CN116750776A - Li-A type molecular sieve for lithium electrolyte and preparation method and application thereof - Google Patents

Li-A type molecular sieve for lithium electrolyte and preparation method and application thereof Download PDF

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CN116750776A
CN116750776A CN202310543278.2A CN202310543278A CN116750776A CN 116750776 A CN116750776 A CN 116750776A CN 202310543278 A CN202310543278 A CN 202310543278A CN 116750776 A CN116750776 A CN 116750776A
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molecular sieve
lithium
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salt solution
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权藏玉
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Luoyang Xinling Weina New Material Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
    • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
    • C01B39/14—Type A
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/16—Alumino-silicates
    • B01J20/18—Synthetic zeolitic molecular sieves
    • B01J20/186—Chemical treatments in view of modifying the properties of the sieve, e.g. increasing the stability or the activity, also decreasing the activity
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention belongs to the field of molecular sieve adsorption materials, and particularly relates to a Li-A type molecular sieve for lithium electrolyte, and a preparation method and application thereof. The preparation method of the Li-A type molecular sieve for the lithium electrolyte comprises the steps of firstly preparing a 4A crystal-sphere type molecular sieve, then mixing the molecular sieve with an ammonium salt solution for cyclic exchange, and then mixing the molecular sieve with a lithium salt solution for cyclic exchange. The molecular sieve prepared by the method is a Li ion modified A-type adsorbent molecular sieve, has extremely low content of Na and K elements and moderate content of Li, can not bring in or only slightly bring in metal sodium and potassium ions in the dehydration process of the difluoro sulfonimide lithium electrolyte, can not cause harm to the electrolyte, has the static water adsorption capacity of more than 26 percent, is obviously superior to the static water adsorption capacity of the existing A-type molecular sieve, is suitable for being used as the dehydrator of the difluoro sulfonimide lithium electrolyte, and has good industrial application prospect.

Description

Li-A type molecular sieve for lithium electrolyte and preparation method and application thereof
Technical Field
The invention belongs to the field of molecular sieve adsorption materials, and particularly relates to a Li-A type molecular sieve for lithium electrolyte, and a preparation method and application thereof.
Background
The difluoro sulfonimide lithium salt is an additive which can be used for lithium ion battery electrolyte, and can reduce the high-low temperature resistance and capacity loss of a lithium battery and improve the electrochemical performance of the lithium battery when being used as the lithium battery electrolyte. Therefore, as a novel safe and efficient electrolyte, the lithium bis (fluorosulfonyl) imide electrolyte is gradually popularized and applied in rechargeable lithium batteries, and is also receiving more and more attention in the industry.
However, in the process of large-scale industrial production of lithium bis (fluorosulfonyl) imide electrolyte, in order to avoid the influence of moisture contained in liquid lithium bis (fluorosulfonyl) imide on the service performance of the electrolyte, generally lithium bis (fluorosulfonyl) imide for lithium batteries needs to be produced into solid materials first, and then organic solution is added for dissolution during the production of lithium batteries to be used for the production of lithium batteries. However, lithium bis (fluorosulfonyl imide) is an organic lithium electrolyte, and is difficult to be industrially produced into a solid, and not only is the energy consumption high, but also the production efficiency low. If the synthesized liquid difluoro sulfonimide lithium electrolyte can directly remove water through the adsorbent, the problem that the difluoro sulfonimide lithium electrolyte is dehydrated from liquid to solid and then is dissolved and diluted by adding an organic solvent can be solved, so that the production flow and the evaporation dehydration flow of the difluoro electrolyte are effectively reduced, and the energy consumption is reduced.
