Method and device for preparing aqueous proton battery electrolyte based on magnesium method flue gas desulfurization byproduct and aqueous proton battery

Abstract

The invention discloses a method and a device for preparing an aqueous proton battery electrolyte based on a magnesium method flue gas desulfurization byproduct and an aqueous proton battery. The method comprises the following steps: carrying out oxidation treatment and impurity removal treatment on the magnesium-method flue gas desulfurization byproduct to obtain a high-purity magnesium sulfate solution; and mixing the high-purity magnesium sulfate solution and the sulfuric acid solution to obtain the aqueous proton battery electrolyte. According to the method, the magnesium-method flue gas desulfurization by-products are directly used for preparing the aqueous proton battery electrolyte after being oxidized and subjected to impurity removal, so that the problems of accumulation and treatment of the magnesium-method flue gas desulfurization by-products are solved, the solid waste treatment cost is reduced, and resource recycling is realized; the preparation process disclosed by the invention is low in energy consumption, greatly reduces the production cost of the electrolyte, and is environment-friendly. Compared with the traditional pure sulfuric acid electrolyte, the electrolyte prepared by the invention can obviously improve the cycle performance of the water-based proton battery, greatly enhance the rate capability, meet the high-power requirement, and realize double breakthrough of high-value utilization of solid wastes and high-performance water-based proton batteries.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resource utilization of magnesium flue gas desulfurization by-products, and particularly relates to a method and device for preparing an aqueous proton battery electrolyte based on magnesium flue gas desulfurization by-products and an aqueous proton battery. BACKGROUND

[0002] The magnesium flue gas desulfurization technology is widely used in the coal-fired power plant, steel plant, cement plant and other industries due to its high desulfurization efficiency, difficulty in fouling and low cost. However, the technology produces about 20 million tons of magnesium-containing by-products, i.e. mixed slurry containing magnesium sulfite and magnesium sulfate, every year, and the mass ratio of magnesium sulfate to magnesium sulfite is 78% to 85%.

[0003] The magnesium sulfite oxidation method is a traditional way of recycling magnesium flue gas desulfurization by-products, and has the advantages of low cost and low energy consumption. However, the application field of the prepared product is limited, mainly in the construction and agriculture, and the product has low added value, which cannot realize large-scale production. For example, in the field of building materials, the basic magnesium sulfate whiskers prepared by the dynamic crystallization process have low market price due to poor compressive strength. In the field of agriculture, the magnesium sulfate heptahydrate fertilizer obtained by oxidizing magnesium sulfite is impacted by the price competition in the international market, and the product has poor slow-release effect and low profit. In view of the above difficulties in the two main application fields, the magnesium sulfite oxidation product cannot obtain good economic benefits, and is currently treated as solid waste for landfill, which increases the environmental treatment cost by 12 to 15 yuan per ton of desulfurization product.

[0004] Therefore, it is urgent to explore a high-value-added application way of magnesium flue gas desulfurization by-products. SUMMARY

[0005] The present application aims to overcome the above technical deficiencies, and provides a method and device for preparing an aqueous proton battery electrolyte based on magnesium flue gas desulfurization by-products and an aqueous proton battery, which solves the technical problem of low added value utilization rate of magnesium flue gas desulfurization by-products in the prior art.

[0006] In a first aspect, the present application provides a method for preparing an aqueous proton battery electrolyte based on magnesium flue gas desulfurization by-products, which comprises the following steps: oxidizing and impurity-removing the magnesium flue gas desulfurization by-products to obtain a high-purity magnesium sulfate solution; mixing the high-purity magnesium sulfate solution and a sulfuric acid solution to obtain the aqueous proton battery electrolyte; wherein the magnesium flue gas desulfurization by-products comprise magnesium sulfate and magnesium sulfite.

[0007] In a second aspect, the present application provides a device for preparing an aqueous proton battery electrolyte based on a magnesium method flue gas desulfurization by-product, comprising an oxidation unit, a impurity removal unit and an electrolyte preparation unit; the discharge end of the oxidation unit is in communication with the feed end of the impurity removal unit, and the discharge end of the impurity removal unit is in communication with the feed end of the electrolyte preparation unit. The device for preparing an aqueous proton battery electrolyte based on a magnesium method flue gas desulfurization by-product is used to perform the method for preparing an aqueous proton battery electrolyte based on a magnesium method flue gas desulfurization by-product provided in the first aspect of the present application.

