A method for preparing negative electrode material for lithium ion battery

Abstract

The invention discloses a method for preparing a negative electrode material for a lithium ion battery, which belongs to the technical field of lithium ion batteries and comprises the following steps: mixing LiF with hydrochloric acid and heating the mixture, and then adding Ti into the solution. 3 AlC 2 After the material is mixed, it is magnetically stirred to obtain a mixed solution. The mixed solution is centrifuged and washed, and LiCl solution is added. After standing, it is centrifuged again. After the centrifugation is completed, the lower layer of precipitation is taken out, and the sample is freeze-dried to obtain a sample MXene powder. The prepared sample MXene powder is stirred with water, and then BiCl is added. 3 The test solution was stirred continuously, and after being mixed evenly, it was filtered to form a film, and after drying, a MXene composite film was obtained. The MXene composite film was placed in NaBH 4 The solution is reacted, and after the reaction, the MXene / Bi composite material is obtained by drying. 3 and NaBH 4 The reaction displaces Bi nanoparticles distributed on the surface of MXene nanosheets, forming a relatively stable three-dimensional structure, which provides more attachment sites for Li storage. The presence of Bi improves the lithium storage performance of MXene.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a method for preparing a negative electrode material for a lithium ion battery. Background Art

[0002] Lithium-ion batteries are the dominant energy storage devices in the market. They have high energy density, wide operating voltage window, no memory effect and other characteristics, which greatly promote the development of industries such as smart phones, laptops, and electric vehicles. The negative electrode material of traditional lithium-ion batteries usually uses graphite, which has the advantages of low cost and low lithium insertion potential and abundant resources. However, there is a big problem with graphite electrodes. Its theoretical specific capacity is only 372mAh / g, which greatly limits the further development of high-capacity lithium-ion batteries. Therefore, the research on high-capacity negative electrode materials has great practical significance.

[0003] MXene was discovered in 2011 by Professor Yury Gogotsi and Professor Michel W. Barsoum of Drexel University in the United States. In their exploration of the MAX phase lithium storage performance, they put a MAX phase material, Ti3AlC2, into hydrofluoric acid and obtained a layered Ti3C2T x (T=-OH, -O, -F). MXene has received extensive attention due to its unique two-dimensional layered structure, metal-like conductivity and excellent mechanical properties. If MXene is simply used as the negative electrode of lithium-ion batteries, it also has certain limitations. The van der Waals force between MXene layers will cause serious layer stacking problems, thereby hindering the movement of lithium ions in MXene and affecting its rate performance and capacitance. Summary of the invention

[0004] In view of the deficiencies in the prior art, an object of the present invention is to provide a method for preparing a negative electrode material for a lithium ion battery.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing a negative electrode material for a lithium ion battery comprises the following steps:

[0007] LiF and hydrochloric acid are mixed and heated, and Ti3AlC2 material is added to the solution, and magnetic stirring is performed to obtain a mixed solution;

[0008] The mixed solution is centrifuged and washed, and LiCl solution is added, and the mixture is allowed to stand and then centrifuged again;

[0009] After centrifugation, the lower precipitate was removed and the sample was freeze-dried to obtain the sample MXene product;

[0010] The prepared Ti3C2MXene powder is added with water and stirred, and then BiCl3 test solution is added and stirred continuously, and after being mixed evenly, the mixture is filtered and film-formed, and a MXene composite film is obtained after drying;

[0011] The MXene composite film is placed in a NaBH4 solution for reaction, and is taken out and dried after the reaction to obtain a MXene / Bi composite material.

[0012] Furthermore, the hydrochloric acid is 11M hydrochloric acid.

[0013] Furthermore, the BiCl3 test solution is 0.1-0.5MBiCl3 test solution.

[0014] Furthermore, the NaBH4 solution is a 0.1M NaBH4 solution.

[0015] Furthermore, the LiF and hydrochloric acid are mixed and then heated, specifically heated in a 45° C. oil bath with stirring.

