EP4690340A1

EP4690340A1 - Electrolyte comprising sulfonamides and lithium salts, electrochemical cell and battery comprising said electrolyte, method of preparation and uses thereof

Info

Publication number: EP4690340A1
Application number: EP24717191.1A
Authority: EP
Inventors: María MARTÍNEZ-IBÁÑEZ; Michel Armand; Lorena GARCÍA; Eduardo GIL; Mikel ARRESE-IGOR; Leire MEABE; Vincent Giordani
Original assignee: Basquevolt SA
Current assignee: Basquevolt SA
Priority date: 2023-04-05
Filing date: 2024-04-04
Publication date: 2026-02-11
Also published as: WO2024208953A1; CN120958624A

Abstract

The present invention relates to a liquid electrolyte comprising: i. at least one sulfonamide with general formula CHF₂-S(O)₂-NR₁R₂, wherein R₁ and R₂ are independently selected from a linear or branched C₁-C₁₂ alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C₂-C₁₂ alkenyl group which may be substituted with one or more fluorine atom(s), a C₆- C₁₂ aryl group which may be substituted with one or more fluorine atom(s), and CH₂CH₂O-(CH₂CH₂O)n-R₃, wherein R₃ is a methyl or ethyl group and n is an integer from 0 to 20; or R₁ and R₂ may be combined with each other to form a nitrogen-containing aliphatic ring; and ii. at least one lithium salt; being said electrolyte further characterized in that: it does not comprise a polymer other than a sulfonamide-containing polymer and it further comprises at least one solvent suitable for dissolving the combination of i) and ii) when said combination is in solid form. Some remarkable advantages of the new electrolyte are the improved thermal stability and conductivity. The invention also relates to an electrochemical cell or battery comprising said electrolyte. The impedance and voltage profile of the electrochemical cell or battery comprising the electrolyte of the invention are favorable compared to state-of-art systems. Further, the present invention discloses sulfonamides with general formula CHF₂-S(O)₂- NR₁R₂ which are useful for preparing liquid electrolytes. The present invention also relates to methods for preparing sulfonamides, the liquid electrolyte and the electrochemical cell or battery comprising it.

Description

ELECTROLYTE COMPRISING SULFONAMIDES AND LITHIUM SALTS, ELECTROCHEMICAL CELL AND BATTERY COMPRISING SAID ELECTROLYTE, METHOD OF PREPARATION AND USES THEREOF.

FIELD OF THE INVENTION

The present invention relates to the field of electrolytes, particularly liquid electrolytes, for use in electrochemical cells or batteries. The present invention may find widespread application in energy storage and electronic devices.

BACKGROUND

Lithium metal batteries (LMBs) arguably represent an attractive technology for energy storage applications due to their high energy density and ultralow redox potential. Commercial batteries primarily use liquid electrolytes (LEs) as the ion-transport media owing to their high ionic conductivity and exceptional wettability with electrodes and separator. On the other hand, solid electrolytes, such as those made of polymers, ceramics or their hybrids, feature a lower conductivity than that of established liquid electrolytes.

Typical liquid electrolytes are organic carbonates and ethers, such as ethylene carbonate (EC), ethyl methyl carbonate (EMC), 1,2-dimethoxy ethane (DME), etc. However, liquid electrolytes may be associated to low thermal stability and sub-optimal electrodeelectrolyte interfacial resistance. These issues represent a major obstacle to a practical use of liquid electrolytes in LMBs.

Several sulfonamides have been used as component of liquid electrolytes, however other organic carbonates are generally required to achieve stable electrochemical cycling.

For example, document EP3050872A1 relates to an electrolyte solution comprising a fluorinated sulfonamide according to the general formula R^SCE-NTGRs as part of a solvent system and an electrolyte salt, however this document teaches that flammable carbonate solvents are essential to solve the corresponding technical problem (e.g., aluminum current collector corrosion) while maintaining high electrolyte conductivity.

US9065146B2 describes a non-aqueous electrolyte which comprises a non-aqueous organic solvent and a lithium salt dissolved therein, wherein the non-aqueous organic solvent contains at least one compound selected from the group consisting of acid anhydrides and carbonic esters having an unsaturated bond, and at least one compound selected from the group consisting of sulfonic compounds and fluorine-containing aromatic compounds having 9 carbon atoms or less.

WO2022216593A1 discloses electrolytes and electrochemical cells which comprise asymmetric sulfonamides, lithium salts and carbonates.

US8802301B2 refers to ionic liquid compositions as electrolytes for lithium-ion batteries containing an alkylsulfonamides or an arylsulfonamide and lithium fluoroalkylsulfonimides or fluoroarylsulfonimides under certain sulfonamide/lithium salt ratios and with a Tg of the resulting mixture lower than -50°C.

WO2022053881A1 discloses electrolyte composition that comprises one or more sulfonyl-based solvents for electrolytes used in electrochemical devices, such as secondary batteries. The electrolytes may include one or more salts, such as one or more alkali-metal salts, dissolved in said sulfonyl-based solvent system.

Despite the advances in the field, electrolyte systems displaying improved thermal stability, improved interfacial resistance and/or lead to high conductivity are yet to be discovered. Thus, there is a need in art to develop new electrolyte systems, particularly liquid electrolytes, which overcome the thermal stability issues of state-of-art liquid electrolytes and, at the same time, offer a viable electrochemical performance for widespread application.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a liquid electrolyte, comprising sulfonamides and lithium salts further characterized in that it does not comprise a polymer other than a sulfonamide- containing polymer, provided that said electrolyte further comprises at least one solvent suitable for dissolving the combination of sulfonamides and lithium salts, when the latter is in solid form. The inventors have found that such electrolyte composition displays advantageous properties, such as high thermal stability and improved interfacial resistance without compromising the electrolyte conductivity.

Thus, a first aspect of the invention refers to a liquid electrolyte, comprising: i. at least one sulfonamide with general formula I

I wherein Ri and R2 are independently selected from a linear or branched C1-C12 alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), a C >- C12 aryl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH₂CH2O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 20; or Ri and R2 may be combined with each other to form a nitrogen-containing aliphatic ring; and i. at least one lithium salt; being said electrolyte further characterized in that:

- it does not comprise a polymer other than a sulfonamide-containing polymer, and

- it further comprises at least one solvent suitable for dissolving the combination of i) and ii) when said combination is in solid form.

A second aspect of the invention refers to an electrochemical cell or battery comprising the electrolyte of the invention as defined above.

