Positive electrode active material, method for manufacturing the same, lithium-ion battery containing the same, battery module, battery pack, and power consumption device

Abstract

The present application provides a positive electrode active material, and by coating the surface of a first lithium salt with a coating layer containing a second lithium salt, it can not only prevent the corrosion decomposition of the first lithium salt by the electrolyte, but also allows the second lithium salt to form a CEI film in situ on the surface of the first lithium salt particles, thereby improving the film structure and avoiding the decomposition of the active ingredient in the electrolyte, and the second lithium salt simultaneously contains fluorine and phosphorus elements, and the film composition formed is as consistent as possible with the film composition formed from lithium hexafluorophosphate in the electrolyte, thereby reducing the active lithium consumption in the electrolyte. The positive electrode active material of the present application can greatly improve the power performance and cycle life of the battery.

Description

[Technical Field]

[0001] [Cross-reference of related applications] This application claims priority to Chinese Patent Application No. 202111291132.0, filed on November 2, 2021, entitled “Positive electrode active material, method for manufacturing the same, lithium-ion battery containing the same, battery module, battery pack and power consumption device,” all contents of which are incorporated herein by reference.

[0002] This application relates to the field of electrochemistry, and more particularly to positive electrode active materials, lithium-ion batteries containing them, battery modules, battery packs, and power consumption devices. [Background technology]

[0003] With the rapid development of the new energy sector, lithium-ion batteries are widely applied in various large-scale power units, energy storage systems, and consumer products due to their superior electrochemical performance, lack of memory effect, and low environmental pollution. They are particularly widely used in the new energy vehicle sector, such as pure electric vehicles and hybrid electric vehicles. As a result, there is a growing demand for overall improvements in the lifespan and rapid charging performance of lithium-ion batteries. [Overview of the project]

[0004] This application has been made in view of the above-mentioned problems, and aims to provide a positive electrode active material that achieves both excellent power performance and cycle life in lithium-ion batteries.

[0005] A first aspect of this application provides a positive electrode active material comprising a substrate and a coating layer located on the surface of the substrate, wherein the substrate comprises a first lithium salt, and the first lithium salt comprises a layered structure of LiAO2, Li[Ni a Co b Mn c O2, and lithium-rich manganese systems xLi2MnO3·(1-x)LiMn y Z 1-yis at least one selected from O2, wherein A is Ni, Co, Mn or Al, and the Z is one or two metal ions selected from Ni, Co or Al, and 0.1≦x≦0.9, 0.1≦y≦0.9, 0<a<1, 0<b<1, 0<c<1, a+b+c=1. The coating layer comprises a second lithium salt simultaneously containing fluorine, phosphorus and oxygen, and oxygen in the second lithium salt contains lone electron pairs.

[0006] In any embodiment, based on the total mass of the positive electrode active material, the mass percentage of the second lithium salt is 0.1% to 20%, and optionally 1% to 10%.

[0007] In any embodiment, the thickness of the coating layer of the positive electrode active material is 10 to 100 nm, and optionally 20 to 60 nm.

[0008] In any embodiment, the second lithium salt is at least one selected from lithium difluorophosphate, lithium difluorobis(oxalato) phosphate, and lithium tetrafluoro(oxalato) phosphate.

[0009] In any embodiment, the positive electrode active material consists of first particles having a volume average particle diameter Dv50 of 2 to 8 µm and second particles having a volume average particle diameter Dv50 of 13 to 22 µm.

[0010] In any embodiment, the mass ratio of the first particles to the second particles is 2.3 to 9:1.

[0011] In any embodiment, the first and / or second particles simultaneously comprise two crystal forms of single crystal and polycrystal, and the mass ratio of single crystal particles to polycrystal particles is 0.1 to 1:1, and optionally 0.23 to 0.67:1.

[0012] A second aspect of the present application provides a method for producing a positive electrode active material, the method comprising: Step S1 of drying and dehydrating a first lithium salt to obtain the dried first lithium salt, Step S2 of dissolving a second lithium salt in an organic solvent to obtain a second lithium salt organic solution, Step S3 of adding the dried first lithium salt to the second lithium salt organic solution and uniformly mixing the same, Step S4 of filtering the uniformly mixed mixture, heat-treating the filtered solid particles to obtain the positive electrode active material comprising a substrate and a coating layer located on the surface of the substrate, the substrate comprises a first lithium salt, and the first lithium salt is selected from LiAO4 with a spinel structure, Li Z O2 with a layered structure and lithium-rich manganese-based xLi2MnO3·(1-x)LiCO2, wherein A is Ni or Co, and the Z is Ni, Co, Mn or Al, C is selected from Ni, Co or Mn and 0.1<x<0.9, and the coating layer comprises a second lithium salt containing both fluorine and phosphorus.

[0013] In any one of the embodiments, before step S1, step S0 is further comprised, and said step S0 comprises the step of producing a single-crystal first lithium salt and / or a polycrystalline first lithium salt.

[0014] In any one of the embodiments, step S5 is further comprised, and said step S5 is adjusting the volume average particle diameter Dv50 of the positive electrode active material to obtain first particles having a volume average particle diameter Dv50 of 2 to 8 µm and second particles having a volume average particle diameter Dv50 of 13 to 22 µm.

[0015] In any one of the embodiments, step S6 is further comprised, and said step S6 comprises mixing the first particles and the second particles at a predetermined mass ratio to obtain the positive electrode active material.

[0016] In any one of the embodiments, in said S1, the temperature range for drying and dehydrating said first lithium salt is 100-200°C, and / or, In S2, the organic solvent is an ether-based, carboxylic acid ester-based, or carbonate-based organic solvent, and / or In S3, the method for uniform mixing is to disperse by stirring at 50-100°C for 4-8 hours, and / or In S4, the heat treatment method is to treat in an air atmosphere at 200-250°C for 5-10 hours.

