DE102023111870A1 - ELECTROCHEMICAL STORAGE CELL WITH A COMPRESSION DEVICE FOR COMPENSATING AN EXPANSION OF STACKED BATTERY CELLS IN THE STACKING DIRECTION - Google Patents

Abstract

An electrochemical storage cell comprises a compression device (60) for compensating an expansion of an electrode stack (30) in the stacking direction. The storage cell comprises the electrode stack (30) arranged in a housing (10) and the compression device (60). The compression device (60) is designed to exert a compression pressure on the electrode stack (30) by means of a rotational movement about the stacking direction. The compression pressure is adjustable depending on a rotational position. The electrode stack (30) is essentially decoupled from the rotational movement of the compression device (60).

Description

The following description relates to an electrochemical storage cell with a compression device for compensating an expansion of stacked electrochemical storage cells in the stacking direction. Furthermore, a storage cell module with electrochemical storage cells is described.

State of the art

Solid-state batteries are a special type of accumulator in which the electrodes and electrolyte are made of solid material. Solid-state batteries are increasingly seen as an important building block for the electrification of mobility. They are considered safer and enable greater range and shorter charging times than conventional lithium-ion batteries.

A known problem with solid-state batteries and other designs concerns variable layer thicknesses. For example, in anode-free all-solid-state batteries (ASSB), there is initially no anode on the anode side in the discharged state, but only a current collector (for example a copper foil). In the charged state, an anode in the form of pure lithium is formed, which migrates from the cathode (lithium is stored in the cathode) through a separator during the charging process and is deposited or formed on the copper foil. In order to put the cell into operation, the electrode layers must be pressed together. The necessary forces are in the kN range or the pressures in the double-digit bar range).

The state of the art offers solutions to these problems. However, it remains a technical challenge to keep the compression forces or pressures, once set, within certain limits, especially in electrode stacks with variable height. For example, if the forces in the cell are designed for a charged state, the corresponding forces in the intermediate states between the charged and discharged states would be too low. The cell could not function properly. If the forces in the cell are designed for the discharged state, the compression forces or pressures in the intermediate states between the charged and discharged states would be too high. The cell could burst.

Constant pressing of the layers of an electrode stack can be achieved by active or passive pneumatic or hydraulic systems. However, this means, for example, that either all cells must be supplied with one pressure unit or corresponding modules with several cells must each be supplied with one pressure unit. This is complex and requires a lot of space, for example to be able to compensate for the expansion of individual cells or several cells in the module. A hydraulic system must be continuously supplied with energy in order to keep the pressing forces constant even during longer periods of downtime. Hydraulic systems can be prone to leaks and a piping system also requires space.

One object is to specify an electrochemical storage cell that can be operated with a compression pressure that is easier to adjust and maintain. Furthermore, a storage cell module made of such electrochemical storage cells is to be specified.

This object is achieved by an electrochemical storage cell and a storage cell module according to the independent and subordinate claims. Advantageous embodiments and further developments emerge from the dependent claims.

Summary

It is understood that any feature described with respect to any embodiment may be used alone or in combination with other features described herein, and may be used in combination with one or more features of any other embodiment, or in any combination of any other embodiment, unless explicitly described as an alternative. Furthermore, equivalents and modifications not described below may be used without departing from the scope of the claimed subject matter.

An electrochemical storage cell refers below to an energy storage device based on electrochemicals, in particular a rechargeable energy storage device that is suitable for storing electrical energy and delivering it to a consumer, for example a consumer in a vehicle. An electrochemical solid-state cell is a solid-state battery, such as a lithium-ion battery, so that the following description also refers to a lithium-ion solid-state battery. A solid is understood to be a chemical substance that is rigid at the temperatures usually prevailing in an electrochemical storage cell or at least has a very low tendency to flow, as can be the case with polymers, for example.

In the following, the term "lithium ion battery" is used synonymously for all terms commonly used in the state of the art for galvanic elements and electrochemical storage cells containing lithium, such as lithium battery, lithium cell, lithium ion cell, lithium polymer cell, lithium ion battery cell and lithium ion accumulator. In particular, rechargeable batteries, so-called secondary batteries, are included. The terms "battery" and "electrochemical storage cell" are also used synonymously with the terms "lithium ion battery" and "lithium ion cell".

