Low-temperature crystallization of an oxide-type ceramic electrolyte enabling the assembly of composites

Abstract

Low-temperature crystallization of an oxide-type ceramic electrolyte for composite assembly. The present invention relates to a process for preparing a solid electrolyte material, comprising: - a step of preparing an initial composition comprising at least one oxide-based ceramic material M, said material M being in a glassy state, - a step of densifying the initial composition and obtaining a densified composition, and - a step of crystallizing the material M in the glassy state, comprising heating the densified composition to a temperature strictly above the glass transition temperature of the material M in the glassy state. Figure for abstract: None

Description

Title of the invention: Low temperature crystallization of an oxide-type ceramic electrolyte allowing the assembly of composites

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

[0002] "Conventional" lithium batteries have high energy densities and are used for both mobile applications (portable electronics, electric vehicles) and stationary applications. Lithium batteries are based on the reversible exchange of lithium ions between the positive and negative electrodes. These are separated by an ion-conducting electrolyte. The most common electrolytes include organic solvents mixed with lithium salts. They are toxic, flammable and can compromise battery safety due to the risk of thermal runaway.

[0003] In order to move to a new generation of batteries to equip the next generations of electric vehicles, it is necessary to develop high-performance and safe batteries, i.e. non-flammable, non-toxic and with good ionic conductivities at the operating temperature. In order to ensure good performance for such batteries, it is necessary to ensure both good mechanical properties using a dense medium and a continuous medium for the lithium ions, to ensure the transport of the lithium ions from each particle inside the electrodes to the particles of the other electrode.

[0004] In this context, solid electrolytes have been developed to design all-solid-state batteries. There are two categories of solid electrolytes: polymers and inorganic electrolytes. Polymers demonstrate good performance, especially against metallic lithium, which is considered the ultimate negative electrode, but suffer from a low lithium transport number and limited performance against high-potential positive electrodes. Regarding inorganic electrolytes, there are two types: sulfur-based electrolytes and oxide-based ceramic electrolytes. Sulfur-based electrolytes can be assembled easily and have ionic conductivities comparable to liquid electrolytes, but exhibit high toxicity due to the release of H2S when exposed to moisture, and reduced potential windows.On the other hand, ceramic oxide electrolytes are of interest for their good ionic conductivity, good electronic insulation, non-toxicity, flammability, wide electrochemical stability window and lithium transport number equal to 1. The . The best ionic conductors are made from crystalline materials with values ​​above 105 S / cm at room temperature.

[0005] The preparation of an oxide-based electrolyte material conventionally comprises sintering (a high-temperature heat treatment) the oxide powders in crystalline form, in order to form a dense and continuous medium ensuring the transport of lithium ions from one electrode to another. In the case of the preparation of a complete cell, the electrolyte in the form of crystalline powder is incorporated into the composition of the electrodes, and is also placed as a separator between the electrodes, and then this assembly is sintered.

[0006] However, these sintering processes almost systematically lead to reactions between the electrolyte and the active material at the interfaces, which results in the degradation of the materials and the loss of their electrochemical properties.

[0007] Furthermore, there are very few examples of all-solid-state batteries comprising an oxide-based electrolyte material with thick electrodes, because their low formability makes cell assembly difficult.

[0008] There is therefore a need for a method for preparing an oxide-based electrolyte material that makes it possible to obtain a dense electrolyte material having both high density and high ionic conductivity.

[0009] There is also a need for a method for preparing an oxide-based electrolyte material that makes it possible to obtain an electrode and / or a separator and / or an all-solid-state battery having a high thickness.

[0010] The present invention therefore relates to a process for preparing a solid electrolyte material, comprising:

[0011] - a step of preparing an initial composition comprising at least one ceramic material based on oxide M, said material M being in a glassy state,

[0012] - a step of densifying the initial composition and obtaining a com densified position, and

[0013] - a step of crystallization of the material M in the glassy state, comprising heating of the densified composition up to a temperature strictly higher than the glass transition temperature of the material M in the glassy state.

[0014] Indeed, the inventors have surprisingly discovered that starting from a composition comprising the oxide-based material M in the vitreous state, it is possible to densify it at a lower temperature compared to an initial composition which would comprise only the material M in the crystalline state. By crystallizing the vitreous material during or after densification, it is possible to obtain a system which is both dense and ionically conductive. Reducing the densification and / or crystallization temperature makes it possible to avoid losses in electrochemical performance, but also to reduce the costs of possible industrial production. This therefore makes it possible to broaden the range of compatible electrolyte materials for assemblies with at least half an all-ceramic cell, since materials that normally require high sintering temperatures (Garnets, Perovskite, NASICON, etc.) could be considered without the risk of causing chemical reactions between the components. In addition, lowering the densification and / or crystallization temperature makes it possible to limit thermal expansion and its undesirable effects on the mechanical strength of a multilayer system, such as the appearance of cracks during the heating or cooling process, which makes it possible to broaden the spectrum of compatible ceramic electrolyte materials and active electrode materials.

[0015] According to the invention, a material in the vitreous state is an amorphous material which has a glass transition temperature Tg. A material is considered amorphous when a halo is obtained during X-ray diffraction. The amorphous state can be demonstrated by the absence of localized diffraction peaks during X-ray powder diffraction. The presence of a glass transition temperature can be verified by differential scanning calorimetry or differential thermal analysis.

[0016] Preferably, the crystallization step comprises heating the densified composition to a temperature strictly higher than the glass transition temperature of the material M in the glassy state until at least 99% by weight of the material M in the glassy state has been crystallized relative to the total weight of material M in the glassy state of the initial composition, preferably 100% by weight. Preferably, the method according to the invention comprises a step of obtaining a material M in the crystalline state, preferably single-phase.

[0017] Throughout the description, all technically possible combinations of preferred embodiments and / or features are also described.

