Secondary battery and positive electrode paste for secondary battery

Abstract

The present application provides a secondary battery and a positive electrode paste for the secondary battery. The secondary battery comprises a positive electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer provided on the positive electrode current collector, wherein the positive electrode film layer comprises at least one of a compound represented by formula A, a compound represented by formula B, and a compound represented by formula C. Formula A, formula B, formula C, where R1, R2 and R3 are each independently selected from a C2-4 alkylene group or alkenyl group, which is optionally substituted by a halogen, a C1-6 alkyl group or a C1-6 alkoxy group.

Description

Secondary batteries and positive electrode slurry for secondary batteries

[0001] Cross-referencing

[0002] This application incorporates Chinese Patent Application No. 202411487194.2, filed on October 23, 2024, entitled “Secondary Battery and Positive Electrode Slurry for Secondary Battery”, which is incorporated herein by reference in its entirety. Technical Field

[0003] This application relates to the field of secondary battery technology, and more particularly to a secondary battery and a positive electrode slurry for a secondary battery. Background Technology

[0004] In recent years, with the increasing demand for clean energy, secondary batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, transportation vehicles, military equipment, aerospace, and many other fields. As the application areas of secondary batteries have greatly expanded, higher requirements have been placed on their performance.

[0005] Rechargeable batteries possess advantages such as long cycle life, low cost, and high safety, making them a hot area of ​​development. However, the current energy density of rechargeable batteries is insufficient to meet the ever-increasing demands.

[0006] Therefore, there is a need to provide a secondary battery with a high battery energy density. Summary of the Invention

[0007] This application is made in view of the above-mentioned problems, and its purpose is to provide a secondary battery with a high battery energy density.

[0008] The inventors have discovered that by adopting the technical solution of this application, the above-mentioned objectives can be achieved.

[0009] The first aspect of this application provides a secondary battery, which includes a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive electrode film layer disposed on the positive current collector, wherein...

[0010] The positive electrode film includes at least one of the compounds shown in Formula A, Formula B, and Formula C.

[0011] Among them, R1, R2, and R3 are independently selected from: C 2-4 Alkylene or alkenylene, optionally with halogen, C 1-6 Alkyl or C 1-6 Alkyl-substituted.

[0012] The secondary battery of this application has a high battery energy density.

[0013] In any embodiment, the compaction density of the positive electrode sheet is >2.8 g / cc.

[0014] In any embodiment, the compaction density of the positive electrode sheet is from 2.9 g / cc to 3.1 g / cc.

[0015] When the compaction density of the positive electrode sheet is >2.8 g / cc or between 2.9 g / cc and 3.1 g / cc, the secondary battery of this application has a high battery energy density.

[0016] In any embodiment, the positive electrode film layer further includes at least one of the compounds represented by Formula I, Formula II, and Formula III.

[0017] Among them, R 11 R 21 R 31 Selected independently from: C 2-4 Alkylene or alkenylene, optionally with halogen, C 1-6 Alkyl or C 1-6 Alkyl-substituted.

[0018] When the positive electrode film layer further includes at least one of the compounds shown in Formula I, Formula II, and Formula III, the secondary battery of this application has improved storage gas generation performance.

[0019] In any embodiment, the positive electrode film layer comprises a compound represented by Formula A or a compound represented by Formula B.

[0020] When the positive electrode film layer includes the compound shown in Formula A or the compound shown in Formula B, the secondary battery of this application has improved storage gas generation performance.

[0021] In any embodiment, the positive electrode film layer includes at least one of the compounds shown in the following formula.

[0022] When the positive electrode film layer includes the above-mentioned compounds, the secondary battery of this application has a higher battery energy density and improved storage gas generation performance.

[0023] A second aspect of this application provides a positive electrode slurry for a secondary battery. The positive electrode slurry comprises a positive electrode active material and a positive electrode additive, wherein the positive electrode additive comprises at least one of the compounds shown in Formula I, Formula II, and Formula III.

[0024] Among them, R 11R 21 R 31 Selected independently from: C 2-4 Alkylene or alkenylene, optionally with halogen, C 1-6 Alkyl or C 1-6 Alkyl-substituted.

[0025] The positive electrode slurry of this application has improved stability after standing for 24 hours. The positive electrode sheet obtained by coating the positive electrode slurry of this application onto the positive electrode current collector and drying it has a high compaction density. The secondary battery containing this positive electrode sheet has a high battery energy density and also has improved storage gas generation performance.

[0026] In any embodiment, the positive electrode additive has the structure shown in Formula I or Formula II.

[0027] When the positive electrode additive has the structure shown in Formula I or Formula II, the positive electrode slurry of this application has improved stability after standing for 24 hours. A positive electrode sheet is obtained by coating the positive electrode slurry of this application onto the positive electrode current collector and drying it. The secondary battery containing the positive electrode sheet has improved storage gas generation performance.

[0028] In any embodiment, the positive electrode additive includes at least one of the compounds shown in the following formula.

