A method for preparing and applying 2,5-dibromoterephthalate diethyl ester composite TiO2·H2O

Abstract

The application provides a preparation method and application of 2,5-dibromoparabenzene diethyl ester composite TiO2.H2O, and the preparation method comprises the following steps: (1) placing 2,5-dibromoparabenzene diethyl ester into a beaker containing 40ml of anhydrous ethanol; (2) placing the beaker in step (1) on a magnetic stirrer to start stirring at room temperature; (3) measuring 0.34ml of tetrabutyl titanate and adding the tetrabutyl titanate into the beaker; (4) stopping stirring after stirring for 30min, heating the solution in the beaker to 160-200 DEG C through stirring, cooling to room temperature after keeping the temperature for 24h, forming white crystals, collecting the crystals through suction filtration, washing the crystals with anhydrous ethanol for 2-3 times, and drying the crystals in a blast drying oven at 60 DEG C to obtain a DT sample; and applying the prepared DT to a lithium battery. The DT material is prepared through the method, and non-toxic chemicals are used in the preparation process.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, and particularly relates to a method for preparing and applying a 2,5-dibromoterephthalate diethyl ester composite TiO2·H2O. Background Technology

[0002] Lithium-ion batteries are widely used in portable electronic products. Common lithium-ion anode materials, such as carbon anode materials, lithium titanate anode materials (low capacity), and silicon anode materials (poor cycle stability), cannot meet the requirements. Therefore, the design and development of electrode materials with high power density and energy density are of great significance for the practical application of batteries.

[0003] Organic electrode materials, as an emerging class of materials, are attracting increasing research interest in the field of rechargeable batteries due to their abundance, high theoretical capacity, and vast functional design potential. Liu et al. proposed placing 4.8 g of 2,5-dibromoterephthalic acid in 50 mL of anhydrous ethanol and 2 mL of concentrated sulfuric acid, then heating the mixture and refluxing for 24 hours. The solvent was removed under reduced pressure, and the mixture was purified by column washing with n-hexane and ethyl acetate to obtain diethyl 2,5-dibromoterephthalate as a white solid. The concentrated sulfuric acid used in the existing preparation of diethyl 2,5-dibromoterephthalate is a hazardous chemical, and the synthesized substance does not contain TiO2·H2O. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of using concentrated sulfuric acid, a hazardous chemical, in the preparation of diethyl 2,5-dibromoterephthalate and the absence of TiO2·H2O in the synthesized substances.

[0005] To achieve the above objectives, this invention provides a method for preparing and applying diethyl 2,5-dibromoterephthalate composite TiO2·H2O, comprising the following steps:

[0006] (1) Pour 40 ml of anhydrous ethanol into a beaker, and then put 1.2957 g of 2,5-dibromo-2-benzoic acid into the beaker containing anhydrous ethanol.

[0007] (2) Place the beaker from step (1) onto a magnetic stirrer and stir at room temperature;

[0008] (3) While stirring, add 0.34 ml of tetrabutyl titanate to the beaker using a pipette;

[0009] (4) Stop stirring after 30 minutes, pour the solution in the beaker into the tetrafluoroethylene liner, then put the tetrafluoroethylene liner into the hydrothermal reactor, seal the hydrothermal reactor and put it into the oil bath to stir and heat to 160-200℃, keep it at the temperature for 24 hours and then cool it to room temperature to form white crystals. Collect the crystals by vacuum filtration, wash and dry them to obtain 2,5-dibromoterephthalic acid diethyl ester composite TiO2·H2O at different temperatures.

[0010] Furthermore, the washing in step (4) is performed by washing 2-3 times with anhydrous ethanol, and the drying is carried out in a forced-air drying oven at 60°C.

[0011] A method for manufacturing lithium-ion batteries using a 2,5-dibromoterephthalate diethyl ester composite TiO2·H2O, characterized by comprising the following steps:

[0012] S1. After uniformly mixing 2,5-dibromoterephthalate diethyl ester composite TiO2·H2O, conductive carbon black KS-6, conductive carbon black Super P, and binder in a mass ratio of 6:2:1:1, the mixed slurry is coated onto carbon copper foil. The coated electrode material is then dried, and the dried electrode material is made into a disc with a diameter of 12 mm to obtain an electrode sheet.

[0013] S2. Place the cut electrode sheets, Celgard2500 separator, lithium metal sheet, gasket, spring, positive electrode shell, negative electrode shell, and electrolyte into a glove box filled with argon gas. Assemble the electrode sheets, Celgard2500 separator, lithium metal sheet, gasket, spring, positive electrode shell, and negative electrode shell in a certain order, and then place them on a sealing machine to press and seal them to obtain a button battery.

