Method for producing a solid state cell

Abstract

The invention relates to a method for producing a solid-state cell, in which at least one electrode layer (12, 22) and at least one separator layer (14) are provided, in which a molten and ion-conducting binder is applied to the separator layer (14) and / or to a boundary surface (20) of the electrode layer (12, 22), in which the electrode layer (12, 22) and the separator layer (14) are arranged one on top of the other, and in which the electrode layer (12, 22) and the separator layer (14) are separated from each other. The separating surfaces (20) of the separator layer (14) and the electrode layers (12, 22) are bonded to one another in a cohesive manner to form an ion-conducting adhesive connection.

Description

Technical Field

[0001] The invention relates to a method for producing a solid-state cell, in particular a semi-cell or a single-chamber cell. The invention also relates to a cell component for a solid-state cell, a solid-state cell and a solid-state battery. Background Art

[0002] Electrically or electrically driven or drivable motor vehicles (e.g. electric vehicles or hybrid vehicles) usually include an electric motor, which can drive one or two axles. In order to supply electrical energy, the electric motor is usually connected to a (high-voltage) battery inside the vehicle as an electrical energy storage device.

[0003] Here and below, in particular electrochemical batteries are to be understood to be so-called secondary batteries (secondary batteries) of motor vehicles. In such (secondary) vehicle batteries, the consumed chemical energy can be restored by means of an electrical (re)charging process. Such vehicle batteries are designed, for example, as electrochemical accumulators, in particular lithium-ion accumulators.

[0004] In order to generate or provide a sufficiently high operating voltage, such vehicle batteries usually have at least one battery module (cell module) in which a plurality of individual battery cells are interconnected in a modular manner. Alternatively, a so-called Cell2Pack design is also possible, in which the battery cells are directly connected together, in particular connected in parallel, to form a vehicle battery and are not previously combined into modules.

[0005] The battery cell is implemented, for example, as an electrochemical (thin) layer cell. The thin layer cell has a layered structure with a cathode layer (cathode) and an anode layer (anode) and a separator layer (separator) introduced between the cathode layer and the anode layer. For example, these components are penetrated by a liquid electrolyte (liquid electrolyte), which produces an ion-conducting connection or charge balance of these components. Usually, a plurality of layer cells are arranged one on top of the other to form a cell stack.

[0006] The efficiency of cell production is determined by the manufacturing process and the product structure. One of the most efficient production strategies for conventional thin-layer cells is to manufacture single-chamber cells (single-cells) by means of lamination, and then stack them to form a single-chamber cell stack (single-cell-stack, single-cell-stack) with a final number of layers or layers. In this regard, "lamination" is understood to be the joining of anodes and / or cathodes to one or more laminated diaphragms by the introduction of pressure and temperature. The single-chamber cells thus produced can be implemented, for example, as an anode / diaphragm / cathode / diaphragm-stack or a cathode / diaphragm / anode / diaphragm-stack. Due to the product structure or structure of the single-chamber cells, alternating cell structures can be manufactured by direct stacking.

[0007] With the same structural weight and / or structural volume, a battery cell (hereinafter also referred to as solid cell or solid-state cell) having a solid electrolyte (solid electrolyte, FE) as a separator layer has a higher energy density than a layer cell having a liquid electrolyte. Batteries having solid cells are hereinafter also referred to as solid batteries (FKB) or solid-state batteries.

[0008] In solid-state batteries, (solid, solid-state) electrodes or electrode layers, i.e. cathodes with catholytes or anodes with anolytes (other than lithium metal), are stacked with solid electrolytes (ceramic, glass or glass ceramic) as separators to form a monolayer stack. The anolyte and / or catholyte can consist of a polymer or a ceramic, glass or glass ceramic.

[0009] Disadvantageously, the separator or solid electrolyte in the solid cell is relatively brittle and cannot be locally melted, so that conventional lamination techniques cannot be used to produce the solid cell. Currently there is no continuous production process for producing solid cells - single-chamber cells. Summary of the invention

[0010] The object of the present invention is to describe a particularly suitable method for producing a solid-state cell. In particular, the solid-state cell should be produced as effectively and efficiently as possible. In addition, the object of the present invention is to describe a particularly suitable cell component and a particularly suitable solid-state cell as well as a particularly suitable solid-state battery.

