Aqueous iron ion secondary battery assembled in atmospheric environment and preparation method thereof
By controlling the pH value and increasing the coordination competition of proton/O2 in the electrolyte of the aqueous iron ion secondary battery, the problem of Fe2+ in the electrolyte is solved, and the possibility of assembling the battery in the atmospheric environment is realized, the production cost is reduced and the cycle life and discharge specific capacity of the battery are improved.
Patent Information
- Application Number
- CN202510160597.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-13
- Publication Date
- 2025-05-16
AI Technical Summary
The existing water-based iron-ion secondary batteries are easily oxidized because Fe2+ in the electrolyte, which makes it difficult to assemble in the atmospheric environment, increasing production costs and complexity.
By adding acidic aqueous solution and Fe2+ salt to deionized water, an acidic Fe2+ electrolyte with a pH of 1 to 4 was prepared, and assembled into a battery with iron foam and VOPO4·2H2O in an atmospheric environment. This method reduces the dissolved oxygen content in the electrolyte through the coordination competition effect of proton/O2 and inhibits the oxidation of Fe2+.
It realizes the direct assembly of water-based iron ion secondary batteries in an atmospheric environment, reducing production costs and process complexity, and the battery has a cycle life of more than 5,000 hours and a high discharge specific capacity.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention relates to a battery and a manufacturing method thereof, in particular to an aqueous iron ion secondary battery assembled in an atmospheric environment and a manufacturing method thereof. Background Art
[0002] Renewable new energy sources are increasingly used in life, and the resulting safety and cost issues need to be solved urgently. At present, lithium-ion batteries have occupied a large share of the energy storage market with their advantages of high operating voltage, large capacity, and long cycle life, and have become the first choice for powering large-scale energy storage systems. However, problems such as high cost, low safety, and environmental pollution of organic electrolytes have limited their subsequent development. To this end, researchers have begun to focus on the development of new energy storage devices with high safety, low cost, and no pollution to the environment. Aqueous ion batteries are expected to replace existing commercial batteries and become mainstream energy storage devices with their advantages of low cost, inherent safety, environmental protection, and simple process. Among them, aqueous iron ion secondary batteries constructed with iron as the negative electrode have become one of the strong candidates for the next generation of large-scale energy storage systems due to their high reserves of raw materials, low cost, and high safety of electrolytes. Iron is the second largest element in the world in terms of metal reserves. At the same time, when it is used as an electrochemical raw material, it has an extremely high theoretical specific capacity (960mAh / g or 7550mAh / cm 3 ) and a low hydrogen evolution potential (-0.44V vs. SHE), which makes it have a good advantage when used as a negative electrode in aqueous iron ion secondary batteries. 2+ It is easily oxidized by O2 dissolved in the solution to become Fe2O3 precipitate and lose its original electrochemical properties, so the existing aqueous iron ion secondary battery assembly schemes must be carried out in an oxygen-free environment glove box, which greatly increases its production cost and complexity.
[0003] Fe in electrolyte 2+ It is easy to be oxidized. The root cause is the presence of a large amount of dissolved oxygen in the electrolyte. 2+ The most scientific way to prevent oxidation is to keep the dissolved oxygen content in the electrolyte at an extremely low value for a long time. The electrolyte is an important component of the battery, and it has a significant impact on the battery's cycle life, electrochemical performance, safety, etc. So far, all the reported work in aqueous iron ion secondary batteries has used ferrous salts with a pH of 5 as the electrolyte. This results in the carriers (Fe 2+ ) is easily oxidized, and the problem has not been solved. That is, the assembly of aqueous iron ion secondary batteries directly in the air without the oxygen-free environment of the glove box has not been successful. Therefore, it is urgent but also very challenging to develop a technology that can realize the assembly of aqueous iron ion secondary batteries in the air. Summary of the invention
[0004] Purpose of the invention: In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing an aqueous iron ion secondary battery that is assembled in an atmospheric environment with extremely low dissolved oxygen content and is separated from an anaerobic environment, reduces production costs and process complexity.
[0005] Technical solution: The method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment of the present invention comprises the following steps:
[0006] Step 1: Add an acidic aqueous solution to deionized water to acidify the solution, and add Fe 2+ Salt as solute;
[0007] Step 2: Use an acidic aqueous solution to slightly adjust the acidity of the solution obtained in step 1 to obtain an acidic Fe 2+ Electrolyte;
[0008] Step 3: Assemble the product obtained in step 2, foamed iron and VOPO4·2H2O into an aqueous iron ion secondary battery under atmospheric conditions.
[0009] During the preparation of aqueous iron ion secondary battery electrolyte, it was found that protons / O2 react with Fe 2+ There is a coordination competition phenomenon during solvation coordination. At the same time, the dissolved oxygen concentration in the aqueous solution is affected to a certain extent by the concentration of various ions, that is, the increase in the proton concentration in the solution will reduce the dissolved oxygen concentration. Based on this, an aqueous iron ion secondary battery electrolyte with extremely low dissolved oxygen content is prepared, so that the aqueous iron ion secondary battery can be directly assembled in the atmospheric environment.
