SOLID CELL BATTERY AND METHOD FOR PRODUCING SUCH A SOLID CELL BATTERY

Description

[0001] The invention relates to a solid-state battery and a method for manufacturing such a solid-state battery according to the preamble of the independent claims.

[0002] Solid-state batteries (all-solid-state batteries) are manufactured using solid, ionically conductive separators, mostly made of ceramic materials that cannot be continuously processed or reshaped. Therefore, unlike conventional lithium-ion batteries, the separator cannot be folded in a Z-shape around the anode and cathode with a liquid electrolyte to create a cell stack in such a battery. This limitation can be explained by the characteristic material properties of the separator material and its thickness.

[0003] Single-sheet stackers are preferably used to manufacture cell stacks, building the battery stack layer by layer. The battery stack is assembled from individual electrodes and separators, growing in height incrementally. A significant disadvantage of this method is the comparatively long processing time for assembling a cell stack from individual elements due to the numerous stacking operations. Another disadvantage of manufacturing a solid-state battery using a single-sheet stacker is that a conventional single-sheet stacker is unable to deposit a collector bonded with adhesive. Therefore, an additional robot would be required to apply adhesive during and after collector placement for certain cell types. This is particularly challenging due to the adhesive's electrical conductivity and its aerosolized application.

[0004] By employing Z-folding, productivity can be increased by approximately 25%, just as with a conventional lithium-ion cell, simply by reducing the number of layers when stacking the cell stack. Furthermore, a Z-folding process would allow the use of a collector that is already coated with adhesive, thus avoiding a multitude of problems. Additionally, the cell stack would exhibit greater mechanical stability, significantly simplifying the handling of the otherwise comparatively fragile cell stack.

[0005] Currently, no z-folded solid electrodes are known for use in solid-state cells. Furthermore, a process for the corresponding folding of an electrode or separator is currently unknown due to the described material properties of the ceramic separator material.

[0006] From DE 10 2015 201 281 A1, a method for manufacturing a solid-state battery, in particular a lithium-ion solid-state cell, is known, comprising a first conductor layer and a second conductor layer and at least one separating layer, which are stacked to form a layer stack consisting of at least two first conductor layers and at least two second conductor layers. The first conductor layer is separated from the second conductor layer by the separating layer. The layers of the first conductor layer and / or the layers of the second conductor layer separated by the separating layer are electrically connected layer by layer. At least one of the conductor layers is formed from a flexible web, wherein the flexible web is inserted into the layer stack as a continuous layer that jointly forms at least the two first conductor layers and / or the two second conductor layers.Furthermore, a solid-state battery manufactured according to such a method is known from DE 10 2015 201 281 A1.

[0007] WO 2017 / 158 319 A1 discloses a method for manufacturing an energy storage device in which a stack is formed comprising at least a first electrode layer, a first current collector layer, and an electrolyte layer arranged between the first electrode layer and the first current collector layer. For this purpose, a first groove is formed in the stack through the first electrode layer and the electrolyte layer, thereby creating exposed edges of the first electrode layer and the electrolyte layer. Subsequently, at least a portion of the first groove is filled with an electrically insulating material, thereby covering the exposed edges of the first electrode layer and the electrolyte layer with the insulating material. The insulating material and the first current collector layer are cut along at least a portion of the first groove to form an exposed edge of the first current collector layer.

[0008] From DE 10 2016 219 661 A1, a method for manufacturing a galvanic lithium-ion cell is known. In this method, a separator is provided for the spatial separation of a first electrode material of the lithium-ion cell from a second electrode material. The first electrode material is applied to a first side of the separator by coating. Furthermore, a galvanic lithium-ion cell manufactured according to this method is known from DE 10 2016 219 661 A1.

[0009] US 2021 / 0020921 A1 describes a battery cell with at least one electrode plate. The electrode plate contains a composite current collector with an ionically conductive material and two active material layers arranged on the composite current collector. The active material layers comprise a positive active material layer and a negative active material layer. The composite current collector is positioned between the positive active material layer and the negative active material layer. Each positive and negative active material layer is bonded to the ionically conductive material. The battery cell is a multilayer structure assembled by folding a single electrode plate onto itself or by stacking the electrode plates, with adjacent active material layers in two adjacent layers of the battery cell having the same polarity.

