High-temperature accumulator with at least one planar cell

Abstract

High-temperature accumulator with at least one planar cell (1) having an anode-side electrode (2), a separator (4), and a cathode-side electrode (6) arranged one behind the other along a central axis (1.1), wherein an anode compartment (3) is formed between the anode-side electrode (2) and the separator (4), and a cathode compartment (5) is formed between the separator (4) and the cathode-side electrode (6), and an insulator unit (7) is provided which mechanically connects the anode-side electrode (2) and the cathode-side electrode (6) and which is indirectly connected to the separator (4) in a joining zone (B) via a solder or intermediate layers, wherein the anode-side electrode (2) has a disc-shaped form rotationally symmetrical to the central axis (1.1), with an electrode base (2.1) and an electrode wall (2.2) which is formed in a (2.1) parallel electrode edge (2.3) passes over, with the electrode wall (2.2) encloses an electrode wall angle (α2) with the electrode base (2.1), and the separator (4) has a shape rotationally symmetrical to the central axis (1.1), with a separator base (4.1) and a separator wall (4.2) which transitions into a separator rim (4.3) parallel to the separator base (4.1), wherein the separator wall (4.2) encloses a separator wall angle (α4) with the separator base (4.1), wherein the electrode rim (2.3) and the separator rim (4.3) are in contact with each other indirectly via the insulator unit (7), characterized in that the separator wall (4.2) and the electrode wall (2.2) are electrically insulated from each other and sealed by at least one barrier seal, whereby the anode space (3) is limited by the anode-side electrode (2), the separator (4) and the seal, so that the joining zone (B) lies outside the anode space (3) and cannot come into contact with liquid or solid chemical substances located in the anode space (3).

Description

[0001] A cell of a rechargeable battery (e.g. Na / NiCl2) basically consists of the following cell components, which are considered in the charged state: • Cathode-side electrode:

[0002] Suitable materials for the cathode-side electrode include metals or metal alloys that are chemically stable with respect to the liquid secondary electrolyte NaAlCl4, do not participate in the chemical reactions within the cell (cell chemistry), and are therefore not subject to corrosion. They must possess good electrical conductivity. The required corrosion resistance depends, among other things, on the operating temperature of the battery (up to 350°C) and the surrounding media. Consequently, the corrosion resistance requirements for a cell are comparatively lower when it is surrounded by a vacuum instead of oxygen-enriched ambient air. Therefore, depending on the operating conditions, steels, steels with various alloying elements, and metallic coatings such as nickel can be used. • Cathode space:

[0003] The size of the cathode compartment limits the electrical storage capacity of the battery, as this compartment contains the cathode material involved in the chemical reaction. While a larger cathode compartment increases the electrical storage capacity, it leads to reduced charging / discharging currents due to the increased resistance in the cathode material. This resistance depends on the electrical conductivity of the cathode material itself and the distances between the conductor (cathode-side electrode) and the separator, as well as the contact resistances. The cathode compartment must be hermetically sealed to prevent oxygen or other elements that could influence the reaction from entering the cell. • Cathode material:

[0004] Cathode material refers to all materials that are located in the cathode space when the cell is charged, especially chemical substances.

[0005] The chemical substances in high-temperature accumulators include, for example, alkali metals, especially sodium, and metal halides.

[0006] In the charged state, the cathode compartment of a sodium / nickel chloride cell contains nickel and metal chloride as the active medium, optionally unreacted NaCl, and the sodium ion-conducting liquid secondary electrolyte NaAlCl4. According to the prior art, additives such as nal, NaBr, NaF, and sulfur are added to ensure stable cell operation for more than 2000 cycles. Aluminum is added to produce excess sodium. Nickel is preferably used for high-temperature batteries as an electrically conductive network and for the formation of NiCl2 (Na / NiCl2) due to its high electrochemical potential, its chemical resistance to NaAlCl4, its availability, and also its cost. Iron- or zinc-based systems have not yet become established. The cathode material, considered in the charged state, contains no undissolved sodium chloride when fully charged. • Separator:

