ELECTROCHEMICAL ENERGY STORAGE CELL

Description

[0001] The present invention relates to an electrochemical energy storage cell with a cylindrical housing and a hollow cylindrical wound composite body and a method for producing such an electrochemical energy storage cell.

[0002] An electrochemical energy storage cell, as defined in the present application, is understood to be an electrochemical cell comprising at least one positive and at least one negative electrode, separated from one another by a separator, and capable of absorbing, storing, and releasing electrical energy as needed. During the absorption (charging of the cell) and release (discharging of the cell) of electrical energy, an electrochemical reaction takes place, which consists of two electrically coupled but spatially separated partial reactions. One partial reaction, taking place at a comparatively lower redox potential, takes place at the negative electrode, and one, taking place at a comparatively higher redox potential, takes place at the positive electrode.During discharge, electrons are released at the negative electrode through an oxidation process, resulting in an electron flow via an external load to the positive electrode, from which a corresponding amount of electrons is absorbed. A reduction process therefore takes place at the positive electrode. At the same time, an ionic current corresponding to the electrode reaction occurs within the electrochemical cells for the purpose of charge equalization. This ionic current passes through the separator and is maintained by an ion-conducting electrolyte.

[0003] In secondary (rechargeable) electrochemical energy storage cells, the discharge reaction is reversible, meaning that it is possible to reverse the conversion of chemical energy into electrical energy during discharge.

[0004] When the terms "anode" and "cathode" are used in connection with secondary electrochemical energy storage cells, the electrodes are usually named according to their discharge function. The negative electrode in such cells is the anode, and the positive electrode is the cathode.

[0005] In energy storage cells, the electrodes and separators are often provided in the form of composite bodies. Such a composite body can be a cell stack consisting of several cells. However, the composite body usually has a structure of wound electrodes and separators (wound composite body).

[0006] In the composites, positive and negative electrodes, which are preferably designed as flat strips coated on both sides, as well as separators or separator strips, lie flat on top of one another. The electrodes and separators can be connected to each other, for example, by lamination or adhesive bonding. Composites, regardless of whether they are wound or not, generally comprise the sequence positive electrode / separator / negative electrode. Composites are also frequently manufactured as so-called bicells with the possible sequences negative electrode / separator / positive electrode / separator / negative electrode or positive electrode / separator / negative electrode / separator / positive electrode.

[0007] The strip-shaped electrodes typically each comprise an electrically conductive current collector as well as electrochemically active components (often referred to as active materials) and electrochemically inactive components. The current collectors serve to electrically contact the electrochemically active components over as large an area as possible. They typically consist of strip-shaped, flat metal substrates, for example, metal foils, a metal foam, a metal mesh, a metal grid, or a metallized fleece. Porous plastic films, for example, made of a polyolefin or a polyether ketone, are particularly suitable as separators for the wound composite bodies.

[0008] To produce electrodes for wound composite bodies, pastes—comprising the aforementioned electrochemically active components and, as an electrochemically inactive component, an electrode binder (and optionally a conductive agent)—are typically applied in the form of thin layers to the aforementioned current collectors, dried, and formed into the desired shape. The layers are typically rolled and pressed after drying.

[0009] To produce the wound composite body, the band-shaped positive and negative electrodes thus formed are fed together with one or more band-shaped separators to a winding device and wound therein, preferably spirally around a winding axis. For this purpose, the electrodes and the separator are frequently wound onto a cylindrical or hollow-cylindrical winding core which sits on a winding mandrel and remains in the wound composite body after winding. In other embodiments, the winding can also be produced without a central winding core by forming the electrode composite directly on the winding mandrel. After a usually predefined number of turns (a turn is understood to mean each complete revolution of an electrode, for example, around the winding core or the winding mandrel), the winding process is terminated.This usually results in a wound composite body with a hollow cylindrical shape, which has an inner, axially aligned cavity.

[0010] The electrical contact between the electrodes of the wound composite body can be achieved, for example, via conductor lugs that protrude from the front of the formed wound composite body. The conductor lugs can be welded to the current collectors or be part of them.

[0011] Cylindrical designs are common for electrochemical energy storage cells, with the electrodes typically located as part of a hollow cylindrical wound composite body within a cylindrical housing. These can be cylindrical round cells or button cells.

[0012] Such an energy storage cell is disclosed, for example, in DE 20 2015 004 285 U1. Furthermore, the basic structure of button cells with lithium-ion-based windings produced by spirally winding strip-shaped electrodes and at least one strip-shaped separator is known, for example, from WO 2010 / 146154 A2, WO 2012 / 048995 A1, and WO 2010 / 089152 A1.

[0013] From WO 2010 / 089152 A1, an energy storage cell with a spiral-shaped wound composite body is known, wherein a slotted winding core with radially self-expanding properties is arranged in the center of the wound composite body.

[0014] US 2003 / 0134184 A1 discloses in Figure 16 a slotted winding core which is arranged in an axial cavity of a spirally constructed wound composite body of an energy storage cell.

[0015] A problem with such energy storage cells with a spiral-shaped wound composite body is locally occurring irregularities in the spiral structure of the wound composite body. Such irregularities tend to occur in areas where one of the wound electrode strips ends and / or where a sudden change in the thickness of one of the electrode strips occurs. Each of the electrode strips of a coil has an inner end near the winding core or the axially aligned cavity and an outer end near the outside of the coil. The distance of the electrode strips from the winding axis increases continuously from their inner end to their outer end over almost the entire length of the electrode strips. An irregularity results from a locally occurring discontinuity with regard to the change in the distance of the electrode strips from the winding axis.A sudden change in thickness and / or the end of an electrode strip can cause sudden changes in direction in the windings of adjacent electrode strips. This can lead to local mechanical stress if the electrode strips are subject to volumetric changes during charging and discharging, as the resulting pressures are not evenly distributed. Particularly problematic in this case is the volume expansion of the anode or the anodic coating when charging the energy storage cell. This increases the overall diameter of the entire wound composite body, resulting in pressure being exerted by the wound composite body toward the winding core located in the center of the wound composite body and also toward the housing surrounding the wound composite body.

[0016] The resulting mechanical stresses can have a very detrimental effect on the function of the energy storage cell. In addition to mechanical damage to the separator, for example, which can result from a collision with a current collector, this can impede ion exchange or, in the case of lithium-ion cells, even lead to lithium plating. Lithium plating generally refers to the deposition and deposition of metallic lithium on the anode. This can lead to the formation of dendrites, which can pierce the separator and thus cause a short circuit between the anode and cathode.

[0017] The invention, in contrast, aims to provide an improved energy storage cell that addresses the aforementioned problems. In particular, the uneven pressure distributions within the energy storage cell that occur during charging and discharging are to be avoided, thus preventing ion exchange and lithium plating.

