Method for manufacturing porous electrodes, and microbatteries containing such electrodes

Abstract

1. A method for producing an electrode having a porosity comprised between 20% and 60% by volume and pores with an average diameter of less than 50 nm, the method comprising: (a) The substrate and the primary mean diameter D between 2 nm and 100 nm 50 and a colloidal suspension containing aggregates or agglomerates of monodisperse primary nanoparticles of an electrode active material, the aggregates or agglomerates having an average diameter D between 50 nm and 300 nm. 50 and (b) depositing a layer from said colloidal suspension onto said substrate by a technique selected from the group consisting of electrophoresis, printing techniques, and coating techniques; (c) drying the layer obtained in step (b) and solidifying it by applying pressure and / or heat to obtain a mesoporous layer; (d) depositing a coating of electronically conductive material on and within the pores of said porous layer; This porous electrode can be used in lithium-ion microbatteries.

Description

[Technical Field]

[0001] This invention relates to the field of electrochemistry, and more specifically to thin-layer electrochemical systems. More specifically, it relates to electrodes that can be used in electrochemical systems such as lithium-ion microbatteries. This invention applies to negative and positive electrodes. It relates to porous electrodes that can be impregnated with a liquid phase or a solid electrolyte that does not contain a liquid electrolyte.

[0002] The present invention also relates to a method for preparing such porous electrodes by applying nanoparticles of electrode material, and to electrodes obtained in this manner. Furthermore, the present invention relates to a method for manufacturing a lithium-ion microbattery comprising at least one of these electrodes, and to microbatteries obtained in this manner. [Background technology]

[0003] Lithium-ion batteries have the best energy density among the various electrochemical energy storage technologies on the market. Various architectures and electrode chemical compositions exist for fabricating these batteries. Methods for manufacturing lithium-ion batteries are presented in numerous articles and patents, and are listed in the book "Advances in Lithium-ion batteries" edited by W. van Schalkwijk and B. Scrosati, Kluever Academic / Plenum Publishers, 2002.

[0004] There is a growing demand for micro-batteries, or extremely small rechargeable batteries, that can be embedded in electronic cards. These electronic circuits can be used in many applications, such as secure transaction cards, electronic labels, implantable medical devices, and various micromachine systems.

[0005] In prior art, electrodes for lithium-ion batteries can be manufactured using coating techniques, particularly by roll coating, doctor blade coating, tape casting coating, and slot die coating. These methods deposit an ink consisting of active material particles in powder form onto a substrate surface. The particles constituting this powder typically have an average particle size of 5 μm to 15 μm.

[0006] These technologies allow for the fabrication of layers with thicknesses ranging from approximately 50 μm to 400 μm. The output and energy of the battery can be varied by adjusting the layer thickness, porosity, and the size of the active particles that comprise it.

[0007] The ink (or paste) deposited to form the electrode contains active material particles, as well as an (organic) binder, carbon powder that ensures electrical contact between particles, and a solvent that evaporates during the electrode drying step. A calendering step is performed on the electrode to improve the quality of electrical contact between particles and to densify the deposited layer. After this compression step, the active particles of the electrode occupy approximately 60% of the volume of the deposit, which means that there is typically about 40% porosity between the particles.

[0008] To effectively optimize the volumetric energy density of lithium-ion microbatteries manufactured using conventional methods, it can be extremely useful to reduce the porosity of the electrodes and increase the amount of active ingredient per unit volume of the electrodes. This can be done by many methods.

[0009] In extreme cases, a non-porous, sufficiently dense layer can be used to maximize the volumetric energy density of the electrode. Such a dense layer can be fabricated using vacuum deposition techniques, for example, by physical vapor deposition (PVD). However, since this non-porous layer (called the all-solid layer) cannot contain liquid electrolytes that promote ion transport or electron-conductive fillers that promote charge transport, its thickness in the battery must be kept to a few micrometers, otherwise it would become too resistant.

[0010] Furthermore, it is possible to optimize conventional ink technology to increase the density of the layer obtained after calendering. It has been shown that a layer density of 70% can be achieved by optimizing the size distribution of the deposited particles (see Non-Patent Literature 1). An electrode with 30% porosity, containing a conductive filler and impregnated with a lithium-ion conductive electrolyte can be estimated to have a higher volumetric energy density of approximately 35% compared to the same electrode with 50% porosity consisting of monodisperse particles. Moreover, by impregnating with a highly ionic conductive phase and adding an electron conductor, the thickness of this electrode can be increased significantly compared to that made possible by vacuum deposition techniques, which result in a denser but more resistant layer. This increase in electrode thickness increases the energy density of the resulting battery cell.

[0011] However, while such a size distribution of active material particles increases the energy density of the electrode, it is not without its problems. Particles of varying sizes in the electrode can have varying capacities. Under the influence of the same charging and / or discharging current, they can be locally charged and / or discharged to a greater or lesser extent depending on their size. When the battery is no longer receiving current, the local charge state between the particles can be re-equalized, but in a transient phase, local imbalances can cause local stress on the particles outside their stable voltage range. This local charge imbalance can become even more apparent at high current densities. Consequently, this imbalance leads to loss of cycle performance, safety risks, and output limitations of the battery cell. The same is true when the electrode is heterogeneous, i.e., has porosity with varying sizes, and this heterogeneity contributes to making wetting of the electrode pores more difficult.

[0012] The effect of the particle size distribution of these active material particles on the current / voltage relationship of the electrodes was studied by numerical simulation in Non-Patent Literature 2. In the prior art, active material particles with sizes typically between 5 μm and 15 μm are used in the aforementioned electrodes for ink technology. Contact between each particle is substantially point-like, and the particles are bound together with an organic binder, often polyvinylidene fluoride (abbreviated as PVDF).

[0013] A binder-free mesoporous electrode layer for lithium-ion batteries can be deposited by electrophoresis. This is known from Patent Document 1 (I-TEN). Although it can be impregnated with a liquid electrolyte, its electrical resistivity remains extremely high.

[0014] The liquid electrolyte used for impregnating porous electrodes consists of an aprotic solvent containing a dissolved lithium salt. This is highly flammable and can cause the battery cell to burn violently, especially when the cathode active material is outside its stable voltage range or when hot spots appear locally in the battery cell.

[0015] To find solutions to the safety issues specific to the structure of this lithium-ion battery cell, we can take an approach along three axes.

[0016] According to the first axis, organic solvent-based electrolytes can be replaced with ionic liquids that have extremely high temperature stability. However, ionic liquids do not wet the surface of organic materials, and the presence of PVDF and other organic binders in conventional lithium-ion battery electrodes means that the fixed electrodes are not wetted by this type of electrolyte, affecting electrode performance. Ceramic separators have been developed to overcome this problem at the electrolyte boundary between electrodes, but the fact remains that the presence of organic binders on the electrodes continues to cause problems with the use of ionic liquid-based electrolytes.

[0017] According to the second axis, to prevent local imbalances in charge states that can cause localized stress on the active material outside its operating voltage range during intense discharge, homogenization of particle size may be sought. However, this optimization may come at the expense of the cell's energy density.

[0018] According to the third axis, the distribution and distribution of conductive filler (usually carbon black) can be homogenized at the electrodes to prevent localized areas of higher electrical resistance that could lead to the formation of hot spots during battery output operation.

[0019] More specifically, regarding the manufacturing method of battery electrodes in the prior art, the manufacturing cost is determined in part by the properties of the solvent and ink used. The cost of manufacturing the electrodes substantially arises from the complexity of the ink used (binder, solvent, carbon black) in addition to the cost of the active material itself. The main solvent used in the fabrication of lithium-ion battery electrodes is N-methyl-2-pyrrolidone (abbreviated as NMP). NMP is an excellent solvent for dissolving PVDF, which functions as a binder in the ink formulation.

[0020] Drying NMP contained in electrodes presents a significant economic challenge. The extremely low vapor pressure and high boiling temperature of NMP make drying difficult in industrial environments. Solvent vapors must be recovered and reprocessed. Furthermore, to ensure better and more reliable electrode adhesion to the substrate, the drying temperature of NMP must not be excessively high; this also tends to increase drying time and costs. This is described in Non-Patent Document 3.

[0021] Other less expensive solvents, particularly water and ethanol, can be used to prepare the ink. However, their surface tension is greater than that of NMP, so they do not wet the surface of the metal current collector very well. Furthermore, particles, especially carbon black nanoparticles, tend to aggregate in water. These aggregations result in an uneven distribution of components that enter the electrode composition (binder, carbon black, etc.). Moreover, even with water or ethanol, trace amounts of water may remain adsorbed on the surface of the active material particles even after drying.

[0022] Finally, in addition to the issue of ink formulations for obtaining low-cost and efficient electrodes, it should be noted that the ratio of the electrode's energy density to its power density can be adjusted according to the particle size of the active material, and indirectly according to the porosity and thickness of the electrode layer. An article by J. Newman (Non-Patent Literature 4) shows the effects of electrode thickness and its porosity on discharge rate (power) and energy density, respectively. [Prior art documents] [Patent Documents]

[0023] [Patent Document 1] International Publication No. 2019 / 215407 [Non-patent literature]

[0024] [Non-Patent Document 1] J.Ma and LCLim, "Effect of particle size distribution of sintering of agglomerate-free submicron alumina powder compacts", J.Europ.Ceramic Soc., 2002, 22(13), p.2197-2208 [Non-Patent Document 2] ST Taleghani et al., “A study on the Effect of Porosity and Particle Size Distribution On Li-Ion Battery Performance”, j.Electrochem.Soc., 2017, 164(11), p.E3179-E3189 [Non-Patent Document 3] DL Wood et al., “Technical and economic analysis of solvent-based lithium-ion electrode drying with water and NMP,” Drying Technology, 2018, Volume 36, No. 2 [Non-Patent Document 4] J. Newman, "Optimization of Porosity and Thickness of a Battery Electrode by Means of a Reaction-Zone Model", J.Electrochem.Soc., 1995, 142(1), p.97-101 [Overview of the project] [Problems that the invention aims to solve]

[0025] The problem that this invention aims to overcome is to provide a new electrode for lithium-ion microbatteries that has excellent cycle life, improved safety, and extremely high energy density combined with extremely high power density. [Means for solving the problem]

[0026] More specifically, to overcome this safety issue inherent in the structure of conventional lithium-ion battery cells, the inventors followed three guidelines.

[0027] According to the first guideline, organic solvent-based electrolytes should be replaced with a mixture of organic solvent and ionic liquid, or an ionic liquid, that has extremely high temperature stability. However, ionic liquids do not wet the surface of organic materials, and the presence of PVDF and other organic binders in conventional battery electrodes prevents this type of electrolyte from wetting the electrodes, affecting electrode performance. Although ceramic separators have been developed to overcome this problem at the electrolyte boundary between electrodes, the fact remains that the presence of organic binders in the electrodes continues to cause problems with the use of ionic liquid-based electrolytes.

[0028] According to the second guideline, in order to prevent local imbalances in charge states that can cause localized stress on the active material outside its conventional operating voltage range during violent discharge, efforts should be made to homogenize the particle size.

[0029] According to the third guideline, in order to avoid localized areas of greater electrical resistance that could lead to the formation of hot spots during battery output operation, efforts should be made to homogenize the distribution and allocation of conductive additives ("conductive fillers," only carbon black is actually used) in the electrodes.

[0030] In the present invention, this problem is solved by a lithium-ion microbattery electrode that is entirely ceramic, mesoporous, free of organic binders, has a porosity between 50% and 25%, and whose channel and pore sizes are homogeneous to ensure good dynamic equilibrium of the cell.

