Phosphate positive electrode material precursor and preparation method thereof, positive electrode active material, battery monomer, battery and electric device

Abstract

The invention provides a phosphate positive electrode material precursor and a preparation method thereof, a positive electrode active material, a battery monomer, a battery and an electric device, and belongs to the technical field of lithium batteries. According to the preparation method of the phosphate positive electrode material precursor, the carbon source is added into the precursor reaction solution, and the carbon source can be uniformly distributed on the surfaces of manganese ions and / or ferrous ions to form a layer of film, so that a conductive network is formed, and carbon can be uniformly distributed on the surfaces of compound crystal grains; and the precursor can also be embedded into compound crystal grains for in-situ doping and coating, so that the conductivity and gram volume of a positive electrode active material prepared from the phosphate positive electrode material precursor are improved. Meanwhile, the carbon source can also play a role of a dispersing agent in the reaction solution, so that ions in the reaction solution are uniformly dispersed in the preparation process of the phosphate positive electrode material precursor, the reaction is more sufficient, and the structural stability of the prepared positive electrode active material is improved.

Description

Technical Field

[0001] This application relates to the field of lithium battery technology, specifically to a phosphate-based cathode material precursor and its preparation method, cathode active material, battery cell, battery, and power device. Background Technology

[0002] In recent years, with the increasingly widespread application of lithium-ion batteries, they have been widely used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and many other fields. Phosphate-based cathode materials, due to their stable olivine structure, outperform traditional lithium-ion battery cathode materials in terms of cycle performance and safety. Furthermore, their synthesis requires abundant resources, resulting in a significant cost advantage, and thus they have been widely adopted.

[0003] However, phosphate-based cathode materials have poor conductivity and low specific capacity, which cannot meet the electrical performance requirements of lithium-ion batteries, thus restricting their widespread application. Summary of the Invention

[0004] This application is made in view of the above-mentioned issues, and its purpose is to provide a phosphate-based cathode material precursor and its preparation method, cathode active material, battery cell, battery and power device, which can improve the conductivity and specific capacity of the cathode active material.

[0005] To achieve the above objectives, a first aspect of this application provides a phosphate-based cathode material precursor, comprising a compound and a carbon source layer, wherein the carbon source layer is distributed within the grains formed by the compound and coats the surface of the grains formed by the compound; the compound contains iron and / or manganese.

[0006] Therefore, the carbon source layer of the phosphate-based cathode material precursor of this application is embedded in the interior and surface of the grain, which can improve the conductivity and specific capacity of the cathode active material obtained from the phosphate-based cathode material precursor.

[0007] In any embodiment, the molar ratio of manganese to iron in the compound is 6:4 to 7:3. By making the molar ratio of manganese to iron in the compound 6:4 to 7:3, the prepared positive electrode active material has a high specific capacity, and the prepared battery has good cycle performance.

[0008] In any embodiment, the anion of the compound includes phosphate, carbonate, or oxalate. By including phosphate, carbonate, or oxalate as the anion of the compound, the resulting positive electrode active material contains fewer impurities.

[0009] In any embodiment, the carbon source includes organic carbon sources and / or inorganic carbon sources. When the carbon source includes organic carbon sources and / or inorganic carbon sources, the carbon sources can be uniformly distributed on the surface of manganese ions and / or ferrous ions to form a thin film, constituting a conductive network. This allows carbon to not only be uniformly distributed on the surface of the compound grains but also to be embedded inside the compound grains for in-situ doping and coating, thereby improving the conductivity and specific capacity of the positive electrode active material obtained from the phosphate-based positive electrode material precursor.

[0010] In any embodiment, the organic carbon source includes any one or more of glucose, starch, sucrose, fructose, cellulose, citric acid, and ascorbic acid; and / or, the inorganic carbon source includes any one or more of conductive carbon, graphene, conductive carbon fiber, and carbon nanotubes. All of the above carbon sources can be uniformly distributed on the surface of manganese ions and / or ferrous ions to form a thin film, constituting a conductive network. This allows carbon not only to be uniformly distributed on the surface of the compound grains but also to be embedded within the compound grains for in-situ doping and coating, thereby improving the conductivity and specific capacity of the positive electrode active material obtained from phosphate-based positive electrode material precursors.

[0011] In any embodiment, the carbon source includes any one or more of ascorbic acid, citric acid, and carbon nanotubes. By selecting the above-mentioned carbon source, the conductivity and specific capacity of the positive electrode active material obtained from the phosphate-based positive electrode material precursor can be further improved.

[0012] The second aspect of this application provides a method for preparing a phosphate-based cathode material precursor, which includes mixing a compound precursor and an acid solution for preliminary crystallization to obtain a first mixture, mixing the first mixture and an alkaline solution to obtain a second mixture and subjecting it to an aging reaction, adding a carbon source to the second mixture during the aging reaction, and obtaining a precursor suspension after the aging reaction is completed; the compound precursor includes manganese and / or iron.

[0013] Therefore, the method for preparing the phosphate-based cathode material precursor of this application adds a carbon source to the precursor reaction solution, so that carbon can not only be uniformly distributed on the surface of the compound grains, but also be embedded in the interior of the compound grains for in-situ doping and coating, thereby improving the conductivity and specific capacity of the cathode active material obtained from the phosphate-based cathode material precursor.

[0014] In any embodiment, the mass of the carbon source accounts for 0.5% to 10% of the mass of the compound precursor. The carbon source layer in the phosphate-based cathode material precursor can act as a steric hindrance. By ensuring that the mass ratio of the carbon source to the mass of the compound precursor is within the above range, the particle size of the phosphate-based cathode material precursor can be controlled, thereby preventing excessive grain growth during the synthesis of the cathode active material, controlling the specific surface area of ​​the cathode active material, improving the overall uniformity of grain development, and improving the high-temperature performance of the obtained cathode active material.

[0015] In any embodiment, the molar ratio of total metal elements in the compound precursor to solute in the acid solution is 1:(0.6 to 1.3). By keeping the molar ratio of total metal elements in the compound precursor to solute in the acid solution within the above range, the compound precursor and the acid solution can undergo a preliminary crystallization reaction.

[0016] In any embodiment, stirring is maintained during the mixing of the compound precursor and the acid solution at a stirring rate of 10 rpm / min to 100 rpm / min. By maintaining the above stirring rate during the mixing of the compound precursor and the acid solution, the compound precursor and the acid solution can be mixed uniformly, thereby forming a homogeneous phase during the initial crystallization process.

[0017] In any embodiment, the pH value of the second mixture is 3 to 10. By keeping the pH value of the second mixture within the above range, it is beneficial for the grains in the second mixture to grow and develop again during the aging reaction, while simultaneously performing carbon doping and coating, so that carbon is fully incorporated into the interior of the grains and coated on the surface of the grains.

[0018] In any embodiment, the aging reaction time is 0.5 h to 10 h. By keeping the aging reaction time within the above range, it is beneficial for the grains in the second mixture to grow and develop again during the aging reaction, thereby obtaining a phosphate-based cathode material precursor with a suitable particle size.

[0019] In any embodiment, stirring is maintained during the mixing and aging reaction of the first mixture and the alkaline solution, with a stirring rate of 1 rpm / min to 50 rpm / min. By maintaining the above stirring rate during the mixing and aging reaction of the first mixture and the alkaline solution, the first mixture, the alkaline solution, and the carbon source can be mixed uniformly, and excessive grain growth of the phosphate-based cathode material precursor can be prevented, thereby controlling the particle size of the phosphate-based cathode material precursor.

[0020] In any embodiment, after obtaining the precursor suspension, the precursor suspension is filtered and washed to obtain a wet precursor material. The wet precursor material is then dried at 90℃~250℃ for 3h~10h to obtain a phosphate-based cathode material precursor. By sequentially filtering, washing, and low-temperature drying the precursor suspension, a phosphate-based cathode material precursor can be obtained. Low-temperature drying reduces carbon volatilization and avoids carbon phase transition, resulting in high residual carbon content and low energy consumption, allowing the carbon source layer to remain within the grains and preventing it from easily detaching.

