A method for preparing an iron-doped ZrO2-coated magnetic lithium-ion sieve

Abstract

The application relates to a preparation method of a magnetic lithium ion sieve coated with Fe-doped ZrO2, and relates to a preparation method of a lithium ion sieve. 3+ The application creatively adopts Fe-doping and ZrO2 coating to prepare the magnetic lithium ion sieve, simultaneously reduces the dissolution loss of manganese and iron by means of metal cation ion doping and coating, realizes efficient solid-liquid separation, greatly increases the service life of the lithium ion sieve, and is applicable to lithium extraction from various lithium-containing solutions due to the acid and alkali resistance of ZrO2. The method comprises the following steps: 1, preparing FO; 2, preparing LMFO; 3, preparing ZrO2@LMFO; and 4, preparing ZrO2@HMFO. The process is simple in preparation, the dissolution loss of manganese and iron tends to be stable in multiple cycles, the magnetic separation performance is good, the process is applicable to mass production, and is helpful to the industrialization progress of lithium extraction from salt lake brine.

Description

Technical Field

[0001] This invention relates to a method for preparing lithium-ion sieves, specifically a method for preparing an iron-doped ZrO2-coated magnetic lithium-ion sieve. Background Technology

[0002] With the large-scale use of lithium-ion batteries, the global demand for lithium resources has increased dramatically. Currently, lithium extraction mainly focuses on extraction and recycling from salt lake brines, seawater, and waste lithium-ion battery solutions. Conventional lithium-ion extraction and recovery methods include precipitation, carbonization, solvent extraction, and ion sieve adsorption. Among these, ion sieve adsorption is widely used due to its advantages such as high selective adsorption, recyclability, simple process flow, and environmental friendliness, and has shown significant industrialization potential.

[0003] Lithium-ion sieves typically exist in powder form, characterized by poor flowability and difficulty in recycling. Molding lithium-ion sieves can improve these defects; for example, they can be made into granules, films, fibers, and foams. While granular lithium-ion sieves offer improved stability, their adsorption capacity decreases significantly. Ion sieve films also face issues of membrane fouling and damage. Although fiberizing and foaming ion sieves can increase adsorption capacity, the manufacturing process is complex and lacks the necessary industrial production equipment.

[0004] Magnetizing lithium-ion sieves and utilizing magnetic separation technology to achieve efficient solid-liquid separation is a novel method for modifying ion sieves. This method eliminates the need for complex separation and recovery steps, preserving the powdered form of the ion sieve while achieving more efficient lithium-ion separation and recovery. However, adsorption losses can occur during lithium extraction using magnetic lithium-ion sieves. This is mainly due to the easy dissolution of manganese during the acidification of the lithium-ion sieve precursor with hydrochloric acid, thus limiting the industrial development of lithium-ion sieves. Summary of the Invention

[0005] This invention addresses the problems existing in the prior art by creatively proposing the use of Fe 3+ By doping and coating with ZrO2, a magnetic lithium-ion sieve is prepared. By using both metal cation doping and coating methods, the dissolution loss of manganese and iron is reduced simultaneously, achieving efficient solid-liquid separation and greatly increasing the service life of the lithium-ion sieve. Due to the acid and alkali resistance of ZrO2, this invention can be applied to the extraction of lithium from various lithium-containing solutions.

[0006] The technical solution adopted in this invention is: a Fe 3+ The preparation of ZrO2-doped magnetic lithium-ion sieve materials is characterized by the development of lithium-ion sieve materials with acid resistance, high cycleability, and easy solid-liquid separation. Fe3O4 is used to complete the Fe... 3+The doping of iron ions magnetizes the lithium-ion sieve, and the surface coating with ZrO2 results in acid and alkali resistance and solvent resistance. This invention provides a method for preparing an iron-doped ZrO2-coated magnetic lithium-ion sieve, which is specifically completed according to the following steps:

[0007] A method for preparing an iron-doped ZrO2-coated magnetic lithium-ion sieve is specifically carried out according to the following steps:

[0008] I. Preparation of FO:

[0009] Ferric chloride hexahydrate was dissolved in ethylene glycol and sonicated. Sodium acetate was then added and sonicated again to obtain a mixture. The mixture was transferred to a reaction vessel and hydrothermally reacted at 200°C for a period of time to obtain a precipitate. The precipitate was separated by magnetism, washed, and dried to obtain nano-Fe3O4, denoted as FO.

