Positive pole piece, battery and electric device

Abstract

The invention provides a positive pole piece, a battery and an electric device. The positive electrode plate comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the positive electrode film layer comprises a first region and a second region, and the first region is located between the positive electrode current collector and the second region in the thickness direction of the positive electrode film layer; the first region comprises a positive active material and a flame retardant; the flame retardant is added into the first region, so that the thermal runaway process can be effectively slowed down, the safety performance of the battery is improved, and meanwhile, the low-temperature performance and the rate capability of the battery are ensured.

Description

Technical Field

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

[0002] In recent years, with the rapid development of secondary batteries, they have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields. However, during the use of secondary batteries, extreme external high temperatures or rapid internal temperature rise may lead to heat accumulation and thermal runaway, further causing fires or even explosions, which seriously threaten the safety performance of the batteries. Summary of the invention

[0003] The present application is made in view of the above-mentioned problems, and its purpose is to provide a positive electrode plate that can effectively slow down the process of thermal runaway, improve the battery safety performance while ensuring the low temperature performance and rate performance of the battery.

[0004] In order to achieve the above-mentioned objectives, the present application provides a positive electrode plate, a battery and an electrical device.

[0005] The first aspect of the present application provides a positive electrode plate, including a positive electrode collector and a positive electrode film layer arranged on at least one side of the positive electrode collector, the positive electrode film layer includes a first region and a second region, and along the thickness direction of the positive electrode film layer, the first region is located between the positive electrode collector and the second region; the first region includes a positive electrode active material and a flame retardant.

[0006] Therefore, the present application adds a flame retardant in the first region. When the temperature in the battery rises rapidly, the flame retardant can undergo a strong endothermic reaction, absorb part of the heat in a short time, and effectively inhibit the generation of combustible gases, thereby effectively slowing down the progress of thermal runaway and delaying the occurrence of severe thermal runaway, thereby improving the safety performance of the battery; at the same time, along the thickness direction of the positive electrode film layer, the first region is arranged between the positive electrode current collector and the second region, which can prevent the flame retardant from complexing with the solvent in the electrolyte on the surface of the positive electrode film layer, increasing the interfacial impedance, thereby deteriorating the low temperature performance and rate performance of the battery; the positive electrode plate of the present application can effectively slow down the progress of thermal runaway, improve the safety performance of the battery, and ensure the low temperature performance and rate performance of the battery.

[0007] In any embodiment, the flame retardant includes at least one of a phosphazene compound, a phosphate ester compound or an organic halide.

[0008] Phosphazene compounds are flame retardants with alternating double bonds of P and N as the main chain structure. Due to the good synergistic effect between P and N, they have a high decomposition temperature and flame retardant effect. At the same time, their ionic conductivity is high, which is conducive to the transmission of metal ions (such as lithium ions). Phosphate compounds are an organic phosphorus flame retardant that can decompose at high temperatures to produce PO· free radicals, which can capture hydrogen radicals (H·) and hydroxyl radicals (HO·) generated during the combustion process to form HPO, thereby preventing or slowing down the combustion chain reaction and enhancing the flame retardant effect. Organic halides are a halogen flame retardant that can decompose at high temperatures to produce hydrogen halides, which can eliminate the active free radicals generated by the combustion reaction, thereby slowing down or terminating the combustion chain reaction and achieving the purpose of flame retardancy. Adding the above flame retardant to the first region can slow down the process of thermal runaway and delay the occurrence of severe thermal runaway, thereby improving the safety performance of the battery.

[0009] In any embodiment, the phosphazene compound includes a cyclotriphosphazene compound, and the cyclotriphosphazene compound includes the structural formula shown in formula (I):

[0010]

[0011] Wherein, R1, R2, R3, R4, R5 and R6 are each independently selected from one of fluorine, chlorine, bromine, alkyl, haloalkyl, alkoxy, haloalkoxy, alkenyl, haloalkenyl, alkenyloxy, haloalkenyloxy, aryl, halogenated aryl, aryloxy, halogenated aryloxy, substituted phosphate, substituted sulfonic acid, substituted imide or substituted sulfonimide.

[0012] Cyclotriphosphazene compounds are a class of six-membered heterocyclic and conjugated phosphazene compounds with stable structures. The six-membered heterocyclic ring is composed of three N atoms and three P atoms connected by PN single and double bonds. Compared with linear phosphazene compounds, they have higher thermal stability. They are thermally decomposed at high temperatures to produce polyphosphoric acid and partial polyphosphoric acid, which cover the surface of the carbon layer and play a condensed phase flame retardant role. In addition, phosphorus oxygen free radicals and flame retardant gases (such as PO· and NH3) are also produced during the combustion process, which can terminate the free radical chain reaction and dilute the concentration of combustible gases, further slowing down the combustion and playing a gas phase flame retardant role. Furthermore, adding cyclotriphosphazene compounds to the first region can better slow down the process of thermal runaway and delay the occurrence of severe thermal runaway.

