HYBRID SOLID ELECTROLYTE WITH REDUCED POLYMER / CERAMIC INTERFACIAL RESISTANCE

Abstract

HYBRID SOLID ELECTROLYTE WITH REDUCED POLYMER / CERAMIC INTERFACIAL RESISTANCE The present application relates to ceramic / polymer hybrid solid electrolytes with improved interfacial resistance, comprising a surface-dehydrated pre-treated ceramic. Figure for abstract: None

Description

Title of the invention: HYBRID SOLID ELECTROLYTE WITH REDUCED POLYMER / CERAMIC INTERFACIAL RESISTANCE

[0001] The present invention relates to the field of batteries, and in particular all-solid-state hybrid electrolyte batteries.

[0002] Unlike flammable liquid organic electrolytes, solid electrolytes represent promising candidates for the development of safer lithium metal and Li-ion batteries.

[0003] Solid electrolytes can be of solid polymer or ceramic type: Polymer type electrolytes allow good contacts with the active material particles and can be shaped by economical and automated solvent-free processes such as extrusion, but have low ionic conductivities. Ceramic type electrolytes benefit from high ionic conductivity, but are limited by their poor ability to maintain intimate contacts with the electrode materials.

[0004] Hybrid (or composite) solid electrolytes combining ceramic and polymer electrolytes have been described in particular by Keller et al, J. Power Sources, 2018, 392, 206-225. They represent a preferred development path. However, these electrolytes require an organic / inorganic interface, the resistance of which must be minimized to optimize electrochemical performance.

[0005] Chen et al ACS Energy Letters 2019, 4, 1080-1085 reports the contrasting effects of plasticizing polymers, such as TEGDME and DMC, on the interfacial resistance between polyethylene glycol (PEO, polyethylene oxide) and a LiCGC ceramic.

[0006] It therefore remains to improve the interfacial resistance of hybrid solid electrolytes in order to accelerate the progress of all-solid technologies to envisage their industrialization with limited risks in terms of safety, while maintaining satisfactory conductivity and energy densities.

[0007] It has now been discovered that the interfacial resistance can be reduced by appropriate treatment of the ceramic.

[0008] According to a first object, the present invention aims at a hybrid solid electrolyte comprising

[0009] a pre-treated oxide type ceramic and

[0010] an ionic conductive polymer,

[0011] characterized in that the pre-treated ceramic is dehydrated on the surface.

[0012] The invention therefore relates to a hybrid solid electrolyte, i.e. a solid polymer electrolyte (SPE) based on ceramic and polymer, the ceramic of which has undergone a desiccant pre-treatment before assembly with the polymer.

[0013] According to the invention, the ceramic is of the oxide type. It can be chosen from lithium ion-conducting ceramics, and can in particular be chosen from ceramics of the Nasicon, Lisicon, Garnet, Perovskite families.

[0014] We can more particularly cite LATP, LAGP, LLTO, LLZO ceramics.

[0015] These ceramics and their use in solid electrolytes are known from the literature.

[0016] Thus, LATP denotes ceramics comprising Li, Al, Ti, P, and possibly other substitution elements such as Ge, Zr. Representative LATPs may have the formula Lii+xAlxTi2x(PO4)3 (where 0 <x<l) et sont par exemple décrites par Thokchom, et al dans J. Power Sources, vol. 195, p. 870, 2010.

[0017] According to one embodiment, the LATP ceramic may be an Ohara LiCGC (Li2O-A1203-SiO2-P2O5-TiO2-GeO2) type ceramic. It is notably commercially available (Ohara corporation).

[0018] LAGP denotes ceramics based on Li, Al, Ge and P, corresponding in particular to the formula Li1+xAlxGe2 x(PO4)3 (where 0 <x<l)

[0019] LLZO denotes ceramics based on Li, La and O, such as that of formula Li7La3Zr20i2 described by Murugan et al in Angew. Chem. Int. Ed., 46 (2007), p. 7778.

