Battery cell for the modular construction of a rechargeable metal-air battery, holding device for a battery cell and battery module with multiple battery cells

Abstract

Battery cell (10) for the modular construction of a rechargeable metal-air battery, in particular a zinc-air battery, comprising a metal electrode (12), at least one foil-like electrode element (14) for forming an air counter electrode (16) of the metal electrode (12), and a holding device (18) comprising a frame-like base body (20) and at least one strut structure (22) arranged in the frame-like base body (20) with several struts (24, 26) extending in the frame plane spanned by the base body (20) for mechanical support of the at least one foil-like electrode element (14), wherein the metal electrode (12) as well as the at least one electrode element (14) are enclosed adjacently spaced apart from each other in the frame-like base body (20), and at least one first of the struts (24) of the strut structure (22) extends transversely to at least one second of the struts (26) of this strut structure (22).wherein the strut structure (22) is formed in two parts and in the first part of the strut structure (22) between the foil-like electrode element (14) and the metal electrode (12) only the at least one first strut (24) of the strut structure (22) is arranged, which extends from a first frame part of the base body (20) to form the top (28) of the holding device (18) to a second frame part of the base body (20) to form the bottom (30) of the holding device (18) such that a gas component present in the electrolyte can escape as gas bubbles towards the top of the battery cell (10) and in the second part of the strut structure (22) on the side (32) of the foil-like electrode element (14) facing away from the metal electrode (12) only the at least one second strut (26) of the strut structure (22) is arranged.

Description

[0001] The invention relates to a battery cell for the modular construction of a rechargeable metal-air battery, in particular a zinc-air battery, with (i) a metal electrode, (ii) at least one foil-like electrode element for forming an air counter electrode of the metal electrode and (iii) a holding device which has a frame-like base body and at least one strut structure arranged in the frame-like base body with a plurality of struts running in the frame plane spanned by the base body for mechanically supporting the foil-like electrode element, wherein the metal electrode as well as the at least one electrode element are enclosed adjacent to one another in the frame-like base body at a distance from one another and at least a first of the struts of the strut structure runs transversely to at least a second of the struts of this strut structure.The invention further relates to a holding device for such a battery cell and a battery module of a metal-air battery with several battery cells.

[0002] Document EP 0 673 076 A1 shows a corresponding prismatic battery cell for the modular construction of a rechargeable zinc-air battery, comprising a central zinc electrode, two foil-like electrode elements surrounding the zinc electrode on both sides to form air counterelectrodes, and a holding device comprising a two-part frame-like base body and two strut structures arranged in the frame-like base body, each with a plurality of struts extending in the frame plane spanned by the base body for mechanically supporting the respective foil-like electrode element. The zinc electrode and the two electrode elements are enclosed in the frame-like base body at a distance from one another.At least a first of the struts of each of the strut structures runs transversely to at least a second of the struts of these lattice-like strut structures, wherein these lattice-like strut structures are each arranged outside the electrode element to be supported. An electrolyte, such as potassium hydroxide, is located between the zinc electrode and the foil-like electrode elements. Each of the foil-like electrode elements is sufficiently electrically conductive, permeable to gases, but impermeable to liquids. The outer side of the respective electrode element facing away from the zinc electrode is surrounded by air or another gas containing oxygen. The publication also mentions a modular zinc-air battery with several of these battery cells.The document US 2010 / 0173206 A1 shows a very similar battery cell in which both first and second struts of the strut structure are arranged both between the foil-like electrode element and the metal electrode and on the side of the foil-like electrode element facing away from the metal electrode.

[0003] Further battery structures with strut structures are shown in US 2010 / 0 310 967 A1 and in WO 2004 / 008 563 A2.

[0004] One application for such modular rechargeable batteries is as traction batteries for electric or hybrid vehicles. Another application is as intermediate storage for electrical energy in solar and wind turbine systems. Currently, lithium-ion batteries are primarily intended for these applications.

