Amide naphthoquinone organic electrode material, preparation method thereof and application of amide naphthoquinone organic electrode material in lithium ion battery

Abstract

The invention discloses an amide naphthoquinone organic electrode material, a preparation method thereof and application of the amide naphthoquinone organic electrode material in a lithium ion battery. According to the invention, the low-price naphthoquinone compound is used as a reaction raw material to synthesize the amide naphthoquinone organic electrode material, and the method has the advantages of low synthesis cost, simple method, easy purification, high yield, large-scale preparation and the like. The obtained amide naphthoquinone organic electrode material has extremely low solubility and excellent electrochemical performance due to the synergistic effect of intermolecular hydrogen bonds and pi-pi accumulation, shows relatively high specific capacity, excellent cycling stability and excellent rate capability in a lithium ion battery as a positive electrode material, and has good commercial value.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage materials, and particularly relates to a novel amide naphthoquinone-based organic electrode material, a preparation method thereof, and an application thereof in a lithium-ion battery. Background Art

[0002] Lithium-ion batteries are widely used in fields such as portable electronic products and electric vehicles. The commercially available cathode materials for lithium-ion batteries are mainly inorganic materials, such as LiCoO 2 , LiMn 2 O 4 , LiFePO 4 and so on. Due to their low energy density and limited natural resources, and the increasing prices of these metal resources, the development of lithium-ion batteries has encountered bottlenecks to a certain extent.

[0003] Organic electrode materials have advantages such as rich resources, environmental friendliness, and strong molecular designability, and have received increasing attention and developed very rapidly in recent years. Among them, the structure of the electrode material is the key factor determining the battery performance. Searching for and exploring low-cost and high-efficiency organic electrode materials is crucial for the practical application of future lithium-ion batteries.

[0004] Naphthoquinone has a stable two-electron oxidation-reduction process and a high specific capacity, and has received extensive attention in the design of organic electrode materials, with good application prospects and commercial value. However, the solubility of naphthoquinone small molecules in the electrolyte is relatively high, which will lead to poor cycling performance of organic batteries. Therefore, it is of great significance to design and synthesize organic small molecule materials with low solubility. The current dissolution inhibition strategies focus on increasing the conjugated system of molecules, and their preparation processes are complex and costly. In 2022, Fu et al. (Zhao, B.W.; Si, Y.B.; Guo, W.; Fu, Y.Z. Insoluble Naphthoquinone-Derived Molecular Cathode for High-Performance Lithium Organic Battery. Adv. Funct. Mater. 2022, 32(19), 7. DOI: 10.1002 / adfm.202112225.) reported a novel naphthoquinone-based material 1,4-PNQ, which greatly reduced its solubility through expanding the molecular skeleton and strong intermolecular π-π interactions. However, when 1,4-PNQ is used as the electrode material for a lithium-organic battery, at a current density of 1C and after 100 cycles, the capacity decays to 80% of the initial capacity, because relying solely on intermolecular π-π interactions is not sufficient to maintain the stability of the 1,4-PNQ electrode material during cycling. Summary of the Invention

[0005] The object of the present invention is to provide an amide naphthoquinone organic electrode material with extremely low solubility and good electrochemical stability, and to provide a high-efficiency preparation method for this material that is low-cost and easy to scale up.

[0006] The structural formula of the amide naphthoquinone organic electrode material provided by the present invention is shown as the following formula A or B:

[0007]

[0008] In the above structural formula, E represents a carbon or nitrogen atom; R represents hydrogen, nitro, cyano, fluorine, bromine, chlorine, C 1 ~C 4 alkyl, C 1 ~C 4 alkoxy, hydroxyl, amino, any one of them.

[0009] The preparation method of the above amide naphthoquinone organic electrode material is as follows: Add a naphthoquinone compound, a compound of formula I or formula II, and a base into an organic solvent, stir and react at 60 - 100 °C for 12 - 24 hours. After the reaction is completed, cool to room temperature, filter to collect the precipitate, wash it with a washing solvent, and dry it to obtain the amide naphthoquinone organic electrode material shown in formula A or B; the reaction equation is shown as follows:

[0010]

[0011] 1 wherein, R

[0012] in formula I or formula II represents a methyl group or a hydrogen atom.

[0013] In the above preparation method, it is preferred that the molar ratio of the amide functional group in the naphthoquinone compound and the compound of formula I or formula II is 1:1 - 2:1.

[0014] In the above preparation method, it is preferred that the base is any one of N,N - diisopropylethylamine, potassium carbonate, and triethylamine.

[0015] In the above preparation method, it is preferred that the organic solvent is any one of N,N - dimethylformamide and acetonitrile.

[0016] In the above preparation method, it is preferred that the washing solvent is N,N - dimethylformamide and ethanol.

