Negative electrode electrolyte, preparation method thereof and total iron flow battery

Abstract

The invention belongs to the field of batteries, and particularly relates to a negative electrode electrolyte, a preparation method thereof and an all-iron flow battery. The negative electrode electrolyte comprises iron ions, ferrous ions, a first ligand, a supporting electrolyte and water; the first ligand is ethylene triamine penta (methylene phosphonic acid) X sodium salt-DTPMPNAX (diethylenetriamine penta (methylene phosphonic acid)). According to the technical scheme, hydrolysis of iron ions is weakened through the first ligand, generation of precipitates in the electrolyte preparing and testing process is improved, the first ligand can be dissolved in water under the condition of the high pH value, and it is ensured that the pH value of the positive electrode electrolyte and the pH value of the negative electrode electrolyte are matched. Particularly, the preferable diethylene triamine pentamethylene phosphonic acid X sodium salt-DTPMPNAX is provided, so that the cost is relatively low, the material price is low, high-price equipment is not required to be used, and the cycle life of the total-iron flow battery is prolonged at relatively low cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of batteries, and particularly relates to a negative electrolyte, a preparation method thereof and a full-iron flow battery. BACKGROUND

[0002] China has a vast territory and rich wind and solar energy resources. However, the supply of these natural resources has the characteristics of discontinuity and instability, and direct access to the power grid will cause many challenges, so it is necessary to carry out stability treatment first. In addition, the supply and demand of electricity often do not match in time and space, showing peaks and troughs of demand, as well as imbalances in supply and demand in different regions. The key strategy to cope with these challenges is to develop energy storage technology, especially electrochemical energy storage technology, which has the advantages of high efficiency, fast response and small geographical limitation, and is suitable for both stability adjustment of wind and solar power generation and management of the demand side of electricity. Among many electrochemical energy storage technologies, flow batteries, as an innovative electrochemical energy storage technology, store energy in liquid electrolytes and convert chemical energy into electrical energy through electrochemical reactions. It has many advantages, including flexible system design, deep charge and discharge, high energy conversion efficiency, and safety and environmental protection. These characteristics make flow batteries show great potential in applications such as grid integration and peak regulation of new energy power generation.

[0003] As the most mature flow battery technology, the all-vanadium redox flow battery has good commercial prospects due to its good stability, fast response speed, high efficiency and long cycle life. However, affected by the price fluctuations of vanadium ore, the cost of electrolyte continues to be high, accounting for more than 40% of the total energy storage cost, which not only raises the overall cost of the system, but also limits its large-scale commercial application in the energy storage field. Therefore, in order to break this bottleneck, it is particularly urgent and necessary to develop a new type of low-cost aqueous flow battery system.

[0004] The full-iron flow battery uses iron ions as the active material of the positive and negative electrodes, and uses inexpensive iron as the raw material, which greatly reduces the cost of the electrolyte and the overall system, showing high cost-effectiveness. The open-circuit voltage of this battery is 1.21V, similar to that of the all-vanadium flow battery, and can avoid cross contamination. The active material is widely available and low in price. However, the full-iron flow battery faces some technical challenges, including low solubility of active materials in electrolyte, high degree of side reactions, and ion transmembrane migration problems, which limit the energy efficiency and cycle life of the battery. In particular, the poor reversibility of the hydrolysis and deposition / dissolution reactions of ferrous ions in the negative electrolyte, as well as the severity of the hydrogen evolution reaction, further lead to low energy efficiency and capacity decay problems, affecting its cycle stability and widespread application in energy storage technology. SUMMARY

[0005] The application aims at overcoming the defects in the prior art, and provides a negative electrolyte, a preparation method thereof and a full-iron flow battery.

[0006] To achieve the above-mentioned purpose, the application adopts the technical scheme of:

[0007] The negative electrolyte comprises iron ions, ferrous ions, a first ligand, a supporting electrolyte and water; the first ligand is one or a combination of bis(2-hydroxyethyl)amino(trishydroxymethyl)methane, triethanolamine, 3-bis(2-hydroxyethyl)amino-2-hydroxypropanesulfonic acid and diethylenetriamine pentamethylene phosphonic acid X sodium salt (DTPMPNAX); preferably, the first ligand is diethylenetriamine pentamethylene phosphonic acid X sodium salt (DTPMPNAX).

