Lithium-ion battery electrode material and preparation method thereof

Abstract

A method for preparing a lithium-ion battery electrode material belongs to the field of new energy material technology and includes preparing a MOF material, pretreating the MOF material, and selenizing the MOF material. The MOF material pretreatment comprises immersing the MOF material in a mixed aqueous solution of glucose and alkyl glycoside, and maintaining the solution at 70-90°C for 0.5-1 hour. The mass ratio of glucose to alkyl glycoside in the mixed aqueous solution is 4:0.5-1. The carbon-based electrode material prepared by the present invention is a uniformly dispersed cubic shape, effectively alleviating the volume expansion effect. The carbon-based electrode material has a purity of up to 99.3%. As an electrode material for lithium-ion batteries in new energy vehicles, it has excellent lithium storage performance and cycle stability, with a charge-discharge rate of 100 mA g ‑1 After 200 charge and discharge cycles at a current density of 1.5 GHz, the discharge capacity is 662 mAh g ‑1 The charging and discharging performance is stable during the cycle, and there will be no current fluctuations. The cycle life is long and the performance can be recycled 1,000 times without degradation, which broadens the choice for improving the endurance of new energy vehicles.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy materials, and in particular to a lithium-ion battery electrode material and a preparation method thereof. Background Art

[0002] Lithium-ion batteries are widely used in mobile electronic devices, new energy vehicles and other fields due to their advantages such as high energy density, long cycle life and environmental friendliness.

[0003] However, the negative electrode material of commercial lithium-ion batteries is usually graphite. However, the theoretical capacity of graphite is only 372mAh / g, which cannot meet the needs of high-performance lithium-ion batteries. Therefore, people have launched a series of research on high-energy lithium-ion battery negative electrode materials, such as transition metal oxides, transition metal sulfides, and transition metal selenides. Compared with transition metal oxides and transition metal sulfides, transition metal selenides not only have a high theoretical specific capacity, but also have a low voltage platform and small polarization, making them a promising negative electrode material for lithium-ion batteries. However, during the charge and discharge process, transition metal selenides undergo huge volume changes due to the insertion and extraction of lithium ions, which causes the active material to pulverize and separate from the current collector, resulting in capacity decay and poor material cycle life and stability. In addition, transition metal selenides have poor conductivity, which hinders the rapid transfer of electrons within the active material.

[0004] Bimetallic selenides are currently attracting significant attention as battery electrode materials due to their lower band gap and improved conductivity compared to single-metal selenides. However, the morphology and structure of bimetallic selenides significantly influence their electrochemical performance. For example, different structures of the same material, such as nanowires, nanosheets, nanotubes, and nanospheres, exhibit distinct electrochemical properties. The lithium storage capacity and cycling stability of the electrode material play a decisive role in its application in the automotive field, affecting the vehicle's endurance and stability. Summary of the Invention

[0005] Based on the above technical problems, the present invention aims to provide a lithium-ion battery electrode material, specifically a cubic carbon-based composite material composed of cubic selenide and carbon.

[0006] Another object of the present invention is to provide a method for preparing the aforementioned lithium-ion battery electrode material. The selenide-carbon-based composite material prepared by this method exhibits uniform morphology, excellent dimensional uniformity, and excellent dispersibility. The carbon material completely encapsulates the bimetallic selenide, effectively suppressing volume expansion. The composite material can be effectively applied to new energy vehicles as the negative electrode material for lithium-ion batteries in these vehicles.

[0007] The object of the present invention is achieved through the following technical solutions:

[0008] A method for preparing a lithium-ion battery electrode material, characterized by comprising the steps of preparing a MOF material, pretreating the MOF material, and selenization treatment. The MOF material pretreatment comprises immersing the MOF material in a mixed aqueous solution of glucose and alkyl glycoside, keeping the temperature at 70-90° C. for 0.5-1 hour, and then drying.

[0009] The mass percentage concentration of glucose in the mixed aqueous solution is 20-40%, and the mass ratio of glucose to alkyl glycoside is 4:0.5-1.

[0010] Furthermore, the selenium treatment is to place the pretreated MOF material and selenium powder in a tubular furnace, with the selenium powder upstream and the MOF material downstream, and heat the material to 400-450°C at a rate of 2-5°C / min under an argon atmosphere, and keep it warm for 1.5-2.5 hours. During this process, the argon flow rate is 45-60 sccm, and then continue to heat to 550-600°C and keep it warm for 0.5-1 hour. During this process, the argon flow rate is 30-40 sccm.