A third aspect of the invention refers to a method for preparing the electrolyte of the first aspect of the invention comprising the steps of:

(i) providing at least one lithium salt;

(ii) mixing at least one sulfonamide of formula I with the at least one lithium salt of step (i) to obtain a first mixture;

(iii) when the first mixture is in solid form, adding to the first mixture at least one solvent suitable for dissolving it, thus obtaining a second mixture; and

(iv) stirring the mixture from step (ii) or (iii).

A further aspect of the invention refers to the use of the electrochemical cell or battery of the second aspect of the invention in electric motors; electric cars, including electric vehicles (EV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), or the like; electric carts, including electric bikes (E-bikes) and electric scooters (E- scooters); electric golf carts; and electric power storage systems.

An additional aspect of the present invention also refers to a sulfonamide of formula I:

I wherein Ri and R2 are independently selected from a linear or branched C1-C12 alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), a CL- C12 aryl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH₂CH2O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 20; or Ri and R2 may be combined with each other to form a nitrogen-containing aliphatic ring, provided that:

- Ri and R2 are not simultaneously ethyl;

- Ri and R2 are not simultaneously -CH2-CH=CH2; and

- Ri is unsubstituted phenyl and R2 is methyl or viceversa.

Lastly, the present invention also refers to a method of preparing a sulfonamide of formula I, as defined above, wherein said method comprises adding a solution of a compound of formula la to a solution of a compound of formula lb

,^R1

H-N

R₂ lb . wherein Ri and R2 are as defined in the previous aspect of the invention; and said method optionally further comprises purifying the so-obtained sulfonamide of formula I as defined above.

DESCRIPTION OF THE FIGURES

Figure 1. Thermogravimetric analysis (TGA) traces for (a) TFSA11, (b) DFSA11, (c) TFSA11/LiFSI, (d) DFSA11/LiFSI.

Figure 2. Impedance plots of the Li-symmetric cells: TFSA11/LiFSI (left), and DFSA11/LiFSI (right) measured at 25 °C. Figure 3. Voltage profile of the galvanostatic cycling of Li-symmetric cells in TFSAl l/LiFSI (a) and DFSAl l/LiFSI (b) with a total capacity of 1 mAh cm'² and varying the C-rate at 25 °C.

DETAILED DESCRIPTION OF THE INVENTION

All terms as used herein in this application, unless otherwise stated, shall be understood in their ordinary meaning as known in the art. Other more specific definitions for certain terms as used in the present application are as set forth below and are intended to apply uniformly throughout the specification and claims unless an otherwise expressly set out definition provides a broader definition.

Throughout the description and claims the word “comprises" and variations of the word, are not intended to exclude other technical features, additives, components or steps. Furthermore, the word “comprise” encompasses the cases of “consist of’ and “consists essentially of’. Additional objects, advantages and features of the invention will become apparent to those skilled in the art upon examination of the description or may be learned by practice of the invention.

Throughout the description and claims, the terms “blend(s)” and “mixture(s)” will be used interchangeably.

For the purposes of the invention, any ranges given include both the lower and the upper end-points of the range. Ranges or values given, such as temperatures, times, molar ratio, volume ratio and the like, should be considered approximate when they are defined by the term “about” (i.e. with a 5% margin of variation around indicated point).

As mentioned above, a first aspect of the invention refers to a liquid electrolyte, comprising: i. at least one sulfonamide with general formula I

\ *? ,^R1

V S-N

F o R2

I wherein Ri and R2 are independently selected from a linear or branched C1-C12 alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), a Ce- C12 aryl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH2CH₂O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 20; or Ri and R2 may be combined with each other to form a nitrogen-containing aliphatic ring; and ii. at least one lithium salt; being said electrolyte further characterized in that:

More embodiments regarding the first aspect of the invention will be given below.

Sulfonamide

The liquid electrolyte of the present invention comprises at least one sulfonamide of formula I as shown above. The term “sulfonamide” in the context of the present invention denotes an organic compound containing the core functional group >N-S(=O)₂- where the N atom is attached to two more organic moieties Ri and R2 while the S atom is further attached to a fragment CHF2. In a particular embodiment, the liquid electrolyte of the present invention comprises one sulfonamide of formula I; in another particular embodiment, it comprises two or more sulfonamides of formula I; in yet another embodiment, it comprises three or more sulfonamides of formula I.

In an embodiment, the groups Ri and R2 are the same. In another embodiment, the groups Ri and R2 are different.

Typically, the groups Ri and R2 are independently selected from a linear or branched Ci- C12 alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), a C6-C12 aryl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH₂CH2O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 20; or Ri and R2 may be combined with each other to form a nitrogen-containing aliphatic ring.

A “Ci-C 12 alkyl” as used herein refers to a branched or linear aliphatic carbon chain consisting of 1 to 12 carbon atoms. Illustrative examples of C1-C12 alkyl groups include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, pentyl, hexyl, heptyl, octyl, etc. In preferred embodiments, the aliphatic chain may comprise less carbon atoms, for example 6 (“Ci-Ce alkyl”) or 3 (“C1-C3 alkyl”) carbon atoms. Methyl groups are the most preferred alkyl groups. The alkyl chain may be partially or completely fluorinated (“perfluorinated”), meaning that at least one but not all hydrogen atoms of any C-H bond is replaced by a fluorine atom or that all hydrogen atoms of any C-H bond is replaced by a fluorine atom, respectively.

A “C2-C12 alkenyl” as used herein refers to linear or branched aliphatic groups having from 2 to 12 carbon atoms and having at least 1 double C=C bond. Such alkenyl groups include ethenyl (-CH=CH2), n-2-propenyl (allyl, -CH2CH=CH2) and the like.

A “C6-C12 aryl” as used herein refers to aromatic hydrocarbon rings that contain 6 to 12 carbon atoms, also as two fused rings, optionally substituted with alkyl groups as already defined above, such as phenyl, a-naphthyl, P-naphthyl, m-methylphenyl, p- trifluoromethylphenyl and the like.

More particularly, Ri and R2 are independently selected from a linear or branched C1-C12 alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH2CH2O)_n-R3, wherein R3 is H or a methyl group and n is an integer from 0 to 10; or Ri and R2 may be combined with each other to form a 3- to 7- membered nitrogen-containing aliphatic ring.

Preferably, Ri and R2 are independently selected from a linear or branched Ci-Ce alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C6 alkenyl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH₂CH2O)_n-R3, wherein R3 is H or a methyl group and n is an integer from 0 to 10; or Ri and R2 may be combined with each other to form a 3- to 7-membered nitrogen-containing aliphatic ring.

