Solid polymer electrolyte materials comprising an anionic thermoplastic rubber matrix

Abstract

Solid polymer electrolyte materials comprising an anionic thermoplastic rubber matrix. The present invention relates to a solid polymer electrolyte material comprising an alkali metal salt and a thermoplastic rubber matrix, wherein the thermoplastic rubber matrix comprises a mixture of at least one crosslinked elastomer phase and at least one thermoplastic polymer phase, said crosslinked elastomer phase comprising elastomer polymer chains bearing one or more anionic groups. Figure for the abstract: None

Description

Title of the invention: Solid polymer electrolyte materials comprising an anionic thermoplastic rubber matrix

[0001] The present invention relates to the field of energy storage, and more particularly to solid-state batteries.

[0002] The present invention relates in particular to a solid polymer electrolyte material comprising an alkali metal salt and an anionic thermoplastic rubber matrix.

[0003] Lithium-ion (Li-ion) batteries offer exceptional energy density and are widely used, for example, in portable devices and electric and hybrid vehicles. They are based on the reversible exchange of lithium ions between positive and negative electrodes, separated by an ionically conductive liquid electrolyte. These liquid electrolytes are essential for ensuring good mobility of Li+ cations within the battery cell. However, they are based on organic solvents that are flammable, which can lead to potential thermal overheating in the event of an incident.

[0004] In this context, polymer electrolytes have been developed as ionically conductive solid electrolytes for solid-state batteries, notably to promote system safety and potentially increase stored energy. However, most of these batteries suffer from lithium dendrite growth during charge / discharge cycles, due to the use of a metallic lithium electrode, which can affect their morphological integrity and potentially lead to internal short circuits.

[0005] Dendrite growth is influenced by various parameters, including the quality of the interface between lithium and the solid electrolyte, since a poor interface can generate heterogeneity in the electric field at the interface and thus dendrite formation. In particular, Chazalviel et al. suggested that anion depletion near the Li electrode could lead to strong electric fields, which in turn cause dendrite growth (J.-N. Chazalviel, Phys. Rev. A 42 (1990) 7355). The other model proposed by Monroe and Newman suggests that lithium dendrite growth can be mechanically blocked if the shear modulus of the electrolytes is approximately twice that of lithium metal (C. Monroe, J. Newman, J. Electrochem. Soc. 152 (2005) 396-404).

[0006] In order to optimize solid-state batteries, ionically conductive solid electrolytes must therefore exhibit excellent ionic conductivity (to be able to operate in a power range comparable to that of Li-ion) as well as high mechanical properties (to promote battery cell integrity), while minimizing, or even eliminating, dendrite formation.

[0007] A recently published application by the inventors (WO 2023083801) describes solid polymer electrolytes comprising an alkali metal salt and a thermoplastic rubber matrix comprising a mixture of at least one crosslinked elastomer phase and at least one thermoplastic polymer phase. These solid polymer electrolytes exhibit improved properties compared to conventional polymer electrolytes, including better electrochemical stability than polyethylene oxide, high mechanical properties, and high resistance under pressure (including at room temperature and elevated temperature), making them particularly suitable for gelled systems. They also exhibit:

[0008] - good stability with high potential electrodes (e.g. LMFP);

[0009] - low flammability, (a non-flammable solvent such as TEP can be used) ;

[0010] - good high-temperature cyclability; and

[0011] - good cyclability at high cycling rates.

[0012] This document also mentions good resistance to dendritic growth of alkali metals, such as dendritic growth of lithium, but this aspect still needs improvement.

[0013] The aim of the invention is therefore to propose a solid polymer electrolyte material enabling the production of solid polymer electrolytes exhibiting excellent ionic conductivity combined with high mechanical properties, while minimizing, or even eliminating, the formation of dendrites.

[0014] The present invention therefore relates to a solid polymer electrolyte material comprising an alkali metal salt and a thermoplastic rubber matrix, in which the thermoplastic rubber matrix comprises a mixture of at least one crosslinked elastomer phase and at least one thermoplastic polymer phase, said crosslinked elastomer phase comprising elastomer polymer chains bearing one or more anionic groups.

[0015] Indeed, the inventors have discovered that the presence of anionic groups in the crosslinked elastomer phase makes it possible to preserve the excellent mechanical and electrochemical properties of the prior art solid polymer electrolytes comprising an alkali metal salt and a thermoplastic rubber matrix, while resolving the problem of dendrite formation. Without wishing to be bound by any theory, the inventors believe that the specific microstructure of the anionic thermoplastic rubber matrix, as detailed in the description below, makes it possible to stabilize the Li-metal interface and thus very effectively prevent dendrite formation.

[0016] A thermoplastic rubber matrix is ​​usually known by the acronym TPV, for ThermoPlastic Vulcanized.

[0017] Advantageously, the crosslinked elastomer phase is in the form of nodules dispersed in the thermoplastic polymer phase.

[0018] The crosslinked elastomer phase is therefore advantageously a phase dispersed homogeneously in the thermoplastic polymer phase.

[0019] Preferably, the cross-linked elastomer phase nodules are substantially spherical.

[0020] Preferably, the cross-linked elastomer phase nodules have a diameter less than or equal to 5 pm, preferably less than or equal to 2 pm, preferably less than or equal to 1 pm, preferably less than or equal to 0.5 pm, preferably between 10 nm and 5 pm.

[0021] The nodules are therefore relatively small, which is related to the preparation process, preferably by dry method, of the solid polymer electrolyte material. Such small sizes are advantageous in that they improve the properties of each phase of the thermoplastic rubber matrix. The smaller the nodules, the more the properties of each polymer are visible. In particular, the elastomeric properties of the crosslinked elastomer phase are very efficiently transferred (visible) to the anionic thermoplastic rubber matrix, which significantly improves the mechanical properties of the solid polymer electrolyte material, and therefore in particular of the solid polymer electrolyte comprising it (or being made of it).

