Repair method of unbalanced battery electrolyte

Abstract

The present invention relates to electrolyte repair and discloses a method for repairing an unbalanced battery electrolyte. The method comprises: mixing the anolyte and catholyte of an unbalanced battery to obtain a mixed electrolyte I; preparing a pentavalent ion electrolyte of metal cations in the mixed electrolyte I; mixing the pentavalent ion electrolyte with the mixed electrolyte I to obtain electrolyte II; obtaining RGB information of electrolyte II, wherein the amount of pentavalent ion electrolyte is such that the blue channel value in the RGB information of electrolyte II is maximized, to obtain electrolyte III; dividing electrolyte III into two portions, with one portion serving as the catholyte and an acid solution serving as the anolyte, and performing constant current electrolysis to obtain electrolyte IV; introducing an oxidizing gas into electrolyte III to oxidize the divalent metal cations to trivalent cations to obtain electrolyte V; and mixing the other portion with electrolyte V in equal volumes. This repair method has excellent repair effects and can improve the utilization efficiency of the unbalanced battery electrolyte.

Description

Technical Field

[0001] The present invention relates to electrolyte repair, and in particular to a method for repairing an unbalanced battery electrolyte. Background Art

[0002] The single active material in the electrolyte of the all-vanadium redox flow battery (VRFB) can effectively avoid the cross-contamination problem caused by the migration of the positive and negative electrolytes of the flow battery; moreover, the all-vanadium redox flow battery has excellent safety because the electrolyte and the electrolyte reaction site (i.e., the electrodes) are separated from each other, making it a highly anticipated large-scale energy storage method. However, the ion exchange membrane used in the all-vanadium redox flow battery cannot guarantee the H + While passing through, it completely blocks the penetration of vanadium. Vanadium ions of different valence carry different numbers of bound water and have different diffusion rates in the proton exchange membrane, which will inevitably lead to an imbalance in the volume, concentration, and valence of the electrolyte of the all-vanadium flow battery. Its intuitive manifestation is the battery capacity decay. The capacity recovery of the unbalanced electrolyte is one of the bottleneck technologies that affects whether the all-vanadium flow battery can be applied on a large scale.

[0003] At present, the research on rebalancing of unbalanced electrolytes is mainly divided into complete rebalancing and partial rebalancing. Both complete remixing rebalancing and partial mixing rebalancing are considered from the perspective of restoring the volume and concentration of the electrolyte, and cannot solve the problems of oxidation imbalance and reduction imbalance of the electrolyte. However, in actual operation, the oxidation imbalance and reduction imbalance of the electrolyte will also lead to capacity loss of the battery.

[0004] Although some repair methods have been proposed in the prior art, there are problems such as complex repair processes and unsatisfactory repair effects. Therefore, there is an urgent need to provide a method for repairing an unbalanced electrolyte. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems of complex repair process and unsatisfactory repair effect of unbalanced electrolyte in the prior art, and to provide a method for repairing unbalanced battery electrolyte, which has good repair effect and can improve the utilization efficiency of unbalanced battery electrolyte.

[0006] In order to achieve the above object, the present invention provides a method for repairing an unbalanced battery electrolyte, comprising the following steps:

[0007] (1) mixing the anolyte and catholyte of the unbalanced cell to obtain electrolyte I;

[0008] configuring a pentavalent ion electrolyte of the metal cations contained in the electrolyte I;

[0009] (2) mixing the pentavalent ion electrolyte and the electrolyte I to obtain electrolyte II, obtaining RGB information of the electrolyte II, and using an amount of the pentavalent ion electrolyte so that the blue channel value in the RGB information of the electrolyte II is maximized, thereby obtaining electrolyte III;

[0010] (3) dividing the electrolyte III into two parts, using one part of the electrolyte III as the cathode electrolyte and the acid solution as the anode electrolyte, and performing constant current electrolysis to obtain electrolyte IV;

[0011] (4) introducing an oxidizing gas into the electrolyte IV to oxidize the metal divalent cations contained in the electrolyte IV into trivalent cations to obtain electrolyte V; and mixing another portion of electrolyte III with the electrolyte V in the same volume.

