Stabilization of alkali metal pf6 salts in carbonate solutions

Abstract

Disclosed herein is a stabilized salt-solvent mixture comprising a salt, a carbonate solvent, and a silicone (OS) compound wherein the OS compound inhibits degradation reactions within the salt-solvent mixture. Also disclosed herein is a method of mitigating degradation of a salt / carbonate solution, the method comprising adding to the salt / carbonate solution an amount of an OS compound that inhibits a degradation reaction within the salt / carbonate solution. Such OS compounds may be added to the carbonate solvent before or after salt dissolution to form a salt-solvent mixture.

Description

Background Art

[0001] Lithium hexafluorophosphate (LiPF6) is the most commonly used lithium salt in lithium-ion battery technology today. While it has many useful properties as a battery ion conductor, the material is quite sensitive to degradation through a number of different mechanisms. These different degradation pathways are accelerated at high temperatures. This degradation is an ongoing problem even before LiPF6 is formulated into an electrolyte and then added to a battery. Before the salt reaches the battery, it must be stored and then go through a multi-step process of electrolyte formulation and production. Throughout the storage and electrolyte production process, the salt is susceptible to degradation, ultimately reducing the performance of the battery to which it is added. Other candidate alkali metal salts include NaPF6, which suffers from these same issues.

[0002] Therefore, there is a long-felt unmet need to mitigate the degradation of electrolyte salts in both simple and complex solvent systems. Summary of the invention

[0003] Disclosed herein is a stabilized salt-in-solvent mixture for use in an electrolyte formulation for a lithium ion charge storage device such as a battery. The mixture comprises a salt as disclosed herein, a carbonate solvent, and an organosilicon (OS) compound, wherein the OS compound inhibits degradation reactions within the salt-solvent mixture. Also disclosed herein is a corresponding method for increasing the storage stability of a composition containing LiPF6 or NaPF6 by inhibiting thermal and chemical degradation in the composition. This is achieved by adding one or more OS compounds as disclosed herein to the composition.

[0004] In certain embodiments, the stabilized salt-solvent mixture comprises an alkali metal salt (eg, LiPF6 or NaPF6), a linear carbonate (eg, ethyl methyl carbonate (EMC)), and an OS compound.

[0005] Also disclosed herein is a method for mitigating degradation of a salt / carbonate solution used in an electrolyte formulation or in the formulated electrolyte itself before and after the electrolyte is added to a lithium-ion battery or other charge storage device. The method includes adding to the salt / carbonate solution an amount of an OS compound that inhibits degradation reactions in the salt / carbonate solution. The OS compound can be added to a carbonate solvent before or after the salt is dissolved to form a salt-solvent mixture.

[0006] The OS compound used herein is selected from the group consisting of:

[0007] (R) 4-a -Si-(Sp-Y) a -Z b(Formula I)

[0008] in:

[0009] "a" is an integer from 1 to 4; "b" is an integer from 0 to (3×a);

[0010] "Z", absent when "b" = 0, is selected from the group consisting of "R" and:

[0011]

[0012] Wherein each "R" is independently selected from the group consisting of halogen, C 1-6 A straight-chain or branched alkyl, alkenyl or alkynyl group and a C 1-6 a straight-chain or branched haloalkyl, haloalkenyl or haloalkynyl group;

[0013] Each "Sp" in Formula I and Formula II is independently selected from C 1-15 Straight or branched chain alkylene and C 1-15 A group consisting of a straight chain or branched chain halogenated alkylene group; and

[0014] Each "Y" in Formula I is independently selected from the group consisting of organic polar groups.

[0015] In certain forms of the compounds, each "Y" is independently an organic polar group selected from the group consisting of:

[0016]

[0017]

[0018] The bent bond represents C 2-6 Alkylene bridging moiety.

[0019] An exemplary OS compound within the scope of the present disclosure is F1S3MN (4-(fluorodimethylsilyl)butyronitrile), which has the following structure:

[0020]

[0021] An exemplary OS compound within the scope of the present disclosure is DF1S2MN (3-(difluorodimethylsilyl)propionitrile), which has the following structure:

[0022]

[0023] Specifically, the following compositions and methods are disclosed and claimed herein:

[0024] 1. A stabilized salt-solvent mixture comprising a salt, a carbonate solvent; and an organosilicon compound, wherein the organosilicon compound inhibits degradation reactions in the salt-solvent mixture.

[0025] 2. The stabilized salt-solvent mixture according to claim 1, wherein the salt is an alkali metal PF6 salt.

[0026] 3. The stabilized salt-solvent mixture according to claim 2, wherein the salt is selected from the group consisting of LiPF6 and NaPF6.

[0027] 4. The stabilized salt-solvent mixture of claim 2, wherein the carbonate is a linear carbonate.

[0028] 5. The stabilized salt-solvent mixture of claim 2, wherein the carbonate is selected from the group consisting of ethyl methyl carbonate, dimethyl carbonate, and diethyl carbonate, ethylene carbonate, propylene carbonate, and gamma-butyrolactone.

[0029] 6. The stabilized salt-solvent mixture according to claim 2, wherein the organosilicon compound is selected from the group consisting of:

[0030] (R) 4-a -Si-(Sp-Y) a -Z b (Formula I)

[0031] in:

[0032] "a" is an integer from 1 to 4; "b" is an integer from 0 to (3×a);

[0033] "Z", absent when "b" = 0, is selected from the group consisting of "R" and:

[0034]

[0035] Wherein each "R" is independently selected from the group consisting of halogen, C 1-6 A straight-chain or branched alkyl, alkenyl or alkynyl group and a C 1-6 a straight-chain or branched haloalkyl, haloalkenyl or haloalkynyl group;

[0036] Each "Sp" in Formula I and Formula II is independently selected from C 1-15 Straight or branched chain alkylene and C 1-15 A group consisting of a straight chain or branched chain halogenated alkylene group; and

[0037] Each "Y" in Formula I is independently selected from the group consisting of organic polar groups.

[0038] 7. The stabilized salt-solvent mixture of claim 6, wherein each "Y" is independently an organic polar group selected from the group consisting of:

[0039]

[0040] The bent bond represents C 2-6 Alkylene bridging moiety.

[0041] 8. The stabilized salt-solvent mixture of claim 7, wherein each "Y" is independently an organic polar group selected from the group consisting of:

[0042]

[0043] 9. The stabilized salt-solvent mixture of claim 2, wherein the organosilicon compound is:

[0044]

[0045] 10. The stabilized salt-solvent mixture of claim 2, wherein the organosilicon compound is:

[0046]

[0047] 11. The stabilized salt-solvent mixture according to any one of claims 1 to 10 for use in an electrolyte formulation.

[0048] 12. A stabilized salt-solvent mixture comprising an alkali metal PF6 salt, a carbonate solvent; and an organosilicon compound selected from the group consisting of:

[0049] (R) 4-a -Si-(Sp-Y) a —Z b (Formula I)

[0050] in:

[0051] "a" is an integer from 1 to 4; "b" is an integer from 0 to (3×a);

[0052] "Z", absent when "b" = 0, is selected from the group consisting of "R" and:

[0053]

[0054] Wherein each "R" is independently selected from the group consisting of halogen, C 1-6 A straight-chain or branched alkyl, alkenyl or alkynyl group and a C 1-6 a straight-chain or branched haloalkyl, haloalkenyl or haloalkynyl group;

[0055] Each "Sp" in Formula I and Formula II is independently selected from C 1-15 Straight or branched alkylene and C 1-15 A group consisting of a linear or branched halogenated alkylene group; and

[0056] Each "Y" in Formula I is independently selected from the group consisting of:

[0057]

[0058]

[0059] The bent bond represents C 2-6 an alkylene bridging moiety;

[0060] The organosilicon compound inhibits the degradation reaction in the salt-solvent mixture.