[0022] Moreover, the smaller the size of the nodules and the greater the density of accessible anionic groups (on the surface of the nodules), which makes it possible to maximize their efficiency and / or decrease their content for a given efficiency.

[0023] Preferably, the anionic group(s) are grafted, preferably indirectly, to the elastomer polymer chains of the crosslinked elastomer phase.

[0024] Put another way, each anionic group is grafted, preferably indirectly, to an elastomeric polymer chain of the crosslinked elastomeric phase.

[0025] By "indirectly grafted" means that the atom of the anionic group(s) bearing the anionic charge is not directly bonded to an atom of the elastomeric polymer chains, but is separated from the atoms of the main chain of the elastomeric polymer by at least one atom.

[0026] According to one embodiment, the anionic group(s) are carried by one or more pendant groups that are grafted to the (main) chains of the elastomeric polymer. Put another way, each anionic group is carried by a pendant group that is grafted to a (main) chain of the elastomeric polymer.

[0027] This allows the anionic groups to be kept away from the (main) chains of the elastomer polymer, and advantageously allows the density of anionic groups to be maximized on the surface of the crosslinked elastomer phase nodules, and thus increases the effect related to their presence.

[0028] In summary, each of the above characteristics defining the particular microstructure of the thermoplastic rubber matrix (in particular the presence of anionic groups in the elastomer phase, the arrangement of the anionic groups, the presence of nodules, and the shape and size of the nodules) contributes to ensuring that the electric fields at the level of the electrolyte layer comprising the electrolyte material according to the invention are homogeneous and to avoiding the depletion of anions at the Li metal / electrolyte interface, which blocks the formation of dendrites.

[0029] Furthermore, the specific microstructure of the thermoplastic rubber matrix provides a uniform distribution of Li+ ions. In addition to the advantages mentioned above, this microstructure also acts as a Li+ ion redistributor, as reported by Chen-Zi Zhao et al. (Science Advances, 4 (2018), eaat3446) for composite polypropylene separators comprising LLZTO ceramic particles to prevent dendrite formation. In the present invention, the same Li+ ion distribution effect is observed, but using phase separation within the thermoplastic rubber matrix, with the crosslinked elastomer phase (dispersed as nodules) instead of the heavy and expensive LLZTO ceramic particles.

[0030] The term "alkali metal" refers to a chemical element such as lithium (Li), sodium (Na), and potassium (K). Lithium is a particular example of an alkali metal.

[0031] The alkali metal salt is preferably a lithium salt.

[0032] The alkali metal salt, preferably lithium salt, can be chosen from a variety of electrolyte salts (lithium salts) lithium ion conductors typically used for lithium batteries.

[0033] Various types of lithium salts used to conduct Li+ ions in electrolyte solutions for rechargeable lithium batteries are described in particular in Xu et al. Formulation of Blended-Lithium-Salt Electrolytes for Lithium Batteries Angew. Chem. Int. Ed. 2020, 59, 3400, and Auger et al. Materials Science and Engineering: R: Reports 2018, 134, 1-21.

[0034] Lithium hexafluorophosphate (LiPF6) is the principal lithium salt used in commercially available rechargeable lithium-ion batteries. Other examples of lithium salts suitable as alkali metal salts are lithium bis(trifluoromethanesulfonyl)imidate (LiTFSI), lithium bis(fluorosulfonyl)imidate (LiFSI), lithium hexafluoroarsenate (LiAsF6), lithium perchlorate (LiClO4), lithium hexafluorophosphate (LiPF6), te- lithium trafluoroborate (LiBF4), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(oxalato)borate (LiBOB) and lithium difluoro(oxalato)borate (LiBODFB).

[0035] The alkali metal salt can generally be present in dissociated form, either in one or more polymer phases, or in one or more optional additives possibly present in the solid polymer electrolyte material.

[0036] The alkali metal salt is preferably present in the thermoplastic polymer phase, preferably in dissociated form. This allows the thermoplastic polymer phase to acquire ionic conductivity properties. The alkali metal salt may nevertheless also be present, in smaller quantities, in the crosslinked elastomer phase.

[0037] Preferably, the anionic group(s) are chosen from among the carboxylate (-COO ), sulfonate (-SO3 ), sulfonylimidates, borates, phosphates, phosphonates and phosphinates groups.

[0038] Preferably, the sulfonylimidate groups have the following formula (I):

[0039] in which

[0040] - R1 is a halogen (preferably fluorine), a C1-C10 alkyl group or a aryl group, the alkyl and aryl groups being optionally substituted by one or more halogens, preferably by one or more fluorine atoms, preferably R1 is chosen from F, CF3, Ph and C6F5,

[0041] - X is an oxygen atom or an -NS(O)(O)-R' group, with R1 such that defined above, preferably is an oxygen atom, and

[0042] - R2 is -S(O)(O)- or -C(O)-, preferably is -S(O)(O)-.

[0043] Advantageously, the sulfonylimidate group has the following formula: OO d ô

[0044] Preferably, the borate groups are chosen from the oxalate borate group and the tetraphenyl borate groups, the phenyl groups optionally being substituted by one or more fluorine atoms, preferably the borate groups are chosen from an oxalate borate group of the following formula:

[0045]

[0046] a tetraphenyl borate group of the following formula: , preferably and a tetra(pentafluorophenyl) borate group with the following formula:

[0047] The phosphate groups have the following formula (II): O O™p—O. J | .A X' (H)

[0048] in which X' = OH, OR or O, R being chosen from a linear or branched Cl-CIO alkyl group, a linear or branched C2-C10 alkylene group, and a phenyl group.

[0049] The phosphonate groups have the following formula (III): O O—P— X' (W

[0050] in which X' = OH, OR or O , R being chosen from a linear or branched Cl-CIO alkyl group, a linear or branched C2-C10 alkylene group, and a phenyl group.

