Method for manufacturing an energy storage device

Abstract

Method for manufacturing an energy storage device (100), comprising the following steps: Arranging a pressure screen (200) over a pressure pad (210) which is designed to support a cell element (102) or cell stack (104) of the energy storage device (100); Applying a paste (121; 122) having a rest viscosity of at least 200 Pa s to the printing screen (200); and Brushing the paste (121; 122) through sieve openings (202) of the printing sieve (200) to form an electrode layer (101) of the cell element (102) or cell stack (104) on the printing surface (210), wherein the electrode layer (101) is formed with a raised area (301) of at most 5 µm and / or with an edge angle (300) of at most 5°.

Description

Technical area

[0001] The invention relates to a manufacturing method for an energy storage device, in particular a method for manufacturing an energy storage device containing an electrochemical cell. Technical background

[0002] An electrochemical cell comprises a cathode (a positive electrode), an anode (a negative electrode), and a separator that separates the positive electrode from the negative electrode. In a conventional battery cell, the positive electrode, the negative electrode, the separator, and a liquid electrolyte, in which the aforementioned positive electrode, the negative electrode, and the separator are at least partially contained, are housed in a housing. In a solid-state battery cell, the separator is formed with a solid electrolyte. The anode and cathode can form an electrical circuit with a consumer via contacts. An electrochemical cell can be used for energy storage in the form of a primary battery or a secondary battery. A primary battery is a non-rechargeable battery intended for single use.A secondary battery or accumulator is a battery that is rechargeable.

[0003] US 2020 / 0083518 A1 discloses a battery with a lithium metal anode made of a printable lithium composition. To test the printability of a lithium composition, it is filtered through a stainless steel mesh with an opening of 180 µm and filled into a syringe, which is loaded into a syringe dispenser and attached to a slot-nozzle printhead. A zero-shear viscosity of a printable lithium composition in the range of 10 to 10 4 Pa s keeps the lithium in suspension, especially during storage.

[0004] In a known roll-to-roll wet coating process for producing battery cells, a low-viscosity slurry containing a respective electrode material for the anode and cathode is applied sequentially to both sides of a metallic conductor, and the solvent is then evaporated. For cell assembly, the resulting electrode rolls are then cut and stacked together with a separator, alternating between anode, separator, and cathode, until the desired capacity is achieved. The stack is then electrically connected and packaged in a housing, e.g., a foil bag. A liquid electrolyte is then added, and the housing is sealed. The resulting cell has a nominal voltage of approximately 3.2 V, depending on the cathode material.A disadvantage of this manufacturing process is the multitude of different production steps that must be carried out using various specialized production devices. This not only requires a complex production facility, but also requires time-consuming movement of intermediate products from one production device to another during the production process.

[0005] US 5,035,965 A discloses a manufacturing method for a flexible thin-film cell in which an electrolyte material and a positive polarity material are applied to a lithium-aluminum foil as the negative polarity material, and then a positive polarity material are applied to the electrolyte material by screen printing and then dried in a UV calcination oven. The viscosity of the polymer used in the screen printing device is set to approximately 30 Pa s. Under the same conditions, a conductor is applied in a further screen printing and drying process. The thin-film cell units are then laminated between housing materials with lead terminals, fusion-bonded under vacuum, and cut into predetermined sizes.A multilayer structure can be fabricated by fusion bonding lithium aluminum foil to the positive polarity material before applying the arrester and repeating the application and drying of the electrolyte material and the positive polarity material.

[0006] US 2005 / 0 239 917 A1 discloses screen printing of battery anodes with lithium metal powder-based inks having a viscosity of 0.5 to 50 Pa s at 25°C. US 2013 / 0 192 997 A1 discloses screen printing of electrodes and / or electrolyte of high-temperature electrochemical cells with an aqueous ink containing particles of at least one mineral filler, at least one binder, and at least one dispersant. Preferably, the viscosity of the aqueous ink is between 1 and 60 Pa s at compressive shear. US 2016 / 0 126 554 A1 discloses screen printing of electrodes of a lithium-ion battery with an ink whose viscosity at a shear rate of 1 s -1 preferably in the range of 0.1 to 50 Pa s. US 2017 / 0288232 A1 discloses the screen printing of an approximately 100 µm thick graphite battery electrode with a water-based paste which is -1and 25 °C has a viscosity of 34.4 Pa s. US 2003 / 0 165 744 A1 discloses, in order to produce a sound card circuit with a printed battery, screen printing a circuit using silver ink dissolved in acetic acid diethylene glycol monobutyl ether ester onto a thick polyester film.

