Electrolyte additive, electrolyte, lithium-ion battery and electrical device

Abstract

Provided is an electrolyte additive for a lithium-ion battery. The additive includes a sulfonic ester compound, and the sulfonic ester group of the sulfonic ester compound in the additive may form lithium alkyl sulfonate on an anode active material of the lithium-ion battery during a formation process, which helps to form a dense sulfur-rich interface film with high ionic conductivity. In addition, the additive includes the ring structure and unsaturated bond, such that the additive may preferentially perform ring-opening polymerization and / or addition polymerization on the surfaces of the cathode active material and the anode active material of the lithium-ion battery to form a polymer film, and the polymer film may isolate the contact between the surfaces of electrode material and the electrolyte, inhibit side reactions, and reduce a consumption of electrolyte and active lithium ion.

Description

[0001] P139473-19679

[0002] ELECTROLYTE ADDITIVE, 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 additive for a lithium-ion battery, an electrolyte, a lithium-ion battery, and an electrical device.

[0005] BACKGROUND

[0006] A lithium-ion battery has advantages of high energy density, high output power, long cycling life, and low environmental pollution, and is widely used in electronics, electric vehicles, distributed energy storage, and other fields. 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. Due to changes in the internal and external environment of the lithium-ion battery, the lithium-ion battery is easy to be exposed to high temperature environment. Partial solvent in the electrolyte may perform an oxidative decomposition reaction, and decomposition products and gases generated may affect the progress of electrochemical reaction of the lithium-ion battery, which thus causes a decrease in a service life of the battery and a decrease in an amount of stored energy. In addition, a main salt LiPFe in the lithium-ion battery is prone to decompose to produce HF at high temperature, which destroys a solid electrolyte interface (SEI) film and leads to a dissolution of metal ions (e.g. Mn, Ni) in the cathode active material, reducing battery capacity and cycling performance.

[0007] SUMMARY

[0008] Embodiments of the present disclosure seek to solve at least one of the problems existing in the related art to at least some extent.

[0009] According to a first aspect of the present disclosure, an electrolyte additive for a lithium-ion battery is provided. The electrolyte additive includes a sulfonic ester compound having a formula 1 of P139473-19679 where O is C3-C6 cycloalkane or C3-C6 cycloalkene, Ri is selected from a group including hydrogen atom, C1-C4 alkyl, C2-C4 alkenyl, C1-C4 fluoroalkyl, and C2-C4 fluoroalkenyl, R2 is selected from a group including C1-C4 alkyl, C1-C4 fluoroalkyl, C2-C6 alkenyl or C2-C6 fluoroalkeny, and the n is 0 or 1; and in which at least one of O, R and R2 includes an unsaturated bond.

[0010] The additive in the embodiments of the present disclosure can form a solid electrolyte interface (SEI) film, with high ion conductivity, on an electrode surface, which thus improves a stability of the surface of electrode material, reduces a battery impedance, and enhances a cycling performance and a high-temperature storage performance of the lithium-ion battery. Furthermore, the sulfonic ester group of the sulfonic ester compound in the additive may form lithium alkyl sulfonate on an anode active material of the lithium-ion battery during a formation process, which helps to form a dense sulfur-rich interface film with high ionic conductivity. In addition, the additive includes the ring structure and the unsaturated bond, such that the additive may preferentially perform ringopening polymerization and / or addition polymerization on the surfaces of the cathode active material and the anode active material of the lithium-ion battery to form a polymer film, and the polymer film may isolate the contact between the electrode surface and the electrolyte, inhibit side reactions, and reduce a consumption of electrolyte and active lithium ion.

[0011] In some embodiments of the present disclosure, O includes at least one unsaturated bond. The unsaturated bond on O may be easy to induce the ring-opening reaction of the O, and the sulfonic ester compound 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 polymer film.

[0012] In some embodiments of the present disclosure, Ri includes at least one unsaturated bond, and / or R2 includes at least one unsaturated bond. The sulfonic ester compound with such structure may have more polymerization sites for performing the ring-opening polymerization and the addition polymerization, thus further accelerate the polymerization efficiency. The polymer film formed on the electrode surfaces is faster and denser, which may better protect the electrodes, inhibit the side reactions, and reduce the consumption of electrolyte and active lithium ion. P139473-19679

[0013] In some embodiments of the present disclosure, Ri is hydrogen atom or C3-C4 alkenyl, and R2 is C2-C3 alkyl or C2-C3 alkenyl.

[0014] In some embodiments of the present disclosure, the formula 1 selected from a group including: formula 1 i formula 11

[0015] According to a second aspect of the present disclosure, an electrolyte of a lithium-ion battery is provided. The electrolyte includes: a lithium salt; a solvent; and an additive according to any one of the embodiments of the present disclosure. The electrolyte in the embodiments of the present disclosure includes the additive having the sulfonic ester compound, and the additive may form a SEI film, with high ion conductivity, on an electrode surface, which thus improves a stability of the surface of electrode material, reduces a battery impedance, and enhances a cycling performance and a high-temperature storage performance of the lithium-ion battery. Furthermore, the sulfonic ester group of the sulfonic ester compound in the additive may form lithium alkyl sulfonate on an anode active material of the lithium-ion battery during a formation process, which helps to form a dense sulfur-rich interface film with high ionic conductivity. In addition, the additive includes the ring P139473-19679 structure and unsaturated bond, such that the additive may preferentially perform ring-opening polymerization and / or addition polymerization on the surfaces of the cathode active material and the anode active material of the lithium-ion battery to form a polymer film, and the polymer film may isolate the contact between the electrode surfaces and the electrolyte, inhibit side reactions, and reduce a consumption of electrolyte and active lithium ion.

