Current collector, method for preparing current collector, battery cell, battery device and power-consuming device

Abstract

The present application belongs to the field of battery technology and specifically discloses a current collector, a method for preparing the current collector, a battery cell, a battery device, and an electrical device. The battery cell provided by the present application includes a 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 battery cell provided by the present application reduces the probability of further thermal runaway in the event of a short circuit in the battery.

Description

Technical Field

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

[0002] With the development of new energy technologies, batteries are being used in more and more applications, such as in mobile phones, laptops, electric vehicles, electric cars, energy storage devices, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools. This places increasingly higher demands 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 electrical 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 of the current collector;

[0005] The current collector includes a metal layer;

[0006] The metal layer includes 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 provided in the groove;

[0010] The orthographic projections of the flame retardant component 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 the electrons will cause the connected metal bars to melt, thereby preventing the short circuit from continuing 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, where 0°<α≤90°.

[0013] 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 angle formed between the two satisfies the above range, which facilitates the arrangement of the metal bars.

[0014] In some embodiments, along the third direction, the metal layer includes a first surface and a second surface disposed opposite to each other, 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 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 this application, 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 melt 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 this application, the functions of the above-mentioned different stages can be well exerted.

[0019] In some embodiments, the angle formed by the third direction and the first direction is 90°, and the 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 and a second metal grid disposed adjacent to each other;

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

[0022] The second metal grid includes a C' surface and a D' surface that are arranged opposite to each other, wherein the C' surface is arranged close to the D surface, and the D' surface is arranged 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, this application requires that when a battery short circuit occurs, the metal bars fuse due to a momentary electronic overload. The flame retardant must not only separate adjacent metal bars but also achieve good heat absorption and insulation. Therefore, this application requires limiting the width of the metal bars and flame retardant in the second direction. This application selects values ​​within the above range to facilitate the above functions.

[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 lithium nickel cobalt manganate 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, wherein 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 impose any special restrictions 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 releasing 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 battery experiencing the above-mentioned thermal runaway.

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

[0040] The above-mentioned isolation element includes a substrate and a coating located on at least one side of the substrate, and the coating includes any one or more of an organic coating and an inorganic coating.

[0041] The organic or inorganic coating in this application acts as an insulator, reducing the probability of a short circuit caused by puncturing the separator. In other words, the use of a separator containing a coating in this application first reduces the probability of a short circuit. Even if a short circuit occurs, the current collector designed in this application can quickly shut off the short circuit, improving safety.

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

[0043] 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 phosphorus-containing onium ions, and the anion of the ionic liquid additive includes 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 component includes 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 halides, 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 side of the 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 sides 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 includes 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 provided in the groove;

[0058] The orthographic projections of the flame retardant component 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 steps:

[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 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 skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to denote the same components. In the drawings:

[0071] Figure 1 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 according to some embodiments of the present application;

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

[0074] Figure 4 This is a schematic structural diagram of a battery pack according to some embodiments of the present application;

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

[0076] Figure 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] Figure 11 This is a schematic structural diagram of the positive electrode sheet of some embodiments of the present application;

[0078] Figure 12 This is a schematic structural diagram of another current collector according to some embodiments of the present application;

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

[0080] The accompanying drawings in the specific implementation manner are as follows:

[0081] 10000, vehicle;

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

[0083] 100. Battery cell;

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

[0085] 10. Secondary batteries;

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

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

[0088] 2. Positive electrode sheet; 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; 41b1-1, first metal grid;

[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 grids are arranged opposite to each other along the second direction;

[0099] Surface C' and surface D': 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] Second direction: the direction of metal grid arrangement, or the coordinate axis y direction;

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

[0103] Below, with appropriate reference to the accompanying drawings, the embodiments of the current collector, the method for preparing the current collector, the battery cell, the battery device, and the power device of the present application are described in detail. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be 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 description 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 "ranges" disclosed herein are defined in terms of lower and upper limits, where a given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner can be inclusive or exclusive and can be combined arbitrarily, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise indicated, the numerical range "a to b" is a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this 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] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating 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] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0109] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: 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] Unless 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 number, 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 pieces" refers to more than two pieces (including two pieces).

[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. They 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 device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the embodiments of the present application.

[0113] Batteries have been widely used in various products due to their advantages such as 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 preparation method of the current collector, a battery cell, a battery device and an electrical device.

