Local high salt concentration electrolyte

Abstract

A battery includes 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 that is miscible with the solvating solvent. The solubility of the lithium salt in the solvating solvent is at least 5 times the solubility 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.

Description

Technical Field

[0001] The present disclosure relates to a liquid local high-salt concentration electrolyte for a battery. Background Art

[0002] New batteries utilize a cathode and a lithium metal anode to improve battery properties. When the battery is cycled, the stripping and deposition of lithium on the anode can lead to the formation of high-surface-area lithium and lithium dendrites. This effect can cause capacity fade of the battery. To help stabilize the battery, high-salt concentration electrolytes have been formulated, and such high-salt concentration electrolytes exhibit improved cycling performance. In these types of high-concentration electrolytes, all solvent molecules participate in the solvation of ions from the salt, and no free solvent molecules are produced. However, high-salt concentration electrolytes can have high viscosities, which limits their use in batteries.

[0003] Recently, in an attempt to remedy some of the drawbacks of high-salt concentration electrolytes, a diluting solvent has been added to the high-salt concentration electrolyte to form a local high-salt concentration electrolyte that has the desired viscosity while retaining some of the performance improvements of the high-concentration electrolyte (see, for example, U.S. Patents 11,094,966 and 10,367,232).

[0004] In an electrolyte containing a diluent, a lithium salt, and a solvating solvent, the lithium salt can be consumed as the battery is cycled, which can lead to the disruption of the solvation structure. As the solvation structure is disrupted, the solvating solvent can react at the electrodes. Therefore, what is needed is a new combination of diluent, solvating solvent, and salt that can extend the number of cycles before the electrolyte begins to decompose.

[0005] In addition, existing cathodes may lack the energy density required by the industry and may have harmful environmental effects due to the use of undesirable metals such as nickel and cobalt. Therefore, what is needed is a new cathode with high energy density and environmental friendliness, as well as an electrolyte that works with the cathode to manufacture a battery with high initial discharge capacity and excellent capacity retention. Summary of the Invention

[0006] The present disclosure provides a battery that includes a novel electrolyte formulation.

[0007] The battery can include an anode, a cathode, and / or a separator. In some instances, the cathode is a disordered rock salt structure. ]>

[0008] In one aspect, the present disclosure provides a battery that includes a cathode comprising a disordered rock-salt structure and an electrolyte. The electrolyte comprises a solvating solvent and a lithium salt soluble in the solvating solvent. The electrolyte includes a diluent miscible with the solvating solvent. The solubility of the lithium salt in the solvating solvent is at least 5 times the solubility in the diluent, and the solvating solvent and the diluent are present in the battery at a diluent ratio / solvating solvent ratio of 0.1 to less than 3.0.

[0009] In some aspects, the diluent may have a miscibility point in the solvating solvent, and the salt has a saturation point in the solvating solvent such that the saturation point of the salt in the solvating solvent is at least 5 times the miscibility point of the diluent in the solvating solvent. The diluent and the solvating solvent may be immiscible when the molar ratio of diluent / solvating solvent is 5 or greater. The diluent and the solvating solvent may be present at a molar ratio of 1.0 to 3.0. The combination of the lithium salt and the solvating solvent and the diluent may be present at a molar ratio of 1:2 or greater. The lithium salt may be present in the solvating solvent or the combination of solvating solvent / diluent at a concentration of about 0.5 M or greater up to the saturation point. The solvating solvent may include one or more of the following: dialkoxyalkanes, dialkyl glycol ethers, disubstituted esters, disubstituted carbonates, trisubstituted phosphates, disubstituted sulfones, and tetrasubstituted silanes. The solvating solvent may include a disubstituted carbonate.

[0010] In another aspect, the battery includes a cathode and an electrolyte. The electrolyte may include a solvating solvent and a lithium salt composed of a first lithium salt and a second lithium salt soluble in the solvating solvent. The second lithium salt is present at a concentration that may be less than or equal to the concentration of the first lithium salt. The electrolyte includes a diluent miscible at the molar concentration used in the solvating solvent for manufacturing the electrolyte. The solubility of the lithium salt in the solvating solvent may be at least 5 times the solubility in the diluent, and the solvating solvent and the diluent are generally present in the battery at a diluent / solvating solvent molar ratio of 0.1 to less than 3.0.

[0011] In some aspects, the first lithium salt and the second lithium salt can be present in the solvating solvent or in a combination of the solvating solvent / diluent at a molar ratio of 1 or greater or 2 or greater, equal to or less than their saturation point. The solvating solvent and the diluent can be immiscible when the molar ratio of the diluent / solvating solvent is 5.0 or greater. The concentration of the first lithium salt and the concentration of the second lithium salt can be within about 20% of each of their phase separations (saturation points) in the electrolyte. The battery can include an anode comprising one or more of: graphite, lithium, a lithium alloy, silicon, and a silicon alloy. The cathode can be charged to a voltage of 4.45 or higher. The cathode can comprise a disordered rock salt structure. The first lithium salt and the second lithium salt (total salt) can be present at a molar ratio of about 1:2.5 to about 1:5 with respect to the combination of the solvating solvent and the diluent. The first lithium salt and the second lithium salt can be present at a molar ratio of about 9:1 to about 1:1.

[0012] In some aspects, the first lithium salt or the second lithium salt may include one or more of the following: lithium bis(oxalato)borate (LiBOB), lithium bis(pentafluoroethylsulfonyl)imide (Li-BETI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium trifluoromethanesulfonate (LiTriflate), lithium hexafluoroarsenate (LiAsF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium nitrate (LiNO3), LiN(SO2CF3)2, LiN(SO2F)2, LiCF3SO3, LiClO4, lithium difluoro(oxalato)borate anion salt (LiDFOB), LiI, LiBr, LiCl, LiOH, and LiSO4. The battery may have a capacity retention of 80% at about 100 cycles or more. The battery may have a capacity of about 180 mAh / g or higher. The diluent may include a fluorinated ether, the fluorinated ether including one or more of the following: 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',2,2',3,3',4,5,5',5'-decafluoro-2-methoxy-4-(trifluoromethyl)pentane; 1-(ethoxy)nonafluorobutane having a mixture of n-butyl isomers and isobutyl 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 bis(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.

[0013] 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 further comprises dissolving more of the first lithium salt or the second lithium salt to a concentration that exceeds the amount of lithium salt that is soluble in the solvating solvent present to form an electrolyte.

[0014] In some aspects, the first lithium salt and / or the second lithium salt may be present in the electrolyte at less than the saturation point of the salt in the electrolyte. The first lithium salt and / or the second lithium salt may have different saturation points in the solvating solvent-lithium solution and in the electrolyte.

[0015] In another aspect, the present disclosure provides an electrolyte comprising a solvating solvent, a diluent, and a lithium salt, the lithium salt comprising 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 may be dissolved in the solvating solvent at a solubility of at least 5 times or more. The first lithium salt and / or the second lithium salt may be present in an amount less than their saturation point in the electrolyte and greater than the saturation point of the solvating solvent. The first lithium salt and / or the second lithium salt may have different saturation points in the electrolyte and in the solvating solvent.

