Lithium salt mixtures and their use as battery electrolytes

Abstract

The present invention relates to a mixture containing lithium bis(fluorosulfonyl)imide; lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and lithium hexafluorophosphate; as well as to an electrolyte composition containing said mixture, and uses thereof.

Description

[Technical field]

[0001] This patent application relates to mixtures of lithium salts and their use as battery electrolytes. [Background technology]

[0002] A lithium-ion or lithium-sulfur battery includes at least a negative electrode (anode), a positive electrode (cathode), a separator, and an electrolyte. The electrolyte generally consists of a lithium salt dissolved in a solvent, typically a mixture of organic carbonates, to obtain a good compromise between viscosity and dielectric constant. Additives can then be added to improve the stability of the electrolyte salt.

[0003] The most widely used salts include LiPF 6 (lithium hexafluorophosphate), which has some of the required qualities, but which exhibits the drawback of decomposing on reaction with water to form hydrofluoric acid (HF). The HF formed can lead to dissolution of the cathode material. Thus, LiPF 6 Reactions between EDTA and residual water can affect battery life and may pose safety hazards, especially in the use of lithium-ion batteries in personal vehicles.

[0004] Therefore, other salts such as LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) and LiFSI (lithium bis(fluorosulfonyl)imide) have been developed.

[0005] In the field of batteries, there is a continuing need for the development of new salts that make it possible to improve the service life, and / or electrochemical stability, and / or performance qualities of the battery, such as cycling stability, and / or irreversible capacity degradation of the battery, and / or power performance qualities, especially over a wide temperature range, such as from about -25°C to about 60°C. Description of the invention

[0006] [Mixture] This patent application is - Lithium bis(fluorosulfonyl)imide (LiFSI); - lithium 2-trifluoromethyl-4,5-dicyanoimidazolate (LiTDI); and - Lithium hexafluorophosphate (LiPF 6 ) It relates to a mixture comprising (preferably consisting essentially of, preferentially consisting of)

[0007] According to one embodiment, the mixture comprises: - 1 mol% to 98 mol% lithium bis(fluorosulfonyl)imide (LiFSI); - 1 mol% to 98 mol% of lithium 2-trifluoromethyl-4,5-dicyanoimidazolate (LiTDI); and - 1mol% to 98mol% lithium hexafluorophosphate (LiPF 6 ) comprises (preferably consists essentially of, preferentially consists of).

[0008] According to the present invention, the mole percentage is relative to the total number of moles of the compound present in the mixture. In the context of the present invention, "lithium bis(fluorosulfonyl)imide salt", "lithium bis(sulfonyl)imide", "LiFSI", "LiN(FSO 2 ) 2 ", "lithium bis(sulfonyl)imide" and "lithium bis(fluorosulfonyl)imide" are used equivalently. In the context of the present invention, the "total number of moles of compounds of a mixture" corresponds to the sum of the number of moles of each compound present in the mixture.

[0009] Lithium 2-trifluoromethyl-4,5-dicyanoimidazolate, known as LiTDI, has the following structure: Impurities may be present in the mixture, for example in a proportion of less than 3000 ppm, preferably less than 1000 ppm, in particular less than 500 ppm, relative to the total weight of the mixture. In the context of the present invention, the term "ppm" or "parts per million" is understood to mean ppm by weight. The impurities are LiFSI, LiTDI, or LiPF 6 They may be present in the salts in a proportion of, for example, less than 3000 ppm, preferably less than 1000 ppm, in particular less than 500 ppm, for example less than 300 ppm, relative to the total weight of each salt.

[0010] Typically, LiFSI can be obtained according to any known method, such as, for example, the methods described in WO 2015 / 158979, WO 2011 / 065502 or else in WO 2011 / 149095. Typically, LiTDI can be obtained according to any known method, such as, for example, the methods described in WO 2013 / 072591 or WO 2010 / 023413. Typically, LiPF 6 can be obtained according to any known method, for example the methods described in US Pat. No. 3,607,020, US Pat. No. 3,907,977 or else in JP 60-251109 A.

[0011] According to one embodiment, the mixture according to the invention comprises at least 5 mol %, preferably at least 10 mol %, preferentially at least 15 mol %, even more preferentially at least 20 mol %, advantageously at least 25 mol % and even more advantageously at least 30 mol % LiFSI; and / or at least 5 mol %, preferably at least 10 mol %, preferentially at least 15 mol %, even more preferentially at least 20 mol % and advantageously at least 25 mol % of LiTDI; and / or at least 10 mol %, preferentially at least 15 mol %, even more preferentially at least 20 mol %, advantageously at least 25 mol % LiPF 6 Contains:

[0012] According to one embodiment, the content of LiFSI in the mixture according to the invention is selected from one of the following molar percentages: 1% to 99%, 1% to 95%, 5% to 90%, 5% to 85%, 5% to 80%, 5% to 75%, 5% to 70%, 5% to 65%, 5% to 50%, 5% to 45%, 10% to 99%, 10% to 95%, 10% to 90%, 10% to 85%, 10% to 80%, 10% to 75%, 10% to 70%, 10% to 65%, 10% to 60%, 10% to 85%. %, 10%~55%, 10%~50%, 10%~45%, 15%~99%, 15%~95%, 15%~90%, 15%~85%, 15%~80%, 15%~75%, 15%~70%, 15%~65%, 15%~60%, 15%~55%, 15%~50%, 15%~45%, 20%~99%, 20%~95%, 20%~90%, 20%~85%, 20%~80%, 20%~75%, 20%~70%, 20%~65%, 20%~60%, 20 %~55%, 20%~50%, 20%~45%, 25%~99%, 25%~95%, 25%~90%, 25%~85%, 25%~80%, 25%~75%, 25%~70%, 25%~65%, 25%~60%, 25%~55%, 25%~50%, 25%~45%, 30%~99%, 30%~95%, 30%~90%, 30%~85%, 30%~80%, 30%~75%, 30%~70%, 30%~65%, 30%~60%, 30%~55 %, 30%-50%, 30%-45%, 35%-99%, 35%-95%, 35%-90%, 35%-85%, 35%-80%, 35%-75%, 35%-70%, 35%-65%, 35%-60%, 35%-55%, 35%-50%, 40%-99%, 40%-95%, 40%-90%, 40%-85%, 40%-80%, 40%-75%, 40%-70%, 40%-65%, 40%-60%, 40%-55%, or 40%-50%.

[0013] According to one embodiment, the content of LiTDI in the mixture according to the invention is selected from one of the following molar percentages: 1% to 99%, 1% to 95%, 5% to 90%, 5% to 85%, 5% to 80%, 5% to 75%, 5% to 70%, 5% to 65%, 5% to 50%, 5% to 45%, 10% to 99%, 10% to 95%, 10% to 90%, 10% to 85%, 10% to 80%, 10% to 75%, 10% to 70%, 10% to 65%, 10% to 60%, 10% to 60%, 10% to 85%, 10% to 80%, 10% to 75%, 10% to 70%, 10% to 65%, 10% to 60%, 10% to 85 ...65%, 10% to 65%, 10% to %, 10%~55%, 10%~50%, 10%~45%, 15%~99%, 15%~95%, 15%~90%, 15%~85%, 15%~80%, 15%~75%, 15%~70%, 15%~65%, 15%~60%, 15%~55%, 15%~50%, 15%~45%, 20%~99%, 20%~95%, 20%~90%, 20%~85%, 20%~80%, 20%~75%, 20%~70%, 20%~65%, 20%~60%, 20 %~55%, 20%~50%, 20%~45%, 25%~99%, 25%~95%, 25%~90%, 25%~85%, 25%~80%, 25%~75%, 25%~70%, 25%~65%, 25%~60%, 25%~55%, 25%~50%, 25%~45%, 30%~99%, 30%~95%, 30%~90%, 30%~85%, 30%~80%, 30%~75%, 30%~70%, 30%~65%, 30%~60%, 30%~55 %, 30%-50%, 30%-45%, 35%-99%, 35%-95%, 35%-90%, 35%-85%, 35%-80%, 35%-75%, 35%-70%, 35%-65%, 35%-60%, 35%-55%, 35%-50%, 40%-99%, 40%-95%, 40%-90%, 40%-85%, 40%-80%, 40%-75%, 40%-70%, 40%-65%, 40%-60%, 40%-55%, or 40%-50%.

