CN-121990546-A - Five-generation high-compaction lithium iron phosphate material and preparation method thereof

CN121990546ACN 121990546 ACN121990546 ACN 121990546ACN-121990546-A

Abstract

The invention discloses a five-generation high-compaction lithium iron phosphate material and a preparation method thereof, comprising the following steps of respectively carrying out wet mixing, grinding and spray drying on two parts of iron sources, phosphorus sources, lithium sources, doping agents and carbon sources with different contents to obtain two parts of spray-dried materials, sintering and crushing to obtain a lithium iron phosphate semi-finished product A, B; mixing a part of the lithium iron phosphate semi-finished product B with a carbon source, a lithium source and a doping agent by a wet method, grinding, spray drying to obtain a spray drying material, sintering and crushing to obtain a lithium iron phosphate semi-finished product C, mixing the rest of the lithium iron phosphate semi-finished product B, the lithium iron phosphate semi-finished product A, C and the carbon source by a dry method according to a proportion, coating a layer of coating agent on the surface of the mixture, sintering and crushing to obtain the five-generation high-compaction lithium iron phosphate material. The invention adopts the semi-finished product of lithium iron phosphate to replace the traditional raw material, reduces the process cost, combines multiple sintering and special coating modes, and obtains the five-generation high-compaction lithium iron phosphate material with excellent electrochemical performance.

Inventors

JIANG NAN
SUN JIE
WEI YIHUA
MEI JING
HE JIANHAO
DONG YAOGANG

Assignees

湖北融通高科先进材料集团股份有限公司

Dates

Publication Date: 20260508
Application Date: 20260205

Claims (10)

