Lithium manganese iron phosphate positive electrode material and preparation method thereof, lithium ion battery and electrical equipment

Abstract

The present application provides a lithium iron manganese phosphate positive electrode material and its preparation method, lithium ion battery and electrical equipment, which relate to the field of new energy technology. The lithium iron manganese phosphate positive electrode material provided by the present application uses an amorphous precursor and a high crystalline precursor as raw materials. The high crystalline precursor leads to a higher specific surface area of ​​the material, which affects the processing performance; the amorphous precursor can improve the compaction density and specific surface area of ​​the material. By combining the two precursors, the capacity and cycle performance of the lithium iron manganese phosphate positive electrode material are guaranteed. The combination of elements with different valence states plays the role of doping and coating at the same time, synergistically improving the performance of the material; elements with lower valence states are easily doped in the lithium iron manganese phosphate crystal structure to increase the capacity of the material; elements with higher valence states are distributed on the surface of the lithium iron manganese phosphate particles to improve the stability of the surface structure of the material.

Description

Technical Field

[0001] The present application relates to the field of new energy technology, and in particular to a lithium iron manganese phosphate positive electrode material and a preparation method thereof, a lithium-ion battery and electrical equipment. Background Art

[0002] Lithium iron manganese phosphate and lithium iron phosphate have similar theoretical discharge specific capacities, but the voltage platform of lithium iron manganese phosphate is significantly higher than that of lithium iron phosphate, which offers the advantage of high energy density in the power sector. However, lithium iron manganese phosphate has a low compaction density and poor conductivity. The Jahn-Teller effect during charge and discharge can easily lead to manganese dissolution and unstable crystal structure, resulting in poor cycling performance. Summary of the Invention

[0003] The purpose of this application is to provide a lithium iron manganese phosphate positive electrode material and its preparation method, a lithium ion battery and electrical equipment, aiming to solve the problems of low compaction density, poor conductivity and poor cycle performance of existing lithium iron manganese phosphate.

[0004] To achieve the above objectives, the present application provides a lithium manganese iron phosphate cathode material, comprising a base material and a composite coating layer; wherein,

[0005] The matrix material comprises a positive electrode material A made from a precursor A and a positive electrode material B made from a precursor B;

[0006] The precursor A is an amorphous precursor with (Fe+Mn) / P=0.960~0.975, and the precursor B is a highly crystalline precursor with (Fe+Mn) / P=0.970~0.985;

[0007] The chemical formulas of the positive electrode material A and the positive electrode material B are independently Li a [Fe x Mn 1-x ] 1-y M y PO4, wherein a is 1.01 to 1.05; 0.1≤x≤0.6, preferably 0.2≤x≤0.5; 0.01≤y≤0.08, preferably 0.015≤y≤0.07, more preferably 0.02≤y≤0.06, and M includes Mg 2+ 、Ni 2+ 、Co 3+ 、V 3+ 、Ti 4+ At least one of, preferably including Mg 2+ 、Ti 4+ At least one of the positive electrode material A and the positive electrode material B may have the same or different chemical formulas;

[0008] The composite coating layer includes carbon and M' oxide, wherein M' includes Zr 4+ 、Ti 4+ 、Nb 5+ 、W 6+ 、Mo 6+ At least one of, preferably including Nb 5+ 、Ti 4+ At least one of .

[0009] In some embodiments, the mass of the carbon is 1.0-2.0% of the total mass of the matrix material.

[0010] In some embodiments, the M includes divalent elements, trivalent elements, and tetravalent elements with lower valences, and the M′ includes tetravalent elements, pentavalent elements, and hexavalent elements with higher valences.

[0011] Preferably, the M and M' are Mg 2+ and Nb 5+ , or Ti 4+ and Nb 5+ , or Mg 2+ and Ti 4+ , or Mg 2+ and Zr 4+ , or V 3+ and W 6+ , or Mg 2+ and Ti 4+ and Nb 5+ , or (Mg 2+ and Ti 4+ ) and (Nb 5+ and Ti 4+ ), more preferably, Mg 2+ and Nb 5+ .

[0012] In some embodiments, at least one of the following conditions is met:

[0013] A. In the X-ray diffraction pattern of the lithium manganese iron phosphate positive electrode material, the diffraction peak within the diffraction angle 2θ range of 32.0°-34.0° is the (131) diffraction peak, and the peak intensity of the (131) diffraction peak is I （131） 3300-4300, preferably 3400-3600;

[0014] B. The specific surface area of ​​the lithium manganese iron phosphate positive electrode material is 5-30g / m 2 , preferably 10-20g / m 2 , more preferably 11-17g / m 2 ;

[0015] C. The compaction density of the lithium manganese iron phosphate positive electrode material is 2.3-2.55 g / cm 3 , preferably 2.35-2.5 g / cm 3 ;

[0016] D. The resistivity of the lithium manganese iron phosphate positive electrode material is 5-50Ω·cm, preferably 8-14Ω·cm;

[0017] E. The thickness of the composite coating layer is 1-50 nm, preferably 3-20 nm.

[0018] The present application also provides a method for preparing a lithium manganese iron phosphate positive electrode material, comprising:

[0019] (1) Precursor A, precursor B, lithium source, carbon source, dopant, coating agent and water are mixed uniformly to obtain a mixture.

[0020] The chemical formula of the precursor A is (Fe x’ Mn (1-x’) ) 0.960-0.975 PO4,

[0021] The chemical formula of the precursor B is (Fe x’’ Mn (1-x’’) ) 0.970~0.985 PO4,

[0022] Wherein, 0.1≤x'≤0.6, preferably 0.2≤x'≤0.5, 0.1≤x''≤0.6, preferably 0.2≤x''≤0.5, x' and x'' may be the same or different;

[0023] (2) wet-grinding the mixture to obtain a slurry, and spray-drying the slurry to obtain a dry material;

[0024] (3) sintering and crushing the dried material to obtain an intermediate material;

[0025] (4) The intermediate material is subjected to secondary sintering in an atmosphere containing a gaseous carbon source to obtain the lithium manganese iron phosphate positive electrode material.

