Method for regenerating electrolyte of failure vanadium battery
阅读说明：本技术 一种失效钒电池电解液再生的方法 (Method for regenerating electrolyte of failure vanadium battery ) 是由 刘涛 丁木清 张一敏 薛楠楠 刘红 于 2020-04-03 设计创作，主要内容包括：本发明涉及一种失效钒电池电解液再生的方法。其技术方案是：将失效钒电池正极电解液与失效钒电池负极电解液混合,得电解液Ⅰ；再加入钒化合物、支持电解质和去离子水,搅拌,固液分离,收集液相,得电解液Ⅱ。将阳极复合电极和阴极复合电极依次置于电容去离子装置的正极端和负极端,在直流电压为0.5～3V条件下将电解液Ⅱ循环泵入电容去离子装置中,即得电解液Ⅲ；将电解液Ⅲ置于电解槽负极室,向电解槽正极室加入与所述电解液Ⅲ的酸度相同的硫酸溶液,在电流为1～5A条件下恒流电解至电解液价态为3.5价,即得再生电解液。本发明工艺简单、环境友好、成本低和便于规模化应用,再生电解液具有良好的稳定性和电化学性能,达到正常使用要求。(The invention relates to a method for regenerating an electrolyte of a failure vanadium redox battery. The technical scheme is as follows: mixing the failure vanadium battery positive electrolyte with the failure vanadium battery negative electrolyte to obtain an electrolyte I; and adding a vanadium compound, a supporting electrolyte and deionized water, stirring, carrying out solid-liquid separation, and collecting a liquid phase to obtain an electrolyte II. Placing the anode composite electrode and the cathode composite electrode in sequence at the positive end and the negative end of the capacitive deionization device, and circularly pumping the electrolyte II into the capacitive deionization device under the condition that the direct-current voltage is 0.5-3V to obtain an electrolyte III; and (3) placing the electrolyte III in an electrolytic cell negative electrode chamber, adding a sulfuric acid solution with the same acidity as the electrolyte III into an electrolytic cell positive electrode chamber, and performing constant-current electrolysis under the condition that the current is 1-5A until the valence state of the electrolyte is 3.5, thus obtaining the regenerated electrolyte. The method has the advantages of simple process, environmental friendliness, low cost and convenience for large-scale application, and the regenerated electrolyte has good stability and electrochemical performance and meets the normal use requirement.)
1. A method for regenerating an electrolyte of a failed vanadium battery is characterized by comprising the following specific steps:
mixing the positive electrolyte of the failed vanadium redox battery with the negative electrolyte of the failed vanadium redox battery to obtain an electrolyte I; adding a vanadium compound, a supporting electrolyte and deionized water into the electrolyte I, stirring for 0.5-12 h, carrying out solid-liquid separation, and collecting a liquid phase to obtain an electrolyte II; wherein:
the amount Mv of the vanadium species added to the vanadium compound
Mv＝CV2×V2－CVⅠ×V1(1)
The amount M of the substance of hydrogen ions added to the supporting electrolyteH2
MH2＝CH2×V2－CH1×V1(2)
In the formulae (1) and (2):
CVⅠthe concentration of vanadium ions in the electrolyte I is shown, mol/L;
CH1represents the hydrogen ion concentration in the electrolyte I, mol/L;
V1represents the volume of electrolyte i, L;
CV2represents the concentration of vanadium ions in the regenerated electrolyte, mol/L;
CH2represents the hydrogen ion concentration in the regenerated electrolyte, mol/L;
V2indicating the volume of regenerated electrolyte, L;
step two, firstly, mixing a carbon material, anion exchange resin, a binder and an organic solvent according to the mass ratio of 1: 0.5-5: 0.05-0.5: 2-10, mixing the carbon material, the anion exchange resin, the binder and the organic solvent, and stirring for 2-6 hours to obtain a mixed solution I; uniformly spraying or coating the mixed solution I on a graphite felt electrode, and drying at 40-75 ℃ to obtain an anode composite electrode;
the anion exchange resin is more than one of primary amino anion exchange resin, secondary amino anion exchange resin and tertiary amino anion exchange resin; the particle size of the anion exchange resin is less than 74 mu m and accounts for 60-85 wt%;
mixing a carbon material, a cation exchange resin, a binder and an organic solvent according to the mass ratio of 1: 0.5-5: 0.05-0.5: 2-10, mixing the carbon material, the cation exchange resin, the binder and the organic solvent, and stirring for 2-6 hours to obtain a mixed solution II; uniformly spraying or coating the mixed solution II on a graphite felt electrode, and drying at 40-75 ℃ to obtain a cathode composite electrode;
