Metal layer containing penetrating particles of lithium or lithium alloy

Abstract

More specifically, the present invention relates to a metal layer having improved electrochemical properties, comprising through-particles of lithium metal or lithium alloy; a simple and easily industrializable method for manufacturing such a metal layer; the use of such a metal layer as a negative electrode for improving the lifespan of a lithium metal battery; and a lithium metal battery comprising such a metal layer as a negative electrode.

Description

Detailed description of the invention

[0001] The present invention relates particularly to the field of lithium-ion rechargeable batteries used in the manufacture of electric vehicles and / or for the storage of intermittent power such as wind power and / or solar power.

[0002] More specifically, the present invention relates to a metal layer having improved electrochemical properties, comprising through-particles of lithium metal or lithium alloy; a simple and easily industrializable method for manufacturing such a metal layer; the use of such a metal layer as a negative electrode for improving the lifespan of a lithium metal battery; and a lithium metal battery comprising such a metal layer as a negative electrode.

[0003] Lithium metal polymer (or LMP®) batteries currently on the market are generally "all-solid-state" batteries in the form of several-turned thin films or several stacked thin films. This turned or stacked thin film generally includes at least four functional thin films: a negative electrode (anode) that reliably supplies lithium ions during discharge; a positive electrode (cathode) that acts as a receiver into which lithium ions are inserted; a solid polymer electrolyte that conducts lithium ions and is located between the positive and negative electrodes; and a current collector connected to the positive electrode to ensure electrical connection. The negative electrode generally consists of a sheet of lithium metal or lithium alloy; the solid polymer electrolyte generally consists of a polyethylene oxide (PEO)-based polymer and at least one lithium salt; and the positive electrode is usually a metal oxide (e.g., V2O5, LiV3O8, LiCoO2, LiNiO2, LiMn2O4, or LiNi 0.5 Mn 0.5It includes an active electrode material based on O2 (such as) or a phosphate such as LiMPO4 (where M represents a metal cation selected from the group of Fe, Mn, Co, Ni, and Ti, and combinations thereof, and optionally carbon); and the current collector is generally made of a metal sheet. In particular, the presence of a solid polymer electrolyte makes it possible to eliminate the dendrite problem that rapidly develops in conventional separators immersed in liquid electrolytes, such as those used in lithium-ion batteries. In the case of lithium metal batteries, lithium metal (Li 0 A fresh layer of ) is deposited at the anode during charging and then consumed during discharging.

[0004] Currently, the production of lithium metal anodes for all-solid-state batteries involves extruding lithium metal ingots and rolling the extruded lithium to form lithium metal sheets. Specifically, lithium metal ingots are extruded to form coil material with a thickness of approximately 250 μm; the resulting extruded coil material is then placed in a rolling mill. The rolling process can be carried out using a lubricant to obtain the rolled coil material. The thickness of the rolled material is generally in the range of 58 to 72 μm. Current processes for large-scale production of lithium metal anodes have drawbacks, which stem from the very properties of lithium metal, that the rolling lithium metal may react with and / or deform and adhere to the rolling rolls it comes into contact with, and / or from the extreme ductility of lithium or its alloys, which reduces the tensile stress that may be applied to the lithium thin film at the exit of the rolling rolls to prevent the lithium thin film from fracturing or rupturing.

[0005] Furthermore, currently available solid-state lithium metal batteries are still not entirely satisfactory due to their high cost and limited lifespan (or cycle characteristics). In particular, several problems arise related to the use of lithium metal anodes, specifically the process of plating and dissolving the lithium in the anode, and the reactivity between the lithium metal and the battery components, primarily the electrolyte. It is especially known that the practical lifespan of all-solid-state batteries is primarily determined by the degradation of the lithium metal anode.

[0006] Several solutions are believed to overcome the problems associated with the use of lithium metal, including the invention of solid electrolytes with improved mechanical and ionic conductivity, the design and construction of novel anode structures, or the application of protective layers to the surface of lithium metal anodes.

[0007] For example, U.S. Patent Application No. 2021 / 265618 describes a layer disposed at the interface between a lithium metal anode and a solid electrolyte layer, wherein the layer has a specific surface area of ​​500 m² facing the solid electrolyte layer. 2 The boundary layer comprises porous carbon exceeding 1 / g and nanostructures that face the lithium metal anode layer and penetrate the porous carbon. Such boundary layers can be prepared using 3D printing techniques, physical, chemical, or electrochemical deposition methods, but these are complex and expensive. Furthermore, adding an additional layer to the battery can be a drawback when the battery size is to be kept as small as possible.

[0008] In a recent publication, Storelli et al., J. Electrochem. Soc., (USA), 2021, Vol. 168, p. 040505, describes the use of two types of lithium foils with polyethylene oxide (PEO) electrolyte, and it is disclosed that the service life of lithium batteries can be improved by reducing the surface roughness of the lithium foils. In addition, the battery life is further improved by a surface pretreatment of subjecting the lithium foil to a first cycle at a low current density and then significantly increasing the cycle current density. However, this method seems to be difficult to industrialize.

[0009] Therefore, there is a need for a new low-cost technology that enables the improvement of the service life of solid lithium metal batteries, especially one that is easy to implement on an industrial scale.

[0010] The object of the present invention is achieved by a metal layer based on a lithium metal or lithium alloy described hereinafter, as well as by its manufacturing method.

[0011] Specifically, surprisingly, the inventors of the present application have discovered that it is possible to provide a metal layer in the form of through-particles having specific dimensions such that lithium metal or lithium alloy in the metal layer gives the layer a fine structure suitable for improving the service life of lithium batteries.

[0012] The metal layer of the present invention has a homogeneous fine structure that provides improved mechanical and electrochemical properties.

