Precursor material and preparation method thereof, positive electrode material and preparation method thereof, positive electrode plate, battery and electric device

Abstract

The invention provides a precursor material and a preparation method thereof, a positive electrode material and a preparation method thereof, a positive electrode plate, a battery and an electric device. The precursor material provided by the invention comprises a compound Mn < x > Fe < y > M (1-x-y) C < 2 > O < 4 >. 2H < 2 > O, wherein 0 < x < = 0.9, 0 < y < = 0.9, and 0.9 < = x + ult; m comprises one or more metal elements in group IIA, group IIIA, group IVA, group IB, group IIB, group IIIB, group IVB, group VB, group VIB and group VIII. Manganese, iron and doped elements in the precursor material are uniformly distributed, the element distribution of the prepared positive electrode material is uniform, the batch consistency is good, and the specific capacity and the cycle performance of the battery are improved.

Description

Technical Field

[0001] The present application relates to the technical field of lithium batteries, and in particular to a precursor material, a method for preparing the precursor material, a positive electrode material and a method for preparing the same, a positive electrode sheet, a battery, and an electrical device. Background Art

[0002] In recent years, the application of secondary batteries has become increasingly widespread. They are widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power stations, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields. As secondary batteries have achieved great development, higher requirements have been placed on their energy density, cycle performance, and other aspects. Summary of the Invention

[0003] This application is made in view of the above-mentioned problems, and its purpose is to provide a precursor material and preparation method thereof, a positive electrode material and preparation method thereof, a positive electrode plate, a battery, and an electrical device. The manganese, iron, and doping elements in the precursor material of this application are evenly distributed and have good batch consistency. The elements of the prepared positive electrode material are evenly distributed and have good batch consistency, thereby improving the specific capacity and cycle performance of the battery.

[0004] In order to achieve the above-mentioned object, the present application provides a precursor material in the first aspect, including the compound Mn x Fe y M (1-x-y) C2O4·2H2O; wherein, 0<x≤0.9, 0<y≤0.9, 0.9≤x+y<1, and M includes one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIII, and Group VIII.

[0005] Therefore, the manganese, iron and doping elements in the precursor material of the present application are evenly distributed and have good batch consistency. The elements in the positive electrode material prepared using the precursor material of the present application are evenly distributed and have good batch consistency, thereby improving the specific capacity and cycle performance of the prepared battery.

[0006] In any embodiment, 0.49≤x≤0.686; and / or,

[0007] 0.29≤y≤0.49; and / or,

[0008] 0.98≤x+y<1; and / or,

[0009] The M includes one or more elements selected from titanium, vanadium, chromium, copper, magnesium, aluminum, zinc, cobalt, nickel, tin, niobium, tungsten, zirconium, tantalum, cerium, and europium.

[0010] In any embodiment, the Dv50 particle size of the precursor material is 8-100 μm.

[0011] The Dv50 particle size of the precursor material of the present application is within the above range, which is beneficial to the washing and filtering operations during the precursor preparation process on the one hand, and is beneficial to the suspension of the precursor particles and is not easy to settle when preparing the positive electrode material, thereby improving the efficiency of the mixing and grinding process.

[0012] In any embodiment, the precursor material has a compacted density of 1.1-3.0 g / cm at 30 MPa. 3 .

[0013] The compaction density of the precursor material of the present application is within the above range, which is beneficial to increasing the compaction density of the positive electrode material, thereby improving the specific capacity of the battery.

[0014] In any embodiment, the compound Mn in the precursor material x Fe y M (1-x-y) The weight content of C2O4·2H2O is 98.5%-99.98%.

[0015] The precursor material of the present application has a high compound content and a low impurity content, so the impurity content of the prepared positive electrode material is low and the specific capacity of the battery is improved.

[0016] The second aspect of the present application also provides a method for preparing a precursor material, comprising the following steps:

[0017] Dissolving a soluble manganese source, a soluble iron source, and a soluble source of an element M in a solvent to obtain a solution; wherein the element M comprises one or more metal elements from Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIII, and Group VIII;

[0018] adding the solution to an oxalic acid solution and reacting to obtain a reaction product;

[0019] The pH value of the reaction product is adjusted to 0.5-4, the solid-liquid separation is carried out, and the solid phase is collected and dried to obtain a precursor material.

[0020] Thus, the method of the present application causes oxalate to coprecipitate with manganese ions, iron ions, and M element ions, thereby improving the uniformity of the distribution of each element in the material and batch consistency; by adjusting the pH value, the coprecipitation reaction is made more complete, thereby improving the product yield; and by controlling the addition sequence and adjusting the pH value, the entry of cationic impurities into the reaction product is reduced, thereby improving the purity and content stability of the precursor material; thereby improving the specific capacity and cycle performance of the battery.

[0021] In any embodiment, the solution is added to an oxalic acid solution and reacted at 15° C. to 95° C.; and / or,

[0022] The solution addition time is 5-300 min, optionally 10-300 min; and / or,

[0023] The molar ratio of oxalic acid in the oxalic acid solution to the total amount of metal elements in the solution is 0.7-2; and / or,

[0024] The total concentration of metal elements in the solution is 1-3 mol / L; and / or,

[0025] The oxalic acid concentration in the oxalic acid solution is 1-3 mol / L; and / or,

[0026] The molar amount of manganese in the solution accounts for 49% to 68.6% of the total molar amount of metal elements; and / or,

[0027] The molar amount of the iron element in the solution accounts for 29.4%-49% of the total molar amount of the metal elements.

[0028] The present application controls the ambient temperature of the solution when it is added to the oxalic acid solution, thereby reducing side reactions and obtaining a precursor material with uniform composition, good batch consistency, and low impurity content.

[0029] The present application controls the time (rate) of adding the solution to the oxalic acid solution, thereby helping to control and reduce side reactions, and prepare a precursor material with uniform composition, good batch consistency, and low impurity content, thereby improving the electrical performance of the battery.

[0030] The present application controls the molar ratio of oxalic acid to total metal elements to influence the precipitation efficiency of metal ions, thereby improving the yield of preparing positive electrode materials, reducing raw material waste, and saving costs.

[0031] The present application can adjust the molar ratio of each metal element in the precursor product by controlling the concentration of each metal element in the solution.

[0032] In any embodiment, the pH-adjusted reaction product is aged before solid-liquid separation; and / or,

[0033] The aging temperature is 20°C-80°C; and / or,

[0034] The aging time is less than or equal to 3 hours, and can be selected from 0.2 to 3 hours.

[0035] Aging is beneficial to the crystallization and growth of the precipitate, so as to reduce the proportion of amorphous particles in the precursor material, thereby obtaining a precursor material with better crystallinity and higher compaction density, thereby improving the specific capacity of the battery.