[0008] In a third aspect, the present application provides an aqueous proton battery, which comprises the aqueous proton battery electrolyte provided in the first aspect of the present application and a negative electrode sheet; wherein the negative electrode sheet comprises a molybdenum trioxide negative electrode active material.

[0009] Compared with the prior art, the present application has the following beneficial effects: The present application directly uses the magnesium method flue gas desulfurization by-product after oxidation and impurity removal for preparing an aqueous proton battery electrolyte, solves the problems of accumulation and treatment of the magnesium method flue gas desulfurization by-product, reduces the solid waste disposal cost, realizes resource recycling, and has low energy consumption in the preparation process, greatly reduces the electrolyte production cost, and is environmentally friendly. In addition, compared with the traditional pure sulfuric acid electrolyte, the electrolyte prepared by the present application can significantly improve the cycle performance of the aqueous proton battery (by inhibiting the corrosion of free water to prolong the service life of the battery), and greatly enhance the rate performance (by improving the conductivity to realize fast charging and discharging), meet the high power demand, realize the high value utilization of solid waste, and achieve the dual breakthrough of high performance aqueous proton battery. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a structural schematic diagram of an embodiment of the device for preparing an aqueous proton battery electrolyte based on a magnesium method flue gas desulfurization by-product provided by the present application; wherein 1 is an oxidation unit, 2 is a impurity removal unit, and 3 is an electrolyte preparation unit; Figure 2 is an X-ray diffraction pattern of molybdenum trioxide provided by the present application; Figure 3 is a microstructure diagram of molybdenum trioxide provided by the present application; wherein (a) is an optical microscope diagram, and (b) and (c) are scanning electron microscope diagrams; Figure 4 is a CV curve of the electrolyte based on Example 1 of the present application at a scanning speed of 1, 2, 5 and 10 mV / s; Figure 5 is a CV curve of the electrolyte based on Comparative Example 1 of the present application at a scanning speed of 1, 2, 5 and 10 mV / s; Figure 6 is a rate curve of the electrolyte based on Example 1 and Comparative Example 1 of the present application; Figure 7 These are charge-discharge cycle curves of different electrolytes based on Examples 1-2 of the present invention and Comparative Examples 1-2. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0012] During the magnesium-based flue gas desulfurization process, a large amount of magnesium-containing by-products will be produced, and magnesium sulfate solution can be obtained after oxidation and impurity removal. If the solution is crystallized and then sold on the market, it will not only consume a lot of energy, but also reduce product revenue, which makes the high-value utilization of desulfurization by-products face challenges. At the same time, in the field of aqueous proton battery research, MoO3 has been widely studied because of its high specific capacity. However, the current proton battery electrolyte is mainly sulfuric acid aqueous solution. However, during the charge and discharge process, sulfuric acid electrolyte has strong corrosiveness to the electrodes and is prone to side reactions such as hydrogen evolution and oxygen evolution, resulting in poor rate performance of the assembled battery and poor charge and discharge cycle stability, making it difficult to meet the needs of high-power and long-life energy storage scenarios. At present, there is no report on the use of magnesium-based flue gas desulfurization by-products as additives in aqueous proton battery electrolytes after treatment. Based on this, the present invention is proposed.

[0013] In a first aspect, the present invention provides a method for preparing an aqueous proton battery electrolyte based on a byproduct of a magnesium-based flue gas desulfurization process, comprising the following steps: S1. Oxidizing and removing impurities from the by-products of magnesium-based flue gas desulfurization to obtain a high-purity magnesium sulfate solution; S2. Mixing high-purity magnesium sulfate solution and sulfuric acid solution to obtain aqueous proton battery electrolyte; wherein, the main components of the by-products of magnesium-based flue gas desulfurization are magnesium sulfate and magnesium sulfite, and contain a small amount of impurity ions such as calcium ions and iron ions.