[0005] To achieve the electrical voltages required for the applications, a relatively large number of battery cells must be interconnected to form the traction battery (the battery system), so a modular design is usually required, regardless of the battery type. In this case, several battery cells are interconnected in battery modules with manageable parameters (size, weight, total voltage, etc.), which in turn are electrically interconnected to form the battery system, the corresponding overall battery.

[0006] In the cells of some battery types, such as metal-air batteries, periodic cell deformation occurs during charge and discharge cycles, known as "cell breathing." If the cells are not sufficiently supported during the return to their original structure and position, permanent shape or even structural changes—for example, in the electrode material—can occur, which limits the battery's service life. To avoid or at least suppress such shape and structural changes, prismatic cells are packed into a stack in a battery module, and this cell stack is pre-tensioned using a tensioning device.

[0007] The publication DE 10 2010 031 641 A1 shows a corresponding battery module. In this battery module, the clamping device is reduced to a retaining band framing the cell stack with a leaf spring-like spring plate, which is arranged at one end of the stack between the stack and the retaining band surrounding the stack.

[0008] However, such pre-tensioning is problematic in metal-air batteries because the liquid electrolyte, which can - at least temporarily - also contain a gas component, is located between the metal electrode and the foil-like electrode element forming the counter electrode.

[0009] It is the object of the invention to provide measures that make it possible to provide a long-life, rechargeable metal-air battery constructed modularly from battery cells.

[0010] In the battery cell according to the invention for the modular construction of a rechargeable metal-air battery, it is provided that the at least one first strut of the strut structure is arranged between the foil-like electrode element and the metal electrode and extends from a first frame part of the base body for forming the upper side of the holding device (frame device) to a second frame part of the base body for forming the underside of the holding device, and the at least one second strut of the strut structure is arranged on the side of the foil-like electrode element facing away from the metal electrode. The arrangement of the struts on both sides of the at least one foil-like electrode element provides better support.At the same time, the at least one first strut spatially separates the metal electrode clearly from the foil-like electrode element and defines a corresponding distance between the metal electrode and the electrode element for accommodating an electrolyte of the cell. Since the at least one first strut extends from the first frame part of the base body, which forms the upper side, to the second frame part of the base body, which forms the underside of the holding device, a gas component present in the electrolyte can escape as gas bubbles towards the upper side of the battery cell. Furthermore, the metal electrode, for example the zinc electrode of a cell for a rechargeable zinc-air battery, undergoes a pear-shaped deformation over several charge-discharge cycles. This deformation is advantageously limited by the at least one first strut.

[0011] In a battery cell for the modular construction of a rechargeable zinc-air battery, the metal electrode is a zinc electrode. The holding device is made of an electrically insulating material or at least comprises a correspondingly electrically insulating material. The material is preferably plastic. The aforementioned components of the holding device, i.e., the frame-like base body and strut structure, are to be understood as functional units and therefore do not necessarily define spatial-structural boundaries within the holding device. In principle, the battery cell is not limited to a specific geometry. However, the battery cell is preferably designed as a prismatic battery cell. The active area of ​​the at least one foil-like (membrane-like) electrode element is preferably ≥ 10,000 mm 2 .

[0012] According to a preferred embodiment of the invention, it is provided that the at least one first strut has a depth extension T ≥ 3 mm, particularly preferably T ≥ 4 mm, over its entire length, namely an extension which is greater than gas bubbles occurring in the electrolyte between the foil-like electrode element and the metal electrode during operation of the battery cell.

[0013] According to a further preferred embodiment of the invention, the at least one strut structure comprises a plurality of first struts and a plurality of second struts. The struts are distributed, in particular, evenly over the surface of the foil-like electrode element. Particularly preferably, the at least one strut structure comprises two first struts and three second struts.

[0014] According to yet another preferred embodiment of the invention, it is provided that the at least one first strut is connected in one piece to the frame-like base body.