[0036] In any embodiment, dissolving at 20°C-60°C; and / or,

[0037] The solvent is water; and / or,

[0038] The solid-liquid separation is filtration, which can be negative pressure filtration, positive pressure filtration or centrifugal filtration; and / or,

[0039] Before drying, washing the solid phase, optionally by washing the solid phase with water; and / or,

[0040] The drying temperature is 50°C-150°C; and / or,

[0041] The drying time is 120-240 minutes.

[0042] In any embodiment, the precursor material includes the compound Mn x Fe y M (1-x-y) C2O4·2H2O, wherein 0<x≤0.9, 0<y≤0.9, 0.9≤x+y<1, and M includes one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIII, and Group VIII.

[0043] In any embodiment, the pH value is adjusted using a pH adjuster;

[0044] Optionally, the pH regulator comprises a mixture of one or more of ammonia monohydrate solution, sodium hydroxide solution, potassium hydroxide solution, and lithium hydroxide solution; and / or the concentration of the pH regulator is 1-2 mol / L.

[0045] By adjusting the pH value to make the coprecipitation reaction more complete, the entry of cationic impurities into the reaction products is reduced, the purity and content stability of the precursor material are improved, and thus the specific capacity of the battery is improved.

[0046] In any embodiment, the soluble manganese source is a soluble manganese salt or a hydrate thereof, which may be selected from one or more of manganese sulfate, manganese nitrate, manganese chloride, manganese acetate or a hydrate thereof; and / or,

[0047] The soluble iron source is a soluble ferrous salt or a hydrate thereof, which can be selected from one or more of ferrous sulfate, ferrous nitrate, ferrous chloride, ferrous acetate or a hydrate thereof; and / or,

[0048] The source of the soluble M element is a salt of the soluble M element or a hydrate thereof, which may be one or more of sulfate, chloride, nitrate, organic acid salt of the M element or a hydrate thereof; and / or,

[0049] The M element includes one or more elements selected from titanium, vanadium, chromium, copper, magnesium, aluminum, zinc, cobalt, nickel, tin, niobium, tungsten, zirconium, tantalum, cerium, and europium.

[0050] The use of a soluble manganese source, a soluble iron source, and a soluble source of the M element is beneficial to reducing the impurity content in the precursor material, improving batch consistency, and thus improving the specific capacity and cycle performance of the battery.

[0051] The third aspect of the present application provides a positive electrode material, including a compound LiMn x Fe y M (1-x-y) PO4; wherein 0<x≤0.9, 0<y≤0.9, 0.9≤x+y<1, and M comprises one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIII, and Group VIII;

[0052] Furthermore, the raw materials for preparing the positive electrode material include the precursor material of the first aspect of the present application or the precursor material prepared by the method of the second aspect of the present application.

[0053] The fourth aspect of the present application provides a positive electrode material, comprising a core and a coating layer, wherein the core comprises a compound LiMn x Fe y M (1-x-y) PO4; wherein 0<x≤0.9, 0<y≤0.9, 0.9≤x+y<1, and M comprises one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIB, and Group VIII; and the coating layer comprises carbon;

[0054] Furthermore, the raw materials for preparing the positive electrode material include the precursor material of the first aspect of the present application or the precursor material prepared by the method of the second aspect of the present application.

[0055] Therefore, the molar ratio of manganese, iron and doping elements in the precursor material of the present application is the same as that in the positive electrode material, thereby reducing the types of raw materials when preparing the positive electrode material, improving the composition uniformity and batch consistency of the positive electrode material, and thus improving the specific capacity and cycle performance of the battery.

[0056] In any embodiment, 0.49≤x≤0.686; and / or,

[0057] 0.29≤y≤0.49; and / or,

[0058] 0.98≤x+y<1; and / or,

[0059] The M includes one or more elements selected from titanium, vanadium, chromium, copper, magnesium, aluminum, zinc, cobalt, nickel, tin, niobium, tungsten, zirconium, tantalum, cerium, and europium.

[0060] A fifth aspect of the present application provides a method for preparing a positive electrode material, comprising the following steps:

[0061] Mixing the precursor material of the first aspect of the present application or the precursor material prepared by the method of the second aspect of the present application, a lithium source, and a phosphorus source in a solvent, grinding, drying, and sintering to obtain a positive electrode material;

[0062] Wherein, the positive electrode material includes the compound LiMn x Fe y M (1-x-y) PO4; wherein, 0<x≤0.9, 0<y≤0.9, 0.9≤x+y<1, and M includes one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIB, and Group VIII.

[0063] A sixth aspect of the present application further provides a method for preparing a positive electrode material, comprising the following steps:

[0064] Mixing the precursor material of the first aspect of the present application or the precursor material prepared by the method of the second aspect of the present application, a lithium source, a phosphorus source, and a carbon source in a solvent, grinding, drying, and sintering to obtain a positive electrode material;

[0065] The positive electrode material includes a core and a coating layer, and the core includes a compound LiMn x Fe y M (1-x-y) PO4; wherein, 0<x≤0.9, 0<y≤0.9, 0.9≤x+y<1, and the M comprises one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIB, and Group VIII; and the coating layer comprises carbon.

[0066] Therefore, the molar ratio of manganese, iron and doping elements in the precursor material of the present application is the same as that in the positive electrode material. Therefore, when preparing the positive electrode material, it is only necessary to react the precursor material with a lithium source, a phosphorus source and an optional carbon source, thereby reducing the types of raw materials, improving the composition uniformity and batch consistency of the positive electrode material, and improving the specific capacity and cycle performance of the battery.

[0067] In any embodiment, the weight ratio of the precursor material to the lithium source is 6.5-8.5; and / or,

[0068] The molar ratio of the precursor material to the phosphorus source is 0.8-2.8; and / or

[0069] The molar ratio of the precursor material to the carbon source is 12.5-14.5; and / or

[0070] The insoluble matter in the mixture obtained after grinding has a Dv50 particle size of 0.1-2 μm; and / or,

[0071] The drying temperature is 80°C-150°C; and / or,

[0072] The drying time is 30-60 minutes; and / or,

[0073] The sintering temperature is 500° C.-800° C.; and / or,

[0074] The sintering time is 8-20h; and / or,

[0075] sintering under an inert atmosphere; and / or,

[0076] The M includes one or more elements selected from titanium, vanadium, chromium, copper, magnesium, aluminum, zinc, cobalt, nickel, tin, niobium, tungsten, zirconium, tantalum, cerium, and europium.