[0026] In some embodiments, the mass ratio of the precursor A to the precursor B is (10:90) to (40:60).

[0027] In some embodiments, at least one of the following conditions is met:

[0028] (1) The molar ratio of lithium in the lithium source to the total metal elements of the precursor A and the precursor B satisfies Li / (Fe+Mn)=1.01-1.05, and / or the lithium source comprises at least one of lithium carbonate and lithium hydroxide;

[0029] (2) The carbon source is 9%-15% of the total mass of the precursor A and the precursor B, and / or the carbon source includes at least one of glucose, sucrose, polyethylene glycol, and polyvinyl alcohol;

[0030] (3) The dopant comprises at least one of magnesium oxide, magnesium hydroxide, magnesium nitrate, nickel oxide, nickel hydroxide, nickel nitrate, cobalt oxide, cobalt hydroxide, cobalt nitrate, vanadium pentoxide, ammonium metavanadate, titanium dioxide, and metatitanic acid;

[0031] and / or the molar amount of the doping element M of the dopant is 0.01 to 0.08, preferably 0.02 to 0.06, of the sum of the molar amount of the total metal elements in the precursor A and the precursor B and the molar amount of the doping element M;

[0032] (4) The coating agent comprises at least one of zirconium oxide, titanium dioxide, metatitanic acid, niobium pentoxide, niobic acid, tungsten trioxide, and molybdenum trioxide;

[0033] The molar amount of the coating element M' of the coating agent is 0.01 to 0.06 of the sum of the molar amount of the total metal elements of the precursor A and the precursor B and the molar amount of the coating element M'.

[0034] In some embodiments, the primary sintering temperature is 550-850° C. and the time is 4-10 hours;

[0035] And / or, the secondary sintering temperature is 500-800° C. and the time is 2-6 hours;

[0036] and / or, in step (1), adjusting the solid content to 30% to 45% by using water;

[0037] And / or, in the wet sand milling, the sand milling particle size D50 is controlled to be 0.2-0.5 μm, preferably 0.35-0.40 μm;

[0038] And / or, the inlet air temperature of the spray drying is 220-280°C, and the outlet air temperature is 90-120°C;

[0039] And / or, the pulverization is air flow pulverization, and the final air powder particle size meets the following requirements: D10 ≥ 0.20 μm, D50 is 0.3-1.1 μm, preferably 0.4-0.6 μm, D90 ≤ 10 μm, and 1.0 ≤ (D90-D10) / D50 ≤ 3.0;

[0040] and / or, the gaseous carbon source comprises at least one of methane, ethane, ethylene, and acetylene;

[0041] And / or, the flow rate of the gaseous carbon source is 0.1-0.6 L / min, preferably 0.2-0.5 L / min.

[0042] The present application also provides a lithium-ion battery, the raw materials of which include the above-mentioned lithium iron manganese phosphate positive electrode material, or the lithium iron manganese phosphate positive electrode material prepared by the above-mentioned method.

[0043] The present application also provides an electrical device comprising the above-mentioned lithium-ion battery.

[0044] Compared with the prior art, the advantages of this application include:

[0045] The lithium iron manganese phosphate positive electrode material provided in this application uses two different types of iron manganese phosphate precursors as raw materials. The amorphous precursor is a block particle formed by the accumulation of blocky primary particles. The amorphous precursor has a low dehydration and sintering temperature, a small specific surface area BET, basically no pores, is difficult to grind, and has a low (Fe+Mn) / P ratio. The particle size of the finally formed lithium iron manganese phosphate positive electrode material is larger, which improves the processing performance.

[0046] Highly crystalline precursors are blocky particles formed by the accumulation of flaky primary particles. They undergo long aging times and require high dehydration and sintering temperatures. They exhibit high crystallinity, high specific surface area, and distinct crystallization peaks, which facilitate the diffusion of doping elements and lithium ions in the resulting lithium iron manganese phosphate cathode material, thereby increasing capacity. Highly crystalline precursors have a large BET specific surface area, large cross-sectional pores, and are easy to grind. They also have a high (Fe+Mn) / P ratio, resulting in a smaller particle size for the resulting lithium iron manganese phosphate cathode material.

[0047] Highly crystalline precursors may lead to a higher specific surface area of ​​the material, thereby affecting the processing performance; amorphous precursors can improve the material's compaction density and specific surface area and other properties. By combining the two precursors, it is possible to ensure the capacity of the lithium manganese iron phosphate positive electrode material and improve the cycle performance, and to exert a beneficial synergistic effect, so that the lithium manganese iron phosphate positive electrode material can obtain both high electrochemical performance and good processing performance.

[0048] Based on the use of the above two different types of manganese iron phosphate precursors as raw materials, the manganese iron phosphate lithium positive electrode material of the present application can improve the capacity of the material and the cycle performance by further including specific lower valence elements in the doping elements and specific higher valence elements in the coating elements, thereby ultimately playing a synergistic role in significantly improving the material performance.

[0049] Specifically, the reactivity of the doping elements with lower valence states is higher, and they are easily doped into the crystal structure of lithium iron manganese phosphate. They can improve the electrochemical properties of the material and increase the capacity of the material while changing the crystal structure. The reactivity of the coating elements with higher valence states is lower, and they are difficult to be doped into the interior of the lithium iron manganese phosphate particles. They are easily distributed on the surface of the lithium iron manganese phosphate particles, which can improve the stability of the surface structure of the material, thereby improving the cycle performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0051] Figure 1 XRD patterns of the amorphous precursor and the highly crystalline precursor used in this application;

[0052] Figure 2 SEM image of the amorphous precursor used in this application;

[0053] Figure 3 This is a SEM image of the highly crystalline precursor used in this application;

[0054] Figure 4 This is an SEM image of the lithium manganese iron phosphate positive electrode material of Example 1;

[0055] Figure 5 This is an XPS graph of the surface of the lithium manganese iron phosphate positive electrode material of Example 1;

[0056] Figure 6 This is the XRD pattern of the lithium manganese iron phosphate positive electrode material of Example 1;

[0057] Figure 7 This is the charge and discharge curve of the lithium manganese iron phosphate positive electrode material of Example 1;

[0058] Figure 8 This is the charge and discharge curve of the lithium manganese iron phosphate positive electrode material of Comparative Example 1. DETAILED DESCRIPTION

[0059] As used herein:

[0060] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0061] The conjunction "consisting of" excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed, excluding materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim, rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0062] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0063] In these examples, parts and percentages are by mass unless otherwise indicated.