[0020] LLTO refers to ceramics comprising Li, La, Ti and O, such as La0.57Lio.29Ti03 marketed by Toho Titanium Co Ltd.

[0021] According to the invention, the ceramic is at least partially dehydrated on the surface, this partial dehydration being understood in relation to the native ceramic.

[0022] The term “native ceramic” refers to ceramic before pre-treatment, and refers in particular to commercially available ceramics, or to rehydrated ceramics, for example ceramics which may have undergone a desiccant treatment but subsequently stored in conditions conducive to rehydration.

[0023] In these native ceramics, a portion of the surface oxygen atoms is hydrated. Thus, these surface oxygen atoms typically present in the form (MO), where M refers to a cation of the solid electrolyte, are at least partly in the form of hydroxyl functions (OH).

[0024] Said cation M is a cation which constitutes in the structure of the inorganic solid electrolyte, the cationic network in interaction with the anionic framework constituted of oxygens ("O2", bulk oxygen), These are generally metal cations (Al, Sn, etc.), transition metals (Ti, Zr, Ta, etc.), alkali or alkaline earth, metaloid (Si, Ge) or non-metals (P).

[0025] OM bonds refer to the iono-covalent bonds between oxygen and these cations at the heart of the structure (crystalline or glassy) of the solid, as opposed to the OH bonds that surface oxygens can form in equilibrium with their environment. These surface OH bonds represent a defect in the structure and give a signature that can be analyzed in the XPS response.

[0026] Thus, these native ceramics can be defined by the atomic percentage of oxygen present in the surface hydroxyl functions %O(OH); and by the atomic percentage of oxygen present in the surface oxide functions %O(MO)i, where M refers to the metal cation and i refers to the initial value of the native ceramic, i.e. before treatment.

[0027] Said atomic percentages of oxygen can in particular be measured by XPS (X-ray induced photoelectron spectrometry).

[0028] For these native ceramics, the %0(0H); / %0(M-0)i ratio is typically greater than 20%.

[0029] The pre-treatment is said to be desiccant in that its function is to reduce the quantity of hydroxyl functions (OH), that is to say to reduce the proportion of hydroxyl functions in favor of oxide functions.

[0030] Thus, according to one embodiment, the pre-treated ceramics have a %O(OH)f / %O(MO)f ratio, where f refers to the pre-treated ceramic, is typically less than 20%, in particular less than 15%.

[0031] According to one embodiment, the ceramic can be pre-treated by a heat treatment, in particular at a temperature between 100 and 700°C, preferably between 200 and 400°C.

[0032] According to an alternative, or cumulative, embodiment, the ceramic can be pre-treated by the action of a hydrophilic and polar solvent. Said solvent can also be aprotic.

[0033] Typically, said solvent may be chosen from acetonitrile (ACN), dimethylformamide (DMF), dimethyl carbonate (DMC), methanol, isopropanol, dimethyl sulfoxide (DMSO), cyclohexane and sulfolane.

[0034] Ionic polymer refers to polymers conventionally used in solid polymer batteries. Typically the ionic polymer is selected from ether, carbonate, nitrile, acetate, imine, or lactone-based (co)polymers, etc.

[0035] Thus, we can notably cite polyethylene oxide (PEO) or polycaprolactone (PCL), notably PEO.

[0036] According to one embodiment, the hybrid solid electrolyte may also comprise one or more additional ingredients, typically present in hybrid solid electrolytes.

[0037] It is thus possible to cite the additional presence of metal salt, in particular a lithium salt, such as LiTFSI (Lithium bis(trifluoromethanesulfonyl)imide), LiFSI (Lithium bis(fluorosulfonyl)imide), LiNO3 (lithium nitrate), LiBOB (Lithium bis(oxalato)borate), LiDFOB (lithium difluoro(oxalato)borate), LiPF6 (lithium hexafluorophosphate), LiBF4 (lithium tetrafluoroborate), LiCF3SO3 (lithium triflate, LiTf), LiC104 (lithium perchlorate) or a mixture of salts.

