Modified DOPO-based battery electrolytes

Abstract

An electrolyte containing a DOPO-based molecule, an aprotic organic solvent, and a metal salt, and an electrochemical energy storage device containing the electrolyte are disclosed. Herein, derivatives of the 9,10-dihydro-9-oxa-10-organylphosphaphenanthrene-10-oxide (DOPO) molecule are reported as additives for Li-ion batteries. These molecules as electrolyte additives enable stabilization of the cathode and holistic electrolyte system. Cells containing functionalized cyclic ethers in the electrolyte enable safe, high-energy lithium-ion batteries with long cycle life.

Description

[Technical Field]

[0001] cross reference This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 63 / 392,029, filed July 25, 2022, which is incorporated herein by reference in its entirety.

[0002] Field The present disclosure is directed to phosphorus-based 9,10-dihydro-9-oxa-10-organylphosphaphenanthrene-10-oxide derivatives (DOPO) as electrolyte additives, and electrolytes for electrochemical cells containing DOPO molecules. [Background technology]

[0003] background Li-ion batteries are widely used in consumer electronics, electric vehicles (EVs), and energy storage systems (ESSs) and smart grids. In recent years, Li-ion batteries with voltages above 4.35 V have become increasingly important due to the benefits of higher capacity and subsequent energy density. However, the stability of cathode materials at these potentials decreases due to increased oxidation. This can result in electrochemical oxidation of the material and gas generation, which can adversely affect battery performance. Cathode active materials capable of lithium ion insertion / extraction can dissolve in non-aqueous electrolytes, resulting in structural decomposition of the material and increased interfacial resistance. These Li-ion batteries are also typically exposed to extreme temperatures during their operation. The SEI (solid-electrolyte interface) layer formed on the anode gradually decomposes at high temperatures, thus leading to more irreversible reactions and capacity loss. Similarly, the CEI (cathode-electrolyte interface) also loses stability at high temperatures. These reactions occur at the positive and negative electrodes during cycling and are generally more intense at higher temperatures due to faster kinetics. Next-generation Li-ion batteries for use in consumer electronics, EVs, and ESSs will require significant improvements in electrolyte composition compared to current state-of-the-art Li-ion batteries.

[0004] The primary function of an electrolyte is the shuttling of cations and anions between battery electrodes. Until now, researchers have focused on developing battery electrodes, limiting electrolyte development. Traditional Li-ion batteries use carbonate-based electrolytes with a large electrochemical window through which lithium ions can be transported. These electrolytes require functional additives to passivate the anode and form a stable SEI, as well as additives to stabilize the cathode. At the same time, there is a need to design and develop compounds that enable stable and safe cycling of high-voltage, high-energy Li-ion batteries.

[0005] As the industry moves toward higher energy cathode materials for higher energy batteries, stable, efficient, and safe cycling of the battery over a wide voltage window is essential. Li-ion battery electrolytes can be tailored by the addition of various co-solvents and additives based on their application. This tunability has enabled the development of various additives for high voltage stability and safety of Li-ion cells. To sustain this development, battery electrolytes require functional additives that enhance the voltage stability of liquid electrolytes. U.S. Patent No. 8,993,158 to Mitsui reports the use of silyl-containing phosphate derivatives in Li-ion electrolytes. U.S. Patent Nos. 7,494,746 and 8,945,776 to Samsung SDI report the use of silyl-containing phosphite and borate derivatives as additives in Li-ion battery electrolytes. U.S. Patent No. 10,497,975 B2 and U.S. Patent Applications Nos. 20180076483 A1 and 20190089000 A1 to Shenzhen Capchem demonstrate the use of propargyl phosphate esters in Li-ion battery electrolytes. U.S. Patent No. 4,198,492 to Asahi-Dow teaches the use of DOPO-based molecules as flame retardants. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent No. 8,993,158 [Patent Document 2] U.S. Patent No. 7,494,746 [Patent Document 3] U.S. Patent No. 8,945,776 [Patent Document 4] U.S. Patent No. 10,497,975 [Patent Document 5] U.S. Patent Application No. 20180076483 [Patent Document 6] U.S. Patent Application No. 20190089000 [Patent Document 7] U.S. Patent No. 4,198,492 Summary of the Invention

[0007] overview Herein, derivatives of the 9,10-dihydro-9-oxa-10-organylphosphaphenanthrene-10-oxide (DOPO) molecule are reported as additives for Li-ion batteries. As electrolyte additives, these molecules enable stabilization of the cathode and holistic electrolyte system. Cells containing functionalized cyclic ethers in the electrolyte enable safe, high-energy lithium-ion batteries with long cycle life.

[0008] According to one aspect of the present disclosure, a new class of compounds and electrolytes for electrochemical energy storage devices are provided, the electrolytes comprising a DOPO-based molecule, an aprotic organic solvent, and a metal salt.

[0009] According to another aspect of the present disclosure, there is provided an electrolyte for an electrochemical energy storage device, the electrolyte comprising: a DOPO-based molecule; an aprotic organic solvent; a metal salt; and at least one additive.