[0077] The insoluble matter in the mixture obtained after grinding reaches a certain Dv50 particle size, which is beneficial to increase the surface energy of the particles, improve the activity of the solid-solid reaction, shorten the diffusion path of lithium into the crystals of the precursor material, and make the reaction of generating the positive electrode material more complete, thereby improving the specific capacity of the battery.

[0078] The sintering temperature and sintering time adopted are conducive to making the reaction proceed more completely, thereby improving the electrical performance of the battery.

[0079] In a seventh aspect, the present application provides a positive electrode plate, comprising the positive electrode material of the third or fourth aspect of the present application or the positive electrode material prepared by the method of the fifth or sixth aspect of the present application.

[0080] The eighth aspect of the present application provides a battery, comprising the positive electrode plate of the seventh aspect of the present application.

[0081] The ninth aspect of the present application provides an electrical device comprising the battery of the eighth aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 Schematic diagram of a battery cell according to one embodiment of the present application.

[0083] Figure 2 yes Figure 1 FIG. 1 is an exploded view of a battery cell according to an embodiment of the present application.

[0084] Figure 3 Schematic diagram of a battery module according to one embodiment of the present application.

[0085] Figure 4 Schematic diagram of a battery pack according to one embodiment of the present application.

[0086] Figure 5 yes Figure 4 An exploded view of a battery pack according to an embodiment of the present application is shown.

[0087] Figure 6 FIG2 is a schematic diagram of an electrical device using a battery cell according to an embodiment of the present application as a power source.

[0088] Figure 7 This is a flow chart of the method for preparing the precursor materials of Examples 1-45 of the present application.

[0089] Figure 8 This is a scanning electron microscope photograph of the precursor material of Example 1 of the present application.

[0090] Description of reference numerals:

[0091] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery cell; 51 shell; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0092] Hereinafter, the precursor material, the method for preparing the precursor material, the method for preparing the positive electrode material, the positive electrode sheet, the negative electrode sheet, the battery cell, the battery module, the battery pack and the embodiment of the electric device of the present application will be described in detail with appropriate reference to the accompanying drawings. However, there will be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0093] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0094] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0095] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0096] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, a method includes steps (a) and (b), which indicates that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a method may further include step (c), which 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 may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0097] Unless otherwise specified, the Dv50 particle size in this application refers to the particle size when the cumulative value of volume distribution is 50%.

[0098] [Battery Cell]

[0099] A battery cell, also known as a rechargeable battery or storage battery, refers to a battery that can be recharged to activate the active material after discharge and continue to be used.

[0100] Typically, a battery cell consists of a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During the charge and discharge process of the battery, active ions (such as lithium ions) are embedded and released back and forth between the positive and negative electrode sheets. The separator is set between the positive and negative electrode sheets, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through. The electrolyte between the positive and negative electrode sheets mainly plays the role of conducting active ions.

[0101] [Precursor materials]

[0102] One embodiment of the present application provides a precursor material including a compound Mn x Fe y M (1-x-y) C2O4·2H2O; wherein 0<x≤0.9 (for example, x can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or a range consisting of any of the foregoing values), 0<y≤0.9 (for example, y can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or a range consisting of any of the foregoing values), 0.9≤x+y <1 (for example, x+y can be 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 0.998, 0.999, 0.999 or a range consisting of any of the foregoing values), and M includes one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIII, and Group VIII.

[0103] The conventional preparation method of element-doped lithium manganese iron phosphate positive electrode material is to prepare it by mechanically mixing multiple raw materials such as manganese source, iron source, lithium source, phosphorus source, and source of doping element, sand grinding to refine particles, spray drying, sintering and other processes; however, this method is prone to problems such as uneven composition, poor batch consistency and poor electrical performance.

[0104] Although the mechanism is still unclear, the applicant unexpectedly discovered that the manganese, iron, and doping elements in the precursor material of the present application are evenly distributed and have good batch consistency. The elements in the positive electrode material prepared using the precursor material of the present application are evenly distributed and have good batch consistency, thereby improving the specific capacity and cycle performance of the prepared battery.

[0105] In some embodiments, 0.49≤x≤0.686; and / or,

[0106] 0.29≤y≤0.49; and / or,

[0107] 0.98≤x+y<1; and / or,

[0108] The M includes one or more elements selected from titanium, vanadium, chromium, copper, magnesium, aluminum, zinc, cobalt, nickel, tin, niobium, tungsten, zirconium, tantalum, cerium, and europium, such as cobalt or nickel.

[0109] In some embodiments, the Dv50 particle size of the precursor material is 8-100 μm, optionally 12-85 μm, for example, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 25 μm, 30 μm, 36 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 64 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm or a range consisting of any of the above values.

[0110] The Dv50 particle size of the precursor material of the present application is within the above range, which is beneficial to the washing and filtering operations during the precursor preparation process on the one hand, and is beneficial to the suspension of the precursor particles and is not easy to settle when preparing the positive electrode material, thereby improving the efficiency of the mixing and grinding process.

[0111] In the present application, the Dv50 particle size can be measured by conventional methods in the art, such as taking a sample and adding deionized water to completely disperse the sample, and measuring the Dv50 particle size using a laser particle size analyzer (MasterSizer 2000).

[0112] In some embodiments, the precursor material has a compacted density of 1.1-3.0 g / cm at 30 MPa. 3 , optional 1.5-2.2g / cm 3 , for example 1.1 g / cm 3 , 1.3g / cm 3 , 1.5g / cm 3 , 1.6g / cm 3 , 1.7g / cm 3 , 1.8g / cm 3 , 1.9g / cm 3 , 2.0g / cm 3 , 2.1g / cm 3 , 2.2g / cm 3 , 2.5g / cm 3 , 2.7g / cm 3 , 2.8g / cm 3 , 3.0g / cm 3 Or any range consisting of the above values.

[0113] The compaction density of the precursor material of the present application is within the above range, which is beneficial to increasing the compaction density of the positive electrode material, thereby improving the specific capacity of the battery.

[0114] In this application, the compaction density can be measured by conventional methods in the field. For example, the sample is placed in the mold of a compaction density tester. The tester automatically applies a pressure of 30 MPa to the powder until the powder is compacted. According to the cross-sectional area of the mold and the thickness of the powder at this time, the volume of the powder can be calculated. According to compaction density = mass / volume, the compaction density of the powder material can be measured.

[0115] In some embodiments, the compound Mn in the precursor material x Fe y M (1-x-y) The weight content of C2O4·2H2O is 98.5%-99.98%, and can be optionally 98.6%-99.98%, for example, 98.5%, 98.6%, 98.8%, 99.0%, 99.1%, 99.3%, 99.5%, 99.6%, 99.7%, 99.8%, 99.85%, 99.9%, 99.95%, 99.98% or a range consisting of any of the above values.

