Energy storage element and battery

Abstract

A secondary energy storage element (100) comprises, as electrodes, a cathode (108) and an anode (105), which are part of a composite body (104) in which they are provided, separated by a separator layer or solid electrolyte layer (116), in the sequence cathode (108) / separator layer or solid electrode layer (116) / anode (105). The cathode (108) comprises a cathode current collector (109) and a positive electrode material (110), the anode (105) comprises an anode current collector (106) and a negative electrode material (107). The cathode current collector (109) has a main region which is charged on both sides with a layer consisting of the positive electrode material (110), and has a free edge strip (109b) which extends along an edge of the cathode current collector (109) and is not charged with the positive electrode material (110). Alternatively or simultaneously, the anode current collector (106) has a main region which is charged on both sides with a layer consisting of the negative electrode material (107), and has a free edge strip (106b) which extends along an edge of the anode current collector (106) and is not charged with the negative electrode material (107). The cathode (108) and the anode (105) are designed and / or arranged with respect to one another within the composite body (104) such that the free edge strip (109b) of the cathode current collector (109) emerges from one side (104b) of the composite body (104) and / or the free edge strip (106b) of the anode current collector (106) emerges from another side (104a) of the composite body (104). The energy storage element comprises a first contact metal sheet (112) which is in direct contact with one of the free edge strips (106b) and / or a second contact metal sheet (109a) which is in direct contact with the other of the free edge strips (109b). The electrodes (105, 108) comprise at least one ion type from the group comprising sodium ions, potassium ions, calcium ions, magnesium ions and aluminium ions, which are exchanged between the cathode (108) and the anode (105) during charging and discharging of the secondary energy storage element (100).

Description

[0001] Energy storage element and battery

[0002] The invention relates to an energy storage element suitable for providing very high currents, as well as a method for producing such an energy storage element.

[0003] Area of ​​application and state of the art

[0004] Electrochemical energy storage elements are capable of converting stored chemical energy into electrical energy through a redox reaction. One of the simplest forms of an electrochemical energy storage element is the electrochemical cell. It comprises a positive and a negative electrode, separated from each other by a separator, for example. During a discharge, electrons are released at the negative electrode through an oxidation process. This results in an electron current that can be tapped by an external electrical consumer, for which the electrochemical cell serves as an energy supplier. At the same time, an ion current corresponding to the electrode reaction occurs within the cell. This ion current passes through the separator and is usually enabled by an ion-conducting electrolyte.

[0005] If the discharge is reversible, meaning it is possible to reverse the conversion of chemical energy into electrical energy during the discharge and recharge the cell, it is called a secondary cell. The commonly used designation for secondary cells is the anode for the negative electrode and the cathode for the positive electrode, which refers to the discharge function of the electrochemical cell.

[0006] Secondary lithium-ion cells are now used as energy storage elements for many applications because they can deliver high currents and are characterized by a comparatively high energy density. They are based on the use of lithium, which can migrate back and forth between the cell's electrodes in the form of ions. The negative and positive electrodes of a lithium-ion cell are typically formed by so-called composite electrodes, which include both electrochemically active and electrochemically inactive components.

[0007] In principle, any material capable of absorbing and releasing lithium ions can be considered as electrochemically active components (active materials) for secondary lithium-ion cells. Carbon-based particles, such as graphitic carbon, are used for the negative electrode. Lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium iron phosphate (LiFePCU), or derivatives thereof can be used as active materials for the positive electrode. The electrochemically active materials are usually contained in the electrodes in particle form.

[0008] As electrochemically inactive components, the composite electrodes generally comprise a flat and / or strip-shaped current collector, for example, a metallic foil, which serves as a carrier for the respective active material. The current collector for the negative electrode (anode current collector) can be made of copper or nickel, for example, and the current collector for the positive electrode (cathode current collector) can be made of aluminum, for example. Furthermore, the electrodes can comprise an electrode binder (e.g., polyvinylidene fluoride (PVDF) or another polymer, such as carboxymethyl cellulose), conductivity-enhancing additives, and other additives as electrochemically inactive components. The electrode binder ensures the mechanical stability of the electrodes and often also the adhesion of the active material to the current collectors.

[0009] Lithium-ion cells typically contain electrolytes consisting of solutions of lithium salts such as lithium hexafluorophosphate (LiPF6) in organic solvents (e.g. ethers and esters of carbonic acid).

[0010] During the production of a lithium-ion cell, the composite electrodes are combined with one or more separators to form a composite body. The electrodes and separators are usually combined under pressure, possibly by lamination or bonding. The basic functionality of the cell can then be achieved by impregnating the composite with the electrolyte.

[0011] In many embodiments, the composite body is formed in the form of a coil or processed into a coil. Alternatively, the composite body can also be a stack of electrodes.

[0012] Analogous to lithium-ion cells, sodium-ion cells, which use the alkali metal sodium in the form of sodium ions, potassium-ion cells, which use the alkali metal potassium in the form of potassium ions, calcium-ion cells, which use the alkaline earth metal calcium in the form of calcium ions, magnesium-ion cells, which use the alkaline earth metal magnesium in the form of magnesium ions, and aluminum-ion cells, which use aluminum in the form of aluminum ions, can also be manufactured. The structure of the composite electrodes and their further processing can essentially be adopted 1:1 for cells with these alternative cell chemistries, with current collector materials, electrode materials, electrolytes, and separators tailored to the respective cell chemistry being used.

[0013] Sodium-ion cells, in particular, have now reached practical use. Unlike lithium-ion technology, the production of sodium-ion cells is not limited by scarce resources. However, they have, on average, a lower energy density than lithium-ion cells.

[0014] Due to their high energy density, lithium-ion cells are particularly suitable as an energy source for electric motors in the automotive sector, but also for e-bikes and other applications with high energy requirements, such as power tools. This requires lithium-ion cells that are optimized to withstand high currents during charging and discharging.

[0015] Traditionally, the electrodes, particularly those of wound composites, are contacted via metal strips (tabs) that are welded to the current collectors and protrude from the front of the wound composites, as shown, for example, in Figures 1 and 2 of US 2005 / 0277019 A1. This can be disadvantageous when high currents occur. Both the tabs mentioned and the electrochemically active components of conventional lithium-ion cells have limited high-current capability, particularly in the charging direction and at low temperatures (< 10 °C). Both electrical and thermal gradients occur. The tabs also impair wound composites mechanically, which can lead to unfavorable pressure conditions.

[0016] WO 2017 / 215900 A1 discloses cylindrical lithium-ion cells in which a composite body is formed from strip-shaped electrodes and is in the form of a coil. The electrodes each have current collectors loaded with electrode material. Oppositely polarized electrodes are arranged offset from one another within the composite body, so that longitudinal edges of the current collectors of the positive electrodes emerge from the coil on one side and longitudinal edges of the current collectors of the negative electrodes emerge from another side. To electrically contact the current collectors, the cell has contact plates instead of tabs. These plates sit on the end faces of the coil and are welded to the longitudinal edges of the current collectors. This makes it possible to electrically contact the current collectors and thus also the associated electrodes over their entire length.This significantly reduces the internal resistance within the cell. As a result, large currents can be absorbed much more effectively, and heat can also be dissipated more effectively from the winding.

[0017] Similar cell constructions can be found in EP 3916841 A1 , EP 3916828 A1 , EP 3916827 A1 , EP 3916829 A1 , EP 3916870 A1 , EP 3916869 A1 , EP 3916877 A1 , EP 3965196 A1 and EP 3916868 A1.

[0018] Lithium-ion cells have not yet established themselves on the market as starter batteries for vehicles with combustion engines, as well as for some other specialized applications. Lead-acid batteries, in which the electrodes are made of lead or lead dioxide and the electrolyte is diluted sulfuric acid, are still predominantly used for these applications. Lead-acid batteries can deliver high currents for short periods and perform well even at low temperatures. Furthermore, they are comparatively inexpensive to produce.

[0019] For environmental reasons, however, a replacement is urgently needed, as lead is extremely toxic. Although efficient deposit systems for batteries exist in many countries, the release of lead during lead ore mining and subsequent processing, as well as during lead recycling, is sometimes difficult to prevent.

[0020] Task and solution

[0021] The object of the present invention was to provide energy storage elements which are not inferior to lead-acid batteries in their performance at low temperatures, but are cheaper than lithium-ion cells and can absorb high currents during charging and deliver high currents during discharging.

[0022] This problem is solved by the energy storage element having the features of independent claim 1. The battery having the features of claim 13 also contributes to solving the problem. Preferred embodiments of the invention are defined in the dependent claims.

[0023] Energy storage element according to the invention

[0024] The energy storage element according to the invention always has the directly following features a. to g.: a. It comprises a cathode and an anode as electrodes, which are parts of a composite body in which they are present in the sequence cathode / separator or solid electrolyte layer / anode, separated by a separator or solid electrolyte layer, b. the cathode comprises a cathode current collector and a positive electrode material, c. the anode comprises an anode current collector and a negative electrode material, d.the cathode current collector has a main region which is loaded on both sides with a layer of the positive electrode material, as well as a free edge strip which extends along an edge of the cathode current collector and which is not loaded with the positive electrode material, and / or the anode current collector has a main region which is loaded on both sides with a layer of the negative electrode material, as well as a free edge strip which extends along an edge of the anode current collector and which is not loaded with the negative electrode material, e. the cathode and the anode are designed and / or arranged relative to one another within the composite body such that the free edge strip of the cathode current collector emerges from one side of the composite body and / or the free edge strip of the anode current collector emerges from another side of the composite body, and f.the energy storage element comprises a first contact metal sheet in direct contact with one of the free edge strips and / or a second contact metal sheet in direct contact with the other of the free edge strips, wherein g. the electrodes comprise at least one ion type from the group consisting of sodium ions, potassium ions, calcium ions, magnesium ions, and aluminum ions, which are exchanged between the cathode and the anode during charging and discharging of the secondary energy storage element. Thus, in its simplest embodiment, the energy storage element according to the invention is a sodium ion cell, a potassium ion cell, a calcium ion cell, a magnesium ion cell, or an aluminum ion cell. Among these variants, energy storage elements with sodium ion cell chemistry are particularly preferred according to the invention.

[0025] When very high currents and / or low temperatures occur, it is essential to minimize any electrical, thermal, and ionic gradients in all electrochemically active components of a cell. Avoiding electrical losses plays a crucial role. The lowest possible gradients across the entire composite body, including the electrolyte compartment, are crucial for service life and current-carrying capacity.

[0026] The first and / or second contact metal sheet ensures a homogeneous electrical and thermal connection of the electrodes of the composite body, in the case of a wound composite body, across their entire length, thus improving performance and increasing service life. The contact metal sheet eliminates the need for tabs for electrode contact. Accordingly, no mechanical disturbances occur within wound composite bodies, which can lead to problems under thermomechanical stress.

[0027] Surprisingly, it has been found that the construction of the energy storage element according to the invention enables a particularly efficient connection of the electrodes, particularly for the Na-ion system (but also for the other post-lithium systems such as the aforementioned systems based on sodium ions, potassium ions, calcium ions, magnesium ions, and aluminum ions). High-performance Na-ion materials can thus be charged and discharged at a rate of up to 100 °C. Furthermore, sodium-ion systems in particular can also be constructed to be resistant to deep discharges.

[0028] Energy storage element with wound composite body

[0029] The composite body of the energy storage element according to the invention can be designed as a coil or as a stack of electrodes. In the wound variant it has the directly following features a. to e.: a. the electrodes and the current collectors as well as the layers made of electrode materials are strip-shaped, b. it comprises at least one strip-shaped separator or at least one strip-shaped solid electrolyte layer, c. the composite body is in the form of a coil in which the electrodes and the at least one separator are wound around a winding axis, wherein the composite body comprises a first and a second terminal end face and a winding jacket and the free edge strip of the cathode current collector emerges from the first end face and / or the free edge strip of the anode current collector emerges from the second end face, d.It comprises a housing, in particular a metal housing, comprising a housing shell or side walls and a base and a cover on the end faces, and e. In the housing, the composite body designed as a coil is aligned such that the coil jacket rests against the inside of the housing shell or the side walls.

[0030] The band-shaped separator forms the separator layer in the composite body.

[0031] In this embodiment, the composite body preferably comprises one band-shaped separator or two band-shaped separators, each having a first and a second longitudinal edge and two end pieces.

[0032] Particularly preferably, the coil and the housing are cylindrical. The housing then preferably has a circumferential housing shell and a circular base and cover. The composite body, designed as a cylindrical coil, is preferably axially aligned in the cylindrical housing.

[0033] Preferably, the electrodes and the at least one separator are wound spirally around the winding axis.

[0034] Symmetrical and asymmetrical winding contact

[0035] The composite body in the form of the winding can be contacted both symmetrically and asymmetrically.

[0036] Symmetrical contacting means that the cathode and the anode of the energy storage element are designed and / or arranged relative to one another within the composite body in such a way that the free edge strip of the cathode current collector emerges from one of the end faces of the composite body and the free edge strip of the anode current collector emerges from the other of the end faces of the composite body, and the energy storage element comprises a first contact metal sheet which is in direct contact with one of the free edge strips and a second contact metal sheet which is in direct contact with the other of the free edge strips.

[0037] Both electrodes are thus contacted via contact metal sheets on the two end faces of the coil.

[0038] Asymmetric contacting means that the cathode and the anode of the energy storage element are designed and / or arranged relative to one another within the composite body in such a way that either only the free edge strip of the cathode current collector or only the free edge strip of the anode current collector emerges from one of the end faces of the composite body, and the energy storage element comprises only one contact metal sheet which is in direct contact with the free edge strip of the cathode current collector or the anode current collector emerging from the composite body.

[0039] In this embodiment, only one of the electrodes is contacted via a contact metal sheet at one of the two end faces of the composite body. Preferably, at least one metallic conductor strip (tab) is attached to the current collector of the other electrode, which extends from the other of the terminal end faces of the composite body.

[0040] In the case of asymmetric contact, the energy storage element according to the invention is characterized by one of the directly following features a. to c.: a. The at least one metallic conductor strip is connected by welding to the cover or to a metallic pole guided through the cover, while the free edge strip emerging from one of the end faces is welded to the base or to a metal sheet sitting directly on the base of the housing (variant A), or b. the at least one metallic conductor strip is welded to the base, while the free edge strip emerging from one of the end faces is connected by welding to the cover or to a pole guided through the cover (variant B). or c.the at least one metallic conductor strip is welded to the base, while the free edge strip emerging from one of the end faces is connected by welding to a pole guided through the cover or to a metal sheet resting on the free edge strip, which is electrically coupled to the cover or the pole (variant C).