[0016] The present disclosure has found that adding a second lithium salt to a locally high salt concentration electrolyte can provide a battery with increased capacity retention. The first lithium salt and the second lithium salt may have different anion structures and thus may be consumed at different rates. This can be advantageous because the composition and structure of the locally high concentration electrolyte can be maintained over a longer cycle life, as measured by a cycle retention of 80% of the maximum discharge capacity.

[0017] Additionally, the present disclosure has determined that using a locally high concentration electrolyte and a disordered rock salt cathode can provide a battery with high charge capacity and capacity retention. The disordered rock salt cathode may have a high energy density and may not contain some of the expensive metals used in other batteries, such as nickel and cobalt. Batteries without nickel and cobalt may be more desirable because they are more environmentally friendly and have lower production costs. Thus, a cheaper and more environmentally friendly disordered rock salt cathode can be used in the cathode, and the properties of the disordered rock salt cathode are similar to or better than those of conventional cathodes (such as nickel-based cathodes or cobalt-based cathodes). BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figures 1A to 1B Shows the discharge capacity and capacity retention of various solvating solvents used with a disordered rock salt cathode.

[0019] Figures 2A to 2B Shows the discharge capacity and capacity retention of a single lithium salt electrolyte compared to a dual lithium salt electrolyte.

[0020] Figures 3A to 3B Shows the discharge capacity and capacity retention of various diluents used with a disordered rock salt cathode. Detailed Description

[0021] The following definitions apply to some aspects described in connection with some embodiments of the present invention. These definitions may equally be extended herein. Each term is further explained and illustrated by description, drawings, and examples. Any interpretation of the terms in this specification should consider the complete description, figures, and examples provided herein.

[0022] Definitions of specific functional groups and chemical terms are described in more detail below. For the purposes of this disclosure, chemical elements are identified according to the CAS version of the Periodic Table of the Elements on the inside cover of the Handbook of Chemistry and Physics, 75th Edition, and specific functional groups are generally defined as described therein. Additionally, general principles of organic chemistry and specific functional moieties and reactivity are described in Organic Chemistry, Thomas Sorrell, University Science Books, Sausalito, 1999; Smith and March March’s Advanced Organic Chemistry, 5th Edition, John Wiley & Sons, Inc., New York, 2001; Larock, Comprehensive Organic Transformations, VCH Publishers, Inc., New York, 1989; 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.

[0023] As used herein, the terms "halo" and "halogen" refer to atoms selected from fluorine (fluoro, -F), chlorine (chloro, -Cl), bromine (bromo, -Br), and iodine (iodo, -I). As used herein, the term "aliphatic group" means a hydrocarbon moiety that can be straight-chain (i.e., unbranched), branched, or cyclic (including fused, bridged, and spiro-fused polycyclic) and can be fully saturated or can contain one or more unsaturated units but is not aromatic. The aliphatic group can contain 1 - 40 carbon atoms, 1 - 20 carbon atoms, 2 - 20 carbon atoms, 1 - 12 carbon atoms, 1 - 8 carbon atoms, 1 - 6 carbon atoms, 1 - 5 carbon atoms, 1 - 4 carbon atoms, 1 - 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. The aliphatic group can be unsubstituted or substituted. Substituted means that one or more C atoms or H atoms are replaced by oxygen, boron, sulfur, nitrogen, phosphorus, or halogen. Typically, one to six carbon atoms can be independently replaced by the foregoing, especially oxygen, sulfur, or nitrogen. The aliphatic group can have one or more "halo" and "halogen" atoms selected from fluorine (fluoro, -F), chlorine (chloro, -Cl), bromine (bromo, -Br), and iodine (iodo, -I).

[0024] As used herein, "phase" means that one or more compounds are physically distinct from another group of compounds and can be mechanically separated.

[0025] "Miscible" means that two or more compounds form a solution when brought into contact. The compounds can be completely miscible at any molar ratio (moles / moles), but in many cases, the compounds are miscible below the solubility limit of one compound in the other, and each compound is typically a liquid solvent at ambient conditions (about 20 °C and about 1 atmosphere of pressure), but in some cases, one or more of the compounds (e.g., the solvent) can be a solid at room temperature, and the solid is soluble in the liquid solvent at room temperature.

[0026] "Immiscible" means that two or more compounds phase-separate at a molar ratio (moles / moles) greater than the miscible molar ratio (i.e., greater than the solubility limit defined by the saturation point of one compound in the other).

[0027] "Miscibility point" refers to the maximum molar ratio (moles / moles) at which a compound (e.g., a solvent) can be miscible with another compound to form a homogeneous solution shortly before phase separation, which is analogous to the saturation point of a solid dissolved in a liquid.

[0028] "Saturation point" means the molar ratio (moles / mole) of a compound (e.g., a salt) present in a solvent, i.e., the maximum amount in moles of the compound that can be dissolved in the solvent before phase separation at equilibrium.

[0029] A "saturated solution" contains an amount of soluble compound greater than the saturation point such that an amount of the soluble compound precipitates out.

[0030] "Soluble" means that a solid compound is soluble in a solvent or a solution of the solvent at or below the saturation point, e.g., a salt is soluble in a solution of the solvent.

[0031] If not otherwise specified, any characteristic or property can be determined by standard laboratory practices used to determine such property or characteristic. For example, if there is no generally applicable boiling point in the literature, the boiling point can be determined by ASTM D86. "Solubility" can be determined by the "shake flask" method according to the guidelines provided in OECD, Paris, 1981, Test Guideline 107, Decision of the Council C(81)30 final. If there is no generally applicable "viscosity" in the literature, the "viscosity" can be determined by ATSM D445.

[0032] A battery consists of a cathode, an anode, a separator, and an electrolyte. It should be understood that each of these components can be connected to or included in other common components of the battery, such as current collectors coated with the anode and cathode and a battery container that encloses the battery components electrically connected to the battery. For example, the current collector can be any suitable metal (e.g., Al, an alloy of Al and Cu, and an alloy of Cu) foil, sheet, etc., such as a metal foil that can be further coated with a conductive material (such as carbon), including those described in U.S. Patent 9,172,085, which is incorporated herein by reference.

[0033] The cathode can contain any material sufficient to have a desired discharge capacity and charge retention rate when used with the anode and a locally high-concentration electrolyte. Examples of suitable cathode materials can include phosphates, fluorophosphates, fluorosulfates, fluorosilicates, spinels, lithium-rich layered oxides, and composite layered oxides. Additional examples of suitable cathode materials can 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.

[0034] In a disordered rock salt cathode, both lithium and transition metals occupy a cubic close-packed lattice of octahedral sites. In the electrochemical reaction, lithium diffusion occurs by lithium jumping from one octahedral site via an intermediate tetrahedral site to another octahedral site. Lithium at the intermediate tetrahedral site is the activated state in lithium diffusion. The activated tetrahedral lithium ion shares faces with the following four octahedral sites: (i) the site previously occupied by the lithium ion itself; (ii) the vacant site into which the lithium ion will enter; (iii and iv) two sites that can be occupied by lithium, transition metal, or vacancy.

[0035] The composition can be expressed as

[0036] Li x M’ y M z O 2-(a+b) F a Z b

[0037] where 1.0 < x < 1.75; 0.01 < y < 0.55; 0.1 < z < 1; 0 ≤ (a + b) < 0.7; (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; Z is one or more of P, N, and S.