[0011] If the specific surface area of ​​the electrode material is too small, the material's rate performance will be poor, and the cycle performance will also be poor. Therefore, increasing the specific surface area of ​​the material to a certain extent is beneficial to improving the performance of the electrode material. Cubic bimetallic selenide composite materials have a high specific surface area, which can effectively improve the electrochemical performance of the material. However, since cubic MOF materials have both planes and edges, it is difficult to ensure the stability of their cubic structure during high-temperature selenization. During the selenization process, the organic ligands are easily carbonized, which leads to structural fracture, resulting in the collapse of the cubic structure. The structure is also prone to agglomeration, and the final morphology is damaged and irregular. The formed carbon material is also difficult to completely wrap the bimetallic selenide formed by selenization. When the prepared material is used as an electrode material, it will face a serious volume expansion effect during the charge and discharge process, resulting in a decrease in the material's electrochemical performance such as cycle stability and service life. In addition, some metal compound impurities other than MoSe2 and CoSe2 are easily generated during the selenization process, and the purity is low, resulting in material performance that does not meet expectations.

[0012] The cubic MnCo-MOF material prepared in the present invention is pretreated by heating and soaking in a high-concentration mixed aqueous solution of glucose and alkyl glycoside before selenization, and then undergoes a step-by-step selenization treatment. During the soaking process, under the action of alkyl glycoside and heating, glucose slowly penetrates into the interior of the MnCo-MOF material. During the subsequent selenization, the alkyl glycoside and glucose that have penetrated into the interior of the MnCo-MOF material simultaneously change the interfacial properties of the MnCo-MOF material, stabilize the template effect of the MnCo-MOF material, and effectively suppress the problems of structural rupture, collapse, and agglomeration during the selenization process. While the alkyl carbon sugar and glucose are carbonized, they generate a mutual pulling force with the organic ligand, inducing it to be evenly coated on the surface of the bimetallic selenide during the carbonization process, forming a complete coating.

[0013] During the selenization treatment, the present invention performs the first selenization at 400-450° C. and then performs the second selenization at 550-600° C., adjusts the argon gas flow rate during the two-step selenization process, and regulates the selenization process, thereby effectively reducing the generation of impurities during the selenization process. At the same time, under the above-mentioned selenization treatment, the interaction between the alkyl glycoside, glucose and the organic ligand during the carbonization process is regulated, thereby improving the coating integrity of the carbon material on the metal selenide.

[0014] In the above-mentioned cubic bimetallic selenides, Mn-based selenides can react to produce a variety of intermediate manganese ions to form different intermediate phases. Co-based selenides react with Li-ion in batteries. + An alloying reaction occurs, and the two metal elements provide more reactive sites through the reaction, thereby increasing the lithium storage performance. In the cubic structure, they act as buffer matrices for each other, effectively alleviating the volume effect caused by charging and discharging. The carbon layer uniformly and completely coated on the surface, combined with the specific cubic structure, further reduces the volume expansion and improves the conductivity of the material, showing excellent lithium ion cycle stability. These properties are useful for optimizing the electrochemical performance of lithium ion batteries when the material is used as an electrode material for lithium ion batteries in new energy vehicles, thereby effectively improving the endurance and stability of new energy vehicles.

[0015] Furthermore, the MOF material is prepared by dissolving Mn(CH3COO)2·4H2O and PVP-K30 in a mixed solvent consisting of anhydrous ethanol and deionized water to obtain solution A, dissolving K3Co(CN)6 in deionized water to obtain solution B, and mixing solution A and solution B and aging at room temperature to obtain MnCo-MOF material.

[0016] Furthermore, in the solution A, the mass ratio of Mn(CH3COO)2·4H2O and PVP-K30 is 0.22~0.44:0.75~3, the mass volume ratio of Mn(CH3COO)2·4H2O and the mixed solvent is 0.1~0.5:100, in g / mL, and the volume ratio of anhydrous ethanol to deionized water is 2:1.

[0017] Furthermore, in the solution B, the mass volume ratio of K3Co(CN)6 to deionized water is 0.13~0.68:100, and the unit is g / mL.

