Electrolyte for positive electrode and negative electrode of zinc-bromine flow battery and preparation method of electrolyte

Abstract

The invention relates to the technical field of flow batteries, in particular to an electrolyte for a positive electrode and a negative electrode of a zinc-bromine flow battery and a preparation method of the electrolyte, and the electrolyte comprises zinc oxide, hydrobromic acid, a compound raw material, an additive and deionized water, the compound raw material is formed by mixing crown ether and quaternary ammonium salt. According to the invention, a compound raw material prepared by adding crown ether and quaternary ammonium salt and zinc bromide molecules as an object form a complex through hydrogen bonds, volatilization and self-discharge phenomena of bromine in the electrolyte are weakened after combination, and the charge-discharge characteristics of the battery are optimized; by adding the additive, the additive can cover hydrogen evolution active sites on the zinc surface in the use process of the battery, inhibit the hydrogen evolution reaction in the zinc deposition process and promote the desolvation process of hydrated zinc ions, so that the effects of grain refinement and dendritic crystal inhibition are achieved, and the performance and safety of the battery are guaranteed; the cycle life and the stability of the battery are improved.

Description

Technical Field

[0001] The invention relates to the technical field of liquid flow batteries, and in particular to an electrolyte for positive and negative electrodes of a zinc-bromine liquid flow battery and a preparation method thereof. Background Art

[0002] Liquid flow batteries are also called redox flow batteries or red flow batteries. They are mainly composed of a battery stack unit, an electrolyte, an electrolyte storage and supply unit, and a management and control unit. The working principle of a liquid flow battery is based on the reversible redox reaction of active substances in the positive and negative electrolytes. During the charging process, the valence of the active substances in the positive electrolyte increases, while the valence of the active substances in the negative electrolyte decreases. The discharge process is the opposite. Inside the battery stack, the positive and negative electrolytes are separated by an ion exchange membrane, which allows ions to pass through while preventing the two electrolytes from mixing. Liquid flow batteries convert chemical energy stored in the electrolyte into electrical energy, or convert electrical energy into chemical energy and store it, through an external load and power supply. In liquid flow batteries, the electrolyte plays a role in energy conversion, maintaining battery stability, and preventing battery plate corrosion. As well as heat dissipation, it is an important component of the battery. The positive and negative electrolytes of the existing zinc-bromine flow batteries both use zinc bromide solution, which can basically meet the daily use needs. However, due to the limitations of the raw materials themselves, the bromine in the electrolyte will volatilize and self-discharge during the battery charging and discharging process, affecting the battery charging and discharging characteristics; at the same time, during the oxidation reaction, zinc ions move from the electrolyte solution to the anode and enter the electrolyte solution, and are reduced to Zn metal at the anode. In the process of forming metal, zinc dendrites are easily formed on the electrode surface, and the growth of zinc dendrites will affect the performance and safety of the battery; and in the preparation process, there is a lack of treatment process for the zinc bromide raw materials, and the purity of the raw materials will affect the battery quality of the prepared battery; therefore, it is necessary to design a positive and negative electrolyte for zinc-bromine flow batteries and a preparation method thereof. Summary of the invention

[0003] One of the purposes of the present invention is to provide an electrolyte for positive and negative electrodes of a zinc-bromine flow battery, which has high purity and improves the battery quality of the prepared battery.

[0004] The second object of the present invention is to provide a method for preparing the electrolyte for the positive and negative electrodes of zinc-bromine liquid flow batteries, which has a simple process and is easy to adjust.

[0005] To achieve one of the above purposes, the present invention provides the following technical solution: an electrolyte for positive and negative electrodes of a zinc-bromine liquid flow battery, the formula of which includes: zinc oxide, hydrobromic acid, chemical raw materials, additives and deionized water; the weight proportions of each component are: 50-60 parts of zinc oxide, 47-53 parts of hydrobromic acid, 6-8 parts of chemical raw materials, 5-8 parts of additives and 200-260 parts of deionized water.

