Multilayer electrode-electrolyte components and their production methods

Abstract

The invention relates to multilayer components comprising a solid electrolyte layer and a solid electrode layer, both comprising ceramic particles while being free of polymer as well as to electrochemical cells comprising same. The methods for preparing these multilayer components are also disclosed, which use a hot pressing step.

Description

[0001] MULTILAYER COMPONENTS ELECTRODE-ELECTROLYTE AND THEIR

[0002] MANUFACTURING PROCESSES

[0003] RELATED REQUESTS

[0004] This application claims priority, under applicable law, from U.S. Provisional Patent Applications Nos. 62 / 842,963 and 62 / 955,679 filed on May 3, 2019 and December 31, 2019 respectively, the contents of which are incorporated herein by reference in their entirety and for all purposes.

[0005] TECHNICAL FIELD

[0006] The technical field generally relates to the processes for preparing solid multilayer elements comprising an electrode layer and an electrolyte layer, to the elements obtained by these processes and to the electrochemical cells comprising them.

[0007] STATE OF THE ART

[0008] Liquid electrolytes based on flammable liquids, such as ethylene carbonate or diethyl carbonate, widely used in lithium-ion batteries, can ignite, for example, when the cell temperature rises (Guerfi ​​et al., J. Power Source, 195, 845-852 (2010)) and therefore often lead to unsafe batteries. These liquid electrolytes can also allow the formation of dendrites and necessitate the use of separators with varying degrees of success.

[0009] Solid electrolytes have been developed, for example, based on polymers (mainly based on poly(ethylene oxide), see Commarieu et al., Curr. Opin. Electrochem. 9, 56-63 (2018)) or ceramics such as gallium-doped cubic Li₇La₃Zr₂O₆O₂ (LLZO) (see Rawlence et al., ACS Appl. Mater. Interfaces 10, 13720-13728 (2018)), NAS ICON-type Li₂.sAl₂.sTi₂,5(RO₄)₃ (LATP) (see Soman et al., J. Solid State Electrochem. 16, 1761-1766 (2012)), NASICON-type Li₂,4Al₂,4Gei,e(PO₄)₃ (LAGP) (see Zhang et al., J. Alloys Compd. 590, 147-152 (2014)), and the thio-LISICON LU-xGei- x PxS4 (see Kanno & Murayama, J. Electrochem. Soc. 148, 742-746 (2001)). A hybrid solid electrolyte based on a ceramic and a polymer can also be used to obtain improved mechanical strength and ionic conductivity (Wang et al., ACS Appl. Mater. Interfaces 9, 13694-13702 (2017)).

[0010] The densification of solid electrolytes is a key element in blocking the formation of lithium metal dendrites. Hot pressing has been shown to reduce grain boundary strength in LLZO electrolytes (see David et al., J. Am. Ceram. Soc. 1214, 1209-1214 (2015)). However, the best results reported were obtained at temperatures up to 1100°C. Some groups have reported hot pressing methods for densifying NASICON-type LAGP solid electrolytes. A multi-step process has been described for the densification of LAGP by hot pressing at 600°C under argon at a pressure of 20 MPa followed by a sintering step under air at 800°C for 8 hours to form a LAGP rod (see Kotobuki et al., RSC Ac / v., 11670-11675 (2019)). The rod is then sliced ​​with a diamond wire to provide a thin electrolyte film.

[0011] Nevertheless, the final preparation of a solid-state cathode remains challenging, as sintering a cathode material in the presence of oxygen would likely burn off any carbon present. In 2018, another group described an all-phosphate battery based on Li₃Al₃Ti₃O₇(PO₄)₃ (Yu et al., ACS Appl. Mater Interfaces 10, 22264–22277 (2018)). In this case, the authors prepared an LATP electrolyte pellet by cold pressing followed by sintering at 1100°C under an air atmosphere. The electrolyte layer was then prepared by repeated screen-printing of a suspension composed of LiTi2(PO4)3, Lh.3Al0.3Th.7(PC4)3, carbon black, and ethylcellulose as a binder (45:25:15:15) in NMP as the solvent, followed by drying. The cathode was prepared using the same method, replacing the LiTi2(PO4)3 with LV2(PO4)3.The battery was then subjected to cold isostatic pressing at 504 MPa for 30 seconds and dried again at 120°C.

[0012] Cold sintering processes for the preparation of individual solid electrolytes and solid electrodes were also examined in Liu et al., J. Power Sources 393, 193-203 (2018) using various materials with quite variable results. Therefore, there is a need for new processes for the preparation of solid-state battery components, these processes improving at least some aspect of previous methods.

[0013] SUMMARY

[0014] This document relates to a process for preparing multilayer components and electrochemical cells comprising such components, the multilayer components prepared by this process, the electrochemical cells and batteries comprising them.

[0015] According to one aspect, the process for preparing a multilayer component comprising a solid electrode layer and a solid electrolyte layer includes at least the steps of: a) preparing the solid electrolyte layer by compressing ceramic particles; b) preparing a mixture comprising at least one electrochemically active material, ceramic particles, and an electron-conducting material, the mixture being solvent-free; c) applying the mixture obtained in (b) onto the solid electrolyte layer prepared in (a) to obtain a bilayer material; d) pressing the bilayer material obtained in (c) at a pressure of at least 50 kg / cm² 2 and a temperature in the range of approximately 400°C to approximately 900°C.

[0016] In one embodiment, step (a) excludes the addition of a solvent. In another embodiment, step (a) excludes the addition of a lithium salt. In another embodiment, both the solid electrolyte layer and the electrode layer are polymer-free after step (d). According to yet another embodiment, step (b) also excludes the addition of a solvent. In some embodiments, mixing step (b) is carried out by ball milling. In another embodiment, the ceramic in step (a) has the formula Lh +z AlzlVte- z(PO4)3, in which M is Ti, Ge, or a combination thereof, and z is such that 0 < z < 1. In one embodiment, M is Ge. In another embodiment, M is Ti. According to yet another embodiment, step (a) is carried out in the presence of oxygen (for example, under air). In yet another embodiment, step (a) is carried out at a pressure between 100 kg / cm² 2and 5000 kg / cm² 2 .