[0038] When the ionic polymer has been prepared by solvent means, it may possibly include traces of residual solvent from its preparation process.

[0039] Thus, according to one embodiment, the hybrid solid electrolyte according to the invention may comprise traces of residual solvent as an additional ingredient.

[0040] According to another object, the present invention also relates to the process for preparing a hybrid solid electrolyte according to the invention, said process comprising the steps of: - Desiccant pre-treatment of an oxide-type ceramic having an atomic percentage of oxygen in the hydroxyl functions %O(OH);, so as to obtain a pre-treated ceramic having an atomic percentage of oxygen present in the surface hydroxyl functions %O(OH)f, said percentages being measured by XPS, and such that the ratio %O(OH)f / %O(OH)i is between 20 and 60%, and - Contacting the pre-treated ceramic with an ionic conductive polymer.

[0041] According to one embodiment, the desiccant treatment may comprise the heat treatment of the ceramic at a temperature between 100 and 700°C, preferably between 200 and 400°C.

[0042] According to an alternative or cumulative embodiment, the desiccant pre-treatment may comprise bringing the ceramic into contact with a hydrophilic and polar solvent. This may in particular be carried out by spraying the solvent onto the ceramic or immersing (or dipping) the ceramic in the solvent.

[0043] According to either of the alternatives, the process may further comprise the prior step of preparing the polymer by dry and / or solvent route. It is therefore understood that the ionic polymer may optionally comprise traces of residual solvent from its preparation process.

[0044] By contacting is meant the assembly of the electrolyte by means of the pre-treated ceramic and the conductive polymer. According to one embodiment, this step of contact can be achieved by simply mixing these two constituents, or by a sandwich-type assembly (two outer layers of polymers including an inner layer of ceramic), or even according to a system with deposited polymer / ceramic / polymer layers).

[0045] According to another object, the present invention also relates to a method for improving the interfacial resistance of a ceramic / polymer hybrid solid electrolyte such that the ceramic is of oxide type and such that the polymer is ionically conductive, said method comprising:

[0046] the preliminary desiccant treatment of said oxide-type ceramic having an atomic percentage of oxygen in the hydroxyl functions %O(OH);, so as to obtain a pre-treated ceramic having an atomic percentage of oxygen present in the surface hydroxyl functions %O(OH)f, said percentages being measured by XPS, and such that the ratio %O(OH)f / %O(OH)i is between 20 and 60%, and

[0047] the mixture of the ceramic thus pre-treated with the ionic conductive polymer.

[0048] According to another object, the present invention also relates to an electrochemical element comprising a hybrid solid electrolyte according to the invention.

[0049] The term "electrochemical element" means an elementary electrochemical cell consisting of the positive electrode / electrolyte / negative electrode assembly, operating as an accumulator, i.e. enabling the transformation of the energy supplied by a chemical reaction by restoring it in the form of current.

[0050] In solid-state elements, the electrolytic compounds may be included in the electrolytic layer, but may also be included partly within the electrodes.

[0051] A solid element according to the invention is therefore made up of a negative electrode layer, a positive electrode layer and an electrolytic separating layer, such that the electrolyte particles according to the invention are present within at least one of the three layers.

[0052] The electrochemical element according to the invention is particularly suitable for lithium accumulators, such as Li-ion, Li metal, primary Li (non-rechargeable) and Li-S accumulators. These materials can also be used in Na-ion, K-ion, or even Mg-ion or Ca-ion type accumulators.

[0053] The negative electrode layer typically consists of a conductive support used as a current collector on which is deposited the negative electrode material comprising a negative electrode active material to which the solid electrolyte and an electronically conductive material can be added. A binder can also be incorporated into the mixture.

