CN112670476A - Preparation method of lithium ion storage battery anode material LiF/Fe compound - Google Patents

Abstract

The invention relates to the field of lithium ion storage batteries, in particular to a positive electrode material LiF/Fe compound and a preparation method thereof. 1) Adding NaOH solution and hydrazine hydrate solution into a three-neck flask, and stirring at the temperature of 60-100 ℃; 2) the three-mouth flask is respectively connected with a condenser pipe, a thermometer and a nitrogen pipe, and is heated and stirred; 3) adding a surfactant sodium dodecyl benzene sulfonate; 4) FeC1₂·4H₂0 in distilled water (NaOH and FeC 1)₂·4H₂0 mass ratio of 4-5: 1), adding the mixture into a three-neck flask, reacting for a period of time, and enabling the solution to become grey green and continuously have black iron powderAnd (4) generating. In the invention, the positive electrode material adopts sodium dodecyl benzene sulfonate as a surfactant, and an intermediate product Fe (OH) in the inhibition process₂The agglomeration of colloidal particles reduces the size of iron particles, can remarkably change the surface appearance of the compound and improves the first discharge capacity and the capacity retention rate.

Description

Preparation method of lithium ion storage battery anode material LiF/Fe compound

Technical Field

The invention relates to the field of lithium ion storage batteries, in particular to a preparation method of a lithium ion storage battery anode material LiF/Fe compound.

Background

In the research of electrode materials of lithium ion batteries, a positive electrode material with a higher potential relative to Li and a negative electrode material with a lower potential relative to Li are always expected, and the electrode materials have larger lithium storage capacity, generally speaking, increasing the ionic bond strength of the materials will help to improve the working voltage of a battery adopting the materials as an electrode, fluorine has the strongest electronegativity in the periodic table of elements, the ionic bond strength of the formed transition metal fluoride is very high, and the discharge potential plateau is correspondingly higher when the material is used as an electrode material.

The currently reported transition metal fluoride cathode material mainly comprises FeF₃、NiF₂、CuF₂And the like. Most transition metal fluorides have good ionic conductivity, but their electronic conductivity is generally poor due to a large band gap created by the strong ionic bonding characteristics of transition metal fluorides, which is also a major factor in the limitation of transition metal fluorides as positive electrode materials for lithium ion batteries.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a preparation method of a lithium ion storage battery anode material LiF/Fe compound.

The technical scheme for realizing the purpose of the invention is as follows:

a lithium ion battery anode material LiF/Fe compound, the ratio of the mass: fe: LiF 1: 3.

A preparation method of a ternary lithium ion storage battery anode material comprises the following specific steps:

s1, adding a NaOH solution and a hydrazine hydrate solution into a three-neck flask, and adding a magnetic stirring rod into the three-neck flask for stirring at the temperature of 60-100 ℃;

s2, respectively connecting the three-mouth flask with a condenser, a thermometer and a nitrogen inlet pipe, fixing the three-mouth flask, heating by using a temperature control heating jacket and simultaneously stirring;

s3, adding sodium dodecyl benzene sulfonate serving as a surfactant into a three-neck flask, wherein the concentration of the sodium dodecyl benzene sulfonate is 0.2-0.8 mol/L;

s4, FeC1₂·4H₂0 in distilled water (NaOH and FeC 1)₂·4H₂0 mass ratio of 4-5: 1), adding the mixture into a three-neck flask, reacting for a period of time, and then enabling the solution to become grey green and continuously generating black iron powder;

s5, after the reaction is finished, pouring out the supernatant after the solution is cooled, adding deionized water, standing, pouring out the supernatant again, and repeating the steps until the pH value of the system is reduced to 7;

s6, reacting LiOH. H₂Dissolving O in deionized water, mixing with the prepared iron powder system, and adding an HF solution dropwise under magnetic stirring (ensuring the quantity ratio of Fe: LiF to 1: 3);

s7, after full reaction, carrying out suction filtration, washing with deionized water and absolute ethyl alcohol for multiple times, and then carrying out vacuum drying in a vacuum drying oven at 30-50 ℃ for 9-15 h;

and S8, after drying, taking out the sample, grinding, sieving, sealing and storing.

After the technical scheme is adopted, the invention has the following positive effects:

(1) the invention adopts LiF/Fe compound, which improves the electron conductivity of transition metal fluoride.

(2) The invention adopts sodium dodecyl benzene sulfonate as a surfactant, and inhibits an intermediate product Fe (OH) in the process₂The agglomeration of colloidal particles reduces the size of the iron particles.

(3) According to the invention, sodium dodecyl benzene sulfonate is adopted as a surfactant, so that the surface appearance of the LiF/Fe compound can be obviously changed, and the first discharge capacity and the capacity retention rate are improved.

Drawings

In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the present disclosure taken in conjunction with the accompanying drawings, in which

FIG. 1a) is an SEM image of a LiF/Fe composite prior to addition of a surfactant;

FIG. 1b) is an SEM image of the LiF/Fe composite after the addition of the surfactant, the reaction temperature is 100 ℃, and the concentration of the surfactant is 0.06 mol/L;

FIG. 2 is a graph of the cycling performance of LiF/Fe composite electrodes before and after addition of surfactant.

