Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B21/00—Nitrogen; Compounds thereof
  • C01B21/082—Compounds containing nitrogen and non-metals and optionally metals
  • C01B21/086—Compounds containing nitrogen and non-metals and optionally metals containing one or more sulfur atoms
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C303/00—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides
  • C07C303/34—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides of amides of sulfuric acids
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
  • H01M10/0568—Liquid materials characterised by the solutes
• • 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
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
• • 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

Definitions

• the present invention generally relates to the field of lithium sulfonimide salts for electrolytes for lithium-based electrochemical devices.
• the present invention is directed to processes for removing reactive solvent from lithium bis(fluorosulfonyl)imide (LiFSI) using organic solvents that are stable toward anodes in lithium-ion and lithium-metal batteries.
• LiFSI lithium bis(fluorosulfonyl)imide
• LiFSI Lithium bis(fluorosulfonyl)imide
• electrolyte/additive in lithium-ion batteries due to its unique properties, such as excellent solubility, ionic conductivity comparable to LiPF 6 -based electrolytes, cost-effectiveness, environmental benignity, and favorable solid electrolyte interface (SEI) forming property.
• SEI solid electrolyte interface
• the level of purity of LiFSI used for battery electrolytes can be critical to the operation and cycle life of the batteries using LiFSI-based electrolytes.
• many commercial processes for synthesizing LiFSI produce byproducts that remain is the crude LiFSI produced by the synthesis processes.
• the main synthesis impurities in LiFSI are lithium fluoride (LiF), lithium chloride (LiCl), lithium sulfate (L12SO4), lithium fluorosulfonate (L1FSO3), and acidic-type impurities, for example, hydrogen fluoride (HF). These impurities must be removed, or reduced to various acceptable levels, before using LiFSI salt in a battery. However, they can be challenging to remove.
• Some processes for removing impurities from crude LiFSI utilize one or more solvents, such as alcohol(s) and water, that are reactive to lithium metal.
• crude LiFSI may contain water by mean other than being a solvent.
• the purified LiFSI contains residue(s) of the reactive solvent(s) used to remove the target impurities and/or water that may be otherwise present, and the reactive-solvent residue and/or water react with the lithium metal of the device’s anode, thereby destroying the integrity of the lithium metal and the ability of the anode to function properly.
• the reactive-solvent(s) in the LiFSI salt used to make the electrolyte can significantly impact the performance and cycle life of a secondary lithium-metal battery.
• the present disclosure is directed to a method of creating a reduced-reactive-solvent lithium bis(fluorosulfonyl) imide (LiFSI) product.
• the method includes providing a first crude LiFSI containing LiFSI and one or more reactive solvents; contacting the first crude LiFSI with at least one first anhydrous organic solvent under an inert condition to create a solution containing the first crude LiFSI and the one or more reactive solvents, wherein the solubility of the LiFSI in the at least one first anhydrous organic solvent is at least about 35% below 25oC; subjecting the solution to a vacuum so as to remove the at least one first anhydrous organic solvent and the one or more reactive solvents and obtain a solid mass; treating the solid mass with at least one second anhydrous organic solvent in which the LiFSI is insoluble to create a combination having an insoluble portion; isolating the insoluble portion in an inert atmosphere; flushing the insoluble portion with at least one dry inert gas so
• FIG. 1 is a flow diagram illustrating a multi-pass method of reducing the reactive solvent in lithium bis(fluorosulfonyl)imide (LiFSI) in accordance with aspects of the present disclosure
• FIG. 2 is a high-level diagram illustrating an electrochemical device made in accordance with aspects of the present disclosure
• FIG. 3 is a flow diagram illustrating a multi-pass method of purifying LiFSI in accordance with aspects of the present disclosure
• FIG. 4A is a graph of discharge capacity versus cycle number for a non-aqueous electrolyte utilizing LiFSI salt synthesized in accordance with aspects of this disclosure (upper line) and a like non-aqueous electrolyte utilizing a commercially purchased LiFSI salt (lower line); and
• FIG. 4B is a graph of capacity retention versus cycle number for a non-aqueous electrolyte utilizing LiFSI salt synthesized in accordance with aspects of this disclosure (upper line) and a like non-aqueous electrolyte utilizing a commercially purchased LiFSI salt (lower line).
• the present disclosure is directed to methods of removing one or more reactive solvents from crude lithium bis(fluorosulfonyl)imide (LiFSI).
• LiFSI crude lithium bis(fluorosulfonyl)imide
• the use of the term“reactive” to modify“solvent” or “solvents”, or the like shall mean that the solvent(s) is/are reactive to lithium metal within a lithium- based battery, such as lithium metal in the anode of a lithium-metal battery.
• “reactive” in this context refers to the magnitude of the reduction potential of lithium metal relative to the solvent(s).
• a reactive solvent has a reactive proton that has a relatively high reduction potential relative to lithium metal, which has a relatively low reduction potential.
• reactive solvents include protic solvents, such as water, and reactive organic solvents, such as alcohols.
• Reactive solvent(s) is/are also not effective in passivating lithium metal, while non-reactive solvent(s) is/are either non-reactive towards lithium metal or effectively passivating toward lithium metal, i.e., make the electrolyte/lithium-anode system kinetically stable.
• non-reactive solvents include dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, fluorine-containing carbonates, and glycol ethers.
• the term“crude” and like terms when referring to LiFSI indicate a synthesis product that contains at least LiFSI and one or more reactive solvents, such as reactive solvent(s) resulting from the synthesis and/or purification of the LiFSI or that is otherwise present in the LiFSI.
• reactive solvent(s) in LiFSI salt used in electrolytes for lithium-ion batteries and lithium-metal batteries can negatively impact the cycle performance, such as discharge capacity and capacity retention, of such batteries. Therefore, it is desirable to remove as much of the reactive solvent(s) present in the LiFSI salt as is practicable or possible.
• Such reactive solvents may also be referred to herein and in the appended claims as “solvent residue” or“solvent residues”.
• Crude LiFSI may contain further impurities, such as impurities discussed below in section II.
• anhydrous refers to having about 1% by weight of water or less, typically about 0.5% by weight of water or less, often about 0.1% by weight of water or less, more often about 0.01% by weight of water or less, and most often about 0.001% by weight of water or less.
• substantially anhydrous refers to having about 0.1% by weight of water or less, typically about 0.01% by weight of water or less, and often about 0.001% by weight of water or less.
• the term“about” when used with a corresponding numeric value refers to ⁇ 20% of the numeric value, typically ⁇ 10% of the numeric value, often ⁇ 5% of the numeric value, and most often ⁇ 2% of the numeric value. In some embodiments, the term “about” can mean the numeric value itself.
• reaction that produces the indicated and/or desired product may not necessarily result directly from the combination of the reagent(s) that was/were initially added. That is, there may be one or more intermediates that are produced in the mixture and ultimately lead to the formation of the indicated and/or desired product.
• LiFSI usually contains one or more reactive solvent residues, such as methanol, ethanol, or water, which come from a solvent source in which LiFSI is either synthesized or purified.
• reactive solvent residues are known to solvate very strongly with alkali metal salts and are hard to remove by evacuating under vacuum without heating to a high temperature.
• LiFSI is unstable to heat at high temperature in the presence of reactive solvents, and the high heat causes defluorination of the LiFSI and produces hydrogen fluoride (HF), which is a strong acid known to be corrosive.
• HF hydrogen fluoride
• R H, CH ⁇ , CH 2 CH 2l CH ⁇ CH s ⁇ 2
• protic solvents are also prone to proton reduction to yield hydrogen gas, and they are generally used for reductive electrochemistry only with electrodes such as mercury or carbon, for which proton reduction is kinetically slow.
• Protic solvents also react with lithium metal present in a lithium-based battery, especially reacting with a lithium-metal anode of a lithium-meal batter according to the following scheme to generate hydrogen gas.
• R R CHs, CH H,, CH(CH 3 ) S
• LiTFSI lithium bis(trifluoromethanesulfonyl)imide
• the present disclosure is directed to a reduced-reactive-solvent LiFSI product containing LiFSI and a relatively low level of one or more reactive solvents, such as one or more reactive solvents used in the synthesis and/or purification of crude LiFSI.
• reactive solvents that may be present in the crude LiFSI, or LiTFSI, include water, methanol, ethanol, and propanol, among others, either singly or in various combinations with one another.
• such reduced-reactive-solvent LiFSI product may be made using a reactive-solvent-reduction method of the present disclosure that can generate the reduced-reactive- solvent LiFSI product in a single pass through of one of the disclosed basic processes or in multiple passes through one or more of the disclosed basic processes.
• LiFSI salt products of the present disclosure is directed to uses of LiFSI salt products of the present disclosure.
• LiFSI salt products of the present disclosure can be used to make electrolytes that can be used in any suitable electrochemical device, such as a battery or supercapacitor, especially secondary lithium-ion batteries and secondary lithium-metal batteries.