[0115] First, 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 base and a metal grid group located on at least one side of the metal base; 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, and the orthographic projection of the flame retardant and the metal grid group on the metal base overlaps with the metal base.

[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 the electrons will cause the connected metal bars to melt, thereby preventing the short circuit from continuing 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 conducive to improving user experience.

[0118] Electrode assembly

[0119] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode sheet, a negative electrode sheet, and a separator, which is located between the negative and positive electrodes. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded in and released from the positive and negative electrodes. The separator, located between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing 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, parallel, or hybrid via a busbar.

[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 multiple battery cells to form an independent module. As an example, the battery module may be formed by bundling multiple battery cells with 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 housed 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 box by directly fixing the plurality of battery cells to the box.

[0127] As an example, the housing may include a first housing and a second housing. The first housing and the second housing engage to form an enclosed space within the housing to house the battery cell assembly. Enclosed here means covered or closed, and can be either sealed or unsealed. The first housing may be a top cover or a bottom plate.

[0128] As an example, the box may include a top cover, a frame, and a bottom plate, wherein the top cover and the bottom plate are respectively connected to the frame to form a closed space inside the box 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 cells of the present application may include outer packaging. The outer packaging may be used to encapsulate the electrode assembly and electrolyte composed of the battery cells. The outer packaging of the battery cells may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery cells may also be a soft shell, such as a bag-type soft shell. The material of the soft shell may be plastic, and the plastic includes but is not limited to polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0131] The present application has no particular restrictions on the shape of the battery, which can 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. 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 membrane 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 may 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, laptops, 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 structural diagram 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. 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. 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 serve as an operating power source for the vehicle 10000. The vehicle 10000 may further include a controller 2000 and a motor 3000. The controller 2000 is used to control the battery 1000 to power the motor 3000. For example, the controller 2000 is used to control the battery 1000 to power the motor 3000, for example, for starting, navigating and operating power requirements of the vehicle 10000 during driving.

[0136] In some embodiments of the present application, the battery 1000 can serve not only as an operating power source for the vehicle 10000, but also as a driving power source for 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 This is an exploded view of a battery 1000 provided in some embodiments of the present application. Battery 1000 includes a housing 200 and a battery cell 100. Conventional battery cells include primary or secondary batteries, but this application specifically protects secondary batteries 10. Battery cell 100 is housed within housing 200. Housing 200 is used to accommodate battery cell 100 and can adopt a variety of structures.

[0138] In some embodiments, the housing 200 may include a first portion 210 and a second portion 220. The first portion 210 and the second portion 220 overlap each other, and the first portion 210 and the second portion 220 together define a storage space for accommodating the battery cells 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. The first portion 210 overlaps the open side of the second portion 220, so that the first portion 210 and the second portion 220 together define the storage space. The first portion 210 and the second portion 220 may also be hollow structures with one end open, with the open side of the first portion 210 overlapping the open side of the second portion 220. Of course, the housing 200 formed by the first portion 210 and the second portion 220 can have various shapes, such as a cylinder, a rectangular parallelepiped, 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 hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 100. The multiple battery cells 100 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery 100 structure may be housed within the housing 200. Of course, the battery 1000 may also be a battery module formed by first connecting multiple battery cells 100 in series, in parallel, or in a hybrid connection, and then the multiple battery modules 1000 are further connected in series, in parallel, or in a hybrid connection to form an entire battery 1000 structure, and then housed within the housing 200. The battery 1000 may also include other structures, for example, the battery 1000 may also include a busbar component for electrically connecting the multiple battery cells 100.

[0140] battery cells

[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 base and a metal grid group located on at least one side of the metal base; 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 orthographic projection of the flame retardant and the metal grid group on the metal base overlaps with the metal base.

[0142] The battery cells of the present application may be secondary batteries, which are batteries that can be recharged to activate the active materials after discharge and continue to be used. The battery cells may be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, 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 that collects current, which can collect the current generated by the active material of the battery to form a larger current for external output, while its own internal resistance is sufficiently small.

[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 a schematic diagram of a metal grid group 41b provided on one side of the metal substrate 41a. The metal grid group 41b includes metal 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 provided in the groove 41c.

[0145] The flame retardant in this application refers to a flame-retardant component that absorbs heat, lowers the ambient temperature, and reduces the risk of combustion. This application provides flame retardants 41d between each metal grid 41b1 to separate adjacent metal grids 41b1, which helps prevent the metal grids from fusing in the event of a transient electrical overload.

