Method for producing electrochemical cells having an energy storage function, and cells produced by means of the method

Abstract

In the claimed method, a metal foil forming a first electrical current conductor is provided with openings, which are distributed uniformly on a surface of the metal foil and are arranged with spacings. The metal foil is subsequently brought into contact with a solid electrolyte, and the metal foil perforated in this way is then provided with a polymer coating, with which the free cross-sectional areas of the openings are filled. A thin, dense solid electrolyte layer is subsequently formed, and a layer forming the cathode is then formed on the opposite surface of the solid electrolyte in relation to the first current conductor, or a cathode is integrally bonded to said surface. The cathode is placed in electrically conductive contact with a further metal foil, which forms a second electrical conductor, on the oppositely arranged surface and is ionically conductively infiltrated with a liquid electrolyte, wherein an alkali metal anode is formed on the solid electrolyte in the region of the openings in the metal foil during charging of said electrochemical cells.

Description

[0001] Fraunhofer Society...eV

[0002] P149800PC00

[0003] Methods for manufacturing electrochemical cells with electrical energy storage function and cells manufactured using the method

[0004] The invention relates to a method for manufacturing electrochemical cells with an electrical energy storage function, as well as to cells manufactured using this method. Such cells are also commonly referred to as batteries (secondary batteries or accumulators) or electrical energy storage devices. They can be charged with electric current by converting it into chemical energy and discharged again for use by an electrical load, with these processes being repeatable cyclically. Conventional electrochemical cells are predominantly constructed with two electrodes and a separator between them, filled with electrolytes. The vast majority of lithium-ion batteries contain liquid, flammable electrolytes, which poses a safety risk during manufacturing and use.Therefore, efforts are underway to replace these liquid electrolytes with non-flammable solid electrolytes, thereby increasing the safety of such electrical energy storage devices.

[0005] For conventional electrochemical cells used for this purpose, their mass / volume, especially in relation to their electrical capacity, plays a significant role, as multiple cells are typically interconnected to store larger amounts of usable electrical energy. The resulting cell weight / volume is particularly disadvantageous in mobile applications.

[0006] The aim is to reduce the energy density of the cells, which is normalized to mass and volume, and to simplify their manufacturing.

[0007] Anode-free alkaline-ion battery concepts have the potential to eliminate the need for an anode layer (e.g., metallic lithium or sodium) in the production of corresponding electrochemical cells. During electrical charging, the anode can be temporarily formed between an electrical conductor and a separator containing electrolyte or a solid electrolyte separator when an electrochemical potential is applied. This occurs when a suitable anode material is released from a chemical compound during charging, accumulates on a surface between the electrical conductor and the electrolyte, and forms a temporary electrode there, acting as the anode.

[0008] Without targeted countermeasures, anode formation would occur in a spatially irregular distribution, leading to inhomogeneous layers due to localization. These inhomogeneous layers, in turn, can cause localized contact losses (delamination, porosity, etc.) during discharge (removal of the anode layer). Frequent (rapid) charging and discharging cycles of such an electrochemical cell intensify this effect, resulting in contact losses (increased electrical resistance of the cell), alkali ion losses (unusable reservoirs of anode material), or the formation of dendrites, ultimately leading to a decrease in capacitance or a short circuit in the cell. At the very least, the usable lifespan and capacity would be significantly reduced.

[0009] The object of the invention is therefore to enable controlled temporary anode formation through suitable construction of electrochemical cells during charging processes of electrochemical cells with safe and effective operation.

[0010] According to the invention, this problem is solved by a method having the features of claim 1. Claim 13 relates to electrochemical cells produced by the method. Advantageous embodiments and further developments of the invention can be realized with features specified in dependent claims.

[0011] The electrochemical cells produced according to the invention differ only slightly in their basic structure from conventionally manufactured cells. They consist of electrical conductors on their two outward-facing surfaces, through which an electric current can flow during charging and discharging. The electric current can flow via ion exchange across electrolytes from one electrode to a complementary electrode, which are separated by a separator. A separator is an ion-conducting but electrically insulating membrane (e.g., made of paper, fabric, or fibrous fleece), which is generally impregnated with an ion-conducting liquid electrolyte. In most cases, this electrolyte consists of lithium or sodium ions.

[0012] In the method according to the invention, a metallic foil forming a first electrical conductor is provided with an insulating thin layer and subsequently with perforations.