[0041] In variant B, the bottom of the housing acts as a contact metal sheet, which can be particularly advantageous since this design allows optimal heat dissipation of the electrode coupled via the free edge strip.

[0042] It is particularly advantageous if the anode current collector is connected directly to the base according to variant B, while the cathode current collector is connected via the tab. The use of the arrester strip on the end face of the winding facing the cover, with simultaneous connection of the anode over the ideally entire longitudinal edge of its current collector, can offer volumetric advantages, which are particularly important for energy-optimized cells. At the same time, positive effects result from the excellent connection of the anode and thus improved performance and service life of the cell according to the invention. The most homogeneous electrical and thermal connection of the anode is particularly advantageous for improved rapid charging capability. It should be specifically mentioned in this context that sodium-ion electrolytes generally have higher conductivities than their lithium counterparts and therefore have advantages in terms of thickness and / orhighly charged electrodes, fast charging (> 2 °C) and performance at low temperatures (< 0 °C) come into play.

[0043] Preferred developments of the energy storage element with wound composite body

[0044] In energy storage elements with a wound composite body, the contact metal sheet(s) preferably lie flat on one or both end faces, preferably in such a way that the free edge strip(s) are in contact with the contact metal sheet(s) over their entire length. In practice, however, this is often not achievable.

[0045] Particularly preferably, the energy storage element according to the invention with a wound composite body is characterized by the immediately following feature a.: a. The metal housing comprises a cup-shaped, cylindrical housing part with a terminal, preferably circular, opening and a cover which closes the terminal opening of the cup-shaped housing part.

[0046] In many preferred embodiments, the lid is a lid component consisting of several components. For example, the lid can comprise a bursting membrane and / or be equipped with a CID function (CID = Current Interrupt Device).

[0047] The cover preferably has a circular circumference and is arranged in the circular opening of the cup-shaped housing part such that the edge rests against the inside of the cup-shaped housing part along a circumferential contact zone, with the edge of the cover being connected to the cup-shaped housing part via a circumferential weld seam. In this case, the two housing parts preferably have the same polarity, i.e., are electrically coupled to either a positive or a negative electrode. In this case, the housing also comprises a terminal feedthrough, which serves to electrically contact the electrode not electrically connected to the housing.

[0048] In an alternative embodiment, an electrically insulating seal is applied to the edge of the lid, electrically separating the lid from the cup-shaped housing part. In this case, the housing is usually sealed with a crimp closure.

[0049] The height of energy storage elements configured as cylindrical round cells is preferably in the range of 50 mm to 150 mm. The diameter of the cylindrical round cells is preferably in the range of 15 mm to 100 mm.

[0050] The anode current collector, the cathode current collector and the separator or separators or the solid electrolyte layer in embodiments in which the energy storage element according to the invention is a cylindrical round cell preferably have the following dimensions: A length in the range of 0.3 m to 25 m

[0051] A width in the range 30 mm to 145 mm

[0052] In this embodiment, the contact metal sheets preferably have a circular basic shape.

[0053] Prismatic design

[0054] In the prismatic embodiment, the energy storage element according to the invention is characterized by the immediately following features a. to c., particularly preferably by the immediately following features a. to d.: a. The composite body is in the form of a prismatic stack in which the cathode and the anode are stacked together with other cathodes and anodes. b. The electrodes and the current collectors as well as the layers made of the electrode materials are polygonal, in particular rectangular. c. It comprises at least one strip-shaped or polygonal, in particular rectangular, separator or at least one strip-shaped or polygonal, in particular rectangular, solid electrolyte, d. The stack is enclosed by a prismatic housing.

[0055] In the stack, adjacent oppositely polarized electrodes are always separated from each other by a separator or solid electrolyte layer.

[0056] The prismatic housing preferably consists of a cup-shaped housing part with an end opening and a lid. In this embodiment, the base of the cup-shaped housing part and the lid preferably have a polygonal, particularly preferably a rectangular, base area. The shape of the end opening of the cup-shaped housing part corresponds to the shape of the base and the lid. Furthermore, the housing comprises several, preferably four, rectangular side parts that connect the base and the lid.

[0057] Prismatic-shaped cells can also be constructed as so-called pouch cells. Instead of the metallic housing components, composite foils are used, which are formed into the required shape using a deep-drawing process. The current conductors are routed to the outside via the areas where the composite foils are thermally welded / sealed.

[0058] The separator layers can be formed by multiple separators, each arranged between adjacent electrodes. However, it is also possible for a strip-shaped separator to separate the electrodes of the stack from each other. In the case of multiple separators between the anodes and cathodes, the separators preferably also have a polygonal, particularly rectangular, base area.

[0059] In this embodiment, the contact metal sheets preferably have a rectangular basic shape.

[0060] In some preferred variants of the prismatic embodiment, the energy storage element according to the invention is characterized by at least one of the immediately following features a. and b.: a. The free edge strips of the cathode current collectors of the cathodes of the stack emerge from one side of the stack and are in direct contact with the first contact metal sheet. b. The free edge strips of the anode current collectors of the anodes of the stack emerge from another side of the stack and are in direct contact with the second contact metal sheet.

[0061] Preferably, the immediately above features a. and b. are implemented in combination with one another.

[0062] In further preferred variants of the prismatic embodiment, the energy storage element according to the invention is characterized by at least one of the immediately following features a. and b.: a. The free edge strips of the cathode current collectors are arranged parallel to one another. b. The free edge strips of the anode current collectors are arranged parallel to one another.

[0063] Preferably, the immediately above features a. and b. are implemented in combination with one another.

[0064] Preferred electrochemical embodiment and electrolyte

[0065] In another particularly preferred embodiment of the invention, the energy storage element according to the invention is characterized by one of the following features: a. The energy storage element is a sodium-ion cell. b. The energy storage element comprises a sodium-ion cell. c. The energy storage element comprises one of the following electrolytes:

[0066] NaCIO4 dissolved in at least one organic solvent, in particular in PC or in a carbonate mixture from the group containing EC / DEC / FEC and PC / FEC.

[0067] The concentration of NaCIO4 in the electrolyte is preferably 0.3 - 5 M, particularly preferably 0.7 M - 1.7 M.

[0068] In an EC / DEC / FEC mixture, the three components are preferably contained in the electrolyte in a volume ratio in the range of 1:2 to 2:1, in particular 1:1:0.5.

[0069] In the case of a mixture comprising EC / DEC, the components are preferably contained in the electrolyte in a volume ratio in the range of 1:2 to 2:1.

[0070] NaPF6 and / or NaTFSI (sodium bis(trifluoromethanesulfonyl)imide) dissolved in at least one organic solvent, in particular in PC or in a carbonate mixture from the group consisting of EC / DEC / FEC, EC / PC, EC / DEC, FEC / EMC and PC / FEC or in an ether mixture such as THF / mTHF.

[0071] The concentration of NaPF6 and / or NaTFSI in the electrolyte is preferably 0.3 - 5 M, particularly preferably 0.7 M - 1.7 M.

[0072] In an EC / PC mixture, the two components are preferably contained in the electrolyte in a volume ratio in the range of 1:2 to 2:1.

[0073] In an EC / DEC mixture, the two components are preferably contained in the electrolyte in a volume ratio ranging from 1:2 to 2:1. In an FEC / EMC mixture, the two components are preferably contained in the electrolyte in a volume ratio ranging from 1:2 to 2:1, in particular in a ratio of 3:7.

[0074] If necessary, the electrolyte may contain an additive of up to 10% FEC.

[0075] NaFSI and / or NaTFSI and / or NaTDI dissolved in at least one organic solvent, in particular in 1,4-dioxane (DX) and / or 1,3-dioxolane (DOL) and / or dimethyl ether (DME).

[0076] The concentration of NaFSI and / or NaTFSI and / or NaTDI in the electrolyte is preferably 0.3 - 5 M, particularly preferably 0.7 M - 1.7 M.

[0077] NaFSI and / or NaTFSI and / or NaTDI dissolved in at least one organic solvent, in particular in dimethyl carbonate (DX) and / or tris(2,2,2-trifluoroethyl)phosphate (TFP).

[0078] The concentration of the NaFSI and / or the NaTFSI and / or the NaTDI in the electrolyte is preferably 0.5 - 2.5 M, particularly preferably 1 M - 2 M.

[0079] In an EC / PC mixture, the components are preferably contained in the electrolyte in a volume ratio in the range of 1:2 to 2:1.

[0080] Particularly preferably, the liquid components are contained in the electrolyte in a volume ratio in the range of 1:2 to 2:1.

[0081] NaN(SO2F)2dissolved in at least one organic solvent, in particular in 1,4-dioxane (DX) and / or 1,3-dioxolane (DOL) and / or dimethyl ether (DME).

[0082] The concentration of NaN(SO2F)2 in the electrolyte is preferably 0.3 - 5 M, particularly preferably 0.7 M - 1.7 M.

[0083] In a DX / DOL mixture, the components are preferably contained in the electrolyte in a volume ratio in the range of 1:2 to 2:1.

[0084] NaBF4 dissolved in at least one organic solvent, in particular in tetraethylene glycol dimethyl ether (TEGDME) and / or in ACN and / or in PC and / or GBL. The concentration of NaBF4 in the electrolyte is preferably 0.3-5 M, particularly preferably 0.7 M-1.7 M.

[0085] An electrolyte with NaBF4in TEGDME is particularly suitable for cells with Na metal anode (see below).

[0086] Particularly preferably, features a. and c. as well as b. and c. are implemented in combination with one another.

[0087] Feature a. relates in particular to the described embodiment of the energy storage element according to the invention as a cylindrical round cell. In this embodiment, the energy storage element preferably comprises precisely one electrochemical cell.

[0088] Feature b. relates in particular to the described prismatic embodiment of the energy storage element according to the invention. In this embodiment, the energy storage element can also comprise more than one electrochemical cell.

[0089] Preferably, the energy storage element according to the invention based on sodium ions further comprises an electrolyte which comprises at least one of the following solvents and at least one of the following conductive salts:

[0090] Preferred solvents are:

[0091] Carbonate: Propylencarbonat (PC), Ethylencarbonat-Propylencarbonat (EC-PC), Pro- pylencarbonat-Dimethylcarbonat-Ethylmethylcarbonat (PC-DMC-EMC), Ethylencarbo- nat-Diethylcarbonat (EC-DEC), Ethylencarbonat-Dimethylcarbonat (EC-DMC), Ethy- lencarbonat-Ethylmethylcarbonat (EC-EMC), Ethylencarbonat-Dimethylcarbonat- Ethylmethylcarbonat (EC-DMC-EMC), Ethylencarbonat-Dimethylcarbonat-Diethylcar- bonat (EC-DMC-DEC)

[0092] Ether: Tetrahydrofuran (THE), 2-Methyltetrahydrofuran, Dimethylether (DME), 1 ,4-di- oxane (DX), 1 ,3-dioxolane (DOL), Diethylenglykoldimethylether (DEGDME), Tetraethylenglykoldimethylether (TEGDME)

[0093] Nitrile: Acetonitril (ACN), Adiponitril (AON), y-Butyrolactone (GBL)

[0094] Weiterhin kommen auch Trimethylphosphat (TMP) und Tris(2,2,2-trifluoroethyl)phosphat (TFP) in Frage. Bevorzugte Leitsalze sind:

[0095] NaPF6, sodium difluoro(oxalato)borate (NaBOB), NaBF4, sodium bis(fluorosulfonyl)imide (NaFSI), sodium 2-trifluoromethyl-4,5-dicyanoimidazole (NaTDI), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), NaAsF6, NaBF4, NaCIO4, NaB(C2O4)2, NaP(C6H4O2)3; NaCF3SO3, sodium triflate (NaTf) and Et4NBF4.

[0096] Like the solvents, the conducting salts can also be used as a mixture of two or more conducting salts.

[0097] In preferred embodiments, additives can be added to the electrolyte. Examples of preferred additives, particularly for stabilization, are the following:

[0098] Fluoroethylene carbonate (FEC), transdifluoroethylene carbonate (DFEC), ethylene sulfite (ES), vinylene carbonate (VC), bis(2,2,2-trifluoroethyl)ether (BTFE), sodium 2-trifluoromethyl-4,5-dicyanoimidazole (NaTDI), sodium bis(fluorosulfonyl)imide (NaFSI), aluminum chloride (AICI3), ethylene sulfate (DTD), sodium difluorophosphate (NaPO2F2), sodium difluoro(oxalato)borate (NaODFB), sodium difluorobisoxalatophosphate (NaDFOP) and tris(trimethylsilyl)borate (TMSB).

[0099] Instead of liquid electrolytes with the aforementioned conducting salts, ionic liquids can also be used, e.g. 0.8 mol / l sodium bis(fluorosulfonyl)imide (Na-TFSI) in 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PMPyrr-TFSI).

[0100] Sodium polymer electrolytes can also be used as an alternative, for example polymer electrolytes based on polyethylene oxide (PEO) or on polyvinylidene difluoride-cohexafluoropropylene, such as P(EO)8NaCF3SO3 or hydroxyethylcellulose-polyethylene oxide.

[0101] Instead of liquid electrolytes based on organic solvents, aqueous sodium electrolytes with anions from the group of SO4, NO3-, Cl' and SO4 can also be used in special applications. 2 ' or aqueous solutions of NaFSI, NaTDI or NaTFSI.