[0013] Therefore, a first main subject of the present invention is a metal layer containing lithium or a lithium alloy, preferably for a lithium metal battery, wherein the metal layer has a thickness e extending in a normal direction D N a width L extending in a transverse direction D T and a length l extending in a rolling direction D L and the directions D N D T and D L are orthogonal to each other, * The metal layer contains through-particles of lithium or a lithium alloy. * Each penetrating particle is in the normal direction D N At least one particle dimension d extending in a direction parallel to the direction GN (μm) and D T and D L At least one particle area S on a plane defined by G (mm 2 ) defined by, * d GN =e(μm), and * S G ≥1.5 × п × [(2.9 × e) / 2] 2 Preferably S G ≥2.0 × п × [(2.9 × e) / 2] 2 , S is particularly preferred G ≥2.5 × п × [(2.9 × e) / 2] 2 , and more preferably S G ≥3 × п × [(2.9 × e) / 2] 2 It is set to be so It is a metal layer characterized by the following:

[0014] The metal layer according to the first subject of the present invention is a single layer, that is, a single layer.

[0015] Normal direction D N Particle dimensions d extending in a direction parallel to the direction GN And, D T and D L Particle area S on a plane defined by G As a result, lithium or lithium alloy particles impart a specific microstructure to the metal layer, leading to superior electrochemical properties.

[0016] In the present invention, the normal direction D N Particle dimensions d extending in a direction parallel to the direction GN This can be measured by microscopy (particularly optical and / or electron microscopy), tomography, or by using a measuring probe, preferably by microscopy (particularly optical and / or electron microscopy).

[0017] In the present invention, the particle area S G Particle area S can be measured by microscopy, particularly optical and / or electron microscopy, in combination with the use of image processing software. G The value corresponds to the average of the 100 particles analyzed.

[0018] In this invention, S G ≥1.5 × п × [(2.9 × e) / 2] 2 Preferably S G ≥2.0 × п × [(2.9 × e) / 2] 2 , S is particularly preferred G ≥2.5 × п × [(2.9 × e) / 2] 2 , and more preferably S G ≥3 × п × [(2.9 × e) / 2] 2 That is the case.

[0019] According to one preferred embodiment of the present invention, the metal layer of the present invention is a self-supporting layer. In other words, the metal layer has sufficient mechanical strength without requiring a support or substrate. According to this preferred embodiment of the present invention, such a metal layer is therefore not deposited on a support or substrate. This also means that the metal layer of the present invention has sufficient electrical conductivity without requiring a current collector when manufacturing a battery comprising such a layer as a negative electrode. According to this preferred embodiment of the present invention, such a metal layer is therefore not deposited on a current collector.

[0020] The thickness e of the metal layer containing lithium or a lithium alloy in the present invention can be 100 μm or less, preferably 90 μm or less, and particularly preferably 80 μm or less. If it exceeds 100 μm, the microstructure of the metal layer does not have a significant impact on improving the cycle characteristics.

[0021] The thickness e of the metal layer is preferably 1 μm or more, particularly preferably 2 μm or more, and even more preferably 5 μm or more.

[0022] In the metal layer, lithium or lithium alloy may constitute at least about 90% by weight relative to the total weight of the metal layer containing lithium or lithium alloy, preferably at least about 95% by weight relative to the total weight of the metal layer containing lithium or lithium alloy, and particularly preferably about 96-99% by weight relative to the total weight of the metal layer containing lithium or lithium alloy.

[0023] According to one particularly preferred embodiment of the present invention, the metal layer is made of lithium or a lithium alloy (i.e., the metal layer contains lithium or a lithium alloy in a weight ratio of approximately 100% of the total weight of the metal layer).

[0024] In the present invention, the penetrating particle is in the normal direction D N At least one particle dimension d extending in a direction parallel to the direction GN Characterized by (μm), d GN = e(μm), where e is the thickness of the metal layer.

[0025] According to one preferred embodiment of the present invention, the metal layer comprises at least 90% by weight, preferably at least 95% by weight, of lithium or lithium alloy penetrating particles, with respect to the total weight of lithium or lithium alloy particles present in the metal layer, and particularly preferably comprises only (i.e., 100%) lithium or lithium alloy penetrating particles.

[0026] Lithium metal refers to lithium (Li) in its oxidation state of zero. 0 This corresponds to ).

[0027] The lithium alloy may be an alloy of lithium with silicon (Si), tin (Sn), aluminum (Al), germanium (Ge), lead (Pb), bismuth (Bi), antimony (Sb), silver (Ag), zinc (Zn), indium (In), magnesium (Mg), and elements selected from a mixture of at least two of the above elements.

[0028] Lithium preferably accounts for at least about 40% by weight, particularly preferably at least about 80% by weight, and more preferably at least about 90% by weight, relative to the total weight of the lithium alloy.

[0029] In one particular embodiment, the penetrating particle has an average estimated diameter d G (μm) ≥ 3.5 × e, preferably d G (μm) ≥ 5 × e. In the metal layer of the present invention, the lithium or lithium alloy particles are larger than those in the lithium-based metal layer of the prior art. This imparts a specific microstructure to the metal layer of the present invention that contributes to improved cycle characteristics.

[0030] In the present invention, the average estimated diameter of the particle is the particle area S as defined above. G Furthermore, by modeling lithium or lithium alloy particles as circular objects, the measurement can be performed. As a result, the average estimated diameter of the particles is given by the following relationship: S G =pl × (d G / 2) 2 [or d G =2 × √(S G / pl)] It can be obtained using

[0031] Since the size and / or area of ​​the lithium or lithium alloy penetrating particles are larger than in the case of the prior art metal layer, the density of the penetrating particles can be reduced. The density of the penetrating particles is determined by the thickness of the metal layer.

