FR3098350A1 - Lithium bis (fluorosulfonyl) imide salt and its uses - Google Patents

Abstract

Lithium bis (fluorosulfonyl) imide salt and uses thereof The present invention relates to a lithium bis (fluorosulfonyl) imide salt, characterized in that, after dissolving in water to form an aqueous solution, said aqueous solution has a pH between 4 and 8, in particular at a temperature of 25 ° C, and its uses in Li-ion batteries. The present invention also relates to a lithium bis (fluorosulfonyl) imide salt, comprising an H + ion content of between 0.08 ppb and 0.80 ppm, between 0.08 ppb and 0.63 ppm or between 0.25 ppb and 2.53 ppb. No figure

Description

Lithium bis(fluorosulfonyl)imide salt and uses thereof

FIELD OF THE INVENTION

The present invention relates to a lithium bis(fluorosulfonyl)imide salt having a specific content of H ⁺ protons.

The present invention also relates to various uses of said lithium bis(fluorosulfonyl)imide salt.

The Li-ion battery market requires the development of higher power batteries. This involves increasing the nominal voltage of Li-ion batteries. To achieve the targeted voltages, high purity electrolytes are required.

In the specific field of Li-ion batteries, the salt currently most widely used is LiPF ₆ . This salt shows many disadvantages such as limited thermal stability, susceptibility to hydrolysis and therefore lower battery safety.

New sulfonylimide type lithium salts have recently been developed in an attempt to improve the performance of secondary batteries. We can cite LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) and LiFSI (lithium bis(fluorosulfonyl)imide). These salts exhibit little or no spontaneous decomposition, and are more stable with respect to hydrolysis than LiPF ₆ . However, LiTFSI has the disadvantage of being corrosive to aluminum current collectors.

However, there is a need for new salts with improved electronic performance and/or longer life in Li-ion batteries.

There is also a need for new salts that can be used at high load cut-off voltages.

DESCRIPTION OF THE INVENTION

The present invention relates to a lithium bis(fluorosulfonyl)imide salt, characterized in that, after dissolving in water to form an aqueous solution, said aqueous solution has a pH of between 4 and 8, in particular at a temperature of 25°C.

According to a preferred embodiment, the LiFSI salt is such that after dissolving in water to form an aqueous solution, said aqueous solution has a pH for example between 4.1 and 8, between 4.2 and 8 , between 4.3 and 8, between 4.4 and 8, between 4.5 and 8, between 4.6 and 8, between 4.7 and 8, between 4.8 and 8, between 4.9 and 8, between 5 and 8, between 5.1 and 8, between 5.2 and 8, between 5.3 and 8, between 5.4 and 8, between 5.5 and 8, between 5.6 and 8, between 5, 7 and 8, between 5.8 and 8, between 5.9 and 8, between 6 and 8, between 6.1 and 8, between 6.2 and 8, between 6.3 and 8, between 6.4 and 8 , between 6.5 and 8, between 6.6 and 8, between 6.7 and 8, between 6.8 and 8, between 6.9 and 8, between 7 and 8, between 4 and 7.5, between 4 ,1 and 7.5, between 4.2 and 7.5, between 4.3 and 7.5, between 4.4 and 7.5, between 4.5 and 7.5, between 4.6 and 7, 5, between 4.7 and 7.5, between 4.8 and 7.5, between 4.9 and 7.5, between 5 and 7.5, between 5.1 and 7.5, between 5.2 and 7.5, between 5.3 and 7.5, between 5.4 and 7.5, between 5.5 and 7.5, between 5.6 and 7.5, between 5.7 and 7.5, between 5.8 and 7.5, between 5.9 and 7.5, between 6 and 7.5, between 6.1 and 7.5, between 6.2 and 7.5, between 6.3 and 7.5, between 6.4 and 7, 5, or between 6.5 and 7.5. Preferably, the LiFSI salt according to the invention is such that after dissolution in water to form an aqueous solution, said aqueous solution has a pH of between 6 and 8, preferably between 6.5 and 8, and in particular between 6.5 and 7.5.