[0017] In another embodiment, step (d) is carried out in an inert atmosphere (for example, under argon or nitrogen). In another embodiment, step (d) is carried out at a pressure between 50 kg / cm² 2 and 5000 kg / cm² 2 , or between 100 kg / cm 2 and 5000 kg / cm² 2 , or between 300 kg / cm 2 and 2000 kg / cm 2 In yet another embodiment, step (d) is carried out at a temperature between approximately 450°C and approximately 850°C, or between approximately 600°C and approximately 700°C. In another embodiment, step (d) is carried out for a duration greater than 0 hours and less than 10 hours, or between 30 minutes and 5 hours, or between 30 minutes and 2 hours.

[0018] In one embodiment, the electrode layer is a positive electrode layer. In another embodiment, the electrochemically active material in the electrode layer is selected from phosphates (e.g., LiM₄). a P04 where M a is Fe, Ni, Mn, Co or a combination thereof), oxides and complex oxides such as LiMn2O4, LiM b 02 (M b being Mn, Co, Ni or a combination thereof) and Li(NiM c )02 (M c being Mn, Co, Al, Fe, Cr, Ti, Zr or a combination thereof), elemental sulfur, elemental selenium, iron(III) fluoride, copper(II) fluoride, lithium iodide, and iodine. For example, the electrochemically active material of the positive electrode could be a LiM phosphate. a P04 where M ais Fe, Mn, Co or a combination thereof (e.g. LiFePC), in which said electrochemically active material consists of particles possibly coated with carbon.

[0019] According to other embodiments, the electron-conducting material in the electrode layer is chosen from the group consisting of carbon black, Ketjen black MC , acetylene black, graphite, graphene, carbon fibers or nanofibers (e.g., VGCF), carbon nanotubes and a combination thereof, for example, electron-conducting material includes carbon fibers (such as VGCF).

[0020] In another embodiment, the ceramic particles of step (b) comprise a ceramic of formula Lii +z Al z M2-z(P04)3, where M is Ti, Ge or a combination thereof, and 0 < z < 1. In one example, M is Ge. In another example, M is Ti.

[0021] In one variant of interest, the ceramic of step (a) and the ceramic particles of step (b) are identical.

[0022] According to another aspect, this document relates to a process for preparing a multilayer component comprising a solid electrode layer and a solid electrolyte layer, said process comprising at least the steps of: a) preparing an electrolyte composition layer by spreading a mixture of ceramic and polymer particles onto a first support; b) preparing a mixture comprising at least an electrochemically active material, ceramic particles, an electron-conducting material, and optionally a polymer; c) spreading the electrode material mixture prepared in step (b): i. onto the electrolyte composition layer prepared in (a); or ii. onto a second support followed by contacting a surface of the spread electrode material mixture with a surface of the electrolyte composition layer; to obtain a bilayer material; d) pressing the bilayer material obtained in (c) at a pressure of at least 50 kg / cm²2 and at a temperature between approximately 400°C and approximately 900°C.

[0023] In one embodiment, step (a) of the process excludes the addition of a solvent. Alternatively, step (a) of the process further includes a solvent and also includes drying the mixture after application. In another embodiment, step (a) further includes the removal of the first support. In yet another embodiment, step (a) excludes the addition of a lithium salt. According to one embodiment, the polymer of step (a) and of step (b), if present, is, independently in each instance, selected from a fluorinated polymer (such as poly(vinylidene fluoride) (PVDF) or poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)), a poly(alkylene carbonate) (such as poly(ethylene carbonate) or poly(propylene carbonate)), a poly(vinyl butyral) (PVB), or a polyvinyl alcohol (PVA). For example, the polymer is a poly(alkylene carbonate) (such as poly(ethylene carbonate) or poly(propylene carbonate)).

[0024] According to another embodiment, the solid electrolyte layer and the electrode layer are polymer-free after step (d).

[0025] In another embodiment, the ceramic of step (a) has the formula Lh +z AlzlVte- z(PO4)3, wherein M is Ti, Ge, or a combination thereof, and 0 < z < 1. In one embodiment, M is Ge. In another embodiment, M is Ti. In another embodiment, step (a) further comprises pressing the mixture in the presence of oxygen (e.g., under air), for example, at a pressure between 100 kg / cm² 2 and 5000 kg / cm² 2 .

[0026] In another embodiment, the process includes step (c)(ii) and the process includes removing the first and second supports before contacting the electrode material layer with the solid electrolyte layer. Alternatively, the process includes step (c)(ii) and the process includes removing the first and second supports after contacting the electrode material layer with the solid electrolyte layer.

[0027] In yet another embodiment, the process further includes rolling the bilayer material between rollers before step (d).

[0028] In other embodiments, step (b) further includes a solvent and step (c) further includes drying the spread electrode material. In another embodiment, step (b) includes dry mixing of the electrochemically active material, ceramic particles, and electron-conducting material, suspension of the resulting mixture with a polymer in a solvent, and step (c) further includes drying the spread electrode material.

[0029] In another embodiment, step (d) is carried out in an inert atmosphere (for example, under argon or nitrogen). In another embodiment, step (d) is carried out at a pressure between 50 kg / cm² 2 and 5000 kg / cm² 2 , or between 100 kg / cm 2 and 5000 kg / cm² 2 , or between 300 kg / cm 2 and 2000 kg / cm 2In yet another embodiment, step (d) is carried out at a temperature between approximately 450°C and approximately 850°C, or between approximately 600°C and approximately 750°C. In another embodiment, step (d) is carried out for a duration greater than 0 hours and less than 10 hours, or between 30 minutes and 5 hours, or between 30 minutes and 2 hours.

