Electrochemical single cell and battery

Abstract

The invention relates to an electrochemical single cell (10) for a battery, in particular for a high-voltage traction battery of an electrically powered vehicle, comprising at least a cell housing (12) with a first terminal (22) and a second terminal (24), and an electrode pack (30) arranged in an interior (14) of the cell housing (12), which is electrically connected to the first terminal (22) and the second terminal (24) by means of electrical connecting lines (26). At least one of the two terminals (22, 24) is arranged without welding in a housing opening (50) and seals the housing opening (50) tightly during intended operation. The at least one of the two terminals (22, 24) is designed to selectively release the housing opening (50) in the event of a pressure increase in the interior (50) of the cell housing (12). The invention further relates to a battery (100), in particular a high-voltage traction battery of an electrically powered vehicle.

Description

[0001] The invention relates to an electrochemical single cell for a battery, in particular for a high-voltage traction battery of an electrically driven vehicle, and to a battery, in particular a high-voltage traction battery of an electrically driven vehicle.

[0002] Traction batteries for electric vehicles typically contain multiple battery cells, often designed as so-called prismatic hard-case cells. These are electrically interconnected via terminal connections, often designed as contact rivets.

[0003] The battery cell has a prismatic cell housing, inside which an electrode stack and liquid electrolyte are arranged. The electrodes are electrically connected to the terminal connections at their conductors via connecting lines. The electrode stack is usually surrounded by an insulating film. The individual cell, for example, is located on the housing base of a traction battery. The two terminal connections are usually firmly riveted to the cell housing cover. A so-called venting membrane, for example in the form of a bursting disc, is usually arranged between the two contact rivets in the housing cover. In the event of excess pressure in the cell, the membrane bursts and releases the resulting gas into the environment, a process also known as venting.

[0004] DE 10 2015 010 342 A1 describes a battery cell for a battery assembly. The battery cell comprises a cell housing with a pressure equalization opening, a first battery terminal, a second battery terminal, a galvanic element arranged in an interior of the cell housing, which is connected between the first battery terminal and the second battery terminal, a contact element electrically coupled to the second battery terminal, and a deformable, electrically conductive membrane with which the pressure equalization opening is closed.The membrane is electrically coupled to the first battery terminal and is designed to be deformed at the pressure equalization opening toward an exterior of the cell housing upon a pressure increase in the interior of the cell housing, thereby establishing permanent electrical contact with the contact element when a predeterminable differential pressure between the interior and the exterior is exceeded. The battery cell is further designed to be electrically conductive after the electrical connection has been established.

[0005] Contact to permanently discharge the galvanic element via the electrical contact.

[0006] DE 10 2020 110 700 A1 describes a battery for a motor vehicle, comprising a plurality of prismatic battery cells arranged in a battery housing of the battery, each having two terminals for electrically contacting the battery cell and a cell housing with an outlet opening that is fluidically connected to an interior of the cell housing via a pressure relief valve and through which gas can be discharged from the interior. Each of the battery cells is overlapped by a separate formed sheet metal part, which is arranged at a distance from the respective outlet opening and, together with the respective cell housing, encloses a flow chamber into which the outlet opening opens.

[0007] An object of the invention is to provide an improved electrochemical single cell for a battery, in particular for a high-voltage traction battery of an electrically powered vehicle.

[0008] A further object is to create an improved battery, in particular a high-voltage traction battery for an electrically powered vehicle.

[0009] The above-mentioned objects are solved by the features of the independent claims.

[0010] Advantageous embodiments and advantages of the invention emerge from the further claims, the description and the drawing.

[0011] According to one aspect of the invention, an electrochemical single cell for a battery, in particular for a high-voltage traction battery of an electrically powered vehicle, is proposed, at least comprising a cell housing with a first terminal connection and a second terminal connection, and an electrode package arranged in an interior of the cell housing, which electrode package is electrically connected to the first terminal connection and the second terminal connection by means of electrical connecting lines. At least one of the two terminal connections is arranged unwelded in a housing opening and tightly closes the housing opening during normal operation. At least one of the two terminal connections is designed to specifically open the housing opening when the pressure in the interior of the cell housing increases.

[0012] In the proposed single cell, at least one of the two terminal connections takes on the function of a rupture disc. For this purpose, the terminal connection is connected to the cell housing without being welded. Unwelded means that the terminal connection is not welded or soldered to the cell housing. Instead, the terminal connection can be connected to the cell housing by force fit or by adhesion, in particular by adhesion through gluing, so that the connection between the terminal connection and the cell housing can be released by excess pressure in the cell housing. At a defined excess pressure, the terminal connection can specifically open the housing opening, which the terminal connection closes during normal operation, and the gas inside the single cell can flow out into the environment around the single cell.