[0116] The precursor material of the present application has a high compound content and a low impurity content, so the impurity content of the prepared positive electrode material is low and the specific capacity of the battery is improved.

[0117] [Method for preparing precursor material]

[0118] One embodiment of the present application provides a method for preparing a precursor material, comprising the following steps:

[0119] Dissolving a soluble manganese source, a soluble iron source, and a soluble source of an element M in a solvent to obtain a solution; wherein the element M comprises one or more metal elements from Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIII, and Group VIII;

[0120] adding the solution to an oxalic acid solution and reacting to obtain a reaction product;

[0121] The pH value of the reaction product is adjusted to 0.5-4 (optionally 1-4, such as 0.5, 1, 2, 3, 4 or a range consisting of any of the above values), solid-liquid separation is performed, and the solid phase is collected and dried to obtain a precursor material.

[0122] Thus, the method of the present application causes oxalate to coprecipitate with manganese ions, iron ions, and M element ions, thereby improving the uniformity of the distribution of each element in the material and batch consistency; by adjusting the pH value, the coprecipitation reaction is made more complete, thereby improving the product yield; and by controlling the addition sequence and adjusting the pH value, the entry of cationic impurities into the reaction product is reduced, thereby improving the purity and content stability of the precursor material; thereby improving the specific capacity and cycle performance of the battery.

[0123] In some embodiments, the solution is added to the oxalic acid solution and reacted at 15°C-95°C (optionally 20°C-90°C, such as 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or any range thereof); and / or,

[0124] The addition time of the solution is 5-300 min, optionally 10-300 min, for example, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, 90 min, 95 min, 100 min, 110 min, 130 min, 150 min, 170 min, 180 min, 190 min, 200 min, 220 min, 240 min, 250 min, 270 min, 280 min, 290 min, 300 min or a range consisting of any of the above values; and / or,

[0125] The molar ratio of oxalic acid in the oxalic acid solution to the total metal elements in the solution is 0.7-2, optionally 0.8-1.2, for example, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.7, 1.8, 1.9, 2.0 or any range thereof; and / or,

[0126] The total concentration of the metal elements in the solution is 1-3 mol / L, for example, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L or any range thereof; and / or,

[0127] The oxalic acid concentration in the oxalic acid solution is 1-3 mol / L, for example, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L or any range thereof; and / or,

[0128] The molar amount of manganese in the solution accounts for 49% to 68.6% of the total molar amount of metal elements, for example, 49%, 50%, 52%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 64%, 65%, 66%, 68%, 68.6% or any range thereof; and / or,

[0129] The molar amount of iron in the solution is 29.4%-49% of the total molar amount of metal elements, for example, 29.4%, 30%, 31%, 33%, 35%, 36%, 37%, 38%, 39%, 40%, 45%, 46%, 47%, 48%, 49% or a range consisting of any of the above values.

[0130] The present application controls the ambient temperature of the solution when it is added to the oxalic acid solution, thereby reducing side reactions and obtaining a precursor material with uniform composition, good batch consistency, and low impurity content.

[0131] The present application controls the time (rate) of adding the solution to the oxalic acid solution, thereby helping to control and reduce side reactions, and prepare a precursor material with uniform composition, good batch consistency, and low impurity content, thereby improving the electrical performance of the battery.

[0132] The present application improves the yield of preparing positive electrode materials and enhances the specific capacity of the battery by controlling the molar ratio of oxalic acid to total metal elements.

[0133] The present application can adjust the molar ratio of each metal element in the precursor product by controlling the concentration of each metal element in the solution.

[0134] In some embodiments, the pH-adjusted reaction product is aged before solid-liquid separation; and / or,

[0135] The aging temperature is 20°C-80°C, optionally 30°C-70°C, for example, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C or any range thereof; and / or,

[0136] The aging time is less than or equal to 3 hours, and can be 0.2-3 hours, and more preferably 0.5-2 hours, such as 0.1 hour, 0.2 hours, 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours or a range consisting of any of the above values.

[0137] Aging is beneficial to the crystallization and growth of the precipitate, so as to reduce the proportion of amorphous particles in the precursor material, thereby obtaining a precursor material with better crystallinity and higher compaction density, thereby improving the specific capacity of the battery.

[0138] In some embodiments, the solution is dissolved at 20°C-60°C (e.g., 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, or any range thereof); and / or,

[0139] The solvent is water; and / or,

[0140] The solid-liquid separation is filtration, which can be negative pressure filtration, positive pressure filtration or centrifugal filtration; and / or,

[0141] Before drying, washing the solid phase, optionally by washing the solid phase with water; and / or,

[0142] The drying temperature is 50°C-150°C, for example, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C or any range thereof; and / or,

[0143] The drying time is 120-240 min, for example, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, 180 min, 190 min, 200 min, 210 min, 220 min, 230 min, 240 min or a range consisting of any of the above values.

[0144] In some embodiments, the precursor material includes a compound Mn x Fe y M (1-x-y) C2O4·2H2O, wherein 0<x≤0.9 (for example, x can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or a range consisting of any of the foregoing values), 0<y≤0.9 (for example, y can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or a range consisting of any of the foregoing values), 0.9≤x+y <1 (for example, x+y can be 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 0.998, 0.999, 0.999 or a range consisting of any of the foregoing values), and M includes one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIII, and Group VIII.

[0145] In some embodiments, the precursor material is the aforementioned precursor material.

[0146] In some embodiments, the pH value is adjusted using a pH adjuster;

[0147] Optionally, the pH regulator comprises a mixture of one or more of ammonia monohydrate solution, sodium hydroxide solution, potassium hydroxide solution, and lithium hydroxide solution; and / or the concentration of the pH regulator is 1-2 mol / L.

[0148] By adjusting the pH value to make the coprecipitation reaction more complete, the entry of cationic impurities into the reaction products is reduced, the purity and content stability of the precursor material are improved, and thus the specific capacity of the battery is improved.

[0149] In some embodiments, the soluble manganese source is a soluble manganese salt or a hydrate thereof, which may be selected from one or more of manganese sulfate, manganese nitrate, manganese chloride, manganese acetate, or a hydrate thereof; and / or,

[0150] The soluble iron source is a soluble ferrous salt or a hydrate thereof, which can be selected from one or more of ferrous sulfate, ferrous nitrate, ferrous chloride, ferrous acetate or a hydrate thereof; and / or,

[0151] The source of the soluble M element is a salt of the soluble M element or a hydrate thereof, which may be one or more of sulfate, chloride, nitrate, organic acid salt of the M element or a hydrate thereof; and / or,

[0152] The M element includes one or more elements selected from titanium, vanadium, chromium, copper, magnesium, aluminum, zinc, cobalt, nickel, tin, niobium, tungsten, zirconium, tantalum, cerium, and europium.