[0021] A third aspect of this application also provides a positive electrode active material, the raw materials of which include the phosphate-based positive electrode material precursor of the above embodiments or the phosphate-based positive electrode material precursor prepared according to the preparation method of the phosphate-based positive electrode material precursor of the above embodiments.

[0022] Therefore, the positive electrode active material of this application has high conductivity and specific capacity.

[0023] A fourth aspect of this application also provides a battery cell including a positive electrode sheet, wherein the positive electrode sheet includes the positive electrode active material described in the above embodiments.

[0024] A fifth aspect of this application also provides a battery, including the battery cell described in the above embodiments.

[0025] A sixth aspect of this application also provides an electrical device including the battery described in the above embodiments.

[0026] This application provides a phosphate-based cathode material precursor and its preparation method. By adding a carbon source to the precursor reaction solution, the carbon source can be uniformly distributed on the surface of manganese ions and / or ferrous ions to form a thin film, constituting a conductive network. This allows carbon to not only be uniformly distributed on the surface of the compound grains but also to be embedded inside the compound grains for in-situ doping and coating, thereby improving the conductivity and specific capacity of the cathode active material obtained from the phosphate-based cathode material precursor. Simultaneously, the carbon source also acts as a dispersant in the reaction solution, ensuring uniform dispersion of ions during the preparation of the phosphate-based cathode material precursor, resulting in a more complete reaction and improved structural stability of the obtained cathode active material. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a secondary battery according to one embodiment of this application.

[0028] Figure 2 for Figure 1 An exploded view of a secondary battery according to one embodiment of this application is shown.

[0029] Figure 3 This is a schematic diagram of a battery module according to one embodiment of this application.

[0030] Figure 4 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0031] Figure 5 for Figure 1 An exploded view of a battery pack according to one embodiment of this application is shown.

[0032] Figure 6 This is a schematic diagram of an electrical device that uses a secondary battery as a power source according to one embodiment of this application.

[0033] Figure 7 This is an EDS layered diagram of the cathode material precursor of Embodiment 1 of this application.

[0034] Figure 8 This is a distribution diagram of C element in the cathode material precursor of Example 1 of this application.

[0035] Figure 9 This is a distribution diagram of Fe element in the cathode material precursor of Example 1 of this application.

[0036] Figure 10 This is a distribution diagram of Mn element in the cathode material precursor of Example 1 of this application.

[0037] Figure 11 This is a distribution diagram of the O element in the cathode material precursor of Example 1 of this application.

[0038] Figure 12 This is a scanning electron microscope image of the lithium manganese iron phosphate cathode material prepared in Example 1 of this application.

[0039] Figure 13 This is a scanning electron microscope image of the lithium manganese iron phosphate cathode material prepared in Comparative Example 1 of this application.

[0040] Explanation of reference numerals in the attached figures:

[0041] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Secondary battery; 51 Housing; 52 Electrode assembly; 53 Top cover assembly. Detailed Implementation

[0042] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the sintering method for the cathode material of this application. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of essentially 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 to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0043] 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.

[0044] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

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

[0046] 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.

[0047] To improve the conductivity of phosphate-based cathode materials, carbon coating is often used. However, this coating method cannot allow carbon to penetrate into the material, and carbon cannot be coated on some interfaces, which makes it impossible to effectively improve the conductivity of phosphate-based cathode materials.

[0048] Based on this, this application proposes a sintering method for cathode materials, and the following provides a more detailed description of this application and its optional embodiments.

[0049] This application provides a phosphate-based cathode material precursor, which includes a compound and a carbon source layer. The carbon source layer is distributed inside the grains formed by the compound and coats the surface of the grains formed by the compound. The compound contains iron and / or manganese.

[0050] The compound is a raw material containing iron and / or manganese elements for preparing phosphate-based cathode materials.

[0051] The carbon source layer is a layered structure formed by the carbon source that is embedded inside the grain and covers the surface of the grain.

[0052] It should be noted that the carbon source layer will be transformed into a carbon layer during the sintering process of preparing phosphate-based cathode materials from phosphate-based cathode material precursors.

[0053] As an example, a compound may contain only iron, only manganese, or both iron and manganese.

[0054] It should be noted that when the compound contains only iron, the precursor of the phosphate-based cathode material is the lithium iron phosphate cathode material precursor; when the compound contains only manganese, the precursor of the phosphate-based cathode material is the lithium manganese phosphate cathode material precursor; when the compound contains both iron and manganese, the precursor of the phosphate-based cathode material is the lithium manganese iron phosphate cathode material precursor, and the molar ratio of manganese and iron in the compound can be any ratio.

[0055] The carbon source layer of the phosphate-based cathode material precursor of this application is embedded inside the grain and on the grain surface, which can improve the conductivity and specific capacity of the cathode active material obtained from the phosphate-based cathode material precursor.

[0056] In some embodiments, the molar ratio of manganese to iron in the compound is 6:4 to 7:3.

[0057] As an example, the molar ratio of manganese to iron in a compound can be 6:4, 6.2:3.8, 6.5:3.5, 6.8:3.2, or 7:3.

[0058] Optionally, the molar ratio of manganese to iron in the compound is 6:4 or 7:3.

[0059] By adjusting the molar ratio of manganese to iron in the compound to 6:4 to 7:3, the prepared positive electrode active material has a high specific capacity, and the prepared battery has good cycle performance.

[0060] In some embodiments, the anions of the compound include phosphate, carbonate, or oxalate.

[0061] By including phosphate, carbonate, or oxalate anions in the compound, the resulting positive electrode active material contains fewer impurities.

[0062] In some implementations, the carbon source includes organic carbon sources and / or inorganic carbon sources.

[0063] Organic carbon sources refer to organic substances that contain carbon elements and can be carbonized during sintering to form carbon materials.

[0064] Inorganic carbon sources refer to inorganic substances that contain carbon elements and can be carbonized during sintering to form carbon materials.

[0065] As an example, a carbon source may include only organic carbon sources, only organic carbon sources, or both organic and inorganic carbon sources.

[0066] When the carbon source includes organic carbon source and / or inorganic carbon source, the carbon source can be uniformly distributed on the surface of manganese ions and / or ferrous ions and form a thin film to constitute a conductive network. This allows carbon to not only be uniformly distributed on the surface of the compound grains, but also to be embedded inside the compound grains for in-situ doping and coating, thereby improving the conductivity and specific capacity of the positive electrode active material obtained from the phosphate-based positive electrode material precursor.

[0067] In some embodiments, the organic carbon source includes any one or more of glucose, starch, sucrose, fructose, cellulose, citric acid, and ascorbic acid; and / or, the inorganic carbon source includes any one or more of conductive carbon, graphene, conductive carbon fiber, and carbon nanotubes.

[0068] As an example, the organic carbon source may be glucose, starch, sucrose, fructose, cellulose, citric acid or ascorbic acid, or may be a mixture of glucose and sucrose, or may be a mixture of glucose and fructose, or may be a mixture of sucrose and fructose, or may be a mixture of citric acid and ascorbic acid.

[0069] The organic carbon source can be conductive carbon, graphene, conductive carbon fiber or carbon nanotube, or a mixture of conductive carbon and graphene, or a mixture of conductive carbon fiber and carbon nanotube, or a mixture of conductive carbon, graphene and carbon nanotube.

[0070] The aforementioned carbon sources can be uniformly distributed on the surface of manganese ions and / or ferrous ions to form a thin film, constituting a conductive network. This allows carbon to not only be uniformly distributed on the surface of the compound grains, but also to be embedded inside the compound grains for in-situ doping and coating, thereby improving the conductivity and specific capacity of the positive electrode active material obtained from the phosphate-based positive electrode material precursor.

[0071] In some implementations, the carbon source includes any one or more of ascorbic acid, citric acid, and carbon nanotubes.

[0072] As an example, the carbon source can be ascorbic acid, citric acid, or carbon nanotubes, or a mixture of ascorbic acid and citric acid.