In the context of the invention, the terms "lithium salt of bis(fluorosulfonyl)imide", "lithium bis(sulfonyl)imide", "LiFSI", "LiN(FSO ₂ ) ₂ ", " bis(sulfonyl)imide lithium”, or “lithium bis(fluorosulfonyl)imide”.

Typically, the pH is defined as the negative logarithm of the activity of the hydrogen ion, according to the following formula:

The pH of a solution can be measured by any method known to those skilled in the art. For example, the pH can be measured using a glass electrode, the potential of which can vary according to the concentration of hydrogen ions according to the Nernst equation. This potential can be measured against a reference electrode using a high impedance potentiometer, commonly known as a pH meter. As a pH meter, one can for example use the pHM210 model from the Radiometer brand.

The pH of the LiFSI solution can be measured using a pH meter, in particular previously calibrated using three buffer solutions (pH=4.0, 7.0 and 10.0). The LiFSI salt can be dissolved in water (said water preferably having a pH of 7.45 ± 0.5), to obtain a mass concentration of LiFSI of 0.125 g/mL. The aqueous solution can be stirred during the pH measurement.

According to one embodiment, the LiFSI concentration in the aqueous solution according to the invention is between 0.050 and 0.250 g/mL, preferably between 0.080 and 0.200 g/mL, preferentially between 0.1 and 0.2, in particular the concentration is 0.125 g/mL.

According to one embodiment, the aforementioned lithium bis(fluorosulfonyl)imide salt comprises an H ⁺ ion content of between 0.08 ppb and 0.80 ppm, between 0.08 ppb and 0.63 ppm, between 0, 08 ppb to 0.50 ppm, 0.08 ppb to 0.40 ppm, 0.08 ppb to 0.32 ppm, 0.08 ppb to 0.25 ppm, 0.08 ppb to 0.20 ppm, between 0.08 ppb and 0.16 ppm, between 0.08 ppb and 0.13 ppm, between 0.08 ppb and 0.10 ppm, between 0.08 ppb and 0.08 ppm, between 0.08 ppb and 0.06 ppm, between 0.08 ppb and 0.05 ppm, between 0.08 ppb and 0.04 ppm, between 0.08 ppb and 0.032 ppm, between 0.08 ppb and 0.025 ppm, between 0, 08 ppb and 0.020 ppm, between 0.08 ppb and 0.016 ppm, between 0.08 ppb and 0.013 ppm, between 0.08 ppb and 10 ppb, between 0.08 ppb and 8 ppb, between 0.08 ppb and 6, 35 ppb, 0.08 ppb to 5.05 ppb, 0.08 ppb to 4 ppb, 0.08 ppb to 3.18 ppb, 0.08 ppb to 2.53 ppb, 0.08 ppb and 2.01 ppb, between 0.08 ppb and 1.59 ppb, between 0.08 ppb and 1.27 ppb, between 0.08 ppb and 1.01 ppb, between 0.25 ppb and 0.8 ppm, between 0.25 ppb to 0.63 ppm, 0.25 ppb to 0.50 ppm, 0.25 ppb to 0.40 ppm, 0.25 ppb to 0.32 ppm, 0.25 ppb to 0 .25 ppm, between 0.25 ppb and 0.20 ppm, between 0.25 ppb and 0.16 ppm, between 0.25 ppb and 0.13 ppm, between 0.25 ppb and 0.10 ppm, between 0 .25 ppb to 0.08 ppm, 0.25 ppb to 0.06 ppm, 0.25 ppb to 0.05 ppm, 0.25 ppb to 0.04 ppm, 0.25 ppb to 0.032 ppm , between 0.25 ppb and 0.025 ppm, between 0.25 ppb and 0.020 ppm, between 0.25 ppb and 0.016 ppm, between 0.25 ppb and 0.013 ppm, between 0.25 ppb and 10 ppb, between 0.25 ppb and 8 ppb, between 0.25 ppb and 6.35 ppb, between 0.25 ppb and 5.05 ppb, between 0.25 ppb and 4 ppb, between 0.25 ppb and 3.18 ppb, or between 0 .25 ppb and 2.53 ppb.

