Electrolyte, lithium-ion battery and electrical device

Abstract

Provided is an electrolyte for a lithium-ion battery. The electrolyte includes a lithium salt, a solvent, a first additive having a structure of Formula I, and a second additive being anhydride, where is C3-C6 cycloalkane or C3-C6 cycloalkene, R1 is selected from a group comprising -H, -C1-4 alkyl, -C1-4 fluoroalkyl, -C2-4 alkenyl, and -C2-4 fluoroalkenyl, R2 is selected from a group comprising -C1-4 alkyl, -C1-4 fluoroalkyl, -C2-6 alkenyl and -C2-6 fluoroalkeny, and n is 0 or 1, and in which at least one of, R1, and R2 contains one or more unsaturated bond.

Description

[0001] P139474-19679

[0002] ELECTROLYTE, LITHIUM-ION BATTERY AND ELECTRICAL DEVICE

[0003] FIELD

[0004] The present disclosure relates to the technical field of lithium-ion battery, and more particularly to an electrolyte, a lithium-ion battery and an electrical device.

[0005] BACKGROUND

[0006] A lithium-ion battery is widely used in electronics, electric vehicles, distributed energy storage, and other fields due to its advantages of high energy density, high output power, long cycling life, and low environmental pollution. Electrolyte, as the “blood” of the lithium-ion battery, has a significant impact on the performance of the lithium-ion battery through its interaction with positive and negative electrodes. In recent years, the global climate has been changing. The requirements for the lithium-ion battery are becoming increasingly stringent. When exposed to high-temperature conditions, the electrolyte decomposes under the catalysis of Lewis acids such as phosphorus pentafluoride and the side reactions of the electrolyte accelerate, increasing gas production, thereby decreasing the service life of the lithium-ion battery reversible capacity of the lithium-ion battery.

[0007] The additive combination in the related art forms a passivation film on the active material with higher internal resistance and increasing thickness with cycling, which significantly compromises the safety and performance of the lithium-ion battery during cycling and storage under high-temperature conditions.

[0008] SUMMARY

[0009] Embodiments of the present disclosure seek to solve at least one of the problems existing in the related art to at least some extent.

[0010] In view of the above, the present disclosure provides in embodiments an electrolyte, a lithium-ion battery and an electrical device.

[0011] In a first aspect, there is provided in embodiments an electrolyte for a lithium-ion battery, including: a lithium salt, a solvent, a first additive having a structure of Formula I second additive being anhydride, where is C3-C6 cycloalkane or C3-C6 cycloalkene, Ri is selected from a group comprising -H, -C1-4 alkyl, -C1-4 fluoroalkyl, -C2-4 alkenyl, and -C2-4 fluoroalkenyl, R2 is selected from a group comprising -C1-4 alkyl, -C1-4 fluoroalkyl, -C2-6 alkenyl and -C2-6 fluoroalkeny, and n is 0 or 1, and in which at least one of O, Rband R2 contains one or more unsaturated bond. P139474-19679

[0012] According to the embodiments of the present disclosure, the first additive contained in the electrolyte, which has a sulfonic ester group, forms lithium alkyl sulfonate on the anode active material of the lithium-ion battery during a formation process, contributing to the formation of a sulfur-rich interface fdm with high ionic conductivity. In addition, the first additive contains the ring structure and the unsaturated bond, allowing it to preferentially undergo ring-opening polymerization and / or addition polymerization on the surface of the electrode active material of the lithium-ion battery, compared to the solvent (such as Ethylene Carbonate (EC)). This process forms a high- temperature resistant interface film that isolates the electrode active material from the electrolyte, inhibits side reactions, and reduces the consumption of the electrolyte and active lithium ions.

[0013] In some embodiments of the present disclosure, O contains one or more unsaturated bond.

[0014] According to the embodiments of the present disclosure, the unsaturated bond on O may be easy to induce the ring -opening reaction of the O?and the first additive may perform the ring -opening polymerization or the addition polymerization on a position of ring-opened O , which further improves a polymerization efficiency, and thus accelerates the formation of the interface fdm.

[0015] In some embodiments of the present disclosure, Ri contains one or more unsaturated bond, and / or R2 contains one or more unsaturated bond.

[0016] According to the embodiments of the present disclosure, the first additive with such structure may have more polymerization sites for performing the ring-opening polymerization and the addition polymerization, thus further accelerating the polymerization efficiency. The interface fdm formed on the electrode surfaces is faster and denser, which may better protect the electrodes, inhibit side reactions, and reduce the consumption of the electrolyte and active lithium ions.

[0017] In some embodiments of the present disclosure, O is selected from a group including substituted with

[0018] Rl at 1’ end.

[0019] In some embodiments of the present disclosure, Ri is -H or isopropenyl, and R2 is 1 -propenyl, ethyl, or isopropyl.

[0020] In some embodiments of the present disclosure, the first additive is selected from a group comprising Formulas la to II, P139474-19679

[0021] In some embodiments of the present disclosure, the second additive has a structure of Formula II, where R3, together with the carbon atoms to which it is attached, form cyclopropyl, partially- or fully- fluorinated cyclopropyl, cyclobutyl, partially- or fully- fluorinated cyclobutyl, cyclohexyl, partially- or fully- fluorinated cyclohexyl, methylcyclohexyl, phenyl, partially- or fully- fluorinated phenyl, methylphenyl, partially- or fully- fluorinated methylphenyl, cyclohexeny, pyridyl, imidazolyl, thiophenyl, or furanyl.

[0022] According to the embodiments of the present disclosure, the second additive is preferentially oxidized compared to the solvent and other additives, such as vinylene carbonate, 1,3 -propane sultone, enhancing the protection of the positive electrode interface, thereby suppressing intragranular cracks. In addition, the second additive contained in the electrolyte is beneficial in regulating thermal runaway reactions because the anhydride may participate in polymerization reactions by capturing active free radicals.

[0023] According to the embodiments of the present disclosure, the synergistic action of first and second additives leads to the formation of thin, dense SEI films with enhanced inorganic / organic complementary components, improving the dynamic performance, cycling performance and high-temperature storage performance of the lithium-ion battery.

[0024] In some embodiments of the present disclosure, the second additive is selected from a group comprising Formulas Ila to Ilh, P139474-19679

[0025] In some embodiments of the present disclosure, the electrolyte includes the first additive at an amount of 0.2% to 5% and the second additive at an amount of 0.1% to 2.5%, based on a total mass of the electrolyte. For example, the electrolyte includes the first additive at an amount of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or 4.5% based on a total mass of the electrolyte. For example, the electrolyte includes the second additive at an amount of 0.2%, 0.4%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2% or 2.4% based on a total mass of the electrolyte.

[0026] According to the embodiments of the present disclosure, the synergistic effect of the first and the second additive, which meets the condition of containing the first additive at an amount of 0.2% to 5% and the second additive at an amount of 0.1% to 2.5% based on a total mass of the electrolyte, may be further effective.

[0027] In some embodiments of the present disclosure, the electrolyte includes the first additive at an amount of 0.3% to 1% and the second additive at an amount of 0.1% to 0.8%, based on a total mass of the electrolyte. For example, the electrolyte includes the first additive at an amount of 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, or 0.9% based on a total mass of the electrolyte. For example, the electrolyte includes the second additive at an amount of 0.2%, 0.3%, 0.4%, 0.5%, or 0.6% based on a total mass of the electrolyte.

[0028] According to the embodiments of the present disclosure, the synergistic effect of the first and the second additive, which meets the condition of containing the first additive at an amount of 0.3% to 1% and the second additive at an amount of 0.1% to 0.8% based on a total mass of the electrolyte, may be further effective.