The term "electrode stack" refers to a sequence of layers or films. In an electrochemical storage cell, the layers follow one another. However, this does not mean that the layers specified here have to follow one another directly. Rather, intermediate layers can also be provided, such as a separator, insulator, electrode binder, coatings and electrical conductivity additives, which can be applied to an electrically conductive carrier of the respective electrodes.

An electrochemical storage cell typically has various electrodes, a positive electrode (cathode) and a negative electrode (anode), which can be electrically contacted via current collectors. Each of these electrodes has at least one active material, optionally together with additives such as electrode binders and electrical conductivity additives, which is applied to an electrically conductive carrier (for example a metal foil) or to a current collector of the respective electrodes. Non-porous and solid conductor foils made of aluminum (for the positive electrode) or copper (for the negative electrode) are typically used as the electrically conductive carrier. Such conductor foils are typically impermeable to liquid electrolyte and gases. The electrochemical storage cells described below can be used with a liquid electrolyte or can be designed with a solid electrolyte as electrochemical solid storage cells, for example as a ceramic or polymer-based solid battery. An electrochemical solid cell comprises a solid electrolyte.

Furthermore, an electrochemical storage cell with a compression device for compensating an expansion of an electrode stack in the stacking direction is proposed.

According to one embodiment of the invention, the electrochemical storage cell comprises the electrode stack arranged in a housing and the compression device. The compression device is designed to exert a compression pressure on the electrode stack by means of a rotational movement about the stack direction. The compression pressure is adjustable depending on a rotational position. The electrode stack is essentially decoupled from the rotational movement of the compression device. The electrode stack is essentially stationary regardless of the rotational position of the compression device.

The electrochemical storage cell can be arranged in a round housing (as a round cell). The housing is, for example, cylindrical and has a circular cross-section. The other components, in particular the electrode stack, in the housing can preferably also have a circular cross-section. The electrode stack can be mixed with a liquid electrolyte or the electrode stack can be provided with a solid electrolyte that is embossed into the layer sequence of the electrode stack. In this way, an electrochemical solid storage cell (abbreviated to ASSB or all-solid-state battery) can be formed.

When the electrochemical storage cell is in operation, a compression pressure can be set on the electrode stack. This is done by a rotary movement on the compression device. By decoupling the compression device from the electrode stack, the rotary movement does not act directly on the electrode stack. The compression pressure can act on the electrode stack in the stacking direction. The rotary movement is converted into a translational movement by the compression device. This has the effect that the electrode stack does not rotate with the compression device. In this way, there are no shear forces that could damage or destroy the electrode stack. The compression device thus allows the compression pressure to be easily adjusted. Furthermore, the compression pressure can be maintained essentially without energy and easily.

The invention is based in particular on the considerations set out below. One aspect aims to ensure that the electrodes of an electrode stack are pressed as consistently as possible in the different charge states. One solution relates to a compression device that can compensate for an expansion of stacked electrodes of the electrochemical storage cell in the stacking direction, for example by being able to continuously adjust a change in the layer height without energy being required in a certain charge state of the storage cell to maintain this state. Energy can be used if the layer thickness must be readjusted in order to keep compression forces within certain threshold values. Basically, the electrochemical storage cell can be constructed like a screw. When the screw is tightened, pressure is generated; when the screw is unscrewed, the pressure is released. The screw can also be readjusted as required. This can be determined in advance in a laboratory.

The proposed electrochemical storage cell can be compared to a "lipstick", where the bottom can be driven by an actuator that drives a cell or a row of cells or even a module. Depending on the direction of movement of the actuator, the electrodes are "pressed" or "relieved" ("pressed": the cell discharges, "relieved": the cell is charged, for example, the anode layers are formed depending on the state of charge). In order to prevent the electrodes from rotating and potentially destroying the layers of the electrode stack, the electrode stack is decoupled via the compression device, so that the electrodes can only be compressed, but essentially no torsion is exerted on the electrode stack by the rotational movement of the compression device.