[0008] The concentration of the first ligand is 0.1-3.0 mol / L; preferably, the molar ratio of the first ligand to the iron ions is (1.5-2):1; preferably, the concentration of the first ligand is 0.15-0.9 mol / L, and more preferably, the concentration of the first ligand is 0.9 mol / L.

[0009] The second ligand is one or a combination of L-tartaric acid, D-tartaric acid, MESO-tartaric acid, DL-tartaric acid, L-malic acid, D-malic acid, DL-malic acid and gallic acid.

[0010] The concentration of the second ligand is 0.1-3.0 mol / L; preferably, the molar ratio of the second ligand to the iron ions is 1:1; preferably, the concentration of the second ligand is 0.6 mol / L.

[0011] The iron ions are derived from one or more of ferric chloride, ferric sulfate and ferric nitrate, and the concentration of the iron ions is 0.1-2.0 mol / L; preferably, the concentration of the iron ions is 0.1-0.6 mol / L; more preferably, the concentration of the iron ions is 0.6 mol / L.

[0012] The ferrous ions are derived from one or more of ferrous chloride, ferrous sulfate and ferrous nitrate, and the concentration of the ferrous ions is 0-2 mol / L.

[0013] The supporting electrolyte is one or more of sodium hydroxide, potassium hydroxide and lithium hydroxide, and the concentration of the supporting electrolyte is 3.5-8 mol / L; preferably, the concentration of the supporting electrolyte is 4 mol / L.

[0014] The application further comprises a preparation method of the negative electrolyte, which comprises the following steps: 1) respectively adding iron ions, optionally containing ferrous ions, a first ligand, optionally containing a second ligand and a supporting electrolyte into deionized water to form solutions; and 2) adding the supporting electrolyte solution into the first ligand solution, and optionally adding the second ligand solution into the mixture of the iron ions and the optional ferrous ions.

[0015] The application also includes a full-iron flow battery, comprising a positive electrode, a negative electrode, a positive electrolyte, the negative electrolyte of any one of claims 1-7, a separator and a battery housing, wherein the positive electrode, the negative electrode and the separator are accommodated in the battery housing.

[0016] The positive electrolyte comprises ferricyanide and a positive electrolyte; the ferricyanide comprises one or a mixture of ferricyanide or ferrocyanide; preferably, the molar concentration of ferricyanide is 0.1-2.0 mol / L; preferably, 0.6 mol / L;

[0017] The ferricyanide is one or a mixture of sodium ferricyanide, potassium ferricyanide, lithium ferricyanide; the ferrocyanide is one or a mixture of sodium ferrocyanide, potassium ferrocyanide, lithium ferrocyanide;

[0018] Preferably, the positive electrolyte comprises a positive supporting electrolyte and a positive auxiliary electrolyte;

[0019] Preferably, the positive supporting electrolyte is an alkaline substance, preferably, the positive supporting electrolyte is one or a mixture of sodium hydroxide, potassium hydroxide, lithium hydroxide;

[0020] Preferably, the molar concentration of the positive supporting electrolyte is 0.1-4.0 mol / L; preferably, 3 mol / L;

[0021] Preferably, the positive auxiliary electrolyte is one or a mixture of potassium chloride, potassium nitrate, sodium nitrate, sodium chloride, ammonium chloride, potassium sulfate, sodium sulfate, ammonium sulfate;

[0022] Preferably, the molar concentration of the positive auxiliary electrolyte is 0-1.0 mol / L.

[0023] Compared with the prior art, the application has the following beneficial effects:

[0024] In the technical solution of the application, the first ligand reduces the hydrolysis of iron ions, improves the generation of precipitates in the preparation and testing process of the electrolyte, can be dissolved in water under high pH conditions, and ensures that the pH of the positive and negative electrolytes matches. Especially the proposal of diethylenetriamine pentamethylene phosphonic acid X sodium salt-DTPMPNAX as a preferred one, the cost is low, and the material price is cheap, without the need to use high-priced equipment, to improve the cycle life of the full-iron flow battery at a lower cost.

[0025] The addition of the second ligand can effectively avoid the generation of precipitates in the preparation of the alkaline full-iron flow battery negative electrolyte, while improving the stability of ferrous ions, greatly enhancing the solubility of complex iron, improving the total iron concentration, and effectively improving the energy efficiency and cycle life of the alkaline full-iron flow battery.