[0029] In some embodiments of the present disclosure, the lithium salt is selected from a group including lithium hexafluorophosphate, lithium bisfhiorosulfonimide, lithium bistrifluoromethanesulfonimidate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium tetrafluoro(oxalate)phosphate, lithium bis(oxalate)borate, lithium difluoro(oxalate)borate, lithium trioxalate phosphate, and lithium difluorodioxalate phosphate.

[0030] In some embodiments of the present disclosure, the electrolyte includes the lithium salt at an amount of 5% to 20% based on a total mass of the electrolyte. For example, the electrolyte includes the lithium salt at an amount of 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, or 19% based on a total mass of the electrolyte.

[0031] In some embodiments of the present disclosure, the electrolyte includes the lithium salt at an amount of 10% P139474-19679 to 16% based on a total mass of the electrolyte. For example, the electrolyte includes the lithium salt at an amount of 11%, 12%, 13%, 14%, or 15% based on a total mass of the electrolyte.

[0032] In some embodiments of the present disclosure, the solvent is selected from a group including a C3-6 carbonate compound, a C3-8 carboxylate compound, a sulfone compound, and an ether compound.

[0033] In some embodiments of the present disclosure, the electrolyte comprises the solvent at an amount of 70% to 92% based on a total mass of the electrolyte. For example, the electrolyte comprises the solvent at an amount of 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, or 91% based on a total mass of the electrolyte.

[0034] In some embodiments of the present disclosure, the electrolyte includes a third additive selected from vinylene carbonate, 1,3 -propane sultone, fluoroethylene carbonate, tris (trimethylsilyl) phosphate, tris (trimethylsilyl) borate, ethylene sulfate, methylene methanedisulfonate, lithium difluorophosphate, ethoxy(pentafluoro)cyclotriphosphazene, and butanedinitrile.

[0035] In some embodiments of the present disclosure, the electrolyte includes the third additive at an amount of 0.2% to 5% based on a total mass of the electrolyte. For example, the electrolyte includes the third additive at an amount of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or 4.5% based on a total mass of the electrolyte.

[0036] In a second aspect, there is provided in embodiments a lithium-ion battery including the electrolyte according to any one of the embodiments of the present disclosure.

[0037] According to the embodiments of the present disclosure, the lithium-ion battery including the first additive and the second additive. The first additive contained in the electrolyte, which has a sulfonic ester group, forms lithium alkyl sulfonate on the anode active material of the lithium-ion battery during a formation process, contributing to the formation of a sulfur-rich interface film with high ionic conductivity. In addition, the first additive contains the ring structure and the unsaturated bond, allowing it to preferentially undergo ring-opening polymerization and / or addition polymerization on the surface of the electrode active material of the lithium-ion battery, compared to the solvent (such as Ethylene Carbonate (EC)). This process forms a high-temperature resistant interface film that isolates the electrode active material from the electrolyte, inhibits side reactions, and reduces the consumption of the electrolyte and active lithium ions. The second additive is preferentially oxidized compared to the solvent and other additives, such as vinylene carbonate, 1,3 -propane sultone, enhancing the protection of the positive electrode interface, thereby suppress intragranular cracks. In addition, the second additive contained in the electrolyte is beneficial in regulating thermal runaway reactions because the anhydride may participate in polymerization reactions by capturing active free radicals. The synergistic action of first and second additives leads to the formation of thin, dense SEI films with enhanced inorganic / organic complementary components, improving the dynamic performance, cycling performance and high -temperature storage performance P139474-19679 of the lithium-ion battery.

[0038] In a third aspect, there is provided in embodiments an electrical device including the lithium-ion battery any one of the embodiments of the present disclosure.

[0039] According to the embodiments of the present disclosure, the electrical device has advantages of long service life, excellent usage performance and improved high-temperature resistance.

[0040] It is to be understood that both the foregoing general description and the following detailed description are illustrative and explanatory only and shall not be construed to limit the present disclosure.

[0041] BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to clearly illustrate technical solutions of embodiments of the disclosure, a description of drawings used in the embodiments is given below.

[0043] FIG. 1 is a gas chromatogram (GC) spectrum of a first additive prepared according to an embodiment of the present disclosure.

[0044] FIG. 2 is a GC spectrum of a first additive prepared according to another embodiment of the present disclosure.

[0045] DETAILED DESCRIPTION

[0046] Reference will now be made in detail to embodiments. The implementations set forth in the following description of the embodiments do not represent all implementations consistent with the present disclosure.

[0047] Terms used herein in embodiments of the present disclosure are only for the purpose of describing specific embodiments, but should not be construed to limit the present disclosure. As used in the embodiments of the present disclosure and the appended claims, “a / an”, and “the” in singular forms are intended to include plural forms, unless clearly indicated in the context otherwise. It should also be understood that, the term “and / or” used herein represents and contains any or all possible combinations of one or more associated listed items.

[0048] When term “about” is used, this term may mean that there can be a variance in value of up to ±10%, of up to 5%, of up to 2%, of up to 1%, of up to 0.5%, of up to 0.1%, or up to 0.01%.

[0049] Term “range” disclosed in the present disclosure is defined in the form of a lower limit and an upper limit, a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The range defined in this way can be inclusive or exclusive, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is understood that ranges of 60-110 and 80- 120 are also obtained. In addition, if the listed minimum values are 1 and 2, and if the listed maximum values are P139474-19679

[0050] 3, 4 and 5, the ranges of 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 may be obtained. In the present disclosure, unless otherwise specified, the numerical range “a-b” means the abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range “0-5” means that all the real numbers between “0-5” have been listed, and “0-5” is only the abbreviated representation of these numerical combinations. In addition, when a parameter is an integer >2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0051] Electrolyte for lithium-ion battery

[0052] The embodiments of the present disclosure provides an electrolyte for a lithium-ion battery. The electrolyte includes a first additive (an unsaturated sulfonic ester compound) and a second additive (anhydride). Compared with the lithium-ion battery including electrolyte with the additive in the related arts, the lithium-ion battery, including the electrolyte provided in the embodiments of the present disclosure, has an improved cycling performance and an improved high-temperature resistance.

[0053] In the embodiments of the present disclosure, the electrolyte includes a lithium salt, a solvent, a first additive having a structure of Formula I second additive being anhydride.

[0054] The first additive is a sulfonic ester compound (i.e, a sulfonate compound).

[0055] According to the embodiments of the present disclosure, it can be seen from the formula that the sulfonic ester compound contains a sulfonic ester group (-SO2O-) with two S=O and one S-O.

[0056] In the Formula I, O is C3-C6 cycloalkane or C3-C6 cycloalkene, in which the C3-C6 cycloalkane is a cycloalkane group containing 3-6 carbon atoms, such as propane, butane, pentane, and hexane, and the C3-C6 cycloalkene is a cycloalkene group containing 3-6 carbon atoms, such as cyclopropene, cyclobutene, cyclopentene, and cyclohexene. According to the embodiments of the present disclosure, the C3-C6 cycloalkane and the C3-C6 cycloalkene both contain a ring structure, so that Omay perform a ring-opening reaction.

[0057] In the Formula I, Ri is selected from a group comprising -H, -C1-4 alkyl, -C1-4 fluoroalkyl, -C2-4 alkenyl, and -C2-4 fluoroalkenyl. According to the embodiments of the present disclosure, the -C1-4 alkyl is an alkyl with 1-4 carbon atoms, having a saturated chemical bond structure, for example, methyl (-CH3), ethyl (-C2H5), propyl (including n-propyl and isopropyl) and butyl (including n-butyl, isobutyl and tert-butyl). The -C2-4 alkenyl is an alkenyl with 2-4 carbon atoms, having at least one carbon-carbon double bond, for example, vinyl, propenyl, and butenyl. The -C1-4 fluoroalkyl is an alkyl with 1-4 carbon atoms, on which the hydrogen atom is partially or fully replaced by the fluorine atom, and the -C1-4 fluoroalkyl has a saturated chemical bond structure. The -C2-4 P139474-19679 fluoroalkenyl is an alkenyl with 2-4 carbon atoms, on which the hydrogen atom is partially or fully replaced by the fluorine atom, and the -C2-4 fluoroalkenyl has at least one carbon -carbon double bond.

