Localized high salt electrolyte

Abstract

The battery includes a cathode having a disordered rock-salt structure and an electrolyte. The electrolyte includes a solvating solvent and a lithium salt that is soluble in the solvating solvent. The electrolyte includes a diluent that is miscible with the solvating solvent. The lithium salt is at least five times more soluble in the solvating solvent than in the diluent, and the solvating solvent and diluent are present in the battery at a diluent / solvating solvent ratio of 0.1 to less than 3.0.

Description

[Technical Field]

[0001] The present disclosure relates to liquid localized high salt concentration electrolytes for batteries. [Background technology]

[0002] New batteries utilize cathodes and lithium metal anodes to improve battery performance. During battery cycling, lithium stripping and plating at the anode can lead to the formation of high-surface-area lithium and lithium dendrites. This effect can lead to battery capacity fade. To help stabilize the battery, electrolytes with high salt concentrations have been formulated and have been shown to improve cycling performance. In these types of high-concentration electrolytes, all of the solvent molecules participate in solvating ions from the salt, leaving no free solvent molecules. However, high-salt electrolytes can result in high viscosity, limiting their application in batteries.

[0003] Recently, in an attempt to improve upon some of the drawbacks of high-salt electrolytes, diluent solvents have been added to the high-salt electrolytes to form localized high-salt electrolytes with desirable viscosities while retaining some of the performance improvements of the high-salt electrolytes (see, for example, U.S. Patent Nos. 5,629,992 and 5,729,992).

[0004] In electrolytes containing a diluent, a lithium salt, and a solvating solvent, the lithium salt may be consumed as the battery cycles, leading to the destruction of the solvation structure. As the solvation structure is destroyed, the solvating solvent may react at the electrodes. Therefore, new combinations of diluent, solvating solvent, and salt are needed that extend the number of cycles before the electrolyte begins to decompose.

[0005] Furthermore, current cathodes may lack the energy density required by industrial needs and may have harmful environmental impacts due to the use of undesirable metals such as nickel and cobalt. Therefore, new environmentally friendly high energy density cathodes and electrolytes that function with these cathodes to create batteries with high initial discharge capacities and high capacity retention are needed. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent No. 11,094,966 [Patent Document 2] U.S. Patent No. 10,367,232 Summary of the Invention

[0007] The present disclosure provides batteries that include novel electrolyte formulations.

[0008] The battery may include an anode, a cathode, and / or a separator. In some examples, the cathode has a disordered rock salt structure.

[0009] In one aspect, the present disclosure provides a battery including a cathode comprising a disordered rock-salt structure and an electrolyte. The electrolyte includes a solvating solvent and a lithium salt soluble in the solvating solvent. The electrolyte includes a diluent miscible with the solvating solvent. The lithium salt is at least five times more soluble in the solvating solvent than in the diluent, and the solvating solvent and diluent are present in the battery at a diluent / solvating solvent ratio of 0.1 to less than 3.0.

[0010] In some embodiments, the diluent may have a miscibility point in the solvating solvent, and the salt may have a saturation point in the solvating solvent, such that the saturation point of the salt in the solvating solvent is at least 5 times higher than the miscibility point of the diluent in the solvating solvent. The diluent and solvating solvent may be immiscible at a diluent / solvating solvent molar ratio of 5 or greater. The diluent and solvating solvent may be present in a molar ratio of 1.0 to 3.0. The lithium salt, the solvating solvent, and the diluent combination may be present in a molar ratio of 1:2 or greater. The lithium salt may be present in the solvating solvent or the solvating solvent / diluent combination at a concentration of about 0.5 M or greater up to the saturation point. The solvating solvent may include one or more of a dialkoxyalkane, a dialkyl glycol ether, a disubstituted ester, a disubstituted carbonate, a trisubstituted phosphate, a disubstituted sulfone, and a tetrasubstituted silane. The solvating solvent may include a disubstituted carbonate.

[0011] In another embodiment, a battery includes a cathode and an electrolyte. The electrolyte can include a solvating solvent and a lithium salt, including a first lithium salt and a second lithium salt, both of which are soluble in the solvating solvent. The second lithium salt can be present at a concentration that can be equal to or less than the concentration of the first lithium salt. The electrolyte includes a diluent that is miscible with the solvating solvent at the molar concentration used to make the electrolyte. The lithium salt can be at least five times more soluble in the solvating solvent than in the diluent, and the solvating solvent and diluent are typically present in the battery at a diluent / solvating solvent molar ratio of 0.1 to less than 3.0.

[0012] In some embodiments, the first lithium salt and the second lithium salt may be present in a molar ratio of 1 or greater or 2 or greater within the solvating solvent or solvating solvent / diluent combination below their saturation points. The solvating solvent and diluent may be immiscible at a diluent / solvating solvent molar ratio of 5.0 or greater. The concentrations of the first lithium salt and the second lithium salt may be within about 20% of their respective phase separation (saturation points) in the electrolyte. The battery may include an anode comprising one or more of graphite, lithium, a lithium alloy, silicon, and a silicon alloy. The cathode may be chargeable to a voltage of 4.45V or greater. The cathode may include a disordered rock-salt structure. The first lithium salt and the second lithium salt (total salts) may be present in a molar ratio of about 1:2.5 to about 1:5 relative to the solvating solvent and diluent combination. The first lithium salt and the second lithium salt may be present in a molar ratio of about 9:1 to about 1:1.

[0013] In some embodiments, the first lithium salt or the second lithium salt can include one or more of lithium bis(oxalato)borate (LiBOB), lithium bis(pentafluoroethylsulfonyl)imide (Li-BETI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF), lithium trifluoromethanesulfonate (LiTriflate), lithium hexafluoroarsenate (LiAsF), lithium bis(trifluoromethanesulfonimide) (LiTFSI), and lithium hexafluorophosphate (LiPF), lithium nitrate (LiNO), LiN(SOCF), LiN(SOF), LiCFSO, LiClO, lithium difluorooxalatoborate anion (LiDFOB), LiI, LiBr, LiCl, LiOH, and LiSO. The battery can have a capacity retention of 80 percent for about 100 cycles or more. The battery may have a capacity of about 180 mAh / g or greater.The diluent may be 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether; bis(2,2,2-trifluoroethyl) ether, hexafluoroisopropyl methyl ether; 1,1,2,2-tetrafluoroethyl ethyl ether; 1H,1H,5H-octafluoropentyl 1,1,2,2-tetrafluoroethyl ether; 1,1,2,2-tetrafluoroethyl ether, 1,2-(1,1,2,2-tetrafluoroethyl ether) fluoroethoxy)ethane; 1,3-(1,1,2,2-tetrafluoroethoxy)propane (TFEP); 1,1,2,3,3,3-hexafluoropropyl 2,2,2-trifluoroethyl ether; n-butyl 1,1,2,2-tetrafluoroethyl ether; 1H,1H,2'H,3H-decafluorodipropyl ether; 1,1,2,3,3,3-hexafluoropropyl ethyl ether; 1,1,1-trifluoro-2-[1-(2,2, 2-trifluoroethoxy)ethoxy]ethane; 1H,1H,2'H-perfluorodipropyl ether, 1,1,2,2-tetrafluoroethyl isobutyl ether; 1,1,1,2,2,3,4,5,5,5-decafluoro-2-methoxy-4-(trifluoromethyl)pentane; 1-(ethoxy)nonafluorobutane having a mixture of n- and iso-butyl isomers; 2-(trifluoromethyl)-3-ethoxydodecafluorohexane; 3-methoxyperfluoro(2-methylpentane); heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether; 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether; methoxynonafluorobutane; ethoxynonafluorobutane; tris(2,2,2-trifluoroethyl)orthoformate; and di(2,2,2-trifluoroethyl)carbonate. The solvating solvent may include a dialkoxyalkane, a dialkyl glycol ether, a disubstituted ester, a disubstituted carbonate, a trisubstituted phosphate, a disubstituted sulfone, a tetrasubstituted silane, or any combination thereof.

[0014] In another aspect, the present disclosure provides a method of forming an electrolyte, the method comprising dissolving a first lithium salt and a second lithium salt in a solvating solvent to form a solvating solvent-lithium salt solution, and dissolving a diluent in the solvating solvent-lithium salt solution, the method comprising further dissolving more of the first lithium salt or the second lithium salt to a concentration that exceeds the amount of lithium salt soluble in the solvating solvent present to form the electrolyte.

[0015] In some embodiments, the first lithium salt and / or the second lithium salt can be present in the electrolyte below the saturation point of the salt in the electrolyte. The first lithium salt and / or the second lithium salt can have different saturation points in the solvating solvent-lithium solution and the electrolyte.

