A new negative electrode material for aqueous battery, aqueous battery and preparation method thereof

Abstract

The present invention relates to the technical field of battery materials, and in particular to a novel negative electrode material for aqueous batteries, comprising a novel phenazine-like material, wherein the novel phenazine-like material is pyrazino[2,3-b]pyrazine or quinoxalo[2,3-b]quinoxaline. The novel negative electrode material for aqueous batteries of the present invention is used as a negative electrode material for aqueous batteries, and its specific capacity can reach 905 mAh g ‑1 and 590mAh g ‑1 The specific capacity of the new phenazine-like material is about 100%, which is much higher than that of the phenazine electrode material. It has high specific capacity, good cycle stability and long cycle capacity. The new phenazine-like material for negative electrode active material is highly safe, pollution-free, easy to synthesize, and has abundant raw material resources and low price.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery materials, and in particular relates to a novel negative electrode material for an aqueous battery, an aqueous battery and a preparation method thereof. Background Art

[0002] In recent years, the continuous development of renewable energy has placed higher demands on the performance of energy storage devices. Batteries, as one of the most reliable electrochemical energy storage systems, hold great promise for large-scale energy storage. While lithium-ion batteries, currently in use, offer advantages such as strong discharge capacity, long cycle life, and high capacity density, and are widely used in electric vehicles, smartphones, and laptops, they contain flammable organic solvents, posing significant safety risks.

[0003] Aqueous batteries have attracted widespread attention due to their inexpensive, widely available, and non-toxic electrode materials. The most significant feature of this type of battery is its use of aqueous electrolytes. Compared to batteries using organic electrolytes, aqueous electrolyte ions diffuse more rapidly, thus eliminating the need for thin plates and simplifying the manufacturing process, which helps reduce costs. Aqueous electrolytes also exhibit better ion mobility than organic electrolytes. More importantly, the aqueous electrolyte materials used are non-toxic, offering increased safety and simplifying the recycling of waste batteries. Currently, the development of aqueous battery anode materials is limited by their low energy density and poor stability in aqueous solutions. Therefore, there is a need to develop new aqueous anode materials that are simple, inexpensive, safe, and offer high specific capacity. Summary of the Invention

[0004] The purpose of the present invention is to provide a new negative electrode material for aqueous batteries, aqueous batteries and their preparation methods, so as to overcome the shortcomings and defects of the existing technology.

[0005] To achieve the above objectives, the present invention provides a novel negative electrode material for aqueous batteries, comprising a novel phenazine-like material, wherein the novel phenazine-like material is pyrazino[2,3-b]pyrazine or quinoxalo[2,3-b]quinoxaline, and has the following structure:

[0006]

[0007] The chemical name of structure 1 is pyrazino[2,3-b]pyrazine, and the chemical name of structure 2 is quinoxalo[2,3-b]quinoxaline.

[0008] Preferably, in the novel negative electrode material for aqueous batteries, the synthesis method of pyrazino[2,3-b]pyrazine comprises: reacting 2,3-diaminopyrazine with an aqueous solution of glyoxal, heating to reflux, cooling and filtering, and recrystallizing the filter cake with water to obtain pyrazino[2,3-b]pyrazine; the synthesis reaction is as follows:

[0009]

[0010] Preferably, in the above-mentioned new negative electrode material for aqueous batteries, the reaction solvent is water, the reaction temperature is 70-110°C, and the reaction time is 10-25 min; the molar ratio of 2,3-diaminopyrazine and glyoxal is 1:3.5-4.5, and the mass fraction of the glyoxal aqueous solution is 40%-55%.

[0011] Preferably, in the above-mentioned novel negative electrode material for aqueous batteries, the synthesis method of quinoxalo[2,3-b]quinoxaline comprises the following steps:

[0012] 1) o-phenylenediamine and 2,3-dichloroquinoxaline were heated to reflux, cooled to room temperature, and the reaction solution was poured into a large amount of water; filtered and recrystallized to obtain a yellow solid 5,11-dihydro-5,6,11,12-tetraazonaphthalene;

[0013] 2) reflux heating of 5,11-dihydro-5,6,11,12-tetraazonaphthalene and PbO2, cooling and filtering, and recrystallizing the filter cake from CH3CN to obtain quinoxaline [2,3-b] quinoxaline;

[0014] The synthetic reaction is as follows:

[0015]

[0016] Preferably, in the above-mentioned novel negative electrode material for aqueous batteries, in step 1), the reaction solvent is ethylene glycol, the reaction temperature is 180-210° C., the reaction time is 2-4 h, and the molar ratio of o-phenylenediamine to 2,3-dichloroquinoxaline is 2:1-1.2;

[0017] In the step 2), the reaction solvent is chloroform, the reaction temperature is 50-70° C., the reaction time is 20-30 h, and the molar ratio of 5,11-dihydro-5,6,11,12-tetraazonaphthalene to PbO 2 is 1:14-16.