[0153] The use of a soluble manganese source, a soluble iron source, and a soluble source of the M element is beneficial to reducing the impurity content in the precursor material, improving batch consistency, and thus improving the specific capacity and cycle performance of the battery.

[0154] [Cathode material]

[0155] One embodiment of the present application provides a positive electrode material including a compound LiMn x Fe y M (1-x-y) PO4; wherein, 0<x≤0.9 (for example, x can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or a range consisting of any of the above values), 0<y≤0.9 (for example, y can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or a range consisting of any of the above values), 0.9≤x+y<1( For example, x+y can be 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 0.998, 0.999, 0.999 or any range thereof), and M includes one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIII, and Group VIII;

[0156] Furthermore, the raw materials for preparing the positive electrode material include the aforementioned precursor material or the precursor material prepared by the aforementioned method.

[0157] Another embodiment of the present application provides a positive electrode material, including a core and a coating layer, wherein the core includes a compound LiMn x Fe y M (1-x-y) PO4; wherein, 0<x≤0.9 (for example, x can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or a range consisting of any of the above values), 0<y≤0.9 (for example, y can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or a range consisting of any of the above values), 0.9≤x+y<1 (for example, x+ y may be 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 0.998, 0.999, 0.999 or any range thereof), said M comprises one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIII, and Group VIII; said coating layer comprises carbon;

[0158] Furthermore, the raw materials for preparing the positive electrode material include the precursor material mentioned above in this application or the precursor material prepared by the method mentioned above in this application.

[0159] Therefore, the molar ratio of manganese, iron and doping elements in the precursor material of the present application is the same as that in the positive electrode material, thereby reducing the types of raw materials when preparing the positive electrode material, improving the composition uniformity and batch consistency of the positive electrode material, and thus improving the specific capacity and cycle performance of the battery.

[0160] In some embodiments, 0.49≤x≤0.686; and / or,

[0161] 0.29≤y≤0.49; and / or,

[0162] 0.98≤x+y<1; and / or,

[0163] The M includes one or more elements selected from titanium, vanadium, chromium, copper, magnesium, aluminum, zinc, cobalt, nickel, tin, niobium, tungsten, zirconium, tantalum, cerium, and europium.

[0164] [Method for preparing positive electrode material]

[0165] One embodiment of the present application provides a method for preparing a positive electrode material, comprising the following steps:

[0166] The precursor material described above in this application or the precursor material prepared by the method described above in this application, a lithium source, and a phosphorus source are mixed in a solvent, ground, dried, and sintered to obtain a positive electrode material;

[0167] Wherein, the positive electrode material includes the compound LiMn x Fe y M (1-x-y) PO4; wherein, 0<x≤0.9 (for example, x can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or a range consisting of any of the above values), 0<y≤0.9 (for example, y can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or a range consisting of any of the above values), 0.9≤x+y<1( For example, x+y can be 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 0.998, 0.999, 0.999 or a range consisting of any of the foregoing values), and M includes one or more metal elements from Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, and Group VIII.

[0168] Another embodiment of the present application provides a method for preparing a positive electrode material, comprising the following steps:

[0169] The precursor material described above in this application or the precursor material prepared by the method described above in this application, a lithium source, a phosphorus source, and a carbon source are mixed in a solvent, ground, dried, and sintered to obtain a positive electrode material;

[0170] The positive electrode material includes a core and a coating layer, and the core includes a compound LiMn x Fe y M (1-x-y) PO4; wherein, 0<x≤0.9 (for example, x can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or a range consisting of any of the above values), 0<y≤0.9 (for example, y can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or a range consisting of any of the above values), 0.9≤x+y<1 (for example, x+ y can be 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 0.998, 0.999, 0.999 or a range consisting of any of the foregoing values), the M includes one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIII, and Group VIII; and the coating layer includes carbon.

[0171] Therefore, the molar ratio of manganese, iron and doping elements in the precursor material of the present application is the same as that in the positive electrode material. Therefore, when preparing the positive electrode material, it is only necessary to react the precursor material with a lithium source, a phosphorus source and an optional carbon source, thereby reducing the types of raw materials, improving the composition uniformity and batch consistency of the positive electrode material, and improving the specific capacity and cycle performance of the battery.

[0172] In some embodiments, the weight ratio of the precursor material to the lithium source is 6.5-8.5, for example, 6.5, 6.7, 6.8, 7.0, 7.1, 7.3, 7.5, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5 or any range thereof; and / or,

[0173] The molar ratio of the precursor material to the phosphorus source is 0.8-2.8, for example, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.8, 1.9, 2.0, 2.1, 2.2, 2.2, 2.5, 2.6, 2.7, 2.8 or any range thereof; and / or

[0174] The molar ratio of the precursor material to the carbon source is 12.5-14.5, for example, 12.5, 12.6, 12.7, 12.8, 13.0, 13.1, 13.2, 13.3, 13.5, 13.6, 13.7, 13.8, 13.9, 14.0, 14.1, 14.2, 14.3, 14.4, 14.5 or any range thereof; and / or

[0175] The Dv50 particle size of the insoluble matter in the mixture obtained after grinding is 0.1-2 μm, optionally 0.2-1 μm, for example 0.1 μm, 0.2 μm, 0.3 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.3 μm, 1.5 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm or a range consisting of any of the above values; and / or,

[0176] The drying temperature is 80°C-150°C, for example, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C or any range thereof; and / or,

[0177] The drying time is 30-60 min, for example, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min or any range thereof; and / or,

[0178] The sintering temperature is 500° C.-800° C., for example, 500° C., 550° C., 600° C., 650° C., 700° C., 750° C., 800° C. or any range thereof; and / or,

[0179] The sintering time is 8-20 hours, for example, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours or any range thereof; and / or,

[0180] sintering under an inert atmosphere; and / or,

[0181] The M includes one or more elements selected from titanium, vanadium, chromium, copper, magnesium, aluminum, zinc, cobalt, nickel, tin, niobium, tungsten, zirconium, tantalum, cerium, and europium.

[0182] The insoluble matter in the mixture obtained after grinding reaches a certain Dv50 particle size, which is beneficial to increase the surface energy of the particles, improve the activity of the solid-solid reaction, shorten the diffusion path of lithium into the crystals of the precursor material, and make the reaction of generating the positive electrode material more complete, thereby improving the specific capacity of the battery.

[0183] The sintering temperature and sintering time adopted are conducive to making the reaction proceed more completely, thereby improving the electrical performance of the battery.

[0184] [Positive electrode]

[0185] The positive electrode sheet generally includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes a positive electrode material.