[0016] In some embodiments of the present disclosure, the sulfonic ester compound in the additive has an amount of 0.2wt %-5.0wt % based on a total weight of the lithium-ion battery electrolyte. The synergistic effect of the additive, which meets the condition of the amount of 0.2wt %-5.0wt %, on the cathode active material and the anode active material may be further effective.

[0017] In some embodiments of the present disclosure, the sulfonic ester compound in the additive has an amount of 0.3wt %-1.0wt % based on a total weight of the lithium-ion battery electrolyte. The synergistic effect of the additive, which meets the further condition of the amount of 0.3wt %- l.Owt %, on the cathode active material and the anode active material may be further effective.

[0018] In some embodiments of the present disclosure, the lithium salt is selected from a group including lithium hexafluorophosphate, lithium bisfluorosulfonylimide, lithium bistrifluoromethylsulfonylimide, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium tetrafluorooxalate phosphate, lithium bis(oxalate)borate, lithium difluorooxalate borate, lithium trioxalate phosphate, and lithium difluorodioxalate phosphate.

[0019] In some embodiments of the present disclosure, the lithium salt has an amount of 5.0wt %- 20.0wt % based on a total weight of the electrolyte. The lithium salt above has good stability and electrical conductivity. For example, the amount of the sulfonic ester compound may be 0.3wt %, 0.4wt %, 0.5wt %, 0.6wt %, 0.7wt %, 0.8wt %, 0.9wt %, or l.Owt %, based on a total weight of the lithium-ion battery electrolyte.

[0020] In some embodiments of the present disclosure, the lithium salt has an amount of lO.Owt %- 16.0wt % based on a total weight of the electrolyte. For example, the amount of the lithium salt may be lO.Owt %, ll.Owt %, 12.0wt %, 13.0wt %, 14.0wt %, 15.0wt %, or 16.0wt %, based on the total weight of the lithium-ion battery electrolyte.

[0021] In some embodiments of the present disclosure, the solvent is selected from a group including a C3-C6 carbonate compound, a C3-C8 carboxylate compound, a sulfone compound, and an ether compound.

[0022] In some embodiments of the present disclosure, the solvent has an amount of 70.0wt %-90.0wt % P139473-19679 based on a total weight of the electrolyte. For example, the amount of the solvent may be 70.0wt %, 75.0wt %, 80.0wt %, 85.0wt %, or 90.0wt %, based on the total weight of the lithium-ion battery electrolyte.

[0023] In some embodiments of the present disclosure, the additive includes a base additive, and the base additive is selected from a group including vinylene carbonate, 1,3 -propane sultone, fluoroethylene carbonate, tris (trimethyl silyl) phosphate, tris (trimethyl silyl) borate, vinyl sulfate, methylene methanedi sulfonate, lithium difluorophosphate, pentafluoroethoxycyclotriphosphazene, butanedinitrile, citraconic anhydride or succinic anhydride. In some embodiments, the base additive may include at least one component selected from the above group. For example, the base additive may include vinylene carbonate and lithium difluorophosphate.

[0024] In some embodiments of the present disclosure, a single component of the base additive has an amount of 0.3wt %-3.0wt % based on a total weight of the electrolyte. For example, the amount of the single component of the base additive may be 0.3wt %, l.Owt %, 2.0wt %, or 3.0wt %, based on the total weight of the lithium-ion battery electrolyte.

[0025] According to a third aspect of the present disclosure, a lithium-ion battery is provided. The lithium-ion battery includes the electrolyte according to any one of the embodiments of the present disclosure. The lithium-ion battery of the embodiments of the present disclosure has an excellent stability of the surface for 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.

[0026] According to a fourth aspect of the present disclosure, an electrical device is provided. The electrical device includes the lithium-ion battery according to any one of the embodiments of the present disclosure. The electrical device of the embodiments of the present disclosure has advantages of long service life, excellent usage performance and improved high-temperature resistance.

[0027] 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.

[0028] BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to clearly illustrate technical solutions of embodiments of the disclosure, a description of drawings used in the embodiments is given below. P139473-19679

[0030] FIG. 1 is a gas chromatogram (GC) spectrum of a sulfonic ester compound prepared according to an embodiment of the present disclosure.

[0031] FIG. 2 is a GC spectrum of a sulfonic ester compound prepared according to another embodiment of the present disclosure.

[0032] DETAILED DESCRIPTION

[0033] 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.

[0034] 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.

[0035] 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%.

[0036] 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 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. P139473-19679

[0037] Electrolyte additive for lithium-ion battery

[0038] The embodiments of the present disclosure provides an electrolyte additive for a lithium-ion battery. The additive includes an unsaturated sulfonic ester compound. Compared with the lithium- ion battery including electrolyte with the additive in the related arts, the lithium-ion battery, including the electrolyte with the additive in the embodiments of the present disclosure, has an improved cycling performance and an improved high-temperature resistance.

[0039] In the embodiments of the present disclosure, the additive includes a sulfonic ester compound (i.e. a sulfonate compound), and the sulfonic ester compound has a formula 1 of,

[0040] 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.

[0041] In the formula of the sulfonic ester compound, 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. The C3-C6 cycloalkane and the C3-C6 cycloalkene both contain a ring structure, so that O may perform a ring-opening reaction.