[0014] According to one embodiment, LiPF in the mixture according to the invention 6is selected from one of the following mole percentages: 1% to 99%, 1% to 95%, 5% to 90%, 5% to 85%, 5% to 80%, 5% to 75%, 5% to 70%, 5% to 65%, 5% to 50%, 5% to 45%, 10% to 99%, 10% to 95%, 10% to 90%, 10% to 85%, 10% to 80%, 10% to 75%, 10% to 70%, 10% to 65%, 10% to 60%, 10% to 55%, 10% to 5 ... %~45%, 15%~99%, 15%~95%, 15%~90%, 15%~85%, 15%~80%, 15%~75%, 15%~70%, 15%~65%, 15%~60%, 15%~55%, 15%~50%, 15%~45%, 20%~99%, 20%~95%, 20%~90%, 20%~85%, 20%~80%, 20%~75%, 20%~70%, 20%~65%, 20%~60%, 20%~55%, 20%~50% , 20%~45%, 25%~99%, 25%~95%, 25%~90%, 25%~85%, 25%~80%, 25%~75%, 25%~70%, 25%~65%, 25%~60%, 25%~55%, 25%~50%, 25%~45%, 30%~99%, 30%~95%, 30%~90%, 30%~85%, 30%~80%, 30%~75%, 30%~70%, 30%~65%, 30%~60%, 30%~55%, 30%~ 50%, 30%-45%, 35%-99%, 35%-95%, 35%-90%, 35%-85%, 35%-80%, 35%-75%, 35%-70%, 35%-65%, 35%-60%, 35%-55%, 35%-50%, 40%-99%, 40%-95%, 40%-90%, 40%-85%, 40%-80%, 40%-75%, 40%-70%, 40%-65%, 40%-60%, 40%-55%, or 40%-50%.

[0015] According to one embodiment, the mixture is - 5mol%~90mol% LiFSI; - 5 mol% to 90 mol% LiTDI; and - 5mol% to 90mol% LiPF 6 comprises (preferably consists essentially of, preferentially consists of).

[0016] According to one embodiment, the mixture is - 20mol%~90mol% LiFSI; - 5 mol% to 60 mol% LiTDI; and - 5mol% to 60mol% LiPF 6 comprises (preferably consists essentially of, preferentially consists of).

[0017] According to one embodiment, the mixture is - 30mol%-70mol% LiFSI; - 10 mol% to 50 mol% LiTDI; and - 10mol% to 50mol% LiPF 6 comprises (preferably consists essentially of, preferentially consists of).

[0018] According to one embodiment, the mixture is - 35mol%-60mol% LiFSI; - 15 mol% to 50 mol% LiTDI; and - 15mol% to 50mol% LiPF 6 comprises (preferably consists essentially of, preferentially consists of).

[0019] According to one embodiment, the mixture is - 35mol%-50mol% LiFSI; - 20 mol% to 40 mol% LiTDI; and - 20mol% to 40mol% LiPF 6 comprises (preferably consists essentially of, preferentially consists of).

[0020] According to one embodiment, the mixture is - 35mol%-45mol% LiFSI; - 25 mol% to 35 mol% LiTDI; and - 25mol%~35mol% LiPF 6 comprises (preferably consists essentially of, preferentially consists of).

[0021] According to one embodiment, the mixture is - 40 mol% LiFSI; 30 mol% LiTDI; and - 30mol% LiPF 6 comprises (preferably consists essentially of, preferentially consists of).

[0022] Preferably, the mixture is - 50 mol% LiFSI; 20 mol% LiTDI; and - 30mol% LiPF 6 comprises (preferably consists essentially of, preferentially consists of).

[0023] According to one embodiment, in the mixture according to the invention, the content of LiFSI is equal to or greater than the content of LiTDI and / or LiPF 6 The content is equal to or greater than LiTDI.

[0024] According to one embodiment, LiFSI / LiTDI / LiPF 6 The molar ratios are as follows: - 1 / 1 / 1 to 10 / 1 / 1, preferably 1 / 1 / 1 to 5 / 1 / 1, preferentially 1 / 1 / 1 to 2 / 1 / 1. In particular LiFSI / LiTDI / LiPF 6 The molar ratio of is 4 / 3 / 3; - 1 / 1 / 1 to 1 / 10 / 1, preferably 1 / 1 / 1 to 1 / 5 / 1 and preferentially 1 / 1 / 1 to 1 / 2 / 1; - 1 / 1 / 1 to 1 / 1 / 10, preferably 1 / 1 / 1 to 1 / 1 / 5 and preferentially 1 / 1 / 1 to 1 / 1 / 2; - 5 / 1 / 3 to 5 / 4 / 3, preferably 5 / 1 / 3 to 5 / 2 / 3, preferentially LiFSI / LiTDI / LiPF6 The molar ratio is 5 / 2 / 3.

[0025] According to one embodiment, the LiFSI / LiPF in the mixture 6 The molar ratio of LiFSI / LiPF in the mixture is between 1 and 10, preferably between 1 and 5, and preferentially between 1 and 2. 6 The molar ratio is 4 / 3 or 5 / 3.

[0026] The present patent application also relates to the use of the mixtures as defined above in batteries, for example lithium-ion batteries, in particular in a temperature range between -30° C. and 65° C., preferentially between -25° C. and 60° C., preferably above 25° C., preferably between 25° C. and 65° C., advantageously between 40° C. and 60° C. For example in mobile devices such as mobile phones, cameras, tablet or laptop computers, electric vehicles or renewable energy storage.

[0027] [Electrolyte composition] The present invention also relates to an electrolyte composition, in particular for Li-ion batteries, containing a mixture of a lithium salt as defined above, at least one solvent and optionally at least one electrolyte additive.

[0028] Preferably, the electrolyte composition contains no alkali metal or alkaline earth metal salts other than those in the above mixture. Preferably, the electrolyte composition is LiFSI, LiPF 6 and contains no lithium salts other than LiTDI. In particular, the electrolyte composition does not contain LiTFSI. Preferably, LiFSI, LiPF 6 and LiTDI salts comprise 100% of all salts present in the composition.

[0029] In the context of the present invention, "electrolyte composition", "electrolyte" and "electrolytic composition" are used interchangeably.

[0030] According to a preferred embodiment, the electrolyte composition contains from 1% to 99% by weight, preferably from 5% to 99%, advantageously from 20% to 95% of said mixture relative to the total weight of the composition. According to a preferred embodiment, the electrolyte composition contains from 1% to 99% by weight of solvent relative to the total weight of the composition, preferably from 5% to 99%, advantageously from 20% to 95%.

