Dioxazolone and nitrile sulfite as lithium ion battery electrolyte additives

Abstract

Improved battery systems for lithium ion battery based have been developed. The improved system includes a non-aqueous electrolyte comprising one or more lithium salts, one or more non-aqueous solvents, and an additive or additive mixture comprising one or more effective additives selected from a group of disclosed compounds including 3-aryl substituted 1, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13 The compound is prepared from 3-phenyl-1, 3, 2-dioxazole-5-ketone, 3-phenyl-1, 3, 2, 4-dioxathiazole 2-oxide, 2-phenyl-1, 3, 2-dioxazole-5-ketone and 3

Description

[0001] This case is a divisional application of the patent application with application number 201880095997.X filed by the present applicant on August 31, 2018, entitled “Dioxazolone and Nitrile Sulfite Esters as Lithium-ion Battery Electrolyte Additives”. The entire contents of the parent case are incorporated into this divisional application by reference.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Patent Application No. 16 / 045,082, filed on July 25, 2018, and U.S. Provisional Patent Application No. 62 / 687,594, filed on June 20, 2018, the entire contents of which are incorporated herein by reference. Technical Field

[0004] The present disclosure relates to rechargeable battery systems and, more particularly, to the chemistry of rechargeable lithium-ion battery systems including effective electrolyte additives for improving the performance of such systems. Background Art

[0005] Rechargeable batteries are an integral component of energy storage systems for electric vehicles and grid storage (e.g., for backup power during power outages, as part of a microgrid, etc.). Lithium-ion based batteries are a common type of rechargeable battery.

[0006] Electrolyte additives have been shown to be effective in improving the life and performance of lithium-ion-based batteries. For example, JC Burns et al., Journal of the Electrochemical Society, 160, A1451 (2013) demonstrated that five proprietary, undisclosed electrolyte additives can improve cycle life compared to electrolyte systems without or with only one additive. Other studies focus on the performance improvements brought about by electrolyte systems containing three or four additives described in US2017 / 0025706. However, researchers are generally unaware of the interactions between different additives that enable them to synergize with the electrolyte and specific positive and negative electrodes. Therefore, the identity of certain systems is usually based on repeated trials and cannot be predicted in advance.

[0007] Previous studies have not found such a dual-additive electrolyte system: it can be combined into a lithium-ion battery system to produce a system that is robust enough for grid or electric vehicle applications. As described in US2017 / 0025706, the performance of the studied dual-additive systems (such as 2% VC + 1% allyl methanesulfonate and 2% PES + 1% TTSPi) is generally worse than that of the three-additive and four-additive electrolyte systems. (For example, see Tables 1 and 2 of US2017 / 0025706.) US2017 / 0025706 discloses that in order to produce a robust lithium-ion battery system, a third compound must be used at a concentration of 0.25-3% by weight, which is usually tris (-trimethyl-silyl) -phosphate (TTSP) or tris (-trimethyl-silyl) -phosphite (TTSPi). (See, e.g., US 2017 / 0025706, paragraph 72.) However, because additives are expensive and difficult to include in lithium-ion batteries at a manufacturing scale, there is a need for simpler yet more efficient battery systems, including those with fewer additives.

[0008] To further advance the adoption of electric vehicles and grid energy storage applications, it is desirable to develop lithium-ion battery chemistries that provide longer life at high temperatures and high cell voltages without significantly increasing costs. The introduction of sacrificial electrolyte additives in amounts of several weight percent is a practical approach to form a protective solid electrolyte interphase (SEI) layer that limits electrolyte decomposition during storage and operation of the battery. In recent years, a large number of such additives that can be used to improve battery performance for various applications have been obtained through extensive efforts. Examples are vinylene carbonate (VC), fluoroethylene carbonate (FEC), prop-1-ene-1,3-sultone (PES), vinyl sulfate (1,3,2-dioxathiolane-2,2-dioxide, DTD) and lithium difluorophosphate (LFO).

[0009] The present application provides compositions for use as electrolyte additives in lithium-ion battery systems.

[0010] definition

[0011] "Cell" or "battery cell" generally refers to an electrochemical cell, which is a device capable of generating electrical energy from a chemical reaction or promoting a chemical reaction by introducing electrical energy. A battery may contain one or more cells.

[0012] A "rechargeable battery" generally refers to a type of battery that can be charged, discharged into a load, and can be recharged multiple times. In this application, multiple examples are described based on lithium-ion rechargeable batteries. However, embodiments of the present invention are not limited to one type of rechargeable battery and can be applied in conjunction with various rechargeable battery technologies. Summary of the invention

[0013] The present disclosure encompasses new battery systems with less effective electrolyte additives that can be used in different energy storage applications, for example, in vehicles and grid storage. More specifically, the present disclosure includes additive electrolyte systems that improve the performance and life of lithium-ion batteries while reducing the cost of other systems that rely on more or other additives. The present disclosure also provides methods for preparing the additives disclosed herein.

[0014] Certain embodiments described herein include a non-aqueous electrolyte for a lithium ion battery comprising at least one lithium salt, at least one non-aqueous solvent, and an additive component comprising at least one effective additive selected from

[0015] (a) 3-aryl substituted 1,4,2-dioxazol-5-one compounds according to formula (I):

[0016]

[0017] wherein R is any aromatic substituent, any unsaturated aliphatic substituent or any aliphatic substituent containing one or more fluorine atoms; or

[0018] (b) 3-CRR'R" substituted 1,4,2-dioxazol-5-one compounds according to formula (II):

[0019]

[0020] wherein R, R' and R" are each hydrogen, an alkyl substituent or an aromatic substituent; or

[0021] (c) R-substituted nitrile sulfite compounds according to formula (III):

[0022]

[0023] wherein R is any alkyl or aromatic substituent.

[0024] In certain further embodiments, the at least one effective additive is 0.01-6 wt % based on the total weight of the electrolyte solution. In other embodiments, the at least one effective additive is 0.25-5 wt % based on the total weight of the electrolyte solution. In other embodiments, the concentration of the at least one effective additive is about 2 wt %.

[0025] In other embodiments, the additive component comprises ethylene sulfate, lithium difluorophosphate, vinylene carbonate and / or fluoroethylene carbonate. In further embodiments, the additive component comprises 3-phenyl-1,4,2-dioxazol-5-one.

[0026] In certain embodiments, the at least one non-aqueous solvent is a carbonate solvent. In further embodiments, the carbonate solvent is ethylene carbonate or dimethyl carbonate. In further embodiments, the non-aqueous solvent comprises at least 2 non-aqueous solvents.

[0027] In other embodiments, a lithium ion battery is provided, comprising a negative electrode; a positive electrode; a non-aqueous electrolyte comprising a lithium salt dissolved in at least one non-aqueous solvent and an additive component, wherein the additive component comprises at least one effective additive from the following:

[0028] (a) 3-aryl substituted 1,4,2-dioxazol-5-one compounds according to formula (I):

[0029]

[0030] wherein R is any aromatic substituent, any unsaturated aliphatic substituent or any aliphatic substituent containing one or more fluorine atoms; or

[0031] (b) 3-CRR'R" substituted 1,4,2-dioxazol-5-one compounds according to formula (II):

[0032]

[0033] wherein R, R' and R" are each hydrogen, an alkyl substituent or an aromatic substituent; or

[0034] (c) R-substituted nitrile sulfite compounds according to formula (III):

[0035]

[0036] wherein R is any alkyl or aromatic substituent.