[0102] Preferred embodiments of the electrode materials

[0103] The negative electrode material of an energy storage element according to the invention based on sodium ions is preferably at least one of the following materials:

[0104] Carbon, especially preferred hard carbon (pure or with nitrogen and / or phosphorus doping) or soft carbon or graphene-based materials (with N-doping); carbon nanotubes, graphite

[0105] Phosphorus or sulfur (conversion anode)

[0106] Polyanions: Na2Ti3O7, Na3Ti2(PO4)3, TiP2O7, TiNb2O7, Na-Ti-(PO4)3, Na-V-(PO4)3 or Na-M-PO4-P2O7 with M = V, Ti, Fe, Co, Ni, Mn, or mixtures of 3d transition metals and added doping elements such as Al, Cu, Zn

[0107] Na4M3(PO4)2(P2O7) with M= Na, Zn, Al, Mg, or Ca

[0108] Sn- or Sb-based materials such as Sn(Na 15 Sn4), Sb(Na3Sb), SnO2, Sb2O3

[0109] Prussian Blue: Low-Na variant (for systems with aqueous electrolyte)

[0110] Transition metal oxides: V2O5, MnO2, TiO2, Nb2O5, Fe2O3, Na2Ti3O7, NaCrTiO4, Na4Ti5O 12

[0111] MXenes with M= Ti, V, Cr, Mo or Nb and A = Al, Si, and Ga and X= C and / or N, e.g. Ti3C2

[0112] Organic: e.g. Na terephthalates (Na2C8H2O4)

[0113] An exemplary overview of suitable anode materials can also be found in the publication by Zhang et al., "SODIUM-ION BATTERY ANODES: STATUS AND FUTURE TRENDS", EnergyChem 1 , 100012 (2019) from 2019 in Table 2 on page 19.

[0114] Alternatively, a sodium metal anode can also be used on the anode side. The metallic sodium is preferably embedded in a porous, electrically conductive matrix structure with good sodium wettability. Minimal electrical, thermal, and mechanical gradients are of great importance here, which are made possible in the cell according to the invention by the design with end-face contacting of the electrode coil.

[0115] The positive electrode material of an energy storage element according to the invention based on sodium ions is preferably at least one of the following materials:

[0116] Polyanions: NaFePO4(triphylite type), Na2Fe-(P2O7), Na4Fe3(PO4)2(P2O7), Na2FePO4F, Na / Na2[Fei / 2Mn-i / 2]PO4F, Na3 2(PO4)2F3, Na3V2(PO4)3, Na4(CoM- nNi)3(PO4)2P2O7, NaCoPO4, Na2CoPO4F

[0117] Silicates: Na2MnSiO4, Na2FeSiO4

[0118] Prussian Blue I White: Prussian Blue (PB) exists in the form of A x Fe[Fe(CN)6]1. y*nH2O with A = alkali metal and 0 < x < 2 and y < 1 ; Prussian white (Na ~ 2) in the form of Na2Fe[Fe(CN)6], KFe2(CN)6, MnFe(CN)6 and Fe2(CN)6

[0119] Layered oxides: NaCoO2, NaFeO2, NaNiO2, NaCrO2, NaVO2, NaTiO2, Na(FeCo)O2, Na(NiFeCo)3O2, Na(NiFeMn)O2, and Na(NiFeCoMn)O2, Na(NiMnCo)O2

[0120] Blends of the above-mentioned positive electrode materials can also be used.

[0121] In addition, the electrodes of an energy storage element according to the invention preferably contain an electrode binder and / or an additive to improve electrical conductivity. The active materials are preferably embedded in a matrix composed of the electrode binder, with the active materials preferably being used in particulate form and neighboring particles in the matrix preferably being in direct contact with one another. Conductive agents serve to increase the electrical conductivity of the electrodes. Common electrode binders are based, for example, on polyvinylidene fluoride (PVDF), (Na) polyacrylate, styrene-butadiene rubber, (Na) alginate, or carboxymethyl cellulose, or mixtures of different binders. Common conductive agents include carbon black, fine graphite, carbon fibers, carbon nanotubes, and metal powder.

[0122] The following material combinations are particularly preferred for sodium ion-based energy storage elements

[0123] Positive electrode: Na 3 2 (PO4)3

[0124] Negative electrode: Hard Carbon

[0125] Electrolyte: Preferably NaPF6in EC:PC:DMC (45:45:10 Vol%)

[0126] Positive electrode: Na2 / 3(Ni1 / 3Mn2 / 3)O2

[0127] Negative electrode: Hard Carbon

[0128] Positive electrode: Na2Fe[Fe(CN)6]

[0129] Negative Electrode: Hard Carbon Electrolyte: Preferably NaPF6in EC:PC ion depot

[0130] The function of a sodium, potassium, calcium, magnesium or aluminum ion cell is based on the availability of sufficient mobile ions (in the case of a sodium ion cell, for example, mobile sodium ions) to balance the tapped electrical current by migrating between the anode and the cathode or the negative electrode and the positive electrode. In the context of this application, mobile ions are understood to mean that the ions are available for storage and removal processes in the electrodes during the discharge and charge processes of the energy storage element according to the invention or can be activated for this purpose. In the course of the discharge and charge processes, e.g. of a sodium ion cell, losses of mobile sodium occur over time. These losses occur as a result of various, generally unavoidable side reactions.Losses of mobile sodium occur during the first charge and discharge cycle of a sodium-ion cell. During this first charge and discharge cycle, a capping layer typically forms on the surface of the electrochemically active components at the negative electrode. This capping layer is called the Solid Electrolyte Interphase (SEI) and typically consists primarily of electrolyte decomposition products and a certain amount of sodium tightly bound in this layer.

[0131] To compensate for these losses, the sodium-ion-based energy storage element according to the invention, in preferred embodiments, is characterized by at least one of the following features a. and b.: a. The energy storage element comprises a depot of sodium or a sodium-containing material, not encompassed by the positive and / or negative electrode, with which losses of mobile sodium can be compensated during operation. b. The depot is in contact with the electrolyte of the energy storage element.

[0132] It is particularly preferred that the immediately above features a. and b. are implemented in combination with one another.

[0133] Particularly suitable sodium-containing materials include Na3N, Na2C2O4, Na2S, Na2C4O4, Na2C6O6, EDTA-4Na, DPTA-5Na, Na3P, or Ci2H9Na (sodium biphenyl). These materials can be added, for example, to the electrode active material. An additional sodium source leads to higher capacity and longer cycle life.

[0134] It is also conceivable that the electrodes are precharged with an excess of sodium ions.

[0135] The same applies to embodiments of the energy storage element according to the invention based on potassium, calcium, magnesium or aluminum ions.

[0136] Preferred embodiment of a sodium metal anode

[0137] As mentioned above, a Na-metal anode can also be used on the anode side, in which the metallic sodium is preferably embedded in an electrically conductive matrix structure.

[0138] In a further development, it may be preferred that the energy storage element according to the invention is characterized by at least one of the following features: a. The anode comprises a matrix with depressions and / or pores in which metallic sodium is embedded. b. The matrix adheres to the surface of the anode current collector. c. The matrix comprises carbon particles and a binder. d. The matrix comprises conductive agents and / or fillers. e. The matrix is ​​a roughened surface of the anode current collector.

[0139] It is particularly preferred that the immediately above features a. to d. or a. and d. are implemented in combination with one another.

[0140] The carbon particles, conductive agents, or fillers include, for example, hard carbon, activated carbon, conductive graphite, carbon black, carbon nanotubes, graphene or graphene oxide, or finely dispersed metals such as Ag, Cu, Al, Ni, or Pt. For example, the carbon particles can comprise 20-80 wt.% hard carbon and 80-20 wt.% carbon black, as well as 0-10 wt.% silver, with the weight proportions of the components preferably adding up to 100 wt.%. The binder can, in principle, be any binder that is also suitable for the production of composite electrodes for lithium-ion batteries. Suitable examples include polyvinylidene fluoride (PVDF) or another polymer, such as carboxymethylcellulose or a derivative based thereon.

[0141] The carbon-based matrix may comprise doping elements such as boron, oxygen, fluorine or nitrogen.

[0142] The carbon-based matrix is ​​preferably 500 nm to 250 pm thick.

[0143] The surface of the anode current collector can be roughened, for example, by laser treatment.

[0144] Furthermore, it may be preferred that the energy storage element according to the invention is characterized by at least one of the following features: a. The anode comprises, in particular instead of the matrix, a nucleation layer into which metallic sodium is embedded and / or on which metallic sodium is deposited. b. The nucleation layer consists essentially of at least one material from the group consisting of tin, silver, gold, germanium, carbon, platinum, zinc, aluminum, magnesium, and silicon. c. The nucleation layer was deposited on the surface of the anode current collector by means of PVD (physical vapor deposition) or CVD (chemical vapor deposition).

[0145] The nucleation layer of tin, silver, gold, germanium, and / or carbon facilitates the deposition of sodium. Carbon, silver, gold, platinum, zinc, aluminum, magnesium, tin, and silicon reduce the overvoltage.

[0146] The nucleation layer can also contain doping elements, for example boron, oxygen, fluorine or nitrogen.

[0147] The nucleation layer is preferably 100 nm to 50 pm thick.

[0148] It is preferred that the matrix and / or the nucleation layer constitute a proportion of less than 30 wt.%, preferably less than 5 wt.%, of the dry weight of the negative electrode.

[0149] To manufacture an electrode with the matrix or nucleation layer, an anode current collector is preferably provided with the matrix or nucleation layer, but free of metallic sodium. The sodium is preferably deposited in and / or on the matrix or nucleation layer during a first charging process. The required sodium is preferably supplied via the cathode. For example, Na3V2(PO4)3 can be used as the positive electrode material. Alternatively, the sodium deposition can also be carried out by pre-sodium deposition. This procedure prevents dendritic growth and also ensures that no undesirable excess of sodium is present in the electrodes.

[0150] It may be expedient to provide a degassing option during the first charging process so that no excessive pressure builds up in the housing of the energy storage element according to the invention.

[0151] Particularly preferably, a ratio of anode capacity to cathode capacity is set in the range from 0.7 to 1.2.

[0152] The energy storage element according to the invention is particularly preferably characterized by at least one of the following features:

[0153] Particularly preferably, the nucleation layer and / or the matrix are covered with a cover layer. The negative electrode thus preferably comprises the following layer sequence:

[0154] Metallic current collector

[0155] Matrix or nucleation layer

[0156] Top layer

[0157] The matrix or nucleation layer is thus arranged between the cover layer and the current collector.

[0158] The cover layer preferably has a thickness in the range of 300 nm to 30 pm.

[0159] The cover layer is preferably formed from a ceramic material or comprises such a ceramic material. The ceramic material is preferably aluminum oxide (Al2O3), aluminum hydroxide or aluminum oxide hydroxide (AlIOOH), silicon oxide (SiO x with x in the range of >1 and <2), titanium oxide (TiO2), titanium nitride (TiN), titanium aluminum nitride (TiAIN) or titanium carbonitride (TiCN).

[0160] In further possible preferred embodiments, the cover layer is formed from a superion conductor of the chemical formula Na 1+x Zr2Si x P 3-x O 12 (where 0 < x < 3) or comprises such an ion conductor.

[0161] In further possible preferred embodiments, the cover layer is formed from a polymer, in particular a polysiloxane, a polyethylene oxide, a perfluoropolyether or a polyacrylonitrile, or comprises such a polymer.

[0162] If the cover layer comprises the ceramic material, in preferred embodiments it further comprises a binder. This binder can generally be a binder that is also suitable as a binder for the active material, for example, carboxymethylcellulose.

[0163] Preferred embodiments of the separator and the solid electrolyte

[0164] The separator(s) are preferably formed from electrically insulating plastic films. It is preferred that the separators be permeable to the electrolyte. For this purpose, the plastic films used can, for example, have micropores. The film can be made of a polyolefin or a polyether ketone, for example. Nonwovens and woven fabrics made of plastic materials or other electrically insulating sheet-like structures can also be used as separators. Separators with a thickness in the range of 5 μm to 50 μm are preferred.

[0165] Separators made of cellulose-based materials can also be used. These offer good wettability and high temperature stability.

[0166] In particular in the prismatic embodiments of the energy storage element, the separator or separators of the composite may also be one or more layers of a solid electrolyte.

[0167] The solid electrolyte can, for example, be a polymer solid electrolyte based on a polymer-conducting salt complex, which exists in a single phase without any liquid component. A polymer solid electrolyte can contain, for example, polyacrylic acid (PAA), polyethylene glycol (PEG), or polymethyl methacrylate (PMMA), in particular polyethylene oxide (PEO), as a polymer matrix. In the case of a sodium-ion cell, sodium conducting salts such as sodium bis(trifluoromethane)sulfonylimide (NaTFSI), sodium hexafluorophosphate (NaPF6), and sodium tetrafluoroborate (NaBF4) can be dissolved in these.

[0168] Ceramic reinforcement of the separator

[0169] Further preferred embodiments of the separator may be expedient in individual cases. Thus, the energy storage element according to the invention is preferably further characterized by at least one of the immediately following features a. and b.: a. The side of the composite body from which the free edge strip of the cathode current collector or the free edge strip of the anode current collector emerges is formed by an edge of the separator, in the case of an energy storage element with a wound composite body, in particular a longitudinal edge of the separator. b. The edge or longitudinal edge of the separator that forms the side, in particular the end face, is ceramically reinforced.

[0170] In a preferred embodiment, the energy storage element according to the invention is characterized by the immediately following feature a.: a. The ceramic reinforcement is effected by at least one particulate ceramic material, in particular at least one particulate ceramic filler material in the separator.

[0171] The separator can therefore preferably be an electrically insulating plastic film into which the particulate filler material is embedded. It is preferred that the plastic film be permeable to the electrolyte, for example, because it has micropores. The film can be formed, for example, from a polyolefin or a polyether ketone. As mentioned, nonwovens and woven fabrics made of such plastic materials can also be used. These may also be preferred in individual cases.

[0172] The proportion of particulate filler material in the separator is preferably at least 40 wt.%, particularly preferably at least 60 wt.%. In a further preferred embodiment, the energy storage element according to the invention is characterized by the immediately following feature a.: a. The ceramic reinforcement is achieved by at least one particulate ceramic material present as a coating on a surface of the separator(s).

[0173] The separator can therefore preferably also be a plastic film or a fleece or a fabric or another electrically insulating surface structure coated with a ceramic material.

[0174] In some embodiments, only one side of the sheet, in particular the plastic film, is coated with the ceramic material. In further embodiments, the sheet, in particular the plastic film, is preferably coated on both sides with the ceramic material.

[0175] Optionally, it may also be preferred that the separators used comprise a ceramic material as a filler material and the same or a different ceramic material as a coating.

[0176] In further possible preferred developments, the energy storage element according to the invention is characterized by at least one of the immediately following features a. to e.: a. The at least one ceramic material / filler material is or comprises an electrically insulating material. b. The at least one ceramic material / filler material is or comprises at least one material from the group comprising glass-ceramic material and glass. c. The at least one ceramic material / filler material is or comprises a sodium ion-conducting ceramic material, for example Na5AlO4*Na4SiO4 or NaAlSi2O6 or ß-Al2O3 or a NASICON material such as Na3Zr2Si2PO 12 . d. The at least one ceramic material / filler material is or comprises an oxidic material, in particular a metal oxide. e. The ceramic or oxidic material is aluminum oxide (Al2O3), silicon oxide (SiO x), in particular silicon dioxide (SiO2), titanium oxide (TiO2), titanium nitride (TiN), titanium aluminum nitride (TiAIN), a silicon oxide, in particular silicon dioxide (SiO2) or titanium carbonitride (TiCN).

