Novel battery electrode material and preparation method and application thereof

Abstract

The invention discloses a novel battery electrode material as well as a preparation method and application thereof. A metal organic framework (MOF) material generated by a solvothermal reaction of a manganese salt and 2, 5-dyhydroxy terephthalic acid is used for a lithium ion battery negative electrode, the battery material provided by the invention has rich redox centers and can store a large amount of lithium ions, in addition, the unique nano structure can rapidly conduct the lithium ions, the volume effect is effectively relieved, and the lithium ion battery negative electrode material can be applied to the lithium ion battery negative electrode. The material has the advantages of high specific capacity, good cycling stability and the like.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion batteries, and in particular relates to a novel battery electrode material, its preparation method, and its application. Background Technology

[0002] With the rapid development of portable consumer electronics and electric vehicles, lithium-ion batteries have gradually come into view. Their advantages, such as high energy density, no memory effect, high operating voltage, and low self-discharge, have quickly made them the mainstream commercial product. However, the negative electrode material of commercial lithium-ion batteries is graphite, whose low theoretical capacity (372 mAh / g) cannot meet market demand. Therefore, developing new negative electrode materials to replace graphite is key to improving the overall performance of lithium-ion batteries. Metal-organic frameworks (MOFs) have attracted much attention from researchers due to their large specific surface area, abundant porosity, and tunable structure. MOF materials are porous crystalline materials formed by the self-assembly and assembly of metal ions and organic ligands, and have been widely used in electrochemical energy storage, electrocatalysis, drug delivery, and adsorption separation.

[0003] In the research field of MOF materials applied to lithium-ion battery anode materials, literature CN112054186A discloses an Al-MOF anode material and literature CN118063786A discloses a Cu-MOF anode material; however, the specific capacity of the above materials is low, ranging from 200 to 300 mAh / g, and the cycle life is short, especially when cycling under high current, the cycle life is even shorter.

[0004] To further improve specific capacity, some studies have employed more complex processes, using MOF materials as precursors, calcining them to decompose them into other compounds, which are then used as anodes, as illustrated in literature CN 116646490 A. The problem with this process is the need for calcination, which requires an inert atmosphere. The control of calcination time and temperature increases production costs. If the process also involves compounding with other materials, it further reduces yield and productivity.

[0005] On the other hand, in the research of lithium-ion battery anode materials, the electrode materials often undergo significant volume changes due to the repeated insertion and extraction of lithium ions during long-term cycling, leading to structural pulverization and performance degradation, thereby limiting the cycle life of the battery. Summary of the Invention

[0006] The purpose of this invention is to provide a MOF material and its application in the negative electrode of a lithium-ion battery, so as to expand the application possibilities of MOF materials in the field of lithium-ion batteries.

[0007] This invention, from the perspective of nanostructure construction, improves the specific capacity and cycle life of MOF materials used as a negative electrode by selecting appropriate organic ligands and metal ions. At the same time, the organic ligands and metal ions can easily combine to self-assemble and generate the target product, which is convenient for preparation.

[0008] The target product designed in this invention has a unique structure that not only provides abundant active sites and diffusion channels for the storage and transport of lithium ions, but also effectively adapts to volume fluctuations during the charging and discharging process and maintains structural integrity.

[0009] This invention prepares high-performance metal-organic framework (MOF) anode materials by rationally selecting metal centers and organic ligands and constructing nanostructures with synergistic structural and component characteristics using self-assembly technology.

[0010] Specifically, this invention selects manganese as the metal center and 2,5-dihydroxyterephthalic acid (2,5-dihydroxyterephthalic acid) as the ligand, mainly because Mn ions have good redox activity, and oxygen-rich 2,5-dihydroxyterephthalic acid has many lithiation sites. Combining these two elements to self-assemble into a Mn-MOF nanostructure, used as a lithium-ion battery anode material, exhibits excellent electrochemical performance. Its abundant redox activity gives this MOF material a high specific capacity. Its unique porous nanostructure enables rapid lithium ion conduction, effectively mitigating volume expansion, resulting in good cycle performance.

[0011] Technical solution

[0012] This invention utilizes a metal-organic framework (MOF) material generated by a solvothermal reaction of manganese salt and 2,5-dihydroxyterephthalic acid for use as the negative electrode of a lithium-ion battery. The battery material provided by this invention has abundant redox centers, enabling it to store a large number of lithium ions. In addition, its unique nanostructure can rapidly conduct lithium ions, effectively mitigating the volume effect, and has advantages such as high specific capacity and good cycle stability.

[0013] A novel battery electrode material preparation method involves using a manganese-based MOF material generated by a solvothermal reaction of manganese salt and 2,5-dihydroxyterephthalic acid, and using the manganese-based MOF material as a negative electrode material for lithium-ion batteries.