[0007] The solid electrolyte (separator) of a high-temperature battery consists of a sodium-ion-conducting ceramic, in particular sodium beta-aluminate. The separator electrically and spatially separates the cathode compartment from the anode compartment. In a temperature range between 250 and 350°C, it exhibits high sodium ion conductivity (values ​​of ≥ 0.2 S / cm can be achieved at 300°C). At temperatures above 350°C, only slight increases in conductivity are observed, while the demands on the sealing system increase. If the operating temperature is reduced below 250°C, the ionic conductivity decreases rapidly, and the wetting of the ceramic deteriorates; consequently, the interfacial resistances also increase. • Anode compartment:

[0008] The metallic sodium formed during the charging process is deposited in the anode compartment. For improved contact and thus reduced ohmic resistance, an open-pored, electrically conductive filler, such as metal wool, can be inserted between the separator and the anode-side electrode. This ensures good electrical contact between the anode-side electrode and the separator, while allowing sodium to infiltrate the free spaces; alternatively, metal sheets can be used. The free volume in the anode compartment and the corresponding amount of sodium deposited, together with the internal pressure prevailing in the anode compartment before charging, determine, among other things, the actual operating pressure in the anode compartment according to the charging / discharging states. • Anode-side electrode:

[0009] The anode-side electrode is electrically conductive. The material used, like that of the cathode-side electrode, must be resistant to the surrounding atmosphere. Furthermore, chemical resistance to liquid sodium is required. • Insulator:

[0010] The insulator or insulator unit is typically made of corundum (Al₂O₃) and therefore has a higher strength than a separator made of sodium beta-aluminate, as the latter should be designed to be as thin as possible to minimize the overall resistance of the cell. Consequently, if the separator is used as an electrically insulating connection between the two electrodes, it might not withstand the thermomechanical forces acting in the respective joining zones. Furthermore, direct or indirect contact of the separator in the anode compartment with an electrically conductive material, such as the electrodes, would lead to the deposition of liquid sodium, which would negatively affect the tightness of the joining zone.Therefore, it is necessary to use an insulator, which, preferably for cost reasons and due to a suitable coefficient of thermal expansion, can be made of a ceramic, preferably corundum, that electrically separates the anode-side and cathode-side electrodes from each other and is chemically resistant to the cathode material or sodium. Together with the shape of the anode-side and cathode-side electrodes, the insulator also determines the distance between the electrodes and the separator. • Spacers in accumulators, formed from several planar cells:

[0011] The individual cells of a high-temperature accumulator are electrically connected to each other and arranged so that they can be installed in a housing with the densest possible packing. Planar cells are typically stacked, with or without space between them. To stack them with a gap between them, spacers, preferably made of sheet metal components, can be used.

[0012] High-temperature accumulators are characterized by their operation above room temperature, typically in a temperature range of 250–350 °C. The separator exhibits increased ionic conductivity in these conditions. For accumulators operating at temperatures below 200 °C, rubber seals could be used, and the stack could be mechanically clamped if necessary. This would eliminate the need for a metal / ceramic composite and would better protect the ceramic / ceramic composite against aggressive media that are the root cause of the problem.

[0013] To increase the power density of a high-temperature battery (e.g., made of Na / NiCl₂ or Na / S), the ohmic resistance of the individual cell components must be reduced, and their weight must be decreased. The ohmic cell resistance of such a battery is also determined by the distance between the cathode electrode and the separator, and thus by the thickness of the cathode material. With increasing distance, the transport of sodium ions is inhibited, while the diffusion front migrates from the separator into the interior, causing the electrons to travel a longer distance. The contact resistances between one metal particle and the next also limit the power output. The aspect ratio of cathode volume to electrode and separator surface area, in conjunction with the cathode resistance, plays a crucial role in determining the maximum possible charging and discharging currents.

[0014] A tubular cell geometry is characterized by a separator formed by a tube closed at one end, with a cross-sectional area or diameter that is generally smaller than the tube length along the cell's central axis. The cathode electrode is located in the center. If it is larger, the electrical storage capacity is reduced by the displaced volume.

[0015] In a planar cell geometry, the separator is flat to saucer-shaped / cup-like, with a cross-sectional area or diameter that is usually larger than the depth along the central axis of the cell.

[0016] This implies that a tubular separator has a significantly smaller cathode-side electrode surface area relative to the cathode volume compared to a planar separator.

[0017] In cell arrangements formed from several tubular cells, these are arranged within a common shell in a matrix.

