Field of the invention This invention relates to the field of batteries and particularly lithium ion batteries. It most particularly concerns all-solid-state lithium ion batteries and a new process for making such batteries in thin films. State of the art The ideal battery for supplying power to standalone electrical devices (such as telephones and laptop computers, portable tools, standalone sensors), or for traction of electrical vehicles would have long life, would be capable of storing large quantities of energy and power and there would be no risk of overheating or possibly even explosion. At the present time, these electrical devices are powered essentially by lithium ion batteries (herein called "Li-ion" batteries) that have the best energy density among the various proposed storage technologies. However, Li-ion batteries can be made using different architectures and with different chemical compositions of their electrodes. Processes for making Li-ion batteries are presented in many articles and patents and the “Advances in Lithium-Ion Batteries” book (published by W. van Schalkwijk and B. Scrosati) in 2002 (Kluever Academic / Plenum Publishers) gives a good inventory of these processes. Li-ion battery electrodes can be made using printing techniques (particularly roll coating, doctor blade, tape casting). These techniques can be used to make deposits between 50 and 400 μm thick. The power and energy of the battery can be modulated, by varying the thickness of the deposits and their porosity and the size of active particles. Inks (or pastes) deposited to form electrodes contain particles of active materials and also binders (organic), carbon powder to make the electrical contact between particles, and solvents that are evaporated during the electrode drying step. A calendering step is performed on the electrodes to improve the quality of electrical contacts between particles and to compact the deposits. After this compression step, active particles of the electrodes occupy about 60% of the volume of the deposit, which means that there is usually 40% porosity between particles. Pores are filled with an electrolyte. These batteries also comprise a separator placed between the anode and the cathode. The separator is a porous polymer film about 20 μm thick. The electrolyte will be added during the final assembly of the battery when the anode and the cathode are stacked or rolled with the separator between them. The electrolyte migrates into the pores contained in the separator and also in the electrodes and thus provides ionic conduction between the electrodes. It may be liquid (aprotic solvent in which a lithium salt is dissolved) or in 2 the form of a more or less polymerized gel impregnated with a lithium salt. Binders used in the formulation of inks also contribute to the transport of lithium ions. They are impregnated with electrolyte that may be either an aprotic organic solvent containing a lithium salt or an ionic liquid. The power and energy of a battery may be varied by varying the thickness of the deposits and the size and density of the active particles contained in the ink. An increase in the energy density is necessarily at the detriment of the power density. High power battery cells necessitate the use of thin very porous electrodes and separators, while on the contrary an increase in the energy density is achieved by increasing these thicknesses and reducing the porosity. The article “Optimization of Porosity and Thickness of a Battery Electrode by Means of a Reaction-Zone Model” by John Newman, published in J. Electrochem. Soc., Vol. 142, No.1 in January 1995, demonstrates the corresponding effects of electrode thicknesses and their porosity on their discharge rate (power) and energy density. However, an increase in porosity tends to increase risks of short circuits internal to the battery cell. Metal lithium can precipitate in the pores. Similarly, if electrode particles are too small, they can detach from the electrode and migrate into these pores. Furthermore, electrolytes based on organic solvents and lithium salts tend to degrade (oxidize) under the effect of high electrical potentials and/or excessive temperatures and traces of humidity. This degradation can be slow and continuous during exposure of the battery cell to a temperate external environment (aging) but it can also become fast and sudden in the case of overheating or overload. Evaporation and combustion of this electrolyte can then initiate a violent reaction that can cause the cell to explode. Dense polymer films conducting lithium ions may be used as separators to reduce these risks. These films are also more resistive and they must be thin to not degrade performances of the battery excessively because their ionic conductivity is low. Current techniques for the fabrication of polymer films and their poor mechanical properties make it impossible to obtain thicknesses of less than 30 μm to 40 μm. For example this is disclosed in patent application WO 2004/051769 (Avestor Ltd Partnership). Ceramic particles that might conduct lithium ions have been added as disclosed in patent application EP 1 049 188 A1 (Ohara KK) to improve the mechanical properties of polymer films. However, film thicknesses obtained are still close to 20 μm. Patent application EP 1 424 743 A1 (Ohara KK) discloses the deposition of an electrolyte film directly onto the surface of the electrodes in order to further reduce these film thicknesses. One of the processes disclosed consists of coating the surface of an electrode with an ink containing a polymer electrolyte and particles of inorganic solid electrolyte conducting lithium ions. 3 Furthermore, polymer films obtained by these techniques only cover electrode surfaces, while electrode edges remain bare. The dielectric insulation on the edges of the cells is not perfect and