WO2019058080A1

WO2019058080A1 - Method for depositing an electrolytic material in the form of a layer on the surface of a substrate having pores and/or protrusions

Info

Publication number: WO2019058080A1
Application number: PCT/FR2018/052331
Authority: WO
Inventors: Hélène PORTHAULT; Marie-Josephe ARMEL
Original assignee: Commissariat A L'energie Atomique Et Aux Energies Alternatives
Priority date: 2017-09-25
Filing date: 2018-09-24
Publication date: 2019-03-28
Also published as: FR3071419A1

Abstract

The invention relates to a method for depositing a material in the form of a layer on the surface of a substrate (17) having, on the surface thereof, pores and/or protrusions, said material being an electrolytic material comprising an organic or inorganic matrix comprising therein at least one ion-conducting additive selected from ion-conducting salts, ionic liquids or mixtures thereof, and optionally at least one organic solvent and optionally at least one inorganic additive of the oxide type, said method comprising the following successive steps: - at least a first step of wet-depositing, on the surface of the substrate, a first solution (19) comprising the ingredients of the material and/or precursors of all or part of the ingredients, said first solution having a predetermined viscosity; - at least a second step of wet-depositing, on the surface of the substrate, a second solution (23) comprising the ingredients of the material and/or precursors of all or part of the ingredients, said second solution having a higher viscosity than the viscosity of the first solution.

Description

METHOD FOR DEPOSITING AN ELECTROLYTIC MATERIAL IN THE FORM OF A

LAYER ON THE SURFACE OF A SUBSTRATE HAVING PORES AND / OR

LANDFORMS

DESCRIPTION

TECHNICAL AREA

The present invention relates to a method of manufacturing a wet electrolytic material in the form of a layer on the surface of a substrate having, on its surface, pores and / or reliefs.

This invention may find particular application in the field of energy storage devices, such as lithium accumulators, capacitors, where the method can be implemented for producing an electrolyte necessary for the operation of these devices. STATE OF THE ART

Deposition of materials on a substrate, for example in the form of thin layer (s), has long been the subject of much research, in particular to give the substrate specific properties sought, such as optical properties, electronic properties, which can not be otherwise met by the underlying substrate.

Among the techniques implemented, it can be mentioned:

- vapor phase deposition techniques, such as chemical vapor deposition (also known as CVD technique for "Chemical Vapor Deposition");

- wet deposition techniques.

More specifically, the vapor deposition technique, such as the CVD technique, generally requires working at low pressure and at high relative temperatures to generate vaporization. precursors of the material to be deposited, which, on the one hand, can generate toxic vapors and, on the other hand, also requires a significant thermal budget in terms of application temperatures and the energy required to put into operation pressure.

As for the wet deposition techniques, they cover multiple variants all having as a common denominator the use of a liquid solution comprising the constituent ingredients of the material or precursors thereof. Among these techniques, the technique of soaking-shrinkage (corresponding to the English terminology "dip-coating") is particularly widespread for the production of thin films on a substrate, generally plane, the thin films imparting the desired properties to the substrate and generally having a thickness of less than 200 nm.

Figure 1, attached, illustrates the different steps implemented for this technique with:

- For part a), a soaking operation of introducing the substrate to be coated 1 in a coating solution 3 contained in a tank 5, the substrate being introduced into the solution at a predetermined soaking rate;

- for part b), an immersion operation of leaving the substrate immersed in the solution (without applying motion to the substrate) for a given duration;

for part c), a removal operation consisting, as its name indicates, in removing the substrate from the coating solution, this removal being carried out at a predetermined withdrawal speed.