[0042] In the formula of the sulfonic ester compound, Ri is selected from a group including hydrogen atom, C1-C4 alkyl, C2-C4 alkenyl, C1-C4 fluoroalkyl, and C2-C4 fluoroalkenyl. The C1-C4 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-C4 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-C4 fluoroalkyl is an alkyl with 1-4 carbon atoms, on which the hydrogen atom is partially or completely replaced by the fluorine atom, and the C1-C4 fluoroalkyl has a saturated chemical bond structure. The C2-C4 fluoroalkenyl is an alkenyl with 2-4 carbon atoms, on which the hydrogen atom is partially or completely replaced by the fluorine atom, and the C2-C4 fluoroalkenyl has at least one carboncarbon double bond.

[0043] In the formula of the sulfonic ester compound, R2 is selected from a group including C1-C4 P139473-19679 alkyl, C1-C4 fluoroalkyl, C2-C6 alkenyl or C2-C6 fluoroalkeny, in which the C2-C6 alkenyl is an alkenyl with 2-6 carbon atoms, and the C2-C6 fluoroalkeny is an alkenyl with 2-6 carbon atoms, on which the hydrogen atom is partially or completely replaced by the fluorine atom.

[0044] The “n” in the formula above is 0 or 1. At least one of O, R and R2 includes an unsaturated bond.

[0045] The additive in the embodiments of the present disclosure can form a solid electrolyte interface (SEI) film, with high ion conductivity, on an surfaces of electrode material, which thus improves a stability of the surface of electrode material, reduces a battery impedance, and enhances a cycling performance and a high-temperature storage performance of the lithium-ion battery. Furthermore, the sulfonic ester group of the sulfonic ester compound in the additive may form lithium alkyl sulfonate on an anode active material of the lithium-ion battery during a formation process, which helps to form a dense sulfur-rich interface film with high ionic conductivity. In addition, the additive includes the ring structure and unsaturated bond, such that the additive may preferentially perform ring-opening polymerization and / or addition polymerization on the surfaces of the cathode active material and the anode active material of the lithium-ion battery to form a polymer film, and the polymer film may isolate the contact between the surfaces of electrode material and the electrolyte, inhibit side reactions, and reduce a consumption of electrolyte and active lithium ion. Therefore, the lithium-ion battery, including the electrolyte with the additive in the embodiments of the present disclosure, has the improved cycling performance and the improved high-temperature resistance through a synergistic effect of the additive on the cathode active material and the anode active material.

[0046] In some embodiments of the present disclosure, O includes at least one unsaturated bond. The unsaturated bond on O may be easy to induce the ring-opening reaction of the O, and the sulfonic ester compound 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 polymer film.

[0047] In some embodiments of the present disclosure, O includes at least one unsaturated bond. Ri includes at least one unsaturated bond, and / or R2 includes at least one unsaturated bond. The sulfonic ester compound with such structure may have more polymerization sites for performing the ringopening polymerization and the addition polymerization, thus further accelerate the polymerization efficiency. The polymer film formed on the surfaces of electrode material is faster and denser, which P139473-19679 may better protect the electrodes, inhibit the side reactions, and reduce the consumption of electrolyte and active lithium ion. 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 1c below, O includes one unsaturated bond, Ri includes one unsaturated bond and R2 includes one unsaturated bond.

[0048] In some embodiments of the present disclosure, Ri is hydrogen atom or C3-C4 alkenyl, and R2 is C2-C3 alkyl or C2-C3 alkenyl.

[0049] In some embodiments of the present disclosure, the formula 1 selected from a group including: formula li formula 1 formula Ik 1

[0050] As shown in the formula la- 11, the sulfonic ester compound in the embodiments of the present disclosure includes the ring structure and at least one unsaturated bond.

[0051] For example, in the formula la, O of the sulfonic ester compound 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 sulfonic ester compound having P139473-19679 the formula la may perform the ring-opening polymerization and the addition polymerization synchronously on the surfaces of the cathode active material and the anode active material of the lithium-ion battery, to form the polymer films on the surfaces of electrode material. The polymer film may isolate the contact between the surfaces of electrode material and the electrolyte, inhibit side reactions, and reduce the consumption of electrolyte and active lithium ion.

[0052] In another example, O in the formula If is cyclopentene, Ri is hydrogen atom, R2 is isopropyl, and the “n” is 1. In the formula If, only O include the unsaturated bond. The sulfonic ester compound having the formula If may perform the ring-opening polymerization on the surfaces of electrode material of the lithium-ion battery, and also may perform the addition polymerization after the ring-opening reaction, such that the polymer films on the surfaces of electrode material may be formed to protect the electrodes.

[0053] Electrolyte of lithium-ion battery

[0054] The embodiments of the present disclosure provides an electrolyte of a lithium-ion battery. The electrolyte includes the additive according to any one of the embodiments of the present disclosure. The lithium-ion battery, including the electrolyte in the embodiments of the present disclosure, has an improved cycling performance and an improved high-temperature resistance.

[0055] In the embodiments of the present disclosure, the electrolyte includes a lithium salt, a solvent; and an additive according to any one of the embodiments of the present disclosure.

