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 weight percentages of 8% to 20% of the electrolyte, 0.5% to 1.5% of methylene methane disulfonate, a complementary additive in a mass percentage of less than 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 this 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 contact an ionic 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 charge and discharge cycles, 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 highly reactive electrodes.

[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 power, 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 passivation 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 consequently reducing the lithium-ion battery's capacity.

[0009] Therefore, the increase in the internal resistance of lithium-ion batteries during charge-discharge cycles or while stored in a charged state is one of the problems that causes a decrease in the performance of lithium-ion batteries. [Means for solving the problem]

[0010] To overcome this drawback, the inventors of the present invention sought to develop a novel lithium-ion battery electrolyte composition in which the increase in internal resistance during charge-discharge cycles or storage is significantly reduced compared to lithium-ion batteries of known 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] This invention primarily relates to an electrolyte characterized by containing the following components in mass percentage relative to the mass of the electrolyte. · At least a lithium salt containing a mixture of LiFSI and LiPF6 of 8% to 20%, preferably 11% to 16%, · 0.5% to 1.5% of MMDS, · At least one complementary additive, whose mass percentage is less than 5%, preferably less than 2.5%, and if the complementary additive is FEC or DTD, the mass percentage of FEC or DTD is less than 0.5%, preferably less than 0.25%, at least one complementary additive, · At least one non-aqueous organic solvent of Qsp, and contains.

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

[0014] The inventors have found, quite unexpectedly, that in the composition of the electrolyte, by combining 0.5% to 1.5% of MMDS by mass percentage and at least one complementary additive with a mass percentage of less than 5% (in the case of FEC or DTD, the mass percentage is less than 0.5%), a lithium-ion battery can be realized in which the internal resistance increases very gently during cycling or storage as compared with known lithium-ion batteries according to the prior art.

[0015] In other words, in the electrolyte composition of a lithium-ion battery, when a concentration range of MMDS of 0.5% to 1.5% by mass percentage is selected and combined with at least one complementary additive at the above-mentioned mass concentration, it is effective for controlling the internal resistance of the battery, more precisely the internal resistance. In fact, this selection makes it possible to mitigate the increase in the internal resistance during charge-discharge cycling or storage of the lithium-ion battery due to the synergistic effect with the complementary additive. This is very beneficial for the performance of the lithium-ion battery, and compared with known state-of-the-art lithium-ion batteries, the battery life is extended and the output power is also improved.

[0016] When a complementary additive is present in the electrolytic solution as in the present invention, a passivation layer having low resistance and sufficient protection can be formed on the electrode. As a result, an increase in internal resistance over time, that is, during the cycle and storage of the battery, particularly an increase in internal resistance in a charged state and / or at a temperature exceeding room temperature can be suppressed.

[0017] Furthermore, the inventors have surprisingly found that by combining an amount of MMDS such that the mass percentage is 0.5% to 1.5%, at least one complementary additive such that the mass percentage does not exceed 5% (in the case of FEC, the mass percentage is less than 0.5%), and a mixture of LiFSI and LiPF6, impurities that may contaminate the cell can be dissolved. More specifically, during cell manufacturing, handling of various components may cause contamination of the electrolytic solution by metal impurities. These metal impurities can cause short circuits and may lead to various problems such as performance degradation, fire, and even explosion. LiFSI, an additive of LiPF6, dissolves metal impurities, particularly stainless steel. This dissolution occurs during the cell formation stage (charge-discharge cycles necessary for cell activation).

[0018] Preferably, the complementary additive can be selected alone or as a mixture from the group consisting of PS, VC, FEC, VEC, PES, BS, TMS, and DTD.

[0019] Preferably, the complementary additive is PS and / or VC. In fact, tests using the electrolytic solution 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).

[0020] As described above, the total mass percentage of the complementary additive does not exceed 5%, preferably does not exceed 2.5%. If the complementary additive is FEC or DTD, the mass percentage of FEC or DTD is less than 0.5%, preferably less than 0.25%.

[0021] For complementary additives other than FEC and DTD, 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%.

[0022] In one embodiment of the present invention, the total mass percentage of complementary additives is 0.25% to 5%, preferably 1% to 2.5%.

[0023] 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%

[0024] In the electrolyte composition according to the present invention, the lithium salt ensures the ionic conductivity of lithium ions in the lithium-ion battery.

[0025] 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.

[0026] Preferably, the lithium salt is a mixture of LiFSI and LiPF6.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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).

[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 70% It is a mixture containing [the specified ingredient].

[0036] 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].

[0037] 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.

[0038] 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.

[0039] Preferably, the mass percentage of the carboxylic acid ester relative to the total mass of the electrolyte does not exceed 30%.

[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. • 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%, • At least one complementary additive selected from PS and VC, 0.25% to 4%, 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%, • At least one complementary additive selected from PS and VC, in an amount of 0.25% to 4%, preferably 0.5% to 2%. Qsp includes at least one non-aqueous organic solvent selected from EC, EMC, and DMC. Includes.

