ELECTROCHEMICAL CELL AND METHOD FOR PRODUCING AN ELECTROCHEMICAL CELL

Abstract

In order to create an electrochemical cell, comprising a housing, an electrochemical element arranged in an interior of the housing, and at least one cell terminal that comprises a terminal feed-through, which extends through a through-opening of the housing, which electrochemical cell is of simple construction and requires a low production expenditure but still reliably limits the short circuit current that arises in the case of a non-regular operating state, it is proposed that the electrochemical cell comprises an electrically conductive sealing element, which seals the through-opening of the housing and electrically conductively connects the cell terminal to the housing.

Claims

1. An electrochemical cell, comprising a housing, an electrochemical element arranged in an interior of the housing, and at least one cell terminal, which comprises a terminal feed-through that extends through a through-opening of the housing, wherein the electrochemical cell comprises an electrically conductive sealing element, which seals the through-opening of the housing and electrically conductively connects the cell terminal to the housing.

2. The electrochemical cell in accordance with claim 1, wherein the sealing element comprises a plastic material.

3. The electrochemical cell in accordance with claim 1, wherein the sealing element comprises at least one of a polypropylene material, a polybutylene terephthalate material, and an epoxy resin material.

4. The electrochemical cell in accordance with claim 1, wherein the sealing element comprises an electrically conductive additive.

5. The electrochemical cell in accordance with claim 4, wherein the electrically conductive additive comprises at least one of metallic particles, an electrically conductive carbon modification, and an electrically conductive ceramic material.

6. The electrochemical cell in accordance with claim 1, wherein the sealing element comprises a plastic material that is electrically conductive by doping.

7. The electrochemical cell in accordance with claim 6, wherein the sealing element comprises at least one of a doped polyacetylene material, a doped polypyrrole material, a doped polyaniline material, a doped poly(p-phenylene) material, a doped polythiophene material, a doped poly-3,4-ethylenedioxythiophene, and a doped polystyrene sulfonate (PEDOT:PSS).

8. The electrochemical cell in accordance with claim 1, wherein the sealing element is configured as an injection molded part or as a casting compound part.

9. The electrochemical cell in accordance with claim 1, wherein the cell terminal on which the sealing element is arranged is a positive cell terminal of the electrochemical cell.

10. The electrochemical cell in accordance with claim 1, wherein the electrochemical cell comprises a further cell terminal and a snap-over element, which brings the housing of the electrochemical cell into electrically conductive contact with the further cell terminal when a pressure in the interior of the housing of the electrochemical cell exceeds a threshold pressure value.

11. The electrochemical cell in accordance with claim 1, wherein the housing of the electrochemical cell comprises at least one of aluminum and a stainless steel material.

12. The electrochemical cell in accordance with claim 1, wherein the cell terminal comprises a bent sheet metal part.

13. The electrochemical cell in accordance with claim 1, wherein the cell terminal comprises an elastically deformable region.

14. The electrochemical cell in accordance with claim 13, wherein the elastically deformable region comprises at least one bend.

15. The electrochemical cell in accordance with claim 1, wherein the through-opening of the housing is bounded by a collar.

16. A method for producing an electrochemical cell, wherein the electrochemical cell comprises a housing, an electrochemical element arranged in the interior of the housing, and at least one cell terminal that comprises a terminal feed-through, wherein the method comprises the following: arranging the cell terminal relative to the housing in such a way that the terminal feed-through extends through a through-opening of the housing; producing an electrically conductive sealing element, which seals the through-opening and electrically conductively connects the cell terminal to the housing, from a plastic material that at least one of a) comprises an electrically conductive additive and b) is electrically conductive by doping.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] FIG. 1 shows a schematic longitudinal cut through an electrochemical cell of an electrochemical device, the cut plane running through an electrochemical element, a housing, two cell terminals, two connecting conductors, which each electrically conductively connect a cell terminal to the electrochemical element, a sealing element, which seals the through-opening of the housing and electrically conductively connects one of the cell terminals to the housing, an insulating element, which electrically insulates a further cell terminal of the electrochemical cell from the housing, and a snap-over element, which brings the housing of the electrochemical cell into electrically conductive contact with the further cell terminal when a pressure in the interior of the housing exceeds a threshold pressure value, the electrochemical cell being in a normal operating state in which the snap-over element is at a distance from the further cell terminal;

[0067] FIG. 2 shows a schematic longitudinal cut, corresponding to FIG. 1, through the same electrochemical cell in a short circuit state in which the snap-over element electrically conductively connects the housing of the electrochemical cell to the further cell terminal after the pressure in the interior of the housing exceeded a threshold pressure value;