[0010] Furthermore, in step 1, the acidic aqueous solution is one or more of a hydrochloric acid aqueous solution, a sulfuric acid aqueous solution, a trifluoromethanesulfonic acid aqueous solution, a nitric acid aqueous solution, an acetic acid aqueous solution and a perchloric acid aqueous solution.
[0011] Furthermore, in step 1, the ionic resistance of the deionized water is >10 MΩ, and the total organic carbon content is <50 ppb.
[0012] Furthermore, in step 1, the concentration of the acidic aqueous solution is 0.1 to 1.0 mol / L, Fe 2+ The salt concentration is 0.1~5mol / L.
[0013] Furthermore, in step 1, the pH value of the solution after acidification is 0-6.
[0014] Furthermore, in step 1, Fe 2+ The salt is any one of ferrous chloride, ferrous sulfate, ferrous trifluoromethanesulfonate, ferrous nitrate, ferrous acetate and ferrous perchlorate. 2+The purity of the salt is >98%. Fe 2+ The salt was stirred until the solid was completely dissolved. Then, an acidic aqueous solution with a corresponding pH value was used to dissolve the Fe 2+ Make up to volume with salt solution.
[0015] Furthermore, in step 2, the volume of the acidic aqueous solution does not exceed 10% of the volume of the solution obtained in step 1. 2+ A small amount of acidic aqueous solution of a specified concentration is added to the salt solution, and a pH meter is used to monitor the pH change and perform fine adjustment on the pH of the solution.
[0016] Furthermore, in step three, the foamed iron is the negative electrode and VOPO4·2H2O is the positive electrode.
[0017] The method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment disclosed in the present invention can obtain an aqueous iron ion secondary battery assembled in an atmospheric environment, and the cycle life of the battery exceeds 5000 hours.
[0018] Furthermore, the assembled aqueous iron ion secondary battery has a high discharge specific capacity of 192 mAh / g and a cycle life of more than 1300 times at a current density of 0.1 A / g.
[0019] Preparation principle: To realize the assembly of aqueous iron ion secondary batteries directly in the atmosphere without the oxygen-free glove box, it is necessary to reduce the dissolved oxygen content in the electrolyte and inhibit the Fe 2+ The behavior of being oxidized. In an aqueous solution, the specific value of the dissolved oxygen content is affected by the exchange of O2 in the solution and O2 in the air, and the retention of dissolved oxygen molecules in the aqueous solution mainly depends on the weak hydrogen bonds formed between O2 and H2O. When the concentration of weak hydrogen bonds in the aqueous solution is stable and the gas exchange rate reaches equilibrium, the dissolved oxygen content in the aqueous solution tends to be stable. The balance of the gas exchange rate is affected by the concentration of various ions in the aqueous solution. That is, when the ion concentration in the aqueous solution increases, the concentration of weak hydrogen bonds formed between O2 and H2O will be reduced to a certain extent, thereby breaking the balance of the gas exchange rate and reducing the exchange rate. At the same time, in Fe 2+ In the salt electrolyte, there is Fe 2+ In solution, various molecules and ions interact with Fe 2+ When forming coordination, protons will compete with dissolved O2 for coordination. 2+ When a high concentration of protons is added to the salt electrolyte, it will hinder the dissolution of O2 and Fe to a certain extent. 2+ The formation of coordination can further reduce the dissolved oxygen content in the electrolyte. Based on the above dual characteristics, the prepared Fe 2+Salt electrolyte has an ultra-low dissolved oxygen content, and O2 in the air is difficult to dissolve into the electrolyte. This makes the Fe 2+ The oxidation behavior is suppressed, thereby achieving long-term stability of the electrolyte in the air, allowing aqueous iron ion secondary batteries to be assembled in the air, reducing their production costs and process complexity.