[0038] The amounts of F and Z can be the majority or minority of the anions (i.e., O, F, and one or more of P, S, and N). For example, (a + b) is 0.05 to 1.5, 1, 0.95, 0.8, 0.65, 0.5). It may be desirable for a to be 0.05 to 0.25. Z can be any combination of P, N, S, or just one of them. When two or more are present, the ratio between P, N, and S can be any useful ratio, depending on the property sought. For example, when it is desired to lower the redox potential, it may be necessary to have S present. It may also be desirable for S to be the majority of P, S, and N present in the composition.

[0039] The composition can have any desired amount of Li of 1 or more, but it is desired that the Li represented by x be at least 1.1, 1.15, 1.2 to 1.65, 1.5, or 1.4.

[0040] The cation of the composition can be the metals described, but ideally, at least one metal represented by M consists of one or more of Ti, Mn, Fe, Co, V, Cr, Ni, and Cu. It may be desirable for M to consist of Ti and Mn. For example, the composition can be a composition in which M' consists of Nb. When Nb is present, it may be desirable for M to consist of Mn. For example, M′ can be Nb and M can be Mn. When Nb and Mn are present with or without other metals, they can be present in a Mn / Nb ratio of 1 to 10, 1 to 5, 2 to 10, or 2 to 5 by mole.

[0041] Disordered rock salt can be made by any suitable method such as those known in the art for making disordered rock salt. Exemplary methods are described in U.S. Patent Nos. 10,280,092, 10,978,706, and ACS Appl Mater Interfaces. October 2, 2019; 11(39):35777 - 35787, each of which is incorporated herein by reference.

[0042] For example, disordered rock salt desirably consists of aggregates of micron - sized clusters or sub - micron - sized particles, which can be used to increase the capacity and energy density of the battery cathode. The micron - sized clusters are also referred to herein as secondary particles. The secondary particles desirably have an average particle size (e.g., diameter) in the micron range, such as between 1 micron and 20 microns. 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 prior to the secondary particles, and the secondary particles are aggregates of the primary particles. The primary particles have an average particle size (e.g., diameter) in the nano range, such as less than 400 nanometers. The sub - micron primary particles of the disordered rock salt material can provide desirable conductivity, while the micron - sized secondary particles of the disordered rock salt material produce a high electrode energy density.

[0043] Alternatively, the cathode of the battery can consist of any suitable lithium metal phosphate (such as those known in the art). Exemplary lithium metal phosphates include those consisting of manganese, iron, or a combination thereof. The lithium metal phosphate can be doped with a small amount (5 wt% or less) of other metals.

[0044] The cathode can also contain other cathode components, such as a binder and a conductive additive. The binder can be any suitable binder known in the art and can include, for example, carboxymethyl cellulose (CMC), styrene - butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or a mixture of two or more of them. Ideally, the cathode consists of PVDF. The conductive additive can be graphite, carbon black, carbon nanotubes, graphene, and carbon fibers.

[0045] The amount of other cathode components can be any suitable amount, but is generally from about 20 volume % or 10 volume % to about 0.1 volume %, 0.5 volume % or 1 volume % of the cathode (i.e., lithium metal phosphate and other cathode components).

[0046] The anode can include any material sufficient to act as an anode with the selected cathode and the locally high concentration electrolyte. The anode can comprise one or more of the following: graphite, lithium, lithium alloys, silicon, and silicon alloys. When the anode is a lithium alloy or lithium metal, the electrolyte can be formulated to reduce the formation of additional lithium surface area or lithium dendrites during battery cycling. Examples of suitable anode materials can include conventional anode materials used in lithium ion batteries, such as lithium, graphite (“Li x C6”), and other carbon, silicon, or oxide-based anode materials.

[0047] The anode can be composed of graphitic carbon. The graphitic carbon can be any carbon capable of intercalating lithium, and it should be understood that carbon exhibiting short-range order but limited long-range order and presenting amorphous by X-ray diffraction can be used. For example, the graphitic carbon can be synthetic graphite or natural graphite having a purity sufficient for use in a lithium ion battery, which generally requires a purity of at least about 99.5%, 99.9% or 99.95%. For example, the graphitic carbon can be spherical graphite, and it should be understood that such graphite is not a perfect sphere and can be oval in nature but not flake-like. Spherical graphite generally has a high purity such as at least 99.95% pure, but can also be composed of a small amount of oxides (such as silica, titanium dioxide, and zirconia or other materials capable of intercalating lithium, but the amount of these materials present is less than 5 volume % or 1 volume % of the cathode). The spherical graphite can be artificial graphite or purified natural graphite. Examples of useful spherical graphite are described in U.S. Patent Publication 2016 / 0141603 and U.S. Patent 9,276,257, each of which is incorporated herein by reference. Examples of suitable commercially available spherical graphite include those obtained from Syrah Resources, Magnis Resources, Northern Graphite, FocusGraphite, and Graphite One.

[0048] The separator may have one or more layers that can be bonded together. Examples of suitable separators include polyimide, polyolefins (such as polypropylene), polyethylene terephthalate, ceramic-coated polyolefins, cellulose, or mixtures of two or more of them. Such materials may be in the form of microfibers or nanofibers. The separator may comprise a combination of microfibers and nanofibers. In certain embodiments, the separator comprises polyethylene terephthalate microfibers and cellulose nanofibers. Illustrative examples of separators that may be useful include those described in U.S. Patent 8,936,878, which is incorporated herein by reference. Additional examples of separators include those obtained from Dreamweaver International (Greer S.C). Generally, the separator thickness is at most 250 microns to at least about 5 microns or 10 microns.

[0049] The electrolyte includes a diluent, a solvating solvent, and a lithium salt. The diluent and the solvating solvent may be in contact in a miscible molar ratio as described below.

[0050] The lithium salt may be any salt that is sufficiently surrounded by the solvation structure of the solvating solvent and / or diluent in the electrolyte. The solubility of the lithium salt in the solvating solvent relative to its solubility in the diluent may permit the diluent and the solvating solvent to be miscible in a miscible molar ratio, thereby improving the discharge capacity and capacity retention. For example, the solubility of the lithium salt in the diluent may be greater than zero. The solubility of the lithium salt in the solvating solvent may be about 1 M or greater, about 3 M or greater, or about 5 M or greater. The solubility of the lithium salt in the solvating solvent may be about 20 M or less, about 15 M or less, or about 10 M or less. The solubility of the lithium salt in the solvating solvent 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 the solubility of the diluent in the solvating solvent. 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 the diluent, i.e., the concentration is about 1 M or greater, about 2 M or greater, or about 5 M or greater. 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 the diluent, i.e., the concentration is about 20 M or less, about 10 M or less, or about 7 M or less.

[0051] The concentration at which the lithium salt reaches saturation in the electrolyte can vary depending on the miscible molar ratio of the diluent / 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 less, about 2.0 M or less, or about 1.5 M or less. 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 less, about 1:5 or less, or about 1:4 or less.