[0177] It is particularly preferred that the immediately preceding features a. to c. or the immediately preceding features a. and b. and d. or the immediately preceding features a. and b. and e. are implemented in combination with one another.

[0178] Among the materials mentioned, aluminum oxide (AI2O3), aluminum hydroxide (AI(OH)3), aluminum oxide hydroxide (AIOOH), titanium oxide (TiO2) and silicon dioxide (SiO2) are particularly preferred as coating materials.

[0179] In further possible preferred developments, the energy storage element according to the invention is characterized by at least one of the immediately following features a. and b.: a. The separator or separators comprise the at least one ceramic material only in certain regions. b. The separator or separators have an edge strip along the edge forming the first side, in particular the first end face, in which they comprise the at least one ceramic material as a coating and / or as particulate filler material.

[0180] It is particularly preferred that the immediately above features a. and b. are implemented in combination with one another.

[0181] It is by no means mandatory that the separator comprise the ceramic material in a homogeneous distribution or be evenly and completely coated with the material. Rather, it may even be preferred that the separator be free of the ceramic material in certain areas, for example, in the aforementioned main area. In this area, increased thermal resistance of the separator is not as necessary as at the edges of the separator. Furthermore, the ceramic material, particularly in this area, can contribute to an undesirable increase in the internal resistance of the energy storage element according to the invention.

[0182] In many embodiments, however, the separator is preferably reinforced or coated with the ceramic material over its entire surface—including between the anode and cathode. The frontal electrode areas without an active material coating could be fully or partially coated with ceramic materials to reduce the risk of short circuits there.

[0183] Further details on coating separators with ceramic materials can be found in WO 2021 / 255238 A1.

[0184] Preferred embodiments of the current collectors

[0185] The current collectors of the electrodes of the energy storage element according to the invention serve to electrically contact electrochemically active components contained in the respective electrode material over as large an area as possible. The current collectors are preferably made of a metal or are at least surface-metallized.

[0186] Particularly in the case of an energy storage element based on sodium ions according to the invention, aluminum or an aluminum alloy are suitable as metallic materials for both the anode current collector and the cathode current collector. Sodium ion systems that have current collectors made of aluminum or an aluminum alloy on both the anode and cathode sides have proven particularly resistant to the effects of deep discharges.

[0187] Suitable aluminum alloys for the cathode current collector include aluminum alloys of type 1235, 1050, 1060, 1070, 3003, 5052, Mg3, Mg212 (3000 series), and GM55. Also suitable are AlSi, AICuTi, AIMgSi, AISiMg, AlSiCu, AI-CuTiMg, and AIMg. The aluminum content of these alloys is preferably above 99.5%.

[0188] Preferably, the anode current collector and / or the cathode current collector are each a strip-shaped metal foil with a thickness in the range of 4 pm to 30 pm.

[0189] In addition to foils, other strip-shaped substrates such as metallic or metallized nonwovens or open-pored metallic foams or expanded metals can also be used as current collectors.

[0190] The current collectors are preferably loaded on both sides with the respective electrode material.

[0191] Edge reinforcement of the current collector(s) The energy storage element according to the invention is preferably further characterized by at least one of the immediately following features a. to c.: a. In the free edge strip of the cathode current collector and / or in the free edge strip of the anode current collector, the surface of the cathode current collector and / or the anode current collector is coated with a support material that is more thermally stable than the surface coated therewith. b. The non-metallic material is a ceramic material, a glass-ceramic material, or a glass. c. The ceramic material is aluminum oxide (Al2O3), aluminum hydroxide (Al(OH)3), aluminum oxide hydroxide (AlOOH), titanium oxide (TiO2), titanium nitride (TiN), titanium aluminum nitride (TiAIN), or titanium carbonitride (TiCN).

[0192] "Thermally more stable" means that the support material remains solid at a temperature at which the surface melts. This means that it either has a higher melting point than the surface, or it sublimates or decomposes only at a temperature at which the surface is already melted.

[0193] Preferably, both the free edge strip of the cathode current collector and the free edge strip of the anode current collector are coated with the support material. Particularly preferably, the same support material is used in each case.

[0194] The contact metal sheets in direct contact with the free edge strip(s) are preferably connected to the edge strips by welding. This can lead to problems, namely accidental depression or melting of the edge strips of the current collectors. The support material counteracts these problems. It mechanically supports the edge strips of the current collectors and prevents melting of the edges, especially if the edge strips are coated on both sides with the support material. Furthermore, the support material also prevents short circuits resulting from the aforementioned melting of separators of the composite body. The support material electrically insulates the free areas covered by it. Thus, in preferred embodiments, it is electrically insulating.

[0195] Further details on suitable support materials can be found in WO 2020 / 239512 A1.

[0196] In particularly preferred embodiments, the support material covers not only the edge strip or part of the edge strip of the anode current collector, but also the electrode material arranged on the anode current collector in the main region. The layer of support material can thus simultaneously function as a cover layer, covering, for example, the matrix described above or the nucleation layer described above. This preferably applies when the support material is one of the aforementioned ceramic materials.

[0197] The support layer can also comprise a binder which, for example, holds ceramic particles of the support layer together.

[0198] Preferred embodiments of the composite body

[0199] To prevent direct contact between oppositely polarized electrodes at the axial ends of a coil or stack, separators are preferably used that are slightly wider than the electrodes to be separated. In an energy storage element with a wound composite body, the composite body thus terminates at each of its axial ends in preferred embodiments with a separator projection, which accordingly forms the end faces.

[0200] In the case of the prismatic configuration described, it is preferred that the edges of the separator(s) form the sides of the stack from which the free edge strips of the current collectors protrude.

[0201] It is further preferred that the free edge strips of the current collectors emerging from the terminal end faces of the coil or sides of the stack do not protrude more than 5500 pm, preferably not more than 4000 pm, from the end faces or sides.

[0202] Particularly preferably, the free edge strip of the anode current collector protrudes from the side of the stack or the end face of the coil by no more than 3000 pm, particularly preferably no more than 2000 pm. Particularly preferably, the free edge strip of the cathode current collector protrudes from the side of the stack or the end face of the coil by no more than 4000 pm, particularly preferably no more than 3000 pm.

[0203] In the composite body formed as a coil, the strip-shaped anode, the strip-shaped cathode, and the strip-shaped separator(s) are preferably wound spirally. To produce the composite body, the strip-shaped electrodes are preferably fed together with the strip-shaped separator(s) to a winding device and are preferably wound spirally around a winding axis. In some embodiments, the electrodes and the separator(s) are wound onto a cylindrical or hollow-cylindrical winding core, which sits on a winding mandrel and remains in the coil after winding.

[0204] The winding sleeve can be formed, for example, by a plastic film or an adhesive tape. It is also possible for the winding sleeve to be formed by one or more separator windings.

[0205] Preferred embodiments of the first and / or second contact metal sheet

[0206] The contact metal sheet(s) are preferably connected by welding to the respective current collectors with which they are in direct contact. Particularly preferably, they are directly connected by welding to the free edge strip of the anode current collector.

[0207] In preferred embodiments, the contact metal sheets are made of the same material as the current collectors to which they are connected by welding.

[0208] In particularly preferred embodiments, the contact metal sheets, in particular in the case of sodium ion-based energy storage elements according to the invention, consist of aluminum or an aluminum alloy.

[0209] The same alloys that were mentioned in connection with current collectors made of an aluminum alloy can be used as aluminum alloy.

[0210] In other preferred embodiments, the contact metal sheets consist, for example, of nickel or copper or titanium or a nickel or copper or titanium alloy or of stainless steel.

[0211] In a further particularly preferred embodiment of the invention, the first contact metal sheet is characterized by at least one of the immediately following features a. to g.: a. The contact metal sheet has a preferably uniform thickness in the range from 50 μm to 600 μm, preferably in the range from 150 μm to 350 μm. b. The contact metal sheet has two opposite flat sides and extends essentially in only one dimension. c. The contact metal sheet is a disk or a preferably rectangular plate. d. The contact metal sheet is dimensioned such that it covers at least 60%, preferably at least 70%, particularly preferably at least 80%, of the side or end face from which the free edge strip of the respective current collector connected to it emerges. e. The contact metal sheet has at least one opening, in particular at least one hole and / or at least one slot. f.The contact metal sheet has at least one bead, which appears as an elongated depression on one flat side of the contact metal sheet and as an elongated elevation on the opposite flat side, wherein the contact metal sheet rests on the free edge strip of the respective current collector with the flat side bearing the elongated elevation. g. The contact metal sheet is welded to the free edge strip of the current collector in the region of the bead, in particular via one or more weld seams and / or weld spots arranged in the bead.

[0212] It is particularly preferred that the immediately above features a., b., and d. are implemented in combination with one another. In a preferred embodiment, features a., b., and d. are implemented in combination with one of features c. or e., or features f. and g. Particularly preferably, all features a. to g. are implemented in combination with one another.

[0213] Covering the front side as extensively as possible is important for the thermal management of the energy storage element according to the invention. The larger the cover, the easier it is to contact the first edge of the current collector over its entire length. Heat generated in the composite body can thus be effectively dissipated via the contact metal sheet.

[0214] It is particularly advantageous if the contact metal sheet is in direct contact with all turns of a coil, including the innermost and outermost turns of the coil. The at least one opening in the contact metal sheet can be useful, for example, to allow the composite body to be impregnated with an electrolyte.

[0215] Electrical connection of the contact metal sheet(s)

[0216] The contact metal sheet is either electrically connected to the housing or connected to a contact pole which is guided through the housing and is electrically insulated from the housing, or the contact metal sheet is a part of the housing, for example the bottom of a cup-shaped housing part or the cover for such a cup-shaped housing part.

[0217] The electrical contact to the housing or the contact terminal can be realized, in particular, by welding or a mechanical connection. If necessary, the electrical connection can also be made via a separate electrical conductor.

[0218] For optimal connection of the contact metal sheet(s) to the current collectors, it may be preferable to subject the sides or end faces to a mechanical pretreatment. For example, the current collector edges emerging from the end faces of an electrode coil can be deformed to create a suitable receptacle for the raised portions of a contact metal sheet with at least one bead, as described above.

[0219] Preferred design of the housing parts

[0220] Regardless of its shape (e.g., prismatic or cylindrical), the housing of an energy storage element according to the invention is preferably a metal housing. It particularly preferably comprises a cup-shaped housing part and a cover.

[0221] In a preferred embodiment of the invention, the energy storage element according to the invention is characterized by at least one of the following features a. and b.: a. The cup-shaped housing part is made of aluminum, an aluminum alloy, nickel, copper, stainless steel, or nickel-plated steel. b. The lid is made of aluminum, an aluminum alloy, nickel, copper, stainless steel, or nickel-plated steel.

[0222] Particularly preferably, the immediately above features a. and b. are implemented in combination.

[0223] In some embodiments, a direct connection of the free edge strip of one of the current collectors to the housing is desirable. For this purpose, the free edge strip of this current collector can be welded, for example, using a laser to the bottom of a cup-shaped housing part. In this case, this bottom serves as a contact plate.

[0224] Conversely, in some embodiments, it may be provided that a contact plate serves as a cover, i.e. as part of the housing.

[0225] Particularly in the case of sodium-ion cells, it can be provided in particularly preferred embodiments that both the cup-shaped housing part and the lid are made of aluminum or an aluminum alloy.

[0226] Suitable aluminum alloys for the cup-shaped housing part include aluminum alloys of type 1235, 1050, 1060, 1070, 3003, 5052, Mg3, Mg212 (3000 series), and GM55. Also suitable are AlSi, AICuTi, AIMgSi, AISiMg, AlSiCu, AICuTiMg, and AIMg. The aluminum content of these alloys is preferably above 99.5%.

[0227] In some embodiments, the bottom of the cup-shaped housing part is welded in, meaning it is manufactured separately and connected to the side wall(s) by welding. In most cases, however, the cup-shaped housing part is manufactured by deep drawing.

[0228] Preferred rated capacity of the energy storage element

[0229] The nominal capacity of a sodium-ion-based energy storage element according to the invention, designed as a cylindrical round cell, is preferably up to 10,000 mAh. With a form factor of 21 x 70, the energy storage element in one embodiment as a sodium-ion cell preferably has a nominal capacity in the range of 1,000 mAh to 5,000 mAh. Insulation of internal conductors

[0230] In particularly preferred embodiments, the energy storage element according to the invention is characterized by the immediately following features a. to g.: a. It comprises a housing which is sealed in an airtight and liquid-tight manner and which has a metallic cup-shaped housing part with a base and a circular opening at the end, as well as a lid with a circular edge which closes the circular opening at the end. b. The composite body is arranged in an axial orientation in the cup-shaped housing part, with the first end face pointing towards the lid and the second end face pointing towards the base, optionally being in direct contact with the base. c. It comprises an annular seal made of an electrically insulating material which encloses the circular edge of the lid and electrically insulates the cup-shaped housing part and the lid from one another. d.The cup-shaped housing part comprises an inner side and an outer side and, in axial sequence, the base, a central section and a closure section, wherein the central section is cylindrical and in the central section the winding jacket of the composite body designed as a winding is in contact with the inside of the cup-shaped housing part, and in the closure section the annular seal is in press contact with the cover and the inside of the cup-shaped housing part. e. The central section and the closure section are separated by an indentation which runs annularly around the outside of the cup-shaped housing part. f. The contact metal sheet is welded to the free edge strip of the current collector emerging from the first terminal end face and is electrically connected to the cover, preferably likewise by welding. g.The energy storage element comprises at least one insulating element made of an electrically insulating material, which protects the contact metal sheet and / or the first longitudinal edge of the current collector emerging from the first terminal end face and / or a separate electrical conductor fixed to the contact metal sheet from direct contact with the inside of the cup-shaped housing part, in particular in the region of the indentation.

[0231] This measure ensures that the risk of a short circuit in the cell's internal contact area is reduced. Axial forces occurring, for example, during height calibration, generally no longer lead to direct contact between oppositely polarized cell components. This is prevented by at least one insulating element.