[0061] 13. The stabilized salt-solvent mixture of claim 12, wherein the carbonate is selected from the group consisting of ethyl methyl carbonate, dimethyl carbonate, and diethyl carbonate, ethylene carbonate, propylene carbonate, and gamma-butyrolactone.

[0062] 14. The stabilized salt-solvent mixture of claim 12, wherein each "Y" is independently an organic polar group selected from the group consisting of:

[0063]

[0064] 15. The stabilized salt-solvent mixture of claim 12, wherein the organosilicon compound is:

[0065]

[0066] 16. The stabilized salt-solvent mixture of claim 12, wherein the organosilicon compound is:

[0067]

[0068] 17. The stabilized salt-solvent mixture of claim 12, wherein the salt is selected from the group consisting of LiPF6 and NaPF6.

[0069] 18. The stabilized salt-solvent mixture according to any one of claims 12 to 17 for use in an electrolyte formulation.

[0070] 19. A method of mitigating degradation of a salt / carbonate solution used in an electrolyte formulation or in a formulated electrolyte, the method comprising adding to the salt / carbonate solution an amount of an organosilicon compound selected from the group consisting of:

[0071] (R) 4-a -Si-(Sp-Y) a -Z b (Formula I)

[0072] in:

[0073] "a" is an integer from 1 to 4; "b" is an integer from 0 to (3×a);

[0074] "Z", absent when "b" = 0, is selected from the group consisting of "R" and:

[0075]

[0076] Wherein each "R" is independently selected from the group consisting of halogen, C 1-6 A straight-chain or branched alkyl, alkenyl or alkynyl group and a C 1-6 a straight-chain or branched haloalkyl, haloalkenyl or haloalkynyl group;

[0077] Each "Sp" in Formula I and Formula II is independently selected from C 1-15 Straight or branched chain alkylene and C 1-15 A group consisting of a straight chain or branched chain halogenated alkylene group; and

[0078] Each "Y" in Formula I is independently selected from the group consisting of:

[0079]

[0080]

[0081] The bent bond represents C 2-6 an alkylene bridging moiety;

[0082] The organosilicon compound inhibits the degradation reaction in the salt-solvent mixture.

[0083] 20. A stabilized salt-solvent mixture comprising an alkali metal PF6 salt, a carbonate solvent; and an organosilicon compound, wherein the concentration of hydrofluoric acid (HF) in the mixture is less than about 100 ppm after storage at 100°C for 20 days.

[0084] 21. The stabilized salt-solvent mixture of claim 20, wherein the hydrofluoric acid (HF) concentration in the mixture is less than about 20 ppm after storage at 100°C for 20 days.

[0085] 22. The stabilized salt-solvent mixture of claim 20, wherein the hydrofluoric acid (HF) concentration in the mixture is less than about 10 ppm after storage at 100°C for 20 days.

[0086] 23. The stabilized salt-solvent mixture of claim 20, wherein the hydrofluoric acid (HF) concentration in the mixture is less than about 5 ppm after storage at 100°C for 20 days.

[0087] 24. The stabilized salt-solvent mixture of claim 20, wherein the organosilicon compound is selected from the group consisting of:

[0088] (R) 4-a -Si—(Sp-Y) a -Z b (Formula I)

[0089] in:

[0090] "a" is an integer from 1 to 4; "b" is an integer from 0 to (3×a);

[0091] "Z", absent when "b" = 0, is selected from the group consisting of "R" and:

[0092]

[0093] Wherein each "R" is independently selected from the group consisting of halogen, C 1-6 A straight-chain or branched alkyl, alkenyl or alkynyl group and a C 1-6 a straight-chain or branched haloalkyl, haloalkenyl or haloalkynyl group;

[0094] Each "Sp" in Formula I and Formula II is independently selected from C 1-15 Straight or branched chain alkylene and C 1-15 A group consisting of a straight chain or branched chain halogenated alkylene group; and

[0095] Each "Y" in Formula I is independently selected from the group consisting of:

[0096]

[0097]

[0098] The bent bond represents C 2-6 an alkylene bridging moiety;

[0099] The organosilicon compound inhibits the degradation reaction in the salt-solvent mixture.

[0100] 25. The stabilized salt-solvent mixture of claim 20, wherein the carbonate is selected from the group consisting of ethyl methyl carbonate, dimethyl carbonate, and diethyl carbonate, ethylene carbonate, propylene carbonate, and gamma-butyrolactone.

[0101] 26. The stabilized salt-solvent mixture of claim 20, wherein the concentration of the organosilicon compound is calculated using the following formula:

[0102]

[0103] Where Vol% OS is the calculated concentration of the organosilicon compound and [ppm H2O] is the measured concentration of water in the salt-solvent mixture. OS is the density of the organosilicon compound, ρ sol is the density of the solvent mixture, MW OS is the molecular weight of the organosilicon compound, MW H2O is the molecular weight of water.

[0104] 27. The stabilized salt-solvent mixture of claim 20, wherein the organosilicon compound is selected from the group consisting of:

[0105] (R) 4-a -Si-(Sp-Y) a -Z b (Formula I)

[0106] in:

[0107] "a" is an integer from 1 to 4; "b" is an integer from 0 to (3×a);

[0108] "Z", absent when "b" = 0, is selected from the group consisting of "R" and:

[0109]

[0110] Wherein each "R" is independently selected from the group consisting of halogen, C 1-6 Straight or branched alkyl, alkenyl or

[0111] Alkynyl and C 1-6 a straight-chain or branched haloalkyl, haloalkenyl or haloalkynyl group;

[0112] Each "Sp" in Formula I and Formula II is independently selected from C 1-15 Straight or branched chain alkylene and C 1-15 A group consisting of a straight or branched chain halogenated alkylene group; and

[0113] Each "Y" in Formula I is independently selected from the group consisting of:

[0114]

[0115]

[0116] The bent bond represents C2-6 an alkylene bridging moiety;

[0117] The organosilicon compound inhibits the degradation reaction in the salt-solvent mixture.

[0118] 28. The stabilized salt-solvent mixture of claim 27, wherein the carbonate is selected from the group consisting of ethyl methyl carbonate, dimethyl carbonate, and diethyl carbonate, ethylene carbonate, propylene carbonate, and gamma-butyrolactone.

[0119] The objects and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0120] Figure 1A Depicted are the autocatalytic HF production in a salt-solvent mixture (top; HF is a marker of degradation) and the reduction of HF production in an organosilicon (OS) nitrile formulation (bottom). A salt-solvent mixture containing ethylene carbonate / diethyl carbonate (EC / DEC) (3 / 7, %v) and 1M LiPF6 at 100°C was used as a control. A series of solutions were prepared with the addition of 100 ppm H2O (+100 ppm) and 500 ppm H2O (+500 ppm) and compared with no H2O addition (+0 ppm). Figure 1A The labels next to the curves indicate the amount of H2O added before thermal storage.

[0121] Figure 1B The decomposition of LiPF6 salt with and without the addition of OS is described. The decomposition of LiPF6 salt increases exponentially without OS. The decomposition of LiPF6 salt does not increase with OS. A salt-solvent mixture containing EC / DEC (3 / 7, %v) and 1M LiPF6 at 100°C was used as a control. A series of solutions were prepared with the addition of 100 ppm H2O (+100 ppm) and 500 ppm H2O (+500 ppm) and compared with no H2O addition (+0 ppm). The labels next to the curves indicate the amount of H2O added before hot storage.

[0122] Figure 1C An exemplary chemical reaction for the removal of HF by OS nitrile is depicted (F1S3MN, top). OS nitrile scavenges H + To form three amides (lower left) and one ether (lower right).

[0123] 1D depicts the reduction of HF (upper graph) and the formation of amides (lower graph) in a salt-solvent mixture containing EC / EMC, 1M LiPF6, and OS nitrile. A series of solutions were prepared by adding 100 ppm H2O (+100 ppm) and 500 ppm H2O (+500 ppm) and compared with no H2O addition (+0 ppm). In the lower graph, the labels next to the curves indicate the amount of H2O added before hot storage.