[0016] In another aspect, the present disclosure provides an electrolyte composed of a solvating solvent, a diluent, and lithium salts, including a first lithium salt and a second lithium salt. The electrolyte is a solution having a saturation point. The solvating solvent also has a saturation point. The lithium salt can be at least five times more soluble in the solvating solvent. The first lithium salt and / or the second lithium salt can be present in the electrolyte in an amount below their saturation point and above the saturation point of the solvating solvent. The first lithium salt and / or the second lithium salt can have different saturation points in the electrolyte and the solvating solvent.

[0017] The present disclosure has discovered that adding a second lithium salt within a localized high-salt electrolyte can provide a battery with increased capacity retention. The first and second lithium salts can have different anion structures and therefore can be consumed at different rates. This can be advantageous because the composition and structure of the localized high-salt electrolyte can be retained over a longer cycle life, as measured by cycle retention at 80 percent of maximum discharge capacity.

[0018] Furthermore, the present disclosure has identified that the use of a localized, high-concentration electrolyte with a disordered rock-salt cathode can provide a battery with high charge capacity and capacity retention. The disordered rock-salt cathode can have a high energy density and can eliminate some expensive metals used in other batteries, such as nickel and cobalt. Nickel- and cobalt-free batteries may be more desirable because they are more environmentally friendly and have lower manufacturing costs. Therefore, a cheaper, more environmentally friendly disordered rock-salt cathode with similar or superior properties to conventional cathodes, such as nickel- or cobalt-based cathodes, can be used in the cathode. [Brief explanation of the drawings]

[0019] [Figure 1A] 1 shows the discharge capacity and capacity retention of various solvation solvents used in disordered rock salt cathodes. [Figure 1B] 1 shows the discharge capacity and capacity retention of various solvation solvents used in disordered rock salt cathodes. [Figure 2A] 1 shows the discharge capacity and capacity retention of a single lithium salt compared to a dual lithium salt electrolyte. [Figure 2B] 1 shows the discharge capacity and capacity retention of a single lithium salt compared to a dual lithium salt electrolyte. [Figure 3A] 1 shows the discharge capacity and capacity retention of various diluents used in a random rock salt cathode. [Figure 3B] 1 shows the discharge capacity and capacity retention of various diluents used in a random rock salt cathode. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following definitions apply to some of the aspects described with respect to some embodiments of the present invention. These definitions may be expanded upon herein as well. Each term is further explained and exemplified throughout the description, drawings, and examples. Any interpretation of a term in this description shall take into account the full description, drawings, and examples presented herein.

[0021] Definitions of certain functional groups and chemical terms are described in more detail below. For purposes of the present invention, chemical elements are defined as defined in the Periodic Table of the Elements, CAS version, Handbook of Chemistry and Physics, 75 th Ed., and specific functional groups are generally defined herein. Further, general principles of organic chemistry, and specific functional moieties and reactivities, are described in Organic Chemistry, Thomas Sorrell, University Science Books, Sausalito, 1999, Smith and March's Advanced Organic Chemistry, 5th Edition, John Wiley & Sons, Inc., New York, 2001, Larock, Comprehensive Organic Transformations, VCH Publishers Inc., New York, 1989, and Carruthers, Some Modern Methods of Organic Synthesis, 3rd Edition, Cambridge University Press, Cambridge, 1987, the entire contents of each of which are incorporated herein by reference.

[0022] As used herein, the terms "halo" and "halogen" refer to an atom selected from fluorine (fluoro, -F), chlorine (chloro, -Cl), bromine (bromo, -Br), and iodine (iodo, -I). As used herein, the term "aliphatic group" refers to a hydrocarbon moiety that may be straight-chain (i.e., unbranched), branched, or cyclic (including fused, bridged, and spiro-fused polycyclics) and may be fully saturated or contain one or more units of unsaturation, but is not aromatic. An aliphatic group may contain 1 to 40 carbon atoms, 1 to 20 carbon atoms, 2 to 20 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, 1 to 6 carbon atoms, 1 to 5 carbon atoms, 1 to 4 carbon atoms, 1 to 3 carbon atoms, or 1 or 2 carbon atoms. Exemplary aliphatic groups include, but are not limited to, straight-chain or branched alkyl and alkenyl groups, and hybrids thereof, such as (cycloalkyl)alkyl, (cycloalkenyl)alkyl, or (cycloalkyl)alkenyl. Aliphatic groups can be unsubstituted or substituted. Substituted means that one or more C or H atoms are replaced with oxygen, boron, sulfur, nitrogen, phosphorus, or halogen. Typically, 1 to 6 carbon atoms can be independently replaced with the foregoing, particularly oxygen, sulfur, or nitrogen. Aliphatic groups can have one or more "halo" and "halogen" atoms selected from fluorine (fluoro, -F), chlorine (chloro, -Cl), bromine (bromo, -Br), and iodine (iodo, -I).

[0023] As used herein, "phase" means one or more compounds that are physically distinct and mechanically separable from another set of compounds.

[0024] "Miscible" means that two or more compounds form a solution when they come into contact. Compounds can be completely miscible at any molar ratio (mol / mol), but often compounds are miscible below the solubility limit of one of the compounds in the other compound, where each compound is usually a liquid solution at ambient conditions (about 20°C, about 1 atmosphere), although in some cases one or more of the compounds (e.g., solvents) may be solid at room temperature that is dissolved in the liquid solvent at room temperature.

[0025] "Immiscible" means that two or more compounds phase separate at a molar ratio (mol / mol) greater than the miscible molar ratio (i.e., above the solubility limit defined by the saturation point of one of the compounds in the other compound(s)).

[0026] "Miscibility point" refers to the maximum molar ratio (mol / mol) at which a compound (e.g., a solvent) is miscible with another compound, just short of phase separation to form a homogeneous solution, analogous to the saturation point of a solid dissolved in a liquid.

[0027] "Saturation point" refers to the molar ratio (mol / mol) at which a compound (e.g., a salt) is present in a solvent, i.e., the maximum molar amount of compound that can be dissolved in the solvent before equilibrium phase separation.

[0028] A "saturated solution" contains an amount of soluble compound greater than the saturation point such that some of the soluble compound is precipitated.

[0029] "Soluble" means that the solid compound is capable of dissolving in a solvent or solvent solution below the saturation point, for example, a salt dissolved in a solvent solution.

[0030] Unless otherwise specified, any characteristic or property may be determined by standard laboratory practices for determining such characteristic or property. Illustratively, boiling temperature, if not generally available in the literature, may be determined by ASTM D86. "Solubility" may be determined by the "shake flask" method based on guidelines provided by OECD, Paris, 1981, Test Guideline 107, Decision of the Council C(81)30 final. "Viscosity," if not generally available in the literature, may be determined by ASTM D445.

[0031] A battery is composed of a cathode, an anode, a separator, and an electrolyte. It is understood that each of these components may be connected to or contained within other common battery components, such as current collectors coated with the anode and cathode, and a battery container containing battery components with electrical connections to the battery. For example, the current collector may be any suitable metal (e.g., Al, alloys of Al and Cu, and alloys of Cu) foil, sheet, etc., such as a metal foil that may be further coated with a conductive material such as carbon, including those described in U.S. Pat. No. 9,172,085, incorporated herein by reference.

[0032] The cathode may comprise any material sufficient to have the desired discharge capacity and charge retention when used with the anode and the localized high-concentration electrolyte. Examples of suitable cathode materials may include phosphates, fluorophosphates, fluorosulfates, fluorosilicates, spinels, lithium-rich layered oxides, and composite layered oxides. Further examples of suitable cathode materials include spinel-structured lithium metal oxides, layered-structured lithium metal oxides, lithium-rich layered-structured lithium metal oxides, lithium metal silicates, lithium metal phosphates, metal fluorides, metal oxides, sulfur, metal sulfides, disordered rock-salt structures, or any combination thereof.

[0033] In a disordered rock-salt cathode, both lithium and transition metals occupy octahedral sites in a cubic close-packed lattice. In the electrochemical reaction, lithium diffusion proceeds by hopping from one octahedral site to another via intermediate tetrahedral sites. Lithium at an intermediate tetrahedral site is the activated state for lithium diffusion. An activated tetrahedral lithium ion shares faces with four octahedral sites: (i) the site previously occupied by the lithium ion itself, (ii) a vacancy into which the lithium ion can migrate, and (iii & iv) two sites that can be occupied by lithium, transition metal, or a vacancy.

