A method for separating perovskite and preparing battery material based on blast furnace titanium slag

Abstract

The present application relates to the technical field of titanium slag separation, in particular to a method for separating perovskite and preparing battery material based on blast furnace titanium slag; the present application reconstructs silicate mineral phase in blast furnace titanium slag, so that it can be completely dissolved by acid, at the same time, low-valence titanium in the silicate mineral phase is oxidized to high-valence titanium and enriched in the perovskite phase, thereby realizing the separation and purification of CaTiO3 in the titanium slag; further, the present application loads porous network structure sodium titanate hydrate and calcium titanate hydrate on the surface of the separated and purified CaTiO3, which can enhance the bonding strength of CaTiO3 and polyethylene diaphragm, thereby improving the thermal stability of the lithium battery solid electrolyte interface layer prepared based on high-titanium slag. In summary, the present application not only provides a new method for separating and purifying blast furnace titanium slag, promotes the high-value utilization of blast furnace titanium slag, but also provides a new idea and method for the preparation of lithium battery solid electrolyte interface layer, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of titanium slag separation technology, specifically to a method for separating perovskite from blast furnace titanium slag and preparing battery materials. Background Technology

[0002] Blast furnace titanium slag contains a high proportion (25-85%) of titanium dioxide (TiO2), making it an important raw material for the preparation of titanium-based products. However, in addition to titanium dioxide, blast furnace titanium slag also contains a large number of impurities. The presence of these impurities results in poor quality of titanium-based products prepared from blast furnace titanium slag, thus seriously affecting the economic value of blast furnace titanium slag. Therefore, developing novel blast furnace titanium slag separation and purification technologies to improve the purity and quality of titanium-based products and achieve high-value utilization of blast furnace titanium slag is of significant economic importance.

[0003] Meanwhile, with the rapid development of electric vehicles, smart grid energy storage devices, and portable electronic devices, higher demands are being placed on the energy density and range of batteries. Lithium metal, due to its advantages such as high energy density, low operating potential, and low density, has been considered one of the most ideal anode materials. However, during cycling, lithium metal batteries are prone to uncontrolled and harmful lithium dendrite growth due to uneven lithium deposition and repeated damage and reconstruction of the fragile solid electrolyte interphase (SEI) layer. This not only leads to a decrease in coulombic efficiency and rapid degradation of cycle performance, but may even cause safety issues such as membrane puncture. While widely used polyethylene (PE) membranes have a certain application basis, their wettability is poor, and they are easily penetrated by lithium dendrites during cycling, causing membrane failure. Therefore, finding composite membrane materials suitable for high-energy-density lithium metal batteries has become an urgent priority for improving lithium metal battery performance.

[0004] To address the aforementioned issues, some studies have attempted to use PE composite membranes to solve the ion transport problem (e.g., "Interface Treatment Based on Calcium Carbonate and Its Mechanism in Perovskite Solar Cells"). The core idea of ​​these studies is to utilize perovskite-type CaTiO3 as a coating material or coating composite material to prepare narrow bandgap oxides with better lithiophilicity, thereby improving the performance of the electrolyte interface layer in lithium batteries.

[0005] However, in existing technologies, perovskite-type CaTiO3 typically needs to be purchased separately in pure form, and the demand is large and the purity requirements are high, leading to high material costs. To address this issue, the inventors proposed an innovative approach: if CaTiO3 with the properties required for lithium-ion battery modification can be separated from blast furnace titanium slag, the cost of membrane preparation will be significantly reduced, and a new opportunity will be provided for the high-value utilization of blast furnace titanium slag. Although blast furnace titanium slag contains a certain amount of CaTiO3, it also contains a large number of impurities, and the morphology of CaTiO3 in the titanium slag does not meet the standards required for lithium-ion battery modification, therefore it cannot be used directly.