[0014] Preferably, the preparation method of the lithium battery anode material specifically includes the following steps:

[0015] Step 1: First, add N,N-dimethylformamide, deionized water and anhydrous ethanol to the liner of the reaction vessel and mix well; then, add 2,5-dihydroxyterephthalic acid and manganese salt to the liner of the reaction vessel, and stir to fully dissolve the reactants to obtain a stable solution.

[0016] Step 2: Transfer the obtained stable solution to the reaction vessel, seal it, and place it in an oven for solvothermal reaction. After the reaction is complete, remove the reaction vessel and allow it to cool to room temperature. Collect the product by vacuum filtration and wash it twice with N,N-dimethylformamide, deionized water and anhydrous ethanol in sequence to obtain a brownish-yellow sample.

[0017] Step 3: Transfer the obtained brownish-yellow sample to an oven and vacuum dry it to obtain manganese-based MOF material;

[0018] Step 4: The manganese-based MOF material obtained in Step 3 is directly used as a negative electrode material for lithium batteries.

[0019] Furthermore, manganese salts can be selected from manganese chloride, manganese nitrate, and manganese acetate.

[0020] Furthermore, the ratio of N,N-dimethylformamide, deionized water, and anhydrous ethanol added to the reactor is 15:1:1.

[0021] Furthermore, the molar ratio of 2,5-dihydroxyterephthalic acid to manganese salt is 1:2 to 1:4.

[0022] Furthermore, the solvothermal reaction temperature is 100℃-150℃, and the reaction time is 12h-30h.

[0023] Furthermore, the vacuum drying temperature is 100℃-130℃, and the drying time is 12h-30h.

[0024] The metal-organic framework (MOF) material provided by this invention exhibits good redox activity of Mn ions and numerous 2,5-dihydroxyterephthalic acid lithiation sites during self-assembly, enabling it to store a large number of lithium ions. Its abundant redox activity gives it a high specific capacity. Furthermore, its unique porous nanostructure can rapidly conduct lithium ions, effectively alleviating volume expansion and giving the MOF material good cycling performance.

[0025] The present invention also provides a novel battery electrode material obtained by the preparation method described above.

[0026] The present invention also provides the application of the novel battery electrode material to improve the specific capacity and cycle performance of lithium-ion batteries, including the following steps: coating a slurry containing the lithium-ion battery negative electrode material onto a copper foil current collector, and drying it to obtain a lithium-ion battery negative electrode.

[0027] Beneficial effects

[0028] The MOF material provided by this invention has a simple synthesis method and a novel structure. When used as a negative electrode in lithium-ion batteries, it exhibits excellent electrochemical stability. The ligand used is 2,5-dihydroxyterephthalic acid, which coordinates with manganese ions to form a Mn-MOF structure with rich redox activity, resulting in high specific capacity.

[0029] The MOF material provided by this invention has a unique porous nanostructure that can rapidly conduct lithium ions, effectively alleviating volume expansion and giving the MOF material excellent cycling performance.

[0030] In summary, the preferred metal center, organic ligand, and preparation process of this invention simultaneously achieve the following three effects: a) increased specific capacity of MOF materials used as a negative electrode; b) increased cycle life of MOF materials used as a negative electrode under high current; c) easy binding of organic ligands and metal ions for convenient preparation. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 The XRD patterns of the products obtained in Examples 1, 2, and 3 are shown.

[0033] Figure 2 SEM images of (a) layered morphology L1(CI)-MnDHTP, (b) layered morphology L2(NO3)-MnDHTP and (c) spherical S(Ac)-MnDHTP.

[0034] Figure 3 For Examples 1, 2, and 3, the products obtained at (a) 100 mAg -1 and (b)2Ag -1 Battery performance test graph at current density. Detailed Implementation

[0035] 1. Various exemplary embodiments of the present invention are now described in detail. This detailed description should not be considered as a limitation of the invention, but rather as a more detailed description of certain aspects, features, and embodiments of the invention. Furthermore, with respect to numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0036] 2. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention.

[0037] 3. Various improvements and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, which will be apparent to those skilled in the art. Other embodiments derived from this specification will be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0038] 4. All raw materials in the embodiments of the present invention were obtained by purchase.

[0039] 5. In the embodiments of the present invention, MOF powder synthesized by solvothermal method was used as a negative electrode material and exhibited good electrochemical performance.

[0040] 6. The MOF material was prepared by solvent method. The structure of the MOF material provided by the present invention was characterized, as detailed in Examples (1)(2)(3).