[0013] The perforations are evenly distributed across the surface of the metallic foil and spaced between each other at intervals of 100 pm to 500 µm. Each perforation has a free cross-sectional area of ​​approximately 0.03 mm². 2 up to 1 mm 2 and together constitute a proportion of at least 10%, preferably at least 40%, of the surface of the metallic foil which is subsequently brought into contact with a solid electrolyte.

[0014] Metallic foils for electrical conductors can be made of copper, nickel, titanium, or alloys of these or other metals. The use of nickel-containing steels is also possible. The metallic foil for electrical conductors can have a thickness in the range of 10 pm to 150 pm, preferably between 35 pm and 70 pm.

[0015] The solid electrolyte material and the metal of the film forming the first electrical conductor are therefore in contact with each other to a maximum of 90% and 60% respectively.

[0016] The open openings each form a space that can be used to temporarily hold an anode material, usually an alkali metal such as lithium or sodium, during the charging of the respective electrochemical cell. This space should be as locally defined as possible and not distributed uncontrollably across the surface of the thin film that forms the primary conductor. The anode-forming metal is reversibly released during the charging process from a chemical compound that is part of the electrochemical cell and by electrical energy (electrons). ++ e' -> Li). For example, lithium or sodium ions, as a component in the material of the respective cathode, can be released from the corresponding chemical compound during a charging process as a result of the electrochemical reaction and fed through the electrolyte in the separator or solid electrolyte separator, which acts as an ion conductor, to the first electrical conductor, where they are preferentially deposited locally as a metallic phase in the area of ​​perforations. During the discharge process of the electrochemical cell, the corresponding anode metal is converted back into ions by releasing electrons and then passed through the electrolyte again, being incorporated into the original chemical compound.The material used to form a cathode can serve to provide and store sodium or lithium ions. During electrical charging, the Na or Li ions are stored on the opposite side of a solid electrolyte in areas of perforations formed in a primary conductor, where they temporarily serve as the anode of an electrochemical cell. During discharge, this process reverses, and the Na or Li ions permeate the solid electrolyte and are again stored in the cathode until the electrochemical cell is recharged.

[0017] To produce this cell with locally defined depositional areas during anode formation, the perforated metallic foil should be coated with a polymer after perforation. This polymer coating fills the free cross-sectional areas of the perforations, acting as placeholders. The perforations can preferably be created using laser radiation through locally defined ablation of the foil material. Of course, other methods, such as punching, can also be used to create the perforations.

[0018] Following this coating process to fill the perforations, a chemical compound forming a solid electrolyte is applied as a thin layer with a thickness in the range of 5 pm to 50 pm to a surface of the metallic foil. Commonly used, well-established coating processes, in which suspensions containing appropriate powders (e.g., inks, pastes, brines) or solutions / gels are applied to a surface, are also suitable for this purpose. After thermal treatment, this layer should be densified and be electronically insulating but conductive for ions.

[0019] After the material forming the solid electrolyte has been applied as a coating, a thermal treatment (e.g., sintering, densification, or crystallization) is carried out in an inert and / or reducing atmosphere. During this process, the solid electrolyte layer is bonded to a surface, specifically the metallic foil that forms the first conductor. Simultaneously, the organic components, particularly those of the previously applied polymer filling and the coating (which leads to the formation of the solid electrolyte), are driven off. Sintering also results in the densification of the solid electrolyte material.

[0020] Following sintering, a cathode-forming layer is created on the surface of the solid electrolyte opposite the first conductor. Alternatively, a cathode can also be bonded to the solid electrolyte separator at this location.

[0021] The cathode can consist primarily of a chemical compound of sodium (e.g., NaMO₂ layered oxides, spinels, NASICON structures) or lithium (e.g., LÜVIO₂ layered oxides, spinels, olivines) for ion insertion / ejection, and to a lesser extent of an electron conductor (e.g., carbon black). Further additives (e.g., binders, dispersants, plasticizers) may be included to promote adhesion of the cathode layer. For the functionality of the cathode after drying, it is advantageous and highly beneficial if a sodium- or lithium-ion-conducting phase (electrolyte in the cathode, so-called catholyte) is present. Conventional liquid electrolytes (e.g., LiPFe in organic solvents) can be infiltrated for this purpose.

[0022] The cathode is then electrically contacted with another metallic foil on the opposite surface, forming a second electrical conductor.

[0023] An electrochemical cell manufactured in this way can then, in principle, be used as an electrochemical energy storage device.