[0064] "Parts by mass" refers to the basic unit of measurement used to express the mass ratio of multiple components. One part can represent any unit of mass, such as 1g or 2.689g. For example, if we say that the parts by mass of component A are a parts and the parts by mass of component B are b parts, this means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, we could say that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number representing a multiplication factor). It's important to note that, unlike parts by mass, the sum of the parts by mass of all components is not limited to 131 parts.

[0065] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0066] The present application provides a lithium manganese iron phosphate positive electrode material, comprising a base material and a composite coating layer; wherein,

[0067] The matrix material comprises a positive electrode material A made from a precursor A and a positive electrode material B made from a precursor B;

[0068] The precursor A is an amorphous precursor with (Fe+Mn) / P=0.960~0.975, and the precursor B is a highly crystalline precursor with (Fe+Mn) / P=0.970~0.985;

[0069] The chemical formulas of the positive electrode material A and the positive electrode material B are independently Li a [Fe x Mn 1-x ] 1-y M y PO4, wherein a is 1.01 to 1.05; 0.1≤x≤0.6, preferably 0.2≤x≤0.5; 0.01≤y≤0.08, preferably 0.015≤y≤0.07, more preferably 0.02≤y≤0.06, and M includes Mg 2+ 、Ni 2+ 、Co 3+ 、V 3+ 、Ti 4+ At least one of, preferably including Mg 2+ 、Ti 4+ At least one of, more preferably including Mg 2+ , the chemical formulas of the positive electrode material A and the positive electrode material B may be the same or different;

[0070] The composite coating layer includes carbon and M' oxide, wherein M' includes Zr 4+ 、Ti 4+ 、Nb 5+ 、W 6+ 、Mo 6+ At least one of, preferably including Nb 5+ 、Ti 4+ At least one of, more preferably including Nb 5+ .

[0071] Among them, the amorphous precursor is a blocky particle formed by the accumulation of blocky primary particles, and its specific surface area BET is relatively small, which is 3-7m 2 / g, basically no pores, difficult to grind, and low (Fe+Mn) / P, relatively large particles, D50 is 6~9μm, the dehydration sintering temperature of the amorphous precursor is low, with low crystallinity characteristics, and no obvious crystallization peak in XRD.

[0072] The highly crystalline precursor is a block of particles formed by the accumulation of flaky primary particles, with a large specific surface area BET of 6-12m 2 / g, the cross-section pores are large, easy to grind, and the (Fe+Mn) / P is high. The particles are relatively small, with a D50 of 3~8μm. Most of the small particles in the finished product come from high-crystalline precursors; the high-crystalline precursors have a long aging time and a high dehydration and sintering temperature, forming high crystallinity and high specific surface area characteristics, with obvious crystallization peaks, which are more conducive to the diffusion of doping elements and lithium ions, and facilitate capacity utilization.

[0073] The (Fe+Mn) / P ratio of the amorphous precursor may be, for example, 0.960, 0.965, 0.970, 0.975, or any value between 0.960 and 0.975. The (Fe+Mn) / P ratio of the highly crystalline precursor may be, for example, 0.970, 0.975, 0.980, 0.985, or any value between 0.970 and 0.985.

[0074] In some embodiments, the mass of the carbon is 1.0% to 2.0% of the total mass of the matrix material, for example, it can be 1.0%, 1.5%, 2.0%, or any value between 1.0% and 2.0%.

[0075] In some embodiments, the M includes divalent elements, trivalent elements, and tetravalent elements with lower valence, and the M' includes tetravalent elements, pentavalent elements, and hexavalent elements with higher valence;

[0076] Preferably, the M and M' are Mg 2+ and Nb 5+ , or Ti 4+ and Nb 5+ , or Mg 2+ and Ti 4+ , or Mg 2+ and Zr 4+ , or V 3+ and W 6+ , or Mg 2+ and Ti 4+ and Nb 5+ , or (Mg 2+ and Ti 4+ ) and (Nb 5+ and Ti 4+ ), more preferably, Mg 2+ and Nb 5+ .

[0077] M includes a lower valence element, and M' includes a higher valence element; by including a specific lower valence element in the doping element and a specific higher valence element in the cladding element, a synergistic effect is achieved.

[0078] The valence states of the lower valence elements are divalent, trivalent and tetravalent, and the valence states of the higher valence elements are tetravalent, pentavalent and hexavalent.

[0079] Ti 4+ It can be used as both a doping element and a coating element, mainly due to its dosage. 4+ When the doping molar amount is less than or equal to 0.02, the XPS results show that there is no characteristic peak of Ti element on the surface of the material, indicating that Ti 4+ When Ti is fully doped into the internal grains of the material, 4+When the doping molar amount is higher than or equal to 0.03, the XPS results show that a Ti peak appears on the surface of the material. 4+ It not only enters the material as a part of the doping element, but also covers the surface of the material as a part of the coating element.

[0080] In some embodiments, in the X-ray diffraction pattern of the lithium manganese iron phosphate positive electrode material, the diffraction peak in the diffraction angle 2θ range of 32.0°-34.0° is the (131) diffraction peak, and the peak intensity I of the (131) diffraction peak is （131） The molecular weight of the present invention is 3300-4300, for example, it can be 3300, 3400, 3500, 3600, 3700, 3800, 3900, 4000, 4100, 4200, 4300 or any value between 3300-4300, preferably 3400-3600.