[0029] When the positive electrode additive includes the above-mentioned compounds, the positive electrode slurry of this application has improved stability after standing for 24 hours. The positive electrode sheet obtained by coating the positive electrode slurry of this application onto the positive electrode current collector and drying it has a high compaction density, and the secondary battery containing the positive electrode sheet has a high battery energy density and also has improved storage gas generation performance.

[0030] In any embodiment, the weight ratio of the positive electrode active material to the positive electrode additive is 1000:1-20:1.

[0031] When the weight ratio of positive electrode active material to positive electrode additive is 1000:1-20:1, the positive electrode slurry of this application exhibits improved stability after standing for 24 hours. The positive electrode sheet obtained by coating the positive electrode slurry of this application onto the positive electrode current collector and drying it has a high compaction density, and the secondary battery containing this positive electrode sheet has a high battery energy density and also has improved storage gas generation performance.

[0032] In any embodiment, the positive electrode active material includes one or more of polyanionic compounds, transition metal oxides, and Prussian blue compounds.

[0033] In any embodiment, the positive electrode active material includes a transition metal oxide, and the transition metal oxide includes A. yQO2, where A is one or more of Li and Na, Q is one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, and 0 <y≤1。

[0034] A third aspect of this application provides a secondary battery comprising a positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive electrode film layer disposed on the positive current collector, the positive electrode film layer being obtained by coating and drying the positive electrode slurry of the second aspect of this application.

[0035] The fourth aspect of this application provides an electrical device that includes a secondary battery as described in the first or third aspect of this application. Attached Figure Description

[0036] Figure 1 is a schematic diagram of a secondary battery according to an embodiment of this application.

[0037] Figure 2 is an exploded view of a secondary battery according to an embodiment of this application shown in Figure 1.

[0038] Figure 3 is a schematic diagram of a battery module according to one embodiment of this application.

[0039] Figure 4 is a schematic diagram of a battery pack according to one embodiment of this application.

[0040] Figure 5 is an exploded view of the battery pack of one embodiment of this application shown in Figure 4.

[0041] Figure 6 is a schematic diagram of an electrical device using a secondary battery as a power source according to an embodiment of this application.

[0042] Explanation of reference numerals in the attached diagram: 1 Battery pack; 2 Upper casing; 3 Lower casing; 4 Battery module; 5 Secondary battery; 51 Housing; 52 Electrode assembly; 53 Top cover assembly Detailed Implementation

[0043] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the positive electrode slurry, secondary battery, preparation method thereof, and electrical device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0044] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0045] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0046] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0047] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0048] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0049] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0050] Rechargeable batteries possess advantages such as long cycle life, low cost, and high safety, making them a hot area of ​​development. However, the energy density of current rechargeable batteries is insufficient to meet the ever-increasing demands. Therefore, there is a need to provide a rechargeable battery with higher energy density.

[0051] Based on this, this application proposes a technical solution to solve the above-mentioned technical problems.

[0052] A first aspect of this application provides a secondary battery, the secondary battery comprising a positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive electrode film layer disposed on the positive current collector, wherein...

[0053] The positive electrode film layer includes at least one of the compounds represented by Formula A, Formula B, and Formula C.

[0054] Among them, R1, R2, and R3 are independently selected from: C 2-4 Alkylene or alkenylene, optionally with halogen, C 1-6 Alkyl or C 1-6 Alkyl-substituted.

[0055] The compounds shown in Formula A, Formula B, and Formula C are small molecule esters, which can plasticize the binder in the positive electrode sheet. While increasing the ultimate compaction density of the positive electrode sheet, they ensure that the brittleness of the electrode sheet meets the process requirements. Therefore, they can improve the compaction density of the positive electrode sheet, thereby enabling the secondary battery containing the positive electrode sheet to have a higher battery energy density.

[0056] In some embodiments, R1, R2, and R3 are independently selected from: ethylene, propylene, butylene, pentylene, vinylene, propenylene, butenylene, or pentylene, optionally converted by halogen, C 1-6 Alkyl or C 1-6 Alkyl-substituted.

[0057] In this application, there are no particular restrictions on halogens; for example, they can be fluorine, chlorine, bromine, and iodine.

[0058] In this application, C 1-6Examples of alkyl groups include, but are not limited to: methyl, ethyl, n-propyl, 1-methylethyl (isopropyl), n-butyl, tert-butyl, isopentyl, and n-hexyl.

[0059] In this application, C 1-6 Examples of alkoxy groups include, but are not limited to: methoxy, ethoxy, and propoxy.

[0060] In some implementations, the compaction density of the positive electrode sheet is >2.8 g / cc.

[0061] In some embodiments, the compaction density of the positive electrode sheet is from 2.9 g / cc to 3.1 g / cc.

[0062] When the compaction density of the positive electrode sheet is greater than 2.8 g / cc or between 2.9 g / cc and 3.1 g / cc, the increase in the compaction density of the positive electrode sheet leads to an increase in the volumetric energy density of the cell, thus the secondary battery of this application has a higher battery energy density.