Once in the open, the substrate thus coated can be subjected to an evaporation step so as to remove all or part of the solvent contained in the coating solution and can also be subjected to different processing steps in order to to obtain the desired final material, which is the case when the coating solution comprises precursors of said material. The main parameters influencing the nature of the deposited layer are, on the one hand, the deposition conditions (for example, the soaking rate, the withdrawal speed, the immersion time, the reservoir geometry, the temperature) and the properties of the coating solution (for example, the viscosity, the evaporation rate of the solvent used, if any, the affinity between the coating solution and the substrate). Specific studies have been conducted by Chen et al. (Organic Electronics, 37 (2016), 458-464) and have been able to demonstrate a dependency between the thickness of the deposited film and the rate of shrinkage and, also, the viscosity of the coating solution, the resulting conclusion being that the combination of a high shrinkage rate and a coating solution having a high viscosity leads to films of non-uniform thickness.

Moreover, this deposition technique may show certain limits since the support intended to be coated is not a plane support and has a complex geometry, as it may be the case of a mechanical part such as a bolt or a nut. To cope with these difficulties, some authors as in JP 2012016640 have had the idea of associating with the technique of soaking-withdrawal a rotation system to ensure the recovery of the entire surface of the piece by the solution of coating. However, this type of system does not effectively cover a support having, for example, a porosity on its surface. In this case, especially when the viscosity of the coating solution is important, a layer is formed mainly on the surface but without penetrating into the pores thereby making a portion of the surface of the support inaccessible, as shown schematically. , in Figure 2, which illustrates a sectional view of a substrate having on its surface an open porosity 9 and a layer of material 11 deposited solely on the surface without reaching the inner surface of the pores. In view of what exists and the drawbacks inherent in the embodiments of the prior art, the inventors have set themselves the objective of proposing a method of manufacturing a deposited electrolytic material, wet, in the form of a layer on the surface of a substrate having, on its surface, pores and / or reliefs and which makes it possible to access a filling of the substrate porosity or of the reliefs present on the surface of the substrate and to obtain in the end a layer of homogeneous thickness on this substrate.

STATEMENT OF THE INVENTION

To do this, the inventors have developed a method of depositing a material in the form of a layer on the surface of a substrate having, on its surface, pores and / or reliefs, said material being a material electrolytic composition comprising an organic or inorganic matrix comprising, within it, at least one ion-conducting additive selected from ion-conducting salts, ionic liquids or mixtures thereof, and optionally at least one organic solvent and optionally at least one inorganic additive of the oxide type, said process comprising successively the following steps:

- At least a first step of depositing, wet, on the surface of the substrate, a first solution comprising the ingredients of the material and / or precursors of all or part of said ingredients, said first solution having a predetermined viscosity;

at least a second wet deposition step on the surface of the substrate of a second solution comprising the ingredients of the material and / or precursors of all or part of said ingredients, said second solution having a viscosity greater than the viscosity of the first solution.

Thus, by playing on the use of two solutions with different viscosities and more specifically, by playing on the use of a first solution having a given viscosity less than that of the second solution, it is possible to access, in a first step, a deposit with the ingredients of the first solution which will penetrate to the heart of the substrate and be deposited in all the tortuosities of the latter then, in a second step, to a thicker deposit which will, if necessary, complete the filling of the tortuosities of the substrate and result in a layer of material of uniform thickness smoothing the surface of the substrate. In addition, since the first solution and the second solution both contain the ingredients of the electrolytic material or precursors thereof, it is also possible to control the content of these ingredients in the final material (especially that of the ion-conducting additive), controlling the content thereof in both the first solution and the second solution. The deposition of the first solution can not therefore cause a dilution effect of the ingredients of the second solution, because each of these layers comprises these ingredients.

In what precedes and what follows, it is pointed out that viscosity generally means dynamic viscosity (conventionally expressed in Pa.s), which can be determined by shear rheology measurements. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 illustrates the different conventional steps of the soak-shrink technique.

FIG. 2 illustrates a sectional view of a substrate having on its surface an open porosity and a layer of material deposited only at the surface without reaching the inner surface of the pores.