[0051] Advantageously, the anionic group(s) are COO groups.

[0052] Preferably, the COO groups are independently linked to the (main) elastomer polymer chains via a linear or branched Cl-Cl8 or C2-C18 alkyl group, preferably a linear or branched Cl-Cl8 alkyl group, preferably Cl-Cl2, more preferably C1-C7. The alkyl or alkylene groups may optionally be further substituted by an anionic group as defined above, preferably bearing at least a second COO group.

[0053] Put another way, the (main) elastomeric polymer chains therefore carry one or more, preferably several, grafts of formula -CH(Ra)(Rb), with, independently for each graft:

[0054] - either Ra = H and Rb is an alkyl group in C1-C18 or an alkylene group in C2-C18, linear or branched, preferably a linear or branched Cl-Cl alkyl group, preferably at C1-C12, more preferably at C1-C7, substituted by a COO group, preferably substituted at the end of the chain,

[0055] - either Ra = COO , and Rb is an alkyl group in C1-C18 or an alkylene group in C2-C18, linear or branched, preferably a linear or branched Cl-Cl alkyl group, preferably Cl-Cl 2, more preferably C1-C7, possibly substituted by a COO group, preferably at the end of the chain,

[0056] - either Ra and Rb are each independently an alkyl group in Cl-Cl8 or alkylene in C2-C18, linear or branched, preferably an alkyl group in Cl-Cl 8 linear or branched, preferably in Cl-Cl 2, more preferably in C1-C7, with the condition that at least one of Ra and Rb, preferably both Ra and Rb, is substituted by a COO group, preferably substituted at the end of the chain.

[0057] “Substituted at the end of the chain” means that preferably, Rb (and Ra if applicable) is of formula -Rb'-COO (and Ra is of formula -Ra'-COO, if applicable), with Rb' (and Ra', if applicable) being a linear or branched Cl-Cl8 or C2-C18 alkyl group, preferably a linear or branched Cl-Cl8 alkyl group, preferably Cl-Cl2, more preferably C1-C7.

[0058] Preferably, the counter-cation of the anionic group(s) is an alkali metal, preferably Li+.

[0059] The "elastomeric phase" refers to a homogeneous polymer phase in terms of chemical composition and / or texture, consisting of a polymer that exhibits elasticity similar to that of rubber, as defined by IUPAC.

[0060] This phase is said to be "crosslinked" or vulcanized because it has been subjected to a crosslinking reaction under the influence of one or more crosslinking agents. The elastomer is crosslinked in the sense that it comprises covalent bonds or relatively short sequences of chemical bonds to link two elastomeric polymer chains together, which were formed by the crosslinking reaction.

[0061] The appropriate crosslinking agents generally depend on the elastomeric polymer in question. These agents can be chosen from among organic peroxides, including dialkyl peroxides, such as Luperox® peroxides, like Luperox® DI marketed by Arkema.

[0062] Preferably, the elastomer is a crosslinkable polymer, typically selected from cis-1,4-polyisoprene (NR) and trans-1,4-polyisoprene, synthetic polyisoprene, polybutadiene, chloroprene rubber (CR), polychloroprene, neoprene, Baypren, butyl rubber (IIR), halogenated butyl rubbers such as chlorobutyl rubber (CIIR) and bromobutyl rubber (BIIR), styrene-butadiene rubber (SBR), styrene-butadiene-styrene polymers (SBS), styrene-ethylene-butadiene-styrene polymers (SEBS), nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), epichlorohydrin rubber (ECO), and polyacrylic rubber. (ACM, ABR), silicone rubber (SI, Q, VMQ), fluorosilicone rubber (FVMQ), fluoroelastomers (FKM for fluorocarbon-based fluoroelastomer materials defined by the international standard ASTM D1418,and FEPM), perfluoroelastomers (FFKM), polyether block amides, (PEBA), chlorosulfonated polyethylene (CSM), and ethylene-vinyl acetate (EVA).

[0063] Preferably, the elastomer is chosen from unsaturated or saturated rubbers, preferably the elastomer is a styrene-ethylene-butadiene-styrene polymer.

[0064] The term "thermoplastic polymer phase" means a polymer phase consisting of a plastic polymer which becomes flexible or malleable at a certain high temperature and which solidifies upon cooling.

[0065] Preferably, the thermoplastic polymer is chosen from polyacrylates, acrylonitrile butadiene styrene (ABS), nylon, polylactic acid (PLA), polybenzimidazole, polycarbonate, polyether sulfone, polyoxymethylene, polyether ether ketone, polyetherimide, polyethylene, polyphenylene oxide, poly(phenylene sulfide), polypropylene, polystyrene, poly(vinyl chloride), poly(vinylidene fluoride), polytetrafluoroethylene (Teflon), poly(ethylene oxide) (PEO) and polycaprolactone (PCL).

[0066] Preferably, the thermoplastic polymer is poly(ethylene oxide) (PEO) or polycaprolactone (PCL), advantageously is polycaprolactone (PCL).

[0067] Preferably, the thermoplastic polymer has a multinodal distribution of molecular masses, in particular has a bimodal or trimodal distribution of molecular masses, advantageously has a trimodal distribution of molecular masses.

[0068] A molecular weight distribution is said to be multimodal when it comprises several (at least two) groups of polymer chains with different average molecular weights. This characteristic is particularly noticeable in gel permeation chromatography (GPC), where the curves obtained for such polymers can exhibit several (at least two) maxima. A polymer containing two groups of molecules with different average molecular weights is said to be bimodal (a "bimodal" polymer). A polymer containing three groups of molecules with different average molecular weights is said to be trimodal (a "trimodal" polymer).

