Positive pole piece, battery and electric device

Abstract

The embodiment of the invention provides a positive pole piece, a battery and an electric device, and relates to the field of batteries. The positive pole piece comprises a positive current collector and a first positive active material layer and a second positive active material layer which are arranged on at least one side surface of the positive current collector, the first positive active material layer comprises a first positive active material, and the second positive active material layer comprises a second positive active material; the Dv50 of the first positive electrode active material is less than the Dv50 of the second positive electrode active material; the first positive electrode active material layer further comprises a conductive additive, and the conductive additive comprises a linear carbon-based conductive material and / or a flexible polymer conductive material. According to the positive pole piece, the battery and the power utilization device provided by the embodiment of the invention, the compaction and energy density can be improved, and the cycle performance can also be improved.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to a positive electrode sheet, a battery and an electrical device. Background Art

[0002] A high density of the positive electrode active material layer often corresponds to a high energy density of the battery, so the energy density of the battery can be increased by increasing the density of the positive electrode active material layer. The positive electrode active material layer composed of different positive electrode active materials can have the advantages of the positive electrode active materials in different layers. This type of positive electrode active material layer usually has a large difference in the particle size of the positive electrode active material particles in different layers. Therefore, during the rolling process of this type of positive electrode active material layer, the positive electrode active material layer with a smaller particle size is easily fractured, and the battery cycle performance deteriorates. Summary of the invention

[0003] In view of the above problems, the present application provides a positive electrode plate, a battery and an electrical device, which can improve the cycle performance of the battery.

[0004] In a first aspect, the present application provides a positive electrode plate, which includes a positive electrode current collector and a first positive electrode active material layer and a second positive electrode active material layer arranged on at least one side surface of the positive electrode current collector, wherein the first positive electrode active material layer contains a first positive electrode active material, the second positive electrode active material layer contains a second positive electrode active material, and the Dv50 of the first positive electrode active material is less than the Dv50 of the second positive electrode active material; the first positive electrode active material layer also contains a conductive additive, and the conductive additive includes a linear carbon-based conductive material and / or a flexible polymer conductive material.

[0005] In the technical solution of the embodiment of the present application, there is a difference in the particle size of the first positive electrode active material in the first positive electrode active material layer and the second positive electrode active material in the second positive electrode active material layer. By adding linear carbon-based conductive materials and / or flexible polymer conductive materials to the first positive electrode active material layer with small particles, lithium ions can be normally transmitted in the electrode sheet when the electrode sheet adopts high pressure density to improve the energy density, thereby improving the cycle performance of the battery. The present application can reduce the phenomenon that the lithium ion transmission path becomes longer or even cannot be transmitted due to the intralayer fracturing of the first positive electrode active material layer with small particles, causing some adjacent first positive electrode active material particles to lose electrical contact; by adding linear carbon-based conductive materials to the first positive electrode active material layer, the first positive electrode active material at the fracturing position can be connected, so that lithium ions can be normally transmitted; by adding flexible polymer conductive materials to the first positive electrode active material layer, it has a filling effect to reduce the fracturing problem, so that lithium ions can be normally transmitted.

[0006] In some embodiments, the mass percentage of the conductive additive in the first positive electrode active material layer is 0.1%-5%, and can be 0.5%-2%. Adding a certain amount of conductive additive can reduce the difficulty of lithium ion transmission caused by intralayer fracturing and reduce the impact on the performance of the positive electrode sheet itself.

[0007] In some embodiments, the first positive electrode active material layer is closer to the positive electrode current collector than the second positive electrode active material layer; and / or, the first positive electrode active material layer and the second positive electrode active material layer are disposed on both sides of the positive electrode current collector. The first positive electrode active material layer of the lower layer (closer to the positive electrode current collector) has small particles and a conductive additive is added, and the positive electrode active material layer is disposed on both sides of the positive electrode current collector, which can improve the cycle performance of the battery.

[0008] In some embodiments, the first positive electrode active material and / or the second positive electrode active material comprises at least one of an olivine structure material, a layered structure material, and a spinel material; optionally, the first positive electrode active material and the second positive electrode active material are different materials. The first positive electrode active material and the second positive electrode active material have a wide range of choices, and different first positive electrode active materials and second positive electrode active materials can enable the positive electrode sheet to have the advantages of different positive electrode active materials.

[0009] In some embodiments, the olivine structural material includes at least one of lithium iron phosphate, lithium vanadium phosphate, lithium manganese iron phosphate, and doping materials and coating materials of the above materials;

[0010] The layered structure material includes at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese aluminum oxide, lithium cobalt oxide, lithium manganese oxide, lithium-rich positive electrode material, and doping materials and coating materials of the above materials;

[0011] The spinel material includes lithium nickel manganese oxide, lithium manganese oxide, and at least one of doping materials and coating materials of the above materials.