[0006] Preferably, the chemical raw material is a mixture of crown ether and quaternary ammonium salt.

[0007] Preferably, the mixing ratio of the crown ether and the quaternary ammonium salt is 1:0.6-1.5, and the crown ether is 18-crown-6.

[0008] Preferably, the additive is prepared by mixing tetrasodium ethylenediaminetetraacetate and tartaric acid in a weight ratio of 5-10:1.

[0009] By adding an additive consisting of tetrasodium ethylenediaminetetraacetic acid and tartaric acid and mixing them in the electrolyte, the additive will cover the hydrogen evolution active sites on the zinc surface during battery use, inhibit the hydrogen evolution reaction during zinc deposition, and promote the desolvation process of hydrated zinc ions, thereby playing a role in grain refinement and dendrite inhibition, ensuring the performance and safety of the battery and improving the cycle life and stability of the battery.

[0010] To achieve the second of the above objectives, the present invention provides the following technical solution: a method for preparing an electrolyte for positive and negative electrodes of a zinc-bromine flow battery,

[0011] The method comprises the following steps: step 1, preparing materials; step 2, mixing and filtering; step 3, preparing zinc bromide; step 4, preparing a primary electrolyte; step 5, preparing an electrolyte;

[0012] In the step 1, weigh each raw material by weight and set aside;

[0013] In the step 2, zinc oxide is slowly added to hydrobromic acid under stirring, and the mixture is filtered after continuous stirring to obtain a preliminary filtrate;

[0014] In the step 3, the preliminary filtrate obtained in the step 2 is heated and concentrated, cooled and crystallized after concentration, and centrifuged to obtain the zinc bromide raw material;

[0015] In the step 4, deionized water, the chemical raw material, and the zinc bromide prepared in the step 3 are mixed and stirred at a constant temperature to obtain a primary electrolyte;

[0016] Step 5: Mix the additive with the primary electrolyte and stir it to obtain the electrolyte for the positive and negative electrodes of the zinc-bromine flow battery.

[0017] Preferably, in step 2, the temperature during continuous stirring is 78-80° C., the stirring speed during continuous stirring is 30-60 r / min, and the continuous stirring time is 18-25 min.

[0018] Preferably, in step three, the temperature for heating and concentrating is 230-250° C.; the speed of centrifugation is 250-300 r / min; and the time of centrifugation is 5-7 min.

[0019] Preferably, in step 4, the temperature of the constant temperature stirring process is 18-25° C., the stirring speed during the constant temperature stirring is 25-36 r / min, and the constant temperature stirring time is 40-50 min.

[0020] Preferably, in step 5, the temperature in the stirrer during the stirring process is 18-25° C., the stirring speed during the stirring process is 36-42 r / min, and the stirring time is 30-40 min.

[0021] Preferably, the prepared electrolyte for the positive and negative electrodes of the zinc-bromine flow battery is stored at a temperature of 18-20°C.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The electrolyte for positive and negative electrodes of a zinc-bromine liquid flow battery of the present invention is prepared by adding a chemical raw material prepared by a crown ether and a quaternary ammonium salt during a mixing process, and a complex is formed with a zinc bromide molecule as a guest through hydrogen bonds. After the combination, the volatilization and self-discharge of bromine in the electrolyte are weakened, and the charge and discharge characteristics of the battery are optimized. The additive is mixed in the electrolyte, and during the use of the battery, the additive covers the hydrogen precipitation active sites on the surface of the zinc, inhibits the hydrogen precipitation reaction during the zinc deposition process, and promotes the desolvation process of hydrated zinc ions, thereby playing the role of grain refinement and dendrite inhibition, ensuring the performance and safety of the battery, and improving the cycle life and stability of the battery.