[0032] The metal layer according to the present invention preferably has a lithium or lithium alloy penetration particle density (number of particles / mm³). 2 )<151230×(layer thickness, μm) -2Therefore, for a given thickness, the metal layer according to the present invention preferably has a lithium or lithium alloy penetrating particle density lower than the particle density obtained according to Frost's Law (la loi de Frost) (power law versus thin film thickness). In contrast, prior art metal layers obey Frost's Law.

[0033] More specifically, the density of lithium or lithium alloy penetrating particles (number of particles / mm³) 2 )≦101786×(layer thickness, μm) -2 More specifically, the penetration density of lithium or lithium alloy particles (number of particles / mm³) 2 )≦50893×(layer thickness, μm) -2 That is the case.

[0034] The metal layer according to the present invention is preferably in the form of a thin film or foil.

[0035] A second subject of the present invention is a method for producing a metal layer according to the first subject, comprising at least the following steps: - Step i) to prepare a metal laminate containing at least three metal layers including lithium or a lithium alloy, wherein each metal layer contains through-particles of lithium or a lithium alloy and has initial thicknesses ei1, ei2, and ei3, - Step ii) rolling the metal laminate so that the final thickness ef=e of the laminate is ef≦ei1, ef≦ei2, and ef≦ei3. This method is characterized by including [a certain element].

[0036] The method of the present invention makes it possible to form a single metal layer according to the first subject of the present invention from at least three metal layers.

[0037] Step i)

[0038] The method of the present invention is easy to implement, easy to industrialize, and makes it possible to obtain a metal layer having a specific microstructure that results in improved cyclic properties according to the first subject of the present invention, in just a few steps.

[0039] According to one preferred embodiment of the method of the present invention, step i) is step i-1) extruding an ingot of lithium or a lithium alloy and step i-2) rolling to form at least three metal layers comprising lithium or a lithium alloy, and subsequently these metal layers are preferably 0.1 to 1.0 N / mm 2 The process includes step i-3) combining a pressure in the range of 0.5 to 50 m / min and a speed in the range of 0.5 to 50 m / min.

[0040] Thus, each metal layer containing lithium or a lithium alloy is formed by steps i-1) and i-2), and these metal layers are then combined into one for the compounding step i-3).

[0041] Step i-1), which involves extrusion, is preferably carried out at a temperature in the range of 20 to 100°C.

[0042] Step i-2), in which the extruded ingot is rolled, can be performed at a temperature in the range of 20 to 130°C.

[0043] Step i-2), in which the extruded ingot is rolled, can be performed at a speed in the range of 1 to 70 m / min.

[0044] Step i-2), in which the extruded ingot is rolled, can be performed with a load in the range of 5 to 35 kN.

[0045] The rolling process in step i) i-2) is preferably carried out in a rolling mill equipped with at least two working rolls. This allows the extruded ingot to pass between the two rolls.

[0046] Preferably, the rolling process in step i) i-2) is carried out using a lubricant and / or a non-sticky, co-wound thin film.

[0047] This is advantageously added at the entrance of the rolling mill before the extruded ingot passes between the two rolls.

[0048] The lubricant can be selected from volatile siloxanes such as methylsiloxane, and in particular from polydimethylsiloxane, hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, and dodecamethylhexasiloxane.

[0049] Step i-3), which involves compounding at least three metal layers, can be performed at temperatures in the range of 20 to 130°C.

[0050] This compounding step can be performed using a compounding apparatus, which is a machine well known in the prior art and to those skilled in the art.

[0051] At the end of the compounding step, each metal layer of the metal laminate contains through-particles of lithium or lithium alloy, with initial thicknesses ei1, ei2, and ei3.

[0052] Each metal layer of the laminate obtained in step i), i-2), or i-3) contains through-particles. This means that the through-particles in each layer i are in the normal direction D N At least one particle dimension d extending in a direction parallel to the direction GNi Regarding (μm), d GNi This means that the characteristic is that =ei(μm) (where ei is the thickness of the metal layer). In other words, for a laminate comprising three metal layers, each having an initial thickness ei1, ei2, and ei3, the first metal layer is in the normal direction D N At least one particle dimension d extending in a direction parallel to the direction GNi1 (μm) GNi1The second metal layer comprises lithium or lithium alloy penetrating particles characterized by having a diameter of =ei1 (μm), and the normal direction D N At least one particle dimension d extending in a direction parallel to the direction GNi2 (μm) GNi2 The material contains lithium or lithium alloy penetrating particles characterized by having a diameter of =ei2(μm), and the third metal layer is normal to D N At least one particle dimension d extending in a direction parallel to the direction GNi3 (μm) GNi3 It contains lithium or lithium alloy penetrating particles characterized by having a diameter of =ei3 (μm).

[0053] Preferably, at least three metal layers of the metal laminate have substantially the same initial thickness ei1, ei2, and ei3, i.e., the difference in initial thickness is in the range of 0 to 10%.

[0054] At the end of step i), particularly the composite step i-3), the thickness of the metal laminate is 300 μm or less, preferably 250 μm or less, and particularly preferably 200 μm or less.

[0055] The thickness of the metal laminate is generally 30 μm or more.

[0056] In each of the at least three metal layers containing lithium or a lithium alloy obtained at step i-2) or at the end of lamination, the lithium or lithium alloy may constitute at least about 90% by weight of the total weight of the metal layers containing lithium or a lithium alloy, preferably at least about 95% by weight of the total weight of the metal layers containing lithium or a lithium alloy, and particularly preferably about 96-99% by weight of the total weight of the metal layers containing lithium or a lithium alloy.