[0010] EP 3 910 701 A1 describes a solid-state battery and a method for its manufacture. In one example of an embodiment of the solid-state battery and the method for its manufacture, a positive current collector is folded to electrically connect positive layers, while a negative current collector is folded to electrically connect negative layers.

[0011] German patent DE 10 2010 055 617 A1 discloses a method and a system for manufacturing an electrode stack consisting of a cathode, anode, and separator for a battery. One of the components is in the form of continuous material. At least one other component is separated and then attached to the component in the continuous material. The electrode stack is then completed.

[0012] Furthermore, DE 10 2012 019 975 B3 discloses a stacking device for stacking disc-shaped electrodes with a separator film inserted in a zigzag pattern between them by a guide device. The stacking device comprises a stacking table, hold-down devices for fixing the stack, grippers for picking up and precisely placing the electrodes, which are equipped with an overpressure module for selectively forming a defined film pocket in the separator film.

[0013] The invention is based on the objective of simplifying the manufacturing of a solid-state battery and overcoming the disadvantages known from the prior art.

[0014] This problem is solved by a process for manufacturing a solid-state battery with a carrier film, a separator, a cathode, and a continuous collector film. The process comprises the following steps: Placing the carrier film on a storage table, feeding a first layer of the continuous collector film by means of a winding device, feeding the separator, the cathode and another separator in a stacking process, whereby a cell stack is formed, feeding a second layer of the continuous collector film, wherein the continuous collector film is fed by means of a winding device, wherein the continuous collector film is positioned relative to the cell stack by a horizontal displacement of the storage table and / or by a horizontal displacement of at least one guide roller of the winding device, thereby achieving a folding of the collector film.

[0015] It is particularly advantageous if the solid-state battery does not have a fixed anode formed by stacking a lithium anode on top of the cell stack, but rather an anode that forms in situ on the separator surface facing away from the cathode. Alternatively, the separator can also be metallically coated on the side facing the collector foil. This eliminates the need for an additional stacking step during cell stack production, significantly accelerating the manufacturing of the solid-state battery.

[0016] The proposed method enables significantly faster and simpler production of solid-state batteries. In particular, the manufacturing process can be shortened because the collector film is not applied to the cell stack via an additional stacking process, but rather fed as a continuous material, specifically as a strip or film, from a dispensing unit. Specifically, in this method, only the collector film, and not the separator, is folded, thereby reducing the number of stacking operations during cell stack production by 25%. If a functional unit consisting of a separator and cathode, a so-called monocell, is added during cell stacking instead of the separator and cathode, the number of stacking operations can be reduced even further.If the functional unit includes a separator, a cathode and another separator, and is designed as a so-called bi-cell, the number of stacking operations can be reduced even further and the cycle time in the production of the solid-state battery can be shortened even further.

[0017] The additional features listed in the dependent claims enable advantageous improvements and further developments of the method for manufacturing a solid-state battery specified in the independent claim.

[0018] In a preferred embodiment of the invention, the collector film is provided with an adhesive layer on at least one side and is bonded to the cell stack when the collector film is positioned relative to a free surface of the cell stack. Applying an adhesive layer to the collector film further improves and accelerates the manufacturing process. It also eliminates the need for additional bonding steps, thus increasing process reliability. Furthermore, the mechanical strength of the cell stack is increased because the components of the cell stack are fixed to the collector film by the adhesive layer. This facilitates, in particular, the handling of the cell stack and the stacking of further cell stack elements, especially additional separators and cathodes.

[0019] It is particularly preferred if the adhesive layer is applied to the collector film as a UV-activated adhesive and activated by means of a UV radiation source, in particular a UV lamp, when the collector film is positioned relative to the cell stack. A UV-activated adhesive enables particularly easy feeding of the collector film, since there is no risk of the collector film sticking to the guide rollers of the unwinding device during feeding.

