A fluorinated lithium sulfonate electrolyte mother solution and its preparation method and application

Abstract

The present invention provides a fluorinated lithium sulfonate electrolyte mother liquor and a preparation method and application thereof. The preparation method comprises the following steps: reacting a halogenated sulfonyl and a lithiation agent in an organic solvent, and limiting the lithiation agent to include any one of lithium hydroxide, lithium bicarbonate or lithium carbonate or a combination of at least two thereof, so that the generated lithium fluoride sulfonate is directly dissolved in the organic solvent to obtain the fluorinated lithium sulfonate electrolyte mother liquor. The preparation method is simple to operate, and the raw materials used are low in price and low in danger. The prepared fluorinated lithium sulfonate electrolyte mother liquor has high purity of lithium fluoride sulfonate and low Cl content. ‑ and SO4 2‑ The low content provides a new idea for the preparation of fluorinated lithium sulfonate electrolyte.

Description

Technical Field

[0001] The invention belongs to the technical field of electrolytes, and in particular relates to an electrolyte mother solution containing fluorine-containing lithium sulfonate, and a preparation method and application thereof. Background Art

[0002] As an electrolyte additive for lithium-ion batteries, lithium fluorosulfonate can form a dense low-impedance SEI film on the negative electrode surface of lithium-ion batteries during operation, thereby greatly improving the rate performance and cycle performance of lithium-ion batteries. Therefore, lithium fluorosulfonate has been widely used in electrolytes for lithium-ion batteries.

[0003] Patent Publication No. CN103492319A discloses a method for manufacturing lithium fluorosulfonate, the preparation method includes a reaction process of reacting a lithium salt and fluorosulfonic acid in a non-aqueous solvent, the preparation method limits the lithium salt to a lithium salt that does not produce water due to the reaction process, further limits the lithium salt to a lithium halide, and limits the non-aqueous solvent used in the reaction process to a linear carbonate. Patent Publication No. CN105129825A discloses a non-aqueous electrolyte and a preparation method thereof, the electrolyte contains lithium fluorosulfonate, a lithium salt other than lithium fluorosulfonate, and a non-aqueous solvent, the non-aqueous electrolyte uses fluorosulfonic acid to react with the lithium salt, so that the molar content of lithium fluorosulfonate in the obtained electrolyte is 0.0005 mol / L or more, and the molar content of sulfate ions in the non-aqueous electrolyte is 1.0×10 -7 mol / L and above 1.0×10 -2 However, the fluorosulfonic acid used in the preparation methods provided in the above two prior arts is a super acid, which is expensive and inherently dangerous, and is not suitable for use in large-scale industrial production of electrolytes.

[0004] Patent publication No. JP2016008145 discloses a method for preparing lithium fluorosulfonate by directly reacting sulfur trioxide with a suspension of LiF / HF. The preparation method is simple, has high atomic utilization and uses low cost raw materials. However, the sulfur trioxide and anhydrous hydrofluoric acid used are extremely dangerous chemicals. Therefore, the conditions for industrial production are very demanding. In actual production, it is difficult to have the conditions for using the above two raw materials at the same time. In addition, the reaction has relatively high requirements for equipment, which limits its further industrial application.

[0005] In summary, it can be found that the preparation method of lithium fluorosulfonate provided in the existing technology has the problems of low purity of the prepared lithium fluorosulfonate, expensive and dangerous raw materials used, and harsh preparation conditions, which limits the large-scale industrial development of lithium fluorosulfonate.

[0006] Therefore, it is a technical problem that needs to be solved urgently in the art to develop a method for preparing an electrolyte mother liquor containing lithium fluorine sulfonate, which has safe and readily available raw materials, simple reaction conditions and can produce lithium fluorine sulfonate with high purity. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention aims to provide a fluorinated lithium sulfonate electrolyte mother solution and a preparation method and application thereof. The preparation method successfully obtains a fluorinated lithium sulfonate electrolyte mother solution by reacting a halogenated sulfonyl and a lithiation agent in an organic solvent, further limiting the lithiation agent to include any one or a combination of at least two of lithium hydroxide, lithium bicarbonate or lithium carbonate. - and SO4 2- The invention discloses an electrolyte mother liquor of lithium fluoride sulfonate with low content; the preparation method also has the advantages of simple operation, safe and readily available raw materials, and provides a new idea for preparing the electrolyte of lithium fluoride sulfonate.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing an electrolyte mother liquor of fluorinated lithium sulfonate, the preparation method comprising: reacting a halogenated fluorine sulfonyl and a lithiating agent in an organic solvent to obtain the electrolyte mother liquor of the fluorinated lithium sulfonate; the lithiating agent comprises any one of lithium hydroxide, lithium bicarbonate or lithium carbonate, or a combination of at least two of them.

[0010] First, the preparation method provided by the present invention successfully obtains an electrolyte mother liquor containing lithium fluoride sulfonate by reacting a halogenated sulfonyl and a lithiating agent in an organic solvent, and limiting the lithiating agent to include any one of lithium hydroxide, lithium bicarbonate or lithium carbonate, or a combination of at least two of them; the essence of the reaction is that the halogenated sulfonyl reacts with trace water in the lithiating agent to obtain hydrogen halide gas and fluorosulfonic acid, and the obtained fluorosulfonic acid further reacts with the lithiating agent to generate lithium fluoride sulfonate and trace water, and the lithiating agent itself does not directly react with the halogenated sulfonyl; and since the reaction is carried out in an organic solvent, the obtained lithium fluoride sulfonate will directly dissolve in the organic solvent to obtain the electrolyte mother liquor containing lithium fluoride sulfonate, and the generated trace water can continue to participate in the subsequent reaction process, therefore, overall, the trace water in the lithiating agent is in a state of dynamic reaction equilibrium and can be regarded as a catalyst.

