A ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode and its application in aqueous batteries

Abstract

The invention discloses a ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode and its application in aqueous batteries, belonging to the technical field of battery preparation. Ruthenium oxide and diphenylamine are loaded onto graphene by physical adsorption to obtain RuO 2 / DPA / C composite material; RuO 2 The / DPA / C composite material is mixed with iodine and heated for reaction to obtain a ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode. The aqueous zinc ion battery is assembled using the ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode as the positive electrode material. The present invention loads ruthenium oxide and diphenylamine on graphene to prepare a bidirectionally stable iodine electrode; the aqueous battery constructed with this electrode not only solves the stability problem of iodine positive and negative ions in the electrolyte, avoids the use of chloride ions or bromide ions, and realizes deep charging and discharging of the iodine electrode, but also avoids the uneven deposition of intermediate iodine elements through intermolecular recombination, greatly improving the comprehensive performance of the battery.

Description

Technical Field

[0001] The invention relates to the technical field of battery preparation, and in particular to a ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode and application thereof in an aqueous battery. Background Art

[0002] With the rapid growth of global energy demand and increasing attention to environmental protection, efficient, safe and sustainable energy storage technology has become an indispensable part of the modern energy system. As a new type of electrochemical energy storage device, iodine electrode has attracted widespread attention due to its abundant zinc resources, low cost, environmental friendliness and multivalent properties of iodine. However, although zinc-iodine batteries have high energy density and good safety in theory, they still face a series of challenges in practical applications, especially the iodine cation (I cation) during battery cycling. + ) hydrolysis reaction and iodide anion (I - ) instability problem. These problems directly lead to the rapid attenuation of battery performance and limit the large-scale application of zinc-iodine batteries. In order to solve these problems, researchers have conducted extensive research and explored a variety of possible solutions, including optimization of electrolytes, stabilization of iodine positive and negative ions, and improvement of electrode materials. In these studies, researchers generally use chloride ions and bromide ions to stabilize iodine positive ions. However, the use of chloride ions or bromide ions will bring serious corrosion, affecting the service life of the equipment. Special anti-corrosion equipment is required for use, which greatly increases the manufacturing cost and hinders the development of deep discharge of iodine electrodes.

[0003] Diphenylamine (DPA) is a promising functional material due to its unique electronic structure. However, diphenylamine is currently mainly used in the preparation of organic solar cells, such as perovskite batteries. There are few reports on the application of diphenylamine in aqueous batteries. Application No. 202210934861.1 discloses a high-stability secondary aqueous iron-polymer battery, its positive electrode and preparation method, using diphenylamine as a cross-linking point to increase the speed of electron transmission. However, for aqueous zinc-ion batteries, the key is how to improve the bidirectional stability of iodide ions. Therefore, a bidirectionally stable iodine electrode containing diphenylamine is needed. Summary of the invention

[0004] In view of the above-mentioned prior art, the purpose of the present invention is to provide a ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode and its application in aqueous batteries. The present invention loads ruthenium oxide and diphenylamine on graphene to prepare a bidirectionally stable iodine electrode; the aqueous battery constructed with this electrode not only solves the stability problem of iodine positive and negative ions in the electrolyte, avoids the use of chloride ions or bromide ions, and realizes deep charging and discharging of the iodine electrode, but also avoids the uneven deposition of intermediate iodine element through intermolecular recombination, greatly improving the comprehensive performance of the battery.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] In a first aspect of the present invention, a ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode is provided, which is prepared by the following method:

[0007] (1) RuO2 / DPA / C composite material was obtained by loading ruthenium oxide and diphenylamine (DPA) onto graphene by physical adsorption;

[0008] (2) The RuO2 / DPA / C composite material is mixed with iodine and heated to react to obtain a ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode.

[0009] Preferably, in step (1), the mass ratio of ruthenium oxide, diphenylamine and graphene is 1:5:25.