[0006] To overcome this technical challenge, the inventors have for the first time proposed a process for the separation and modification of CaTiO3 in blast furnace titanium slag. Through systematic analysis of the composition of blast furnace titanium slag, the inventors designed a targeted separation process to extract high-purity CaTiO3 material that meets the requirements for lithium battery modification. Furthermore, the inventors proposed a modification method that adjusts the morphology of CaTiO3 to better suit the requirements of the solid electrolyte interface layer in lithium batteries, thereby significantly improving the cycle performance and safety of lithium batteries. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a method for separating perovskite from blast furnace titanium slag and preparing battery materials. Based on compositional analysis of blast furnace titanium slag, the inventors designed a separation process targeting CaTiO3 and silicates, further improving the microstructure of the separated CaTiO3 and enhancing its bonding strength with the polyethylene separator, thereby improving the thermal stability of the solid electrolyte interface layer in lithium batteries. The details are as follows:

[0008] S1. Removal of impurities from titanium slag;

[0009] S1-1. The initial blast furnace titanium slag is ball-milled, then ultrasonically cleaned with anhydrous ethanol and deionized water in sequence, and then completely dried and ground into powder for later use to obtain the cleaned titanium slag.

[0010] S1-2. The cleaned titanium slag and MnO are placed in a reactor and ball-milled to mix evenly with Mn:Ti in a molar ratio of 3 to 4:8. After mixing evenly, the mixture is placed in the reactor and heated from room temperature to 1500℃ at a heating rate of 3℃ / min and held at that temperature for 1 to 1.5 hours. Then, the temperature is lowered at a cooling rate of 1 to 2℃ / min until it reaches 1250℃. The mixture is then quenched in a quenching agent to obtain the quenched slag after perovskite precipitation.

[0011] S1-3. The quenched slag is successively washed with anhydrous ethanol, ball-milled, dried once, acid-leached, filtered, washed with deionized water and dried a second time to obtain CaTiO3 material.

[0012] Note: Desilication is a difficult point in the wet resource utilization process of high-silicon blast furnace titanium slag because the dissolved silica molecules have complex polymerization and gelation behavior. This invention uses perovskite (CaTiO3) in blast furnace titanium slag as the target component and achieves the reconstruction and separation of silicate minerals and the enrichment of CaTiO3 through acid leaching treatment.

[0013] S2. Preparation of CaTiO3 composite membrane;

[0014] S2-1. The CaTiO3 material is isostatically pressed at 6MPa into thin sheets with a thickness of 0.7-1mm to obtain CaTiO3 thin sheets;

[0015] S2-2. Mix calcium glycerophosphate, Ca(CH3COO)2, EDTA-2Na and NaOH in deionized water until homogeneous to obtain a mixed solution;

[0016] Let n be the multiplier and n∈R + The amount of calcium glycerophosphate added to the mixture is 10n g, the amount of Ca(CH3COO)2 added is n[11.5,12.8] g, the amount of EDTA-2Na added is n[14.3,15.5] g, the amount of NaOH added is n[9,10] g, and the amount of deionized water added is n[1,1.2] L.

[0017] S2-3, S2-3, The mixture in S2-2 is placed into the arc oxidation equipment as the electrolyte, a stainless steel tank is used as the working cathode, and the CaTiO3 sheet in S2-1 is used as the working anode. Finally, the mixture is oxidized by electricity to obtain porous network CaTiO3.

[0018] S2-4. The porous mesh CaTiO3 is completely immersed in NaOH solution for etching, and then crushed to obtain CaTiO3 composite material;

[0019] S2-5. After the CaTiO3 composite material and the adhesive are stirred and mixed evenly, they are sprayed evenly on both sides of the PE membrane and then dried to obtain the CaTiO3 composite membrane.

[0020] Furthermore, the parameters for ultrasonic cleaning in S1-1 are: ultrasonic frequency of 40-50 kHz, cleaning temperature of 45-55℃, and cleaning time of 20-30 min.