Therefore, the technical problem that the water content of the difluoro electrolyte exceeds the standard is required to be faced in the industry at the present stage, and the exposed bottleneck problem is also the dehydration problem of the difluoro electrolyte. At present, the efficient and economic electrolyte dehydration means commonly adopted in the industry is adsorption dehydration by using a molecular sieve. Commonly used molecular sieves include NaA-type molecular sieves, KA-type molecular sieves, caA-type molecular sieves, KNaA-type molecular sieves, and LiX-type molecular sieves. However, the common NaA type and KNaA type molecular sieves are adopted to dehydrate the lithium difluorosulfimide electrolyte, so that the dehydration effect is relatively poor, a large amount of Na and K ions can be definitely brought into the dehydration process, the more the sodium and potassium ions are in the lithium battery electrolyte, the higher the impedance of the battery is, the larger the thermal effect is during charging and discharging, the control of the temperature is affected, the lower the number of times of recycling the battery is, the usability of the electrolyte and the lithium battery is greatly affected, and the further application of the lithium battery is limited. While the LiX type molecular sieve has no large amount of Na and K ions, the aperture of the LiX type molecular sieve is larger than that of the difluoro molecular sieve, so that the absorption of the difluoro is caused while water is absorbed, the loss of the difluoro is caused, and the severe heat release of the molecular sieve is caused, so that the dehydration process cannot be normally performed.
Disclosure of Invention
In order to solve the problems, one of the purposes of the invention is to provide a preparation method of a Li-A type molecular sieve for lithium electrolyte, which has the advantages of simple operation, high efficiency, environmental protection and low cost, and the prepared molecular sieve has moderate adsorption pore diameter, can be effectively used for dehydrating liquid difluoro sulfimide lithium electrolyte, has good dehydration effect when in use, does not bring in or trace metal sodium and potassium ions, and does not cause harm to the electrolyte.
The second object of the invention is to provide a Li-A type molecular sieve for lithium electrolyte, which belongs to a cation modified A type adsorbent molecular sieve, and the adsorbent is high in water adsorption rate in the dehydration process of the difluoro sulfonimide lithium electrolyte, does not bring in or trace into metal sodium and potassium ions, and is suitable for the difluoro sulfonimide lithium electrolyte.
The invention further aims to provide an application of the Li-A type molecular sieve for lithium electrolyte.
In order to achieve the above object, the preparation method of the Li-A type molecular sieve for lithium electrolyte of the present invention adopts the following technical scheme:
a method for preparing a Li-A type molecular sieve for lithium electrolyte, comprising the following steps:
(1) Shaping 4A type molecular sieve raw powder into spherical particles with the diameter of 1.0-2.0 mm, and then drying and calcining to obtain a spherical molecular sieve; crystallizing the spherical molecular sieve in an alkali solution, and then washing the spherical molecular sieve with water to obtain a 4A crystal-transformation spherical molecular sieve;
(2) Mixing the 4A crystal-sphere molecular sieve with an ammonium salt solution, and then circularly exchanging for 6-9 times at the temperature of 60-85 ℃, and washing after exchange to obtain an ammonia A molecular sieve;
(3) Mixing the ammonia A type molecular sieve with lithium salt solution, then circularly exchanging for 2-5 times at 50-95 ℃, and drying and activating after the exchange is completed to obtain the Li-A type molecular sieve for lithium electrolyte.
When the Li-A type molecular sieve is prepared, the molecular sieve raw powder is firstly prepared into the spherical molecular sieve, and then the spherical molecular sieve is subjected to alkali crystallization and crystal transformation to obtain the 4A crystal transformation spherical molecular sieve for subsequent exchange operation, so that on one hand, solid-liquid separation after exchange is facilitated, material loss during solid-liquid separation after exchange is reduced, on the other hand, the exchange effect is improved, and the water adsorption performance of the molecular sieve is improved. Furthermore, the invention carries out ammonia exchange on the spherical molecular sieve, can effectively exchange K, na, ca and other ions in the molecular sieve by adopting ammonium, reduces the consumption of lithium salt during lithium exchange, and effectively promotes the subsequent lithium ion exchange process. In particular, the invention can comprehensively regulate and control the structure of the finally obtained Li-A type molecular sieve and the lithium content in the molecular sieve by controlling the times of ammonium salt exchange and lithium salt cycle exchange, thereby endowing the molecular sieve with more excellent water adsorption performance.
