Organic active substance and preparation method and negative electrode electrolyte based on organic active substance

Abstract

The invention relates to the technical field of aqueous organic flow battery electrolytes, and discloses an organic active substance, a preparation method based on the organic active substance and a negative electrode electrolyte.The preparation method of the organic active substance comprises the steps that a substance A, a substance B and a Pd catalyst are dispersed in an organic solvent, stirring reaction is conducted, a mixed solution is obtained, solid-liquid separation and drying are conducted, and the organic active substance is obtained. And dispersing the obtained precipitate in concentrated sulfuric acid, carrying out reflux reaction, cooling after the reaction is finished, centrifuging, and collecting the solid precipitate to obtain the organic active substance. According to the active organic matter prepared through the method, in the battery reaction process, a single molecule can transfer four electrons, and the energy density of electrolyte can be effectively improved. In addition, sulfonation can also effectively improve the solubility of the active organic matter in the aqueous solvent, and the energy density of the electrolyte is further improved.

Description

Technical Field

[0001] This application relates to the technical field of electrolytes for aqueous organic flow batteries, and particularly to an organic active substance, a preparation method based on the same, and a negative electrode electrolyte. Background Art

[0002] Flow batteries are a type of energy storage system with high cycle efficiency and adjustable properties, having broad prospects. Aqueous organic flow batteries use water-based electrolytes, eliminating the risk of fire or explosion. Compared with common all-vanadium flow batteries, organic active substances can be mass-produced through simple chemical synthesis and do not rely on rare metals. The electrolyte is based on elements such as carbon, hydrogen, oxygen, and nitrogen, and the synthesis process is green and environmentally friendly and recyclable, with excellent characteristics such as low cost, diverse types, and strong controllability. However, the active substances of aqueous organic flow batteries have problems of poor solubility and low energy efficiency in aqueous solvents, which directly affect the efficiency and capacity of aqueous organic flow batteries, and further increase the construction cost and usage cost. Summary of the Invention

[0003] The purpose of this application is to provide an organic active substance, a preparation method based on the same, and a negative electrode electrolyte. By adjusting the structure of the organic active substance, the number of electrons transferred by a single molecule of the active substance during oxidation-reduction is increased; by performing functional group modification on the organic active substance, the solubility is improved, thereby solving the problems of poor solubility and low energy efficiency of the organic active substance in aqueous solvents.

[0004] To achieve the above purpose, this application provides the following technical solutions: In the first aspect, an embodiment of this application provides an organic active substance, and the structure of the organic active substance is: .

[0005] In the second aspect, an embodiment of this application provides a preparation method of the above-mentioned organic active substance. The preparation method includes: dispersing substance A, substance B, and a Pd catalyst in an organic solvent, stirring and reacting to obtain a mixed solution, performing solid-liquid separation, drying, dispersing the obtained precipitate in concentrated sulfuric acid, refluxing and reacting, reducing the temperature after the reaction ends, centrifuging, and collecting the solid precipitate to obtain the organic active substance (DPZ). The substance generated by the reaction of substance A and substance B contains four phenazine N atoms. During the charge-discharge oxidation-reduction reaction process of the battery, a single molecule can provide the transfer of 4 electrons. The reaction process is as follows:

[0006] Under the condition of equal-concentration electrolyte, it can effectively improve the energy density of the electrolyte. Or under the condition of equal energy density, it can maintain the electrolyte at a low concentration, promote the mass transfer rate during the redox reaction of the battery, reduce concentration polarization, and improve the efficiency of the battery. The introduction of the sulfonic acid group belongs to an electrophilic substitution reaction. In the benzene ring part of phenazine, especially the carbon atoms at the para position, the electron-withdrawing effect of the nitrogen atom is weak, which is more conducive to the growth of the sulfonic acid group. Through the action of concentrated sulfuric acid, the sulfonic acid group can grow on the organic molecule, and the sulfonic acid group contains three highly polar oxygen atoms (two double-bonded oxygens and one single-bonded oxygen), and these oxygen atoms can form multiple hydrogen bonds with water molecules, which can effectively improve the solubility of the active organic matter in the aqueous solvent.