[0010] According to another aspect of the present disclosure, there is provided an electrochemical energy storage device comprising: a cathode; an anode; a separator; and an electrolyte comprising a DOPO-based molecule, an aprotic organic solvent, and a metal salt.

[0011] According to another aspect of the present disclosure, there is provided an electrolyte for an electrochemical energy storage device, the electrolyte comprising: a DOPO-based molecule; an aprotic organic solvent; a metal salt; and at least one additive, wherein the aprotic organic solvent comprises an open-chain or cyclic carbonate, carboxylic acid ester, nitrite, ether, sulfone, sulfoxide, ketone, lactone, dioxolane, glyme, crown ether, siloxane, phosphate ester, phosphite, monophosphazene, or polyphosphazene, or a mixture thereof.

[0012] According to another aspect of the present disclosure, an electrolyte for an electrochemical energy storage device is provided, the electrolyte comprising: a DOPO-based molecule; an aprotic organic solvent; a metal salt; and at least one additive, wherein the cation of the metal salt is aluminum, magnesium, or an alkali metal, such as lithium or sodium.

[0013] According to another aspect of the present disclosure, there is provided an electrolyte for an electrochemical energy storage device, the electrolyte comprising: a DOPO-based molecule; an aprotic organic solvent; a metal salt; and at least one additive, wherein the additive comprises a compound containing at least one unsaturated carbon-carbon bond, a carboxylic acid anhydride, a sulfur-containing compound, a phosphorus-containing compound, a boron-containing compound, a silicon-containing compound, or a mixture thereof.

[0014] These and other aspects of the present disclosure will become evident upon review of the following detailed description and claims appended hereto. [Brief explanation of the drawings]

[0015] [Figure 1]Figure 1 shows the dQ / dV profiles of the electrolytes tested in the NMC622 / Gr cell.

[0016] [Figure 2] Figure 2 shows the room temperature cycle life characteristics of the electrolytes tested in the NMC622 / Gr cell.

[0017] [Figure 3] Figure 3 shows the dQ / dV profiles of the electrolytes tested in the NMC811 / Gr cell. DETAILED DESCRIPTION OF THE INVENTION

[0018] Detailed Description The technology of the present disclosure generally relates to lithium-ion (Li-ion) battery electrolytes. In particular, the present disclosure is directed to DOPO-based molecules having silyl-based groups or unsaturated end groups; electrolytes containing these compounds; and electrochemical energy storage devices containing these electrolytes. The abbreviation DOPO is defined to refer to derivatives of 9,10-dihydro-9-oxa-10-organylphosphaphenanthrene-10-oxide. Silyl-based functional groups, unsaturated end groups, and organic cationic moieties can be covalently attached to DOPO to generate novel DOPO-based molecules, and therefore, there is a need to create DOPO-based molecules to improve the performance of Li-ion batteries.

[0019] Disclosed herein are DOPO-based molecules bearing silyl-based groups, unsaturated end groups, or organic cationic moieties for use in electrolytes for next-generation Li-ion batteries. While 9,10-dihydro-9-oxa-10-organylphosphaphenanthrene-10-oxide (DOPO) derivatives have been used for their flame-retardant properties, various functional groups can be added to the core DOPO structure to design molecules with different properties. DOPO-derived compounds bearing silyl-based groups and unsaturated end groups according to the present disclosure have high solubility in organic solvents and can be used in electrolytes. Organic cationic moieties can also be covalently attached to the DOPO structure to form fully ionic compounds.

[0020] By adding silyl moieties to Li-ion battery electrolytes, more stable silicon-containing films or layers can be more easily formed on electrode materials, and in some cases, such groups can also act as HO scavengers. Unsaturated end groups, such as allyl, propargyl, and vinyl groups, can also induce polymerization on the electrode surface, thereby increasing resistance. This results in the formation of a film or network on the electrode surface, thus improving long-term performance. The film prevents electrolyte-electrode reactions, resulting in reduced gas evolution during high-temperature storage and cycling. Incorporating organic cationic moieties ionically bonded to the anion onto the DOPO structure creates salts that are essentially nonflammable and have improved solubility in conventional solvents.

[0021] In some embodiments, an electrochemical energy storage device electrolyte includes: a) an aprotic organic solvent system; b) a metal salt; c) a DOPO-based molecule having a silyl-based group, an unsaturated end group, or an organic cationic moiety; and d) at least one additive.

