Deep eutectic polymeric electrolytes with unipolar ionic conductivity

Abstract

Deep eutectic polymer electrolytes with unipolar ionic conductivity Unipolar eutectic polymer electrolyte, also called SI PDEE, comprising: - at least one polymer whose main chain is formed from monomers, M, in C2 to C20 ethylenically polymerizable with at least one, and preferably several, monomeric units of said main chain bearing at least one anionic group called SI-, - at least one hydrogen bond donor species, called HBD, in an SI-:HBD molar ratio varying from 1:0.5 to 1:15, in particular from 1:1 to 1:15; and - at least one alkali metal cation, X+.

Description

Title of the invention: Deep eutectic polymeric electrolytes with unipolar ionic conductivity technical field

[0001] The present invention relates to new deep eutectic polymeric electrolytes, also called eutectogels, which can be used as solid polymeric electrolytes.

[0002] Such electrolytes can be used in various electrochemical systems or devices, including lithium batteries, sodium batteries or potassium batteries. Previous technique

[0003] In a classical manner, the operating principle of an electrochemical generator is based on the insertion and withdrawal, also called "disinsertion", of an alkali metal ion or a proton, in and from the positive electrode, and the deposition or extraction of this ion, on and from the negative electrode.

[0004] The main systems use Li+, Na+ and / or K+ cations as transport ionic species. In the case of a lithium battery, for example, the Li+ cation extracted from the cathode during battery discharge is deposited on the anode, and conversely, it is extracted from the anode to be intercalated in the cathode during charging.

[0005] The transport of the proton or the alkali cation, in particular the lithium, sodium or potassium cation, between the cathode and the anode, is ensured by an ionically conductive electrolyte.

[0006] The formulation of the electrolyte used is essential for the performance of the electrochemical system, particularly when it is used at very low or very high temperatures. The ionic conductivity of the electrolyte, in particular, determines the efficiency of the electrochemical system since it affects the mobility of ions between the positive and negative electrodes.

[0007] Other parameters also come into play in the choice of the electrolyte used. These include its thermal, chemical or electrochemical stability within the electrochemical system, as well as economic, safety and environmental criteria, including in particular the toxicity of the electrolyte.

[0008] Generally speaking, the electrolytes of electrochemical systems are in liquid, gel or solid form.

[0009] Lithium batteries, sodium batteries and potassium batteries using solid-state electrolytes (also called "SSE" for the Anglo-Saxon acronym "Solid-State Electrolyte") make it possible to achieve energy densities higher temperatures and increased safety due to the absence of solvents. In particular, solid polymer electrolytes (also known as "SPEs" for "Solid Polymer Electrolytes") allow for the implementation of thinner batteries with greater flexibility.

[0010] Conventionally, the most common polymeric solid electrolytes consist of a polymer matrix in which an alkali metal salt, such as lithium, sodium, or potassium, is dissolved. Most polymer matrices are polyether matrices, and more specifically poly(ethylene oxide) (POE) and its derivatives, valued for their low glass transition temperature (Tg), on the order of -60°C, compared to other polymers, and their ability to complex Li+, Na+, and / or K+ cations. However, these electrolytes exhibit limited performance in terms of ion transport number (t+) and ionic conductivity due to the ion complexation mechanism. Thus, for a POE-based polymeric solid electrolyte, for example, the ion transport number t+ is generally low, on the order of 0.1 to 0.3.Furthermore, POE is largely crystalline (the crystallinity of pure POE is around 75-80% at room temperature), which leads to a loss of ionic conductivity of the POE-based solid electrolyte below its melting temperature (approximately 60-65°C).

[0011] It is known that the ionic conductivity at room temperature of polymer electrolytes can be improved by the addition of a conductive liquid phase, conventionally carbonate- or ether-based solvents: these are then called gelled electrolytes. This conductive liquid phase has a dual advantage: it itself participates in the conduction of Li+, Na+, and / or K+ cations and allows the polymer matrix to be plasticized, thus improving its ionic conductivity. Porcarelli et al. [1] notably describe the synthesis of gelled polymer electrolytes with unipolar conductivity, the matrix of which is composed of POE derivatives and the gelling agent is propylene carbonate. Although the ionic conductivity of gelled electrolytes is higher than that of solid polymer electrolytes, it remains low at room temperature, being below 0.7 mS / cm.

[0012] It has been considered that the transport number of Li+, Na+ and / or K+ cations can be improved by using an electrolyte in which only the Li+, Na+ and / or K+ cation is mobile, while the counter-anion, grafted onto the polymer matrix, is immobile. However, like conventional polymer electrolytes, unipolar polymer electrolytes suffer from low ionic conductivity at room temperature.

[0013] In fact, eutectogels, namely gelled electrolytes whose conductive liquid phase is composed of a "Deep Eutectic Electrolyte" or DEE, also Deep Eutectic Solvent (DES) has been proposed. Kelchterman et al. [2,3] describe the synthesis of eutectogels obtained by polymerization of a DES composed of LiTFSI, the monomer NMAC (N-methylacetamide), and various other monomers. Zhang et al. [4] describe the polymerization of a DES composed of a lithium salt and the monomer NIPAM (N-isopropylacrylamide) in the presence of a crosslinking agent and ethylene carbonate. However, these electrolytes contain a high amount of conductive liquid phase (DES), and the transport number of these electrolytes is not equal to 1.

[0014] Consequently and to the inventors' knowledge, there is no eutectogel electrolyte available to date that provides satisfactory unipolar ionic conductivity at room temperature, while also resolving the problems related to the safety of electrochemical systems.

