Electrochemical storage cell and method for setting compression pressure of electrochemical storage cell

Abstract

The invention relates to an electrochemical storage cell, comprising a housing (20), which comprises a housing jacket (21), a housing lower side and a housing upper side. An electrode stack (40) is arranged between a housing lower side and a housing upper side in an interior of the housing (20) delimited by the housing jacket (21). The bellows (10) is connected to the housing jacket (21) on the lower side of the housing and is designed to exert a compression pressure on the electrode stack (40) by means of elastic deformation.

Description

TECHNICAL FIELD

[0001] The following description relates to an electrochemical storage cell with an elastically loaded compression device for compensating for the expansion of a stack of electrochemical storage cells in the stacking direction. Furthermore, a method for setting the compression pressure of an electrochemical storage cell is described. BACKGROUND

[0002] Solid-state batteries are a particular type of accumulators in which electrodes and electrolytes are made of solid materials. Solid-state batteries are increasingly being viewed as an important cornerstone for driving the electrification of transportation. They are considered to be safer and enable longer ranges and shorter charging times compared to conventional lithium-ion accumulators. In addition, lithium-silicon batteries are increasingly being developed in which silicon-based anodes are used and lithium ions are used as charge carriers.

[0003] A problem known in the battery technology of storage cells such as solid-state batteries and lithium-silicon batteries relates to varying layer thicknesses. In anode-free solid-state batteries (anode-free all-solid state batteries, ASSB), for example, in the discharged state there is first no anode constructed on the anode side, but only a current collector (for example a copper foil) is present. In the charged state, an anode in the form of pure lithium is constructed, which lithium migrates from the cathode (in which lithium is stored) through the separator during the charging process and deposits or is constructed on the copper foil. In order for the cell to function, the electrode layers have to be pressed together. The forces required are in the range of kilo Newton (kN) or the pressure is in the range of two-digit bar.

[0004] The prior art provides solutions for these problems. However, it is still a technical challenge to keep a compression force or compression pressure, which is set once, within certain limits, especially in the case of a varying height of the electrode stack. When the force in the cell is designed for the charged state, for example, the corresponding force in the intermediate state between the charged state and the discharged state is too small. The cell can not function correctly. When the force in the cell is designed for the discharged state, the compression force or compression pressure in the intermediate state between the charged state and the discharged state is too high. The cell can burst.

[0005] A constant compression of the layers of the electrode stack can be realized pneumatically or hydraulically. However, this results in the fact that either all monoblocs have to be provided with a pressure unit or the corresponding modules with multiple monoblocs have to be provided with a pumping or pressure unit, respectively. This is costly and requires a lot of space in order to be able to compensate for the expansion of the individual monoblocs or multiple monoblocs in the module, for example. The hydraulic or pneumatic system has to be continuously provided with energy in order to constantly maintain the compression pressure also in the case of longer downtimes. These systems can be prone to leaks, the piping system has to be provided with oil and takes up valuable installation space. SUMMARY

[0006] It is the task to design an electrochemical storage monobloc which can be operated with a compression pressure which can be set and maintained more easily. Furthermore, a method for setting a compression pressure of an electrochemical storage monobloc should be given.

[0007] The task is solved by an electrochemical storage monobloc and a storage monobloc module according to the independent claims and the claims dependent thereon. Advantageous embodiments and improvements result from the dependent claims.

[0008] It is based hereinafter that each feature described with respect to any embodiment can be used individually or in combination with other features described herein; and can be used in combination with one or more features of any other embodiment, or in any combination with any other embodiment, unless explicitly described as an alternative. Furthermore, equivalent solutions and modifications not described hereinafter can be used, without departing from the scope of application of the claimed subject matter.

[0009] An electrochemical storage monobloc means hereinafter an electrochemical accumulator, in particular a rechargeable accumulator, which is suitable for storing electrical energy and outputting the electrical energy to a consumer, for example in a vehicle. The electrochemical solid-state monobloc is a solid-state battery, for example a lithium-ion battery, so that the following description also relates to a lithium-ion solid-state battery. Solid-state is to be understood as a chemical substance which is rigid or at least has a very small tendency to flow at the temperatures prevailing in an electrochemical storage monobloc, as this can be the case for example in polymers.