[0022] In certain embodiments of the present disclosure, the molecular structure of a DOPO-based organic compound according to Formula I is shown below: [ka] (In the formula, R1 to R8 are each independently a halogen, C1 to C 12 Substituted and unsubstituted alkyl and fluoroalkyl groups, or C6-C 14 may be an aryl group, wherein hydrogen atoms may be replaced by halogen, alkyl, alkoxy, perfluorinated alkyl, silyl, siloxy, silane, sulfoxide, sulfonyl, amido, azo, ether, thioether groups or combinations thereof; L is (a) a linker comprising a C1-C8 alkyl, alkenyl, alkynyl, alkoxy, ester, carbonyl, phenyl, thioether, sulfoxide, sulfonyl, azo, or aryl group, any of the carbon atoms therein optionally further substituted with a halide or a hydrogen atom replaced by a halide; (b) O or S; or (c) O or S bonded to the linker; R is C1~C 12 Substituted or unsubstituted alkyl or fluoroalkyl groups, or C6-C 14 an aryl group, wherein hydrogen atoms may be replaced by halogen, alkyl, alkoxy, perfluorinated alkyl, silyl, siloxy, silane, sulfoxide, sulfonyl, amido, azo, ether, thioether groups, or combinations thereof; or R is a C1-C cyclic alkyl group terminated with an unsaturated group. 12 Substituted or unsubstituted alkyl or fluoroalkyl groups, or C6-C 14 an aryl group, wherein hydrogen atoms may be replaced with halogen, alkyl, alkoxy, perfluorinated alkyl, silyl, siloxy, silane, sulfoxide, sulfonyl, amido, azo, ether, thioether groups, or combinations thereof; or R is a silane, wherein hydrogen atoms may be replaced with halogen, alkyl, alkoxy, perfluorinated alkyl, silyl, siloxy, silane, sulfoxide, sulfonyl, amido, azo, ether, thioether groups, or combinations thereof; or R is an organic cation ionically bonded to an anion, the cation being either a sulfonium, phosphonium, or a 5- or 6-membered cationic heterocyclic ring having 1 to 3 heteroatoms containing nitrogen, oxygen, silicon, or sulfur as ring members, and the anion being either a halide, nitrate, phosphate, imide, borate, aluminate, arsenide, cyanide, thiocyanate, nitrite, benzoate, carbonate, chlorate, chlorite, chromate, sulfate, sulfite, silicate, thiosulfate, chalcogenide, pnictogenide, oxalate, acetate, formate, or hydroxide).

[0023] In some embodiments, the unsaturated end groups may be selected from the group consisting of alkenyl and alkynyl groups, such as allyl, propargyl, vinyl, and styrene groups.

[0024] In another embodiment, the DOPO-based molecule is present in the electrolyte in the range of 0.01% to 10% by weight.

[0025] The present disclosure also includes methods for synthesizing DOPO-based molecules with silyl-based or unsaturated end groups and the use of such molecules in lithium-ion battery electrolytes, which improve the cycle life and storage characteristics of Li-ion cells operated and stored at high voltages and temperatures.

[0026] According to one aspect of the present disclosure, the electrolyte comprises a metal salt in the range of 10% to 30% by weight. In some embodiments, the cation of the metal salt contains lithium, sodium, aluminum, or magnesium. For example, Li(AsF6); Li(PF6); Li(CF3CO2); Li(C2F5CO2); Li(CF3SO3); Li[N(CP3SO2)2]; Li[C(CF3SO2)3]; Li[N(SO2C2F5)2]; Li(ClO4); Li(BF4); Li(PO2F2); Li[PF2(C2O4)2]; Li[PF4C2O4]; lithium alkyl fluorophosphate; Li[B(C2O4)2]; Li[BF2C2O4]; Li2[B12 Z 12-j H j ];Li2[B 10 X 10-j’ H j’ or mixtures of any two or more of these, where Z is independently in each occurrence a halogen, j is an integer from 0 to 12, and j' is an integer from 1 to 10.

[0027] In some embodiments of the present disclosure, the electrolyte comprises an aprotic organic solvent. The solvent may be present in the range of 60% to 90% by weight of the electrolyte. The solvent may be selected from open-chain or cyclic carbonates, carboxylic acid esters, nitrites, ethers, sulfones, sulfoxides, ketones, lactones, dioxolanes, glymes, crown ethers, siloxanes, phosphate esters, phosphites, monophosphazenes, or polyphosphazenes, or mixtures thereof.

[0028] Examples of aprotic solvents for producing electrolytes include dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dipropyl carbonate, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, bis(trifluoroethyl)carbonate, bis(pentafluoropropyl)carbonate, trifluoroethyl methyl carbonate, pentafluoroethyl methyl carbonate, heptafluoropropyl methyl carbonate, perfluorobutyl methyl carbonate, trifluoroethyl ethyl carbonate, pentafluoroethyl ethyl carbonate, heptafluoropropyl ethyl carbonate, and perfluorobutyl ethyl carbonate. Examples include, but are not limited to, fluorinated oligomers, methyl propionate, ethyl propionate, butyl propionate, dimethoxyethane, triglyme, dimethylvinylene carbonate, tetraethylene glycol, dimethyl ether, polyethylene glycol, triphenyl phosphate, tributyl phosphate, hexafluorocyclotriphosphazene, 2-ethoxy-2,4,4,6,6-pentafluoro-1,3,5,2-5,4-5,6-5 triazatriphosphinine, triphenyl phosphite, sulfolane, dimethyl sulfoxide, ethyl methyl sulfone, ethyl vinyl sulfone, allyl methyl sulfone, divinyl sulfone, fluorophenyl methyl sulfone, and gamma-butyrolactone.