[0081] In some embodiments, the specific surface area of ​​the lithium manganese iron phosphate positive electrode material is 5-30 g / m 2 , for example, it can be 5g / m 2 , 10g / m 2 , 15g / m 2 , 20g / m 2 , 25g / m 2 , 30g / m 2 or 5-30g / m 2 Any value between 10-20 g / m 2 , more preferably 11-17g / m 2 .

[0082] In some embodiments, the compaction density of the lithium manganese iron phosphate positive electrode material is 2.3-2.55 g / cm 3 , for example, it can be 2.3g / cm 3 , 2.35g / cm 3 , 2.4g / cm 3 , 2.45g / cm 3 , 2.5g / cm 3 , 2.55g / cm 3 or 2.3-2.55g / cm 3 Any value between 2.35-2.5 g / cm 3 .

[0083] In some embodiments, the resistivity of the lithium iron manganese phosphate positive electrode material is 5-50Ω·cm, for example, it can be 5Ω·cm, 10Ω·cm, 15Ω·cm, 20Ω·cm, 25Ω·cm, 30Ω·cm, 35Ω·cm, 40Ω·cm, 45Ω·cm, 50Ω·cm or any value between 5-50Ω·cm, preferably 8-14Ω·cm.

[0084] In some embodiments, the thickness of the composite coating layer is 1-50 nm, for example, it can be 1 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm or any value between 1-50 nm, preferably 3-20 nm.

[0085] The present application also provides a method for preparing a lithium manganese iron phosphate positive electrode material, comprising:

[0086] (1) Precursor A, precursor B, lithium source, carbon source, dopant, coating agent and water are mixed uniformly to obtain a mixture.

[0087] The chemical formula of the precursor A is (Fe x’ Mn (1-x’) ) 0.960-0.975 PO4,

[0088] The chemical formula of the precursor B is (Fe x’’ Mn (1-x’’) ) 0.970~0.985 PO4,

[0089] Wherein, 0.1≤x'≤0.6, preferably 0.2≤x'≤0.5, 0.1≤x''≤0.6, preferably 0.2≤x''≤0.5, x' and x'' may be the same or different;

[0090] (2) wet-grinding the mixture to obtain a slurry, and spray-drying the slurry to obtain a dry material;

[0091] (3) sintering and crushing the dried material to obtain an intermediate material;

[0092] (4) The intermediate material is subjected to secondary sintering in an atmosphere containing a gaseous carbon source to obtain the lithium manganese iron phosphate positive electrode material.

[0093] The carbon source in step (1) is used for reduction and coating, and the gaseous carbon source in step (4) is used for further coating.

[0094] In some embodiments, the mass ratio of the precursor A to the precursor B is (10:90) to (40:60), for example, it can be 10:90, 20:80, 30:70 or 40:60.

[0095] In some embodiments, the molar ratio of the lithium of the lithium source to the total metal elements of the precursor A and the precursor B satisfies Li / (Fe+Mn)=1.01~1.05, for example, it can be 1.01, 1.02, 1.03, 1.04, 1.05 or any value between 1.01~1.05, and / or, the lithium source comprises at least one of lithium carbonate and lithium hydroxide.

[0096] In some embodiments, the carbon source is 9%-15% of the total mass of the precursor A and the precursor B, for example, it can be 9%, 10%, 11%, 12%, 13%, 14%, 15% or any value between 9% and 15%, and / or, the carbon source includes at least one of glucose, sucrose, polyethylene glycol, and polyvinyl alcohol.

[0097] In some embodiments, the dopant comprises at least one of magnesium oxide, magnesium hydroxide, magnesium nitrate, nickel oxide, nickel hydroxide, nickel nitrate, cobalt oxide, cobalt hydroxide, cobalt nitrate, vanadium pentoxide, ammonium metavanadate, titanium dioxide, and metatitanic acid.

[0098] And / or, the molar amount of the doping element M of the dopant is 0.01 to 0.08 of the sum of the molar amount of the total metal elements of the precursor A and the precursor B and the molar amount of the doping element M, for example, it can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08 or any value between 0.01 and 0.08, preferably 0.02 to 0.06.

[0099] In some embodiments, the coating agent comprises at least one of zirconium oxide, titanium dioxide, metatitanic acid, niobium pentoxide, niobic acid, tungsten trioxide, and molybdenum trioxide;

[0100] The molar amount of the coating element M' of the coating agent is 0.01-0.06 of the sum of the molar amount of the total metal elements of the precursor A and the precursor B and the molar amount of the coating element M', for example, it can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06 or any value between 0.01 and 0.06.

[0101] In some embodiments, the primary sintering temperature is 550-850°C, for example, it can be 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C or any value between 550-850°C, and the time is 4-10h, for example, it can be 4h, 6h, 8h, 10h or any value between 4-10h.

[0102] In some embodiments, the secondary sintering temperature is 500~800℃, for example, it can be 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃ or any value between 500 and 800℃, and the time is 2 to 6h, for example, it can be 2h, 4h, 6h or any value between 2 and 6h.

[0103] In some embodiments, water is used in step (1) to adjust the solid content to 30% to 45%, for example, 30%, 35%, 40%, 45% or any value between 30% and 45%.

[0104] In some embodiments, during the wet sanding, the sanding particle size D50 is controlled to be 0.2-0.5 μm, for example, it can be 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm or any value between 0.2-0.5 μm, preferably 0.35-0.4 μm.

[0105] In some embodiments, the inlet air temperature of the spray drying is 220-280°C, for example, it can be 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C or any value between 220 and 280°C, and the outlet air temperature is 90-120°C, for example, it can be 90°C, 100°C, 110°C, 120°C or any value between 90 and 120°C.

[0106] In some embodiments, the pulverization is air flow pulverization, and the final air powder particle size satisfies: D10 ≥ 0.20 um, D50 is 0.3-1.1 um, preferably 0.4-0.6 um, D90 ≤ 10 um, 1.0 ≤ (D90-D10) / D50 ≤ 3.0.

[0107] In some embodiments, the gaseous carbon source includes at least one of methane, ethane, ethylene, and acetylene.

