stability of the secondary battery cell.

[0015] In one possible implementation, the coating comprises binder particles, which include: polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylonitrile, polyethylene oxide, copolymers of different fluorinated alkenyl monomer units, copolymers of fluorinated alkenyl monomer units and vinyl monomer units, copolymers of fluorinated alkenyl monomer units and acrylic monomer units, copolymers of fluorinated alkenyl monomer units and acrylate monomer units, and one or more of the modified compounds of the above homopolymers or copolymers.

[0016] In one possible implementation, the stacked electrode assembly includes multiple positive electrode sheets and multiple negative electrode sheets, with the multiple positive electrode sheets and multiple negative electrode sheets alternately stacked along the thickness direction.

[0017] In one possible implementation, the adhesive particles' loading 'a' on one side of the release membrane satisfies: 0.5 mg / 1540.25 mm.2 ≤a≤1.2mg / 1540.25mm 2 .

[0018] In the embodiments of this application, by controlling the load of polyvinylidene fluoride on the separator within a suitable range, the adhesion between the separator and the electrode can be improved, thereby enhancing the structural stability of the stacked motor assembly and further improving the safety performance of the secondary battery.

[0019] In one possible implementation, the positive electrode includes a conductive agent, which includes carbon nanotubes, wherein the diameter l of the carbon nanotubes satisfies: 7nm ≤ l ≤ 13nm.

[0020] In the embodiments of this application, by selecting carbon nanotubes with a diameter within a suitable range as conductive agents, a conductive network between the conductive agent and the positive electrode active material can be constructed, thereby improving the rate performance and cycle performance of the secondary battery cell.

[0021] In one possible implementation, the average particle size D1 of the lithium transition metal oxide particles satisfies: 2μm≤D1≤5μm.

[0022] In the embodiments of this application, by controlling the average particle size of the lithium transition metal oxide particles to be in the range of 2μm-5μm, the lithium transition metal oxide can have better structural stability, improve the thermal stability of the lithium transition metal oxide, and further enhance the safety performance of the secondary battery cell.

[0023] In one possible implementation, the lithium-containing transition metal oxide includes: Li 1+c [Ni x Co y Mn z M d ]O 2-e Wherein, M includes at least one of Zr, Al, Ti, Sb, Nb, Te, Mg, B, Ca, V, Ta or Sr, 0.2≥c≥-0.2, 0.95≥x≥0.5, 0.2≥y≥0.05, 0.3>z>0, 0.3>d≥0, 0.5≥e≥0.

[0024] In the embodiments of this application, by selecting lithium-containing transition metal oxides doped or coated with heteroatoms, the thermal stability of lithium-containing transition metal oxides can be improved, thereby further enhancing the safety performance of secondary battery cells.

[0025] In one possible implementation, the positive electrode sheet satisfies at least one of the following (1)-(3): (1) The compaction density ρ1 of the positive electrode sheet satisfies: 2.5 g / cm³ 3 ≤ρ1≤2.9g / cm3 (2) The single-sided coating weight CW1 of the positive electrode film layer satisfies: 190 g / m 2 ≤CW1≤230g / m 2 (3) The thickness h1 of the positive current collector satisfies: 10μm≤h1≤13μm.

[0026] In the embodiments of this application, by controlling the compaction density of the positive electrode sheet and the coating weight of the positive electrode film within a suitable range, it is helpful to improve lithium-ion dynamics, thereby reducing the polarization of the secondary battery cell during cycling and helping to improve the safety performance of the secondary battery cell; by controlling the thickness of the positive electrode current collector within a suitable range, it is helpful to reduce the thickness of the positive electrode sheet and help to improve the energy density of the secondary battery cell.

[0027] In one possible implementation, the negative electrode sheet satisfies at least one of the following (4)-(6): (4) The compaction density ρ2 of the negative electrode sheet satisfies: 1.3 g / cm³ 3 ≤ρ2≤1.55g / cm 3 (5) The single-sided coating weight CW2 of the negative electrode film layer satisfies: 90 g / m 2 ≤CW2≤110g / m 2 (6) The thickness h2 of the negative electrode current collector satisfies: 4μm≤h2≤6μm.

[0028] In the embodiments of this application, by controlling the compaction density of the negative electrode sheet and the coating weight of the negative electrode film within a suitable range, it is helpful to improve lithium-ion dynamics, thereby reducing the polarization of the secondary battery cell during cycling and helping to improve the safety performance of the secondary battery cell; by controlling the thickness of the negative electrode current collector within a suitable range, it is helpful to reduce the thickness of the negative electrode sheet and help to improve the energy density of the secondary battery cell.

[0029] In one possible implementation, the negative electrode active material comprises graphite, wherein the average volumetric particle size Dv50 of the graphite satisfies: 10μm≤Dv50≤14μm.

[0030] In the embodiments of this application, by controlling the average volume particle size of graphite within a suitable range, it is helpful to improve lithium-ion dynamics, reduce the polarization of secondary battery cells during cycling, and improve the safety performance of secondary battery cells.

[0031] In one possible implementation, the secondary battery includes an electrolyte comprising a solvent comprising linear carbonate; the mass content m2 of the linear carbonate, based on the total mass of the electrolyte, satisfies 40wt% ≤ m2 ≤ 70wt%.

[0032] In the embodiments of this application, by selecting linear carboxylic acid esters as solvents and controlling their mass content in the electrolyte within a suitable range, it is helpful to reduce the viscosity of the electrolyte, thereby helping to improve lithium-ion kinetics.

[0033] In one possible implementation, the electrolyte comprises a lithium salt, which includes LiPF6 and LiFSI; the mass content of the lithium salt, m3, based on the total mass of the electrolyte, satisfies 13wt% ≤ m3 ≤ 18wt%.

[0034] In the embodiments of this application, by selecting LiPF6 and LiFSI as lithium salts, it is helpful to improve the lithium-ion conductivity and thermal stability of the electrolyte, thereby helping to improve the lithium-ion kinetics during the cycling process of the secondary battery cell, reduce the polarization of the secondary battery cell during the cycling process, and improve the safety performance of the secondary battery cell.

[0035] In one possible implementation, the ionic conductivity σ of the electrolyte at 25°C satisfies: 7 mS / cm ≤ σ ≤ 10 mS / cm.

[0036] In the embodiments of this application, selecting an electrolyte with high ionic conductivity helps to improve lithium-ion kinetics during the cycling process of a secondary battery cell, helps to reduce polarization of the secondary battery cell during cycling, and improves the safety performance of the secondary battery cell.

[0037] In one possible implementation, the secondary battery cell includes a casing and a current collector; the casing is used to house the stacked electrode assembly, and the casing includes a first wall with electrode terminals disposed thereon; the stacked electrode assembly includes a body and tabs, the tabs being connected to the end of the body facing the first wall; the current collector is disposed between the first wall and the body, and the current collector includes a first connecting portion and a second connecting portion connected to each other, the first connecting portion being connected to the electrode terminals, the second connecting portion being connected to the tabs, and the thickness of the first connecting portion being greater than the thickness of the second connecting portion along the thickness direction of the first wall.

[0038] In the embodiments of this application, by setting the thickness of the first connecting portion of the current collector to be greater than the thickness of the second connecting portion, the thickness of the area where the current collector is connected to the electrode terminal is greater than the thickness of the area where the current collector is connected to the tab. Since the thickness requirement of the area where the current collector is connected to the tab is less than the thickness requirement of the area where the current collector is connected to the electrode terminal, the thickness of the current collector can be effectively optimized while enabling the current collector to connect to the electrode terminal and the tab. This reduces the overall weight of the current collector and saves the space occupied by the current collector, thereby optimizing the weight and internal space utilization of the secondary battery cell and further improving the energy density of the secondary battery cell.

[0039] In one possible implementation, along the thickness direction of the current collecting member, the thickness D1 of the first connecting part satisfies: 0.5mm≤D1≤1.2mm; and the thickness D2 of the second connecting part satisfies: 0.3mm≤D2≤1mm.

[0040] In the embodiments of this application, by controlling the thickness of the first connecting part and the thickness of the second connecting part within a suitable range, it is possible to improve the energy density of the secondary battery cell while satisfying the connection strength between the first connecting part and the electrode terminal, and between the second connecting part and the tab.

[0041] In one possible implementation, 0.1mm ≤ D1 - D2 ≤ 0.9mm.

[0042] In the embodiments of this application, by setting the thickness of the first connecting part to be within the range of 0.1mm-0.9mm greater than the thickness of the second connecting part, the thickness of the current collector component used to connect with the electrode tab can be further reduced, thereby further optimizing the thickness of the current collector component, reducing the overall weight of the current collector component and saving the space occupied by the current collector component. This is beneficial to further reduce the weight of the secondary battery cell and improve the internal space utilization of the secondary battery cell, thereby improving the energy density of the secondary battery cell.

[0043] In one possible implementation, the first wall includes a first through hole; the electrode terminal includes a main body and a stepped portion, at least a portion of the main body passes through the first through hole, the stepped portion protrudes from the outer peripheral surface of the main body, and the stepped portion is located on the side of the first wall facing the outside of the secondary battery cell; the secondary battery cell includes a fixing member, the fixing member including a second through hole through which the main body passes; in the thickness direction of the first wall, at least a portion of the fixing member is located between the first wall and the stepped portion and abuts against the stepped portion, the main body has a first end face facing the outside of the secondary battery cell, the fixing member has a second end face facing the outside of the secondary battery cell, and the first end face extends beyond the second end face.

[0044] In the embodiments of this application, by designing the structure of the electrode terminals, the surface of the secondary battery cell that extends beyond the outer surface of the first wall to the maximum height is the first end face. When using electrode terminals of the same specifications, the height of the secondary battery cell extending beyond the first wall can be reduced accordingly, thereby increasing the proportion of the space inside the secondary battery cell casing to the total space of the battery and thus improving the energy density of the battery.

[0045] In one possible implementation, the height difference H between the first end face and the second end face in the thickness direction of the first wall satisfies: 0.5mm ≤ H ≤ 1.5mm.

[0046] In the embodiments of this application, by controlling the height difference between the first end face and the second end face within a suitable range in the thickness direction of the first wall, the energy density of the battery can be improved while ensuring good connection stability between the first end face and the second end face.

[0047] In one possible implementation, the step portion protrudes from the outer peripheral surface of the main body portion by a dimension W1 that satisfies: 0.1mm ≤ W1 ≤ 5mm in the radial direction of the main body portion.