[0017] A third aspect of this application provides a lithium-ion battery comprising a high-nickel ternary cathode active material described in the first aspect of this application or a high-nickel ternary cathode active material manufactured by a manufacturing method according to the second aspect of this application.

[0018] A fourth aspect of this application provides a battery module, which includes a lithium-ion battery according to a third aspect of this application. The manufacture of the battery module can employ known methods in the prior art for manufacturing battery modules.

[0019] A fifth aspect of this application provides a battery pack comprising one or more lithium-ion batteries according to the third aspect of this application or battery modules according to the fourth aspect of this application. The manufacture of the battery pack can employ known methods in the prior art for manufacturing battery packs.

[0020] A sixth aspect of this application provides a power consumption device comprising one or more of the lithium-ion battery of the third aspect of this application, the battery module of the fourth aspect of this application, or the battery pack of the fifth aspect of this application, wherein the lithium-ion battery, the battery module, or the battery pack is used as a power source for the power consumption device or as an energy storage unit for the power consumption device. The manufacture of the power consumption device can employ known methods in the prior art for manufacturing power consumption devices.

[0021] [Beneficial effects] By coating the surface of the first lithium salt of this application with a coating layer containing a second lithium salt, on the one hand, corrosion decomposition of the first lithium salt by the electrolyte can be prevented, and the occurrence of side reactions can be reduced. On the other hand, the second lithium salt can form a CEI (cathode electrolyte interface) film in situ on the surface of the first lithium salt particles, thereby improving the film structure and avoiding the decomposition of the active ingredients in the electrolyte. Furthermore, the second lithium salt contains both fluorine and phosphorus, and the resulting film component is made to match the CEI film component of lithium hexafluorophosphate (electrolyte) in the electrolyte as closely as possible, thereby reducing the consumption of active lithium in the electrolyte. As a result, the positive electrode active material of this application can significantly improve the power performance and cycle life of the battery.

[0022] The battery module, battery pack, and power consumption device of this application include a lithium-ion battery according to this application, and therefore have at least the same advantages as the aforementioned lithium-ion battery. [Brief explanation of the drawing]

[0023] [Figure 1] This is a schematic diagram of the structure of the positive electrode active material of this application. [Figure 2] Figure A shows an SEM diagram of the positive electrode active material of one embodiment of this application, and Figure B shows an SEM diagram of the positive electrode active material of Comparative Example 1 of this application. [Figure 3] This is a schematic diagram of a lithium-ion battery according to one embodiment of the present application. [Figure 4] Figure 2 is an exploded view of a lithium-ion battery according to one embodiment of this application. [Figure 5] This is a schematic diagram of a battery module according to one embodiment of the present application. [Figure 6] This is a schematic diagram of a battery pack according to one embodiment of the present application. [Figure 7] Figure 5 is an exploded view of a battery pack according to one embodiment of this application. [Figure 8] This is a schematic diagram of a power consumption device according to one embodiment of the present application. [Modes for carrying out the invention]

[0024] The following describes in detail embodiments specifically disclosing the positive electrode active material and its manufacturing method, positive electrode plate, secondary battery, battery module, battery pack, and electrical device of this application, with appropriate reference to the drawings. However, unnecessary detailed explanations may be omitted. For example, detailed explanations of well-known matters and redundant explanations of structures that are actually the same may be omitted. This is to avoid making the following explanation unnecessarily long and to make it easily understandable to those skilled in the art. The drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and do not limit the topics described in the claims.

[0025] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, which define the boundary of a particular range. The range thus limited may or may not include the endpoints, and any combination is possible, that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 can also be assumed. Furthermore, if the minimum range values ​​are listed as 1 and 2, and the maximum range values ​​are listed as 3, 4 and 5, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 can all be assumed. In this application, unless otherwise specified, the numerical range “ab” represents an abbreviation for any combination of real numbers a to b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have already been listed in this specification, and "0-5" is simply an abbreviated representation of combinations of these numbers. Also, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that this parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0026] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical inventions.

[0027] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical concepts.

[0028] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the fact that the method includes steps (a) and (b) means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, the fact that the method referred to above may further include step (c) 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 steps (a), (c) and (b), or steps (c), (a) and (b), and so on.

[0029] Unless otherwise specified, the terms “includes” and “inclusion” as used in this application may be open or closed. For example, “includes” and “inclusion” may mean that other components not listed may be included or inclusion, or that only the listed components may be included or inclusion.

[0030] 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 conditions A is true (or exists) and B is false (or does not exist), the condition A is false (or does not exist) but B is true (or exists), and the condition both A and B are true (or exist) all satisfy "A or B."

[0031] It should be explained that the term "coating layer" refers to the portion that covers the surface of the substrate. This portion may completely cover the substrate, but it does not necessarily have to completely cover it. The use of "coating layer" is merely for the sake of clarity and is not intended to limit this application.

[0032] A series of positive electrode active materials for lithium-ion batteries, particularly nickel-cobalt-manganese ternary systems, have two unavoidable and disadvantageous drawbacks to their electrical performance: 1) a relatively high oxidation activity ratio, and 2) a slow solid-phase lithium ion transmission rate. The high oxidation activity causes the electrolyte to constantly oxidize and decompose on the positive electrode surface during the battery cycle, consuming the limited active lithium in the positive electrode. Decomposition products accumulate on the positive electrode surface, significantly increasing the diffusion resistance at the lithium ion interface, thereby degrading the battery's power performance and cycle life. Therefore, to overcome these drawbacks, the positive electrode active material needs to be modified.

