Isopyrazine compounds, methods of making, and use in making flexible binderless zinc-ion battery cathode materials

Abstract

The application discloses an isopyrazine compound, a preparation method and application thereof in preparation of a flexible binder-free zinc ion battery positive electrode material, and solves the problems of poor intrinsic conductivity and high solubility of an organic molecule by preparing a binder-free organic positive electrode material BMBF by compounding MXene (Ti3C2T x ) and a small molecule with an isopyrazine skeleton structure, simultaneously providing additional capacity by using the pseudo-capacitance characteristics of the MXene. The used organic small molecule is synthesized by tetraoxypyrimidine monohydrate in one step through a simple Schiff base reaction, which not only reduces the cost, but also simplifies the preparation process. The prepared aqueous zinc ion battery exhibits excellent electrochemical performance, including a higher specific capacity, excellent cycle stability and rate performance. The button cell can be stably cycled for more than 30,000 cycles at a current density of 3 Ag ‑1 , and always maintains a coulombic efficiency of about 100%.

Description

TECHNICAL FIELD

[0001] The present application relates to isochromazin compounds, preparation methods and their applications in the preparation of flexible binder-free zinc ion battery positive electrode materials. It belongs to the technical field of flexible zinc ion battery preparation. BACKGROUND

[0002] In recent years, the rapid development of technology has significantly promoted the advancement of flexible energy storage technology, injecting new vitality into the innovation of portable and wearable devices. As the market demand for portable devices rapidly grows, a variety of products such as small and delicate smartwatches, skin-attached medical detection devices, skin sensors, and foldable smartphones have emerged. The performance of these flexible electronic devices is greatly dependent on their energy storage components, and the size and mechanical properties of the energy storage devices largely determine the applicability of wearable devices in various use scenarios. Therefore, the development of both safe and efficient flexible energy storage devices is crucial for the future development of wearable electronic products. However, most commercial batteries on the market currently use components containing organic electrolytes and alkali metals, which are flammable and toxic to organic electrolytes, often causing environmental pollution and fire safety hazards. Considering these serious safety issues, aqueous zinc ion batteries (AZIBs) using water-based electrolytes with high safety factors have gradually become a new star in the field of flexible energy storage and are considered as a promising candidate for flexible energy storage devices.

[0003] Among existing organic electrode materials, organic carbonyl and imine compounds are increasingly attracting attention as high-performance positive electrode materials in AZIBs. Carbonyl and imine organic positive electrodes, such as quinones and pyrazines, have been extensively studied due to their rich redox-active sites. Their zinc storage mechanism is mainly through the reversible ionization of C=O or C=N bonds as effective active sites for zinc ion intercalation / deintercalation. In theory, quinone molecules with lower molecular weights and abundant active groups can achieve higher theoretical capacities.

[0004] In recent years, inspired by the biological energy metabolism in living organisms, people have studied parts of the redox behavior in living organisms, and these biologically inspired redox-active parts can undergo reversible redox reactions during charging and discharging. They can be overproduced by microorganisms or extracted from renewable biomass, such as humification of plant and animal matter. These renewable biomolecule-based electrochemical energy storage materials not only have environmental friendliness, biocompatibility, and sustainability, minimizing chemical waste and safety hazards, but also have good electrochemical performance, structural flexibility, and chemical diversity. For example, the isochromazin structure in flavin, nitrogen heterocycles in phenazine and viologen have been proven to reversibly store zinc ions through a double-ion transfer process.

[0005] In order to balance the flexibility and high performance of the positive electrode of the water system zinc ion battery, a high-performance flexible zinc ion battery positive electrode material is prepared, and it is necessary to develop a substrate material that meets both requirements. Using the substrate advantage of MXene, a flexible binder-free hybrid nano positive electrode is constructed, a polyvinyl alcohol (PVA) hydrogel electrolyte is used, and it is applied to AZIBs. The conductivity of the organic positive electrode and the stress-strain ability during the cycle process are improved. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of the prior art, provide an isopyrazine compound, a preparation method and its application in preparing a flexible binder-free zinc ion battery positive electrode material.