[0073] By selecting the aforementioned carbon source, the conductivity and specific capacity of the positive electrode active material obtained from the phosphate-based positive electrode material precursor can be further improved.

[0074] This application also provides a method for preparing a phosphate-based cathode material precursor, which includes mixing a compound precursor and an acid solution to obtain a first mixture after preliminary crystallization, mixing the first mixture and an alkaline solution to obtain a second mixture and carrying out an aging reaction, adding a carbon source to the second mixture during the aging reaction, and obtaining a precursor suspension after the aging reaction is completed; the compound precursor includes manganese and / or iron.

[0075] The precursors of the compounds are metal salts and / or metal oxides containing manganese and / or iron.

[0076] Metal salts include manganese salts and / or iron salts.

[0077] Manganese salts include any one or more of manganese sulfate, manganese nitrate, manganese chloride, and manganese acetate; and / or, iron salts include any one or more of ferrous sulfate, ferrous nitrate, ferrous chloride, and ferrous acetate.

[0078] Optionally, the iron salt is ferrous sulfate; and / or, the manganese salt is manganese sulfate.

[0079] Alternatively, the metal salts include manganese salts and iron salts.

[0080] Optionally, the molar ratio of manganese ions to ferrous ions in the metal salt is 6:4 to 7:3.

[0081] Optionally, the molar ratio of manganese ions to ferrous ions in the metal salt is 6:4 or 7:3.

[0082] Metal salts are prepared by mixing a metal salt solution with an acid solution.

[0083] The total solute mass fraction in the metal salt solution is 30 wt% to 50 wt%.

[0084] Metal salt solutions can be prepared by the following methods:

[0085] Manganese salt and / or iron salt are dissolved in water according to a specified ratio and stirred until homogeneous to obtain a metal salt solution. The dissolution temperature is 20℃~70℃, and the dissolution time is 20min~100min.

[0086] Metal oxides include manganese oxides and iron oxides.

[0087] Manganese oxides include any one or more of manganese monoxide, manganese dioxide, manganese trioxide, and manganese tetroxide.

[0088] Iron oxides include any one or more of ferrous oxide, ferric oxide, and magnetite.

[0089] An acid solution is an acidic solution.

[0090] The acid solution includes any one or more of NH4H2PO4, (NH4)2HPO4, (NH4)3PO4, H3PO4 and oxalic acid.

[0091] Optionally, the acid solution is oxalic acid.

[0092] The mass fraction of the solute in the acid solution is 2 wt% to 65 wt%.

[0093] Acid solutions can be prepared by the following methods:

[0094] The acid is dissolved in water according to a specific ratio and stirred until homogeneous to obtain an acid solution. The dissolution temperature is 10℃~80℃, and the dissolution time is 20min~100min.

[0095] An alkaline solution is a solution that is alkaline.

[0096] The alkaline solution includes ammonia and / or sodium hydroxide.

[0097] Optionally, the alkaline solution is ammonia.

[0098] The method for preparing phosphate-based cathode material precursors in this application involves adding a carbon source to the precursor reaction solution. The carbon source can be uniformly distributed on the surface of manganese ions and / or ferrous ions, forming a thin film and constituting a conductive network. This allows carbon to not only be uniformly distributed on the surface of the compound grains but also to be embedded inside the compound grains for in-situ doping and coating, thereby improving the conductivity and specific capacity of the cathode active material obtained from the phosphate-based cathode material precursor. Simultaneously, the carbon source also acts as a dispersant in the reaction solution, ensuring uniform dispersion of ions during the preparation of the phosphate-based cathode material precursor, resulting in a more complete reaction and improved structural stability of the obtained cathode active material.

[0099] In some embodiments, the carbon source accounts for 0.5% to 10% of the mass of the compound precursor.

[0100] As an example, the mass of the carbon source can be 0.5%, 0.6%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10% of the mass of the compound precursor.

[0101] Optionally, the carbon source accounts for 0.5% to 3% of the mass of the compound precursor.

[0102] The carbon source layer in the phosphate-based cathode material precursor can act as a steric hindrance. By ensuring that the mass ratio of the carbon source to the mass of the compound precursor is within the aforementioned range, the particle size of the phosphate-based cathode material precursor can be controlled, thereby preventing excessive grain growth during the synthesis of the cathode active material, controlling the specific surface area of ​​the cathode active material, and improving the high-temperature performance of the obtained cathode active material.

[0103] In some embodiments, the molar ratio of total metal elements in the compound precursor to solute in the acid solution is 1:(0.6 to 1.3).

[0104] As an example, the molar ratio of total metal elements in the compound precursor to solute in the acid solution can be 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2 or 1:1.3.

[0105] Optionally, the molar ratio of total metal elements in the compound precursor to solute in the acid solution is 1:(1.01 to 1.3).

[0106] By keeping the molar ratio of total metal elements in the compound precursor to solute in the acid solution within the above range, the compound precursor and the acid solution can undergo a preliminary crystallization reaction.

[0107] In some embodiments, stirring is maintained during the mixing of the compound precursor and the acid solution at a stirring rate of 10 rpm / min to 100 rpm / min.

[0108] As an example, the stirring rate can be 10 rpm / min, 20 rpm / min, 30 rpm / min, 40 rpm / min, 50 rpm / min, 60 rpm / min, 70 rpm / min, 80 rpm / min, 90 rpm / min or 100 rpm / min.

[0109] By maintaining the above stirring rate during the mixing of the compound precursor and the acid solution, the compound precursor and the acid solution can be mixed evenly, thereby forming a homogeneous phase during the initial crystallization process.

[0110] The reaction time between the compound precursor and the acid solution is 3 min to 300 min.

[0111] The reaction temperature between the compound precursor and the acid solution is 10℃~100℃.

[0112] In some embodiments, the pH of the second mixture is 3 to 10.

[0113] As an example, the pH value of the second mixture can be 3, 4, 5, 6, 7, 8, 9 or 10.

[0114] By keeping the pH value of the second mixture within the above range, it is beneficial for the grains in the second mixture to grow and develop again during the aging reaction, while simultaneously carrying out carbon doping and coating, so that carbon is fully incorporated into the interior of the grains and coated on the surface of the grains.

[0115] In some implementations, the aging reaction time is 0.5 h to 10 h.

[0116] As an example, the aging reaction time can be 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h or 10h.

[0117] By keeping the aging reaction time within the above range, it is beneficial for the grains in the second mixture to grow and develop again during the aging reaction, thereby obtaining a phosphate-based cathode material precursor with a suitable particle size.

[0118] In some embodiments, stirring is maintained during the mixing of the first mixture and the alkaline solution and the aging reaction, with a stirring rate of 1 rpm / min to 50 rpm / min.

[0119] As an example, the stirring rate can be 1 rpm / min, 2 rpm / min, 5 rpm / min, 10 rpm / min, 20 rpm / min, 30 rpm / min, 40 rpm / min or 50 rpm / min.

[0120] By maintaining the above stirring rate during the mixing and aging process of the first mixture and the alkaline solution, the first mixture, the alkaline solution and the carbon source can be mixed evenly, and excessive grain growth of the phosphate-based cathode material precursor can be prevented, thereby controlling the particle size of the phosphate-based cathode material precursor.

[0121] The temperature at which the first mixture and the alkaline solution are mixed and aged is 10℃~100℃.

[0122] In some embodiments, after obtaining the precursor suspension, the precursor suspension is filtered and washed to obtain a wet precursor material, which is then dried at 90°C to 250°C for 3 to 10 hours to obtain a phosphate-based cathode material precursor.

[0123] As an example, the drying temperature of the precursor wet material can be 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃ or 250℃.

[0124] The drying time for the precursor wet material can be 3h, 4h, 5h, 6h, 7h, 8h, 9h or 10h.

[0125] Phosphate-based cathode material precursors can be obtained by sequentially filtering, washing, and low-temperature drying the precursor suspension. Low-temperature drying can reduce carbon volatilization and prevent carbon phase transition, resulting in high residual carbon content and low energy consumption, allowing the carbon source layer to remain inside the grains and not easily detach.