depends on the mechanical stresses and the precision with which these films are placed. This can give rise to small leakage currents that can induce a selfdischarge phenomenon or even a short circuit internal to the cell. Furthermore, the use of organic electrolytes containing lithium salts limits the choice of electrode materials that can be used, because most of them react to the strongly reducing or oxidizing potentials of anodes and cathodes. Another process for making electrolyte and electrode films has been proposed. This is to deposit a thin film of ceramics or vitro-ceramics conducting lithium ions and lithium insertion electrode materials under a vacuum. This technique can give dense films with no porosity and consequently excellent mechanical properties preventing the occurrence of internal short circuits in the battery. The absence of porosity means that lithium ions can be transported through the film by diffusion, without the need to use organic polymerbased or solvent-based electrolytes containing lithium salts. Such films can cover the entire electrode including its edges. Such all-inorganic films confer excellent aging, safety and temperature resistance properties. Furthermore, there are many advantages in manufacturing of dense high quality thin films with a more or less complex chemical composition that can contain several phases, not only for fabrication of high performance Li-ion batteries, but also for many other applications. Successive stacking of thin dense inorganic films in batteries can significantly increase the performance of Li-ion batteries. Different vacuum deposition techniques have been used for fabrication of dense thin films in batteries. In particular, CVD (Chemical Vapor Deposition) deposits are used for the fabrication of thin films in the field of electronics. This technique and all its variants (EVD, OMCVD) can give high quality and strongly bonding films but the deposition rate is low, of the order of 1 to 10 μm/h, and reaction processes may require high temperatures, possibly more than 600°C, that cannot be resisted by all types of substrate. Moreover, these techniques often impose the use of highly corrosive gases. Physical vapor deposition techniques also have disadvantages. "Thermal spray technology" techniques are suitable particularly for the fabrication of relatively thick deposits a few hundred microns thick, there are not very precise and they cannot be used to obtain perfectly homogeneous and controlled thin films. PVD (Physical Vapor 4 Deposition) techniques cover several variants depending on the spraying mode. Compounds to be deposited may be vaporized by RF (radio frequency) excitation or may be ion beam assisted (IBAD). The deposition rate obtained with such technologies is of the order of 0.1 μm to 1 μm per hour. PVD deposition techniques can result in very good quality deposits containing almost no isolated defects, and can be used to make deposits at relative low temperatures. However, due to the difference in the evaporation rate between the different elements, it is difficult to deposit complex alloys with such techniques and to control the stoichiometry of the deposit. This technique is perfectly suitable for making thin films, but as soon as an attempt is made to increase the thickness of the deposit (for example thicknesses of more than 5 μm), columnar growth occurs and the deposition time becomes too long to envisage industrial use in the field of thin film microbatteries. PVD deposition is the most frequently used technique for fabrication of thin film microbatteries. These applications require films with no porosity and no other isolated defects to guarantee low electrical resistivity and good ionic conduction necessary for these devices to work correctly. However, vacuum deposition techniques used to make such films are very expensive and difficult to implement industrially over large areas with high productivity. Other technologies currently available for making thin films include embodiments based on consolidation of compact particle deposits. These techniques include the production of deposits by sol-gel processes. This technique consists of depositing a polymeric lattice on the surface of a substrate obtained after hydrolysis, polymerization and condensation steps. The sol-gel transition appears during evaporation of the solvent that accelerates reactional processes on the surface. This technique can be used to make compact and very thin deposits. The films thus obtained are of the order of a hundred nanometers thick. Successive steps should be performed to increase the thickness of the deposit without inducing risks of cracks or crazing occurring. Consequently, this technique creates industrial productivity problems as soon as an attempt is made to increase the thickness of the deposit. The inking techniques described above can be used to make thin deposits. However, a fluid ink is essential if deposits between 1 and 5 micrometers thick are to be obtained. The fluidity of inks depends on the content of dry extracts, particle sizes and the nature of the solvent and any organic compounds dissolved in this ink. In order to make thin film deposits, the dry extract has to be reduced and excessively small particle sizes are impossible (sizes larger than about a hundred nanometers). On the other hand, this increase in the solvent quantity increases risks of forming cracks, cavities and clusters in 5 the deposit during the drying phases. The deposits then become very difficult to compact. Final compaction of the deposit is obtained by evaporation of the solvent contained in the ink. This drying step is difficult to control because regions with lower densities and locally lower porosity will dry faster than areas with higher densities. Capillary effects induced by these local differences in drying will cause zones with