[0052] The electrolyte can contain multiple lithium salts, which can be dissolved in the diluent / solvating solvent in a miscible molar ratio in a combined manner. The electrolyte can contain a single salt, or the electrolyte can contain two or more, three or more, four or more, or multiple salts. When using a combination of lithium salts, the lithium salts can each have different saturation points in the solvating solvent, diluent, or a combination of both in the electrolyte solution. For example, the saturation point of the first lithium salt in the solvating solvent, diluent, or a combination of both in the electrolyte solution can be about 1%, 5%, or 10% to about 50%, 35%, or 20% higher or lower than the saturation point of the second lithium salt in the same solution.

[0053] When using a combination of lithium salts, the lithium salts can each be different from one another. It has been found that using different salts can cause the anode, cathode, or solid electrolyte interphase (SEI) layer to be consumed at different rates, and different saturation points in the solvating solvent, diluent, or a combination of both can contribute to achieving this. When using two or more lithium salts, as the battery cycles and the lithium salts are consumed, one lithium salt in the solvation structure can replace another, thereby maintaining the solvation structure and keeping the electrolyte stable. Ideally, for example, it has been found that a combination of salts (such as LiFSI and LiBF4) improves the capacity retention of a battery composed of a high-energy density cathode (such as a cathode composed of disordered rock salt).

[0054] The lithium salt can include lithium bis(oxalato)borate (LiBOB), lithium bis(pentafluoroethylsulfonyl)imide (Li-BETI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium trifluoromethanesulfonate (LiTriflate), lithium hexafluoroarsenate (LiAsF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium nitrate (LiNO3), LiN(SO2CF3)2, LiN(SO2F)2, LiCF3SO3, LiClO4, lithium difluoro(oxalato)borate anion salt (LiDFOB), LiI, LiBr, LiCl, LiOH, and LiSO4, or any combination thereof.

[0055] In some instances, another salt can be included in the electrolyte, such as another alkali metal salt, 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.

[0056] The diluent and the solvating solvent can be in contact in a miscible molar ratio in the electrolyte. An amount of the diluent can be used such that the diluent and the solvating solvent are miscible when the lithium salt is dissolved in the solvating solvent. For example, in the presence of the lithium salt, the diluent and the solvating solvent can become immiscible when the molar ratio of diluent / solvating solvent is about 0.5 or greater, about 1.5 or greater, about 2.0 or greater, 2.5 or greater, about 3.5 or greater, or about 5.0 or greater, and become substantially completely miscible when the molar ratio of diluent / solvating solvent is about 20 or less, or about 10 or less.

[0057] The diluent can serve to reduce the viscosity of the electrolyte while maintaining the high salt concentration property required for the battery. For example, when the diluent is added to a solution of the solvating solvent and the lithium salt, the viscosity of the solution can be reduced while maintaining or achieving favorable properties of the solution. Ideally, the viscosity of the diluent is less than the viscosity of the solvating solvent, and ideally, is at least 5%, 10%, 25%, or 50% less than the viscosity 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 rate. For example, the viscosity of the solution can be about 0.1 cP or greater, about 3 cP or greater, or about 5 cP or greater. The viscosity of the solution can be about 15 cP or less, about 10 cP or less, or about 7 cP or less.

[0058] The diluent can have any level of miscibility with the solvating solvent sufficient for a local high concentration electrolyte. For example, the diluent can be completely miscible, or can have a miscibility point of at most 10 (moles diluent / moles solvating solvent), about 5, or about 3 to at least about 0.5 or about 1 in the solvating solvent. It has been unexpectedly found that in some cases, when the diluent is used at a molar ratio less than the miscibility point of the diluent in the solvating solvent, but within 50%, 25%, or 10% of that miscibility point, a diluent with limited miscibility in the solvating solvent can achieve improved discharge capacity and capacity retention. By way of example, the diluent can have a miscibility point between a molar ratio of about 2 and a molar ratio of about 5 or between a molar ratio of about 2 and a molar ratio of about 3, and the molar ratio of the diluent to the solvent in the electrolyte is equal to the miscibility point of the diluent in the solvating solvent or within 50%, 25%, or 10% of that miscibility point. The miscibility point of the diluent in the solvating solvent can be 1 / 15 to 1 / 3, 1 / 10 to 1 / 3, 1 / 8 to 1 / 3, 1 / 15 to 1 / 5, 1 / 10 to 1 / 5, or 1 / 8 to 1 / 5 of the saturation point of the lithium salt in the solvating solvent.

[0059] The miscibility of the diluent in the solvent can change depending on the presence of the lithium salt dissolved in the solvating solvent. For example, in the presence of the lithium salt, the diluent can have a higher or lower miscibility with the solvating solvent, which is equal to or less than the saturation point in the solvating solvent or solution. The miscibility of the diluent in the solvating solvent in which the salt is dissolved can be 1% to 20%, 10%, or 5% of the miscibility point of the diluent in the pure solvating solvent, where it is desirable for the diluent to have a higher miscibility in the solvating solvent in the presence of the salt.

[0060] The miscibility of the diluent in the solvating solvent can be different from the solubility of the lithium salt in the solvating solvent. For example, the solubility of the lithium salt in the solvating solvent on a molar basis can be about 3 times, about 5 times, or about 7 times to about 10 times, about 13 times, or about 15 times the miscibility of the diluent in the solvating solvent. By way of example, it can be desirable for the diluent to have a miscibility point with a molar ratio of 2 or 3 to 5, and the amount of diluent present is within 10%, 25%, or 50% of the miscibility point, and the amount of salt that can be dissolved in the diluent is 1 / 10 to 1 / 5, 1 / 9 to 1 / 5, 1 / 8 to 1 / 5, 1 / 10 to 1 / 6, 1 / 9 to 1 / 6, or 1 / 8 to 1 / 6 of the amount of salt that can be dissolved in the solvating solvent.

[0061] The structure of the diluent can alter the miscibility of the solvating solvent and the diluent. For example, the miscibility of a diluent having a straight-chain alkyl group in the solvating solvent can be different from that of a diluent having a branched-chain alkyl group. For example, compared to the case where the diluent contains only straight-chain alkyl groups, when branched-chain alkyl groups are present in the diluent, the solvating solvent can be immiscible with the diluent at a lower molar ratio while still achieving the desired discharge capacity and capacity retention rate.

[0062] The electrolyte can include a combination of diluents having different substitutions. For example, a combination of diluents containing straight-chain alkyl groups, branched-chain alkyl groups, or both can provide different miscible molar ratios with the solvating solvent while achieving the desired discharge capacity and capacity retention rate.

[0063] The electrolyte can contain a variety of different diluents that are sufficient to be miscible with the solvating solvent and / or adjust the viscosity of the electrolyte. For example, the electrolyte can contain one or more, two or more, three or more, four or more, or a plurality of diluents.

[0064] The diluent can include one or more fluorinated ethers. The fluorinated ether can be a compound comprising a combination of an ether group, a fluorine atom, and carbon atoms that are fully saturated with hydrogen.

[0065] Examples of fluorinated ethers can include one or more of the following: 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 having a mixture of n-butyl isomers and isobutyl 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 (TFTFE); methoxynonafluorobutane (MOFB); ethoxynonafluorobutane (EOFB); tris(2,2,2-trifluoroethyl) orthoformate; and bis(2,2,2-trifluoroethyl) carbonate.