[0007] Preferably, the basic structural formula of the substance A contains a benzene ring, a nitro group, and other substituents. The nitro group and other substituents are in the ortho position and are directly connected to the benzene ring, and it is selected from one of 2-bromonitrobenzene, 2-nitrobenzonitrile, o-nitrophenol, 1-fluoro-2-nitrobenzene, 1-iodo-2-nitrobenzene, 2-nitrobenzeneacetic acid; the substance B is a benzidine substance, selected from 3,3'-diaminobenzidine, 3,3'-dihydroxybenzidine, 3,3'-methoxybenzidine; the organic solvent is one of acetone, benzene, N,N-dimethylformamide.

[0008] Preferably, the mass ratio of the substance A, the substance B, the Pd catalyst, and the organic solvent is 1:(0.5~1):(0.01~0.03):(10~50).

[0009] Preferably, the mass ratio of the precipitate to the concentrated sulfuric acid is 1:(20~100); the temperature of the reflux reaction is 70~100 °C, and the time is 12~24 h.

[0010] In a third aspect, an embodiment of the present application provides a negative electrode electrolyte, and the negative electrode electrolyte is composed of the above-mentioned organic active substance or the organic active substance prepared by the above-mentioned preparation method.

[0011] Preferably, the negative electrode electrolyte further includes an alkali solution and a composite additive.

[0012] Preferably, the concentration of the organic active substance in the negative electrode electrolyte is 0.1~1 mol / L.

[0013] Preferably, the alkali solution is one of a potassium hydroxide solution and a sodium hydroxide solution, and the concentration of the alkali solution in the negative electrode electrolyte is 0.5~3 mol / L.

[0014] Preferably, the composite additive is composed of an inorganic additive and an organic additive in a mass ratio of 1:(0.05~0.5). The inorganic additive is one of sodium sulfite and potassium sulfite, and the organic additive is polyvinylpyrrolidone with a K value less than 60. The content of the composite additive in the negative electrode electrolyte is 1~10 g / L. Under strong alkaline conditions, sodium sulfite or potassium sulfite can release reducing sulfur dioxide gas, which can effectively prevent the negative electrode electrolyte from being oxidized and improve the energy efficiency and capacity retention rate of the battery. As a water-soluble polymer compound, polyvinylpyrrolidone has film-forming property, adhesiveness, hygroscopicity and solubilization effect, which can improve the mass transfer and dispersion of the electrolyte, and thus improve the efficiency of the battery. However, it should be noted that higher molecular weight and concentration of polyvinylpyrrolidone will increase the viscosity of the electrolyte and have an adverse effect on the battery performance. Therefore, its molecular weight and concentration need to be controlled. Brief Description of the Drawings

[0015] Figure 1 Schematic diagram of a preparation method of a negative electrode electrolyte according to the present application. Detailed Embodiments

[0016] To make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the scope of the present application. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present application.

[0017] As Figure 1As shown, a negative electrode electrolyte is composed of an organic active substance with a concentration of 0.1 - 1 mol / L, an alkali solution with a concentration of 0.5 - 3 mol / L, and a composite additive with a concentration of 1 - 10 g / L. The preparation method of the organic active substance is as follows: Substance A, Substance B, a Pd catalyst (it is also possible to have a Pd catalyst and 1,1'-binaphthalene-2,2'-bis(diphenylphosphine) coexist), and an organic solvent are dispersed in the organic solvent according to a mass ratio of 1:(0.5 - 1):(0.01 - 0.03):(10 - 50), stirred and reacted to obtain a mixed solution, then solid-liquid separated and dried. The obtained precipitate and concentrated sulfuric acid are dispersed according to a mass ratio of 1:(20 - 100), and refluxed at a temperature of 70 - 100 °C for 12 - 24 h. After the reaction, the temperature is lowered, centrifuged, and the solid precipitate is collected to obtain the organic active substance; the basic structural formula of Substance A contains a benzene ring, a nitro group, and other substituents, and the nitro group and other substituents are in the ortho position and directly connected to the benzene ring; Substance B is a benzidine-based substance. The alkali solution is one of potassium hydroxide solution and sodium hydroxide solution. The composite additive is composed of an inorganic additive and an organic additive according to a mass ratio of 1:(0.05 - 0.5). The inorganic additive is one of sodium sulfite and potassium sulfite, and the organic additive is polyvinylpyrrolidone with a K value less than 60. Substance A is one of 2-bromonitrobenzene, 2-nitrobenzonitrile, o-nitrophenol, 1-fluoro-2-nitrobenzene, 1-iodo-2-nitrobenzene, and 2-nitrobenzeneacetic acid. Substance B is 3,3'-diaminobenzidine, 3,3'-dihydroxybenzidine, or 3,3'-methoxybenzidine. The organic solvent is one of acetone, benzene, and N,N-dimethylformamide.