[0007] FR 2 690 567 A1 proposes a manufacturing method for an electrochemical generator with a thin thickness of between 10 µm and 100 µm. A cathode current collector, a cathode, an electrolyte separator, an anode, an anode current collector, and an encapsulation material are applied successively and one above the other to a glass-epoxy composite substrate, each layered by means of partially multilayer screen printing processes, followed by three hours of drying at 100 °C under primary vacuum after each layer. The electrolyte separator, the anode current collector, and the encapsulation material are arranged at an angle to the sides of the cathode and anode, extending down to the glass-epoxy composite substrate, leaving outer sections of the current collectors uncovered by the encapsulation material.

[0008] Although this process involves a sequence of similar process steps, as with the manufacturing processes disclosed in US 5 035 965 A, US 2005 / 0 239 917 A1, US 2013 / 0 192 997 A1, and US 2016 / 0 126 554 A1, there is the problem that the screen printing processes only produce thin layers, which limits the storage capacity achievable per area of ​​the energy storage device. Furthermore, long drying times after the

[0009] Screen printing of the individual layers means that a considerable amount of time must be spent producing an energy storage device, which increases further when, for example, an electrode is formed from several individual layers.

[0010] It is therefore an object of the invention to increase the capacity of the energy storage device that can be achieved for a given lateral extension while keeping the manufacturing process costs, in particular in terms of time, to a minimum. Disclosure of the invention

[0011] The object is achieved by a method for producing an energy storage device according to patent claim 1. The method comprises a step of arranging a printing screen over a printing support which is designed to support a cell element or cell stack of the energy storage device, a step of applying a paste which has a rest viscosity of at least 200 Pa s to the printing screen and a step of spreading the paste through screen openings of the printing screen in order to form an electrode layer of the cell element or cell stack on the printing support, wherein the electrode layer is formed with an elevation of at most 5 µm and / or with an edge angle of at most 5°.

[0012] Throughout this description and the claims, the terms "above," "support," and "on" refer to a screen printing direction that preferably, but not necessarily, coincides with the direction of gravity during the screen printing steps. Terms commonly used to refer to the direction of gravity, such as "above," "below," "top," "height," or "next to," always refer to the printing direction. Accordingly, the term "housing side wall" refers to a housing wall that has a sideways-facing surface normal and thus extends parallel to the printing direction. "Printing support" refers to support that runs counter to the printing direction, e.g., in the form of a flat tabletop.Unless expressly stated otherwise, in this description and the claims, screen printing on an element does not necessarily mean that the screen-printed material is applied directly to said element, but may also mean that one or more further elements are arranged between said element and the screen-printed material, which are supported by said element counter to the printing direction. For example, forming the electrode layer on the printing support may also mean that the electrode layer is screen-printed on a metallic conductor layer, beneath which is a housing base that rests on the printing support and is supported by it counter to the printing direction.

[0013] The term "electrode layer" refers to both a layer that forms an electrode of the energy storage device on its own and one of several electrode sublayers that, when stacked on top of one another, together form the electrode. The process uses a screen printing process to form the electrode layer, so that a device is used that can also be used to form other elements of the energy storage device, such as conductor or separator layers. This keeps the process complexity to a minimum. Since screen printing is carried out with a paste that has a high resting viscosity of at least 200 Pa s, the screen-printed electrode layer retains its generated geometric shape even at greater thicknesses without flowing. This enables the formation of the electrode layer with a particularly thick layer, thus producing an energy storage device with a high storage capacity per unit area.In addition, the high resting viscosity of at least 200 Pa s allows the paste to be prepared with a particularly low solvent content, reducing the drying time required after screen printing the electrode layer to just a few minutes. This already shortens the time required to produce the energy storage device. Furthermore, it makes it possible to construct the electrode from several sublayers without great expenditure of time, for example, to achieve a greater electrode thickness with the associated increase in capacity or to achieve desired special properties of the electrode.

[0014] Superelevation refers to the height difference between the greatest height of the electrode layer near the edge and the smaller height of the electrode layer farther from the edge. A small superelevation allows for precise adjustment of the dimensions of the electrode layer. The edge angle refers to the angle formed by a lateral edge surface of the electrode layer relative to the vertical, i.e., the printing direction. A small edge angle allows for precise adjustment of the dimensions of the electrode layer.