More preferably, Ri and R2 are independently selected from a linear or branched Ci-Ce alkyl group, a linear or branched C2-C6 alkenyl group, and CH2CH2O-(CH2CH2O)_n-R3, wherein R3 is a methyl group and n is an integer from 0 to 5; or Ri and R2 may be combined with each other to form a 3- to 7-membered nitrogen-containing aliphatic ring. Even more preferably, Ri and R2 are independently selected from a linear Ci-Ce alkyl group, a C2-C6 alkenyl group, and a -CH2CH2OCH2CH2O-CH3 group; or Ri and R2 may be combined with each other to form a 3- to 6-membered nitrogen-containing aliphatic ring. Even more preferably, Ri and R2 are selected from a linear C1-C3 alkyl group, a C2-C3 alkenyl group, and -CH2CH2O-CH3. More preferably, Rl and R2 are independently a linear C1-C3 alkyl group.

In the most preferred embodiment, Ri = R2 = CH3.

The at least one sulfonamide may vary from 5 to 95 wt.% of the weight of the electrolyte; preferably from 10 to 90 wt.% of the weight of the electrolyte, more preferably from 50 to 90 wt.% of the weight of the electrolyte; even more preferably, the at least one sulfonamide is about 88 wt.% of the weight of the electrolyte.

The electrolyte of the invention is further characterized in that it does not comprise a polymer other than a “sulfonamide-containing polymer”, which is a polymer with a functional group >N-S(=O)2- where the N atom is attached to two more organic moieties while the S atom is further attached to another organic moiety. In a particular embodiment, such “sulfonamide-containing polymer” is a sulfonamide of formula I where Ri and R2 are defined in such a manner that the resulting sulfonamide is a polymer. In another embodiment, the electrolyte of the first aspect of the invention does not comprise a polymer selected from the group consisting of sulfonamide-containing polymers, polyalkylene oxides, polyalkylenimines, polyalkylene sulphides, poly(meth)acrylates, polyphosphazenes, polysiloxanes, polyvinyl alcohol (PVA), polyvinyl amine (PVAm), polyvinyl acetate (PVAc), polyvinyl halides, polyvinylidene difluoride-hexafluropropylene (PVdF-HFP), polyacrylonitrile (PAN), poly(vinylpyrrolidone) (PVP), poly(2-vinylpyridine), poly(s-caprolactone) (PCL), polymaleimides and their alternate polymers with alkenes, polyaniline (PANI), chitosan (CS), or any blend or any copolymer or any cross-linked polymer thereof.

Lithium salt

The at least one lithium salt comprised in the liquid electrolyte, may be an organic lithium salt, an inorganic lithium salt, or a combination thereof.

Specifically, the inorganic lithium salt may include, but is not limited to, LiCICU, LiNCh, LiBF4, LiAsFe, LiPFe, LiBFsCl, and LiF.

The organolithium salt may include, but is not limited to, LiN(SO2CF3)2 (or LiTFSI), LiN(SO2CF₃)(SO2CF₂H) (or LiDFTFSI), LiN(SO₂F)₂ (or LiFSI), LiN(SO₂CF3)(SO₂F), LiN(C₂F₅SO₂)(SO₂F), LiB(C₂O₄)₂, LiBF₂(C₂O₄), LiC(SO₂CF₃)₃, LiPF₃(C₂F₅)₃, and LiCF₃SO₃.

In an embodiment, the at least one lithium salt is selected from LiC10₄, LiNO₃, LiBF₄, LiAsF₆, LiPF₆, LiBF₃Cl, LiF, LiN(SO₂CF₃)₂, LiN(SO₂CF₃)(SO₂CF₂H), LiN(SO₂F)₂, LiN(SO₂CF₃)(SO₂F), LiN(C₂F₅SO₂)(SO₂F) LiB(C₂O₄)₂, LiBF₂(C₂O₄), LiC(SO₂CF₃)₃, LiPF₃(C₂Fs)₃, LiCF₃SO₃ or a combination thereof.

In another embodiment, the at least one lithium salt is selected from LiN(SO₂CF₃)₂, LiN(SO₂CF₃)(SO₂CF₂H), LiN(SO₂F)₂, LiN(SO₂CF₃)(SO₂F), LiB(C₂O₄)₂, LiBF₂(C₂O₄), LiC(SO₂CF₃)₃, LiPF₃(C₂Fs)₃, LiCF₃SO₃, and LiNO₃ or a combination thereof.

In a preferred embodiment, the at least one lithium salt is an organic lithium salt, preferably selected from LiN(SO₂CF₃)(SO₂CF₂H), LiB(C₂O₄)₂, LiBF₂(C₂O₄), LiN(SO₂F)₂, LiN(SO₂CF₃)₂, LiN(SO₂CF₃)(SO₂F), or a combination thereof; more preferably, the organic lithium salt is selected from LiN(SO₂CF₃)(SO₂CF₂H), LiN(SO₂F)₂, LiN(SO₂CF₃)₂, or a combination thereof.

In a preferred embodiment, only one lithium salt is comprised in the electrolyte. In a further embodiment, the lithium salt comprised in the liquid electrolyte, is LiN(SO₂CF₃)(SO₂CF₂H), LiN(SO₂F)₂, or LiN(SO₂CF₃)₂

The at least one lithium salt comprised in the liquid electrolyte, may vary from 5 to 25 wt.%, preferably from 8 to 18 wt.%, even more preferably from 10 to 15 wt.%, even more preferably to about 12 wt.% with respect to the total weight of the electrolyte.

In another embodiment of the first aspect of the invention, the electrolyte is further characterized in that it does comprise an organic carbonate. In another embodiment of the first aspect of the invention, the electrolyte is further characterized in that it does not comprise an organic carbonate. For the purpose of the invention, any carbonate O=C(-O’ )₂ that contains an organic, cyclic or linear chain with at least C and H atoms has to be considered an organic carbonate. The organic carbonate is preferably a liquid at room temperature. As practical examples, the definition of organic carbonates includes, even though the list is non-limiting, cyclic alkylene carbonates (ethylene carbonate, propylene carbonate, butylene carbonate and the likes) and di(hydrocarbyl) carbonates, such as dialkyl carbonates, diaryl carbonates, alkyl aryl carbonates or mixtures thereof.

In a particular embodiment, substituted derivatives of the aforementioned organic carbonates are also included or excluded from the liquid electrolyte of this invention. One or more substituents may be present on the alkylene, alkyl or aryl moieties. Non-limiting examples of substituents include halogen, alkoxy, hydroxyl, nitrogen substituents, phosphorous substituents, sulphur substituents and similar moieties.