[0057] The thickness of each of the at least three metal layers containing lithium or a lithium alloy obtained at the end of step i-2) may be 100 μm or less, preferably 90 μm or less, and particularly preferably 80 μm or less.

[0058] The thickness of each of the at least three metal layers containing lithium or a lithium alloy obtained in step i-2) is preferably 1 μm or more, particularly preferably 2 μm or more, and even more preferably 5 μm or more.

[0059] Step II)

[0060] The next step, ii), is to perform a new rolling step to reduce the thickness of the laminate and form a metal layer having a final thickness ef equal to a thickness e as defined in the first subject of the present invention.

[0061] Step ii) is preferably performed with a load f in the range of 5 to 35 kN.

[0062] Step ii) is preferably performed at a speed v in the range of 1 to 70 m / min.

[0063] Step ii) can be performed at a temperature in the range of 20 to 130°C.

[0064] Step ii) is preferably carried out in a rolling mill having at least two working rolls. This allows the laminate to pass between the two rolls.

[0065] Preferably, step ii) is performed using a lubricant and / or a non-sticky, co-winding thin film.

[0066] The lubricant can be selected from volatile siloxanes such as methylsiloxane, and in particular from polydimethylsiloxane, hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, and dodecamethylhexasiloxane.

[0067] This is advantageously preferable to be added at the entrance of the rolling mill before the laminate passes between the two rolls.

[0068] According to one preferred embodiment of the present invention, the final thickness ef is equal to the thinnest of the initial thicknesses ei1, ei2, and ei3.

[0069] A third subject of the present invention is the use of a metal layer obtained by a method according to the first or second subject of the present invention as a negative electrode for improving the cycle characteristics of a lithium metal battery.

[0070] As described above, the metal layer of the present invention has a specific microstructure of lithium or lithium alloy particles that exhibits excellent electrochemical performance, particularly when used as a negative electrode or anode in a lithium metal battery.

[0071] Therefore, the fourth subject of the present invention is: — At least one positive electrode, — At least one negative electrode, — At least one solid or semi-solid electrolyte placed between the positive electrode and the negative electrode It is equipped with, The negative electrode is characterized by being a metal layer obtained by a method according to the first subject of the present invention or the second subject of the present invention. It is a lithium metal battery.

[0072] In the present invention, the "solid or semi-solid" electrolyte is in solid or gel form at room temperature (i.e., a temperature of 18-25°C), preferably in solid form.

[0073] The solid or semi-solid electrolyte of the battery of the present invention preferably comprises one or more polymer materials.

[0074] The polymer material of the solid or semi-solid electrolyte (or, if multiple polymer materials exist) preferably accounts for at least about 30% by weight, and particularly preferably at least about 40% by weight, of the total weight of the solid or semi-solid electrolyte.

[0075] Solid or semi-solid electrolytes are — At least one lithium salt and at least one polyethylene oxide (PEO) polymer material, or — At least one cationic unipolar conductive polymer The polymer electrolyte may contain the following:

[0076] Polyethylene oxide (PEO) polymer materials can be selected from polystyrene-polyethylene oxide (PS-b-PEO) block copolymer, polystyrene-polyethylene oxide-polystyrene (PS-b-PEO-b-PS) block copolymer, poly(ethylene oxide-co-propylene oxide) random copolymer (i.e., PEO-ran-PPO), poly(ethylene oxide-co-butylene oxide) random copolymer (i.e., PEO-ran-PBO), polyethylene oxide, and mixtures thereof.

[0077] Lithium salts used in combination with polyethylene oxide polymer materials include lithium fluorate (LiFO3), lithium bis(trifluoromethanesulfonyl) imidide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium fluoroborate (LiBF4), lithium metaborate (LiBO2), lithium perchlorate (LiClO4), lithium nitrate (LiNO3), lithium bis(fluorosulfonyl) imidide (LiFSI), lithium bis(pentafluoroethylsulfonyl) imidide (LiBETI), LiAsF6, LiCF3SO3, LiSbF6, LiSbCl6, Li2TiCl6, Li2SeCl6, and Li2B 10 Cl 10 Li2B 12 Cl 12 This can be selected from lithium bis(oxalate) borate (LiBOB) and a mixture thereof. The lithium salt is preferably present in a weight ratio of 5-30%, and more preferably 10-25%, of the total weight of the polymer electrolyte.

[0078] The polyethylene oxide (POE) polymer material may be combined with a reinforcing agent. This makes it possible to adjust the mechanical properties of the polymer material.

[0079] The reinforcing agent is preferably selected from cellulose nanofibrils, ceramic nanoparticles such as titanium dioxide, aluminum oxide, or silicon oxide nanoparticles, and fluorinated polymers and copolymers such as polyvinylidene fluoride (PVdF) or vinylidene fluoride-hexafluoropropylene copolymer (PVdF-co-HFP).

[0080] The unipolar conductive polymer may be a polymer (homopolymer or copolymer) comprising at least one organic polymer chain, an organic anionic functional group that forms a covalent bond with the organic polymer chain, and a metal cation (ionically) associated with the organic anionic functional group.

[0081] In this invention, a cationic unipolar conductive polymer means a polymer (homopolymer or copolymer) comprising at least one organic polymer chain, an organic anionic functional group that forms a covalent bond with the organic polymer chain, and a metal cation associated with the organic anionic functional group. These metal cations are chemical species that move and carry out ionic conduction of the polymer.

[0082] The term "organic polymer chain" refers to a polymer chain that does not contain metals or metalloids. In other words, an organic polymer chain either does not contain metals or metalloids such as silicon, or is different from a polysiloxane chain, or does not contain Si-O bonds.

