Mesoporous electrolytes for thin-film electrochemical devices

Abstract

Thin-film electrolyte in an electrochemical device such as a lithium-ion battery, said electrolyte comprising a porous inorganic layer impregnated with a lithium-ion carrier phase, characterized in that said porous inorganic layer has an interconnected network of open pores.

Description

Furthermore, it is known from Maunel et al. (Polymer 47 (2006) p.5952-5964) that the addition of ceramic fillers in the polymer matrix makes it possible to improve the morphological and electrochemical properties of polymer electrolytes; these ceramic fillers can be active (such as Li2N, LiAI2O3), in which case they participate in the process of transporting lithium ions, or passive (such as AI2O3, SiO2, MgO), in which case they do not participate in the process of transporting lithium ions. The particle size and characteristics of the ceramic fillers influence the electrochemical properties of the electrolytes, see Zhang et al., “Flexible and ion-conducting membrane electrolytes for solid-state lithium batteries: Dispersions of garnet nanoparticles in insulating POE”, NanoEnergy, 28 (2016) p.447-454.However, these membranes are relatively fragile and break easily under the effect of mechanical stresses induced during battery assembly. The present invention seeks to remedy at least in part the drawbacks of the prior art mentioned above. More specifically, the problem that the present invention seeks to solve is to provide electrolytes having high ionic conductivity, a mechanical structure stable, good thermal stability, long service life, and which do not pose any safety problems. Another problem that the present invention seeks to solve is to provide a method for manufacturing such a thin-film electrolyte that is simple, safe, fast, easy to implement, easy to industrialize and inexpensive. Another objective of the invention is to provide electrolytes for batteries capable of operating reliably and without risk of fire. Another problem is to provide an electrolyte that does not contain an organic binder, because such a binder can, in the event of an internal short circuit in the battery, cause and fuel a fire. Another object of the invention is to provide a battery with a rigid structure having a high power density capable of mechanically resisting shocks and vibrations. Another aim of the invention is to provide a method for manufacturing an electronic, electrical or electrotechnical device such as a battery, a capacitor, a supercapacitor comprising an electrolyte according to the invention. Another objective of the invention is to provide devices such as batteries, lithium ion battery cells, capacitors, supercapacitors having increased reliability and having a long service life and which can be encapsulated by coatings deposited by the atomic layer deposition (ALD) technique, at high temperature and under reduced pressure. Yet another aim of the invention is to propose devices such as batteries, lithium ion battery cells, capacitors, supercapacitors, capable of storing a high energy density, of restoring this energy with a very high power density (in particular in capacitors or supercapacitors), of withstanding high temperatures, of having a long lifespan and capable of being encapsulated by coatings deposited by ALD at high temperature and under reduced pressure. Objects of the invention According to the invention the problem is solved by the use of at least one thin-film electrolyte in an electrochemical device such as a lithium ion battery, said electrolyte comprising a porous inorganic layer having an interconnected network of open pores impregnated with a lithium ion-carrying phase. Preferably, the porous inorganic layer has a mesoporous structure whose porosity is greater than 25% by volume, preferably greater than 30% by volume. Advantageously, the open pores of said porous inorganic layer have an average diameter D50 of less than 100 nm, preferably less than 80 nm, preferably between 2 nm and 80 nm, and even more preferably between 2 nm and 50 nm, and a volume greater than 25% of the total volume of said thin-layer electrolyte, and preferably greater than 30%. Advantageously, the open pores of said porous inorganic layer have a volume of between 30% and 50% of the total volume of said thin-layer electrolyte. Preferably, said porous inorganic layer is free of organic binder. Advantageously, the thickness of the thin-layer electrolyte is less than 10 μm and preferably between 2.5 and 4.5 μm. Advantageously, said porous inorganic layer comprises an electronically insulating material, preferably chosen from AI2O3, SiO2, ZrO2, and / or a material selected from the group formed by: o garnets of formula Lid A1x A2y(TO4)z where ■ A1 represents a cation of oxidation state +II, preferably Ca, Mg, Sr, Ba, Fe, Mn, Zn, Y, Gd; and where ■ A2 represents a cation of oxidation state +III, preferably Al, Fe, Cr, Ga, Ti, La; and where ■ (TO4) represents an anion in which T is an atom with oxidation number +IV, located at the center of a tetrahedron formed by oxygen atoms, and in which TO4 advantageously represents the silicate or zirconate anion, knowing that all or part of the elements T with oxidation number +IV can be replaced by atoms with oxidation number +III or +V, such as Al, Fe, As, V, Nb, In, Ta; ■ knowing that: d is between 2 and 10, preferably between 3 and 9, and even more preferably between 4 and 8; x is between 2.6 and 3.4 (preferably between 2.8 and 3.2); y is between 1.7 and 2.3 (preferably between 1.9 and 2.1) and z is between 2.9 and 3.1; o garnets, preferably chosen from: Li7La3Zr20i2; Li6La2BaTa20i2; LissLasNbusIno^sO^; Li5La3M20i2 with M = Nb or Ta or a mixture of the two compounds; Li7.xBaxLa3.xM20i2 with 0 <x<1 et M = Nb ou Ta ou un mélange des deux composés ; le Li7.xLa3Zr2.xMxOi2 avec 0<x<2 et M = Al, Ga ou Ta ou un mélange de deux ou trois de ces composés ; o lithium phosphates, preferably chosen from: lithium phosphates of the NaSICON type, Li3PO4; LiPO3; Li3Alo,4Sc16(P04)3 called “LASP”; Li3(Sc2.xMx)(PO4)3 with M=Al or Y and 0 < x < 1; Lii+xMx(Sc)2.x(PO4)3 with M = Al, Y, Ga or a mixture of the three compounds and 0 < x < 0.8; Li1+xMx(Ga1. ySCy)2.x(PO4)3 with 0 < x < 0.8; 0 < y < 1 and M= Al or Y or a mixture of the two compounds; Li1+xMx(Ga)2.x(PO4)3 with M = Al, Y or a mixture of the two compounds and 0 < x < 0.8; Li1+xAlxTi2.x(PO4)3 with 0 < x < 1 called “LATP”; or Li1+xAlxGe2.x(PO4)3 with 0 < x < 1 called “LAGP”; or Li1+x+zMx(Ge1.yTiy)2.xSizP3.zOi2 with 0 <x<0,8 et 0<y<1,0 et 0<z<0,6 et M= Al, Ga ou Y ou un mélange de deux ou trois de ces composés ; le Li3+y(Sc2.xMx)QyP3. y012 avec M = Al et / ou Y et Q = Si et / ou Se, 0 < x < 0,8 et 0 < y < 1 ; ou le Li1+x+yMxSc2.xQyP3-yOi2 avec M = Al, Y, Ga ou un mélange des trois composés et Q = Si et / ou Se, 0 < x < 0,8 et 0 < y < 1 ; ou le Li1+x+y+zMx(Ga1.ySCy)2.xQzP3-zOi2 avec 0<x<0,8,0<y<1 , 0 < z < 0,6 avec M = Al ou Y ou un mélange des deux composés et Q= Si et / ou Se ; ou Lii+xM3xM2.xP30i2 with 0 < x < 1 and M3 = Cr and / or V, M = Sc, Sn, Zr, Hf, Se or Si, or a mixture of these compounds; . o lithium borates, preferably chosen from: Li3(Sc2.xMx)(BO3)3 with M=Al or Y and 0 < x < 1; Li1+xMx(Sc)2.x(BO3)3 with M = Al, Y, Ga or a mixture of the three compounds and 0 < x < 0.8; Li1+xMx(Ga1.ySCy)2.x(BO3)3 with 0 < x < 0.8, 0 < y < 1 and M= Al or Y; Li1+xMx(Ga)2.x(BO3)3 with M = Al, Y or a mixture of the two compounds and 0 < x < 0.8; U3BO3, Li3BO3-Li2SO4, Li3BO3-Li2SiO4, Li3BO3-Li2SiO4-Li2SO4; o oxynitrides, preferably chosen from Li3PO4.xN2x / 3, Li4SiO4.xN2x / 3, Li4GeO4.xN2x / 3 with 0 < x < 4 or U3BO3.XN2X / 3 with 0 < x < 3; o lithium compounds based on lithium and phosphorus oxynitride, called "LiPON", in the form of LixPOyNz with x ~2.8 and 2y+3z ~7.8 and 0.16 < z < 0.4, and in particular Li2.9PO3.3N0.46, but also the compounds LiwPOxNySz with 2x+3y+2z = 5 = w or the compounds LiwPOxNySz with 3.2 < x < 3.8, 0.13 < y < 0.4, 0 < z < 0.2, 2.9 < w < 3.3 or the compounds in the form of LitPxAlyOuNvSw with 5x+3y=5, 2u+3v+2w=5+t, 2.9 <t<3,3, 0,84<x<0,94, 0.094 <y<0,26, 3,2<u<3,8, 0,13<v<0,46, 0<w<0,2 ; o materials based on lithium phosphorus or boron oxynitrides, called respectively “LiPON” and “LIBON”, which may also contain silicon, sulfur, zirconium, aluminum, or a combination of aluminum, boron, sulfur and / or silicon, and boron for materials based on lithium phosphorus oxynitrides; o lithium compounds based on lithium, phosphorus and silicon oxynitride called “LiSiPON”, and in particular Lir9Sio.28P1.oO1.1Nro; o lithium oxynitrides of the types LiBON, LiBSO, LiSiPON, LiSON, thio-LiSiCON, LiPONB (where B, P and S represent boron, phosphorus and sulfur respectively); o lithium oxynitrides of LiBSO type such as (1-x)LiBO2- xLi2SO4 with 0.4 < x < 0.8; o lithiated oxides, preferably chosen from Li7La3Zr20i2 or Li5+xLa3(Zrx,A2.x)Oi2 with A=Sc, Y, Al, Ga and 1.4 < x < 2 or Li0.35La0.55TiO3 or Li3xLa2 / 3.xTiO3 with 0 < x < 0.16 (LLTO); o silicates, preferably chosen from Li2Si2O5, Li2SiO3, Li2Si2O6, LiAISiO4, Li4SiO4, LiAISi2Oe; o solid electrolytes of anti-perovskite type chosen from: Li3OA with A a halide or a mixture of halides, preferably at least one of the elements chosen from F, Cl, Br, I or a mixture of two or three or four of these elements; Li(3.^Mx / 2OA with 0 < x < 3, M a divalent metal, preferably at least one of the elements selected from Mg, Ca, Ba, Sr or a mixture of two or three or four of these elements, A a halide or a mixture of halides, preferably at least one of the elements selected from F, Cl, Br, I or a mixture of two or three or four of these elements; Li^M^OA with 0 < x < 3, M3 a trivalent metal, A a halide or a mixture of halides, preferably at least one of the elements selected from F, Cl, Br, I or a mixture of two or three or four of these elements; or LiCOXzY(1.z), with X and Y halides as mentioned above in relation to A, and 0 < z < 1, o the compounds La0,siLi0,34Ti2,94, Li3,4V0,4Ge0,6O4, Li2O-Nb2O5, LiAIGaSPO4; o formulations based on Li2CO3, B2O3, Li2O, AI(PO3)3LiF, P2S3, Li2S, Li3N, Li14Zn(GeO4)4, Li3i6Geo,6Vo,404, LiTi2(PO4)3, Li325Geo,25Po,25S4, Lii,3AI0,3Ti1i7(PO4)3, Li1+XAIXM2.X(PO4)3 (where M = Ge, Ti, and / or Hf, and where 0 < x < 1), LÎHx+yAIxTi^xSiyPs-yO^ (where 0 <x<1 etO<y<1). Advantageously, said pores of the thin-layer electrolyte are impregnated with a lithium ion-carrying phase, such as an organic solvent or a mixture of solvents in which at least one lithium salt is dissolved, and / or a polymer containing at least one lithium salt, and / or an ionic liquid or a mixture of ionic liquids, possibly diluted with a suitable solvent, containing at least one lithium salt. Said porous inorganic layer may be made of electrolyte material (or may comprise such material), i.e., a material within which lithium ions have sufficient mobility. Said porous inorganic layer may be consisting of a material (or may include such a material) which has neither sufficient electronic conductivity nor sufficient ionic conductivity for lithium ions. In both cases the electrolyte layer is formed by said porous inorganic layer and by said lithium ion-carrying phase with which it has been impregnated. In the second case it is this lithium ion-carrying phase alone which ensures the ionic conductivity in the electrolyte, whereas in the first case the mobility of the lithium ions within the material of the porous inorganic layer contributes to the ionic conductivity. Said lithium ion-carrying phase must comprise lithium ions. To form this carrier phase, the lithium ions may be