[0018] Preferably, in the method according to the invention:

[0019] - the densification step is carried out at a pressure between 1 MPa and 1000 MPa, preferably between 30 MPa and 500 MPa, preferably between 50 and 250 MPa, preferably between 80 MPa and 150 MPa, preferably between 90 MPa and 110 MPa, and / or

[0020] - the crystallization step is carried out at a pressure between 0 MPa and 1000 MPa, preferably between 0.1 MPa and 1000 MPa, preferably between 30 MPa and 500 MPa, preferably between 50 and 250 MPa, preferably between 80 MPa and 150 MPa, preferably between 90 MPa and 110 MPa, and / or

[0021] - the densification and crystallization steps are carried out at a pressure between 1 MPa and 1000 MPa, preferably between 30 MPa and 500 MPa, preferably between 50 and 250 MPa, preferably between 80 MPa and 150 MPa, preferably between 90 MPa and 110 MPa, and / or

[0022] - the densification step is carried out at a temperature within a range [a*Tg; b*Tg], Tg being the glass transition temperature of the material M in the glassy state, and a being equal to 0.78, preferably equal to 0.84, advantageously equal to 0.91, and b being equal to 1.09, preferably equal to 1.05, preferentially equal to 1.02, advantageously equal to 1.01, and / or

[0023] - the densification step is carried out at a temperature between 473 K and 1073 K, preferably between 673 K and 843 K, preferably between 713 K and 823 K, advantageously between 733 K and 813 K and / or

[0024] - the crystallization step is carried out at a temperature greater than or equal to the temperature for carrying out the densification step and / or at a temperature within an interval [c*Tx; d*Tx], Tx being the crystallization temperature of the material M in the glassy state, and c being equal to 0.70, preferably equal to 0.75, preferably equal to 0.80, advantageously equal to 0.82, more advantageously equal to 0.83, and d being equal to 1.15, preferably equal to 1.01, preferentially equal to 0.92, advantageously equal to 0.91, and / or

[0025] - the crystallization step is carried out at a temperature between 473 K and 1073 K, preferably between 713 K and 903 K, advantageously between 743 K and 813 K and / or

[0026] - the densification and crystallization step are carried out at a temperature included in an interval [a*Tg; d*Tx], Tg being the glass transition temperature of the material M in the glassy state and Tx being the crystallization temperature of the material M in the glassy state, a being equal to 0.78, preferably equal to 0.84, advantageously equal to 0.91, and d being equal to 1.15, preferably equal to 1.01, preferentially equal to 0.92, advantageously equal to 0.91 and / or

[0027] - the densification and crystallization steps are carried out at a temperature between 473 K and 1073 K, preferably between 673 K and 903 K, advantageously between 733 K and 813 K,

[0028] it being understood that these preferred embodiments apply in isolation, or according to each of their technically possible combinations, in combinations with all the embodiments of the method of the invention.

[0029] Preferably, the densification step and / or the crystallization step are carried out by hot isostatic pressing or by flash sintering, preferably by hot isostatic pressing.

[0030] Preferably, the glass transition temperature of the material M in the glassy state Tg is less than or equal to the sintering temperature of the material M in the crystalline state.

[0031] Preferably, the crystallization temperature of the material M in the glassy state Tx is less than or equal to the sintering temperature of the material M in the crystalline state.

[0032] By sintering temperature of the material M in the crystalline state, we mean the temperature necessary to densify a powder of the material M in the crystalline state. The temperature necessary to densify a powder of the material M in the crystalline state is preferably within an interval [h*Tf; j*Tf], Tf being the melting temperature of the material M in the crystalline state, and h being equal to 0.60, preferably equal to 0.70, advantageously equal to 0.78, and j being equal to 0.95, preferably equal to 0.85, advantageously equal to 0.82.

[0033] Preferably, the material M in the glassy state has at least one crystallization temperature Tx. The kinetics of crystallization must be sufficiently high to allow crystallization at a temperature lower than the sintering temperature of the crystallized material. The crystallization temperature can be characterized by differential scanning calorimetry or differential thermal analysis.

[0034] Unless explicitly stated otherwise, all temperatures, in particular glass transition, crystallization and melting temperatures, are expressed in degrees Kelvin.

[0035] The glass transition temperatures Tg and crystallization temperatures Tx of the material M in the glassy state are for example determined by differential scanning calorimetry, using the following method: a sample of approximately 10 mg is heated at a rate of 10°C / min from room temperature until the material melts. The change of state caused by the glass transition causes an inflection of the heat flow curve with respect to the temperature, the intersection between the extension of the baseline before the transition and the tangent at the inflection point makes it possible to define the glass transition temperature Tg. The change of state caused by crystallization results in an exothermic peak, the intersection between the extension of the baseline before crystallization and the tangent to the curve after the start of the crystallization peak makes it possible to define Tx.Since the melting of the material results in an endothermic peak, the intersection between the extension of the baseline before melting and the tangent to the curve after the start of melting allows the temperature Tf to be defined.

[0036] Preferably, the material M corresponds to the formula (I):

[0037] M®x(1) MWX(U) Ma®x(111) M»® (IV) M%V) M(vi)x(vl)Oy(O) (I)

[0038] in which

[0039] 1 < y(O) < 20,

[0040] M®, M(IV), M(V) and M(VI) represent a cation or a mixture of cations respectively of oxidation state (I), (II), (III), (IV), (V) and (VI),

[0041] x(I), x(II), x(III), x(IV), x(V) and x(VI) represent, respectively, the fraction molar in the material of formula (I) of the cation(s) M®, M(IV), M(V) and M <VI\

[0042] with x(I), x(II), x(III), x(IV), x(V) and x(VI) each being greater than or equal to 0 and less than or equal to 4,

[0043] provided that at least one of x(I), x(II), x(III), x(IV), x(V) and x(VI) is non-zero, and that the values ​​of x(I), x(II), x(III), x(IV), x(V) and x(VI) are such that the material (I) is electroneutral.

[0044] By electroneutral material is meant that the sum of the charges carried by each charged element of the material, each charge being weighted by the molar content of the corresponding charged element, is zero.

[0045] Preferably, in the material of formula (I),

[0046] [Math.l] dO = .......-5............

[0047] x(i) being the molar fraction in the material of formula (I) of the cation(s) M(i) and D0(M(i)) being the value of the oxidation state of the cation(s) M(i).

[0048] The value of the oxidation state of the cation(s) M® is 1, the value of the oxidation state of the cation(s) M(II) is 2, the value of the oxidation state of the cation(s) M(IV) is 3, the value of the oxidation state of the cation(s) M(V) is 4, the value of the oxidation state of the cation(s) M(V) is 5 and the value of the oxidation state of the cation(s) M(VI) is 6.

[0049] Preferably, 4 < y(O) < 18, preferably 8 < y(O) < 16, preferably 10 < y(O) <14, advantageously y (O) = 12.

[0050] Preferably, M(I) is selected from Li, Na, K, Cs and any of their mixtures, and / or M(II) is selected from Mg, Ca, Ba, Zn, Pb, Fe, Sr and any of their mixtures, and / or M(III) is selected from Fe, Al, B, Ti, Cr and any of their mixtures, and / or M(IV) is selected from Ti, Zr, Si, Ge, V and any of their mixtures, and / or M(V) is selected from P, V or their mixtures, and / or M(VI) is Mo.

[0051] When M(I), M(II), M(III), M(IV), M(V) or M(VI) is a mixture of at least two elements chosen from the lists above, the corresponding molar fraction x(I), x(II), x(III), x(IV), x(V) or x(VI) is equal to the sum of the molar fractions of each element constituting the mixture.