[0124] Figure 2A Depicted is the OS / PF5 complex with an exemplary OS nitrile (F1S3MN). 19 F NMR spectrum. The composition comprises F1S3MN and 1M LiPF6 and is maintained at 100°C for 260 days.

[0125] Figure 2B Depicted are the OS / PF5 composites with exemplary OS nitrile (F1S3MN) in carbonate blends. 19 FNMR spectrum. The composition comprises EC / F1S3MN (volume ratio of 2 to 8) and 1M LiPF6 and is maintained at 100°C for 260 days.

[0126] Figure 3A Depicted are HF production in a salt-solvent mixture containing EC / EMC and 1 M LiPF6 at 100°C (upper panel) and 70°C (lower panel). HF production is clearly autocatalytic at 100°C, but not at the lower temperature of 70°C.

[0127] Figure 3B Depicted is a salt-solvent mixture containing OS nitrile (F1S3MN; DF1S2MN) stored at 30°C for 141 days. A salt-solvent mixture without addition of OS nitrile was used as a control. A series of solutions were prepared with the addition of 500 ppm H2O (+500 ppm) and compared with no addition of H2O (nominal moisture).

[0128] Figure 3C Depicted is a salt-solvent mixture containing OS nitrile (F1S3MN; DF1S2MN) stored at 45°C for 141 days (upper graph). A salt-solvent mixture without addition of OS nitrile was used as a control. A series of solutions were prepared with the addition of 500 ppm H2O (+500 ppm) and compared with no addition of H2O (nominal moisture). The lower graph shows the reduction in HF from 70 days to 141 days in the control salt-solvent mixture and the salt-solvent mixture containing OS nitrile.

[0129] Figure 4A and Figure 4B The reduction in HF production in salt-solvent mixture formulations containing various OS nitrile molecules is depicted. All OS nitriles were prepared at 0.13 M ( Figure 4A) or 1M( Figure 4B ) concentration was present in a salt-solvent mixture containing ethylene carbonate / diethyl carbonate (EC / DEC) (3 / 7, %v) and 1M LiPF6. No water was added to the salt-solvent mixture before hot storage. For 0.13M OS ( Figure 4A ), the curves of F1S2MN and TF1S2MN overlap, making only the TF1S2MN curve visible.

[0130] Figure 5A Depicted is the reduction in HF production in salt-solvent mixture formulations containing other nitriles (succinonitrile, adiponitrile, and valeronitrile; structures of the compounds are shown on the right) compared to OS, F1S3MN at 100° C. A series of solutions were prepared with the addition of 500 ppm H2O (+500 ppm H2O) and compared with no H2O addition (No H2O).

[0131] Figure 5B Decomposition of other nitriles (succinonitrile, adiponitrile and valeronitrile) compared to OS (F1S3MN) at 100° C. A series of solutions were prepared with the addition of 500 ppm H2O (+500 ppm H2O) and compared to no H2O addition (No H2O).

[0132] Figure 6 Depicted is the reduction in HF production at 100° C. in salt-solvent mixture formulations containing compounds with trifluoro structures, including TF1S2MN, TF-BN (trifluorobutyronitrile), and TF1S6M (non-nitrile). The structures of the compounds are shown at the bottom.

[0133] Fig. 7A Depicted are HF concentrations in salt-solvent mixture formulations containing EC and different concentrations of OS (F1S3MN) at 100° C. (left: 1% OS and 2% OS; right: 5% OS, 8% OS, 16% OS, 20% OS, and 87% OS). The dielectric constant of the EC blend is 89.

[0134] Figure 7B Depicted are HF concentrations in salt-solvent mixture formulations containing EC / DEC (3 / 7) and different concentrations of OS (0%, 2%, 5%, 10%, and 16%) at 100° C. The dielectric constant of the EC / DEC blend is 21.8.

[0135] Figure 7C Depicted is HF production in a salt-solvent mixture formulation containing high salt EMC, 2.5 M LiPF6 at 100°C. HF production with 500 ppm H2O added (+500 ppm H2O) was compared to HF production without H2O addition (nominal moisture).

[0136] Fig.7D Depicted is the reduction in HF production in salt-solvent mixture formulations containing high-salt EMC, 2.5 M LiPF6, and different concentrations of OS at 100°C. A salt-solvent mixture without OS was used as a control. No water was added to the mixture prior to hot storage. DETAILED DESCRIPTION

[0137] The elements and method steps described herein may be used in any combination or order whether explicitly disclosed or not.

[0138] All combinations of method steps used herein can be performed in any order unless otherwise indicated or clearly indicated to the contrary in the context of the referenced combination.

[0139] The systems disclosed herein may include, be composed of, or substantially consist of the various steps and elements disclosed herein. The disclosure provided herein may be appropriately implemented without any element or step not specifically disclosed herein.

[0140] All references to singular features or limitations of the invention shall include the corresponding plural features or limitations and vice versa unless otherwise stated or the context of the reference clearly indicates the contrary. The indefinite articles "a" and "an" mean "one or more".

[0141] The numerical ranges used herein are intended to include each value and subset of values ​​contained within the range, whether specifically disclosed or not. In addition, these numerical ranges should be interpreted as providing support for claims for any value or subset of values ​​within the range. For example, disclosures from 1 to 10 should be interpreted as supporting ranges from 2 to 8, from 3 to 7, from 5 to 6, from 1 to 9, from 3.6 to 4.6, from 3.5 to 9.9, and the like.

[0142] All patents, patent publications, and peer-reviewed publications (i.e., "references") cited herein are expressly incorporated herein by reference, as if each individual reference was specifically and individually indicated to be incorporated herein by reference. In the event of a conflict between the present disclosure and an incorporated reference, the present disclosure controls.

[0143] It is to be understood that the compounds and compositions disclosed herein are not limited to the exact construction and arrangement of parts illustrated and described herein, but include such modified forms thereof as fall within the scope of the claims.

[0144] Degradation mechanism of alkali metal PF6 salts:

[0145] Alkali metal PF6 salts (e.g., LiPF6) are known to have at least two degradation mechanisms when present in carbonate-based solvent systems. The first is through interaction with any amount of water that may be present in the system:

[0146]

[0147] This reaction results in the formation of highly acidic hydrofluoric acid (HF) and insoluble LiF. HF can in turn catalyze further degradation of the carbonate material and cause the production of more HF through further degradation of the carbonate components and the resulting insoluble LiF.

[0148]

[0149] Although great care is taken in the industry to keep water contamination in LiPF6 / carbonate solutions as low as possible, it is difficult and expensive to completely eliminate water contamination.

[0150] In addition, there is a second degradation mechanism for LiPF6 in carbonate systems that does not require any additional external water:

[0151]

[0152] It has been established that in carbonate solutions, LiPF6 is always in equilibrium with the LiF-PF5 pair. At higher temperatures, this equilibrium shifts to the right. The PF5 molecule is a very reactive gas molecule that reacts immediately with the carbonate carrier material, resulting in a carbonate decomposition reaction that also produces HF and is autocatalytic. Due to autocatalysis, the carbonate decomposition reaction, once started, will only accelerate over time.

[0153] Scavenging of H by amines + :

[0154] It must be noted that in PF6 -1 The decomposition of carbonates in the presence of anions leads to the production of HF, and the decomposition of carbonates generally tends to produce acidic species that catalyze further decomposition. + is fundamental to preventing this decomposition. One way that acids can be scavenged is by reaction with amines to form ammonium salts. The reaction between amines and acids is very well known and is an effective method for removing acidic hydrogen from solution by trapping it in a stable salt with an NH bond. Organosilicon amines can be used to remove H present in salt-solvent mixtures or electrolytes by trapping + cations to provide immediate reduction of HF and other acidic compounds.

