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Lithium iron phosphate composite electrode with metal oxide coating layer on surface

A technology of oxide coating and lithium iron phosphate, which is applied in electrode manufacturing, battery electrodes, circuits, etc., can solve problems affecting the structural stability of lithium iron phosphate, increase the difficulty of process processing, and increase the hygroscopicity of materials, so as to achieve heat suppression Effects of runaway reaction, reduction of dissolution, and inhibition of corrosion

Inactive Publication Date: 2018-01-26
SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Doping and modification can significantly improve the electronic conductivity of lithium iron phosphate and improve the high-rate charging performance of the material, but the surface coating process is generally more complicated and will significantly reduce the tap density of the material, and the doping of metal ions is bound to It will affect the structural stability of lithium iron phosphate itself, and then affect its cycle performance; fine particles can significantly improve the ionic conductivity and electronic conductivity of the electrode, but in the actual processing process, due to the increase in hygroscopicity of the material and difficulty in dispersing, the process has been improved. Processing difficulty

Method used

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  • Lithium iron phosphate composite electrode with metal oxide coating layer on surface
  • Lithium iron phosphate composite electrode with metal oxide coating layer on surface
  • Lithium iron phosphate composite electrode with metal oxide coating layer on surface

Examples

Experimental program
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Effect test

Embodiment 1

[0026] Lithium iron phosphate, acetylene black and polyvinylidene fluoride (PVDF) are evenly mixed into a slurry, and the slurry is evenly coated on the aluminum current collector with an automatic coating machine, dried, and rolled to prepare a lithium iron phosphate electrode piece. Among them, the mass ratio of lithium iron phosphate: acetylene black: PVDF is 85:7:8, and the thickness of the lithium iron phosphate pole piece after rolling is about 55 μm (collector fluid).

[0027] Add 10g of Al with particle size D50=300nm in 100g of deionized water 2 o 3 Granules and 1g polyvinylpyrrolidone (PVP), after mixing evenly, use a planetary ball mill to stir and disperse for 2 hours at a speed of 400rpm, then add 12g of 50% solid content of styrene-butadiene rubber (SBR) and 1.5g of sodium carboxymethylcellulose (CMC) (actual binder content 7.5g), continue to adopt planetary ball mill to continue to disperse 12h with the rotating speed of 400rpm, obtain the evenly dispersed Al ...

Embodiment 2

[0034] Add 15g of SiO with particle size D50=50nm in 150g deionized water 2 Granules and 1g of polyethylene glycol (PEG), mixed evenly, stirred and dispersed with a planetary ball mill at a speed of 400rpm for 24h, then added 60g of sodium alginate aqueous solution (sodium alginate: water = 1:5wt%) (actual binder content 10g), continue to use the planetary ball mill to stir and disperse at a speed of 600rpm for 12h to obtain evenly dispersed SiO 2 slurry. The resulting slurry was coated on the surface of the lithium iron phosphate pole piece by spin coating. The spin coating time was 180s, and the thickness of the deposited layer was about 3 μm. After natural drying at 60°C, it was dried in vacuum at 120°C for 12h to obtain the surface SiO 2 Coated lithium iron phosphate composite electrode, the thickness of the pole piece is increased by about 1 μm, SiO 2 It accounts for about 0.5% of the pole piece weight.

Embodiment 3

[0036] Add 15g of Al with particle diameter D50=500nm in 100g of ethanol 2 o 3 Particles and 1g of PVP, after mixing evenly, use a planetary ball mill to stir and disperse at 200rpm for 2 hours, then add 55g of polyvinylidene fluoride (PVDF) in acetone solution (PVDF: acetone = 1:10wt%) (the actual binder quality is 5g), Continue to use the planetary ball mill to stir and disperse at a speed of 300rpm for 12h to obtain evenly dispersed Al 2 o 3 slurry. After the obtained slurry was heated to 40°C, it was coated on the surface of the lithium iron phosphate pole piece by the dip coating method. During the dip coating, the dip coating thickness of the electrode was controlled to be 120 μm (the thickness of the pole piece increased by about 9.2 μm after dip coating and drying, and the quality increased. about 4.7%), after natural drying at 60°C, vacuum drying at 120°C for 12 hours to obtain surface Al 2 o 3 Coated lithium iron phosphate composite electrode.

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Abstract

The invention relates to a lithium iron phosphate composite electrode with a metal oxide coating layer on a surface. The lithium iron phosphate composite electrode comprises a lithium iron phosphate pole plate and the coating layer, wherein the coating layer is formed by coating a metal oxide, a dispersing agent and a binding agent on the lithium iron phosphate pole plate, the grain size of the metal oxide is 50-500 nanometers, the thickness of the coating layer is 1-10 micrometers, and the mass of the coating layer accounts for 0.1-5% of the total mass of the composite electrode. The invention also relates to a preparation method of the lithium iron phosphate composite electrode. The preparation method comprises the following steps of S1, providing the lithium iron phosphate pole plate; S2, uniformly dispersing the metal oxide and the binding agent in a solvent by the dispersing agent to form paste; and S3, coating the paste on an outer surface of the lithium iron phosphate pole plateand performing drying to obtain the lithium iron phosphate composite electrode. The lithium iron phosphate composite electrode with the metal oxide coating layer on the surface has favorable cycle property and high safety.

Description

technical field [0001] The invention relates to a positive electrode material of a lithium ion battery, in particular to a lithium iron phosphate composite electrode with a metal oxide coating on the surface. Background technique [0002] As a new type of energy storage device, lithium-ion batteries have been widely used in the field of power and energy storage, which also puts forward higher requirements for the specific capacity, stability and safety of lithium-ion batteries. Lithium iron phosphate cathode material (LiFePO 4 ), non-toxic, environmentally friendly, rich sources of raw materials, theoretical specific capacity of 170mA / g, voltage platform of 3.5V; and because LiFePO 4 FePO obtained after delithiation 4 It has the same space group and crystal structure (there is a slight difference in the lattice constant), and the volume is only reduced by 6.81%, which will not cause deformation and breakage of the particles, and the electrical contact between particles and...

Claims

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Application Information

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IPC IPC(8): H01M4/04H01M4/136H01M4/1397H01M4/36H01M4/58H01M4/62H01M10/0525
CPCY02E60/10
Inventor 王倩杨成云罗海波张建谢晓华夏保佳
Owner SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
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