Interconnector for wire bonding in battery packs

Abstract

An interconnector (200) for connecting a plurality of cells (110) in a battery pack (100) is provided. The interconnector (200) includes a primary interconnect segment (210) for connecting the plurality of cells (110) and a plurality of wire bonds (220) for connecting the primary interconnect segment (210) to terminals (112) of the plurality of cells (110). The primary interconnect segment (210) has a plurality of openings (212) adapted to the respective terminals (112) of the plurality of cells (110). Each of the plurality of wire bonds (220) is connected at one end to a respective terminal (112) of the plurality of cells (110) and at the other end to a plurality of connection portions (214) on the primary interconnect segment (210). The interconnector (200) further includes a signal output sub-segment (230) and a bus bar segment (240). The interconnect (200) provides efficiency and safety to the battery pack (100).

Description

[Technical field]

[0001] The present invention relates to a battery pack, and more particularly to an interconnector for connecting cells in a battery pack. [Background technology]

[0002] It is known in the art to achieve any desired voltage or current in a battery pack by connecting multiple cells, such as lithium-ion or nickel-metal hydride cells, in series or parallel. For example, a set of cells can be placed in parallel to achieve a desired current. As a result, multiple parallel sets can be coupled in series to achieve a larger set of the desired voltage. The larger set can be electrically coupled in series or parallel with other similarly sized sets to achieve even higher voltages or currents.

[0003] In the prior art, resistance spot welding is utilized as a joining technique for electrically joining the cells to each other. The resistance spot welding process has many drawbacks, as it is time-consuming and prone to failure. Furthermore, battery packs utilizing spot welding are only suitable for low power applications. Although spot welding is a low capital investment means to implement, it brings about several problems with cell connection and thermal design.

[0004] In addition, resistance spot welding makes it difficult to check the quality of the connection between each cell and the conductor. Furthermore, there is no provision for electrical protection. The problem of one cell malfunctioning or having an electrical short circuit making the entire battery set unusable has been a problem in the prior art.

[0005] Moreover, in the prior art configuration, the short circuit problem is exacerbated and even more severe. A short circuit generates heat. This heat resulting from a short circuit in some of the batteries can be fatal to other non-shorted batteries. Batteries are packaged closely together in a battery pack, and even non-shorted batteries can overheat due to being in close proximity to other shorted batteries. An overheated battery can easily explode, with catastrophic results. Thus, a minor short circuit in only one of the batteries can have catastrophic results in the entire set and even in the battery management system. Furthermore, the heat resulting from a short circuit creates temperature gradients in the cells in the battery pack, leading to greater imbalances. Furthermore, manual spot welding can result in inconsistent quality. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, there is a need in the art to provide a connection system for cells in a battery pack that at least addresses the aforementioned problems. [Means for solving the problem]

[0007] In one aspect, the present invention relates to an interconnect for connecting a plurality of cells in a battery pack. The interconnect comprises a primary interconnect segment and a plurality of wire bonds. The primary interconnect segment connects the plurality of cells. The primary interconnect segment has a plurality of openings between a first end and a second end adapted to respective terminals of the plurality of cells in the battery pack. The plurality of wire bonds connect the primary interconnect segment to the terminals of the plurality of cells. Each of the plurality of wire bonds is connected at one end to a respective terminal of the plurality of cells and at the other end to a plurality of connection portions on the primary interconnect segment. The plurality of connection portions are located substantially near the respective terminals of the plurality of cells.

[0008] In one embodiment, the interconnect has a signal output subsegment at a first end of the main interconnect segment. The signal output subsegment is joined to the main interconnect segment and provides information regarding the state of the plurality of cells. In one embodiment, the signal output subsegment is made from nickel and has a means for connecting to an external monitoring device.

[0009] In another embodiment, the interconnector has a busbar segment extending substantially parallel to the primary interconnect segment. The busbar segment is joined to the primary interconnect segment and extends toward and beyond a first end of the primary interconnect segment to provide a means for power output of the multiple cells. Additionally, the interconnector includes at least one side branch portion connecting the primary interconnect segment to the busbar segment. The at least one side branch portion connects the primary interconnect segment to the busbar segment at a first location on the primary interconnect segment.

[0010] In a further embodiment, the plurality of apertures of the interconnect comprises a first set of apertures and a second set of apertures. The first set of apertures is arranged substantially linearly and extends parallel to the second set of apertures. The first set of apertures is adapted to a right terminal of each of the first set of cells in the plurality of cells. The second set of apertures is adapted to a left terminal of each of the second set of cells in the plurality of cells. The left terminal has a polarity opposite to that of the right terminal. The first set of cells and the second set of cells form an array of cells in the battery pack.

[0011] In another embodiment, each of the plurality of wire bonds is an electrical fuse designed to disconnect / break when the current passing through any of the plurality of wire bonds exceeds a predetermined current value, the predetermined current value being dependent on the dimensions and material of the wire bond.

[0012] In various embodiments, the interconnect is made from two or more types of metals, such as, for example, copper and nickel.