[0018] In cell arrangements formed from several planar cells, these are arranged within a common casing in a stack and are also referred to as a cell stack.

[0019] The difficulties that arise in the design and dimensioning of cells and cell arrangements formed from them are explained below using the example of a high-temperature accumulator formed by a Na / NiCl2 cell or a cell arrangement formed from Na / NiCl2 cells.

[0020] If, contrary to common practice, the cell or cell array, and thus the sodium ion-conducting separator, does not have a tubular shape (where the separator wall thickness is not much less than 1.5 mm due to manufacturing constraints), but rather a planar shape, the separator's weight can be significantly reduced due to the smaller wall thickness and larger surface area relative to the cathode volume. The separator's resistance decreases proportionally with its wall thickness, and therefore the reduced wall thickness also leads to a decrease in the separator's strength. During charging, the cathode volume decreases due to the removal of sodium ions, forming NiCl₂. This, in turn, reduces the internal volume of the anode compartment due to sodium deposition, provided the anode compartment cannot expand. Thus, during the charging process, a negative pressure develops in the cathode compartment and a positive pressure in the anode compartment.If these pressure differences are not compensated, a very thin separator (depending on the diameter / wall thickness ratio of e.g. 65 mm / 0.5 mm) will not be able to withstand these stresses permanently.

[0021] Another problem arises from the stacked cell arrangement, where the cells are stacked on top of each other. Since the pressure increase in the anode compartment and the pressure drop in the cathode compartment during the charging process are generally not equal, a typical bipolar design, in which the anode-side and cathode-side electrodes of two adjacent cells are formed by a single bipolar electrode that cannot adequately compensate for the pressure difference, leads to a corresponding stress on the separator.

[0022] Commercially available high-temperature accumulators based on sodium / metal chloride are currently marketed as tubular cell arrangements, in which the separator, made of sodium β-aluminate, is designed as a hollow geometry (e.g., tube-shaped) closed at one end. Due to the aspect ratio of length to diameter of a tubular cell, the chemical substances (e.g., metallic sodium, NaAlCl4), taking into account a corresponding inclination angle of the cell's central axis relative to the horizon, do not have direct contact with a bonding zone formed between the separator and the insulator, but only their vapor phase. In high-temperature accumulators based on Na / NiCl2 or Na / S, the separator, e.g., made of sodium β-aluminate, is joined to an insulator, e.g.,...A corundum ring (for strength reasons) is used as the solder, which, although it has a coefficient of thermal expansion adapted to the joining partners, is not resistant to liquid sodium for the intended service life of at least 10 years. While the separator exhibits low sodium ion conductivity at room temperature, but good conductivity above 200°C, the high temperature inevitably leads to an increasing corrosion-induced decomposition process of the glass solder if the sodium has direct contact with the joining zone and thus with the glass solder.

[0023] The resistance in the cathode compartment increases towards the end of the discharge process, regardless of the cell geometry, due to the growing diffusion front that propagates from the separator to the cathode-side electrode in the cathode, up to a factor of six. Consequently, a planar cell, with a correspondingly relatively thin cathode mixture compared to the diameter of the separator, can exhibit lower resistance, especially with regard to deep discharge, compared to a tubular cell. As a result, the planar cell can be charged and discharged with higher currents.

[0024] In order to make the separator as thin as possible without exposing it to the risk of destruction, various measures are taken in the prior art.

[0025] In principle, the strength of a separator produced by sintering can be increased by adding additives, e.g. ZrO2, which, however, inevitably leads to a reduction in sodium ion conductivity.

[0026] A planar Na / S cell is known from EP 0 451 610 A1. This patent also describes the fundamental geometric distinction between planar and tubular cells, which are cylindrical in this case. The cell comprises a container made of electrically non-conductive material, e.g., ceramic, in particular alpha aluminum oxide, which is essentially a straight cylinder with a short length relative to its diameter. An inwardly directed projection is formed on the inner circumference of the container. A ceramic electrolyte, which also acts as a separator, is attached to this projection and sealed against it by means of a glass solder or an intermediate layer. Various measures are proposed to ensure that this separator can be made as thin as possible without being damaged by the pressure or stresses generated during normal use.