[0033] The constant oxidative decomposition of the electrolyte on the positive electrode surface is actually a process in which components such as the solvent, electrolyte, and additives in the electrolyte are constantly decomposed on the positive electrode, forming a CEI (cathode electrolyte interface) film on the positive electrode surface. Therefore, if the positive electrode active material can be modified by coating it in situ to pre-form the CEI film active components, and if the CEI film can be formed in situ on the positive electrode active material surface using these pre-formed active components, the probability of the electrolyte being oxidized can be significantly reduced, and it will also prevent the consumption of active lithium and the accumulation of electrolyte decomposition by-products, thereby significantly improving the battery's power and cycle performance.

[0034] Some lithium salts simultaneously containing two elements of fluorine and phosphorus, for example, lithium difluorophosphate, are generally added to an electrolyte as an additive to improve battery cycle performance. However, lithium difluorophosphate is difficult to dissolve in the electrolyte and has a low utilization rate; meanwhile, after adding lithium difluorophosphate to the electrolyte, the conductivity of the electrolyte is low, and even an addition amount of 1% greatly deteriorates the conductivity, which is unfavorable for exerting the power performance of the battery.

[0035] Accordingly, the present application solves the above problems simultaneously and significantly improves the power and cycle performance of a lithium-ion battery by, for example, using the above lithium difluorophosphate-based lithium salt as a modifier for modifying a positive electrode active material.

[0036] [Positive Electrode Active Material] The present application provides a positive electrode active material, the positive electrode active material comprising a substrate and a coating layer located on a surface of the substrate, the substrate comprises a first lithium salt, and the first lithium salt is layered structure LiAO2, Li[Ni a Co b Mn c O2, and lithium-rich manganese-based xLi2MnO3·(1-x)LiMn y Z 1-y O2, wherein A is Ni, Co, Mn or Al, the above-mentioned Z is one or two metal ions selected from Ni, Co or Al, and 0.1≦x≦0.9, 0.1≦y≦0.9, 0<a<1, 0<b<1, 0<c<1, a+b+c=1. The coating layer comprises a second lithium salt simultaneously containing three elements of fluorine, phosphorus and oxygen, and the oxygen in the second lithium salt contains lone electron pairs.

[0037] By coating the surface of the first lithium salt of this application with a coating layer containing a second lithium salt, on the one hand, corrosion decomposition of the first lithium salt in the substrate by the electrolyte can be prevented, and the occurrence of side reactions can be reduced. On the other hand, the second lithium salt can form a CEI film in situ on the surface of the first lithium salt particles, thereby improving the film structure and increasing the transmission rate of lithium ions in the positive electrode active material. Furthermore, the second lithium salt contains both fluorine and phosphorus, and the resulting film component can be made to match as closely as possible to the CEI film component formed from lithium hexafluorophosphate (electrolyte) in the electrolyte, thereby reducing the consumption of active lithium in the electrolyte. In short, the positive electrode active material of this application can significantly improve the power performance and cycle life of the battery.

[0038] In some embodiments, the second lithium salt is at least one selected from lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0039] The structural formulas for lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate are as follows: [ka]

[0040] In the structural formula of the second lithium salt described above, in addition to being able to optimize the film structure by synthesizing a CEI film in situ on the surface of the first lithium salt, it also has an oxygen lone pair. The oxygen lone pair in the second lithium salt can adhere to the surface of the first lithium salt (referring to Figure 1.B, the surface of the untreated positive electrode active material particles in Figure 1 is smooth, and referring to Figure 1.A, the surface of the positive electrode active material of this application that has undergone modification treatment has a rough layer and deposited particles protruding from the surface of the rough layer) in the form of a uniform coating layer through complexation with lithium difluorophosphate and the transition metal ions in the first lithium salt. This not only prevents the coating layer from falling off the substrate, but also effectively prevents the leaching of the transition metal in the first lithium salt, and further prevents a decrease in battery performance.

[0041] Furthermore, the second lithium salt is selectively lithium tetrafluoro(oxalato)phosphate, and the second lithium salt with a higher fluorine atom content can increase the stability of the formed CEI film, which is even more beneficial for improving battery performance. Experiments have shown that, assuming all other conditions are the same, a cathode active material using lithium tetrafluoro(oxalato)phosphate as the second lithium salt can improve cycle performance by about 5% and reduce battery DCR by about 10%.

[0042] Furthermore, the surface of the coating layer of the positive electrode active material of this application has protruding deposited particles formed from the second lithium salt.

[0043] The coating layer of the positive electrode active material in this application consists of a layer with a relatively flat surface and protruding deposited particles located on the surface of the layer. In the layer with the relatively flat surface, the second lithium salt is uniformly distributed, further improving the microstructure of the CEI film on the surface of the positive electrode active material and improving the lithium ion transmission rate in the positive electrode active material. On the other hand, the protruding deposited particles consist of the second lithium salt, which is advantageous for replenishing the battery with additional lithium salt after long cycles and improving the amount of active lithium in the electrolyte, further improving the battery's lifespan.

[0044] In some embodiments, the mass percentage of the second lithium salt is 0.1% to 20% of the total mass of the positive electrode active material, and selectively 1% to 10%.

[0045] If the mass ratio of the second lithium salt at the positive electrode is less than 0.1%, an effective coating layer cannot be formed, and contact between the positive electrode active material and the electrolyte cannot be effectively inhibited. In other words, side reactions at the electrolyte-positive electrode interface cannot be effectively suppressed. If the mass ratio of the second lithium salt at the positive electrode is greater than 10%, the effect cannot be further improved, and instead, costs increase, and lithium ion transmission may be hindered.

[0046] In some embodiments, the thickness of the coating layer of the positive electrode active material is 10 to 100 nm, and selectively 20 to 60 nm.

