Manganese-based lithium ion sieve composite material, preparation method, regeneration method and use thereof

Abstract

The application provides a manganese-based lithium ion sieve composite material, a preparation method, a regeneration method and an application, and the manganese-based lithium ion sieve composite material comprises a core and a coating layer, the core comprises a manganese-based lithium ion sieve, and the coating layer comprises a hydrotalcite, and interlayer guest anions of the hydrotalcite comprise molybdate. The manganese-based lithium ion sieve is coated by the hydrotalcite with molybdate as the guest anion, in the process of lithium ion sieve delithiation, molybdate is used to intercept dissolved Mn 2+ , insoluble manganese molybdate is formed and stored in the hydrotalcite, and the influence of manganese dissolution can be avoided. The obtained manganese-based lithium ion sieve composite material can be regenerated and prepared into a doped lithium ion sieve after a plurality of lithium extraction and deintercalation cycles and is applied again.

Description

Technical Field

[0001] This invention belongs to the field of lithium extraction technology, and relates to a manganese-based lithium ion sieve composite material, its preparation method, regeneration method and application. Background Technology

[0002] With the rapid and large-scale development of lithium-ion energy storage, such as power batteries, the demand for lithium resources is increasing. Traditional lithium extraction technologies from various lithium-containing ores have drawbacks such as complex processes, high energy consumption, significant environmental impact, low resource utilization, and high costs, and are easily limited by the availability of ore reserves.

[0003] Liquid lithium resources refer to salt lake brines or seawater with high lithium content. Among them, salt lake brine lithium resources account for about 90% of the world's proven lithium resources. However, due to the characteristics of liquid lithium resources, such as low lithium ion concentration, high magnesium-to-lithium ratio (in salt lake brines), complex composition, and many associated elements, coupled with the lack of mature separation and extraction technology, liquid lithium resources cannot be developed and utilized on an industrial scale for the time being.

[0004] To separate and extract lithium ions from liquid lithium ore, researchers have developed various lithium extraction methods, such as calcination impregnation, solar evaporation, co-precipitation, and solvent extraction. However, these methods all have certain technical limitations. Adsorption, on the other hand, is a more ideal lithium extraction technology, better suited for the large-scale separation and enrichment of lithium ions in large volumes of liquids. It features low energy consumption, environmental friendliness, high lithium selectivity, and ease of operation.

[0005] High-performance lithium-ion sieves are key to the adsorption method. A lithium-ion sieve is a material that can selectively identify and adsorb lithium ions. Based on the mechanism of ion exchange, after the target lithium ions are extracted (lithium-poor state), they have the ability to reintroduce the target lithium ions and react to form a composite material (lithium-rich state). Therefore, they can be used in electrochemical lithium extraction technology. Examples include titanate lithium-ion sieves (such as lithium titanate), phosphate lithium-ion sieves (such as lithium iron phosphate), and silicate lithium-ion sieves (such as lithium silicate). However, none of the above types of lithium-ion sieves can simultaneously possess high lithium extraction capacity and long-term stability.

[0006] Spinel-type manganese oxide is a lithium-ion sieve material that has recently attracted much attention. Its stable spinel structure and special three-dimensional tunnel structure give it advantages such as high adsorption capacity, good selectivity, good recyclability and low raw material cost, making it an ideal electrochemical adsorption material.

[0007] Manganese-based lithium-ion sieves, such as spinel-type manganese oxide (LMO), are a type of lithium-ion sieve material that has recently attracted much attention. Due to their stable spinel structure and unique three-dimensional tunnel structure, they possess advantages such as high adsorption capacity, good selectivity, and good recyclability. Furthermore, their widely available raw materials offer cost advantages, making them the most promising lithium-ion adsorption materials. However, the Mn content in LMO... 3+ Due to its unique 3d orbital electronic configuration (t2g3-eg1), it can cause the Jahn-Teller effect during use, leading to severe distortion of the octahedral MnO6 structure, which in turn results in manganese capacity loss and easily causes lithium-ion sieves to precipitate in Li. + The stability of the extraction / intercalation process is affected, leading to a decrease in lithium extraction efficiency. More seriously, the large amount of manganese dissolved in water can cause serious water pollution problems during industrial production, increasing the processing steps and costs.

[0008] Therefore, it is necessary to improve manganese-based lithium ion sieves to solve the problem of manganese loss, which is of great significance for developing efficient, environmentally friendly and economical liquid lithium ore extraction technology. Summary of the Invention

[0009] In view of the problems existing in the prior art, the purpose of this invention is to provide a manganese-based lithium-ion sieve composite material, its preparation method, regeneration method, and applications. The manganese-based lithium-ion sieve composite material includes a core and a coating layer. The core includes a manganese-based lithium-ion sieve, and the coating layer includes hydrotalcite. The interlayer guest anion of the hydrotalcite includes molybdic acid. By coating the manganese-based lithium-ion sieve with hydrotalcite whose guest anion is molybdic acid, the molybdic acid is used to retain the dissolved Mn during the lithium-ion sieve delithiation process. 2+ The process forms insoluble manganese molybdate, which is stored in the hydrotalcite, thus avoiding the effects of manganese leaching. The resulting manganese-based lithium-ion sieve composite material can be regenerated into a doped lithium-ion sieve for reuse after multiple lithium extraction and deintercalation cycles.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a manganese-based lithium ion sieve composite material, comprising a core and a coating layer, wherein the core comprises a manganese-based lithium ion sieve, the coating layer comprises hydrotalcite, and the interlayer guest anion of the hydrotalcite comprises molybdic acid.