[0010] Preferably, in step (1), the physical adsorption method includes grinding and mixing or mixing in a medium.

[0011] Preferably, the mixing in a medium is to disperse graphene in water, add ruthenium oxide and diphenylamine, and stir.

[0012] Preferably, in step (2), the mass ratio of the RuO2 / DPA / C composite material to iodine is 1:10.

[0013] Preferably, in step (2), the heating reaction temperature is 120° C. and the heating reaction time is 4 h.

[0014] In a second aspect of the present invention, a ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode is provided for use in at least one of the following 1) to 4):

[0015] 1) Preparation of aqueous zinc ion batteries;

[0016] 2) Promote uniform deposition of iodine;

[0017] 3) Inhibit the hydrolysis reaction of iodine cations;

[0018] 4) Improve the depth of charge and discharge of the iodine electrode.

[0019] The third aspect of the present invention provides an aqueous zinc ion battery, wherein the aqueous zinc ion battery uses a ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode as a positive electrode material, zinc as a negative electrode material, and a zinc salt aqueous solution as an electrolyte.

[0020] Preferably, the zinc salt aqueous solution is zinc sulfate, zinc perchlorate or zinc trifluoromethanesulfonate.

[0021] A fourth aspect of the present invention provides an application of an aqueous zinc ion battery in improving battery cycle stability.

[0022] Beneficial effects of the present invention:

[0023] (1) In the ruthenium oxide-catalyzed diphenylamine bidirectional stable iodine electrode prepared by the present invention, the electron pairs carried by the iodine element will form p-π conjugation with the benzene ring on the diphenylamine, so that the iodine is fully loaded on the surface of the diphenylamine, and the intermolecular composite RuO2 / DPA / C@I2 electrode material is obtained. The intermolecular composite is conducive to the adsorption of the iodine element and promotes the uniform deposition of iodine. RuO2 is used as a catalyst, and its potential (1.1 V vs. SHE) is matched with the redox potential of the iodine cation to achieve a synergistic catalytic reaction, which can reduce the reaction barrier and achieve the redox of the highly reactive iodine cation.

[0024] (2) The preparation method of the ruthenium oxide-catalyzed diphenylamine bidirectional stable iodine electrode prepared by the present invention is simple, which can promote the uniform deposition of iodine; inhibit the hydrolysis reaction of iodine cations; and improve the deep charge and discharge of the iodine electrode.

[0025] (3) The aqueous zinc ion battery prepared by the present invention greatly improves the electrical performance of aqueous batteries, especially the cycle stability of the battery. It will bring new development opportunities to the field of electrochemical energy storage and promote the development of energy storage technology towards a more efficient, safer and more sustainable direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 : Charge and discharge curves of C@I2 at different current densities in Comparative Example 1;

[0027] Figure 2 : Cyclic voltammetry curves of C@I2 at different scanning speeds in Comparative Example 1;

[0028] Figure 3 :In Comparative Example 1, C@I2 at 2 A g -1 1-200 cycles of charge and discharge curve at current density;

[0029] Figure 4 : Scanning diagram of DPA / C in Comparative Example 2;

[0030] Figure 5 : Scanning mapping diagram of DPA / C in Comparative Example 2;

[0031] Figure 6 : Infrared spectrum of DPA / C in Comparative Example 2;

[0032] Figure 7 : Charge and discharge curves of DPA / C@I2 at different current densities in Comparative Example 2;

[0033] Figure 8 : Cyclic voltammetry curves of DPA / C@I2 at different scanning speeds in Comparative Example 2;

[0034] Fig. 9 : In comparative example 2, DPA / C@I2 at 2 A g -1 1-200 cycles of charge and discharge curve at current density;

[0035] Fig.10 : Schematic diagram of the bidirectional stabilization structure of diphenylamine and iodide ion;

[0036] Fig.11 : Scanning electron microscope image of RuO2 / DPA / C in the embodiment;