[0186] The battery's charge and discharge processes involve the intercalation and deintercalation of lithium, leading to different molar Li contents at different discharge states. The molar Li contents listed in this application for cathode materials refer to the initial state of the material, i.e., the state before addition of the materials. When the cathode material is used in a battery system, the molar Li content will change after charge and discharge cycles.

[0187] In the list of positive electrode materials in this application, the molar content of O is only a theoretical value. Lattice oxygen release will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0188] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0189] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0190] In some embodiments, the positive electrode material includes the aforementioned positive electrode material or the positive electrode material prepared by the aforementioned method.

[0191] In some embodiments, the positive electrode material may also include positive electrode materials for batteries that are well known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium transition metal oxides and modified compounds thereof. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. Among them, examples of lithium transition metal oxides may include but are not limited to lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and at least one of its modified compounds, etc.

[0192] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0193] In some embodiments, the positive electrode film layer may further include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0194] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0195] [Negative electrode]

[0196] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0197] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0198] 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 base layer and a metal layer formed on at least one surface of the polymer base material. 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 base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0199] In some embodiments, the negative electrode active material may be a negative electrode active material for a battery that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0200] In some embodiments, the negative electrode film layer may further include a binder. For example, 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).

[0201] In some embodiments, the negative electrode film layer may further include a conductive agent. For example, 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.

[0202] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0203] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0204] [Electrolytes]

[0205] The electrolyte conducts ions between the positive and negative electrodes. This application does not specify the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0206] In some embodiments, the electrolyte is liquid and includes an electrolyte salt and a solvent.

[0207] 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 difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0208] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0209] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0210] [Isolation film]

[0211] In some embodiments, the battery cell further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0212] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven 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.

[0213] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0214] In some embodiments, the battery cell may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0215] In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the battery cell may be a soft shell, such as a pouch-type soft shell. The soft shell may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0216] The present application has no particular restrictions on the shape of the battery cell, which can be cylindrical, square or any other shape. For example, Figure 1 The battery cell 5 is a square structure as an example.

[0217] In some embodiments, reference Figure 2 , the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0218] In some embodiments, battery cells may be assembled into a battery module. The battery module may contain one or more battery cells. The specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0219] Figure 3 4 is an example of a battery module. Figure 3 In the battery module 4, the plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. The plurality of battery cells 5 may further be fixed by fasteners.

[0220] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0221] In some embodiments, the battery modules described above may be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0222] Figure 4 and Figure 5 The battery pack 1 is used as an example. Figure 4 and Figure 5 The battery pack 1 may include a battery box and multiple battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner in the battery box.

[0223] In addition, the present application also provides an electrical device, which includes at least one of the battery cells, battery modules, or battery packs provided in the present application. The battery cells, battery modules, or battery packs can be used as power sources for the electrical device, or as energy storage units for the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto.

[0224] As an electrical device, a battery cell, battery module or battery pack can be selected according to its usage requirements.

[0225] Figure 6 This is an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the battery cells in this device, a battery pack or battery module can be used.

[0226] [Example]

[0227] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0228] Example 1

[0229] (1) Preparation of precursor materials (such as Figure 7 shown):

[0230] According to the molar ratio of Mn, Fe and Co elements of 6:4:0.2, 7.36 mol MnSO4·H2O (purity ≥99 wt%), 4.91 mol FeSO4·7H2O (purity ≥99 wt%) and 0.25 mol CoSO4·7H2O (purity ≥99 wt%) were weighed into a stirring tank, and pure water was added to make the volume to 5000 mL. The stirring function and the water bath heating function were turned on. After the liquid was heated to 55°C, the metal salt was completely dissolved, and the metal salt solution was obtained and kept warm for later use.

[0231] According to the above-mentioned total metal ion to oxalic acid molar ratio of 1:1.05, weigh 12.88 mol of H2C2O4·2H2O (product content ≥99%) into a stirring tank, add pure water to 5000 mL, stir evenly, and turn on the water bath heating function to heat the liquid to 55°C to obtain an oxalic acid solution for use.

[0232] Keep the water bath temperature at 55°C. Under stirring conditions, slowly and evenly add the above metal salt solution to the oxalic acid solution through a peristaltic pump to mix and react. The flow rate of the metal salt solution is about 150 mL min -1 It takes about 25 minutes to add all the liquid, and stirring is continued for 10 minutes after adding.

[0233] Continue to add ammonia water (concentration of 2 mol / L) to the obtained material using a peristaltic pump until the pH value is adjusted to 3.0; maintain the water bath temperature at 55°C, continue stirring and ageing for 30 minutes to ensure sufficient reaction and complete precipitation to obtain a slurry.

[0234] The slurry was transferred to a vacuum filtration device with a maximum vacuum pressure of -0.06 MPa, and the filter cake was collected by filtration; 5 L of pure water was added to wash the filter cake 2-3 times to obtain a precursor filter cake; the precursor filter cake was transferred to a blast drying oven, the drying temperature was set to 105 ° C, and dried for 3 hours. At this time, the material was basically constant weight, and the precursor material was obtained.

[0235] (2) Preparation of positive electrode materials:

[0236] Weigh 795.00 g of precursor material, 109.75 g of lithium carbonate, 511.00 g of phosphoric acid (concentration 85 weight%), and 60.00 g of glucose, add them to 1428.57 g of pure water, mix evenly, put them into a ball mill and grind them to a particle size Dv50 of 0.8 μm to obtain a slurry; dry the slurry for 60 min at a drying temperature of 100°C to obtain a powder; use an atmosphere box furnace to sinter the powder at 700°C for 12 h in a nitrogen atmosphere to obtain a positive electrode material.

[0237] (3) Preparation of positive electrode sheet:

[0238] Using an analytical balance (accuracy 0.0001g), weigh 0.3000g of polyvinylidene fluoride (PVDF) binder in 10.8g of N-methylpyrrolidone (NMP) and stir until completely dissolved. Then, add 2.4000g of the aforementioned positive electrode material and 0.3000g of carbon black conductive agent (SP) and stir until a paste is formed. The paste is evenly coated onto aluminum foil using an applicator and dried in a vacuum oven to remove the NMP solvent. After rolling and punching, a 16.0mm diameter disc is obtained to serve as the positive electrode sheet.

[0239] (4) Negative electrode: Metal lithium sheet is used.

[0240] (5) Isolation film: PE-PP composite film.

[0241] (6) Preparation of electrolyte:

[0242] Ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed in a volume ratio of 1:1, and then LiPF6 was uniformly dissolved in the above solution to obtain an electrolyte solution. The concentration of LiPF6 in the electrolyte solution was 1 mol / L.