[0012] In some embodiments, the first positive electrode active material is an olivine structure material, and the second positive electrode active material is a layered structure material; optionally, the first positive electrode active material includes at least one of lithium iron phosphate (LFP) and lithium iron manganese phosphate (LMFP); the second positive electrode active material includes at least one of lithium nickel cobalt manganese oxide (NCM), lithium cobalt oxide (LCO), and lithium manganese oxide. The first positive electrode active material with an olivine structure and the second positive electrode active material with a layered structure are layered and coated, so that the positive electrode plate can take into account both high safety performance and high energy density. At the same time, by adding linear carbon-based conductive materials and / or flexible polymer conductive materials to the first positive electrode active material with smaller particles, the positive electrode plate can enable normal transmission of lithium ions under high pressure and density.

[0013] In some embodiments, the conductive additive includes the linear carbon-based conductive material and the flexible polymer conductive material, and the mass ratio of the linear carbon-based conductive material to the flexible polymer conductive material is 1:(0.1-10), and can be 1:(0.5-2). At the same time, adding the linear carbon-based conductive material and the flexible polymer conductive material to the first positive electrode active material layer of small particles can not only reduce the phenomenon of fracturing, but also enable the fracturing position to transmit lithium ions normally.

[0014] In some embodiments, the linear carbon-based conductive material has a length of 10-100 μm and a diameter of 10-100 nm; and / or the flexible polymer conductive material has a particle size of 0.05-40 μm.

[0015] In some embodiments, the linear carbon-based conductive material includes one or more of multi-walled carbon nanotubes, single-walled carbon nanotubes, and carbon nanofibers.

[0016] In some embodiments, the flexible polymer conductive material includes a conductive matrix, and the conductive matrix includes one or more of polyethylene terephthalate (PET), polydimethylsiloxane (PDMS), styrene-butadiene-styrene block copolymer (SBS), and polyethylene oxide (PEO); optionally, the mass percentage of the conductive matrix in the flexible polymer conductive material is 5%-100%.

[0017] In some embodiments, the flexible polymer conductive material further comprises a lithium salt, wherein the lithium salt comprises LiPF 6 、LiClO 4 , LiBF 4 , LiBOB, LiTFSI or more; Optionally, the flexible polymer conductive material further includes an additive, wherein the additive is γ-LiAlO 2 , Li 3 N, LAGP, LATP, LLTO, LLZO, Al 2 O 3 、SiO 2 、TiO 2 、BaTiO 3 One or more; Optionally, the mass ratio of the conductive matrix, the lithium salt and the additive in the flexible polymer conductive material is 1:(0.1-10):(0.1-10).

[0018] In some embodiments, the mass percentage of the first positive electrode active material in the first positive electrode active material layer is 90%-99%; and / or the mass percentage of the second positive electrode active material in the second positive electrode active material layer is 90%-99%.

[0019] In some embodiments, the difference between the Dv50 of the first cathode active material and the Dv50 of the second cathode active material is 4-10 μm.

[0020] In a second aspect, the present application provides a battery, comprising the positive electrode plate of the aforementioned embodiment.

[0021] In a third aspect, the present application provides an electrical device, comprising the battery of the aforementioned embodiment.

[0022] 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

[0023] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0024] Figure 1 A schematic diagram of the structure of a vehicle according to some embodiments of the present application;

[0025] Figure 2 A schematic diagram of the exploded structure of a battery according to some embodiments of the present application;

[0026] Figure 3 A schematic diagram of the structure of a battery cell provided in some embodiments of the present application;

[0027] Figure 4 A schematic diagram of the exploded structure of a battery cell according to some embodiments of the present application;

[0028] Figure 5 This is a schematic diagram of the structure of the positive electrode plate of some embodiments of the present application.

[0029] Icons: 1000-vehicle; 100-battery; 10-casing; 11-accommodating space; 12-first part; 13-second part; 20-battery cell; 21-casing; 211-opening; 22-end cover assembly; 221-end cover; 222-electrode terminal; 23-electrode assembly; 231-positive electrode plate; 2311-positive current collector; 2312-positive active material layer; 2312a-first positive active material layer; 2312b-second positive active material layer; 24-current collecting member; 25-insulating protection member; 200-controller; 300-motor. DETAILED DESCRIPTION

[0030] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0032] In the description of the embodiments of the present application, the technical 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. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0033] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0034] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0035] In the description of the embodiments of the present application, the orientations or positional relationships indicated by technical terms such as "thickness", "up", "down", "top", "bottom", "inside", and "outside" 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 referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the embodiments of the present application.

[0036] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "connection" and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0037] At present, from the perspective of market development, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of power batteries, the market demand is also constantly expanding.

[0038] Research has found that the positive electrode active material layer based on the layered coating of different positive electrode active materials can have the advantages of different layers of positive electrode active materials. For example, the positive electrode active material layer includes two layers of positive electrode active material layers stacked in sequence in the thickness direction, the positive electrode active material of one positive electrode active material layer mainly includes high energy density materials, and the positive electrode active material of the other positive electrode active material layer mainly includes high safety materials. The positive electrode active material layer prepared in this way can have the characteristics of high energy density and high safety.

[0039] Positive electrode active materials with different performance advantages will have large differences in particle size due to process conditions or manufacturing costs, and the particle size differences between the layered positive electrode active material layers will also be relatively large. For the positive electrode active material layer as a whole, the positive electrode active material layer with smaller particles is the main factor affecting the compaction density of the electrode sheet. Different layers of positive electrode active materials have large differences in elongation during cold pressing. As the compaction density increases, the positive electrode active material layer with smaller particles will crack first, resulting in an increase in the lithium ion plasma transmission path, or even the inability to transmit.