[0031] According to one embodiment, the molar concentration of said mixture in the electrolyte composition is less than or equal to 5 mol / l, advantageously less than or equal to 4 mol / l, preferably less than or equal to 2 mol / l, preferentially less than or equal to 1.5 mol / l, in particular less than or equal to 1.1 mol / l, for example less than or equal to 1 mol / l.

[0032] According to a preferred embodiment, LiFSI, LiTDI and LiPF in the electrolyte composition 6 The molar concentration of is [LiFSI] + [LiTDI] + [LiPF 6 ]≦5 mol / l, preferably ≦2 mol / l, preferentially ≦1.5 mol / l, even more preferentially ≦1.1 mol / l, such as ≦1 mol / l.

[0033] According to one embodiment, the electrolyte composition comprises: - LiFSI from 0.01 to 0.98 mol / l; - LiTDI from 0.01 to 0.98 mol / l; and - 0.01 to 0.98 mol / l LiPF 6 Contains:

[0034] According to one embodiment, the electrolyte composition of the present invention comprises: at least 0.05 mol / l, preferably at least 0.1 mol / l, preferentially at least 0.15, even more preferentially at least 0.2 mol / l, advantageously at least 0.25 mol / l and even more advantageously at least 0.3 mol / l LiFSI; and / or at least 0.05 mol / l, preferably at least 0.1 mol / l, preferentially at least 0.15, even more preferentially at least 0.2 mol / l, advantageously at least 0.25 mol / l and even more advantageously at least 0.3 mol / l of LiTDI; and / or at least 0.05 mol / l, preferably at least 0.1 mol / l, preferentially at least 0.15, even more preferentially at least 0.2 mol / l, advantageously at least 0.25 mol / l and even more advantageously at least 0.3 mol / l LiPF 6 Contains:

[0035] The LiFSI charging station is the most commonly used charging station. Moisture content: 0.01~0.99mol / l 、0.01~0.95mol / l、0.05~0.90mol / l、0.05~0.85mol / l、0.05~0.80mol / l、0. 05~0.75mol / l、0.05~0.70mol / l、0.05~0.65mol / l、0.05~0.50mol / l、0.05 ~0.45mol / l、0.1~0.99mol / l、0.1~0.95mol / l、0.1~0.90mol / l、0.1~0.85mo l / l、0.1~0.80mol / l、0.1~0.75mol / l、0.1~0.70mol / l、0.1~0.65mol / l、0. 1~0.50mol / l、0.1~0.45mol / l、0.15~0.99mol / l、0.15~0.95mol / l、0.15~0. 90mol / l、0.15~0.85mol / l、0.15~0.80mol / l、0.15~0.75mol / l、0.15~0.70 mol / l、0.15~0.65mol / l、0.15~0.50mol / l、0.15~0.45mol / l、0.20~0.99mol / l、0.20~0.95mol / l、0.20~0.90mol / l、0.20~0.85mol / l、0.20~0.80mol / l 、~0.20~0.75mol / l、0.20~0.70mol / l、0.20~0.65mol / l、0.20~0.50mol / l、0 .20~0.45mol / l、0.25~0.99mol / l、0.25~0.95mol / l、0.25~0.90mol / l、0.2 5~0.85mol / l、0.25~0.80mol / l、0.25~0.75mol / l、0.25~0.70mol / l、0.25~0 .65mol / l、0.25~0.50mol / l、0.25~0.45mol / l、0.30~0.99mol / l、0.30~0.9 5mol / l、0.30~0.90mol / l、0.30~0.85mol / l、0.30~0.80mol / l、0.30~0.75mo l / l、0.30~0.70mol / l、0.30~0.65mol / l、0.30~0.50mol / l、0.30~0.45mol / l 、0.35~0.99mol / l、0.35~0.95mol / l、0.35~0.90mol / l、0.35~0.85mol / l、0.35 to 0.80 mol / l, 0.35 to 0.75 mol / l, 0.35 to 0.70 mol / l, 0.35 to 0.65 mol / l, 0.35 to 0.50 mol / l, 0.35 to 0.45 mol / l, 0.40 to 0.99 mol / l, 0.40 to 0.95 mol / l, 0.40 to 0.90 mol / l, 0.40 to 0.85 mol / l, 0.40 to 0.80 mol / l, 0.40 to 0.75 mol / l, 0.40 to 0.75 mol / l, 0.40 to 0.70 mol / l, 0.40 to 0.65 mol / l, 0.40 to 0.60 mol / l, 0.40 to 0.55 mol / l, or 0.40 to 0.50 mol / l.

[0036] The LiTDI charging station is the most commonly used charging station. Moisture content: 0.01~0.99mol / l 、0.01~0.95mol / l、0.05~0.90mol / l、0.05~0.85mol / l、0.05~0.80mol / l、0. 05~0.75mol / l、0.05~0.70mol / l、0.05~0.65mol / l、0.05~0.50mol / l、0.05 ~0.45mol / l、0.1~0.99mol / l、0.1~0.95mol / l、0.1~0.90mol / l、0.1~0.85mo l / l、0.1~0.80mol / l、0.1~0.75mol / l、0.1~0.70mol / l、0.1~0.65mol / l、0. 1~0.50mol / l、0.1~0.45mol / l、0.15~0.99mol / l、0.15~0.95mol / l、0.15~0. 90mol / l、0.15~0.85mol / l、0.15~0.80mol / l、0.15~0.75mol / l、0.15~0.70 mol / l、0.15~0.65mol / l、0.15~0.50mol / l、0.15~0.45mol / l、0.20~0.99mol / l、0.20~0.95mol / l、0.20~0.90mol / l、0.20~0.85mol / l、0.20~0.80mol / l 、0.20~0.75mol / l、0.20~0.70mol / l、0.20~0.65mol / l、0.20~0.50mol / l、0. 20~0.45mol / l、0.25~0.99mol / l、0.25~0.95mol / l、0.25~0.90mol / l、0.25 ~0.85mol / l、0.25~0.80mol / l、0.25~0.75mol / l、0.25~0.70mol / l、0.25~0. 65mol / l、0.25~0.50mol / l、0.25~0.45mol / l、0.30~0.99mol / l、0.30~0.95 mol / l、0.30~0.90mol / l、0.30~0.85mol / l、0.30~0.80mol / l、0.30~0.75mol / l、0.30~0.70mol / l、0.30~0.65mol / l、0.30~0.50mol / l、0.30~0.45mol / l 、0.35~0.99mol / l、0.35~0.95mol / l、0.35~0.90mol / l、0.35~0.85mol / l、0.35 to 0.80 mol / l, 0.35 to 0.75 mol / l, 0.35 to 0.70 mol / l, 0.35 to 0.65 mol / l, 0.35 to 0.50 mol / l, 0.35 to 0.45 mol / l, 0.40 to 0.99 mol / l, 0.40 to 0.95 mol / l, 0.40 to 0.90 mol / l, 0.40 to 0.85 mol / l, 0.40 to 0.80 mol / l, 0.40 to 0.75 mol / l, 0.40 to 0.75 mol / l, 0.40 to 0.70 mol / l, 0.40 to 0.65 mol / l, 0.40 to 0.60 mol / l, 0.40 to 0.55 mol / l, or 0.40 to 0.50 mol / l.

