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A kind of high-performance lithium iron phosphate composite material and preparation method thereof

A lithium iron phosphate, composite material technology, applied in the direction of nanotechnology, nanotechnology, structural parts, etc. for materials and surface science, can solve the problems of reducing reaction temperature, shortening reaction time, low specific capacity, etc., to achieve chemical stability High performance, high mechanical strength, and the effect of improving specific capacity

Active Publication Date: 2021-04-06
SHANDONG FENGYUAN CHEM CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the ionic conductivity and electronic conductivity of lithium iron phosphate are both low, so it is only suitable for charging and discharging at low current density, and the specific capacity decreases when charging and discharging at high rates, which limits the application of this material. Low, limiting its promotion in the field of high specific energy density lithium-ion batteries
Although a lot of research has been done on the modification of lithium iron phosphate at home and abroad to improve the conductivity of lithium iron phosphate, mainly including the preparation of nano-scale LiFePO 4 , carbon coating, metal ion doping, etc., and carbon coating is the most commonly used and simple method, that is, mainly by coating glucose, sucrose and other carbon source organic substances on the surface of lithium iron phosphate to improve its conductivity, such as the patent ( 200610035986.1) discloses a method for high-pressure solid phase synthesis of lithium iron phosphate cathode material, which mainly mixes lithium salt, iron salt, and phosphate according to the stoichiometric ratio of lithium, iron, and phosphorus in a ratio of 1:1:1 Uniformity, ball milling for 6-24 hours to obtain the precursor, and coating carbon material on its surface, the inventive method is simple in process, rich in raw material sources, the use of high-pressure atmosphere can shorten the reaction time and lower the reaction temperature, the obtained product has high actual capacity and excellent cycle performance. However, the low conductivity of the surface-coated carbon material affects the gram capacity and rate performance of the material.
The patent (CN1958441A) discloses a preparation method of lithium iron phosphate powder, which is mainly through the preparation of lithium salt, iron salt, phosphorus salt, a small amount of carbon organic precursors and doped metal ions according to the ratio and high performance Ball milling mixed and prepared high-performance lithium iron phosphate materials, but the poor doping uniformity of metal ions and the gradient difference between the metal ion and lithium iron phosphate caused its performance to not be fully exerted, and the surface-coated carbon material and metal The poor bonding force and poor consistency will affect the comprehensive performance of the material

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  • A kind of high-performance lithium iron phosphate composite material and preparation method thereof
  • A kind of high-performance lithium iron phosphate composite material and preparation method thereof
  • A kind of high-performance lithium iron phosphate composite material and preparation method thereof

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preparation example Construction

[0023] The preparation of lithium iron phosphate precursor in the embodiment of the present invention adopts the following methods:

[0024] Using lithium dihydrogen phosphate LiH 2 PO 4 , Fe2O3 2 o 3 , Magnesium hydroxide Mg(OH) 2 As a raw material, according to the atomic ratio Li:Fe:Mg:P=1:0.99:0.01:1, 31179g LiH 2 PO 4 , 23715gFe 2 o 3 , 174.9gMg(OH) 2 , 3420g of nano zirconia balls were added to the ball mill; then 70kg of deionized water was added, and wet milled for 12 hours; after that, the above slurry was spray-dried so that the inlet temperature of the spray dryer was 200-350°C, and the outlet temperature was not lower than 120°C. Spherical lithium iron phosphate material body.

Embodiment 1

[0026] Firstly, by the particle injection method, it is carried out under an oxygen atmosphere, the gas flow rate is 30 sccm, and the air pressure is 3×10 -4 Under Pa, adjust the injection temperature to 300°C, inject nano-titanium with a mass of 5g and a diameter of 200nm into 100g of lithium iron phosphate body, and then crush and classify to obtain lithium iron phosphate precursor A;

[0027] At the same time, 5.8g of nickel catalyst with a particle size of 100nm and 96g of citric acid were added to 914ml of deionized water to prepare a mixed solution with a concentration of 10% (solution B for short).

[0028] Then add 10g of precursor material A to 200ml of solution B, soak for 12 hours at a temperature of 60°C, and then obtain material C by vacuum drying and crushing;

[0029] Then put the material C into the middle of the tube-type resistance furnace, and raise the temperature under the protection of argon; heat it up to 800°C for 120 minutes, change to hydrogen for 120...

Embodiment 2

[0031] Firstly, by the particle injection method, it is carried out under an ammonia atmosphere, the gas flow rate is 5 sccm, and the air pressure is 2×10 -4 Under Pa, adjust the injection temperature to 100°C, inject nano-vanadium with a mass of 5g and a diameter of 100nm into 100g of lithium iron phosphate body, and then crush and classify to obtain lithium iron phosphate precursor A;

[0032] At the same time, 5.9g of cobalt catalyst with a particle size of 10nm and 19.2g of citric acid were added to 100ml of deionized water to prepare a mixed solution with a concentration of 20% (solution B for short).

[0033] Then add 5g of precursor material A to 200ml of solution B, soak for 24h at a temperature of 20°C, and then obtain material C by vacuum drying and crushing;

[0034] Then put the material C into the middle of the tubular resistance furnace, and raise the temperature under the protection of argon; heat it up to 600°C for 2 hours, change to hydrogen for 60 minutes, th...

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Abstract

The invention belongs to the field of preparation of lithium ion battery materials, in particular to a high-performance lithium iron phosphate composite material and a preparation method thereof. Specifically, nanometer metal or nanometer metal compound material is implanted into iron phosphate through high-speed particle beam bombardment. In the surface layer of lithium, it is then soaked in a catalyst solution, and then graphene is grown on its surface by chemical vapor deposition method to improve the conductivity and rate capability of the material. The prepared material grows graphene on the surface of lithium iron phosphate through chemical bonds, which significantly improves the compaction density and electrical conductivity of the material, and uses the particle implantation method to precisely control the uniformity, depth and depth of the doped metal on the surface of the material. quantity, improve the specific capacity of its materials, and be applied to high specific energy density lithium-ion batteries.

Description

technical field [0001] The invention belongs to the field of lithium ion battery materials, and in particular relates to a high-performance lithium iron phosphate composite material and a preparation method thereof. Background technique [0002] Lithium iron phosphate (LiFePO 4 ) Theoretical capacity is 170mAh / g, the reversible charging specific capacity is high, and at the same time, it has the advantages of wide source of raw materials, low pollution, good safety, long cycle life, etc. Material. However, the ionic conductivity and electronic conductivity of lithium iron phosphate are both low, so it is only suitable for charging and discharging at low current density, and the specific capacity decreases when charging and discharging at high rates, which limits the application of this material. Low, which limits its promotion in the field of high specific energy density lithium-ion batteries. Although a lot of research has been done on the modification of lithium iron ph...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/58H01M4/62H01M10/0525B82Y30/00
CPCB82Y30/00H01M4/366H01M4/5825H01M4/625H01M4/626H01M10/0525Y02E60/10
Inventor 李桂臣朱涛
Owner SHANDONG FENGYUAN CHEM CO LTD