[0010] The term "lithium-ion battery" is used synonymously hereinafter for all common names for lithium-containing primary cells and electrochemical storage monoblocs (short: monoblocs) in the prior art, for example lithium battery, lithium monobloc, lithium-ion monobloc, lithium polymer monobloc, lithium-ion battery monobloc and lithium-ion accumulator. In particular, rechargeable batteries, so-called secondary batteries, are included. The terms "battery" and "electrochemical storage monobloc" are also used synonymously with the terms "lithium-ion battery" and "lithium-ion monobloc".

[0011] The term "electrode stack" denotes a sequence of layers or foils. In electrochemical storage cells, these layers follow one another. This does not mean, however, that the layers given here must directly follow one another. Rather, it is also possible to provide intermediate layers, such as separators, insulators, electrode binders, coatings and conductive additives, which can be applied to the conductive carrier of the respective electrode.

[0012] Electrochemical storage cells typically have different electrodes (positive electrode (cathode) and negative electrode (anode)), which can be connected via current collector electrical contacts. Each of these electrodes has at least one active material, optionally together with additives such as electrode binders and conductive additives, which are applied to a conductive carrier (e.g. a metal foil) or to the current collector of the respective electrode. As conductive carrier, typically non-porous and robust conductor foils made of aluminum (for positive electrodes) or copper (for negative electrodes) are used. Such conductor foils are typically impermeable to liquid electrolytes and gases. The electrochemical storage cells described below can be used with liquid electrolytes or designed as electrochemical solid-state storage cells, e.g. as ceramic or polymer-based solid-state batteries, in combination with solid-state electrolytes. Electrochemical solid-state cells comprise a solid-state electrolyte.

[0013] Furthermore, an electrochemical storage cell is proposed, which is designed to compensate for a change in compression pressure due to an expansion of the electrode stack in the stacking direction.

[0014] According to an implementation form, the electrochemical storage cell comprises a housing. The housing further comprises a housing outer cover together with a housing lower side and a housing upper side. An electrode stack is arranged in an interior space of the housing, which is delimited by the housing outer cover, between the housing lower side and the housing upper side. A bellows is provided and the bellows is connected to the housing outer cover at the housing lower side. The bellows is designed to exert a compression pressure onto the electrode stack by elastic deformation.

[0015] The housing of the electrochemical storage cell can be embodied as a round housing (as a round cell). The housing is, for example, cylindrical and has a round cross section. Other components in the housing, in particular the electrode stack, can preferably also have a round cross section. The electrode stack can be filled with a liquid electrolyte. Alternatively, the electrode stack can be provided with a solid-state electrolyte, which is imprinted into the layer sequence of the electrode stack. In this way, an electrochemical solid-state storage cell (in short: ASSB or All-Solid-State-Battery) can be shaped.

[0016] A bellows, also called wave tube, has a housing with a wave-shaped transformed diameter. The housing is made of metal, for example, so that the bellows is also embodied as a metal bellows or metal wave tube. In one embodiment, the housing is embodied as a round monolith. The bellows has a round cross section and encloses a cylindrical housing volume at the housing underside. The housing volume comprises an interior space of the housing in which the electrode stack is arranged.

[0017] The housing and the bellows can have other cross sections and geometries, for example, the housing and the bellows can have a polygonal cross section, for example, a hexagonal cross section. A memory monolith configured as a round monolith, for example, is a cost- and time-advantageously producible memory monolith. The round monolith enables a planar contact connection between the contact connection elements and the respective electrodes, which are electrically connected to the respective contact connection elements. The bellows can be described as an elastic element with a Hooke's constant, which can be elastically deformed on the basis of its material properties and geometry.

[0018] The electrode stack can have different layer thicknesses depending on the charge state of the electrochemical memory monolith. These layer thicknesses can be "packed" or "unpacked" by the elastic action on the stack ( "packed" : monolith discharging, "unpacked" : monolith charging, for example, the anode layer can be configured depending on the charge state). The bellows is designed to compensate for pressure changes in the electrochemical memory monolith following the electrode stack (for example, due to expansion and contraction of the electrode stack as a result of the charging and discharging processes) and to set it to a desired compression pressure.