[0034] The composition comprises: Li x M' y M z O 2-(a+b) F a Z b In the formula, 1.0 <x<1.75であり、0.01<y<0.55であり、0.1<z<1であり、0≦(a+b)<0.7であり、(b> or =0) M' is one of Ti, Ta, Zr, W, Nb, or Mo; M is one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh, and Sb; and Z is one or more of P, N, and S.

[0035] The amount of F and Z can be a major or minor component of the anions (i.e., O, F, and one or more of P, S, and N). Illustratively, (a+b) is 0.05 to 1.5, 1, 0.95, 0.8, 0.65, or 0.5. It may be desirable for a to be 0.05 to 0.25. Z may be any combination of P, N, and S, or just one of them. The ratio of P, N, and S, when more than one is present, may be any useful ratio depending on the desired attributes. For example, if a reduction in redox potential is desired, it may be desirable for S to be present. It may also be desirable for S to be the major component of P, S, and N present in the composition.

[0036] The composition can have any desired Li of 1 or greater, but it may be desirable for Li to be at least 1.1, 1.15, 1.2-1.65, 1.5, or 1.4, as represented by x.

[0037] The cations of the composition may be any of the listed metals, but desirably, at least one of the metals represented by M includes one or more of Ti, Mn, Fe, Co, V, Cr, Ni, and Cu. M may desirably include Ti and Mn. Illustratively, the composition may be one in which M' includes Nb. When Nb is present, M may desirably include Mn. Illustratively, M' may be Nb and M may be Mn. When Nb and Mn are present with or without other metals, they may be present in a Mn / Nb molar ratio of 1 to 10, 1 to 5, 2 to 10, or 2 to 5.

[0038] The disordered rock salt form can be made by any suitable method, such as those known in the art for making disordered rock salt forms. Exemplary methods are described in U.S. Patent Nos. 10,280,092, 10,978,706, and ACS Appl Mater Interfaces. 2019 Oct 2; 11(39):35777-35787, each of which is incorporated herein by reference.

[0039] Illustratively, the irregular rock salt material preferably comprises micro-sized clusters or agglomerates of sub-micron-sized particles, which can be useful for increasing the capacity and energy density of a battery cathode. The micro-sized clusters are also referred to herein as secondary particles. The secondary particles preferably have an average particle size (e.g., diameter) on the micrometer scale, such as 1 micrometer to 20 micrometers. The sub-micron-sized particles aggregate to form secondary particles. The sub-micron-sized particles are also referred to herein as primary particles. The terms "primary" and "secondary" indicate that the primary particles are formed before the secondary particles, and that the secondary particles are agglomerates of the primary particles. The primary particles have an average particle size (e.g., diameter) on the nanometer scale, such as less than 400 nanometers. The sub-micron primary particles of the irregular rock salt material can provide desirable electrical conductivity, while the micro-sized secondary particles of the irregular rock salt material result in high electrode energy density.

[0040] The battery cathode may alternatively include any suitable lithium metal phosphate, such as those known in the art. Exemplary lithium metal phosphates include those containing manganese, iron, or a combination thereof. The lithium metal phosphate may be doped with small amounts (up to 5% by weight) of other metals.

[0041] The cathode may further include other cathode components, such as a binder and a conductive additive. The binder may be any suitable binder known in the art, such as carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or a mixture of two or more thereof. Desirably, the cathode includes PVDF. The conductive additive may be graphite, carbon black, carbon nanotubes, graphene, carbon fiber, or the like.

[0042] The amount of other cathode components can be any suitable amount, but is generally from about 20% or 10% by volume to about 0.1%, 0.5%, or 1% by volume of the cathode (i.e., lithium metal phosphate and other cathode components).

[0043] The anode may comprise any material sufficient to function as an anode with the selected cathode and localized high concentration electrolyte. The anode may comprise one or more of graphite, lithium, lithium alloys, silicon, and silicon alloys. When the anode is a lithium alloy or lithium metal, the electrolyte may be formulated so that the formation of additional lithium surface area or lithium dendrites is reduced as the battery is cycled. Examples of suitable anode materials include lithium, graphite ("Li"). × C6"), and other carbon, silicon, or oxide-based anode materials.

[0044] The anode may be composed of graphitic carbon. The graphitic carbon may be any carbon capable of intercalating lithium, and while the carbon exhibits short-range order, it is understood that limited long-range order that appears amorphous by X-ray diffraction may be used. The graphitic carbon may illustratively be synthetic or natural graphite of sufficient purity for use in lithium-ion batteries, which generally requires a purity of at least about 99.5%, 99.9%, or 99.95%. Exemplary graphitic carbon may be spherical graphite, which is understood to be not perfectly spherical, but may be essentially ovoid, but not spalled. Spherical graphite generally has a high purity, such as at least 99.95%, but may also contain small amounts of oxides, such as silica, titania, and zirconia, or other materials capable of intercalating lithium, present in amounts less than 5% or 1% by volume of the cathode. The spherical graphite may be derived from synthetic graphite or purified natural graphite. Examples of useful spherical graphite are described in U.S. Patent Publication No. 2016 / 0141603 and U.S. Patent No. 9,276,257, each of which is incorporated herein by reference. Examples of suitable commercially available spherical graphite include those available from Syrah Resources, Magnis Resources, Northern Graphite, Focus Graphite, and Graphite One.

[0045] The separator may have one or more layers that may be bonded together. Examples of suitable separators include polyimides, polyolefins (such as polypropylene), polyethylene terephthalate, ceramic-coated polyolefins, cellulose, or a mixture of two or more thereof. Such materials may be in the form of microfibers or nanofibers. The separator may include a combination of microfibers and nanofibers. In certain embodiments, the separator includes polyethylene terephthalate microfibers and cellulose nanofibers. Examples of separators that may be useful are described in U.S. Patent Application No. 8,936,878, which is incorporated herein by reference. Further examples of separators include those available from Dreamweaver International (Greer, SC). Typically, separators are up to 250 micrometers thick to at least about 5 or 10 micrometers thick.

[0046] The electrolyte comprises a diluent, a solvating solvent, and a lithium salt. The diluent and solvating solvent may be contacted in a miscible molar ratio as described below.

[0047] The lithium salt may be any salt sufficient to be surrounded by the solvation structure of the solvating solvent and / or diluent in the electrolyte. The lithium salt may have a solubility in the solvating solvent relative to its solubility in the diluent, thereby making the diluent and solvating solvent miscible at a miscible molar ratio with improved discharge capacity and capacity retention. For example, the lithium salt may have a solubility greater than zero in the diluent. The lithium salt may have a solubility of about 1 M or greater, about 3 M or greater, or about 5 M or greater in the solvating solvent. The lithium salt may have a solubility of about 20 M or greater, about 15 M or greater, or about 10 M or greater in the solvating solvent. The lithium salt may be about 3 to about 20 times, about 3 to about 15 times, about 3 to about 10 times, about 5 to about 20 times, about 5 to about 15 times, about 5 to about 10 times, about 10 to about 20 times, or about 10 to about 15 times more soluble in the solvating solvent than the solubility of the diluent in the solvating solvent. The lithium salt may be saturated in the combination of the solvating solvent and diluent at about 1 M or more, about 2 M or more, or about 5 M or more relative to the concentration of the lithium salt in the solvating solvent alone. The lithium salt may be saturated in the combination of the solvating solvent and diluent at about 20 M or less, about 10 M or less, or about 7 M or less relative to the concentration of the lithium salt in the solvating solvent alone.

[0048] The concentration at which the lithium salt reaches its saturation point in the electrolyte can vary depending on the miscibility molar ratio of the diluent / solvating solvent. For example, the lithium salt can be present in the electrolyte at a concentration of about 0.1 M or greater, about 0.5 M or greater, or about 1.0 M or greater. The lithium salt can be present in the electrolyte at a concentration of about 3.5 M or greater, about 2.0 M or greater, or about 1.5 M or greater. The combination of the lithium salt and the diluent / solvating solvent can be present in the electrolyte at a molar ratio of about 1:2 or greater, 1:2.6 or greater, or 1:3.2 or greater. The combination of the lithium salt and the diluent / solvating solvent can be present in the electrolyte at a molar ratio of about 1:6 or greater, 1:5 or greater, or 1:4 or greater.

[0049] The electrolyte can include any number of lithium salts that are soluble in combination in a miscible molar ratio of diluent to solvating solvent. The electrolyte can include a single salt, or the electrolyte can include two or more, three or more, four or more, or multiple salts. When a combination of lithium salts is used, each lithium salt can have a different saturation point with the solvating solvent, diluent, or a combination of both in the electrolyte solution. For example, a first lithium salt can have a saturation point that is about 1%, 5%, or 10% to about 50%, 35%, or 20% higher or lower than the saturation point of a second lithium salt in the solvating solvent, diluent, or a combination of both in the electrolyte solution.