In addition, the Li-A type molecular sieve prepared by the method has moderate adsorption aperture and Li exchange capacity, and can be directly used for dehydrating the liquid difluoro-sulfonimide lithium electrolyte, so that the complicated steps that the liquid difluoro-sulfonimide lithium electrolyte is converted into solid for dehydration and then an organic solvent is added for dissolution and dilution are avoided, the production flow and the evaporation and dehydration flow of the difluoro-electrolyte are effectively reduced, and the energy consumption is reduced.
In order to ensure the molding effect of the spherical molecular sieve, preferably, in the step (1), the molding is specifically: mixing 4A type molecular sieve raw powder and clay, and then placing the mixed powder in a rotary forming machine to contact with water for rolling forming to obtain spherical particles; the drying and calcining are that spherical particles are dried at the temperature of 150-200 ℃ until the water content is less than 10%, and then calcined at the temperature of 680-900 ℃ until the water content is less than 1%; the mass ratio of the 4A type molecular sieve raw powder to the clay to the water is 100:8-12:10-15; the clay is one or two of kaolin and crucible clay.
In the step (1), the alkali solution is 60-100 g/L sodium hydroxide solution; the dosage ratio of the spherical molecular sieve to the alkali solution is 1g to (4-6) mL; the crystallization time is 3-5 h. According to the invention, in the early-stage exploration test, the spherical molecular sieve is further crystallized to prepare the 4A crystal-transformation spherical molecular sieve, and compared with the molecular sieve which is not crystallized, the strength of spherical particles can be improved, and meanwhile, the clay added during forming can be converted into the molecular sieve with an A-type structure, so that the static water adsorption capacity of the molecular sieve is obviously improved.
In the invention, when the molecular sieve is formed, a certain amount of cations are carried in the added clay, because the invention needs to carry out ammonium exchange after preparing spherical particles, thereby removing the cations carried in the clay through the ammonium exchange. Preferably, in the step (2), the ammonium salt solution is an ammonium sulfate solution or an ammonium nitrate solution; the concentration of the ammonium salt solution is 1-2 mol/L; the dosage ratio of the spherical molecular sieve to the ammonium salt solution is 1g to (3-8) mL.
Further, in the step (2), the cyclic switching is specifically: mixing spherical molecular sieve with ammonium salt solution, stirring and exchanging at 60-85 deg.c for 2-4 hr, eliminating waste exchange liquid, adding ammonium salt solution again, and repeating the above steps for 6-9 times.
Further, in the step (2), the water washing is to wash the exchanged spherical molecular sieve until the content of sulfate radical or nitrate radical is less than 200ppm.
In the step (3), the lithium salt solution is a lithium sulfate solution or a lithium nitrate solution; the concentration of the lithium salt solution is 0.2-0.5 mol/L; the dosage ratio of the ammonia A type molecular sieve to the lithium salt solution is 1g to (2-6) mL.
Further, in the step (3), the cyclic switching is specifically: mixing ammonia A type molecular sieve with lithium salt solution, stirring and exchanging for 1-3 h at 50-95 ℃, discarding the exchanged waste liquid after exchanging, adding lithium salt solution again, repeating the above operation, and the total number of cyclic exchanges is 2-5.
In the step (3), the drying is to dry the exchanged molecular sieve at 140-160 ℃ for 1-3 hours; the activation is to activate the dried molecular sieve for 1-2 hours at 500-550 ℃.
The Li-A type molecular sieve for the lithium electrolyte is prepared by adopting the preparation method. The adsorption aperture of the Li-A type molecular sieve for the lithium electrolyte is 0.2-0.6 nm.
The invention discloses an application of a Li-A type molecular sieve for lithium electrolyte, in particular to an application of the Li-A type molecular sieve as a difluoro sulfonimide lithium electrolyte water scavenger.
The Li-A type molecular sieve for the lithium electrolyte provided by the invention belongs to a Li ion modified A type adsorbent molecular sieve, the adsorption aperture and the content of modified Li element are moderate, the water adsorption capacity is obviously higher than that of the existing adsorbents of the same type, and when the molecular sieve adsorbent is used for the dehydration process of the liquid difluoro-sulfonimide lithium electrolyte, metal sodium and potassium ions are not carried in or carried in a trace amount, so that the molecular sieve adsorbent is harmless to the electrolyte and is very suitable for the dehydration application of the difluoro-sulfonimide lithium electrolyte.