[0018] Furthermore, the above solution A and solution B are mixed in a molar ratio of Mn to Co of 1.2 to 1.8:1 and aged at room temperature for 15 to 26 hours.

[0019] Most specifically, a method for preparing a lithium-ion battery electrode material is characterized by comprising the following steps:

[0020] (1) Synthesis of MnCo-MOF materials

[0021] Mn(CH3COO)2·4H2O and PVP-K30 were dissolved in a mixed solvent consisting of anhydrous ethanol and deionized water to obtain solution A, and K3Co(CN)6 was dissolved in deionized water to obtain solution B. Solution A and solution B were mixed according to a molar ratio of Mn to Co of 1.2 to 1.8:1, aged at room temperature for 15 to 26 hours, and the precipitate was collected by centrifugation, washed with ethanol and deionized water in sequence, and then dried to obtain MnCo-MOF. In the solution A, The mass ratio of Mn(CH3COO)2·4H2O and PVP-K30 is 0.22~0.44:0.75~3, the mass volume ratio of Mn(CH3COO)2·4H2O and the mixed solvent is 0.1~0.5:100, the unit is g / mL, the volume ratio of anhydrous ethanol and deionized water is 2:1, and in the solution B, the mass volume ratio of K3Co(CN)6 and deionized water is 0.13~0.68:100, the unit is g / mL;

[0022] (2) Preprocessing

[0023] The MnCo-MOF material is immersed in a mixed aqueous solution of glucose and alkyl glycoside, kept at 70-90°C for 0.5-1h, and then dried, wherein the mass percentage concentration of glucose in the mixed aqueous solution is 20-40%, and the mass ratio of glucose to alkyl glycoside is 4:0.5-1;

[0024] (3) Selenization treatment

[0025] The pretreated MnCo-MOF material and selenium powder were placed in a tubular furnace with selenium powder upstream and MnCo-MOF material downstream. Under an argon atmosphere, the temperature was raised to 400-450°C at a rate of 2-5°C / min and kept warm for 1.5-2.5 hours. During this process, the argon flow rate was 45-60 sccm. Then the temperature was continued to be raised to 550-600°C and kept warm for 0.5-1 hour. During this process, the argon flow rate was 30-40 sccm to obtain a MnSe2 / CoSe2 / C composite material.

[0026] A lithium-ion battery electrode material, characterized in that the electrode material is a composite material composed of cubic selenide and carbon, the carbon material is coated on the surface of the bimetallic selenide, and the composite material is a MnSe2 / CoSe2 / C composite material obtained by pre-treating the MnCo-MOF material as a precursor and then performing selenization treatment.

[0027] Furthermore, the MnCo-MOF material is prepared by dissolving Mn(CH3COO)2·4H2O and PVP-K30 in a mixed solvent consisting of anhydrous ethanol and deionized water to obtain solution A, and dissolving K3Co(CN)6 in deionized water to obtain solution B. Solution A and solution B are mixed and aged at room temperature to prepare MnCo-MOF.

[0028] Furthermore, in the solution A, the mass ratio of Mn(CH3COO)2·4H2O and PVP-K30 is 0.22~0.44:0.75~3, the mass volume ratio of Mn(CH3COO)2·4H2O and the mixed solvent is 0.1~0.5:100, in g / mL, and the volume ratio of anhydrous ethanol to deionized water is 2:1.

[0029] Furthermore, in the solution B, the mass volume ratio of K3Co(CN)6 to deionized water is 0.13~0.68:100, and the unit is g / mL.

[0030] Furthermore, the solution A and the solution B are mixed in a molar ratio of Mn to Co of 1.2 to 1.8:1 and aged at room temperature for 15 to 26 hours.

[0031] Furthermore, the pretreatment is to immerse the MnCo-MOF material in a mixed aqueous solution of glucose and alkyl glycoside, keep it warm at 70-90°C for 0.5-1h, and then dry it. The mass percentage concentration of glucose in the mixed aqueous solution is 20-40%, and the mass ratio of glucose to alkyl glycoside is 4:0.5-1.

[0032] Furthermore, the selenium treatment is to place the pretreated MnCo-MOF material and selenium powder in a tubular furnace, with the selenium powder upstream and the MnCo-MOF material downstream, and heat the material to 400-450°C at a rate of 2-5°C / min under an argon atmosphere, and keep it warm for 1.5-2.5 hours. During this process, the argon flow rate is 45-60 sccm, and then continue to heat the material to 550-600°C and keep it warm for 0.5-1 hour. During this process, the argon flow rate is 30-40 sccm.