[0012] This invention provides a renewable manganese-based lithium-ion sieve composite material, comprising a manganese-based lithium-ion sieve core and a hydrotalcite coating layer covering the core. The guest anion of the hydrotalcite is molybdic acid, which inhibits the dissolution of Mn during the lithium-ion sieve delithiation process. 2+ The process of trapping and forming insoluble manganese molybdate adhering to the surface of the hydrotalcite can, on the one hand, prevent Mn from being trapped. 2+Inflow into water bodies increases post-treatment costs or pollutes the environment; on the other hand, the intercepted Mn... 2+ As a source of manganese during regeneration, the recycling effect is achieved. That is, when the manganese-based lithium ion sieve composite material after multiple cycles is used as raw material, not only can manganese elements be recovered, but also due to the residual metal elements of hydrotalcite in the coating layer, a doped lithium ion sieve material will be obtained in the end, and its performance will be further improved.

[0013] Specifically, hydrotalcite, or layered metal oxides (LDHs), is composed of positively charged host layers (hydroxides of two metals) and interlayer guest anions, with the general formula [M 2+ 1-x M 3+ x (OH)2]A n- x / n M 2+ and M 3+ Corresponding to divalent and trivalent metal cations, while the common guest anion A n- This includes nitrate ions, phosphate ions, carbonate ions, chloride ions, and hydroxyl ions. Based on manganese-based lithium ion sieves, such as LMO and Mn... 3+ During delithiation in dilute acid, a disproportionation reaction occurs to generate Mn. 4+ and Mn 2+ , among which, Mn 4+ Mn remains trapped in the ion sieve. 2+ Dissolution: This invention uses molybdate as the guest anion between layers, allowing it to react with Mn. 2+ It can rapidly combine to form manganese molybdate, which is insoluble in dilute acids, and precipitate and adhere to the outer surface of hydrotalcite. Simultaneously, anions in the aqueous solution, such as Cl... - It will be displaced into the interlayer, allowing the hydrotalcite to maintain its electrical neutrality; in addition, metal ions M 2+ (such as Ni) 2+ or Zn 2+ M 3+ (e.g. Fe) 3+ Or Al 3+ The manganese-based ion sieve composite material and molybdenum will partially replace the Mn element as dopants during the regeneration process, thereby improving the lithium extraction performance of the regenerated lithium ion sieve.

[0014] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following technical solutions.

[0015] As a preferred embodiment of the present invention, the manganese-based lithium-ion sieve comprises lithium manganese spinel in a lithium-poor state, wherein the lithium manganese spinel comprises LiMn2O4 and Li1.5 Mn2O4, Li 1.33 Mn 1.67 O4 or Li 1.6 Mn 1.6 At least one of O4, for example, typical but non-limiting combinations include LiMn2O4 and Li 1.5 Combinations of Mn2O4, LiMn2O4 and Li 1.33 Mn 1.67 Combinations of O4, LiMn2O4 and Li 1.6 Mn 1.6 O4 combination, Li 1.5 Mn2O4 and Li 1.33 Mn 1.67 O4 combination, Li 1.6 Mn 1.6 O4 and Li 1.5 Combinations of Mn2O4 or Li 1.33 Mn 1.67 O4 and Li 1.6 Mn 1.6 The combination of O4.

[0016] Preferably, the average particle size of the kernel is 2 to 20 μm, such as 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm or 20 μm, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0017] In this invention, the average particle size of the core can be controlled by controlling the average particle size of the manganese-based lithium ion sieve precursor, and the difference between the two is not significant.

[0018] Preferably, the mass of the coating layer accounts for 0.5% to 3% of the mass of the core, such as 0.5%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, or 3%, but is not limited to the listed values; other unlisted values ​​within the above range are also applicable.

[0019] It should be noted that in manganese-based lithium-ion sieve composite materials, the spinel lithium manganese oxide serving as the core of the manganese-based lithium-ion sieve specifically refers to the lithium-depleted spinel lithium manganese oxide after delithiation. Only in the lithium-depleted state can it function as a "lithium extraction" material, performing the functions of lithium adsorption and extraction. After adsorption is complete, it transforms into lithium-rich spinel lithium manganese oxide. Furthermore, considering that the actual degree of delithiation may not be complete, both lithium-depleted and lithium-rich titanium spinel lithium manganese oxide may coexist.

[0020] Secondly, the present invention provides a method for preparing the manganese-based lithium ion sieve composite material described in the first aspect, the method comprising:

[0021] Manganese-based lithium ion sieve precursor, hydrotalcite raw material and molybdate are mixed, pH is adjusted and hydrothermal reaction is carried out to form a coating;

[0022] The coating was delithiated to obtain a manganese-based lithium ion sieve composite material.

[0023] As a preferred technical solution of the present invention, the preparation method includes:

[0024] Manganese-based lithium ion sieve precursor and hydrotalcite raw material are mixed to prepare a first solution. Molybdate is prepared into a second solution with a pH of 9-10. The second solution is added dropwise to the first solution to carry out a hydrothermal reaction. After solid-liquid separation, washing and drying, the coated body is obtained.