[0010] II. Preparation of LMFO:

[0011] LiOH·H2O, MnO2 and FO were ground in an agate mortar and then transferred to a corundum crucible. The corundum crucible was placed in a muffle furnace and heated to 400℃~450℃. The mixture was then calcined at 400℃~450℃ for a period of time to obtain a lithium-ion sieve precursor doped with nano Fe3O4, denoted as LMFO.

[0012] III. Preparation of ZrO2@LMFO:

[0013] LMFO and Zr(NO3)4·5H2O were added to deionized water, and then the mixture was shaken evenly in a shaker for a period of time. After drying, the dried powder was transferred to an alumina crucible, and then the alumina crucible was placed in a muffle furnace. The muffle furnace was heated to 400℃~450℃, and then calcined at 400℃~450℃ for a period of time to obtain ZrO2-coated magnetic lithium-ion sieve precursor, denoted as ZrO2@LMFO.

[0014] IV. Preparation of ZrO2@HMFO:

[0015] ZrO2@LMFO was placed in an HCl solution, then placed in a shaker and shaken evenly for acid washing. After filtration, the resulting solid was washed until neutral and dried to obtain an iron-doped ZrO2-coated magnetic lithium-ion sieve, denoted as ZrO2@HMFO.

[0016] The principle of this invention:

[0017] I. Zirconia is an inert oxide resistant to acid corrosion and does not affect the magnetism of objects, or is it Li... + and H + Excellent conductor, which is beneficial to Li + and H +The ion exchange reaction of Li-ion sieves can be further reduced by coating them with ZrO2, allowing for multiple recycling of the ion sieves and promoting the ion exchange reaction of Li-ion sieves. + and H + The improved ion exchange performance and accelerated adsorption efficiency are of great significance for its industrialization process.

[0018] II. This invention combines magnetization and coating technologies to prepare a ZrO2-coated Fe complex. 3+ Doping makes lithium ion sieves Li4Mn5O 12 It also possesses high recycling performance and magnetic properties. The recyclability of this ion sieve can be guaranteed while achieving good solid-liquid separation. This process is simple to prepare, allows for multiple cycles with stable manganese and iron dissolution, exhibits good magnetic separation performance, and is suitable for mass production, thus contributing to the industrialization of lithium extraction from salt lake brine.

[0019] The beneficial effects of the preparation method of the iron ion-doped ZrO2-coated magnetic lithium-ion sieve of the present invention are as follows:

[0020] I. Compared with other traditional materials, ion sieves have the advantages of low cost, easy manufacturing and large adsorption capacity. However, the lithium manganese spinel prepared by existing processes is in powder form. In actual production, it is impossible to separate this powder material from water. By magnetizing the lithium ion sieve, solid-liquid separation can be easily achieved, and the problem of reduced adsorption capacity caused by granulation or film formation can be avoided.

[0021] Second, magnetization requires iron doping, which leads to the dissolution of both manganese and iron during acidification. This not only reduces the cycle life of the lithium-ion sieve but also affects its magnetism. However, ZrO2 is an acid and alkali resistant material that does not affect magnetism and is also beneficial for H2O. + and Li + Because of its conductivity, coating ZrO2 can reduce the dissolution loss of manganese and iron, increase the exchange efficiency, and maintain the magnetic properties of the powder. Attached Figure Description

[0022] Figure 1 The image shows a magnetic lithium-ion sieve coated with iron-doped ZrO2 placed in a beaker, stirred, and then placed on a magnet. After five seconds, the lithium-ion sieve is attracted by the magnet. In the image, (a) shows the turbid magnetic lithium-ion sieve coated with iron-doped ZrO2 prepared in Example 4; (b) shows the magnetic lithium-ion sieve coated with iron-doped ZrO2 prepared in Example 4 that is attracted by the magnet; and (c) shows the magnetic lithium-ion sieve coated with iron-doped ZrO2 prepared in Example 3 in the beaker on the left and the magnetic lithium-ion sieve coated with iron-doped ZrO2 prepared in Example 4 in the beaker on the right.

[0023] Figure 2XRD patterns of LMO, LMFO prepared in Example 4, ZrO2@LMFO prepared in Example 4, and ZrO2@HMFO prepared in Example 4;

[0024] Figure 3 Magnetic analysis diagrams of LMO, ZrO2@LMFO prepared in Example 4, and ZrO2@HMFO prepared in Example 4;

[0025] Figure 4 Valence state analysis diagrams of LMO, LMFO prepared in Example 4, and ZrO2@LMFO prepared in Example 4 are shown. In the figure, (a) is the valence state analysis of Mn in LMO; (b) is the valence state analysis of Mn in LMFO; (c) is the valence state analysis of Mn in ZrO2@LMFO; and (d) is the valence state analysis of Fe in ZrO2@LMFO.