[0029] In some embodiments of the present disclosure, the electrolyte further comprises at least one additive for protecting the electrodes and the electrolyte from decomposition. Thus, the electrolyte of the present technology may comprise an additive that is reduced or polymerized on the surface of the electrode to form a passivation film on the surface of the electrode.

[0030] In some embodiments, the at least one additive is a substituted or unsubstituted linear, branched, or cyclic hydrocarbon containing at least one oxygen atom and at least one aryl, alkenyl, or alkynyl group. The passivation film formed from such an additive can also be formed from a substituted aryl compound or a substituted or unsubstituted heteroaryl compound when the additive contains at least one oxygen atom.

[0031] Representative additives include glyoxal bis(diallyl acetal), tetra(ethylene glycol) divinyl ether, 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane, 2,4,6-triallyloxy-1,3,5-triazine, 1,3,5-triacryloylhexahydro-1,3,5-triazine, 1,2-divinyl furoate, 1 ,3-Butadiene carbonate, 1-vinylazetidin-2-one, 1-vinylaziridin-2-one, 1-vinylpiperidin-2-one, 1-vinylpyrrolidin-2-one, 2,4-divinyl-1,3-dioxane, 2-amino-3-vinylcyclohexanone, 2-amino-3-vinylcyclopropanone, 2-amino-4-vinylcyclobutanone, 2-amino-5-vinylcyclopentanone, 2-aryloxy-cyclopropanone, 2-vinyl-[1,2]oxazetidine, 2-vinyl Aminocyclohexanol, 2-vinylaminocyclopropanone, 2-vinyloxetane, 2-vinyloxy-cyclopropanone, 3-(N-vinylamino)cyclohexanone, 3,5-divinylfuroate, 3-vinylazetidin-2-one, 3-vinylaziridin-2-one, 3-vinylcyclobutanone, 3-vinylcyclopentanone, 3-vinyloxaziridine, 3-vinyloxetane, 3-vinylpyrrolidin-2-one, 2-vinyl-1,3-dioxolane, acrolein diethylene Chill acetal, acrolein dimethyl acetal, 4,4-divinyl-3-dioxolan-2-one, 4-vinyltetrahydropyran, 5-vinylpiperidin-3-one, allyl glycidyl ether, butadiene monoxide, butyl vinyl ether, dihydropyran-3-one, divinyl butyl carbonate, divinyl carbonate, divinyl crotonate, divinyl ether, divinyl ethylene carbonate, divinyl ethylene silicate, 1,3 propane sultone, 1,3-propene sultone, divinyl ethylene sulfate, divinyl ethylene sulfite, divinyl methoxypyrazine, divinyl methyl phosphate, divinyl propylene carbonate, ethyl phosphate, methoxy-o-terphenyl, methyl phosphate, oxetan-2-yl-vinylamine, oxiranyl vinylamine, vinyl carbonate, vinyl crotonate, vinyl cyclopentanone, vinyl ethyl 2-furoate, vinyl ethylene carbonate, 4-fluoro-1,3-dioxolan-2-one, vinyl ethylene silicate, vinyl ethylene sulfate, vinyl ethylene sulfite, vinyl methacrylate, vinyl phosphate, vinyl 2-furoate, vinyl cyclopropanone (vinyl, Cylo propanone), vinyl ethylene oxide, β-vinyl-γ-butyrolactone, or a mixture of any two or more of these. In some embodiments, the additive can be a cyclotriphosphazene substituted with F, alkyloxy, alkenyloxy, aryloxy, methoxy, allyloxy groups, or a combination thereof. For example, the additive can be a (divinyl)-(methoxy)(trifluoro)cyclotriphosphazene, (trivinyl)(difluoro)(methoxy)cyclotriphosphazene, (vinyl)(methoxy)(tetrafluoro)cyclotriphosphazene, (aryloxy)(tetrafluoro)(methoxy)cyclotriphosphazene, or (diaryloxy)(trifluoro)(methoxy)cyclotriphosphazene compound, or a mixture of two or more such compounds.

[0032] In some embodiments, the additive is a sulfur-containing compound, a phosphorus-containing compound, a boron-containing compound, a silicon-containing compound, a fluorine-containing compound, a nitrogen-containing compound, a compound containing at least one unsaturated carbon-carbon bond, a carboxylic acid anhydride, or a mixture thereof. In some embodiments, the additive is vinyl carbonate, vinyl ethylene carbonate, or a mixture of any two or more such compounds.

[0033] In another aspect of the present disclosure, an electrochemical energy storage device is provided, comprising a cathode, an anode, and an electrolyte comprising a DOPO-based molecule as described herein. In one embodiment, the electrochemical energy storage device is a lithium secondary battery. In some embodiments, the secondary battery is a lithium battery, a lithium-ion battery, a lithium-sulfur battery, a lithium-air battery, a sodium-ion battery, or a magnesium battery. In some embodiments, the electrochemical energy storage device is an electrochemical cell, such as a capacitor. In some embodiments, the capacitor is an asymmetric capacitor or a supercapacitor. In some embodiments, the electrochemical cell is a primary cell. In some embodiments, the primary cell is a lithium / MnO2 battery or a Li / poly(carbon monofluoride) battery. In some embodiments, the electrochemical energy storage device is a solar cell.

