A method for preparing a negative electrode material for a lithium-ion battery

Abstract

The present invention provides a method for preparing a lithium-ion battery anode material, comprising: preparing a MXene material and CoNi-MOF; and synthesizing the lithium-ion battery anode material from the MXene material and the CoNi-MOF. The lithium-ion battery anode material obtained in this application can be used as a lithium-ion battery anode material, improving the battery's cycle stability and cycle life. When used as a lithium-ion battery anode material, it shortens the lithium ion transmission path and improves the material's conductivity. The prepared lithium-ion battery has the advantages of high stability, long cycle life, high rate performance, simple preparation process, inexpensive and readily available raw materials, low cost, and environmental friendliness, effectively meeting the practical application requirements of high-energy-density lithium-ion batteries.

Description

Technical Field

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

[0002] Due to the world's increasing energy demands and the rapid depletion of fossil fuels, the demand for efficient energy storage and conversion systems is growing rapidly. Lithium-ion batteries (LIBs) have achieved great success in various energy storage devices due to their high energy density, long cycle life, and environmental benefits. However, the rapidly increasing demand for energy is prompting the search for next-generation LIBs with even higher energy density. To achieve high-capacity LIBs, graphite-based anode materials offer significant advantages, including widespread application, wide availability, and economical efficiency. However, current commercial graphite carbon anode materials are limited by their low theoretical capacity (372 mAh g⁻¹), failing to meet the demand for high-capacity LIBs. Various advanced anode materials have been developed. Among these candidate materials, silicon-based materials hold the greatest potential due to their ultra-high theoretical capacity (4200 mAh g⁻¹), abundant reserves, low operating voltage, and low cost, making them a promising anode material for LIBs. However, during the lithiation / delithiation process, silicon suffers from large volume changes, unstable solid electrolyte interface (SEI) layer, and low conductivity, leading to rapid capacity fading, large irreversible capacity, and poor rate performance.

[0003] Metal-organic frameworks (MOFs) possess abundant energy storage active sites, good structural stability, and short ion migration channels, resulting in excellent electrochemical ion storage performance. Their scaffold-like, volume-packed, ordered structure provides a large surface area per unit mass / volume, with custom-designed pore spaces. This helps maximize stored energy density and also facilitates ion transport, thereby increasing power density.

[0004] MXene materials are usually obtained by etching the MAX phase. The surface area of ​​the MXene material after etching is increased, which can be used for Li + The number of active sites attached increases; its excellent conductivity accelerates the transfer of electrons, and at the same time, its Li + The diffusion barrier is lower than that of graphene, Li + Faster transport speeds and increased charge and discharge rates. Furthermore, their excellent mechanical properties effectively mitigate the volume changes caused by lithium insertion and extraction, maintaining a stable electrode structure. However, MXene materials are prone to restacking, resulting in reduced interlayer spacing and specific surface area, and their capacity as battery anode materials is relatively low.

[0005] Therefore, it is a technical challenge in this field to produce a method for preparing a lithium-ion battery negative electrode material with simple process, good cycle performance and rate charge and discharge performance, high and stable constant current charge and discharge efficiency, low impedance, which can increase the transmission speed of lithium ions and reduce costs during the production process. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing a negative electrode material for a lithium-ion battery, so as to solve the problem that the existing negative electrode of a lithium battery has low conductivity, resulting in rapid capacity fading, large irreversible capacity and poor rate performance.

[0007] The present invention provides a method for preparing a negative electrode material for a lithium ion battery, the method comprising:

[0008] Preparation of MXene materials and CoNi-MOF;

[0009] The MXene material and the CoNi-MOF are synthesized into a lithium-ion battery negative electrode material.

[0010] Furthermore, the preparation method of the MXene material includes:

[0011] S11, 3 ml of deionized water, 1 ml of HF, and 5 ml of HCl were added to a polytetrafluoroethylene autoclave, mixed with 1 g of 400-mesh Ti3AlC2 powder, and magnetically stirred in an oil bath for 15–24 h;

[0012] S12, washing with deionized water by centrifugation at 3500-4000 rpm for 1-5 minutes until the pH is ≥6;

[0013] S13, add 1.5 ml of LiCl powder into a beaker containing 25 ml of deionized water and dissolve;

[0014] S14, disperse the precipitate after centrifugation of S12 in the LiCl solution of S13, pour into a 50 ml round-bottom flask, and stir magnetically for 2-6 h;

[0015] S15, after washing 2-3 times with deionized water at 3500-4000 rpm for 5 minutes, the supernatant was discarded, and the mixture was collected by centrifugation at 3500-4000 rpm for 5 minutes. Ti3C2T x suspension.