[0013] If excessive pressure occurs, the terminal connection opens, thus releasing a large pressure equalization cross-section. The resulting gas escape ensures a rapid drop in the cell's internal pressure to ambient pressure. There is no risk of internal pressure-induced deformation of the cell casing. Likewise, the electrolyte level drops due to the discharge of electrolyte particles.

[0014] The individual cell can advantageously have large contact cross-sections, as the two terminal connections can occupy a large portion of the entire cover surface of the cell housing. This prevents the terminal connections from heating up at high currents. It also reduces the introduction of ohmic heat into the cell interior. Thermal overload of the individual cell can be advantageously avoided.

[0015] The venting cross-section is significantly increased due to the comparatively large housing openings. This allows gases to be quickly released from the interior of the individual cell. In the case of extremely exothermic reactions within the cell, two venting cross-sections can be released by opening the housing openings of the two terminal connections, allowing larger amounts of gas to be released in a short time.

[0016] The proposed single cell can be manufactured cost-effectively because it eliminates the need for a separate venting element, which is otherwise required for safety reasons but does not contribute to fulfilling the basic function of the single cell, namely storing electrical energy.

[0017] According to an advantageous embodiment of the electrochemical single cell, at least one of the two terminal connections can be electrically connected to the electrode stack by means of the electrical connecting line when the housing opening is exposed. The continued electrical contact between the electrode stack and the terminal connection, due to the long connecting line, advantageously allows for subsequent residual electrical discharge of the single cell.

[0018] According to an advantageous embodiment of the single electrochemical cell, at least one of the two terminal connections can be connected to the cell housing by force-locking and / or by adhesion. For example, the terminal connection can be pressed into the housing opening. Alternatively, it is also possible for the terminal connection to tightly seal the cell housing by adhesion, for example, by bonding. The bond can tear open under sufficient internal pressure in the interior, specifically exposing the housing opening.

[0019] According to an advantageous embodiment of the single electrochemical cell, the pressure at which at least one of the two terminal connections specifically opens the housing opening can be set or adjustable at least by a type of connection between at least one of the two terminal connections and the cell housing. Thus, the pressure at which the single cell opens can be predetermined by the selected strength of the mechanical connection, for example, by the choice of adhesive or the type of frictional connection between the terminal connection and the housing opening.

[0020] According to an advantageous embodiment of the single electrochemical cell, at least one lateral extension of at least one of the two terminal connections can be at least 25%, preferably at least 30%, particularly preferably at least 40%, of a corresponding lateral extension of the cell housing. This ensures particularly favorable opening of the cell housing and thus sufficient venting of the gases contained in the interior.

[0021] According to an advantageous embodiment of the single electrochemical cell, the cross-sectional area of ​​the housing opening can be at least 25%, preferably at least 30%, and particularly preferably at least 40%, of the area of ​​a cover of the cell housing. This ensures particularly favorable opening of the cell housing and thus sufficient venting of the gases contained in the interior.

[0022] According to an advantageous embodiment of the electrochemical single cell, the length of the electrical connecting line can correspond to at least one lateral extension of the terminal connection. This ensures that, despite the terminal connection being removed from its normal position in the housing opening, the electrical contact between the electrode stack and the terminal connection is maintained, allowing the single cell to be electrically discharged despite the cell housing being open.

[0023] According to an advantageous embodiment of the single electrochemical cell, the first and second terminal connections can be arranged in a housing opening and tightly seal the housing opening during normal operation. The first and second terminal connections can be designed to specifically open the housing opening when the pressure inside the cell housing increases. In the case of extreme exothermic reactions inside the cell, two venting cross-sections can be opened by opening the housing openings of the two terminal connections, allowing larger amounts of gas to be released in a short time via the larger venting cross-section in the cell housing.

[0024] According to an advantageous embodiment of the electrochemical single cell, the first and second terminal connections can be electrically connected to the electrode stack by means of the electrical connecting lines when the housing opening is exposed. The continued electrical contact between the electrode stack and the terminal connection, due to the long connecting line, advantageously allows for subsequent residual electrical discharge of the single cell.