[0011] Secondly, the raw materials used in the preparation method provided by the present invention are safe, readily available and inexpensive, the entire preparation method is simple to operate, and the electrolyte mother liquor of lithium fluoride sulfonate can be obtained in one step, and the lithium fluoride sulfonate in the prepared electrolyte mother liquor of lithium fluoride sulfonate has high purity and low Cl - and SO4 2-The content is low. The electrolyte mother liquor refers to a solution that can be used to prepare an electrolyte. When used, it can be directly used as an electrolyte by adding a corresponding proportion of carbonate organic solvent or carboxylate organic solvent to dilute it, eliminating the processes of lithium fluorosulfonate crystallization, drying and redissolution in the traditional preparation method, which provides a new method for electrolytes containing lithium fluorosulfonate.

[0012] Finally, in the actual operation process, the lithium reagent can be first dissolved in an organic solvent to prepare a suspension, and then the gaseous halofluorosulfonyl is introduced into the suspension to react to obtain the electrolyte mother solution of the fluorinated lithium sulfonate.

[0013] Preferably, the halofluorosulfonyl includes bisfluorosulfonyl and / or chlorofluorosulfonyl.

[0014] In the present invention, the selection range of the raw materials for the reaction is very wide. On the one hand, if the halofluorosulfonyl is bisfluorosulfonyl, the bisfluorosulfonyl can react with trace water in the lithiation reagent to generate hydrogen fluoride and fluorosulfonic acid. On the other hand, if the halofluorosulfonyl is other halofluorosulfonyl except bisfluorosulfonyl, the halogen atoms in the other halofluorosulfonyl are more easily replaced than fluorine atoms. Therefore, reacting the halofluorosulfonyl and the lithiation reagent in an organic solvent is actually a process in which the fluorine in the halofluorosulfonyl reacts with the trace water in the lithiation reagent to generate hydrogen halide gas and fluorosulfonic acid.

[0015] Preferably, the halofluorosulfonyl is prepared by the following method, which comprises: reacting a sulfonyl halide with a fluorination agent to obtain the halofluorosulfonyl.

[0016] As a preferred technical solution of the present invention, the halofluorosulfonyl as one of the raw materials can be prepared by reacting a sulfonyl halide with a fluorination agent. The sulfonyl halide and the fluorination agent have lower costs and are easier to obtain.

[0017] In the actual operation process, the fluorination reagent can be dissolved in an organic solvent to prepare a mixed solution containing the fluorination reagent; then the sulfonyl halide is also dissolved in the organic solvent to obtain a mixed solution containing the sulfonyl halide; finally, the mixed solution containing the sulfonyl halide is added dropwise to the mixed solution containing the fluorination reagent to react and obtain gaseous halofluorosulfonyl.

[0018] Preferably, the sulfonyl halide comprises sulfonyl chloride and / or sulfonyl chloride fluoride.

[0019] Preferably, the sulfonyl chloride is reacted with a fluorination agent to obtain the bisfluorosulfonyl and / or chlorofluorosulfonyl.

[0020] Preferably, the sulfonyl chloride is reacted with a fluorinating agent to obtain the bisfluorosulfonyl.

[0021] Preferably, the fluorination agent includes any one of potassium fluoride, ammonium fluoride, lithium fluoride, sodium fluoride, potassium bifluoride, ammonium bifluoride, sodium bifluoride, lithium bifluoride, hydrogen fluoride, antimony trifluoride or diethylaminosulfur trifluoride, or a combination of at least two thereof.

[0022] Preferably, the molar ratio of the sulfonyl halide to the fluorine in the fluorination agent is 1:(1-5), for example, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4 or 1:4.5, and more preferably 1:(1-3).

[0023] Preferably, the molar ratio of the halofluorosulfonyl to the lithium in the lithiating agent is 1:(1-5), such as 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4 or 1:4.5, etc., preferably 1:(1-3).

[0024] Preferably, the water content in the lithiation reagent is 50 to 5000 ppm, for example, 100 ppm, 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm or 4500 ppm.

[0025] The preparation method provided in the present invention can control the reaction speed by regulating the initial amount of trace water in the lithium reagent, thereby ensuring that the reaction process in the entire preparation method is slow and the reaction conditions are mild; and as a preferred technical solution of the present invention, selecting a lithium reagent with a water content of 50 to 5000 ppm as a raw material can make the obtained product purity higher. On the one hand, if the content of trace water in the lithium reagent is lower than 50 ppm, the reaction time will be too long, thereby reducing the yield of the reaction; on the other hand, if the content of trace water in the lithium reagent is higher than 5000 ppm, the reaction product will be hydrolyzed in water to produce corresponding increases in fluoride ions and sulfate ions, and the sulfate ions in the product will increase significantly, reducing the purity of the product; therefore, in the present invention, the optimal content of trace water is 50 to 5000 ppm.

[0026] Preferably, the organic solvent includes any one of a carbonate organic solvent, a carboxylate organic solvent, an ether organic solvent or a sulfone organic solvent, or a combination of at least two thereof.

[0027] Preferably, the carbonate organic solvent includes any one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate or propylene carbonate, or a combination of at least two thereof.