[0146] The orthographic projections of the flame retardant 41d and the metal grid group 41b of the present application on the above-mentioned metal base 41a overlap with the above-mentioned 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 in the event of instantaneous electronic overload.

[0147] Combine Figure 6 It can be seen that the metal bars 41b1 of the present application are arranged flush with the flame retardants 41d, which not only serves to cut off 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 both include a plurality of bars. In these embodiments, the present application further selects the metal bars and flame retardants to have the same size, 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 the electrons will cause the connected metal bars to melt, thereby preventing the short circuit from continuing and disconnecting the circuit, reducing the probability of thermal runaway of the battery.

[0150] The battery short circuits of this application include external wire short circuits and internal short circuits. External wire short circuits refer to when the positive and negative poles of the external wires touch, and the current flows directly from the positive pole to the negative pole without passing through the electrolyte and diaphragm inside the battery, resulting in a runaway electrochemical reaction. Internal short circuits refer to the presence of conductive material (such as metal sheets) or electrolyte leakage between the positive and negative poles of the battery, which will form an internal short circuit in the battery. In addition, it also includes short circuits caused by over-discharge of the battery, or battery short circuits caused by mechanical damage to the battery casing. Battery short circuits 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 direction of the metal bars. In these embodiments, the present application discloses 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°, and 90°, or any value within the range 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 in Figure 7 Only a portion of the metal grid arrangement is shown in the figure. Regardless of the arrangement, the metal grid can be melted when there is a sudden electronic overload.

[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; satisfying: 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 melt 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. Within the numerical range of this 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, and 0.9, or any one of the values ​​within the range of any two of the above values.

[0160] In some embodiments, the angle formed by the third direction and the first direction is 90°, and the 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 Figure 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 oppositely arranged, and the second metal grid 41b1-2 includes a C' surface and a D' surface that are oppositely 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 operating normally, and to facilitate the metal grid to melt when the electrons are instantly overloaded when the battery is short-circuited, in addition to further limiting the thickness h of the metal grid, this application also needs to limit the size of the metal grid in the second direction. When the above 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 ranges of any two of the above values.

[0166] The battery cell of the present application includes an electrode plate, which 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, which includes a positive electrode active material. 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 this application can be measured using instruments and methods known in the art. For example, a thermal conductivity meter can be used, including cutting the current collector into a 5 cm x 5 cm sample and measuring the thermal conductivity of the sample using a TC3000 thermal conductivity meter. Specific testing methods can be referred 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 specific values ​​of the current collector are given in the subsequent specific embodiments of the present application.

[0170] In some embodiments, 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;

[0171] 0≤v<0.2.

[0172] The lithium nickel cobalt manganese oxide 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. This active material combined with the current collector of the present application is beneficial to reducing the probability of the battery experiencing the above-mentioned thermal runaway.

[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 ​​within any two ranges.

[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 ​​within the range of any two of the above values.

[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 ​​within the range of any two of the above values.

[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 ​​within the range of any two of the above.

[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 ​​within the range of any two of the above values.

[0178] In some embodiments, the battery cell includes an isolator; the isolator includes a substrate and a coating located on at least one side of the substrate; the coating includes any one or more of an organic coating and 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 one or more of SiO2, Al2O3, AlOOH, CaO, TiO2, MgO, ZnO, ZrO2, Mg(OH)2 and BaSO4.

[0181] The organic or inorganic coating in this application acts as an insulator, reducing the probability of a short circuit caused by puncturing the separator. In other words, the use of a separator containing a coating in this application first reduces the probability of a short circuit. Even if a short circuit occurs, the current collector designed in this application can quickly shut off the short circuit, improving safety.

[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-containing onium ions, and the anion of the ionic liquid additive includes any one or more of halogen ions, phosphate ions, borate ions, and sulfonimide anions.

[0183] In this application, the electrolyte is the carrier of ion transport 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 composed entirely 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 ([PF6] - ), tetrafluoroborate ([BF4] - ), 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 anion.

[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, and 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 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.

