Electrochemical single cell

Abstract

The invention relates to an electrochemical single cell (1) comprising a cell housing (2) in which an electrode foil arrangement (3) is arranged, wherein electrode foils of one electrical polarity are electrically connected to a current collector (5) and electrode foils of a further electrical polarity are electrically connected to a further current collector (6), and the respective current collector (5, 6) is electrically connected to a respective current terminal (P1, P2).According to the invention, at least one further current terminal (P2), which is arranged on a cell cover (4) in an electrically insulated manner relative to a current terminal (P1), is electrically connected to the further current collector (6) by means of at least one metal strip (8) which has a deformation for compressing the length, the at least one deformed metal strip (8) is materially fastened to the further current collector (6) and the further current terminal (P2), wherein when an internal pressure threshold value in the cell housing (2) is exceeded, a bursting pressure acts on the further current terminal (P2) to detach the further current terminal (P2) from the cell cover (4), and the at least one metal strip (8) is designed to position the further current terminal (P2) at a predetermined distance from the cell cover (4) by means of its longitudinal expansion in order to release a venting opening (E).

Description

The invention relates to an electrochemical single cell for an electrical energy store, having a cell housing in which an electrode foil arrangement is arranged, wherein electrode foils of one electrical polarity are electrically connected to a current collector and electrode foils of a further electrical polarity are electrically connected to a further current collector, and the current collectors are electrically connected to a respective current terminal.From the prior art, round cells and prismatic individual cells are known as electrochemical individual cells for an electrical energy store.The invention is based on the object of specifying an electrochemical individual cell for an electrical energy store.The object is achieved according to the invention by an electrochemical single cell which has the features specified in claim 1.Advantageous embodiments of the invention are the subject matter of the dependent claims.A single electrochemical cell for an electrical energy store has a cell housing in which an electrode foil arrangement is arranged, wherein electrode foils of one electrical polarity are electrically connected to a current collector and electrode foils of another electrical polarity are electrically connected to another current collector, and the current collectors are electrically connected to a current terminal in each case. According to the invention, it is provided thatat least one further current terminal, which is arranged on a cell cover of the cell housing in an electrically insulated manner with respect to a current terminal, is electrically connected to the further current collector by means of at least one metal strip having a deformation for upsetting the length,the at least one formed metal strip is fastened to the further current collector and the further current terminal (P 2) in a materially bonded manner,a burst pressure acts on the further current terminal to release the further current terminal from the cell cover when a predetermined internal pressure threshold value is exceeded in the cell housing, andthe at least one metal strip is designed, after detachment of the further current terminal by its longitudinal extent, to position the further current terminal at a distance from the cell lid predetermined by a length of the at least one metal strip in order to open a degassing opening.An individual cell formed in this way does not require a rupture membrane, since the degassing opening is present, which is closed in the normal state of the individual cell by means of the further power terminal, which is fixed by means of the at least one formed metal strip, is released when the predetermined internal pressure threshold value is exceeded. Thus, no additional installation space is required for forming a rupture opening, i.e. degassing opening, closed by means of a rupture membrane. By means of the degassing opening arranged in this way, it is possible to prevent the electrode film arrangement from escaping from the cell housing to the greatest possible extent when the degassing opening is released, and therefore it is possible to optimize design of degassing paths of an individual cell and assembly concepts. In particular, such a configuration is suitable both for individual cells with a circular cylindrical cell housing and for individual cells with a prismatic cell housing.The electrical current terminals can be maximized in terms of area, as a result of which contacting with respect to an electrical interconnection of a plurality of such individual cells for forming an electrical energy store is simplified. Based on the current terminals maximized in terms of area, longer and / or wider welded seams and / or a different type of connection of the electrical contacting are possible, so that an electrical current flow can be increased.The internal pressure threshold value can be predefined by means of an electrically insulating plastic ring and / or another type of connection between the further current terminal and the cell cover.In addition, it is possible for both electrical current terminals of the individual cell to be arranged, for example, on one and the same end face of the cell housing, such that a thermally conductive potting compound filled into a housing of the electrical energy store, in particular a lateral surface of the cell housing, can completely enclose.Exemplary embodiments of the invention are explained in more detail below with reference to drawings.The following are shown: FIG. 1 schematically shows a sectional illustration of an electrochemical single cell in a normal operating state, and FIG. 2 schematically shows a sectional illustration of a thermally continuous electrochemical single cell.Corresponding parts are provided with the same reference numerals in all figures.FIG. 1 shows, by way of example and in a greatly simplified manner, a sectional illustration of an electrochemical individual cell 1 in a normal operating state, whereas FIG. 2 shows, by way of example and in a greatly simplified manner, a sectional illustration of a thermally continuous electrochemical individual cell 1. The individual cell 1 is designed as a round cell and has a circular cylindrical cell housing 2.The cell housing 2 usually has a degassing opening E which is closed with a rupture membrane in the normal operating state of an individual cell 1. If the individual cell 1 passes through thermally, for example because of an internal electrical short circuit, an internal pressure in the cell housing 2 increases. If the internal pressure exceeds a predetermined internal pressure threshold value, the rupture membrane burst, so that the degassing opening E of the cell housing 2 is released, gas can escape from the cell housing 2 and thus the internal pressure in the cell housing 2 can decrease.The installation of such a rupture membrane during the production of the individual cell 1 is comparatively complicated, wherein the degassing opening E closed by means of the rupture membrane restricts the installation space requirement for the arrangement of electrical power terminals P 1, P 2 of the individual cell 1 and the dimensions of the power terminals P 1, P 2. As a result, further electrical contacting with other components, in particular further individual cells 1, can be restricted. For this reason, the current terminals P 1, P 2 of the individual cell 1 are often arranged on opposite end faces of the cell housing 2, as a result of which an installation position of the individual cell 1 is already predefined and therefore a structure of the electrical energy store is predefined and cannot be changed.In order to dispense with a rupture membrane and also to arrange the current terminals P 1, P 2 of the individual cell 1 on an end face of the cell housing 2, wherein the current terminals P 1, P 2 are enlarged in terms of area, the individual cell 1 is designed as described below.The individual cell 1 has a circular cylindrical cell housing 2, in which an electrode film arrangement 3, in particular an electrode film roll, a so-called jellyroll, is arranged. The cell housing 2 is closed in a medium-tight manner by a cell cover 4.The electrode foil assembly 3 comprises a plurality of electrode foils, electrode foils of one electrical polarity being electrically connected to a current collector 5 and electrode foils of another electrical polarity being electrically connected to another current collector 6.The current collector 5 is electrically conductively connected to an electrical current terminal P 1 formed by means of the cell housing 2 and / or the cell lid 4, and the further current collector 6 is electrically conductively connected to the further current terminal P 2, wherein the two current terminals P 1, P 2 are arranged electrically insulated from one another by means of an electrical insulation element 7, in particular in the form of a plastic insulation ring.According to the exemplary embodiment shown in FIGS. 1 and 2, the further current collector 6 is electrically connected to the further current terminal P 2 by means of four circumferentially arranged metal strips 8, wherein two are arranged opposite one another in each case.In particular, the metal strips 8 are welded to the further current collector 6 and the further current terminal P 2, wherein the metal strips 8 are deformed, for example compressed in length, in a normal operating state of the individual cell 1. The forming in this case results in particular from a bending and / or folding, wherein the metal strips 8 are bent in FIG. 1.The further current terminal P 2 is fixed in its position in particular exclusively by means of the insulation element 7 on the cell cover 4 of the cell housing 2.If the individual cell 1 passes through thermally, for example because of an internal electrical short circuit, and an internal pressure in the cell housing 2 exceeds an internal pressure threshold value, which is predetermined in particular by means of the insulation element 7, the electrical insulation element 7 yields as a result of an acting burst pressure, in particular of more than 5 bar, and tears, for example. As a result, the further current terminal P 2 of the individual cell 1 is only still connected to the metal strips 8, which expand in their length due to the lack of fixing of the further current terminal P 2 and thus the further current terminal P 2 is positioned away from the cell cover 4 due to a prevailing internal pressure. Thus, a degassing opening E of the cell housing 2 formed below the further power terminal P 2 is released and a gas can escape from the cell housing 2. In particular, the gas can escape through a clearance created between further current terminal P 2 and cell cover 4, wherein it is substantially prevented that the electrode foil arrangement 3 can escape through the degassing opening E to the outside of the cell housing 2.In particular, the metal strips 8 expand in their length without contact with current-carrying components of the individual cell 1 when the fixing of the further current terminal P 2 is canceled, whereby a risk of short circuit can be reduced. In this case, a length of the respective metal strip 8 specifies a distance of the further current terminal P 2 from the cell cover 4 and thus a size of the free space.List of reference characters1 Single cell 2 Cell housing 3 Electrode foil arrangement 4 Cell lid 5 Current collector 6 Further current collector 7 Insulation element 8 Metal strip E Degassing opening P 1 Current terminal P 2 Further current terminal