[0042] 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%, • 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%~79%, preferably 60%~79% DMC 0%~60%, preferably 0%~40% Includes.

[0043] The present invention also relates to a lithium-ion battery comprising the electrolyte according to the present invention as described above.

[0044] 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.

[0045] The positive electrode comprises a positive electrode current collector and a positive electrode active material layer. 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.

[0046] 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.

[0047] 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]

[0048] 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 internal resistance 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 internal resistance 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 internal resistance 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 has been stored. [Modes for carrying out the invention]

[0049] Examples

[0050] Experiments were conducted using the electrolyte solution according to the present invention and the electrolyte solution of a comparative example.

[0051] 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 1%, • PS 0.5%, VC 1%, EC 24.6%, • EMC 57.3% Includes.

[0052] 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.

[0053] 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").

[0054] 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.

[0055] 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.

[0056] 1a) Preparation of electrolyte according to the present invention

[0057] Under a controlled atmosphere, solvents EC and EMC were mixed. Next, additives 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.

[0058] lb) Preparation of electrolyte for comparative example

[0059] 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.

[0060] 2) Manufacturing of the positive electrode

[0061] 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].

[0062] 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.

[0063] 3) Manufacturing of the negative electrode

[0064] 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].

[0065] 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.

[0066] 4) Manufacturing of lithium-ion batteries

[0067] The positive electrode, negative electrode, and polypropylene separator were assembled and placed in a plastic pouch called a cell, or "pouch cell." An electrolyte solution was injected into this pouch, and it was then vacuum-sealed to obtain a lithium-ion battery.

[0068] Degradation experiment using constant current cycling

[0069] 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 internal resistance was periodically measured at 25°C during 400 charge-discharge cycles.

[0070] Table 1 below shows, • Lithium-ion battery according to the present invention (hereinafter referred to as "the present invention") • Comparative example lithium-ion battery (hereinafter referred to as "comparative example") The internal resistance R is expressed as a function of the number of charge-discharge cycles, where the internal resistance R is expressed as a percentage with the initial internal resistance R0 set to 100%.

[0071] [Table 1]

[0072] Therefore, the graph in Figure 1 shows the change in the internal resistance R of the lithium-ion battery according to the present invention as a function of the number of charge and discharge cycles (where R is expressed as a percentage with the initial internal resistance "R0" set to 100%, and the vertical axis is R / R0(%)), and the change in the internal resistance of the comparative example.

[0073] Table 1 and the graph in Figure 1 show that after 400 charge-discharge cycles, the increase in the internal resistance of the lithium-ion battery according to the present invention is much lower than that of the comparative lithium-ion battery (specifically, 108.5% versus approximately 159.9%).

[0074] Degradation experiment due to storage

[0075] 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.

[0076] Tables 2 and 3 below show the functions of the number of weeks of storage, • 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"). The internal resistance R is shown, where R is expressed as a percentage with the initial internal resistance ("R0") set to 100%.

[0077] [Table 2]

[0078] [Table 3]

[0079] Therefore, the graph in Figure 2 shows the change in the internal resistance of the lithium-ion battery and the comparative example according to the present invention as a function of the number of weeks of storage (the value R is expressed as a percentage with the initial internal resistance "R0" set to 100%, and the vertical axis is R / R0(%)).

[0080] As can be seen in Tables 2 and 3 along with the graph in Figure 2, the increase in the internal resistance of the lithium-ion battery according to the present invention after 20 weeks of storage is much lower than that of the comparative lithium-ion battery (specifically, 131.7% vs. 186.1%).

[0081] These experiments demonstrate that a lithium-ion battery with higher performance in terms of internal resistance 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, - At least one complementary additive, Its mass percentage is less than 5%, preferably less than 2.5%, and if the complementary additive is fluoroethylene carbonate or ethylene sulfate, the mass percentage of fluoroethylene carbonate or ethylene sulfate 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, trimethylene sulfate, and ethylene 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 carbonate and methyl carbonate, methyl carbonate and propyl carbonate, methyl carbonate and isopropyl carbonate, methyl carbonate and butyl carbonate, and ethyl carbonate and propyl carbonate. The electrolyte according to any one of claims 1 to 5.

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

8. The electrolyte comprises the following components in mass percentage relative to the mass of the electrolyte: ・At least lithium bis(fluorosulfonyl)imide and LiPF ６ A lithium salt containing a mixture containing at least one of them is 8% to 20%, preferably 11% to 16%, and - Methylene methane disulfonate in a concentration of 0.5% to 1.5%, - At least one complementary additive selected from 1,3-propanesultone and vinylene carbonate is added in an amount of 0.25% to 4%, preferably 0.5% to 2%, - An amount (QSP: Quantite suffisante pour) of at least one non-aqueous organic solvent selected from ethylene carbonate, ethyl carbonate, 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 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 79%, preferably 60% to 79%, of ethyl carbonate and 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.

Images