[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant features:
[0021] 1. Prepared Fe 2+ Salt electrolyte can be used to assemble aqueous iron ion secondary batteries directly in the atmospheric environment, no longer relying on the glove box in an oxygen-free environment, which greatly reduces its production cost and process complexity;
[0022] 2. Fe prepared in the present invention 2+ Salt electrolyte can be stored directly in the air, which has the advantage of long-term stable storage;
[0023] 3. Fe 2+ Salt electrolyte can effectively inhibit the Fe 2+ Oxidized;
[0024] 4. Fe prepared by the present invention 2+ The aqueous iron ion secondary battery assembled with salt electrolyte, foamed iron and VOPO4·2H2O has a cycle life of more than 5000 hours. At the same time, the battery has a high discharge specific capacity of 192mAh / g and a cycle life of more than 1300 times at a current density of 0.1A / g. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 This is a photo of the morphology of the foamed iron after being immersed in electrolytes with different pH values for 120 minutes;
[0026] Figure 2 is a photo of the aqueous iron ion secondary battery of the present invention charging a mobile phone;
[0027] Figure 3 is a constant current charge and discharge curve of the aqueous iron ion secondary battery of the present invention;
[0028] Figure 4 1 is a voltage-time cycle diagram of the aqueous iron ion secondary battery of the present invention;
[0029] Figure 5 It is the specific capacity and coulombic efficiency long cycle diagram of the aqueous iron ion secondary battery of the present invention;
[0030] Figure 6It is a photograph showing the changes of the acidic FeSO4-H2SO4 electrolyte of the present invention and the conventional FeSO4 electrolyte when stored in air;
[0031] Figure 7 It is a graph of dissolved oxygen content in aqueous sulfuric acid solutions at different pH values;
[0032] Figure 8 It is a graph of dissolved oxygen content of acidic FeSO4-H2SO4 electrolyte with different pH values;
[0033] Fig. 9 It is the Raman spectrum data diagram of acidic FeSO4-H2SO4 electrolyte with different pH values;
[0034] Fig.10 The acidic FeSO4-H2SO4 electrolyte synthesized in the embodiment of the present invention is Fe 2+ The molecular dynamics simulation calculation model diagram and coordination data diagram centered on the pH = 1 ferrous sulfate electrolyte (a) is the molecular dynamics model of the pH = 1 ferrous sulfate electrolyte, and (b) is the pH = 1 ferrous sulfate electrolyte with Fe 2+ The radial distribution function centered at (c) is the Fe 2+ The coordination number of various particles centered at ;
[0035] Fig.11 The conventional FeSO4 electrolyte synthesized in the comparative example of the present invention is Fe 2+ The molecular dynamics simulation calculation model diagram and coordination data diagram centered on the graph, where (a) is the molecular dynamics model of the traditional ferrous sulfate electrolyte, and (b) is the traditional ferrous sulfate electrolyte with Fe 2+ The radial distribution function centered at (c) is the radial distribution function of the traditional ferrous sulfate electrolyte with Fe 2+ The coordination number of various particles centered at ;
[0036] Fig.12 The Fe 2+ Schematic diagram of the solvation shell as the center, wherein (a) is the acidic FeSO4-H2SO4 electrolyte of Example 1, and (b) is the traditional FeSO4 electrolyte of Comparative Example 3;
[0037] Fig.13 It is a bar chart of different battery production costs. DETAILED DESCRIPTION
[0038] Unless otherwise specified, the materials, reagents, instruments, etc. used in the following examples and comparative examples can be obtained from commercial sources. Experimental methods without specific conditions are usually carried out under conventional conditions or conditions recommended by the manufacturer. The ionic resistance of deionized water is >10MΩ, and the total amount of organic carbon is <50ppb. Fe 2+ The purity of the salt is >98%, and it is directly prepared using a water purifier produced by Moker Chemical Technology (Shanghai) Co., Ltd.
[0039] Example 1
[0040] A method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment comprises the following steps:
[0041] (1) Take 10 mL (concentration 98%, density 1.84 g / cm 3 ) sulfuric acid was added to 90 mL of deionized water, stirred for 60 minutes, and cooled to room temperature to obtain a 100 mL sulfuric acid aqueous solution A with a concentration of 1.0 mol / L.
[0042] (2) 50 mL of deionized water was measured and slowly added with sulfuric acid aqueous solution A. The pH value of the solution was monitored with a JENCO 6173 pH meter. The sulfuric acid aqueous solution B was acidified to obtain a solution pH value of 0.1.
[0043] (3) Measure 10 mL of sulfuric acid aqueous solution B with a pH value of 0.1, place it in a 30 mL culture bottle, weigh 5.56 g of FeSO4, add it, and stir evenly until it is completely dissolved to obtain a FeSO4-H2SO4 mixed solution C with a pH value of 0 to 6.
[0044] (4) Add sulfuric acid aqueous solution B with the same pH value to the mixed solution C obtained in step (3) to make the volume 18-19 mL to obtain a FeSO4-H2SO4 mixed solution D with a concentration of 1 mol / L.
[0045] (5) Slowly add a small amount of sulfuric acid aqueous solution A to solution D, and use a pH meter to monitor the pH change of the solution and make slight adjustments to the solution to obtain an acidic FeSO4-H2SO4 electrolyte with a pH value of 1.
[0046] (6) The foamed iron is used as the negative electrode with a purity of 99.99%, and VOPO4·2H2O (70% VOPO4·2H2O active material, 20% acetylene black conductive agent, and 10% PVDF binder) is used as the positive electrode, which is coated on the surface of the stainless steel foil. The product obtained in step (5) is assembled with the foamed iron and VOPO4·2H2O in an atmospheric environment to form an aqueous iron ion secondary battery (Fe / / Fe 2+ Salt / / VOPO4·2H2O battery).
[0047] Example 2
[0048] A method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment comprises the following steps:
[0049] (1) Take 8 mL (concentration 98%, density 1.84 g / cm 3 ) Sulfuric acid was added to 92 mL of deionized water, stirred for 60 minutes, and cooled to room temperature to obtain a 100 mL aqueous solution of sulfuric acid A with a concentration of 0.1 to 1.0 mol / L.