[0052] According to one embodiment, at least two of x(I), x(II), x(III), x(IV), x(V) and x(VI) are unharmed, preferably two of x(I), x(II), x(III), x(IV), x(V) and x(VI) are unharmed.

[0053] According to another embodiment, at least three of x(I), x(II), x(III), x(IV), x(V) and x(VI) are unharmed, preferably three of x(I), x(II), x(III), x(IV), x(V) and x(VI) are unharmed.

[0054] According to another embodiment, at least four of x(I), x(II), x(III), x(IV), x(V) and x(VI) are unharmed, preferably four of x(I), x(II), x(III), x(IV), x(V) and x(VI) are unharmed.

[0055] According to another embodiment, at least five of x(I), x(II), x(III), x(IV), x(V) and x(VI) are unharmed, preferably five of x(I), x(II), x(III), x(IV), x(V) and x(VI) are unharmed.

[0056] Preferably, in the material of formula (I), x(II) and x(VI) are null and x(I), x(III), x(IV) and x(V) are unnull.

[0057] Preferably, 1.2 < x(I) < 1.8, preferably 1.4 < x(I) < 1.6, and / or 0.2 < x(III) < 0.8, preferably 0.4 < x(III) < 0.6, and / or 1.2 < x(IV) < 1.8, preferably 1.4 < x(IV) < 1.6, and / or 2.5 < x(V) < 3.5, preferably 2.8 < x(V) < 3.2.

[0058] More preferably, the material of formula (I) is a material of formula (!')

[0059] M(I)i+2w+x_y.JS4(II)wM(III\M(v\M(IVAw-xy(SiO4)z(PO

[0060] in which

[0061] M®, M(IV) are as defined above,

[0062] 0 < w < 2, preferably 0 < w < 1, preferably w is equal to 0,

[0063] 0 < x < 2, preferably 0 < x < 1, preferably 0.2 < x < 0.8, preferably 0.4 < x < 0.6, preferably x is equal to 0.5,

[0064] 0 < y < 2, preferably 0 < y < 1, preferably y is equal to 0, and

[0065] 0 < z < 3, preferably 0 < z < 1, preferably z is equal to 0.

[0066] Advantageously, the material of formula (I) is a material of formula (I”)

[0067] Lii+qAlqM <IVAq(PO4)3 (I”)

[0068] in which 0 < q < 0.8, preferably 0.3 < q < 0.7, preferably 0.4 < q < 0.6, preferably q is equal to 0.5, and M(IV) is as defined above, preferably chosen from Ge and Ti.

[0069] Preferably, in the method according to the invention, the material M in the vitreous state is in the form of a powder whose particle size is less than or equal to 100 pm, preferably less than or equal to 80 pm, preferably less than or equal to 50 pm, more preferably less than or equal to 20 pm, advantageously between 0.1 pm and 100 pm.

[0070] Such a particle size makes it possible to improve the efficiency of the process because it makes it possible to better coat the other particles present in the initial composition (for example the particles of active material) and also to reduce the crystallization temperature of the material M in the vitreous state by increasing the number of nucleation sites on the surface.

[0071] Preferably, the initial composition comprises at least 11% by mass, preferably at least 30% by mass, more preferably at least 50% by mass, advantageously at least 70% by mass of the material M in the vitreous state relative to the total mass of the composition, preferably comprises from 11% to 100% by mass, preferably from 50% to 98% by mass of the material M in the vitreous state relative to the total mass of the composition.

[0072] According to one embodiment, the initial composition consists of the material M in the vitreous state.

[0073] According to another embodiment, the initial composition further comprises the material M in the crystalline state. According to this embodiment, the initial composition comprises from 11% to 99% by mass, preferably from 30 to 98% by mass, preferentially from 50 to 95%, more preferentially from 70 to 90% by mass, advantageously from 75 to 85% of the material M in the vitreous state relative to the total mass of the composition. According to this embodiment, the initial composition comprises from 1% to 89% by mass, preferably from 2% to 70% by mass, preferentially from 5 to 50%, more preferentially from 10 to 30% by mass of the material M in the crystalline state relative to the total mass of the composition.

[0074] Preferably, according to this embodiment, the initial composition consists of the material M in the vitreous state and the material M in the crystalline state, preferably in any one of the proportions defined above.

[0075] The use of material M in the crystalline state having the same composition as material M in the vitreous state makes it possible to avoid the addition of a new phase with a different composition which would limit ionic conduction and / or could react with the active material, if present in the initial composition.

[0076] According to one embodiment, the densification step and the crystallization step are simultaneous.

[0077] This embodiment is advantageous in that it allows the vitreous phase to compensate for part of the porosities formed by the differences in density between the vitreous phase and the crystalline phase of the material M. Indeed, the residual vitreous phase (which crystallizes little by little) is deformable and therefore partly fills the porosities which form at the same time. The latter are formed in the (frequent) cases where the crystallized material has a higher density than the vitreous material.

[0078] Preferably, according to this embodiment, the crystallization temperature Tx of the material M in the glassy state is equal to Tg + a, Tg being the glass transition temperature of the material M in the glassy state, and a being less than or equal to 200 K, preferably less than or equal to 100 K, preferably between 10 K and 200 K.

[0079] According to another embodiment, the densification step is carried out before the crystallization step.

[0080] Preferably, according to this embodiment, the crystallization temperature Tx of the material M in the glassy state is equal to Tg + [3, Tg being the glass transition temperature of the material M in the glassy state, and [3 being greater than or equal to 300 K, preferably greater than or equal to 400 K, preferably between 300 and 1000 K.

[0081] According to one embodiment, the initial composition further comprises an active material and an electronic conductor.

[0082] The implementation of such a method makes it possible to prepare a solid electrolyte material included in an electrode. The implementation of such a method preferably makes it possible to prepare an all-solid electrode.

[0083] The electronically conductive material is generally chosen from graphite, carbon black, acetylene black, soot, graphene, carbon nanotubes or fibers or a mixture thereof. It may also be chosen from titanium nitride, or metals such as aluminum or gold.

[0084] The active material is that typically used in cation batteries H+, Li+, Na+, K+, Ca2+, Mg2+, Ag+, Zn2+.

[0085] Active materials typically used in lithium batteries are, for example, olivines LiMPO4 with (M being chosen from Fe, Mn, Co, Ni and any of their mixtures), LiNixMnyCozO2 with x+y+z=l, LiNio.soCoo 15AI0.05O2 and LiNio.5Mn1.5O4 as positive electrodes and LiTi2(PO4)3, or generally oxides. In particular, active materials or electronic additives in glassy form, capable of crystallizing or not during heat treatment, could be used. For example, LiTi2(PO4)3.