[0020] In a further preferred embodiment of the invention, the adhesive layer is applied to the collector film as a pressure-sensitive adhesive. A pressure-sensitive adhesive layer also makes it possible, in a simple and cost-effective manner, to feed a collector film already provided with an adhesive layer to the cell stack of the solid-state battery and to bond this cell stack to the collector film.

[0021] Alternatively, it is advantageously provided that the adhesive layer is applied to the collector film as a reactive adhesive, wherein the reactive adhesive is activated upon contact with the cell stack or with an activator, in particular with air.

[0022] It is particularly preferred if the collector film is coated with a protective layer, especially a protective film, and this protective layer is removed when the collector film is fed to the cell stack. In this way, the adhesive layer or the reactive adhesive can be covered by the protective layer until the collector film is fed directly to the cell stack by a final guide roller of the unwinding device. This minimizes the risk of the unwinding device becoming stuck or the risk of premature activation of the reactive adhesive.

[0023] In an alternative embodiment of the method, it is provided that an adhesive is applied to the cell stack, in particular sprayed on, and the collector film is bonded to the cell stack.

[0024] In an advantageous embodiment of the method, the solid-state battery is provided to have several compartments, with the feed direction of the collector film being alternately changed between the different compartments. This allows a meandering fold of the collector film to be achieved in a simple manner.

[0025] In a further advantageous embodiment of the method, the height of the cell stack is monitored and the collector film is separated when the cell stack reaches a defined target height or a defined number of compartments. This allows the collector film to be separated and subsequently bonded to the cell stack.

[0026] In a further improvement to the process, the cell stack is wrapped with the carrier film once a defined number of compartments or a defined stack height has been reached. This allows for simple isolation of the cell stack.

[0027] A system suitable for manufacturing such a solid-state battery comprises at least one stacking table, at least one robot for assembling a cell stack, a winding device for feeding the collector film to the cell stack, a cutting device for separating the collector film, and a control unit. The control unit has a storage unit and a processing unit, the storage unit containing machine-readable program code. The control unit executes a method described in the preceding sections when the machine-readable program code stored in the storage unit is executed by the processing unit of the control unit. Such a system enables the rapid and cost-effective production of solid-state batteries.

[0028] Another aspect of the invention relates to a solid-state battery comprising a carrier film, a first separator, a cathode, a second separator, and a continuous collector film, wherein the solid-state battery is manufactured according to a method described in the preceding sections. By reducing the number of stacking operations and shortening the time required for the stacking process, the manufacturing costs for such a solid-state battery can be reduced.

[0029] In an advantageous embodiment of the solid-state battery, the collector foil is a metallic foil, in particular a copper foil, an aluminum foil, or a plastic foil with a coating of an electrically conductive material. To ensure that the collector foil is both electrically conductive and possesses sufficiently high mechanical strength, the use of a metallic foil is advantageous. With regard to electrical conductivity and its suitability as a continuous material, a copper foil is particularly preferred as a collector foil. Alternatively, an aluminum collector foil or an aluminum-coated collector foil can be used. This is only feasible in solid-state cells, as there is no liquid electrolyte present that could dissolve the aluminum on the anode side.

[0030] The collector film can also have an additional coating with at least one additional layer. This layer can, for example, comprise an electrically conductive metal or a separator.

[0031] The collector film can also consist of a thermoplastic or thermosetting plastic, which is coated on both sides with an electrically conductive material, in particular copper, aluminum or carbon.

[0032] A further improvement to the solid-state battery involves incorporating a discharge contour on the collector film. This discharge contour reduces the weight of the collector film. Furthermore, it simplifies the electrical contacting of the compartments, as the spaces between the discharge contours facilitate electrical contact. Additionally, a targeted geometric design of the discharge contour can optimize the temperature distribution within the solid-state battery and adapt the contact resistance to the cathode-side contact.

[0033] According to an advantageous embodiment of the solid-state battery, the collector film is provided with an adhesive layer of an electrically conductive adhesive on at least one side. Preferably, the collector film is provided with an electrically conductive adhesive on both sides. Alternatively or additionally, an electrically conductive adhesive is applied to the collector film or to a component to be joined to the collector film. To enable easy electron flow at the adhesive joint, it is advantageous that at least one side of the collector film, and preferably both sides of the collector film, are provided with an electrically conductive adhesive. This can be achieved, in particular, by coating or spraying an adhesive.