[0013] Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying drawings, which are intended to be illustrative, and not limiting, and while the invention will be broadly described in the context of these embodiments, it will be understood that it is not intended to limit the scope of the invention to these particular embodiments. [Brief description of the drawings]

[0014] [Figure 1A] 1 is a schematic diagram of a battery pack according to one embodiment of the present invention; [Figure 1B] 1 is a schematic diagram of a battery pack according to an embodiment of the present invention; [Figure 2A] 1A-1D are diagrams illustrating an interconnect according to various embodiments of the present invention; [Figure 2B] 1A-1D are diagrams illustrating an interconnect according to various embodiments of the present invention; [Figure 2C] 1 is an interconnect according to various embodiments of the present invention;FIG. 2 is an interconnect according to another embodiment of the present invention; [Figure 3A] 1A-1D show various views of an interconnect according to one embodiment of the present invention; [Figure 3B] 1A-1D show various views of an interconnect according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention relates to a battery pack, and more particularly to an interconnect for connecting cells in a battery pack.

[0016] 1A and 1B show schematic diagrams of a battery pack 100 according to an embodiment of the present invention. FIG. 1A shows a top view of the battery pack 100 and further shows a close-up view of a portion 212 of the interconnect. FIG. 1B shows a perspective view of the battery pack 100. The battery pack comprises a plurality of cells 110 arranged in an array to form the battery pack 100. The plurality of cells 100 are electrically coupled in series and then in parallel to achieve a desired voltage and current of the battery pack 100. A first set 110f of cells are arranged and electrically connected in parallel. Similarly, a second set 110s of cells are connected in parallel. The first set 110f is then electrically connected in series to the second set 110s of cells, and so on. The electrical connections between the plurality of cells are achieved by using a plurality of interconnects 200.

[0017] 2A-2C show an interconnector 200 according to various embodiments of the present invention. FIG. 2A and FIG. 2B show an interconnector 200 according to one embodiment of the present invention from various perspectives. FIG. 2AB shows a front view of the interconnector 200. FIG. 2AC shows a side view of the interconnector 200. FIG. 2AD shows a top view of the interconnector 200. FIG. 2C shows an interconnector 200 according to another embodiment of the present invention. Referring to FIG. 2A and FIG. 2B, the interconnector 200 comprises a main interconnect segment 210 and a number of wire bonds 220. The main interconnect segment 210 connects a number of cells 110. The main interconnect segment 210 has a number of openings 212 between a first end 210f and a second end 210s of the main interconnect segment 210. These openings 212 are adapted to the respective terminals 112 of the cells 110 in the battery pack 100.

[0018] A plurality of wire bonds 220 connect the primary interconnect segment 210 to the terminals 112 of the plurality of cells 110. Each of the plurality of wire bonds 220 is connected at one end to a respective terminal 112 of the plurality of cells 110 and at the other end to a plurality of connection portions 214 on the primary interconnect segment 210. The plurality of connection portions 214 are located substantially near the respective terminals 112 of the plurality of cells 110. Wire bonding is an ultrasonic metal-to-metal friction welding process that is performed at room temperature and no external heat is required for welding.

[0019] In one embodiment, the interconnect 200 comprises a signal output subsegment 230 at a first end 210f of the main interconnect segment 210. The signal output subsegment 230 is joined to the main interconnect segment 210 and provides information regarding the status of the plurality of cells 110. The signal output subsegment 230 is made from nickel and has means for connecting to external monitoring equipment.

[0020] In one embodiment, the interconnector 200 comprises a busbar segment 240 extending substantially parallel to the primary interconnect segment 210. The busbar segment 240 is joined to the primary interconnect segment 210 and extends toward and beyond a first end 210f of the primary interconnect segment 210 to provide a means for power output of the plurality of cells 110. The interconnector 200 also comprises at least one side branch portion 250 connecting the primary interconnect segment 210 to the busbar segment 240. The at least one side branch portion 250 connects the primary interconnect segment 210 to the busbar segment 240 at a first location on the primary interconnect segment 210.

[0021] 2C, in one embodiment, the plurality of apertures 212 comprises a first set of apertures 212f and a second set of apertures 212s. The first set of apertures 212f is arranged substantially linearly and extends parallel to the second set of apertures 212s. The first set of apertures 212f is adapted to a respective right terminal 112r, as shown in FIG. 1A, of the first set of cells 110f of the plurality of cells 110. Similarly, the second set of apertures 212s is adapted to a respective left terminal 112l of the second set of cells 110s of the plurality of cells 110. The left terminal 112l has a polarity opposite to that of the right terminal 112r. For example, the left terminal 112l has a positive polarity, and the right terminal has a negative polarity.

[0022] In one embodiment, each of the plurality of wire bonds 220 functions as an electrical fuse designed to disconnect / break if the current passing through any of the plurality of wire bonds 220 exceeds a predetermined current value. The predetermined current value depends on design aspects of the battery pack 200, such as the number of cells, voltage, current, connected load, age of the cells, and duration of use. The wire bonds 220 can be designed and selected with respect to dimensions and materials based on the required predetermined current value and safety factors according to these design aspects.