[0019] The description is based, inter alia, on the considerations set out below. One aspect relates to an electrochemical memory monolith, which allows a stepless adjustment and compensation of the layer height following the electrode stack without the need for energy. The bellows constitutes a mechanical spring and can be elastically deformed depending on its mechanical properties. In other words, the bellows corresponds to an elastically loaded compression device. By an initial deformation, a compression pressure of a certain size can be set at the electrochemical memory monolith. This takes place, for example, during the assembly or manufacture of the monolith in such a way that the bellows is inserted into the housing under pressure and the bellows waves are thus displaced into a position corresponding to a certain displacement of the "spring" or a desired compression pressure. If the housing is closed in this set state, the compression pressure acts on the electrode stack. Changes in the layer height of the electrode stack can be steplessly readjusted by the elastic action of the bellows without the need for external energy.

[0020] According to one embodiment, the electrochemical storage cell comprises a housing with a housing outer cover and a housing lower side and a housing upper side. An electrode stack is arranged in the interior space of the housing, which is delimited by the housing outer cover, between the housing lower side and the housing upper side. A bellows is connected to the housing outer cover at the housing lower side. Furthermore, the bellows is designed to exert a compression pressure onto the electrode stack by elastic deformation.

[0021] According to one embodiment, the bellows is arranged completely or partially in the interior space of the housing and is movable in the interior space. The bellows is connected to the housing outer cover on the one hand and is movable in the interior space on the other hand. In this way, the bellows can be moved into the housing, for example, or out of the housing. By means of a fixed point at the housing, the bellows can establish a compression pressure relative to the fixing point.

[0022] According to one embodiment, the bellows is crimped, screwed and / or welded to the housing lower side. Alternatively or additionally, a lower housing cover is provided, which encloses the housing.

[0023] According to one embodiment, the bellows has substantially parallel or helical bellows. The bellows is substantially free to move in the stacking direction along the inner wall of the housing.

[0024] According to one embodiment, the electrode stack and the bellows each have a central opening, through which an inner tube is guided for contact connection of the electrode stack. The bellows is movable in the housing in the stacking direction along the inner tube. The inner tube serves for electrical contact connection of the electrode layers of the electrode stack and functions as a central shaft of the cell. Furthermore, the inner tube can assume a safety function and serve for diverting gases. In a thermal event, for example, gases can be diverted purposefully into a safety volume.

[0025] According to one embodiment, the bellows has a pressure surface. The pressure surface is in active contact with the lower side of the electrode stack. The pressure surface is designed to exert a compression pressure onto the lower side of the electrode stack. The pressure surface is moved in the housing, for example, by elastic deformation of the bellows, such that the pressure surface exerts a compression pressure onto the electrode stack in accordance with the displacement of the bellows and compensates for following compression pressure.

[0026] According to one embodiment, the pressure surface and the lower housing cover enclose a safety volume in the region of the bellows. The safety volume is connected to the inner tube for receiving gases from the electrode stack. The safety volume can receive hot gases in a thermal event, for example, and thus moderate the cell.

[0027] According to an embodiment, the pressure plate is movably connected in the housing with a housing cover at the upper side of the housing. The pressure plate rests on the upper side of the electrode stack. Furthermore, the pressure plate is designed to exert a pressure directed against the compression pressure onto the upper side of the electrode stack. The pressure plate acts as a stop surface against which the electrode stack is pressed when the compression pressure is established. The electrode stack is compressed by the corresponding counter pressure.

[0028] According to an embodiment, the pressure plate is designed to break and / or deform in a controlled manner in the event of a thermal event. The pressure plate can be designed with a safety function by selection of shape and / or material. For example, the pressure plate can deform in the event of a thermal event, so that the pressure from the inside of the electrochemical cell causes the plate to bulge. Furthermore, other safety systems can be provided. The pressure plate can have a positive temperature coefficient resistor or PTC resistor or PTC thermistor. For example, the positive temperature coefficient resistor can constitute a ring on or in the pressure plate, which ring becomes an insulator in the event of a temperature increase and cancels the contact connection of the electrochemical cell. In the event of a deformation of the pressure plate, the mechanical connection between the pressure plate and the positive temperature coefficient resistor can be broken and as a result the electrically conductive contact to the electrode stack is interrupted and thus the current flow is interrupted.