[0086] In the case of a negative electrode, the negative electrode active material is not particularly limited. It can be selected from the following groups and mixtures thereof: - Graphite - Silicon - metals such as Ge, Si, Sn, Li or generally oxides, - a metal strip or a chemically stable metal alloy with the other components during the densification and crystallization stages whose surface is free of the active metal, for example lithium metal, before charging the element and is covered with a layer of the active metal, for example lithium, during charging of the element, - a titanium and / or niobium oxide TNG having the formula:

[0087] LixTia_yMyNbb_zM' zO((X+4a+5b) / 2)_c-dXc

[0088] where0 <x<5;0<y<l;0<z<2;l<a<5;l<b<25; 0,25 <a / b<2;0<c< 2 and 0 < d < 2; ay > 0; bz > 0;

[0089] M and M' each independently represent at least one element selected from the group consisting of Li, 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 and Sm;

[0090] X represents at least one element selected from the group consisting of S, F, Cl and Br.

[0091] The index d represents an oxygen vacancy. The index d can be less than or equal to 0.5.

[0092] Said at least one titanium and niobium oxide may be chosen from TiNb2O7, Ti2 Nb2O7>Ti2Nb2O9 and Ti2Nbi0O29.

[0093] - a lithiated titanium oxide or a titanium oxide capable of being lithiated. The oxide of lithium titanium is chosen from the following oxides:

[0094] i) Lix_aMaTiy_bM'bO4_c_dXc in which 0 <x<3 ; l<y<2,5 ; 0<a<l ; 0<b<l ; 0<c<2 et -2,5<d<2,5 ;

[0095] M represents at least one element selected from the group consisting of Na, K, Mg, Ca, B, Mn, Fe, Co, Cr, Ni, Al, Cu, Ag, Pr, Y and La;

[0096] M' represents at least one element selected from the group consisting of B, Mo, Mn, Ce, Sn, Zr, Si, W, V, Ta, Sb, Nb, Ru, Ag, Fe, Co, Ni, Zn, Al, Cr, La, Pr, Bi, Sc, Eu, Sm, Gd, Ti, Ce, Y and Eu;

[0097] X represents at least one element selected from the group consisting of S, F, Cl and Br;

[0098] The index d represents an oxygen vacancy. The index d can be less than or equal to 0.5.

[0099] ii) HxTiyO4 in which 0 <x<l ; 0<y<2, et

[0100] iii) a mixture of compounds i) to ii).

[0101] Examples of lithiated titanium oxides belonging to group i) are spinel Li4 Ti50i2, Li2TiO3 laramsdellite Li2Ti3O7,LiTi2O4, LixTi2O4, with 0 <x<2 et Li2Na2Ti60i4.

[0102] Un composé LTO préféré a pour formule Li4 _aMaTi5.bM’bO4> for example Li4Ti50i2 which is also written Li4 / 3Ti5 / 3O4.

[0103] Certain other negative electrode active materials may be added after the implementation of the method according to the invention, i.e. by placing a strip against the electrolyte part of the assembly prepared according to the invention. A polymer separator (or not) may be interposed between the strip and the electrolyte prepared according to the invention in order to ensure the electrochemical stability of the system. These are, for example, materials such as:

[0104] - a metal or a metal alloy, in particular lithium or an alloy of lithium,

[0105] - a strip whose surface is free from the active metal, for example free from lithium, before the element is charged and is covered with a layer of the active metal, for example lithium, during the charging of the element

[0106] - a composite electrode material composed of an electrode active material negative, an electronic conductor and an ion-conducting polymer.

[0107] The term "negative electrode" designates when the accumulator is discharging, the electrode functioning as an anode and when the accumulator is charging, the electrode functioning as a cathode, the anode being defined as the electrode where an electrochemical oxidation reaction takes place (emission of electrons), while the cathode is the seat of the reduction.

[0108] In the case of a positive electrode, the positive electrode active material is not particularly limited. It may be selected from the following groups or mixtures thereof:

[0109] - a compound (a) of formula LixMi_y_z_wM'yM”zM'”w02 (LM02) where M, M', M” and M”' are selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, W and Mo provided that at least M or M' or M'' or M”' is selected from Mn, Co, Ni, or Fe; M, M', M” and M”' being different from each other; and 0.8 <x<l,4 ; 0<y<0,5 ; 0<z<0,5 ; 0<w<0,2 et x+y+z+w<2,l ;

[0110] - a compound (b) of formula LixMn2_y zM'yM"zO4 (LMO), where M' and M" are chosen in 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 ;

[0111] - a compound (c) of formula LixFei yMyPO4(LFMP) where M is chosen from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo; and 0.8 <x<l,2 ; 0<y<0,6 ;

[0112] - a compound (d) of formula LixMni y zM'yM”zP04 (LMP), where M' and M” are different from each other and are selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo, with 0.8 <x<l,2 ; 0<y<0,6 ; 0<z<0,2 ;

[0113] - a compound (e) of formula xLi2MnO3; (lx)LiM02 where M is at least one element chosen from Ni, Co and Mn and x <l.

[0114] - a compound (f) of formula Li|+xMO2 yFy of cubic structure where M represents at least one element selected from the group consisting of 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 and Sm and where 0 < x < 0.5 and 0 < y < 1.

[0115] - a compound (g) of the LiVPO4F (LVPF) type.

[0116] The term "positive electrode" designates when the accumulator is discharging, the electrode functioning as a cathode and when the accumulator is charging, the electrode functioning as an anode.

[0117] According to a particular embodiment, the initial composition may further comprise a sacrificial polymer. The presence of a sacrificial polymer makes it possible to shape the different layers. The shaping may then be carried out by tape casting or by another method. If a sacrificial polymer is added to the composition of the layers, it is then necessary to add a treatment after shaping the stack to remove the polymer. The sacrificial polymer is preferably chosen from polycarbonates, such as propylene carbonate, binders, such as cellulose ethers, vinyl or acrylic type polymers, plasticizers, such as glycols, and dispersants.

[0118] The method according to the invention therefore comprises, according to a particular embodiment, a step of shaping the initial composition by casting into a strip, between the preparation step and the densification step.

[0119] According to one embodiment of the method according to the invention, the initial composition is a first composition comprising at least one first ceramic material based on oxide M, said first material M being in a glassy state, and further comprising the following steps:

[0120] - the preparation of a second composition comprising at least a second ceramic material based on oxide M', identical to or different from the first material M, said second material M' being in a vitreous or crystalline state,

[0121] - the preparation of a stack comprising a first layer obtained from of the first composition and a second layer obtained from the second composition,

[0122] wherein the densifying step comprises densifying the stack and obtaining a densified stack, and

[0123] wherein the crystallization step comprises heating the densified stack to a temperature strictly higher than the glass transition temperature of the material M in the glassy state or the glass transition temperature of the material M' in the glassy state.