• the present disclosure is directed to methods of purifying crude LiFSI to remove any one or more of various non-solvent impurities from the crude LiFSI.
• the term“crude LiFSI” and like terms indicate a synthesis product that contains at least LiFSI and one or more non solvent impurities, such as non-solvent impurities resulting from the synthesis of the LiFSI.
• a target impurity can be a synthesis impurity that is a byproduct of the synthesis of the LiFSI as noted above.
• crude LiFSI is commonly obtained by neutralizing hydrogen bis(fluorosulfonyl)imide (HFSI), which contains various concentrations of synthesis impurities, such as hydrogen fluoride (HF), fluorosulfuric acid (FSO 3 H), hydrogen chloride (HC1), and sulfuric acid (H 2 SO 4 ), with lithium carbonate (L1 2 CO 3 ) or lithium hydroxide (LiOH).
• HFSI hydrogen bis(fluorosulfonyl)imide
• LiFSI LiFSI
• HFSI and the impurities such as HF, FSO3H, HC1, and H2SO4
• the HFSI and the impurities are converted to the corresponding Li salt to produce LiFSI, L1 2 SO 4 , FSO 3 L1, LiF, and LiCl, respectively, by the following schemes:
• the L1 2 SO 4 , FSO 3 L1, LiF, and LiCl are target impurities (here, synthesis impurities) that are desired to be removed from the crude LiFSI.
• purification methods of the present disclosure remove one or more synthesis impurities, such as one or more of the L1 2 SO 4 , FSO 3 L1, LiF, and LiCl, and/or any other impurity having a molecular structure and properties amenable for removal by the disclosed methods, each of which is a“target impurity” in the parlance of this disclosure.
• the present disclosure is directed to a purified LiFSI product containing LiFSI and a relatively low level of one or more target impurities, such as one or more synthesis impurities, for example, L1 2 SO 4 , FSO 3 L1, LiF, and LiCl as noted above.
• target impurities such as one or more synthesis impurities, for example, L1 2 SO 4 , FSO 3 L1, LiF, and LiCl as noted above.
• target impurities such as one or more synthesis impurities, for example, L1 2 SO 4 , FSO 3 L1, LiF, and LiCl as noted above.
• target impurities such as one or more synthesis impurities, for example, L1 2 SO 4 , FSO 3 L1, LiF, and LiCl as noted above.
• such purified LiFSI product may be made using a purification method of the present disclosure that can generate the purified LiFSI product in a single pass through one of the disclosed basic processes or in multiple passes through one or more of the
• LiFSI salt products of the present disclosure is directed to uses of LiFSI salt products of the present disclosure.
• LiFSI salt products of the present disclosure can be used to make electrolytes that can be used in any suitable electrochemical device, such as a battery or supercapacitor.
• the present disclosure is directed to a method of synthesizing LiFSI using an aqueous neutralization method followed removal of impurities.
• an example LiFSI synthesis method includes neutralizing hydrogen
• HFSI bis(fluorosulfonyl) imide
• Additional steps may include removing at least a portion of the deionized water to obtain crude LiFSI and then purifying the crude LiFSI to remove at least some of the one or more synthesis impurities.
• an overall process may include using an aqueous neutralization synthesis method of this disclosure to synthesize LiFSI, with this synthesis followed by implementing, using the synthesized LiFSI, either a non-reactive-solvent purification process of this disclosure or a reactive-solvent
• an overall process may include starting with an already synthesized crude LiFSI, such as a commercially sourced, conventionally synthesized crude LiFSI, and then performing one, the other, or both, of a non-reactive-solvent purification process of this disclosure or a reactive-solvent reduction/replacement method of this disclosure.
• the present disclosure is directed to purified LiFSI products containing LiFSI made using any one of the combinations of methods described in the immediately preceding paragraph, electrolytes made using purified LiFSI salt made using any one of the combinations described in the immediately preceding paragraph, and uses of such electrolytes.
• This section addresses methods of removing and/or replacing reactive solvents in lithium sulfonimide salts, reduced-reactive-solvent lithium sulfonimide salts made thereby, and uses of such reduced-reactive-solvent lithium sulfonimide salts.
• crude LiFSI can contain one or more reactive solvents, for example, as a residue from synthesis and/or purification of the LiFSI.
• a reactive-solvent-removal method of the present disclosure can be used to reduce, including completely remove, one or more reactive solvents in the crude LiFSI. Because the removal of the reactive solvent(s) utilizes one or more non reactive solvents and at least some of the non-reactive solvent(s) remain after completing the reactive-solvent removal method, in some embodiments the method may also/alternatively be considered a solvent-replacement method, with undesirable reactive solvent(s) being replaced by non-reactive solvent(s) that do not have the negative battery performance impact of the reactive solvent(s). As described below, in some embodiments, the non-reactive solvent(s) that remain are often about 3000 ppm or less, such as in a range from about 100 ppm to about 3000 ppm.
• the reactive-solvent-removal method includes contacting the crude LiFSI with at least one first anhydrous organic solvent under an inert condition to create a solution containing the crude LiFSI and the one or more reactive solvents. Generally, this step involves replacing coordinated reactive solvent molecules bonded to the ions with desirable non reactive molecules.
• the solubility of the LiFSI in the at least one first anhydrous organic solvent is at least about 35% to about 65% at room temperature.
• the contacting of the crude LiFSI with the at least one first anhydrous organic solvent includes contacting the crude LiFSI with an amount of the at least one first anhydrous organic solvent that is in a range of about 35 wt. % to about 65 wt. % relative to the weight of the entire solution.
• the inert condition during the contacting of the LiFSI with the at least one first anhydrous organic solvent may be created using any suitable technique, such as by using argon gas and/or nitrogen gas, and/or other inert dry (i.e., water-free) gas, among others.
• the purification method may be performed at any suitable pressure, such as 1 atmosphere of pressure.
• anhydrous organic solvents from which each of the at least one first anhydrous organic solvent may be selected include, but are not necessarily limited to: organic carbonates, such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), propyl methyl carbonate (PMC), ethylene carbonate (EC), fluoroethylene carbonate (FEC), and trans butylene carbonate; nitriles, such as acetonitrile, malononitrile, and adiponitrile; alkyl acetates, such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; alkyl propionates, such as methyl propionate (MP) and ethyl propionate (EP).
• organic carbonates such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), propyl methyl carbonate (PMC),
• each of the anhydrous organic solvents selected for the at least one first anhydrous organic solvent are desired to be non-reactive with lithium metal.
• non-reactive anhydrous organic solvents include DMC, DEC, EMC, fluoroethylene carbonate, difluoroethylene carbonate, and trifluoromethyl ethyl carbonate.
• the solution After contacting the crude LiFSI, or LiTFSI, with the at least one first anhydrous organic solvent, the solution is subjected to a vacuum so as to remove the at least one first anhydrous organic solvent and the one or more reactive solvents, such as one or more of water, methanol, or ethanol, among others that may be present, so as to obtain a solid mass.
• the pressure of the vacuum may be less than about 100 Torr, less than about 10 Torr, or less than about 1 Torr, less than about 0.1 Torr, or less than about 0.01 Torr.
• the vacuum is performed at a controlled temperature, such as at a temperature in the range of about 25°C to about 40°C.
• the solid mass may then be treated with at least 100 wt. % of one or more second anhydrous organic solvents in which the LiFSI in the solid mass is insoluble to create a combination having an insoluble portion.
• This treatment may remove any coordinated or solvated solvents.
• anhydrous organic solvents from which each of the one or more second anhydrous organic solvents may be selected include, but are not necessarily limited to, dichloromethane, dichloroethane, chloroform, pentane, hexane, heptane, octane, nonane, decane, undecane, and dodecane.
• the insoluble portion is isolated from the combination in an inert atmosphere, such as provided by a dry inert gas, such as argon, nitrogen, another dry inert gas, or any combination thereof.
• the insoluble portion may be isolated in any suitable manner, such as filtration performed using any suitable methods, such as using one or more filter media, centrifuging, gravity separation, hydrocy cloning, etc.
• a dry inert gas such as argon, nitrogen, another dry inert gas, or any combination thereof.
• the insoluble portion may be isolated in any suitable manner, such as filtration performed using any suitable methods, such as using one or more filter media, centrifuging, gravity separation, hydrocy cloning, etc.
• the insoluble portion may be flushed with at least one inert gas (e.g., dry inert gas, i.e., less than 1 ppm water) so as to remove traces of the at least one second anhydrous organic solvent.
• inert gases e.g., dry inert gas, i.e., less than 1 ppm water
• examples of inert gases from which each of the at least one dry inert gas may be selected include argon and nitrogen.
• the flushed insoluble portion may be subjected to a pressure of less than about 100 Torr so as to obtain the reduced-protic-solvent LiFSI product or the reduced-protic-solvent LiTFSI product.
• the pressure may be less than about 10 Torr, or less than about 1 Torr, less than about 0.1 Torr, or less than about 0.01 Torr.
• the in-vacuo pressure is less than about 0.01 Torr.