dissolved in any suitable solvent. For example, said lithium ion-carrying phase may comprise an ionic liquid, possibly diluted with a suitable solvent. It may also comprise a polymer, which may be dissolved with a suitable solvent, which may be liquid or at least sufficiently viscous to be able to invade the open porosity of the porous inorganic layer. According to the invention, said porous inorganic layer is deposited by electrophoresis from a colloidal suspension of nanoparticles of an electronically insulating material or a solid electrolyte material. Preferably, it does not contain a binder. According to an essential characteristic of the invention, this suspension comprises aggregates of primary nanoparticles. Said primary nanoparticles forming the aggregates are preferably monodisperse, that is to say their primary diameter has a narrow distribution. This allows better control of porosity, and a fortiori of mesoporosity. The heat treatment leads to the partial coalescence of the material nanoparticles (a phenomenon called "necking"), knowing that the nanoparticles have a high surface energy which is the driving force for this structural modification; the latter occurs at a temperature well below the melting point of the material, and after a fairly short treatment time. This creates a three-dimensional mesoporous structure with an interconnected network of open pores, monobloc, free of binder, within which the lithium ions have a mobility that is not slowed down by grain boundaries or binder layers. This structure also gives good mechanical strength to the layer even without binder. Aggregates can also be obtained directly after hydrothermal synthesis if the suspension is not sufficiently purified: the ionic strength of the suspension then leads to the aggregation of the primary nanoparticles to form larger aggregated particles. A second subject of the invention is a method for manufacturing a thin-layer electrolyte deposited on an electrode, said layer preferably being free of organic binder and preferably having a porosity, preferably mesoporous, greater than 30% by volume, and even more preferably between 30% and 50% by volume, and said layer having pores with an average diameter D50 of less than 100 nm, preferably less than 80 nm and preferably less than 50 nm, said method being characterized in that: (a) a colloidal suspension comprising aggregates of nanoparticles of at least one inorganic material is supplied, said aggregates having an average diameter of between 80 nm and 300 nm (preferably between 100 nm and 200 nm), (b) an electrode is supplied, (c) a porous inorganic layer is deposited on said electrode by electrophoresis or by dip-coating, from a suspension of particles of inorganic material obtained in step (a); (d) drying said porous inorganic layer, preferably under an air flow to obtain a porous inorganic layer; (e) said porous inorganic layer is treated by mechanical compression and / or heat treatment, (f) said porous inorganic layer obtained in step (e) is impregnated with a phase carrying lithium ions. Another subject of the invention is a method for manufacturing a thin-layer electrolyte deposited on an electrode, said layer preferably being free of organic binder and preferably having a porosity, preferably mesoporous, greater than 30% by volume, and even more preferably between 30% and 50% by volume, and said layer having pores with an average diameter D50 of less than 100 nm, preferably less than 80 nm, preferably less than 50 nm, said method being characterized in that: (a1) a colloidal suspension comprising nanoparticles of at least one inorganic material P with an average primary diameter D50 less than or equal to 50 nm is supplied; (a2) the nanoparticles present in said colloidal suspension are destabilized so as to form aggregates of particles with an average diameter of between 80 nm and 300 nm, preferably between 100 nm and 200 nm, said destabilization preferably being carried out by adding a destabilizing agent such as a salt, preferably LiOH; (b) an electrode is supplied; (c) depositing on said electrode a porous inorganic layer by electrophoresis or by dip-coating, from said colloidal suspension comprising the aggregates of particles of at least one inorganic material obtained in step (a2); (d) drying the porous inorganic layer, preferably under an air flow to obtain a porous inorganic layer; (e) said porous inorganic layer is treated by mechanical compression and / or heat treatment, (f) said porous inorganic layer obtained in step (e) is impregnated with a phase carrying lithium ions. Advantageously, the porous inorganic layer obtained in step (c) has a thickness of less than 10 μm, preferably less than 8 μm, and even more preferably between 1 μm and 6 μm. Advantageously, the porous inorganic layer obtained in step (d) has a thickness of less than 10 μm, preferably between 2.5 μm and 4.5 μm. Advantageously, the primary diameter of said nanoparticles is between 10 nm and 50 nm, preferably between 10 nm and 30 nm. Preferably, the average diameter of the pores is between 2 nm and 50 nm, preferably between 6 nm and 30 nm and even more preferably between 8 nm and 20 nm. The electrode is a dense electrode or a porous electrode, preferably a mesoporous electrode. The method according to the invention can be used for the manufacture of thin-film electrolytes in electronic, electrical or electrotechnical devices, and preferably in devices selected from the group formed by: batteries, capacitors, supercapacitors, capacitors, resistors, inductors, transistors, photovoltaic cells. Another subject of the invention is a method of manufacturing a thin-film battery according to the invention, and comprising the steps of: -1- supply of at least two conductive substrates, previously covered with a layer of a material which can serve as an anode and respectively as a cathode (“anode layer” respectively “cathode layer”), -2- supply of a colloidal suspension comprising aggregates of nanoparticles of at least one inorganic material, said aggregates having an average diameter of between 80 nm and 300 nm (preferably between 100 nm and 200 nm), -3- Deposition of a porous inorganic layer by electrophoresis or by dip-coating, from a suspension of aggregated particles of inorganic material obtained in step -2- on the cathode or anode layer obtained in step -1-, -4- Drying of the layer thus obtained in step -3-, preferably under a flow of air, -5- Stacking of cathode and anode layers laterally offset, -6- Treatment of the stack of anode and cathode layers obtained in step -5- by mechanical compression and / or heat treatment so as to juxtapose the porous inorganic layers present on the anode and cathode layers, -7- Impregnation of the structure obtained in step -6- with a phase carrying lithium ions leading to the production of a battery. Advantageously, the cathode is a dense electrode or a porous electrode or, preferably, a mesoporous electrode. Advantageously, the anode is a dense electrode or a porous electrode or, preferably, a mesoporous electrode. Advantageously, the dense electrode or the porous electrode or the mesoporous electrode is coated, preferably by ALD, with a layer of an electronically insulating material, preferably ionically conductive.Advantageously, the cathode is a dense electrode or a dense electrode coated by ALD with an electronically insulating layer, preferably an electronically insulating and ionically conductive layer, or a porous electrode or a porous electrode coated by ALD with an electronically insulating layer, preferably an electronically insulating and ionically conductive layer or, preferably, a mesoporous electrode, or a mesoporous electrode coated by ALD with an electronically insulating layer, preferably a layer electronically insulating and ionically conductive and / or wherein the anode is a dense electrode or a dense electrode coated by ALD with an electronically insulating layer, preferably an electronically insulating and ionically conductive layer, or a porous electrode or a porous electrode coated by ALD with an electronically insulating layer, preferably an electronically insulating and ionically conductive layer or, preferably, a mesoporous electrode or a mesoporous electrode coated by ALD with an electronically insulating layer, preferably an electronically insulating and ionically conductive layer. Advantageously, when the cathode and / or the anode is a porous or mesoporous electrode, the impregnation of the structure (i.e. stack treated by mechanical compression and / or heat treatment) with a phase carrying lithium ions in step 7 allows the impregnation of the porous inorganic layer and of said cathode and / or of said anode. Advantageously, after step -7-: we successively place, alternately, on the battery: ■ at least a first layer of parylene and / or polyimide on said battery, ■ at least one second layer composed of an electrically insulating material by ALD (Atomic Layer Deposition) on said first layer of parylene and / or polyimide, ■ and on the alternating succession of at least a first and at least a second layer is deposited a layer making it possible to protect the battery against mechanical damage to the battery, preferably made of silicone, epoxy resin or parylene, or polyimide, thus forming a battery encapsulation system, the battery thus encapsulated is cut along two cutting planes to expose on each of the cutting planes the anode and cathode connections of the battery, so that the encapsulation system covers four of the six faces of said battery, preferably continuously, we successively deposit, on and around, these anodic and cathodic connections: ■ a first electronically conductive layer, preferably metallic, optional, preferably deposited by ALD, ■ a second layer based on silver-filled epoxy resin, deposited on the first electronically conductive layer, and ■ a third nickel-based layer, deposited on the second layer, and ■ a fourth layer based on tin or copper, deposited on the third layer. Advantageously, the anode and cathode connections are on opposite sides of the stack. Another subject of the invention relates to a battery comprising at least one thin-film electrolyte according to the invention. Another subject of the invention relates to a supercapacitor comprising at least one thin-film electrolyte according to the invention. Brief description of the figures Figures 1 and 2 illustrate different aspects of embodiments of the invention, without limiting its scope. Figure 1 illustrates nanoparticles before (Figure 1(a)) and after (Figure 1(b)) heat treatment, illustrating the phenomenon of “necking”. Figure 2(a) shows a diffractogram, Figure 2(b) a snapshot obtained by transmission electron microscopy of primary nanoparticles used for the deposition of the electrodes according to the invention by electrophoresis. Detailed description 1. Definitions For the purposes of this document, the size of a particle is defined by its largest dimension. 