[0015] The present invention is specifically designed to meet these expectations. Description of the invention

[0016] The invention thus relates to a unipolar ionic conductivity eutectic polymeric electrolyte, also called a single-ion eutectic gel or SI PDEE, comprising:

[0017] - at least one polymer whose main chain is formed from monomers, M, in C2 to C2o ethylenically polymerizable with at least one, and preferably several, monomeric units of said main chain bearing at least one anionic group called SI,

[0018] - at least one hydrogen bond donor species, called HBD, in a ratio molar SI:HBD varying from 1:0.5 to 1:15, in particular from 1:1 to 1:15; and

[0019] - at least one cation, X+, of alkali metal.

[0020] Thus, the inventors have found that it is possible to access a eutectic polymeric electrolyte with unipolar ionic conductivity leading to a satisfactory transport number subject to a specific choice of its precursor compounds.

[0021] Indeed, and as can be seen from the examples below, the unipolar ionic conductivity eutectic polymeric electrolytes according to the invention, also called single-ion eutectogels electrolytes according to the invention, advantageously possess, at a temperature of 30°C, an ionic conductivity greater than 6.4 105 S.cm1 as well as a transport number equal to 1 due to the unipolar ionic conductivity.

[0022] According to another aspect of it, the invention relates to a process for preparing a unipolar ionic conductivity eutectic polymer electrolyte according to the invention, comprising at least the step of polymerizing a eutectic electrolyte, referred to as SI DEE, which comprises at least one ethylenically polymerizable monomeric entity, and bearing at least one SI anionic group with an alkali counterion and at least one hydrogen bond donor species. HBD, in an SI:HBD molar ratio varying from 1:0.5 to 1:15, in particular from 1:1 to 1:15.

[0023] The invention also relates to a single-ion eutectic electrolyte, referred to as SI DEE, comprising at least one ethylenically polymerizable monomeric entity bearing at least one anionic group SI, in particular selected from sulfonimides and sulfonimidides, sulfonates, acetates, borates and their derivatives, with an alkali counter-ion in particular selected from Li, Na or K and at least one hydrogen bond donor species HBD comprising at least one amide, thioamide, carbamide, polyether, glyme, sulfone, sulfonamide, hydroxyl, carboxylic acid, nitrile, ketoester and / or heterocyclic group, in an SI:HBD molar ratio ranging from 1:0.5 to 1:15, in particular from 1:1 to 1:15, more preferably from 1:4 to 1:8, better a molar ratio of 1:6.

[0024] The invention also aims to protect an electrochemical system comprising at least one unipolar ionic conductivity eutectic polymer electrolyte SI PDEE according to the invention and / or obtained according to the process of the invention, said electrochemical system being more particularly a rechargeable battery, in particular a lithium-metal, lithium-ion, sodium-metal, sodium-ion, potassium-metal or potassium-ion battery.

[0025] In the following text, the expressions "between ... and ...", "ranging from ... to ..." and "varying from ... to ..." are equivalent and are meant to mean that the limits are included, unless otherwise stated. Brief description of the drawings

[0026] [Fig.1] presents a graph of the ionic conductivity (in S.cm1) as a function of temperature (in °C) and the inverse of temperature (in 1 / K) of the single-ion eutectogels electrolytes p(MTFSI-Li / NMAC10) and p(MTFSI-Li / NMAC6) according to the invention.

[0027] [Fig.2] presents a graph of ionic conductivity (in S.cm1) as a function of the temperature (in °C) and the inverse of the temperature (in 1 / K) of the single-ion eutectogels electrolytes p(STFSLLi / NMAC6) and p(MTFSLLi / DMEU6).

[0028] [Fig.3] presents a graph of ionic conductivity (in S.cm1) as a function of the temperature (in °C) and the inverse of the temperature (in 1 / K) of the eutectogels electrolytes p(MTFSI-Li / SO6) and p(MTFSI-Li / DMMSA6).

[0029] [Fig.4] presents a graph of ionic conductivity (in S.cm1) as a function of the temperature (in °C) and the inverse of the temperature (in 1 / K) of the eutectogels electrolytes p(MTFSI-Li / DMPU6) and p(MTFSI-Li / TMU6). Detailed description

[0030] UNIPOLAR IONIC CONDUCTIVITY EUTECTIC POLYMERIC ELECTROLYTE

[0031] As mentioned previously, the electrolytes according to the invention, referred to as single-ion eutectogels, comprise:

[0032] - at least one polymer whose main chain is formed from monomers, M, in C2 to C2o ethylenically polymerizable with at least one, and preferably several, monomeric units of said main chain bearing at least one anionic group called SI,

[0033] - at least one hydrogen bond donor species, called HBD, in a ratio molar SI:HBD varying from 1:0.5 to 1:15, in particular from 1:1 to 1:15; and

[0034] - at least one cation, X+, of alkali metal.

[0035] In the context of the invention, the following definitions apply:

[0036] - "eutectic solvent" or "DES", a solvent composed of two or more constituents capable of self-association, particularly via the formation of strong hydrogen bonds, to form a eutectic mixture with a melting point lower than that of each constituent taken individually. Generally, DESs are composed of a mixture of two or more constituents, usually at least one hydrogen bond donor (HBD) species with at least one hydrogen bond acceptor (HBA) species, in proportions corresponding to the eutectic point of said mixture.

