CN109817938B

CN109817938B - A kind of preparation method of iron-based negative electrode material

Info

Publication number: CN109817938B
Application number: CN201910113772.9A
Authority: CN
Inventors: 高波; 王艺璇; 李魁; 付海洋; 朱广林; 胡成龙
Original assignee: Northeastern University China
Current assignee: Northeastern University China
Priority date: 2019-02-14
Filing date: 2019-02-14
Publication date: 2021-11-05
Anticipated expiration: 2039-02-14
Also published as: CN109817938A

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a preparation method of an iron-based negative electrode material. The surface of the nano iron oxide is chemically plated with nickel, and the iron oxide particles are subjected to nanocrystallization, so that the contact area of the iron oxide can be increased, and the electrochemical performance is enhanced. Chemical plating is a surface technology which is simple and convenient to operate, can be deposited on the surface of an iron oxide material, is uniform in plating layer, and has good coating property, corrosion resistance and wear resistance. The surface of the iron-based negative electrode material is plated with a layer of substance with better conductivity by chemical plating, so that the conductivity of the material can be improved, the problem of volume expansion in the circulating process is solved, and the plating missing phenomenon is avoided by repeating the chemical plating process for 2-3 times, so that the electrochemical performance of the negative electrode material is further improved, and the high-performance iron-based negative electrode material is prepared.

Description

Preparation method of iron-based negative electrode material

Technical Field

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a preparation method of an iron-based negative electrode material.

Background

The lithium ion battery has the advantages of large energy density, high working voltage, small self-discharge, no memory effect, wide temperature range and the like, and becomes the secondary battery with the most excellent comprehensive performance at present. Compared with the traditional graphite negative electrode material (with the theoretical specific capacity of 372mAh/g), Fe₂O₃(the theoretical specific capacity is 1005mAh/g) has attracted high attention as the negative electrode material of the lithium ion battery. However, Fe is involved in the process of lithium ion intercalation and deintercalation₂O₃Pulverization and serious particle agglomeration occur, thereby causing the reduction of electron transmission and diffusion performance, too fast capacity attenuation, short cycle period,seriously affecting its further application as anode material in lithium ion batteries.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a preparation method of an iron-based negative electrode material, which improves the conductivity of the material through surface chemical plating of the iron-based negative electrode material and inhibits the problem of volume expansion in the circulating process so as to prepare the high-performance iron-based negative electrode material.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of an iron-based negative electrode material comprises the following steps:

(1) taking an iron-based material, wherein the iron-based material is nano iron oxide powder; coarsening and sensitizing activation are carried out;

(2) preparing a plating solution: mixing the main salt solution and the complexing agent solution, sequentially adding the stabilizer and the surfactant, and uniformly mixing to obtain a plating solution; the main salt is nickel salt; the concentration of the main salt solution in the plating solution is 10-40g/L, the concentration of the complexing agent is 0.03-006mol/L, and the concentration of the stabilizing agent is (1-3) multiplied by 10^-6mol/L, the concentration of the surfactant is (0.5-1.5) x 10^- ⁶mol/L；

(3) Adding the activated iron-based material into a plating solution, adjusting the pH value of the plating solution to 12-13, slowly adding a reducing agent, and performing chemical plating, wherein the chemical plating temperature is 65-70 ℃, and the plating time is 70-120 min;

(4) and cleaning the iron-based material subjected to chemical plating with deionized water, and drying to obtain the iron-based lithium ion battery cathode material.

In the step (1), the preparation process of the nano iron oxide powder comprises the following steps: dissolving a certain amount of ferric chloride hexahydrate in deionized water, dropwise adding a sodium hydroxide solution, and adjusting the pH value of the system to be more than 10. Transferring the obtained product into a high-pressure reaction kettle, and carrying out hydrothermal reaction at 200 ℃ for 10 hours. And cooling, carrying out vacuum filtration, filtering to obtain a red product, washing the product with deionized water, and drying in a constant-temperature drying oven at 60 ℃ for 12 h. And taking out a sample obtained by drying, putting the sample into a clean crucible, and calcining the sample in a muffle furnace at 300 ℃ for 2 hours.

In the step (1), the coarsening process of the iron-based material comprises the following steps: performing coarsening and acidification treatment for 5min by using nitric acid solution with volume fraction of 10% while ultrasonically stirring, and washing to be neutral by using distilled water.