[0063] In some embodiments, the positive electrode film layer further includes at least one of the compounds represented by Formula I, Formula II, and Formula III.

[0064] Among them, R 11 R 21 R 31 Selected independently from: C 2-4 Alkylene or alkenylene, optionally with halogen, C 1-6 Alkyl or C 1-6 Alkyl-substituted.

[0065] When the positive electrode film layer also includes at least one of the compounds shown in Formula I, Formula II, and Formula III, such compounds can undergo a ring-opening reaction with the alkali on the positive electrode to form a CEI film, suppressing side reactions on the positive electrode side and thus reducing gas generation during storage. Therefore, the secondary battery of this application has improved gas generation performance during storage.

[0066] In some implementations, R 11 R 21 R 31 The groups are independently selected from: ethylene, propyleneene, butylene, pentylene, vinylene, propenylene, butylene, or pentenylene, optionally converted by halogen, C 1-6 Alkyl or C 1-6 Alkyl-substituted.

[0067] In some embodiments, the positive electrode film layer comprises a compound represented by Formula A or a compound represented by Formula B.

[0068] When the positive electrode film layer includes the compound shown in Formula A or the compound shown in Formula B, the compound shown in Formula A or the compound shown in Formula B can plasticize the binder in the positive electrode sheet, ensuring that the brittleness of the positive electrode sheet meets the process requirements while increasing the ultimate compaction density of the positive electrode sheet. Therefore, the compaction density of the positive electrode sheet can be increased, thereby enabling the secondary battery containing the positive electrode sheet to have a higher battery energy density.

[0069] In some embodiments, the positive electrode film layer includes a compound represented by formula B, where R2 is propylene or propenylidene.

[0070] In some embodiments, the positive electrode film layer includes at least one of the compounds shown in the following formula.

[0071] When the positive electrode film layer includes the above-mentioned compound, the compound shown in Formula B can plasticize the binder in the positive electrode sheet, ensuring that the brittleness of the positive electrode sheet meets the process requirements while increasing the ultimate compaction density of the positive electrode sheet. Therefore, the compaction density of the positive electrode sheet can be increased, thereby enabling the secondary battery containing the positive electrode sheet to have a higher battery energy density.

[0072] A second aspect of this application provides a positive electrode slurry for a secondary battery, the positive electrode slurry comprising a positive electrode active material and a positive electrode additive, the positive electrode additive comprising at least one of a compound represented by Formula I, a compound represented by Formula II, and a compound represented by Formula III.

[0073] Among them, R 11 R 21 R 31 Selected independently from: C 2-4 Alkylene or alkenylene, optionally with halogen, C 1-6 Alkyl or C 1-6 Alkyl-substituted.

[0074] The aforementioned cyclic esters can consume residual alkali through a ring-opening reaction, preventing them from reacting with the binder PVDF and causing PVDF to lose HF and initiate chemical gelation. This improves the stability of the positive electrode slurry, resulting in improved stability of the positive electrode slurry after 24 hours (h). Positive electrode active materials in secondary batteries (e.g., sodium-ion batteries or lithium-ion batteries) have high residual alkali content. Positive electrode additives with structures shown in Formula I, II, and / or III can undergo a ring-opening reaction with residual alkali to generate small molecule esters (compounds shown in Formula A, Formula B, and / or Formula C). These small molecule esters can plasticize the binder in the positive electrode, ensuring that the brittleness of the electrode meets process requirements while increasing the ultimate compaction density of the positive electrode sheet. Therefore, the compaction density of the electrode sheet can be improved. Thus, the positive electrode sheet obtained by coating the positive electrode slurry of this application onto the positive electrode current collector and drying it has a high compaction density.

[0075] The compounds shown in Formula I, Formula II, and / or Formula III can undergo a ring-opening reaction with the alkali at the positive electrode to form a CEI film, suppressing side reactions on the positive electrode side and thus reducing gas generation during storage. Therefore, the secondary battery of this application has improved gas generation performance during storage.

[0076] In addition, while the ring-opening reaction consumes the alkali, the corresponding sodium or lithium salts generated provide the battery with excess active sodium or active lithium, thus resulting in an increase in cell capacity and leading to a higher battery energy density in the secondary battery.

[0077] In some embodiments, the compound represented by Formula I includes cyclic sulfate compounds. In some embodiments, the compound represented by Formula I includes one or more of vinyl sulfate, propylene sulfate, butenyl sulfate, pentenyl sulfate, ethane sulfate, propane sulfate, butane sulfate, and pentane sulfate.

[0078] In some embodiments, the compound represented by Formula II includes cyclic sulfonyl lactones. In some embodiments, the compound represented by Formula II includes one or more of ethane sulfonyl lactone, vinyl sulfonyl lactone, 1,3-propane sulfonyl lactone, 1,3-propene sulfonyl lactone, butane sulfonyl lactone, butene sulfonyl lactone, pentane sulfonyl lactone, and pentene sulfonyl lactone.