[0037] Fig.12 : Scanning mapping of RuO2 / DPA / C in the embodiment;

[0038] Fig.13 : Charge and discharge curves of RuO2 / DPA / C@I2 at different current densities in the embodiment;

[0039] Fig.14 : Cyclic voltammetry curves of RuO2 / DPA / C@I2 at different scanning speeds in the embodiment;

[0040] Fig.15 :RuO2 / DPA / C@I2 in 2 A g -1 1-200 cycles of charge and discharge curves at current density. DETAILED DESCRIPTION

[0041] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0042] As introduced in the background technology section, zinc-iodine batteries theoretically have high energy density and good safety. However, they still face a series of challenges in practical applications, especially the iodine cation (I + ) hydrolysis reaction and iodide anion (I - These problems directly lead to the rapid attenuation of battery performance and limit the large-scale application of zinc-iodine batteries.

[0043] Based on this, the purpose of the present invention is to provide a ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode and its application in aqueous batteries. +) is stabilized by chloride ions or bromide ions, but these ions are highly corrosive. The present invention uses diphenylamine for stabilization, avoiding the use of chloride ions or bromide ions, which is more conducive to the practical application of iodine electrodes. The bidirectional stability mentioned in the present invention refers to the use of nitrogen anions in the molecular structure of diphenylamine in the charged state and iodine positive ions (I + ) effectively inhibits the hydrolysis reaction of iodine cations; at the same time, the nitrogen cations in the discharge process of diphenylamine can stabilize the iodine anions (I - ), preventing the generation of polyiodide on the electrode surface and dissolution, thereby achieving deep charge and discharge of the iodine electrode (I + —I - ).

[0044] Diphenylamine not only has a large conjugated electronic structure, but also has the ability to protonate and deprotonate its nitrogen atoms. If diphenylamine is used to prepare a bidirectional stable iodine electrode for use in an aqueous zinc ion battery, it can not only solve the stability problem of iodine positive and negative ions in the electrolyte, avoid the use of chloride ions or bromide ions, and achieve deep charging and discharging of the iodine electrode; it can also avoid the uneven deposition of intermediate iodine elements through intermolecular recombination, greatly improving the overall performance of the battery. Therefore, the present invention uses the nitrogen positive ions in diphenylamine to react with iodine negative ions (I - ) to form a stable compound, which can not only prevent I - On the other hand, the nitrogen anions of diphenylamine in the diphenylamine composite material can coordinate with the iodine ions (I + ) form a stable complex, thereby inhibiting I +Hydrolysis reaction with water during the battery cycle. This hydrolysis reaction usually generates iodate or other unstable byproducts, resulting in a decrease in the coulombic efficiency of the battery and a shortened cycle life. Through stable combination with nitrogen anions, the stability of iodine cations is improved, and its stability in the electrolyte is also effectively enhanced, thereby avoiding the use of chloride ions and bromide ions. Therefore, the diphenylamine used in the present invention forms nitrogen cations and nitrogen anions through protonation and deprotonation of nitrogen atoms, respectively, thereby performing preliminary bidirectional stabilization of iodine cations and iodine anions. Although the addition of phenylenediamine to the aqueous battery constructed with electrodes prepared from diphenylamine and iodide ions preliminarily achieves bidirectional stability of the battery, the kinetics of the battery are slow and the reaction is not fast enough. Therefore, the present application studies the addition of ruthenium oxide as a catalyst, as a material that matches the redox potential of iodine cations, to synergistically catalyze this reaction process, reduce the reaction energy barrier of the reaction, and achieve the redox of highly reactive iodine cations. In addition, the electron pairs carried by the iodine element will form p-π conjugation with the benzene ring on diphenylamine, so that the iodine can be fully loaded on the surface of diphenylamine to obtain an intermolecular composite material, avoiding uneven deposition of iodine. The addition of ruthenium oxide accelerates the reaction kinetics.