[0037] According to one embodiment, LiPF in the electrolyte composition 6The concentration of 0.01~0.99mol / l, 0.01~0.95~0.55mol / l / l. 90mol / l、0.05~0.85mol / l、0.05~0.80mol / l、0.05~0.75mol / l、0.05~0.70 mol / l、0.05~0.65mol / l、0.05~0.50mol / l、0.05~0.45mol / l、0.1~0.99mol / l、0.1~0.95mol / l、0.1~0.90mol / l、0.1~0.85mol / l、0.1~0.80mol / l、0.1~ 0.75mol / l、0.1~0.70mol / l、0.1~0.65mol / l、0.1~0.50mol / l、0.1~0.45mo l / l、0.15~0.99mol / l、0.15~0.95mol / l、0.15~0.90mol / l、0.15~0.85mol / l l、0.15~0.80mol / l、0.15~0.75mol / l、0.15~0.70mol / l、0.15~0.65mol / l、 0.15~0.50mol / l、0.15~0.45mol / l、0.20~0.99mol / l、0.20~0.95mol / l、0.2 0~0.90mol / l、0.20~0.85mol / l、0.20~0.80mol / l、0.20~0.75mol / l、0.20~ 0.70mol / l、0.20~0.65mol / l、0.20~0.50mol / l、0.20~0.45mol / l、0.25~0. 99mol / l、0.25~0.95mol / l、0.25~0.90mol / l、0.25~0.85mol / l、0.25~0.80 mol / l、0.25~0.75mol / l、0.25~0.70mol / l、0.25~0.65mol / l、0.25~0.50mol / l、0.25~0.45mol / l、0.30~0.99mol / l、0.30~0.95mol / l、0.30~0.90mol / l 、0.30~0.85mol / l、0.30~0.80mol / l、0.30~0.75mol / l、0.30~0.70mol / l、0. 30~0.65mol / l、0.30~0.50mol / l、0.30~0.45mol / l、0.35~0.99mol / l、0.35 ~0.95mol / l、0.35~0.90mol / l、0.35~0.85mol / l、0.35~0.80mol / l、0.35~0.75mol / l, 0.35~0.70mol / l, 0.35~0.65mol / l, 0.35~0.50mol / l, 0.35~0.45mol / l, 0.40~0.99mol / l, 0.40~0.95mol / l, 0.40~0.90mol / l, 0.40~0.85mol / l, 0.40~0.80mol / l, 0.40~0.75mol / l, 0.40~0.75mol / l, 0.40~0.70mol / l, 0.40~0.65mol / l, 0.40~0.60mol / l, 0.40~0.55mol / l, or 0.40~0.50mol / l. .

[0038] According to one embodiment, the electrolyte composition comprises: - LiFSI from 0.05 to 0.90 mol / l; - LiTDI from 0.05 to 0.90 mol / l; and - 0.05 to 0.90 mol / l LiPF 6 Contains:

[0039] According to one embodiment, the electrolyte composition comprises: - LiFSI from 0.2 to 0.90 mol / l; - LiTDI from 0.05 to 0.60 mol / l; and - 0.05 to 0.60 mol / l LiPF 6 Contains:

[0040] According to one embodiment, the electrolyte composition comprises: - 0.3-0.70 mol / l LiFSI; - LiTDI from 0.1 to 0.50 mol / l; and - 0.1 to 0.50 mol / l LiPF 6 Contains:

[0041] According to one embodiment, the electrolyte composition comprises: - 0.35-0.60 mol / l LiFSI; - LiTDI from 0.15 to 0.50 mol / l; and - 0.15~0.50mol / l LiPF 6 Contains:

[0042] According to one embodiment, the electrolyte composition comprises: - 0.35-0.50 mol / l LiFSI; - LiTDI from 0.20 to 0.40 mol / l; and - 0.20~0.40mol / l LiPF 6 Contains:

[0043] According to one embodiment, the electrolyte composition comprises: - 0.35-0.45 mol / l LiFSI; - LiTDI from 0.25 to 0.35 mol / l; and - 0.25~0.35mol / l LiPF 6 Contains:

[0044] According to one embodiment, the electrolyte composition comprises: - 0.40 mol / l LiFSI; - 0.30 mol / l LiTDI; and - 0.30 mol / l LiPF 6 Contains:

[0045] According to one embodiment, the electrolyte composition comprises: - 0.50 mol / l LiFSI; - 0.20 mol / l LiTDI; and - 0.30 mol / l LiPF 6 Contains:

[0046] According to one embodiment, the electrolyte composition comprises: - the molarity of LiFSI is equal to or greater than 0.30 mol / l, and / or - the molar concentration of LiTDI is equal to or greater than 0.40 mol / l, and / or - LiPF 6The molar concentration of is 0.50 mol / l or less It's like that.

[0047] According to one embodiment, the electrolyte composition has a molar concentration of LiFSI equal to or greater than the molar concentration of LiTDI, and / or LiPF 6 is such that the molar concentration of LiTDI is equal to or greater than the molar concentration of LiTDI.

[0048] According to one embodiment, the electrolyte composition comprises LiFSI / LiPF 6 The molar ratio of LiFSI / LiPF in the mixture is preferably from 1 / 1 to 10 / 1, more preferably from 1 / 1 to 5 / 1, and more preferably from 1 / 1 to 2 / 1. 6 The molar ratio is 4 / 3 or 5 / 3.

[0049] According to one embodiment, the electrolyte composition may contain a solvent or a mixture of solvents, such as two, three or four different solvents.

[0050] The solvent of the electrolyte composition can be a liquid solvent, optionally gelled with a polymer, or a polar polymer solvent, optionally plasticized with a liquid.

[0051] According to one embodiment, the solvent is an organic solvent, preferably an aprotic organic solvent. Preferably, the solvent is a polar organic solvent.

[0052] According to one embodiment, the solvent is selected from the group consisting of ethers, carbonates, esters, ketones, partially hydrogenated hydrocarbons, nitriles, amides, alcohols, sulfoxides, sulfolane, nitromethane, 1,3-dimethyl-2-imidazolidinone, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone, 3-methyl-2-oxazolidinone, and mixtures thereof.

[0053] The ethers may include linear or cyclic ethers such as dimethoxyethane (DME), methyl ethers of oligoethylene glycols having 2 to 5 oxyethylene units, dioxolane, dioxane, dibutyl ether, tetrahydrofuran, and mixtures thereof.

[0054] The ester may be a phosphate or sulfite, such as methyl formate, methyl acetate, methyl propionate, ethyl acetate, butyl acetate, γ-butyrolactone, or a mixture thereof.

[0055] Among the ketones, mention may in particular be made of cyclohexanone.

[0056] The alcohol may include, for example, ethyl alcohol or isopropyl alcohol.

[0057] Examples of nitriles include acetonitrile, pyruvonitrile, propionitrile, methoxypropionitrile, dimethylaminopropionitrile, butyronitrile, isobutyronitrile, valeronitrile, pivalonitrile, isovaleronitrile, glutaronitrile, methoxyglutaronitrile, 2-methylglutaronitrile, 3-methylglutaronitrile, adiponitrile, malononitrile, and mixtures thereof.

[0058] Examples of carbonates include cyclic carbonates such as ethylene carbonate (EC) (CAS: 96-49-1), propylene carbonate (PC) (CAS: 108-32-7), butylene carbonate (BC) (CAS: 4437-85-8), dimethyl carbonate (DMC) (CAS: 616-38-6), diethyl carbonate (DEC) (CAS: 105-58-8), methyl ethyl carbonate (EMC) (CAS: 623-53-0), diphenyl carbonate (CAS 102-09-0), methyl phenyl carbonate (CAS: 13509-27-8), dipropyl carbonate (DPC) (CAS: 623-96-1), methyl propyl carbonate (MPC) (CAS: 1333-41-1), ethyl propyl carbonate (EPC), vinylene carbonate (VC) (CAS: 872-36-6), fluoroethylene carbonate (FEC) (CAS: 114435-02-8), trifluoropropylene carbonate (CAS: 167951-80-6) or mixtures thereof.