• the vacuum is performed at a controlled temperature, such as at a temperature of less than about 40°C (e.g., in a range of about 20°C to about 40°C).
• the resulting reduced-reactive-solvent LiFSI product is typically a white free-flowing powder.
• the dried reduced-reactive-solvent LiFSI product may be stored in a dry inert container, such as a dry polytetrafluoroethylene (PTFE) container or a nickel alloy that is inert to free fluoride, at a reduced temperature, such as about 25°C or below, and within an inert gas, such as argon, to inhibit degradation of the LiFSI during storage.
• a dry inert container such as a dry polytetrafluoroethylene (PTFE) container or a nickel alloy that is inert to free fluoride
• crude LiFSI having various levels of one or more reactive solvents such as water, methanol, and/or ethanol, among others, is contacted with about 30 wt. % to about 50 wt. % of anhydrous dimethyl carbonate in which LiFSI is soluble.
• the contacting of the crude LiFSI with the DMC is followed by removal of the DMC along with reactive solvent(s) such as the water, methanol, and/or ethanol under vacuum (e.g., ⁇ about 0.01 Torr).
• the removal of the DMC results in a solid mass.
• the method may further comprise treating the obtained solid mass with anhydrous dichloromethane, in which the LiFSI is insoluble, to obtain a combination of an insoluble portion and the anhydrous dichloromethane and any other non-insoluble component(s).
• the insoluble portion e.g., powdered LiFSI
• the flushed LiFSI may be subjected to a vacuum (e.g., ⁇ 0.01 Torr) at a temperature of less than about 40°C to get a dry reduced-reactive- solvent LiFSI product, here, a free-solvent-free LiFSI product.
• a vacuum e.g., ⁇ 0.01 Torr
• the reduced-reactive-solvent LiFSI product may be free-solvent-free, practically speaking the LiFSI product will typically include at least some reactive and/or non-reactive solvent coordinated with the LiFSI.
• the dry protic- solvent-free LiFSI product may be stored in a PTFE container in inert conditions and, for example, at a temperature of less than about 25°C.
• a crude LiFSI containing one or more reactive solvents present at certain level(s) is provided.
• the reactive-solvent content of the crude LiFSI is reduced using any one of the methodologies described above.
• An end result of the reactive- solvent reduction at block 110 is a reduced- reactive-solvent LiFSI product in which the level of each reactive solvent has been reduced.
• the level of each of one or more of the reactive solvents in the reduced-reactive-solvent LiFSI product is measured using a suitable measurement procedure.
• each of the measured levels is compared to a maximum desired level for the reactive solvent(s) that is acceptable to be in the reduced-reactive- solvent LiFSI product.
• the multi-pass reactive-solvent-reduction method 100 can end at block 130.
• the reduced-reactive-solvent LiFSI product processed in the previous pass through reactive-solvent reduction at block 110 may be processed at block 110 via a loop 135.
• the anhydrous organic solvent(s) used for making the solution and/or washing the crystalized LiFSI may be the same or different as used in the previous pass through reactive-solvent reduction at block 110.
• one or more measurements of the reactive-solvent level(s) and one or more comparisons of the measured level(s) to one or more corresponding desired maximum levels can be made to determine whether the method 100 can end at block 130 or the LiFSI in the reduced-reactive-solvent LiFSI product of the most recent pass should be subjected to reactive-solvent reduction again via the loop 135.
• LiFSI lithium-based electrolyte
• Crude LiFSI would typically have reactive solvents, such as methanol, ethanol, and/or propanol from crystallization process of LiFSI. These reactive solvents are present sometimes > 3000 ppm.
• LiFSI-based electrolytes for lithium-metal batteries low, such as less than about 200 ppm, less than about 100 ppm, less than about 50 ppm ,or less than about 10 ppm.
• Using a multi-pass purification methodology of the present disclosure, such as the multi-pass reactive- solvent-reduction method 100 illustrated in FIG. 1, for crude LiFSI used to synthesize the LiFSI salt used in the electrolyte may be a useful way of achieving such low reactive solvent levels.
• multi-pass reactive-solvent reduction method 100 may be used to lower the reactive solvents (in the form of target reactive alcohols) content in an LiFSI product to below 1 ppm, starting with crude LiFSI containing 3000 ppm of alcohols as a synthesis impurity.
• a desired amount of the crude LfFSI is provided.
• the crude LiFSI is purified, i.e., the amount of undesirable alcohols is reduced, using any of the methodologies described above or exemplified below.
• the level of alcohols in the reduced-reactive-solvent LiFSI product are measured to be 1000 ppm.
• the measured level of 1000 ppm is compared against the less-than-100 ppm requirement.
• the reduced-reactive-solvent LiFSI product is processed at block 110, via loop 135, using the same or differing reactive-solvent-reduction process as used to reduce the reactive solvent level in the initial crude LiFSI.
• the starting alcohol level is 1000 ppm
• the ending impurity level in the twice reactive-solvent-reduced LiFSI product is now 500 ppm, as measured at optional block 115.
• the twice reactive-solvent-reduced LiFSI product needs to be processed again at block 110, via loop 135, with the same or different reactive-solvent- reduction method used in either of the two prior passes.
• the starting alcohol level is 500 ppm
• the ending impurity level in the thrice-reactive-solvent-reduced LiFSI product is now less than 100 ppm, as measured at optional block 115.
• the combination was stirred at room temperature for 1 hour, and the desired insoluble LiFSI product was isolated by filtration. Traces of dichloromethane were removed by flushing with dry Ar/N2 gas. The isolated LiFSI was dried at 35°C in vacuo ( ⁇ 0.1 Torr) to obtain the reduced-reactive-solvent LiFSI product in 90% yield, with ethanol at 0 ppm and water at 4 ppm.
• the resulting purified LiFSI products can have exceptionally low levels of target reactive levels of reactive solvent(s).
• the amount of reactive solvent(s) remaining in the final ultrapure LiFSI salt product is preferably less than about 100 ppm, more preferably less than about 50 ppm, and most preferably less than about 25 ppm.
• non-reactive solvent remaining in the final ultrapure LiFSI salt product is less detrimental to battery performance than reactive solvent
• the amount of non-reactive solvent(s) remaining in the final ultrapure LiFSI salt product is typically less than about 3000 ppm and more typically less than about 1000 ppm.
• the final ultrapure LiFSI salt product will typically have at least about 100 ppm of non-reactive solvent(s) but will typically have no more than about 100 ppm of reactive solvent(s).
• the level of reactive solvent(s) in the crude LiFSI prior to reactive-solvent reduction in accordance with the present disclosure may be about 500 ppm or higher, about 1000 ppm or higher, or about 2000 ppm or higher.
• purified LiFSI of the present disclosure has about 0.2% to about 0.3% DMC and water as the reactive solvent at less than 100 ppm.
• a reduced-reactive-solvent LiFSI salt product may be used to make a reduced-reactive-solvent LiFSI-based electrolyte for an electrochemical device, among other things.
• the reactive-solvent reduction of the reduced-reactive-solvent electrolyte flows from the fact that the reduced-reactive-solvent LiFSI salt product has been processed in accordance with any one or more of the methods disclosed herein.
• Such reduced-reactive-solvent electrolytes can be made using any of a variety of methods, such as by mixing a reduced-reactive-solvent LiFSI salt product (salt) of the present disclosure with one or more solvents, one or more diluents, and/or one or more additives, which solvents, diluents, and additives may be known in the art.
• the electrochemical device is a lithium-based device, such as a secondary lithium- ion battery or a secondary lithium-metal battery
• the least amount of reactive solvent(s) in the LiFSI salt used to make the electrolyte so that the reactive solvent(s) does/do not impact the performance of the battery.
• the more reactive solvent in the LiFSI salt the greater the negative impact of that reactive solvent on cycle performance, such as discharge capacity and capacity retention. Consequently, for lithium-based secondary batteries, it is desirable to remove as much of the reactive solvent(s) as practicable from the LiFSI salt used in the electrolyte for such batteries.
• the reduced-reactive- solvent LiFSI product made using techniques disclosed herein can have reactive and/or non-reactive solvent levels as indicated in the section above titled“I.C. EXAMPLE REDUCED-PROTIC- SOLVENT LiFSI PRODUCTS”.
• an important step in preparing an electrolyte for use in a lithium- based electrochemical device is to remove as much reactive solvent residue from an LiFSI salt that contains such residue, for example, from the process(es) of synthesizing and/or purifying the LiFSI salt.
• this removal process may include a replacement aspect in which one or more reactive solvents, such as one or more alcohols and water, are at least partially replaced by one or more non-reactive solvents.
• non-reactive solvent(s) used in the replacement/removal process can be selected based on it/them being beneficial to the lithium-based electrochemical device.
• a selected non-reactive solvent may be of a type that can be used as a solvent in which the LiFSI salt is dissolved so as to provide the electrolyte with the desired concentration.