[0050] When a combination of lithium salts is used, each of the lithium salts can be different from the other. It has been found that different salts can be consumed at different rates by the anode, cathode, or solid electrolyte interface (SEI) layer, which can be assisted by having different saturation points in the solvation solvent, diluent, or a combination thereof. When two or more lithium salts are used, one lithium salt may replace another in the solvation structure as the battery cycles, and as the lithium salt is consumed, the solvation structure is maintained and the electrolyte remains stable. Desirably, a combination of salts such as LiFSI and LiBF4 has been found to improve the capacity retention of batteries containing high energy density cathodes, such as those containing disordered rock salt salts.

[0051] The lithium salt may include lithium bis(oxalato)borate (LiBOB), lithium bis(pentafluoroethylsulfonyl)imide (Li-BETI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF), lithium trifluoromethanesulfonate (LiTriflate), lithium hexafluoroarsenate (LiAsF), lithium bis(trifluoromethanesulfonimide) (LiTFSI), and lithium hexafluorophosphate (LiPF), lithium nitrate (LiNO), LiN(SOCF), LiN(SOF), LiCFSO, LiClO, lithium difluorooxalatoborate anion (LiDFOB), LiI, LiBr, LiCl, LiOH, LiSO, or any combination thereof.

[0052] In some embodiments, the electrolyte can include another salt, such as another alkali metal salt, an alkaline earth metal salt, or any combination thereof. For example, the lithium salt can include a sodium salt, a magnesium salt, a mixture of a lithium salt and a sodium salt, a mixture of a lithium salt and a magnesium salt, a mixture of a lithium salt, a magnesium salt, and a sodium salt, a mixture of a sodium salt and a magnesium salt, or any combination thereof. For example, the lithium salt can include sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethylsulfonyl)imide (NaTFSI), sodium bis(oxalato)borate (NaBOB), NaFSI, NaTFSI, any lithium salt, or any combination thereof.

[0053] The diluent and solvating solvent can be contacted with the electrolyte in a miscible molar ratio. A diluent can be used in an amount such that the diluent and solvating solvent are miscible when the lithium salt is dissolved in the solvating solvent. For example, in the presence of a lithium salt, the diluent and solvating solvent can be immiscible at a diluent / solvating solvent molar ratio of about 0.5 or more, about 1.5 or more, about 2.0 or more, 2.5 or more, about 3.5, or about 5.0 or more to essentially completely miscible, or about 20 or less, or about 10 or less.

[0054] The diluent can function to reduce the viscosity of the electrolyte while maintaining the desired high-salt concentration properties useful in batteries. For example, when a diluent is added to a solution of a solvating solvent and a lithium salt, the viscosity of the solution is reduced and advantageous properties can be maintained or realized. The viscosity of the diluent is desirably lower than that of the solvating solvent, desirably at least 5%, 10%, 25%, or 50% lower than that of the solvating solvent. The viscosity of the solution can be any amount sufficient to form an electrolyte having the desired discharge capacity and / or capacity retention. For example, the viscosity of the solution can be about 0.1 cP or more, about 3 cP or more, or about 5 cP or more. The viscosity of the solution can be about 15 cP or less, about 10 cP or less, or about 7 cP or less.

[0055] The diluent can have any level of miscibility with the solvating solvent sufficient for use in a localized high-concentration electrolyte. For example, the diluent can be fully miscible or can have a miscibility point in the solvating solvent of at most 10 (moles of diluent / moles of solvating solvent), about 5, or about 3 to at least about 0.5 or about 1. Surprisingly, it has been discovered that for diluents with limited miscibility in the solvating solvent, improved discharge capacity and capacity retention can be achieved in some cases when the diluent is used in a molar ratio within 50%, 25%, or 10% of the miscibility point of the diluent. Illustratively, the diluent can have a miscibility point of about 2 to about 5, or about 2 to about 3, where the molar ratio of diluent to solvent in the electrolyte is less than 50%, 25%, or 10% of the miscibility point of the diluent in the solvating solvent. Compared to the saturation point of the lithium salt in the solvating solvent, the miscibility point of the diluent in the solvating solvent can be about one-third to about one-fifteenth, about one-third to about one-tenth, about one-third to about one-eighth, about one-fifth to about one-fifteenth, about one-fifth to about one-tenth, or about one-fifth to about one-eighth of the saturation point of the lithium salt in the solvating solvent.

[0056] The miscibility of a diluent in a solvating solvent can vary based on the presence of a lithium salt dissolved therein. For example, a diluent may have higher or lower miscibility with the solvating solvent in the presence of a lithium salt, which may be below the saturation point in the solvating solvent or solution. A diluent may have a miscibility in a solvating solvent with a dissolved salt that is 1% to 20%, 10%, or 5% of the miscibility point of the diluent in the undiluted solvating solvent, and it is desirable for the diluent to have higher miscibility in the presence of a salt in the solvating solvent.

[0057] The diluent may have a miscibility in the solvating solvent that differs from the solubility of the lithium salt in the solvating solvent. For example, the lithium salt may be about 3 molar times, about 5 molar times, or about 7 molar times to about 10 molar times, about 13 molar times, or about 15 molar times more soluble in the solvating solvent than the miscibility of the diluent in the solvating solvent. Illustratively, it may be desirable for the diluent to have a miscibility point of 2 or 3-5 molar ratio, the amount of diluent present being within 10%, 25%, or 50% of the miscibility point, and the amount of salt that can be dissolved in the diluent being 5-10, 5-9, 5-8, 6-10, 6-9, or 6-8 times less than the amount of salt that can be dissolved in the solvating solvent.

[0058] The structure of the diluent may affect the miscibility of the solvating solvent with the diluent. For example, a diluent having a linear alkyl group on the diluent may have a different miscibility in the solvating solvent compared to the miscibility of a diluent having a branched alkyl group. For example, the solvating solvent may be immiscible with the diluent at a lower molar ratio when the branched alkyl group is present in the diluent compared to when only the linear alkyl group is present in the diluent, while still achieving the desired discharge capacity and capacity retention.

[0059] The electrolyte can include a combination of diluents with different substitutions, for example, a combination of diluents containing linear alkyl groups, branched alkyl groups, or both, can provide different miscible molar ratios with the solvating solvent while achieving desirable discharge capacity and capacity retention.

[0060] The electrolyte can include any number of different diluents sufficient to be miscible with the solvating solvent and / or to adjust the viscosity of the electrolyte, for example, the electrolyte can include one or more, two or more, three or more, four or more, or multiple diluents.

[0061] The diluent may comprise one or more fluorinated ethers, which may be any compound containing a combination of ether groups fully saturated with hydrogen, fluorine atoms, and carbon atoms.

[0062] Examples of fluorinated ethers include 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE); bis(2,2,2-trifluoroethyl) ether (BTFE), hexafluoroisopropyl methyl ether (HFPME); 1,1,2,2-tetrafluoroethyl ethyl ether (TFEEE); 1H,1H,5H-octafluoropentyl 1,1,2,2-tetrafluoroethyl ether (OFPTFEE); 1,1,2,2-tetrafluoroethyl ether, 1 ,2-(1,1,2,2-tetrafluoroethoxy)ethane (TFEE); 1,3-(1,1,2,2-tetrafluoroethoxy)propane (TFEP); 1,1,2,3,3,3-hexafluoropropyl 2,2,2-trifluoroethyl ether (HFPTFEE); n-butyl 1,1,2,2-tetrafluoroethyl ether (BTFEE); 1H,1H,2'H,3H-decafluorodipropyl ether (DFDPE); 1,1,2,3,3,3-hexafluoropropyl ethyl ether (HFPEE) 1,1,1-Trifluoro-2-[1-(2,2,2-trifluoroethoxy)ethoxy]ethane (TTFEEE); 1H,1H,2'H-Perfluorodipropyl ether (PFDPE); 1,1,2,2-Tetrafluoroethyl isobutyl ether (TFEBE); 1,1,1,2,2,3,4,5,5,5-Decafluoro-2-methoxy-4-(trifluoromethyl)pentane; 1-(ethoxy)nonafluorobutane with a mixture of n- and iso-butyl isomers; 2-(trifluoromethyl)-3-ethoxy 3-methoxyperfluoro(2-methylpentane); heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether; 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (TFTFE); methoxynonafluorobutane (MOFB); ethoxynonafluorobutane (EOFB); tris(2,2,2-trifluoroethyl)orthoformate; and di(2,2,2-trifluoroethyl)carbonate.