Solvent

In a particular embodiment, the electrolyte of the first aspect of the invention further comprises at least one solvent suitable for dissolving the combination of i) and ii) when said combination is in solid form.

However, in another particular embodiment, the liquid electrolyte composition of the invention may optionally further comprise at least one solvent suitable for dissolving the lithium salt(s) of the electrolyte.

In a particular embodiment, when the electrolyte of the invention is characterized in that it does not comprise a carbonate, the solvent cannot be a carbonate-based solvent.

Examples of solvents are organic solvents such as dimethoxy ethane (DME), 1,2- diethoxyethane (DEE), 1,3-dioxolane (DOL), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (G3), tetraethylene glycol dimethyl ether (TEGDME), poly(ethylene glycol) dimethyl ether (PEGDME), tetrahydropyran (THP), 4-methyltetrahydropyran, y-butyrolactone, tetrahydrofuran (THF), 2- methyltetrahydrofuran, diethylether, methyl-tert-butylether, succinonitrile (SN), glutaronitrile (GN), adiponitrile (AN), N,N-dimethylsulfamoyl fluoride (FSA), N,N- dimethyltrifluoromethane-sulfonamide (TFSA), and any mixtures thereof.

When the electrolyte further comprises at least one solvent, this is present in an amount ranging from 1 to 50 wt% with respect to the total weight of the electrolyte, preferably from 1 to 40 wt%, more preferably from 1 to 30 wt%, even more preferably from 1 to 20 wt% with respect to the total weight of the electrolyte.

In a preferred embodiment when the electrolyte further comprises at least one solvent:

- the amount of the at least one sulfonamide may vary from 5 to 90 wt.% of the weight of the electrolyte; preferably from 10 to 90 wt.% of the weight of the electrolyte, more preferably from 50 to 90 wt.% of the weight of the electrolyte; even more preferably, the at least one sulfonamide is about 88 wt.% of the weight of the electrolyte; - the amount of the at least one lithium salt may vary from from 5 to 25 wt.%, preferably from 8 to 18 wt.%, even more preferably from 10 to 15 wt.%, even more preferably to about 12 wt.% with respect to the total weight of the electrolyte; and,

- the amount of the at least one solvent may vary from 1 to 70 wt.%, preferably from 1 to 50 wt.%, even more preferably from 1 to 25 wt.% with respect to the total weight of the electrolyte.

Thermal stability

The electrolyte of the invention is characterized in that it possesses high thermal stability compared to state-of-art liquid electrolytes. In particular, the thermal stability can be determined by measuring the mass of the electrolyte over time in a wide range of temperature. In an embodiment, the thermal stability of the electrolyte is determined by thermogravimetric analysis (TGA). In particular, a species is considered thermally stable at a certain temperature or in a temperature range if there will be no observed mass change at said temperature or temperature range. In particular, the range evaluated for the electrolyte of the present invention is from room temperature up to 600 °C. In a preferred embodiment, the TGA measurements are performed under inert gas. In another preferred embodiment, the heating rate is of 10 °C min'¹. In the most preferred embodiment, the thermal stability is determined by thermogravimetric analysis under argon atmosphere and at a heating rate of 10 °C min'¹ in the range from room temperature up to 600 °C.

According to the embodiments above, the electrolyte of the invention is thermally stable up to a temperature of 150 °C, preferably up to 120 °C, more preferably up to 90°C, even more preferably in the range from room temperature up to about 83 °C. This improved thermal stability of the electrolyte of the invention has practical advantages since it may significantly broaden the temperature range of use of the electrochemical cell or battery comprising said electrolyte.

Further embodiments of the electrolyte

In an embodiment of the invention, the liquid electrolyte consists of i. at least one sulfonamide with general formula I

I wherein Ri and R2 are independently selected from a linear or branched C1-C12 alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), a C >- C12 aryl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH₂CH2O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 20; or Ri and R2 may be combined with each other to form a nitrogen-containing aliphatic ring, and i. at least one lithium salt; and wherein additionally at least one solvent suitable for dissolving the combination of i) and ii) is present when said combination is in solid form.

In another embodiment of the invention, the liquid electrolyte consists of i. one sulfonamide with general formula I

I wherein Ri and R2 are independently selected from a linear or branched C1-C12 alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), a C >- C12 aryl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH₂CH2O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 20; or Ri and R2 may be combined with each other to form a nitrogen-containing aliphatic ring; and ii. one lithium salt; and wherein additionally at least one solvent suitable for dissolving the combination of i) and ii) is present when said combination is in solid form.

I wherein Ri and R2 are independently selected from a linear or branched C1-C12 alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), a Ce- C12 aryl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH₂CH2O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 20; or Ri and R2 may be combined with each other to form a nitrogen-containing aliphatic ring; i. one lithium salt; and ii. one solvent.

In another embodiment, the liquid electrolyte comprises: i. one sulfonamide with general formula I

I wherein Ri and R2 are independently selected from a linear or branched Ci-Ce alkyl group, a linear or branched C2-C6 alkenyl group, and CH2CH2O-(CH2CH2O)_n-R3, wherein R3 is a methyl group and n is an integer from 0 to 5; or Ri and R2 may be combined with each other to form a 3- to 6-membered nitrogen-containing aliphatic ring; ii. at least one lithium salt selected from the group consisting of LiC10₄, LiNCh, LiBF₄, LiAsF₆, LiPF₆, LiBF₃Cl, LiF, LiN(SO₂CF₃)2, LiN(SO₂CF3)(SO2CF₂H), LiN(SO₂F)₂, LiN(SO2CF₃)(SO₂F), LiN(C₂F₅SO2)(SO₂F) LiB(C₂O₄)₂, LiBF2(C2O₄), LiC(SO2CF3)3, LiPF3(C2Fs)3, LiCFs SO3 and a combination thereof; being said electrolyte further characterized in that it does not comprise a polymer other than a sulfonamide-containing polymer.

In a particular embodiment of the latter:

- the amount of the one sulfonamide may vary from 5 to 95 wt.% of the weight of the electrolyte; preferably from 10 to 90 wt.% of the weight of the electrolyte, more preferably from 50 to 90 wt.% of the weight of the electrolyte; even more preferably, the at least one sulfonamide is about 88 wt.% of the weight of the electrolyte; and/or

- the amount of the at least one lithium salt may vary from 5 to 25 wt.%, preferably from 8 to 18 wt.%, even more preferably from 10 to 15 wt.%, even more preferably to about 12 wt.% with respect to the total weight of the electrolyte.