[0018] This object is achieved by an electrochemical energy storage cell having the features of claim 1. Preferred embodiments of this energy storage cell are the subject of the claims dependent on claim 1. Furthermore, this object is achieved by a method for producing an electrochemical energy storage cell according to the independent method claim, wherein advantageous embodiments of this method arise from the claim dependent on this claim.

[0019] The electrochemical energy storage cell according to the invention always has the following features: a. The energy storage cell has a cylindrical housing enclosing an interior space with a top and a bottom side and a circumferential housing shell located therebetween. b. The housing shell has an inner housing shell surface that delimits the interior space to the outside. c. Arranged in the interior space is a hollow-cylindrical wound composite body which has a spiral structure made up of at least two electrode strips wound spirally around a winding axis and at least one separator strip arranged between the electrode strips. d. The electrode strips each comprise a strip-shaped current collector with an active material coating on both sides. e. The hollow-cylindrical wound composite body comprises two terminal end faces, a circumferential outer composite body shell surface and a circumferential inner composite body shell surface. f.The inner composite body surface defines an axially aligned cavity in the center of the wound composite body. g. A winding core with a substantially cylindrical or hollow-cylindrical shape is arranged in the axially aligned cavity, which has an outer circumferential surface that lies flat against the inner composite body surface. . Furthermore, the energy storage cell according to the invention is characterized by the following feature: i.e. the winding core has a local deviation from the cylindrical or hollow cylindrical shape in at least one area of ​​the outer peripheral surface.

[0020] In other words, the outer peripheral surface of the winding core has at least one adjustment or change in shape that deviates from a cylindrical or hollow cylindrical shape. These adjustments or changes serve to compensate for irregularities in the spiral structure of the wound composite body.

[0021] The expression "in at least one region of the outer peripheral surface" means that several regions may be provided that exhibit a local deviation from the cylindrical or hollow-cylindrical shape. This does not necessarily have to involve the same deviation in different regions. Rather, two or more regions may be provided in which different deviations from the cylindrical or hollow-cylindrical shape of the winding core are provided. When reference is made below to a local deviation in a region of the outer peripheral surface, this refers to a deviation according to the aforementioned feature h.

[0022] The aforementioned feature h. ensures that the pressure peaks that occur locally, particularly during charging or discharging of the wound composite body in areas of irregularities in the spiral structure of the wound composite body, can be compensated for. In particular, a locally increased pressure in the central region of the wound composite body, which can occur particularly during the charging process, can be compensated for by the local deviation provided according to the invention in an area of ​​the outer circumferential surface of the wound composite body. The above-described risk of impeding ion exchange and - in the case of a lithium-ion cell - the risk of lithium plating, are significantly reduced, particularly in these areas. Overall, the reliability and service life of the energy storage cell can thus be improved or extended.

[0023] The axially aligned cavity, which is defined by the inner surface of the composite body and is located in the center of the wound composite body, preferably has openings on both end faces. Thus, in preferred embodiments, the cavity is partially filled by the winding core. If the winding core is not a hollow cylindrical winding core but a solid winding core, the cavity is completely filled.

[0024] The terminal end faces of the hollow-cylindrical wound composite body are, in particular, essentially circular end faces, whereby in this context the term "essentially" refers to the fact that the aforementioned irregularities that may occur in the spiral structure of the wound composite body may lead to a deviation from an ideal circular shape in some areas.

[0025] The substantially cylindrical or hollow-cylindrical shape of the winding core according to the aforementioned feature g. refers to the fact that the winding core has a cylindrical or hollow-cylindrical basic shape, but that according to the aforementioned feature h. one or more deviations from the cylindrical or hollow-cylindrical shape can be provided.

[0026] The electrochemical energy storage cell according to the invention has the two following additional features i. and j.: i. The spiral structure of the wound composite body comprises at least one local irregularity in at least one region where one of the wound electrode strips ends and / or a sudden change in the thickness of one of the electrode strips occurs. j. The at least one region of the outer peripheral surface of the winding core in which the local deviation from the cylindrical or hollow-cylindrical shape occurs is spatially associated with a local irregularity of the wound composite body.

[0027] The local irregularities that can occur at various points in the spiral structure are equivalent to the irregularities in the spiral structure discussed above. Areas where one of the wound electrode strips ends and / or a sudden change in the thickness of one of the electrode strips occurs primarily in the central and outer regions of the wound composite body. The irregularities in the spiral shape of the wound composite body manifest themselves particularly in locally occurring discontinuities regarding the change in the distance between electrode strips and the winding axis. For example, in the area of ​​the end of an electrode strip, a sudden change in direction can occur in an adjacent electrode strip that overlaps the end.

[0028] It is generally preferred that the outer turns of the wound composite body be formed solely by the separator strips, thus insulating the electrode strips from the outside. Furthermore, the outer and inner ends of the anode and cathode are generally not located at the same position in the electrode assembly. Each end of the anode and cathode represents a defect in the winding structure and results in irregularities in the winding structure.

[0029] Furthermore, it is generally preferred that the current collectors of the electrodes not be coated with electrode material at their ends. For example, the inner windings of the wound composite body can be formed solely by the anode current collector. At the point where the coating with active material begins, a gradual or sudden change in the thickness of the electrode strip occurs, thus creating another defect. Due to the manufacturing process, the coating thickness often reaches a maximum at the beginning and end of a coating with an electrode material, which may further accentuate the irregularities in these areas.

[0030] Furthermore, defects can occur if the coatings on both sides of the cathode and / or the anode are not exactly opposite each other at their starting points, but are offset. The coatings on the anode are particularly important, as the active material of the anode is often subject to particularly strong volume fluctuations during charging and discharging of the energy storage cell.

[0031] By spatially matching the local deviation in the area of ​​the outer circumferential surface of the winding core to the local irregularity of the wound composite body, the consequences caused by the imperfections are compensated. For example, if a defect causes local pressure on the winding core, this is compensated by the winding core having a recess into which the wound composite body can relax.

[0032] The spatial assignment can be achieved in particular by a direct spatial bordering of the local deviation to the fault location or the local irregularity.

[0033] The spatial assignment continues to consist in the fact that the local deviation in the area of ​​the outer circumferential surface is intersected by a straight line passing through the winding axis and the local irregularity in the spiral structure.

[0034] Particularly preferably, the local deviation is spatially assigned to a local defect caused by a transition region in the active material coating of the anode.

[0035] In a further particularly preferred embodiment of the electrochemical energy storage cell according to the invention, the energy storage cell is characterized by at least one of the immediately following additional features a. and b.: a. The local deviation from the cylindrical or hollow-cylindrical shape consists of a stepped or continuous reduction and / or expansion of the outer diameter of the winding core. b. The local deviation consists of at least one stepped or continuous reduction and / or expansion of the outer diameter of the winding core, wherein the at least one stepped or continuous reduction and / or expansion of the outer diameter extends axially over the preferably entire height of the winding core. Particularly preferably, the immediately above features a. and b. are implemented in combination.