Detailed Description
The invention is further described below in connection with specific examples, which are not to be construed as limiting the invention. The materials and operation techniques involved in the following examples are conventional in the art unless otherwise specified. Wherein, the 4A molecular sieve raw powder adopted in the following examples is from Sanjia Jianyu New Material Co., ltd, and the mesh number is 325 mesh. The mesh number of the clay is 200-400 mesh.
Example 1
The Li-A type molecular sieve for lithium electrolyte of the embodiment adopts a preparation method comprising the following steps:
(1) Mixing 4A type molecular sieve raw powder and clay, and then placing the mixed powder into a rotary forming machine to contact with water for rolling forming to obtain spherical particles with the diameter of 1.0-2.0 mm; then drying the spherical particles at 200 ℃ until the water content is less than 10%, and calcining at 760 ℃ for 2 hours until the water content is less than 1%, thus obtaining the spherical molecular sieve; wherein the mass ratio of the 4A molecular sieve raw powder to the clay to the water is 100:10:13; the clay is kaolin;
crystallizing the spherical molecular sieve in 80g/L sodium hydroxide solution for 4 hours according to the ratio of 1g to 5mL, and then washing to obtain the 4A crystal-transformation spherical molecular sieve;
(2) Mixing the 4A crystal-transformation spherical molecular sieve obtained in the step (1) with an ammonium salt solution, regulating the pH value of the exchange liquid to 9 by ammonia water, stirring and exchanging for 2 hours at the temperature of 65 ℃, discarding the exchange waste liquid after exchanging, adding the ammonium salt solution again, repeating the operation for cyclic exchanging, and washing the spherical molecular sieve after exchanging for 6 times to obtain an ammonia A type molecular sieve; wherein the ammonium salt solution is an ammonium sulfate solution; the concentration of the ammonium salt solution is 1mol/L; the solid-to-liquid ratio of the spherical molecular sieve to the ammonium salt solution is 1g:5mL; the water washing is to wash the exchanged spherical molecular sieve until the sulfate radical content is less than 200ppm.
(3) Mixing the ammonia A type molecular sieve obtained in the step (2) with lithium salt solution, adding lithium hydroxide to adjust the PH of the exchange liquid to 10, stirring and exchanging for 2 hours at the temperature of 60 ℃, discarding the exchange waste liquid after the exchange is completed, and adding the lithium salt solution again to repeat the operation, wherein the total exchange time is 2 times. Washing 3 times after the exchange is completed, drying the molecular sieve at 150 ℃ for 2 hours, and activating the molecular sieve at 550 ℃ for 1.5 hours to obtain the Li-A molecular sieve for the lithium electrolyte of the example 1, wherein the adsorption pore diameter is 0.4nm; wherein the lithium salt solution is lithium sulfate solution; the concentration of the lithium salt solution is 0.3mol/L; the dosage ratio of the ammonia A type molecular sieve to the lithium salt solution is 1g to 4.5mL.
Example 2
The Li-A type molecular sieve for lithium electrolyte of the embodiment adopts a preparation method comprising the following steps:
(1) Mixing 4A type molecular sieve raw powder and clay, and then placing the mixed powder into a rotary forming machine to contact with water for rolling forming to obtain spherical particles with the diameter of 1.0-2.0 mm; then drying the spherical particles at 200 ℃ until the water content is less than 10%, and calcining at 760 ℃ for 2 hours until the water content is less than 1%, thus obtaining the spherical molecular sieve; wherein the mass ratio of the 4A molecular sieve raw powder to the clay to the water is 100:10:13; the clay is kaolin;
crystallizing the spherical molecular sieve in 80g/L sodium hydroxide solution for 4 hours according to the ratio of 1g to 5mL, and then washing to obtain the 4A crystal-transformation spherical molecular sieve;
(2) Mixing the 4A crystal-transformation spherical molecular sieve obtained in the step (1) with an ammonium salt solution, regulating the pH value of the exchange liquid to 9 by ammonia water, stirring and exchanging for 2 hours at the temperature of 65 ℃, discarding the exchange waste liquid after exchanging, adding the ammonium salt solution again, repeating the operation for cyclic exchanging, and washing the spherical molecular sieve after exchanging for 6 times to obtain an ammonia A type molecular sieve; wherein the ammonium salt solution is an ammonium sulfate solution; the concentration of the ammonium salt solution is 1mol/L; the solid-to-liquid ratio of the spherical molecular sieve to the ammonium salt solution is 1g:5mL; the water washing is to wash the exchanged spherical molecular sieve until the sulfate radical content is less than 200ppm.