[0045] In summary, the ruthenium oxide / diphenylamine composite material not only solves the stability problem of iodine positive and negative ions in the electrolyte, avoids the use of chloride ions or bromide ions, and realizes the deep charge and discharge of the iodine electrode, but also avoids the uneven deposition of intermediate iodine elements through intermolecular complexation, greatly improving the overall performance of the battery. The introduction of this innovative technology will bring new development opportunities to the field of electrochemical energy storage and promote the development of energy storage technology in a more efficient, safer and more sustainable direction.

[0046] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with specific embodiments.

[0047] The test materials used in the examples of the present invention are all conventional test materials in the art and can be purchased through commercial channels.

[0048] Example

[0049] (1) Preparation of RuO2 / DPA / C: 500 mg of graphene was dispersed in 100 mL of water to obtain a graphene aqueous dispersion, and 250 mg of DPA was dissolved in 50 mL of water to obtain a DPA solution. 100 mL of graphene aqueous dispersion (5 mg / mL) was placed in a 250 mL flask, and 50 mL of DPA solution (5 mg / mL) and 50 mg of ruthenium oxide powder were added, and stirred at room temperature (25°C) for 30 min. After filtering, the obtained precipitate was washed several times with deionized water, and then vacuum dried at 80°C for 6 h to obtain the RuO2 / DPA / C material.

[0050] (2) Preparation of RuO2 / DPA / C@I2: 200 mg of RuO2 / DPA / C material was placed in a 5 mL glass bottle and placed in the liner of an autoclave. 2 g of iodine was spread on the bottom of the autoclave outside the glass bottle. The autoclave was sealed and kept at 120 °C for 4 h to allow the iodine to sublime. The steam entered the RuO2 / DPA / C material. Since the electron pairs carried by the iodine will form p-π conjugation with the benzene ring on the diphenylamine, the iodine is fully loaded on the surface of the diphenylamine to obtain the intermolecular composite RuO2 / DPA / C@I2.

[0051] (3) Assembly of zinc-iodine battery: Use RuO2 / DPA / C@I2 as the positive electrode, bare zinc as the negative electrode, 3M zinc sulfate as the electrolyte, and 100 μm thick glass fiber as the separator to assemble button-type 2032 batteries.

[0052] Comparative Example 1

[0053] (1) Preparation of C@I2: 200 mg of graphene material was placed in a 5 mL glass bottle and placed in an autoclave liner. 2 g of iodine was spread on the bottom of the autoclave outside the glass bottle. The autoclave was sealed and kept at 120 °C for 4 h to allow iodine to sublime and the steam to enter the C material to obtain C@I2.

[0054] (2) Assembly of zinc-iodine battery: Use C@I2 as the positive electrode, bare zinc as the negative electrode, 3M zinc sulfate as the electrolyte, and 100 μm thick glass fiber as the separator to assemble button-type 2032 batteries.

[0055] Comparative Example 2

[0056] (1) Preparation of DPA / C: 500 mg of graphene was dispersed in 100 mL of water to obtain a graphene aqueous dispersion, and 250 mg of DPA was dissolved in 50 mL of water to obtain a DPA solution. 100 mL of the graphene aqueous dispersion (5 mg / mL) was placed in a 250 mL flask, and the DPA solution (5 mg / mL) was added and stirred at room temperature (25°C) for 30 min. After filtering, the obtained precipitate was washed several times with deionized water and vacuum dried to obtain the DPA / C material.

[0057] (2) Preparation of DPA / C@I2: 200 mg of DPA / C material was placed in a 5 mL glass bottle and placed in an autoclave liner. 2 g of iodine was spread on the bottom of the autoclave outside the glass bottle. The autoclave was sealed and kept at 120 °C for 4 h to allow iodine to sublime and steam to enter the DPA / C material to obtain DPA / C@I2 material.

[0058] (3) Assembly of zinc-iodine battery: Use DPA / C@I2 as the positive electrode, bare zinc as the negative electrode, 3M zinc sulfate as the electrolyte, and 100 μm thick glass fiber as the separator to assemble button-type 2032 batteries.

