CN-121974319-A - Preparation method of lithium iron manganese phosphate positive electrode material and lithium iron manganese phosphate battery

Abstract

The embodiment of the invention provides a preparation method of a lithium iron manganese phosphate positive electrode material and a lithium iron manganese phosphate battery, wherein the method comprises the steps of dissolving MnSO 4 、FeSO 4 、NbCl 5 according to a preset stoichiometric ratio to obtain an initial mixed solution, adjusting the pH of the initial mixed solution to a pH gradient of 8.5-7.0, carrying out filtering treatment to obtain a precursor, and placing the initial lithium iron manganese phosphate positive electrode material into the precursor to be calcined in a nitrogen atmosphere at 650 ℃ to obtain a gradient niobium-doped lithium iron manganese phosphate positive electrode material, wherein the niobium gradient of the gradient niobium-doped lithium iron manganese phosphate positive electrode material is from an inner core Nb 2 at to a shell of 0.5 at%. According to the embodiment of the invention, the gradient niobium doping treatment of the lithium iron manganese phosphate anode material is adopted, so that the electronic conductivity is improved and the dissolution of manganese is inhibited.

Inventors

• LI XINQI
• DENG ZHIYONG
• WEN QIAN
• XIANG LIU

Assignees

• 赛力斯汽车有限公司

Dates

Publication Date

20260505

Application Date

20260105

Claims (10)

1. 1. The preparation method of the lithium iron manganese phosphate anode material is characterized by comprising the following steps of: dissolving MnSO 4 、FeSO 4 、NbCl 5 according to a preset stoichiometric ratio to obtain an initial mixed solution; adjusting the pH of the initial mixed solution to a pH gradient of 8.5-7.0, and filtering to obtain a precursor; And (3) placing the initial lithium manganese iron phosphate anode material into the precursor to be calcined in a nitrogen atmosphere at 650 ℃ to obtain the gradient niobium-doped lithium manganese iron phosphate anode material, wherein the niobium gradient of the gradient niobium-doped lithium manganese iron phosphate anode material is from an inner core Nb 2 at to an outer shell of 0.5 at percent.
2. 2. The method as recited in claim 1, further comprising: Coating LiFePO 4 on the surface of the gradient niobium doped lithium iron manganese phosphate anode material to form an LFP buffer layer; And introducing TiCl 4 and NH into the gradient niobium-doped lithium iron manganese phosphate anode material at 450 ℃ to generate a TiN conductive layer on the outer layer of the gradient niobium-doped lithium iron manganese phosphate anode material.
3. 3. The lithium iron manganese phosphate positive electrode material is characterized in that the lithium iron manganese phosphate positive electrode material is prepared and generated according to the preparation method of the lithium iron manganese phosphate positive electrode material in claim 1.
4. 4. The lithium iron manganese phosphate positive electrode material according to claim 3, wherein the lithium iron manganese phosphate positive electrode material is coated with an LFP buffer layer and a TiN conductive layer.
5. 5. The lithium iron manganese phosphate positive electrode material according to claim 4, wherein the LFP buffer layer has a thickness of 20nm and the TiN conductive layer has a thickness of 3nm.
6. 6. The lithium iron manganese phosphate positive electrode material according to claim 4, wherein the LFP buffer layer is LiFePO 4 coated on the surface of the gradient niobium doped lithium iron manganese phosphate positive electrode material.
7. 7. The lithium manganese iron phosphate positive electrode material according to claim 4, wherein the TiN conductive layer is formed by introducing TiCl and NH into the gradient niobium doped lithium manganese iron phosphate positive electrode material at 450 ℃ and forming an outer layer of the gradient niobium doped lithium manganese iron phosphate positive electrode material.
8. 8. A lithium iron manganese phosphate battery, characterized in that the lithium iron manganese phosphate battery comprises the lithium iron manganese phosphate positive electrode material prepared by the preparation method of the lithium iron manganese phosphate positive electrode material according to claim 1.
9. 9. The lithium iron manganese phosphate battery of claim 8, further comprising a pre-lithiated silicon carbon negative electrode material of pre-lithiated SiO x @ C (x = 0.8-1.2).
10. 10. The lithium iron manganese phosphate battery of claim 8 further comprising a highly fluorinated electrolyte comprising LiDFOB and TTSPI.