[0059] Particularly preferred solvents are chosen from carbonates and mixtures thereof. Mention may in particular be made of the following mixtures: - Ethylene carbonate (EC) / propylene carbonate (PC) / dimethyl carbonate (DMC) in a weight ratio of 1 / 1 / 1; - Ethylene carbonate (EC) / propylene carbonate (PC) / diethyl carbonate (DEC) in a weight ratio of 1 / 1 / 1; - Ethylene carbonate (EC) / propylene carbonate (PC) / ethyl methyl carbonate (EMC) in a weight ratio of 1 / 1 / 1; - Ethylene carbonate (EC) / dimethyl carbonate (DMC) in a weight ratio of 1 / 1; - Ethylene carbonate (EC) / diethyl carbonate (DEC) in a weight ratio of 1 / 1; - Ethylene carbonate (EC) / ethyl methyl carbonate (EMC) in a weight ratio of 1 / 1; - Ethylene carbonate (EC) / dimethyl carbonate (DMC) in a weight ratio of 3 / 7 by volume; - Ethylene carbonate (EC) / diethyl carbonate (DEC) in a volume ratio of 3 / 7; - Ethylene carbonate (EC) / ethyl methyl carbonate (EMC) in a volume ratio of 3 / 7.

[0060] Preferably, the solvent for the electrolyte composition is ethylene carbonate (EC) / ethyl methyl carbonate (EMC) in a volume ratio of 3 / 7.

[0061] According to one embodiment, the electrolyte composition contains at least one electrolyte additive.

[0062] Preferably, the electrolytic additive is fluoroethylene carbonate (FEC), vinylene carbonate, 4-vinyl-1,3-dioxolan-2-one, pyridazine, vinylpyridazine, quinoline, vinylquinoline, butadiene, sebaconitrile, LiB(C 2 O 4 ) 2 , lithium nitrate, alkyl disulfides, fluorotoluene, 1,4-dimethoxytetrafluorotoluene, t-butylphenol, di-t-butylphenol, tris(pentafluorophenyl)borane, oximes, aliphatic epoxides, halogenated biphenyls, methacrylic acid, allyl ethyl carbonate, vinyl acetate, divinyl adipate, acrylonitrile, 2-vinylpyridine, maleic anhydride, methyl cinnamate, phosphonates, vinyl-containing silane compounds, 2-cyanofuran, and mixtures thereof, and the electrolytic additive is preferably fluoroethylene carbonate (FEC).

[0063] For example, the content of the electrolytic additive in the electrolyte composition is 0.01% by weight to 10% by weight, preferably 0.1% by weight to 4% by weight, based on the total weight of the electrolyte composition. In particular, the content of the electrolytic additive in the electrolyte composition is 2% by weight or less based on the total weight of the composition.

[0064] The content of the electrolytic additive in the electrolyte composition can be, for example, 0.01% by weight to 10% by weight, preferably 0.1% by weight to 4% by weight, based on the total weight of the solvent in the composition.

[0065] According to one embodiment, the electrolyte composition according to the present invention is selected from one of the following compositions: i) 0.40 mol / l LiFSI, 0.30 mol / l LiTDI, and 0.30 mol / l LiPF 6 , fluoroethylene carbonate as electrolytic additive (in particular with a content of not more than 2% by weight relative to the total weight of the solvent), a mixture of EC / EMC in a volume ratio of 3 / 7 as solvent; - ii) 0.50 mol / l LiFSI, 0.20 mol / l LiTDI, 0.30 mol / l LiPF 6 , fluoroethylene carbonate as electrolytic additive (in particular with a content of not more than 2% by weight relative to the total weight of the solvent), a mixture of EC / EMC in a volume ratio of 3 / 7 as solvent; - ii) 0.45 mol / l LiFSI, 0.20 mol / l LiTDI, 0.35 mol / l LiPF 6 , fluoroethylene carbonate as electrolytic additive (in particular with a content of not more than 2% by weight relative to the total weight of the solvent), a mixture of EC / EMC in a volume ratio of 3 / 7 as solvent; ii) 0.50 mol / l LiFSI, 0.10 mol / l LiTDI, and 0.40 mol / l LiPF 6 , fluoroethylene carbonate as electrolytic additive (in particular with a content of less than 2% by weight relative to the total weight of the solvent), a mixture of EC / EMC in a volume ratio of 3 / 7 as solvent.

[0066] According to one embodiment, the electrolyte composition according to the present invention is selected from one of the following compositions: i) 0.40 mol / l LiFSI, 0.30 mol / l LiTDI, and 0.30 mol / l LiPF 6 , fluoroethylene carbonate as electrolytic additive (in particular with a content of not more than 2% by weight relative to the total weight of the solvent), a mixture of EC / EMC in a volume ratio of 3 / 7 as solvent; - ii) 0.50 mol / l LiFSI, 0.20 mol / l LiTDI, 0.30 mol / l LiPF 6 , fluoroethylene carbonate as electrolytic additive (in particular with a content of not more than 2% by weight relative to the total weight of the solvent), a mixture of EC / EMC in a volume ratio of 3 / 7 as solvent; - ii) 0.45 mol / l LiFSI, 0.20 mol / l LiTDI, 0.35 mol / l LiPF 6 , fluoroethylene carbonate as electrolytic additive (in particular with a content of not more than 2% by weight relative to the total weight of the solvent), a mixture of EC / EMC in a volume ratio of 3 / 7 as solvent; ii) 0.50 mol / l LiFSI, 0.10 mol / l LiTDI, and 0.40 mol / l LiPF 6 , fluoroethylene carbonate as electrolytic additive (in particular with a content of less than 2% by weight relative to the total weight of the solvent), a mixture of EC / EMC in a volume ratio of 3 / 7 as solvent.

[0067] The electrolyte composition can be prepared by any means known to one skilled in the art, such as by dissolving, preferably with stirring, the salts in the appropriate proportions of solvents and / or additives.

[0068] The present patent application also relates to the use of the electrolyte composition as defined above in a battery, for example a lithium-ion battery, in particular at a temperature range between -30° C. and 65° C., preferentially between -25° C. and 60° C., preferably at a temperature above 25° C., preferably between 25° C. and 65° C., advantageously between 40° C. and 60° C. For example in mobile devices such as mobile phones, cameras, tablet or laptop computers, electric vehicles or renewable energy storage.

[0069] [Electrochemical cell] The present patent application also relates to an electrochemical cell comprising a negative electrode, a positive electrode, and a mixture of lithium salts as described above.

[0070] The present patent application also relates to an electrochemical cell comprising a negative electrode, a positive electrode, and an electrolyte composition as defined above interposed between the negative and positive electrodes. The electrochemical cell may also comprise a separator impregnated with the electrolyte composition as defined above.

[0071] The present invention also relates to a battery comprising at least one electrochemical cell as described above. When a battery comprises several electrochemical cells according to the invention, said cells can be assembled in series and / or in parallel.

[0072] In the context of the present invention, negative electrode is understood to mean the electrode that acts as an anode when the battery produces an electric current (i.e. when it is in the process of discharging) and that acts as a cathode when the battery is in the process of charging.

[0073] The negative electrode typically comprises an electrochemically active material, an optional electronically conductive material, and an optional binder.

[0074] In the context of the present invention, "electrochemically active material" is understood to mean a material capable of reversibly inserting ions.

[0075] In the context of the present invention, "electronically conductive material" is understood to mean a material capable of conducting electrons.