[0036] The stepped or continuous reduction and / or expansion of the outer diameter of the winding core can, depending on the viewing direction, be a local decrease or a local increase in the outer diameter. Particularly preferably, this reduction and / or expansion of the outer diameter, and thus the local deviation, extends axially over the preferably entire height of the winding core. This is based on the fact that local defects, i.e. the described irregularities in wound composite bodies, generally extend over the entire height of the wound composite bodies, so that this configuration allows the deviation to compensate for the axially extending defect in a particularly suitable manner.

[0037] In particular, a stepped reduction and / or expansion of the outer diameter of the winding core can compensate for abrupt imperfections or other extreme imperfections in the spiral structure of the wound composite body. It is also possible to provide continuous reductions and / or expansions in the outer circumferential surface. Combinations of stepped and continuous reductions / expansion can also be provided, for example, with a continuous reduction of the outer diameter in one direction followed by a stepped expansion of the outer diameter. This effectively forms an axially aligned notch in the outer circumferential surface of the winding core, with a gentle slope on one side and an abrupt slope on the other.

[0038] With regard to the design of the local deviation in the outer peripheral surface of the winding core, the electrochemical energy storage cell according to the invention can further be characterized by at least one of the following additional features a. and b.: a. The local deviation in at least one region of the outer peripheral surface of the winding core consists of a depression in the outer peripheral surface of the winding core and / or a curvature of the outer peripheral surface of the winding core. b. The local deviation in at least one region of the outer peripheral surface of the winding core consists of a depression in the outer peripheral surface of the winding core and / or a curvature of the outer peripheral surface of the winding core, wherein the depression and / or the curvature extend axially over the preferably entire height of the winding core.

[0039] Particularly preferably, the immediately above features a. and b. are implemented in combination.

[0040] The term "recess" in the outer peripheral surface of the winding core refers specifically to a concave indentation in the outer peripheral surface. The term "curvature" refers specifically to a convex bulge in the outer peripheral surface.

[0041] In preferred embodiments, the recess extends over the entire height of the winding core, for example, in the form of a groove. The curvature can, for example, be designed as a web, which in preferred embodiments extends over the entire height of the winding core. It can also be provided that a recess and a curvature are combined to form a counterpart for a defect in the outer circumferential surface of the winding core, in order to accommodate excessively expanding areas and, at the same time, to provide support to prevent displacement of the spiral structure.

[0042] By applying the various options for designing the local deviation, a winding core can be provided that is able to optimally compensate for one or more local defects in the wound composite body. Depending on the degree of severity of the defect, a corresponding deviation can be realized in an area of ​​the outer circumferential surface, which can compensate for the uneven pressure distributions associated with the defect. For example, a depression can be used to compensate for a locally increased expansion of the wound composite body. A curvature in the outer circumferential surface of the winding core, for example, can locally prevent a displacement of the spiral structure if adjacent areas in the spiral structure expand excessively. Accordingly, combinations of depressions and curvatures can be used with particular preference.

[0043] In particularly preferred embodiments, the winding core has a local deviation from the cylindrical or hollow-cylindrical shape in two or more regions of the outer circumferential surface, each of which is spatially associated with a local defect. The number of local deviations depends in particular on the number and position of the local defects in the respective wound composite body that arise during the production of the wound composite body.

[0044] In a particularly preferred embodiment of the electrochemical energy storage cell according to the invention, the energy storage cell is characterized by at least one of the immediately following features a. to c.: a. The winding core is designed as a hollow cylinder and has an inner core surface that defines an axially aligned cavity inside the winding core. b. The winding core has a local deviation in the form of a depression in the outer circumferential surface and a corresponding bulge extending into the axially aligned cavity. c. The winding core has a local deviation in the form of a bulge in the outer circumferential surface and a corresponding bulge in the inner core surface.

[0045] Particularly preferably, the immediately above features a. and b. or a. and c. or a. to c. are implemented in combination.

[0046] If the local deviation of a hollow cylindrical winding core has a counterpart inside the winding core, this has the advantage that the local deviation can be precisely positioned for the winding process using suitable tools, for example, a correspondingly counter-shaped winding mandrel that is inserted into the interior of the winding core. In particular, the above-described spatial assignment of the deviation to the local defects in the wound composite body can be realized in a particularly accurate and precise manner.

[0047] It is not absolutely necessary for the inner core surface of the winding core to exactly replicate the outer circumferential surface with the deviation(s). A gradual change in the outer circumference can, for example, also be replicated by a continuous change in the inner circumference.

[0048] Winding cores according to the immediately preceding features a. to c. particularly preferably have a substantially uniform wall thickness.

[0049] In a particularly preferred embodiment of the energy storage cell, it is provided that the winding core has, as a local deviation, the aforementioned axially aligned notch or another axial depression in the outer circumferential surface of the winding core and that one end of one of the electrode strips or one end of one of the separator strips is arranged in this depression.

[0050] This is based on the fact that the inner end of an electrode strip forms an edge in the winding direction, over which a subsequent turn is placed during winding, which almost inevitably leads to a defect in the winding structure. This problem can be avoided or at least reduced by placing the end in the notch or recess. Ideally, the occurrence of an edge over which winding must be carried out can be completely avoided.

[0051] In some embodiments, it is common practice to weld the electrode assembly to the winding core at the starting point of the winding during the manufacture of a wound composite body. This welding generally results in a local thickening, which disrupts the structure of the immediately following and possibly further subsequent windings located above the thickening. For example, the welding can also create a disruptive edge.

[0052] When the separator belt(s) are fastened in the notch or recess in the outer peripheral surface of the winding core, the occurrence of thickenings has no effect as long as a resulting edge does not protrude from the notch or recess.

[0053] In a further preferred embodiment, the electrochemical energy storage cell according to the invention is characterized by the immediately following additional feature a.: a. The local deviation in at least one region of the outer circumferential surface of the winding core designed as a hollow cylinder comprises an opening in the wall of the winding core, in particular a slot in the wall.

[0054] The perforation in the wall can, in particular, extend over the entire height of the winding core. A slot or gap designed in this way allows the local deviation to act as a clamping element. At the beginning of a winding process, for example, a separator strip can be clamped into the slot, eliminating the need to weld the electrode assembly to the winding core.

[0055] In this context, it can be particularly advantageous for the ends of the winding core wall interrupted by the slot to overlap, thus achieving a particularly advantageous clamping effect. Alternatively, it can also be provided that the end faces of the hollow cylinder wall that border the slot meet directly when pressed together.