[0037] - "deep eutectic polymeric electrolyte" or "eutectogel electrolyte", a electrolyte formed from a polymer matrix containing a DES (or DEE) composed of at least one alkali metal salt and at least one HBD,

[0038] - "electrolyte with unipolar ionic conductivity", or "single-ion" (single-ion), an electrolyte in which only the Li+, Na+ and / or K+ cation is mobile, while the counter-anion is grafted onto a polymer matrix or a polymer chain, and therefore does not participate in ionic conductivity,

[0039] - "ethylenically polymerizable monomer", a monomer comprising at a C=C unsaturation reactive to polymerization,

[0040] - "hydrogen bond donor species" or "HBD", a species capable of to dissociate the ionic bond between the counter-anion and the alkali metal cation,

[0041] - "alkali metal", a chemical element in the first column of the table periodic table of elements, and more specifically lithium, sodium, potassium, rubidium, cesium.

[0042] The hydrogen bond-donating species HBD considered according to the invention is a compound known to form a DES or DEE with an alkali metal salt. As such, it is further designated according to the invention as a precursor of the deep eutectic solvent SI DES and of the polymer electrolyte SI PDEE.

[0043] The polymer composing a single-ion eutectogel electrolyte according to the invention comprises a main chain formed from monomers, M, in C2 to C2o ethylenically polymerizable with at least one, and preferably several, monomeric units of said main chain bearing(s) at least one anionic group said SI.

[0044] In particular, this or these ethylenically polymerizable monomer(s) M, from which this polymer is derived, comprise at least one polymerizable function of the type (meth)acrylate, (meth)acrylamide, in particular N-alkylacrylamide, vinylaryl, or allylaryl; preferably (meth)acrylate, in particular propylene (meth)acrylate, or vinylbenzyl, in particular vinylbenzylene.

[0045] According to a particularly preferred embodiment, the electrolyte comprises at least one polymer comprising several identical or different units of the following general formula (I): R 1 R 2

[0046] in which:

[0047] - R1 and R2 independently represent a hydrogen or a hydrocarbon group in Ci to C4;

[0048] - n is an integer greater than or equal to 2, in particular from 10 to 5000;

[0049] - features a simple bond between SI and the hydrocarbon chain or a organic spacer E as defined below;

[0050] - SI denotes a single-ion anionic group, and is derived from anions selected from sulfonimides and sulfonimidides, sulfonates, acetates, borates and their derivatives;

[0051] - HBD designates a hydrogen bond donor species, in particular comprising at least one amide, thioamide, carbamide, polyether or glyme function, in particular diglyme, triglyme, tetraglyme, pentaglyme and hexaglyme, sulfone, sulfonamide, hydroxyl, carboxylic acid, nitrile, ketoester and / or a heterocyclic group;

[0052] - X is an alkali metal Li, Na or K, preferably is Li.

[0053] The substituents R1 and R2, if they represent a hydrocarbon group, preferably represent a methyl group.

[0054] Preferably, n in the aforementioned formula (I) can be between 10 and 3,000, in particular between 10 and 1,000.

[0055] The organic spacer E may comprise from 2 to 8 carbon atoms, be saturated or unsaturated, linear, cyclic or aromatic, optionally interrupted by one or more heteroatom(s), in particular S, O, N, or by C(O), and for example be a phenylene or an alkyl ester.

[0056] According to one embodiment, the compound according to the invention is devoid of spacer E.

[0057] According to another embodiment, the compound according to the invention comprises a spacer E in particular selected from phenylenes and alkyl esters which comprise from 1 to 4 carbon atoms.

[0058] The SI:X+ motif of the general formula (I) may include in particular a lithium / sodium / potassium sulfonimide, a lithium / sodium / potassium sulfonimidide, a lithium / sodium / potassium sulfonate, a lithium / sodium / potassium acetate, in particular a lithium / sodium / potassium trifluoroacetate, or a lithium / sodium / potassium borate.

[0059] According to one embodiment, all the SI .. .HBD...X+ motifs constituting the polymer of the electrolyte of the invention are identical.

[0060] According to another embodiment, the electrolyte polymer according to the invention has at least different SI motifs and different X+ metal cations.

[0061] Preferably, the anionic group(s) SI is derived from anion(s) selected from bis(trifluoromethanesulfonyl)imidide TFSI, bis(pentafluoroethane sulfone)imidide BETI, bis(fluorosulfonyl)imidide FSI, trifluoromethane sulfonate TfO, trifluoroacetate TFA, preferably the anionic group SI is derived from TFSI, more preferably is the sulfonylene anion of (trifluoromethylsulfonyl)azanide.

[0062] The hydrogen bond donor species HBD comprises at least one amide function, in particular N-alkylamide, thioamide, carbamide, polyether or glyme in particular diglyme, triglyme, tetraglyme, pentaglyme and hexaglyme, sulfone, sulfonamide, hydroxyl, carboxylic acid in particular alpha-carboxylic acid, nitrile in particular dinitrile, ketoester and / or a heterocyclic group such as pyridine and its derivatives, in particular alkylpyridines and lactones, in particular alpha-lactones, beta-lactones, gamma-lactones, delta-lactones and omega-lactones.

[0063] By way of example, the HBD species may be chosen from acetamide AA, N-methylacetamide NMAC, dimethylacetamide DMAC, propanamide PA, butanamide BA, urea U, methylurea MU, ethylurea EU, dimethylurea DMU, ​​tetramethylurea TMU, 2,2,2-trifluoroacetamide TFAA, rimidazolidinone I, l,3-dimethyl-2-imidazolidinone DMI, l,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone DMPU, thiourea SU, dimethoxyethane, diglyme (2,5,8-trioxanonane), triglyme (2,5,8,11-tetraoxadodecane), tetraglyme (2,5,8,11,14-pentaoxapentadecane), pentaglyme (2,5,8,11,14,17-hexaoxaoctadecane), hexaglyme (2,5,8,11,14,17,20-heptaoxahenicosane), methanesulfonamide MSA, N,N-dimethylmethanesulfonamide DMMSA, dimethylsulfone MSM, glycerol G, ethylene glycol EG, lactic acid LA, oxalic acid OA, succinonitrile SN, methyl pyruvate MP, methyl acetoacetate MA, methyl levulinate ML, 2-ethylpyridine EP, gamma-butyrolactone GBL.