[0030] In one embodiment, the electrode layer is a positive electrode layer. In another embodiment, the electrochemically active material in the electrode layer is selected from phosphates (e.g., LiM₄). a P04 where M a is Fe, Ni, Mn, Co or a combination thereof), oxides and complex oxides such as LiMn2O4, LiM b 02 (M b being Mn, Co, Ni or a combination thereof) and Li(NiM c )02 (M cbeing Mn, Co, Al, Fe, Cr, Ti, Zr or a combination thereof), elemental sulfur, elemental selenium, iron(III) fluoride, copper(II) fluoride, lithium iodide, and iodine. For example, the electrochemically active material of the positive electrode could be a LiM phosphate. a P04 where M a is Fe, Mn, Co or a combination thereof (such as LiFePC), in which the electrochemically active material consists of particles possibly coated with carbon.

[0031] In other embodiments, the electron-conducting material in the electrode layer is chosen from the group consisting of carbon black, Ketjen black MCacetylene black, graphite, graphene, carbon fibers or nanofibers (e.g., VGCF), carbon nanotubes, and combinations thereof. In one example, the electron-conducting material comprises carbon fibers (such as VGCF). In another example, the electron-conducting material comprises graphite. In yet another embodiment, the ceramic particles in step (b) comprise a ceramic of formula Lii +z Al z M2-z(P04)3, where M is Ti, Ge or a combination thereof, and 0 < z < 1. In one example, M is Ge. In another example, M is Ti.

[0032] According to one variant of interest, the ceramic of step (a) and the ceramic particles of step (b) are identical.

[0033] In another respect, this document relates to a multilayer component obtained by a process as defined herein.

[0034] According to another aspect, the present document relates to a multilayer component comprising a solid electrode layer and a solid electrolyte layer, in which: the solid electrolyte layer comprises ceramic particles; the solid electrode layer comprises an electrochemically active material, ceramic particles, and an electron-conducting material; and the solid electrode layer and the solid electrolyte layer are free of electrolyte polymer and polymer binder.

[0035] In one embodiment, the ceramic in the solid electrolyte layer has the formula Lii +z Al z M2- z (P04)3, where M is Ti, Ge, or a combination thereof, and 0 < z < 1. In one example, M is Ge. In another example, M is Ti.

[0036] In one embodiment, the electrode layer is a positive electrode layer. In another embodiment, the electrochemically active material is selected from phosphates (e.g., LiM₂). a P04 where M a is Fe, Ni, Mn, Co or a combination thereof), oxides and complex oxides such as LiMn2O4, LiM b 02 (M b being Mn, Co, Ni or a combination thereof) and Li(NiM c )02 (M c being Mn, Co, Al, Fe, Cr, Ti, Zr or a combination thereof), elemental sulfur, elemental selenium, iron(III) fluoride, copper(II) fluoride, lithium iodide, and iodine. For example, the electrochemically active material of the positive electrode could be a LiM phosphate. a P04 where M a is Fe, Mn, Co or a combination thereof (such as LiFePC), in which the electrochemically active material consists of particles possibly coated with carbon.

[0037] In another embodiment, the electron-conducting material is chosen from the group consisting of carbon black, Ketjen black MC Acetylene black, graphite, graphene, carbon fibers or nanofibers (e.g., VGCF), carbon nanotubes, and combinations thereof. In one example, the electron-conducting material includes carbon fibers (such as VGCF). In another example, the electron-conducting material includes graphite.

[0038] In yet another embodiment, the ceramic particles in the solid electrode layer comprise a ceramic of formula Lii +z Al z M2-z(P04)3, where M is Ti, Ge, or a combination thereof, and 0 < z < 1. In one example, M is Ge. In another example, M is Ti.

[0039] According to one variant of interest, the ceramic particles in the solid electrolyte layer and the ceramic particles in the solid electrode layer are identical.

[0040] In another embodiment, the multilayer component described herein or prepared by one of the processes described herein comprises a high contact at the interface between the solid electrolyte layer and the solid electrode layer, i.e. an intimately fused interface.

[0041] In yet another embodiment, the multilayer component described herein or prepared by one of the present processes has a high density, for example, where at least one layer of the multilayer component has a density of at least 90% of the theoretical density, for example, the multilayer component has a density of at least 90% of the theoretical density.

[0042] According to another aspect, this document describes an electrochemical cell comprising a negative electrode, a positive electrode, and an electrolyte, wherein the electrolyte and the positive electrode together form a multilayer component as defined herein. In one embodiment, the negative electrode comprises a lithium or lithium alloy film and a polymer intermediate layer between the lithium or lithium alloy film and the solid electrolyte layer. For example, the polymer intermediate layer comprises a polyether polymer and a lithium salt, such as a PEO-based polymer, optionally crosslinked, and a lithium salt (e.g., LiTFSI).

[0043] In another respect, this document concerns a process for preparing an electrochemical cell comprising the steps of:

[0044] (i) preparation of a multilayer component according to a process as defined herein; and

[0045] (ii) assembly of the multilayer component of step (i) with a negative electrode layer.

[0046] In one embodiment, the negative electrode layer comprises a lithium or lithium alloy film and a polymer intermediate layer between the lithium or lithium alloy film and the solid electrolyte layer. For example, the polymer intermediate layer comprises a polyether polymer and a lithium salt, such as a PEO-based polymer, possibly crosslinked, and a lithium salt (such as LiTFSI).

[0047] Another aspect concerns a battery comprising at least one electrochemical cell as defined here, for example a lithium battery or a lithium-ion battery.

[0048] BRIEF DESCRIPTION OF THE FIGURES

[0049] Figure 1 schematically illustrates one embodiment of the present process. Figure 2 shows the X-ray diffraction pattern of (a) LAGP before sintering and (b) LAGP after sintering at 1000°C.

[0050] Figure 3 shows the first two charge / discharge curves of a cell prepared according to an embodiment of the present process when cycled at a current of 100 mA. Figure 4 shows the charge / discharge curves of a cell prepared according to the embodiment described in Example 2.

[0051] DETAILED DESCRIPTION

[0052] The detailed description and examples that follow are illustrative and should not be interpreted as further limiting the scope of the invention.

[0053] All technical and scientific terms and expressions used herein have the same definitions as those commonly understood by a person skilled in the art relating to this technology. However, definitions of certain terms and expressions used are provided below for clarity.