• the non-reactive solvent(s) selected for the reactive-solvent removal/replacement process may be a desirable additive, separate and apart from any primary salt- dissolving function, added to particularly benefit the electrochemical device, such as an additive for promoting formation of a solid-electrolyte interphase (SEI) layer on a lithium-metal anode, among others.
• SEI solid-electrolyte interphase
• a method of preparing an LiFSI salt for use in a lithium-based electrochemical device includes providing a LiFSI salt containing one or more reactive solvent residues that would be detrimental to the functioning of the lithium-based device if such solvent residue(s) were not removed and/or replaced prior to using the LiFSI salt to prepare an electrolyte for the lithium-based device.
• the providing of the LiFSI salt may include purchasing the LiFSI salt from a commercial provider of such salt or synthesizing and/or purifying the crude LiFSI salt in house.
• This reactive- solvent-residue-containing LiFSI salt may then be processed according to any of the methodologies disclosed herein, such as the methodologies described above in the section titled“I. A.
• the method of preparing the LiFSI salt for using in a lithium-based electrochemical device may include selecting one or more non-reactive solvents for use in the reactive-solvent removal/replacement method. It is noted that the forward slash, or virgule, in“removal/replacement” and similar locations means “and/or”, that is, one, the other, or both, as is commonly understood. In some embodiments, at least one of the non-reactive solvents selected is selected on the basis of not only being non-reactive to lithium metal but also as providing a positive benefit, such as SEI layer growth promotion, in the manner of an electrolyte additive. Once the LiFSI salt has been subjected to the reactive-solvent removal/replacement processing, it may then be used to make an electrolyte for the lithium-based electrochemical device.
• FIG. 2 illustrates an electrochemical device 200 made in accordance with aspects of the present disclosure.
• the electrochemical device 200 can be, for example, a battery or a supercapacitor.
• FIG. 2 illustrates only some basic functional components of the electrochemical device 200 and that a real-world instantiation of the electrochemical device, such as a secondary battery or a supercapacitor, will typically be embodied using either a wound construction or a stacked construction.
• the electrochemical device 200 will include other components, such as electrical terminals, seal(s), thermal shutdown layer(s), and/or vent(s), among other things, that, for ease of illustration, are not shown in FIG. 2.
• the electrochemical device 200 includes spaced-apart positive and negative electrodes 204, 208, respectively, and a pair of corresponding respective current collectors 204A, 208A.
• a porous dielectric separator 212 is located between the positive and negative electrodes 204, 208 to electrically separate the positive and negative electrodes but to allow ions of a reduced-reactive-solvent LiFSI-based electrolyte 216 made in accordance with the present disclosure to flow therethrough.
• both the positive and negative electrodes 204, 208 are illustrated as being porous by way of the reduced-reactive-solvent LiFSI-based electrolyte 216 being illustrated as extending into them.
• a benefit of using a reduced-reactive-solvent LiFSI-based electrolyte of the present disclosure for reduced-reactive-solvent LiFSI-based electrolyte 216 is that reactive solvent(s) that can be in LiFSI-based electrolytes, such as protic-solvents from synthesis or purification, can be reduced to levels that are acceptable (e.g., meet one or more protic-solvent level specifications) for use in the electrochemical device 200. Examples of reduced-reactive-solvent LiFSI products (salts) and example low levels of their reactive solvent(s) that can be used to make reduced-reactive-solvent LiFSI-based electrolyte 216 are described above.
• the electrochemical device 200 includes a container 220 that contains the current collectors 204A, 208A, the positive and negative
• each of the positive and negative electrodes 204, 208 comprises a suitable material compatible with the alkali-metal ions and other constituents in the purified LiFSI-based electrolyte 216.
• Each of the current collectors 204A, 208 A may be made of any suitable electrically conducting material, such as copper or aluminum, or any combination thereof.
• the porous dielectric separator 212 may be made of any suitable porous dielectric material, such as a porous polymer, among others.
• Various battery and supercapacitor constructions that can be used for constructing the electrochemical device 200 of FIG. 2, are known in the art.
• a novelty of electrochemical device 200 lies in the high purity of the reduced-reactive-solvent LiFSI-based electrolyte 216 that has not been achieved with conventional methods of making LiFSI salts and corresponding electrolytes.
• the electrochemical device 200 may be made as follows.
• the reduced- reactive-solvent LiFSI-based electrolyte 216 may be made starting with a crude LiFSI, which is then purified using any one or more of the reactive-solvent-reduction methods described herein to create a reduced-reactive-solvent LiFSI product having suitable low levels of one or more target reactive solvents.
• This reduced-reactive-solvent LiFSI product may then be used to make the reduced- reactive-solvent LiFSI-based electrolyte 216, for example, by adding one or more solvents, one or more diluents, and/or one or more additives that enhance the performance of the electrochemical device 200.
• the reduced-reactive-solvent LiFSI-based electrolyte 216 may then be added to the electrochemical device 200, after which the container 220 may be sealed.
• This section addresses methods of removing non-solvent impurities from crude lithium sulfonimide salts, purified lithium sulfonimide salts made thereby, and uses of such purified lithium sulfonimide salts.
• LiFSI is often commercially produced using crude HFSI that is reacted with L12CO3 or LiOH, and the crude HFSI contains various synthesis impurities that result in impurities in the crude LiFSI so synthesized.
• one method of synthesizing HFSI uses urea (NH2CONH2) and
• fluorosulfonic acid FSO3H.
• Disadvantages of this process are low yield of HFSI and the isolated HFSI having a large excess of fluorosulfonic acid as an impurity. Since the boiling point (b.p.) of fluorosulfonic acid (b.p. 165.5°C) and the b.p. of HFSI (b.p. 170°C) are very close to one another, it is very difficult to separate them from one another by simple fractional distillation [1] An attempt to remove fluorosulfonic acid has been made by treating a mixture of HFSI and fluorsulfonic acid with sodium chloride where sodium chloride selectively reacts with fluorosulfonic acid to make sodium salts and HC1 byproducts. This process has suffered from low yield of purified HFSI, and the HFSI product was also contaminated with some chloride impurities (HC1 and NaCl) as impurities.
• HFSI bis(chlorosulfonyl)imide
• ASF3 arsenic trifluoride
• HCSI is treated with ASF 3 .
• Arsenic trifluoride is toxic, and because it has a high vapor pressure, it is particularly difficult to handle on an industrial scale.
• a typical reaction uses 1 :8.6 ratio of HCSI to AsF 3 .
• HFSI produced by this method was also found to be contaminated with AsF 3 and AsCF synthesis impurities, which were found to be a good source of chloride and fluoride impurities [2]
• HFSI for use in LiFSI synthesis can also be prepared by fluorinating HCSI with antimony trifluoride (SbF 3 ).
• the antimony trichloride byproduct of this reaction has both high solubility in HFSI and is sublimatable in nature; it is very difficult to separate from the desired product.
• the product of this reaction is typically contaminated with antimony trichloride, which is a good source of chloride impurities [3]
• HFSI for use in LiFSI synthesis
• HCSI high temperature
• the yield of this reaction is at most 60%, with the product contaminated with fluorosulfonic acid that is produced from the decomposition of HCSI. This by-product is difficult to remove, as the boiling point is close to the boiling point of HFSI.
• This reaction using anhydrous HF to fluorinate HSCI has achieved > 95% yield [5], but still the product is contaminated with fluorosulfonic acid, hydrogen fluoride, hydrogen chloride, and sulfuric acid as synthesis impurities.
• KFSI potassium bis(fluorosulfonyl)imide
• perchloric acid the byproduct potassium perchlorate is considered to be explosive.
• the isolated HFSI is contaminated with high level of potassium cations and some chloride impurities that are present in KFSI.
• Hydrogen bis(fluorosulfonic acid) also known as imido-bis(sulfuric acid) difluoride having the formula, FSO 2 NH-O 2 F, is a colorless liquid having a melting point (m.p.) of 17°C, a b.p.
• HFSI is a strong acid, with a pKa of 1.28 [8]
• a purification method of the present disclosure can be used to remove target impurities, such as synthesis impurities and/or other impurities, present in crude LiFSI, for example, a crude LiFSI synthesized using crude HFSI made using any one or more of the foregoing synthesis methods.
• the purification method includes contacting crude LiFSI with at least one first anhydrous organic solvent under inert conditions to create a solution containing the crude LiFSI and the one or more target impurities.
• the solubility of the LiFSI in the at least one first anhydrous organic solvent is at least about 60% at room temperature, typically in a range of about 60% to about 90%, and the solubility of each of the one or more target impurities is typically no more than about 20 parts per million (ppm) at room temperature, and often, for example, less than about 13 ppm.
• the contacting of the crude LiFSI with at least one first anhydrous organic solvent is performed using a minimum amount of the at least one first anhydrous organic solvent.
• minimum amount in the context of the at least one first anhydrous organic solvent, it is meant that the at least one first anhydrous organic solvent is provided in an amount substantially at which the LiFSI no longer continues to dissolve.
