Current collector, preparation method of current collector, battery monomer, battery device and power utilization device

Abstract

The invention belongs to the technical field of batteries, and particularly discloses a current collector, a preparation method of the current collector, a battery monomer, a battery device and a power utilization device. The battery cell provided by the invention comprises a current collector; the current collector comprises a metal layer; the metal layer comprises a metal substrate and a metal gate group positioned on at least one side surface of the metal substrate; the metal gate group comprises metal gate bars; the metal grid bars extend along a first direction and are arranged at intervals in a second direction; the first direction is different from the second direction; a groove is formed between every two adjacent metal grid bars, and a flame-retardant part is arranged in each groove. According to the battery monomer provided by the invention, the probability of further thermal runaway is reduced when the battery is short-circuited.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to a current collector, a method for preparing the current collector, a battery cell, a battery device, and an electrical device. Background Art

[0002] With the development of new energy technology, batteries are used more and more widely, such as in mobile phones, laptops, battery cars, electric cars, energy storage devices, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools, etc. This places higher and higher requirements on battery performance. Summary of the invention

[0003] In view of the above problems, the present application provides a current collector, a method for preparing the current collector, a battery cell, a battery device and an electric device. The battery cell reduces the probability of thermal runaway when a short circuit occurs in the battery.

[0004] In a first aspect, the present application provides a battery cell, the battery cell comprising a current collector and an active material layer located on at least one side surface of the current collector;

[0005] The current collector includes a metal layer;

[0006] The metal layer comprises a metal substrate and a metal grid group located on at least one side of the metal substrate;

[0007] The metal grid group includes metal bars;

[0008] The metal bars extend along a first direction and are arranged at intervals in a second direction; the first direction is different from the second direction;

[0009] A groove is formed between adjacent metal bars, and a flame retardant is arranged in the groove;

[0010] The orthographic projections of the flame retardant and the metal grid group on the metal base overlap with the metal base.

[0011] When a short circuit occurs in the battery cell of the present application, the flame retardant located between the metal bars can absorb part of the heat generated by the short circuit to cool the battery cell, and when the short circuit current is large enough, the instantaneous overload of electrons will cause the connected metal bars to melt, thereby preventing the short circuit from continuing to occur and disconnecting the circuit, reducing the probability of thermal runaway of the battery.

[0012] In some embodiments, the first direction and the second direction form an angle α, 0°<α≤90°.

[0013] The first direction of the present application refers to the extension direction of the metal grid, and the second direction refers to the spacing arrangement direction of the metal grids. The angle formed between the two satisfies the above range, which facilitates the arrangement of the metal grids.

[0014] In some embodiments, along the third direction, the metal layer includes a first surface and a second surface that are oppositely disposed, and a distance between the first surface and the second surface is H;

[0015] Along the third direction, the metal grid includes an A surface and a B surface that are arranged opposite to each other, and the distance between the A surface and the B surface is h;

[0016] Satisfy: 0.1≤h / H≤0.9;

[0017] The third direction is different from both the first direction and the second direction.

[0018] In the present application, in order to enable the metal layer to play the role of collecting current when the battery is operating normally, and to facilitate the metal grid to fuse when the electrons are instantly overloaded when the battery is short-circuited, the thickness h of the metal grid and the thickness H of the metal layer need to meet certain conditions. Within the numerical range of the present application, the functions of the above-mentioned different stages can be well exerted.

[0019] In some embodiments, an angle formed by the third direction and the first direction is 90°, and an angle formed by the third direction and the second direction is 90°.

[0020] In some embodiments, the metal grid group includes a first metal grid bar and a second metal grid bar that are adjacently arranged;

[0021] Along the second direction, the first metal grid includes a C surface and a D surface that are arranged opposite to each other;

[0022] The second metal grid comprises a C' surface and a D' surface which are arranged opposite to each other, wherein the C' surface is arranged close to the D surface, and the D' surface is arranged far away from the D surface;

[0023] The distance between the above-mentioned surface C and surface D is y;

[0024] The distance between the C surface and the C' surface is x;

[0025] Satisfies: 0.1≤y / x≤0.9.

[0026] As mentioned above, the present application needs to ensure that when a short circuit occurs in the battery, the metal grid is melted when the electrons are overloaded instantly, and the flame retardant is required to separate the adjacent metal grids and also achieve good heat absorption and heat insulation. Therefore, the present application needs to limit the width of the metal grid and the flame retardant in the second direction. The present application chooses to meet the above range value, which is conducive to the above function being well exerted.

[0027] In some embodiments, the thermal conductivity of the current collector is 0.01 W / (K·m) to 500 W / (K·m).

[0028] In some embodiments, the active material layer comprises a positive electrode active material layer;

[0029] The positive electrode active material layer includes a positive electrode active material;

[0030] The positive electrode active material includes a nickel cobalt manganese oxide lithium layered oxide;

[0031] The chemical formula of the lithium nickel cobalt manganese oxide layered oxide is Li t (Ni a Co b Mn c ) 1-d M d O 2-v A v ;

[0032] M includes any one or more of Zr, Sr, B, Ti, Mg, Sn and Al;

[0033] A represents an oxygen doping element, and the oxygen doping element includes any one or more of S, N, F, Cl, Br and I;

[0034] t is 0.2 to 1.2;

[0035] a≥0.5; 0<b<0.2; a+b+c=1,

[0036] 0≤d≤0.1;

[0037] 0≤v<0.2.

[0038] The present application does not make any special limitation on the positive electrode active material of the battery cell. Among them, lithium nickel cobalt manganese oxide layered oxide has a high capacity, but it is prone to release a large amount of heat in a short period of time when the battery is short-circuited or overcharged. This active material is combined with the current collector of the present application to help reduce the probability of the above-mentioned thermal runaway of the battery.

[0039] In some embodiments, the battery cell includes a separator;

[0040] The isolation element comprises a substrate and a coating located on at least one surface of the substrate, wherein the coating comprises any one or more of an organic coating or an inorganic coating.

[0041] The organic coating or inorganic coating of the present application plays an insulating role, reducing the probability of short circuit caused by piercing the separator. That is, the present application adopts a separator including a coating, which first reduces the probability of short circuit. Even if a short circuit occurs, the current collector designed by the present application can improve safety by cutting off the short circuit in a short time.

[0042] In some embodiments, the battery cell comprises an electrolyte;

[0043] The electrolyte comprises an ionic liquid additive, wherein the cation of the ionic liquid additive comprises any one or more of nitrogen-containing onium ions and phosphorus-containing onium ions, and the anion of the ionic liquid additive comprises any one or more of halogen ions, phosphate ions, borate ions, and sulfonimide anions.

[0044] The ionic liquid additives in the electrolyte of the present application have high thermal stability and low volatility. At the same time, the ionic liquid additives can also improve the stability of the negative electrode active material by forming a solid electrolyte interface film (SEI) and improving the stability of the film, thereby improving the safety of the battery.

[0045] In some embodiments, the metal substrate and the metal grid group include any one or more of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, iron, iron alloy, titanium, titanium alloy, silver and silver alloy;

[0046] In some embodiments, the flame retardant comprises any one or more of an organic flame retardant and an inorganic flame retardant.

[0047] In some embodiments, the organic flame retardant includes any one or more of phosphonates, dicyclopentadiene, aliphatic halogenated hydrocarbons, aromatic halogenated compounds, and nitrogen series;

[0048] The inorganic flame retardant includes any one or more of expanded graphite, metal hydroxide, boron salt, and phosphate.

[0049] In some embodiments, the current collector includes an organic support layer and a metal layer located on at least one surface of the organic support layer.

[0050] In some embodiments, the current collector includes an organic support layer, and a first metal layer and a second metal layer respectively located on both side surfaces of the organic support layer;

[0051] A negative electrode active material layer is provided on a surface of the first metal layer away from the organic support layer;

[0052] A positive electrode active material layer is provided on a surface of the second metal layer away from the organic support layer.

[0053] A second aspect of the present application is to provide a current collector, comprising a metal layer;

[0054] The metal layer comprises a metal substrate and a metal grid group located on at least one side of the metal substrate;

[0055] The metal grid group includes metal bars;

[0056] The metal bars extend along a first direction and are arranged at intervals in a second direction; the first direction is different from the second direction;

[0057] A groove is formed between adjacent metal bars, and a flame retardant is arranged in the groove;

[0058] The orthographic projections of the flame retardant and the metal grid group on the metal base overlap with the metal base.

[0059] The third aspect of the present application is to provide a method for preparing the current collector according to the second aspect, comprising the following process:

[0060] providing a metal layer;

[0061] Masking and etching are performed on the surface of either side of the metal layer to form a metal substrate and a metal gate group;

[0062] preparing a flame retardant slurry;

[0063] Applying the flame retardant slurry into the grooves formed between adjacent metal bars;

[0064] The current collector is obtained by drying.

[0065] In some embodiments, preparing a flame retardant slurry includes:

[0066] The flame retardant and the binder are mixed in a mass ratio of 9:1, added into deionized water, and stirred to form a slurry with a solid content of 45% to 55%.

[0067] A fourth aspect of the present application is to provide a battery device, comprising the battery cell described in the first aspect.

[0068] The fifth aspect of the present application is to provide an electrical device, comprising the battery device described in the fourth aspect.

[0069] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0071] Figure 1 A schematic diagram of the battery structure of some embodiments of the present application;

[0072] Figure 2 This is a schematic diagram of the exploded structure of batteries in some embodiments of the present application;

[0073] Figure 3 A schematic diagram of a vehicle structure of some embodiments of the present application;

[0074] Figure 4 A schematic diagram of the structure of a battery pack according to some embodiments of the present application;

[0075] Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 This is a schematic diagram of the structure of the current collector in some embodiments of the present application;

[0076] Fig.10 A schematic structural diagram of the positional relationship between the positive electrode sheet, the separator and the negative electrode sheet in some embodiments of the present application;

[0077] Fig.11 This is a schematic diagram of the structure of the positive electrode sheet of some embodiments of the present application;

[0078] Fig.12 A schematic diagram of the structure of another current collector in some embodiments of the present application;

[0079] Fig.13 This is a schematic diagram of the structure of the electrode plates of some embodiments of the present application.