[0014] The present invention uses the reaction principles of redox and chemical precipitation to convert the reducing magnesium sulfite in the by-product of magnesium-based flue gas desulfurization into stable magnesium sulfate through forced oxidation, thereby preventing side reactions in the electrolyte from affecting battery performance. Subsequently, impurity ions are further effectively removed to obtain a high-purity magnesium sulfate solution, which is directly used as an additive to the electrolyte of an aqueous proton battery to improve the cycle performance and rate performance of the aqueous proton battery.

[0015] In this embodiment, step S1 includes: S11, mixing the magnesium flue gas desulfurization byproduct and water, and adjusting the pH to 4.5-5.5 to obtain a mixed slurry; S12, air is introduced into the mixed slurry to perform an oxidation reaction to obtain an oxidized slurry; S13, the oxidized slurry is mixed with magnesium carbonate to perform a first precipitation reaction, and then magnesium hydroxide is added to perform a second precipitation reaction, and a high-purity magnesium sulfate solution is obtained through solid-liquid separation. In this step, the filter residue (mainly composed of CaCO3 and Fe(OH)3) obtained after the solid-liquid separation can be sold after treatment to be used for preparing water purifying agents, pigments, catalysts and other products.

[0016] In the present application, the mixed slurry with a pH of 4.5-5.5 is oxidized by air, which is conducive to the complete oxidation of magnesium sulfite into magnesium sulfate solution without using oxidizing reagents; at the same time, based on the difference in solubility product, calcium ions are converted into calcium carbonate precipitate by using magnesium carbonate, and iron ions are formed into iron hydroxide precipitate by using magnesium hydroxide to adjust the pH value, thereby effectively removing impurity ions and obtaining a high-purity magnesium sulfate solution. If the pH is too low, the concentration of SO3 2- in the solution and the solubility of oxygen will be reduced, which is not conducive to the oxidation of MgSO3; if the pH is too high, the solubility of MgSO3 will be reduced, and the dissolution and diffusion of oxygen will be hindered, which is also not conducive to the oxidation of MgSO3.

[0017] In the present embodiment, the liquid-solid mass ratio during the mixing of the magnesium method flue gas desulfurization by-product and water is (2-4):1, including but not limited to 2:1, 2.5:1, 3:1, 3.5:1, 4:1, etc. By controlling the liquid-solid mass ratio within the above range, the present application can improve the concentration of the high-purity magnesium sulfate solution while ensuring the oxidation and impurity removal effect, thereby avoiding the problem that the low concentration of magnesium sulfate is not sufficient to improve the performance of the aqueous proton battery when directly used for preparing the electrolyte of the aqueous battery, or the problem that a large amount of magnesium carbonate and / or magnesium sulfate needs to be added, resulting in increased cost.

[0018] In the present embodiment, the pH is adjusted to 4.5-5.5 by using sulfuric acid with a mass fraction of 90%-98%, including but not limited to 4.5, 4.8, 5, 5.2, 5.5, etc.

[0019] In the present embodiment, the air flow is 0.1-3 L / min, including but not limited to 0.1 L / min, 0.5 L / min, 1 L / min, 2 L / min, 3 L / min, etc., the oxidation temperature is 35-55°C, including but not limited to 35°C, 40°C, 45°C, 50°C, 55°C, etc., and the oxidation time is 10-180 min, including but not limited to 10 min, 50 min, 100 min, 150 min, 180 min, etc. By setting the air flow, oxidation temperature and oxidation time within the above ranges, magnesium sulfite can be completely oxidized into magnesium sulfate.

[0020] In the embodiment, the molar ratio of carbonate ions to calcium ions is controlled by adding magnesium carbonate to be (1.1-1.5):1, including but not limited to 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, etc. If the amount of magnesium carbonate added is too low, the calcium ion precipitation will not be complete; if the amount of magnesium carbonate added is too high, it will cause waste.

[0021] In the embodiment, the temperature of the first precipitation reaction is room temperature (generally 20-30°C), and the time of the first precipitation reaction is 5-10 min. By controlling the temperature of the first precipitation reaction and the time of the first precipitation reaction within the above range, the calcium ions can be completely converted into calcium carbonate precipitate.

