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Preparation method of lithium iron phosphate/carbon composite material

A carbon composite material, lithium iron phosphate technology, applied in electrical components, battery electrodes, circuits, etc., can solve the problems of small tap density, low battery volume specific capacity, and large pollution, and achieve small particle size and capacity retention High efficiency and low energy consumption

Inactive Publication Date: 2011-11-16
DALIAN JIAOTONG UNIVERSITY
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Nitric acid raw materials can produce nitrogen oxides during calcination and synthesis, causing great pollution
For this reason, Sun Y and others synthesized porous iron phosphate by co-precipitation method as iron source, lithium hydroxide as lithium source, citric acid as chelating agent, polyethylene glycol as carbon source, and synthesized porous Lithium iron phosphate / carbon cathode material (Sun Y et al, Synthesis of LiFePO 4 cathode materials by a chemical method, Advanced materials Research, 2011, 197-198: 1049-1052), relatively environmentally friendly, but the porous lithium iron phosphate / carbon material leads to too small tap density, and the volume specific capacity of the battery is low

Method used

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  • Preparation method of lithium iron phosphate/carbon composite material
  • Preparation method of lithium iron phosphate/carbon composite material
  • Preparation method of lithium iron phosphate/carbon composite material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] 83.40g FeSO 4 ·7H 2 O and 34.80 g H3 PO 4 Add it into 150ml of deionized water, stir until completely dissolved, then add 18.00g of 30wt% H 2 o 2 , stir to make it completely react, add about 321ml of 2M / L ammonia water dropwise to the solution, the pH is about 3.65, continue to stir until the pH value is basically stable. Filtrate, wash the obtained precipitate, and dry at 80°C to obtain the precursor iron phosphate.

[0035] Weigh 12.60g of citric acid and 11.34g of oxalic acid, dissolve them in 90g of deionized water, weigh 15.12g of LiOH·H 2 O was put into the acid solution, and after the reaction was complete, pour 45.26g of synthetic ferric phosphate into it, mix and stir for 15 hours. The reacted slurry was spray-dried to obtain gel particles, which were then calcined at 650°C under a high-purity argon atmosphere, kept for 6 hours, and cooled to room temperature with the furnace to obtain a lithium iron phosphate / carbon composite material.

[0036] The carb...

Embodiment 2

[0039] 13.91gFeSO 4 ·7H 2 O and 5.76g H 3 PO 4 Add it into 25ml of deionized water, stir until completely dissolved, then add 3.00g of 30wt% H 2 o 2 , stir to make it react completely, add 55ml of 2M / L ammonia water dropwise to the solution, the pH is 3.50, continue to stir until the pH value is basically stable. Filtrate, wash the resulting precipitate, and dry at 75°C to obtain the precursor iron phosphate.

[0040] Weigh 5.56g of citric acid and 2.52g of oxalic acid, dissolve them in 30g of deionized water, weigh 5.04g of LiOH·H 2 O was put into the acid solution, after the reaction was complete, pour 22.42g of synthesized ferric phosphate and mechanically stir for 15 hours. The reacted slurry was spray-dried to obtain gel particles, which were then calcined at 650°C under a high-purity argon atmosphere, kept for 6 hours, and cooled to room temperature with the furnace to obtain a lithium iron phosphate / carbon composite material.

[0041] The carbon content in the ma...

Embodiment 3

[0044] 27.80gFeSO 4 ·7H 2 O, 11.60gH 3 PO 4 Add 50ml of deionized water, stir until completely dissolved, then add 6.00g of 30wt% H 2 o 2 , Stir to make it completely react, add 107ml of 2M / L ammonia water dropwise to the solution, control the pH to about 3.38, continue to stir until the pH value is basically stable. Filtrate, wash the resulting precipitate, and dry at 75°C to obtain the precursor iron phosphate.

[0045] Weigh 5.04g of citric acid and 3.02g of oxalic acid, dissolve them in 30g of deionized water, weigh 5.04g of LiOH·H 2 O was put into the acid solution, and after the reaction was complete, 22.44 g of synthetic ferric phosphate ball mill was added and mixed for 10 hours. The slurry was spray-dried to obtain gel particles, which were then calcined at 700°C under a high-purity nitrogen atmosphere, kept for 6 hours, and cooled to room temperature with the furnace to obtain a lithium iron phosphate / carbon composite material.

[0046] The carbon content in t...

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Abstract

The invention relates to a preparation method of a lithium iron phosphate / carbon composite material. The preparation method comprises the following steps: preparing amorphous iron phosphate through a coprecipitation method from a soluble ferrous iron source, a phosphorus source and an oxidant used as raw materials, and synthesizing the lithium iron phosphate / carbon cathode material on the basis of amorphous iron phosphate through a gel method by using oxalic acid and citric acid as carbon sources and lithium hydroxide as a lithium source, wherein by adjusting the ratio of the oxalic acid to the citric acid, the carbon content can be controlled, and ion doping can be easily carried out. The prepared lithium iron phosphate has the advantages of small particle size and narrow particle size distribution, thus reducing the ion diffusion path and maintaining high capacity and good rate performance of the product. In the preparation method provided by the invention, inexpensive ferrous sulfate is used as a raw material to synthesize amorphous ferric phosphate without preventing Fe<2+> from oxidation, thereby simplifying the process; ammonium salt waste liquid can be recycled as fertilizer, thereby reducing the cost; and water is used as the solvent in the preparation process, thereby generating no harmful gas. Thus, the preparation method is environmentally friendly, low in energy consumption, low in cost and suitable for industrial mass production.

Description

technical field [0001] The invention relates to a preparation method of lithium iron phosphate / carbon composite material, which can be used as positive electrode material of lithium ion battery. It belongs to the technical field of new energy materials. Background technique [0002] Olivine lithium iron phosphate and LiCoO 2 Compared with other positive electrode materials, it has the advantages of long service life, low raw material cost, high thermal stability, good safety and environmental friendliness, making it one of the most potential positive electrode materials. Through research on the modification of lithium iron phosphate, such as adding carbon to increase electronic conductivity and ion doping, reducing particle size to increase lithium ion conductivity, etc., the low-temperature conductivity of lithium iron phosphate has been improved, and the performance has reached practicality. s level. [0003] The preparation method of lithium iron phosphate can be divid...

Claims

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Application Information

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IPC IPC(8): H01M4/1397
CPCY02E60/12Y02E60/122Y02E60/10
Inventor 李国军赵秀娟任瑞铭孙苑景海力杨铭
Owner DALIAN JIAOTONG UNIVERSITY
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