According to one embodiment, the compression device comprises a threaded adapter that is mechanically connected to the housing. A screw element is designed to adjust the rotational position of the compression device, wherein the screw element can be screwed to the threaded adapter. The compression device further comprises an axial needle roller bearing arranged between the electrode stack and the screw element, which is designed to decouple the rotational movement about the stack direction from the electrode stack.

The screw element can be screwed in or out of the threaded adapter, increasing or decreasing the compression pressure. The screw nature of the screw element allows the compression pressure to remain at a set value without additional energy being required. The axial needle roller bearing is rotated by the screw element, but does not transfer the rotational movement to the electrode stack, from which it is decoupled. In this way, a propulsion is created which is mediated by the rotational position of the screw element and which exerts the compression pressure on the electrode stack as a translational movement along the stack direction.

According to one embodiment, the screw element has an external thread that can engage an internal thread of the thread adapter so that the screw element can be rotated in the thread adapter. The screw element can be screwed in and out of the thread adapter using the threads.

According to one embodiment, the storage cell comprises a pressure plate. The pressure plate is movable along the stacking direction in the housing and rests, for example, on the axial needle roller bearing. The pressure plate is in mechanical operative contact with an underside of the electrode stack and is designed to exert the compression pressure on the underside of the electrode stack. The pressure plate is moved along the stacking direction by the mechanical operative contact and thus rests, for example, flatly on the underside of the electrode stack. The pressure plate thus acts as a stamp that exerts the compression pressure on the electrode stack.

According to one embodiment, the axial needle roller and cage bearing has a roller needle cage and roller needles that can roll freely in the rolling areas of the roller needle cage. The roller needle cage is dimensionally stable under compression pressure. The axial needle bearing provides a very rigid bearing with a small to very small axial space requirement. Particularly space-saving bearings are achieved when, as here, the pressure plate can be used as a raceway for the roller needles.

According to one embodiment, the storage cell comprises a further pressure plate. The further pressure plate is arranged mechanically fixed in the housing, so that the further pressure plate is in mechanical operative contact with an upper side of the electrode stack and is designed to exert a counterpressure to the compression pressure on the upper side of the electrode stack. The electrode stack can thus be pressed between the two pressure plates in accordance with the compression pressure set in the housing by the screw element.

According to one embodiment, the electrode stack comprises a stack arrangement of successive layers. In a charged state, the stack arrangement comprises at least one cathode layer, at least one anode layer and at least one separator layer arranged between the cathode layer and the anode layer. The anode layer can be completely or partially degraded in a discharged state.

According to one embodiment, the successive layers of the electrode stack are stacked in the stacking direction on an inner tube arranged in the housing. The at least one cathode layer and at least one anode layer are electrically contacted with the housing or the inner tube.

According to one embodiment, the electrochemical storage cell is designed as a solid storage cell and in particular comprises a solid electrolyte. In a further embodiment, the electrochemical storage cell comprises a liquid electrolyte or an electrolyte that is liquid under compression pressure and gaseous under standard conditions.

According to one embodiment, the screw element has a lateral adjusting thread for engaging an external actuator. The lateral adjusting thread enables the external actuator, for example a motor or stepper motor, to adjust and/or change the compression pressure. The lateral adjusting thread can be implemented as an external thread of the screw element or combined with it.

Furthermore, a storage cell module is proposed. According to one embodiment, the storage cell module comprises a plurality of electrochemical storage cells according to one of the preceding claims. The module also comprises at least one external actuator that is designed to drive the compression device in order to exert a compression pressure on the electrode stack and to adjust the compression pressure depending on a rotational position. The external actuator(s) can be operated by a control unit that adjusts the compression pressure on the electrode stack. For example, the control unit can measure a charge state of one or more of the electrochemical storage cells or receive corresponding measurement signals. The control of the external actuator(s), and thus the control of the corresponding compression pressure, can thus take place depending on the charge states of electrochemical storage cells of the storage cell module. For example, individual cells, cell rows or modules can be driven/controlled individually, for example by the drive belts on the external actuator or a main drive source being engaged or not engaged. For this purpose, a toothed belt can be alternately tensioned and drive the compression device or not tensioned and not drive the compression device.