[0017] The present invention also provides an application of the above amide naphthoquinone organic electrode material as a cathode material in a lithium-ion battery. The preparation process of the lithium-ion battery is as follows: Mix the amide naphthoquinone organic electrode material, a conductive additive, a binder, and a dispersion solvent and grind them to obtain a slurry; coat the slurry on a current collector, and obtain an electrode sheet after drying and slicing; use the electrode sheet as the cathode, a lithium metal sheet as the counter electrode, add an electrolyte, and assemble a lithium-ion battery in a glove box. The mass ratio of the amide naphthoquinone organic electrode material, the conductive agent, and the binder is 6:3:1, wherein the conductive agent is any one of Ketjen black, Super P, and carbon nanotubes, the binder is polyvinylidene fluoride (PVDF), the dispersion solvent is N-methylpyrrolidone, the electrolyte in the electrolyte is lithium bis(trifluoromethanesulfonyl)imide, and the solvent of the electrolyte is a mixed solvent of dimethoxyethane (DME) and 1,3-dioxolane (DOL) with a volume ratio of 1:1.

[0018] The beneficial effects of the present invention are as follows:

[0019] The present invention uses inexpensive naphthoquinone compounds as reaction raw materials to synthesize amide naphthoquinone organic electrode materials. The synthesis cost is low, the method is simple, the product is easy to purify, column chromatography separation is not required, and the yield is high, and it can be prepared on a large scale. Due to the synergistic effect of intermolecular hydrogen bonding and π-π stacking, the obtained amide naphthoquinone organic electrode material has extremely low solubility. At the same time, as a cathode material in a lithium-ion battery, it exhibits a high specific capacity, excellent cycle stability, and excellent rate performance, and has good commercial value. Description of the Drawings

[0020] Figure 1 is the 1H NMR spectrum of the compound NQ1 prepared in Example 1.

[0021] Figure 2 is the 1H NMR spectrum of the compound NQ2 prepared in Example 2.

[0022] Figure 3 is the cyclic voltammogram of the compound NQ1 in a lithium-ion battery (scan rate is 0.1 mV s -1 ).

[0023] Figure 4 is the cyclic voltammogram of the compound NQ2 in a lithium-ion battery (scan rate is 0.1 mV s -1 ).

[0024] Figure 5 is the charge-discharge curve of the compound NQ1 in a lithium-ion battery (current density is 0.1 A g -1 ).

[0025] Figure 6is the charge-discharge curve of compound NQ2 in a lithium-ion battery (current density is 0.1 Ag -1 ).

[0026] Figure 7 is the cycling performance graph of compounds NQ1 and NQ2 in a lithium-ion battery (current density is 2 Ag -1 ). Specific Embodiments

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to these embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.

[0028] Example 1

[0029]

[0030] Add 1,4-naphthoquinone (15.8 g, 100 mmol), S1 (5.6 g, 25 mmol), N,N-diisopropylethylamine (26 mL, 150 mmol) and N,N-dimethylformamide (250 mL) to a 500 mL round-bottom flask, stir and react at 70 °C for 16 hours. After the reaction is completed, cool to room temperature, filter and collect the precipitate, and wash it with N,N-dimethylformamide and ethanol. After drying at 80 °C, the pure product of compound NQ1 is obtained with a yield of 75%.

[0031] The structural characterization data of compound NQ1 are as follows: 1 H NMR (600 MHz, CDCl 3 / CF 3 COOD (9:1, v / v)): δ (ppm) = 9.46 (s, 2H), 8.27 (b, 2H), 8.23 (b, 2H), 8.14 (b, 4H), 8.11 (s, 2H), 7.92 - 7.85 (m, 4H); 13 C NMR (150 MHz, CDCl 3 / CF 3 COOD (9:1, v / v)): δ (ppm) = 188.43, 180.25, 167.11, 140.53, 136.68, 135.91, 134.88, 131.64, 129.71, 128.51, 127.57, 127.30, 117.80, see Figure 1 .

[0032] Example 2

[0033]

[0034] Add 1,4-naphthoquinone (15.8 g, 100 mmol), S2 (4.95 g, 16.7 mmol), N,N-diisopropylethylamine (26 mL, 150 mmol) and N,N-dimethylformamide (250 mL) to a 500 mL round-bottom flask. Stir the reaction at 70 °C for 16 hours. After the reaction is completed, cool it to room temperature, filter to collect the precipitate, and wash it with N,N-dimethylformamide and ethanol. After drying at 80 °C, obtain the pure compound NQ2 with a yield of 85%.

[0035] The structural characterization data of compound NQ2 are as follows: 1 H NMR (600 MHz, CDCl 3 / CF 3 COOD (9:1, v / v)): δ (ppm) = 9.60 (s, 3H), 8.81 (s, 3H), 8.22 - 8.18 (m, 6H), 8.12 (s, 3H), 7.92 - 7.85 (m, 6H); 13 C NMR (150 MHz, CDCl 3 / CF 3 COOD (9:1, v / v)): δ (ppm) = 188.96, 180.38, 166.40, 140.84, 135.96, 135.08, 134.59, 131.47, 131.39, 129.70, 127.61, 127.26, 118.38, see Figure 2 。

[0036] Example 3

[0037]

[0038] In this example, replace S1 in Example 1 with an equimolar amount of S3, and keep the other steps the same as in Example 1 to obtain compound NQ3 with a yield of 88%.

