Electrolyte and lithium-ion battery containing the electrolyte

Abstract

The present invention relates to an electrolyte for a lithium-ion battery, comprising a lithium salt containing a mixture of at least one of LiFSI and LiPF6 in mass percentage of 8% to 20% of the electrolyte mass, 0.5% to 1.5% of methylene methane disulfonate, 0.25% to 2% of ethylene sulfate, a complementary additive in mass percentage of less than 2.5%, and a sufficient amount of a non-aqueous organic solvent. The present invention also relates to a lithium-ion battery containing the above electrolyte.

Description

Technical Field

[0001] The present invention relates to an electrolytic solution and a lithium-ion battery including the electrolytic solution.

Background Art

[0002] In the context of the present invention, a lithium-ion battery refers to a device that electrochemically stores energy and releases it as needed. Following the English term "battery", the term "lithium-ion battery" is also used when referring to this type of electrical energy storage battery. A lithium-ion battery is an electrical generating device composed of two conductors (specifically, electrodes) that come into contact with an ion conductor (electrolytic solution) in the form of a liquid, gel, or solid.

[0003] The principle of a lithium-ion battery is based on the reversible exchange of lithium ions between a positive electrode (generally a lithium transition metal oxide such as cobalt or manganese dioxide) and a negative electrode (generally graphite) during the charge-discharge cycle, and its cycle life is very good. The electrolytic solution is aprotic (generally a dissolved lithium hexafluorophosphate salt, hereinafter abbreviated as "LiPF6"), passivates the negative electrode, and prevents the deterioration of the highly reactive electrode.

[0004] Lithium-ion batteries have the following advantages in particular. · High energy density due to the properties of lithium · Low self-discharge · Excellent cycle life

[0005] Therefore, lithium-ion batteries are widely adopted in mobile applications (phones, automobiles) and systems that utilize renewable energy (solar, wind power).

[0006] More specifically, with the increasing consumption of portable electronic devices, electric vehicles, and renewable energy storage, the development of safe, low-cost lithium-ion batteries with high energy density and high output is essential. Therefore, in order to realize more efficient lithium-ion batteries, the focus of research and development is not only on the development of new electrode materials, but also on the development of new electrolyte compositions. [Overview of the project] [Problems that the invention aims to solve]

[0007] Over time and with the number of charge-discharge cycles, lithium-ion batteries tend to lose capacity and increase in internal resistance, eventually becoming unusable.

[0008] The following physicochemical phenomena cause degradation in lithium-ion batteries: When the graphite electrode is in contact with the electrolyte, especially during the initial charging of the battery, a lithium layer accumulates on the electrode, naturally reducing the amount of lithium ions available in the electrolyte. This so-called "passivation layer" electrically insulates the electrode from the electrolyte, thus preventing and / or suppressing subsequent reactions between the electrode and the electrolyte. This slightly reduces the battery's capacity and increases its internal resistance. Over time and with the number of charging cycles, this passivation layer increases in thickness, further increasing the internal resistance and resulting in a decrease in the lithium-ion battery's capacity.

[0009] Thus, the change in capacity relative to the nominal value is one of the visible effects of aging degradation in lithium-ion batteries and causes a decrease in battery performance. In this regard, within the framework of the present invention, the capacity of a lithium-ion battery is defined as the amount of charge that the battery can supply during discharge. This is the integral value (Ah) of the current that can be supplied in one hour, and corresponds to the transition of the battery from a fully charged state to a 0% charged state. Capacity measurement is performed by a constant current cycle test at a constant current density. [Means for solving the problem]

[0010] The inventors of this invention sought to overcome this drawback by developing a novel electrolyte composition for lithium-ion batteries that exhibits improved capacity retention during charge-discharge cycles or storage at high temperatures compared to lithium-ion batteries known from the prior art.

[0011] In describing the present invention, the following abbreviations will be used. BS: Butansulton • CMC: Carboxymethylcellulose DEC: Diethyl carbonate • DMC: Dimethyl carbonate DTD: Ethylene sulfate EC: Ethylene carbonate • EMC: Ethyl methyl carbonate FEC: Fluoroethylene carbonate LCO: LiCoO2 • LiBOB: Lithium bis(oxalato) borate • LiDFOB: Lithium difluoro(oxalato) borate LFP: LiFePO4 • LiFSI: Lithium bis(fluorosulfonyl)imide • LiPF6: Lithium hexafluorophosphate ·LiTFSI:LiN(SO2CF3)2 LMO:LiMn2O4 MMDS: Methylene methane disulfonate NCA: Li(Ni,Co,Al)O2 • NMC: Li(Ni,Mn,Co)O2 • NMP: N-methyl-2-pyrrolidone PC: Propylene Carbonate PES:1-propene-1,3-sultone • PS: 1,3-propanesultone PVDF: Polyvinylidene fluoride SBR: Styrene-butadiene TMS: Trimethylene sulfate VEC: Vinyl ethylene carbonate ·VC: Vinylene carbonate