In the following, embodiments of the invention are described with reference to the accompanying drawings. This provides further details, preferred embodiments and further developments. Identical or identically acting components are provided with the same reference numerals in the figures. The components shown and the size relationships of the components to one another are not to be regarded as being to scale. Insofar as components and parts in the various figures are identical in their function, their description is not necessarily repeated for each of the following figures.

Short description of the drawings

• 1A bis 1D ein Ausführungsbeispiel einer elektrochemischen Speicherzelle,
• 2A, 2B ein Ausführungsbeispiel einer elektrochemischen Speicherzelle in geladenem und entladenem Zustand in Schnittdarstellung,
• 3A, 3B das Ausführungsbeispiel einer elektrochemischen Speicherzelle in geladenem und entladenem Zustand in Außenansicht,
• 4A, 4B ein Ausführungsbeispiel einer Kompressionsvorrichtung mit externem Stellantrieb,
• 5A, 5B ein weiteres Ausführungsbeispiel einer elektrochemischen Speicherzelle, und
• 6A, 6B das Ausführungsbeispiel einer elektrochemischen Speicherzelle in geladenem und entladenem Zustand in Vergrößerung.

In detail:

• 1A to 1D an embodiment of an electrochemical storage cell,
• 2A , 2B an embodiment of an electrochemical storage cell in charged and discharged state in sectional view,
• 3A , 3B the embodiment of an electrochemical storage cell in charged and discharged state in external view,
• 4A , 4B an embodiment of a compression device with external actuator,
• 5A , 5B another embodiment of an electrochemical storage cell, and
• 6A , 6B the embodiment of an electrochemical storage cell in charged and discharged state in enlargement.

Detailed description

The 1A to 1D show an embodiment of an electrochemical storage cell. The figures show an exploded view of the electrochemical storage cell, whereby the representation is 1A and 1B and the electrochemical storage cell is shown in the combination of both figures, as shown in 1C is shown.

1A shows a housing 10, a first pressure plate 20 and an electrode stack 30. The housing 10 is designed in this example as a round housing or cylinder and is made of metal or another pressure-resistant material, for example. Alternatively, the electrochemical storage cell can also be designed as a prismatic cell, whereby the housing is also made of a solid material, usually metal. The housing can have a polygonal cross-section, such as a hexagonal cross-section. The storage cell designed as a round cell, for example, is a storage cell that can be produced cost-effectively and quickly. The round cell enables a surface contact between contacting elements and the respective electrode, which is electrically connected to the respective contacting element. Various other components of the electrochemical Storage cell is presented. Unless explicitly stated, these components have at least a similar cross-section to the housing, so that the components can be connected to the housing or designed to be movable within it. In the case of a round housing or a round cell, the cross-section is essentially circular.

In 1A the housing 10 is shown in an external view. The housing delimits an internal receiving space 11 (not shown) with a circular cross-section, in which an electrode stack 30 can be received. The housing comprises a housing shell 12 and a cover 13. The receiving space is delimited by the cover on a first side S1 in the longitudinal direction of the cylindrical housing. The housing shell and the cover are made from one piece in this example. Alternatively, the cover can be screwed to the housing shell or otherwise mechanically connected (for example welded or crimped). The cover also comprises a central cover opening 14, which allows access to the interior of the electrochemical storage cell, for example to insert an inner tube. Furthermore, the cover opening can be used to fill in an electrolyte and/or coolant.