[0054] When the term "approximately" is used here, it means roughly, in the region of and around. When the term "approximately" is used in relation to a numerical value, it modifies it, for example, above and below its nominal value by a variation of 10%. This term can also take into account the probability of random errors in experimental measurements or the rounding of a value.

[0055] The terms "polymer-free," "polymer binder-free," "polymer-exclusive," or "polymer binder-exclusive" are equivalent and mean that the material being characterized, whether it be the electrolyte or an electrode, does not contain any polymer commonly used in electrolytes or as a binder in electrode materials (e.g., a PEO-based polymer, a fluoropolymer, poly(alkylene carbonate), poly(vinyl butyral), polyvinyl alcohol, etc.). However, the term is not intended to exclude carbon-based macromolecules (such as graphene, carbon nanotubes, carbon fibers, etc.) that could serve as electronically conductive materials in electrode materials.

[0056] The term "support" as used here refers to a material, usually in the form of a film or sheet, onto which a mixture, such as a suspension, is applied. The support material does not react with the mixture applied to it. Examples of materials used as supports include polymer supports such as polypropylene, polyethylene, and other inert polymers.

[0057] The term "lithium salt" as used here refers to any lithium salt that can be used in solid electrolytes of electrochemical cells.Non-limiting examples of lithium salts include lithium hexafluorophosphate (LiPFe), lithium bis(trifluoromethanesulfonyl)imidide (LiTFSI), lithium bis(fluorosulfonyl)imidide (LiFSI), lithium 2-trifluoromethyl-4,5-dicyanoimidazolate (LiTDI), lithium 4,5-dicyano-1,2,3-triazolate (LiDCTA), lithium bis(pentafluoroethylsulfonyl)imidide (LiBETI), lithium tetrafluoroborate (L1BF4), lithium bis(oxalato)borate (LiBOB), lithium nitrate (L1NO3), lithium chloride (LiCl), lithium bromide (LiBr), lithium fluoride (LiF), lithium perchlorate (L1ClO4), lithium hexafluoroarsenate (LiAsFe), and lithium trifluoromethanesulfonate. (L1SO3CF3) (LiTf), lithium fluoroalkylphosphate Li[PF3(CF2CF3)3] (LiFAP), lithium tetrakis(trifluoroacetoxy)borate Li[B(OCOCF3)4] (LiTFAB), or bis(1,2-benzenediolato(2-)-0,0')lithium borate Li[B(C6O2)2] (LBBB).

[0058] This document concerns the preparation of solid electrode-electrolyte multilayer components. This process avoids the use of a polymer in the electrolyte or as a binder in the electrode in the final material. Two variants of this process are described here. The first variant does not include a polymer in the preparation of the multilayer, while the second eliminates the polymer used during a hot pressing step. Solvents are generally not required with the first variant of the process. Figure 1 illustrates one embodiment of the process, showing that the solid electrode and electrolyte layers are hot-pressed together.

[0059] While sintering cathode materials at high temperatures under oxygen can lead to combustion of some of the cathode material, LAGP and LATP have been found to be significantly affected when sintered under an inert atmosphere. For these ceramics, gaseous oxygen would then be easily lost, forming impurities of germanium(II) or titanium(II) oxide and lithium phosphate (see Figure 2). This paper therefore presents a new process for preparing components comprising at least two layers, including ceramic-based electrolyte and electrode layers, for use in electrochemical applications. The process is simple and relatively short. One variant also avoids the use of toxic and / or flammable solvents. It also ensures good contact at the interface between the solid electrolyte and electrode layers, where the two layers are intimately bonded (fused) to each other.The solid electrode-electrolyte component also has a suitable density for use in electrochemical cells.

[0060] An example of such a process for preparing a multilayer component includes at least the following steps:

[0061] a) preparation of a solid electrolyte layer by compression of particles comprising a ceramic;

[0062] b) preparation of a mixture comprising at least one electrochemically active material, ceramic particles and an electron-conducting material, the mixture being solvent-free;

[0063] c) application of the mixture obtained in (b) onto the solid electrolyte layer prepared in (a) to obtain a bilayer material;

[0064] d) pressing the bilayer material obtained in (c) at a pressure of at least 50 kg / cm² 2 , or between 50 kg / cm 2 and 5000 kg / cm 2, and at a temperature in the range of about 400°C to about 900°C, or about 450°C to about 850°C, or about 600°C to about 700°C.

[0065] For example, step (a) of the present process avoids the use of solvent and / or lithium salt. The solid electrolyte layer and the solid electrode layer of the resulting component are polymer-free (i.e., solid polymer electrolyte polymer or polymer binder).

[0066] The present process may use any ceramic known to a person skilled in the art, provided the chosen ceramic is suitable as an electrolyte ceramic and stable under the conditions of the present process. For example, the ceramic for the solid electrolyte layer may have the formula Lii +z Al zM2-z(PO4)3, where M is Ti, Ge, or a combination thereof, and z is 0 < z < 1. In one example, M is Ge. In another example, M is Ti. For instance, z lies in the range of 0.25 to 0.75, or 0.1 to 0.9, or 0.3 to 0.7, or 0.4 to 0.6, or is approximately 0.5. The ceramic may have a NASICON-type structure.

[0067] The solid electrolyte layer may have a final thickness (after step (d)) of less than 1 mm, or within the range of 50 pm to 1 mm, or 50 pm to 500 pm, or 50 pm to 200 pm.

[0068] The solid electrolyte layer is preferably compressed in step (a) without external heating and in the presence of oxygen (e.g., under air). The bilayer material, after the addition of the electrode layer mixture, is preferably hot-pressed in step (d) under an inert atmosphere (e.g., under argon or nitrogen).

[0069] For example, step (a) can be carried out at a pressure in the range of 100 kg / cm² 2 at 5000 kg / cm 2 .

[0070] The hot pressing in step (d) can be carried out for a period of more than 0 hours and less than 10 hours, or between 30 minutes and 5 hours, or between 30 minutes and 2 hours. The hot pressing can be performed in a heating chamber such as ovens, furnaces, etc., while applying pressure to at least one side of the bilayer material. Preferably, the hot pressing step is carried out using a hot pressing furnace, a hot pressing die, or similar equipment. The bilayer material is generally contained within a mold, and pressure is applied uniaxially.