[0124] Preferably, the first composition or the second composition further comprises at least one active material and an electronic conductor.

[0125] Advantageously, the material M and the material M' are in a glassy state.

[0126] The implementation of such a method makes it possible in particular to prepare an all-solid-state battery in the form of a bilayer monoblock consisting of a ceramic electrolyte (CE) layer and a composite electrode layer.

[0127] In particular:

[0128] the material M in the glassy state is defined by a glass transition temperature Tg(M) and a crystallization temperature TC(M), the material M' in the glassy state is defined by a glass transition temperature Tg(M') and a crystallization temperature TC(M'), and the material M' in the crystalline state is defined by a sintering temperature Tfritt(M'), as defined above. We define by (Ensl) the set consisting of:

[0129] - (Tg(M); Tg(M')) if the materials M and M' are in the glassy state in the assembly, Or

[0130] - (Tg(M); Tfritt(M')) if the material M is in the glassy state and the material M' is in the crystalline in the assembly.

[0131] Furthermore, we define by (Ens2) the set consisting of:

[0132] - (TC(M); TC(M')) if the materials M and M' are in the glassy state in the assembly, Or

[0133] - (TC(M) ; Tfritt(M')) if the material M is in the glassy state and the material M' is in the crystalline in the assembly.

[0134] Preferably:

[0135] - the densification step is preferably carried out at a temperature included in an interval [a*T'; b*T'], a being equal to 0.78, preferably equal to 0.84, advantageously equal to 0.91, b being equal to 1.09, preferably equal to 1.05, preferentially equal to 1.02, advantageously equal to 1.01, and T' being the maximum temperature of the assembly (Ensl) and / or

[0136] - the crystallization step is carried out at a temperature greater than or equal to the temperature for implementing the densification step and / or at a temperature within an interval [c*T”; d*T”], c being equal to 0.70, preferably equal to 0.75, preferably equal to 0.80, advantageously equal to 0.82, more advantageously equal to 0.83, and d being equal to 1.15, preferably equal to 1.01, preferentially equal to 0.92, advantageously equal to 0.91, and T” being the maximum temperature of the assembly (Ens2).

[0137] According to one embodiment of the method according to the invention, the composition is a first composition comprising at least one first ceramic material based on oxide M, said first material M being in a glassy state, and further comprises the following steps:

[0138] - the preparation of a second composition comprising at least a first active material, a first electronic conductor, and a second ceramic material based on oxide M', identical to or different from the first material M, said second material M' being in a glassy or crystalline state,

[0139] - the preparation of a third composition comprising at least a second active material, a second electronic conductor, and a third oxide-based ceramic material M”, identical to or different from the first material M and / or the second material M', said third material M” being in a glassy or crystalline state,

[0140] - the preparation of a stack comprising a first layer obtained from of the first composition, a second layer obtained from the second composition, and a third layer obtained from the third composition,

[0141] wherein the densification step comprises densifying the stack and obtaining a densified stack, and

[0142] wherein the crystallization step comprises heating the densified stack to a temperature strictly higher than a temperature being the highest temperature among the glass transition temperature of the material M in the glassy state, the glass transition temperature of the material M' in the glassy state and the glass transition temperature of the material M” in the glassy state.

[0143] Preferably, two compositions among the first composition, the second composition and the third composition each independently further comprise at least one active material and one electronic conductor.

[0144] Advantageously, the first layer of the stack is arranged between the second layer and the third layer, the second composition comprises at least a first active material and a first electronic conductor, and the third composition comprises at least a second active material and a second electronic conductor material.

[0145] The implementation of such a method makes it possible in particular to prepare an all-solid-state battery in the form of a three-layer monoblock consisting of a layer of ceramic electrolyte (CE) and two layers of composite electrode.

[0146] Preferably, the material M, the material M' and the material M” are in a glassy state.

[0147] Preferably, for each of these two embodiments, the material M, the material M', and the material M” when present, are independently a material of formula (I) or (!') or (I”) as defined in the present application.

[0148] All of the preferred characteristics and embodiments of the method according to the invention apply to the two embodiments above.

[0149] In particular:

[0150] the material M in the glassy state is defined by a glass transition temperature Tg(M) and a crystallization temperature TC(M), the material M' in the glassy state is defined by a glass transition temperature Tg(M') and a crystallization temperature TC(M'), the material M” in the glassy state is defined by a glass transition temperature Tg(M”) and a crystallization temperature TC(M”), the material M' in the crystalline state is defined by a sintering temperature Tfritt(M') and the material M” in the crystalline state is defined by a sintering temperature Tfritt(M”), determined according to the method described above.

[0151] We define by (Set3) the set consisting of:

[0152] - (Tg(M); Tg(M'); Tg(M”)) if the materials M, M' and M” are in the glassy state in the assembly, or

[0153] - (Tg(M); Tfritt(M'); Tfritt(M”)) if the material M is in the glassy state and the materials M' and M” are in the crystalline state in the assembly, or

[0154] - (Tg(M); Tg(M'); Tfritt(M”)) if the materials M and M' are in the glassy state and the material M” is in the crystalline state in the assembly, or

[0155] - (Tg(M); Tfritt(M'); Tg(M”)) if the materials M and M” are in the glassy state and the material M' is in the crystalline state in the assembly.

[0156] Furthermore, we define by (Set4) the set consisting of:

[0157] - (TC(M); TC(M'); TC(M”)) if the materials M, M' and M” are in the glassy state in the assembly, or

[0158] - (TC(M); Tfritt(M'); Tfritt(M”)) if the material M is in the glassy state and the materials M' and M” are in the crystalline state in the assembly, or

[0159] - (TC(M); TC(M'); Tfritt(M”)) if the materials M and M' are in the glassy state and the material M” is in the crystalline state in the assembly, or

[0160] - (TC(M); Tfritt(M'); TC(M”)) if the materials M and M” are in the glassy state and the material M' is in the crystalline state in the assembly.

[0161] According to this embodiment:

[0162] - the densification step is preferably carried out at a temperature included in an interval [a*T'; b*T'], a being equal to 0.78, preferably equal to 0.84, advantageously equal to 0.91, b being equal to 1.09, preferably equal to 1.05, preferentially equal to 1.02, advantageously equal to 1.01, and T' being the maximum temperature of the assembly (Ens3) and / or

[0163] - the crystallization step is carried out at a temperature greater than or equal to the temperature for implementing the densification step and / or at a temperature within an interval [c*T”; d*T”], c being equal to 0.70, preferably equal to 0.75, preferably equal to 0.80, advantageously equal to 0.82, more advantageously equal to 0.83, and d being equal to 1.15, preferably equal to 1.01, preferentially equal to 0.92, advantageously equal to 0.91, and T” being the maximum temperature of the assembly (Ens4).

