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Method for synthesizing lithium iron phosphate anode material at low cost

A technology of lithium iron phosphate and positive electrode materials, which is applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., and can solve problems such as difficult to mix the stoichiometric ratio of the three raw materials uniformly, difficulty in lithium iron phosphate, and low tap density , to achieve the effect of improving electrochemical performance, reducing primary particle size, and small primary particle size

Active Publication Date: 2011-02-16
ZHEJIANG RICHPOWER TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, lithium iron phosphate has the following obvious disadvantages: (1) Fe 2+ easily oxidized to Fe 3+ , it is not easy to obtain pure phase lithium iron phosphate; (2) Li + The diffusion rate in lithium iron phosphate is low, resulting in low utilization of active materials; (3) the low conductivity of lithium iron phosphate itself leads to poor high rate charge and discharge performance
In addition, it contains crystal water, which is not easy to measure accurately
The instability of raw materials will have a serious impact on product quality
Due to technical and equipment limitations, it is difficult to mix the three raw materials evenly according to the stoichiometric ratio, which affects the batch stability of the product
[0006] (2) Due to the large amount of gas generated during the production process, the solid loss rate is greater than 50%, the product structure is fluffy, and the tap density is extremely low (only 0.5g / cm 3 )
However, due to lithium dihydrogen phosphate (LiH 2 PO 4 ) The price is high, and its proportion in the cost of raw materials exceeds 60%, resulting in the price of lithium iron phosphate not reaching a reasonable level

Method used

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  • Method for synthesizing lithium iron phosphate anode material at low cost
  • Method for synthesizing lithium iron phosphate anode material at low cost
  • Method for synthesizing lithium iron phosphate anode material at low cost

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Take by weighing 12000g deionized water and place in the acid-proof reaction kettle, under the situation of stirring, slowly pour into 5000g H 3 PO 4 (mass fraction 85%), diluted H 3 PO 4 The mass fraction is 25%. Weigh 1820g LiOH·H 2 O was slowly added to the above solution and stirred for 30 min to obtain a colorless solution. Transfer all the colorless solution to the stirring ball mill, add 3469g Fe 2 o 3 , 170g polyvinylpyrrolidone (PVP), 374g acetylene black. Grind in a stirring ball mill for 3 hours at 300 rpm to obtain a brown-red suspension, namely the precursor slurry. The precursor slurry was transported to the atomizing disc of the spray dryer at a flow rate of 0.6L / min by a metering pump under constant stirring, the inlet temperature was set at 300°C, and the outlet temperature was set at 120°C. Collector can get brownish red precursor powder. Put the precursor powder into a sagger, place it in a rotary furnace with high-purity nitrogen protection ...

Embodiment 2

[0031] Take by weighing 10000g deionized water and place it in an acid-resistant reaction kettle, and slowly pour 5000g H 3 PO 4 (mass fraction 85%), diluted H 3 PO 4 The quality fraction of is 28.3%. Weigh 1820g LiOH·H 2 O was slowly added to the above solution and stirred for 30 min to obtain a colorless solution. Transfer all the colorless solution to the stirring ball mill, add 3347g Fe 3 o 4 , 204g soluble starch, 272g superconducting carbon black. Grinding with a stirring ball mill at 200 rpm for 4 hours to obtain a black suspension, namely the precursor slurry. The precursor slurry was transported to the atomizing disc of the spray dryer at a flow rate of 0.4L / min by a metering pump under constant stirring, the inlet temperature was set at 280°C, and the outlet temperature was set at 110°C. The collector yields a black precursor powder. Put the precursor powder into a sagger, place it in a rotary furnace with high-purity nitrogen protection (gas flow rate is 2L...

Embodiment 3

[0033] Take by weighing 11000g deionized water and place in the acid-resistant reaction kettle, under the situation of stirring, slowly pour into 5000g H 3 PO 4 (mass fraction 85%), diluted H 3 PO 4 The quality fraction of is 26.6%. Weigh 1602g Li 2 CO 3 Slowly added to the above solution and stirred for 30min to obtain a colorless solution. Transfer all the colorless solution to the stirring ball mill, add 3469g Fe 2 o 3 , 136g polyvinyl alcohol (PVA), 374g acetylene black. Grind in a stirring ball mill at 300 rpm for 3 hours to obtain a brownish-red suspension, namely the precursor slurry. The precursor slurry was transported to the atomizing disc of the spray dryer at a flow rate of 0.4L / min by a metering pump under constant stirring, the inlet temperature was set at 320°C, and the outlet temperature was set at 135°C. Collector can get brownish red precursor powder. The precursor powder was put into a sagger, placed in a rotary furnace with high-purity nitrogen pr...

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Abstract

The invention discloses a method for synthesizing lithium iron phosphate anode material at low cost, which belongs to the technical field of energy materials. The method comprises the following steps: preparing a solution containing equimolar Li+ and H2PO4- from lithium salt and phosphoric acid directly; adding an iron source, an organic carbon source and an inorganic carbon source into the solution, and grinding the mixture in a stirring ball mill to obtain precursor slurry; spraying the precursor slurry, drying and granulating to obtain spherical precursor powder; and sintering the precursor powder in a rotary furnace under the protection of inert gas, and naturally cooling to the room temperature to obtain the product. As the solution containing equimolar Li+ and H2PO4- is directly prepared, the steps of reaction, purification, re-crystallization, drying and the like during the manufacturing of lithium dihydrogen phosphate are saved, and the cost of the raw materials is reduced by over 20%. Moreover, by adopting of a joint cladding means combining organic carbon and inorganic carbon, the method reduces the primary particle size (about 200 nm) of the lithium iron phosphate powder, improves the conductivity of the material and greatly enhances the electrochemical performance of the product.

Description

technical field [0001] The invention belongs to the technical field of energy material preparation, and in particular relates to a low-cost method for synthesizing lithium iron phosphate cathode materials for lithium ion batteries. Background technique [0002] At present, great progress has been made in the negative electrode materials and electrolyte systems of lithium-ion batteries, while the development of positive electrode materials is relatively lagging behind, which seriously affects the powerization process of lithium-ion batteries. Its main performance is as follows: First, safety issues, the only commercial cathode material LiCoO 2 It is not stable enough, and it will decompose when overcharged and overheated, which may cause the battery to explode, which is especially prominent in power batteries; the second is the cost issue. The global cobalt reserves are limited, so the price is high, which limits the LiCoO. 2 Application in power batteries; The third is envi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/45
Inventor 唐昌平郑金龙蔡静周勤女陈耿斌胡大伟
Owner ZHEJIANG RICHPOWER TECH
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