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Modified lithium iron phosphate positive electrode material and preparation method thereof, positive plate and lithium secondary battery

A technology for lithium iron phosphate and positive electrode materials, applied in secondary batteries, secondary battery repair/maintenance, battery electrodes, etc., can solve problems such as poor conductivity and slow diffusion of lithium ions, and achieve improved energy density and good rate performance Effect

Active Publication Date: 2019-02-26
NINGDE AMPEREX TECH
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  • Description
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Problems solved by technology

[0009] In view of the problems existing in the background technology, the object of the present invention is to provide a modified lithium iron phosphate positive electrode material and a preparation method thereof, a positive electrode sheet, and a lithium secondary battery, and the modified lithium iron phosphate positive electrode material can overcome conventional doping The problems of poor electrical conductivity and slow lithium ion diffusion rate of lithium iron phosphate cathode materials can improve the energy density of lithium secondary batteries, and at the same time make lithium secondary batteries have good rate performance, high temperature storage performance and high temperature cycle performance

Method used

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  • Modified lithium iron phosphate positive electrode material and preparation method thereof, positive plate and lithium secondary battery
  • Modified lithium iron phosphate positive electrode material and preparation method thereof, positive plate and lithium secondary battery
  • Modified lithium iron phosphate positive electrode material and preparation method thereof, positive plate and lithium secondary battery

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preparation example Construction

[0028] Next, the preparation method of the modified lithium iron phosphate positive electrode material according to the second aspect of the present invention is described, which is used to prepare the modified lithium iron phosphate positive electrode material described in the first aspect of the present invention, including the steps: (1) Li source, M The source and the N source are dissolved in the solvent according to the molar ratio of Li, M, and N as x:a:b, stirred to obtain a mixed solution, and then sprayed onto the doped lithium iron phosphate LiFe α M' β PO 4 The surface is then calcined under a protective gas atmosphere, wherein, 2≤x≤8, 0<a≤1, 0≤b<1, 2≤y≤6, M is selected from Fe, Co, Mn, Ni, Zr, One of V, Nb, Mo, N selected from one of Al, Mg, Ti, Cr, Y, Sr, Si, W, Ga, Zn, 0.2≤α<1, 0<β≤0.8, M 'One selected from Ti, Mg, V, Mn, Cr, Zr, Nb, W; (2) mixing the material calcined in step (1) with a carbon source, and then calcining again under a protective gas atmosphere...

Embodiment 1

[0053] LiOH, Fe 2 o 3 Add the molar ratio Li:Fe=5.1:1 into deionized water, stir and ultrasonically disperse to form a suspension, and use high-pressure spray drying to evenly spray the suspension onto the manganese prepared in Comparative Example 1. Doped lithium iron phosphate powder LiFe 0.9 mn 0.1 PO 4 Surface, after vacuum drying at 80°C, calcined at 700°C for 10 hours with nitrogen as a protective gas; then added carbon, mixed well, continued to calcined at 450°C for 3 hours with nitrogen as a protective gas, and then cooled naturally to At room temperature, the modified lithium iron phosphate powder is obtained. Among them, the cladding layer includes Li 5 FeO 4 and C, Li in the cladding layer 5 FeO 4 The particle size D50 is 0.01 μm, and the average thickness of the coating layer is 1 μm.

Embodiment 2

[0055] LiOH, MnO 2 Add the molar ratio Li:Mn=6.1:1 into deionized water, stir and ultrasonically disperse to form a suspension, and use high-pressure spray drying to evenly spray the suspension onto the manganese prepared in Comparative Example 1. Doped lithium iron phosphate powder LiFe 0.9 mn 0.1 PO 4 Surface, after vacuum drying at 80°C, calcined at 700°C for 10 hours with nitrogen as a protective gas; then added carbon, mixed well, continued to calcined at 450°C for 3 hours with nitrogen as a protective gas, and then cooled naturally to At room temperature, the modified lithium iron phosphate powder is obtained. Among them, the cladding layer includes Li 6 MnO 4 and C, Li in the cladding layer 6 MnO 4 The particle size D50 is 0.01 μm, and the average thickness of the coating layer is 1 μm.

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Abstract

The invention provides a modified lithium iron phosphate positive electrode material and a preparation method thereof, a positive plate and a lithium secondary battery. The modified lithium iron phosphate positive electrode material comprises a doped lithium iron phosphate core and a coating layer coating the surface of the doped lithium iron phosphate core. The general formula of the doped lithium iron phosphate core is LiFe<alpha>M'<beta>PO<4>, wherein alpha is no less than 0.2 and less than 1; beta is more than 0 and no more than 0.8; and M' is one selected from the group consisting of Ti,Mg, V, Mn, Cr, Zr, Nb and W. The coating layer comprises carbon and Li<x>MNO<y>, wherein x is no less than 2 and no more than 8; a is more than 0 and no more than 1; b is no less than and less than 1; y is no less than 2 and no more than 6; M is one selected from the group consisting of Fe, Co, Mn, Ni, Zr, V, Nb and Mo; and N is one selected from the group consisting of Al, Mg, Ti, Cr, Y, Sr, Si, W, Ga and Zn. The modified lithium iron phosphate positive electrode material of the invention can overcome the problems of poor conductivity and slow diffusion speed of lithium ions of conventional doped lithium iron phosphate positive electrode material, increases the energy density of the lithium secondary battery, and allows the lithium secondary battery to have good rate performance, high-temperature storage performance and high-temperature cycle performance at the same time.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to a modified lithium iron phosphate cathode material and a preparation method thereof, a cathode sheet, and a lithium secondary battery. Background technique [0002] Lithium iron phosphate (LiFePO 4 , referred to as LFP) has been widely used in the field of power and energy storage batteries. It has the advantages of high safety, high cycle life, high quality and low price, and has broad application prospects. However, lithium iron phosphate also has obvious shortcomings, such as Poor electrical conductivity and slow diffusion of lithium ions. At present, the problem of poor conductivity of lithium iron phosphate has been better solved. The usual method is to coat the surface layer of lithium iron phosphate with carbon (C) or other conductive agents. In the actual production process, the conductivity of lithium iron phosphate is improved by adding organic carbon source...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/58H01M4/62H01M10/0525H01M10/42H01M4/136
CPCH01M4/136H01M4/366H01M4/5825H01M4/625H01M10/0525H01M10/4235Y02E60/10
Inventor 郎野彭刚徐磊敏陈雪芹
Owner NINGDE AMPEREX TECH
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