[0047] By keeping the thickness of the coating layer within a reasonable range, it is possible not only to maintain the effectiveness of the second lithium salt but also to prevent the inhibition of lithium ion transmission, which would reduce power performance.

[0048] In some embodiments, the positive electrode active material consists of first particles with a volume-average particle size Dv50 of 2 to 8 μm and second particles with a volume-average particle size Dv50 of 13 to 22 μm.

[0049] In some embodiments, the positive electrode active material consists of a first particle and the second particle, and the mass ratio of the two is 2.3 to 9:1.

[0050] The adaptive combination of the first and second particles allows for a higher concentration of positive electrode active material per unit thickness of the positive electrode film layer, improving the material's compaction density and further enhancing the battery's energy density.

[0051] Furthermore, if the mass ratio of the first particle to the second particle is greater than 9:1, the material has a higher proportion of large particles, which can extend the path in solid-phase lithium ion transport and have a certain effect on the battery's power performance. If the mass ratio of large particles to small particles is less than 2.3:1, the positive electrode active material has a higher proportion of small particles, resulting in a relatively large specific surface area and uneven coating of the coating layer, which may affect the effectiveness of the second lithium salt.

[0052] The particle size of the cathode material can be achieved by conventional grinding processes. For example, a first particle size of 2-8 μm can be obtained using a mechanical grinder, and a second particle size of 13-22 μm can be obtained using an air-jet grinder.

[0053] In some embodiments, the first and / or second particles simultaneously include two crystalline forms: single crystal and polycrystalline.

[0054] In this application, single crystals have long ion transport paths but relatively low specific surface area and relatively few side reactions, while polycrystalline crystals have a specific surface area. product Although it has a large size and many side reactions, the lithium-ion transmission path is short and the power performance is relatively good, and by combining the two, it is possible to integrate the advantages of both.

[0055] This application provides a method for producing a positive electrode active material, and this method is Step S1 involves drying and dehydrating the first lithium salt to obtain the first lithium salt after drying, Step S2 involves dissolving the second lithium salt in an organic solvent to obtain an organic solution of the second lithium salt, Step S3 involves adding the dried first lithium salt to the second lithium salt organic solution and mixing them uniformly. Step S4 includes filtering a uniformly mixed mixture and heat-treating the filtered solid particles to obtain the positive electrode active material comprising a substrate and a coating layer located on the surface of the substrate. The substrate comprises a first lithium salt, the first lithium salt having a layered structure of LiAO2, Li[Nia Co b Mn c O2 and lithium-rich manganese-based xLi2MnO3·(1-x)LiMn y Z 1-y O2, wherein A is Ni, Co, Mn or Al, and the Z is one or two metal ions selected from Ni, Co or Al, and 0.1≦x≦0.9, 0.1≦y≦0.9, 0<a<1, 0<b<1, 0<c<1, a+b+c=1. The coating layer comprises a second lithium salt simultaneously containing fluorine and phosphorus.

[0056] In some embodiments, before step S1, the method further comprises step S0, wherein step S0 comprises producing a single-crystal first lithium salt and / or a polycrystalline first lithium salt.

[0057] In some embodiments, the method further comprises step S5, wherein step S5 comprises adjusting the volume-average particle diameter Dv50 of the positive electrode active material to obtain first particles having a volume-average particle diameter Dv50 of 2 to 8 µm and second particles having a volume-average particle diameter Dv50 of 13 to 22 µm.

[0058] In some embodiments, the method further comprises step S6, wherein step S6 comprises mixing the first particles and the second particles at a predetermined mass ratio to obtain the positive electrode active material.

[0059] In some embodiments, in step S1, the temperature range for drying and dehydrating the first lithium salt is 100 to 200°C.

[0060] In some embodiments, in step S2, the organic solvent is an ether-based, carboxylate-based or carbonate-based organic solvent.

[0061] In some embodiments, in step S3, the uniform mixing method is stirring and dispersing at 50 to 100°C for 4 to 8 hours, and / or In some embodiments, in step S4, the heat treatment method involves treating the material in an air atmosphere at 200-250°C for 5-10 hours.

[0062] [Positive electrode plate] This application provides a positive electrode plate, the positive electrode plate comprising the positive electrode active material of this application.

[0063] The positive electrode plate includes a positive electrode current collector and a positive electrode material placed on at least one surface of the positive electrode current collector. For example, the positive electrode current collector has two opposing surfaces in its thickness direction, and the positive electrode material is placed on one or both of the two opposing surfaces of the positive electrode current collector.

[0064] In the lithium-ion battery of this application, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. 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 base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), 1,3-propanesultone (PS), or polyethylene (PE)), but this application is not limited to these materials.

[0065] The cathode material may further selectively include a conductive agent. The type of conductive agent is not specifically limited, and those skilled in the art can select one according to their actual needs. For example, the conductive agent used in the cathode material may be selected from one or more of the following: superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0066] In this application, a positive electrode plate can be manufactured by methods known in the art. For example, the positive electrode active material, conductive agent, and adhesive of this application may be dispersed in a solvent (e.g., N-methylpyrrolidone (NMP)) to form a uniform positive electrode slurry, the positive electrode slurry may be coated onto a positive electrode current collector, and after processes such as drying and cold pressing, a positive electrode plate may be obtained.

[0067] [Negative electrode plate] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer placed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0068] For example, the negative electrode current collector has two opposing surfaces in its thickness direction, and the negative electrode film layer is placed on one or both of the two opposing surfaces of the negative electrode current collector.

[0069] In the lithium-ion battery of this application, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, copper foil may be used as the metal foil sheet. 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 base layer. The composite current collector may be formed by forming a metal material (such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)), but this application is not limited to these materials.