[0033] The present invention has the following technical effects:

[0034] The MnSe2 / CoSe2 / C composite material of the present invention exhibits a uniform cubic structure with uniform morphology and size, excellent dispersion, and high purity (up to 99.3%). The carbon layer completely encapsulates the bimetallic selenide. It exhibits excellent electrical conductivity and cycling stability, making it suitable for use as the negative electrode material for lithium-ion batteries in new energy vehicles.

[0035] The preparation method of the present invention solves the problems of easy collapse and poor structural stability of the cubic structure during the selenization process, the problem of a large number of impurities during the refinement process, and the problem of poor coating performance of bimetallic selenide of the cubic structure of carbon materials and easy agglomeration. The carbon-based electrode material prepared by the present invention has excellent structural stability and is in a uniformly dispersed cubic shape. The carbon layer completely coats the bimetallic selenide, effectively alleviating the volume expansion effect. The purity of the composite material is as high as 99.3%. When used as a negative electrode material for lithium-ion batteries of new energy vehicles, the carbon-based electrode material has excellent lithium storage performance and cycle stability. At 100 mA g -1 After 200 charge and discharge cycles at a current density of 1.5 GHz, the discharge capacity is 662 mAh g -1 The charging and discharging performance is stable during the cycle, and there will be no current fluctuations. The cycle life is long. During 1,000 cycles, the performance has not decayed, which broadens the options for improving the endurance of new energy vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 : XRD pattern of the cubic MnSe2 / CoSe2 / C composite material prepared in Example 1 of the present invention.

[0037] Figure 2 : SEM image of the cubic MnSe2 / CoSe2 / C composite material prepared in Example 1 of the present invention.

[0038] Figure 3 : TEM image of the cubic MnSe2 / CoSe2 / C composite material prepared in Example 1 of the present invention.

[0039] Figure 4 : SEM images of the composite materials prepared in each comparative example.

[0040] Figure 5 : Raman image of the cubic MnSe2 / CoSe2 / C composite material prepared in Example 1 of the present invention.

[0041] Figure 6 : TGA graph of the cubic MnSe2 / CoSe2 / C composite material prepared in Example 1 of the present invention.

[0042] Figure 7 : CV diagram of the cubic MnSe2 / CoSe2 / C composite material prepared in Example 1 of the present invention.

[0043] Figure 8 : EIS graph of the cubic MnSe2 / CoSe2 / C composite material prepared in Example 1 of the present invention.

[0044] Figure 9 : Charge and discharge cycle diagram of the cubic MnSe2 / CoSe2 / C composite material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0045] The present invention is described in detail below through examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above-mentioned contents of the present invention.

[0046] Example 1

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

[0048] (1) Synthesis of MnCo-MOF materials

[0049] Mn(CH3COO)2·4H2O and PVP-K30 were dissolved in a mixed solvent of anhydrous ethanol and deionized water to obtain solution A, and K3Co(CN)6 was dissolved in deionized water to obtain solution B. Solution A and solution B were mixed at a molar ratio of Mn to Co of 1.5:1 and aged at room temperature for 20 h. The precipitate was collected by centrifugation, washed with ethanol and deionized water in sequence, and then dried to obtain MnCo-MOF. In the solution A, the mass ratio of Mn(CH3COO)2·4H2O and PVP-K30 was 0.40:0.75~3, the mass volume ratio of Mn(CH3COO)2·4H2O to the mixed solvent was 0.1~0.5:100, expressed in g / mL, and the volume ratio of anhydrous ethanol to deionized water was 2:1. In the solution B, the mass volume ratio of K3Co(CN)6 to deionized water was 0.13~0.68:100, expressed in g / mL;

[0050] (2) Preprocessing

[0051] The MnCo-MOF material was immersed in a mixed aqueous solution of glucose and alkyl glycoside, kept warm at 70-90°C for 0.5-1h, and then dried. The mass percentage concentration of glucose in the mixed aqueous solution was 30%, and the mass ratio of glucose to alkyl glycoside was 4:0.5-1;

[0052] (3) Selenization treatment

[0053] The pretreated MnCo-MOF material and selenium powder were placed in a tubular furnace with selenium powder upstream and MnCo-MOF material downstream. Under an argon atmosphere, the temperature was raised to 420°C at a rate of 5°C / min and kept warm for 2 hours. During this process, the argon flow rate was 50 sccm. Then the temperature was continued to be raised to 580°C and kept warm for 0.5 hours. During this process, the argon flow rate was 35 sccm to obtain a MnSe2 / CoSe2 / C composite material.