[0022] In the embodiment, the pH value is controlled to be ≥5.0 (preferably 5.0-7.0) by adding magnesium hydroxide for the second precipitation reaction. After oxidation of magnesium sulfite, the pH value of the system will decrease slightly, and by controlling the pH value within the above range by adding magnesium hydroxide, the iron ions can form iron hydroxide precipitate, effectively removing the iron ions.

[0023] In the embodiment, the temperature of the second precipitation reaction is room temperature (generally 20-30°C), and the time of the second precipitation reaction is 5-10 min. By controlling the temperature of the second precipitation reaction and the time of the second precipitation reaction within the above range, the iron ions can be completely precipitated.

[0024] In the embodiment, the concentration of magnesium sulfate in the high-purity magnesium sulfate solution is 1-3 mol / L, including but not limited to 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, etc. If the concentration of magnesium sulfate in the high-purity magnesium sulfate solution is too high, the viscosity of the early oxidation reaction system will be too large, and the oxidation rate will decrease significantly; if the concentration of magnesium sulfate in the high-purity magnesium sulfate solution is too low, it will lead to insufficient performance improvement of the aqueous proton battery when directly used to prepare the aqueous battery electrolyte, or a large amount of magnesium carbonate and / or magnesium sulfate needs to be added, resulting in increased cost.

[0025] In the embodiment, water, magnesium sulfate and magnesium carbonate can also be selectively added in step S2 according to actual needs until the aqueous proton battery electrolyte meets the concentration requirements.

[0026] In the embodiment, the concentration of sulfuric acid in the aqueous proton battery electrolyte is 1-3 mol / L, including but not limited to 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, etc., and the concentration of magnesium sulfate is 1-3 mol / L, including but not limited to 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, etc. If the concentration of sulfuric acid is too low, the proton concentration will be too low, which will lead to a decrease in the cycle stability of the battery; if the concentration of sulfuric acid is too high, it will lead to serious corrosion of the electrode and the current collector, which will easily damage the system; if the concentration of magnesium sulfate is too low, it will lead to insufficient improvement in the rate performance and cycle performance of the battery; if the concentration of magnesium sulfate is too high, it will lead to an increase in the viscosity of the electrolyte, a decrease in the ion conduction rate, a decrease in the capacity of the battery, and an increase in the production cost.

[0027] Referring to Figure 1 In a second aspect, the application provides a device for preparing an aqueous proton battery electrolyte based on a magnesium method flue gas desulfurization by-product, comprising an oxidation unit 1, a impurity removal unit 2, and an electrolyte preparation unit 3; the discharge end of the oxidation unit 1 is in communication with the feed end of the impurity removal unit 2, and the discharge end of the impurity removal unit 2 is in communication with the feed end of the electrolyte preparation unit 3. The device for preparing an aqueous proton battery electrolyte based on a magnesium method flue gas desulfurization by-product is used to perform the method for preparing an aqueous proton battery electrolyte based on a magnesium method flue gas desulfurization by-product provided in the first aspect of the application.

[0028] In the embodiment, the oxidation unit 1 comprises an oxidation tank and a fan, and the oxidation tank and the fan are in communication through a conveying pipeline. Through the above arrangement, the fan can be used to convey air to the mixed slurry in the oxidation tank through the conveying pipeline, which is conducive to the complete oxidation of magnesium sulfite into magnesium sulfate solution without using an oxidizing reagent.

[0029] In the embodiment, the discharge end of the conveying pipeline is provided with a plurality of aeration holes. The above arrangement can accelerate the oxidation of magnesium sulfite.

[0030] In the embodiment, the device for preparing an aqueous proton battery electrolyte based on a magnesium method flue gas desulfurization by-product further comprises a solid-liquid separation unit, the discharge end of the impurity removal unit 2 is in communication with the feed end of the solid-liquid separation unit, and the discharge end of the solid-liquid separation unit is in communication with the feed end of the electrolyte preparation unit 3.

[0031] In the embodiment, the oxidation unit 1, the impurity removal unit 2, and the electrolyte preparation unit 3 all comprise stirring devices for realizing the mixing and dispersion of materials.