In the context of the invention, the term “ppm” corresponds to “part per million” and is understood to mean ppm by weight.

In the context of the invention, the term “ppb” corresponds to “part per billion”, and is understood to mean ppb by weight.

In the context of the invention, the term “salt having a content of H ⁺ ions equal to 8 ppm by weight” is understood to mean, for example, a salt having a content of H ⁺ ions equal to 8 ppm by weight relative to the total weight. of said salt.

The present invention also relates to a lithium bis(fluorosulfonyl)imide salt, comprising an H ⁺ ion content of between 0.08 ppb and 0.80 ppm, 0.08 ppb and 0.63 ppm, between 0.08 ppb and 0.50 ppm, between 0.08 ppb and 0.40 ppm, between 0.08 ppb and 0.32 ppm, between 0.08 ppb and 0.25 ppm, between 0.08 ppb and 0.20 ppm, between 0.08 ppb and 0.16 ppm, between 0.08 ppb and 0.13 ppm, between 0.08 ppb and 0.10 ppm, between 0.08 ppb and 0.08 ppm, between 0.08 ppb and 0.06 ppm, between 0.08 ppb and 0.05 ppm, between 0.08 ppb and 0.04 ppm, between 0.08 ppb and 0.032 ppm, between 0.08 ppb and 0.025 ppm, between 0.08 ppb and 0.020 ppm, between 0.08 ppb and 0.016 ppm, between 0.08 ppb and 0.013 ppm, between 0.08 ppb and 10 ppb, between 0.08 ppb and 8 ppb, between 0.08 ppb and 6.35 ppb , between 0.08 ppb and 5.05 ppb, between 0.08 ppb and 4 ppb, between 0.08 ppb and 3.18 ppb, between 0.08 ppb and 2.53 ppb, between 0.08 ppb and 2 .01 ppb, between 0.08 ppb and 1.59 ppb, between 0.08 ppb and 1.27 ppb, between 0.08 ppb and 1.01 ppb, between 0.25 ppb and 0.8 ppm, between 0 .25 ppb and 0.63 ppm, between 0.25 ppb and 0.50 ppm, between 0.25 ppb and 0.40 ppm, between 0.25 ppb and 0.32 ppm, between 0.25 ppb and 0.25 ppm , between 0.25 ppb and 0.20 ppm, between 0.25 ppb and 0.16 ppm, between 0.25 ppb and 0.13 ppm, between 0.25 ppb and 0.10 ppm, between 0.25 ppb and 0.08 ppm, between 0.25 ppb and 0.06 ppm, between 0.25 ppb and 0.05 ppm, between 0.25 ppb and 0.04 ppm, between 0.25 ppb and 0.032 ppm, between 0 .25 ppb to 0.025 ppm, 0.25 ppb to 0.020 ppm, 0.25 ppb to 0.016 ppm, 0.25 ppb to 0.013 ppm, 0.25 ppb to 10 ppb, 0.25 ppb to 8 ppb, between 0.25 ppb and 6.35 ppb, between 0.25 ppb and 5.05 ppb, between 0.25 ppb and 4 ppb, between 0.25 ppb and 3.18 ppb, or between 0.25 ppb and 2.53 ppb.

The determination of the H ⁺ proton content in the lithium bis(fluorosulfonyl)imide salt is preferably carried out by pH-metry, in particular according to the method mentioned above.

The applicant has discovered that the use of the LiFSI salt according to the invention in a Li-ion battery electrolyte advantageously makes it possible to have a low residual current at a charging cut-off voltage of, for example, 4.2 V or 4 ,4V. This residual current translates the parasitic reactions which take place in a Li-ion battery during its use. These parasitic reactions consume electrons and therefore reduce the autonomy of Li-ion batteries during their use. Moreover, these parasitic reactions also have a strong impact on battery safety because such reactions can create chain reactions that can cause the Li-ion battery to runaway and explode.