[0031] This all-solid mesoporous structure, free of organic components, is obtained by depositing aggregates and / or assemblies of active material nanoparticles onto a substrate. The primary particles constituting these aggregates and / or assemblies are in the range of nanometers or tens of nanometers in size, and each aggregate and / or assembly contains at least four primary particles.

[0032] In the first embodiment, the substrate can be a substrate capable of functioning as an electrostatic current collector, or in the second embodiment, it can be a temporary intermediate substrate, which will be described in more detail below.

[0033] The deposition thickness can be increased by using aggregates with diameters of tens or even hundreds of nanometers, rather than unaggregated primary particles, each having a size in the range of nanometers or tens of nanometers. These aggregates must have a size of less than 300 nm. Continuous mesoporous films cannot be obtained from sintering aggregates larger than 500 nm. In this case, two different sizes of porosity are observed in the deposit: porosity between aggregates and porosity within the aggregates.

[0034] In fact, when drying a deposit of nanoparticles on a substrate capable of functioning as an electrostatic collector, cracking is observed in the layer. This cracking appears to be substantially dependent on the particle size, the density of the deposit, and its thickness. The critical thickness for this cracking is defined by the following relationship: h max =0.41[(GMΦ rcp R 3 ) / 2γ] In the formula, h max Φ is the critical thickness, g is the shear modulus (shear module) of the nanoparticle, M is the coordination number, and Φ is the critical thickness. rcp θ represents the volume fraction of the nanoparticles, R is the particle radius, and γ is the interfacial tension between the solvent and air.

[0035] The use of mesoporous aggregates consisting of primary nanoparticles at least 10 times smaller than the aggregate size can substantially increase the critical thickness at which cracking occurs in the layer. Similarly, to improve wetting and deposition adhesion and reduce the risk of cracking, it is possible to add a few percent of a solvent with lower surface tension (such as isopropyl alcohol (abbreviated as IPA)) to water or ethanol. Binders and dispersants can be added to increase the deposition thickness while suppressing or eliminating cracking. These additives and organic solvents can be removed during or before the sintering process by heat treatment in air, such as debinding.

[0036] Furthermore, with primary particles of the same size, the size of the aggregates can be altered during their synthesis by precipitation by adjusting the amount of ligand (e.g., polyvinylpyrrolidone, abbreviated as PVP) in the synthesis reactor. Therefore, to maximize the density in the deposition of aggregates, it is possible to create inks containing aggregates of extremely varying sizes or two complementary sizes. Unlike the sintering of non-aggregated nanoparticles, the sintering state between aggregates of different sizes does not change. These are primary nanoparticles that constitute aggregates that can associate together. These primary nanoparticles have the same size regardless of the size of the aggregates. The size distribution of aggregates improves the density in deposition and increases the contact points between nanoparticles, but does not change the solidification temperature.

[0037] However, the aggregates must be kept small so that a continuous mesoporous film can be formed during the heat treatment of the layer. If the aggregates are too large, this will hinder their sintering, and the formation of two distinct types of porosity will be observed in the layer: porosity between the aggregates and porosity within the aggregates themselves.

[0038] After partial sintering, a porous, preferably mesoporous, layer or plate is obtained without carbon black or an organic binder, and all nanoparticles associate together (by the known necking phenomenon) to form a continuous mesoporous network characterized by unimodal porosity. The resulting porous, preferably mesoporous layer is entirely solid and ceramic. There is no risk of loss of any electrical contact between active material particles during cycling, which increases the potential to improve the battery's cycle performance. Furthermore, after sintering, the porous, preferably mesoporous layer adheres well to the metal substrate to which it is deposited or transferred (in the case of initial deposition on an intermediate substrate).

[0039] The high-temperature heat treatment performed to sinter the nanoparticles together thoroughly dries the electrodes and removes all trace amounts of water, solvent, or other organic additives (stabilizers, binders) adsorbed on the surface of the active material particles. A low-temperature heat treatment (de-bindering treatment) can be performed before the high-temperature heat treatment (sintering) to dry the placed or deposited electrodes and remove any trace amounts of water, solvent, or other organic additives (stabilizers, binders) adsorbed on the surface of the active material particles. This de-bindering treatment can be performed in an oxidizing atmosphere.

[0040] The final electrode porosity can be adjusted depending on the sintering time and temperature. Depending on the energy density requirements, the latter can be adjusted to a porosity range between 50% and 25%.

[0041] In all cases, the power density of the electrodes thus obtained is kept extremely high by the mesoporous structure. Furthermore, regardless of the size of the mesopores in the active material (it is known that after sintering, the concept of nanoparticles is not the same as that of the material having a three-dimensional structure including a network of channels and mesopores), dynamic cell equilibrium is well maintained, which is useful for maximizing power density and battery cell life.

[0042] The electrodes in this invention have a high specific surface area that reduces the ionic resistance of the electrodes. However, in order for these electrodes to supply maximum output, they still need to have very good electronic conductivity to prevent resistance losses in the battery. Improving the electronic conductivity in this cell becomes even more important as the electrode thickness increases. Furthermore, this electronic conductivity needs to be sufficiently homogeneous across the electrodes to prevent the localization of hot spots.

[0043] In this invention, an electronically conductive material coating is deposited in and within the pores of a porous layer. This electronically conductive material can be deposited by atomic layer deposition (ALD) or from a liquid precursor. The electronically conductive material can be carbon.

[0044] To deposit a carbon layer from a liquid precursor, the mesoporous layer can be immersed in a solution with a high carbon precursor content (for example, a carbohydrate solution such as sucrose). The electrode is then dried and heat-treated in nitrogen at a temperature sufficient to decompose the carbon precursor. This forms an extremely thin, well-dispersed carbon coating across the entire inner surface of the electrode. This coating provides the electrode with good electronic conductivity, regardless of its thickness. It should be noted that this treatment is possible after sintering, as the electrode is entirely solid, free of organic residues, and can withstand thermal cycling through various heat treatments.

[0045] A first object of the present invention is a method for manufacturing a porous electrode, particularly for electrochemical devices, wherein the electrode comprises a porous layer deposited on a substrate, the layer is binder-free, has a porosity between 20% and 60% by volume, preferably between 25% and 50% by volume, and has pores with an average diameter of less than 50 nm, and the manufacturing method is as follows: (a) A substrate and a colloidal suspension or paste containing an aggregate or agglomerate of monodisperse primary nanoparticles of at least one electrode active material P, wherein the above-mentioned monodisperse primary nanoparticles are included within the range of 2 nm to 150 nm (preferably within the range of 2 nm to 100 nm, preferably within the range of 2 nm to 60 nm, and even more preferably within the range of 2 nm to 50 nm) and have an average primary diameter D 50 and the above-mentioned aggregate or agglomerate has an average diameter D included within the range of 50 nm to 300 nm (preferably within the range of 100 nm to 200 nm), and preparing a colloidal suspension or paste 50 (b) From the above-mentioned colloidal suspension or paste prepared in step (a), depositing a layer on at least one surface of the above-mentioned substrate by a method selected from the group consisting of electrophoresis, printing, particularly inkjet printing or flexographic printing, coating, preferably coating using a doctor blade, i.e., doctor blade coating, roll coating, curtain coating, dip coating, or slot die coating (c) If appropriate, drying the above-mentioned layer obtained in step (b), either before or after separating the above-mentioned layer from its intermediate substrate, and then optionally heat-treating the above-mentioned dried layer, preferably in an oxidizing atmosphere, and solidifying it by pressurization and / or heating to obtain a porous layer, preferably a mesoporous layer (d) Depositing a coating of an electronically conductive material in the pores of the porous layer and within the pores, characterized by the steps of The above-mentioned substrate can be a substrate that can function as an electrical current collector or an intermediate substrate Preferably, after step (d), in order to enhance the battery life and its performance, the obtained electrode can be coated with an ion-conducting layer. The ion-conducting layer can be Li

[0046] Al 1.3 Al 0.3 Ti 1.7 (PO4)3, nafion (registered trademark), Li3BO3, PEO, or a mixture of PEO and a lithium-ion carrying phase such as a lithium salt

[0047] In step (b), deposition can be carried out on one or both sides of the substrate.

[0048] Advantageously, when the substrate described above is an intermediate substrate, the layer described above is separated from the intermediate substrate in step (c) and, after solidification, a porous plate is formed. This separation step can be performed before or after drying the layer obtained in step (b).

[0049] Advantageously, when the above-mentioned substrate is an intermediate substrate, after step (c) and before step (d), an electrically conductive sheet is prepared, covered on at least one surface, preferably two of its surfaces, with a thin layer of conductive adhesive or a thin layer of nanoparticles of at least one electrode active material P; and then at least one porous plate is bonded to one surface of the electrically conductive sheet, preferably each surface, to obtain a porous layer, preferably a mesoporous layer, on a substrate capable of functioning as a current collector.

[0050] Advantageously, if the colloidal suspension or paste prepared in step (a) contains organic additives, such as ligands, stabilizers, binders, or residual organic solvents, the dried layer in step (c) is heat-treated, preferably in an oxidizing atmosphere. This heat treatment enables de-binding and can be performed simultaneously with the solidification (sintering) in step (c) under an oxidizing atmosphere, or before the step of solidifying the dried layer.

[0051] In the first embodiment, the substrate described above is a substrate capable of functioning as an electrostatic current collector. Its chemical properties must be suitable for the temperature of the heat treatment in step (c) in the method for manufacturing the porous electrode (debindering and / or sintering heat treatment), and in particular, it must not melt, form an oxide layer which may have excessively high electrical resistance, or react with the electrode material. Advantageously, a metal substrate can be selected, which can be made from tungsten, molybdenum, chromium, titanium, tantalum, stainless steel, or an alloy of two or more of these materials. Such metal substrates are extremely expensive and can significantly increase the cost of the battery. Alternatively, this metal substrate can be coated with a conductive or semiconductor oxide before depositing a layer of material P. The thickness of the layer after step (c) is advantageously between about 1 μm and about 300 μm, preferably between 1 μm and 150 μm, more preferably between 10 μm and 50 μm, or between 10 μm and 30 μm. When the substrate used is capable of functioning as an electrostatic current collector, the thickness of the layer after step (c) is limited to prevent any cracking problems.

[0052] In the second embodiment, the substrate described above is a temporary intermediate substrate, such as a flexible substrate which may be a polymer film. In this second embodiment, the deposition step is advantageously performed on one side of the intermediate substrate so that the subsequent layer can be easily separated from the intermediate substrate. In this second embodiment, the layer can be separated from the substrate after drying, preferably before heating, but no later than the end of step (c). The thickness of the layer after step (c) is advantageously 5 mm or less, and advantageously between about 1 μm and about 500 μm. The thickness of the layer after step (c) is advantageously less than 300 μm, preferably between about 5 μm and about 300 μm, and preferably between 5 μm and 150 μm.

[0053] Advantageously, the porous layer obtained at the end of step (c) is 10 m 2 / g~500m 2 It has a specific surface area within the range of / g. Its thickness is advantageously between 1 and 500 μm, and preferably between 4 and 400 μm.

[0054] The size distribution of primary particles of the active material P is preferably narrow. In a preferred method, the aggregates described above preferably contain at least three primary particles. The size distribution of the aggregates described above is preferably polydisperse. In one embodiment, the size distribution of the aggregates is bimodal, i.e., has two size distribution peaks, which are called D1 and D2, where D1 > D2, and the D2 / D1 ratio can be, for example, between 3 and 7, preferably between 4 and 6. This prevents the formation of large voids and ensures good density of the mesoporous layer.