[0040] Based on the above considerations, in order to improve the problem that the positive electrode active material layer with smaller particles in the layered positive electrode active material layer is prone to fracturing, resulting in difficulty in ion transmission, a positive electrode plate is designed. By adding a conductive additive to the positive electrode active material layer with smaller particles, the fracturing phenomenon is reduced and / or the connection conductivity at the fracturing position is enhanced, thereby allowing lithium ions to be transmitted normally and improving the cycle performance of the battery.

[0041] The battery cells disclosed in the embodiments of the present application can be used in, but are not limited to, electrical devices such as vehicles, ships, or aircraft.

[0042] The embodiment of the present application provides an electric device using a battery as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0043] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0044] Please refer to Figure 1 , Figure 1 The schematic diagram of the structure of the vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 is provided with a battery 100 inside, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000, for example, the battery 100 can be used as an operating power source of the vehicle 1000.

[0045] The vehicle 1000 may further include a controller 200 and a motor 300 , wherein the controller 200 is used to control the battery 100 to supply power to the motor 300 , for example, to meet the power requirements of starting, navigating, and driving the vehicle 1000 .

[0046] In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0047] Figure 2 This is a schematic diagram of the exploded structure of the battery 100 provided in some embodiments of the present application. Figure 2 The battery 100 includes a housing 10 and a battery cell 20 , and the battery cell 20 is accommodated in the housing 10 .

[0048] The box body 10 is used to provide a storage space 11 for the battery cell 20. In some embodiments, the box body 10 may include a first portion 12 and a second portion 13, and the first portion 12 and the second portion 13 cover each other to define the storage space 11 for accommodating the battery cell 20. Of course, the connection between the first portion 12 and the second portion 13 can be sealed by a sealing member (not shown in the figure), and the sealing member can be a sealing ring, a sealant, etc.

[0049] The first part 12 and the second part 13 can be in various shapes, such as a cuboid, a cylinder, etc. The first part 12 can be a hollow structure with one side open to form a receiving cavity for receiving the battery cell 20, and the second part 13 can also be a hollow structure with one side open to form a receiving cavity for receiving the battery cell 20. The opening side of the second part 13 covers the opening side of the first part 12, thereby forming a box body 10 with a receiving space 11. Of course, if Figure 2 As shown, the first part 12 may be a hollow structure with one side open, and the second part 13 may be a plate-like structure. The second part 13 covers the open side of the first part 12 to form a box body 10 with an accommodating space 11.

[0050] In the battery 100, there can be one or more battery cells 20. If there are more than one battery cell 20, the battery cells 20 can be connected in series, in parallel or in a mixed connection. A mixed connection means that the battery cells 20 are connected in series and in parallel. The battery cells 20 can be directly connected in series, in parallel or in a mixed connection, and then the whole formed by the battery cells 20 can be accommodated in the box 10; of course, the battery cells 20 can be connected in series, in parallel or in a mixed connection to form a battery module, and then the battery modules can be connected in series, in parallel or in a mixed connection to form a whole, and then accommodated in the box 10. The battery cell 20 can be cylindrical, flat, rectangular or in other shapes. Figure 2 The example shows that the battery cell 20 is in a square shape.

[0051] In some embodiments, the battery 100 may further include a busbar component (not shown), and the multiple battery cells 20 may be electrically connected via the busbar component to achieve series connection, parallel connection, or mixed connection of the multiple battery cells 20 .

[0052] Figure 3 This is a schematic diagram of the structure of a battery cell 20 provided in some embodiments of the present application. Figure 4 This is an exploded view of a battery cell 20 provided in some embodiments of the present application. Figure 3 and Figure 4 The battery cell 20 may include a housing 21 , an end cap assembly 22 and an electrode assembly 23 . The housing 21 has an opening 211 , the electrode assembly 23 is accommodated in the housing 21 , and the end cap assembly 22 is used to cover the opening 211 .

[0053] The shape of the housing 21 can be determined according to the specific shape of the electrode assembly 23. For example, if the electrode assembly 23 is a rectangular parallelepiped structure, the housing 21 can be a rectangular parallelepiped structure. Figure 3 and Figure 4 The case where the housing 21 and the electrode assembly 23 are square is exemplarily shown.

[0054] The shell 21 may also be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the embodiment of the present application does not impose any special restrictions on this.

[0055] The end cap assembly 22 includes an end cap 221 and an electrode terminal 222. The end cap assembly 22 is used to seal the opening 211 of the housing 21 to form a closed installation space (not shown), and the installation space is used to accommodate the electrode assembly 23. The installation space is also used to accommodate an electrolyte, such as an electrolyte. The end cap assembly 22 is a component for outputting the electrical energy of the electrode assembly 23. The electrode terminal 222 in the end cap assembly 22 is used to be electrically connected to the electrode assembly 23, that is, the electrode terminal 222 is electrically connected to the tab of the electrode assembly 23. For example, the electrode terminal 222 is connected to the tab through the current collecting member 24 to achieve electrical connection between the electrode terminal 222 and the tab.