[0012] Preferably, in step (1), the total molar concentration of metal cations in the electrolyte I is determined to be C 总阳离子 The molar concentration of the acid radical ion is recorded as c 酸根离子 .

[0013] Preferably, in the pentavalent ion electrolyte, the molar concentration of the pentavalent cations of the metal is the same as the total molar concentration of the metal cations in the electrolyte I, and the molar concentration of the acid radical ions is the same as the molar concentration of the acid radical ions in the electrolyte I.

[0014] Preferably, the acid is sulfuric acid, the metal is vanadium metal, the pentavalent cation of the metal is a pentavalent cation of vanadium, the divalent cation of the metal is a divalent cation of vanadium, and the trivalent cation of the metal is a trivalent cation of vanadium.

[0015] Preferably, in step (2), the process of mixing the pentavalent ion electrolyte and the electrolyte I comprises: dripping the pentavalent ion electrolyte into the electrolyte I drop by drop.

[0016] Preferably, in step (2), the mixing conditions at least include: a rotation speed of 100-800 rpm.

[0017] Preferably, in step (2), the method for obtaining the RGB information of the electrolyte II includes: using MATLAB software to analyze the RGB information of the electrolyte II.

[0018] Preferably, in step (3), the molar concentration of the acid radical ions in the acid solution is the same as the molar concentration of the acid radical ions in the electrolyte I.

[0019] Preferably, the conditions for constant current electrolysis include at least: a current density of 30-60 mA / cm 2 , the electrolysis time is calculated according to formula (I),

[0020] t=aznF / I Formula (I);

[0021] Wherein, t is the electrolysis time, z is the number of electrons gained or lost in the reaction, F is the Faraday constant, n is the amount of tetravalent cation of the metal, I is the current, and a is the proportional coefficient, which is 1.1-1.5.

[0022] Preferably, in step (3), the volume ratio of the cathode electrolyte to the anode electrolyte is 1:1-1.5.

[0023] Preferably, in step (4), the oxidizing gas is air or oxygen.

[0024] Through the above technical solution, the present invention mixes the anolyte and catholyte of the unbalanced battery to obtain electrolyte I, then mixes electrolyte I with a pentavalent ion electrolyte containing the metal cations contained in electrolyte I to obtain electrolyte II. When the blue channel value in the RGB information of electrolyte II is the maximum, electrolyte III is obtained. At this time, electrolyte III is a pure tetravalent ion electrolyte of metal cations. This method can quickly and accurately determine the repair endpoint of the tetravalent ion electrolyte of metal cations, reduce repair errors, improve repair quality, and thus improve the utilization efficiency of the unbalanced battery electrolyte. In addition, a portion of electrolyte III is processed into a trivalent ion electrolyte of metal cations, namely electrolyte V. Electrolyte V and another portion of electrolyte III are mixed in equal volumes to obtain a 3.5-valent ion electrolyte of metal cations. The process is simple and the electrolyte quality is high.

[0025] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic structural diagram of an RGB information testing device provided by an embodiment of the present invention;

[0027] Figure 2 This is an endpoint determination diagram for the amount of pentavalent electrolyte added in Example 1;

[0028] Figure 3 is a UV-visible spectrum detection diagram of electrolyte III in Example 1;

[0029] Figure 4 This is a UV-visible spectrum detection diagram of the 3.5-valent electrolyte obtained in Example 1;

[0030] Figure 5 1 is the cyclic voltammogram of the electrolyte I in Example 1 and the repaired 3.5-valent electrolyte.