[0063] The solvating solvent can function to provide a solvation structure around the anions and / or cations of the lithium salt. To achieve a desired amount of salt dissolution in the electrolyte, a portion of the salt can be dissolved in a diluent, thereby improving battery performance. The lithium salt can be first dissolved in the solvating solvent at or near its saturation point to form a solvating solvent-salt solution. A diluent can then be added to the solvating solvent-salt solution to form the electrolyte. Additional salt can be added up to or near the saturation point of the salt in the electrolyte.

[0064] Because some of the lithium salt is soluble in the diluent, after the diluent is added to the solution of the solvating solvent and lithium salt, additional amounts of lithium salt can be added up to or below the saturation point of the solution. By way of example, the amount of salt can be any useful concentration, generally essentially at or just below the saturation point, but can be adjusted depending on, for example, the expected operating conditions of a particular battery (e.g., the amount of salt can be within 20%, 10%, or 5% of the saturation point of the solvating solvent-diluent solution at ambient conditions). Additional lithium salt can be added to the combination of diluent and solvating solvent up to the saturation point of the solvating solvent, where the diluent and solvating solvent are in a miscible molar ratio as described above. The amount of salt in the solvating solvent-diluent solution can exceed the saturation point of the solvating solvent alone. For example, the amount of salt in solution is about 1 percent to about 25 percent, about 1 percent to about 10 percent, about 5 percent to about 25 percent, or about 5 percent to about 10 percent above the saturation point of the solvating solvent alone, based on the saturation point of the lithium salt in the solvating solvent alone. A lithium salt amount less than saturation of the solvating solvent-diluent solution may be desirable due to viscosity parameters or battery performance considerations.

[0065] In some examples, the diluent and solvating solvent can be contacted first, and then the lithium salt can be contacted with the combination of diluent and solvating solvent in amounts up to or below the saturation point of the combined diluent and solvating solvent. When the lithium salt is contacted with the solvating solvent, diluent, or both in amounts above the saturation point of the solvating solvent, diluent, or both, a saturated solution is formed and the precipitated lithium salt can be removed from the saturated solution. When the lithium salt is contacted with the solvating solvent, diluent, or both in amounts above the saturation point of the solvating solvent, diluent, or both, the precipitated lithium salt can be removed from the saturated solution before or after adding the diluent.

[0066] The solvating solvent has a solubility with the lithium salt that differs from the solubility of the lithium salt in the diluent. The solubility of the lithium salt in the diluent and solvating solvent can affect the miscibility molar ratio of the diluent / solvating solvent when the lithium salt is present below saturation. For example, when a lithium salt is present at saturation in a solution of the solvating solvent and diluent, the miscibility molar ratio of the diluent / solvating solvent can be higher or lower than when the lithium salt is not present.

[0067] A solvating solvent can be included based on a lithium salt present at or below its saturation point, thereby reducing the ability of the lithium salt to immobilize the solvating solvent and form an SEI layer. The diluent and solvating solvent can be contacted at, above, or below a miscible molar ratio. Contacting the diluent and solvating solvent at or below the miscible molar ratio can provide excellent discharge capacity and / or capacity retention. In some embodiments, when the solvating solvent, diluent, and lithium salt are contacted, the lithium salt can be present at a concentration that is below the saturation point of the diluent / solvating solvent miscible molar ratio to improve the discharge capacity and / or capacity retention of the battery.

[0068] The solvating solvent can have any viable salt saturation point for making an electrolyte. The saturation point of the salt in the solvating solvent can be a molar ratio of at least 1, about 2, or about 3 to about 10 or about 20. The viscosity of the solvating solvent can be any viscosity useful for making a battery. The viscosity of the solvating solvent at room temperature (about 20°C) can be 1 cP or more, 20 cP or more, or 50 cP or more to 200 cP or less, 100 cP or less, or 200 cP or less. Note that in some cases, the solvating solvent can be solid at room temperature. In such cases, solubilization of the salt occurs by freezing point depression, causing the solvent to become liquid.

[0069] The solvating solvent can be any solvent or combination of solvents that is sufficiently miscible with the diluent and capable of sufficiently dissolving the lithium salt, with or without the diluent. The electrolyte can include any number of solvating solvents sufficient to form the desired solvation around the cations and / or anions of the lithium salt. For example, the electrolyte can include one or more, two or more, three or more, four or more, or multiple solvating solvents. The solubility of each salt in the solvating solvent and / or diluent can be essentially the same and / or different. For example, it can be desirable to have one salt that is highly soluble in the diluent (e.g., 5%, 10%, or 20% more soluble than the other salts), which can be desirable in forming an advantageous SEI layer. In some examples, the solvating solvent can include one or more of a dialkoxyalkane, a dialkyl glycol ether, a disubstituted ester, a disubstituted carbonate, a trisubstituted phosphate, a disubstituted sulfone, and a tetrasubstituted silane.

[0070] Dialkoxyalkanes are C alkyl groups that can be branched or linear. 1~12 The dialkoxyalkane may include a pair of alkyl ethers linked by an alkane group. For example, the dialkoxyalkane may include one or more of dimethoxyethane (DME), diethoxyethane (DEE), and 1,2-dimethoxypropane (DMP), and the dialkoxyalkane may have the following structure: [ka] wherein each R1 may independently have a C 1~12 alkyl groups, or any combination thereof; Each R2 is a C 1~12 alkyl groups, or any combination thereof; n is an integer of 1 to 5.

[0071] Dialkyl glycol ethers may include a series of three ether groups separated by an alkyl chain, which may be linear or branched. Examples of dialkyl glycol ethers may include 1,2-diethylene glycol isopropyl methyl ether (DEGIM), diethylene glycol butyl methyl ether (DEGBM), or any combination thereof. Dialkyl glycols have the following structure: [ka] wherein each R1 may independently have a C 1~12 alkyl groups, or any combination thereof; Each R2 is independently a C 1~12 alkyl groups, or any combination thereof; Each n is an integer from 1 to 5.

[0072] Disubstituted esters are those in which the carbon atom of the carbonyl or the oxygen atom of the hydroxyl group is replaced by a hydrogen, C 1~12 Alkyl, C 1~12 The disubstituted ester may include esters substituted with one or more groups including aryl, or any combination thereof. Examples of disubstituted esters may include ethyl difluoroacetate, ethyl propionate, or any combination thereof. Disubstituted esters may have the following structure: [ka] wherein each R1 is independently a hydrogen atom, a C 1~12 It may comprise an alkyl group, a heteroalkyl group which may be linear or branched, or any combination thereof. Both R1 may combine to form a cyclic alkyl ring which may optionally contain one or more heteroatoms.

[0073] The disubstituted carbonate may be independently substituted at each carbon atom. The disubstituted carbonate may include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, fluoroethylene carbonate, or any combination thereof. The disubstituted carbonate may have the following structure: [ka] wherein each R1 is independently a hydrogen atom, a C 1~12 It may comprise an alkyl group, a heteroalkyl group which may be linear or branched, or any combination thereof. Both R1 may combine to form a cyclic alkyl ring which may optionally contain one or more heteroatoms.

[0074] The tri-substituted phosphate may be substituted at each of the single-bonded oxygen atoms. The tri-substituted phosphate may include trimethyl phosphate, triethyl phosphate, or any combination thereof. The tri-substituted ester has the following structure: [ka] wherein each R1 is independently a hydrogen atom, a C 1~12 may contain alkyl groups, heteroatoms, heteroalkyl groups, or any combination thereof; Each R2 is independently a hydrogen atom, a C 1~12 alkyl groups, or any combination thereof.

[0075] Disubstituted sulfones have hydrogen, C, and 1~12 Alkyl, C1~12 The disubstituted sulfone may be substituted with one or more groups including aryl, aryl, or any combination thereof. The disubstituted sulfone may include sulfolane, methyl ethyl sulfone, methyl isopropyl sulfone, or any combination thereof. The disubstituted sulfone may have the following structure: [ka] wherein each R1 is independently a hydrogen atom, a C 1~12 It may comprise an alkyl group, a heteroalkyl group which may be linear or branched, or any combination thereof. Both R1 may combine to form a cyclic alkyl ring which may optionally contain one or more heteroatoms.

[0076] The tetrasubstituted silane may be substituted at the silicon atom and / or each oxygen atom. The tetrasubstituted silane may include triethoxymethylsilane, trimethoxymethylsilane, or any combination thereof. The tetrasubstituted silane may have the following structure: [ka] wherein each R3 is independently a hydrogen atom, a C 1~12 alkyl groups, heteroatoms, heteroalkyl groups, which may be linear or branched C1~12 It may contain alkoxy groups, heteroatoms, heteroalkyl groups, or any combination thereof.