[0079] In some embodiments, the compound represented by Formula III includes cyclic carbonate compounds. In some embodiments, the compound represented by Formula III includes one or more of the following: vinylene carbonate, halogenated vinylene carbonate, ethylene ethylene carbonate, propylene carbonate, halogenated propylene carbonate, propylene ethylene carbonate, butene carbonate, halogenated butene carbonate, butene ethylene carbonate, penelenene carbonate, halogenated penelen carbonate, and penelenene ethylene carbonate.

[0080] In some implementations, R 11 R 21 R 31 The groups are independently selected from: ethylene, propyleneene, butylene, pentylene, vinylene, propenylene, butylene, or pentenylene, optionally converted by halogen, C 1-6 Alkyl or C 1-6 Alkyl-substituted.

[0081] In some embodiments, the positive electrode additive has the structure shown in Formula I or Formula II.

[0082] When the positive electrode additive has the structure shown in Formula I or Formula II, it consumes the residual alkali by undergoing a ring-opening reaction with the residual alkali, avoiding the reaction between the positive electrode binder PVDF and the residual alkali leading to the removal of HF and initiation of chemical gelation, thus improving the stability of the positive electrode slurry. As a result, the positive electrode slurry of this application has improved stability after standing for 24 hours.

[0083] The positive electrode active material of a secondary battery has a high residual alkali content. Positive electrode additives with structures shown in Formula I and / or Formula II can undergo ring-opening reactions with the residual alkali to generate small-molecule esters (compounds shown in Formula A and / or Formula B). These small-molecule esters can plasticize the binder in the positive electrode, ensuring that the brittleness of the electrode meets process requirements while increasing the ultimate compaction density, thus improving the compaction density of the electrode. Therefore, the positive electrode obtained by coating the positive electrode slurry of this application onto the positive electrode current collector and drying it has a high compaction density, thereby improving the energy density of the battery.

[0084] The compounds shown in Formula I and / or Formula II can undergo a ring-opening reaction with the alkali at the positive electrode to form a CEI film, suppressing side reactions on the positive electrode side and thus reducing gas generation during storage. Therefore, the secondary battery of this application has improved gas generation performance during storage.

[0085] In addition, while the ring-opening reaction consumes the alkali, the corresponding sodium or lithium salts generated provide the battery with excess active sodium or active lithium, thus resulting in an increase in cell capacity and leading to a higher battery energy density in the secondary battery.

[0086] In some embodiments, the positive electrode additive has the structure shown in Formula II, R 21 It is propylene or propenylidene.

[0087] In some embodiments, the positive electrode additive includes at least one of the compounds shown in the following formula.

[0088] When the cathode additive includes the above-mentioned compounds, the cathode additive has a stronger ability to undergo ring-opening reactions. This is determined by the number of atoms in the ring structure; the smaller the ring, the greater the ring-opening strain, and the easier it is to undergo ring-opening reactions with residual alkali. When R 21 When the compound is propylene or propene, the ring strain is greater, making ring-opening easier. As mentioned above, the 24-hour stability of the positive electrode slurry, the compaction density of the positive electrode sheet, the storage gas generation performance of the secondary battery, and the battery energy density are all positively correlated with the ability of the positive electrode additive to open the ring and react with residual alkali. Therefore, when the positive electrode additive includes the above-mentioned compounds, the positive electrode slurry of this application has improved 24-hour stability. The positive electrode sheet obtained by coating the positive electrode slurry of this application onto the positive electrode current collector and drying it has a high compaction density, and the secondary battery containing this positive electrode sheet has a high battery energy density and also has improved storage gas generation performance.

[0089] In some embodiments, the weight ratio of the positive electrode active material to the positive electrode additive is 1000:1-20:1.

[0090] When the weight ratio of positive electrode active material to positive electrode additive is 1000:1-20:1, by controlling the appropriate amount of addition, the stability of the positive electrode slurry after 24 hours of standing is improved, while not occupying too much of the main material, thus avoiding affecting the cell capacity. Within this weight ratio range, the positive electrode slurry of this application has improved stability after 24 hours of standing. The positive electrode sheet obtained by coating the positive electrode slurry of this application onto the positive electrode current collector and drying it has a high compaction density. The secondary battery containing this positive electrode sheet has a high battery energy density and also has improved storage gas generation performance.

[0091] In some embodiments, the weight ratio of the positive electrode active material to the positive electrode additive is 1000:1 to 100:1.

[0092] In some embodiments, the weight ratio of the positive electrode active material to the positive electrode additive is 1000:1, 000:1, 900:1, 800:1, 700:1, 600:1, 500:1, 400:1, 200:1, 100:1, 90:1, 80:1, 70:1, 60:1, 50:1, 40:1, 30:1, 20:1, or a range of any two of the above ratios or a ratio within that range.

[0093] In some embodiments, the positive electrode active material includes one or more of polyanionic compounds, transition metal oxides, and Prussian blue compounds.