1. The preparation method of the five-generation high-compaction lithium iron phosphate material is characterized by comprising the following steps of: Respectively carrying out wet mixing, grinding and spray drying on one part of a first iron source, a phosphorus source, a lithium source, a doping agent and a carbon source and the other part of a second iron source, a phosphorus source, a lithium source, a doping agent and a carbon source to obtain a first spray drying material and a second spray drying material; Mixing a part of the lithium iron phosphate semi-finished product B with a third carbon source, a lithium source and a doping agent by a wet method, grinding, and performing spray drying after reaching a second particle size to obtain a third spray drying material; And then the rest part of the lithium iron phosphate semi-finished product B, the lithium iron phosphate semi-finished product A, C and a fourth carbon source are mixed according to a proportion in a dry way to obtain a mixture, a layer of coating agent is coated on the surface of the mixture, and the mixture is sintered for the fourth time in an inert gas atmosphere and crushed to obtain the five-generation high-compaction lithium iron phosphate material.
2. The preparation method according to claim 1, wherein in the lithium iron phosphate semi-finished product a, the ratio of iron element to phosphorus element, fe/P, is 0.96-0.99, the ratio of lithium element to iron element, li/Fe, is 1.02-1.05, the carbon content is 0.3-0.7%, and the molar ratio of the first dopant to iron element is 0.001-0.01; In the lithium iron phosphate semi-finished product B, the molar ratio of Fe/P of iron element to phosphorus element is 0.96-0.99, the molar ratio of Li/Fe of lithium element to iron element is 1.02-1.05, the carbon content is 0.3-0.7%, and the molar ratio of the second doping agent to iron element is 0.01-0.02; In the lithium iron phosphate semi-finished product C, the carbon content is 1.5-2.0%, the third dopant content is 0.5-1.5% mol of the content of the part of the lithium iron phosphate semi-finished product B, and the third lithium source content is 0.1-2% mol of the content of the part of the lithium iron phosphate semi-finished product B; The wet mixing specifically comprises the step of wet mixing by taking deionized water as a solvent, wherein the solid content is 30% -40%.
3. The method according to claim 1, wherein the grinding is performed by one or more of a high-efficiency ball mill and a sand mill in series, the first particle size specifically comprises a particle size D50 of 0.25-0.45um, and the second particle size specifically comprises a particle size D50 of 0.2-0.3um.
4. The method according to claim 1, wherein the spray drying comprises setting the inlet air temperature to 220-280 ℃ and the outlet air temperature to 90-110 ℃.
5. The preparation method of the lithium iron phosphate semi-finished product A is characterized in that the primary sintering and crushing specifically comprises the steps of sintering by a roller hearth furnace or a box furnace to obtain a primary sintering product, setting the primary sintering temperature to be 750-850 ℃, setting the primary sintering time to be 6-8 hours, setting the sintering furnace pressure to be 50-200Pa, and carrying out jet milling on the primary sintering product to obtain the lithium iron phosphate semi-finished product A, wherein the particle size D50 of the primary sintering product A is 1.8-2.2um, and D99 is less than or equal to 20um; sintering by a roller hearth furnace or a box furnace to obtain a second sintering product, setting the second sintering temperature to be 650-750 ℃, setting the second sintering time to be 6-8 hours, and setting the sintering furnace pressure to be 50-200Pa, wherein the second sintering product is subjected to jet milling to obtain the lithium iron phosphate semi-finished product B, and the particle size D50 of the lithium iron phosphate semi-finished product B is 0.8-1.2um, and D99 is less than or equal to 20um; Sintering by a roller hearth furnace or a box furnace to obtain a third sintering product, setting the third sintering temperature to be 650-750 ℃, setting the third sintering time to be 6-8h, and setting the sintering furnace pressure to be 50-200Pa, and performing jet milling on the third sintering product to obtain the lithium iron phosphate semi-finished product C, wherein the particle size D10 of the semi-finished product C is more than or equal to 0.25um, the D50 is 0.5-0.7um, and the D99 is less than or equal to 10um; The fourth sintering is carried out by carrying out sintering by a roller hearth furnace or a box furnace to obtain a fourth sintering product, setting the fourth sintering temperature to be 700-800 ℃, setting the fourth sintering time to be 4-6h, setting the sintering furnace pressure to be 50-200Pa, and carrying out jet milling on the fourth sintering product to obtain the five-generation high-compaction lithium iron phosphate material, wherein the grain diameter D10 is more than or equal to 0.35um, the D50 is more than or equal to 1.5um, and the D99 is less than or equal to 10um.
6. The preparation method of the coating agent according to claim 1, wherein the coating agent accounts for 0.1-0.5% of the weight of the mixture, the coating agent is prepared by a coating machine or a honeycomb mill, the coating agent is prepared by mixing metal oxide such as nano aluminum oxide, zirconium oxide, niobium oxide and lithium phosphate or lithium dihydrogen phosphate according to a mass ratio of 1:1 with a volatile liquid as a medium, wherein the solid content is 50-60%, and grinding the mixture to 50-100nm, wherein the obtained suspension is the coating agent.
7. The method according to claim 1, wherein the first and second iron sources comprise one or more of iron phosphate, iron oxide, ferrous phosphate, and iron hydroxy phosphate, the first and second phosphorus sources comprise one or more of iron phosphate, ferrous phosphate, iron hydroxy phosphate, monoammonium phosphate, phosphoric acid, and lithium phosphate, the first, second, and third lithium sources comprise one or more of lithium carbonate, lithium hydroxide, and lithium phosphate, the first, second, and third carbon sources comprise organic carbon sources, and specifically comprise one or more of glucose, sucrose, polyethylene glycol, and polyvinyl alcohol, and the first, second, and third dopants comprise one or more of titanium dioxide, ammonium metavanadate, niobium pentoxide, and manganese carbonate.
8. The preparation method according to claim 1, wherein in the dry mixing according to the proportion, the lithium iron phosphate semi-finished product A, the rest of the lithium iron phosphate semi-finished product B and the lithium iron phosphate semi-finished product C are mixed according to the proportion of 7:1:2-2:3:5, the rest of the lithium iron phosphate semi-finished product B accounts for 20-60% of the lithium iron phosphate semi-finished product B, and the carbon content of the high-pressure solid lithium iron phosphate material is 1.2-1.5%.
9. The preparation method according to claim 1, wherein the dry mixing is performed by one or more of a VC mixer and a high mixer, the mixing revolution is set to 800-1200r/min, and the mixing time is set to 30-90min.
10. A five-generation high-compaction lithium iron phosphate material, characterized in that the material is prepared based on the preparation method according to any one of claims 1-9.