'Nanoparticle' means any particle or object of nanometric size with at least one of its dimensions less than or equal to 100 nm. For the purposes of this document, an electronically insulating material or layer, preferably an electronically insulating and ionically conductive layer, is a material or layer whose electrical resistivity (resistance to the passage of electrons) is greater than 105 Q-cm. By "mesoporous" materials, we mean any solid which has within its structure pores called "mesopores" having a size intermediate between that of micropores (width less than 2 nm) and that of macropores (width greater than 50 nm), namely a size between 2 nm and 50 nm. This terminology corresponds to that adopted by IIIPAC (International Union for Pure and Applied Chemistry), which is a reference for those skilled in the art. The term "nanopore" is therefore not used here, even if the mesopores as defined above have nanometric dimensions within the meaning of the definition of nanoparticles, knowing that pores smaller than mesopores are called "micropores" by those skilled in the art. A presentation of the concepts of porosity (and the terminology just explained above) is given in the article “Texture of powdery or porous materials” by F. Rouquerol et al. published in the collection “Techniques de l'Ingénieur”, treatise Analysis and Characterization, booklet P 1050; this article also describes the techniques for characterizing porosity, in particular the BET method. For the purposes of the present invention, the term "mesoporous layer" means a layer which has mesopores. As will be explained below, in these layers, the mesopores contribute significantly to the total pore volume; this fact is translated by the expression "Mesoporous layer with mesoporous porosity greater than X% by volume" used in the description below where X% is preferably greater than 25%, preferably greater than 30% and even more preferably between 30 and 50% of the total volume of the layer. The term "aggregate" means, according to the IUPAC definitions, a loosely bound assembly of primary particles. In this case, these primary particles are nanoparticles having a diameter that can be determined by transmission electron microscopy. An aggregate of aggregated primary nanoparticles can normally be destroyed (i.e. reduced to primary nanoparticles) in suspension in a liquid phase under the effect of ultrasound, according to a technique known to those skilled in the art. For the purposes of the present invention, the term "electrolyte layer" refers to the layer within an electrochemical device, this device being capable of operating according to its intended purpose. For example, in the case where said electrochemical device is a lithium ion secondary battery, the term "electrolyte layer" designates the "porous inorganic layer" impregnated with a phase carrying lithium ions. Said porous inorganic layer in an electrochemical device is also called a “separator” here, according to the terminology used by those skilled in the art. 2. Preparation of suspensions for electrophoretic deposition The method according to the invention uses electrophoresis or dip-coating of nanoparticle suspensions as a technique for depositing porous, preferably mesoporous, layers. In the context of the present invention, it is preferable not to prepare these nanoparticle suspensions from dry nanopowders. They can be prepared by grinding powders or nanopowders in the liquid phase. For example, particles can be wet-milled in ethanol; the particles can be milled with zirconia balls (e.g., 0.3 mm diameter) for a few hours (e.g., 5 hours) until a primary particle size greater than or equal to 50 nm, preferably greater than 80 nm, more preferably between 50 nm and 150 nm is obtained; this avoids uncontrolled sintering of the deposited layer, which could lead to the formation of dense layers. The conductivity of the suspension remains low, of the order of 20 pS / cm. This produces a size distribution that is unimodal, but can be quite broad. The disadvantage of nanomilling is the partial amorphization of the particle in an area close to the surface; this can hinder the processing of layers deposited from these nanoparticles. In another embodiment of the invention, the nanoparticles are prepared in suspension directly by precipitation. The synthesis of nanoparticles by precipitation makes it possible to obtain primary nanoparticles of very homogeneous size with a unimodal size distribution, good crystallinity and purity. In an even more preferred embodiment of the invention, the nanoparticles are prepared directly to their primary size by solvothermal or hydrothermal synthesis; this technique makes it possible to obtain nanoparticles with a unimodal and very narrow size distribution; these particles are called herein "monodisperse nanoparticles". Furthermore, these particles have very good crystallinity. The size of these non-aggregated particles is called their primary size.In the present invention it is preferably less than 100 nm, advantageously between 10 nm and 50 nm, preferably between 10 nm and 30 nm; this promotes during the subsequent process steps the formation of a porous, preferably mesoporous, interconnected network, thanks to the “necking” phenomenon. This suspension of monodisperse nanoparticles can be purified to remove any potentially interfering ions present in the liquid phase. Depending on the degree of purification, it can then be specially treated to form aggregates of a controlled size. More precisely, the formation of aggregates results from the destabilization of the suspension caused by ions. If the suspension has been completely purified it is stable, and ions are added to destabilize it, typically in the form of a salt; these ions are preferably lithium ions (preferably added in the form of LiOH). If the suspension has not been completely purified, the formation of aggregates can occur spontaneously or through aging. This method is simpler because it involves fewer purification steps, but it is more difficult to control the size of the aggregates. One of the essential aspects for the manufacture of porous layers according to the invention consists of controlling the size of the primary particles used and their degree of aggregation. It is this suspension of nanoparticle aggregates which is then used to deposit by electrophoresis the porous layers according to the invention. In one embodiment, the material used for the manufacture of porous layers according to the invention is chosen from inorganic materials with a low melting point, electronic insulators and stable in contact with the electrodes during the hot pressing steps. The more refractory the materials, the more it will be necessary to heat at high temperatures, thus risking modifying the interfaces with the electrode materials, in particular by interdiffusion, which causes parasitic reactions and creates depletion layers whose electrochemical properties differ from those found in the same material at a greater depth from the interface. The material used for the manufacture of porous layers according to the invention is inorganic. In a particular embodiment, the material used for the manufacture of porous inorganic layers according to the invention is an electronically insulating material. It may preferably be chosen from rAI2O3, SiO2, ZrO2. Alternatively, the material used for the manufacture of porous inorganic layers according to the invention may be an ionically conductive material such as a solid electrolyte. According to the invention, the solid electrolyte material used for the manufacture of a porous inorganic layer can be chosen in particular from: o garnets of formula Lid A1x A2y(TO4)z where ■ A1 represents a cation of oxidation state +II, preferably Ca, Mg, Sr, Ba, Fe, Mn, Zn, Y, Gd; and where ■ A2 represents a cation of oxidation state +III, preferably Al, Fe, Cr, Ga, Ti, La; and where ■ (TO4) represents an anion in which T is an atom with oxidation number +IV, located at the center of a tetrahedron formed by oxygen atoms, and in which TO4 advantageously represents the silicate or zirconate anion, knowing that all or part of the elements T with oxidation number +IV can be replaced by atoms with oxidation number +III or +V, such as Al, Fe, As, V, Nb, In, Ta; ■ knowing that: d is between 2 and 10, preferably between 3 and 9, and even more preferably between 4 and 8; x is between 2.6 and 3.4 (preferably between 2.8 and 3.2); y is between 1.7 and 2.3 (preferably between 1.9 and 2.1) and z is between 2.9 and 3.1; o garnets, preferably chosen from: Li7La3Zr20i2; Li6La2BaTa20i2; LissLasNbusIno^sO^; Li5La3M20i2 with M = Nb or Ta or a mixture of the two compounds; Li7.xBaxLa3.xM20i2 with 0 <x<1 et M = Nb ou Ta ou un mélange des deux composés ; le Li7.xLa3Zr2.xMxOi2 avec 0<x<2 et M = Al, Ga ou Ta ou un mélange de deux ou trois de ces composés ; o lithium phosphates, preferably chosen from: lithium phosphates of the NaSICON type, Li3PO4; LiPO3; Li3Alo,4Sc16(P04)3 called “LASP”; Li3(Sc2.xMx)(PO4)3 with M=Al or Y and 0 < x < 1; Li1+xMx(Sc)2.x(PO4)3 with M = Al, Y, Ga or a mixture of the three compounds and 0 < x < 0.8; Li1+xMx(Ga1.ySCy)2.x(PO4)3 with 0 < x < 0.8; 0 < y < 1 and M= Al or Y or a mixture of the two compounds; Li1+xMx(Ga)2.x(PO4)3 with M = Al, Y or a mixture of the two compounds and 0 < x < 0.8; Li1+xAlxTi2.x(PO4)3 with 0 < x < 1 called “LATP”; or Li1+xAlxGe2.x(PO4)3 with 0 < x < 1 called “LAGP”; or Li1+x+zMx(Ge1.yTiy)2.xSizP3.zOi2 with 0 <x<0,8 et 0<y<1,0 et 0<z<0,6 et M= Al, Ga ou Y ou un mélange de deux ou trois de ces composés ; le Li3+y(Sc2.xMx)QyP3.yOi2 avec M = Al et / ou Y et Q = Si et / ou Se, 0 < x < 0,8 et 0 < y < 1 ; ou le Li1+x+yMxSc2.xQyP3.yOi2 avec M = Al, Y, Ga ou un mélange des trois composés et Q = Si et / ou Se, 0 < x < 0,8 et 0 < y < 1 ; ou le Li1+x+y+zMx(Ga1.ySCy)2.xQzP3-zOi2 with 0 <x<0,8,0<y<1 , 0 < z < 0,6 avec M = Al ou Y ou un mélange des deux composés et Q= Si et / ou Se ; ou Li1+XM3XM2. xP30i2 avec 0 < x < 1 et M3= Cr et / ou V, M = Sc, Sn, Zr, Hf, Se ou Si, ou un mélange de ces composés ; . o lithium borates, preferably chosen from: Li3(Sc2.xMx)(BO3)3 with M=Al or Y and 0 < x < 1; Li1+xMx(Sc)2.x(BO3)3 with M = Al, Y, Ga or a mixture of the three compounds and 0 < x < 0.8; Li1+xMx(Ga1.ySCy)2.x(BO3)3 with 0 <x<0,8,0<y<1 et M= Al ou Y ; le Li1+xMx(Ga)2.x(BO3)3 avec M = Al, Y ou un mélange des deux composés et 0 < x < 0,8 ; le Li3BO3, le Li3BO3-Li2SO4, le Li3BO3-Li2SiO4, le Li3BO3-Li2SiO4-Li2SO4 ; o oxynitrides, preferably chosen from Li3PO4.xN2x / 3, Li4SiO4.xN2x / 3, Li4GeO4.xN2x / 3 with 0 < x < 4 or Li3BO3.xN2x / 3 with 0 < x < 3; o lithium compounds based on lithium and phosphorus oxynitride, called "LiPON", in the form of LixPOyNz with x ~2.8 and 2y+3z ~7.8 and 0.16 < z < 0.4, and in particular Li2.9PO3.3N0.46, but also the compounds LiwPOxNySz with 2x+3y+2z = 5 = w or the compounds LiwPOxNySz with 3.2 < x < 3.8, 0.13 < y < 0.4, 0 < z < 0.2, 2.9 < w < 3.3 or the compounds in the form of LitPxAlyOuNvSw with 5x+3y=5, 2u+3v+2w=5+t, 2.9 <t<3,3, 0,84<x<0,94, 0,094<y<0,26, 3,2<u<3,8, 0.13 <v<0,46, 0<w<0,2 ; o materials based on lithium phosphorus or boron oxynitrides, called respectively “LiPON” and “LIBON”, which may also contain silicon, sulfur, zirconium, aluminum, or a combination of aluminum, boron, sulfur and / or silicon, and boron for materials based on lithium phosphorus oxynitrides; o lithium compounds based on lithium, phosphorus and silicon oxynitride called “LiSiPON”, and in particular Lir9Sio.28P1.oO1.1Nro; o lithium oxynitrides of the types LiBON, LiBSO, LiSiPON, LiSON, thio-LiSiCON, LiPONB (where B, P and S represent boron, phosphorus and sulfur respectively); o lithium oxynitrides of LiBSO type such as (1-x)LiBO2- xLi2SO4 with 0.4 < x < 0.8; o lithiated oxides, preferably chosen from Li7La3Zr20i2 or Li5+xLa3(Zrx,A2.x)Oi2 with A=Sc, Y, Al, Ga and 1.4 < x < 2 or Li0.35La0.55TiO3 or Li3xLa2 / 3.xTiO3 with 0 < x < 0.16 (LLTO); o silicates, preferably chosen from Li2Si2O5, Li2SiO3, Li2Si2O6, LiAISiO4, Li4SiO4, LiAISi2Oe; o solid electrolytes of anti-perovskite type chosen from: Li3OA with A a halide or a mixture of halides, preferably at least one of the