[0155] Mitigation of degradation of alkali metal PF6 salts by organosilicon compounds:

[0156] Disclosed herein is a stabilized salt-solvent mixture. The mixture comprises a salt, a carbonate solvent and an organosilicon (OS) compound, wherein the OS compound controls, inhibits or slows down degradation reactions in the salt-solvent mixture. The stabilized salt-solvent mixture can be used in electrolyte formulations used in lithium-ion batteries.

[0157] As used herein, salts are purposefully broadly defined to include all salts, including, but not limited to, lithium salts, sodium salts, potassium salts, magnesium salts, borates, phosphates, etc. Non-limiting examples include lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium perchlorate, potassium hexafluorophosphate, potassium tetrafluoroborate, potassium perchlorate, magnesium hexafluorophosphate, magnesium perchlorate, magnesium tetrafluoroborate, tetraethylammonium tetrafluoroborate (TEA-TFB), tetrabutylphosphonium tetrafluoroborate, tetrabutylphosphonium hexafluorophosphate, tetrabutylammonium tetrafluoroborate, tetraethylammonium hexafluorophosphate, and tetraethylammonium perchlorate.

[0158] Carbonate is generally used as a solvent for electrolyte compositions. Non-limiting examples of carbonate solvents include linear carbonates, such as ethyl methyl carbonate (EMC), dimethyl carbonate (DMC) and diethyl carbonate (DEC); cyclic carbonates, such as ethylene carbonate (EC), propylene carbonate (PC) and γ-butyrolactone; and various fluorine-containing linear or cyclic carbonates. Salt-solvent mixtures can include carbonate solvents or carbonate solvent mixtures with a wide concentration range, including but not limited to about 90% by weight to about 100% by weight of the total solvent. Examples of suitable total carbonate solvent concentrations include about 90% by weight, about 95% by weight, about 97% by weight, about 98% by weight, about 99% by weight, about 99.5% by weight, about 99.97% by weight of the total solvent, or between and including the range of any of the foregoing amounts.

[0159] The OS compounds used herein will be described in detail in the next section. The salt-solvent mixture can contain a wide range of OS compounds, including but not limited to about 0.03 wt % to about 10 wt % of the total solvent. Examples of suitable OS compound concentrations include about 0.03 wt %, about 0.5 wt %, about 1 wt %, about 2 wt %, about 3 wt %, about 5 wt %, about 10 wt %, or a range between and including any of the foregoing amounts of the total solvent.

[0160] As disclosed herein, OS molecules have properties that can mitigate both forms of salt degradation described above. The first use case for OS-based nitrile materials can be demonstrated in the presence of free water in the LiPF6 / carbonate system. When water reacts with LiPF6, the OS nitrile molecules act as proton traps, preferentially reacting with the acidic component and removing it, thereby preventing it from providing further autocatalytic decomposition in the form of HF. Figure 1Ashows the reduction in HF observed in the salt-solvent mixture containing OS nitrile compared to the autocatalytic HF formation in the carbonate-based control mixture, and Figure 1B The inhibition of total salt decomposition in the OS nitrile mixture is shown. These are compared to the same systems with water added (+100 ppm, +500 ppm). Figure 1C and Figure 1D The OS nitrile is shown to scavenge hydrogen to convert into a stable amide structure.

[0161] The following table shows the calculated equivalent amount of water that the HF formed above can accommodate if the water is fully converted to HF (1 mol OS to 1 mol HF) by stabilizing the proton capture mechanism of OS. The H2O equivalent ppm based on HF stabilized by OS in carbonate solvent was calculated using the following formula:

[0162]

[0163]

[0164] Table 1: Calculated H2O equivalent ppm based on HF stabilized by OS in carbonate solvents for two exemplary OS compounds in three exemplary linear carbonate solvents.

[0165]

[0166] The above formula can also be used to estimate the required OS concentration for a given amount of water impurity in a salt-solvent mixture.

[0167]

[0168] where ρ OS is the density of the organosilicon compound, ρ sol is the density of the solvent mixture, MW OS is the molecular weight of the organosilicon compound, MW H2O is the molecular weight of water and [ppm H2O] is the measured concentration of water in the salt-solvent mixture.

[0169] Furthermore, experimental work has shown that OS nitrile is able to complex with the PF5 species produced in the equilibrium reaction, again mitigating further decomposition of carbonate solutions via an autocatalytic reaction. Figure 2A and Figure 2B The NMR spectrum of the OS / PF5 complex with an exemplary OS nitrile (F1S3MN) is shown.

[0170] The result of mitigating these two possible degradation pathways is that the LiPF6 / carbonate system is much more stable over time and temperature. This is true whether the system is stored in a simple container or in the form of a fully assembled battery or other charge storage device.

[0171] By preventing the occurrence of the two degradation mechanisms described above, the methods described herein enable LiPF6 / carbonate solutions (and other salt solutions) to be kept in a purer form for longer periods of time at higher temperatures. This is a huge benefit to the industry. It allows LiPF6-based components to have a longer shelf life in the supply chain itself (pre-manufacturing), thereby providing suppliers with more leeway in balancing inventory for just-in-time manufacturing customers. Because goods can be stored for longer periods of time without deterioration, the timely flow of products in the supply chain is greatly improved. It also improves the shelf life of products (batteries and other charge storage devices, such as capacitors) using the electrolyte composition of the present invention.

[0172] Therefore, the present invention also discloses a method for reducing the degradation of a salt / carbonate solution used in an electrolyte formulation or in the prepared electrolyte itself. The method includes adding an amount of an organosilicon compound that inhibits the degradation reaction in the salt / carbonate solution to the salt / carbonate solution. The organosilicon compound can be added to the carbonate solvent before or after the addition of the salt.

[0173] This article describes three exemplary applications of this approach and the benefits of using it:

[0174] First, the production of LiPF6 salts is a highly specialized process that is made more difficult by the extreme reactivity of the salts, especially with water. By introducing the salts into a highly concentrated solution with a simple carbonate solvent as quickly as possible during the production process, a specific amount of OS nitrile material can also be introduced, which stabilizes the solution and prevents degradation by one / both of the two mechanisms described above. This stable LiPF6 solution can be provided as a LiPF6 salt component for use in electrolyte formulations. Formulators will benefit from having a high purity, shelf-stable component that will result in a higher purity final product for the formulated electrolyte.

[0175] For example, in the production process of LiPF6 salt, linear carbonates such as ethyl methyl carbonate (EMC) are often used as solvents. Salt-solvents are stored and shipped to electrolyte manufacturers, who then formulate electrolytes by combining the LiPF6 / linear carbonate solution with other components (such as cyclic carbonates) and other additives to make final battery electrolyte formulations. As defined in the present disclosure, the salt-solvent mixture itself is not considered to be a lithium-ion battery electrolyte because it lacks the necessary components of a functional, commercially acceptable electrolyte. These additional materials are necessary to produce a suitable interface on the lithium-ion battery active material to maximize the performance of the battery. Therefore, a salt-solvent mixture is disclosed herein, which comprises a LiPF6 salt, a linear carbonate (such as EMC) and an OS material that inhibits degradation reactions in the salt-solvent mixture. As OS is added to the salt-solvent mixture, the shelf life of the salt-solvent mixture is significantly extended. For example, a salt-solvent mixture with an OS material added can be stored for more than 6 months and can still be formulated into a commercially acceptable lithium-ion battery electrolyte.

[0176] The second exemplary use involves the introduction of a specific amount of OS nitrile material into the formulated electrolyte itself. Again, the stability of the formulated electrolyte is enhanced, allowing for greater tolerance to any unintentional moisture or unintentional temperature storage conditions. The overall lithium battery production process is improved by providing battery manufacturers with greater flexibility (in terms of the shelf life of the desired components and the ultimate useful life of the electrolyte formulation).

