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EP-4496107-B1 - RECHARGEABLE BATTERY MODULE

EP4496107B1EP 4496107 B1EP4496107 B1EP 4496107B1EP-4496107-B1

Inventors

  • LEE, HYEOK
  • KWON, YOUNG-HWAN

Dates

Publication Date
20260513
Application Date
20240715

Claims (14)

  1. A rechargeable battery module comprising: a busbar holder (20) covering a plurality of battery cells (10); a busbar disposed on the busbar holder (20) to electrically connect the battery cells (10); and a flexible printed circuit (40, 50, 60, 80, 90, 98) attached to the busbar, the flexible printed circuit (40, 50, 60, 80, 90, 98) being configured to send a signal and to detect a current in the busbar, the flexible printed circuit (40, 50, 60, 80, 90, 98) including a thin copper film attached between inner surfaces of a pair of cover layers (41, 42), wherein the thin copper film is exposed in unit thin film portions (43, 53, 63, 83, 93, 96) through a plurality of openings (411, 421) formed in the pair of cover layers (41, 42), characterised in that the thin copper film and the pair of cover layers (41, 42) are bent, and wherein the unit thin film portions (43, 53, 63, 83, 93, 96) form multiple layers and are welded to the busbar.
  2. The rechargeable battery module of claim 1, wherein each unit thin film portion has a thickness of 0.035 mm, and wherein a thickness of the multiple layers is equal to 0.035 mm multiplied by the number of layers.
  3. The rechargeable battery module of one of claims 1 or 2, wherein the flexible printed circuit (40, 50, 60, 80, 90, 98) comprises: a main line portion (44, 54) disposed in a first direction on the busbar holder (20); and a branch line portion (45, 55) protruding from the main line portion (44, 54) in a second direction intersecting the first direction, and disposed further in the first direction, and wherein the unit thin film portions (43, 53) are connected to the branch line portion (45, 55).
  4. The rechargeable battery module of claim 3, wherein the branch line portion (55) is attached to the busbar.
  5. The rechargeable battery module one of claims 3 or 4, wherein the rechargeable battery module has two unit thin film portions (43) connected in the first direction, wherein the unit thin film portions (43) comprise a first unit portion (431) and a second unit portion (432) continuously extending along the first direction, and wherein the first unit portion (431) and the second unit portion (432) are bent around a second direction bending axis set in the second direction such that the first unit portion (431) and the second unit portion (432) overlap with each other.
  6. The rechargeable battery module of claim 5, wherein the first unit portion (431) comprises a first plane portion (F1) connected to a first inclined portion (S1) at a first inclined angle θ1, wherein the second unit portion (432) comprises a second plane portion (F2) connected to a second inclined portion (S2) at a second inclined angle θ2 that is greater than the first inclined angle θ1, and wherein the first plane portion (F1) and the second plane portion (F2) are connected in the second direction, are sequentially stacked on the busbar, and are welded to the busbar.
  7. The rechargeable battery module of one of claims 3 or 4, wherein the rechargeable battery module comprise two of the unit thin film portions (53, 63) connected in the second direction, wherein the unit thin film portions (53, 63) comprise a first unit portion (531, 631) and a second unit portion (532, 632) continuously extending along the second direction, and wherein the first unit portion (531, 631) and the second unit portion (532, 632) are bent around a first direction bending axis set in the first direction such that the first unit portion (531, 631) and the second unit portion (532, 632) overlap each other.
  8. The rechargeable battery module of claim 7, wherein the first unit portion (531, 631) comprises a first plane portion (F21, F31) connected to a first inclined portion (S21, S31) at a first inclined angle θ21, wherein the second unit portion (532, 632) comprises a second plane portion (F22, F32) connected to a second inclined portion (S22, S32) at a second inclined angle θ22 that is greater than the first inclined angle θ21, and wherein the first plane portion (F21, F31) and the second plane portion (F22, F32) are connected in the first direction, are sequentially stacked on the busbar, and are welded to the busbar.
  9. The rechargeable battery module of one of claims 3 or 4, wherein the rechargeable battery module has three of the unit thin film portions (63) connected in the second direction, wherein the unit thin film portions (63) comprise a first unit portion (631), a second unit portion (632), and a third unit portion (633) continuously extending along the second direction, wherein the first unit portion (631) and the second unit portion (632) are bent around a first direction bending axis set in the first direction such that the first unit portion (631) and the second unit portion (632) overlap with each other, and wherein the second unit portion (632) and the third unit portion (633) are bent around another first direction bending axis set in the first direction such that the second unit portion (632) and the third unit portion (633) overlap with each other.
  10. The rechargeable battery module of claim 9, wherein the first unit portion (631) comprises a first plane portion (F31) connected to a first inclined portion (S31) at a first inclined angle θ31, wherein the second unit portion (632) comprises a second plane portion (F32) connected to a second inclined portion (S32) at a second inclined angle θ32 that is greater than the first inclined angle θ31, wherein the third unit portion (633) comprises a third plane portion (F33) connected to a third inclined portion (S33) at a third inclined angle θ33 that is greater than the second inclined angle θ32, and wherein the first plane portion (F31), the second plane portion (F32), and the third plane portion (F33) are connected in the second direction, are sequentially stacked on the busbar, and are welded to the busbar.
  11. The rechargeable battery module of one of claims 3 or 4, wherein the rechargeable battery module has three of the unit thin film portions connected in the first direction, wherein the unit thin film portions comprise a first unit portion (831), a second unit portion (832), and a third unit portion (833) continuously extending along the first direction, wherein the first unit portion (831) and the second unit portion (832) are bent around a second direction bending axis set in the second direction such that the first unit portion (831) and the second unit portion (832) overlap with each other, and wherein the second unit portion (832) and the third unit portion (833) are bent around another second direction bending axis set in the second direction such that the second unit portion (832) and the third unit portion (833) overlap with each other.
  12. The rechargeable battery module of one of claims 3 or 4, wherein the unit thin film portions (93) comprise a first unit portion (931), a second unit portion (932), a third unit portion (933), and a fourth unit portion (934) continuously extending along the first direction, wherein the first unit portion (931) and the second unit portion (932) are bent around a second direction bending axis set in the second direction such that the first unit portion (931) and the second unit portion (932) overlap with each other, wherein the second unit portion (932) and the third unit portion (933) are bent around another second direction bending axis set in the second direction such that the second unit portion (932) and the third unit portion (933) overlap with each other, and wherein the third unit portion (933) and the fourth unit portion (934) are bent around the other second direction bending axis set in the second direction such that the third unit portion (933) and the fourth unit portion (934) overlap with each other.
  13. The rechargeable battery module of one of claims 3 or 4, wherein the rechargeable battery module has four of the unit thin film portions connected in the first direction and the second direction.
  14. The rechargeable battery module of claim 13, wherein the unit thin film portions comprise a first unit portion (961) and a second unit portion (962) continuously extending along the first direction; and wherein the unit film portions comprise a third unit portion (963) and a fourth unit portion (964) continuously extending along the second direction, connected to the first unit portion (961) and the second unit portion (962), and continuously extending along the first direction.