[0007] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0008] 1. An isopyrazine compound selected from any one of pyrimido[5,4-g]pteridine-2,4,6,8(1H,3H,7H,9H)-tetraone (PPT), naphtho[2,3-g]pteridine-2,4,6,11(1H,3H)-tetraone (NPT), and benzo[1,2-g:5,4-g']dipyridine-2,4,6,8,10,13(1H,3H,9H,11H)-hexaone (BDH), and their chemical structural formulas are as follows:

[0009]

[0010] 2. A preparation method of the aforementioned isopyrazine compound, comprising the following steps: first, adding tetraoxypyrimidine monohydrate and a reactant 2 into a reaction container, then adding glacial acetic acid and mixing uniformly, and then slowly dropping boric acid acetic acid solution into the reaction container, heating and stirring the reaction, and then treating to obtain the isopyrazine compound; wherein the reactant 2 is 5,6-amino-2,4(1H,3H)-pyrimidine dione, 2,3-diamino naphthalene-1,4-dione or 2,3,5,6-tetra(amino) p-benzoquinone, and the corresponding isopyrazine compounds are the aforementioned PPT, NPT and BDH respectively.

[0011] The reaction formula is as follows:

[0012]

[0013] Preferably, when the compound 2 is 5,6-amino-2,4(1H,3H)-pyrimidine dione or 2,3-diamino naphthalene-1,4-dione, the molar ratio of tetraoxypyrimidine monohydrate to compound 2 is 1:1-3, and further preferably 1:1-1.5; when the compound 2 is 2,3,5,6-tetra(amino) p-benzoquinone, the molar ratio of tetraoxypyrimidine monohydrate to compound 2 is 2-4:1, and further preferably 2-3:1.

[0014] Further preferably, the molar ratio of alloxan monohydrate to boric acid contained in the boric acid acetic acid solution is 1:1, and the usage ratio of alloxan monohydrate to glacial acetic acid is 1 mmol: 15 mL, wherein the boric acid acetic acid solution is obtained by dissolving boric acid in 10 times its molar ratio of glacial acetic acid.

[0015] Further preferably, the process conditions for heating and stirring the reaction are as follows: stirring rate 500 rpm, temperature 60°C, and stirring time 4-7 h; the stirring time is further preferably 4-6 h.

[0016] Further preferably, the post-treatment includes natural cooling to room temperature, vacuum filtration to obtain the precipitate, washing with deionized water and ethanol for 2-3 times in sequence, and then placing in a vacuum drying box for drying for 12 h.

[0017] 3. Use of the aforementioned isoazoline compound in the preparation of a flexible binder-free zinc ion battery positive electrode material.

[0018] 4. A flexible binder-free zinc ion battery positive electrode material (BM) prepared by compounding the aforementioned isoazoline compound as an active material and MXene as a flexible substrate.

[0019] Preferably, the MXene is prepared by the following method: slowly adding lithium fluoride to concentrated hydrochloric acid, mixing at room temperature, carefully adding Ti3AlC2 powder, heating and stirring the reaction, and then post-treating to obtain the MXene.

[0020] Further preferably, the usage ratio of concentrated hydrochloric acid, lithium fluoride, and Ti3AlC2 powder is 60 mL: 2 g: 2 g, and the concentration of the concentrated hydrochloric acid is 9 mol / L; the mixing time at room temperature is 20 min.

[0021] Further preferably, the process conditions for heating and stirring the reaction are as follows: stirring rate 500 rpm, temperature 40°C, and stirring time 24 h.

[0022] Further preferably, the post-treatment includes repeatedly centrifuging and washing with deionized water until the pH value of the solution exceeds 6; in order to separate the prepared MXene (Ti3C2T x ) layers, the MXene is dissolved and dispersed in deionized water, ultrasonic treatment is performed for 1 h under nitrogen protection to minimize oxidation, and a Ti3C2T x solution is obtained; finally, the Ti3C2T x solution is centrifuged at a speed of 4000 rpm for 1 h to obtain a single-layer or few-layer MXene suspension; wherein the usage ratio of MXene to deionized water is 1 g: 50 mL.

[0023] More preferably, the positive electrode material is prepared by the following method: first, the isoalloxazine compound is added to anhydrous ethanol and ultrasonically treated, then the MXene suspension is added, and ultrasonic treatment is carried out in an ice bath environment, ethanol is removed by rotary evaporation, and vacuum drying is performed to obtain the positive electrode material.

[0024] More preferably, the mass ratio of the isoalloxazine compound to the MXene suspension is 1:0.5-3, and more preferably 1:2-3, wherein the concentration of the isoalloxazine compound in the ethanol solution is 1 mg / mL. -1

[0025] More preferably, the ultrasonic treatment time of the isoalloxazine compound after being added to anhydrous ethanol is 0.5 h, and the ice bath ultrasonic treatment time after the MXene suspension is added is 1 h.