I wherein Ri and R2 are independently selected from a linear or branched Ci-Ce alkyl group, a linear or branched C2-C6 alkenyl group, and CH2CH2O-(CH2CH2O)_n-R3, wherein R3 is a methyl group and n is an integer from 0 to 5; or Ri and R2 may be combined with each other to form a 3 - to 6-membered nitrogen-containing aliphatic ring, i. at least one lithium salt selected from the group consisting of LiC10₄, LiNCh, LiBF₄, LiAsF₆, LiPF₆, LiBF₃Cl, LiF, LiN(SO₂CF₃)2, LiN(SO₂CF3)(SO2CF₂H), LiN(SO₂F)₂, LiN(SO2CF₃)(SO₂F), LiN(C₂F₅SO2)(SO₂F) LiB(C₂O₄)₂, LiBF2(C2O₄), LiC(SO2CF3)3, LiPF3(C2Fs)3, LiCFs SO3 and a combination thereof; and ii. at least one solvent; being said electrolyte further characterized in that it does not comprise a polymer other than a sulfonamide-containing polymer of general formula I.

In a particular embodiment of the latter:

- the amount of the sulfonamide may vary from 5 to 90 wt.% of the weight of the electrolyte; preferably from 10 to 90 wt.% of the weight of the electrolyte, more preferably from 50 to 90 wt.% of the weight of the electrolyte; even more preferably, the at least one sulfonamide is about 88 wt.% of the weight of the electrolyte;

- the amount of the at least one lithium salt may vary from from 5 to 25 wt.%, preferably from 8 to 18 wt.%, even more preferably from 10 to 15 wt.%, even more preferably to about 12 wt.% with respect to the total weight of the electrolyte; and, - the amount of the at least one solvent may vary from 1 to 70 wt.%, preferably from 1 to 50 wt.%, even more preferably from 1 to 25 wt.% with respect to the total weight of the electrolyte.

In further embodiments, the liquid electrolyte comprises: i. a sulfonamide of formula ii. an organic lithium salt selected from LiN(SO2CF3)(SO2CF2H), LiN(SO2F)2, LiN(SO2CF3)2, or a combination thereof; and iii. optionally, a solvent, wherein the weight ratio between the sulfonamide and the organic lithium salt may vary from 80:20 to 95:5; being said electrolyte further characterized in that it does not further comprise a polymer.

In further embodiments, the liquid electrolyte consists of: i. a sulfonamide of formula ii. an organic lithium salt selected from LiN(SO2CF3)(SO2CF2H), LiN(SO2F)2, LiN(SO2CF3)2, or a combination thereof; wherein the weight ratio between the sulfonamide and the organic lithium salt may vary from 80:20 to 95:5.

Electrochemical cell and battery

The electrolyte of the first aspect of the invention is particularly useful in electrochemical devices such as electrochemical cells or batteries, particularly secondary electrochemical cells or batteries wherein the cell reactions are reversible.

The second aspect of the invention relates to an electrochemical cell or a battery comprising the liquid electrolyte according to the first aspect of the invention.

In a preferred embodiment, the second aspect of the invention relates to an electrochemical cell or a battery comprising the electrolyte according to any, preferred or particular, embodiment of the first aspect of the invention defined above, and further comprising an anode, a cathode and, optionally, a separator.

In a preferred embodiment, the second aspect of the invention relates to a lithium metal battery comprising the electrolyte according to any embodiment of the first aspect of the invention defined above. A lithium metal battery is a battery characterized in that it comprises an anode consisting essentially of metallic lithium.

In a further preferred embodiment, the second aspect of the invention relates to a lithium metal battery comprising a cathode wherein the cathode material is selected from the group consisting of lithium manganese oxide, lithium nickel oxide, lithium nickel manganese cobalt oxide, lithium nickel manganese oxide, lithium manganese cobalt oxide, lithium copper oxide, lithium copper sulphide, lithium iron phosphate, lithium iron sulphide, lithium manganese iron phosphate and lithium nickel cobalt aluminium oxide. In a further preferred embodiment, the second aspect of the invention relates to a lithium metal battery comprising a cathode wherein the cathode material is lithium nickel manganese cobalt oxide such as LiNio.6Mno.2Coo.2O2 (NMC622). The lithium nickel manganese cobalt oxide cathode may additionally contain other additives, such as a conductive carbon and a polymeric binder. In an embodiment, the cathode consists of NMC622, carbon black as conductive carbon and polyvinylidene fluoride (PVdF) as a polymeric binder. It is preferred that the weight ratio between NMC622: conductive carbon: polymeric binder is about 90:5:5.

In a further preferred embodiment, the second aspect of the invention relates to a lithium metal battery further comprising a separator membrane, such as a polypropylene membrane, preferably microporous polypropylene, arranged between at least one electrode and the electrolyte in such a configuration that lithium cations can flow across said membrane between the electrolyte and the surface of said at least one electrode. In specific embodiments, the separator membrane has a thickness of between 1 and 50 pm, preferably of between 15 and 35 pm, more preferably of about 25 pm. The porosity of the separator membrane may also vary between a certain range, particularly the average pore diameter is comprised between 0.001 and 0.100 pm, preferably between 0.020 and 0.080 pm, more preferably is about 0.064 pm.

In a further preferred embodiment, the electrochemical cell or lithium metal battery of the second aspect of the invention has a low resistance at the interface between the electrolyte and lithium metal electrode. In particular, the interfacial resistance may be determined by measuring electrochemical impedance spectra (EIS) of the electrochemical cell or lithium metal battery using a potentiostat. More particularly, electrochemical impedance spectra recorded in the range from 10⁶ to IO^-2 Hz at 25 °C. According to any of the above embodiments, the electrochemical cell or lithium metal battery has an electrochemical impedance lower than 100 cm², preferably lower than 75 cm², more preferably lower than 50 cm², even more preferably of about 35 cm².

Uses of the electrochemical cell of battery

The electrochemical cell or battery comprising the electrolyte of the invention may be applied to a variety of electronic devices which may include, but are not limited to: electric motors; electric cars, including electric vehicles (EV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), or the like; electric carts, including electric bikes (E-bikes) and electric scooters (E-scooters); electric golf carts; electric power storage systems; or the like.

Methods for preparing the electrolyte

As defined above, a third aspect of the invention relates to a method for the preparation of the liquid electrolyte according to the first aspect of the invention, said method comprising the steps of:

(i) providing at least one lithium salt;

(iv) stirring the mixture from step (ii) or (iii).