[0056] It should be noted that the opening 211 of the shell 21 can be one or two. If the opening 211 of the shell 21 is one, the end cap assembly 22 can also be one, and two electrode terminals 222 can be provided in the end cap assembly 22, and the two electrode terminals 222 are respectively used to electrically connect to the positive pole ear and the negative pole ear of the electrode assembly 23. If the opening 211 of the shell 21 is two, for example, the two openings 211 are provided on opposite sides of the shell 21, and the end cap assembly 22 can also be two, and the two end cap assemblies 22 are respectively covered at the two openings 211 of the shell 21. In this case, the electrode terminal 222 in one end cap assembly 22 can be a positive electrode terminal, which is used to electrically connect to the positive pole ear of the electrode assembly 23; the electrode terminal 222 in the other end cap assembly 22 can be a negative electrode terminal, which is used to electrically connect to the negative electrode sheet of the electrode assembly 23.

[0057] In some embodiments, Figure 4 As shown, the battery cell 20 may further include an insulating protective member 25 fixed to the periphery of the electrode assembly 23, and the insulating protective member 25 is used to insulate and isolate the electrode assembly 23 from the housing 21. Exemplarily, the insulating protective member 25 is a tape bonded to the periphery of the electrode assembly 23. In some embodiments, there are multiple electrode assemblies 23, and the insulating protective member 25 is arranged around the periphery of the multiple electrode assemblies 23, and the multiple electrode assemblies 23 are formed into an integral structure to keep the electrode assembly 23 structurally stable.

[0058] Figure 5 For a schematic diagram of the structure of the positive electrode sheet 231 provided in some embodiments of the present application, please refer to Figure 5The positive electrode sheet 231 includes a positive electrode collector 2311 and a positive electrode active material layer 2312 arranged on at least one side surface of the positive electrode collector 2311, the positive electrode active material layer 2312 includes a first positive electrode active material layer 2312a and a second positive electrode active material layer 2312b, wherein the first positive electrode active material layer 2312a contains a first positive electrode active material, the second positive electrode active material layer 2312b contains a second positive electrode active material, and the Dv50 of the first positive electrode active material is less than the Dv50 of the second positive electrode active material; the first positive electrode active material layer 2312a also contains a conductive additive, and the conductive additive includes a linear carbon-based conductive material and / or a flexible polymer conductive material.

[0059] The positive electrode active material layer 2312 of the positive electrode plate 231 includes at least two positive electrode active material monolayers: a first positive electrode active material layer 2312a and a second positive electrode active material layer 2312b. Dv50 refers to the particle size corresponding to 50% of the cumulative volume measured from the small particle size in the volume-based particle size distribution of the positive electrode active material in the positive electrode active material monolayer. It can represent the overall particle size of the positive electrode active material in the positive electrode active material monolayer.

[0060] Linear carbon-based conductive materials may refer to one-dimensional carbon-based conductive materials with a radial dimension of nanometers and an axial dimension of micrometers. Carbon-based materials mainly refer to materials with carbon as the main body.

[0061] The flexible polymer conductive material may refer to a polymer conductive material that can be deformed when squeezed, such as relatively soft polymer particles.

[0062] The positive electrode current collector 2311 may be a metal foil or a composite current collector. For example, the metal foil may be an aluminum foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0063] The first positive electrode active material layer 2312a contains a first positive electrode active material, which includes one or more positive electrode active materials. The second positive electrode active material layer 2312b contains a second positive electrode active material, which includes one or more positive electrode active materials.

[0064] The median particle size of the first positive electrode active material is smaller than that of the second positive electrode active material. Under the same cold pressing conditions, the first positive electrode active material layer 2312a is more easily fractured than the second positive electrode active material layer 2312b. The present application adds linear carbon-based conductive materials and / or flexible polymer conductive materials to the first positive electrode active material layer 2312a to improve ion transport in the first positive electrode active material layer 2312a, thereby improving the cycle performance of the battery.

[0065] According to some embodiments of the present application, the mass percentage of the conductive additive in the first positive electrode active material layer 2312a is 0.1%-5%, and optionally 0.5%-2%. For example, the mass percentage of the conductive additive in the first positive electrode active material layer 2312a can be 0.1%, 0.3%, 0.5%, 1%, 2%, 3%, 4%, 5%, or an intermediate value between any two of the above values.

[0066] According to some embodiments of the present application, the first positive electrode active material layer 2312a is closer to the positive electrode collector 2311 than the second positive electrode active material layer 2312b; and / or, the first positive electrode active material layer 2312a and the second positive electrode active material layer 2312b are provided on both side surfaces of the positive electrode collector 2311.

[0067] According to some embodiments of the present application, the first positive electrode active material and / or the second positive electrode active material include at least one of an olivine structure material, a layered structure material, and a spinel material; the olivine structure material includes lithium iron phosphate (LFP), lithium vanadium phosphate, lithium iron manganese phosphate (LMFP), and at least one of doping materials and coating materials of the above materials; the layered structure material includes lithium nickel cobalt manganese oxide (NCM), lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese aluminum oxide, lithium cobalt oxide (LCO), lithium manganese oxide (LMO), a lithium-rich cathode material (Li-rich cathode), and at least one of doping materials and coating materials of the above materials; the spinel material includes lithium nickel manganese oxide, lithium manganese oxide, and at least one of doping materials and coating materials of the above materials; optionally, the first positive electrode active material and the second positive electrode active material are different materials.