[0070] In the negative electrode plate of this application, the negative electrode film layer generally contains a negative electrode active material, a selective adhesive, a selective conductive agent, and other selective auxiliary agents, and is generally obtained by coating it with a negative electrode slurry and drying it. The negative electrode slurry is generally formed by dispersing the negative electrode active material, a selective conductive agent, an adhesive, etc., in a solvent and stirring it uniformly. The solvent may be N-methylpyrrolidone (NMP) or deionized water.

[0071] For example, the conductive agent may be selected from one or more of the following: superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0072] In the negative electrode plate of this application, the negative electrode film layer further selectively contains other commonly used negative electrode active materials in addition to the negative electrode active material. Examples of other commonly used negative electrode active materials include artificial graphite, natural graphite, soft carbon, hard carbon, silicone-based materials, tin-based materials, and lithium titanate. The silicone-based material may be selected from one or more of elemental silicone, silicone oxide, silicone-carbon composite, silicone-nitrogen composite, and silicone alloy. The tin-based material may be selected from one or more of elemental tin, tin oxide, and tin alloy.

[0073] [Electrolyte] The electrolyte plays the role of conducting ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and it can be selected according to the needs. For example, the electrolyte may be selected from at least one of a solid electrolyte and a liquid electrolyte (i.e., an electrolyte solution).

[0074] In some embodiments, an electrolyte solution is used as the electrolyte. The electrolyte solution comprises an electrolyte salt and a solvent.

[0075] In some embodiments, the electrolyte salt may be selected from one or more of the following: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0076] In some embodiments, the solvent may be selected from one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0077] In some embodiments, the electrolyte further selectively includes additives. For example, the additives may include a negative electrode film forming additive, a positive electrode film forming additive, and further additives that can improve some of the battery's performance characteristics, such as additives that improve the battery's overcharge performance, additives that improve the battery's high-temperature performance, and additives that improve the battery's low-temperature performance.

[0078] [Separator] Lithium-ion batteries employing an electrolyte, and lithium-ion batteries employing some solid electrolytes, further include a separator. The separator is placed between the positive electrode plate and the negative electrode plate and performs a separating function. This application does not particularly limit the type of separator, and any known porous structure separator with good chemical and mechanical stability may be selected. In some embodiments, the material of the separator may be selected from one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and is not particularly limited.

[0079] [Lithium-ion battery] In some embodiments, the positive electrode plate, negative electrode plate and separator may be manufactured into an electrode assembly by a winding process or a lamination process, and the positive electrode plate may be the lithium iron phosphate positive electrode active material of this application.

[0080] In some embodiments, the lithium-ion battery may include an outer casing. This casing may be used to package the electrode assembly and electrolyte.

[0081] In some embodiments, the outer casing of the lithium-ion battery may be a rigid case, such as a rigid plastic case, an aluminum case, or a steel case. The outer casing of the lithium-ion battery may also be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, and examples of plastics include polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0082] This application does not particularly limit the shape of the lithium-ion battery, which may be cylindrical, rectangular, or any other shape. For example, Figure 2 shows a rectangular lithium-ion battery 5 as an example.

[0083] In some embodiments, referring to Figure 3, the exterior may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates enclosing and forming a housing cavity. The case 51 has an opening that communicates with the housing cavity, and the cover plate 53 can cover the opening so as to seal the housing cavity. The positive electrode plate, negative electrode plate and separator can be formed into an electrode assembly 52 by a winding process or a lamination process. The electrode assembly 52 is packaged within the housing cavity. The electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the lithium-ion battery 5 may be one or more, and those skilled in the art can select according to their specific needs.

[0084] [Battery Module] In some embodiments, the lithium-ion batteries may be assembled into a battery module, and the number of lithium-ion batteries included in the battery module may be one or more, and the specific number can be selected by those skilled in the art depending on the application and capacity of the battery module.

[0085] Figure 4 shows an example of a battery module 4. Referring to Figure 4, in the battery module 4, the multiple lithium-ion batteries 5 may be arranged sequentially along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, these multiple lithium-ion batteries 5 may be fixed in place with fasteners.

[0086] Selectively, the battery module 4 may further include a housing having a housing space, in which a plurality of lithium-ion batteries 5 are housed.

[0087] [Battery pack] In some embodiments, the battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0088] Figures 5 and 6 show an example of a battery pack 1. Referring to Figures 5 and 6, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, the upper housing 2 covering the lower housing 3 and forming a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0089] [Power consumption equipment] Furthermore, this application provides a power consumption device comprising one or more of the lithium-ion battery, battery module, or battery pack according to this application. The lithium-ion battery, battery module, or battery pack may be used as a power source for the device or as an energy storage unit for the device. The device may be, 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.

[0090] As the power consumption device, a lithium-ion battery, battery module, or battery pack can be selected according to the usage demand.

[0091] Figure 7 shows an example of a device. This device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the demand for high power output and high energy density of lithium-ion batteries in this device, a battery pack or battery module can be employed.

[0092] Other examples of such devices may include mobile phones, tablet computers, and laptop computers. These devices generally require a thin profile and can utilize lithium-ion batteries as their power source.

[0093] Examples Examples of the present application are described below. The examples described below are illustrative and are used only for interpreting this application and should not be understood as limitations thereon. Unless specific techniques or conditions are specified in the examples, they shall be carried out in accordance with the techniques or conditions described in the literature in the art or in accordance with the product specifications. Unless the manufacturer is specified, the reagents or equipment used are all common products that are readily available on the market and commonly used in the art. Unless otherwise specified, the content of each component in the examples of this application is calculated on a mass basis.