[0029] According to an embodiment, a bellows can be replaced by a coil spring. In such an embodiment, the pressure surface can be sealed against the housing cover.

[0030] Furthermore, a method for setting a compression pressure of an electrochemical storage cell is proposed. The method first comprises the step of providing an electrochemical storage cell. The storage cell has a housing with a housing cover, a housing lower side and a housing upper side. Furthermore, an electrode stack is arranged in the interior space of the housing, which is bounded by the housing cover, between the housing lower side and the housing upper side.

[0031] In a further step, the compression pressure is set. This is carried out by means of a bellows, which is connected at the housing lower side with the housing cover. Here, the bellows is elastically deformed by the compression pressure and as a result the compression pressure is exerted onto the electrode stack. Finally, the housing is closed so that the set compression pressure is maintained.

[0032] Embodiments of the application are described below with the aid of the drawings. Further details, preferred embodiments and refinements emerge therefrom. Identical or identically acting components are each provided with the same reference symbols in the figures. The illustrated components and the size relationships of the components to one another are not to be regarded as being true to scale. The description of the components need not be repeated for each of the following figures, as far as the components and components are consistent in their function in the different figures. BRIEF DESCRIPTION OF DRAWINGS

[0033] In detail:

[0034] Figure 1 Examples of electrochemical memory monomers are shown;

[0035] Figure 2A , Figure 2B Examples of electrochemical memory monomers in different charge states are shown;

[0036] Figure 3A , Figure 3B An embodiment of a bellows is shown;

[0037] Figures 4A to 4C Examples of electrochemical memory monomers are shown;

[0038] Figure 5 Another embodiment of an electrochemical memory monomer is shown;

[0039] Figure 6 An example of an electrochemical memory monomer in a single charge state is shown; and

[0040] Figure 7A , Figure 7B Examples of electrochemical memory monomers are shown. Detailed Implementation

[0041] Figure 1 An embodiment of an electrochemical memory cell is shown. The figure shows the electrochemical memory cell in an exploded view. The cell has a bellows 10 and a housing 20 including a contact contact washer 30 and an insulating washer 31. Furthermore, the cell has a pressure plate 32 and an electrode stack 40.

[0042] The housing 20 defines an internal receiving space with a circular cross-section, into which the electrode stack 40 is arranged. The housing includes a housing cover 21 and an upper housing side with an upper housing cover 22. The receiving space is defined at the upper housing side by the housing cover along the longitudinal extension direction of the cylindrical housing. In this example, the housing cover and the housing cover are integrally manufactured. Alternatively, the housing cover may be threaded to the housing cover or otherwise mechanically connected (e.g., welded or crimped). Furthermore, the housing cover includes a central cover opening 23 that allows access to the interior of the electrochemical memory cell, for example, for electrolyte injection and / or as a pressure valve.

[0043] The contact-making washer 30 is inserted into the housing and thus embedded into the housing cover 22. To this end, the contact-making washer is provided with a raised portion 33 which is form-fittingly fitted into the central cover opening 23. The housing can for example constitute the positive (+) or negative (-) electrode of an electrochemical storage cell depending on how the individual cells are constructed and the contact-making. The polarity is for example predefined by the electrode stack 40. The contact-making washer provides the contact-making to the electrode stack and corresponds to the positive or negative electrode. An annular insulating washer 31 can optionally be arranged above or below the contact-making washer and serves to electrically insulate the individual poles of the electrochemical cell from one another. The contact-making washer and the insulating washer can be screwed or otherwise mechanically connected (for example welded or crimped) to the housing 20.