Description

Five-generation high-compaction lithium iron phosphate material and preparation method thereof Technical Field The invention relates to the technical field of battery materials, in particular to a five-generation high-compaction lithium iron phosphate material and a preparation method thereof. Background The lithium iron phosphate positive electrode material is a core electrode material in the fields of new energy power batteries and energy storage by virtue of high safety, long-cycle property and raw material availability, the technical development of the lithium iron phosphate positive electrode material always takes the compaction density as a core grip, the industry bottleneck of the volume energy density of a battery core is broken through, four-generation technical iteration is finished at present, the compaction density of powder of a four-generation product is about 2.60g/cm < 3 >, and the lithium iron phosphate positive electrode material is a mainstream application style in the current market. With the development of high-end new energy automobiles and large energy storage systems, industry has higher requirements on lithium iron phosphate materials, and not only is a five-generation high-compaction product with powder compaction density of more than or equal to 2.70g/cm < 3 >, but also high quick charge performance, low impedance and mass production stability are required. In the prior art, although the compaction density is gradually improved through particle grading, simple doping and carbon coating optimization, a plurality of short plates still exist, wherein the heterogeneous phase is easy to generate due to insufficient regulation and control of sintering process parameters, the uniformity of the carbon coating layer is poor, the consistency of the carbon coating layer and the doping element are weak, meanwhile, the control precision of the particle sphericity and the particle size distribution is limited, and the performance requirement of the five-generation product is difficult to meet. The research and development of the current five-generation high-compaction type lithium iron phosphate material becomes an industry competitive focus, but the preparation process of the material does not form a mature large-scale mass production scheme, and the problems of high process complexity, high cost, difficult control of performance consistency and the like are urgently solved, so that the development of an efficient preparation method suitable for the five-generation product becomes an urgent need for promoting the technical upgrading of the lithium iron phosphate material. Disclosure of Invention The invention aims to provide a five-generation high-compaction lithium iron phosphate material and a preparation method thereof, wherein a semi-finished product of lithium iron phosphate is adopted to replace the traditional raw material, the process cost is reduced, and the five-generation high-compaction lithium iron phosphate material obtained by combining multiple sintering and special coating modes has excellent electrochemical performance and stable high powder compaction. In order to achieve the above purpose, the invention adopts the following technical scheme: In a first aspect, the invention provides a method for preparing a five-generation high-compaction lithium iron phosphate material, which comprises the following steps: Respectively carrying out wet mixing, grinding and spray drying on one part of a first iron source, a phosphorus source, a lithium source, a doping agent and a carbon source and the other part of a second iron source, a phosphorus source, a lithium source, a doping agent and a carbon source to obtain a first spray drying material and a second spray drying material; Mixing a part of the lithium iron phosphate semi-finished product B with a third carbon source, a lithium source and a doping agent by a wet method, grinding, and performing spray drying after reaching a second particle size to obtain a third spray drying material; And then the rest part of the lithium iron phosphate semi-finished product B, the lithium iron phosphate semi-finished product A, C and a fourth carbon source are mixed according to a proportion in a dry way to obtain a mixture, a layer of coating agent is coated on the surface of the mixture, and the mixture is sintered for the fourth time in an inert gas atmosphere and crushed to obtain the five-generation high-compaction lithium iron phosphate material. In some possible embodiments, in the lithium iron phosphate semi-finished product a, the molar ratio of iron element to phosphorus element Fe/P is 0.96-0.99, the molar ratio of lithium element to iron element Li/Fe is 1.02-1.05, the carbon content is 0.3-0.7%, and the molar ratio of the first dopant to iron element is 0.001-0.01; in the lithium iron phosphate semi-finished product B, the molar ratio Fe/P of the iron element and the phosphorus element is 0.96-0.99, the molar ratio Li/Fe of the lith