[0232] In a first preferred development of this preferred embodiment, the energy storage element according to the invention is characterized by at least one of the immediately following features a. to c.: a. The at least one insulating element is or comprises an insulating tape which is applied to the edge which delimits the end face and protects this from direct contact with the inner side. b. The at least one insulating element is or comprises an annular molded part made of plastic with a preferably L-shaped cross-section, which is applied to the edge which delimits the end face and protects this from direct contact with the inner side. c. The insulating tape or the annular molded part made of plastic has a thickness in the range from 10 pm to 200 pm.

[0233] It is preferred that the immediately above features a. and c. as well as b. and c. are implemented in combination.

[0234] The insulating tape can, for example, be a Kapton / polyimide adhesive tape.

[0235] The ring-shaped plastic part, preferably with an L-shaped cross-section, can be manufactured by injection molding, for example, and slid onto the edge to be protected. It can be made of Teflon or polyamide, for example.

[0236] In a second preferred development of this preferred embodiment, the energy storage element according to the invention is characterized by at least one of the immediately following features a. to c.: a. The at least one insulating element is or comprises an annular insulating element made of plastic, which rests against the inside of the cup-shaped housing part in the region of the indentation and protects it from direct contact with the contact metal sheet. b. The annular insulating element is a partial section of the annular seal. c. The annular insulating element made of plastic has a thickness in the range from 20 μm to 400 μm.

[0237] It is preferred that the immediately above features a. and b. are implemented in combination. Features a. to c. are particularly preferred that they are implemented in combination.

[0238] The annular insulating element can also be an injection-molded part, as can the annular seal. The thickness of the insulating element is preferably in the range of 20 μm to 400 μm.

[0239] The annular insulating element can be made of, for example, Teflon, polyamide, polybutylene terephthalate or a perfluoroalkoxy polymer.

[0240] In a third preferred development of this preferred embodiment, the energy storage element according to the invention is characterized by at least one of the immediately following features a. to d.: a. The at least one insulating element is or comprises an annular plastic part which encloses the contact metal sheet and protects it from direct contact with the inside of the cup-shaped housing part in the region of the indentation. b. The annular plastic part is hollow-cylindrical, comprises a casing, and is delimited on each end side by a circumferential edge. c. The annular plastic part is hollow-cylindrical, comprises a casing, and is delimited on each end side by a circumferential edge, one of the edges being designed as an outwardly directed annular collar and sitting on the contact metal sheet. d. The annular plastic part has a thickness in the range from 20 μm to 600 μm.

[0241] It is preferred that the immediately preceding features a. and b., particularly preferably features a. and b. and d., are implemented in combination. Particularly preferably, the immediately preceding features a. and c. and d. are implemented in combination.

[0242] The ring-shaped plastic part can also be an injection-molded part. The thickness of the plastic part is preferably in the range of 20 μm to 600 μm.

[0243] The plastic part can be made of, for example, Teflon, polyamide, polybutylene terephthalate or a perfluoroalkoxy polymer.

[0244] In a fourth preferred development of this preferred embodiment, the energy storage element according to the invention is characterized by at least one of the immediately following features a. to d.: a. The at least one insulating element is or comprises an electrically insulating plastic coating that surrounds an edge of the contact metal sheet and protects it from direct contact with the inside of the cup-shaped housing part, in particular in the region of the indentation. b. The electrically insulating coating is formed by overmolding the edge of the contact metal sheet.

[0245] It is preferred that the immediately above features a. and b. are implemented in combination.

[0246] Basically, any thermoplastic material with electrically insulating properties is suitable for overmolding the edge of the contact metal sheet. Polyamide, for example, is suitable.

[0247] Combinations of the four particularly preferred embodiments described are also according to the invention. The energy storage element is particularly preferably characterized by a combination of two or more of the four immediately following features a. to d.: a. The at least one insulating element comprises an insulating strip or annular molded part made of plastic, which is applied to the edge that delimits the end face and protects this from direct contact with the inside, i.e. an insulating strip or annular molded part according to the first particularly preferred embodiment, and / or b. the at least one insulating element comprises an annular insulating element that rests against the inside of the cup-shaped housing part in the region of the indentation and protects this from direct contact with the contact metal sheet, i.e. an annular insulating element according to the second particularly preferred embodiment, and / or c.the at least one insulating element comprises an annular plastic part which encloses the contact metal sheet and protects it from direct contact with the inside of the cup-shaped housing part in the region of the indentation, i.e. an annular plastic part according to the third particularly preferred embodiment, and / or d. the at least one insulating element is or comprises an electrically insulating plastic coating which encloses an edge of the contact metal sheet and protects it from direct contact with the inside of the cup-shaped housing part, in particular in the region of the indentation, i.e. a plastic coating according to the fourth particularly preferred embodiment.

[0248] It is preferred that the energy storage element according to the invention is characterized by at least one of the following features a. to c.: a. The cup-shaped housing part has an identical maximum outer diameter in the central section and the closure section. b. In the region of the indentation, the outer diameter of the cup-shaped housing part is reduced by 4 to 20 times the wall thickness of the cup-shaped housing part in this region.

[0249] It is preferred that the immediately above features a. and b. are implemented in combination.

[0250] Cell closure by potting compound

[0251] In a particularly preferred embodiment, the energy storage element according to the invention is characterized by the immediately following features a. to g.: a. It comprises an airtight and liquid-tight housing which has a metallic, cup-shaped housing part with a base and an end opening and a cover which closes the end opening. b. The cover comprises a metallic cover plate and a connection pole which is guided through an opening in the cover plate and is electrically insulated from the cover plate, c. The composite body is arranged in the cup-shaped housing part, with one side of the composite body pointing towards the cover and a second side towards the base, optionally being in direct contact with the base. d.The cathode and the anode are designed and / or arranged relative to one another within the composite body in such a way that the free edge strip of the cathode current collector emerges from the side of the composite body and the free edge strip of the anode current collector emerges from one side of the composite body, and e. The contact metal sheet sits directly on the free edge strip of one of the current collectors emerging from one of the sides of the composite body and is connected to it by welding. f. The contact metal sheet is either electrically connected to the connection pole guided through the opening in the cover plate, preferably directly welded to the connection pole, or the connection pole is part of the contact metal sheet. g. The connection pole is electrically insulated from the cover plate by a cured potting compound made of an electrically insulating plastic material.

[0252] A cover of this design ensures that there is essentially no dead volume between the composite body and the metal cover plate. Any space between the contact metal sheet, the terminal, and the cover plate can be filled with the potting compound. A cover with these features can be built very compactly.

[0253] Furthermore, an energy storage element with the immediately above features a. to g. has the advantage that it is possible to electrically contact both the anode and the cathode via the cover. In a preferred development of this embodiment, the energy storage element according to the invention is characterized by the immediately following feature a.: a. The edge strip of the cathode current collector or the anode current collector that is not in direct contact with the contact metal sheet is electrically connected to the housing base, preferably welded directly to the housing base.

[0254] In many cases, it is preferred in this embodiment for the cup-shaped housing part to be positively polarized and the connection pole to be a negative connection pole. In these cases, the energy storage element according to the invention is characterized by the immediately following feature a., optionally in combination with at least one further of the immediately following features b. and c.: a. The cup-shaped housing part is electrically connected to the cathode. b. The cup-shaped housing part is made of aluminum or an aluminum alloy. c. The cover plate is made of aluminum or an aluminum alloy.

[0255] Particularly preferably, the immediately above features a. to c. are implemented in combination.

[0256] In this embodiment, the housing of the energy storage element consists essentially of aluminum or an aluminum alloy. This offers several advantages. The formation of localized elements when the exterior of the cell comes into contact with moisture is eliminated. The housing itself can essentially serve as the positive terminal on all sides. However, it is particularly preferred that the cell be contacted exclusively via the cover, where the negative terminal is also located. For this purpose, a current conductor can be welded directly to the cover plate or, alternatively, fixed to the separate terminal, for example, by welding.

[0257] In further cases, it may be preferred for the cup-shaped housing part to be negatively polarized and for the connection pole to be a positive connection pole. In these cases, the energy storage element according to the invention is characterized by the immediately following feature a., optionally in combination with at least one further of the immediately following features b. and c.: a. The cup-shaped housing part is electrically connected to the anode. b. The cup-shaped housing part is made of aluminum or an aluminum alloy. c. The cover plate is made of aluminum or an aluminum alloy.

[0258] Particularly preferably, the immediately above features a. to c. are implemented in combination.

[0259] In preferred embodiments, the energy storage element according to the invention is characterized by at least one of the immediately following features a. and b.: a. Between the cover plate and the contact metal sheet there is an annular gap filled with the potting compound. b. The annular gap is radially delimited to the outside by an O-ring-shaped insulating disc made of an electrically insulating plastic material.

[0260] In further particularly preferred embodiments, the energy storage element according to the invention is characterized by at least one of the following features a. to c.: a. The contact metal sheet is made of aluminum or an aluminum alloy. b. The connection pole is made of aluminum or an aluminum alloy. c. The contact metal sheet, the connection pole, and the cathode current collector are made of the same material.

[0261] In embodiments where the terminal pole is part of the contact metal sheet, the contact metal sheet serves simultaneously as a conductor for the current from the anode or cathode current collector and as a pole. Accordingly, no separate electrical conductor is required, as is known from the prior art and is typically arranged between a cover or cover assembly and a contact plate, as described in WO 2017 / 215900 A1.

[0262] In this embodiment, the contact metal sheet preferably comprises a flat region that sits directly on the free edge strip of one of the current collectors emerging from one of the sides of the composite body and is connected to it by welding, and a projection pointing away from this side. The projection serves as the connection pole and is preferably guided through the opening in the cover plate.

[0263] The contact metal sheet is preferably characterized by at least one of the following features a. and b.: a. The projection of the metal part pointing away from the first terminal end face is cup-shaped. b. The contact metal sheet, including the projection, is formed in one piece.

[0264] It is preferred that the immediately above features a. and b. are implemented in combination.

[0265] The contact metal sheet with the cup-shaped projection can be manufactured, for example, in a deep-drawing process; in this case, it is preferably formed in one piece. However, it can also be manufactured, for example, from a metal workpiece through a forming or machining process or by means of 3D printing.

[0266] In a particularly preferred embodiment of the invention, the energy storage element according to the invention is characterized by the following features a. and b.: a. the housing base of the cup-shaped housing part has a primary protection against internal overpressure in the form of an opening closed by a metallic membrane. b. the housing base of the cup-shaped housing part has a secondary protection against internal overpressure in the form of at least one groove on its inside or outside.

[0267] The primary safety device's function is to ensure controlled pressure equalization when an excessive pressure exceeding a defined threshold occurs. In this case, the pressure bursts or ruptures the diaphragm, allowing gas built up inside the housing to escape through the opening in the housing base.

[0268] The secondary fuse is intended for cases where pressure equalization via the primary fuse does not occur quickly enough. In this case, the excess pressure can cause the housing base to rupture along the groove, which represents nothing more than a weakening of the housing base structure, creating an outlet opening with a comparatively large cross-section through which gases formed inside the housing can escape.

[0269] Such safety solutions are already known. By appropriately designing the groove and membrane, the pressure at which the safety devices are triggered can be precisely adjusted.

[0270] Since the aforementioned safety features are integrated into the housing base rather than the lid, as is the case with many conventional cells, it's possible to construct the lid extremely compactly. Pre-assembly of the lid is also not necessary; the lid can be manufactured during the housing assembly process.

[0271] In particularly preferred embodiments, the energy storage element according to the invention is characterized by at least one of the immediately following features a. to e.: a. The cover plate is welded into the terminal opening of the cup-shaped housing part. b. The contact metal sheet is connected to the contact metal sheet of the anode current collector or the free edge strip of the cathode current collector by welding. c. The free edge strip not in direct contact with the contact metal sheet sits directly on the housing base. d. The free edge strip not in direct contact with the contact metal sheet is connected to the housing base by welding. e. The at least one groove is located on the inside of the housing base.

[0272] Preferably, the immediately preceding features a. to d. are implemented in combination, particularly preferably the immediately preceding features a. to e.

[0273] In another particularly preferred embodiment of the invention, the energy storage element according to the invention is characterized by the following feature a.: a. The metallic membrane is fixed by welding to the bottom of the cup-shaped housing part. The bottom of the cup-shaped housing part can have a shallow recess into which the membrane is inserted, so that it does not add bulk. It is preferably connected to the bottom via a circular weld seam that runs around the opening in the bottom.

[0274] The thickness of the membrane can be adjusted to the pressure at which the fuse should trigger.

[0275] In preferred embodiments, the energy storage element according to the invention is characterized by at least one of the immediately following features a. to g.: a. The housing base has at least one bead which appears on its outer side as an elongated depression and on its inner side as an elongated elevation, wherein the edge strip of the cathode current collector or the anode current collector which is not in direct contact with the contact metal sheet sits on the inner side. b. The edge strip of the cathode current collector or the anode current collector which is not in direct contact with the contact metal sheet is electrically connected to the housing base, preferably welded directly to the housing base. c. The housing base is welded in the region of the bead to the free edge strip of the anode current collector or the free edge strip of the cathode current collector. d. The opening is positioned in the center of the housing base. e.The at least one bead comprises a plurality of linear beads, in particular three beads, arranged in a star-shaped arrangement around the opening. f. The at least one bead comprises a plurality of linear subsections arranged in a star-shaped arrangement around the opening. g. The at least one bead comprises a subsection extending around the opening, which connects the star-shaped linear subsections to one another.

[0276] Preferably, the immediately preceding features a. and b., c. and d., as well as c. and e. and f. are implemented in combination. Particularly preferably, the immediately preceding features a. to g. are implemented in combination. As a result of the welding in the region of the bead, one or more weld seams are preferably present therein. The star-shaped beads and the star-shaped linear sections of the groove preferably each enclose an angle of 120°.

[0277] In some embodiments, it has proven advantageous to pretreat the free edge strip of the current collector, which rests on the inside of the housing base, to improve contact between the housing base and the current collector. In particular, at least one recess can be crimped into the edge, corresponding to the at least one bead.

[0278] The edge of the current collector may also have undergone directional deformation through pretreatment. For example, it may be bent in a defined direction.

[0279] Battery according to the invention

[0280] Energy storage elements of the type according to the invention, particularly those based on sodium ion technology, not only offer high power densities, they are also capable of rapid charging, perform well at low temperatures, and offer excellent cycle stability. Furthermore, sodium, for example, is available in virtually unlimited quantities.