[0094] In any embodiment, the positive electrode active material includes a transition metal oxide, wherein the transition metal oxide includes A. y QO2, where A is one or more of Li and Na, Q is one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, and 0 <y≤1。

[0095] A third aspect of this application provides a secondary battery comprising a positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive electrode film layer disposed on the positive current collector, the positive electrode film layer being obtained by coating and drying the positive electrode slurry described in the second aspect of this application.

[0096] The fourth aspect of this application provides an electrical device that includes the secondary battery described in the first or third aspect of this application.

[0097] In addition, the secondary battery and power-consuming device of this application will be described below with appropriate reference to the accompanying drawings.

[0098] In one embodiment of this application, a secondary battery is provided.

[0099] Typically, a secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0100] [Positive electrode plate]

[0101] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including a positive electrode active material.

[0102] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0103] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0104] In some embodiments, the positive electrode active material may include one or more of polyanionic compounds, transition metal oxides, and Prussian blue compounds.

[0105] In some embodiments, the positive electrode active material may include a transition metal oxide, wherein the transition metal oxide includes A y QO2, where A is one or more of Li and Na, Q is one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, and 0 <y≤1。

[0106] In some embodiments, the polyanionic compound may include sodium vanadium trifluorophosphate Na3V2(PO4)2F3, sodium vanadium fluorophosphate NaVPO4F, sodium vanadium phosphate Na3V2(PO4)3, Na4Fe3(PO4)2P2O7, NaFePO4, Na3V2(PO4)3, disodium pyrophosphate Na2Q1P2O7 (Q1 = Fe, Co, Mn), mixed pyrophosphate Na4Q23(PO4)2P2O7 (Q2 = Fe, Co, Mn, Ni), and one or more of the corresponding lithium salts. In some embodiments, the Prussian blue compound may be NazE. 1 E 2 (CN)6 or LizE 1 E 2 (CN)6, where E 1 E 2 It is one or more of Fe, Mn, Co, Ni, Cu, Zn, Cr, Ti, V, Zr, and Ce, where 0 < z ≤ 2.

[0107] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0108] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0109] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0110] [Negative electrode plate]

[0111] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0112] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0113] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0114] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and sodium 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, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0115] In some embodiments, the negative electrode film layer may optionally 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).

[0116] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0117] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0118] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0119] [Electrolytes]

[0120] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or entirely solid.

[0121] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0122] In some embodiments, the electrolyte salt may be selected from at least one of sodium hexafluorophosphate, sodium tetrafluoroborate, sodium perchlorate, sodium hexafluoroarsenate, sodium difluorosulfonylimide, sodium difluoromethanesulfonylimide, sodium trifluoromethanesulfonate, sodium difluorophosphate, sodium difluorooxalate borate, sodium dioxalate borate, sodium difluorodioxalate phosphate, sodium tetrafluorooxalate phosphate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium difluorosulfonylimide, lithium difluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium dioxalate borate, and lithium tetrafluorooxalate phosphate.

[0123] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0124] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0125] [Isolation membrane]

[0126] In some embodiments, the secondary battery also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0127] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0128] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0129] In some embodiments, the secondary battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0130] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the secondary battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0131] This application does not impose any particular limitation on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 shows a square-structured secondary battery 5 as an example.

[0132] In some embodiments, referring to FIG2, the outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be placed over the opening to close the receiving cavity. A positive electrode, a negative electrode, and a separator can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The secondary battery 5 may contain one or more electrode assemblies 52, which can be selected by those skilled in the art according to specific practical needs.

[0133] In some implementations, the secondary batteries can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0134] Figure 3 shows a battery module 4 as an example. Referring to Figure 3, in the battery module 4, multiple secondary batteries 5 can be arranged sequentially along the length of the battery module 4. Of course, they can also be arranged in any other manner. Furthermore, the multiple secondary batteries 5 can be fixed in place using fasteners.

[0135] Optionally, the battery module 4 may also include a housing with a receiving space in which a plurality of secondary batteries 5 are received.

[0136] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0137] Figures 4 and 5 show a battery pack 1 as an example. Referring to Figures 4 and 5, the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper box 2 and a lower box 3, with the upper box 2 covering the lower box 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0138] In addition, this application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in this application. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., 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.

[0139] As the electrical device, a secondary battery, battery module, or battery pack can be selected according to its usage requirements.

[0140] Figure 6 shows an example of an electrical device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the secondary battery for this device, a battery pack or battery module can be used.

[0141] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a rechargeable battery as their power source.

[0142] Example

[0143] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0144] I. Preparation Method

[0145] Example 1

[0146] (1) Preparation of the positive electrode sheet:

[0147] The positive electrode active material (NaMn) 0.4 Ni 0.6 O2), conductive carbon black, carbon nanotubes, binder polyvinylidene fluoride (PVDF), and 1,3-propane sulpholol were mixed with N-methylpyrrolidone (NMP) in a weight ratio of 95.5:1.8:0.4:1.8:0.5 to obtain a positive electrode slurry with a solid content of 65%. The positive electrode slurry was then mixed at a ratio of 0.356 g / 1540.25 mm². 2 The single-sided weight of the coating is applied to the aluminum foil. After coating, the foil is dried, cold-pressed, and cut to obtain the positive electrode sheet.