[0025] The pH value of the second solution with a pH of 9 to 10 described in this invention can be 9, 9.2, 9.4, 9.6, 9.8 or 10, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0026] Preferably, the temperature of the hydrothermal reaction is 120–160°C, such as 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, or 160°C, and the time is 12–36 hours, such as 12 hours, 16 hours, 18 hours, 20 hours, 24 hours, 28 hours, 30 hours, 32 hours, or 36 hours, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0027] As a preferred embodiment of the present invention, the manganese-based lithium-ion sieve precursor comprises lithium-rich lithium manganese spinel, wherein the lithium manganese spinel comprises LiMn2O4 and Li 1.5 Mn2O4, Li 1.33 Mn 1.67 O4 or Li 1.6 Mn 1.6 At least one of O4.

[0028] Preferably, the hydrotalcite raw material includes metal A salt and metal B salt, wherein metal A is used to form a divalent cation and metal B is used to form a trivalent cation; the metal A salt and metal B salt are water-soluble.

[0029] Preferably, the metal A comprises Zn and / or Ni, and the metal B comprises Fe and / or Al.

[0030] Preferably, the molar ratio of the metal A salt, the metal B salt, and the molybdate is 3:1:(4-6), for example, 3:1:4, 3:1:4.2, 3:1:4.4, 3:1:4.6, 3:1:4.8, 3:1:5, 3:1:5.2, 3:1:5.4, 3:1:5.6, 3:1:5.8, or 3:1:6, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0031] Insufficient molybdate intercalation will lead to Mn 2+ Insufficient retention of molybdate means that while there is enough molybdate for intercalation, excessive molybdate will result in waste.

[0032] Preferably, the molybdate includes sodium molybdate and / or sodium molybdate.

[0033] Preferably, the mass ratio of the manganese-based lithium ion sieve precursor to the hydrotalcite raw material is 1:(0.8-1.2), such as 1:0.8, 1:0.85, 1:0.9, 1:0.95, 1:1, 1:1.05, 1:1.1, 1:1.15 or 1:2, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0034] Preferably, in the first solution, the concentration of the metal A salt is 0.01M to 0.1M, for example, 0.01M, 0.02M, 0.03M, 0.04M, 0.05M, 0.06M, 0.07M, 0.08M, 0.09M or 0.1M, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0035] As a preferred embodiment of the present invention, the delithiation treatment method includes acid treatment of the coating.

[0036] Preferably, the acid solution for acid treatment includes hydrochloric acid at a concentration of 0.1 to 0.5 mol / L, such as 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, or 0.5 mol / L, but is not limited to the listed values; other unlisted values ​​within the above range are also applicable.

[0037] Preferably, the amounts of the coated body and the acid solution are controlled according to a solid-liquid ratio (S / L) of 1g:(50-200)mL, for example, 1g:50mL, 1g:60mL, 1g:70mL, 1g:80mL, 1g:90mL, 1g:100mL, 1g:110mL, 1g:120mL, 1g:130mL, 1g:140mL, 1g:150mL, 1g:160mL, 1g:170mL, 1g:180mL, 1g:190mL, or 1g:200mL, etc., but are not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0038] Preferably, the acid treatment process includes: mixing the coating with an acid solution, ultrasonically degassing, oscillating, separating the solid and liquid, ultrasonically washing, and drying to obtain a manganese-based lithium ion sieve composite material.

[0039] Thirdly, the present invention provides a method for regenerating the manganese-based lithium ion sieve composite material described in the first aspect, the regeneration method comprising:

[0040] The delithiated manganese-based lithium ion sieve composite material is subjected to a first calcination, then mixed and ground with lithium salt, and subjected to a second calcination to obtain a doped lithium ion sieve precursor.

[0041] The doped lithium-ion sieve precursor obtained by the regeneration method of this invention can be delithiated to obtain a doped lithium-ion sieve for direct application. When the core of the manganese-based lithium-ion sieve composite material is lithium manganese oxide spinel, the doped lithium-ion sieve precursor obtained by the regeneration method can still maintain the electrical properties of the lithium manganese oxide spinel type, and its performance is improved compared to the undoped lithium manganese oxide spinel type lithium-ion sieve. Furthermore, the obtained doped lithium-ion sieve precursor can be applied to the preparation method described in the second aspect of this invention, and a layer of hydrotalcite can be recoated on the outside of the doped lithium-ion sieve core to obtain a doped manganese-based lithium-ion sieve composite material, realizing the directional recycling and utilization of manganese.

[0042] In the regeneration method described in this invention, the first calcination mainly burns the hydrotalcite into metal oxides. For example, if the hydrotalcite constituting the coating layer contains Zn and Al elements, the first calcination will cause the retained Mn to be released. 2+ When it transforms into MnO2, it also generates zinc oxide, aluminum oxide, and molybdenum oxide. Further calcination with lithium salt allows the lithium salt to act as a template agent, transforming the metal elements of the various metal oxides generated in the first calcination into doped lithium manganese oxide.

[0043] Preferably, the lithium salt comprises lithium hydroxide monohydrate.

[0044] Preferably, the amount of lithium salt and the delithiated manganese lithium ion sieve composite material is controlled according to a Li:Mn molar ratio of (1.1 to 1.2):1, for example, 1.1:1, 1.1.02:1, 1.1.04:1, 1.1.06:1, 1.1.08:1 or 1.2:1, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0045] Preferably, the temperature of the first calcination is 500-700℃, such as 500℃, 520℃, 540℃, 560℃, 580℃, 600℃, 620℃, 640℃, 660℃, 680℃ or 700℃, and the time is 2-6h, such as 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0046] Preferably, the second calcination is carried out in a high-pressure autoclave.