[0076] According to one embodiment, the negative electrode of the electrochemical cell is made of a material selected from the group consisting of graphite, lithium, lithium alloys, Li 4 Ti 5 O 12 or TiO 2 The lithium tin oxide may be one of the types of lithium titanate, silicon or lithium / silicon alloy, tin oxide, lithium intermetallic compounds or mixtures thereof.

[0077] The negative electrode may contain lithium; the latter may then consist of a film of metallic lithium or an alloy containing lithium. An example of a negative electrode may include an active lithium film prepared by winding a strip of lithium between rollers.

[0078] In the context of the present invention, positive electrode is understood to mean the electrode that acts as a cathode when the battery produces an electric current (i.e. when it is in the process of discharging) and as an anode when the battery is in the process of charging.

[0079] The positive electrode typically comprises an electrochemically active material, an optional electronically conductive material, and an optional binder.

[0080] In another embodiment, the positive electrode of the electrochemical cell is manganese dioxide (MnO 2 ), iron oxide, copper oxide, nickel oxide, lithium / manganese composite oxide (e.g. Li x Mn 2 O 4 Or Li x MnO 2 ), lithium / nickel composite oxides (e.g. Li x NiO 2 ), lithium / cobalt composite oxides (e.g. Li x Chief of Staff 2 ), lithium / nickel / cobalt composite oxides (e.g. LiNi 1-y Co y O 2 ), lithium / nickel / cobalt / manganese composite oxide (e.g., LiNi x Mn y Co z O 2 ), lithium-rich lithium / nickel / cobalt / manganese composite oxides (e.g. Li 1+x (NiMnCo) 1-x O 2 ), lithium / transition metal composite oxides, lithium / manganese / nickel composite oxides with spinel structure (e.g. Li x Mn 2-y Ni y O 4 ), lithium / phosphate oxides with olivine structure (e.g. Li x FePO 4 , Li x Fe 1-y Mn y PO 4Or Li x CoPO 4 ), iron sulfate, vanadium oxide, and mixtures thereof.

[0081] Preferably, the positive electrode is LiCoO 2 , LiFePO 4 (LFP), LiMn x Co y Ni z O 2 (NMC, x+y+z=1), LiFePO 4 F, LiFeSO 4 F, LiNiCoAlO 2 and mixtures thereof.

[0082] The material of the positive electrode may also include, in addition to the electrochemically active material, an electronically conductive material such as a carbon source, including, for example, carbon black, Ketjen® carbon, Shawinigan carbon, graphite, graphene, carbon nanotubes, carbon fibers (such as vapor grown carbon fibers (VGCF)), non-powdered carbon obtained by carbonization of an organic precursor, or a combination of two or more thereof. Other additives, such as lithium salts or inorganic particles of ceramic or glass type, or other compatible active substances (e.g., sulfur), may also be present in the material of the positive electrode.

[0083] The material of the positive electrode may also include a binder. Non-limiting examples of binders include linear, branched and / or crosslinked polyether polymer binders (e.g., polymers based on poly(ethylene oxide) (PEO), or poly(propylene oxide) (PPO), or mixtures of the two (or EO / PO copolymers), optionally including crosslinkable units), water-soluble binders (SBR (styrene / butadiene rubber), NBR (acrylonitrile / butadiene rubber), HNBR (hydrogenated NBR), CHR (epichlorohydrin rubber), ACM (acrylate rubber), etc.), or fluoropolymer type binders (PVDF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), etc.), and combinations thereof. Some binders, such as those that are soluble in water, may also contain additives such as CMC (carboxymethylcellulose).

[0084] The salt mixture according to the invention advantageously has a good ionic conductivity in solution.Furthermore, the salt mixture according to the invention advantageously makes it possible to improve the power performance quality of the battery, thereby also making it possible, for example, to recharge the battery more quickly or to provide the necessary power in case of an energy peak.

[0085] The salt mixtures according to the invention also advantageously make it possible to have good performance qualities, especially with respect to power, over a wide temperature range, for example under low temperature conditions or over a temperature range extending from about -25°C to about 60°C.

[0086] The salt mixtures of the present invention advantageously allow a good compromise between good ionic conductivity in solution, good service life, electrochemical stability, and power performance quality, particularly over a wide temperature range, such as from about -25°C to about 60°C.

[0087] In the context of the present invention, the terms "from x to y" or "from x to y" are understood to mean an interval including the limits x and y. For example, the range "from 1% to 98%" or the "range from 1% to 98%" includes in particular the values ​​1% and 98%.

[0088] All of the above-mentioned embodiments can be combined with each other.

[0089] The following examples illustrate the invention but do not limit it. EXAMPLES

[0090] [Abbreviation] EC: Ethylene carbonate EMC: Ethyl methyl carbonate (CAS623-53-0) FEC: Fluoroethylene carbonate

[0091] [Supplier] EC:BASF EMC:BASF FEC:BASF LiPF 6 :BASF

[0092] The LiFSI used is in particular obtained by the method described in application WO 2015 / 158979, while the LiTDI is obtained from the method described in application WO 2013 / 072591.

[0093] Example 1: Ionic conductivity measured by impedance spectroscopy Two electrolytes were prepared with the following compositions: Composition 1 (example of the invention): 0.40M LiFSI, 0.30M LiTDI and 0.30M LiPF 6 , 3 / 7 (volume ratio) EC / EMC solvent mixture, 2 wt% FEC (based on the total weight of the EC / EMC solvent mixture); Composition 2 (comparative example): 0.40M LiTFSI, 0.30M LiTDI and 0.30M LiPF 6 , a 3 / 7 (volume ratio) EC / EMC solvent mixture, and 2 wt % FEC (based on the total weight of the EC / EMC solvent mixture).

[0094] The compositions were prepared according to the following procedure: Composition 1: In a glass reactor, 39.60 g of ethylene carbonate (30 ml) is dissolved in 70 ml of ethyl methyl carbonate. After obtaining a homogeneous solution, 2.21 g of fluoroethylene carbonate is added. Then, 4.63 g of LiPF 6 7.60 g of LiFSI and 5.85 g of LiTDI are dissolved in the solution previously obtained.

[0095] Therefore, composition 1 is LiFSI, LiTDI, LiPF 6 , EC / EMC (3 / 7 volume ratio), FEC (2% by weight based on the weight of the 3 / 7 EC / EMC solvent by volume), the total content of LiFSI in composition 1 was 0.40 mol / l, the total content of LiTDI in composition 1 was 0.30 mol / l, and the LiPF 6 The total content is 0.30 mol / l.

[0096] Composition 2: In a glass reactor, 19.80 g of ethylene carbonate (15 ml) is dissolved in 35 ml of ethyl methyl carbonate. After obtaining a homogeneous solution, 1.10 g of fluoroethylene carbonate is added. Then, 2.31 g of LiPF 6 5.83 g of LiTFSI and 2.92 g of LiTDI are dissolved in the solution previously obtained.

[0097] A conductivity cell was then immersed in each solution and three impedance spectroscopy measurements were performed. These spectroscopy measurements are performed at 500 mHz to 100 kHz with an amplitude of 10 mV. The cell constant used is 1.12 and the ionic conductivity is calculated according to the following formula: TIFF0007641117000002.tif10161Here, R represents the resistance obtained by linear regression of the curve Im(Z) = f(Re(Z)). In the particular case where Im(Z) = 0, R is equal to the ordinate opposite the origin divided by the slope of the linear regression equation. TIFF0007641117000003.tif34170 Composition 1 advantageously has better ionic conductivity than composition 2.