elements chosen from F, Cl, Br, I or a mixture of two or three or four of these elements; Li(3.X)Mx / 2OA with 0 < x < 3, M a divalent metal, preferably at least one of the elements chosen from Mg, Ca, Ba, Sr or a mixture of two or three or four of these elements, A a halide or a mixture of halides, preferably at least one of the elements chosen from F, Cl, Br, I or a mixture of two or three or four of these elements; Li(3.X)M3x / 3OA with 0 < x < 3, M3 a trivalent metal, A a halide or a mixture of halides, preferably at least one of the elements chosen from F, Cl, Br, I or a mixture of two or three or four of these elements; or LiCOXzY(iz), with X and Y halides as mentioned above in relation to A, and 0 < z < 1, o the compounds La0.5iLio.34Ti2.94, Li3.4Vo.4Geo.6O4, Li2O-Nb2O5, LiAIGaSPO4; o formulations based on Li2CO3, B2O3, Li2O, AI(PO3)3LiF, P2S3, Li2S, Li3N, Li14Zn(GeO4)4, Li3.6Geo.6Vo.4O4, LiTi2(PO4)3, Li3.25Geo.25Po,25S4, Li1.3AI0.3Ti1.7^04)3, Lii+XAIXM2.X(PO4)3 (where M = Ge, Ti, and / or Hf, and where 0 < x < 1), Li1+x+yAlxTi2.xSiyP3.yOi2 (where 0 <x<1 et 0<y<1). For the production of battery assemblies, the presence of a porous layer of solid electrolytes based on lithium phosphates between the anodes and cathodes is preferred. These materials have relatively low melting points, and the particles weld relatively well at moderate temperatures. Furthermore, the fact that they already contain inserted lithium prevents lithium from diffusing into the material during assembly, which could create depletion zones on the surface. According to the applicant's findings, with an average diameter of the nanoparticle aggregates of between 80 nm and 300 nm (preferably between 100 nm and 200 nm), a layer having open porosity is obtained during the subsequent process steps, with an average pore diameter of less than 100 nm, preferably less than 80 nm, preferably between 2 nm and 80 nm, and even more preferably between 2 nm and 50 nm. According to the invention, the porous inorganic layer can be deposited electrophoretically or by dip-coating. 3. Deposition of a porous inorganic layer by electrophoresis The method according to the invention can use electrophoresis of nanoparticle suspensions as a technique for depositing porous layers. The method for depositing layers from a suspension of nanoparticles is known as such (see for example EP 2 774 208 B1). The deposition by electrophoresis is carried out by applying an electric field between the substrate on which the deposition is carried out, and a counter-electrode, making it possible to set the charged particles of the colloidal suspension in motion, and to deposit them on the substrate. To ensure the stability of the colloidal suspension, polar nanoparticles are preferably used, and / or the colloidal suspension advantageously has a Zeta potential in absolute value greater than 25 mV. Electrophoretic deposition is carried out from a suspension of particles of inorganic material suitable for use as a porous inorganic layer according to the invention, on a substrate having sufficient electrical conductivity. Thus, it may be a metal substrate, for example a metal foil (such as a stainless steel foil with a thickness of about 5 μm), or a plastic foil provided with a conductive surface (for example coated with a layer of metal or a layer of a conductive oxide, such as an ITO layer, which has the advantage of also acting as a diffusion barrier). To manufacture a battery, the inorganic material can be deposited by electrophoresis on a layer of electrode material (anode or cathode). Said layer of electrode material may have been deposited, for example, on a conductive substrate such as a metal foil or a polymer foil coated with a conductive layer. For electrophoresis to take place, a counter electrode is placed in the suspension and a voltage is applied between the substrate and said counter electrode. The electrophoretic deposition rate depends on the applied electric field and the electrophoretic mobility of the suspension particles and can be very high. For an applied voltage of 200 V, the deposition rate can reach about 10 pm / min. The inventor found that this technique allows very homogeneous layers to be deposited over very large areas (provided that the particle concentrations and electric fields are homogeneous over the surface of the substrate). It lends itself equally well to a continuous strip process, as well as to a batch process on plates. The porous inorganic layer, preferably mesoporous, is deposited on an anode layer and / or a cathode layer themselves formed on a conductive substrate by a suitable method, and / or directly on a sufficiently conductive substrate. The deposition of a layer of material by electrophoresis allows perfect coverage of the surface of the electrode layer regardless of its geometry and the presence of asperity defects. It therefore guarantees the dielectric properties of the layer. In an advantageous embodiment, high-frequency current pulses are applied, as this prevents the formation of bubbles on the surface of the electrodes and variations in the electric field in the suspension during deposition. The thickness of the porous inorganic layer thus deposited is advantageously less than 10 μm, preferably less than 8 μm, and is even more preferably between 1 μm and 6 μm. The compactness of the layer obtained by electrophoretic deposition, and the absence of organic compounds in large quantities in the layer makes it possible to limit or even avoid the risks of cracks or the appearance of other defects in the layer during the drying steps. According to an essential characteristic of the present invention, the porous inorganic layer according to the invention does not contain an organic binder. 4. Deposition of a porous inorganic layer by dip-coating Nanoparticles of an inorganic material can be deposited by the dip-coating process, regardless of the chemical nature of the nanoparticles used. This deposition process is preferred when the inorganic nanoparticles have little or no electrical charge. In order to obtain a layer of a desired thickness, the step of depositing the inorganic nanoparticles by dip-coating followed by the step of drying the resulting layer are repeated as many times as necessary. Although this succession of dipping / drying coating steps is time-consuming, the dip-coating process is simple, safe, easy to implement and industrialize; it allows a homogeneous and compact final layer to be obtained. 5. Treatment and properties of deposited layers After deposition, the layers must be dried; drying must not cause cracks to form. For this reason, it is preferable to carry it out under controlled humidity and temperature conditions. The dried layers can be consolidated by a pressing and / or heat treatment step. In a very advantageous embodiment of the invention, this mechanical (i.e. mechanical compression) and / or thermal treatment leads to a partial coalescence of the primary nanoparticles in the aggregates, and between neighboring aggregates; this phenomenon is called “necking” or “neck formation”. It is characterized by the partial coalescence of two particles in contact, which remain separated but connected by a (narrowed) neck; this is illustrated schematically in Figure 1. Thus, a three-dimensional network of interconnected particles is formed; this network includes an open porosity formed by interconnected pores. The size of these pores is advantageously in the mesopore range, i.e. between 2 nm and 50 nm.Advantageously, the open pores of said porous inorganic layer have a volume greater than 25%, preferably greater than 30% of the total volume of said porous inorganic layer. When the volume of the pores of the porous inorganic layer is less than 25%, a three-dimensional network of interconnected particles cannot be obtained; the layer obtained in this case has a closed porosity which does not allow the structure to be subsequently impregnated with a phase carrying lithium ions. The temperature required to obtain “necking” depends on the material; given the diffusive nature of the phenomenon which leads to necking, the duration of the treatment depends on the temperature. Depending on the case, this heat treatment, if carried out at a sufficient temperature, for example 350°C, also makes it possible to eliminate any organic residues from the manufacturing process of the suspension of nanoparticles or solvents. Heat treatment and / or pressing is advantageously carried out during subsequent manufacturing steps serving other purposes; this is described in section 6 below in relation to battery manufacturing. 6. Assembling a battery One of the aims of the invention is to provide new thin-film electrolytes for lithium-ion secondary batteries. Here we describe the production of a battery with an electrolyte comprising a porous inorganic layer. A suspension of nanoparticles of precursor material of a porous inorganic layer can be prepared by solvothermal, in particular hydrothermal, route, which leads directly to nanoparticles of good crystallinity. The porous inorganic layer is deposited by electrophoresis or by dip-coating on a cathode layer covering a substrate and / or on an anode layer covering a substrate; in both cases, said substrate must have sufficient conductivity to be able to act as a cathode or anode current collector, respectively. The assembly of the cell formed by an anode layer, the porous inorganic layer and a cathode layer is carried out by hot pressing, preferably under an inert atmosphere. The temperature is advantageously between 300 °C and 500 °C, preferably between 350 °C and 450 °C. The pressure is advantageously between 40 MPa and 100 MPa. The hot pressing can be carried out for example at 350 °C and 100 MPa. Then, this cell, which is completely solid and rigid, and which does not contain any organic material, is impregnated by immersion in a lithium ion carrier phase. Due to the open porosity and the small size of the porosity (especially when the D50 size of the pores is less than 50 nm), the impregnation in the whole cell (electrodes and separator) is done by capillarity. A particularly preferred separator is a Li3Alo,4Sc1,6(P04)3 separator with mesoporosity. Details on the impregnation are given in section 7 below. The lithium ion carrier phase may contain, for example, LiPF6 or LiBF4 dissolved in an aprotic solvent, or an ionic liquid containing lithium salts. Ionic liquids, optionally dissolved in a suitable solvent, and / or mixed with organic electrolytes, may also be used. For example, LiPF6 dissolved in EC / DMC may be mixed at 50% by mass with an ionic liquid containing lithium salts of the LiTFSI:PYR14TFSI type (molar ratio 1:9). Ionic liquid mixtures that can operate at low temperatures, such as the LiTFSI:PYR13FSI:PYR14TFSI mixture (molar ratio 2:9:9), may also be produced. EC is the common abbreviation for ethylene carbonate (CAS No. 96-49-1). DMC is the common abbreviation for dimethyl carbonate (CAS No. 616-38-6). LITFSI is the common abbreviation for lithium bis-trifluoromethanesulfonimide (CAS No. 90076-65-6). PYR13FSI is the common abbreviation for N-Propyl-N-Methylpyrrolidinium bis(fluorosulfonyl)imide. PYR14TFSI is the common abbreviation for 1-butyl-1-methylpyrrolidinium bis(trifluoro-methanesulfonyl)imide. Here we describe another example of manufacturing a lithium ion battery according to the invention. This method comprises the steps of: (1) Provision of at least two conductive substrates previously covered with a layer of a material capable of serving as an anode