[0069] This advantageously allows for the plasticization and softening of the mixture during the preparation of the electrolyte material according to the invention, which enables, among other things, improved fluidity during processing as well as better adhesion and interfacing during calendering with other battery elements such as, for example, the Li-metal or other anodes and cathodes. Furthermore, during cycling, greater flexibility of the thermoplastic phase is achieved, thus facilitating the transport of Li+ as well as its coating and removal from the Li-metal.

[0070] Advantageously, the thermoplastic polymer phase is ionically conductive, preferably due to the presence of the alkali metal salt as defined above. The thermoplastic polymer phase therefore preferably comprises the alkali metal salt.

[0071] The solid polymer electrolyte material according to the invention may further comprise one or more additional ingredients, such as dopants and / or additives such as those usually used in solid polymer electrolytes.

[0072] According to one embodiment, the thermoplastic rubber matrix of the electrolyte material according to the invention may further comprise one or more dopants, generally to improve ionic conductivity. This dopant may be an organic molecule selected from trimethyl phosphate (TMP), triethyl phosphate (TEP), fluoroethylene carbonate (FEC), and vinylene carbonate (VC).

[0073] According to one embodiment, the thermoplastic rubber matrix of the electrolyte material according to the invention may also include one or more additives, such as solvents, plasticizers, lithium ceramic, inorganic fillers and radical scavengers.

[0074] The solvents can be chosen from organic liquids, water, ionic liquids. Examples include trimethyl phosphate (TMP), triethyl phosphate (TEP), fluoroethylene carbonate (FEC), and vinylene carbonate (VC).

[0075] The solvents can be selected from a variety of lithium-ion conductive liquids typically used for lithium batteries. Different types of solvents used for rechargeable lithium batteries are presented in Chem. Rev. 2004, 104, 4303-4417 and Chem. Rev. 2014, 114, 11503-1161.

[0076] Plasticizers can be chosen from the variety of plasticizers known in the melt processing industry, but they can also be any oligomer that reduces the viscosity of the overall formulation. Plasticizers can be compounds such as synthetic or natural oils or polymer oligomers such as glyme molecules, for example.

[0077] Lithium ceramic can be in the form of lithium-aluminium-titanium phosphate (LATP, Lii 3Al0.3Tii 7(PO4)3), lithium-lanthanum-zirconium oxide (LLZO, Li7La3Zr20i2).

[0078] Radical traps can be used to lengthen compounding times by controlling the rate of the crosslinking reaction. Radical traps include 2,2,6,6-tetramethylpiperidin-l-yl)oxidanyl (TEMPO); another example is presented by Bertin et al. Kinetic subtleties of nitroxide mediated polymerization. Chemical Society Reviews 2011, 40 (5), 2189-2198.

[0079] Inorganic fillers can be used to further strengthen polymer phases. They can be added to the elastomer phase along with the crosslinking agent (during step a) or a') of the processes described below) to ensure that they remain in that phase during crosslinking. Inorganic fillers include, for example, ceramic fillers such as TiO2 or SiO2.

[0080] According to one embodiment, in the thermoplastic rubber matrix of the electrolyte material according to the invention:

[0081] - the ratio between the volume of the cross-linked elastomer phase and the volume of the The thermoplastic rubber matrix is ​​between 40% and 60% (by volume); and / or

[0082] - the ratio between the thermoplastic polymer phase and the volume of the matrix thermoplastic rubber is between 40% and 60% (by volume).

[0083] Generally, the crosslinked elastomer phase and the thermoplastic polymer phase can be present in the thermoplastic rubber matrix in a volume ratio ranging from 40 / 60 to 60 / 40, advantageously around 50 / 50.

[0084] Their respective weight generally depends on their respective density.

[0085] According to one embodiment, the solid polymer electrolyte material may comprise, relative to the total weight of the solid polymer electrolyte material:

[0086] - 10 to 70% by weight of cross-linked elastomer phase;

[0087] - 10 to 70% by weight of thermoplastic polymer;

[0088] - 10 to 45% by weight of alkali metal salt;

[0089] - 0 to 70% by weight of doping agent; and

[0090] - 0 to 20% by weight of additives.

[0091] Another objective of the invention is to provide a solid-state battery that can be easily produced on an industrial scale.

[0092] The invention also relates, according to a first alternative, to a method for preparing a solid polymer electrolyte material according to the invention, comprising the following steps:

[0093] a) mixing an elastomeric polymer, a crosslinking agent, a compound bearing at least one anionic or anionizable group, and optionally a base capable of anionizing said anionizable group, at a temperature Tl, where Tl is between the melting temperature of the elastomeric polymer and the activation temperature of the crosslinking agent,

[0094] b) add an alkali metal salt and a thermoplastic polymer to the mixture obtained in step a), and

[0095] c) mix the mixture obtained in step b) at a temperature T2, where T2 is higher than the activation temperature of the crosslinking agent.

[0096] Preferably, the mixture obtained in step a) comprises a base capable of anionizing said anionizable group if it further comprises a compound bearing at least one anionizable group.

[0097] During step a), the elastomeric polymer, the crosslinking agent, the compound bearing at least one anionic or anionizable group, and the optional base capable of anionizing said anionizable group may be added simultaneously or sequentially. According to a preferred embodiment, the compound bearing at least an anionic or anionizable group, and the possible base capable of anionizing said anionizable group are first mixed with the elastomeric polymer, then the crosslinking agent is added, and mixed.

[0098] During step b), the alkali metal salt and the thermoplastic polymer can be introduced simultaneously or sequentially into the mixture obtained in step a). According to a preferred embodiment, the thermoplastic polymer is added to the mixture obtained in step a) first, and then the alkali metal salt is added and mixed.

[0099] Step b) can be carried out at the temperature Tl of step a) or at a different temperature, preferably higher than temperature Tl, provided that it is lower than the activation temperature of the crosslinking agent. The temperature during step b) can be fixed or variable. Thus, according to this first alternative, the alkali metal salt is added before crosslinking.