[0126] Filtration devices for filtering precursor suspensions include vacuum filters, vertical filters, or plate and frame filters.

[0127] Drying equipment for drying wet precursor materials includes blower dryers, disc dryers, fluidized bed dryers, flash dryers, spray dryers, tunnel furnaces, rotary kilns, or roller furnaces.

[0128] This application also provides a positive electrode active material, the raw materials of which include the above-mentioned phosphate-based positive electrode material precursor.

[0129] Positive electrode active materials can be prepared by the following methods:

[0130] The positive electrode active material is prepared by mixing a phosphate-based cathode material precursor, a lithium source, a carbon source, and water, and then performing processes such as sand milling, spray drying, sintering, and pulverization.

[0131] The positive electrode active material of this application has high conductivity and specific capacity.

[0132] In addition, the positive electrode, battery and power device of this application will be described below with appropriate reference to the accompanying drawings.

[0133] In one embodiment of this application, a battery is provided.

[0134] Typically, a 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.

[0135] [Positive electrode plate]

[0136] 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 the positive electrode active material of the third aspect of this application.

[0137] 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.

[0138] 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.).

[0139] 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.

[0140] 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.

[0141] 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.

[0142] [Negative electrode plate]

[0143] 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.

[0144] 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.

[0145] 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.).

[0146] 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 lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, 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.

[0147] 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).

[0148] 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.

[0149] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0150] 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.

[0151] [Electrolytes]

[0152] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0153] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0154] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0155] 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.

[0156] 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.

[0157] [Isolation membrane]

[0158] In some embodiments, the 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.

[0159] 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.

[0160] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0161] In some embodiments, the battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0162] In some implementations, the battery's outer packaging can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The battery's outer packaging can also be a soft pack, such as a pouch. The soft pack can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0163] This application does not impose any particular limitation on the shape of the battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 The example shown is a square-structured battery cell 5.

[0164] In some implementations, refer to Figure 2 The outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, the base 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. The positive electrode sheet, negative electrode sheet, and 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 number of electrode assemblies 52 contained in a single battery cell 5 can be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0165] In some implementations, the batteries can be assembled into battery modules, and the number of batteries contained in a 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.

[0166] Figure 3 This is battery module 4, used as an example. (See reference...) Figure 3 In battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0167] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0168] 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.

[0169] Figure 4 and Figure 5 This is battery pack 1 as an example. (See reference...) Figure 4 and Figure 5The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 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.

[0170] In addition, this application also provides an electrical device, which includes at least one of the battery, battery module, or battery pack provided in this application. The 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.

[0171] As the electrical device, a battery, battery module, or battery pack can be selected according to its usage requirements.

[0172] Figure 6 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0173] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can be powered by a battery.

[0174] Example

[0175] 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.

[0176] Example 1

[0177] This application includes embodiments of a phosphate-based cathode material precursor and its preparation method, and a cathode active material and its preparation method, comprising the following steps:

[0178] S1, Preliminary crystallization

[0179] According to the molar ratio of manganese to iron of 6:4, weigh out 1200g of MnSO4·H2O (product content ≥99%), 1300g of FeSO4·7H2O (product content ≥99%) and 5800g of deionized water, add them to the mixing tank A and stir to dissolve for 30 minutes to obtain a metal salt solution for later use.

[0180] According to the total metal ion to oxalic acid molar ratio of 1:1.015, weigh 1600g H2C2O4·2H2O (product content ≥99%) and 4000g pure water, add them to the stirring tank B and stir to dissolve for 30min, heat to 50℃ and keep warm to obtain oxalic acid solution.

[0181] The metal salt solution in stirred tank A was added to stirred tank B at a certain flow rate using a pump to react with the oxalic acid solution. The pump speed was adjusted to 150 mL / min. After the solution was fed, the mixture was stirred continuously at 10 rpm / min for 5 minutes to mix and undergo preliminary crystallization, thus obtaining the first mixture.

[0182] S2, aging reaction

[0183] The first mixture was transferred to an aging tank for aging. Ammonia was added to the aging tank to control the pH of the mixture to 4. 5g of ascorbic acid and 20g of citric acid were added to the aging tank. The mixture was kept at 30℃ and stirred continuously at 10rpm / min for 60min to obtain a precursor suspension.

[0184] S3. Preparation of lithium manganese iron phosphate cathode material precursor

[0185] The precursor suspension was filtered using a vacuum filter to achieve solid-liquid separation and obtain a precursor filter cake. The precursor filter cake was then washed with deionized water to remove impurities. The filter cake was washed five times with 2L of water each time using 10L of water to obtain a wet precursor material. The wet precursor material was then transferred to a forced-air drying oven and dried continuously at 150℃ for 5 hours to obtain lithium manganese iron phosphate cathode material precursor powder.

[0186] S4. Preparation of lithium manganese iron phosphate cathode material

[0187] 1000g of the prepared lithium manganese iron phosphate cathode material precursor powder was weighed, and 605g of lithium dihydrogen phosphate, 112g of glucose with a mass fraction of 7% and 1700g of pure water were weighed and mixed according to the metal ion to phosphorus molar ratio of 0.96:1.00. After sand milling, spray drying, sintering and pulverizing, the lithium manganese iron phosphate cathode material was obtained.

[0188] Comparative Example 1

[0189] This application includes comparative examples of a phosphate-based cathode material precursor and its preparation method, and a cathode active material and its preparation method, comprising the following steps:

[0190] S1, Crystallization

[0191] According to the molar ratio of manganese to iron of 6:4, weigh out 1200g of MnSO4·H2O (product content ≥99%), 1300g of FeSO4·7H2O (product content ≥99%) and 5800g of deionized water, add them to the mixing tank A and stir to dissolve for 30 minutes to obtain a metal salt solution for later use.

[0192] According to the total metal ion to oxalic acid molar ratio of 1:1.015, weigh 1600g H2C2O4·2H2O (product content ≥99%) and 4000g pure water, add them to the stirring tank B and stir to dissolve for 30min, heat to 50℃ and keep warm to obtain oxalic acid solution.

[0193] The metal salt solution in the stirred tank A was added to the stirred tank B at a certain flow rate using a pump to react with the oxalic acid solution. The pump speed was adjusted to 150 mL / min. After the solution was fed, the mixture was stirred continuously at 10 rpm / min for 60 min to mix and crystallize, thus obtaining the first mixture.

[0194] S2. Preparation of lithium manganese iron phosphate cathode material precursor

[0195] The precursor suspension was filtered using a vacuum filter to achieve solid-liquid separation and obtain a precursor filter cake. The precursor filter cake was then washed with deionized water to remove impurities. The filter cake was washed five times with 2L of water each time using 10L of water to obtain a wet precursor material. The wet precursor material was then transferred to a forced-air drying oven and dried continuously at 150℃ for 5 hours to obtain lithium manganese iron phosphate cathode material precursor powder.

[0196] S3. Preparation of lithium manganese iron phosphate cathode material

[0197] 1000g of the prepared lithium manganese iron phosphate cathode material precursor powder was weighed, and 605g of lithium dihydrogen phosphate, 112g of glucose with a mass fraction of 7% and 1700g of pure water were weighed and mixed according to the metal ion to phosphorus molar ratio of 0.96:1.00. After sand milling, spray drying, sintering and pulverizing, the lithium manganese iron phosphate cathode material was obtained.

[0198] Comparative Example 2

[0199] This application includes comparative examples of a phosphate-based cathode material precursor and its preparation method, and a cathode active material and its preparation method, comprising the following steps:

[0200] S1, Crystallization

[0201] According to the molar ratio of manganese to iron of 6:4, weigh out 1200g of MnSO4·H2O (product content ≥99%), 1300g of FeSO4·7H2O (product content ≥99%) and 5800g of deionized water, add them to the mixing tank A and stir to dissolve for 30 minutes to obtain a metal salt solution for later use.