and, respectively, as a cathode (these layers being called “anode layer” and “cathode layer”), (2) Supply of a colloidal suspension comprising aggregates of nanoparticles of at least one inorganic material, said aggregates having an average diameter D50 of between 80 nm and 300 nm (preferably between 100 nm and 200 nm), (3) Deposition of a porous inorganic layer by electrophoresis or by dip-coating, from said colloidal suspension on at least one cathode or anode layer obtained in step (1), (4) Drying the layer thus obtained, preferably under a flow of air, (5) Stacking of laterally offset cathode and anode layers, (6) Treatment of the stack of anode and cathode layers obtained in step (5) by mechanical compression and / or heat treatment so as to juxtapose the porous inorganic layers present on the anode and cathode layers, (7) Impregnation of the structure obtained in step (6) with an electrolytic solution such as an ionic liquid comprising a lithium salt, to obtain a battery. The average primary diameter D50 of the nanoparticles forming the aggregates of said suspension may be less than or equal to 50 nm, and in this case this suspension is preferably prepared by precipitation or by solvothermal synthesis. It may also be greater than 50 nm, preferably between 50 nm and 150 nm and in this case suspensions obtained by wet grinding may be used. Advantageously, the anode and cathode layers may be dense electrodes, i.e. electrodes having a volume porosity of less than 20%, porous electrodes, preferably having an interconnected network of open pores or mesoporous electrodes, preferably having an interconnected network of open mesopores. Due to the very large specific surface area of ​​the porous, preferably mesoporous, electrodes, when used with a liquid electrolyte, parasitic reactions may occur between the electrodes and the electrolyte; these reactions are at least partially irreversible. In an advantageous embodiment, a very thin layer of an electronically insulating material, which is preferably ionically conductive, is applied to the porous, preferably mesoporous, electrode layer in order to block these parasitic reactions. In the context of dense electrodes and in another advantageous embodiment, a very thin layer of an electronically insulating material, which is preferably ionically conductive, is applied to the electrode layer in order to reduce the interfacial resistance existing between the dense electrode and the electrolyte. This layer of electronically insulating material, which is preferably ionically conductive, advantageously has an electronic conductivity of less than 10'8 S / cm. Advantageously, this deposition is carried out at least on one face of the electrode, whether porous or dense, which forms the interface between the electrode and the electrolyte. This layer can, for example, be made of alumina, silica, or zirconia. On the cathode, Li4Ti5Oi2 or another material can be used which, like Li4Ti50i2, has the characteristic of not inserting lithium at the operating voltages of the cathode and of behaving as an electronic insulator. Alternatively, this layer of an electronically insulating material can be an ionic conductor, which advantageously has an electronic conductivity of less than 10'8 S / cm. This material must be chosen so as not to insert lithium at the operating voltages of the battery, but only to transport it. For example, Li3PO4, Li3BO3, lithium lanthanum zirconium oxide (called "LLZO"), such as Li7La3Zr20i2, which have a wide range of operating potential, can be used for this purpose. On the other hand, lithium lanthanum titanium oxide (abbreviated "LLTO"), such as Li3xLa2 / 3_xTiO3, lithium aluminum titanium phosphate (abbreviated "LATP"), lithium aluminum germanium phosphate (abbreviated "LAGP"), can be used only in contact with the cathodes because their operating potential range is restricted; beyond this range they are likely to insert lithium into their crystallographic structure. This deposit further improves the performance of lithium ion batteries with at least one electrode, whether porous or dense. In the case of impregnated porous electrodes, this deposit reduces faradaic interface reactions with the electrolytes. These parasitic reactions are all the more significant as the temperature is high; they are the cause of reversible and / or irreversible capacity losses. In the case of dense electrodes in contact with the electrolyte, it also limits interface resistances linked to the appearance of space charges. Very advantageously, this deposition is carried out by a technique allowing a conformal coating (also called "conformal deposition"), i.e. a deposition which faithfully reproduces the atomic topography of the substrate on which it is applied. The ALD (Atomic Layer Deposition) technique, known as such, may be suitable. It can be implemented on dense electrodes before the deposition of the porous inorganic layer and before the assembly of the cell. It can be implemented on porous electrodes, preferably mesoporous, before and / or after the deposition of the porous inorganic layer and before the assembly of the cell. The ALD deposition technique is carried out layer by layer, by a cyclic process, and makes it possible to produce a conformal coating which faithfully reproduces the topography of the substrate; it covers the entire surface of the electrodes. This conformal coating typically has a thickness of between 1 nm and 5 nm. When the electrodes used are porous and covered with a nanolayer of an electronically insulating material, preferably ionically conductive, it is preferable that the primary diameter D50 of the particles of electrode material used to produce them is at least 10 nm in order to prevent the layer of electronically insulating material, preferably ionically conductive, from blocking the open porosity of the electrode layer. The layer of an electronically insulating material, preferably an ionic conductor, should only be deposited on electrodes that do not contain an organic binder. Indeed, ALD deposition is carried out at a temperature typically between 100 °C and 300 °C. At this temperature, the organic materials forming the binder (for example, the polymers contained in electrodes produced by ink tape casting) risk decomposing and will pollute the ALD reactor. Furthermore, the presence of residual polymers in contact with the particles of active electrode material can prevent the ALD coating from coating all of the particle surfaces, which reduces its effectiveness. For example, an alumina layer with a thickness of around 1.6 nm may be suitable. If the electrode is a cathode, it can be made from a cathode material P chosen from: the oxides LiMn2O4, LiCoO2, LiNiO2, LiMn^sNio.sO^ LiMn1,5Nio,5.xXx04 where X is selected from Al, Fe, Cr, Co, Rh, Nd, other rare earths such as Sc, Y, Lu, La, Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and where 0 < x < 0.1, LiMn2.xMxO4 with M = Er, Dy, Gd, Tb, Yb, Al, Y, Ni, Co, Ti, Sn, As, Mg or a mixture of these compounds and where 0 < x < 0.4, LiFeO2, LiMn1 / 3Ni1 / 3Co1 / 3O2, LiNio.8Co0.i5Alo.o502] phosphates LiFePO4, LiMnPO4, LiCoPO4, LiNiPO4, Li3V2(PO4)3; phosphates of formula LiMM'PO4, with M and M' (M # M') selected from Fe, Mn, Ni, Co, V; - all lithiated forms of the following chalcogenides: V2O5, V3O8, TiS2, titanium oxysulfides (TiOySz with z=2-y and 0.3 <y<1), les oxysulfures de tungstène (WOySz avec 0.6<y<3 et 0.1<z<2), CuS, CuS2, de préférence LixV2O5avec 0 <x<2, LixVsOs avec 0 < x < 1,7, LixTiS2 avec 0 < x < 1, les oxysulfures de titane et de lithium LixTiOySz avec z=2-y, 0,3<y<1, LixWOySz, LixCuS, LixCuS2. If the electrode is an anode, it can be made from an anode material P chosen from: lithium iron phosphate (typical formula LiFePO4); mixed silicon and tin oxynitrides (typical formula SiaSnbOyNz with a>0, b>0, a+b<2, 0 <y<4, 0<z<3) (appelés aussi SiTON), et en particulier le SiSno.87O1.2N! 72 ; ainsi que les oxynitrures-carbures de formule typique SiaSnbCcOyNz avec a> 0, b>0, a+b<2, 0 <c<10, 0<y<24, 0<z<17; nitrides of type SixNy (in particular with x=3 and y=4), SnxNy (in particular with x=3 and y=4), ZnxNy (in particular with x=3 and y=2), Li3.xMxN (with 0 <x<0,5 pour M=Co, 0<x<0,6 pour M=Ni, 0<x<0,3 pour M=Cu); Si3.xMxN4avec 0<x<3. the oxides SnO2, SnO, Li2SnO3, SnSiO3, LixSiOy (x>=0 and 2>y>0), Li4Ti50i2, SnBo,6Po,402,9 and TiO2. On dense, porous, preferably mesoporous electrodes, coated or not with a layer of an electronically insulating material, preferably ionically conductive by ALD, an electrolyte according to the invention can be produced. In order to obtain a battery with high energy density and high power density, this battery advantageously contains a porous, preferably mesoporous, anode layer and cathode layer, and an electrolyte according to the invention. Advantageously, the anode and cathode layers, coated or not with an ALD layer of an electronically insulating material, preferably ionically conductive, then covered with a porous inorganic layer, are hot-pressed to promote cell assembly without inducing sintering. The deposits remain porous and can be subsequently impregnated with an electrolytic solution, avoiding any risk of subsequent short circuiting. Advantageously, a battery comprising at least one porous electrode, preferably mesoporous, and an electrolyte according to the invention has increased performance, in particular a high power density. Below we describe an example of manufacturing a lithium ion battery according to the invention comprising at least one porous, preferably mesoporous, electrode. This method comprises the steps of: (1) Supply of a colloidal suspension comprising nanoparticles of at least one cathode material of primary diameter average D50 less than or equal to 50 nm; (2) Supply of a colloidal suspension comprising nanoparticles of at least one anode material with an average primary diameter D50 less than or equal to 50 nm; (3) Provision of at least two flat conductive substrates, preferably metallic, said conductive substrates being able to serve as current collectors of the battery, (4) Deposition of at least one thin layer of cathode, respectively anode, preferably by dip-coating or by electrophoresis, preferably by galvanostatic electrodeposition by pulsed currents, from said suspension of nanoparticles of material obtained in step (1), respectively in step (2), on said substrate obtained in step (3), (5) Drying of the layer thus obtained in step (4), (6) Optionally, deposition by ALD of a layer of an electronically insulating material on the surface of the cathode and / or anode layer obtained in step (5), (7) Deposition by electrophoresis or by dip-coating of a porous inorganic layer from a colloidal suspension comprising aggregates of nanoparticles of at least one inorganic material, on the cathode and / or anode layer obtained in step 5) or in step 6), to obtain a first and / or a second intermediate structure, (8) Drying the layer thus obtained in step (7), preferably under an air flow, (9) Production of a stack from said first and / or second intermediate structure to obtain a stack of the “substrate / anode / porous inorganic layer / cathode / substrate” type: • either by depositing an anode layer on said first intermediate structure, • either by depositing a cathode layer on said second intermediate structure, • either by superimposing said first intermediate structure and said second intermediate structure so that the two layers of porous inorganic layers are placed one on top of the other, (10) Hot pressing of the stack obtained in step (9), (11) Impregnation of the structure obtained in step (10) with a phase carrying lithium ions leading to the production of an impregnated structure, preferably a cell. Advantageously, said aggregates of nanoparticles of at least one inorganic material have an average diameter of between 80 nm and 300 nm, preferably between 100 nm and 200 nm. Once the assembly of a stack constituting a battery by hot pressing is complete, it can be impregnated with a lithium ion-carrying phase. This phase can be a solution formed by a lithium salt dissolved in an organic solvent or a mixture of organic solvents, and / or dissolved in a polymer containing at least one lithium salt, and / or dissolved in an ionic liquid (i.e. a molten lithium salt) containing at least one lithium salt. This phase can also be a solution formed from a mixture of these components. The porous, preferably mesoporous, electrodes are capable of absorbing a liquid phase by simple capillarity when the average diameter D50 of the pores is between 2 nm and 80 nm, preferably between 2 nm and 50 nm, preferably between 6 nm and 30 nm, preferably between 8 nm and 20 nm. This effect is completely unexpected and is particularly favored with the reduction in the pore diameter of these electrodes. Advantageously, the pores of the porous electrode, preferably mesoporous, are impregnated with an electrolyte, preferably a phase carrying lithium ions such as an ionic liquid containing lithium salts, possibly diluted in an organic solvent or a mixture of organic solvents containing a lithium salt which may be different from that dissolved in the ionic liquid. This results in a lithium ion battery cell with very high power density. 