[0016] Furthermore, the preparation method of the CoNi-MOF includes:

[0017] S21, mixing Co(OAc)2·4H2O, Ni(OAc)2·4H2O, 2,3,6,7,10,11-hexahydroxytriphenylenebenzene, and H2O, wherein the molar ratio of Co(OAc)2·4H2O, Ni(OAc)2·4H2O, 2,3,6,7,10,11-hexahydroxytriphenylenebenzene, and H2O is 1:1:1:0.4, and ultrasonicating until dispersed;

[0018] S22, placing the mixed solution after ultrasonic dispersion in S21 into a glass bottle, then placing the glass bottle in an oven for heating, and then naturally cooling to room temperature;

[0019] S23, after obtaining a solid by suction filtration, washing it with deionized water and ethanol respectively, and heating and drying it in a vacuum drying oven overnight, finally obtaining the CoNi-MOF.

[0020] Furthermore, the step of synthesizing the negative electrode material of a lithium-ion battery by combining the MXene material and the CoNi-MOF comprises:

[0021] S31, mixing Co(OAc)2·4H2O, Ni(OAc)2·4H2O, Ti3C2Tx and H2O in a mass ratio of 1:1:0.25:0.4, and sonicating until dispersed;

[0022] S32, mixing 2,3,6,7,10,11-hexahydroxytriphenylenebenzene and 4-6 ml of H2O, wherein the mass ratio of the 2,3,6,7,10,11-hexahydroxytriphenylenebenzene to H2O is 7:2, and ultrasonicating until dispersed;

[0023] S33, placing the dispersions obtained by ultrasonic dispersion in S31 and S32 into a glass bottle, then placing the glass bottle in an oven for heating, and then naturally cooling to room temperature;

[0024] S34, after obtaining the solid by suction filtration, washing it with deionized water and ethanol respectively, and heating and drying it in a vacuum drying oven overnight, finally obtaining a lithium battery negative electrode material.

[0025] Furthermore, in S11, the temperature of the oil bath is 41-45°C and the stirring speed is 500-600 rpm.

[0026] Furthermore, in S14, the stirring condition at room temperature is 500-600 rpm.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] 1. Metal-organic frameworks (MOFs) have abundant energy storage active sites, good structural stability and short ion migration channels, and have excellent electrochemical ion storage performance. Their scaffold-shaped volume-filling ordered structure can provide a large unit mass / volume specific surface area with custom-designed pore space, which helps to maximize the stored energy density; it can also promote ion transport, thereby increasing power density.

[0029] 2. The electrode performance of MOF materials is improved by combining MXene materials with CoNi-MOF materials. Its multi-level pore structure greatly reduces the diffusion barrier of lithium ions in CoNi-MOF and improves the transmission efficiency of lithium ions and electrons between electrodes. CoNi-MOF is embedded between MXene layers to prevent the stacking of MXene material layers, ensuring the stability of its layered structure and greatly improving the cycle performance of the electrode material. After the CoNi-MOF and MXene materials are combined, the electrochemical performance of the composite material is greatly improved.

[0030] 3. The lithium-ion battery negative electrode material obtained in this application can be used as a lithium-ion battery negative electrode material to improve the battery's cycle stability and cycle life; when it is used as a lithium-ion battery negative electrode material, the lithium ion transmission path is shortened and the material conductivity is improved; the prepared lithium-ion battery has the advantages of high stability, long cycle life, high rate performance, simple preparation process, cheap and easy-to-obtain raw materials, low cost, and good environmental protection, which can effectively meet the actual application needs of high-energy-density lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the SEM image of the CoNi-MOF prepared by the invention.

[0032] Figure 2 This is the TEM image of the CoNi-MOF prepared by the invention.

[0033] Figure 3 This is the charge and discharge curve of the CoNi-MOF prepared by the invention.

[0034] Figure 4 This is the specific capacity cycle diagram of the CoNi-MOF prepared by the invention.

[0035] Figure 5 This is the magnification diagram of the CoNi-MOF prepared by the invention.

[0036] Figure 6 This is an SEM image of the lithium-ion battery negative electrode material prepared by the invention.