[0024] It is beneficial to form an oxide barrier layer for ion and electron isolation on the surface of the metallic foil forming the first electrical conductor that faces the solid electrolyte. This barrier layer can be formed with simple or mixed oxides of the elements Li, Na, Al, Zr, Si, or Mg, in particular with Al₂O₃, ZrÜ₂, MgO, SiO₂, ZrSiO₄, or MgAbO₄ (or other insulating thin films). Such a barrier layer can be applied before or after the formation of the perforations. If the electrically conductive metallic support foils consist of alloys, this layer can be created by the targeted pre-oxidation of the electrical conductor. The chemical compound used to form the solid electrolyte should be ionically conductive, especially Na or Li ion conductive. This could be, for example, NasYSi^ or Lii.sAlo.sTii.yfPC h.

[0025] For example, a sol containing dissolved organometallic precursors can be prepared by using water-soluble sodium and yttrose salts (e.g., nitrates, acetates). Tetraethyl orthosilicate (TEOS) can be used as a silicon source. The stoichiometry of the cations (Na:Y:Si = 5:1:4) in the solution can be adjusted so that, after removal of the organic components and sintering, a desired compound consisting of NasYSi4OI2 is formed.

[0026] If Lii.3Alo.3Tii.7(PO4)3 electrolyte is used, it is not stable in contact with metallic lithium. For this reason, a thin (50 nm–500 nm) ion-conducting intermediate layer made of a material that is electrochemically stable with respect to lithium should be applied before the solid electrolyte layer. A compound consisting of Li?La3Zr2OI2 (e.g., via pulsed laser deposition or PLD) can be used for this purpose. Subsequently, a cathode consisting of carbon-coated LiFePO4 and carbon particles, as well as other additives (e.g., binders, dispersants, plasticizers), with a thickness of 50 pm–200 pm (e.g., via screen printing or alternative doctor blade application methods) can be applied to the surface of the electrolyte layer.

[0027] A catalytically active layer on the separator anode side, to reduce resistance to metallic sodium or lithium and to create a locally defined anode in the area of ​​perforations, can be formed with a soluble Pt, Bi, Fe, Sn, Zn, or Pb compound and / or with a carbon layer. Examples of suitable chemical compounds are: Pb acetate, Sn oxalate, and graphene oxide.

[0028] Instead of or in combination with a catalytically active layer, metallic sodium or lithium can also be used directly. For this purpose, sodium or lithium (< 1 pm thick) is directly vapor-deposited onto the electrolyte layer from the back side through the openings of the perforations formed in the first conductor under vacuum.

[0029] The starting materials for a catalytically active layer can also be applied through the openings in the perforations in the metallic foil. The chemical compounds supplied in this way allow the catalytically active layer to form on the solid electrolyte. However, the oxide barrier layer at the interface between the solid electrolyte and the conductor should ideally have formed beforehand. In principle, though, it can form either before or after the perforation has formed.

[0030] The sintering of the solid electrolyte, in which the organic components that had previously been introduced into the perforations by means of the organic coating are also removed, can be carried out in a nitrogen atmosphere, which may also contain a proportion of hydrogen, in the temperature range of 700°C to 1200°C, preferably 800°C to 1100°C.

[0031] If a cathode is formed as a further electrode on a surface of a metallic foil, with which the second electrical conductor of the electrochemical cell is formed, or on a surface of the thermally heat-treated, preferably already sintered solid electrolyte, the cathode material should be formed using thick-film technology with a layer thickness in the range of 50 pm to 200 pm and subsequently at least dried.

[0032] Powdered material in a suspension can also be used for this purpose. NASICON-based materials, such as [example], can be used as cathode materials.

[0033] Use Na3M2(PO4h (M = V, Fe, Ni, Co, Mn,...) or layered oxides of the type NaMÜ2 (M = Mn, Ni, Co, Fe, ...).

[0034] The present invention thus employs a thin perforated metal foil as a substrate, wherein the metal anode formation does not occur at the interface between the metal foil and the solid electrolyte, but rather in the perforated area of ​​the metal foil. This prevents delamination between the solid electrolyte and the electrical conductor. The structures perforated by the openings should have a diameter (lateral dimension) of less than 100 pm (preferably less than 30 pm). The particularly small lateral dimensions of the perforated structures are intended to ensure that the solid electrolyte forms a thin, dense membrane during sintering, covering these areas.