[0028] Preferably, the carboxylate organic solvent includes any one or a combination of at least two of ethyl acetate, ethyl propionate, propyl propionate, γ-butyrolactone, methyl acetate, methyl butyrate, ethyl butyrate or propyl butyrate;

[0029] Preferably, the ether organic solvent includes any one of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether or tetrafluoroethyl tetrafluoropropyl ether, or a combination of at least two thereof;

[0030] Preferably, the sulfone organic solvent includes any one of sulfolane, dimethyl sulfone or diphenyl sulfone, or a combination of at least two thereof;

[0031] Preferably, the mass percentage of the organic solvent in the electrolyte mother liquor is 80-99.5%, for example, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96% or 98%, and more preferably 90-95%.

[0032] Preferably, the reaction is carried out under inert gas conditions, more preferably under nitrogen or argon conditions.

[0033] Preferably, the volume percentage of the inert gas in all gases in the reaction system is 0-70% and not equal to 0, such as 10%, 20%, 30%, 40%, 50% or 60%, etc., more preferably 40-60%.

[0034] In the present invention, since the halofluorosulfonyl reacts with trace water in the lithiating reagent to produce hydrogen halide gas, the presence of hydrogen halide gas may directly react with the lithium salt to generate corresponding water and lithium halide salt; therefore, in order to avoid the generation of excessive halide ions, it is necessary to ensure an excess of lithium salt in the system and to carry out the reaction under the protection of a certain inert gas atmosphere. Controlling the volume content of the inert gas to 40-60% of the total gas content of the system can maximize the reaction purity.

[0035] Preferably, the reaction temperature is 0-50°C, for example, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C or 45°C.

[0036] Preferably, the reaction time is 10 to 20 h, for example, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h or 19 h.

[0037] It should be noted that the reaction time refers to the time after the halofluorosulfonyl is completely introduced into the organic solvent suspension containing the lithiating agent.

[0038] Preferably, after the reaction is completed, the steps of dehydration and purification are further included.

[0039] Preferably, the dehydration is performed by adding a dehydrating agent.

[0040] Preferably, the dehydrating agent comprises any one of molecular sieves, anhydrous sulfate or thionyl chloride, or a combination of at least two thereof.

[0041] Preferably, the dehydration time is 10 to 20 hours, for example, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours or 19 hours.

[0042] Preferably, the purification is performed by filtration or rotary evaporation.

[0043] As a preferred technical solution, the preparation method comprises the following steps:

[0044] (1) reacting a sulfonyl halide with a fluorination agent to obtain a halofluorosulfonyl;

[0045] (2) reacting the halofluorosulfonyl obtained in step (1) and a lithiation reagent in an organic solvent at 0 to 50° C. under inert gas protection for 10 to 20 hours, adding a dehydrating agent for dehydration for 10 to 20 hours, filtering or rotary evaporating to obtain the electrolyte mother liquor of the fluorinated lithium sulfonate.

[0046] In a second aspect, the present invention provides an electrolyte mother solution of fluorine-containing lithium sulfonate, wherein the electrolyte mother solution is prepared by the preparation method described in the first aspect.

[0047] Preferably, the mass percentage of lithium fluorosulfonate in the electrolyte mother solution is 0.5-20%, for example, 1%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16% or 18%.

[0048] In a third aspect, the present invention provides an electrolyte, wherein the electrolyte is prepared by the electrolyte mother solution as described in the second aspect.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] (1) The method for preparing the electrolyte mother liquor of fluorinated lithium sulfonate provided by the present invention comprises reacting a halogenated fluorinated sulfonyl and a lithiation reagent in an organic solvent to obtain the electrolyte mother liquor of the fluorinated lithium sulfonate; the raw materials used in the preparation method are low in risk, low in cost and easily available; and the equipment and instruments used in the preparation method are simple and suitable for industrial mass production.

[0051] (2) The mass percentage of lithium fluorosulfonate in the electrolyte mother liquor prepared by the preparation method provided by the present invention is 0.5-20%, and can be directly configured into an electrolyte for use, eliminating the processes of lithium fluorosulfonate crystallization, drying and redissolution, thereby providing a new preparation method for preparing an electrolyte containing lithium fluorosulfonate.

[0052] (3) Specifically, the purity of lithium fluorosulfonate IC in the electrolyte mother solution obtained by the preparation method provided by the present invention is above 97.3%, the yield of lithium fluorosulfonate is above 42.7%, and the product Cl - The content is not higher than 2842ppm, and the product SO4 2- The content is not higher than 3698ppm. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. Additional aspects and advantages of the present invention will be given in part in the following description, and part will become apparent from the following description, or will be understood through the practice of the present invention. It should be understood that the following description is only used to explain the present invention and is not intended to limit the present invention.

[0054] As used herein, the terms "comprises," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0055] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0056] When amount, concentration or other value or parameter is expressed as range, preferred range or a series of upper preferred value and lower preferred value limit range, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value and any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when disclosing range "1 to 5", described range should be interpreted as including range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5" etc. When numerical range is described in this article, unless otherwise stated, the range is intended to include its end value and all integers and fractions within the range.

[0057] Singular forms include plural references unless the context clearly indicates otherwise. "Optional" or "either" means that the subsequently described event or incident may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

[0058] The indefinite articles "a" and "an" before the elements or components of the present invention have no limitation on the quantity requirements (i.e. the number of occurrences) of the elements or components. Therefore, "a" or "an" should be interpreted as including one or at least one, and the elements or components in the singular form also include the plural form, unless the quantity obviously refers to the singular form only.