[0026] More preferably, the process conditions for removing ethanol by rotary evaporation are as follows: the rotation speed of the rotary evaporator is set to 100 rpm, and the temperature is 40°C.

[0027] More preferably, the temperature for vacuum drying is 40°C, and the drying time is 6 h.

[0028] 5. Use of the aforementioned positive electrode material in the preparation of a flexible zinc ion battery.

[0029] Preferably, the zinc ion battery is obtained by assembling and packaging a carbon cloth positive electrode containing the aforementioned positive electrode material, a zinc deposition carbon cloth, and a PVA hydrogel electrolyte in a sandwich structure.

[0030] Further preferably, the carbon cloth positive electrode is prepared by the following method: first, carbon black is uniformly dispersed in N-methyl pyrrolidone (NMP), then the aforementioned positive electrode material is added, and stirring is performed under sealed conditions until a suitable slurry in a thick and concentrated state is obtained, then the pretreated carbon cloth is fully immersed in the slurry, and after being taken out, vacuum drying is performed to obtain the carbon cloth positive electrode.

[0031] More preferably, the amount ratio of carbon black, positive electrode material, and NMP is 30 mg:120 mg:0.6 mL.

[0032] More preferably, stirring is performed at 800 rpm and room temperature for 24 h or more under sealed conditions.

[0033] More preferably, the judgment standard for a suitable thick and concentrated state is that when the container containing the slurry is placed upside down, the slurry slowly slides down the wall.

[0034] More preferably, the pretreated carbon cloth is obtained by sequentially ultrasonically cleaning the carbon cloth with deionized water and anhydrous ethanol for 30 min, and then vacuum drying at 60°C for 6 h.

[0035] More preferably, the soaking time is 1h; after taking out, vacuum drying at 80℃ for 12h.

[0036] Further preferably, the zinc-deposited carbon cloth is prepared by the following method: first, dissolving zinc sulfate, sodium sulfate and boric acid in distilled water to prepare an electrolyte, and then using the electrolyte to electrodeposit the pretreated carbon cloth by chronopotentiometry.

[0037] More preferably, the amount ratio of zinc sulfate, sodium sulfate, boric acid and distilled water is 20g:20g:4g:200mL.

[0038] More preferably, the pretreated carbon cloth is obtained by sequentially ultrasonic cleaning the carbon cloth with deionized water and anhydrous ethanol for 30min, and then vacuum drying at 60℃ for 6h.

[0039] More preferably, the electrodepositing is carried out at a constant current density of-15mA cm -2 for 30min.

[0040] Further preferably, the PVA hydrogel electrolyte is prepared by the following method: first, mixing polyvinyl alcohol (PVA) with anhydrous ethanol and deionized water, and heating and stirring for the first time, then slowly dropping zinc sulfate aqueous solution, heating and stirring for the second time, and naturally cooling to room temperature.

[0041] More preferably, the amount ratio of PVA, anhydrous ethanol, deionized water and zinc sulfate in the zinc sulfate aqueous solution is 1g:10mL:3mL:3.229g; the zinc sulfate aqueous solution is obtained by dissolving 3.229g of zinc sulfate in 5mL of deionized water.

[0042] More preferably, the process conditions for the first time of heating and stirring are stirring at 65℃ and 500rpm for 15min; and the process conditions for the second time of heating and stirring are stirring at 85℃ and 500rpm for 10min.

[0043] The beneficial effects of the present application are:

[0044] The present application solves the problems of poor intrinsic conductivity and high solubility of organic molecules by preparing a binder-free organic positive electrode material by compounding MXene as a flexible two-dimensional substrate with a small molecule having an isoazoline skeleton structure, and makes it have good flexibility, which can be applied to the preparation of flexible devices, and at the same time, the pseudo-capacitance characteristics of MXene provide additional capacity. And the positive electrode material has simple preparation steps, low overall preparation cost, and can realize mass production of materials. The application of a flexible organic positive electrode material of the present application is tested in a button cell, which exhibits excellent electrochemical performance, including high specific capacity, excellent cycle stability and rate performance. It can provide a specific capacity of 3Ag -1stable cycling at a current density of 1 A g-1 for more than 30,000 cycles with a coulombic efficiency of about 100% throughout. In addition, the study also reveals that the H + co-intercalation with Zn 2+ and a H + storage mechanism dominated by H -1 This work not only optimizes the organic electrode material from the perspectives of molecular structure and surface engineering, but also provides a new idea for the development of low-cost, high-performance and environmentally friendly rechargeable batteries. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 A preparation method flowchart of a battery positive electrode material of a MXene composite organic molecule prepared by the present application.