[0068] FIG. 3 shows a schematic depiction of a material of the sealing element, which comprises a plastic material that itself is not electrically conductive and an electrically conductive phase of an electrically conductive additive, the proportion of the electrically conductive additive being set such that the sealing element has neither too high nor too low an electrical conductivity;

[0069] FIG. 4 shows a schematic depiction of a material of the sealing element, which comprises a plastic material that itself is not electrically conductive and an electrically conductive phase of an electrically conductive additive, the proportion of the electrically conductive additive being too low to make the sealing element electrically conductive;

[0070] FIG. 5 shows a schematic depiction of a material of the sealing element, which comprises a plastic material that itself is not electrically conductive and an electrically conductive phase of an electrically conductive additive, the proportion of the electrically conductive additive being so high that the sealing element has too high an electrical conductivity;

[0071] FIG. 6 shows a schematic sectional depiction corresponding to FIG. 1 of a second embodiment of the electrochemical cell in which the through-opening of the housing on which the sealing element is arranged is bounded by a collar;

[0072] FIG. 7 shows a schematic sectional depiction, corresponding to FIG. 1, of a third embodiment of the electrochemical cell in which the cell terminal of the electrochemical cell on which the sealing element is arranged comprises a bent sheet metal part; and

[0073] FIG. 8 comprises a sectional depiction, corresponding to FIG. 1, of a fourth embodiment of the electrochemical cell in which the cell terminal on which the sealing element is arranged has an elastically deformable region that comprises a plurality of bend lines.

[0074] The same or functionally equivalent elements are provided with the same reference numerals in all Figures.

DETAILED DESCRIPTION OF THE INVENTION

[0075] An electrochemical cell, depicted in FIGS. 1 and 2 and denoted as a whole with 100, comprises a housing 102, which may be of one- or two-part configuration, an electrochemical element 104 arranged in the housing 102, which is electrically conductively connected to a terminal feed-through 108 of a first cell terminal 110 by way of a first connecting conductor 106 and is electrically conductively connected to a terminal feed-through 114 of a second cell terminal 116 by way of a second connecting conductor 112, and an electrical insulating element 118, by means of which the terminal feed-through 114 of the second cell terminal 116 is electrically insulated from the housing 102.

[0076] Furthermore, the electrochemical cell 100 comprises an electrically conductive sealing element 120, which seals a through-opening 122 of the housing 102 of the electrochemical cell 100, through which through-opening 122 the terminal feed-through 114 of the first cell terminal 110 extends from the outside space of the housing 102 into its interior 124.

[0077] Furthermore, the sealing element 120 electrically conductively connects the first cell terminal 110 to the housing 102 of the electrochemical cell 100.

[0078] The sealing element 120 comprises, for example, a plastic material and an electrically conductive additive.

[0079] The plastic material may be, in particular, a thermoplastic material, for example a polypropylene material or a polybutylene terephthalate material.

[0080] When using a thermoplastic material, the sealing element is preferably produced in situ on the through-opening 122 of the housing 102 by an injection molding operation.

[0081] Alternatively hereto, provision may be made that the sealing element 120 comprises a thermosetting material, for example an epoxy resin material.

[0082] In this case, the sealing element 120 is preferably produced in situ on the through-opening 122 of the housing 102 of the electrochemical cell 100 by a casting operation.

[0083] The electrically conductive additive 126 contained in the sealing element 120 may comprise, for example, metallic particles, in particular aluminum particles, and/or a carbonaceous material, for example graphite and/or soot.

[0084] The electrical conductivity of the sealing element 120 can be set in a targeted manner by the proportion of the conductive additive 126 in the material of the sealing element 120.

[0085] If the proportion of the conductive additive 126 that is embedded in the plastic matrix 128 of the sealing element 120 in the material of the sealing element 120 is too low, as schematically depicted in FIG. 4, then no continuous electrically conductive percolation paths arise in the sealing element 120, such that the sealing element 120 has no electrical conductivity.

[0086] If the proportion of the conductive additive 126 in the material of the sealing element 120 is too high, as schematically depicted in FIG. 5, then the sealing element 120 has too low an electrical resistance to bring about a current limitation of the short circuit path between the first cell terminal 110 and the second cell terminal 116.

[0087] The proportion of the conductive additive 126 in the material of the sealing element 120 is therefore, as depicted in FIG. 3, selected such that the sealing element 120 forms a desired ohmic contact resistance between the first cell terminal 110 and the housing 102 of the electrochemical cell 100 in the range of preferably about 1.Math.10.sup.1Ω to about 1.Math.10.sup.7Ω.