[0059] The terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" described in the present invention mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example.

[0060] Moreover, the technical features involved in various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0061] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0062] Example 1

[0063] A method for preparing a mother solution of an electrolyte containing fluorinated lithium sulfonate, the method comprising the following steps:

[0064] (1) Add 0.15 mol of antimony trifluoride (SbF3) to 50 mL of dimethyl carbonate (DMC) solvent, connect the gas passage, and then gradually add 50 mL of SO2Cl2 / DMC solution containing 0.25 mol of sulfonyl chloride (SO2Cl2) thereto for 2 h to obtain halofluorosulfonyl gas;

[0065] (2) At 5° C., the halofluorosulfonyl gas obtained in step (1) was mixed with a nitrogen flow at a flow rate of 100 mL / min, and 300 mL of a LiOH / DMC solution containing 0.275 mol of LiOH (trace water content of 633 ppm) was introduced together; after the introduction of the halofluorosulfonyl gas was stopped, nitrogen was continued to react for 18 hours, unreacted LiOH was filtered out, 0.67 g of dichlorothionyl was added, and after sufficient stirring to remove water, the solution was repeatedly concentrated and diluted to obtain the electrolyte mother solution of the fluorinated lithium sulfonate.

[0066] Example 2

[0067] A method for preparing a mother solution of an electrolyte containing fluorinated lithium sulfonate, the method comprising the following steps:

[0068] (1) introducing anhydrous hydrogen fluoride (AHF) into a cryogenically frozen DMC solvent to obtain a HF / DMC mixed solution having a HF mass percentage of 20%;

[0069] (2) taking 50 mL of the HF / DMC mixed solution obtained in step (1), adding 0.25 mol of KF solid to obtain a KHF2 solution;

[0070] (3) Connect the gas passage, and then gradually add 50 mL of SO2Cl2 / DMC solution containing 0.25 mol SO2Cl2 to the KHF2 solution obtained in step (2) for 2 h to obtain halofluorosulfonyl gas;

[0071] (4) The halofluorosulfonyl gas obtained in step (3) was mixed with a nitrogen flow at a flow rate of 100 mL / min at 5° C., and introduced into 300 mL of a LiOH / DMC solution containing 0.275 mol of LiOH (trace water content of 633 ppm). After the introduction of the halofluorosulfonyl gas was stopped, the nitrogen was continued to react for 18 h, and the unreacted LiOH was filtered out. 0.97 g of dichlorothionyl was added, and after sufficient stirring to remove water, the solution was repeatedly concentrated and diluted to obtain the electrolyte mother solution of the fluorinated lithium sulfonate.

[0072] Example 3

[0073] A method for preparing a mother solution of an electrolyte containing fluorinated lithium sulfonate, the method comprising the following steps:

[0074] (1) introducing AHF into a cryogenically frozen DMC solvent to obtain an HF / DMC mixed solution having an HF content of 20% by weight;

[0075] (2) taking 50 mL of the HF / DMC mixed solution obtained in step (1), and then adding 0.25 mol of NH4F thereto to obtain NH4HF2 solution;

[0076] (3) Connect the gas passage, and then gradually add 50 mL of SO2Cl2 / DMC solution containing 0.25 mol of SO2Cl2 to the NH4HF2 solution obtained in step (2) for 2 h to obtain halofluorosulfonyl gas;

[0077] (4) The halofluorosulfonyl gas obtained in step (3) was mixed with a nitrogen flow at a flow rate of 100 mL / min at 5° C., and introduced into 300 mL of a LiOH / DMC solution containing 0.275 mol of LiOH (trace water content of 633 ppm). After the introduction of the halofluorosulfonyl gas was stopped, nitrogen was continued to react for 18 h, 0.51 g of dichlorothionyl was added, and after sufficient stirring to remove water, the solution was repeatedly concentrated and diluted to obtain the electrolyte mother solution of the fluorinated lithium sulfonate.

[0078] Example 4

[0079] A method for preparing a mother solution of an electrolyte containing fluorinated lithium sulfonate, the method comprising the following steps:

[0080] (1) Connect the gas passage, then gradually add 50 mL of SO2Cl2 / DMC solution containing 0.25 mol SO2Cl2 to 50 mL of DMC solution containing 1.25 mol KF for 2 h to obtain halofluorosulfonyl gas;

[0081] (2) The halofluorosulfonyl gas obtained in step (1) was mixed with a nitrogen flow at a flow rate of 100 mL / min at 5°C, and introduced into 300 mL of a LiOH / DMC solution containing 0.275 mol of LiOH (trace water content of 633 ppm). After the introduction of the halofluorosulfonyl gas was stopped, nitrogen was continued to react for 18 h, 1.33 g of dichlorothionyl was added, and after sufficient stirring to remove water, the solution was repeatedly concentrated and diluted to obtain the electrolyte mother solution of the fluorinated lithium sulfonate.

[0082] Example 5

[0083] A method for preparing an electrolyte mother liquor containing fluorinated lithium sulfonate, which differs from Example 2 in that step (4) uses LiHCO3 with a trace water content of 519 ppm to replace LiOH with a trace water content of 633 ppm, and other conditions and steps are the same as those in Example 2.

[0084] Example 6

[0085] A method for preparing an electrolyte mother liquor containing fluorinated lithium sulfonate, which differs from Example 2 in that, in step (4), 0.1375 mol Li2CO3 with a trace water content of 471 ppm is used to replace LiOH with a trace water content of 633 ppm, and other conditions and steps are the same as those in Example 2.