In a particular embodiment, steps (i) and (ii) of the method above may be performed by using the neat components of the electrolyte (e.g. the neat solid or liquid) or, alternatively, said components may be dissolved in at least one solvent prior to or after mixing. The use of the at least one solvent is particularly needed when the mixture of the sulphonamide of formula (I) and the lithium salt is solid. By “solid form”, a skilled person would refer to a pure substance or mixture which is solid under standard conditions, that is about 1 bar pressure and room temperature (20- 25 °C).

However, the at least one solvent may optionally be used when the mixture of the at least one sulphonamide of formula (I) and the at least one lithium salt is liquid.

Suitable solvents for dissolving the at least one lithium salt and/or at least one sulfonamide would be immediately known to a skilled person and would typically be polar organic solvents. Examples of organic solvents suitable for dissolving the lithium at least one lithium salt and/or at least one sulfonamide have been listed above.

In a preferred embodiment, steps (i)-(ii) are carried out by using the neat components (lithium salt and sulfonamide) with no further solvent, as the sulfonamide serves to dissolve the at least one lithium salt.

In another embodiment, the method for preparing the electrolyte of the invention is carried out by adding a solvent to the first mixture of step (ii) to assist the solubilisation of the at least one lithium salt and/or at least one sulfonamide towards obtaining the liquid electrolyte.

It is preferable that the mixture obtained from step (ii) or (iii) is stirred for a certain time to ensure that a homogeneous solution is obtained (i.e. no suspended matter is visible). The stirring is performed magnetically at 100 rpm, at 200 rpm, at 300 rpm, at 400 rpm, at 500 rpm, at 600 rpm, at 700 rpm, at 800 rpm, at 900 rpm, at 1000 rpm; preferably the stirring is performed in a range between 100 and 500 rpm, even more preferably at about 300 rpm. Additionally, the mixture from step (iii) is stirred for at least 5 min, at least 15 min, at least 30 min, at least 1 hour, at least 2 hours, at least 4 hours, at least 6 hours, at least 12 hours, at least 1 day; preferably, the mixture from step (iii) is stirred for 1 to 4 hours, more preferably for 2 hours.

All the steps of the method above are performed at a temperature comprised between 10 and 30 °C, preferably between 15 and 25 °C, even more preferably between 20 and 25 °C (room temperature).

Sulfonamides of formula I

As stated above, an additional aspect of the present invention also refers to a sulfonamide of formula I:

I wherein Ri and R2 are independently selected from a linear or branched C1-C12 alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), a Ce- C12 aryl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH₂CH2O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 20; or Ri and R2 may be combined with each other to form a nitrogen-containing aliphatic ring; and provided that

- Ri and R2 are not simultaneously ethyl;

- Ri and R2 are not simultaneously -CH2-CH=CH2; and

- Ri is unsubstituted phenyl and R2 is methyl or viceversa.

The sulfonamides of formula I are suitable for being used liquid electrolytes as defined in the first aspect of the invention.

In an embodiment Ri and R2 are the same. In another embodiment, Ri and R2 are different. In a further embodiment of the sulfonamide of formula I:

I

Ri and R2 are independently selected from a linear or branched C1-C12 alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), a C6-C12 aryl group which may be substituted with one or more fluorine atom(s), and CH2CH2O- (CH2CH2O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 20; or Ri and R2 may be combined with each other to form a nitrogen-containing aliphatic ring; and provided that Ri and R2 are not simultaneously methyl or ethyl.

In a particular embodiment, Ri and R2 are independently selected from a linear or branched C1-C12 alkyl group which is substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), a Ce-Cn aryl group which is substituted with one or more fluorine atom(s), and CH2CH2O-(CH2CH2O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 20; or Ri and R2 may be combined with each other to form a nitrogencontaining aliphatic ring; and provided that Ri and R2 are not simultaneously ethyl.

In another particular embodiment, Ri and R2 are independently selected from a linear or branched C1-C12 alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), a C6-C12 aryl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH2CH2O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 20; or Ri and R2 may be combined with each other to form a nitrogencontaining aliphatic ring; and provided that:

Ri and R2 are not simultaneously ethyl; and when Ri is methyl then R2 is also methyl.

More particularly, Ri and R2 in said sulfonamide are independently selected from a linear or branched C1-C12 alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH2CH2O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 10; or Ri and R2 may be combined with each other to form a nitrogen-containing aliphatic ring; provided that Ri and R2 are not simultaneously ethyl.

In a preferred embodiment, Ri and R2 are independently selected from a linear or branched Ci-Ce alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C6 alkenyl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH2CH2O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 10; or Ri and R2 may be combined with each other to form a 3- to 6-membered nitrogen-containing aliphatic ring; provided that Ri and R2 are not simultaneously ethyl.

In a more preferred embodiment, Ri and R2 are independently selected from a linear or branched Ci-Ce alkyl group, a linear or branched C2-C6 alkenyl group, and CH2CH2O- (CH2CH2O)_n-R3, wherein R3 is a methyl group and n is an integer from 0 to 5; or Ri and R.2 may be combined with each other to form a 3- to 6-membered nitrogen-containing aliphatic ring; provided that Ri and R2 are not simultaneously ethyl.

In an even more preferred embodiment, Ri and R2 are independently selected from a linear or branched Ci-Ce alkyl group, a linear or branched C2-C6 alkenyl group, or Ri and R2 may be combined with each other to form a 3- to 6-membered nitrogen-containing aliphatic ring; provided that Ri and R2 are not simultaneously ethyl. Most preferably, Ri and R2 are independently selected from a linear or branched Ci-Ce alkyl group, more preferably from a linear or branched C1-C3 provided that Ri and R2 are not simultaneously ethyl, even more preferably Ri and R2 are methyl.

In an embodiment, Ri and R2 are independently selected from a linear C3-C6 alkyl group, a C2-C6 alkenyl group, and -CH2CH2OCH2CH2O-CH3; or Ri and R2 may be combined with each other to form a 3- to 6-membered nitrogen-containing aliphatic ring.

In another embodiment, Ri and R2 are selected from methyl, ethyl, n-propyl, isopropyl, a C2-C3 alkenyl group, and -CH2CH2O-CH3, provided that Ri and R2 are not simultaneously methyl or ethyl.