(3) Mixing the ammonia A type molecular sieve obtained in the step (2) with lithium salt solution, adding lithium hydroxide to adjust the PH of the exchange liquid to 10, stirring and exchanging for 2 hours at the temperature of 60 ℃, discarding the exchange waste liquid after the exchange is completed, and adding the lithium salt solution again to repeat the operation, wherein the total exchange time is 3 times. Washing 3 times after the exchange is completed, drying the molecular sieve at 150 ℃ for 2 hours, and activating the molecular sieve at 550 ℃ for 1.5 hours to obtain the Li-A molecular sieve for the lithium electrolyte of the example 2, wherein the adsorption pore diameter is 0.4nm; wherein the lithium salt solution is lithium sulfate solution; the concentration of the lithium salt solution is 0.3mol/L; the dosage ratio of the ammonia A type molecular sieve to the lithium salt solution is 1g to 4.5mL.
Example 3
The Li-A type molecular sieve for lithium electrolyte of the embodiment adopts a preparation method comprising the following steps:
(1) Mixing 4A type molecular sieve raw powder and clay, and then placing the mixed powder into a rotary forming machine to contact with water for rolling forming to obtain spherical particles with the diameter of 1.0-2.0 mm; then drying the spherical particles at 200 ℃ until the water content is less than 10%, and calcining at 760 ℃ for 2 hours until the water content is less than 1%, thus obtaining the spherical molecular sieve; wherein the mass ratio of the 4A molecular sieve raw powder to the clay to the water is 100:10:13; the clay is kaolin;
crystallizing the spherical molecular sieve in 80g/L sodium hydroxide solution for 4 hours according to the ratio of 1g to 5mL, and then washing to obtain the 4A crystal-transformation spherical molecular sieve;
(2) Mixing the 4A crystal-transformation spherical molecular sieve obtained in the step (1) with an ammonium salt solution, regulating the pH value of the exchange liquid to 9 by ammonia water, stirring and exchanging for 2 hours at the temperature of 65 ℃, discarding the exchange waste liquid after exchanging, adding the ammonium salt solution again, repeating the operation for cyclic exchanging, wherein the total exchanging time is 9 times, and washing the spherical molecular sieve after exchanging to obtain an ammonia A type molecular sieve; wherein the ammonium salt solution is an ammonium sulfate solution; the concentration of the ammonium salt solution is 1mol/L; the solid-to-liquid ratio of the spherical molecular sieve to the ammonium salt solution is 1g:5mL; the water washing is to wash the exchanged spherical molecular sieve until the sulfate radical content is less than 200ppm.
(3) Mixing the ammonia A type molecular sieve obtained in the step (2) with lithium salt solution, adding lithium hydroxide to adjust the PH of the exchange liquid to 10, stirring and exchanging for 2 hours at the temperature of 60 ℃, discarding the exchange waste liquid after the exchange is completed, and adding the lithium salt solution again to repeat the operation, wherein the total exchange time is 2 times. Washing 3 times after the exchange is completed, drying the molecular sieve at 150 ℃ for 2 hours, and activating the molecular sieve at 550 ℃ for 1.5 hours to obtain the Li-A molecular sieve for the lithium electrolyte of the example 3, wherein the adsorption pore diameter is 0.4nm; wherein the lithium salt solution is lithium sulfate solution; the concentration of the lithium salt solution is 0.3mol/L; the dosage ratio of the ammonia A type molecular sieve to the lithium salt solution is 1g to 4.5mL.
