Preparation method of lithium-containing single-phase high-entropy negative electrode material and application of lithium-containing single-phase high-entropy negative electrode material in lithium battery negative electrode material

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a preparation method of a lithium-containing single-phase high-entropy negative electrode material and application of the lithium-containing single-phase high-entropy negative electrode material in a lithium battery negative electrode material.The preparation method comprises the following steps that S1, a container A and a container B are taken respectively, deionized water and absolute ethyl alcohol are added into the container A and the container B respectively, and then glacial acetic acid is added; s2, sequentially adding tetraethyl silicate, indium nitrate, germanium chloride, aluminum nitrate, lithium nitrate and citric acid into the container A, and adding tetrabutyl titanate into the container B; s3, mixing the solutions in the container A and the container B, heating and stirring to form gel; s4, drying the gel; and S5, drying and annealing the gel to obtain powder. According to the method, the pure-phase high-entropy oxide is synthesized, the mixed entropy of the high-entropy material is improved while pre-lithiation is performed, the high-entropy effect of the material is enhanced, and therefore the structural stability and thermodynamic stability of the material can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to a method for preparing a lithium-containing single-phase high-entropy negative electrode material and an application thereof in negative electrode materials for lithium batteries. Background Art

[0002] The common pre-lithiation technologies currently on the market mainly include:

[0003] 1. The lithium source (lithium metal or lithium compound) is reacted with the negative electrode material through a reduction reaction and directly introduced into the negative electrode active material. Although this method is simple, the degree of pre-lithiation is difficult to accurately control and the consistency between batches is poor. Similarly, the lithium supplementation effect can be achieved by directly adding reduced lithium powder, but lithium powder will reduce conventional electrolytes, binders, dispersants and other necessary auxiliary components in the lithium battery production process, so it is necessary to further surface modify it. At the same time, due to the high chemical activity of lithium metal in large-scale production, there are safety hazards.

[0004] 2. Electrochemical pre-lithiation refers to a method in which a lithium foil-electrolyte-negative electrode system is formed, and an external voltage is applied to allow lithium ions to actively diffuse through the electrolyte to the negative electrode and complete the pre-lithiation process. The degree of pre-lithiation is controlled by changing the applied voltage and duration. This method is highly safe and stable, but requires specific electrochemical equipment, adds additional steps and production difficulties, and requires a lower current to promote uniform lithium doping.

[0005] 3. Chemical pre-lithiation uses a very strong reducing lithium-containing reactant additive to treat the negative electrode, and transports the active lithium to the negative electrode material during the redox reaction. The vast majority of chemical pre-lithiation reactants are lithium-containing organic matter, such as biphenyl lithium, naphthyl lithium, butyl lithium, etc. Controlling the treatment time can play a role in regulating the degree of pre-lithiation (the treatment time is positively correlated with the degree of pre-lithiation). Of course, the activity of chemical lithium supplements is also very high (for example, butyl lithium is prone to exothermic reaction when it comes into contact with water and oxygen, high concentration (greater than 1.0M) solutions are prone to rapid combustion when they come into contact with humid air, and the solvents in the packaging containers are generally low-boiling flammable and explosive liquids, which are prone to explosion once heated and expanded). Its production, storage, transportation, application, and the selection of electrode binders are also relatively complex issues. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a lithium-containing single-phase high-entropy negative electrode material and its application in lithium battery negative electrode materials, so as to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for preparing a lithium-containing single-phase high-entropy negative electrode material comprises the following steps:

[0009] S1, take container A and container B respectively, add deionized water and anhydrous ethanol into container A and container B respectively, and then add glacial acetic acid into container A and container B;

[0010] S2, tetraethyl silicate, indium nitrate, germanium chloride, aluminum nitrate, lithium nitrate and citric acid are added to the mixed solution of deionized water and glacial acetic acid in container A in sequence, and tetrabutyl titanate is added to the mixed solution of anhydrous ethanol and glacial acetic acid in container B;

[0011] S3, the mixed solutions in container A and container B are vigorously stirred at room temperature for 1 hour, and after the stirring is completed, the mixed solution in container B is slowly added to the mixed solution in container A, and container A is placed on a constant temperature stirrer and stirred at 90° C. until a gel is formed;

[0012] S4, transferring the gel in the container A in step S3 to a forced air drying oven, and drying the gel at normal pressure;

[0013] S5. Scrape off the gel dried in step S4, and place it in a tube furnace for annealing to obtain a powder, which is a lithium-containing single-phase high-entropy negative electrode material.