[0188] In some embodiments, the flame retardant component includes 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 halides, 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 diphosphonite, 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 series 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 phosphates of the present application include 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] In addition to the flame retardant mentioned above, the flame retardant component of the present application also includes 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, separator 3 and negative electrode sheet 1 of the present application can be wound or laminated to form a secondary battery. Figure 10 The secondary battery 10 is formed by a winding method, and the Figure 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 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 elaborate on them. Figure 5 Only one winding method is illustrated in the figure, and other lamination or winding methods are within the scope of protection of this application.

[0204] like Figure 11 As shown in FIG. 2 , 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: Figure 11 It is shown that a positive electrode film layer 21 is provided on the surface of either side of the positive electrode current collector 4. The positive electrode film layer 21 can also be located on both sides 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 this 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 Figure 12 As shown in FIG. 1 , 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. Figure 12 The figure only shows that the metal layer is provided on one side of the surface.

[0207] The organic support layer of this application has low thermal conductivity and good thermal insulation properties, which first reduces the probability of short circuits. Even if a short circuit occurs, the current collector designed in this application can quickly cut off the short circuit, thereby improving safety. 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 machine support layer includes any one or more of mechanical rolling, bonding, vapor deposition, chemical plating and electroplating methods.

[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 specimens, measuring the thickness h (μm) of the specimen with a micrometer, and using a Gotech tensile 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 device displacement y (mm) until the specimen 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 comprises any one or more of a polymer material and a polymer composite material. The polymer material comprises one or more of terephthalate, polyethylene, polypropylene, epoxy resin, polyamide, polyimide, polyester, polyolefin, polyacetylene, siloxane polymer, polyether, polyol, polysulfone, polysaccharide polymer, amino acid polymer, polysulfur nitride polymer, aromatic ring polymer, aromatic heterocyclic polymer, epoxy resin, phenolic resin, derivatives thereof, cross-linked products thereof, and copolymers thereof.

[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 supporting 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. 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 a 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 methods including vapor deposition, in-situ formation and coating.

[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 Figure 13 As shown in the figure, a first metal layer 41' and a second metal layer 41" are respectively provided on two opposite surfaces of the organic support layer 42. The negative electrode active material layer 11 is provided on the surface of the first metal layer 41' away from the organic support layer 42, and the positive electrode active material layer 21 is provided on the surface of the second metal layer 41" away from the organic support layer 42.

[0219] This design approach adopted in this application is conducive to further improving 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, which includes 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 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 includes:

[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 this 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 surface of the organic support layer. In these embodiments, the present application discloses that the metal layer is formed on at least one surface of the organic support layer by any one or more methods such as bonding, vapor deposition, electroplating, and chemical plating.

[0233] [Positive electrode]

[0234] According to some embodiments of the present application, as described above, the positive electrode plate includes 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 includes 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 PO4, 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 manganate layered oxide; the lithium nickel cobalt manganate 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-site doping element, and the oxygen-site 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 lithium nickel cobalt manganese oxide 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. This active material combined with the current collector of the present application is beneficial to reducing the probability of the battery experiencing the above-mentioned thermal runaway.

[0238] In some embodiments, the positive electrode active material is not limited to LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM111), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 CO 0.2 Mn 0.2 O2(NCM622),LiNi 0.8 CO 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 CO 0.15 Al 0.05 One or more of O2, LiFePO4 (LFP) and LiMnPO4.

[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. 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 layer and a metal layer formed on at least one surface of the polymer material base layer. 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-side 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 (2.8g / 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 surface or both surfaces 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 manufacturer and model 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, SnO2, etc. And the present application is not limited to these materials, and other traditional 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] In some embodiments, the present application discloses 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 current 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 the negative electrode film layer.

[0247] [Isolator]

[0248] Some embodiments of the present application disclose an isolator. The present application does not impose any particular restriction on the type of isolator, and any known porous isolator with good chemical stability and mechanical stability may be selected.

[0249] In some embodiments, the separator 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; and the coating includes a ceramic coating and / or a polymer coating. The base material layer has good lithium ion permeability, facilitating lithium ion migration; the base material layer is provided with a coating, which can further enhance the mechanical properties of the separator. Furthermore, the ceramic particles in the ceramic coating include one or more of SiO2, Al2O3, AlOOH, CaO, TiO2, MgO, ZnO, ZrO2, Mg(OH)2, and BaSO4. The ceramic coating of the present application acts as an insulator, reducing the probability of a short circuit caused by puncturing the separator. In other words, the present application utilizes a separator including a ceramic coating, which first reduces the probability of a short circuit. Even if a short circuit occurs, the current collector of the above-described design of the present application can quickly shut off the short circuit, thereby improving safety.