Claims

Electrochemical individual cell (1) for an electrical energy store, having a cell housing (2) in which an electrode foil arrangement (3) is arranged, wherein electrode foils of an electrical polarity are electrically connected to a current collector (5) and electrode foils of a further electrical polarity are electrically connected to a further current collector (6), and the current collectors (5, 6) are each electrically connected to a current terminal (P1, P2), characterized in that - at least one further current terminal (P2) arranged on a cell cover (4) of the cell housing (2) in an electrically insulated manner with respect to a current terminal (P1) is electrically connected to the further current collector (6) by means of at least one metal strip (8) having a deformation for upsetting the length, - the at least one deformed metal strip (8) is fastened to the further current collector (6) and the further current terminal (P2) in a materially bonded manner, - when a predetermined internal pressure threshold value in the cell housing (2) is exceeded, a burst pressure acts on the further current terminal (P2) for detaching the further current terminal (P2) from the cell cover (4), and - the at least one metal strip (8) is designed, after detaching the further current terminal (P2) by its longitudinal extension, to position the further current terminal (P2) for releasing a degassing opening (E) at a distance from the cell cover (4) predetermined by a length of the at least one metal strip (8).Electrochemical single cell (1) according to Claim 1, characterized in that the at least one metal strip (8) is formed by bending and / or folding in the normal operating state.Electrochemical single cell (1) according to claim 1 or 2, characterised in that the at least one metal strip (8) is welded to the further current collector (6) and the further current terminal (P2).Electrochemical individual cell (1) according to one of the preceding claims, characterized in that the cell housing (2) is of circular cylindrical or prismatic design.

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