[0281] For all these reasons, energy storage elements according to the invention, in particular those based on sodium ion technology, are eminently suitable for use in starter batteries, which can serve as a replacement for lead-acid batteries, for example in motor vehicles.

[0282] The invention described herein accordingly encompasses any battery having two or more energy storage elements according to the invention connected in series and / or parallel to one another, in particular those based on sodium ion technology.

[0283] Particularly preferably, the battery according to the invention comprises a plurality of energy storage elements according to the invention, which are interconnected in such a way that the battery delivers a voltage of 12 volts or 24 volts. Typically, an energy storage element according to the invention based on sodium ion technology delivers a nominal voltage in the range from 1.5 volts to 4.8 volts, preferably from 2.4 volts to 4 volts. Accordingly, a battery according to the invention with a nominal voltage of 12 V preferably comprises 3 to 5 energy storage elements according to the invention connected in series.

[0284] 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.

[0285] Brief description of the drawings

[0286] The drawings show schematically

[0287] Fig. 1 shows a first embodiment of an energy storage element of the sodium ion type according to the invention (cross-sectional view),

[0288] Fig. 2 shows a second embodiment of an energy storage element of the sodium ion type according to the invention,

[0289] Fig. 3 shows a third embodiment of an energy storage element of the sodium ion type according to the invention (cross-sectional view),

[0290] Fig. 4 shows several embodiments of a contact metal sheet suitable for contacting the first longitudinal edge of the current collector emerging from the first terminal end face of an energy storage element of the sodium-ion type according to the invention (perspective view),

[0291] Fig. 5 shows a composite body which is a component of an energy storage element of the sodium ion type according to the invention, as well as its components (top view and perspective view),

[0292] Fig. 6 shows further embodiments of the contact metal sheet suitable for contacting the first longitudinal edge of the current collector emerging from the first terminal end face of an energy storage element of the sodium-ion type according to the invention (perspective view), Fig. 7 shows representations of an embodiment of an energy storage element according to the invention from the outside and in a longitudinal section,

[0293] Fig. 8 Detailed representations of the upper and lower end region of an embodiment of an energy storage element according to the invention in a longitudinal section,

[0294] Fig. 9A,B show detailed views of a connection pole for a preferred embodiment of an energy storage element according to the invention in a view obliquely from above and in a sectional view,

[0295] Fig. 10A,B show detailed views of an insulating disk for a preferred embodiment of an energy storage element according to the invention according to one of Figures 7 to 9 in a view obliquely from above and in a sectional view,

[0296] Fig. 11A,B show detailed views of a contact metal sheet for the preferred embodiment of an energy storage element according to the invention shown in Fig. 7 in a view obliquely from above and in a sectional view obliquely from below,

[0297] Fig. 12 Detailed view of the housing base of a preferred embodiment of an energy storage element according to the invention according to Fig. 7,

[0298] Fig. 13A-C representations of the various components of a preferred embodiment of an energy storage element according to the invention according to Fig. 7 in exploded views,

[0299] Fig. 14A,B show detailed views of the upper end region of a preferred embodiment of an energy storage element according to the invention to illustrate a possible method for producing the energy storage element,

[0300] Fig. 15 Representation of a preferred embodiment of an energy storage element according to the invention obliquely from above onto the housing base to illustrate a method for producing the energy storage element,

[0301] Fig. 16A,B Alternative embodiment of a contact metal sheet with a connecting pole attached thereto and its installation in a preferred embodiment of an energy storage element according to the invention in sectional views, and

[0302] Fig. 17 Example of a cover assembly which can be installed, for example, as a cover in an energy storage element according to the invention as shown in Fig. 1 or Fig. 2 or Fig. 3.

[0303] Detailed description of the implementation examples

[0304] Fig. 1 shows an energy storage element 100 according to the invention with a housing sealed in a ventilated and liquid-tight manner, comprising a metallic, cup-shaped housing part 101 with a circular opening at its end and a cover 102 with a circular edge 102a that closes the circular opening. The energy storage element further comprises an annular seal 103 made of an electrically insulating material, which surrounds the circular edge 102a of the cover 102 and electrically insulates the cup-shaped housing part 101 and the cover 102 from each other.

[0305] The cover is shown only in the form of a disc. However, multi-part cover assemblies are often used, for example, the one shown in Fig. 17.

[0306] The cup-shaped housing part 101 comprises, in axial sequence, a base 101a, a central section 101b, and a closure section 101c, wherein the central section 101b is cylindrical and, in the central section 101b, the winding jacket 104c of the composite body 104 formed as a winding is in contact with the inner side 101d of the cup-shaped housing part 101, and in the closure section 101c, the annular seal 103 is in press contact with the cover 102 and the inner side of the cup-shaped housing part 101. The central section 101b and the closure section 101c are separated by an indentation 111 which runs annularly around the outer side 101e of the cup-shaped housing part 101.

[0307] The composite body 104 in the form of a cylindrical coil with the anode / separator / cathode sequence is not shown in detail here. Only the longitudinal edge 106a of the anode current collector 106, which emerges from the end face 104a of the composite body 104, and the longitudinal edge 109a of the cathode current collector 109, which emerges from the end face 104b of the composite body 104, can be seen. The longitudinal edge 109a is welded directly to the housing base 101a, preferably over its entire length. The longitudinal edge 106a is welded directly to the contact metal sheet 112, preferably over its entire length. The contact metal sheet 112 is in turn connected to the cover 102 via the electrical conductor 133.

[0308] The energy storage element 100 preferably has a height in the range of 60 mm to 100 mm, and its diameter is preferably in the range of 20 mm to 50 mm. The cup-shaped housing part 101 typically has a wall thickness in the range of 0.1 mm to 0.3 mm in the central section 101b.

[0309] The energy storage element comprises an electrically insulating plastic coating 180 as an insulating element, which surrounds the edge of the contact metal sheet 112 and protects it from direct contact with the inner side 101d of the cup-shaped housing part 101, particularly in the region of the indentation 111. The electrically insulating coating 180 is formed by overmolding the edge of the contact metal sheet 112. Furthermore, the energy storage element 100 comprises an annular plastic part 170 as an insulating element, which surrounds the separate electrical conductor 133 fixed to the contact metal sheet and protects it from direct contact with the inner side 101d of the cup-shaped housing part 101 in the region of the indentation 111.

[0310] As a result, the energy storage element 100 is excellently protected against short circuits even in the event of deformation of the housing as a result of an external mechanical force.

[0311] Fig. 2 shows an energy storage element 100 according to the invention with a housing sealed in a ventilated and liquid-tight manner, comprising a metallic, cup-shaped housing part 101 with a circular opening at its end and a cover 102 with a circular edge 102a that closes the circular opening. The energy storage element further comprises an annular seal 103 made of an electrically insulating material, which surrounds the circular edge 102a of the cover 102 and electrically insulates the cup-shaped housing part 101 and the cover 102 from each other.

[0312] The cover is shown only in the form of a disc. However, multi-part cover assemblies are often used, for example, the one shown in Fig. 17.

[0313] The cup-shaped housing part 101 comprises, in axial sequence, a base 101a, a central section 101b and a closure section 101c, wherein the central section 101b is cylindrical and in the central section 101b the winding jacket 104c of the composite body 104 designed as a winding is in contact with the inner side 101d of the cup-shaped housing part 101 (Attention: Solely for reasons of clarity, the composite body 104 is shown spaced apart from the inner side 101d, but in fact it presses against it, as is shown, for example, in Fig. 1), and in the closure section 101c the annular seal 103 is in press contact with the cover 102 and the inner side of the cup-shaped housing part 101.The central section 101 b and the closure section 101 c are separated by an indentation 111 which runs annularly around the outer side 101 e of the cup-shaped housing part 101.

[0314] The composite body 104 in the form of a cylindrical coil with the anode / separator / cathode sequence is not shown in detail here. Only the longitudinal edge 106a of the anode current collector 106, which emerges from the end face 104a of the composite body 104, and the longitudinal edge 109a of the cathode current collector 109, which emerges from the end face 104b of the composite body 104, can be seen. The longitudinal edge 109a is welded directly to the housing base 101a, preferably over its entire length. The longitudinal edge 106a is welded directly to the contact metal sheet 112, preferably over its entire length. The contact metal sheet 112 is in turn connected to the cover 102 via the electrical conductor 133.

[0315] The energy storage element 100 preferably has a height in the range of 60 mm to 100 mm, and its diameter is preferably in the range of 20 mm to 50 mm. The cup-shaped housing part 101 typically has a wall thickness in the range of 0.1 mm to 0.3 mm in the central section 101b.

[0316] The energy storage element comprises, as an insulating element, an annular molded part made of plastic 150 with an L-shaped cross-section, which is applied to the edge that delimits the end face 104a and protects it from direct contact with the inner side 101d of the cup-shaped housing part 101. Furthermore, the energy storage element comprises an annular insulating element 160 made of plastic, which rests against the inner side 101d of the cup-shaped housing part 101 in the region of the indentation 111 and protects it from direct contact with the electrical conductor 133. This can also be a partial section of the annular seal 103, which can be sufficiently high to also cover the indentation 111 from the inside.

[0317] As a result, the energy storage element 100 is excellently protected against short circuits even in the event of deformation of the housing as a result of an external mechanical force.

[0318] Instead of the annular plastic molded part 150 with an L-shaped cross-section, the edge that defines the end face 104a can also be covered with an insulating tape, for example, a Kapton tape 150. Ideally, this can be applied to the edge during the formation of the winding and just as effectively protects the edge from direct contact with the inner side 101d.

[0319] Fig. 3 shows an energy storage element 100 according to the invention with a housing sealed in a ventilated and liquid-tight manner, comprising a metallic, cup-shaped housing part 101 with a circular opening at its end and a cover 102 with a circular edge 102a that closes the circular opening. The energy storage element further comprises an annular seal 103 made of an electrically insulating material, which surrounds the circular edge 102a of the cover 102 and electrically insulates the cup-shaped housing part 101 and the cover 102 from each other.

[0320] The cover is shown only in the form of a disc. However, multi-part cover assemblies are often used, for example, the one shown in Fig. 17.

[0321] The cup-shaped housing part 101 comprises, in axial sequence, a base 101a, a central section 101b, and a closure section 101c, wherein the central section 101b is cylindrical and, in the central section 101b, the winding jacket 104c of the composite body 104 formed as a winding is in contact with the inner side 101d of the cup-shaped housing part 101, and, in the closure section 101c, the annular seal 103 is in press contact with the cover 102 and the inner side of the cup-shaped housing part 101. The central section 101b and the closure section 101c are separated by an indentation 111 which runs annularly around the outer side 101e of the cup-shaped housing part 101.

[0322] The composite body 104 in the form of a cylindrical coil with the anode / separator / cathode sequence is not shown in detail here. Only the longitudinal edge 106a of the anode current collector 106, which emerges from the end face 104a of the composite body 104, and the longitudinal edge 109a of the cathode current collector 109, which emerges from the end face 104b of the composite body 104, can be seen. The longitudinal edge 109a is welded directly to the contact metal sheet 134, preferably over its entire length. The contact metal sheet 134 is in turn connected to the base 101a by welding. The longitudinal edge 106a is welded directly to the contact metal sheet 112, preferably over its entire length. The contact metal sheet 112 is in turn connected to the cover 102 via the electrical conductor 133. The energy storage element 100 preferably has a height in the range of 60 mm to 100 mm, and its diameter is preferably in the range of 20 mm to 50 mm.The cup-shaped housing part 101 typically has a wall thickness in the range of 0.1 mm to 0.3 mm in the central section 101 b.

[0323] The energy storage element comprises an insulating element, an annular plastic part 170, which laterally encloses the electrical conductor 133 and protects it from direct contact with the inner side 101d of the cup-shaped housing part 101 in the region of the indentation 111. The annular plastic part 170 is hollow-cylindrical and comprises a casing 171 perpendicular to the contact metal sheet 112. One of its edges is designed as an outwardly directed annular collar 171 and sits on the contact metal sheet 112.

[0324] As a result, the energy storage element 100 is excellently protected against short circuits even in the event of deformation of the housing as a result of an external mechanical force.

[0325] Fig. 4 shows several embodiments of a contact metal sheet 112 which is suitable for contacting the first longitudinal edge 106a of the current collector 106 emerging from the first terminal end face 104a of an energy storage element 100 according to the invention.

[0326] Embodiment A shows a circular and essentially flat metal disc with a circumferential edge 102a as the contact metal sheet 112. This is characterized by a central hole 142 and three offset beads 141. Such a component can be used in the energy storage elements according to Figures 1 to 3 for electrically contacting the edge 106a of the anode current collector 106. However, it is also suitable for use as the contact metal sheet 134 in the energy storage element according to Figure 3. When using such a metal disc for contacting the longitudinal edge 106a, the separate conductor 133 shown in Figures 1 to 3 is generally required to bridge the distance to the contact metal sheet 102.

[0327] Embodiment B is different. Here, the contact metal sheet 112 comprises a first section 112a, which can sit flat on the first longitudinal edge of the current collector emerging from the first terminal end face 104a and which then extends parallel to the end face 104a. In addition, however, it additionally comprises a second section 112b, which adjoins the first section 112a at an angle and via which the first section 112a is electrically connected to the cover 102. When using such a contact metal sheet, no separate conductor 133 is required. The contact metal sheet 112 is further characterized by a hole 142 and two beads 141. The contact metal sheet is preferably welded to the longitudinal edge of the respective current collector in these beads.

[0328] Embodiments C and D differ from embodiment B in that section 112a comprises three and four strips, respectively, extending in different directions. Each of the strips has a bead 141. In addition, the sheet metal parts each have two holes 142.

[0329] The structure of the composite body 104 is illustrated in Fig. 5. The composite body 104 comprises the strip-shaped anode 105 with the strip-shaped anode current collector 106, which has a first longitudinal edge 106a and a second longitudinal edge parallel thereto. The anode current collector 106 is an aluminum foil. This comprises a strip-shaped main region loaded with a layer of negative electrode material 107, as well as a free edge strip 106b that extends along its first longitudinal edge 106a and is not loaded with the electrode material 107. Furthermore, the composite body 104 comprises the strip-shaped cathode 108 with the strip-shaped cathode current collector 109, which has a first longitudinal edge 109a and a second longitudinal edge parallel thereto. The cathode current collector 109 is also an aluminum foil.It comprises a band-shaped main region loaded with a layer of positive electrode material 110, as well as a free edge strip 109b extending along its first longitudinal edge 109a and not loaded with the electrode material 110. Both electrodes are shown individually in the unwound state.