[0064] The HBD species is preferably selected from N-methylacetamide NMAC, succinonitrile SN, dimethylacetamide DMAC, sulfolane SO, N,N-dimethylmethanesulfonamide DMMSA, tetramethylurea TMU, l,3-dimethyl-2-imidazolidinone DMEU, l,3-dimethyl-3,4,5,6-tetrahydro-2(lH)-pyrimidinone DMPU, and mixtures thereof.

[0065] In particular, the electrolyte contains at least one anionic SI group and at least one hydrogen bond donor species HBD in an SI:HBD molar ratio ranging from 1:1 to 1:15, more preferably from 1:4 to 1:8, better a molar ratio of 1:6.

[0066] According to a particular embodiment,

[0067] - said monomer M ethylenically polymerizable precursor of said polymer includes at least one polymerizable (meth)acrylate type function, and:

[0068] - the anionic SI group is derived from TFSI and the bond-donating species HBD hydrogen is NMAC, DMAC, SN, SO, DMMSA, TMU, DMEU, or DMPU in an SI:HBD molar ratio of 1:6, or

[0069] - the anionic SI group is derived from TFSI and the bond-donating species hydrogen HBD is the NMAC in an SI:NMAC molar ratio of 1:10, or

[0070] - the ethylenically polymerizable monomer M comprises at least one function polymerizable of the vinylbenzyl type and the anionic group SI is derived from TFSI and the hydrogen bond donor species HBD is NMAC in an SI:NMAC molar ratio of 1:6.

[0071] Advantageously, the electrolyte comprises at least one polymer made up of identical or different motifs of general formula (I) described above. PREPARATION METHODS

[0072] As stated above, another aspect of the present invention relates to a useful process for preparing single-ion eutectogels electrolytes according to the invention.

[0073] This process includes at least the step of polymerizing a eutectic electrolyte called SI DEE, said SI DEE comprising:

[0074] - at least one ethylenically polymerizable monomer M and carrying at least one anionic SI group with an alkali counter-ion, and

[0075] - at least one hydrogen bond donor species HBD, in a molar ratio SI:HBD varying from 1:0.5 to 1:15, in particular from 1:1 to 1:15.

[0076] The M monomers or ethylenically polymerizable monomeric entities may be selected from entities comprising at least one polymerizable function of the type (meth)acrylate, (meth)acrylamide, in particular N-alkylacrylamide, vinylaryl, or allylaryl; preferably (meth)acrylate or vinylbenzyl; more preferably (meth)acrylate of propylene or vinylbenzylene.

[0077] The term "alkaline counter-ion" designates an alkali cation, preferably the Li+, Na+ or K+ cation, more preferably the alkali counter-ion is Li+.

[0078] The anionic group SI and the species HBD are as described previously.

[0079] According to one embodiment, the SI DEE comprises at least the

[0080] 3-(2-methylprop-2-enoyloxy)propylsulfonyl-(trifluoromethylsulfonyl)azanide of lithium (MTFSLLi) and at least one HBD hydrogen bond donor species selected from NMAC, DMAC, SN, SO, DMMSA, TMU, DMEU or DMPU in an MTFSLLBD molar ratio of 1:6 or 1:10.

[0081] According to another embodiment, the SI DEE comprises at least lithium 4-vinyl-n-(trifluoromethane)sulfonylbenzene-l-sulfonamide (STFSLLi) and at least NMAC as a hydrogen bond donor species HBD in an STFSLNMAC molar ratio of 1:6.

[0082] In particular, the single-ion eutectic electrolyte known as SI DEE can be characterized in that: - the anionic SI group is derived from TFSI and the hydrogen bond-donating species HBD is NMAC, DMAC, SN, SO, DMMSA, TMU, DMEU or DMPU in an SI:HBD molar ratio of 1:6, or - the anionic group SI is derived from TFSI and the hydrogen bond donor species HBD is NMAC in an SI:NMAC molar ratio of 1:10.

[0083] As regards the polymerization, it is radical.

[0084] The experimental conditions to be retained for polymerization vary according to the chemical nature of the monomer, the anionic SI groups and the hydrogen bond donor species HBD retained.

[0085] These conditions generally fall within the skills of a person skilled in the art.

[0086] This polymerization can be activated by heat treatment, under UV radiation, in the presence or absence of a radical initiator.

[0087] A person skilled in the art may use any radical polymerization initiator conventionally used in reversible addition-fragmentation chain transfer (RAFT) radical polymerization, atom transfer radical polymerization (ATRP) radical polymerization, and nitroxide-mediated radical polymerization (NMP) radical polymerization.

[0088] Examples of radical initiators include (dia)azoic acids such as azobisisobutyronitrile, 4,4'-Azobis (4-cyanopentanoic acid) (or ACP), 1,10-azobis (cyclohexanecarbonitrile) (or VAZO-88), 2,2'-azobis (N-butyl-2-methylpropionamide) (or VAm-110), and 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide] (or VA-086), peroxides, persulfates such as K₂S₂O₈, boranes such as triethylborane, and mixtures thereof. More specifically, they may be selected from azobisisobutyronitrile, benzoyl peroxide, lauroyl peroxide, and mixtures thereof.