[0034] In some embodiments, a secondary battery is provided that includes a positive electrode and a negative electrode separated from one another using a porous separator, and an electrolyte described herein.

[0035] Suitable cathode materials for secondary batteries containing the electrolytes described herein include vanadium oxide, lithium peroxide, sulfur, polysulfides, lithium carbon monofluoride (LiCF x (also known as SiO2), or a mixture of any two or more of these, carbon coated olivine cathodes, e.g., LiFePO4, lithium metal oxides, e.g., LiCoO2, LiNiO2, LiNi x Co y Met z O2, LiMn 0.5 Ni 0.5 O2, LiMn 0.1 Co 0.1 Ni 0.8 O2, LiMn 0.2 Co 0.2 Ni 0.6 O2, LiMn 0.3 Co 0.2 Ni 0.5 O2, LiMn 0.33 Co0.33 Ni 0.33 O2, LiMn2O4, LiFeO2, Li 1+x’ Ni α Mn β Co γ Met' δ O 2-z’ F z’ , or A n’ Examples of suitable olivine cathodes include, but are not limited to, B2(XO4)3, where Met is Al, Mg, Ti, B, Ga, Si, Mn, or Co; Met' is Mg, Zn, Al, Ga, B, Zr, or Ti; A is Li, Ag, Cu, Na, Mn, Fe, Co, Ni, Cu, or Zn; B is Ti, V, Cr, Fe, or Zr; and X is P, S, Si, W, or Mo; and 0≦x≦0.3, 0≦y≦0.5, 0≦z≦0.5, 0≦x'≦0.4, 0≦α≦1, 0≦β≦1, 0≦γ≦1, 0≦δ≦0.4, 0≦z'≦0.4, and 0≦n'≦3. In other embodiments, the olivine cathode is 1+x Fe 1z Met'' y PO 4-m X' n where Met″ is Al, Mg, Ti, B, Ga, Si, Ni, Mn, or Co; X′ is S or F; and 0≦x≦0.3, 0≦y≦0.5, 0≦z≦0.5, 0≦m≦0.5, and 0≦n≦0.5.

[0036] Suitable anodes include, for example, lithium metal, graphite materials, amorphous carbon, carbon nanotubes, and Li4Ti5O 12 , tin alloys, silicon, silicon alloys, intermetallic compounds, or mixtures of any two or more such materials. Suitable graphite materials include natural graphite, artificial graphite, graphitized mesocarbon microbeads (MCMB) and graphite fibers, and any amorphous carbon material. In some embodiments, the anode and cathode electrodes are separated from each other by a porous separator.

[0037] The separator for a lithium battery can be a microporous polymer membrane. Examples of polymers for forming the membrane include polypropylene, polyethylene, nylon, cellulose, nitrocellulose, polysulfone, polyacrylonitrile, polyvinylidene fluoride, polybutene, or copolymers or blends of any two or more such polymers. In some cases, the separator is an electron beam-treated microporous polyolefin separator. The electron treatment can increase the separator's deformation temperature and thus enhance its thermal stability at high temperatures. Additionally or alternatively, the separator can be a shutdown separator. A shutdown separator can have a trigger temperature greater than about 130°C, allowing the electrochemical cell to operate at temperatures up to about 130°C.

[0038] The present disclosure is further illustrated with reference to the following specific examples, it being understood that these examples are offered by way of illustration and are not intended to limit the scope of the disclosure or the claims that follow. [Example]

[0039] Example A Synthesis of 10-mercaptopropyl TEOS-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide [ka] A 250 mL flask equipped with a magnetic stir bar, addition funnel, nitrogen inlet, and thermocouple was charged with 10 g of DOPO in 100 mL of dichloromethane (DCM). The flask was cooled to 10°C in an ice-water bath. To the cold slurry, 6.8 g of N-chlorosuccinimide (NCS) was added in portions, maintaining the temperature below 15°C. The ice-water bath was removed, and the slurry was stirred under nitrogen. As the reaction warmed, an exotherm began to develop. After 30 minutes, the temperature rose to approximately 40°C, and solids began to dissolve into solution. The reaction was stirred for an additional 30 minutes, at which point everything had dissolved and the temperature was approximately 24°C. TLC (50% ethyl acetate / 50% hexanes) showed no starting material and one new major spot. The solution was then cooled to 8°C. To the cold solution was added 11.0 g of mercaptopropyltriethoxysilane and 4.7 g of triethylamine in 30-40 mL of DCM dropwise over 20 minutes, maintaining the temperature below 15°C. TLC showed no starting chloride and one new spot migrating as expected. The reaction was allowed to reach room temperature. The entire reaction was then placed on a silica gel pad and eluted with 85% DCM / 15% ethyl acetate. Concentrated to a white gum. Slurried in 80 mL of a 60% mixture of ethyl acetate / hexanes overnight. Filtered and air-dried. Collected: white solid, 7 g, 33.5% yield. FTIR:1476.28;1303.27;1198.23;907.74;750.95;713.27;602.69;509.76cm-1.