[0011] According to the invention, this object is achieved with respect to the method by the features of claim 1 and with respect to the cell component by the features of claim 4 and with respect to the solid-state cell by the features of claim 6 and with respect to the solid-state battery by the features of claim 7. Advantageous embodiments and improvements are the subject matter of the dependent claims.

[0012] The present invention relates to a novel cell design for solid-state cells, which makes production significantly more efficient. The invention relates in particular to the design of cell components, in particular solid-state semi-cells or sandwich cells or solid-state single-chamber cells (solid-state single-cells) or single-chamber cell stacks, for achieving a production process that is as continuous as possible. However, the production of such semi-cells or single-chamber cells does not take place by heating the cell components, as in conventional lithium-ion cells, but rather by using a molten adhesive.

[0013] A melting adhesive is understood to be an adhesive or bonding agent that is solid in the dry or hardened state and is converted into a liquid state when heated. Therefore, the melting adhesive is especially implemented as a melting adhesive or a hot melt adhesive (hot melt). Here, the melting adhesive preferably has a relatively low melting temperature between 25°C (degrees Celsius) and 50°C, especially between 30°C and 40°C, for example about 35°C. Here, the term "about" especially means a certain temperature range around a given temperature value, for example ±3°. For example, a temperature of about 35° is to be understood as (35±3°), i.e. a temperature range between 32°C and 38°C.

[0014] Here and in the following, a (solid) semi-cell (solid-state semi-cell) is to be understood in particular as a cell component having only two cell layers or cell stacks. A cell layer or cell stack is to be understood as a cut or cut-to-size (electrode / diaphragm) sheet. In this case, a cell layer has an electrode layer (i.e. a solid electrode or solid electrode, for example a cathode layer or an anode layer) and a diaphragm layer (i.e. a solid electrolyte). The electrode layers and the diaphragm layers are arranged one on top of the other. With regard to cell production, a semi-cell forms the smallest structural unit or cell component.

[0015] In this case, the electrode layer comprises, for example, an (electrode) active material, a binder, conductive carbon black and a solid electrolyte. As an active material, the electrode layer comprises, for example, an anode active material or a cathode active material.

[0016] For the anode, for example, graphite (Grafit) or a lithium alloy material such as silicon (Si), zinc (Sn), or lithium titanate is used. For example, the anode can also be formed only by a current collector (copper / aluminum), on which lithium can be deposited. In this case, the current collector can also be coated, for example, the current collector can have a nickel coating.

[0017] In the case of the cathode, in particular: lithium transition metal oxides with different stoichiometric ratios, such as NMC (lithium nickel manganese cobalt oxide) or LMNO (lithium manganese nickel oxide); LFP (lithium iron phosphate) or other phosphates, such as LMP (lithium metal polymer). As conductive additives, for example (conductive) carbon black, graphene, carbon nanotubes (CNT) in single-wall (SWCNT) or multi-wall (MWCNT) embodiments or combinations thereof can be used.

[0018] As a separator material for the separator layer, for example, LLZO (lithium lanthanum zirconium oxide) or LATP (aluminum lithium titanium phosphate) and derivatives thereof can be used.

[0019] Here and below, the next larger structural unit or cell component is also referred to as a sandwich cell. A sandwich cell has three cell layers. In this case, either an electrode layer is arranged in a sandwich manner between two separator layers, or a separator layer is arranged in a sandwich manner between two electrode layers of different polarity, i.e., between an anode layer and a cathode layer.

[0020] Here and below, a (solid-state) single-chamber cell (solid-state single-chamber cell) is to be understood in particular as an arrangement of two half-cells with different polarities. This means that one half-cell has an anode layer and the other half-cell has an electrode layer with a cathode layer. For example, the single-chamber cell is designed as an anode / diaphragm / cathode / diaphragm stack or a cathode / diaphragm / anode / diaphragm stack.

[0021] Here and in the following, a single-chamber cell stack is to be understood in particular as a directly alternating arrangement of a certain number of single-chamber cells (i.e. at least two single-chamber cells), whereby anode layers and cathode layers are arranged alternately in the cell stack along the stacking direction, wherein the electrode layers are respectively separated from one another by separator layers.

[0022] The method according to the invention is provided and is suitable for and is designed for producing solid cells, in particular cell components (e.g. half cells, sandwich cells or single-chamber cells or single-chamber cell stacks). According to the method, at least two cell layers or cell stacks are provided. In particular, at least one electrode layer and at least one separator layer are provided. According to the invention, a molten and ion-conducting adhesive is applied to at least one of the interfaces of the separator layer and / or the electrode layer. In particular, the adhesive is melted and applied to the interface in a liquid state.