[0066] The solvating solvent can function to provide a solvation structure around the anion and / or cation of the lithium salt. To achieve the desired amount of salt dissolution in the electrolyte (where some salts can dissolve in the diluent, which can achieve improved battery performance), the lithium salt can first be dissolved in the solvating solvent at or near the saturation point to form a solvating solvent-salt solution. Then the diluent can be added to the solvating solvent-salt solution to form the electrolyte. Additional salt can be added until the saturation point of the salt in the electrolyte is reached or approached.

[0067] Since some lithium salts are soluble in the diluent, after adding the diluent to the solution of the solvating solvent and the lithium salt, an additional amount of lithium salt can be added until the saturation point of the solution is reached or is less than the saturation point of the solution. For example, the amount of salt can be equal to any useful concentration, but is typically substantially equal to or slightly less than the saturation point, but can be adjusted according to, for example, the expected operating conditions of any 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). The additional lithium salt can be added to the combination of the diluent and the solvating solvent until the saturation point of the solvating solvent is reached, while the diluent and the solvating solvent are at the 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, based on the saturation point of the lithium salt in the solvating solvent alone, the amount of salt in the solution can exceed the saturation point of the solvating solvent alone by about 1% to about 25%, about 1% to about 10%, about 5% to about 25%, or about 5% to about 10%. When considering viscosity parameters or battery performance, an amount of lithium salt less than the saturation of the solvating solvent-diluent solution can be desired.

[0068] In some instances, the diluent and the solvating solvent can first be contacted, and then the lithium salt can be contacted with the combination of the diluent and the solvating solvent in an amount equal to or less than the saturation point of the combination of the diluent and the solvent. If the lithium salt contacts the solvating solvent, the diluent, or both of them in an amount greater than the saturation point of the solvating solvent, the diluent, or both of them, thereby forming a saturated solution, the precipitated lithium salt can be removed from the saturated solution. If the lithium salt contacts the solvating solvent in an amount greater than the saturation point of the solvating solvent, the precipitated lithium salt can be removed before or after adding the diluent.

[0069] The solvating solvent has a different solubility of the lithium salt than the solubility of the lithium salt in the diluent. When the lithium salt is present at or below the saturation point, the solubility of the lithium salt in the diluent and the solvating solvent can affect the miscible molar ratio of the diluent / solvating solvent. For example, compared to the case where no lithium salt is present, when the lithium salt is present at the saturation point in the solution of the solvating solvent and the diluent, the miscible molar ratio of the diluent / solvating solvent can be higher or lower.

[0070] The solvating solvent may be included based on the lithium salt present at or below the saturation point such that the lithium salt can immobilize the solvating solvent and reduce its ability to form the SEI layer. The diluent and the solvating solvent may be in contact at an equal to, greater than, or less than the miscible molar ratio. The diluent and the solvating solvent may be in contact at an equal to or less than the miscible molar ratio to provide excellent discharge capacity and / or capacity retention. In some examples, when the solvating solvent, the diluent, and the lithium salt are in contact, the lithium salt may be present at a concentration equal to or less than the saturation point in the miscible molar ratio of the diluent / solvating solvent to improve the discharge capacity and / or capacity retention of the battery.

[0071] The solvating solvent may have a saturation point for any salt that can be used to manufacture the electrolyte. The saturation point of the salt in the solvating solvent may 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 may be any viscosity that can be used to manufacture the battery. The viscosity of the solvating solvent at room temperature (about 20 °C) may be 1 cP or greater, 20 cP or greater, or 50 cP or greater to 200 cP or less, 100 cP or less, or 200 cP or less. Note that in some cases the solvating solvent may be a solid at room temperature. In such cases, solubilization of the salt causes the solvent to become liquid due to the depression of the freezing point.

[0072] The solvating solvent may be any solvent or combination of solvents that is miscible with the diluent and can fully dissolve the lithium salt in the presence or absence of the diluent. The electrolyte may include a plurality of solvating solvents sufficient to form the desired solvation around the cation and / or anion of the lithium salt. For example, the electrolyte may contain one or more, two or more, three or more, four or more, or a plurality of solvating solvents. The solubility of each salt in the solvating solvent and / or the diluent may be substantially the same or different. For example, it may be desirable for one salt to have a greater solubility in the diluent (e.g., 5%, 10%, or 20% greater than the solubility of other salts), which may be desirable for forming a favorable SEI layer. In some examples, the solvating solvent may include one or more of the following: dialkoxyalkanes, dialkyl glycol ethers, disubstituted esters, disubstituted carbonates, trisubstituted phosphates, disubstituted sulfones, and tetrasubstituted silanes.

[0073] The dialkoxyalkane may include a pair of alkyl ethers bonded by a C 1-12 alkane group that may be branched or straight-chain. For example, the dialkoxyalkane may include one or more of the following: dimethoxyethane (DME), diethoxyethane (DEE), 1,2-dimethoxypropane (DMP), and the dialkoxyalkane may have the following structure:

[0074]

[0075] Each R1 can independently include a C that can be straight-chain or branched-chain 1-12 alkyl group, or any combination thereof.

[0076] Wherein R2 can include a C that can be straight-chain or branched-chain 1-12 alkyl group, or any combination thereof.

[0077] Wherein n is an integer from 1 to 5.

[0078] The dialkyl glycol ether can include a series of three ether groups separated by an alkyl chain that can be straight-chain or branched-chain. Examples of the dialkyl glycol ether can include 1,2-diethylene glycol isopropyl methyl ether (DEGIM), diethylene glycol butyl methyl ether (DEGBM), or any combination thereof. The dialkyl glycol can have the following structure:

[0079]

[0080] Each R1 can independently include a C that can be straight-chain or branched-chain 1-12 alkyl group, or any combination thereof.

[0081] Each R2 can independently include a C that can be straight-chain or branched-chain 1-12 alkyl group, or any combination thereof.

[0082] Each n is an integer from 1 to 5.

[0083] The disubstituted ester can include an ester substituted at the carbon atom of the carbonyl group or the oxygen atom of the hydroxyl group by one or more groups including hydrogen, C 1-12 alkyl, C 1-12 aryl, or any combination thereof. Examples of the disubstituted ester can include ethyl difluoroacetate, ethyl propionate, or any combination thereof. The disubstituted ester can have the following structure:

[0084]

[0085] Each R1 can independently include a hydrogen atom, a C that can be straight-chain or branched-chain 1-12 alkyl group, a heteroalkyl group that can be straight-chain or branched-chain, or any combination thereof. The combination of two R1s can form a cyclic alkyl ring, which can optionally contain one or more heteroatoms.

[0086] The disubstituted carbonate can be independently substituted at each of the carbon atoms. The disubstituted carbonate can include dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, or any combination thereof. The disubstituted carbonate can have the following structure:

[0087]

[0088] Each R1 can independently include a hydrogen atom, a C alkyl group which can be straight-chain or branched-chain, a heteroalkyl group which can be straight-chain or branched-chain, or any combination thereof. The combination of two R1s can form a cyclic alkyl ring which can optionally contain one or more heteroatoms. 1-12 The combination of two R1s can form a cyclic alkyl ring which can optionally contain one or more heteroatoms.