[0040] Example B Synthesis of 10-mercaptopropyl TMOS-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide [ka] A 250 mL flask equipped with a magnetic stir bar, addition funnel, nitrogen inlet, and thermocouple was charged with 10 g of DOPO in 100 mL of DCM. The flask was cooled to 10°C in an ice-water bath. To the cold slurry, 6.8 g of NCS was added in portions, maintaining the temperature below 15°C. The ice bath was removed, and the slurry was stirred under nitrogen. As the reaction warmed, an exotherm began to develop. After 30 minutes, the temperature rose to approximately 40°C, and solids began to dissolve into solution. The reaction was stirred for an additional 30 minutes, at which point everything had dissolved and the temperature was approximately 24°C. TLC (50% ethyl acetate / 50% hexanes) showed no starting material and one new major spot. The solution was then cooled to approximately 8°C. To the cold solution was added 9.1 g of (3-mercaptopropyl)trimethoxysilane and 4.7 g of triethylamine in 30-40 mL of DCM dropwise over 20 minutes, maintaining the temperature below 15°C. TLC showed no starting chloride and one new spot migrating as expected. The reaction was allowed to reach room temperature. The entire reaction was then placed on a silica gel pad and eluted with 85% DCM / 15% ethyl acetate up to 20% ethyl acetate. Concentrated to a white gum. Slurrying overnight in 80 mL of a 60% mixture of ethyl acetate / hexanes gave a white solid. Filtered and air-dried. Collected: 6.1 g, white solid, 51.3% yield. FTIR:1738.41;1302.94;1200.42;946.55, 907.57;750.91;713.02;602.33;509.73cm-1.

[0041] Example C Synthesis of 10-propargyl-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide [ka] A 250 mL flask equipped with a magnetic stir bar, addition funnel, nitrogen inlet, and thermocouple was charged with 10 g of DOPO in 100 mL of DCM. The flask was cooled to 8.8 °C in an ice-water bath. To the cold slurry, 6.8 g of NCS was added portionwise, maintaining the temperature below 15 °C. The ice-water bath was removed, and the slurry was stirred under nitrogen. As the reaction warmed, an exotherm began to develop. After 30 minutes, the temperature rose to approximately 40 °C, and the solids began to dissolve into solution. The reaction was stirred for an additional 30 minutes, at which point everything had dissolved and the temperature was approximately 24 °C. TLC (50% ethyl acetate / 50% hexane) showed no starting material and one new major spot. The solution was then cooled to 8 °C. To the cold solution, 6.6 g of propargyl alcohol and 5.6 g of triethylamine in 20 mL of DCM were added dropwise over 20 minutes, maintaining the temperature below 15 °C. TLC showed no starting chloride and one new spot migrating as expected. The reaction was allowed to come to room temperature. The entire reaction was then placed on a silica gel pad and eluted with 90% DCM / 10% ethyl acetate. Concentrated to a white gum. Slurried in 80 mL of a 50% ethyl acetate / hexane mixture overnight. Filtered and air-dried. Collected: white solid, 6.1 g, 51.3% yield. FTIR:1688.53, 1684.10;1294.21;1192.85;909.61;751.91;638.51;510.17cm-1.

[0042] Further specific examples of suitable DOPO-based molecules according to the present disclosure are listed below. [ka]

[0043] Example D Electrolyte for NMC622 / Gr cells An electrolyte formulation was prepared by combining all electrolyte components in a glass vial in a dry, argon-filled glovebox and stirring for 24 hours to ensure complete dissolution of the salts. DOPO-based molecules with silyl-based groups were added to a base electrolyte formulation containing a 3:7 by weight mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC), with 1 M lithium hexafluorophosphate (LiPF) dissolved therein as the Li+ ion-conducting salt. Conventional additives such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC) were added to the base electrolyte composition. Example 1 (EE1) uses a representative molecule according to the present disclosure. The electrolyte components and additives used are summarized in Table A. [Table A]

[0044] Example E NMC622 / Gr cell electrochemical data The prepared electrolyte formulation was used as the electrolyte in 200 mAh Li-ion pouch cells containing lithium nickel manganese cobalt oxide (NMC622) as the cathode active material and graphite as the anode active material. In each cell, 0.9 mL of electrolyte formulation was added and allowed to soak for 1 hour. The cells were vacuum sealed and subjected to a primary charge at 25 °C for 10 hours before wetting. The cells were then charged to 3.8 V at a C / 25 rate, degassed, and subsequently vacuum sealed. After degassing, the cells were charged and discharged twice between 4.45 and 3.0 V at a C / 10 rate, and the results are summarized in Table B. AC-IR is the internal resistance measured at 1 kHz, and the reported discharge capacity refers to the last cycle of formation at a C / 5 rate. Cells containing all electrolytes had higher AC-IR and lower capacity values compared to CE1, which is a result of the DOPO-based molecules in the electrolyte. The dQ / dV profiles are shown in Figure 1. [Table B]