[0046] Figure 2 A scanning electron microscope (SEM) image of the positive electrode material prepared in Example 7 of the present application.

[0047] Figure 3 An (a) SEM image and corresponding (b) Ti, (c) O, (d) C, (e) N and (f) F element distribution energy spectrum (EDS) images of the positive electrode material prepared in Example 7 of the present application.

[0048] Figure 4 An assembly diagram of a flexible zinc ion battery assembled by a flexible positive electrode material of the present application.

[0049] Figure 5 A coin-type zinc ion battery assembled by the positive electrode material prepared in Example 8 of the present application, and its cycle performance at a current density of 1 A g -1

[0050] Figure 6 A coin-type zinc ion battery assembled by the positive electrode material prepared in Example 12 of the present application, and its cycle performance at a current density of 1 A g -1

[0051] Figure 7 The long cycle performance of a coin-type ion battery assembled by the positive electrode material of the present application at a current density of 3 A g -1

[0052] Figure 8 A display diagram of a flexible zinc ion battery assembled by the positive electrode material of the present application, which stably supplies power to an LED device with a voltage of 3.0 V under bending. DETAILED DESCRIPTION

[0053] The present application will be further described below in conjunction with the drawings and examples, and it should be noted that the following description is only for the purpose of explaining the present application and does not limit its content.

[0054] Example 1:​

[0055] Synthesis of Pyrimido[5,4-g]pteridine-2,4,6,8(1H,3H,7H,9H)-tetraone:

[0056]

[0057] Pyrimido[5,4-g]pteridine-2,4,6,8(1H,3H,7H,9H)-tetraone was synthesized by adding alloxan monohydrate (2.0 mmol, 320.18 mg) and 5,6-amino-2,4(1H,3H)- pyrimidinedione (2 mmol, 284.30 mg) into a 100 mL reaction tube, dissolving the reactants with glacial acetic acid (30 mL), then slowly dropping boric acid (2.0 mmol, 123.60 mg) dissolved in an appropriate amount of glacial acetic acid into the reaction tube, raising the reaction temperature to 60 °C, and stirring at 500 rpm for 6 h. After the temperature cooled to room temperature, the precipitate was obtained by vacuum filtration, washed with deionized water and ethanol 2-3 times in turn, and then placed in a vacuum drying oven to dry for 12 h to obtain the red product PPT (297.80 mg, 60% yield). 1 H NMR (500 MHz, DMSO-d6) δ 12.19 (s, 1H), 11.73 (s, 1H). MALDI-TOF (m / z): [M] + calculated for C8H4N6O4: 248.0186; found, 248.0183.

[0058] Example 2:

[0059] Pyrimido[5,4-g]pteridine-2,4,6,8(1H,3H,7H,9H)-tetraone was synthesized by adding alloxan monohydrate (2.0 mmol, 320.18 mg) and 5,6-amino-2,4(1H,3H)- pyrimidinedione (3 mmol, 426.45 mg) into a 100 mL reaction tube, dissolving the reactants with glacial acetic acid (30 mL), then slowly dropping boric acid (2.0 mmol, 123.60 mg) dissolved in an appropriate amount of glacial acetic acid into the reaction tube, raising the reaction temperature to 60 °C, and stirring at 500 rpm for 6 h. After the temperature cooled to room temperature, the precipitate was obtained by vacuum filtration, washed with deionized water and ethanol 2-3 times in turn, and then placed in a vacuum drying oven to dry for 12 h to obtain the red product PPT (322.62 mg, 65% yield).

[0060] Example 3:

[0061] Synthesis of Naphtho[2,3-g]pteridine-2,4,6,11(1H,3H)-tetraone:

[0062]

[0063] Tetraoxypyrimidine monohydrate (2.0 mmol, 320.18 mg) and 2,3-diaminonaphthalene-1,4-dione (2.0 mmol, 376.36 mg) were added to a 100 mL reaction tube, dissolved in glacial acetic acid (30 mL), then boric acid (2.0 mmol, 123.60 mg) was dissolved in an appropriate amount of glacial acetic acid and slowly dripped into the reaction tube, the reaction temperature was raised to 60 °C, and stirred at 500 rpm for 6 h. After the temperature was cooled to room temperature, the precipitate was obtained by vacuum filtration, washed with deionized water and ethanol for 2-3 times in turn, and then placed in a vacuum drying oven for drying for 12 h to obtain a green product NPT (494.31 mg, 84% yield). 1 H NMR (500 MHz, DMSO-d6) δ 11.84 (s, 1 H), 11.16 (s, 1 H), 7.43 (dd, J = 17.9, 6.6 Hz, 2H), 7.24 - 7.01 (m, 2H). MALDI-TOF (m / z): [M] + C 14 H6N4O4: 294.0281 ; found, 294.0285.