[0330] The anode 105 and the cathode 108 are arranged offset from one another within the composite body 104, so that the first longitudinal edge 106a of the anode current collector 106 extends from the first terminal end face 104a, and the first longitudinal edge 109a of the cathode current collector 109 extends from the second terminal end face 104b of the composite body 104. The offset arrangement is evident from the illustration at the bottom left. Also shown there are the two band-shaped separators 116 and 117, which separate the electrodes 105 and 108 from one another in the winding.

[0331] The illustration at the bottom right shows the composite body 104 in wound form, as it can be used in an energy storage element according to one of Figures 1 to 4. The electrode edges 106a and 109a protruding from the end faces 104a and 104b are clearly visible. The wound sheath 104c is formed by a plastic film.

[0332] Fig. 6 shows further embodiments of the contact metal sheet 112, which is suitable for contacting the first longitudinal edge 106a of the current collector 106 of an energy storage element 100 according to the invention, emerging from the first terminal end face 104a.

[0333] The embodiments BD shown here differ from the contact metal sheets shown in the embodiments BD of Fig. 4 essentially only in that section 112b is not folded in a Z shape, but rather bent into a U shape. Such contact metal sheets can replace the contact metal sheet 112 and the electrical conductor 133 in the energy storage elements according to Figs. 1 to 3.

[0334] Fig. 7A-C shows a preferred embodiment of an energy storage cell according to the invention in a view obliquely from above (Fig. 7A), in a longitudinal section (Fig. 7B), and in a view obliquely from below (Fig. 7C). The energy storage cell 100 has the shape of a cylindrical round cell. The housing of the energy storage cell 100 is formed by a cup-shaped housing part 101 and a cover. The cover comprises a cover plate 102a, which has the shape of a perforated plate, and a connection terminal 102b in the center of the cover component.

[0335] As can be seen in the sectional view in Fig. 2B, the winding-shaped composite body 104 is located inside the energy storage cell 100, which is formed from the wound electrode strips with separator strips in between.

[0336] Fig. 2C shows the underside of the energy storage cell 100, which is formed by the housing base 101a. Three star-shaped welded impressions in the form of beads 161 are arranged in the housing base 101a. These beads appear as a depression on the outside and as an elongated elevation on the inside. The longitudinal edge of the respective current collector rests on the inside of these beads 161, and in the area of ​​these beads, the current collector is preferably directly welded to the housing base.

[0337] Aluminum is preferably used as the material for the housing base 101a and the entire cup-shaped housing part 101.

[0338] In the present example, two safety functions are integrated into the housing base 101a. First, there is an opening in the center of the housing base 101a, which is sealed with a metallic membrane 114. In the event of excess pressure due to a cell malfunction, this membrane 114 causes pressure equalization by either bursting or detaching the membrane due to the pressure. In this way, any gas that may have formed inside the cell can escape through the opening in the housing base 101a (primary safety).

[0339] Furthermore, a further securing function is provided in the housing base 101a, which is realized by three star-shaped grooves 166. These grooves 166 represent weakenings in the structure of the housing base 101a and thus form predetermined breaking points in the event of excess pressure occurring inside the cell (secondary securing). In this exemplary embodiment, the grooves 166 are located on the inner side of the housing base 101a and are therefore shown as dashed lines in Fig. 7C. The grooves 166 can be realized, for example, as three scoring lines. The star-shaped arrangement of the scoring lines is further developed by a partially circular connection of the scoring lines or the grooves 166.At a correspondingly high overpressure, the housing base 101a tears open along the grooves 166 and the part-circular connection of these grooves, so that an outlet opening with a comparatively large cross-section is created, through which any gas formed in the interior of the housing can quickly escape.

[0340] Fig. 8A,B shows an enlarged view of the end-face areas of the embodiment of the energy storage cell 100 according to Fig. 7. Fig. 8A shows details of the end face with the cover 102. The cover 102 comprises the cover plate 102a with a central opening and the connection pole 102b arranged in the center of the cover plate 102a. In this exemplary embodiment, for example, the connection pole 102b can form the negative pole and the surrounding cover plate 102a can form the positive pole of the energy storage cell 100.

[0341] Below the terminal 102b is the contact metal sheet 112, which rests on the free edge strip 106b of the spirally arranged anode current collector of the negative electrode and is welded thereto. The contact metal sheet 112 is electrically connected, in particular by welding, to the terminal 102b, which is formed from two metallic components. The cover plate 102a is electrically insulated from the contact metal sheet 112 by an O-ring-shaped insulating disc 177. Furthermore, an electrically insulating potting compound 113 is located in a gap between the terminal 102b and the cover plate 102a.

[0342] Fig. 8B shows details of the opposite end face of the energy storage cell 100. The free edge strip 109b of the cathode current collector is directly electrically connected, in particular welded, to the housing base 101a on this end face of the energy storage cell 100. The casing of the cup-shaped housing part 101 provides electrical contact with the metallic cover plate 102a on the opposite end face, so that the positive potential of the cell can also be tapped on the upper end face of the energy storage cell 100.

[0343] The preferred safety functions of the cell against overpressure according to the invention can be seen on the lower end face of the energy storage cell 100 shown in Fig. 8B. The primary safety device is formed by the metallic membrane 114, which closes a central circular opening 155 in the housing base 101a. The secondary safety device is formed by the grooves 166, whereby one of the three star-shaped grooves 166 can be seen in section in this illustration. The grooves 166, which are located on the inside of the housing base 101a, represent a defined weakening structure in the housing base, so that when a relatively high overpressure develops inside the cell, these structures open and gas can escape.

[0344] The preferred design of an energy storage cell 100 according to the invention, illustrated in Figure 8, allows for a reduced number of parts in the upper region of the energy storage cell (Figure 8A), with the negative and positive terminals of the cell being arranged in this upper region. In particular, this design eliminates the need for additional arresters due to the one-piece construction of the terminal pole 102b.

[0345] The direct contacting of the longitudinal edge of one of the electrode strips on the side of the housing base (partial figure 8B) also serves to ensure the particularly compact design of the cell, so that no dead volumes are required for the various functions of the cell.

[0346] Furthermore, the direct contacting of the longitudinal edges of the electrode strips results in improved heat dissipation and a reduction in internal resistance.

[0347] In addition, the design of this cell generally allows for the formation of longer coils and thus a greater energy density of the resulting energy storage cell.

[0348] In this embodiment, the upper end face of the energy storage cell 100 is designed to be as compact as possible. If gases develop inside the cell, leading to a pressure increase, these gases are inevitably directed into the lower region of the cell, where the safety functions for pressure equalization are located. Overall, such a cell therefore exhibits a very high level of safety.

[0349] Fig. 9A,B shows a detailed representation of the connection pole 102b from Figures 7 and 8 in a view obliquely from above (Fig. 9A) and in a sectional view (Fig. 9B). The connection pole 102b can be composed of two metallic components. The upper region (upper pole part) 1020 does not necessarily have to be made of the same metal as the lower region (lower pole part) 1021. The upper region 1020 has a bevelled, circumferential upper edge. As can be seen in the sectional view according to Fig. 4B, the lower region 1021 is provided with an outer circumferential welding shoulder 1021a and a central, downwardly projecting pin 1021b. The pin 1021b expediently engages in a correspondingly provided recess in the center of the contact metal sheet 112 and thus ensures a good fit of the connection pole 102b.

[0350] Fig. 10A,B shows the O-ring-shaped insulating disk 177 in a complete view obliquely from above (Fig. 10A) and in a sectional view (Fig. 10B). The insulating disk 177 serves, on the one hand, to electrically insulate the preferably positively polarized cover plate 102a from the components of the energy storage cell 100 with reversed polarity. Furthermore, the insulating disk 177 also achieves a liquid-tight and airtight closure of the housing.

[0351] In the preferred embodiment of the insulating disk 177 shown here, the insulating disk is made of two different materials. The outer region 177a of the insulating disk 177 is preferably made of a particularly strong plastic material, for example PBT (polybutylene terephthalate). The inner region 177b is preferably made of a somewhat more flexible and, above all, particularly heat-resistant plastic, for example PET (polyethylene terephthalate). The outer region 177a thus ensures particular mechanical stability. The inner region 177b ensures flexibility and is particularly resistant to the potting compound 13, which is applied hot during assembly of the energy storage cell.

[0352] Particularly advantageously, the inner circumference of the O-ring-shaped insulating disc 177 has a circumferential thickening, which further supports the stability of the components in the front area of ​​the mounted energy storage cell.

[0353] During assembly of the energy storage cell, the insertion of the insulating disk 177 in the cover area of ​​the cell initially temporarily seals the cell until the subsequently applied potting compound 113 has hardened to completely seal the cell. Furthermore, the special shape of the insulating disk 177 allows axial support of the coil-shaped composite body 104, for example during testing of the cell. If the cell is laterally deformed, the shape of the insulating disk 177 also provides space for any deformation of the contact metal sheet 112 that may occur. Finally, the shape of the insulating disk 177 makes it possible to reduce the volume of the potting compound 113 and the amount of air bubbles that may be trapped during potting during assembly of the energy storage cell.

[0354] As a possible alternative to such an insulating washer, an insulating sealing bead, comparable to a silicone bead, can be applied. This can also ensure a tight seal. However, the insulating washer 177, particularly in the embodiment illustrated here, offers the various advantages mentioned.

[0355] Fig. 11A,B shows a preferred embodiment of the contact metal sheet 112, which is provided for contacting the free edge of the current collector of the respective electrode in the upper region of the energy storage cell. Fig. 11A shows a plan view of the disc-shaped contact metal sheet 112. Fig. 11B shows a section through the contact metal sheet 112 in a view from below, i.e., of the side of the contact metal sheet facing the composite body 104 inside the energy storage cell.

[0356] Comparable to the beads 161 of the housing base 101a, the contact metal sheet 112 also has three star-shaped beads 112d, which appear as a depression on the outside (Fig. 11 A) and as an elongated elevation on the inside (Fig. 11 B). The beads 112d can, for example, be embossed and have a depth of, for example, 0.25 mm. In the assembled state of the cell, the beads 112d are in contact with the respective longitudinal edge of an electrode strip of the composite body to be contacted via them. The contact metal sheet 112 is preferably welded to the respective longitudinal edge of the electrode strip via the beads 112d.

[0357] A recess 112e is located in the center of the contact metal sheet 112. The recess 112e serves to accommodate the connecting pole 102b, with the central pin 1021b of the connecting pole 102b engaging in the recess 112e. In this way, the connecting pole 102b can be easily positioned and fixed on the contact metal sheet 112, allowing the connecting pole 102b to be welded on without difficulty.

[0358] Furthermore, in the particularly preferred embodiment of the contact metal sheet 112 shown here, further star-shaped narrow depressions 112f are provided, which are located on the inward-facing side of the contact metal sheet 112. In this exemplary embodiment, a total of nine of these depressions 112f are provided as narrow grooves arranged in a star shape. The grooves can, for example, have a depth of 0.1 mm. The depressions 112f serve to improve the distribution of the electrolyte within the cell. Furthermore, the contact metal sheet 112 in this preferred embodiment has an embossed circumferential edge 112g, which is arranged as a predetermined bending point, in particular with the ridge facing downwards. This predetermined bending point facilitates the assembly of the housing of the energy storage cell.

[0359] In preferred embodiments, the contact metal sheet 112 is made of aluminum, for example from an aluminum sheet with a material thickness of 0.3 mm.

[0360] Fig. 12 shows a detailed view of the housing base 101a of the energy storage cell with the star-shaped, inwardly projecting beads 161, which are designed in particular as welded impressions for contacting the coil-shaped composite body. The star-shaped arrangement with three beads 161 is particularly advantageous for cell assembly due to its rotational symmetry.

[0361] The central opening 155 in the housing base 101a is covered by a metallic membrane 114 and serves as primary protection for the cell in the event of excess pressure. In particular, it is intended that the opening 155 is initially used during cell manufacture to fill the cell with electrolyte before the opening 155 is sealed with the metallic membrane 114.

[0362] For a precise fit of the metallic membrane 114 for closing the central opening 155, a circumferential recess 1010b is preferably provided which surrounds the central opening 155.

[0363] Furthermore, this embodiment features three star-shaped weakening structures in the form of inwardly open grooves 166, which are connected to each other by a partially circular connecting line 1010c. These weakening structures 166 and 1010c serve as secondary protection against internal overpressure. As an alternative to applying the weakening structures from the inside to the housing base, such weakening structures, for example, scoring lines, can also be applied from the outside.

[0364] On the outside of the housing base 101a, one or more labeling fields 1010a can also be provided, which can be used for the attachment of various written information.

[0365] Fig. 13A-C show exploded views of the various components of a preferred embodiment of an energy storage cell according to the invention. Fig. 13A shows the components of the housing, including the housing cup 101, the terminal 102b, the O-ring-shaped insulating disk 177, the cover plate 102 with the central recess into which the terminal 102b engages, and the potting compound 113. Below the housing cup 101, the closure for the energy storage cell is shown in the form of the metallic membrane 114. This closure is applied after the assembled cell has been filled with the electrolyte 115, indicated schematically here.

[0366] Fig. 13B shows the coil-shaped electrode-separator composite body 104 and the contact metal sheet 112 to be attached thereto. The composite body 104 can be produced in a conventional manner by winding the electrode strips and the separators, in particular on a winding machine. To complete the winding, the outermost winding turn can preferably be bent inward by, for example, 30° to 45° using a conical pressure piece, so that the winding shape is stabilized. An adhesive tape 118 (Fig. 13C), for example made of polypropylene, is then preferably applied to the outer circumferential surface of the coil. This adhesive tape, in addition to its stabilizing function, may also optionally perform an electrically insulating function in the cell.After stabilizing the wound composite body 104, the disc-shaped contact metal sheet 112, which is made of aluminum, for example, can be loosely placed on the upper end face of the coil and secured with a particularly strong adhesive tape 119 made of, for example, polyimide. For this purpose, a Kapton® tape with a thickness of 50 μm can be used.