[0013] In any embodiment, the cyclotriphosphazene compound includes at least one of hexafluorocyclotriphosphazene, hexachlorocyclotriphosphazene, methoxy (pentafluoro) cyclotriphosphazene, ethoxy (pentafluoro) cyclotriphosphazene, phenoxy (pentafluoro) cyclotriphosphazene, trifluoroethoxy (pentafluoro) cyclotriphosphazene, methylsulfonate (pentafluoro) cyclotriphosphazene or ethylsulfonate (pentafluoro) cyclotriphosphazene.

[0014] The phosphorus atom in the cyclotriphosphazene is connected to different substituents, especially halogen atoms, through substitution reactions to form a combination of a phosphazene flame retardant and an organic halogenated flame retardant, thereby achieving the purpose of synergistic flame retardancy; further, the addition of the above-mentioned cyclotriphosphazene compound to the first region can better slow down the process of thermal runaway and delay the occurrence of severe thermal runaway.

[0015] In any embodiment, the phosphate compound includes at least one of tris(chloroethyl)phosphate, tris(chloropropyl)phosphate, tris(dibromopropyl)phosphate, triphenyl phosphate, tricresyl phosphate or tri-tert-butylphenyl phosphate.

[0016] By introducing halogen atoms into phosphate compounds, a combination of phosphate flame retardants and organic halogenated flame retardants can be formed to achieve the purpose of synergistic flame retardancy; by introducing benzene ring structures into phosphate compounds, the thermal stability of the flame retardant can be improved and the flame retardant effect can be improved; further, adding the above-mentioned phosphate compounds into the first region can better slow down the process of thermal runaway and delay the occurrence of severe thermal runaway.

[0017] In any embodiment, the organic halogenated compound includes at least one of decabromodiphenyl ether, tetrabromobisphenol A, tetrabromophthalic anhydride, pentabromotoluene or hexabromocyclododecane.

[0018] The above-mentioned organic halides have the advantages of small addition amount, strong flame retardancy and high thermal stability; further, adding the above-mentioned organic halides to the first region can better slow down the progress of thermal runaway and delay the occurrence of severe thermal runaway.

[0019] In any embodiment, based on the total mass of the first region, the mass percentage of the flame retardant is ≤10%, and can be optionally 3%-5%. Within this range, it is beneficial to further effectively slow down the process of thermal runaway, improve the safety performance of the battery, and ensure the low temperature performance and rate performance of the battery.

[0020] In any embodiment, based on the total mass of the first region, the mass percentage of the positive electrode active material is 86%-95%, and can be 91%-93%. Within this range, it is beneficial to further effectively slow down the process of thermal runaway, improve the battery safety performance, and ensure the low temperature performance and rate performance of the battery.

[0021] In any embodiment, the thickness of the first region is 5-50 μm, and can be 20-30 μm. Within this range, it is beneficial to further effectively slow down the process of thermal runaway, improve the safety performance of the battery, and ensure the low temperature performance and rate performance of the battery.

[0022] In any embodiment, the thickness of the second region is 50-100 μm, and can be 65-85 μm. Within this range, it is beneficial to further effectively slow down the process of thermal runaway, improve the battery safety performance, and ensure the low temperature performance and rate performance of the battery.

[0023] The second aspect of the present application also provides a battery, comprising the positive electrode plate of the first aspect of the present application.

[0024] The third aspect of the present application also provides an electrical device, comprising the battery of the second aspect of the present application.

[0025] Therefore, the present application provides a positive electrode plate, which includes a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, and the positive electrode film layer includes a first region and a second region. By adding a flame retardant in the first region, the process of thermal runaway can be effectively slowed down, and the occurrence of severe thermal runaway can be delayed, thereby improving the safety performance of the battery; at the same time, along the thickness direction of the positive electrode film layer, the first region is arranged between the positive electrode current collector and the second region, which can prevent the flame retardant from complexing with the solvent in the electrolyte on the surface of the positive electrode film layer, increasing the interface impedance, thereby deteriorating the low temperature performance and rate performance of the battery. Therefore, the present application includes a battery having the above-mentioned positive electrode plate with significantly improved safety performance. In addition, the present application also includes an electrical device for the battery, and the electrical device also has significantly improved safety performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the positive electrode plate of one embodiment of the present application.

[0027] Figure 2 It is a schematic structural diagram of a positive electrode plate of another embodiment of the present application.