[0071] The mixing step (b) in the present process can be carried out by any process known in the art, such as ball milling, planetary mixing, etc. For example, the mixing step can be carried out by ball milling using zirconia (zirconium dioxide) beads. Alternatively, the process for preparing a multilayer component comprising a solid electrode layer and a solid electrolyte layer comprises at least the steps of: a) preparing a solid electrolyte layer by applying a mixture of ceramic and polymer particles to a first support; b) preparing a mixture comprising at least an electrochemically active material, ceramic particles, an electron-conducting material, and optionally a polymer; c) applying the electrode material mixture prepared in step (b): i. onto the solid electrolyte layer prepared in (a); or ii.on a second support followed by contacting a surface of the applied mixture of electrode material with a surface of the solid electrolyte layer; to obtain a bilayer material; d) pressing the bilayer material obtained in (c) at a pressure of at least 50 kg / cm. 2 and at a temperature between approximately 400°C and approximately 900°C.

[0072] Step (a) of the process may exclude the addition of a solvent. Alternatively, step (a) of the process further includes a solvent and a step for drying the mixture after application. In one example, step (a) further includes the removal of the first support. Preferably, step (a) excludes the addition of a lithium salt.

[0073] Non-limiting examples of polymers that may be used in step (a) and possibly in step (b) (if present) include, independently in each instance, a fluoropolymer (such as poly(vinylidene fluoride) (PVDF) or poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)), a poly(alkylene carbonate) (such as poly(ethylene carbonate) or poly(propylene carbonate)), a poly(vinyl butyral) (PVB), or a polyvinyl alcohol (PVA); for example, the polymer is a poly(alkylene carbonate) (such as poly(ethylene carbonate) or poly(propylene carbonate)). The solid electrolyte layer and the electrode layer are polymer-free after step (d).

[0074] The ceramic in step (a) is, for example, of formula Lii +z Al zM2-z(PO4)3, where M is Ti, Ge, or a combination thereof, and z is such that 0 < z < 1. Step (a) may further include pressing the mixture in the presence of oxygen (such as atmospheric oxygen), for example, at a pressure between 100 kg / cm² 2 and 5000 kg / cm² 2 .

[0075] In one example, the process includes step (c)(ii) and involves removing the first and second supports before contacting the electrode material layer with the solid electrolyte layer. Alternatively, the process includes step (c)(ii) and involves removing the first and second supports after contacting the electrode material layer with the solid electrolyte layer.

[0076] Preferably, the process further includes rolling the bilayer material between rollers before step (d).

[0077] In other examples, step (b) further includes a solvent and step (c) further includes drying the applied electrode material. For example, step (b) may include dry mixing of the electrochemically active material, ceramic particles, and electron-conducting material, suspension of the resulting mixture with a polymer in a solvent, followed by drying of the spread electrode material.

[0078] Step (d) can be carried out under an inert atmosphere (e.g., argon, nitrogen). This step can also be carried out at a pressure between 50 kg / cm² 2 and 5000 kg / cm² 2 , or between 100 kg / cm 2 and 5000 kg / cm² 2 , or between 300 kg / cm 2 and 2000 kg / cm 2The temperature applied in step (d) may be in the range of approximately 450°C to approximately 850°C, or approximately 600°C to approximately 750°C. This step is preferably carried out for a duration greater than 0 hours and less than 10 hours, or between 30 minutes and 5 hours, or between 30 minutes and 2 hours. The final thickness of the solid electrolyte layer may be less than 1 mm, or in the range of 50 µm to 1 mm, or from 50 µm to 500 µm, or from 50 µm to 200 µm. The combined thickness of the bilayer material, comprising the electrode layer and the electrolyte, is preferably less than 1 mm, or in the range of 50 µm to 1 mm, or from 50 µm to 600 µm, or from 100 µm to 400 µm.

[0079] In either of the present processes, the electrode layer of the multilayer component is preferably a positive electrode. For example, the electrode layer contains between approximately 25% by weight and approximately 60% by weight of electrochemically active material, between approximately 25% by weight and approximately 60% by weight of ceramic particles, and between approximately 5% by weight and approximately 15% by weight of electron-conducting material, the total being 100%.

[0080] Non-limiting examples of electrochemically active materials include phosphates (such as LiM) a P04 where M a is Fe, Ni, Mn, Co or a combination thereof), oxides and complex oxides such as LiMn2O4, LiM b 02 (M b being Mn, Co, Ni or a combination thereof) and Li(NiM c )02 (M cbeing Mn, Co, Al, Fe, Cr, Ti, Zr or a combination thereof), elemental sulfur, elemental selenium, iron(III) fluoride, copper(II) fluoride, lithium iodide, and iodine. In some examples, the electrochemically active material of the positive electrode is a LiM phosphate. a P04 where M a is Fe, Mn, Co or a combination thereof (such as LiFePC), in which the electrochemically active material consists of particles possibly coated with carbon.

[0081] The electron-conducting material included in the electrode layer can be chosen from carbon black, Ketjen black MC Acetylene black, graphite, graphene, carbon fibers or nanofibers (e.g., VGCF), carbon nanotubes, and combinations thereof. For example, the electron-conducting material includes carbon fibers (such as VGCF) or graphite.

[0082] For example, the ceramic particles in the electrode layer comprise a compound with formula Lii +z Al z M2-z(P04)3, where M is Ti, Ge, or a combination thereof, and 0 < z < 1. In one example, M is Ge. In another example, M is Ti. For instance, z is between 0.25 and 0.75, or z is approximately 0.5.

[0083] According to some examples, the ceramic in the solid electrolyte layer and the ceramic particles in the solid electrode layer comprise the same compound.

[0084] Multilayer components that can be obtained or are obtained by this process are also considered here. For example, multilayer components include an intimately fused interface between the solid electrolyte layer and the solid electrode layer. Both the solid electrolyte layer and the solid electrode layer have a high density. For example, the density of at least one of the two layers is at least 90% of the theoretical density.