[0068] Among them, each of the positive electrode active materials listed above can be used as a first positive electrode active material with a larger particle size, or as a second positive electrode active material with a smaller particle size. The specific material selection of the first positive electrode active material and the second positive electrode active material can be designed and adjusted according to the performance requirements of the stratification.

[0069] According to some embodiments of the present application, the first positive electrode active material is an olivine structure material, and the second positive electrode active material is a layered structure material; optionally, the first positive electrode active material includes at least one of lithium iron phosphate (LFP), lithium vanadium phosphate, and lithium manganese iron phosphate (LMFP); the second positive electrode active material includes at least one of lithium nickel cobalt manganese oxide (NCM), lithium cobalt oxide (LCO), and lithium manganese oxide (LMO).

[0070] The lattice stability of the positive electrode active material with an olivine structure is high, the material life is good, and it has excellent safety performance, but the specific capacity is low and the voltage platform is low. The energy density is low when used in power batteries, and the competitive advantage is small; the structural stability of the positive electrode active material with a layered structure is poor, but the specific capacity is high and the voltage platform is high. The first positive electrode active material uses an olivine structure material, and the second positive electrode active material uses a layered structure material. While taking into account the safety performance of the olivine structure material, the layered structure material can be used to improve the energy density of the battery.

[0071] According to some embodiments of the present application, the conductive additive includes a linear carbon-based conductive material and a flexible polymer conductive material, and the mass ratio of the linear carbon-based conductive material to the flexible polymer conductive material is 1:(0.1-10), and can be optionally 1:(0.5-2). Exemplarily, the mass ratio of the linear carbon-based conductive material to the flexible polymer conductive material is 1:0.1, 1:0.3, 1:0.5, 1:0.8, 1:1, 1:2, 1:3, 1:5, 1:7, 1:10, or an intermediate value between any two of the above values.

[0072] According to some embodiments of the present application, the length of the linear carbon-based conductive material is 10-100 μm, and the diameter is 10-100 nm; and / or the particle size of the flexible polymer conductive material is 0.05-40 μm. Exemplarily, the length of the linear carbon-based conductive material is 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 100 μm, or any intermediate value between the above two values, and the diameter is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 100 nm, or any intermediate value between the above two values; the particle size of the flexible polymer conductive material is 0.05 μm, 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, or any intermediate value between the above two values.

[0073] According to some embodiments of the present application, the linear carbon-based conductive material includes one or more of multi-walled carbon nanotubes, single-walled carbon nanotubes, and carbon nanofibers.

[0074] According to some embodiments of the present application, the flexible polymer conductive material includes a conductive matrix, and the conductive matrix includes one or more of polyethylene terephthalate (PET), polydimethylsiloxane (PDMS), styrene-butadiene-styrene block copolymer (SBS), and polyethylene oxide (PEO); optionally, the mass percentage of the conductive matrix in the flexible polymer conductive material is 5%-100%, optionally 20%-40%. Exemplarily, the mass percentage of the conductive matrix in the flexible polymer conductive material is 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, or an intermediate value between any two of the above values.

[0075] According to some embodiments of the present application, the flexible polymer conductive material further includes a lithium salt, and the lithium salt includes LiPF 6 、LiClO 4 , LiBF 4 , LiBOB, LiTFSI or more; Optionally, the flexible polymer conductive material further includes an additive, the additive is γ-LiAlO 2 , Li 3 N, LAGP, LATP, LLTO, LLZO, Al 2 O 3 、SiO 2 、TiO 2 、BaTiO 3 One or more; optionally, the mass ratio of the conductive matrix, lithium salt and additive in the flexible polymer conductive material is 1:(0.1-10):(0.1-10), optionally 1:(0.3-1):(1-3).

[0076] According to some embodiments of the present application, the mass percentage of the first positive active material in the first positive active material layer 2312a is 90%-99%; and / or the mass percentage of the second positive active material in the second positive active material layer 2312b is 90%-99%.

[0077] In some embodiments, each positive electrode active material layer further includes a conductive agent and a binder. The mass percentage of the conductive agent in the positive electrode active material layer is 0.4%-5%, and the mass percentage of the binder is 0.5%-7%.

[0078] Optionally, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, and graphene.

[0079] Alternatively, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0080] According to some embodiments of the present application, the difference between Dv50 of the first positive electrode active material and Dv50 of the second positive electrode active material is 4-10 μm. Exemplarily, the difference between Dv50 of the first positive electrode active material and Dv50 of the second positive electrode active material is 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or an intermediate value between any two of the above values.

[0081] In some embodiments, the first cathode active material has a Dv50 of 0.5-1.2 μm, and the second cathode active material has a Dv50 of 2.5-12 μm.

[0082] In some embodiments, the positive electrode sheet 231 can be prepared in the following manner: the aforementioned positive electrode active material, conductive agent, binder, and optionally other components (conductive additives) are dispersed in a solvent to form a first slurry and a second slurry, respectively; the first slurry and the second slurry are simultaneously or distributedly coated on the positive electrode collector 2311, and after drying, cold pressing and other processes, the positive electrode sheet 231 can be obtained.