• the minimum amount of the at least one anhydrous inorganic solvent falls in a range of about 50 wt. % to about 75 wt. % of the solution.
• the contacting of the crude LiFSI with the at least one first anhydrous organic solvent is performed at a temperature lower than a temperature in a range of about 15°C to about 25°C.
• the dissolution of the crude LiFSI in the at least one first anhydrous organic solvent is an exothermic reaction. Consequently, in some embodiments, the temperature of the solution may be controlled using any suitable temperature control apparatus, such as a chiller, thermostat, circulator, etc. In some embodiments, the temperature of the solution is controlled to keep the temperature of the solution below about 25°C as the at least one anhydrous organic solvent is contacted with the crude LiFSI.
• the at least one anhydrous organic solvent may be added continuously or continually at precisely controlled rates or in precisely controlled amounts using suitable feed or dosing devices.
• the inert conditions during the contacting of the LiFSI with the at least one first anhydrous organic solvent may be created using any suitable technique, such as by using argon gas and/or nitrogen gas, and/or other inert dry (i.e., water-free) gas, among others.
• the purification method may be performed at any suitable pressure, such as 1 atmosphere of pressure.
• Examples of anhydrous organic solvents from which each of the at least one first anhydrous organic solvent may be selected include, but are not necessarily limited to, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), propyl methyl carbonate (PMC), ethylene carbonate (EC), fluoroethylene carbonate (FEC), trans butylene carbonate, acetonitrile, malononitrile, adiponitrile, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate (MP), ethyl propionate (EP), methanol, ethanol, propanol, and isopropanol.
• DMC dimethyl carbonate
• DEC diethyl carbonate
• EMC ethyl methyl carbonate
• PMC propyl methyl carbonate
• EC ethylene carbonate
• FEC fluoroethylene carbonate
• At least one second anhydrous organic solvent is added to the solution so as to precipitate that at least one target impurity.
• the at least one second anhydrous organic solvent is selected such that the LiFSI and the one or more target impurities is substantially insoluble (as noted above, it is generally desirable that target impurities should not be soluble more than 20 ppm) in the at least one second anhydrous organic solvent.
• at least one second anhydrous organic solvent is added in a minimum amount.
• the at least one second anhydrous organic solvent is provided in an amount substantially at which the one or more target impurities no longer continue to precipitate out of the solution.
• the minimum amount of the at least one anhydrous inorganic solvent falls in a range of greater than 0 wt. % to no more than about 10 wt. % of the solution.
• the at least one second anhydrous organic solvent may be added under the same temperature, pressure, and inert conditions as present during the contacting of the crude LiFSI with the at least one first anhydrous organic solvent.
• anhydrous organic solvents from which each of the at least one second anhydrous organic solvent may be selected include, but are not necessarily limited to,
• an insoluble portion of each of the one or more target impurities is separated, for example, filtered or cannulated, from the solution to produce a filtrate containing LiFSI in solution.
• the filtration may be performed using any suitable methods, such as using one or more filter media, centrifuging, gravity separation, hydrocy cloning, etc. Those skilled in the art will understand the appropriate filtration technique(s) to use in any particular instantiation of a purification method of the present disclosure.
• solvent in the filtrate is removed so as to obtain a solid mass consisting mainly of LiFSI and some reduced amount(s) of the one or more target impurities.
• the solvent removed will typically be each of the one or more first anhydrous organic solvents and the one or more second anhydrous organic solvents from previous processing.
• the solvent may be removed using any suitable techniques, such as under suitable temperature and reduced pressure conditions.
• the removing of the solvent may be performed at a pressure of about 0.5 Torr or less or about 0.1 Torr or less.
• the temperature during the removal may be, for example, about 25°C to about 40°C or less.
• the solid mass may be contacted with at least one third anhydrous organic solvent, in which LiFSI is substantially insoluble, to further remove more of the one or more target impurities by the one or more target impurities solvating with the third solvent.
• the amount of the at least one third anhydrous organic solvent used to contact the solid mass may be at least 50 wt. % of the weight of the solid mass.
• anhydrous organic solvents from which each of the at least one third anhydrous organic solvent may be selected include, but are not necessarily limited to, dichloromethane, dichloroethane, chloroform, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane.
• the LiFSI is isolated from the at least one third anhydrous organic solvent to obtain a purified LiFSI product that contains a reduced amount of each of the one or more target impurities.
• the isolating of the LiFSI from the at least one third anhydrous organic solvent may be performed using any one or more suitable techniques, such as filtering the LiFSI in solid form and/or drying the solid LiFSI, such as in vacuo.
• the in-vacuo pressure is less than about 0.1 Torr or less than about 0.01 Torr.
• the resulting purified LiFSI product is typically a white free-flowing powder.
• the dried purified LiFSI product may be stored in a dry inert container, such as a dry polytetrafluoroethylene (PTFE) container or a nickel alloy that is inert to free fluoride, at a reduced temperature, such as about 25°C or below, and within an inert gas, such as argon, to inhibit degradation of the LiFSI during storage.
• a dry inert container such as a dry polytetrafluoroethylene (PTFE) container or a nickel alloy that is inert to free fluoride
• PTFE dry polytetrafluoroethylene
• nickel alloy that is inert to free fluoride
• the following Table I illustrates an example of selecting each of a first, second, and third anhydrous organic solvent for an LiFSI purification method of the present disclosure.
• the selected first anhydrous organic solvent is dimethyl carbonate and the selected second and third anhydrous organic solvent is dichloromethane.
• the solubility of LiFSI in dimethyl carbonate is > 90%, and it is insoluble in dichloromethane.
• the solubility of target impurities such as the LiF, LiCl, and L12SO4 in this example, is less than 13 ppm in dimethyl carbonate under an anhydrous condition. Therefore, anhydrous dimethyl carbonate and anhydrous dichloromethane solvents have been chosen in this example of purifying crude LiFSI to obtain a purified LiFSI product in accordance with the present disclosure.
• crude LiFSI containing impurities reported in the Table I above may be mixed in dimethyl carbonate in about 40% to about 75% concentration at around 25°C and stirred at room temperature followed by addition of dichloromethane about 2% to about 10% to precipitate the target impurities.
• the target impurities may then be removed, for example, by filtration, and the filtrate may be concentrated to dryness.
• the obtained solid may then be treated with anhydrous dichloromethane to remove any target HF impurity, which is soluble in dichloromethane.
• LiFSI is insoluble in dichloromethane.
• Purified LiFSI may be recovered by filtration and finally dried at reduced pressure (in one example, at less than about 0.1 Torr) and at less than about 40°C to achieve a white free-flowing powder.
• the white powder was stored under argon atmosphere in a PTFE container.
• Such a multi-pass method may utilize any one or more of the foregoing methodologies in series to continually reduce the level of each of one or more target impurities initially in the crude LiFSI and then that may still be remaining in the resulting purified LiFSI product.
• An example multi-pass purification method 100 of the present disclosure is illustrated in FIG. 1.
• a crude LiFSI containing one or more target impurities present at certain level(s) is provided.
• the crude LiFSI is purified using any one of the methodologies described above.
• An end result of the purification at block 310 is a purified LiFSI product in which the level of each target impurity has been reduced.
• the level of each of one or more of the target impurities in the purified LiFSI product is measured using a suitable measurement procedure.
• each of the measured levels is compared to a maximum desired level for the corresponding target impurity that is acceptable to be in the purified LiFSI product.
• the multi-pass purification method 300 can end at block 330.
• the purified LiFSI product purified in the previous pass through purification at block 310 may be purified at block 310 via a loop 335.
• the anhydrous organic solvent(s) used for making the solution and/or washing the crystalized LiFSI may be the same or different as used in the previous pass through purification at block 310.
• one or more measurements of the target impurity level(s) and one or more comparisons of the measured level(s) to one or more corresponding desired maximum levels can be made to determine whether the method 300 can end at block 330 or the LiFSI in the purified LiFSI product of the most recent pass should be subjected to purification again via the loop 335.
• a multi-pass purification method could be useful is a lithium-based electrolyte, such as LiFSI, for a lithium-based battery.
• Crude LiFSI would typically have chloride impurities, such as LiCl from HC1 synthesis impurities in crude HFSI used to make the LiFSI, on the order of 350 ppm or more.
• chloride levels are corrosive to lithium-metal batteries. Consequently, it is desired to keep chloride levels in LiFSI- based electrolytes for lithium-metal batteries low, such as less than about 10 ppm or less than 1 ppm.
• Using a multi-pass purification methodology of the present disclosure such as the multi-pass purification method 300 illustrated in FIG. 3, for crude LiFSI used to synthesize the LiFSI salt used in the electrolyte may be a useful way of achieving such low chloride levels.
• multi-pass purification method 300 may be used to lower the chlorine (in the form of target impurity LiCl) content in an LiFSI product to below 1 ppm, starting with crude LiFSI containing 200 ppm of LiCl as a synthesis impurity.
• a desired amount of the crude HFSI is provided.