Thus, the use of the LiFSI salt according to the invention in a Li-ion battery electrolyte advantageously makes it possible to improve the Li-ion battery lifetime and/or the electronic performance of a Li-ion battery, and/or the safety of said battery, in particular at a high charging cut-off voltage such as for example at 4.4V.

The use of the LiFSI salt according to the invention in a Li-ion battery advantageously makes it possible to achieve a high charging cut-off voltage, in particular greater than or equal to 4.4V.

In the context of the invention, and unless otherwise stated, the term "cut-off voltage" means the high voltage limit of a battery considered to be fully charged. The cut-off voltage is usually chosen in order to obtain the maximum capacity of the battery.

The present invention also relates to the use of lithium bis(fluorosulfonyl)imide salt in a Li-ion battery.

The present invention also relates to the use of lithium bis(fluorosulfonyl)imide salt in a Li-ion battery operating at a charge cut-off voltage greater than or equal to 4.2V, preferably greater than or equal to 4.4V.

The present invention also relates to the use of lithium bis(fluorosulfonyl)imide salt in an electrolyte, in particular in a Li-ion battery electrolyte.

The present invention also relates to an electrolyte composition comprising the lithium bis(fluorosulfonyl)imide salt as defined according to the invention, and an organic solvent.

Examples of organic solvents include ethers such as ethylene glycol dimethyl ether (1,2-dimethoxyethane), ethylene glycol diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 2,6-dimethyltetrahydrofuran, tetrahydropyran, a crown ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,4-dioxane and 1,3-dioxolane; carbonic acid esters such as dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, diphenyl carbonate and methyl phenyl carbonate; cyclic carbonate esters such as ethylene carbonate, propylene carbonate, ethylene 2,3-dimethylcarbonate, butylene carbonate, vinylene carbonate and ethylene 2-vinylcarbonate; aliphatic carboxylic acid esters such as methyl formate, methyl acetate, methyl propionate, ethyl acetate, propyl acetate, butyl acetate and amyl acetate ; aromatic carboxylic acid esters such as methyl benzoate and ethyl benzoate; carboxylic acid esters such as γ-butyrolactone, γ-valerolactone and 5-valerolactone; phosphoric acid esters such as trimethyl phosphate, ethyl dimethyl phosphate, diethyl methyl phosphate and triethyl phosphate; nitriles such as acetonitrile, propionitrile, methoxypropionitrile, glutaronitrile, adiponitrile, 2-methylglutaronitrile, valeronitrile, butyronitrile and isobutyronitrile; amides such as N-methylformamide, N-ethylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidinone, N-methylpyrrolidone and N-vinylpyrrolidone; sulfur compounds such as dimethylsulfone, ethylmethylsulfone, diethylsulfone, sulfolane, 3-methylsulfolane and 2,4-dimethylsulfolane; alcohols such as ethylene glycol, propylene glycol, ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; sulfoxides such as dimethyl sulfoxide, methyl ethyl sulfoxide and diethyl sulfoxide; aromatic nitriles such as benzonitrile and tolunitrile; nitromethane; 1,3-dimethyl-2-imidazolidinone; 1,3-dimethyl-3,4,5,6-tetrahydro-2(1,H)-pyrimidinone; 3-methyl-2-oxazolidinone. These solvents can be used individually or in combinations.

Carbonic acid esters, aliphatic carboxylic acid esters, carboxylic acid esters and ethers are preferred, and carbonic acid esters are even more preferred. In particular, the organic solvent is the ethylene carbonate/ethyl methyl carbonate mixture, in particular in a volume ratio of 3/7.

The concentration of LiFSI salt according to the invention can vary between 0.1% and 15%, preferably between 1% and 10% by weight relative to the total weight of the electrolyte composition.