Description

BACKGROUND OF THE INVENTION (a) Field of the Invention The present disclosure relates to a rechargeable battery module, and more particularly, to a rechargeable battery module that connects a sensing portion of a flexible printed circuit (FPC) to a busbar. (b) Description of the Related Art Unlike primary batteries, rechargeable batteries are batteries that can be repeatedly charged and discharged. Small-capacity rechargeable batteries are used in small, portable electronic devices such as mobile phones, laptop computers, and camcorders. High-capacity and high-density secondary batteries are used as power sources for driving motors in hybrid and electric vehicles or for energy storage. The rechargeable batteries may be used by forming a rechargeable battery module including a plurality of battery cells connected in series and/or parallel to drive a motor of, for example, a hybrid vehicle that requires relatively high energy density. The rechargeable battery module is equipped with a flexible printed circuit (FPC) that detects a voltage or current from the busbar and transmits a detection signal. The FPC sensing structure solders the FPC to a separate nickel tab (Ni-Tab) and welds the tab to an aluminum (Al) busbar. Nickel tabs (Ni- tab), however, are associated with increased costs because they require raw nickel, a soldering process to form junctions, a coating process to form an anticorrosion coating, and jigs for guides. Deformation (e.g., S deform) of the FPC causes sagging during movement due to the nickel tab. Such sagging in FPC can occur during the welding of the aluminum busbar and the nickel tab It is therefore difficult to form the in-position junction of the FPC and the nickel tab for the busbar. Examples may be found in WO 2018/124751 A1. SUMMARY OF THE INVENTION The present disclosure provides a rechargeable battery module capable of directly bonding of a flexible printed circuit (FPC) to a busbar. The present disclosure also provides a rechargeable battery module that enables in-position junction of the flexible printed circuit (FPC) to the busbar. A rechargeable battery module according to an embodiment of the present disclosure includes: a busbar holder covering a plurality of battery cells, a busbar disposed on the busbar holder to electrically connect the battery cells; and a flexible printed circuit (FPC) attached to the busbar for sending a signal and detecting a current in the busbar, wherein the flexible printed circuit includes a thin copper film attached between the inner surfaces of a pair of cover layers, wherein the thin copper film is exposed in (each of a plurality of) unit thin film portions through a plurality of openings formed in the pair of cover layers, the thin copper film and the pair of cover layers are bent, and the unit thin film portions are formed in multiple layers (e.g. the unit thin film portions form multiple layers) and welded to the busbar. The unit thin film portion has a thickness of 0.035 mm, and the total thickness of the multiple layers is equal to 0.035 mm multiplied by the number of layers. The flexible printed circuit includes: a main line portion disposed in a first direction on the busbar holder; and a branch line portion protruding from the main line portion in a second direction intersecting the first direction, and disposed further in the first direction. The unit thin film portions may be connected to the branch line portion. The branch line portion is attached to the busbar. In some embodiments, the rechargeable battery module has two unit thin film portions connected in the first direction. The unit thin film portions may include a first unit portion and a second unit portion continuously extending along the first direction, and the first unit portion and the second unit portion may be bent and overlapped with each other around a second direction bending axis set in the second direction. The first unit portion may include a first plane portion connected to a first inclined portion at a first inclined angle θ1, the second unit portion may include a second plane portion connected to a second inclined portion at a second inclined angle θ2 that is greater than the first inclined angle, and the first plane portion and the second plane portion may be connected in the second direction, sequentially stacked on the busbar, and welded to the busbar. In some embodiments, the rechargeable battery module has two unit thin film portions connected in the second direction. The unit thin film portions may include a first unit portion and a second unit portion continuously extending along the second direction, and the first unit portion and the second unit portion may be bent and overlapped with each other around a first direction bending axis set in the first direction. The first unit may include a first plane portion connected to the first inclined portion at a first inclination angle θ21, the second unit portion may include the second plane portion connected