A pyridyl phenoxazine-based aqueous positive electrode material, a preparation method and application thereof

Abstract

This invention discloses a pyridylphenazine-based aqueous cathode material, its preparation method, and its applications, relating to the field of aqueous cathode material technology. The pyridylphenazine compounds provided by this invention, as cathode materials for aqueous batteries, solve the problems of structural collapse and capacity decay caused by the insertion of hydrated metal ions in existing inorganic materials. Based on a synergistic reaction mechanism of surface functional groups, they exhibit structural stability and excellent electrochemical performance when applied to aqueous zinc-ion batteries. The synthesis method of this invention is simple, and the reaction conditions are mild, which is conducive to large-scale production and commercial application. It can also be applied to various aqueous batteries, showing broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of aqueous cathode materials technology, and in particular to a pyridylphenazine-based aqueous cathode material, its preparation method, and its application. Background Technology

[0002] In today's world, energy and environmental issues are becoming increasingly prominent, making the establishment of a low-carbon and environmentally friendly new energy system imperative. While renewable energy sources such as solar and wind power have the advantages of being clean and renewable, they also suffer from intermittency and instability. Therefore, advanced energy storage technology is crucial for building a new energy system.

[0003] Among various aqueous metal-ion batteries, aqueous zinc-ion batteries are considered one of the most promising technologies for large-scale energy storage due to their inherent safety, low cost, environmental friendliness, and the high theoretical capacity of zinc (820 mAh g⁻¹). -1 It also has a lower redox potential (-0.76V vs. SHE). Currently, most inorganic materials, including manganese-based oxides, vanadium-based compounds, and Prussian blue analogues, benefit from the high hydration of Zn. 2+ The insertion of inorganic compounds causes structural collapse, resulting in significant capacity decay and limited cycle life. In contrast, organic materials, based on the cooperative reaction mechanism of surface functional groups, theoretically possess faster reaction kinetics. Therefore, developing novel organic cathode materials with stable structures is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a pyridylphenazine-based aqueous cathode material, its preparation method, and its application, in order to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] One of the technical solutions of this invention is to provide a pyridylphenazine compound having the structure shown in Formula I or Formula II:

[0007]

[0008] The present invention also provides a method for preparing the above-mentioned pyridylphenazine compounds, comprising the following steps:

[0009] Cyclohexane hexaone octahydrate and 2,3-diaminopyridine were subjected to a first reflux reaction in glacial acetic acid. After the reaction was completed, the mixture was washed and dried to obtain a pyridylphenazine compound with the structure shown in Formula I.

[0010] or

[0011] Cyclohexane hexaone octahydrate and 3,4-diaminopyridine were subjected to a second reflux reaction in glacial acetic acid. After the reaction was completed, the mixture was washed and dried to obtain a pyridylphenazine compound with the structure shown in Formula II.

[0012] As a further preferred embodiment of the present invention, the molar ratio of the cyclohexanehexane octhydrate to 2,3-diaminopyridine is 1:3; the molar ratio of the cyclohexanehexane octhydrate to 3,4-diaminopyridine is 1:3.

[0013] As a further preferred embodiment of the present invention, the temperature of the first reflux reaction is 110–140°C, and the time of the first reflux reaction is 7–10 h; the temperature of the second reflux reaction is 110–140°C, and the time of the second reflux reaction is 7–10 h.

[0014] As a further preferred embodiment of the present invention, the solvents used for the first and second washing processes include acetone, ethanol, and water.

[0015] As a further preferred embodiment of the present invention, the temperature of the first drying is 30-60°C and the time of the first drying is 8-12 hours; the temperature of the second drying is 30-60°C and the time of the second drying is 8-12 hours.

[0016] The second technical solution of the present invention provides the application of the above-mentioned pyridylphenazine compounds as positive electrode materials for aqueous batteries.

[0017] As a further preferred embodiment of the present invention, the aqueous battery includes an aqueous zinc-ion battery, an aqueous aluminum-ion battery, an aqueous calcium-ion battery, an aqueous sodium-ion battery, or an aqueous lithium-ion battery.

[0018] Current research indicates that the synthesis of some phenazine derivatives can be complex, requiring specialized reagents and reaction conditions, which can lead to high synthesis costs and hinder large-scale production and commercial applications. This invention, by introducing pyridine nitrogen atoms (electron-withdrawing groups), enhances the electrolyte wettability of the organic cathode. The increased number of active sites also improves the capacity of phenazine molecules. Furthermore, it shifts the redox potential of the cathode material to the right, facilitating charge transfer during charging and discharging and accelerating reaction kinetics. Additionally, the expanded π-conjugated structure enhances the structural stability of the electrode material. This invention allows for battery assembly in air, and the preparation method is simple, low-cost, and conducive to large-scale production and application.