[0056] Furthermore, it can be provided that the electrochemical energy storage cell according to the invention is characterized by one of the following features: a. The outer peripheral surface of the winding core has one or more recesses for accommodating at least one sensor. b. The outer peripheral surface of the winding core has one or more recesses for accommodating at least one sensor, wherein the recess or recesses extend axially over the preferably entire height of the winding core.

[0057] This embodiment is based on the fact that monitoring the operation of energy storage cells is useful and / or necessary for many applications. It is therefore known to integrate sensors into electrochemical energy storage cells, for example, to record data on the temperature and / or pressure within the cell. Furthermore, chemical sensors or voltage sensors, for example, are known in connection with energy storage cells. Using the sensors in an energy storage cell, the condition of the energy storage cell can be monitored and / or diagnosed.

[0058] The energy storage cell according to the invention therefore preferably provides for one or more depressions to be provided as local deviations in the outer circumferential surface of the winding core, said depressions serving to accommodate one or more sensors. Depending on the intended position of the sensor in the energy storage cell, the depression can extend more or less axially over the height of the winding core. Several depressions can also be provided at different positions in the outer circumferential surface of the winding core to accommodate several sensors. With this possible position of one or more sensors in the energy storage cell, in particular the conditions in the center of the wound composite body and thus inside the energy storage cell can be detected.

[0059] Suitable sensors for this embodiment of the energy storage cell according to the invention are, for example, a reference electrode for measuring the electrode potential of the cell and / or a temperature sensor for temperature monitoring, in particular for detecting excessive heating, and / or a pressure sensor with which, for example, excessive pressure development, in particular an increase in the internal cell pressure, can be detected.

[0060] When designing the outer peripheral surface of the winding core, an electrical conductor and similar structural elements provided in the center of the wound composite body can also be taken into account. For example, one or more recesses can be provided in the outer peripheral surface of the winding core as local deviations, providing space for these additional structural elements and / or this electrical conductor.

[0061] In a particularly preferred manner, the electrochemical energy storage cell according to the invention is characterized by the following additional feature a.: a. the winding core is made of plastic or a plastic composite material.

[0062] Plastic is a widely used material for the production of winding cores and can be easily processed for the purposes of the invention. For example, winding cores with the inventive local deviations from the cylindrical or hollow-cylindrical shape can be manufactured as injection-molded parts. Another possibility is an extrusion process for the production of the winding cores. Similarly, plastic composite materials can be used for the production of the winding cores. Plastic and plastic composite materials also have the advantage that they are lightweight and do not contribute significantly to the weight of the resulting energy storage cell. Furthermore, they are electrically insulating and are therefore particularly suitable for the energy storage cells according to the invention as a material for the winding core.

[0063] The energy storage cell according to the invention preferably has a cylindrical housing. "Cylindrical" is not to be understood in the strictly geometric sense. The housing may well have deviations from a perfect cylinder, for example, in the area of ​​a terminal housing closure or on the top or bottom, which do not necessarily have to be completely flat. Preferably, the housing shell or at least a segment of the housing shell has a largely or completely constant outer radius and, in some embodiments, is very close in shape to a perfect circular cylinder.

[0064] The housing is, in particular, a metallic housing, preferably formed from a positively polarized and a negatively polarized metallic housing part. The housing parts can be made, for example, of nickel-plated sheet steel, stainless steel (e.g., type 1.4303 or 1.4304), copper, nickel-plated copper, or alloyed or unalloyed aluminum. It may also be preferred for the housing parts electrically connected to the cathode to be made of aluminum or an aluminum alloy, and for the housing parts electrically connected to the anode to be made of copper, a copper alloy, or nickel-plated copper.

[0065] The positively polarized and the negatively polarized housing parts can, for example, be cup-shaped. They then each have a circular cup base, a circumferential cup wall, a cup rim with a terminal cutting edge, and a cup opening defined by the cup rim. The cup walls can preferably be described as annular segments of a hollow cylinder with a circular cross-section. Their diameters preferably either correspond exactly to those of the respective corresponding circular base or are located above them. As a rule, the cup walls are aligned orthogonally to the corresponding bases. When assembled, the cup bases correspond to the top and bottom of the housing, while the cup walls form the annular, circumferential housing shell.

[0066] It is also possible that one of the housing parts (positive or negative) is cup-shaped and has a circular opening, while the reversely polarized housing part is designed as a disc or includes a disc that closes the opening.

[0067] An annular electrically insulating seal is preferably arranged between the housing parts.

[0068] With regard to the design of the housing shell and in particular the inner housing shell surface, in a particularly preferred embodiment of the electrochemical energy storage cell according to the invention, at least one of the immediately following additional features a. and b. is provided: a. The housing shell has a hollow cylindrical shape. b. The housing shell has a local deviation from the hollow cylindrical shape in at least one region of its inner surface.

[0069] Particularly preferably, the immediately above features a. and b. are implemented in combination.

[0070] This embodiment is based on the fact that the above-described irregularities in the spiral structure of the wound composite body can also occur in the outer region of the wound composite body, which can lead to uneven compressive loads in the outer region of the wound composite body. Since the wound composite body, with its outer circumferential surface, preferably borders flatly on the inner housing surface, such irregularities in the spiral structure and their adverse effect on the function of the energy storage cell can be compensated for by the deviations from the hollow cylindrical shape. The irregularities in outer regions of the wound composite body manifest themselves in particular in a deviation from an ideal cylindrical shape orHollow cylindrical shape in the outer circumference of the wound composite body, which has a negative effect, particularly during expansion and shrinkage of the wound composite body during charging and discharging of the energy storage cell. To compensate for such irregularities, deviations are preferably provided on the inner housing surface in at least one area, similar to the local deviation(s) explained above in the at least one area of ​​the outer circumferential surface of the winding core.

[0071] While the above-described local deviations in regions of the outer circumferential surface of the winding core serve to compensate for imperfections in the region of the inner composite body surface, the deviations in the at least one region of the inner housing surface are primarily suitable for compensating for imperfections in the region of the outer composite body surface of the wound composite body. The measures according to the invention follow the principle that the shape of the inner housing surface follows the course of the irregularities on the outer circumference of the wound composite body, so that the outer composite body surface can adhere to the inner housing surface without discontinuities.

[0072] In a particularly advantageous manner, the local deviations in at least one region of the outer circumferential surface can be combined with the local deviations in the at least one region of the inner housing surface, so that all irregularities that may occur in the inner region and in the outer region of the wound composite body can be compensated.

[0073] However, it is also possible for deviations to be provided exclusively on the outer peripheral surface of the winding core or exclusively on the inner housing surface. In principle, embodiments in which the housing shell has a local deviation from the hollow cylindrical shape in at least one region of its inner housing surface can therefore also be implemented independently of feature h of claim 1.