[0056] The electrolyte in the embodiments of the present disclosure includes the additive having the sulfonic ester compound, and the additive may form a SEI film, with high ion conductivity, on an surface of electrode material, which thus improves a stability of the surface of electrode material, reduces a battery impedance, and enhances a cycling performance and a high-temperature storage performance of the lithium-ion battery. Furthermore, the sulfonic ester group of the sulfonic ester compound in the additive may form lithium alkyl sulfonate on an anode active material of the lithium-ion battery during a formation process, which helps to form a dense sulfur-rich interface film with high ionic conductivity. In addition, the additive includes the ring structure and unsaturated bond, such that the additive may preferentially perform ring-opening polymerization and / or addition polymerization on the surfaces of the cathode active material and the anode active material of the lithium-ion battery to form a polymer film, and the polymer film may isolate the contact between the surfaces of electrode material and the electrolyte, inhibit side reactions, and reduce a P139473-19679 consumption of electrolyte and active lithium ion.

[0057] In some embodiments of the present disclosure, the sulfonic ester compound in the additive has an amount of 0.2wt %-5.0wt % based on a total weight of the lithium-ion battery electrolyte. For example, the amount of the sulfonic ester compound may be 0.2wt %, 0.5wt %, l.Owt %, 1.5wt %, 2. Owt %, 2.5wt %, 3.0wt %, 3.5wt %, 4.0wt %, 4.5wt %, or 5.0wt %, based on the total weight of the lithium-ion battery electrolyte. The synergistic effect of the additive, which meets the condition of the amount of 0.2wt %-5.0wt %, on the cathode active material and the anode active material may be further effective. If the amount of the sulfonic ester compound is too few (for example, less than 0.2wt %), it may result in the inability to form the effective SEI film and the dense polymer film, which may affect the stability of the surface of electrode material and cannot effectively suppress side reactions, resulting in a fast consumption of electrolyte and active lithium ion. If the amount of the sulfonic ester compound is too much (for example, more than 5.0wt %), it may cause the polymer film formed to be too thick, which may affect the exchange of lithium ions between the cathode active material and the anode active material, and decrease the electrochemical performance of the lithium-ion battery.

[0058] In some embodiments of the present disclosure, the sulfonic ester compound in the additive has an amount of 0.3wt %-1.0wt % based on a total weight of the lithium-ion battery electrolyte. For example, the amount of the sulfonic ester compound may be 0.3wt %, 0.4wt %, 0.5wt %, 0.6wt %, 0.7wt %, 0.8wt %, 0.9wt %, or 1.Owt %, based on a total weight of the lithium-ion battery electrolyte. The synergistic effect of the additive, which meets the further condition of the amount of 0.3wt %- l.Owt %, on the cathode active material and the anode active material may be further effective.

[0059] In some embodiments of the present disclosure, the lithium salt is selected from a group including lithium hexafluorophosphate (LiPFe), lithium bisfluorosulfonylimide (HFSI), lithium bistrifluoromethylsulfonylimide (LiBEs), lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate (Li Cl Ch), lithium tetrafluorooxalate phosphate, lithium bis(oxalate)borate, lithium difluorooxalate borate (LiODFB), lithium trioxalate phosphate, and lithium difluorodioxalate phosphate.

[0060] In some embodiments of the present disclosure, the lithium salt has an amount of 5. Owt %- 20. Owt % based on a total weight of the electrolyte. For example, the amount of the lithium salt may be 5. Owt %, 10. Owt %, 15. Owt %, or 20. Owt %, based on the total weight of the lithium-ion battery electrolyte. In some embodiments, the lithium salt, which meets the condition of the amount of P139473-19679

[0061] 5.0wt %-20.0wt %, is referred as a main lithium salt in the electrolyte.

[0062] In some embodiments of the present disclosure, the lithium salt has an amount of lO.Owt %- 16.0wt % based on a total weight of the electrolyte. For example, the amount of the lithium salt may be lO.Owt %, ll.Owt %, 12.0wt %, 13.0wt %, 14.0wt %, 15.0wt %, or 16.0wt %, based on the total weight of the lithium-ion battery electrolyte.

[0063] In some embodiments of the present disclosure, the solvent is selected from a group including a C3-C6 carbonate compound, a C3-C8 carboxylate compound, a sulfone compound, and an ether compound. The C3-C6 carbonate compound is a carbonate compound with 3-6 carbon atoms, where the carbonate compound refers to a compound in which the hydrogen atoms of two hydroxyl groups (-OH) in a carbonate molecule are partially or completely replaced by alkyl groups (R, R’), and has a general formula of RO-CO-OR’. The C3-C8 carboxylate compound is a carboxylate compound with 3-8 carbon atoms, in which the carboxylate compound has a general formula of R-COO-R, where the RCO- in this formula represents a carboxylic acid part, while-OR’ represents an alcohol part. The sulfone compound has a general formula of RI-SO2-R2. The ether compound has a general formula of R-O-R’, where the R may be same as or different from the R’.

[0064] In some embodiments of the present disclosure, the solvent has an amount of 70.0wt %-90.0wt % based on a total weight of the electrolyte. For example, the amount of the solvent may be 70.0wt %, 75.0wt %, 80.0wt %, 85.0wt %, or 90.0wt %, based on the total weight of the lithium-ion battery electrolyte.

[0065] In some embodiments of the present disclosure, the additive comprises a base additive, and the base additive is selected from a group including vinylene carbonate, 1,3-propane sultone, fluoroethylene carbonate, tris (trimethyl silyl) phosphate, tris (trimethyl silyl) borate, vinyl sulfate, methylene methanedi sulfonate, lithium difluorophosphate, pentafluoroethoxycyclotriphosphazene, butanedinitrile, citraconic anhydride or succinic anhydride. In some embodiments, the base additive may include at least one component selected from the above group. For example, the base additive may include vinylene carbonate and lithium difluorophosphate.