[0064] Example 4:

[0065] Tetraoxypyrimidine monohydrate (2.0 mmol, 320.18 mg) and 2,3-diaminonaphthalene-1,4-dione (3.0 mmol, 564.54 mg) were added to a 100 mL reaction tube, dissolved in glacial acetic acid (30 mL), then boric acid (2.0 mmol, 123.60 mg) was dissolved in an appropriate amount of glacial acetic acid and slowly dripped into the reaction tube, the reaction temperature was raised to 60 °C, and stirred at 500 rpm for 6 h. After the temperature was cooled to room temperature, the precipitate was obtained by vacuum filtration, washed with deionized water and ethanol for 2-3 times in turn, and then placed in a vacuum drying oven for drying for 12 h to obtain a green product NPT (506.08 mg, 86% yield).

[0066] Example 5:

[0067] Synthesis of benzo[1,2-g:5,4-g']dipyrido[3,4-b:2',3'-e]pyrazino[2,3-g]indolizine-2,4,6,8,10,13(1 H,3H,9H,11 H)-hexaone:

[0068]

[0069] Tetraoxypyrimidine monohydrate (3.0 mmol, 480.27 mg) and 2,3,5,6-tetra(amino) p-benzoquinone (1.0 mmol, 168.15 mg) were added to a 100 mL reaction tube, and the reaction was dissolved by adding glacial acetic acid (30 mL), then boric acid (2.0 mmol, 123.60 mg) was dissolved in an appropriate amount of glacial acetic acid and slowly dropped into the reaction tube, the reaction temperature was raised to 60°C, and stirred at 500 rpm for 6 h. After the temperature was cooled to room temperature, the precipitate was obtained by vacuum filtration, washed with deionized water and ethanol for 2-3 times, and then placed in a vacuum drying oven for 12 h to obtain a dark green product BDH (473.40 mg, 83% yield).

[0070] 1 H NMR (500 MHz, DMSO-d6): δ 12.68 (s, 1H), 12.02 (s, 1H), MALDI-TOF (m / z): [M] + calculated for C 14 H4N8O6: 380.0146; found, 380.0152.

[0071] Example 6:

[0072] Tetraoxypyrimidine monohydrate (3.0 mmol, 480.27 mg) and 2,3,5,6-tetra(amino) p-benzoquinone (1.0 mmol, 168.15 mg) were added to a 100 mL reaction tube, and the reaction was dissolved by adding glacial acetic acid (30 mL), then boric acid (2.0 mmol, 123.60 mg) was dissolved in an appropriate amount of glacial acetic acid and slowly dropped into the reaction tube, the reaction temperature was raised to 60°C, and stirred at 500 rpm for 6 h. After the temperature was cooled to room temperature, the precipitate was obtained by vacuum filtration, washed with deionized water and ethanol for 2-3 times, and then placed in a vacuum drying oven for 12 h to obtain a dark green product BDH (473.40 mg, 83% yield).

[0073] Example 7:

[0074] The preparation method of the BDH composite MXene positive electrode material of the embodiment of the present application and for the flexible zinc ion battery positive electrode comprises the following steps:

[0075] First, 80 mg of BDH powder was added to a round-bottom flask, then ethanol was added to the round-bottom flask, and the concentration of the BDH small molecule was kept below 1 mg mL -1The BDH dispersion solution is then ultrasonicated for more than 30 min to ensure that the BDH small molecules are uniformly dispersed in the ethanol solution. Then, 40 mg of MXene suspension is added. The above mixture is then ultrasonicated in an ice bath environment for 1 h. Then, the ethanol solvent in the mixture is slowly spin-dried using a rotary evaporator, with a rotation speed of 100 rpm and a temperature of 40°C. Finally, the obtained sample BM-67, in which BDH:MXene = 2:1 (w / w), is vacuum dried at 40°C for subsequent preparation of the positive electrode.