[0055] The nanoparticle suspension can be prepared in water or ethanol, or in a mixture of water and ethanol, or in a mixture of ethanol and isopropyl alcohol (less than 3% isopropyl alcohol). This suspension does not contain carbon black.

[0056] To use coating techniques such as roll coating, curtain coating, slot die coating, or dip coating, the suspension used is advantageously characterized by at least 15%, preferably at least 50%, of dry extract.

[0057] The deposition of the aforementioned coating of electronically conductive material can be carried out by atomic layer deposition (ALD) technology, or by immersing a porous layer in a liquid phase containing a precursor of the electronically conductive material, and then converting the precursor into the electronically conductive material.

[0058] The aforementioned precursor is advantageously a high-carbon compound, such as a carbohydrate, preferably a polysaccharide, and the above-mentioned conversion to an electronically conductive material is, in this case, preferably carried out by thermal decomposition under an inert atmosphere (e.g., nitrogen). The above-mentioned electronically conductive material can be carbon, which can be deposited particularly by ALD or by immersion in a liquid phase containing a carbon precursor.

[0059] In the second embodiment described above, the method for manufacturing the porous electrode of the battery involves using a polymer intermediate substrate (such as PET) to obtain a tape called a "raw tape." This tape is then separated from the substrate to form a plate or sheet (hereinafter, the term "plate" will be used regardless of its thickness). After cutting this plate, it can be separated from the intermediate substrate. The plate is then calcined to remove organic components. The plate is then sintered to solidify the nanoparticles until a mesoporous ceramic structure with a porosity between 25% and 50% is obtained. The porous plate obtained in step (c) has a thickness of 5 mm or less, preferably between about 1 μm and about 500 μm. The thickness of the layer after step (c) is preferably less than 300 μm, preferably between about 5 μm and about 300 μm, preferably between 5 μm and 150 μm. Subsequently, a coating of an electronically conductive material is deposited in and within the pores of the mesoporous porous layer or porous plate, as described above.

[0060] In this second embodiment, an electrically conductive sheet is also prepared, which is preferably covered on both sides with an intermediate thin layer of nanoparticles identical to those constituting the electrode plate, or covered on both sides with a thin layer of conductive adhesive. The aforementioned thin layer preferably has a thickness of less than 1 μm. This sheet can be a metal strip or a graphite sheet.

[0061] This electrically conductive sheet is then placed between the two porous electrode plates obtained so far, and between the two porous plates obtained after step (c). The assembly is then hot-pressed to convert the aforementioned nanoparticle intermediate thin layer by sintering, solidifying the electrode / substrate / electrode assembly and the porous plate / substrate / porous plate assembly, respectively, to obtain a rigid, integrated subassembly. During this sintering, the junctions between the electrode layer and the intermediate layer, and between the porous plate and the intermediate layer, are obtained by atomic diffusion. This phenomenon is known as "diffusion bonding." The assembly is fabricated from two electrode plates and two porous plates of the same polarity (typically between two anodes or two cathodes), with the metal sheets between these two electrode plates and two porous plates of the same polarity connecting them in parallel.

[0062] One advantage of the second embodiment is the ability to use inexpensive substrates such as aluminum strips, copper, or graphite strips. In fact, since these strips do not withstand the heat treatment required to solidify the deposited layer, bonding them to the electrode plate after that heat treatment also helps prevent oxidation.

[0063] In other variations of the second embodiment, when obtaining a porous plate / substrate / porous plate assembly, it is advantageous thereafter, particularly when the porous plate used is thick, to deposit a coating of an electronically conductive material in and within the pores of the porous plate, preferably a mesoporous plate, of the porous plate / substrate / porous plate assembly, as described above.

[0064] The deposition of the aforementioned coating of electronically conductive material can be carried out by atomic layer deposition (ALD) technology, or by immersing a porous layer in a liquid phase containing a precursor of the electronically conductive material, and then converting the precursor into the electronically conductive material.

[0065] This "diffusion bonding" assembly can be made separately, as described earlier, and the resulting electrode / substrate / electrode subassembly can be used to manufacture a battery. Alternatively, this diffusion bonding assembly can be achieved by stacking and heat-pressing the entire battery structure, in which case a multilayer stack is assembled including a first porous anode layer, its metal substrate, a second porous anode layer, a solid electrolyte layer, a first cathode layer, its metal substrate, a second cathode layer, a new solid electrolyte layer, and so on.

[0066] More specifically, an electrode plate, which is a mesoporous ceramic, can be bonded to both surfaces of a metal substrate (in which case the same configuration as that obtained by depositing on both surfaces of the metal substrate can be found).

[0067] This electrode / substrate / electrode subassembly can then be obtained by bonding electrode plates to an electrically conductive sheet that can subsequently function as an electrostatic current collector, or by depositing layers on a substrate that can function as an electrostatic current collector, particularly a metal substrate, and then sintering it.

[0068] Regardless of the embodiment of the electrode / substrate / electrode subassembly, the electrolyte membrane (separator) is then deposited on the latter. Subsequently, the necessary cuts are made to fabricate a battery containing multiple basic cells, and then the subassemblies are stacked (typically in a "head-to-tail" mode), thermally compressed, and the electrodes are welded together in the solid electrolyte.

[0069] Alternatively, the necessary cuts for fabricating a battery containing multiple basic cells can be made before depositing the electrolyte membrane (separator) onto each electrode / substrate / electrode subassembly, after which the subassemblies are stacked (typically in a "head-to-tail" mode) and thermally compressed to weld the electrodes together in the electrolyte membrane (separator).

[0070] In the two modifications presented earlier, thermal compression welding is performed at a relatively low temperature, which is possible because the nanoparticles are extremely small. As a result, no oxidation of the metal layer of the substrate is observed.

[0071] In other embodiments of the assemblies described below, a conductive adhesive (with graphite added), or a sol-gel type deposition with conductive particles added, or preferably a metal (e.g., aluminum) strip having a low melting point, can be used to weld the plates together by deforming the metal strip by creep during thermomechanical (hot pressing) treatment.

[0072] When electrodes need to be used in a battery, an active material P that is dimensionally stable during charge and discharge cycles is preferably selected. This can be particularly selected from the group consisting of the following: LiMn2O4 oxide, Li 1+x Mn 2-x O4 (in the formula, 0 <x<0.15)、LiCoO2、LiNiO2、LiMn 1.5 Ni 0.5 O4, LiMn 1.5 Ni 0.5-x X x O4 (wherein X is selected from Al, Fe, Cr, Co, Rh, Nd, and other rare earth elements, such as Sc, Y, Lu, La, Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, 0 <x<0.1)、LiMn 2-x M x O4 (wherein M = Er, Dy, Gd, Tb, Yb, Al, Y, Ni, Co, Ti, Sn, As, Mg, or a mixture of these compounds, 0 <x<0.4)、LiFeO2、LiMn 1 / 3 Ni 1 / 3 Co 1 / 3 O2, LiLiLi 0.8 Co 0.15 Al 0.05 O2, Lial x Mn 2-x O4 (in the formula, 0≦x<0.15), LiNi 1 / x Co 1 / y Mn 1 / z O2 (where x+y+z=10) oLi x M yO2 (where 0.6 ≦ y ≦ 0.85 and 0 ≦ x + y ≦ 2, and M is selected from Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Sn, and Sb, or a mixture of these elements), Li 1.20 Nb 0.20 Mn 0.60 O2, oLi 1+x Nb y Me z A p O2 (where Me is at least one transition metal selected from Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Rf, Db, Sg, Bh, Hs, and Mt, and 0.6 < x < 1, 0 < y < 0.5, 0.25 ≦ z < 1, provided that A ≠ Me and A ≠ Nb and 0 ≦ p ≦ 0.2), oLi x Nb y-a N a M z-b P b O 2-c F c (where 1.2 < x ≦ 1.75, 0 ≦ y < 0.55, 0.1 < z < 1, 0 ≦ a < 0.5, 0 ≦ b < 1, 0 ≦ c < 0.8, and M, N, and P are each at least one element selected from the group consisting of Ti, Ta, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh, and Sb), oLi 1.25 Nb 0.25 Mn 0.50 O2, Li 1.3 Nb 0.3 Mn 0.40 O2, Li 1.3 Nb 0.3 Fe 0.40 O2, Li<0​​​​​​​​​​​​​​​​​​​​​0.2 Mn 0.6 O y (where 0.00 ≦ x ≦ 1.52, 1.07 ≦ y < 2.4), Li 1.2 Ni 0.2 Mn 0.6 O2, oLiNi x Co y Mn 1-x-y O2 (where 0 ≦ x, y ≦ 0.5), LiNi x Ce z Co y Mn 1-x-y O2 (where 0 ≦ x, y ≦ 0.5 and 0 ≦ z), o Lithium phosphates of LiFePO4, LiMnPO4, LiCoPO4, LiNiPO4, Li3V2(PO4)3, Li2MPO4F (where M = Fe, Co, Ni, or a mixture of various elements thereof), LiMPO4F (where M = V, Fe, T, or a mixture of various elements thereof), phosphates of the formula LiMM’PO4 (where M and M’ (M ≠ M’) are selected from Fe, Mn, Ni, Co, V, for example, LiFe x Co 1-x PO4 where 0 < x < 1), oFe 0.9 Co 0.1 OF type oxyfluorides, LiMSO4F (where M = Fe, Co, Ni, Mn, Zn, Mg), o The following chalcogenides, V2O5, V3O8, TiS2, titanium oxysulfide (TiO y S z (where z = 2 - y and 0.3 ≦ y ≦ 1), tungsten oxysulfide (WO y S z (where 0.6 < y < 3 and 0.1 < z < 2), all lithiated forms of CuS, CuS2, preferably Li x V2O5 (where 0 < x ≦ 2), Li x V3O8 (where 0 < x ≦ 1.7), Li x TiS2 (where 0 < x ≦ 1), lithium of titanium and lithium oxysulfide x TiO y S z (where z = 2 - y and 0.3 ≦ y ≦ 1 and 0 < x ≦ 1), Li xWO y S z (where z = 2 - y, 0.3 ≤ y ≤ 1, and 0 < x ≤ 1), Li x CuS (where 0 < x ≤ 1), Li x CuS2 (where 0 < x ≤ 1), can be particularly selected from the group consisting of.

[0073] By the porous layer in the present invention made from one of these materials, the cathode function of a battery, particularly a lithium-ion battery, can be ensured.