[0028] Figure 3 is a schematic diagram of a secondary battery according to one embodiment of the present application.

[0029] Figure 4 yes Figure 3 An exploded view of a secondary battery according to an embodiment of the present application is shown.

[0030] Figure 5 is a schematic diagram of a battery module according to an embodiment of the present application.

[0031] Figure 6 It is a schematic diagram of a battery pack according to one embodiment of the present application.

[0032] Figure 7 yes Figure 6 An exploded view of a battery pack according to an embodiment of the present application is shown.

[0033] Figure 8FIG. 1 is a schematic diagram of an electric device using a secondary battery according to an embodiment of the present application as a power source.

[0034] Description of reference numerals:

[0035] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 secondary battery; 51 shell; 52 electrode assembly; 53 top cover assembly; 54 positive electrode plate; 541 positive electrode current collector; 542 positive electrode film layer; 5421 first region; 5422 second region. DETAILED DESCRIPTION

[0036] Below, the embodiments of the positive electrode plate, battery and electric device of the present application are specifically disclosed in detail with appropriate reference to the drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0037] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0038] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0039] 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.

[0040] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0041] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0042] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0043] During the use of secondary batteries, factors such as extreme external high temperatures or internal short circuits cause the temperature inside the battery to rise rapidly, thereby dissolving the SEI film and accumulating heat. As a result, the lithium-embedded components in the negative electrode are directly exposed to the electrolyte and react with the electrolyte to decompose, causing the temperature to rise further. When the temperature reaches the decomposition temperature of the positive electrode active material, the positive electrode active material will decompose, release heat and oxygen, which can easily cause thermal runaway, resulting in fire or even explosion, seriously threatening the safety of battery use.

[0044] In the prior art, the safety performance of the battery is improved by adding flame retardant additives to the electrolyte. However, the addition of flame retardant additives can cause complexation on the surface of the positive electrode, increase the interface impedance, and deteriorate the low temperature performance and rate performance of the battery.

[0045] Based on this, the present application proposes a positive electrode plate and a battery and an electrical device including the positive electrode plate. The positive electrode plate of the present application includes a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector. The positive electrode film layer includes a first region and a second region. By adding a flame retardant to the first region, the process of thermal runaway can be effectively slowed down, and the occurrence of severe thermal runaway can be delayed, thereby improving the safety performance of the battery. The safety performance of the battery and the electrical device in the present application is significantly improved.

[0046] [Positive electrode]

[0047] Although the mechanism is not yet clear, the applicant unexpectedly discovered that: by adding a flame retardant to the first region, when the temperature in the battery rises rapidly, the flame retardant can undergo a strong endothermic reaction, absorb part of the heat in a short time, and effectively inhibit the generation of combustible gases, thereby effectively slowing down the progress of thermal runaway and delaying the occurrence of severe thermal runaway, thereby improving the safety performance of the battery; if the flame retardant is directly added to the positive electrode film layer, or the flame retardant is directly added to the second region, the flame retardant is very easy to complex with the solvent in the electrolyte on the surface of the positive electrode film layer, so that the impedance of the surface of the positive electrode film layer increases, thereby deteriorating the low temperature performance and rate performance of the battery; by setting the first region between the positive electrode current collector and the second region along the thickness direction of the positive electrode film layer, and adding a flame retardant in the first region, the present application can effectively slow down the progress of thermal runaway, improve the safety performance of the battery while ensuring the low temperature performance and rate performance of the battery.

[0048] As an example, Figure 1 Schematic diagram of the structure of the positive electrode sheet of one embodiment of the present application. The positive electrode sheet 54 includes a positive electrode current collector 541 and a positive electrode film layer 542 disposed on one side of the positive electrode current collector 541. The positive electrode film layer 542 includes a first region 5421 and a second region 5422. Along the thickness direction of the positive electrode film layer 542, the first region 5421 is located between the positive electrode current collector 541 and the second region 5422. As an example, see Figure 1 , the first region 5421 and the second region 5422 distributed along the thickness direction of the positive electrode film layer 542, the first region 5421 and the second region 5422 are sequentially arranged along the thickness direction of the positive electrode film layer 542, and the boundary between the two overlaps, the first region 5421 is arranged on the surface of the positive electrode current collector 541, and the second region 5422 is arranged on the surface of the first region 5421. The two relative surfaces of the first region 5421 and the second region 5422 distributed along the thickness direction of the positive electrode film layer 542 are perpendicular to the thickness direction of the positive electrode film layer 542. As another example (see Figure 2 ), a first region 5421 and a second region 5422 are distributed along the thickness direction of the positive electrode film layer 542, the first region 5421 and the second region 5422 are spaced apart along the thickness direction of the positive electrode film layer 542, the first region 5421 is arranged at a side close to the positive electrode current collector 541, and the second region is arranged at a side of the positive electrode film layer 542 away from the positive electrode current collector 541. Both relative surfaces of the first region 5421 and the second region 5422 distributed along the thickness direction of the positive electrode film layer 542 are perpendicular to the thickness direction of the positive electrode film layer 542.