A first pressure plate 20 is designed according to the cross-section of the housing, in this example essentially circular. The pressure plate comprises a pressure plate base 21 and a pressure plate edge 22. The pressure plate base is designed to rest in a form-fitting manner on an upper side S2 of the electrode stack 30. The pressure plate edge comprises a wall that extends in a plate shape along the circumference of the pressure plate and rises from the pressure plate base. Furthermore, the pressure plate has a central pressure plate opening 23 that essentially coincides with the cover opening 14 and is coaxial with it. In this example, the pressure plate opening is structured into a pressure plate elevation 24 that can engage in a form-fitting manner in the pressure plate opening. The pressure plate opening is large enough to accommodate an inner tube 40 or for the inner tube to be passed through the pressure plate opening. For insulation between the inner ear 40 and the housing shell 12, an insulation ring 25 is provided, which can be crimped as a plastic part to the elevation 24 with the pressure plate opening or can be mechanically connected in another suitable way.

The first pressure plate 20 is inserted into the housing and permanently connected to the housing shell 12, for example welded, crimped or screwed. "Permanently connected" here means that the connection is strong enough to withstand at least the compression pressure with which the electrode stack 30 is pressed. Alternatively, or in addition, the pressure plate can be supported by an edge or collar on the cover 13 in order to have a defined dimension. Due to the plate shape of the pressure plate or the pressure plate edge 22, an upper internal cavity is formed between the cover 13 and the pressure plate base 21 on the first side S1.

The electrode stack 30 comprises a plurality of stacks arranged one on top of the other, wherein the respective stack has layers arranged one on top of the other, namely at least one cathode layer 31, at least one anode layer 32 and at least one separator layer 33 arranged between the cathode layer and the anode layer. Furthermore, the stacks can have further layers such as insulators and metallic conductor foils (for example made of aluminum or copper). The cathode layers and the anode layers are electrically contacted with the inner tube 40 or with the housing casing 12 via corresponding tabs 34.

The top side S2 of the electrode stack 30 engages the first pressure plate 20 in a form-fitting manner. The pressure plate base 21, for example, lies essentially over its entire surface on the top side S2 of the electrode stack. Since the first pressure plate 20 is mechanically firmly connected to the housing 10 or the housing casing 12, the pressure plate cannot move under pressure.

1B shows the inner tube 40, a second pressure plate 50 and a compression device 60. The inner tube 40 is formed separately from the electrode stack 30 and is guided through a stack opening 35 through the electrode stack, so that the inner tube is surrounded by the electrode stack in a length region 41. The inner tube is guided through the electrode stack to such an extent that it engages with a stamp-shaped upper side 42 in the cover opening 14 of the cover 13. A lower side 43 of the inner tube is connected to a central opening 53 of the second pressure plate 50 via an O-ring 44 and is sealed by the inner tube. The inner tube is arranged along a stacking direction of the electrode stack.

A second pressure plate 50 is designed according to the cross-section of the housing 20, in this example essentially circular. The pressure plate comprises a pressure plate base 51 and a pressure plate edge 52. The pressure plate base is designed to rest on an upper side of the compression device 60. The pressure plate edge comprises a seal which extends along the circumference of the pressure plate and seals the pressure plate 50 from the housing shell 12, which However, the pressure plate is held within the housing so that it can move in the stacking direction. Furthermore, the pressure plate has a central pressure plate opening 53 which essentially coincides axially with the cover opening 14, so that the inner tube 40 can be guided into the central pressure plate opening 53 and ends in this area.

The pressure plate opening is large enough to accommodate the inner tube 40 or the inner tube can be passed through the pressure plate opening. The second pressure plate 50 is introduced into the housing and is movable along the housing shell 12 and the inner tube 40.

The compression device 60 is made up of several parts and in this embodiment comprises an axial needle roller bearing 61, a threaded adapter 62 and a screw element 63. The axial needle roller bearing 61 comprises a roller needle cage 64 and roller needles 65. Needle roller bearings are roller bearings with a particularly low design. The roller needles are rolling elements that can be conical or cylindrical. The needle roller's needle-shaped profile is created by a tumbled or slightly ground end face in combination with an elongated outer surface. Conical roller needles are advantageous because more needles can be used in comparison. More needles contribute to better load distribution. The roller needle cage 64 and the roller needles 65 each comprise a central bearing opening 71 and can be made of plastic, metal or a combination of both. The rolling needles 65 are located in rolling areas 66 of the rolling needle cage 64 and can thus roll freely on the underside of the pressure plate base 51. The rolling needle cage is essentially circular and can be inserted into the threaded adapter 62 and thus rest on the screw element 63. In this way, the screw element and the second pressure plate serve as surfaces on which the rolling needles can roll.