[0047] Preferably, the second calcination includes first treating at a first temperature, and then raising the temperature to a second temperature for further treatment.

[0048] Preferably, the first temperature is 100-140℃, such as 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃ or 140℃, and the treatment time at the first temperature is 20-30h, such as 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h or 30h, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0049] Preferably, the second temperature is 400-500℃, such as 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃, or 500℃, and the treatment time at the second temperature is 2-6 hours, such as 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0050] Fourthly, the present invention provides a doped lithium-ion sieve, which is obtained using the doped lithium-ion sieve precursor described in the third aspect.

[0051] Fifthly, the present invention provides a lithium extraction and deintercalation electrode, wherein the lithium extraction and deintercalation electrode contains the manganese-based lithium ion sieve composite material described in the first aspect, or contains the manganese-based lithium ion sieve composite material obtained by the preparation method described in the second aspect, or contains the doped lithium ion sieve described in the fourth aspect.

[0052] In a sixth aspect, the present invention provides a lithium extraction apparatus comprising the lithium extraction / deintercalation electrode described in the fifth aspect.

[0053] Compared with existing technical solutions, the present invention has at least the following beneficial effects:

[0054] This invention utilizes hydrotalcite, with molybdate as the guest anion, to coat a manganese-based lithium-ion sieve, thereby enabling the control of dissolved Mn during the lithium-ion sieve delithiation process. 2+ The process involves trapping insoluble manganese molybdate, which adheres to the surface of the hydrotalcite, thus preventing Mn from being released. 2+ Inflow into water bodies increases post-treatment costs or pollutes the environment; the manganese-based lithium ion screen composite material can be recycled as raw material after multiple cycles, effectively realizing the recovery and utilization of manganese elements, and due to the metal elements in the coating layer, doped lithium ion screen materials can be obtained.

[0055] The doped lithium-ion sieve precursor obtained by the regeneration method of the present invention can be delithiated to obtain a doped lithium-ion sieve for direct application. Alternatively, the obtained doped lithium-ion sieve precursor can be recoated with a layer of hydrotalcite and delithiated to obtain a doped manganese-based lithium-ion sieve composite material, realizing the directional recycling of manganese. Attached Figure Description

[0056] Figure 1 It is the coating obtained in Example 1-1 LMO@ZnAl-MoO4 XRD pattern;

[0057] Figure 2 This is the XRD pattern of the LMO@NiFe-MoO4 coating obtained in Example 2-1;

[0058] Figure 3 Here is a SEM image of the manganese-based lithium ion sieve composite material HMO@ZnAl-MoO4 obtained in Example 1-1;

[0059] Figure 4 It is pure phase ZnAl-MoO4 without Mn adsorption before lithium extraction. 2+ SEM and TEM images at the time;

[0060] Figure 5 It is pure ZnAl-MoO4 that has adsorbed Mn after lithium extraction. 2+ SEM and TEM images at the time;

[0061] Figure 6 It is pure phase ZnAl-MoO4 without Mn adsorption before lithium extraction. 2+ And Mn adsorbed after lithium extraction 2+ XRD pattern at time;

[0062] Figure 7 The XRD patterns are of the doped lithium-ion sieve precursor LMO-x obtained in Examples 1-2;

[0063] Figure 8 These are XPS images of the LMO@ZnAl-MoO4 coating obtained in Example 1-1 and the LMO-x doped lithium-ion sieve precursor obtained in Example 1-2. Detailed Implementation

[0064] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0065] Those skilled in the art will understand that the embodiments described are merely illustrative of the invention and should not be construed as limiting the invention.

[0066] Example 1-1

[0067] This embodiment provides a manganese-based lithium ion sieve composite material, the preparation method of which includes:

[0068] The manganese-based lithium-ion sieve precursor Li with an average particle size of 2.8 μm was used. 1.6 Mn 1.6 O4 was dispersed in water, and zinc nitrate and aluminum nitrate were added and stirred to dissolve, controlling the Li... 1.6 Mn 1.6 The mass ratio of O4 to the total mass of zinc nitrate and aluminum nitrate is 1:1, and the concentration of zinc nitrate is 0.08M, yielding the first solution. Sodium molybdate is dissolved in water, and the concentration of sodium molybdate is controlled at 0.15M. 0.1M NaOH solution is added to adjust the pH to 10±0.5, and the solution is stirred to dissolve, yielding the second solution. The molar ratio of zinc nitrate, aluminum nitrate, and sodium molybdate is controlled at 3:1:6. The first solution is heated to 60℃, and the second solution is slowly added dropwise under vigorous stirring for 1 hour. Then, 0.1M NaOH solution is added to adjust the pH of the mixture to 9.5±0.5. The reactants are transferred to a reaction vessel and subjected to hydrothermal reaction at 120℃ for 24 hours to obtain a suspension. The suspension is centrifuged, and the solid is washed three times with deionized water and dried at 80℃ for 12 hours to obtain the coated body, denoted as LMO@ZnAl-MoO4.

[0069] Calculation product LMO@ZnAl-MoO4 quality and Li 1.6 Mn 1.6 O4 The proportion of feed amount is obtained ZnAl-MoO4 coating Layer mass accounts for kernel Li1.6 Mn 1.6 2.72% of the mass of O4.