[0077] The battery may have a discharge capacity or capacity retention that depends at least in part on the molar ratio of the selected solvent to the diluent and solvating solvent. For example, the structure of the diluent, including branched or linear alkyl groups, may change the discharge capacity or capacity retention. In another example, lowering or increasing the diluent / solvating solvent molar ratio based on solvent miscibility or diluent structural considerations may change the discharge capacity or capacity retention. The battery may have a discharge capacity of about 120 mAh / g or more, about 140 mAh / g or more, or about 160 mAh / g or more. The battery may have a discharge capacity of about 220 mAh / g or less, about 200 mAh / g or less, or about 180 mAh / g or less. The battery may have a capacity retention at 80 percent for about 40 cycles or more, about 90 cycles or more, or about 140 cycles or more. The battery may have a capacity retention at 80 percent for about 200 cycles or less, about 180 cycles or less, or about 160 cycles or less.

[0078] Enumeration of Embodiments The following embodiments are intended to be illustrative, and not to unduly limit the scope of the present disclosure.

[0079] Embodiment 1. A battery, a cathode comprising a disordered rock-salt structure; and An electrolyte, a solvating solvent; a lithium salt soluble in the solvating solvent; the electrolyte comprising a diluent miscible with the solvating solvent; the lithium salt is at least 5 times more soluble in the solvating solvent than in the diluent, and the solvating solvent and the diluent are present in the battery at a diluent / solvating solvent ratio of 0.1 to less than 3.0.

[0080] Embodiment 2. The battery of embodiment 1, wherein the diluent has a miscibility point in the solvation solvent and the salt has a saturation point in the solvation solvent, whereby the saturation point is at least 5 times higher than the miscibility point.

[0081] Embodiment 3. The battery of embodiment 1 or 2, wherein the diluent and the solvating solvent are immiscible at a molar ratio of diluent / solvating solvent of 5 or greater.

[0082] Embodiment 4. The battery of any one of embodiments 1 to 3, wherein the diluent and the solvating solvent are present in a molar ratio of 1.0 to 3.0.

[0083] Embodiment 5. The battery of any one of embodiments 1-4, wherein the lithium salt and the combination of the solvating solvent and the diluent are present in a molar ratio of 1:2 or greater.

[0084] Embodiment 6. The battery of any one of embodiments 1-5, wherein the lithium salt is present at a concentration of about 0.5 M or greater at its saturation point within the solvating solvent or the solvating solvent / diluent combination.

[0085] Embodiment 7. The battery of any one of embodiments 1-6, wherein the solvation solvent comprises one or more of a dialkoxyalkane, a dialkyl glycol ether, a disubstituted ester, a disubstituted carbonate, a trisubstituted phosphate, a disubstituted sulfone, and a tetrasubstituted silane.

[0086] Embodiment 8. The battery of any one of embodiments 1 to 7, wherein the solvating solvent comprises a disubstituted carbonate.

[0087] Embodiment 9. A battery, a cathode, and An electrolyte, a solvating solvent; a lithium salt comprising a first lithium salt and a second lithium salt soluble in the solvation solvent, the second salt being present at a concentration that is less than or equal to the concentration of the first salt; and a diluent that is miscible with the solvation solvent; the lithium salt is at least 5 times more soluble in the solvating solvent than in the diluent, and the solvating solvent and the diluent are present in the battery at a diluent / solvating solvent ratio of 0.1 to less than 3.0.

[0088] Embodiment 10. The battery of embodiment 9, wherein the first and second lithium salts are present in the solvating solvent or the solvating solvent / diluent combination in a molar ratio of 1 or greater, up to and including the saturation point.

[0089] Embodiment 11. The battery of embodiment 10, wherein the first and second lithium salts are present in the solvating solvent or the solvating solvent / diluent combination in a molar ratio of 2 or greater, up to and including the saturation point.

[0090] Embodiment 12. The battery of any one of the preceding embodiments, wherein the diluent and the solvating solvent are immiscible at a diluent / solvating solvent molar ratio of 5.0 or greater.

[0091] Embodiment 13. The battery of embodiment 10, wherein the concentrations of the first lithium salt and the second lithium salt are within about 20% of phase separation in the electrolyte.

[0092] Embodiment 14. The battery of any one of the preceding embodiments, further comprising an anode comprising one or more of graphite, lithium, a lithium alloy, silicon, and a silicon alloy.

[0093] Embodiment 15. The battery of any one of embodiments 9-14, wherein the cathode is chargeable to a voltage of 4.45 or greater.

[0094] Embodiment 16. The battery of any one of embodiments 9-15, wherein the cathode comprises a disordered rock salt structure.

[0095] Embodiment 17. The battery of any one of embodiments 9-16, wherein the first lithium salt and second lithium salt are present in a molar ratio to the combination of the solvating solvent and diluent of from about 1:2.5 to about 1:5.

[0096] Embodiment 18. The battery of any one of embodiments 9 to 17, wherein the first lithium salt and second lithium salt are present in a molar ratio of about 9:1 to about 1:1.

[0097] Embodiment 19. The battery of any one of embodiments 9-18, wherein the first lithium salt comprises lithium bis(oxalato)borate (LiBOB), lithium bis(pentafluoroethylsulfonyl)imide (Li-BETI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF), lithium trifluoromethanesulfonate (LiTriflate), lithium hexafluoroarsenate (LiAsF), lithium bis(trifluoromethanesulfonimide) (LiTFSI), and lithium hexafluorophosphate (LiPF), lithium nitrate (LiNO), LiN(SOCF), LiN(SOF), LiCFSO, LiClO, lithium difluorooxalatoborate anion (LiDFOB), LiI, LiBr, LiCl, LiOH, LiSO, or any combination thereof.

[0098] Embodiment 20. The battery of any one of embodiments 9-19, wherein the second lithium salt is a lithium salt different from the first salt and includes lithium bis(oxalato)borate (LiBOB), lithium bis(pentafluoroethylsulfonyl)imide (LiBETI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF), lithium trifluoromethanesulfonate (LiTriflate), lithium hexafluoroarsenate (LiAsF), lithium bis(trifluoromethanesulfonimide) (LiTFSI), and lithium hexafluorophosphate (LiPF), lithium nitrate (LiNO), LiN(SOCF), LiN(SOF), LiCFSO, LiClO, lithium difluorooxalatoborate anion (LiDFOB), LiI, LiBr, LiCl, LiOH, LiSO, or any combination thereof.

[0099] Embodiment 21. The battery of any one of the preceding embodiments, wherein the battery has a capacity retention of 80 percent at or above 100 cycles.

[0100] Embodiment 22. The battery of any one of the preceding embodiments, wherein the battery has a capacity retention of 80 percent at or above 120 cycles.

[0101] Embodiment 23. The battery of embodiment 21 or 22, wherein the battery has a capacity of about 180 mAh / g or greater.

[0102] Embodiment 24. The battery of embodiment 21 or 22, wherein the battery has a capacity of about 200 mAh / g or greater.

[0103] Embodiment 25. The battery of any one of the preceding embodiments, wherein the diluent comprises a fluorinated ether.

[0104] Embodiment 26. The fluorinated ether is 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether; bis(2,2,2-trifluoroethyl) ether, hexafluoroisopropyl methyl ether; 1,1,2,2-tetrafluoroethyl ethyl ether; 1H,1H,5H-octafluoropentyl 1,1,2,2-tetrafluoroethyl ether; 1,1,2,2-tetrafluoroethyl ether, 1,2-(1, 1,2,2-tetrafluoroethoxy)ethane; 1,3-(1,1,2,2-tetrafluoroethoxy)propane (TFEP); 1,1,2,3,3,3-hexafluoropropyl 2,2,2-trifluoroethyl ether; n-butyl 1,1,2,2-tetrafluoroethyl ether; 1H,1H,2'H,3H-decafluorodipropyl ether; 1,1,2,3,3,3-hexafluoropropyl ethyl ether; 1,1,1-trifluoro-2-[ 1-(2,2,2-trifluoroethoxy)ethoxy]ethane; 1H,1H,2'H-perfluorodipropyl ether, 1,1,2,2-tetrafluoroethyl isobutyl ether; 1,1,1,2,2,3,4,5,5,5-decafluoro-2-methoxy-4-(trifluoromethyl)pentane; 1-(ethoxy)nonafluorobutane with a mixture of n- and iso-butyl isomers; 2-(trifluoromethyl)-3-ethoxydodecafluorohexane; 26. The battery of embodiment 25, comprising one or more of: 3-methoxyperfluoro(2-methylpentane); heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether; 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether; methoxynonafluorobutane; ethoxynonafluorobutane; tris(2,2,2-trifluoroethyl)orthoformate; and di(2,2,2-trifluoroethyl)carbonate.