[0058] In the Formula I, R2 is selected from a group comprising -C1-4 alkyl, -C1-4 fluoroalkyl, -C2-6 alkenyl and -C2- 6 fluoroalkeny. According to the embodiments of the present disclosure, the C2-6 alkenyl is an alkenyl with 2-6 carbon atoms, and the C2-6 fluoroalkeny is an alkenyl with 2-6 carbon atoms, on which the hydrogen atom is partially or fully replaced by the fluorine atom.

[0059] In the Formula I, the “n” in the Formula I is 0 or 1.

[0060] In the Formula I, at least one of O, Rband R2 contains one or more unsaturated bond.

[0061] According to the embodiments of the present disclosure, the first additive contained in the electrolyte, which has a sulfonic ester group, forms lithium alkyl sulfonate on the anode active material of the lithium-ion battery during a formation process, contributing to the formation of a sulfur-rich interface film with high ionic conductivity. In addition, the first additive contains the ring structure and the unsaturated bond, allowing it to preferentially undergo ring-opening polymerization and / or addition polymerization on the surface of the electrode active material of the lithium-ion battery, compared to the solvent (such as Ethylene Carbonate (EC)). This process forms a high- temperature resistant interface film that isolates the electrode active material from the electrolyte, inhibits side reactions, and reduces the consumption of the electrolyte and active lithium ions.

[0062] In some embodiments of the present disclosure, O contains one or more unsaturated bond. According to the embodiments of the present disclosure, the unsaturated bond on O may be easy to induce the ring-opening reaction of the O , and the first additive may perform the ring-opening polymerization or the addition polymerization on a position of ring -opened O, which further improves a polymerization efficiency, and thus accelerates the formation of the interface film.

[0063] In some embodiments of the present disclosure, Ri contains one or more unsaturated bond, and / or R2 contains one or more unsaturated bond. According to the embodiments of the present disclosure, the first additive with such structure may have more polymerization sites for performing the ring-opening polymerization and the addition polymerization, thus further accelerating the polymerization efficiency. The interface film formed on the electrode surfaces is faster and denser, which may better protect the electrodes, inhibit side reactions, and reduce the consumption of the electrolyte and active lithium ions. For example, as shown in the Formula la below, O includes one unsaturated bond, and R2 includes one unsaturated bond. For another example, as shown in the Formula Ic below, O includes one unsaturated bond, Ri includes one unsaturated bond and R2 includes one unsaturated bond.

[0064] In some embodiments of the present disclosure, O is selected from a group including P139474-19679

[0065] RI at 1’ end.

[0066] In some embodiments of the present disclosure, Ri is -H or isopropenyl, and R2 is 1 -propenyl, ethyl, or isopropyl.

[0067] In some embodiments of the present disclosure, the first additive is selected from a group comprising

[0068] Formulas la to II,

[0069] As shown in the Formula la to II, the first additive in the embodiments of the present disclosure contains the ring structure and at least one unsaturated bond.

[0070] For example, in the Formula la, O of the first additive is cyclohexene, which has the ring structure and one unsaturated bond, Ri is hydrogen atom, R2 is propenyl, and the “n” is 1. In the Formula la, O and R2 include the unsaturated bond. The first additive having the Formula la may perform the ring -opening polymerization and the addition polymerization synchronously on the surface of electrode active material of the lithium-ion battery, to form the interface films on the electrode surfaces. The interface film may isolate the contact between the electrode surface and the electrolyte, inhibit side reactions, and reduce the consumption of the electrolyte and active lithium

[0071] 10ns.

[0072] In another example, in the Formula If is cyclopentene, Ri is hydrogen atom, R2 is isopropyl, and the “n” P139474-19679 is 1. In the Formula If, only O include the unsaturated bond. The first additive having the Formula If may perform the ring-opening polymerization on the electrode surfaces of the lithium-ion battery, and also may perform the addition polymerization after the ring-opening reaction, such that the interface films on the electrode surfaces may be formed to protect the electrodes.

[0073] In some embodiments of the present disclosure, the second additive has a structure of Formula II, where R3, together with the carbon atoms to which it is attached, form cyclopropyl, partially- or fully- fluorinated cyclopropyl, cyclobutyl, partially- or fully- fluorinated cyclobutyl, cyclohexyl, partially- or fully- fluorinated cyclohexyl, methylcyclohexyl, phenyl, partially- or fully- fluorinated phenyl, methylphenyl, partially- or fully- fluorinated methylphenyl, cyclohexeny, pyridyl, imidazolyl, thiophenyl, or furanyl.

[0074] According to the embodiments of the present disclosure, the second additive is preferentially oxidized compared to the solvent and other additives, such as vinylene carbonate, 1,3 -propane sultone, enhancing the protection of the positive electrode interface, thereby suppress intragranular cracks. In addition, the second additive contained in the electrolyte is beneficial in regulating thermal runaway reactions because the anhydride may participate in polymerization reactions by capturing active free radicals.

[0075] According to the embodiments of the present disclosure, the synergistic action of first and second additives leads to the formation of thin, dense SEI films with enhanced inorganic / organic complementary components, improving the dynamic performance, cycling performance and high-temperature storage performance of the lithium-ion battery.

[0076] In some embodiments of the present disclosure, the second additive is selected from a group comprising

[0077] Formulas Ila to Ilh,

[0078] In some embodiments of the present disclosure, the electrolyte includes the first additive at an amount of 0.2% to 5% and the second additive at an amount of 0.1% to 2.5%, based on a total mass of the electrolyte. For example, P139474-19679 the electrolyte includes the first additive at an amount of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or 4.5% based on a total mass of the electrolyte. For example, the electrolyte includes the second additive at an amount of 0.2%, 0.4%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2% or 2.4% based on a total mass of the electrolyte.

[0079] According to the embodiments of the present disclosure, the synergistic effect of the first and the second additive, which meets the condition of containing the first additive at an amount of 0.2% to 5% and the second additive at an amount of 0.1% to 2.5% based on a total mass of the electrolyte, may be further effective.

[0080] In some embodiments of the present disclosure, the electrolyte includes the first additive at an amount of 0.3% to 1% and the second additive at an amount of 0.1% to 0.8%, based on a total mass of the electrolyte. For example, the electrolyte includes the first additive at an amount of 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, or 0.9% based on a total mass of the electrolyte. For example, the electrolyte includes the second additive at an amount of 0.2%, 0.3%, 0.4%, 0.5%, or 0.6% based on a total mass of the electrolyte.

[0081] According to the embodiments of the present disclosure, the synergistic effect of the first and the second additive, which meets the condition of containing the first additive at an amount of 0.3% to 1% and the second additive at an amount of 0.1% to 0.8% based on a total mass of the electrolyte, may be further effective.

[0082] In some embodiments of the present disclosure, the lithium salt is selected from a group including lithium hexafluorophosphate, lithium bisfluorosulfonimide, lithium bistrifluoromethanesulfonimidate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium tetrafluoro(oxalate)phosphate, lithium bis(oxalate)borate, lithium difluoro(oxalate)borate, lithium trioxalate phosphate, and lithium difluorodioxalate phosphate.