According to one embodiment, the electrolyte composition may comprise one or more additives. Mention may be made, for example, of fluoroethylene carbonate, vinylene carbonate, ionic liquids, anhydrides such as for example succinic anhydride, and mixtures thereof.

The content of additives in the electrolyte composition according to the invention can vary between 0.1 and 10%, preferably between 1% and 5% by weight relative to the total weight of the electrolyte composition.

The present invention also relates to the use of said lithium bis(fluorosulfonyl)imide salt or of the electrolyte composition containing it, in Li-ion batteries, in particular in Li-ion batteries of mobile devices, for example mobile phones or laptop computers, electric vehicles, renewable energy storage, for example photovoltaics or wind power.

The present application relates to the use of the lithium bis(fluorosulfonyl)imide salt according to the invention to improve the life of a Li-ion battery and/or the electronic performance of a Li-ion battery and/or the safety of said battery, in particular at a high charging cut-off voltage such as for example at 4.4V.

Preferably, the invention relates to the use of the lithium bis(fluorosulfonyl)imide salt according to the invention to reduce the residual current during the application of a load cut-off voltage, for example of 4.2 volts or 4.4 volts.

The lithium bis(fluorosulfonyl)imide salt according to the invention, having a specific content of H ⁺ ions or a specific pH in aqueous solution, can be obtained by implementing a step of adjusting the pH of a lithium bis(fluorosulfonyl)imide salt in water initially prepared by any process known to the state of the art.

The present invention also relates to a process for the preparation of the aforementioned lithium bis(fluorosulfonyl)imide salt, comprising:

- i) a step of preparing a lithium bis(fluorosulfonyl)imide salt; And

- ii) a pH adjustment step,

to obtain a lithium bis(fluorosulfonyl)imide salt forming, after dissolving in water, an aqueous solution having a pH of between 4 and 8, in particular at a temperature of 25°C.

The present invention also relates to a process for the preparation of the aforementioned lithium bis(fluorosulfonyl)imide salt, comprising:

- i) a step of preparing a lithium bis(fluorosulfonyl)imide salt; And

- ii) a pH adjustment step,

to obtain a lithium bis(fluorosulfonyl)imide salt, comprising an H ⁺ ion content of between 0.08 ppb and 0.80 ppm.

The pH adjustment step may consist of one or more washes with water, in particular deionized water, or the addition of basic aqueous solution.

The preparation process may comprise subsequent stages of extraction of the lithium bis(fluorosulfonyl)imide salt obtained at the end of stage ii) in the organic phase (for example by adding an organic solvent such as acetate of butyl), concentration for example at a temperature below 60°C, crystallization, etc.

All the embodiments described above can be combined with each other.

The following examples illustrate the invention, without however limiting it.

EXAMPLES

Chronoamperometry tests were carried out. For this, CR2032 button cells were manufactured equipped with a 20 mm diameter aluminum foil as the working electrode, an 8 mm diameter lithium metal pellet as the reference electrode and a fiberglass separator. diameter 18 mm soaked with 12 drops (0.6 mL) of a 1 mol/L LiFSI solution in a mixture of solvent composed of ethylene carbonate and ethyl methyl carbonate (CAS = 623-53-0) in a 3/7 volume ratio. Then a voltage was applied to the terminals of the button cell and the current generated was measured and recorded.

Example 1 : Chronoamperometry study at a load cut-off voltage of 4.2 volts

Chronoamperometry measurements were performed in a system with an aluminum electrode as the working electrode and lithium metal as the reference electrode.

pH measurement : The pH of the LiFSI solutions is measured using a pH meter (model pHM210 from the Radiometer brand) previously calibrated using three buffer solutions (pH=4.0, 7.0 and 10.0). The LiFSI salt was dissolved in a quantity of water (having a pH of 7.45±0.5), to obtain a mass concentration of LiFSI of 0.125 g/mL. The aqueous solution is stirred during the pH measurement.