[0034] In a preferred embodiment of the solid-state battery, the battery comprises several compartments, with the collector film arranged in a meandering or S-shaped pattern between the individual compartments. This allows a continuous material, in particular a film or strip material, to be easily connected to the solid components, especially the separators and cathodes of the cell stack.

[0035] The various embodiments of the invention mentioned in this application can be advantageously combined with one another, unless otherwise specified in individual cases.

[0036] The invention is explained below using exemplary embodiments with reference to the accompanying drawings. These show: Figure 1 shows an embodiment of a solid-state battery according to the invention; Figure 2 shows a plant set up for carrying out the method according to the invention for producing a solid-state battery according to the invention; Figure 3 shows a method according to the invention for producing such a solid-state battery; and Figure 4 shows a flowchart for carrying out a method according to the invention for producing a solid-state battery.

[0037] Figure 1Figure 1 shows a schematic representation of a cell stack 19 of a solid-state battery 10 according to the invention. Due to the structure of certain solid-state batteries 10, it is possible to fold a collector film 14 in a meandering or S-shaped manner around a cell stack 19 consisting of a separator 16 and a cathode 20. Preferably, a metallic collector film 14, in particular a copper foil 28, an aluminum foil, or a plastic film coated with an electrically conductive metal, is used, which is wetted or coated with an electrically conductive adhesive, in particular an electrically conductive adhesive layer 24. The meandering fold eliminates the need for an additional "pick-and-place" process, thereby reducing the manufacturing time of the solid-state battery 10. A conductive contour 22 can be formed on the collector film 14.The adhesive layer 24 can, in particular, comprise a UV-activated adhesive 26, a pressure-sensitive adhesive 36, or a reactive adhesive 38. Figure 1 A mono-cell with only one compartment 34 is shown, but the proposed method is particularly suitable for solid-state cell batteries 10 with multiple compartments 34, 35, 37. The adhesive layer 24 can be designed as a one- or multi-component adhesive layer 24. If a protective layer 52, in particular a protective film 54, is applied to the collector film 14, the protective layer 52 is removed immediately before the collector film 14 is connected to the cell stack 19.

[0038] In Figure 2Figure 100 shows a system for manufacturing such a solid-state battery 10. The system 100 comprises at least one storage table 30, at least one robot 50, in particular a pick-and-place system for assembling a cell stack 19, a unwinding device 40 for feeding the collector film 14 to the cell stack 19, a cutting device 48 for cutting the collector film 14, and a control unit 60 for controlling the manufacturing process. The control unit 60 comprises a storage unit 62, in which a machine-readable program code 66 is stored, and a processing unit 64 for executing the program code. To manufacture the solid-state battery 10, a carrier film 12, in particular a plastic substrate, is first laid on a Figure 2 The collector film 14 is placed on the illustrated support table 30 and fixed in place. The collector film 14 is then rolled and / or glued onto this carrier film 12. The unrolling of the collector film 14 can be carried out as shown in Figure 2This is achieved by moving one or more guide rollers 42, 44, 46 of a unwinding device 40 or by moving the discharge table 30. Preferably, as shown in Figure 2The figure shows a winding device 40 with a first guide roller 42, a second guide roller 44, and a third guide roller 46. The collector film 14 is tensioned by the guide rollers 42, 44, and 46. The third guide roller 46 serves to position the collector film 14 relative to the cell stack 19. In addition to tensioning the collector film 14, the first guide roller 42 and the second guide roller 44 can also have additional functions, in particular applying an adhesive layer or removing a protective film 54 applied to the collector film 14. A sliding device 32 is provided on the storage table 30 for moving it horizontally. In a subsequent process step, one or more robots 50 place a separator 16, a cathode 20 and another separator 16 into a defined cell stack 19 on the collector film 14.After the battery elements are placed, the guide rollers 42, 44, 46 move the collector film 14, coated with adhesive 24, over the cell stack 19, folding the collector film 14 in a meandering pattern. This procedure is repeated until a defined number of compartments 34, 35, 37 are reached. Finally, the collector film 14 is cut off by a separating device 48 and is ready for the assembly of the next cell stack 19. Preferably, a robot 50 is positioned on each side of the cell stack 19 to accelerate the assembly process and increase component availability. To accelerate the assembly of the cell stack 19, prefabricated components having a separator-cathode assembly or a separator-cathode-separator assembly can be used. The anode (metallic lithium) of the solid-state battery 10 can form in situ on the side of the separator 16 facing away from the cathode 20.The anode can thus be part of the separator 16 and can be built up during each charging process and removed again during each discharging process of the solid-state battery 10. Alternatively, the anode can also be part of the collector foil 14 or form on a surface of the collector foil facing the separator 16. In principle, the metallic lithium of the anode in the solid-state battery 10 according to the invention is built up by electrochemical processes.