When the electrochemical storage cell is assembled, the circular threaded adapter 62 is mechanically stably connected to the housing 10, for example welded or crimped to the housing shell 12. In this way, the threaded adapter is firmly connected to the housing. The threaded adapter has an internal thread. The circular screw element 63 has an external thread 68 that can engage in the internal thread of the threaded adapter 62. The external thread is, for example, a screw thread (for example, helicoidal). The thread enables the screw element to be rotated or screwed in the threaded adapter. The screw element also has a rotating surface 67 with a central rotating surface opening 70. When assembled, the axial needle bearing 61 rests on the rotating surface so that the roller needles 65 can rotate freely in the roller needle cage 64.

The screw element 63 also has a lateral adjusting thread 69. An external actuator 80 can engage in the lateral adjusting thread and thus rotate the screw element 63. The adjusting thread can be a separate thread from the external thread 68 and can be arranged, for example, in a lateral area of the screw element in which the external thread is not located. Alternatively, as in 1B As indicated, a combination thread can comprise the external thread 68 and the lateral adjusting thread 69. For this purpose, for example, the external thread is interrupted by notches along the circumference of the screw element 63 so that a threaded rod of the external actuator 70 can engage in the notches and thus rotate the screw element in the thread adapter.

The 1C and 1D show the electrochemical storage cell in its assembled state. The components as shown in the 1A and 1B shown and described above. The inner tube 40 serves as the inner stacking axis, which brings the two pressure plates 20, 50, the electrode stack 30 and the compression device 60 together and stacks them on top of each other. The inner tube 40 is guided through the rotating surface opening 70, the bearing opening 71, the pressure plate opening 53, the stacking opening 35 and the pressure plate opening 23, which are arranged coaxially along the inner tube.

When assembled in this way, compression pressure can be exerted on the electrode stack 30 by raising and lowering the pressure plate 50 - mediated by the compression device 60. To do this, the screw element 63 is turned manually or by the external actuator 80. The external thread 68 then engages in the internal thread of the thread adapter 62 and can be screwed in or out of the thread adapter. The first pressure plate 20 is firmly connected to the housing shell 12 and thus acts as a stop surface (cf. pressure plate base 21) against which the electrode stack is pressed when the compression pressure is built up by the compression device by means of the screw element. The electrode stack is pressed by the corresponding counterpressure.

1C shows an example of a state in which the cell is turned out and 1C shows an example of a state in which the cell is screwed in. Also shown is the external actuator 80, which is indicated as a threaded rod or belt. By screwing in and out a distance between the rotating surface 67 and the second pressure plate 50 or the pressure plate base 51 becomes smaller or larger. The axial needle bearing 61 can rotate freely in the threaded adapter and against the rotating surface 67. The pressure plate 51 can thus be lifted from a rotational movement of the screw element 63, the rotation being translated into a translational movement along the inner tube 40. This is made possible by the roller needles 65, which move in the roller needle cage 64. In this way, it can be ensured that the pressure plate 50 does not transmit any rotational movement caused by the compression device 60 into the electrode stack 30.

The 2A and 2B show an embodiment of an electrochemical storage cell in charged and discharged state in sectional view. This example corresponds to the one in the 1A and 1B shown and described above in the assembled state. In 2A the memory cell is charged and in 2B the memory cell is discharged.

The cell is designed, for example, as a solid-state cell, in particular as an anode-free all-solid-state battery (ASSB). The electrode stack 30 shown in section comprises several stacks arranged on top of one another. A stack has layers arranged on top of one another, namely a cathode layer 31, an anode layer 32 and a separator layer 33 arranged between the cathode layer and the anode layer. Furthermore, the stacks can have further layers such as insulators and metallic conductor foils (for example made of aluminum or copper), which are not shown here. The cathode layers and the anode layers are electrically contacted with the inner tube 40 or with the housing shell 12 via corresponding tabs 34.