[0070] LMO@ZnAl-MoO4 was added to a 0.2 mol / L hydrochloric acid solution, and the solid-liquid ratio S / L was controlled at 1 g:100 mL. After ultrasonic degassing, the mixture was shaken in a shaking box at room temperature and acid-washed for 24 h to fully remove lithium ions from the precursor. The product was then ultrasonically washed with deionized water and dried to obtain a manganese-based lithium ion sieve composite material, denoted as HMO@ZnAl-MoO4.

[0071] Examples 1-2

[0072] This embodiment provides a regeneration method for manganese-based lithium-ion sieve composite materials. The regeneration method uses the HMO@ZnAl-MoO4 prepared in Example 1-1 for lithium extraction experiments. After 50 cycles, the delithiated (lithium-poor) manganese-based lithium-ion sieve composite material is used as raw material. The Mn content in the dried raw material is determined by EDS, and the regeneration method is then performed. The regeneration method includes:

[0073] The lithium-poor manganese-based lithium-ion sieve composite material was calcined at 600℃ for 4 hours, then mixed with lithium hydroxide monohydrate. The feed amount was controlled according to the molar ratio of Li:Mn of 1.1:1. The mixture was ground until there was no obvious particle texture. The mixture was transferred to an autoclave and heated at 120℃ for 24 hours, and then further heated to 500℃ for 4 hours to obtain the doped lithium-ion sieve precursor, denoted as LMO-x.

[0074] Replacing Li in Example 1-1 with LMO-x 1.6 Mn 1.6 O4 was coated with hydrotalcite to obtain a coated body, which was then acid-treated to obtain a regenerated doped lithium-ion sieve, denoted as HMO-x.

[0075] Example 2-1

[0076] This embodiment provides a manganese-based lithium ion sieve composite material, the preparation method of which includes:

[0077] The manganese-based lithium-ion sieve precursor Li with an average particle size of 18.4 μm was used. 1.6 Mn 1.6 O4 is dispersed in water, nickel nitrate and ferric nitrate are added and stirred until dissolved, and the Li content is controlled. 1.6 Mn 1.6The mass ratio of O4 to the total mass of nickel nitrate and ferric nitrate is 1:1, and the concentration of nickel nitrate is 0.02M, yielding the first solution. Ammonium molybdate is dissolved in water, and the concentration of ammonium molybdate is controlled at 1.2M. 0.1M NaOH solution is added to adjust the pH to 9±0.5, and the solution is stirred to dissolve, yielding the second solution. The molar ratio of nickel nitrate, ferric nitrate, and ammonium molybdate is controlled at 3:1:4. The first solution is heated to 60℃, and the second solution is slowly added dropwise under vigorous stirring for 1 hour. Then, 0.15M NaOH solution is added to adjust the pH of the mixture to 9±0.5. The reactants are transferred to a reaction vessel and subjected to hydrothermal reaction at 160℃ for 24 hours to obtain a suspension. The suspension is centrifuged, and the solid is washed three times with deionized water and dried at 80℃ for 12 hours to obtain the coated body, denoted as LMO@NiFe-MoO4.

[0078] Calculate the mass of the product LMO@NiFe-MoO4 and Li 1.6 Mn 1.6 The ratio of O4 feed amount is used to obtain NiFe-MoO4 coating. Layer quality occupy kernel Li 1.6 Mn 1.6 1.15% of the mass of O4.

[0079] LMO@NiFe-MoO4 was added to a 0.2 mol / L hydrochloric acid solution, and the solid-liquid ratio S / L was controlled at 1 g:100 mL. After ultrasonic degassing, the mixture was shaken in a shaker at room temperature and acid-washed for 24 h to fully remove lithium ions from the precursor. The product was then ultrasonically washed with deionized water and dried to obtain a manganese-based lithium ion sieve composite material, denoted as HMO@NiFe-MoO4.

[0080] Example 2-2

[0081] This embodiment provides a regeneration method for manganese-based lithium-ion sieve composite materials. The regeneration method uses the HMO@NiFe-MoO4 prepared in Example 2-1 for lithium extraction experiments. After 50 cycles, the delithiated (lithium-poor) manganese-based lithium-ion sieve composite material is used as raw material. The Mn content in the dried raw material is determined by EDS, and the regeneration method is then performed. The regeneration method includes:

[0082] The lithium-poor manganese-based lithium-ion sieve composite material was calcined at 600℃ for 4 hours, then mixed with lithium hydroxide monohydrate. The feed amount was controlled according to the molar ratio of Li:Mn of 1.1:1. The mixture was ground until there was no obvious particle texture. The mixture was transferred to an autoclave and heated at 120℃ for 24 hours, and then further heated to 500℃ for 4 hours to obtain the doped lithium-ion sieve precursor, denoted as LMO-x.

[0083] Replacing Li in Example 2-1 with LMO-x 1.6 Mn 1.6O4 was coated with hydrotalcite to obtain a coated body, which was then acid-treated to obtain a regenerated doped lithium-ion sieve, denoted as HMO-x.

[0084] Example 3-1

[0085] This embodiment provides a manganese-based lithium ion sieve composite material. The preparation method adjusts the amount of sodium molybdate and changes the molar ratio of zinc nitrate, aluminum nitrate and sodium molybdate from 3:1:6 to 3:1:3. Except for the above, the other conditions are exactly the same as in Example 1-1.