[0066] In some embodiments of the present disclosure, a single component of the base additive has an amount of 0.3wt %-3.0wt % based on a total weight of the electrolyte. For example, the amount of the single component of the base additive may be 0.3wt %, l.Owt %, 2.0wt %, or 3.0wt %, based on the total weight of the lithium-ion battery electrolyte. In some embodiments, the base additive include a plurality of components, in which the amount of the single component meet this condition P139473-19679 of 0.3wt %-3.Owt %, and the amounts of the plurality of components may be the same or be different.

[0067] As an example, the base additive include vinylene carbonate and lithium difluorophosphate, in which the amount of the vinylene carbonate is 0.3wt %-3.0wt % based on the total weight of the electrolyte, and the amount of the lithium difluorophosphate is 0.3wt %-3.0wt % based on the total weight of the electrolyte. For example, the amount of the vinylene carbonate may be 0.1 wt %, and the amount of the lithium difluorophosphate may be 2.4wt %.

[0068] Lithium-ion battery

[0069] 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.

[0070] A lithium-ion battery may include a positive electrode plate, a negative electrode plate, and an electrolyte. The lithium-ion battery may be a battery module or a battery pack, which may be applied in electrical devices, such as mobile terminals and vehicles. The electrical device of the present disclosure is powered by the lithium-ion battery and has advantages of long service life, excellent usage performance and improved high-temperature resistance.

[0071] [Positive electrode plate]

[0072] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector. The positive electrode film layer includes the cathode active material.

[0073] 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 film layer is provided on either or both of the two surfaces.

[0074] The positive electrode film layer includes the cathode active material. The cathode active material may be selected from materials capable of absorbing and releasing lithium.

[0075] 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 (LiFePCh), lithium manganese phosphate (LiMnPCU), lithium cobalt P139473-19679 phosphate (LiCoPCU), iron pyrophosphate (Li2FeP2O?), lithium cobaltate (LiCoCh), spinel -type lithium manganate (LiM CU), 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.sCo0.15Al0.05O2), lithium nickel cobalt manganese oxides (LiNixCoyMni-x.yO2, 0<x<l, 0<y<l, 0<x+y<l, e.g., LiNii / 3Coi / 3Mni / 3O2, LiNio.5Coo.2Mno.3O2, LiNio.eCoo.2Mno.2O2, LiNio.sCoo.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).

[0076] The above cathode active material may be modified, for example is doped, coated, or both doped and coated with a modification compound.

[0077] 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.

[0078] 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-tetrafluoroethylene terpolymer, tetrafluoroethylene- hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0079] In some embodiments, the positive electrode film 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. P139473-19679

[0080] 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.

[0081] [Negative electrode plate]

[0082] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector. The negative electrode film layer includes an anode active material.

[0083] 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 surfaces.

[0084] 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.

[0085] 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, silicon-nitrogen 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).

[0086] In some embodiments, the negative electrode film layer optionally includes a binder. The binder P139473-19679 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).

[0087] 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.

[0088] In some embodiments, the negative electrode film layer optionally includes other adjuvants, such as thickeners (e.g. sodium carboxymethylcellulose (CMC -Na)).

[0089] 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.

[0090] 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.

[0091] 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.

[0092] In some embodiments, the lithium-ion battery includes an outer package. The outer package is used to package the electrodes and the electrolyte.

[0093] 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.

[0094] The shape of the lithium-ion battery may be cylindrical, square or any other shape, which is not limited in the present disclosure. P139473-19679

[0095] Experimental Section

[0096] 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.

[0097] Method for synthesizing the sulfonic ester compound having formula la

[0098] 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 of (0.03mol) 2 -propene- 1 -sulfonyl chloride was weighed and dissolved in 15mL of anhydrous di chloromethane. The di chloromethane solution containing 2-propene-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 . 0.739 g (0.01 mol) of Li2CO3and 20 u L (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 MgSCh was added into the organic phase to dry for 12 h. After 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).

[0099] Method for synthesizing the sulfonic ester compound having formula lb

[0100] 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 di chloromethane 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 . 0.09 g P139473-19679

[0101] (0.0037 mol) of LiOH and 20 L (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 MgSO4 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.

[0102] Method for synthesizing the sulfonic ester compound having formula 1c

[0103] 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 tri ethylamine was placed in an ice water bath at 0°C for 10 minutes. 4.217g of 2-propenyl- 1 -sulfonyl chloride was weighed and dissolved in 15mL of anhydrous di chloromethane. The dichloromethane solution containing 2 -propenyl- 1 -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 sulfonic ester compound having the formula 1c. 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.

[0104] Method for synthesizing the sulfonic ester compound having formula Id

[0105] 2.502g (0.025mol) of cyclopentane 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 cyclopentane methanol and the trimethylamine was placed in an ice water bath at 0°C for 10 minutes. 4.217g (0.03mol) of 2-propenyl-l -sulfonyl chloride was weighed and dissolved in 15mL of anhydrous di chloromethane. The di chloromethane 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 Li2CO3and 20 u L (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 MgSC 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. P139473-19679

[0106] Method for synthesizing the sulfonic ester compound having formula le

[0107] 2.452g of 3 -cyclopentene- 1 -methanol was weighed and added in a reaction flask, then 3.033g of tri ethylamine was added into the reaction flask. The reaction flask containing the 3-cyclopentene-

[0108] 1 -methanol and the tri ethylamine was placed in an ice water bath at 0°C for 10 minutes. 4.217g of

[0109] 2-propenyl-l -sulfonyl chloride was weighed and dissolved in 15mL of anhydrous di chloromethane. 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 sulfonic ester compound 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.

