CN-121974322-A - Lithium iron phosphate battery positive electrode material, and preparation method and application thereof

CN121974322ACN 121974322 ACN121974322 ACN 121974322ACN-121974322-A

Abstract

The invention discloses a lithium iron phosphate battery anode material and a preparation method and application thereof, wherein the preparation method comprises the steps of S1, mixing a chelating agent, lithium salt, ferric salt and phosphorus salt to obtain a first reaction system, carrying out chelating reaction under an ultrasonic auxiliary condition to obtain a precursor chelated with metal ions, wherein the chelating agent comprises dihydroxyethyl glycine, the molar concentration of lithium salt, the molar concentration of ferric salt and the molar concentration of phosphorus salt in the first reaction system are all 0.1-0.5mol/L, S2, mixing the precursor obtained in the step S1 with a carbon source compound to obtain a second reaction system, and carrying out carbonization reaction on the obtained second reaction system to obtain the lithium iron phosphate battery anode material. According to the invention, dihydroxyethyl glycine with chelation effect on ferric ions is added, so that the defect of iron-lithium inversion is reduced, the crystallinity of lithium iron phosphate crystals is increased, the gram capacity of charge and discharge of a lithium ion battery is improved, and the discharge efficiency of the lithium iron phosphate battery is improved.

Inventors

ZENG QINGYUAN
LI RENKUN
XIANG BINGQIU
JIANG SEN
YAN YANLEI

Assignees

广东瑞浦兰钧能源有限公司

Dates

Publication Date: 20260505
Application Date: 20260130

Claims (9)

1. The preparation method of the lithium iron phosphate battery anode material is characterized by comprising the following steps: S1, mixing a chelating agent, lithium salt, ferric salt and phosphorus salt to obtain a first reaction system, and carrying out chelating reaction under the ultrasonic auxiliary condition to obtain a precursor for chelating metal ions, wherein the chelating agent comprises dihydroxyethyl glycine, and the molar concentration of dihydroxyethyl glycine, lithium salt, ferric salt and phosphorus salt in the first reaction system is 0.1-0.5mol/L; S2, mixing the precursor obtained in the step S1 with a carbon source compound to obtain a second reaction system, and performing carbonization reaction on the obtained second reaction system to obtain the lithium iron phosphate battery anode material.
2. The method for preparing a positive electrode material of a lithium iron phosphate battery according to claim 1, wherein in the step S1, the time of the chelation reaction is 1-2h.
3. The method for preparing the lithium iron phosphate battery positive electrode material according to claim 1, wherein in the step S1, the obtained precursor is subjected to aftertreatment, and the aftertreatment specifically comprises the steps of cleaning the obtained precursor by deionized water, and soaking and dehydrating the cleaned precursor by absolute ethyl alcohol.
4. The preparation method of the lithium iron phosphate battery positive electrode material is characterized in that the precursor and the carbon source compound are mixed through ball milling, and the mass percentage of the carbon source compound in the second reaction system is 10-15wt%.
5. The method for preparing a positive electrode material of a lithium iron phosphate battery according to claim 1, wherein the carbonization reaction is carried out in a tube furnace, and the temperature rise process of the carbonization reaction is to rise to 750-790 ℃ at a temperature rise rate of 5-8 ℃ per minute, and then the temperature is kept for 7-11h.
6. The method for preparing a positive electrode material of a lithium iron phosphate battery according to claim 1, wherein the lithium salt comprises one or more of lithium nitrate, lithium carbonate, lithium hydroxide, lithium sulfate, lithium acetate, lithium trifluoromethane sulfonate and lithium oxalate, and/or, The ferric salt comprises one or more of ferric chloride, ferric sulfate, ferric nitrate, ferric phosphate and ferric citrate, and/or, The phosphorus salt comprises one or more of monoammonium phosphate, diammonium phosphate, phosphoric acid and lithium dihydrogen phosphate, and/or, The carbon source compound comprises one or more of glucose, sucrose, citric acid, polyethylene glycol, polyvinyl butyral, polyvinyl alcohol, polyacrylonitrile, starch and cellulose.
7. A lithium iron phosphate battery positive electrode material is characterized in that the lithium iron phosphate battery positive electrode material is prepared by the preparation method of the lithium iron phosphate battery positive electrode material according to any one of claims 1-6.
8. A lithium ion battery, which is characterized in that the lithium iron phosphate battery positive electrode material is prepared by the method of claim 7.
9. An electric drive device characterized in that it comprises the lithium ion battery as claimed in claim 8.