higher densities that are still impregnated to group together. The only way to consolidate these deposits is compaction under very high pressures (with the required pressure increasing as the particle size reduces) and/or sintering at high temperatures close to the melting temperature of the material forming the particles. Very high temperatures are necessary to consolidate the initially porous structure. Temperature rises are difficult to control if it is required that shrinkage accompanying infilling of these pores in the thickness of the deposit does not lead to cracks. Furthermore, not all substrates resist such temperatures, and also the thickness of the deposit cannot be precisely controlled using the current liquid phase deposition techniques disclosed above. Finally, there is another alternative for deposition of materials in thin films in electrochemical devices and particularly in batteries. This is an electrophoretic particle deposition. For example, patent application US 7,662,265 (Massachusetts Institute of Technology) discloses the fabrication of thin film electrochemical devices (including batteries) by electrophoresis in which one of the electrodes (anode or cathode) and the solid electrolyte are obtained simultaneously, the other electrode having already been formed by electrophoretic deposition. Many cathode materials are mentioned, particularly LiCoO2, and LiFePO4, and the solid electrolytes mentioned are polymer electrolytes. Patent US 6,887,361 (University of California) discloses a process to form a ceramic porous membrane on an electrochemical device substrate in the solid state. Deposition is made by electrophoresis of a suspension of ceramic particles in isopropylic alcohol followed by drying and sintering. The process is applicable essentially to solid oxide fuel cells (SOFC). Patent applications US 2007/184345, WO 2007/061928, US 2008/286651 and WO 2010/011569 (Infinite Power Solutions) disclose electrochemical devices comprising a cathode deposited by techniques other than vacuum deposition; in particular they disclose deposition of a cathode film by electrophoresis from a micronic sized powder of LiCoO2; however, this film comprises cavities and it must be consolidated by sintering at high temperature close to the melting temperature of the deposited material. Other parts of the battery are obtained by vacuum deposition. 6 Patent US 7,790,967 (3G Solar Ltd) also discloses the deposition of a nanoporous electrode made of TiO2 by electrophoresis starting from a suspension of TiO2 nanoparticles. The electrode thickness is of the order of 10 μm. Some documents describe the use of electrophoresis for making some parts of thin film batteries; electrophoresis as described in these documents leads to porous films. Patent JP 4501247 (DENSO) discloses a process for fabrication of an electrode for a battery in which a film of an active material is formed by electrophoresis. More specifically, this patent discloses a process in which a charge collector is dipped in a solution comprising an active material in a solvent, this process being part of a more general process for fabrication of an electrode for a battery. Electrophoresis of said active material contained in the solution is done by generating an electric potential gradient in this solution, the active material forming a film of active material on the surface of the collector and bonding to said collector surface. Fabrication of cathodes for Li-ion batteries using this process is mentioned. Techniques used to make the anode and the electrolyte are not mentioned. Patent application JP 2002-042792 (DENSO) discloses a process for depositing a solid electrolyte on an electrode of a battery, the deposit being made by electrophoresis; no consolidation is done after the deposition. The electrolytes considered are essentially polymer electrolytes and lithium iodide. Purposes of the invention A first purpose of this invention is the fabrication of all-solid-state thin film batteries with films that have excellent geometric precision, particularly precisely-controlled thickness and a very small number of defects, using a process providing a high deposition rate with low investment and operating costs. Another purpose of the invention is to fabricate thin film batteries using a process that is easily implemented industrially and that causes little pollution. Another purpose of the invention is to disclose a very simple process for making thin films with various chemical compositions. Another purpose is to fabricate batteries with a better power density and a better energy density. Yet, another purpose is to fabricate longer life batteries that can resist exposure to high temperatures without deteriorating. 7 These objectives are achieved using a process for fabrication of all-solid-state thin film batteries, said batteries comprising a film of anode materials (anode film), a film of solid electrolyte materials (electrolyte film) and a film of cathode materials (cathode film), each of these three films being deposited by an electrophoresis process, knowing that the anode film and the cathode film are each deposited on a conducting substrate, preferably a thin metal sheet or band or a metalized plastic sheet or band or a metalized insulating film, at least one of said conducting substrates being useable as a battery current collector, and the film of solid electrolyte material is deposited on the anode and/or cathode film, and knowing that said process also comprises at least one step in which said sheets or bands are stacked so as to form at least one battery with a “collector / anode / electrolyte / cathode / collector” type of stacked structure. Advantageously, this process also comprises at least one so-called consolidation step to increase the density of at least one of the films deposited by electrophoresis, this