[0202] According to the total metal ion to oxalic acid molar ratio of 1:1.015, weigh 1600g H2C2O4·2H2O (product content ≥99%) and 4000g pure water, add them to the stirring tank B and stir to dissolve for 30min, heat to 50℃ and keep warm to obtain oxalic acid solution.

[0203] The metal salt solution in the stirred tank A was added to the stirred tank B at a certain flow rate using a pump to react with the oxalic acid solution. The pump speed was adjusted to 150 mL / min. After the solution was fed, the mixture was stirred continuously at 10 rpm / min for 60 min to mix and crystallize, thus obtaining the precursor suspension.

[0204] S2. Preparation of lithium manganese iron phosphate cathode material precursor

[0205] The precursor suspension was filtered using a vacuum filter to achieve solid-liquid separation and obtain a precursor filter cake. The precursor filter cake was then washed with deionized water to remove impurities. The filter cake was washed five times with 2L of water each time using 10L of water to obtain a wet precursor material. The wet precursor material was then transferred to a forced-air drying oven and dried continuously at 150℃ for 5 hours to obtain lithium manganese iron phosphate cathode material precursor powder.

[0206] S3, carbon coating

[0207] Weigh 2.2 kg of the prepared lithium manganese iron phosphate cathode material precursor powder, prepare 3.3 kg of pure water with a solid content of 40%, put it into a mixing tank, and after the stirring is started, add the precursor, 5 g of ascorbic acid and 20 g of citric acid, and stir together for 30 min to obtain a mixed slurry; then spray dry the mixed slurry with an inlet temperature of 300℃, an outlet temperature of 90℃, and an atomizer linear velocity >200 m / s. After drying, carbon-coated lithium manganese iron phosphate cathode material precursor is obtained.

[0208] S4. Preparation of lithium manganese iron phosphate cathode material

[0209] 1000g of carbon-coated lithium manganese iron phosphate cathode material precursor was weighed, and 605g of lithium dihydrogen phosphate, 112g of glucose with a mass fraction of 7% and 1700g of pure water were weighed and mixed according to the metal ion to phosphorus molar ratio of 0.96:1.00. After sand milling, spray drying, sintering and pulverizing, lithium manganese iron phosphate cathode material was obtained.

[0210] Comparative Example 3

[0211] This application includes comparative examples of a phosphate-based cathode material precursor and its preparation method, and a cathode active material and its preparation method, comprising the following steps:

[0212] S1, Crystallization

[0213] According to the molar ratio of manganese to iron of 6:4, weigh out 1200g of MnSO4·H2O (product content ≥99%), 1300g of FeSO4·7H2O (product content ≥99%) and 5800g of deionized water, add them to the mixing tank A and stir to dissolve for 30 minutes to obtain a metal salt solution for later use.

[0214] According to the total metal ion to oxalic acid molar ratio of 1:1.015, weigh 1600g H2C2O4·2H2O (product content ≥99%) and 4000g pure water, add them to the stirring tank B and stir to dissolve for 30min, heat to 50℃ and keep warm to obtain oxalic acid solution.

[0215] The metal salt solution in the stirred tank A was added to the stirred tank B at a certain flow rate using a pump to react with the oxalic acid solution. The pump speed was adjusted to 150 mL / min. After the solution was fed, the mixture was stirred continuously at 10 rpm / min for 60 min to mix and crystallize, thus obtaining the first mixture.

[0216] S2. Preparation of lithium manganese iron phosphate cathode material precursor

[0217] The precursor suspension was filtered using a vacuum filter to achieve solid-liquid separation and obtain a precursor filter cake. The precursor filter cake was then washed with deionized water to remove impurities. The filter cake was washed five times with 2L of water each time using 10L of water to obtain a wet precursor material. The wet precursor material was then transferred to a forced-air drying oven and dried continuously at 150℃ for 5 hours to obtain lithium manganese iron phosphate cathode material precursor powder.

[0218] S3, carbon coating

[0219] Weigh 2.2 kg of the prepared lithium manganese iron phosphate cathode material precursor powder, prepare 3.3 kg of pure water with a solid content of 40%, put it into a mixing tank, add the precursor and 25 g of carbon nanotubes after stirring is started, stir together for 30 min to obtain a mixed slurry; then spray dry the mixed slurry with an inlet temperature of 300℃, an outlet temperature of 90℃, and an atomizer linear velocity >200 m / s. After drying, carbon-coated lithium manganese iron phosphate cathode material precursor is obtained.

[0220] S4. Preparation of lithium manganese iron phosphate cathode material

[0221] 1000g of carbon-coated lithium manganese iron phosphate cathode material precursor was weighed, and 605g of lithium dihydrogen phosphate, 112g of glucose with a mass fraction of 7% and 1700g of pure water were weighed and mixed according to the metal ion to phosphorus molar ratio of 0.96:1.00. After sand milling, spray drying, sintering and pulverizing, lithium manganese iron phosphate cathode material was obtained.

[0222] The relevant parameters of the phosphate-based cathode material precursors and their preparation methods in Examples 1-14 and Comparative Examples 1-3, as well as the cathode active materials and their preparation methods, are shown in Table 1 below.

[0223] Table 1. Parameter results of Examples 1-14 and Comparative Examples 1-3

[0224]

[0225]

[0226]

[0227] In the preliminary crystallization steps of Examples 1 to 14, the acid solution used was 1600g H2C2O4·2H2O (product content ≥99%), the total metal ion to oxalic acid molar ratio was 1:1.015, the pH value of the mixture after adding ammonia to the aging tank in the aging reaction step was 4, the aging time was 1h, and after adding 5g ascorbic acid and 20g citric acid to the aging tank, the stirring rate was maintained at 10rpm / min. In the preparation of lithium manganese iron phosphate cathode material precursor, the drying temperature was 150℃ and the drying time was 5h.

[0228] In addition, the X-ray energy dispersive spectroscopy (EDS) spectra of the lithium manganese iron phosphate cathode material precursor prepared in Example 1 were obtained as follows: Figures 7-11 As shown, scanning electron microscope (SEM) images of the lithium manganese iron phosphate cathode materials prepared in Example 1 and Comparative Example 1 are as follows. Figures 12-13 As shown in Tables 2-3, the resistivity and specific surface area of ​​the lithium manganese iron phosphate cathode materials prepared in Examples 1-14 and Comparative Examples 1-3 were measured. The lithium manganese iron phosphate cathode materials of Examples 1-14 and Comparative Examples 1-3 were then used to prepare coin cells for performance testing. The test results are shown in Tables 2-3 below.

[0229] (1) X-ray energy dispersive spectroscopy test procedure for cathode material precursor

[0230] Equipment: ZEISS, Sigma 300, Oxford Ultra MAX;

[0231] Detailed operation steps:

[0232] S1. On-site testing environment: temperature 15~28℃, relative humidity <80%.

[0233] S2. Preparation before testing: Turn on the air compressor and circulator to preheat for 10-15 minutes, then enter the software to turn on the electron gun "EHT" and high pressure, and keep the electron gun vacuum below 2*10-9mbar.

[0234] S3. Sample weighing and preparation: Weigh 2g of the powder sample to be tested using an electronic balance, put the powder into a sample container coated with conductive adhesive using a spatula, and place the container into a sample stage coated with conductive adhesive (select whether to spray gold treatment according to the conductivity of the sample).

[0235] S4. Equipment parameter settings: Test range: B~U, Detection limit: 0.1~0.5% / Testrange:BU, Detection limit: 0.1~0.5%wt.

[0236] S5. Pre-test debugging: Click “Vent” to release the vacuum. After completion, open the sample chamber to inject the sample, and then click “Pump” to draw a vacuum. After the value is 5*10-5mbar, click “stage” to find the sample stage to be tested. Double-click the sample to be tested, and the device will automatically position it under the electron gun. Use the operating lever or mouse and keyboard to adjust the appropriate working distance, turn on the high voltage, and select the appropriate area to focus.