[0177] The third exemplary application relates to a method for preparing a salt-solvent and electrolyte solution. In essence, the salt is mixed into a solvent or a solvent mixture. The mixing heat of a salt (such as LiPF6) in a carbonate solvent (such as EMC, DMC or DEC) is extremely high. Therefore, during the mixing process, hot spots may be generated locally. The temperature increase in these hot spot areas may stimulate the aforementioned degradation reactions. In today's electrolyte production methods, heat is removed by active thermal management, and great attention is paid to preventing hot spots from being generated during the electrolyte preparation process. This mitigation measure increases the cost and complexity of electrolyte preparation. Here, we disclose a new method to overcome these mixing challenges. By first mixing the OS material (of the present invention) into a carbonate solvent before adding the salt, temperature-induced degradation reactions can be eliminated or reduced.

[0178] Silicone compounds:

[0179] The present disclosure includes a class of materials, organosilicon (OS) compounds, that inhibit the degradation pathways of electrolyte salts by interacting with the salts in simple or complex solvent systems.

[0180] Preferred OS compounds are selected from the group consisting of:

[0181] (R) 4- a-Si-(Sp-Y) a -Z b (Formula I)

[0182] in:

[0183] "a" is an integer from 1 to 4; "b" is an integer from 0 to (3×a);

[0184] "Z", absent when "b" = 0, is selected from the group consisting of "R" and:

[0185]

[0186] Wherein each "R" is independently selected from the group consisting of halogen, C 1-6 A straight-chain or branched alkyl, alkenyl or alkynyl group and a C 1-6 a straight-chain or branched haloalkyl, haloalkenyl or haloalkynyl group;

[0187] Each "Sp" in Formula I and Formula II is independently selected from C 1-15 Straight or branched chain alkylene and C 1-15 A group consisting of a straight chain or branched chain halogenated alkylene group; and

[0188] Each "Y" in Formula I is independently selected from the group consisting of organic polar groups.

[0189] In some forms of these compounds, each "Y" is independently an organic polar group selected from the group consisting of:

[0190]

[0191]

[0192] The bent bond represents C 2-6 Alkylene bridging moiety.

[0193] In a more limited form of the compound, each "Y" is independently an organic polar group selected from the group consisting of:

[0194]

[0195] Furthermore, each "Y" may optionally and independently be an organic polar group selected from the group consisting of: In an alternative form of this compound, "a" is 1 and "b" is 0-2; optionally, "b" is 1 and "Z" is R. In this form, an optional embodiment is that at least one "R" is fluorine, and each "Sp" is independently selected from C which may be fluorinated. 1-6 A group consisting of a straight chain or branched chain alkylene group.

[0196] In another alternative form of this compound, "a" is 2 and "b" is 0-6; optionally, "b" is 1 and "Z" is R. In this form, an optional embodiment is that at least one "R" is fluorine, and each "Sp" is independently selected from C which may be fluorinated. 1-6 A group consisting of a straight chain or branched chain alkylene group.

[0197] In another alternative form of this compound, "a" is 3 and "b" is 0-9; optionally, "b" is 1 and "Z" is R. In this form, an optional embodiment is that at least one "R" is fluorine, and each "Sp" is independently selected from C which may be fluorinated. 1-6 A group consisting of a straight chain or branched chain alkylene group.

[0198] In another alternative form of this compound, "a" is 4 and "b" is 0-12; optionally, "b" is 1 and "Z" is R. In this form, an optional embodiment is that at least one "R" is fluorine, and each "Sp" is independently selected from C which may be fluorinated. 1-6 A group consisting of a straight chain or branched chain alkylene group.

[0199] By virtue of the nature of the subscripts "a" and "b", the following general structures are expressly within the scope of the compounds disclosed and claimed herein:

[0200]

[0201] Each R group is as defined above for "R"; Sp is as defined above, and Y is as defined above.

[0202] When the polar group Y has a valence of two (2) or more, it will have more than one substitution site. Thus, there may be more than one silicon atom bonded to Y via a spacer group, as described above in the definition of Z. Thus, the following structure is also explicitly within the scope of the compounds disclosed and claimed herein:

[0203] wait.

[0204] In all forms of the compounds, "halogen" includes fluorine, chlorine, bromine and iodine. Fluorine and chlorine are preferred halogen substituents.

[0205] A subgroup of OS compounds disclosed herein are FnSnMN compounds having the following general formula:

[0206]

[0207] Where R 1 , R 2 and R 3are the same or different and are independently selected from the group consisting of C1 to C6 linear or branched alkyl, alkenyl, alkynyl or halogen (preferably F), "spacer" is C1 to C6 linear or branched alkylene (preferably C1 to C6 linear divalent alkylene). And Y is a polar organic part as described above.

[0208] The compounds disclosed herein can be prepared by many different routes. The general methods that can be used to make the compounds are as follows:

[0209]

[0210] R 1 , R 2 and R 3 The group is as defined in R herein; R 4 Has the same definition as Y; "n" is a positive integer.

[0211] The compounds disclosed herein can also be prepared by the following method:

[0212]

[0213] Likewise, R 1 , R 2 and R 3 The group is as defined in R herein; R 4 Has the same definition as Y. The compounds disclosed herein are also prepared by a number of specific routes, including the following reaction schemes:

[0214]

[0215] (R 4 As defined above for Y),

[0216]

[0217] (R 4 As defined above for Y),

[0218]

[0219] (R 4 as defined above for Y).

[0220] The presently disclosed compounds are organosilicon compounds having a common structural feature in the form of one or more terminal or internal polar organic substituents or moieties. As used herein, the terms "polar organic substituent" and "polar organic moiety" are used interchangeably. These terms expressly include, but are not limited to, the following functional groups:

[0221]

[0222]

[0223] Preferred compounds include the following structures:

[0224]

[0225]

[0226]

[0227] The above structures are all described with terminal cyano groups. This is for simplicity purposes only. Similar compounds having internal and / or terminal polar moieties replacing the cyano moiety as described above are clearly within the scope of the present disclosure. Similarly, halogenated compounds are described above as fluorinated compounds. Similar compounds having other halogen substituents (chlorine, bromine and / or iodine) replacing the fluorine atom are clearly within the scope of the present disclosure. For each compound listed, two optional systematic names are provided (the first in each pair of names designates the basic core as nitrile; the second designates the basic core as silane). In addition, each compound has an abbreviated name, where DF=difluoro, TF=trifluoro, "Sn" represents an alkylene spacer between the silicon atom and the terminal cyanate, isocyanate or thiocyanate moiety and "n" represents the number of carbon atoms in the spacer.

[0228] The synthesis of similar sulfones can be accomplished using the exemplary syntheses of the following designated compounds 1NMS, F1S3MS and DF1S3MS. Note that other sulfones falling within the broader disclosure contained herein can be prepared by the same route by simply changing the starting reagents accordingly.

[0229] The synthesis process of 1NMS is as follows: 2-(methylsulfonyl)ethanol is mixed with 0.5 mol equivalent of hexamethyldisilazane and about 1 mol equivalent % of Al(H2PO4)3 as a catalyst without using a solvent. The mixture is kept at about 80°C overnight and distilled twice to obtain pure 1NMS.

[0230]

[0231] The synthesis process of F1S3MS is as follows: Allyl methyl sulfide is dissolved in ethanol and mixed with 4 mol equivalents of H2O2. About 3 mol% equivalents of ammonium heptamolybdate are added as an oxidation catalyst. The next day, the solution is neutralized with NaHCO3 solution and extracted with CH2Cl2, the water portion is discarded, and the organic layer is evaporated and distilled to obtain allyl methyl sulfone. Allyl methyl sulfone is hydrogenated with dimethylchlorosilane using Karstedt's catalyst. The product is fluorinated using NaFHF at about 150°C, filtered, distilled twice, and dried over molecular sieves to obtain pure F1S3MS.