[0083] In some embodiments of the present disclosure, the electrolyte includes the lithium salt at an amount of 5% to 20% based on a total mass of the electrolyte. For example, the electrolyte includes the lithium salt at an amount of 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, or 19% based on a total mass of the electrolyte.

[0084] In some embodiments of the present disclosure, the electrolyte includes the lithium salt at an amount of 10% to 16% based on a total mass of the electrolyte. For example, the electrolyte includes the lithium salt at an amount of 11%, 12%, 13%, 14%, or 15% based on a total mass of the electrolyte.

[0085] In some embodiments of the present disclosure, the solvent is selected from a group including a C3-6 carbonate compound, a C3-8 carboxylate compound, a sulfone compound, and an ether compound.

[0086] In some embodiments of the present disclosure, the electrolyte comprises the solvent at an amount of 70% to 92% based on a total mass of the electrolyte. For example, the electrolyte comprises the solvent at an amount of 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, or 91% based on a total mass of the electrolyte. P139474-19679

[0087] In some embodiments of the present disclosure, the electrolyte includes a third additive selected from vinylene carbonate, 1,3 -propane sultone, fluoroethylene carbonate, tris (trimethylsilyl) phosphate, tris (trimethylsilyl) borate, ethylene sulfate, methylene methanedisulfonate, lithium difluorophosphate, ethoxy(pentafluoro)cyclotriphosphazene, and butanedinitrile.

[0088] In some embodiments of the present disclosure, the electrolyte includes the third additive at an amount of 0.2% to 5% based on a total mass of the electrolyte. For example, the electrolyte includes the third additive at an amount of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or 4.5% based on a total mass of the electrolyte.

[0089] Lithium-ion battery

[0090] The embodiments of the present disclosure provides a lithium-ion battery. The lithium-ion battery includes the electrolyte according to any embodiment of the present disclosure. The lithium-ion battery of the embodiments of the present disclosure has an excellent stability of the surface of electrode material, a low battery impedance, a low consumption of electrolyte and a low consumption of active lithium ion, an improved cycling performance and an improved high-temperature resistance.

[0091] [Positive electrode plate]

[0092] The positive electrode plate includes a positive electrode current collector and a positive electrode fdm layer disposed on at least one surface of the positive electrode current collector. The positive electrode film layer includes the cathode active material.

[0093] As an example, the positive electrode current collector has two surfaces along a thickness direction thereof and facing in opposite directions, and the positive electrode fdm layer is provided on either or both of the two surfaces.

[0094] The positive electrode fdm layer includes the cathode active material. The cathode active material may be selected from materials capable of absorbing and releasing lithium.

[0095] The specific kind of the cathode active material is not particularly limited and may be selected according to requirements. As an example, the cathode active material may include, but is not limited to, lithium iron phosphate (LiFePCL), lithium manganese phosphate (LiMnPCL), lithium cobalt phosphate (LiCoPCh), iron pyrophosphate (Li2FeP2C>7), lithium cobaltate (LiCoCh), spinel-type lithium manganate (LiM^CL), spinel-type lithium nickel manganate (LiNio.5Mn1.5O4), layered lithium manganate (LiMnO2), lithium nickelate (LiNiO2), lithium niobate (LiNbO2), lithium ferrite (LiFeO2), lithium magnesium oxide (LiMgO2), lithium calcium oxide (LiCaO2), lithium cuprate (LiCuO2), lithium zincate (LiZnO2), lithium molybdate (LiMoO2), lithium tantalate (LiTaO2), lithium tungstate (LiW02), lithium nickel cobalt aluminum oxide (LiNixCoyAli-x-yO2, 0<x<l, 0<y<l, 0 <x + y<l, e.g. LiNi0.8Co0.15Al0.05O2), lithium nickel cobalt manganese oxides (LiNixCoyMni-x-yO2, 0<x<l, 0<y<l, 0<x+y<l, e.g., P139474-19679

[0096] LiNii / sCoi / sMni / sCh, LiNio.5Coo.2Mno.3O2, LiNio.6Coo.2Mno.2O2, LiNio.8Coo.1Mno.1O2, etc.), lithium-rich materials (e.g. lithium-rich nickel cobalt manganese oxides), manganese oxides (Mn02), vanadium oxides, sulfur oxides, silicate oxides, and at least one of its respective modified compounds. These materials may be used separately or in combination (for example two or more kinds of materials are used).

[0097] The above cathode active material may be modified, for example is doped, coated, or both doped and coated with a modification compound.

[0098] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil may be used. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metallic material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a substrate of a high molecular material such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0099] In some embodiments, the positive electrode film layer optionally includes a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene- tetrafhioroethylene terpolymer, tetrafluoroethylene-hexafhioropropylene copolymer, and a fluorine-containing acrylate resin.

[0100] In some embodiments, the positive electrode fdm layer optionally includes a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0101] In some embodiments, the positive electrode plate may be prepared by: dispersing the above-mentioned components for preparing the positive electrode plate, such as the cathode active material, the conductive agent, the binder and any other components in a solvent (such as N-methyl pyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and obtaining the positive electrode plate after drying, cold pressing and other processes.

[0102] [Negative electrode plate]

[0103] The negative electrode plate includes a negative electrode current collector and a negative electrode fdm layer disposed on at least one surface of the negative electrode current collector. The negative electrode fdm layer includes an anode active material.

[0104] As an example, the negative electrode current collector has two surfaces along a thickness direction thereof and facing in opposite directions, and the negative electrode film layer is provided on either or both of the two P139474-19679 surfaces.

[0105] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, a copper foil may be used. The composite current collector may include a polymeric material substrate and a metal layer formed on at least one surface of the polymeric material substrate. The composite current collector may be formed by forming a metallic material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a substrate of a high molecular material such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0106] In some embodiments, the anode active material may be an anode active material known in the art. As an example, the anode active material may include at least one selected from artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials and lithium titanate. The silicon-based material may be at least one selected from elemental silicon, silicon-oxygen compounds, silicon-carbon complexes, siliconnitrogen complexes, and silicon alloys. The tin-based material may be at least one selected from elemental tin, tin oxide compounds, and tin alloys. The present disclosure is not limited to these materials, and other materials that may be used as an anode active material for a battery may be used. These anode active materials may be used separately or in combination (for example two or more kinds of materials are used).

[0107] In some embodiments, the negative electrode film layer optionally includes a binder. The binder may be at least one selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

[0108] In some embodiments, the negative electrode film layer optionally includes a conductive agent. The conductive agent may be at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0109] In some embodiments, the negative electrode film layer optionally includes other adjuvants, such as thickeners (e.g. sodium carboxymethylcellulose (CMC-Na)).

[0110] In some embodiments, the negative electrode plate may be prepared by: dispersing the above-mentioned components for preparing the negative electrode plate, such as the anode active material, the conductive agent, the binder and any other components in a solvent (such as deionized water) to form a negative electrode slurry; coating the negative electrode slurry on the negative electrode current collector, and obtaining the negative electrode plate after drying, cold pressing and other processes.

[0111] In some embodiments, the lithium-ion battery further includes a separator. The separator may be a porous membrane with good chemical stability and mechanical stability, which is not limited in the present disclosure. P139474-19679

[0112] In some embodiments, the material of the separator is selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multilayer composite film, materials of individual layers may be the same or different.

[0113] In some embodiments, the lithium-ion battery includes an outer package. The outer package is used to package the electrodes and the electrolyte.

[0114] In some embodiments, the outer package of the lithium-ion battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell and the like. Alternatively, the outer package of the lithium-ion battery may be a soft package, such as a soft bag. The soft bag may be made of a polymer material such as plastics, polypropylene, polybutylene terephthalate and polybutylene succinate.

[0115] The shape of the lithium-ion battery may be cylindrical, square or any other shape, which is not limited in the present disclosure.