[0031] Description of Reference Numerals

[0032] 1. Shading mechanism; 2. Light source; 3. Dropper; 4. Beaker; 5. Image acquisition mechanism; 6. Image analysis mechanism. DETAILED DESCRIPTION

[0033] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0034] As mentioned above, the present invention provides a method for repairing an unbalanced battery electrolyte, comprising the following steps:

[0035] (1) mixing the anolyte and catholyte of the unbalanced cell to obtain electrolyte I;

[0036] configuring a pentavalent ion electrolyte of the metal cations contained in the electrolyte I;

[0037] (2) mixing the pentavalent ion electrolyte and the electrolyte I to obtain electrolyte II, obtaining RGB information of the electrolyte II, and using an amount of the pentavalent ion electrolyte so that the blue channel value in the RGB information of the electrolyte II is maximized, thereby obtaining electrolyte III;

[0038] (3) dividing the electrolyte III into two parts, using one part of the electrolyte III as the cathode electrolyte and the acid solution as the anode electrolyte, and performing constant current electrolysis to obtain electrolyte IV;

[0039] (4) introducing an oxidizing gas into the electrolyte IV to oxidize the metal divalent cations contained in the electrolyte IV into trivalent cations to obtain electrolyte V; and mixing another portion of electrolyte III with the electrolyte V in the same volume.

[0040] Chemical analysis (UV-visible spectroscopy and concentration determination) and cyclic voltammetry tests confirmed that the repaired electrolyte was a 3.5-valent electrolyte with good electrochemical activity. This indicates that this method is effective in repairing and can improve the utilization efficiency of the unbalanced electrolyte.

[0041] The present invention mixes the anolyte and catholyte of an unbalanced battery to obtain electrolyte I, which is then mixed with a pentavalent ion electrolyte containing the metal cations contained in electrolyte I to obtain electrolyte II. When the blue channel value in the RGB information of electrolyte II reaches its maximum, electrolyte III is obtained. At this time, electrolyte III is a pure tetravalent ion electrolyte containing metal cations. This method can quickly and accurately determine the repair endpoint of the tetravalent ion electrolyte containing metal cations, reduce repair errors, improve repair quality, and thereby improve the utilization efficiency of the unbalanced battery electrolyte. In addition, a portion of electrolyte III is processed into a trivalent ion electrolyte containing metal cations, namely electrolyte V. Electrolyte V and another portion of electrolyte III are mixed in equal volumes to obtain a 3.5-valent ion electrolyte containing metal cations. This method is simple in process and produces high-quality electrolytes.

[0042] According to the present invention, preferably, in the step (1), the total molar concentration of metal cations in the electrolyte I is determined to be C 总阳离子 The molar concentration of the acid radical ion is recorded as c 酸根离子 .

[0043] The total molar concentration of the metal cations in the above-mentioned electrolyte I can be measured by titration, and the reagent used in the titration can be a reagent conventionally used in the art to titrate the total molar concentration of the metal cations. Taking the metal cations in the electrolyte I as trivalent vanadium ions and tetravalent vanadium ions as an example, with reference to the national standard GBT8704.5-2020, the total concentration of trivalent vanadium ions and tetravalent vanadium ions in the solution is titrated by potentiometric titration, and with reference to the industry standard T / QAS 004-2019, the sulfate concentration in the solution is titrated by gravimetric method.

[0044] According to the present invention, preferably, in the pentavalent ion electrolyte, the molar concentration of the pentavalent cations of the metal is the same as the total molar concentration of the metal cations in the electrolyte I, and the molar concentration of the acid radical ions is the same as the molar concentration of the acid radical ions in the electrolyte I. The inventors have found that under this preferred embodiment, it is possible to ensure that the metal cation concentration and the acid radical ion concentration in the electrolyte after repair are the same as the total molar concentration of the metal cations and the acid radical concentration in the unbalanced electrolyte before repair, respectively, thereby avoiding the problem of excessive deviation of the metal cation concentration and the acid radical concentration in the electrolyte due to a large number of repairs.

[0045] According to the present invention, preferably, the acid is sulfuric acid, the metal is vanadium, the pentavalent cation of the metal is a pentavalent cation of vanadium, the divalent cation of the metal is a divalent cation of vanadium, and the trivalent cation of the metal is a trivalent cation of vanadium. The inventors have discovered that under this preferred embodiment, the repair method provided by the present invention has a good repair effect on all-vanadium redox flow batteries.