at least one consolidation step possibly being done on the conducting substrate with at least one anode film or at least one cathode film, said at least one anode film or cathode film possibly being coated with at least one electrolyte film, and said at least one consolidation step possibly being done before stacking and/or on the stacked structure, said at least one consolidation step comprising a mechanical compaction step and/or an annealing step at a temperature TR that preferably does not exceed 0.7 times the melting or decomposition temperature (expressed in °C) and preferably does not exceed 0.5 times (and even more preferably does not exceed 0.3 times) the melting or decomposition temperature of the anode, cathode or electrolyte material with the lowest melting temperature on which said annealing step is carried out. More particularly, these objectives are achieved by the use of a fabrication process for an all-solid-state thin film battery comprising steps of: (a) Providing a first colloidal suspension “SP+” containing “P+” particles, called a “cathode materials” suspension; (b) Providing a second colloidal suspension “SP-” containing “P-” particles, called an “anode materials” suspension; (c) Providing a third colloidal suspension “SPn” containing “Pn” particles, called a conducting “solid electrolyte materials” suspension; (d) Providing conducting substrates, preferably in the form of a band or sheet; (e) Immersing a first conducting substrate in a bath of said SP+ suspension containing cathode materials in the presence of a counter-electrode, followed by application of an electrical voltage between said first conducting substrate and said counter electrode so as 8 to obtain an electrophoretic deposit containing P+ particles of cathode materials on said first substrate of conducting material; (f) Immersing a second conducting substrate in a bath of said SP- suspension containing anode materials in the presence of a counter electrode, followed by application of an electric voltage between said second substrate and said counter electrode so as to obtain an electrophoretic deposit containing P- particles of anode materials on said substrate of conducting material; (g) Immersing the first substrate coated in step (e) and/or the second substrate coated in step (f) in a bath of said SPn suspension of Pn particles of solid electrolyte materials in the presence of a counter electrode, followed by application of an electric voltage between said first and/or second coated substrate and the counter electrode so as to obtain an electrophoretic deposit of inorganic solid electrolyte material particles on said substrate(s); (h) Assembling (stacking) cathode and anode substrates to obtain a battery. Advantageously, said P+ and/or P- and/or Pn particles are nanoparticles. The order of steps (a), (b), (c) and (d) is not important in this process; similarly, the order of steps (e) and (f) is not important. The substrate can be cut before step (g). Another purpose of this invention is to make electrophoretic deposits on substrates that cannot resist very high temperatures. This purpose is achieved using the process in which step (h) comprises a mechanical consolidation and/or low temperature (TR) sintering step done one after the other or simultaneously, or in which step (h) is followed by such a step. The temperature TR advantageously does not exceed 600°C. In some embodiments, it does not exceed 400°C. The so-called consolidation step is aimed at increasing the density of at least one of the films deposited by electrophoresis, this step possibly being done on the conducting substrate with at least one anode film or at least one cathode film, said at least one anode or cathode film possibly being coated with at least one electrolyte film before stacking and/or on the stacked structure. Said consolidation step comprises at least one mechanical compaction step and/or a heat treatment (annealing) step at a temperature TR that preferably does not exceed 0.7 times the melting or decomposition temperature (expressed in °C), and preferably does not exceed 0.5 times (and even more preferably does not exceed 0.3 times) the melting or decomposition temperature (expressed in °C) of the anode, cathode or electrode material with the lowest melting temperature on which this annealing is done. The “melting 9 temperature” term in this case refers to the decomposition temperature for the case of substances for which there is no melting point. In any case, it is preferable not to exceed a temperature TR of 600°C, and in some embodiments not to exceed 400°C. When the two steps (mechanical and heat treatment) are done, the heat treatment may be done before or after compaction or the two steps may be done simultaneously. At least one and preferably all of the films deposited by electrophoresis are consolidated. This consolidation can be done on each substrate before and/or after the deposition of the electrolyte and/or after the assembly or stacking step. Very advantageously, a consolidation step is done after the assembly or stacking step in order to obtain good bonding between the electrolyte films (in the case in which an electrolyte is deposited on each electrode) or between the electrode film and the electrolyte that is deposited on said electrode film. Consolidation is possible using a mechanical process, for example by passing between two rollers, or by pressing (preferably isostatic) or by shock, or by heat treatment, or by a combination of these processes. Thermal consolidation may be preceded, followed or accompanied by one or several mechanical consolidation steps. In one particular embodiment, consolidation and particularly heat treatment is done under a vacuum or under an inert atmosphere. Deposition by electrophoresis is preferably done with a colloidal suspension of particles smaller than 1 