[0026] Figure 5 The graph shows the relationship between time and adsorption amount for ZrO2@HMFO prepared in Example 4;

[0027] Figure 6 This is a selectivity diagram for lithium-ion sieves;

[0028] Figure 7 Mn in the solution during desorption of HMO, HMFO and ZrO2@HMFO prepared in Example 4 2+ Fe 3 +、Zr 4+ Content chart. Detailed Implementation

[0029] Specific Implementation Method 1: This implementation method describes a method for preparing an iron ion-doped ZrO2-coated magnetic lithium-ion sieve, which is specifically completed according to the following steps:

[0030] I. Preparation of FO:

[0031] Ferric chloride hexahydrate was dissolved in ethylene glycol and sonicated. Sodium acetate was then added and sonicated again to obtain a mixture. The mixture was transferred to a reaction vessel and hydrothermally reacted at 200°C for a period of time to obtain a precipitate. The precipitate was separated by magnetism, washed, and dried to obtain nano-Fe3O4, denoted as FO.

[0032] II. Preparation of LMFO:

[0033] LiOH·H2O, MnO2 and FO were ground in an agate mortar and then transferred to a corundum crucible. The corundum crucible was placed in a muffle furnace and heated to 400℃~450℃. The mixture was then calcined at 400℃~450℃ for a period of time to obtain a lithium-ion sieve precursor doped with nano Fe3O4, denoted as LMFO.

[0034] III. Preparation of ZrO2@LMFO:

[0035] LMFO and Zr(NO3)4·5H2O were added to deionized water, and then the mixture was shaken evenly in a shaker for a period of time. After drying, the dried powder was transferred to an alumina crucible, and then the alumina crucible was placed in a muffle furnace. The muffle furnace was heated to 400℃~450℃, and then calcined at 400℃~450℃ for a period of time to obtain ZrO2-coated magnetic lithium-ion sieve precursor, denoted as ZrO2@LMFO.

[0036] IV. Preparation of ZrO2@HMFO:

[0037] ZrO2@LMFO was placed in an HCl solution, then placed in a shaker and shaken evenly for acid washing. After filtration, the resulting solid was washed until neutral and dried to obtain an iron-doped ZrO2-coated magnetic lithium-ion sieve, denoted as ZrO2@HMFO.

[0038] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: the mass ratio of ferric chloride hexahydrate to ethylene glycol in step one is (0.3g~2g):(30mL~100mL); the mass ratio of sodium acetate to ethylene glycol in step one is (2g~4g):(30mL~100mL). All other steps are the same as in Specific Implementation Method One.

[0039] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: the ultrasonic treatment time in step one is 30-90 minutes; the washing in step one involves washing with anhydrous ethanol 3-5 times; and the drying temperature is 60-80°C. Other steps are the same as in Specific Implementation Method One or Two.

[0040] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the hydrothermal reaction time in step one is 6 to 8 hours. The other steps are the same as in Specific Implementation Methods One to Three.

[0041] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the mass ratio of LiOH·H2O, MnO2, and FO in step two is (1-2):(2-3):(0.1-0.2). The other steps are the same as in Specific Implementation Methods One to Four.

[0042] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in the following ways: the grinding time in step two is 10 to 20 minutes; the heating rate of the muffle furnace in step two is 5°C / min to 10°C / min; and the calcination time at 400°C to 450°C in step two is 3 to 5 hours. The other steps are the same as in Specific Implementation Methods One to Five.

[0043] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One through Six in that: the mass ratio of LMFO to Zr(NO3)4·5H2O in step three is 1:(0.1-0.2); the mass ratio of LMFO to deionized water in step three is 1g:100mL; and the shaking time in step three is 20-40 minutes. Other steps are the same as in Specific Implementation Methods One through Six.

[0044] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in the following ways: the heating rate of the muffle furnace in step three is 5℃ / min to 10℃ / min; the calcination time at 400℃ to 450℃ in step three is 2h to 3h; and the drying temperature in step three is 80℃ to 100℃. Other steps are the same as in Specific Implementation Methods One to Seven.

[0045] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: the concentration of the HCl solution in step four is 0.5 mol / L; the mass ratio of ZrO2@LMFO to the volume ratio of the HCl solution in step four is 1 g:(80 mL to 120 mL). The other steps are the same as in Specific Implementation Methods One to Eight.