[0116] Experimental Section

[0117] The following Examples are included to demonstrate certain aspects and embodiments of the present disclosure. It should be appreciated by those of skill in the art, however, that the following description is illustrative only and should not be taken in any way as a restriction of the present disclosure.

[0118] Method for synthesizing the first additive having Formula la

[0119] 2.803g (0.025mol) of 3 -cyclohexene- 1 -methanol was weighed and added in a lOOmL reaction flask, then 3.033g (0.03mol) of trimethylamine was added into the reaction flask. The reaction flask containing the 3- cyclohexene-1 -methanol and the trimethylamine was placed in an ice water bath at 0°C for 10 minutes. 4.217g (0.03mol) of 2-propene-l -sulfonyl chloride was weighed and dissolved in 15mL of anhydrous dichloromethane. The dichloromethane solution containing 2-propene-l -sulfonyl chloride was gradually added to the reaction flask above. The reaction flask was placed at 0°C for 30 minutes. Then the reaction flask was gradually heated to 25°C and then performs the reaction for 6h. After filtration, the filtrate was collected, and cooled to 0°C. 0.739 g (0.01 mol) of Li2CC>3 and 20pL (650 ppm) deionized water were added in the filtrate, the mixed solution is stirred for 40 min, and heated to 25°C and then performs the reaction for 4h. Then, excessive deionized water was added to wash and extract the organic phase. Anhydrous MgSCU was added into the organic phase to dry for 12 h. After P139474-19679 filtration and vacuum drying, 3.257g yellow liquid (with a yield of 60.3 %) was obtained. The GC purity of the product was 97.6 %, and the GC-MS molecular weight of the product was 216 (the molecular weight theoretical value of the compound having formula la is 216.1).

[0120] Method for synthesizing the first additive having Formula lb

[0121] 2.803g (0.025mol) of 3 -cyclohexene- 1 -methanol was weighed and added in a lOOmL reaction flask, then 3.033g (0.03mol) of trimethylamine was added into the reaction flask. The reaction flask containing the 3- cyclohexene-1 -methanol and the trimethylamine was placed in an ice water bath at 0°C for 10 minutes. 3.534g (0.0275mol) of ethylsulfonyl chloride was weighed and dissolved in 15mL of anhydrous dichloromethane. The dichloromethane solution containing ethylsulfonyl chloride was gradually added to the reaction flask above within 30 minutes. The reaction flask was placed at 0°C for 30 minutes. Then the reaction flask was gradually heated to 30°C and then performs the reaction for 6h. After filtration, the filtrate was collected and cooled to 0°C. 0.09 g (0.0037 mol) of LiOH and 20pL (800 ppm) deionized water were added in the filtrate, the mixed solution is stirred for 30 min, and heated to 25°C and then performs the reaction for 8h. Then, excessive deionized water was added to wash and extract the organic phase. Anhydrous MgSCfi was added into the organic phase to dry for 12 h. After filtration and vacuum drying, 3.250g yellow liquid (with a yield of 63.6 %) was obtained.

[0122] Method for synthesizing the first additive having Formula Ic

[0123] 3.805g of perillyl alcohol was weighed and added in a reaction flask, then 3.033g of triethylamine was added into the reaction flask. The reaction flask containing the perillyl alcohol and the triethylamine was placed in an ice water bath at 0°C for 10 minutes. 4.217g of 2-propenyl-l -sulfonyl chloride was weighed and dissolved in 15mL of anhydrous dichloromethane. The dichloromethane solution containing 2-propenyl-l -sulfonyl chloride was gradually added to the reaction flask above. The reaction flask was placed at 0°C for 30 minutes. Then the reaction flask was gradually heated to 30°C to obtain the first additive having the Formula Ic. The purification steps of this method are essentially the same as those in the methods for synthesizing Formula la, lb, Id, If, Ih, and li, so they will not be elaborated upon here.

[0124] Method for synthesizing the first additive having Formula Id P139474-19679

[0125] 2.502g (0.025mol) of cyclopentane methanol was weighed and added in a lOOmL reaction flask, then 3.033g (0.03mol) of triethylamine was added into the reaction flask. The reaction flask containing the cyclopentane methanol and the triethylamine was placed in an ice water bath at 0°C for 10 minutes. 4.217g (0.03mol) of 2- propenyl-1 -sulfonyl chloride was weighed and dissolved in 15mL of anhydrous dichloromethane. The dichloromethane solution containing 2-propenyl-l -sulfonyl chloride was gradually added to the reaction flask above within 30 minutes. The reaction flask was placed at 0°C for 30 minutes. Then the reaction flask was gradually heated to 25 °C and then performs the reaction for 6h. After filtration, the filtrate was collected and cooled to 0°C. 0.739g (O.Olmol) of U2CO3 and 20pL (658ppm) deionized water were added in the filtrate, the mixed solution is stirred for 40 min, and heated to 25 °C and then performs the reaction for 4h. Then, excessive deionized water was added to wash and extract the organic phase. Anhydrous MgSCL was added into the organic phase to dry for 12 h. After filtration and vacuum drying, 3.319g yellow liquid (with a yield of 65.0%) was obtained.

[0126] Method for synthesizing the first additive having Formula le

[0127] 2.452g (0.025mol) of 3 -cyclopentene- 1 -methanol was weighed and added in a lOOmL reaction flask, then 3.033g (0.03mol) of triethylamine was added into the reaction flask. The reaction flask containing the 3- cyclopentene-1 -methanol and the triethylamine was placed in an ice water bath at 0°C for 10 minutes. 4.217g of 2-propenyl-l -sulfonyl chloride was weighed and dissolved in 15mL of anhydrous dichloromethane. The dichloromethane solution containing 2-propenyl-l -sulfonyl chloride was gradually added to the reaction flask above. The reaction flask was placed at 0°C for 30 minutes. Then the reaction flask was gradually heated to 25°C to obtain the first additive having the Formula le. The purification steps of this method are essentially the same as those in the methods for synthesizing Formula la, lb, Id, If, Ih, and li, so they will not be elaborated upon here.

[0128] Method for synthesizing the first additive having Formula If

[0129] 2.452g (0.025mol) of 3 -cyclopentene- 1 -methanol was weighed and added in a 100mL reaction flask, then 3.033g (0.03mol) of triethylamine was added into the reaction flask. The reaction flask containing the 3- cyclopentene-1 -methanol and the triethylamine was placed in an ice water bath at 0°C for 10 minutes. 4.260g (0.03mol) of isopropylsulfonyl chloride was weighed and dissolved in 15mL of anhydrous dichloromethane. The P139474-19679 dichloromethane solution containing isopropylsulfonyl chloride was gradually added to the reaction flask above within 30 minutes. The reaction flask was placed at 0°C for 30 minutes. Then the reaction flask was gradually heated to 25 °C and then performs the reaction for 6h. After filtration, the filtrate was collected and cooled to 0°C. 0.739g (O.Olmol) of U2CO3 and 20pL (657ppm) deionized water were added in the filtrate, the mixed solution is stirred for 40 min, and heated to 25 °C and then performs the reaction for 4h. Then, excessive deionized water was added to wash and extract the organic phase. Anhydrous MgSCfi was added into the organic phase to dry for 12 h. After filtration and vacuum drying, 3.129g yellow liquid (with a yield of 61.3%) was obtained. The GC purity of the product was 97.6%, and the GC-MS molecular weight of the product was 204 (the molecular weight theoretical value of the compound having formula If is 204.3).