[0059] Test example

[0060] The performance of the assembled button-type 2032 batteries prepared in Example 1 and Comparative Examples 1-2 was tested using Chenhua CHI660E and Blue Power CT2001A electrochemical workstations. Figures 1 to 15 shown.

[0061] Figure 1 The charge and discharge curves at different current densities in Comparative Example 1 are shown. −1 When the C@I2 positive electrode has only one charging and discharging platform, the electron utilization rate is low, and the battery capacity is lower than that of the embodiment. Figure 2 The cyclic voltammetry curves of C@I2 at different scan rates in Comparative Example 1 show that within the voltage range of 0.6 V-1.9 V, there is only a pair of obvious redox peaks at the positive electrode of C@I2, with the oxidation peak voltage being about 1.3 V and the reduction peak voltage being about 1.2 V. When the scan rate is 2 mV / S, the oxidation peak current is about 0.17 mA and the reduction peak current is about -0.25 mA. Figure 3 They represent the C@I2 positive electrode in comparative example 1 at a current density of 2 A g -1 The 1-200 cycle curve and charge-discharge curve are shown below. The battery discharge capacity increases from 95 mAh g to 1.5 mAh g after 200 cycles. -1 Down to 55 mAh g -1 Compared with the embodiment, the battery capacity and cycle stability without diphenylamine loading are poor, which is mainly due to the fact that only I2 and I - The reaction between them cannot be realized because there is no stable structure. + stable existence.

[0062] Figure 4 This is the scanning electron microscope image of DPA / C in Comparative Example 2. Figure 5 This is the mapping diagram of DPA / C in scale 2. It can be seen that the N elements are evenly distributed in DPA / C. Figure 6 This is the infrared spectrum of DPA / C in Comparative Example 2, confirming the existence of NH, C=C / C=N, and CN bonding. Figure 7 The charge and discharge curves of Comparative Example 2 at different current densities are shown. After diphenylamine and iodine are combined, the current densities are 0.5, 1, 2, and 5 A g -1 The discharge specific capacities are 190, 145.8, 124, and 105.9 mAh g -1The dual charge and discharge platform more intuitively demonstrates that the bidirectional stabilization mechanism of diphenylamine enables deep charge and discharge of the iodine electrode. Compared with comparative example 1, the bidirectional stabilization mechanism of diphenylamine load achieves deep charge and discharge of the iodine electrode (I + —I - ), which is beneficial to improving the electrochemical performance of the battery. Figure 8 Representative cyclic voltammetry curves of DPA / C@I2 positive electrode battery at different scan rates. In the voltage range of 0.6 V-1.9 V, there are two pairs of obvious redox peaks in the DPA / C@I2 positive electrode. The peak voltages of the oxidation peaks are approximately 1.19 V and 1.77 V, and the peak voltages of the reduction peaks are approximately 1.09 V and 1.67 V. Fig. 9 The DPA / C@I2 cathode in Comparative Example 2 is at a current density of 2 A g -1 The 1-200 cycle length curve and charge-discharge curve are shown below. The battery discharge capacity increases from 122 mAh g to 200 mAh g after 200 cycles. -1 Down to 81 mAh g -1 , the capacity is higher than that of comparative example 1.