[0019] The present invention discloses the following technical effects:

[0020] The pyridylphenazine compounds provided by this invention, as positive electrode materials for aqueous batteries, solve the problems of structural collapse and capacity decay caused by the insertion of hydrated metal ions in existing inorganic materials. Based on the synergistic reaction mechanism of surface functional groups, they have a stable structure and exhibit excellent electrochemical performance when applied to aqueous zinc-ion batteries.

[0021] The synthesis method of the material of this invention is simple, the reaction conditions are mild, which is conducive to large-scale production and commercial application. It can also be applied to a variety of aqueous batteries and has broad application prospects. Attached Figure Description

[0022] 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.

[0023] Figure 1 The Fourier transform infrared spectrum of the pyridylphenazine aqueous cathode material obtained in Example 1 of this invention is shown.

[0024] Figure 2 The Fourier transform infrared spectrum of the pyridylphenazine aqueous cathode material obtained in Example 2 of this invention is shown.

[0025] Figure 3 The pyridylphenazine-based aqueous cathode material prepared in Example 1 of this invention has a scan rate of 0.5 mV / s when used as a cathode material in an aqueous zinc-ion battery. -1 The CV diagram.

[0026] Figure 4 The charge-discharge curves of the pyridylphenazine aqueous cathode material prepared in Example 1 of this invention at different current densities are shown.

[0027] Figure 5 The pyridylphenazine-based aqueous cathode material prepared in Example 2 of this invention was tested at 1Ag. -1 The graph shows the long-cycle performance of an aqueous zinc-ion battery at a given current density.

[0028] Figure 6 This is a rate performance diagram of the pyridylphenazine-based aqueous cathode material prepared in Example 1 of the present invention.

[0029] Figure 7 This is a rate performance diagram of the pyridylphenazine-based aqueous cathode material prepared in Example 2 of the present invention.

[0030] Figure 8 The pyridylphenazine-based aqueous cathode material prepared in Example 1 of this invention was tested at 1Ag. -1The graph shows the long-cycle performance of an aqueous zinc-ion battery at a given current density.

[0031] Figure 9 This is a schematic diagram illustrating the working mechanism of the Zn / / QPNI battery during the discharge process of the present invention. Detailed Implementation

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] 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. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0035] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0036] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0037] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0038] Example 1

[0039] This embodiment provides a method for preparing a pyridylphenazine-based aqueous cathode material. The synthetic route is shown below:

[0040]

[0041] The preparation steps are as follows:

[0042] 1 mmol of cyclohexanehexaone octahydrate and 3 mmol of 2,3-diaminopyridine were placed in a three-necked flask. 50 ml of glacial acetic acid was added to the flask, followed by the addition of a polytetrafluoroethylene magnet. The flask was then placed in an oil bath and refluxed at 130 °C with stirring. The resulting liquid product was washed sequentially with acetone, anhydrous ethanol, and distilled water. The product was then dried in a vacuum drying oven at 40 °C for 8 h to obtain the pyridylphenazine aqueous cathode material (QPNI).

[0043] Preparation of aqueous zinc-ion batteries:

[0044] The pyridylphenazine-based aqueous cathode material prepared in Example 1 was mixed with acetylene black and polyvinylidene fluoride (PVDF) at a mass ratio of 7:2:1 and ground together. The resulting mixture was then dispersed in 3 ml of N-methyl-2-pyrrolidone (NMP) and uniformly coated onto a carbon cloth current collector. The electrode was then dried at 60°C for 2 hours to form the working electrode. Under air atmosphere, using 2.0 M ZnSO4 as the electrolyte, glass fiber as the separator, and a zinc sheet as the counter electrode, a CR2032 coin cell (labeled as a Zn / / QPNI cell) was assembled with a charge / discharge potential range of 0.2–1.6 V.

[0045] Example 2

[0046] This embodiment provides a method for preparing a pyridylphenazine-based aqueous cathode material. The synthetic route is shown below:

[0047]

[0048] The preparation steps are as follows:

[0049] 1 mmol of cyclohexanehexaone octahydrate and 3 mmol of 3,4-diaminopyridine were placed in a three-necked flask. 50 ml of glacial acetic acid was added to the flask, followed by the addition of a polytetrafluoroethylene magnet. The flask was then placed in an oil bath and refluxed at 130 °C with stirring. The resulting liquid product was washed sequentially with acetone, anhydrous ethanol, and distilled water. The product was then dried in a vacuum drying oven at 40 °C for 8 h to obtain the pyridylphenazine aqueous cathode material (QPNI).

[0050] Preparation of aqueous zinc-ion batteries:

[0051] The pyridylphenazine-based aqueous cathode material prepared in Example 2 was mixed with acetylene black and polyvinylidene fluoride (PVDF) at a mass ratio of 7:2:1 and ground together. The resulting mixture was then dispersed in 3 ml of N-methyl-2-pyrrolidone (NMP) and uniformly coated onto a carbon cloth current collector. The electrode was then dried at 60°C for 2 hours to form the working electrode. Under air atmosphere, using 2.0 M ZnSO4 as the electrolyte, glass fiber as the separator, and a zinc sheet as the counter electrode, a CR2032 coin cell (labeled as a Zn / / QPNI cell) was assembled with a charge / discharge potential range of 0.2–1.6 V.