[0016] Furthermore, the magnetic stirring time is 12 hours.

[0017] A negative electrode material for a lithium-ion battery, wherein the negative electrode material is a MXene / Bi composite material.

[0018] The invention discloses an application of a lithium ion battery negative electrode material in a lithium ion battery.

[0019] Beneficial effects of the present invention:

[0020] 1. In the present invention, BiCl3 and NaBH4 are reacted to displace Bi nanoparticles and distribute them on the surface of MXene nanosheets, forming a relatively stable three-dimensional structure, which provides more attachment sites for Li storage. In addition, the presence of Bi can improve the lithium storage performance of MXene. The entire preparation process of MXene / Bi composite materials is short in time, which provides the possibility for large-scale production of battery negative electrode materials;

[0021] 2. The MXene / Bi composite material prepared in the present invention is used as a negative electrode material for lithium batteries and has the characteristics of high specific capacity, which effectively improves the lithium storage performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1is a scanning electron microscope image of the MXene / Bi composite material of the present invention;

[0024] Figure 2 is a characterization (XRD) diagram of the structure of Example 1 of the present invention;

[0025] Figure 3 This is a test diagram of the cycle performance of the electrode material of Example 2 of the present invention. DETAILED DESCRIPTION

[0026] 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.

[0027] The invention is constructed and operated in a specific orientation and therefore should not be construed as limiting.

[0028] A method for preparing a negative electrode material for a lithium-ion battery,

[0029] A lithium-ion negative electrode material is composed of Bi nanoparticles and MXene materials. The electron microscope image is as follows: Figure 1 As shown, from Figure 1 It can be obtained that MXene is in the form of nanosheets, the prepared Bi is in the form of nanoparticles, and the Bi nanoparticles are distributed on the surface of the MXene nanosheets to form the final MXene / Bi composite material. The entire composite material has a relatively stable three-dimensional structure, which can provide more reaction sites for the storage of Li ions and improve the lithium storage performance of the electrode material.

[0030] Example 1

[0031] A method for preparing a negative electrode material for a lithium-ion battery comprises the following steps:

[0032] a1, weigh 1g LiF, then measure 20ml 11M hydrochloric acid, mix, use 45℃ oil bath and stir in the oil bath for 10-15min, then add 1g Ti3AlC2 material, adjust the speed to 25rad / s, magnetically stir at 35℃, and react for 24h.

[0033] a2. After centrifugation for 3 times, add a mixed solution of 1.5 g LiCl and 30 ml deionized water into the centrifuge tube, let it stand for 1 hour, and then centrifuge it for 3 more times.

[0034] a3. After centrifugation, remove the lower precipitate and freeze-dry the sample for 24 hours to obtain MXene powder.

[0035] a4. Weigh 0.1 g of dry MXene and dissolve it in 0.1 M BiCl3 solution. After complete mixing, filter and form a membrane. Place the membrane in a vacuum drying oven and dry it for 12 hours to obtain a MXene film.

[0036] a5. Place the MXene film in 10 mL of 0.1 M NaBH4 solution and dry it after the reaction is completed.

[0037] Next, the MXene / Bi composite material obtained in Example 1 was evenly spread in the XRD sample groove wiped with alcohol, and then placed in the XRD instrument for X-ray polycrystalline diffraction to obtain Figure 2 Characterization (XRD) diagram of the structure shown. From the figure, it can be seen that after MXene and Bi particles are composited, the (002) crystal plane peak of MXene is basically invisible, but the diffraction peaks (012), (104), (110) and (202) belonging to Bi nanoparticles can be well observed, proving the existence of Bi particles.

[0038] Example 2

[0039] The preparation method of the negative electrode material of a lithium-ion battery and the lithium storage performance test include the following steps:

[0040] a1, weigh 1g LiF, then measure 20ml 11M hydrochloric acid, mix, use 45℃ oil bath and stir in the oil bath for 10-15min, then add 1g Ti3AlC2 material, adjust the speed to 25rad / s, magnetically stir at 35℃, and react for 24h.