[0243] (7) Preparation of button cells:

[0244] The positive electrode sheet, separator, negative electrode sheet and electrolyte were assembled into a CR2032 button battery.

[0245] The secondary battery preparation methods of Example 2-45 and Comparative Example 1-2 are similar to those of Example 1, but the parameters are adjusted. The different parameters are detailed in Table 1-3.

[0246] Comparative Example 1

[0247] (1) According to the molar ratio of Li:Mn:Fe:Co:PO4 of 10.2:6:4:0.2:10.2, 109.75g of lithium carbonate and 511g of 85wt% phosphoric acid solution were first added to 5945.63g of pure water for mixed reaction to obtain lithium dihydrogen phosphate solution, and then 7.36mol of MnC2O4·2H2O, 4.91mol of FeC2O4·2H2O, 0.25mol of CoC2O4·7H2O, and 60g of glucose were added and mixed uniformly. The mixture was placed in a ball mill and ground to a particle size Dv50 of 0.8μm to obtain a slurry; the slurry was dried for 60min at a drying temperature of 100℃ to obtain a powder; and the powder was sintered at 700℃ for 12h in an atmosphere box furnace under a nitrogen atmosphere to obtain a positive electrode material.

[0248] Steps (2)-(6) are the same as steps (3)-(7) of Example 1.

[0249]

[0250]

[0251]

[0252]

[0253]

[0254]

[0255]

[0256] Material testing and battery testing

[0257] (1) Chemical formula test of precursor and cathode material and compound content test in precursor:

[0258] Weigh 0.2 g of precursor material or cathode material into a 100 mL beaker, add 10 mL of 10% w / w nitric acid solution, heat and digest at 120°C for 0.5 hours, and then dilute to volume with a 100 mL volumetric flask; then use a pipette to transfer 1 mL to a 100 mL volumetric flask and dilute to volume to obtain the test solution.

[0259] The mass fractions of lithium, manganese, iron, phosphorus, and doping elements in the test solution were determined by inductively coupled plasma optical emission spectrometry (ICP-OES, instrument brand: Agilent 5800). The mass fraction of oxalate in the test solution was determined by titration using a 0.06 mol / L potassium permanganate solution as the titrant. The molar ratio of each element in the precursor material or cathode material was calculated based on the mass fraction of each element to determine the chemical formula.

[0260] The mass fraction of the Mn element in the above-mentioned test solution is measured by titration, and the titrant is 0.1 mol / L ammonium ferrous sulfate solution. The mass fraction of the Mn element in the precursor material is then calculated. Combined with the chemical formula, the mass content of the compound in the precursor material is calculated.

[0261] (2) Dv50 particle size test:

[0262] Take an appropriate amount of sample, add 20 mL of deionized water, and ultrasonically treat for 5 minutes (53 KHz, 120 W) to completely disperse the sample. Use a laser particle size analyzer (MasterSizer 2000) to measure the Dv50 particle size of the material.

[0263] (3) Compaction density test:

[0264] Weigh 0.6000g of precursor material and place it in the compaction density tester mold. The tester automatically applies 30MPa of pressure to the powder until the powder is compacted. The volume of the powder can be calculated based on the cross-sectional area of the mold and the thickness of the powder at this time. According to the compaction density = mass / volume, the compaction density of the powder material can be measured.

[0265] (4) Calculation of yield: Yield = 100% × actual product mass / theoretical product mass

[0266] (5) Micromorphology evaluation:

[0267] The microscopic crystal morphology of the precursor material of Example 1 was observed using a scanning electron microscope (SEM, instrument brand: ZEISS sigma 300).

[0268] like Figure 8 As shown, the precursor material is a secondary particle formed by the agglomeration of primary particles, and the primary particles present an irregular flaky structure.

[0269] (6) Test of discharge specific capacity and cycle capacity retention rate

[0270] The button cells were subjected to 50 cycle charge and discharge tests using a Shenzhen Xinweier battery testing system at charge and discharge rates of 0.1C, 0.3C, and 1.0C, respectively. The test temperature was 25.0°C, and the charge and discharge voltage range was 2.0V to 4.3V. The discharge specific capacity was calculated by dividing the initial discharge capacity at a charge and discharge rate of 0.1C, 0.3C, or 1.0C by the mass of the positive electrode material on the electrode sheet. The cycle capacity retention was calculated by dividing the 50th discharge capacity at a charge and discharge rate of 0.1C, 0.3C, or 1.0C by the initial discharge capacity.

[0271] Table 4: Performance test results of Examples 1-45 and Comparative Examples 1-2

[0272]

[0273]

[0274] According to the above results, we can know that:

[0275] Compared with Comparative Example 1 in which the positive electrode material is prepared by a conventional method, the battery discharge specific capacity of Examples 1-18, 20-28, and 33-45 of the present application is higher.

[0276] Compared with the comparative example 2 in which a higher manganese content is used when preparing the precursor, the batteries of Examples 1-18, 20-29, and 33-45 of the present application have a higher discharge specific capacity and a higher cycle capacity retention rate.

[0277] Compared with the longer or shorter aging time and lower or higher compaction density of the precursors prepared in Examples 33-34, the discharge specific capacity of the batteries in Examples 1, 4-5, and 15-16 of the present application is higher.

[0278] Compared with the faster solution addition rate when preparing the precursor in Example 37, the discharge specific capacity of the batteries in Examples 1, 6-7, and 10-11 of the present application is higher.

[0279] Compared with Examples 39-40, which use a lower or higher molar ratio of oxalic acid to the total amount of metal elements when preparing the precursor, Examples 1-3 and 12-13 of the present application have a higher yield for preparing the positive electrode material, reduce raw material waste, and save costs.

[0280] Compared with the use of a lower pH value when preparing the precursor in Example 41, the yield of the positive electrode material prepared in Examples 1-3 and 14 of the present application is higher and the discharge specific capacity of the prepared batteries is higher.

[0281] Compared with the use of lower or higher aging temperatures when preparing the precursors in Examples 42-43, the discharge specific capacity of the batteries in Examples 1-3 and 15-16 of the present application is higher.

[0282] Compared with the larger or smaller Dv50 particle size of the insoluble matter after grinding when preparing the positive electrode material in Examples 44-45, the discharge specific capacity of the batteries in Examples 1-3 and 26-27 of the present application is higher.

[0283] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A precursor material comprising a compound Mn x Fe y M (1-x-y) C2O4·2H2O; among which, 0 <x≤0.9, 0<y≤0.9, 0.9≤x+y<1, and M includes one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, and Group VIII.