[0054] Figure 1 From the XRD pattern of the MnSe2 / CoSe2 / C composite material prepared in this embodiment, it can be seen that the prepared composite material has obvious characteristic peaks and high purity. After calculation, the purity of the MnSe2 / CoSe2 / C composite material reaches 99.3%, the impurity content is low, and the yield also reaches 77.8%.

[0055] Figure 2 and Figure 3 The scanning electron microscopy and transmission electron microscopy images of the MnSe2 / CoSe2 / C composite material prepared in this embodiment are respectively Figure 2 It can be seen that the composite material is uniformly dispersed and has a regular cubic structure with uniform structural size. The surface is evenly covered with a dense carbon layer, which makes the surface of the material have a uniform rough structure. Figure 3It can be observed that a uniform carbon layer forms a complete coating on the surface of the bimetallic selenide.

[0056] Figure 5 This is the Raman spectrum of the MnSe2 / CoSe2 / C composite prepared in this example. The ratio of the D and G peak intensities, i.e., ID / IG, is greater than 1, indicating that the MnSe2 / CoSe2 / C composite has a dominant disordered carbon content, which is more conducive to lithium ion storage.

[0057] Figure 6 This is the TGA graph of the MnSe2 / CoSe2 / C composite material prepared in this example. o There are two steps of continuous mass loss in the MnSe2 / CoSe2 / C composite within the C range. This mass loss is caused by the combustion of carbon in air.

[0058] Figure 7 The CV curves of the MnSe2 / CoSe2 / C composite material prepared in this example are shown in Figure 2. The second and third CV curves have good overlap, indicating that the MnSe2 / CoSe2 / C composite material has high reversibility in lithiation / delithiation reactions.

[0059] The MnSe2 / CoSe2 / C composite material prepared in this embodiment well maintains the cubic morphology of the binary metal organic framework compound, has high crystallinity, high specific surface area and porosity, and exhibits excellent lithium storage performance, large storage capacity, long cycle life, and can be cycled at least 1000 times without performance degradation. It has good stability during use and will not experience current fluctuations. Figure 9 As shown, at 100 mA g -1 After 200 charge and discharge cycles at a current density of 1.5 GHz, the discharge capacity still reached 662 mAh g -1 . As a new energy vehicle, lithium-ion batteries have excellent lithium storage performance and charge and discharge cycle stability.

[0060] Comparative Example 1

[0061] Compared with Example 1, the difference is that the selenization steps of the pretreated MnCo-MOF material are as follows:

[0062] The pretreated MnCo-MOF material and selenium powder were placed in a tubular furnace with selenium powder upstream and MnCo-MOF material downstream. Under an argon atmosphere, the temperature was raised to 420°C at a rate of 5°C / min and kept warm for 2 hours. During this process, the argon flow rate was 35 sccm. Then the temperature was continued to be raised to 580°C and kept warm for 0.5 hours. During this process, the argon flow rate was 50 sccm to obtain a MnSe2 / CoSe2 / C composite material.

[0063] Comparative Example 2

[0064] Compared with Example 1, the MnCo-MOF material was prepared according to the method in Example 1. When the MnCo-MOF material was pretreated, the soaking solution used was a glucose aqueous solution with a mass percentage concentration of 30%, and then the same selenization treatment as in Example 1 was directly performed with selenium powder.

[0065] Blank group:

[0066] Compared with Example 1, the MnCo-MOF material is not pretreated and is directly selenized. The selenization step is that the MnCo-MOF material and selenium powder are placed in a tubular furnace, with the selenium powder upstream and the MnCo-MOF material downstream. Under an argon atmosphere, the temperature is raised to 580°C at a rate of 5°C / min and continued to be kept warm for 2.5 hours. During the process, the argon gas flow rate is 50sccm to obtain a MnSe2 / CoSe2 / C composite material.