[0232]

[0233] The synthesis process of DF1S3MS is as follows: 3-Mercaptopropylmethyldimethoxysilane is dissolved in ethanol and mixed with one (1) mol equivalent of NaOH aqueous solution. Then one (1) mol equivalent of Me2SO4 is added to the mixture and refluxed overnight. The solid is filtered off. The crude product is oxidized with 4 mol equivalents of H2O2 and 3 mol% equivalents of ammonium heptamolybdate. The solvent is evaporated and 2 mol equivalents of HF aqueous solution are added. The product is extracted with CH2Cl2 and distilled.

[0234]

[0235] F1S3MN Synthesis:

[0236] Scheme 1 describes the synthesis scheme of F1S3MN. [F] represents a fluorinating agent, such as HF, NH4FHF or other fluorinating agents. NH4FHF is preferably used as the fluorinating agent for laboratory scale synthesis. If HF is used, the only byproduct is HCl. The synthesized F1S3MN compound is washed from the solid salt with hexane, distilled, dried with CaO, and distilled again.

[0237]

[0238] Scheme 2 describes the synthesis of F1S3MN using NH4FHF as the fluorinating agent. Using Karstedt's catalyst (Platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex solution, Cat. No. 479519, Sigma-Aldrich, St. Louis, MO), about 3% substitution occurs on the secondary carbon, producing isoF1S3MN. isoF1S3MN has a lower boiling point than F1S3MN and most of it can be separated by fractional distillation.

[0239]

[0240] Scheme 3 describes an alternative, shorter synthetic scheme for F1S3MN using the Cl1S3MN intermediate. The Cl1S3MN intermediate can be obtained from Gelest, Inc. (Product Code SIC2452.0, 11 East Steel Road, Morrisville, PA). The use of the Cl1S3MN intermediate reduces the time spent in the synthetic process.

[0241]

[0242] Scheme 4 describes another synthesis of F1S3MN. As in Scheme 1, [F] represents a fluorinating agent, such as HF, NH4FHF or other fluorinating agents. The use of HF as a fluorinating agent in this synthesis will not produce solid byproducts, so hexane extraction and filtration of solids are not required. The only byproduct is HCl.

[0243]

[0244] Scheme 5 depicts another synthetic scheme for F1S3MN. As in Scheme 1, [F] represents a fluorinating agent, such as HF, NH4FHF or other fluorinating agents.

[0245]

[0246] Synthesis of F1S3MN:

[0247] In a preferred route, allyl cyanide is heated to about 100°C with a small amount of Karstedt's catalyst. Dimethylchlorosilane is added dropwise and refluxed for 4 hours. After cooling to room temperature, the mixture is fluorinated at room temperature with 1 mol equivalent of ammonium bifluoride. Cold hexane is added to the mixture, the solid is filtered off and the solvent is evaporated. Calcium oxide is added to the crude product and distilled at 45-55°C and 0.4 torr vacuum to obtain the desired product, F1S3MN.

[0248] Synthesis of F1S3ME:

[0249]

[0250] In the preferred route, allyl acetate is mixed with dimethylsilyl chloride and a small amount of Karstedt's catalyst is added. The mixture is allowed to react overnight. The next day, the mixture is fluorinated with 0.33 mol equivalent of antimony trifluoride at room temperature overnight with vigorous stirring. The next day, the solid is filtered off and the product is distilled at 25-30°C and a vacuum of 0.3 Torr to obtain the desired product, F1S3ME.

[0251] Synthesis of DF1S3DN:

[0252]

[0253] Bis(cyanopropyl)dichlorosilane was mixed with 2 mol equivalents of aqueous HF at room temperature and allowed to react overnight. The crude product was extracted with dichloromethane, the solvent was evaporated, and the product was distilled at 165°C and 0.1 Torr vacuum to obtain the desired product, DF1S3DN.

[0254] Synthesis of 1S3DN:

[0255]

[0256] DF1S3DN was dissolved in THF and cooled with an ice bath, then 2 mol equivalents of methylmagnesium bromide were added and the mixture was allowed to react until it slowly reached room temperature. The mixture was quenched with ethanol, the crude product was extracted with dichloromethane, the solvent was evaporated and the product was distilled at 125°C and 0.2 torr vacuum to obtain the desired product, 1S3DN.

[0257] Synthesis of TF1S3MN:

[0258]

[0259] Cool cyanopropyltrichlorosilane in an ice bath and add 4 mol equivalents of aqueous HF solution dropwise. Allow the mixture to react for no longer than 2 hours. Extract the crude product with dichloromethane, evaporate the solvent and distill the product at 25°C and 0.2 torr vacuum to obtain the desired product, TF1S3MN.

[0260] Synthesis of DPF1S3MN:

[0261]

[0262] Dissolve bis(isopropyl)cyanopropylchlorosilane in THF and cool in an ice bath, then add 1 mol equivalent of HF aqueous solution dropwise and allow the reaction to proceed overnight at room temperature. The next day, evaporate the solvent and distill the product at 60°C and 0.2 Torr vacuum to obtain the desired product, DPF1S3MN.

[0263] Synthesis of DF1S3MSO:

[0264]

[0265] According to the steps, during the synthesis of DF1S3MS, DF1S3MSO was obtained as a byproduct of incomplete oxidation. DF1S3MSO was purified by distillation at 40°C and a vacuum of 0.1 Torr.

[0266] Synthesis of F1S3MA:

[0267]

[0268] In this synthesis, 2 mol equivalents of dimethylallylamine were mixed with 1,1,3,3-tetramethyldisiloxane and a small amount of Karstedt's catalyst. The mixture was heated to 100 °C and allowed to react overnight. The next day, the mixture was fluorinated with 0.67 mol equivalents of antimony trifluoride at 150 °C overnight with vigorous stirring. The next day, the solids were filtered off and the product was distilled at 20-25 °C and a vacuum of 0.2 Torr to obtain the desired product, F1S3MA.

[0269] Synthesis of F1S3MC:

[0270]

[0271] Allyl alcohol was silylated with hexamethyldisilazane at 80°C overnight using a catalytic amount of aluminum dihydrogen phosphate. Prior to hydrosilylation, the intermediate allyloxytrimethylsilane was distilled to purify it. Hydrosilylation was performed overnight at 80°C with 1 mol equivalent of dimethylchlorosilane and a small amount of Karstedt's catalyst. The next day, the mixture was fluorinated and hydrolyzed at room temperature with 2 mol equivalents of aqueous hydrofluoric acid under vigorous stirring to give (3-hydroxypropyl)dimethylfluorosilane, which was distilled before the next step. The final intermediate was dissolved in hexane, 1 mol equivalent of trimethylamine was added, the mixture was cooled in an ice bath and methyl chloroformate was added dropwise to the mixture, which was then allowed to react overnight at room temperature. The next day, the solid was filtered off, the solvent was evaporated and the product was distilled at 28°C and a vacuum of 0.2 torr to give the desired product, F1S3MC.

[0272] Synthesis of DF1S3MN:

[0273]

[0274] Commercial 3-cyanopropyldichloromethylsilane (CAS No. 1190-16-5; Sigma Aldrich, St. Louis, MO, US) was fluorinated with ammonium bifluoride at room temperature. Cold hexane was then added to the mixture. The solid was filtered off and the solvent was evaporated. Calcium oxide was added to the crude product. The solvent was distilled at 35-45° C. and 0.4 torr vacuum to obtain the desired product with very high purity (~99.8%) and approximately 90% yield.

[0275] Synthesis of DF1S2MN:

[0276]

[0277] Acrylonitrile is mixed with N,N,N',N'-methylethylenediamine and copper (I) oxide in a flask and heated to 60°C. Dichloromethylsilane is then added dropwise and refluxed overnight. After cooling to room temperature, the mixture is distilled under vacuum (43°C, 0.2 Torr) to obtain the dichloro intermediate (DCl1S2MN). The intermediate is fluorinated with 1.2 mol equivalents of ammonium bifluoride at room temperature or with 1.2 mol equivalents of sodium bifluoride at 130°C. Dichloromethane is then added and the solid is filtered off. The solvent is evaporated and the crude product is distilled under vacuum. Triethylamine and molecular sieves are added to the product and distilled at 25-33°C and 0.1 Torr vacuum to obtain the desired product in very high purity (>99%) with a yield of about 75%.