Description

Preparation method of lithium iron manganese phosphate positive electrode material and lithium iron manganese phosphate battery Technical Field The invention relates to the technical field of batteries, in particular to a preparation method of a lithium iron manganese phosphate positive electrode material and a lithium iron manganese phosphate battery. Background At present, a lithium iron manganese phosphate battery is used as an upgrade version of lithium iron phosphate (LFP), and by means of a higher voltage platform (3.8-4.1V) and energy density improvement of 15-20% (reaching 180-200 Wh/kg), the lithium iron manganese phosphate battery becomes a research hot spot of the current lithium electricity technology, and has the core advantages of high safety (inheriting an olivine structure of the LFP, excellent heat stability), low cost (rich manganese resources, material cost approaching the LFP and far lower than that of a ternary battery), environmental friendliness (no rare metals such as cobalt and nickel, and the like, and meets the requirement of sustainable development). However, lithium iron manganese phosphate LMFP still faces technical bottlenecks such as cyclic decay and poor intrinsic conductivity due to manganese dissolution. Disclosure of Invention In view of the above problems, a method for preparing a lithium iron manganese phosphate positive electrode material and a lithium iron manganese phosphate battery have been proposed to overcome or at least partially solve the above problems, including: The preparation method of the lithium iron manganese phosphate anode material is characterized by comprising the following steps of: dissolving MnSO 4、FeSO4、NbCl5 according to a preset stoichiometric ratio to obtain an initial mixed solution; adjusting the pH of the initial mixed solution to a pH gradient of 8.5-7.0, and filtering to obtain a precursor; And (3) placing the initial lithium manganese iron phosphate anode material into the precursor to be calcined in a nitrogen atmosphere at 650 ℃ to obtain the gradient niobium-doped lithium manganese iron phosphate anode material, wherein the niobium gradient of the gradient niobium-doped lithium manganese iron phosphate anode material is from an inner core Nb 2 at to an outer shell of 0.5 at percent. Optionally, the method further comprises: Coating LiFePO 4 on the surface of the gradient niobium doped lithium iron manganese phosphate anode material to form an LFP buffer layer; And introducing TiCl 4 and NH into the gradient niobium-doped lithium iron manganese phosphate anode material at 450 ℃ to generate a TiN conductive layer on the outer layer of the gradient niobium-doped lithium iron manganese phosphate anode material. The lithium manganese iron phosphate positive electrode material is a niobium doped lithium manganese iron phosphate positive electrode material with a gradient of from an inner core Nb 2 at to an outer shell of 0.5 at percent. Optionally, the lithium iron manganese phosphate anode material is coated by an LFP buffer layer and a TiN conductive layer. Optionally, the LFP buffer layer has a thickness of 20nm and the TiN conductive layer has a thickness of 3nm. Optionally, the LFP buffer layer is LiFePO 4 coated on the surface of the gradient niobium doped lithium iron manganese phosphate anode material. Optionally, the TiN conductive layer is formed by introducing TiCl and NH into the gradient niobium-doped lithium iron manganese phosphate anode material at 450 ℃ and forming an outer layer of the gradient niobium-doped lithium iron manganese phosphate anode material. A lithium iron manganese phosphate battery comprising a lithium iron manganese phosphate positive electrode material prepared according to claim 1. Optionally, the lithium iron manganese phosphate battery further comprises a pre-lithiated silicon-carbon anode material, wherein the pre-lithiated silicon-carbon anode material is pre-lithiated Si x @C (x=0.8-1.2). Optionally, the lithium iron manganese phosphate battery further comprises a highly fluorinated electrolyte containing LiDFOB and TTSPI. The embodiment of the invention has the following advantages: In the embodiment of the invention, the gradient niobium doping treatment is carried out on the lithium manganese iron phosphate anode material, so that the electronic conductivity is improved and the manganese dissolution is inhibited. In addition, in the embodiment of the invention, the core-shell cladding synergy can realize the optimization of the interface stability, wherein the core-shell comprises an inner layer and an outer layer, the LFP buffer layer adopted by the inner layer can relieve 10% of volume expansion caused by LiMnPO 4→MnPO4 phase transition, the TiN conductive layer adopted by the outer layer can provide high electron conductivity (10 4 S/cm), the interface impedance is reduced to 8 omega cm < 2 > (35 omega cm < 2 > of traditional carbon cladding), and meanwhile, the core-shell is high-voltage (>