[0035] The invention will be explained in more detail below using an example.

[0036] This shows:

[0037] Figure 1 schematically illustrates a possible procedure for the production of electrochemical cells in 8 steps in this example.

[0038] Starting with a metallic foil for the first conductor, a barrier layer formed with an oxide is created in a second step for ion and electron isolation on a surface of the metallic foil that faces a solid electrolyte to be formed subsequently. In the next step, the perforations are arranged uniformly across the surface of the metallic foil, with no barrier layer present in the inner diameter of the perforations.

[0039] In the next step, the prepared metallic foil is coated with a polymeric coating to fill the gaps in the perforations and prevent the penetration of solid electrolyte material in the following manufacturing steps.

[0040] After the polymer has cured, the material used to form the solid electrolyte can then be applied as a thin layer in the form of a suspension. After drying, this layer undergoes thermal heat treatment in the sixth step. This process removes the organic components, particularly those previously used to fill the openings, resulting in an ion-conducting but electron-impermeable separator layer of solid electrolyte.

[0041] A cathode, serving as an additional electrode, can then be applied directly to the heat-treated solid electrolyte layer, either as a thin layer or as part of a second metallic foil forming the second electrical conductor of the electrochemical cell. This second foil can then be brought into contact with the exposed surface of the solid electrolyte when the electrochemical cell is assembled. The infiltration of a liquid electrolyte into the porous cathode layer completes the production of the electrochemical cell.

[0042] The invention makes it possible to provide metal-supported electrochemical cells formed with an electrical conductor (current collector) and an ultrathin ceramic solid electrolyte.

[0043] The specific examples described below are intended to further improve understanding.

[0044] Example 1

[0045] To manufacture an electrochemical cell, a metallic foil (50–100 pm thick) made of nickel or copper and chemical precursors for the NasYSi^ solid electrolyte to be formed are used. The metallic foil, which forms the first electrical conductor, is coated with a thin film (approx. 10–30 nm) as an oxide barrier layer to prevent the unwanted electrochemical formation of metallic sodium at the interface between the solid electrolyte and the metal. This layer can consist of, for example, Al₂O₃, SiO₂, MgO, or a more complex oxide (e.g., MgAl₂O₄). The coating can be formed using thin-film processes (CVD, PVD, laser ablation, etc.).

[0046] The barrier-coated metal foil is then perforated (e.g., with laser radiation) to create perforations with characteristic lateral dimensions of 15 pm to 50 pm in diameter, spaced 100 pm to 500 pm apart. This forms a perforated metallic foil. The resulting perforations are then filled with a resinous polymer, creating a smooth, closed surface for subsequent coating with the solid electrolyte.

[0047] A suspension is prepared for coating the perforated metallic foil with solid electrolyte. For this, a powder (e.g., NasYSi^ powder with a mean particle size dso of 0.1 pm - 3 pm) is mixed with solvent, binder, plasticizer, and dispersant, and the suspension is adjusted to a suitable viscosity. This suspension is applied to the barrier layer of the perforated metallic foil in a thickness of 10 pm - 30 pm (e.g., by screen printing, dispensing, or wet powder spraying). This creates a homogeneous coating on the perforated and infiltrated primary electrical conductor formed by the perforated metallic foil.

[0048] The electrolyte coating is densified by heat treatment in an inert (N₂) or reducing (N₂ with 2–5% H₂) atmosphere to protect the perforated metallic foil from oxidation. Optionally, the organic components can first be burned off in air at temperatures up to 300 °C to prevent residual carbon in the electrolyte layer. The densification of the electrolyte layer during heat treatment takes place at temperatures of 800–1000 °C. During sintering, the polymer is burned out of the perforated structures, forming a free-standing, thin solid electrolyte membrane on the surface, which acts as a separator. The manufacturing process results in a thin, dense solid electrolyte layer on the surface of the perforated first electrical conductor, exhibiting at least a nearly constant thickness across its entire area.Thickness differences amount to a maximum of 10% in relation to the mean electrolyte layer thickness.

[0049] In this state, a cathode consisting of a suspension with Na3V2(PO4)3 powder, solvent, binder and conductive additive (carbon black) with a thickness of 50 pm - 200 pm (e.g. via screen printing or alternative doctor blade methods) is applied to the surface of the electrolyte layer and dried.