[0278] 1ND1N Synthesis:

[0279] Scheme 16 describes the synthesis of 1ND1N. 1ND1N cannot be chemically dried using sodium (Na), calcium oxide (CaO), or calcium hydride (CaH2).

[0280]

[0281] Example

[0282] Effect of temperature:

[0283] Figure 1A The reduction in HF production in the salt-solvent mixture containing OS nitrile is shown compared to the autocatalytic HF formation in the carbonate-based control mixture without OS nitrile at 100°C. In the case of the OS moiety, the HF concentration was close to zero after 20 days of storage at 100°C. The production and removal of HF at lower temperatures were studied.

[0284] like Figure 3A As shown, there is no obvious autocatalytic effect on HF production at 70 °C. Kinetic modeling suggests that the rate constant for HF production at 70 °C is about 4 times lower than that at 100 °C.

[0285] The storage stability of the salt-solvent mixtures containing OS nitrile was then tested at lower temperatures compared to electrolytes without OS nitrile. No visible H + Clear( Figure 3B When the OS nitrile-containing salt-solvent mixtures containing F1S3MN or DF1S2MN were stored at 45°C, no visible H + Clear( Figure 3C However, after 141 days, some H + clear, although all mixtures with 500 ppm water added showed a decrease in HF ( Figure 3C ).

[0286] Influence of compound structure:

[0287] OS nitriles other than F1S3MN were also tested for H + Effect of clearance. The compounds tested included 1S2MN, 1S3MN, F1S2MN, DF1S2MN, DF1S3MN, and TF1S2MN, and the results were compared with F1S3MN. Figure 4A and Figure 4B All OS nitriles tested are shown in Figure 2 for 100 °C H + Clear.

[0288] OS Nitrile to H +The removal of H was also compared with other nitriles, including succinonitrile, adiponitrile, and valeronitrile. The results showed that other nitriles removed H at 100 °C. + ( Figure 5A ), but is less stable and has more decomposition than OS nitrile F1S3MN ( Figure 5B ).

[0289] In addition, the trifluoro structure was evaluated for H + Specifically, nitrile and non-nitrile compounds with trifluoro structures, including TF1S2MN, TF-BN, and TF1S6M (non-nitrile) ( Figure 6 The results show that nitriles with trifluoro structures can remove H at 100 °C. + , but the non-nitrile compound TF1S6M does not scavenge H + ( Figure 6 ).

[0290] Effect of carbonate mixture:

[0291] In this example, the H ions of carbonate mixtures to OS nitrile were examined. + In EC blends with a dielectric constant of 89, H + The clearance depended on the concentration of F1S3MN. At 1-2% F1S3MN, no H + , while higher concentrations of F1S3MN showed increased H + Clearance Fig. 7A Similar results were obtained with an EC / PC blend having a dielectric constant of 76.9 (data not shown).

[0292] Next, EC / DEC blends with a dielectric constant of 21.8 were studied. The results showed that since EC / DEC blends have a much lower dielectric constant than EC or EC / PC, the lack of OS led to a rapid increase in HF concentration; however, with the addition of OS, the HF concentration decreased significantly ( Figure 7B ).

[0293] For the high salt EMC mixture, when no OS nitrile was added, the concentration of HF increased significantly for the control sample with nominal and 500 ppm water added and stored at 100 °C ( Figure 7C ). After 56 days, the sample was too degraded to be analyzed by NMR. In contrast, when the F1S3MN concentration was about 2%, the addition of OS scavenged H + ( Fig.7D A similar study was performed using a high salt EMC mixture and DF1S2MN, and the minimum DF1S2MN required to achieve the same effect was 1.6% (data not shown).

[0294] Inhibition of HF production:

[0295] In summary, the data clearly demonstrate that the compositions and methods disclosed herein are very effective in inhibiting the production of unwanted HF in salt-solvent mixtures containing fluoride salts such as alkali metal PF6 salts. Figure 1A , the control curve without OS showed HF concentrations ranging from 800-1400 ppm. Figure 1B Results are reported for mixtures containing 2-10% OS, which show no visible HF on the scale of the graph (0-20 ppm). Figure 3A The control curve without OS showed HF concentrations ranging from 800 to 2700 ppm at failure (5-18 days).

[0296] Likewise, see Figure 4A and Figure 4B . Figure 4A Results are shown for a mixture containing 0.13 M OS; it shows no visible HF on the scale of the graph (0-10 ppm). Figure 4B Results are shown for a mixture containing 1 M OS. Over the course of one month, there was no visible HF on the scale of the graph (0-1 ppm).

[0297] Likewise, see Figure 5A , which shows the results for mixtures containing nitrile and non-nitrile OS. All mixtures show no visible HF on the scale of the graph (0-20 ppm).

[0298] Figure 5B It is also noteworthy because it clearly shows that the fluorinated OS nitrile compounds disclosed herein are far superior in stabilizing these types of carbonate mixtures. Figure 5B The nitrile decomposition using various non-OS nitrile compounds (i.e., adiponitrile, succinonitrile, and valeronitrile) was compared with F1S3MN in the presence and absence of water. F1S3MN OS was superior in inhibiting the degradation of the mixture both in the presence (500 ppm water) and in the absence of water.

[0299] Figure 6 Results are shown for controls without OS. These mixtures had HF concentrations > 2000 ppm on day 21. In stark contrast, mixtures containing trifluoroOS nitrile compounds showed no HF.

[0300] Fig. 7AThe inhibition of HF formation was shown to be dependent on the concentration of OS: 1% OS had 1800 ppm HF at 50 days; 2% OS had 200-400 ppm HF at 1 month; 5% OS had 40 ppm HF at 50 days; 8% OS had 30 ppm HF at 50 days; 16% OS had 7 ppm HF at 50 days; 20% OS and 87% OS showed no visible HF on the scale of the graph (0-1 ppm) at 50 days. Figure 7B As shown, the control curve without OS had HF concentrations > 4000 ppm by day 20. In contrast, all OS samples (2%, 5%, 10%, 16%) showed no visible HF (0-20 ppm) at day 20. Figure 7C A control with high salt concentration is shown; after 20 days the HF concentration was 2000 ppm. Fig.7D Results for high salt concentration mixtures are shown. The control, 0.05% OS, and 0.2% OS mixtures all had HF concentrations > 1500 ppm on day 21. In contrast, the mixture with 2% OS showed no visible HF (0-100 ppm).

[0301] These results clearly demonstrate that the mixtures disclosed and claimed herein are effective in stabilizing salt-solvent mixtures comprising a salt, a carbonate solvent, and an organosilicon compound.

Claims

1. A stabilized salt-solvent mixture comprising a salt, a carbonate solvent; and an organosilicon compound, wherein the organosilicon compound inhibits degradation reactions in the salt-solvent mixture.

2. The stabilized salt-solvent mixture according to claim 1, wherein the salt is an alkali metal PF6 salt.

3. The stabilized salt-solvent mixture according to claim 2, wherein the salt is selected from the group consisting of LiPF6 and NaPF6.

4. The stabilized salt-solvent mixture of claim 2, wherein the carbonate is a linear carbonate.

5. The stabilized salt-solvent mixture of claim 2, wherein the carbonate ester is selected from the group consisting of ethyl methyl carbonate, dimethyl carbonate, and diethyl carbonate, ethylene carbonate, propylene carbonate, and gamma-butyrolactone.