[0089] Polymerization can take place at a temperature ranging from 40 to 100°C, preferably from 60 to 80°C, more preferably from 65 to 85°C, better at a temperature of 70°C.

[0090] It can last from a few minutes to 10 hours, preferably from 30 minutes to 5 hours, more preferably from 45 minutes to 3 hours, better from 1 hour to 2 hours.

[0091] Preferably, the polymerization is carried out without a solvent medium.

[0092] According to one embodiment, the process may include, prior to polymerization, the formation of SI DEE by a process comprising at least the steps of:

[0093] - possess at least one ethylenically polymerizable monomeric entity and bearing at least one anionic group SI with an alkali counter-ion X+, called MSIX+ and

[0094] - to bring said monomeric entity MSIX+ into contact with at least one species hydrogen bond donor, HBD, precursor of a DES or DEE eutectic electrolyte, the amounts of MSIX+ monomeric entities and hydrogen bond donor species being adjusted to form an SI DEE with an SI:HBD molar ratio varying from 1:0.5 to 1:15, in particular from 1:1 to 1:15, more preferably from 1:4 to 1:8, better a molar ratio of 1:6.

[0095] In particular, the monomeric entity comprises at least one polymerizable function of the (meth)acrylate type, in particular propylene (meth)acrylate, or vinylbenzyl type, in particular vinylbenzylene.

[0096] In particular, the monomeric entity is functionalized by at least one SI anion derived from anions selected from sulfonimides and sulfonimidides, sulfonates, acetates, borates and their derivatives, and preferably from bis(trifluoromethanesulfonyl)imidide TFSI, bis(pentafluoroethane sulfone)imidide BETI, bis(fluorosulfonyl)imidide FSI, trifluoromethane sulfonate TfO, trifluoroacetate TFA.

[0097] In particular, the hydrogen bond donor species HBD is selected from species comprising at least one amide, thioamide, carbamide, polyether or glyme function, in particular diglyme, triglyme, tetraglyme, pentaglyme and hexaglyme, sulfone, sulfonamide, hydroxyl, carboxylic acid, nitrile, ketoester and / or heterocyclic group, and preferably from N-methylacetamide NMAC, succinonitrile SN, dimethylacetamide DMAC, sulfolane SO, N,N-dimethylmethanesu Ifonamide DMMSA, tetramethylurea TMU, l,3-dimethyl-2-imidazolidinone DMEU, l,3-dimethyl-3,4,5,6-tetrahydro-2(lH)-pyrimidinone DMPU, and mixtures thereof.

[0098] The interaction between the monomer and the hydrogen bond donor species is generally carried out without a solvent medium, and usually at room temperature, under stirring. It can last from a few minutes to 10 hours, preferably from 15 minutes to 5 hours, more preferably from 30 minutes to 3 hours, better from 45 minutes to 2 hours, even better 1 hour.

[0099] Of course, it is up to a person skilled in the art to adjust the preparation conditions of the single-ion eutectogel electrolyte and the SI DEE to obtain the desired compounds.

[0100] It should be noted that the single-ion eutectogel electrolyte according to the invention and / or obtained by the process of the invention, as well as the SI DEE electrolyte, are particularly safe to use as electrolytes. Indeed, the SI DEE electrolyte exhibits greater safety and / or security compared to liquid electrolytes known in the prior art, since it is less prone to the risk of auto-ignition. Moreover, once the SI DEE has been polymerized to give the single-ion eutectogel electrolyte according to the invention, safety and / or security are increased due to the solid nature of the polymeric electrolyte.

[0101] Furthermore, the single-ion eutectogel electrolyte according to the invention and / or obtained with the process of the invention, as well as the SI DEE electrolyte, are and remain homogeneous, in In addition to being easy to synthesize, no heterogeneous phases are obtained during their synthesis. Furthermore, they are obtained rapidly. APPLICATIONS

[0102] SI DEE and in particular the eutectogel single-ion electrolyte according to the invention can advantageously be used as electrolytes, in particular in an electrochemical system, in particular in a lithium, sodium or potassium battery.

[0103] As can be seen from the examples below, the eutectic polymeric electrolytes according to the invention advantageously possess a unipolar ionic conductivity at 30 °C greater than or equal to 6.4 105 S / cm, and as such, improved compared to eutectogels of the prior art.

[0104] Advantageously, a eutectic polymeric electrolyte according to the invention further exhibits a transport number at 30 °C equal to 1.

[0105] According to an advantageous embodiment, a eutectic polymeric electrolyte according to the invention thus has a unipolar ionic conductivity at 30 °C greater than or equal to 6.4 105 S / cm and a transport number at 30 °C equal to 1.

[0106] The unipolar ionic conductivity eutectic polymeric electrolyte according to the invention can be implemented in an electrochemical system.

[0107] The present invention thus relates, according to yet another of its aspects, to an electrochemical system comprising a eutectic polymer electrolyte with unipolar ionic conductivity as described above and / or obtained according to the preparation process as described above.

[0108] The electrochemical system can be an electrochemical generator, converter or storage system.

[0109] This may more specifically be a primary or secondary battery, for example a lithium, sodium or potassium battery.

[0110] According to a particular embodiment, the eutectic polymeric electrolyte is used in a battery, in particular a lithium battery.

[0111] The SI DEE electrolyte as described above can also be implemented in an electrochemical system.

[0112] According to another aspect of it, the invention thus relates to an electrochemical system comprising a single-ion eutectic electrolyte called SI DEE as described above and / or obtained according to the preparation process as described above.