μm, preferably smaller than 100 nm, or even smaller than 30 nm. The use of nanoparticles, preferably smaller than 100 nm and even more preferably less than 30 nm, can give high density after consolidation. This density advantageously reaches 85%, and preferably 90%, and even more preferably 95% of the theoretical density of the solid substance. Advantageously, the porosity of at least one of the films after consolidation is less than 15%, preferably less than 10% and even more preferably less than 5%. In the process according to the invention, the average size D50 of nanoparticles in the anode, cathode and/or solid electrolyte material is preferably less than 1 μm, more preferably less than 100 nm, and even more preferably the nanoparticles are smaller than 50 nm and even better smaller than 30 nm. This makes it possible to consolidate thin films thermally at a lower temperature. This is why approximately spherical or cubic-shaped particles are preferred. The average grain size in at least one of the anode, cathode and/or electrolyte films after thermal consolidation is less than 1 μm; this increases the life of the battery, probably 10 because the local unbalance of the battery reduces. The heat treatment duration should be appropriate to prevent the risk of excessive (“parasitic”) growth of some grains. Another purpose of the invention is to obtain highly compact films after the deposition by electrophoresis, free particularly of cavities, cracks and clusters in order to facilitate consolidation at low temperature. In some embodiments, the zeta potential of the SP+, SP- and/or SPn colloidal suspensions provided in steps (a), (b) and (c) is greater than 40 mV, and even more preferably greater than 60 mV, to obtain stable suspensions not containing any particle clusters that could lead to defects in the deposited films. These suspensions can contain a steric or preferably electrostatic stabilizer. However, it is preferable that suspensions should not contain any stabilizer. Dry extracts from suspensions without stable stabilizers are advantageously between 2 and 20 g/L, the particle size preferably being smaller than 100 nm and even more preferably smaller than 50 nm. In this case, the Zeta potential of the suspension is usually less than 40 mV, and more particularly is between 25 and 40 mV. The electrophoretic deposition of nanoparticles can be facilitated by means of a step to deposit a compound designed to reduce the Zeta potential on conducting bands prior to the particle deposition step, before the deposition of the P+, P- and or Pn particles. Another purpose of the invention is the deposition of thin films with a very wide variety of chemical compositions that can associate several phases in order to increase functions of the deposits. This purpose is achieved through the use of the electrophoresis technique that makes it easy to deposit films using suspensions of particle mixes. Another purpose of the invention is to be able to very precisely control deposited thicknesses (within a thickness range varying from a few hundred nanometers to a few tens or even about a hundred micrometers). More precisely, it is required to have a process that guarantees perfect uniformity of the thickness over the entire surface of the deposit, even on rough or non-flat substrates, and excellent reproducibility and repeatability at industrial scale. It is also required to use a technique allowing a continuous and constant deposit on the edge of the substrates. In one advantageous embodiment, the thickness of the anode and/or cathode film after consolidation is less than 10 μm and is preferably less than 5 μm. The thickness of the electrolyte film after consolidation is advantageously less than 5 μm, preferably less than 2 μm and even more preferably less than 1 μm. Yet another purpose is to achieve optimum economy of the raw material. 11 These objectives are achieved through the use of electrophoresis and precise control of the deposition current throughout the deposition, knowing that deposition by electrophoresis will only occur on a sufficiently conducting substrate. Another purpose of the invention is an all-solid-state thin film battery capable of being fabricated by the process according to the invention; its energy density is preferably more than 250 Wh/kg and/or more than 500 Wh/liter. Yet another purpose is a thin film battery composed of several "collector / anode / electrolyte / cathode / collector" elements stacked in the form of a rigid single-piece structure not containing any lithium salt as electrolyte. Yet another purpose is a battery that can be obtained by the process according to the invention, also comprising at least one coating film containing metal elements, namely a termination film deposited on the edges of the electrodes, and an insulating protective film covering the other faces of the battery, such that said insulating protective film(s) and said at least one metal coating film form a hermetically sealed protection of the battery against ambient air. Description of the figures Figures 1(a), (b), (c) and (d) diagrammatically show films formed by stacking approximately isotropic shaped particles. Figure 1(e) shows a film deposited on a substrate using the PVD technique. Figure 1(a) diagrammatically shows a compact deposition of particles 2 on a substrate 1. All particles 2 are in contact with their adjacent particles 2a, 2b, 2c, 2d. Pores 3 are located between particles 2. The stack shown in this figure (and in figures 1(b), 1(c) and 1(d)) is deliberately less dense than a compact hexagonal stack, so that pores 3 between particles 2 are more easily visible. Figure 1(b) diagrammatically shows a compact deposition of particles 2 as can be obtained using the process according to the invention. Figure 1(c) shows a deposit of particles 2 on a substrate, the deposit having defects. These defects are essentially cavities 6 related to the presence of clusters 5; therefore these cavities 6 form inter-cluster pores, unlike the intra-cluster pores 3 that are at a much smaller geometric scale. In the case of a deposition using the process according to the invention, these clusters 5 are formed when the suspension used is not sufficiently stable. Figure 1(d) shows a deposit of particles with cracks that appeared after drying; these cracks may be open (through) cracks 7 or internal (non-through) cracks 8. 