[0050] To facilitate metal deposition on the open electrolyte layer, a catalytically active layer consisting of soluble Sn, Zn, or Pb compounds is applied to the electrolyte surface (accessible through the perforations) from the opposite side via the openings in the metallic foil. This coating creates a thin active layer that promotes the formation of metallic sodium at the interface with the solid electrolyte in the area of ​​the openings when an electrical voltage is applied. Conversely, the barrier layer prevents anode formation between the solid electrolyte and the metal foil. As a result, the anode is formed only locally in the area of ​​the openings, thus preventing delamination between the metal foil (current collector) and the solid electrolyte separator.

[0051] Depending on the composition of the catalytically active layer, the coating can be applied in air or in a glovebox.

[0052] Alternatively, or in addition to such a coating, the electrolyte layer can be coated with metallic sodium (approximately 1 pm thick) by sputtering through the openings in the metallic foil that forms the first electrical conductor, in order to form a catalytically effective layer for electrochemical anode formation.

[0053] Example 2

[0054] In another example, the fabrication of a metal-supported solid electrolyte / metal foil structure (see Figure 1) using liquid precursors for the formation of layers < 2 pm on a perforated metal support is described.

[0055] Similar to embodiment 1, a metallic foil with a thickness of 50 pm to 100 pm is used for the fabrication. The metallic foil forms a first electrical conductor and is provided with a thin film (approx. 10 nm to 30 nm) as an oxide barrier layer to prevent the unwanted electrochemical formation of metallic sodium at the interface between the solid electrolyte and the metal. This oxide barrier layer can consist, for example, of Al₂O₃, SiO₂, MgO, or a more complex oxide (e.g., MgAl₂Ü₄). The oxide barrier layer can also be applied after perforation of the metallic foil.

[0056] In the next step, the metallic foil is perforated (e.g., with laser radiation) so that the perforations in the metallic foil have characteristic lateral dimensions of 15 pm to 30 pm in diameter and are spaced 100 pm to 500 pm apart. This results in a perforated metallic foil. In the following step, the resulting perforations are filled with a polymer, forming a smooth, closed surface for the subsequent coating with the solid electrolyte.

[0057] For coating the perforated metallic foil for the first electrical conductor, a sol containing dissolved organometallic precursors is prepared. Water-soluble sodium and yttrose salts (e.g., nitrates, acetates) can be used for this purpose. Tetraethyl orthosilicate (TEOS) is used as the silicon source. The stoichiometry of the cations (Na:Y:Si = 5:1:4) in the solution is adjusted so that, after removal of the organic components and compaction, a desired compound consisting of NasYSi4OI2 is formed. If the layer thickness after the first coating is insufficient, the coating process can be repeated until a desired layer thickness (>2 pm) is achieved.

[0058] This creates a homogeneous, closed coating of a sodium-conducting solid electrolyte separator on the perforated first electrical conductor.

[0059] The electrolyte coating is densified by heat treatment in an inert (N₂) or reducing (N₂ with 2-4% H₂) atmosphere to protect the perforated metallic foil from oxidation. Optionally, the organic components can first be burned off in air at temperatures up to 300°C to eliminate residual carbon in the layer. The densification of the electrolyte layer during heat treatment occurs during sintering at temperatures in the range of 300°C to 800°C. During sintering, polymeric components are burned out of the perforated structures (openings), forming a free-standing, thin solid electrolyte membrane on the surface. Optionally, the electrolyte layer can be thickened (by approximately 0.5 pm) by thin-film coating using laser ablation, pulsed laser deposition, or other thin-film processes and subjected to a further heat treatment at temperatures up to 800°C.As a result of the manufacturing process, a thin, dense solid electrolyte layer (6) forms on the surface of the perforated current collector.

[0060] In this state, a cathode layer is applied to the surface of the solid electrolyte layer as in Example 1.

[0061] To facilitate metal deposition on the open electrolyte layer, a catalytically active layer consisting of soluble tin, zinc, or lead compounds is deposited onto the free electrolyte surface from the opposite side through the openings in the metallic foil for the first electrical conductor. This catalytically active layer forms a thin active layer that promotes the formation of metallic sodium at the interface with the solid electrolyte during electrical charging of a given electrochemical cell, leading to locally defined anode formation. Depending on the composition of the catalytically active layer, this can be carried out in air or in a glovebox.

[0062] Alternatively, or in addition to such a coating, the opposite side of the cell can be coated in a glovebox with metallic sodium (thickness approx. 1 pm) by sputtering.