[0027] One possible solution would be to arrange a separately manufactured mesh-like support structure across the cross-section of the container.

[0028] A second possibility is the formation of ribs on the separator. In both cases, the resistance of the separator is inevitably increased.

[0029] According to a third possibility, the filler material in the anode space should be designed with a stiffness that provides mechanical support for the separator.

[0030] No measures are taken to protect the joining zones, i.e., the areas where the separator is connected to the insulator or the insulator to the electrodes, either directly or indirectly, e.g., via glass solder or an intermediate layer, from the effects of chemical substances located in the cathode and anode compartments.

[0031] US Patent 3,783,024 A describes a planar alkali metal / sulfur cell with a planar β-aluminate separator and a series connection of such cells, which does not differ significantly in geometry from a previously mentioned cell. The electrodes are flexible, allowing them to deform with pressure changes in the adjacent spaces, thus compensating for volume changes and the resulting pressure changes acting on the separator. Again, no measures are taken to protect the joining zones from the chemical substances.

[0032] WO 2012 / 031346 A1 proposes a dome-shaped cell and a cell system formed from it, the geometry of which is determined by the dome shape of the solid electrolyte. Advantageously, its surface should be corrugated or ribbed. The cell components, arranged in series with the electrolyte and possessing a defined geometry, are also dome-shaped, so that, spaced apart from one another, they form spaces in conjunction with a cylindrical cell body, each representing an anode and a cathode compartment. Similar to the previously mentioned solutions, the interfaces between the cell components, particularly the electrolyte with its ceramic ring acting as cell shell and insulator, are not protected from the chemical substances present in the anode compartment. It is proposed here to manufacture the glass seal between the ceramic ring and the electrolyte from a glass material exhibiting high corrosion resistance.

[0033] According to US 2012 / 0088133 A1, venting is provided in the anode and cathode compartments in the form of openings to reduce the load on the solid electrolyte. The question remains how to prevent the leakage of chemical substances and, if necessary, how to avoid contact between these substances and the joining zones.

[0034] All the aforementioned cells have in common that the formation of their cathode and / or anode compartments, each bounded on one side by a separator, involves a ring-shaped insulator that, together with the separator, forms a bonding zone exposed to the chemical substances present in the cathode and / or anode compartment. Materials typically used for joining ceramic / ceramic composites, such as glass solder, are not permanently corrosion-resistant for more than 10-15 years, for example, against liquid sodium. Therefore, the lifespan of the cells is also limited by the durability of these bonding zones.

[0035] US patent 2013 / 0108912 A1 discloses a stack design for a sodium-nickel chloride battery with planar cells, in which a separator (referred to there as the base layer) and adjacent electrodes (referred to there as bipolar layers) are connected via an insulator unit (referred to there as seals). The electrodes and the separator have a rotationally symmetrical, disc-shaped form, which, due to gravity, keeps the anode and cathode materials located between them away from the insulator unit. This is intended to reduce or eliminate the possibility of the anode or cathode material coming into contact with the seals (insulator unit). A disadvantage of this design is that preventing contact requires a specific orientation of the battery.

[0036] The invention is based on the objective of creating a high-temperature accumulator with at least one planar cell in which joining zones formed between the separator and other components of the cell are permanently protected from chemical substances in solid or liquid state, which are located within the cathode or anode space, regardless of the spatial orientation of the high-temperature accumulator.

[0037] The problem is solved for a high-temperature accumulator with at least one planar cell according to claim 1. Advantageous embodiments are described in the dependent claims.

[0038] The invention will now be explained in more detail using exemplary embodiments and the accompanying drawings. These drawings show: Fig. 1 a sectional view of a high-temperature accumulator with three cells according to a first embodiment, in which the seal is formed by a first groove, Fig. 2 a sectional view of a high-temperature accumulator with seven cells according to a second embodiment, in which the seal is formed by a first and a second bead, Fig. 3 a sectional view of a high-temperature accumulator according to the invention with seven cells according to a third embodiment, in which the seal is formed by a sealing ring, Fig. 4 a sectional view of a cell according to a fourth embodiment, in which the seal borders the electrode edge, Fig. 5 a sectional view of a cell according to a fifth embodiment, in which the seal is formed by an edge on the anode-side electrode, and Fig. 6 a sectional view of a cell according to a sixth embodiment, in which the seal is formed by an edge on the separator.