[0080] The reference numerals in the specific implementation manner are as follows:

[0081] 10000, vehicles;

[0082] 1000, battery; 2000, controller; 3000, motor;

[0083] 100. Battery cell;

[0084] 200, box body; 210, first part; 220, second part;

[0085] 10. Secondary battery;

[0086] 101, housing; 102, electrode assembly; 103, cover plate;

[0087] 1. Negative electrode sheet; 11. Negative electrode active material layer;

[0088] 2. positive electrode plate; 21. positive electrode active material layer;

[0089] 3. Isolation parts;

[0090] 4, current collector; 41, metal layer; 41', first metal layer; 41", second metal layer;

[0091] 41a, metal substrate; 41b, metal grid group; 41b1, metal grid bar; 41b1-1, first metal grid bar;

[0092] 41b1-2, second metal grid;

[0093] 411, first page;

[0094] 412, second side;

[0095] 41c, groove; 41d, flame retardant;

[0096] 42. Organic support layer;

[0097] Side A and Side B: surfaces on which metal bars are arranged opposite to each other along the third direction;

[0098] Surface C and Surface D: surfaces on which the first metal grid is arranged opposite to each other along the second direction;

[0099] C' surface, D' surface: surfaces on which the second metal grids are arranged opposite to each other along the second direction;

[0100] First direction: the extension direction of the metal grid;

[0101] The second direction: the direction of the metal grid arrangement, or the coordinate axis y direction;

[0102] The third direction: the coordinate axis z direction, which can also be the thickness direction or stacking direction of the current collector. DETAILED DESCRIPTION

[0103] Below, the current collector, the method for preparing the current collector, the battery cell, the battery device and the implementation method of the power device of the present application are specifically disclosed with appropriate reference to the drawings. However, there are cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0104] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that a range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0105] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0106] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0107] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0108] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0109] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": 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).

[0110] If not otherwise specified, in this application, the terms "first", "second", etc. are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary and secondary relationship of the indicated technical features.

[0111] Unless otherwise specified, in this application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple sheets" refers to more than two sheets (including two sheets).

[0112] Unless otherwise specified, the orientations or positional relationships indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present application.

[0113] Batteries have been widely used in various products due to their high energy density, long cycle life, safety and reliability. In recent years, as the demand for batteries as energy has increased significantly, higher requirements have been placed on battery performance, such as safety.

[0114] Based on the above considerations, in order to improve the safety of the battery, the present application conducted relevant experimental research and obtained a current collector, a method for preparing the current collector, a battery cell, a battery device and an electrical device.

[0115] First, the application discloses a battery cell, which includes a current collector and an active material layer located on at least one side of the current collector; the current collector includes a metal layer; the metal layer includes a metal substrate and a metal grid group located on at least one side of the metal substrate; the metal grid group includes metal bars; the metal bars extend along a first direction and are arranged at intervals in a second direction; the first direction is different from the second direction; a groove is formed between adjacent metal bars, a flame retardant is provided in the groove, and the orthographic projection of the flame retardant and the metal grid group on the metal substrate overlaps with the metal substrate.

[0116] When a short circuit occurs in the battery cell provided by the present application, the flame retardant located between the metal bars can absorb part of the heat generated by the short circuit to cool the battery cell, and when the short circuit current is large enough, the instantaneous overload of electrons will cause the connected metal bars to melt, thereby preventing the short circuit from continuing to occur and disconnecting the circuit, reducing the probability of thermal runaway when a short circuit occurs in the battery.

[0117] Therefore, the battery cell provided in this application is helpful to improve user experience.

[0118] Electrode assembly

[0119] A battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator, which is arranged between the negative electrode sheet and the positive electrode sheet. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, which can prevent the positive and negative electrodes from short-circuiting, and at the same time allow active ions to pass through.

[0120] Battery device

[0121] The battery apparatus mentioned in the embodiments of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include multiple battery cells, which are connected in series, in parallel or in mixed connection through a busbar component.

[0122] In some embodiments, a battery cell assembly is generally formed by arranging a plurality of battery cells.

[0123] As an example, the battery cell assembly may be a battery module, which is formed by arranging and fixing a plurality of battery cells to form an independent module. As an example, the battery module may be formed by bundling a plurality of battery cells by a cable tie.

[0124] In some embodiments, the battery device may be a battery pack, which includes a case and one or more battery cell assemblies, wherein the battery cell assemblies are accommodated in the case.

[0125] As an example, the battery cell assembly may be a battery module, and the battery cell assembly may be accommodated in the box by fixing the battery module in the box.

[0126] As an example, the battery cell assembly may also be housed in the case by directly fixing a plurality of battery cells to the case.

[0127] As an example, the box may include a first box and a second box. The first box and the second box are buckled together to form a closed space inside the box to accommodate the battery cell assembly. The closed here means covered or closed, which can be sealed or unsealed. The first box can be a top cover or a bottom plate.

[0128] As an example, the box body may include a top cover, a frame and a bottom plate. The top cover and the bottom plate are respectively connected to the frame, so that a closed space is formed inside the box body to accommodate the battery cell assembly.

[0129] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0130] The battery cell of the present application may include an outer packaging. The outer packaging may be used to encapsulate the electrode assembly and electrolyte composed of the above-mentioned battery cell. The outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery cell may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and the plastic includes but is not limited to polypropylene, polybutylene terephthalate, and polybutylene succinate, etc.

[0131] The present application has no particular limitation on the shape of the battery, which may be cylindrical, square or any other shape. For example, Figure 1 The secondary battery 10 is a square structure as an example.

[0132] According to some embodiments of the present application, Figure 2 , the outer packaging may include a shell 101 and a cover plate 103. Among them, the shell 101 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 101 has an opening connected to the receiving cavity, and the cover plate 103 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation film can form an electrode assembly 102 through a winding process or a lamination process. The electrode assembly 102 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 102. The number of electrode assemblies 102 contained in the secondary battery 10 can be one or more, and those skilled in the art can select according to specific actual needs.

[0133] The electrode assembly 102 provided in the present application is applied to a battery cell, which is beneficial to improving the performance of the battery cell. The battery cell can be used as a power source for an electrical device or as an energy storage unit for an electrical device. The electrical device is applied to the power field, such as mobile devices (such as mobile phones, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but not limited to the above-mentioned fields.

[0134] For the convenience of explanation, some embodiments of the present application are described by taking a vehicle as an example of an electrical device.

[0135] Please refer to Figure 3 , Figure 3 A schematic diagram of the structure of a vehicle 10000 provided for some embodiments of the present application. The vehicle 10000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 1000 is provided inside the vehicle 10000, and the battery 1000 may be provided at the bottom, head or tail of the vehicle 10000. The battery 1000 may be used to power the vehicle 10000, for example, the battery 1000 may be used as an operating power source for the vehicle 10000. The vehicle 10000 may also include a controller 2000 and a motor 3000, and the controller 2000 is used to control the battery 1000 to power the motor 3000, for example, for the starting, navigation and working power requirements of the vehicle 10000 during driving.

[0136] In some embodiments of the present application, the battery 1000 can not only serve as the operating power source of the vehicle 10000, but also serve as the driving power source of the vehicle 10000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 10000.

[0137] Please refer to Figure 4 , Figure 4 An exploded view of a battery 1000 provided in some embodiments of the present application. The battery 1000 includes a housing 200 and a battery cell 100. Conventional battery cells include primary batteries or secondary batteries. The present application specifically protects secondary batteries 10. The battery cell 100 is accommodated in the housing 200. The housing 200 is used to provide a storage space for the battery cell 100. The housing 200 can adopt a variety of structures.

[0138] In some embodiments, the box 200 may include a first portion 210 and a second portion 220, the first portion 210 and the second portion 220 cover each other, and the first portion 210 and the second portion 220 jointly define a storage space for accommodating the battery cell 100. The second portion 220 may be a hollow structure with one end open, and the first portion 210 may be a plate-like structure, and the first portion 210 covers the open side of the second portion 220, so that the first portion 210 and the second portion 220 jointly define a storage space; the first portion 210 and the second portion 220 may also be hollow structures with one side open, and the open side of the first portion 210 covers the open side of the second portion 220. Of course, the box 200 formed by the first portion 210 and the second portion 220 may be in various shapes, such as a cylinder, a cuboid, etc.

[0139] In the battery 1000, there may be multiple battery cells 100, and the multiple battery cells 100 may be connected in series, in parallel, or in a mixed connection. A mixed connection means that the multiple battery cells 100 are both connected in series and in parallel. The multiple battery cells 100 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 100 is accommodated in the box 200; of course, the battery 1000 may also be a battery 1000 module formed by connecting multiple battery cells 100 in series, in parallel, or in a mixed connection, and then the multiple battery 1000 modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 200. The battery 1000 may also include other structures, for example, the battery 1000 may also include a busbar component for realizing electrical connection between the multiple battery cells 100.

[0140] Battery Cell

[0141] In some embodiments, the present application discloses a battery cell, which includes a current collector and an active material layer located on at least one side of the current collector; the current collector includes a metal layer; the metal layer includes a metal substrate and a metal grid group located on at least one side of the metal substrate; the metal grid group includes metal bars; the metal bars extend along a first direction and are arranged at intervals in a second direction; the first direction is different from the second direction; a groove is formed between adjacent metal bars, and a flame retardant is provided in the groove; the flame retardant and the metal grid group have their orthographic projections on the metal substrate overlapping with the metal substrate.

[0142] The battery cell of the present application may be a secondary battery, which refers to a battery cell that can be used continuously by activating the active material by charging after the battery cell is discharged. The battery cell may be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead storage battery, etc., and the embodiments of the present application are not limited thereto.

[0143] The current collector of the present application refers to a structure or component for collecting current, which can collect the current generated by the active material of the battery to form a larger current for external output, and at the same time, its own internal resistance is small enough.