12 Figure 1(e) shows a dense deposit 4 as can be obtained using PVD type techniques; the porosity of these dense deposits is close to 0% because they are not formed by stacking particles. Figure 2 diagrammatically shows a stack or winding 10 of battery electrodes between which a separator 11 is positioned in batteries according to the state of the art. More precisely, each cathode 12 and each anode 14 is connected to its cathode collector 13 and anode collector 15 respectively, and each cathode 12 is separated from its anode 14 by a separator 11 that performs the function of transporting lithium ions through its electrolyte impregnated pores, and providing electrical insulation between the electrodes. If the separator 11 is badly positioned between the electrodes 12 and 14 (for example following a positioning fault, vibration, shock during fabrication), then a short circuit (or a leakage current) can appear between the electrodes 12, 14 in the defect 16 on the edge of the electrodes. Figures 3 to 25 show embodiments of the invention. Figures 3(a), 3(b), 3(c) and 3(d) and figure 4 show products obtained with four steps in a particular embodiment of the process according to the invention. Figures 5a, 5a’, 5b, 5b’, 5c, 5c’ show products obtained at different steps in a particular embodiment of the process according to the invention. Figures 6a, 6a’, 6b, 6b’, 6c, 6c’ show products obtained at different steps in a particular embodiment of the process according to the invention. Figures 7a, 7a’, 7b, 7b’, 7c, 7c’ show products obtained at different steps in a particular embodiment of the process according to the invention. Figures 8, 9, 10 and 11 show different types of batteries obtained at the end of the process according to the invention. Figures 12 and 13 each show one process for making cutouts on an electrode band. Figures 14a, 14b, 14c, 14d show products obtained at different steps in another particular embodiment of the process according to the invention in which the substrate on which the electrodes are deposited is a metalized polymer band. Figures 15a, 15b, 15c, 15d, 15e, 15f show products obtained at different steps in another particular embodiment of the process according to the invention, in which the substrate on which the electrodes are deposited is composed of bands of photosensitive polymer or polymer that can be used to make a stencil surrounding a metal film. 13 Figures 16a, 16b, 16c, 16d show products obtained at different steps in another particular embodiment of the process according to the invention, in which the substrate on which the electrodes are deposited is a polymer plate comprising metalized zones. The diagrams in figures 17 and 22 show typical embodiments of the process according to the invention. Figures 18a and 18b diagrammatically show devices for implementation of the process according to the invention. Figure 19 shows the principle for making a deposition by electrophoresis. Figure 20 is a diagrammatic representation of a deposition of two different sizes of nanoparticles. Figures 21a, 21b, 21c show lithium diffusion paths in different particle assembly configurations. Figure 21d shows the variation of porosity as a function of the density of the deposit. Figure 22 shows the steps in one embodiment of the process according to the invention. Figure 23a is a voltammetry curve for a suspension of Li4Ti5O12 particles with a dry extract of 10 g/L. Figure 23b is a voltammetry curve for a suspension of Li4Ti5O12 particles with a dry extract of 2g/L and a few ppm of citric acid. Figure 24 is a DLS diagram showing the distribution of the size of (Li1,3Al0,3Ti1,7(PO4)3) electrolyte particles in suspension. Figure 25 shows a battery like that in figure 11, also comprising coatings for protection against atmospheric gases. List of references 1 Substrate 2,2a,2b,2c,2d Particles 3 Pore 4 Film obtained by PVD deposition 5 Agglomerate 6 Cavity 7 Open crack 8 Non-open crack 9 Stencil 10 Battery according to the state of the art 11 Separator 14 12 Cathode 13 Cathode current collector 14 Anode 15 Anode current collector 16 Defects 17 Particles smaller than particles 2 20 Substrate 21 Anode 22, 22’, 22’’ Electrolyte 23, 23’, 23’’ Cut edge 24 Cathode 25 Connection between two electrolyte films 26 Electrical power supply, voltage source 27 Substrate and counter electrode 28 Deposit 29 Colloidal suspension 30 Particles 35,36 Electrical contacts, termination 41 Unwinder 42 Colloidal suspension 43 Counter electrode 44 Substrate (foil) 45 Drying oven 46 Mechanical compaction device 47 Drying the substrate coated with film deposited by electrophoresis 50 Substrate edge 60 Metal film coated with photosensitive resin 61, 61a, 61b Polymer film 62 Metal film of substrate 60 63 Cathode film 64a, 64b Stencil 65 Insulating substrate 66 Electrolyte film 67 Anode film 68a, 68b Metal films on insulating substrate 65 15 71 Cathode band 72 Anode band 73 Notch 74 Anode plate 75 Cathode plate 76 Surface contact zone between particles and the electrolyte contained in pores (low resistance diffusion path) 77 Point contact zone between particles (diffusion of lithium being limited on this point contact) 78 Welding of particles during consolidation that lead to the development of diffusion paths in the solid, for transport of electrical charges (electrons and ions) 79 