[0083] The term "organo-anionic functional group" refers to an anionic functional group that does not contain metals or metalloids. In other words, an organic-anionic functional group does not contain metals or metalloids such as silicon, nor does it contain Si-O bonds.

[0084] The cationic unipolar conductive polymer of the present invention is a polymer comprising organic anionic repeating units (organic polymer chains and organic anionic functional groups covalently bonded to the organic chains), wherein the organic anionic repeating units are (ionically) associated with metal cations. Cationic unipolar conductive polymers are

[0085] — A homopolymer that can be prepared from monomer a), wherein the monomer comprises at least one organic anionic functional group covalently grafted to the monomer and at least one metal cation associated with the organic anionic functional group; or

[0086] — A copolymer that can be prepared from monomer a) comprising at least one organic anionic functional group covalently grafted to the monomer and at least one metal cation associated with the organic anionic functional group, and monomer b) selected from monomer b1) having at least one other monomer b) different from monomer a) and organic monomer b2) comprising at least one organic anionic functional group covalently grafted and at least one metal cation associated with the organic anionic functional group, and monomer b) That's fine.

[0087] The term "organic monomer b2)" refers to monomers that do not contain metals or metalloids. In other words, organic monomers are compounds that do not contain metals or metalloids such as silicon, and / or contain Si-O bonds.

[0088] The metal cation (of the monomer) or metal cation (of the polymer) associated with the organic anionic functional group is preferably Li + It is a cation.

[0089] Monomer a) or b1), that is, a monomer comprising at least one organic anionic functional group covalently grafted onto the monomer and at least one metal cation associated with the organic anionic functional group, can be selected from aromatic and non-aromatic vinyl monomers that comprise at least one organic anionic functional group covalently grafted onto the organic monomer and at least one metal cation associated with the organic anionic functional group.

[0090] Examples of aromatic vinyl monomers include styrene and its derivatives.

[0091] The styrene derivative is preferably a derivative in which the phenyl portion of styrene is substituted with one or more groups selected from methyl, ethyl, and tert-butyl.

[0092] Examples of non-aromatic vinyl monomers include acrylate, methacrylate, acrylamide, methacrylamide, ethylene, propylene, diene, or maleimide.

[0093] The organic monomer b2) may be vinylidene fluoride, phosphate, phosphonate, ether, carbonate, malonate, amide, acrylate, anhydride, or ester.

[0094] In this embodiment, the copolymer includes repeating units of vinylidene fluoride, phosphate, phosphonate, ether, carbonate, malonate, amide, acrylate, anhydride, or ester, in addition to repeating units of organic anionic repeating units associated with metal cations.

[0095] The organic anionic functional groups of (monomer a) and b1) or (polymer) can be selected from sulfonate, borate, and imidide functional groups.

[0096] The organic anionic functional group is preferably an imidide, particularly preferably a bisulfonylimidide, particularly more preferably a bis(trifluoromethane)sulfonimimidide (TFSI) or a sulfonyl(fluorosulfonyl)imimidide (FSI), and even more preferably a bis(trifluoromethane)sulfonimimidide (TFSI). If the polymer electrolyte contains a cationic unipolar conductive polymer, it is preferable that it does not contain additional lithium salts.

[0097] The aforementioned cationic unipolar conductive polymer can be combined with a reinforcing agent. This makes it possible to adjust the mechanical properties of the polymer.

[0098] The reinforcing agent is preferably selected from cellulose nanofibrils, ceramic nanoparticles such as titanium dioxide, aluminum oxide, or silicon oxide nanoparticles, and fluorinated polymers and copolymers such as polyvinylidene fluoride (PVdF) or vinylidene fluoride-hexafluoropropylene copolymer (PVdF-co-HFP).

[0099] The polymer electrolyte may further contain at least one plasticizer or non-aqueous solvent. This makes it possible to form a gel-like (i.e., gel-like) polymer electrolyte.

[0100] The non-aqueous solvent or plasticizer can be selected from one of the following: linear and cyclic carbonates such as propylene carbonate, ethylene carbonate, or dimethyl carbonate; fluorinated carbonates such as fluoroethylene carbonate; nitriles such as succinonitrile; lactones such as γ-butyrolactone; linear and cyclic polyethers; fluorinated polyethers; sulfur solvents such as sulforane and dimethyl sulfoxide; and mixtures thereof.

[0101] Examples of such non-aqueous solvents or plasticizers include, specifically, dimethyl ether, polyethylene glycol dimethyl ether (or PEGDME) such as tetraethylene glycol dimethyl ether (TEGDME), dioxolane, ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl isopropyl carbonate (MiPC), ethyl acetate, ethyl butyrate (EB), or one of these mixtures.

[0102] Preferably, the solvent or plasticizer is present in a weight ratio of about 10% to 70% of the total weight of the polymer electrolyte, and more preferably in a weight ratio of about 20% to 60%.

[0103] The solid or semi-solid electrolyte is preferably in the form of a thin film.

[0104] Preferably, the thin film of the solid or semi-solid electrolyte has a thickness of 5 to 45 μm, preferably 10 to 25 μm.

[0105] Solid or semi-solid electrolytes can be prepared by any technique well known to those skilled in the art, for example, by coating, extrusion, or compression molding (cold or hot). The positive electrode may include a positive electrode active material, an active material that may produce electronic conductivity, and a polymer material.

[0106] The active material of the positive electrode is a reversible lithium ion active material. In other words, lithium ions can be reversibly inserted into or removed from it.