[0049] As an example, in a cross section perpendicular to the thickness direction of the positive electrode film layer 542, the first region 5421 and the second region 5422 refer to local regions in the positive electrode film layer 542 that meet the requirements of the specified position; as an example, in a cross section perpendicular to the thickness direction of the positive electrode film layer 542, the first region 5421 and the second region 5422 refer to all regions in the positive electrode film layer 542 that meet the requirements of the specified position. In this application, there is no particular limitation on the cross-sectional size of the first region 5421 and the second region 5422 in the thickness direction perpendicular to the positive electrode film layer 542, as long as the first region 5421 is located between the positive electrode current collector 541 and the second region 5422 along the thickness direction of the positive electrode film layer 542.

[0050] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0051] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer 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.).

[0052] In some embodiments, both the first region and the second region include positive electrode active materials. When the battery is a lithium ion battery, the positive electrode active material may be a positive electrode active material for lithium ion batteries known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates containing olivine structure, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3O2 (also referred to as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds, etc. Examples of lithium-containing phosphates with olivine structure may include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. The positive active materials in the first region and the second region may be the same or different.

[0053] In some embodiments, the first region and the second region may further include a binder. As an example, 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. The binders in the first region and the second region may be the same or different.

[0054] In some embodiments, the first region and the second region may further optionally include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The conductive agents in the first region and the second region may be the same or different.

[0055] In some embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder, the flame retardant and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a first positive electrode slurry, the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a second positive electrode slurry, the first positive electrode slurry is coated on the positive electrode collector to form a first region, the second positive electrode slurry is coated on the first region to form a second region, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0056] In some embodiments, the flame retardant includes at least one of a phosphazene compound, a phosphate ester compound, or an organic halide.

[0057] Phosphazene compounds are flame retardants with alternating double bonds of P and N as the main chain structure. Due to the good synergistic effect between P and N, they have a high decomposition temperature and flame retardant effect. At the same time, their ionic conductivity is high, which is conducive to the transmission of metal ions (such as lithium ions). Phosphate compounds are an organic phosphorus flame retardant that can decompose at high temperatures to produce PO· free radicals, which can capture hydrogen radicals (H·) and hydroxyl radicals (HO·) generated during the combustion process to form HPO, thereby preventing or slowing down the combustion chain reaction and enhancing the flame retardant effect. Organic halides are a halogen flame retardant that can decompose at high temperatures to produce hydrogen halides, which can eliminate the active free radicals generated by the combustion reaction, thereby slowing down or terminating the combustion chain reaction and achieving the purpose of flame retardancy. Adding the above flame retardant to the first region can slow down the process of thermal runaway and delay the occurrence of severe thermal runaway, thereby improving the safety performance of the battery.

[0058] In some embodiments, the phosphazene compound includes a cyclotriphosphazene compound, and the cyclotriphosphazene compound includes a structural formula shown in formula (I):

[0059]

[0060] Wherein, R1, R2, R3, R4, R5, and R6 are each independently selected from one of fluorine, chlorine, bromine, alkyl, haloalkyl, alkoxy, haloalkoxy, alkenyl, haloalkenyl, alkenyloxy, haloalkenyloxy, aryl, halogenated aryl, aryloxy, halogenated aryloxy, substituted phosphate, substituted sulfonic acid, substituted imide, or substituted sulfonimide.

[0061] Cyclotriphosphazene compounds are a class of six-membered heterocyclic and conjugated phosphazene compounds with stable structures. The six-membered heterocyclic ring is composed of three N atoms and three P atoms connected by PN single and double bonds. Compared with linear phosphazene compounds, they have higher thermal stability. They are thermally decomposed at high temperatures to produce polyphosphoric acid and partial polyphosphoric acid, which cover the surface of the carbon layer and play a condensed phase flame retardant role. In addition, phosphorus oxygen free radicals and flame retardant gases (such as PO· and NH3) are also produced during the combustion process, which can terminate the free radical chain reaction and dilute the concentration of combustible gases, further slowing down the combustion and playing a gas phase flame retardant role. Adding cyclotriphosphazene compounds to the first region can better slow down the process of battery thermal runaway and delay the occurrence of severe thermal runaway.