[0039] A high-temperature accumulator according to the invention comprises at least one planar cell 1, as described below with reference to Fig. 1 is described. Several such cells of the same dimensions 1 can be arranged one above the other along a central axis 1.1 and spaced apart from each other by a distance a, forming a cell arrangement in the form of a cell stack.

[0040] A cell 1 according to the invention consists of an anode-side electrode 2, an adjacent anode compartment 3, a cathode-side electrode 6, an adjacent cathode compartment 5, and a separator 4, which electrically insulates the anode compartment 3 and the cathode compartment 5, but allows the electrolyte to pass through. Furthermore, the cell 1 has an insulator unit 7, which is formed by a ring or several ring-shaped segments and forms a first joining zone A with the anode-side electrode 2 and a second joining zone B with the separator 4. A third joining zone C is formed between the separator 4 and the cathode-side electrode 6. To match the coefficients of thermal expansion of the separator 4, e.g., made of sodium β-aluminate, and the insulator unit 7, e.g., B. made of corundum, the separator 4 and the insulator unit 7 are connected to each other in the second joining zone B via a glass solder or an intermediate layer.In particular, this second joining zone B is protected by a cell 1 construction according to the invention from the effects of chemical substances in solid or liquid form located in the cell 1.

[0041] The anode-side electrode 2 has a rotationally symmetrical, disc- or cup-shaped form, with a round electrode base 2.1 and an electrode wall 2.2 that transitions into an electrode rim 2.3 parallel to the electrode base 2.1. The electrode wall 2.2 forms an electrode wall angle α2 with the electrode base 2.1. The electrode wall angle α2 is generally greater than 90° and less than 180°, preferably around 135°, but in a special embodiment it can also be 90° or even less. Preferably, an inwardly directed circumferential first groove 2.2.1 is incorporated into the electrode wall 2.2 (see figure). Fig. 2) The anode-side electrode 2 is made of metal, e.g., stainless steel 1.4003 or an iron-nickel alloy, and preferably as a pressed piece. Due to its additional function, the shape of the anode-side electrode 2 forms the sodium reservoir.

[0042] The separator 4 has essentially the same geometric shape as the anode-side electrode 2, with a round separator base 4.1 and a separator wall 4.2 that transitions into a separator rim 4.3 parallel to the separator base 4.1. The separator wall 4.2 forms a separator wall angle α4 with the separator base 4.1. The separator wall angle α4 is generally greater than 90° and less than 180°, preferably around 135°, but can also be 90° in a special embodiment. The separator 4 is preferably made of β-aluminate. Preferably, at least the electrode base 2.1 and the separator base 4.1 are of the same dimensions. The separator 4 and the anode-side electrode 2 are arranged in relation to each other in a manner comparable to stacked plates, with the electrode edge 2.3 and the separator edge 4.3 lying against each other indirectly via the insulator unit 7.

[0043] The ring or ring segments of the insulator unit 7 preferably have a stepped height, namely a first height h1 between the separator edge 4.3 and the electrode edge 2.3 of the anode-side electrode 2, and a second height h2 between the two electrodes 6, 2. The first height h1, in conjunction with the dimensions of the electrode wall 2.2, determined by the electrode wall length l2 and the electrode wall angle α2, and the separator wall 4.2, determined by the separator wall length l4 and the separator wall angle α4, determines the distance of the electrode base 2.1 from the separator base 4.1, which in turn is crucial for the volume of the anode compartment 3. The axes of symmetry of the separator 4 and the anode-side electrode 2 coincide with the central axis 1.1 of the cell 1.

[0044] It is essential to the invention that the electrode wall 2.2 and the separator wall 4.2 are electrically insulated from each other and sealed by a gasket. The gasket can be formed by the geometry of the electrode wall 2.2 and / or the separator wall 4.2, for example, advantageously by a first groove 2.2.1 formed in the electrode wall 2.2 or by a discrete component, such as an interposed sealing ring 9. Due to the gasket acting as a barrier, a closed space is created between these components, which constitutes the anode space 3. The anode space 3 is formed by the electrode base 2.1, the separator base 4.1, and adjacent areas of the electrode wall 2.2, the separator wall 4.2, and the gasket. The first height h1 of the insulator unit 7 and the gasket are matched to each other such that the anode space 3 is sealed.