[0048] In the embodiments of this application, by controlling the size of the step portion protruding from the outer peripheral surface of the main body within a suitable range, it is beneficial to increase the contact area between the step portion and the fastener, thereby improving the connection strength between the step portion and the fastener.

[0049] In a second aspect, a secondary battery is provided, the secondary battery comprising a secondary battery cell in any of the implementable embodiments of the first aspect.

[0050] Thirdly, an electrical device is provided, the electrical device comprising a secondary battery cell in any of the implementable embodiments of the first aspect, and / or a secondary battery in the second aspect. Attached Figure Description

[0051] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0052] Figure 1 is a cross-sectional schematic diagram of a stacked electrode assembly.

[0053] Figure 2 is a cross-sectional schematic diagram of another type of stacked electrode assembly.

[0054] Figure 3 is a cross-sectional schematic diagram of a wound electrode assembly.

[0055] Figure 4 is a schematic structural diagram of a secondary battery cell.

[0056] Figure 5 is an exploded view of the secondary battery cell shown in Figure 4.

[0057] Figure 6 is a partial schematic diagram of a secondary battery cell.

[0058] Figure 7 is a partial exploded view of a secondary battery cell.

[0059] Figure 8 is a partial cross-sectional view of a secondary battery cell.

[0060] Figure 9 is a schematic diagram of a local area in Figure 8.

[0061] Figure 10 is a schematic diagram of a secondary battery. Detailed Implementation

[0062] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the secondary battery cell, secondary battery, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0063] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0064] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicating orientation or positional relationships are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0065] Unless otherwise specified, in this application, the phrase "A and / or B" means "A, B, or both A and B". More specifically, the condition "A and / or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0066] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0067] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0068] Unless otherwise specified, the following terms have the following meanings. Any undefined terms have their technically accepted meanings.

[0069] If mentioned, "lithium-containing phosphates" refers to a class of salts that include lithium and phosphate ions.

[0070] When "lithium-containing phosphates" further include transition metals, they can be called "lithium-containing transition metal phosphates".

[0071] "Lithium-containing transition metal phosphates" can include, for example, lithium iron phosphate materials and lithium manganese iron phosphate materials.

[0072] As mentioned, "lithium-containing transition metal oxides" refers to a class of oxides that include lithium and transition metal elements. Structurally, this includes ternary materials with layered structures, such as LiCoO2 and LiNiO2, as well as LiMn2O4 with a spinel structure. Ternary materials refer to lithium transition metal oxides containing three different transition metal elements. It should be understood that ternary materials can also be doped with trace amounts of other transition metal elements; generally, ternary materials doped with other transition metal elements are still considered ternary materials.

[0073] If mentioned, "linear carbonates" refer to a class of substances with a chain structure containing carbonate groups (-OCO-O-). Examples include dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC).

[0074] The embodiments of this application will be described next.

[0075] In recent years, rechargeable batteries have been widely used in power tools, electronic products, electric vehicles, aerospace, and many other fields, representing a crucial area for the development of new energy. Typically, a rechargeable battery cell includes a positive electrode, a negative electrode, an electrolyte, and a separator. During the charging and discharging process of a rechargeable battery cell, active ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte acts as a conductor of active ions between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through, ensuring the normal electrochemical reactions within the rechargeable battery cell.

[0076] Improving the energy density of rechargeable battery cells has always been a key research focus in the battery field. The cathode active material is one of the direct factors affecting the energy density of a battery cell. Current research on energy density focuses on improving the specific capacity of the cathode active material. However, improvements in energy density often come at the cost of other battery performance aspects, such as safety. From a practical application perspective, safety is a crucial performance indicator that cannot be ignored for rechargeable battery cells. Existing methods for improving safety typically only consider material blending, often at the expense of energy density, failing to achieve a balance between energy density and safety.

[0077] In view of this, embodiments of this application provide a secondary battery cell, a secondary battery, and an electrical device, wherein the secondary battery cell can balance high energy density and good safety performance.

[0078] Next, the secondary battery cell provided in this application will be introduced.

[0079] [Secondary battery cell]

[0080] First, a secondary battery cell is provided, comprising a stacked electrode assembly, which includes a positive electrode, a negative electrode, and a separator. The positive electrode includes a positive electrode film layer comprising a positive active material, and the negative electrode includes a negative electrode film layer comprising a negative active material. The positive active material includes lithium-containing transition metal phosphate and lithium-containing transition metal oxide. The thickness h of the separator satisfies: 8 μm ≤ h ≤ 21 μm.

[0081] Specifically, h can be 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, or a value within the range obtained by any combination of the above two values.

[0082] Figures 1 and 2 are schematic cross-sectional views of a stacked electrode assembly. Figure 3 is a schematic cross-sectional view of a wound electrode assembly. For ease of explanation, the tabs of each electrode are not shown here. As shown in Figures 1-3, the stacked electrode assembly 10 includes a positive electrode 11 and a negative electrode 12, as well as a separator 13 disposed between the positive electrode 11 and the negative electrode 12.

[0083] In one embodiment, as shown in FIG1, the stacked electrode assembly 10 includes a plurality of positive electrode sheets 11 and a plurality of negative electrode sheets 12; the plurality of positive electrode sheets 11 and the plurality of negative electrode sheets 12 are alternately stacked in the direction indicated by the arrows in the figure. In another embodiment, as shown in FIG2, the stacked electrode assembly 10 includes a plurality of positive electrode sheets 11 and a plurality of negative electrode sheets 12, wherein the negative electrode sheet 12 may include at least one bent section and a plurality of stacked sections, each bent section being used to connect two stacked sections, and the plurality of positive electrode sheets 11 and the plurality of stacked sections of the negative electrode sheets 12 are alternately stacked in the direction indicated by the arrows in the figure to form another stacked electrode assembly 10. Alternatively, the stacked electrode assembly 10 includes a plurality of negative electrode sheets 12 and a plurality of positive electrode sheets 11, wherein the positive electrode sheet 11 may include at least one bent section and a plurality of stacked sections, each bent section being used to connect two stacked sections, and the plurality of negative electrode sheets 12 and the plurality of stacked sections of the positive electrode sheets 11 are alternately stacked in the direction indicated by the arrows in the figure.

[0084] Figure 3 illustrates a wound electrode assembly. The positive electrode 11, separator 13, and negative electrode 12 of the wound electrode assembly are wound to form the assembly. A comparison of Figures 1-2 and 3 shows that, with the same casing volume for a single secondary battery cell, the wound electrode assembly, due to its corners, has a lower space utilization rate within the casing compared to the stacked electrode assembly 10.

[0085] Furthermore, considering the differences in processing between the stacked electrode assembly 10 and the wound electrode assembly, all four edges of the sheet-like electrodes used in the stacked electrode assembly 10 need to be trimmed, while only two edges of the long sheet-like electrodes in the wound electrode assembly need to be trimmed. Due to process limitations, burrs are inevitably generated during the electrode trimming process, and the burr problem at the edges of the electrodes in the stacked electrode assembly 10 is more serious. Burrs may puncture the separator 13 during the cycling process of the secondary battery cell 20, causing a short circuit between the positive and negative electrodes, and thus leading to more serious safety issues.

[0086] Lithium-containing transition metal oxides offer high specific capacity as positive electrode active materials, but suffer from poor thermal stability. At high temperatures, they are prone to side reactions with the electrolyte, generating large amounts of gas and causing rapid capacity decay in secondary battery cells, which is detrimental to their safety performance. Lithium-containing transition metal phosphates, on the other hand, exhibit good thermal stability, but their specific capacity is lower than that of lithium-containing transition metal oxides.

[0087] Based on this, in this embodiment, lithium-containing transition metal phosphates and lithium-containing transition metal oxides are selected as the positive electrode active materials, and a stacked electrode assembly 10 is adopted. With a fixed volume of the secondary battery cell, more active material can be accommodated inside the cell, improving the space utilization rate and thus increasing the energy density. Furthermore, given that the positive electrode active materials include lithium-containing transition metal phosphates and lithium-containing transition metal oxides, by using a separator 13 with a thickness of 8μm-21μm, the risk of burrs from the electrode plates in the stacked electrode assembly 10 puncturing the separator 13 during the cycling process of the secondary battery cell can be reduced. Therefore, this solution enables the secondary battery cell to possess both high energy density and good safety performance.

[0088] In one embodiment, the mass content m1 of lithium transition metal phosphate, based on the total mass of the positive electrode active material, satisfies: 40wt% ≤ m1 ≤ 70wt%.

[0089] Specifically, m1 can be 40wt%, 42wt%, 44wt%, 45wt%, 46wt%, 48wt%, 50wt%, 52wt%, 54wt%, 56wt%, 58wt%, 60wt%, 62wt%, 64wt%, 66wt%, 68wt%, 70wt%, or a value within the range obtained by any combination of the above two values.

[0090] Lithium-containing phosphates exhibit good thermal stability. When the positive electrode active material includes both lithium-containing phosphates and lithium-containing transition metal oxides, controlling the lithium-containing phosphate content within the aforementioned range can further improve the energy density of the secondary battery while maintaining high safety. This is because lithium-containing transition metal oxides generally have lower thermal stability than lithium-containing phosphates and are prone to side reactions with the electrolyte at high temperatures, which may affect the safety performance of individual secondary battery cells.

[0091] In one embodiment, the separator 13 includes a base film and a coating disposed on at least one side of the base film, wherein the thickness h1 of the coating on one side satisfies: 3μm≤h1≤6μm.

[0092] Specifically, h1 can be 3μm, 4μm, 5μm, 6μm, or a value within the range obtained by any combination of the above two values.

[0093] The base film of the separator can be made of at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The base film can be a single-layer film or a multi-layer composite film; there are no particular restrictions. When the base film is a multi-layer composite film, the materials of each layer can be the same or different; there are no particular restrictions. The coating of the separator can serve as heat resistance and / or adhesion.

[0094] In one embodiment, the thickness of the base film is typically in the range of 5 μm to 9 μm. For example, the thickness of the base film is 5 μm, 6 μm, 7 μm, 8 μm, or 9 μm.