[0144] like Figure 5 As shown, the current collector 4 of the present application includes a metal layer 41, and the metal layer 41 includes a metal substrate 41a and a metal grid group 41b, wherein the metal grid group 41b is located on at least one side surface of the metal substrate 41a. Figure 5 FIG. 4 shows only a metal grid group 41b disposed on one side of the metal substrate 41a. The metal grid group 41b includes metal grid bars 41b1, such as Figure 6 As shown in FIG. 1 , each metal grid 41b1 extends along the first direction and is arranged at intervals in the second direction; Figure 5 As shown in FIG. 4 , a groove 41c is formed between adjacent metal bars 41b1; Figure 6 As shown, a flame retardant 41d is disposed in the groove 41c.

[0145] The flame retardant of the present application refers to a flame retardant component that absorbs heat to reduce the ambient temperature to reduce combustion. The present application sets a flame retardant 41d between each metal grid 41b1 to separate each adjacent metal grid 41b1, which is conducive to the metal grid fusing when the electron is overloaded instantly.

[0146] The orthographic projections of the flame retardant 41d and the metal grid group 41b of the present application on the metal base 41a overlap with the metal base 41a, so that the flame retardant 41d can fully and effectively block the adjacent metal grid 41b1, thereby facilitating the melting of the metal grid when the electrons are instantly overloaded.

[0147] Combination Figure 6 It can be seen that the metal bars 41b1 of the present application are arranged flush with the flame retardant parts 41d, which not only plays the role of isolating the conduction of adjacent metal bars 41b1, but also reduces the impact on conductivity. On the other hand, it also facilitates the subsequent formation of an active material layer on the surface of the current collector.

[0148] As shown in the above-mentioned figures, the metal bars and flame retardants of the present application each include a plurality of them. In these embodiments, the present application further selects that the sizes of the metal bars and the flame retardants are consistent, which is beneficial to the uniformity of the current when the internal circuit of the battery is turned on and increases the probability of a circuit break after a short circuit.

[0149] Therefore, when a short circuit occurs in the battery cell of the present application, the flame retardant located between the metal bars can absorb part of the heat generated by the short circuit to cool the battery cell, and when the short circuit current is large enough, the instantaneous overload of electrons will cause the connected metal bars to melt, thereby preventing the short circuit from continuing to occur and disconnecting the circuit, reducing the probability of thermal runaway of the battery.

[0150] The battery short circuit of the present application includes external wire short circuit and internal short circuit. External wire short circuit means that when the positive and negative electrodes of the external wire are in contact, the current will flow directly from the positive electrode to the negative electrode without passing through the electrolyte and diaphragm inside the battery, resulting in a runaway electrochemical reaction. Internal short circuit means that there is a conductive material (such as a metal sheet) or electrolyte leakage between the positive and negative electrodes of the battery, which will form an internal short circuit of the battery. In addition, it also includes a short circuit caused by over-discharge of the battery, or a battery short circuit caused by mechanical damage to the battery shell. Battery short circuit can easily cause the battery to release a large amount of current or cause thermal runaway such as fire and explosion.

[0151] In some embodiments, the first direction and the second direction form an angle α, 0°<α≤90°.

[0152] The first direction of the present application refers to the extension direction of the metal bars, and the second direction refers to the spacing arrangement direction of the metal bars. The present application discloses in these embodiments that the angle α formed by the first direction and the second direction is any one of 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90° or any one of the ranges of any two of the above.

[0153] like Figure 7 As shown in Figure A, the angle formed by the first direction and the second direction is 90°, the first direction refers to the x direction of the coordinate axis, and the second direction refers to the y direction of the coordinate axis.

[0154] like Figure 7 As shown in Figure B, the angle formed by the first direction and the second direction is less than 90°, the first direction does not refer to the x direction of the coordinate axis, and the second direction refers to the y direction of the coordinate axis.

[0155] This application is Figure 7 Only a portion of the metal grid arrangement structure diagram is shown in FIG. No matter which arrangement is used, the metal grid can be melted when the electrons are overloaded instantly.

[0156] In some embodiments, along the third direction, the metal layer includes a first surface and a second surface arranged opposite to each other, and the distance between the first surface and the second surface is H; along the third direction, the metal grid includes an A surface and a B surface arranged opposite to each other, and the distance between the A surface and the B surface is h; it satisfies: 0.1≤h / H≤0.9; the third direction is different from the first direction and the second direction.

[0157] The third direction in this application refers to the thickness direction of the current collector, which is also the stacking direction of the film layers on the current collector. Figure 8 Schematically, the metal layer 41 includes a first surface 411 and a second surface 412, the distance between the first surface 411 and the second surface 412 is H, and the metal grid 41b1 includes an A surface and a B surface, wherein the A surface and the first surface 411 can refer to surfaces located in the same plane, and the distance between the A surface and the B surface is h.

[0158] like Figure 8 As shown in the figure, the thickness H of the metal layer 41 is greater than the thickness h of the metal grid 41b1, and the two satisfy: 0.1≤h / H≤0.9. This is because, in order for the metal layer to play the role of collecting current when the battery is working normally, and to facilitate the metal grid to fuse when the electrons are instantly overloaded when the battery is short-circuited, the thickness h of the metal grid 41b1 needs to meet certain conditions, and within the numerical range of the present application, it can well play the functions of the above-mentioned different stages.

[0159] In these embodiments, the present application discloses that the value of h / H is any one of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or any one of the values ​​within the range of any two of the above values.

[0160] In some embodiments, an angle formed by the third direction and the first direction is 90°, and an angle formed by the third direction and the second direction is 90°.

[0161] As mentioned above, the third direction refers to the thickness direction of the current collector, which is perpendicular to both the first direction and the second direction.

[0162] In some embodiments, the above-mentioned metal grid group includes a first metal grid and a second metal grid arranged adjacent to each other; along the second direction, the first metal grid includes a C surface and a D surface arranged opposite to each other; the second metal grid includes a C' surface and a D' surface arranged opposite to each other, the C' surface is arranged close to the D surface, and the D' surface is arranged away from the D surface; the distance between the C surface and the D surface is y; the distance between the C surface and the C' surface is x; satisfying: 0.1≤y / x≤0.9.

[0163] like Fig. 9 Schematically, the metal grid group 41b includes a first metal grid 41b1-1 and a second metal grid 41b1-2 that are adjacent to each other, the first metal grid 41b1-1 includes a C surface and a D surface that are relatively arranged, and the second metal grid 41b1-2 includes a C' surface and a D' surface that are relatively arranged, the C' surface is arranged close to the above-mentioned D surface, and the D' surface is arranged away from the above-mentioned D surface; the distance between the C surface and the D surface is y, and the distance between the C surface and the C' surface is x.

[0164] As mentioned above, in order to enable the metal layer to play the role of collecting current when the battery is working normally, and to facilitate the metal grid to fuse when the electrons are instantly overloaded when the battery is short-circuited, in addition to further limiting the thickness h of the metal grid, the present application also needs to limit the size of the metal grid in the second direction. When the above-mentioned numerical range is met, the metal grid can further perform better.

[0165] In these embodiments, the present application discloses that the value of y / x is any one of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9, or any one of the values ​​within the range of any two of the above values.

[0166] The battery cell of the present application includes an electrode plate, the electrode plate includes a current collector and an active material layer located on at least one side of the current collector, the active material layer includes a positive electrode active material layer, the positive electrode active material layer includes a positive electrode active material, and the present application does not specifically limit the type of the positive electrode active material.

[0167] In some embodiments, the thermal conductivity of the current collector is 0.01 W / (K·m) to 500 W / (K·m).

[0168] The thermal conductivity of the current collector of the present application can be measured using instruments and methods known in the art, such as using a thermal conductivity meter, including: cutting the current collector into a 5 cm×5 cm sample, and measuring the thermal conductivity of the sample using a TC3000 thermal conductivity meter. The specific test method can refer to the national standard GBT 10294-2008.

[0169] The thermal conductivity of the current collector of the present application is affected by the structural composition of the current collector. If the current collector includes a metal layer and a flame retardant, the flame retardant has little effect on the thermal conductivity of the metal layer, so the thermal conductivity of the current collector will still be large. If the current collector includes an organic support layer in addition to the above-mentioned metal layer and flame retardant, since the thermal conductivity of the organic support layer is small, it also has a relatively large impact on the thermal conductivity of the entire current collector, so the thermal conductivity of the current collector becomes smaller. The present application gives specific values ​​of the current collector in subsequent specific embodiments.

[0170] In some embodiments, the positive electrode active material includes a nickel cobalt manganese oxide lithium layered oxide; the chemical formula of the nickel cobalt manganese oxide lithium layered oxide is Li t (Ni a Co b Mn c ) 1-d M d O 2-v A v; M includes any one or more of Zr, Sr, B, Ti, Mg, Sn and Al; A represents an oxygen doping element, and the oxygen doping element includes any one or more of S, N, F, Cl, Br and I; t is 0.2 to 1.2; a≥0.5; 0<b<0.2; a+b+c=1, 0≤d≤0.1;

[0171] 0≤v<0.2.

[0172] The nickel cobalt manganese oxide lithium layered oxide of the present application has a high capacity, but is prone to releasing a large amount of heat in a short period of time when the battery is short-circuited or overcharged. The active material combined with the current collector of the present application is beneficial to reducing the probability of the above-mentioned thermal runaway of the battery.

[0173] The present application discloses in these embodiments that t is any one of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, and 1.2, or any one of the values ​​satisfying any two ranges thereof.

[0174] The present application discloses in these embodiments that a is any one of 0.5, 0.6, 0.7, 0.8, 0.9 or any one of the values ​​satisfying any two of the above ranges.

[0175] The present application discloses in these embodiments that b is any one of 0.05, 0.1, 0.15 or any one of the values ​​satisfying any two of the above ranges.

[0176] The present application discloses in these embodiments that d is any one of 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, or any one of the values ​​satisfying any two of the above ranges.

[0177] The present application discloses in these embodiments that v is any one of 0, 0.05, 0.1, 0.15, 0.16 or any one of the values ​​satisfying any two of the above ranges.