[0015] In a preferred embodiment of the invention, the holding device comprises at least one support frame that can be fastened in / on the base body, preferably by clipping, and that supports the second struts of one strut structure or of one of the strut structures. In this embodiment, the foil-like electrode element can be simply inserted into the frame-like base body, and the support frame with the second struts can be simply placed on the foil-like electrode element.

[0016] In a further preferred embodiment of the invention, the battery cell comprises two foil-like electrode elements surrounding the metal electrode on both sides to form air counterelectrodes of the metal electrode. In addition to the frame-like base body, the holding device comprises two strut structures arranged in the frame-like base body, each with a plurality of struts extending in the frame plane spanned by the base body for mechanically supporting the respective foil-like electrode element.

[0017] According to a preferred embodiment of the invention, the holding device has a removable cover on one of its sides, preferably on its top. Removing the cover allows the metal electrode (anode) to be easily replaced. The cover, in particular, has openings for connecting the electrodes (the metal electrode and the at least one air electrode).

[0018] According to a further preferred embodiment of the invention, the holding device has a liquid-impermeable gas outlet on its upper side. This gas outlet allows the gas from the rising gas bubbles in the electrolyte to escape. If the holding device has the lid on its upper side, the gas outlet is preferably formed in the lid.

[0019] Finally, it is advantageously provided that the holding device has at least one fluid connection for supplying and / or removing electrolyte. Preferably, one connection for supplying and one connection for removing the electrolyte are provided.

[0020] The invention further relates to a holding device for a battery cell having at least one foil-like electrode element for forming an air electrode and a metal electrode, in particular an above-mentioned battery cell, wherein the holding device has a frame-like base body and at least one strut structure arranged in the frame-like base body with a plurality of struts running in the frame plane spanned by the base body for mechanically supporting the foil-like electrode element, wherein the metal electrode as well as the at least one electrode element can be enclosed adjacent to one another in the frame-like base body at a distance from one another and at least a first of the struts of the strut structure runs transversely to at least a second of the struts of this strut structure.According to the invention, it is provided that the at least one first strut of the strut structure can be arranged between the foil-like electrode element and the metal electrode and extends from a first frame part of the base body for forming the upper side of the holding device to a second frame part of the base body for forming the underside of the holding device and the at least one second strut of the strut structure can be arranged on the side of the foil-like electrode element facing away from the metal electrode.

[0021] Finally, the invention relates to a battery module of a metal-air battery, comprising (i) an array of battery cells, in particular a stack of prismatic battery cells, and (ii) a clamping device for clamping the array of battery cells in this clamping device. According to the invention, the battery cells are designed as a plurality of the battery cells described above.

[0022] The invention will now be explained by way of example with reference to the accompanying drawings using preferred embodiments, wherein the features presented below may represent an aspect of the invention both individually and in combination. They show: Fig. 1: a battery cell of a zinc-air battery according to a preferred embodiment of the invention, Fig. 2: another view of the Fig. 1 battery cell shown, Fig. 3: a sectional view through the battery cell along the Fig. 2 shown section line A - A, Fig. 4: a plan view of the top of the Fig. 1 - 3 shown battery cell, Fig. 5: a base frame of a holding device for holding the electrodes of the battery cell, Fig. 6: a cover of the holding device with recesses for the connections of the electrodes, Fig. 7: a support frame of the holding device and Fig. 8: The complete holding device of the Fig. Battery cell shown in 1 - 4.

[0023] The invention is explained below using the example of a zinc-air battery cell 10, although all aspects of the invention can be applied to the battery cells of other metal-air batteries. The only essential difference is that the zinc electrode 12 is replaced with a different metal electrode 12.