[0018] The present invention also provides a method for preparing the novel negative electrode material for aqueous batteries, comprising the following steps:

[0019] (1) The novel phenazine-like material is dissolved in a hydrochloric acid solution, a conductive agent is added, and the mixture is stirred at a speed of 1000 rpm for 0.1 to 1 hour. The mixed system is ultrasonically treated for 20 to 40 minutes, and then placed under vacuum conditions and kept still for 20 to 40 minutes. NaOH solution is added to the mixed system at a rate of 0.01 to 0.25 ml / min; the mixture is filtered, washed, and freeze-dried to obtain a nano-phenazine-like / conductive agent composite material;

[0020] (2) grinding the nano-phenazine / conductive agent composite material for 15 to 30 minutes, pressing it between two layers of nickel foam, and then rolling it to obtain a substrate;

[0021] (3) The binder is dropped onto the rolled substrate and dried to obtain a new negative electrode material for aqueous batteries.

[0022] Preferably, in the above-mentioned method for preparing the novel negative electrode material for aqueous batteries, in step (1), the conductive agent is one or more of Super P, carbon nanotubes, and acetylene black having a porous structure;

[0023] The ultrasonic power was 40 kHz;

[0024] The mass ratio of the new phenazine-like material to the conductive agent is 7-9.5:0.5-3;

[0025] The molar ratio of the novel phenazine-like material to hydrochloric acid is 1:200-300;

[0026] The molar ratio of hydrochloric acid to sodium hydroxide is 1:1.2-1.3, and the dropping rate is 0.01-0.25 ml / min. The dropping rate of the sodium hydroxide solution is controlled so that the pyrazino[2,3-b]pyrazine in the hydrochloric acid solution is slowly precipitated and uniformly deposited in the porous structure in nanometer size.

[0027] Preferably, in the above-mentioned method for preparing the novel negative electrode material for aqueous batteries, in the step (2), the roller compaction density is 1.3 to 1.5 g / cm 3 .

[0028] Preferably, in the above-mentioned method for preparing the new negative electrode material for aqueous batteries, in the step (3), the mass ratio of the nano-phenazine / conductive agent composite material to the binder is 90-95:5-10, and the binder is a substance that is stable in an alkaline environment and does not react with the electrode material.

[0029] An aqueous battery comprises a positive electrode, a negative electrode, a separator and an electrolyte, wherein the negative electrode is a novel negative electrode material for an aqueous battery prepared by the above-mentioned preparation method.

[0030] Preferably, in the above aqueous battery, the positive electrode material is nickel hydroxide or activated carbon, the separator is made of hard glass fiber, and the electrolyte is sodium hydroxide solution or potassium hydroxide solution.

[0031] Preferably, in the above aqueous battery, the molar concentration of the electrolyte is 5 to 7 mol / L.

[0032] Preferably, in the above aqueous battery, the assembly method is that the negative electrode material is coated with a diaphragm in the middle, and the upper and lower layers are fixed with positive electrodes to form a sandwich-type electrode group.

[0033] Compared with the existing technology, the present invention has the following beneficial effects:

[0034] 1. The novel negative electrode material for aqueous batteries of the present invention can be used as the negative electrode material of aqueous batteries, and its specific capacity can reach 905mAh g -1 and 590mAh g -1 The specific capacity of the new phenazine-like material is about 100%, which is much higher than that of the phenazine electrode material. It has high specific capacity, good cycle stability and long cycle capacity. The new phenazine-like material for negative electrode active material is highly safe, pollution-free, easy to synthesize, and has abundant raw material resources and low price.