[0054] The term "negative electrode" designates when the accumulator is discharging, the electrode functioning as an anode, the anode being defined as the electrode where an electrochemical oxidation reaction takes place (emission of electrons).

[0055] Within the scope of the present invention, the negative electrode may be of any known type.

[0056] It is understood that in systems without anode called “anode free”, a negative electrode is also present (generally initially limited to the current collector only).

[0057] The negative electrode active material is not particularly limited.

[0058] The positive electrode layer typically consists of a conductive support used as a current collector on which is deposited the positive electrode material comprising, in addition to the solid electrolyte, a positive electrode active material and a carbon electronic conductive material. A binder may also be incorporated into the mixture.

[0059] This carbon additive is distributed in the electrode so as to form an electronic percolating network between all of the particles of active material and the current collector.

[0060] The term “positive electrode” designates when the accumulator is discharging, the electrode functioning as a cathode.

[0061] Within the scope of the present invention, the positive electrode may be of any known type.

[0062] The electronically conductive material is generally chosen from graphite, carbon black, acetylene black, soot, graphene, carbon nanotubes or fibers or a mixture thereof.

[0063] A current collector is understood to mean an element such as a pad, plate, sheet or other, made of conductive material, connected to the positive or negative electrode, and ensuring the conduction of the flow of electrons between the electrode and the terminals of the battery. The current collector is preferably a two-dimensional conductive support such as a solid or perforated strip, made of metal, for example nickel, steel, stainless steel, or aluminum.

[0064] According to another object, the present invention also relates to an electrochemical module comprising the stack of at least two elements according to the invention, each element being electrically connected with one or more other element(s).

[0065] The term “module” therefore designates here the assembly of several electrochemical elements, said assemblies being able to be in series and / or parallel.

[0066] According to another of these objects, the invention also relates to a battery comprising one or more modules according to the invention.

[0067] The term “battery” means the assembly of one or more modules according to the invention. The invention preferably relates to accumulators whose capacity is greater than 100 mAh, typically 1 to 100 Ah. Figures

[0068] [Fig-1] [Fig.l] represents by squares the characteristic impedance spectrum recorded at 80°C for a reference PEO / LATP / PEO type system accompanied by the simulation (in solid line) by the software.

[0069] [Fig.2] [Fig.2] represents the comparison of the interfacial resistance of the LATP (LiCGC, Ohara) / polymer (PEO) ceramic hybrid electrolyte (normalized by the contact surface between the polymer and the ceramic), as a function of temperature, before and after pre-treatment with a desiccant polar solvent (acetonitrile (ACN), Dimethylformamide (DMF), DMSO, DMC, Isopropanol, Sulfolane):

[0070] the curve represented by the solid squares represents the interfacial resistance of the electrolyte constituted by the “native ceramic” (0.5M) / PEO;

[0071] the curve represented by the filled pentagons represents the interfacial resistance of an electrolyte constituted by the ceramic pre-treated in acetonitrile (ACN) (0.5M) / PEO;

[0072] the lower curve represented by the empty squares represents the interfacial resistance of an electrolyte constituted by the ceramic pre-treated in DMF (0.5M) / PEO;

[0073] the curve represented by the solid triangles whose point is oriented upwards represents the interfacial resistance of an electrolyte constituted by the ceramic pretreated in DMC (0.5M) / PEO;

[0074] the curve represented by the empty circles represents the interfacial resistance of an electrolyte constituted by the ceramic pre-treated in DMSO (0.5M) / PEO;

[0075] the curve represented by the solid circles represents the interfacial resistance of an electrolyte constituted by the ceramic pre-treated in Sulfolane (0.5M) / PEO;

[0076] the curve represented by the empty triangles whose point is oriented downwards represents the interfacial resistance of an electrolyte constituted by the ceramic pretreated in Isopropanol (0.5M) / PEO;

[0077] [Fig.3] [Fig.3] represents the interfacial resistance of the hybrid electrolyte LATP ceramic (LiCGC, Ohara) / polymer (PEO), as a function of storage time, when the ceramic was pre-treated with desiccant solvents. The legend is the same as that of [Fig.2].

