Battery Cell Having an Electrical Fuse

Abstract

A battery cell has an electrical fuse. The electric fuse is a fusible link which is arranged on a terminal on an outside of a housing of the battery cell. The fusible link is covered by a polymer.

Claims

1-10. (canceled)

11. A battery cell, comprising: an electrical fuse; a terminal on an outer surface of a housing of the battery cell, wherein the electrical fuse is arranged on the terminal, and the electrical fuse is covered by a polymer.

12. The battery cell according to claim 11, wherein the terminal is a positive terminal.

13. The battery cell according to claim 11, wherein the polymer comprises at least one filler that improves heat removal.

14. The battery cell according to claim 13, wherein the filler comprises Al(OH).sub.3 or Al.sub.2O.sub.3.

15. The battery cell according to claim 11, wherein the polymer contains at least one filler that is an oxidant.

16. The battery cell according to claim 15, wherein the filler is ammonium perchlorate.

17. The battery cell according to claim 11, wherein the terminal is electrically insulated from the housing.

18. The battery cell according to claim 11, further comprising: a seal comprising an electrically conductive plastic, the seal being arranged between the terminal and the housing.

19. A lithium-ion battery, comprising: a plurality of battery cells, each battery cell comprising: an electrical fuse; a terminal on an outer surface of a housing of the battery cell, wherein the electrical fuse is arranged on the terminal, and the electrical fuse is covered by a polymer.

20. A motor vehicle comprising a lithium-ion battery according to claim 19.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 is a schematic perspective representation of a housing of the battery cell according to an embodiment;

[0022] FIG. 2A is a schematic detail view of the region of the positive terminal in an exploded representation; and

[0023] FIG. 2B is a schematic detail view of the region of the positive terminal of the battery cell in cross section.

[0024] Identical or identically acting constituents are each provided with identical reference numerals in the figures. The constituents shown and the size ratios of the constituents relative to one another are not to scale.

DETAILED DESCRIPTION OF THE DRAWINGS

[0025] The battery cell 10 shown in schematic form in FIG. 1 is, in the exemplary embodiment shown here, a prismatic battery cell 10. The battery cell 10 comprises a housing 14 which forms a mechanically solid shell for the cell layers of the battery cell 10 arranged therein. In the battery cell 10, the cell layers may be in the form of cell stacks or wound cells for example. In the exemplary embodiment, the housing 14 has a rectangular footprint and is substantially cuboidal. The housing 14 may be formed from a metal or a metal alloy, preferably from aluminum. It is possible for the housing 14 to comprise an electrically insulating coating at least in regions. The battery cell 10 comprises a positive terminal 11 and a negative terminal 12, wherein the terminals 11, 12 are arranged on a lid 6 of the housing 14 for example. The terminals 11, 12 are provided for electrical contracting of the poles of the cell stack or wound cell of the battery cell 10. FIG. 1 further shows a cover 13 arranged on the lid 6 of the housing, which cover 13 is arranged for example in the region between the electrical terminals 11, 12. An overpressure safety apparatus such as for example a rupture membrane may be arranged under the cover 13.

[0026] FIGS. 2A and 2B show details in the region of the positive terminal 11 in an exploded representation and in a cross section. The positive terminal 11 comprises an electrical connection plate 4 which is electrically connected to a current collector 9 of the positive pole (cathode) of the battery cell by a rivet 7 and a fuse 2. The mechanical connections may be produced for example by laser welding. An electrically insulating plate 5 is arranged between the electrical connection plate 4 and the lid 6 of the housing 14. An annular insulator 3, which prevents direct contact between the current-conducting rivet 7 and the connection plate 4, is arranged in a recess of the connection plate 4. The current flow from the current collector 9 to the connection plate 4 is effected via the rivet 7 and the fuse 2 arranged thereabove. The fuse 2 preferably comprises or consists of aluminum.

[0027] The fuse 2 has a safety function in the battery cell 10. When the fuse melts, for example due to excessive currents in the case of a shorting of the battery cell 10, the electrical connection between the current collector 9 and the connection plate 4 of the positive terminal 11 is interrupted.

[0028] In the battery cell 10, the fuse 2 is arranged on the positive terminal 11 outside the housing 14. This prevents the material of the fuse 2, for example aluminum, from being distributed in the battery cell and reacting with the materials in the battery cell in the event of melting. This reduces the risk of thermal runaway of the battery cell.

[0029] The fuse 2 is advantageously covered by a polymer 1, for example an epoxy resin, on an outer surface facing away from the housing. The polymer 1 may be applied to the fuse 2 by a spraying process for example. The polymer 1 prevents formation of an electrical arc, in particular in the case of enrichment with an oxidant by forming nonconductive material, upon melting of the fuse 2. In addition, the polymer 1 protects the fuse 2 from mechanical damage and corrosion and increases mechanical stability.

[0030] To improve heat removal, the polymer 1 may be admixed with at least one filler (for example Al(OH).sub.3 or Al.sub.2O.sub.3). It is further advantageous when the filler contains oxidant (for example ammonium perchlorate (NH.sub.4ClO.sub.4)). In this case the oxidant can react with the liquefied aluminum of the fuse 2 to afford nonconductive aluminum oxide (Al.sub.2O.sub.3).

[0031] In a preferred embodiment, the lid 6 of the housing 14 is electrically insulated from the connection plate 4 of the positive terminal 11. This may be achieved when a seal 8, arranged between the electrically conductive rivet 7 and the housing lid 6, comprises an electrically insulating plastic. This avoids the possibility of failure of a resistor, which in conventional battery cells connects the housing with the positive terminal, in the case of an excessive current. If a conventional battery cell is serially connected to further battery cells in a battery module, a failure of the resistor through sudden interruption of the contact between the positive terminal and the housing can result in a risk of the voltage of at least one adjacent battery cell being applied to the battery cell and bringing about a polarity inversion of the affected battery cell. In this case a negative potential would be applied to the housing and could bring about unwanted chemical reactions such as for example deposition of lithium or copper in the battery cell. This could result in an internal shorting of the battery cell. The insulation of the positive terminal 11 from the housing 14 proposed here, in particular via the seal 8, makes it possible to reduce this risk.

[0032] Although the invention has been illustrated and described in detail using exemplary embodiments the invention is not limited by the exemplary embodiments. On the contrary, other variations of the invention may be derived therefrom without departing from the scope of protection of the invention defined by the claims.

TABLE-US-00001 List of reference numerals 1 Polymer 2 Fuse 3 Insulation 4 Electrically conductive connection plate 5 Insulating plate 6 Lid 7 Electrically conductive rivet 8 Seal 9 Current collector 10 Battery cell 11 Positive terminal 12 Negative terminal 13 Cover for rupture membrane 14 Housing