[0074] The energy storage cell according to the invention is preferably characterized by the immediately following additional feature a.: a. The at least one region of the inner housing surface which has the deviation is spatially assigned to a local defect in the wound composite body.

[0075] Through this local allocation, which can be configured in a manner analogous to that described for the winding core, the energy storage cell according to the invention allows compensation for pressure acting locally in the outer circumference of the wound composite body as a result of irregularities or defects in the outer region of the spiral structure of the wound composite body. In the outer region of the spiral structure of the wound composite body, the end of the cathodic electrode strip and the end of the anodic electrode strip in particular contribute to such defects. In general, two defects in the outer circumference of such wound composite bodies occur primarily, which are caused by the end of the respective electrode strips in the outer circumference of the wound composite body. These two defects in particular can be compensated for by corresponding local deviations of the housing shell from the hollow cylindrical shape.

[0076] With regard to the design of this local deviation of the inner housing surface, the energy storage cell according to the invention is characterized in particular by at least one of the immediately following additional features a. to d.: a. The local deviation consists in a stepped or continuous reduction and / or widening of the inner diameter of the housing shell. b. The local deviation consists in a stepped or continuous reduction and / or widening of the inner diameter of the housing shell, wherein the stepped or continuous reduction and / or widening of the inner diameter extends / extends axially over preferably the entire height of the housing. c. The local deviation consists in a depression in the inner housing shell surface and / or a curvature of the inner housing shell surface. d. The local deviation consists in a depression or curvature in the inner housing shell surface and / or a curvature of the inner housing shell surface, wherein the depression and / or curvature extends / extends axially over preferably the entire height of the housing.

[0077] Combinations of recesses and bulges, which can be provided together, are particularly suitable. For example, a recess can absorb or accommodate excessive local expansion during charging / discharging processes, while a bulge can maintain and support the spiral structure in its shape.

[0078] To create the recesses and bulges, the housing shell may be subjected to targeted deformation. For example, bars made of plastic or another material can be fixed to the inner surface of the housing shell.

[0079] To realize the local deviation from the hollow cylindrical shape of the housing shell, the housing shell can also be reinforced by an annular insert that rests against the inside of the housing shell. The insert preferably has a height in the range of 50% to 100% of the height of the housing shell. The insert can have a thickness that is on the order of magnitude of the thickness of the housing shell. A local reduction in the inner diameter of the housing shell can be realized, for example, by using an annular insert that has an increased thickness in at least one section. A local expansion of the inner diameter of the housing shell can be realized, for example, by using an annular insert that has a reduced thickness in at least one section.

[0080] For a local expansion of the inner diameter of the housing shell, a band-shaped insert can also be used. This insert rests against the inside of the housing shell over its entire length, but cannot completely cover the inside because it is shorter than the inner circumference of the housing shell. This insert also preferably has a height in the range of 50% to 100% of the height of the housing shell and can have a thickness that is on the order of magnitude of the thickness of the housing shell.

[0081] The energy storage cell according to the invention is particularly preferably a secondary lithium-ion cell. Lithium-ion cells are generally characterized by the fact that they comprise electrodes that can reversibly absorb and release lithium ions. They also contain an electrolyte containing lithium ions. Suitable active materials for the electrodes of lithium-ion cells include all materials that can absorb and release lithium ions.

[0082] Carbon-based materials such as graphitic carbon or non-graphitic carbon materials capable of intercalating lithium are particularly suitable for the negative electrode of secondary lithium-ion cells. Furthermore, metallic and semi-metallic materials that can be alloyed with lithium can also be used. For example, the elements tin, antimony, and silicon are capable of forming intermetallic phases with lithium. In particular, the carbon-based active materials can also be combined with the metallic and / or semi-metallic materials. Alternatively or additionally, lithium titanate (Li 4 Ti 5 O 12 ) or a derivative thereof can also be contained in the negative electrode.

[0083] For the positive electrode of lithium-ion cells, and in particular of secondary lithium-ion cells, lithium metal oxide compounds and lithium metal phosphate compounds such as LiCoO 2 and LiFePO 4 are suitable. Also particularly suitable are lithium nickel manganese cobalt oxide (NMC) with the molecular formula LiNi x Mn y Co z O 2 (where x + y + z is typically 1), lithium manganese spinel (LMO) with the molecular formula LiMn 2 O 4 , or lithium nickel cobalt aluminum oxide (NCA) with the molecular formula LiNi x Co y Al z O 2 (where x + y + z is typically 1). Mixtures of the materials mentioned can also be used.

[0084] Electrode binders and conductive materials are the most important electrochemically inactive components for lithium-ion cells. Electrode binders ensure the mechanical stability of the electrodes and ensure contact between the particles of electrochemically active material and the current collector. Common electrode binders are based on polyvinylidene fluoride, polyacrylate, or carboxymethylcellulose, for example. Conductive materials such as carbon black serve to increase the electrical conductivity of the electrodes.

[0085] Porous plastic films, such as polyolefin or polyether ketone, are particularly suitable as separators for lithium-ion cells. Nonwovens and fabrics made from these materials can also be used.

[0086] As an ion-conducting electrolyte, lithium-ion cells can contain, for example, a mixture of organic carbonates in which a lithium salt is dissolved. Basically, any lithium salt known from the state of the art for lithium-ion cells is suitable for this purpose. A prominent example of this is lithium hexafluorophosphate (LiPF 6 ). The electrodes and separators of lithium-ion cells are preferably impregnated with the electrolyte.

[0087] In a particularly preferred manner, the energy storage cell according to the invention is characterized by one of the following additional features: a. the electrochemical energy storage cell is a cylindrical round cell, in particular a secondary lithium-ion cell in the form of a cylindrical round cell, or b. the electrochemical energy storage cell is a button cell, in particular a secondary lithium-ion cell in the form of a button cell.

[0088] Cylindrical round cells have a height that is greater than their diameter. They are particularly suitable for applications in the automotive sector, e-bikes, or other applications with high energy requirements.

[0089] The height of lithium-ion cells designed as round cells is preferably in the range of 15 mm to 150 mm. The diameter of cylindrical round cells is preferably in the range of 10 mm to 60 mm. Within these ranges, form factors of, for example, 18 x 65 (diameter times height in mm) or 21 x 70 (diameter times height in mm) are particularly preferred. Cylindrical round cells with these form factors are particularly suitable for supplying power to electric motor vehicles.

[0090] The nominal capacity of a lithium-ion cell according to the invention designed as a cylindrical round cell is preferably up to 90,000 mAh. With a form factor of 21 x 70, the cell in one embodiment as a lithium-ion cell preferably has a nominal capacity in the range of 1,500 mAh to 7,000 mAh, particularly preferably in the range of 3,000 to 5,500 mAh. With a form factor of 18 x 65, the cell in one embodiment as a lithium-ion cell preferably has a nominal capacity in the range of 1,000 mAh to 5,000 mAh, particularly preferably in the range of 2,000 to 4,000 mAh.