[0074] Also, the above-mentioned substance P can also be selected from the group consisting of. That is, oLi4Ti5O 12 , Li4Ti 5-x M x O 12 (where M = V, Zr, Hf, Nb, Ta, and 0 ≤ x ≤​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Each of these is at least one element selected from the group consisting of Nb, V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs, and Sn, and M 1 and M 2 They may be the same or different from each other, (0≦w≦5 and 0≦x≦1 and 0≦y≦2 and 0≦δ≦0.3), oLa x Ti 1-2x Nb 2+x O7 (in the formula, 0 <x<0.5)、 oM x Ti 1-2x Nb 2+x O 7±δ , In formula o, M is an element with an oxidation state of +III, more specifically, M is at least one element selected from the group consisting of Fe, Ga, Mo, Al, and B, and 0 <x≦0.20かつ-0.3≦δ≦0.3のもの、Ga 0.10 Ti 0.80 Nb 2.10 O7, Fe 0.10 Ti 0.80 Nb 2.10 O7, oM x Ti 2-2x Nb 10+x O 29±δ , In formula o, M is an element with an oxidation state of +III, more specifically, M is at least one element selected from the group consisting of Fe, Ga, Mo, Al, and B, and 0 <x≦0.40かつ-0.3≦δ≦0.3のもの、 oTi 1-x M 1 x Nb 2-y M 2 y O 7-z M 3 z or Li w Ti 1-x M 1 x Nb 2-y M 2 y O 7-z M 3z , oIn the formula, M 1 and M 2 Each of these is at least one element selected from the group consisting of Nb, V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs, and Sn. oM 1 and M 2 They may be the same, or they may be different from each other. oM 3 is at least one halogen, For o0≦w≦5 and 0≦x≦1 and 0≦y≦2 and z≦0.3, oTiNb2O 7-z M 3 z or Li w TiNb2O 7-z M 3 z However, M 3 is preferably at least one halogen selected from F, Cl, Br, I, or a mixture thereof, and 0 <z≦0.3、 oTi 1-x Ge x Nb 2-y M 1 y O 7±z Li w Ti 1-x Ge x Nb 2-y M 1 y O 7±z Ti 1-x Ce x Nb 2-y M 1 y O 7±z Li w Ti 1-x Ce x Nb 2-y M 1 y O 7±z , oIn the formula, M 1is at least one element selected from the group consisting of Nb, V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs, and Sn. For o0≦w≦5 and 0≦x≦1 and 0≦y≦2 and z≦0.3, oTi 1-x Ge x Nb 2-y M 1 y O 7-z M 2 z Li w Ti 1-x Ge x Nb 2-y M 1 y O 7-z M 2 z Ti 1-x Ce x Nb 2-y M 1 y O 7-z M 2 z Li w Ti 1-x Ce x Nb 2-y M 1 y O 7-z M 2 z , oIn the formula, M 1 and M 2 Each of these elements is at least one element selected from the group consisting of Nb, V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs, Ce, and Sn. oM 1 and M 2 They may be the same, or they may be different from each other. For o0≦w≦5 and 0≦x≦1 and 0≦y≦2 and z≦0.3, oTiO2, You can also choose from the group consisting of oLiSiTON.

[0075] The nanoparticles used in the present invention may have a core-shell type structure, in which case the above-mentioned substance P forms the core. The shell may or may not be an ion conductor, and may be a dielectric material.

[0076] The porous layer of this invention, fabricated from one of these materials, can ensure the anode function of a battery, particularly a lithium-ion battery. For use as an anode in a lithium-ion battery, an anode material with a lithium storage potential greater than 1V is advantageously used. This allows the battery to be charged extremely quickly.

[0077] The negative electrode can be made from titanate and / or mixed titanium oxide. Preferably, the electrode is impregnated with an ionic liquid containing a lithium salt. When the ionic liquid contains sulfur atoms, the substrate capable of functioning as an electrostatic collector is preferably a noble metal. Such a battery has the advantage of being able to operate at high temperatures.

[0078] Another object of the present invention is a porous electrode obtained by the method for producing a porous electrode according to the present invention. This porous electrode does not contain a binder. Its porosity is preferably between 20% and 60% by volume, and its average pore diameter is less than 50 nm. It may be intended to operate as a positive or negative electrode in an electrochemical device.

[0079] The electrodes of the present invention enable the fabrication of lithium-ion microbatteries having both high energy density and high power density. This performance is achieved as a result of limiting porosity (increasing energy density), extremely high specific surface area (advantageous for extremely small primary particles in the electrodes, leading to an increased exchange surface that reduces ion resistance), and the absence of organic binders (binders can locally hinder lithium access to the active material surface). A key feature of the present invention is the deposition of an electronically conductive material coating in and within the pores of the porous layer. This coating reduces the series resistance of the battery.

[0080] A further object of the present invention is the use of the method for manufacturing porous electrodes according to the present invention for manufacturing porous electrodes for lithium-ion batteries.

[0081] A further object of the present invention is to carry out the method for manufacturing a porous electrode according to the present invention for manufacturing a battery designed to have a capacity not exceeding 1 mAh, or a method for carrying out the porous electrode according to the present invention. The battery described above is advantageously a lithium-ion battery. In particular, this method for manufacturing a porous electrode can be applied to manufacture a cathode and / or an anode. This method for manufacturing a battery involves adding an electrolyte, preferably, to the porous electrode described above. o An electrolyte comprising at least one aprotic solvent and at least one lithium salt, o An electrolyte consisting of at least one ionic liquid and at least one lithium salt, o A mixture of at least one aprotic solvent, at least one ionic liquid, and at least one lithium salt, o A polymer made ion-conductive by adding at least one lithium salt, and The process may include the step of impregnating a lithium ion-supported phase, selected from the group consisting of a polymer phase or a mesoporous structure, with a polymer that has been made ion-conductive by adding a liquid electrolyte.

[0082] As described above, the electrodes of the present invention make it possible to fabricate lithium-ion batteries having both high energy density and high power density. Such batteries are also extremely reliable. There is no risk of loss of electrical contact between particles, which provides excellent cycle life. Furthermore, the current is well distributed in the electrodes, which is achieved by the homogeneity of pore size and local thickness in the active material, resulting in excellent homogeneity of electrical conductivity.

[0083] The battery in this invention can be designed and shaped to have a capacity of approximately 1 mAh or less (generally referred to as a "microbattery"). Typically, microbatteries are designed to be compatible with microelectronics manufacturing methods.

[0084] Therefore, the final object of the present invention is a lithium-ion microbattery obtained by the method for manufacturing a battery according to the present invention.

[0085] Figures 1 to 6 illustrate various aspects and embodiments of the present invention without limiting their scope. [Brief explanation of the drawing]

[0086] [Figure 1] Figure 1 shows the diffractogram of the primary nanoparticles used in the suspension before aggregate formation. [Figure 2] Figure 2 shows a photograph obtained by transmission electron microscopy observation of primary nanoparticles from the same sample as in Figure 1. [Figure 3] Figure 3 schematically shows the nanoparticles before heat treatment. [Figure 4] Figure 4 schematically shows nanoparticles after heat treatment and illustrates the phenomenon of "necking". [Figure 5] Figure 5 shows the change in the relative capacity of the battery in the present invention according to the number of charge and discharge cycles. [Figure 6] Figure 6 shows the charging curve of the same battery, where curve A corresponds to the charging state (right scale) and curve B corresponds to the absorbed current (left scale). [Modes for carrying out the invention]

[0087] (1.Definition) As part of this description, particle size is defined by its largest dimension. "Nanoparticle" means any particle or object of nanometer size, where at least one of its dimensions is less than 100 nm.

[0088] An "ionic liquid" is any liquid salt that can conduct electricity and differs from all molten salts by having a melting temperature below 100°C. Some of these salts remain liquid at room temperature and do not solidify even at extremely low temperatures. These salts are called "room temperature ionic liquids."

[0089] A “mesoporous” material refers to any solid having pores in its structure called “mesopores,” which have a size intermediate between the size of micropores (less than 2 nm wide) and the size of macropores (greater than 50 nm wide), that is, a size between 2 nm and 50 nm. This term corresponds to that adopted by IUPAC (International Union of Pure and Applied Chemistry), which is of reference to those skilled in the art. Therefore, the term “nanopore” is not used herein because, even if the mesopores defined above have nanoscale dimensions within the meaning of the definition of nanoparticles, it is known to those skilled in the art that pores smaller than the size of mesopores are called “micropores.”

[0090] The concept of porosity (and the term mentioned above) is presented in the article "Texture des materiaux pulverulents ou poreux" by F. Rouquercol et al., published on page 1050 of the "Techniques de l'Ingenieur" (Techniques of the Engineer) journal, in the section on analysis and characterization. This article also describes techniques for describing the characteristics of porous materials, particularly the BET method.

[0091] Within the scope of the present invention, "mesoporous electrode" or "mesoporous layer" means an electrode or layer having mesopores, respectively. As described below, in this electrode or layer, mesopores contribute significantly to the total pore volume. This is interpreted in the term "mesoporous electrode or layer with a mesopore porosity greater than X volume%" used in the following description.

[0092] The term "aggregate," according to the IUPAC definition, refers to a collection of weakly bound primary particles. In this case, these primary particles are nanoparticles with a diameter measurable by transmission electron microscopy. Aggregates of aggregated primary nanoparticles can usually be broken down (i.e., returned to primary nanoparticles) by techniques known to those skilled in the art, such as suspending the primary nanoparticles in a liquid phase under the influence of ultrasound.

[0093] According to the IUPAC definition, the term "aggregate" refers to a collection of strongly bound primary particles or aggregates.

[0094] The term "microbattery" is used herein to refer to batteries with a capacity not exceeding 1 mAh. Typically, microbatteries are designed to be compatible with microelectronics manufacturing methods.

[0095] (2. Preparation of Nanoparticle Suspension) The method for preparing porous electrodes described herein begins with a suspension of nanoparticles. It is preferable that this nanoparticle suspension is not prepared from dry nanopowder. They can be prepared by using sonication to pulverize the powder or nanopowder in a liquid phase and / or to deaggregate the nanoparticles.

[0096] In another embodiment of the present invention, nanoparticles are prepared directly in a suspension by precipitation. Synthesis of nanoparticles by precipitation yields primary nanoparticles that are extremely homogeneous in size, have a unimodal size distribution, i.e., an extremely narrow and monodisperse distribution, and possess good crystallinity and purity. Using these extremely homogeneous nanoparticles and their narrow distribution, controlled open porous structures can be obtained after deposition. The porous structures obtained after the deposition of these nanoparticles have few, preferably no, closed pores.

[0097] In a more preferred embodiment of the present invention, nanoparticles are directly prepared at their primary size by hydrothermal or solvothermal synthesis. This technique yields nanoparticles with an extremely narrow size distribution, which are called "monodisperse nanoparticles." The size of these unaggregated or unaggregated nanopowder / nanoparticles is called the primary size. This typically falls between 2 nm and 150 nm. It is advantageously between 10 nm and 50 nm, preferably between 10 nm and 30 nm. This facilitates the formation of an interconnected mesoporous network with electronic and ionic conductivity due to a phenomenon called "necking" in subsequent method steps.

[0098] In advantageous embodiments, the suspension of monodisperse nanoparticles can be carried out in the presence of a ligand or organic stabilizer to prevent aggregation or further aggregation of the nanoparticles. A binder may also be added to the nanoparticle suspension to facilitate the formation of deposits or raw tapes, particularly thick deposits without cracks.

[0099] In fact, in the context of the present invention, it has been found that it is preferable to start with a suspension of non-aggregated primary particles, and then induce or occur aggregation, rather than allowing aggregation of primary particles to occur spontaneously during the suspension preparation stage.

[0100] This monodisperse nanoparticle suspension can be purified to remove any potentially interfering ions. Depending on the degree of purification, it can then be specially treated to form aggregates or assemblies of controlled size. More specifically, the formation of aggregates or assemblies can result from the destabilization of the suspension, particularly by ions, by increasing the dry extract of the suspension, by altering the solvent of the suspension, or by adding destabilizers. The suspension is stable when sufficiently purified, and to destabilize it, ions are added, typically in the form of salts, where these ions are preferably lithium ions (preferably added in the form of LiOH).