Example 4
The Li-A type molecular sieve for lithium electrolyte of the embodiment adopts a preparation method comprising the following steps:
(1) Mixing 4A type molecular sieve raw powder and clay, and then placing the mixed powder into a rotary forming machine to contact with water for rolling forming to obtain spherical particles with the diameter of 1.0-2.0 mm; then drying the spherical particles at 200 ℃ until the water content is less than 10%, and calcining at 760 ℃ for 2 hours until the water content is less than 1%, thus obtaining the spherical molecular sieve; wherein the mass ratio of the 4A molecular sieve raw powder to the clay to the water is 100:10:13; the clay is kaolin;
crystallizing the spherical molecular sieve in 80g/L sodium hydroxide solution for 4 hours according to the ratio of 1g to 5mL, and then washing to obtain the 4A crystal-transformation spherical molecular sieve;
(2) Mixing the 4A crystal-transformation spherical molecular sieve obtained in the step (1) with an ammonium salt solution, regulating the pH value of the exchange liquid to 9 by ammonia water, stirring and exchanging for 2 hours at the temperature of 65 ℃, discarding the exchange waste liquid after exchanging, adding the ammonium salt solution again, repeating the operation for cyclic exchanging, wherein the total exchanging time is 9 times, and washing the spherical molecular sieve after exchanging to obtain an ammonia A type molecular sieve; wherein the ammonium salt solution is an ammonium sulfate solution; the concentration of the ammonium salt solution is 1mol/L; the solid-to-liquid ratio of the spherical molecular sieve to the ammonium salt solution is 1g:5mL; the water washing is to wash the exchanged spherical molecular sieve until the sulfate radical content is less than 200ppm.
(3) Mixing the ammonia A type molecular sieve obtained in the step (2) with lithium salt solution, adding lithium hydroxide to adjust the PH of the exchange liquid to 10, stirring and exchanging for 2 hours at the temperature of 60 ℃, discarding the exchange waste liquid after the exchange is completed, and adding the lithium salt solution again to repeat the operation, wherein the total exchange time is 3 times. Washing 3 times after the exchange is completed, drying the molecular sieve at 150 ℃ for 2 hours, and activating the molecular sieve at 550 ℃ for 1.5 hours to obtain the Li-A molecular sieve for the lithium electrolyte of the example 4, wherein the adsorption pore diameter is 0.4nm; wherein the lithium salt solution is lithium sulfate solution; the concentration of the lithium salt solution is 0.3mol/L; the dosage ratio of the ammonia A type molecular sieve to the lithium salt solution is 1g to 4.5mL.
Comparative example 1
The preparation method of the Li-A type molecular sieve of the comparative example is basically the same as that of example 1, and the difference between the two is that: the molecular sieve of comparative example 1 is prepared by exchanging 4A molecular sieve raw powder, and then molding, drying and calcining. The method comprises the following specific steps:
(1) Adding ammonium sulfate solution (1 mol/L) into 4A type molecular sieve raw powder according to the proportion of 1g to 5mL, regulating the pH value of the system to 9 by adopting ammonia water, stirring and exchanging for 2h at 65 ℃, discarding exchange waste liquid after the exchange is finished, adding ammonium salt solution again, repeating the operation for cyclic exchange, and the total exchange times is 6 times. And (3) washing the spherical molecular sieve with water until the sulfate radical content is less than 200ppm after the exchange is completed, so as to obtain ammonia A type molecular sieve raw powder.
(2) Mixing the ammonia A molecular sieve raw powder obtained in the step (1) with lithium sulfate solution (0.3 mol/L) according to the ratio of 1g to 4.5mL, adding lithium hydroxide to adjust the PH of the exchange liquid to 10, stirring and exchanging for 2 hours at the temperature of 60 ℃, discarding the exchange waste liquid after the exchange is completed, and adding the lithium salt solution again to repeat the operation, wherein the total exchange times are 2 times. And washing 3 times after the exchange is completed to obtain the Li ion A-containing molecular sieve raw powder.