[0078] [Fig.4] [Fig.4] represents the comparison of the interfacial resistance of the LLZO / polymer (PEO) ceramic hybrid electrolyte, as a function of temperature, before (squares) and after cyclohexane pretreatment (circles).

[0079] [Fig.5] [Fig.5] represents the comparison of the interfacial resistance of the LATP (LiCGC, Ohara) / polymer (PEO) ceramic hybrid electrolyte, as a function of temperature, before and after heat pre-treatment of the ceramic.

[0080] the curve represented by the solid squares represents the interfacial resistance of the electrolyte constituted by the “native ceramic” (0.5M) / PEO;

[0081] the curve represented by the empty hexagons represents the interfacial resistance of an electrolyte constituted by the ceramic pre-treated thermally for a duration of 12 hours (0.5M) / PEO;

[0082] the curve represented by the solid stars represents the interfacial resistance of an electrolyte constituted by the ceramic pre-treated thermally for a period of 72 hours (0.5M) / PEO;

[0083] [Fig.6] [Fig.6] represents the interfacial resistance of the LATP (LiCGC, Ohara) / polymer (PEO) ceramic hybrid electrolyte, as a function of storage time, when the ceramic was pre-treated either by a solvent or thermally. The legend is similar to Figures 2 and 3. Examples

[0084] In order to measure the interface resistance between the polymer (containing a lithium salt) and the ceramic, the polymer electrolyte was previously prepared in the following manner:

[0085] The preparation takes place in a glove box whose atmosphere is controlled in terms of water and dioxygen content (<1 ppm H2O and <5 ppm O2). The PEO polymer powder (100 kg / mol) is mixed with the lithium salt LiTFSI in a proportion corresponding to a salt concentration of 0.5M (mol.dm3) and the whole is heated to 80°C with regular stirring. Using a heating press, the mixture is hot pressed (70°C) in order to obtain a membrane from which polymer discs are cut.

[0086] On the other hand, the ceramic (LATP or LLZO) is pre-treated according to two methods:

[0087] i) it is either previously immersed in a polar solvent (here ACN, DMSO, DMC, sulfolane, isopropanol, DMF) for 1 min then the excess solvent is removed using an absorbent cloth, and left in the glove box overnight before being used for the measurement, ii) The second method consists of placing the ceramic in a sealed ampoule (Buchi) under secondary vacuum and heated to 200 °C for one to three days before transferring it to the glove box.

[0088] The cell for measuring the interface resistance between the polymer and the ceramic consists of a button cell composed of two stainless steel shims between which there is a polymer / ceramic / polymer sandwich. The latter is produced by hot pressing two discs of polymer membranes onto the two stainless steel shims. using a cover to delimit the contact surface of the polymer before placing a piece of ceramic between the two shims. The button cell is finally closed / sealed in a watertight manner and placed in a climatic chamber.

[0089] The measurement of the interfacial resistance is enabled by measuring the impedance of the battery in a frequency range of 7 MHz to 100 mHz using a potentiostat (VMP300 Biology) at different temperatures.

[0090] Finally, the analysis of the impedance spectrum of the cell reveals a resistive contribution in the medium frequency domain which corresponds to the desired quantity (i.e.) the interfacial resistance. The latter can be extracted using software (Zview) by injecting an equivalent electrical diagram taking into account all the contributions present in the impedance spectrum (inserted in [Fig.l]). The characteristic impedance spectrum recorded at 80°C for a reference PEO / LATP / PEO type system accompanied by the simulation (in solid line) by the software is represented in [Fig.l] represented by squares (experimental points).

[0091] Furthermore, the evolution of the interfacial resistance as a function of the temperature is often represented in an Arrhenius representation (1 / Rint vs 1000 / T) which gives access to the activation energy of the reaction (i.e.) the slope of the curve.