[0110] Method for synthesizing the sulfonic ester compound having formula If

[0111] 2.452g (0.025mol) of 3 -cyclopentene- 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 -cyclopentene- 1 -methanol and the trimethylamine was placed in an ice water bath at 0°C for 10 minutes. 4.260g (0.03mol) of isopropyl sulfonyl chloride was weighed and dissolved in 15mL of anhydrous di chloromethane. The di chloromethane solution containing isopropyl 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 Li2CO3and 20 u L (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 MgSC 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).

[0112] Method for synthesizing the sulfonic ester compound having formula 1

[0113] 2.803g of 3 -cyclohexene- 1 -methanol was weighed and added in a reaction flask, then 3.033g of tri ethylamine was added into the reaction flask. The reaction flask containing the 3-cyclohexene- P139473-19679

[0114] 1 -methanol and the tri ethylamine was placed in an ice water bath at 0°C for 10 minutes. 4.260g of isopropyl sulfonyl 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 sulfonic ester compound having the formula 1g. 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.

[0115] Method for synthesizing the sulfonic ester compound having formula Ih

[0116] 3.805g (0.025mol) of perilla alcohol compound 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 perilla alcohol compound 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 di chloromethane 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 20 u L (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 MgSC 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 molecular weight of the product was 244 (the molecular weight theoretical value of the compound having formula Ih is 244.3).

[0117] The method for synthesizing formula Ij, Ik, and 11 are essentially the same as the methods for synthesizing formula 1 a- li, so they will not be elaborated upon here.

[0118] Method for preparing electrolyte

[0119] Ethylene Carbonate (EC), Diethyl Carbonate (DEC), and Ethyl Methyl Carbonate (EMC) with certain amounts were weighed in an argon atmosphere (EbO<0.1 ppm, O2<0.1 ppm), respectively, P139473-19679 and mixed EC, DEC and EMC evenly to obtain the solvent. After cooling the solvent, the lithium salt (for example, LiPFe) and the additive containing the sulfonic ester compound were added in the solvent to obtain a solution, and then the solution was stirred evenly to obtain the electrolyte.

[0120] Method for preparing lithium-ion battery

[0121] According to the method for preparing the lithium-ion battery of the present disclosure, a negative electrode plate, a separator and a positive electrode plate were rolled into a battery cell in an order of negative electrode plate-separator-positive electrode plate. Then the battery cell was placed into a groove of an outer package, and the electrolyte prepared according to the present disclosure was injected into the outer package. A soft package lithium-ion battery was obtained by sealing the battery cell in the outer package.

[0122] Test methods

[0123] 1. Tests for prepared sulfonic ester compound

[0124] Material tests were performed on the sulfonic ester compound obtained from the methods for synthesizing the sulfonic ester compound. As examples, the sulfonic ester compound having formula lb and the sulfonic ester compound having formula Id, which were obtained from the above method, were tested by a gas chromatography -mass spectrometry (GC-MS) analyzer.

[0125] As shown in FIG. 1, the GC spectrum for the sulfonic ester compound 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 sulfonic ester compound having formula lb obtained according to the method embodiment of the present disclosure has a GC purity of about 98.5%. In addition, the sulfonic ester compound having formula lb obtained has a GC MS molecular weight of about 204, which conforms to the chemical formula of the sulfonic ester compound. A detailed analysis of the spectrum in FIG. 1 is shown in the following table.

[0126] Table 1 Analysis of FIG. 1 P139473-19679

[0127] As shown in FIG. 2, the GC spectrum for the sulfonic ester compound 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 sulfonic ester compound having formula Id obtained according to the method embodiment of the present disclosure has a GC purity of about 98.2%. In addition, the sulfonic ester compound having formula Id obtained has a GC MS molecular weight of about 204, which conforms to the chemical formula of the sulfonic ester compound. A detailed analysis of the spectrum in FIG. 2 is shown in the following table.

[0128] Table 2 Analysis of FIG. 2

[0129] 2. Tests for performances of lithium-ion battery

[0130] ALiNio.5Coo.2Mno.3O2 graphite soft package lithium-ion battery (e.g. 4.25 V) was used for tests of battery rate, cycling, and storage, and tested by the Xinwei charge -discharge testing system.

[0131] 2. 1. Cycling performance test at room temperature

[0132] 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 500 cycles at 25 °C according to the above conditions. DCR values Ro of the lithium-ion batteries after 500 cycles were recorded according to the following DCR testing method. P139473-19679

[0133] Capacity retention rate (%) of the lithium-ion battery after 500 cycles=(discharge capacity of the 500th cycle / discharge capacity of the first cycle) X 100%.

[0134] 2.2. High temperature cycling performance test at 45 °C

[0135] 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 500 cycles at 45 °C according to the above conditions.

[0136] Capacity retention rate (%) of the lithium-ion battery after 500 cycles=(discharge capacity of the 500th cycle / discharge capacity of the first cycle) X 100%.

[0137] 2.3. High temperature storage test at 60 °C

[0138] 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 56 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 56 days of storage were calculated according to the following formula: residual capacity retention rate = Qa / Qo X 100 %; capacity recovery retention rate = Qb / Qo X 100 %.