[0089] The trisubstituted phosphate can be substituted at each of the single-bond oxygen atoms. The trisubstituted phosphate can include trimethyl phosphate, triethyl phosphate, or any combination thereof. The trisubstituted phosphate can have the following structure:

[0090]

[0091] Each R1 can independently include a hydrogen atom, a C alkyl group which can be straight-chain or branched-chain, a heteroatom, a heteroalkyl group, or any combination thereof. 1-12 The combination of two R1s can form a cyclic alkyl ring which can optionally contain one or more heteroatoms.

[0092] Each R2 can independently include a hydrogen atom, a C alkyl group which can be straight-chain or branched-chain, or any combination thereof. 1-12 The combination of two R1s can form a cyclic alkyl ring which can optionally contain one or more heteroatoms.

[0093] The disubstituted sulfone can be substituted at the sulfur atom by one or more groups including hydrogen, C alkyl, C aryl, or any combination thereof. The disubstituted sulfone can include sulfolane, methyl ethyl sulfone, methyl isopropyl sulfone, or any combination thereof. The disubstituted sulfone can have the following structure: 1-12 alkyl, C 1-12 aryl, or any combination thereof. The disubstituted sulfone can include sulfolane, methyl ethyl sulfone, methyl isopropyl sulfone, or any combination thereof. The disubstituted sulfone can have the following structure:

[0094]

[0095] Each R1 can independently include a hydrogen atom, a C alkyl group which can be straight-chain or branched-chain, a heteroalkyl group which can be straight-chain or branched-chain, or any combination thereof. The combination of two R1s can form a cyclic alkyl ring which can optionally contain one or more heteroatoms. 1-12 The combination of two R1s can form a cyclic alkyl ring which can optionally contain one or more heteroatoms.

[0096] The tetrasubstituted silane can be substituted at the silicon atom and / or at each oxygen atom. The tetrasubstituted silane can include triethoxymethylsilane, trimethoxymethylsilane, or any combination thereof. The tetrasubstituted silane can have the following structure:

[0097]

[0098] Each R3 can independently include a hydrogen atom, a C alkyl group which can be straight-chain or branched-chain, 1-12An alkyl group, a heteroatom, a heteroalkyl group, which may be straight-chain or branched-chain C 1-12 an alkoxy group, a heteroatom, a heteroalkyl group, or any combination thereof.

[0099] The discharge capacity or capacity retention rate that the battery can have depends at least in part on the molar ratio of the selected solvent to the diluent and the solvating solvent. For example, the structure of the diluent containing a branched or straight-chain alkyl group can change the discharge capacity or capacity retention rate. In other examples, decreasing or increasing the molar ratio of the diluent / solvating solvent based on the miscibility of the solvent or the structure of the diluent can change the discharge capacity or capacity retention rate. The battery can have a discharge capacity of about 120 mAh / g or higher, about 140 mAh / g or higher, or about 160 mAh / g or higher. The battery can have a discharge capacity of about 220 mAh / g or lower, about 200 mAh / g or lower, or about 180 mAh / g or lower. The battery can have a capacity retention rate of 80% at about 40 cycles or more, about 90 cycles or more, or about 140 cycles or more. The battery can have a capacity retention rate of 80% at about 200 cycles or less, about 180 cycles or less, or about 160 cycles or less.

[0100] Enumerated embodiments

[0101] The following embodiments are for illustrative purposes and do not unduly limit the scope of the present disclosure.

[0102] Embodiment 1. A battery, comprising:

[0103] a cathode comprising a disordered rock salt structure; and

[0104] an electrolyte comprising:

[0105] a solvating solvent;

[0106] a lithium salt soluble in the solvating solvent; and

[0107] a diluent miscible with the solvating solvent,

[0108] the solubility of the lithium salt in the solvating solvent is at least 5 times the solubility in the diluent, and the solvating solvent and the diluent are present in the battery at a diluent ratio / solvating solvent ratio of 0.1 to less than 3.0.

[0109] Embodiment 2. The battery according to Embodiment 1, wherein the diluent has a miscibility point in the solvating solvent, and the salt has a saturation point in the solvating solvent such that the saturation point is at least 5 times the miscibility point.

[0110] Embodiment 3. The battery according to Embodiment 1 or Embodiment 2, wherein the diluent and the solvating solvent are immiscible when the molar ratio of diluent / solvating solvent is 5 or greater.

[0111] Embodiment 4. The battery according to 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.

[0112] Embodiment 5. The battery according to any one of Embodiments 1 to 4, wherein the lithium salt is present in a molar ratio of 1:2 or greater with the combination of the solvating solvent and the diluent.

[0113] Embodiment 6. The battery according to any one of Embodiments 1 to 5, wherein the lithium salt is present at a concentration of about 0.5 M or greater, at the saturation point, in the solvating solvent or in the combination of the solvating solvent / diluent.

[0114] Embodiment 7. The battery according to any one of Embodiments 1 to 6, wherein the solvating solvent comprises one or more of the following: dialkoxyalkanes, dialkyl glycol ethers, disubstituted esters, disubstituted carbonates, trisubstituted phosphates, disubstituted sulfones, and tetrasubstituted silanes.

[0115] Embodiment 8. The battery according to any one of Embodiments 1 to 7, wherein the solvating solvent comprises a disubstituted carbonate.

[0116] Embodiment 9. A battery comprising:

[0117] a cathode; and

[0118] an electrolyte comprising:

[0119] a solvating solvent;

[0120] a lithium salt soluble in the solvating solvent, comprising a first lithium salt and a second lithium salt, the second salt being present at a concentration less than or equal to the concentration of the first salt;

[0121] a diluent miscible in the solvating solvent,

[0122] the solubility of the lithium salt in the solvating solvent is at least 5 times the solubility in the diluent, and the solvating solvent and the diluent are present in the battery at a diluent ratio / solvating solvent ratio of 0.1 to less than 3.0.

[0123] Embodiment 10. The battery according to Embodiment 9, wherein the first lithium salt and the second lithium salt are present at a molar ratio of 1 or greater, at a point equal to or less than the saturation point, in the solvating solvent or in the combination of the solvating solvent / diluent.

[0124] Embodiment 11. The battery according to Embodiment 10, wherein the first lithium salt and the second lithium salt are present in the solvating solvent or the combination of the solvating solvent / diluent at a molar ratio of 2 or greater and at or below the saturation point.

[0125] Embodiment 12. The battery according to any one of the preceding embodiments, wherein the solvating solvent and the diluent are immiscible when the molar ratio of diluent / solvating solvent is 5.0 or greater.

[0126] Embodiment 13. The battery according to Embodiment 10, wherein the concentration of the first lithium salt and the concentration of the second lithium salt are within about 20% of the phase separation in the electrolyte.

[0127] Embodiment 14. The battery according to any one of the preceding embodiments, further comprising an anode comprising one or more of: graphite, lithium, lithium alloy, silicon, and silicon alloy.

[0128] Embodiment 15. The battery according to any one of Embodiments 9 to 14, wherein the cathode is rechargeable to a voltage of 4.45 or higher.

[0129] Embodiment 16. The battery according to any one of Claims 9 to 15, wherein the cathode comprises a disordered rock salt structure.