the cation exchange resin is more than one of sulfonic cation exchange resin, carboxyl cation exchange resin, thiourea cation exchange resin and imine diacetic cation exchange resin; the particle size of the cation exchange resin is less than 74 mu m and accounts for 60-85 wt%;
step four, sequentially placing the anode composite electrode and the cathode composite electrode at the positive end and the negative end of the capacitive deionization device, switching on a direct-current power supply, setting the voltage to be 0.5-3V, circularly pumping the electrolyte II into the capacitive deionization device, wherein the flow of the electrolyte II passing through the composite electrode per square meter is 5-40L/min, and the circulation time is 0.5-6 h, so as to obtain an electrolyte III;
the composite electrode is the anode composite electrode and the cathode composite electrode;
putting the electrolyte III in a negative electrode chamber of an electrolytic cell, and adding a sulfuric acid solution into a positive electrode chamber of the electrolytic cell, wherein the acidity of the sulfuric acid solution is the same as that of the electrolyte III; and then switching on a power supply, and carrying out constant-current electrolysis under the condition that the current is 1-5A until the valence state of the electrolyte is 3.5, thus obtaining the regenerated electrolyte.
2. The method of regenerating a spent vanadium battery electrolyte according to claim 1, wherein the supporting electrolyte is one or more of sulfuric acid, hydrochloric acid, phosphoric acid, hydrofluoric acid, methanesulfonic acid, taurine and sulfamic acid.
3. The method of claim 1, wherein the vanadium compound is one or more of vanadium pentoxide, vanadium trioxide and vanadium dioxide; the purity of the vanadium compound is more than or equal to 99.5 percent.
4. The method for regenerating the spent vanadium battery electrolyte according to claim 1, wherein the carbon material in the second step and the third step is one or more of activated carbon, graphene, carbon nanotubes and acetylene black; the carbon material has a particle size of less than 74 μm and accounts for 60-85 wt%.
5. The method for regenerating the electrolyte of the failed vanadium redox battery according to claim 1, wherein the binder in the second step and the third step is one or more of polytetrafluoroethylene, polyvinylidene fluoride and polyvinyl alcohol.
6. The method for regenerating the electrolyte of the failed vanadium redox battery according to claim 1, wherein the organic solvent in the second step and the third step is one of ethanol, acetone, dimethylacetamide and dimethylformamide.
Technical Field
The invention belongs to the technical field of vanadium battery electrolyte. In particular to a method for regenerating the electrolyte of a failure vanadium redox battery.
Background
The vanadium redox battery has the advantages of long service life, low operation and maintenance cost, high reliability, strong safety, easiness in large-scale application and the like, and is widely applied. The vanadium battery electrolyte is an energy storage active substance of the vanadium battery as an important component of the vanadium battery, and the performance of the vanadium battery electrolyte directly determines the performance of the vanadium battery. With continuous charging and discharging of the vanadium battery, phenomena of vanadium ion migration, pentavalent vanadium ion precipitation in the positive electrolyte, divalent vanadium ion oxidation in the negative electrolyte and the like can be generated between the positive electrolyte and the negative electrolyte, so that the concentration and valence state of vanadium ions in the positive electrolyte and the negative electrolyte are unbalanced. In addition, in the operation process of the vanadium redox battery, impurity ions in the electrolyte can be accumulated continuously, so that the performance of the electrolyte can not meet the application requirement, and a new electrolyte needs to be replaced, thereby generating the failure vanadium redox battery electrolyte. Therefore, the research and development of the regeneration method of the electrolyte of the failed vanadium redox battery has very important significance for the industrialization and large-scale development of the vanadium redox battery.