[0037] In certain further embodiments, the at least one effective additive is 0.01-6 wt % based on the total weight of the electrolyte solution. In other embodiments, the at least one effective additive is 0.25-5 wt % based on the total weight of the electrolyte solution. In other embodiments, the concentration of the at least one effective additive is about 2 wt %.

[0038] In other embodiments, the additive component comprises ethylene sulfate, lithium difluorophosphate, vinylene carbonate and / or fluoroethylene carbonate. In further embodiments, the additive component comprises 3-phenyl-1,4,2-dioxazol-5-one.

[0039] In certain embodiments, the at least one non-aqueous solvent is a carbonate solvent. In further embodiments, the carbonate solvent is ethylene carbonate or dimethyl carbonate. In further embodiments, the non-aqueous solvent comprises at least 2 non-aqueous solvents.

[0040] In other embodiments, the lithium ion battery has an initial capacity retention rate of 95% after 200 cycles between 3.0V and 4.3V at a charge rate of C / 3CCCV at 40°C. In further embodiments, the lithium ion battery has an initial capacity retention rate of 95% after 400 cycles between 3.0V and 4.3V at a charge rate of C / 3CCCV at 40°C.

[0041] In another aspect, an electric vehicle with a rechargeable battery is provided, which includes a drive motor, a gearbox, an electronic device and a battery system. The battery system includes a negative electrode, a positive electrode and a non-aqueous electrolyte, the non-aqueous electrolyte comprising a lithium salt dissolved in at least one non-aqueous solvent, and an additive component, the additive component including at least one effective additive from the following:

[0042] (a) 3-aryl substituted 1,4,2-dioxazol-5-one compounds according to formula (I):

[0043]

[0044] wherein R is any aromatic substituent, any unsaturated aliphatic substituent or any aliphatic substituent containing one or more fluorine atoms; or

[0045] (b) 3-CRR'R" substituted 1,4,2-dioxazol-5-one compounds according to formula (II):

[0046]

[0047] wherein R, R' and R" are each hydrogen, an alkyl substituent or an aromatic substituent; or

[0048] (c) R-substituted nitrile sulfite compounds according to formula (III):

[0049]

[0050] wherein R is any alkyl or aromatic substituent.

[0051] In certain further embodiments, the at least one effective additive is 0.01-6 wt % based on the total weight of the electrolyte solution. In other embodiments, the at least one effective additive is 0.25-5 wt % based on the total weight of the electrolyte solution. In other embodiments, the concentration of the at least one effective additive is about 2 wt %.

[0052] In other embodiments, the additive component comprises ethylene sulfate, lithium difluorophosphate and / or vinylene carbonate. In further embodiments, the additive component comprises 3-phenyl-1,4,2-dioxazol-5-one.

[0053] In certain embodiments, the at least one non-aqueous solvent is a carbonate solvent. In further embodiments, the carbonate solvent is ethylene carbonate or dimethyl carbonate. In further embodiments, the non-aqueous solvent comprises at least 2 non-aqueous solvents.

[0054] In other embodiments, the battery system has an initial capacity retention rate of 95% after 200 cycles at a charge rate of C / 3CCCV between 3.0V and 4.3V at 40°C. In further embodiments, the battery system has an initial capacity retention rate of 95% after 400 cycles at a charge rate of C / 3CCCV between 3.0V and 4.3V at 40°C.

[0055] The present invention also includes the following items:

[0056] 1. A non-aqueous electrolyte for a lithium ion battery comprising at least one lithium salt, at least one non-aqueous solvent and an additive component comprising at least one effective additive selected from:

[0057] (a) 3-aryl substituted 1,4,2-dioxazol-5-one compounds according to formula (I):

[0058]

[0059] wherein R is any aromatic substituent, any unsaturated aliphatic substituent or any aliphatic substituent containing one or more fluorine atoms; or

[0060] (b) 3-CRR'R" substituted 1,4,2-dioxazol-5-one compounds according to formula (II):

[0061]

[0062] wherein R, R' and R" are each hydrogen, an alkyl substituent or an aromatic substituent; or

[0063] (c) R-substituted nitrile sulfite compounds according to formula (III):

[0064]

[0065] wherein R is any alkyl or aromatic substituent.

[0066] 2. The non-aqueous electrolyte according to item 1, wherein the concentration of the at least one effective additive is 0.01-6 wt % based on the total weight of the electrolyte solution.

[0067] 3. The non-aqueous electrolyte according to item 1, wherein the concentration of the at least one effective additive is about 2 wt % based on the total weight of the electrolyte solution.

[0068] 4. The non-aqueous electrolyte according to item 1, wherein the additive component comprises ethylene sulfate.

[0069] 5. The non-aqueous electrolyte according to item 1, wherein the additive component comprises lithium difluorophosphate.

[0070] 6. The non-aqueous electrolyte according to item 1, wherein the additive component comprises vinylene carbonate, fluoroethylene carbonate, or a combination thereof.

[0071] 7. The non-aqueous electrolyte according to item 1, wherein the at least one non-aqueous solvent is a carbonate solvent.

[0072] 8. The non-aqueous electrolyte according to item 7, wherein the at least one non-aqueous solvent is selected from ethylene carbonate and dimethyl carbonate.

[0073] 9. The non-aqueous electrolyte according to item 7, further comprising a second non-aqueous solvent.

[0074] 10. The non-aqueous electrolyte according to item 1, wherein the additive component is 3-phenyl-1,4,2-dioxazol-5-one.

[0075] 11. The non-aqueous electrolyte according to item 1, wherein the additive component is a 3-aryl substituted 1,4,2-dioxazol-5-one compound according to formula (I):

[0076]

[0077] wherein R is any aromatic substituent.

[0078] 12. A lithium ion battery comprising:

[0079] negative electrode;

[0080] positive electrode; and

[0081] A non-aqueous electrolyte comprising a lithium salt dissolved in at least one non-aqueous solvent, and an additive component comprising at least one effective additive from:

[0082] (a) 3-aryl substituted 1,4,2-dioxazol-5-one compounds according to formula (I):

[0083]

[0084] wherein R is any aromatic substituent, any unsaturated aliphatic substituent or any aliphatic substituent containing one or more fluorine atoms; or

[0085] (b) 3-CRR'R" substituted 1,4,2-dioxazol-5-one compounds according to formula (II):

[0086]

[0087] wherein R, R' and R" are each hydrogen, an alkyl substituent or an aromatic substituent; or

[0088] (c) R-substituted nitrile sulfite compounds according to formula (III):

[0089]

[0090] wherein R is any alkyl or aromatic substituent.

[0091] 13. The lithium ion battery according to item 12, wherein the concentration of the at least one effective additive is 0.01-6 wt % based on the total weight of the electrolyte solution.

[0092] 14. The lithium ion battery according to item 12, wherein the concentration of the at least one effective additive is 2 wt % based on the total weight of the electrolyte solution.

[0093] 15. The lithium ion battery according to item 12, wherein the additive component comprises ethylene sulfate.

[0094] 16. The lithium ion battery according to item 12, wherein the additive component comprises lithium difluorophosphate.

[0095] 17. The lithium ion battery according to item 12, wherein the additive component comprises vinylene carbonate, fluoroethylene carbonate or a combination thereof.