[0026] In summary, the alkaline all-iron liquid flow battery provided by the present invention has the characteristics of low cost, environmental protection, flame retardancy, and high safety, while providing long-term stable circulation for the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the structural diagram of diethylenetriaminepentamethylenephosphonic acid X sodium salt - DTPMPNAX;

[0028] Figure 2 This is a performance diagram of different charge and discharge rates of the flow battery assembled in Example 1 of the present invention;

[0029] Figure 3 This is a performance diagram of different charge and discharge rates of the flow battery assembled in Example 3 of the present invention; DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and the best embodiments.

[0031] Example 1

[0032] Example 1: Anode electrolyte and all-iron flow battery based on diethylenetriaminepentamethylenephosphonic acid X sodium salt-DTPMPNAX-iron ion.

[0033] 1. Preparation method of negative electrode electrolyte based on diethylenetriamine penta methylenephosphonic acid X sodium salt - DTPMPNAX - iron ion:

[0034] 1) First, add 0.03 mol Fe2(SO4)3 to 30 ml of deionized water and stir continuously until the solid is completely dissolved (about 20 minutes) to form solution 1.

[0035] 2) Weigh 0.09 mol of diethylenetriaminepentamethylenephosphonic acid X sodium salt (DTPMPNAX) and add it to 10 ml of deionized water. Stir continuously (about 10 minutes) to form Solution 2.

[0036] 3) Weigh 0.4 mol NaOH and add it to 20 ml deionized water. Stir continuously until the solid is completely dissolved (about 10 minutes) to form solution 3

[0037] 4) Slowly add Solution 3 to Solution 2, stirring continuously during the addition. After complete addition, stir at 600 rpm for 30 minutes to form Solution 4.

[0038] 5) Slowly add solution 1 to solution 4, continuously stirring during the addition. After complete addition, stir at 800 rpm for 6 h to obtain solution 6. Dilute to 100 ml in a volumetric flask to obtain 100 ml of diethylene triamine pentamethylene phosphonic acid X sodium salt-DTPMPNAX (0.9 mol / L)-iron ion (0.6 mol / L) complex solution ready for use.

[0039] 2. Positive electrolyte preparation:

[0040] 1) First, weigh 0.06 mol K4[Fe(CN)6] and add to 60 ml of deionized water, continuously stirring until the solid is completely dissolved (about 20 min) to obtain solution 1.

[0041] 2) Weigh 0.3 mol NaOH and add to 20 ml of deionized water, continuously stirring until the solid is completely dissolved (about 10 min) to form solution 2.

[0042] 3) Slowly add solution 2 to solution 1, after complete addition, stir at 600 rpm to obtain solution 3. Place solution 3 in a 100 ml volumetric flask and dilute to volume with deionized water to obtain 100 ml of 0.6 mol / L K4[Fe(CN)6] solution ready for use.

[0043] 3. Full iron redox flow battery assembly:

[0044] The single cell is assembled in the following order: positive electrode (positive electrode end plate, insulating pad, copper plate, graphite current collector, sealing pad, positive electrode 5 mm x 5 cm x 5 cm carbon felt), ion exchange membrane Nafion 115, negative electrode (negative electrode 5 mm x 5 cm x 5 cm carbon felt, sealing pad, graphite current collector, copper plate, insulating pad, negative electrode end plate).

[0045] 4. Full iron redox flow battery test conditions:

[0046] The flow rate of the positive and negative electrolyte during the operation of the battery is 100 mL / min, and the charge and discharge test is carried out at different current densities, with the charge and discharge cut-off voltage set at 1.6 V and 0.5 V, respectively.

[0047] Examples 2-4 differ from Example 1 only in the negative electrolyte, and the positive electrolyte as well as the assembly and test conditions of the full iron redox flow battery are the same.

[0048] Example 2

[0049] Negative electrolyte based on diethylene triamine pentamethylene phosphonic acid X sodium salt-DTPMPNAX-iron ion-tartaric acid and full iron redox flow battery.

[0050] 1. A method for preparing a negative electrolyte based on diethylenetriamine pentamethylene phosphonic acid X sodium salt - DTPMPNAX - iron ions - tartaric acid:

[0051] 1) First, 0.03 mol Fe2(S04)3 was added to 30 ml of deionized water, and stirred constantly until the solid was completely dissolved (about 20 min), forming solution 1.