[0095] The thickness of the coating affects both the mechanical properties of the separator 13 and its wetting rate with the electrolyte. A thicker coating results in a thicker separator 13, increasing its mechanical strength and making it less susceptible to puncture by burrs or lithium dendrites on the electrode. However, a thicker coating also slows down the electrolyte wetting rate, affecting lithium-ion transport efficiency. During the cycling process of the secondary battery cell, this may exacerbate internal polarization, leading to lithium plating and negatively impacting the energy density of the secondary battery cell. Therefore, in this embodiment, by further controlling the coating thickness within the range of 3μm-6μm within the aforementioned positive electrode active material system, the separator 13 can possess good mechanical strength and wettability, resulting in high energy density and good safety performance for the secondary battery cell.

[0096] In one embodiment, the coating comprises heat-resistant particles, which include at least one of inorganic particles and organic particles.

[0097] Specifically, inorganic particles may include boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon oxides, tin dioxide, titanium oxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, hafnium dioxide, cerium oxide, zirconium titanate, barium titanate, magnesium fluoride, aluminum hydroxide, barium oxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, calcium fluoride, barium fluoride, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, bentonite, hydropyrite, Pb(Zr,Ti)O3 (abbreviated as PZT), Pb1-mLamZr1-nTinO3 (abbreviated as PLZT, 0 < m < 1, 0 < n < 1), Pb(Mg3Nb) 2 / 3 The organic particles may be selected from one or more of PbTiO3 (abbreviated as PMN-PT) and their respective modified inorganic particles. Optionally, the modification of each inorganic particle may be chemical modification and / or physical modification. The organic particles may include at least one of thermoplastic resin polymers, thermosetting resin polymers, or crosslinked polymers.

[0098] Preferably, the coating includes inorganic particles, including at least one of alumina, silicon oxide, titanium oxide, and barium titanate. By selecting these inorganic components as the coating, it helps to improve the coating's support for the base film, reduce the risk of the base film shrinking due to heat during the cycling of the secondary battery cell, and further improve the situation where electrode burrs puncture the separator 13, thereby enhancing the safety performance of the secondary battery cell.

[0099] For example, a composite isolation membrane with a bulk layer can be obtained by applying a ceramic coating (also known as CCS treatment) to the base membrane.

[0100] Furthermore, when both sides of the base film have coatings, the wettability, thermal stability, and safety performance of the separator 13 are all superior to those of the separator 13 with a coating on only one side, which can further improve the safety performance of the secondary battery cell.

[0101] In one embodiment, the coating includes adhesive particles, which include: polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylonitrile, polyethylene oxide, copolymers of different fluorinated alkenyl monomer units, copolymers of fluorinated alkenyl monomer units and vinyl monomer units, copolymers of fluorinated alkenyl monomer units and acrylic monomer units, copolymers of fluorinated alkenyl monomer units and acrylate monomer units, and one or more of the modified compounds of the above homopolymers or copolymers.

[0102] In one embodiment, the stacked electrode assembly 10 includes a plurality of positive electrode sheets 11 and a plurality of negative electrode sheets 12, which are alternately stacked along the thickness direction. In this type of stacked electrode assembly 10, the single-sided loading 'a' of binder particles on the separator 13 satisfies: 0.5 mg / 1540.25 mm. 2 ≤a≤1.2mg / 1540.25mm 2 Optionally, 0.6 mg / 1540.25 mm 2 ≤a≤0.8mg / 1540.25mm 2 For example, a = 0.7 mg / 1540.25 mm 2 .

[0103] Given that the positive electrode active material includes lithium-containing transition metal phosphates and lithium-containing transition metal oxides, this type of stacked electrode assembly 10 has a relatively higher space utilization rate within the casing of the secondary battery cell, which helps to further improve the energy density of the secondary battery cell. However, during the cycling process of the secondary battery cell, this stacked electrode assembly 10 has a higher risk of slippage between the electrodes due to the expansion and contraction of the electrodes, which can easily lead to local lithium plating in the secondary battery cell. Therefore, by controlling the loading of binder particles on the separator 13 to 0.5 mg / 1540.25 mm... 2 -1.2mg / 1540.25mm 2 Within a specific range, the adhesion between the separator 13 and the electrode sheet can be improved, thereby enhancing the structural stability of the stacked electrode assembly 10 and thus improving the safety performance of the secondary battery cell.

[0104] Figures 4 and 5 are schematic structural diagrams of a secondary battery cell 20 according to this application.

[0105] As shown in Figures 4-5, in one embodiment, the secondary battery cell 20 includes a housing 21, and the stacked electrode assembly 10 is housed in the housing 21. The housing 21 includes a first wall 211, and the electrode terminals 22 are disposed on the first wall 211.

[0106] More specifically, the outer casing 21 may include a housing 212 and an end cap 213. The housing 212 has an internal cavity with an opening 2121, meaning the housing 212 is a hollow structure open at one end. The end cap 213 covers the opening 2121 of the housing 212 and forms a sealed connection to create a sealed space for accommodating the stacked electrode assembly 10 and the electrolyte. Optionally, the first wall 211 for mounting the electrode terminal 22 may be the end cap 213 or one of the multiple walls of the housing 212. For example, in Figures 4 and 5, the first wall 211 is the end cap 213 of the housing 21. Of course, in other embodiments, the first wall 211 may also be the bottom wall of the housing 212 opposite to the end cap 213 in the thickness direction X, or a side wall adjacent to and abutting against the end cap 213.

[0107] The housing 212 can be of various shapes, such as a cube or a cuboid. The shape of the housing 212 can be determined according to the specific shape of the stacked electrode assembly 10. For example, if the stacked electrode assembly 10 is a cuboid structure, then the housing 212 can be a cuboid structure. Of course, the end cap 213 can also be of various structures, such as a plate-like structure or a hollow structure with one end open. For example, in Figures 4 and 5, the housing 212 is a cuboid structure. It should be understood that the outer shell 21 is not limited to the aforementioned structures. The outer shell 21 can also be other structures. For example, the outer shell 21 includes a housing 212 and two end caps 213. The housing 212 is a hollow structure with openings 2121 on both sides opposite to each other. One end cap 213 is fitted onto one opening 2121 of the housing 212 to form a sealed connection, thereby forming a sealed space for accommodating the stacked electrode assembly 10 and the electrolyte.

[0108] Figure 6 is a partial schematic diagram of a secondary battery cell 20 in the region of electrode terminal 22 according to this application.

[0109] Referring to Figures 4-6, in one embodiment, the stacked electrode assembly 10 includes a body 101 and a tab 102, with the tab 102 connected to the end of the body 101 facing the first wall 211. The secondary battery cell 20 includes a current collector 24 disposed between the first wall 211 and the body 101. The current collector 24 includes a first connecting portion 241 and a second connecting portion 242 connected to each other. The first connecting portion 241 is connected to the electrode terminal 22, and the second connecting portion 242 is connected to the tab 102. Along the thickness direction X of the first wall 211, the thickness of the first connecting portion 241 is greater than the thickness of the second connecting portion 242.

[0110] Specifically, the main body 101 of the stacked electrode assembly 10 is the primary region where the electrochemical reaction occurs within the secondary battery cell 20. The main body 101 is formed by the region of the positive electrode 11 coated with positive active material, the separator, and the region of the negative electrode 12 coated with negative active material, which are wound or stacked together. The tabs 102 are used for outputting or inputting the positive or negative electrode of the stacked electrode assembly 10, and are used to connect to the electrode terminals 22 to achieve electrical connection between the electrode assembly 10 and the electrode terminals 22. It should be noted that the tabs 102 of the stacked electrode assembly 10 are either components formed by stacking and connecting regions of the positive electrode 11 that are not coated with positive active material, or components formed by stacking and connecting regions of the negative electrode 12 that are not coated with negative active material. If the tab 102 is used to output the positive electrode of the stacked electrode assembly 10, then the tab 102 is a component formed by stacking and connecting the regions of the positive electrode sheet 11 that are not coated with positive active material; if the tab 102 is used to output the negative electrode of the stacked electrode assembly 10, then the tab 102 is a component formed by stacking and connecting the regions of the negative electrode sheet 12 that are not coated with negative active material. For example, the tab 102 is connected to one end of the body 101 facing the end cap 213 in the thickness direction X.

[0111] The stacked electrode assembly 10 housed within the housing 21 can be one or more. For example, in FIG5, the housing 21 of the secondary battery cell 20 is provided with two stacked electrode assemblies 10, which are stacked along their thickness direction. That is, the two stacked electrode assemblies 10 are stacked along the thickness direction of the secondary battery cell 20. Of course, in other embodiments, the stacked electrode assembly 10 housed within the housing 21 can be one, three, four, five, six, seven, or eight, etc.

[0112] Electrode terminal 22 is a component used to output or input electrical energy to the secondary battery cell 20. For example, the electrode terminal 22 can be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy. One end of the electrode terminal 22 facing the stacked electrode assembly 10 is connected to the current collector 24, and the other end of the electrode terminal 22 away from the stacked electrode assembly 10 is connected to the current collector to realize the input or output of electrical energy to the secondary battery cell 20. A first through hole 2111 is provided on the end cover 213, extending through both sides of the end cover 213 along its thickness direction X. The electrode terminal 22 passes through the first through hole 2111 to mount the electrode terminal 22 onto the end cover 213, with both ends of the electrode terminal 22 extending out of the first through hole 2111. The electrode terminal 22 is insulated from the end cover 213, meaning no electrical connection is formed between the electrode terminal 22 and the end cover 213. The secondary battery cell 20 may also include an insulating member 26 to insulate and isolate the end cap 213 and the electrode terminal 22. The secondary battery cell 20 may also include a sealing member 27 to seal the gap between the electrode terminal 22 and the wall surface of the first through hole 2111.

[0113] In Figures 4 and 5, the secondary battery cell 20 includes two electrode terminals 22. Correspondingly, each stacked electrode assembly 10 has two tabs 102, and the polarities of the two tabs 102 are opposite. The two electrode terminals 22 are electrically connected to the two tabs 102 of the stacked electrode assembly 10, respectively, to realize the input or output of the positive and negative electrodes of the secondary battery cell 20.

[0114] The current collector 24 serves to connect the electrode terminal 22 and the tab 102 to achieve an electrical connection between the stacked electrode assembly 10 and the electrode terminal 22. For example, the current collector 24 can be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy. The connection structure between the current collector 24 and the electrode terminal 22 can be various, such as welding, abutment, or bonding. Similarly, the connection structure between the current collector 24 and the tab 102 can also be various, such as welding or abutment. There are two electrode terminals 22 and two current collectors 24, arranged at intervals along the first direction Z. Each electrode terminal 22 is connected to the stacked electrode assembly 10 through one current collector 24 to output the positive and negative terminals of the secondary battery cell 20. As shown in Figure 6, the current collector 24 may also include a bending portion 243, through which the first connecting portion 241 and the second connecting portion 242 are connected.