[0039] Example 4

[0040]

[0041] In this example, replace S2 in Example 2 with an equimolar amount of S4, and keep the other steps the same as in Example 2 to obtain compound NQ4 with a yield of 90%.

[0042] Example 5

[0043] Applications of compounds NQ1 and NQ2 as the cathode materials for lithium-ion batteries

[0044] Place 30 mg of compound NQ1 or NQ2, 15 mg of Ketjen black, and 5 mg of PVDF in a mortar. After grinding and mixing evenly, add 0.2 mL of N-methylpyrrolidone and continue grinding to make a uniform slurry. Coat the slurry evenly on an aluminum foil current collector with a film applicator and vacuum dry it at 80 °C for 12 hours. Punch the dried coated aluminum foil into circular pieces with a diameter of 12 mm (i.e., electrode sheets) using a battery punching machine. In a glove box, use the prepared electrode sheet as the positive electrode, a lithium metal sheet as the counter electrode, polypropylene as the battery separator, and the electrolyte as a 1.0 M solution of lithium bis(trifluoromethanesulfonyl)imide in DOL / DME (1:1, v / v). Sequentially place the electrode sheet, electrolyte, separator, lithium metal sheet, gasket, and spring piece into the battery positive electrode case, cover the battery negative electrode case, and encapsulate the battery with a battery sealer to make a CR 2032 type button lithium-ion battery. After standing for 8 hours, test its electrochemical performance, and the results are as Figures 3 to 7 shown.

[0045] As can be seen from Figure 3 and Figure 4 , compound NQ1 has two pairs of redox peaks at 2.4 V and 2.6 V respectively, and compound NQ2 has three pairs of broad redox peaks in the voltage range of 2.0 - 2.8 V, indicating that both compound NQ1 and NQ2 have good electrochemical activity.

[0046] It can be seen from Figure 5 and Figure 6 that both compound NQ1 and NQ2 have good charge-discharge platforms, and the average voltage of the discharge platform is about 2.5 V.

[0047] As can be seen from Figure 7 , after 1000 cycles, the capacities of compound NQ1 and NQ2 are maintained at 80 mAh g -1 and 120 mAh g -1 respectively, and the Coulombic efficiency of both during the cycling process is about 100%, showing good cycling performance.

[0048] The core of the electrode material of the present invention lies in its amide naphthoquinone parent skeleton. The unique molecular arrangement and electronic effect of this parent skeleton constitute the basis for achieving its technical effects of high specific capacity, excellent cycle stability, and excellent rate performance. The specific selection of the R substituent is mainly used to adjust the physical and chemical properties of the compound (such as solubility, stability, etc.), and does not have a substantial impact on the core performance; the R substitution in the above examples can be replaced with any one of nitro, cyano, fluorine, bromine, chlorine, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, hydroxyl, or amino, and similar electrochemical performance can also be obtained.

Claims

1. An amide naphthoquinone organic electrode material, characterized in that: The structural formula of the material is shown in the following formula A or B: In the above structural formula, E represents a carbon or nitrogen atom; R represents any one of hydrogen, nitro, cyano, fluorine, bromine, chlorine, C1-C4 alkyl, C1-C4 alkoxy, hydroxyl, and amino.

2. A method for preparing the amide naphthoquinone organic electrode material according to claim 1, characterized in that: Adding a naphthoquinone compound, a compound of formula I or II, and a base to an organic solvent, stirring and reacting at 60 to 100° C. for 12 to 24 hours, cooling to room temperature after the reaction is completed, collecting the precipitate by filtration, washing with a washing solvent, and drying to obtain an amide naphthoquinone organic electrode material represented by formula A or B; In the formula, R1 represents a methyl group or a hydrogen atom, E represents a carbon or nitrogen atom, and R represents any one of hydrogen, nitro, cyano, fluorine, bromine, chlorine, C1-C4 alkyl, C1-C4 alkoxy, hydroxyl, and amino.

3. The method for preparing an amide naphthoquinone organic electrode material according to claim 2, characterized in that: The molar ratio of the naphthoquinone compound to the amide functional group in the compound of formula I or formula II is 1:1 to 2:

1.

4. The method for preparing an amide naphthoquinone organic electrode material according to claim 2, characterized in that: The base is any one of N,N-diisopropylethylamine, potassium carbonate and triethylamine.

5. The method for preparing an amide naphthoquinone organic electrode material according to claim 2 or 4, characterized in that: The molar ratio of the amide functional group to the base in the compound of formula I or formula II is 1:2 to 1:

4.

6. The method for preparing an amide naphthoquinone organic electrode material according to claim 2, characterized in that: The organic solvent is any one of N,N-dimethylformamide and acetonitrile.

7. The method for preparing an amide naphthoquinone organic electrode material according to claim 2, characterized in that: The washing solvents are N,N-dimethylformamide and ethanol.

8. Use of the amide naphthoquinone organic electrode material according to claim 1 as a positive electrode material in a lithium ion battery.

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