[0083] In some embodiments, the thickness of the first positive electrode active material layer 2312a is 30-100 μm, and the thickness of the second positive electrode active material layer 2312b is 30-100 μm. The compaction density of the first positive electrode active material layer 2312a and / or the second positive electrode active material layer 2312b is 2.5-3.5 g / 1540.25 mm 2 , optional: 3-3.5g / 1540.25mm 2 .

[0084] According to some embodiments of the present application, the present application provides a battery, including the positive electrode sheet 231 of the above embodiment. As an implementation mode, the battery includes a battery cell consisting of a negative electrode sheet, a separator and the positive electrode sheet 231 provided above. The battery includes any form of a single cell, a battery module, and a battery pack.

[0085] [Negative electrode]

[0086] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.

[0087] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0088] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, a copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0089] In some embodiments, the negative electrode active material may adopt the negative electrode active material for the battery known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0090] In some embodiments, the negative electrode film layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

[0091] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0092] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0093] In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0094] [Isolation film]

[0095] The present application has no particular limitation on the type of isolation membrane, and any known porous isolation membrane with good chemical stability and mechanical stability can be selected.

[0096] In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0097] In some embodiments, the positive electrode sheet 231 , the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0098] In some embodiments, the secondary battery may include an outer package, which may be used to encapsulate the electrode assembly and the electrolyte.

[0099] In some embodiments, the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the secondary battery may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0100] [Electrolytes]

[0101] The battery cell also includes an electrolyte, which plays a role in conducting ions between the positive electrode plate 231 and the negative electrode plate. The electrolyte can be in a liquid or gel state.

[0102] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0103] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0104] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0105] In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0106] According to some embodiments of the present application, the present application provides an electrical device, comprising the battery of the aforementioned embodiment.

[0107] Next, one or more embodiments are described in more detail with reference to the following examples. Of course, these examples do not limit the scope of one or more embodiments.

[0108] Example 1

[0109] (1) Preparation of positive electrode sheet

[0110] Preparation of the first coating slurry: The first positive electrode active material, the conductive agent carbon black, the binder PVDF and the conductive additive are mixed in a mass ratio of 97%: 0.5%: 1.6%: 0.9%, and N-methylpyrrolidone (NMP) is added, and the first coating slurry is prepared by stirring. In this embodiment, the first positive electrode active material is LiFePO 4 , Dv50 is 0.75μm, the conductive additive is flexible a+linear a, the mass ratio of the two is 1:0.8, and the flexible a is PEO, LiTFSI and γ-LiAlO 2 According to the mixture formed in a mass ratio of 1:0.5:2, the linear carbon-based conductive material is a single-walled carbon nanotube with an average length of 50 μm and an average diameter of 50 nm.

[0111] Preparation of the second coating slurry: The second positive electrode active material, the conductive agent carbon black and the binder PVDF are mixed in a mass ratio of 97%:0.5%:2.5%, and N-methylpyrrolidone (NMP) is added, and the second coating slurry is prepared by stirring. Among them, the second positive electrode active material is LiNi 0.333 Co 0.333 Mn 0.333 O 2 (NCM111), Dv50 is 3.4μm.

[0112] Coating and preparing positive electrode sheet: Use an extrusion coater to simultaneously coat the first coating slurry and the second coating slurry prepared above onto the surface of the aluminum foil, with the first coating slurry on the side close to the aluminum foil and the second coating slurry away from the aluminum foil; the thickness of the first positive electrode active material layer formed on one side is 50 μm, and the compression is 3.2 g / 1540.25 mm 2 The thickness of the second positive electrode active material layer is 50 μm and the compaction is 3.2 g / 1540.25 mm 2 .

[0113] (2) Preparation of negative electrode sheet: negative electrode active material graphite, conductive agent acetylene black, binder styrene butadiene rubber, and thickener sodium carboxymethyl cellulose are mixed in a weight ratio of graphite: acetylene black: styrene butadiene rubber: sodium carboxymethyl cellulose = 95:2:2:1, and an appropriate amount of deionized water is added and stirred to form a uniform negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector copper foil, and then dried and cold pressed to a density of 1.65g / 1540.25mm 2 The single-side thickness is 91 μm, and a negative electrode sheet is obtained.

[0114] (3) Preparation of electrolyte: In an argon atmosphere glove box with a water content of <10 ppm, ethylene carbonate, dimethyl carbonate and 1,2-propylene carbonate were mixed in a volume ratio of 1:1:1, and then LiPF 6 Evenly dissolved in the above solution, LiPF 6 The concentration is 1 mol / L to obtain an electrolyte.

[0115] (4) Preparation of lithium ion secondary batteries (hereinafter referred to as batteries):

[0116] The positive electrode sheet, the isolation film, and the negative electrode sheet are stacked in order, so that the isolation film is placed between the positive and negative electrode sheets to play an isolating role, and then they are wound to obtain a bare battery cell; the bare battery cell is placed in an outer packaging aluminum shell, and the above-prepared electrolyte is injected into the dried battery, and then the battery is obtained after vacuum packaging, standing, forming, shaping and other processes.