• the crude LiFSI is purified using any of the purification methodologies described above or exemplified below.
• the level of LiCl (or chlorides) in the purified LiFSI product are measured to be 100 ppm.
• the measured level of 300 ppm is compared against the less-than-1 ppm requirement.
• the purified LiFSI product is processed at block 310, via loop 335, using the same or differing purification process as used to purify the initial crude LiFSI. In this second pass, the starting target impurity level is 100 ppm, and the ending impurity level in the twice-purified LiFSI product is now 20 ppm, as measured at optional block 315.
• the starting target impurity level is 20 ppm
• the ending impurity level in the thrice-purified LiFSI product is now less than 1 ppm, as measured at optional block 315.
• FSO3 30 ppm
• CT 1 ppm
• F- 11 ppm
• SO4 2 15 ppm
• water 30 ppm.
• the resulting purified LiFSI products can have exceptionally low levels of target impurities removed by the purification method.
• a purified LiFSI product of the present disclosure in which at least one of the target impurities is LiCl can have an LiCl (Cl ) level less than or equal to 10 ppm, or less than 1 ppm.
• a purified LiFSI product of the present disclosure in which at least one of the target impurities includes LiF (F ), FSO3L1 (FSO3 ), and LiCl (Cl ) can have: F less than or equal to about 80 ppm, FSO3 less than or equal to about 100 ppm, and CT less than about 100 ppm; F less than or equal to about 40 ppm, FSO3 less than or equal to about 250 ppm, and CT less than or equal to about 20 ppm; or F less than or equal to about 200 ppm, FSO3 less than or equal to about 100 ppm, and CT less than or equal to about 30 ppm.
• each of the foregoing levels of impurities and combinations thereof can be achieved starting with a crude LiFSI having about 200 ppm or more of F , about 200 ppm or more of FSO3 , and/or about 200 ppm or more of CT.
• a purified LiFSI product of the present disclosure in which at least one of the target impurities is SO4 2 can have an SO4 2 level less than or equal to about
• each of the foregoing SO4 2 levels can be achieved starting with a crude LiFSI having about 500 ppm or more of SO4 2 .
• a useful feature of purification methods of the present disclosure is the ability to remove differing types of target impurities simultaneously with one another in each (or the only) pass through of the method.
• a purified LiFSI product may be used to make a purified LiFSI- based electrolyte for an electrochemical device, among other things.
• the purity of the purified electrolyte flows from the fact that the purified LiFSI product has been purified in accordance with any one or more of the methods disclosed herein.
• Such purified electrolytes can be made using any of a variety of methods, such as by mixing a purified LiFSI product (salt) of the present disclosure with one or more solvents, one or more diluents, and/or one or more additives, which solvents, diluents, and additives may be known in the art.
• FIG. 2 illustrates an electrochemical device 200 made in accordance with aspects of the present disclosure.
• a purified LiFSI-based electrolyte 216A made in accordance with the present disclosure may be used.
• a benefit of using a purified LiFSI-based electrolyte of the present disclosure, purified to remove non-solvent impurities, for the purified LiFSI-based electrolyte 216A is that impurities that can be in LiFSI- based electrolytes, such as synthesis impurities, can be reduced to levels that are acceptable (e.g., meet one or more impurity level specifications) for use in the electrochemical device 200.
• impurities that can be in LiFSI- based electrolytes such as synthesis impurities
• levels that are acceptable e.g., meet one or more impurity level specifications
• Examples of purified LiFSI products (salts) and example low levels of their various impurities that can be used to make the purified LiFSI-based electrolyte 216A are described above.
• the purified LiFSI-based electrolyte 216A may be made starting with a crude LiFSI, which is then purified using any one or more of the purification methods described herein to create a purified LiFSI product having suitable low levels of one or more target impurities.
• crude HFSI may first be synthesized, such as by any of the synthesis methods described above, and this crude HFSI can be used to synthesize crude LiFSI. This crude LiFSI can be purified using any one or more of the purification methods described herein to create a purified LiFSI product (salt).
• This purified LiFSI product may then be used to make the purified LiFSI-based electrolyte 216A, for example, by adding one or more solvents, one or more diluents, and/or one or more additives that enhance the performance of the electrochemical device 200.
• the purified LiFSI-based electrolyte 216A may then be added to the electrochemical device 200, after which the container 220 may be sealed.
• an LiFSI product (e.g., salt) may be obtained by first neutralizing a purified hydrogen bis(fluorosulfonyl)imide (HFSI) with one or more lithium bases, such as lithium carbonate (LECCb) or lithium hydroxide (LiOH), in deionized water may be carried out to give an aqueous solution of LiFSI.
• the insoluble impurities such as the L12SO4, LiCl, LiF, and L1FSO3 mentioned above, can be removed by filtration. The water may be removed, for example, in vacuo.
• Purified HFSI for use in this process may be obtained in any suitable manner, such as by purifying HFSI by crystallization, for example, as described in U.S. Patent Application Serial No. 16/570,131, filed on September 13, 2019, and titled“Purified Hydrogen
• a crude LiFSI product made using an aqueous neutralization process of section III.A, above can be purified to remove one or more target impurities, such as any synthesis impurities remaining after the removal of water from the synthesized LiFSI product.
• a crude LiFSI product made using an aqueous neutralization process of section III.A, above can be purified to remove and/or replace reactive solvent(s), such as water, present in the LiFSI product.
• This section briefly describes examples of purification of crude LiFSI made in accordance using an aqueous neutralization process.
• crude LfFSI which includes a crude LfFSI product made using an aqueous neutralization process described above in section III. A, can be purified to remove target impurities.
• target impurities may include any synthesis salts, for example, L12SO4, LiCl, LiF, and L1FSO3 mentioned above in section III.A, that may remain after filtration of such insoluble salts and removal of water.
• the resulting LiFSI product here,“crude LiFSI” for the context of purification in accordance with section II. A, above
• the resulting LiFSI product here,“crude LiFSI” for the context of purification in accordance with section II. A, above
• the resulting purified LiFSI product will have reduced levels of the impurity(ies) targeted.
• Experimental examples of such purification and corresponding target impurity levels are described below in Examples 2, 5, and 7 in, respectively, sections III.C.2, III.C.5, and III.C.7.
• the solvent(s) used in the purification process may be one or more of the solvent(s) used in the final electrolyte solution. In this manner, any solvent(s) remaining from the purification process will become part of the final electrolyte-solution solvent(s).
• crude LiFSI which includes a crude LiFSI product made using an aqueous neutralization process described above in section III.A, can be purified to remove/replace one or more reactive solvents.
• reactive solvents may include any remaining water not removed in the water-removal step mentioned above in section III.A.
• one or more reactive solvents targeted for removal and/or replacement by one or more non-reactive solvents may be present after purification to remove non-reactive-solvent impurities as described above in sections III.B.1 and II. A.
• the resulting LiFSI product (here,“crude LiFSI” for the context of purification in accordance with section I.A, above) can be subjected to the purification described above in section I.A.
• the resulting purified LiFSI product (here,“crude LiFSF’ for the context of purification in accordance with section I.A, above) can be subjected to the purification described above in section I.A.
• the resulting purified LiFSI product will have reduced levels of the reactive solvent(s) targeted.
• Experimental examples of such purification and corresponding target impurity levels are described below in Examples 3 of sections III.C.3.
• the solvent(s) used in the reactive-solvent-removal/replacement process may be one or more of the solvent(s) used in the final electrolyte solution. In this manner, any solvent(s) remaining from the removal/replacement process will become part of the final electrolyte-solution solvent(s).
• the crude LiFSI so obtained may be purified to remove one or more target impurities, such as synthesis impurities and/or other impurities, present in crude LiFSI.
• the crude LiFSI may be mixed with minimum amount (e.g., about 50% to about 70% by weight) of one or more first anhydrous organic solvents in which LiFSI is soluble so as to leave impurities such as L12SO4, LiCl, LiF, and L1FSO3 further insoluble.
• Anhydrous organic solvents that can be used for this include dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), propyl methyl carbonate (PMC), ethylene carbonate (EC), fluoroethylene carbonate (FEC), trans butylene carbonate, acetonitrile, malononitrile, adiponitrile, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate (MP), and ethyl propionate (EP).
• DMC dimethyl carbonate
• DEC diethyl carbonate
• EMC ethyl methyl carbonate
• PMC propyl methyl carbonate
• EC ethylene carbonate
• FEC fluoroethylene carbonate
• trans butylene carbonate acetonitrile, malononitrile, adiponitrile, methyl acetate, ethyl acetate, propyl
• one or more second anhydrous organic solvents in which LiFSI is insoluble is/are added (e.g., in an amount of about 2% to 10%, by weight).
• Organic solvents that can be used for this include dichloromethane, dichloroethane, chloroform, pentane, hexane, heptane, octane, nonane, decane, undecane, and dodecane.
• impurities remain precipitated after the addition of the one or more second anhydrous organic solvents and may be removed by filtration.
