Method for producing an electrochemical bundle of a lithium battery

1. A process for producing an electrochemical bundle of a lithium accumulator, wherein the accumulator is a Li-ion accumulator, with a view to its electrical connection to the output terminals of the accumulator, including the following steps:

a/ providing an electrochemical bundle including at least one electrochemical cell consisting of a cathode and an anode on either side of a separator suitable for being impregnated with an electrolyte, the bundle having a shape that is elongate along a longitudinal axis X 1 , having, at one of its lateral ends, anode bands that are not coated and, at the other of its lateral ends, cathode bands that are not coated;

b/ folding with plastic deformation, at least in a direction radial to the axis X 1 , a portion of the bands from the exterior to the interior of the electrochemical bundle, onto an area portion of at least one of the lateral ends so that at least two consecutive bands overlap in their folded portion and so that the folded portions that overlap form a substantially flat area; and

c/ axial tamping along the axis of the bands of the electrochemical bundle, of at least the area portion of the lateral end that is not folded in step b/, the axial tamping being carried out repeatedly so as to obtain in the tamped and not folded area portion of the lateral end, a substantially flat plinth intended to be welded to a current collector.

2. The process for producing an electrochemical bundle as claimed in claim 1 , the folding in step b/ and the axial tamping in step c/ being carried out at each of the lateral ends.

3. The process for producing an electrochemical bundle as claimed in claim 1 , the thickness of the band portions folded onto a lateral end being smaller than 0.6 mm.

4. The process for producing an electrochemical bundle as claimed in claim 1 , the axial tamping in step c/ being carried out on the entire area of a lateral end of the bundle.

5. The process for producing an electrochemical bundle as claimed in claim 1 , the electrochemical bundle consisting of a single electrochemical cell being wound upon itself by spooling.

6. The process for producing an electrochemical bundle as claimed in claim 5 , the folding in step b/ being carried out along at least one straight line passing through the center of the roll of the cell.

7. The process for producing an electrochemical bundle as claimed in claim 5 , the folding in step b/ being carried out along at least one straight line not passing through the center of the roll of the cell.

8. The process for producing an electrochemical bundle as claimed in claim 1 , in which a step d/ is carried out of welding together folded band portions of a given lateral end.

9. The process for producing an electrochemical bundle as claimed in claim 8 , the welding step d/ being carried out between the step b/ of radial folding and the step c/ of axial tamping.

10. The process for producing an electrochemical bundle as claimed in claim 8 , the welding step d/ consisting in obtaining a weld by ultrasonic, electric or laser welding.

11. A process for producing an electrical connection portion between an electrochemical bundle of a lithium accumulator and one of the output terminals of the accumulator, including the following steps:

producing an electrochemical bundle according to the process as claimed in claim 1 ;

welding together folded band portions of the electrochemical bundle of a given lateral end according to step d/ that is carried out of welding together folded band portions of a given lateral end; and

welding the plinth obtained to a current collector itself intended to be electrically connected or coupled to an output terminal of the accumulator.

12. The process for producing an electrical connection portion as claimed in claim 11 , in which the welding step d/ and the step of welding the plinth to a current collector are carried out simultaneously.

13. The process for producing an electrical connection portion as claimed in claim 12 , prior to the simultaneous welding steps, a current collector is brought into contact against the plinth, the current collector including:

one or more contact ribs suitable for making contact against the plinth; and

one or more apertures bounded by holding tabs suitable for holding in place the folded band portions of the electrochemical bundle.

14. The process for producing an electrical connection portion as claimed in claim 12 , the simultaneous welding steps being carried out by laser welding.