[0250] In some embodiments, 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). The polymer coating layer can be made of the same material as or different from the base material layer. The thickness of the polymer coating layer and the base material layer can be different. Furthermore, the thickness of the polymer coating layer is less than the thickness of the base material layer.

[0251] In other embodiments, the separator can be made of at least one of fiberglass, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator 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 can be liquid, solid, or gel. 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 RClO4, RAsF6, RPF6, RBF4, RSbF6, RSO3F, RN(FSO2)2, etc.; fluorine-containing organic metal salts, such as RCF3SO3, RN(FSO2)(CF3SO2), RN(CF3SO2)2, RN(C2F5SO2)2, cyclic 1,3-hexafluoropropane disulfonyl imide lithium, cyclic 1,2-tetrafluoroethane disulfonyl imide lithium, RN(CF3SO2)(C4F9S O2), RC(CF3SO2)3, RPF4(CF3)2, RPF4(C2F5)2, RPF4(CF3SO2)2, RPF4(C2F5SO2)2, RBF2(CF3)2, RBF2(C2F5)2, RBF2(CF3SO2)2, RBF2(C2F5SO2)2, etc.; and metal salts containing dicarboxylic acid complexes, such as lithium bis(oxalato)borate, lithium difluorooxalatoborate, lithium tris(oxalato)phosphate, lithium difluorobis(oxalato)phosphate, lithium tetrafluoro(oxalato)phosphate, etc. The metal and R here both contain lithium ions.

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

[0255] As described above, the organic solvent includes any one or more of carboxylate compounds, carbonate compounds, and ether compounds. Among them, the carboxylate 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), methylpropyl carbonate (MPC), ethylpropyl 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, and dimethyl phthalate. The organic solvents of the present application further include one or both of nitrile solvents and sulfone solvents. Nitrile solvents include one or more of acetonitrile (AN), glutaronitrile (GLN), and adiponitrile (ADN). Sulfone solvents include at least one of sulfolane (SF), dimethyl sulfone (MSM), ethylmethyl sulfone (EMS), and diethyl sulfone (ESE), or a combination of two.

[0256] According to some embodiments of the present application, the electrolyte further includes a film-forming stabilizer, which includes a positive electrode film-forming stabilizer and a negative electrode film-forming stabilizer, wherein the positive electrode film-forming stabilizer includes a carbonate additive and / or a sulfate additive, and the carbonate additive includes one or more of vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), vinyl ethylene carbonate (VEC) and dioctyl carbonate (CC). The sulfate additive includes a cyclic sulfonate additive and / or an alkyl sulfate additive; further, the cyclic sulfonate additive includes one or more of 1,3-propane sultone (PS), propylene sultone (PES), and 3-fluoro-1,3-propane sultone (FPS); the alkyl sulfate additive includes one or more of vinyl sulfate (DTD), diethyl sulfate (DES) and dimethyl sulfate (DMS). The negative electrode film-forming stabilizer includes one or more boron lithium salts, phosphorus-containing lithium salts, and sulfur-containing lithium salts; the boron-containing lithium salts include one or more of lithium tetrafluoroborate (LiBF4), lithium bis(oxalatoborate) (LiBOB), and lithium bis(fluorooxalatoborate) (LiDFOB); the phosphorus-containing lithium salts include one or more of lithium difluorophosphate (LiPO2F2), lithium fluorophosphate (Li2PO3F), and lithium phosphate (Li3PO4). The sulfur-containing lithium salts include one or more of lithium fluorosulfonate (LiFSO3), lithium sulfate (Li2SO4), and lithium sulfamate (LiSO3NH2).

[0257] In some embodiments, the electrolyte further comprises an ionic liquid additive, wherein the cation of the ionic liquid additive comprises any one or more of nitrogen-containing onium ions and phosphonium-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.

[0258] In this application, the electrolyte is the carrier of ion transport 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 composed entirely 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 ([PF6] - ), tetrafluoroborate ([BF4] - ), 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 anion.

[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, and 1-benzyl-3-methylimidazolium bis(fluorosulfonyl)imide, and can be 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 with reference to specific embodiments.