[0113] The invention will now be described by means of the following examples, given of course by way of illustration and not limitation of the invention. Examples Example 1

[0114] Preparation of a deep eutectic polymer electrolyte p(MTFSI-Li / NMAC) with unipolar ionic conductivity

[0115] a) 0.45 g of MTFSI-Li (1 eq.) as the single-ion monomer (SIM) and 0.57 g of NMAC (6 eq.) as the hydrogen bond donor (HBD) are introduced into a vial equipped with a magnetic stirrer. The mixture is stirred for 1 hour at room temperature to form the MTFSLLi / NMAC (1:6) single-ion deep eutectic electrolyte monomer as a translucent, homogeneous, orange liquid.

[0116] b) 2.25 mg (0.5% by weight relative to MTFSLLi) of AIBN are added to the MTFSLLi / NMAC (1:6) monomer formed in a). The reaction mixture is stirred for 30 minutes until the AIBN is solubilized. The vial is then oven-heated at 70°C for 2 hours. The deep eutectic electrolyte polymer with unipolar ionic conductivity is obtained as a ductile, homogeneous, translucent, orange polymer. Example 2

[0117] Preparation of a deep eutectic polymer electrolyte p(MTFSI-Li / NMAC io ) with unipolar ionic conductivity

[0118] a) 0.35 g of MTFSLLi (1 eq.) as the single-ion monomer (SIM), and 0.74 g of NMAC (10 eq.) as the hydrogen bond donor (HBD), are introduced into a vial equipped with a magnetic stirrer. The mixture is stirred for 1 hour at room temperature, and the deep, single-ion eutectic electrolyte monomer is obtained as a translucent, homogeneous, orange liquid.

[0119] b) 1.75 mg (0.5% by weight relative to MTFSLLi) of AIBN are added to the MTFSLLi / NMAC (1:10) monomer formed in a). The reaction mixture is stirred for 30 minutes until the AIBN is solubilized. The vial is then oven-heated at 70°C for 2 hours. The deep eutectic electrolyte polymer with unipolar ionic conductivity is obtained as a ductile, homogeneous, translucent, orange polymer.

[0120] This polymer is more ductile than the polymer obtained in Example 1. Example 3

[0121] Characterization of the electrochemical properties of electrolytes

[0122] The ionic conductivity of the polymer electrolytes p(MTFSLLi / NMAC6) and p(MTFSLLi / NMACio) prepared in Examples 1 and 2 is determined by electrochemical impedance spectroscopy (EIS), using an impedance analyzer VMP3 (BioLogic) for a temperature range from 10°C to 80°C in 10°C increments.

[0123] To do this, each of them is introduced into a symmetrical button cell between two stainless steel blocking electrodes.

[0124] The ionic conductivity values ​​(o) of the two polymer electrolytes with unipolar ionic conductivity (transport number equal to 1) are presented in the following table 1.

[0125] [Tables 1] Electrolyte polymer o“ (S.cm1) p(MTFSI-Li / NMAC6) i,no4 p(MTFSI-Li / NMAC10) 7.1104

[0126] “measured at 30 °C.

[0127] Fig. 1 represents the evolution of the ionic conductivity of the electrolytes p(MTFSLLi / NMAC6) and p(MTFSLLi / NMACio) as a function of temperature.

[0128] It is thus observed that the electrolytes p(MTFSLLi / NMAC6) and p(MTFSLLi / NMAC io) according to the invention have interesting unipolar ionic conductivity values ​​at 30°C and these over a temperature range from 10 °C to 80 °C.

[0129] Moreover, they both allow a transport number equal to 1. Example 4

[0130] Preparation of DEE deep eutectic electrolytes with unipolar ionic conductivity according to the invention from various hydrogen bond donors and their electrochemical characterization

[0131] A defined mass of single-ion monomer MSI (MTFSLLi or STFSLLi) and a defined mass of hydrogen bond-donating species HBD are introduced into a vial equipped with a magnetic stirrer, in a molar ratio of 1:6 MSI HBD. The mixture is stirred for 1 hour at room temperature, and the deep single-ion eutectic electrolyte monomer, denoted SI DEE, is obtained.

[0132] The mass percentages and masses of the MSI and HBD used are specified respectively in Tables 2 and 3 below.

[0133] [Tables2] Single-ion monomers MSI Hydrogen bond donors, HBD % • / mass volume MTFSI -Li STFSI -Li DMA C SO DMMS A TMU DME U DMPU NMA C SI DEE 1 0.4 - 0.60 - - - - - - SI DEE 2 0.33 - - 0.68 - - - - - SI DEE 3 0.32 - - - 0.68 - - - - SI DEE 4 0.33 - - - - 0.67 - - - SI DEE 5 0.33 - - - - - 0.67 - - SI DEE 6 0.31 - - - - - - 0.69 - SI DEE 7 0.44 - - - - - - - 0.56 SI DEE 8 - 0.44 - - - - - - 0.56

[0134] [Tables3] Single-ion monomers MSI Hydrogen bond donors, HBD Masses (g) MTFSI -Li STFSI -Li DMAC so DMMSA TMU DME U DMPU NMA C SI DEE 1 0.40 - 0.61 - - - - - - SI DEE 2 0.33 - - 0.69 - - - - - SI DEE 3 0.35 - - - 0.75 - - - - SI DEE 4 0.33 - - - - 0.67 - - - SI DEE 5 0.35 - - - - - 0.69 - - SI DEE 6 0.31 - - - - - - 0.69 - SI DEE 7 0.45 - - - - - - - 0.57 SI DEE 8 - 0.45 - - - - - - 0.61

[0135] After addition of radical initiator (AIBN) and heat treatment, the eutectic electrolyte polymers with unipolar ionic conductivity corresponding to each SI DEE are obtained.