[0101] If the suspension is not sufficiently purified, the formation of aggregates or assemblies can be carried out by spontaneous means or by aging alone. This method is simpler because it involves fewer purification steps, but it is more difficult to control the size of the aggregates or assemblies. One of the important aspects of electrode production in the present invention is based on appropriate control of the size of the primary particles of the electrode material and the degree of their aggregation or condensation.

[0102] If the stabilization of the nanoparticle suspension occurs after aggregate formation, the nanoparticles may remain in aggregate form. The resulting suspension can be used to prepare mesoporous deposits.

[0103] This suspension of nanoparticle aggregates or aggregates is then used to deposit a porous, preferably mesoporous, electrode layer according to the present invention by electrophoresis, inkjet printing, flexographic printing, doctor blade coating, roll coating, curtain coating, extrusion slot die coating, or dip coating.

[0104] According to the applicant's findings, a mesoporous layer having mesopores with an average diameter between 2 nm and 50 nm is obtained in a subsequent step of this method by aggregates or aggregates of nanoparticles with an average diameter between 80 nm and 300 nm (preferably between 100 nm and 200 nm).

[0105] In the present invention, the porous electrode layer can be deposited from a sufficiently concentrated suspension containing nanoparticle aggregates or aggregates of the active material P by an inkjet printing method, or by a coating method, particularly by a dip coating method, a roll coating method, a curtain coating method, a slot die coating method, or a doctor blade coating method.

[0106] Furthermore, while it is possible to deposit the porous electrode layer by electrophoresis, it is advantageous to use a less concentrated suspension containing nanoparticle aggregates of the active material P.

[0107] Methods for depositing aggregates or aggregates of nanoparticles by electrophoresis, dip coating, inkjet, roll coating, curtain coating, slot die coating, or doctor blade coating are simple, safe, easy to implement and industrialize, and ultimately yield a homogeneous porous layer. Electrophoretic deposition allows for high deposition rates and uniform layer deposition over a wide area. Coating techniques, particularly those mentioned above, allow for easier tank management compared to electrophoretic deposition because the suspension does not deplete particles during deposition. Inkjet printing deposition enables localized deposition.

[0108] A porous layer consisting of a thick layer can be fabricated in a single step by roll coating, curtain coating, slot die coating, or doctor blade coating (i.e., using a doctor blade).

[0109] It should be noted that colloidal suspensions in water and / or ethanol and / or IPA, and mixtures thereof, have greater fluidity than those obtained in NMP. Therefore, it is possible to increase the dry extract in the suspension of nanoparticle aggregates. These aggregates, even if they are two groups of different sizes, preferably have a size of 200 nm or less and have a polydisperse size.

[0110] Compared to prior art, the formulation of inks and pastes for electrode fabrication is simpler. Increasing the amount of dry extract does not increase the risk of carbon black aggregation in the suspension.

[0111] (3. Deposition and solidification of layers) Generally, layers of nanoparticle suspensions are deposited on a substrate by any suitable technique, particularly by a method selected from the group consisting of electrophoresis, printing (preferably inkjet printing or flexographic printing), coating (preferably doctor blade coating, roll coating, curtain coating, dip coating, or slot die coating). The aforementioned suspensions are typically in the form of ink, i.e., a sufficiently fluid liquid, but can also have a paste-like viscosity. The application of deposition techniques and deposition methods must be suitable for the viscosity of the suspension, and vice versa.

[0112] Subsequently, the deposited layer is dried. Then, the aforementioned layer is solidified to obtain the desired mesoporous ceramic structure. This solidification is described below. This can be done by heat treatment, by mechanical treatment followed by heat treatment, or optionally by thermomechanical treatment, typically by thermal compression. During this thermomechanical or heat treatment, the electrode layer becomes free of any organic components and organic residues (e.g., the liquid phase of the nanoparticle suspension and any surfactants), i.e., it becomes an inorganic layer (ceramic). The solidification of the plate is preferably carried out after separation from its intermediate substrate, because the latter is at risk of degradation during this process.

[0113] The deposition, drying, and solidification of layers can present several problems, which will be discussed here. These problems are partly related to the fact that shrinkage occurs during the solidification of layers, which creates internal stress.

[0114] (3.1. Circuit board capable of functioning as a current collector) In the first embodiment, each electrode layer is deposited on a substrate capable of functioning as an electrostatic current collector. Layers containing a suspension of nanoparticles or aggregates of nanoparticles can be deposited on one or both surfaces by the deposition technique described above. The substrate that functions as a current collector in a battery using the porous electrodes of the present invention can be a metal, for example, a metal strip (i.e., a laminated metal sheet). The above-mentioned substrate is preferably selected from strips of tungsten, molybdenum, chromium, titanium, tantalum, stainless steel, or an alloy of two or more of these materials. A less noble substrate, such as copper or nickel, can be coated with a conductive and oxidation-resistant coating.

[0115] The aforementioned metal sheet can be coated with a noble metal layer selected from gold, platinum, palladium, titanium, or an alloy mainly containing at least one of these metals, or with a layer of ITO-type conductive material (which has the advantage of functioning as a diffusion barrier).

[0116] Generally, this substrate, capable of functioning as an electrostatic current collector, must withstand the heat treatment conditions of the deposited layers and the operating conditions within the battery cell. Therefore, copper and nickel are suitable for contact with the cathode material and can oxidize the anode.

[0117] Regarding the deposition of layers, electrophoresis (particularly in water) can be used. In this particular case, the aforementioned substrate undergoes electrochemical polarization in a suspension of nanoparticles, resulting in either oxidation or dissolution. In this case, only substrates that do not exhibit anodic oxidation and / or corrosion phenomena can be used. This is especially true for stainless steel and precious metals.

[0118] When the deposition of nanoparticles and / or aggregates is carried out by one of the other techniques described below (e.g., coating, printing), the choice of substrate can be broadened. Furthermore, this choice may be made depending on the stability of the metal at the operating potential of the electrode that is in contact with the electrolyte. However, depending on the synthesis route used to prepare the nanoparticles, some degree of strong heat treatment is necessary for the solidification and anticipated recrystallization of the nanopowder. This aspect is further described in Section 5 below.

[0119] In all cases, a solidification heat treatment is required to obtain this mesoporous electrode. It is important that the substrate capable of functioning as an electrostatic current collector can withstand this heat treatment without oxidation. Several approaches can be used.

[0120] When nanopowder deposited on a substrate by ink technology is amorphous and / or has many point defects, in addition to solidification, a heat treatment is necessary to recrystallize the material into a suitable crystalline phase with appropriate stoichiometric properties. For this purpose, heat treatment at a temperature of 500°C to 700°C is generally required. Furthermore, the aforementioned substrate must withstand this type of heat treatment, and a material that can withstand this high-temperature treatment must be used. Strips of stainless steel, titanium, molybdenum, tungsten, tantalum, chromium, and their alloys can be used, for example.

[0121] When nanopowder and / or aggregates are crystallized by hydrothermal or solvent-thermal synthesis in a suitable phase and crystal structure, less noble substrates such as nickel, copper, and aluminum can be used. Furthermore, solidification heat treatment under a controlled atmosphere is possible. Since the primary particles obtained by hydrothermal synthesis are extremely small, the temperature and / or duration of the solidification heat treatment can be reduced to values ​​close to 350°C to 500°C, thereby broadening the range of substrate choices. However, these less noble substrates must withstand heat treatment that can remove organic additives, such as ligands, stabilizers, binders, or residual organic solvents (debinding), which may be present in the suspension of nanoparticles used. This heat treatment is preferably carried out under an oxidizing atmosphere.

[0122] It is also possible to obtain amorphous nanoparticles that require subsequent recrystallization through pseudo-hydrothermal synthesis.

[0123] This substrate, which can function as an electrostatic current collector, can optionally be covered with a thin film of conductive oxide. This oxide may have the same composition as the electrode. This thin film can be fabricated by sol-gel. This oxide boundary can suppress corrosion of the substrate and ensure a good mounting base for the electrode to the substrate.

[0124] Regarding the operating conditions within the battery cell, it is important to first note that in the battery using porous electrodes according to the present invention, the liquid electrolyte impregnated into the porous electrodes is in direct contact with a substrate capable of functioning as a current collector. However, when this electrolyte comes into contact with a substrate capable of functioning as a current collector, i.e., a metal substrate that is polarized at a potential that is extremely anode to the cathode and extremely cathode to the anode, this electrolyte can cause the current collector to dissolve. This parasitic reaction can degrade battery life and accelerate its natural discharge. To prevent this, a substrate capable of functioning as a current collector, such as an aluminum current collector, is used in the cathode of all lithium-ion batteries. Aluminum has the property of being anodized at this extremely anode, and the oxide layer thus formed on its surface protects it from dissolution. However, aluminum has a melting point of nearly 600°C, and if the solidification process of the electrode could melt the current collector, it cannot be used in the manufacture of the battery according to the present invention.

[0125] Therefore, to prevent parasitic reactions that can degrade battery life and accelerate its self-discharge, titanium strips are advantageously used as cathode current collectors. When the battery is operating, the titanium strips can be anodized, like aluminum, and their oxide layer can prevent any parasitic reactions such as the dissolution of titanium upon contact with the liquid electrolyte. Furthermore, since titanium has a much higher melting point than aluminum, the all-solid electrodes in this invention can be fabricated directly onto this type of strip.

[0126] Furthermore, the use of these heavy materials, particularly titanium, copper, or nickel strips, can protect the cut edges of the battery electrodes from corrosion.

[0127] Furthermore, stainless steel can be used as a current collector, especially when it contains titanium or aluminum as an alloying element, or when it has a thin layer of protective oxide.

[0128] Other substrates that function as current collectors can be used, such as strips of less noble metal covered with a protective coating, and the presence of an electrolyte can prevent the potential dissolution of these strips caused by their contact.

[0129] These less noble metal strips can be made of copper, nickel, or metal alloys such as stainless steel strips, Fe-Ni alloys, Be-Ni-Cr alloys, Ni-Cr alloys, or Ni-Ti alloy strips.

[0130] The coatings that can be used to protect a circuit board that functions as a current collector can have a variety of properties. • A thin layer obtained by the sol-gel method using the same material as the electrode; because this film is non-porous, contact between the electrolyte and the metal current collector can be prevented. • Thin layers obtained by vacuum deposition using the same material as the electrode, particularly by physical vapor deposition (PVD) or chemical vapor deposition (CVD), • Dense, defect-free thin layers of metal, such as gold, titanium, platinum, palladium, tungsten, or molybdenum, can be used to protect current collectors because they possess good conductivity and can withstand heat treatment during subsequent electrode manufacturing processes. These layers can be fabricated by electrochemical methods, PVD, CVD, vapor deposition, or ALD. • After heat treatment, a carbon-doped inorganic phase can be obtained to make it conductive, such as a thin layer of carbon such as diamond or graphite-carbon deposited by ALD, PVD, CVD, or sol-gel solution ink technology. • Because oxides decrease at low potentials, conductive or semiconductor oxide layers such as ITO (indium tin oxide) layers are deposited only on the cathode substrate. Since the nitride absorbs lithium at low potentials, it can be used to form a conductive nitride layer, such as a TiN layer, which is deposited only on the cathode substrate.

[0131] A coating that can be used to protect a substrate that functions as a current collector must be electrically conductive so as not to interfere with the operation of electrodes later deposited on the coating by making it too resistive.