[0086] Example 7

[0087] A method for preparing a fluorinated lithium sulfonate electrolyte mother liquor, which differs from Example 2 in that step (4) uses 0.1375 mol Li2CO3 with a trace water content of 23 ppm to replace LiOH with a trace water content of 633 ppm, and other conditions and steps are the same as those in Example 2.

[0088] Example 8

[0089] A method for preparing an electrolyte mother liquor containing fluorinated lithium sulfonate, which differs from Example 2 in that, in step (4), 0.1375 mol Li2CO3 with a trace water content of 1475 ppm is used to replace LiOH with a trace water content of 633 ppm, and other conditions and steps are the same as those in Example 2.

[0090] Example 9

[0091] A method for preparing an electrolyte mother liquor containing fluorinated lithium sulfonate, which differs from Example 2 in that step (4) uses LiOH with a trace water content of 87 ppm to replace LiOH with a trace water content of 633 ppm, and other conditions and steps are the same as those in Example 2.

[0092] Example 10

[0093] A method for preparing an electrolyte mother liquor containing fluorinated lithium sulfonate, which differs from Example 2 in that step (4) uses LiOH with a trace water content of 4352 ppm to replace LiOH with a trace water content of 633 ppm, and other conditions and steps are the same as those in Example 2.

[0094] Embodiment 11

[0095] A method for preparing an electrolyte mother liquor containing fluorinated lithium sulfonate, which differs from Example 2 in that step (4) uses LiOH with a trace water content of 15000 ppm to replace LiOH with a trace water content of 633 ppm, and other conditions and steps are the same as those in Example 2.

[0096] Example 12

[0097] A method for preparing a fluorinated lithium sulfonate electrolyte mother liquor, which differs from Example 2 in that the molar number of LiOH with a trace water content of 633 ppm used in step (4) is 0.75 mol, and the other conditions and steps are the same as those in Example 2.

[0098] Embodiment 13

[0099] A method for preparing an electrolyte mother liquor containing fluorinated lithium sulfonate, which differs from Example 2 in that the molar number of LiOH with a trace water content of 633 ppm used in step (4) is 1.25 mol, and the other conditions and steps are the same as those in Example 2.

[0100] Embodiment 14

[0101] A method for preparing a fluorinated lithium sulfonate electrolyte mother liquor, which differs from Example 2 only in that nitrogen is not introduced in step (4), and other conditions and steps are the same as those in Example 2.

[0102] Embodiment 15

[0103] A method for preparing a fluorinated lithium sulfonate electrolyte mother liquor, which differs from Example 2 only in that the flow rate of nitrogen in step (4) is 50 mL / min, and the other conditions and steps are the same as those in Example 2.

[0104] Example 16

[0105] A method for preparing a mother solution of an electrolyte containing fluorinated lithium sulfonate, which differs from Example 2 only in that the flow rate of nitrogen in step (4) is 200 mL / min, and the other conditions and steps are the same as those in Example 2.

[0106] Embodiment 17

[0107] A method for preparing a fluorinated lithium sulfonate electrolyte mother liquor, which differs from Example 2 only in that the reaction temperature in step (4) is 25° C., and other conditions and steps are the same as those in Example 2.

[0108] Embodiment 18

[0109] A method for preparing a fluorinated lithium sulfonate electrolyte mother liquor, which differs from Example 2 only in that the reaction temperature in step (4) is 50° C., and other conditions and steps are the same as those in Example 2.

[0110] Embodiment 19

[0111] A method for preparing a fluorinated lithium sulfonate electrolyte mother liquor, which differs from Example 2 only in that molecular sieves are used in step (4) to replace thionyl chloride, and other conditions and steps are the same as those in Example 2.

[0112] Embodiment 20

[0113] A method for preparing a mother solution of an electrolyte containing fluorinated lithium sulfonate, which differs from Example 2 only in that, in step (3), thionyl chloride is not added for sufficient stirring to remove water, and repeated concentration and dilution are directly performed, and other conditions and steps are the same as those in Example 2.

[0114] Comparative Example 1

[0115] A method for preparing lithium fluorosulfonate, the method comprising the following steps:

[0116] (1) Under nitrogen protection, add 300 mL of DMC into a three-necked flask, then add 0.5 mol of lithium fluoride, and stir to form a suspension;

[0117] (2) At 25° C., 0.5 mol of chlorosulfonic acid was dropwise added to the suspension obtained in step (1). During the dropwise addition, the hydrogen chloride gas generated by the reaction was passed into a water absorption device. After reacting for 24 hours, the reaction solution was filtered, concentrated and crystallized to obtain a white solid product, which was then washed several times with dichloromethane and dried in vacuo to obtain the lithium fluorosulfonate.

[0118] Comparative Example 2

[0119] A method for preparing lithium fluorosulfonate, the method comprising the following steps:

[0120] (1) Under nitrogen protection, add 300 mL of DMC into a three-necked flask, then add 2 mol of lithium fluoride, and stir to form a suspension;

[0121] (2) 0.5 mol of chlorosulfonic acid is added dropwise to the suspension obtained in step (1) at 25° C. During the addition, the hydrogen chloride gas generated by the reaction is passed into a water absorption device. After reacting for 24 hours, the reaction solution is filtered, concentrated and crystallized. The obtained white solid product is washed several times with dichloromethane and dried in vacuo to obtain the lithium fluorosulfonate.