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

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

[0265] The present application can adopt conventional techniques of inorganic chemistry within the art. In the following examples, efforts have been 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 used in the following examples (in degrees Celsius) are expressed in ° C, and the pressures are atmospheric pressure or near atmospheric pressure. All pharmaceutical reagents were purchased as AR grade, and all reactions were carried out under argon protection. Unless otherwise noted, all reagents were obtained from commercial sources.

[0266] Experimental materials:

[0267] The positive electrode active material, negative electrode active material, metal and 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 of 4 GPa, thickness of 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 surface of the organic support layer in the 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 the 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 grooves and metal grids on the metal layer, wherein the depth of the grooves is 1.5 μm (h=1.5 μm, h / H=30%), the width of the metal grids 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 a flame retardant phosphonate (bisphenol A bis(triphenyl phosphate)) and a polyacrylate (polymethyl acrylate) binder in a weight ratio of 9:1 to deionized water, and stirring in a high-speed mixer to obtain a uniformly dispersed slurry, wherein the solid content of the slurry is 50 wt.%;

[0274] S500, coating the above slurry in the grooves formed between adjacent metal bars and completely filling the grooves, and placing in a vacuum dryer at 50°C for 12 hours to prepare 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 difference between the preparation method and the above-mentioned Preparation Example 1 is that the width of the metal grid is adjusted to 100 μm so that y / x=50%, and the other aspects remain 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 difference between the preparation method and the above-mentioned Preparation Example 1 is that the width of the metal grid is adjusted to 180 μm so that y / x=90%, and the other conditions remain 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 differs 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 remains 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 difference between the preparation method and the above-mentioned preparation example 4-1 is that the width of the metal grid is adjusted to 100 μm so that y / x=50%, and the other methods remain the same as the preparation example 4-1.

[0285] Preparation Example 4-3

[0286] A method for preparing a negative electrode current collector (copper) is provided. The difference between the preparation method and the above-mentioned preparation example 4-1 is that the width of the metal grid is adjusted to 180 μm so that y / x=90%, and the other conditions remain the same as those of the preparation example 4-1.

[0287] Preparation Example 5-1

[0288] A method for preparing a negative electrode current collector (copper) is provided. The method differs 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 remains 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 difference between the preparation method and the above-mentioned preparation example 5-1 is that the width of the metal grid is adjusted to 100 μm so that y / x=50%, and the other methods remain the same as the preparation example 5-1.

[0291] Preparation Example 5-3

[0292] A method for preparing a negative electrode current collector (copper) is provided. The difference between the preparation method and the above-mentioned preparation example 5-1 is that the width of the metal grid is adjusted to 180 μm so that y / x=90%, and the other conditions remain the same as those of the preparation example 5-1.

[0293] Preparation Example 6-1

[0294] A method for preparing a current collector is provided. The method differs 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 differs from the above-mentioned Preparation Example 1 in that no metal grids and flame retardants are provided, and the rest of the method remains 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 of the metal grid away from the metal layer is covered with a metal foil of the same thickness and material as the metal layer. The 10*10cm 2 The charge on the current collector. Use a DC regulated voltage and current power supply, with the positive electrode connected to the metal layer of the current collector and the negative electrode connected to the metal foil covered by the metal grid. Apply 1C, 3C, 6C, and 10C of charge, respectively. Observe the metal grid on the current collector for melting within 30 minutes. If melting occurs, immediately cut off the power supply. Record the time and current of the melting. The results are shown in Table 1-1:

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

[0300]

[0301]

[0302] From the above-mentioned current collector overload capacity test, it can be seen that as the thickness and width of the metal grid increase, the current required for the metal grid to melt becomes larger and the time becomes longer, which indicates that the metal grid has a larger fuse current as a "fuse". But in fact, a metal grid with a fuse current that is too large or too small is not suitable for the battery. Because an excessively large fuse current means that even the current during a short circuit may not be able to cause the metal grid to melt, which will not be able to cut off the circuit in time and prevent thermal runaway; but an excessively small 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 increased polarization, resulting in lithium plating in the battery and a sharp drop in battery capacity. 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 5 cm×5 cm sample, 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 sides of the organic support layer in the thickness direction, and the rest remains 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 0.1O2 (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 above-mentioned positive electrode current collector aluminum foil and heated and dried. Specifically, a multi-section oven was used with the temperature settings of 120℃ / 100℃ / 90℃ in sequence. Then, a cold press was used for compaction, and the compacted density of the positive electrode film layer was 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 temperature of the nine-section oven was set at 100℃ / 100℃ / 95℃ / 85℃ / 85℃ / 80℃ / 80℃ / 80℃ / 60℃ for drying. Then, a cold press was used for compaction. 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 <10ppm, EC (ethylene carbonate), PC (polycarbonate), and DMC (dimethyl carbonate) were mixed in a weight ratio of EC:PC:DMC=3:3:3, and then LiPF6, VC, DTD, and PS were added and stirred evenly to obtain an electrolyte, wherein the concentration of LiPF6 in the lithium-ion battery electrolyte was 1mol / L, and the mass percentages of VC, DTD, and PS were 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 remain 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 remain 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 remain 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 remain 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 O2(NCM811) replaced by LiNi 0.9 Co 0.05 Mn 0.05 O2, and 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%. Other aspects remain 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, such as Figure 13 , and the rest remain the same as in Example 1.