[0012] The present invention mainly relates to an electrolytic solution characterized by containing the following components in mass percentage relative to the mass of the electrolytic solution. That is · A lithium salt containing at least a mixture of 8% to 20%, preferably 11% to 16% of LiFSI and LiPF6, and · 0.5% to 1.5% of MMDS, and · 0.25% to 2%, preferably 0.5% to 1.5% of DTD, and · At least one complementary additive, the mass percentage thereof is less than 5%, preferably less than 2.5%. If the complementary additive is FEC, the mass percentage of FEC is less than 0.5%, preferably less than 0.25%, at least one complementary additive, and · At least one non-aqueous organic solvent of Qsp, and are included.

[0013] "Qsp" is an acronym for "Quantite suffisante pour (sufficient amount)", which means an amount such that when adding the mass percentage of the solvent in the electrolytic solution and the mass percentages of all other components of the electrolytic solution, the total becomes 100%.

[0014] The inventors have unexpectedly found that in the composition of the electrolytic solution, by combining MMDS with a mass percentage of 0.5% to 1.5%, DTD with a mass percentage of 0.25% to 2%, and at least one complementary additive with a mass percentage preferably less than 2.5% (in the case of FEC, the mass percentage is less than 0.5%), a lithium-ion battery with a higher capacity retention rate during cycling or storage can be realized compared to lithium-ion batteries known from the prior art.

[0015] In other words, in the electrolyte composition of the lithium-ion battery, select 0.5% to 1.5% as the mass content of MMDS, select 0.25% to 2% as the mass content of DTD, and further combine at least one kind of the additives with the above mass contents. In addition to the capacity of the battery, the maintenance rate of its capacity is also improved. In fact, this selection can achieve an excellent capacity maintenance rate during the cycling or storage of the lithium-ion battery due to the synergistic effect with the complementary additive(s). This is very beneficial for the performance of the lithium-ion battery, so the battery life is prolonged compared with the lithium-ion battery known from the prior art.

[0016] Furthermore, the inventors have surprisingly discovered that by combining an amount of MMDS with a mass percentage of 0.5% to 1.5%, an amount of DTD with a mass percentage of 0.25% to 2%, at least one kind of complementary additive with a mass percentage not exceeding 5% (less than 0.5% in the case of FEC), and a mixture of LiFSI and LiPF6, it is possible to dissolve impurities that may contaminate the cell. More specifically, during the manufacture of the cell, due to the handling of various parts of the cell, contamination of the electrolyte by metal impurities can occur. These metal impurities can cause a short circuit, which can result in various problems such as performance degradation, fire, and even explosion. LiFSI, an additive to LiPF6, dissolves metal impurities, especially stainless steel. This dissolution occurs during the cell formation stage (the charge-discharge cycles required for the activation of the cell).

[0017] Preferably, the complementary additive can be selected alone or as a mixture from the group consisting of PS, VC, FEC, VEC, PES, BS, and TMS.

[0018] Preferably, the complementary additive is PS and / or VC. In fact, tests using the electrolyte of the present invention containing PS and / or VC show very conclusive results. VC passively treats the graphite electrode. PS suppresses the generation of gas (which should be avoided).

[0019] As mentioned above, the total mass percentage of complementary additives should not exceed 5%, preferably not exceeding 2.5%. If the complementary additive is FEC, the mass percentage of FEC should be less than 0.5%, preferably less than 0.25%.

[0020] For complementary additives other than FEC, the mass percentage of each complementary additive is preferably 0.25% to 2%, and more preferably 0.5% to 1.5%. In other words, The mass percentage of PS is 0.25% to 2%, preferably 0.5% to 1.5%. The mass percentage of VC is 0.25% to 2%, preferably 0.5% to 1.5%. The mass percentage of VEC is 0.25% to 2%, preferably 0.5% to 1.5%. The mass percentage of BS is 0.25% to 2%, preferably 0.5% to 1.5%. The mass percentage of TMS is 0.25% to 2%, preferably 0.5% to 1.5%. The mass percentage of PES is 0.25% to 2%, preferably 0.5% to 1.5%.