[0018] Example 1: The negative electrode electrolyte in this example is prepared according to the following scheme A negative electrode electrolyte is composed of an organic active substance with a concentration of 0.1 mol / L, a potassium hydroxide solution with a concentration of 0.5 mol / L, and a composite additive composed of sodium sulfite and polyvinylpyrrolidone according to a mass ratio of 1:0.05 with a concentration of 1 g / L. The solution formed by the three is the negative electrode electrolyte in this example.

[0019] The preparation method of the organic active substance used in the negative electrode electrolyte in this example is as follows: 2-bromonitrobenzene, 3,3'-diaminobenzidine, a Pd catalyst, and acetone are dispersed in the organic solvent according to a mass ratio of 1:0.5:0.01:10, stirred and reacted to obtain a mixed solution, then solid-liquid separated and dried. The obtained precipitate and concentrated sulfuric acid are dispersed according to a mass ratio of 1:20, and refluxed at a temperature of 100 °C for 12 h. After the reaction, the temperature is lowered, centrifuged, and the solid precipitate is collected to obtain the organic active substance.

[0020] Example 2: The negative electrode electrolyte in this example is prepared according to the following scheme A negative electrode electrolyte is a solution formed by an organic active substance with a concentration of 1 mol / L, a sodium hydroxide solution with a concentration of 3 mol / L, and a composite additive composed of potassium sulfite and polyvinylpyrrolidone with a mass ratio of 1:0.5 and a concentration of 10 g / L. The solution formed by these three components is the negative electrode electrolyte of this embodiment.

[0021] The preparation method of the organic active substance used in the negative electrode electrolyte of this embodiment is as follows: 2-nitrobenzonitrile, 3,3'-dihydroxybenzidine, a Pd catalyst, and benzene are dispersed in an organic solvent in a mass ratio of 1:1:0.03:50, stirred and reacted to obtain a mixed solution, followed by solid-liquid separation and drying. The obtained precipitate and concentrated sulfuric acid are dispersed in a mass ratio of 1:100 and refluxed at 70 °C for 24 h. After the reaction, the temperature is lowered, centrifuged, and the solid precipitate is collected to obtain the organic active substance.

[0022] Example 3: The negative electrode electrolyte of this example is prepared according to the following scheme A negative electrode electrolyte is a solution formed by an organic active substance with a concentration of 0.3 mol / L, a potassium hydroxide solution with a concentration of 1 mol / L, and a composite additive composed of sodium sulfite and polyvinylpyrrolidone with a mass ratio of 1:0.1 and a concentration of 50 g / L. The solution formed by these three components is the negative electrode electrolyte of this embodiment.

[0023] The preparation method of the organic active substance used in the negative electrode electrolyte of this embodiment is as follows: o-nitrophenol, 3,3'-methoxybenzidine, a Pd catalyst, and N,N-dimethylformamide are dispersed in an organic solvent in a mass ratio of 1:0.7:0.02:20, stirred and reacted to obtain a mixed solution, followed by solid-liquid separation and drying. The obtained precipitate and concentrated sulfuric acid are dispersed in a mass ratio of 1:60 and refluxed at 80 °C for 15 h. After the reaction, the temperature is lowered, centrifuged, and the solid precipitate is collected to obtain the organic active substance.

[0024] Example 4: The negative electrode electrolyte of this example is prepared according to the following scheme A negative electrode electrolyte is a solution formed by an organic active substance with a concentration of 0.5 mol / L, a potassium hydroxide solution with a concentration of 2 mol / L, and a composite additive composed of sodium sulfite and polyvinylpyrrolidone with a mass ratio of 1:0.3 and a concentration of 8 g / L. The solution formed by these three components is the negative electrode electrolyte of this embodiment.