In this example, a lithium battery is considered. Here, the cathode layers 31 have essentially the same layer thickness when charged and discharged. In contrast, the layer thickness of the anode layers 32 changes depending on the state of charge. In the charged state, anode layers have been deposited. These are formed by the charging process, with lithium collecting on conductor foils (for example copper foils). The electrode stack grows in height by the thickness of an anode layer x number of layers. In the discharged state, no anode layer 32 is formed. Lithium is stored in the cathode layers. The lithium migrates from the anode layers through the separator layers 33 into the cathode layers and is stored there. The different layer thicknesses are indicated in the drawings (see. 2A : the memory cell is charged and 2B : the storage cell is discharged). In both states, a desired compression pressure is set that acts on the electrode stack 30. This is done by means of the compression device 60.

In 2A the compression device is extended relative to the housing 10. This is visible in the drawing in that the screw element 63 is extended relative to the thread adapter 62, which is fixed to the housing 10. The pressure plate 50 rests on the underside of the electrode stack and thus imparts the compression pressure to the electrode stack. In 2B the compression device is retracted relative to the housing 10. This is visible in the drawing in that the screw element 63 is retracted relative to the threaded adapter 62, which is fixed to the housing 10, i.e. it protrudes further into the housing 10. This can also be seen in that the inner tube 40 protrudes further into the screw element. The pressure plate 50 thus continues to impart the compression pressure to the electrode stack. The drawings also indicate the external actuator 80, which causes the screw element to rotate. It should be noted that the position of the external actuator in relation to the housing remains unchanged.

The 3A and 3B show the embodiment of an electrochemical storage cell in charged and discharged state in external view. This example corresponds to the one in the 1A and 1B shown and described above in the assembled state. In 3A the memory cell is charged and in 3B the storage cell is discharged. The drawings show how the screw element 63 is extended and retracted relative to the threaded adapter 62, which is fixed to the housing 10, i.e. how it extends further or less into the housing 10 depending on the charge level. It can also be seen how the position of the external actuator 80 remains unchanged in relation to the housing.

The 4A and 4B show an embodiment of a compression device with external actuator. 4A a view of the cell from below. Visible is the underside of the screw element 63. 4A a view of the cell from above. Visible is the top of the cover 13.

The external actuator 80 is double-sided in this example and comprises, for example, two threaded rods or belts. The external actuator engages in the external thread 68 or the lateral adjusting thread 69 of the screw element 63. By moving the threaded rods or belts, a rotary movement of the screw element is achieved. screw element 63 causes the pressure plate 50 to move up and down along the inner tube 40 as described above and ultimately adjusts the compression pressure on the electrode stack 30. Typically, several electrochemical storage cells are combined to form a battery module. In principle, each electrochemical storage cell can have its own actuator. In a battery module, an actuator can operate several electrochemical storage cells. For example, several electrochemical storage cells can be arranged in a row so that a common threaded rod or a common belt engages in the corresponding external threads 68 or lateral adjusting threads 69 of the screw elements 63 of the electrochemical storage cells.

The 5A and 5B show another embodiment of an electrochemical storage cell. This example is a further development of the embodiment shown in the 1A to 1D is shown. In contrast, the screw element 63 of the electrochemical storage cell is designed inside the housing 10. The external thread 68 or the lateral adjusting thread 69 of the screw element is accessible through a lateral housing opening 15. The external actuator thus engages in the external thread 68 or the lateral adjusting thread 69 via the lateral housing opening. The thread adapter is thus a part of the housing, for example an internal thread of the housing. An advantage of this embodiment is that the cell can have the same height during operation and can rest on the underside so that the height change takes place within the cell housing. The cell is the same for the environment and does not vary in height.

The 6A and 6B show the embodiment of an electrochemical storage cell in charged ( 6A) and discharged state ( 6B) in magnification. This example corresponds to the one in the 1A and 1B shown example and the embodiment described above in the assembled state. It can be clearly seen that in the charged state, anode layers 32 are formed, which recede in the discharged state or, as indicated in the drawing, are no longer present. The resulting difference in the layer thicknesses leads to the compression pressure being adjusted. This is done by the external actuator 80 by turning the screw element 63 within the thread adapter 62 or an internal thread of the housing 10.