[0045] As can be seen in Figure 2, the discharge capacities of the cells containing EE1 and EE2 electrolytes are lower than those of the cells containing CE1 and CE2, but the capacity retention after 100 cycles at a 0.5C rate is better. The capacity retention values are summarized in Table C. [Table C]

[0046] Example F Electrolyte for NMC811 / Gr cells A 3:7 mixture by weight of ethylene carbonate (EC) and ethyl methyl carbonate (EMC), and Li + DOPO-based molecules with unsaturated end groups are added to a base electrolyte formulation containing 1 M lithium hexafluorophosphate (LiPF) dissolved therein as the ionically conductive salt. Vinylene carbonate (VC) is used as an additional additive in the comparative example (CE3), while embodiment example (EE3) uses a representative DOPO-based molecule with propargyl groups according to the present disclosure. The electrolyte components and additive weight loadings are summarized in Table D. [Table D]

[0047] Example G NMC811 / Gr cell electrochemical data The prepared electrolyte formulation was used as the electrolyte in 1.8 Ah Li-ion pouch cells containing NMC811 as the cathode active material and graphite as the anode active material. The operating voltage window of the cells was 4.2 to 2.8 V. For each cell, 6 g of electrolyte was added and allowed to soak for 1 hour. The cells were vacuum-sealed and left at room temperature for 24 hours. The cells were then charged to 3.7 V at a C / 25 rate, degassed, and subsequently vacuum-sealed. After degassing, the cells were charged and discharged once between 4.2 and 2.8 V at a C / 10 rate. The results are summarized in Table E. AC-IR is the internal resistance measured at 1 kHz, and the reported discharge capacity is for the last cycle of formation at a C / 5 rate. Figure 3 shows the dQ / dV profile of a cell containing EE3, which contains DOPO-based molecules according to the present disclosure. It can be seen that the VC reaction is suppressed by the addition of DOPO-based molecules. The initial characteristics of the cells containing CE3 and EE3 are comparable. [Table E]

[0048] When tested for high temperature storage, cells containing EE3 exhibited significantly lower thickness gain compared to cells containing CE3, a result of avoiding the electrolyte decomposition reaction that typically occurs at high voltages. EE3 exhibited slightly lower capacity retention than cells containing CE3 due to the additive of Example C. The data are summarized in Table F. [Table F]

[0049] While various embodiments have been shown and described in detail herein, it will be apparent to those skilled in the art that various modifications, additions, substitutions, and the like may be made without departing from the spirit of the disclosure and are therefore considered to be within the scope of the present disclosure as defined in the claims that follow.

Claims

1. a) an aprotic organic solvent; b) a metal salt; c) at least one compound according to formula I, 【Chemistry 6】 During the ceremony, R １ ~R ８ are each independently a halogen, C １ ~C １２ substituted and unsubstituted alkyl and fluoroalkyl groups, or C ６ ~C １４ an aryl group, wherein hydrogen atoms may be replaced by halogen, alkyl, alkoxy, perfluorinated alkyl, silyl, siloxy, silane, sulfoxide, sulfonyl, amido, azo, ether, thioether groups, or combinations thereof; L is (a) C １ ~C ８ a linker comprising an alkyl, alkenyl, alkynyl, alkoxy, ester, carbonyl, phenyl, thioether, sulfoxide, sulfonyl, azo, or aryl group, any of the carbon atoms therein optionally further substituted with a halide or a hydrogen atom replaced by a halide; (b) O or S; or (c) O or S bonded to the linker; R is C １ ~C １２ a substituted or unsubstituted alkyl or fluoroalkyl group, or C ６ ~C １４ an aryl group, wherein hydrogen atoms may be replaced by halogen, alkyl, alkoxy, perfluorinated alkyl, silyl, siloxy, silane, sulfoxide, sulfonyl, amido, azo, ether, thioether groups or combinations thereof; or R is a C terminated with an unsaturated group １ ~C １２ a substituted or unsubstituted alkylfluoroalkyl group, or C ６ ~C １４ an aryl group, wherein hydrogen atoms may be replaced with halogen, alkyl, alkoxy, perfluorinated alkyl, silyl, siloxy, silane, sulfoxide, sulfonyl, amido, azo, ether, thioether groups, or combinations thereof; or R is a silane, wherein hydrogen atoms may be replaced with halogen, alkyl, alkoxy, perfluorinated alkyl, silyl, siloxy, silane, sulfoxide, sulfonyl, amido, azo, ether, thioether groups, or combinations thereof; or R is an organic cation ionically bonded to an anion, wherein the cation is either a sulfonium, phosphonium, or a 5- or 6-membered cationic heterocyclic ring having 1 to 3 heteroatoms, including nitrogen, oxygen, silicon, or sulfur, as ring members, and the anion is either a halide, nitrate, phosphate, imide, borate, aluminate, arsenide, cyanide, thiocyanate, nitrite, benzoate, carbonate, chlorate, chlorite, chromate, sulfate, sulfite, silicate, thiosulfate, chalcogenide, pnictogenide, oxalate, acetate, formate, or hydroxide; Electrolytes.

