Method for making ferrous lithium phosphate/carbon compound material of high active disorderly ferric phosphate

A technology of lithium ferrous phosphate and carbon composite materials, which is applied in the fields of phosphorus compounds, chemical instruments and methods, and inorganic chemistry. Capacity, the effect of avoiding product impurity

Inactive Publication Date: 2008-08-06
NORTHEAST NORMAL UNIVERSITY
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  • Abstract
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AI Technical Summary

Problems solved by technology

Triclinic nanoscale iron phosphate due to Fe 3+ /Fe 2+ The existence of /Fe redox pair has a high specific capacity as the negative electrode material of lithium-ion batteries; the trigonal iron phosphate has the most stable structure under normal pressure, and the metastable orthorhombic (Pnma) Iron phosphate transforms into this structure at 700 °C, which can be obtained by liquid-phase method or hydrothermal synthesis of precursors and high-temperature sintering. However, because the structure is too stable, only 1 ) and orthorhombic (space group Pbca) crystal system iron phosphate can be synthesized by hydrothermal method, because it can form hexagonal lithium ion channels, about 0.2Li/Fe can be reversibly deintercalated during charge and discharge, and the electric The chemical activity is higher than the ferric

Method used

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  • Method for making ferrous lithium phosphate/carbon compound material of high active disorderly ferric phosphate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Preparation of ferric phosphate: mix the ferrous phosphate with a concentration of 0.1 mol / L and phosphoric acid solution in equal volume, add hydrogen peroxide solution with a mass concentration of 20% under stirring, adjust the pH to 3, and after 12 hours of reaction, suction filter , Washing, drying to obtain highly active disordered iron phosphate (FePO 4 ·2H 2 O).

[0025] Weigh iron phosphate (FePO 4 ·2H 2 O) 33.66g, lithium hydroxide (LiOH·H 2 O) 7.938g, 2.844g anhydrous glucose, add ethanol, ball mill at 400r / min for 10 hours, spray dry, program the temperature in a nitrogen atmosphere, increase to 550°C at 5°C / min, keep it warm for 12h, natural After cooling, a lithium iron phosphate / carbon composite material is obtained.

[0026] At room temperature, with a lithium sheet as the negative electrode, the discharge capacity curve of the lithium iron phosphate / carbon composite material at various rates is shown in the accompanying drawings.

Embodiment 2

[0028] The preparation of iron phosphate is the same as in Example 1. Combine 1mol phenol with excess formaldehyde in NH 4 Under OH catalysis, react at 50-90°C for 10 hours, then adjust the pH value to neutral with hydrochloric acid, and continue to react for 5 hours to obtain a resol phenolic resin. Weigh iron phosphate (FePO 4 ·2H 2 O) 33.66g, lithium hydroxide (LiOH·H 2O) 7.56g, 4.266g phenolic resin, add anhydrous ethanol, ball mill at 400r / min for 10 hours, spray dry, program temperature rise in nitrogen atmosphere, increase to 700°C at 5°C / min, keep it warm for 8 hours , Natural cooling, to obtain lithium iron phosphate / carbon composite material. With a lithium sheet as the negative electrode, the discharge capacity of the lithium iron phosphate / carbon composite material can reach 138mAh / g at a rate of 1C.

Embodiment 3

[0030] Preparation of iron phosphate: mix 0.1mol / L ferrous sulfate and ammonium monohydrogen phosphate solution in equal volume, add 15% hydrogen peroxide solution with mass concentration under stirring, adjust the pH to 4, and react for 18 hours , Suction filtration, washing, drying to obtain highly active disordered iron phosphate (FePO 4 ·2H 2 O).

[0031] Weigh iron phosphate (FePO 4 ·2H 2 O) 33.66g, lithium carbonate (Li 2 CO 3 ) 13.32g, super P2.2752g, add distilled water, ball mill at 400r / min for 10 hours, spray dry, program temperature rise in nitrogen atmosphere, increase to 450°C at 5°C / min, keep for 12 hours, cool naturally , To obtain lithium iron phosphate / carbon composite material. With a lithium sheet as a negative electrode, the discharge capacity of the lithium iron phosphate / carbon composite material can reach 132 mAh / g at a rate of 1C.

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Abstract

The present invention belongs to energy material, and in particular relates to a method of using high-activity disordered iron phosphate to prepare ferrous phosphate lithium/carbon composite material. A ferrous iron source is mixed with phosphorus source solution according to stoichiometric ratio, has hydrogen peroxide added in, has pH value controlled and is stirred so as to prepare high-activity disordered iron phosphate. iron phosphate, a lithium source and a carbon source are mixed pro rata, ball-milled uniformly, spray-dried and treated via high temperature under protective atmosphere, so as to obtain high specific capacity ferrous phosphate lithium/carbon composite material of which the average particle diameter is 200-500nm, 0.25C rate specific discharge capacity reaches 145-150mAh/g, 1C rate specific discharge capacity reaches 130-140mAh/g, and 5C rate specific discharge capacity reaches 105-110mAh/g. The method is low in cost and simple in process. Prepared material is good in electrochemical performance and especially excellent in rate performance, which is applicable to battery anode material of electric vehicles and other large-scale mobile devices.

Description

Technical field [0001] The invention belongs to the technical field of energy materials. In particular, it relates to a method for preparing lithium iron phosphate / carbon composite material with high activity disordered iron phosphate, which can be used as a positive electrode material of a lithium ion battery. Background technique [0002] Lithium-ion batteries are considered to be the most promising chemical power source due to their high working voltage, high energy density, long cycle life, low self-discharge, no memory effect, wide operating temperature range, and no pollution to the environment, etc., and are widely used In all corners of society, including mobile phones, cameras, laptops, electric bicycles, etc., are closely related to people's lives and are inseparable. At the same time, due to energy shortages, lithium-ion batteries are expected to partially or completely replace gasoline and become energy storage devices for electric vehicles. [0003] Cathode materials...

Claims

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Application Information

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IPC IPC(8): H01M4/58H01M4/04C04B35/622C01B25/45C01B31/00
CPCY02E60/10
Inventor 王荣顺刘静谢海明王佳伟
Owner NORTHEAST NORMAL UNIVERSITY
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