[0148] (2) Preparation of negative electrode sheet:

[0149] Hard carbon (negative electrode active material), carbon black (conductive agent), carboxymethyl cellulose (thickener), and styrene-butadiene rubber (binder) were added to deionized water at a mass ratio of 97:0.5:0.5:2 and stirred until homogeneous to obtain a negative electrode slurry. Then, the negative electrode slurry was prepared at a concentration of 0.157 g / 1540.25 mm. 2 The weight is evenly coated on both sides of the copper foil. After the double-sided coating is completed, it is dried, cold-pressed, and cut to obtain the negative electrode sheet.

[0150] (3) Separating membrane:

[0151] A polyethylene film with a thickness of 13 micrometers (μm) was used as the isolation membrane.

[0152] (4) Electrolyte:

[0153] Ethylene carbonate, diethyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 1:1:1. NaPF6 was then dissolved in this solution to obtain the electrolyte. The concentration of NaPF6 in the electrolyte was 1 mol / L.

[0154] (5) Battery fabrication:

[0155] The electrodes are arranged in the order of "diaphragm-negative electrode-diaphragm-positive electrode". One end of the positive electrode, negative electrode, and two diaphragms is fixed to the discharge roller, and the other end is stacked together and fixed to the winding shaft. The winding shaft is rotated by a motor to wind the positive electrode, negative electrode, and two diaphragms. After vacuum baking, liquid injection, sealing, formation, and capacity testing, the soft-pack battery cells are obtained in the lower compartment.

[0156] Examples 2-6, Comparative Examples 1-2

[0157] The main differences between Examples 2-6 and Comparative Examples 1-2 and Example 1 are shown in Table 1 below.

[0158] II. Testing Methods

[0159] 1. Determination of the ultimate compaction density of the positive electrode sheet

[0160] The double-coated positive electrode sheets are cold-pressed according to different compaction densities. Then, the positive electrode sheets with different compaction densities are cut into strips. The strips are folded in half and then pressed with a roller. The light is observed at the fold line to see if the aluminum foil is transparent. If it is, it is recorded as one light transmission. If it is not transparent, the electrode sheet is folded back along the original fold line and pressed with a roller again to see if the light is transparent at the fold line. The above steps are repeated until the aluminum foil is transparent at the fold line. The number of light transmissions is recorded. Generally, more than 3 light transmissions are acceptable. The maximum compaction density of the electrode sheet at this time is the ultimate compaction density.

[0161] The method for measuring compaction density is as follows: Dry the positive electrode sheet at room temperature. Then, measure the thickness of the positive electrode sheet using a micrometer and record it as d0 (unit: cm). The weight of a small round piece with a diameter of 14 mm is recorded as w0 (unit: g; 10 pieces are punched together and weighed, then the average weight is taken). Next, take a portion of the positive electrode sheet, wash away the film layer with water, and dry it. Measure the thickness of the aluminum foil substrate and record it as d1 (unit: cm). The weight of a small round piece with a diameter of 14 mm is recorded as w1 (unit: g; 10 pieces are punched together and weighed, then the average weight is taken). The compaction density of the positive electrode sheet is calculated as: Compaction Density PD = (w0 - w1) / ((d0 - d1) × 1.5386) (unit: g / cm³). 3 ).

[0162] 2. Determination of the stability of the positive electrode slurry after standing for 24 hours

[0163] Start timing from the end of stirring the positive electrode slurry and let it stand. After 24 hours of standing, test the viscosity of the slurry and use a spoon to scoop out the slurry and let it flow back into the cup. Observe the flow state of the slurry and take pictures to record it.

[0164] 3. Determination of gas production during storage at 60℃

[0165] First, discharge the prismatic battery at 0.33C to 1.5V at 25℃, then let it stand for 5 minutes, charge it at 0.33C to 4.15V, then charge it at a constant voltage until the current is less than 0.05C, let it stand for 5 minutes, and then discharge it at 0.33C to 1.5V. Record the battery capacity at this time as C0.

[0166] The obtained prismatic battery was first charged at 0.33C to 4.15V at 25℃, and then charged at constant voltage until the current was less than 0.05C. The volume of the soft pack at this time was measured as Q0. After that, it was placed in a temperature environment of 60℃ for storage test. The volume of the soft pack was measured every 10 days and recorded as Q. After a certain number of days of storage, the gas production per unit capacity was (Q-Q0) / C0.

[0167] 4. Measurement of battery energy density

[0168] Volumetric energy density = (cell capacity × average voltage / cell volume). Cell capacity is determined by the maximum number of cathodes and anodes that can be placed within the current cell size when the control margin is less than 93%. When the cathode compaction density increases, the cathode thickness decreases, allowing more cathodes and anodes to be placed in the same cell casing, resulting in higher cell capacity and higher volumetric energy density.