[0025] According to a further aspect of the invention, a battery, in particular a high-voltage traction battery of an electrically driven vehicle, is proposed, comprising a plurality of individual electrochemical cells connected in series and / or in parallel.

[0026] The proposed battery can incorporate the electrochemical individual cells described above. This ensures sufficient battery safety in the event of a gas release due to overpressure in at least one individual cell. Due to the low manufacturing costs of the individual cell by eliminating the need for a rupture disc or venting membrane, cost savings can be demonstrated for the entire battery.

[0027] Further advantages will become apparent from the following description of the drawings. The drawings illustrate an exemplary embodiment of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0028] Showing: Fig. 1 shows a schematic structure of an electrochemical single cell for a battery, in particular for a high-voltage traction battery of an electrically powered vehicle, according to an embodiment of the invention; Fig. 2 the electrochemical single cell according to Fig. 1 with an open housing opening; and Fig. 3 shows a schematic structure of a battery, in particular a high-voltage traction battery of an electrically driven vehicle, according to an embodiment of the invention.

[0029] In the figures, identical or similar components are numbered with the same reference numerals. The figures show only examples and are not to be understood as limiting.

[0030] Fig. 1 shows a schematic structure of an electrochemical single cell 10 for a battery 100, in particular for a high-voltage traction battery of an electrically powered vehicle, according to an embodiment of the invention.

[0031] The single cell 10 comprises a cell housing 12 with a first pole connection 22 and a second pole connection 24, as well as an electrode package 30 arranged in an interior space 14 of the cell housing 12, which is electrically connected to the first pole connection 22 and the second pole connection 24 by means of electrical connecting lines 26.

[0032] The individual cell 10 has the prismatic cell housing 12, which is formed from a wall 18, a base 20, and a cover 16, and in whose interior 14 the electrode pack 30 and liquid electrolyte 28 are arranged. The electrodes 32, 34, which are shown slightly offset for clarity, are electrically connected to the terminal connections 22, 24 at their conductors 36, 38 by means of connecting lines 26. The electrode pack 30 is surrounded by an insulating film 40. The individual cell stands on the base of a battery housing 102 of the traction battery 100. The two terminal connections 22, 24 are arranged unwelded in housing openings 50 and are glued, for example, to the cover 16 of the cell housing 12. The two terminal connections 22, 24 thus tightly seal the housing opening 50 during normal operation.

[0033] At least one of the two terminal connections 22, 24 is designed to specifically open the housing opening 50 in the event of a pressure increase in the interior 50 of the cell housing 12. In the event of excess pressure in the individual cell 10, the adhesive bond securing the terminal connection 22, 24 in the housing opening 50 breaks, the terminal connection 22, 24 opens the housing opening 50, and releases the resulting gas into the environment.

[0034] Fig. 2 shows the single cell 10 after Fig. 1 with an open housing opening 50. The corresponding terminal connection 24 protrudes diagonally from the cover 16 of the cell housing 12 and has exposed the housing opening 50. Gases and liquid and / or gaseous electrolyte 28 flow out of the interior space 14. The liquid level of the electrolyte 28 in the cell housing 12 has consequently decreased.

[0035] In the state in which the housing opening 50 is exposed, the terminal connection 24 is still electrically connected to the electrode pack 30 via the electrical connecting line 26. As a result, the individual cell 10 can be electrically discharged even in this state.

[0036] A pressure at which the at least one of the two pole terminals 22, 24 specifically releases the housing opening 50 can advantageously be adjusted by the type of connection of the at least one of the two pole terminals 22, 24 to the cell housing 12, for example by the choice of the adhesive.

[0037] In order for the at least one of the two terminal connections 22, 24 to release the housing opening 50 sufficiently quickly by tearing open the connection between the terminal connection 22, 24 and the housing opening 50, for example, at least one lateral extension 44 of the at least one of the two terminal connections 22, 24 can be at least 25%, preferably at least 30%, particularly preferably at least 40%, of a corresponding lateral extension 46 of the cell housing 12, as in Fig. 1 recognizable.

[0038] In order to be able to blow off the gas located in the interior 14 sufficiently quickly in the event of overpressure, a cross-sectional area of ​​the housing opening 50 can be, for example, at least 25%, preferably at least 30%, particularly preferably at least 40%, of an area of ​​a cover 16 of the cell housing 12.

[0039] In order to maintain the electrical connection between the electrode package 16 and the pole terminals 22, 24 even in the event of venting, a length of the electrical connecting line 26 can correspond to at least one lateral extension 44 of the pole terminal 22, 24, as shown in Fig. 1 recognizable, correspond.