[0052] Figure 1 This is the Fourier transform infrared spectrum of the pyridylphenazine-based aqueous cathode material obtained in Example 1 of this invention. For cyclohexanehexaone octahydrate, the spectrum can be obtained at 1641 cm⁻¹. -1 A peak value for the C=O vibration was found at [location missing], and the characteristic peak of the -NH2 group (3180 cm⁻¹) was observed after the dehydration condensation of cyclohexanehexaone octahedrate with 2,3-diaminopyridine. -1 The peaks for C=O and C=O disappeared, 1587 cm⁻¹ -1 The presence of a sharp characteristic peak resulting from a C=N bond indicates the successful synthesis of the compound.

[0053] Figure 2 This is the Fourier transform infrared spectrum of the pyridylphenazine-based aqueous cathode material obtained in Example 2 of this invention. For cyclohexanehexaone octahydrate, the spectrum can be obtained at 1641 cm⁻¹. -1 A peak value for the C=O vibration was found at [location missing], and the characteristic peak of the -NH2 group (3280 cm⁻¹) was observed after the dehydration condensation of cyclohexanehexaone octahedrate with 3,4-diaminopyridine. -1 The peaks for C=O and C=O disappeared, 1593 cm⁻¹ -1 The presence of a sharp characteristic peak resulting from a C=N bond indicates the successful synthesis of the compound.

[0054] Figure 3 The image shows the cyclic voltammetry curve of the 2032 button cell prepared in Example 1 of this invention at a scan rate of 0.5 mV s⁻¹. The cell exhibits three distinct pairs of redox peaks.

[0055] Figure 4 The figures show the charge-discharge curves of the 2032 button battery prepared in Example 1 of this invention at different current densities. As can be seen from the figures, the trends and plateaus of the charge-discharge curves remain consistent at different current densities, demonstrating the excellent rate performance of this pyridylphenazine-based aqueous cathode material.

[0056] Figure 5 The 2032 button cell prepared in Example 2 of this invention is tested at 1Ag. -1 The initial discharge specific capacity at the current density is 129 mAh g.-1 After 6000 cycles, the discharge specific capacity is 60 mAh g. -1 This demonstrates the excellent long-cycle performance of the pyridylphenazine-based aqueous cathode material.

[0057] Figure 6 The graph shows the rate performance of the 2032 button cell prepared in Example 2 of this invention at different current densities: 0.05, 0.2, 0.5, 1, 2, 5, and 0.05 Ag. -1 At current densities of 193, 150, 130, 110, 90, 63, and 164 mAg were obtained, respectively. -1 High discharge capacity.

[0058] Figure 7 The graph shows the rate performance of the 2032 button cell battery prepared in Example 1 of this invention at different current densities. The battery's rate performance is shown at current densities of 0.05, 0.1, 0.2, 0.5, 1, 2, and 5 Ag. -1 At current densities of 296, 260, 242, 218, 197, 179, and 153 mAg were obtained, respectively. -1 High discharge capacity. When the current density returns to the initial 0.05Ag. -1 At that time, the discharge capacity can still return to 259mAg. -1 This demonstrates that the material not only possesses excellent rate performance but also maintains superior reversibility.

[0059] Figure 8 The 2032 button cell prepared in Example 2 of this invention is tested at 1Ag. -1 It exhibits a discharge specific capacity of 268 mAh g at high current density. -1 Therefore, it can be concluded that the pyridylphenazine-based aqueous cathode material has high capacity and excellent cycle stability.

[0060] Figure 9 This is a schematic diagram illustrating the working mechanism of the Zn / / QPNI battery during the discharge process of the present invention.

[0061] The zinc storage mechanism is as follows: In a 2M ZnSO4 electrolyte, during discharge, C=N is reduced to CN, gaining 6 electrons, which combine with 3 zinc ions. During the subsequent charging process, CN is converted back to C=N, and the zinc ions dissociate from it. Throughout the charging and discharging process, zinc ions migrate back and forth between the positive and negative electrodes, realizing the energy storage and release of the battery.

[0062] anode:

[0063] cathode:

[0064]

[0065] In summary, the pyridylphenazine-based aqueous cathode material prepared in this invention exhibits excellent electrochemical performance and stability when applied to aqueous zinc-ion batteries.

[0066] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. The application of a pyridylphenazine compound as a positive electrode material in aqueous batteries, characterized in that, The pyridylphenazine compounds have the structure shown in Formula I or Formula II: Formula I Formula II.

2. The application according to claim 1, characterized in that, The aqueous batteries include aqueous zinc-ion batteries, aqueous aluminum-ion batteries, aqueous calcium-ion batteries, aqueous sodium-ion batteries, or aqueous lithium-ion batteries.

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