[0092] The following systems were studied:

[0093] NB: the term “pristine” used herein refers to commercial ceramic, used as is, without prior treatment. It is therefore used for reference purposes, and illustrates the ceramic referred to herein as “native”. • PEO / LATP system (LiCGC, Ohara): • PEO / LATP pristine interface (Reference) • PEO / LATP interface preprocessed in DMF • PEO / LATP interface preprocessed in ACN • PEO / LATP interface heat-pretreated (12h @ 200°C) • PEO / LATP interface pre-treated in DMSO • PEO / LATP interface preprocessed in DMC • PEO / LATP interface pretreated in Isopropanol • PEO / LATP interface pretreated in Sulfolane • PEO / LATP interface thermally pretreated +++ (72h @ 200°C) • PEO / LLZO system (Li7La3Zr2Oi2Sold by Toshima Mfg Co, Ltd): • PEO / LLZO pristine interface (Reference) • PEO / LLZO interface pretreated in cyclohexane • • XPS measurements: • LATP pristine (Reference) • LATP pretreated in DMF • LATP pre-processed in ACN

[0094] The initial values ​​(Interface resistance measured 1-2h after cell assembly) are illustrated in [Fig.2] in the case of LATP ceramic (LiCGC).

[0095] [Tables 1] Initial Value Interface @ 70°C 2 x Rint *A Gain w / w at ref Gain w / w at ref Q.cm2 Ratio % Ref: LATP pristine / PEO 191.6 1.0 0% LATP pretreated in DMF / PEO 154.6 1.2 -19% LATP pretreated in ACN / PEO 82.2 2.3 -57% LATP pretreated in DMSO / PEO 100.2 1.9 -48% LATP pretreated in DMC / PEO 81.8 2.3 -57% LATP pretreated in Sulfolane / PEO 131.3 1.5 -31% LATP pretreated in Isopropanol / PEO 126.5 1.5 -34%

[0096] Comments: The interface resistance is decreased when the ceramic is pretreated in a solvent. The greatest decrease is observed in the case of DMC and ACN solvent.

[0097] The final values ​​(Interface resistance measured several months after cell assembly) are illustrated in [Fig.2] and [Fig.3].

[0098] Over time, the interface resistances continue to decrease and seem to tend towards the same limit value of the order of [20-40 Q.cm2].

[0099] [Tables2] final value Interface @ 70°C 2 x Rint *A Gain w / w at r ref Gain w / w at r ref Q.cm2 Ratio % Ref: LATP pristine / PEO 154.8 1.0 0% LATP pretreated in DMF / PEO 44.4 3.5 -71% LATP pretreated in ACN / PEO 20.5 7.6 -87% LATP pretreated in DMSO / PEO 57.1 2.7 -63% LATP pretreated in DMC / PEO 22.4 6.9 -86% LATP pretreated in Sulfolane / PEO 92.3 1.7 -40% LATP pretreated in Isopropanol / PEO 68.2 2.3 -56% LLZO / PEO System

[0100] The initial values ​​(Interface resistance measured 1-2h after cell assembly) are illustrated in [Fig.4].

[0101] Comments: In the case of LLZO ceramic, the interface resistance decreases sharply in the case of cyclohexane. • Pretreatment of the ceramic at 200°C • LATP / PEO system #

[0102] The initial values ​​(Interface resistance measured 1-2h after cell assembly) are illustrated in [Fig.5].