[0169] 5. Determination of the compound represented by formula A

[0170] X-ray photoelectron spectroscopy (XPS) can be performed on the surface of cold-pressed positive electrode sheets: the sample surface is irradiated with X-rays of specific energy, and the excited photoelectrons have fixed binding energies and are collected by a detector. The binding energies and chemical shifts of sulfur (S), oxygen (O), or carbon (C) elements can be analyzed to identify the elemental composition and chemical state of the compound.

[0171] 6. Determination of the compound represented by formula B

[0172] X-ray photoelectron spectroscopy (XPS) can be performed on the surface of cold-pressed positive electrode sheets: the sample surface is irradiated with X-rays of specific energy, and the excited photoelectrons have fixed binding energies and are collected by a detector. The binding energies and chemical shifts of sulfur (S), oxygen (O), or carbon (C) elements can be analyzed to identify the elemental composition and chemical state of the compound.

[0173] 7. Determination of the compound represented by formula C

[0174] X-ray photoelectron spectroscopy (XPS) can be performed on the surface of cold-pressed positive electrode sheets: the sample surface is irradiated with X-rays of specific energy, and the excited photoelectrons have fixed binding energies and are collected by a detector. The binding energies and chemical shifts of sulfur (S), oxygen (O), or carbon (C) elements can be analyzed to identify the elemental composition and chemical state of the compound.

[0175] 8. Determination of compounds represented by Formula I

[0176] X-ray photoelectron spectroscopy (XPS) can be performed on the surface of cold-pressed positive electrode sheets: the sample surface is irradiated with X-rays of specific energy, and the excited photoelectrons have fixed binding energies and are collected by a detector. The binding energies and chemical shifts of sulfur (S), oxygen (O), or carbon (C) elements can be analyzed to identify the elemental composition and chemical state of the compound.

[0177] 9. Determination of the compound represented by Formula II

[0178] X-ray photoelectron spectroscopy (XPS) can be performed on the surface of cold-pressed positive electrode sheets: the sample surface is irradiated with X-rays of specific energy, and the excited photoelectrons have fixed binding energies and are collected by a detector. The binding energies and chemical shifts of sulfur (S), oxygen (O), or carbon (C) elements can be analyzed to identify the elemental composition and chemical state of the compound.

[0179] 10. Determination of the compound represented by Formula III

[0180] X-ray photoelectron spectroscopy (XPS) can be performed on the surface of cold-pressed positive electrode sheets: the sample surface is irradiated with X-rays of specific energy, and the excited photoelectrons have fixed binding energies and are collected by a detector. The binding energies and chemical shifts of sulfur (S), oxygen (O), or carbon (C) elements can be analyzed to identify the elemental composition and chemical state of the compound.

[0181] 11. Determination of the compaction density of the positive electrode sheet of a BOL battery

[0182] After fully discharging the BOL battery, disassemble it. The full discharge process is as follows: discharge at a constant current of 0.1C to 1.5V. Then, dry the disassembled cathode at room temperature. Measure the thickness of the positive electrode sheet using a multimeter and record it as d0 (in cm). Calculate the weight of a small round piece with a diameter of 14mm and record it as w0 (in g; weigh 10 pieces together and take the average weight). Then, take a portion of the positive electrode sheet, wash off the film layer with water, and dry it. Measure the thickness of the aluminum foil substrate and record it as d1 (in cm). Calculate the weight of a small round piece with a diameter of 14mm and record it as w1 (in g; weigh 10 pieces together and take the average weight). The compaction density of the positive electrode sheet is calculated as PD = (w0 - w1) / ((d0 - d1) × 1.5386) (in g / cm³). 3 ).

[0183] 12. Determination of the compaction density of the positive electrode sheet after 100 battery cycles

[0184] After cycling 100 times, the battery was fully discharged and then disassembled. The full discharge process was as follows: Discharged at a constant current of 0.1C to 1.5V. The disassembled cathode was then dried at room temperature. The thickness of the positive electrode sheet was measured using a multimeter and recorded as d0 (in cm). The weight of a small round piece with a diameter of 14mm was recorded as w0 (in g; 10 pieces were punched together and weighed, and the average weight was taken). A portion of the positive electrode sheet was then washed with water to remove the film layer and dried. The thickness of the aluminum foil substrate was measured and recorded as d1 (in cm). The weight of a small round piece with a diameter of 14mm was recorded as w1 (in g; 10 pieces were punched together and weighed, and the average weight was taken). The compaction density of the positive electrode sheet was calculated as PD = (w0 - w1) / ((d0 - d1) × 1.5386) (in g / cm³). 3 ).

[0185] III. Analysis of Test Results for Each Embodiment and Comparative Example

[0186] Secondary batteries for each embodiment and comparative example were prepared according to the above method, and their performance was measured. The relevant parameters are shown in Table 1.