[0115] In this embodiment, the thickness of the area of ​​the current collector 24 used to connect the electrode terminal 22 is greater than the thickness of the area of ​​the current collector 24 used to connect the tab 102. Since the thickness requirement of the area where the current collector 24 connects to the tab 102 is less than the thickness requirement of the area where the current collector 24 connects to the electrode terminal 22, the thickness of the current collector 24 can be effectively optimized while still enabling it to connect the electrode terminal 22 and the tab 102. This reduces the overall weight of the current collector 24 and saves space, thereby optimizing the weight and internal space utilization of the secondary battery cell 20 and improving its energy density.

[0116] In one embodiment, along the thickness direction X of the current collector 24, the thickness D1 of the first connecting portion 241 satisfies: 0.5mm≤D1≤1.2mm; and the thickness D2 of the second connecting portion 242 satisfies: 0.3mm≤D2≤1mm.

[0117] For example, D1 can be 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.15mm, or 1.2mm, or a value within the range obtained by any combination of the above two values. D2 can be 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 0.95mm, or 1mm, or a value within the range obtained by any combination of the above two values.

[0118] In this embodiment, by setting the thickness of the first connecting portion 241 and the thickness of the second connecting portion 242 within a suitable range, the structural strength of the first connecting portion 241 and the second connecting portion 242 can be improved. This ensures that the first connecting portion 241 and the second connecting portion 242 have sufficient thickness to connect with the electrode terminal 22 and the tab 102, which is beneficial to improving the connection stability and reliability between the first connecting portion 241 and the second connecting portion 242 and the electrode terminal 22 and the tab 102, and reducing the phenomenon of insufficient overcurrent between the current collector 24 and the electrode terminal 22, and between the current collector 24 and the tab 102. On the other hand, it can reduce the connection difficulty between the first connecting portion 241 and the electrode terminal 22, and between the second connecting portion 242 and the tab 102, and can reduce the space occupied by the current collector 24 in the housing 21, which is beneficial to improving the energy density of the secondary battery cell 20.

[0119] In one embodiment, 0.1mm ≤ D1 - D2 ≤ 0.9mm.

[0120] Specifically, it can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, or a value within the range obtained by any combination of the above two values.

[0121] In this embodiment, by setting the thickness D1 of the first connecting portion 241 to be greater than or equal to 0.1 mm and less than or equal to 0.9 mm than the thickness D2 of the second connecting portion 242, the thickness of the current collector 24 in the area connected to the tab 102 is further reduced. This further optimizes the thickness of the current collector 24, thereby reducing the overall weight of the current collector 24 and saving the space occupied by the current collector 24. This is beneficial for further reducing the weight of the secondary battery cell 20 and improving the internal space utilization of the secondary battery cell 20, thereby increasing the energy density of the secondary battery cell 20.

[0122] In some other implementations, the current collector 24 can be omitted, and the tab 102 can be directly connected to the electrode terminal 22. However, this method is extremely difficult to manufacture, and this application will not elaborate on it.

[0123] Figure 7 is an exploded view of a partial structure of a secondary battery cell 20 according to this application. Figure 8 is a cross-sectional view of a partial structure of a secondary battery cell 20 according to this application, and Figure 9 is a schematic diagram of a local area in Figure 8.

[0124] As shown in Figures 7-9, in one embodiment, the first wall 211 includes a first through hole 2111, and the electrode terminal 22 includes a main body 221 and a stepped portion 222. The stepped portion 222 protrudes from the outer peripheral surface of the main body 221 and is located on the side of the first wall 211 facing the outside of the secondary battery cell 20. The secondary battery cell 20 includes a fixing member 28, which includes a second through hole 281 through which the main body 221 passes. In the thickness direction of the first wall 211, at least a portion of the fixing member 28 is located between the first wall 211 and the stepped portion 222 and abuts against the stepped portion 222. The main body 221 has a first end face 2211 facing the outside of the secondary battery cell 20, and the fixing member 28 has a second end face 282 facing the outside of the secondary battery cell 20, with the first end face 2211 extending beyond the second end face 282.

[0125] Specifically, the exterior of the secondary battery cell 20 refers to the portion of the secondary battery cell 20 outside the housing 21. The first end face 2211 extends beyond the second end face 282, meaning that on the outside of the secondary battery cell 20, in the thickness direction of the first wall 211, the second end face 282 is located between the first end face 2211 and the outer surface of the first wall 211. In other words, the surface furthest from the outer surface of the first wall 211 is the first end face 2211 of the electrode terminal 22.

[0126] The outer peripheral surface of the main body portion 221 may refer to the outer peripheral surface of a cylinder or the peripheral surface of a prism that connects the top and bottom surfaces of the prism. Taking the main body portion 221 as a quadrangular prism as an example, the main body portion 221 includes a top surface, a bottom surface, and four side surfaces. The four side surfaces are sequentially connected and surround the top surface. The two ends of the four side surfaces in the direction from the top surface to the bottom surface are respectively connected to the top surface and the bottom surface. The above four side surfaces refer to the outer peripheral surface of the main body portion 221. In some embodiments, a first groove 2212 is provided on the first end surface 2211, and the side surface of the first groove 2212 may also be referred to as the outer peripheral surface of the main body portion 221. In this embodiment, the main body portion 221 is in a shape similar to a "convex" character. In some embodiments, the stepped portion 222 has a third end surface 2221 facing away from the first wall 211.

[0127] The outer contour of the fixing member 28 may include, but is not limited to, a circle, an ellipse, a polygon, a semi - circle, etc. The fixing member 28 is made of a metal material, for example, made of aluminum, copper, iron, steel, alloy or composite metal. The stepped portion 222 may be continuously distributed along the circumferential direction of the main body portion 221, that is, in a ring shape. It may also be provided in segments along the circumferential direction of the main body portion 221, that is, divided into multiple parts, and at least one part of which abuts against the fixing member 28. The first through - hole 2111 and the second through - hole 281 may be a through - hole or a stepped through - hole. In the embodiment where the first through - hole 2111 and the second through - hole 281 are stepped through - holes, the cross - section of the stepped through - hole may include at least one straight segment and / or at least one oblique segment and / or at least one arc segment.

[0128] As mentioned above, the lithium - containing transition metal as the cathode active material has a high specific capacity, but poor thermal stability, and is prone to side reactions with the electrolyte at high temperatures, which is not conducive to the safety performance of the secondary battery cell 20. And the lithium - containing transition metal phosphate has good thermal stability. In addition, considering that in some cases, the electrode terminal 22 of the secondary battery cell 20 is riveted to the wall portion of the outer shell 21 through a riveting block that wraps the end portion of the electrode terminal 22. In the direction of the wall portion of the outer shell 21, the surface of the riveting block away from the wall portion of the outer shell 21 will exceed the outer end surface of the electrode terminal 22. This design is to give additional protection and support to the electrode terminal to reduce the risk of the electrode terminal loosening. At the same time, the electric energy of the secondary battery cell 20 can be transmitted to the inside of the secondary battery cell 20 through the riveting block.

[0129] In this embodiment, in the thickness direction of the first wall 211, the surface of the secondary battery cell 20 with the maximum height exceeding the outer surface of the first wall 211 is the first end surface 2211. When using electrode terminals 22 of the same specification, the height of the secondary battery cell 20 exceeding the first wall 211 can be correspondingly reduced, increasing the proportion of the space inside the outer shell 21 of the secondary battery cell 20 in the total space of the secondary battery cell 20. Furthermore, the energy density of the secondary battery cell 20 is increased.

[0130] In one embodiment, the electrode terminal 22 further includes a limiting portion 223, which protrudes from the outer peripheral surface of the main body portion 221 and is located inside the first wall 211. The limiting portion 223 is used to restrict the electrode terminal 22 from moving to the outside of the housing 21.

[0131] Exemplarily, the insulating member 26 includes a body portion 261 and a first extension portion 262. The body portion 261 is located between the fixing member 28 and the first wall 211, and the body portion 261 is provided with a third through hole 2611 through which the power supply terminal 22 passes. The first extension portion 262 is located on the outer periphery of the fixing member 28 and surrounds the edge of the body portion 261. The sealing member 27 is at least partially located between the first wall 211 and the limiting portion 223.

[0132] In one embodiment, in the thickness direction of the first wall 211, the height difference H between the first end face 2211 and the second end face 282 satisfies: 0.5mm≤H≤1.5mm.

[0133] Specifically, H can be 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, or 1.5mm, or a value within the range obtained by any combination of the above two values. By controlling H within a suitable range, the energy density of the secondary battery cell 20 can be improved while ensuring good connection stability between the first end face 2211 and the second end face 282.

[0134] In one embodiment, the step portion 222 protrudes from the outer peripheral surface of the main body portion 221 by a dimension W1 that satisfies: 0.1mm≤W1≤5mm.

[0135] Specifically, W1 can be 0.1mm, 0.2mm, 0.4mm, 0.6mm, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3mm, 3.2mm, 3.4mm, 3.6mm, 3.8mm, 4mm, 4.2mm, 4.4mm, 4.6mm, 4.8mm, 5mm, or a value within the range obtained by any combination of the above two values. By controlling the size of the step portion 222 protruding from the outer peripheral surface of the main body portion 221 within a suitable range, it is beneficial to increase the contact area between the step portion 222 and the fastener 28, thereby improving the connection strength between the step portion 222 and the fastener 28.

[0136] In one embodiment, the positive electrode 11 includes a conductive agent, which includes carbon nanotubes, and the diameter l of the carbon nanotubes satisfies: 7nm≤l≤13nm.

[0137] Specifically, l can be 7nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm, or a value within the range obtained by any combination of the above two values. The conductive agent directly affects the internal resistance, rate performance, thermal stability, energy density, and cycle performance of the secondary battery cell 20. Compared to conductive agents such as conductive carbon black and Ketjen black, carbon nanotubes have a linear contact with the positive electrode active material, forming a conductive network between the positive electrode active material, resulting in higher conductivity. This reduces polarization during the cycling process of the secondary battery cell, improving the rate performance and cycle performance of the secondary battery cell 20. Furthermore, the diameter of the carbon nanotubes directly affects their stability; a larger diameter results in greater stability but lower conductivity. Therefore, in this embodiment, selecting carbon nanotubes with a diameter within a suitable range as the conductive agent helps improve lithium-ion kinetics at the positive electrode 11, thereby improving the rate performance and cycle performance of the secondary battery cell.