The LiFSI salt of solution No. 3 was obtained according to the method described in Abouimrane et al. "Liquid Electrolyte based on lithium bis-fluorosulfonyl imide salt: Al corrosion studies and lithium ion battery investigation", Journal of Power Sources 189 (2009), p. 693-696 (paragraph 3. Results). The LiFSI salts of solutions No. 1 and No. 2 were obtained from LiFSI salt prepared according to the method described in the article by Abouimrane et al. above, followed by a pH adjustment step. The following solutions 1 to 3 were prepared, and their pH was measured according to the method mentioned above:

LiFSI Solution #1 #2 #3 pH (at 25°C) 7.29 6.79 2.27

Preparation of electrolytes :

To carry out the chronoamperometry tests, various Li-ion battery electrolytes from LiFSI solutions No. 1 to No. 3 (see table above) were prepared.

Three electrolytes were prepared by dissolving a LiFSI salt (No. 1 to No. 3) in a solvent mixture composed of ethylene carbonate and methyl ethyl carbonate (CAS = 623-53-0) in a 3/7 volume ratio, to obtain solutions with a content of 1 mol/L of LiFSI:

Electrolyte No. 1E
(invention) No. 2E
(invention) #3E
(comparative) LiFSI Solution #1 #2 #3 pH (at 25°C) 7.29 6.79 2.27

Chronoamperometry :

The chronoamperometry test was carried out at 25°C, by applying a constant load cut-off voltage (4.2 volts) and the current obtained was observed. After 5 hours, the value of the residual current was measured and transcribed in the following table. This residual current is the indicator of the side reactions that can occur during the operation of a Li-ion battery.

pH 2.27 7.29 I at 4.2V
(t=5H) 31 14.4

The results show that electrolyte No. 3E (LiFSI: pH = 2.27) leads to a residual current twice as high as electrolyte No. 1E (LiFSI: pH = 7.29), after 5 hours of operation (i.e. after the formation of the passivation layers on the aluminum electrode). However, this current is directly linked to the life of the Li-ion battery. Indeed, each electron consumed in a parasitic reaction no longer participates in the capacity or autonomy of the battery.

Thus, the use of a LiFSI salt according to the invention (having a pH of 7.29 after dissolution in water), leads to a lower residual current, and therefore to a better duration of life of the Li-ion battery, than with a LiFSI salt having a pH of 2.27 after dissolving in water.

Example 2 : Chronoamperometry study at 4.4 volts

An experiment similar to Example 2 was performed but at a load cut-off voltage of 4.4 V.

After 5 hours, the value of the residual current was measured and transcribed in the following table.

pH 2.27 6.79 7.29 I at 4.4V
(t=5H) 401 203 130

The results demonstrate that electrolyte No. 3E (LiFSI: pH = 2.27) leads to a residual current 3 higher than electrolyte No. 1E (LiFSI: pH = 7.29), after 5 hours of operation (i.e. after the formation of the passivation layers on the aluminum electrode).

Thus, the use of a LiFSI salt according to the invention (having a pH of 7.29 after dissolution in water), leads to a lower residual current, and therefore to a better duration of life of the Li-ion battery, than with a LiFSI salt having a pH of 2.27.

Similar results are obtained with a LiFSI having a pH of 6.79 after dissolution in water compared to that with a pH of 2.27.

Claims (9)