[0021] In one embodiment of the present invention, the total mass percentage of the complementary additive is 0.25% to 5%, preferably 0.25% to 2.5%, and more preferably 1% to 2.5%.

[0022] In a preferred embodiment of the present invention, the electrolyte contains PS and VC as complementary additives in the following mass percentages. PS: 0.25% to 2%, preferably 0.5% to 1.5% • VC: 0.25% to 2%, preferably 0.5% to 1.5%

[0023] In the electrolyte composition according to the present invention, the lithium salt ensures the ionic conductivity of lithium ions in the lithium-ion battery.

[0024] As described above, the lithium salt consists of at least a mixture of LiFSI and LiPF6. The lithium salt may further contain LiBF4, LiTFSi, LiClO4, LiAsF6, LiBOB, and LiDFOB, either individually or as mixtures thereof.

[0025] Preferably, the lithium salt is a mixture of LiFSI and LiPF6.

[0026] Lithium salt LiPF6 offers the best balance in terms of electrochemical stability, thermal stability, ionic conductivity, and passivation of aluminum foil, which functions as a current collector for the positive electrode.

[0027] In one embodiment of the present invention, with respect to the lithium salt, the electrolyte is expressed in a mass percentage relative to the mass of the electrolyte, • LiFSI 1.5%~4%, preferably 2%~3.5% LiPF 68.5% to 16%, preferably 10% to 14% Includes.

[0028] The electrolyte according to the present invention may contain one or more non-aqueous organic solvents. This ensures proper function of the lithium-ion battery and optimizes the conductivity of the electrolyte.

[0029] For example, it may consist of one or more non-aqueous organic solvents selected from cyclic or linear carbonate esters. These cyclic or linear carbonate esters can be used to adjust the conductivity and viscosity of the electrolyte of the present invention, thereby improving the cycle characteristics and power characteristics of lithium-ion batteries.

[0030] More specifically, the cyclic carbonate ester can be selected from the group consisting of EC, PC, 1,2-butylene carbonate, and 2,3-butylene carbonate.

[0031] Linear carbonate esters can be selected from the group consisting of DMC, DEC, dipropyl carbonate, dibutyl carbonate, EMC, methylpropyl carbonate, methyl isopropyl carbonate, methyl butyl carbonate, and ethyl propyl carbonate.

[0032] Therefore, the non-aqueous organic solvent can be selected individually or as a mixture thereof from the group consisting of EC, PC, 1,2-butylene carbonate, 2,3-butylene carbonate, DMC, DEC, dipropyl carbonate, dibutyl carbonate, EMC, methylpropyl carbonate, methyl isopropyl carbonate, methyl butyl carbonate, and ethylpropyl carbonate.

[0033] Preferably, the non-aqueous organic solvent is selected from the group consisting of EC, EMC, and DMC, either individually or as a mixture thereof. These solvents, in synergistic effect with the complementary additives added in the aforementioned mass percentages, achieve good ionic conductivity of the electrolyte without inducing degradation of the electrode material (especially graphite).

[0034] In one embodiment of the present invention, the non-aqueous organic solvent is expressed in mass percentage relative to the total mass of the solvent, EC 30%, • EMC 70% It is a mixture containing [something].

[0035] In one embodiment of the present invention, the non-aqueous organic solvent is expressed in mass percentage relative to the total mass of the solvent, EC 30%, EMC 40%, DMC 30% It is a mixture containing [the specified ingredient].

[0036] This non-aqueous organic solvent may further contain at least one carboxylic acid ester to improve the conductivity of the electrolyte and reduce its viscosity.

[0037] The carboxylic acid ester may be selected individually or as a mixture thereof from the group consisting of methylformic acid, ethylformic acid, propylformic acid, isopropylformic acid, methylpropanoate, ethylpropanoate, propylpropanoate, isopropylpropanoate, methyl acetate, ethyl acetate, propyl acetate, and isopropyl acetate.

[0038] Preferably, the mass percentage of the carboxylic acid ester relative to the total mass of the electrolyte does not exceed 30%.