[0096] 18. The lithium ion battery according to item 12, wherein the non-aqueous solvent is a carbonate solvent.

[0097] 19. The lithium ion battery according to item 18, wherein the at least one non-aqueous solvent is selected from ethylene carbonate and dimethyl carbonate.

[0098] 20. The lithium ion battery according to item 12, wherein the additive component comprises 3-phenyl-1,4,2-dioxazol-5-one.

[0099] 21. The lithium ion battery according to item 12, wherein the additive component is a 3-aryl substituted 1,4,2-dioxazol-5-one compound according to formula (I):

[0100]

[0101] wherein R is any aromatic substituent.

[0102] 22. The lithium ion battery according to item 12, further comprising a second non-aqueous solvent.

[0103] 23. The lithium ion battery according to item 12, wherein after 200 cycles at 40°C with a charge rate of C / 3CCCV between 3.0V and 4.3V, the lithium ion battery has an initial capacity retention rate of 95%.

[0104] 24. The lithium ion battery according to item 12, wherein after 400 cycles at 40°C with a charge rate of C / 3CCCV between 3.0V and 4.3V, the lithium ion battery has an initial capacity retention rate of 95%.

[0105] 25. An electric vehicle with a rechargeable battery, comprising:

[0106] Drive motor;

[0107] Gearbox;

[0108] Electronic equipment; and

[0109] A battery system comprising a negative electrode, a positive electrode and a non-aqueous electrolyte,

[0110] in,

[0111] The non-aqueous electrolyte comprises a lithium salt dissolved in at least one non-aqueous solvent, and an additive component comprising at least one effective additive selected from:

[0112] (a) 3-aryl substituted 1,4,2-dioxazol-5-one compounds according to formula (I):

[0113]

[0114] wherein R is any aromatic substituent, any unsaturated aliphatic substituent or any aliphatic substituent containing one or more fluorine atoms; or

[0115] (b) 3-CRR'R" substituted 1,4,2-dioxazol-5-one compounds according to formula (II):

[0116]

[0117] wherein R, R' and R" are each hydrogen, an alkyl substituent or an aromatic substituent; or

[0118] (c) R-substituted nitrile sulfite compounds according to formula (III):

[0119]

[0120] wherein R is any alkyl or aromatic substituent.

[0121] 26. The electric vehicle according to item 25, wherein the concentration of the at least one effective additive is 0.01-6 wt % based on the total weight of the electrolyte solution.

[0122] 27. The electric vehicle according to item 25, wherein the concentration of the at least one effective additive is 2 wt % based on the total weight of the electrolyte solution.

[0123] 28. The electric vehicle according to item 25, wherein the additive component comprises ethylene sulfate.

[0124] 29. The electric vehicle of item 25, wherein the additive component comprises lithium difluorophosphate.

[0125] 30. The electric vehicle according to item 25, wherein the additive component comprises vinylene carbonate, fluoroethylene carbonate or a combination thereof.

[0126] 31. The electric vehicle according to item 25, wherein the non-aqueous solvent is a carbonate solvent.

[0127] 32. The electric vehicle according to item 25, wherein the at least one non-aqueous solvent is selected from ethylene carbonate and dimethyl carbonate.

[0128] 33. The electric vehicle according to item 25, wherein the additive component comprises 3-phenyl-1,4,2-dioxazol-5-one.

[0129] 34. The electric vehicle according to item 25, wherein the additive component is a 3-aryl substituted 1,4,2-dioxazol-5-one compound according to formula (I):

[0130]

[0131] wherein R is any aromatic substituent.

[0132] 35. The electric vehicle according to item 25, further comprising a second non-aqueous solvent.

[0133] 36. The electric vehicle of item 25, wherein the battery system has an initial capacity retention of 95% after 200 cycles at 40°C with a charge rate of C / 3CCCV between 3.0V and 4.3V.

[0134] 37. The electric vehicle according to item 25, wherein the battery system has an initial capacity retention rate of 95% after 400 cycles between 3.0 V and 4.3 V at a charge rate of C / 3 CCCV at 40°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0135] Figure 1 is a schematic diagram of a vehicle including a battery storage system.

[0136] Figure 2 is a schematic diagram of an exemplary battery storage system.

[0137] Figure 3 is a schematic diagram of a lithium-ion battery cell system.

[0138] Figure 4 is 3-methyl-1,4,2-dioxazol-5-one (MDO) synthesized as described herein 1 HNMR spectrum.

[0139] Figure 5 is the MDO synthesized as described herein 13 C NMR spectrum.

[0140] Figure 6 is the FTIR spectrum of MDO synthesized as described herein.

[0141] Figure 7 3-phenyl-1,4,2-dioxazol-5-one (PDO) synthesized as described herein 1 HNMR spectrum.

[0142] Figure 8 is the PDO synthesized as described herein 13 C NMR spectrum.

[0143] Fig. 9 is the FTIR spectrum of PDO synthesized as described herein.

[0144] Fig.10is benzonitrile sulfite (BS) synthesized as described herein 1 H NMR spectrum.

[0145] Fig.11 BS synthesized as described herein 13 C NMR spectrum.

[0146] Fig.12 is the FTIR spectrum of BS synthesized as described herein.

[0147] Fig.13 Differential capacitance (dQ / dV) plots of cell formation in NMC622B / graphite (left) and NMC532 / graphite (right) cells are shown. The electrolyte solution contained either (a) MDO-based, (b) PDO-based, or (c) BS-based additive mixtures. A "control" cell without any additives was prepared for comparison.

[0148] Fig.14 Shown are the cell volume changes caused by gas generation during (a) storage at 4.3 V for 500 hours at 60°C and (b) cell formation to 4.3 V in NMC622B / graphite (left) and NMC532 / graphite (right) cells. The electrolyte solutions contained either MDO-based, PDO-based or BS-based additive mixtures.

[0149] Fig.15 Shown are the cell voltages measured for NMC622 / graphite (left) and NMC532 / graphite (right) battery cells during open circuit storage for 500 hours at 60° C. As shown, the electrolyte solution contained (a) MDO-based, (b) PDO-based, or (c) BS-based additive mixtures.

[0150] Fig.16 Figure 2 shows the R after (a) storage at 60°C for 500 hours and (b) cell formation to 4.3 V in NMC622 / graphite (left) and NMC532 / graphite (right) cells. ct As shown at the bottom of the figure, the electrolyte solution contains either MDO-based, PDO-based or BS-based additive blends.

[0151] Fig.17 (ac) show the normalized discharge capacity and (df) ΔV of NMC622 / graphite pouch cells cycled to 4.3 V at C / 3 charge / discharge rate at 40° C. Electrolyte additive concentrations are shown.

[0152] Fig.18(ac) show the normalized discharge capacity and (df) ΔV of a NMC532 / graphite pouch cell cycled to 4.3 V at a charge / discharge rate of C / 3 at 40° C. Electrolyte additive concentrations are as indicated.