[0100] According to a second alternative, the solid polymer electrolyte material according to the invention can be prepared according to a preparation process comprising the following steps:

[0101] a') mixing an elastomeric polymer, a crosslinking agent, a bearing compound at least one anionic or anionizable group, and possibly a base capable of anionizing said anionizable group, at a temperature Tl, where Tl is between the melting temperature of the elastomeric polymer and the activation temperature of the crosslinking agent,

[0102] b') add a thermoplastic polymer to the mixture obtained in step a'),

[0103] c') mix the mixture obtained in step b') at a temperature T2, where T2 is su above the activation temperature of the crosslinking agent, and

[0104] d') add an alkali metal salt to the mixture obtained in step c').

[0105] During step a'), the elastomeric polymer, the crosslinking agent, the compound bearing at least one anionic or anionizable group, and the optional base capable of anionizing said anionizable group may be added simultaneously or sequentially. According to a preferred embodiment, the compound bearing at least one anionic or anionizable group, and the optional base capable of anionizing said anionizable group, are first mixed with the elastomeric polymer, and then the crosslinking agent is added and mixed.

[0106] Step b') can be carried out at the temperature Tl of step a) or at a different temperature, preferably higher than temperature Tl, provided that it is lower than the activation temperature of the crosslinking agent. The temperature during step b') can be fixed or variable.

[0107] According to this second alternative, the alkali metal salt is added after initiation of the crosslinking of the elastomer polymer.

[0108] According to these first and second alternatives, step c) (and c'), respectively) allows the elastomeric polymer to be crosslinked, and the anionic group (possibly obtained by anionization of the anionizable group under the effect of the base) is grafted to the main chains of the elastomeric polymer during crosslinking (therefore during step c) or c')).

[0109] These first or second alternatives are preferred for preparing the solid polymer electrolyte material according to the invention, in particular by using a compound bearing at least one anionizable group and a base capable of anionizing said anionizable group during step a) (or a'), respectively).

[0110] According to a third alternative, the solid polymer electrolyte material according to the invention can be prepared according to a preparation process comprising the following steps:

[0111] a”) mixing an elastomeric polymer comprising at least one monomeric unit bearing an anionic or anionizable group, a crosslinking agent and possibly a base capable of anionizing said anionizable group, at a temperature Tl, where Tl is between the melting temperature of the elastomeric polymer and the activation temperature of the crosslinking agent,

[0112] b”) add a thermoplastic polymer, and optionally an alkali metal salt to the mixture obtained in step a”),

[0113] c”) mix the mixture obtained in step b”) at a temperature T2, where T2 is su above the activation temperature of the crosslinking agent, and

[0114] d”) if and only if an alkali metal salt has not been added during step b”), add an alkali metal salt to the mixture obtained in step c”).

[0115] The alkali metal salt is therefore added either during step b”) or during step d”).

[0116] Preferably, the mixture obtained in step a”) comprises a base capable of anionizing said anionizable group if the elastomeric polymer comprises one or more anionizable groups.

[0117] Alternatively, the base capable of anionizing said anionizable group is introduced during step b”) of the process according to the second alternative, if the elastomeric polymer comprises one or more anionizable groups. However, the alternative in which the base capable of anionizing said anionizable group is introduced during step a”) is preferred.

[0118] That the base capable of anionizing said anionizable group is introduced during step a”) or b”), it implies that the elastomeric polymer comprises one or more anionizable groups and that these anionizable groups are anionized during step(s) a”) and / or b”) and / or c”).

[0119] According to another possibility, the process according to the second alternative may include in addition, a step a(i) prior to step a) and comprising the supply of an elastomeric polymer comprising at least one monomeric unit bearing an anionizable group, and the anionization of said anionizable group, preferably by mixing the elastomeric polymer with a base capable of anionizing the anionizable group, to obtain an elastomeric polymer comprising at least one monomeric unit bearing an anionic group. In this case, preferably, neither step a) nor step b) comprises the addition of a base capable of anionizing the anionizable group, since the anionization has been carried out during step a(i).

[0120] According to one embodiment, the process according to the second alternative may further include a step aO”) prior to step a”) and possibly prior to step al”) if present, comprising the supply of an elastomeric polymer and the grafting of an anionic or anionizable group onto said elastomeric polymer, preferably onto the (main) chains of the elastomeric polymer.

[0121] According to another embodiment, the process according to the second alternative may further include a step aO'”) prior to step a”) and possibly prior to step al”) if present, comprising the supply of an elastomeric polymer by polymerization of at least one monomer bearing an anionic or anionizable group.

[0122] For the processes according to the first, second, and third alternative:

[0123] - the elastomeric and thermoplastic polymers are as defined above for the solid polymer electrolyte material;

[0124] - the alkali metal salt is as defined above for the electrolyte material solid polymer;

[0125] - the anionic groups are as defined above for the material solid polymer electrolyte;

[0126] - by anionizable group, we mean a group of atoms capable of to become anionic, by losing at least one of its constituent atoms, preferably a hydrogen atom, for example under the action of a base. Anionizable groups include, for example:

[0127] - the COOH group,

[0128] - the SO3H group,

[0129] - sulfonimide groups of formula (!') with R1, R2 and X as defined above for formula (I), 5 "R (r $

[0130] - the phosphoric acid derived groups of formula (II'), 0 with R' being chosen from H, an alkyl group in Cl-ClO, HQ—P ? i A GOLD ! OH linear or branched, a C2-C10 alkylene group, linear or branched, and a phenyl group, and

[0131] - phosphonic acid derived groups of formula (III'): q with R' being chosen from H, an alkyl group in Cl-ClO, i ï > ï wwww*. । «wr ww^v ÿ .ww* I ' GOLD' linear or branched, a C2-C10 alkylene group, linear or branched, and a phenyl group.

