Preparation method of lithium iron phosphate with high conductivity and high tap density

A lithium iron phosphate and tap density technology, applied in the field of electrochemical power supply material preparation, can solve the problems of insufficient material coating and uniform doping, limited improvement in electrical conductivity, reduced tap density, etc. The effect of uniform doping and simple preparation process

Inactive Publication Date: 2018-07-27
贵州唯特高新能源科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Among them, carbon coating has a limited improvement in the electrical conductivity of the material, and with the increase of carbon coating, the tap density of the material decreases, only 0.7-1.0g / cm 3 , although metal nanoparticle coating and ion doping effects can greatly improve the conductivity of the material, since the metal particle and ion doping process is a solid-solid mixture, it cannot fully coat and uniformly dope the material.

Method used

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  • Preparation method of lithium iron phosphate with high conductivity and high tap density

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Embodiment 1

[0020] A preparation method of lithium iron phosphate with high electrical conductivity and high tap density, comprising the following steps:

[0021] (1) First ferric chloride, sodium dihydrogen phosphate, manganese sulfate and sodium carboxymethyl cellulose solution are prepared as a mixed solution, wherein the concentration of ferric chloride solution is 1mol / L and sodium dihydrogen phosphate concentration is 1.2mol / L, sulfuric acid The manganese concentration is 0.1mol / L, and the amount of sodium carboxymethylcellulose added is 10% of the mass of ferric chloride;

[0022] (2) Synthesis of spherical metal ion doped iron phosphate precursor:

[0023] ① Slowly drop the mixed solution and 4% ammonia water at a flow rate of 200ml / h into a magnetic stirring container with pH=1.7 and 40ml of sodium dihydrogen phosphate solution as the bottom liquid, and at the same time control the pH value of the mixed solution by dropping ammonia water 1.3, stop the titration and continue to s...

Embodiment 2

[0029] A preparation method of lithium iron phosphate with high electrical conductivity and high tap density, comprising the following steps:

[0030] (1) Ferrous sulfate, phosphoric acid, aluminum sulfate and sodium carboxymethyl cellulose solution are prepared mixed solution earlier, wherein ferrous sulfate solution concentration is 1mol / L and phosphoric acid concentration 1.2mol / L, aluminum sulfate concentration 0.05mol / L , the amount of polyvinyl alcohol is 5% of the quality of ferrous sulfate;

[0031] (2) Synthesis of spherical metal ion doped iron phosphate precursor:

[0032] ① Slowly drop the mixed solution and 3% ammonia water at a flow rate of 100ml / h into a magnetic stirring container equipped with pH=1.3 and 30ml phosphoric acid solution as the bottom liquid, and at the same time control the pH value of the mixed solution to 1.4 by dropping ammonia water , the mixed solution drops or the volume of the mixed material reaches two-thirds of the reaction vessel, stop...

Embodiment 3

[0038] A preparation method of lithium iron phosphate with high electrical conductivity and high tap density, comprising the following steps:

[0039] (1) First ferric chloride, disodium hydrogen phosphate, zinc sulfate and sodium carboxymethyl cellulose solution are prepared as a mixed solution, wherein the concentration of ferric chloride solution is 1mol / L and the concentration of disodium hydrogen phosphate is 1.2mol / L, sulfuric acid The concentration of zinc is 0.07mol / L, and the amount of polythiophene added is 10% of the mass of ferric chloride;

[0040] (2) Synthesis of spherical metal ion doped iron phosphate precursor:

[0041] ① Slowly drop the mixed solution and 4% ammonia water at a flow rate of 150ml / h into a magnetic stirring container equipped with a pH=1.7, 35ml disodium hydrogen phosphate solution as the bottom liquid, and at the same time control the mixed solution by dropping ammonia water When the pH value is 1.2, stop the titration and continue to stir f...

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Abstract

The invention discloses a preparation method of lithium iron phosphate with high conductivity and high tap density. The method comprises the following steps: a Fe3+ source, a phosphorus source, a doping agent and a crystal form control agent are prepared into a mixed solution; the materials are slowly pumped into a magnetic stirring container equipped with a phosphoric acid solution in proportion,and the pH value is adjusted to 1.0-2.0 by ammoniacal liquor; at the same time, precipitate is heated and stirred in order to obtain a metal ion doped iron phosphate precursor; the iron phosphate precursor is filtered, washed and dried, and the precursor and a lithium source are uniformly mixed according to a mol ratio 1:1.02; under the protection of nitrogen-hydrogen gas mixture atmosphere, hightemperature treatment at 600-750 DEG C is carried out for 8-15 hours, in order to obtain metal ion doped lithium iron phosphate. The product has high conductivity and high tap density, and the methodhas the advantages of simple process, wide raw material sources, low cost, and concise preparation process; the method lays a foundation for industrialization.

Description

technical field [0001] The invention belongs to the technical field of preparation of electrochemical power source materials, and in particular relates to a method for preparing lithium iron phosphate with high electrical conductivity and high tap density. Background technique [0002] Among the developed lithium-ion cathode materials, lithium iron phosphate has become the most popular choice due to its environmental friendliness, low raw material cost, high theoretical capacity (170mAh / g), stable voltage platform, excellent safety performance, good thermal stability, and excellent cycle performance. A new generation of positive electrode material research hotspot. However, lithium iron phosphate has two obvious defects, one is poor conductivity, and the efficiency of high-rate charge and discharge is low; the other is low tap density, resulting in low volume specific capacity. These two defects affect the practical application of its materials. Especially the poor consiste...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58H01M10/0525C01B25/26C01B25/45C01B25/37
CPCC01B25/26C01B25/375C01B25/45H01M4/5815H01M10/0525Y02E60/10
Inventor 宫东杰李健刘俊才陈炬张仁国岳有涛王永松
Owner 贵州唯特高新能源科技有限公司
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