[0130] Embodiment 17. The battery according to any one of Embodiments 9 to 16, wherein the first lithium salt and the second lithium salt are present in a molar ratio of about 1:2.5 to about 1:5 relative to the combination of the solvating solvent and the diluent.

[0131] Embodiment 18. The battery according to any one of Embodiments 9 to 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.

[0132] Embodiment 19. The battery according to any one of Embodiments 9 to 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 (LiBF4), lithium trifluoromethanesulfonate (LiTriflate), lithium hexafluoroarsenate (LiAsF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium hexafluorophosphate (LiPF6), lithium nitrate (LiNO3), LiN(SO2CF3)2, LiN(SO2F)2, LiCF3SO3, LiClO4, lithium difluoro(oxalato)borate anion salt (LiDFOB), LiI, LiBr, LiCl, LiOH, and LiSO4, or any combination thereof.

[0133] Embodiment 20. The battery according to any one of Embodiments 9 to 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 (Li-BETI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium trifluoromethanesulfonate (LiTriflate), lithium hexafluoroarsenate (LiAsF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium hexafluorophosphate (LiPF6), lithium nitrate (LiNO3), LiN(SO2CF3)2, LiN(SO2F)2, LiCF3SO3, LiClO4, lithium difluoro(oxalato)borate anion salt (LiDFOB), LiI, LiBr, LiCl, LiOH, LiSO4, LiFSI, LiTFSI, or any combination thereof.

[0134] Embodiment 21. The battery according to any one of the foregoing embodiments, wherein the battery has a capacity retention rate of 80% after 100 or more cycles.

[0135] Embodiment 22. The battery according to any one of the foregoing embodiments, wherein the battery has a capacity retention rate of 80% after 120 or more cycles.

[0136] Embodiment 23. The battery according to Embodiment 21 or Embodiment 22, wherein the battery has a capacity of about 180 mAh / g or higher.

[0137] Embodiment 24. The battery according to Embodiment 21 or Embodiment 22, wherein the battery has a capacity of about 200 mAh / g or higher.

[0138] Embodiment 25. The battery according to any one of the foregoing embodiments, wherein the diluent includes fluorinated ether.

[0139] Embodiment 26. The battery as described in Embodiment 25, wherein the fluorinated ether comprises one or more of the following: 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 having a mixture of n - butyl isomers and isobutyl 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 bis(2,2,2 - trifluoroethyl) carbonate.

[0140] Embodiment 27. The battery as described in any one of Embodiments 9 to 26, wherein the solvating solvent comprises dialkoxyalkanes, dialkyl glycol ethers, disubstituted esters, disubstituted carbonates, trisubstituted phosphates, disubstituted sulfones, tetrasubstituted silanes, or any combination thereof.

[0141] Embodiment 28. The battery as described in any one of the foregoing embodiments, further comprising a separator comprising non - woven fibers, a microporous membrane, a ceramic, or any combination thereof.

[0142] Embodiment 29. A method of forming an electrolyte, comprising:

[0143] a. Dissolving a lithium salt composed of a first lithium salt and a second lithium salt in a solvating solvent to form a solvating solvent - lithium salt solution,

[0144] b. Dissolving a diluent in the solvating solvent - lithium salt solution, and

[0145] c. Further dissolve more of the first lithium salt or the second lithium salt to a concentration exceeding the amount of the lithium salt that can be dissolved in the solvating solvent to form the electrolyte.

[0146] Embodiment 30. The method according to Embodiment 29, wherein the first lithium salt and / or the second lithium salt present in the electrolyte is less than the saturation point of the lithium salt in the electrolyte.

[0147] Embodiment 31. The method according to Embodiment 29 or Embodiment 30, wherein the first lithium salt and / or the second lithium salt has different saturation points in the solvating solvent-lithium solution and the electrolyte.

[0148] Embodiment 32. An electrolyte composed of a solvating solvent, a diluent, and a lithium salt, the lithium salt being composed of a first lithium salt and a second lithium salt, the electrolyte being a solution having a saturation point, the solvating solvent having a saturation point, and the solubility of the lithium salt being at least 5 times the solubility in the solvating solvent, wherein in the absence of the diluent, the first lithium salt and the second lithium salt are present in an amount less than the saturation point of the electrolyte and greater than the saturation point of the solvating solvent.

[0149] Embodiment 33. The electrolyte according to Embodiment 32, wherein the first lithium salt and / or the second lithium salt has different saturation points in the electrolyte and the solvating solvent.

[0150] Examples

[0151] The following examples are for illustrative purposes and do not unduly limit the scope of the present disclosure.

[0152] Example 1

[0153] For Example 1, the battery cells were formed 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-pyrrolidone (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, graphite 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 film. A local high-salt concentration electrolyte was prepared in a 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 molar ratio of 1 / 1.6 / 2 and added to the battery cell. Then the battery cell was sealed and initially cycled at 30 °C with a 0.05C discharge until the upper cut-off voltage of 4.55V, then the voltage was held constant until the current decreased to 0.02C, and then discharged at a constant current of 0.05C to 1.5V. The second cycle was changed to a 0.1C charge and discharge to complete the formation cycle. In the third cycle, a full discharge was performed using a 0.1C discharge and a rate performance evaluation was performed using a 1C charge. Thereafter, the battery cells were cycled to perform a 0.33C / 0.33 cycle performance evaluation.

[0154] Figure 1A Shows the discharge capacities of various solvating solvents used with a disordered rock-salt cathode. Figure 1B Shows the capacity retention rates of various solvating solvents used with a disordered rock-salt cathode.

[0155] Table 1

[0156]

[0157] Table 1 shows the discharge capacities and capacity retention rates of different solvating solvents and diluents from Figures 1A to 1B the figures. Both 1,2-dimethoxyethane (DME) and dimethyl carbonate (DMC) were evaluated as solvating solvents, as Figures 1A to 1BAs shown, a conventional electrolyte (i.e., reference) with a low concentration of LiPF6 salt and an additive package of tris(trimethylsilyl) phosphate + LiDFOB reaches 80% of the initial discharge capacity at 91 cycles. The performance of a locally high-concentration electrolyte with DME (A3: LiFSI / DME / TTE = 1 / 1.2 / 3 (by mole)) used with a DR cathode and a graphite anode is inferior to that of DMC. A locally high-concentration electrolyte with DMC as the solvating solvent shows the desired results when used with a disordered rock salt cathode and a graphite anode. When using TTE (A2) as the diluting solvent in combination with DMC, it shows better performance than BTFE (A1), reaching 80% of the initial discharge capacity only after 149 cycles.

[0158] Example 2

[0159] For Example 2, the battery was set up in the same way as in Example 1, except that the salt was changed.

[0160] Figures 2A to 2B Shows the discharge capacity and capacity retention rate of a lithium salt electrolyte compared to a dilithium salt electrolyte.

[0161] Table 2

[0162]

[0163] Table 2 shows Figures 2A to 2B the results. Using the DMC / TTE solvating solvent / diluting solvent combination, the combination of salts was evaluated in a locally high-concentration electrolyte in combination with a DR cathode and graphite. The formulation containing LiBF4 and LiFSI (A4) showed the best performance.

[0164] Example 3

[0165] For Example 3, the battery and electrolyte were set up the same as in Example 1, except that different formulations of the electrolyte were used.