[0130] Method for synthesizing the first additive having Formula Ig

[0131] 2.803g of 3 -cyclohexene- 1 -methanol was weighed and added in a reaction flask, then 3.033g of triethylamine was added into the reaction flask. The reaction flask containing the 3 -cyclohexene- 1 -methanol and the triethylamine was placed in an ice water bath at 0°C for 10 minutes. 4.260g of isopropylsulfonyl chloride was weighed and dissolved in 15mL of anhydrous dichloromethane. The dichloromethane solution containing isopropylsulfonyl chloride was gradually added to the reaction flask above. The reaction flask was placed at 0°C for 30 minutes. Then the reaction flask was gradually heated to 30°C to obtain the first additive having the Formula Ig. The purification steps of this method are essentially the same as those in the methods for synthesizing Formula la, lb, Id, If, Ih, and li, so they will not be elaborated upon here.

[0132] Method for synthesizing the first additive having Formula Ih

[0133] 3.805g (0.025mol) of perilla alcohol was weighed and added in a lOOmL reaction flask, then 3.033g (0.03mol) of triethylamine was added into the reaction flask. The reaction flask containing the perilla alcohol and the triethylamine was placed in an ice water bath at 0°C for 10 minutes. 3.534g (0.0275mol)of ethylsulfonyl chloride was weighed and dissolved in 15mL of anhydrous dichloromethane. The dichloromethane solution containing ethylsulfonyl chloride was gradually added to the reaction flask above within 30 minutes. The reaction flask was placed at 0°C for 30 minutes. Then the reaction flask was gradually heated to 30°C and then performs the reaction for 8h. After filtration, the filtrate was collected and cooled to 0°C. 0.09g (0.0037mol) of LiOH and 20pL (659ppm) deionized water were added in the filtrate, the mixed solution is stirred for 30 min, and heated to 25 °C and then performs the reaction for 8h. Then, excessive deionized water was added to wash and extract the organic phase. Anhydrous MgSCfi was added into the organic phase to dry for 12 h. After filtration and vacuum drying, 3.554g yellow liquid (with a yield of 58.2%) was obtained. The GC purity of the product was 94.8%, and the GC-MS P139474-19679 molecular weight of the product was 244 (the molecular weight theoretical value of the compound having formula

[0134] Ih is 244.3).

[0135] Method for synthesizing the first additive having Formula li

[0136] 2.452g (0.025mol) of 2-cyclohexen-l-ol was weighed and added in a lOOmL reaction flask, then 3.033g (0.03mol) of trimethylamine was added into the reaction flask. The reaction flask containing the 2-cyclohexen-l- ol and the trimethylamine was placed in an ice water bath at 0°C for 10 minutes. 3.534g (0.0275mol) of ethylsulfonyl chloride was weighed and dissolved in 15mL of anhydrous dichloromethane. The dichloromethane solution containing ethylsulfonyl chloride was gradually added to the reaction flask above within 30 minutes. The reaction flask was placed at 0°C for 30 minutes. Then the reaction flask was gradually heated to 30°C and then performs the reaction for 8h. After filtration, the filtrate was collected and cooled to 0°C. 0.09g (0.0037mol) of LiOH and 20pL (690ppm) deionized water were added in the filtrate, the mixed solution is stirred for 30 min, and heated to 25 °C and then performs the reaction for 8h. Then, excessive deionized water was added to wash and extract the organic phase. Anhydrous MgSCfi was added into the organic phase to dry for 12 h. After filtration and vacuum drying, 2.826g yellow liquid (with a yield of 59.5%) was obtained. The GC purity of the product was 97.8%, and the GC-MS molecular weight of the product was 190 (the molecular weight theoretical value of the compound having formula li is 190.1).

[0137] The method for synthesizing Formula Ij, Ik, and II are essentially the same as the methods for synthesizing Formula la-Ii, so they will not be elaborated upon here.

[0138] Method for preparing electrolyte

[0139] Under an argon atmosphere (vaporous water <10 ppm), Ethylene Carbonate (EC), Diethyl Carbonate (DEC), and Ethyl Methyl Carbonate (EMC), were mixed to obtain a solvent at a weight ratio of 3:2:5. The first additive and the second additive were added in the solvent successively. Then the lithium salt (for example, LiPF(, and LiFSI) and the third additive were added to obtain the electrolyte (stored in a -10°C refrigerator).

[0140] Method for preparing lithium-ion battery

[0141] (i) Positive electrode plate is preparing by: dispersing polyvinylidene difluoride (PVDF) in the N-Methylpyrrolidone (NMP), adding conductive agent P139474-19679

[0142] (Super P), and adding LiNio.8Coo.1Mno.1O2 to obtain a positive electrode slurry (LiNio.8Coo.1Mno.1O2 : PVDF : Super P=97.4: 1.3: 1.3); coating the positive electrode slurry on a positive electrode current collector, and obtaining the positive electrode plate for lamination process after drying, rolling and slitting.

[0143] (ii) Negative electrode plate is preparing by: mixing synthetic graphite, conductive agent (Super P), silicon oxide powder, carboxymethyl cellulose sodium, styrene butadiene rubber with a mass ratio of 80.9:2.9:13.2:1.2:1.8; stirring at 250 rpm for 140 min to obtain a negative electrode slurry; dispersing the negative electrode slurry in the deionized water; coating a dispersed negative electrode slurry on the negative electrode current collector after sieving; obtaining the negative electrode plate for lamination process after drying, rolling and slitting.

[0144] (Hi) Battery cell is preparing by: laminating a silt positive electrode plate and a silt negative electrode plate with a separator consists of three layers made of PP, PE, and PP, respectively on a laminating machine.

[0145] (iv) Injection, Formation and Aging

[0146] After drying the battery cell at high temperature, the electrolytes provided in IE 1 to 17 and CE 1 to 8 are injected, respectively. After initial packaging, the obtained lithium-ion batteries are placed at room temperature for one day. Next, they are charged with a constant current of 0.05C for 2 hours, followed by charging at a constant current of 0.1C until the voltage reaches 3.85V.

[0147] Aging is performed at 50°C for one day, after which the lithium-ion battery is cooled to room temperature for final sealing.

[0148] Test methods

[0149] 1. Tests for prepared first additive

[0150] Material tests were performed on the first additive obtained from the methods for synthesizing the first additive. As examples, the first additive having Formula lb and the first additive having Formula Id, which were obtained from the above method, were tested by a gas chromatography-mass spectrometry (GC-MS) analyzer.

[0151] As shown in FIG. 1, the GC spectrum for the first additive having Formula lb shows a strongest peak at retention time of 10.372 min, with a peak area of 5320.02 and a peak area ratio of 98.5083% based on a total peak area of 5400.58. That is, the first additive having Formula lb obtained according to the method embodiment of the present disclosure has a GC purity of about 98.5%. In addition, the first additive having Formula lb obtained has a GC MS molecular weight of about 204, which conforms to the chemical formula of the first additive. A detailed P139474-19679 analysis of the spectrum in FIG. 1 is shown in the following table. Table 1 Analysis of FIG. 1

[0152] As shown in FIG. 2, the GC spectrum for the first additive having Formula Id shows a strongest peak at retention time of 9.602 min, with a peak area of 1845.01 and a peak area ratio of 98.1669% based on a total peak area of 1897.47. That is, the first additive having Formula Id obtained according to the method embodiment of the present disclosure has a GC purity of about 98.2%. In addition, the first additive having Formula Id obtained has a GC MS molecular weight of about 204, which conforms to the chemical formula of the first additive. A detailed analysis of the spectrum in FIG. 2 is shown in the following table.

[0153] Table 2 Analysis of FIG. 2

[0154] 2. Tests for performances of lithium-ion battery P139474-19679

[0155] A LiNio.8Coo.1Mno.1O2 / synthetic graphite soft package lithium-ion battery (e.g. 4.25 V) was used for tests of cycling, and storage, and tested by the Xinwei charge-discharge testing system.