[0153] Fig.19 Shows the Fig.15 The PDO-containing cell shown in b was charged to 4.3 V and stored at 60° C. in an open circuit state for another 500 hours. The cell voltage of (a) NMC622 / graphite and (b) NMC532 / graphite cells was measured during open circuit storage at 60° C. for 500 hours. The PDO-based additive mixture is shown in the figure. DETAILED DESCRIPTION

[0154] Figure 1 Basic components of a battery powered electric vehicle (EV) 100 are shown. The EV 100 includes at least one drive motor (traction motor) 102A and / or 102B, at least one gearbox 104A and / or 104B coupled to the respective drive motor 102A and / or 102B, a battery unit 106, and electronics 108. In general, the battery unit 106 provides power to power the power electronics of the EV 100 and to propel the EV 100 using the drive motor 102A and / or 102B. The EV 100 includes numerous other components not described herein but known to a skilled person or persons of ordinary skill. Although shown Figure 1 The electric vehicle 100 is constructed with four wheels, but different electric vehicles may have fewer or more than four wheels. In addition, different types of electric vehicles 100 may incorporate the inventive concepts described herein, including motorcycles, airplanes, trucks, boats, train locomotives, and other types of vehicles. Certain parts generated using embodiments of the present invention may be used in the vehicle 100.

[0155] Figure 2A schematic diagram of an exemplary energy storage system 200 is shown, which shows various components. The energy storage system 200 generally includes a modular housing having at least one base 202 and four side walls 204 (only two are shown in the figure). The modular housing is generally electrically isolated from the battery cells 206 accommodated. This can be achieved by physical isolation, by an electrically insulating layer, by selecting an insulating material as a modular housing, any combination thereof, or by another method. The base 202 can be an electrically insulating layer on a metal sheet or a non-conductive / electrically insulating material such as polypropylene, polyurethane, polyvinyl chloride, another plastic, a non-conductive composite material, or insulating carbon fiber. The side wall 204 can also include an insulating layer or be formed of a non-conductive or electrically insulating material, such as polypropylene, polyurethane, polyvinyl chloride, another plastic, a non-conductive composite material, or insulating carbon fiber. One or more interconnect layers 230 can be located above the battery cells 206, and the top plate 210 is located above the interconnect layer 230. The top plate 210 can be a single plate or formed by multiple plates.

[0156] The individual battery cells 106 and 206 are typically lithium-ion battery cells having an electrolyte containing lithium ions and positive and negative electrodes. Figure 3 A schematic diagram of a lithium-ion battery cell 300 is shown. Lithium ions 350 are dispersed throughout electrolyte 320 within container 360. Container 360 can be part of the battery cell. Lithium ions 350 migrate between positive electrode 330 and negative electrode 340. Separator 370 separates the negative electrode from the positive electrode. Circuit 310 connects the negative electrode and the positive electrode.

[0157] The present invention provides new electrolytes and battery systems (such as those described above) for grid and electric vehicle applications, as well as newly discovered compounds and compositions for such systems. Certain embodiments described herein include a non-aqueous electrolyte for a lithium ion battery comprising at least one lithium salt, at least one non-aqueous solvent, and an additive component comprising at least one effective additive. The at least one effective additive is selected from:

[0158] (a) 3-aryl substituted 1,4,2-dioxazol-5-one compounds according to formula (I):

[0159]

[0160] wherein R is any aromatic substituent, any unsaturated aliphatic substituent or any aliphatic substituent containing one or more fluorine atoms; or

[0161] (b) 3-CRR'R" substituted 1,4,2-dioxazol-5-one compounds according to formula (II):

[0162]

[0163] wherein R, R' and R" are each hydrogen, an alkyl substituent or an aromatic substituent; or

[0164] (c) R-substituted nitrile sulfite compounds according to formula (III):

[0165]

[0166] wherein R is any alkyl or aromatic substituent.

[0167] Exemplary 3-aryl substituted 1,4,2-dioxazol-5-one compounds according to certain embodiments include those shown in Table 1.

[0168] Table 1 Summary of 3-aryl substituted 1,4,2-dioxazol-5-one compounds

[0169]

[0170]

[0171]

[0172] Chemical structures of other exemplary additives for the electrolyte solutions discussed herein include the formula shown above: 3-methyl-1,4,2-dioxazol-5-one (MDO) (Formula IV) and benzonitrile sulfite, 3-phenyl-1,3,2,4-dioxathiazole 2-oxide (BS) (Formula VI).

[0173] MDO or 3-methyl-1,4,2-dioxazol-5-one has been shown to passivate graphite anodes in the presence of propylene carbonate (PC) to prevent exfoliation. See, for example, Chem. Mater., 2017, 29(18), pp 7733–7739.

[0174] In certain further embodiments, the additive added to the electrolyte solution described herein is 0.01-6 wt %, based on the total weight of the electrolyte solution. In other embodiments, the at least one effective additive is 0.25-5 wt %, 0.35-4.5 wt %, 0.45-4 wt %, 0.55-3.5 wt %, 0.65-3 wt %, 0.75-2.5 wt %, 0.85-2 wt %, 0.95-2 wt %, 1.05-1.5 wt %, 1-5 wt %, 1-4 wt %, 1-3 wt %, 2-4 wt %, 1-2 wt %, 3-4 wt %, 2-5 wt % or 2-4 wt %. In other embodiments, the concentration of the at least one effective additive is about 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5% or 6% by weight.

[0175] The additive component may include a combination of the additives described herein. Additionally, the additive component may include ethylene sulfate, lithium difluorophosphate, vinylene carbonate, fluoroethylene carbonate, and combinations thereof.

[0176] In certain embodiments, the at least one non-aqueous solvent is a carbonate solvent. In further embodiments, the carbonate solvent is ethylene carbonate or dimethyl carbonate. In further embodiments, the non-aqueous solvent comprises at least 2 non-aqueous solvents.

[0177] In other embodiments, the battery system described herein has an initial capacity retention rate of 95% after 200 cycles between 3.0V and 4.3V at a charge rate of C / 3CCCV at 40°C. In further embodiments, the battery system has an initial capacity retention rate of 95% after 300 cycles between 3.0V and 4.3V at a charge rate of C / 3CCCV at 40°C. In further embodiments, the battery system has an initial capacity retention rate of 95% after 400 cycles between 3.0V and 4.3V at a charge rate of C / 3CCCV at 40°C.

[0178] MDO (Formula IV), 3-phenyl-1,4,2-dioxazol-5-one (PDO, Formula V) and BS (benzonitrile sulfite, or 3-phenyl-1,3,2,4-dioxathiazole 2-oxide, Formula VI) and their binary blends were investigated on LiNi 1–x–y Mn x Co y Cell formation, long-term cycling performance, and high-temperature storage behavior in O2(NMC) / graphite pouch cells. Results reported by others strongly suggest that MDO works primarily by passivating the graphite electrode. However, it is unclear whether these additives affect the cathode. Therefore, the research described in this paper also tested each additive in a binary additive mixture with VC, DTD, and LFO, which are known to sometimes produce beneficial effects at the cathode.

[0179] The differential capacitance results indicate that MDO and PDO form a passivating solid electrolyte interface layer on the graphite electrode during cell formation, whereas BS does not, demonstrating that PDO is a promising new additive, especially when used as a binary blend with lithium difluorophosphate or ethylene sulfate.

[0180] Pre-experimental setup

[0181] Although the battery system itself can be packaged in different ways according to the present disclosure, the experimental device generally uses a machine-made "sealed battery cell" to systematically evaluate the battery system using a general device, which includes a dual additive electrolyte system and materials used as positive and negative electrodes. Unless otherwise specified, all percentages mentioned in this application are weight percentages. Those skilled in the art will understand that the type of additive to be used and the concentration to be used will depend on the characteristics most desired to be improved and the other components and designs used in the lithium-ion battery to be manufactured, and can be obviously obtained from this application.

