CN111268662A

CN111268662A - Preparation method of nanoscale iron phosphate particles

Info

Publication number: CN111268662A
Application number: CN202010060738.2A
Authority: CN
Inventors: 丁建民
Original assignee: Jiangsu Leneng Battery Inc Co
Current assignee: Jiangsu Leneng Battery Inc Co
Priority date: 2020-01-19
Filing date: 2020-01-19
Publication date: 2020-06-12

Abstract

The invention relates to a preparation method of nanoscale iron phosphate particles, belonging to the field of preparation of lithium ion battery anode materials, which is characterized in that a phosphorus source solution containing a certain amount of oxidant is sprayed into an iron source solution reactor containing ferrous ions at a certain feeding rate, the excess of an iron source is kept, the content of the oxidant, the system concentration, the stirring speed, the reaction time and the system temperature are controlled, a mixed solution containing nanoscale iron phosphate is generated, and nanoscale iron phosphate powder (FePO4.2H) is obtained after filtration, washing and drying₂O). The method has the advantages of low cost, simplicity, convenience, easy operation and high efficiency, and the prepared iron phosphate is nano-particles, uniform in particle size and narrow in distribution range, and is suitable for industrial production. The nano ferric phosphate is a good precursor material for preparing a high-power type lithium ion battery anode material lithium iron phosphate.

Description

Preparation method of nanoscale iron phosphate particles

Technical Field

The invention relates to a preparation method of nano-scale iron phosphate, which is an excellent precursor material for preparing a high-power type lithium ion battery anode material, namely lithium iron phosphate.

Background

The iron phosphate (FePO 4) is beige or grey white powder, is mainly researched in the fields of agriculture, ceramic glass, steel, surface passivation and the like at first, and is discovered to have unique catalytic property, ion exchange capacity and electrochemical performance, can be used as a novel battery anode material, and is an excellent raw material for preparing lithium iron phosphate serving as the lithium ion battery anode material.

The nanoscale lithium iron phosphate has good multiplying power performance and high compaction, and can be used in the fields of ultralow temperature, start-stop, quick charge and the like, so that the synthesis of a nanoscale lithium iron phosphate precursor, namely iron phosphate is particularly important. The disadvantages of the modified process are that uniform mixing cannot be ensured and the obtained nanoparticles have non-uniform size and particle size distribution. Because the ferric phosphate and the lithium iron phosphate have similar olive tree structures, the nano-scale lithium iron phosphate is obtained by the ferric phosphate design, and the particle size distribution and the morphological characteristics of the lithium iron phosphate are controlled from the source. The method for synthesizing the nano iron phosphate by the coprecipitation method is easy to control, low in reaction cost, simple and convenient to operate and high in efficiency, and the nano iron phosphate particles are prepared by controlling the oxidation degree of the reaction, namely the growth degree of the iron phosphate particles.

Disclosure of Invention

The invention can nano-convert the ferric phosphate original particles to be 30nm or below, and can shorten the transmission distance of electrons and ions so as to meet the precursor requirement of the high-rate and high-compaction type lithium iron phosphate cathode material.

The technical scheme of the invention is realized by the following modes: a preparation method of nano-scale iron phosphate particles comprises the following steps: preparing a phosphorus source solution and a ferrous iron source solution containing hydrogen peroxide; wherein the phosphorus source solution containing hydrogen peroxide is a solution containing phosphate ions and a certain amount of hydrogen peroxide and is prepared by adding hydrogen peroxide into phosphoric acid or soluble phosphate; the solution containing ferrous ions is prepared from water-soluble ferrous salt; spraying a phosphorus source solution containing a certain amount of hydrogen peroxide into an iron source solution reactor containing ferrous ions at a certain feeding rate, controlling the content of hydrogen peroxide, the stirring speed, the reaction time and the system temperature to generate a mixed solution containing nano iron phosphate, and filtering, washing and drying to obtain nano iron phosphate powder (FePO4.2H)₂O); the amount of the hydrogen peroxide is obtained according to the stoichiometric ratio of the chemical reaction, the excessive iron source is kept, the oxidation reaction degree is controlled, and the control on the size and the shape of the iron phosphate particles is realized.

Preferably, the concentration of phosphate ions in the phosphorus source solution containing hydrogen peroxide is 0.5-2.0 mol/L; the hydrogen peroxide is industrial grade or analytically pure grade hydrogen peroxide; the soluble phosphate is one or more of ammonium phosphate, ammonium monohydrogen phosphate, ammonium dihydrogen phosphate, sodium monohydrogen phosphate, sodium dihydrogen phosphate, potassium monohydrogen phosphate or potassium dihydrogen phosphate; preferably, the concentration of the ferrous ions is 0.5-2.0 mol/L. The water-soluble ferrous salt is one or more of ferrous nitrate, ferrous chloride or ferrous sulfate; selecting reaction temperature to be controlled between 60 ℃ and 90 ℃; preferably the stirring speed is between 100rpm and 1000 rpm; the reaction time is preferably between 30min and 5 h.