[0339] Comparative Example 1

[0340] A method for preparing a battery cell 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, this 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 this 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 battery's discharge specific capacity C0 is recorded at this time; then the battery is charged to 4.4V at currents of 1C, 3C, 6C, and 10C respectively, and then discharged to 2.5V at 0.33C, and this cycle is repeated for 10cls. During the cycle, the maximum temperature of the battery surface is monitored to see if it is greater than 150℃ (the monitoring method includes connecting a temperature sensor to the battery surface), and the discharge specific capacity of the last cycle is recorded as C1. The cycle performance at this time = C1 / C0*100%. The test results are as follows:

[0344] Table 2 Performance of battery cells

[0345]

[0346]

[0347] As can be seen from Table 2, compared with Comparative Example 1, the design provided in the embodiment of the present application is beneficial 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 sides of the same organic support layer is conducive to improving the battery energy density and thereby 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 the electrons will cause the connected metal bars to melt, thereby preventing the short circuit from continuing 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 make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions 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 comprises a metal layer and an organic support layer, wherein the metal layer is located on at least one side surface of the organic support 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; Grooves are formed between adjacent metal bars, and flame retardants are provided in the grooves; The orthographic projection of the flame retardant component and the metal grid assembly on the metal base overlaps with the metal base.

2. The battery cell according to claim 1, wherein: 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 disposed 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 opposite to each other, and a 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, wherein: An angle formed between the third direction and the first direction is 90°, and an angle formed between the third direction and the second direction is 90°.

5. The battery cell according to any one of claims 1 to 2, characterized in that: The metal grid group includes a first metal grid and a second metal grid that are adjacently arranged; Along the second direction, the first metal grid includes a C surface and a D surface that are oppositely arranged; The second metal grid includes a C' surface and a D' surface that are opposite to each other, wherein the C' surface is close to the D surface and the D' surface is 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 2, characterized in that: The thermal conductivity of the current collector is 0.01W / (K·m) to 500W / (K·m).

7. The battery cell according to any one of claims 1 to 2, 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 lithium nickel cobalt manganate 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, wherein 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 2, characterized in that: The battery cell includes a separator; The isolation member includes a substrate and a coating located on at least one surface of the substrate, wherein the coating includes any one or more of an organic coating and an inorganic coating.

9. The battery cell according to any one of claims 1 to 2, 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 sulfonimide anions.

10. The battery cell according to any one of claims 1 to 2, characterized in that: The metal substrate and the metal grid group independently 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 halides, 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 2, 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 provided on a surface of the second metal layer away from the organic support layer.

13. A current collector, characterized in that: It comprises a metal layer and an organic support layer, wherein the metal layer is located on at least one side surface of the organic support 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; Grooves are formed between adjacent metal bars, and flame retardants are provided in the grooves; The orthographic projection of the flame retardant component and the metal grid assembly on the metal base overlaps with the metal base.

14. A method for preparing the current collector according to claim 13, characterized in that: The process includes the following: Providing a metal layer and an organic support layer, wherein the metal layer is located on at least one side surface of the organic support 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 flame retardant slurry; Applying the flame retardant slurry into the grooves formed between adjacent metal bars; The current collector is obtained by drying.

15. The preparation method according to claim 14, characterized in that: The preparation of the flame retardant slurry includes: mixing the flame retardant and the binder in a mass ratio of 9:1, adding the mixture into deionized water, and stirring the mixture to form a slurry with a solid content of 45% to 55%.

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