[0023] Next, the electrode layers and the separator layers are stacked one on top of the other, wherein the mutually abutting interfaces of the separator layers and the electrode layers are bonded to one another in a materially bonded manner while forming an ion-conducting adhesive bond (bonding connection). The liquid adhesive is then cured, thereby mechanically and electrically bonding the separator layers to the electrode layers.

[0024] This results in a particularly suitable method for producing solid-state cells. In particular, the method enables simple and reliable production of solid-state semi-cells, sandwich cells and single-chamber cells, wherein the use of a molten and ion-conducting adhesive provides a particularly advantageous product structure and product strategy for producing purely solid-state cells.

[0025] According to the invention, the adhesive should only ensure the adhesive strength during assembly (stacking of the cell cells). In the subsequent battery operation, the remelting of the adhesive is not important, because the cell stack cannot slide against each other due to the expansion of the cell stack in the cell housing (cell breathing) during the charging process, in which the battery cells are charged with electrical energy and simultaneously generate heat. Thus, the molten adhesive essentially only makes the production of the battery cells more efficient.

[0026] Preferably, the method first manufactures half cells and single-chamber cells, and then directly stacks the single-chamber cells to produce a single-chamber cell stack as a cell stack of solid cells, thereby achieving an improvement and increase in efficiency in a cell production line for solid cells.

[0027] In one conceivable embodiment, the interface between cathode layer and separator layer is bonded, in particular, by means of a fusible and ion-conducting adhesive. Here, the anode-sandwich cell can also be formed, for example, by a composite film consisting of separator / anode / separator.

[0028] Here and in the following, "material fit" or "material fit connection" between at least two interconnected components is understood in particular to mean that the interconnected components are held together at their contact surfaces by material bonding or crosslinking (e.g. due to atomic or molecular bonding forces), optionally with the action of additives.

[0029] Due to manufacturing reasons, not only the electrode layer but also the separator layer has at least a certain surface roughness. However, in solid cells, for good charge transport, it is necessary that the contact between the cell layers (that is, especially between the electrode layer and the separator layer) is as close as possible. However, due to the roughness of the surface, it is often not possible to achieve a completely surface contact between the two cell layers. In addition to a better production design, the application of an ion-conducting adhesive also advantageously leads to a reduction in the interface resistance between the separator and the anode / cathode. In addition, the adhesive compensates for unevenness in the boundary layer, which in turn leads to improved uniformity and, as a result, to improved electrochemical properties of the finished solid cell. Here, the adhesive layer is implemented as thin as possible so as not to adversely reduce the volume capacity of the battery cell. For example, the applied adhesive layer has a layer thickness of between 0.1 μm (micrometer) and 10 μm.

[0030] In a preferred embodiment, the adhesive comprises ethylene carbonate (EC). In other words, an adhesive is used which comprises EC and which is nevertheless able to conduct ions and to join the necessary components (electrode layers / diaphragm layers). EC has a relatively low melting point, which enables particularly simple application.

[0031] In a particularly preferred embodiment, EC is used as the melting adhesive. In other words, the adhesive is essentially formed by EC. The proportion of EC in the adhesive is greater than 50 Gew-% (weight percentage), in particular greater than 75 Gew-%, for example greater than 90 Gew-%. EC has a melting point of 37° C. and is therefore particularly suitable for the method described above.

[0032] The advantages and designs mentioned in view of the method can also be appropriately transferred to the cell component according to the present invention, and vice versa. The cell component according to the present invention is configured and suitable for and is set up for producing a solid cell. The cell component has at least one electrode layer and at least one diaphragm layer, wherein the electrode layer and the diaphragm layer are arranged stacked on each other, and wherein the electrode layer and the diaphragm layer are cooperatively joined to each other at the interface facing each other by means of a molten and ion-conducting adhesive connection material. Here, the cell component is in particular a unit cell or a half cell of a solid cell. A particularly suitable cell component is achieved by the adhesive connection according to the present invention.

[0033] In an advantageous design, the cell component is in particular implemented as a single-chamber cell stack and has a plurality of electrode layers which are alternately implemented as cathodes and anodes, the electrode layers being arranged separated from one another with diaphragm layers respectively inserted in between, wherein the electrode layers and the diaphragm layers are respectively joined to one another by means of a molten ion-conducting adhesive connecting material.