[0050] (2) 50 mL of deionized water was measured and slowly added with sulfuric acid aqueous solution A. The pH value of the solution was monitored with a JENCO 6173 pH meter. The sulfuric acid aqueous solution B was acidified to obtain a solution pH value of 2.1.
[0051] (3) Measure 10 mL of sulfuric acid aqueous solution B with a pH value of 2.1, place it in a 30 mL culture bottle, weigh 5.56 g of FeSO4, add it, and stir evenly until it is completely dissolved to obtain a FeSO4-H2SO4 mixed solution C with a pH value of about 2.
[0052] (4) Add sulfuric acid aqueous solution B with the same pH value to the mixed solution C obtained in step (3) to make the volume 18-19 mL to obtain a FeSO4-H2SO4 mixed solution D with a concentration of 1 mol / L.
[0053] (5) Slowly add a small amount of sulfuric acid aqueous solution A to solution D, and use a pH meter to monitor the pH change of the solution and make slight adjustments to the solution to obtain an acidic FeSO4-H2SO4 electrolyte with a pH value of 2.
[0054] (6) The foamed iron is used as the negative electrode with a purity of 99.99%, and VOPO4·2H2O (70% VOPO4·2H2O active material, 20% acetylene black conductive agent, and 10% PVDF binder) is used as the positive electrode, which is coated on the surface of the stainless steel foil. The product obtained in step (5) is assembled with the foamed iron and VOPO4·2H2O in an atmospheric environment to form an aqueous iron ion secondary battery (Fe / / Fe 2+ Salt / / VOPO4·2H2O battery).
[0055] Example 3
[0056] A method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment comprises the following steps:
[0057] (1) Take 7 mL (concentration 98%, density 1.84 g / cm 3) Sulfuric acid was added to 93 mL of deionized water, stirred for 60 minutes, and cooled to room temperature to obtain a 100 mL aqueous solution of sulfuric acid A with a concentration of 0.1 to 1.0 mol / L.
[0058] (2) 50 mL of deionized water was measured and slowly added with sulfuric acid aqueous solution A. The pH value of the solution was monitored with a JENCO 6173 pH meter. The sulfuric acid aqueous solution B was acidified to obtain a solution pH value of 3.1.
[0059] (3) Measure 10 mL of sulfuric acid aqueous solution B with a pH value of 3.1, place it in a 30 mL culture bottle, weigh 5.56 g of FeSO4, add it, and stir evenly until it is completely dissolved to obtain a FeSO4-H2SO4 mixed solution C with a pH value of 0 to 6.
[0060] (4) Add sulfuric acid aqueous solution B with the same pH value to the mixed solution C obtained in step (3) to make the volume 18-19 mL to obtain a FeSO4-H2SO4 mixed solution D with a concentration of 1 mol / L.
[0061] (5) Slowly add a small amount of sulfuric acid aqueous solution A to solution D, and use a pH meter to monitor the pH change of the solution and make slight adjustments to the solution to obtain an acidic FeSO4-H2SO4 electrolyte with a pH value of 3.
[0062] (6) The foamed iron is used as the negative electrode with a purity of 99.99%, and VOPO4·2H2O (70% VOPO4·2H2O active material, 20% acetylene black conductive agent, and 10% PVDF binder) is used as the positive electrode, which is coated on the surface of the stainless steel foil. The product obtained in step (5) is assembled with the foamed iron and VOPO4·2H2O in an atmospheric environment to form an aqueous iron ion secondary battery (Fe / / Fe 2+ Salt / / VOPO4·2H2O battery).
[0063] Example 4
[0064] A method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment comprises the following steps:
[0065] (1) Take 6 mL (concentration 98%, density 1.84 g / cm 3 ) Sulfuric acid was added to 94 mL of deionized water, stirred for 60 minutes, and cooled to room temperature to obtain a 100 mL aqueous solution of sulfuric acid A with a concentration of 0.1 to 1.0 mol / L.
[0066] (2) 50 mL of deionized water was measured and slowly added with sulfuric acid aqueous solution A. The pH value of the solution was monitored with a JENCO 6173 pH meter. The pH value of the solution obtained by acidification was 4.2 with sulfuric acid aqueous solution B.
[0067] (3) 10 mL of aqueous sulfuric acid solution B with a pH value of 4.2 was measured and placed in a 30 mL culture bottle, and 5.56 g of FeSO4 was weighed and added thereto. The mixture was stirred evenly until completely dissolved to obtain a FeSO4-H2SO4 mixed solution C with a pH value of 4.2.
[0068] (4) Add sulfuric acid aqueous solution B with the same pH value to the mixed solution C obtained in step (3) to make the volume 18-19 mL to obtain a FeSO4-H2SO4 mixed solution D with a concentration of 1 mol / L.
[0069] (5) Slowly add a small amount of sulfuric acid aqueous solution A to solution D, and use a pH meter to monitor the pH change of the solution and make slight adjustments to the solution to obtain an acidic FeSO4-H2SO4 electrolyte with a pH value of 4.