[0138] In one embodiment, the average particle size D1 of the lithium transition metal oxide particles satisfies: 2μm≤D1≤5μm.

[0139] Specifically, D1 can be 2μm, 3μm, 4μm, 5μm, or a value within the range obtained by any combination of the above two values. Lithium-containing transition metal oxides with an average particle size range of 2μm-5μm exhibit better structural stability and contribute to improving the powder compaction density of the positive electrode sheet. This further enhances the energy density and safety performance of the secondary battery cell 20.

[0140] According to this application, the smaller the average particle size of the lithium transition metal oxide, the better its structural stability, which is more beneficial to the safety performance and energy density of the secondary battery cell 20. However, if the average particle size of the lithium transition metal oxide is too small, side reactions with the electrolyte may increase, which is detrimental to the cycle life of the secondary battery cell 20. Therefore, this embodiment, by controlling the average particle size of the primary particles containing lithium transition metal oxide within a suitable range, enables the secondary battery cell 20 to achieve a balance between high energy density, safety performance, and good cycle performance.

[0141] In one embodiment, the lithium-containing transition metal oxide includes: Li 1+c [Ni x Co y Mn z M d ]O 2-eWherein, M includes at least one of Zr, Al, Ti, Sb, Nb, Te, Mg, B, Ca, V, Ta or Sr, 0.2≥c≥-0.2, 0.95≥x≥0.6, 0.2≥y≥0.05, 0.3>z>0, 0.3>d≥0, 0.5≥e≥0.

[0142] Specifically, lithium-containing transition metal oxides can be doped with some M element. Doping with M element helps to improve the structural stability of lithium-containing transition metal oxides, thereby helping to improve the safety performance of secondary battery cell 20.

[0143] In one embodiment, the positive electrode 11 satisfies at least one of the following conditions: (1) the compaction density ρ1 of the positive electrode 11 satisfies: 2.5 g / cm³ 3 ≤ρ1≤2.9g / cm 3 (2) The single-sided coating weight CW1 of the positive electrode film layer satisfies: 190 g / m 2 ≤CW1≤230g / m 2 (3) The thickness h1 of the positive current collector satisfies: 10μm≤h1≤13μm.

[0144] Specifically, ρ1 can be 2.5 g / m 2 2.6g / cm 3 2.7g / cm 3 2.8g / cm 3 2.9g / cm 3 Or, its value is within the range obtained by combining any two of the above values. CW1 can be 190g / m 2 195g / m 2 200g / m 2 205g / m 2 210g / m 2 215g / m 2 220g / m 2 225g / m 2 230g / m 2 h1 can be 10μm, 10.2μm, 10.4μm, 10.6μm, 10.8μm, 11μm, 11.2μm, 11.4μm, 11.6μm, 11.8μm, 12μm, 12.2μm, 12.4μm, 12.6μm, 12.8μm, or 13μm, or its value can be within the range obtained by any two combinations of the above values.

[0145] According to this application, the coating weight of the film layer on the electrode and the compaction density of the electrode have a certain impact on the lithium-ion kinetics during the cycling process of the secondary battery cell 20. The greater the coating weight of the film layer and the greater the compaction density of the electrode, the worse the lithium-ion kinetics. Insufficient lithium-ion kinetics may lead to polarization in the secondary battery cell 20, resulting in lithium plating and affecting the safety performance of the secondary battery cell 20. However, if the coating weight of the film layer is too small or the compaction density of the electrode is too small, it is also detrimental to the energy density of the secondary battery cell 20. The aforementioned electrode can be a positive electrode or a negative electrode. The aforementioned film layer can be a positive electrode film or a negative electrode film.

[0146] According to this application, a thinner current collector is more conducive to reducing the thickness of the electrode, thereby increasing the energy density of the secondary battery cell 20. However, an excessively thin current collector is detrimental to the mechanical strength of the electrode and may break during the processing or use of the secondary battery cell 20. The aforementioned current collector can be either a positive electrode current collector or a negative electrode current collector.

[0147] Therefore, by controlling the coating weight of the positive electrode film, the compaction density of the positive electrode sheet 11, and the thickness of the positive electrode current collector within a suitable range, this embodiment enables the secondary battery cell 20 to achieve both high energy density and good safety performance.

[0148] In one embodiment, the negative electrode 12 satisfies at least one of the following conditions: (4) the compaction density ρ2 of the negative electrode 12 satisfies: 1.3 g / cm³ 3 ≤ρ2≤1.55g / cm 3 (5) The single-sided coating weight CW2 of the negative electrode film layer satisfies: 90 g / m 2 ≤CW2≤110g / m 2 (6) The thickness h2 of the negative electrode current collector satisfies: 4μm≤h2≤6μm.

[0149] Specifically, ρ2 can be 1.3 g / cm³. 3 1.32g / cm 3 1.34 g / cm 3 1.35g / cm 3 1.36 g / cm 3 1.38g / cm 3 1.4g / cm 3 1.42g / cm 3 1.44 g / cm 3 1.46 g / cm 3 1.48g / cm 3 1.5g / cm 3 Or, its value is within the range obtained by combining any two of the above values. CW2 can be 90g / m2 92g / m 2 94g / m 2 96g / m 2 98g / m 2 100g / m 2 102g / m 2 104g / m 2 106g / m 2 108g / m 2 110g / m 2 h2 can be 4μm, 4.2μm, 4.4μm, 4.6μm, 4.8μm, 5μm, 5.2μm, 5.4μm, 5.6μm, 5.8μm, or 6μm, or its value can be within the range obtained by any combination of the two values ​​mentioned above.

[0150] Similar to the positive electrode 11, in this embodiment, by controlling the coating weight of the negative electrode film, the compaction density of the negative electrode 12, and the thickness of the negative electrode current collector within a suitable range, the secondary battery cell 20 can achieve both high energy density and good safety performance.

[0151] In one embodiment, the negative electrode active material comprises graphite.

[0152] In one embodiment, the average volumetric particle size Dv50 of graphite satisfies: 10μm≤Dv50≤14μm.

[0153] Specifically, Dv50 can be 10μm, 10.2μm, 10.4μm, 10.6μm, 10.8μm, 11μm, 11.2μm, 11.4μm, 11.6μm, 11.8μm, 12μm, 12.2μm, 12.4μm, 12.6μm, 12.8μm, 13μm, 13.2μm, 13.4μm, 13.6μm, 13.8μm, 14μm, or a value within the range obtained by any combination of the above two values. The average volumetric particle size of graphite affects the capacity and lithium-ion kinetics of a single secondary battery cell. The smaller the average volumetric particle size of graphite, the larger the specific surface area, which can provide more active sites in the electrochemical reaction, thereby facilitating the extraction and insertion of lithium ions and improving the capacity and lithium-ion kinetics of the secondary battery cell 20. If the average volumetric particle size of graphite is too small, it may result in insufficient contact area between particles, increasing the internal resistance of the secondary battery cell 20 and thus affecting its cycle performance. Therefore, this embodiment, by controlling the average volumetric particle size of graphite within a suitable range, can help improve the capacity and cycle performance of the secondary battery cell 20.

[0154] In one embodiment, the secondary battery cell 20 includes an electrolyte, which includes a solvent, the solvent being a linear carbonate; based on the total mass of the electrolyte, the mass content m2 of the linear carbonate satisfies 40wt% ≤ m2 ≤ 70wt%.

[0155] Specifically, m2 can be 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, or a value within the range obtained by any combination of the above two values. In this embodiment, by selecting a linear carboxylic acid ester as the solvent and controlling its mass content in the electrolyte within a suitable range, it is helpful to reduce the viscosity of the electrolyte, thereby helping to improve lithium-ion kinetics.

[0156] In one embodiment, the electrolyte comprises a lithium salt, including LiPF6 and LiFSI; the mass content of the lithium salt m3, based on the total mass of the electrolyte, satisfies 13wt% ≤ m3 ≤ 18wt%.

[0157] Specifically, m3 can be 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, or 18wt%, or a value within the range obtained by any combination of the above two values. In this embodiment, by selecting LiPF6 and LiFSI as lithium salts, it is helpful to improve the lithium-ion conductivity and high-temperature resistance of the electrolyte, thereby helping to improve the lithium-ion kinetics during the cycling process of the secondary battery cell 20 and improving the safety performance of the secondary battery cell 20.

[0158] In one embodiment, the molar content n of LiPF6, based on the total amount of the lithium salt, satisfies: 50% ≤ n ≤ 70%.

[0159] Specifically, it can be 50%, 55%, 60%, 65%, 70%, or a value within the range obtained by any combination of the above two values. LiPF6 has good film-forming stability. By controlling the molar content of LiPF6 within a high range, it helps to form a stable SEI film on the surface of the negative electrode 12, thereby improving the safety performance of the secondary battery cell 20.

[0160] In one embodiment, the secondary battery cell 20 includes an electrolyte, and the ionic conductivity σ of the electrolyte at 25°C satisfies: 7mS / cm≤σ≤10mS / cm.

[0161] Specifically, σ can be 7 mS / cm, 7.5 mS / cm, 8 mS / cm, 8.5 mS / cm, 9 mS / cm, 9.5 mS / cm, 10 mS / cm, or a value within the range obtained by any combination of the above two values. In this embodiment, selecting an electrolyte with high ionic conductivity helps improve lithium-ion kinetics during the cycling process of the secondary battery cell 20, helps reduce the probability of polarization in the secondary battery cell 20, and improves the safety performance of the secondary battery cell 20.

[0162] Next, taking a lithium-ion battery as a specific example, the positive electrode 11, negative electrode 12, separator 13, and electrolyte in the secondary battery cell 20 will be described in detail. It should be understood that the lithium-ion battery is only an example, and the solution provided in this application can also be applied to other types of secondary batteries, such as sodium-ion batteries, magnesium-ion batteries, and lithium-sulfur batteries.

[0163] [Negative electrode plate]

[0164] As mentioned earlier, the negative electrode 12 typically includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector. The negative electrode film layer includes a negative electrode active material.