Meltable phase that consolidated the particles to each other 80 Protective polymer film 81,82,83 Termination films 84 Overlap of the protective polymer film by termination films Detailed description of the invention For the purposes of this invention, “electrophoretic deposition” or “deposition by electrophoresis” refers to a film deposited by a process for deposition of electrically charged particles previously put into suspension in a liquid medium onto a surface of a conducting substrate, displacement of particles towards the surface of the substrate being generated by application of an electric field between two electrodes placed in the suspension, one of the electrodes forming the conducting substrate on which the deposit is made, the other electrode (counter electrode) being located in the liquid phase. A compact deposit of particles thus forms on the substrate if the zeta potential has an appropriate value as will be explained below. In the context of this document, the particle size refers to its largest dimension. Thus, a “nanoparticle” is a particle for which at least one of its dimensions is smaller than 100 nm. The “particle size” or “average particle size” of a powder or a set of particles is given by D50. The “zeta potential” of a suspension is defined as being the difference in potential between the heart of the solution and the shear plane of the particle. It is representative of the stability of a suspension. The shear plane (or hydrodynamic radius) corresponds to an imaginary sphere around the particle in which the solvent moves with the particle when the particles move in the solution. The theoretical basis and the determination of the zeta 16 potential are known to the electrochemist who develops depositions by electrophoresis; it can be deduced from the electrophoretic mobility. There are several marketed techniques and devices for making a direct measurement of the zeta potential. When the dry extract is small, the zeta potential can be measured using a Zetasizer Nano ZS type equipment made by the Malvern Company. This equipment uses optical devices to measure particle displacement speeds as a function of the electric field applied to them. The solution also has to be highly diluted to enable the passage of light. When the quantity of dry extract is large, the zeta potential can be measured using acoustophoresis techniques, for example using a device called “acoustosizer” made by the Colloidal Dynamics Company. The particle speed is then measured by acoustic techniques. “Dispersant” refers to a compound capable of stabilizing the colloidal suspension and particularly preventing particles from agglomerating. The process according to the invention comprises essential electrophoretic deposition steps of particles of cathode, anode and solid electrolyte materials. Such a process can significantly reduce the quantity of defects in films obtained in comparison with quantities obtained with known processes, particularly large pores, cavities, crazing and clusters; the quality of deposited films is better when the suspension from which the deposition is made is sufficiently stable. The process according to the invention can be used to deposit thin films of electrodes and/or electrolyte. The thickness of these films is usually less than about 20 μm, preferably less than about 10 μm, and even more preferably less than 5 μm. The process for fabrication of all-solid-state thin film batteries according to this invention has an advantageous alternative to known techniques and particularly to PVD deposition techniques, in that it can be used to make very dense depositions at low temperature on large substrate areas with high deposition rates, easily and very precisely controllable thicknesses (depending on the size of the particles) over a wide thickness range varying from a tenth of a micron to several tens or even hundreds of microns without requiring very expensive investment in complex and not very productive machines. Figures 1a to 1c show the differences between intra-agglomerate porosity 3 between particles 2 that will be referred to in this document as “pores”, and inter-cluster porosity 6 between clusters 5 and will be referred to as “cavities” 6. A compact deposit is a deposit without any cavities or cracks. On the other hand, it does have porosity in a ratio expressed as a percentage and calculated as follows: Porosity [%] = [(density of the solid-state material – real density)/real density] x 100 17 knowing that the "real density" is the density measured on the deposited film and the density of the solid-state material is the solid density of the deposited material, ignoring the presence of particles that create porosity when stacked. The following describes each step in the process according to the invention. Preparation of suspensions Deposition is preferably done from very stable SP+, SP-, SPn colloidal suspensions so as to obtain a deposit with a perfectly uniform thickness with no roughness, few defects and as compact as possible after the electrophoretic deposition process. The stability of suspensions depends on the size of the P+, P-, Pn, particles and the nature of the solvent used and the stabilizer that was used to stabilize the colloidal suspension. Procurement of these colloidal suspensions corresponds to steps (a), (b) and (c) in a main embodiment of the process according to the invention. “SP+” refers to a colloidal suspension of “P+” particles containing materials used to obtain a cathode film, “SP-” refers to a colloidal suspension containing P- particles of materials used to obtain an anode film, “SPn” refers to a colloidal suspension of “Pn” particles of materials used to obtain an electrolyte film. Colloidal suspensions containing nanometric sized particles are preferred to facilitate subsequent consolidation of the deposit if necessary and to