Multilayered flexible battery interconnects and methods of fabricating thereof
Provided are multilayered flexible battery interconnects for interconnecting batteries in battery packs and methods of fabricating thereof. A multilayered flexible battery interconnect comprises insulating layers and two conductive layers, stacked together and positioned between the insulating layers. One conductive layer is thicker than the other. The thinner conductive layer comprises flexible tabs for connecting to batteries and, in some examples, comprises voltage sense traces. The smaller thickness of these flexible tabs ensures welding quality and allows using less energy during welding. The battery cell contacts, to which these flexible tabs are welded, can be significantly thicker. Furthermore, the smaller thickness enables fusible link integration into flexible tabs. At the same time, the two conductive layers collectively conduct current within the interconnect, with the thicker layer enhancing the overall current-carrying capacity. The two conductive layers can be welded together to ensure electric connections and mechanical support.
1. A multilayered flexible battery interconnect for interconnecting batteries in a battery pack, the multilayered flexible battery interconnect comprising:
a first insulating layer;
a second insulating layer comprising a support tab;
a first conductive layer, disposed between the first insulating layer and the second insulating layer and directly interfacing the first insulating layer; and
a second conductive layer, disposed between and directly interfacing each of the first conductive layer and the second insulating layer, wherein:
the first conductive layer is thicker than the second conductive layer,
the second conductive layer comprises a plurality of flexible tabs extending past the first conductive layer for connecting to the batteries,
the support tab supports one of the plurality of flexible tabs at least before connecting to the batteries, and
while connecting to the batteries, the one of the plurality of flexible tabs is configured to adhere to the support tab while the support tab is configured to separate from the remaining portion of the second insulating layer, or the one of the plurality of flexible tabs is configured to adhere to the support tab while the support tab is configured to bend out-of-plane relative to the remaining portion of the second insulating layer; and
a voltage trace formed from a third conductive layer, wherein:
the second insulating layer extends between the third conductive layer and the second conductive layer and comprises a second-insulating layer opening,
the voltage trace is connected to the second conductive layer through the second-insulating layer opening,
the second conductive layer is connected to the first conductive layer, and
the first conductive layer forms bus bars such that one of the bus bars is electrically connected to the voltage trace.
2. The multilayered flexible battery interconnect of claim 1 , wherein the first conductive layer is at least twice thicker than the second conductive layer.
3. The multilayered flexible battery interconnect of claim 1 , wherein:
the first conductive layer has a thickness of at least 300 micrometers; and
the second conductive layer has a thickness of less than 150 micrometers.
4. The multilayered flexible battery interconnect of claim 1 , wherein both the first conductive layer and the second conductive layer are formed from aluminum.
5. The multilayered flexible battery interconnect of claim 1 , wherein the first conductive layer and the second conductive layer are formed from different materials.
6. The multilayered flexible battery interconnect of claim 1 , wherein the first conductive layer and the second conductive layer are welded together at multiple welded locations, separated from each other.
7. The multilayered flexible battery interconnect of claim 6 , wherein:
the second insulating layer comprises welding openings; and
each of the multiple welded locations is positioned within one of the welding openings.
8. The multilayered flexible battery interconnect of claim 1 , wherein:
the first conductive layer has a uniform thickness throughout an entire boundary of the first conductive layer; and
the second conductive layer has a uniform thickness throughout an entire boundary of the second conductive layer.
9. The multilayered flexible battery interconnect of claim 1 , wherein:
the plurality of flexible tabs comprises a first tab set extending in a first direction; and
the plurality of flexible tabs comprises a second tab set extending in a second direction, opposite to the first direction.
10. The multilayered flexible battery interconnect of claim 9 , wherein:
any two adjacent tabs in the first tab set are spaced apart by a battery pitch of the battery pack; and
any two adjacent tabs in the second tab set are spaced apart by the battery pitch of the battery pack.
11. The multilayered flexible battery interconnect of claim 10 , wherein:
each the plurality of flexible tabs comprises a contact pad and a fusible link, connecting and supporting the contact pad relative to a remaining part of the second conductive layer; and
the contact pad is configured to connect to a center contact of one of the batteries.
12. The multilayered flexible battery interconnect of claim 11 , wherein:
the second insulating layer comprises a contact opening; and
the fusible link and a majority of the contact pad protrude into the contact opening.
13. The multilayered flexible battery interconnect of claim 12 , wherein:
the support tab, at least partially defines the contact opening; and
a portion of the contact pad is adhered to the support tab.
14. The multilayered flexible battery interconnect of claim 13 , wherein:
the second insulating layer comprises a flexibility slit, extending along an interface between the support tab and a remaining portion of the second insulating layer.
15. The multilayered flexible battery interconnect of claim 9 , wherein:
any two adjacent tabs in the first tab set are spaced apart by a battery pitch or a double of the battery pitch of the battery pack; and
any two adjacent tabs in the second tab set are spaced apart by a battery pitch or a double of the battery pitch of the battery pack.
16. The multilayered flexible battery interconnect of claim 15 , wherein:
each tab in the first tab set and the second tab set comprises a contact pad and a flexible neck, connecting and supporting the contact pad relative to a remaining part of the tab; and
the contact pad is configured to simultaneously connect to edge contacts of two adjacent ones of the batteries.
17. The multilayered flexible battery interconnect of claim 16 , wherein:
the second insulating layer comprises a contact opening; and
the flexible neck and a majority of the contact pad protrude into the contact opening.
18. The multilayered flexible battery interconnect of claim 17 , wherein:
the support tab at least partially defines the contact opening; and
a portion of the contact pad is adhered to the support tab.
19. The multilayered flexible battery interconnect of claim 18 , wherein:
the second insulating layer comprises a flexibility slit, extending along an interface between the support tab and a remaining portion of the second insulating layer.
20. The multilayered flexible battery interconnect of claim 1 , wherein the first insulating layer and the second insulating layer directly adhere to each other forming a boundary around portions of the first conductive layer and the second conductive layer.
21. The multilayered flexible battery interconnect of claim 1 , further comprising a third insulating layer that isolates the voltage trace from environment and supports the voltage trace relative to the second insulating layer.
22. The multilayered flexible battery interconnect of claim 1 , wherein the second insulating layer further comprises a flexibility slit extending along an interface between the support tab and a remaining portion of the second insulating layer.
23. The multilayered flexible battery interconnect of claim 1 , wherein, while connecting to the batteries, the one of the plurality of flexible tabs is configured to adhere to the support tab while the support tab is configured to separate from the remaining portion of the second insulating layer.
24. The multilayered flexible battery interconnect of claim 1 , wherein, while connecting to the batteries, the one of the plurality of flexible tabs is configured to adhere to the support tab while the support tab is configured to bend out-of-plane relative to the remaining portion of the second insulating layer.