[0132] Advantageously, the anionizable group is COOH.

[0133] Preferably, the compound bearing at least one anionic or anionizable group is a compound bearing at least one COO or COOH group. Preferably, it is a compound bearing at least one COOH group, in particular a compound of formula Rc-COOH or of formula Rc-COO, Rc being a linear or branched C1-C36 alkyl or C2-C36 alkylene group.

[0134] Preferably, Rc comprises at least one unsaturation. The presence of this unsaturation facilitates the grafting of the compound onto the main chains of the elastomer polymer.

[0135] Preferably, Rc is in C2-C24, preferably in C4-C18, more preferably in C4-C12.

[0136] Rc can further be substituted by an anionic group as defined above, preferably bearing at least a second COOH or COO group, preferably at the end of the chain.

[0137] Advantageously, the compound bearing at least one anionic or anionizable group has the formula A-Rc'-A, with A being independently COOH or COO-, preferably COOH, and Rc' is a linear or branched alkyl group in the C1-C36 or alkylene group in the C2-C36 range. Preferably, Rc' comprises at least one unsaturation. Preferably, Rc' being in the C2-C24 range, more preferably in the C4-C18 range. tiellement en C4-C12. An example of a compound bearing at least one anionic or anionizable group is sebacic acid or the corresponding lithium sebacate dianion, or adipic acid or the corresponding lithium adipate dianion.

[0138] Preferably, for each process, the possible base capable of anionizing the anionizable group is added in a molar quantity substantially equivalent (stoichiometric with respect to) to the molar quantity of anionizable group(s).

[0139] By "anionize" we mean removing an atom, for example a hydrogen, from a group of atoms so that this group of atoms becomes anionic.

[0140] The base capable of anionizing the anionizable group is preferably a lithium salt, organic or inorganic. It may be an organolithium compound, such as MeLi or nBuLi, a lithium alkanolate, particularly a C1-C2 one, or LiOH. LiOH is particularly preferred because the by-product of the anionization reaction is water.

[0141] The melting temperature of the elastomer polymer is defined as the temperature of its melting point, at which the polymer passes from the solid form to the molten form.

[0142] The crosslinking agent is as defined above. Its activation temperature is defined as the temperature that triggers the crosslinking reaction.

[0143] T1 and T2 depend on the nature of the elastomer polymer and the crosslinking agent.

[0144] Additional optional ingredients as defined above may be added during step a) or a') or a”) and / or step b) or b') or b”), as appropriate.

[0145] As a general rule, dopants can be added in step a) or b), or a') or b') or a") or b").

[0146] Generally, additives can be added in step a) or b), or a') or b'), or a") or b").

[0147] The processes of the invention can be implemented by extrusion.

[0148] Generally, the mixing steps a) and b), or a') and b'), or a") or b"), can be carried out in one or more heated extruders or in one or more internal mixers.

[0149] Steps c) and c'), d') and optional step d”) can also be carried out in one or more heated extruders or in one or more internal mixers.

[0150] Suitable extruders may be of the twin-screw type.

[0151] Preferably, the solid polymer electrolyte material is therefore obtained at the end of step c), d'), and c") or d") in the form of extrudates or filaments.

[0152] After step c), d'), and c") or d"), the resulting solid polymer electrolyte material can be shaped according to a step e) to give it the desired shape, in particular to give it the shape of a solid polymer electrolyte, typically a film. Step e) of shaping is typically carried out by extrusion calendering.

[0153] Alternatively, step e) may include the additive printing of a solid polymer electrolyte layer using the solid polymer electrolyte material of the invention as a raw material.

[0154] Another object of the present invention therefore relates to a solid polymer electrolyte comprising a solid polymer electrolyte material according to the invention. As mentioned above, this solid polymer electrolyte is preferably in the form of a film. It can also be in the form of a three-dimensional layer obtained by additive printing.

[0155] The present invention relates more broadly to an electrochemical element, preferably of an all-solid battery, comprising a solid polymer electrolyte material according to the invention.

[0156] In this document, the term "all-solid battery element" means an element comprising a positive electrode / electrolyte / negative electrode assembly configured to store the electrical energy produced by a chemical reaction and release it in the form of an electric current.

[0157] The present invention therefore also relates to an electrochemical element, preferably of an all-solid battery, comprising a solid polymer electrolyte as defined above, the electrochemical element further comprising a positive electrode and a negative electrode.

[0158] Typically, the battery element of the invention is a Li-ion cell.

[0159] The positive electrode comprises a current collector, at least one face of which is coated with a layer of a composition of positive active materials. "Composition of active materials" means a composition comprising one or more active materials and optionally one or more binders and one or more electronically conductive materials.

[0160] The positive current collector is a solid or perforated metal strip which may be made of aluminum or an aluminum alloy or steel or stainless steel. Its thickness may be in the range of 6 to 30 µm or 5 to 20 µm or 10 to 15 µm, preferably 10 to 15 µm.

[0161] The positive active material can be any positive active material known in lithium element technology. It can be a lithium oxide of at least one transition metal, an LVPF-type active material, or a lithium phosphate of at least one transition metal.