[0076] 0.03 g of carbon black (CB) is added to a 5 mL glass bottle, and after adding 0.5 mL of NMP, it is magnetically stirred until it is uniformly dispersed in the NMP. Then, 0.12 g of BM-67 is added, and then 0.1 mL of NMP solvent is slowly added dropwise, so that the slurry is just in a suitable thick state (when the glass bottle is placed upside down, the slurry slowly slides down the wall). After sealing the glass bottle, it is stirred at room temperature at a rotation speed of 800 rpm for more than 24 h to ensure that the components in the slurry are uniformly dispersed and mixed. The prepared slurry is coated and vacuum dried at 80°C for 12 h to completely remove the NMP solvent. The BM-67 positive electrode without using PVDF as the binder is named BMBF-67, which can be applied to flexible zinc ion batteries.

[0077] Please refer to Figure 1 , Figure 1 is a preparation method flowchart of the battery positive electrode material of the MXene composite organic molecule of Example 7 of the present application.

[0078] Please refer to Figure 2 , Figure 2 is a scanning electron microscope image (SEM) of the positive electrode material prepared in Example 7 of the present application.

[0079] Please refer to Figure 3 , Figure 3 is an elemental distribution energy spectrum (EDS) of the positive electrode material prepared in Example 7 of the present application.

[0080] Example 8:

[0081] A preparation method of a BDH composite MXene positive electrode material according to an embodiment of the present application and used in a flexible zinc ion battery positive electrode includes the following steps:

[0082] First, 60 mg of BDH powder is added to a round-bottom flask, and then a certain amount of ethanol is added to the round-bottom flask, so that the concentration of the BDH small molecules is kept below 1 mg mL -1The BDH dispersion solution is then ultrasonicated for more than 30 min to ensure that the BDH small molecules are uniformly dispersed in the ethanol solution. Then, 60 mg of the MXene suspension is added, and the mixture is ultrasonicated for 1 h in an ice bath environment. Then, the ethanol solvent in the mixture is slowly spin-dried using a rotary evaporator, with a rotation speed of 100 rpm and a temperature of 40°C. Finally, the obtained sample BM-50, in which BDH:MXene = 1:1 (w / w), is vacuum dried at 40°C for subsequent preparation of the positive electrode.

[0083] The 0.03 g of CB is added to a 5 mL glass bottle, and after adding 0.5 mL of NMP, it is magnetically stirred until it is uniformly dispersed in the NMP. Then, 0.12 g of BM-50 is added, and then 0.1 mL of NMP solvent is slowly added dropwise, so that the slurry is just in a suitable thick state (when the glass bottle is placed upside down, the slurry slowly slides down the wall). After sealing the glass bottle, it is stirred at a rotation speed of 800 rpm at room temperature for more than 24 h to ensure that the components in the slurry are uniformly dispersed and mixed. The prepared slurry is coated and vacuum dried at 80°C for 12 h to completely remove the NMP solvent. The BM-50 positive electrode without using PVDF as the binder is named BMBF-50, which can be applied to flexible zinc ion batteries.

[0084] Please refer to Figure 5 , Figure 5 is a cycle performance diagram of the positive electrode material prepared in Example 8 of the present application.

[0085] Example 9:

[0086] A preparation method of a BDH composite MXene positive electrode material according to an embodiment of the present application and used in a flexible zinc ion battery positive electrode includes the following steps:

[0087] First, 40 mg of BDH powder is added to a round-bottom flask, and then a certain amount of ethanol is added to the round-bottom flask, so that the concentration of the BDH small molecules is kept below 1 mg mL -1 After that, the BDH dispersion solution is ultrasonicated for more than 30 min to ensure that the BDH small molecules are uniformly dispersed in the ethanol solution. Then, 80 mg of the MXene suspension is added. Then, the mixture is ultrasonicated for 1 h in an ice bath environment. Then, the ethanol solvent in the mixture is slowly spin-dried using a rotary evaporator, with a rotation speed of 100 rpm and a temperature of 40°C. Finally, the obtained sample BM-33, in which BDH:MXene = 1:2 (w / w), is vacuum dried at 40°C for subsequent preparation of the positive electrode.

[0088] 0.03 g CB was added into a 5 mL glass bottle, and after adding 0.5 mL NMP, it was magnetically stirred until it was uniformly dispersed in NMP. Then 0.12 g BM-33 was added, and then 0.1 mL NMP solvent was slowly added dropwise, so that the slurry was just in a suitable thick state (when the glass bottle was placed upside down, the slurry slowly slid along the wall). After sealing the glass bottle, it was stirred at a speed of 800 rpm at room temperature for more than 24 h to ensure that the components in the slurry were uniformly dispersed and mixed. The prepared slurry was coated and vacuum dried at 80°C for 12 h to completely remove the NMP solvent. The BM-33 positive electrode without using PVDF as the binder was named BMBF-33, which can be applied to flexible zinc ion batteries.