[0165] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0166] In one embodiment, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymeric material substrate and a metal layer formed on at least one surface of the polymeric material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymeric material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0167] In one embodiment, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0168] In one embodiment, the negative electrode film layer further includes an adhesive. The adhesive may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0169] In one embodiment, the negative electrode film layer further includes a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0170] In one embodiment, the negative electrode film layer also includes other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0171] In one embodiment, the negative electrode 12 can be prepared by forming a negative electrode slurry using the components described above. For example, the negative electrode active material, conductive agent, binder, and any other components are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a negative electrode slurry. The negative electrode slurry is then coated onto a negative electrode current collector, and after drying, cold pressing, and other processes, the negative electrode 12 is obtained.

[0172] [Positive electrode plate]

[0173] As mentioned earlier, the positive electrode 11 includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including a positive electrode active material.

[0174] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0175] In one embodiment, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0176] In another embodiment, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium-containing transition metal phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites. During the charging and discharging process, Li undergoes insertion / extraction and consumption, resulting in different molar contents of Li in the positive electrode active material when the battery is discharged to different states. In the examples of positive electrode active materials in this application, the molar content of Li is the initial state of the material, i.e., the state before feeding. After charge-discharge cycles, the molar content of Li changes when the positive electrode active material is applied to the battery system. In the examples of positive electrode active materials in this application, the molar content of O is only an ideal value; lattice oxygen release causes changes in the molar content of O, and the actual molar content of O will fluctuate.

[0177] In positive electrode active materials including Li 1+c [Ni x Co y Mn z M d ]O 2-e In the example, d is 0, and the positive electrode active material includes LiNi. 0.7 Co 0.1 Mn 0.2O2. As another example, d>0, positive electrode active materials include LiNi. 0.7 Co 0.1 Mn 0.1 Al 0.1 O2.

[0178] In one embodiment, the positive electrode active material includes: LiNi 0.90 Co 0.06 Mn 0.04 O2, LiNi 0.7 Co 0.1 Mn 0.2 O2, LiNi 0.7 Co 0.2 Mn 0.1 O2 or LiNi 0.8 Co 0.1 Mn 0.1 At least one of O2.

[0179] In one embodiment, the positive electrode film layer further includes a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0180] In one embodiment, the positive electrode film layer further includes a conductive agent. As an example, the conductive agent may also include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, graphene, and carbon nanofibers.

[0181] In one embodiment, the positive electrode 11 can be prepared by forming a positive electrode slurry from the components described above. For example, the positive electrode active material, conductive agent, binder, and any other components are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry. The positive electrode slurry is then coated onto a positive electrode current collector, and after drying, cold pressing, and other processes, the positive electrode 11 is obtained.

[0182] Electrolyte

[0183] The electrolyte acts as a conductor of ions between the positive electrode 11 and the negative electrode 12. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or entirely solid.

[0184] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution comprises an electrolyte salt and a solvent. Some electrolyte solutions have already been mentioned above.

[0185] In addition to the aforementioned schemes, in some embodiments, the electrolyte salt may also be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0186] In some embodiments, the solvent may also be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0187] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0188] [Isolation membrane]

[0189] As mentioned earlier, the separator 13 includes a coating, which includes at least one of inorganic particles and organic particles.

[0190] In one embodiment, the inorganic particles may further include one or more of the following: inorganic particles that are ion-conductive but do not store ions, or inorganic particles that are capable of undergoing electrochemical reactions.

[0191] In one embodiment, inorganic particles that are ion-conductive but do not store ions may include Li3PO4, lithium titanium phosphate (Li3PO4), etc. x1 Ti y1 (PO4)3, Lithium aluminum titanium phosphate (Li) x2 Al y2 Ti z1 (PO4)3、(LiAlTiP) x3 O y3 Type glass, lithium lanthanum titanate (Li) x4 La y4 TiO3, lithium germanium thiophosphate (Li) x5 Ge y5 P z2 S w Lithium nitride (Li) x6 N y6 SiS2 type glass Li x7 Si y7 S z3 and P2S5 type glass Lix8 P y8 S z4 One or more of the following are given: 0 < x1 < 2, 0 < y1 < 3, 0 < x2 < 2, 0 < y2 < 1, 0 < z1 < 3, 0 < x3 < 4, 0 < y3 < 13, 0 < x4 < 2, 0 < y4 < 3, 0 < x5 < 4, 0 < y5 < 1, 0 < z2 < 1, 0 < w < 5, 0 < x6 < 4, 0 < y6 < 2, 0 < x7 < 3, 0 < y7 < 2, 0 < z3 < 4, 0 < x8 < 3, 0 < y8 < 3, 0 < z4 < 7. This can improve the ion conductivity of the separator.

[0192] In one embodiment, the inorganic particles capable of undergoing electrochemical reactions may include one or more of lithium-containing transition metal oxides, lithium-containing phosphates, carbon-based materials, silicon-based materials, tin-based materials, and lithium-titanium compounds.

[0193] As mentioned earlier, organic particles may include at least one of thermoplastic resin polymers, thermosetting resin polymers, or cross-linked polymers.

[0194] In one embodiment, the thermoplastic resin polymer may include one or more of the following: polycarbonate organic particles, polymethyl methacrylate organic particles, polyoxymethylene organic particles, polyamide organic particles, styrene-acrylonitrile copolymer, polyphenylene sulfide organic particles, polyetheretherketone organic particles, polyimide organic particles, polysulfone organic particles, polyethersulfone organic particles, polyphenylene sulfone organic particles, polybenzimidazole organic particles, polyamide-imide organic particles, and polyethyleneimine organic particles.

[0195] In one embodiment, the thermosetting resin polymer may include one or more of the following: phenolic resin organic particles, polymer particles containing triazine ring structural units, epoxy resin organic particles, unsaturated polyester resin organic particles, urea-formaldehyde resin organic particles, and furan resin organic particles.

[0196] In one embodiment, the crosslinked polymer may include one or more of crosslinked styrene organic particles and silicon-containing organic crosslinked resin particles.

[0197] In one embodiment, the adhesive particles may include one or more of the following: copolymers of acrylate monomer units and styrene monomer units; copolymers of acrylate monomer units and styrene monomer units; copolymers of acrylate monomer units, acrylate monomer units, and styrene monomer units; copolymers of styrene monomer units, olefin monomer units, and unsaturated nitrile monomer units; and copolymers of styrene monomer units, olefin monomer units, and unsaturated nitrile monomer units; and modified compounds of the above homopolymers or copolymers.

[0198] In one embodiment, the adhesive particles may include one or more of the following: butyl acrylate-styrene copolymer, butyl methacrylate-isooctyl methacrylate copolymer, isooctyl methacrylate-styrene copolymer, methacrylate-methacrylate-styrene copolymer, methyl acrylate-isooctyl methacrylate-styrene copolymer, butyl acrylate-isooctyl methacrylate-styrene copolymer, butyl acrylate-isooctyl methacrylate-styrene copolymer, butyl methacrylate-isooctyl methacrylate-styrene copolymer, butyl methacrylate-isooctyl methacrylate-styrene copolymer, styrene-acrylonitrile copolymer, styrene-butadiene-acrylonitrile copolymer, methyl acrylate-styrene-acrylonitrile copolymer, isooctyl methacrylate-styrene-acrylonitrile copolymer, styrene-vinyl acetate copolymer, styrene-vinyl acetate-pyrrolidone copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene-acrylic acid copolymer, vinylidene fluoride-hexafluoropropylene-acrylate copolymer, and a modifying compound of the above copolymers.

[0199] In one embodiment, the coating may further include a dispersant, such as one or more of the following: alkylphenol polyoxyethylene ethers, polyacrylic acid dispersants, and cellulose dispersants. As an example, the dispersant may include, but is not limited to, sodium carboxymethyl cellulose, sodium polyacrylate, and ammonium polyacrylate.

[0200] [Rechargeable Battery]

[0201] This application provides a secondary battery, including the secondary battery cell 20 described in the above embodiments. The secondary battery can be a single physical module comprising one or more secondary battery cells 20 to provide higher voltage and capacity. When there are multiple secondary battery cells 20, the multiple secondary battery cells 20 are connected in series, parallel, or in a mixed configuration via a busbar.

[0202] In some embodiments, the secondary battery can be a battery pack, which includes a housing and a secondary battery cell 20, wherein the secondary battery cell 20 or battery module is housed in the housing.

[0203] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0204] In some embodiments, the secondary battery may be located in the energy storage device. The energy storage device includes energy storage containers, energy storage cabinets, etc.

[0205] Figure 10 is a schematic diagram of a secondary battery according to an embodiment of this application. As shown in Figure 10, the secondary battery 30 may include multiple secondary battery cells 20 to meet different power usage needs.

[0206] The secondary battery 30 may also include a housing with a hollow interior, housing multiple secondary battery cells 20. For example, multiple secondary battery cells 20 may be connected in parallel, series, or a combination thereof and then placed inside the housing. The housing may include a first housing portion 301 and a second housing portion 302, which are fitted together to form the housing. The shapes of the first housing portion 301 and the second housing portion 302 may be determined by the shape of the components housed inside, for example, by the shape of the combination of the multiple secondary battery cells 20 housed inside. At least one of the first housing portion 301 and the second housing portion 302 may have an opening. For example, as shown in FIG10, only one of the first housing portion 301 and the second housing portion 302 may be a hollow cuboid with an opening, while the other may be plate-shaped to cover the opening. Taking the second box section 302 as a hollow cuboid with an opening, and the first box section 301 as a plate as an example, the first box section 301 covers the opening of the second box section 302 to form a box with a closed chamber, which can be used to accommodate multiple secondary battery cells 20.

[0207] For example, unlike that shown in Figure 10, the first housing portion 301 and the second housing portion 302 can both be hollow cuboids with one open side each. The openings of the first housing portion 301 and the second housing portion 302 are opposite to each other, and the first housing portion 301 and the second housing portion 302 are interlocked to form a housing with a closed chamber. This chamber can be used to accommodate multiple secondary battery cells 20. The multiple secondary battery cells 20 are connected in parallel, series, or mixed and placed in the housing formed by the interlocking of the first housing portion 301 and the second housing portion 302.