[0094] Examples Example 1 [Manufacturing of positive electrode active material] S0: The first lithium salt in single-crystal / polycrystalline form, LiNi 0.8 Co 0.1 Mn 0.1 O2 production S01): Single-crystal LiNi 0.8 Co 0.1 Mn 0.1 O2 production Precursor Ni 0.8 Co 0.1 Mn 0.1 (OH)2 and lithium carbonate are added to a mortar and pestle, and ground continuously for 10-15 minutes until uniformly mixed. Here, the molar ratio of Li to the sum of the transition metals is 1.2-1.25. Then, it is placed in a tubular furnace, the air is first exhausted with nitrogen gas, then oxygen gas is introduced and the temperature is raised to 820-900°C, followed by firing for 12 hours. The initial heating rate is 10°C / min, and the final cooling rate is 10°C / min. After cooling, it is ground in a mortar and pestle and passed through a sieve to obtain single crystal LiNi 0.8 Co 0.1 Mn 0.1 O2 was obtained.

[0095] S02): Precursor 0.8 Co 0.1 Mn 0.1 (OH)2 and lithium carbonate are added to a mortar and pestle, and ground continuously for 10-15 minutes until uniformly mixed. Here, the molar ratio of Li to the sum of the transition metals is 1.0-1.15. Then, it is placed in a tubular furnace, the air is first exhausted with nitrogen gas, then oxygen gas is introduced and the temperature is raised to 600-800°C, followed by firing for 12 hours. The initial heating rate is 10°C / min, and the final cooling rate is 10°C / min. After cooling, it is ground in a mortar and pestle and passed through a sieve to obtain polycrystalline LiNi 0.8 Co 0.1 Mn 0.1 O2 was obtained.

[0096] S1: Single crystal form of LiNi 0.8 Co 0.1 Mn 0.1 O2 and polycrystalline LiNi 0.8 Co 0.1 Mn 0.1 O2 was uniformly mixed with the solution in a mass ratio of 0.4:1, and the mixture was dried and dehydrated at 150°C for 2 hours to obtain the first lithium salt after drying. S2: Dissolve the second lithium salt, lithium difluorophosphate, in 1,2-dimethoxyethane. 、 The mass fraction of lithium difluorophosphate is set to 15%. S3: The dried first lithium salt is added to the 1,2-dimethoxyethane solution of the second lithium salt, the amount of the first lithium salt added being 90% of the sum of the masses of the first and second lithium salts, and the mixture is dispersed by stirring at 30°C for 4 hours. S4: The above uniformly mixed mixture is filtered, and the filtered solid particles are treated in an air atmosphere at 200°C for 5 hours to obtain a positive electrode active material in which single-crystal and polycrystalline forms are mixed. S5: Manufacturing of the first / second particle The positive electrode active material obtained in step S4 is pulverized with a mechanical pulverizer of a specific frequency to obtain first particles with a particle size of 5 μm, and the positive electrode active material obtained in step S4 is pulverized with an air-jet pulverizer of a specific frequency to obtain second particles with a particle size of 15 μm. S6: The first and second particles were mixed in a mass ratio of 3:1 to obtain the positive electrode active material of Example 1.

[0097] [Positive electrode plate] In Example 1, the positive electrode active material, conductive agent Super P, and adhesive polyvinylidene fluoride (PVDF) were prepared as a positive electrode slurry in N-methylpyrrolidone (NMP). The solid content of the positive electrode slurry was 50 wt%, and the mass ratio of the positive electrode active material, Super P, and PVDF in the solid content was 8:1:1. The positive electrode slurry was applied to the aluminum foil current collector and dried at 85°C, then cold-pressed, trimmed, cut, and slit, and then dried for 4 hours under vacuum conditions at 85°C to produce the positive electrode slurry. very They manufactured the boards.

[0098] [Negative electrode plate] A negative electrode slurry was prepared by uniformly mixing graphite, a conductive agent Super P, a thickening agent CMC, and an adhesive styrene-butadiene rubber (SBR) in deionized water. The solid content of the negative electrode slurry was 30 wt%, and the mass ratio of graphite, Super P, CMC, and the adhesive styrene-butadiene rubber (SBR) in the solid content was 80:15:3:2. The negative electrode slurry was applied to a copper foil current collector and dried at 85°C. After cold pressing, trimming, cutting, and slitting, the negative electrode plate was dried for 12 hours under vacuum conditions at 120°C to produce the negative electrode plate.

[0099] [Electrolyte] EC:DEC:DMC are mixed in a volume ratio of 1:1:1, and LiPF6 is added to form an electrolyte, in which the concentration of LiPF6 in the electrolyte is 1 mol / L.

[0100] [Separator] Polyethylene separator.

[0101] [Manufacturing of lithium-ion batteries] The positive electrode plate, separator, and negative electrode plate were stacked in order so that the separator was positioned between the positive and negative electrode plates to act as a separator. After being wound up as a rectangular bare cell, an aluminum plastic film was loaded, the appropriate non-aqueous electrolyte was injected, the cell was sealed, and after going through processes such as standing, hot and cold pressing, chemical conversion, jigs, and volume division, a lithium-ion battery was obtained.

[0102] Comparative Example 1 Regularly available Lithium 0.8 Co 0.1 Mn 0.1 O2 was used, the product model number was (HAH101, purchased from Hunan Bangpu Circulation Technology Co., Ltd.), and the other manufacturing processes were the same as in Example 1. Example 2 In the [Production of Cathode Active Material], in step S1, the first lithium salt used is LiNiO2, and the second lithium salt used is lithium difluorobis(oxalato)phosphate. In step S3, the amount of the first lithium salt added is 91% of the sum of the masses of the first and second lithium salts. In step S5, the particle size of the first particles is manufactured to 7 μm, and the particle size of the second particles is manufactured to 16 μm. The other manufacturing processes are the same as in Example 1.