[0187] Table 1: Relevant parameters of the examples and comparative examples

[0188] Based on the above results, it can be seen that the secondary batteries in Examples 1-6 all include a positive electrode sheet, wherein the positive electrode sheet includes a positive current collector and a positive electrode film layer disposed on the positive current collector, wherein...

[0189] The positive electrode film layer includes at least one of the compounds represented by Formula A, Formula B, and Formula C.

[0190] Among them, R1, R2, and R3 are independently selected from: C 2-4 Alkylene or alkenylene, optionally with halogen, C 1-6 Alkyl or C 1-6 Alkoxy substitution,

[0191] The positive electrode slurries in Examples 1-6 all contain positive electrode active materials and positive electrode additives, wherein the positive electrode additives include at least one of the compounds shown in Formula I, Formula II, and Formula III.

[0192] Among them, R 11 R 21 R 31 Selected independently from: C 2-4 Alkylene or alkenylene, optionally with halogen, C 1-6 Alkyl or C 1-6 Alkyl-substituted.

[0193] As can be seen from the comparison between Examples 1-6 and Comparative Examples 1-2, the positive electrode slurry of this application has improved stability after standing for 24 hours. The positive electrode sheet obtained by coating the positive electrode slurry of this application onto the positive electrode current collector and drying it has a high compaction density. The secondary battery of this application has a high battery energy density and also has improved storage gas generation performance.

[0194] A comparison of Examples 1-3 and Example 4 shows that when the positive electrode film layer includes a compound represented by Formula A or Formula B, or when the positive electrode additive has the structure represented by Formula I or Formula II, the positive electrode slurry of this application has improved stability after standing for 24 hours. The secondary battery of this application has improved gas generation performance during storage.

[0195] A comparison of Examples 1-2 and Examples 3-4 shows that when the positive electrode film layer includes At least one of the compounds shown, or the positive electrode additive includes When at least one of the compounds shown is present, the positive electrode slurry of this application exhibits improved stability after standing for 24 hours. The positive electrode sheet obtained by coating the positive electrode slurry of this application onto the positive electrode current collector and drying it has a high compaction density. The secondary battery of this application has a high battery energy density and also has improved storage gas generation performance.

[0196] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A secondary battery, the secondary battery comprising a positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive electrode film layer disposed on the positive current collector, wherein, The positive electrode film layer includes at least one of the compounds represented by Formula A, Formula B, and Formula C. Among them, R1, R2, and R3 are independently selected from: C 2-4 Alkylene or alkenylene, optionally with halogen, C 1-6 Alkyl or C 1-6 Alkyl-substituted.

2. The secondary battery according to claim 1, wherein, The compaction density of the positive electrode sheet is >2.8 g / cc.

3. The secondary battery according to claim 1, wherein, The compaction density of the positive electrode sheet is 2.9 g / cc to 3.1 g / cc.

4. The secondary battery according to any one of claims 1-3, wherein, The positive electrode film layer further includes at least one of the compounds represented by Formula I, Formula II, and Formula III. Among them, R 11 R 21 R 31 Selected independently from: C 2-4 Alkylene or alkenylene, optionally with halogen, C 1-6 Alkyl or C 1-6 Alkyl-substituted.

5. The secondary battery according to any one of claims 1-4, wherein, The positive electrode film layer includes a compound represented by Formula A or a compound represented by Formula B.

6. The secondary battery according to any one of claims 1-5, wherein, The positive electrode film layer includes at least one of the compounds shown in the following formula.

7. A positive electrode slurry for a secondary battery, the positive electrode slurry comprising a positive electrode active material and a positive electrode additive, the positive electrode additive comprising at least one of a compound represented by Formula I, a compound represented by Formula II, and a compound represented by Formula III. in, R 11 R 21 R 31 Selected independently from: C 2-4 Alkylene or alkenylene, optionally with halogen, C 1-6 Alkyl or C 1-6 Alkyl-substituted.

8. The positive electrode slurry according to claim 7, wherein, The positive electrode additive has the structure shown in Formula I or Formula II.

9. The positive electrode slurry according to claim 7 or 8, wherein, The positive electrode additive includes at least one of the compounds shown in the following formula.

10. The positive electrode slurry according to any one of claims 7-9, wherein, The weight ratio of the positive electrode active material to the positive electrode additive is 1000:1-20:

1.

11. The positive electrode slurry according to any one of claims 7-10, wherein, The positive electrode active material includes one or more of polyanionic compounds, transition metal oxides, and Prussian blue compounds.

12. The positive electrode slurry according to any one of claims 7-11, wherein, The positive electrode active material includes a transition metal oxide, which includes A. y QO2, where A is one or more of Li and Na, Q is one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, and 0 <y≤1。 13. A secondary battery comprising a positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive electrode film layer disposed on the positive current collector, the positive electrode film layer being obtained by coating and drying the positive electrode slurry according to any one of claims 7-12.

14. An electrical device comprising a secondary battery according to any one of claims 1-6 or the secondary battery according to claim 13.

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