[0208] In some embodiments, the secondary battery 30 may further include other components. For example, the secondary battery 30 may further include a busbar component, which can be used to realize electrical connections between multiple secondary battery cells 20, such as in parallel, series, or mixed connections. Specifically, the busbar component can realize electrical connections between secondary battery cells 20 by connecting to the electrode terminals of the secondary battery cells 20; or, the busbar component can also realize electrical connections between secondary battery cells 20 by connecting to other components of the secondary battery cells 20. The busbar component can be fixed to corresponding components of the secondary battery cells 20 by welding, for example, by welding to electrode terminals, sealing structures, or housings, etc., and the embodiments of this application are not limited thereto.

[0209] The secondary battery cells 20 can be directly assembled into secondary battery 30, or they can be first assembled into battery modules, and then multiple battery modules can be assembled into battery 30.

[0210] [Electrical appliances]

[0211] This application provides an electrical device including the secondary battery described in the above embodiments.

[0212] Electrical devices can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical devices.

[0213] This application provides an electrical device, which is a vehicle.

[0214] The vehicle can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. The vehicle's interior can house a motor, a controller, and a secondary battery 30. The controller is used to control the secondary battery 30 to supply power to the motor. For example, the secondary battery 30 can be located at the bottom, front, or rear of the vehicle. The battery 30 can be used to power the vehicle; for example, the secondary battery 30 can serve as the vehicle's operating power source for the vehicle's electrical system, such as for the power needs of starting, navigation, and operation. In another embodiment of this application, the secondary battery 30 can not only serve as the vehicle's operating power source but also as the vehicle's drive power source, replacing or partially replacing gasoline or natural gas to provide driving power to the vehicle.

[0215] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0216] [Examples and Comparative Examples]

[0217] Example 1

[0218] (1) Preparation of negative electrode sheet

[0219] The negative electrode active materials graphite, sodium carboxymethyl cellulose, styrene-butadiene rubber and acetylene black were mixed in a mass ratio of 96:1:1:2, deionized water was added, and the mixture was stirred evenly in a mixer. The slurry was then coated onto an 8-micron thick copper foil, dried in an oven at 120°C, cold-pressed, and slit to obtain the negative electrode sheet.

[0220] (2) Preparation of positive electrode sheet

[0221] The positive electrode active material contains lithium transition metal phosphate LiMn 0.6 Fe 0.4 O4 and lithium-containing layered metal oxides LiNi 0.65 Co 0.15 Mn 0.2 O2, polyvinylidene fluoride (PVDF) binder, acetylene black conductive agent, and carbon nanotubes are mixed in a mass ratio of 96.5:2:1:0.5 (where the mass ratio of lithium transition metal phosphate and lithium layered metal oxide is 1:1). NMP is added, and the mixture is stirred evenly in a mixer. The slurry is then coated onto a 12-micron thick aluminum foil, dried in an oven, cold-pressed, and slit to obtain the positive electrode sheet.

[0222] (3) Preparation of secondary battery cells

[0223] Multiple positive electrode sheets, a separator, and multiple negative electrode sheets are stacked sequentially to obtain a stacked electrode assembly. This stacked electrode assembly is then placed in a housing, an electrolyte is injected, and the assembly is sealed to obtain a single secondary battery cell. The electrolyte is a 1M solution using ethylene carbonate (EC) and diethyl carbonate (DEC) as solvents (volume ratio 1:2) and lithium salts (LiPF6 and LiFSI, molar ratio 2:1). The housing dimensions are 50mm × 194mm × 110mm.

[0224] In the secondary battery cell of Example 1, the mass content of lithium transition metal phosphate is m1 = 50%, the average particle size of lithium transition metal oxide particles is D1 = 4 μm, and the single-sided coating weight of the positive electrode is CW1 = 215 g / m. 2 The coating weight of the negative electrode film is CW2 = 99 g / m. 2 The separator has a thickness h = 13 μm and is a double-sided coated separator. The base film thickness is 5 μm, and the coating thickness h1 = 4 μm. The inorganic particles in the coating include alumina, and the binder includes PVDF. The PVDF loading on one side of the separator is a = 0.75 mg / 1540.25 mm. 2 .

[0225] Example 2-3

[0226] The difference between Example 1 and Example 2 is that the mass content m1 of lithium transition metal phosphate is different.

[0227] Examples 4-5

[0228] Compared with Example 1, the difference lies in the coating thickness h1 and the separator thickness h.

[0229] Example 6

[0230] The difference from Example 1 is that a separator membrane with a coating on one side is used.

[0231] Examples 7-9

[0232] The difference between Example 1 and Example 2 is that the PVDF loading amount 'a' on one side of the separator is different.

[0233] Examples 10-11

[0234] Compared with Example 1, the difference lies in the average volume particle size Dv501 of the primary particles in the lithium transition metal oxide, which is different from that in Example 1.

[0235] Examples 12-13

[0236] The difference between Example 1 and Example 2 is that the coating weight CW1 on one side of the positive electrode sheet is different.

[0237] Comparative Example 1

[0238] The same housing with the same dimensions as in Example 1 was used. The difference between Example 1 and Example 2 is that a wound electrode assembly was used, and the thickness of the isolation film was 7 μm and the thickness of the coating on one side was 1 μm.

[0239] Comparative Example 2

[0240] The same housing with the same dimensions as in Example 1 was used. The difference between Example 3 and Example 1 is that a wound electrode assembly was used and the thickness of the isolation film was 22 μm.

[0241] Comparative Example 3

[0242] The stacked electrode assembly is used. The difference between Comparative Example 2 and Example 1 is that the thickness of the isolation membrane is 22 μm.

[0243] Product parameters and performance parameters of Examples 1-13 and Comparative Examples 1-3.

[0244] Table 1: Product parameters and performance parameters of Examples 1-13 and Comparative Examples 1-3

[0245] In Table 1, “m1” represents the mass content of lithium transition metal phosphate in the positive electrode active material; “h” represents the thickness of the separator 13, and “h1” represents the thickness of the coating on one side; “a” represents the one-side loading of binder particles on the separator; “D1” represents the average particle size of the lithium transition metal oxide particles; “CW1” represents the coating weight of the positive electrode film; “thermal runaway temperature” represents the temperature at which the secondary battery cell 20 experiences thermal runaway during the hot box test; and “VED” represents the volumetric energy density of the secondary battery cell 20.

[0246] Comparative analysis of the embodiments and comparative examples shows that, compared to comparative examples 1-3, the embodiments all exhibit superior thermal runaway temperatures, indicating that the safety performance of the embodiments is better than that of comparative examples 1-3. Furthermore, the embodiments also possess higher volumetric energy density than comparative example 1. This demonstrates that the material system and structural design of the counter electrode assembly 10 and the secondary battery cell 20 in the embodiments of this application can enable the secondary battery cell 20 to possess both high energy density and good safety performance.

[0247] Comparative analysis of Examples 1-3 shows that increasing the proportion of lithium-containing transition metal phosphate in the positive electrode active material increases the thermal runaway temperature of the secondary battery cell 20, improves safety performance, but decreases the volumetric energy density. Therefore, controlling the mass content of lithium-containing transition metal phosphate within a suitable range helps to obtain a secondary battery cell 20 that balances high energy density and high safety performance.

[0248] Comparative analysis of Examples 1 and 4-6 shows that a thicker coating and a thicker separator 13 result in a higher thermal runaway temperature for the secondary battery cell 20, which also affects the energy density of the secondary battery cell 20. Furthermore, a double-sided coating is more beneficial to the safety performance of the secondary battery cell 20. Therefore, by controlling the thickness of the separator 13 within a suitable range, a secondary battery cell 20 that balances high energy density and high safety performance can be obtained.

[0249] Comparative analysis of Examples 1 and 7-9 shows that at 0.5mg / 1540.25mm 2 -1.2mg / 1540.25mm 2 Within a certain range, the greater the loading of binder particles in the separator 13, the stronger the adhesion between the separator 13 and the electrode, resulting in better structural stability of the stacked electrode assembly composed of multiple positive and negative electrode sheets, and a higher thermal runaway temperature. However, in Example 9, the excessive loading of binder particles actually lowered the thermal runaway temperature. This may be because the binder blocks the ion channels in the separator 13, exacerbating the polarization of the secondary battery cells during cycling, thus reducing the thermal runaway temperature.

[0250] Comparative analysis of Examples 1 and 10-11 shows that a smaller average particle size of the lithium transition metal oxide particles is more conducive to improving the compaction density of the positive electrode sheet, resulting in a higher energy density of the secondary battery cell 20. Simultaneously, a smaller average particle size of the lithium transition metal oxide particles leads to a higher thermal runaway temperature and better safety performance in the secondary battery cell 20. This is likely because a smaller average particle size results in better structural stability of the lithium transition metal oxide, enabling more stable chemical reactions during the charge and discharge process of the secondary battery cell 20, thus reducing the probability of thermal runaway due to vigorous chemical reactions and excessive heat release. Therefore, controlling the average particle size of the lithium transition metal oxide particles helps to further improve the safety performance of the high-energy-density secondary battery cell 20.

[0251] Comparative analysis of Examples 1 and 12-13 shows that the greater the coating weight of the positive electrode 11, the higher the energy density of the secondary battery cell 20 and the lower the thermal runaway temperature. Therefore, adjusting the coating weight of the positive electrode can also help improve the safety performance of the high-energy-density secondary battery cell 20.

[0252] The following is a brief description of the testing methods for the physicochemical and performance parameters involved in the embodiments of this application. It should be understood that the following testing methods are only examples, and other testing methods known in the art can also be used for testing.

[0253] 1. Test methods for mass content

[0254] The specific types of lithium-containing transition metal oxides are determined by the mass ratio of Ni, Co, and Mn in CP-EDS, and the specific types of lithium-containing transition metal phosphates are determined by the mass ratio of Mn and Fe. Then, the mass content of lithium-containing transition metal oxides is calculated by the mass content of Ni in the ICP mixture, and the mass content of lithium-containing transition metal phosphates is calculated by the mass content of Fe.

[0255] 2. Test methods for element molar percentage

[0256] Test equipment: Inductively Coupled Plasma Emission Spectrometer (ICP).

[0257] Test method: Digestion: 1+1 aqua regia, digestion method: plate digestion / acid-removing digestion / microwave digestion (high temperature and high pressure ~200℃). The elemental mass fractions of nickel, cobalt, manganese, and doping elements were measured, and the molar amounts were calculated based on the molar mass of each element. Finally, the molar ratio of nickel, cobalt, and manganese was calculated by normalization.