[0107] The positive electrode active material is: — Metal oxides, for example, vanadium oxide (VO2) x (2≦x≦2.5), LiV3O8, Li y Ni 1-x Co x O2 (0 ≤ x ≤ 1; 0 ≤ y ≤ 1), manganese spinel Li y Mn 1-x M xO2 (M = Cr, Al, V, Ni, 0 ≦ x ≦ 0.5; 0 ≦ y ≦ 2), V2O5, LiCoO2, LiNiO2, LiMn2O4, and LiNi 0.5 Mn 0.5 O2, Li(Ni 1-x-y Mn x Co y )O2, LiNi x CO y Al z O2 (x + y + z = 1), or

[0108] - Phosphosilicate or metal phosphate, such as LiMPO4 (M represents a metal cation selected from the group consisting of one of Fe, Mn, Co, Ni, and Ti, and combinations thereof), such as LiFePO4 or LiMnFePO4, or - Metal sulfate, such as iron sulfate Fe2(SO4)3 can be used. [[ID=​​​​​​​​​​​​​​​​​Polymer materials include homopolymers and copolymers of ethylene, homopolymers and copolymers of propylene; homopolymers and copolymers of ethylene oxide (e.g., PEO, PEO copolymer), methylene oxide, propylene oxide, epichlorohydrin, allyl glycidyl ether homopolymers and copolymers, and mixtures thereof; halogenated polymers, e.g., vinyl chloride, vinylidene fluoride (PVdF), vinylidene chloride, ethylene tetrafluoride or chlorotrifluoroethylene homopolymers and copolymers, vinylidene fluoride and hexafluoropropylene copolymer (PVd Materials may be selected from F-co-HFP) or mixtures thereof; electronically nonconductive anionic polymers, e.g., poly(styrene sulfonate), polyacrylic acid, polyglutamic acid, arginate, pectin, gelatin or mixtures thereof; cationic polymers, e.g., polyethyleneimine (PEI), polyaniline in the form of emeraldine salt (ES), quaternized poly(N-vinylimidazole), poly(acrylamide-diallyldimethylammonium chloride) (AMAC) or mixtures thereof; polyacrylates; lithium salt anion-substituted anionic polymers; and mixtures thereof.

[0114] Lithium salt anion-substituted anionic polymers are as defined in the present invention.

[0115] The polymer material can be, in particular, a polyethylene oxide (PEO)-based polymer material or a lithium salt anion-substituted anionic polymer.

[0116] The active material of the positive electrode can account for approximately 1-25% by weight, preferably approximately 5-20%, of the total weight of the positive electrode.

[0117] According to a particularly preferred embodiment of the present invention, the positive electrode active material is coated with a layer of carbon. The presence of the carbon layer makes it possible to improve the interface:active material-polymer material.

[0118] The amount of carbon coating the active material is preferably approximately 0.1 to 5% by weight relative to the weight of the active material.

[0119] The carbon layer is preferably in the form of a layer with a thickness in the range of approximately 1 to 4 nm.

[0120] The positive electrode may further contain a lithium salt, preferably 1 to 20% by weight of the lithium salt relative to the total weight of the positive electrode, and more preferably 1 to 10% by weight of the lithium salt.

[0121] The lithium salt may be as defined in this invention.

[0122] The positive electrode is preferably in the form of a thin film.

[0123] Preferably, the thickness of the positive electrode is 20 to 100 μm, and more preferably 40 to 50 μm.

[0124] A lithium battery may further include a current collector connected to the positive electrode.

[0125] Current collectors are generally made of metal plates.

[0126] The current collector is preferably made of stainless steel or aluminum, and may be covered with a carbon-based layer (corrosion-resistant layer).

[0127] In the battery according to the present invention, it is preferable that the negative electrode is in direct physical contact with a solid or semi-solid electrolyte. In other words, it is preferable that no intermediate layer is inserted between the negative electrode and the solid or semi-solid electrolyte.

[0128] In the battery according to the present invention, it is preferable that the positive electrode is in direct physical contact with a solid or semi-solid electrolyte. In other words, it is preferable that no intermediate layer is inserted between the positive electrode and the solid or semi-solid electrolyte.

[0129] The present invention is illustrated by the following embodiments, but is not limited to these embodiments.

[0130] The attached drawings illustrate the present invention. [Brief explanation of the drawing]

[0131] [Figure 1] A figure showing a metal layer of the present invention having a thickness e extending in the normal direction DN, a width L extending in the transverse direction DT, and a length l extending in the rolling direction DL, where directions DN, DT, and DL are orthogonal to each other; and penetrating particles of lithium or lithium alloy within the metal layer, defined by a particle dimension dGN (μm) extending in a direction parallel to the normal direction DN, and a particle area SG (mm2) on a plane defined by DT and DL, where dGN = e (μm). [Figure 2] A diagram showing a lithium or lithium alloy penetrating particle with area SG, and a model of the penetrating particle in the form of a circle with an average estimated diameter dG. [Figure 3] A diagram showing the capacity (mAh / g) and efficiency (%) of a battery not according to the present invention, according to the number of cycles. [Figure 4] A diagram showing the internal resistance Ri (ohms·cm²) of a battery not according to the present invention, depending on the number of cycles. [Figure 5] A diagram showing the capacity (mAh / g) and efficiency (%) of the battery according to the present invention, depending on the number of cycles. [Figure 6] A diagram showing the change in internal resistance Ri (ohms·cm²) of the battery according to the present invention, depending on the number of cycles. [Figure 7] A diagram showing the capacity (mAh / g) and efficiency (%) of the battery according to the present invention, depending on the number of cycles. [Figure 8] A diagram showing the change in internal resistance Ri (ohms·cm²) of the battery according to the present invention, depending on the number of cycles.

[0132] [Examples] Unless otherwise specified, all materials described in this specification are used as obtained from the manufacturer.

[0133] <Example 1: Production of Lithium Alloy Thin Film> The lithium metal thin film with a thickness of 18 μm according to the present invention was prepared according to the working conditions described in detail below.