[0139] 2.4. DCR testing

[0140] 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 P139473-19679 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:

[0141] R=(Ui-U2) / (l4c);

[0142] DCR increase rate=(Rb-Ro) / Ro X 100%.

[0143] 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.

[0144] Examples

[0145] Inventive Example 1 (IE1)

[0146] The electrolyte for IE1 was prepared according to the corresponding method above. The electrolyte includes LiPFe, the additive and the solvent, in which the LiPFe had an amount of 12.5wt % based on a total weight of the electrolyte, the additive included the sulfonic ester compound having the formula la and vinylene carbonate (VC) acted as the base additive, where the sulfonic ester compound had an amount of 0.5wt % based on the total weight of the electrolyte, and the VC had an amount of 0.5wt % based on the total weight of the electrolyte, and the solvent included EC, DEC and EMC with a weight ratio of 3 :2: 5.

[0147] Inventive Example 2 (IE2)

[0148] 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 sulfonic ester compound had the formula lb.

[0149] Inventive Example 3 (IE3)

[0150] 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 sulfonic ester compound had the formula 1c.

[0151] Inventive Example 4 (IE4)

[0152] 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 sulfonic ester compound had the formula Id.

[0153] Inventive Example 5 (IE5)

[0154] The electrolyte for IE5 was prepared according to the corresponding method above. The P139473-19679 composition of the electrolyte was the same as that of the electrolyte for IE1 expect that the sulfonic ester compound had the formula le.

[0155] Inventive Example 6 (IE6)

[0156] 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 sulfonic ester compound had the formula If.

[0157] Inventive Example 7 (IE7)

[0158] 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 sulfonic ester compound had the formula 1g.

[0159] Inventive Example 8 (IE8)

[0160] 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 sulfonic ester compound had the formula Ih.

[0161] Inventive Example 9 (IE9)

[0162] 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 amount of the sulfonic ester compound was 0.2wt %.

[0163] Inventive Example 10 (IE 10)

[0164] The electrolyte for IE 10 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 amount of the sulfonic ester compound was 0.3wt %.

[0165] Inventive Example 11 (IE11)

[0166] The electrolyte for IE11 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 amount of the sulfonic ester compound was l.Owt %.

[0167] Inventive Example 12 (IE 12)

[0168] The electrolyte for IE 12 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 amount of the sulfonic ester compound was 5.0wt %.

[0169] Inventive Example 13 (IE 13) P139473-19679

[0170] The electrolyte for IE 13 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 additive did not contain the VC.

[0171] Inventive Example 14 (IE 14)

[0172] The electrolyte for IE 14 was prepared according to the corresponding method above. The composition of the electrolyte was the same as that of the electrolyte for IE3 expect that the additive did not contain the VC.

[0173] Inventive Example 15 (IE 15)

[0174] The electrolyte for IE15 was prepared in the same way as IE1 expect that the additive contains the sulfonic ester compound with an amount of 0.1 wt %.

[0175] Inventive Example 16 (IE 16)

[0176] The electrolyte for IE16 was prepared in the same way as IE1 expect that the additive contains the sulfonic ester compound with an amount of 6.0wt %.

[0177] Comparative Example 1 (CE1)

[0178] The electrolyte for CE1 was prepared in the same way as IE1 expect that the electrolyte did not contain the additive.

[0179] Comparative Example 2 (CE2)

[0180] The electrolyte for CE2 was prepared in the same way as IE1 expect that the additive only contains the VC, and did not contain the sulfonic ester compound.

[0181] Comparative Example 3 (CE3)

[0182] The electrolyte for CE3 was prepared in the same way as IE1 expect that the additive contains the VC with an amount of 5.0wt %, and did not contain the sulfonic ester compound. P139473-19679

[0183] Table 4 Results of cycling performance test

[0184] As we can see from the results of IE1 to IE8, benefiting from the additive containing both the sulfonic ester compound and the base additive, the lithium-ion battery has an excellent cycling performance at room temperature (25 °C) and high temperature (45 °C).

[0185] By comparing the results of IE1, IE9 to IE12, and IE15 to IE16, the lithium-ion battery has an excellent cycling performance at room temperature (25 °C) and high temperature (45 °C) because of the addition of the additive containing both the sulfonic ester compound and the base additive. It P139473-19679 can also be noted that the amount of sulfonic ester compound in the additive has a preferred range, not that the higher the amount of sulfonic ester compound, the better the cycling performance. Excessive or insufficient amount of sulfonic ester compound may have adverse effects on the cycling performance. As we can see from the results of IE1, IE9 to IE12, and IE15 to IE16, the lithium-ion battery in IE1 exhibits the best cycling performance, where the amount of sulfonic ester compound is 0.5 wt %.

[0186] By comparing the results of IE1, IE3, IE13, IE14, CE1 to CE3, the lithium-ion battery, without any additives, in CE1 exhibited the worst cycling performance, while the lithium-ion battery, with the addition of VC, in CE2 exhibited a slightly enhanced cycling performance by comparing with CE1. However, the lithium-ion battery, with the additive in the present disclosure, in IE1, IE3, IE13 or IE14 exhibited a significant improved cycling performance by comparing with CE1 to CE3, even if the amount of VC reaches 5.0wt % in CE3. By comparing the results of IE1, IE3, IE 13 and IE 14, the additive containing both the sulfonic ester compound and the base additive seems to provide a better improvement effect on the cycling performance by comparing with the additive only containing the sulfonic ester compound.