[0070] (6) The foamed iron is used as the negative electrode with a purity of 99.99%, and VOPO4·2H2O (70% VOPO4·2H2O active material, 20% acetylene black conductive agent, and 10% PVDF binder) is used as the positive electrode, which is coated on the surface of the stainless steel foil. The product obtained in step (5) is assembled with the foamed iron and VOPO4·2H2O in an atmospheric environment to form an aqueous iron ion secondary battery (Fe / / Fe 2+ Salt / / VOPO4·2H2O battery).
[0071] Example 5
[0072] A method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment comprises the following steps:
[0073] (1) Take 9 mL of hydrochloric acid (concentration 37%, density 1.18 g / cm 3 , HCl) was added into 91 mL of deionized water, stirred for 60 minutes, and cooled to room temperature to obtain a hydrochloric acid aqueous solution A with a volume of 100 mL and a concentration of 1 mol / L.
[0074] (2) 50 mL of deionized water was measured and slowly added with hydrochloric acid aqueous solution A. The pH value of the solution was monitored with a JENCO 6173 pH meter. The hydrochloric acid aqueous solution B was acidified to obtain a solution with a pH value of 0 to 6.
[0075] (3) Measure 10 mL of hydrochloric acid aqueous solution B with a pH value of 0 to 6, place it in a 30 mL culture bottle, weigh 5.56 g of FeCl2, add it, and stir evenly until it is completely dissolved to obtain a FeCl2-HCl mixed solution C with a pH value of 0 to 6.
[0076] (4) Add hydrochloric acid aqueous solution B with the same pH value to the mixed solution C obtained in step (3) to make the volume 19 mL, and obtain a FeCl2-HCl mixed solution D with a concentration of 1 mol / L.
[0077] (5) Slowly add a small amount of hydrochloric acid aqueous solution A to solution D, and use a pH meter to monitor the pH change of the solution and make slight adjustments to the solution to obtain an acidic FeCl2-HCl electrolyte with a pH value of 1.
[0078] (6) The foamed iron is used as the negative electrode with a purity of 99.99%, and VOPO4·2H2O (70% VOPO4·2H2O active material, 20% acetylene black conductive agent, and 10% PVDF binder) is used as the positive electrode, which is coated on the surface of the stainless steel foil. The product obtained in step (5) is assembled with the foamed iron and VOPO4·2H2O in an atmospheric environment to form an aqueous iron ion secondary battery (Fe / / Fe 2+ Salt / / VOPO4·2H2O battery).
[0079] Example 6
[0080] A method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment comprises the following steps:
[0081] (1) Take 9 mL of trifluoromethanesulfonic acid (concentration 99%, density 1.69 g / cm 3 , HCF3SO3, TfOH) were added into 91 mL of deionized water, stirred for 60 minutes, and cooled to room temperature to obtain a 100 mL trifluoromethanesulfonic acid aqueous solution A with a concentration of 1.0 mol / L.
[0082] (2) 50 mL of deionized water was measured and slowly added with trifluoromethanesulfonic acid aqueous solution A. The pH value of the solution was monitored with a JENCO 6173 pH meter. The trifluoromethanesulfonic acid aqueous solution B was acidified to obtain a solution with a pH value of 0 to 6.
[0083] (3) Measure 10 mL of trifluoromethanesulfonic acid aqueous solution B with a pH value of 0 to 6, place it in a 30 mL culture bottle, weigh 5.56 g of Fe(CF3SO3)2, add it, and stir evenly until it is completely dissolved to obtain a Fe(CF3SO3)2-TfOH mixed solution C with a pH value of 0 to 6.
[0084] (4) Add trifluoromethanesulfonic acid aqueous solution B with the same pH value to the mixed solution C obtained in step (3) to make the volume 19 mL, and obtain a Fe(CF3SO3)2-TfOH mixed solution D with a concentration of 1 mol / L.
[0085] (5) Slowly add a small amount of trifluoromethanesulfonic acid aqueous solution A to solution D, and use a pH meter to monitor the pH change of the solution and make slight adjustments to the solution to obtain an acidic Fe(CF3SO3)2-TfOH electrolyte with a pH value of 1.
[0086] (6) The foamed iron is used as the negative electrode with a purity of 99.99%, and VOPO4·2H2O (70% VOPO4·2H2O active material, 20% acetylene black conductive agent, and 10% PVDF binder) is used as the positive electrode, which is coated on the surface of the stainless steel foil. The product obtained in step (5) is assembled with the foamed iron and VOPO4·2H2O in an atmospheric environment to form an aqueous iron ion secondary battery (Fe / / Fe 2+ Salt / / VOPO4·2H2O battery).
[0087] Example 7
[0088] A method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment comprises the following steps:
[0089] (1) Take 9 mL of nitric acid (concentration 98%, density 1.41 g / cm 3 , HNO3) was added into 91 mL of deionized water, stirred for 60 minutes, and cooled to room temperature to obtain a nitric acid aqueous solution A with a volume of 100 mL and a concentration of 1 mol / L.