[0046] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that: the shaking and pickling time in step four is 5 to 8 hours; in step four, deionized water is used to wash the obtained solid material until it is neutral, and then it is dried at 80°C. Other steps are the same as in Specific Implementation Methods One to Nine.

[0047] The beneficial effects of the present invention are verified using the following embodiments:

[0048] In Examples 1-5, the doping amount of Fe3O4 in the second step was varied to determine the optimal effect.

[0049] Example 1: A method for preparing an iron-doped ZrO2-coated magnetic lithium-ion sieve, specifically completed according to the following steps:

[0050] I. Preparation of FO:

[0051] 1.08 g of ferric chloride hexahydrate (FeCl3·6H2O) was dissolved in 40 mL of ethylene glycol and sonicated for 1 h. Then, 3 g of sodium acetate (CH3COONa) was added and sonicated for 1 h to obtain a mixture. The mixture was transferred to a reaction vessel and hydrothermally reacted at 200 °C for 8 h to obtain a precipitate. The precipitate was separated by magnetism and then washed three times with deionized water and anhydrous ethanol, respectively. The product was then removed by magnetism and dried at 60 °C to obtain nano-Fe3O4, denoted as FO.

[0052] II. Preparation of LMFO:

[0053] 1.1172g LiOH·H2O, 2.871g MnO2 and 0.0309g FO were ground in an agate mortar for 10 minutes, then transferred to a corundum crucible. The corundum crucible was placed in a muffle furnace, the muffle furnace was heated to 450℃, and then calcined at 450℃ for 4 hours to obtain a lithium-ion sieve precursor doped with nano Fe3O4, denoted as LMFO.

[0054] The heating rate of the muffle furnace described in step two is 5°C / min;

[0055] III. Preparation of ZrO2@LMFO:

[0056] 1 g LMFO and 0.1 g Zr(NO3)4·5H2O were added to 100 mL of deionized water, and then the mixture was shaken evenly in a shaker for 30 min. The mixture was then dried at 80 °C. The dried powder was transferred to an alumina crucible, which was then placed in a muffle furnace. The muffle furnace was heated to 450 °C and calcined at 450 °C for 2 h to obtain a ZrO2-coated magnetic lithium-ion sieve precursor, denoted as ZrO2@LMFO.

[0057] The heating rate of the muffle furnace described in step three is 5°C / min;

[0058] IV. Preparation of ZrO2@HMFO:

[0059] 1 g of ZrO2@LMFO was placed into 100 mL of 0.5 mol / L HCl solution, then placed in a shaker and shaken evenly for 8 h for acid washing. After filtration, the obtained solid material was washed with deionized water until neutral, and then dried at 80 °C to obtain iron ion doped ZrO2 coated magnetic lithium ion sieve, denoted as ZrO2@HMFO.

[0060] Example 2: The difference between this example and Example 1 is that in step two, 1.1172g LiOH·H2O, 2.8362g MnO2, and 0.0618g FO are placed in an agate mortar and ground for 10 minutes. All other steps and parameters are the same as in Example 1.

[0061] Example 3: The difference between this example and Example 1 is that in step two, 1.1172g LiOH·H2O, 2.8014g MnO2, and 0.0928g FO are ground in an agate mortar for 10 minutes. All other steps and parameters are the same as in Example 1.

[0062] Example 4: The difference between this example and Example 1 is that in step two, 1.1172g LiOH·H2O, 2.7666g MnO2, and 0.12372g FO are ground in an agate mortar for 10 minutes. All other steps and parameters are the same as in Example 1.

[0063] Example 5: The difference between this example and Example 1 is that in step two, 1.1172g LiOH·H2O, 2.7318g MnO2, and 0.1546g FO are ground in an agate mortar for 10 minutes. All other steps and parameters are the same as in Example 1.

[0064] Comparative Example 1: LMO(Li4Mn5O) 12 The preparation method of ) is specifically carried out according to the following steps:

[0065] 1.1172 g of LiOH·H2O and 2.9 g of MnO2 were ground in an agate mortar for 10 min, then transferred to a corundum crucible. The corundum crucible was placed in a muffle furnace, and the temperature of the muffle furnace was increased to 450 °C at a heating rate of 5 °C / min. The mixture was then calcined at 450 °C for 6 h to obtain LMO(Li4Mn5O) 12 ).