[0182] Additive synthesis

[0183] MDO, PDO and BS were synthesized using the routes shown below.

[0184]

[0185] Reaction a) shows the synthesis of 3-methyl-1,4,2-dioxazol-5-one (MDO), reaction b) shows the synthesis of 3-phenyl-1,4,2-dioxazol-5-one (PDO), and reaction c) shows the synthesis of benzonitrile sulfite (BS).

[0186] All solvents and starting materials were used as received without further purification. Thionyl chloride (1M in CH2Cl2) and benzohydroxamic acid (98%) were purchased from Alfa Aesar. 1,1'-Carbonyldiimidazole (CDI, ≥98%) and acetohydroxamic acid (95%) were purchased from Oakwood Chemical Inc. After preparation, the additives were characterized by nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR). Full details of the synthesis as well as the characterization results are provided below.

[0187] MDO and PDO were synthesized as follows. To a stirred solution of hydroxamic acid (5.00 g, 36.5 mmol, 1 eq.) in dichloromethane (120 mL), 1,1'-carbonyldiimidazole (5.92 g, 36.5 mmol, 1 eq.) was added in one portion. The mixture was stirred at room temperature for half an hour, quenched with 50 mL of 1N H2SO4, extracted with dichloromethane (3×40 mL), and dried over Na2SO4. The volatiles were removed under reduced pressure to give 3-substituted-1,4,2-dioxazol-5-ones. The product (3-methyl-1,4,2-dioxazol-5-one) was recrystallized from diethyl ether using liquid nitrogen, or from a 10:1 mixture of cyclohexane:acetone (3-phenyl-1,4,2-dioxazol-5-one). The structure of 3-methyl-1,4,2-dioxazol-5-one (MDO) is shown below:

[0188]

[0189] The structure of 3-phenyl-1,4,2-dioxazol-5-one (PDO) is shown below:

[0190]

[0191] Other 3-substituted-1,4,2-dioxazol-5-ones including o-FDO, m-FDO, p-FDO, p-MODO and TDO were also synthesized. These compounds were prepared by the following steps: Potassium carbonate (K2CO3, 3.32 g, 24.0 mmol, 2 equivalents) and hydroxylamine hydrochloride (HN2OH*HCl, 1.67 g, 24.0 mmol, 2 equivalents) were dissolved in 40 mL of water (H2O), to which 60 mL of ethyl acetate was added. 12.0 mmol of the corresponding acid chlorides (c-FDO: 2-fluorobenzoyl chloride; m-FDO: 3-fluorobenzoyl chloride; p-FDO, 4-fluorobenzoyl chloride; p-MODO: 4-methoxybenzoyl chloride; TDO: 2-thiophenecarboxylic acid chloride) were dissolved in 20 mL of ethyl acetate and added dropwise at 0 °C under constant stirring with a magnetic bar. The reaction was allowed to warm to room temperature and continued under stirring for 16 hours. The aqueous layer was extracted with ethyl acetate (3×30 mL), dried over anhydrous sodium sulfate (Na2SO4), and the solvent was removed under reduced pressure. The residue from the previous step was added to 40 mL of dichloromethane, and 1,1'-carbonyldiimidazole (1.95 g, 12.0 mmol, 1 equivalent) was added in one portion. The reaction was allowed to proceed for 30 minutes with constant stirring with a magnetic stirring bar. The reaction was then quenched with 1M H2SO4 (25 mL), extracted with dichloromethane (3×25 mL), and then dried over anhydrous sodium sulfate. The solvent was removed under reduced pressure to obtain the product.

[0192] Benzonitrile sulfite (BS, 5-phenyl-1,3,2,4-dioxathiazole 2-oxide) was prepared as follows. To a solution of thionyl chloride (30 mL, 1 M, 30 mmol, 3 equivalents), benzohydroxamic acid (1.4 g, 10.0 mmol, 1 equivalent) was added. The mixture was stirred at room temperature for 6 hours. Excess thionyl chloride and solvent were removed under reduced pressure to give 5-phenyl-1,3,2,4-dioxathiazole 2-oxide (1.57 g, 80%). The product was recrystallized from diethyl ether using liquid nitrogen for purification. The structure of 5-phenyl-1,3,2,4-dioxathiazole 2-oxide is shown below:

[0193]

[0194] Additive Characterization

[0195] After isolation and purification, the MDO, PDO and BS additives synthesized as described above were characterized by nuclear magnetic resonance spectroscopy (NMR) using a Bruker AV500 spectrometer controlled by ICON-NMR software. 1 H NMR (CDCl3, 500 MHz) characterizes MDO: 2.35 (s, 3H), such as Figure 4 As shown. Use 13C NMR (CDCl3, 125 MHz) characterized MDO: 164.0, 154.2, 10.5, such as Figure 5 As shown. Use 1 H NMR (CDCl3, 300MHz) characterization of PDO: 7.83-7.89 (m, 2H), 7.61-7.69 (m, 1H), 7.50-7.59 (m, 2H), such as Figure 7 As shown. Use 13 CNMR (CDCl3, 125MHz) characterizes PDO: 163.7, 154.0, 133.9, 129.6, 126.7, 120.3, such as Figure 8 As shown. Use 1 H NMR (CDCl3, 500MHz) characterization BS: 7.90-7.96 (m, 2H), 7.56-7.64 (m, 1H), 7.47-7.55 (m, 2H), such as Fig.10 As shown. Use 13 CNMR (CDCl3, 125MHz) characterization BS: 157.3, 133.1, 129.3, 128.2, 120.8, such as Fig.11 Chemical shifts are expressed in ppm relative to the residual solvent peak.

[0196] A 4 cm attenuated total reflection (ATR) instrument equipped with a germanium crystal was used, controlled by MicoLab PC software. -1 The materials were characterized by Fourier transform infrared spectroscopy (FTIR) using a Cary 630 FTIR (Agilent Technologies) with a resolution of 1000 nm. The FTIR spectrum of 3-methyl-1,4,2-dioxazol-5-one (MDO) is shown in Figure 6 ; The spectrum of 3-phenyl-1,4,2-dioxazol-5-one (PDO) is shown in Fig. 9 ; The spectrum of BS is shown in Fig.12 .

[0197] Lithium-ion battery cells

[0198] Dry (no electrolyte), vacuum-sealed LiNi with capacities of approximately 220 mAh and approximately 230 mAh, respectively 0.5 Mn 0.3 Co 0.2 O2(NMC532) / graphite and LiNi 0.6 Mn 0.2 Co 0.2O2 (NMC622) / graphite pouch cells were from LiFun Technology (Tianyuan District, Zhuzhou, Hunan, China). The cells were cut in an argon glove box under a heatseal, dried at 80 °C for 14 h under vacuum, and then returned to the glove box for filling. All solutions used 1.2 mol L -1 LiPF6 (BASF, ≥99.9%): a solvent mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) from BASF (<20 ppm H2O) in a mass ratio of 3:7. Additives MDO (synthesized as described above), PDO (synthesized as described above), BS (synthesized as described above), VC (BASF, ≥99.8%), DTD (Guangzhou Tianci Material Technology Co., Ltd., ≥98%) and LiPO2F2 (abbreviated as "LFO", Shenzhen Kaipu Chemical Technology Co., Ltd.) were added to the electrolyte solution individually or as a binary blend in the mass percentages shown. The battery cell was filled with 1.0±0.1 g of solution, sealed at 90 kPa gauge pressure using a compact vacuum sealer (MSK-115A, MTI Corp.), and immediately maintained at 1.5 V at room temperature (21-25°C) to avoid corrosion of the copper collector during the subsequent wetting period of about 24 hours. The cells were then loaded into a temperature-controlled chamber (40.0 ± 0.1 °C) and connected to a Maccor 4000 series automated testing system (Maccor Inc.). Since gas formation was expected to occur during the formation process, the pouch cells were clamped using soft rubber (at approximately 25 kPa gauge), which has been previously observed to significantly improve experimental precision.

