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CN-121983537-A - Lithium iron manganese phosphate composite material, preparation method thereof, positive plate and battery

CN121983537ACN 121983537 ACN121983537 ACN 121983537ACN-121983537-A

Abstract

The application provides a lithium iron manganese phosphate composite material, a preparation method thereof, a positive plate and a battery. The lithium iron manganese phosphate composite material comprises lithium iron manganese phosphate particles and a carbon layer coated on at least part of the surfaces of the lithium iron manganese phosphate particles, wherein the lithium iron manganese phosphate particles comprise first lithium iron manganese phosphate particles and second lithium iron manganese phosphate particles, the primary particle size of the first lithium iron manganese phosphate particles is more than or equal to 800nm and less than or equal to D V 50≤1500nm,D V and less than or equal to 2500nm, and the primary particle size of the second lithium iron manganese phosphate particles is more than or equal to 50nm and less than or equal to D V 50≤150nm,D V and less than or equal to 300nm. According to the application, the first lithium iron manganese phosphate particles and the second lithium iron manganese phosphate particles are compounded, so that the particle stacking structure of the lithium iron manganese phosphate composite material is optimized, the compaction density of the material is improved from the physical aspect, and the high compaction density and the electrochemical performance of the positive electrode material are realized.

Inventors

  • FENG MINGYAN
  • ZHAO SUYING
  • PAN KUN
  • WANG SIJIA
  • YUAN YONG
  • KONG DEXIANG

Assignees

  • 天津容百斯科兰德科技有限公司

Dates

Publication Date
20260505
Application Date
20260113

Claims (10)

  1. 1. The lithium iron manganese phosphate composite material is characterized by comprising lithium iron manganese phosphate particles and a carbon layer coated on at least part of the surfaces of the lithium iron manganese phosphate particles, wherein the lithium iron manganese phosphate particles comprise first lithium iron manganese phosphate particles and second lithium iron manganese phosphate particles; the primary particle size of the first lithium iron manganese phosphate particles is more than or equal to 800nm and less than or equal to D V 50≤1500nm,D V < 99 > and less than or equal to 2500nm; The primary particle size of the second lithium iron manganese phosphate particles is 50 nm-300 nm or less and D V 50≤150nm,D V -99 nm or less.
  2. 2. The lithium iron manganese phosphate composite material according to claim 1, wherein the first lithium iron manganese phosphate particles and the second lithium iron manganese phosphate particles are prepared by mixing a first lithium iron manganese phosphate precursor and a second lithium iron manganese phosphate precursor; The manganese source in the first lithium iron manganese phosphate precursor comprises at least one of manganese carbonate, manganese oxalate and manganese ammonia phosphate; The manganese source in the second lithium iron manganese phosphate precursor comprises at least one of manganous oxide, manganese dioxide, manganese phosphate and manganous oxide.
  3. 3. The lithium iron manganese phosphate composite material according to claim 1, wherein in the first lithium iron manganese phosphate particles, the molar ratio of Li/P is 1.02 to 1.05, and the molar ratio of mn/Fe is 0.15 to 0.65; And/or; in the second lithium iron manganese phosphate particles, the molar ratio of Li/P is 1.05-1.10, and the molar ratio of Mn/Fe is 1.2-4.0.
  4. 4. The lithium manganese iron phosphate composite material according to claim 1, wherein the first lithium manganese iron phosphate particles further comprise M1 element therein; M1 comprises at least Ti; and/or M1 element further comprises one or more of Mg, ni, co, nb, cr, la, sb, te, sr, W, in, Y elements; And/or the mass ratio of M1 in the first lithium iron manganese phosphate particles is 0.3-0.8%; and/or the mass ratio of Ti element in the first lithium iron manganese phosphate particles is 0.3% -0.5%; and/or the molar ratio of (Mn+Fe+M1)/P in the first lithium iron manganese phosphate particles is 0.96-0.975.
  5. 5. The lithium manganese iron phosphate composite material according to claim 1 or 4, wherein the second lithium manganese iron phosphate particles further comprise M2 element therein; The M2 element includes one or more of Mg, ni, co, nb, cr, la, sb, te, sr, W, in, Y elements; And/or in the second lithium iron manganese phosphate particles, the mass ratio of M2 is 0.1-0.3%; and/or the molar ratio of (Mn+Fe+M2)/P in the second lithium iron manganese phosphate particles is 0.975-1.00.
  6. 6. The lithium manganese iron phosphate composite material according to claim 1, wherein the primary particles of the first lithium manganese iron phosphate particles have a specific surface area of 13-16m 2 /g, and the secondary particles of the second lithium manganese iron phosphate particles have a specific surface area of 17-25 m 2 /g; And/or; the mass ratio of the first lithium iron manganese phosphate particles to the second lithium iron manganese phosphate particles is (0.1-1) 1.
  7. 7. A method of preparing a lithium iron manganese phosphate composite material according to any one of claims 1 to 6, comprising: s1, mixing and grinding a manganese source, an iron source, a phosphorus source, lithium salt and a carbon source, spray-drying and sintering to obtain a first lithium iron manganese phosphate precursor, wherein the manganese source comprises at least one of manganese carbonate, manganese oxalate and manganese ammonia phosphate; s2, mixing and grinding a manganese source, an iron source, a phosphorus source, lithium salt and a carbon source, spray-drying and sintering to obtain a second lithium iron manganese phosphate precursor, wherein the manganese source comprises at least one of manganous oxide, manganese dioxide, manganese phosphate and manganese sesquioxide; And S3, dispersing the first lithium iron manganese phosphate precursor and the second lithium iron manganese phosphate precursor in an organic solvent, grinding, press-filtering and drying to obtain a mixed material, and sintering the mixed material to obtain the lithium iron manganese phosphate composite material.
  8. 8. The method according to claim 7, wherein in the step S1, an M1 source is further added before the mixing and grinding, wherein the M1 source comprises a compound containing M1 element, and the M1 element comprises at least Ti; and/or M1 element further comprises one or more of Mg, ni, co, nb, cr, la, sb, te, sr, W, in, Y elements; And/or; in the step S2, an M2 source is also added before mixing and grinding, wherein the M2 source comprises a compound containing M2 element, and the M2 element comprises one or more of Mg, ni, co, nb, cr, la, sb, te, sr, W, in, Y elements; And/or; in the step S1, the sintering temperature is 780-820 ℃ and the sintering time is 8-10h; And/or; In the step S2, the sintering temperature is 700-780 ℃ and the sintering time is 6-10h; And/or; In step S3, the organic solvent includes at least one of ethanol, ethylene glycol, methanol, glycerol, and acetone; And/or; In the step S3, the sintering temperature is 680-750 ℃ and the sintering time is 3-6h; And/or; In step S3, the particles are ground to a D V 500 of 0.5-1.0 μm.
  9. 9. A positive electrode sheet, characterized in that the positive electrode sheet comprises the lithium iron manganese phosphate composite material according to any one of claims 1 to 6.
  10. 10. A battery comprising the positive electrode sheet according to claim 9.