[0035] 2. In the preparation method of the new negative electrode material for aqueous batteries of the present invention, the roller pressing method can make the new phenazine material / conductive agent composite material and foam nickel very firmly bonded, effectively avoiding the powder loss phenomenon; the preparation process is simple, low cost and low energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the H NMR spectrum of pyrazine[2,3-b]pyrazine prepared in Example 1 of the present invention;

[0037] Figure 2 This is the H NMR spectrum of quinoxalino[2,3-b]quinoxaline prepared in Example 2 of the present invention;

[0038] Figure 3 Cyclic voltammograms of the negative electrode materials of Example 3, Example 5 and Comparative Example 1 of the present invention at a scan rate of 0.01 v / s;

[0039] Figure 4 The cyclic voltammogram of the negative electrode material of Comparative Example 1 of the present invention scanned 5 times at a scan rate of 0.01 v / s;

[0040] Figure 5 The cyclic voltammogram of the negative electrode material of Example 5 of the present invention scanned 5 times at a scan rate of 0.01 v / s;

[0041] Figure 6 The cyclic voltammogram of the negative electrode material of Example 3 of the present invention at scan rates of 0.01 v / s and 0.005 v / s;

[0042] Figure 7 The battery cycle capacity graphs of Example 4, Example 6 and Comparative Example 2 of the present invention are shown. DETAILED DESCRIPTION

[0043] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0044] Example 1

[0045] 1.35g of glyoxal was added to water to prepare a 50wt% glyoxal aqueous solution. 0.7g of 2,3-diaminopyrazine was added to the glyoxal aqueous solution, refluxed at 105°C for 15 minutes, then cooled and filtered. The filter cake was recrystallized with water to obtain a yellow solid pyrazine [2,3-b] pyrazine. The H NMR spectrum of the prepared pyrazine [2,3-b] pyrazine is as follows: Figure 1 shown.

[0046] Example 2

[0047] 5.50 g of o-phenylenediamine and 5.00 g of 2,3-dichloroquinoxaline were heated under reflux at 200°C in ethylene glycol (30 ml) for 2 hours. After cooling to room temperature, the mixture was filtered. The filter cake was recrystallized from ethanol and dried under vacuum to obtain 5,11-dihydro-5,6,11,12-tetraazonaphthalene as a yellow solid.

[0048] 1.0 g of 5,11-dihydro-5,6,11,12-tetraazonaphthalene and 15.0 g of PbO2 were refluxed at 60°C for 24 hours in 50 ml of CHCl3. The mixture was cooled to room temperature and filtered. The filter cake was recrystallized from CH3CN and dried under vacuum to obtain a light red solid quinoxalino[2,3-b]quinoxaline. The prepared quinoxalino[2,3-b]quinoxaline is as follows Figure 2 shown.

[0049] Example 3

[0050] A novel negative electrode material for aqueous batteries, comprising a novel phenazine-like material and a conductive agent, wherein the conductive agent is Super P, and the novel phenazine-like material is pyrazino[2,3-b]pyrazine synthesized in Example 1, and has the following structural formula:

[0051]

[0052] A method for preparing a new negative electrode material for an aqueous battery comprises the following steps:

[0053] (1) 0.96 g of pyrazino[2,3-b]pyrazine was dissolved in 365 mL of 5 mol / L hydrochloric acid solution under magnetic stirring, and 0.11 g of Super P was added. The mixture was stirred at 1000 rpm for 10 min to disperse the Super P evenly in the solution. Then, the mixture was ultrasonically treated at a power of 40 kHz for 30 min and then placed under vacuum and kept for 30 min to allow the pyrazino[2,3-b]pyrazine solution to fully penetrate into the pores of Super P. In order to allow the pyrazino[2,3-b]pyrazine in the hydrochloric acid solution to slowly precipitate and uniformly deposit on the surface of the porous Super P at a nanometer size, a peristaltic pump was used at a speed of 0.2 mL min -1456 mL of 5 mol / L NaOH solution was slowly added to the above mixed system at a speed of 100 ℃; after filtration, it was fully washed with a large amount of deionized water and freeze-dried for 24 hours to obtain a nano-pyrazino[2,3-b]pyrazine / Super P composite material;

[0054] (2) The nano-pyrazino[2,3-b]pyrazine / SuperP composite powder was ground in a mortar for 20 min, and the composite powder was filled between two layers of nickel foam at a pressure of 1.3 g / cm 3 Roll pressing is performed to ensure that the pyrazino[2,3-b]pyrazine / Super P composite material is firmly bonded to the nickel foam;

[0055] (3) 0.09 g of 60 wt% polytetrafluoroethylene concentrated dispersion binder was dropped onto the rolled electrode, and then dried to obtain a pyrazino[2,3-b]pyrazine / Super P negative electrode.