[0021] Furthermore, the parameters for ball milling in S1-2 are: ball mill speed of 200-250 r / min, and ball milling time of 1-1.5 h;

[0022] The quenching agent in S1-2 is a mixture of 20% NaNO3 and 25% Na2CO3 by mass in a volume ratio of 2 to 4:1.

[0023] Note: The choice of quenching temperature and quenching agent will both lead to changes in the microstructure of perovskite in the quenched slag; the quenching rates of oil quenching and water quenching are different, with oil quenching having a slower cooling rate than water quenching. Therefore, the surface of titanium slag is smooth after oil quenching, while it is loose after water quenching. Based on the adhesion strength of other components on the perovskite in subsequent processes, water quenching is preferred here; it is worth noting that the content of silicon impurities in the titanium slag after oil quenching is lower than that after water quenching; the water quenching process is chosen here to take into account the influence of the perovskite (CaTiO3) morphology on the strength of the subsequent composite membrane.

[0024] Furthermore, the parameters for acid leaching in S1-3 are as follows: leaching temperature is 25℃, leaching solution is hydrochloric acid with a mass fraction of 10%, solid-liquid ratio is 1:15~20, leaching time is 1h, and stirring speed during acid leaching is 400~450r / min.

[0025] The parameters for ball milling in S1-3 are: ball mill speed of 200-250 r / min, and ball milling time of 1-1.5 h;

[0026] The parameters for both primary and secondary drying in S1-3 are: drying temperature of 100℃ and drying time of 30-40 min.

[0027] Explanation: By adding a special quenching agent, low-valence titanium (+2, +3) present in the silicate mineral phase is oxidized to +4 and enriched in the perovskite phase. The silicate phase, which cannot be completely dissolved by acid, is reconstructed to form a silicate that can be completely dissolved by acid: Na. 1.8 (Mg 0.9 Si 1.1 O4), Na 1.8 (Mg 1.75 Si 1.2 O4), Na 1.8 (Mg 1.5 Si 0.55 O4).

[0028] Furthermore, the parameters for electro-oxidation in S2-3 are: voltage of 300-500V, energizing time of 5-10min, current frequency of 600-700Hz, and duty cycle of 5-6%.

[0029] Description: A calcium phosphate oxide coating was deposited on CaTiO3 sheets using micro-arc oxidation technology. The coating has a uniform porous structure, and as the voltage increases, a rutile phase is formed in the coating, the micropore size increases, the pore density decreases, and the interface bonding with CaTiO3 is good.

[0030] The etching process described in S2-4 is further as follows:

[0031] First, the porous CaTiO3 network was completely immersed in a NaOH solution with a concentration of 1–3 mol / L. The etching temperature was 50–55℃, and the etching time was 24 h. Then, the temperature was increased to 500–550℃ at a heating rate of 10℃ / min and held at that temperature for 1–1.5 h.

[0032] Explanation: Alkali etching causes the calcium phosphate oxide coating surface to dissolve, and the TiO2 and OH in the coating react... - The reaction of ions forms HTiO3 - Ions, HTiO3 - The ions further react with Na in the alkaline solution + Ionic reactions form a porous network morphology of sodium titanate hydrate; subsequent heat treatment alters the surface morphology of the coating, causing the sodium titanate hydrate to dehydrate and crystallize to form Na₂Ti₉O. 19 Meanwhile, HTiO3 - Ions further attract Ca dissolved in the alkaline solution 2+ Ions form porous, honeycomb-like calcium titanate hydrates on the coating surface, which greatly enhances the bonding strength with the polyethylene membrane.

[0033] Furthermore, the adhesive in S2-5 is a mixture of polyvinylidene fluoride and 1-methyl-2-pyrrolidone;

[0034] Let n be the multiplier and n∈R + Then, the amount of CaTiO3 composite material added in S2-5 is 5n g, the amount of polyvinylidene fluoride added is n[1,1.5] g, and the amount of 1-methyl-2-pyrrolidone added is n[10,15] mL.