[0132] Generally, to avoid significantly affecting the operation of the battery cell, the operating potential of the electrodes is measured on a substrate that can function as a current collector, in μA / cm². 2 The maximum dissolution current expressed as μAh / cm² is 2 The electrode surface capacitance must be 1000 times lower than that represented by [formula]. When attempting to increase the electrode thickness, it has been observed that shrinkage due to solidification can lead to either cracking of the layer or shear stress at the boundary between the substrate (which has predetermined dimensions) and the ceramic electrode. When this shear stress exceeds a threshold, the layer delaminates from its substrate.

[0133] To prevent this phenomenon, it is preferable to increase the electrode thickness by a continuous deposition-sintering process. This first modification in the first embodiment of layer deposition yields good results, but is not very productive. Alternatively, in the second modification, a thicker layer is deposited on both sides of a perforated substrate. This hole needs to be of sufficient diameter so that the two layers, front and back, are in contact at the hole. Therefore, during solidification, nanoparticles and / or aggregates of nanoparticles of the electrode material that come into contact through the hole in the substrate are brought together to form adhesion points (meeting points between the two deposits). This ensures that the adhesion of the layer to the substrate is not lost during the solidification step.

[0134] To prevent this phenomenon, that is, to increase the deposition thickness while suppressing or eliminating the occurrence of cracks, binders and dispersants can be added. These additives and organic solvents can be removed during the sintering process or during heat treatment performed before the sintering process, preferably by heat treatment in an oxidizing atmosphere, for example, by a de-bindering process.

[0135] (3.2. Intermediate board) In a second embodiment, the electrode layer is deposited on a temporary intermediate substrate rather than on a substrate capable of functioning as an electrostatic collector. In particular, a sufficiently thick layer (referred to as a "green sheet") can be deposited from a suspension of nanoparticles and / or aggregates of nanoparticles that is more concentrated (i.e., not very fluid, preferably paste-like). This thick layer is deposited, for example, by a coating method, preferably by a doctor blade coating method (a technique known in the term "tape casting") or a slot die coating method. The aforementioned intermediate substrate can be a polymer sheet, for example, poly(ethylene terephthalate) abbreviated as PET. During drying, in particular when drying after separating the layer obtained in step (b) from its intermediate substrate, the layer does not crack. Due to solidification by heat treatment (and preferably due to drying already performed beforehand), it can be peeled off its substrate. Thus, after cutting off the electrode, referred to as the "green" electrode, a plate can be obtained, and after calcination and partial sintering of this plate, a mesoporous, self-supporting ceramic plate can be obtained.

[0136] Subsequently, a stack of three layers is fabricated, namely plates of two electrodes of the same polarity separated by electrically conductive sheets capable of functioning as current collectors, such as metal sheets or graphite sheets. This stack is then assembled by thermomechanical processing, preferably including simultaneous pressurization and heat treatment. Alternatively, the boundaries may be coated with a layer that enables electronically conductive adhesion to facilitate bonding between the ceramic plate and the metal sheet. This layer may optionally be a sol-gel layer (preferably of a type that allows the chemical composition of the electrodes to be obtained after heat treatment) with added particles of an electronically conductive material capable of ceramic welding the mesoporous electrode and the metal sheet. This layer may also consist of a thin layer of non-sintered electrode nanoparticles, or a thin layer of conductive adhesive (e.g., with added graphite particles), or a metal layer of a metal having a low melting point.

[0137] The electrically conductive sheets described above, when made of metal, are preferably laminated sheets, i.e., obtained by lamination. After lamination, a final annealing process can optionally be performed, which can be (whole or partial) softening or recrystallization annealing, depending on the metallurgical terminology. Alternatively, electrochemically deposited sheets, such as electrodeposited copper sheets or electrodeposited nickel sheets, can also be used.

[0138] In any case, without an organic binder, ceramic electrodes are obtained that are mesoporous and function as electron current collectors, and are placed on both sides of a metal substrate.

[0139] (4. Deposition of the active material P layer) In general, as already described above, the electrodes in the present invention can be manufactured from a suspension of nanoparticles using known coating techniques. These techniques include tape casting and coating techniques, such as roll coating, doctor blade coating, slot die coating, and curtain coating. Dip coating techniques can also be used.

[0140] In all of these techniques, it is advantageous for the dried extract of the suspension to exceed 20%, preferably exceed 40%, as this reduces the risk of cracking during drying.

[0141] In addition, printing technologies such as flexographic technology and inkjet printing technology can also be used.

[0142] Electrophoresis can also be used.

[0143] In the first embodiment, the method of the present invention advantageously uses electrophoresis of a nanoparticle suspension as a technique for depositing a porous, preferably mesoporous, electrode layer. Methods for depositing electrode layers from a nanoparticle suspension are known in themselves (see, for example, European Patent No. 2774194). The substrate described above can be a metal, for example, a metal sheet. The substrate that functions as a current collector in a battery using the porous electrode of the present invention is preferably selected from titanium, copper, stainless steel, or molybdenum strips.

[0144] As a substrate, for example, a sheet of stainless steel with a thickness of 5 μm can be used. The aforementioned metal sheet can be coated with a layer of noble metal selected from gold, platinum, palladium, titanium, or an alloy mainly containing at least one of these metals, or with a layer of ITO-type conductive material (which has the advantage of also functioning as a diffusion barrier).

[0145] In certain embodiments, a layer, preferably a thin layer, of electrode material is deposited on a metal layer. This deposition needs to be extremely thin (typically tens of nanometers, more commonly between 10 nm and 100 nm). This can be done by a sol-gel method. For example, LiMn2O4 can be used as a porous LiMn2O4 cathode.

[0146] To perform electrophoresis, a counter electrode is placed in the suspension, and a voltage is applied between the conductive substrate and the aforementioned counter electrode.

[0147] In an advantageous embodiment, the deposition of aggregates or aggregates of nanoparticles by electrophoresis is performed by pulsed-mode constant-current electrodeposition. That is, a high-frequency current pulse is applied to prevent the formation of bubbles on the electrode surface and fluctuations in the electric field in the suspension during deposition. Therefore, the thickness of the electrode layer thus deposited by electrophoresis, preferably by pulsed-mode constant-current electrodeposition, is advantageously less than 10 μm, preferably less than 8 μm, and more preferably between 1 μm and 6 μm.

[0148] To deposit a very thick layer by electrophoresis, carbon black nanoparticles can be added to the suspension so as to increase the electron conductivity of the deposit before solidification. These carbon black nanoparticles can be removed by oxidation during the heat treatment for solidification.

[0149] In other embodiments, aggregates or agglomerates of nanoparticles can be deposited by dip coating, regardless of the chemical properties of the nanoparticles used. This deposition method is preferred when the nanoparticles used have little or no charge. To obtain a layer of desired thickness, the steps of depositing aggregates or agglomerates of nanoparticles by dip coating and then drying the resulting layer are repeated as necessary. To increase the thickness of the crack-free layer, it is advantageous to use at least one organic additive, such as a ligand, stabilizer, thickener, binder, or residual organic solvent, in the colloidal suspension or paste to be deposited. This continuous dip coating / drying step is time-consuming, but the dip coating deposition method is a simple, safe, easy-to-implement and industrialize method that can obtain a homogeneous and dense final layer.

[0150] (5. Solidification treatment of the deposited layer) The deposited layer needs to be dried. Drying must not cause crack formation. For this reason, this can be done under controlled humidity and temperature conditions, or, to produce a porous layer, in addition to aggregates or agglomerates of monodisperse primary nanoparticles, at least one electrode active material P in the present invention, an organic additive such as a ligand, stabilizer, thickener, binder, or a colloidal suspension and / or paste containing a residual organic solvent is preferably used.

[0151] The dried layer can be solidified by pressurization and / or heating (heat treatment). In a highly advantageous embodiment of the present invention, this process causes primary nanoparticles to partially coalesce within aggregates or assemblies and between adjacent aggregates or assemblies. This phenomenon is called "necking" or "neck formation." It is characterized by the partial coalescence of two contacting particles that are separated but connected by a (constricted) neck. This is schematically shown in Figures 3 and 4. Lithium ions and electrons can move within these necks and diffuse from particle to particle without encountering grain boundaries. The nanoparticles (Figure 3) associate together to ensure the conduction of electrons from one particle to the other (Figure 4). Thus, a continuous mesoporous film is formed from the primary nanoparticles, forming a three-dimensional network with high ion mobility and electron conductivity. This network includes interconnected pores, preferably mesopores.

[0152] The temperature required to obtain "necking" is determined by the material. Considering the diffusion properties of this phenomenon that causes necking, the duration of the process is determined by the temperature. This method can be called sintering. Depending on the duration and temperature, more or less obvious bonding (necking) is obtained, affecting the porosity. Therefore, it is possible to reduce the porosity to 30% (or even 25%) while maintaining a sufficiently homogeneous channel size.

[0153] Furthermore, heat treatment can be used to remove organic additives, such as ligands, stabilizers, binders, or residual organic solvents, which may be present in the suspension of nanoparticles used. In other modifications, further heat treatment in an oxidizing atmosphere may be performed to remove these organic additives, which may be present in the suspension of nanoparticles used. This further heat treatment can be advantageously performed on a porous layer separated from an intermediate substrate when an intermediate substrate is used. This further heat treatment can be advantageously performed before the solidification treatment of step (c) which yields a porous layer, preferably a mesoporous layer.

[0154] (6. Deposition of coatings made of electronically conductive materials) An important feature of the present invention is that the coating of the electronically conductive material is deposited in and within the pores of the porous layer described above.

[0155] In fact, as described above, the method of the present invention, which inevitably involves the step of depositing aggregated nanoparticles of electrode material (active material), causes the nanoparticles to spontaneously "associate" with each other, and after solidification such as annealing, it creates a porous and rigid three-dimensional structure without an organic binder. This porous layer, preferably a mesoporous layer, is well-suited to the application of surface treatment with gas or liquid that penetrates deep into the open porous structure of the layer.

[0156] A significant advantage is that this deposition is carried out by a technique (also called "conformal deposition") that enables sealing coating, where the deposition faithfully reproduces the atomic topography of the substrate to which it is applied and penetrates deep into the open porous network of the layer. The aforementioned electronically conductive material can be carbon.

[0157] ALD (atomic layer deposition) or CSD (chemical solution deposition) techniques are known and may be appropriate. These can be applied to the porous layer after manufacturing, before the deposition of separator particles, and before cell assembly. ALD deposition is performed layer by layer in a periodic manner, and can produce a sealing coating that faithfully reproduces the topography of the substrate. The coating extends along the entire surface of the electrode. This sealing coating typically has a thickness ranging from 1 nm to 5 nm.

[0158] ALD deposition is typically carried out at temperatures between 100°C and 300°C. It is important that the layer is free of organic matter. This means that it must not contain any organic binders, and any residue of stabilizing ligands used to stabilize the suspension must be removed by purification of the suspension and / or during heat treatment of the layer after drying. In fact, at the temperatures of ALD deposition, there is a risk that organic materials that form organic binders (e.g., polymers contained in electrodes made by tape casting of ink) will decompose and contaminate the ALD reactor. Furthermore, the presence of residual polymers in contact with the active material particles of the electrodes may prevent the ALD coating from sealing all particle surfaces, which impairs its effectiveness.

[0159] Furthermore, CSD deposition technology allows for the fabrication of a encapsulation coating of an electronically conductive material precursor that faithfully reproduces the substrate topography. This coating extends along the entire surface of the electrode. This encapsulation coating typically has a thickness of less than 5 nm, preferably between 1 nm and 5 nm. This then needs to be converted into an electronically conductive material. In the case of a carbon precursor, this can preferably be done by thermal decomposition in an inert gas (such as nitrogen).