[0014] Furthermore, the drying in step S1 is performed by drying in a vacuum chamber at 100°C for 12 hours.

[0015] Furthermore, in step S2, the Celgard 2500 separator has a diameter of 16 mm, the lithium metal sheet has a diameter of 15 mm, the coin cell casing is CR2032, the electrolyte is 1M LiPF6, and the mass ratio of the solvent is EC:DEC:EMC of 1:1:1.

[0016] Furthermore, in step S2, the H2O and O2 concentrations in the argon glove box are less than 1 ppm.

[0017] Beneficial effects:

[0018] 1. The prepared DT material exhibits higher discharge specific capacity, extending battery life. Batteries using DT materials can provide longer driving range for mobile devices, electric vehicles, and other applications.

[0019] 2. In existing technologies, diethyl 2,5-dibromoterephthalate is prepared using concentrated sulfuric acid, which is a hazardous chemical and poses certain risks during the experiment. In this invention, tetrabutyl titanate is used instead of concentrated sulfuric acid to prepare diethyl 2,5-dibromoterephthalate composite TiO2·H2O, reducing the risks of the experiment. Furthermore, no existing technology uses diethyl 2,5-dibromoterephthalate composite TiO2·H2O as a lithium-ion battery material. Attached Figure Description

[0020] Figure 1 This is a flowchart of the preparation process of DT material provided by the present invention;

[0021] Figure 2 This is a discharge cycle diagram of the DT-180 sample provided by the present invention;

[0022] Figure 3 This is a diagram showing the assembly sequence of a button battery provided by the present invention;

[0023] Figure 4 These are XRD patterns of DT samples prepared at different temperatures according to the present invention;

[0024] Figure 5 This is a diagram of diethyl 2,5-dibromo-terephthalate provided by the present invention;

[0025] Figure 6 These are the calculated XRD patterns of DT material and the experimental XRD patterns of DT-180 provided by this invention;

[0026] Figure 7(A) is the XPS full spectrum of the DT-180 sample provided by the present invention;

[0027] Figure 7(B) is the C1s plot of the DT-180 sample provided by the present invention;

[0028] Figure 7(C) is the O1s diagram of the DT-180 sample provided by the present invention;

[0029] Figure 7(D) is the Br3d diagram of the DT-180 sample provided by the present invention;

[0030] Figure 7(E) is the Ti2p diagram of the DT-180 sample provided by the present invention;

[0031] Figure 8 This is a reaction mechanism diagram provided by the present invention.

[0032] Note: DT: Diethyl 2,5-dibromoterephthalate composite TiO2·H2O, binder: polyvinylidene fluoride (PVDF, 0.15g) dispersed in N-methylpyrrolidone (NMP, 30ml), EC: ethylene carbonate, EMC: ethyl methyl carbonate, PC: propylene carbonate. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0034] The application principle of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1:

[0036] like Figure 1 As shown, a method for preparing a diethyl 2,5-dibromoterephthalate composite TiO2·H2O includes the following steps:

[0037] (1) Measure 40 ml of anhydrous ethanol into a beaker using a graduated cylinder, and weigh 1.2957 g of 2,5-dibromo-p-benzoic acid into the beaker containing anhydrous ethanol.

[0038] (2) Place the beaker from step (1) on a magnetic stirrer and start stirring at room temperature.

[0039] (3) While stirring, add 0.34 ml of tetrabutyl titanate to the beaker using a pipette.

[0040] (4) After stirring for 30 minutes, stop stirring and pour the solution in the beaker into a 100 ml polytetrafluoroethylene liner. Place the polytetrafluoroethylene liner in the hydrothermal reactor, seal the hydrothermal reactor, and then place the hydrothermal reactor in an oil bath and heat it to 180°C. After holding the temperature for 24 hours, cool it to room temperature to form white crystals. Collect the crystals by vacuum filtration, wash them 2-3 times with anhydrous ethanol, and dry them in a 60°C forced-air drying oven to obtain 0.9519 g of DT-180 sample, with a yield of 62.62%.

[0041] (5) Perform XRD tests on the DT-180 sample obtained in step (4).

[0042] Lithium-ion batteries were fabricated using DT-180 samples:

[0043] (1) Electrode sheets were prepared using DT-180 sample. The preparation of electrode sheets involved uniformly mixing DT-180 sample, conductive carbon black KS-6, conductive carbon black SuperP, and binder in a mass ratio of 6:2:1:1. The mixed slurry was then coated onto carbon copper foil. The coated electrode material was then placed in a vacuum drying oven and dried at 100°C for 12 hours. Finally, the dried electrode material was cut into circular pieces with a diameter of 12 mm using a slicer to obtain electrode sheets.