[0044] The pressure plate 32 is designed according to the cross section of the housing 20 and is thus substantially circular in this example. The pressure plate comprises a pressure plate bottom 34 and a pressure plate rim 35. The pressure plate bottom is designed to rest form-fittingly on the upper side 41 of the electrode stack. The pressure plate rim comprises a wall which extends disc-shaped along the circumference of the pressure plate and rises from the pressure plate bottom. In this embodiment, the pressure plate can not have a central opening for example for the inner tube 46. The pressure plate is inserted into the housing 20 and permanently connected to the housing, for example welded, crimped or screwed, at the housing outer cover 21. "Permanently connected" here means that the strength of the connection is sufficient to withstand at least the compression pressure with which the electrode stack can be compressed. The compression pressure can reach values in the range of two-digit kilo Newton (kN). By means of the disc of the pressure plate or by means of the pressure plate rim, an upper inner cavity is formed between the housing cover and the pressure plate bottom. The pressure plate acts as a stop surface against which the electrode stack is pressed when the compression pressure is established. The electrode stack is compressed by the corresponding counter pressure.

[0045] The pressure plate 32 can be equipped with safety functions by selection of shape and / or material. For example, the pressure plate can deform in the event of a thermal event, so that the pressure from the inside of the electrochemical cell causes the pressure plate to bulge. Further safety systems can also be incorporated. The pressure plate can have a positive temperature coefficient resistor or PTC resistor or PTC thermistor. For example, the positive temperature coefficient resistor can constitute a ring on or in the pressure plate which becomes an insulator in the event of a temperature increase and cancels the contact-making of the electrochemical cell or electrode stack 40. In the event of a deformation of the pressure plate, the mechanical connection between the pressure plate and the positive temperature coefficient resistor can be broken and as a result the electrically conductive contact to the electrode stack is interrupted and thus the current flow is interrupted.

[0046] The electrode stack 40 comprises a plurality of stack portions arranged on top of one another, wherein the respective stack portions have electrode layers arranged on top of one another, namely at least one cathode layer 42, at least one anode layer 43 and at least one separator layer 44 arranged between the cathode layer and the anode layer. In addition, the stack portions can have further layers such as insulators and metal conductor foils, for example made of aluminum or copper. The cathode layers and the anode layers are in electrical contact via respective connection plates 45 with an inner tube 46 (not visible) and / or with the housing jacket 21. The upper side of the electrode stack is positively locked to the pressure plate 32. The pressure plate bottom is for example essentially planar on the upper side 41 of the electrode stack. Since the pressure plate is mechanically connected at the housing 20 or the housing jacket, the pressure plate is not movable under pressure. The inner tube 46 (not shown) can be provided as a central shaft and in addition serves for electrical contact of the electrode layers of the electrode stack.

[0047] The bellows 10 is connected at the lower side of the housing with the housing jacket 21. Here, the bellows is screwed or otherwise mechanically connected, for example welded or crimped, on the entire circumference with the housing jacket. The bellows comprises a jacket structured with a plurality of corrugations 11, which delimit an inner cavity 12. The corrugations are structured into the jacket by a wave-shaped change in diameter. The diameter is here chosen such that the bellows can be arranged in the interior of the housing 20 and can move substantially freely in the stacking direction along the inner wall of the housing. The diameter can be chosen such that a desired spring strength of the bellows is achieved. The spring strength of the bellows additionally depends, inter alia, on the material of the bellows and the geometry of the corrugations, which are typically made of metal. In the exemplary embodiment, the bellows encloses a substantially cylindrical cavity. The bellows has a pressure face 13. The pressure face is in mechanical action contact with the lower side of the electrode stack. The lower side of the electrode stack can be designed as a pressure disk. In addition, the pressure face has a central opening 14, for example into which an inner tube is positively locked, which guides through the electrode stack. By means of the inner tube 46, (hot) gas can be guided in the event of a thermal event from the interior of the housing via the bellows into a safety volume (cf. Figure 2A ). In the event of a thermal event, the hot gas can be diverted definedly into the cavity 12 shaped by the bellows and the gas flow is limited. The cavity 12 thus functions as a safety volume. Space is thereby gained and alternative protection means can be reduced or even eliminated.

[0048] The housing 20 and also the bellows 10 can have a polygonal cross section, such as a hexagonal cross section. Storage cells which are configured as round monobodies, for example, are storage cells which can be manufactured cost-effectively and time- effectively. The round monobodies enable a planar contact connection between the contact connection elements, such as the connecting tabs 45, and the respective electrode layers which are electrically connected to the respective contact connection elements. The components of the electrochemical storage cell which are introduced here can have at least a similar cross section to the housing, unless explicitly given, so that the components can be designed to be connectable with the housing or movable in the housing. In the case of a circular housing or a round monobody, the cross section is substantially circular.