[0156] 2.1 Cycling performance test at 25°C

[0157] At 25 °C, the lithium-ion batteries obtained in inventive examples and comparative examples were charged to 4.25 V by 1C constant current and constant voltage. After standing for 5 minutes, the lithium-ion batteries were discharged to 2.5 V by 1C constant current. The above was one charge / discharge cycle. The lithium-ion batteries were cycled for 350 cycles at 25 °C according to the above conditions. DCR values Ro of the lithium-ion batteries after 350 cycles were recorded according to the following DCR testing method.

[0158] Capacity retention rate (%) of the lithium-ion battery after 350 cycles = (discharge capacity of the 350th cycle / discharge capacity of the first cycle) x 100%.

[0159] 2.2 High temperature cycling performance test at 45°C

[0160] At 45 °C, the lithium-ion batteries obtained in inventive examples and comparative examples were charged to 4.25 V by 1C constant current and constant voltage. After standing for 5 minutes, the lithium-ion batteries were discharged to 2.5 V by 1C constant current. The above was one charge / discharge cycle, the lithium-ion batteries were cycled for 300 cycles at 45 °C according to the above conditions.

[0161] Capacity retention rate (%) of the lithium-ion battery after 300 cycles = (discharge capacity of the 300th cycle / discharge capacity of the first cycle) x 100%.

[0162] 3. High temperature storage test at 60°C

[0163] The lithium-ion batteries obtained in inventive examples and comparative examples were performed one charge-discharge cycle by a charge / discharge rate of 1C / 1C at 25°C. Then the lithium-ion batteries were charged to 4.25 V by 1C constant current and constant voltage, and a discharge capacity Qo was recorded. The fully charged batteries were stored at 60°C for 56 days, then the batteries were discharged by 1C constant current at 25 °C, and a discharge capacity Qawas recorded. Then the batteries were charged / discharged by the charge / discharge rate of 1C / 1C at 25 °C, and a discharge capacity Qb was recorded. DCR values Rb of the lithium-ion batteries after 60 days of storage were recorded according to the following DCR testing method. Residual capacity retention rates and recovery capacity retention rates, for the high temperature storage, of the batteries after 60 days of storage were calculated according to the following formula: residual capacity retention rate = Qa / Qox100 %; capacity recovery retention rate = Qb / Qox100 %. P139474-19679

[0164] 4. DCR testing

[0165] The lithium-ion batteries obtained in inventive examples and comparative examples were placed in a thermostat at 25°C for 5 minutes, then were charged to 4.25 V by 1C constant current and constant voltage. The batteries were discharged to 50% SOC by a discharge rate of 1C after standing for 30 minutes. Corresponding Voltage values Ui were recorded after standing for 60 minutes. Finally, the batteries were discharged for 30 seconds by a discharge rate of 4C, and corresponding voltage values U2 were recorded. DCR values R and DCR increase rates were calculated according to the following formula:

[0166] R=(Ui-U2) / (l4c);

[0167] DCR increase rate = (Rb-Ro) / Rox100%.

[0168] It should be noted that the present disclosure only describes some test method and conditions. Materials, measurements and processes that are known in the art are not described herein.

[0169] Examples

[0170] Inventive Example 1 (IE1)

[0171] The electrolyte for IE1 was prepared according to the corresponding method above. The electrolyte includes a solvent, LiPFe at an amount of 12.5%, the first additive (Formula la) at an amount of 0.5%, the second additive (Formula Ilf) at amount of 0.2%, VC at an amount of 0.5%, and FEC at an amount of 5%, based on a total mass of the electrolyte. Additionally, the solvent contains EC, DEC and EMC with a weight ratio of 3:2:5.

[0172] Inventive Example 2 (IE2)

[0173] The electrolyte for IE2 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE1 expect that the first additive is Formula lb.

[0174] Inventive Example 3 (IE3)

[0175] The electrolyte for IE3 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE1 expect that the first additive is Formula Ic.

[0176] Inventive Example 4 (IE4)

[0177] The electrolyte for IE4 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE1 expect that the first additive is Formula Id.

[0178] Inventive Example 5 (IE5)

[0179] The electrolyte for IE5 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE1 expect that the first additive is Formula le.

[0180] Inventive Example 6 (IE6) P139474-19679

[0181] The electrolyte for IE6 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE1 expect that the first additive is Formula If.

[0182] Inventive Example 7 (IE7)

[0183] The electrolyte for IE7 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE1 expect that the first additive is Formula Ig.

[0184] Inventive Example 8 (IE8)

[0185] The electrolyte for IE8 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE1 expect that the first additive is Formula Ih.

[0186] Inventive Example 9 (IE9)

[0187] The electrolyte for IE9 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE1 expect that the first additive is Formula lb and the second additive is Formula Ila.

[0188] Inventive Example 10 (IE 10)

[0189] The electrolyte for IE10 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE1 expect that the first additive is Formula lb and the second additive is Formula lib.

[0190] Inventive Example 11 (IE11)

[0191] The electrolyte for IE 11 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE1 expect that the first additive is Formula lb and the second additive is Formula lie.

[0192] Inventive Example 12 (IE 12)

[0193] The electrolyte for IE12 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE1 expect that the first additive is Formula lb and the second additive is Formula lid.

[0194] Inventive Example 13 (IE 13)

[0195] The electrolyte for IE13 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE1 expect that the first additive is Formula lb and the second additive is Formula lie.

[0196] Inventive Example 14 (IE 14)

[0197] The electrolyte for IE14 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE1 expect that the first additive is Formula lb and the second additive is Formula Ilg. P139474-19679

[0198] Inventive Example 15 (IE 15)

[0199] The electrolyte for IE15 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE1 expect that the first additive is Formula lb and the second additive is Formula Ilh.

[0200] Inventive Example 16 (IE 16)

[0201] The electrolyte for IE16 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE2 expect that the electrolyte contains the first additive at an amount of 0.3% and the second additive at an amount of 0.1%, based on a total mass of the electrolyte.

[0202] Inventive Example 17 (IE 17)

[0203] The electrolyte for IE17 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE2 expect that the electrolyte contains the first additive at an amount of 1% and the second additive at an amount of 0.8%, based on a total mass of the electrolyte.

[0204] Comparative Example 1 (CE1)

[0205] The electrolyte for CE1 was prepared in the same way as IE1 expect that the electrolyte does not contain the first and second additives.

[0206] Comparative Example 2 (CE2)

[0207] The electrolyte for CE2 was prepared in the same way as IE1 expect that the electrolyte does not contain the first additive.

[0208] Comparative Example 3 (CE3)

[0209] The electrolyte for CE3 was prepared in the same way as IE2 expect that the electrolyte does not contain the second additive.

[0210] Comparative Example 4 (CE4)

[0211] The electrolyte for CE4 was prepared in the same way as IE2 expect that the electrolyte contains the first additive at an amount of 5% based on a total mass of the electrolyte.

[0212] Comparative Example 5 (CE5)

[0213] The electrolyte for CE5 was prepared in the same way as IE2 expect that the electrolyte contains the second additive at an amount of 2% based on a total mass of the electrolyte.

[0214] Comparative Example 6 (CE6)

[0215] The electrolyte for CE6 was prepared in the same way as IE2 expect that the electrolyte contains the first additive at an amount of 0.1% and the second additive at an amount of 0.05%, based on a total mass of the electrolyte. P139474-19679

[0216] Comparative Example 7 (CE7)

[0217] The electrolyte for CE7 was prepared in the same way as IE2 expect replacing the first additive with bis(trimethylsilyl)sulfate.