[0046] In the present invention, in step (1), the process of preparing a pentavalent ion electrolyte includes: dissolving vanadium sulfate in a sulfuric acid solution to obtain a metal tetravalent ion electrolyte, wherein the molar concentration of sulfate ions in the sulfuric acid solution is the same as the molar concentration of acid radical ions in the electrolyte I; placing the metal tetravalent ion electrolyte at the positive and negative electrodes of the flow battery, performing constant current charging, and when the anode electrolyte is pure yellow, the anode is the pentavalent ion electrolyte.

[0047] According to the present invention, preferably, in step (2), the process of mixing the pentavalent ion electrolyte and the electrolyte I includes: dripping the pentavalent ion electrolyte dropwise into the electrolyte I. The inventors have found that under this preferred embodiment, the accuracy of obtaining a pure tetravalent ion electrolyte in which the electrolyte III is a metal cation can be improved, the repair error can be reduced, the repair quality can be improved, and the utilization efficiency of the unbalanced battery electrolyte can be further improved.

[0048] In the present invention, in step (2), during the mixing of the pentavalent ion electrolyte and the electrolyte I, the chemical reaction that occurs is as follows:

[0049] V 3+ +VO2 + →2VO 2+ .

[0050] According to the present invention, in order to further improve the repair quality of the unbalanced battery electrolyte, preferably, in the step (2), the mixing conditions include at least: a rotation speed of 100-800 rpm, specifically 100 rpm, 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, or any value between the foregoing two values.

[0051] According to the present invention, preferably, in the step (2), the method for obtaining the RGB information of the electrolyte II includes: using MATLAB software to analyze the RGB information of the electrolyte II.

[0052] In the present invention, an RGB information testing device can be used to obtain the RGB information of the electrolyte II, such as Figure 1As shown, the RGB information measuring device includes a shading mechanism 1, a light source 2, an image acquisition mechanism 5 and an image analysis mechanism 6. The light source 2 is arranged inside the shading mechanism 1. One end of the image acquisition mechanism 5 is connected to the shading mechanism 1 and the other end is connected to the image analysis mechanism 6. The shading mechanism 1 can be a black shading box with a white inner wall; the light source 2 can be an LED lamp, and the light source 2 is arranged on the top inner wall of the shading mechanism 1. The image acquisition mechanism 5 can adopt a shooting device conventionally selected in the field, such as a camera, an optical sensor, etc. The image analysis mechanism 6 can be a computer installed with MATLAB software. The inventors found that under this preferred embodiment, the RGB information of the electrolyte II can be monitored online, thereby improving the accuracy of the RGB information measurement.

[0053] According to the present invention, the working process of the RGB information testing device includes: placing electrolyte I in a beaker 4, using a dropper 3 to drip a pentavalent ion electrolyte into electrolyte I to obtain electrolyte II, obtaining an image of electrolyte II through an image acquisition mechanism 5, storing the image in an image analysis mechanism 6, using MATLAB software to perform image processing, first cropping the image, then reducing noise, and finally extracting the RGB information of the image.

[0054] In the present invention, a conventional code for obtaining image RGB information can be used to obtain RGB information of electrolyte II, where the RGB information includes a blue channel value, a red channel value, and a green channel value. According to the present invention, in order to further reduce the deviation of the acid radical ion concentration in the repaired electrolyte, preferably, in step (3), the molar concentration of the acid radical ions in the acid solution is the same as the molar concentration of the acid radical ions in the mixed electrolyte I.

[0055] According to the present invention, preferably, the conditions for constant current electrolysis include at least: a current density of 30-60 mA / cm 2 , specifically 30mA / cm 2 , 40mA / cm 2 , 50mA / cm 2 、60mA / cm 2 , or any value between the above two values; the electrolysis time is calculated according to formula (I);

[0056] t=aznF / I Formula (I);

[0057] Where t is the electrolysis time, z is the number of electrons gained or lost in the reaction, F is the Faraday constant, n is the amount of tetravalent metal cations, I is the current, and a is the proportionality factor, which is 1.1-1.5. Controlling the current density and electrolysis time within the above ranges can further improve the remediation effect of the electrolyte.