[0199] Electrochemical testing

[0200] SEI formation was performed as follows: the cell was charged to 4.3V at C / 20, held at 4.3V for 1 h, discharged to 3.8V at C / 20, and then held at 3.8V for 1 h. Before and after formation, the cell was weighed underwater so that the change in displacement volume could be determined using the Archimedean principle. The cell was then degassed by cutting the bag open in an argon glove box and resealed using a compact vacuum sealer. The cell was weighed again and the electrochemical impedance spectroscopy (EIS) was measured at 10.0±0.1°C using a BioLogic VMP3 instrument (100kHz-10mHz, sine amplitude ±10mV). After formation, the cell was stored or cycled for a long time.

[0201] For storage, the cell was kept at 40 ± 0.1 °C while cycling between 2.8-4.3 V twice and then kept at 4.3 V for 24 h. The cell temperature was then increased to 60. ± 0.1 °C and the cell voltage was recorded at open circuit for 500 h. After storage, the cell was again cycled twice and then charged to 3.8 V. EIS was then measured and the cell was weighed again underwater to determine gas evolution during storage.

[0202] For long-term cycling, the cell was kept at 40.±0.1°C and cycled at C / 3 to 4.3V, holding the voltage at 4.3V until the charge current dropped below C / 20. The cell was then discharged at C / 3 to 2.8V and then charged again. Slow charge and discharge cycles at C / 20 were performed every 50 cycles.

[0203] Density functional theory calculations

[0204] Density functional theory (DFT) calculations were performed using Gaussian (G09.d01) as described in MJ Frisch, GW Trucks, HB Schlegel, GE Cuseria, MA Robb, JR Cheeseman, et al., Gaussian 09, Gaussian, Inc., Wallingford, CT, USA (2009). Geometry optimization and canonical mode analysis were performed using: the M062X hybrid function as described in Y. Zhao and D. G. Truhlar, Theor. Chem. Acc., 120, 215–241 (2007); the IEFPCM-UFF implicit solvent model (ε=20) as described in D. S. Hall, J. Self, and J. R. Dahn, J. Phys. Chem. C, 119, 22322–22330 (2015), J. Tomasi, B. Mennucci, and R. Cammi, Chem. Rev., 105, 2999–3094 (2005), and J. Tomasi, B. Mennucci, and E. Cancès, J. Mol. Struct. THEOCHEM, 464, 211–226 (1999); and the 6-311++G(2df,2pd) basis set. The B3LYP hybrid functional generally offers an excellent balance of speed and accuracy, while the M062X double hybrid functional generally provides higher accuracy for molecules with charge separation. The polarizable continuum model (PCM) was chosen to balance computational speed and accuracy. This choice comes with an inherent loss of accuracy because the implicit solvent model does not account for factors such as solvation sheath structure and preferential solvation in binary solvents. The standard electrode potentials are calculated from the following (1) oxidation and (2) reduction reactions of the molecule M:

[0205]

[0206]

[0207] Full details of the calculation of electrode half-potentials from DFT-calculated reaction free energies are known in the art, including the conversion from absolute potentials to relative electrode potentials.

[0208] Results and Discussion

[0209] During the initial stages of the first charging step, the potential of the positive electrode increases very slowly, while the potential of the negative electrode surface decreases relatively quickly. As a result, it is during this “formation” step that the negative electrode SEI is generated primarily by electrochemical reduction of EC and / or electrolyte additives on the graphite surface. Fig.13 The differential capacitance versus voltage (dQ / dV vs. V) plots for the first charging step are shown to consider whether the additives in this work directly generate the negative electrode SEI layer. For both cell types, the introduction of MDO into the cell resulted in a charge at about 2.1 V. 电池单元 The wide reduction feature starting at Fig.13 ). Considering that the cathode potential is initially about 3.5 ± 0.1 V vs Li / Li + Therefore, it is estimated that this reduction feature starts at about 1.4 V vs Li / Li + Note that this reduction feature is very small and is only seen from the cell containing 2% MDO (see inset). 电池单元 (about 0.9V vs Li / Li + ), the origin of which is unclear. However, using DFT calculations, the reduction potential of MDO was found to be closer to the second feature, E 0 还原,计算值 =0.67V vsLi / Li + (Table 2). Finally, due to the reduction of EC co-solvent, at 2.85 V 电池单元 There is a small feature here. Fig.13 A "control" cell was formed, which was prepared without any additives for comparison. For the 1% MDO cell, 2.85V 电池单元 The feature at has a larger area, indicating incomplete graphite passivation, whereas in the 2% MDO cell, the feature is small. This result supports the observations previously reported by others that MDO passivates graphite electrode surfaces.

[0210] The battery cell prepared with PDO has a differential capacitance diagram ( Fig.13 ) show two clear features. The first reduction feature is in the NMC622 / graphite cell (about 1.4V vs. Li / Li + ) at about 2.1V 电池单元 At NMC532 / graphite battery cells (about 1.5V vs Li / Li + ) starts at about 2.0V (see inset). The second feature is at about 1.15V vs Li / Li for both cell types ( + ) are both around 2.35V 电池单元Like MDO, the latter is closer to the DFT-calculated reduction potential, 1.18 V vs. Li / Li + (Table 2). The EC reduction feature is also weakly present in the PDO-containing cells, and its area is larger in the 1% PDO cell than in the 2% PDO cell. Moreover, the area of ​​the EC feature is very small for all PDO-containing cells compared to the cells without additive. This suggests that PDO leads to the formation of a passivating or at least partially passivating SEI on the graphite electrode.

[0211] Finally, the battery cell prepared with BS has a good performance in the differential capacitance diagram ( Fig.13 ). The areas of these features are directly proportional to the charge associated with the corresponding reduction and are significantly larger than those observed for MDO and PDO reductions. There is also a large difference in the onset potentials of these features, ranging from 2.2-2.4 V between the two cell types and the various additive blends. 电池单元 (about 1.1–1.3V vs Li / Li + ) and 2.4–2.6V 电池单元 (about 0.9–1.1Vvs Li / Li + ). For BS, both features are comparable to the DFT-calculated reduction potential of 1.16 V vs Li / Li + (Table 2). For cells prepared with BS as a standalone additive, the area of ​​the EC reduction feature did not decrease significantly. Therefore, the differential capacitance results indicate that BS reduction did occur, but without the formation of a passivating SEI on the graphite surface.

[0212] Table 2

[0213]

[0214] a Assumption E NMC,初始 About 3.5V vs.Li / Li +

[0215] The standard reduction potential and oxidation potential of the three additives are shown in Table 2. These potentials were calculated by DFT using M06-2X / 6-311++g(2df,2pd) / IEF-PCM (ε=20). Figure 3 The experimental reduction potentials were estimated for comparison.