[0052] 2) 0.09 mol diethylenetriamine pentamethylene phosphonic acid X sodium salt - DTPMPNAX was weighed and added to 10 ml of deionized water, and stirred constantly (about 10 min), forming solution 2.

[0053] 3) 0.4 mol NaOH was weighed and added to 20 ml of deionized water, and stirred constantly until the solid was completely dissolved (about 10 min), forming solution 3;

[0054] 4) Solution 3 was slowly added to solution 2, and stirred constantly during the addition. After complete addition, it was stirred at 600 rpm for 30 min, forming solution 4.

[0055] 4) 0.06 mol L tartaric acid was slowly added to solution 1, and stirred at 600 rpm for 30 min, obtaining solution 5.

[0056] 6) Solution 5 was slowly added to solution 4, and stirred constantly during the addition. After complete addition, it was stirred at 800 rpm for 6 h, obtaining solution 6, which was made up to 100 ml in a volumetric flask, obtaining 100 ml of a diethylenetriamine pentamethylene phosphonic acid X sodium salt - DTPMPNAX (0.9 mol / L) - iron ions (0.6 mol / L) - L tartaric acid (0.6 mol / L) complex solution, which was ready for use.

[0057] Example 3

[0058] Negative electrolyte based on bis(2-hydroxyethyl)amino(trishydroxymethyl)methane - iron ions - tartaric acid and all-iron flow battery.

[0059] 1. A method for preparing a negative electrolyte based on bis(2-hydroxyethyl)amino(trishydroxymethyl)methane - iron ions - tartaric acid:

[0060] 1) First, 0.03 mol Fe2(S04)3 was added to 30 ml of deionized water, and stirred constantly until the solid was completely dissolved (about 20 min), forming solution 1.

[0061] 2) 0.12 mol bis(2-hydroxyethyl)amino(trishydroxymethyl)methane was weighed and added to 40 ml of deionized water, and stirred constantly until the solid was completely dissolved (about 10 min), forming solution 2.

[0062] 3) Slowly add solution 2 to solution 1, stirring constantly during the addition. After complete addition, stir at 600 rpm for 30 min to form solution 3.

[0063] 4) Slowly add 0.06 mol L-tartaric acid to solution 3, stirring at 600 rpm for 30 min to obtain solution 4.

[0064] 5) Weigh 0.4 mol NaOH into 20 ml of deionized water, stirring constantly until the solid is completely dissolved (about 10 min) to form solution 5.

[0065] 6) Slowly add solution 5 to solution 4, stirring constantly during the addition. After complete addition, stir at 800 rpm for 6 h to obtain solution 6, which is diluted to 100 ml in a volumetric flask to obtain 100 ml of a bis(2-hydroxyethyl)amino(trishydroxymethyl)methane (1.2 mol / L)-iron ion (0.6 mol / L)-L-tartaric acid (0.6 mol / L) complex solution for use.

[0066] Example 4

[0067] Triethanolamine-iron ion-tartaric acid-based negative electrolyte and full iron flow battery.

[0068] 1. Preparation method of triethanolamine-iron ion-tartaric acid-based negative electrolyte:

[0069] 1) First, add 0.03 mol Fe2(S04)3 to 30 ml of deionized water, stirring constantly until the solid is completely dissolved (about 20 min) to form solution 1.

[0070] 2) Weigh 0.12 mol of triethanolamine into 40 ml of deionized water, stirring constantly (about 10 min) to form solution 2.

[0071] 3) Slowly add solution 2 to solution 1, stirring constantly during the addition. After complete addition, stir at 600 rpm for 30 min to form solution 3.

[0072] 4) Slowly add 0.06 mol L-tartaric acid to solution 3, stirring at 600 rpm for 30 min to obtain solution 4.

[0073] 5) Weigh 0.4 mol NaOH into 20 ml of deionized water, stirring constantly until the solid is completely dissolved (about 10 min) to form solution 5.

[0074] 6) Slowly add solution 5 to solution 4, continuously stirring during the addition. After complete addition, stir at 800 rpm for 6 h to obtain solution 6. Dilute to 100 ml in a volumetric flask to obtain 100 ml of triethanolamine (1.2 mol / L)-iron ion (0.6 mol / L)-L-tartaric acid (0.6 mol / L) complex solution for use.