[0058] In the present invention, as n=cV, the electrolysis time can also be obtained according to formula (II);

[0059] t=azcVF / I Formula (II);

[0060] Where c is the molar concentration of the tetravalent metal cation, and V is the volume of the electrolyte.

[0061] In the present invention, the units of the above parameters are all international standard units, the electrolysis time is s, the unit of mole number is mol, the unit of current is ampere, the unit of molar concentration is mol / L, and the unit of volume is L.

[0062] According to the present invention, preferably, in step (3), the volume ratio of the catholyte to the anolyte is 1:1-1.5, specifically 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, or any value between the two aforementioned values. The inventors have found that under this preferred embodiment, the repair effect of the electrolyte can be further improved.

[0063] According to the present invention, in order to further improve the oxidation effect of oxidizing metal divalent cations to trivalent cations, preferably, in step (4), the oxidizing gas is air or oxygen. In order to reduce production costs, the oxidizing gas is preferably air.

[0064] In the present invention, there is no particular limitation on the flow rate of the oxidizing gas, and the flow rate of the oxidizing gas can be 5-10 cm 3 / h.

[0065] For example, when the oxidizing gas is air, the electrolyte IV can be left to stand in the air for 24-36 hours.

[0066] According to a particularly preferred embodiment of the present invention, a method for repairing an unbalanced battery electrolyte comprises the following steps:

[0067] (1) The anolyte and catholyte of the unbalanced cell are mixed to obtain electrolyte I, and the total molar concentration of metal cations in the electrolyte I is determined to be C 总阳离子 The molar concentration of the acid radical ion is recorded as c 酸根离子 ; configuring a pentavalent ion electrolyte of the metal cations contained in the electrolyte I, wherein the molar concentration of the pentavalent ion of the metal is the same as the total molar concentration of the metal cations in the electrolyte I, and the molar concentration of the acid radical ions is the same as the molar concentration of the acid radical ions in the electrolyte I;

[0068] (2) dripping the pentavalent ion electrolyte dropwise into the electrolyte I at a rotation speed of 100-800 rpm to obtain electrolyte II, obtaining RGB information of the electrolyte II, and analyzing the RGB information of the electrolyte II using MATLAB software; the amount of the pentavalent ion electrolyte is such that the blue channel value in the RGB information of the electrolyte II is maximized, thereby obtaining electrolyte III;

[0069] (3) The electrolyte III is divided into two parts, wherein one part of the electrolyte III is used as the cathode electrolyte and the acid solution is used as the anode electrolyte, and constant current electrolysis is performed under the condition that the volume ratio of the cathode electrolyte to the anode electrolyte is 1:1-1.5 to obtain electrolyte IV; the molar concentration of the acid radical ions in the acid solution is the same as the molar concentration of the acid radical ions in the mixed electrolyte I; the conditions of the constant current electrolysis include at least: a current density of 30-60 mA / cm 2 , the electrolysis time is calculated according to formula (I);

[0070] t=aznF / I Formula (I);

[0071] Wherein, t is the electrolysis time, z is the number of electrons gained or lost in the reaction, F is the Faraday constant, n is the amount of tetravalent cation of the metal, I is the current, and a is the proportional coefficient, which is 1.1-1.5;

[0072] (4) introducing an oxidizing gas into the electrolyte IV to oxidize the divalent metal cations contained in the electrolyte IV into trivalent cations to obtain an electrolyte V; mixing another portion of the electrolyte III with the electrolyte V in equal volumes; the oxidizing gas is air or oxygen;

[0073] The acid is sulfuric acid, the metal is vanadium metal, the pentavalent cation of the metal is a pentavalent cation of vanadium, the divalent cation of the metal is a divalent cation of vanadium, and the trivalent cation of the metal is a trivalent cation of vanadium.

[0074] The method for repairing an unbalanced battery electrolyte provided by the above particularly preferred embodiment can quickly and accurately determine the repair endpoint of a tetravalent metal cation electrolyte, thereby reducing repair errors, improving repair quality, and thereby increasing the utilization efficiency of the unbalanced battery electrolyte.