[0063] An electrochemical cell produced according to the described manufacturing process is activated on the cathode side by filling the porous cathode structure with the liquid electrolyte (sg catholyte) and is terminated with the second electrical conductor.

[0064] Example 3

[0065] The following describes an exemplary fabrication of a metal-supported electrochemical cell for use in lithium-ion batteries, consisting of a first electrical conductor, a thin ceramic solid electrolyte separator, and a cathode as its essential components. The fabrication of the electrochemical cell utilizes a metallic foil (thickness 50 pm - 100 pm) made of nickel or copper, chemical precursors for Lii.sAlo.sTii.yfPCUh solid electrolyte (powder with a mean particle size dso of 0.1 pm - 3 pm), and sintering aids to lower the sintering temperature of the solid electrolyte (such as U₂CO₃, Li₂BO₂, I₃PO₄, or mixtures thereof). The metallic foil is coated with a thin film (approx. 30 nm - 100 nm) as an oxide barrier layer to prevent the unwanted electrochemical formation of metallic lithium at the interface between the solid electrolyte and the metal.This oxide layer can consist, for example, of Al₂O₃, ZrCh, MgO, or a more complex oxide (e.g., ZrSiO₄ or MgAbO₄). The oxide barrier layer can also be applied after the metallic foil has been perforated.

[0066] In the next step, the metallic foil is perforated (e.g., with laser radiation) so that perforations with characteristic lateral dimensions of 10 pm to 25 pm in diameter, spaced 150 pm to 450 pm apart, are created. This forms a perforated metallic foil. In a subsequent step, the resulting perforations are filled with a polymer, forming a smooth, closed surface for the subsequent coating with the solid electrolyte.

[0067] A suspension is prepared for coating the perforated metallic foil with solid electrolyte. For this, a Lii.3Alo.3Tii.7(PO4)3 powder and sintering aid are mixed with solvent, binder, plasticizer, and dispersant, and the suspension is adjusted to a suitable viscosity. This suspension is applied to the perforated metallic foil in a thickness of 10–30 µm (e.g., by screen printing or wet powder spraying). This results in a homogeneous coating on the perforated and infiltrated first electrical conductor.

[0068] The electrolyte coating is densified by heat treatment in an inert (N₂) atmosphere to protect the perforated metal foil from oxidation. Optionally, the organic components can first be burned off in air at temperatures up to 300°C to prevent residual carbon in the layer. The densification of the electrolyte layer during heat treatment takes place at temperatures of 700°C to 900°C. During sintering, the polymer is burned out of the perforated structures, forming a free-standing, thin solid electrolyte membrane on the surface. The manufacturing process results in a thin, dense solid electrolyte layer on the surface of the perforated first electrical conductor.

[0069] The Lii.3Alo.3Tii.7(PO4)3 electrolyte is not stable compared to metallic lithium. Therefore, a thin (100 nm–500 nm) ion-conducting intermediate layer consisting of an electrochemically stable material (accessible through the perforated openings) must be applied to the sintered layer. A compound consisting of LiyLasZ^O (e.g., via pulsed laser deposition or PLD) can be used for this purpose. Subsequently, a cathode consisting of carbon-coated LiFePO4 powder, conductive additive (carbon black), and binder with a thickness of 50 pm–200 pm (e.g., via screen printing or alternative doctor blade application) is applied to the surface of the electrolyte layer.

[0070] To facilitate electrochemical metal anode deposition on the lithium-protected Lii.3Alo.3Tii.7(P04)3 solid electrolyte, a catalytically active layer consisting of soluble tin compounds is applied to the electrolyte surface (accessible through the perforations in the metallic foil) from the opposite side. This coating forms a thin active layer that promotes the formation of metallic lithium at the interface with the solid electrolyte when an electrical voltage is applied. Depending on the composition of the catalytically active layer, the deposition can be carried out in air or in a glovebox.

[0071] Alternatively, or in addition to such a coating, the opposite side of the cell can be coated with metallic lithium (approximately 2 pm thick) using sputtering in a glovebox. The resulting electrochemical cell is then activated on the cathode side by filling the porous cathode structure, consisting of carbon-coated LiFePC particles and a conductive additive, with the liquid electrolyte (catholyte) and fitted with the second electrical conductor.