[0122] Comparative Example 3

[0123] A method for preparing lithium fluorosulfonate, the method comprising the following steps:

[0124] (1) introducing AHF into cryogenically frozen DMC to prepare an HF / DMC mixed solution having an HF content of 40% by weight;

[0125] (2) Under nitrogen protection, add 300 mL of the HF / DMC mixed solution obtained in step (1) into a three-necked flask, then add 0.5 mol of lithium fluoride to the mixed solution, and stir to form a suspension;

[0126] (3) adding 0.5 mol of chlorosulfonic acid dropwise to the suspension obtained in step (2) at 25° C., during the dropwise addition, the hydrogen fluoride mixed gas generated by the reaction is passed into a water absorption and alkali absorption device, reacting for 24 hours, heating the reaction system to volatilize the HF therein, and concentrating under reduced pressure to a white solid, adding dimethyl carbonate to dissolve it again and filtering it, and concentrating the filtrate by rotary evaporation to crystallize it, washing it with dichloromethane several times, and then drying it in vacuum to obtain the lithium fluorosulfonate.

[0127] Comparative Example 4

[0128] A method for preparing lithium fluorosulfonate, the method comprising the following steps:

[0129] (1) SO3 was introduced into a pre-cooled sealed three-necked flask to obtain white SO3 crystals. The mass of SO3 was measured by weight loss method to be 42 g (0.525 mol); AHF was introduced into a low-temperature frozen DMC solvent to prepare an HF / DMC mixed solution with a HF mass percentage of 40%;

[0130] (2) under nitrogen protection, 400 mL of the HF / DMC mixed solution obtained in step (1) was added to a polytetrafluoroethylene (PTFE) three-necked flask, and then 0.7 mol of lithium fluoride was added and stirred to form a suspension;

[0131] (3) heating the three-necked flask containing SO3 obtained in step (1) to gasify the SO3 and then passing it into the suspension obtained in step (2). After the addition is completed, the reaction is continued for 24 hours. The hydrogen fluoride gas generated during the reaction is passed into the alkali absorption device. After 24 hours of reaction, the reaction system turns black due to the strong dehydration of SO3, and the reaction fails.

[0132] Comparative Example 5

[0133] A method for preparing lithium fluorosulfonate, the method comprising the following steps:

[0134] (1) SO3 was introduced into a pre-cooled sealed three-necked flask to obtain white SO3 crystals. The mass of SO3 was measured by weight loss method to be 49 g (0.6125 mol); AHF was introduced into a low-temperature frozen dichloroethane solvent to prepare an HF / dichloroethane mixed solution with a HF mass percentage of 40%;

[0135] (2) Under nitrogen protection, 400 mL of the HF / dichloroethane mixed solution obtained in step (1) was added into a PTFE three-necked flask, and then 0.8 mol of lithium fluoride was added into the PTFE three-necked flask, and stirred to obtain a suspension;

[0136] (3) Heating the three-necked flask containing SO3 in step (1) to vaporize the SO3 and then passing it into the suspension obtained in step (2). After the ventilation is completed, the reaction is continued for 24 hours. The hydrogen fluoride gas generated during the reaction is passed into an alkali absorption device. After reacting for 24 hours, heating is performed to volatilize HF, and the mixture is concentrated under reduced pressure to a white solid. Dimethyl carbonate is added to dissolve it again and filtered. The filtrate is concentrated by rotary evaporation and crystallized, and washed with dichloromethane several times to obtain the lithium fluorosulfonate.

[0137] Comparative Example 6

[0138] A method for preparing lithium fluorosulfonate, the method comprising the following steps:

[0139] (1) SO3 was introduced into a pre-cooled sealed three-necked flask to obtain white SO3 crystals. The mass of SO3 was 35 g (0.4375 mol) measured by weight loss method; under nitrogen protection, 300 mL of dichloroethane solvent was added to the PTFE three-necked flask, and then 0.57 mol of lithium fluoride was added, and the mixture was stirred to form a suspension;

[0140] (2) heating the three-necked flask containing SO3 obtained in step (1) to vaporize the SO3 and then pass it into the suspension obtained in step (1). After the addition is completed, the reaction is continued for 24 hours. After the reaction is completed, the reaction system is heated and concentrated under reduced pressure to a white solid. Dimethyl carbonate is then added to dissolve and filter again. The filtrate is concentrated by rotary evaporation and crystallized, and washed with dichloromethane several times to obtain the lithium fluorosulfonate.

[0141] Comparative Example 7

[0142] A method for preparing a fluorinated lithium sulfonate electrolyte mother liquor, which differs from Example 2 only in that step (4) uses LiCl with a trace water content of 633 ppm to replace LiOH with a trace water content of 633 ppm, and other conditions and steps are the same as those in Example 2.

[0143] Comparative Example 8

[0144] A method for preparing an electrolyte mother liquor containing fluorinated lithium sulfonate, which differs from Example 2 only in that step (4) uses CH3COOLi with a trace water content of 633 ppm to replace LiOH with a trace water content of 633 ppm, and other conditions and steps are the same as those in Example 2.