[0160] In this modification, which involves depositing nanolayers of electronically conductive material, the diameter D of the primary particles of the electrode material is such that the conductive layer does not block the open pores of the electrode layer. 50 Preferably, the wavelength is at least 10 nm.

[0161] (7. Electrolytes) Although the electrolyte is not part of the present invention, it is necessary for the formation of the battery cell, and therefore it is useful to describe it herein. The electrode in the present invention does not contain organic compounds. The absence of these organic compounds, in conjunction with the mesoporous structure, promotes wetting by the lithium ion-conducting electrolyte. Furthermore, this electrolyte can be selected without distinction from the group consisting of an electrolyte composed of an aprotic solvent and a lithium salt, an electrolyte composed of an ionic liquid or poly(ionic liquid) and a lithium salt, a mixture of an aprotic solvent and an ionic liquid or poly(ionic liquid) and a lithium salt, an ion-conducting polymer containing a lithium salt, and an ion-conducting polymer.

[0162] The ionic liquid described above can be a salt that melts at room temperature (this product is known as RTIL, or room-temperature ionic liquid), or an ionic liquid that is solid at room temperature. This room-temperature solid ionic liquid needs to be heated to liquefy in order to impregnate the electrode. It then solidifies at the electrode. The ion-conducting polymer described above can be melted for mixing with the lithium salt, and this molten phase can then be impregnated into the mesopores of the electrode.

[0163] Similarly, the polymer described above can be a liquid at room temperature, or a solid that is heated to become liquid for impregnation into a mesoporous electrode. [Examples]

[0164] (8. Examples of advantageous embodiments) Generally, when lithium-ion batteries need to operate at high temperatures, it is advantageous to use one of the materials listed above as the cathode material P, which does not contain manganese, such as LiFePO4 or LiCoPO4. In this case, the anode is advantageously a titanate, a mixed oxide of titanium and niobium, or a derivative of a mixed oxide of titanium and niobium, and the cell is impregnated with an ionic liquid containing a lithium salt. If the ionic liquid contains sulfur atoms, it is preferable that the substrate be a noble metal.

[0165] Some embodiments and examples of the electrodes in the present invention are described herein so that those skilled in the art can perform the method of the present invention.

[0166] In the first advantageous embodiment, the mesoporous anode is made of Li4Ti5O 12 or Li4Ti 5-x M x O 12 A suspension of substance P (wherein M = V, Zr, Hf, Nb, Ta) is prepared according to the present invention for lithium-ion batteries. Figure 1 shows the Li4Ti5O used in the suspension. 12 Figure 2 shows a typical X-ray diffractogram of the nanopowder, and Figure 3 shows a photograph obtained by transmission electron microscopy of this primary nanoparticle.

[0167] This material is deposited on a metal substrate, which is then heat-treated (sintered) to cover it with a layer of electronically conductive material several nanometers thick. This layer is referred to herein as the "nanocoating." The nanocoating is preferably carbon. This carbon nanocoating can be fabricated by impregnating it in a carbon-rich liquid phase and then thermally decomposing it in nitrogen, or by ALD deposition. This anode absorbs lithium at a potential of 1.55V, resulting in extremely high output and enabling ultrafast charging.

[0168] In a second advantageous embodiment, the mesoporous anode in the present invention is TiNb2O7, or Li w Ti 1-x M 1 x Nb 2-y M 2 y O7 (in the formula, M 1 and M 2 The material P is manufactured for lithium-ion batteries, where each element is at least one element selected from the group consisting of Nb, V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs, and Sn. 1 and M 2They can be the same or different from each other, where 0 ≤ w ≤ 5, 0 ≤ x ≤ 1, and 0 ≤ y ≤ 2. This layer is deposited on a metal substrate, sintered, and covered with an electronically conductive nanocoating, preferably carbon, deposited as described for the previous embodiments. This anode has extremely high output and enables rapid charging.

[0169] In a third advantageous embodiment, the mesoporous anode is made of Nb2O 5±δ or Nb 18 W 16 O 93±δ or Nb 16 W5O 55±δ (where 0 ≤ x < 1, 0 ≤ δ ≤ 2), or La x Ti 1-2x Nb 2+x O7 (where 0 < x < 0.5), or Ti 1-x Ge x Nb 2-y M 1 y O 7±z or Li w Ti 1-x Ge x Nb 2-y [[ID=4)]M 1 y O 7±z or Ti 1-x Ce x Nb 2-y M 1 y O 7±z or Li w Ti 1-x Ce x Nb 2-y M 1 y O 7±z (where M 1 is at least one element selected from the group consisting of Nb, V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs, and Sn, where 0 ≤ w ≤ 5, 0 ≤ x ≤ 1, 0 ≤ y ≤ 2, z ≤ 0.3), or Ti 1-x Ge x Nb 2-y M 1 y O 7-z M2 z Or Li w Ti 1-x Ge x Nb 2-y M 1 y O 7-z M 2 z or 1-x Ce x Nb 2-y M 1 y O 7-z M 2 z Or Li w Ti 1-x Ce x Nb 2-y M 1 y O 7-z M 2 z (In the formula, M 1 and M 2 Each of these is at least one element selected from the group consisting of Nb, V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs, Ce, and Sn, and M 1 and M 2 The material P is such that it may be the same as or different from each other, where 0 ≤ w ≤ 5, 0 ≤ x ≤ 1, 0 ≤ y ≤ 2, z ≤ 0.3, and is manufactured according to the present invention for lithium-ion batteries. This layer is deposited on a metal substrate, sintered, and covered with an electronically conductive nanocoating, preferably carbon, which is deposited as described in relation to the earlier embodiments. This anode has extremely high power output and enables rapid charging.

[0170] In the fourth embodiment, the mesoporous anode is made of TiNb2O 7-z M 3 z , or Li w Ti 1-x M 1 x Nb 2-y M 2 y O 7-z M 3 z (In the formula, M1 and M 2 The material P is a substance that is produced according to the present invention for lithium-ion batteries, where each element is at least one element selected from the group consisting of Nb, V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs, and Sn. 1 and M 2 They may be the same or they may be different from each other. The relationships 0≦w≦5, 0≦x≦1, and 0≦y≦2 are applied. 3 This is at least one halogen, and z ≤ 0.3. As described in relation to the second embodiment, this layer is deposited on a metal substrate, sintered, and covered with a nanocoating that may be carbon, deposited as described above. This anode is extremely high power and can be rapidly charged.

[0171] In a fifth embodiment, a mesoporous anode is manufactured according to the present invention for a lithium-ion battery using material P, which is TiO2 or LiSiTON. The manufacturing is carried out as described with respect to the other embodiments. This electrode is extremely high-power and can be rapidly charged.

[0172] In a sixth exemplary embodiment, a mesoporous cathode is prepared according to the present invention for a lithium-ion battery using material P, which is LiMn2O4. These nanoparticles are used in "One pot hydrothermal synthesis and electrochemical characterization of Li 1+x Mn 2-yThese compounds can be obtained by hydrothermal synthesis using the method described in the article "O4spinel structured compounds," Energy Environ. Sci., 3, pp. 1339-1346. In this synthesis, a small amount of PVP was added to prepare the size and shape of the resulting aggregates. The latter consists of primary particles that are spherical in shape, have a diameter of approximately 150 nm, and are between 10 nm and 20 nm in size. After centrifugation and washing, approximately 10% to 15% by mass of PVP 360k was added to an aqueous suspension, and the water was evaporated to obtain a 10% dry extract. The resulting ink was applied to a stainless steel sheet and dried to obtain a layer of approximately 10 microns. This sequence can be repeated several times to increase the thickness of the deposit. The resulting deposit was annealed in air at 600°C for 1 hour to solidify the nanoparticle aggregates relative to each other.

[0173] Subsequently, the mesoporous layer was impregnated with a sucrose solution and then annealed at 400°C in nitrogen to obtain an electronically conductive carbon layer on the entire mesoporous surface of the electrode. The thickness of this carbon layer was several nanometers. The electrolyte layer to be impregnated thereafter, in this case Li3PO4, was deposited on this mesoporous cathode. In the sixth exemplary embodiment, a battery was manufactured according to the present invention, and the battery was, -Li4Ti5O 12 and / or a mesoporous anode containing TiO2 (50% porosity), -Mesoporous cathode containing LiMn2O4 (50% porosity), -Formed from a mesoporous electrolyte separator (50% porosity) containing Li3PO4.

[0174] The electrode substrate was made from 316L stainless steel. The ionic impregnation liquid was a mixture of 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (abbreviated as Pyr14TFSI) and lithium bis(fluorosulfonyl)imide (abbreviated as LiTFSI) at 0.7 M.

[0175] Figure 5 shows the change in the relative capacity of the battery according to the present invention, depending on the number of charge and discharge cycles. Each discharge was performed to a depth of 100% of the battery capacity. No loss of relative capacity of the battery was observed. The battery according to the present invention has excellent durability in charge-discharge cycles.

[0176] Figure 6 shows the charging curve of this battery. It can be seen that 80% of the battery capacity can be charged in less than 5 minutes. This rapid charging performance provides significant advantages in use.

Claims

1. A method for manufacturing a porous electrode for an electrochemical device, wherein the porous electrode comprises a porous layer deposited on a substrate, the substrate being an electrostatic current collector or an intermediate substrate adapted to temporarily support the porous layer, the porous layer being binder-free, having a porosity between 20% and 60% by volume, and pores having an average diameter of less than 50 nm, and the manufacturing method is: (a) A colloidal suspension or paste comprising a substrate and an aggregate or aggregate of monodisperse primary nanoparticles of at least one electrode active material P, wherein the monodisperse primary nanoparticles have a primary mean diameter D between 2 nm and 150 nm. ５０ The aggregate or aggregate has an average diameter D between 50 nm and 300 nm. ５０ The steps include preparing a colloidal suspension or paste having, (b) A step of depositing a layer from the colloidal suspension or paste prepared in step (a) onto at least one surface of the substrate by a method selected from the group consisting of electrophoresis, printing, and coating, (c) A step of drying the layer obtained in step (b), and then solidifying the dried layer by pressurization and / or heating to obtain the porous layer, (d) A method characterized by the step of depositing a coating of an electronically conductive material in and within the pores of the porous layer.

2. The method according to claim 1, wherein the substrate is an intermediate substrate adapted to temporarily support the porous layer, and the layer obtained in step (b) is dried in step (c) before or after separating the layer from the substrate.

3. The method according to claim 1, wherein the dried layer in step (c) is heat-treated before it solidifies.

4. The porous layer obtained from step (c) is 10 m ２ / g to 500m ２ The method according to claim 1, wherein the specific surface area is contained within the range of / g.

5. The method according to any one of claims 1 to 4, wherein the porous layer obtained in step (c) has a thickness between 4 μm and 400 μm.

6. The method according to any one of claims 1 to 4, wherein the substrate is the intermediate substrate, and the layer is separated from the intermediate substrate before or after drying in step (c) to form a porous plate.

7. A method for heat-treating the layer dried in step (c) according to any one of claims 1 to 5, or the porous plate formed in step (c) according to claim 6, wherein the colloidal suspension or paste prepared in step (a) contains an organic additive or a residual organic solvent.

8. The method according to any one of claims 1 to 4, wherein the porous layer has a porosity between 25% by volume and 50% by volume.