[0045] This means that, unlike all previously known cells of the same type 1, the insulator unit 7 is not involved in the boundary of the anode compartment 3. Consequently, the joining zones A, B and C are also outside the anode compartment 3 and cannot come into contact with liquid or solid chemical substances located in the anode compartment 3.

[0046] The shape of the separator 4 determines, on the one hand, the boundary of the anode compartment 3 and, on the other hand, the shape and volume of the cathode compartment 5, which is hermetically sealed by the cathode-side electrode 6. Advantageously, the cathode-side electrode 6, which is formed by a flat metal sheet (metal disc), does not rest against the separator edge 4.3 or does so without stress and is connected to the insulator unit 7, e.g., by ultrasonic, inductive, or furnace soldering, or possibly also by thermocompression welding.

[0047] To avoid mechanical stress on the separator 4, pressure equalization between the anode compartment 3 and the cathode compartment 5 does not occur directly via the separator 4, but rather between the anode compartment 3 and the cathode compartment 5, respectively, and the space surrounding the cell 1. This space can be the atmosphere or a space formed by a housing. The pressure change is counteracted by the deformation of the electrodes 2 and 6, which alters the volume of the anode compartment 3 and the cathode compartment 5. For this purpose, the electrodes 2 and 6 are designed to be correspondingly thin. The mechanical stress on the separator 4 is thus reduced to a minimum.

[0048] To allow the electrodes 2, 6 within a cell stack to deform unhindered, the individual cells 1 forming a cell stack are in contact with each other only via their edge regions through a spacer 8. The directly opposite electrodes 2, 6 of adjacent cells maintain a distance 'a' from each other, which does not become zero even with maximum deformation of the electrodes 2, 6. An electrical connection between the cells 1 can also be established via the spacer 8. The spacer 8 can be rigid, e.g., formed by at least two spacer plates, angle brackets, bolts, or a spacer ring. It can also be formed by at least one elastic, high-temperature-resistant sealing ring 9, e.g., made of mica or graphite, optionally in combination with thin metal foils.When using non-electrically conductive sealing rings 9, additional electrical connections are required. In the case of a closed ring shape of the spacer 8, it is provided with openings for pressure equalization.

[0049] According to a first embodiment, as in Fig. As shown in Figure 1 and already mentioned as advantageous, the seal is formed by a first bead 2.2.1 formed on the electrode wall 2.2. During the assembly of the cell 1, in which the anode-side electrode edge 2.3 and the separator edge 4.3 are fixed to each other via the insulator unit 7 at a distance equal to the first height h1 of the insulator unit 7, the first bead 2.2.1 is pressed against the separator wall 4.2, thereby forcefully connecting the separator wall 4.2 and the electrode wall 2.2 and forming a closed, sealed anode chamber 3.

[0050] Alternatively or additionally, as in Fig. As shown in a second embodiment, a second groove 4.2.1 can be formed on the separator wall 4.2. This creates a larger contact area between the separator 4 and the anode-side electrode 2.

[0051] In the aforementioned embodiments, the separator wall angle α4 and the electrode wall angle α2 preferably have the same value, preferably around 135°. The larger the electrode wall angle α2 and the separator wall angle α4 are, the more favorable the force distribution for the seal. However, this increases the installation space in the radial direction without advantageously increasing the anode space 3 or the effective separator area of ​​the separator 4.

[0052] In a third embodiment, shown in Fig. 3, the seal is formed by a discretely manufactured sealing ring 9. Its cross-section is advantageously conical, and the separator wall angle α4 and the electrode wall angle α2 have an angle difference adapted to the conical angle of the sealing ring 9. After assembly of the cell 1, the sealing ring 9 is force-fitted between the electrode wall 2.2 and the separator wall 4.2.

[0053] An advantage of this third embodiment is that a sealing ring 9 can bridge and thus seal a significantly larger gap between the electrode wall 2.2 and the separator wall 4.2 than a first groove 2.2.1, which, due to manufacturing constraints, cannot exceed a maximum depth without causing material constrictions that could compromise stability. A material resistant to the chemical substances in the cell 1 is used for such a sealing ring 9.