2. The compound according to formula I has the following structure: 【Chemistry 7】 10. The electrolyte of claim 1, wherein the electrolyte is at least one of:

3. 2. The electrolyte of claim 1, wherein in the compound according to Formula I, R is an organic cation ionically bonded to an anion, the anion is imidazolium, pyrrolidinium, piperidinium, or ammonium.

4. 4. The electrolyte of claim 3, wherein the anion is any of a halide, nitrate, phosphate, imide, borate, aluminate, arsenide, cyanide, thiocyanate, nitrite, benzoate, carbonate, chlorate, chlorite, chromate, sulfate, sulfite, silicate, thiosulfate, chalcogenide, pnictogenide, oxalate, acetate, formate, or hydroxide.

5. 10. The composition of claim 1, wherein the compound according to formula I is present in the electrolyte at a concentration of 0.01% to 10% by weight.

6. 2. The composition of claim 1, wherein the aprotic organic solvent comprises an open-chain or cyclic carbonate, carboxylic acid ester, nitrite, ether, sulfone, ketone, lactone, dioxolane, glyme, crown ether, siloxane, phosphate ester, phosphite, monophosphazene or polyphosphazene, or mixtures thereof.

7. 10. The composition of claim 1, wherein the aprotic organic solvent is present in the electrolyte at a concentration of 60% to 90% by weight.

8. The composition of claim 1 wherein the cation of the metal salt is lithium.

9. 10. The composition of claim 1, wherein the metal salt is present in the electrolyte at a concentration of 10% to 30% by weight.

10. The composition of claim 1 further comprising at least one additive.

11. 11. The composition of claim 10, wherein the at least one additive comprises a sulfur-containing compound, a phosphorus-containing compound, a boron-containing compound, a silicon-containing compound, a fluorine-containing compound, a nitrogen-containing compound, a compound containing at least one unsaturated carbon-carbon bond, a carboxylic acid anhydride, an epoxide, or a mixture thereof.

12. The composition of claim 10, wherein the at least one additive is present in the electrolyte at a concentration of 0.01% to 10% by weight.

13. a. a cathode; b. an anode; c. the electrolyte of claim 1; d. Separator and 1. An electrochemical energy storage device comprising:

14. The cathode is LiFePO ４ , LiCoO ２ , LiNiO ２ , LiNi ｘ Co ｙ Met ｚ O ２ , LiMn ０．５ Ni ０．５ O ２ , LiMn ０．１ Co ０．１ Ni ０．８ O ２ , LiMn ０．２ Co ０．２ Ni ０．６ O ２ , LiMn ０．３ Co ０．２ Ni ０．５ O ２ , LiMn ０．３３ Co ０．３３ Ni ０．３３ O ２ , LiMn ２ O ４ , LiFeO ２ , Li １＋ｘ’ Ni α Mn β Co γ Met' δ O ２－ｚ’ F ｚ’ , or A ｎ’ B ２ (XO ４ ) ３ 14. The device of claim 13, wherein Met is Al, Mg, Ti, B, Ga, Si, Mn, or Co; Met′ is Mg, Zn, Al, Ga, B, Zr, or Ti; A is Li, Ag, Cu, Na, Mn, Fe, Co, Ni, Cu, or Zn; B is Ti, V, Cr, Fe, or Zr; X is P, S, Si, W, or Mo; and 0≦x≦0.3, 0≦y≦0.5, 0≦z≦0.5, 0≦x′≦0.4, 0≦α≦1, 0≦β≦1, 0≦γ≦1, 0≦δ≦0.4, 0≦z′≦0.4, and 0≦h′≦3.

15. The anode may be made of lithium metal, graphite material, amorphous carbon, Li ４ Ti ５ O １２ 14. The device of claim 13, comprising a tin alloy, silicon, a silicon alloy, an intermetallic compound, or a mixture thereof.

16. 14. The device of claim 13, wherein the porous separator comprises an electron beam treated microporous polyolefin separator or a microporous polymer membrane comprising nylon, cellulose, nitrocellulose, polysulfone, polyacrylonitrile, polyvinylidene fluoride, polypropylene, polyethylene, polybutene, or a copolymer or blend of any two or more such polymers.

17. 14. The device of claim 13, wherein the aprotic organic solvent comprises an open-chain or cyclic carbonate, carboxylic acid ester, nitrite, ether, sulfone, ketone, lactone, dioxolane, glyme, crown ether, siloxane, phosphate ester, phosphite, monophosphazene or polyphosphazene, or mixtures thereof.

18. 14. The device of claim 13, wherein the cation of the metal salt is lithium.

19. 14. The device of claim 13, wherein the electrolyte of claim 1 further comprises at least one additive.

20. 20. The device of claim 19, wherein the at least one additive comprises a sulfur-containing compound, a phosphorus-containing compound, a boron-containing compound, a silicon-containing compound, a fluorine-containing compound, a nitrogen-containing compound, a compound containing at least one unsaturated carbon-carbon bond, a carboxylic acid anhydride, an epoxide, or a mixture thereof.

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