Description

Lithium iron manganese phosphate composite material, preparation method thereof, positive plate and battery Technical Field The application relates to the technical field of batteries, in particular to a lithium iron manganese phosphate composite material, a preparation method thereof, a positive plate and a battery. Background With the high requirement of new energy industry on safety performance, the lithium iron phosphate material and the battery thereof are widely applied and expanded. At present, the lithium iron phosphate material has limit value in terms of compaction density and specific capacity, and the energy density reaches the maximum value. While technology is continually breaking through, higher and safer energy density materials are needed for optimization. The lithium iron manganese phosphate material is a homologous derivative of the lithium iron phosphate material, and a part of manganese element is doped at the position of iron element in the lithium iron phosphate system, so that the manganese element brings a higher voltage platform, and a higher energy density is possible to achieve. At present, the manganese iron phosphate lithium material improves a voltage platform due to the existence of manganese element, and compared with the iron phosphate lithium, the voltage platform can be improved by about 12.5 percent. However, lithium iron manganese phosphate materials have a somewhat lower compacted density. The powder compaction density of the lithium iron phosphate material can reach 2.65g/cm 3, while the powder compaction density of the lithium iron manganese phosphate material is only 2.30g/cm 3, and the compaction density is reduced by about 13.0 percent, so that the energy density of the lithium iron manganese phosphate material is not superior. In the prior art, the difficulty of the cooperative improvement of high compaction density and electrochemical performance is high, the ion diffusion path is prolonged and the multiplying power performance is influenced due to the fact that the mere pursuit of particle densification is likely to cause the fact that the stacking density is reduced due to the fact that the particle is excessively refined, and the energy density requirement is difficult to meet. Therefore, developing a lithium iron manganese phosphate material with both high compaction density and electrochemical performance is a technical problem to be solved. Disclosure of Invention The lithium iron manganese phosphate composite material, the preparation method thereof, the positive plate and the battery can obtain the lithium iron manganese phosphate material with high compaction density and good electrochemical performance. In a first aspect, the present application provides a lithium iron manganese phosphate composite material comprising lithium iron manganese phosphate particles and a carbon layer coated on at least a portion of the surface of the lithium iron manganese phosphate particles, the lithium iron manganese phosphate particles comprising first lithium iron manganese phosphate particles and second lithium iron manganese phosphate particles; the primary particle size of the first lithium iron manganese phosphate particles is more than or equal to 800nm and less than or equal to D V50≤1500nm,DV < 99 > and less than or equal to 2500nm; The primary particle size of the second lithium iron manganese phosphate particles is 50 nm-300 nm or less and D V50≤150nm,DV -99 nm or less. In one possible embodiment, the first lithium iron manganese phosphate particles and the second lithium iron manganese phosphate particles are prepared by mixing a first lithium iron manganese phosphate precursor and a second lithium iron manganese phosphate precursor; The manganese source in the first lithium iron manganese phosphate precursor comprises at least one of manganese carbonate, manganese oxalate and manganese ammonia phosphate; The manganese source in the second lithium iron manganese phosphate precursor comprises at least one of manganous oxide, manganese dioxide, manganese phosphate and manganous oxide. In one possible embodiment, in the first lithium iron manganese phosphate particles, the molar ratio of Li/P is 1.02 to 1.05, and the molar ratio of mn/Fe is 0.15 to 0.65; And/or; in the second lithium iron manganese phosphate particles, the molar ratio of Li/P is 1.05-1.10, and the molar ratio of Mn/Fe is 1.2-4.0. In one possible embodiment, the first lithium iron manganese phosphate particles further include an M1 element therein; M1 comprises at least Ti; and/or M1 element further comprises one or more of Mg, ni, co, nb, cr, la, sb, te, sr, W, in, Y elements; And/or the mass ratio of M1 in the first lithium iron manganese phosphate particles is 0.3-0.8%; and/or the mass ratio of Ti element in the first lithium iron manganese phosphate particles is 0.3% -0.5%; and/or the molar ratio of (Mn+Fe+M1)/P in the first lithium iron manganese phosphate particles is 0.96-0.975. In one pos