7. Impregnation of porous inorganic layers As indicated in the previous section, once the deposition of a porous inorganic layer and its treatment have been completed, for example during the assembly of a stack constituting a battery by hot pressing, it can be impregnated with a phase carrying lithium ions. This phase can be a solution formed by a lithium salt dissolved in an organic solvent or a mixture of organic solvents, and / or dissolved in a polymer containing at least one lithium salt, and / or dissolved in an ionic liquid (i.e. a molten lithium salt) containing at least one lithium salt. This phase can also be a solution formed from a mixture of these components. The inventors have found that the porous inorganic layers according to the invention are capable of absorbing a liquid phase by simple capillarity. This completely unexpected effect is specific to the deposits of porous inorganic layers according to the invention; it is particularly favored when the average diameter D50 of the mesopores is between 2 nm and 80 nm, preferably between 2 nm and 50 nm, preferably between 6 nm and 30 nm, and even more preferably between 8 nm and 20 nm. In an advantageous embodiment of the invention, the porous inorganic layer has a porosity, and preferably a mesoporous porosity, greater than 30%, pores with an average diameter D50 of less than 50 nm, and a primary particle diameter of less than 30 nm. Its thickness is advantageously less than 10 μm, and preferably between 2.5 μm and 4.5 μm, so as to reduce the final thickness of the battery without reducing its properties. It is free of binder. Its pores are impregnated with an electrolytic solution, such as an ionic liquid containing lithium salts, possibly diluted in an organic solvent or a mixture of organic solvents containing a lithium salt which may be different from that dissolved in the ionic liquid. In a particularly advantageous embodiment, the porosity, preferably mesoporous, is between 35% and 50%, and even more preferably between 40% and 50%. The liquid "nanoconfined" or "nanoprisoned" in the porosities, and in particular in the mesoporosities, can no longer escape. It is bound by a phenomenon called here "absorption in the mesoporous structure" (which does not seem to have been described in the literature in the context of lithium ion batteries) and it can no longer escape even when the cell is placed under vacuum. The battery is then considered quasi-solid. 8. Encapsulation The battery must then be encapsulated by a suitable method to ensure its protection from the atmosphere. The encapsulation system comprises at least one layer, and preferably represents a stack of several layers. If the encapsulation system is composed of a single layer, it must be deposited by ALD or be made of parylene and / or polyimide. These encapsulation layers must be chemically stable, resistant to high temperatures and impermeable to the atmosphere (barrier layer). One of the methods described in patent applications WO 2017 / 115 032, WO 2016 / 001584, WO2016 / 001588 or WO 2014 / 131997 can be used. Advantageously, the first layer is a polymeric layer, preferably based on parylene and / or polyimide. It can be deposited under vacuum, by a chemical vapor deposition (CVD) technique. This first encapsulation layer is advantageously obtained from the condensation of gaseous monomers deposited by chemical vapor deposition (CVD) on the surfaces, which makes it possible to have a conformal and uniform covering of all accessible surfaces of the object. It allows to follow the variations in volume of the battery during its operation and facilitates the clean cutting of the batteries due to its elastic properties. The thickness of this first encapsulation layer is between 2 pm and 10 pm, preferably between 2 pm and 5 pm and even more preferably around 3 pm. It allows to cover all accessible surfaces of the stack, to close all pores of these accessible surfaces and to standardize the chemical nature of the substrate. Encapsulation can thus be carried out directly on the stacks, the coating being able to penetrate into all available cavities. It is recalled here that thanks to the nanoconfinement of the conductive phase carrying lithium ions in the porosities of the electrolyte according to the invention and / or the electrodes, the battery can undergo vacuum treatments. In one embodiment, a first layer of parylene is deposited, such as a layer of parylene C, parylene D, a layer of parylene N (CAS No.: 1633-22-3) or a layer comprising a mixture of parylene C, D and / or N. Parylene (also called polyparaxylylene or poly(p-xylylene)) is a dielectric, transparent, semi-crystalline material which has high thermodynamic stability, excellent resistance to solvents and very low permeability. This layer of parylene protects the sensitive elements of the battery from their environment. This protection is increased when this first encapsulation layer is made from parylene N. In another embodiment, a first polyimide-based layer is deposited. This polyimide layer protects the sensitive elements of the battery from their environment. In another advantageous embodiment, the first encapsulation layer consists of a first layer of polyimide, preferably about 1 μm thick, on which is deposited a second layer of parylene, preferably about 2 μm thick. This protection is increased when this second layer of parylene, preferably about 2 μm thick, is made from parylene N. The polyimide layer associated with the parylene layer improves the protection of the sensitive elements of the battery from their environment. However, the inventors observed that this first layer, when it is based on parylene, does not have sufficient stability in the presence of oxygen. When this first layer is based on polyimide, it does not have sufficient sealing, particularly in the presence of water. For these reasons, a second layer is deposited which coats the first layer. Advantageously, a second layer composed of an electrically insulating material may be deposited by a conformal deposition technique, such as the deposition of atomic layer deposition (ALD) on the first layer. This results in conformal coverage of all accessible surfaces of the stack covered with a layer of parylene and / or polyimide; this second layer is preferably an inorganic layer. The growth of the layer deposited by ALD is influenced by the nature of the substrate. A layer deposited by ALD on a substrate with different areas of different chemical natures will have inhomogeneous growth, which may lead to a loss of integrity of this second protective layer. This second layer deposited on the first layer of parylene and / or polyimide protects the first layer of parylene and / or polyimide against air and improves the lifespan of the encapsulated battery. ALD deposition techniques are particularly well suited to covering surfaces with high roughness in a completely watertight and conformal manner. They allow the production of conformal layers, free from defects, such as holes (so-called "pinhole-free" layers) and represent very good barriers. Their WVTR coefficient is extremely low. The WVTR coefficient (water vapor transmission rate) is used to evaluate the water vapor permeance of the encapsulation system. The lower the WVTR coefficient, the more watertight the encapsulation system. For example, a 100 nm thick AI2O3 layer deposited by ALD has a water vapor permeation of 0.00034 g / m2.d. The second layer may be made of ceramic material, glassy material or glass-ceramic material, for example in the form of oxide, type AI2O3, nitride, phosphates, oxynitride, or siloxane.This second encapsulation layer has a thickness of less than 200 nm, preferably between 5 nm and 200 nm, more preferably between 10 nm and 100 nm and even more preferably of the order of fifty nanometers. This second layer deposited by ALD allows on the one hand to ensure the watertightness of the structure, i.e. to prevent the migration of water inside the structure and on the other hand to protect the first layer of parylene and / or polyimide from the atmosphere in order to avoid its degradation. However, these layers deposited by ALD are very mechanically fragile and require a rigid support surface to ensure their protective role. The deposition of a fragile layer on a flexible surface would lead to the formation of cracks, causing a loss of integrity of this protective layer. In one embodiment, a third encapsulation layer is deposited on the second encapsulation layer to increase the protection of the battery cells from their external environment. Typically, this third layer is made of polymer, e.g. example in silicone (deposited for example by impregnation or by plasma-assisted chemical vapor deposition from hexamethyldisiloxane (HMDSO, CAS No.: 107-46-0)), or in epoxy resin, or in parylene, or in polyimide. Further, the encapsulation system may comprise an alternating succession of parylene and / or polyimide layers, preferably about 3 μm thick, and layers composed of an electrically insulating material such as inorganic layers conformally deposited by ALD as previously described to create a multi-layer encapsulation system.In order to improve the performance of the encapsulation, the encapsulation system may advantageously comprise a first layer of parylene and / or polyimide, preferably about 3 μm thick, a second layer composed of an electrically insulating material, preferably an inorganic layer, conformally deposited by ALD on the first layer, a third layer of parylene and / or polyimide, preferably about 3 μm thick deposited on the second layer and a fourth layer composed of an electrically insulating material conformally deposited by ALD on the third layer. Advantageously, a final encapsulation layer is deposited on this alternating succession of parylene and / or polyimide layers, preferably about 3 μm thick, and inorganic