[0091] In the European Union, manufacturer specifications regarding the nominal capacities of secondary energy storage cells are strictly regulated. For example, specifications regarding the nominal capacity of secondary nickel-cadmium energy storage cells must be based on measurements according to the standards IEC / EN 61951-1 and IEC / EN 60622; specifications regarding the nominal capacity of secondary nickel-metal hydride energy storage cells must be based on measurements according to the standard IEC / EN 61951-2; specifications regarding the nominal capacity of secondary lithium-ion cells must be based on measurements according to the standard IEC / EN 61960; and specifications regarding the nominal capacity of secondary lead-acid cells must be based on measurements according to the standard IEC / EN 61056-1. Any specifications regarding nominal capacities in this application are preferably also based on these standards.

[0092] Like cylindrical round cells, button cells are also cylindrical. However, they have a height (preferably in the range of 4 mm to 15 mm) that is equal to or preferably less than their diameter (preferably in the range of 5 mm to 25 mm). They are particularly suitable for supplying electrical energy to small electronic devices such as watches, hearing aids, and wireless headphones.

[0093] The nominal capacity of the energy storage cell according to the invention, designed as a button cell, is preferably up to 1500 mAh in one embodiment as a lithium-ion cell. More preferably, the nominal capacity is in the range of 100 mAh to 1000 mAh, particularly preferably in the range of 100 to 800 mAh.

[0094] The invention also includes a method for producing an electrochemical energy storage cell, which is characterized by the following method steps: a. At least two electrode strips are provided, each with a strip-shaped current collector with an active material coating on both sides and at least one separator strip arranged between the electrode strips. b. A winding core with a substantially cylindrical or hollow-cylindrical shape is provided, which has an outer circumferential surface, wherein the outer circumferential surface of the winding core has a deviation from a cylindrical or hollow-cylindrical shape in at least one region. c. To produce a wound composite body, the electrode strips and the at least one separator strip are wound spirally around the winding core to form a spiral structure, wherein the winding is carried out in such a way that the deviation is spatially assigned to a local defect in the spiral structure. d. A cylindrical housing for the energy storage cell is provided. e.The wound composite body is inserted into the housing, f. The wound composite body is electrically contacted and the housing is closed. .

[0095] The core of this process is that a substantially cylindrical or hollow-cylindrical winding core is used to produce the wound composite body, with the outer peripheral surface of the winding core exhibiting a deviation from a cylindrical or hollow-cylindrical shape in at least one region. This deviation, or possibly several deviations, can be used to compensate for irregularities in the spiral structure of the wound composite body.

[0096] The method further provides that the deviation of a local defect in the spiral structure of the wound composite body is spatially assigned so that the compensation of negative effects of an uneven pressure distribution caused by the structural irregularities can be carried out in a particularly effective manner.

[0097] In a particularly preferred manner, the spatial assignment is realized by using a correspondingly shaped winding mandrel, onto which the hollow-cylindrical winding core can be pushed, in order to realize appropriate positioning of the electrode assembly to be wound on the winding core. It is particularly advantageous if the inner wall of the hollow-cylindrical winding core directly or indirectly reflects the deviation in the outer circumference of the winding core, so that, for example, only one position of the correspondingly oppositely shaped winding mandrel is possible within the winding core. In this way, the correct localization of the winding core on the winding mandrel in relation to the wound composite body to be wound can be ensured.

[0098] The energy storage cell that can be manufactured using this method is, in particular, an energy storage cell with the features already explained above. For further features of the energy storage cell, and in particular of the winding core, and thus also for further features of the manufacturing method, reference is therefore also made to the above description.

[0099] Finally, the invention comprises a winding tool with which this manufacturing method can be carried out. In particular, the winding tool comprises a winding mandrel or the winding tool is a winding mandrel, wherein the winding mandrel is shaped to correspond to the winding core designed according to the invention. In particular, if the winding core is hollow cylindrical and the inner core surface of the winding core simulates the deviation or deviations on the outer circumferential surface of the winding core, such a winding mandrel preferably has an opposite shape in its outer circumferential surface which corresponds to the inner core surface of the winding core. The winding tool and in particular the winding mandrel can in a sense represent the interior of the winding core as a negative. In correspondence to the inner circumference orFor example, the winding mandrel can have a cam on the inner core surface of the winding core if the winding core has a recess at this position.

[0100] With such a winding tool, a wound composite body can be produced in a particularly practical manner in which the start of the winding on the winding core can be located very precisely and the spatial assignment of one or more deviations on the outer circumferential surface of the winding core to local defects in the wound composite body can be realized particularly precisely.

[0101] Further features and advantages of the invention will become apparent from the claims and the following description of preferred embodiments of the invention in conjunction with the drawings. The individual features may be implemented individually or in combination with one another. BRIEF DESCRIPTION OF THE DRAWINGS

[0102] In the drawings shows: Fig. 1 shows a cross-section through a wound composite body with a housing of an energy storage cell to illustrate the problem underlying the invention (prior art); Fig. 2 A, B shows possible embodiments of a hollow cylindrical winding core of the wound composite body of an energy storage cell according to the invention; Fig. 3 A, B shows further possible embodiments of a hollow cylindrical winding core of the wound composite body of an energy storage cell according to the invention; Fig. 4 shows a further possible embodiment of a hollow cylindrical winding core of the wound composite body of an energy storage cell according to the invention; Fig. 5 shows a possible embodiment of the housing of an energy storage cell according to the invention; Fig. 6 shows a possible embodiment of an energy storage cell according to the invention; and Fig. 7 shows a further possible embodiment of the housing of an energy storage cell according to the invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0103] Fig. 1 illustrates the problem with conventional energy storage cells with a hollow cylindrical wound composite body. The illustration is based on an x-ray image showing a cross-section through a button cell. However, the situation described can equally be found in cylindrical round cells. The wound composite body 1 is formed by spirally wound electrode strips with separator strips in between. The wound composite body 1 is located within an interior of the energy storage cell defined by a housing shell 2 of a cylindrical housing. In the center 3 of this conventional energy storage cell shown here, or in the center of the wound composite body 1, there is no winding core in this embodiment. Electrical contact is made with one of the electrodes via a metallic conductor 4 in the inner region of the wound composite body 1.

[0104] The layer thickness of the separator strips can, for example, be in the range of 20 µm. The layer thickness of the cathodic electrode strips can, for example, be in the range of 150 µm. The layer thickness of the anodic electrode strips can, for example, be in the range of 100 µm. Depending on the design, the thickness of the separators can also be approximately 12 µm or 16 µm. Depending on the design, the coated electrode strips can also have a thickness range of 110 µm ±15 µm.