[0085] This document also relates to electrochemical cells comprising a negative electrode, a positive electrode, and an electrolyte, where the electrolyte and the positive electrode form a multilayer component as defined herein or obtained by this process. For example, the negative electrode comprises a lithium or lithium alloy film and a polymer intermediate layer between the lithium or lithium alloy film and the solid electrolyte layer. The polymer intermediate layer may comprise, for example, a polyether polymer and a lithium salt, such as a PEO-based polymer, possibly crosslinked, and a lithium salt (e.g., LiTFSI).

[0086] A process for preparing electrochemical cells as defined herein is also envisaged. Such a process includes:

[0087] (i) the preparation of a multilayer component according to a process as defined herein; and

[0088] (ii) assembly of the multilayer component of step (i) with a negative electrode layer. For example, the negative electrode layer comprises a lithium or lithium alloy film and an intermediate polymer layer as described above between the lithium or lithium alloy film and the solid electrolyte layer.

[0089] This description also describes a battery comprising at least one electrochemical cell as defined herein. For example, the battery is a lithium or lithium-ion battery.

[0090] This technology also relates to the use of these batteries and electrochemical cells, for example, in mobile devices, such as mobile phones, cameras, tablets or laptops, in electric or hybrid vehicles, or in renewable energy storage.

[0091] EXAMPLES

[0092] The following non-limiting examples are illustrative embodiments and should not be interpreted as further limiting the scope of the present invention. These examples will be better understood with reference to the accompanying figures.

[0093] Example 1:

[0094] (a) Solid electrolyte-cathode component

[0095] Li₅Al₅Gei₅(PO₄)₃ powder (0.75 g, LAGP) is cold-pressed under air in a 16 mm titanium-zirconium-molybdenum (TZM) mold with a weight of 5 tonnes (5000 kg) to form a LAGP electrolyte pellet. 0.75 g of a mixture containing carbon-coated LiFePC (45 wt.), LAGP (45 wt.), and gas-formed carbon fibers (VGCF, 10 wt.) is added to the LAGP electrolyte pellet to form a bilayer material. This bilayer material is then hot-pressed at 650°C for 1 hour with 2 tonnes (2000 kg) of pressure under an inert atmosphere to obtain the solid electrolyte-cathode component. (b) All-solid-state electrochemical cell

[0096] The solid electrolyte-cathode component obtained in (a) is assembled with a metallic lithium film and a protective layer comprising PEO and lithium bis(trifluoromethanesulfonyl)imidide (LiTFSI) (with an O / Li molar ratio of 20:1) between the metallic lithium anode and the ceramic electrolyte.

[0097] The cell was cycled at 100 mA with charge / discharge results demonstrating 100% efficiency after 50 hours of cycling. Figure 3 shows the potential versus capacity for the first two cycles.

[0098] Example 2: LAGP (85% by weight) and QPAC ®25% (poly(ethylene carbonate), 15% by weight) was dispersed in N,N-dimethylformamide or a 1:1 mixture of N,N-dimethylformamide and tetrahydrofuran. The resulting mixture was spread using a doctor blade onto a polypropylene film. The film was then dried at 50°C for 2 hours. The cathode was prepared by mixing LAGP (45%), LiFePC (45%), and graphite (10%) using a SPEX mixer. ® to obtain a mixed positive electrode material. This mixed positive electrode material (85%) and QPAC ® 25% (15%) were dispersed in N,N-dimethylformamide or a 1:1 mixture of N,N-dimethylformamide and tetrahydrofuran. The resulting mixture was then spread by squeegee onto a polypropylene film. The cathode thus formed was dried at 50°C for 2 hours.

[0099] The self-supporting LAGP electrolyte and cathode films were then separated from the polypropylene films and laminated together at 80°C to reduce porosity and obtain a ceramic-cathode film with a thickness between 100 and 400 µm. The film was then sanded and hot-pressed at 700°C under a pressure of 112 MPa (approximately 1140 kg / cm²). 2 ) for 1 hour. The hot-pressed solid ceramic-cathode electrolyte component was then cycled with metallic lithium and the results are shown in Figure 4.

[0100] Numerous modifications could be made to any of the embodiments described above without departing from the scope of the present invention. All references, patents, or scientific literature cited in this application are incorporated herein in their entirety by reference for all purposes.

Claims

DEMANDS 1. A process for preparing a multilayer component comprising a solid electrode layer and a solid electrolyte layer, said process comprising at least the steps of: a) preparation of the solid electrolyte layer by compression of ceramic particles; b) preparation of a mixture comprising at least one electrochemically active material, ceramic particles and an electron-conducting material, the mixture being solvent-free; (c) application of the mixture prepared in (b) onto the solid electrolyte layer prepared in (a) to obtain a bilayer material; and d) pressing the bilayer material obtained in (c) at a pressure of at least 50 kg / cm² 2 and a temperature in the range of approximately 400°C to approximately 900°C.

2. The process of claim 1, wherein step (a) excludes the addition of a solvent.

3. The process of claim 1 or 2, wherein step (a) excludes the addition of a lithium salt.

4. The method of any one of claims 1 to 3, wherein the solid electrolyte layer and the electrode layer are polymer-free after step (d).

5. The process of any one of claims 1 to 4, wherein the ceramic of step (a) is of formula Lii +z Al z M2-z(P04)3, where M is Ti, Ge, or a combination thereof, and z is such that 0 < z < 1.

6. The method of claim 5, wherein M is Ge.

7. The method of claim 5, wherein M is Ti.

8. The method of any one of claims 1 to 7, wherein step (a) is carried out in the presence of oxygen (e.g., under air).

9. The method of any one of claims 1 to 8, wherein the compression of the particles in step (a) is carried out at a pressure in the range of 100 kg / cm² 2 at 5000 kg / cm 2 .

10. The method of any one of claims 1 to 9, wherein step (d) is carried out under an inert atmosphere (such as argon or nitrogen).

11. The method of any one of claims 1 to 10, wherein step (d) is carried out at a pressure within the range of 50 kg / cm² 2 at 5000 kg / cm 2 , or 100 kg / cm 2 at 5000 kg / cm 2 , or 300 kg / cm 2 at 2000 kg / cm 2 .