[0062] In some embodiments, the substituents in the haloalkyl, haloalkoxy, haloalkenyl, haloalkenyloxy, haloaryl, and haloaryloxy groups are each independently selected from fluorine, chlorine, and bromine; the substituents in the substituted phosphate, substituted sulfonic acid, substituted imide, or substituted sulfonimide groups are each independently selected from alkyl, fluorine, chlorine, bromine, and the like.

[0063] In some embodiments, the cyclotriphosphazene compound includes at least one of hexafluorocyclotriphosphazene, hexachlorocyclotriphosphazene, methoxy (pentafluoro) cyclotriphosphazene, ethoxy (pentafluoro) cyclotriphosphazene, phenoxy (pentafluoro) cyclotriphosphazene, trifluoroethoxy (pentafluoro) cyclotriphosphazene, methylsulfonyl (pentafluoro) cyclotriphosphazene, or ethylsulfonyl (pentafluoro) cyclotriphosphazene.

[0064] The phosphorus atom in the cyclotriphosphazene is connected with different substituents, especially halogen atoms, through substitution reaction to form a combination of a phosphazene flame retardant and an organic halogen flame retardant, thereby achieving the purpose of synergistic flame retardancy; at least one of hexafluorocyclotriphosphazene, hexachlorocyclotriphosphazene, methoxy (pentafluoro) cyclotriphosphazene, ethoxy (pentafluoro) cyclotriphosphazene, phenoxy (pentafluoro) cyclotriphosphazene, trifluoroethoxy (pentafluoro) cyclotriphosphazene, methylsulfonate (pentafluoro) cyclotriphosphazene or ethylsulfonate (pentafluoro) cyclotriphosphazene is added to the first region, which can better slow down the process of thermal runaway of the battery and delay the occurrence of severe thermal runaway.

[0065] In some embodiments, the phosphate compound includes at least one of tris(chloroethyl)phosphate, tris(chloropropyl)phosphate, tris(dibromopropyl)phosphate, triphenyl phosphate, tricresyl phosphate, or tri-tert-butylphenyl phosphate.

[0066] By introducing halogen atoms into phosphate compounds, a combination of phosphate flame retardants and organic halogenated flame retardants can be formed to achieve the purpose of synergistic flame retardancy; by introducing benzene ring structures into phosphate compounds, the thermal stability of the flame retardant can be improved and the flame retardant effect can be improved; adding at least one of tris(chloroethyl) phosphate, tris(chloropropyl) phosphate, tris(dibromopropyl) phosphate, triphenyl phosphate, tricresyl phosphate or tri-tert-butylphenyl phosphate into the first region can better slow down the process of thermal runaway of the battery and delay the occurrence of severe thermal runaway.

[0067] In some embodiments, the organic halogenated compound includes at least one of decabromodiphenyl ether, tetrabromobisphenol A, tetrabromophthalic anhydride, pentabromotoluene, or hexabromocyclododecane.

[0068] In the present application, by adding at least one of decabromodiphenyl ether, tetrabromobisphenol A, tetrabromocatechol anhydride, pentabromotoluene or hexabromocyclododecane into the first region, since the above-mentioned organic halides have the advantages of small addition amount, strong flame retardancy and high thermal stability, the process of thermal runaway of the battery can be better slowed down and the occurrence of severe thermal runaway can be delayed.

[0069] In some embodiments, based on the total mass of the first region, the mass percentage of the flame retardant is ≤10%, and may be 3%-5%.

[0070] In the present application, the mass percentage of the flame retardant in the first region is ≤10%, for example 0.5%, 1%, 3%, 4%, 5%, 7%, 9%. Within this range, it is beneficial to further effectively slow down the process of thermal runaway, improve the safety performance of the battery, and ensure the low temperature performance and rate performance of the battery.

[0071] In some embodiments, based on the total mass of the first region, the mass percentage of the positive electrode active material is 86%-95%, and can be 91%-93%.

[0072] In the present application, the mass percentage of the positive electrode active material in the first region is 86%-95%, for example, 86.5%, 87%, 89%, 91%, 93%, 94%, 94.5%. Within this range, it is beneficial to further effectively slow down the process of thermal runaway, improve the battery safety performance while ensuring the low temperature performance and rate performance of the battery.

[0073] In some embodiments, the thickness of the first region is 5-50 μm, and optionally 20-30 μm.

[0074] In the present application, the thickness of the first region is 5-50μm, for example, 8μm, 10μm, 15μm, 20μm, 30μm, 40μm, 45μm. Within this range, it is beneficial to further effectively slow down the process of thermal runaway, improve the battery safety performance while ensuring the battery's low temperature performance and rate performance.

[0075] In some embodiments, the thickness of the second region is 50-100 μm, and optionally 65-85 μm.