[0105] In various areas of the spiral structure of the wound composite body 1, local defects 5, 6, 7, 8 can be seen, which are formed by various transition areas and ends of electrode strips during the production of the wound composite body 1.

[0106] When considering the spiral structure of the wound composite body 1 in Fig. 1 From the inside out, the winding initially begins exclusively with a few turns of the anode current collector, to which conductor 4 is welded. After a few turns, at the position designated as defect 5, there is a transition to a section of the anode current collector coated on both sides with an active material coating. The inner end of the cathodic electrode strip is located at the position designated as defect 6. In the outer region of the wound composite body 1, the end of the cathodic electrode strip is located at the position designated as defect 7. The outer end of the anode current collector is located at the position designated as defect 8. These defects 5, 6, 7, 8 in various areas of the spiral structure of the wound composite body 1 result in irregularities in the approximately circular shape of the individual turns, which can also affect neighboring turns.

[0107] Particularly in connection with volume expansion and contraction during charging and discharging processes, this causes uneven pressure distributions, which adversely affect the function of the energy storage cell. In particular, this can lead to microcircuits and short circuits due to increased stress on the separator at the unevenness, particularly at the beginning of the winding, i.e., in the center of the wound composite body 1, and / or adverse lithium plating.

[0108] To avoid these problems in wound composite bodies, the invention proposes a specific shape for a winding core located at the center of the wound composite body. Such a special shape of the winding core makes it possible, in particular, to avoid the problems that arise inside the wound composite body.

[0109] Fig. 2 shows two possible examples for the shape of the winding core 10. The winding core 10 has a deviation 11 from an ideal hollow cylindrical shape of the winding core in its outer circumferential surface (a cross-section is shown here), whereby a gradual widening of the outer diameter is realized in the sectional plane shown here when viewed from left to right (partial figure A). According to the invention, the deviation 11 can be used to connect the electrode assembly to the winding core 10 at this point, for example by welding or gluing the separator strips at this point. The special shape of the winding core 10 prevents edges or general irregularities in the developing spiral structure above the start of the winding at position 11 during subsequent windings.Overall, this significantly increases the homogeneity of the winding in its roundness, ensuring uniform tensile forces, especially during volume increases and decreases during charging and discharging processes in the energy storage cell. There are no localized compressive loads at transition points, thus avoiding the risk of cracking. Likewise, excessive stress on the separator, especially in the inner area of ​​the spiral structure of the wound composite body, is avoided, thus preventing, for example, lithium plating or other adverse effects of such irregularities.

[0110] In part B of the Fig. 2 A further possible embodiment of the winding core 10 with the deviation 11 in the outer circumference is shown, wherein an adjustment 12 in the wall thickness was made in the inner core surface of the hollow cylindrical winding core, which corresponds to the deviation 11 in the outer circumference. The deviation 11 in the form of the step-like increase in the outer circumference is depicted on the inner circumference in a continuous form as adjustment 12. The adjustment 12 on the inner core surface of the winding core 10 is therefore similar to or correspondingly shaped to the deviation 11 on the outer circumference of the winding core 10. This has the advantage that during production of the wound composite body, exact alignment to the start of the winding is possible in a particularly simple manner.

[0111] Depending on the dimensions of the energy storage cell, the dimensions of the winding core, which is preferably made of plastic, can be adjusted. For example, the outer diameter of the winding core for a button cell can be between 2 and 3 mm, e.g., 2.1 mm.

[0112] Fig. 3 shows further possibilities for designing the shape of the winding core 20. Here, in the hollow cylindrical shaped winding core 20 in partial figure A, there is a notch as a deviation 21, which on the left side shows a continuous transition to the wall thickness outside the local deviation 21 and which on the right side shows a gradual or abrupt transition to the wall thickness outside the deviation 21. In the local deviation 21 formed as a notch in the outer circumference of the winding core 20, for example, the separator strips forming the end of the electrode assembly can be attached to the winding core 20, e.g. by welding or gluing, so that no edges or similar distortions occur.

[0113] Furthermore, the winding core 20, or generally the winding core according to the invention, can contain further local deviations in the outer circumference, which can compensate for further transition areas or irregularities in the spiral structure of the wound composite body to be applied thereto. In particular, a corresponding taper or notch can be provided in the outer circumferential surface of the winding core at such defect areas where particular thickness changes occur due to the electrode coatings.

[0114] Part B of the Fig. 3 shows a further possible design of the winding core 20, wherein a similar shape of the inner core surface is realized at the position 22 opposite the deviation 21 in the outer circumferential surface of the winding core 20. As a result, the wall thickness in this area is optimized or compensated, whereby the Fig. 2 described advantages can be achieved.

[0115] Fig. 4 shows a further possible design for a winding core 30 with a deviation 31, which is designed to form a slot through the wall of the hollow-cylindrical winding core 30 with overlapping ends of the wall. This provides a clamping position with which, for example, one end of a separator belt can be clamped to the winding core 30, so that no further fastening, such as welding, is required, and at the same time, a uniform spiral structure can be achieved in the wound composite body.

[0116] In an analogous manner to the deviations in the outer circumferential surface of the winding core, the housing 50 surrounding the wound composite body can be designed with deviations in the inner circumferential surface in order to compensate for irregularities or defects in the outer region of the wound composite body. Fig. 5 shows a deviation 51 in the inner housing surface of the housing shell 50, wherein a curvature 52 in the direction of the wound composite body to be arranged inside is combined with a recess 53, in which the wall thickness of the housing shell 50 is reduced. The recess 53 can compensate for local pressure peaks as a result of uneven volume increases. The curvature 52 can provide a supporting structure to stabilize the spiral structure. Such a configuration as a deviation 51 in the housing shell 50 can, for example, be used to compensate for a defect according to position 8 of the Fig. 1 be used.

[0117] Fig. 6 shows a schematic sectional view through an electrochemical energy storage cell 100 according to the invention with a wound composite body 60 located inside a housing 70. In the center of the wound composite body 60 is a winding core 10, which is characterized by a deviation 11 in the form of a stepped widening of the outer diameter of the winding core. This winding core 10 corresponds to the Fig. 2 , Partial Figure A, shows the embodiment of the winding core according to the invention. In the area of ​​the deviation 11, one end of an electrode strip can be applied to the step present in the outer circumferential surface. This prevents the formation of an edge and the resulting irregularities in the spiral structure.

[0118] Overall, the energy storage cell according to the invention is characterized by a more uniform winding of the wound composite body. This has a positive effect on the winding quality and leads to a minimization of failures, particularly as a result of conventionally occurring edges, which are eliminated in the energy storage cell according to the invention. Furthermore, the manufacturing process of the energy storage cell and the winding process can be optimized in the manner described. Furthermore, with the energy storage cell according to the invention, it is in principle possible to utilize more free volume in the energy storage cell, which additionally creates potential for increasing capacity.