[0024] The Fig. Figure 1 shows a battery cell 10 for the modular construction of a rechargeable zinc-air battery. The battery cell 10 shown is designed as a prismatic battery cell. This cell 10 comprises a Fig. 3 shows a central zinc electrode 12 shown in detail, two foil-like (or membrane-like) electrode elements 14 surrounding the zinc electrode 12 on both sides to form air counter electrodes 16 and a holding device 18. In Fig. 1 only one connection of the central zinc electrode 12, two connections of the two air counter electrodes 16 and parts of one of the electrode elements 14 are visible.

[0025] The holding device 18 can be functionally divided into two parts: a frame-like base body 20 and two strut structures 22 arranged in the frame-like base body 20, each with a plurality of first and second struts 24, 26 extending in the frame plane spanned by the base body 20 for mechanically supporting the respective foil-like electrode element 14. The first struts 24 of each of the strut structures 22 are aligned transversely to the second struts 26 of the strut structures. Each of the strut structures 22 is formed in two parts, with only the first struts 24 being arranged in the first part of each of the strut structures, and only the second struts 26 being arranged in the second part.The first part of the strut structure 22 with the first struts 24 is arranged between the respectively associated foil-like electrode element 14 and the metal electrode 12, wherein the first struts 24 extend (vertically) from a first part of the base body 20 to form an upper side 28 of the holding device 18 to a second part of the base body 20 to form an underside 30 of the holding device 18. However, this first part of the strut structures is only shown in the . Fig. 6 and Fig. 8 recognizable and in Fig. 1 not shown. The second part of each of the strut structures 22 with the second struts 26 (part of which Fig. 1) is arranged on the respective outer side 32 of the foil-like electrode elements 14 facing away from the metal electrode 12. Potassium hydroxide is located as the electrolyte 34 between the zinc electrode 12 and the electrode elements 14. Each of the two foil-like electrode elements 14 is sufficiently electrically conductive, permeable to gas, but impermeable to liquid. The outer side 32 of the respective electrode element 14 facing away from the zinc electrode 12 is surrounded by air or another gas containing oxygen. The holding device has a fluid connection 36 for supplying electrolyte in the region of its upper side 28 and a fluid connection 36 for removing electrolyte in the region of its underside 30.

[0026] Before entering the Fig. 5 - 8 the individual components are described from which the holding device 18 shown in the figures is actually composed, the function of the battery cell 10 is to be explained on the basis of the Fig. 2 to 4 will be briefly described again. The Fig. 2 another view of the Fig. 1 in a side view. Here, the holding device 18, the electrical connections of the electrodes 14, 16, one of the electrode elements 14, the horizontally extending second struts 26 of one of the strut structures 22 and the fluid connections 36, 38 are also visible. Furthermore, a section line AA is shown transverse to the plane spanned by the frame-like base body (= image plane of the Fig. 2). The holding device 18 has a removable cover 40 on its upper side 28, which can be clipped onto the rest of the holding device by means of clip structures.

[0027] The Fig. Figure 3 shows a sectional view of the battery cell 10 along this sectional plane AA. The arrangement of the plate-shaped metal electrode 12 and the two air counterelectrodes 16 surrounding the metal electrode on both sides within the holding device 18 is particularly evident. The core of the battery cell 10 is the plate-shaped zinc electrode (as metal electrode 12) centrally accommodated in the holding device 18. This electrode is surrounded by electrolyte 34 located in an interior space 42 of the holding device 18. The interior space 42 is sealed to the outside in a liquid-tight manner, with the exception of the fluid connections 36, 38. The outer boundaries of the interior space 42 are formed partly by components of the holding device 18 itself and partly by the foil-like electrode elements 14, which are gas-permeable but liquid-impermeable. For this purpose, the foil-like electrode elements 14 are glued into the holding device 18 in a liquid-tight manner.The epoxy resin-based adhesive forms seals 44 of the air electrodes. The cover 40 also has a corresponding seal 46. Air or another oxygen-containing gas flows along the outer sides 32 of the electrode elements 14. The air electrodes are formed by the air or the corresponding gas diffusing through the electrode elements 14 to the inner side of the respective electrode element 14, facing the electrolyte 34 and the metal electrode 12 (as the anode), where it forms the air electrode 16 (the corresponding cathode).