[0041] Example 1

[0042] N,N-Dimethylformamide (DMF, 45 ml), deionized water (3 ml), and anhydrous ethanol (3 ml) were added to a 100 ml reaction vessel liner in a ratio of 15:1:1 (v / v / v) and mixed thoroughly. Then, 2,5-dihydroxyterephthalic acid (0.333 g) and MnCl2·4H2O (1.098 g) were added to the Teflon reaction vessel liner and dissolved completely under magnetic stirring. After obtaining a stable solution, the solution was transferred to the reaction vessel, sealed, and placed in an oven at 135°C for 24 h. After the reaction was completed, the reaction vessel was removed and cooled to room temperature. The product was collected by vacuum filtration and washed twice with N,N-dimethylformamide (DMF), deionized water, and anhydrous ethanol in sequence to obtain a brownish-yellow sample. Finally, the filtered sample was transferred to an oven and dried under vacuum at 110°C for 24 hours to obtain the final L1(CI)-MnDHTP product with a layered morphology.

[0043] Example 2

[0044] N,N-Dimethylformamide (DMF, 45 ml), deionized water (3 ml), and anhydrous ethanol (3 ml) were added to a 100 ml reaction vessel liner in a ratio of 15:1:1 (v / v / v) and mixed thoroughly. Then, 2,5-dihydroxyterephthalic acid (0.333 g) and Mn(NO3)2·4H2O (1.393 g) were added to the Teflon reaction vessel liner and dissolved completely under magnetic stirring. After obtaining a stable solution, the solution was transferred to the reaction vessel, sealed, and placed in an oven at 135°C for 24 h. After the reaction was completed, the reaction vessel was removed and cooled to room temperature. The product was collected by vacuum filtration and washed twice with N,N-dimethylformamide (DMF), deionized water, and anhydrous ethanol in sequence to obtain a brownish-yellow sample. Finally, the filtered sample was transferred to an oven and dried under vacuum at 110°C for 24 hours to obtain the final L2(NO3)-MnDHTP product with a layered morphology.

[0045] Example 3

[0046] N,N-Dimethylformamide (DMF, 45 ml), deionized water (3 ml), and anhydrous ethanol (3 ml) were added to a 100 ml reaction vessel liner in a ratio of 15:1:1 (v / v / v) and mixed thoroughly. Then, 2,5-dihydroxyterephthalic acid (0.333 g) and Mn(CH3COOH)2·4H2O (1.360 g) were added to the Teflon reaction vessel liner and thoroughly dissolved under magnetic stirring. After obtaining a stable solution, the solution was transferred to the reaction vessel, sealed, and placed in an oven at 135°C for 24 h. After the reaction was completed, the reaction vessel was removed and cooled to room temperature. The product was collected by vacuum filtration and washed twice with N,N-dimethylformamide (DMF), deionized water, and anhydrous ethanol in sequence to obtain a brownish-yellow sample. Finally, the filtered sample was transferred to an oven and dried under vacuum at 110°C for 24 hours to obtain the final spherical S(Ac)-MnDHTP product.

[0047] Sample Analysis

[0048] The crystal structures of L1(Cl)-MnDHTP, L2(NO3)-MnDHTP, and S(Ac)-MnDHTP were investigated using powder X-ray diffraction (PXRD), and the results showed that all three exhibit crystallinity. The PXRD patterns of these three MnDHTP samples were almost identical, and they were isomorphic to the rhombohedral Mn2(dhtp) (H4dhtp = 2,5-dihydroxyterephthalic acid) MOF, such as... Figure 1 As shown.

[0049] The microstructure of the prepared samples was characterized using scanning electron microscopy (SEM). It was clearly observed that when manganese chloride (MnCl2) was used as the manganese source, the prepared samples exhibited densely packed layered crystals (L1(Cl)-MnDHTP), with pores between the layers, and the layer thickness was 100-300 nm. Figure 2 (a) In contrast, when manganese nitrate (Mn(NO3)2) is used as the manganese source, the product (L2(NO3)-MnDHT) exhibits a similar morphology and size, but displays a more pronounced two-dimensional layered structure with irregular layer wall morphology. Figure 2 In stark contrast, the product (S(As)-MnDHTP) synthesized using manganese acetate (Mn(CH3COO)2, abbreviated as MnAc2) as the manganese source is composed of randomly interconnected porous microspheres with diameters ranging from 1 to 2 micrometers. These microspheres have rough surfaces and are formed by the aggregation of nanoparticles. Figure 2 (c)

[0050] Application examples

[0051] The electrochemical performance of MnDHTP MOFs as anode materials was tested using a CR2032 coin cell. The working electrode was prepared using a slurry coating method: active material, Super-P (conductive additive), and sodium carboxymethyl cellulose (binder) were mixed at a weight ratio of 70:20:10, and deionized water was added. The mixture was stirred at room temperature for 5 hours to obtain a uniform slurry. The slurry was uniformly coated onto a copper foil current collector and then dried under vacuum at 110℃ for 12 hours. The active material loading was controlled at 1.0-1.5 mg / cm³. 2 All specific capacities were calculated based on the masses of L1(Cl)-MnDHTP, L2(NO3)-MnDHTP, and S(Ac)-MnDHTP.