[0035] The drying parameters in S2-5 are: drying temperature of 60-70℃ and drying time of 12h.

[0036] In another aspect, a method for preparing a lithium battery based on the above-mentioned CaTiO3 composite separator is also provided:

[0037] S3-1. Use a punching machine to cut the CaTiO3 composite diaphragm in S2 into round pieces with a diameter of 16mm to obtain CaTiO3 composite diaphragm sheets.

[0038] S3-2, LiNi as the electrode active material 0.5 Mn 1.5 O4, acetylene black as a conductive agent and polyvinylidene fluoride as a binder are mixed evenly in 1-methyl-2-pyrrolidone to prepare a slurry.

[0039] Let n be the multiplier and n∈R + Then LiNi in S3-3 0.5Mn 1.5 The amount of O4 added is 8n g, the amount of acetylene black added is n[1,1.5] g, the amount of polyvinylidene fluoride added is n[1,1.5] g, and the amount of 1-methyl-2-pyrrolidone added is n[10,15] mL.

[0040] S3-3. Apply the above slurry onto aluminum foil using a scraping method, then dry it at 80°C for 6-8 hours, and finally cut it into round pieces with a diameter of 10 mm using a punching machine to obtain electrode sheets.

[0041] S3-4. Prepare an argon atmosphere glove box with water and oxygen content both less than 0.1ppm. In the glove box, assemble the lithium battery components in the following order: negative electrode shell, electrode sheet, CaTiO3 composite separator sheet, 85μL electrolyte, 10mm lithium sheet, gasket, spring sheet, and positive electrode shell. Finally, seal the lithium battery with a sealing machine and store it for later use.

[0042] The beneficial effects of this invention are:

[0043] This invention proposes a method for separating CaTiO3 from blast furnace titanium slag and using it to prepare a highly stable solid electrolyte interface layer for lithium batteries. This method promotes the high-value utilization of blast furnace titanium slag and provides new ideas and methods for the preparation of solid electrolyte interface layers for lithium batteries. The low cost of blast furnace titanium slag can significantly reduce the price of CaTiO3 products, making them more competitive in the market. At the same time, the microstructure of CaTiO3 is modified to enhance its bonding strength with polyethylene membranes and improve the thermal stability of the solid electrolyte interface layer for lithium batteries. Attached Figure Description

[0044] Figure 1 These are SEM images of the samples prepared in Example 1;

[0045] Figure 2 This is a cross-sectional SEM image of the sample prepared in Example 1;

[0046] Figure 3 This is a graph showing the effect of voltage on the amount of Mn penetrating into the membrane interface in the experimental example.

[0047] Figure 4 This is the overpotential diagram of the battery assembled with PE membrane and CaTiO3 composite membrane in the experimental example;

[0048] Figure 5 This is a graph showing the capacity change of a battery assembled with a PE membrane and a CaTiO3 composite membrane during cycle discharge in the experimental example. Detailed Implementation

[0049] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0050] Example 1: This example describes a method for separating perovskite from blast furnace titanium slag and preparing battery materials.

[0051] S1. Removal of impurities from titanium slag;

[0052] S1-1. The initial blast furnace titanium slag is ball-milled, then ultrasonically cleaned with anhydrous ethanol and deionized water in sequence, and then completely dried and ground into powder for later use to obtain the cleaned titanium slag.

[0053] The parameters for ultrasonic cleaning are: ultrasonic frequency of 40kHz, cleaning temperature of 45℃, and cleaning time of 20min.

[0054] S1-2. The cleaned titanium slag and MnO are placed in the reactor and ball-milled to mix evenly in a molar ratio of Mn:Ti = 3:8. After mixing evenly, the mixture is placed in the reactor and heated from room temperature to 1500℃ at a heating rate of 3℃ / min and held at that temperature for 1h. Then, the temperature is lowered at a cooling rate of 1℃ / min until it reaches 1250℃. The mixture is then quenched in a quenching agent to obtain the quenched slag after perovskite precipitation.