[0066] Comparative Example 2: HMO(H4Mn5O) 12 The preparation method of ) is specifically carried out according to the following steps:

[0067] 1.1172 g LiOH·H2O and 2.9 g MnO2 were ground in an agate mortar for 10 min, then transferred to a corundum crucible. The corundum crucible was placed in a muffle furnace, and the furnace was heated to 450 °C at a rate of 5 °C / min. The mixture was then calcined at 450 °C for 6 h. After cooling to room temperature, it was acid-washed with 100 mL of 0.5 mol / L HCl for 8 h to obtain HMO(H4Mn5O) 12 ).

[0068] Comparative Example 3: HMFO(H 1.33 Mn 1.59 Fe 0.08 O 12 The preparation method of ) is specifically carried out according to the following steps:

[0069] 1.1172 g LiOH·H₂O, 2.9 g MnO₂, and 0.12372 g FO were ground in an agate mortar for 10 min, then transferred to a corundum crucible. The corundum crucible was placed in a muffle furnace, and the furnace was heated to 450 °C at a rate of 5 °C / min. The mixture was then calcined at 450 °C for 6 h. After cooling to room temperature, it was acid-washed with 100 mL of 0.5 mol / L HCl for 8 h to obtain HMFO(H 1.33 Mn 1.59 Fe 0.08 O 12 ).

[0070] Figure 1 The image shows a magnetic lithium-ion sieve coated with iron-doped ZrO2 placed in a beaker, stirred, and then placed on a magnet. After five seconds, the lithium-ion sieve is attracted by the magnet. In the image, (a) shows the turbid magnetic lithium-ion sieve coated with iron-doped ZrO2 prepared in Example 4; (b) shows the magnetic lithium-ion sieve coated with iron-doped ZrO2 prepared in Example 4 that is attracted by the magnet; and (c) shows the magnetic lithium-ion sieve coated with iron-doped ZrO2 prepared in Example 3 in the beaker on the left and the magnetic lithium-ion sieve coated with iron-doped ZrO2 prepared in Example 4 in the beaker on the right.

[0071] from Figure 1 As can be seen from the data, the iron-doped ZrO2-coated magnetic lithium-ion sieve prepared in Example 3, with an Fe doping amount of 0.06, is slightly more turbid than the iron-doped ZrO2-coated magnetic lithium-ion sieve prepared in Example 4, with an Fe doping amount of 0.08.

[0072] Figure 2 XRD patterns of LMO, LMFO prepared in Example 4, ZrO2@LMFO prepared in Example 4, and ZrO2@HMFO prepared in Example 4;

[0073] from Figure 2 It can be seen that the modification of the lithium-ion sieve did not affect its crystal structure. ZrO2@LMFO and ZrO2@HMFO showed an additional ZrO2 peak, and LMFO, ZrO2@LMFO, and ZrO2@HMFO also showed an additional Fe3O4 peak, indicating that ZrO2 reacts with Fe... 3+ Doping.

[0074] Figure 3 Magnetic analysis diagrams of LMO, ZrO2@LMFO prepared in Example 4, and ZrO2@HMFO prepared in Example 4;

[0075] from Figure 3It can be seen that the saturation magnetization (MS) of ZrO2@HMFO is 6.86, and the saturation magnetization (MS) of ZrO2@LMFO is 4. LMO is not magnetic, while ZrO2@HMFO has good magnetic properties and can complete solid-liquid separation.

[0076] Figure 4 Valence state analysis diagrams of LMO, LMFO prepared in Example 4, and ZrO2@LMFO prepared in Example 4 are shown. In the figure, (a) is the valence state analysis of Mn in LMO; (b) is the valence state analysis of Mn in LMFO; (c) is the valence state analysis of Mn in ZrO2@LMFO; and (d) is the valence state analysis of Fe in ZrO2@LMFO.

[0077] Figure 4 The average valence state of LMO in XPS is +3.76. The average valence state of LMFO is +4, and the average valence state of ZrO2@LMFO is also +4. Doping with metal cations is beneficial to increasing the valence state of Mn. Furthermore... Figure 4 (d) In the XPS of Fe, 711.07 eV and 724.85 eV belong to the +3 valence, and 714.09 eV and 719.28 eV belong to the +2 valence.

[0078] The ZrO2@HMFO prepared in Example 4 was adsorbed in a 100 mL LiCl solution with a concentration of 200 mg / L for 1 h to 6 h. The relationship between time and adsorption amount is shown in the figure. Figure 5 As shown;

[0079] Figure 5 The graph shows the relationship between time and adsorption amount for ZrO2@HMFO prepared in Example 4;

[0080] from Figure 5 It can be seen that as time goes by, the adsorption time reaches a basic equilibrium of 35.8 mg / g after 4 hours.