[0089] Example 10:

[0090] The preparation method of the BDH composite MXene positive electrode material of the embodiment of the application and for the positive electrode of the flexible zinc ion battery comprises the following steps:

[0091] First, 30 mg of BDH powder was added to a round-bottom flask, and then a certain amount of ethanol was added to the round-bottom flask to keep the concentration of BDH small molecules below 1 mg mL -1 . Then the BDH dispersion was ultrasonicated for more than 30 min to ensure that the BDH small molecules were uniformly dispersed in the ethanol solution. Then 90 mg of MXene suspension was added. Then the above mixture was ultrasonicated in an ice bath environment for 1 h. Then the ethanol solvent in the mixture was slowly rotary evaporated, with a rotation speed of 100 rpm and a temperature of 40°C. Finally, the obtained sample BM-25, in which BDH: MXene = 1:3 (w / w), was vacuum dried at 40°C for subsequent positive electrode preparation.

[0092] 0.03 g CB was added into a 5 mL glass bottle, and after adding 0.5 mL NMP, it was magnetically stirred until it was uniformly dispersed in NMP. Then 0.12 g BM-33 was added, and then 0.1 mL NMP solvent was slowly added dropwise, so that the slurry was just in a suitable thick state (when the glass bottle was placed upside down, the slurry slowly slid along the wall). After sealing the glass bottle, it was stirred at a speed of 800 rpm at room temperature for more than 24 h to ensure that the components in the slurry were uniformly dispersed and mixed. The prepared slurry was coated and vacuum dried at 80°C for 12 h to completely remove the NMP solvent. The BM-33 positive electrode without using PVDF as the binder was named BMBF-33, which can be applied to flexible zinc ion batteries.

[0093] Example 11:

[0094] The preparation method of the BDH composite MXene positive electrode material of the embodiment of the application and for the positive electrode of the flexible zinc ion battery comprises the following steps:

[0095] 0.03g CB was added into a 5mL glass bottle, and after adding 0.4mL NMP, it was magnetically stirred until it was uniformly dispersed in NMP. Then 0.07g BM was added, and then 0.1mL NMP solvent was continuously added dropwise at a slow speed, so that the slurry was just in a suitable thick state (when the glass bottle was placed upside down, the slurry slowly slid along the wall). After sealing the glass bottle, it was stirred at a speed of 800rpm at room temperature for more than 24h to ensure that the components in the slurry were uniformly dispersed and mixed. The prepared slurry was coated and vacuum dried at 80℃ for 12h to completely remove the NMP solvent. Among them, BM:CB=7:3(w / w), which can be applied to flexible zinc ion batteries.

[0096] Example 12:

[0097] The preparation method of the BDH composite MXene positive electrode material of the embodiment of the application and for the positive electrode of the flexible zinc ion battery comprises the following steps:

[0098] 0.03g CB was added into a 5mL glass bottle, and after adding 0.4mL NMP, it was magnetically stirred until it was uniformly dispersed in NMP. Then 0.07g BM was added, and then 0.1mL NMP solvent was continuously added dropwise at a slow speed, so that the slurry was just in a suitable thick state (when the glass bottle was placed upside down, the slurry slowly slid along the wall). After sealing the glass bottle, it was stirred at a speed of 800rpm at room temperature for more than 24h to ensure that the components in the slurry were uniformly dispersed and mixed. The prepared slurry was coated and vacuum dried at 80℃ for 12h to completely remove the NMP solvent. Among them, BM:CB=7:3(w / w), which can be applied to flexible zinc ion batteries.

[0099] Please refer to Figure 6 , Figure 6 is the cycle performance diagram of the positive electrode material prepared in Example 12 of the application.