[0098] Example 2: Output test A Ragone plot test was carried out using compositions 1 and 2 prepared in Example 1. Method: The method consists in increasing the discharge rate of the battery to observe the ability of the electrolyte to respond to the stress imposed by the electrical circuit. [System used] Cathode: LiNi 0.33 Mn 0.33 Co 0.33 O 2 (89%), carbon fiber VGCF (2.5%), carbon black (2.5%) and 6% PVDF binder Anode: Lithium metal

[0099] The current was varied from 2.7V to 4.2V and the discharges were carried out in the following sequence: C / 20, C / 10, C / 5, C / 2, C and 2C. Two C / 20 formation cycles are performed prior to the study to form all passivation layers.

[0100] [result] The observations are as follows: TIFF0007641117000004.tif50166

[0101] The results show that composition 1 advantageously allows for operation at higher power ratings than composition 2. These higher ratings are particularly desirable in commercial batteries for mobile devices that require ever more power, and for electric vehicles, which, due to their short operating radius, require rapid recharging, and therefore electrolytes that allow operation at higher ratings.

Claims

1. - 1 mol % to 98 mol % of lithium bis(fluorosulfonyl)imide; - 1 mol % to 98 mol % of lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and - 1 mol% to 98 mol% lithium hexafluorophosphate A mixture for an electrolyte composition comprising: A mixture wherein lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate and lithium 2-trifluoromethyl-4,5-dicyanoimidazolate salts account for 100% of all salts present in the mixture.

2. at least 5 mol % of lithium bis(fluorosulfonyl)imide; and / or at least 5 mol % of lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and / or at least 10 mol% lithium hexafluorophosphate The mixture of claim 1 , comprising:

3. The lithium bis(fluorosulfonyl)imide content is in the following mole percentages: 1% to 95%, 5% to 90%, 5% to 85%, 5% to 80%, 5% to 75%, 5% to 70%, 5% to 65%, 5% to 50%, 5% to 45%, 10% to 98%, 10% to 95%, 10% to 90%, 10% to 85%, 10% to 80%, 10% to 75%, 10% to 70%, 10% to 65%, 10% to 60%, 10% to 55%, 10% to 50%, 10% to 45 ...55%, 10% to 50%, 10% to 45%, 10% to 55%, 10% to 55%, 10% to 55%, 10% to 55%, 10% to 55%, 10% to 45%, 10% to 55%, 10% to 55%, 10% to 55%, 10 5% to 98%, 15% to 95%, 15% to 90%, 15% to 85%, 15% to 80%, 15% to 75%, 15% to 70%, 15% to 65%, 15% to 60%, 15% to 55%, 15% to 50%, 15% to 45%, 20% to 98%, 20% to 95%, 20% to 90%, 20% to 85%, 20% to 80%, 20% to 75%, 20% to 70%, 20% to 65%, 20% to 60%, 20% to 55%, 20% to 50%, 20% to 45%, 25% to 9 8%, 25% to 95%, 25% to 90%, 25% to 85%, 25% to 80%, 25% to 75%, 25% to 70%, 25% to 65%, 25% to 60%, 25% to 55%, 25% to 50%, 25% to 45%, 30% to 98%, 30% to 95%, 30% to 90%, 30% to 85%, 30% to 80%, 30% to 75%, 30% to 70%, 30% to 65%, 30% to 60%, 30% to 55%, 30% to 50%, 30% to 45%, 35% to 98%, 3 3. The mixture of claim 1 or 2, selected from one of: 5% to 95%, 35% to 90%, 35% to 85%, 35% to 80%, 35% to 75%, 35% to 70%, 35% to 65%, 35% to 60%, 35% to 55%, 35% to 50%, 40% to 98%, 40% to 95%, 40% to 90%, 40% to 85%, 40% to 80%, 40% to 75%, 40% to 70%, 40% to 65%, 40% to 60%, 40% to 55%, or 40% to 50%.

4. The lithium 2-trifluoromethyl-4,5-dicyanoimidazolate content is in the following mole percentages: 1% to 95%, 5% to 90%, 5% to 85%, 5% to 80%, 5% to 75%, 5% to 70%, 5% to 65%, 5% to 50%, 5% to 45%, 10% to 98%, 10% to 95%, 10% to 90%, 10% to 85%, 10% to 80%, 10% to 75%, 10% to 70%, 10% to 65%, 10% to 60%, 10% to 55%, 10% to 5 ... % to 45%, 15% to 98%, 15% to 95%, 15% to 90%, 15% to 85%, 15% to 80%, 15% to 75%, 15% to 70%, 15% to 65%, 15% to 60%, 15% to 55%, 15% to 50%, 15% to 45%, 20% to 98%, 20% to 95%, 20% to 90%, 20% to 85%, 20% to 80%, 20% to 75%, 20% to 70%, 20% to 65%, 20% to 60%, 20% to 55%, 20% to 50%, 20% to 45%, 25% ~98%, 25%~95%, 25%~90%, 25%~85%, 25%~80%, 25%~75%, 25%~70%, 25%~65%, 25%~60%, 25%~55%, 25%~50%, 25%~45%, 30%~98%, 30%~95%, 30%~90%, 30%~85%, 30%~80%, 30%~75%, 30%~70%, 30%~65%, 30%~60%, 30%~55%, 30%~50%, 30%~45%, 35%~98%, 35% 4. The mixture of any one of claims 1 to 3, selected from one of: up to 95%, 35% to 90%, 35% to 85%, 35% to 80%, 35% to 75%, 35% to 70%, 35% to 65%, 35% to 60%, 35% to 55%, 35% to 50%, 40% to 98%, 40% to 95%, 40% to 90%, 40% to 85%, 40% to 80%, 40% to 75%, 40% to 70%, 40% to 65%, 40% to 60%, 40% to 55%, or 40% to 50%.

5. The lithium hexafluorophosphate content is in the following mole percentages: 1% to 95%, 5% to 90%, 5% to 85%, 5% to 80%, 5% to 75%, 5% to 70%, 5% to 65%, 5% to 50%, 5% to 45%, 10% to 98%, 10% to 95%, 10% to 90%, 10% to 85%, 10% to 80%, 10% to 75%, 10% to 70%, 10% to 65%, 10% to 60%, 10% to 55%, 10% to 50%, 10% to 45%, 15% to 98%. ,15%-95%,15%-90%,15%-85%,15%-80%,15%-75%,15%-70%,15%-65%,15%-60%,15%-55%,15%-50%,15%-45%,20%-98%,20%-95%,20%-90%,20%-85%,20%-80%,20%-75%,20%-70%,20%-65%,20%-60%,20%-55%,20%-50%,20%-45%,25%-98%,25% ~95%, 25%~90%, 25%~85%, 25%~80%, 25%~75%, 25%~70%, 25%~65%, 25%~60%, 25%~55%, 25%~50%, 25%~45%, 30%~98%, 30%~95%, 30%~90%, 30%~85%, 30%~80%, 30%~75%, 30%~70%, 30%~65%, 30%~60%, 30%~55%, 30%~50%, 30%~45%, 35%~98%, 35%~95% 5. The mixture of claim 1 , wherein the concentration of the mixture is selected from one of: 35% to 90%, 35% to 85%, 35% to 80%, 35% to 75%, 35% to 70%, 35% to 65%, 35% to 60%, 35% to 55%, 35% to 50%, 40% to 98%, 40% to 95%, 40% to 90%, 40% to 85%, 40% to 80%, 40% to 75%, 40% to 70%, 40% to 65%, 40% to 60%, 40% to 55%, or 40% to 50%.