[0076] In the present application, the thickness of the second region is 50-100μm, for example, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 90μm. Within this range, it is beneficial to further effectively slow down the process of thermal runaway, improve the battery safety performance while ensuring the battery's low temperature performance and rate performance.

[0077] In addition, the secondary battery, battery module, battery pack, and electric device of the present application will be described below with reference to the drawings as appropriate.

[0078] In one embodiment of the present application, a secondary battery is provided.

[0079] Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.

[0080] The positive electrode plate includes the positive electrode plate of the first aspect of the present application.

[0081] [Negative electrode]

[0082] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0083] 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.

[0084] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, 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.).

[0085] 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.

[0086] 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).

[0087] 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.

[0088] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0089] 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.

[0090] [Electrolytes]

[0091] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0092] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] [Isolation film]

[0097] In some embodiments, the secondary battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0098] 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.

[0099] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0100] In some embodiments, the secondary battery may include an outer package, which may be used to encapsulate the electrode assembly and the electrolyte.

[0101] 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.

[0102] The present application has no particular limitation on the shape of the secondary battery, which may be cylindrical, square or any other shape. Figure 3 The secondary battery 5 is a square structure as an example.

[0103] In some embodiments, reference Figure 4 , the outer packaging may include a shell 51 and a top cover assembly 53. Among them, the shell 51 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 51 has an opening connected to the receiving cavity, and the top cover assembly 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet 54, the negative electrode sheet and the isolation membrane can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0104] In some embodiments, secondary batteries may be assembled into a battery module. The number of secondary batteries contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

[0105] Figure 5 4 is an example of a battery module. Figure 5 In the battery module 4, the plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of secondary batteries 5 may be fixed by fasteners.

[0106] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of secondary batteries 5 are received in the receiving space.

[0107] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

[0108] Figure 6 and Figure 7 1 is a battery pack 1 as an example. Figure 6 and Figure 7The battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0109] In addition, the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device. The electrical device may include 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 are not limited thereto.

[0110] As the electrical device, a secondary battery, a battery module or a battery pack may be selected according to its usage requirements.

[0111] Figure 8 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the high power and high energy density requirements of the power consumption device for the secondary battery, a battery pack or a battery module can be used.

[0112] Another example of a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a secondary battery may be used as a power source.

[0113] Example

[0114] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0115] Example 1

[0116] The battery is prepared as follows:

[0117] Preparation of positive electrode:

[0118] Lithium cobalt oxide (LiCoO2), flame retardant hexafluorocyclotriphosphazene, conductive carbon black, and polyvinylidene fluoride were dispersed in nitrogen methyl pyrrolidone (NMP) at a ratio of 93%: 3%: 2%: 2% and stirred evenly to prepare a first positive electrode slurry with a solid content of 73%. The first positive electrode slurry was evenly coated on both sides of the aluminum foil, and the single-side coating surface density was 0.06g / 1540.25mm 2 , obtaining a first initial positive electrode film layer; dispersing lithium cobalt oxide (LiCoO2), conductive carbon black, and polyvinylidene fluoride in nitrogen methyl pyrrolidone at a ratio of 96%: 2%: 2% and stirring evenly to prepare a second positive electrode slurry with a solid content of 73%, and coating the second positive electrode slurry evenly on both sides of the first initial positive electrode film layer, with a single-side coating surface density of 0.18g / 1540.25mm 2 , obtain the second initial positive electrode film layer; then dry, cold press, and cut to form a positive electrode sheet with a thickness of 20 μm in the first region and a thickness of 65 μm in the second region (the positional relationship between the first region and the second region is shown in FIG. Figure 1 ).

[0119] Preparation of negative electrode sheet:

[0120] Graphite, conductive carbon black, sodium carboxymethyl cellulose, and polystyrene butadiene rubber were dispersed in deionized water at a ratio of 96%: 1%: 1%: 2% and stirred evenly to prepare a negative electrode slurry with a solid content of 48%, and then evenly coated on both sides of the copper foil. The single-side coating surface density was 0.12g / 1540.25mm 2 , and then dried, cold pressed, and cut to form negative electrode sheets with a negative electrode film thickness of 90μm.

[0121] Preparation of electrolyte:

[0122] Ethylene carbonate (EC), diethyl carbonate (DEC) and dimethyl carbonate (DMC) are mixed in a volume ratio of 5:2:3 at a temperature of 25° C. Then, lithium hexafluorophosphate is added thereto to prepare a 1.0 mol / L solution, which is the electrolyte.

[0123] The positive electrode sheet, the separator (polyethylene, 9 μm thick) and the negative electrode sheet are aligned and stacked in order, and then wound into a bare cell with a theoretical capacity of 20 Ah. The bare cell is assembled into a shell and injected with electrolyte. After chemical formation, a battery is obtained.