[0090] (2) 50 mL of deionized water was measured and slowly added with aqueous nitric acid solution A. The pH value of the solution was monitored with a JENCO 6173 pH meter. The aqueous nitric acid solution B was acidified to obtain a solution with a pH value of 0 to 6.
[0091] (3) Measure 10 mL of nitric acid aqueous solution B with a pH value of 0 to 6, place it in a 30 mL culture bottle, weigh 5.56 g of Fe(NO3)2, add it, and stir evenly until it is completely dissolved to obtain a Fe(NO3)2-HNO3 mixed solution C with a pH value of 0 to 6.
[0092] (4) Add nitric acid aqueous solution B with the same pH value to the mixed solution C obtained in step (3) to make the volume 19 mL, and obtain a Fe(NO3)2-HNO3 mixed solution D with a concentration of 1 mol / L.
[0093] (5) Slowly add a small amount of nitric acid aqueous solution A to solution D, and use a pH meter to monitor the pH change of the solution and make slight adjustments to the solution to obtain an acidic Fe(NO3)2-HNO3 electrolyte with a pH value of 1.
[0094] (6) The foamed iron is used as the negative electrode with a purity of 99.99%, and VOPO4·2H2O (70% VOPO4·2H2O active material, 20% acetylene black conductive agent, and 10% PVDF binder) is used as the positive electrode, which is coated on the surface of the stainless steel foil. The product obtained in step (5) is assembled with the foamed iron and VOPO4·2H2O in an atmospheric environment to form an aqueous iron ion secondary battery (Fe / / Fe 2+ Salt / / VOPO4·2H2O battery).
[0095] Example 8
[0096] A method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment comprises the following steps:
[0097] (1) Take 10 mL of acetic acid (concentration 99.7%, density 1.05 g / cm 3 , CH3COOH) was added into 90 mL of deionized water, stirred for 60 minutes, and cooled to room temperature to obtain 100 mL of acetic acid aqueous solution A with a concentration of 1 mol / L.
[0098] (2) 50 mL of deionized water was measured and slowly added with acetic acid aqueous solution A. The pH value of the solution was monitored with a JENCO 6173 pH meter. The acetic acid aqueous solution B was acidified to obtain a solution with a pH value of 0 to 6.
[0099] (3) Measure 10 mL of acetic acid aqueous solution B with a pH value of 0 to 6, place it in a 30 mL culture bottle, weigh 5.56 g of Fe(CH3COO)2, add it, and stir evenly until it is completely dissolved to obtain a Fe(CH3COO)2-CH3COOH mixed solution C with a pH value of 0 to 6.
[0100] (4) Add acetic acid aqueous solution B with the same pH value to the mixed solution C obtained in step (3) to make the volume 19 mL, and obtain a Fe(CH3COO)2-CH3COOH mixed solution D with a concentration of 2 mol / L.
[0101] (5) Slowly add a small amount of acetic acid aqueous solution A to solution D, and use a pH meter to monitor the pH change of the solution and make slight adjustments to the solution to obtain an acidic Fe(CH3COO)2-CH3COOH electrolyte with a pH value of 1.
[0102] (6) The foamed iron is used as the negative electrode with a purity of 99.99%, and VOPO4·2H2O (70% VOPO4·2H2O active material, 20% acetylene black conductive agent, and 10% PVDF binder) is used as the positive electrode, which is coated on the surface of the stainless steel foil. The product obtained in step (5) is assembled with the foamed iron and VOPO4·2H2O in an atmospheric environment to form an aqueous iron ion secondary battery (Fe / / Fe 2+Salt / / VOPO4·2H2O battery).
[0103] Example 9
[0104] A method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment comprises the following steps:
[0105] (1) Take 9 mL of perchloric acid (concentration 60%, density 1.67 g / cm 3 , HClO4) was added into 91 mL of deionized water, stirred for 60 minutes, and cooled to room temperature to obtain a 100 mL perchloric acid aqueous solution A with a concentration of 1 mol / L.
[0106] (2) 50 mL of deionized water was measured and slowly added with the perchloric acid aqueous solution A. The pH value of the solution was monitored with a JENCO 6173 pH meter. The pH value of the solution obtained by acidification was the perchloric acid aqueous solution B of 0 to 6.
[0107] (3) Measure 10 mL of a perchloric acid aqueous solution B with a pH value of 0 to 6, place it in a 30 mL culture bottle, weigh 5.56 g of Fe(ClO4)2 and add it, stir evenly until it is completely dissolved, to obtain a Fe(ClO4)2-HClO4 mixed solution C with a pH value of 0 to 6.
[0108] (4) Add perchloric acid aqueous solution B with the same pH value to the mixed solution C obtained in step (3) to make the volume 18.5 mL to obtain a Fe(ClO4)2-HClO4 mixed solution D with a concentration of 1 mol / L.
[0109] (5) Slowly add a small amount of perchloric acid aqueous solution A to solution D, and use a pH meter to monitor the pH change of the solution and make slight adjustments to the solution to obtain an acidic Fe(ClO4)2-HClO4 electrolyte with a pH value of 1.