[0216] exist Fig.14The amount of gas produced after a full formation cycle to 4.3 V is summarized in . While some gas production is unavoidable during the formation process, it is desirable to develop solution chemistries that do not produce excessive amounts of gas. It can be observed that the cell containing PDO produces the least amount of gas, while the cell containing MDO produces the most. Interestingly, the passivating behavior of MDO at the negative electrode as described above does not limit gas generation. Since the cell with the control electrolyte produces about 1.2 mL of gas during formation due to EC reduction, while the cell with 2% MDO produces about 2 mL of gas, it is clear that MDO must be present with Li + +e - The reaction produces gaseous products. Fig.14 DTD was shown to mitigate gas generation from MDO. Previous studies demonstrated that cells with 1% DTD or 2% DTD as the only additive (in NMC111 / graphite cells) produced 0.8 and 1.0 mL of gas during formation. Others have also demonstrated that in NMC532 / graphite cells containing only DTD, significant amounts of gas were also produced during formation, and that the gas was primarily ethylene. Therefore, it is believed that there is some synergy between MDO and DTD in their behavior that serves to limit gas generation.

[0217] After the formation and degassing regimen, the cells were divided into two groups and used for either high temperature storage or long-term cycling. For the former, the terminal voltage was automatically measured every 6 hours for 500 hours ( Fig.15 ). Some degree of self-discharge is inevitable under such harsh conditions, providing a practical opportunity to compare the performance of various battery cell chemistries over a relatively short period of time. Fig.15 It was shown that MDO, PDO and BS all showed poor storage performance when used as stand-alone additives. For these three additives, the introduction of DTD did not improve the performance, while LFO could bring some improvements for PDO and BS. During storage at high temperature and pressure, the generation of large amounts of gas often needs to be considered. Fig.14 showed that a large amount of gas evolution occurred in the battery cells prepared with MDO, while the cells containing PDO produced the least gas in this work. EIS measurements were also performed to observe whether there was a significant impedance growth during storage. However, the conclusions Fig.16 The results in show that impedance growth is not a significant issue for any of the cells tested in this work. Overall, the best storage performance was observed in cells containing VC as a co-additive, and the storage results indicate that PDO is the most promising of the three additives.

[0218] The remaining cells in this work were tested by long-term cycling at 40°C with a charge / discharge rate of C / 3 to 4.3 V. In the NMC622 / graphite cells, the MDO-containing cells performed worse than those made with 2% VC, a common additive that provides a good “standard” comparison ( Fig.17 ). This is consistent with S. This is in contrast to the results reported in A. Lerchen, L. Ibing, X. Cao, J. Kasnatscheew, F. Glorius, M. Winter, and R. Wagner, Chem. Mater., 29, 7733–7739 (2017), which found that 2% MDO outperformed 2% VC or 2% FEC. This difference may be attributed to the completely different electrolyte solutions used in that work, 1M LiPF6 in PC versus 1.2M LiPF6 in 25EC:5EMC:70DMC used in this study. The capacity retention of NMC622 / graphite cells prepared with 2% PDO (including binary blends) is comparable to or better than that of 2% VC cells. Among them, 2% PDO+1% DTD is the best performing mixture relative to 2% VC, which is in contrast to the poor storage behavior of this cell chemistry ( Fig.17 Finally, for the 2% BS + 2% VC blend, the cycling performance of BS in NMC622 / graphite cells ( Fig.17 ) is only comparable to the 2% VC cell. Of particular importance is the steep slope of ΔV versus cycle number (ΔV is the difference between the average charge voltage and the average discharge voltage) for the BS-containing cell ( Fig.17 ). This is usually a negative sign for the long-term performance of the battery cell. Therefore, these results support previous observations that PDO is the most promising of the three additives developed in this work.

[0219] For 1% MDO, 2% MDO+1% DTD, and 2% MDO+2% VC, the cycling of the MDO-containing cells is significantly better in the NMC532 / graphite cells, with comparable capacity retention to the 2% VC cells ( Fig.18 ). However, for all cells containing MDO, there is a considerable increase in ΔV versus cycle number. This indicates an increase in impedance and is often an early sign that the cell will eventually experience severe capacity fade and failure. The cells prepared with PDO as a standalone additive exhibited worse cycling performance than the 2% VC cells in terms of discharge capacity and ΔV ( Fig.18). However, the PDO-based blends all outperformed 2% VC in terms of capacity retention. There was also little increase in ΔV vs. cycle number for 2% PDO+1% DTD and 2% PDO+1% LFO, suggesting that they are both potentially good solution chemistries in NMC532 / graphite cells. Finally, all BS-containing cells were worse than 2% VC in this cell type.

[0220] Finally, it is considered whether the storage performance of the PDO-containing battery cell improves or degrades during multiple charge-storage cycles. Fig.19 It is shown that the Fig.15 b) Open circuit voltage of a PDO-containing cell that was then charged back to the upper voltage limit of 4.3V and stored for an additional 500 hours. The results show that the voltage drop is significantly smaller during the second storage period relative to the first storage period. This finding is significant because it shows that PDO performs well in storage, but requires a sufficiently long period of SEI growth and maturation. The long-term evolution of additive-derived SEI layers is a complex area of ​​research and additional research is needed to understand how to model this process to obtain accurate expectations of battery life and performance evolution.

[0221] Therefore, the cycling, gas evolution, and storage performances indicate that PDO is a promising new electrolyte additive, especially when used in combination with DTD and LFO co-additives.

[0222] in conclusion

[0223] This work characterizes the high temperature storage and long-term cycling performance of lithium-ion NMC / graphite pouch cells prepared with a recently developed electrolyte additive, MDO, and two new additives, PDO and BS. Differential capacitance versus capacitance indicates that both MDO and PDO form a passivating SEI layer on the graphite electrode surface during cell formation, whereas BS does not. The reduction signatures are generally consistent with DFT predictions, but the presence of multiple reduction peaks requires further investigation to rationalize them. Cells containing PDO as a single additive exhibit the best performance, but these performances are still superior to those of cells containing VC. Binary blends of these additives with VC, DTD, and LFO were also tested. Cells prepared with 2% PDO / 1% DTD and 2% PDO / 1% LFO additive blends outperformed those of cells containing VC in long-term cycling tests. However, the high temperature storage performance of 2% PDO / 1% LFO is superior to that of the 2% PDO / 1% DTD blend. Those skilled in the art will appreciate that the compositions described herein may be further optimized, for example, by adjusting the ratio of primary and secondary additives or by incorporating ternary blends.

[0224] The foregoing disclosure is not intended to limit the invention to the precise form disclosed or to the specific field of use. Therefore, it is contemplated that various alternative embodiments and / or modifications of the present disclosure are possible, regardless of whether explicitly described or implied herein, based on the disclosure. Therefore, having described the embodiments of the present disclosure, it will be appreciated by those of ordinary skill in the art that changes may be made in form and detail without departing from the scope of the present disclosure. Therefore, the present disclosure is limited only by the claims. Unless otherwise stated in the specification, references to additives in the specification generally refer to effective additives.