[0162] The lithium oxide of at least one transition metal may be selected from:

[0163] i) a lithium oxide of nickel, manganese and cobalt of formula Liw(NixMnyCozMt)O2(NMC) where 0.9 <w<l,l ; 0<x 0<y 0<z 0<t m étant choisi dans le groupe constitué de al, b, mg, si, ca, ti, v, cr, fe, cu, zn, y, zr, nb, w, Mo, S, Sr, Ce, Ta, Ga, Nd, Pr, La and mixtures thereof;

[0164] ii) a lithium oxide of nickel, cobalt and aluminium of formula Liw(NixCoyAlzMt)O2(NCA) where 0.9 <w<l,l ; 0<x 0<y 0<z 0<t m étant choisi dans le groupe constitué de al, b, mg, si, ca, ti, v, cr, mn, fe, cu, zn, y, zr, nb, w, mo, s, sr, ce, ta, ga, nd, pr, la et des mélanges ceux-ci iii) a compound of formula Lii+xMbxO2_yFy with cubic crystal structure where 0 <x<0,5 et 0<y<l m représente un élément choisi dans le groupe constitué de na, k, mg, ca, b, sc, ti, v, cr, mn, fe, co, ni, cu, zn, al, y, zr, nb, mo, ru, ag, sn, sb, ta, w, bi, la, pr, eu, nd sm des mélanges ceux-ci ;

[0165] iv) a lithium nickel manganese oxide (NMX) of formula Lia(Nii_x_y_zMnxCoyMz)O2 with 0.9 <a<l,l ; 0,60<l-x-y-z<0,80 0<x 0<y<0,02 0 <z ; et m étant choisi dans le groupe consistant en al, b, mg, si, ca, ti, v, cr, fe, cu, zn, y, zr, nb, w, mo, s, sr, ce, ga, ta, nd, pr, la des mélanges de ceux-ci

[0166] v) a lithium nickel and manganese oxide of formula Liw(NixMnyCozMt)O2 where 1.1 <w<1,6 ; 0<x 0,50<y<0,80 0<z<0,02 0<t m étant choisi dans le groupe constitué de al, b, mg, si, ca, ti, v, cr, fe, cu, zn, y, zr, nb, w, mo, s, sr, ce, ta, ga, nd, pr, la et des mélanges ceux-ci.

[0167] vi) a lithium nickel manganese oxide of formula LixMn2_y zM'yM"zO4 ô where M' and M" are chosen from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo; M' and M" being different from each other, and 1 <x<1,4 ; 0<y<0,6 0<z<0,2 0<ô<l,

[0168] and mixtures of different compounds of categories i) to vi).

[0169] LVPF-type active materials conform to the formula Lii+xVi yMyPO4Fz with 0 <x<0,15, 0<y<0,5, 0.8<z<l,2, et m est choisi parmi le groupe consistant en ti, al, mg, mn, fe, co, y, cr, cu, ni zr.

[0170] The lithium phosphate of at least one transition metal may be selected from: a) a lithium iron phosphate of formula LixFei yMyPO4 (LFP), where 0.8 <x<l,2 ; 0<y<0,6 et m est choisi dans le groupe consistant en al, b, mg, k, si, ca, ti, v, cr, co, cu, mn, ni, zn, y, zr, nb, w, pb, mo, s des mélanges de ceux-ci

[0171] b) a lithium manganese phosphate of formula LixMni yMyPO4 (LMP), where 0.8 <x<l,2 ; 0<y<0,6 et m est choisi dans le groupe consistant en al, b, mg, k, si, ca, ti, v, cr, co, cu, fe, ni, zn, y, zr, nb, w, pb, mo, s des mélanges de ceux-ci

[0172] c) a lithium manganese and iron phosphate of formula: LixMni y zFeyMzPO4 (LMFP) where 0.8 <x<l,2 ; 0,5<l-y-z<l; 0<y+z<0,5 0<y<0,50 et 0<z<0,2 m est choisi dans le groupe constitué de al, b, mg, k, si, ca, ti, v, cr, co, cu, ni, zn, y, zr, nb, w, pb, mo, s des mélanges ceux-ci

[0173] d) and mixtures of different compounds of categories a) to c).

[0174] The term "positive electrode" refers to the electrode operating as the cathode when The battery is discharging, and the electrode is functioning as the anode when the battery is charging.

[0175] The negative electrode comprises a current collector, at least one face of which is coated with a layer of a negative active material composition. The current collector is prepared in a conventional manner. The negative electrode active material is not particularly limited. It may be selected from the following groups and mixtures thereof:

[0176] - Metallic lithium or a metallic lithium alloy

[0177] - Graphite

[0178] - Silicon

[0179] - Anode-free type

[0180] - a titanium niobium oxide of the TNO type

[0181] - a lithia-bound titanium oxide or a titanium oxide capable of being lithia-bound, of the LTO type.

[0182] Examples of lithia-formed titanium oxides are spinel LqTisOn, Li2TiO3, ram-sdellite Li2Ti3O7, LiTi2O4, LixTi2O4, with 0 <x<2 et li2na2ti60i4.

[0183] A preferred LTO compound has the formula Lq aMaTi5 bM'bO4, for example Li4Ti50i2 which can also be written Li4 / 3Ti5 / 3O4.

[0184] The term "negative electrode" refers to the electrode operating as the anode when the battery is discharging, and the electrode operating as the cathode when the battery is charging.

[0185] According to another object, the present invention also relates to an electrochemical module comprising the stacking of at least two electrochemical elements according to the invention, each element being electrically connected to one or more other element(s).

[0186] The term "module" therefore designates the set of several electrochemical elements, this set being able to be in series and / or in parallel.

[0187] According to another object, the invention also relates to a battery or "accumulator" comprising one or more modules according to the invention. The term "battery" therefore designates the assembly of one or more modules according to the invention.

[0188] Example of a process for preparing electrolyte materials according to the invention

[0189] The electrolyte material according to the invention can be prepared according to the protocol following :

[0190] Step a /

[0191] The elastomeric polymer (e.g., hydrogenated nitrile rubber HNBR), a compound bearing at least one anionizable group (e.g., adipic acid or sebacic acid), a base capable of anionizing these anionizable groups (such as LiOH), and an elastomeric crosslinking agent (e.g., the compound sold under the name Luperox® Di) are mixed. The amount of The base used is essentially stoichiometric with respect to the amount of anionizable groups: for example, for 0.53 g of adipic acid, 0.174 g of LiOH is used. The amount of crosslinking agent is adjusted according to the knowledge of a person skilled in the art. The amount of compound bearing at least one anionizable group can be, for example, 5% by mass relative to the mass of the elastomeric polymer.

