Synthetic method for high-purity iron phosphate and doped metallic element thereof

A technology of high-purity iron phosphate and metal elements, which is applied in the direction of electrical components, active material electrodes, battery electrodes, etc., can solve the problems of hindering lithium extraction/intercalation, lithium content reduction, environmental pollution, etc., and reduce the cost of reaction equipment and control Requirements, reduce waste water discharge, reduce the effect of production cost

Active Publication Date: 2015-12-23
SHANDONG GOLDENCELL ELECTRONICS TECH
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  • Application Information

AI Technical Summary

Problems solved by technology

As electrode material LiFePO 4 There are two main problems in itself: low electronic conductivity and lithium ion diffusion rate
It is easy to introduce Fe(OH) into the synthesized iron phosphate 3 , Na elements and other impurities, while the waste liquid contains SO 4 2- or NO 3 - Plasma pollutes the environment. Compared with the target product, the active ingredient content in the raw material is low, the preparation process is harsh, and the synthesis cost is high.
[0004] to LiFePO 4 In the study of material iron doping, it is generally used to add a certain stoichiometric ratio of doped metal compounds to the raw material, and FePO is rarely used. 4 As a raw material, and the lithium site is easily replaced by metal ions when the iron site is doped, resulting in a decrease in the lithium content, which may also hinder the extraction / intercalation of lithium
The Chinese patent (CN101692488A) uses ferric salt as the iron source, phosphate as the phosphorus source, and other metal cations are added, and the pH value is controlled by ammonia water to synthesize iron phosphate doped with metal elements, but there is also environmental pollution. Low active ingredient content and easy introduction of Fe(OH) 3 , Na elements and other impurities

Method used

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  • Synthetic method for high-purity iron phosphate and doped metallic element thereof
  • Synthetic method for high-purity iron phosphate and doped metallic element thereof
  • Synthetic method for high-purity iron phosphate and doped metallic element thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] (1) With ferrous oxalate (purity 99%) as iron source, phosphoric acid (purity 85%) as phosphorus source, according to molar ratio: n(Fe):n(P)=1:1.01 ratio, weigh oxalate Iron 87.80g, phosphoric acid 69.86g, polyethylene glycol is 0.02wt% of iron source;

[0029] (2) Dissolve phosphoric acid in 2L of distilled water, transfer it into a 3L reaction kettle, add polyethylene glycol, stir at 60rpm for 5min, and heat to 60°C in a water bath;

[0030] (3) Slowly add ferrous oxalate, and adjust the stirring speed to 300rpm;

[0031] (4) react for 3h until the precipitate turns white;

[0032] (5) Aging for 1 hour after the completion of the reaction, washing with distilled water until the pH value = 6.5, filtering and drying the precipitate at 120°C for 4 hours to obtain white ferric phosphate hydrate (FePO 4 2H 2 O).

[0033] The particle size of the obtained water and iron phosphate is 2~5μm (such as figure 1 shown), with a purity of 99.5%; the synthesized FePO 4 2H 2 ...

Embodiment 2

[0035] (1) With ferric oxide (purity 99%) as iron source, phosphoric acid (purity 85%) as phosphorus source, according to molar ratio: n(Fe):n(P)=1:1.02 ratio, weigh three Ferric oxide 48.73g, phosphoric acid 70.55g, polyvinylpyrrolidone is 0.05wt% of iron source;

[0036] (2) Dissolve phosphoric acid in 2L of distilled water, transfer it into a 3L reaction kettle, add polyvinylpyrrolidone, stir at 60rpm for 5min, and heat to 80°C in a water bath;

[0037] (3) Slowly add ferrous oxalate, and adjust the stirring speed to 1000rpm;

[0038] (4) After 2 hours of reaction, when the solution is gray-green, add 20ml H 2 o 2 , the precipitate turned yellow-white, and continued to stir for 2 hours;

[0039] (5) Aging for 2 hours after the completion of the reaction, then washing with distilled water until the pH value = 6.5, filtering and drying the precipitate at 110°C for 5 hours to obtain yellow-white ferric phosphate hydrate (FePO 4 2H 2 (2), the purity is 99.5%;

[0040] Usi...

Embodiment 3

[0042] (1) Using ferrous oxalate (purity 99%) as iron source, phosphoric acid (purity 85%) as phosphorus source, prepared by doping manganese dioxide Molar ratio: n(Fe):n(P):n(Mn )=0.97:1.01:0.03 ratio, take ferrous oxalate 85.16g, phosphoric acid 70.55g, manganese dioxide 1.60g, polyvinylpyrrolidone is 0.03wt% of iron source;

[0043] (2) Fully mix manganese dioxide and ferrous oxalate with a ball mill at a speed of 200 rpm for 1 hour;

[0044] (3) Dissolve phosphoric acid in 2.5L of distilled water and move it into a 4L reaction kettle, add polyvinylpyrrolidone, stir at 60rpm for 5min, heat in a water bath to 60°C; slowly add ferrous oxalate and dioxide A mixture of manganese, and adjust the stirring speed to 1500rpm;

[0045] (4) After reacting for 2 hours, add 20ml H 2 o 2 , the precipitate turned yellow-white, and the stirring was continued for 6 hours;

[0046] (5) Aging for 6 hours after the completion of the reaction, then washing with distilled water to pH = 7.0, ...

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Abstract

The invention relates to a synthetic method for high-purity iron phosphate and a doped metallic element thereof. A material prepared by the synthetic method is mainly applied to the preparation of a high-quality electrode material, namely lithium iron phosphate, and the synthetic method comprises the following steps: taking a phosphor source, an iron source compound and a doped metallic oxide as raw materials, adding a surfactant, reacting by high-speed stirring under normal pressure and low temperature, finally synthesizing into the substance of which the chemical formula is Fe1-xMxPO4.nH2O through seasoning, washing, filtering and drying, wherein M is the doped metallic element, and x is greater than or equal to 0 and smaller than or equal to 3, and n is greater than or equal to 0 and smaller than or equal to 2. The pH value is not needed to control in the synthetic process, and the requirement on equipment is low, moreover, the preparation technology is simple and environment-friendly; a synthesized product is low in cost, stable in performance and high in purity.

Description

technical field [0001] The invention relates to a synthesis method of high-purity iron phosphate and its doping with trace metal elements. The prepared material is mainly used in the preparation of electrode material lithium iron phosphate. Background technique [0002] Since 1997, Professor Goodenough of the University of Texas published LiFePO 4 Since the research results of lithium-ion cathode materials, it has attracted the attention of many researchers at home and abroad. As electrode material LiFePO 4 There are two main problems in itself: low electronic conductivity and lithium ion diffusion rate. The current modification methods are mainly carbon coating and crystal phase doping, in which the iron site is doped with excessive metal Mn 2+ 、Ni 2+ 、Co 2+ and non-transition metal ion Mg 2+ , Ca 2+ 、Al 3+ 、Cr 3+ 、Ti 4+ , V 5+ Wait for more research. [0003] There are many ways to synthesize ferric orthophosphate, most of which are prepared by reacting ferric ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58H01M4/136H01M4/1397
CPCH01M4/136H01M4/1397H01M4/5825H01M2004/028Y02E60/10
Inventor 关成善宗继月李涛周会梅庆虎任士界
Owner SHANDONG GOLDENCELL ELECTRONICS TECH
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