assure that thin film deposits can be made with very precise thicknesses and profiles (roughness). The average size D50 of these particles is preferably less than 100 nm, and more preferably (especially in the case in which the suspension comprises particles of materials with high melting points) less than 30 nm. Consolidation of a deposit with small particles is much facilitated if the deposit is compact. Making electrophoretic depositions from stable colloidal suspensions avoids the formation of pores, cavities and clusters that are prejudicial to consolidation of the deposit. Furthermore with this technique, it is possible to have deposits with excellent compactness without necessarily making use of mechanical pressing, regardless of the size of the deposited particles. The stability of suspensions can be expressed by their zeta potential. In the context of this invention, the suspension is considered to be stable when its zeta potential is greater than 40 mV, and very stable when it is greater than 60 mV. On the other hand, particle clusters can develop when the zeta potential is less than 20 mV. Thus, in some embodiments, depositions are done from colloidal suspensions with a zeta potential of more than 40 mV, and even more preferably 60 mV (absolute value) to guarantee good compactness of the thin film. However, in other preferred embodiments of this invention, the suspensions have 18 a small dry extract of particles and the zeta potential is less than 40 mV, as is described in more detail below. Colloidal suspensions that will be used in electrophoresis comprise an electric insulating solvent that may be an organic solvent, or demineralized water, or a mix of solvents, and particles to be deposited. In a stable suspension, the particles do not agglomerate with each other to create clusters that could induce cavities, clusters and/or important defects in the deposit. Particles remain isolated in the suspension. Also in one embodiment of this invention, the stability of the suspension necessary to obtain a compact deposit is obtained through the addition of stabilizers. The stabilizer avoids flocculation of powders and the formation of clusters. It can act electrostatically or sterically. Electrostatic stabilization is based on electrostatic interactions between charges and is obtained by the distribution of charged species (ions) in the solution. Electrostatic stabilization is controlled by the surface charge of particles; consequently, it may depend on the pH. Steric stabilization uses non-ionic surfactant polymers or even proteins which, when added to the suspension, are absorbed at the surface of particles to cause repulsion by congestion of the inter-particle space. A combination of the two stabilization mechanisms is also possible. Electrostatic stabilization is preferred for the purposes of this invention because it is easy to implement, reversible, inexpensive and facilitates subsequent consolidation processes. However, the inventors have observed that with nanoparticles of the battery materials used for this invention, stable colloidal suspensions of particles that do not agglomerate among themselves and/or of clusters of a few particles can be obtained, without any addition of stabilizers. Particles and/or clusters are preferably smaller than 100 nm, and even more preferably smaller than 50 nm. These suspensions were obtained for low quantities of dry extracts between 2 g/L and 20 g/L, preferably between 3 and 10 g/L, and more particularly for dry extracts of the order of 4g/l, in alcohol and acetone. These stable colloidal suspensions of particles without added stabilizers are especially preferred for this invention. The Zeta potential of such suspensions is usually less than 40 mV, and more particularly between 25 and 40 mV. This could mean that such suspensions tend to be instable, however the inventors have observed that the use of such suspensions for an electrophoretic deposition leads to very good quality deposited films. With this type of suspension, the nanoparticles are negatively charged, therefore they are compatible with anaphoretic depositions. The addition of stabilizers or cations to the 19 suspension to modify the surface charge of nanoparticles to make them compatible with cataphoretic polarizations could lead to deposits being polluted. Organic stabilizers with low volatility could electrically isolate the nanoparticles thus preventing any electrochemical response. Deposition voltages of less than 5 V must be preferred when the solvent used is water. At above 5 V, water can be electrolyzed causing gas production on electrodes that make deposits porous and reduce their adherence onto the substrate. Galvanic reactions in an aqueous medium also cause the formation of metal cations that can pollute deposits. In one preferred embodiment, depositions are made in a solvented phase. It is thus possible to work at much higher voltages, thus increasing deposition rates. According to the invention, nanoparticles used for making the cathode thin film are preferably but not exhaustively chosen from among one or several of the following Mx materials: (i) LiMn2O4, LiCoO2, LiNiO2, LiMn1,5Ni0,5O4, LiMn1,5Ni0,5-xXxO4 oxides (where x is selected from among Al, Fe, Cr, Co, Rh, Nd, other rare earths and in which 0 < x < 0.1), LiFeO2, LiMn1/3Ni1/3Co1/3O4; (ii) LiFePO4, LiMnPO4, LiCoPO4, LiNiPO4, Li3V2(PO4)3 phosphates; (iii) all lithiated forms of the following chalcogenides: V2O5, V3O8, TiS2, TiOySz, WOySz, CuS, CuS2. According to the invention, the nanoparticles used for making the anode thin film are preferably but not exhaustively chosen from among one or several of the following materials: (i) tin oxinitrides (typical formula SnOxNy); (ii) mixed silicon and tin oxinitrides (typical formula SiaSnbOyNz where a>0, b>0, a+b2, 00, b>0, a+b2, 00, b>0, a+b2, 00, b>0, a+b2, 0