[0108] In some embodiments, the flow rate of the gaseous carbon source is 0.1-0.6 L / min, for example, it can be 0.1 L / min, 0.2 L / min, 0.3 L / min, 0.4 L / min, 0.5 L / min, 0.6 L / min or any value between 0.1-0.6 L / min, preferably 0.2-0.5 L / min.

[0109] The present application also provides a lithium-ion battery, the raw materials of which include the above-mentioned lithium iron manganese phosphate positive electrode material, or the lithium iron manganese phosphate positive electrode material prepared by the above-mentioned method.

[0110] The present application also provides an electrical device comprising the above-mentioned lithium-ion battery.

[0111] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, the conditions are carried out according to conventional conditions or manufacturer recommendations. The reagents or instruments used are not specified by the manufacturer and are conventional products that can be purchased commercially.

[0112] The amorphous precursor A (Fe 0.4 Mn 0.6 ) 0.965 PO4, high crystalline precursor B (Fe 0.4 Mn 0.6 ) 0.975 XRD of PO4 Figure 1 As shown, the degree of crystallinity of the characteristic peaks is obviously different. The SEM images of the amorphous precursor are shown in Figure 2 As shown, the SEM image of the highly crystalline precursor is Figure 3 All shown were purchased from Hubei Gaobo Technology Co., Ltd.

[0113] Example 1

[0114] This embodiment provides a lithium manganese iron phosphate positive electrode material, and the preparation method thereof includes the following steps:

[0115] (1) The amorphous precursor A (Fe 0.4 Mn 0.6 ) 0.965 PO4, high crystalline precursor B (Fe 0.4 Mn 0.6 ) 0.975 PO4, lithium carbonate as a lithium source, glucose as a carbon source, magnesium oxide as a dopant, niobic acid as a coating agent, and pure water are uniformly mixed to obtain a mixture;

[0116] The mass ratio of precursor A to precursor B is 20:80, and the specific surface area of ​​precursor A is 5 m 2 / g, the particle size D50 is 7 μm; the specific surface area of ​​precursor B is 9 m 2 / g, particle size D50 is 5μm; the molar ratio of lithium element in lithium carbonate to the total metal elements of precursor A and precursor B satisfies Li / (Fe+Mn)=1.02; the mass ratio of glucose to the total mass of the precursor is 12%; the molar amount of Mg in magnesium oxide is 0.04 of (the molar amount of the total metal elements in the precursor + the molar amount of Mg), and the molar amount of Nb in the coating agent niobic acid is 0.03 of (the molar amount of the total metal elements in the precursor + the molar amount of Nb); the solid content of the mixture is 40%;

[0117] (2) wet-grinding the mixture to obtain a slurry, and spray-drying the slurry to obtain a dry material;

[0118] The final particle size D50 of the sand mill was 0.37 μm; the inlet air temperature of the spray drying was 240°C and the outlet air temperature was 110°C;

[0119] (3) The dried material was sintered at 600 °C for 8 h and then subjected to air flow milling. The final D50 was 0.5 μm, (D90-D10) / D50=2.0, and the intermediate material was obtained.

[0120] (4) The intermediate material is secondary sintered at 700°C for 3 hours in a methane atmosphere with a gas flow rate of 0.4 L / min to obtain a lithium manganese iron phosphate positive electrode material, which includes a base material and a composite coating layer. The chemical composition of the base material is Li 1.02 (Fe 0 .4 Mn 0.6 ) 0.96 Mg 0.04 PO4.

[0121] The lithium manganese iron phosphate cathode material prepared in Example 1 was characterized by SEM. The results are as follows Figure 4 As shown in the figure, the material contains large and small particles, and the particle surface is relatively smooth and the carbon coating is relatively uniform. Figure 5 This is the XPS characterization of the surface of the material obtained in Example 1. The surface of the material shows obvious characteristic peaks of Nb, indicating that Nb is coated on the surface of the material. Figure 6 The XRD of the material obtained in Example 1 shows the characteristic peaks of conventional lithium manganese iron phosphate material; the diffraction peak with a diffraction angle 2θ of 33.2° is the (131) diffraction peak, and the peak intensity of the (131) diffraction peak is 3500.

[0122] The particle size D50 of the lithium manganese iron phosphate positive electrode material prepared in Example 1 is 0.5 μm, the carbon content is 1.6 wt% of the total mass of the base material, the thickness of the composite coating layer is 7 nm, and the specific surface area is 12.5 g / m 2 ; The strongest peak I in XRD （131） The unit is 3500 (atomic units), and the compacted density is 2.45 g / cm 3 , resistivity is 9.8 Ω·cm; 0.1C discharge capacity is 155.4 mAh / g, 1C discharge capacity is 147.4 mAh / g, the first efficiency is 97.6%, and the capacity after 50 cycles at 1C is 146.6 mAh / g.

[0123] Example 2

[0124] This embodiment provides a lithium manganese iron phosphate positive electrode material, and its preparation method differs from that of Example 1 in that:

[0125] (1) The mass ratio of precursor A to precursor B is 40:60, the molar ratio of lithium element in lithium carbonate to the total metal elements of precursor A and precursor B satisfies Li / (Fe+Mn)=1.05; the mass ratio of glucose to the total mass of the precursor is 15%; the molar amount of Mg in magnesium oxide is 0.06 of (the molar amount of the total metal elements of the precursor + the molar amount of Mg), and the molar amount of Nb in the coating agent niobic acid is 0.06 of (the molar amount of the total metal elements of the precursor + the molar amount of Nb); the solid content is 40%;

[0126] (2) The final particle size D50 of sand grinding is 0.40 μm; the inlet air temperature of spray drying is 280 °C and the outlet air temperature is 120 °C;

[0127] (3) The dried material was sintered at 850 °C for 4 h and then subjected to air flow milling. The final D50 was 1.1 μm, (D90-D10) / D50=2.2, and the intermediate material was obtained.

[0128] (4) The intermediate material is secondary sintered at 800°C for 2 hours in a methane atmosphere with a gas flow rate of 0.5 L / min to obtain a lithium manganese iron phosphate positive electrode material, which includes a base material and a composite coating layer. The chemical composition of the base material is Li 1.05 (Fe 0 .4 Mn 0.6 ) 0.94 Mg 0.06 PO4.