2. The precursor material according to claim 1, wherein 0.49≤x≤0.686; and / or, 0.29≤y≤0.49; and / or, 0.98≤x+y<1; and / or, The M includes one or more elements selected from titanium, vanadium, chromium, copper, magnesium, aluminum, zinc, cobalt, nickel, tin, niobium, tungsten, zirconium, tantalum, cerium, and europium.

3. The precursor material according to claim 1 or 2, wherein The Dv50 particle size of the precursor material is 8-100 μm; and / or, The precursor material has a compaction density of 1.1-3.0 g / cm at 30 MPa. 3 and / or, The compound Mn in the precursor material x Fe y M (1-x-y) The weight content of C2O4·2H2O is 98.5%-99.98%.

4. A method for preparing a precursor material, comprising the following steps: A soluble manganese source, a soluble iron source and a soluble source of M element are dissolved in a solvent to obtain a solution; wherein, The M element includes one or more metal elements from Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIB, and Group VIII; adding the solution to an oxalic acid solution and reacting to obtain a reaction product; The pH value of the reaction product is adjusted to 0.5-4, the solid-liquid separation is carried out, and the solid phase is collected and dried to obtain a precursor material.

5. The method according to claim 4, wherein adding the solution to an oxalic acid solution at 15° C. to 95° C. and reacting; and / or, The solution is added for 5-300 min; and / or, The molar ratio of oxalic acid in the oxalic acid solution to the total amount of metal elements in the solution is 0.7-2; and / or, The total concentration of metal elements in the solution is 1-3 mol / L; and / or, The oxalic acid concentration in the oxalic acid solution is 1-3 mol / L; and / or, The molar amount of manganese in the solution accounts for 49% to 68.6% of the total molar amount of metal elements; and / or, The molar amount of the iron element in the solution accounts for 29.4%-49% of the total molar amount of the metal elements.

6. The method according to claim 4 or 5, wherein: Before solid-liquid separation, the pH-adjusted reaction product is aged; and / or, The aging temperature is 20°C-80°C; and / or, The aging time is less than or equal to 3 hours.

7. The method according to any one of claims 4 to 6, wherein dissolves at 20°C-60°C; and / or, The solvent is water; and / or, The solid-liquid separation is filtration, which can be negative pressure filtration, positive pressure filtration or centrifugal filtration; and / or, Before drying, washing the solid phase, optionally with water; and / or, The drying temperature is 50°C-150°C; and / or, The drying time is 120-240 minutes.

8. The method according to any one of claims 4 to 7, wherein The precursor material includes compound Mn x Fe y M (1-x-y) C2O4·2H2O, wherein 0<x≤0.9, 0<y≤0.9, 0.9≤x+y<1, and M includes one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIII, and Group VIII.

9. The method according to any one of claims 4 to 8, wherein A pH adjuster was used to adjust the pH value.

10. The method according to any one of claims 4 to 9, wherein The soluble manganese source is a soluble manganese salt or a hydrate thereof; and / or, The soluble iron source is a soluble ferrous salt or a hydrate thereof; and / or, The source of the soluble M element is a salt of the soluble M element or a hydrate thereof; and / or, The M element includes one or more elements selected from titanium, vanadium, chromium, copper, magnesium, aluminum, zinc, cobalt, nickel, tin, niobium, tungsten, zirconium, tantalum, cerium, and europium.

11. A positive electrode material comprising a compound LiMn x Fe y M (1-x-y) PO4; where 0 <x≤0.9, 0<y≤0.9, 0.9≤x+y<1, wherein M comprises one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIII, and Group VIII; Furthermore, the raw material for preparing the positive electrode material includes the precursor material according to any one of claims 1 to 3 or the precursor material prepared by the method according to any one of claims 4 to 10.

12. A positive electrode material comprising a core and a coating layer, wherein the core comprises a compound LiMn x Fe y M (1-x-y) PO4; where 0 <x≤0.9, 0<y≤0.9, 0.9≤x+y<1, the M comprises one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIII, and Group VIII; the coating layer comprises carbon; Furthermore, the raw material for preparing the positive electrode material includes the precursor material according to any one of claims 1 to 3 or the precursor material prepared by the method according to any one of claims 4 to 10.

13. The positive electrode material according to claim 11 or 12, wherein 0.49≤x≤0.686; and / or, 0.29≤y≤0.49; and / or, 0.98≤x+y<1; and / or, The M includes one or more elements selected from titanium, vanadium, chromium, copper, magnesium, aluminum, zinc, cobalt, nickel, tin, niobium, tungsten, zirconium, tantalum, cerium, and europium.

14. A method for preparing a positive electrode material, comprising the following steps: Mixing the precursor material according to any one of claims 1 to 3 or the precursor material prepared by the method according to any one of claims 4 to 10, a lithium source, and a phosphorus source in a solvent, grinding, drying, and sintering to obtain a positive electrode material; in, The positive electrode material includes the compound LiMn x Fe y M (1-x-y) PO4; Among them, 0<x≤0.9, 0<y≤0.9, 0.9≤x+y<1, and the M includes one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIII, and Group VIII.

15. A method for preparing a positive electrode material, comprising the following steps: Mixing the precursor material according to any one of claims 1 to 3 or the precursor material prepared by the method according to any one of claims 4 to 10, a lithium source, a phosphorus source, and a carbon source in a solvent, grinding, drying, and sintering to obtain a positive electrode material; in, The positive electrode material includes a core and a coating layer, and the core includes a compound LiMn x Fe y M (1-x-y) PO4; Wherein, 0<x≤0.9, 0<y≤0.9, 0.9≤x+y<1, the M includes one or more metal elements of Group IIA, Group IIIA, Group IVA, Group IB, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, Group VIB, and Group VIII; the coating layer includes carbon.

16. The method according to claim 14 or 15, wherein: The weight ratio of the precursor material to the lithium source is 6.5-8.5; and / or, The molar ratio of the precursor material to the phosphorus source is 0.8-2.8; and / or The molar ratio of the precursor material to the carbon source is 12.5-14.5; and / or The insoluble matter in the mixture obtained after grinding has a Dv50 particle size of 0.1-2 μm; and / or, The drying temperature is 80°C-150°C; and / or, The drying time is 30-60 minutes; and / or, The sintering temperature is 500° C.-800° C.; and / or, The sintering time is 8-20h; and / or, sintering under an inert atmosphere; and / or, The M includes one or more elements selected from titanium, vanadium, chromium, copper, magnesium, aluminum, zinc, cobalt, nickel, tin, niobium, tungsten, zirconium, tantalum, cerium, and europium.

17. A positive electrode sheet, comprising the positive electrode material according to any one of claims 11 to 13 or the positive electrode material prepared by the method according to any one of claims 14 to 16. A battery comprising the positive electrode sheet according to claim 17 .

19. An electrical device comprising the battery according to claim 18.

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