[0145] Performance Test:

[0146] (1) IC purity: Perform IC chromatography test and calculate the ratio of the peak area of ​​lithium fluorosulfonate to the sum of the peak areas of all peaks in the IC spectrum to obtain the IC purity;

[0147] (2) Yield: lithium fluorosulfonate solutions of different concentrations are prepared using lithium fluorosulfonate solid to obtain a standard curve of lithium fluorosulfonate; based on the standard curve, the concentration C1 of lithium fluorosulfonate in the lithium fluorosulfonate mother solution and the mass M1 of lithium fluorosulfonate are determined; based on the feed amount, the theoretical mass of lithium fluorosulfonate is calculated as M2; the yield of lithium fluorosulfonate is obtained as =M1 / M2×100%;

[0148] (3) Product Cl - and SO4 2- Content: Determine Cl by turbidimetric titration - and SO4 2- The content.

[0149] The preparation methods provided in Examples 1 to 20 and Comparative Examples 1 to 8 were tested according to the above test method, and the test results are shown in Table 1:

[0150] Table 1

[0151]

[0152]

[0153] According to the data in Table 1, we can see that:

[0154] The purity of lithium fluorosulfonate IC in the electrolyte mother solution obtained by the preparation method provided in Examples 1 to 20 is above 97.3%, the yield of lithium fluorosulfonate is above 42.7%, and the product Cl - The content is not higher than 2842ppm, and the product SO4 2- The content is not higher than 3698ppm.

[0155] Comparing Examples 6 and 8 with Example 7, it can be found that the lithium reagent in the preparation method provided in Example 7 is Li2CO3 with a trace water content of 23 ppm. Due to the low trace water content, the yield of the prepared lithium fluorosulfonate is only 42.7%. Further comparison of Examples 2, 9, 10 and Example 11 shows that the lithium reagent in the preparation method provided in Example 11 is LiOH with a trace water content of 15000 ppm. Due to the high trace water content, the hydrolysis of chlorosulfonic acid increases, and the Cl in the final product is 1.34%. - and SO4 2- Similarly, increasing the molar ratio of lithium salt will also cause Cl in the product to a certain extent. - and SO4 2- The increase in impurity content may be due to the increase in hydrolysis side reactions caused by the moisture in the lithium salt and the alkaline environment.

[0156] Further comparison of Examples 1 to 4, 12 to 13, 15 to 16 and Example 14 shows that the absence of nitrogen in step (4) of the preparation method provided in Example 14 also leads to an increase in the hydrolysis of chlorosulfonic acid, and the Cl content in the final product is - and SO4 2- The content is relatively high.

[0157] Further comparison of Example 2 and Examples 17-18 shows that the reaction temperature in step (4) also affects the Cl content in the final product. - and SO4 2- content.

[0158] Comparing Examples 1 to 20 with Comparative Examples 1 to 3, it can be seen that the preparation methods provided in Comparative Examples 1 to 3 use chlorosulfonic acid and lithium fluoride to react to prepare lithium fluorosulfonate. Although the IC purity and yield of the obtained product are high, the Cl in the product is - and SO4 2- The content is also high (>5000ppm), which is due to the poor fluorination ability of lithium fluoride itself, and it is difficult to completely fluorinate the chlorine in chlorosulfonic acid into fluorine; and by comparing Comparative Example 1 and Comparative Example 2, it can be seen that simply increasing the amount of lithium fluoride is difficult to ensure complete fluorination of chlorosulfonic acid, and Comparative Example 3 introduces AHF, although LiHF2 can be prepared to fluorinate chlorosulfonic acid, and the fluorination effect is also greatly improved, but due to the presence of water in the system of the preparation method provided in Comparative Examples 1 to 3, it is inevitable that the chlorosulfonic acid in the system is partially hydrolyzed to produce Cl which is difficult to remove - and SO4 2- , so that the Cl in the final product - and SO4 2- The content is also high, which reduces the quality of the product.

[0159] Further comparison of Examples 1 to 4 and Comparative Examples 4 to 6 shows that Comparative Examples 4 to 6 use SO3 as a sulfonating agent to react with lithium fluoride to prepare lithium fluorosulfonate. Although the IC purity and yield of the lithium fluorosulfonate prepared by this method are relatively high, it is found during the reaction that in Comparative Example 4, since conventional dimethyl carbonate is used to absorb AHF, when SO3 is introduced for reaction, due to the strong oxidizing and dehydrating properties of SO3, dimethyl carbonate is dehydrated, carbonized and blackened, and the reaction fails. Comparative Example 5 uses SO3 and LiF / HF / DCE for reaction, and the obtained lithium fluorosulfonate solid has a higher purity, but the SO4 in the product is 2- The preparation method provided in Comparative Example 6 uses dichloroethane as the solvent. Due to the poor dispersibility of the lithium salt in dichloroethane and the poor lithiation effect of lithium fluoride, SO4 in the final product is also obtained. 2- The content is relatively high (>5000ppm).

[0160] Further comparison of Examples 1 to 20 and Comparative Examples 7 to 8 shows that it is difficult to obtain lithium fluorosulfonate in a short time due to the poor reactivity of halofluorosulfonyl with lithium chloride and lithium acetate.

[0161] In summary, only by selecting a suitable lithiating agent, limiting the amount of the lithiating agent and the content of trace water therein, and introducing nitrogen during the reaction, can the reaction proceed smoothly and a mother liquor of fluorinated lithium sulfonate electrolyte with high purity and yield and low impurity content be obtained.