[0187] Table 5 Results of storage test P139473-19679

[0188] As we can see from the results of IE1 to IE8, benefiting from the additive containing both the sulfonic ester compound and the base additive, the lithium-ion battery has an excellent high- temperature storage performance.

[0189] By comparing the results of IE1, IE9 to IE12, and IE15 to IE16, the lithium-ion battery has an excellent high-temperature storage performance because of the addition of the additive containing both the sulfonic ester compound and the base additive. It can also be noted that the amount of sulfonic ester compound in the additive has a preferred range. Excessive or insufficient amount of sulfonic ester compound may have adverse effects on the high-temperature storage performance. As we can see from the results of IE1, IE9 to IE12, and IE15 to IE16, the lithium-ion battery in IE1 exhibits the best high-temperature storage performance, where the amount of sulfonic ester compound is 0.5 wt %.

[0190] By comparing the results of IE1, IE3, IE13, IE14, CE1 to CE3, the lithium-ion battery, without any additives, in CE1 exhibited the worst high-temperature storage performance, while the lithium- ion battery, with the addition of VC, in CE2 exhibited a slightly enhanced high-temperature storage performance by comparing with CE1. However, the lithium-ion battery, with the additive in the present disclosure, in IE1, IE3, IE13 or IE14 exhibited a significant improved high-temperature storage performance and a reduced DCR increase rate by comparing with CE1 to CE3, even if the amount of VC reaches 5.0wt % in CE3. By comparing the results of IE1, IE3, IE 13 and IE 14, the additive containing both the sulfonic ester compound and the base additive seems to provide a better improvement effect on the high-temperature storage performance by comparing with the additive only containing the sulfonic ester compound. Furthermore, the addition of the additive containing both the sulfonic ester compound and the base additive in the electrolyte may significantly decrease the DCR increase rate.

[0191] 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 P139473-19679 embodiment or example of the present disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0192] 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

P139473-19679CLAIMS1. An electrolyte additive for a lithium-ion battery, comprising a sulfonic ester compound having a formula 1 ofwhere kJ is C3-C6 cycloalkane or C3-C6 cycloalkene, Ri is selected from a group comprising hydrogen atom, C1-C4 alkyl, C2-C4 alkenyl, C1-C4 fluoroalkyl, and C2-C4 fluoroalkenyl, R2 is selected from a group comprising C1-C4 alkyl, C1-C4 fluoroalkyl, C2-C6 alkenyl or C2-C6 fluoroalkeny, and the n is 0 or 1; and wherein at least one of O, Ri, and R2 comprises an unsaturated bond.

2. The electrolyte additive according to claim 1, wherein kJ comprises at least one unsaturated bond.

3. The electrolyte additive according to claim 2, wherein Ri comprises at least one unsaturated bond, and / or R2 comprises at least one unsaturated bond.

4. The electrolyte additive according to claim 1, wherein Ri is hydrogen atom or C3-C4 alkenyl, and R2 is C2-C3 alkyl or C2-C3 alkenyl.

5. The electrolyte additive according to claim 4, the formula 1 selected from a group comprising:P139473-19679formula li fonnula 1formula Ik 16. An electrolyte of a lithium-ion battery, comprising: a lithium salt; a solvent; and an additive according to any one of the claims 1 to 4.

7. The electrolyte according to claim 5, wherein the sulfonic ester compound in the additive has an amount of 0.2wt %-5.0wt % based on a total weight of the lithium-ion battery electrolyte.

8. The electrolyte according to claim 6, wherein the sulfonic ester compound in the additive has an amount of 0.3wt %-1.0wt % based on a total weight of the lithium-ion battery electrolyte.

9. The electrolyte according to claim 5, wherein the lithium salt is selected from a group comprising lithium hexafluorophosphate, lithium bisfhrorosulfonylimide, lithium bistrifluoromethylsulfonylimide, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithiumP139473-19679 perchlorate, lithium tetrafluorooxalate phosphate, lithium bis(oxalate)borate, lithium difluorooxalate borate, lithium trioxalate phosphate, and lithium difluorodioxalate phosphate; and / or the lithium salt has an amount of 5.0wt %-20.0wt % based on a total weight of the electrolyte.

10. The electrolyte according to claim 9, wherein the lithium salt has an amount of lO.Owt %- 16.0wt % based on a total weight of the electrolyte.

11. The electrolyte according to claim 5, wherein the solvent is selected from a group comprising a C3-C6 carbonate compound, a C3-C8 carboxylate compound, a sulfone compound, and an ether compound.

12. The electrolyte according to claim 5, wherein the solvent has an amount of 70.0wt %- 90.0wt % based on a total weight of the electrolyte.

13. The electrolyte according to claim 5, wherein the additive comprises a base additive, and the base additive is selected from a group comprising vinylene carbonate, 1,3 -propane sultone, fluoroethylene carbonate, tris (trimethyl silyl) phosphate, tris (trimethyl silyl) borate, vinyl sulfate, methylene methanedi sulfonate, lithium difluorophosphate, pentafluoroethoxycyclotriphosphazene, butanedinitrile, citraconic anhydride or succinic anhydride.

14. The electrolyte according to claim 13, wherein a single component of the base additive has an amount of 0.3wt %-3.0wt % based on a total weight of the electrolyte.

15. A lithium-ion battery comprising the electrolyte according to any one of claims 6 to 14.

16. An electrical device comprising the lithium-ion battery according to claim 15.

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