[0054] With fundamentally identical dimensions of the separator 4 and the anode-side electrode 2, and thus maintaining the size of the cell 1, the effective area of ​​the separator 4, i.e., the area directly adjacent to the anode chamber 3, can be enlarged compared to the previously described embodiments if the seal is arranged adjacent to the electrode edge 2.3. This means that, in addition to the separator base 4.1, almost the entire separator wall 4.2 is available as an effective area.

[0055] A corresponding fourth embodiment is described in Fig. Figure 4 shows that, by way of example, the seal was formed here by a first bead 2.2.1 formed on the electrode wall 2.2.

[0056] In a fifth embodiment, shown in Fig. 5, the seal is formed by an edge on the anode-side electrode 2. The electrode wall angle α2 is preferably equal to or less than 90°.

[0057] At the in Fig. In the sixth embodiment shown in Figure 6, the seal is formed by an edge on the separator 4. The separator wall angle α4 is preferably equal to or less than 90°.

[0058] In terms of manufacturing technology, the last two embodiments mentioned are the simplest versions of a cell 1 according to the invention.

[0059] Regardless of the illustrated embodiments of a cell 1, which differ in particular in the design of the seal, the electrode base 2.1 can be flat or provided with first beads 2.2.1 arranged coaxially to each other, which increase the stiffness so that the thickness of the electrode base 2.1 can be reduced. The spacing of the coaxial beads can be used to influence where the deformations begin.

[0060] If the seal is not a discrete component but is formed on the separator 4 and / or the anode-side electrode 2, it is provided with an insulating layer or a coating at least in the resulting contact area. If the seal is a discrete component, it is made of an electrically insulating material.

[0061] In all embodiments, except for the third embodiment, illustrated in Fig. 3. The insulator unit 7 is formed by a stepped ring or such ring segments, that is, one end face facing the cathode-side electrode 6 is divided into an outer annular surface and a recessed inner annular surface adjacent to the inner circumferential surface of the ring. The separator rim 4.3 is placed on the inner annular surface. The outer annular surface has a second height h2 at one end face facing the anode-side electrode 2, which is at least equal to the sum of the first height h1 and the thickness of the separator wall 4.2. Thus, the joining zones A, B, and C are also excluded from the anode space 3.

[0062] As demonstrated by Fig.As shown in Figure 3, in a third embodiment the insulator unit 7 is formed by a non-stepped ring or such ring segments. Instead of the step, a metal ring 6.1 is attached to the end face facing the cathode-side electrode 6, which forms a continuous end face. This ring is recessed towards the inner circumferential surface, leaving an annular area on the end face adjacent to the inner circumferential surface, to which the separator rim 4.3 is glazed using glass solder. The use of an additional metal ring 6.1 with a third height h3 not only results in a simpler geometry of the ring, whose end faces in this case represent identical planar surfaces, but also allows, during the assembly of a cell 1, the metal ring 6.1 to be attached first.The anode-side electrode 2 and the anode-side electrode 2 are soldered onto the ring, then the cathode chamber 5 is filled with the cathode material, and finally the cathode-side electrode 6 can be welded onto the metal ring 6.1. Preferably, the metal ring 6.1 and the cathode-side electrode 6 have the same outer diameter, which should be selected so that the heat input during welding at the circumference is not too high for either the cathode material introduced into the cathode chamber 5 or the third joining zone C. Advantageously, the outer diameter of the metal ring 6.1 and the cathode-side electrode 6 extends beyond the insulator unit 7, so that the weld zone formed between them has the greatest possible distance to the cathode chamber 5.This comparatively increases the path for heat conduction from the weld zone to the second joining zone B and to the cathode material, thus further reducing the thermal stress on the cathode material and the metal / ceramic joints during the assembly of a cell 1. Advantageously, the spacers 8 and the anode-side electrode 2 are also welded as far away as possible from the cathode chamber 5 in order to minimize the resulting heat input.