[0039] In a preferred embodiment of the present invention, the electrolyte is expressed in terms of mass percentage relative to the mass of the electrolyte. • A lithium salt containing at least a mixture of LiFSI and LiPF6, in an amount of 8% to 20%, preferably 11% to 16%. MMDS 0.5%~1.5%, • DTD 0.25%~2%, preferably 0.5%~1.5% • At least one complementary additive selected from PS and VC, 0.25% to 4%, preferably 0.25% to 2.5%, more preferably 0.5% to 2%. Qsp includes at least one non-aqueous organic solvent selected from EC, EMC, and DMC. Includes.

[0040] In a preferred embodiment of the present invention, the electrolyte is expressed in terms of mass percentage relative to the mass of the electrolyte. • LiFSI 1.5%~4%, preferably 2%~3.5% • LiPF 68.5%~16%, preferably 10%~14% MMDS 0.5%~1.5%, • DTD 0.25%~2%, preferably 0.5%~1.5% • At least one complementary additive selected from PS and VC, 0.25% to 4%, preferably 0.25% to 2.5%, more preferably 0.5% to 2%. Qsp includes at least one non-aqueous organic solvent selected from EC, EMC, and DMC. Includes.

[0041] In a preferred embodiment of the present invention, the electrolyte is expressed in terms of mass percentage relative to the mass of the electrolyte. • LiFSI 1.5%~4%, preferably 2%~3.5% • LiPF 68.5%~16%, preferably 10%~14% MMDS 0.5%~1.5%, • DTD 0.25%~2%, preferably 0.5%~1.5% • PS 0.25%~2%, preferably 0.5%~1.5% • VC 0.25%~2%, preferably 0.5%~1.5% EC 10%~50%, preferably 20%~40%, EMC 10%~78%, preferably 60%~78% DMC 0%~60%, preferably 0%~40% Includes.

[0042] The present invention also relates to a lithium-ion battery comprising the electrolyte according to the present invention as described above.

[0043] More specifically, this lithium-ion battery comprises a positive electrode, a negative electrode, a separator between the two electrodes, and the electrolyte according to the present invention described above.

[0044] The positive electrode comprises a positive electrode current collector and a positive electrode active material layer. The properties of the positive electrode are within the realm of what a person skilled in the art can fully understand. For example, the positive electrode active material can be selected from the group consisting of LFP, NMC, NCA, LCO, and LMO. Preferably, the positive electrode active material is NMC.

[0045] The negative electrode comprises a negative electrode current collector and a negative electrode active material layer. For example, the negative electrode active material can be selected from the group consisting of graphite, silicon, silicon oxide, silicon alloy, tin, tin oxide, tin alloy, and lithium titanate. Preferably, the negative electrode active material is graphite.

[0046] Preferably, the nominal voltage of the lithium-ion battery does not exceed 3.8V, and more preferably does not exceed 3.6V. [Brief explanation of the drawing]

[0047] The present invention will be better understood by reading the detailed description below while referring to the attached drawings, which show experimental data regarding the change in capacity retention of the lithium-ion battery according to the present invention and the lithium-ion battery of comparative examples as non-limiting examples. [Figure 1] Figure 1 is a graph showing the change in capacity retention rate of the lithium-ion battery according to the present invention and the lithium-ion battery of a comparative example as a function of the number of charge and discharge cycles of the battery. [Figure 2] Figure 2 is a graph showing the change in capacity retention rate of the lithium-ion battery according to the present invention and the lithium-ion battery of a comparative example as a function of the number of weeks the battery is stored at 60°C. [Modes for carrying out the invention]

[0048] Examples

[0049] Experiments were conducted using the electrolyte solution according to the present invention and the electrolyte solution of a comparative example.

[0050] The electrolyte according to the present invention is, in terms of mass percentage relative to the total mass of the electrolyte • LiPF 612.6%, • LiFSI 3.1%, MMDS 0.5% • DTD 1%, • PS 0.5%, VC 0.5%, EC 24.5%, • EMC 57.3% Includes.

[0051] The electrolyte used for the overwrite is calculated as a mass percentage relative to the total mass of the electrolyte. • LiPF 613.5%, • LiFSI 3.1%, VC 1%, • PS 1%, EC 24.4%, • EMC 57% Includes.

[0052] VC and PS have been widely known and used as additives for lithium-ion battery electrolytes for many years. Therefore, the electrolyte of the comparative example described above is particularly useful for comparing the performance of a lithium-ion battery containing the electrolyte according to the present invention (hereinafter referred to as "the lithium-ion battery according to the present invention") with a lithium-ion battery containing the electrolyte of this comparative example (hereinafter referred to as "the comparative example lithium-ion battery").