[0103] Example 3 In the [manufacturing of positive electrode active material], in step S1, the first lithium salt used is LiMnO2, and the second lithium salt used is lithium tetrafluoro(oxalato)phosphate. In step S3, the amount of the first lithium salt added is 91% of the sum of the masses of the first and second lithium salts. In step S6, the mixing mass ratio of the first particles to the second particles is 4:1. The other manufacturing processes are the same as in Example 1.

[0104] Example 4 In the [manufacturing of positive electrode active material], in step S1, the first lithium salt used is 0.5Li2MnO3·0.5LiMn 0.3 Co 0.7 The oxygen is O2, and the other manufacturing processes are the same as in Example 1.

[0105] Examples 5 to 15 In the [manufacturing of positive electrode active material], in step S1 and step S3, the amount of the first lithium salt added is 1.8%, 5%, 15%, 20%, 0.9%, 30%, 0.10%, 5%, 20%, 0.01%, and 25% of the sum of the masses of the first lithium salt and the second lithium salt, respectively, and the other manufacturing processes are the same as in Example 1.

[0106] Examples 16-20 In the [manufacturing of positive electrode active material], in step S5, the particle sizes of the first particles are manufactured to 2 μm, 4 μm, 8 μm, 1 μm, and 10 μm, respectively, and the other manufacturing processes are the same as in Example 1.

[0107] Examples 21-25 In the [manufacturing of positive electrode active material], in step S5, the particle sizes of the second particles are manufactured to 13 μm, 18 μm, 22 μm, 10 μm, and 25 μm, respectively, while the other manufacturing processes are the same as in Example 1.

[0108] Examples 26-30 In the [manufacturing of positive electrode active material], in step S6, the mixed mass ratios of the first particles and the second particles are 2.3:1, 4:1, 9:1, 1.8:1, and 9.5:1, respectively, and the other manufacturing processes are the same as in Example 1.

[0109] Example 31 In the [Production of Cathode Active Material], step S0 does not include step S02, which is for producing the polycrystalline first lithium salt, and the other processes are similar to those in Example 1.

[0110] [Parameter testing related to positive electrode active material] 1. Detection of the second lithium salt component and its mass ratio in the positive electrode active material (using lithium difluorophosphate as an example) The content of the second lithium salt was tested according to the general rules for ion chromatography analysis in JY / T 020-1996.

[0111] 2. Volume-average particle size Dv50 test Refer to GB / T19077-2016 D v 50 tests were conducted.

[0112] 3. Coating layer thickness test An IB-19500CP ion polishing apparatus was used. After cleaning the sample preparation tools, the sample preparation adhesive (a gel-like substance formed by dispersing PVDF in NMP, with a PVDF mass content of 8%) and the sample powder (the powder weight is approximately 5 times that of the adhesive) were uniformly mixed and then applied to copper foil and dried at 60°C for 30 minutes. The prepared samples were cut to a size of 6 mm x 6 mm with scissors, fixed to the sample stage, and cut in the ion polishing apparatus (model number: IB-19500CP). The samples cut according to JBT9352-1999 were subjected to thickness testing using a US FEI Tecnai G2 transmission electron microscope.

[0113] [Battery performance test] 1, initial discharge capacity At 25°C, a lithium-ion battery is charged with a constant current of 1C to 4.25V, then charged with a constant voltage until the current reaches 0.05C. After the battery is fully charged, it is left to stand for 5 minutes, discharged at 1C for 30 minutes (the battery's state of charge is 50%), left to stand for 5 minutes, the temperature is adjusted to 25°C, and it is left to stand for 1 hour. The battery voltage V1 at this time is recorded, and the battery is discharged at 0.4C for 15 seconds. The voltage V2 after pulse discharge is recorded, and the DCR at 50% SOC is (V1-V2) / I, so I = 0.4C.

[0114] 2. Cycle capacity maintenance rate Charge and discharge tests were performed on all lithium-ion batteries of the examples and comparative examples at 25°C. One charge and discharge cycle process was as follows: constant current charging at 1C up to 4.25V, then constant voltage charging at 4.25V down to a current of ≤0.05mA, left to stand for 5 minutes, and then constant current discharge at 1C up to 2.8V. The battery capacity at this time was recorded as C1. This constitutes one charge and discharge cycle of the battery. The above process was repeated 200 times, and the battery capacity at this time was recorded as C200. Then, the cycle capacity retention rate = C200 / C1 × 100%.

[0115] For the product parameters of the positive electrode active material and lithium-ion battery performance parameters of the examples and comparative examples, please refer to Tables 1 to 6.

[0116] [Table 1]

[0117] As can be seen from Table 1, Example 1 and Comparative Example 1 show that the unmodified positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 Compared to O2, the power performance and cycle life of lithium-ion batteries were significantly improved. Examples 2-4 demonstrate that lithium-ion batteries exhibit superior power performance and cycle life when coated with different types of second lithium salts described in this application for different first lithium salts.

[0118] [Table 2]

[0119] As can be seen from Table 2, the power performance and cycle life of the lithium-ion batteries corresponding to Examples 1 and 5-9 were superior to those of Examples 9 and 10. The coating layer thickness was in the range of 10-100 nm, which is a preferred range, and the performance was even better when the coating layer thickness was in the range of 20-60 nm.

[0120] [Table 3]

[0121] As can be seen from Table 3, the power performance and cycle life of the lithium-ion batteries corresponding to Examples 1 and 11-14 are superior to those of Examples 14 and 15. This indicates that a mass percentage of the second lithium salt of 0.1% to 20% is a preferred range, and performance is even better when the mass percentage of the second lithium salt is 1% to 10%.

