DE102020213462A1 - Process for manufacturing a battery cell - Google Patents

Abstract

The invention relates to a method (2) for producing a battery cell (4), in particular a pouch cell, having an electrode stack (6) with a number of first and second current conductors (8, 10), and a cell housing ( 150), in which the first current conductors (8) are joined to form a common cathode (62) and the second current conductors (10) to form a common anode (64) without melting, in which the electrode stack (6) is divided into two housing halves (104) is used, the cathode (62) and the anode (64) protruding at least partially from the housing halves (104), and the housing halves (104) each have a pre-fixed pre-sealing tape in the areas of the cathode (62) and the anode (64). (106, 108), in which the housing halves (104) are bonded to the cell housing (150) all the way around, and in which the cell housing (150) is sealed in the region of the cathode (62) and/or anode (64) a joining process is carried out, in which the cathode (62) and/or the anode (64) are joined to the respective pre-sealing bands (106, 108) in a cohesive manner.

Description

The invention relates to a method for producing a battery cell, in particular for producing a pouch cell, having an electrode stack with a number of first and second current collectors, and a cell housing accommodating the electrode stack. The invention also relates to a device for carrying out the method and a battery cell.

Motor vehicles that are driven or can be driven electrically or by an electric motor, such as electric or hybrid vehicles, generally include an electric motor with which one or both vehicle axles can be driven. To supply electrical energy, the electric motor is usually connected to a vehicle-internal (high-voltage) battery as an electrical energy store.

A battery, in particular an electrochemical battery, is to be understood here and in the following in particular as a so-called secondary battery (secondary battery) of the motor vehicle. In such a (secondary) vehicle battery, chemical energy that has been consumed can be restored by means of an electrical (charging) charging process. Such vehicle batteries are designed, for example, as electrochemical accumulators, in particular as lithium-ion accumulators. In order to generate or provide a sufficiently high operating voltage, such vehicle batteries typically have at least one battery cell module in which several individual battery cells are connected in a modular manner.

The battery cells are designed, for example, as electrochemical (thin) layer cells. The thin-film cells have a layered structure with a cathode layer (cathode) and with an anode layer (anode) and with a separator layer (separator) introduced in between. These components are penetrated, for example, by a liquid electrolyte (liquid electrolyte), which creates an ionically conductive connection between the components or a charge equalization.

To produce battery cells, for example, an active material or electrode material layer is applied to a current conductor. The current conductors are often designed as metal foils, with copper foils typically being used for the anode layers and aluminum foils for the cathode layers. Current collectors coated in this way are used as stacked electrodes (electrode stack). The current conductors of the electrode or cell stack are electrically contacted with one another to form a common anode and a common cathode, which are also referred to below as current collectors.

In order to protect the electrode stack against the ingress of moisture and/or dirt and, on the other hand, to prevent chemicals or the liquid electrolyte from escaping in the event of damage to the battery cell, a cell housing is generally provided as a casing. The cell housing is designed, for example, as an aluminum composite film with polypropylene (PP), battery cells with such a flexible or film-like cell housing (pouch, bag) also being referred to as pouch or soft pack cells.

With regard to the tightness of the cell housing, the electrical connection areas, in which the anode and the cathode are guided out of the cell housing, are prone to leaks.

In particular for applications in vehicle batteries of electrically driven or drivable motor vehicles, rapid charging of the battery cells is desirable in order to keep the downtime of the motor vehicle as short as possible when the vehicle battery is (recharged) charged. Due to the tightness, the resulting gases accumulate inside the cell housing and thus cause an increase in volume or volume expansion of the cell housing. During a rapid charging process, large changes in the volume of the battery cell occur within a short period of time, resulting in mechanical stress in the connection areas. The joint connection between the plastic of the cell housing and the metal surfaces of the cathode or anode is often comparatively weak, so that the stresses that occur can lead to leakage and irreversible damage to the battery cell.

In order to lead the collectors out of the cell housing in pouch cells, it is necessary, for example, from the DE 10 2014 019 505 A1 known to weld the collectors, for example by means of laser or ultrasound, each with a metal strip. The metal strip is made, for example, from a nickel alloy base, and has an adhesive strip which is conventionally made from a polypropylene material. The adhesive strip is also referred to as a pre-sealing tape, for example.

The adhesive strip is sealed to the cell case by heating to 180°C. The heating or the heat-sealing process melts the polypropylene of the cell housing and the adhesive strip, creating a tight connection. The disadvantage of the metal strip with adhesive strips as an additional component is comparatively expensive. Furthermore, laser welding of the metal strip to the collector causes the adhesive strip to heat up, which reduces the ability of the adhesive strip to connect to the metal strip and thus reduces the tightness. Furthermore, the metal strip increases the structural weight of the battery cell. Currently it is not possible to remove the metal strips as the adhesive strip cannot connect the collector directly to the bag.

The current conductors are welded to the collectors, for example by means of laser welding. With laser welding, only a small area of the collector is welded with a line seam. Other areas of the collector are not welded. Since only local welding is carried out, this area heats up more quickly, since during operation all the electrons in the battery current flow through this weld seam area when entering or exiting the electrode.

The resistance in the laser weld is many times higher than the resistance of the collector material (copper or aluminum). This means that there is a (resistive) power loss in the area of the laser weld. The resistance during welding can be reduced if, instead of seam welding in line form, the collector can be welded over the entire surface. However, welding over the entire surface of the collector is not possible because the metal strip is attached to the collector with adhesive strips. The adhesive strip is not able to withstand high temperatures due to the surface welding.

Laser welding is an energy-intensive process. It melts the collector like copper and aluminum which are highly conductive materials. The heat generated during welding can be transferred to the active material and also leads to a high heat impact zone on the collector.

Alternatively, it is possible, for example, to connect the collector and the metal strip (with adhesive strips) by ultrasonic welding. The disadvantage here, however, is that (mechanical) vibrations occur, which cause a tolerance imbalance in the stack and also deformation of the (current) conductor foils. Furthermore, ultrasonic welding is highly dependent on the surface quality of the collector. The presence of oxide, moisture, dirt or an oil film can significantly degrade the quality of the weld.

A combination of aluminum and copper in the battery cell can cause galvanic corrosion, which leads to intermetallic compounds that reduce the conductivity of the collector.

In order to solve the above problems, it is possible, for example, to increase the tolerance of the heat-affected zones in the area of the collector. This necessitates longer collector lengths so that the laser welding can be carried out further away from the active material and the adhesive strip.