[0081] Figure 6 This is a selectivity diagram for lithium-ion sieves;

[0082] The study found that the sample had good selectivity and the selectivity difference between LMFO and ZrO2@LMFO was small, but the selectivity difference between LMO and LMFO and ZrO2@LMFO was large. This indicates that the addition of Fe improved the selectivity of the ion sieve.

[0083] 10 mg HMO, 10 mg HMFO, and 10 mg ZrO2@HMFO prepared in Example 4 were respectively immersed in 100 mL of a 200 mg / L lithium chloride solution for 4 h, then removed and dried to obtain Li-loaded products. + HMO, carrying Li + HMFO and carrying Li +ZrO2@HMFO; 10 mg Li + HMO, 10mg loaded with Li + HMFO and 10mg of Li + ZrO2@HMFO was immersed in 40 mL of 0.1 mol / L hydrochloric acid for 3 h, and the Mn content in the solution was tested. 2+ Fe 3 +、Zr 4+ The concentration, see Figure 7 As shown;

[0084] Figure 7 Mn in the solution during desorption of HMO, HMFO and ZrO2@HMFO prepared in Example 4 2+ Fe 3 +、Zr 4+ Content chart.

[0085] from Figure 7 It can be seen that Fe is doped during the desorption process. 3+ Post-solution Mn 2+ The concentration decreased from 5.52 mg / L to 4.06 mg / L, and further decreased to 2.8 mg / L after coating with ZrO2. Both Fe doping and ZrO2 coating reduced the dissolution loss of Mn, and Fe... 3+ The concentration of Zr in the solution also decreased. 4+ The concentration was only 0.013 mg / L.

Claims

1. A method for preparing an iron-doped ZrO2-coated magnetic lithium-ion sieve, characterized in that... The saturation magnetization (MS) of the iron-doped ZrO2-coated magnetic lithium-ion sieve prepared by the method is 6.86 emu / g. After adsorption in a 100 mL LiCl solution (200 mg / L) for 4 hours, it reached basic equilibrium with an adsorption capacity of 35.8 mg / g. Further immersion in 40 mL of 0.1 mol / L hydrochloric acid for 3 hours resulted in a concentration of Mn... 2+ Fe 3 +、Zr 4+ The concentrations were only 2.8 mg / L, 0.066 mg / L, and 0.013 mg / L, respectively; The preparation method is specifically carried out according to the following steps: I. Preparation of FO: 1.08 g of ferric chloride hexahydrate was dissolved in 40 mL of ethylene glycol and sonicated for 1 h. Then, 3 g of sodium acetate was added and sonicated for 1 h to obtain a mixture. The mixture was transferred to a reaction vessel and hydrothermally reacted at 200 °C for 8 h to obtain a precipitate. The precipitate was separated by magnetism and then washed three times with deionized water and anhydrous ethanol, respectively. The product was then removed by magnetism and dried at 60 °C to obtain nano-Fe3O4, denoted as FO. II. Preparation of LMFO: 1.1172g LiOH·H2O, 2.7666g MnO2 and 0.12372g FO were ground in an agate mortar for 10 minutes, then transferred to a corundum crucible. The corundum crucible was placed in a muffle furnace, the muffle furnace was heated to 450℃, and then calcined at 450℃ for 4 hours to obtain a lithium-ion sieve precursor doped with nano Fe3O4, denoted as LMFO. The heating rate of the muffle furnace described in step two is 5°C / min; III. Preparation of ZrO2@LMFO: 1 g LMFO and 0.1 g Zr(NO3)4·5H2O were added to 100 mL of deionized water, and then the mixture was shaken evenly in a shaker for 30 min. The mixture was then dried at 80 °C. The dried powder was transferred to an alumina crucible, which was then placed in a muffle furnace. The muffle furnace was heated to 450 °C and calcined at 450 °C for 2 h to obtain a ZrO2-coated magnetic lithium-ion sieve precursor, denoted as ZrO2@LMFO. The heating rate of the muffle furnace described in step three is 5°C / min; IV. Preparation of ZrO2@HMFO: 1 g of ZrO2@LMFO was placed into 100 mL of 0.5 mol / L HCl solution, then placed in a shaker and shaken evenly for 8 h for acid washing. After filtration, the obtained solid material was washed with deionized water until neutral, and then dried at 80 °C to obtain iron ion doped ZrO2 coated magnetic lithium ion sieve.

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