[0053] The lithium-ion battery according to the present invention and the lithium-ion battery of the comparative example were manufactured according to the following steps 1 to 4.

[0054] More specifically, the only difference between manufacturing the lithium-ion battery according to the present invention (i.e., step 1a) and the comparative example lithium-ion battery (i.e., step 1b) is the electrolyte preparation step. In other words, steps 2-4 were identical for both lithium-ion batteries.

[0055] 1a) Preparation of electrolyte according to the present invention

[0056] Under a controlled atmosphere, solvents EC and EMC were mixed. Next, additives DTD, MMDS, VC, and PS were added to the solvent mixture. Lithium salts LiPF6 and LiFSI were dissolved in the solvent and additive mixture. The amounts of these various components of the electrolyte of the present invention were appropriately selected to obtain the electrolyte of the present invention as described above.

[0057] lb) Preparation of electrolyte for comparative example

[0058] Under a controlled atmosphere, solvents EC and EMC were mixed. Next, additives VC and PS were added to the solvent mixture. Lithium salts LiPF6 and LiFSI were dissolved in the solvent and additive mixture. The amounts of these various components in the comparative electrolyte were appropriately selected to obtain the comparative electrolyte as described above.

[0059] 2) Manufacturing of the positive electrode

[0060] The active material NMC is composed of a binder (PVDF) and a conductive agent (carbon black), and the following mass percentages of the total mass of the mixture of NMC, PVDF, and carbon black. • NMC 90%, PVDF 5%, • Carbon Black 5% It was mixed with [something].

[0061] Next, the mixture was dispersed in NMP until a uniform dispersion was obtained. This solution was mixed to prepare an electrode paste, which was uniformly coated onto aluminum foil to a thickness of 200 μm. After drying at room temperature and then at 100°C for 1 hour, the cathode was finally obtained by calendering.

[0062] 3) Manufacturing of the negative electrode

[0063] Graphite is used in the following mass percentages of the total mass of the mixture of graphite, CMC, and SBR, along with CMC and a binder (SBR). Graphite 92%, • CMC 4%, • SBR 4% It was mixed with [something].

[0064] This mixture was dispersed in water (solvent) to obtain a homogeneous dispersion. This electrode paste was uniformly applied to a copper foil to a thickness of 200 μm, dried at room temperature, then dried at 70°C for 1 hour, and finally calendered to obtain the negative electrode.

[0065] 4) Manufacturing of lithium-ion batteries

[0066] The positive electrode, negative electrode, and polypropylene separator were assembled and placed in a plastic pouch, also known as a "pouch cell." An electrolyte solution was then injected into this pouch, and it was vacuum-sealed to obtain a lithium-ion battery.

[0067] Degradation experiment using constant current cycling

[0068] Degradation experiments using constant current cycling were conducted as follows: The lithium-ion battery according to the present invention and the lithium-ion battery of the comparative example were subjected to a constant current (approximately 1 mA / cm²) at 45°C. 2 The batteries were subjected to a charge-discharge cycle, and their capacity was periodically measured at 25°C during 400 charge-discharge cycles.

[0069] Table 1 below shows, • Lithium-ion battery according to the present invention (hereinafter referred to as "the present invention"), and • Comparative example lithium-ion battery (hereinafter referred to as "comparative example") The capacity retention rate C relative to the nominal value "C0" is shown in detail as a function of the number of charge-discharge cycles.

[0070] [Table 1]

[0071] The graph in Figure 1 shows the change in capacity retention rate (vertical axis: C / C0 (%)) of the lithium-ion battery according to the present invention and the lithium-ion battery according to the comparative example as a function of the number of charge and discharge cycles.

[0072] Table 1 and the graph in Figure 1 show that after 400 charge-discharge cycles, the capacity retention rate of the lithium-ion battery according to the present invention is much higher than that of the comparative lithium-ion battery (specifically, 88.3% vs. 83.1%).

[0073] Degradation experiment due to storage

[0074] The storage degradation experiment was conducted as follows: The lithium-ion battery according to the present invention and the lithium-ion battery of the comparative example were stored at 60°C, and the internal resistance of these batteries was measured periodically at 25°C for 12 weeks.

[0075] Tables 2 and 3 below show the number of weeks as a function of storage at 60°C. • The lithium-ion battery of the present invention ("the present invention"), and • The lithium-ion battery used in the comparative example (referred to as the "comparative example"). This shows the capacity retention ratio C relative to the nominal value "C0".