In the step (1), a sensitization activation fractional step method is adopted for sensitization activation of the iron-based material, and a sensitization liquid is prepared from 10g of a sensitizer, 40ml of concentrated hydrochloric acid and 1000ml of distilled water. Weighing a certain amount of deoiled powder into a quantitative sensitizing solution, sensitizing for 3-5 min under the ultrasonic stirring of 150W, taking out, and washing with distilled water until no chloride ion exists. The activating solution was prepared from 3.5g of silver nitrate +7g/L of aqueous solution of NaOH +100ml/L of aqueous ammonia. And (3) measuring a certain amount of activating liquid, adding the activating liquid into the sensitized powder, and activating for 10-15 min under the ultrasonic stirring of 150W.

In the step (2), the nickel salt is specifically one of nickel nitrate, nickel sulfate or nickel chloride.

In the step (2), the complexing agent is one of ethylenediamine, sodium citrate or disodium ethylenediamine tetraacetate, the stabilizer is one of thiourea, urea or ammonium sulfide, and the surfactant is one of sodium dodecyl sulfate, sodium dodecyl sulfate or sodium dodecyl benzene sulfonate.

In the step (3), the reducing agent is hydrazine hydrate, and the addition amount is 10-150ml/L of the plating solution.

In the step (4), the chemical plating times are 2-3 times so as to avoid the condition of plating leakage.

When the prepared iron-based negative electrode material is used as a lithium ion battery negative electrode, the current density is 100mA/g, the specific capacity is stabilized at 650-800mAh/g after 100 cycles, and the coulombic efficiency reaches 96-98%.

In the invention, the contact area of the iron oxide can be increased by nano-converting the iron oxide particles, and the electrochemical performance is enhanced. Chemical plating is a surface technology which is simple and convenient to operate, can be deposited on the surface of an iron oxide material, is uniform in plating layer, and has good coating property, corrosion resistance and wear resistance. Therefore, the surface of the iron-based negative electrode material is plated with a layer of substance with better conductivity by chemical plating, so that the conductivity of the material can be improved, the problem of volume expansion in the circulating process is solved, and the plating missing phenomenon is avoided by repeating the chemical plating process for 2-3 times, thereby further improving the electrochemical performance of the negative electrode material.

The invention has the beneficial effects that:

the invention adopts the surface chemical nickel plating of the nano iron oxide, even secondary chemical plating, thereby improving the conductivity of the material, buffering the problem of volume expansion of the iron-based negative electrode material in the circulating process and improving the electrochemical performance.

Detailed Description

The present invention will be described in further detail with reference to examples.

Example 1

(1) Dissolving a certain amount of ferric chloride hexahydrate in deionized water, dropwise adding a sodium hydroxide solution, and adjusting the pH value of the system to be more than 10. Transferring the obtained product into a high-pressure reaction kettle, and carrying out hydrothermal reaction at 200 ℃ for 10 hours. And cooling, carrying out vacuum filtration, filtering to obtain a red product, washing the product with deionized water, and drying in a constant-temperature drying oven at 60 ℃ for 12 h. And taking out a sample obtained by drying, putting the sample into a clean crucible, and calcining the sample in a muffle furnace at 300 ℃ for 2 hours. Obtaining nano iron oxide powder; (2) putting nano iron oxide powder into the coarsening solution of nitric acid, stirring at room temperature, cleaning to be neutral by deionized water, and then sensitizing and activating by adopting a sensitizing and activating step method; (3) mixing nickel sulfate solution and 0.05mol/L ethylenediamine solution, and sequentially adding 2 × 10^-6mol/L Thiourea and 1X 10^-6mol/L sodium dodecyl sulfate, wherein the concentration of the main salt is 20 g/L; (4) adding the product obtained in the step (2) into the plating solution prepared in the step (3), adjusting the pH value to 12, slowly adding a hydrazine hydrate solution, and performing chemical plating for 60min at 70 ℃, wherein the use amount of hydrazine hydrate is 50 ml/L; (5) washing with deionized water and drying; (6) and repeating the secondary chemical plating to obtain the iron-based negative electrode material. The negative electrode material is used as a lithium ion battery negative electrode, and after 100 cycles under the current density of 100mA/g, the specific capacity is stabilized at 655mAh/g, and the coulombic efficiency is 96.5%.