[0075] Example 5

[0076] 3-bis(2-hydroxyethyl)amino-2-hydroxypropane sulfonic acid-iron ion-tartaric acid based negative electrolyte and all-iron flow battery.

[0077] 1. A method for preparing a 3-bis(2-hydroxyethyl)amino-2-hydroxypropane sulfonic acid-iron ion-tartaric acid based negative electrolyte:

[0078] 1) First, add 0.03 mol Fe2(S04)3 to 30 ml of deionized water, continuously stirring until the solid is completely dissolved (about 20 min) to form solution 1.

[0079] 2) Weigh 0.12 mol of 3-bis(2-hydroxyethyl)amino-2-hydroxypropane sulfonic acid into 40 ml of deionized water, continuously stirring until the solid is completely dissolved (about 10 min) to form solution 2.

[0080] 3) Slowly add solution 2 to solution 1, continuously stirring during the addition. After complete addition, stir at 600 rpm for 30 min to form solution 3.

[0081] 4) Slowly add 0.06 mol of L-tartaric acid to solution 3, and stir at 600 rpm for 30 min to obtain solution 4.

[0082] 5) Weigh 0.4 mol of NaOH into 20 ml of deionized water, continuously stirring until the solid is completely dissolved (about 10 min) to form solution 5.

[0083] 6) Slowly add solution 5 to solution 4, continuously stirring during the addition. After complete addition, stir at 800 rpm for 6 h to obtain solution 6. Dilute to 100 ml in a volumetric flask to obtain 100 ml of triethanolamine (1.2 mol / L)-iron ion (0.6 mol / L)-L-tartaric acid (0.6 mol / L) complex solution for use.

[0084] It should be noted that the naming of the comparative examples is for the purpose of comparison, and they are also part of the examples.

[0085] Comparative Examples 1-3

[0086] To simplify the description, enhance the contrast effect, the diethylene triamine pentamethylene phosphonic acid X sodium salt-DTPMPNAX in example 1 is replaced by the same concentration of triethanolamine, bis(2-hydroxyethyl) amino (trihydroxymethyl) methane, 3-bis(2-hydroxyethyl) amino-2-hydroxypropane sulfonic acid, and the rest of the conditions are exactly the same as example 1.

[0087] Comparative examples 4-6

[0088] To simplify the description, enhance the contrast effect, comparative examples 4-6 are respectively based on examples 3-5 without tartaric acid component, and the rest of the conditions are the same. The performance of the alkaline all-iron flow battery is shown in Table 1.

[0089] Table 1

[0090]

[0091] Comparative examples 7-9

[0092] Different concentrations of diethylene triamine pentamethylene phosphonic acid X sodium salt-DTPMPNAX-iron ion negative electrolyte and all-iron flow battery.

[0093] To simplify the description, enhance the contrast effect, comparative examples 7-9: respectively, the electrolyte formula prepared under different concentrations and its performance in the all-iron flow battery. The only change is the content of diethylene triamine pentamethylene phosphonic acid X sodium salt-DTPMPNAX, and the rest of the steps are exactly the same as example 1. The specific parameters are shown in Table 2.

[0094] Table 2

[0095]

[0096] From the parameters in Tables 1-2, it can be seen that the first ligand in the technical solution of the application weakens the hydrolysis of iron ions, improves the generation of precipitates during electrolyte preparation and testing, and can be dissolved in water under high pH conditions, ensuring that the pH of the positive and negative electrolytes matches. Especially the proposal of diethylene triamine pentamethylene phosphonic acid X sodium salt-DTPMPNAX as a preferred one, the cost is low, and the material price is cheap, without the need to use high-priced equipment, to improve the cycle life of the all-iron flow battery at a lower cost.

[0097] The addition of the second ligand can effectively avoid the generation of precipitates during the preparation of the negative electrolyte of the alkaline all-iron flow battery, while improving the stability of ferrous ions, greatly enhancing the solubility of complex iron, increasing the total iron concentration, and effectively improving the energy efficiency and cycle life of the alkaline all-iron flow battery.

[0098] In summary, the alkaline all-iron flow battery provided by the application has the characteristics of low cost, environmental protection, flame retardation, and high safety, while providing long-term stable cycle for the battery.