[0192] These ingredients can be mixed in an extruder or mixer, for example, an Xplore® brand extruder or mixer. Mixing is carried out at a temperature Tl between the melting temperature of the elastomer and the activation temperature of the crosslinking agent (for example, 80 °C with HNBR and Luperox® Di). Preferably, these ingredients are mixed sequentially, first mixing the elastomer, the base, and the compound bearing the anionizable groups until a homogeneous mixture is obtained, and then adding the crosslinking agent.

[0193] Step b /

[0194] A thermoplastic polymer (for example, a polycaprolactone with a molecular mass of approximately 80,000 g / mol) is added to the mixture obtained in step a. This addition can be carried out by heating, to facilitate mixing, but always at a temperature below the activation temperature of the crosslinking agent (for example, up to 120 °C). The mass of the thermoplastic polymer can, for example, be substantially equivalent to the mass of the mixture obtained in step a.

[0195] Step c /

[0196] The mixture obtained in step b is heated to a temperature T2 higher than the activation temperature of the crosslinking agent (for example 170 °C), while being continuously stirred. The elastomeric polymer crosslinks.

[0197] Step d /

[0198] After crosslinking the elastomeric polymer, an alkali metal salt (e.g., LiTFSI) is added to the mixture obtained in step c, still at temperature T2. Mixing continues until homogenized. The amount of alkali metal salt is approximately 30% by mass of the mass of the mixture obtained in step c.

[0199] The electrolyte material obtained typically comprises about 35% by mass of elastomer phase, about 40% by mass of thermoplastic polymer and about 25% by mass of alkali metal salt. < / z> < / a<l,l>

Claims

Demands

1. Solid polymer electrolyte material comprising an alkali metal salt and a thermoplastic rubber matrix, wherein the thermoplastic rubber matrix comprises a mixture of at least one crosslinked elastomer phase and at least one thermoplastic polymer phase, said crosslinked elastomer phase comprising elastomer polymer chains bearing one or more anionic groups.

2. Solid polymer electrolyte material according to claim 1, wherein the crosslinked elastomer phase is in the form of nodules dispersed in the thermoplastic polymer phase.

3. Solid polymer electrolyte material according to claim 2, wherein the crosslinked elastomer phase nodules have a diameter less than or equal to 5 pm, preferably less than or equal to 2 pm, preferably less than or equal to 1 pm, preferably less than or equal to 0.5 pm, preferably between 10 nm and 5 pm.

4. Solid polymer electrolyte material according to any one of the preceding claims, wherein the anionic group(s) are grafted, preferably indirectly, to the elastomer polymer chains of the crosslinked elastomer phase.

5. Solid polymer electrolyte material according to any one of the preceding claims, wherein the anionic group(s) are selected from the carboxylate, sulfonate, sulfony-limidate, borate, phosphate, phosphonate and phosphinate groups.

6. Solid polymer electrolyte material according to any one of the preceding claims, wherein the alkali metal salt is a lithium salt.

7. Solid polymer electrolyte material according to any one of the preceding claims, wherein the elastomer is selected from unsaturated or saturated rubbers, preferably the elastomer is a styrene-ethylene-butadiene-styrene polymer.

8. Solid polymer electrolyte material according to any one of the preceding claims, wherein the thermoplastic polymer is polycaprolactone.

9. A solid polymer electrolyte material according to any one of the preceding claims, wherein the thermoplastic polymer exhibits a multimodal molecular weight distribution, in par- ticulier exhibits a trimodal distribution of molecular masses.

10. Solid polymer electrolyte material according to any one of the preceding claims, wherein the thermoplastic rubber matrix further comprises a dopant, preferably selected from trimethylphosphate, triethylphosphate, fluoroethylene carbonate and vinylene carbonate.

11. Solid polymer electrolyte material according to any one of the preceding claims, comprising: - 10 to 70% by weight of crosslinked elastomer phase; - 10 to 70% by weight of thermoplastic polymer; - 10 to 45% by weight of alkali metal salt; - 0 to 70% by weight of dopant; and - 0 to 20% by weight of additives.

12. A method for preparing a solid polymer electrolyte material according to any one of the preceding claims, comprising the following steps: a) mixing an elastomeric polymer, a crosslinking agent, a compound bearing at least one anionic or anionizable group, and optionally a base capable of anionizing said anionizable group, at a temperature T1, where T1 is between the melting temperature of the elastomeric polymer and the activation temperature of the crosslinking agent, b) adding an alkali metal salt and a thermoplastic polymer to the mixture obtained in step a), and c) mixing the mixture obtained in step b) at a temperature T2, where T2 is greater than the activation temperature of the crosslinking agent.

13. A method for preparing a solid polymer electrolyte material according to any one of claims 1 to 11, comprising the following steps: a') mixing an elastomeric polymer, a crosslinking agent, a compound bearing at least one anionic or anionizable group, and optionally a base capable of anionizing said anionizable group, at a temperature T1, where T1 is between the melting temperature of the elastomeric polymer and the activation temperature of the crosslinking agent, b') adding a thermoplastic polymer to the mixture obtained in step a'), c') mixing the mixture obtained in step b') at a temperature T2, where T2 is greater than the activation temperature of the crosslinking agent, and d) add an alkali metal salt to the mixture obtained in step c').

14. Solid polymer electrolyte comprising a solid polymer electrolyte material according to any one of claims 1 to 11.

15. Electrochemical element comprising an electrolyte according to claim 14, further comprising a positive electrode and a negative electrode.

16. Battery comprising one or more modules, each module comprising the stacking of at least two electrochemical elements according to claim 15.