[0044] (2) Figure 2 As shown, the cut electrode sheets, Celgard2500 separator, lithium metal sheet, gasket, spring, positive electrode shell, coin cell shell, and electrolyte are placed in a glove box filled with argon (H2O, O2 < 1ppm). The electrode sheets, Celgard2500 separator, lithium metal sheet, gasket, spring, positive electrode shell, and coin cell shell are then assembled in a specific order and placed on a sealing machine to press and seal, thus obtaining a coin cell. The Celgard2500 separator has a diameter of 16mm, the lithium metal sheet has a diameter of 15mm, the coin cell shell is CR2032, and the electrolyte is 1M LiPF6 with a solvent mass ratio of EC:DEC:EMC equal to 1:1:1.

[0045] (3) Charge-discharge cycle tests were performed on the Blue Electricity testing system, and the test results are as follows: Figure 3 DT-180 samples at 0.01–3V and 100 mAg -1 Under these conditions, the specific capacity initially decreases and then increases during cycling. During the second discharge cycle, the capacity suddenly drops significantly, and this decrease continues throughout the subsequent nine charge-discharge cycles. The discharge capacity during the first discharge cycle is 1089.4 mAh g. -1 During the 9th discharge cycle, the capacity reached a minimum of 584.6 mAh g. -1 (This represents 53.66% of the discharge capacity of the first cycle and 88.59% of the discharge capacity of the second cycle), and the capacity reaches 671.4 mAh g after 100 discharge cycles. -1 (It represents 61.63% of the first discharge capacity and 101.74% of the second discharge capacity).

[0046] Example 2:

[0047] It has the same implementation content as Embodiment 1 described above. For specific implementation details of the above embodiments, please refer to the above description; the embodiments described here will not be repeated in detail. However, the difference between this embodiment and the above embodiments lies in:

[0048] In step (4) of a method for preparing diethyl 2,5-dibromoterephthalate composite TiO2·H2O, a hydrothermal reactor is placed in an oil bath and heated to 160-200℃ with stirring. After holding at this temperature for 24 hours, it is cooled to room temperature. White crystals are formed. The crystals are collected by vacuum filtration, washed 2-3 times with anhydrous ethanol, and dried in a forced-air drying oven at 60℃ to obtain DT samples at different temperatures.

[0049] like Figure 4It can be seen that DT samples prepared at different heat preservation temperatures all crystallize and the peak positions are consistent, indicating that the products generated at different heat preservation temperatures are the same. However, the peaks of the DT samples do not have corresponding standard cards in any XRD database. Therefore, it can be determined that DT-180 material is a new substance.

[0050] Since the synthesized DT-180 material is a novel material, there is no corresponding standard card in the XRD standard card library, making it impossible to determine its structure and composition. Therefore, this study resolved the material's structure by cultivating single crystals and performing single-crystal diffraction. The single-crystal diffraction results show that DT material is diethyl 2,5-dibromoterephthalate, and its crystal structure is as follows: Figure 5 The synthesized diethyl 2,5-dibromo-terephthalate monomer, such as... Figure 5 A in the middle is... Figure 5 B and Figure 5 As can be seen from C, benzene rings appear in the unit cell in a common herringbone stacking pattern. Figure 5 D in the diagram represents the pores of the crystal, indicating that the material has pores. Single-crystal diffraction analysis shows that the single crystal does not contain titanium, indicating that the single crystal does not contain titanium material. The titanium-containing material is in a mixed state with the unformed diethyl 2,5-dibromoterephthalate in the mother liquor.

[0051] The structure of the material obtained from single-crystal diffraction analysis was calculated using VESTA software to obtain its XRD pattern, which was then compared with the experimentally obtained XRD pattern. Based on... Figure 6 It can be seen that the peak positions of the XRD spectrum of DT-180 obtained in the experiment are consistent with those of the XRD spectrum calculated from the single crystal structure, indicating that the sample synthesized in the experiment is diethyl 2,5-dibromoterephthalate. Furthermore, no characteristic peaks of titanium-containing substances were found in the XRD of DT-180, indicating that the titanium-containing substance is either amorphous or present in very small amounts.