[0032] In a third aspect, the present application provides a water-based proton battery, which comprises the water-based proton battery electrolyte provided by the first aspect of the present application and a negative electrode sheet; wherein the negative electrode sheet comprises a molybdenum trioxide negative active material.

[0033] In the present embodiment, the preparation method of the molybdenum trioxide comprises: mixing and reacting molybdenum powder and hydrogen peroxide, and then obtaining the molybdenum trioxide through aging, drying, grinding and calcination after the reaction is completed.

[0034] The mass fraction of the hydrogen peroxide is 25% to 30%, and the dosage ratio of the molybdenum powder to the hydrogen peroxide is 1 g to (8 to 10) mL.

[0035] The reaction is complete when the reaction system no longer produces bubbles, and the solution is completely clear and free of solid residues after standing.

[0036] The aging is performed at room temperature for 10 to 14 hours in a closed condition.

[0037] The drying is performed at a temperature of 50 to 80 °C for 10 to 16 hours.

[0038] The calcination process comprises: first calcining at 200 to 300 °C for 2 to 4 hours, and then calcining at 450 to 550 °C for 1 to 3 hours, with a heating rate of 3 to 8 °C / min and an air atmosphere.

[0039] Example 1 (1) Using the by-product of the magnesium-based flue gas desulfurization (the composition and content of the dry material are shown in Table 1) as the raw material, the by-product of the magnesium-based flue gas desulfurization was mixed with water at a liquid-solid mass ratio of 3:1, and was dispersed by stirring for 5 minutes. Sulfuric acid (mass fraction of 98%) was used to adjust the pH value of the solution to 5.0, and a mixed slurry was obtained.

[0040] (2) Air was sent to the mixed slurry in the oxidation tank through a conveying pipeline using a fan, the air flow was 0.1 L / min, the oxidation temperature was 45 °C, and the oxidation time was 50 min, so that the magnesium sulfite was completely oxidized to magnesium sulfate, and an oxidation slurry was obtained. The outlet of the conveying pipeline was provided with a plurality of aeration holes to accelerate the oxidation of the magnesium sulfite.

[0041] (3) The oxidation slurry was sent to a stirring reactor, and Mg2CO3 was added under stirring at a molar ratio of carbonate ions to calcium ions of 1.3:1, and the solution was stirred at room temperature for 5 min, so that Ca 2+ reacted with CO3 2- to generate CaCO3 precipitate; then Mg(OH)2 was added to adjust the pH value to 5.2, and the solution was stirred at room temperature for 5 min, so that Fe 3+The Fe(OH)3 is precipitated. Finally, the material liquid is sent into a filter (filter membrane pore size is 0.45 μm) by a diaphragm pump for solid-liquid separation, and the obtained filtrate is a high-purity magnesium sulfate solution (composition and content are shown in Table 2).

[0042] (4) The high-purity magnesium sulfate solution and the sulfuric acid solution are used to prepare an aqueous proton battery electrolyte, and water and magnesium sulfate can be added as needed during the preparation. In the aqueous proton battery electrolyte, the concentration of sulfuric acid is 2 mol / L, and the concentration of magnesium sulfate is 2 mol / L.

[0043] Table 1 Composition and content of dry material of by-product of magnesium method flue gas desulfurization

[0044] Table 2 Composition and content of high-purity magnesium sulfate solution

[0045] Example 2 (1) The by-product of magnesium method flue gas desulfurization (composition and content of dry material are shown in Table 1) is used as raw material, and the by-product of magnesium method flue gas desulfurization is mixed with water at a liquid-solid mass ratio of 4:1, stirred and dispersed for 5 min, and the pH value of the solution is adjusted to 5.0 using sulfuric acid (mass fraction is 98%) to obtain a mixed slurry.

[0046] (2) Air is sent to the mixed slurry in the oxidation tank through a conveying pipeline by a fan, the air flow is 0.1 L / min, the oxidation temperature is 35°C, and the oxidation time is 50 min, so that the magnesium sulfite is completely oxidized to magnesium sulfate to obtain an oxidation slurry. The outlet of the conveying pipeline is provided with a plurality of aeration holes to accelerate the oxidation of magnesium sulfite.