[0099] The above merely describes the preferred embodiments of the present application, and it should be pointed out that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A negative electrode electrolyte, characterized in that The invention comprises ferric ions, ferrous ions, a first ligand, a supporting electrolyte and water; the first ligand is one or a combination of bis(2-hydroxyethyl)amino(trihydroxymethyl)methane, triethanolamine, 3-bis(2-hydroxyethyl)amino-2-hydroxypropanesulfonic acid, and diethylenetriaminepentamethylenephosphonic acid X sodium salt -DTPMPNAX; preferably diethylenetriaminepentamethylenephosphonic acid X sodium salt -DTPMPNAX.

2. The negative electrode electrolyte according to claim 1, characterized in that The concentration of the first ligand is 0.1-3.0 mol / L; preferably, the molar ratio of the first ligand to the iron ion is (1.5-2):1; preferably 0.15-0.9 mol / L, more preferably 0.9 mol / L.

3. The negative electrode electrolyte according to claim 1, characterized in that It also includes a second ligand; the second ligand is one or a combination of L-tartaric acid, D-tartaric acid, MESO-tartaric acid, DL-tartaric acid, L-malic acid, D-malic acid, DL-malic acid, and gallic acid.

4. The negative electrode electrolyte according to claim 3, characterized in that The concentration of the second ligand is 0.1-3.0 mol / L; preferably, the molar ratio of the second ligand to the iron ion is 1:1; preferably 0.6 mol / L.

5. The negative electrode electrolyte according to claim 1, characterized in that The iron ions are derived from one or more of ferric chloride, ferric sulfate, and ferric nitrate, and the concentration of the iron ions is 0.1-2.0 mol / L, preferably 0.1-0.6 mol / L, and more preferably 0.6 mol / L.

6. The negative electrode electrolyte according to claim 1, characterized in that The ferrous ions are derived from one or more of ferrous chloride, ferrous sulfate, and ferrous nitrate, and the concentration of the ferrous ions is 0-2 mol / L.

7. The negative electrode electrolyte according to claim 1, characterized in that The supporting electrolyte is one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide, and the concentration of the supporting electrolyte is 3.5-8 mol / L, preferably 4 mol / L.

8. A method for preparing the negative electrode electrolyte according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: 1) adding ferric ions, optionally ferrous ions, a first ligand, optionally a second ligand and a supporting electrolyte into deionized water to form solutions respectively; 2) adding the supporting electrolyte solution into the first ligand solution, optionally into the mixed solution of the second ligand solution and the ferric ions, optionally ferrous ions.

9. An all-iron liquid flow battery, characterized in that: The battery comprises a positive electrode, a negative electrode, a positive electrode electrolyte, the negative electrode electrolyte according to any one of claims 1 to 7, a separator and a battery shell, wherein the positive electrode, the negative electrode and the separator are accommodated in the battery shell.

10. The all-iron liquid flow battery according to claim 9, characterized in that: The positive electrode electrolyte includes ferricyanide and a positive electrode electrolyte; the ferricyanide includes one or a mixture of ferrocyanide and ferrocyanide; preferably, the molar concentration of the ferricyanide is 0.1-2.0 mol / L, preferably 0.6 mol / L; The ferrocyanide is a mixture of one or more of sodium ferrocyanide, potassium ferrocyanide, and lithium ferrocyanide; the ferrocyanide is a mixture of one or more of sodium ferrocyanide, potassium ferrocyanide, and lithium ferrocyanide; Preferably, the positive electrode electrolyte includes a positive electrode supporting electrolyte and a positive electrode auxiliary electrolyte; Preferably, the positive electrode supporting electrolyte is an alkaline substance, preferably, the positive electrode supporting electrolyte is a mixture of one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide; Preferably, the molar concentration of the positive electrode supporting electrolyte is in the range of 0.1-4.0 mol / L; preferably 3 mol / L; Preferably, the positive electrode auxiliary electrolyte is a mixture of one or more of potassium chloride, potassium nitrate, sodium nitrate, sodium chloride, ammonium chloride, potassium sulfate, sodium sulfate, and ammonium sulfate; Preferably, the molar concentration of the positive electrode auxiliary electrolyte is 0-1.0 mol / L.

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