[0063] Compared to tubular designs, planar construction opens up new possibilities in applications where weight and installation space are limited. The integration of a planar high-temperature battery as an energy storage device in the field of electromobility (e-mobility) could therefore also be achieved in unused areas of a vehicle, e.g., in the floor, or even as a rooftop installation on buses. Reference symbol list 1 cell 1.1 Center axis (of cell 1) 2 anode-side electrode 2.1 Electrode base 2.2 Electrode wall 2.2.1 first groove 2.3 Electrode edge α2 electrode wall angle l2 electrode wall length 3 anode compartment 4 Separator 4.1 Separator base 4.2 Separator wall 4.2.1 second groove 4.3 Separator edge α4 separator wall angle l4 Separator wall length 5 Cathode space 6 cathode-side electrode 6.1 Metal ring 7 Insulator unit 8 spacers 9 Sealing ring a distance h1 first height h2 second height h3 third height A first joining zone B second joining zone C third joining zone

Claims

[1] High-temperature accumulator with at least one planar cell (1) having an anode-side electrode (2), a separator (4) and a cathode-side electrode (6) arranged one behind the other along a central axis (1.1), wherein an anode compartment (3) is formed between the anode-side electrode (2) and the separator (4) and a cathode compartment (5) is formed between the separator (4) and the cathode-side electrode (6), and an insulator unit (7) is provided which mechanically connects the anode-side electrode (2) and the cathode-side electrode (6) and which is indirectly connected to the separator (4) in a joining zone (B) via a solder or intermediate layers, wherein the anode-side electrode (2) has a disc-shaped form rotationally symmetrical to the central axis (1.1), with an electrode base (2.1) and an electrode wall (2.2) which are divided into a Electrode base (2.1) transitions to parallel electrode edge (2.3), with the electrode wall (2.2) encloses an electrode wall angle (α2) with the electrode base (2.1), and the separator (4) has a shape rotationally symmetrical to the central axis (1.1), with a separator base (4.1) and a separator wall (4.2) which transitions into a separator rim (4.3) parallel to the separator base (4.1), wherein the separator wall (4.2) encloses a separator wall angle (α4) with the separator base (4.1), wherein the electrode rim (2.3) and the separator rim (4.3) are indirectly connected to each other via the insulator unit (7), . characterized by, that the separator wall (4.2) and the electrode wall (2.2) are electrically insulated from each other and sealed by at least one barrier seal, whereby the anode space (3) is limited by the anode-side electrode (2), the separator (4) and the seal, so that the joining zone (B) lies outside the anode space (3) and cannot come into contact with liquid or solid chemical substances located in the anode space (3). [2] High-temperature accumulator according to claim 1 characterized by, that the separator wall angle (α4) and the electrode wall angle (α2) are greater than 90° and less than 180° and the separator wall angle (α4) is greater than or equal to the electrode wall angle (α2) and a first bead (2.2.1) is formed on the electrode wall (2.2) or a second bead (4.2.1) is formed on the separator wall (4.2), wherein the first bead (2.2.1) or the second bead (4.2.1) represents at least one seal and is covered with an electrically insulating layer or provided with a support. [3] High-temperature accumulator according to claim 1 characterized by, that the separator wall angle (α4) and the electrode wall angle (α2) are greater than 90° and less than 180° and the separator wall angle (α4) is equal to the electrode wall angle (α2) and a first bead (2.2.1) is formed on the electrode wall (2.2) and a second bead (4.2.1) is formed on the separator wall (4.2), wherein the first bead (2.2.1) and the second bead (4.2.1) each represent a seal and are covered with an electrically insulating layer or provided with a support. [4] High-temperature accumulator according to claim 1 characterized by , that the separator wall angle (α4) is larger than the electrode wall angle (α2) and the seal is formed by a conical sealing ring (9) made of an electrically insulating material. [5] High-temperature accumulator according to claim 1 characterized by, that the electrode wall angle (α2) is less than 90°, so that an edge is formed between the electrode wall (2.2) and the electrode edge (2.3), which is covered with an electrically insulating layer or provided with a support and represents the seal, and the separator wall angle (α4) is greater than 90°. [6] High-temperature accumulator according to any one of claims 1 to 4, characterized by , that the seal borders the electrode edge (2.3). [7] High-temperature accumulator with at least two cells (1) according to claim 1, characterized by , that these are arranged one behind the other at a distance (a) from each other, wherein their central axes (1.1) coincide, so that each adjacent electrode (2, 6) can deform unhindered within the distance (a).

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