[0075] The present invention will be described in detail below through examples. The RGB information measurement device includes a light shielding mechanism 1, a light source 2, an image acquisition mechanism 5, and an image analysis mechanism 6. The light source 2 is disposed within the light shielding mechanism 1. One end of the image acquisition mechanism 5 is connected to the light shielding mechanism 1, and the other end is connected to the image analysis mechanism 6. Unless otherwise specified, the following raw materials were commercially available.

[0076] Example 1

[0077] (1) The unbalanced electrolytes were mixed to obtain 100 mL of electrolyte I, and the vanadium ion concentration in the electrolyte I was titrated to 1.69 mol / L and the sulfate ion concentration was 4 mol / L;

[0078] (2) A quaternary electrolyte with a vanadium ion concentration of 1.69 mol / L and a sulfate concentration of 4 mol / L was prepared, and the RGB information of the quaternary electrolyte was obtained. The RGB information was analyzed using MATLAB software to obtain a blue channel value of 204.13; the electrolyte I was placed in an RGB information test device (such as Figure 1 As shown in FIG, a pentavalent electrolyte having a vanadium ion concentration of 1.69 mol / L and a sulfate concentration of 4 mol / L was added dropwise (0.1 mL per drop) to obtain the RGB information of electrolyte II. The blue channel value in the RGB information was analyzed using MATLAB software. When the blue channel value in the RGB information of electrolyte II was the largest, that is, it reached more than 95% of the blue channel value of the tetravalent electrolyte, see Figure 2 , stop adding the pentavalent electrolyte to obtain electrolyte III;

[0079] (3) Place half the volume of electrolyte III in the cathode compartment of the electrolytic cell, and place dilute sulfuric acid with a sulfuric acid concentration of 4 mol / L in the anode compartment of the electrolytic cell. At this time, the volume ratio of the cathode electrolyte to the anode electrolyte is 1:1, and the electrode area is 9 cm 2 , then at 40mA / cm 2 Electrolyze for 13 h at a current density of , to obtain electrolyte IV;

[0080] The electrolysis time is calculated as follows:

[0081] t=aznF / I=azcvF / I=a×1×0.07×1.695×96485 / 0.04×9=1.4×1×0.07×1.69×96485 / 0.36=44388.46s=12.33h;

[0082] (4) passing air into the electrolyte in the cathode chamber of the electrolytic cell to oxidize all the divalent vanadium ions into trivalent vanadium ions, thereby obtaining electrolyte V;

[0083] (5) Electrolyte V is mixed with the other half volume of electrolyte III in step (3) in equal volumes to obtain a 3.5-valent electrolyte.

[0084] Test Example 1

[0085] The electrolyte III obtained in step (2) of Example 1 was subjected to UV-visible spectroscopy analysis to obtain Figure 3 .Depend on Figure 3It can be seen that there is an absorption peak of tetravalent vanadium ions at around 780nm, and there is no absorption peak of trivalent vanadium ions at around 600nm and 400nm, which proves that there are tetravalent vanadium ions in the solution, but no trivalent vanadium ions; when compared with the UV-visible light analysis curve of the diluted pentavalent electrolyte at 335nm, no absorption peak was found, so the solution does not contain pentavalent vanadium ions, but only tetravalent vanadium ions.

[0086] Test Example 2

[0087] The 3.5-valent electrolyte obtained in Example 1 was subjected to UV-visible spectroscopy analysis to obtain Figure 4 .Depend on Figure 4 It can be seen that there is an absorption peak of tetravalent vanadium ion at around 780nm, and absorption peaks of trivalent vanadium ion at around 600nm and 400nm, proving the presence of trivalent and tetravalent vanadium ions in the solution. Although UV-visible spectroscopy detection of pentavalent and divalent vanadium ions is relatively unstable, trivalent and pentavalent vanadium ions cannot coexist in the same solution, and tetravalent vanadium ions cannot coexist with divalent vanadium ions. Therefore, it can be determined that trivalent and tetravalent vanadium ions are present in the prepared electrolyte, but pentavalent and divalent vanadium ions are absent.