[0129] Example 3

[0130] This embodiment provides a lithium manganese iron phosphate positive electrode material, and its preparation method differs from that of Example 1 in that:

[0131] (1) The mass ratio of precursor A to precursor B is 10:90; the molar ratio of lithium element in lithium carbonate to the total metal elements of precursor A and precursor B satisfies Li / (Fe+Mn)=1.01; the mass ratio of glucose to the total mass of the precursor is 9%; the molar amount of Mg in magnesium oxide is 0.02 of (the molar amount of the total metal elements of the precursor + the molar amount of Mg), and the molar amount of Nb in the coating agent niobic acid is 0.01 of (the molar amount of the total metal elements of the precursor + the molar amount of Nb);

[0132] (2) The final particle size D50 of sand grinding is 0.35 μm; the inlet air temperature of spray drying is 220 °C and the outlet air temperature is 90 °C;

[0133] (3) The dried material was sintered at 550 °C for 10 h and then subjected to air flow milling. The final D50 was 0.3 μm, (D90-D10) / D50=1.5, and the intermediate material was obtained.

[0134] (4) The intermediate material is secondary sintered in a methane atmosphere at 500°C for 6 hours with a gas flow rate of 0.2 L / min to obtain a lithium manganese iron phosphate positive electrode material, which includes a base material and a composite coating layer. The chemical composition of the base material is Li 1.01 (Fe 0 .4 Mn 0.6 ) 0.98 Mg 0.02 PO4.

[0135] Example 4

[0136] This embodiment provides a lithium manganese iron phosphate positive electrode material, and its preparation method differs from that of Example 1 in that:

[0137] The chemical formula of amorphous precursor A is (Fe 0.5 Mn 0.5 ) 0.960 PO4 (purchased from Hubei Gaobo Technology Co., Ltd.), the chemical formula of the highly crystalline precursor B is (Fe 0.5 Mn 0.5 ) 0.970 PO4 (purchased from Hubei Gaobo Technology Co., Ltd.), and other steps were the same as in Example 1.

[0138] Example 5

[0139] This embodiment provides a lithium manganese iron phosphate positive electrode material, and its preparation method differs from that of Example 1 in that:

[0140] The chemical formula of amorphous precursor A is (Fe 0.2 Mn 0.8 ) 0.975 PO4 (purchased from Hubei Gaobo Technology Co., Ltd.), the chemical formula of the highly crystalline precursor B is (Fe 0.2 Mn 0.8 ) 0.985 PO4 (purchased from Hubei Gaobo Technology Co., Ltd.), and other steps were the same as in Example 1.

[0141] Example 6

[0142] This embodiment provides a lithium manganese iron phosphate positive electrode material, and its preparation method differs from that of Example 1 in that:

[0143] The dopant is titanium dioxide, and the molar amount of Ti is 0.04 of (the molar amount of the total metal elements in the precursor + the molar amount of Ti). Other than this, the other steps are the same as those in Example 1.

[0144] After testing, it was found that when the molar amount of the dopant titanium dioxide was 0.04, the main part of the titanium element was doped into the matrix material, and a small part of the titanium element was coated on the surface of the material, thereby containing Ti and Nb in the coating layer.

[0145] Example 7

[0146] This embodiment provides a lithium manganese iron phosphate positive electrode material, and its preparation method differs from that of Example 1 in that:

[0147] The dopants are magnesium oxide and titanium dioxide, the molar amount of Mg and Ti is 0.04 of (the molar amount of the total metal elements of the precursor + the molar amount of Mg and Ti), and the molar ratio of Mg to Ti is 1:1. Other than that, the same as in Example 1.

[0148] Comparative Example 1

[0149] This comparative example provides a lithium manganese iron phosphate positive electrode material, and its preparation method differs from that of Example 1 in that:

[0150] The amorphous precursor A (Fe 0.4 Mn 0.6 ) 0.965 PO4 was changed to a corresponding amount of high crystalline precursor B (Fe 0.4 Mn 0.6 ) 0.975 Except for PO4, the others are the same as those in Example 1.

[0151] Comparative Example 2

[0152] This comparative example provides a lithium manganese iron phosphate positive electrode material, and its preparation method differs from that of Example 1 in that:

[0153] The highly crystalline precursor B (Fe 0.4 Mn 0.6 ) 0.975 PO4 was changed to the corresponding amount of amorphous precursor A (Fe 0.4 Mn 0.6 ) 0.965 Except for PO4, the others are the same as those in Example 1.

[0154] Comparative Example 3

[0155] This comparative example provides a lithium manganese iron phosphate positive electrode material, and its preparation method differs from that of Example 1 in that:

[0156] The process was the same as in Example 1 except that magnesium oxide as a dopant was changed to tungsten oxide as a coating agent and the molar amount of W was 0.04 of (the molar amount of the total metal elements in the precursor + the molar amounts of W and Nb).

[0157] Comparative Example 4

[0158] This comparative example provides a lithium manganese iron phosphate positive electrode material, and its preparation method differs from that of Example 1 in that:

[0159] The process was the same as in Example 1 except that niobic acid as a coating agent was replaced with aluminum oxide as a dopant, and the molar amount of Al in the aluminum oxide was 0.03 of (the molar amount of the total metal elements in the precursor + the molar amounts of Mg and Al).

[0160] The physical indicators of the lithium manganese iron phosphate positive electrode materials of each embodiment and comparative example are shown in Table 1. The compaction density is measured using a Sansi Zongheng battery powder compaction density meter, and the resistivity is measured using an instrument manufactured by Yuanneng Technology Co., Ltd.