[0076] [Table 2]

[0077] [Table 3]

[0078] The graph in Figure 2 shows the change in capacity retention rate (vertical axis: C / C0 (%)) of the lithium-ion battery of the present invention and the lithium-ion battery of the comparative example as a function of the number of weeks of storage.

[0079] Looking at Tables 2 and 3 along with the graph in Figure 2, it can be seen that after 14 weeks of storage, the capacity retention rate of the lithium-ion battery according to the present invention is much higher than that of the comparative lithium-ion battery (specifically, 83.6% vs. 73.3%).

[0080] These experiments demonstrate that a lithium-ion battery with higher capacity can be obtained by using the electrolyte according to the present invention.

Claims

1. An electrolyte, wherein the mass percentage of the mass of the electrolyte is 8% to 20%, preferably 11% to 16%, of lithium bis(fluorosulfonyl)imide and LiPF ６ A lithium salt comprising a mixture containing at least one of the following, ・0.5% to 1.5% methylene methane disulfonate, 0.25% to 2%, preferably 0.5% to 1.5% of ethylene sulfate, - At least one complementary additive, Its mass percentage is less than 2.5%, and if the complementary additive is fluoroethylene carbonate, the mass percentage of fluoroethylene carbonate is less than 0.5%, preferably less than 0.25%. At least one complementary additive, - At least one non-aqueous organic solvent in an amount (QSP: Quantite suffisante pour) such that the total mass percentage of all other components of the electrolyte is 100%, Features including, Electrolyte.

2. The complementary additive is characterized by being selected individually or as a mixture thereof from the group consisting of 1,3-propanesultone, vinylene carbonate, fluoroethylene carbonate, vinylethylene carbonate, 1-propene-1,3-sultone, butanesultone, and trimethylene sulfate. The electrolyte according to claim 1.

3. The complementary additive is characterized by being 1,3-propanesultone and / or vinylene carbonate. The electrolyte according to claim 2.

4. The lithium salt is LiBF ４ , LiN (SO ２ CF ３ ) ２ LiClO ４ LiAsF ６ The present invention is characterized by further comprising lithium bis(oxalato)borate and lithium difluoro(oxalato)borate, either alone or as a mixture thereof. The electrolyte according to any one of claims 1 to 3.

5. The lithium salts are lithium bis(fluorosulfonyl)imide and LiPF ６ It is characterized by being a mixture of The electrolyte according to claim 1.

6. The non-aqueous organic solvent is characterized by being selected individually or as a mixture thereof from the group consisting of ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, methyl butyl carbonate, and ethyl propyl carbonate. The electrolyte according to any one of claims 1 to 5.

7. The non-aqueous organic solvent is characterized by being selected from the group consisting of ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate, either individually or as a mixture thereof. The electrolyte according to claim 6.

8. The electrolyte comprises the following components in mass percentage relative to the mass of the electrolyte: ・ 8% to 20%, preferably 11% to 16%, of at least lithium bis(fluorosulfonyl)imide and LiPF ６ A lithium salt containing a mixture containing at least one of them, and ・0.5% to 1.5% methylene methane disulfonate, 0.25% to 2%, preferably 0.5% to 1.5% of ethylene sulfate, - 0.25% to 2.5%, preferably 0.5% to 2%, of at least one complementary additive selected from 1,3-propanesultone and vinylene carbonate, - An amount (QSP: Quantite suffisante pour) of at least one non-aqueous organic solvent selected from ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate, in such a quantity that the total mass percentage of all other components of the electrolyte is 100%, Features including, The electrolyte according to claim 1.

9. The electrolyte comprises the following components in mass percentage relative to the mass of the electrolyte: - 1.5% to 4%, preferably 2% to 3.5%, of lithium bis(fluorosulfonyl)imide, 8.5% to 16%, preferably 10% to 14% LiPF ６ and, ・0.5% to 1.5% methylene methane disulfonate, 0.25% to 2%, preferably 0.5% to 1.5% of ethylene sulfate, 0.25% to 2%, preferably 0.5% to 1.5% of 1,3-propanesultone, - 0.25% to 2%, preferably 0.5% to 1.5% vinylene carbonate, ・10% to 50%, preferably 20% to 40%, of ethylene carbonate, 10% to 78%, preferably 60% to 78%, of ethyl methyl carbonate, ・0% to 60%, preferably 0% to 40%, of dimethyl carbonate, Features including, The electrolyte according to claim 1.

10. A lithium-ion battery comprising the electrolyte according to any one of claims 1 to 9.

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