[0164] More generally, an embodiment of the method according to the invention can be defined, in which the initial composition comprising the oxide-based ceramic material is a first composition, the method further comprising the following steps:

[0165] - the preparation of p compositions each independently comprising a material ceramic based on oxide Mp, the material(s) Mp being identical or different from each other and identical or different from the first material M, p being an integer ranging from 1 to 8, q material(s) Mp among the p material(s) Mp being in a glassy state and (pq) material(s) Mp among the p material(s) Mp being in a crystalline state, q being an integer ranging from 0 to 8,

[0166] - the preparation of a stack comprising a first layer obtained from of the first composition, and p layers obtained from the p compositions, respectively,

[0167] wherein the densifying step comprises densifying the stack and obtaining a densified stack, and

[0168] wherein the crystallization step comprises heating the densified stack to a temperature strictly higher than a temperature being the highest temperature among the glass transition temperature of the material M in the glassy state and the glass transition temperature(s) of the q material(s) Mp in the glassy state.

[0169] q is less than or equal to p.

[0170] Preferably, p is an integer ranging from 1 to 6, preferably ranging from 1 to 5, more preferably ranging from 1 to 4, more preferably ranging from 1 to 3, even more preferably is equal to 2, 3, 4 or 5, advantageously is equal to 2 or 3.

[0171] Preferably, the material(s) Mp is (are) in a glassy state.

[0172] Preferably, the material M and the material(s) Mp is (are) independently a material of formula (I) or (!') or (I”) as defined in the present application.

[0173] All of the preferred characteristics and embodiments of the method according to the invention apply to this embodiment.

[0174] In particular:

[0175] the material M in the glassy state is defined by a glass transition temperature Tg(M) and a crystallization temperature TC(M), the q material(s) Mp in the glassy state is(are) each independently defined by a glass transition temperature Tg(Mp) and a crystallization temperature TC(MP), and the (pq) material(s) Mp in the crystalline state is(are) each independently defined by a sintering temperature Tfritt(Mp). The temperatures Tc, Tg and Tfritt are determined according to the methods described above.

[0176] We define by (Ens) the set of (p+1) temperatures consisting of the glass transition temperature Tg(M) of the material M in the glassy state, the q glass transition temperatures Tg(Mp) of the materials Mp in the glassy state, and the (pq) sintering temperatures Tfritt(Mp) of the materials Mp in the crystalline state. In other words, (Ens) = (Tg(M); q (Tg(Mp); (pq) Tfntt(Mp)).

[0177] We also define by (Ens)' the set of (p+1) temperatures consisting of the crystallization temperature TC(M) of the material M in the glassy state, the q crystallization temperatures TC(MP) of the materials Mp in the glassy state, and the (pq) sintering temperatures Tfritt(Mp) of the materials Mp in the crystalline state. In other words, (Ens)' = (TC(M); q (TC(MP); (pq) Tfritt(Mp)).

[0178] Preferably:

[0179] - the densification step is carried out at a temperature within a interval [a*T' ; b*T'], a being equal to 0.78, preferably equal to 0.84, advantageously equal to 0.91, b being equal to 1.09, preferably equal to 1.05, preferentially equal to 1.02, advantageously equal to 1.01, T' being the maximum temperature of the assembly (Ens) and / or

[0180] - the crystallization step is carried out at a temperature greater than or equal to the temperature for carrying out the densification step and / or at a temperature within an interval [c*T”; d*T”], c being equal to 0.70, preferably equal to 0.75, preferably equal to 0.80, advantageously equal to 0.82, more advantageously equal to 0.83, and d being equal to 1.15, preferably equal to 1.01, preferentially equal to 0.92, advantageously equal to 0.91, T” being the maximum temperature of the assembly (Ens)'.

[0181] The present invention also relates to a solid electrolyte material capable of being obtained by the method according to the invention.

[0182] Depending on the initial composition, the solid electrolyte material capable of being obtained by the process according to the invention is included in a separator, and / or an electrode for an all-solid battery.

[0183] The present invention also relates to an all-solid electrochemical element comprising the solid electrolyte material capable of being obtained by the method according to the invention.

[0184] Preferably, the all-solid electrochemical element is capable of being obtained by the method according to the invention.

[0185] The term "electrochemical element" means an elementary electrochemical cell consisting of a monobloc assembly of two or three layers of positive electrode / separator (or electrolyte) and possibly a negative electrode, or possibly a tetralayer of positive electrode / electrolyte / electrolyte2 / negative electrode making it possible to store the electrical energy supplied by a chemical reaction and to restore it in the form of current, or a part of such an electrochemical cell, i.e. an electrode or a separator. A metal sheet, for example based on lithium, is used as a negative electrode when a bilayer is produced. A separator based on an ion-conducting polymer can be used to protect the bilayer from possible damage caused by direct contact with the negative electrode.

[0186] In all-solid electrochemical cells, the solid electrolyte material may be included in the separator and / or in the electrodes.

[0187] When the all-solid electrochemical element comprises at least two distinct layers (separator and an electrode, or two electrodes separated by a separator), each layer may comprise identical or different solid electrolyte materials.

[0188] The electrochemical element according to the invention is particularly suitable for lithium accumulators, such as Li-ion, primary Li (non-rechargeable) and Li metal (rechargeable or not), lithium alloy and Li-S accumulators. These materials can also be used in Na-ion, K-ion, Mg-ion or Ca-ion, or Na-metal type accumulators. Figures

[0189] [Fig. 1] [Fig. 1] is a diffractogram of the LAGP material in the glassy state.

[0190] [Fig.2] [Fig.2] is a thermogram obtained by differential scanning calorimetry analysis scanning potential of the LAGP material in the glassy state.

[0191] [Fig.3] [Fig.3] is a diffractogram of the material obtained after shaping according to example 1.

[0192] [Fig.4] [Fig.4] is a diffractogram of the material obtained after shaping according to comparative example 3.

[0193] [Fig.5] [Fig.5] is a diffractogram of the material obtained after shaping according to example 4.

[0194] [Fig.6] [Fig.6] is a diffractogram of the material obtained after shaping according to example 5.

[0195] [Fig.7] [Fig.7] is a diffractogram of the material obtained after shaping according to comparative example 6.

[0196] [Fig.8] [Fig.8] is a curve representing the galvanostatic cycles (cycle 2 to 5) of the cell of example 7, with i = 0.03 mA.cm2 (approximately C / 100) at T = 353 K.