[0049] The electrochemical storage cell is assembled by guiding the components as shown in Figure 1 and described above into one another. The inner tube 45 here acts as an internal stacking axis which centrally converges the individual components. After assembly in this way, a compression pressure can be applied to the electrode stack 40 by the elastic action of the bellows 10. To this end, the bellows can be elastically deformed upon assembly. The compression pressure is set by connecting the bellows to the housing 20 or by the housing being closed. The pressure surface 13 of the bellows thereby provides a compression pressure to the electrode stack. Since the bellows 11 are free to move in the stacking direction along the inner wall of the housing, pressure fluctuations which follow, for example, from a change in the layer thickness in the electrode stack, can be compensated for or compensated during operation of the cell. The pressure plate 32, in contrast, is permanently connected to the housing and thus acts as a counter-pressure surface for the compression pressure. The electrode stack is compressed by the respective counter-pressure. The bellows have the function of an elastic element which sets the compression pressure by elastic deformation.

[0050] Figure 2A and Figure 2B An embodiment of an electrochemical storage cell in different states of charge is shown. Unlike Figure 1 , the cell is in an assembled state and is shown as a cross section. The cell is designed as a solid-state battery, in particular as an anode-free solid-state battery (anode-free all-solid-state battery, ASSB), for example. The electrode stack 40 shown in cross section comprises a plurality of stacking sections which are arranged one above another. The stacking sections have layers which are arranged one above another, namely one cathode layer 42, one anode layer and one separator layer arranged between the cathode layer and the anode layer. In addition, the stacking sections can have further layers which are not shown here, such as insulators and metal conductor foils, for example made of aluminum or copper. The cathode layers and the anode layers are electrically in contact with the inner tube or with the housing jacket via the respective connecting tabs.

[0051] In this example a lithium battery is considered. Here the cathode layers 42 have essentially the same layer thickness in the charged, partially discharged and discharged state. In contrast thereto, the layer thickness of the anode layers 43 changes depending on the charge state. In the charged state, anode layers are deposited. These anode layers are built up by the charging process in such a way that lithium collects on the conductor foil, for example a copper foil. The height of the electrode stack increases by the thickness of the anode layers multiplied by the number of layers. In the discharged state, no anode layers are built up. The lithium is stored in the cathode layers. The lithium migrates from the anode layers to the cathode layers through the separator layer and is stored there.

[0052] The different layer thicknesses are illustrated in the figures (reference Figure 2A : memory cell charged, Figure 2B : memory cell discharged). In all illustrated states, a desired compression pressure acting on the electrode stack 40 is set. This is achieved by the bellows 10 by means of the movable pressure surface 13. Due to the described charging and discharging processes, a longitudinal expansion or longitudinal contraction of the electrode stack occurs along the stacking direction. This is illustrated in the cross-sectional views in Figure 2A and Figure 2B . The lower housing cover 24 forms the lower side of the housing and encloses the housing.

[0053] The charged state is illustrated in Figure 2A . Anode layers are built up and the electrode stack has its (in the stacking direction) largest longitudinal expansion dimension in this state. Correspondingly, the bellows is compressed in the housing and a compression pressure is generated depending on the longitudinal expansion dimension of the bellows. The compression pressure is applied to the electrode stack via the pressure surface. Furthermore, an inner tube is illustrated, which can achieve that in the event of a thermal event, the (hot) gas is guided out of the interior of the housing via the bellows in a controlled manner. The possible flow is illustrated in the figures by means of arrows. For this purpose, the pressure surface of the bellows can have a central arch 15, which coincides with the inner tube. In the central arch, a predetermined breaking point 16, a cut or a valve is provided, which breaks, opens or deforms in a controlled manner in the event of a thermal event. In this way, an opening can be formed on the lower side of the housing, through which the gas can flow out. The gas is first guided into the cavity 12 of the bellows 10, which forms a safety volume. In this way, the dangerous gas can be retained in the housing and the thermal event can be mitigated.