From the WO 2012/157892 A2 and the DE 10 2017 217 676 A1 it is known, for example, to carry out a heat-sealing process to seal the cell housing in the region of the collector.

The invention is based on the object of specifying a particularly suitable method for producing a battery cell. In particular, an alternative to the concept of laser welding the collector to a metal strip with adhesive tape is to be provided, which allows for a leakproof sealing of the cell housing. The invention is also based on the object of specifying a particularly suitable device for carrying out the method and a particularly suitable battery cell.

With regard to the method, the object is achieved with the features of claim 1 and with regard to the device 10 and with regard to the battery cell with the features of claim 11. Advantageous refinements and developments are the subject of the respective dependent claims.

Insofar as method steps are described below, advantageous configurations for the device result in particular from the fact that it is designed to carry out one or more of these method steps.

The method according to the invention is intended for the production of a battery cell and is suitable and configured for this. In this case, the battery cell is in particular a pouch, pouch or soft pack cell. The battery cell has a cell housing and an electrode stack accommodated therein with a number of first and second current conductors.

The electrode stack has a number of thin-film cells arranged stacked one on top of the other, with a cathode layer and with an anode layer and with a separator layer (separator) introduced between them. In this case, for example, an active material or electrode material layer is applied to the current collector. The current collectors are designed, for example, as metal foils, copper foils being used suitably for the anode layers and aluminum foils for the cathode layers. Highly silicon-based anode layers are preferably used in this case in order to implement a battery cell with the highest possible power density and, on the other hand, to enable rapid charging of the battery cell. In the following, the first current conductors are to be understood in particular as aluminum foils and the second current conductors are in particular copper foils.

According to the method, the first current collectors are joined to form a common cathode and the second current collectors to form a common anode without melting. In this context, “melt-free” or “melt-free” is understood to mean in particular an integral joining without one or both joining partners going into a melting phase. This means that the joining partners are not melted as much as possible during the joining process.

A "material connection" or a "material connection" between at least two parts connected to one another is understood here and in the following in particular to mean that the parts connected to one another at their contact surfaces through material union or crosslinking (e.g. due to atomic or molecular bonding forces) may be under the effect an additive are held together.

The contacted electrode stack is then inserted into two housing halves, with the cathode and the anode protruding at least partially from the housing halves as connection areas of the battery cell. The housing halves each have a pre-fixed pre-sealing tape in the area of the cathode or anode.

“Pre-fixed” or “pre-fixation” is to be understood here in particular as holding or fastening the pre-sealing tape in a pre-assembly state, ie in a (delivery) position or transport position. In other words, the pre-sealing tape is held in a pre-positioned position on the respective housing half.

The housing halves are bonded to the cell housing all the way around. The housing halves are joined, for example, with a defined pressure and with a defined (sealing) time and a defined (sealing) temperature in a heat-sealing process, so that a circumferential, edge-side, sealing seam is produced as a joint.

In order to seal the cell housing, it is provided according to the invention that a joining process is carried out in the region of the cathode and/or anode, in which the cathode and/or the anode are joined to the respective pre-sealing strips in a materially bonded manner. A particularly suitable method for producing a battery cell is thereby implemented.

The order in which the cell housing and the pre-sealing strips are joined is not important here. For example, the housing halves are first joined to form the cell housing and then the anode/cathode with the respective pre-sealing tape. It is also conceivable, for example, to first connect the anode/cathode to the respective pre-sealing strip in the housing halves and then to join the housing halves all the way around to form the cell housing.

The conjunction “and/or” is to be understood here and in the following in such a way that the features linked by means of this conjunction can be designed both together and as alternatives to one another.

In an advantageous embodiment, the first and second current conductors are joined to form the cathode and anode by means of solid-state welding, in particular by means of hot pressure welding. In other words, the collectors are joined by a solid state welding method such as hot pressure welding. The collectors, ie the anode and the cathode, are preferably trimmed to the final dimensions during the solid-state welding process.

The method according to the invention eliminates the need for additional metal strips with adhesive strips, which makes it possible to connect the collectors using a solid-state welding process (hot pressure welding). This means that, in contrast to the prior art, the connection originates purely from the collector. This reduces the heat input into the electrode stack or onto the active layers (cathode layer, anode layer). The solid-state welding of the collector leads to a surface weld and not to a line seam weld as with laser welding. In comparison to a laser weld seam, this enables (large) surface contact and connection of the current collector, which advantageously reduces ohmic heat losses in battery operation.

“Solid body welding” or a “solid body welding process” is to be understood in particular as a joining process in which the joint is created by the application of pressure alone or by a combination of heat and pressure. When heat is used, the temperature in this process is below the melting point of the metals being welded. Furthermore, no additional material is used.

Solid-state welding is understood to mean, for example, diffusion welding in which the joining partners are held together under pressure at elevated temperature and the parts fuse by solid-state diffusion. In the method according to the invention, pressure or friction welding is preferably used as solid-state welding, in which the joining area of the metal joining partners is heated by friction and joined under pressure.

The first and second current conductors are suitably cleaned before the contact is made or before the non-melting, materially bonded joining. In other words, the current conductors are freed from dirt on the surface. For example, the surfaces of the current conductors are freed from contamination using plasma cleaning. In a preferred embodiment, the first and second current collectors are cleaned in particular in an ultrasonic bath before joining or solid-state welding. This ensures that there is as little contamination as possible in the joining area. The clean surfaces improve the quality of the joint and thus the quality of the electrical contact.

In order to prevent galvanic corrosion, the anode and/or the cathode are provided with a protective layer in an expedient development after the non-melting joining. In particular, tinning is applied to the copper side, ie the anode side, immediately after solid-state or pressure welding. In other words, the anode is provided with a layer of tin as a protective layer. Alternatively, for example, a nickel coating of the anode is also conceivable.

An additional or further aspect of the invention provides that a multi-layer pre-sealing tape is used with a metal layer and a plastic layer and with an insulating layer arranged in between, the metal layer facing the cathode or anode and the plastic layer facing the housing half.