[0225] In the foregoing description, the present disclosure has been described with reference to specific embodiments. However, as will be understood by those skilled in the art, the various embodiments disclosed herein may be modified or otherwise implemented in various other ways without departing from the spirit and scope of the present disclosure. Therefore, this description should be considered exemplary, and the purpose is to teach those skilled in the art how to make and use the various embodiments of the disclosed battery system. It should be understood that the form of the disclosure shown and described herein will be considered as a representative embodiment. Equivalent elements or materials may replace those represented and described herein. In addition, certain features of the present disclosure may be used in a manner independent of the use of other features, all of which will be apparent to those skilled in the art who benefit from the description of the present invention. Expressions such as "including", "comprising", "incorporating", "containing", "having", and "being" used to describe and claim the present disclosure are intended to be interpreted in a non-exclusive manner, i.e., allowing for the presence of items, components or elements that are not explicitly described. References to the singular should also be interpreted as referring to the plural. References to "about" or "approximately" should be understood to refer to ±10%. Similarly, references to any percentage of additives are interpreted to refer to ±10%.

[0226] In addition, each embodiment disclosed herein should be understood in an exemplary and explanatory sense and should never be interpreted as a limitation of the present disclosure. All connection references (e.g., attached, fixed, coupled, connected, etc.) are only used to help the reader understand the present invention and do not constitute limitations, especially limitations on the position, orientation, or use of the systems and / or methods disclosed herein. Therefore, if there are connection references, they should be interpreted broadly. Moreover, such connection references do not necessarily infer that two elements are directly connected to each other.

[0227] In addition, all numerical terms, such as but not limited to "first", "second", "third", "primary", "secondary", "main" or any other general and / or numerical terms, should be regarded merely as identifiers to assist the reader in understanding the various elements, embodiments, variations and / or modifications of the present invention, and shall not constitute any limitations, especially the order or priority of any element, embodiment, variation and / or modification relative to or compared to another element, embodiment, variation and / or modification.

[0228] It should also be understood that one or more of the elements depicted in the figures may also be implemented in a more separate or integrated manner, or even removed or rendered inoperable in some cases.

Claims

1. A non-aqueous electrolyte for an energy storage device, comprising a lithium salt, a non-aqueous solvent and an additive component, wherein the additive component comprises a 3-CRR'R" substituted 1,4,2-dioxazol-5-one compound according to formula (II): wherein R is an alkyl substituent or an aromatic substituent; and wherein R' and R" are each independently hydrogen, an alkyl substituent or an aromatic substituent; and The additive component further comprises a compound selected from the group consisting of ethylene sulfate, lithium difluorophosphate, vinylene carbonate, fluoroethylene carbonate, and combinations thereof.

2. The non-aqueous electrolyte according to claim 1, wherein the concentration of the 3-CRR'R" substituted 1,4,2-dioxazol-5-one compound is 0.01-6 wt % based on the total weight of the non-aqueous electrolyte.

3. The non-aqueous electrolyte of claim 1, wherein the concentration of the 3-CRR'R" substituted 1,4,2-dioxazol-5-one compound is about 2 wt% based on the total weight of the non-aqueous electrolyte.

4. The nonaqueous electrolyte according to claim 1, wherein at least one of R, R' and R" is an aromatic substituent. The nonaqueous electrolyte according to claim 1 , wherein the nonaqueous solvent comprises a carbonate solvent.

6. The non-aqueous electrolyte according to claim 5, wherein The carbonate solvent is selected from ethylene carbonate, dimethyl carbonate and a combination thereof. The non-aqueous electrolyte according to claim 5 , further comprising a second non-aqueous solvent.

8. An energy storage device, comprising: negative electrode; positive electrode; and A non-aqueous electrolyte comprising a lithium salt, a non-aqueous solvent and an additive component comprising lithium difluorophosphate and a 3-CRR'R" substituted 1,4,2-dioxazol-5-one compound according to formula (II): wherein R, R' and R" are each independently hydrogen, an alkyl substituent or an aromatic substituent.

9. The energy storage device of claim 8, wherein at least one of R, R' and R" is an aromatic substituent.

10. The energy storage device of claim 8, wherein the concentration of the 3-CRR'R" substituted 1,4,2-dioxazol-5-one compound is 0.01-6 wt% based on the total weight of the non-aqueous electrolyte.

11. The energy storage device of claim 8, wherein the concentration of the 3-CRR'R" substituted 1,4,2-dioxazol-5-one compound is 2 wt% based on the total weight of the non-aqueous electrolyte.

12. The energy storage device of claim 8, wherein the additive component further comprises ethylene sulfate.

13. The energy storage device of claim 8, wherein the additive component further comprises a compound selected from the group consisting of vinylene carbonate, fluoroethylene carbonate, and combinations thereof.

14. The energy storage device of claim 8, wherein the non-aqueous solvent comprises a carbonate solvent.

15. The energy storage device of claim 14, wherein the carbonate solvent is selected from the group consisting of ethylene carbonate, dimethyl carbonate, and combinations thereof.

16. The energy storage device of claim 8, further comprising a second non-aqueous solvent.

17. The energy storage device according to claim 8, wherein: The energy storage device contained 95% initial capacity retention after 200 cycles at 40° C. with a charge rate of C / 3 CCCV between 3.0 V and 4.3 V.

18. The energy storage device according to claim 8, wherein: The energy storage device contained 95% initial capacity retention after 400 cycles at 40° C. with a charge rate of C / 3 CCCV between 3.0 V and 4.3 V.

19. An electric vehicle comprising: Drive motor; Gearbox; Electronic equipment; and An energy storage device comprising a negative electrode, a positive electrode and a non-aqueous electrolyte, wherein the non-aqueous electrolyte comprises a lithium salt, a non-aqueous solvent and an additive component, wherein the additive component comprises a 3-CRR'R" substituted 1,4,2-dioxazol-5-one compound according to formula (II): wherein R, R' and R" are each independently hydrogen, an alkyl substituent or an aromatic substituent; and The energy storage device has an initial capacity retention of 95% after 200 cycles at 40° C. at a charge rate of C / 3 CCCV between 3.0 V and 4.3 V. 20 . The electric vehicle according to claim 19 , wherein the concentration of the 3-CRR′R″ substituted 1,4,2-dioxazol-5-one compound is 0.01 to 6 wt % based on the total weight of the non-aqueous electrolyte.

21. The electric vehicle according to claim 19, wherein the concentration of the 3-CRR'R" substituted 1,4,2-dioxazol-5-one compound is 2 wt% based on the total weight of the non-aqueous electrolyte.

22. The electric vehicle of claim 19, wherein at least one of R, R' and R" is an aromatic substituent.

23. The electric vehicle of claim 19, wherein the additive component further comprises ethylene sulfate.

24. The electric vehicle of claim 19, wherein the additive component further comprises lithium difluorophosphate.

25. The electric vehicle of claim 19, the additive component further comprising a compound selected from the group consisting of vinylene carbonate, fluoroethylene carbonate, and combinations thereof.

26. The electric vehicle of claim 19, wherein the non-aqueous solvent comprises a carbonate solvent.

27. The electric vehicle of claim 26, wherein the carbonate solvent is selected from the group consisting of ethylene carbonate, dimethyl carbonate, and combinations thereof.

28. The electric vehicle of claim 19, further comprising a second non-aqueous solvent.

29. The electric vehicle according to claim 19, wherein: The energy storage device contained 95% initial capacity retention after 400 cycles at 40° C. with a charge rate of C / 3 CCCV between 3.0 V and 4.3 V.

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