[0166] Figures 3A to 3B Shows the discharge capacity and capacity retention rate of various diluents used with a disordered rock salt cathode.

[0167] Table 3

[0168]

[0169] The diluents of the locally high-concentration electrolyte include HFPME, TFEEE, OFPTFEE, TFEE, HFPTEE, BTFE, and TTE. The results are highlighted in Table 3.

[0170] As can be seen from Table 3, the TFEE, TTE, and BTFE of the locally high-concentration electrolyte are similar to or have better performance than Figures 1A to 1B (reference) conventional electrolytes.

Claims

1. A battery, comprising: a cathode comprising a disordered rock salt structure; and an electrolyte comprising: a solvating solvent; a lithium salt capable of dissolving in the solvating solvent; and a diluent capable of being miscible with the solvating solvent, wherein the solubility of the lithium salt in the solvating solvent is at least 5 times the solubility in the diluent, and the solvating solvent and the diluent are present in the battery at a diluent / solvating solvent molar ratio of 0.1 to less than 3.

0.

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

3. The battery according to claim 1, wherein the diluent and the solvating solvent are immiscible when the diluent / solvating solvent molar ratio is 5 or greater.

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

0.

5. The battery according to claim 1, wherein the lithium salt is present at a molar ratio of 1:2 or greater with the combination of the solvating solvent and the diluent.

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

7. The battery according to claim 1, wherein the solvating solvent comprises one or more of the following: dialkoxyalkanes, dialkyl glycol ethers, disubstituted esters, disubstituted carbonates, trisubstituted phosphates, disubstituted sulfones, and tetrasubstituted silanes.

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

9. The battery according to claim 1, further comprising an anode comprising one or more of the following: graphite, lithium, lithium alloy, silicon, and silicon alloy.

10. The battery according to claim 1, wherein the battery has a capacity retention rate of 80% after 100 or more cycles.

11. The battery according to claim 10, wherein the battery has a capacity retention rate of 80% after 120 or more cycles.

12. The battery according to claim 10, wherein the battery has a capacity of about 180 mAh / g or higher.

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

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

15. The battery according to claim 14, wherein the fluorinated ether comprises one or more of the following: 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 having a mixture of n-butyl isomers and isobutyl 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 bis(2,2,2-trifluoroethyl) carbonate.

16. The battery according to claim 1, further comprising a separator comprising non-woven fibers, a microporous membrane, ceramics, or any combination thereof.

17. A battery comprising: a cathode; and an electrolyte comprising: a solvating solvent; a lithium salt composed of a first lithium salt and a second lithium salt capable of dissolving in the solvating solvent, the second lithium salt being present at a concentration less than or equal to the concentration of the first lithium salt; and a diluent miscible in the solvating solvent, wherein the solubility of the lithium salt in the solvating solvent is at least 5 times the solubility in the diluent, and the solvating solvent and the diluent are present in the battery at a diluent ratio / solvating solvent ratio of 0.1 to less than 3.

0.

18. The battery according to claim 17, wherein the first lithium salt and the second lithium salt are present in the solvating solvent or a combination of solvating solvent / diluent at a molar ratio of 1 or greater and equal to or less than the saturation point.

19. The battery according to claim 18, wherein the first lithium salt and the second lithium salt are present in the solvating solvent or the combination of solvating solvent / diluent at a molar ratio of 2 or greater up to the saturation point.

20. The battery according to claim 17, wherein the solvating solvent and the diluent are immiscible when the molar ratio of diluent / solvating solvent is 5.0 or greater.

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

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

23. The battery according to claim 17, wherein the cathode is capable of being charged to a voltage of 4.45 or higher.

24. The battery according to claim 17, wherein the cathode comprises a disordered rock salt.

25. The battery according to claim 17, wherein the first lithium salt and the second lithium salt are present in a molar ratio of about 1:2.5 to about 1:5 relative to the combination of the solvating solvent and the diluent.

26. The battery according to 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 battery according to claim 17, wherein the first lithium salt comprises lithium bis(oxalato)borate (LiBOB), lithium bis(pentafluoroethylsulfonyl)imide (Li-BETI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium trifluoromethanesulfonate (LiTriflate), lithium hexafluoroarsenate (LiAsF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium hexafluorophosphate (LiPF6), lithium nitrate (LiNO3), LiN(SO2CF3)2, LiN(SO2F)2, LiCF3SO3, LiClO4, lithium difluoro(oxalato)borate anion salt (LiDFOB), LiI, LiBr, LiCl, LiOH, and LiSO4, or any combination thereof.

28. The battery according to claim 27, wherein the second lithium salt is a lithium salt different from the first lithium salt and comprises lithium bis(oxalato)borate (LiBOB), lithium bis(pentafluoroethylsulfonyl)imide (Li-BETI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium trifluoromethanesulfonate (LiTriflate), lithium hexafluoroarsenate (LiAsF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium hexafluorophosphate (LiPF6), lithium nitrate (LiNO3), LiN(SO2CF3)2, LiN(SO2F)2, LiCF3SO3, LiClO4, lithium difluoro(oxalato)borate anion salt (LiDFOB), LiI, LiBr, LiCl, LiOH, LiSO4, LiFSI, LiTFSI, or any combination thereof.

29. The battery according to claim 17, wherein the battery has a capacity retention rate of 80% after 100 or more cycles.

30. The battery according to claim 29, wherein the battery has a capacity retention rate of 80% at 120 or more cycles.

31. The battery according to claim 29, wherein the battery has a capacity of about 180 mAh / g or higher.

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

33. The battery according to claim 17, wherein the diluent comprises a fluorinated ether.

34. The battery according to claim 33, wherein the fluorinated ether comprises one or more of the following: 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 having a mixture of n - butyl isomers and isobutyl 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 bis(2,2,2 - trifluoroethyl) carbonate.

35. The battery according to 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, a tetrasubstituted silane, or any combination thereof.

36. The battery according to claim 17, further comprising a separator comprising non - woven fibers, a microporous membrane, a ceramic, or any combination thereof.

37. A method of forming an electrolyte, comprising: a. dissolving a lithium salt comprising a first lithium salt and a second lithium salt in a solvating solvent to form a solvating solvent - lithium salt solution, b. dissolving a diluent in the solvating solvent - lithium salt solution, and c. further dissolving more of the first lithium salt or the second lithium salt to a concentration exceeding the amount of the lithium salt that can be dissolved in the solvating solvent to form the electrolyte.

38. The method according to claim 37, wherein the lithium salt is present in the electrolyte at less than the saturation point of the lithium salt in the electrolyte.

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

40. An electrolyte comprising a solvating solvent, a diluent, and a lithium salt, the lithium salt comprising a first lithium salt and a second lithium salt, the electrolyte being a solution having a saturation point, the solvating solvent having a saturation point, and the solubility of the lithium salt in the solvating solvent being at least 5 times the solubility in the diluent, wherein the first lithium salt and the second lithium salt are present in an amount less than the saturation point of the electrolyte and greater than the saturation point of the solvating solvent.

41. The electrolyte according to claim 40, wherein the first lithium salt and the second lithium salt each have different saturation points in the electrolyte and the solvating solvent.

Images