[0134] Three lithium metal layers with a thickness of about 18 μm were obtained by extruding a lithium ingot at a temperature of 30°C and then rolling it at a temperature of 20°C with a rolling speed of 50 m / min and a load of 5 kN.

[0135] Next, these lithium metal layers were combined at a pressure of 0.5 N / mm 2 , a temperature of 60°C, and a speed of 0.5 m / min to form a lithium metal laminate containing three lithium metal layers each with a thickness of 18 μm.

[0136] The lithium metal laminate thus formed was rolled between two rolls at a temperature of 30°C in air (dew point temperature -⁠40°C) with a rolling speed of 2 m / min and a load of 10 kN to form a lithium metal thin film F1 with a thickness of 18 μm.

[0137] A comparative lithium metal thin film F with a thickness of 18 μm, which is not according to the present invention, was prepared according to the working conditions described in detail below. c was prepared according to the working conditions described in detail below.

[0138] One lithium metal layer with a thickness of about 18 μm was obtained by extruding a lithium ingot at a temperature of 30°C and then rolling it at a temperature of 20°C with a rolling speed of 50 m / min and a load of 5 kN to form a lithium metal thin film F c with a thickness of 18 μm.

[0139] Table 1 below shows the characteristics of the fine structures of the two thin films F1 and F thus formed. c formed in this way.

[0140] [Table 1]

[0141] From Table 1, the thin film F for comparison c It can be seen that the area is smaller and the average estimated particle diameter is smaller. More specifically, the thin film F1 according to the present invention is compared to the thin film F c It contains lithium-through-particles with an average estimated diameter 2.5 times larger than lithium-through-particles. Thin film F1 is formed by dynamic recrystallization occurring in steps i) and ii) of the method, resulting in thin film F c It has a different microstructure from that of [another entity]. This dynamic recrystallization can be observed using an optical microscope.

[0142] <Example 2: Manufacturing of batteries from lithium metal thin films>

[0143] A polymer electrolyte containing 50% by weight of poly(vinylidene fluoride) and hexafluoropropylene copolymer sold by Solvay under the reference number "PVdF-HFP 21512", 48% by weight of polyethylene oxide sold by Sumitomo Seika under the reference number "POE 1L", and 12% by weight of LiTFSI sold by Solvay was prepared by extrusion and rolling at 130°C between two silicone-coated PET thin films. A polymer electrolyte film with a thickness of approximately 14 μm was obtained after rolling.

[0144] A positive electrode containing 76% by weight of LiFePO4 (LFP) sold by Sumitomo Osaka Cement, 1% by weight of carbon black sold by Akzo Nobel under the reference number "Ketjenblack EC600JD", 5.5% by weight of LiTFSI sold by Solvay, and 17.5% by weight of POE sold by Sumitomo Seika under the reference number "POE 1L" was prepared by extrusion at 80°C. The resulting mixture was then rolled at 80°C on a coated aluminum current collector sold by Armor to form a positive electrode film.

[0145] After that, the first battery, — Thin film F prepared in Example 1 c The negative electrode consists of, — A polymer electrolyte membrane prepared as described above, and — A positive electrode film prepared as described above It was assembled by continuously combining assemblies formed by [the aforementioned method].

[0146] The composite has a volume of approximately 10 cm³. 3 In a small cell (known as a "pouch cell"), under a pressure of 5 × 10 in air (dew point temperature -40°C) 3 The experiment was conducted in Pa and at a temperature of 80°C.

[0147] Next, to evaluate the electrochemical performance of this first battery, a charge / discharge cycle test was conducted at 80°C using the "Bitrode®" cycle tester, with the charge / discharge method set to C / 10-D / 10 for the first cycle and C / 4-D / 2 for subsequent cycles.

[0148] The results obtained are shown in Figures 3 and 4.

[0149] Figure 3 shows the relative capacity (mAh / g) and efficiency (%) as the number of cycles increases. The gray curve (corresponding arrow) represents the change in capacity, and the black curve (corresponding arrow) represents the change in efficiency.

[0150] Internal resistance (Ri, ohms / cm) depending on the number of cycles 2 The changes in ) are shown in Figure 4.

[0151] The results shown in Figure 3 are for thin film F as the negative electrode. c The efficiency and relative capacity of the battery possessing these features have been demonstrated to remain stable over approximately 520 cycles. Battery efficiency begins to decline around the 400th cycle. In Figure 4, an increase in Ri is observed simultaneously around the 400th cycle (a 32% increase, corresponding to a 0.1% increase in Ri per cycle).

[0152] Next, the second battery... — A negative electrode consisting of a thin film F1 as prepared in Example 1, — A polymer electrolyte membrane prepared as described above, and — A positive electrode film prepared as described above The assemblies formed by these methods were sequentially combined, resulting in the assembly being constructed in exactly the same manner as described above in Example 2.

[0153] The performance of the second battery according to the present invention was compared with the performance of the first battery prepared as described above.

[0154] The conditions for the cycle test were the same as those used for the first battery.

[0155] The results obtained are shown in Figures 5 and 6.

[0156] Figure 5 shows the relative capacity (mAh / g) and efficiency (%) as the number of cycles increases. The gray curve (corresponding arrow) represents the change in capacity, and the black curve (corresponding arrow) represents the change in efficiency.

[0157] Figure 6 shows the internal resistance Ri (ohms·cm) according to the number of cycles. 2 This shows the change in ).

[0158] Figure 5 shows that the cycle characteristics of the second battery according to the present invention are improved compared to those of the first battery. Specifically, the thin film F1 with larger particle size has a cycle characteristic of approximately 770 cycles. The efficiency of the second battery according to the present invention begins to decrease from the 650th cycle. In Figure 6, an increase in Ri is observed simultaneously at approximately the 600th cycle (a 24% increase, corresponding to a 0.05% increase in Ri per cycle).