Lithium bis(fluorosulfonyl)imide salt, characterized in that, after dissolving in water to form an aqueous solution, said aqueous solution has a pH of between 4 and 8, in particular at a temperature of 25°C . Lithium bis(fluorosulfonyl)imide salt according to Claim 1, characterized in that, after dissolving in water to form an aqueous solution, the said aqueous solution has a pH of between 4.1 and 8, between 4, 2 and 8, between 4.3 and 8, between 4.4 and 8, between 4.5 and 8, between 4.6 and 8, between 4.7 and 8, between 4.8 and 8, between 4.9 and 8, between 5 and 8, between 5.1 and 8, between 5.2 and 8, between 5.3 and 8, between 5.4 and 8, between 5.5 and 8, between 5.6 and 8, between 5.7 and 8, between 5.8 and 8, between 5.9 and 8, between 6 and 8, between 6.1 and 8, between 6.2 and 8, between 6.3 and 8, between 6, 4 and 8, between 6.5 and 8, between 6.6 and 8, between 6.7 and 8, between 6.8 and 8, between 6.9 and 8, between 7 and 8, between 4 and 7.5 , between 4.1 and 7.5, between 4.2 and 7.5, between 4.3 and 7.5, between 4.4 and 7.5, between 4.5 and 7.5, between 4.6 and 7.5, between 4.7 and 7.5, between 4.8 and 7.5, between 4.9 and 7.5, between 5 and 7.5, between 5.1 and 7.5, between 5 ,2 and 7.5, between 5.3 and 7.5, between 5.4 and 7.5, between 5.5 and 7.5, between 5.6 and 7.5, between 5.7 and 7, 5, between 5.8 and 7.5, between 5.9 and 7.5, between 6 and 7.5, between 6.1 and 7.5, between 6.2 and 7.5, between 6.3 and 7, 5, between 6.4 and 7.5, or between 6.5 and 7.5. Lithium bis(fluorosulfonyl)imide salt according to any one of Claims 1 or 2, characterized in that the concentration of the said salt in the aqueous solution is between 0.050 and 0.250 g/mL, preferably between 0.080 and 0.200 g/ mL, preferably between 0.1 and 0.2, in particular the concentration is 0.125 g/mL. Lithium bis(fluorosulfonyl)imide salt according to any one of Claims 1 to 3, characterized in that it comprises an H ⁺ ion content of between 0.08 ppb and 0.80 ppm, between 0.08 ppb and 0.63 ppm, between 0.08 ppb and 0.50 ppm, between 0.08 ppb and 0.40 ppm, between 0.08 ppb and 0.32 ppm, between 0.08 ppb and 0.25 ppm , between 0.08 ppb and 0.20 ppm, between 0.08 ppb and 0.16 ppm, between 0.08 ppb and 0.13 ppm, between 0.08 ppb and 0.10 ppm, between 0.08 ppb and 0.08 ppm, between 0.08 ppb and 0.06 ppm, between 0.08 ppb and 0.05 ppm, between 0.08 ppb and 0.04 ppm, between 0.08 ppb and 0.032 ppm, between 0 .08 ppb to 0.025 ppm, 0.08 ppb to 0.020 ppm, 0.08 ppb to 0.016 ppm, 0.08 ppb to 0.013 ppm, 0.08 ppb to 10 ppb, 0.08 ppb to 8 ppb, between 0.08 ppb and 6.35 ppb, between 0.08 ppb and 5.05 ppb, between 0.08 ppb and 4 ppb, between 0.08 ppb and 3.18 ppb, between 0.08 ppb and 2.53 ppb, between 0.08 ppb and 2.01 ppb, between 0.08 ppb and 1.59 ppb, between 0.08 ppb and 1.27 ppb, between 0.08 ppb and 1.01 ppb, in between 0.25 ppb and 0.8 ppm, between 0.25 ppb and 0.63 ppm, between 0.25 ppb and 0.50 ppm, between 0.25 ppb and 0.40 ppm, between 0.25 ppb and 0.32 ppm, between 0.25 ppb and 0.25 ppm, between 0.25 ppb and 0.20 ppm, between 0.25 ppb and 0.16 