[0023] Figures 3A and 3B show an interconnect 200 from various perspectives according to various different embodiments of the present invention. Figure 3AA shows a perspective view of the interconnect 200. Figure 3AB shows a top view of the interconnect 200. Figure 3AC shows a front view of the interconnect 200. Figure 3BA shows a perspective view of the interconnect 200. Figure 3BB shows a top view of the interconnect 200. Figure 3BC shows a front view of the interconnect 200.

[0024] In one embodiment shown in Figure 3A, the interconnector 200 has only a main interconnect segment 210 and a signal output sub-segment 230. Alternatively, according to another embodiment in Figure 3B, the interconnector 200 has only a main interconnect segment 210 and a busbar segment 240. Thus, the interconnector 200 provides a modular structure according to the arrangement of the cells 110 in the array of the battery pack 100.

[0025] In various embodiments of the present invention, the interconnector 200 is made from two or more types of metals, such as copper and nickel. For example, the main interconnect segment 210 and the bus bar segment 240 are made from copper, and the signal output sub-segment 230 is made from nickel.

[0026] Advantageously, the interconnect provided by the present invention eliminates the need to use spot welding to connect the cells together, making the battery safer against overcurrent and short circuits. The problem of loose wires inherent in spot welding techniques, which is the main cause of short circuits, is avoided by using wire bonding. These wires act as fuses, so that if any cell behaves abnormally, they will disconnect and disconnect that cell from the battery pack, notifying the user about the pack and reducing the possibility of thermal runaway.

[0027] Additionally, the present invention improves thermal management in the battery pack and avoids quality issues inherent with manual spot welding by allowing the wire bonding process to be performed at room temperature and eliminating the need for external heat. Additionally, wire bonding has the advantages of single and double sided welding, improving thermal management of the battery pack and making the pack lighter for better handling and packaging.

[0028] Furthermore, the interconnects provided by the present invention are retrofittable and do not interfere with the fabrication of cell holders and other sub-components to provide effective bonding between the interconnects and the cells.

[0029] The present invention also improves heat management in the battery pack, avoiding quality issues inherent in manual spot welding, and reduces the weight of the battery pack.

[0030] Additionally, the present invention provides a modular interconnect structure rather than a single plate, which improves usability of the battery pack.

[0031] Although the present invention has been described with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. An interconnector (200) for connecting a plurality of cells (110) in a battery pack (100), comprising: a primary interconnect segment (210) for connecting the plurality of cells (110), the primary interconnect segment (210) having a plurality of openings (212) between a first end (210f) and a second end (210s) of the primary interconnect segment (210), the plurality of openings (212) adapted to respective terminals (112) of the plurality of cells (110) in the battery pack (100); a plurality of wire bonds (220) for connecting the main interconnect segment (210) to the terminals (112) of the plurality of cells (110), each of the plurality of wire bonds (220) being connected at one end to the terminals (112) of each of the plurality of cells (110) and at the other end to a plurality of connection portions (214) on the main interconnect segment (210), the plurality of connection portions (214) being located substantially near the terminals (112) of each of the plurality of cells (110); The interconnect (200) comprises:

2. 2. The interconnector (200) of claim 1, comprising a signal output subsegment (230) at the first end (210f) of the main interconnect segment (210), the signal output subsegment (230) being joined to the main interconnect segment (210) to provide information regarding a status of the plurality of cells (110).

3. The interconnect (200) of claim 2, wherein said signal output subsegment (230) is made from nickel and has means for connecting to an external monitoring device.

4. 2. The interconnector (200) of claim 1, comprising a busbar segment (240) extending substantially parallel to the main interconnect segment (210), the busbar segment (240) being joined to the main interconnect segment (210) and extending toward and beyond the first end (210f) of the main interconnect segment (210) to provide a means for power output of the plurality of cells (110).

5. 5. The interconnector (200) of claim 4, comprising at least one side branch portion (250) connecting the main interconnect segment (210) to the busbar segment (240), the at least one side branch portion (250) connecting the main interconnect segment (210) to the busbar segment (240) at a first location on the main interconnect segment (210).

6. 2. The interconnector of claim 1, wherein the plurality of apertures comprises a first set of apertures and a second set of apertures, the first set of apertures being arranged substantially linearly and extending parallel to the second set of apertures, the first set of apertures being adapted to a respective right terminal of a first set of cells among the plurality of cells, and the second set of apertures being adapted to a respective left terminal of a second set of cells among the plurality of cells, the left terminal having an opposite polarity to the right terminal, and the first set of cells and the second set of cells form an array of cells in the battery pack.

7. 2. The interconnect (200) of claim 1, wherein each of the plurality of wire bonds (220) is an electrical fuse designed to disconnect / break when a current passing through any of the plurality of wire bonds (220) exceeds a predetermined current value.

8. The interconnect (200) of claim 7, wherein the predetermined current value is dependent on dimensions and material of the wirebonds (220).

9. The interconnect (200) of claim 1, wherein the interconnect (200) is made from two or more types of metals.

10. The interconnect (200) of claim 9, wherein one of the metals is selected from the group consisting of copper and nickel.

Images