[0086] Example 4-1

[0087] This embodiment provides a manganese-based lithium ion sieve composite material. The preparation method adjusts the amount of sodium molybdate and changes the molar ratio of zinc nitrate, aluminum nitrate and sodium molybdate from 3:1:6 to 3:1:4. Except for the above, the other conditions are exactly the same as in Example 1-1.

[0088] Example 5-1

[0089] This embodiment provides a manganese-based lithium ion sieve composite material. The preparation method adjusts the amount of sodium molybdate and changes the molar ratio of zinc nitrate, aluminum nitrate and sodium molybdate from 3:1:6 to 3:1:7. Except for the above, the other conditions are exactly the same as in Example 1-1.

[0090] Comparative Example 1-1

[0091] This comparative example provides a method for preparing a manganese-based lithium ion sieve. The preparation method does not use sodium molybdate. A 0.1M NaOH solution is used as the second solution. The resulting coating is denoted as LMO@ZnAl-NO3, and the resulting manganese-based lithium ion sieve is denoted as HMO@ZnAl-NO3. Except for the above, the other conditions are exactly the same as in Examples 1-1.

[0092] Comparative Examples 1-2

[0093] This comparative example provides a method for regenerating a manganese-based lithium ion sieve. The regeneration method replaces the HMO@ZnAl-MoO4 in Example 1-1 with HMO@ZnAl-NO3 in Comparative Example 1-1. Except for the above, the other conditions are exactly the same as in Example 1-2.

[0094] Control group 1-1

[0095] This comparative example uses Li from Example 1-1 1.6 Mn 1.6 O4 was delithiated and then used as a lithium-ion sieve for subsequent testing.

[0096] Characterization and testing:

[0097] (1) The crystal phase and crystal structure of the material were studied using an X-ray powder diffractometer (XRD, Rigaku D / max-2600PC, Japan). During the test, Cu Kα rays were used with a wavelength λ of 0.154056 nm, a voltage of 40 kV, a current of 40 mA, and a scanning range of 2θ of 10 to 80°. The XRD test results were analyzed using Jade 6 software.

[0098] (2) The microstructure of the sample was analyzed using a JSM-IT300LV SEM.

[0099] (3) The samples were tested using a Talos F200S G2 transmission electron microscope.

[0100] (4) The composition and valence state of the material surface were determined using an ESCALAB 250Xi X-ray photoelectron spectrometer.

[0101] Figure 1 and Figure 2 The figures show the XRD patterns of the coatings (i.e., lithium-rich manganese-based lithium-ion sieve composite materials) obtained in Examples 1-1 and 2-1, respectively. As can be seen from the figures, Example 1-1 has a structure conforming to zinc-aluminum hydrotalcite material (JCPDS No. 38-0486) and spinel L... 1.6 Mn 1.6 The presence of the correct spectral position in the structure diagram (PDF NO. 52.1841) of the O4 material, along with the low number of impurity peaks, indicates the successful synthesis of the Zn-Al-MoO4 layered double hydroxide coating. Furthermore, the diffraction peak at a 2θ angle of 23.39° corresponds to the (006) crystal plane of zinc-aluminum layered double hydroxide, and compared to Zn-Al-LDHs, the peak shifts to a smaller angle region, which confirms the presence of MoO4. 2- Anions successfully intercalated into the interlayer, increasing the interlayer spacing of Zn-Al-LDHs; Example 2 also yielded consistent results.

[0102] Figure 3 The image shows a SEM image of the manganese-based lithium ion sieve composite material HMO@ZnAl-MoO4 obtained in Example 1-1. It can be seen that the hydrotalcite grown on the surface of the lithium ion sieve has a plate-like crystal structure.

[0103] (5) To study the effect of hydrotalcite in the coating layer on Mn 2+ The adsorption mechanism was investigated through the following simulation experiment:

[0104] ① Preparation of pure phase ZnAl-MoO4: The preparation method is the same as in Example 1-1, except that the manganese-based lithium ion sieve precursor L is not added. 1.6 Mn 1.6 O4 and without delithiation treatment (acid treatment);

[0105] ②ZnAl-MoO4 was ultrasonically dispersed in Mn 2+ The solution (0.01g manganese chloride dissolved in 100mL 0.2M HCl solution) was then allowed to stand at room temperature for 24h, centrifuged, washed with deionized water until the washing solution was neutral, and dried at 80℃ to constant weight to obtain the sample to be tested.

[0106] ③ Perform SEM, TEM, and XRD tests on the sample to be tested. After adsorption for a certain period of time, test the ion concentration of the solution in step ②. Use ICP-OES to measure the concentration of metal cations in the solution and use the ion-selective electrode method to measure the concentration of chloride ions in the solution. The results are listed in Table 1.