layers conformally deposited by ALD, to increase the protection of the battery cells from their external environment and protect them against mechanical damage. This final encapsulation layer has a thickness of about 10-15 μm. Typically, this last layer is made of polymer, for example silicone (deposited for example by dipping or by plasma-enhanced chemical vapor deposition from hexamethyldisiloxane (HMDSO)), or epoxy resin, or parylene, or polyimide. For example, a silicone layer (typical thickness about 15 μm) can be deposited by injection to protect the battery against mechanical damage.These materials are resistant to high temperatures and the battery can therefore be easily assembled by soldering on electronic boards without the appearance of a glass transition. Advantageously, the encapsulation of the battery is carried out on four of the six faces of the stack. The encapsulation layers surround the periphery of the stack, the rest of the protection against the atmosphere being ensured by the layers obtained by the terminations. After the battery encapsulation step, terminations are added to establish the electrical contacts necessary for the battery to function properly. To make the terminations, the encapsulated stack is cut along sectional planes to obtain unitary battery components, with the anodic and cathodic connections of the battery being exposed on each of the sectional planes, so that the encapsulation system covers four of the six faces of said battery, preferably continuously, so that the system can be assembled without soldering, the other two faces of the battery being subsequently covered by the terminations. Preferably, the anodic connections and the cathodic connections are located on opposite sides of the stack. On and around these connections is deposited a termination system. The connections can be metallized using plasma deposition techniques known to those skilled in the art, preferably by ALD and / or by immersion in a conductive epoxy resin (loaded with silver) and / or a bath of molten tin.Preferably, the terminations consist of a stack of layers successively comprising a first thin electronically conductive covering layer, preferably metallic, deposited by ALD, a second layer of silver-filled epoxy resin deposited on the first layer and a third tin-based layer deposited on the second layer. The first conductive layer deposited by ALD serves to protect the battery section from moisture. This first conductive layer deposited by ALD is optional. It makes it possible to increase the calendar life of the battery by reducing the WVTR at the termination. This first thin covering layer may in particular be metallic or based on metal nitride. The second layer of silver-filled epoxy resin makes it possible to provide “flexibility” to the connector without breaking the electrical contact when the electrical circuit is subjected to thermal and / or vibration stresses.. The third layer of tin-based metallization is used to ensure the solderability of the battery. In another embodiment, this third layer can be composed of two layers of different materials. A first layer comes into contact with the silver-filled epoxy resin layer. This layer is made of nickel and is produced by electrolytic deposition. The nickel layer serves as a thermal barrier and protects the rest of the component from diffusion during the reflow assembly steps. The last layer, deposited on the nickel layer, is also a metallization layer, preferably made of tin to make the interface compatible with reflow assemblies. This tin layer can be deposited either by dipping in a molten tin bath or by electrodeposition; these techniques are known as such. For some assemblies on copper tracks by microwiring, it may be necessary to have a final layer of copper metallization. Such a layer can be achieved by electrodeposition instead of tin. In another embodiment, the terminations may be made up of a stack of layers successively comprising a layer of epoxy resin loaded with silver and a second layer based on tin or nickel deposited on the first layer. In another embodiment, the terminations may be made up of a stack of layers successively comprising a layer of epoxy resin loaded with silver, a second nickel-based layer deposited on the first layer and a third layer based on tin or copper. The terminals allow the electrical connections to be made alternately positive and negative on each end of the battery. These terminals allow the electrical connections to be made in parallel between the different battery elements. For this, only the cathode connections come out on one end, and the anode connections are available on the other ends. Examples Example 1: Production of a mesoporous electrolyte layer based on Li3PO4 deposited on a cathode layer a. Production of a suspension of Li3PO4 nanoparticles Two solutions were prepared: 11.44 g of CH3COOLi, 2H2O was dissolved in 112 ml of water, then 56 ml of water was added with vigorous stirring to the medium to obtain solution A. 4.0584g of H3PO4 were diluted in 105.6 ml of water, then 45.6 ml of ethanol were added to this solution to obtain a second solution hereinafter called solution B. Solution B was then added, with vigorous stirring, to solution A. The resulting solution, perfectly clear after the bubbles formed during mixing had disappeared, was added to 1.2 liters of acetone using an Ultraturrax™ homogenizer to homogenize the medium. A white precipitation suspended in the liquid phase was immediately observed. The reaction medium was homogenized for 5 minutes and then kept for 10 minutes under magnetic stirring. It was left to settle for 1 to 2 hours. The supernatant was discarded and the remaining suspension was centrifuged for 10 minutes at 6000 rpm. Then 300 ml of water was added to resuspend the precipitate (using a sonotrode, magnetic stirring). With vigorous stirring, 125 ml of a 100 g / l sodium tripolyphosphate solution was added to the colloidal suspension thus obtained. The suspension thus became more stable. The suspension was then sonicated at using a sonotrode. The suspension was then centrifuged for 15 minutes at 8000 rpm. The pellet was then redispersed in 150 ml of water. Then the suspension obtained was centrifuged again for 15 minutes at 8000 rpm and the pellets obtained redispersed in 300 ml of ethanol in order to obtain a suspension suitable for electrophoretic deposition. Agglomerates of approximately 100 nm consisting of primary Li3PO4 particles of 10 nm were thus obtained in suspension in ethanol. b. Production of a porous inorganic layer according to the invention based on a suspension of Li3PO4 nanoparticles i. Production of a mesoporous cathode based on LiCoO2 A suspension of crystalline LiCoO2 nanoparticles was prepared by hydrothermal synthesis. For 100 ml of suspension, the reaction mixture was prepared by adding 20 ml of a 0.5M aqueous solution of cobalt nitrate hexahydrate added under stirring to 20 ml of a 3M solution of lithium hydroxide monohydrate followed by dropwise addition of 20 ml of 50% H2O2. The reaction mixture was placed in an autoclave at 200°C for 1 hour; the pressure in the autoclave reached approximately 15 bar. A black precipitate was obtained in suspension in the solvent. This precipitate was subjected to a succession of centrifugation and redispersion steps in water, until a suspension with a conductivity of approximately 200 pS / cm and a zeta potential of -30 mV was obtained. The size of the primary particles was in the order of 10 nm to 20 nm and the aggregates had a size between 100 nm and 200 nm. The product was characterized by X-ray diffraction and electron microscopy. These aggregates were deposited by electrophoresis on 5 μm thick stainless steel strips in an aqueous medium, applying pulsed currents of 0.6 A peak and 0.2 A average; the applied voltage was of the order of 4 to 6 V for 400 s. This resulted in a deposit of approximately 4 μm thickness. It was consolidated at 600°C for 1 h in air in order to weld the nanoparticles together, improve adhesion to the substrate and complete the recrystallization of LiCoO2. ii. Production of a mesoporous anode based on Li4Ti50i2 A suspension of Li4Ti50i2 nanoparticles was prepared by glycothermal synthesis: 190 ml of 1,4-butanediol was poured into a beaker, and 4.25 g of lithium acetate was added with stirring. The solution was kept stirring until the acetate is completely dissolved. 16.9 g of titanium butoxide were taken under an inert atmosphere and introduced into the acetate solution. The solution was then stirred for a few minutes before being transferred to an autoclave previously filled with an additional 60 ml of butanediol. The autoclave was then closed and purged with nitrogen for at least 10 minutes. The autoclave was then heated to 300 °C at a rate of 3 °C / min and maintained at this temperature for 2 hours, with stirring. At the end, it was allowed to cool, still with stirring. A white precipitate was obtained in suspension in the solvent. This precipitate was subjected to a succession of centrifugation - redispersion steps in ethanol to obtain a pure colloidal suspension, with low ionic conductivity. It comprised aggregates of approximately 150 nm made up of 10 nm primary particles. The zeta potential was of the order of -45 mV. The product was characterized by X-ray diffraction and electron microscopy. Figure 2(a) shows a diffractogram, Figure 2(b) a transmission electron microscopy image of primary particles. These aggregates were deposited by electrophoresis on 5 μm thick stainless steel strips in aqueous medium, applying pulsed currents of 0.6 A peak and 0.2 A average; the applied voltage was of the order of 3 to 5 V for 500 s. This resulted in a deposit of approximately 4 μm thickness. It was consolidated by RTA annealing at 40% power for 1 s under nitrogen in order to weld the nanoparticles together, improve adhesion to the substrate and perfect the recrystallization of Li4Ti50i2. iii. Production on the anode and cathode layers previously developed of a porous inorganic layer from the suspension of Li3PO4 nanoparticles previously described in part a) Porous thin films of Li3PO4 were then electrophoretically deposited on the surface of the previously prepared anode and cathode by applying an electric field of 20V / cm to the previously obtained Li3PO4 nanoparticle suspension for 90 seconds to obtain a layer with a thickness of approximately 1.5 μm. This layer was air-dried at 120°C to remove any traces of organic residues, and then it was calcined at 350°C for one hour in air. Example 2: Construction of an electrochemical cell After depositing 1.5 pm of porous Li3PO4 on each of the electrodes (LiCoO2 and Li4Ti50i2) previously developed, the two subsystems were stacked in a until the Li3PO4 films were in contact. This stack was then hot-pressed under vacuum. To do this, the stack was placed under a pressure of 1.5 MPa and then dried under vacuum for 30 minutes at 10'3 bar. The press plates were then heated to 5,450 °C at a rate of 4 °C / second. At 450 °C, the stack was then thermo compressed under a pressure of 45 MPa for 1 minute, then the system was cooled to room temperature. Once the assembly was completed, a rigid, multi-layer system consisting of one or more assembled battery cells was obtained. 10 This assembly was then impregnated in an electrolytic solution comprising PYR14TFSI and LiTFSI at 0.7 M. The ionic liquid instantly enters the porosities by capillarity. The system was kept immersed for 1 minute, then the surface of the cell stack was dried by a blade of N2. 15