[0039] The robot 50 can have a spray device 56 with which an adhesive 58 is applied to the cell stack 19 in order to bond the cell stack 19 to the collector film 14.

[0040] In Figure 3 The process for manufacturing a solid-state battery 10 according to the invention is shown. As already mentioned in the previous section... Figure 2In the first manufacturing step, a carrier film 12 is placed on the storage table 30 and fixed in place. The collector film 14 is then rolled and / or glued onto this carrier film 12, and the corresponding separators 16 and cathodes 20 are stacked onto the collector film 14. A second layer of the collector film 14 is then applied to the cell stack 19, with the feed direction being opposite to that of the first layer of collector film 14. The feed is controlled by the guide rollers 42, 44, 46 of the unwinding device 40.

[0041] In a further process step 2, the inflexible components 16, 18, 20 are again stacked on the cell stack 19. Furthermore, in a process step 3, the storage table 30 is moved downwards and / or the lowest guide roller 46 of the unwinding device 40 is moved upwards to create additional space for another compartment 35, 37 of the cell stack 19 of the solid-state battery 10.

[0042] In process step 4, the lowest guide roller 46 of the unwinding device 40 and / or the depositing table is moved in a horizontal direction to place another layer of the collector film 14 on the cell stack 19 and to fold the collector film 19 in a meandering pattern as described.

[0043] In process step 5, further stacking operations are performed on separator 16, anode 18, cathode 20, and other inflexible battery components. In a final process step 6, the collector film 14 is separated when a defined number of compartments 34, 35, 37 have been reached or the cell stack 19 has reached a defined height. The free end of the collector film 14 is then bonded to the surface of separator 18, which lies on top of the cell stack 19.

[0044] Figure 4shows a flowchart for the production of such a solid-state battery 10. In one process step <100> First, a carrier film 12, in particular a plastic substrate, is placed on the storage table 30 and fixed there. In one process step <110> The collector foil 14 is fed in as a strip material and then bonded to the carrier foil 12 in a process step <120<. In a further process step <130> One or more robots 50 stack a separator 16, a cathode, and another separator 16 onto the collector film 14, creating a cell stack 19. In one process step <140> The storage table 30 and / or at least one guide roller 42, 44, 46 of the unwinding device 40 is moved to feed the collector film 14 to the cell stack 19 again. This feeding takes place from the opposite direction to the first feeding, so that the collector film 14 is folded in a meandering shape.In one process step <150> The height of the cell stack 19 or the number of compartments 34, 35, 37 of the cell stack 19 is determined. Once the cell stack 19 has reached its target height and / or the desired number of compartments 34, 35, 37, the collector film 14 is removed in a process step. <160> separated from the tape material and finally bonded to the surface of the last free separator 16. Reference symbol list

[0045] 10 Solid-state battery 12 Carrier film 14 Collector film 16 Separator 19 Cell stack 20 Cathode 22 Conductor contour 24 Adhesive layer 26 UV-activated adhesive 28 Copper foil 30 Storage table 32 Sliding device 34 First compartment 35 Second compartment 36 Pressure-sensitive adhesive 37 Third compartment 38 Reactive adhesive 40 Unrolling device 42 First guide roller 44 Second guide roller 46 Third guide roller 48 Separating device 50 Robot 52 Protective layer 54 Protective film 56 Spray device 58 Adhesive 60 Control unit 62 Storage unit 64 Computing unit 66 Machine-readable program code

