CN-122010077-A - Preparation method of carbon-coated multi-ion gradient co-doped lithium iron phosphate positive electrode material

CN122010077ACN 122010077 ACN122010077 ACN 122010077ACN-122010077-A

Abstract

The invention discloses a preparation method of a carbon-coated multi-ion gradient co-doped lithium iron phosphate positive electrode material, which comprises the following steps of dissolving soluble ferrous salt in water, adjusting pH and oxidizing to obtain an iron source solution A, dissolving soluble phosphate in water, adjusting pH to obtain a phosphorus source solution B, loading at least two doped ion solutions on a carbonizable porous organic carrier to obtain a porous organic carrier loaded with doped ions, synchronously adding the phosphorus source solution B and the porous organic carrier loaded with doped ions into the iron source solution A in a parallel flow incremental dropwise adding mode under stirring and constant temperature conditions, performing aging reaction after dropwise adding to obtain gradient doped ferric phosphate slurry, filtering, drying, calcining, cooling, crushing and screening the slurry to obtain a gradient doped ferric phosphate precursor, mixing the precursor with a lithium source and a carbon source, and calcining at high temperature under an inert atmosphere to obtain the carbon-coated multi-ion gradient co-doped lithium iron phosphate positive electrode material.

Inventors

DONG RUI
XIE WEI
XIE KE
SU RUI
PENG SHUAIHUA
Zhong Qingpeng
CAI QUAN
LI WEI
YU HONGTING

Assignees

广东华电储能有限公司
中国华电集团有限公司广东分公司

Dates

Publication Date: 20260512
Application Date: 20260122

Claims (10)

1. The preparation method of the carbon-coated multi-ion gradient co-doped lithium iron phosphate positive electrode material is characterized by comprising the following steps of: Dissolving soluble ferrous salt in water, regulating pH and oxidizing to obtain an iron source solution A; Dissolving soluble phosphate in water, and regulating pH to obtain phosphorus source solution B; Loading at least two doping ion solutions on a carbonizable porous organic carrier to obtain a porous organic carrier loaded with doping ions; under the conditions of stirring and constant temperature, synchronously adding the phosphorus source solution B and the porous organic carrier loaded with doped ions into the iron source solution A in a parallel flow increasing dropwise adding mode, and performing aging reaction after dropwise adding to obtain gradient doped ferric phosphate dihydrate slurry; Filtering, drying, calcining, cooling, crushing and screening the slurry to obtain a gradient doped ferric phosphate precursor; And mixing the precursor with a lithium source and a carbon source, and calcining at a high temperature in an inert atmosphere to obtain the carbon-coated multi-ion gradient co-doped lithium iron phosphate anode material.
2. The process according to claim 1, wherein the carbonizable porous organic carrier has a specific surface area of 20 to 200m 2 /g.
3. The method of claim 1, wherein the carbonizable porous organic carrier is a lignocellulosic particle, a phenolic microsphere, a polypyrrole sphere, a polyaniline sphere, or a combination thereof.
4. The method according to claim 1, wherein the doping ions are at least two selected from the group consisting of boron ions, magnesium ions, aluminum ions, manganese ions, titanium ions, zinc ions, sodium ions, potassium ions, calcium ions, sulfur ions, phosphorus ions, fluorine ions, and chlorine ions.
5. The method according to claim 1, wherein the porous organic carrier is added at a rate of 0.1 to 5 g/min in the parallel flow incremental dropwise addition manner, and gradually increases during the dropwise addition.
6. The method according to claim 1, wherein the calcination step is performed at 600 to 900 ℃ in a nitrogen, argon or a mixed gas thereof.
7. The method according to claim 1, wherein the lithium source is one or more selected from lithium carbonate, lithium hydroxide, lithium chloride, lithium nitrate, and lithium acetate, and the carbon source is one or more selected from glucose, sucrose, polyvinyl alcohol, caramel, citric acid, asphalt, ethanol, and cellulose acetate.
8. The method according to claim 1, wherein the iron source is one or more selected from ferrous sulfate heptahydrate, ferrous sulfate anhydrous, ferrous chloride, ferrous nitrate, and ferrous oxalate, and the phosphorus source is one or more selected from ammonium dihydrogen phosphate, monoammonium phosphate, phosphoric acid, sodium dihydrogen phosphate, and potassium dihydrogen phosphate.
9. The method of claim 1, wherein the mass ratio of the porous organic carrier loaded with the dopant ions to the dopant ion solution is 1:5 to 1:20.
10. The method of claim 1, wherein the carbon source comprises 1-10% of the precursor mass.