[0136] Their ionic conductivity is determined by electrochemical impedance spectroscopy as described in Example 3.

[0137] The ionic conductivity values ​​(o) of the different polymer electrolytes with unipolar ionic conductivity (transport number equal to 1) synthesized are gathered in the following table 4.

[0138] This table also reports, as witnesses, the ionic conductivity values ​​(o) of electrolytes not in accordance with the invention, namely the electrolytes obtained in the prior art by Porcarelli et al. [1], and Kelchtermans et al. [2].

[0139] [Tables4] Polymer electrolyte o“ (S.cm1) 1 p(MTFSI-Li / DMAC6) i,no4 2 p(MTFSI-Li / SO6) 1.2104 3 p(MTFSI-Li / DMMSA6) 1.1104 4 p(MTFSI-Li / TMU6) 9.6105 5 p(MTFSI-Li / DMEU6) 7.2105 6 p(MTFSI-Li / DMPU6) 6.4105 7 p(MTFSI-Li / NMAC6) 1.1104 8 p(STFSI-Li / NMAC6) 1.3104 Porcarelli et al. [1] SIPE3 (p(MTFSI-LI / PEGM / PEGDM) + 50%m PC) 7.105 Kelchtermans et al. P-ETG-70 (p(NIPAM-EGDMA) + 70% N-MAC / Li TFSI) 1.104

[0140] “measured at 30 °C.

[0141] PEGM: poly(ethylene glycol) methyl ether methacrylate,

[0142] PEGDM: bifunctional poly(ethylene glycol) methyl ether dimethacrylate,

[0143] PC: propylene carbonate,

[0144] P-ETG-70: eutectogel with a polymer skeleton containing 70% vol of DES,

[0145] NIPAM: N-Isopropylacrylamide,

[0146] EGDMA: ethylene glycol dimethacrylate.

[0147] Figures 2, 3 and 4 represent the evolution of the ionic conductivity of polymer electrolytes 2 to 8 as a function of temperature.

[0148] It is thus observed that all the eutectic polymer electrolytes with unipolar ionic conductivity according to the invention offer advantages over prior art electrolytes. The single-ion eutectogels of the invention have ionic conductivity values ​​at 30°C of the same order or higher than that of the electrolyte of Porcarelli et al., while offering the considerable advantage of not using a carbonate solvent, which would introduce problems related to the lack of electrolyte safety.

[0149] Although the single-ion eutectogels according to the invention have ionic conductivity values ​​at 30°C of the same order as that of the electrolyte of Kelchtermans et al., they allow a transport number (tLi+) equal to 1 due to the unipolar conductivity. The conductivity of Li+ (oLi+, where oLi+ = o * tLi+) of the single-ion eutectogels of the invention is therefore significantly higher than that of Kelchtermans et al. List of documents cited

[0150] [1] Porcarelli L, Shaplov AS, Bella F, Nair JR, Mecerreyes D, Gerbaldi C. Single- Ion Conducting Polymer Electrolytes for Lithium Metal Polymer Batteries that Operate at Ambient Temperature. ACS Energy Lett 2016;1:678-82. https: / / doi.org / 10.1021 / ac senergy lett. 6b00216.

[0151] [2] Kelchtermans AS, Joos B, De Sloovere D, Paulus A, Mercken J, Mylavarapu SK, et al. Polymeric Backbone Eutectogel Electrolytes for High-Energy Lithium-Ion Batteries. ACS Oméga 2023; 8:36753-63. https: / / doi.org / 10.1021 / acsomega.3c03081.

[0152] [3] Kelchtermans A-S, Joos B, De Sloovere D, Mercken J, Derveaux E, Adriaensens P, et al. How Polymer Influences the Electrochemical Behavior of Eutectogels for Lithium Batteries. ACS Appl Polym Mater 2024;6:90-101. https: / / doi.org / 10.1021 / acsapm.3c01487.

[0153] [4] Zhang C, Niu Z, Bae J, Zhang L, Zhao Y, Yu G. Polyeutectic-based stable and effective electrolytes for high-performance energy storage Systems. Energy Environ Sci 2021;14:931-9. https: / / doi.org / 10.1039 / D0EE03100C.

Claims

1.

2.

3. Demands Unipolar ionic conductivity eutectic polymeric electrolyte, also known as SI PDEE, comprising: - at least one polymer whose main chain is formed from monomers, M, in C2 to C2o ethylenically polymerizable with at least one, and preferably several, monomeric units of said main chain bearing(s) at least one anionic group called SI, - at least one hydrogen bond-donating species, known as HBD, in an SI:HBD molar ratio ranging from 1:0.5 to 1:15, in particular from 1:1 to 1:15; and - at least one cation, X+, of alkali metal. Electrolyte according to the preceding claim, characterized in that said hydrogen bond donor species HBD is a precursor of deep eutectic solvent called DES. Electrolyte according to claim 1 or 2, characterized in that said polymer comprises several identical or different motifs of the following general formula (I): in which: - R1 and R2 independently represent a hydrogen or a hydrocarbon group in Ci to C4; - n is an integer greater than or equal to 2, in particular ranging from 10 to 5000; represents a simple link between SI and the chain hydrocarbon or an organic spacer E, in particular E comprises from 2 to 8 carbon atoms, is saturated or unsaturated, linear, cyclic or aromatic, optionally interrupted by a or several heteroatom(s), in particular S, O, N, or by C(O), and for example is a phenylene or an alkyl ester; - SI denotes a single-ion anionic group, and is derived from anions selected from sulfonimides and sulfonimidides, sulfonates, acetates, borates and their derivatives; - HBD denotes a hydrogen bond-donating species, in particular comprising at least one amide, thioamide, carbamide, polyether or glyme function, in particular diglyme, triglyme, tetraglyme, pentaglyme and hexaglyme, sulfone, sulfonamide, hydroxyl, carboxylic acid, nitrile, ketoester and / or a heterocyclic group; - X is an alkali metal Li, Na or K, preferably is Li.