[0047] (3) The oxidation slurry is sent to a stirring reactor, Mg2CO3 is added under stirring at a molar ratio of carbonate ions to calcium ions of 1.4:1, and stirred at room temperature for 10 min, so that Ca 2+ reacts with CO3 2- to generate CaCO3 precipitate; then Mg(OH)2 is added to adjust the pH value to 5.2, and stirred at room temperature for 10 min, so that Fe 3+ is precipitated in the form of Fe(OH)3. Finally, the material liquid is sent into a filter (filter membrane pore size is 0.45 μm) by a diaphragm pump for solid-liquid separation, and the obtained filtrate is a high-purity magnesium sulfate solution (composition and content are shown in Table 3).

[0048] (4) The high-purity magnesium sulfate solution and the sulfuric acid solution are used to prepare an aqueous proton battery electrolyte, and water and magnesium sulfate can be added as needed during the preparation. In the aqueous proton battery electrolyte, the concentration of sulfuric acid is 2 mol / L, and the concentration of magnesium sulfate is 3 mol / L.

[0049] Table 3 Composition and content of high-purity magnesium sulfate solution

[0050] Comparative Example 1 Directly use 2 mol / L sulfuric acid solution as the electrolyte of aqueous proton battery.

[0051] Comparative Example 2 Compared with Example 1, the only difference is that the analytical pure magnesium sulfate solution is used to replace the high-purity magnesium sulfate solution in step (4).

[0052] Performance test (1) Preparation of molybdenum trioxide powder MoO3 was prepared by sol-gel method. First, 0.6 g of molybdenum powder was placed in a beaker, and the beaker was placed in an ice water bath. Under continuous stirring, 5 mL of H2O2 (30 wt%) was slowly added dropwise into the beaker. When the reaction system no longer produced bubbles, and the solution was completely clear and no solid residue was observed, the reaction was considered complete, and a clear yellow solution was obtained. Then, the beaker was tightly covered with plastic wrap, and the sol was aged at room temperature for 12 h. Subsequently, the sol was transferred to a 60 °C constant temperature drying oven for drying for 12 h. After drying, the obtained sample was ground in a mortar for 10 min to obtain a yellow powder. 0.2 g of the powder was placed in a porcelain boat, and the porcelain boat was placed in a tube furnace. The temperature rising rate of the tube furnace was set to 5 °C / min, and the preheating treatment was carried out by first heating to 250 °C and maintaining for 3 h under air atmosphere. After the preheating treatment was completed, the temperature was continued to rise to 500 °C and maintained for 2 h, and the final powder was the MoO3 sample.

[0053] (2) Preparation of electrode sheet The active material molybdenum trioxide (MoO3), acetylene black, and polyvinylidene fluoride (PVDF) were placed in a mortar in a mass ratio of 6:3:1, and manually ground for 1.5 h to mix uniformly. Subsequently, nitrogen methyl pyrrolidone (NMP) was added in a solid-liquid ratio of 0.25 g:1 mL, and stirred and mixed using a doctor blade to form a uniform slurry, which was then applied to a carbon-coated titanium mesh (100 mesh) of 1 cm×2 cm. The active material was controlled to have a coating area of 1 cm 2 , and the coating amount was 1.5 mg. Then, the titanium mesh with the coated sample was dried in a 60 °C electric heating air drying oven for 12 h to obtain a molybdenum trioxide-based electrode sheet.

[0054] Activated carbon, acetylene black, and PVDF were placed in a mortar at a mass ratio of 6:3:1 and manually ground for 1 h to mix them evenly. Subsequently, nitrogen-methylpyrrolidone (NMP) was added at a solid-liquid ratio of 0.25 g:1 mL and stirred with a spatula to form a uniform slurry. The slurry was then applied to a 1 cm × 2 cm carbon-coated titanium mesh (100 mesh). The activated carbon coating area was 1.25 cm. 2 The coating amount was 2 mg, and the carbon-based electrode sheet was obtained by drying in an electric heated forced air drying oven at 60 °C for 12 h.

