Separator for a battery cell and battery cell providing such a separator

Abstract

The present invention relates to a separator arrangement (20) for an electrochemical battery cell (10) comprising an ionically conductive and electrically insulating separator layer (22), characterized in that the separator arrangement (20) further comprises a reduction layer (24) comprising a reductant, wherein the reduction layer (24) has a specific surface area which is in a range of not less than 10 m.sup.2/g, preferably of not less than 100 m.sup.2/g, for example of not less than 1000 m.sup.2/g, and wherein the reduction layer (24) is porous and has an open porosity in a range from not less than 10% to not more than 90%, preferably from not less than 30% to not more than 70%.

Claims

1. An electrochemical battery cell comprising: an anode; a cathode; and a separator arrangement between the anode and the cathode, the separator arrangement including: an ionically conductive and electrically insulating separator layer; and a reduction layer consisting of a reduction material, wherein the reduction layer has a specific surface area which is not less than 10 m.sup.2/g, and wherein the reduction layer is porous and has an open porosity in a range from not less than 30% to not more than 70%, wherein the reduction layer is made of a reduction material having a redox potential in a range of +0.16 V or less against the standard hydrogen electrode, wherein the reduction layer is provided with a porous protective layer on a side of the reduction layer opposite the separator layer, and wherein the protective layer is made of an electrically insulating material.

2. The battery cell as claimed in claim 1, characterized in that the reduction layer is disposed atop the surface of the separator layer.

3. The battery cell as claimed in claim 1, characterized in that the reduction layer is positioned between the separator layer and the anode.

4. The battery cell as claimed in claim 1, characterized in that the battery cell is a lithium-ion cell.

5. The battery cell as claimed in claim 1, wherein the reduction layer has a specific surface area which is not less than 100 m.sup.2/g.

6. The battery cell as claimed in claim 1, wherein the reduction layer has a specific surface area which is not less than 1000 m.sup.2/g.

7. The battery cell as claimed in claim 1, wherein the reduction layer is a porous metal layer.

8. The battery cell as claimed in claim 7, wherein the porous metal layer includes said reduction material selected from the group consisting of aluminum, titanium and nickel.

Description

DETAILED DESCRIPTION

(1) FIG. 1 shows a battery cell 10 comprising an anode 12 and a cathode 14. Provided adjacent to the anode 12 and in electrical contact therewith is a copper foil as current collector 16 and provided adjacent to the cathode 14 and in electrical contact therewith is an aluminum foil as current collector 18.

(2) A separator arrangement 20 is further provided between anode 12 and cathode 14. The separator arrangement 20 comprises an ionically conductive and electrically insulating separator layer 22 and a reduction layer 24, wherein the reduction layer 24 is made of a reduction material that may have a redox potential in a range of +0.16 V or less. The reduction layer may be made of a porous layer of titanium, aluminum or nickel for instance. It is further provided that the reduction layer 24 has a specific surface area which is in a range of not less than 10 m.sup.2/g, preferably of not less than 100 m.sup.2/g, for example of not less than 1000 m.sup.2/g, and wherein the reduction layer 24 is porous and has an open porosity in a range of not less than 10% to not more than 90%, preferably of not less than 30% to not more than 70%.

(3) FIG. 1 further shows that the reduction layer 24 is provided with a protective layer 26 on the side opposite the separator layer 22.

(4) The positive effect of the separator layer 20, i.e. of the battery cell 10 provided with the separator layer 20, is shown in FIGS. 2 and 3. FIG. 2 shows a discharged battery cell 10 in which a metallic impurity 28 is disposed in the cathode 14. During a charging operation the metallic impurity undergoes oxidative dissolution and diffuses as a metal ion in the direction of the separator arrangement 20 and contacts the reduction layer 24. The metal ion is reduced there and in turn deposited in elemental form as metal particle 30.