[0103] [Tables3] Initial value Interface @ 70°C 2 x Ri nt *A Gain w / w at 1 a ref Gain w / w at 1 a ref Q.cm2 Ratio % Ref: LATP pristine / PEO 191.6 1.0 0% LATP pretreated in DMF / PEO 154.6 1.2 -19% LATP pretreated in ACN / PEO 82.2 2.3 -57% LATP pretreated in DMSO / PEO 100.2 1.9 -48% LATP pretreated in DMC / PEO 81.8 2.3 -57% LATP pretreated in Sulfolane / PEO 131.3 1.5 -31% LATP pretreated in Isopropanol / PEO 126.5 1.5 -34% LATP pretreated thermally 12h @ 200°C / PEO 94.2 2.0 -51% ATP heat-pretreated 72h @ 200°C / PEO 40.0 4.8 -79%

[0104] Comments: Heat treatment of ceramics is also an effective means of reducing interface resistance. It can be noted that when the duration of the pretreatment is extended, the reduction in resistance is greater.

[0105] The final values ​​(Interface resistance measured several months after cell assembly) are shown in [Fig.6].

[0106] [Tables4] Final Value Interface @ 70°C 2 x Rint *A Gain w / w at ref Gain w / w at ref Q.cm2 Ratio % Ref: LATP pristine / PEO 154.8 1.0 0% LATP pretreated in DMF / PEO 44.4 3.5 -71% LATP pretreated in ACN / PEO 20.5 7.6 -87% LATP pretreated in DMSO / PEO 57.1 2.7 -63% LATP pretreated in DMC / PEO 22.4 6.9 -86% LATP pretreated in Sulfolane / PEO 92.3 1.7 -40% LATP pretreated in Isopropanol / PEO 68.2 2.3 -56% LATP pretreated thermally 12h / PEO 17.3 9.0 -89% LATP thermally pretreated 72h / PEO 25.3 6.1 -84%

[0107] Over time, the interface resistances decrease (with different kinetics) and tend towards the same limit value of the order of [20-30 Q.cm2]. It can be noted that the heat treatment at 200°C for 72 hours makes it possible to be very close to this value from the start. General conclusions:

[0108] In the case of a PEO / LATP type system, pretreatment of the ceramic (solvent or thermal) is a means of significantly reducing the interface resistance.

[0109] For the PEO / LLZO system, the interface resistance also decreases when the ceramic is pretreated in cyclohexane.

[0110] In the present study, the reference system comprising a native ceramic exhibits higher interface resistance values ​​than any of those recorded in the case of pre-treated ceramics (by a solvent or thermally).

[0111] The lowest interface resistance was recorded in the case of a ceramic pre-treated heat for 72 hours for which the interface resistance was divided by a factor of 16 compared to the reference system. In the case of pre-treatment of the ceramic by solvent, the interface resistance was divided by a factor of 7 for ACN and DMC solvents.

[0112] Table 5 below shows the measurement of the chemical composition of the surface of the ceramic using the XPS technique, when the ceramic has been pretreated with a solvent and that of the “native” ceramic.

[0113] [Tables 5] Concentration atomigue U 0 (MO] 0 {GH? p Tt4+ T<3+ Ge Zr3d Ratio Q(Q$) / OjM-O) ÊOÊt^ {G. cm2: Rint(70X) ftnaîe value UŒC Native 9,2.. 41.7 93 6.1 13 24.6 23 03 43 1-1 0.23 1913 993 LiŒC Kg; treated, father!' ÂCN 8.2 443 49 63 13 26.4 2.4 ' 0.4 4.3 14. 0.10 32.2 28.2 UCGC pretreated by D WF 8.5 443 5.8 6.3 1<3.4 3.2 25.6 1S4.6 44.4

Claims

Claims

1. Hybrid solid electrolyte comprising a pre-treated oxide ceramic and an ionically conductive polymer, characterized in that the pre-treated ceramic is surface dehydrated, such that said pre-treated ceramic has a ratio of the atomic percentage of oxygen present in the surface hydroxyl functions relative to the atomic percentage of oxygen present in the surface oxide functions %O(OH)f / %O(MO)f of less than 20%, in particular less than 15%, said percentages being measured by XPS (X-ray induced photoelectron spectrometry), said ceramic before pre-treatment having a ratio of the atomic percentage of oxygen present in the surface hydroxyl functions relative to the atomic percentage of oxygen present in the surface oxide functions %O(OH); / %O(MO)i of greater than 20%.