[0117] Example 2-16

[0118] According to the raw material requirements in Table 1 and Table 2-3, a battery was prepared using the same preparation method as in Example 1.

[0119] Comparative Examples 1-3

[0120] According to the raw material requirements in Table 1, a battery was prepared using a preparation method similar to that of Example 1, wherein the thickness of the first positive electrode active material layer of Comparative Example 1 was the total thickness of the first positive electrode active material layer and the second positive electrode active material layer in Example 1.

[0121] Table 1 Raw materials of Examples and Comparative Examples

[0122]

[0123]

[0124] Table 2 Composition of different flexible polymer conductive materials

[0125] Material Proportion Flexible <![CDATA[PEO+LiTFSI+γ-LiAlO 2 ]]> 1:0.5:2 Flexible <![CDATA[PEO+LiTFSI+γ-LiAlO 2 ]]> 1:0.1:0.1 Flexible c <![CDATA[PEO+LiTFSI+γ-LiAlO 2 ]]> 1:10:10

[0126] Table 3 Specifications of different linear carbon-based conductive materials

[0127] Material length diameter Linear Single-walled carbon nanotubes 50μm 50nm Linear b Single-walled carbon nanotubes 100μm 10nm Linear c Single-walled carbon nanotubes 10μm 100nm

[0128] Test Method

[0129] (1) Battery 25 / 45℃ cycle performance test

[0130] The batteries prepared in the examples and comparative examples were subjected to the following tests:

[0131] At 25 / 45℃, the lithium-ion secondary battery is first charged to 4.35V at a constant current of 1C, and then further charged to a current of 0.05C at a constant voltage of 4.35V, and then discharged to 2V at a constant current of 1C. This is a charge and discharge cycle process, and the discharge capacity this time is the discharge capacity of the first cycle. The battery is subjected to multiple cycle charge and discharge tests in the above manner, and the discharge capacity of the 200th cycle is detected, and the capacity retention rate of the battery after the cycle is calculated. The test results are shown in Table 4 below.

[0132] Table 4 Cyclic performance of embodiments and comparative examples

[0133] Battery ID 25℃ Cycle capacity retention rate / % 45℃ cycle capacity retention rate / % Example 1 91.11 88.33 Example 2 88.59 85.89 Example 3 91.56 88.77 Example 4 90.02 87.27 Example 5 90.07 87.32 Example 6 90.19 87.44 Example 7 90.21 87.46 Example 8 90.11 87.36 Example 9 91.04 88.26 Example 10 91.05 88.27 Embodiment 11 91.02 88.24 Example 12 91.03 88.25 Example 13 88.87 86.16 Embodiment 14 89.33 86.60 Embodiment 15 92.45 89.63 Example 16 91.86 89.06 Comparative Example 1 82.67 78.82 Comparative Example 2 86.35 84.65 Comparative Example 3 86.41 84.31

[0134] Compared with Comparative Examples 1-3, in Examples 1-16, conductive additives were added to the positive electrode active material layer with a relatively smaller Dv50 of the positive electrode active material, and the battery cycle performance was improved.

[0135] Among them, according to Examples 1-3, it can be seen that when the mass percentage of the conductive additive added to the positive electrode active material layer is 0.5%-2%, the cycle performance of the battery can be improved to varying degrees.

[0136] It can be seen from Example 1 and Examples 4-5 that when the added conductive additives include linear carbon-based conductive materials and / or flexible polymer conductive materials, the cycle performance of the battery can be improved.

[0137] According to Example 1 and Examples 6-8, when the mass ratio of the linear carbon-based conductive material and the flexible polymer conductive material in the added conductive additive is 1:(0.1-10), which can be optionally 1:(0.8-2), the cycle performance of the battery is greatly improved.

[0138] According to Example 1 and Examples 9-12, when different materials are used for the linear carbon-based conductive material and the flexible polymer conductive material in the added conductive additive, the cycle performance of the battery can be improved to different degrees.

[0139] According to Example 1, Examples 13-14 and Examples 15-16, when the positive electrode active material layer uses different positive electrode active materials, adding a conductive additive to the positive electrode active material layer with a relatively smaller Dv50 of the positive electrode active material can improve the battery cycle performance; when the difference in Dv50 of the positive electrode active materials of the layered positive electrode active material layers is 7-10μm, adding a conductive additive to the positive electrode active material layer with a relatively smaller Dv50 of the positive electrode active material can greatly improve the battery cycle performance.

[0140] (2) Film resistance of the positive electrode

[0141] The cold pressed electrode is cut into 1540.25mm by a cutting machine. 2 The small disc is then put into a diaphragm resistance tester to test the diaphragm resistance. The test is 10ea and the average value is taken to obtain the results shown in Table 5.