[0237] S6. Sample Testing: Adjust the appropriate contrast, brightness, and magnification on the operating table, open the EDS Aztec testing software, input the test sample information, select the area to be tested, and start scanning the image. Perform surface scanning, point scanning, or other scanning methods on the area to be tested.

[0238] S7. Data Analysis: After completing the above operations, use both spectral peak and reconstructed peak methods to confirm the elements, and click "Report Results". The system will automatically generate and save the analysis report.

[0239] (2) Testing Procedure for Scanning Electron Microscopy Images of Cathode Materials

[0240] The microstructure of lithium manganese iron phosphate cathode materials in Example 1 and Comparative Example 1 was observed using a scanning electron microscope (SEM, instrument brand: ZEISS Sigma 300).

[0241] (3) Powder resistivity testing procedure for positive electrode materials

[0242] Equipment: Powder resistivity tester (brand: Suzhou Jingge, model: ST-2722 semiconductor powder resistivity tester, 30Mpa four probes);

[0243] Method: Tested according to GB / T 30835-2014;

[0244] Test environment: temperature 20-30℃, relative humidity <65%;

[0245] Specific steps:

[0246] S1. Sample weighing: Weigh 1g of the powder sample to be tested using an electronic balance.

[0247] S2. Mold cleaning: Use lint-free paper soaked in anhydrous ethanol to clean the inner cavity of the mold and the upper and lower gaskets until there are no visible stains on the lint-free paper. Place the cleaned mold into the limiting groove in the instrument.

[0248] S3. Instrument parameter setting: Open the software, select the appropriate test principle mode according to the sample type, input the test parameters, perform air pressure test, and reset the thickness.

[0249] S4. Sample Testing: After the thickness reset is complete, carefully pour the weighed sample into the mold cavity, being careful not to let it stick to the wall or overflow. Ensure that the powder surface is flat, place the upper terminal, and gently flatten it. Place the mold with the sample in the limiting groove of the instrument test stage to start the test.

[0250] S5. Data Recording: The instrument automatically calculates, takes the average of the positive and negative values, and records them.

[0251] (4) Test procedure for specific surface area of ​​cathode material

[0252] Equipment: Nitrogen adsorption specific surface area and pore size analyzer (Brand: Micromertics, Model: AUY220);

[0253] Method: Tested according to GB / T 19587-2017;

[0254] Specific steps:

[0255] S1. Sample weighing: Weigh 2g of the powder sample to be tested using an electronic balance.

[0256] S2. Vacuum degassing and sample tube installation: After degassing the sample tube, install it on the instrument. Sample tubes are not allowed to be installed on other pipelines. When installing the sample tube, first put the sealing ring on the sample tube and tighten the screws on the sample tube at the same time.

[0257] S3. Instrument Start-up and Parameter Settings: Open the valves of the high-purity helium and nitrogen cylinders, control the pressure at 0.08-0.12 MPa, and after ventilating for about 3-5 minutes, turn on the instrument power switch in sequence, start the test software, click "System Preheating", adjust the flow rate and preheat for 20-30 minutes. After preheating is complete, fill in the parameters (gas flow rate parameter settings: 0.25, 0.20, 0.15, 0.10, 0.06; quantitative tube volume parameter setting: 2.716).

[0258] S4. Liquid nitrogen preparation: Pour the liquid nitrogen from the liquid nitrogen container into the liquid nitrogen cup. When pouring the liquid nitrogen, be careful not to let the liquid nitrogen come into contact with your skin. The liquid level should be about 3 cm from the mouth of the cup. Place the liquid nitrogen cup on the lifting plate.

[0259] S5. Click "Start Adsorption" to begin the test.

[0260] S6. Data Processing: After the test is completed, click "Report" to view the test file, find the corresponding sample number, click "summary" to read the data displayed in "BET Surface-Area" as the final result and record it.

[0261] (5) Button battery testing procedures under constant temperature conditions of 25±2℃

[0262] 10g of the positive electrode material prepared in each example and comparative example was weighed out to fabricate CR2430 coin cells. The cells were tested using a Lamborghini BT2018AS tester. The testing method is as follows:

[0263] S1, 0.1C button cell test under constant temperature conditions of 25±2℃

[0264] S11, Let stand for 180 minutes;

[0265] S12, 0.1C constant current charging to 4.30V;

[0266] S13, 4.30V constant voltage charging until the current is less than 0.05C;

[0267] S14. Let stand for 5 minutes;

[0268] S15, 0.1C constant current discharge to 2.00V;

[0269] S16. Let stand for 5 minutes.

[0270] S2. Cycle life test procedure:

[0271] Test environment: under constant temperature conditions of 25±2℃

[0272] S21. Let stand for 180 minutes;

[0273] S22, 0.1C constant current charging to 4.30V;

[0274] S23, 4.30V constant voltage charging until the current is less than 0.05C;

[0275] S24. Let stand for 5 minutes;

[0276] S25, constant current discharge at 0.1C to 2.00V, yielding the initial discharge capacity.

[0277] S26. Let stand for 5 minutes;

[0278] S27, Cyclic test: 0.33C constant current charging to 4.30V;

[0279] S28, 4.30V constant voltage charging until the current is less than 0.05C;

[0280] S29. Let stand for 5 minutes;

[0281] S30, 0.33C constant current discharge to 2.00V, to obtain the discharge capacity of one cycle;

[0282] S31. Let stand for 5 minutes;

[0283] S32. Repeat steps S26 to S31 until the discharge capacity accounts for 80% of the initial discharge capacity. Record the number of cycles at this point, which is the cycle life.

[0284] CR2430 button cell is produced by the following method:

[0285] Positive electrode sheet:

[0286] Lithium manganese iron phosphate, conductive carbon black, and PVDF are mixed in a mass ratio of 90:5:5, and then N-methylpyrrolidone solvent is added. The mixture is coated on one side of aluminum foil, and after cold pressing and cutting, a positive electrode sheet is obtained. The positive electrode is then punched into a positive electrode film of a specified diameter.

[0287] Negative electrode plate:

[0288] The negative electrode is a lithium sheet of a specified diameter;

[0289] Separating membrane:

[0290] A polyethylene film with a thickness of 13 μm was used as the separator.

[0291] Electrolyte:

[0292] Ethylene carbonate, diethyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 1:1:1. LiPF6 was then dissolved in this solution to obtain an electrolyte. The concentration of LiPF6 in this electrolyte was 1 mol / L.

[0293] Assembly:

[0294] Assembly is carried out in a glove box filled with dry nitrogen, where the moisture and oxygen content is less than 0.1 ppm. Qualified small round plates are placed on the positive electrode side of the coin cell casing, which has a gasket placed in place beforehand, with the coated side facing away from the positive electrode. Then, 1-2 drops of electrolyte are added to the positive electrode plate, followed by the separator and 1-2 drops of electrolyte. Next, the pure lithium sheet, gasket, and spring are placed, and finally, the negative electrode side of the coin cell casing is placed on top. After assembly, the casing is sealed using a sealing machine.

[0295] (6) High-temperature storage performance test at 60℃

[0296] Formula for calculating capacity retention:

[0297] Capacity retention rate = (Discharge capacity after high-temperature storage on a certain day / Initial discharge capacity) * 100%;

[0298] Button battery testing procedures under 60℃ high temperature conditions:

[0299] S1, Initial charge / discharge (initial discharge capacity):

[0300] S11, Let stand for 180 minutes;

[0301] S12, 0.1C constant current charging to 4.30V;

[0302] S13, 4.30V constant voltage charging until the current is less than 0.05C;

[0303] S14. Let stand for 5 minutes;

[0304] S15, 0.1C constant current discharge to 2.00V;

[0305] S16. Let stand for 5 minutes;

[0306] S17, then charge at a constant current of 0.1C to 4.30V;

[0307] S18, 4.30V constant voltage charging until the current is less than 0.05C;

[0308] S19. After charging is complete, place the battery in a 60℃ constant temperature chamber and let it stand.