In contrast to the prior art, the pre-sealing tape or the adhesive strip according to the invention is not made exclusively from polypropylene. The pre-sealing tape according to the invention has three base layers which are joined together to form a pre-sealing tape, for example in a roll lamination process. The first layer consists of metal (copper or aluminum) and has a layer thickness of about 0.05 mm (millimeters), for example. The second layer is made of a plastic material such as polypropylene (PP) or polyester (PET) and has a layer thickness of 0.1 mm, for example. A silicone-based adhesive is preferably used as the insulating layer to connect the metal layer to the plastic layer. The insulating layer is preferably temperature-resistant up to 200°C (degrees Celsius).

In a suitable embodiment, a metal layer matched to the cathode or anode is used. This means that the pre-sealing tape according to the invention is provided in two types or designs. A copper layer is used as the metal layer for the anode, with an aluminum layer correspondingly being used as the metal layer for the cathode. The metal layer is therefore preferably made from the same material as the associated collector material. In this case, the housing half suitably also has the plastic material, at least in part. This is a reliable and tight material connection between the plastic layer and the housing half on the one hand and the metal layer and the respective collector on the other hand can be realized, with the plastic layer and the housing half being bonded in the course of the circumferential heat-sealing process, and with the metal layer and the respective collector being bonded in the additional joining process .

In an advantageous development, electromagnetic pulse welding (EMP welding) is used as the joining process for the materially bonded connection of the collectors with the respective pre-sealing strips, which joins the metal layer with the respective collector material. This means that a magnetic forming takes place, in which one of the joining partners experiences a non-contact impulse by means of a magnetic field and collides with the other partner. Due to the high speed when the joining partners collide, a material bond is formed in the solid phase, as in explosive welding. Only a small amount of heat is introduced by the EMP welding, so that essentially no thermal distortion of the cell housing and/or the collectors occurs.

The cell housing is designed, for example, as an aluminum composite film with polypropylene (PP) and/or polyester (PET). In a preferred embodiment, the housing halves are produced by means of a deep-drawing process, with the pre-sealing strips being pre-fixed to the housing halves in the course of the deep-drawing process. This means that the pre-seal bands are attached directly to the pouch cell during the thermoforming process.

For this purpose, the pre-sealing tape is connected to the housing half, for example, by means of double-sided adhesive tape (with hot-melt adhesive). For this purpose, the pre-sealing tape has, for example, an additional layer of hot-melt adhesive with a layer thickness of approximately 0.01 mm on the plastic layer in order to attach the pre-sealing tape to the housing half.

In an additional or alternative development, a texture is embossed into the housing halves to pre-fix the pre-sealing tape. This means that a texture is preferably produced on the housing half during the deep-drawing process, which improves the adhesion between the housing half and the pre-sealing tape. In this development, in particular, no additional adhesive layer with hot-melt adhesive is required on the plastic layer.

The device according to the invention is intended for carrying out a method described above and is suitable and set up for this. The explanations in connection with the method also apply to the device and vice versa. As a result, a particularly suitable device for producing a battery cell is realized.

The battery cell according to the invention is designed in particular as a pouch cell. The battery cell is provided, for example, for use in a vehicle battery of an electrically driven or drivable motor vehicle.

The battery cell has an electrode stack with a number of first and second current conductors, and a cell housing accommodating the electrode stack. The first current collectors are joined to form a common cathode and the second current collectors to form a common anode without melting, the cell housing having two circumferentially joined housing halves, from which the cathode and the anode protrude at least partially. The housing halves each have a pre-sealing band in the areas of the cathode and the anode, which is joined to the respective collector in a materially bonded manner. A particularly suitable battery cell is thereby realized. The advantages and configurations given with regard to the method and/or the device can also be transferred to the battery cell and vice versa.

• 1 ein Flussdiagramm eines erfindungsgemäßen Verfahrens zur Herstellung einer Batteriezelle,
• 2 einen Reinigungsprozess des Verfahrens,
• 3 einen Vorerwärmungsprozess des Verfahrens,
• 4 einen Druckschweißprozess des Verfahrens zur Kontaktierung eines Kollektors,
• 5 einen Abtrennvorgang des Druckschweißprozesses,
• 6 einen Beschichtungsvorgang des Verfahrens,
• 7 ein Vorsiegelband für eine Kathode und für eine Anode,
• 8 einen Prägeprozess zur Erzeugung einer Textur an einer Gehäusehälfte
• 9 einen Fügeprozess zur Vorfixierung des Vorsiegelbands auf der Gehäusehälfte,
• 10 die Gehäusehälfte mit der Textur und mit dem Vorsiegelband,
• 11, 12 einen alternativen einen Fügeprozess zur Vorfixierung des Vorsiegelbands auf der Gehäusehälfte,
• 13 die Gehäusehälfte mit dem Vorsiegelband,
• 14 einen Heißsiegelprozess des Verfahrens,
• 15 die Batteriezelle in einer Seitenansicht,
• 16, 17 einen Fügeprozess zur stoffschlüssigen Verbindung der Vorsiegelbänder mit einem Kollektor,
• 18 eine alternative Ausführung des Vorsiegelbandes für eine Kathode und für eine Anode, und
• 19 einen alternativen Fügeprozess des Verfahrens zur Kontaktierung des Kollektors.

Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. It shows in schematic and simplified representations:

• 1 a flow chart of a method according to the invention for producing a battery cell,
• 2 a cleaning process of the procedure,
• 3 a preheating process of the method,
• 4 a pressure welding process of the method for contacting a collector,
• 5 a separation process of the pressure welding process,
• 6 a coating operation of the method,
• 7 a pre-sealing tape for a cathode and for an anode,
• 8th an embossing process to create a texture on a case half
• 9 a joining process for pre-fixing the pre-sealing tape on the housing half,
• 10 the case half with the texture and with the pre-sealing tape,
• 11 , 12 an alternative joining process for pre-fixing the pre-sealing tape on the housing half,
• 13 the case half with the pre-sealing tape,
• 14 a heat sealing process of the method,
• 15 the battery cell in a side view,
• 16 , 17 a joining process for the material connection of the pre-sealing tapes with a collector,
• 18 an alternative embodiment of the pre-sealing tape for a cathode and for an anode, and
• 19 an alternative joining process of the method for contacting the collector.

Corresponding parts and sizes are always provided with the same reference symbols in all figures.

the 1 shows a method 2 according to the invention for producing a battery cell 4 ( 15 ). The following based on the 2 until 19 In this embodiment, the method described essentially has nine consecutive method steps OP1, . . . , OP9. An unspecified device for carrying out the method 2 or the method steps OP1, ..., OP9 is also based on the below 2 until 19 explained in more detail.