[0056] Example 4

[0057] Nickel hydroxide was used as the positive electrode material. The middle pyrazino[2,3-b]pyrazine / Super P negative electrode sheet (prepared in Example 3) was wrapped with rigid fiberglass. The upper and lower layers were clamped with nickel hydroxide positive electrode sheets, and nickel tabs were welded to each layer. The outer layer was partially sealed with aluminum-plastic film. A sufficient amount of 6 mol / L sodium hydroxide electrolyte was added to prepare a pyrazino[2,3-b]pyrazine / nickel battery. After standing for 24 hours, performance testing was conducted.

[0058] Example 5

[0059] A novel negative electrode material for aqueous batteries, comprising a novel phenazine-like material and a conductive agent, wherein the conductive agent is Super P, and the novel phenazine-like material is quinoxaline [2,3-b]quinoxaline (Structure 2) synthesized in Example 2, having the following structural formula:

[0060]

[0061] The preparation steps and feeding ratios were the same as those in Example 3, except that the raw material was replaced with quinoxaline [2,3-b] quinoxaline to obtain a quinoxaline [2,3-b] quinoxaline / Super P negative electrode sheet.

[0062] Example 6

[0063] The preparation steps were the same as those in Example 4, except that the negative electrode was replaced with a quinoxaline [2,3-b] quinoxaline / Super P negative electrode to prepare a quinoxaline [2,3-b] quinoxaline / nickel battery.

[0064] Comparative Example 1

[0065] Phenazine was used to replace pyrazino[2,3-b]pyrazine, and the preparation steps and feeding ratio were the same as those in Example 3 to obtain a phenazine / Super P negative electrode sheet.

[0066] Comparative Example 2

[0067] The preparation steps were the same as those in Example 4, except that the negative electrode was replaced with a phenazine / Super P negative electrode sheet to prepare a phenazine / nickel battery.

[0068] (1) Cyclic voltammetry characterization

[0069] The performance of the negative electrode sheets prepared in Example 3, Example 5 and Comparative Example 1 was tested. A three-electrode system was used, with pyrazino[2,3-b]pyrazine / Super P negative electrode sheet, quinoxalo[2,3-b]quinoxaline / Super P negative electrode sheet and phenazine / Super P negative electrode sheet as working electrodes, nickel hydroxide as counter electrode, calomel electrode as reference electrode, and 6 mol / L alkaline sodium hydroxide as electrolyte. Cyclic voltammetry test was performed. The results are shown in FIG. Figures 3 to 6 . Figure 3 、 4 and 5 are cyclic voltammograms at a scan rate of 0.01 v / s.

[0070] Figure 3 The cyclic voltammograms of the negative electrode materials of Examples 3, 5, and Comparative Example 1 at a scan rate of 0.01 v / s show that the redox currents of Examples 3 and 5 are lower than those of Comparative Example 1, indicating that the pyrazino[2,3-b]pyrazine / Super P composites and the quinoxalo[2,3-b]quinoxaline / Super P composites have better reversibility. The redox potential differences of Examples 3 and 5 are lower than those of the phenazine / Super P composite, indicating that the pyrazino[2,3-b]pyrazine / Super P composites and the quinoxalo[2,3-b]quinoxaline / Super P composites have lower polarization.

[0071] Figure 4 and Figure 5 The cyclic voltammograms of the negative electrode materials of Comparative Example 1 and Example 5 of the present invention were obtained after five cycles at a scan rate of 0.01 v / s. The redox potentials of the cyclic voltammogram for Comparative Example 1 were -0.5 V and -1.2 V, respectively, and remained unchanged after five cycles. The cyclic voltammogram for Example 5 exhibited two reduction peaks at -0.5 V, indicating the presence of two electrochemical cathode reactions. After the fifth cycle, the cyclic voltammograms remained unchanged from the first cycle, demonstrating that both quinoxalo[2,3-b]quinoxaline / Super P and phenazine / Super P exhibited good cycling stability.

[0072] Figure 6The cyclic voltammograms of the negative electrode material of Example 3 of the present invention at scan rates of 0.01 v / s and 0.005 v / s show that the cyclic voltammogram of the negative electrode material of Example 3 shows only one oxidation peak at -0.5 v. When the scan rate is reduced, the peak current decreases, and no reduction peak is shown at -0.5 v. This may be because the material itself is slightly dissolved in the alkaline electrolyte, resulting in the disappearance of the reduction peak and no change in the peak potential, indicating that the pyrazino[2,3-b]pyrazine / Super P material has certain cyclic reversibility.