[0178] In some embodiments, the battery cell comprises an isolator; the isolator comprises a substrate, and a coating located on at least one surface of the substrate; the coating comprises any one or more of an organic coating or an inorganic coating.

[0179] The organic coating of the present application includes a polymer coating, and the polymer material of the polymer coating includes one or more of polyethylene (PE), polypropylene (PP), poly(p-phenylene terephthalamide) (PPTA), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyacrylonitrile (PAN), polyimide (PI) and polyamide (PA).

[0180] The inorganic coating of the present application includes a ceramic coating, and the ceramic particles in the ceramic coating include SiO 2 、Al 2 O 3 、AlOOH、CaO、TiO 2 ,MgO,ZnO,ZrO 2 Mg(OH) 2 and BaSO 4 One or more of .

[0181] The organic coating or inorganic coating of the present application plays an insulating role, reducing the probability of short circuit caused by piercing the separator. That is, the present application adopts a separator including a coating, which first reduces the probability of short circuit. Even if a short circuit occurs, the current collector designed by the present application can improve safety by cutting off the short circuit in a short time.

[0182] In some embodiments, the battery cell includes an electrolyte; the electrolyte includes an ionic liquid additive, the cation of the ionic liquid additive includes any one or more of nitrogen-containing onium ions and phosphonium ions, and the anion of the ionic liquid additive includes any one or more of halogen ions, phosphate ions, borate ions, and sulfonyl imide anions.

[0183] In this application, the electrolyte is the carrier of ion transmission in the battery, and plays the role of conducting ions between the positive and negative electrodes of the battery. The type of electrolyte affects the safety of the battery. Ionic liquid additives refer to salts that are added to the electrolyte in a relatively small amount, are completely composed of cations and anions, and are liquid at room temperature or near room temperature, where room temperature refers to 25°C ± 5°C. Ionic liquid additives themselves have high thermal stability and low volatility. At the same time, the ionic liquid additives can also improve the stability of the negative electrode active material by forming a solid electrolyte interface film (SEI) and improving the stability of the film, thereby improving the safety of the battery.

[0184] In some embodiments, the cation of the ionic liquid additive comprises 1-butyl-3-methylimidazolium ([Bmin] + )、1-benzyl-3-methylimidazolium ([Bzmin] + ), 3-methyl-1-ethoxycarbonylmethylimidazolium ([Etmim] + )、1-alkyl-3-methylimidazolium ([Cnmim] + ), 1-[(trimethylsilyl)methyl]benzotriazolium ([SiMBIM] + )、N-alkyl-N-methylpiperidinium ([CnC1pip] + ), 5-azoniaspiro[4.4]nonane ([AS[mn]] +), trihexyl(tetradecyl)phosphine ion ([Tf2N] + ), tetrabutylphosphine ion ([Pnnnn] + ), n-butyl-N-methylpyrrolidinium ([Pyr 14 ] + ) can be one or more of tetrabutylphosphine ion or n-butyl-N-methylpyrrolidinium.

[0185] In some embodiments, the anion of the ionic liquid additive comprises a chloride ion ([Cl] - ), bromide ion ([Br] - ), iodide ion ([I] - ), hexafluorophosphate ([PF 6 ] - ), tetrafluoroborate ([BF 4 ] - ), dicyandiamide anion ([N(CN) 2 ] - ), bis(fluorosulfonyl)imide anion ([FSI] - ), bis(trifluoromethylsulfonyl)imide ([TFSI] - ) can be one or more of hexafluorophosphate or bis(fluorosulfonyl)imide anions.

[0186] In some embodiments, the ionic liquid additive includes one or more of tetrabutylphosphine hexafluorophosphate, tetrabutylphosphine bis(fluorosulfonyl)imide, n-butyl-N-methylpyrrolidine hexafluorophosphate, n-butyl-N-methylpyrrolidine bis(fluorosulfonyl)imide, 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-benzyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-benzyl-3-methylimidazolium bis(fluorosulfonyl)imide, and further includes tetrabutylphosphine hexafluorophosphate, tetrabutylphosphine bis(fluorosulfonyl)imide, n-butyl-N-methylpyrrolidine hexafluorophosphate, and n-butyl-N-methylpyrrolidine bis(fluorosulfonyl)imide.

[0187] In some embodiments, the metal substrate and the metal gate group include any one or more of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, iron, iron alloy, titanium, titanium alloy, silver and silver alloy.

[0188] In some embodiments, the flame retardant comprises any one or more of an organic flame retardant and an inorganic flame retardant.

[0189] In some embodiments, the organic flame retardant includes any one or more of phosphonates, dicyclopentadiene, aliphatic halogenated hydrocarbons, aromatic halogenated compounds, and nitrogen series;

[0190] The inorganic flame retardant includes any one or more of expanded graphite, metal hydroxide, boron salt, and phosphate.

[0191] The phosphonates of the present application include any one or more of bisphenol A bis(diphenyl phosphate), bisphenol A bis(triphenyl phosphate), tetrakis(2,4-di-tert-butylphenyl)[1,1-biphenyl]-4,4-diyl diphosphite, resorcinol bis(diphenyl phosphate) and phosphazene.

[0192] The aliphatic halogenated hydrocarbons of the present application include decabromodiphenylethane.

[0193] The aromatic halogenated compound of the present application includes tetrabromobisphenol A.

[0194] The nitrogen system of the present application includes dicyandiamide.

[0195] The metal hydroxide of the present application includes any one or more of aluminum hydroxide and magnesium hydroxide.

[0196] The boron salt of the present application includes at least one of metaborate, orthoborate and polyborate: metaborate includes at least one of calcium metaborate, barium metaborate, sodium metaborate and ammonium metaborate; orthoborate includes zinc borate; polyborate includes at least one of ammonium pentaborate and sodium tetraborate.

[0197] The phosphate of the present application includes any one or more of diammonium hydrogen phosphate, ammonium dihydrogen phosphate, and ammonium phosphate.

[0198] The flame retardant component of the present application is formed by coating or deposition.

[0199] The flame retardant component of the present application includes not only the flame retardant mentioned above, but also a binder. The binder of the present application includes any conventional type in the art, such as polyvinylidene fluoride and polyacrylate.

[0200] The flame retardant component of the present application contains a flame retardant and a binder, and the mass ratio of the flame retardant and the binder is 9:1.

[0201] In some embodiments, the present application discloses an electrode sheet formed by the above-mentioned current collector and active material layer.

[0202] In some embodiments, the electrode plate includes a positive electrode plate or a negative electrode plate, and the electrode plate includes a current collector and an active material layer located on at least one side of the current collector.

[0203] The positive electrode sheet 2, the separator 3 and the negative electrode sheet 1 of the present application can be wound or laminated to form a secondary battery. Fig.10 The secondary battery 10 is formed by a winding method, and the Fig.10It can be seen that a negative electrode sheet 1 or a positive electrode sheet 2 is placed between two adjacent separators 3, and the negative electrode sheets 1 and the positive electrode sheets 2 are alternately arranged in sequence along the stacking direction (coordinate axis x direction). The number and size of the negative electrode sheets 1 and / or the positive electrode sheets 2 can be selected according to actual conditions, and this application will not be repeated. Figure 5 Only one winding method is illustrated in the figure, and other laminations or winding methods are within the protection scope of this application.

[0204] like Fig.11 As shown in the figure, the positive electrode sheet 2 includes a positive electrode current collector 4 and a positive electrode film layer 21 located on at least one side of the positive electrode current collector 4, wherein: Fig.11 It is shown that a positive electrode film layer 21 is arranged on the surface of either side of the positive electrode current collector 4, and the positive electrode film layer 21 can also be located on the two side surfaces of the positive electrode current collector 4. The formation method of the positive electrode film layer 21 on the surface of the positive electrode current collector 4 includes any conventional method in the art, such as coating, deposition, etc. The structure of the negative electrode plate of the present application remains the same as that of the positive electrode plate, and the present application will not be repeated here. Coating includes any one or more of roller coating, extrusion coating, blade coating and gravure coating. Deposition includes any one or more of physical deposition and chemical deposition.

[0205] In some embodiments, the current collector includes an organic supporting layer and a metal layer located on at least one side of the organic supporting layer.

[0206] like Fig.12 As shown, the current collector 4 includes an organic support layer 42 and a metal layer 41 located on one side of the organic support layer 42. Fig.12 The figure only shows that the metal layer is provided on one side of the surface.

[0207] The organic support layer of the present application has low thermal conductivity and good thermal insulation performance, which first reduces the probability of short circuit. Even if a short circuit occurs, the current collector designed by the present application can improve safety by cutting off the short circuit in a short time. At the same time, the organic support layer effectively supports the metal layer and ensures the overall strength of the current collector. The density of the organic support layer is lower than that of the metal, which improves the energy density of the battery by reducing the weight of the battery cell.

[0208] In the present application, the method of forming the metal layer on the mechanical support layer includes any one or more of mechanical rolling, bonding, vapor deposition, chemical plating and electroplating.

[0209] In some embodiments, the Young's modulus of the organic support layer is 1 GPa to 20 GPa, so that the organic support layer has appropriate rigidity and toughness.

[0210] The method for measuring the Young's modulus of the organic support layer of the present application includes any conventional method in the art, for example, cutting the organic support layer into 15mm×200mm samples, measuring the thickness h (μm) of the sample with a micrometer, and using a Gotech stretching machine to perform a tensile test at room temperature and pressure (25°C, 0.1MPa). Set the initial position so that the sample between the clamps is 50 mm long and the stretching speed is 5 mm / min. Record the tensile load L (N) and the equipment displacement y (mm) until the sample breaks, then calculate the stress ε (GPa) = L / (15×h), the strain η = y / 50, draw a stress-strain curve, and take the initial linear region of the curve. The slope of the curve is the Young's modulus.

[0211] In some embodiments, the organic support layer includes any one or more of a polymer material and a polymer composite material. The polymer material includes terephthalate, polyethylene, polypropylene, epoxy resin, polyamide, polyimide, polyester, polyolefin, polyacetylene, siloxane polymer, polyether, polyol, polysulfone, polysaccharide polymer, amino acid polymer, polysulfur nitride polymer, one or more of aromatic ring polymers, aromatic heterocyclic polymers, epoxy resin, phenolic resin, their derivatives, their cross-linked products and their copolymers.