The battery cell 4 has an electrode or cell stack 6 with a number of thin-film cells arranged stacked one on top of the other with a cathode layer and with an anode layer and with a separator layer (separator) introduced in between. In this case, for example, an active material or electrode material layer is applied to a current conductor 8, 10 in each case. The current conductors 8, 10 are designed, for example, as metal foils, copper foils being used suitably for the anode layers and aluminum foils for the cathode layers. The current conductors 8, 10 project over the edge of the electrode stack 6. In the following, the current conductors 8 are to be understood in particular as aluminum foils and the current conductors 10 are in particular copper foils.

the 2 shows the method step OP1 of the method 2 in successive representations. In the method step OP1, the surface of the current conductors 8, 10 is cleaned by means of ultrasound. During surface cleaning, oxides, moisture and oily products are removed from the surface of the current conductors 8, 10.

The device has an ultrasonic cleaner 12 with an ultrasonic bath 14 for this purpose. An ultrasonic generator 16 for frequencies up to 40 kHz (kilohertz) is arranged in the ultrasonic bath 14 , the ultrasonic bath 14 being filled with a liquid 18 . The liquid 18 is, for example, distilled water with alkaline solvents or additives for oxide cleaning. During operation, the ultrasonic generator 16 generates an ultrasonic wave 20, which has the greatest amplitude in the area of the immersed conductors 8, 10. The ultrasonic wave 20 generates rapidly moving cavitation bubbles 22 in the liquid 18, which move at the ultrasonic frequency and remove dirt and oily substances from the surfaces of the current conductors 8, 10. The alkaline additives in Fluid 18 help remove surface oxides.

The ultrasonic bath 14 is covered with a cover 24 . The cover 24 is made of rubber and has slots for guiding the current conductors 8, 10. In the area of the cover 24, cleaning roller brushes 26 with polyamide fibers are provided for the mechanical cleaning of the current conductors 8, 10. The cleaning roller brushes 26 are moved by contact with the current conductors 8, 10.

The electrode stack 6 is fixed by a gripper 28 in a guide plate 30 for the ultrasonic cleaning. The electrode stack 6 is lowered by means of the guide plate 30 so that the current collector 8 is immersed through the slotted cover 24 into the ultrasonic bath 14 and is cleaned of the cavitation bubbles 22 and the cleaning roller brushes 26 . The electrode stack 6 is then moved vertically upwards by means of a gripper 32 and pivoted through 180° by means of a joint 34 . The current collector 10 is then immersed in the ultrasonic bath 14 and cleaned. The electrode stack 6 is accommodated in a protective cover 36 so that no liquid 18 can reach the electrode stack 6 if possible. Finally, the electrode stack 6 is removed from the guide plate 30 by a gripper 38 and guided to the method step OP2.

As an alternative to method step OP1, it is conceivable, for example, to clean current conductors 8, 10 by means of a plasma.

Once the surface is cleaned, it is preheated in process step OP2 using induction or resistance heating under an inert nitrogen atmosphere. In the case of resistance heating, for example, two stamps that can be energized are pressed against the current arresters 8, 10. In this case, the stamps are made in particular from graphite, titanium or tungsten.

In the case of the copper anode of the current collector 10, the preheating takes place, for example, to up to 600°C. In the case of the aluminum cathode of the current collector 8, the preheating takes place, for example, up to 300°C. The device has a heating chamber 40 for this purpose. The heating chamber 40 has a gas 42 inside.

The inert gas 42 is in the form of nitrogen, for example, and is introduced into the heating chamber 40 under an overpressure of, for example, 15 mbar (millibar). Two cooling plates 44 are provided in order to avoid undesired heating of the electrode stack 6 . The cooling plates 44 are pressed against the electrode stack 6 on both sides by means of a gripper 46 with a clamping force shown as arrows, so that the electrode stack 6 is tempered to a maximum temperature of 50° C. during the preheating. The cooling plates 44 are cooled by a water and glycol suspension, with the temperature being set or regulated using the water cooling rate.

The current conductors 8, 10 are each preheated by means of a heating device 48. The heating device 48 heats the current conductors 8, 10, for example via induction or via an electrical (heating) resistance.

After the preheating or preheating, the current conductors 8, 10 are pressed inside the heating chamber 40 with a heated stamping device 50, 52 in process step OP3. The stamp devices 50, 52 each have a movable (pressure stamp 54) and a fixed stamp 56 as a counter bearing. The stamps 56 are supported on a base plate 58. Both the fixed and the movable stamp 54, 56 are heated by heating cartridges 60, which are a ceramic cover or a ceramic jacket are embedded.

The stamp 54 of the stamping device 50 is heated in particular to a temperature between 350° C. and 600° C., for example up to 400° C., and generates a pressure of, for example, 4 bar to 6 bar on the current collector 8. The stamp 54 of the stamping device 52 is heated in particular to a temperature between 550° C. and 750° C., for example up to 700° C., and generates a pressure of, for example, 6 bar to 7 bar on the current conductor 10. The temperature of the stamp 54 is therefore always lower than the melting temperature of the respective current collector material. The current conductors 8 are joined to form a common cathode 62 by means of the stamping devices 50, 52, and the current conductors 10 are joined to form a common anode 64 without melting and by means of the stamping device 52. In particular, this involves pressure welding, with the force 65 required for the pressure welding being calculated using the following formula: $$\text{surface}\ddot{\text{a}}\text{surface of the collector}*\text{fly}ß\text{starting voltage}\left(\text{approx}.50\text{MPa}\right)*\text{factor}\left(5\text{until}10\right)$$

Suitably, the current collectors 8, 10 are heated to such a temperature that the yield-initiation stress is approximately the same, as a result of which the current collectors 8, 10 can be pressure-welded with substantially the same stamping pressure. At 700°C and 550°C the flow surface of copper and aluminum is about 50 MPa. If lower temperatures are used, the pressure for pressure welding is increased accordingly. The factor (5 to 10) is pre-characterized by means of measurements and is essentially dependent on the degree of cleaning or the surface cleanliness of the current conductors 8, 10. The Pressure welding is also performed under the inert nitrogen atmosphere of gas 42 . As in method step OP2, the electrode stack 6 is cooled to below 50° C. by the cooling plates. During pressure welding, the collectors 62, 64 are held under the heated dies 54, 56 for three to five seconds.