FIG. 3 illustrates a sectional view of a substrate having on its surface an open porosity and a layer of material filling the porosity of the substrate and forming a uniform layer on the surface. FIG. 4 illustrates the different steps implemented according to one embodiment of the invention with the use of the soak-shrink technique. DETAILED DESCRIPTION OF THE INVENTION

By way of example, FIG. 3 illustrates a schematic view of a substrate having on its surface an open porosity 13 and a layer of material 15 filling the porosity of the substrate and forming on the surface an even layer, the layer of material which is obtained by the implementation of the method of the invention.

Whether for the first and second stages of deposition, the first solution as the second solution comprises the constituent ingredients of the electrolytic material and / or precursors of all or part of said ingredients.

Ingredients of the electrolytic material are specified as being the ingredients in the constitution of the electrolytic material forming the layer while the precursor (s) of said ingredients, if any, will require transformation to form said ingredients.

In addition, the first solution and / or the second solution may comprise one or more other ingredients, which are neither ingredients of said material nor precursors of said ingredients.

By way of example, when the first solution and / or the second solution comprise one or more precursors of the one or more ingredients of the material, it may be at least one additive for the transformation of the precursor (s) into the ingredient (s). of said material, such as, for example, polymerization initiators when the precursor (s) are monomers or prepolymers, while the one or more ingredients are polymers.

Moreover, these other ingredients can be organic or aqueous solvents. It is understood that the aforementioned ingredients and precursors are a function of the electrolytic material desired to coat the substrate, further details are provided below.

The method of the invention is intended to obtain a layer of electrolytic material, that is to say a material capable of performing the function of electrolyte, for example, in energy storage devices, such as batteries or capacitors, and which may have a thickness of less than 500 μιη and preferably less than 50 μιη, such an electrolytic material may comprise, for example, an organic or inorganic matrix which will confer the mechanical properties on the material and which comprises, within it, at least one ion-conducting additive (which may be an ion-conducting salt, such as a lithium salt, an ionic liquid or mixtures thereof) and optionally at least one an organic solvent and optionally at least one inorganic additive of the oxide type to enhance the mechanical properties of the material. The first solution and the second solution may include, as ingredients of the electrolytic material or precursors thereof:

one or more polymers for constituting an organic matrix or precursors thereof, such as monomers or prepolymers;

one or more ion-conducting additives selected from ion-conducting salts, ionic liquids or mixtures thereof;

optionally, one or more organic solvents; and

optionally, one or more inorganic additives of the oxides type;

and, in the presence of monomer (s) or prepolymer (s), may comprise a polymerization initiator for converting the monomer (s) or prepolymer (s) into polymer (s)

As examples of polymers that can constitute an organic matrix and can be ingredients of the first solution and the second solution, there may be mentioned polyvinylidene fluorides (PVDF), polymethyl methacrylates (PMMA), polyacrylonitriles (PAN), poly (vinylidene fluoride-co-hexafluoropropylene) copolymers (PVDF-HFP).

As examples of polymer precursors, mention may be made of ethoxylated bisphenol-A dimethacrylate (BEMA), a polyethylene glycol methacrylate (PEGMA), a poly (ethylene glycol) diacrylate (PEGDA), a poly (ethylene glycol) dimethacrylate (PEGDMA), a poly (propylene glycol) diacrylate (PPGDA), a poly (propylene glycol) dimethacrylate (PPGDMA), a poly (ethylene glycol) methyl ether methacrylate (with a molecular weight of poly (ethylene glycol) 300, 500 or 950 g / mol).