[0055] The parameters for the ball mill are: ball mill speed 200 r / min, ball milling time 1 h;

[0056] The quenching agent is a mixture of 20% NaNO3 and 25% Na2CO3 by mass in a volume ratio of 2:1.

[0057] S1-3. The quenched slag is successively washed with anhydrous ethanol, ball-milled, dried once, acid-leached, filtered, washed with deionized water and dried a second time to obtain CaTiO3 material.

[0058] The parameters for acid leaching are as follows: leaching temperature is 25℃, leaching solution is 10% hydrochloric acid by mass, solid-liquid ratio is 1:15, leaching time is 1h, and stirring speed during acid leaching is 400r / min.

[0059] The parameters for ball milling in S1-3 are: ball mill speed is 200 r / min, and ball milling time is 1 h;

[0060] The parameters for both primary and secondary drying are: drying temperature 100℃, drying time 30min;

[0061] S2. Preparation of CaTiO3 composite membrane;

[0062] S2-1. The CaTiO3 material is isostatically pressed at 6MPa into a sheet with a thickness of 0.7mm to obtain CaTiO3 sheet;

[0063] S2-2. Mix calcium glycerophosphate, Ca(CH3COO)2, EDTA-2Na and NaOH in deionized water until homogeneous to obtain a mixed solution;

[0064] The amount of calcium glycerophosphate added is 10g, the amount of Ca(CH3COO)2 added is 11.5g, the amount of EDTA-2Na added is 14.3g, the amount of NaOH added is 9g, and the amount of deionized water added is 1L.

[0065] S2-3. The mixture in S2-2 is placed into an arc oxidation device (which is a product of existing technology) as an electrolyte. A stainless steel tank is used as the working cathode, and the CaTiO3 sheet in S2-1 is used as the working anode. Finally, the mixture is oxidized by electricity to obtain porous network CaTiO3.

[0066] The parameters for electro-oxidation are: voltage 300V, energizing time 5min, current frequency 600Hz, and duty cycle 5%.

[0067] S2-4. The porous network CaTiO3 is completely immersed in a 1 mol / L NaOH solution, etched at 50°C for 24 hours; then heated to 500°C at a heating rate of 10°C / min and held for 1 hour. Finally, the CaTiO3 composite material is obtained by crushing.

[0068] S2-5. After mixing the CaTiO3 composite material and the adhesive evenly, spray it evenly on both sides of the PE (KK1640) separator, and then dry it to obtain the CaTiO3 composite separator.

[0069] The adhesive is a mixture of polyvinylidene fluoride and 1-methyl-2-pyrrolidone;

[0070] The amount of CaTiO3 composite material added is 5g, the amount of polyvinylidene fluoride added is 1g, and the amount of 1-methyl-2-pyrrolidone added is 10mL.

[0071] The drying parameters are: drying temperature 60℃, drying time 12h.

[0072] Example 2: This example describes a method for separating perovskite from blast furnace titanium slag and preparing battery materials.

[0073] S1. Removal of impurities from titanium slag;

[0074] S1-1. The initial blast furnace titanium slag is ball-milled, then ultrasonically cleaned with anhydrous ethanol and deionized water in sequence, and then completely dried and ground into powder for later use to obtain the cleaned titanium slag.

[0075] The parameters for ultrasonic cleaning are: ultrasonic frequency of 50kHz, cleaning temperature of 55℃, and cleaning time of 30min.

[0076] S1-2. The cleaned titanium slag and MnO are placed in the reactor and ball-milled to mix evenly with Mn:Ti in a molar ratio of 4:8. After mixing evenly, the mixture is placed in the reactor and heated from room temperature to 1500℃ at a heating rate of 3℃ / min and held at that temperature for 1.5h. Then, the temperature is lowered at a cooling rate of 2℃ / min until it reaches 1250℃. The mixture is then quenched in a quenching agent to obtain the quenched slag after perovskite precipitation.