[0367] The composite body 104, with the attached contact metal sheet 112, can then be inserted into the cup-shaped housing part 101. After a camera-assisted alignment of the beads in the housing base and in the contact metal sheet, if necessary, the assembly can be pressed together using suitable pressing tools and simultaneously or sequentially laser-welded from above and below to contact the longitudinal edges of the electrode strips with the respective beads. The connecting pole 102b can then be placed and welded onto the contact metal sheet 112.

[0368] Fig. 14A,B shows details of the production of the cell cover assembly. Fig. 14A shows a detailed view of the welding of the connection pole 102b onto the contact metal sheet 112, whereby the laser can act at an angle or vertically, particularly in the area of ​​the circumferential welding shoulder 1021a of the connection pole 102b. Fig. 14B shows how the insulating disk 177 can then be inserted and pressed to the correct height before the cover plate 102a is placed on top and welded at an angle, vertically, or horizontally to the cup-shaped housing part (not shown here). Now, the connection pole 102b can be pressed, if necessary, to the correct height relative to the cell shoulder formed by the upper side of the cover plate 102a. The distance provided for this purpose can be, for example, 1 mm between the upper side of the connection pole 102b and the upper side of the cover plate 102a.The gap between the cover plate 102a and the connection pole 102b is filled with a potting compound 113 in order to seal this part of the energy storage cell in an airtight and liquid-tight manner.

[0369] The energy storage cell can then be transferred to an oven to cure the potting compound 113 and to bake out the residual moisture from the coil-shaped composite body.

[0370] Fig. 15 illustrates the final filling with electrolyte 115, which is introduced from the underside of the energy storage cell 100 (top in this illustration) through the opening 101b in the housing base 101a. Finally, the metallic membrane 114 is applied as a closure to the opening in the housing base 101a or as a closure to the central opening 155. For this purpose, a vertical laser beam can be used, for example.

[0371] Fig. 16 illustrates an alternative way of mounting the cover assembly. Fig. 16A shows the contact metal sheet 112 with the attached terminal 102b in a sectional view obliquely from below. Fig. 16B shows the upper end face of the cell in a longitudinal section.

[0372] In this alternative manufacturing process, the terminal pole 102b is pre-welded to the contact metal sheet 112. Friction welding or friction stir welding can be used for this purpose.

[0373] When designing the contact metal sheet 112 in this embodiment, the star-shaped beads 112d of the contact metal sheet 112 can be shortened if necessary, since they are covered by the connecting pole 102b during the subsequent welding of the electrode-separator composite body. Overall, therefore, somewhat less welding surface is available for contacting the longitudinal edge of the respective electrode strip with the contact metal sheet 112. However, this design can offer advantages for assembly.

[0374] Since the attachment of the connection pole 102b directly on the contact metal sheet 112 outside the housing cup assembly may be easier to carry out, a central recess in the contact metal sheet and a corresponding pin on the connection pole 102b may be omitted.

[0375] The further assembly of the energy storage cell with the connection pole 102b, which is already welded directly onto the contact metal sheet 112, does not differ in principle from the previously described manufacturing process for the energy storage cell 100.

[0376] Fig. 17 shows an example of a cover assembly 202 which can be installed as a cover in an energy storage element according to the invention according to Fig. 1 or Fig. 2 or Fig. 3.

[0377] This comprises the metal disk 213 with the metallic diaphragm 214, which bulges outward or bursts when excess pressure occurs within the housing. The metal disk 213 with the diaphragm 214 is in direct electrical contact with the metallic pole cap 217, which seals off the cover assembly 202 from the outside. It is also in electrical contact with an inner metallic contact disk 215, but exclusively via the metallic diaphragm 214. Otherwise, the metal disk 213 and the contact disk 215 are electrically insulated from one another by the annular insulator 216. If the diaphragm 214 bulges outward as a result of excess pressure, which can act directly on the diaphragm via the opening 215a, the electrical contact between the metal disk 213 and the contact disk 215 breaks. At high pressures, the diaphragm can also burst.The arresters 113 of the cells shown in Figures 1 to 3 can be welded to the contact disk 213.

Claims

Patent claims 1. Secondary energy storage element (100) with the following features: a. It comprises a cathode (108) and an anode (105) as electrodes, which are parts of a composite body (104) in which they are present in the sequence cathode (108) / separator or solid electrolyte layer (116) / anode (105), separated by a separator or solid electrolyte layer (116), b. the cathode (108) comprises a cathode current collector (109) and a positive electrode material (110), c. the anode (105) comprises an anode current collector (106) and a negative electrode material (107), d.the cathode current collector (109) has a main region which is loaded on both sides with a layer of the positive electrode material (110), and a free edge strip (109b) which extends along an edge (109a) of the cathode current collector (109) and which is not loaded with the positive electrode material (110), and / or the anode current collector (106) has a main region which is loaded on both sides with a layer of the negative electrode material (107), and a free edge strip (106b) which extends along an edge (106a) of the anode current collector (106) and which is not loaded with the negative electrode material (107), e.the cathode (108) and the anode (105) are designed and / or arranged relative to one another within the composite body (104) in such a way that the free edge strip (109b) of the cathode current collector (109) emerges from one side (104b) of the composite body (104) and / or the free edge strip (106b) of the anode current collector (106) emerges from another side (104a) of the composite body (104), and f. the energy storage element comprises a first contact metal sheet (112) which is in direct contact with one of the free edge strips (106b) and / or a second contact metal sheet (101a) which is in direct contact with the other of the. free edge strip (109b) is in direct contact, wherein g. the electrodes (105, 108) comprise at least one ion type from the group consisting of sodium ions, potassium ions, calcium ions, magnesium ions and aluminum ions, which are exchanged between the cathode (108) and the anode (105) during charging and discharging of the secondary energy storage element (100).

2. Energy storage element according to claim 1, having the following additional features: a. The electrodes (105, 108) and the current collectors (106, 109) as well as the layers of electrode materials (107, 110) are strip-shaped, b. It comprises at least one strip-shaped separator (116) or at least one strip-shaped solid electrolyte layer, c. the composite body (104) is in the form of a coil in which the electrodes (105, 108) and the at least one separator (116) are wound around a winding axis, wherein the composite body (104) comprises a first and a second terminal end face (104a, 104b) and a winding jacket (104c) and the free edge strip (109b) of the cathode current collector (109) emerges from the first end face (104b) and / or the free edge strip (106b) of the anode current collector (106) emerges from the second end face (104a), d.It comprises a housing, in particular a metal housing, comprising a housing shell or side walls and, on the end faces, a base (101a) and a cover (102), and e. In the housing, the composite body (104) designed as a coil is oriented such that the coil shell (104c) rests against the inner side (101d) of the housing shell or the side walls.

3. Energy storage element according to claim 1, having the following additional features: a. The composite body (104) is in the form of a prismatic stack in which the cathode (108) and the anode (105) are stacked together with further cathodes (108) and anodes (105). b. The electrodes (105, 108) and the current collectors (106, 109), as well as the layers of the electrode materials, are polygonal, in particular rectangular. c. It comprises at least one strip-shaped or polygonal, in particular rectangular, separator (116) or at least one strip-shaped or polygonal, in particular rectangular, solid electrolyte. d. The stack is enclosed by a prismatic housing.

4. Energy storage element according to one of the preceding claims, with at least one of the following additional features: a. The energy storage element (100) is a sodium-ion cell. b. The energy storage element comprises a sodium-ion cell. c. The energy storage element comprises one of the following electrolytes: NaCIO4 dissolved in at least one organic solvent, in particular in PC or in a carbonate mixture from the group comprising EC / DEC / FEC and PC / FEC; NaPF6 and / or NaTFSI dissolved in at least one organic solvent, in particular in PC or in a carbonate mixture from the group consisting of EC / DEC / FEC, EC / PC, EC / DEC, FEC / EMC and PC / FEC or in an ether mixture such as THF / mTHF; NaFSI and / or NaTFSI and / or NaTDI dissolved in at least one organic solvent, in particular in 1,4-dioxane (DX) and / or 1,3-dioxolane (DOL) and / or dimethyl ether (DME); NaFSI and / or NaTFSI and / or NaTDI dissolved in at least one organic solvent, in particular in dimethyl carbonate (DX) and / or tris(2,2,2-trifluoroethyl)phosphate (TFP); NaN(SO2F)2dissolved in at least one organic solvent, in particular in 1,4-dioxane (DX) and / or 1,3-dioxolane (DOL) and / or dimethyl ether (DME); NaBF4 dissolved in at least one organic solvent, in particular in tetraethylene glycol dimethyl ether (TEGDME) and / or in ACN and / or in PC and / or GBL.

5. Energy storage element according to one of the preceding claims with at least one of the following additional features: a. The anode comprises a matrix with depressions and / or pores in which metallic sodium is embedded. b. The matrix adheres to the surface of the anode current collector. c. The matrix comprises carbon particles and a binder. d. The matrix comprises conductive agents and / or fillers. e. The matrix is ​​a roughened surface of the anode current collector.

6. Energy storage element according to one of claims 1 to 4, with the following additional feature: a. The anode comprises a nucleation layer in which metallic sodium is embedded and / or on which metallic sodium is deposited. b. The nucleation layer consists essentially of at least one material from the group consisting of tin, silver, gold, germanium, carbon, platinum, zinc, aluminum, magnesium, and silicon. c. The nucleation layer was deposited on the surface of the anode current collector by means of PVD (physical vapor deposition) or OVD (chemical vapor deposition).

7. Energy storage element according to claim 6 with at least one of the following additional features: a. The negative electrode comprises the layer sequence metallic current collector / matrix or nucleation layer and cover layer. b. The nucleation layer is thus arranged between the cover layer and the current collector. c. The cover layer has a thickness in the range from 300 nm to 30 pm. d. The cover layer is formed from a ceramic material or comprises such a ceramic material. e. The cover layer comprises or is formed from aluminum oxide (Al2O3), aluminum hydroxide or aluminum oxide hydroxide (AlOOH), silicon oxide (SiO x with x in the range >1 and <2), titanium oxide (TiO2), titanium nitride (TiN), titanium aluminum nitride (TiAIN) or titanium carbonitride (TiCN).

8. Energy storage element according to one of claims 2 or 4-7 with at least one of the following additional features: a. It comprises a housing which is sealed in an airtight and liquid-tight manner and which has a metallic, cup-shaped housing part (101) with the base (101a) and a circular opening at the end, as well as a cover (102) with a circular edge (102a) which closes the circular opening at the end. b. The composite body (104) is arranged in an axial alignment in the cup-shaped housing part, with the first end face (104a) pointing towards the cover (102) and the second end face (104b) pointing towards the base (101a), optionally being in direct contact with the base (101a). c.It comprises an annular seal (103) made of an electrically insulating material, which surrounds the circular edge (102a) of the cover (102) and electrically insulates the cup-shaped housing part (101) and the cover (102) from each other. d. The cup-shaped housing part (101) comprises an inner side (101d) and an outer side (101e) and, in axial sequence, the base (101a), a central section (101b) and a closure section (101c), wherein the central section (101b) is cylindrical and, in the central section (101b), the winding jacket (104c) of the composite body (104) designed as a winding is in contact with the inner side (101d) of the cup-shaped housing part (101), and, in the closure section (101c), the annular seal (103) is in press contact with the cover (102) and the inner side of the cup-shaped housing part (101). e.The central section (101b) and the closure section (101c) are separated by an indentation (111) which runs annularly around the outer side (101e) of the cup-shaped housing part (101). f. The contact metal sheet (112) is welded to the free edge strip (106b) of the current collector emerging from the first terminal end face (104a) and is electrically connected, preferably likewise by welding, to the cover (102). g. It comprises at least one insulating element (150; 160; 170; 180) made of an electrically conductive material. trically insulating material which protects the contact metal sheet (112) and / or the free edge strip (106b, 109b) of the current collector (106, 109) emerging from the end face (104a) and / or a separate electrical conductor (133) fixed to the contact metal sheet (112) from direct contact with the inside (101d) of the cup-shaped housing part (101), in particular in the region of the indentation (111).

9. Energy storage element according to one of claims 1 to 7 with at least one of the following additional features: a. It comprises a housing which is sealed in an airtight and liquid-tight manner and which has a metallic, cup-shaped housing part (101) with a base (101a) and an end opening, as well as a cover (102) which closes the end opening. b. The cover (102) comprises a metallic cover plate (102a) and a connection pole (102b) which is guided through an opening in the cover plate (102) and is electrically insulated from the cover plate (102). c. The composite body (104) is arranged in the cup-shaped housing part, with one side (104a) of the composite body pointing towards the cover (102) and a second side (104b) towards the base (101a), optionally being in direct contact with the base (101a). d.The cathode (108) and the anode (105) are designed and / or arranged relative to one another within the composite body (104) in such a way that the free edge strip (109b) of the cathode current collector (109) emerges from the side (104b) of the composite body (104) and the free edge strip (106b) of the anode current collector (106) emerges from one side (104a) of the composite body (104), and e. The contact metal sheet (112) sits directly on the free edge strip of one of the current collectors emerging from one of the sides of the composite body and is connected to it by welding. f. The contact metal sheet (112) is either electrically connected to the connecting pole (102b) passing through the opening in the cover plate (102a), preferably directly welded to the connecting pole (102b), or the connecting pole (102b) is part of the contact metal sheet (112). g. The connecting pole (102b) is covered by a hardened potting compound (113). an electrically insulating plastic material from the cover plate (102).

10. Energy storage element according to claim 9 with the following additional feature: a. The edge strip of the cathode current collector (109) or the anode current collector (106) which is not in direct contact with the contact metal sheet (112) is electrically connected to the housing base (101a), preferably welded directly to the housing base (101a).

11. Energy storage element according to one of claims 9 or 10, with at least one of the following additional features: a. Between the cover plate (102) and the contact metal sheet (112) there is an annular gap filled with the potting compound (113). b. The annular gap is radially delimited outwardly by an O-ring-shaped insulating disc (177) made of an electrically insulating plastic material.

12. Energy storage element according to one of claims 9 to 11 with the following additional features: a. The housing base (101a) of the cup-shaped housing part (101) has a primary protection against internal overpressure in the form of an opening (155) which is closed by a metallic membrane (114), b. The housing base (101a) of the cup-shaped housing part (101) has a secondary protection against internal overpressure in the form of at least one groove (166) on its inside or outside.

13. A battery comprising at least two energy storage elements according to one of the preceding claims, which are connected in parallel and / or in series.

14. Battery according to claim 13, characterized in that it has a nominal voltage of 12V or 24V.

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