[0037] Figure 7 This is a TEM image of the invented lithium-ion battery negative electrode material.

[0038] Figure 8 It is a charge and discharge curve diagram of the lithium-ion battery negative electrode material prepared by the invention.

[0039] Figure 9 This is a specific capacity cycle diagram of the invented and prepared lithium-ion battery negative electrode material.

[0040] Figure 10 This is a rate diagram of the lithium-ion battery negative electrode material prepared by the invention.

[0041] Figure 11 This is the SEM image of MXene material.

[0042] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0043] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0044] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0046] Example 1

[0047] A method for preparing a negative electrode material for a lithium-ion battery comprises the following steps:

[0048] Preparation of MXene materials and CoNi-MOF;

[0049] The MXene material and the CoNi-MOF are synthesized into a lithium ion battery negative electrode material

[0050] Synthesis of MXene

[0051] Specifically, 1g of 400-mesh Ti3AlC2 powder was added to a polytetrafluoroethylene autoclave, mixed with 3H2O, 1-20ml HF, and 5ml HCl. After magnetic stirring in an oil bath for 15-24 hours, the mixture was washed with deionized water by centrifugation at 3500-4000rpm for 1 minute until the pH was ≥6. 1.5g of LiCl powder was added to a beaker containing 25ml of deionized water to dissolve. The LiCl solution and the precipitate after centrifugation were then dispersed and poured into a 50ml round-bottom flask. After magnetic stirring for 2-6 hours, the mixture was washed two or three times with deionized water by centrifugation at 3500-4000rpm for 5 minutes. The supernatant was discarded and the suspension was collected by centrifugation at 3500-4000rpm for 5 minutes. The Ti3C2Tx suspension was evenly layered 5-8 times. This is how MXene materials are synthesized.

[0052] Synthesis of CoNi-MOF:

[0053] 0.04mmol Co(OAc)2·4H2O, 0.04mmol Ni(OAc)2·4H2O, 0.042mmol 2,3,6,7,10,11-hexahydroxytriphenylenebenzene, and 8H2O were mixed and ultrasonicated for 30 minutes to disperse. The mixed solution was placed in a 20ml glass bottle, which was then placed in an oven and kept at 85-100°C for 12-24 hours, then naturally cooled to room temperature. After the solid was obtained by suction filtration, it was washed with deionized water and ethanol 3-5 times respectively, and dried in a vacuum oven at 60-80°C overnight to finally obtain the CoNi-MOF anode material.

[0054] Synthesis of lithium-ion battery anode materials

[0055] 0.04mmol Co(OAc)2·4H2O, 0.04mmol Ni(OAc)2·4H2O, 1ml Ti3C2Tx, and 4ml H2O were added to a 20ml glass bottle, mixed, and sonicated for 15 minutes until dispersed. 0.042mmol 2,3,6,7,10,11-hexahydroxytriphenylenebenzene and 4ml H2O were added, mixed, and sonicated for 30 minutes until dispersed. The two sonicated dispersions were then placed together in a 20ml glass bottle, which was then placed in an oven and maintained at 85-100°C for 12-24 hours before naturally cooling to room temperature. The solid was filtered, washed 3-5 times with deionized water and ethanol, respectively, and dried in a vacuum oven at 60-80°C overnight to produce the lithium-ion battery negative electrode material.

[0056] Example 2

[0057] Synthesis of MXene

[0058] Add 1g 400-mesh Ti3AlC2 powder to a polytetrafluoroethylene autoclave, mix with 3ml H2O, 1ml HF and 5ml HCl, and stir magnetically in an oil bath for 15 to 24 hours. Use deionized water to centrifuge at 3500-4000rpm for 1 to 5 minutes to wash until the pH is ≥ 6. Add 1.5g LiCl powder to a beaker filled with 25ml deionized water to dissolve, then disperse the LiCl solution with the precipitate after centrifugation, pour into a 50ml round-bottom flask, and stir magnetically for 2 to 6 hours. Use deionized water to centrifuge at 3500-4000rpm for 5 minutes to wash 2 to 3 times, then pour out the supernatant, and then use 3500-4000rpm to centrifuge for 5 minutes to start collecting, and collect 5 to 8 evenly layered Ti3C2Tx suspensions.