As examples of ion-conducting additives, mention may be made of:

- the lithium ion conductive salt, especially when the electrolytic material is intended for a lithium secondary battery, the lithium salt may be LiCl, LiBr, Lil, LiCI0 _4, LiBF _4, Li PF6, LiAsF 6, b / ^'s (fluorosulfonyl) imide lithium (LiFSI), the b / ^'s (trifluorosulfonyl) lithium imide (LiTFSI);

ionic liquids, such as ionic liquids resulting from the combination of a cation chosen from a piperidinium cation, an imidazolium cation, a pyrrolidinium cation, a pyridinium cation, an ammonium cation and an anion chosen from an anion b / ^'s (trifluoromethanesulfonyl) imide, a anion b ^/' s (fluorosulfonyl) imide, acetate anion CH3COO ^", an anion b / ^'s (oxalato) borate B (C ₂ 0 ₄₎ ^2", a bromide anion Br, a chloride anion Cl ^" , anion iodide I ^" , anion tetrachloroaluminate AICI ₄ ^~ , anion hexafluorophosphate PF6 ^~ , anion tetrafluoroborate BF ₄ ^~ , anion dicyanamide N3 ^" , anion (C2H50) HP02 ^~ , anion (CH30 ) HP02 ^~ , a hydrogen sulfate anion HS0 ₄ ^" , a methanesulfonate anion CH3SO3 ^" , a trifluoromethanesulfonate anion

As examples of organic solvents, mention may be made of: carbonate solvents, such as propylene carbonate, ethylene carbonate, dimethyl carbonate and diethyl carbonate;

nitrile solvents, such as succinonitrile, glutaronitrile, butyronitrile;

ester solvents, such as ethyl formate, methyl formate; and

ketone solvents, such as acetone.

As an inorganic oxidic additives examples there may be mentioned particles of Ti0 _2, Si0 _2, MgO, Zr0 _2, AI ₂ u3 of BaTi0 _3.

Finally, when the first solution and / or the second solution comprise at least one polymerization initiator, the latter may be a photoinitiator (or photopolymerization initiator) and, more specifically, a UV photopolymerization initiator, such as 2-hydroxy -2-methyl-l- phenylpropan-l-one (HMPP said, sold under the trademark Darocur ^® 1173), azobisisobutyronitrile (AIBN), 2-dimethoxy-2-phenylacetophenone (DMPA), benzophenone (BP ), p-xylene-b / ^'s (N, N-diethyldithiocarbamate) (XDT).

It is stated above that the electrolytic material may comprise an inorganic matrix. More specifically, it may be a silica matrix. In this case, the first solution and the second solution can comprise one or more silica precursors, such as silicon alkoxide compounds, for example tetraethoxysilane, methyltrimethoxysilane, tetramethylorthosilicate, triethoxysilane and mixtures of these. ci, the other ingredients of the material mentioned above about the electrolytic material comprising an organic matrix (ie, ion-conductive additives, organic solvents, inorganic additives of the oxides type) being valid also for this case. It is understood that these examples of ingredients or precursors are not exhaustive and may be different depending on the coating material that is desired.

The substrate used may be an electrode, for example, positive or negative, said electrode may comprise:

a current-collecting medium, for example, in the form of a metal strip, for example aluminum, copper, nickel, titanium, silver, gold, chromium, tungsten or platinum or an alloy of these ;

- On one side of the current collector support, an active layer comprising the active material of the electrode and optionally an electrically conductive material.

In this case, the active layer mentioned above is a porous layer, which serves as a deposit base for the implementation of the method of the invention.

As examples of active electrode material, mention may be made of lithium intercalation materials that can be used for lithium storage batteries, such materials being able to be chosen from:

the materials of formula wherein MO is chosen from Co, Fe, Ni, M n or of formula LiM20 ₄ in which M is Mn;

the materials of formula LiM _x Mn2 x0 ₄ , in which 0≤x≤0.5 and M is chosen from Ni, Co, Fe, Ti;

the materials of formula LiMPO ₄ , in which M is Fe or

Co;

the material of formula Li ₄ TiO 2.

As examples of electrically conductive material, there may be mentioned carbon black, acetylene black, carbon fibers, carbon nanotubes, metal particles and mixtures thereof. This type of substrate can be obtained by conventional vacuum deposition techniques (PVD, CVD, LPCVD, thermal evaporation) or wet deposition techniques such as those explained below.