During the pressure welding, the material of the collectors 62, 64 deforms by a maximum of 5%. Due to the shear strain, the remaining oxide layer breaks open and atomic contact between the connecting metals occurs. The material is welded using the solid state diffusion process. It is essential that the material is not melted during this welding process and that no intermetallic compounds are therefore formed in the collectors 62, 64.

Then, the joined commutators 62, 64 are also trimmed after completion of the pressure welding. This in 5 The trimming shown for the anode 64 is done in the same stroke as the pressure weld, with collector dimensions within tolerance limits. Advantageously, since the trimming occurs at a higher temperature of the metal being joined, less cutting force is required.

In this case, the stamp 54 has an integrated cutting stamp 66 for separating or trimming the anode 64 . The cutting punch 66 is coupled to a pneumatic system with a spring piston 68 and a spring cylinder head 70 , the spring cylinder head 70 being mounted with the punch 54 on a press ram 72 . The punch 56 is designed with a cutting matrix 74 as a counter bearing for the cutting punch 66, which is provided with a waste chute 76 for the separated material.

An optional method step OP4 is then carried out. In this case, a protective coating is applied to the anode 64 as protection against corrosion. At the in 6 In particular, a tin coating is applied to the copper conductor of the anode 64 as illustrated in method step OP4. For this purpose, the device has a molten tin bath 78 . In a housing 80 of the molten bath 78, heating cartridges 82 are provided for the uniform heating of the molten bath 78, which is between 250° C. and 300° C. The molten pool 78 is covered with a temperature-resistant cover 84 which has slots for the anode 64 .

The optional method step OP4 improves the conductivity and implements galvanic corrosion protection for the anode 64. After the trimming process, the anode or the copper collector 64 is immersed in a molten tin bath. For this purpose, at the beginning of the method step OP4, the electrode stack 6 is fixed in a guide plate 88 by a gripper 86 . The electrode stack 6 is lowered by the guide plate 80 so that the anode 64 is immersed through the slotted cover 84 into the molten tin bath 78 and is coated with a protective layer with a coating thickness of about 0.01 mm. Tin melts at 232°C and the molten tin bath is therefore maintained at 300°C. The coating produced after hot dipping consists of a very thin intermetallic layer, which first forms at the interface of copper and tin and is then followed by a layer of pure tin (approx. 0.01 mm). The electrode stack 6 is then moved vertically upwards by means of a gripper 90 and pivoted through 180° by means of a joint 92 . The coated anode 64 is then cooled to room temperature with a cooling plate 94 .

During the hot dipping of tin it is important that the remainder of the collector is cooled from the hot dipping area. This way the heat is not transferred to the rest of the electrode. In this case, the electrode stack 6 is accommodated in a protective cover 96 for cooling the coating—similarly to method step OP2.

After the solidification of the tin layer, the coated anode 64 is cleaned by means of a tin particle cleaning 98 by means of an air stream, with a suction device 100 being provided. Finally, the electrode stack 6 is removed from the guide plate 88 by a gripper 102 and guided to the method step OP6.

The hot dipping of tin, as in the previous operations, is also carried out under an oxygen-free environment (preferably under nitrogen). Although there is no layer of tin on aluminum, it is also advisable to cool the aluminum collector or cathode 62 to room temperature using a cooling plate, not shown in detail. Tin reduces the oxidation of copper once the electrode stacks leave a nitrogen-rich environment.

On the one hand, the tin coating prevents oxidation of copper at the anode 64. On the other hand, galvanic corrosion is prevented when copper is bonded to aluminum. Tin reduces the voltage difference between aluminum and copper, thus slowing down galvanic corrosion.

Instead of a tin coating, for example, a nickel coating is also conceivable.

After method step OP4, the electrode stacks 4 are placed in deep-drawn bags or housing halves (bag half shells) 104. Two pre-sealing strips 106, 108 are attached to the housing half 104 designed as a deep-drawn bag.

The pre-sealing tapes 106, 108 are provided in a method step OP5. Below are based on the 7 two embodiments of the pre-sealing tapes 106, 108 are explained in more detail.

The pre-sealing tapes 106, 108 have a multilayer structure with a metal layer 110, 112 and with an insulation layer 114 and with a plastic layer 116. The metal layer 110, 112 has a layer thickness of 0.05 mm. In the case of the pre-sealing tape 106, the metal layer 110 is in the form of an aluminum plate and in the case of the pre-sealing tape 108 the metal layer 112 is in the form of a copper plate. The pre-sealing tape 106 is used for the cathode 62 and the pre-sealing tape 108 for the anode 64 .

The metal layers 110, 112 are attached to a polypropylene strip as a plastic layer 116. The plastic or polypropylene layer has a layer thickness of about 0.1 mm. A silicone-based adhesive is provided as the insulating layer 114 to attach the layers 110 , 112 , 114 . Silicone can withstand up to 200°C and also acts as an insulator. The copper used for the copper layer 112 consists of 99.99% E-copper and the aluminum of the aluminum layer 110 consists of more than 99.3% pure aluminum.

In the second embodiment, the pre-sealing tapes 106, 108 each have a further layer 118. The layer 118 is designed as a hot-melt adhesive applied to the polypropylene 116 . The layer 118, which is designed in particular as a hot-melt adhesive, has a layer thickness of 0.01 mm and has an adhesive effect on both sides. The purpose of this fourth layer 118 is to attach the pre-sealing tapes 106, 108 to the housing half 104. This will be explained below. The hot melt adhesives of layer 118 melt at about 100°C.

The following is based on the 8th until 10 a first exemplary embodiment for the method steps OP6 and OP7 is explained in more detail, in which preferably pre-sealing tapes 106, 108 without the layer 118 are used.

In the process step OP6 takes place in the 8th shown deep-drawing process, with which an aluminum composite foil is deep-drawn into the housing half 104. For this purpose, the device has a die 118 with a cavity 120 as a negative mold for the housing half 104 . The aluminum composite foil is positioned as a blank on the die 118 and fixed laterally using sheet metal holders 122 . In this embodiment, the sheet metal holders 122 have an insert 124 which embosses a texture 126 in a flange surface of the housing half 104 . During the deep-drawing process, a punch 128 is lowered and the foil is formed into the cavity 120 .

During the deep-drawing process, the texture 126 is pressed into foil, where the pre-sealing tapes 106, 108 are later attached. The texture is produced as insert 124 using a hold-down device. A negative mold of texture 126 is created on the surface of insert 124 . When the insert 124 presses the foil against the die surface, the texture 126 is formed on the foil or shell half 104. FIG. As soon as the insert 124 or the blank holder 122 has exerted its pressure, the (deep-drawing) punch 128 moves downwards and carries out the deep-drawing process.