[0015] According to a preferred embodiment, the viscosity during coating is at most 50 Pa s. By adjusting the paste with a particularly low shear viscosity in this way, it can be processed particularly precisely and thus enables a desired shape and desired dimensions of the electrode layer to be precisely realized.

[0016] According to a preferred embodiment, the paste comprises a binder with an epoxy resin and a solvent. In this way, in addition to desired viscosity values ​​of the paste, a desired porosity of the resulting electrode layer can be adjusted, which imparts advantageous storage properties to the energy storage device. This eliminates the need for a calendering step for subsequent mechanical modification of the porosity, which advantageously shortens the manufacturing process. The solvent preferably comprises diethylene glycol monobutyl ether acetate.

[0017] According to a preferred embodiment, the electrode layer is formed with a thickness of at least 100 µm, in particular at least 150 µm. This allows for the production of an energy storage device with high storage capacity with minimal manufacturing effort.

[0018] According to a preferred embodiment, the electrode layer is formed with a maximum elevation of 5 µm. Preferably, the maximum elevation is 1 µm.

[0019] According to a preferred embodiment, the electrode layer is formed with an edge angle of at most 5°. Preferably, the edge angle is at most 1°.

[0020] According to a preferred development, the method further comprises a step of drying the electrode layer for a drying time of no more than 10 minutes. This means a particularly short time expenditure for the production of the energy storage device. The drying time is preferably no more than 6 minutes.

[0021] According to a preferred development, the application and coating steps are repeated to form a first electrode sublayer and a second electrode sublayer of the electrode layer. In this way, a greater thickness of the electrode layer can be achieved, enabling a higher storage capacity of the energy storage device. Furthermore, by varying the composition of the paste between the electrode sublayers, it is possible to form a gradient within the electrode layer to influence the storage properties of the energy storage device.

[0022] According to a preferred embodiment, the steps of application and coating are repeated to form a separator layer of the cell element or cell stack, which separates the electrode layer from another electrode layer of the cell element or cell stack. The separator layer refers to both a solid electrolyte layer and an electrolyte-free porous layer for subsequent impregnation with liquid electrolyte. The steps of application and coating can also be repeated multiple times to apply the separator layer in multiple separator sublayers.

[0023] According to a preferred development, the method further comprises a step of arranging the cell element or cell stack in a housing, a step of filling the housing with a liquid electrolyte, and a step of closing the housing. This enables the advantageous integration of the method into existing manufacturing processes. Short description of the drawings

[0024] The method according to the invention is illustrated below using several embodiments. They show: Fig. 1 a schematic cross-sectional view of an energy storage device produced by a method according to an embodiment, Fig. 2 a schematic sectional front view of an apparatus for producing an energy storage device according to a method according to an embodiment, during the formation of a first electrode layer of the energy storage device, Fig. 2A is a partial enlargement of the electrode layer from Fig. 2, Fig. 3 the device from Fig. 2 when forming a second electrode layer of the energy storage device, Fig. 4 a flowchart of a method for producing an energy storage device according to an embodiment, Fig. 5A-S are schematic cross-sectional views of steps of a method for producing an energy storage device, according to an embodiment, and Fig. 6 a schematic cross-sectional view of an energy storage device manufactured by a method according to an embodiment. Detailed description of the drawings

[0025] In the drawings, unless expressly stated otherwise, identical or equivalent elements are provided with identical reference numerals.

[0026] Fig. 1 shows, in a schematic cross-sectional view, an energy storage device 100, which can be designed, for example, as a primary or secondary battery. The energy storage device 100 comprises a fluid-tight housing 106, e.g., in the form of a solid capsule or a foil bag, which is filled with a liquid electrolyte 107. An electrochemical cell element 102 is accommodated in the liquid electrolyte 107 within the housing 106. The cell element 102 is a flat, extended laminated body composed of several layers 110, 111, 112, 114, which has a first electrode layer 101 and a second electrode layer 114. Between the first electrode layer 101 and the second electrode layer 114 is a separator layer 110 made of a porous material, which is penetrated by the liquid electrolyte 107.