[0054] The discharged state is illustrated in Figure 2B . Here, no anode layers 43 are built up any more and the electrode stack 40 has its smallest longitudinal expansion dimension in this state. Correspondingly, the bellows 10 has its largest longitudinal expansion dimension and the compression pressure is generated depending on the longitudinal expansion dimension of the bellows.

[0055] Furthermore, in Figure 2BA possible contact connection is shown in Fig. 5. Here, the negative pole is denoted by (-) and the positive pole by (+). The shown polarity is one example, wherein the negative and positive poles are exchangeable. The cathode layer 42 of the electrode stack 40 is electrically conductively connected via a connecting tab 45 with the housing cover 21. The housing cover and the bellows 10 are placed on the same pole, in this example on the negative pole (-). The upper housing cover 22 is also placed on the same pole, here on the negative pole (-). The housing cover is connected with the housing cover and is likewise on (-). The anode layer 43 of the electrode stack is electrically conductively connected via a connecting tab with the inner tube 46, which is thus placed on the positive pole (+). This is also the case for the pressure plate 32, and a contact connection washer 30 is shown, which is insulated from the housing cover by an insulating washer 31, the contact connection washer thus being placed on the positive pole (+).

[0056] Figure 3A and Figure 3B An embodiment of a bellows is shown. The drawing shows an outer view of a bellows with a helical bellow. The bellow is structured by a wave-shaped transformed diameter at the outer housing cover. Alternatively, the bellow can also be configured in parallel. The bellow gives the bellows an elastic action with a Hooke's constant.

[0057] Figures 4A to 4C An embodiment of an electrochemical storage cell is shown in an outer view. In this example, the bellows 10 extends substantially into the housing 20. In Figure 4B and Figure 4C In the perspective view shown in Fig. 6, the bellows 10 in the above-described charge state can be seen. Here, Figure 4B A cell in the charged state is shown (bellows compressed). The anode layer 43 consists of lithium (lithium from the cathode layer has for example been deposited on the copper conductor foil of the anode layer). Figure 4C A cell in the discharged state is shown (bellows "expanded"). Depending on the cell chemistry, the anode layer weakly consists or does not consist at all, the lithium being stored in the cathode layer 42.

[0058] Figure 5 Another embodiment of an electrochemical storage cell is shown. The example is based on Figure 1 The configuration is similar and differs only in the following changes, which allow an inner tube 46 to be provided substantially over the entire height of the cell.

[0059] In this example, the inner tube 46 is guided from the bellows 10 to the housing cover 22 in the assembled state of the monomer. The inner tube, for example, constitutes the positive (+) electrode of the monomer (or conversely, depending on the configuration of the electrode stack). Furthermore, the pressure plate 32 has a central pressure plate opening 36, which substantially coincides with and can be fitted into the central cover opening 23 in a form-locking manner. The pressure plate opening is large enough to receive the inner tube 46 or for the inner tube to be guided through it. The inner tube is connected to the bellows 10 via an O-ring 18. An insulating portion 17 is provided on the underside of the bellows 10, for example, centrally between the positive (+) and negative (-) electrodes of the monomer. The inner tube 46 is also guided through the electrode stack 40 and is in contact with the electrode layers (anode or cathode layers 42, 43) via a connecting tab 45. An insulating gasket 31 rests against the electrode stack. The inner tube is fitted into the central raised portion 37 of the pressure plate 32 through a central opening in an insulating washer (the insulating washer is annular). The pressure plate is disc-shaped. Furthermore, the inner tube is centrally connected to the housing cover via an O-ring 25 and an insulating ring 26.

[0060] Figure 6 An embodiment of an electrochemical memory monomer in a charge state is shown. The figure shows... Figure 5 A cross-sectional view of the electrochemical memory cell. The inner tube 46 extends from the upper housing cover to the lower housing cover 22, 24 and is guided through corresponding openings in the pressure plate 32, insulating gasket 31, electrode stack 40, and bellows 10. The inner tube is centered by O-rings 18, 25. The reverse polarity is generated by electrical contact between the inner tube and the connecting piece 45 or the electrode layers 42, 43 of the electrode stack. In this example, the positive electrode (+) is located on the inner tube or pressure plate. The negative electrode (-) is located on the housing 20 and the bellows. Figure 7A , Figure 7B From the outside and from above ( Figure 7A ) and from below ( Figure 7B (This shows an assembled electrochemical memory cell.)