[0025] The preparation method of the organic active substance used in the negative electrode electrolyte of this embodiment is as follows: 1-fluoro-2-nitrobenzene, 3,3'-diaminobenzidine, Pd catalyst and N,N-dimethylformamide are dispersed in an organic solvent according to a mass ratio of 1:0.8:0.03:40, and stirred and reacted to obtain a mixed solution. After solid-liquid separation and drying, the obtained precipitate and concentrated sulfuric acid are dispersed at a mass ratio of 1:70, and refluxed at 80 °C for 20 h. After the reaction, the temperature is lowered, centrifuged, and the solid precipitate is collected to obtain the organic active substance.

[0026] Example 5: The negative electrode electrolyte of this example is prepared according to the following scheme A negative electrode electrolyte is a solution formed by an organic active substance with a concentration of 0.8 mol / L, a potassium hydroxide solution with a concentration of 2 mol / L, and a composite additive composed of potassium sulfite and polyvinylpyrrolidone with a mass ratio of 1:0.4 and a concentration of 7 g / L. The solution is the negative electrode electrolyte of this example.

[0027] The preparation method of the organic active substance used in the negative electrode electrolyte of this embodiment is as follows: 1-iodo-2-nitrobenzene, 3,3'-dihydroxybenzidine, Pd catalyst and benzene are dispersed in an organic solvent according to a mass ratio of 1:0.7:0.03:35, and stirred and reacted to obtain a mixed solution. After solid-liquid separation and drying, the obtained precipitate and concentrated sulfuric acid are dispersed at a mass ratio of 1:40, and refluxed at 80 °C for 22 h. After the reaction, the temperature is lowered, centrifuged, and the solid precipitate is collected to obtain the organic active substance.

[0028] Example 6: The negative electrode electrolyte of this example is prepared according to the following scheme A negative electrode electrolyte is a solution formed by an organic active substance with a concentration of 1 mol / L, a potassium hydroxide solution with a concentration of 2 mol / L, and a composite additive composed of sodium sulfite and polyvinylpyrrolidone with a mass ratio of 1:0.5 and a concentration of 4 g / L. The solution is the negative electrode electrolyte of this example.

[0029] The preparation method of the organic active substance used in the negative electrode electrolyte of this embodiment is as follows: 2-nitrobenzeneacetic acid, 3,3'-diaminobenzidine, Pd catalyst, 1,1'-binaphthalene-2,2'-bis(diphenylphosphine) and N,N-dimethylformamide are dispersed in an organic solvent according to a mass ratio of 1:0.5:0.02:0.02:30, and stirred and reacted to obtain a mixed solution. After solid-liquid separation and drying, the obtained precipitate and concentrated sulfuric acid are dispersed at a mass ratio of 1:80, and refluxed at 90 °C for 24 h. After the reaction, the temperature is lowered, centrifuged, and the solid precipitate is collected to obtain the organic active substance.

[0030] Comparative Example 1: The difference between the preparation process of the negative electrode electrolyte in this comparative example and that in Example 1 is that phenazine is used as the organic active substance. A negative electrode electrolyte is a solution formed by 0.1 mol / L phenazine, 0.5 mol / L potassium hydroxide solution, and 1 g / L composite additive composed of sodium sulfite and polyvinylpyrrolidone in a mass ratio of 1:0.05.

[0031] Comparative Example 2: The difference between the preparation process of the negative electrode electrolyte in this comparative example and that in Example 1 is that the composite additive is not added. A negative electrode electrolyte is a solution formed by 0.1 mol / L organic active substance and 0.5 mol / L potassium hydroxide solution.

[0032] The preparation method of the organic active substance used in the negative electrode electrolyte of this comparative example is as follows: 2-bromonitrobenzene, 3,3'-diaminobenzidine, Pd catalyst and acetone are dispersed in an organic solvent in a mass ratio of 1:0.5:0.01:10, stirred and reacted to obtain a mixed solution, solid-liquid separated, dried, the obtained precipitate and concentrated sulfuric acid are dispersed in a mass ratio of 1:20, refluxed at 100 °C for 12 h, the temperature is reduced after the reaction, centrifuged, and the solid precipitate is collected to obtain the organic active substance.

[0033] Comparative Example 3: The difference between the preparation process of the negative electrode electrolyte in this comparative example and that in Example 1 is that the composite additive does not contain an organic additive. A negative electrode electrolyte is a solution formed by 0.1 mol / L organic active substance, 0.5 mol / L potassium hydroxide solution, and 1 g / L sodium sulfite.