9. The primary average diameter D of the colloidal suspension or paste comprising an aggregate or aggregate of monodisperse primary nanoparticles of at least one electrode active material P. ５０ The method according to any one of claims 1 to 4, wherein the wavelength is between 2 nm and 100 nm.

10. The aggregates or aggregates of monodisperse primary nanoparticles in the colloidal suspension or paste have an average diameter D between 100 nm and 200 nm. ５０ The method according to any one of claims 1 to 4, having the following characteristics.

11. The method according to any one of claims 1 to 4, wherein the electronically conductive material is carbon.

12. The method according to any one of claims 1 to 4, wherein the deposition of the coating of the electronically conductive material is carried out by atomic layer deposition (ALD) technology, or by immersing the porous layer in a liquid phase containing a precursor of the electronically conductive material, and then converting the precursor into the electronically conductive material.

13. The method according to claim 12, wherein the deposition of the coating of the electronically conductive material is carried out by immersing the porous layer in a liquid phase containing a precursor of the electronically conductive material, and then converting the precursor into the electronically conductive material, wherein the precursor is a carbon precursor, and the conversion to the electronically conductive material is carried out by thermal decomposition.

14. The electrode active material P is LiMn of o-oxide ２ O ４ 、Li １＋ｘ Mn ２－ｘ O ４ (where 0 < x < 0.15), LiCoO ２ 、LiNiO ２ 、LiMn １．５ Ni ０．５ O ４ 、LiMn １．５ Ni ０．５－ｘ X ｘ O ４ (where X is selected from Al, Fe, Cr, Co, Rh, Nd, other rare earths (including Sc, Y, Lu, La, Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb), 0 < x < 0.1), LiMn ２－ｘ M ｘ O ４ (where M = Er, Dy, Gd, Tb, Yb, Al, Y, Ni, Co, Ti, Sn, As, Mg, or a mixture of these compounds, 0 < x < 0.4), LiFeO ２ 、LiMn １／３ Ni １／３ Co １／３ O ２ 、LiNi ０．８ Co ０．１５ Al ０．０５ O ２ 、LiAl ｘ Mn ２－ｘ O ４ (where 0 ≤ x < 0.15), LiNi １／ｘ Co １／ｙ Mn １／ｚ O ２ (where x + y + z = 10), oLi ｘ M ｙ O ２ (wherein 0.6 ≤ y ≤ 0.85 and 0 ≤ x + y ≤ 2, and M is selected from Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Sn, and Sb, or mixtures thereof), Li １．２０ Nb ０．２０ Mn ０．６０ O ２ , oLi １＋ｘ Nb ｙ Me ｚ A ｐ O ２ (wherein Me is at least one transition metal selected from Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Rf, Db, Sg, Bh, Hs, and Mt, and 0.6 < x < 1, 0 < y < 0.5, 0.25 ≤ z < 1, where A ≠ Me, A ≠ Nb, and 0 ≤ p ≤ 0.2) oLi ｘ Nb ｙ－ａ N ａ M ｚ－ｂ P ｂ O ２－ｃ F ｃ (wherein 1.2 < x ≤ 1.75, 0 ≤ y < 0.55, 0.1 < z < 1, 0 ≤ a < 0.5, 0 ≤ b < 1, 0 ≤ c < 0.8, and M, N, and P are each at least one element selected from the group consisting of Ti, Ta, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh, and Sb.) oLi １．２５ Nb ０．２５ Mn ０．５０ O ２ 、 １．３ Nb ０．３ Mn ０．４０ O ２ 、 １．３ Nb ０．３ Fe ０．４０ O ２ 、 １．３ Nb ０．４３ Ni ０．２７ O ２ 、 １．３ Nb ０．４３ Co ０．２７ O ２ 、 １．４ Nb ０．２ Mn ０．５３ O ２ 、 oLi ｘ Ni ０．２ Mn ０．６ O ｙ (where 0.00 ≦ x ≦ 1.52, 1.07 ≦ y < 2.4), Li １．２ Ni ０．２ Mn ０．６ O ２ , oLiNi ｘ Co ｙ Mn １-ｘ-ｙ O ２ (where 0 ≤ x, y ≤ 0.5), LiNi ｘ Ce ｚ Co ｙ Mn １-ｘ-ｙ O ２ (where 0 ≤ x, y ≤ 0.5 and 0 ≤ z), oLiFePO4 phosphate ４ LiMnPO ４ LiCoPO ４ LiNiPO ４ Li ３ V ２ (PO ４ ) ３ Li ２ MPO ４ F (wherein M = Fe, Co, Ni, or a mixture of these elements), LiMPO ４ F (wherein M = V, Fe, T, or a mixture of these elements), formula LiMM'PO ４ Phosphates of (wherein M and M' (M≠M') are selected from Fe, Mn, Ni, Co, V, or LiFe) ｘ Co １－ｘ PO ４ (and such that 0 < x < 1) oFe ０．９ Co ０．１ OF, LiMSO ４ F (where M = Fe, Co, Ni, Mn, Zn, Mg), o Chalcogenides below, V ２ O ５ , V ３ O ８ TiS ２ Titanium oxysulfide (TiO ｙ S ｚ In the formula, z = 2 - y and 0.3 ≤ y ≤ 1), tungsten oxysulfide (WO ｙ S ｚ In the formula, 0.6 < y < 3 and 0.1 < z < 2), CuS, CuS ２ All forms of lithiation, oLi ｘ V ２ O ５ (in the formula, 0<x≦2), Li ｘ V ３ O ８ (in the formula, 0<x≦1.7), Li ｘ TiS ２ (wherein the formula, 0 < x ≤ 1), titanium and lithium oxysulfide Li ｘ TiO ｙ S ｚ (In the equation, z = 2 - y and 0.3 ≤ y ≤ 1 and 0 < x ≤ 1), Li ｘ WO ｙ S ｚ (In the equation, z = 2 - y and 0.3 ≤ y ≤ 1 and 0 < x ≤ 1), Li ｘ CuS (in the formula, 0<x≦1), Li ｘ CuS ２ The method according to any one of claims 1 to 4, wherein the formula is selected from the group consisting of (wherein 0 < x ≤ 1).

15. The electrode active material P is oLi ４ Ti ５ O １２ Li ４ Ti ５－ｘ M ｘ O １２ (In the formula, M = V, Zr, Hf, Nb, Ta, and 0 ≤ x ≤ 0.25) o Niobium oxide, and mixed niobium oxide with titanium, germanium, cerium, or tungsten. oNb ２ O ５±δ , Nb １８ W １６ O ９３±δ , Nb １６ W ５ O ５５±δ (In the formula, 0 ≤ x < 1 and 0 ≤ δ ≤ 2), LiNbO ３ , oTiNb ２ O ７±δ Li ｗ TiNb ２ O ７ (in the formula, w≧0), Ti １－ｘ M １ ｘ Nb ２－ｙ M ２ ｙ O ７±δ or Li ｗ Ti １－ｘ M １ ｘ Nb ２－ｙ M ２ ｙ O ７±δ (In the formula, M １ and M ２ Each of these is at least one element selected from the group consisting of Nb, V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs, and Sn, M １ and M ２ They are either identical or different from each other, and 0 ≤ w ≤ 5 and 0 ≤ x ≤ 1 and 0 ≤ y ≤ 2 and 0 ≤ δ ≤ 0.3). oLa ｘ Ti １－２ｘ Nb ２＋ｘ O ７ (In the formula, 0 < x < 0.5) oM ｘ Till １－２ｘ N﹂ ２＋ｘ Oh ７±δ 、 In formula o, M is an element with an oxidation state of +III, where 0 < x ≤ 0.20 and -0.3 ≤ δ ≤ 0.3, Ga ０．１０ Ti ０．８０ Nb ２．１０ O ７ Fe ０．１０ Ti ０．８０ Nb ２．１０ O ７ , oM ｘ Till ２－２ｘ N﹂ １０＋ｘ Oh ２９±δ 、 In formula o, M is an element with an oxidation state of +III, where 0 < x ≤ 0.40 and -0.3 ≤ δ ≤ 0.

3. Oh, yes. １－ｘ M １ ｘ N﹂ ２－ｙ M ２ ｙ Oh ７－ｚ M ３ ｚ or ｗ Till １－ｘ M １ ｘ N﹂ ２－ｙ M ２ ｙ Oh ７－ｚ M ３ ｚ 、 oIn the formula, M １ and M ２ Each of these is at least one element selected from the group consisting of Nb, V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs, and Sn. oM １ and M ２ They are either identical or different from each other. oM ３ is at least one halogen, For o0≦w≦5 and 0≦x≦1 and 0≦y≦2 and z≦0.3, oTiNb ２ O ７－ｚ M ３ ｚ or Li ｗ TiNb ２ O ７－ｚ M ３ ｚ However, M ３ is at least one halogen selected from F, Cl, Br, I, or a mixture thereof, and 0 < z ≤ 0.3, Oh, yes. １－ｘ Yes ｘ N﹂ ２－ｙ M １ ｙ Oh ７±ｚ 、Li ｗ Till １－ｘ Yes ｘ N﹂ ２－ｙ M １ ｙ Oh ７±ｚ 、T １－ｘ Yes ｘ N﹂ ２－ｙ M １ ｙ Oh ７±ｚ 、Li ｗ Till １－ｘ Yes ｘ N﹂ ２－ｙ M １ ｙ Oh ７±ｚ 、 oIn the formula, M １ is at least one element selected from the group consisting of Nb, V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs, and Sn. For o0≦w≦5 and 0≦x≦1 and 0≦y≦2 and z≦0.3, oTi １－ｘ Ge ｘ Nb ２－ｙ M １ ｙ O ７－ｚ M ２ ｚ 、 ｗ Ti １－ｘ Ge ｘ Nb ２－ｙ M １ ｙ O ７－ｚ M ２ ｚ 、 １－ｘ Ce ｘ Nb ２－ｙ M １ ｙ O ７－ｚ M ２ ｚ 、 ｗ Ti １－ｘ Ce ｘ Nb ２－ｙ M １ ｙ O ７－ｚ M ２ ｚ 、 oIn the formula, M １ and M ２ Each of these is at least one element selected from the group consisting of Nb, V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs, Ce, and Sn. oM １ and M ２ They are either identical or different from each other. For o0≦w≦5 and 0≦x≦1 and 0≦y≦2 and z≦0.3, oTiO ２ 、 The method according to any one of claims 1 to 4, wherein the selection is made from the group consisting of oLiSiTON.

16. A method for manufacturing a porous electrode for a lithium-ion battery, using the method according to any one of claims 1 to 15.

17. A method for manufacturing a battery, comprising a method for manufacturing a porous electrode according to any one of claims 1 to 15.

18. The method according to claim 17, wherein the battery is a lithium-ion battery.

19. The method according to claim 16, wherein the method for manufacturing a porous electrode according to any one of claims 1 to 15 is applied to the manufacture of a cathode or an anode.

20. The method according to claim 16 or 17, wherein the porous electrode is impregnated with an electrolyte.

21. The aforementioned electrolyte is an electrolyte comprising at least one aprotic solvent and at least one lithium salt, an electrolyte comprising at least one ionic liquid and at least one lithium salt, A mixture of at least one aprotic solvent, at least one ionic liquid, and at least one lithium salt. o A polymer made ion-conductive by adding at least one lithium salt, and The method according to claim 20, wherein the lithium ion-supported phase is selected from the group consisting of a polymer phase or a polymer with a mesoporous structure to which a liquid electrolyte has been added to make it ion-conductive.

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