[0052] XPS analysis was performed on the DT-180 sample. Figure 7(A) shows the full XPS spectrum of the DT-180 sample, which contains C, O, Br, and Ti elements. Figure 7(B) shows the C1s spectrum of the DT-180 sample, where 284.80 eV, 285.81 eV, 289.04 eV, 292.95 eV, and 295.76 eV correspond to C / C=C, CO, C=O, C-Br bonds, and associated peaks, respectively. Figure 7(C) shows the O1s spectrum of the DT-180 sample, where 530.07 eV, 531.76 eV, and 533.27 eV correspond to Ti-O, C=O, and CO, respectively. Figure 7(D) shows the Br3d spectrum of the DT-180 sample. The Br3d peaks have overlapping spin orbital components, so there are two Br3d peaks, corresponding to C-Br peaks at 70.10 eV and 71.00 eV. Figure 7(E) shows the Ti2p spectrum of the DT-180 sample. At 458.70 eV and 464.38 eV, they correspond to Ti2p3 / 2 and Ti2p1 / 2, respectively. These correspond to the orbital electron binding energies of titanium dioxide reported in the literature. That is, the XPS test shows that the Ti element in the composite material exists in the form of TiO2.

[0053] Diethyl 2,5-dibromo-terephthalate was synthesized during the single-crystal structure experiment. XPS analysis revealed that the titanium-containing substance existed in the form of titanium dioxide, i.e., the reaction mechanism was as follows: Figure 8 The first step involves the esterification of 2,5-dibromoterephthalic acid and ethanol to produce diethyl 2,5-dibromoterephthalate and H₂O. This esterification reaction is reversible. The added tetrabutyl titanate reacts with the H₂O generated in the esterification reaction to produce TiO·(OH)₂ (TiO₂·H₂O) and C₄H₉OH. The added tetrabutyl titanate consumes the water in the esterification products, disrupting the equilibrium of the reversible esterification reaction and promoting its occurrence. After the solvothermal reaction, a large amount of diethyl 2,5-dibromoterephthalate, TiO₂·H₂O, and C₄H₉OH are generated. In this process, 2,5-dibromoterephthalic acid and tetrabutyl titanate are essentially consumed. C2H5OH, H2O, and C4H9OH were filtered (shown by the blue dashed box in the figure). The resulting solid was a composite material of diethyl 2,5-dibromoterephthalate and TiO·(OH)2.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing lithium-ion batteries using diethyl 2,5-dibromo-terephthalate composite TiO2·H2O, characterized in that, Includes the following steps: S1. By uniformly mixing 2,5-dibromoterephthalate diethyl ester composite TiO2·H2O, conductive carbon black KS-6, conductive carbon black SuperP, and binder in a mass ratio of 6:2:1:1, the mixed slurry is coated on carbon copper foil and dried to form a disc with a diameter of 12mm, thus obtaining an electrode sheet. The preparation method of 2,5-dibromoterephthalate diethyl ester composite TiO2·H2O includes the following: (1) Pour 40 ml of anhydrous ethanol into a beaker, and then put 1.2957 g of 2,5-dibromo-terebenzoic acid into the beaker containing anhydrous ethanol. (2) Place the beaker from step (1) onto a magnetic stirrer and stir at room temperature; (3) While stirring, add 0.34 ml of tetrabutyl titanate to the beaker using a pipette; (4) Stop stirring after 30 minutes, pour the solution in the beaker into the polytetrafluoroethylene liner, then put the polytetrafluoroethylene liner into the hydrothermal reactor, seal the hydrothermal reactor and put it into the oil bath and stir and heat to 160-200℃. After keeping it at the temperature for 24 hours, cool it to room temperature to form white crystals. Collect the crystals by vacuum filtration, wash and dry them to obtain 2,5-dibromoterephthalic acid diethyl ester composite TiO2·H2O at different reaction temperatures; S2. Place the cut electrode sheets, Celgard2500 separator, lithium metal sheet, gasket, spring, positive electrode shell, negative electrode shell, and electrolyte into a glove box filled with argon gas. Assemble the electrode sheets, Celgard2500 separator, lithium metal sheet, gasket, spring, positive electrode shell, and negative electrode shell in a certain order, and then place them on a sealing machine to press and seal them to obtain a button battery.

2. The method according to claim 1, characterized in that, The washing in step (4) is performed by washing 2-3 times with anhydrous ethanol, and the drying is carried out in a forced-air drying oven at 60°C.

3. The method according to claim 1, characterized in that, In step S1, drying is performed by drying in a vacuum chamber at 100°C for 12 hours.

4. The method according to claim 1, characterized in that, In step S2, the Celgard 2500 separator has a diameter of 16 mm, the lithium metal sheet has a diameter of 15 mm, the coin cell casing is CR2032, and the electrolyte is 1M LiPF6 and solvent, with the solvent being EC, DEC, and EMC in a mass ratio of 1:1:

1.

5. The method according to claim 1, characterized in that, In step S2, the H2O and O2 concentrations in the argon-filled glove box are less than 1 ppm.

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