Claims

Fraunhofer Society...eV P149800PC00 Patent claims 1. Method for producing electrochemical cells with electrical energy storage functionality in which a metallic foil forming a first electrical conductor is provided with perforations which are uniformly distributed on a surface of the metallic foil and arranged at intervals of 100 pm to 500 pm, and have a free cross-sectional area in the range of 0.03 mm 2 up to 1 mm 2exhibit and constitute a proportion of at least 10%, preferably at least 40%, of the surface of the metallic foil, which is subsequently brought into contact with a solid electrolyte, and the perforated metallic foil is then provided with a polymeric coating with which the free cross-sectional areas of the perforations are filled, and subsequently a thin, dense solid electrolyte layer is formed thereon, and subsequently a layer forming the cathode is formed on the surface of the solid electrolyte opposite the first conductor, or a cathode is metallurgically bonded thereon, and the cathode is electrically contacted with a further metallic foil forming a second electrical conductor on the opposite surface and is ionically infiltrated with a liquid electrolyte.wherein an alkali metal anode is formed on the solid electrolyte in the area of ​​the openings in the metallic foil during the charging of these electrochemical cells.

2. Method according to claim 1, characterized in that a powdered chemical compound forming a solid electrolyte is applied as a thin layer with a layer thickness in the range of 5 pm - 50 pm to a surface of the metallic foil forming the first conductor and is then sintered in an inert and / or reducing atmosphere, in which the solid electrolyte layer is metallurgically bonded to a surface of the metallic foil forming the first conductor and at the same time the organic components are driven off.

3. Method according to claim 1 or 2, characterized in that the thin, dense solid electrolyte layer is applied as a thin layer with a layer thickness in the range of 2 pm - 10 pm via a suspension with dissolved organometallic precursors and is then thermally heat-treated, in particular sintered, in an inert and / or reducing atmosphere, wherein the solid electrolyte layer is metallurgically bonded to a surface of the metallic foil forming the first conductor and the organic components are simultaneously driven out.

4. Method according to one of the preceding claims, characterized in that an oxide barrier layer is formed on the surface of the metallic foil forming the first electrical conductor that points towards the solid electrolyte.

5. Method according to one of the preceding claims, characterized in that a catalytically acting intermediate layer is formed in the area of ​​the perforations on the solid electrolyte for locally defined anode formation in the area of ​​the perforations.

6. Method according to one of the preceding claims, characterized in that the cathode is formed with a chemical compound for providing and for the insertion / removal of sodium or lithium ions.

7. Method according to one of the preceding claims, characterized in that a sodium or lithium ion conducting phase is applied to or introduced into the cathode.

8. Method according to one of the preceding claims, characterized in that a metallic foil with a thickness in the range of 10 pm to 150 pm is used for electrical current conductors.

9. Method according to one of the preceding claims, characterized in that an oxide barrier layer is formed with simple or mixed oxides of the elements Li, Na, Al, Zr, Si or Mg, in particular with Al2O3, ZrÜ2, MgO, SiO2, ZrSiO4 or MgAbO4.

10. Method according to one of the preceding claims, characterized in that a chemical compound forming the solid electrolyte, which is ion-conducting, in particular Na or Li ions, is used.

11. Method according to one of the preceding claims, characterized in that the catalytically active layer is formed with a soluble Sn, Zn or Pb compound or carbon and / or with an alkali metal layer.

12. Method according to one of the preceding claims, characterized in that the solid electrolyte is formed with NasYSi40i2 or Lii.3Alo.3Tii.7(P04)3.

13. Electrochemical cell manufactured by a method according to one of the preceding claims, characterized in that between two electrical conductors formed from metallic foils, in which openings are formed in a metallic foil forming the first electrical conductor, which are arranged at intervals of 100 pm to 500 pm, a free cross-sectional area in the range of 0.03 mm² 2 up to 1 mm 2 exhibit and constitute a proportion of at least 10%, preferably at least 40%, of the surface of the metallic foil, which is subsequently brought into contact with a solid electrolyte, wherein the electrolyte is in the form of a A coating formed solid electrolyte is arranged between a surface of the metallic foil, which forms the first electrical conductor, and a cathode, and is metallurgically bonded, and is contacted on the opposite surface with the metallic foil forming the second electrical conductor.

14. Cell according to claim 13, characterized in that a barrier layer is formed between the metallic foil forming the first electrical conductor and the solid electrolyte.

15. Cell according to claim 13 or 14, characterized in that a catalytically acting intermediate layer is formed in the openings of the metallic foil on the solid electrolyte.

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