[0088] Test Example 3

[0089] The concentrations of trivalent vanadium ions and tetravalent vanadium ions in the repaired 3.5-valent electrolyte obtained in Example 1 were titrated using an automatic potentiometric titrator to obtain the values ​​shown in Table 1.

[0090] Table 1

[0091] c(trivalent vanadium ion) c(quaternary vanadium ion) c(trivalent vanadium ion):c(quaternary vanadium ion) 0.7999 0.8001 0.9997

[0092] From the results in Table 1, it can be seen that c(trivalent vanadium ion):c(quaternary vanadium ion) = 0.9997, which is in line with the national standard GB / T37204-2018, and the ratio of trivalent and quadrivalent vanadium ions in 3.5-valent electrolyte is 1±0.1, indicating that the repair method provided by this method has a good repair effect and can improve the utilization efficiency of the unbalanced battery electrolyte.

[0093] Test Example 4

[0094] Cyclic voltammetry was performed on the unbalanced electrolyte and the repaired electrolyte (the 3.5-valent electrolyte obtained in Example 1) in the same three-electrode system at 0-1.7 V and a scan rate of 40 mV / s, and the results were as follows: Figure 5 .

[0095] Depend on Figure 5It can be seen that after the electrolyte was repaired, the oxidation peak current density and reduction peak current density increased, indicating that the electrolyte's electrochemical activity increased; the area of ​​the redox peak increased, indicating that the electrochemical reaction capacity in the electrolyte increased; the difference in the height of the oxidation peak and the reduction peak was very small, indicating that the reversibility of the electrolyte was significantly improved. Therefore, compared with the unbalanced electrolyte, the electrochemical activity, electrochemical reaction capacity, and reversibility of the repaired electrolyte were significantly increased, demonstrating the feasibility of this repair method.

[0096] Example 2

[0097] The unbalanced electrolyte was repaired according to the method of Example 1, except that the volume ratio of the cathode electrolyte to the anode electrolyte in step (3) was replaced with 1:2.

[0098] Test Example 5

[0099] The concentrations of trivalent vanadium ions and tetravalent vanadium ions in the repaired 3.5-valent electrolyte obtained in Example 3 were titrated using an automatic potentiometric titrator to obtain the values ​​shown in Table 2.

[0100] Table 2

[0101] c(trivalent vanadium ion) c(quaternary vanadium ion) c(trivalent vanadium ion):c(quaternary vanadium ion) 0.813 0.877 0.927

[0102] From the results in Table 2, it can be seen that c(trivalent vanadium ion):c(quaternary vanadium ion) = 0.927 is in line with the national standard GB / T37204-2018, which stipulates that the ratio of trivalent and quadrivalent vanadium ions in 3.5-valent electrolytes is 1±0.1. This shows that the repair method provided by this method has a good repair effect and can improve the utilization efficiency of the unbalanced battery electrolyte.

[0103] Comparative Example

[0104] The unbalanced electrolyte was repaired according to the method of Example 1, and the total vanadium concentration of the mixed electrolyte I was 1.6 mol / L, except that step (2) was replaced by:

[0105] (2) After the concentration of trivalent vanadium ions in the mixed electrolyte I is obtained by titration, the volume of pentavalent vanadium electrolyte having the same total vanadium concentration as the mixed electrolyte I is added, and the calculation formula is:

[0106] V=c 3价钒离子 ×V I / c 5价钒离子 ;

[0107] That is, a pentavalent electrolyte with a volume of V is added to obtain electrolyte II.

[0108] Test Example 6

[0109] The concentrations of trivalent vanadium ions and tetravalent vanadium ions in the repaired 3.5-valent electrolyte obtained in the comparative example were titrated using an automatic potentiometric titrator to obtain Table 3.