6. i) - 5 mol % to 90 mol % of lithium bis(fluorosulfonyl)imide; - 5 mol % to 90 mol % of lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and - 5 mol % to 90 mol % of lithium hexafluorophosphate; or ii) - 20 mol % to 90 mol % of lithium bis(fluorosulfonyl)imide; - 5 mol % to 60 mol % of lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and - 5 mol % to 60 mol % of lithium hexafluorophosphate; or iii) - 30 mol % to 70 mol % of lithium bis(fluorosulfonyl)imide; - 10 mol % to 50 mol % of lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and - 10 mol % to 50 mol % of lithium hexafluorophosphate; or iv) - 35 mol % to 60 mol % of lithium bis(fluorosulfonyl)imide; - 15 mol % to 50 mol % of lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and - 15 mol % to 50 mol % of lithium hexafluorophosphate; or v) - 35 mol % to 50 mol % of lithium bis(fluorosulfonyl)imide; - 20 mol % to 40 mol % of lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and - 20 mol % to 40 mol % of lithium hexafluorophosphate; or vi) - 35 mol % to 45 mol % of lithium bis(fluorosulfonyl)imide; - 25 mol % to 35 mol % of lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and - 25 mol % to 35 mol % of lithium hexafluorophosphate; or vii) 40 mol % of lithium bis(fluorosulfonyl)imide; 30 mol% of lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and 30 mol% lithium hexafluorophosphate; or viii) 50 mol % of lithium bis(fluorosulfonyl)imide; 20 mol% of lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and 30 mol% lithium hexafluorophosphate The mixture according to any one of claims 1 to 5, comprising:

7. 7. The mixture according to claim 1, wherein the molar ratio of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate is from 1 / 1 to 10 / 1.

8. 8. An electrolyte composition comprising a mixture of lithium salts according to any one of claims 1 to 7, at least one solvent and optionally at least one electrolytic additive, A composition wherein lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate and lithium 2-trifluoromethyl-4,5-dicyanoimidazolate salts account for 100% of all salts present in the composition.

9. 9. The composition according to claim 8, wherein the molar concentration of the mixture is less than or equal to 5 mol / l.

10. at least 0.05 mol / l of lithium bis(fluorosulfonyl)imide; and / or at least 0.05 mol / l of lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and / or - lithium hexafluorophosphate at least 0.05 mol / l The composition according to claim 8 or 9, comprising:

11. i) - 0.05 to 0.90 mol / l of lithium bis (fluorosulfonyl) imide; - 0.05 to 0.90 mol / l lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and - 0.05 to 0.90 mol / l lithium hexafluorophosphate; or ii) - 0.2 to 0.90 mol / l of lithium bis(fluorosulfonyl)imide; - 0.05 to 0.60 mol / l lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and - 0.05 to 0.60 mol / l lithium hexafluorophosphate or iii) - 0.3 to 0.70 mol / l of lithium bis (fluorosulfonyl) imide; - 0.1 to 0.50 mol / l lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and 0.1 to 0.50 mol / l lithium hexafluorophosphate or iv) 0.35 to 0.60 mol / l of lithium bis(fluorosulfonyl)imide; - 0.15 to 0.50 mol / l lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and 0.15 to 0.50 mol / l lithium hexafluorophosphate or v) 0.35 to 0.50 mol / l of lithium bis(fluorosulfonyl)imide; - 0.20 to 0.40 mol / l lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and 0.20 to 0.40 mol / l lithium hexafluorophosphate or vi) - 0.35 to 0.45 mol / l of lithium bis (fluorosulfonyl) imide; - 0.25 to 0.35 mol / l lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and - 0.25 to 0.35 mol / l lithium hexafluorophosphate or vii) 0.40 mol / l lithium bis(fluorosulfonyl)imide; 0.30 mol / l lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and 0.30 mol / l lithium hexafluorophosphate or viii) 0.50 mol / l lithium bis(fluorosulfonyl)imide; 0.20 mol / l lithium 2-trifluoromethyl-4,5-dicyanoimidazolate; and 0.30 mol / l lithium hexafluorophosphate The composition according to any one of claims 8 to 10, comprising:

12. 12. The composition of any one of claims 8 to 11, wherein the solvent is selected from the group consisting of ethers, carbonates, esters, ketones, partially hydrogenated hydrocarbons, nitriles, amides, alcohols, sulfoxides, sulfolane, nitromethane, 1,3-dimethyl-2-imidazolidinone, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone, 3-methyl-2-oxazolidinone, and mixtures thereof.

13. 13. The composition according to any one of claims 8 to 12, wherein the solvent is selected from carbonates and mixtures thereof.

14. The electrolytic additives are fluoroethylene carbonate, vinylene carbonate, 4-vinyl-1,3-dioxolan-2-one, pyridazine, vinylpyridazine, quinoline, vinylquinoline, butadiene, sebaconitrile, LiB(C ２ O ４ ) ２ , lithium nitrate, alkyl disulfides, fluorotoluenes, 1,4-dimethoxytetrafluorotoluene, t-butylphenol, di-t-butylphenol, tris(pentafluorophenyl)borane, oximes, aliphatic epoxides, halogenated biphenyls, methacrylic acid, allyl ethyl carbonate, vinyl acetate, divinyl adipate, acrylonitrile, 2-vinylpyridine, maleic anhydride, methyl cinnamate, phosphonates, vinyl-containing silane compounds, 2-cyanofurans, and mixtures thereof.

15. The composition is: i) 0.40 mol / l lithium bis(fluorosulfonyl)imide, 0.30 mol / l lithium 2-trifluoromethyl-4,5-dicyanoimidazolate, and 0.30 mol / l LiPF ６ , fluoroethylene carbonate as electrolytic additive, a mixture of ethylene carbonate / ethyl methyl carbonate in a volume ratio of 3 / 7 as solvent; ii) 0.50 mol / l lithium bis(fluorosulfonyl)imide, 0.20 mol / l lithium 2-trifluoromethyl-4,5-dicyanoimidazolate, and 0.30 mol / l LiPF ６ , fluoroethylene carbonate as electrolytic additive, a mixture of ethylene carbonate / ethyl methyl carbonate in a volume ratio of 3 / 7 as solvent; iii) 0.45 mol / l lithium bis(fluorosulfonyl)imide, 0.20 mol / l lithium 2-trifluoromethyl-4,5-dicyanoimidazolate, and 0.35 mol / l LiPF ６ , fluoroethylene carbonate as electrolytic additive, a mixture of ethylene carbonate / ethyl methyl carbonate in a volume ratio of 3 / 7 as solvent; iv) 0.50 mol / l lithium bis(fluorosulfonyl)imide, 0.10 mol / l lithium 2-trifluoromethyl-4,5-dicyanoimidazolate, and 0.40 mol / l LiPF ６ , fluoroethylene carbonate as an electrolytic additive, and a mixture of ethylene carbonate / ethyl methyl carbonate in a volume ratio of 3 / 7 as a solvent. The composition according to claim 8 , wherein the composition is selected from one of the following:

16. 16. Use of a mixture according to any one of claims 1 to 7 or an electrolyte composition according to any one of claims 8 to 15 in a lithium ion battery.

17. 16. An electrochemical cell comprising a negative electrode, a positive electrode, and an electrolyte composition according to any one of claims 8 to 15, or a mixture according to any one of claims 1 to 7, interposed between the negative electrode and the positive electrode.

18. 20. A battery comprising at least one electrochemical cell according to claim 17.

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