6. The stabilized salt-solvent mixture of claim 2, wherein the organosilicon compound is selected from the group consisting of: (R) 4-a -Si-(Sp-Y) a -Z b (Formula I) in: "a" is an integer from 1 to 4; "b" is an integer from 0 to (3×a); "Z", absent when "b" = 0, selected from the group consisting of "R" and: Wherein each "R" is independently selected from the group consisting of halogen, C 1-6 A straight-chain or branched alkyl, alkenyl or alkynyl group and a C 1-6 a straight-chain or branched haloalkyl, haloalkenyl or haloalkynyl group; Each "Sp" in Formula I and Formula II is independently selected from C 1-15 Straight or branched chain alkylene and C 1-15 A group consisting of a straight chain or branched chain halogenated alkylene group; and Each "Y" in Formula I is independently selected from the group consisting of organic polar groups.

7. The stabilized salt-solvent mixture of claim 6, wherein each "Y" is independently an organic polar group selected from the group consisting of: The bent bond represents C 2-6 Alkylene bridging moiety.

8. The stabilized salt-solvent mixture of claim 7, wherein each "Y" is independently an organic polar group selected from the group consisting of:

9. The stabilized salt-solvent mixture of claim 2, wherein the organosilicon compound is:

10. The stabilized salt-solvent mixture of claim 2, wherein the organosilicon compound is:

11. The stabilized salt-solvent mixture according to any one of claims 1 to 10 for use in an electrolyte formulation.

12. A stabilized salt-solvent mixture comprising an alkali metal PF6 salt, a carbonate solvent; and an organosilicon compound selected from the group consisting of: (R) 4-a -Si-(Sp-Y) a -Z b (Formula I) in: "a" is an integer from 1 to 4; "b" is an integer from 0 to (3×a); "Z", absent when "b" = 0, selected from the group consisting of "R" and: Wherein each "R" is independently selected from the group consisting of halogen, C 1-6 A straight-chain or branched alkyl, alkenyl or alkynyl group and a C 1-6 a straight-chain or branched haloalkyl, haloalkenyl or haloalkynyl group; Each "Sp" in Formula I and Formula II is independently selected from C 1-15 Straight or branched chain alkylene and C 1-15 A group consisting of a straight chain or branched chain halogenated alkylene group; and Each "Y" in Formula I is independently selected from the group consisting of: The bent bond represents C 2-6 an alkylene bridging moiety; The organosilicon compound inhibits degradation reactions in the salt-solvent mixture.

13. The stabilized salt-solvent mixture of claim 12, wherein the carbonate is selected from the group consisting of ethyl methyl carbonate, dimethyl carbonate, and diethyl carbonate, ethylene carbonate, propylene carbonate, and gamma-butyrolactone.

14. The stabilized salt-solvent mixture of claim 12, wherein each "Y" is independently an organic polar group selected from the group consisting of:

15. The stabilized salt-solvent mixture of claim 12, wherein the organosilicon compound is:

16. The stabilized salt-solvent mixture of claim 12, wherein the organosilicon compound is:

17. The stabilized salt-solvent mixture of claim 12, wherein the salt is selected from the group consisting of LiPF6 and NaPF6.

18. The stabilized salt-solvent mixture according to any one of claims 12 to 17 for use in an electrolyte formulation.

19. A method of mitigating degradation of a salt / carbonate solution used in an electrolyte formulation or in a formulated electrolyte, the method comprising adding to the salt / carbonate solution an amount of an organosilicon compound selected from the group consisting of: (R) 4-a -Si-(Sp-Y) a -Z b (Formula I) in: "a" is an integer from 1 to 4; "b" is an integer from 0 to (3×a); "Z", absent when "b" = 0, selected from the group consisting of "R" and: Wherein each "R" is independently selected from the group consisting of halogen, C 1-6 A straight-chain or branched alkyl, alkenyl or alkynyl group and a C 1-6 a straight-chain or branched haloalkyl, haloalkenyl or haloalkynyl group; Each "Sp" in Formula I and Formula II is independently selected from C 1-15 Straight or branched chain alkylene and C 1-15 A group consisting of a straight chain or branched chain halogenated alkylene group; and Each "Y" in Formula I is independently selected from the group consisting of: The bent bond represents C 2-6 an alkylene bridging moiety; The organosilicon compound inhibits degradation reactions in the salt-solvent mixture.

20. A stabilized salt-solvent mixture comprising an alkali metal PF6 salt, a carbonate solvent; and an organosilicon compound, wherein the concentration of hydrofluoric acid (HF) in the mixture is less than about 100 ppm after storage at 100°C for 20 days.

21. The stabilized salt-solvent mixture of claim 20, wherein the hydrofluoric acid (HF) concentration in the mixture is less than about 20 ppm after storage at 100°C for 20 days.

22. The stabilized salt-solvent mixture of claim 20, wherein the hydrofluoric acid (HF) concentration in the mixture is less than about 10 ppm after storage at 100°C for 20 days.

23. The stabilized salt-solvent mixture of claim 20, wherein the concentration of hydrofluoric acid (HF) in the mixture is less than about 5 ppm after storage at 100°C for 20 days.

24. The stabilized salt-solvent mixture of claim 20, wherein the organosilicon compound is selected from the group consisting of: (R) 4-a -Si-(Sp-Y) a -Z b (Formula I) in: "a" is an integer from 1 to 4; "b" is an integer from 0 to (3×a); "Z", absent when "b" = 0, selected from the group consisting of "R" and: Wherein each "R" is independently selected from the group consisting of halogen, C 1-6 A straight-chain or branched alkyl, alkenyl or alkynyl group and a C 1-6 a straight-chain or branched haloalkyl, haloalkenyl or haloalkynyl group; Each "Sp" in Formula I and Formula II is independently selected from C 1-15 Straight or branched chain alkylene and C 1-15 A group consisting of a straight or branched chain halogenated alkylene group; and Each "Y" in Formula I is independently selected from the group consisting of: The bent bond represents C 2-6 an alkylene bridging moiety; The organosilicon compound inhibits degradation reactions in the salt-solvent mixture.

25. The stabilized salt-solvent mixture of claim 20, wherein the carbonate is selected from the group consisting of ethyl methyl carbonate, dimethyl carbonate, and diethyl carbonate, ethylene carbonate, propylene carbonate, and gamma-butyrolactone.

26. The stabilized salt-solvent mixture of claim 20, wherein the concentration of the organosilicon compound is calculated using the following formula: Where Vol%OS is the calculated concentration of the organosilicon compound and [ppm H2O] is the measured concentration of water in the salt-solvent mixture. OS is the density of the organosilicon compound, ρ sol is the density of the solvent mixture, MW OS is the molecular weight of the organosilicon compound, MW H2O is the molecular weight of water.

27. The stabilized salt-solvent mixture of claim 20, wherein the organosilicon compound is selected from the group consisting of: (R) 4-a -Si-(Sp-Y) a -Z b (Formula I) in: "a" is an integer from 1 to 4; "b" is an integer from 0 to (3×a); "Z", absent when "b" = 0, selected from the group consisting of "R" and: Wherein each "R" is independently selected from the group consisting of halogen, C 1-6 A straight-chain or branched alkyl, alkenyl or alkynyl group and a C 1-6 a straight-chain or branched haloalkyl, haloalkenyl or haloalkynyl group; Each "Sp" in Formula I and Formula II is independently selected from C 1-15 Straight or branched chain alkylene and C 1-15 A group consisting of a straight or branched chain halogenated alkylene group; and Each "Y" in Formula I is independently selected from the group consisting of: The bent bond represents C 2-6 an alkylene bridging moiety; The organosilicon compound inhibits degradation reactions in the salt-solvent mixture.

28. The stabilized salt-solvent mixture of claim 27, wherein the carbonate is selected from the group consisting of ethyl methyl carbonate, dimethyl carbonate, and diethyl carbonate, ethylene carbonate, propylene carbonate, and gamma-butyrolactone.

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