Detailed Description

(example 1)

In this embodiment, the positive electrode material LiF/Fe composite of the lithium ion battery has the following ratio of the amount of substances: fe: LiF 1: 3.

(1) Adding 20g of NaOH solution and 20mL of 80% hydrazine hydrate solution in percentage by mass into a three-neck flask, and adding a magnetic stirring rod into the three-neck flask for stirring;

(2) the three-neck flask is respectively connected with a condenser pipe, a thermometer and a nitrogen inlet pipe, the three-neck flask is fixed, heated by a temperature control heating jacket and stirred at the same time, and the temperature is 100 ℃;

(3) sodium dodecyl benzene sulfonate is used as a surfactant, the concentration is 0.06mol/L, and the sodium dodecyl benzene sulfonate is added into a three-neck flask;

(4) 4g of FeC1₂·4H₂0 in distilled water (NaOH and FeC 1)₂·4H₂0 mass ratio of 5:1), adding the mixture into a three-neck flask, reacting for a period of time, and then enabling the solution to become grey green and continuously generating black iron powder;

(5) after the reaction is finished, pouring out the supernatant liquor after the solution is cooled, adding deionized water, standing, pouring out the supernatant liquor again, and repeating the steps until the pH value of the system is reduced to 7;

(6) reacting LiOH & H₂Dissolving O in deionized water, mixing with the prepared iron powder system, and adding an HF solution dropwise under magnetic stirring (ensuring the quantity ratio of Fe: LiF to 1: 3);

(7) after full reaction, performing suction filtration, washing with deionized water and absolute ethyl alcohol for multiple times, and then performing vacuum drying in a vacuum drying oven at 40 ℃ for 12 hours;

(8) and after drying, taking out the sample, grinding, sieving, sealing and storing.

(example 2)

This example is substantially the same as example 1, and is distinguished by: the surfactant sodium dodecyl benzene sulfonate was not added.

Fig. 1 is an SEM image of LiF/Fe composite before and after adding a surfactant, and it can be seen from the figure that the size of iron particles in LiF/Fe composite without adding a surfactant is about 5 μm, and it can be seen that a cubic structure is apparent, contact of LiF and Fe is not sufficient, but distributed sporadically on the surface of iron particles, and also partial lithium fluoride forms its own crystals (spherical structure in the figure); the size of iron particles in the LiF/Fe compound prepared by adding the surfactant (the concentration is 0.06mol/L) is reduced to be within 1 micron, and an obvious sheet structure can be seen, the contact between LiF and Fe is very sufficient, and LiF particles form a relatively regular sphere. This shows that the addition of surfactant during the preparation process can significantly reduce the size of the iron particles and can significantly change the surface morphology of the composite.

Fig. 2 is a cycle performance curve of the LiF/Fe composite electrode before and after the addition of the surfactant, and it can be seen from the graph that after the addition of the surfactant, the first discharge specific capacity of the composite electrode is obviously improved, and the capacity retention rate is also improved to a certain extent.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (3)

1. A lithium ion battery anode material LiF/Fe compound is characterized in that: the anode material is LiF/Fe compound, and the ratio of the amount of substances: fe: LiF 1: 3.

2. The preparation method of the LiF/Fe composite of the lithium ion battery anode material according to claim 1, characterized by comprising the following steps:

s1, adding a NaOH solution and a hydrazine hydrate solution into a three-neck flask, and adding a magnetic stirring rod into the three-neck flask for stirring;

s2, respectively connecting the three-neck flask with a condenser pipe, a thermometer and a nitrogen introducing pipe, fixing the three-neck flask, heating by using a temperature control heating jacket and simultaneously stirring at the temperature of 60-100 ℃;

s3, adding a surfactant into the three-neck flask;

s4, FeC1₂·4H₂0 in distilled water (NaOH and FeC 1)₂·4H₂0 mass ratio of 4-5: 1), adding the mixture into a three-neck flask, reacting for a period of time, and then enabling the solution to become grey green and continuously generating black iron powder;

s5, after the reaction is finished, pouring out the supernatant after the solution is cooled, adding deionized water, standing, pouring out the supernatant again, and repeating the steps until the pH value of the system is reduced to 7;

s6, reacting LiOH. H₂Dissolving O in deionized water, mixing with the prepared iron powder system, and adding an HF solution dropwise under magnetic stirring (ensuring the quantity ratio of Fe: LiF to 1: 3);

s7, after full reaction, carrying out suction filtration, washing with deionized water and absolute ethyl alcohol for multiple times, and then carrying out vacuum drying in a vacuum drying oven at 30-50 ℃ for 9-15 h;

and S8, after drying, taking out the sample, grinding, sieving, sealing and storing.

3. The method of preparing a lithium ion battery positive electrode material LiF/Fe composite according to claim 2, wherein: the surfactant in S3 is sodium dodecyl benzene sulfonate, and the concentration is 0.2 mol/L-0.8 mol/L.

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