Alternatively, the substrate electrode may be directly composed of a material capable of forming an alloy with lithium, such as Bi, Sb, Si, Sn, Zn, Ni, Cd, Ce, Co, Fe, Mg, Ge or capable of forming a defined compound with lithium, such as sulfide compounds or fluoride compounds.

The substrate electrode may finally be a lithium metal electrode, for example, formed of lithium metal fibers.

Finally, the substrate according to different applications of the accumulators may be an insulating substrate, such as a silicon wafer (which may also be designated as a silicon wafer), glass, quartz, a ceramic, a plastic material such as Kapton ^® , Mylar ^® .

As mentioned above, the method of the invention comprises a first step of depositing, wet, on the surface of a substrate, a first solution having a given viscosity. It is understood that the viscosity will be chosen by those skilled in the art so that the solution can be deposited in the porosity of the substrate and / or on the internal surface of the reliefs of the substrate, the appropriate viscosity being determined by preliminary tests. In order to achieve the given viscosity of the first solution, those skilled in the art will be able to play on the nature of the ingredients, for example the use of an organic or aqueous diluent solvent and / or the amount of ingredient and / or the temperature of the first solution.

After the implementation of the first deposition step and before the implementation of the second deposition step, the method may comprise a drying step, so as to allow, where appropriate, the evaporation of all or part of the solvent used in the first deposition step. When the first solution comprises one or more precursors of one or more ingredients intended to constitute the material, the process of the invention may also comprise, after the implementation of the first deposition step and the possible drying step and before the implementation of the second deposition step, a step of converting said precursor (s) into said one or more ingredients.

By way of example, when the precursor (s) are monomers or prepolymers such as those mentioned above, the transformation step is a polymerization step. In particular, taking for example a first solution intended to constitute an electrolytic material and comprising, inter alia, a BEMA monomer and a photoinitiator 2-hydroxy-2-methyl-1,1-phenylpropan-1-one ( HMPP), the polymerization step may consist of UV curing which can use an optimal wavelength of 365 nm for a power of between 3 and 40 mW / cm ² and a dose ranging from 0.2 to 0.5 mWh / cm ² . However, it is understood that, depending on the physico-chemical parameters, particularly in terms of mechanical and electrochemical properties, the dose and power of insolation may vary. For example, at an equivalent dose, a low power and a long deposition time can contribute to promoting good ion conduction properties, while a high power for a short time can promote a good mechanical strength of the material.

By way of example, when the first solution and / or the second solution comprises, as precursors, silica precursors, such as silicon alkoxides, the transformation step is a hydrolysis-condensation step of said precursors.

Finally, after the first deposition step and the possible steps mentioned above, the method of the invention comprises a second step of depositing a second solution having a viscosity greater than the viscosity of the first solution. To achieve this viscosity higher than the viscosity of the first solution, it can be played on at least one of the following factors:

the use of a solvent in a smaller amount than that used in the first solution; and or

the use of a lower temperature compared to that of the first solution; and or

the use of at least one ingredient, such as a salt, in a higher concentration relative to the first solution.

After the implementation of the second deposition step, the method of the invention may comprise a drying step so as to allow, where appropriate, the evaporation of all or part of the solvent used during this step and when the second solution comprises one or more precursors of one or more ingredients intended to constitute the material, the method of the invention may comprise a step of transforming said precursor (s) into said one or more ingredients.

For both the first and second deposition steps, these are carried out wet, that is to say a route involving the use of solutions, the deposition techniques adapted to the process of the invention being be a coating technique, such as the centrifugal coating technique (known as "spin-coating"), the so-called dip-coating technique, spraying technique, such as electrospray (known as "electrospray") and combinations thereof with a preference for soaking-shrinking, for which the process is particularly suitable, knowing that this technique can also be coupled with other techniques such as those explained above.