[0067] The scanning electron microscope images of the composite materials prepared by each comparison are as follows Figure 4 As shown, the electron micrographs of the products of Comparative Example 1 (a), Comparative Example 2 (b) and the blank group (c) show that in Comparative Example 1, only pretreatment was performed, and because the argon gas flow rate of the two-step selenization was adjusted during the selenization process, although the cubic structure was retained to a large extent, the carbon material was not well coated on its surface, but formed adhesion between the cubic particles. In Comparative Example 2, when no alkyl glycoside was added during the pretreatment, the prepared product was completely unable to maintain the cubic structure and other morphological structures were formed. In the blank group, the structure collapsed and the morphology was more messy. After detection and calculation, the purity of the composite materials prepared in Comparative Example 1, Comparative Example 2 and the blank group were 81.9%, 95.6% and 76.3%, respectively.

[0068] In long-term experiments, we also tried to adjust the molar ratio of Mn and Co in the MnCo-MOF material and found that the prepared MOF materials can basically be prepared into a cubic uniform structure, which can be used as a template for the subsequent preparation of composite materials. However, the molar ratio of Mn and Co will lead to the proportion of Mn-based selenide and Co-based selenide in the subsequently prepared MnSe2 / CoSe2 / C composite material, thereby affecting its lithium storage performance. We found that when other conditions remain unchanged, when the molar ratio of Mn and Co is 1.2~1.8:1, the prepared MnSe2 / CoSe2 / C composite material has the best lithium storage performance.

[0069] Example 2

[0070] A method for preparing a lithium-ion battery electrode material comprises the following steps:

[0071] (1) Synthesis of MnCo-MOF materials

[0072] Mn(CH3COO)2·4H2O and PVP-K30 were dissolved in a mixed solvent of anhydrous ethanol and deionized water to obtain solution A, and K3Co(CN)6 was dissolved in deionized water to obtain solution B. Solution A and solution B were mixed according to a Mn to Co molar ratio of 1.2:1, aged at room temperature for 26 hours, and the precipitate was collected by centrifugation, washed with ethanol and deionized water in sequence, and then dried to obtain MnCo-MOF. In the solution A, the mass ratio of Mn(CH3COO)2·4H2O and PVP-K30 was 0.44:3, the mass volume ratio of Mn(CH3COO)2·4H2O to the mixed solvent was 0.5:100, and the volume ratio of anhydrous ethanol to deionized water was 2:1. In the solution B, the mass volume ratio of K3Co(CN)6 to deionized water was 0.68:100, and the unit was g / mL;

[0073] (2) Preprocessing

[0074] The MnCo-MOF material was immersed in a mixed aqueous solution of glucose and alkyl glycoside, kept at 90°C for 0.5h, and then dried. The mass percentage concentration of glucose in the mixed aqueous solution was 20%, and the mass ratio of glucose to alkyl glycoside was 4:0.5;

[0075] (3) Selenization treatment

[0076] The pretreated MnCo-MOF material and selenium powder were placed in a tubular furnace with selenium powder upstream and MnCo-MOF material downstream. Under an argon atmosphere, the temperature was raised to 450°C at a rate of 3°C / min and kept warm for 1.5 hours. During this process, the argon flow rate was 60 sccm. Then the temperature was continued to be raised to 550°C and kept warm for 1 hour. During this process, the argon flow rate was 40 sccm to obtain a MnSe2 / CoSe2 / C composite material.

[0077] The MnSe2 / CoSe2 / C composite material prepared in this example has a uniform cubic structure, uniform size, and high purity. The purity of the MnSe2 / CoSe2 / C composite material is calculated to be 99.1%. When the material is used as an electrode material for an ion battery, the -1 After 200 charge and discharge cycles at a current density of 1.5 GHz, the discharge capacity still reached 647 mAh g -1 As a new energy vehicle, lithium-ion batteries have excellent lithium storage performance and charge and discharge cycle stability.