[0055] (3) Half-cell assembly and testing The half-cell employed a molybdenum trioxide-based electrode as the working electrode, a silver-silver chloride electrode as the reference electrode, and a carbon-based electrode as the counter electrode. The electrolytes used were the various aqueous proton battery electrolytes prepared in the aforementioned examples and comparative examples. After assembly, electrochemical testing was performed using cyclic voltammetry (scan rates of 1 to 10 mV / s) and constant current charge-discharge methods using a Chenhua CHI760E electrochemical workstation to investigate the cycling stability and rate performance of the aqueous proton battery electrolyte.

[0056] See also Figures 2-3 ,pass Figures 2-3 It can be seen that the XRD diffraction peak of MoO3 prepared in the present invention is highly consistent with the standard card of α-MoO3, and the diffraction peak is sharp and has no obvious miscellaneous peaks, indicating that molybdenum trioxide has a good degree of polymerization at 500°C and its grain size reaches the micron level.

[0057] See also Figures 4-5 ,pass Figures 4-5 It can be seen that the CV curve peaks of molybdenum trioxide in the two electrolytes are almost unchanged, indicating that although there is Mg in the 2 M H2SO4 + 2M MgSO4 electrolyte, 2+ , but it does not participate in the ion storage process. In addition, at a scan rate of 10 mV / s, the CV curve corresponding to the 2 M H2SO4 + 2 M MgSO4 electrolyte is more complete, indicating that this electrolyte has a better ion conductivity rate.

[0058] See also Figure 6 ,pass Figure 6 It can be seen that at a current density of 20 A / g, the specific capacity of molybdenum trioxide in 2 M H2SO4+2 MMgSO4 electrolyte is as high as 160 mAh / g, while in 2 M H2SO4 electrolyte it is only 149 mAh / g, indicating that the electrolyte of the embodiment of the present application has better rate performance.

[0059] See also Figure 7 ,pass Figure 7It can be seen that after 500 cycles at a current density of 5 A / g, the capacity retention rate of molybdenum trioxide in 2M H2SO4+2M MgSO4 electrolyte, 2M H2SO4+3M MgSO4 electrolyte is 72% and 84% respectively, and in the traditional 2M H2SO4 electrolyte is only 25%, which shows that the electrolyte of the embodiment of the application has more excellent cycle performance. At the same time, the capacity retention rate of molybdenum trioxide in 2M H2SO4+2M MgSO4- analytical pure electrolyte is 77.2%, which shows that the electrolyte prepared by the method of the application has performance comparable to that of the electrolyte prepared by analytical pure, realizing the conversion of industrial solid waste to high value-added products.

[0060] Compared with the prior art, the beneficial effects of the application include: (1) High-value utilization of solid waste. Breakthroughly using magnesium method flue gas desulfurization by-product as raw material, realizing the conversion of industrial solid waste to high value-added products.

[0061] (2) Process innovation. An integrated process of "forced oxidation-chemical precipitation-filtration purification" is adopted, magnesium sulfite is converted into magnesium sulfate by forced oxidation, calcium ions and iron ions are removed by magnesium carbonate and magnesium hydroxide in steps, and high-purity magnesium sulfate solution is obtained as electrolyte additive.

[0062] (3) Performance improvement. Mg 2+ Optimize the performance of the electrolyte through double action mechanism. On the one hand, by reducing the content of free water molecules in the solution, the local salt concentration is improved, the corrosion of free water is inhibited, and the cycle performance of the battery is enhanced; on the other hand, by enhancing the ionic conductivity of the electrolyte, the rate performance of the battery is significantly improved.

[0063] The specific embodiments of the application described above do not constitute a limitation on the scope of protection of the application. Any various other corresponding changes and modifications made according to the technical concept of the application shall be included in the protection scope of the claims of the application.

Claims

1. A method for preparing aqueous proton battery electrolyte based on magnesium-based flue gas desulfurization byproducts, characterized in that: The following steps are involved: The by-products of magnesium-based flue gas desulfurization are oxidized and impurity-removed to obtain a high-purity magnesium sulfate solution; The high-purity magnesium sulfate solution and sulfuric acid solution are mixed to obtain an aqueous proton battery electrolyte; wherein, The components of the magnesium-based flue gas desulfurization by-products include magnesium sulfate and magnesium sulfite.