By way of example, FIG. 4 illustrates the different steps implemented according to one embodiment of the invention with the use of the soak-withdrawal technique with: for part a), a soaking operation consisting in introducing the substrate to be coated into a first coating solution contained in a reservoir and having a predetermined viscosity, the substrate being introduced into the solution at a predetermined soaking rate; ;

- for part b), an immersion operation of leaving the substrate immersed in the first solution (without applying motion to the substrate) for a given duration;

for part c), a removal operation consisting, as its name indicates, of removing the substrate from the first coating solution, this removal being carried out at a predetermined withdrawal speed;

for part d), a dipping-immersion operation of the substrate thus coated in a second coating solution 23 and having a viscosity greater than that of the first solution; and

for part e), a removal operation consisting in removing the substrate from the second coating solution, this removal being carried out at a predetermined withdrawal speed.

For reasons of simplification, for the soaking-removal step involving the second solution, the soaking operation and the immersion operation were shown together in part d) of FIG. 4.

Finally, it should be noted that, in addition to the first and second deposition steps, the method of the invention may comprise other deposition steps according to the characteristics of the material that it is desired to obtain.

Other features and advantages of the invention will emerge from the additional description which follows and which relates to a particular embodiment.

Of course, this additional description is only given as an illustration of the invention and does not in any way constitute a limitation. PARTICULAR EMBODIMENT

This example illustrates the preparation of an electrode-electrolyte assembly and more particularly of a porous electrode coated on one of its faces by a layer of gelled electrolyte produced by the implementation of a method according to the invention. , the deposition substrate being constituted by the electrode.

More specifically, the electrode forming the substrate is composed of a metal current collector, for example an aluminum strip, surmounted by a layer of a composite material comprising a polyvinylidene fluoride (PVDF) polymer matrix in which the active electrode material (here, L1COO2) and an electronically conductive carbonaceous material (here, SuperP carbon black) are dispersed therein. This layer is deposited on the current collector by coating an ink comprising the aforementioned ingredients and an organic solvent, the ink thus deposited being then dried to remove the organic solvent. The resulting layer is then subjected to calendering to obtain a uniform thickness of 17 μιη.

The layer of composite material deposited on the surface of the collector has a porosity of 50% (corresponding to the rate of vacuum in the electrode) with mean pore diameters ranging from 100 nm to 10 μιη determined by electron microscopy, this layer serving as a deposition base for the gelled electrolyte layer.

For the production of this gelled electrolyte layer, two distinct solutions are prepared: a first solution having a low viscosity, of the order of 0.08 Pa.s, and a second solution having a higher viscosity. , of the order of 0.18 Pa.s.

For the realization of the first solution, it is proceeded:

- in a first step, preparing a first mixture comprising 7.68 g of an ionic liquid (b / ^'s (fluorosulfonyl) imide N- propyl-N-methylpyrrolidinium) and 5.12 g of a lithium salt (b / ^'s (fluorosulfonyl) imide lithium) or molar proportions of 1: 1;

- in a second step, adding to the first mixture mentioned above a second mixture comprising two monomers: 2.24 g of ethoxylated bisphenol-A dimethacrylate (BEMA) and 0.96 g of polyethylene glycol methacrylate molar mass 500 g / mol (PEGMA) in 70: 30 mass proportions;

- in a third step, the addition to the resulting mixture of 450 μί of a photopolymerization initiator: Darocur ^® 1173 corresponding to 2-hydroxy-2-methyl-1, 1-phenylpropan-1-one (HMPP) ; and

- In a fourth step, the addition of 4 g of a solvent, methyl formate corresponding to a mass proportion of 20% to fluidize the mixture and pass a viscosity of 1.2 Pa.s to 0.08 Pa.s.

For carrying out the second solution, the procedure is the same as for the first solution, except that the proportion of methyl formate used is less (10% by weight, ie 2 g, instead of 20% mass), so as to obtain a solution having a higher viscosity (0.18 Pa.s for the second solution instead of 0.08 Pa.s for the first solution).