[0142] Table 5 Diaphragm resistance of the embodiments and comparative examples

[0143] Battery ID Diaphragm resistance / Ω Comparative Example 1 0.6411 Comparative Example 2 0.7523 Comparative Example 3 0.5921 Example 1 0.4335

[0144] Compared with Comparative Examples 1-3, the diaphragm resistance of Example 1 is lower, indicating that the conductivity of the diaphragm is better; among them, although the total amount of the conductive agent added in Comparative Example 3 is equal to the total amount of the conductive agent + conductive additive added in Example 1, the diaphragm resistance of Comparative Example 3 is still higher than the diaphragm resistance of Example 1. This is because after cold pressing, part of the conductive network formed by the conductive agent will be squeezed and destroyed, while the conductive additive composed of the linear carbon-based conductive material and the flexible polymer conductive material added in the present application will also maintain a strong conductive network after cold pressing.

[0145] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

Claims

1. A positive electrode sheet, It is characterized in that It includes a positive electrode current collector and a first positive electrode active material layer and a second positive electrode active material layer arranged on at least one side surface of the positive electrode current collector, wherein the first positive electrode active material layer contains a first positive electrode active material, the second positive electrode active material layer contains a second positive electrode active material, and the Dv50 of the first positive electrode active material is less than the Dv50 of the second positive electrode active material; the first positive electrode active material layer also contains a conductive additive, and the conductive additive includes a linear carbon-based conductive material and / or a flexible polymer conductive material.

2. The positive electrode sheet according to claim 1, It is characterized in that The mass percentage of the conductive additive in the first positive electrode active material layer is 0.1%-5%, and can be 0.5%-2%.

3. The positive electrode sheet according to claim 1 or 2, It is characterized in that The first positive electrode active material layer is closer to the positive electrode collector than the second positive electrode active material layer; and / or the first positive electrode active material layer and the second positive electrode active material layer are disposed on both sides of the positive electrode collector.

4. The positive electrode sheet according to any one of claims 1 to 3, It is characterized in that The first positive electrode active material and / or the second positive electrode active material include at least one of an olivine structure material, a layered structure material, and a spinel material; optionally, the first positive electrode active material and the second positive electrode active material are different materials.

5. The positive electrode sheet according to claim 4, It is characterized in that The olivine structural material includes lithium iron phosphate, lithium vanadium phosphate, lithium manganese iron phosphate, and at least one of doping materials and coating materials of the above materials; The layered structure material includes at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese aluminum oxide, lithium cobalt oxide, lithium manganese oxide, lithium-rich positive electrode material, and doping materials and coating materials of the above materials; The spinel material includes lithium nickel manganese oxide, lithium manganese oxide, and at least one of doping materials and coating materials of the above materials.

6. The positive electrode sheet according to claim 4 or 5, It is characterized in that The first positive electrode active material is an olivine structure material, and the second positive electrode active material is a layered structure material; optionally, the first positive electrode active material includes at least one of lithium iron phosphate, lithium vanadium phosphate, and lithium iron manganese phosphate; the second positive electrode active material includes at least one of lithium nickel cobalt manganese oxide, lithium cobalt oxide, and lithium manganese oxide.

7. The positive electrode sheet according to any one of claims 1 to 6, It is characterized in that The conductive additive includes the linear carbon-based conductive material and the flexible polymer conductive material, and the mass ratio of the linear carbon-based conductive material to the flexible polymer conductive material is 1:(0.1-10), and can be optionally 1:(0.5-2).

8. The positive electrode sheet according to any one of claims 1 to 7, It is characterized in that The linear carbon-based conductive material has a length of 10-100 μm and a diameter of 10-100 nm; and / or the flexible polymer conductive material has a particle size of 0.05-40 μm.

9. The positive electrode sheet according to any one of claims 1 to 8, It is characterized in that The linear carbon-based conductive material includes one or more of multi-walled carbon nanotubes, single-walled carbon nanotubes, and carbon nanofibers.

10. The positive electrode sheet according to any one of claims 1 to 8, It is characterized in that The flexible polymer conductive material includes a conductive matrix, and the conductive matrix includes one or more of polyethylene terephthalate, polydimethylsiloxane, styrene-butadiene-styrene block copolymer, and polyethylene oxide; optionally, the mass percentage of the conductive matrix in the flexible polymer conductive material is 5%-100%.

11. The positive electrode sheet according to claim 10, It is characterized in that The flexible polymer conductive material also includes a lithium salt, and the lithium salt includes LiPF 6 、LiClO 4 , LiBF 4 , LiBOB, LiTFSI or more; Optionally, the flexible polymer conductive material further includes an additive, wherein the additive is γ-LiAlO 2 , Li 3 N, LAGP, LATP, LLTO, LLZO, Al 2 O 3 、SiO 2 、TiO 2 、BaTiO 3 One or more; Optionally, the mass ratio of the conductive matrix, the lithium salt and the additive in the flexible polymer conductive material is 1:(0.1-10):(0.1-10).

12. The positive electrode sheet according to any one of claims 1 to 11, It is characterized in that The mass percentage of the first positive electrode active material in the first positive electrode active material layer is 90%-99%; and / or the mass percentage of the second positive electrode active material in the second positive electrode active material layer is 90%-99%.

13. The positive electrode sheet according to any one of claims 1 to 12, It is characterized in that The difference between Dv50 of the first positive electrode active material and Dv50 of the second positive electrode active material is 4-10 μm.

14. A battery, It is characterized in that Comprising the positive electrode sheet as described in any one of claims 1-13.

15. An electrical device, It is characterized in that Comprising the battery of claim 14.

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