At present, the regeneration method of the electrolyte of the failure vanadium battery is mainly to dilute the electrolyte, adjust the pH value of the electrolyte, precipitate vanadium, obtain solid vanadium compounds such as vanadium pentoxide or vanadyl sulfate and the like, and then dissolve the solid vanadium compounds to prepare the electrolyte. The process is complicated, the vanadium recovery rate is low, the electrolyte regeneration cost is high, and the environment is polluted by waste water and waste gas generated.
The patent technology of 'a regeneration method of a sulfuric acid system failure vanadium electrolyte' (CN109360997A) is to add a tetravalent vanadium electrolyte or a trivalent vanadium electrolyte and water into the failure vanadium battery electrolyte to obtain a regenerated electrolyte; the patent technology of 'a regeneration method of a failure vanadium battery electrolyte' (CN109065906A) is to add vanadium trichloride or vanadyl dichloride, hydrochloric acid and water into the failure electrolyte to obtain a regenerated electrolyte; the patent technology of 'a method for regenerating vanadium electrolyte by using negative electrolyte of a failed vanadium battery' (CN109461948A) comprises the steps of adding vanadium pentoxide and sulfuric acid into the negative electrolyte, carrying out solid-liquid separation after reaction, collecting liquid phase, and adding water for dilution to obtain regenerated electrolyte; the patent technology of 'method for regenerating vanadium electrolyte by using positive electrolyte of failed vanadium battery' (CN109148911A) adds vanadium dichloride, hydrochloric acid and water into the positive electrolyte to obtain regenerated electrolyte. Although the process has high vanadium recovery rate and simple operation, the problem of unbalanced valence state of vanadium ions in the electrolyte of the ineffective vanadium battery can only be solved.
In summary, the regeneration method of the current failure vanadium battery electrolyte generally adopts a mode of diluting and adjusting pH to precipitate vanadium to prepare a solid vanadium compound, and then dissolving the solid vanadium compound to prepare the electrolyte, so that the problems of complex process, high treatment cost, difficult vanadium recovery and utilization rate reaching 100%, environmental pollution caused by generated wastewater and the like exist; the method of adding the high-purity vanadium compound has the problem that the failure of the electrolyte caused by the influence of impurity ions cannot be solved.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides the regeneration method of the electrolyte of the failed vanadium battery, which has the advantages of simple process, high vanadium recovery and utilization rate, environmental friendliness, low treatment cost and convenience for large-scale application.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
mixing the positive electrolyte of the failed vanadium redox battery with the negative electrolyte of the failed vanadium redox battery to obtain an electrolyte I; adding a vanadium compound, a supporting electrolyte and deionized water into the electrolyte I, stirring for 0.5-12 h, carrying out solid-liquid separation, and collecting a liquid phase to obtain an electrolyte II; wherein:
the amount Mv of the vanadium species added to the vanadium compound
Mv＝CV2×V2－CVⅠ×V1(1)
The amount M of the substance of hydrogen ions added to the supporting electrolyteH2
MH2＝CH2×V2－CH1×V1(2)
In the formulae (1) and (2):
CVⅠthe concentration of vanadium ions in the electrolyte I is shown, mol/L;
CH1represents the hydrogen ion concentration in the electrolyte I, mol/L;
V1represents the volume of electrolyte i, L;
CV2represents the concentration of vanadium ions in the regenerated electrolyte, mol/L;
CH2represents the hydrogen ion concentration in the regenerated electrolyte, mol/L;
V2indicating the volume of regenerated electrolyte, L.