• the filtrate may be collected and the solvent(s) removed therefrom to obtain a solid.
• the solvent(s) is/are removed at controlled temperature (e.g., ⁇ about 40°C) in vacuo (e.g., ⁇ about 0.1 Torr) to obtain the solid.
• the obtained solid may then be treated with at least one third anhydrous organic solvent in which LiFSI is insoluble.
• Organic solvents that can be used for this include
• the precipitated LiFSI salt product may then be isolated by filtration under an inert environment, (e.g., argon gas) and dried, for example, at ⁇ about 40°C in vacuo (e.g., ⁇ about 0.1 Torr).
• an inert environment e.g., argon gas
• ⁇ about 40°C in vacuo e.g., ⁇ about 0.1 Torr
• Table II provides a detailed example of impurities and their solubility in dimethyl carbonate and dichloromethane.
• solubility of LiFSI in dimethyl carbonate is > 90%, and it is insoluble in dichloromethane.
• solubility of impurities such as LiF, LiCl, and L12SO4 is less than 13 ppm in dimethyl carbonate under anhydrous condition.
• dichloromethane solvents are chosen in one example for the process of purifying the crude LiFSI made using the aqueous-based neutralization process described above.
• the crude LiFSI containing impurities reported in Table II, above was mixed in dimethyl carbonate in 50% to 75% concentration at around 25°C (here, room temperature) and stirred at room temperature followed by addition of dichloromethane about 2% to about 10%, by weight, to precipitate impurities.
• the impurities were removed by filtration, and the filtrate was concentrated to dryness.
• the resulting dry solid was treated with anhydrous dichloromethane to remove any HF impurities, which are soluble in dichloromethane while LiFSI is insoluble in dichloromethane.
• An ultrapure LiFSI salt product was recovered by filtration and finally dried at reduced pressure (e.g., ⁇ about 0.1 Torr) and at a temperature of ⁇ about 40°C to achieve a white free- flowing powder, which may optionally be stored in dry polytetrafluoroethylene (PTFE) container.
• reduced pressure e.g., ⁇ about 0.1 Torr
• a temperature of ⁇ about 40°C e.g., a white free- flowing powder, which may optionally be stored in dry polytetrafluoroethylene (PTFE) container.
• PTFE dry polytetrafluoroethylene
• the present disclosure describes a process for producing ultrapure lithium bis(fluorosulfonyl)imide (LiFSI) for lithium metal anode battery applications.
• the process comprises neutralizing a purified hydrogen bis(fluorosulfonyl)imide (HFSI) with lithium bases, such as, for example, lithium carbonate (L12CO3) or lithium hydroxide (LiOH), in less than about 40% deionized water below about 25°C.
• the insoluble impurities, such as L12SO4, LiCl, LiF, and L1FSO3 may be removed by filtration.
• the water may be removed in vacuo (e.g., ⁇ about 0.1 Torr) at a suitable temperature, such as below about 35°C.
• the obtained crude LiFSI may be mixed with a minimum amount (e.g., 50% to 70% by weight) of anhydrous organic solvent (such as, for example, dimethyl carbonate (DMC) or ethyl methyl carbonate (EMC)) in which LiFSI is soluble so as to leave impurities such as LiCl, LiF, L12SO4, and/or L1FSO3, further insoluble.
• anhydrous organic solvent such as, for example, dimethyl carbonate (DMC) or ethyl methyl carbonate (EMC)
• LiFSI is soluble so as to leave impurities such as LiCl, LiF, L12SO4, and/or L1FSO3, further insoluble.
• the temperature of the solution is maintained at less than about 25°C.
• the solution may then be filtered in inert atmosphere to remove impurities.
• the process may further comprise removing the organic solvents from the filtrate to get solid mass and treating the solid with organic solvent (e.g., dichloromethane) wherein the lithium bis(fluorosulfonyl)imide is insoluble.
• organic solvent e.g., dichloromethane
• the insoluble LiFSI may be isolated by filtration in inert atmosphere and flushing the traces of organic solvent with dry argon and/or nitrogen gas.
• the obtained LiFSI may be evacuated (e.g., at less than about 0.1 Torr) at a suitable temperature (e.g., less than about 35°C) for a suitable period of time (e.g., at least 24 hours) to achieve an ultrapure anhydrous LiFSI salt product as white free-flowing powder, which may optionally be stored in dry polytetrafluoroethylene (PTFE) container.
• a suitable temperature e.g., less than about 35°C
• a suitable period of time e.g., at least 24 hours
• an LiFSI salt product synthesized by the disclosed aqueous neutralization method, purified to remove non-reactive-solvent impurities, and purified to remove/replace reactive solvent(s) may be made into an electrolyte solution and used in a lithium- metal battery, i.e., a battery having a lithium-metal anode.
• a lithium- metal battery i.e., a battery having a lithium-metal anode.
• this“ultrapure” LiFSI salt product and electrolytes made therewith have shown much better cycle life compared to LiFSI from commercial sources such as Nippon Shokubai Co., Ltd. (Japan), Shenzhen Capchem Co., Ltd. (China), Shang Hai Shengzhan Chemifish Co., Ltd. (China), and Oakwood Products, Inc. (USA).
• the production process of ultrapure LiFSI can be a continuous process starting from the beginning neutralization to the end of producing the ultrapure LiFSI product.
• Example 2 Treating LiFSI with Dimethyl Carbonate:
• the LiFSI obtained in Example 2 was used in this Example 3.
• 200 g LiFSI obtained in Example 2, above, was taken in the glove box having water reading ⁇ 1 ppm and transfer in a 1 L dry flask. The flask was taken out and cooled with water bath ⁇ 15°C.
• the LiFSI was mixed with 100 g of anhydrous dimethyl carbonate containing water ⁇ 5 ppm.
• the insoluble impurities were removed by filtration under argon and filtrate was collected in a 1 L flask.
• the filtrate was concentrated at reduced pressure ⁇ 0.1 Torr to get a solid.
• the water content was 1.3 ppm, as analyzed by Karl Fisher. Based on proton NMR, it has 0.2% dimethyl carbonate. Dimethyl carbonate was used in a test electrolyte formulation, as it is non-reactive with lithium metal within an electrochemical device. This salt electrolyte formulation was used in lithium metal battery testing.
• FIGS. 4A and 4B show, respectively, discharge capacity versus cycle number and capacity retention versus cycle number for two non-aqueous electrolytes having the same concentrations and identical chemistries, except that one of the electrolytes was made using an ultrapure LiFSI salt product made using an aqueous-neutralization-synthesis method of section III of the present disclosure (upper lines in each of FIGS. 4A and 4B;“SES LiFSI”) and the other electrolyte was made using an LiFSI salt sourced from Capchem (lower lines in each of FIGS. 4A and 4B;“CapChem LiFSI”).
• the battery cells used in experiments that resulted in the graphs of FIGS. 4A and 4B were pouch cells having 3 layers of cathode and 4 layers of anode.
• the electrolytes were each composed of 2.0 mole LiFSI in 1 liter of a solvent mixture. Except for the source of the LiFSI salt, all other cell design factors and testing conditions were the same.
• the cells were cycled under 0.2C rate charging and 1.0C rate discharging.
• FIGS. 4A and 4B show, cells with LiFSI from both sources delivered the same capacity in early cycles.
• the cell with electrolyte made using the ultrapure LiFSI salt of the present disclosure exhibited better capacity retention than the cell with the Capchem LiFSI salt after about 100 cycles. This data indicate the stability advantage of ultrapure LiFSI salt over the Capchem LiSFI salt under long term cycling conditions with lithium metal anode rechargeable batteries.
• an ultrapure LiFSI salt product made in accordance with the processes described above can be particularly beneficial to lithium-metal batteries having lithium-metal anodes.
• it is important to select the appropriate anhydrous organic solvents for the processing since at least some solvent may remain in the ultrapure LiFSI product and, if reactive to lithium metal, may interfere with the performance of the lithium-metal batteries in which the ultrapure LiFSI product is used as an electrolyte.
• the solvents selected should be solvents known to be non reactive to lithium metal.
• any solvent that may remain in the final dry solid ultrapure LiFSI salt product e.g., by coordination with the LiFSI or otherwise, is non-reactive to lithium- metal and therefore less likely to be detrimental to the performance of the lithium-metal battery in which the ultrapure LiFSI salt product is used.
• the term“non-reactive” when used to modify“solvent” or“solvents” shall mean that the solvent(s) is/are non-reactive to lithium metal.
• the term“reactive” used herein and in the appended claims to modify“solvent” or“solvents” shall mean that the solvent(s) is/are reactive to lithium metal.
• “reactive” in this context refers to the magnitude of the reduction potential of lithium metal relative to the solvent(s). Reactive solvent is also not effective in passivating lithium metal, while non reactive solvent is either non-reactive towards lithium metal or effectively passivates the lithium metal, i.e., is kinetically stable.