[0028] For each of the two strut structures 22, the first part with the first (vertically extending) struts 24 is arranged between the respective foil-like electrode element 14 and the metal electrode 12, while the second part of the respective strut structure 22 with the second (horizontally extending) struts 26 is arranged on the outer side 32 of the foil-like electrode element 14 facing away from the metal electrode 12.

[0029] The Fig. 4 shows a plan view of the top of the Fig. 1-3. The design of the cell cover 40 is particularly visible. Removing the cover 40 allows the metal electrode (anode) 12 to be easily replaced. The cover 40 has, in particular, openings for connecting the electrodes (the metal electrode and the at least one air electrode) 12, 16, as well as a liquid-impermeable gas outlet 48. The gas from the rising gas bubbles can escape from the electrolyte 34 through this gas outlet 48.

[0030] The following function results: The respective arrangement of the struts 24, 26 on both sides of the foil-like electrode elements 14 provides better mechanical support. At the same time, the two first struts 24 per strut structure 22 spatially separate the metal electrode 12 clearly from the foil-like electrode elements 14 and provide a corresponding distance between the metal electrode 12 and the electrode elements 14 for receiving the electrolyte 34 of the cell 10. Since the first struts 24 extend from the first part of the base body 20 forming the top side 28 to the second part of the base body 20 forming the bottom side 30 of the holding device 18, a gas component present in the electrolyte 34 can escape as gas bubbles toward the top side 28 of the battery cell. Furthermore, the metal electrode (e.g., the zinc electrode) 12 undergoes a pear-shaped deformation over several charge-discharge cycles of the rechargeable battery.This deformation is advantageously limited by the first struts 24.

[0031] In Fig. Figure 5 shows the cover 40 of the holding device 18 once again from the inside. Openings 50 for the connections of the electrodes 12, 16 are clearly visible.

[0032] The Fig. 6 shows a base frame 52 for forming the holding device 18. This base frame 52 forms, on the one hand, the respective first part of the strut structures 22 for mechanically supporting the electrode elements 14 and, on the other hand, together with the cover 40, the frame-like base body 20. The base frame 52 has both the fluid connections 36, 38 and alignment structures 54 formed thereon, with which the cells 10 can be precisely aligned when arranged in a stack.

[0033] The Fig. 7 shows a support frame 56 of the holding device 18 with three second struts 26, which can be clipped into / on the base frame 52. This support frame 56 is configured to form a second part of a strut structure 22. This support frame 56 with the second struts 26 allows the corresponding foil-like electrode element 14 to be easily inserted into the base frame 52 (or the frame-like base body 20 formed thereby). Subsequently, the support frame 56 with the second struts 26 is simply placed onto the foil-like electrode element 14 and clipped into place.

[0034] The Fig.8 finally shows the complete holding device 18, i.e. without the electrodes 12, 16 and the electrolyte 34. The holding device 18 is formed by the following components: the base frame 52, the cover 40 and the two support frames 56. The cover 40, together with the base frame 52, forms the frame-like base body 20 for receiving the electrodes 12, 16, while the base frame 52, together with the support frames, forms the two strut structures 22.

[0035] If the cells 10 are packed into a stack within a battery module (not shown) and clamped by means of a clamping device, six force flow lines are created which extend through the entire stack and correspond to six pressure points 58 in each of the battery cells.