[0110] Table 3

[0111] c(trivalent vanadium ion) c(quaternary vanadium ion) c(trivalent vanadium ion):c(quaternary vanadium ion) 0.771 0.829 0.9300

[0112] From the results in Table 3, it can be seen that c(trivalent vanadium ion):c(quaternary vanadium ion)=0.9300, which is in line with the national standard GB / T37204-2018 that the ratio of trivalent and quadrivalent vanadium ions in 3.5-valent electrolyte is 1±0.1.

[0113] As can be seen from the titration results, even if the 3.5-valent electrolyte in the comparative example meets national standards, the degree of C (3-valent vanadium ion): C (4-valent vanadium ion) deviation from 1 is large, and the degree of deviation directly affects the quality of the electrolyte. This is because, although the volume of the pentavalent electrolyte added by calculation is accurate, mechanical errors (such as pipetting errors, titration errors, etc.) cannot be avoided, and by measuring the RGB information of the electrolyte II during the addition of the pentavalent electrolyte, the internal ionic valence of the solution can be accurately judged, the error can be effectively reduced, and the resulting electrolyte quality is better.

[0114] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for repairing an unbalanced battery electrolyte, characterized in that: The steps include: (1) mixing the anolyte and catholyte of the unbalanced cell to obtain electrolyte I; configuring a pentavalent ion electrolyte of the metal cations contained in the electrolyte I; (2) mixing the pentavalent ion electrolyte and the electrolyte I to obtain electrolyte II, obtaining RGB information of the electrolyte II, and using an amount of the pentavalent ion electrolyte so that the blue channel value in the RGB information of the electrolyte II is maximized, thereby obtaining electrolyte III; (3) dividing the electrolyte III into two parts, wherein one part of the electrolyte III is used as the cathode electrolyte and the acid solution is used as the anode electrolyte, and constant current electrolysis is performed to obtain electrolyte IV; (4) introducing an oxidizing gas into the electrolyte IV to oxidize the metal divalent cations contained in the electrolyte IV into trivalent cations to obtain an electrolyte V; and mixing another portion of the electrolyte III with the electrolyte V in equal volumes; In the step (1), the total molar concentration of metal cations in the electrolyte I is determined to be C 总阳离子 The molar concentration of the acid radical ion is recorded as c 酸根离子 ; In the pentavalent ion electrolyte, the molar concentration of the pentavalent metal cations is the same as the total molar concentration of the metal cations in the electrolyte I, and the molar concentration of the acid radical ions is the same as the molar concentration of the acid radical ions in the electrolyte I; the acid in the acid solution is sulfuric acid, the metal is vanadium metal, the pentavalent metal cations are pentavalent cations of vanadium, the divalent metal cations are divalent cations of vanadium, and the trivalent metal cations are trivalent cations of vanadium.

2. The repair method according to claim 1, characterized in that: In the step (2), the process of mixing the pentavalent ion electrolyte and the electrolyte I comprises: dripping the pentavalent ion electrolyte into the electrolyte I drop by drop; In step (2), the mixing conditions include at least a rotation speed of 100-800 rpm.

3. The repair method according to claim 2, characterized in that: In the step (2), the method for obtaining the RGB information of the electrolyte II includes: using MATLAB software to analyze the RGB information of the electrolyte II.

4. The repair method according to claim 1, characterized in that: In step (3), the molar concentration of the acid radical ions in the acid solution is the same as the molar concentration of the acid radical ions in the electrolyte I.

5. The repair method according to claim 4, characterized in that: The conditions of the constant current electrolysis include at least: a current density of 30-60 mA / cm 2 , the electrolysis time is calculated according to formula (I), t=aznF / I formula (I); Wherein, t is the electrolysis time, z is the number of electrons gained or lost in the reaction, F is the Faraday constant, n is the amount of tetravalent cation of the metal, I is the current, and a is the proportional coefficient, which is 1.1-1.

5.

6. The repair method according to claim 4, characterized in that: In the step (3), the volume ratio of the cathode electrolyte to the anode electrolyte is 1:1-1.

5.

7. The repair method according to claim 1, characterized in that: In step (4), the oxidizing gas is air or oxygen.

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