[0059] Synthesis of CoNi-MOF

[0060] 0.04mmol Co(OAc)2·4H2O, 0.04mmol Ni(OAc)2·4H2O, 0.042mmol 2,3,6,7,10,11-hexahydroxytriphenylenebenzene, and 8ml H2O were mixed and ultrasonicated for 30 minutes to disperse. The mixed solution was placed in a 20ml glass bottle, which was then placed in an oven and kept at 85-100°C for 12-24 hours, then naturally cooled to room temperature. After the solid was obtained by suction filtration, it was washed with deionized water and ethanol 3-5 times respectively, and dried in a vacuum drying oven at 60-80°C overnight to finally obtain the CoNi-MOF anode material.

[0061] Synthesis of lithium-ion battery anode materials

[0062] 0.04 mmol Co(OAc)2·4H2O, 0.04 mmol Ni(OAc)2·4H2O, 1 ml Ti3C2Tx, 0.042 mmol 2,3,6,7,10,11-hexahydroxytriphenylenebenzene, and 8 ml H2O were added to a 20 ml glass bottle, mixed, and ultrasonicated for 30 minutes until dispersed. The glass bottle was then placed in an oven and maintained at 85-100°C for 12-24 hours before being naturally cooled to room temperature. The solid was filtered and washed 3-5 times with deionized water and ethanol, respectively, and dried in a vacuum oven at 60-80°C overnight to produce the lithium-ion battery negative electrode material.

[0063] Example 3

[0064] Synthesis of MXene

[0065] Add 1g 400-mesh Ti3AlC2 powder to a polytetrafluoroethylene autoclave, mix with 3ml H2O, 1ml HF and 5ml HCl, and stir magnetically in an oil bath for 15 to 24 hours. Use deionized water to centrifuge at 3500-4000rpm for 1 to 5 minutes to wash until the pH is ≥ 6. Add 1.5g LiCl powder to a beaker filled with 25ml deionized water to dissolve, then disperse the LiCl solution with the precipitate after centrifugation, pour into a 50ml round-bottom flask, and stir magnetically for 2 to 6 hours. Use deionized water to centrifuge at 3500-4000rpm for 5 minutes to wash 2 to 3 times, then pour out the supernatant, and then use 3500-4000rpm to centrifuge for 5 minutes to start collecting, and collect 5 to 8 evenly layered Ti3C2Tx suspensions.

[0066] Synthesis of CoNi-MOF

[0067] 0.04mmol Co(OAc)2·4H2O, 0.04mmol Ni(OAc)2·4H2O, 0.042mmol 2,3,6,7,10,11-hexahydroxytriphenylenebenzene, and 8ml H2O were added to a 50ml round-bottom flask, mixed, and ultrasonicated for 30 minutes until dispersed. The round-bottom flask was then placed in an oil bath and heated with stirring at 85-100°C for 12-24 hours, then naturally cooled to room temperature. The solid was then filtered and washed 3-5 times with deionized water and ethanol, respectively, and dried in a vacuum oven at 60-80°C overnight to obtain the CoNi-MOF anode material.

[0068] Synthesis of lithium-ion battery anode materials

[0069] 0.04 mmol Co(OAc)2·4H2O, 0.04 mmol Ni(OAc)2·4H2O, 1 ml Ti3C2Tx, 0.042 mmol 2,3,6,7,10,11-hexahydroxytriphenylenebenzene, and 8 ml H2O were added to a 50 ml round-bottom flask, mixed, and sonicated for 30 minutes until dispersed. The round-bottom flask was then placed in an oil bath and heated with stirring at 85-100°C for 12-24 hours, then cooled naturally to room temperature. The solid was filtered, washed 3-5 times with deionized water and ethanol, respectively, and dried overnight in a vacuum oven at 60-80°C to produce the lithium-ion battery anode material.

[0070] The lithium-ion battery negative electrode materials prepared in Examples 1 to 3 of the present invention have similar performances and similar effects. The following study is conducted using Example 1 as an example. The specific research methods and results are as follows:

[0071] The CoNi-MOF and lithium-ion battery negative electrode materials of Example 1 were assembled into a button half-cell for electrochemical performance testing. The button cell assembly steps were as follows: adding the active material lithium-ion battery negative electrode material, conductive carbon black, and polytetrafluoroethylene to N-methylpyrrolidone in a mass ratio of 7:2:1 and mixing them evenly to prepare an electrode slurry; coating the slurry on a copper foil with a thickness of 9 μm and drying it in a vacuum oven at 60°C for 12 h to prepare an electrode piece, and assembling the electrode piece and metallic lithium into a button half-cell in an argon-filled glove box. The button cell was subjected to a performance test at a rate of 0.2C using a LAND battery test system:

[0072] Figure 1-5 The SEM image, TEM image, charge and discharge curve, cycle diagram and rate diagram of the CoNi-MOF negative electrode material prepared in Example 1 are shown. Figure 1 It can be seen that the structure of CoNi-MOF is a rod-like structure with more active sites. The results show that the CoNi-MOF negative electrode material of Example 1 was subjected to a buckle test. The capacity was the largest at the time of the first discharge, and the irreversible loss of capacity was mainly attributed to the formation of the SEI film and the continuous decomposition of the electrolyte in the first cycle. It began to stabilize afterwards. It has excellent electrochemical lithium storage stability. After 100 cycles, the specific capacity is 618.7mAh / g. As shown in the rate graph, it has good reversible performance from low rate to high rate and then to low rate.

[0073] Figure 6-10 The SEM (scanning electron microscope) image, TEM (transmission electron microscope) image, charge and discharge curve graph, cycle graph and rate graph of the lithium ion battery negative electrode material prepared in Example 1. Figure 6 It can be seen that CoNi-MOF grows inside or on the surface of the MXene material. The results show that when the lithium-ion battery negative electrode material of Example 1 is subjected to a buckle test, the capacity is also the largest at the time of the first discharge. The irreversible loss of capacity is mainly attributed to the formation of the SEI film (Solid Electrolyte Interface membrane, which is a passivation layer formed by the chemical reaction of the electrolyte on the electrode surface during the charge and discharge process of the lithium-ion battery) and the continuous decomposition of the electrolyte in the first cycle. It began to stabilize afterwards. It has excellent electrochemical lithium storage stability. After 100 cycles, the specific capacity is 637.2mAh / g. As shown in the rate graph, it has good reversible performance from low rate to high rate and then to low rate.

[0074] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a negative electrode material for a lithium ion battery, characterized in that: The method comprises: Preparation of MXene materials and CoNi-MOF; The MXene material and the CoNi-MOF are synthesized into a lithium-ion battery negative electrode material; The step of synthesizing the negative electrode material of a lithium-ion battery by combining the MXene material and the CoNi-MOF comprises: S31, mixing Co(OAc)2·4H2O, Ni(OAc)2·4H2O, Ti3C2Tx and H2O in a mass ratio of 1:1:0.25:0.4, and sonicating until dispersed; S32, mixing 2,3,6,7,10,11-hexahydroxytriphenylenebenzene and 4-6 ml of H2O, wherein the mass ratio of the 2,3,6,7,10,11-hexahydroxytriphenylenebenzene to H2O is 7:2, and ultrasonicating until dispersed; S33, placing the dispersions obtained by ultrasonic dispersion in S31 and S32 into a glass bottle, then placing the glass bottle in an oven for heating, and then naturally cooling to room temperature; S34, after obtaining the solid by suction filtration, washing it with deionized water and ethanol respectively, and heating and drying it in a vacuum drying oven overnight, finally obtaining a lithium battery negative electrode material.

2. The method for preparing a negative electrode material for a lithium ion battery according to claim 1, wherein: The preparation method of the MXene material comprises: S11, adding deionized water, HF and HCl into an autoclave and mixing with Ti3AlC2 powder, wherein the volume ratio of deionized water, HF, HCl and Ti3AlC2 is 3:1:5:0.2 or 1:2:2:0.04, and magnetically stirring in an oil bath; S12, centrifugation and washing with deionized water until the pH is ≥ 6; S13, adding LiCl powder to a beaker filled with deionized water to dissolve, wherein the mass ratio of LiCl to deionized water is 1.5:25; S14, disperse the precipitate after centrifugation in S12 in the LiCl solution in S13, pour into a round-bottom flask, and stir magnetically; S15, after centrifugal washing with deionized water, the supernatant is poured out, and centrifugation is started again to collect the uniformly layered Ti3C2Tx suspension.

3. The method for preparing a negative electrode material for a lithium ion battery according to claim 2, wherein: In S11, the oil bath temperature is 41 to 45°C and the stirring speed is 500 to 600 rpm.

4. The method for preparing a negative electrode material for a lithium ion battery according to claim 2, wherein: In S14, the stirring condition at room temperature is 500 to 600 rpm.

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