[0309] S20. The step ends, and the discharge data from step e is used as the initial discharge capacity.

[0310] S2, High-temperature storage data on day 30:

[0311] S21. Remove the battery from the 60℃ constant temperature chamber on the 30th day of resting.

[0312] S22. Discharge to 2.00V at a constant current of 0.1C under constant temperature conditions of 25±2℃;

[0313] S23, let stand for 5 minutes;

[0314] S24, 0.1C constant current charging to 4.30V;

[0315] S25, 4.30V constant voltage charging until the current is less than 0.05C;

[0316] S26. Let stand for 5 minutes;

[0317] S27, 0.1C constant current discharge to 2.00V;

[0318] S28. Let stand for 5 minutes;

[0319] S29, then charge at a constant current of 0.1C to 4.30V;

[0320] S210, 4.30V constant voltage charging until the current is less than 0.05C;

[0321] S211. After charging is complete, place the battery back into the 60℃ constant temperature chamber and let it stand.

[0322] S212. The step ends, and the discharge data of step g is used as the discharge capacity stored on day 30.

[0323] S213, 30-day high-temperature storage capacity retention rate calculation: (30-day storage discharge capacity / initial discharge capacity) * 100%.

[0324] S3, High-Temperature Storage Data on Day 90:

[0325] S31. Remove the battery from the 60℃ constant temperature chamber on the 90th day of rest.

[0326] S32. Discharge to 2.00V at a constant current of 0.1C under constant temperature conditions of 25±2℃;

[0327] S33, let stand for 5 minutes;

[0328] S34, 0.1C constant current charging to 4.30V;

[0329] S35, 4.30V constant voltage charging until the current is less than 0.05C;

[0330] S36. Let stand for 5 minutes;

[0331] S37, 0.1C constant current discharge to 2.00V;

[0332] S38, let stand for 5 minutes;

[0333] S39, then charge at a constant current of 0.1C to 4.30V;

[0334] S310, 4.30V constant voltage charging until the current is less than 0.05C;

[0335] S311. After charging is complete, place the battery back into the 60℃ constant temperature chamber and let it stand.

[0336] S312. The step ends, and the discharge data of step g is used as the discharge capacity stored on day 90.

[0337] S313, 30-day high-temperature storage capacity retention rate calculation: (90-day storage discharge capacity / initial discharge capacity) * 100%.

[0338] S4. High-temperature storage data on day 180, day 270, and day 360: Same as the steps above.

[0339] Please refer to Figures 7-11 The lithium manganese iron phosphate cathode material precursor prepared in Example 1 contains C, Fe, Mn and O elements. The C element is uniformly distributed inside the crystal grains formed by the compound and coated on the surface of the crystal grains formed by the compound.

[0340] Please refer to Figures 12-13 The lithium manganese iron phosphate cathode material prepared in Example 1 has more rounded particles and better uniformity than the lithium manganese iron phosphate cathode material prepared in Comparative Example 1.

[0341] Table 2 Performance test results of Examples 1-14 and Comparative Examples 1-3

[0342]

[0343]

[0344]

[0345] As can be seen from Examples 1 to 12, by distributing a carbon source layer both inside and on the surface of the precursor of lithium manganese iron phosphate, the resistivity of the prepared lithium manganese iron phosphate cathode material is ≤280Ω·mm, and the specific capacity of the prepared battery at room temperature 0.1C charging is 151mAh / g to 155.1mAh / g, and the specific capacity at room temperature 0.1C discharging is 144mAh / g to 149.8mAh / g.

[0346] A comparison of Examples 1 and 3 with Examples 4 and 5 shows that when the molar ratio of manganese to iron in the precursor compounds of lithium manganese iron phosphate in Examples 1 and 3 is 6:4 to 7:3, the molar ratios of manganese to iron in the precursor compounds of lithium manganese iron phosphate in Examples 4 and 5 are 4:6 and 8:2, respectively. The batteries prepared in Examples 1 and 3 have higher specific capacity and specific capacity at room temperature 0.1C compared to those prepared in Examples 4 and 5, and also have a longer cycle life at room temperature (25°C 0.33C cycle @ 80% SOH).

[0347] A comparison of Examples 1 and 6-9 shows that the higher the mass percentage of the carbon source relative to the mass of the compound precursor, the larger the specific surface area of ​​the prepared lithium manganese iron phosphate cathode material. Furthermore, as the mass percentage of the carbon source relative to the mass of the compound precursor increases, the powder resistivity of the prepared lithium manganese iron phosphate cathode material first decreases and then increases. When the mass percentage of the carbon source relative to the mass of the compound precursor is 1%, the powder resistivity of the prepared lithium manganese iron phosphate cathode material is the lowest, at 17.5 Ω·mm. Moreover, when the mass percentage of the carbon source relative to the mass of the compound precursor exceeds 10% (12% in Example 9), the specific capacity of the battery at 0.1C charging and discharging at 0.1C is relatively low.

[0348] A comparison of Example 1 and Examples 10-11 shows that Example 1 uses ascorbic acid and citric acid as carbon sources, while Examples 10-11 use sucrose and glucose as carbon sources, respectively. The lithium manganese iron phosphate cathode material prepared in Example 1 has a lower powder resistivity than that prepared in Examples 10-11, and the battery prepared in Example 1 has a higher specific capacity at room temperature 0.1C and a higher specific capacity at room temperature 0.1C than that prepared in Examples 10-11.

[0349] A comparison of Example 2 and Example 12 shows that Example 2 uses carbon nanotubes as the carbon source, while Example 12 uses conductive carbon as the carbon source. The powder resistivity of the lithium manganese iron phosphate cathode material prepared in Example 2 is lower than that in Example 12. The specific capacity of the battery prepared in Example 2 at 0.1C and at room temperature at 0.1C are higher than those in Example 12.

[0350] A comparison of Example 1 and Comparative Example 1 shows that Example 1, by distributing carbon sources both inside and on the surface of the lithium manganese iron phosphate precursor grains, achieves better results. In Comparative Example 1, the lithium manganese iron phosphate precursor lacks carbon source embedding or coating. The powder resistivity of the lithium manganese iron phosphate cathode material prepared in Example 1 is only 17.5 Ω·mm, lower than the 725 Ω·mm of the lithium manganese iron phosphate cathode material prepared in Comparative Example 1. The specific capacity of the battery prepared in Example 1 at room temperature and 0.1C charging is 154 mAh / g, higher than that of the battery prepared in Comparative Example 1. The 0.1C charging capacity at room temperature is 148 mAh / g; the 0.1C discharge capacity at room temperature of the battery prepared in Example 1 is 148.7 mAh / g, which is higher than the 0.1C discharge capacity at room temperature of 141 mAh / g of the battery prepared in Comparative Example 1; the cycle life at room temperature of the battery prepared in Example 1 (25℃ 0.33C cycle @ 80% SOH) is 1600 cls, which is higher than the 800 cls of the cycle life at room temperature of the battery prepared in Comparative Example 1 (25℃ 0.33C cycle @ 80% SOH).

[0351] A comparison of Example 1 and Comparative Example 2 shows that Example 1, by distributing carbon sources both inside and on the surface of the lithium manganese iron phosphate precursor grains, and Comparative Example 2, by coating the carbon source after preparing the lithium manganese iron phosphate precursor, resulted in a lower powder resistivity of only 17.5 Ω·mm for the lithium manganese iron phosphate cathode material, compared to 530 Ω·mm for the lithium manganese iron phosphate cathode material prepared in Comparative Example 2. Furthermore, the specific capacity of the battery prepared in Example 1 at 0.1C charging at room temperature was 154 mAh / g, which was higher than that of the battery prepared in Comparative Example 2. The charge capacity at 0.1C at room temperature is 149 mAh / g; the discharge capacity at 0.1C at room temperature of the battery prepared in Example 1 is 148.7 mAh / g, which is higher than the discharge capacity at 0.1C at room temperature of 142 mAh / g of the battery prepared in Comparative Example 2; the cycle life at room temperature of the battery prepared in Example 1 (25℃ 0.33C cycle @ 80% SOH) is 1600 cls, which is higher than the cycle life at room temperature of the battery prepared in Comparative Example 2 (25℃ 0.33C cycle @ 80% SOH) by 880 cls.