Claims

[1] Battery cell (10) for the modular construction of a rechargeable metal-air battery, in particular a zinc-air battery, with a metal electrode (12), at least one foil-like electrode element (14) for forming an air counter-electrode (16) of the metal electrode (12), and a holding device (18) which has a frame-like base body (20) and at least one strut structure (22) arranged in the frame-like base body (20) with a plurality of struts (24, 26) extending in the frame plane spanned by the base body (20) for mechanically supporting the at least one foil-like electrode element (14), wherein the metal electrode (12) as well as the at least one electrode element (14) are enclosed adjacently and spaced apart from one another in the frame-like base body (20), and at least a first of the struts (24) of the strut structure (22) extends transversely to at least a second of the struts (26) of this strut structure (22),wherein the strut structure (22) is formed in two parts, and in the first part of the strut structure (22) between the foil-like electrode element (14) and the metal electrode (12) only the at least one first strut (24) of the strut structure (22) is arranged, which extends from a first frame part of the base body (20) for forming the upper side (28) of the holding device (18) to a second frame part of the base body (20) for forming the underside (30) of the holding device (18) in such a way that a gas component present in the electrolyte can escape as gas bubbles towards the upper side of the battery cell (10), and in the second part of the strut structure (22) on the side (32) of the foil-like electrode element (14) facing away from the metal electrode (12), only the at least one second strut (26) of the strut structure (22) is arranged. [2] Battery cell according to claim 1, characterized bythat the at least one first strut (24) has a depth extension T ≥ 3mm over its entire length. [3] Battery cell according to claim 1 or 2, characterized by that the at least one strut structure (22) has a plurality of first struts (24) and a plurality of second struts (26), particularly preferably two first struts (24) and three second struts (26). [4] Battery cell according to one of the preceding claims, characterized by that the at least one first strut (24) is integrally connected to the frame-like base body (20). [5] Battery cell according to one of the preceding claims, characterized by that the holding device (18) has at least one support frame (56) which can be fastened in / on the base body (20), preferably fastened by clipping, and which supports the second struts (26) of the one strut structure (22) or at least one of the strut structures (22). [6] Battery cell according to one of the preceding claims, characterized bytwo foil-like electrode elements (14) surrounding the metal electrode (12) on both sides to form two air counter electrodes (16) of the metal electrode (12). [7] Battery cell according to one of the preceding claims, characterized by that the holding device has a removable cover (40) on one of its sides, preferably on its top side (28). [8] Battery cell according to one of the preceding claims, characterized by that the holding device (18) has a liquid-impermeable gas outlet (48) on its upper side (28). [9] Battery cell according to one of the preceding claims, characterized by that the holding device (18) has at least one fluid connection (36, 38) for supplying and / or removing electrolyte (34). [10] Holding device for a battery cell (10) having at least one foil-like electrode element (14) and a metal electrode (12), in particular according to one of the preceding claims, wherein the holding device (18) has a frame-like base body (20) and at least one strut structure (22) arranged in the frame-like base body (20) with a plurality of struts (24, 26) extending in the frame plane spanned by the base body (20) for mechanically supporting the foil-like electrode element (14), wherein the metal electrode (12) as well as the at least one electrode element (14) can be enclosed adjacently and spaced apart from one another in the frame-like base body (20), and at least a first of the struts (24) of the strut structure (22) extends transversely to at least a second of the struts (26) of this strut structure (22),wherein the strut structure (22) is formed in two parts and in the first part of the strut structure (22) between the foil-like electrode element (14) and the metal electrode (12) only the at least one first strut (24) of the strut structure (22) is arranged, which extends from a first frame part of the base body (20) for forming the upper side (28) of the holding device (18) to a second frame part of the base body (20) for forming the underside (30) of the holding device (18) in such a way that a gas component present in the electrolyte can escape as gas bubbles in the direction of the upper side of the battery cell (10) and in the second part of the strut structure (22) on the side (32) of the foil-like electrode element (14) facing away from the metal electrode (12) only the at least one second strut (26) of the strut structure (22) can be arranged. [11] Battery module of a metal-air battery, with - an arrangement of battery cells (10), in particular a stack of battery cells (10) and - a clamping device for clamping the arrangement of battery cells (10) in this clamping device, characterized by that the battery cells (10) are designed according to one of claims 1 to 9.

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