[0122] [Table 4]

[0123] As can be seen from Table 4, the power performance and cycle life of the lithium-ion batteries corresponding to Examples 1 and 16-24 were superior to those of Examples 24 and 25, and it was shown that the performance was better when the positive electrode active material consisted of first particles with a volume-average particle size Dv50 of 2-8 μm and second particles with a volume-average particle size Dv50 of 13-22 μm.

[0124] [Table 5]

[0125] As can be seen from Table 5, the power performance and cycle life of the lithium-ion batteries corresponding to Examples 1 and 26-29 were superior to those of Examples 29 and 30, and it was shown that the performance was superior when the mass ratio of the first particle to the second particle was in the range of 2.3 to 9:1.

[0126] [Table 6]

[0127] As can be seen from Table 6, when the first and second particles contain both single-crystal and polycrystalline forms, the power performance of the lithium-ion battery was further improved.

[0128] It should be noted that this application is not limited to the embodiments described above. The embodiments described above are merely examples, and any embodiments that have substantially the same configuration as the technical idea and produce the same effects within the scope of the technical proposal of this application are included within the scope of the technical proposal. Furthermore, other methods that are constructed by adding various modifications to the embodiments that a person skilled in the art could conceive, and by combining some of the components of the embodiments, are also included within the scope of this application, without departing from the spirit of this application. [Explanation of Symbols]

[0129] 1 battery pack, 2 upper casing, 3 Lower casing, 4 battery modules, 5 Lithium-ion batteries, 51 cases, 52 electrode assembly, 5 3 months bar plate .

Claims

1. It is a positive electrode active material, It comprises a substrate and a coating layer located on the surface of the substrate, The base body contains a first lithium salt, and the first lithium salt is LiAO having a layered structure ２ , Li[Ni ａ Co ｂ Mn ｃ O ２ and lithium-rich manganese-based xLi ２ MnO ３ ·(1-x)LiMn ｙ Z １－ｙ O ２ is at least one selected from the group consisting of, wherein A is Ni, Co, Mn or Al, Z is one or two metal ions selected from Ni, Co or Al, and 0.1≦x≦0.9, 0.1≦y≦0.9, 0<a<1, 0<b<1, 0<c<1, a+b+c=1, The coating layer contains a second lithium salt that simultaneously contains fluorine, phosphorus, and oxygen, and the second lithium salt is at least one selected from lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate. The positive electrode active material consists of first particles with a volume-average particle size Dv50 of 2 to 8 μm and second particles with a volume-average particle size Dv50 of 13 to 22 μm. With respect to the total mass of the positive electrode active material, the mass ratio of the second lithium salt is 0.1% to 20%. The thickness of the coating layer is 10 to 100 nm. The mass ratio of the first particle to the second particle is 2.3 to 9:

1. The first and / or second particles include two crystalline forms, single crystal and polycrystalline, and the mass ratio of single crystal particles to polycrystalline particles is 0.1 to 1:

1. A positive electrode active material characterized by the following features.

2. The positive electrode active material according to claim 1, characterized in that the surface of the coating layer has protruding deposited particles formed from the second lithium salt.

3. A method for producing a positive electrode active material, Step S1 involves drying and dehydrating the first lithium salt to obtain the dried first lithium salt, Step S2 involves dissolving the second lithium salt in an organic solvent to obtain an organic solution of the second lithium salt, Step S3 involves adding the dried first lithium salt to the second lithium salt organic solution and mixing them uniformly. Step S4 involves filtering the uniformly mixed mixture and then heat-treating the solid particles after filtering. Step S5 includes adjusting the volume-average particle size Dv50 of the material obtained in step S4 to obtain first particles with a volume-average particle size Dv50 of 2 to 8 μm and second particles with a volume-average particle size Dv50 of 13 to 22 μm, thereby obtaining the positive electrode active material. The positive electrode active material comprises a substrate and a coating layer located on the surface of the substrate. The substrate comprises a first lithium salt, the first lithium salt having a layered structure of LiAO ２ , Li[Ni ａ Co ｂ Mn ｃ ]O ２ , and lithium-rich manganese xLi ２ MnO ３ ・(1-x)LiMn ｙ Z １－ｙ O ２ At least one selected from, where A is Ni, Co, Mn or Al, and Z is one or two metal ions selected from Ni, Co or Al, and 0.1 ≤ x ≤ 0.9, 0.1 ≤ y ≤ 0.9, 0 < a < 1, 0 < b < 1, 0 < c < 1, a + b + c = 1, and the coating layer comprises a second lithium salt containing both fluorine and phosphorus, and the second lithium salt is at least one selected from lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate. With respect to the total mass of the positive electrode active material, the mass ratio of the second lithium salt is 0.1% to 20%. The thickness of the coating layer is 10 to 100 nm. The mass ratio of the first particle to the second particle is 2.3 to 9:

1. The first and / or second particles include two crystalline forms, single crystal and polycrystalline, and the mass ratio of single crystal particles to polycrystalline particles is 0.1 to 1:

1. A method for producing a positive electrode active material, characterized by the above.

4. The manufacturing method according to claim 3, further comprising step S0 prior to step S1, wherein step S0 includes the step of producing a first lithium salt in single crystalline form and / or a first lithium salt in polycrystalline form.

5. The manufacturing method according to claim 3, further comprising step S6, wherein step S6 includes mixing the first particles and the second particles in a predetermined mass ratio to obtain the positive electrode active material.

6. In S1, the temperature range for drying and dehydrating the first lithium salt is 100-200°C. In S2 above, the organic solvent is an ether-based, carboxylic acid ester-based, or carbonate-based organic solvent. In S3, the method for uniform mixing is to disperse by stirring at 50 to 100°C for 4 to 8 hours. The manufacturing method according to claim 3 or 4, characterized in that, in S4, the heat treatment method is to treat in an air atmosphere at 200 to 250°C for 5 to 10 hours.

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