[0212] In some embodiments, the polymer material includes one or more of polycaprolactam (commonly known as nylon 6), polyhexamethylene adipamide (commonly known as nylon 66), polyparaphenylene terephthalamide (PPTA), polymetaphenylene diamine (PMIA), and polyethylene terephthalate (PET). Or polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polycarbonate (PC), polyethylene (PE), polypropylene (PP), poly(propylene-ethylene) (PPE), polyvinyl alcohol (PVA), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTEE), polystyrene sulfonate (PSS), polyacetylene (PA), silicone rubber, polyoxymethylene (POM), polyphenylene ether (PPO), polyphenylene sulfide (PPS), polyethylene glycol (PEG), cellulose, starch, protein, polyphenylene, polypyrrole (PPy), polyaniline (PAN), polythiophene (PT), polypyridine (PPY), acrylonitrile-butadiene-styrene copolymer (ABS) and its derivatives, cross-linked products thereof, and copolymers thereof.

[0213] In some embodiments, the organic support layer may be a single layer or multiple layers.

[0214] In some embodiments, a protective layer is further provided on the surface of the metal layer away from the organic support layer, and the protective layer is used to improve the interface of the current collector to enhance the bonding force between the current collector and the active material layer.

[0215] The protective layer of the present application includes any one or more of a metal protective layer and a metal oxide protective layer; the metal oxide protective layer and the metal protective layer have high mechanical strength, strong corrosion resistance and large specific surface area. The metal oxide protective layer includes any one or more of aluminum oxide, cobalt oxide, nickel oxide and chromium oxide.

[0216] The protective layer of the present application may be formed by any one or more of vapor deposition, in-situ formation and coating methods.

[0217] In some embodiments, the positive electrode active material layer and the negative electrode active material layer are located on both sides of the same organic support layer.

[0218] like Fig.13 As shown in the figure, a first metal layer 41 ′ and a second metal layer 41 ″ are respectively disposed on two opposite surfaces of the organic support layer 42 , a negative electrode active material layer 11 is disposed on a surface of the first metal layer 41 ′ away from the organic support layer 42 , and a positive electrode active material layer 21 is disposed on a surface of the second metal layer 41 ″ away from the organic support layer 42 .

[0219] The design adopted in this application is beneficial to further improve the energy density of the battery.

[0220] Preparation method of current collector

[0221] Some embodiments of the present application disclose a method for preparing a current collector, comprising the following process:

[0222] providing a metal layer;

[0223] Masking and etching are performed on the surface of either side of the metal layer to form a metal substrate and a metal gate group;

[0224] preparing a flame retardant slurry;

[0225] Applying the flame retardant slurry into the grooves formed between adjacent metal bars;

[0226] The current collector is obtained by drying.

[0227] In some embodiments, preparing a flame retardant slurry comprises:

[0228] The flame retardant and the binder are mixed in a mass ratio of 9:1, added into deionized water, and stirred to form a slurry with a solid content of 45% to 55%.

[0229] The solid content here in the present application refers to the mass ratio of the slurry after drying in a certain way compared to the mass ratio before drying. The measurement method includes methods known in the art, such as: weigh 1 to 4 g of slurry, recorded as m1, place the slurry in an oven to dry (120°C / 4h), weigh the solid residue, recorded as m2, solid content = m2 / m1*100%.

[0230] In some embodiments, the slurry coated in the present application completely fills the grooves to better block adjacent metal bars.

[0231] In some embodiments, masking and etching include any conventional methods in the art.

[0232] In some embodiments, the current collector includes an organic support layer and a metal layer located on at least one side of the organic support layer. In these embodiments, the present application discloses that the metal layer is prepared on at least one side of the organic support layer by any one or more of bonding, vapor deposition, electroplating, chemical plating, etc.

[0233] [Positive electrode]

[0234] According to some embodiments of the present application, as described above, the positive electrode plate comprises a current collector and a positive electrode film layer located on at least one side of the current collector, wherein the positive electrode film layer comprises a positive electrode active material.

[0235] In some embodiments of the present application, the positive electrode active material of the present application includes but is not limited to one or a combination of two or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and olivine structure lithium phosphate; wherein the structural formula of the olivine structure lithium phosphate is: LiFe 1-x- y Mn x M y PO 4 , 0≤x≤1, 0≤y<1, 0≤x+y≤1, M contains one or a combination of two or more transition metal elements or non-transition metal elements other than Fe and Mn, and M preferably contains one or a combination of two or more of Cr, Mg, Ti, Al, Zn, W, Nb, and Zr.

[0236] In some embodiments, the positive electrode active material includes a lithium nickel cobalt manganese oxide layered oxide; the lithium nickel cobalt manganese oxide layered oxide has a chemical formula of Li t (Ni a Co b Mn c ) 1-d M d O 2-v A v ; M includes any one or more of Zr, Sr, B, Ti, Mg, Sn and Al; A represents an oxygen-doping element, and the oxygen-doping element includes any one or more of S, N, F, Cl, Br and I; t is 0.2~1.2; a≥0.5; 0<b<0.2; a+b+c=1, 0≤d≤0.1; 0≤v<0.2.

[0237] The nickel cobalt manganese oxide lithium layered oxide of the present application has a high capacity, but is prone to releasing a large amount of heat in a short period of time when the battery is short-circuited or overcharged. The active material combined with the current collector of the present application is beneficial to reducing the probability of the above-mentioned thermal runaway of the battery.

[0238] In some embodiments, the positive electrode active material is not limited to LiCoO 2 、LiNiO 2 、LiMnO 2 、LiMn 2 O 4 、LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (NCM111), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523), LiNi 0.6 CO 0.2 Mn 0.2 O 2 (NCM622), LiNi 0.8 CO 0.1 Mn 0.1 O 2 (NCM811), LiNi 0.85 CO 0.15 Al 0.05 O 2 、LiFePO 4 (LFP) and LiMnPO 4 One or more of the following.

[0239] According to some embodiments of the present application, the positive electrode film layer also includes a conductive agent, a binder, etc. The conductive agent includes but is not limited to one or more combinations of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon dots, carbon nanotubes, graphene and carbon nanofibers. The binder includes but is not limited to polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorine-containing acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc. One or more combinations. The positive electrode current collector in the present application can be a metal foil or a composite current collector, wherein the metal foil can be an aluminum foil, and the composite current collector can include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector can be formed by forming metal materials such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy on a polymer material substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0240] The method for forming the positive electrode film layer of the present application comprises mixing the above raw materials with a solvent (such as N-methylpyrrolidone) in a certain mass ratio to form a positive electrode slurry, and evenly coating the positive electrode slurry on both sides of the current collector; controlling the single-sided coating weight to be 0.25g-0.50g / 1540.25mm 2 After drying, the cold press is used to compact the material to a certain density (2.8 g / cm 3 ~3.4g / cm 3 ), that is, a positive electrode sheet including a positive electrode film layer is obtained.

[0241] [Negative electrode]

[0242] The negative electrode plate of the present application includes a current collector and a negative electrode film layer located on one side surface or both sides surface of the current collector.

[0243] The present application discloses in some embodiments that the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes one or more of a carbonaceous material, a silicon-based material, a silicon-carbon composite material, a tin-based material and its alloy material. The carbonaceous material in the present application includes one or a combination of two or more of artificial graphite, natural graphite, soft carbon and hard carbon. Among them, artificial graphite, natural graphite, soft carbon, hard carbon, etc. include materials of any form conventional in the art, and include any conventional manufacturers and models in the art. The silicon-based material in the present application includes one or two of silicon-oxygen materials or silicon-carbon materials, or silicon-carbon composites. The tin-based and its alloy materials in the present application include but are not limited to Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO 2 The present application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for lithium ion batteries or sodium ion batteries can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0244] The present application discloses in some embodiments that the conductive agent comprises one or more of a point-shaped conductive agent, a linear conductive agent, and a planar conductive agent, wherein the point-shaped conductive agent comprises one or more of conductive carbon black (Super P or Super S), acetylene black, conductive graphite (KS-6 or KS-15 or SFG-6 or SFG-15), and Ketjen black, the linear conductive agent comprises one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanofibers, and the planar conductive agent comprises but is not limited to graphene.

[0245] The present application discloses in some embodiments that the negative electrode film layer includes a binder and a dispersant, etc. The binder includes but is not limited to polyvinyl alcohol, polyethylene glycol, sodium carboxymethyl cellulose, polyethylene oxide, polyacrylic acid, polyacrylamide, sodium alginate, styrene-butadiene rubber (SBR), etc. The dispersant also includes any conventional type in the art, such as cellulose and its salts, specifically including but not limited to methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, etc.

[0246] The method for forming the negative electrode film layer of the present application includes mixing the above-mentioned raw materials with a solvent (such as deionized water) in a certain mass ratio to form a negative electrode slurry, defoaming the negative electrode slurry, and then evenly coating the negative electrode slurry on both sides of the negative electrode collector; controlling the single-sided coating weight; drying, and compacting to a certain compaction density using a cold press to obtain a negative electrode sheet containing a negative electrode film layer.

[0247] [Isolator]

[0248] Some embodiments of the present application disclose an isolating element. The present application has no particular limitation on the type of isolating element, and any known porous isolating element with good chemical stability and mechanical stability can be selected.

[0249] In some embodiments, the isolation member includes a base material layer and a coating disposed on the surface of the base material layer; the base material of the base material layer includes one or more of polyethylene, polypropylene, poly(p-phenylene terephthalamide), polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide and polyamide; the coating includes a ceramic coating and / or a polymer coating. The base material layer has a good transmittance to lithium ions, which is conducive to the migration of lithium ions; the surface of the base material layer is provided with a coating, and the coating can further improve the mechanical properties of the isolation membrane. Furthermore, the ceramic particles in the ceramic coating include SiO 2 、Al 2 O 3 、AlOOH、CaO、TiO 2 ,MgO,ZnO,ZrO 2 Mg(OH) 2 and BaSO 4 One or more of the above. The ceramic coating of the present application plays an insulating role, reducing the probability of short circuit caused by puncturing the separator. That is, the present application uses a separator containing a ceramic coating, which first reduces the probability of short circuit. Even if a short circuit occurs, the current collector designed by the present application can improve safety by cutting off the short circuit in a short time.