[0027] The first electrode layer 101 consists of a second electrode sublayer 112 adjacent to the separator layer 110 and a first electrode sublayer 111 adjacent to the side of the second electrode sublayer 112 facing away from the separator layer 110. The second electrode sublayer 112 is thinner than the first electrode sublayer 111. For example, the first electrode sublayer 111 has a thickness of 150 µm, while the second electrode sublayer 112 has a thickness of 50 µm. Both electrode sublayers 111, 112 have an active material suitable for acting as an electron donor or ion donor or as an electron receptor or ion receptor. In particular, during the discharge process of the energy storage device 100, electrons can be released through a chemical reaction in the active material.In particular, during a charging process of the energy storage device 100, electrons or ions can be bound in the active material by a chemical reaction. In particular, the chemical reactions can be electrochemical reactions. The chemical reactions can be reversible, depending on whether the energy storage device is discharged to provide electrical energy or the energy storage device is charged for the later provision of electrical energy. The second electrode sublayer 112 contains an admixture of the separator material, so that it is more porous than the first electrode sublayer 111, but less porous than the separator layer 110. This results in a decreasing concentration gradient of the liquid electrolyte 107 from the separator layer 110 via the second electrode sublayer 112 to the first electrode sublayer 111.

[0028] On the side of the first electrode sublayer 111 facing away from the second electrode sublayer 112, a first metallic conductor layer 115 is formed, which extends over the entire surface of the first electrode sublayer 111 and through the wall of the housing 106 into the exterior space. The second electrode layer 114 comprises a metallic material, e.g., an alkali metal such as lithium or sodium. On the side of the second electrode layer 114 facing away from the separator layer 110, a second metallic conductor layer 116 is formed, which covers part of the surface of the second electrode layer 114 and extends through the wall of the housing 106 into the exterior space. The ends of the metallic conductor layers 115, 116 accessible in the exterior space form electrical connections of the energy storage device 100 in order to draw electrical energy from the energy storage device 100 or, depending on the type, to supply it for charging.

[0029] Fig. 2 shows a screen printing device 212 for producing the first electrode layer 101 of an energy storage device 100 according to Fig. 1. The screen printing device 212 comprises a printing support 210, wherein the printing support 210 is designed to support a cell element 102 (see Fig. 1) or a cell stack 104 comprising several cell elements 102 (cf. Fig. 6) of the energy storage device 100. The screen printing device 212 comprises a printing screen 200, which has a plurality of screen openings 202. The screen printing device 212 further comprises a first application device 221 containing a first paste 121 and a second application device 222 containing a second paste 122, by means of which the pastes 121, 122 can be applied to the printing screen 200. A coating device 214 with a doctor blade 215 that can be coated over the printing screen 200 is designed to coat the pastes 121, 122 over the printing screen 200 and through the screen openings 202 in the direction of the print support 210.

[0030] The first paste 121 and the second paste 122 both contain an identical active material suitable for acting as an electron donor or ion donor, or as an electron receptor or ion receptor. The second paste 122 is further mixed with a proportion of, for example, 10% porous separator material. Both pastes contain a binder with an epoxy resin and diethylene glycol monobutyl ether acetate as a solvent. The composition of the first paste 121 is selected such that its resting viscosity is 250 Pa s and its shear viscosity is 50 Pa s. The solvent content of the second paste 122 is higher than the solvent content of the first paste 121 and is selected such that the second paste 122 has a resting viscosity of 100 Pa s.

[0031] The following will be based on the Fig. 4 flowchart with reference to Fig. 1 to 3 a method for producing an energy storage device 100 according to Fig. 1 using the screen printing device 212 Fig. 2. The method begins with step 400, in which a first metallic conductor layer 115, consisting of nickel, for example, is arranged on the printing support 210 of the screen printing device 212. This step can be performed either by means of a screen printing process or in another way, e.g., by providing a commercially available nickel foil.

[0032] In step 401, the first electrode sublayer 111 of the energy storage device 100 is formed by screen printing with the first paste 121 on the first metallic conductor layer 115. For this purpose, a suitable amount of the first paste 121 is applied to the printing screen 200 by means of the first application device 221. Subsequently, as in Fig. 2, the applied first paste 121 is spread horizontally over the printing screen 200 and at the same time vertically through the screen openings 202 in the direction of the printing support 210 by means of the doctor blade 215 of the spreading device 214 in such a way that the first electrode sub-layer 111 is formed on the first metallic conductor layer 115.