2. A hybrid solid electrolyte according to claim 1 such that the ceramic is pre-treated by heat treatment.

3. Hybrid solid electrolyte according to any one of claims 1 to 2 such that the ceramic is pre-treated by the action of a hydrophilic and polar solvent.

4. A hybrid solid electrolyte according to claim 3 such that said solvent is selected from acetonitrile (ACN), dimethylformamide (DMF), dimethyl carbonate (DMC), methanol, isopropanol, dimethyl sulfoxide (DMSO), cyclohexane and sulfolane.

5. Hybrid solid electrolyte according to any one of the preceding claims such that the oxide type ceramic is chosen from ceramics of the Nasicon, Lisicon, Garnet, Perovskite families.

6. Hybrid solid electrolyte according to any one of the preceding claims such that the oxide ceramic is selected from Li2O-A1203-SiO2-P2O5-TiO2-GeO2 (LiCGC) ceramics, ceramics comprising Li, Al, Ti, P, and optionally other substitution elements such as Ge, Zr (LATP), ceramics based on Li, Al, Ge and P (LAGP), ceramics based on Li, La and 0 (LLZO), ceramics comprising Li, La, Ti and 0 (LLTO).

7. Hybrid solid electrolyte according to any one of the preceding claims such that the ionic polymer is chosen from polyethylene oxide (PEO), (co)polymers based on ether, carbonate, nitrile, acetate, imine, or lactone.

8. A hybrid solid electrolyte according to any preceding claim such that it further contains a metal salt.

9. A hybrid solid electrolyte according to claim 8 such that the metal salt is a lithium salt, such as LiTFSI (Lithium bis(trifluoromethanesulfonyl)imide), LiFSI (Lithium bis(fluorosulfonyl)imide), LiNO3 (lithium nitrate), LiBOB (Lithium bis(oxalato)borate), LiDFOB (lithium difluoro(oxalato)borate), LiPF6 (lithium hexafluorophosphate), LiBF4 (lithium tetrafluoroborate), LiCF3SO3 (lithium triflate, LiTf), LiC104 (lithium perchlorate) or a mixture of salts.

10. A method for preparing a hybrid solid electrolyte according to any one of claims 1 to 9 comprising the steps of: - Desiccant pre-treatment of an oxide-type ceramic having an atomic percentage of oxygen in the hydroxyl functions %O(OH);, so as to obtain a pre-treated ceramic having an atomic percentage of oxygen present in the surface hydroxyl functions %O(OH)f, said percentages being measured by XPS, and such that the ratio %0(0H)f / %0(0H); is between 20 and 60%, and - Contacting the ceramic thus pre-treated with an ionically conductive polymer.

11. Method according to claim 10 such that the desiccant treatment comprises the heat treatment of the ceramic at a temperature between 100 and 700°C, preferably between 200 and 400°C.

12. A method according to claim 10 or 11 such that the desiccant pre-treatment comprises immersing the ceramic in a hydrophilic and polar solvent.

13. Process according to any one of claims 10 to 12 comprising the prior step of preparing the polymer by dry and / or solvent route.

14. A method for improving the interfacial resistance of a ceramic / polymer hybrid solid electrolyte such that the ceramic is of the oxide type and such that the polymer is ionically conductive, said method comprising: the preliminary desiccant treatment of said oxide type ceramic having an atomic percentage of oxygen in the hydroxyl functions %O(OH);, so as to obtain a pre-treated ceramic having an atomic percentage of oxygen present in the surface hydroxyl functions %O(OH)f, said percentages being measured by XPS, and such that the ratio %O(OH)f / %O(OH)i is between 20 and 60%, and the mixing of the ceramic thus pre-treated with the ionically conductive polymer.

15. An electrochemical element comprising a hybrid solid electrolyte according to any one of claims 1 to 9.

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