(3) Mixing the Li ion A-containing molecular sieve raw powder obtained in the step (2) with clay, and then placing the mixed powder into a rotary forming machine to contact with water for rolling forming to obtain spherical particles with the diameter of 1.0-2.0 mm; then drying the spherical particles at 200 ℃ until the water content is less than 10%, and calcining for 2 hours at 760 ℃ until the water content is less than 1%, thus obtaining the spherical LiA type molecular sieve; wherein, the mass ratio of the LiA molecular sieve raw powder to the clay to the water is 100:10:13; the clay is kaolin.
Comparative example 2
The preparation method of the Li-A type molecular sieve of the comparative example is basically the same as that of example 1, and the difference between the two is that: the total number of exchanges in step (3) is 1.
Comparative example 3
The preparation method of the Li-A type molecular sieve of the comparative example is basically the same as that of example 3, and the difference between the two is that: the total number of exchanges in step (3) is 1.
Test examples
The contents of sodium, potassium and calcium elements in the molecular sieves prepared in examples 1 to 4 and comparative examples 1 to 3 were tested using a flame photometer, and then Li in the molecular sieves was measured using a flame photometer 2 The O content was further measured according to the GB/T6287-2021 static water adsorption method, and the results are shown in Table 1.
Table 1 molecular sieve performance test results for examples 1-4 and comparative examples 1-3
The molecular sieves prepared in examples 1 to 4 and comparative examples 1 to 3 were further used in the dehydration of lithium bis (fluorosulfonyl) imide electrolyte, 10g of Li-A molecular sieve was added per 100mL of lithium bis (fluorosulfonyl) imide electrolyte, and the water content and Na and K content in the lithium bis (fluorosulfonyl) imide electrolyte were measured after 24h of adsorption. The results are shown in Table 2.
Table 2 dewatering effects of molecular sieves of examples 1 to 4 and comparative examples 1 to 3 on lithium bis-fluorosulfonyl imide electrolytes
As is clear from the results in Table 1 and Table 2, the molecular sieve prepared by the invention is a Li ion modified A-type adsorbent molecular sieve, and the content of Na and K elements is extremely low, so that metal sodium and potassium ions are not carried in or only slightly carried in the dehydration process of the lithium difluorosulfimide electrolyte, and the electrolyte is not damaged. In particular, the molecular sieve provided by the invention has the static water adsorption amount of more than 26.7%, is obviously superior to the existing molecular sieve water scavenger, is very suitable for being used as the water scavenger of the lithium bis (fluorosulfonyl) imide electrolyte, and has a good industrial application prospect.

Claims (10)

1. A method for preparing a Li-a type molecular sieve for lithium electrolyte, comprising the steps of:
(1) Shaping 4A type molecular sieve raw powder into spherical particles with the diameter of 1.0-2.0 mm, and then drying and calcining to obtain a spherical molecular sieve; crystallizing the spherical molecular sieve in an alkali solution, and then washing the spherical molecular sieve with water to obtain a 4A crystal-transformation spherical molecular sieve;
(2) Mixing the 4A crystal-sphere molecular sieve with an ammonium salt solution, and then circularly exchanging for 6-9 times at the temperature of 60-85 ℃, and washing after exchange to obtain an ammonia A molecular sieve;
(3) Mixing the ammonia A type molecular sieve with lithium salt solution, then circularly exchanging for 2-5 times at 50-95 ℃, and drying and activating after the exchange is completed to obtain the Li-A type molecular sieve for lithium electrolyte.
2. The method for producing a Li-a type molecular sieve for lithium electrolyte according to claim 1, wherein in step (1), the molding is specifically: mixing 4A type molecular sieve raw powder and clay, and then placing the mixed powder in a rotary forming machine to contact with water for rolling forming to obtain spherical particles; the drying and calcining are that spherical particles are dried at the temperature of 150-200 ℃ until the water content is less than 10%, and then calcined at the temperature of 680-900 ℃ until the water content is less than 1%; the mass ratio of the 4A type molecular sieve raw powder to the clay to the water is 100:8-12:10-15; the clay is one or two of kaolin and crucible clay.