[0024] The preparation method of the present invention has simple preparation process, is easy to adjust and is suitable for industrial production. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] An electrolyte for positive and negative electrodes of a zinc-bromine liquid flow battery comprises: zinc oxide, hydrobromic acid, a compound raw material, an additive and deionized water; the weight proportions of the components are: 50-60 parts of zinc oxide, 47-53 parts of hydrobromic acid, 6-8 parts of a compound raw material, 5-8 parts of an additive and 200-260 parts of deionized water.

[0027] Preferably, the chemical raw material is a mixture of crown ether and quaternary ammonium salt.

[0028] Preferably, the mixing ratio of the crown ether and the quaternary ammonium salt is 1:0.6-1.5, and the crown ether is 18-crown-6.

[0029] Preferably, the additive is prepared by mixing tetrasodium ethylenediaminetetraacetate and tartaric acid in a weight ratio of 5-10:1.

[0030] A method for preparing an electrolyte for positive and negative electrodes of a zinc-bromine flow battery comprises the following steps:

[0031] Step 1, material preparation; Step 2, mixing and filtering; Step 3, zinc bromide preparation; Step 4, pre-treatment; Step 5, mixing treatment; Step 6, post-treatment; Step 7, low temperature storage;

[0032] In the step 1, weigh each raw material by weight and set aside;

[0033] In the step 2, zinc oxide is slowly added to hydrobromic acid under stirring, and the mixture is filtered after continuous stirring to obtain a preliminary filtrate;

[0034] In the step 3, the preliminary filtrate obtained in the step 2 is heated and concentrated, cooled and crystallized after concentration, and centrifuged to obtain the zinc bromide raw material;

[0035] In the step 4, the zinc bromide raw material obtained in the step 3 is put into water for dissolution, sodium carbonate is added after dissolution for continuous stirring, solid precipitate is obtained by filtering after continuous stirring, and then continuous acid washing is performed, and after acid washing, drying is performed to obtain high-purity zinc bromide;

[0036] In the step 5, deionized water, the chemical raw materials, and the high-purity zinc bromide obtained in the step 4 are mixed and stirred at a constant temperature to obtain a primary electrolyte;

[0037] Step 6, mixing the additive with the primary electrolyte and stirring the mixture to obtain the positive and negative electrolytes of the zinc-bromine flow battery;

[0038] Step seven, sealing the positive and negative electrolytes of the zinc-bromine liquid flow battery obtained in step six and storing them at low temperature.

[0039] Preferably, in step 2, the temperature in the reactor during continuous stirring is 78-80° C., the stirring speed during continuous stirring is 30-60 r / min, and the continuous stirring time is 18-25 min.

[0040] Preferably, in step three, the temperature in the concentration tank during the heating concentration process is 230-250° C.; the centrifugal speed during the spin-drying process is 250-300 r / min, and the spin-drying process time is 5-7 min.

[0041] Preferably, in the step 4, when the zinc bromide raw material is dissolved in water, the amount of water used is 280%-400% of the mass fraction of the zinc bromide raw material, the stirring speed during continuous stirring is 30-60r / min, and the continuous stirring time is 18-25min; during the pickling process, dilute hydrochloric acid with a concentration of 5%-8% is used, and the pickling time is 20-30min.

[0042] Preferably, in step 5, the temperature in the stirrer during the constant temperature stirring is 18-25° C., the stirring speed during the constant temperature stirring is 25-36 r / min, and the constant temperature stirring time is 40-50 min.

[0043] Preferably, in step six, the temperature in the stirrer during the stirring process is 18-25° C., the stirring speed during the stirring process is 36-42 r / min, and the stirring time is 30-40 min.

[0044] Preferably, in step seven, the temperature for low-temperature storage in the low-temperature chamber is 18-20°C.