Once the two solutions thus prepared, the electrode defined above is subjected to a first step of soaking-withdrawal with the first solution in the following manner:

- an immersion operation carried out at a speed of

75 mm / min;

- Once the complete immersion of the electrode, an operation of maintaining this immersion for 1 minute; and

a withdrawal operation at a withdrawal speed of

75 mm / min.

After removal, the electrode thus coated is left for 10 minutes in the open air for the methyl formate solvent to evaporate and then the electrode is subjected to UV irradiation at 5 mW / cm ² for 9 minutes to generate the polymerization of the BEMA / PEGMA monomer mixture.

Then the electrode is subjected to a second step of soaking-withdrawal with the second solution in the same manner as those described above for the soaking-removal with the first solution. Once the total shrinkage has been carried out, the electrode thus coated is again subjected to a drying step and to a UV irradiation step as defined above.

This results in an electrode whose layer of composite material is covered with a layer of electrolytic material and, more specifically, a layer of gelled electrolyte, namely an electrolyte comprising a gel resulting from the polymerization of the monomers mentioned above, in this case. its breast, the liquid electrolyte resulting from the mixing of the ionic liquid and the ionic salt mentioned above. The gelled electrolyte layer has a thickness of 2 (35 μιη.

It is also clear from this example, that the first step of soaking-withdrawal with the first less viscous solution allows to route the electrolyte to the core of the composite material and the second step of soaking-withdrawal allows the finalization of the deposit under form of a thick enough surface electrolyte layer to act as solid electrolyte and separator.

Claims

A method of depositing a material in the form of a layer on the surface of a substrate having, on its surface, pores and / or reliefs, said material being an electrolytic material comprising an organic or inorganic matrix comprising within it, at least one ion-conducting additive selected from ion-conducting salts, ionic liquids or mixtures thereof, and optionally at least one organic solvent and optionally at least one oxide-type inorganic additive, said process successively comprising the following steps:

The method of claim 1, wherein the first solution and the second solution comprise, as ingredients of the electrolytic material or precursors thereof:

one or more polymers for constituting the organic matrix or precursors thereof, such as monomers or prepolymers;

optionally, one or more organic solvents; and optionally, one or more inorganic additives of the oxides type.

The method of claim 2, wherein when the first solution and the second solution comprise monomers or prepolymers, they further comprise a polymerization initiator for converting the monomer or prepolymer to polymer.

The method of any one of the preceding claims, wherein the substrate is an electrode.

The method of claim 4, wherein the electrode comprises:

a current collector support in the form of a metal strip;

6. Method according to any one of the preceding claims, comprising, after the implementation of the first deposition step and before the implementation of the second deposition step, a drying step.

7. Method according to any one of the preceding claims, comprising, after the implementation of the first deposition step and the possible drying step and before the implementation of the second deposition step, a step of transforming the or said precursors in said one or more ingredients.

8. Process according to any one of the preceding claims, in which the viscosity of the second solution greater than that of the first solution is obtained by acting on at least one of the following factors:

the use of a lower temperature compared to that of the first solution; and or

the use of at least one ingredient in a higher concentration relative to the first solution.

9. Method according to any one of the preceding claims, comprising after the implementation of the second deposition step, a drying step.

The process according to any one of the preceding claims, wherein the first solution and / or the second solution further comprises at least one additive for converting said precursor (s) into ingredient (s) of said material, when the first solution and / or the second solution comprise one or more precursors of the one or more ingredients of the material.

11. Method according to any one of the preceding claims, comprising after the implementation of the second deposition step, a step of converting said precursor (s) into said one or more ingredients.

The method of any one of the preceding claims, wherein the first and second deposition steps are made by a coating technique, such as the centrifugal coating technique, the soaking-shrinking technique; a spraying technique, such as electrospray; and combinations thereof.

13. The method of any one of the preceding claims, wherein the first and second deposition steps are performed by the soak-shrink technique.