Claims

CLAIMS 1. Thin-film electrolyte in an electrochemical device such as a lithium ion battery, said electrolyte comprising a porous inorganic layer impregnated with a lithium ion-carrying phase, characterized in that said porous inorganic layer has an interconnected network of open pores and in that the open pores of said porous inorganic layer have an average diameter D5o of less than 100 nm, preferably less than 80 nm, preferably between 2 nm and 80 nm, and even more preferably between 2 nm and 50 nm, and a volume greater than 25% of the total volume of said thin-film electrolyte, and preferably greater than 30%.

2. Thin-film electrolyte according to claim 1, characterized in that the open pores of said porous inorganic layer have a volume of between 30% and 50% of the total volume of said thin-film electrolyte.

3. Thin-film electrolyte according to claim 1 or 2, characterized in that said porous inorganic layer is free of organic binder.

4. Thin-film electrolyte according to any one of claims 1 to 3, characterized in that its thickness is less than 10 μm and preferably between 2.5 and 4.5 μm.

5. Thin-film electrolyte according to any one of claims 1 to 4, characterized in that said porous inorganic layer comprises an electronically insulating material, preferably chosen from AI2O3, SiO2, ZrO2, and / or a material selected from the group formed by: o garnets of formula Lid A1X A2y(TO4)z where ■ A1 represents a cation of oxidation state +II, preferably Ca, Mg, Sr, Ba, Fe, Mn, Zn, Y, Gd; and where ■ A2 represents a cation of oxidation state +III, preferably Al, Fe, Cr, Ga, Ti, La; and where ■ (TO4) represents an anion in which T is an atom with oxidation number +IV, located at the center of a tetrahedron formed by oxygen atoms, and in which TO4 advantageously represents the silicate or zirconate anion, knowing that all or part of the T elements with oxidation number +IV can be replaced by atoms with an oxidation state of +111 or +V, such as Al, Fe, As, V, Nb, In, Ta; ■ knowing that: d is between 2 and 10, preferably between 3 and 9, and even more preferably between 4 and 8; x is between 2.6 and 3.4 (preferably between 2.8 and 3.2); y is between 1.7 and 2.3 (preferably between 1.9 and 2.1) and z is between 2.9 and 3.1; o garnets, preferably chosen from: Li7La3Zr20i2; Li6La2BaTa20i2; Li5.5La3Nbi.75lno.250i2; Li5La3M20i2 with M = Nb or Ta or a mixture of the two compounds; Li7-xBaxLa3xM20i2 with 0 <x<1 et M = Nb ou Ta ou un mélange des deux composés ; le Li7-xLa3Zr2-xMxOi2 avec 0<x<2 et M = Al, Ga ou Ta ou un mélange de deux ou trois de ces composés ; o lithium phosphates, preferably chosen from: lithium phosphates of the NaSICON type, U3PO4; LiPOs; Li3Alo,4Sci,6(P04)3 called “LASP”; Li3(Sc2-xMx)(PO4)3 with M=AI or Y and 0 < x < 1; Lii+xMx(Sc)2-x(PO4)3 with M = Al, Y, Ga or a mixture of the three compounds and 0 < x < 0.8; Lii+xMx(Gai-yScy)2-X(PO4)3 with 0 < x < 0.8; 0 < y < 1 and M= Al or Y or a mixture of the two compounds; Lii+xMx(Ga)2-x(PO4)3 with M = Al, Y or a mixture of the two compounds and 0 < x < 0.8; the Lii+xAlxTi2x(PO4)3 with 0 < x < 1 called “LATP”; or the Lii+xAlxGe2-x(PO4)3 with 0 < x < 1 called “LAGP”; or the Lii+x+zMx(Gei-yTiy)2-xSizP3-zOi2 with 0 <x<0,8 et 0<y<1,0 et 0<z<0,6 et M= Al, Ga ou Y ou un mélange de deux ou trois de ces composés ; le Li3+y(Sc2-xMx)QyP3-yOi2 avec M = Al et / ou Y et Q = Si et / ou Se, 0 < x < 0,8 et 0 < y < 1 ; ou le Lii+x+yMxSc2-xQyP3-yOi2 avec M = Al, Y, Ga ou un mélange des trois composés et Q = Si et / ou Se, 0 < x < 0,8 et 0 < y < 1 ;or Lii+x+y+zMx(Gai-ySCy)2-xQzP3-zOi2 with 0 < x < 0.8, 0 < y < 1, 0 < z < 0.6 with M = Al or Y or a mixture of the two compounds and Q= Si and / or Se; or Lii+xM3xM2xP30i2 with 0 < x < 1 and M3= Cr and / or V, M = Sc, Sn, Zr, Hf, Se or Si, or a mixture of these compounds; o lithium borates, preferably chosen from: Li3(Sc2-xMx)(BO3)3 with M=Al or Y and 0 < x < 1; Lii+xMx(Sc)2-x(BO3)3 with M = Al, Y, Ga or a mixture of the three compounds and 0 < x < 0.8; Lii+xMx(Gai-yScy)2-x(BO3)3 with 0 < x < 0.8, 0 < y < 1 and M= Al or Y; Lii+xMx(Ga)2-x(BO3)3 with M = Al, Y or a mixture of the two compounds and 0 < x < 0.8; Li3BO3, Li3BO3-Li2SO4, Li3BO3-Li2SiO4, Li3BO3-Li2SiO4-Li2SO4; o oxynitrides, preferably chosen from Li3PO4-xN2x / 3, Li4SiO4-xN2x / 3, Li4GeO4-xN2x / 3 with 0 < x < 4 or Li3BO3-xN2x / 3 with 0 < x < 3; o lithium compounds based on lithium and phosphorus oxynitride, called “LiPON”, in the form of LixPOyNz with x ~2.8 and 2y+3z ~7.8 and 0.16 < z < 0.4, and in particular Li2.9PO3.3N0.46, but also the compounds LiwPOxNySz with 2x+3y+2z = 5 = w or the compounds LiwPOxNySz with 3.2 < x < 3.8, 0.13 < y < 0.4, 0 < z < 0.2, 2.9 < w < 3.3 or the compounds in the form of LitPxAlyOuNvSw with 5x+3y=5, 2u+3v+2w=5+t, 2.9 <t<3,3, 0,84<x<0,94, 0,094<y<0,26, 3.2 <u<3,8, 0,13<v<0,46, 0<w<0,2 ; o materials based on lithium phosphorus or boron oxynitrides, called respectively “LiPON” and “LIBON”, which may also contain silicon, sulfur, zirconium, aluminum, or a combination of aluminum, boron, sulfur and / or silicon, and boron for materials based on lithium phosphorus oxynitrides; o lithium compounds based on lithium, phosphorus and silicon oxynitride called “LiSiPON”, and in particular Li1.9Si0.28P1.0O1.1N10; o lithium oxynitrides of the types LiBON, LiBSO, LiSiPON, LiSON, thio-LiSiCON, LiPONB (where B, P and S represent boron, phosphorus and sulfur respectively); o lithium oxynitrides of LiBSO type such as (1-x)LiBO2- xLi2SO4 with 0.4 < x < 0.8; o lithiated oxides, preferably chosen from Li7La3Zr20i2 or Li5+xLa3(Zrx,A2-x)Oi2 with A=Sc, Y, Al, Ga and 1.4 < x < 2 or Li0.35Lao,55Ti03 or Li3xLa2 / 3-xTiO3 with 0 < x< 0.16 (LLTO); o silicates, preferably chosen from Li2Si2O5, Li2SiOs, Li2Si20e, LiAISiO4, Li4SiO4, LiAISi2Oe; o solid electrolytes of anti-perovskite type chosen from: Li3OA with A a halide or a mixture of halides, preferably at least one of the elements chosen from F, Cl, Br, I or a mixture of two or three or four of these elements; Li(3-x)Mx / 2OA with 0 < x < 3, M a divalent metal, preferably at least one of the elements chosen from Mg, Ca, Ba, Sr or a mixture of two or three or four of these elements, A a halide or a mixture of halides, preferably at least one of the elements chosen from F, Cl, Br, I or a mixture of two or three or four of these elements; Li(3-x)M3x / 3OA with 0 < x < 3, M3 a trivalent metal, A a halide or a mixture of halides, preferably at least one of the elements chosen from F, Cl, Br, I or a mixture of two or three or four of these elements; or LiCOXzY(iZ), with X and Y halides as mentioned above in relation to A, and 0 < z < 1, o the compounds Lao,5iLio,34Ti2.94, Li3.4V0.4Geo,604, Li2O-Nb2O5, LiAIGaSPO4; o formulations based on Li2CO3, B2O3, Li2O, AI(PO3)3LiF, P2Ss, Li2S, Li3N, Lii4Zn(GeO4)4, Li3,6Geo,eVo,404, LiTi2(PO4)3, Li3,2sGeo,25Po,25S4, Lii.sAlo.sTii,7(PO4)3, Lii+xAlxM2-x(PO4)3 (where M = Ge, Ti, and / or Hf, and where 0 < x < 1), Lii+x+yAlxTi2.xSiyP3-yOi2 (where 0 <x<1 et 0<y<1).

6. Thin-film electrolyte according to any one of claims 1 to 5, characterized in that said pores are impregnated with a phase carrying lithium ions, such as an organic solvent or a mixture of solvents in which at least one lithium salt is dissolved, and / or a polymer containing at least one lithium salt, and / or an ionic liquid or a mixture of ionic liquids, possibly diluted with a suitable solvent, containing at least one lithium salt.

7. Method for manufacturing a thin-film electrolyte as defined in claims 1 to 6 deposited on an electrode, said layer preferably being free of organic binder and preferably having a porosity, preferably mesoporous, greater than 30% by volume, and even more preferably between 30% and 50% by volume, and said layer having pores with an average diameter D5o of less than 100 nm, preferably less than 80 nm and preferably less than 50 nm, said method being characterized in that: (a) a colloidal suspension comprising aggregates of nanoparticles of at least one inorganic material is supplied, said aggregates having an average diameter of between 80 nm and 300 nm (preferably between 100 nm and 200 nm), (b) an electrode is supplied, (c) a porous inorganic layer is deposited on said electrode by electrophoresis or by dip-coating, from a suspension of particles of inorganic material obtained in step (a); (d) drying said porous inorganic layer, preferably under an air flow to obtain a porous inorganic layer; (e) said porous inorganic layer is treated by mechanical compression and / or heat treatment, (f) said porous inorganic layer obtained in step (e) is impregnated with a phase carrying lithium ions.

8. Method for manufacturing a thin-film electrolyte as defined in claims 1 to 6 deposited on an electrode, said layer preferably being free of organic binder and preferably having a porosity, preferably mesoporous, greater than 30% by volume, and even more preferably between 30% and 50% by volume, and said layer having pores of average diameter D5o less than 100 nm, preferably less than 80 nm, preferably less than 50 nm, said method being characterized in that: (a1) a colloidal suspension comprising nanoparticles of at least one inorganic material P with an average primary diameter D5o less than or equal to 50 nm is supplied; (a2) the nanoparticles present in said colloidal suspension are destabilized so as to form aggregates of particles with an average diameter of between 80 nm and 300 nm, preferably between 100 nm and 200 nm, said destabilization preferably being carried out by adding a destabilizing agent such as a salt, preferably LiOH; (b) an electrode is supplied; (c) depositing on said electrode a porous inorganic layer by electrophoresis or by dip-coating, from said colloidal suspension comprising the aggregates of particles of at least one inorganic material obtained in step (a2); (d) drying the porous inorganic layer, preferably under an air flow to obtain a porous inorganic layer; (e) said porous inorganic layer is treated by mechanical compression and / or heat treatment, (f) said porous inorganic layer obtained in step (e) is impregnated with a phase carrying lithium ions.

9. Method according to claims 7 or 8, in which the porous inorganic layer obtained in step (c) has a thickness of less than 10 pm, preferably less than 8 pm, and even more preferably between 1 pm and 6 pm.

10. Method according to any one of claims 7 to 9, in which the porous inorganic layer obtained in step (d) has a thickness of less than 10 μm, preferably between 2.5 μm and 4.5 μm.

11. Method according to any one of claims 7 to 10, in which the primary diameter of said nanoparticles is between 10 nm and 50 nm, preferably between 10 nm and 30 nm.

12. Method according to any one of claims 7 to 11, in which the average diameter of the pores is between 2 nm and 50 nm, preferably between 6 nm and 30 nm and even more preferably between 8 nm and 20 nm.

13. A method according to any one of claims 7 to 12, wherein the electrode is a dense electrode or a porous electrode, preferably a mesoporous electrode.

14. Use of a method according to any one of claims 7 to 13 for the manufacture of thin-film electrolytes, in electronic, electrical or electrotechnical devices, and preferably in devices selected from the group formed by: batteries, capacitors, supercapacitors, capacitors, resistors, inductors, transistors.

15. Method for manufacturing a thin-film battery, implementing the method according to one of claims 7 to 13 and comprising the steps of: -1- supply of at least two conductive substrates, previously covered with a layer of a material which can serve as an anode and respectively as a cathode (“anode layer” respectively “cathode layer”), -2- supply of a colloidal suspension comprising aggregates of nanoparticles of at least one inorganic material, said aggregates having an average diameter of between 80 nm and 300 nm (preferably between 100 nm and 200 nm), -3- Deposition of a porous inorganic layer by electrophoresis or by dip-coating, from a suspension of aggregated particles of inorganic material obtained in step -2- on the cathode or anode layer obtained in step -1-, -4- Drying of the layer thus obtained in step -3-, preferably under a flow of air, -5- Stacking of the cathode and anode layers laterally offset, -6- Treatment of the stacking of the anode and cathode layers obtained in step -5- by mechanical compression and / or heat treatment so as to juxtapose the porous inorganic layers present on the anode and cathode layers, -7- Impregnation of the structure obtained in step -6- with a phase carrying lithium ions leading to the production of a battery.

16. The method of claim 15, wherein the cathode is a dense electrode or a dense electrode coated by ALD with an electronically insulating layer, preferably an electronically insulating and ionically conductive layer, or a porous electrode, or a porous electrode coated by ALD with an electronically insulating layer, preferably an electronically insulating and ionically conductive layer, or, preferably, a mesoporous electrode, or a mesoporous electrode coated by ALD with an electronically insulating layer, preferably an electronically insulating and ionically conductive layer, and / or in which the anode is a dense electrode or a dense electrode coated by ALD with an electronically insulating layer, preferably an electronically insulating and ionically conductive layer, or a porous electrode or a porous electrode coated by ALD with an electronically insulating layer, preferably an electronically insulating and ionically conductive layer, or, preferably, a mesoporous electrode, or a mesoporous electrode coated by ALD with an electronically insulating layer, preferably an electronically insulating and ionically conductive layer.

17. Method according to any one of claims 15 to 16, in which after step -7-: - we successively place, alternately, on the battery: ■ at least a first layer of parylene and / or polyimide on said battery, ■ at least one second layer composed of an electrically insulating material by ALD (Atomic Layer Deposition) on said first layer of parylene and / or polyimide, ■ and on the alternating succession of at least a first and at least a second layer is deposited a layer making it possible to protect the battery against mechanical damage to the battery, preferably made of silicone, epoxy resin or parylene, or polyimide, thus forming a battery encapsulation system, - the encapsulated battery is cut along two cutting planes to expose the anode and cathode connections on each of the cutting planes. the battery, so that the encapsulation system covers four of the six faces of said battery, preferably continuously, - we successively deposit, on and around, these anodic and cathodic connections: ■ a first electronically conductive layer, preferably metallic, optional, preferably deposited by ALD, ■ a second layer based on silver-filled epoxy resin, deposited on the first electronically conductive layer, and ■ a third nickel-based layer, deposited on the second layer, and ■ a fourth layer based on tin or copper, deposited on the third layer.

18. The method of claim 17, wherein the anodic and cathodic connections are on opposite sides of the stack.

19. Electrochemical device comprising at least one thin layer of electrolyte according to any one of claims 1 to 6, preferably a lithium ion battery or a supercapacitor.

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