Description

Lithium iron phosphate battery positive electrode material, and preparation method and application thereof Technical Field The invention relates to the technical field of lithium ion batteries, in particular to a lithium iron phosphate battery anode material and a preparation method and application thereof. Background The lithium iron phosphate (LiFePO 4) has better safety performance because the lithium iron phosphate has a good olivine structure and consists of LiO6 octahedron, feO6 octahedron and PO4 tetrahedron units, P-O bonds in the lithium iron phosphate crystal are stable and difficult to decompose, but oxygen atoms in the PO4 tetrahedron separate the FeO6 octahedron inside the LiFePO4 crystal structure so that the FeO6 octahedron cannot form a continuous octahedral structure, thereby destroying an integral conductive network structure inside and preventing Li + from diffusing, and leading to lower electronic conductivity of the LiFePO4 (only 10-10 to 10-9S cm -1). Therefore, liFePO4 was determined to be suitable for charging and discharging only at low current densities. Disclosure of Invention The invention aims to solve the problems and provide a lithium iron phosphate battery anode material, a preparation method and application thereof. In order to solve the technical problems, the technical scheme adopted by the invention is as follows: in a first aspect, the present invention provides a method for preparing a positive electrode material of a lithium iron phosphate battery, comprising the steps of: S1, mixing a chelating agent, lithium salt, ferric salt and phosphorus salt to obtain a first reaction system, and carrying out chelating reaction under the ultrasonic auxiliary condition to obtain a precursor for chelating metal ions, wherein the chelating agent comprises dihydroxyethyl glycine, and the molar concentration of dihydroxyethyl glycine, lithium salt, ferric salt and phosphorus salt in the first reaction system is 0.1-0.5mol/L; S2, mixing the precursor obtained in the step S1 with a carbon source compound to obtain a second reaction system, and performing carbonization reaction on the obtained second reaction system to obtain the lithium iron phosphate battery anode material. Optionally, in step S1, the time of the chelation reaction is 1-2h. Optionally, in step S1, the method further comprises post-treatment of the obtained precursor, wherein the post-treatment specifically comprises the steps of cleaning the obtained precursor by deionized water, and soaking and dehydrating the cleaned precursor by absolute ethyl alcohol. Optionally, the precursor and the carbon source compound are mixed by ball milling, wherein the carbon source compound accounts for 10-15wt% in the second reaction system. Optionally, the carbonization reaction is carried out in a tube furnace, and the heating process of the carbonization reaction is to heat up to 750-790 ℃ at a heating rate of 5-8 ℃ per minute, and then heat preservation is carried out for 7-11h. Optionally, the lithium salt comprises one or more of lithium nitrate, lithium carbonate, lithium hydroxide, lithium sulfate, lithium acetate, lithium trifluoromethane sulfonate and lithium oxalate, and/or, The ferric salt comprises one or more of ferric chloride, ferric sulfate, ferric nitrate, ferric phosphate and ferric citrate, and/or, The phosphorus salt comprises one or more of monoammonium phosphate, diammonium phosphate, phosphoric acid and lithium dihydrogen phosphate, and/or, The carbon source compound comprises one or more of glucose, sucrose, citric acid, polyethylene glycol, polyvinyl butyral, polyvinyl alcohol, polyacrylonitrile, starch and cellulose. In a second aspect, the present invention provides a lithium iron phosphate battery cathode material prepared by the preparation method of the lithium iron phosphate battery cathode material. In a third aspect, the present invention provides a lithium ion battery comprising a lithium iron phosphate battery cathode material as described above. In a fourth aspect, the present invention provides an electric drive comprising a lithium ion battery as described above. The invention has the beneficial effects that at least comprises: According to the preparation method of the lithium iron phosphate battery anode material, a first reaction system is obtained after a chelating agent is mixed with lithium salt, ferric salt and phosphorus salt, and a precursor chelated with metal ions is obtained under the condition of ultrasonic assistance; the preparation method comprises the steps of adding dihydroxyethyl glycine (Bicine) with chelation effect on ferric ions into a first reaction system, wherein the binding force between Bicine and Fe & lt3+ & gt is larger than that between Li & lt+ & gt in the early synthesis stage of the ferric lithium phosphate crystal, and the binding force is strong on the ferric ions and only has electrostatic attraction to the lithium ions, so that iron atoms are prevented from bei