[0077] The parameters for the ball mill are: ball mill speed 250 r / min, ball milling time 1.5 h;

[0078] The quenching agent is a mixture of 20% NaNO3 and 25% Na2CO3 by mass in a volume ratio of 4:1.

[0079] S1-3. The quenched slag is successively washed with anhydrous ethanol, ball-milled, dried once, acid-leached, filtered, washed with deionized water and dried a second time to obtain CaTiO3 material.

[0080] The parameters for acid leaching are as follows: leaching temperature is 25℃, leaching solution is 10% hydrochloric acid by mass, solid-liquid ratio is 1:20, leaching time is 1h, and stirring speed during acid leaching is 450r / min.

[0081] The parameters for ball milling in S1-3 are: ball mill speed of 250 r / min and ball milling time of 1.5 h;

[0082] The parameters for both primary and secondary drying are: drying temperature 100℃, drying time 40min;

[0083] S2. Preparation of CaTiO3 composite membrane;

[0084] S2-1. The CaTiO3 material is isostatically pressed at 6MPa into a sheet with a thickness of 1mm to obtain CaTiO3 sheet.

[0085] S2-2. Mix calcium glycerophosphate, Ca(CH3COO)2, EDTA-2Na and NaOH in deionized water until homogeneous to obtain a mixed solution;

[0086] The amount of calcium glycerophosphate added is 10g, the amount of Ca(CH3COO)2 added is 12.8g, the amount of EDTA-2Na added is 15.5g, the amount of NaOH added is 10g, and the amount of deionized water added is 1.2L.

[0087] S2-3. The mixture in S2-2 is placed into an arc oxidation device (which is a product of existing technology) as an electrolyte. A stainless steel tank is used as the working cathode, and the CaTiO3 sheet in S2-1 is used as the working anode. Finally, the mixture is oxidized by electricity to obtain porous network CaTiO3.

[0088] The parameters for electro-oxidation are: voltage 500V, energizing time 10min, current frequency 700Hz, and duty cycle 6%.

[0089] S2-4. The porous network CaTiO3 is completely immersed in a 3 mol / L NaOH solution, etched at 55℃ for 24 h; then heated to 550℃ at a heating rate of 10℃ / min and held for 1.5 h, and finally crushed to obtain the CaTiO3 composite material.

[0090] S2-5. After mixing the CaTiO3 composite material and the adhesive evenly, spray it evenly on both sides of the PE (KK1640) separator, and then dry it to obtain the CaTiO3 composite separator.

[0091] The adhesive is a mixture of polyvinylidene fluoride and 1-methyl-2-pyrrolidone;

[0092] The amount of CaTiO3 composite material added is 5n g, the amount of polyvinylidene fluoride added is 1.5 g, and the amount of 1-methyl-2-pyrrolidone added is 15 mL.

[0093] The drying parameters are: drying temperature 70℃, drying time 12h.

[0094] Experimental Example: The description of this experimental example is based on the scheme described in Example 1, and aims to clarify the relationship between the process parameters of the present invention and the performance of the finished product.

[0095] 1. Test of Mn penetration in arc oxidation interface

[0096] Mn doping significantly induces the ferroelectricity of CaTiO3 and enhances its electrochemical performance. Therefore, the Mn content at the interface reflects the electrochemical properties of the coating interface, and the amount of Mn doping is related to the voltage during arc oxidation. Figure 1 The relationship shown.

[0097] pass Figure 3The data shows that as the voltage increases to above 250V, the Mn content increases, then slows down at 330V, and reaches a low point at 350V, where the Mn / Ca ratio is the lowest. However, as the voltage increases to 450V, the Mn content increases again, and the Mn / Ca ratio increases again. This indicates that by adjusting the voltage during arc oxidation, the Mn / Ca content ratio at the coating interface can be controlled.