[0161] Table 1 Physical indicators of lithium manganese iron phosphate positive electrode materials of various embodiments and comparative examples

[0162]

[0163] Power-off test process

[0164] The positive electrode materials prepared in the Examples and Comparative Examples were mixed with PVDF and NMP in a ratio of 90:5:5 to prepare a positive electrode slurry. This slurry was then coated onto aluminum foil, dried, and then punched and sheared to produce positive electrode sheets. Button cells were assembled in a glove box by combining the positive electrode sheets with the lithium sheet, separator, and electrolyte. The assembled button cells were placed in the mold of a hydraulic sealing machine, locked, and pressurized. The seal was then released, and the sealed button cells were removed. The separator was Celgard polypropylene film, and the electrolyte was purchased from Xinya Shanshan New Materials Technology Co., Ltd.

[0165] The test was performed using a Lanhe (model: CT3002A) battery test cabinet with a test voltage range of 2.0V to 4.5V. Specifically, the battery was charged to 4.5V at a constant current of 0.1C, charged to 50μA at a constant voltage, and discharged to 2.0V at 0.1C. This was considered the first cycle, and the discharge capacity after the first cycle was recorded as the 0.1C discharge capacity (mAh / g).

[0166] Again, charge at a constant current of 1C to 4.5V, charge at a constant voltage of 50μA, and discharge at 1C to 2.0V. Record the discharge capacity after the second cycle as the 1C discharge capacity (mAh / g).

[0167] Again, continue to charge at a constant current of 1C to 4.5V, charge at a constant voltage to 50μA, and discharge at 1C to 2.0V. Repeat the above operation and record the discharge capacity after the 51st cycle as the 1C discharge capacity (mAh / g) after 50 cycles.

[0168] The charge and discharge curves of the lithium manganese iron phosphate positive electrode material of Example 1 are as follows: Figure 7 As shown, the charge and discharge curve of the lithium manganese iron phosphate positive electrode material of Comparative Example 1 is as follows Figure 8 The electrochemical properties of the lithium manganese iron phosphate positive electrode materials of the embodiments and comparative examples are shown in Table 2.

[0169] Table 2 Electrochemical properties of lithium manganese iron phosphate cathode materials of various examples and comparative examples

[0170]

[0171] From the data tables obtained from Examples 1-7 and Comparative Examples 1-4, it can be seen that the capacity and first efficiency of the lithium manganese iron phosphate positive electrode material obtained by the present application solution are better than those obtained by the comparative example solution, among which the lithium manganese iron phosphate positive electrode material obtained in Example 1 has the best electrochemical performance. Compared with Examples 1-7, Comparative Examples 1-4 all showed poor performance. Among them, Comparative Example 1 only used highly crystalline precursor B, and the specific surface area of ​​the obtained positive electrode material was higher. Although the capacity was not much different from that of the embodiment, the cycle performance was poor; Comparative Example 2 only used amorphous precursor A, and the specific surface area of ​​the obtained positive electrode material was smaller and the capacity was lower; in Comparative Example 3, magnesium oxide as a dopant was changed to tungsten oxide as a coating agent. Due to the high-valent element W 6+ It cannot enter the positive electrode material grains and cannot dope the material. Therefore, the lithium manganese iron phosphate positive electrode material obtained in Comparative Example 3 only has the coating element and is not doped with the specific lower valence element of the present invention, which affects the electrochemical properties such as the discharge capacity of the positive electrode material. In Comparative Example 4, niobate as a coating agent is changed to aluminum oxide as a dopant. Since Al 3+ As a low-valent element, it is easy to enter the interior of the material for doping. Therefore, the coating layer does not contain the specific higher-valent elements of the present invention, resulting in poor stability of the material surface structure and failure to play a synergistic role in improving material properties.

[0172] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

[0173] Furthermore, those skilled in the art will appreciate that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and to form distinct embodiments. For example, in the claims above, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is intended solely to enhance understanding of the overall background of this application and should not be construed as an admission or any implication that such information constitutes prior art known to those skilled in the art.

Claims

1. A lithium manganese iron phosphate positive electrode material, characterized in that: It includes a base material and a composite coating layer, wherein: The matrix material comprises a positive electrode material A made from a precursor A and a positive electrode material B made from a precursor B; The precursor A is an amorphous precursor with (Fe+Mn) / P=0.960~0.975, and the precursor B is a highly crystalline precursor with (Fe+Mn) / P=0.970~0.985; the chemical formula of the precursor A is (Fe x’ Mn (1-x’) ) 0.960-0.975 PO4, the chemical formula of the precursor B is (Fe x’’ Mn (1-x’’) ) 0.970~0.985 PO4, where 0.1≤x'≤0.6, 0.1≤x''≤0.6, and x' and x'' may be the same or different; The chemical formulas of the positive electrode material A and the positive electrode material B are independently Li a [Fe x Mn 1-x ] 1-y M y PO4, wherein a is 1.01-1.05; 0.1≤x≤0.6; 0.01≤y≤0.08, and M includes divalent elements, trivalent elements, and tetravalent elements with lower valence states, and M includes Mg 2+ 、Ni 2+ 、Co 3+ 、V 3+ 、Ti 4+ At least one of the positive electrode material A and the positive electrode material B may have the same or different chemical formulas; The composite coating layer includes carbon and M' oxides, wherein M' includes tetravalent elements, pentavalent elements and hexavalent elements with higher valences, wherein M' includes Zr 4+ 、Ti 4+ 、Nb 5+ 、W 6+ 、Mo 6+ At least one of; The preparation method of the lithium manganese iron phosphate positive electrode material comprises: mixing precursor A, precursor B, a lithium source, a carbon source, a dopant containing M, a coating agent containing M' and water, drying, and sintering to obtain the lithium manganese iron phosphate positive electrode material.

2. The lithium manganese iron phosphate positive electrode material according to claim 1, characterized in that At least one of the following conditions is met: A. The mass of the carbon is 1.0% to 2.0% of the total mass of the matrix material; B. In the chemical formula of the positive electrode material A and the positive electrode material B, 0.2≤x≤0.5; C. In the chemical formulas of the positive electrode material A and the positive electrode material B, 0.015≤y≤0.07; D. The M includes Mg 2+ 、Ti 4+ At least one of; E. The M' includes Nb 5+ 、Ti 4+ At least one of .