[0088] The specific electrical conductivity of the material of the sealing element 120 is preferably at least 10.sup.−3 S/m and preferably at most 10.sup.3 S/m.

[0089] Alternatively to the use of a plastic material that itself is not conductive and an electrically conductive additive, the desired electrical conductivity of the sealing element 120 can also be produced by using a plastic material that itself is electrically conductive, in particular a plastic material made electrically conductive by doping.

[0090] In particular, the sealing element 120 may be made, for example, from a doped polyacetylene material, from a doped polypyrrole material, from a doped polyaniline material, from a doped poly(p-phenylene) material, or from a doped polythiophene material.

[0091] When using a plastic material made electrically conductive by doping, the conductivity of the sealing element 120 can be set by the doping level of the plastic material used.

[0092] Furthermore, the electrochemical cell 100 comprises a snap-over element 130, which is arranged opposite the second cell terminal 116 on the housing 102 of the electrochemical cell 100.

[0093] In the normal operating state of the electrochemical cell 100 depicted in FIG. 1, the snap-over element 130 is in a rest state in which the snap-over element 130 projects into the interior 124 of the housing 102.

[0094] When the pressure in the interior 124 of the housing 102 exceeds a threshold pressure value, the snap-over element 130 then transitions from this rest state into the working state depicted in FIG. 2 in which the snap-over element 130 projects into the outside space 132 of the housing 102.

[0095] An increase in the pressure in the interior 124 of the housing 102 beyond the threshold pressure value is, in particular, caused by electrochemical processes and by the development of heat when the electrochemical cell 100 is overcharged.

[0096] In the working state of the snap-over element 130 depicted in FIG. 2, which corresponds to a short circuit state of the electrochemical cell 100, the first cell terminal 110 and the second cell terminal 116 of the electrochemical cell 100 are electrically conductively connected to one another by way of the sealing element 120, the housing cover 102, and the snap-over element 130, such that the electrochemical cell 100 is short circuited.

[0097] Due to the short circuit between the first cell terminal 110 and the second cell terminal 116, the electrochemical cell 100 is discharged in a controlled manner.

[0098] The short circuit reduces the potential difference between the first cell terminal 110 and the second cell terminal 116, which is detectable by means of a battery management system (BMS)—which is not depicted—to which the electrochemical cell 100 is connected.

[0099] The BMS can cancel a charging operation on the electrochemical cell 100 or on all electrochemical cells 100 of a cell module of an electrochemical device upon detection of a short circuit of the electrochemical cell 100.

[0100] Alternatively or in addition hereto, a warning message can be generated by the BMS, for example by means of suitable software, upon detection of a short circuit on the electrochemical cell 100.

[0101] Then, for example, a charging operation on the electrochemical cell 100 can be manually canceled on the basis of such a warning message.

[0102] Because the sealing element 120 has a sufficiently high current limiting resistance in the short circuit path of the electrochemical cell 100, the short circuit current is limited by the housing 102 and the snap-over element 130, such that damage to the snap-over element 130, which would interrupt the short circuit current path, is excluded.

[0103] This prevents the electrochemical cell 100 from being further overcharged and brought into a critical state.

[0104] In a variant (not depicted) of the electrochemical cell 100, a current flow interrupting device is provided, which, for example, comprises a fuse and interrupts the charging current that is applied to the electrochemical cell 100, such that an overcharging of the electrochemical cell 100 is prevented in this case, too.

[0105] Furthermore, the safety of the electrochemical cell 100 is increased by the current-limiting resistance of the sealing element 120, since the current flowing is limited in the case of unintentional contact of the housing 102 of the electrochemical cell 100 and thus the risk of an electrical shock is reduced.

[0106] The first cell terminal 110 on which the sealing element 120 is arranged may be a negative cell terminal or a positive cell terminal of the electrochemical cell 100.

[0107] The second cell terminal 116, adjacent to which the snap-over element 130 is arranged, has the respective opposite polarity to the first cell terminal 110, and is thus configured as a positive cell terminal or as a negative cell terminal.

[0108] If the first cell terminal 110 is a positive cell terminal and the second cell terminal 116 is a negative cell terminal, the housing 102 is preferably made primarily of aluminum.

[0109] If the first cell terminal 110 is a negative cell terminal and the second cell terminal 116 is a positive cell terminal, the housing 102 is preferably made of a stainless steel material.