[0105] Embodiment 27. The battery of any one of embodiments 9-26, wherein the solvation solvent comprises a dialkoxyalkane, a dialkyl glycol ether, a disubstituted ester, a disubstituted carbonate, a trisubstituted phosphate, a disubstituted sulfone, and a tetrasubstituted silane, or any combination thereof.

[0106] Embodiment 28. The battery of any one of the preceding embodiments, further comprising a separator comprising a nonwoven fabric, a microporous film, a ceramic, or any combination thereof.

[0107] Embodiment 29. A method of forming an electrolyte, comprising: dissolving lithium salts, including a first lithium salt and a second lithium salt, in a solvating solvent to form a solvating solvent-lithium salt solution; dissolving a diluent in the solvating solvent-lithium salt solution; further dissolving more of the first lithium salt or the second lithium salt to a concentration that exceeds the amount of the lithium salt soluble in the solvation solvent to form the electrolyte.

[0108] Embodiment 30. The method of embodiment 29, wherein the first lithium salt and / or the second lithium salt present in the electrolyte is below the saturation point of the lithium salt in the electrolyte.

[0109] Embodiment 31. The method of embodiment 29 or 30, wherein the first lithium salt and / or the second lithium salt have different saturation points in the solvating solvent-lithium solution and the electrolyte.

[0110] Embodiment 32. An electrolyte comprised of a solvating solvent, a diluent, and a lithium salt, including a first lithium salt and a second lithium salt, wherein the electrolyte is a solution having a saturation point, the solvating solvent has a saturation point, the lithium salt is at least 5 times more soluble in the solvating solvent, and the first lithium salt and the second lithium salt are present in amounts below the saturation point of the electrolyte and above the saturation point of the solvating solvent, if present in the absence of the diluent.

[0111] Embodiment 33. The electrolyte of embodiment 32, wherein the first and / or second lithium salts have different saturation points in the electrolyte and the solvation solvent. [Example]

[0112] The following examples are intended to be illustrative, and not to unduly limit the scope of this disclosure.

[0113] Example 1 For Example 1, battery cells were fabricated in a glove box (M-Braun, O2 and humidity content <0.1 ppm) filled with high-purity argon. For the cathode, a disordered rock-salt cathode active material was mixed with polyvinylidene fluoride (PVDF), carbon black powder, and liquid 1-methyl-2-pyrrolidinone (NMP) to form a slurry. The resulting slurry was deposited on an aluminum current collector and dried to form a composite cathode film. For the anode, graphitic carbon was mixed with carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), carbon black powder, and deionized water to form a slurry. The resulting slurry was deposited on a copper current collector and dried to form a composite anode film. Each battery cell included a composite cathode film, a polypropylene separator, and a composite anode. A localized high-salt electrolyte was prepared in the following molar ratio: For example, lithium bis(fluorosulfonyl)imide (LiFSI), dimethyl carbonate (DMC), and 1,2-(1,1,2,2-tetrafluoroethoxy)ethane (TFEE) were mixed in a 1 / 1.6 / 2 molar ratio and added to a battery cell. The battery cell was then sealed and cycled at 30 °C using a 0.05 C discharge to an upper cutoff voltage of 4.55 V. The voltage was then held at a constant voltage until the current dropped to 0.02 C, and then discharged to 1.5 V using a 0.05 C constant current. The second cycle was changed to a 0.1 C discharge and discharged to complete the formation cycle. In the third cycle, a 0.1 C discharge was used for full discharge, and a 1 C discharge was used for rate performance evaluation. The cell was then cycled at 0.33 C / 0.33 C for performance evaluation.

[0114] Figure 1A shows the discharge capacity of various solvation solvents used in a disordered rock salt cathode, and Figure 1B shows the capacity retention of various solvation solvents used in a disordered rock salt cathode. [Table 1]

[0115] Table 1 shows the discharge capacity and capacity retention of different solvation solvents and diluents from Figures 1A-1B. Both dimethoxyethane (DME) and dimethyl carbonate (DMC) were evaluated as solvation solvents, as shown in Figures 1A-1B. A conventional electrolyte (i.e., the reference) with a low concentration of LiPF6 salt and an additive package of tris(trimethylsilyl)phosphate + LiDFOB reached 80% of its initial discharge capacity at 91 cycles. A localized high-concentration electrolyte containing DME (A3: LiFSI / DME / TTE = 1 / 1.2 / 3 per mole) performed poorly with a DR cathode and graphite anode as the DMC. A localized high-concentration electrolyte containing DMC as the solvation solvent showed desirable results when combined with a disordered rock salt cathode and graphite anode. Using TTE (A2) as the dilution solvent, in combination with DMC, shows better performance than BTFE (A1), which takes 149 cycles to reach 80% of the initial discharge capacity.

[0116] Example 2 For Example 2, the cell is set up the same as in Example 1, except the salt is changed.

[0117] 2A-2B show the discharge capacity and capacity retention of a single lithium salt compared to a dual lithium salt electrolyte. [Table 2]

[0118] Table 2 shows the results from Figures 2A-2B. Using a DMC / TTE solvating / diluting solvent combination, salt combinations were evaluated in a localized high-concentration electrolyte paired with a DR cathode and graphite anode. The formulation containing LiBF4 and LiFSI (A4) performed best.

[0119] Experimental Example 3 For Example 3, the battery and electrolyte are set up the same as in Example 1, except a different formulation of electrolyte is used.

[0120] 3A-3B show the discharge capacity and capacity retention of various diluents used in the disordered rock salt cathode. [Table 3]

[0121] The diluents for the localized high-concentration electrolytes included HFPME, TFEEE, OFPTFEE, TFEE, HFPTEE, BTFE, and TTE. The results are shown in Table 3.

[0122] As can be seen from Table 3, the localized high concentration electrolytes TFEE, TTE, and BTFE performed similarly or better than the conventional electrolyte of Figures 1A-1B (reference).

Claims

1. A battery, a cathode comprising a disordered rock-salt structure; and An electrolyte, a solvating solvent; a lithium salt soluble in the solvating solvent; a diluent miscible with the solvating solvent; The electrolyte comprises the lithium salt is at least five times more soluble in the solvating solvent than in the diluent, and the solvating solvent and the diluent are present in the battery in a diluent / solvating solvent molar ratio of 0.1 to less than 3.

0.

2. 2. The battery of claim 1, wherein the diluent has a miscibility point in the solvation solvent and the lithium salt has a saturation point in the solvation solvent, such that the saturation point of the lithium salt in the solvation solvent is at least 5 times higher than the miscibility point of the diluent in the solvation solvent.

3. 10. The battery of claim 1, wherein the diluent and the solvating solvent are immiscible at a molar ratio of diluent / solvating solvent of 5 or greater.

4. 10. The battery of claim 1, wherein the diluent and the solvating solvent are present in a molar ratio of 1.0 to 3.

0.

5. 10. The battery of claim 1, wherein the lithium salt and the combination of the solvating solvent and the diluent are present in a molar ratio of 1:2 or greater.

6. 10. The battery of claim 1, wherein the lithium salt is present at a concentration of about 0.5 M or greater at the saturation point within the solvating solvent, or within the solvating solvent and diluent.

7. 10. The battery of claim 1, wherein the solvating solvent comprises one or more of a dialkoxyalkane, a dialkyl glycol ether, a disubstituted ester, a disubstituted carbonate, a trisubstituted phosphate, a disubstituted sulfone, and a tetrasubstituted silane.

8. The battery of claim 7 , wherein the solvating solvent comprises the disubstituted carbonate.

9. 10. The battery of claim 1, further comprising an anode comprising one or more of graphite, lithium, a lithium alloy, silicon, and a silicon alloy.

10. 10. The battery of claim 1, wherein the battery has a capacity retention of 80 percent for 100 or more cycles.

11. 11. The battery of claim 10, wherein the battery has a capacity retention of 80 percent for 120 or more cycles.

12. 11. The battery of claim 10, wherein the battery has a capacity of about 180 mAh / g or greater.

13. 13. The battery of claim 12, wherein the battery has a capacity of about 200 mAh / g or greater.