[0124] As shown in Table 1 below, the batteries of Examples 2-24 were prepared in the same manner as in Example 1 except that the product parameters of the positive electrode sheet were adjusted.

[0125] Comparative Example 1

[0126] The difference between Comparative Example 1 and Example 1 is that lithium cobalt oxide (LiCoO2), conductive carbon black, and polyvinylidene fluoride are dispersed in nitrogen methyl pyrrolidone in a ratio of 96%: 2%: 2% and stirred evenly to prepare a positive electrode slurry with a solid content of 73%. The positive electrode slurry is evenly coated on both sides of the aluminum foil, and the single-side coating surface density is 0.24g / 1540.25mm 2 ; Then drying, cold pressing and cutting are carried out to form positive electrode sheets with a positive electrode film thickness of 85 μm, and the rest are the same as in Example 1.

[0127] Comparative Example 2

[0128] Lithium cobalt oxide (LiCoO2), conductive carbon black, and polyvinylidene fluoride were dispersed in nitrogen methyl pyrrolidone at a ratio of 96%:2%:2% and stirred evenly to prepare a first positive electrode slurry with a solid content of 73%. The first positive electrode slurry was evenly coated on both sides of the aluminum foil, and the single-side coating surface density was 0.18g / 1540.25mm 2 , obtaining a first initial positive electrode film layer; dispersing lithium cobalt oxide (LiCoO2), flame retardant hexafluorocyclotriphosphazene, conductive carbon black, and polyvinylidene fluoride in a ratio of 93%:3%:2%:2% in nitrogen methyl pyrrolidone and stirring evenly to prepare a second positive electrode slurry with a solid content of 73%, and coating the second positive electrode slurry evenly on both sides of the first initial positive electrode film layer, with a single-side coating surface density of 0.06g / 1540.25mm 2 , obtaining a second initial positive electrode film layer; then drying, cold pressing, and cutting to form a positive electrode sheet with a thickness of 65 μm in the first region and a thickness of 20 μm in the second region, and the rest are the same as in Example 1.

[0129] The relevant parameters of the batteries of the above-mentioned Examples 1-24 and Comparative Examples 1-2 are shown in the following Table 1.

[0130] Table 1: Related parameter results of the batteries of Examples 1-24 and Comparative Examples 1-2

[0131]

[0132]

[0133] 2. Performance test:

[0134] Explanation of the battery testing method:

[0135] 1. Hot box test: Referring to GB / T 38031-2020 "Safety Requirements for Power Batteries for Electric Vehicles", a hot box test was performed on the batteries of each embodiment and comparative example. The specific test method is: the battery is charged to 4.45V at a constant current of 1C at 25°C, and then charged at a constant voltage until the current drops to 0.05C, and charging is stopped. The battery is then heated from room temperature to a set temperature in a temperature box at a heating rate of 5°C / min, and maintained at this temperature for 60 minutes. Observe whether it catches fire or explodes. If it does not catch fire or explode, it is considered to have passed the set temperature; increase the set temperature by 5°C as a gradient and test according to the above process until the battery fails (fire or explosion means failure), and the highest temperature passed is the highest passing temperature of the hot box test. The test results are shown in Table 2.

[0136] 2. Low temperature performance test: The batteries of each embodiment and comparative example were subjected to a low temperature performance test. The specific test method is as follows: at 25°C, the battery was charged to 4.45V at a constant current of 1C, and then charged at a constant voltage until the current dropped to 0.05C, and the charging was stopped. This capacity was recorded as the standard capacity of the battery. The battery was transferred to a -10°C incubator, left to stand for 2 hours, and then discharged to 3.0V at a constant current of 0.33C. This capacity was recorded as the low temperature discharge capacity. Low temperature performance = low temperature discharge capacity / standard capacity*100%. The test results are shown in Table 2.

[0137] 3. Rate performance test: The batteries of each embodiment and comparative example were subjected to rate performance test. The specific test method is as follows: the battery was charged to 4.45V at a constant current of 1C at 25°C, and then charged at a constant voltage until the current dropped to 0.05C, and the charging was stopped. This capacity was recorded as the standard capacity of the battery cell. At 25°C, the battery was discharged to 3.0V at a constant current of 2C, and this capacity was recorded as the discharge capacity. Rate performance = discharge capacity / standard capacity*100%. The test results are shown in Table 2.

[0138] The performance results of the batteries of Examples 1-24 and Comparative Examples 1-2 are shown in Table 2 below.