[0041] a2. After centrifugation for 3 times, add a mixed solution of 1.5 g LiCl and 30 ml deionized water into the centrifuge tube, let it stand for 1 hour, and then centrifuge it for 3 more times.

[0042] a3, after centrifugation, the samples were freeze-dried for 24 h.

[0043] a4. Weigh 0.1 g of dry MXene and disperse it in 0.5 M BiCl3 solution. After complete mixing, filter and form a film. Place the film in a vacuum drying oven and dry it for 12 hours to obtain a MXene film.

[0044] a5. Place the MXene film in 20 mL of 0.1 M NaBH4 solution and react for 30 min. After the reaction is completed, dry it to obtain a MXene / Bi composite material.

[0045] The MXene / Bi composite material prepared in Example 2 and conventional negative electrode materials are used as negative electrodes of lithium-ion batteries to test the performance of lithium-ion batteries.

[0046] The test adopted the constant current charge and discharge method. The prepared MXene / Bi composite material, conductive agent, and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 7:2:1, and N-methylpyrrolidone (NMP) was used as the solvent. After stirring for 6 hours, it was evenly coated on the copper foil and dried under vacuum conditions at 120°C to obtain the electrode sheet. The electrolyte is 1M LiPF6 / ethylene carbonate (EC)-dimethyl carbonate (DMC) (volume ratio 1:1). The diaphragm is a polypropylene / polyethylene microporous membrane (Celgard2500), and all lithium-ion batteries are assembled in an anhydrous and oxygen-free glove box. The constant current charge and discharge method test was carried out on the NEWAREC 3008 multi-channel battery measurement device with a voltage range of 0.01~3.00V, and the cycle performance test chart of the MXene / Bi composite material of Example 2 was obtained. Figure 3 It can be obtained that under the condition of constant current density (0.5Ag-1), the initial charge and discharge capacity of the battery is 400mAhg-1, and its capacitance retention rate can still be maintained at more than 50% after 400 charge and discharge cycles.

[0047] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0048] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A method for preparing a negative electrode material for a lithium ion battery, characterized in that: The following steps are involved: LiF and hydrochloric acid are mixed and heated, and Ti3AlC2 material is added to the solution, and magnetic stirring is performed to obtain a mixed solution; The mixed solution is centrifuged and washed, and LiCl solution is added, and the mixture is allowed to stand and then centrifuged again; After centrifugation, the lower precipitate was removed and the sample was freeze-dried to obtain the sample MXene powder; The prepared MXene sample powder was stirred with water, and then BiCl3 test solution was added and continued to be stirred. After mixing evenly, the mixture was filtered to form a film, and then dried to obtain a MXene composite film. The MXene composite film is placed in a NaBH4 solution for reaction, and after the reaction, it is taken out and dried to obtain a MXene / Bi composite material; MXene is in the form of nanosheets, and the prepared Bi is in the form of nanoparticles. The Bi nanoparticles are distributed on the surface of the MXene nanosheets to form the final MXene / Bi composite material; The BiCl3 test solution is 0.1-0.5 mol / L BiCl3 test solution, and the NaBH4 solution is 0.1 mol / L NaBH4 solution; The hydrochloric acid is 11 mol / L hydrochloric acid; the LiF and the hydrochloric acid are mixed and then heated, specifically, heated in a 45° C. oil bath and stirred.

2. The method for preparing a negative electrode material for a lithium ion battery according to claim 1, characterized in that: The magnetic stirring time is 12 hours.

3. A negative electrode material for a lithium ion battery, characterized in that: The negative electrode material is prepared by the preparation method according to claim 1, and the negative electrode material is a MXene / Bi composite material.

4. Use of the lithium ion battery negative electrode material according to claim 3 in lithium ion batteries.

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