In the 9 the method step OP7 is shown, during which the pre-sealing tapes 106, 108 are pre-fixed on the housing half 104 and the housing half 104 is cut to size. The device has two magazines 130 from which the pre-sealing tapes 106, 108 are removed. In the 9 only the magazine 130 for the pre-sealing tape 106 is shown as an example.

The deep-drawn bag or the housing half 104 is fixed in the negative cavity 120 of the die 118 in method step OP7. The pre-sealing strip 106, 108 is removed from the magazine 130 and transported to the flange of the housing half 104. The pre-sealing tape 106, 108 is by means a spring-loaded stop 132 of a cutting jaw 134 precisely positioned on the bag flange of the housing half 104 ( 9 left side). The cutting jaw 134 then moves downwards and generates a hold-down pressure on the flange and the pre-sealing band 106, 108 on the die surface ( 9 right side). The pre-sealing tape 106, 108 connects to the bag flange of the housing half 104 by strong adhesion due to the textures 126 produced in process step OP6. In other words, the pre-sealing tape 106, 108 is welded onto the housing flange. A cutting die 136 designed as an upper knife then moves downwards and cuts the bag flange to the correct size with an under knife as counter bearing/knife 138 . This means that operation OP7 applies the preseal tapes 106, 108 to the shell half 104 and also trims the flange to size. The severed or sheared-off separating piece 140 is removed from the die 118 via a ramp 142 .
In the representation of 9 For example, two upper and lower cutters 136, 138 are provided on two sides of the housing half 104. It is also conceivable that an upper and lower cutter 136, 138 is provided on only one side. In other words, the upper and lower cutters 136, 138 are optionally designed on one side or two sides. It is also conceivable, for example, that no upper cutter 136 is provided when the die 118 is moved with the lower cutter 138 against the cutting jaw 134 .

The attachment of the pre-sealing tapes 106, 108 is temporary. The pre-fixing merely ensures that the pre-sealing tapes 106, 108 do not shift from their position on the bag flange during transport for further processing. The pre-sealing bands 106, 108 do not yet have a sealing connection with the bag surface for leak-free sealing. The leak-free sealing of the pre-sealing strips 106, 108 with the two housing halves 104 and the collectors 62, 64 takes place in method step OP8.

the 10 shows two housing halves 104 in a perspective view. The upper housing half 104 is shown after step OP6 in which the texture 126 has been embossed into the flange of the housing half 104, and the lower housing half 104 is shown after step OP7 in which the preseal tapes 106, 108 have been pre-set and the flanges have been trimmed .

The following is based on the 11 until 13 a second exemplary embodiment for method steps OP6 and OP7 is explained in more detail, in which preferably pre-sealing tapes 106, 108 with layer 118 are used.

In the 11 and 12 An alternative embodiment of the method steps OP6 and OP7 for positioning and pre-fixing the pre-sealing strip 106, 108 is shown. In this embodiment, a transport guide 144 is provided from the magazines 130 to the flange. The sheet metal holders 122 have the stops 132 . A spring-loaded punch 146 is mounted on the deep-drawing punch 128 . Furthermore, the upper blade of the cutting punch 136 is mounted on the punch 128 by means of a gas pressure spring 148 . In an alternative embodiment that is not shown, a roll can also be used for the pre-sealing tape 106, 108 instead of the magazines 130, on which the pre-sealing tape 106, 108 is delivered as endless material and is separated or individualized with a knife.

in the in 11 and 12 In the embodiment shown, the aluminum laminate foil lies on the surface of the die 118, the blank holders 122 are lowered down as blank holders and press the foil onto the surface of the die 118. The pre-sealing tape 106, 108 is removed from the magazine 130 via the transport guide 144 positioned against the stop 132, and the stamp 128 is moved downwards as a deep-drawing stamp with a form stamp (stamp 146) for connecting the pre-sealing bands 106, 108 to the housing half 104 and a cutting device (cutting stamp 136, counter bearing 138) for closing off the flange. The first deep-drawing process is carried out by the deep-drawing punch 128 with deformation of the film in the cavity 120. Approximately 1 mm before bottom dead center for the punch press 128, the pre-sealing tapes 106, 108 are pressed with the layer 118 onto the housing half 104 and the flange is trimmed to its final dimensions . In this case, the texture 126 of the flange is omitted, since the hot-melt adhesive layer 114 connects to the flange of the housing half 104 even with slight pressure.

In the execution of 11 and 12 the working process of deep-drawing a housing half 104, final trimming of the bag flange, and attachment of the pre-sealing tape 106, 108 to the bag flange are thus essentially carried out in one operation.

The attachment or pre-fixing of the pre-sealing tapes 106, 108 on the bag flange by means of the layer 118 is provisional and ensures that the pre-sealing tapes 106, 108 during transport to further operation does not shift from the position on the bag flange. The pre-sealing tapes 106, 108 are not yet firmly connected to the surface of the housing half 104 in order to seal the leak tightly.

the 13 shows the housing half 104 in a perspective representation after the method step OP6 according to FIG 11 and 12 , in which the pre-sealing bands 106, 108 were pre-fixed and the flanges were cut to size. The pre-sealing tape 106, 108 is attached to the pouch film of the housing half 104 by the adhesive of the layer 118. The effect of the adhesive is only activated by pressure. In this way, a transport-safe connection between pre-sealing tape 106, 108 and housing half 104 is first created. In a later process, the pre-sealing band 106, 108 is heated and a material connection is produced between the pre-sealing band 106, 108 and the housing half 104.

the 14 1 shows a schematic of a method step OP8, in which the electrode stack 6 is inserted between two housing halves 104 equipped with pre-sealing strips 106, 108. The housing halves 104 are then brought into contact in the area of the edge flanges and joined or sealed by means of a heat-sealing process. During the heat sealing process, a temperature of up to 180°C is applied to the housing halves 104 and pressure is applied. The pressure is in the 14 shown schematically by arrows. The polypropylene of both housing halves 104 is melted with the aid of pressure and temperature. The melting and resolidification of the polypropylene causes a leak-free circumferential seal of the case halves 104, forming a cell case 150 ( 15 ).