ppm, between 0.25 ppb and 0.13 ppm, between 0.25 ppb to 0.10 ppm, 0.25 ppb to 0.08 ppm, 0.25 ppb to 0.06 ppm, 0.25 ppb to 0.05 ppm, 0.25 ppb to 0 .04 ppm, between 0.25 ppb and 0.032 ppm, between 0.25 ppb and 0.025 ppm, between 0.25 ppb and 0.020 ppm, between 0.25 ppb and 0.016 ppm, between 0.25 ppb and 0.013 ppm, between 0.25 ppb to 10 ppb, 0.25 ppb to 8 ppb, 0.25 ppb to 6.35 ppb, 0.25 ppb to 5.05 ppb, 0.25 ppb to 4 ppb, 0 .25 ppb and 3.18 ppb, or between 0.25 ppb and 2.53 ppb. Bis(fluorosulfonyl)imide salt of lithium comprising an H ⁺ ion content comprised
between 0.08 ppb and 0.80 ppm, between 0.08 ppb and 0.63 ppm, between 0.08 ppb and 0.50 ppm, between 0.08 ppb and 0.40 ppm, between 0.08 ppb and 0.32 ppm, between 0.08 ppb and 0.25 ppm, between 0.08 ppb and 0.20 ppm, between 0.08 ppb and 0.16 ppm, between 0.08 ppb and 0.13 ppm, between 0.08 ppb to 0.10 ppm, 0.08 ppb to 0.08 ppm, 0.08 ppb to 0.06 ppm, 0.08 ppb to 0.05 ppm, 0.08 ppb to 0 .04 ppm, between 0.08 ppb and 0.032 ppm, between 0.08 ppb and 0.025 ppm, between 0.08 ppb and 0.020 ppm, between 0.08 ppb and 0.016 ppm, between 0.08 ppb and 0.013 ppm, between 0.08 ppb to 10 ppb, 0.08 ppb to 8 ppb, 0.08 ppb to 6.35 ppb, 0.08 ppb to 5.05 ppb, 0.08 ppb to 4 ppb, 0 .08 ppb and 3.18 ppb, between 0.08 ppb and 2.53 ppb, between 0.08 ppb and 2.01 ppb, between 0.08 ppb and 1.59 ppb, between 0.08 ppb and 1, 27 ppb, between 0.08 ppb and 1.01 ppb, between 0.25 ppb and 0.8 ppm, between 0.25 ppb and 0.63 ppm, between 0.25 ppb and 0.50 ppm, between 0, 25 ppb and 0.40 ppm, between 0.25 ppb and 0.32 ppm, between 0.25 ppb and 0.25 p pm, between 0.25 ppb and 0.20 ppm, between 0.25 ppb and 0.16 ppm, between 0.25 ppb and 0.13 ppm, between 0.25 ppb and 0.10 ppm, between 0.25 ppb and 0.08 ppm, between 0.25 ppb and 0.06 ppm, between 0.25 ppb and 0.05 ppm, between 0.25 ppb and 0.04 ppm, between 0.25 ppb and 0.032 ppm, between 0.25 ppb to 0.025 ppm, 0.25 ppb to 0.020 ppm, 0.25 ppb to 0.016 ppm, 0.25 ppb to 0.013 ppm, 0.25 ppb to 10 ppb, 0.25 ppb to 8 ppb, between 0.25 ppb and 6.35 ppb, between 0.25 ppb and 5.05 ppb, between 0.25 ppb and 4 ppb, between 0.25 ppb and 3.18 ppb, or between 0.25 ppb and 2.53 ppb. Use of a lithium bis(fluorosulphonyl)imide salt according to any one of Claims 1 to 4 or according to Claim 5, in a Li-ion battery, in particular in Li-ion batteries of mobile devices, by mobile phones or laptop computers, electric vehicles, renewable energy storage, for example photovoltaics or wind power. Use according to claim 6, in a Li-ion battery operating at a charge cut-off voltage greater than or equal to 4.2V, preferably greater than or equal to 4.4V. An electrolyte composition comprising a lithium bis(fluorosulfonyl)imide salt according to any one of claims 1 to 4 or according to claim 5, and an organic solvent. Use of a lithium bis(fluorosulfonyl)imide salt according to any one of Claims 1 to 4 or according to Claim 5, for improving the life of a Li-ion battery and/or the electronic performance of a battery Li-ion, especially at a charging cut-off voltage greater than or equal to 4.4V.