[0040] In the event of extreme exothermic reactions in the cell interior 14, two venting cross-sections can be exposed by opening the housing openings 50 of the two terminal connections 22, 24, in order to release larger quantities of gas in a short time via the larger venting cross-section in the cell housing 12. Thus, both terminal connections 22, 24 can advantageously be designed to specifically expose the housing opening 50 in the event of a pressure increase in the interior 50 of the cell housing 12. Advantageously, both terminal connections 22, 24 can remain electrically connected to the electrode stack 30 by means of the electrical connecting lines 26 in the state in which the housing opening 50 is exposed, in order to enable the individual cell 10 to be electrically discharged even in this state.

[0041] In Fig. 3 shows a schematic structure of a battery 100, in particular a high-voltage traction battery of an electrically powered vehicle, according to an embodiment of the invention.

[0042] The battery 100 comprises a plurality of individual electrochemical cells 10 connected in series. The individual cells 10, which are stacked in a battery housing 102, are electrically connected by cell connectors 104. The high-voltage terminals 106, 108 extend out of the battery housing 102. List of reference symbols 10 battery cells 12 cell housings 14 Interior 16 lids 18 wall 20 floor 22-pin connection 24-pin connection 26 electrical connection 28 Electrolyte 30 electrode pack 32 positive electrode 34 negative electrode 36 arresters 38 arresters 40 insulating foil 44 lateral extension pole connection 46 lateral extension of cell housing 50 Housing opening 100 batteries 102 Battery housing 104 cell connectors 106 High-voltage connection 108 High-voltage connection QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2015 010 342 A1

[0004] DE 10 2020 110 700 A1

[0006]

Claims

[1] Electrochemical single cell (10) for a battery, in particular for a high-voltage traction battery of an electrically driven vehicle, comprising at least - a cell housing (12) with a first terminal connection (22) and a second terminal connection (24), - an electrode package (30) arranged in an interior space (14) of the cell housing (12), which is electrically connected to the first pole connection (22) and the second pole connection (24) by means of electrical connecting lines (26), wherein at least one of the two pole connections (22, 24) is arranged unwelded in a housing opening (50) and tightly closes the housing opening (50) during normal operation, wherein the at least one of the two pole connections (22, 24) is designed to specifically open the housing opening (50) when the pressure in the interior space (50) of the cell housing (12) increases. [2] Electrochemical single cell according to claim 1, wherein the at least one of the two pole terminals (22, 24) is electrically connected to the electrode package (30) by means of the electrical connecting line (26) in a state in which the housing opening (50) is released. [3] Electrochemical single cell according to claim 1 or 2, wherein at least one of the two pole terminals (22, 24) is connected to the cell housing (12) by force fit and / or by adhesion. [4] Electrochemical single cell according to claim 3, wherein a pressure at which the at least one of the two pole terminals (22, 24) specifically releases the housing opening (50) is set or adjustable at least by a type of connection of the at least one of the two pole terminals (22, 24) to the cell housing (12). [5] Electrochemical single cell according to one of the preceding claims, wherein at least one lateral extension (44) of at least one of the two pole terminals (22, 24) is at least 25%, preferably at least 30%, particularly preferably at least 40%, of a corresponding lateral extension (46) of the cell housing (12). [6] Electrochemical single cell according to one of the preceding claims, wherein a cross-sectional area of ​​the housing opening (50) is at least 25%, preferably at least 30%, particularly preferably at least 40%, of an area of ​​a cover (16) of the cell housing (12). [7] Electrochemical single cell according to one of the preceding claims, wherein a length of the electrical connecting line (26) corresponds to at least one lateral extension (44) of the pole connection (22, 24). [8] Electrochemical single cell according to one of the preceding claims, wherein the first and the second pole connection (22, 24) are arranged in a housing opening (50) and tightly close the housing opening (50) during normal operation, wherein the first and the second pole connection (22, 24) are designed to specifically release the housing opening (50) in the event of a pressure increase in the interior (50) of the cell housing (12). [9] Electrochemical single cell according to claim 8, wherein the first and the second pole terminal (22, 24) are electrically connected to the electrode package (30) by means of the electrical connecting lines (26) in the state in which the housing opening (50) is released. [10] Battery (100), in particular a high-voltage traction battery of an electrically driven vehicle with a plurality of electrochemical individual cells (10) connected in series and / or in parallel according to one of the preceding claims.

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