[0107] Table 1

[0108]

[0109] Figure 4 It is pure phase ZnAl-MoO4 without Mn adsorption before lithium extraction. 2+ SEM at time Figure 4 (a) and TEM image ( Figure 4 (b)); Figure 5 It is pure ZnAl-MoO4 that has adsorbed Mn after lithium extraction. 2+ SEM at time Figure 5 (a) and TEM image ( Figure 5 (b)); As can be seen from the figure, the adsorption of Mn 2+ Subsequently, obvious manganese molybdate particles were precipitated on the surface of the material; Figure 6 The obtained pure phase ZnAl-MoO4 did not adsorb Mn before lithium extraction. 2+ And Mn adsorbed after lithium extraction 2+ The XRD comparison images show that after adsorption, the XRD patterns of the sample show diffraction peaks of MnMoO4·H2O crystals. Additionally, the diffraction peaks corresponding to the (006) crystal plane of Zn-Al-MoO4 have two peaks, one corresponding to MoO4. 2- The intercalation peak position is the same as that of the material before adsorption, at 23.28°, and the other peak position is 23.39°, consistent with that in JCPDS No. 38-0486, indicating that the corresponding intercalated guest ion radius is greater than that of MoO4. 2- Smaller, and in the liquid environment of this invention (hydrochloric acid solution of manganese chloride), based on the data patterns in Table 1, the corresponding intercalation guest should be Cl. - Ions. In summary, Zn-Al-MoO4 is effective against Mn. 2+ The adsorption mechanism is ion exchange, i.e., Cl... - Replaced with MoO4 2- And MoO4 2- With Mn2+ It combines to form MnMoO4, which is insoluble in dilute acid and precipitates out and adheres to the surface of hydrotalcite.

[0110] (6) Lithium-ion sieve adsorption performance (lithium extraction test):

[0111] ① Adsorption capacity: Unextracted lithium-ion sieves were immersed in a lithium-containing solution (lithium concentration 0.05 mol / L, S / L = 1 g: 1000 mL) and shaken at 100 rpm in a constant-temperature shaking oven at 25 °C for 24 h to ensure adsorption equilibrium was reached. The Li content in the solution was determined using ICP-OES. + The content of . Adsorption capacity Q e The formula for calculating (mg / g) is as follows:

[0112]

[0113] In the formula, C0 (mg / L) represents Li + The initial concentration of C; e (mg / L) is the concentration of lithium ions when adsorption equilibrium is reached; V(L) is the volume of the solution; m(g) is the mass of the lithium ion sieve.

[0114] ② Manganese loss: After lithium extraction, the lithium-rich lithium-ion sieve was acid-washed with 0.2 mol / L HCl at a solid-liquid ratio of 1:100 for 24 hours at room temperature. The supernatant was partially collected using a pipette, and the concentration of metal cations in the solution was measured using ICP-OES. Then, the manganese loss rate (DE) was calculated. Mn ).

[0115]

[0116] C1 (mg / L) is the detection concentration of manganese ions, V1 (L) is the solution volume, and m (g) is the mass of the lithium ion sieve precursor.

[0117] The results are shown in Table 2.

[0118] Table 2

[0119]

[0120] As can be seen from Table 2, the adsorption capacity of the regenerated lithium-ion sieve decreased, which is due to the reduction in LMO per unit mass.

[0121] Comparative Example 1-1 Q e Similar to the examples, the hydrotalcite does not adsorb Li, and the L in the examples is different from that in the control group 1-1. 1.6 Mn 1.6 The similarity of Qe between O4 and O4 indicates that the hydrotalcite coating did not reduce the Li insertion / extraction efficiency, and therefore did not cause a decrease in lithium extraction capacity.

[0122] Compared with Examples 1-1 and 2-1, Examples 1-2 and 2-2 show that the regenerated lithium-ion screens have lower manganese loss, indicating that heteroion doping is beneficial to reducing manganese dissolution.

[0123] Figure 7 The figures show the XRD patterns of the doped lithium-ion sieve precursor LMO-x obtained in Examples 1-2. As can be seen from the figures, the manganese-based lithium-ion sieve composite material after lithium extraction cycling, after the regeneration method described above, and the doped lithium-ion sieve precursor obtained after calcination regeneration from the lithium source, still maintain a spinel structure, conforming to PDF No. 52-1841 (Li 1.6 Mn 1.6 Structural spectrum of O4);

[0124] Figure 8 The images show XPS spectra of the LMO@ZnAl-MoO4 coating obtained in Example 1-1 and the LMO-x doped lithium-ion sieve precursor obtained in Example 1-2. The figures show that the characteristic peaks of the Mn 2p orbitals at 643.25 eV and 642.12 eV are attributed to Mn, respectively. 4+ and Mn 3+ The binding energy of Mn in the two materials was calculated based on the peak intensity information. 4+ and Mn 3+ The proportion of Mn was calculated, and the average valence of Mn was listed in Table 3. The average valence of Mn in the regenerated LMO-x was increased. The possible reason is that elements such as Mo, Al, and Zn doped LMO during the calcination process, which improved the lattice stability of LMO.

[0125] Table 3

[0126] <![CDATA[LMO@Zn-Al-MoO4 of Example 1-1]]> 32174 23264 3.58 LMO-x in Examples 1-2 30981 13712 3.69

[0127] As can be seen from the above, this invention coats a manganese-based lithium-ion sieve with a hydrotalcite containing molybdate as the guest anion, and utilizes molybdate to retain the dissolved Mn during the lithium-ion sieve delithiation process. 2+ The process involves forming insoluble manganese molybdate, which is stored in hydrotalcite, thus preventing manganese leaching. The resulting manganese-based lithium-ion sieve composite material can be regenerated into a doped lithium-ion sieve for reuse after multiple lithium extraction and deintercalation cycles, achieving targeted recycling of manganese.