Like in the 15 As can be seen comparatively clearly, the electrode stack 6 is completely accommodated in the cell housing 150, with only the anode 64 and the cathode 62 protruding from the cell housing 150. The electrode stack 6 is in this case arranged essentially in one half of the cell housing 150, with the other half acting as a free space or gas pocket 152 in order to absorb gases occurring during operation as a buffer volume.

The heat-sealing process creates a circumferential sealing edge 154 through the material connection of the flanges of the housing halves 104. In the area of the pre-sealing strips 106, 108, a material connection 156 is effected between the housing halves 104 and the plastic layers 116.

the 16 and 17 show a sectional view of the cell housing 150 in the area of the anode 64 ( 16 ) and after ( 17 ) the method step OP9. In method step OP9, metal layer 112 of pre-sealing tape 108 is materially welded or connected to metal anode 64 . The welding is carried out in particular by electromagnetic pulse welding (EMP welding). EMP welding technology is preferred because it causes no heating and produces localized welds between metal layers 112, 64 through atom-to-atom contact. In the EMP welding process, the magnetic pulse moves metal layer 112 of preseal tape 108 toward collector 64 at high speed. This welds metal layer 112 to collector 64, creating a leak-free bond between metal layers 112,64. The resulting material connection 158 is in the 17 shown by lines.

The plastic layer 116 of the pre-sealing strip 106, 108 is therefore particularly intended for heat-sealing with the plastic of the housing half 104, and the metal layer 110, 112 of the pre-sealing strip 106, 108 is particularly intended and suitable for EMP welding with the collectors 62, 64 and furnished.

Alternatively, it is also possible to use an external movement device, which is moved at high speed and produces a weld of the pre-sealing band 108 with the collector 64 by impact. The external device is moved by induced magnetic fields.

Ultrasonic welding is also possible instead of EMP welding. Ultrasonic welding can also join polypropylene. If ultrasonic welding is used, one can avoid the heat sealing process. The housing halves 104 are connected to one another and to the plastic layers 116 and also the metal layers 112 of the pre-sealing strips 106, 108 and the collectors 62, 64 by ultrasonic welding. It is important that after ultrasonic welding, the strength of the weld is checked under vibration load.

The method steps OP8 and OP9 are interchangeable, for example. In other words, the order of OP8 and OP9 can be reversed, and first an EMP welding for the integral connection of the pre-sealing bands 106, 108 with the collectors 62, 64 and then a heat sealing process for the integral connection of the housing halves 104 can take place.

In the case of a battery cell 4 with a liquid electrolyte, this is preferably filled into the gas pocket 152 during method step OP8 or OP9 before the cell housing 150 is completely closed and sealed.

Based on 18 a further alternative embodiment for method step OP9 is explained in more detail below. Here, a layer 160 of conductive adhesive is applied to the metal layer 110, 112 of the pre-sealing tapes 106, 108. the 18 shows schematically the design of the pre-sealing tapes 106, 108 with (right side) and without (left side) the layer 118.

The conductive adhesive of layer 160 is, for example, acrylic with carbon fiber fillers. The conductive adhesive is allowed to melt when the housing halves 104 are heat sealed and, when solidified, provides a strong bond between the metal layers 110, 112 and the respective commutator 62, 64. If this method of bonding is to be used, the preseal tape 106, 108 has four or five layers on. First a 0.02 mm acrylic based conductive adhesive as layer 160, then a 0.05 mm copper/aluminium metal layer as metal layer 110, 112, then a 0.02 mm silicone based adhesive as insulation layer 114, then a polypropylene layer of 0.05 mm as plastic layer 116 and finally optionally a hot melt adhesive with a layer thickness of 0.02 mm as layer 118.

The acrylic based adhesive of layer 160 preferably softens at 170°C so that it can withstand temperatures higher than 180°C heat sealing temperature. The acrylic adhesive is a pressure based adhesive, which means it joins the parts together by applying pressure. The pressure is applied during the heat sealing process. If a higher heat sealing temperature is required, a silicone based adhesive can be used. Silicone based adhesive with a thickness of 0.02mm can withstand temperatures up to 200°C. In the absence of a filter material such as (carbon or graphite/silver or other metal), both acrylic and silicone adhesives can act as an insulator between the metal layer on the preseal tape 106,108 and the collector 62,64.

An epoxy based adhesive (with or without conductive components) could also be used. This adhesive usually has to be cured at higher temperatures. The temperature is specified when heat sealing.

In the 19 An alternative joining method for the non-melting, materially bonded joining of the current conductors 8, 10 to the collectors 62, 64 is shown. In this case, the current conductors 8, 10 are initially freed from dirt in a first method step OP1' by means of ultrasonic cleaning. Then, in a method step OP2', the current conductors 8, 10 are immersed in an adhesive bath 162 and provided with an electrically conductive adhesive layer. Excess adhesive residues are removed by means of an air flow from a blower system 164 . Subsequently, in a method step OP3', pressure is exerted on the stacked conductors 8, 10 via a pressure system 166, and the current conductors 8, 10 are thus joined with the adhesive layers. Finally, in a method step OP4′, the adhesive layers are cured by means of a heating device 168, for example at 150° C., as a result of which the collectors 62, 64 are joined in a cohesive manner. The joining process 19 according to the method steps OP1' to OP4', for example, replaces the method steps OP1 to OP3 of method 2.

As a result of the method 2 according to the invention, no separate metal strip is required to connect the collector 62, 64, as a result of which the manufacturing costs of the battery cell 4 are advantageously reduced. Furthermore, there is no costly and energy-intensive laser welding.

When the collectors 62, 64 are joined, the current conductors 8, 10 do not melt. Therefore, no intermetallic compound is formed when the collectors are joined. The conductivity after welding is as good as that of the base metal. This contributes to reducing the power loss when charging and discharging the battery cell 4 .

The collector foils of the current collectors 8, 10 are cleaned ultrasonically in order to remove dirt, oxide and grease particles. The surface cleaning makes the subsequent weld seam or joint connection stronger. The weld strength is as good as that of the base metal.

According to the method, instead of line welding as in laser welding, there is surface welding by hot pressure welding. Electrons can thus flow over a much larger area inside and outside the battery cell 4 during operation. This leads to less heating of the collector 62, 64. The rate of electron transfer can be very fast, which is helpful in ultra-fast charging.

In particular, the welding and trimming of the commutator 62, 64 is done in the same machine and in a single stroke. This reduces the footprint of the process and the cost of the cutting machine.