Method of preparing sulfonamides

The present invention also refers to a method for preparing a sulfonamide of formula I, as defined in the previous inventive aspect, wherein said method comprises adding a solution of a compound of formula la to a solution of a compound of formula lb

,^R1

H-N

R₂ lb wherein Ri and R2 are as defined in any embodiment of the previous aspect of the invention; and wherein said method optionally further comprises purifying the so-obtained sulfonamide of formula I as defined in any of the embodiments of the previous aspect. It is preferred that the compounds la and lb are dissolved in a solvent prior to the addition. Any solvent can be used for dissolving the compounds la and lb, preferably these are chlorinated solvents (i.e. solvents containing at least one Cl atom), more preferably the solvent is dichloromethane (DCM). Preferred concentrations of compounds la and lb in their corresponding solvent are between 0.001M and 5.0M; preferably the concentrations of compound la and lb in their corresponding solvent are, each independent on the other, between 1.0 and 2.0M. In another embodiment, the concentrations of compound la and lb in their corresponding solutions are, each independent on the other, 0.001M, 0.005M, 0.01M, 0.05M, 0.1M, 0.5M, 1.0M, 1.5M, 2.0M, 2.5M, 3.0M, 3.5, 4.0M, 4.5M, or 5.0M. In a particular embodiment, a solution of a compound of formula la is added to a solution of compound of formula lb

,^R1

H-N

R₂ lb wherein Ri and R2 are as defined in any of the embodiments of the previous aspect of the invention, below room temperature, preferably below 0 °C, more preferably below -20 °C, even more preferably below -40 °C. In a preferred embodiment, compounds la and lb are reacted at a temperature ranging from 0 °C and -100 °C, preferably ranging from - 20 °C and -100 °C, more preferably ranging from -40 °C and -100 °C; most preferably the reaction temperature is about -78 °C. Preferably the addition of the solution of la is performed dropwise.

After the addition of compound la to compound lb is completed, the mixture is stirred at a temperature below room temperature, preferably below 0 °C, more preferably below - 20 °C, even more preferably below -40 °C. In a preferred embodiment, compounds la and lb are reacted at a temperature ranging from 0 °C and -100 °C, preferably ranging from - 20 °C and -100 °C, more preferably ranging from -40 °C and -100 °C; most preferably the reaction temperature is about -78 °C.

After an appropriate reaction time the reaction is quenched, preferably by the addition of water. The reaction time would depend on the specific compounds, however, it is preferred that the reaction time is at least 1 min, at least 5 min, at least 15 min, at least 30 min, at least 1 hour, at least 2 hours, at least 3 hours, at least 4 hours, at least 5 hours, at least 6 hours. Preferably, the reaction time is comprised between 1 min and 12 hours, between 30 min and 10 hours, between 1 hour and 8 hours.

Following the above method, a sulfonamide of formula I is obtained.

The method may further comprise an optional purification step, where the sulfonamide of formula I is isolated in pure form. The purification step may involve several known techniques, such as organic solvent extraction, solvent evaporation, distillation, and drying.

EXAMPLES

The following examples are intended to illustrate but not to limit the disclosed embodiments.

List of abbreviations and acronyms

LiFSI: lithium bis(fluorosulfuryl) imide

TFSA11 : AA-dimethyltrifluoromethane sulfonamide

DFSA11 : M -dimethyldifluoromethane sulfonamide rpm: rotations per minute RT : room temperature

Reagents and starting materials

Difluoromethanesulfonyl chloride (Manchester Organics Limited), 2M THF solution of dimethylamine (Thermo Scientific), magnesium sulfate (Thermo Scientific), LiFSI (Nippon shokubai) and dichloromethane (Fisher Scientific) were purchased and used without any prior pre-treatment.

Example 1 : Preparation of N,N-dimethyldifluoromethane sulfonamide (DFSA11) and

M -dimethyltrifluorornethane sulfonamide (TFSA11) Synthesis of DFSA11 : To a mechanically stirred solution of dimethylamine (3 eq) in DCM (2M) at -78°C, a solution of difluoromethanesulfonyl chloride (DFSC1, 1 eq) in DCM (IM) was added dropwise, and the mixture was stirred at -78°C under Ar atmosphere. After 6 hours the reaction was quenched by the addition of water. The aqueous phase was extracted with DCM (3 x 20mL) and the combined organic fractions were dried over anhydrous Na2SO4. After DCM was removed by rotary evaporation, a pale yellow liquid was obtained which was purified by distillation under reduced pressure, affording DFSA11 as a colourless liquid (yield: 38%). NMR (CDC13): 6 3.0 (s). ¹⁹F NMR: 6 -75 (d).

CF3- 9S-CI - Y » CF3- 9S-N R. DCM, -78 °C R2

Synthesis of TFSA11 : To a mechanically stirred solution of dimethylamine (3 eq) in DCM (2 M) at -78°C, a solution of trifluoromethanesulfonyl chloride (TFSC1, 1 eq) in DCM (I M) was added dropwise, and the mixture was stirred at -78°C under argon atmosphere. After 3 hours the reaction was quenched by the addition of water. The aqueous phase was extracted with DCM and the combined organic fractions were dried over anhydrous Na2SO4. After DCM was removed by rotary evaporation, a pale yellow liquid was obtained which was purified by distillation under reduced pressure, obtaining TFSA11 was a colourless liquid, (yield: 38%). ’H NMR (CDC13): 6 3.1 (s), 6.2 (t). ¹⁹F NMR: 6 -120 (d) ppm.

Example 2: Preparation of the electrolyte of the invention and comparative electrolyte Salt lithium bis(fluorosulfuryl) imide, LiN(SO2F)2 (0.15 g), was placed into a vial, then MA-dimethyldifluoromethane sulfonamide (DFSA11, 1.10 g, 735 pL) was added and the mixture was left under stirring for approximately 2 hours (300 rpm, room temperature). After this time, the solution appeared homogeneous. For comparative purposes, a liquid electrolyte was prepared according to the same procedure by using N,N- dimethyltrifluoromethane-sulfonamide (TFSA11) instead of N,N- dimethyldifluoromethane sulfonamide (DFSA11). The weight and volume ratio between sulfonamide and lithium salt was the same in both cases (88/12).

The final electrolyte compositions are the following: Component wt%

A, A-dimethyltrifluoromethane-sulfonamide (TFSA11) or

88 A-dimethyldifluoromethane-sulfonamide (DFSA11)

LiFSI 12

The ionic conductivity was measured by AC impedance spectroscopy using two-pole immersion cells (CDC749, Hach Lange sensors, Radiometer Analytical) at RT and a LiFSI concentration of IM.