[0250] In some embodiments, the polymer material of the polymer coating includes one or more of polyethylene (PE), polypropylene (PP), polyphenylene terephthalamide (PPTA), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyacrylonitrile (PAN), polyimide (PI) and polyamide (PA). The polymer coating and the base material layer can be made of the same or different materials, and the thickness of the polymer coating and the base material layer can be different. Further, the thickness of the polymer coating is less than the thickness of the base material layer.

[0251] In other embodiments, the material of the spacer can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The spacer can be a single-layer film or a multi-layer composite film, without particular limitation. When the spacer is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0252] [Electrolytes]

[0253] In some embodiments of the present application, an electrolyte is disclosed. The electrolyte of the present application may be in a liquid state, a solid state, or a gel state. Among them, the solid state is a solid electrolyte, the liquid state is a liquid electrolyte, and the gel state is a gel electrolyte. The lithium-ion battery of the present application uses a liquid electrolyte, that is, an electrolyte. The electrolyte contains an electrolyte salt and an organic solvent. Among them, the types of electrolyte salts include any conventional types in the art, for example, including but not limited to inorganic metal salts, such as RClO 4 , RAsF 6 、RPF 6 , RBF 4 ,RSbF 6 、RSO 3 F、RN(FSO 2 ) 2 etc.; fluorine-containing organic metal salts, such as RCF 3 SO 3 , RN(FSO 2 )(CF 3 SO 2 )、RN(CF 3 SO 2 ) 2 RN(C 2 F 5 SO 2 ) 2 、Cyclic 1,3-hexafluoropropane disulfonyl imide lithium、Cyclic 1,2-tetrafluoroethane disulfonyl imide lithium、RN(CF 3 SO 2 )(C 4 F 9 SO 2 )、RC(CF 3 SO 2 ) 3 、RPF 4 (CF 3 ) 2 、RPF 4 (C 2 F 5 ) 2 、RPF 4 (CF 3 SO 2 ) 2 、RPF 4 (C 2 F 5 SO 2 ) 2 , RBF 2 (CF 3 ) 2 , RBF 2 (C 2 F 5 )2 , RBF 2 (CF 3 SO 2 ) 2 , RBF 2 (C 2 F 5 SO 2 ) 2 and metal salts containing dicarboxylic acid complexes, such as lithium bis(oxalato)borate, lithium difluorooxalatoborate, lithium tri(oxalato)phosphate, lithium difluorobis(oxalato)phosphate, lithium tetrafluoro(oxalato)phosphate, etc. The metal and R herein both contain lithium ions.

[0254] According to some embodiments of the present application, the concentration of the electrolyte salt in the electrolyte is 0.1mol / L to 4mol / L. The present application discloses in these embodiments that the concentration of the electrolyte salt is 0.1mol / L, 0.2mol / L, 0.3mol / L, 0.4mol / L, 0.5mol / L, 0.6mol / L, 0.7mol / L, 0.8mol / L, 0.9mol / L, 1mol / L, 1.2mol / L, 1.5mol / L, 1.8mol / L, 2mol / L, 2.2mol / L, 2.5mol / L, 2.8mol / L, 3mol / L, 3.2mol / L, 3.5mol / L, 3.8mol / L, 4mol / L, or any one of the values ​​satisfying the above range.

[0255] As described above, the organic solvent includes any one or more of carboxylic acid ester compounds, carbonate compounds, and ether compounds. Among them, the carboxylic acid ester compounds include one or more of ethyl acetate (EA), methyl acetate (MA), ethyl propionate (EP), propyl acetate (PA), methyl propionate (MP), methyl butyrate (MB), ethyl butyrate (EB), and 1,4-butyrolactone (GBL); the carbonate compounds include one or more of ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), and fluoroethylene carbonate (FEC). The ether compounds include at least one of tetrahydrofuran, dimethyltetrahydrofuran, tetrahydropyran, dimethyltetrahydropyran, 1,2-dimethoxyethane, dipropylene glycol dimethyl ether, or dimethyl phthalate. The organic solvent of the present application further comprises one or two of nitrile solvents and sulfone solvents, wherein the nitrile solvent comprises one or more of acetonitrile (AN), glutaronitrile (GLN) and adiponitrile (ADN). The sulfone solvent comprises at least one or a combination of two of sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl sulfone (ESE).

[0256] According to some embodiments of the present application, the electrolyte further comprises a film-forming stabilizer, which comprises a positive electrode film-forming stabilizer and a negative electrode film-forming stabilizer, wherein the positive electrode film-forming stabilizer comprises carbonate additives and / or sulfate additives, and the carbonate additives include one or more of vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), vinyl ethylene carbonate (VEC) and dioctyl carbonate (CC). Sulfate additives include cyclic sulfonate additives and / or alkyl sulfate additives; further, cyclic sulfonate additives include one or more of 1,3-propane sultone (PS), propylene sultone (PES), and 3-fluoro-1,3-propane sultone (FPS); alkyl sulfate additives include one or more of vinyl sulfate (DTD), diethyl sulfate (DES) and dimethyl sulfate (DMS). The negative electrode film-forming stabilizer includes one or more of boron lithium salts, phosphorus-containing lithium salts and sulfur-containing lithium salts; the boron-containing lithium salt includes lithium tetrafluoroborate (LiBF 4 ), lithium bis(oxalatoborate) (LiBOB) and lithium bis(fluorooxalatoborate) (LiDFOB); phosphorus-containing lithium salts include lithium difluorophosphate (LiPO 2 F 2 ), lithium fluorophosphate (Li 2 PO 3 F) and lithium phosphate (Li 3 PO4 ) or more. Sulfur-containing lithium salts include lithium fluorosulfonate (LiFSO 3 ), lithium sulfate (Li 2 SO 4 ), lithium sulfamate (LiSO 3 NH 2 )

[0257] In some embodiments, the above-mentioned electrolyte also includes an ionic liquid additive, the cation of which includes any one or more of nitrogen-containing onium ions and phosphonium-containing onium ions, and the anion of which includes any one or more of halogen ions, phosphate ions, borate ions, and sulfonyl imide anions.

[0258] In this application, the electrolyte is the carrier of ion transmission in the battery, and plays the role of conducting ions between the positive and negative electrodes of the battery. The type of electrolyte affects the safety of the battery. Ionic liquid additives refer to salts that are added to the electrolyte in a relatively small amount, are completely composed of cations and anions, and are liquid at room temperature or near room temperature, where room temperature refers to 25°C ± 5°C. Ionic liquid additives themselves have high thermal stability and low volatility. At the same time, the ionic liquid additives can also improve the stability of the negative electrode active material by forming a solid electrolyte interface film (SEI) and improving the stability of the film, thereby improving the safety of the battery.

[0259] In some embodiments, the cation of the ionic liquid additive comprises 1-butyl-3-methylimidazolium ([Bmin] + )、1-benzyl-3-methylimidazolium ([Bzmin] + ), 3-methyl-1-ethoxycarbonylmethylimidazolium ([Etmim] + )、1-alkyl-3-methylimidazolium ([Cnmim] + ), 1-[(trimethylsilyl)methyl]benzotriazolium ([SiMBIM] + )、N-alkyl-N-methylpiperidinium ([CnC1pip] + ), 5-azoniaspiro[4.4]nonane ([AS[mn]] + ), trihexyl(tetradecyl)phosphine ion ([Tf2N] + ), tetrabutylphosphine ion ([Pnnnn] + ), n-butyl-N-methylpyrrolidinium ([Pyr 14 ] + ) can be one or more of tetrabutylphosphine ion or n-butyl-N-methylpyrrolidinium.

[0260] In some embodiments, the anion of the ionic liquid additive comprises a chloride ion ([Cl] - ), bromide ion ([Br] - ), iodide ion ([I] - ), hexafluorophosphate ([PF 6 ] - ), tetrafluoroborate ([BF 4 ] - ), dicyandiamide anion ([N(CN) 2 ] - ), bis(fluorosulfonyl)imide anion ([FSI] - ), bis(trifluoromethylsulfonyl)imide ([TFSI] - ) can be one or more of hexafluorophosphate or bis(fluorosulfonyl)imide anions.

[0261] In some embodiments, the ionic liquid additive includes one or more of tetrabutylphosphine hexafluorophosphate, tetrabutylphosphine bis(fluorosulfonyl)imide, n-butyl-N-methylpyrrolidine hexafluorophosphate, n-butyl-N-methylpyrrolidine bis(fluorosulfonyl)imide, 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-benzyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-benzyl-3-methylimidazolium bis(fluorosulfonyl)imide, and can be selected from tetrabutylphosphine hexafluorophosphate, tetrabutylphosphine bis(fluorosulfonyl)imide, n-butyl-N-methylpyrrolidine hexafluorophosphate, and n-butyl-N-methylpyrrolidine bis(fluorosulfonyl)imide.

[0262] The secondary battery of the present application will be described in detail below in conjunction with specific embodiments.

[0263] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods.

[0264] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0265] Conventional techniques of inorganic chemistry within the art can be used in this application. In the following examples, efforts are made to ensure the accuracy of the numbers used (including amounts, temperatures, reaction times, etc.), but some experimental errors and deviations should be considered. The temperatures (in degrees Celsius) used in the following examples are expressed in ° C, and the pressure is atmospheric pressure or near atmospheric pressure. All pharmaceutical reagents are purchased at AR grade, and all reactions are carried out under argon protection. Unless otherwise noted, all reagents are obtained from commercial channels.

[0266] Experimental materials:

[0267] The positive electrode active material, the negative electrode active material, the metal and the flame retardant are all commercially available.