[0014] Preferably, in step S1, the volume ratio between deionized water and glacial acetic acid in container A is 100:1, and the volume ratio between anhydrous ethanol and glacial acetic acid in container B is 100:1.

[0015] Preferably, in step S2, the molar ratio of tetraethyl silicate, indium nitrate, germanium chloride, aluminum nitrate, lithium nitrate, citric acid and tetrabutyl titanate is 4:4:4:1:1:1.5:1.

[0016] Preferably, in step S4, the drying temperature in the air drying oven is 185° C., and the drying time of the gel in the air drying oven is 24 hours.

[0017] Preferably, in step S5, the annealing temperature in the tube furnace is 500° C., and the annealing time is 8 hours.

[0018] Application of the lithium-containing single-phase high-entropy negative electrode material prepared by the above-mentioned lithium-containing single-phase high-entropy negative electrode material preparation method in lithium battery negative electrode materials.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention uses a sol-gel method and other preparation methods to synthesize a pure phase high entropy oxide by using a lithium source as one of the components of a high entropy material. During pre-lithiation, the mixing entropy of the high entropy material is increased, and the high entropy effect of the material is enhanced, thereby improving the structural stability and thermodynamic stability of the material. Compared with the pre-lithiation of the traditional doping concept, the present invention is simple to operate and does not require additional equipment. The lithium source is directly added to the crystal structure to ensure that no unnecessary impurities are generated. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The XRD patterns of the powders after annealing prepared in Example 1 and Comparative Example 1 of the present invention;

[0022] Figure 2 The figure is a charge and discharge test result diagram of the annealed powder prepared in Example 1 and Comparative Example 1 of the present invention when it is prepared into a pole piece (charge and discharge current density 100mA / g);

[0023] Figure 3 The graph is a test result of the cycle performance of the annealed powders prepared in Example 1 and Comparative Example 1 of the present invention when they are prepared into pole pieces (current density 1 A / g);

[0024] Figure 4 This is a test result diagram of the rate performance of the annealed powder prepared in Example 1 and Comparative Example 1 of the present invention when it is prepared into a pole piece. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] See also Figures 1 to 4 , the present invention provides:

[0027] Example 1

[0028] A method for preparing a lithium-containing single-phase high-entropy negative electrode material comprises the following steps:

[0029] S1. Take beaker A and beaker B respectively, add 200 ml of deionized water and 200 ml of anhydrous ethanol to beaker A and beaker B respectively, and then add 2 ml of glacial acetic acid to beaker A and beaker B respectively;

[0030] S2, to the mixed solution of deionized water and glacial acetic acid in beaker A, 0.4 mmol of tetraethyl silicate, 0.4 mmol of indium nitrate, 0.4 mmol of germanium chloride, 0.1 mmol of aluminum nitrate, 0.1 mmol of lithium nitrate and 1.5 mmol of citric acid were added in sequence, and 0.1 mmol of tetrabutyl titanate was added to the mixed solution of anhydrous ethanol and glacial acetic acid in beaker B;

[0031] S3, the mixed solutions in beaker A and beaker B were vigorously stirred at room temperature for 1 hour, and after the stirring was completed, the mixed solution in beaker B was slowly added to the mixed solution in beaker A, and beaker A was placed on a constant temperature stirrer and stirred at 90° C. until a gel was formed;

[0032] S4, transferring the gel in beaker A in step S3 to a forced air drying oven, and drying the gel at normal pressure at a drying temperature of 185° C. for 24 h;

[0033] S5. Scrape off the gel dried in step S4 and place it in a tubular furnace for annealing to obtain a powder, which is a lithium-containing single-phase high-entropy negative electrode material. The annealing temperature is 500° C. and the annealing time is 8 hours.