[0119] Fig. 7shows a further example of how the local deviation 71 from the hollow cylindrical shape of the housing shell 70 can be realized. For this purpose, the housing shell 70 can be reinforced by a band-shaped insert 75, which rests against the inside of the housing shell 70 over its entire length, but cannot completely cover the inside because it is shorter than the inner circumference of the housing shell 70. The inner diameter is wider in the section 76, in which the band-shaped insert 75 does not cover the inside, compared to all other sections.

Claims

1. Electrochemical energy storage cell (100) having the features a. the energy storage cell (100) has a cylindrical housing which encloses an interior and has a top side and an underside and a circumferential housing casing (50; 70) in between, b. the housing casing (50; 70) has an inner housing lateral surface which delimits the interior to the outside, c. a wound composite body (60) shaped in a hollow cylindrical manner is arranged in the interior and has a helical structure comprising at least two electrode strips helically wound around a winding axis and at least one separator strip arranged between the electrode strips, d. the electrode strips each comprise a strip-like current collector having an active material coating on both sides, e. the wound composite body (60) shaped in a hollow cylindrical manner comprises two terminal end faces, a circumferential outer composite body lateral surface and a circumferential inner composite body lateral surface, f. the inner composite body lateral surface defines an axially oriented cavity in the centre of the wound composite body (60), and g. a winding core (10; 20; 30) having a substantially cylindrical or hollow cylindrical shape is arranged in the axially oriented cavity and has an outer circumferential surface which rests flat on the inner composite body lateral surface, and the characterizing features h. the winding core (10; 20; 30) has a local deviation (11; 21; 31) from the cylindrical or hollow cylindrical shape in at least one region of the outer circumferential surface, i. the helical structure of the wound composite body comprises at least one local irregularity in at least one region in which one of the wound electrode strips ends and / or there is a sudden change in the thickness of one of the electrode strips, and j. the at least one region of the outer circumferential surface of the winding core (10; 20; 30) in which the local deviation (11; 21; 31) from the cylindrical or hollow cylindrical shape occurs is spatially assigned to a local irregularity of the wound composite body (60).

2. Electrochemical energy storage cell (100) according to Claim 1 having at least one of the following additional features: a. The local deviation (11; 21) from the cylindrical or hollow cylindrical shape involves a stepped or continuous reduction and / or expansion of the outer diameter of the winding core. b. The local deviation (11; 21) involves at least one stepped or continuous reduction and / or expansion of the outer diameter of the winding core, wherein the at least one stepped or continuous reduction and / or expansion of the outer diameter extends axially over preferably the entire height of the winding core.

3. Electrochemical energy storage cell (100) according to either of the preceding claims having at least one of the following additional features: a. The local deviation (21) in the at least one region of the outer circumferential surface of the winding core (20) involves a depression in the outer circumferential surface of the winding core and / or a curvature of the outer circumferential surface of the winding core. b. The local deviation (21) in at least one region of the outer circumferential surface of the winding core (20) involves a depression in the outer circumferential surface of the winding core and / or a curvature of the outer circumferential surface of the winding core, wherein the depression and / or the curvature extend(s) axially over preferably the entire height of the winding core.

4. Electrochemical energy storage cell (100) according to any of the preceding claims having at least one of the following additional features: a. The winding core (10; 20) is in the form of a hollow cylinder and has an inner core lateral surface which delimits an axially oriented cavity in the interior of the winding core. b. The winding core (10; 20) has, as a local deviation, a depression in the outer circumferential surface and a corresponding curvature projecting into the axially oriented cavity. c. The winding core (10; 20) has, as a local deviation, a curvature of the outer circumferential surface and a corresponding depression in the inner core lateral surface.

5. Electrochemical energy storage cell (100) according to any of the preceding claims having the following additional feature: a. The local deviation (31) in the at least one region of the outer circumferential surface of the winding core (30) in the form of a hollow cylinder comprises an aperture in the wall of the winding core, in particular a slot in the wall.

6. Electrochemical energy storage cell (100) according to any of the preceding claims having at least one of the following additional features: a. The outer circumferential surface of the winding core (10; 20; 30) has one or more depressions for accommodating at least one sensor. b. The outer circumferential surface of the winding core (10; 20; 30) has one or more depressions for accommodating at least one sensor, wherein the depression(s) extend(s) axially over preferably the entire height of the winding core.

7. Electrochemical energy storage cell (100) according to any of the preceding claims having at least one of the following additional features: a. The housing casing has a hollow cylindrical shape. b. The housing casing has a local deviation (51) from the hollow cylindrical shape in at least one region of its inner housing lateral surface.

8. Electrochemical energy storage cell (100) according to Claim 7 having the following additional feature: a. The at least one region of the inner housing lateral surface which has the local deviation (51) is spatially assigned to a local defect of the wound composite body (60).

9. Electrochemical energy storage cell (100) according to Claim 7 or Claim 8 having at least one of the following additional features: a. The local deviation (51) involves a stepped or continuous reduction and / or expansion of the inner diameter of the housing casing. b. The local deviation (51) involves a stepped or continuous reduction and / or expansion of the inner diameter of the housing casing, wherein the stepped or continuous reduction and / or expansion of the inner diameter extend(s) axially over preferably the entire height of the housing. c. The local deviation (51) involves a depression (53) in the inner housing lateral surface and / or a curvature (52) of the inner housing lateral surface. d. The local deviation (51) involves a depression (53) in the inner housing lateral surface and / or a curvature (52) of the inner housing lateral surface, wherein the depression and / or curvature extend(s) axially over preferably the entire height of the housing.

10. Electrochemical energy storage cell (100) according to any of the preceding claims having one of the following additional features: a. The electrochemical energy storage cell is a cylindrical round cell, or b. the electrochemical energy storage cell is a button cell.

11. Method for producing an electrochemical energy storage cell according to any of features 1 to 10 having the following method steps: a. At least two electrodes strips each having a strip-like current collector with an active material coating on both sides and at least one separator strip arranged between the electrode strips are provided. b. A winding core (10; 20; 30) having a substantially cylindrical or hollow cylindrical shape is provided and has an outer circumferential surface, wherein the outer circumferential surface of the winding core has a deviation (11; 21; 31) from a cylindrical or hollow cylindrical shape in at least one region. c. In order to produce a wound composite body (60), the electrode strips and the at least one separator strip are helically wound around the winding core (10; 20; 30) so as to form a helical structure, wherein the winding is carried out in such a manner that the deviation (11; 21; 31) is spatially assigned to a local defect in the helical structure. d. A cylindrical housing (70) for the energy storage cell is provided. e. The wound composite body (60) is introduced into the housing (70), f. Electrical contact is made with the wound composite body (60) and the housing (70) is closed.