3. The lithium manganese iron phosphate positive electrode material according to claim 1, characterized in that The M and the M' are Mg 2+ and Nb 5+ , or Ti 4+ and Nb 5+ , or Mg 2+ and Ti 4+ , or Mg 2+ and Zr 4+ , or V 3+ and W 6+ , or Mg 2+ and Ti 4+ and Nb 5+ .

4. The lithium manganese iron phosphate positive electrode material according to any one of claims 1 to 3, characterized in that At least one of the following conditions is met: A. In the X-ray diffraction pattern of the lithium manganese iron phosphate positive electrode material, the diffraction peak within the diffraction angle 2θ range of 32.0°-34.0° is the (131) diffraction peak, and the peak intensity of the (131) diffraction peak is I （131） 3300-4300; B. The specific surface area of ​​the lithium manganese iron phosphate positive electrode material is 5-30g / m 2 ; C. The compaction density of the lithium manganese iron phosphate positive electrode material is 2.3-2.55 g / cm 3 ; D. The resistivity of the lithium manganese iron phosphate positive electrode material is 5-50Ω·cm; E. The D50 of the lithium manganese iron phosphate positive electrode material is 0.3-1.1 um; F. The thickness of the composite coating layer is 1-50 nm.

5. The lithium manganese iron phosphate positive electrode material according to claim 4, characterized in that At least one of the following conditions is met: A. Peak intensity of the (131) diffraction peak I （131） 3400-3600; B. The specific surface area of ​​the lithium manganese iron phosphate positive electrode material is 10-20 g / m 2 ; C. The compaction density of the lithium manganese iron phosphate positive electrode material is 2.35-2.5 g / cm 3 ; D. The resistivity of the lithium manganese iron phosphate positive electrode material is 8-14Ω·cm; E. The D50 of the lithium manganese iron phosphate positive electrode material is 0.4-0.6 um; F. The thickness of the composite coating layer is 3-20 nm.

6. A method for preparing the lithium manganese iron phosphate positive electrode material according to any one of claims 1 to 5, characterized in that: include: (1) Precursor A, precursor B, lithium source, carbon source, dopant, coating agent and water are mixed uniformly to obtain a mixture. The chemical formula of the precursor A is (Fe x’ Mn (1-x’) ) 0.960-0.975 PO4, The chemical formula of the precursor B is (Fe x’’ Mn (1-x’’) ) 0.970~0.985 PO4, Among them, 0.1≤x'≤0.6, 0.1≤x''≤0.6, x' and x'' can be the same or different; (2) wet-grinding the mixture to obtain a slurry, and spray-drying the slurry to obtain a dry material; (3) sintering and crushing the dried material to obtain an intermediate material; (4) The intermediate material is subjected to secondary sintering in an atmosphere containing a gaseous carbon source to obtain the lithium manganese iron phosphate positive electrode material.

7. The method for preparing the lithium manganese iron phosphate positive electrode material according to claim 6, characterized in that: The mass ratio of the precursor A to the precursor B is (10:90) to (40:60).

8. The method for preparing the lithium manganese iron phosphate positive electrode material according to claim 6 or 7, characterized in that: At least one of the following conditions is met: (1) The molar ratio of lithium in the lithium source to the total metal elements of the precursor A and the precursor B satisfies Li / (Fe+Mn)=1.01-1.05, and / or the lithium source comprises at least one of lithium carbonate and lithium hydroxide; (2) The carbon source is 9%-15% of the total mass of the precursor A and the precursor B, and / or the carbon source includes at least one of glucose, sucrose, polyethylene glycol, and polyvinyl alcohol; (3) The dopant comprises at least one of magnesium oxide, magnesium hydroxide, magnesium nitrate, nickel oxide, nickel hydroxide, nickel nitrate, cobalt oxide, cobalt hydroxide, cobalt nitrate, vanadium pentoxide, ammonium metavanadate, titanium dioxide, and metatitanic acid; and / or, the molar amount of the doping element M of the dopant is 0.01 to 0.08 of the sum of the molar amount of the total metal elements in the precursor A and the precursor B and the molar amount of the doping element M; (4) The coating agent comprises at least one of zirconium oxide, titanium dioxide, metatitanic acid, niobium pentoxide, niobic acid, tungsten trioxide, and molybdenum trioxide; The molar amount of the coating element M' of the coating agent is 0.01 to 0.06 of the sum of the molar amount of the total metal elements of the precursor A and the precursor B and the molar amount of the coating element M'.

9. The method for preparing the lithium manganese iron phosphate positive electrode material according to claim 6, characterized in that: The primary sintering temperature is 550-850°C and the time is 4-10 hours; And / or, the secondary sintering temperature is 500-800° C. and the time is 2-6 hours; and / or, in step (1), adjusting the solid content to 30% to 45% by using water; And / or, in the wet sand milling, the sand milling particle size D50 is controlled to be 0.2-0.5 μm; And / or, the inlet air temperature of the spray drying is 220-280°C, and the outlet air temperature is 90-120°C; And / or, the pulverization is air flow pulverization, and the final air powder particle size meets the following requirements: D10 ≥ 0.20 μm, D50 is 0.3-1.1 μm, D90 ≤ 10 μm, and 1.0 ≤ (D90-D10) / D50 ≤ 3.0; and / or, the gaseous carbon source comprises at least one of methane, ethane, ethylene, and acetylene; And / or, the flow rate of the gaseous carbon source is 0.1~0.6L / min.

10. The method for preparing lithium manganese iron phosphate positive electrode material according to claim 9, characterized in that: In the wet sand grinding, the sand grinding particle size D50 is controlled to be 0.35-0.40 μm; And / or, the pulverization is air flow pulverization, and the final air powder particle size satisfies: D50 is 0.4-0.6 um; And / or, the flow rate of the gaseous carbon source is 0.2~0.5L / min.

11. A lithium-ion battery, characterized in that: The raw materials include the lithium iron manganese phosphate positive electrode material according to any one of claims 1 to 5, or the lithium iron manganese phosphate positive electrode material prepared by the method according to any one of claims 6 to 10.

12. An electrical equipment, characterized in that: Including the lithium ion battery according to claim 11.

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