[0033] In step 402, the first electrode sublayer 111 is dried by heat irradiation for 6 minutes. Due to the high viscosity of the first paste 121, the first electrode sublayer 111 has a nearly cuboid shape after drying 402, with an edge elevation 301 of less than 1 µm and an edge angle 300 of less than 1°.

[0034] In branching step 403, it is determined whether a further electrode sublayer is to be screen-printed. Since this is the case here (“Yes”), the process branches back to step 401. In step 401, the second electrode sublayer 112 of the energy storage device 100 is now formed by screen printing with the second paste 122 on the first electrode sublayer 111. For this purpose, a suitable amount of the second paste 122 is applied to the printing screen 200 by means of the second application device 222. Subsequently, as in Fig. 3, by means of the doctor blade 215 of the spreading device 214, the applied second paste 122 is spread horizontally over the printing screen 200 and at the same time vertically through the screen openings 202 in the direction of the printing support 210 in such a way that the second electrode sub-layer 112 is formed on the first electrode sub-layer 111.

[0035] Subsequently, in step 402, the second electrode sublayer 112 is dried by heat irradiation for 6 minutes. After drying 402, the first electrode layer 101 thus formed also has an overall nearly cuboid shape with an edge elevation 301 of less than 5 µm and an edge angle 300 of less than 5°.

[0036] In branching step 403, it is checked again whether another electrode sublayer is to be screen-printed. Since this is no longer the case (“N”), the method continues with step 404. In step 404, the separator layer 110 of the energy storage device 100 is screen-printed on the second electrode sublayer 112 by screen-printing with a third paste. For this purpose, the third paste is prepared from the porous separator material and binder with an epoxy resin and diethylene glycol monobutyl ether ester as solvent, wherein the composition of the binder and the solvent content are adjusted such that the third paste has a rest viscosity of 200 Pa s and a shear viscosity of 50 Pa s. This screen-printing process is preferably also carried out using the screen-printing device 212 from Fig. 2 carried out.

[0037] Subsequently, in step 405, the separator layer 110 is dried by heat irradiation for 6 minutes. After drying 405, the separator layer 110 thus formed also has an overall nearly cuboid shape with an edge elevation 301 of less than 5 µm and an edge angle 300 of less than 5°.

[0038] In step 406, the second electrode layer 114 of the energy storage device 100 is formed by screen printing with a fourth paste on the separator layer 110. The fourth paste is prepared for this purpose from the intended metallic material, such as lithium or sodium, and a binder. This screen printing process is preferably also carried out using the screen printing device 212. Fig. 2. Subsequently, in step 409, the second electrode layer 114 is dried by heat irradiation for 6 minutes.

[0039] In step 410, the second metallic conductor layer 116 of the energy storage device 100 is formed by screen printing with a fifth paste on the second electrode layer 114. The fifth paste is prepared for this purpose from the intended metallic material, such as nickel and binder. This screen printing process is preferably also carried out using the screen printing device 212. Fig. 2. Subsequently, in step 411, the second metallic conductor layer 116 is dried by heat irradiation for 6 minutes. In step 412, the resulting cell element 102 with the metallic conductor layers 115, 116 is arranged in a foil bag as a housing 106, and the housing 106 is filled with a liquid electrolyte. In step 413, the housing is tightly sealed in such a way that the ends of the metallic conductor layers 115, 116 are led out into the exterior space for electrical contact with the energy storage device 100.

[0040] Next, the production of another embodiment of an energy storage device 100 according to a further method will be described with reference to Fig. 5A to 5S, in which the respective steps AS of the method are schematically illustrated. Insofar as the steps are screen printing steps, these can be carried out, for example, using the Fig. 2 shown screen printing device 212.

[0041] In a Fig. In step A shown in Figure 5A, a housing base 501 of the energy storage device 100 is screen-printed on a printing support (not shown), which can be used as the printing support 210 of the screen-printing device 212. For this purpose, a paste that can be polymerized by thermal radiation into an electrically non-conductive material, which will be assumed to be polyethylene in the following, is used. The resulting housing base 501 is a substantially cuboid-shaped layer approximately 200 µm to 500 µm thick.

[0042] In step B - shown in Fig. 5B - the housing base 501 is treated with heat radiation 599 for a period of approximately 6 minutes in order to carry out the polymerization of the polyethylene.