According to the invention, the growth and nucleation time of ferric phosphate in the reaction process are controlled through the preferable conditions, and the generated nano ferric phosphate FePO4.2H is prepared₂O is white amorphous powder with the particle size of 10-30 nm.

Drawings

FIG. 1 is an XRD diffraction profile of iron phosphate prepared in example 1 of the present invention;

fig. 2 is a scanning electron micrograph of the iron phosphate prepared in example 1 of the present invention.

Detailed Description

Example 1:

a preparation method of nanoscale iron phosphate particles comprises the steps of slowly dropwise adding 0.5mol/L phosphoric acid solution containing 10g of hydrogen peroxide into a three-neck flask filled with 0.5mol/L ferrous ion solution through a dropping funnel, heating the flask in a water bath at 60 ℃ to maintain the reaction temperature, adjusting the mechanical stirring speed to 100rpm, reacting for 30min, obtaining mixed liquid containing nanoscale iron phosphate after the color of a system turns white, filtering, washing and drying to obtain nanoscale iron phosphate powder (FePO4.2H)₂O), the XRD and SEM of the obtained iron phosphate are shown in figure 1 and figure 2.

Example 2:

slowly dripping 1.0mol/L phosphoric acid solution containing 15g of hydrogen peroxide into a three-neck flask filled with 1.0mol/L ferrous ion solution through a dropping funnel, heating the flask in a 70 ℃ water bath to maintain the reaction temperature, adjusting the mechanical stirring speed to 400rpm, reacting for 45min, obtaining mixed liquid containing nano iron phosphate after the color of a system turns white, filtering, washing and drying to obtain nano iron phosphate powder (FePO4.2H)₂O)。

Example 3:

preparation method of nano-scale iron phosphate particlesSlowly dripping 1.5mol/L phosphoric acid solution of 20g of hydrogen peroxide into a three-neck flask filled with 1.5mol/L ferrous ion solution through a dropping funnel, heating the flask in a water bath at 80 ℃ to maintain the reaction temperature, adjusting the mechanical stirring speed to 600rpm, reacting for 60min, obtaining mixed liquid containing nano iron phosphate after the system becomes white, filtering, washing and drying to obtain nano iron phosphate powder (FePO4.2H)₂O)。

Example 4:

slowly dripping 2.0mol/L phosphoric acid solution containing 25g of hydrogen peroxide into a three-neck flask filled with 2.0mol/L ferrous ion solution through a dropping funnel, heating the flask in a water bath at 90 ℃ to maintain the reaction temperature, adjusting the mechanical stirring speed to 1000rpm, reacting for 120min, generating mixed liquid containing nano iron phosphate after the color of a system turns white, filtering, washing and drying to obtain nano iron phosphate powder (FePO4.2H)₂O)。

Claims

1. A preparation method of nano-scale iron phosphate particles comprises the following steps:

preparing a phosphorus source solution and a ferrous iron source solution containing hydrogen peroxide; the phosphorus source solution containing hydrogen peroxide is a phosphate radical ion-containing solution and is prepared by adding hydrogen peroxide into phosphoric acid or soluble phosphate; the solution containing ferrous ions is prepared from water-soluble ferrous salt;

2) preparing nano-scale iron phosphate powder: spraying a phosphorus source solution containing a certain amount of hydrogen peroxide into an iron source solution reactor containing ferrous ions at a certain feeding rate for reaction, and controlling the content of hydrogen peroxide, the stirring speed, the reaction time and the system temperature to generate a mixed solution containing nano iron phosphate; filtering, washing and drying to obtain the nano-scale white amorphous ferric phosphate powder (FePO4.2H)₂O); the particle size is between 10 and 30 nm.

2. The method for preparing nanoscale iron phosphate particles according to claim 1, wherein: the concentration of phosphate ions in the phosphorus source solution containing hydrogen peroxide in the step 1) is 0.5-2.0 mol/L; the hydrogen peroxide is industrial grade or analytically pure grade hydrogen peroxide; the soluble phosphate is one or more of ammonium phosphate, ammonium monohydrogen phosphate, ammonium dihydrogen phosphate, sodium monohydrogen phosphate, sodium dihydrogen phosphate, potassium monohydrogen phosphate or potassium dihydrogen phosphate.

3. The method for preparing nanoscale iron phosphate particles according to claim 1, wherein: the concentration of ferrous ions in the step 1) is 0.5-2.0 mol/L; the water-soluble ferrous salt is one or more of ferrous nitrate, ferrous chloride or ferrous sulfate.

4. The method for preparing nanoscale iron phosphate particles according to claim 1, wherein: in the step 2), the reaction temperature is controlled to be between 60 and 90 ℃, and the reaction time is between 30min and 5 h.

5. The method for preparing nanoscale iron phosphate particles according to claim 1, wherein: the stirring speed in the step 3) is between 100rpm and 1000 rpm.