[0110] (6) The foamed iron is used as the negative electrode with a purity of 99.99%, and VOPO4·2H2O (70% VOPO4·2H2O active material, 20% acetylene black conductive agent, and 10% PVDF binder) is used as the positive electrode, which is coated on the surface of the stainless steel foil. The product obtained in step (5) is assembled with the foamed iron and VOPO4·2H2O in an atmospheric environment to form an aqueous iron ion secondary battery (Fe / / Fe 2+ Salt / / VOPO4·2H2O battery).
[0111] Comparative Example 1
[0112] A method for preparing an acidic FeSO4-H2SO4 electrolyte comprises the following steps:
[0113] (1) Take 1-10 mL (concentration 98%, density 1.84 g / cm 3 ) Sulfuric acid is added to 90-99 mL of deionized water, stirred for 60 minutes, and cooled to room temperature to obtain a 100 mL aqueous solution of sulfuric acid A with a concentration of 0.1-1.0 mol / L.
[0114] (2) 50 mL of deionized water was measured and slowly added with sulfuric acid aqueous solution A. The pH value of the solution was monitored with a JENCO 6173 pH meter. The sulfuric acid aqueous solution B was acidified to obtain a solution pH value of 0.1.
[0115] (3) Measure 10 mL of sulfuric acid aqueous solution B with a pH value of 0 to 6, place it in a 30 mL culture bottle, weigh 5.56 g of FeSO4, add it, and stir evenly until it is completely dissolved to obtain a FeSO4-H2SO4 mixed solution C with a pH value of 0 to 6.
[0116] (4) Add sulfuric acid aqueous solution B with the same pH value to the mixed solution C obtained in step (3) to make the volume 18-19 mL to obtain a FeSO4-H2SO4 mixed solution D with a concentration of 1 mol / L.
[0117] (5) Slowly add a small amount of sulfuric acid aqueous solution A to solution D, and use a pH meter to monitor the pH change of the solution and make slight adjustments to the solution to obtain an acidic FeSO4-H2SO4 electrolyte with a pH value of 0.
[0118] Comparative Example 2
[0119] A method for preparing an acidic FeSO4-H2SO4 electrolyte comprises the following steps:
[0120] (1) Take 1-10 mL (concentration 98%, density 1.84 g / cm 3 ) Sulfuric acid is added to 90-99 mL of deionized water, stirred for 60 minutes, and cooled to room temperature to obtain a 100 mL aqueous solution of sulfuric acid A with a concentration of 0.1-1.0 mol / L.
[0121] (2) 50 mL of deionized water was measured and slowly added with sulfuric acid aqueous solution A. The pH value of the solution was monitored with a JENCO 6173 pH meter. The sulfuric acid aqueous solution B was acidified to obtain a solution with a pH value of 0 to 6.
[0122] (3) Measure 10 mL of sulfuric acid aqueous solution B with a pH value of 0 to 6, place it in a 30 mL culture bottle, weigh 5.56 g of FeSO4, add it, and stir evenly until it is completely dissolved to obtain a FeSO4-H2SO4 mixed solution C with a pH value of 0 to 6.
[0123] (4) Add sulfuric acid aqueous solution B with the same pH value to the mixed solution C obtained in step (3) to make the volume 18-19 mL, and obtain a FeSO4-H2SO4 mixed solution D with a concentration of 0.1-5 mol / L.
[0124] (5) Slowly add a small amount of sulfuric acid aqueous solution A to solution D, and use a pH meter to monitor the pH change of the solution and make slight adjustments to the solution to obtain an acidic FeSO4-H2SO4 electrolyte with a pH value of 0.5.
[0125] The foamed iron was soaked in the acidic FeSO4-H2SO4 electrolyte of Examples 1 to 4 and Comparative Examples 1 to 2 for 120 minutes. Figure 1 As shown in the figure, when the pH of the electrolyte is less than 1, the corrosion effect is very obvious. Therefore, the Fe 2+ The pH of the salt electrolyte is 1-4, and there is no corrosion to the foamed iron.
[0126] like Figure 2 As shown, the aqueous iron ion secondary battery obtained in Example 1 was tested for battery specific capacity and cycle performance by constant current charge and discharge method. Figure 3 , the aqueous iron ion secondary battery has a specific capacity of 192 mAh / g at a current density of 0.1 A / g. Figure 4-5 The aqueous iron-ion secondary battery has a cycle life of more than 5,000 hours and more than 1,300 cycles.
[0127] Comparative Example 3
[0128] This comparative example is for preparing a traditional FeSO4 electrolyte, and its preparation steps are the same as those in Example 1, with the only difference being that when preparing the sulfuric acid aqueous solution B by acidification in step (2), the pH value is adjusted to 5.5; and then step (5) is fine-tuned to obtain a FeSO4 aqueous solution with a pH of 5 and a 1 mol / L value.