• the amount of reactive solvent(s) remaining in the final ultrapure LiFSI salt product is preferably less than about 500 ppm, more preferably less than about 100 ppm, and most preferably less than about 50 ppm.
• non-reactive solvent remaining in the final LiFSI salt product may be less detrimental to battery performance than the removed reactive solvent.
• the amount of non-reactive solvent(s) remaining in the final LiFSI salt product is preferably less than about 3000 ppm, more preferably less than about 2000 ppm, and most preferably less than about 500 ppm.
• non-reactive solvent remaining in the final LiFSI salt product may be beneficial to battery performance, such as when the non-reactive solvent(s) used is/are intentionally selected to provide one or more benefits to the cathode-electrolyte-anode system, such as improved SEI formation and/or improved ion availability within the electrolyte.
• additional amounts of the non-reactive solvent(s) used during purification and/or reactive-solvent removal/replacement may be added to make the final electrolyte.
• the amount of non-reactive solvent remaining can be greater than 2000 ppm or greater than 3000 ppm.
• the final LiFSI salt product will typically have at least about 100 ppm of non- reactive solvent(s) but will typically have no more than about 100 ppm of reactive solvent(s).
• non-reactive solvents examples include hexane, hydrocarbons, toluene, xylene, aromatic solvents, esters, and nitriles.
• FIG. 2 illustrates an electrochemical device 200 made in accordance with aspects of the present disclosure.
• an ultrapure LiFSI-based electrolyte 216 instead of reduced- reactive-solvent LiFSI-based electrolyte 216 described above, an ultrapure LiFSI-based
• electrolyte 216B made in accordance with the section III may be used.
• a benefit of using an ultrapure LiFSI-based electrolyte of the present disclosure for the purified LiFSI-based electrolyte 216B is that impurities that can be in LiFSI-based electrolytes, such as synthesis impurities and reactive-solvent(s), can be reduced to levels that are acceptable (e.g., meet one or more impurity level specifications) for use in the electrochemical device 200.
• impurities that can be in LiFSI-based electrolytes such as synthesis impurities and reactive-solvent(s)
• levels that are acceptable e.g., meet one or more impurity level specifications
• Examples of ultrapure LiFSI products (salts) and example low levels of their various impurities that can be used to make the purified LiFSI-based electrolyte 216B are described above.
• This ultrapure LiFSI product may then be used to make the ultrapure LiFSI-based electrolyte 216B, for example, by adding one or more solvents, one or more diluents, and/or one or more additives that enhance the performance of the electrochemical device 200.
• the ultrapure LiFSI-based electrolyte 216B may then be added to the electrochemical device 200, after which the container 220 may be sealed.
• the purification methodologies disclosed herein may be augmented with the selecting of one or more solvents known to be non-reactive with respect to lithium metal for the appropriate step(s) of the methodology being used to perform the purification.
• the present disclosure is directed to a method of creating a reduced- reactive-solvent lithium bis(fluorosulfonyl) imide (LiFSI) product, the method comprising:
• providing the first crude LiFSI includes: providing a second crude LiFSI containing LiFSI and one or more target impurities;
• the second crude LiFSI has a solubility in the at least one third anhydrous organic solvent of at least about 50% at room temperature
• each of the one or more target impurities has a solubility in the at least one third anhydrous organic solvent that is no more than about 20 parts per million (ppm) at room
• contacting the second crude LiFSI with at least one third anhydrous organic solvent includes contacting the second crude LiFSI with a minimum amount of the at least one third anhydrous organic solvent.
• the minimum amount of the at least one third anhydrous organic solvent is about 40 wt. % to about 75 wt. % of the solution.
• adding at least one fourth anhydrous organic solvent to the solution includes adding the at least one fourth anhydrous organic solvent in an amount that is no more than about 10 wt. % of the solution.
• the contacting of the second crude LiFSI with the at least one third anhydrous organic solvent is performed at a temperature below about 25°C.
• the inert atmosphere comprises argon gas.
• isolating the LiFSI includes filtering the LiFSI in solid form from the at least one fifth anhydrous organic solvent.
• isolating the LiFSI includes drying the solid LiFSI in vacuo.
• drying the solid LiFSI in vacuo includes drying the solid LiFSI at a pressure of about 0.1 Torr or less.
• the one or more target impurities includes one or more target impurities from the group consisting of lithium chloride (LiCl), lithium fluoride (LiF), lithium sulfate (L12SO4), lithium fluorosulfate (L1SO3), hydrogen fluoride (HF), and fluorosulfonic acid (FSO3H).
• the one or more target impurities include lithium sulfate (L12SO4); and filtering an insoluble portion of each of the one or more target impurities includes simultaneously filtering an insoluble portion of the LESCE.
• the at least one third anhydrous organic solvent includes at least one solvent selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), propyl methyl carbonate (PMC), ethylene carbonate (EC), fluoroethylene carbonate (FEC), trans butylene carbonate, acetonitrile, malononitrile, adiponitrile, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate (MP), ethyl propionate (EP), methanol, ethanol, propanol, isopropanol.
• DMC dimethyl carbonate
• DEC diethyl carbonate
• EMC ethyl methyl carbonate
• PMC propyl methyl carbonate
• EC ethylene carbonate
• FEC fluoroethylene carbonate
• trans butylene carbonate acetonitrile, malononit
• contacting the second crude LiFSI with at least one third anhydrous organic solvent includes contacting the second crude LiFSI with an amount of the at least one third anhydrous organic solvent that is about 50 wt. % to about 75 wt. % of the solution.
• adding at least one fourth anhydrous organic solvent to the solution includes adding the at least one fourth anhydrous organic solvent in an amount that is no more than about 10 wt. % of the solution.
• the at least one fourth anhydrous organic solvent includes at least one solvent selected from the group consisting of dichloromethane, dichloroethane, chloroform, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane.
• adding at least one fourth anhydrous organic solvent to the solution includes adding the at least one fourth anhydrous organic solvent in an amount that is no more than about 10 wt. % of the solution.
• the at least one fifth anhydrous organic solvent includes at least one solvent selected from the group consisting of dichloromethane, dichloroethane, chloroform, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane.
• the at least one fourth anhydrous organic solvent includes at least one solvent selected from the group consisting of dichloromethane, dichloroethane, chloroform, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane.
• the at least one fifth anhydrous organic solvent includes at least one solvent selected from the group consisting of dichloromethane, dichloroethane, chloroform, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane.
• the one or more target impurities are byproducts of a process of synthesizing the LiFSI in the second crude LiFSI.
• the first crude LiFSI contains about 500 parts per million (ppm) or less of FSCbLi, about 100 ppm or less of LiCl, and about 150 ppm or less of LiF.
• providing the second crude LiFSI includes synthesizing the second crude LiFSI using an aqueous-based neutralization process.
• providing the first crude LiFSI includes synthesizing the first crude LiFSI using an aqueous-based neutralization process.
• the reduced-reactive-solvent LiFSI product is a salt for an electrolyte for a lithium-metal battery and the method further comprises selecting each of the at least one first anhydrous organic solvents to enhance performance of the lithium-metal battery.
• the method further comprising selecting each of the at least one second anhydrous organic solvent to enhance performance of the lithium-metal battery.
• the reduced-reactive-solvent LiFSI product is a salt for an electrolyte containing an additive solvent, wherein at least one of the at least first anhydrous solvents is the same as the additive solvent.
• the present disclosure is directed to a method of making an
• electrochemical device the method comprising: processing lithium bis(fluorosulfonyl)imide (LiFSI) salt using any of the methods recited herein, to create a purified LiFSI salt; formulating an electrolyte using the purified LiFSI salt; providing an electrochemical device structure that includes a positive electrode, a negative electrode spaced from the positive electrode, and a volume that extends between the positive and negative electrodes and, when the electrolyte is present therein allows ions in the electrolyte to move between the positive and negative electrodes; and adding the electrolyte to the volume.
• LiFSI lithium bis(fluorosulfonyl)imide
• the electrochemical device is an electrochemical battery
• the electrochemical device structure further includes a separator located within the volume.
• the electrochemical battery is a lithium-ion battery.
• the electrochemical battery is a lithium-metal battery.
• the electrochemical devices is a supercapacitor.
• the present disclosure is directed to an electrochemical device, comprising: a positive electrode; a negative electrode spaced from the positive electrode; a porous dielectric separator located between the positive and negative electrodes; and an electrolyte contained within at least the porous dielectric separator, the electrolyte made using an LiFSI salt made using of any one of the methods recited herein.
• the electrochemical device is a lithium battery.
• the electrochemical device is a lithium-metal secondary battery.
• the electrochemical device wherein the electrochemical device is a supercapacitor.
• the conjunctive phrases in the foregoing examples in which the conjunctive list consists of X, Y, and Z shall each encompass: one or more of X; one or more of Y; one or more of Z; one or more of X and one or more of Y; one or more of Y and one or more of Z; one or more of X and one or more of Z; and one or more of X, one or more of Y and one or more of Z.

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