[0197] [Fig.9] [Fig.9] is a curve representing the galvanostatic cycles (cycle 2, 5, 8 and 11) of the cell of example 8, with i = 0.04 mA.cm2 (approximately C / 50) at T = 353 K. Examples Materials and methods

[0198] X-ray diffraction was performed using a Malvem Pa-nalytical Empyrean diffractometer. The points were collected at an angle 20 ranging from 10 to 80° with CuKa radiation (X = 0.15060 nm), every 0.013° with a measurement time of 1 h per scan. The applied voltage and current were 45 kV and 40 mA respectively.

[0199] Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) measurements were performed using a TA SDTQ600. The samples were placed in an alumina crucible under nitrogen flow and the heating ramp applied was 10 K / min.

[0200] Density measurements were performed using a Sartorius density determination kit with an error of 0.1 mg in isopropanol. The density of LAGP glass was performed by helium pycnometry using an AccuPyc II 1340 (Micromeritics) with a 1 cm3 chamber.

[0201] Ionic conductivity measurements were performed at a frequency of 35MHz to 0.04 Hz using a Biology MTZ-35 Impedance Analyzer with an amplitude of 0.01V.

[0202] Lii 5Alo.5Gei 5(PO4)3 (LAGP) is used as electrolyte material.

[0203] This ceramic can be obtained in vitrified and crystalline form. This material has the following properties:

[0204] oion> 104S / cm at room temperature,

[0205] Tf<1573 K

[0206] Tg = 803 K,

[0207] etTx = 891K

[0208] (Vs. T frit,crystal [923-1173] K)

[0209] Crystallization occurs uniformly at a single characteristic temperature.

[0210] Electrochemical stability = [1.85-4.9] V vs. Li / Li+ [0211 ] Abbreviations:

[0212] LAGPv = Vitreous LAGP

[0213] LAGPc = crystalline LAGP

[0214] Tg= Start of the glass transition

[0215] Tx= Start of crystallization peak

[0216] SPS = Spark Plasma Sintering

[0217] Material synthesis:

[0218] LiOH.H2O (>98%, Sigma-Aldrich), A1(OH)3 (>76.5%, Alfa Aesar), GeO2 (>99.999%, Strem Chemicals) and (NH4)2HPO4 (>98%, Sigma-Aldrich) are mixed in a mortar in stoichiometric proportions. The amount of water in A1(OH)3 was previously measured by TGA and is approximately 6% by mass. 5% of LiOH.H2O was added to anticipate lithium losses by evaporation at high temperature. The powder mixture was placed in an alumina crucible and heated to 1473 K at a rate of 10 K / min. The molten liquid is maintained at 1473 K for 1 h to allow the liquid to homogenize. Then, the liquid was soaked in a stainless steel mold at room temperature. The glass pieces were ground using a high-energy mill (SPEX Milm) and 10 mm diameter zirconia balls for 15-30 min. The resulting powder was then sieved to 45 μm.

[0219] The material obtained is amorphous, considering the diffractogram produced after synthesis ([Fig.l]).

[0220] The size of the LAGPv particles is reduced using high-energy grinding and then sieved under 45 pm. The measured Tx is 891.5 ± 0.7 K and the Tg is 803 ± 2 K ([Fig.2]).

[0221] LiFePO4 (LFP, P2) was supplied by Johnson Matthey. LiFe0.25Mno.75P04 (LFMP) was synthesized by melt process (EB Fredj, S. Rousselot, L. Danis, T. Bibienne, M. Gauthier, G. Liang and M. Dollé, 2020, 27, 101116).

[0222] Lowering the forming temperature at SPS of a system with LAGP as electrolyte and an olivine-type active material as active material makes it possible to avoid atomic diffusion and the formation of interfaces between the electrolyte and the active material. These interfaces formed when the forming temperature is 923 K reduce the electrochemical performance of the cell.

[0223] Example 1: Preparation of an electrolyte material for a separator from a composition comprising a material M in the glassy state

[0224] A formulation of 80 / 20% by mass (LAGPv / LAGPc) is formed using Spark plasma sintering (SPS). The applied pressure is 100 MPa. Since the SPS heats with direct current pulses, the temperatures inside the SPS matrix are inhomogeneous. This results in crystallization at a lower average temperature than with natural heating. The higher temperatures are supposedly located at the interfaces between the particles. The temperature program at the SPS includes a ramp of 10 K / min and a plateau at 813 K for 10 minutes. The LAGP is completely crystalline at the end of crystallization and is the only phase present, as shown in [Fig. 3]. The final relative density at 813 K of the separator is 95% and the ionic conductivity is 6.0.105 S.cm1 at T=303 K. Example 2 (comparative):

[0225] Initially 100% crystalline LAGP was formed in SPS using the same method as in Example 1. It has a density of 71% and the measured ionic conductivity is 1.7x105 S.cm1 at T=303 K. Example 3 (comparative):

[0226] 100% glassy LAGP is formed in the SPS. The applied pressure is 100 MPa and the maximum applied temperature is 743 K. As shown by the absence of diffraction peaks in [Fig.4], the separator has not crystallized at this temperature. The relative density is 83% (relative to the density of the glass and not to the crystalline material). Since the glass is an ionic insulator, the final ionic conductivity is less than 10 10S / cm.

[0227] Example 4: Preparation of an electrolyte material for an electrode from a composition comprising a material M in the glassy state

[0228] A composite electrode is shaped using Spark plasma sintering (SPS). The materials used are LAGPv for the electrolyte, carbon-coated LFP for the active material and C65 amorphous carbon particles for electronic conductivity. The formulation tested is 54 / 22 / 24 vol% for LAGP, LFP and C65 respectively. The heating method used is the same as in Example 1. [Fig.5] shows the presence of both LAGPc phases (identified with the similar phase LiGe2 PO4) and LFP after shaping. The final relative density at 813 K of the mixture is 86%. The high electronic conductivity of the mixture prevents a good assessment of the ionic conductivity of the composite. The fact that a solid electrode with mechanical strength can be obtained at such low shaping temperatures (maximum of 813 K) is a completely unexpected result.

[0229] Example 5: Preparation of an electrolyte material for an electrode from a composition comprising a material M in the glassy state

[0230] A composite electrode is shaped using Spark plasma sintering (SPS). The materials used are LAGPv for the electrolyte, carbon-coated LFMP for the active material and C65 amorphous carbon particles for electronic conductivity. The formulation tested is 53 / 22 / 25 vol% for LAGP, LFMP and C65 respectively. The heating method used is the same as in Example 1. [Fig.6] shows the presence of both LAGPc (identified with the similar phase LiGe2 PO4) and LFMP (identified with the similar phase LiMnPO4) phases after shaping. The final relative density at 813 K of the mixture is 90%. The high electronic conductivity of the mixture prevents a good evaluation of the ionic conductivity of the composite. The fact that a solid electrode with mechanical strength could be obtained at such low forming temperatures (maximum 813 K) is a completely unexpected result. Example 6 (comparative):

[0231] An electrode of the same composition as Example 5 is shaped in SPS. The applied pressure is 100 MPa and the maximum applied temperature is 733 K. As shown by the absence of diffraction peaks associated with the LAGP phase in [Fig.7], the electrolyte has not crystallized at this temperature. The relative density is 83%. Since the glass is an ionic insulator, the final ionic conductivity of the electrode is less than 10 10S / cm.