From the table above, it can be seen that when the electrolyte comprises N,N- dimethyldifluoromethane sulfonamide the ionic conductivity is higher than when the electrolyte comprises A A-dimethyltrifluoromethane sulfonamide.

Example 3: TGA measurements

Thermogravimetric analysis (TGA) was carried out on Netzsch STA 449 F3 system. The experiments were performed under an argon flow at a heating rate of 10 °C min'¹ from room temperature up to 600 °C.

Example 4: LillLi cell resistance and galvanostatic cycling

The interfacial resistance at the interface between the electrolyte and the Li metal electrode was characterized by Li-symmetric cells using Celgard 2500 as separator in CR2032 type cells. Previously prepared electrolyte solution according to Example 2 was cast on the separator and the cell was closed with a crimper inside an Argon filled glovebox. Electrochemical impedance spectra (EIS) of the cells were recorded in the range from 10⁶ to 10^-2 Hz at 25 °C using a VMP3 potentiostat (Biologic). Next, galvanostatic cycling of Li- symmetric cells (area of Li metal disk: 1.54 cm²) was carried out using Neware battery testers keeping a constant total capacity of 1 mAh cm’² and varying the current density from C/20 up to 1C.

Claims

1.- A liquid electrolyte comprising: i. at least one sulfonamide with general formula I

I wherein Ri and R2 are independently selected from a linear or branched C1-C12 alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), a Ce- C12 aryl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH₂CH2O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 20; or Ri and R2 may be combined with each other to form a nitrogen-containing aliphatic ring; and ii. at least one lithium salt; being said electrolyte further characterized in that:

2.- The liquid electrolyte according to claim 1, wherein Ri and R2 in the at least one sulfonamide with general formula I are independently selected from a linear or branched C1-C12 alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH2CH2O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 10; or Ri and R2 may be combined with each other to form a 3- to 7- membered nitrogen-containing aliphatic ring.

3.- The liquid electrolyte according to any of claims 1 or 2, wherein Ri and R2 in the at least one sulfonamide with general formula I are selected, each independent on the other, from a linear Ci-Ce alkyl group, a C2-C6 alkenyl group, and -CH2CH2OCH2CH2O-CH3; or Ri and R2 may be combined with each other to form a 3- to 6-membered nitrogencontaining aliphatic ring.

4.- The liquid electrolyte according to any of the preceding claims, wherein the at least one sulfonamide represents from 5 to 95 wt.% of the weight of the electrolyte, preferably from 10 to 90 wt.% of the weight of the electrolyte, more preferably from 50 to 90 wt.% of the weight of the electrolyte; even more preferably, is about 88 wt.% of the weight of the electrolyte.

5.- The liquid electrolyte according to any of the preceding claims, wherein the at least one lithium salt is an organic or inorganic lithium salt selected from LiClO₄, LiNO₃, LiBF₄, LiAsF₆, LiPF₆, LiBF₃Cl, LiF, LiN(SO₂CF₃)₂, LiN(SO₂CF₃)(SO₂CF₂H), LiN(SO₂F)₂, LiN(SO₂CF₃)(SO₂F), LiN(C₂F₅SO₂)(SO₂F), LiB(C₂O₄)₂, LiBF₂(C₂O₄), LiC(SO₂CF₃)₃, LiPF₃(C₂F5)₃, LiCF₃SO₃ or a combination thereof; preferably, the at least one lithium salt is selected from LiN(SO₂CF₃)(SO₂CF₂H), LiB(C₂O₄)₂, LiN(SO₂F)₂, LiN(SO₂CF₃)₂, LiN(SO₂CF₃)(SO₂F) or a combination thereof; more preferably, the at least one lithium salt is LiN(SO₂F)₂.

6.- The liquid electrolyte according to any of the preceding claims, wherein the amount of the at least one lithium salt ranges from 5 to 25 wt.%, preferably from 8 to 18 wt.%, even more preferably from 10 to 15 wt.%, even more preferably is about 12 wt.% with respect to the total weight of the electrolyte.

7.- The liquid electrolyte according to any one of the preceding claims comprising: i. a sulfonamide of formula and ii. an organic lithium salt selected from LiN(SO₂CF₃)(SO₂CF₂H), LiN(SO₂F)₂, LiN(SO₂CF₃)₂, or a combination thereof; iii. optionally, a solvent, wherein the weight ratio between the sulfonamide and the organic lithium salt may vary from 80:20 to 95:5; being said electrolyte further characterized in that it does not further comprise a polymer.

8.- A method for preparing the liquid electrolyte of any of claims 1 to 7 comprising the steps of:

(i) providing at least one lithium salt;

(iii) when the first mixture is in solid form, adding to said mixture at least one solvent suitable for dissolving it, thus obtaining a second mixture; and

(iii) stirring the mixture from step (ii) or (iii).

9.- An electrochemical cell or battery comprising the electrolyte according to any of claims 1 to 7, a cathode, an anode, and, optionally, a separator.

10.- The electrochemical cell or battery according to claim 9 wherein the anode consists of lithium metal and the separator, if present, consists of a polypropylene membrane.

11.- A sulfonamide of formula I:

I wherein Ri and R2 are independently selected from a linear or branched C1-C12 alkyl group which may be substituted with one or more fluorine atom(s), a linear or branched C2-C12 alkenyl group which may be substituted with one or more fluorine atom(s), a Ce- C12 aryl group which may be substituted with one or more fluorine atom(s), and CH2CH2O-(CH₂CH2O)_n-R3, wherein R3 is a methyl or ethyl group and n is an integer from 0 to 20; or Ri and R2 may be combined with each other to form a nitrogen-containing aliphatic ring; provided that :

- Ri and R2 are not simultaneously ethyl; - Ri and R2 are not simultaneously -CH2-CEUCH2; and

- Ri is unsubstituted phenyl and R2 is methyl or viceversa.

12.- Use of the sulfonamide of formula I according to claim 11 in liquid electrolytes.

13.- Method of preparing the sulfonamide of formula I according to claim 11, wherein said method comprises adding a solution of a compound of formula la to a solution of a compound of formula lb

,^R1

H-N

R₂ lb . wherein Ri and R2 are as defined in claim 11.

14.- The method according to claim 13, wherein said method optionally further comprises purifying the so-obtained sulfonamide of formula I.

15.- Use of the electrochemical cell or battery according to any of claims 9 or 10 in electric motors; electric cars, including electric vehicles (EV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), or the like; electric carts, including electric bikes (E-bikes) and electric scooters (E-scooters); electric golf carts; or electric power storage systems.