Step two, firstly, mixing a carbon material, anion exchange resin, a binder and an organic solvent according to the mass ratio of 1: 0.5-5: 0.05-0.5: 2-10, mixing the carbon material, the anion exchange resin, the binder and the organic solvent, and stirring for 2-6 hours to obtain a mixed solution I; and uniformly spraying or coating the mixed solution I on a graphite felt electrode, and drying at 40-75 ℃ to obtain the anode composite electrode.
The anion exchange resin is more than one of primary amino anion exchange resin, secondary amino anion exchange resin and tertiary amino anion exchange resin; the particle size of the anion exchange resin is less than 74 mu m and accounts for 60-85 wt%.
Mixing a carbon material, a cation exchange resin, a binder and an organic solvent according to the mass ratio of 1: 0.5-5: 0.05-0.5: 2-10, mixing the carbon material, the cation exchange resin, the binder and the organic solvent, and stirring for 2-6 hours to obtain a mixed solution II; and uniformly spraying or coating the mixed solution II on a graphite felt electrode, and drying at 40-75 ℃ to obtain the cathode composite electrode.
The cation exchange resin is more than one of sulfonic cation exchange resin, carboxyl cation exchange resin, thiourea cation exchange resin and imine diacetic cation exchange resin; the particle size of the cation exchange resin is less than 74 mu m and accounts for 60-85 wt%.
And fourthly, sequentially placing the anode composite electrode and the cathode composite electrode at the positive end and the negative end of the capacitive deionization device, switching on a direct-current power supply, setting the voltage to be 0.5-3V, and circularly pumping the electrolyte II into the capacitive deionization device, wherein the flow of the electrolyte II passing through the composite electrode per square meter is 5-40L/min, and the circulation time is 0.5-6 h, so that the electrolyte III is obtained.
The composite electrode is the anode composite electrode and the cathode composite electrode.
Putting the electrolyte III in a negative electrode chamber of an electrolytic cell, and adding a sulfuric acid solution into a positive electrode chamber of the electrolytic cell, wherein the acidity of the sulfuric acid solution is the same as that of the electrolyte III; and then switching on a power supply, and carrying out constant-current electrolysis under the condition that the current is 1-5A until the valence state of the electrolyte is 3.5, thus obtaining the regenerated electrolyte.
The supporting electrolyte is more than one of sulfuric acid, hydrochloric acid, phosphoric acid, hydrofluoric acid, methanesulfonic acid, taurine and sulfamic acid.
The vanadium compound is more than one of vanadium pentoxide, vanadium trioxide and vanadium dioxide; the purity of the vanadium compound is more than or equal to 99.5 percent.
The carbon material in the second step and the third step is more than one of activated carbon, graphene, carbon nano tubes and acetylene black; the carbon material has a particle size of less than 74 μm and accounts for 60-85 wt%.
The binder in the second step and the third step is more than one of polytetrafluoroethylene, polyvinylidene fluoride and polyvinyl alcohol.
The organic solvent in the second step and the third step is one of ethanol, acetone, dimethylacetamide and dimethylformamide.
Compared with the prior art, the method has the following positive effects:
1. the method comprises the steps of adding a vanadium compound, a supporting electrolyte and deionized water into the electrolyte of the failed vanadium battery, adjusting the concentration and the acidity of vanadium ions, then preparing a cathode composite electrode by using cation exchange resin, preparing an anode composite electrode by using anion exchange resin, adsorbing and removing impurity ions in the electrolyte of the failed vanadium battery, finally electrolyzing, and adjusting the valence state of the vanadium ions of the regenerated electrolyte to be 3.5, so that the regenerated electrolyte is obtained, wherein the vanadium concentration of the regenerated electrolyte is 1-3 mol/L, the hydrogen ion concentration is 4-12 mol/L, the concentration and the acidity of the vanadium ions meet the requirements of normal use, the content of the impurity ions in the regenerated electrolyte is lower than 100 mg/L, and the valence state of the vanadium ions is stable 3.5, so that the regenerated electrolyte has good electrochemical performance and extremely high stability.