[0258] 3. Test method for average particle size

[0259] The particle morphology and size of the sample were obtained using SEM. Elemental analysis was performed based on the SEM mapping results. Differences in element type and content (e.g., phosphorus) were used to distinguish between lithium transition metal phosphate particles and lithium transition metal oxide particles. The average particle size of the corresponding material was calculated based on the number of each type of particle in the SEM image and the major and minor axes of each particle.

[0260] 4. Dv50 Testing Method

[0261] Testing equipment: Particle size analyzer.

[0262] Pretreatment: Take a clean beaker, add an appropriate amount of the sample to be tested, add a surfactant and then add a dispersant, and sonicate at 120W / 5min to ensure that the sample is completely dispersed in the dispersant.

[0263] Test: After the sample is poured into the injection tower, it circulates with the solution to the test optical path system. Under the irradiation of the laser beam, the particle size distribution characteristics can be obtained by receiving and measuring the energy distribution of the scattered light (shading degree: 8-12%).

[0264] Calculation: Calculate the particle size at the 50% position of the volume distribution curve from smallest to largest, which is Dv50.

[0265] 5. Test method for electrode compaction density

[0266] Take a unit area of ​​the electrode to be tested, weigh the mass m1 of the material on the unit area electrode excluding the current collector, measure the electrode thickness T1 and the current collector thickness T0, and the compaction density = m1 / (T1-T0).

[0267] 6. Test method for film coating weight

[0268] Take a unit area of ​​the electrode to be tested and weigh the mass of the material on the unit area electrode, excluding the current collector, i.e., the coating weight.

[0269] 7. Test method for volumetric energy density of secondary battery cells

[0270] The secondary battery cell 20 is charged and discharged for 3 cycles at a current density of 0.33C within a voltage range of 2.5-4.25V on a charging and discharging device. The discharge energy Q of the third cycle is recorded. The volume V of the secondary battery cell 20 is measured by taking a CT scan image of the cell. Based on the CT scan image, the length T, height h, width L, diameter d of the electrode terminals, and height H of the secondary battery cell 20 can be measured. The volume of the secondary battery cell 20 can be calculated using the formula V = T × h × L + 2 × π × (d / 2). 2×H, the energy density of a single 20-cell secondary battery is Q / V (unit: Wh / L). If the electrode terminal is irregularly shaped, its volume can be calculated by fitting the irregular shape into a regular shape on a computer and then using the volume calculation formula for a regular shape.

[0271] 8. Safety performance testing methods

[0272] The safety performance of the secondary battery cell 20 was characterized by a hot box test. The specific test procedure was as follows: the fully charged secondary battery cell 20 was placed in an oven and heated from 30°C to 200°C at a temperature increase rate of 2°C / min, and held at 5°C for 30 minutes. The temperature at which the secondary battery cell 20 caught fire was observed, which is its failure temperature.

[0273] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A secondary battery cell, characterized by comprising: The secondary battery cell includes: A laminated electrode assembly including a positive electrode tab, a negative electrode tab, and a separator, the positive electrode tab including a positive electrode film layer including a positive electrode active material, the negative electrode tab including a negative electrode film layer including a negative electrode active material; The positive electrode active material includes a lithium-containing transition metal phosphate and a lithium-containing transition metal oxide, The thickness h of the separator satisfies 8 µm ≤ h ≤ 21 µm.

2. The secondary battery cell according to claim 1, characterized by The mass content m1 of the lithium-containing transition metal phosphate satisfies 40 wt% ≤ m1 ≤ 70 wt% based on the total mass of the positive electrode active material.

3. The secondary battery cell according to claim 1 or 2, characterized by The separator includes a base film and a coating layer provided on at least one side of the base film, and the thickness h1 of the coating layer on one side satisfies 3 µm ≤ h1 ≤ 6 µm.

4. The secondary battery cell according to claim 3, characterized by The coating layer includes heat-resistant particles including at least one of inorganic particles and organic particles.

5. The secondary battery cell according to claim 4, characterized by The inorganic particles include at least one of aluminum oxide, silicon oxide, titanium oxide, and barium titanate.

6. The secondary battery cell according to any one of claims 3 to 5, characterized by The coating layer includes binder particles including one or more of polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylonitrile, polyethylene oxide, a copolymer of different fluorine-containing alkenyl monomer units, a copolymer of fluorine-containing alkenyl monomer units and vinyl monomer units, a copolymer of fluorine-containing alkenyl monomer units and acrylic monomer units, a copolymer of fluorine-containing alkenyl monomer units and acrylate monomer units, and a modified compound of each of the above homopolymers or copolymers.

7. The secondary battery cell according to any one of claims 1 to 6, characterized by, The laminated electrode assembly includes a plurality of positive electrode tabs and a plurality of negative electrode tabs, and the plurality of positive electrode tabs and the plurality of negative electrode tabs are alternately stacked in a thickness direction.

8. The secondary battery cell according to claim 6 or 7, characterized by The single-side loading amount a of the binder particles on the separator film satisfies: 0.5 mg / 15 40.25 mm 2 ≤ a ≤ 1.2 mg / 15 40.25 mm 2 .

9. The secondary battery cell according to any one of claims 1 to 8, characterized by, The positive electrode tab includes a conductive agent including carbon nanotubes, and a diameter l of the carbon nanotubes satisfies 7 nm ≤ l ≤ 13 nm.

10. The secondary battery cell according to any one of claims 1 to 9, characterized by, The lithium-containing transition metal oxide has a particle with an average particle diameter D1 satisfying 2 µm ≤ D1 ≤ 5 µm.

11. The secondary battery cell according to any one of claims 1 to 10, characterized by, The lithium-containing transition metal oxide includes: Li 1+c [Ni x Co y Mn z M d ]O 2-e ; wherein M includes at least one of Zr, Al, Ti, Sb, Nb, Te, Mg, B, Ca, V, Ta, or Sr, 0.2 ≥ c ≥ -0.2, 0.95 ≥ x ≥ 0.5, 0.2 ≥ y ≥ 0.05, 0.3 > z > 0, 0.3 > d ≥ 0, and 0.5 ≥ e ≥ 0.

12. The secondary battery cell according to any one of claims 1 to 11, characterized by, The positive electrode tab satisfies at least one of the following (1) to (3): (1) the compacted density p1 of the positive electrode plate satisfies: 2.5 g / cm 3 ≤ p1 ≤ 2.9 g / cm 3 ; (2) the single-sided coating weight CW1 of the positive electrode film layer satisfies: 190 g / m 2 ≤ CW1≤ 230 g / m 2 ; (3) The thickness h1 of the positive electrode current collector satisfies 10 µm ≤ h1 ≤ 13 µm.

13. The secondary battery cell according to any one of claims 1 to 12, characterized by, The negative electrode tab satisfies at least one of the following (4) to (6): (4) the compacted density p2 of the negative electrode plate satisfies: 1.3 g / cm 3 ≤ p2 ≤ 1.55 g / cm 3 ; (5) the single-sided coating weight CW2 of the negative electrode film layer satisfies: 90 g / m 2 ≤ CW2≤ 110 g / m 2 ; (6) The thickness h2 of the negative electrode current collector satisfies 4 µm ≤ h2 ≤ 6 µm.

14. The secondary battery cell according to any one of claims 1 to 13, characterized by, The negative electrode active material includes graphite having an average volume particle diameter Dv502 satisfying 10 µm ≤ Dv502 ≤ 14 µm.

15. The secondary battery cell according to any one of claims 1 to 14, characterized by, The secondary battery includes an electrolyte including: a solvent including a linear carbonate; a mass content m2 of the linear carbonate satisfies 40 wt% ≤ m2 ≤ 70 wt% based on the total mass of the electrolyte.

16. The secondary battery cell according to claim 15, characterized by The electrolyte includes: a lithium salt including LiPF6 and LiFSI; The mass content m3 of the lithium salt satisfies 13wt%≤m3≤18wt% based on the total mass of the electrolyte.

17. The secondary battery cell according to claim 15 or 16, characterized by The ionic conductivity σ of the electrolyte at 25°C satisfies 7mS / cm≤σ≤10mS / cm.

18. The secondary battery cell according to any one of claims 1-17, characterized by, The secondary battery cell comprises a housing, a current collecting member; The housing is used to accommodate the jelly-roll electrode assembly, and the housing comprises a first wall provided with an electrode terminal; The jelly-roll electrode assembly comprises a main body and a tab connected to one end of the main body facing the first wall; The current collecting member is arranged between the first wall and the main body, and the current collecting member comprises a first connecting part and a second connecting part connected to each other, the first connecting part is connected to the electrode terminal, and the second connecting part is connected to the tab; In the thickness direction of the current collecting member, the thickness of the first connecting part is greater than the thickness of the second connecting part.

19. The secondary battery cell of claim 18, wherein, In the thickness direction of the current collecting member, the thickness D1 of the first connecting part satisfies 0.5mm≤D1≤1.2mm, and the thickness D2 of the second connecting part satisfies 0.3mm≤D2≤1mm.

20. The secondary battery cell of claim 19, wherein, 0.1mm≤D1-D2≤0.9mm.

21. The secondary battery cell according to any one of claims 18-20, characterized by The first wall comprises a first through hole; The electrode terminal comprises a main body part and a stepped part, at least part of the main body part is arranged in the first through hole, the stepped part protrudes from the outer peripheral surface of the main body part, and the stepped part is located on the side of the first wall facing the outside of the secondary battery cell; The secondary battery cell comprises a fixing member comprising a second through hole for the main body part to pass through; In the thickness direction of the first wall, at least part of the fixing member is located between the first wall and the stepped part and abuts against the stepped part, the main body part has a first end surface facing the outside of the secondary battery cell, the fixing member has a second end surface facing the outside of the secondary battery cell, and the first end surface exceeds the second end surface.

22. The secondary battery cell of claim 21, wherein, In the thickness direction of the first wall, the height difference H between the first end surface and the second end surface satisfies 0.5mm≤H≤1.5mm.

23. The secondary battery cell according to claim 21 or 22, characterized by In the radial direction of the main body part, the size W1 of the stepped part protruding from the outer peripheral surface of the main body part satisfies 0.1mm≤W1≤5mm.

24. A secondary battery characterized by comprising: The secondary battery comprises the secondary battery cell according to any one of claims 1-23.

25. An electrical device, comprising: The electric device comprises the secondary battery cell according to any one of claims 1-23 and / or the secondary battery according to claim 24.

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