[0100] Example 13:

[0101] The preparation method of the BDH composite MXene positive electrode material of the embodiment of the application and for the positive electrode of the flexible zinc ion battery comprises the following steps:

[0102] CB was added into a 5 mL glass bottle, and after 0.6 mL NMP was added, it was magnetically stirred until it was uniformly dispersed in NMP. Then 0.18 g BM was added, and then 0.1 mL NMP solvent was continuously added slowly, so that the slurry was just in the right thick state (when the glass bottle was placed upside down, the slurry slowly slid down along the wall). After the glass bottle was sealed, it was stirred at room temperature for more than 24 h at a rotation speed of 800 rpm to ensure that the components in the slurry were uniformly dispersed and mixed. The prepared slurry was coated and vacuum dried at 80°C for 12 h to completely remove the NMP solvent. Among them, BM:CB = 9:1 (w / w), which can be applied to flexible zinc ion batteries.

[0103] Example 14:

[0104] Button cell assembly: BM BF-25 / 1M ZnS04+2M Na2S04 / Zn

[0105] The prepared positive electrode was cut into a 12 mm diameter disc, a 0.1 mm thick zinc foil was cut into a 17 mm diameter disc, and a glass fiber separator was cut into a 19 mm diameter disc. A 304 stainless steel battery shell of CR2025 type was used. The battery was assembled in the following order: positive electrode shell-positive electrode-100 μL electrolyte-separator-100 μL electrolyte-negative electrode-wavy spring washer-gasket-negative electrode shell. Finally, it was packaged with a tablet press.

[0106] Example 15:

[0107] Flexible battery assembly: BM BF-25 / PVA hydrogel electrolyte / Zn

[0108] The prepared carbon cloth positive electrode, zinc deposition carbon cloth and PVA hydrogel electrolyte were cut into the appropriate shape, and finally the three components were assembled together in a sandwich structure and packaged with ordinary transparent tape.

[0109] Please refer to Figure 4 , Figure 4 is a schematic diagram of the flexible battery prepared in Example 15 of the present application, Figure 8 is a display diagram of the practical application of the flexible battery prepared in Example 15 of the present application.

[0110] According to the above structure, it was prepared and characterized as the performance of the positive electrode of aqueous zinc ion battery. It was stably cycled more than 30,000 times at a current density of 3 Ag -1 , and maintained a coulombic efficiency of about 100% (η) Figure 7 ) all the time.

[0111] In order to prove the good versatility of the prepared positive electrode material as the positive electrode of the flexible zinc ion battery, the positive electrode material is further assembled into a flexible zinc ion battery. Satisfactorily, the positive electrode can still stably supply power to the LED device with a voltage of 3.0 V after repeated shearing. Therefore, the prepared positive electrode of the flexible zinc ion battery can adapt to various application scenarios of the flexible battery, and has great application prospect in the field of flexible devices.

[0112] Although the specific embodiments of the present application are described above in combination with the drawings, the description is not a limitation on the scope of protection of the present application. Various modifications or variations made by those skilled in the art on the basis of the technical solutions of the present application without creative labor are still within the scope of protection of the present application.

Claims

1. An isopyrrolizine compound characterized by, Any one selected from naphtho[2,3-g]pteridine-2,4,6,11(1H,3H)-tetraone, benzo[1,2-g:5,4-g']bisopteridine-2,4,6,8,10,13(1H,3H,9H,11H)-hexaone, the chemical structural formula of which is as follows:

2. Use of a compound for the preparation of a flexible binderless zinc-ion battery cathode material, characterized in that, The compound is selected from pyrimido[5,4-g]pteridine-2,4,6,8(1H,3H,7H,9H)-tetraone or the isoalloxazine compound of claim 1, and the chemical structural formula of the pyrimido[5,4-g]pteridine-2,4,6,8(1H,3H,7H,9H)-tetraone is as follows:

3. A flexible binder-free zinc-ion battery cathode material, characterized in that, The compound is selected from pyrimido[5,4-g]pteridine-2,4,6,8(1H,3H,7H,9H)-tetraone or the isoalloxazine compound of claim 1, and the chemical structural formula of the pyrimido[5,4-g]pteridine-2,4,6,8(1H,3H,7H,9H)-tetraone is as follows:

4. The flexible binder-less zinc-ion battery positive electrode material of claim 3, wherein, The MXene is prepared by the following method: first, lithium fluoride is slowly added to concentrated hydrochloric acid, mixed at room temperature, carefully added with Ti3AlC2 powder, heated and stirred for reaction, and then treated to obtain the MXene.

5. Use of the positive electrode material of claim 4 in the preparation of a flexible zinc ion battery.

6. Use according to claim 5, characterized in that, The zinc ion battery is obtained by assembling and packaging the carbon cloth positive electrode containing the aforementioned positive electrode material, zinc deposition carbon cloth and PVA hydrogel electrolyte in a sandwich structure.

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