[0045] Embodiment 1:

[0046] An electrolyte for positive and negative electrodes of a zinc-bromine liquid flow battery, the formula of which includes: zinc oxide, hydrobromic acid, a compound raw material, an additive and deionized water; the weight proportions of the components are: 60 parts of zinc oxide, 53 parts of hydrobromic acid, 8 parts of a compound raw material, 8 parts of an additive and 260 parts of deionized water; the compound raw material is a mixture of a crown ether and a quaternary ammonium salt, and the mixing ratio of the crown ether and the quaternary ammonium salt is 1:0.6; the crown ether used is 18-crown-6; the additive is a mixture of tetrasodium ethylenediaminetetraacetic acid and tartaric acid, and the mass ratio of tetrasodium ethylenediaminetetraacetic acid to tartaric acid is 5:1; zinc oxide and hydrobromic acid are used as zinc source and bromine source of the electrolyte respectively; bromine is generated at the positive electrode during charging after preparation, and bromine is converted back into bromide ions during discharging; and the use of hydrobromic acid can adjust the pH value of the prepared liquid flow battery electrolyte to ensure that the battery operates under optimal working conditions.

[0047] A method for preparing an electrolyte for positive and negative electrodes of a zinc-bromine flow battery comprises the following steps: step 1, preparing materials; step 2, mixing and filtering; step 3, preparing zinc bromide; step 4, preparing a primary electrolyte; step 5, preparing an electrolyte; step 6, storing at low temperature;

[0048] In the above step 1, 60 parts of zinc oxide, 53 parts of hydrobromic acid, 8 parts of chemical raw materials, 8 parts of additives and 260 parts of deionized water are weighed according to the weight of each component and set aside;

[0049] In the above step 2, the hydrobromic acid prepared in the above step 1 is placed in a reactor, and then zinc oxide is slowly added to the reactor, and continuous stirring is performed in the reactor during the addition process. After continuous stirring, the solution in the reactor is filtered to obtain a preliminary filtrate for standby use; during the continuous stirring process, the temperature in the reactor is 80° C., the stirring speed during the continuous stirring is 60 r / min, and the continuous stirring time is 25 min;

[0050] In the above step 3, the preliminary filtrate prepared in the above step 2 is placed in a concentration tank for heating and concentration, and then cooled and crystallized. The crystallization temperature during cooling and crystallization is 50°C; then placed in a centrifuge for spin drying, and the zinc bromide raw material is obtained after spin drying, and placed in a low temperature chamber for storage at a temperature of 15°C for standby; the temperature in the concentration tank during the heating and concentration process is 250°C; the centrifugal speed during the spin drying process is 300r / min, and the spin drying time is 7min;

[0051] In the above step 4, the deionized water and the chemical raw materials obtained in the above step 1 are put into a mixer, and then the zinc bromide prepared in step 3 is added, and then the mixture is stirred at a constant temperature in the mixer. After the constant temperature stirring, a primary electrolyte is obtained, and the electrolyte is stored in the mixer for standby use; during the constant temperature stirring process, the temperature in the mixer is 25° C., the stirring speed during the constant temperature stirring is 36 r / min, and the constant temperature stirring time is 50 min;

[0052] In the above step 5, the additive prepared in the above step 1 is put into a blender and mixed with the primary electrolyte, and then stirred in the blender to obtain the positive and negative electrolytes of the zinc-bromine flow battery for standby use; the temperature in the blender during the stirring process is 25° C., the stirring speed during the stirring process is 42 r / min, and the stirring time is 40 min;

[0053] In the above step six, the positive and negative electrolytes of the zinc-bromine liquid flow battery prepared in the above step five are placed in a sealed can, and then stored in a low-temperature chamber for low-temperature storage. The temperature for low-temperature storage in the low-temperature chamber is 20°C.