[0162] The applicant declares that the present invention illustrates a fluorine-containing lithium sulfonate electrolyte mother solution and its preparation method and application through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a mother solution of an electrolyte containing fluorinated lithium sulfonate, characterized in that: The preparation method comprises: reacting a halofluorosulfonyl and a lithiation agent in an organic solvent to obtain an electrolyte mother solution of the fluorinated lithium sulfonate; The lithiation reagent includes any one of lithium hydroxide, lithium bicarbonate or lithium carbonate, or a combination of at least two thereof; The molar ratio of the halofluorosulfonyl to the lithium in the lithiation reagent is 1:(1-5); The water content in the lithium reagent is 50 to 5000 ppm; The reaction is carried out under inert gas conditions.

2. The preparation method according to claim 1, characterized in that: The halofluorosulfonyl includes bisfluorosulfonyl and / or chlorofluorosulfonyl.

3. The preparation method according to claim 2, characterized in that: The halofluorosulfonyl is prepared by the following method, which comprises: reacting a sulfonyl halide with a fluorination agent to obtain the halofluorosulfonyl.

4. The preparation method according to claim 3, characterized in that: The sulfonyl halide includes sulfonyl chloride and / or sulfonyl chloride fluoride.

5. The preparation method according to claim 4, characterized in that: The sulfonyl chloride reacts with a fluorination agent to obtain the bisfluorosulfonyl and / or chlorofluorosulfonyl.

6. The preparation method according to claim 4, characterized in that: The sulfonyl chloride fluoride reacts with a fluorination agent to obtain the bisfluorosulfonyl.

7. The preparation method according to claim 3, characterized in that: The fluorination agent includes any one of potassium fluoride, ammonium fluoride, lithium fluoride, sodium fluoride, potassium bifluoride, ammonium bifluoride, sodium bifluoride, lithium bifluoride, hydrogen fluoride, antimony trifluoride or diethylamino sulfur trifluoride, or a combination of at least two thereof.

8. The preparation method according to claim 3, characterized in that: The molar ratio of the sulfonyl halide to the fluorine in the fluorination agent is 1:(1-5).

9. The preparation method according to claim 8, characterized in that: The molar ratio of the sulfonyl halide to the fluorine in the fluorination agent is 1:(1-3).

10. The preparation method according to claim 1, characterized in that: The molar ratio of the halofluorosulfonyl to the lithium in the lithiating agent is 1:(1-3).

11. The preparation method according to claim 1, characterized in that: The organic solvent includes any one of a carbonate organic solvent, a carboxylate organic solvent, an ether organic solvent or a sulfone organic solvent, or a combination of at least two thereof.

12. The preparation method according to claim 11, characterized in that: The carbonate organic solvent includes any one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate or propylene carbonate, or a combination of at least two thereof.

13. The preparation method according to claim 11, characterized in that: The carboxylate organic solvent includes any one of ethyl acetate, ethyl propionate, propyl propionate, γ-butyrolactone, methyl acetate, methyl butyrate, ethyl butyrate or propyl butyrate, or a combination of at least two thereof.

14. The preparation method according to claim 11, characterized in that: The ether organic solvent includes any one of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether or tetrafluoroethyl tetrafluoropropyl ether, or a combination of at least two thereof.

15. The preparation method according to claim 11, characterized in that: The sulfone organic solvent includes any one of sulfolane, dimethyl sulfone or diphenyl sulfone, or a combination of at least two of them.

16. The preparation method according to claim 1, characterized in that: The mass percentage of the organic solvent in the electrolyte mother liquor is 80-99.5%.

17. The preparation method according to claim 16, characterized in that: The mass percentage of the organic solvent in the electrolyte mother liquor is 90-95%.

18. The preparation method according to claim 1, characterized in that: The reaction is carried out under nitrogen or argon conditions.

19. The preparation method according to claim 1, characterized in that: The volume percentage of inert gas in all gases in the reaction system is 0-70% and is not equal to 0.

20. The preparation method according to claim 19, characterized in that: The volume percentage of inert gas in all gases in the reaction system is 40-60%.

21. The preparation method according to claim 1, characterized in that: The reaction temperature is 0-50°C.

22. The preparation method according to claim 1, characterized in that: The reaction time is 10 to 20 h.

23. The preparation method according to claim 1, characterized in that: After the reaction is completed, the steps of dehydration and purification are also included.

24. The preparation method according to claim 23, characterized in that: The dehydration is performed by adding a dehydrating agent.

25. The preparation method according to claim 24, characterized in that: The dehydrating agent includes any one of molecular sieves, anhydrous sulfate or thionyl chloride, or a combination of at least two of them.

26. The preparation method according to claim 23, characterized in that: The dehydration time is 10 to 20 h.

27. The preparation method according to claim 23, characterized in that: The purification is carried out by filtration or rotary evaporation.

28. The preparation method according to claim 1, characterized in that: The preparation method comprises the following steps: (1) reacting a sulfonyl halide with a fluorination agent to obtain a halofluorosulfonyl; (2) reacting the halofluorosulfonyl obtained in step (1) and a lithiation reagent in an organic solvent at 0-50° C. and under inert gas conditions for 10-20 h, adding a dehydrating agent for dehydration for 10-20 h, filtering or rotary evaporating to obtain the electrolyte mother liquor of the fluorinated lithium sulfonate.

29. An electrolyte mother solution containing fluorinated lithium sulfonate, characterized in that: The electrolyte mother liquor is prepared by the preparation method according to any one of claims 1 to 28.

30. The electrolyte mother solution according to claim 29, characterized in that: The mass percentage of lithium fluorosulfonate in the electrolyte mother solution is 0.5-20%.

31. An electrolyte, characterized in that The electrolyte is prepared by the electrolyte mother solution as claimed in claim 29 or 30.

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