[0139] Table 2: Performance results of batteries of Examples 1-24 and Comparative Examples 1-2

[0140]

[0141]

[0142] According to the above results, compared with Comparative Example 1 in which no flame retardant is added, when a flame retardant is added to the first film layer in Examples 1-24, the maximum pass temperature of the hot box test can be significantly improved. That is, by adding a flame retardant in the first region, the process of thermal runaway can be effectively slowed down, and the occurrence of severe thermal runaway can be delayed, thereby improving the safety performance of the battery.

[0143] Compared with adding the flame retardant in the second region in Comparative Example 2, when the flame retardant is added in the first region in Example 1, the low temperature performance and rate performance of the battery are significantly improved; that is, by adding the flame retardant in the first region, the flame retardant can be prevented from complexing with the solvent in the electrolyte on the surface of the positive electrode film layer, thereby increasing the interfacial impedance, thereby further improving the low temperature performance and rate performance of the battery.

[0144] By comparing Examples 1-6, when the mass percentage of the flame retardant in the first region is the same, the cyclotriphosphazene flame retardant has better safety performance, low temperature performance and rate performance than the phosphate flame retardant and the organic halide flame retardant.

[0145] By comparing Examples 1 and 7-12, while ensuring that the low temperature performance and rate performance of the battery are not significantly deteriorated, when the mass percentage of the flame retardant in the first region is ≤10%, preferably 3%-5%, the battery has better safety performance, low temperature performance and rate performance.

[0146] By comparing Examples 1 and 13-17, the thickness of the first region is 5-50 μm, preferably 20-30 μm, and the battery has better safety performance, low temperature performance and rate performance.

[0147] By comparing Examples 1 and 18-22, the thickness of the second region is 50-100 μm, preferably 65-85 μm, and the battery has better safety performance, low temperature performance and rate performance.

[0148] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A positive electrode sheet, characterized in that: The invention comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, wherein the positive electrode film layer comprises a first region and a second region, and along the thickness direction of the positive electrode film layer, the first region is located between the positive electrode current collector and the second region; The first region includes a positive electrode active material and a flame retardant.

2. The positive electrode sheet according to claim 1, characterized in that: The flame retardant includes at least one of phosphazene compounds, phosphate compounds or organic halides.

3. The positive electrode sheet according to claim 2, characterized in that: The phosphazene compound includes a cyclotriphosphazene compound, and the cyclotriphosphazene compound includes a structural formula shown in formula (I): Wherein, R1, R2, R3, R4, R5 and R6 are each independently selected from one of fluorine, chlorine, bromine, alkyl, haloalkyl, alkoxy, haloalkoxy, alkenyl, haloalkenyl, alkenyloxy, haloalkenyloxy, aryl, halogenated aryl, aryloxy, halogenated aryloxy, substituted phosphate, substituted sulfonic acid, substituted imide or substituted sulfonimide.

4. The positive electrode sheet according to claim 3, characterized in that: The cyclotriphosphazene compound includes at least one of hexafluorocyclotriphosphazene, hexachlorocyclotriphosphazene, methoxy (pentafluoro) cyclotriphosphazene, ethoxy (pentafluoro) cyclotriphosphazene, phenoxy (pentafluoro) cyclotriphosphazene, trifluoroethoxy (pentafluoro) cyclotriphosphazene, methylsulfonate (pentafluoro) cyclotriphosphazene or ethylsulfonate (pentafluoro) cyclotriphosphazene.

5. The positive electrode sheet according to claim 2, characterized in that: The phosphate compound includes at least one of tris(chloroethyl)phosphate, tris(chloropropyl)phosphate, tris(dibromopropyl)phosphate, triphenyl phosphate, tricresyl phosphate or tri-tert-butylphenyl phosphate.

6. The positive electrode sheet according to claim 2, characterized in that: The organic halogenated compound includes at least one of decabromodiphenyl ether, tetrabromobisphenol A, tetrabromocatechol anhydride, pentabromotoluene or hexabromocyclododecane.

7. The positive electrode sheet according to any one of claims 1 to 6, characterized in that: Based on the total mass of the first region, the mass percentage of the flame retardant is ≤10%, and can be optionally 3%-5%.

8. The positive electrode sheet according to any one of claims 1 to 7, characterized in that: Based on the total mass of the first region, the mass percentage of the positive electrode active material is 86%-95%, and can be optionally 91%-93%.

9. The positive electrode sheet according to any one of claims 1 to 8, characterized in that: The thickness of the first region is 5-50 μm, and can be 20-30 μm.

10. The positive electrode sheet according to any one of claims 1 to 9, characterized in that: The thickness of the second region is 50-100 μm, and optionally 65-85 μm.

11. A battery, characterized in that: The invention comprises the positive electrode sheet according to any one of claims 1 to 10.

12. An electrical device, characterized in that: Comprising the battery of claim 11.

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