[0232] The results of Examples 1 to 6 are summarized in the table below.

[0233] [Tables 1] Example Initial composition (before shaping in SPS) Theoretical density (g.cm3) Measured density (g.cm3) Compactness (%) Ionic conductivity at T = 303 K of the material after shaping in SPS 1 80 / 20 %mass (LAGPv / LAGPc) 3.42 3.3 95% 6.0.105S.cm* 2 (comparative) 100 %mass LAGPc 3.42 2.42 71% l.7xl05 S.cm i 3 (comparative) 100 %mass LAGPv 3 2.5 83% < 10 10S / cm 4 54 / 22 / 24 %vol LAGPv / LFP / C65 3.09 2.66 86% Nd 5 53 / 22 / 25 %vol LAGPv / LFMP / C65 3.06 2.75 90% Nd 6 (comparative) 54 / 22 / 24 %vol LAGPv / LFP / C65 2.81 2.49 83% < 10 10S / cm Example 7: Preparing a half-stack

[0234] A half-stack is obtained by shaping in SPS, under the conditions of example 1, a stack of a layer of a composition according to example 4 and a layer of a composition according to example 1.

[0235] The half-cell is then polished to reduce the thickness of the electrolyte and electrode to approximately 50 pm and 500 pm respectively. The half-cells were mounted in a Swagelock system based on the publication of A. Kubanska et al. with PEO between the metallic lithium and the LAGP separator to avoid reduction of the LAGP (A. Kubanska, L. Castro, L. Tortet, M. Dollé and R. Bouchet, 2017, 38(2), 189-196). [Fig.8] represents the galvanostatic cycling of this cell. The possibility of cycling thick electrodes with carbon-coated LFP as active material is shown here. The thick electrode allows to obtain surface capacities higher than 4.5 mA.h / cm2 during the first cycles. Example 8: Preparing another half-stack

[0236] Another half-cell is obtained by forming in SPS, under the conditions of Example 1, a stack of a layer of a composition according to Example 5 and a layer of a composition according to Example 1. The half-cell is then polished to reduce the thickness of the electrolyte and the electrode to approximately 90 pm and 190 pm respectively. Just as in Example 7, PEO is placed between the metallic lithium and the LAGP separator. [Fig. 9] represents the galvanostatic cycling of this cell. The possibility of cycling carbon-coated LFMP as active material is shown here.

Claims

Claims

1. A method for preparing a solid electrolyte material, comprising: - a step of preparing an initial composition comprising at least one oxide-based ceramic material M, said material M being in a glassy state, - a step of densifying the initial composition and obtaining a densified composition, and - a step of crystallizing the material M in the glassy state, comprising heating the densified composition to a temperature strictly higher than the glass transition temperature of the material M in the glassy state, and being carried out at a temperature within an interval [c*Tx; d*Tx], Tx being the crystallization temperature, expressed in degrees Kelvin, of the material M in the glassy state, c being equal to 0.70, and d being equal to 0.

92.

2. Method according to claim 1, wherein the densification step is carried out at a pressure between 1 MPa and 1000 MPa, preferably between 30 MPa and 500 MPa, preferably between 50 and 250 MPa, preferably between 80 MPa and 150 MPa, preferably between 90 MPa and 110 MPa.

3. Method according to claim 1 or 2, wherein the densification step is carried out at a temperature within an interval [a*Tg; b*Tg], Tg being the glass transition temperature, expressed in degrees Kelvin, of the material M in the glassy state, and a being equal to 0.78, preferably equal to 0.84, advantageously equal to 0.91, and b being equal to 1.09, preferably equal to 1.05, preferentially equal to 1.02, advantageously equal to 1.

01.

4. A method according to any one of claims 1 to 3, wherein the densification step and the crystallization step are simultaneous.

5. A method according to any one of claims 1 to 3, wherein the densification step is carried out before the crystallization step.

6. A method according to any preceding claim, wherein the glass transition temperature of the material M in the glassy state Tg is less than or equal to the sintering temperature of the material M in the crystalline state.

7. A method according to any one of the preceding claims, wherein the material M corresponds to the formula (I): M®x(1) M^u, M^x(ul) M^ (1V) mw (V) Mn(VI)Oy(O) (I) in which 1 < y(O) < 20, MW, M(IV), M(V) and M(VI) represent a cation or a mixture of cations respectively of oxidation state (I), (II), (III), (IV), (V) and (VI), x(I), x(II), x(III), x(IV), x(V) and x(VI) represent, respectively, the molar fraction in the material of formula (I) of the cation(s) M®, M®, M®, M(IV\ MW and M <VI’, avec x(I), x(II), x(III), x(IV), x(V) et x(VI) étant chacune supérieure ou égale à 0 et inférieure ou égale à 4, à la condition qu’au moins une parmi x(I), x(II), x(III), x(IV), x(V) et x(VI) soit non nulle, et que les valeurs de x(I), x(II), x(III), x(IV), x(V) et x(VI) soient telles que le matériau (I) est électroneutre.

8. A method according to any one of the preceding claims, wherein the initial composition comprises at least 11% by mass of the material M in the vitreous state relative to the total mass of the composition.

9. A method according to any preceding claim, wherein the initial composition consists of material M in the glassy state.

10. A method according to any one of claims 1 to 8, wherein the initial composition further comprises material M in the crystalline state.

11. A method according to any one of the preceding claims, wherein the initial composition comprising the oxide-based ceramic material is a first composition, the method further comprising the following steps: - preparing p compositions each independently comprising an oxide-based ceramic material Mp, the material(s) Mp being identical or different from each other and identical or different from the first material M, p being an integer ranging from 1 to 8, q material(s) Mp among the p material(s) Mp being in a glassy state and (pq) material(s) Mp among the p material(s) Mp being in a crystalline state, q being an integer ranging from 0 to 8, - preparing a stack comprising a first layer obtained from the first composition, and p layers obtained from the p compositions, respectively, wherein the densification step comprises densifying the stack and obtaining a densified stack,and wherein the crystallization step comprises heating, the stack densified up to a temperature strictly higher than a temperature being the highest temperature among the glass transition temperature of the material M in the glassy state, and the glass transition temperature(s) of the q material(s) Mp in the glassy state.

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