[0052] Button half-cells (CR2032) were assembled in an argon-filled glove box (H2O, O2 content <0.5ppm) and tested at 25°C. The electrolyte was a solution of 1M LiPF6 dissolved in EC / DMC / EMC (volume ratio 1:1:1) with the addition of 5% volumetric fluoroethylene carbonate (FEC). Lithium metal sheets were used as the counter / reference electrode, and a Celgard 2325 membrane was used as the separator. Constant current charge-discharge tests were conducted from 0.01 to 3.0 V (vs. Li / Li). + The test was performed within the specified voltage range using the LAND CT2001A battery testing system (Wuhan Jinno Electronics Co., Ltd.).

[0053] All samples were first tested at 100 mAg. -1 Cyclic performance tests were conducted at current densities. For example... Figure 3 As shown in Figure a, the three anode materials, L1(Cl)-MnDHTP, L2(NO3)-MnDHTP, and S(Ac)-MnDHTP, exhibited 600, 583, and 726 mAh g⁻¹, respectively, after more than 110 cycles. -1 It exhibits excellent reversible capacity and a coulombic efficiency approaching 100%. Subsequently, in 2Ag... -1 The MnDHTP electrode under high current density was subjected to long-cycle performance testing, such as... Figure 3 As shown in b, MnDHTP exhibits excellent high-rate cycling durability and stability, especially the layered structures L1(Cl)-MnDHTP and L2(NO3)-MnDHTP, in 2Ag... -1 After undergoing 1000 charge-discharge cycles at high current density, it still maintains 356 and 394 mAh g, respectively. -1 The reversible capacity indicates that it has ultra-stable cycling characteristics and excellent high-rate performance.

[0054] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a novel battery electrode material, characterized in that, Manganese-based MOF materials are generated by a solvothermal reaction of manganese salts with 2,5-dihydroxyterephthalic acid, and these manganese-based MOF materials are used as anode materials for lithium-ion batteries.

2. The preparation method according to claim 1, characterized in that, Specifically, the following steps are included: Step 1: First, add N,N-dimethylformamide, deionized water and anhydrous ethanol to the liner of the reaction vessel and mix well; then, add 2,5-dihydroxyterephthalic acid and manganese salt to the liner of the reaction vessel, and stir to fully dissolve the reactants to obtain a stable solution. Step 2: Transfer the obtained stable solution to the reaction vessel, seal it, and place it in an oven for solvothermal reaction. After the reaction is complete, remove the reaction vessel and allow it to cool to room temperature. Collect the product by vacuum filtration and wash it twice with N,N-dimethylformamide, deionized water and anhydrous ethanol in sequence to obtain a brownish-yellow sample. Step 3: Transfer the obtained brownish-yellow sample to an oven and vacuum dry it to obtain manganese-based MOF material; Step 4: The manganese-based MOF material obtained in Step 3 is directly used as a negative electrode material for lithium batteries.

3. The preparation method according to claim 1, characterized in that: The manganese salt in step 1 is any one of manganese chloride, manganese nitrate, and manganese acetate.

4. The preparation method according to claim 1, characterized in that: The molar ratio of 2,5-dihydroxyterephthalic acid to manganese salt ranges from 1:2 to 1:

4.

5. The preparation method according to claim 1, characterized in that: In step 1, the volume ratio of N,N-dimethylformamide, deionized water, and anhydrous ethanol is 15:1:

1.

6. The preparation method according to claim 1, characterized in that: In step 2, the solvothermal reaction temperature is 100℃-150℃, and the reaction time is 12h-30h.

7. The preparation method according to claim 1, characterized in that: In step 3, the vacuum drying temperature is 100℃-130℃, and the drying time is 12h-30h.

8. A novel battery electrode material obtained by the preparation method according to any one of claims 1 to 7.

9. The application of the novel battery electrode material according to claim 8, characterized in that, The method is applied to improve the specific capacity and cycle performance of lithium-ion batteries, and includes the following steps: coating a slurry containing the lithium-ion battery negative electrode material onto a copper foil current collector, and drying it to obtain a lithium-ion battery negative electrode.

10. The application of the novel battery electrode material according to claim 9, characterized in that, The cycle is at 100mAg -1 or 2Ag -1 The lithium-ion battery anode material is subjected to charge-discharge cycles at a current density of 1.0-1.5 mg / cm³. 2 .

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