[0063] Fig.11 This is a scanning electron microscope image of RuO2 / DPA / C prepared in Example. Fig.12 The mapping diagram of RuO2 / DPA / C prepared in the example shows that Ru, O, and N elements are evenly distributed in RuO2 / DPA / C, indicating that the composite material was successfully prepared. Fig.13 The charge and discharge curves of the embodiment at different current densities are shown. The ruthenium oxide catalyzed diphenylamine composite electrode has a current density of 0.5, 1, 2, and 5 A g -1 The discharge specific capacities are 200, 175, 150, and 108 mAh g -1 The dual charge and discharge platform more intuitively demonstrates that the bidirectional stabilization mechanism of diphenylamine enables the deep charge and discharge of the iodine motor. At the same time, the increase in capacity proves the existence of the catalytic effect of ruthenium oxide. Compared with Comparative Examples 1 and 2, the bidirectional stabilization mechanism of diphenylamine loading realizes the deep charge and discharge of the iodine electrode (I + —I - ), which is beneficial to improving the electrochemical performance of the battery. Fig.14 The cyclic voltammetry curves of RuO2 / DPA / C@I2 at different scanning rates in the example are as follows. In the voltage range of 0.6 V-1.9 V, there are two pairs of obvious redox peaks at the positive electrode, which also confirms the results of the charge and discharge curves. Fig.15 The RuO2 / DPA / C@I2 positive electrode in the embodiment is at a current density of 2 A g -1 The 1-200 cycle curve and charge-discharge curve are shown below. The battery discharge capacity increases from 151 mAh g to 200 mAh g after 200 cycles. -1 Down to 147 mAh g-1 Compared with comparative example 1, the bidirectional stabilization mechanism increases the battery capacity while achieving multi-electron transfer; compared with comparative example 2, the addition of ruthenium oxide catalyzes the reaction, reduces the reaction energy barrier, and improves the cycle stability to a certain extent. The schematic diagram of the bidirectional stabilization mechanism is shown in Fig.10 As shown in the figure, due to the nitrogen anion in the diphenylamine molecular structure and the iodine cation (I + ) effectively inhibits the hydrolysis reaction of iodine cations; at the same time, the nitrogen cations in the discharge process of diphenylamine can stabilize the iodine anions (I - ), preventing the generation of polyiodide on the electrode surface and dissolution, thereby achieving deep charge and discharge of the iodine electrode (I + —I - ). Compared with Comparative Examples 1 and 2, the RuO2 / DPA / C prepared in Example 1 further improves the electron utilization rate of the iodine electrode during the redox reaction, and the bidirectional loading mechanism increases the battery capacity while further improving the cycle stability.

[0064] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode, characterized in that: Prepared by the following method: (1) loading ruthenium oxide and diphenylamine onto graphene by physical adsorption to obtain a RuO2 / DPA / C composite material; the mass ratio of ruthenium oxide, diphenylamine and graphene is 1:5:25; (2) The RuO2 / DPA / C composite material is mixed with iodine, and heated to react to obtain a ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode; the mass ratio of the RuO2 / DPA / C composite material to iodine is 1:

10.

2. The ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode according to claim 1, characterized in that: In step (1), the physical adsorption method includes grinding and mixing or mixing in a medium.

3. The ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode according to claim 2, characterized in that: The mixing in the medium is to disperse graphene in water, add ruthenium oxide and diphenylamine, and stir.

4. The ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode according to claim 1, characterized in that: In step (2), the heating reaction temperature is 120° C. and the heating reaction time is 4 h.

5. The use of the ruthenium oxide-catalyzed diphenylamine bidirectionally stable iodine electrode according to any one of claims 1 to 4 in at least one of the following 1) to 4): 1) Preparation of aqueous zinc ion batteries; 2) Promote uniform deposition of iodine; 3) Inhibit the hydrolysis reaction of iodine ions; 4) Improve the depth of charge and discharge of the iodine electrode.

6. An aqueous zinc ion battery, characterized in that: The aqueous zinc ion battery uses the ruthenium oxide-catalyzed diphenylamine bidirectional stable iodine electrode described in any one of claims 1 to 4 as a positive electrode material, zinc as a negative electrode material, and a zinc salt aqueous solution as an electrolyte.

7. The aqueous zinc ion battery according to claim 6, characterized in that: The zinc salt aqueous solution is zinc sulfate, zinc perchlorate or zinc trifluoromethanesulfonate.

8. Use of the aqueous zinc ion battery according to claim 6 or 7 in improving battery cycle stability.

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