2. The method for regenerating the electrolyte of the failed vanadium battery not only avoids the problem that the electrolyte of the failed vanadium battery is firstly precipitated to prepare the solid vanadium compound, but also avoids the existing complex process for preparing the electrolyte by dissolving the solid vanadium compound. The capacitor deionization device and the electrolysis process are both low voltage and low current, the treatment energy consumption is low, no chemical agent is required to be added, and the treatment cost is low. The method firstly adds the vanadium compound, the supporting electrolyte and the deionized water into the electrolyte (namely the electrolyte I) of the failure vanadium battery to adjust the concentration and the acidity of the vanadium, then removes impurity ions by adopting a capacitance deionization method, and finally adjusts the valence state of the vanadium by adopting an electrolysis method without complex processes and equipment for adjusting the concentration, the acidity, the valence state of the vanadium and removing impurities.
According to the invention, electrochemical tests show that the electrolyte of the failure vanadium battery has poor electrochemical reversibility and severe oxygen and hydrogen evolution side reactions; according to the invention, electrochemical tests show that the regenerated electrolyte prepared from the spent vanadium battery electrolyte obviously improves the electrochemical reversibility of the regenerated electrolyte, obviously reduces oxygen evolution and hydrogen evolution side reactions, and obviously improves the electrochemical performance. The regenerated electrolyte prepared by the invention is loaded into a vanadium battery charging and discharging test system, and is subjected to charging and discharging circulation for 500 times: the coulomb efficiency is 90-95%; the energy efficiency is 70-76%.
Therefore, the method has the characteristics of simple process, high vanadium recovery and utilization rate, environmental friendliness, low treatment cost and convenience for large-scale application, and the concentration, valence state and acidity of the vanadium ions in the regenerated electrolyte prepared by the method not only meet the requirements of normal use, but also have good stability and electrochemical performance.
Drawings
FIG. 1 is a cyclic voltammogram of a spent vanadium battery electrolyte employed in the present invention;
figure 2 is a cyclic voltammogram of a regenerated electrolyte prepared with the spent vanadium battery electrolyte shown in figure 1.
Detailed Description
The invention is further described with reference to the following figures and detailed description, without limiting its scope.
In order to avoid repetition, the materials related to this specific embodiment are described in a unified manner, which is not described in the embodiments again:
the anion exchange resin is more than one of primary amine anion exchange resin, secondary amine anion exchange resin and tertiary amine anion exchange resin; the particle size of the anion exchange resin is less than 74 mu m and accounts for 60-85 wt%.
The cation exchange resin is more than one of sulfonic cation exchange resin, carboxyl cation exchange resin, thiourea cation exchange resin and imine diacetic cation exchange resin; the particle size of the cation exchange resin is less than 74 mu m and accounts for 60-85 wt%.
The supporting electrolyte is more than one of sulfuric acid, hydrochloric acid, phosphoric acid, hydrofluoric acid, methanesulfonic acid, taurine and sulfamic acid.
The vanadium compound is more than one of vanadium pentoxide, vanadium trioxide and vanadium dioxide; the purity of the vanadium compound is more than or equal to 99.5 percent.
The carbon material in the second step and the third step is more than one of activated carbon, graphene, carbon nano tubes and acetylene black; the carbon material has a particle size of less than 74 μm and accounts for 60-85 wt%.
The binder in the second step and the third step is more than one of polytetrafluoroethylene, polyvinylidene fluoride and polyvinyl alcohol.
The organic solvent in the second step and the third step is one of ethanol, acetone, dimethylacetamide and dimethylformamide.
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