Methods of welding a bonding connector of a contact plate to a battery cell terminal
Embodiments are directed to establishing a direct electrical bond between a bonding connector of a contact plate and a battery cell in a battery module. In a first embodiment, an oscillating laser is used to weld the bonding connector to a battery cell terminal over a target area over which the bonding connector makes non-flush contact. In a second embodiment, the bonding connector is flattened to reduce a gap between the bonding connector and the target area on the battery cell terminal, and then laser-welded (e.g., using an oscillating or non-oscillating laser). In a third embodiment, at least one hold-down mechanism is applied over the bonding connector to secure the bonding connector to the battery cell terminal, after which the bonding connector is laser-welded to the battery cell terminal.
1. A method of establishing a direct electrical bond between a bonding connector of a contact plate and a battery cell in a battery module, comprising:
placing the bonding connector onto an external terminal surface of the battery cell with the bonding connector making non-flush contact with the external terminal surface; and
oscillating a laser over a target range that encompasses both a point of contact between the external terminal surface and the bonding connector as well as an area where a gap exists between the external terminal surface and the bonding connector due to the non-flush contact,
wherein the oscillating results in the bonding connector being welded onto the external terminal surface over the target range.
2. The method of claim 1 ,
wherein the external terminal surface corresponds to a positive terminal of the battery cell, or
wherein the external terminal surface corresponds to a negative terminal of the battery cell.
3. The method of claim 2 , wherein the oscillating uses a soldering compound.
4. The method of claim 3 , wherein the soldering compound includes a reactive e multi-layer foil.
5. The method of claim 1 , further comprising:
applying at least one hold-down mechanism to secure the bonding connector onto the external terminal surface, the at least one hold-down mechanism including a magnetic-based hold-down mechanism; and
laser-welding, during the applying, the placed bonding connector to the external terminal surface.
6. The method of claim 5 , wherein the applying includes:
placing a magnet in proximity to the battery cell in the battery module prior to the laser-welding.
7. The method of claim 6 , further comprising:
removing the magnet from the battery module after the laser-welding.
8. The method of claim 6 , wherein the magnet is placed beneath the battery cell in the battery module prior to the laser-welding.
9. The method of claim 5 , wherein the applying includes:
magnetizing the battery cell prior to the battery cell being inserted into the battery module.
10. The method of claim 9 , wherein the magnetizing includes:
passing the battery cell through a magnetic coil prior to the battery cell being inserted into the battery module.
11. The method of claim 5 , wherein the at least one hold-down mechanism further includes a hold-down plate.
12. The method of claim 1 ,
applying a hold-down plate to secure the bonding connector onto the external terminal surface,
wherein the hold-down plate includes protrusions that are configured to be placed over a set of bonding connectors of the contact plate such that downward force results in the set of bonding connectors being bent downwards so as to be pressed down onto a corresponding set of external terminal surfaces.
13. The method of claim 12 , wherein the hold-down plate includes one or more elastic elements to protect one or more components of the battery module as the downward force is applied.
14. The method of claim 12 , wherein the placing includes:
aligning one of the protrusions of the hold-down plate with the bonding connector before the bonding connector is in contact with the external terminal surface of the battery cell, and
bending the bonding connector downwards by applying a downward force to the hold-down plate at least until the aligned protrusion presses the bonding connector into contact with the external terminal surface of the battery cell.