3. The method for producing a Li-a type molecular sieve for lithium electrolyte according to claim 1, wherein in the step (1), the alkali solution is a sodium hydroxide solution of 60 to 100 g/L; the dosage ratio of the spherical molecular sieve to the alkali solution is 1g to (4-6) mL; the crystallization time is 3-5 h.
4. The method for producing a Li-a type molecular sieve for lithium electrolyte according to claim 1, wherein in step (2), the ammonium salt solution is an ammonium sulfate solution or an ammonium nitrate solution; the concentration of the ammonium salt solution is 1-2 mol/L; the dosage ratio of the spherical molecular sieve to the ammonium salt solution is 1g to (3-8) mL.
5. The method for producing a Li-a type molecular sieve for lithium electrolyte according to claim 1, wherein in step (2), the cyclic exchange is specifically: mixing spherical molecular sieve with ammonium salt solution, stirring and exchanging at 60-85 deg.c for 2-4 hr, eliminating waste exchange liquid, adding ammonium salt solution again, and repeating the above steps for 6-9 times.
6. The method for producing a Li-a type molecular sieve for a lithium electrolyte according to any one of claims 1 to 5, wherein in the step (3), the lithium salt solution is a lithium sulfate solution or a lithium nitrate solution; the concentration of the lithium salt solution is 0.2-0.5 mol/L; the dosage ratio of the ammonia A type molecular sieve to the lithium salt solution is 1g to (2-6) mL.
7. The method for producing a Li-a type molecular sieve for a lithium electrolyte according to any one of claims 1 to 5, wherein in step (3), the cyclic exchange is specifically: mixing ammonia A type molecular sieve with lithium salt solution, stirring and exchanging for 1-3 h at 50-95 ℃, discarding the exchanged waste liquid after exchanging, adding lithium salt solution again, repeating the above operation, and the total number of cyclic exchanges is 2-5.
8. The method for preparing a Li-a type molecular sieve for a lithium electrolyte according to any one of claims 1 to 5, wherein in the step (3), the drying is to dry the exchanged molecular sieve at 140 to 160 ℃ for 1 to 3 hours; the activation is to activate the dried molecular sieve for 1-2 hours at 500-550 ℃.
9. A Li-a type molecular sieve for lithium electrolyte prepared by the preparation method according to any one of claims 1 to 8, wherein the adsorption pore size of the Li-a type molecular sieve for lithium electrolyte is 0.2 to 0.6nm.
10. Use of a Li-a type molecular sieve for lithium electrolyte according to claim 9, characterized in that: the fluorine-containing lithium sulfonyl imide electrolyte is applied to a water scavenger.
CN202310543278.2A 2023-05-15 2023-05-15 Li-A type molecular sieve for lithium electrolyte and preparation method and application thereof Pending CN116750776A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4503024A (en) * 1981-09-14 1985-03-05 Compagnie Francaise De Raffinage Process for the preparation of synthetic zeolites, and zeolites obtained by said process
CN102500315A (en) * 2011-10-10 2012-06-20 于向真 LiX molecular sieve adsorbent and preparation method thereof
CN112588258A (en) * 2021-03-03 2021-04-02 苏州立昂新材料有限公司 Composite A-type molecular sieve raw powder containing wave absorbing material and full-zeolite molecular sieve, and preparation method and application thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4503024A (en) * 1981-09-14 1985-03-05 Compagnie Francaise De Raffinage Process for the preparation of synthetic zeolites, and zeolites obtained by said process
CN102500315A (en) * 2011-10-10 2012-06-20 于向真 LiX molecular sieve adsorbent and preparation method thereof
CN112588258A (en) * 2021-03-03 2021-04-02 苏州立昂新材料有限公司 Composite A-type molecular sieve raw powder containing wave absorbing material and full-zeolite molecular sieve, and preparation method and application thereof

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