[0110] A second embodiment depicted in FIG. 6 of an electrochemical cell 100 differs from the first embodiment depicted in FIGS. 1 to 5 in that the through-opening 122 of the housing 102 through which the terminal feed-through 114 of the first cell terminal 110 on which the sealing element 120 is arranged extends is bounded by a collar 134.

[0111] The collar 134 may be formed on the housing 102, for example, by a deep drawing operation.

[0112] The collar 134 on the through-opening 122 of the housing 102 may, in principle, project into the outside space 132 of the housing 102 or into the interior 124 of the housing 102.

[0113] The collar 134 preferably projects into the interior 124 of the housing 102.

[0114] The size of the sealing face between the sealing element 120 and the housing 102 of the electrochemical cell 100 is increased by the collar 134, which improves the tightness of the seal created by the sealing element 120.

[0115] In addition, the composite adhesion between the sealing element 120 and the housing 102 is improved by the presence of the collar 134, in particular by the plastic material of the sealing element 120 shrinking onto the collar 134.

[0116] In all other respects, the second embodiment of an electrochemical cell 100 depicted in FIG. 6 corresponds with respect to structure, function, and production method with the first embodiment depicted in FIGS. 1 to 5, to the preceding description of which reference is made in this regard.

[0117] In the embodiment depicted in FIGS. 1 to 6 of an electrochemical cell 100, the first cell terminal 110 on which the sealing element 120 is arranged is of substantially T-shaped configuration in cross section, the base of the “T” forming the terminal feed-through 114, which extends through the through-opening 122 of the housing 102 of the electrochemical cell 100.

[0118] A third embodiment depicted in FIG. 7 of an electrochemical cell 100 differs from the first embodiment depicted in FIGS. 1 to 5 in that the first cell terminal 110 on which the sealing element 120 is arranged comprises a component 136 that has a substantially S-shaped or Z-shaped longitudinal section.

[0119] The component 136 may be configured, in particular, as a bent sheet metal part 138.

[0120] The component 136 can be separated out, for example punched out or cut out—e.g. by means of a laser—from a metal sheet made of a suitable starting material and then be bent into the desired form.

[0121] The component 136 is subsequently adhesively bonded to the housing 102 of the electrochemical cell 100 by means of the material of which the sealing element 120 is made.

[0122] The material from which the component 136 is separated out may have a material transition, in particular between a first region that is made, e.g., primarily of aluminum, and a second region that is made, e.g., primarily of copper.

[0123] These two regions of the starting material for the component 136 may be connected to one another, e.g., by overlap roll cladding.

[0124] In this case, the component 136 is separated out, in particular punched out or cut out—for example by means of a laser—from an overlap roll cladded starting sheet metal material and is subsequently bent into the desired form, for example an S-shape or a Z-shape.

[0125] Due to this manner of production, the number of components required for the first cell terminal 110 and the expenditure for the production of the first cell terminal 110 can be reduced.

[0126] In all other respects, the third embodiment of an electrochemical cell 100 depicted in FIG. 7 corresponds with respect to structure, function, and production method with the first embodiment depicted in FIGS. 1 to 5, to the preceding description of which reference is made in this regard.

[0127] A fourth embodiment depicted in FIG. 8 of an electrochemical cell 100 differs from the third embodiment depicted in FIG. 7 in that the first cell terminal 110 on which the sealing element 120 is arranged comprises an elastically deformable region 140.

[0128] Forces acting on the sealing element 120 and/or on the first cell terminal 110 that are generated, for example, by a movement of the electrochemical element 104 upon an impact load can be absorbed by this elastically deformable region 140 without the sealing function of the sealing element 120 being impaired.

[0129] Provision is preferably made that the elasticity of the elastically deformable region 140 is based on a dimensional elasticity that is caused by at least one additional bend of the component 136.

[0130] In the embodiment that is graphically depicted in FIG. 8, the elastically deformable region 140 comprises, as an example, four bend lines 142 at which the component 136 configured as a sheet metal part 138 is bent by an angle of about 90°.

[0131] Together the bends at the bend lines 142 produce a wave shape of the elastically deformable region 140.

[0132] In all other respects, the fourth embodiment of an electrochemical cell 100 depicted in FIG. 8 corresponds with respect to structure, function, and production method with the third embodiment depicted in FIG. 7, to the preceding description of which reference is made in this regard.

[0133] In principle, an electrochemical cell 100 may have and combine any combinations of the features of the embodiments of electrochemical cells 100 described above and depicted in FIGS. 1 to 8.