12. The method of any one of claims 1 to 11, wherein step (d) is carried out at a temperature in the range of approximately 450°C to approximately 850°C, or approximately 600°C to approximately 700°C.

13. The method of any one of claims 1 to 12, wherein step (d) is carried out for a period of more than 0 hours and less than 10 hours, or between 30 minutes and 5 hours, or between 30 minutes and 2 hours.

14. The method of any one of claims 1 to 13, wherein the preparation of the mixture in step (b) is carried out by ball milling.

15. The method of any one of claims 1 to 14, wherein the electrode is a positive electrode.

16. The process of any one of claims 1 to 15, wherein the electrochemically active material is selected from phosphates (e.g., LiM a P04 where M ais Fe, Ni, Mn, Co or a combination thereof), oxides and complex oxides such as LiMn2O4, LiM b 02 (M b being Mn, Co, Ni or a combination of these), and Li(NiM c )02 (M c being Mn, Co, Al, Fe, Cr, Ti, Zr or a combination thereof)), elemental sulfur, elemental selenium, iron(III) fluoride, copper(II) fluoride, lithium iodide and iodine.

17. The process of claim 16, wherein the electrochemically active material is a phosphate of formula LiM a P04 where M a is Fe, Mn, Co or a combination thereof (e.g., LiFePC), in which said electrochemically active material consists of particles possibly coated with carbon.

18. The method of any one of claims 1 to 17, wherein the electron-conducting material is selected from the group consisting of carbon black, Ketjen black MC, acetylene black, graphite, graphene, carbon fibers or nanofibers, carbon nanotubes and a combination thereof.

19. The process of claim 18, wherein the electron-conducting material comprises carbon fibers (such as VGCF).

20. The process of any one of claims 1 to 19, wherein the ceramic particles of step (b) comprise a ceramic of formula Lii +z Al z M2-z(P04)3, where M is Ti, Ge, or a combination thereof, and 0 < z < 1.

21. The method of claim 20, wherein M is Ge.

22. The method of claim 20, wherein M is Ti.

23. The method of any one of claims 1 to 22, wherein the ceramic of step (a) and the ceramic particles of step (b) are identical.

24. A process for preparing a multilayer component comprising a solid electrode layer and a solid electrolyte layer, said process comprising at least the steps of: a) preparation of an electrolyte composition layer by spreading a mixture of ceramic and polymer particles onto a first support; b) preparation of a mixture comprising at least one electrochemically active material, ceramic particles, an electron-conducting material, and possibly a polymer; c) spreading of the electrode material mixture prepared in step (b): i. on the electrolyte composition layer prepared in (a); or ii. on a second support followed by bringing a surface of the spread electrode material mixture into contact with a surface of the electrolyte composition layer; for obtaining a two-layer material; d) pressing the bilayer material obtained in (c) at a pressure of at least 50 kg / cm² 2 and at a temperature in the range of approximately 400°C to approximately 900°C.

25. The process of claim 24, wherein step (a) excludes the addition of solvent.

26. The process of claim 24, wherein step (a) further comprises a solvent and includes drying the mixture after application.

27. The method of any one of claims 24 to 26, wherein step (a) further comprises the removal of the first support.

28. The process of any one of claims 24 to 27, wherein step (a) excludes the addition of a lithium salt.

29. The process of any one of claims 24 to 28, wherein the polymer of step (a) and of step (b) if present is, independently at each instance, selected from a fluorinated polymer (such as poly(vinylidene fluoride) (PVDF), or poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)), a poly(alkylene carbonate) (such as poly(ethylene carbonate) or poly(propylene carbonate)), a poly(vinyl butyral) (PVB), or a polyvinyl alcohol (PVA).

30. The process of claim 29, wherein the polymer is a poly(alkylene carbonate) (such as poly(ethylene carbonate) or poly(propylene carbonate)).

31. The method of any one of claims 24 to 30, wherein the solid electrolyte layer and the electrode layer are polymer-free after step (d).

32. The process of any one of claims 24 to 31, wherein the ceramic of step (a) is of formula Lii+z Al z M2-z(P04)3, where M is Ti, Ge, or a combination thereof, and 0 < z < 1.

33. The method of claim 32, wherein M is Ge.

34. The method of claim 32, wherein M is Ti.

35. The process of any one of claims 24 to 34, wherein step (a) further comprises pressing the mixture in the presence of oxygen (e.g. under air).

36. The method of claim 35, wherein said pressing is carried out at a pressure in the range of 100 kg / cm² 2 at 5000 kg / cm 2 .

37. The method of any one of claims 24 to 36, wherein said method comprises step (c)(ii) and the method comprises the removal of the first support and the second support before contacting.

38. The method of any one of claims 24 to 36, wherein said method comprises step (c)(ii) and the method comprises the removal of the first support and the second support after contacting and before step (d).

39. The method of any one of claims 24 to 38, wherein the method further comprises a step of rolling the bilayer material between rollers before step (d).

40. The method of any one of claims 24 to 39, wherein step (b) further comprises a solvent and step (c) further comprises drying the spread electrode material.

41. The process of any one of claims 24 to 39, wherein step (b) comprises dry mixing of the electrochemically active material, ceramic particles and electron-conducting material, suspension of the resulting mixture with a polymer in a solvent, and step (c) further comprises drying the spread electrode material.

42. The method of any one of claims 24 to 41, wherein step (d) is carried out under an inert atmosphere (for example under argon, nitrogen).

43. The method of any one of claims 24 to 42, wherein step (d) is carried out at a pressure within the range of 50 kg / cm² 2 at 5000 kg / cm 2 , or 100 kg / cm 2 at 5000 kg / cm 2 , or 300 kg / cm 2 at 2000 kg / cm 2 .

44. The method of any one of claims 24 to 43, wherein step (d) is carried out at a temperature of approximately 450°C to approximately 850°C, or approximately 600°C to approximately 750°C.

45. The method of any one of claims 24 to 44, wherein step (d) is carried out for a period greater than 0 hours and less than 10 hours, or between 30 minutes and 5 hours, or between 30 minutes and 2 hours.