[0034] The solid-state cell according to the present invention has the cell components described above. Here, the embodiments related to the cell components are also suitable for the solid-state cell, and vice versa.

[0035] The solid-state battery according to the invention is provided and suitable for use and is designed for use in a motor vehicle. The solid-state battery is designed, for example, as a traction battery for an electrically driven or drivable motor vehicle, in particular an electric vehicle or a hybrid vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The embodiments of the present invention are explained in more detail below with reference to the accompanying drawings, wherein the following are schematically and simplified diagrams:

[0037] Figure 1 Anode-half-cell is shown,

[0038] Figure 2 An anode-interlayer cell is shown.

[0039] Figure 3 shows a cathode-half-cell,

[0040] Figure 4 A cathode-interlayer cell is shown,

[0041] Figure 5A single-chamber cell in the first embodiment is shown.

[0042] Figure 6 A single chamber cell in a second embodiment is shown, and

[0043] Figure 7 Different embodiments are shown for a single-chamber cell stack.

[0044] In all the figures, components and variables that correspond to one another are always provided with the same reference symbols. DETAILED DESCRIPTION

[0045] According to the following Figures 1 to 7 The cell design for a solid cell according to the invention is explained. According to the invention, a solid cell is assembled here from prefabricated or preassembled cell components 2, 4, 6, 8, 10, 11. Here, the cell components 2, 4, 6, 8, 10, 11 can be manufactured by means of the method according to the invention. The cell components 2, 4, 6, 8, 10, 11 are cell layer systems with a plurality of cell layers or cell stacks.

[0046] Here, Figure 1 A cell component 2 embodied as an anode half-cell is shown.

[0047] exist Figure 1 In the embodiment shown in the figure, the anode semi-cell 2 has an electrode layer 12, in particular an anode layer, and a diaphragm layer 14 joined to the electrode layer. The anode layer 12 has a thin-film current arrester 16, which is coated on both sides with an active material 18, in particular an anode material. Here, the boundary surface 20 facing the diaphragm layer 14 is materially joined and in contact with the diaphragm layer 14 via an adhesive connection that is not shown in detail. For this purpose, when producing the anode semi-cell 2, a molten and ion-conducting adhesive containing ethylene carbonate is applied to the boundary surface 20 and then bonded to the diaphragm layer 14.

[0048] exist Figure 2 In the embodiment of the present invention, the cell component 4 is implemented as an anode-sandwich cell. Here, the anode-sandwich cell 4 has two diaphragm layers 14, between which the anode layer 12 is arranged in a sandwich manner. Here, the anode layer 12 has two end-side or flat-side boundary surfaces 20 in the region of the active material coating 18, and the two boundary surfaces are bonded to the correspondingly associated diaphragm layer 14 by a melt adhesive.

[0049] exist Figure 32 shows a cell component 6 designed as a cathode semi-cell, which is designed corresponding to the anode semi-cell 2. In this case, the cathode semi-cell 6 has an electrode layer 22 designed as a cathode layer instead of the anode layer 12. The cathode layer 22 has a current arrester 26 coated on both sides with an active material or cathode material 24. The surface of the cathode layer 22 or the cathode material 24 facing the separator layer 14 is bonded and contacted to the separator layer 14 at its interface 20 by means of a molten and ion-conducting adhesive connection.

[0050] Figure 4 A cell component 8 embodied as a cathode sandwich cell is shown, which is designed correspondingly to the anode sandwich cell 4 .

[0051] The half cells 2 and 6 form the smallest structural assembly or building block when making a solid cell, wherein the sandwich cells 4 and 8 are the next larger building blocks.

[0052] The half cells 2, 6 can be assembled into a cell component 10, which is also referred to as a single-chamber cell below. Preferably, the half cells 2, 6 are assembled into a single-chamber cell 6 using an ion-conducting and molten adhesive. In other words, the electrode layer 12, 22 of one half cell 2, 6 is materially bonded and contacted with the diaphragm layer 14 of the other half cell 6, 2 at the interface 20. Here, Figure 5 An anode / diaphragm / cathode / diaphragm-single-chamber cell 6 is shown, and Figure 6 A membrane / anode / membrane / cathode-single-chamber cell 6 is shown.