[0043] In step C - shown in Fig. 5C - a 10 µm thick first metallic conductor layer 115 made of nickel is applied to the housing base 501 by deposition or screen printing with a suitable paste. Near the edge of the housing base 501, a strip-shaped, circumferential housing side wall region, in which a first contacting region 512 and, opposite this, a second contacting region 510 for contacting the energy storage device 100 are located, remains uncovered - except for the first contacting region 512, in which the first metallic conductor layer 115 extends essentially to the edge of the housing base 501.

[0044] In step D - shown in Fig. 5D - the first metallic conductor layer 115 is dried with heat radiation 599. The duration of the irradiation, as in subsequent irradiation steps, is also approximately 6 minutes.

[0045] In step E - shown in Fig. 5E - a first electrode sub-layer 111 with a thickness of approximately 100 µm is applied by screen printing onto the first metallic conductor layer 115, leaving the first contacting area 512 omitted. The paste used for this purpose has the same composition and has the same properties as the paste used with respect to Fig. 1 to 3 already described first paste 121, which is why a further explanation of the composition is omitted here. In step F - shown in Fig. 5F - the first electrode sublayer 111 is dried with heat radiation 599.

[0046] In step G - shown in Fig. 5G - a second electrode sub-layer 112 with a thickness of approximately 50 µm is applied by screen printing onto the first electrode sub-layer 111. The paste used for this purpose has the same composition and has the same properties as the paste used with regard to Fig. 1 to 3, but instead of an admixture of a porous separator material, it contains a corresponding portion of an ionic conductor. The first and second electrode sublayers 111, 112 together form a first electrode layer 101 of the energy storage device 100. In step H - shown in Fig. 5H - the second electrode sublayer 112 is dried with heat radiation 599.

[0047] In Step I - shown in Fig. 5I - a separator layer 110 made of a solid electrolyte material with a thickness of approximately 10 µm to 30 µm is applied by screen printing to the second electrode sublayer 112. The solid electrolyte material contains the same proportion of ionic conductor as the second electrode sublayer 112, resulting in a concentration gradient of the ionic conductor from the second electrode sublayer 112 into the separator layer 110. In step J - shown in Fig. 5J - the second separator layer 110 is dried with heat radiation 599.

[0048] In step K - shown in Fig. 5K - in the circumferential housing side wall area, including an inner section of the first contacting area 512, a circumferential housing side wall 502 is applied to the housing base 501 or the first metallic conductor layer 115 by screen printing with the same material that was used for the housing base 501 in step A. In the outer section of the first contacting area 512, the first metallic conductor layer 115 remains exposed. The upper edge of the housing side wall 502 is aligned with the upper edge of the separator layer 110 in an inner section of the second contacting area 510, while in the remaining sections it is approximately 10 µm higher than the upper edge of the separator layer 110. In step L - shown in Fig. 5L - the housing side wall 502 is dried with heat radiation 599.

[0049] In step M - shown in Fig. 5M - a second electrode layer 114 is applied by screen printing a metallic material, which may be lithium, sodium, or another alkali metal, onto the separator layer 110 and the inner portion of the second contacting region 510. The second electrode layer 114 is approximately 10 µm thick, so that it is flush with the upper edge of the housing side wall 502. In step N - shown in Fig. 5N - the second electrode layer 114 is dried with heat radiation 599. Alternatively to producing the second electrode layer 114 by screen printing in steps M and N, the second electrode layer 114 can also be applied by spraying.

[0050] In step O - shown in Fig. 5O - an approximately 10 µm thick second metallic conductor layer 116 made of nickel is applied in the second contacting area 510 by screen printing with a suitable paste. The second metallic conductor layer 116 lies directly on the housing side wall 502 in the outer section of the second contacting area 510, and on the second electrode layer 114 in the inner section of the second contacting area 510, but is mechanically supported by the housing side wall 502 throughout the entire second contacting area 510. In step P - shown in Fig. 5P - a height adjustment layer 503 with a thickness of 10 µm is screen-printed onto the still exposed portions of the second electrode layer 114 and the housing side wall 502 using the same material as was used for the housing bottom 501 and the housing side wall 502. In step Q - shown in Fig. 5Q - the second metallic conductor layer 116 and the height compensation layer 503 are dried or polymerized with heat radiation 599.

[0051] In step R - shown in Fig. 5R - a cuboid housing cover 504 with a thickness of approximately 200 µm is applied by screen printing with the same material that was used for the housing base 501, the housing side wall 502 and the height adjustment layer 503, onto the height adjustment layer 503 and - leaving out the outer portion of the second contacting area 510 - the second metallic conductor layer 116. In step S - shown in Fig. 5S - the housing cover 504 is dried or polymerized with heat radiation 599.