Example 2

(1) Dissolving a certain amount of ferric chloride hexahydrate in deionized water, dropwise adding a sodium hydroxide solution, and adjusting the pH value of the system to be more than 10. Transferring the obtained product into a high-pressure reaction kettle,carrying out hydrothermal reaction at 200 ℃ for 10 h. And cooling, carrying out vacuum filtration, filtering to obtain a red product, washing the product with deionized water, and drying in a constant-temperature drying oven at 60 ℃ for 12 h. And taking out a sample obtained by drying, putting the sample into a clean crucible, and calcining the sample in a muffle furnace at 300 ℃ for 2 hours. Obtaining nano iron oxide powder; (2) putting nano iron oxide powder into the coarsening solution of nitric acid, stirring at room temperature, cleaning to be neutral by deionized water, and then sensitizing and activating by adopting a sensitizing and activating step method; (3) mixing nickel sulfate solution and 0.05mol/L ethylenediamine solution, and sequentially adding 2 × 10^-6mol/L Thiourea and 1X 10^-6mol/L sodium dodecyl sulfate, wherein the concentration of the main salt is 30 g/L; (4) adding the product obtained in the step (2) into the plating solution prepared in the step (3), adjusting the pH value to 13, slowly adding a hydrazine hydrate solution, and performing chemical plating for 60min at 65 ℃, wherein the use amount of hydrazine hydrate is 50 ml/L; (5) washing with deionized water and drying; (6) and repeating the secondary chemical plating to obtain the iron-based negative electrode material. The negative electrode material is used as a lithium ion battery negative electrode, and after 100 cycles under the current density of 100mA/g, the specific capacity is stabilized at 780mAh/g, and the coulombic efficiency is 97.55%.

Claims

1. a preparation method of iron-based negative electrode material, is characterized in that, comprises the following steps:

(1) Take iron-based material, which is nano-iron oxide powder; carry out roughening, sensitization and activation; the roughening process of iron-based material is: use a nitric acid solution with a volume fraction of 10%, and roughen in ultrasonic stirring Acidify for 5 minutes, and wash with distilled water until neutral; the sensitization and activation of iron-based materials adopts the sensitization and activation step-by-step method, and the configuration of the sensitizer is 10g sensitizer + 40ml concentrated hydrochloric acid + 1000ml distilled water; weigh a certain amount of The degreasing powder is sensitized in a quantitative sensitizing solution under ultrasonic stirring at 150W for 3-5 minutes, taken out, and washed with distilled water until there is no chloride ion; the configuration of the activation solution is 3.5g silver nitrate + 7g/ LNaOH solution + 100ml/L ammonia water; measure a certain amount of activation solution, add it to the sensitized powder, and activate it for 10-15min under ultrasonic stirring at 150W;

(2) Preparation of the plating solution: after mixing the main salt solution and the complexing agent solution, the stabilizer and the surfactant are added in turn, and the mixture is uniform to obtain a plating solution; the main salt is a nickel salt; the main salt in the plating solution The solution concentration is 10-40g/L, the complexing agent concentration is 0.03-006mol/L, the stabilizer concentration is (1～3)×10 ^-6 mol/L, and the surfactant concentration is (0.5～1.5)×10 ^{- 6} mol/L; Described complexing agent is a kind of in ethylenediamine, sodium citrate or disodium EDTA, stabilizer is a kind of in thiourea, urea or ammonium sulfide, and surfactant is One of sodium dodecyl sulfate, sodium dodecyl sulfonate or sodium dodecyl benzene sulfonate;

(3) Add the activated iron-based material into the plating solution, adjust the pH value of the plating solution to 12-13, slowly add a reducing agent, the reducing agent is hydrazine hydrate, and the addition amount is 10-150ml/L of the plating solution; carry out chemical plating , wherein, the electroless plating temperature is 65-70 ℃, the plating time is 70-120min; the number of electroless plating is 2 to 3 times to avoid leakage plating;

(4) The iron-based material after electroless plating is washed with deionized water and then dried to obtain an iron-based lithium ion battery negative electrode material.

2. The preparation method of a kind of iron-based negative electrode material according to claim 1, characterized in that, in the step (2), the nickel salt is one of nickel nitrate, nickel sulfate or nickel chloride.

3. the preparation method of a kind of iron-based negative electrode material according to claim 1 and 2, is characterized in that, in described step (1), the preparation process of nano iron oxide powder is: take a certain amount of hexahydrate chlorination Iron was dissolved in deionized water, sodium hydroxide solution was added dropwise, and the pH value of the system was adjusted to be greater than 10; the obtained product was transferred to an autoclave, and hydrothermally reacted at 200 °C for 10 h; after cooling, vacuum filtration was performed to obtain a red product, After washing the product with deionized water, it was put into a constant temperature drying oven at 60°C for drying for 12h; the dried samples were taken out and placed in a clean crucible, and calcined in a muffle furnace at 300°C for 2h.

4. the application of the iron-based negative electrode material prepared by any one of claims 1 to 3, characterized in that, when the prepared iron-based negative electrode material is used as a lithium ion battery negative electrode, the current density is 100mA/g, and after 100 cycles , the specific capacity is stable at 650-800mAh/g, and the Coulomb efficiency reaches 96-98%.