[0218] Comparative Example 8 (CE8)

[0219] The electrolyte for CE8 was prepared in the same way as IE2 expect replacing the second additive with 2- methylmaleic anhydride. P139474-19679

[0220] Table 2 Results of cycling performance test P139474-19679

[0221] As we can see from the results of IE1 to IE 17, benefiting from the electrolyte containing both the first additive and the second additive, the lithium-ion batteries have an excellent cycling performance at room temperature (25 °C) and high temperature (45 °C).

[0222] By comparing the results of IE1 and CE1-3, it is apparent that the lithium-ion battery has an excellent cycling performance at room temperature (25 °C) and high temperature (45 °C) because of the addition of both the first P139474-19679 additive and the second additive. By comparing the results of IE2 and CE7, it is clear that compared to sultones (such as bis(trimethylsilyl)sulfate), the addition of the first additive having a structure of Formula I (such as Formula lb) significantly improves the cycling performance at room temperature (25°C) and high temperature (45°C) of the lithium-ion battery. By comparing the results of IE2 and CE8, it is clear that compared to other anhydride (such as 2-methylmaleic anhydride), the addition of the second additive having a structure of Formula II (such as Formula Ilf) significantly improves the cycling performance at room temperature (25 °C) and high temperature (45 °C) of the lithium-ion battery.

[0223] It can also be noted that the amounts of the first additive and the second additive in the electrolyte have preferred ranges, respectively, not that the higher the amount of the first additive or the second additive, the better the cycling performance. Excessive or insufficient amount of the first additive or the second additive may have adverse effects on the cycling performance. As we can see from the results of IE1-17 and CE 4-6, the lithium-ion batteries exhibit the better cycling performance, where the amount of the first additive ranges from 0.3 to 1% and the amount of the second additive ranges from 0.1 to 0.8%.

[0224] Table 3 Results of storage test P139474-19679

[0225] As we can see from the results of IE1 to IE 17, benefiting from the electrolyte containing both the first additive and the second additive, the lithium-ion batteries have an excellent high-temperature storage performance.

[0226] By comparing the results of IE1 and CE1-3, it is apparent that the lithium-ion battery has an excellent high- temperature storage performance because of the addition of both the first additive and the second additive. By comparing the results of IE2 and CE7, it is clear that compared to sultones (such as bis(trimethylsilyl)sulfate), the addition of the first additive having a structure of Formula I (such as Formula lb) significantly improves the high- temperature storage performance of the lithium-ion battery. By comparing the results of IE2 and CE8, it is clear that compared to other anhydride (such as 2-methylmaleic anhydride), the addition of the second additive having a structure of Formula II (such as Formula Ilf) significantly improves the high-temperature storage performance of the lithium-ion battery.

[0227] It can also be noted that the amounts of the first additive and the second additive in the electrolyte have preferred ranges, respectively. Excessive or insufficient amount of first additive may have adverse effects on the high-temperature storage performance. As we can see from the results of IE1-17 and CE 4-6, the lithium-ion batteries exhibit better high-temperature storage performance, where the amount of the first additive ranges from 0.3 to 1% and the amount of the second additive ranges from 0.1% to 0.8%.

[0228] Reference throughout this specification to “an embodiment,” “some embodiments,” “one embodiment”, “another example,” “an example,” “a specific example,” or “some examples,” means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. Thus, the appearances of the phrases such as “in some embodiments,” “in one embodiment”, “in an embodiment”, “in another example,” “in an example,” “in a specific example,” or “in some examples,” in various places throughout this specification are not necessarily referring to the same embodiment or example of the present disclosure. Furthermore, the particular features, structures, P139474-19679 materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0229] Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed here. This application is intended to cover any variations, uses, or adaptations of the disclosure following the general principles thereof and including such departures from the present disclosure as come within known or customary practice in the art. It is intended that the specification and examples be considered as illustrative only, with a true scope and spirit of the disclosure being indicated by the following claims.

Claims

P139474-19679CLAIMS1. An electrolyte for a lithium-ion battery, comprising: a lithium salt, a solvent, a first additive having a structure of Formula Ia second additive being anhydride, wherein O is C3-C6 cycloalkane or C3-C6 cycloalkene, Ri is selected from a group comprising -H, -C1-4 alkyl, -C1-4 fluoroalkyl, -C2-4 alkenyl, and -C2-4 fluoroalkenyl, R2 is selected from a group comprising -C1-4 alkyl, -C1-4 fluoroalkyl, -C2-6 alkenyl and -C2-6 fluoroalkeny, and n is 0 or 1, and wherein at least one of O, Ri, and R2 contains one or more unsaturated bond.

2. The electrolyte according to claim 1, wherein k contains one or more unsaturated bond.

3. The electrolyte according to claim 2, wherein Ri contains one or more unsaturated bond, and / or R2 contains one or more unsaturated bond.

4. The electrolyte according to claim 1, wherein J isselected from a group comprisingwherein kJ issubstituted with RI at 1’ end.

5. The electrolyte according to claim 4, wherein Ri is -H or isopropenyl, and R2 is 1 -propenyl, ethyl, or isopropyl.

6. The electrolyte according to claim 4, wherein the first additive is selected from a group comprisingP139474-196797. The electrolyte according to any one of claims 1 to 6, wherein the second additive has a structure of FormulaII,wherein R3, together with the carbon atoms to which it is attached, form cyclopropyl, partially- or fully- fluorinated cyclopropyl, cyclobutyl, partially- or fully- fluorinated cyclobutyl, cyclohexyl, partially- or fully- fluorinated cyclohexyl, methylcyclohexyl, phenyl, partially- or fully- fluorinated phenyl, methylphenyl, partially- or fully- fluorinated methylphenyl, cyclohexeny, pyridyl, imidazolyl, thiophenyl, or furanyl.

8. The electrolyte according to claim 7, wherein the second additive is selected from a group comprisingFormulas Ila to Ilh,P139474-196799. The electrolyte according to claim 1, wherein the electrolyte comprises the first additive at an amount of 0.2% to 5% and the second additive at an amount of 0.1% to 2.5%, based on a total mass of the electrolyte, optionally, the electrolyte comprises the first additive at an amount of 0.3% to 1% and the second additive at an amount of 0.1% to 0.8%, based on a total mass of the electrolyte.

10. The electrolyte according to claim 1, wherein the lithium salt is selected from a group comprising lithium hexafluorophosphate, lithium bisfluorosulfonimide, lithium bistrifluoromethanesulfonimidate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium tetrafluoro(oxalate)phosphate, lithium bis(oxalate)borate, lithium difluoro(oxalate)borate, lithium trioxalate phosphate, and lithium difluorodioxalate phosphate, optionally, the electrolyte comprises the lithium salt at an amount of 5% to 20% based on a total mass of the electrolyte, optionally, the electrolyte comprises the lithium salt at an amount of 10% to 16% based on a total mass of the electrolyte.

11. The electrolyte according to claim 1, wherein the solvent is selected from a group comprising a C3-6 carbonate compound, a C3-8 carboxylate compound, a sulfone compound, and an ether compound, optionally, the electrolyte comprises the solvent at an amount of 70% to 92% based on a total mass of the electrolyte.

12. The electrolyte according to claim 1, comprising a third additive selected from vinylene carbonate, 1,3- propane sultone, fluoroethylene carbonate, tris (trimethylsilyl) phosphate, tris (trimethylsilyl) borate, ethylene sulfate, methylene methanedisulfonate, lithium difluorophosphate, ethoxy(pentafluoro)cyclotriphosphazene, and butanedinitrile, optionally, the electrolyte comprises the third additive at an amount of 0.2% to 5% based on a total mass of the electrolyte.

13. A lithium-ion battery comprising the electrolyte according to any one of claims 1 to 12.

14. An electrical device comprising the lithium-ion battery according to claim 13.

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