[0052] The manufactured energy storage device 100 can be electrically contacted from above by the ends of the first metallic conductor layer 115 and the second metallic conductor layer 116 which are respectively exposed in the outer sections of the first contacting region 512 and the second contacting region 510, wherein mechanical stresses are diverted into the housing without impairing the cell element 102.

[0053] Fig. 6 shows another energy storage device 100 which has a similar structure, but not just a single cell element 102, but a cell stack 104 with several cell elements 102, 102', 102" electrically connected in series. The energy storage device 100 can be manufactured using a manufacturing process which is largely comparable to that described with reference to Fig. 5A to 5S. To avoid repetition, only the differences are presented below.

[0054] After the procedural steps as in Fig. 5A to 5J, is carried out similarly to Fig. 5K, a housing side wall 502 is formed, which, however, projects entirely beyond the separator layer 110 by 10 µm. Subsequently, a second electrode layer 114 is formed similarly to Fig. 5M shown, is applied to the separator layer 110, but not to the housing side wall 502, so that the housing side wall 502 and the separator layer 110 are flush with each other at the top.

[0055] Thereafter, a third metallic conductor layer 117 is applied to the second electrode layer 114 and an inner portion of the housing side wall 502 that adjoins it in a ring, which can be done in the same way as in the previous embodiment for the second metallic conductor layer 116. Then, in order to form a second cell element 102' of the cell stack, the Fig. 5E to 5J, the process steps corresponding to those shown in FIGS. 5E to 5J are repeated, wherein the first electrode sublayer 111 of the second cell element 102' is applied to the third metallic conductor layer 117. In the manner described, as in Fig. 6, three or more cell elements 102, 102', 102" are formed, which are electrically connected in series with one another via intermediate metallic conductor layers 117 and are separated from one another with respect to ionic conductors.

Claims

[1] Method for producing an energy storage device (100), comprising the following steps: Arranging a printing screen (200) over a printing support (210) which is designed to support a cell element (102) or cell stack (104) of the energy storage device (100); Applying a paste (121; 122) having a rest viscosity of at least 200 Pa s to the printing screen (200); and Spreading the paste (121; 122) through screen openings (202) of the printing screen (200) in order to form an electrode layer (101) of the cell element (102) or cell stack (104) on the printing support (210), wherein the electrode layer (101) is formed with an elevation (301) of at most 5 µm and / or with an edge angle (300) of at most 5°. [2] Method according to claim 1, wherein the rest viscosity of the paste (121; 122) is at most 250 Pa s. [3] Method according to claim 1 or 2, wherein a shear viscosity of the paste (121; 122) during the spreading over the printing screen (200) and at the same time through the screen openings (202) in the direction of the printing support (210) such that the electrode layer (101) is formed on the printing support (210) is at most 50 Pa s. [4] Method according to one of the preceding claims, wherein the paste (121; 122) comprises a binder with an epoxy resin and a solvent. [5] The method of claim 4, wherein the solvent comprises diethylene glycol monobutyl ether acetate. [6] Method according to one of the preceding claims, wherein the electrode layer (101) is formed with a thickness of at least 100 µm, in particular at least 150 µm. [7] Method according to one of the preceding claims, wherein the electrode layer (101) is formed with an elevation (301) of at most 5 µm, in particular at most 1 µm. [8] Method according to one of the preceding claims, wherein the electrode layer (101) is formed with an edge angle (300) of at most 5°, in particular at most 1°. [9] Method according to one of the preceding claims, further comprising a step of drying the electrode layer (101) for a drying time of at most 10 minutes, in particular at most 6 minutes. [10] A method according to any one of the preceding claims, wherein the steps of applying and painting are repeated to form a first electrode sub-layer (111) and a second electrode sub-layer (112) of the electrode layer (101). [11] A method according to any one of the preceding claims, wherein the steps of applying and coating are repeated to form a separator layer (110) of the cell element (102) or cell stack (104) which separates the electrode layer (101) from a further electrode layer (114) of the cell element (102) or cell stack (104). [12] Method according to one of the preceding claims, further comprising the following steps: Arranging the cell element (102) or cell stack (104) in a housing (106); filling the housing (106) with a liquid electrolyte; and Closing the housing (106).

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