[0352] A comparison of Example 2 and Comparative Example 3 shows that Example 2, by distributing carbon sources both inside and on the surface of the lithium manganese iron phosphate precursor grains, and Comparative Example 2, by coating the lithium manganese iron phosphate precursor with carbon sources after preparation, resulted in a powder resistivity of only 12.8 Ω·mm for the lithium manganese iron phosphate cathode material prepared in Example 2, which is lower than the powder resistivity of 412 Ω·mm for the lithium manganese iron phosphate cathode material prepared in Comparative Example 3. Furthermore, the specific capacity of the battery prepared in Example 2 at room temperature and 0.1C charging is 155.1 mAh / g, which is higher than that of the comparative example. The battery prepared in Example 3 has a room temperature 0.1C charging capacity of 149.5 mAh / g; the battery prepared in Example 2 has a room temperature 0.1C discharge capacity of 149.8 mAh / g, which is higher than the room temperature 0.1C discharge capacity of 142.5 mAh / g of the battery prepared in Comparative Example 3; the battery prepared in Example 2 has a room temperature cycle life (25℃ 0.33C cycle @ 80% SOH) of 1450 cls, which is higher than the room temperature cycle life (25℃ 0.33C cycle @ 80% SOH) of the battery prepared in Comparative Example 3.

[0353] @80%SOH)850cls.

[0354] As can be seen from Example 13, by distributing a carbon source layer both inside and on the surface of the precursor of lithium manganese phosphate, the resistivity of the prepared lithium manganese phosphate cathode material is 35 Ω·mm, and the battery prepared has a specific capacity of 150.4 mAh / g at room temperature and a specific capacity of 145 mAh / g at room temperature and 0.1C discharge.

[0355] As can be seen from Example 14, by distributing a carbon source layer both inside and on the surface of the lithium iron phosphate precursor grains, the resistivity of the prepared lithium iron phosphate cathode material is 16 Ω·mm, and the specific capacity of the prepared battery at room temperature 0.1C charging is 162.07 mAh / g and the specific capacity at room temperature 0.1C discharging is 159.02 mAh / g.

[0356] Table 3. High-temperature performance test results of Examples 1, 2-5 and Comparative Example 1

[0357]

[0358] As shown in Examples 1, 6-9, when the mass of the carbon source in Examples 1, 6-8 accounts for 0.5% to 10% of the mass of the compound precursor, the capacity retention rate of the battery after storage at 60°C for 30 days is 95% to 98%, after storage at 60°C for 90 days, the capacity retention rate is 92% to 95.5%, after storage at 60°C for 180 days, the capacity retention rate is 90% to 94%, after storage at 60°C for 270 days, the capacity retention rate is 88.2% to 92.8%, and after storage at 60°C for 360 days, the capacity retention rate is 87% to 92%. In Example 9, when the mass of the carbon source accounts for 12% of the mass of the compound precursor, the capacity retention rate of the battery after storage at 60°C for 30, 90, 180, 270, and 360 days is relatively low. As the mass percentage of the carbon source relative to the mass of the compound precursor increases, the capacity retention of the battery after storage at 60°C for 30d, 90d, 180d, 270d, and 360d initially increases and then decreases. Furthermore, when the mass percentage of the carbon source relative to the mass of the compound precursor is 1%, the battery exhibits the highest capacity retention after storage at 60°C for 30d, 90d, 180d, 270d, and 360d.

[0359] As can be seen from the comparison between Examples 1, 6-9 and Comparative Example 1, Examples 1 and 6-9 have carbon sources distributed both inside and on the surface of the precursor of lithium manganese iron phosphate, while the precursor of lithium manganese iron phosphate in Comparative Example 1 has no carbon source embedded or coated. The capacity retention rates of the batteries of Examples 1 and 6-9 after storage at 60°C for 30d, 90d, 180d, 270d and 360d are higher than those of the battery of Comparative Example 1 after storage at 60°C for 30d, 90d, 180d, 270d and 360d.

[0360] 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 phosphate-based cathode material precursor, characterized in that, The phosphate-based cathode material precursor includes a compound and a carbon source layer, wherein the carbon source layer is distributed inside the grains formed by the compound and covers the surface of the grains formed by the compound. The compound contains iron and / or manganese.

2. The phosphate-based cathode material precursor according to claim 1, characterized in that, The molar ratio of manganese to iron in the compound is 6:4 to 7:

3.

3. The phosphate-based cathode material precursor according to claim 1 or 2, characterized in that, The anions of the compound include phosphate, carbonate, or oxalate.

4. The method for preparing the phosphate-based cathode material precursor according to any one of claims 1 to 3, characterized in that, The carbon source includes organic carbon sources and / or inorganic carbon sources.

5. The method for preparing the phosphate-based cathode material precursor according to claim 4, characterized in that, The organic carbon source includes any one or more of glucose, starch, sucrose, fructose, cellulose, citric acid, and ascorbic acid; and / or, The inorganic carbon source includes any one or more of conductive carbon, graphene, conductive carbon fiber, and carbon nanotubes.

6. The method for preparing the phosphate-based cathode material precursor according to claim 4, characterized in that, The carbon source includes any one or more of ascorbic acid, citric acid, and carbon nanotubes.

7. A method for preparing a phosphate-based cathode material precursor, characterized in that, The preparation method of the phosphate-based cathode material precursor includes: mixing the compound precursor and an acid solution to obtain a first mixture after preliminary crystallization; mixing the first mixture and an alkaline solution to obtain a second mixture and carrying out an aging reaction; adding a carbon source to the second mixture during the aging reaction; and obtaining a precursor suspension after the aging reaction is completed. The compound precursor includes manganese and / or iron.

8. The method for preparing the phosphate-based cathode material precursor according to claim 7, characterized in that, The carbon source accounts for 0.5% to 10% of the mass of the compound precursor.

9. The method for preparing the phosphate-based cathode material precursor according to claim 7 or 8, characterized in that, The molar ratio of total metal elements in the compound precursor to solute in the acid solution is 1:(0.6-1.3).

10. The method for preparing the phosphate-based cathode material precursor according to any one of claims 7 to 9, characterized in that, During the mixing of the compound precursor and the acid solution, stirring is maintained at a speed of 10 rpm / min to 100 rpm / min.

11. The method for preparing the phosphate-based cathode material precursor according to any one of claims 7 to 10, characterized in that, The pH value of the second mixture is 3 to 10.

12. The method for preparing the phosphate-based cathode material precursor according to any one of claims 7 to 11, characterized in that, The aging reaction takes 0.5 h to 10 h.

13. The method for preparing the phosphate-based cathode material precursor according to any one of claims 7 to 12, characterized in that, During the mixing and aging process of the first mixture and the alkaline solution, stirring is maintained at a speed of 1 rpm / min to 50 rpm / min.

14. The method for preparing the phosphate-based cathode material precursor according to any one of claims 7 to 13, characterized in that, After obtaining the precursor suspension, the precursor suspension is filtered and washed to obtain a wet precursor material. The wet precursor material is then dried at 90℃~250℃ for 3h~10h to obtain a phosphate-based cathode material precursor.

15. A positive electrode active material, characterized in that, The raw materials for the positive electrode active material include the phosphate-based positive electrode material precursor according to any one of claims 1 to 6 or the phosphate-based positive electrode material precursor prepared by the preparation method of the phosphate-based positive electrode material precursor according to any one of claims 7 to 14.

16. A single battery cell, characterized in that, The battery cell includes a positive electrode sheet, and the positive electrode sheet includes the positive electrode active material as described in claim 15.

17. A battery, characterized in that, The battery comprises the battery cell of claim 16.

18. An electrical appliance, characterized in that, The electrical device includes the battery as described in claim 17.

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