2. The method for preparing aqueous proton battery electrolyte based on magnesium-based flue gas desulfurization byproducts according to claim 1, characterized in that: The step of performing oxidation treatment and impurity removal treatment on the magnesium-based flue gas desulfurization byproduct to obtain a high-purity magnesium sulfate solution comprises: Mixing the magnesium flue gas desulfurization byproduct and water, and adjusting the pH to 4.5-5.5 to obtain a mixed slurry; introducing air into the mixed slurry to carry out an oxidation reaction to obtain an oxidized slurry; The oxidizing slurry and magnesium carbonate are mixed to carry out a first precipitation reaction, and then magnesium hydroxide is added to carry out a second precipitation reaction. After solid-liquid separation, a high-purity magnesium sulfate solution is obtained.

3. The method for preparing aqueous proton battery electrolyte based on magnesium-based flue gas desulfurization byproducts according to claim 2, characterized in that: In the process of mixing the magnesium flue gas desulfurization byproduct and water, the liquid-to-solid mass ratio is (2-4):1; Use 90% to 98% sulfuric acid to adjust the pH to 4.5 to 5.5; During the oxidation reaction, the air flow rate is 0.1-3 L / min, the oxidation temperature is 35-55°C, and the oxidation time is 10-180 min.

4. The method for preparing aqueous proton battery electrolyte based on magnesium-based flue gas desulfurization byproducts according to claim 2, characterized in that: During the first precipitation reaction, magnesium carbonate is added to control the molar ratio of carbonate ions to calcium ions to be (1.1-1.5):1; The temperature of the first precipitation reaction is room temperature, and the time of the first precipitation reaction is 5 to 10 minutes.

5. The method for preparing aqueous proton battery electrolyte based on magnesium-based flue gas desulfurization byproducts according to claim 2, characterized in that: During the second precipitation reaction, magnesium hydroxide is added to control the pH value to be ≥5.0; The temperature of the second precipitation reaction is room temperature, and the time of the second precipitation reaction is 5 to 10 minutes.

6. The method for preparing aqueous proton battery electrolyte based on magnesium-based flue gas desulfurization byproducts according to claim 1, characterized in that: In the high-purity magnesium sulfate solution, the concentration of magnesium sulfate is 1-3 mol / L.

7. The method for preparing aqueous proton battery electrolyte based on magnesium-based flue gas desulfurization byproducts according to claim 1, characterized in that: In the aqueous proton battery electrolyte, the concentration of sulfuric acid is 1-3 mol / L, and the concentration of magnesium sulfate is 1-3 mol / L.

8. A device for preparing aqueous proton battery electrolyte based on magnesium-based flue gas desulfurization byproducts, characterized in that: It includes an oxidation unit, an impurity removal unit and an electrolyte preparation unit; wherein, The discharge end of the oxidation unit is connected to the feed end of the impurity removal unit, and the discharge end of the impurity removal unit is connected to the feed end of the electrolyte preparation unit; The device for preparing aqueous proton battery electrolyte based on magnesium-based flue gas desulfurization byproducts is used to perform the method for preparing aqueous proton battery electrolyte based on magnesium-based flue gas desulfurization byproducts as described in any one of claims 1 to 7.

9. The device for preparing aqueous proton battery electrolyte based on magnesium-based flue gas desulfurization byproducts according to claim 8, characterized in that: The oxidation unit includes an oxidation tank and a blower, the oxidation tank and the blower are connected through a conveying pipe, and a plurality of aeration holes are provided at the discharge end of the conveying pipe; The device for preparing aqueous proton battery electrolyte based on magnesium-based flue gas desulfurization byproducts further includes: a solid-liquid separation unit, the discharge end of the impurity removal unit is connected to the feed end of the solid-liquid separation unit, and the discharge end of the solid-liquid separation unit is connected to the feed end of the electrolyte preparation unit; The oxidation unit, the impurity removal unit and the electrolyte preparation unit all include a stirring device.

10. An aqueous proton battery, characterized in that: The aqueous proton battery comprises the aqueous proton battery electrolyte according to any one of claims 1 to 7 and a negative electrode plate; wherein the negative electrode plate comprises molybdenum trioxide negative electrode active material.

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