[0159] Therefore, the functionality of the second battery according to the present invention is improved compared to the functionality of the first battery used for comparison.

[0160] Next, battery 3, — A negative electrode consisting of a thin film F1 as prepared in Example 1, — A gel-like polymer electrolyte containing 70% by weight of a plasticizer (propylene carbonate), 15% of PVdF, and 15% of a cationic unipolar conductive polymer (PSTFSI) (the thickness of the electrolyte membrane is 30 μm). — A cathode film containing 62% by weight of lithium iron manganese phosphate (LMFP), 2.5% carbon black sold by AkzoNobel under reference number "Ketjenblack EC600JD", 30% propylene carbonate, 3.5% PVdF, and 2% cationic unipolar conductive polymer (PSTFSI). The assemblies formed by these methods were sequentially combined, resulting in the assembly being constructed in exactly the same manner as described above in Example 2.

[0161] The cycle test conditions were the same as those used for the first battery, except that the cycle test temperature was 40°C and the charge termination voltage was 4.2V.

[0162] The results obtained are shown in Figures 7 and 8.

[0163] Figure 7 shows the relative capacity (mAh / g) and efficiency (%) as the number of cycles increases. The gray curve (corresponding arrow) represents the change in capacity, and the black curve (corresponding arrow) represents the change in efficiency.

[0164] Figure 8 shows the internal resistance Ri (ohms·cm) according to the number of cycles. 2 This shows the change in ).

[0165] Figure 7 shows that the improved cycle characteristics of the third battery according to the present invention are comparable to those of the second battery. Specifically, the thin film F1 with larger particle size enables a cycle characteristic of approximately 630 cycles at 40°C. The performance of the third battery according to the present invention did not show any decrease or degradation throughout the cycle test.

[0166] In Figure 8, an increase in Ri is observed simultaneously around the 500th cycle (a 17% increase, corresponding to a 0.2% increase in Ri per cycle).

Claims

1. Preferably a metal layer for a lithium metal battery, comprising lithium or a lithium alloy, wherein the metal layer is normal to the direction D Ｎ The thickness e extends in one direction, and the lateral direction D Ｔ The width L that extends in the direction of rolling and the rolling direction D Ｌ It has a length l that extends in the direction D Ｎ , D Ｔ , and D Ｌ They are orthogonal to each other, * The aforementioned metal layer contains through-particles of lithium or a lithium alloy. * Each through-particle extends in a direction parallel to the normal direction D Ｎ by at least one particle dimension d ＧＮ (μm) that extends in a direction parallel to D Ｔ and at least one particle area S Ｌ (mm Ｇ ) on the plane defined by D and D ２ are defined, * d ＧＮ = e(μm), and * S Ｇ ≥ 1.5 × п × [(2.9 × e) / 2] ２ Preferably S Ｇ ≥ 3 × п × [(2.9 × e) / 2] ２ It is set to be so A metal layer characterized by the following:

2. The metal layer according to claim 1, characterized by being self-supporting.

3. The penetrating particle has an average estimated diameter d Ｇ The metal layer according to claim 1 or 2, characterized in that (μm) ≥ 3.5 × e.

4. The metal layer according to any one of claims 1 to 3, characterized in that the thickness e is 100 μm or less.

5. The metal layer has a penetration particle density (number of particles / mm²). ２ )<151230×(layer thickness, μm) －２ A metal layer according to any one of claims 1 to 4, characterized in that it is the metal layer described in any one of claims 1 to 4.

6. The metal layer according to any one of claims 1 to 5, characterized in that the metal layer contains lithium or lithium alloy penetrating particles in a weight ratio of at least 90% of the total weight of lithium or lithium alloy particles present in the metal layer.

7. The metal layer according to any one of claims 1 to 6, characterized in that lithium or lithium alloy accounts for at least 90% by weight relative to the total weight of the metal layer containing lithium or lithium alloy.

8. A method for producing a metal layer as defined in any one of claims 1 to 7, comprising at least the following steps: — A metal laminate containing at least three metal layers, each containing through-particles of lithium or a lithium alloy, wherein the initial thickness is ei １ , ei ２ , ei ３ Step i) prepares a metal laminate, — The metal laminate is rolled so that the final thickness of the laminate ef = e is ef ≤ ei １ , ef≦ei ２ , and ef ≤ ei ３ Step ii) to make it so that A method characterized by including the following.

9. Step i) is an extrusion of a lithium or lithium alloy ingot (step i-1) and a rolling process to form at least three metal layers containing lithium or a lithium alloy (step i-2), followed by rolling these metal layers, preferably at a density of 0.1 to 1.0 N / mm ２ The method according to claim 8, characterized by comprising step i-3) compounding at a pressure in the range of and a speed in the range of 0.5 to 50 m / min.

10. The method according to claim 8 or 9, characterized in that step ii) is performed at a speed v in the range of 1 to 70 m / min.

11. The method according to any one of claims 8 to 10, characterized in that step ii) is performed with a load f in the range of 5 to 35 kN.

12. The method according to any one of claims 8 to 11, characterized in that the thickness of the metal laminate is 300 μm or less.

13. Use as a negative electrode of a metal layer as defined in any one of claims 1 to 7 for improving the cycle characteristics of a lithium metal battery.

14. — At least one positive electrode, — At least one negative electrode, — At least one solid or semi-solid electrolyte placed between the positive electrode and the negative electrode It is equipped with, A lithium metal battery characterized in that the negative electrode is a metal layer as defined in any one of claims 1 to 7.

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