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Preparation method of micro-nano lithium ferric phosphate (LiFePO4) positive electrode material of lithium-ion battery

A lithium-ion battery and lithium iron phosphate technology, which is applied in battery electrodes, nanotechnology, chemical instruments and methods, etc., can solve the problems of unsuitable industrial production of micro-nano lithium iron phosphate materials and long time, and achieve excellent high-rate charge and discharge and low-temperature discharge performance, high specific capacity, and low cost

Active Publication Date: 2011-09-07
ENERGY RES INST OF SHANDONG ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, because the hydrothermal synthesis method needs to react under relatively high pressure and takes a long time, it is not suitable for industrial production of micro-nano lithium iron phosphate materials

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Weigh 40.4g of ferric nitrate, 9.8g of phosphoric acid, 10.2g of lithium acetate and 38.4g of citric acid and dissolve them in 150ml of deionized water; Ammonia solution, adjust the pH value of the solution to 8 to obtain a uniform and stable sol. Add 0.785g of 50% styrene-butadiene rubber emulsion to the sol, transfer the sol to a constant temperature heating stirrer, and stir at a constant temperature for 4 hours at 60°C and a rotation speed of 300rpm to obtain spherical micro-nano phosphoric acid with a secondary particle size of about 6 μm Lithium iron precursor material. Put the spherical micro-nano precursor material into an alumina crucible, heat up to 600°C in a tube furnace at a rate of 200°C / hour, stop heating after 16 hours at a constant temperature, and cool naturally in the furnace to room temperature. During the process, nitrogen gas was continuously fed into the tube furnace, and the gas flow rate was 1 liter / min to obtain spherical micronano lithium iro...

Embodiment 2

[0036] The similarities between this example and Example 1 will not be repeated. The difference is: add 1.57g of 50wt% water-soluble phenolic resin to the sol, heat the stirrer at a constant temperature at 70°C, rotate at 500rpm, and stir at a constant temperature for 3 hours. The secondary particle size of the nano-lithium iron phosphate precursor is about 8 μm, and the heat treatment temperature is 700 ° C, and the temperature is constant for 14 hours. The average particle size of the secondary particles of the micro-nano lithium iron phosphate material is measured to be 8-10 μm, the average particle size of the primary particles is 80 nm, and the tap density of the product is 1.25 g / cm 3 . The battery was assembled using the micro-nano lithium iron phosphate material as the positive electrode and the lithium sheet as the negative electrode. The first discharge specific capacities at 0.1C and 5C rates at room temperature were measured to be 149mAh / g and 128mAh / g, respectivel...

Embodiment 3

[0038] The similarities between this example and Example 1 will not be repeated. The difference is: add 2g of water-soluble starch to the sol, heat the stirrer at a constant temperature at 80°C, rotate at 800rpm, and stir at a constant temperature for 2 hours. Spherical micro-nano lithium iron phosphate precursor The particle size of bulk secondary particles is about 10 μm, and the heat treatment temperature is 800°C, and the temperature is constant for 12h. The average particle size of the secondary particles of the micro-nano lithium iron phosphate material is measured to be 10-15 μm, the average particle size of the primary particles is 100 nm, and the tap density of the product is 1.3 g / cm 3 . The battery was assembled using the micro-nano lithium iron phosphate material as the positive electrode and the lithium sheet as the negative electrode. The first discharge specific capacities at 0.1C and 5C rates at room temperature were measured to be 147mAh / g and 124mAh / g, respec...

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Abstract

The invention discloses a preparation method of a micro-nano lithium ferric phosphate (LiFePO4) positive electrode material of a lithium-ion battery and belongs to the technical field of preparation of an energy source material. The method comprises the following steps of: uniformly mixing a nano-sized precursor material, a lithium source, a carbon source and a proper amount of adhesive; obtaining a spherical LiFePO4 precursor material with micron-sized secondary particles by a dry mixing granulation process; and drying and performing high-temperature thermal treatment to obtain a spherical micro-nano LiFePO4 material, wherein the spherical micro-nano LiFePO4 material has the characteristics of high tap density, good processing performance, large specific surface area and porous property;and the battery which is assembled by the material is characterized by low temperature, good high-multiplying-power charging and discharging performance and high specific capacity. LiFePO4 powder which is prepared by the method consists of secondary micron spherical particles which are obtained by assembling primary nano particles, wherein the particle size of the primary particles is about 30 to100 nm; the mean particle size of the secondary particles is 1 to 20 mu m; the tap density can be equal to 1.2 to 1.5 g / cm<2>; discharging specific capacities of 0.1 C and 5 C at room temperature canbe equal to 145 to 152 milliampere hour per gram (mAh / g) and 120 to 130 mAh / g respectively; and the retention rate of the discharging specific capacity of 0.5 C at the temperature of 20 DEG C below zero is equal to 70 percent.

Description

technical field [0001] The invention belongs to the technical field of energy materials, and in particular relates to a preparation method of micronano lithium iron phosphate, a cathode material of a lithium ion battery. Background technique [0002] Lithium iron phosphate (LiFePO) with orthorhombic olivine structure 4 ) has the following advantages: no precious elements, cheap raw materials, extremely rich resources; moderate working voltage (3.4V); good platform characteristics, extremely stable voltage (comparable to regulated power supply); large theoretical capacity (170mAh / g) Stable structure and excellent safety performance (O and P are firmly combined with strong covalent bonds, making it difficult for the material to be decomposed by oxygen evolution); high temperature performance and cycle performance are good; the volume shrinks during charging, and the volume effect when combined with carbon negative electrode materials Good; good compatibility with most electro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/45B82Y40/00H01M4/1397
CPCY02E60/12Y02E60/122Y02E60/10
Inventor 杨改蔡飞鹏许敏孙立
Owner ENERGY RES INST OF SHANDONG ACAD OF SCI
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