[0128] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0129] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0130] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A manganese-based lithium-ion sieve composite material, characterized in that, It includes a core and a coating layer, wherein the core includes a manganese-based lithium ion sieve, the coating layer includes hydrotalcite, and the interlayer guest anion of the hydrotalcite includes molybdic acid; The manganese-based lithium-ion sieve includes lithium manganese spinel in a lithium-poor state. The manganese-based lithium-ion sieve composite material is prepared by the following preparation method, which includes: Manganese-based lithium ion sieve precursor, hydrotalcite raw material and molybdate are mixed, pH is adjusted and hydrothermal reaction is carried out to form a coating; The coating was delithiated to obtain a manganese-based lithium ion sieve composite material. The manganese-based lithium-ion sieve precursor includes lithium-rich lithium manganese spinel, and the lithium manganese spinel includes Li 1.5 Mn2O4, Li 1.33 Mn 1.67 O4 or Li 1.6 Mn 1.6 At least one of O4; The hydrotalcite raw material includes metal A salt and metal B salt, where metal A is used to form divalent cations and metal B is used to form trivalent cations; Metal A includes Zn and / or Ni, and metal B includes Fe and / or Al.

2. The manganese-based lithium-ion sieve composite material according to claim 1, characterized in that, The average particle size of the kernel is 2~20μm.

3. The manganese-based lithium-ion sieve composite material according to claim 1, characterized in that, The mass of the coating layer accounts for 0.5% to 3% of the mass of the core.

4. A method for preparing a manganese-based lithium-ion sieve composite material according to any one of claims 1-3, characterized in that, The preparation method includes: Manganese-based lithium ion sieve precursor, hydrotalcite raw material and molybdate are mixed, pH is adjusted and hydrothermal reaction is carried out to form a coating; The coating was delithiated to obtain a manganese-based lithium ion sieve composite material. The manganese-based lithium-ion sieve precursor comprises lithium-rich lithium manganese spinel, which includes Li... 1.5 Mn2O4, Li 1.33 Mn 1.67 O4 or Li 1.6 Mn 1.6 At least one of O4; The hydrotalcite raw material includes metal A salt and metal B salt, where metal A is used to form divalent cations and metal B is used to form trivalent cations; Metal A includes Zn and / or Ni, and metal B includes Fe and / or Al.

5. The method for preparing the manganese-based lithium-ion sieve composite material according to claim 4, characterized in that, The preparation method includes: Manganese-based lithium ion sieve precursor and hydrotalcite raw material are mixed to prepare a first solution. Molybdate is prepared into a second solution with a pH of 9-10. The second solution is added dropwise to the first solution to carry out a hydrothermal reaction. After solid-liquid separation, washing and drying, the coated body is obtained.

6. The method for preparing the manganese-based lithium-ion sieve composite material according to claim 4, characterized in that, The hydrothermal reaction is carried out at a temperature of 120~160℃ for a duration of 12~36h.

7. The method for preparing the manganese-based lithium-ion sieve composite material according to claim 4, characterized in that, The molar ratio of the metal A salt, the metal B salt, and the molybdate is 3:1:(4~6).

8. The method for preparing the manganese-based lithium-ion sieve composite material according to claim 4, characterized in that, The molybdate includes sodium molybdate or ammonium molybdate.

9. The preparation method of the manganese-based lithium ion sieve composite material according to claim 4, characterized in that, The delithiation process includes acid treatment of the coating.

10. The method for preparing the manganese-based lithium-ion sieve composite material according to claim 9, characterized in that, The acid solution used for acid treatment includes 0.1~0.5 mol / L hydrochloric acid.

11. The method for preparing the manganese-based lithium-ion sieve composite material according to claim 10, characterized in that, The amounts of the coating body and the acid solution are controlled according to a solid-liquid ratio of 1g:(50~200)mL.

12. The method for preparing the manganese-based lithium-ion sieve composite material according to claim 9, characterized in that, The acid treatment process includes: mixing the coating with an acid solution, ultrasonically degassing, oscillating, separating the solid and liquid, ultrasonically washing, and drying to obtain a manganese-based lithium ion sieve composite material.

13. A method for regenerating the manganese-based lithium-ion sieve composite material according to any one of claims 1-3, characterized in that, The regeneration method includes: The delithiated manganese-based lithium ion sieve composite material is subjected to a first calcination, then mixed and ground with lithium salt, and subjected to a second calcination to obtain a doped lithium ion sieve precursor.

14. The regeneration method according to claim 13, characterized in that, The amount of lithium salt and the delithiated manganese-based lithium ion sieve composite material is controlled according to a Li:Mn molar ratio of (1.1~1.2):

1.

15. The regeneration method according to claim 13, characterized in that, The first calcination temperature is 500~700℃, and the time is 2~6h.

16. The regeneration method according to claim 13, characterized in that, The second calcination involves first treating at a first temperature, and then raising the temperature to a second temperature for further treatment.

17. The regeneration method according to claim 16, characterized in that, The first temperature is 100~140℃, and the treatment time at the first temperature is 20~30h.

18. The regeneration method according to claim 16, characterized in that, The second temperature is 400~500℃, and the treatment time at the second temperature is 2~6h.

19. A doped lithium-ion sieve, characterized in that, The doped lithium-ion sieve is obtained using the regeneration method described in any one of claims 13-18.

20. A lithium extraction / deintercalation electrode, characterized in that, The composite material containing the manganese-based lithium ion sieve according to any one of claims 1-3, or the composite material containing the manganese-based lithium ion sieve obtained by the preparation method according to any one of claims 4-12, or the doped lithium ion sieve according to claim 19.

21. A lithium extraction device, characterized in that, It contains the lithium extraction and deintercalation electrode as described in claim 20.

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