The copper collector 64 is plated with tin to prevent oxidation. This increases conductivity and also reduces galvanic corrosion when copper is bonded to aluminum.

Hot pressure welding and tinning is carried out and the closed container of the device is filled with nitrogen. Therefore there is no oxide formation on copper and aluminum. Aluminum preferably has no tin coating. Aluminum will form a stable oxide layer over time. It is possible to stop the oxide formation of aluminum if aluminum is coated with epoxy-based conductive adhesive as a protective layer before it leaves the nitrogen-filled machine chamber.

A leak free connection (helium leak free) between the housing halves 104 and the collectors 62, 64 is made. This is a great advantage when the battery cell 4 has a higher expansion and contraction during charging and discharging. Especially when using a silicon-based anode.

The pre-sealing strips 106, 108 are attached to the housing halves 104 during the deep-drawing process. No additional machinery is required to attach the preseal tapes 106, 108 to the cell housing 150. The pre-sealing strips 106, 108 are located exactly on the flange of the housing halves 104. The cutting or trimming of the deep-drawing process and the introduction of the pre-sealing strips 106, 108 into the housing halves 104 take place in the same stroke. This reduces operating costs and increases accuracy.

The claimed invention is not limited to the embodiments described above. Rather, other variants of the invention can also be derived from this by the 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 of the individual features described in connection with the various exemplary embodiments can also be combined in other ways within the scope of the obvious claims, without departing from the subject matter of the claimed invention.

The designs of the pre-sealing bands 106, 108 are inventive on their own and thus represent an invention in their own right.

Reference List

2

procedure

4

battery cell

6

electrode stack

8th

current conductor (cathode)

10

current collector (anode)

12

ultrasonic cleaner

14

ultrasonic bath

16

ultrasonic generator

18

liquid

20

ultrasonic wave

22

cavitation bubble

24

lid

26

cleaning roller brush

28

gripper

30

guide plate

32

gripper

34

joint

36

protective cover

38

gripper

40

heating chamber

42

gas

44

cooling plate

46

gripper

48

heating device

50, 52

stamp device

54, 56

Rubber stamp

58

base plate

60

cartridge heater

62

cathode, collector

64

anode, collector

65

power

66

cutting stamp

68

spring plunger

70

spring cylinder head

72

press ram

74

cutting die

76

waste chute

78

melt pool

80

Housing

82

cartridge heater

84

lid

86

gripper

88

guide plate

90

gripper

92

joint

94

cooling plate

96

protective cover

98

Tin Particle Cleaning

100

suction

102

gripper

104

case half

106

pre-sealing tape (cathode)

108

pre-sealing tape (anode)

110, 112

metal layer

114

insulation layer

116

plastic layer

118

die

120

cavity

122

sheet metal holder

124

mission

126

texture

128

Rubber stamp

130

magazine

132

attack

134

cutting jaw

136

cutting stamp

138

counter bearing

140

separator

142

ramp

144

transport guide

146

Rubber stamp

148

gas spring

150

cell housing

152

gas bag

154

sealing edge

156

connection

158

connection

160

layer

162

sticky bath

164

blower system

166

printing system

168

heating device

OP1...0P9

process step

OP1,...OP4'

process step

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102014019505 A1 [0009]
• WO 2012/157892 A2 [0017]
• DE 102017217676 A1 [0017]

Claims (11)

Method (2) for producing a battery cell (4), in particular a pouch cell, having an electrode stack (6) with a number of first and second current collectors (8, 10), and a cell housing (150) accommodating the electrode stack (6), - in which the first current conductors (8) are joined to form a common cathode (62) and the second current conductors (10) to form a common anode (64) without melting, - in which the electrode stack (6) is inserted into two housing halves (104), the cathode (62) and the anode (64) protruding at least partially from the housing halves (104), and the housing halves (104) in the areas of the The cathode (62) and the anode (64) each have a pre-fixed pre-sealing tape (106, 108), - In which the housing halves (104) are peripherally bonded to the cell housing (150) and - In which to seal the cell housing (150) in the area of the cathode (62) and/or anode (64), a joining process is carried out, in which the cathode (62) and/or the anode (64) are cohesively bonded to the respective pre-sealing strips ( 106, 108) are joined. Method (2) according to claim 1 , characterized in that the first and second current conductors (8, 10) are joined to the cathode (62) and anode (64) by means of solid-state welding, in particular by means of hot pressure welding. Method (2) according to claim 1 or 2 , characterized in that the first and second current conductors (8, 10) are cleaned in an ultrasonic bath (14) before joining. Method (2) according to one of Claims 1 until 3 , characterized in that the anode (62) and/or the cathode (64) are provided with a protective layer. Method (2) according to one of Claims 1 until 4 , characterized in that a multi-layer pre-sealing tape (106, 108) with a metal layer (110, 112) and with a plastic layer (116) and with an insulating layer (114) arranged in between is used, the metal layer (110, 112) of the cathode (62) or anode (64) and the plastic layer (116) faces the housing half (104). Method (2) according to claim 5 , characterized in that a metal layer (110, 112) adapted to the cathode (62) or anode (64) is used. Method (2) according to one of Claims 1 until 6 , characterized in that electromagnetic pulse welding is used as the joining process for the material connection of the cathode (62) and/or the anode (64) with the respective pre-sealing strips (106, 108). Method (2) according to one of Claims 1 until 7 , characterized in that the housing halves (104) are produced by means of a deep-drawing process, the pre-sealing strips (106, 108) being pre-fixed to the housing halves (104) in the course of the deep-drawing process. Method (2) according to one of Claims 1 until 8th , characterized in that a texture (126) is embossed into the housing halves (104) for pre-fixing the pre-sealing strip (106, 108). Device for carrying out a method (2) according to one of Claims 1 until 9 . Battery cell (4), in particular pouch cell, having an electrode stack (6) with a number of first and second current conductors (8, 10), and a cell housing (150) accommodating the electrode stack (6), - the first current conductors (8) being closed a common cathode (62) and the second current conductors (10) are joined to form a common anode (64) without melting, - the cell housing (150) having two circumferentially joined housing halves (104), from which the cathode (62) and the anode (64) protrude at least partially, - wherein the housing halves (104) in the areas of the cathode (62) and the anode (64) each have a Vor sealing tape (106, 108) which is joined to the cathode (62) or anode (64) in a materially bonded manner.

Images