4. Electrolyte according to any one of the preceding claims, characterized in that said hydrogen bond donor species HBD is selected from N-methylacetamide NMAC, succinonitrile SN, dimethylacetamide DMAC, sulfolane SO, N,N-dimethylmethanesulfonamide DMMSA, tetramethylurea TMU, 1,3-dimethyl-2-imidazolidinone DMEU, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone DMPU, and mixtures thereof.

5. Electrolyte according to any one of the preceding claims, characterized in that the anionic group(s) SI is derived from anion(s) selected from bis(trifluoromethanesulfonyl)imidide TFSI, bis(pentafluoroethane sulfone)imidide BETI, bis(fluorosulfonyl)imidide FSI, trifluoromethane sulfonate TfO, trifluoroacetate TFA, preferably the anionic group SI is derived from TFSI, more preferably is the sulfonylene anion of (trifluoromethyl 1s ulfony 1) azanide.

6. Electrolyte according to any one of the preceding claims, characterized in that said ethylenically polymerizable monomer M comprises at least one polymerizable function of the type (meth)acrylate, (meth)acrylamide, in particular N-alkylacrylamide, vinylaryl, or allylaryl; preferably (meth)acrylate or vinylbenzyl; more preferably (meth)acrylate of propylene or vinylbenzylene.

7. Electrolyte according to any one of the preceding claims, characterized in that it contains at least one anionic SI group and at least one hydrogen bond donor species HBD in an SI:HBD molar ratio ranging from 1:1 to 1:

15.

8. Electrolyte according to any one of the preceding claims, characterized in that said ethylenically polymerizable monomer M comprises at least one polymerizable function of the (meth)acrylate type, and: - the anionic group SI is derived from TFSI and the hydrogen bond donor species HBD is NMAC, DMAC, SN, SO, DMMSA, TMU, DMEU or DMPU in an SI:HBD molar ratio of 1:6, or - the anionic group SI is derived from TFSI and the hydrogen bond donor species HBD is NMAC in an SI:NMAC molar ratio of 1:10; or else said ethylenically polymerizable monomer M comprises at least one polymerizable function of the vinylbenzyl type and the anionic group SI is derived from TFSI and the hydrogen bond donor species HBD is NMAC in an SI:NMAC molar ratio of 1:

6.

9. A method for preparing a unipolar ionic conductivity eutectic polymer electrolyte according to any one of the preceding claims, comprising at least the step of polymerizing a eutectic electrolyte, referred to as SI DEE, which comprises at least one ethylenically polymerizable monomeric entity, and bearing at least one SI anionic group with an alkali counterion and at least one HBD hydrogen bond-donating species, in an SI:HBD molar ratio ranging from 1:0.5 to 1:

15.

10. A process according to the preceding claim, said polymerization being activated by heat treatment under UV radiation, in the presence or not of a radical initiator.

11. A process according to any one of claims 9 to 10, said SI DEE being first obtained by a process comprising at least the steps of: - having at least one ethylenically polymerizable monomeric entity bearing at least one anionic SI group with an alkali counterion X+, said MSIX+, and - bringing said monomeric entity MSI X+ into contact with at least one hydrogen bond-donating species, HBD, precursor of a DES or DEE eutectic electrolyte, in a molar ratio of SI :HBD varying from 1:0.5 to 1:15, in particular from 1:1 to 1:15, to form a eutectic electrolyte called SI DEE.

12. A method according to any one of claims 9 to 11, said anionic group SI being as defined in claim 5 and said hydrogen bond donor species HBD being as defined in claim 4.

13. Single-ion eutectic electrolyte referred to as SI DEE, comprising at least one ethylenically polymerizable monomeric entity bearing at least one anionic SI group, in particular selected from sulfonimides and sulfonimidides, sulfonates, acetates, borates and their derivatives, with an alkali counterion in particular selected from Li, Na or K and at least one hydrogen bond donor species HBD comprising at least one amide, thioamide, carbamide, polyether, glyme, sulfone, sulfonamide, hydroxyl, carboxylic acid, nitrile, ketoester and / or heterocyclic group, in an SI:HBD molar ratio ranging from 1:0.5 to 1:15, in particular from 1:1 to 1:

15.

14. Single-ion eutectic electrolyte referred to as SI DEE according to claim 13, characterized in that: - the anionic group SI is derived from TFSI and the hydrogen bond donor species HBD is NMAC, DMAC, SN, SO, DMMSA, TMU, DMEU or DMPU in an SI:HBD molar ratio of 1:6, or - the anionic group SI is derived from TFSI and the hydrogen bond donor species HBD is NMAC in an SI:NMAC molar ratio of 1:

10.

15. Electrochemical system comprising at least one unipolar ionic conductivity eutectic polymer electrolyte SI PDEE according to any one of claims 1 to 8 and / or obtained according to the process according to any one of claims 9 to 12, said electrochemical system being more particularly a rechargeable battery, in particular a lithium-metal, lithium-ion, sodium-metal, sodium-ion, potassium-metal or potassium-ion battery, or comprising a single-ion eutectic electrolyte referred to as SI DEE according to any one of claims 13 or 14.

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