[0053] Preferably, the cell stack of the solid-state cell or solid-state battery is formed by a cell component 11 in the form of a cell stack, in which the cell cells 10 are directly stacked alternately on each other. Here, the cell stack 11 has at least two cell cells 10. Here, the cell cells 10 are joined and contacted with each other at the respective facing interfaces 20 using an ion-conducting and molten adhesive.

[0054] Figure 7 Four different single-chamber cell stacks 11 are shown, which differ from one another in terms of their energy optimization Eopt. Figure 7 The left side of FIG. 1 shows a single-chamber single-cell stack 11 with the lowest energy optimization Eopt, where Figure 7 The single-chamber cell stack 11 with the highest energy optimization Eopt is shown on the right side of FIG. The single-chamber cell stack 11 is provided with reference numerals merely by way of example.

[0055] from Figure 7Starting from the left side, the first single-chamber cell stack 11 has three single-chamber cells 10 stacked on each other and materially bonded to each other. As the energy optimization Eopt increases, it can be said that the cell layers 12, 14, 22 are eliminated respectively. Here, the cathode layer 22 provides the ions required for ion transport during operation of the battery cell. Since each cathode layer 22 is coated on both sides, the bottom or end cathode layer 22 that is not sandwiched between the two anode layers 12 cannot be effectively used, so that this cathode layer can be eliminated to improve the energy optimization Eopt. Preferably, the single-chamber cell stack 11 therefore has an anode layer 12 on the end side respectively. Thereby, the number of ions is reduced, and thus the risk of electroplating is also reduced.

[0056] The claimed invention is not limited to the embodiments described above. Rather, other variants of the invention may also be derived by a person skilled in the art within the scope of the disclosed claims without departing from the subject matter of the claimed invention. In particular, all individual features described in conjunction with the different embodiments may also be combined in other ways within the scope of the disclosed claims without departing from the subject matter of the claimed invention.

[0057] For example, cell components consisting of a combination of half cells 2 , 6 and sandwich cells 4 , 8 are also conceivable, which can be used as structural units for direct stacking to form a single-chamber cell stack 11 .

[0058] Reference numerals list

[0059] 2-cell component, anode - half-cell

[0060] 4-cell component, anode-sandwich cell

[0061] 6-cell component, cathode - half-cell

[0062] 8-cell component, cathode-sandwich cell

[0063] 10 single-cell components, single-chamber single-cell

[0064] 11 single-cell components, single-chamber single-cell stacking

[0065] 12Electrode layer, anode layer

[0066] 14 Diaphragm layer

[0067] 16 Current discharger

[0068] 18 Active materials, anode materials

[0069] 20 interface

[0070] 22Electrode layer, cathode layer

[0071] 24 Active materials, cathode materials

[0072] 26 Current Arrester

[0073] Eopt Energy Optimization

Claims

1. A method for producing a solid-state cell, - wherein at least one electrode layer (12, 22) and at least one separator layer (14) are provided, -in, Applying a molten and ion-conducting adhesive to the interface (20) of the separator layer (14) and / or the electrode layer (12, 22), wherein the electrode layers (12, 22) and the separator layer (14) are arranged one on top of the other, and wherein the interface (20) between the separator layer (14) and the electrode layers (12, 22) are bonded to one another in a cohesive manner while forming an ion-conducting adhesive bond.

2. The method according to claim 1, It is characterized in that An adhesive having ethylene carbonate was used.

3. The method according to claim 1 or 2, It is characterized in that Ethylene carbonate was used as a binder.

4. A cell component (2, 4, 6, 8, 10, 11) for a solid-state cell, comprising at least one electrode layer (12, 22) and at least one separator layer (14), wherein: The electrode layers (12, 22) and the separator layers (14) are arranged one on top of the other and are bonded to one another at interfaces (20) facing one another by means of a molten and ion-conducting adhesive connection material.

5. The single cell component (10, 11) according to claim 4, comprising a plurality of electrode layers (12, 22) alternately embodied as cathodes and anodes, the electrode layers being arranged spaced apart from one another with a separator layer (14) interposed therebetween, wherein: The electrode layers (12, 22) and the separator layer (14) are each joined to one another in a sealing manner by means of a fusible and ion-conducting adhesive bonding material.

6. A solid cell having a cell component (2, 4, 6, 8, 10, 11) according to claim 4 or 5.

7. A solid battery for a motor vehicle, comprising the solid-state cell according to claim 6.

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