[0098] 2. Thermal stability test of solid electrolyte interface layer in lithium battery

[0099] To verify the dendrite suppression effect of the CaTiO3 composite separator prepared in this invention, lithium was used as the negative electrode, and batteries were assembled using PE separators and CaTiO3 composite separators respectively. The batteries were tested at 0.2 mA cm⁻¹. -2 Current densities of 0.5, 1, 1.5, 2.0, 2.5, and 3.0 mAh cm⁻¹ were deposited on copper foil. -2 The overpotential diagram of lithium is shown in [reference needed]. Figure 4 .

[0100] A lithium copper half-cell was assembled to test the nucleation overpotential. The cell was subjected to a 0.2 mA cm⁻¹ voltage. -2 Constant current discharge was performed at a specific current density. The nucleation overpotential of the battery prepared with the CaTiO3 composite separator was 65.4 mV, which is significantly lower than that of the battery using a conventional PE separator (125.8 mV). A smaller nucleation overpotential means a lower nucleation barrier, which is conducive to uniform nucleation during the deposition process, thereby avoiding the formation of dendrites and improving the electrochemical performance of the battery.

[0101] 3. Cyclic performance test

[0102] To further investigate the dendrite suppression effect of the CaTiO3 composite separator, a 5V full cell was assembled using lithium as the reference and counter electrode and LNMO as the positive electrode. In this test, the CaTiO3 composite separator was coated on one side with the coated surface facing the lithium sheet. Its microstructure is shown in the figure below. Figure 1 , Figure 2 .

[0103] Figure 5 To assess the long-term cycling performance of full cells using CaTiO3 composite membranes and PE membranes at a current density of 2°C, the battery using the PE membrane exhibited voltage decay after 320 cycles, and its capacity decreased to 20.2 mAh / g after 500 cycles. In contrast, the full cell using the CaTiO3 composite membrane still maintained a capacity of 80.3 mAh / g after 800 cycles.

[0104] Therefore, it can be seen that CaTiO3 composite separator can significantly improve battery capacity and improve battery cycle performance.

[0105] 4. AC impedance test

[0106] In the AC impedance test, the current frequency range was 0.01Hz to 1MHz. Impedance tests were performed on batteries prepared using the two types of separators mentioned above after 20 and 50 cycles. The results showed that after 20 cycles, the interfacial impedance of the battery prepared with the ordinary PE film was 130.9Ω, while the interfacial impedance of the battery prepared with the CaTiO3 composite separator was only 49.8Ω. After 50 cycles, the interfacial impedance of the battery prepared with the ordinary PE film rapidly increased to 430.5Ω, while the resistance of the battery prepared with the CaTiO3 composite separator was only 202.6Ω, indicating that it has good interfacial stability.

Claims

1. A method for separating perovskite from blast furnace titanium slag and preparing battery materials, characterized in that, Including the following steps: S1. Removal of impurities from titanium slag; S1-1. The initial blast furnace titanium slag is ball-milled, then ultrasonically cleaned with anhydrous ethanol and deionized water in sequence, and then completely dried and ground into powder for later use to obtain the cleaned titanium slag. S1-2. The cleaned titanium slag and MnO are placed in a reactor and ball-milled to mix evenly with Mn:Ti in a molar ratio of 3 to 4:

8. After mixing evenly, the mixture is placed in the reactor and heated from room temperature to 1500°C at a heating rate of 3°C / min and held at that temperature for 1 to 1.5 hours. Then, the temperature is lowered at a cooling rate of 1 to 2°C / min until it reaches 1250°C. The mixture is then quenched in a quenching agent to obtain the quenched slag after perovskite precipitation. S1-3. The quenched slag is sequentially washed with anhydrous ethanol, ball-milled, dried once, acid-leached, filtered, washed with deionized water and dried a second time to obtain CaTiO3 material. S2. Preparation of CaTiO3 composite membrane; S2-1. The CaTiO3 material is isostatically pressed at 6MPa into a sheet with a thickness of 0.7-1mm to obtain CaTiO3 sheet; S2-2. Mix calcium glycerophosphate, Ca(CH3COO)2, EDTA-2Na and NaOH in deionized water until homogeneous to obtain a mixed solution; Let n be the multiplier and n∈R + The addition amounts of each component in the mixture are as follows: 10 ng for calcium glycerophosphate, [11.5n, 12.8n] g for Ca(CH3COO)2, [14.3n, 15.5n] g for EDTA-2Na, [9n, 10n] g for NaOH, and [1n, 1.2n] L for deionized water; S2-3. The mixture in S2-2 is placed in an arc oxidation device as an electrolyte, a stainless steel tank is used as the working cathode, and the CaTiO3 sheet in S2-1 is used as the working anode. Finally, the mixture is oxidized by electricity to obtain porous mesh CaTiO3. S2-4. The porous mesh CaTiO3 is completely immersed in NaOH solution for etching treatment, and then crushed to obtain CaTiO3 composite material; S2-5. After the CaTiO3 composite material and the adhesive are stirred and mixed evenly, they are sprayed evenly on both sides of the PE membrane and then dried to obtain the CaTiO3 composite membrane.

2. The method for separating perovskite from blast furnace titanium slag and preparing battery materials as described in claim 1, characterized in that, The ultrasonic cleaning parameters described in S1-1 are: ultrasonic frequency of 40-50 kHz, cleaning temperature of 45-55℃, and cleaning time of 20-30 min.

3. The method for separating perovskite from blast furnace titanium slag and preparing battery materials as described in claim 1, characterized in that, The parameters for ball milling described in S1-2 are: ball mill speed of 200-250 r / min, and ball milling time of 1-1.5 h; The quenching agent described in S1-2 is a mixture of 20% NaNO3 and 25% Na2CO3 by mass in a volume ratio of 2 to 4:

1.

4. The method for separating perovskite from blast furnace titanium slag and preparing battery materials as described in claim 1, characterized in that, The acid leaching parameters described in S1-3 are: leaching temperature of 25℃, leaching solution of 10% hydrochloric acid by mass, solid-liquid ratio of 1:15-20, leaching time of 1h, and stirring speed of 400-450r / min during acid leaching. The parameters for ball milling described in S1-3 are: ball mill speed of 200-250 r / min, and ball milling time of 1-1.5 h; The parameters for the primary and secondary drying described in S1-3 are: drying temperature of 100℃ and drying time of 30-40 min.

5. The method for separating perovskite from blast furnace titanium slag and preparing battery materials as described in claim 1, characterized in that, The parameters for electro-oxidation described in S2-3 are: voltage of 300-500V, energizing time of 5-10min, current frequency of 600-700Hz, and duty cycle of 5-6%.

6. The method for separating perovskite from blast furnace titanium slag and preparing battery materials as described in claim 1, characterized in that, The etching process described in S2-4 is as follows: First, the porous network CaTiO3 is completely immersed in a NaOH solution with a concentration of 1-3 mol / L, and the etching temperature is 50-55℃ for 24 hours. Then, it is heated to 500-550℃ at a heating rate of 10℃ / min and held at that temperature for 1-1.5 hours.

7. The method for separating perovskite from blast furnace titanium slag and preparing battery materials as described in claim 1, characterized in that, The adhesive described in S2-5 is a mixture of polyvinylidene fluoride and 1-methyl-2-pyrrolidone; Let n be the multiplier and n∈R + Then the addition range of CaTiO3 composite material and adhesive in S2-5 is: 5n g of CaTiO3 composite material, [1n, 1.5n] g of polyvinylidene fluoride, and [10n, 13n] mL of 1-methyl-2-pyrrolidone. The drying parameters described in S2-5 are: drying temperature of 60-70℃ and drying time of 12h.

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