Claims

1. Method for producing a solid-state battery (10), comprising a carrier film (12), a separator (16), a cathode (20) and a continuous collector film or foil (14), wherein the method comprises the following steps: - placing the carrier film (12) on a work table (30), - supplying a first layer of the continuous collector film or foil (14) by means of an unrolling device (40), - supplying the separator (16), the cathode (20) and a further separator (16) in a stacking process, with a cell stack (19) being formed, - supplying a second layer of the continuous collector film or foil (14), with the collector film or foil (14) being supplied by means of an unrolling device (40), wherein - the continuous collector film or foil (14) is positioned relative to the cell stack (19) by horizontal displacement of the work table (30) and / or by horizontal displacement of at least one guide roller (42, 44, 46) of the unrolling device (40), as a result of which the collector film or foil (14) is folded.

2. Method for producing a solid-state battery (10) according to Claim 1, wherein the collector film or foil (14) is provided with an adhesive layer (24) at least on one side of the collector film or foil (14) and the collector film or foil (14) is adhesively bonded to the cell stack (19) when the collector film or foil (14) is positioned relative to a free surface of the cell stack (19).

3. Method for producing a solid-state battery (10) according to Claim 2, wherein the adhesive layer (24) is applied to the collector film or foil (14) as a UV-activatable adhesive and is activated by means of a UV radiation source when the collector film or foil (14) is positioned relative to the cell stack (19).

4. Method for producing a solid-state battery (10) according to Claim 2, wherein the adhesive layer (24) is applied to the collector film or foil (14) as a pressure-sensitive adhesive (36).

5. Method for producing a solid-state battery (10) according to Claim 2, wherein the adhesive layer (24) is applied to the collector film or foil (14) as a reactive adhesive (38), wherein the reactive adhesive (38) is activated on contact with the cell stack (19).

6. Method for producing a solid-state battery (10) according to any of Claims 3 to 5, wherein the collector film or foil (14) is coated with at least one protective layer (52), in particular at least one protective film, and this protective layer (52) is removed when the collector film or foil (14) is supplied to the cell stack (19).

7. Method for producing a solid-state battery (10) according to Claim 1, wherein an adhesive (58) is sprayed onto the cell stack (19) and the collector film or foil (14) is adhesively bonded to the cell stack (19).

8. Method for producing a solid-state battery (10) according to any of Claims 1 to 7, wherein the solid-state battery (10) has a plurality of compartments (34, 35, 37), wherein the supply direction of the collector film or foil (14) is changed in an alternating manner between the different compartments (34, 35, 37).

9. Method for producing a solid-state battery (10) according to any of Claims 1 to 8, wherein a height of the cell stack (19) is monitored and the collector film or foil (14) is separated when the cell stack (19) has reached a defined target height.

10. Method for producing a solid-state battery (10) according to any of Claims 1 to 9, wherein the carrier film (12) is wound around the cell stack (19) after a defined number of compartments (34, 35, 37) or a defined stack height of the cell stack (19) has been reached.

11. Solid-state battery (10), comprising a carrier film (12), a first separator (16), a cathode (20), a second separator (16) and a continuous collector film or foil (14), wherein the solid-state battery (10) is produced using a method according to any of Claims 1 to 10.

12. Solid-state battery (10) according to Claim 11, wherein the collector film or foil (14) is a metallic foil, in particular a copper foil (28), an aluminium foil or a plastic film coated with an electrically conductive metal.

13. Solid-state battery (10) according to Claim 11 or 12, wherein a discharge contour (22) is formed on the collector film or foil (14).

14. Solid-state battery (10) according to any of Claims 11 to 13, wherein the solid-state battery (10) comprises a plurality of compartments (34, 35, 37), wherein the collector film or foil (14) is arranged between the individual compartments (34, 35, 37) in a meandering or S-shaped manner.