[0268] Preparation Example 1

[0269] A method for preparing a current collector is provided, the method comprising the following steps:

[0270] S100, providing an organic support layer (Young's modulus is 4 GPa, thickness is 5 μm), and cleaning the organic support layer by acid washing, alkali washing, etc.;

[0271] S200, placing the cleaned organic support layer in a vacuum evaporation chamber, and depositing metallic copper on a single side surface of the organic support layer in a thickness direction at a high temperature of 1300° C. to 2000° C. to form a copper metal layer with a thickness of 5 μm; similarly, replacing metallic copper with metallic aluminum to form an aluminum metal layer with a thickness of 5 μm (H=5 μm);

[0272] S300, using a mask and laser etching, etching a groove and a metal grid on the metal layer, wherein the depth of the groove is 1.5 μm (h=1.5 μm, h / H=30%), the width of the metal grid is 20 μm (y=20 μm), and the distance between two adjacent metal grids is 200 μm (x=200 μm, y / x=10%);

[0273] S400, adding flame retardant phosphonate (bisphenol A bis(triphenyl phosphate)) and polyacrylate (polymethyl acrylate) binder into deionized water in a weight ratio of 9:1, and stirring in a high-speed stirrer to obtain a uniformly dispersed slurry, wherein the solid content of the slurry is 50wt.%;

[0274] S500, coating the above slurry in the grooves formed between adjacent metal bars and completely filling the grooves, placing in a vacuum dryer at 50° C. for 12 hours, to obtain a positive electrode current collector (copper) and a negative electrode current collector (aluminum).

[0275] Preparation Example 2

[0276] A method for preparing a negative electrode current collector (copper) is provided. The method is different from the above-mentioned Preparation Example 1 in that the method does not contain an organic support layer.

[0277] Preparation Example 3-1

[0278] A method for preparing a negative electrode current collector (copper) is provided. The method is different from the above-mentioned Preparation Example 1 in that the width of the metal grid is adjusted to 100 μm so that y / x=50%, and the rest remains the same as Preparation Example 1.

[0279] Preparation Example 3-2

[0280] A method for preparing a negative electrode current collector (copper) is provided. The method is different from the above-mentioned Preparation Example 1 in that the width of the metal grid is adjusted to 180 μm so that y / x=90%, and the rest remains the same as Preparation Example 1.

[0281] Preparation Example 4-1

[0282] A method for preparing a negative electrode current collector (copper) is provided. The method is different from the above-mentioned Preparation Example 1 in that the depth of the groove is adjusted to 2.5 μm so that h / H=50%, and the rest is the same as Preparation Example 1.

[0283] Preparation Example 4-2

[0284] A method for preparing a negative electrode current collector (copper) is provided. The method is different from the above-mentioned Preparation Example 4-1 in that the width of the metal grid is adjusted to 100 μm so that y / x=50%, and the rest remains the same as Preparation Example 4-1.

[0285] Preparation Example 4-3

[0286] A method for preparing a negative electrode current collector (copper) is provided. The method is different from the above-mentioned Preparation Example 4-1 in that the width of the metal grid is adjusted to 180 μm so that y / x=90%, and the rest remains the same as Preparation Example 4-1.

[0287] Preparation Example 5-1

[0288] A method for preparing a negative electrode current collector (copper) is provided. The method is different from the above-mentioned Preparation Example 1 in that the depth of the groove is adjusted to 3.5 μm so that h / H=70%, and the rest is the same as Preparation Example 1.

[0289] Preparation Example 5-2

[0290] A method for preparing a negative electrode current collector (copper) is provided. The method is different from the above-mentioned Preparation Example 5-1 in that the width of the metal grid is adjusted to 100 μm so that y / x=50%, and the rest remains the same as Preparation Example 5-1.

[0291] Preparation Example 5-3

[0292] A method for preparing a negative electrode current collector (copper) is provided. The method is different from the above-mentioned Preparation Example 5-1 in that the width of the metal grid is adjusted to 180 μm so that y / x=90%, and the rest remains the same as Preparation Example 5-1.

[0293] Preparation Example 6-1

[0294] A method for preparing a current collector is provided. The method is different from the above-mentioned Preparation Example 1 in that the flame retardant phosphonate (bisphenol A bis(triphenyl phosphate)) of the flame retardant is replaced with calcium metaborate, and the rest is the same as Preparation Example 1.

[0295] Comparative Preparation Example 1

[0296] A method for preparing a current collector is provided. The method is different from the above-mentioned Preparation Example 1 in that no metal grid and flame retardant are provided, and the rest is the same as Preparation Example 1.

[0297] Test the overload capacity of the current collector:

[0298] The current collector prepared in the above preparation example was cut into pieces with an area of ​​10*10cm 2 The current collector sample is a metal foil with the same thickness and material as the metal layer on the side of the metal grid away from the metal layer. The 10*10cm 2 The amount of electricity on the current collector. Use a DC voltage-stabilized current power supply, connect the positive electrode to the metal layer of the current collector, and the negative electrode to the metal foil covered by the metal grid. Pass 1C, 3C, 6C, and 10C of electricity respectively. Observe the fusing of the metal grid on the current collector within 30 minutes. Cut off the power supply in time when the fusing occurs. Record the time and current of the fusing. The following table 1-1 is obtained:

[0299] Table 1-1 Performance list of current collector

[0300]

[0301]

[0302] From the above-mentioned overload capacity test of the current collector, it can be seen that as the thickness and width of the metal grid increase, the larger the current and the longer the time required for the metal grid to melt, which indicates that the metal grid as a "fuse" has a larger fuse current. But in fact, a metal grid with too large or too small a fuse current is not suitable for the battery. Because too large a fuse current means that even the current during a short circuit may not be able to melt the metal grid, so it will not be able to cut off the circuit in time to prevent thermal runaway; but too small a fuse current is also not good for some batteries that require high-power charging and discharging. This is because the current of high-power charging and discharging generally reaches about 3C. If the metal grid has melted at 1C, it is bound to cause some active materials to be unable to participate in the normal battery cycle, which will cause the polarization to increase, causing the battery to undergo lithium deposition and causing the battery capacity to drop sharply. Therefore, the present application can flexibly adjust the size of the metal grid according to the type of positive electrode active material of the battery and the performance requirements of the battery.

[0303] Test the thermal conductivity of the current collector:

[0304] The current collector prepared in the above preparation example was placed in a sample of 5 cm×5 cm, and the thermal conductivity of the sample was measured using a TC3000 thermal conductivity meter.

[0305] Table 1-2 Performance list of current collector

[0306] Serial number Thermal conductivity Preparation Example 1 0.3W / (m·K) Preparation Example 2 300W / (m·K) Preparation Example 6-1 0.1W / (m·K) Comparative Preparation Example 1 8W / (m·K)

[0307] As can be seen from Table 1-2, the flame retardant designed in the current collector of this application has a certain heat absorption and heat resistance effect. At the same time, the organic support layer designed in the current collector of this application has a more obvious flame retardant effect than the flame retardant.

[0308] Example 1

[0309] A method for preparing a battery cell is provided, comprising the following preparation process:

[0310] In step S200 of Preparation Example 1, metallic copper is deposited on both side surfaces of the organic support layer in the thickness direction, and the rest is the same as Preparation Example 1 to form a positive electrode current collector (copper) and a negative electrode current collector (aluminum) with a thickness of 15 μm respectively.

[0311] Preparation of positive electrode sheet:

[0312] Take the ternary material LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), conductive carbon black, and PVDF were mixed in a ratio of 96.5:2.5:1, and nitrogen methyl pyrrolidone solvent was added and stirred to form a positive electrode slurry with a solid content of 60%. The positive electrode slurry was coated on both surfaces of the positive electrode current collector aluminum foil, and heated and dried. Specifically, a multi-section oven was used, and the temperature settings were 120°C / 100°C / 90°C, and then a cold press was used for compaction to obtain a positive electrode film layer with a compaction density of 2.8g / cm 3 .

[0313] Preparation of negative electrode sheet:

[0314] Artificial graphite, conductive acetylene black, stabilizer carboxymethyl cellulose and binder SBR were dispersed in deionized water in a mass ratio of 95:1.0:1.5:2.5 to form a negative electrode slurry. The negative electrode slurry was evenly coated on both sides of the negative electrode current collector copper foil. The nine-section oven was set at 100℃ / 100℃ / 95℃ / 85℃ / 85℃ / 80℃ / 80℃ / 80℃ / 60℃ for drying, and then compacted using a cold press. The compaction density of the negative electrode film layer was 1.65g / cm 3 .

[0315] Isolators available:

[0316] A porous polyethylene (PE) film with a thickness of 13 μm was used as the separator.

[0317] Provides electrolytes:

[0318] In an argon atmosphere glove box with a water content of <10 ppm, EC (ethylene carbonate), PC (polycarbonate), and DMC (dimethyl carbonate) were mixed at a weight ratio of EC:PC:DMC=3:3:3, and then LiPF 6 , VC, DTD and PS, after stirring evenly, an electrolyte solution is obtained, in which LiPF 6 The concentration of the lithium ion battery electrolyte is 1 mol / L, and the mass percentages of VC, DTD, and PS are 3%, 1%, and 1%, respectively, to obtain an electrolyte.

[0319] Assembling battery cells:

[0320] The positive electrode sheet, separator and negative electrode sheet are wound in sequence, so that the separator is placed between the positive electrode sheet and the negative electrode sheet to play an isolating role, and the corresponding assembly forms a wound bare battery cell; the wound bare battery cell is placed in an outer packaging shell, and after drying, the electrolyte is injected, and after vacuum packaging, standing, forming, shaping and other processes, a battery cell is obtained.

[0321] Example 2

[0322] A method for preparing a battery cell is provided. The difference between Example 2 and Example 1 is that the positive electrode collector (copper) and the negative electrode collector (aluminum) are replaced with the positive electrode collector and the negative electrode collector of Preparation Example 2, and the rest remain the same as Example 1.

[0323] Example 3-1

[0324] A method for preparing a battery cell is provided. The difference between Example 3-1 and Example 1 is that the positive electrode collector (copper) and the negative electrode collector (aluminum) are replaced with the positive electrode collector and the negative electrode collector of Preparation Example 3-1, and the rest remains the same as Example 1.