[0054] Embodiment 2:

[0055] An electrolyte for positive and negative electrodes of a zinc-bromine liquid flow battery, the formula of which includes: zinc oxide, hydrobromic acid, a compound raw material, an additive and deionized water; the weight proportions of the components are: 50 parts of zinc oxide, 47 parts of hydrobromic acid, 6 parts of a compound raw material, 5 parts of an additive and 200 parts of deionized water; the compound raw material is a mixture of a crown ether and a quaternary ammonium salt, and the mixing ratio of the crown ether and the quaternary ammonium salt is 1:1; the crown ether used is 18-crown-6; the additive is a mixture of tetrasodium ethylenediaminetetraacetate and tartaric acid, and the mass ratio of tetrasodium ethylenediaminetetraacetate to tartaric acid is 7:1; zinc oxide and hydrobromic acid are used as zinc source and bromine source of the electrolyte respectively; bromine is generated at the positive electrode during charging after preparation, and bromine is converted back into bromide ions during discharging; and the use of hydrobromic acid can adjust the pH value of the prepared liquid flow battery electrolyte to ensure that the battery operates under optimal working conditions.

[0056] A method for preparing an electrolyte for positive and negative electrodes of a zinc-bromine flow battery comprises the following steps: step 1, preparing materials; step 2, mixing and filtering; step 3, preparing zinc bromide; step 4, preparing a primary electrolyte; step 5, preparing an electrolyte; step 6, storing at low temperature;

[0057] In the above step 1, 50 parts of zinc oxide, 47 parts of hydrobromic acid, 6 parts of chemical raw materials, 5 parts of additives and 200 parts of deionized water are weighed according to the weight of each component and set aside;

[0058] In the above step 2, the hydrobromic acid prepared in the above step 1 is placed in a reactor, and then zinc oxide is slowly added to the reactor, and continuous stirring is performed in the reactor during the addition process. After continuous stirring, the solution in the reactor is filtered to obtain a preliminary filtrate for standby use; the temperature in the reactor during the continuous stirring process is 78° C., the stirring speed during the continuous stirring is 30 r / min, and the continuous stirring time is 18 min;

[0059] In the above step 3, the preliminary filtrate prepared in the above step 2 is placed in a concentration tank for heating and concentration, and then cooled and crystallized. The crystallization temperature during cooling and crystallization is 45°C; then placed in a centrifuge for spin drying. After the spin drying, the zinc bromide raw material is obtained, and placed in a low temperature chamber at a temperature of 15°C for storage for standby; the temperature in the concentration tank during the heating and concentration process is 230°C; the centrifugal speed during the spin drying process is 250r / min, and the spin drying time is 5min;

[0060] In the above step 4, the deionized water and the chemical raw materials obtained in the above step 1 are put into a mixer, and then the zinc bromide prepared in step 3 is added, followed by constant temperature stirring in the mixer, and a primary electrolyte is obtained after constant temperature stirring, and is stored in the mixer for standby use; during the constant temperature stirring process, the temperature in the mixer is 18° C., the stirring speed during the constant temperature stirring is 25 r / min, and the constant temperature stirring time is 40 min;

[0061] In the above step 5, the additive prepared in the above step 1 is put into a blender and mixed with the primary electrolyte, and then stirred in the blender to obtain the positive and negative electrolytes of the zinc-bromine flow battery for standby use; the temperature in the blender during the stirring process is 18° C., the stirring speed during the stirring process is 36 r / min, and the stirring time is 30 min;

[0062] In the above step six, the positive and negative electrolytes of the zinc-bromine liquid flow battery prepared in the above step five are placed in a sealed can, and then stored in a cryogenic chamber for low-temperature storage. The temperature for low-temperature storage in the cryogenic chamber is 18°C.

[0063] Embodiment 3:

[0064] An electrolyte for positive and negative electrodes of a zinc-bromine liquid flow battery comprises: zinc oxide, hydrobromic acid, a compound raw material, an additive and deionized water; the weight proportions of the components are: 60 parts of zinc oxide, 47 parts of hydrobromic acid, 8 parts of a compound raw material, 5 parts of an additive and 260 parts of deionized water; the compound raw material is a mixture of a crown ether and a quaternary ammonium salt, and the mixing ratio of the crown ether and the quaternary ammonium salt is 1:1.5; the crown ether used is 18-crown-6; the additive is a mixture of tetrasodium ethylenediaminetetraacetic acid and tartaric acid, and the mass ratio of tetrasodium ethylenediaminetetraacetic acid to tartaric acid is 10:1; zinc oxide and hydrobromic acid are used as zinc source and bromine source of the electrolyte respectively; bromine is generated at the positive electrode during charging after preparation, and bromine is converted back into bromide ions during discharging; and the use of hydrobromic acid can adjust the pH value of the prepared liquid flow battery electrolyte to ensure that the battery operates under optimal working conditions.