[0078] Example 3

[0079] A method for preparing a lithium-ion battery electrode material comprises the following steps:

[0080] (1) Synthesis of MnCo-MOF materials

[0081] Mn(CH3COO)2·4H2O and PVP-K30 were dissolved in a mixed solvent consisting of anhydrous ethanol and deionized water to obtain solution A, and K3Co(CN)6 was dissolved in deionized water to obtain solution B. Solution A and solution B were mixed according to a Mn to Co molar ratio of 1.8:1, aged at room temperature for 15 hours, and the precipitate was collected by centrifugation, washed with ethanol and deionized water in sequence, and then dried to obtain MnCo-MOF. In the solution A, the mass ratio of Mn(CH3COO)2·4H2O and PVP-K30 was 0.22:0.75, the mass volume ratio of Mn(CH3COO)2·4H2O to the mixed solvent was 0.1:100, and the volume ratio of anhydrous ethanol to deionized water was 2:1. In the solution B, the mass volume ratio of K3Co(CN)6 to deionized water was 0.13:100, and the unit was g / mL;

[0082] (2) Preprocessing

[0083] The MnCo-MOF material was immersed in a mixed aqueous solution of glucose and alkyl glycoside, kept at 70°C for 1 hour, and then dried. The mass percentage concentration of glucose in the mixed aqueous solution was 40%, and the mass ratio of glucose to alkyl glycoside was 4:1;

[0084] (3) Selenization treatment

[0085] The pretreated MnCo-MOF material and selenium powder were placed in a tubular furnace with selenium powder upstream and MnCo-MOF material downstream. Under an argon atmosphere, the temperature was raised to 450°C at a rate of 2°C / min and kept warm for 2.5 hours. During this process, the argon flow rate was 45 sccm. Then the temperature was continued to be raised to 600°C and kept warm for 0.5~1 hour. During this process, the argon flow rate was 30 sccm to obtain a MnSe2 / CoSe2 / C composite material.

[0086] The MnSe2 / CoSe2 / C composite material prepared in this example has a uniform cubic structure, uniform size, and high purity. The purity of the MnSe2 / CoSe2 / C composite material is calculated to be 99.2%. When the material is used as an electrode material for lithium-ion batteries, the -1 After 200 charge and discharge cycles at a current density of 1.5 GHz, the discharge capacity still reached 637 mAh g -1 As a new energy vehicle, lithium-ion batteries have excellent lithium storage performance and charge and discharge cycle stability.

Claims

1. A method for preparing a lithium-ion battery electrode material, characterized in that: The steps include: (1) Synthesis of MnCo-MOF materials Mn(CH3COO)2·4H2O and PVP-K30 were dissolved in a mixed solvent consisting of anhydrous ethanol and deionized water to obtain solution A, and K3Co(CN)6 was dissolved in deionized water to obtain solution B. Solution A and solution B were mixed according to a molar ratio of Mn to Co of 1.2 to 1.8:1, aged at room temperature for 15 to 26 hours, and the precipitate was collected by centrifugation, washed with ethanol and deionized water in sequence, and then dried to obtain MnCo-MOF. In the solution A, The mass ratio of Mn(CH3COO)2·4H2O and PVP-K30 is 0.22~0.44:0.75~3, the mass volume ratio of Mn(CH3COO)2·4H2O and the mixed solvent is 0.1~0.5:100, the unit is g / mL, the volume ratio of anhydrous ethanol and deionized water is 2:1, and in the solution B, the mass volume ratio of K3Co(CN)6 and deionized water is 0.13~0.68:100, the unit is g / mL; (2) Preprocessing The MnCo-MOF material was immersed in a mixed aqueous solution of glucose and alkyl glycoside, kept at 70-90°C for 0.5-1h, and then dried, wherein the mass percentage concentration of glucose in the mixed aqueous solution was 20-40%, and the mass ratio of glucose to alkyl glycoside was 4:0.5-1; (3) Selenization treatment The pretreated MnCo-MOF material and selenium powder were placed in a tubular furnace with the selenium powder upstream and the MnCo-MOF material downstream. Under an argon atmosphere, the temperature was raised to 400-450°C at a rate of 2-5°C / min and kept warm for 1-1.5 hours. During this process, the argon flow rate was 45-60 sccm. Then the temperature was continued to be raised to 550-600°C and kept warm for 1-2.5 hours. During this process, the argon flow rate was 30-40 sccm to obtain a MnSe2 / CoSe2 / C composite material.

2. The lithium-ion battery electrode material prepared by the method for preparing a lithium-ion battery electrode material according to claim 1, wherein: The electrode material is a cubic MnSe2 / CoSe2 / C composite material, in which a carbon material is coated on the surface of the bimetallic selenide MnSe2 / CoSe2. The MnSe2 / CoSe2 / C composite material is obtained by using MnCo-MOF material as a precursor and then undergoing selenization treatment after pretreatment.

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