Although the invention has been illustrated and described in detail using embodiments, the invention is not limited by the embodiments. Rather, other variations of the invention can be derived therefrom by a person skilled in the art without departing from the scope of the invention as defined by the claims.

list of reference symbols

10

Housing

11

recording room

12

housing shell

13

Lid

14

lid opening

15

housing opening

20

printing plate

21

printing plate base

22

printing plate edge

23

printing plate opening

24

printing plate elevation

25

insulation ring

30

electrode stack

31

cathode layer

32

anode layer

33

separator layer

34

tabs

35

stack opening

40

inner tube

41

length range

42

stamp-shaped top

43

bottom

44

O-ring

50

printing plate

51

printing plate base

52

printing plate edge

53

printing plate opening

60

compression device

61

axial needle roller and cage bearings

62

thread adapter

63

screw element

64

roller needle cage

65

rolling pins

66

rolling area

67

turning surface

68

external thread

69

lateral adjusting thread

70

rotating surface opening

71

storage openings

80

external actuator

S1

Page

S2

Page

Claims (10)

An electrochemical storage cell with a compression device (60) for compensating an expansion of an electrode stack (30) in the stacking direction, comprising the electrode stack (30) arranged in a housing (10) and the compression device (60), wherein: - the compression device (60) is configured to exert a compression pressure on the electrode stack (30) by means of a rotational movement about the stacking direction and the compression pressure is adjustable depending on a rotational position, and - the electrode stack (30) is substantially decoupled from the rotational movement of the compression device (60). The memory cell after claim 1 , wherein the compression device (60) comprises: - a threaded adapter (62) mechanically connected to the housing (10), - a screw element (63) for adjusting the rotational position of the compression device (60), wherein the screw element (63) can be screwed to the threaded adapter (62), and - an axial needle roller bearing (61) arranged between the electrode stack (30) and the screw element (63), which is designed to decouple the rotational movement about the stacking direction from the electrode stack (30). The memory cell after claim 2 , wherein the screw element (63) further has an external thread (68) which can engage with an internal thread of the thread adapter (62) so that the screw element (63) is rotatable in the thread adapter (62). The memory cell after claim 2 or 3 , further comprising a pressure plate (50), wherein the pressure plate (50): - is movable along the stacking direction in the housing (10) - rests on the axial needle bearing (61), - is in mechanical operative contact with an underside of the electrode stack (30) and - is configured to exert the compression pressure on the underside of the electrode stack (30). The memory cell after claim 3 or 4 , wherein the axial needle roller bearing (61) has a roller needle cage (64) and roller needles (65) which can roll freely in rolling areas (66) of the roller needle cage (64). The storage cell according to one of the preceding claims, comprising a further pressure plate (20), wherein the further pressure plate (20) - is arranged mechanically fixed in the housing (10) so that the further pressure plate (20) is in mechanical operative contact with an upper side of the electrode stack (30) and - is configured to exert a counterpressure to the compression pressure on the upper side of the electrode stack (30). The memory cell according to one of the preceding claims, wherein - the electrode stack (30) comprises a stack arrangement of successive layers, and - the stack arrangement in a charged state comprises at least one cathode layer (31), at least one anode layer (32) and at least one separator layer (33) arranged between the cathode layer and the anode layer. The memory cell after claim 7 , wherein - the successive layers of the electrode stack (30) are stacked in the stacking direction on an inner tube (40) arranged in the housing, and - the at least one cathode layer (31) and at least one anode layer (32) are electrically contacted with the housing or the inner tube (40). The storage cell according to one of the preceding claims, wherein the screw element (63) has a lateral adjusting thread (69) for engaging an external actuator (80). A storage cell module with a plurality of electrochemical storage cells according to one of the preceding claims and at least one external actuator (80) which is configured to drive the compression device (60) in order to exert a compression pressure on the electrode stack (30) and to adjust the compression pressure as a function of a rotational position.