46. The method of any one of claims 24 to 45, wherein the preparation of the mixture in step (b) is carried out by ball milling.

47. The method of any one of claims 24 to 46, wherein the electrode layer is a positive electrode layer.

48. The process of any one of claims 24 to 47, wherein the electrochemically active material is selected from phosphates (such as LiM a P04 where M ais Fe, Ni, Mn, Co, or a combination of two or more of these), the oxides and complex oxides such as LIMr^C, LiM b 02 (M b being Mn, Co, Ni, or a combination thereof), and Li(NiM c )02 (M c being Mn, Co, Al, Fe, Cr, Ti, Zr, or a combination thereof), elemental sulfur, elemental selenium, iron(III) fluoride, copper(II) fluoride, lithium iodide and iodine.

49. The process of claim 48, wherein the electrochemically active material is a phosphate of formula LiM a P04 where M a is Fe, Mn, Co or a combination thereof (e.g. LiFePC), in which the electrochemically active material consists of particles possibly coated with carbon.

50. The method of any one of claims 24 to 49, wherein the electron-conducting material is selected from carbon black, Ketjen black MC, acetylene black, graphite, graphene, carbon fibers or nanofibers, carbon nanotubes and a combination thereof.

51. The process of claim 50, wherein the electron-conducting material comprises carbon fibers (such as VGCF).

52. The method of claim 50, wherein the electron-conducting material comprises graphite.

53. The process of any one of claims 24 to 52, wherein the ceramic particles of step (b) comprise a ceramic of formula Lii +z Al z M2-z(P04)3, where M is Ti, Ge or a combination thereof, and 0 < z < 1.

54. The method of claim 53, wherein M is Ge.

55. The method of claim 53, wherein M is Ti.

56. The method of any one of claims 24 to 55, wherein the ceramic of step (a) and the ceramic particles of step (b) are identical.

57. Multilayer component obtained by the process as defined in any one of claims 1 to 56.

58. Multilayer component comprising a solid electrode layer and a solid electrolyte layer, wherein: the solid electrolyte layer includes ceramic particles; The solid electrode layer comprises an electrochemically active material, ceramic particles, and an electron-conducting material; and The solid electrode layer and the solid electrolyte layer are free of electrolyte polymer and polymer binder.

59. The multilayer component of claim 58, wherein the ceramic in the solid electrolyte layer has formula Lii +z Al z M2-z(P04)3, where M is Ti, Ge, or a combination thereof, and 0 < z < 1.

60. The multilayer component of claim 59, wherein M is Ge.

61. The multilayer component of claim 59, in which M is Ti.

62. The multilayer component of any one of claims 58 to 61, wherein the electrode layer is a positive electrode layer.

63. The multilayer component of any one of claims 58 to 62, wherein the electrochemically active material is selected from phosphates (e.g., LiM a P04 where M a is Fe, Ni, Mn, Co or a combination thereof), oxides and complex oxides such as LiMn2O4, LiM b 02 (M b being Mn, Co, Ni or a combination thereof) and Li(NiM c )02 (M c being Mn, Co, Al, Fe, Cr, Ti, Zr or a combination thereof), elemental sulfur, elemental selenium, iron(III) fluoride, copper(II) fluoride, lithium iodide and iodine.

64. The multilayer component of claim 63, wherein the electrochemically active material is phosphate of formula LiM a P04 where M a is Fe, Mn, Co or a combination thereof (such as LiFePC), in which the material electrochemically active consists of particles possibly coated with carbon.

65. The multilayer component of any one of claims 58 to 64, wherein the electron-conducting material is selected from the group consisting of carbon black, Ketjen black MC , acetylene black, graphite, graphene, carbon fibers or nanofibers, carbon nanotubes and a combination thereof.

66. The multilayer component of claim 65, wherein the electron-conducting material comprises carbon fibers (such as VGCF).

67. The multilayer component of claim 65, wherein the electron-conducting material comprises graphite.

68. The multilayer component of any one of claims 58 to 67, wherein the ceramic particles in the solid electrode layer comprise a ceramic of formula Lii +z Al z M2-z(P04)3, wherein M is Ti, Ge or a combination thereof, and 0 < z < 1.

69. The multilayer component of claim 68, wherein M is Ge.

70. The multilayer component of claim 68, in which M is Ti.

71. The multilayer component of any one of claims 58 to 70, wherein the ceramic particles in the solid electrolyte layer and the ceramic particles in the solid electrode layer are identical.

72. The multilayer component of any one of claims 57 to 71, wherein a high contact area is present at the interface between the solid electrolyte layer and the solid electrode layer.

73. The multilayer component of any one of claims 57 to 72, wherein at least one layer of the multilayer component has a density of at least 90% of the theoretical density.

74. Electrochemical cell comprising a negative electrode, a positive electrode and an electrolyte, wherein the electrolyte and the positive electrode together form a multilayer component as defined in any one of claims 57 to 73.

75. The electrochemical cell of claim 74, wherein the negative electrode comprises a lithium film or a lithium alloy and an intermediate polymer layer between the lithium film or lithium alloy and the solid electrolyte layer.

76. The electrochemical cell of claim 75, wherein the intermediate polymer layer comprises a polyether polymer and a lithium salt, such as a PEO-based polymer optionally crosslinked and a lithium salt (e.g., LiTFSI).

77. Process for preparing an electrochemical cell comprising the steps of: (i) preparation of a multilayer component according to a process as defined in any one of claims 1 to 56; and (ii) assembly of the multilayer component of step (i) with a negative electrode layer.

78. The method of claim 77, wherein the negative electrode layer comprises a lithium or lithium alloy film and an intermediate polymer layer between the lithium or lithium alloy film and the solid electrolyte layer.

79. The process of claim 78, wherein the intermediate polymer layer comprises a polyether polymer and a lithium salt, such as a PEO-based polymer optionally crosslinked and a lithium salt (such as LiTFSI).

80. Battery comprising at least one electrochemical cell as defined in any one of claims 74 to 76.

81. The battery of claim 80, which is a lithium battery or a lithium-ion battery.

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