[0034] The preparation method of the organic active substance used in the negative electrode electrolyte of this comparative example is as follows: 2-bromonitrobenzene, 3,3'-diaminobenzidine, Pd catalyst and acetone are dispersed in an organic solvent in a mass ratio of 1:0.5:0.01:10, stirred and reacted to obtain a mixed solution, solid-liquid separated, dried, the obtained precipitate and concentrated sulfuric acid are dispersed in a mass ratio of 1:20, refluxed at 100 °C for 12 h, the temperature is reduced after the reaction, centrifuged, and the solid precipitate is collected to obtain the organic active substance.

[0035] Comparative Example 4: The difference between the preparation process of the negative electrode electrolyte in this comparative example and that in Example 1 is that the composite additive does not contain an inorganic additive. A negative electrode electrolyte is a solution formed by 0.1 mol / L organic active substance, 0.5 mol / L potassium hydroxide solution, and 0.05 g / L polyvinylpyrrolidone.

[0036] The preparation method of the organic active substance used in the negative electrode electrolyte of this comparative example is as follows: 2-bromonitrobenzene, 3,3'-diaminobenzidine, Pd catalyst and acetone are dispersed in an organic solvent at a mass ratio of 1:0.5:0.01:10, stirred for reaction to obtain a mixed solution, solid-liquid separation, drying, and dispersing the obtained precipitate and concentrated sulfuric acid at a mass ratio of 1:20, reflux at 100°C for reaction for 12 hours, and after the reaction is completed, the temperature is lowered, centrifuged, and the solid precipitate is collected to obtain the organic active substance.

[0037] Comparative Example 5: The difference between the preparation process of the organic active material used in the negative electrode electrolyte of this comparative example and that of Example 1 is that concentrated sulfuric acid is not used to treat the precipitate. A negative electrode electrolyte is composed of an organic active material with a concentration of 0.1 mol / L, a potassium hydroxide solution with a concentration of 0.5 mol / L, and a composite additive with a concentration of 1 g / L composed of sodium sulfite and polyvinyl pyrrolidone in a mass ratio of 1:0.05. The solution formed by the three is the negative electrode electrolyte of this comparative example.

[0038] The preparation method of the organic active substance in the negative electrode electrolyte of this comparative example is as follows: 2-bromonitrobenzene, 3,3'-diaminobenzidine, Pd catalyst and acetone are dispersed in an organic solvent in a mass ratio of 1:0.5:0.01:10, stirred for reaction to obtain a mixed solution, solid-liquid separation, and drying to obtain a precipitate, which is the organic active substance of this comparative example.

[0039] Comparative Example 6: All-vanadium liquid flow battery is used as a control.

[0040] Saturation concentration test: The organic active substances prepared in Examples 1 to 6 and Comparative Examples 1 to 6 were added into 100 mL of 1 mol / L sodium hydroxide solution at a constant temperature of 25°C in an amount of 0.01 mol each time (the corresponding molar amount was calculated based on the weight of the precipitate not treated with concentrated sulfuric acid), and the mixture was fully stirred and dissolved until saturated, and the saturation concentration of the organic active substances was tested.

[0041] Battery efficiency test: Using the negative electrode electrolyte prepared in Examples 1 to 6 and Comparative Examples 1 to 6 as the negative electrode and controlling the theoretical capacity of the active substance to be consistent, using 0.3 mol / L potassium ferrocyanide as the positive electrode, charging and discharging were carried out under the same operating conditions, and the coulombic efficiency, energy efficiency, voltage efficiency, maximum discharge capacity and capacity retention rate of the battery were tested.

[0042] The test results are shown in Table 1: Table 1 Summary of test results Test Index Saturation Concentration (mol / L) Coulombic Efficiency (%) Energy Efficiency (%) Voltage Efficiency (%) Capacity Retention Rate after 500 Cycles (%) Example 1 1.57 99.97 82.32 82.34 98% Example 2 1.53 99.99 81.24 81.24 96% Example 3 1.41 99.98 82.11 82.12 99% Example 4 1.48 99.96 82.20 82.23 99% Example 5 1.55 99.99 81.74 81.75 98% Example 6 1.62 99.98 81.42 81.44 96% Comparative Example 1 0.02 - - - - Comparative Example 2 1.56 98.66 79.31 80.39 83% Comparative Example 3 1.52 98.92 80.74 81.62 92% Comparative Example 4 1.58 99.08 80.85 81.60 88% Comparative Example 5 0.03 - - - - Comparative Example 6 - 96.85 83.72 86.49 68% Note: (1) Comparative Examples 1 and 5 were not able to charge and discharge normally due to low concentrations, and no battery data was collected; (2) The all-vanadium redox flow battery in Comparative Example 6 was an acidic aqueous solution, and the conditions could not be kept consistent, so the solubility test was not carried out.