14. The battery of claim 1 , wherein the diluent comprises a fluorinated ether.

15. The fluorinated ethers include 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether; bis(2,2,2-trifluoroethyl)ether, hexafluoroisopropyl methyl ether; 1,1,2,2-tetrafluoroethyl ethyl ether; 1H,1H,5H-octafluoropentyl 1,1,2,2-tetrafluoroethyl ether; 1,1,2,2-tetrafluoroethyl ether, 1,2-(1,1,2,2-tetrafluoroethoxy)ethane; 1,3-(1,1,2,2-tetrafluoroethoxy)propane (TFEP), 1,1,2,3,3,3-hexafluoropropyl 2,2,2-trifluoroethyl ether; n-butyl 1,1,2,2-tetrafluoroethyl ether; 1H,1H,2′H,3H-decafluorodipropyl ether, 1,1,2,3,3,3-hexafluoropropyl ethyl ether; 1,1,1-trifluoro-2-[1-(2,2,2-trifluoroethoxy)ethoxy]ethane; 1H,1H,2′H-perfluorodipropyl ether, 1,1,2,2-tetrafluoroethyl isobutyl ether; 15. The battery of claim 14 comprising one or more of 1,1,1,2,2,3,4,5,5,5-decafluoro-2-methoxy-4-(trifluoromethyl)pentane; 1-(ethoxy)nonafluorobutane having a mixture of n- and iso-butyl isomers; 2-(trifluoromethyl)-3-ethoxydodecafluorohexane; 3-methoxyperfluoro(2-methylpentane); heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether; 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether; methoxynonafluorobutane; ethoxynonafluorobutane; tris(2,2,2-trifluoroethyl)orthoformate; and di(2,2,2-trifluoroethyl)carbonate.

16. 10. The battery of claim 1, further comprising a separator comprising a nonwoven fabric, a microporous film, a ceramic, or any combination thereof.

17. A battery, a cathode, and An electrolyte, a solvating solvent; a lithium salt comprising a first lithium salt and a second lithium salt soluble in the solvation solvent, the second lithium salt being present at a concentration that is less than or equal to the concentration of the first lithium salt; a diluent that is miscible with the solvating solvent; The electrolyte comprises the lithium salt is at least five times more soluble in the solvating solvent than in the diluent, and the solvating solvent and the diluent are present in the battery at a diluent / solvating solvent ratio of 0.1 to less than 3.

0.

18. 18. The battery of claim 17, wherein the first and second lithium salts are present in the solvating solvent or solvating solvent / diluent combination in one or more molar ratios up to a saturation point.

19. 20. The battery of claim 18, wherein the first and second lithium salts are present in a molar ratio of 2 or greater relative to the saturation point within the solvating solvent or the solvating solvent / diluent combination.

20. 18. The battery of claim 17, wherein the solvating solvent and the diluent are immiscible at a diluent / solvating solvent molar ratio of 5.0 or greater.

21. 20. The battery of claim 18, wherein the first lithium salt and the second lithium salt are present in amounts within about 20% of phase separation in the electrolyte.

22. 20. The battery of claim 17, further comprising an anode comprising one or more of graphite, lithium, a lithium alloy, silicon, and a silicon alloy.

23. 20. The battery of claim 17, wherein the cathode is chargeable to a voltage of 4.45 or greater.

24. 20. The battery of claim 17, wherein the cathode comprises a disordered rock salt structure.

25. 18. The battery of claim 17, wherein the first lithium salt and second lithium salt are present in a molar ratio to the combination of the solvating solvent and diluent of from about 1:2.5 to about 1:

5.

26. 18. The battery of claim 17, wherein the first lithium salt and the second lithium salt are present in a molar ratio of about 9:1 to about 1:

1.

27. The first lithium salt is selected from the group consisting of lithium bis(oxalato)borate (LiBOB), lithium bis(pentafluoroethylsulfonyl)imide (Li-BETI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium tetrafluoroborate (LiBF ４ ), lithium trifluoromethanesulfonate (LiTriflate), lithium hexafluoroarsenate (LiAsF ６ ), lithium bis(trifluoromethanesulfonimide) (LiTFSI), and lithium hexafluorophosphate (LiPF ６ ), lithium nitrate (LiNO ３ ), LiN(SO ２ CF ３ ) ２ , LiN(SO ２ F) ２ , LiCF ３ SO ３ , LiClO ４ , lithium difluorooxalatoborate anion (LiDFOB), LiI, LiBr, LiCl, LiOH, LiSO ４ 18. The battery of claim 17, comprising:

28. The second lithium salt is a lithium salt different from the first lithium salt, and may be lithium bis(oxalato)borate (LiBOB), lithium bis(pentafluoroethylsulfonyl)imide (Li-BETI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF ４ ), lithium trifluoromethanesulfonate (LiTriflate), lithium hexafluoroarsenate (LiAsF ６ ), lithium bis(trifluoromethanesulfonimide) (LiTFSI), and lithium hexafluorophosphate (LiPF ６ ), lithium nitrate (LiNO ３ ), LiN(SO ２ CF ３ ) ２ , LiN(SO ２ F) ２ , LiCF ３ SO ３ , LiClO ４ , lithium difluorooxalatoborate anion (LiDFOB), LiI, LiBr, LiCl, LiOH, LiSO ４ 28. The battery of claim 27, comprising:

29. 20. The battery of claim 17, wherein the battery has a capacity retention of 80 percent for 100 or more cycles.

30. 30. The battery of claim 29, wherein the battery has a capacity retention of 80 percent for 120 or more cycles.

31. 30. The battery of claim 29, wherein the battery has a capacity of about 180 mAh / g or greater.

32. 32. The battery of claim 31, wherein the battery has a capacity of about 200 mAh / g or greater.

33. 18. The battery of claim 17, wherein the diluent comprises a fluorinated ether.

34. The fluorinated ethers include 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether; bis(2,2,2-trifluoroethyl)ether, hexafluoroisopropyl methyl ether; 1,1,2,2-tetrafluoroethyl ethyl ether; 1H,1H,5H-octafluoropentyl 1,1,2,2-tetrafluoroethyl ether; 1,1,2,2-tetrafluoroethyl ether, 1,2-(1,1,2,2-tetrafluoroethoxy)ethane; 1,3-(1,1,2,2-tetrafluoroethoxy)propane (TFEP), 1,1,2,3,3,3-hexafluoropropyl 2,2,2-trifluoroethyl ether; n-butyl 1,1,2,2-tetrafluoroethyl ether; 1H,1H,2′H,3H-decafluorodipropyl ether, 1,1,2,3,3,3-hexafluoropropyl ethyl ether; 1,1,1-trifluoro-2-[1-(2,2,2-trifluoroethoxy)ethoxy]ethane; 1H,1H,2′H-perfluorodipropyl ether, 1,1,2,2-tetrafluoroethyl isobutyl ether; 34. The battery of claim 33 comprising one or more of 1,1,1,2,2,3,4,5,5,5-decafluoro-2-methoxy-4-(trifluoromethyl)pentane; 1-(ethoxy)nonafluorobutane having a mixture of n- and iso-butyl isomers; 2-(trifluoromethyl)-3-ethoxydodecafluorohexane; 3-methoxyperfluoro(2-methylpentane); heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether; 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether; methoxynonafluorobutane; ethoxynonafluorobutane; tris(2,2,2-trifluoroethyl)orthoformate; and di(2,2,2-trifluoroethyl)carbonate.

35. 18. The battery of claim 17, wherein the solvating solvent comprises a dialkoxyalkane, a dialkyl glycol ether, a disubstituted ester, a disubstituted carbonate, a trisubstituted phosphate, a disubstituted sulfone, and a tetrasubstituted silane, or any combination thereof.

36. 20. The battery of claim 17, further comprising a separator comprising a nonwoven fabric, a microporous film, a ceramic, or any combination thereof.

37. 1. A method of forming an electrolyte, comprising: dissolving lithium salts, including a first lithium salt and a second lithium salt, in a solvation solvent to form a solvation solvent-lithium salt solution; dissolving a diluent in the solvating solvent-lithium salt solution; further dissolving more of the first lithium salt or the second lithium salt to a concentration that exceeds the amount of the lithium salt soluble in the solvation solvent to form the electrolyte.

38. 38. The method of claim 37, wherein the lithium salt is present in the electrolyte below a saturation point of the lithium salt in the electrolyte.

39. 38. The method of claim 37, wherein the first lithium salt and / or the second lithium salt have different saturation points in the solvation solvent-lithium solution and the electrolyte.

40. 1. An electrolyte comprised of a solvation solvent, a diluent, and lithium salts, including a first lithium salt and a second lithium salt, wherein the electrolyte is a solution having a saturation point, the solvation solvent has a saturation point, the lithium salt is at least five times more soluble in the solvation solvent than in the diluent, and the first and second lithium salts are present in amounts below the saturation point of the electrolyte and above the saturation point of the solvation solvent.

41. 41. The electrolyte of claim 40, wherein the first and second lithium salts have different saturation points in the electrolyte and the solvation solvent, respectively.

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