[0065] A method for preparing an electrolyte for positive and negative electrodes of a zinc-bromine flow battery comprises the following steps: step 1, preparing materials; step 2, mixing and filtering; step 3, preparing zinc bromide; step 4, preparing a primary electrolyte; step 5, preparing an electrolyte; step 6, storing at low temperature;

[0066] In the above step 1, 60 parts of zinc oxide, 47 parts of hydrobromic acid, 8 parts of chemical raw materials, 5 parts of additives and 260 parts of deionized water are weighed according to the weight of each component and set aside;

[0067] In the above step 2, the hydrobromic acid prepared in the above step 1 is placed in a reactor, and then zinc oxide is slowly added to the reactor, and continuous stirring is performed in the reactor during the addition process. After continuous stirring, the solution in the reactor is filtered to obtain a preliminary filtrate for standby use; during the continuous stirring process, the temperature in the reactor is 80° C., the stirring speed during the continuous stirring is 30 r / min, and the continuous stirring time is 25 min;

[0068] In the above step 3, the preliminary filtrate prepared in the above step 2 is placed in a concentration tank for heating and concentration, and then cooled and crystallized. The crystallization temperature during cooling and crystallization is 60°C; then placed in a centrifuge for spin drying. After spin drying, the zinc bromide raw material is obtained, and placed in a low temperature chamber at a temperature of 15°C for storage for standby; the temperature in the concentration tank during the heating and concentration process is 230°C; the centrifugal speed during the spin drying process is 300r / min, and the spin drying time is 5min;

[0069] In the above step 4, the deionized water and the chemical raw materials obtained in the above step 1 are put into a mixer, and then the zinc bromide prepared in step 3 is added, and then the mixture is stirred at a constant temperature in the mixer. After the constant temperature stirring, a primary electrolyte is obtained, and the electrolyte is stored in the mixer for standby use; during the constant temperature stirring process, the temperature in the mixer is 18° C., the stirring speed during the constant temperature stirring is 36 r / min, and the constant temperature stirring time is 40 min;

[0070] In the above step 5, the additive prepared in the above step 1 is put into a blender and mixed with the primary electrolyte, and then stirred in the blender to obtain the positive and negative electrolytes of the zinc-bromine flow battery for standby use; the temperature in the blender during the stirring process is 25° C., the stirring speed during the stirring process is 36 r / min, and the stirring time is 40 min;

[0071] In the above step six, the positive and negative electrolytes of the zinc-bromine liquid flow battery prepared in the above step five are placed in a sealed can, and then stored in a cryogenic chamber for low-temperature storage. The temperature for low-temperature storage in the cryogenic chamber is 18°C.

[0072] The positive and negative electrolytes of the zinc-bromine flow battery obtained in the above example were tested for performance, and compared with the E05-E-black-oxygen battery electrolyte. The results are shown in the following table:

[0073] Doping rate Conductivity (mS / cm) Example 1 1.04％ 456 Example 2 0.98％ 487 Example 3 1.03％ 465 E05-E-black-oxygen battery electrolyte 3.35％ 285

[0074] Based on the above, the advantages of the present invention are that, in the present invention, a compound raw material prepared by adding a crown ether and a quaternary ammonium salt during a mixing process is formed with a zinc bromide molecule as a guest through hydrogen bonds, and after the combination, the volatilization and self-discharge of bromine in the electrolyte are weakened, and the charge and discharge characteristics of the battery are optimized; and an additive composed of tetrasodium ethylenediaminetetraacetic acid and tartaric acid is added and mixed in the electrolyte, and during the use of the battery, the additive will cover the hydrogen precipitation active site on the zinc surface, inhibit the hydrogen precipitation reaction in the zinc deposition process, and promote the desolvation process of hydrated zinc ions, thereby playing a role in grain refinement and dendrite inhibition, ensuring the performance and safety of the battery, and improving the cycle life and stability of the battery.