[0043] It can be seen from the saturation concentration test results in Table 1 that the solubility of the active organic matter prepared by the method of the present application is significantly better than that of pyrazine of the same type. This is mainly because the growth of sulfonic acid groups in the molecular structure improves the water solubility of the active organic matter. In addition, it can be seen from Comparative Examples 2-4 that as the degree of sulfonation increases, the solubility of the active organic matter also gradually increases. It can be seen from the efficiency results in Table 1 that as the concentration of the negative electrolyte increases, the energy efficiency and voltage efficiency decrease. Therefore, under the condition of equal energy density, if the negative electrolyte can be maintained at a low concentration, the mass transfer rate in the redox reaction process of the battery can be effectively promoted, the concentration polarization can be reduced, and the efficiency of the battery can be improved. At the same time, as a water-soluble polymer compound, polyvinylpyrrolidone has film-forming property, adhesiveness, hygroscopicity and solubilization effect, and can improve the mass transfer and dispersion of the negative electrolyte, thereby improving the efficiency of the battery. In addition, it can be seen from the capacity retention results in Table 1 that the addition of the composite additive can effectively improve the capacity retention of the battery. This is mainly because under strong alkaline conditions, sodium sulfite or potassium sulfite can release reducing sulfur dioxide gas, and these gases can effectively prevent the negative electrolyte from being oxidized and improve the energy efficiency and capacity retention of the battery.

[0044] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements or improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An organic active substance, characterized in that, The structure of the organic active substance is as follows: 。 2. The preparation method of the organic active substance according to claim 1, characterized in that, The preparation method includes: dispersing substance A, substance B, and a Pd catalyst in an organic solvent, stirring and reacting to obtain a mixed solution, performing solid-liquid separation, drying, dispersing the obtained precipitate in concentrated sulfuric acid, refluxing and reacting, lowering the temperature after the reaction is completed, centrifuging, and collecting the solid precipitate to obtain the organic active substance.

3. The preparation method according to claim 2, characterized in that, Substance A is one of 2-bromonitrobenzene, 2-nitrobenzonitrile, o-nitrophenol, 1-fluoro-2-nitrobenzene, 1-iodo-2-nitrobenzene, 2-nitrobenzeneacetic acid; substance B is 3,3'-diaminobenzidine, 3,3'-dihydroxybenzidine, 3,3'-methoxybenzidine; the organic solvent is one of acetone, benzene, N,N-dimethylformamide.

4. The preparation method according to claim 2, characterized in that, The mass ratio of substance A, substance B, the Pd catalyst, and the organic solvent is 1:(0.5~1):(0.01~0.03):(10~50).

5. The preparation method according to claim 2, wherein The mass ratio of the precipitate to concentrated sulfuric acid is 1:(20~100); the temperature of the reflux reaction is 70~100 °C, and the time is 12~24 h.

6. A negative electrode electrolyte, characterized in that, The negative electrode electrolyte includes the organic active substance described in claim 1 or the organic active substance prepared by the preparation method described in any one of claims 2-5.

7. The negative electrode electrolyte according to claim 6, wherein The negative electrode electrolyte further includes an alkali solution and a composite additive.

8. The negative electrode electrolyte according to claim 6 or 7, characterized in that The concentration of the organic active substance in the negative electrode electrolyte is 0.1~1 mol / L.

9. The negative electrode electrolyte according to claim 7, characterized in that The alkali solution is one of a potassium hydroxide solution and a sodium hydroxide solution, and the concentration of the alkali solution in the negative electrode electrolyte is 0.5~3 mol / L.

10. The negative electrode electrolyte according to claim 7, characterized in that The composite additive is composed of an inorganic additive and an organic additive according to a mass ratio of 1:(0.05~0.5); the inorganic additive is one of sodium sulfite and potassium sulfite; the organic additive is polyvinylpyrrolidone; the content of the composite additive in the negative electrode electrolyte is 1~10 g / L.

Images