[0325] Example 4-1

[0326] A method for preparing a battery cell is provided. The difference between Example 4-1 and Example 1 is that the positive electrode collector (copper) and the negative electrode collector (aluminum) are replaced with the positive electrode collector and the negative electrode collector of Preparation Example 4-1, and the rest remains the same as Example 1.

[0327] Example 5-1

[0328] A method for preparing a battery cell is provided. The difference between Example 5-1 and Example 1 is that the positive electrode collector (copper) and the negative electrode collector (aluminum) are replaced with the positive electrode collector and the negative electrode collector of Preparation Example 5-1, and the rest remains the same as Example 1.

[0329] Example 6-1

[0330] A method for preparing a battery cell is provided. The difference between Example 6-1 and Example 1 is that the positive electrode collector (copper) and the negative electrode collector (aluminum) are replaced with the positive electrode collector and the negative electrode collector of Preparation Example 6-1, and the rest remains the same as Example 1.

[0331] Example 7-1

[0332] A method for preparing a battery cell is provided. The difference between Example 7-1 and Example 1 is that the positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) replaced by LiNi 0.9 Co 0.05 Mn 0.05 O 2 , the rest remain the same as in Example 1.

[0333] Example 8-1

[0334] A method for preparing a battery cell is provided. The difference between Example 8-1 and Example 1 is that: the isolation member is selected: a porous polyethylene (PE) film (13 μm) is used as the base film, and an aluminum oxide coating (single-side thickness is 1.5 μm) is formed on both sides of the base film. The rest remains the same as Example 1.

[0335] Example 9-1

[0336] A method for preparing a battery monomer is provided. The difference between Example 9-1 and Example 1 is that tetrabutylphosphine hexafluorophosphate is further added to the electrolyte with a mass percentage of 0.1%, and the rest is the same as Example 1.

[0337] Example 10-1

[0338] A method for preparing a battery cell is provided. The difference between Example 10-1 and Example 1 is that a positive electrode film layer and a negative electrode film layer are formed on both sides of the current collector, respectively. Fig.13 The other aspects are the same as those of Example 1.

[0339] Comparative Example 1

[0340] A method for preparing a battery monomer is provided. The difference between comparative example 1 and example 1 is that the positive electrode collector (copper) and the negative electrode collector (aluminum) are replaced with the positive electrode collector and the negative electrode collector of comparative preparation example 1, and the rest remain the same as example 1.

[0341] In addition to the overload capacity test of the current collector, the present application also conducts high-rate charge and discharge cycle tests on the battery cells to explore the cycle life at different rates.

[0342] High rate charge and discharge cycle test of battery cells:

[0343] The specific test process of this experiment is as follows: first, the battery prepared in the embodiment and comparative example of the present application is discharged to 2.5V (the voltage of the ternary lithium-ion battery when the SOC is 0%) at a current of 0.33C, and then the battery is charged to 4.4V (the voltage of the ternary lithium-ion battery when the SOC is 100%) at a current of 1C; finally, it is discharged to 2.5V at 0.33C, and the discharge specific capacity C of the battery is recorded at this time. 0 ; Then charge the battery to 4.4V at 1C, 3C, 6C, and 10C respectively, and then discharge it to 2.5V at 0.33C, and repeat this cycle for 10cls. During the cycle, monitor whether the maximum temperature of the battery surface is greater than 150℃ (the monitoring method includes connecting a temperature sensor on the battery surface), and record the discharge capacity of the last cycle as C 1 , the cycle performance at this time = C 1 / C 0 *100%. The test results are as follows:

[0344] Table 2 Performance of battery cells

[0345]

[0346]

[0347] It can be seen from Table 2 that, compared with Comparative Example 1, the design method provided in the embodiment of the present application is conducive to reducing the surface temperature of the battery.

[0348] In combination with Example 1, Example 2 and Example 10-1 of the present application, it can be seen that the design of the positive electrode active material layer and the negative electrode active material layer being located on both side surfaces of the same organic support layer is conducive to improving the battery energy density and thus improving the battery cycle life.

[0349] To sum up, when a short circuit occurs in the battery cell provided by the present application, the flame retardant located between the metal bars can absorb part of the heat generated by the short circuit to cool the battery cell, and when the short circuit current is large enough, the instantaneous overload of electrons will cause the connected metal bars to melt, thereby preventing the short circuit from continuing to occur and disconnecting the circuit, reducing the probability of thermal runaway when a short circuit occurs in the battery.

[0350] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: It includes a current collector and an active material layer located on at least one side of the current collector; The current collector includes a metal layer; The metal layer includes a metal substrate and a metal grid group located on at least one side surface of the metal substrate; The metal grid group includes metal grid bars; The metal bars extend along a first direction and are arranged at intervals in a second direction; the first direction is different from the second direction; A groove is formed between adjacent metal bars, and a flame retardant is arranged in the groove; The orthographic projection of the flame retardant and the metal grid assembly on the metal base overlaps with the metal base.

2. The battery cell according to claim 1, characterized in that: The first direction and the second direction form an angle α, 0°<α≤90°.

3. The battery cell according to any one of claims 1 to 2, characterized in that: Along the third direction, the metal layer includes a first surface and a second surface that are arranged opposite to each other, and a distance between the first surface and the second surface is H; Along the third direction, the metal grid includes an A surface and a B surface that are arranged opposite to each other, and the distance between the A surface and the B surface is h; Satisfy: 0.1≤h / H≤0.9; The third direction is different from both the first direction and the second direction.

4. The battery cell according to claim 3, characterized in that: An angle formed by the third direction and the first direction is 90°, and an angle formed by the third direction and the second direction is 90°.

5. The battery cell according to any one of claims 1 to 4, characterized in that: The metal grid group includes a first metal grid bar and a second metal grid bar that are adjacently arranged; Along the second direction, the first metal grid includes a C surface and a D surface that are arranged opposite to each other; The second metal grid comprises a C' surface and a D' surface which are arranged opposite to each other, wherein the C' surface is arranged close to the D surface, and the D' surface is arranged far away from the D surface; The distance between the C surface and the D surface is y; The distance between the C surface and the C' surface is x; Satisfies: 0.1≤y / x≤0.

9.

6. The battery cell according to any one of claims 1 to 4, characterized in that: The thermal conductivity of the current collector is 0.01 W / (K·m) to 500 W / (K·m).

7. The battery cell according to any one of claims 1 to 6, characterized in that: The active material layer includes a positive electrode active material layer; The positive electrode active material layer includes a positive electrode active material; The positive electrode active material includes a lithium nickel cobalt manganese oxide layered oxide; The chemical formula of the lithium nickel cobalt manganese oxide layered oxide is Li t (Ni a Co b Mn c ) 1-d M d O 2-v A v ; M includes any one or more of Zr, Sr, B, Ti, Mg, Sn and Al; A represents an oxygen doping element, and the oxygen doping element includes any one or more of S, N, F, Cl, Br and I; t is 0.2 to 1.2; a≥0.5； 0<b<0.2;a+b+c=1, 0≤d≤0.1； 0≤v＜0.2。 8. The battery cell according to any one of claims 1 to 7, characterized in that: The battery cell includes a separator; The isolation element comprises a substrate and a coating located on at least one surface of the substrate, wherein the coating comprises any one or more of an organic coating and an inorganic coating.

9. The battery cell according to any one of claims 1 to 8, characterized in that: The battery cell includes an electrolyte; The electrolyte includes an ionic liquid additive, wherein the cation of the ionic liquid additive includes any one or more of nitrogen-containing onium ions and phosphonium-containing onium ions, and the anion of the ionic liquid additive includes any one or more of halogen ions, phosphate ions, borate ions, and sulfonyl imide anions.

10. The battery cell according to any one of claims 1 to 9, characterized in that: The metal substrate and the metal grid group include any one or more of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, iron, iron alloy, titanium, titanium alloy, silver and silver alloy; and / or; The flame retardant comprises any one or more of an organic flame retardant and an inorganic flame retardant.

11. The battery cell according to claim 10, characterized in that: The organic flame retardant includes any one or more of phosphonates, dicyclopentadiene, aliphatic halogenated hydrocarbons, aromatic halogenated compounds, and nitrogen series; The inorganic flame retardant includes any one or more of expanded graphite, metal hydroxide, boron salt and phosphate.

12. The battery cell according to any one of claims 1 to 11, characterized in that: The current collector comprises an organic support layer and a metal layer located on at least one side of the surface of the organic support layer.

13. The battery cell according to any one of claims 1 to 12, characterized in that: The current collector includes an organic support layer, and a first metal layer and a second metal layer respectively located on both side surfaces of the organic support layer; A negative electrode active material layer is provided on a surface of the first metal layer away from the organic support layer; A positive electrode active material layer is disposed on a surface of the second metal layer away from the organic support layer.

14. A current collector, characterized in that: including a metal layer; The metal layer includes a metal substrate and a metal grid group located on at least one side surface of the metal substrate; The metal grid group includes metal grid bars; The metal bars extend along a first direction and are arranged at intervals in a second direction; the first direction is different from the second direction; A groove is formed between adjacent metal bars, and a flame retardant is arranged in the groove; The orthographic projection of the flame retardant and the metal grid assembly on the metal base overlaps with the metal base.

15. A method for preparing the current collector according to claim 14, characterized in that: The process includes the following: providing a metal layer; Masking and etching are performed on the surface of either side of the metal layer to form a metal substrate and a metal gate group; preparing a flame retardant slurry; Applying the flame retardant slurry into the grooves formed between adjacent metal bars; The current collector is obtained by drying.

16. The preparation method according to claim 15, characterized in that: The preparation of flame retardant slurry includes: The flame retardant and the binder are mixed in a mass ratio of 9:1, added into deionized water, and stirred to form a slurry with a solid content of 45% to 55%.

17. A battery device, characterized in that: A battery cell comprising the battery cell according to any one of claims 1 to 13.

18. An electrical device, characterized in that: A battery device comprising the battery device of claim 17.

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