[0034] Comparative Example 1

[0035] The difference of Comparative Example 1 is that the addition of lithium nitrate is eliminated in step S2, and the remaining steps are exactly the same as those of Example 1.

[0036] The annealed powders of Example 1 and Comparative Example 1 were obtained respectively, and their qualitative characteristics (XRD diagram) were as follows: Figure 1 As shown;

[0037] The annealed powder in Example 1 and acetylene black and polyacrylic acid were mixed in a ratio of 7:1.5:1.5 to prepare a slurry, and the annealed powder in Comparative Example 1 and acetylene black and polyacrylic acid were mixed in a ratio of 7:1.5:1.5 to prepare a slurry. The two slurries were respectively coated on copper foil with a scraper, and then placed in a vacuum drying oven at 120°C for 12 hours, and a number of 12mm-sized electrodes were cut with a punching machine;

[0038] The electrode was placed in a glove box (water oxygen content < 0.1 ppm), and an electrolyte solution of EC:DEC = 1:1 and 10% FEC and 2% VC was added to form a button half-cell for subsequent electrochemical performance testing;

[0039] The assembled battery was left to stand for 12 hours and then charged and discharged at a current density of 100 mA / g. The results of the charge and discharge tests are as follows: Figure 2 As shown; the cycle performance test was carried out at a current density of 1A / g, and the cycle performance test results are as follows Figure 3As shown; the rate performance was tested at current densities of 0.1, 0.2, 0.5, 1, 2, and 5 A / g respectively. The test results of the rate performance are as follows Figure 4 shown.

[0040] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a lithium-containing single-phase high-entropy negative electrode material, characterized in that: The steps include: S1, take container A and container B respectively, add deionized water and anhydrous ethanol into container A and container B respectively, and then add glacial acetic acid into container A and container B; S2, tetraethyl silicate, indium nitrate, germanium chloride, aluminum nitrate, lithium nitrate and citric acid are added to the mixed solution of deionized water and glacial acetic acid in container A in sequence, and tetrabutyl titanate is added to the mixed solution of anhydrous ethanol and glacial acetic acid in container B; S3, the mixed solutions in container A and container B are vigorously stirred at room temperature for 1 hour, and after the stirring is completed, the mixed solution in container B is slowly added to the mixed solution in container A, and container A is placed on a constant temperature stirrer and stirred at 90° C. until a gel is formed; S4, transferring the gel in the container A in step S3 to a forced air drying oven, and drying the gel at normal pressure; S5. Scrape off the gel dried in step S4, and place it in a tube furnace for annealing to obtain a powder, which is a lithium-containing single-phase high-entropy negative electrode material.

2. The method for preparing a lithium-containing single-phase high-entropy negative electrode material according to claim 1, characterized in that: In step S1, the volume ratio of deionized water to glacial acetic acid in container A is 100:1, and the volume ratio of anhydrous ethanol to glacial acetic acid in container B is 100:

1.

3. The method for preparing a lithium-containing single-phase high-entropy negative electrode material according to claim 1, characterized in that: In step S2, the molar ratio of tetraethyl silicate, indium nitrate, germanium chloride, aluminum nitrate, lithium nitrate, citric acid and tetrabutyl titanate is 4:4:4:1:1:1.5:

1.

4. The method for preparing a lithium-containing single-phase high-entropy negative electrode material according to claim 1, characterized in that: In step S4, the drying temperature in the air drying oven is 185° C., and the drying time of the gel in the air drying oven is 24 hours.

5. The method for preparing a lithium-containing single-phase high-entropy negative electrode material according to claim 1, characterized in that: In step S5, the annealing temperature in the tube furnace is 500° C. and the annealing time is 8 hours.

6. Application of the lithium-containing single-phase high-entropy negative electrode material prepared by the method for preparing a lithium-containing single-phase high-entropy negative electrode material as described in any one of claims 1 to 5 in negative electrode materials for lithium batteries.

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