[0075] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. An electrolyte for positive and negative electrodes of a zinc-bromine flow battery, characterized in that: The composition comprises, by weight: 50-60 parts of zinc oxide, 47-53 parts of hydrobromic acid, 6-8 parts of compound raw materials, 5-8 parts of additives and 200-260 parts of deionized water; The compound raw material is prepared by mixing crown ether and quaternary ammonium salt.

2. The electrolyte for positive and negative electrodes of zinc-bromine flow battery according to claim 1, characterized in that: The mixing weight ratio of the crown ether and the quaternary ammonium salt is 1:0.6-1.

5.

3. The electrolyte for positive and negative electrodes of zinc-bromine flow battery according to claim 1, characterized in that: The crown ether is 18-crown-6.

4. The electrolyte for positive and negative electrodes of zinc-bromine flow battery according to claim 1, characterized in that: The additive is prepared by mixing tetrasodium ethylenediaminetetraacetate and tartaric acid in a weight ratio of 5-10:

1.

5. A method for preparing an electrolyte for positive and negative electrodes of a zinc-bromine flow battery as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1, preparing materials; Step 2, mixing and filtering; Step 3, preparing zinc bromide; Step 4, preparing a primary electrolyte; Step 5, preparing an electrolyte; In the step 1, weigh each raw material by weight and set aside; In the step 2, zinc oxide is slowly added to hydrobromic acid under stirring, and the mixture is filtered after continuous stirring to obtain a preliminary filtrate; In the step 3, the preliminary filtrate obtained in the step 2 is heated and concentrated, cooled and crystallized after concentration, and centrifuged to obtain the zinc bromide raw material; In the step 4, deionized water, the chemical raw material, and the zinc bromide prepared in the step 3 are mixed and stirred at a constant temperature to obtain a primary electrolyte; Step 5: Mix the additive with the primary electrolyte and stir it to obtain the electrolyte for the positive and negative electrodes of the zinc-bromine flow battery.

6. The method for preparing the electrolyte for the positive and negative electrodes of zinc-bromine flow battery according to claim 5, characterized in that: In the step 2, the temperature during continuous stirring is 78-80° C., the stirring speed during continuous stirring is 30-60 r / min, and the continuous stirring time is 18-25 min.

7. The method for preparing the electrolyte for the positive and negative electrodes of zinc-bromine flow battery according to claim 5, characterized in that: In the step 3, the temperature of heating and concentrating is 230-250° C.; the speed of centrifugation is 250-300 r / min, and the time of centrifugation is 5-7 min.

8. The method for preparing the electrolyte for the positive and negative electrodes of zinc-bromine flow battery according to claim 5, characterized in that: In the step 4, the temperature of the constant temperature stirring process is 18-25° C., the stirring speed during the constant temperature stirring is 25-36 r / min, and the constant temperature stirring time is 40-50 min.

9. The method for preparing the electrolyte for the positive and negative electrodes of zinc-bromine flow battery according to claim 5, characterized in that: In the step 5, the temperature in the stirrer during the stirring process is 18-25° C., the stirring speed during the stirring process is 36-42 r / min, and the stirring time is 30-40 min.

10. The method for preparing the electrolyte for the positive and negative electrodes of zinc-bromine flow battery according to claim 5, characterized in that: The prepared electrolyte for the positive and negative electrodes of the zinc-bromine flow battery is stored at a temperature of 18-20°C.