[0073] (2) Battery performance characterization

[0074] At a constant temperature of 25 degrees, the pyrazino[2,3-b]pyrazine / nickel battery (Example 4), quinoxalo[2,3-b]quinoxaline / nickel battery (Example 6) and phenazine / nickel battery (Comparative Example 1) were activated at a low rate of 0.1C for 5 weeks, and then charged and discharged at a constant current rate of 0.5C for 350 cycles to obtain the battery cycle capacity spectrum (see Figure 7 ).

[0075] from Figure 7 It can be seen that the initial discharge gram capacities of the pyrazino[2,3-b]pyrazine / nickel battery, quinoxaline[2,3-b]quinoxaline / nickel battery and phenazine / nickel battery are 889 mAh / g, 570 mAh / g and 290 mAh / g, respectively. The initial discharge gram capacities of the pyrazino[2,3-b]pyrazine / nickel battery and quinoxaline[2,3-b]quinoxaline / nickel battery are about 3 times and 2 times that of the phenazine / nickel battery, respectively. As the number of cycles increases, the capacity of the pyrazino[2,3-b]pyrazine / nickel battery decreases, indicating that pyrazino[2,3-b]pyrazine has slight solubility in alkaline aqueous solution, resulting in partial capacity loss. When the cycle reaches 350 weeks, the capacity retention rates of the pyrazino[2,3-b]pyrazine / nickel battery and quinoxaline[2,3-b]quinoxaline / nickel battery are around 87% and 95%, respectively, indicating that pyrazino[2,3-b]pyrazine and quinoxaline[2,3-b]quinoxaline as negative electrode materials for aqueous batteries have long-term cycling capabilities.

[0076] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. An aqueous battery, characterized in that: The invention comprises a positive electrode, a negative electrode, a separator and an electrolyte. The positive electrode material is nickel hydroxide, the electrolyte is a sodium hydroxide solution or a potassium hydroxide solution, and the negative electrode comprises a novel phenazine-like material. The novel phenazine-like material has the following structure 1 or structure 2: Structure 1 Structure 2: Structure 1 is pyrazino[2,3-b]pyrazine, and Structure 2 is quinoxalo[2,3-b]quinoxaline.

2. The aqueous battery according to claim 1, wherein The diaphragm is made of hard glass fiber, the electrolyte is a sodium hydroxide solution or a potassium hydroxide solution, and the molar concentration of the electrolyte is 5-7 mol / L.

3. The aqueous battery according to claim 1, wherein The assembly method is to use a diaphragm to cover the negative electrode material in the middle, and the upper and lower layers are fixed with positive electrodes to form a sandwich-type electrode group.

4. A method for preparing an aqueous battery according to any one of claims 1 to 3, characterized in that: The method for preparing the negative electrode material comprises the following steps: (1) The novel phenazine-like material was dissolved in a hydrochloric acid solution, a conductive agent was added, and the mixture was vigorously stirred for 0.1 to 1 hour. The mixed system was ultrasonically treated for 20 to 40 minutes, and then kept under vacuum conditions for 20 to 40 minutes. NaOH solution was added to the mixed system at a certain drop rate; the mixture was filtered, washed, and freeze-dried to obtain a nano-phenazine-like / conductive agent composite material; (2) Grinding the nano-phenazine / conductive agent composite material for 15-30 min, pressing it between two layers of nickel foam, and then rolling it to obtain a substrate; (3) The binder is dropped onto the rolled substrate and dried to obtain a new negative electrode material for aqueous batteries.

5. The method for preparing an aqueous battery according to claim 4, wherein: In the step (1), the conductive agent is one or more of Super P with a porous structure, carbon nanotubes, and acetylene black; the mass ratio of the new phenazine-like material to the conductive agent is 7-9.5:0.5-3; the molar ratio of the new phenazine-like material to hydrochloric acid is 1:200-300; the molar ratio of hydrochloric acid to sodium hydroxide is 1:1.2-1.3, and the dripping rate is 0.01-0.25 ml / min; In the step (2), the roller compaction density is 1.3~1.5g / cm 3 ; In the step (3), the mass ratio of the nano-phenazine / conductive agent composite material to the binder is 90-95:5-10, and the binder is a substance that is stable in an alkaline environment and does not react with the electrode material.

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