Method for preparing cathode material for LiVPO4F lithium-ion batteries by means of double-layer carbon coating

A lithium ion battery, lithium vanadium fluorophosphate technology, applied in battery electrodes, positive electrodes, secondary batteries, etc., can solve problems to be improved, achieve ultra-stable cycle performance, easy operation, and reduce the effect of grain size

Inactive Publication Date: 2018-10-16
XI AN JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] But LiVPO 4 The cycle performance and rate performance of lithium-ion battery cathode materials still need to be improved

Method used

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  • Method for preparing cathode material for LiVPO4F lithium-ion batteries by means of double-layer carbon coating
  • Method for preparing cathode material for LiVPO4F lithium-ion batteries by means of double-layer carbon coating
  • Method for preparing cathode material for LiVPO4F lithium-ion batteries by means of double-layer carbon coating

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] 1) Mix vanadium salt, carbon source and phosphate source uniformly according to the ratio of V:P molar ratio=1:1, C:P molar ratio=1.5:1, heat treatment at 600°C for 12h under nitrogen atmosphere, then pulverize and grind, Obtain mesophase product;

[0031] 2) Mix the mesophase product, lithium fluoride and carbon source uniformly according to the ratio of Li:V:P:F molar ratio = 1:1:1:1, C:P molar ratio = 0.02:1, and then heat-treat at 800°C 1h, then pulverize and grind, and obtain double-layer carbon coating after sieving to prepare LiVPO 4 F Lithium-ion battery cathode material.

[0032] Vanadium salt is V 2 o 5 .

[0033] The carbon source in step 1) is citric acid.

[0034] The carbon source in step 2) is sucrose.

[0035] The phosphate source is H 3 PO 4 .

Embodiment 2

[0037] 1) Mix vanadium salt, carbon source and phosphate source uniformly according to the ratio of V:P molar ratio=1:1, C:P molar ratio=1.5:1, heat treatment at 800°C for 1h under nitrogen atmosphere, then pulverize and grind, Obtain mesophase product;

[0038] 2) Mix the mesophase product, lithium fluoride and carbon source uniformly according to Li:V:P:F molar ratio = 1:1:1:1, C:P molar ratio = 0.1:1, and then heat-treat at 700°C 3h, then pulverize and grind, and obtain double-layer carbon coating after sieving to prepare LiVPO 4 F Lithium-ion battery cathode material.

[0039] Vanadium salt is V 2 o 3 .

[0040] The carbon source in step 1) is sucrose.

[0041] The carbon source in step 2) is VC.

[0042] Phosphate source is NH 4 h 2 PO 4 .

Embodiment 3

[0044] 1) Mix vanadium salt, carbon source and phosphate source uniformly according to the ratio of V:P molar ratio=1:1, C:P molar ratio=1.5:1, heat treatment at 700°C for 7h under nitrogen atmosphere, then pulverize and grind, Obtain mesophase product;

[0045] 2) Mix the mesophase product, lithium fluoride and carbon source uniformly according to Li:V:P:F molar ratio = 1:1:1:1, C:P molar ratio = 0.15:1, and then heat-treat at 600°C 7h, then pulverize and grind, and obtain double-layer carbon coating after sieving to prepare LiVPO 4 F Lithium-ion battery cathode material.

[0046] Vanadium salt is NH 4 VO 3 .

[0047] The carbon source in step 1) is VC.

[0048] The carbon source in step 2) is glucose.

[0049] The phosphate source is (NH 4 ) 2 HPO 4 .

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Abstract

The invention relates to a method for preparing a cathode material for LiVPO4F lithium-ion batteries by means of double-layer carbon coating. The method comprises the following steps: uniformly mixingvanadium salt, a carbon source and a phosphate source according to a molar ratio of V to P being equal to 1 to 1 and a molar ratio of C to P being equal to 1.5 to 1, carrying out heat treatment in aprotective atmosphere, and then pulverizing and grinding to obtain a mesophase product; evenly mixing the mesophase product, lithium fluoride and the carbon source according to a molar ratio of Li toV to P to F being equal to 1 to 1 to 1 to 1 and a molar ratio of C to P being equal to (0.02-0.2) to 1, and then carrying out heat treatment at 500-800 DEG C for 1-12h. By means of control of phase composition and ratio in the two steps of synthesis, the method can control the carbon content, coating layers and layer thickness of the final product. Good carbon coating situation can improve the electronic conductivity of the material and control the sizes of particles, so that the modified LiVPO4F material can achieve ultra-stable cycle performance and excellent rate capability.

Description

technical field [0001] The invention relates to a novel carbon coating method for lithium-ion battery cathode materials, in particular to a preparation method for preparing vanadium phosphate lithium lithium-ion battery cathode materials by double-layer carbon coating. Background technique [0002] As an important part of lithium-ion batteries, the performance of cathode active materials has become an important bottleneck of lithium-ion batteries. Conventional commercial Li-ion batteries use LiCoO 2 / Graphite system, due to problems such as insufficient performance, poor safety, high cost and environmental pollution, can no longer meet people's requirements. LiVPO, a novel polyanion cathode material, lithium vanadium fluorophosphate 4 F not only inherits the advantages of the phosphate system, but also has the advantages of high voltage platform, high energy density, and stable structure. However, the rate and cycle performance of the material at high current density are ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/58H01M4/62H01M10/0525
CPCH01M4/366H01M4/5825H01M4/625H01M10/0525H01M2004/021H01M2004/028Y02E60/10
Inventor 徐友龙邬杰兵薛旭张晓娜滕峰
Owner XI AN JIAOTONG UNIV
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