Description

Preparation method of carbon-coated multi-ion gradient co-doped lithium iron phosphate positive electrode material Technical Field The application relates to the field of battery materials, in particular to a preparation method of a carbon-coated multi-ion gradient co-doped lithium iron phosphate positive electrode material. Background Lithium iron phosphate (LiFePO 4) is used as a positive electrode material of a lithium ion battery, and is widely applied to power batteries and energy storage systems due to the advantages of high safety, long cycle life, environmental friendliness and the like. Particularly in a semi-solid battery system, the lithium iron phosphate positive electrode material shows good electrochemical performance and structural stability, and becomes a research hot spot. Currently, modification by elemental doping is one of the important means to enhance the electrochemical performance of lithium iron phosphate. In the prior art, the main challenge of doping modification of lithium iron phosphate is that the uniformity of distribution and gradient control of doping elements are difficult to realize. Traditional doping methods such as a solid phase method, a liquid phase coprecipitation method and the like often lead to uneven distribution of doping elements in the material, and an ideal gradient structure cannot be formed. Such uneven distribution can limit the exertion of doping effects, affect the electron conductivity and ion diffusion rate of the material, and further affect the rate capability and cycling stability of the battery. How to realize gradient distribution of doping elements in lithium iron phosphate is a core technical problem faced by the modification of the current lithium iron phosphate anode material. Disclosure of Invention The application provides a preparation method of a carbon-coated multi-ion gradient co-doped lithium iron phosphate anode material, which aims to solve the technical problem that gradient distribution control of doping elements in lithium iron phosphate is difficult. The application provides a preparation method of a carbon-coated multi-ion gradient co-doped lithium iron phosphate positive electrode material, which aims to solve the technical problems of multi-ion gradient distribution, uniform doping and improvement of structural stability and cycle life of the lithium iron phosphate positive electrode material. The application provides a preparation method of a carbon-coated multi-ion gradient co-doped lithium iron phosphate positive electrode material, which comprises the following steps: Dissolving soluble ferrous salt in water, regulating pH and oxidizing to obtain an iron source solution A; Dissolving soluble phosphate in water, and regulating pH to obtain phosphorus source solution B; Loading at least two doping ion solutions on a carbonizable porous organic carrier to obtain a porous organic carrier loaded with doping ions; Under the conditions of stirring and constant temperature, synchronously adding a phosphorus source solution B and a porous organic carrier loaded with doped ions into an iron source solution A in a parallel flow increasing dropwise adding mode, and carrying out aging reaction after dropwise adding to obtain gradient doped ferric phosphate dihydrate slurry; Filtering, drying, calcining, cooling, crushing and screening the slurry to obtain a gradient doped ferric phosphate precursor; and mixing the precursor with a lithium source and a carbon source, and calcining at a high temperature in an inert atmosphere to obtain the carbon-coated multi-ion gradient co-doped lithium iron phosphate anode material. According to the invention, by introducing the carbonizable porous organic carrier (such as lignin fiber particles), the efficient slow release and the spatial gradient regulation of various doping ions are realized. Specifically, the porous organic carrier has a high specific surface area and a rich pore structure, and can fully adsorb and store a large amount of metal or nonmetal ions in the doped ion solution. When the carriers loaded with the doping ions are added into the iron source solution A at an increasing speed, the doping ions in the carriers are not released instantaneously, but gradually diffuse into a reaction system along with the progress of the reaction. Due to the physical adsorption and chemical combination of the pore canal structure of the carrier and the organic framework to the ions, the release rate of the doped ions is effectively regulated. In the parallel flow incremental dropwise adding reaction process, the quantity of carriers added initially is small, the concentration of released doping ions is low, and the doping degree of a precursor core area generated by reacting with an iron source and a phosphorus source is low. As the reaction proceeds, the carrier addition rate is increased gradually, and the concentration of subsequently released dopant ions is increased, so that the doping degree o