[0061] Although the invention has been illustrated and described in detail with reference to embodiments, the invention is not limited to the embodiments described. Instead, other variations of the invention can be derived by those skilled in the art without departing from the scope of protection defined by the claims.

[0062] List of reference numerals

[0063] 10 corrugated pipe

[0064] 11 ripples

[0065] 12. The cavity inside

[0066] 13 pressure surfaces

[0067] 14 central opening

[0068] 15 central arch

[0069] 16 predetermined breaking point, cut or valve

[0070] 17 insulating portion

[0071] 18 O-ring

[0072] 20 housing

[0073] 21 housing cover

[0074] 22 upper housing cover

[0075] 23 central cover opening

[0076] 24 lower housing cover

[0077] 25 O-ring

[0078] 26 insulating ring

[0079] 30 contact-on pad

[0080] 31 insulating pad

[0081] 32 pressure plate

[0082] 33 elevation

[0083] 34 pressure plate bottom

[0084] 35 pressure plate edge

[0085] 36 pressure plate opening

[0086] 37 central elevation

[0087] 40 electrode stack

[0088] 41 upper side

[0089] 42 cathode layer

[0090] 43 anode layer

[0091] 44 separator layer

[0092] 45 connecting tab

[0093] 46 inner tube

Claims

1. Electrochemical storage cell, comprising: - a housing (20) comprising a housing jacket (21) and a housing lower side and a housing upper side; - an electrode stack (40) arranged between the housing lower side and the housing upper side in an interior space of the housing (20) which is delimited by the housing jacket (21); and - a bellows (10) which is connected at the housing lower side with the housing jacket (21) and is designed for exerting a compression pressure onto the electrode stack (40) by elastic deformation.

2. The memory cell of claim 1, wherein, The bellows (10) is arranged completely or partially in the interior space and is movable in the interior space.

3. Memory cell according to one of the preceding claims, wherein The bellows (10) is crimped, screwed and / or welded with the housing lower side and / or a lower housing cover (24) closes the housing (20).

4. Storage cell according to one of the preceding claims, wherein - the bellows (10) has substantially parallel or helical corrugations (11); and - the corrugations (11) are substantially free to move in the stacking direction along the inner wall of the housing (20).

5. Storage cell according to one of the preceding claims, wherein - the electrode stack (40) and the bellows (10) each have a central opening through which an inner tube (46) is guided for contact access of the electrode stack (40); and - the bellows (10) is movable in the stacking direction in the housing (20) along the inner tube (46).

6. Storage cell according to one of the preceding claims, wherein - the bellows (10) has a pressure surface (13) which is in active contact with the lower side of the electrode stack (40); and - the pressure surface (31) is designed for exerting the compression pressure onto the lower side (21) of the electrode stack (40).

7. The memory cell according to one of the preceding claims, wherein The pressure surface (31) and the housing cover enclose a safety volume (12) in the region of the bellows (10) and the safety volume (12) is connected by means of the inner tube (46) for receiving gas from the electrode stack (40).

8. Storage cell according to one of the preceding claims, wherein - a pressure plate (15) is non-movably connected in the housing (10) with a housing cover (16) at the housing upper side (13) and rests on the upper side (22) of the electrode stack (40); and - the pressure plate (15) is designed for exerting a pressure directed opposite to the compression pressure onto the upper side (22) of the electrode stack (20).

9. Memory cell according to one of the preceding claims, wherein The pressure plate (32) is designed for controlled rupture and / or deformation in the event of a thermal event.

10. Method for setting a compression pressure of an electrochemical storage cell, comprising the following steps: - providing an electrochemical storage cell with a housing (20) comprising a housing jacket (21), a housing lower side and a housing upper side, wherein an electrode stack (40) is arranged in an interior space of the housing (20) which is delimited by the housing jacket (21) between the housing lower side and the housing upper side; - setting the compression pressure by means of a bellows (10) which is connected at the housing lower side with the housing jacket (21), wherein the bellows (10) is elastically deformed by the compression pressure and exerts the compression pressure on the electrode stack (40); and - closing the housing (20) such that the set compression pressure is maintained.

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