[0129] The acidic FeSO4-H2SO4 electrolyte with a pH value of 1 in Example 1 and the conventional FeSO4 electrolyte with a pH value of 5 in Comparative Example 3 were placed in the air. Figure 6 As shown in the figure, Fe quickly appeared in the traditional FeSO4 electrolyte with pH = 5. 2+ The precipitate is generated after oxidation, while the FeSO4-H2SO4 electrolyte with pH = 1 can remain clear and transparent for a long time, indicating that the FeSO4-H2SO4 electrolyte with pH = 1 has better stability in the air.
[0130] Comparative Example 4
[0131] The pH value of deionized water was directly adjusted to 0.5, 1, 2, 3, 4, and 5 using the sulfuric acid aqueous solution A in Example 1, and monitored using a JENCO6173 pH meter. The dissolved oxygen content of the sulfuric acid aqueous solution with different pH values, the electrolyte in the example, and the electrolyte in Comparative Example 3 was tested using an AZ8413 dissolved oxygen meter. The results are as follows: Figures 7-8 As shown in the figure, as the proton concentration in the solution increases, the dissolved oxygen content decreases significantly.
[0132] like Fig. 9 As shown in the Raman data of the sulfuric acid aqueous solution with pH = 1 and 5 and the electrolyte with pH = 1 and 5, it is found that the peaks at 2800-3000 cm -1 The characteristic peak of the wavelength changes significantly. This peak is the characteristic peak of the weak hydrogen bond formed between H2O and dissolved O2 molecules in the solution, indicating that at pH = 1, Fe 2+ The salt electrolyte has an extremely low content of weak hydrogen bonds, which corresponds to the extremely low dissolved oxygen content obtained in its testing.
[0133] Molecular dynamics simulation was used to construct a FeSO4-H2SO4 electrolyte system model with pH = 1 and a traditional FeSO4 electrolyte system model to obtain the Fe 2+ The radial distribution function and coordination number information centered on Figures 10-11 As shown in the figure, when the electrolyte contains a large number of protons, the protons and dissolved O2 molecules react with Fe 2+ There is an obvious competition phenomenon when forming the solvation structure coordination, which can greatly reduce the dissolved oxygen concentration in the electrolyte, which can explain Figure 8 The phenomenon of extremely low oxygen concentration in FeSO4-H2SO4 electrolyte with pH = 1 is shown in the specific solvation shell structure model. Fig.12 At the same time, the cost of the aqueous iron ion secondary battery assembled using the acidic FeSO4-H2SO4 electrolyte prepared by the present invention is the lowest compared to the current mainstream ion battery. Fig.13 Wherein, AIB: aluminum ion battery, LIB: lithium ion battery, ZIB: zinc ion battery, LA: lead-acid battery, FIB: aqueous iron ion secondary battery of the present invention.
Claims
1. A method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment, characterized in that: The following steps are involved: Step 1: Add an acidic aqueous solution to deionized water to acidify the solution, and add Fe 2+ Salt as solute; Step 2: Use an acidic aqueous solution to slightly adjust the acidity of the solution obtained in step 1 to obtain an acidic Fe 2+ Electrolyte; Step 3: Assemble the product obtained in step 2, foamed iron and VOPO4·2H2O into an aqueous iron ion secondary battery under atmospheric conditions.
2. The method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment according to claim 1, characterized in that: In the step 1, the acidic aqueous solution is one or more of a hydrochloric acid aqueous solution, a sulfuric acid aqueous solution, a trifluoromethanesulfonic acid aqueous solution, a nitric acid aqueous solution, an acetic acid aqueous solution and a perchloric acid aqueous solution.
3. The method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment according to claim 1, characterized in that: In the step 1, the ionic resistance of the deionized water is greater than 10 MΩ, and the total amount of organic carbon is less than 50 ppb.
4. The method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment according to claim 1, characterized in that: In step 1, the concentration of the acidic aqueous solution is 0.1-1.0 mol / L, Fe 2+ The salt concentration is 0.1~5mol / L.
5. The method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment according to claim 1, characterized in that: In the step 1, the pH value of the solution after acidification is 0-6.
6. The method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment according to claim 1, characterized in that: In the step 1, Fe 2+ The salt is any one of ferrous chloride, ferrous sulfate, ferrous trifluoromethanesulfonate, ferrous nitrate, ferrous acetate and ferrous perchlorate.
7. The method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment according to claim 1, characterized in that: In the step 1, Fe 2+ The purity of the salt was >98%.
8. The method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment according to claim 1, characterized in that: In the step 2, the volume of the acidic aqueous solution does not exceed 10% of the volume of the solution obtained in the step 1.
9. The method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment according to claim 1, characterized in that: In the step 3, the foamed iron is the negative electrode and the VOPO4·2H2O is the positive electrode.
10. The aqueous iron ion secondary battery assembled in an atmospheric environment obtained by the method for preparing an aqueous iron ion secondary battery assembled in an atmospheric environment according to any one of claims 1 to 9 is characterized in that: Its cycle life exceeds 5000 hours.