Battery module and battery pack comprising same

Abstract

The invention relates to a battery module and a battery pack comprising the same. The battery module includes a plurality of battery cells stacked in a longitudinal direction and a flexible interconnect configured to provide electrical information of the battery cells to a battery management unit. The flexible interconnect extends in a longitudinal direction and is secured to the plurality of battery cells, and includes a stress relief section that includes a plurality of interconnect traces and extends in the longitudinal direction. The stress relief section has a cutout extending in the longitudinal direction that separates adjacent interconnect traces from each other. The interconnect traces include a first peripheral interconnect trace forming a recessed portion and a second peripheral interconnect trace opposite the first peripheral interconnect trace and forming a protruding portion. A height of the protruding portion in the stress relief section is the same dimension as or less than a width of the flexible interconnect adjacent to the stress relief section.

Description

Technical Field

[0001] Aspects of embodiments of the present disclosure relate to battery modules. Background Art

[0002] Recently, vehicles that use electricity as a power source (e.g., vehicles for transporting goods and people) have been developed. Such electric vehicles are automobiles propelled by an electric motor using energy stored in a rechargeable (or secondary) battery. An electric vehicle can be powered solely by a battery or can be a hybrid vehicle powered by, for example, a gasoline generator (e.g., the vehicle can include a combination of an electric motor and a conventional internal combustion engine). Generally, an electric vehicle battery (EVB) (or traction battery) is a battery used to power the propulsion of a battery electric vehicle (BEV). Electric vehicle batteries are different from starting batteries, lighting batteries, and ignition batteries in that they are designed to provide (or output) power over a sustained period of time. A rechargeable (or secondary) battery differs from a primary battery in that it is designed to be repeatedly charged and discharged, while the latter provides an irreversible conversion of chemical energy to electrical energy. Low-capacity rechargeable batteries can be used as power sources for small electronic devices such as mobile phones, laptop computers, and video cameras, while high-capacity rechargeable batteries can be used as power sources for hybrid vehicles and the like.

[0003] Generally, a rechargeable battery pack includes an electrode assembly, a case that receives (or houses) the electrode assembly, and electrode terminals electrically connected to the electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. An electrolyte solution is injected into the case to enable the battery to be charged and discharged via an electrochemical reaction between the positive electrode, the negative electrode, and the electrolyte solution. The shape of the case (such as a cylindrical or rectangular shape) can vary based on the intended use of the battery. Lithium-ion (and similar lithium polymer) batteries (well known through their use in laptop computers and consumer electronics) are the most common type of battery used to power the latest electric vehicles under development.

[0004] A rechargeable battery can be used as a battery module that includes a plurality of unit battery cells (or is formed by a plurality of unit battery cells) (e.g., can be part of the battery module). The plurality of unit battery cells are combined in series and / or in parallel with each other to provide a high energy density, such as for motor drive in a hybrid vehicle. For example, a battery module can be formed by interconnecting the electrode terminals of a plurality of unit battery cells (the number of unit battery cells depends on the desired amount of electricity) to achieve a high-power rechargeable battery.

[0005] The battery module can be constructed in a block design or a modular design. In the block design, each cell is coupled to a common current collector structure and a common battery management system, and its units are arranged in a housing. In the modular design, a plurality of battery cells are connected to form a sub-module, and a number of sub-modules are connected to form a battery module. In automotive applications, the battery system typically consists of a plurality of battery modules connected in series with each other to provide a desired voltage. The battery module can include a sub-module having a plurality of stacked battery cells, and each stack can include parallel-connected cells (XpYs) connected in series in sequence or series-connected cells (XsYp) connected in parallel in sequence.

[0006] A battery pack is a group of any number (usually, the same) of battery modules. They can be configured in series, in parallel, or a combination of both to provide a desired voltage, capacity, or power density. The battery pack includes the individual battery modules and the interconnections that provide conductivity between them.

[0007] The battery system can include a battery management system (BMS), which is a suitable electronic system configured to manage rechargeable batteries, battery modules, and battery packs, such as by protecting the rechargeable batteries from operating outside their safe operating area, monitoring their state, calculating secondary data, reporting the data, controlling their environment, validating them, and / or balancing them. For example, the BMS can monitor the state of the rechargeable battery, which is represented by the following: voltage (e.g., the total voltage of the battery pack or battery module and / or the voltage of each individual cell), temperature (e.g., the average temperature of the battery pack or battery module, the coolant inlet temperature, the coolant outlet temperature, and / or the temperature of each individual cell), coolant flow (e.g., flow rate and / or coolant liquid pressure), and current. In addition, the BMS can calculate the following values based on the above parameters, such as the minimum and maximum cell voltages, the state of charge (SOC) or depth of discharge (DOD) used to indicate the charge level of the battery, the state of health (SOH; a measurement of various definitions of the percentage of the remaining capacity of the battery relative to the original capacity), the power state (SOP; the amount of electricity available within a defined time interval considering the current power usage, temperature, and other conditions), the safety state (SOS), the maximum charging current as the charge current limit (CCL), the maximum discharge current as the discharge current limit (DCL), and the internal impedance of the cell (e.g., for determining the open-circuit voltage).

[0008] The BMS can be centralized, such that a single controller is connected to the battery cells via multiple wires. In other cases, the BMS can be distributed, where BMS boards are mounted at each cell and there is only one communication cable between the battery and the controller. In other cases, the BMS can have a modular construction including several controllers, with each controller handling a certain number of cells (e.g., a group of cells) while communicating between the controllers. The centralized BMS is the most economical, but the least scalable and plagued by the need for multiple wires. The distributed BMS is the most expensive, but the simplest to install and provides the neatest components. The modular BMS offers a compromise of the features and drawbacks of the other two topologies.

[0009] The BMS can protect the battery pack from operating outside its safe operating region. Operation outside the safe operating region can be indicated by overcurrent, overvoltage (e.g., during charging), overtemperature, undertemperature, overpressure, and ground fault or leakage current detection. The BMS can prevent operation outside the safe operating region of the battery by including internal switches (e.g., relays or solid-state devices) that open if the battery is operating outside its safe operating region; requiring the devices to which the battery is connected to reduce or even terminate the use of the battery; and / or actively controlling the environment such as by heaters, fans, air conditioning, or liquid cooling.

[0010] Static control of the battery power output and charging may not be sufficient to meet the dynamic power demands of the various electrical devices connected to the battery system. Thus, a stable exchange of information between the controllers of the battery system and the electrical devices can be employed. Such information can include the actual state of charge (SoC), potential electrical performance, charging capacity, and internal resistance of the battery system, as well as the actual or predicted power demands or remaining charge of the electrical devices. Thus, the battery system can include a battery management system (BMS) for acquiring and processing such information at the system level, and can also include multiple battery module managers (BMMs) that are part of the battery modules of the system and acquire and process relevant information at the module level. The BMS measures the system voltage, system current, local temperatures at different locations inside the system housing, and the insulation resistance between the live components and the system housing, and the BMM can measure the individual cell voltages and temperatures of the battery cells in the battery module.

[0011] The BMS / BMM (also referred to as the battery management unit (BMU)) manages the battery pack by, for example, protecting the battery from operating outside its safe operating region (or safe operating parameters), monitoring its state, calculating secondary data, reporting the data, controlling its environment, validating it, and / or balancing it.

[0012] To manage or control the battery cells in a battery module or battery pack, several types of interconnections are utilized. The first type of interconnection is the so-called bus bar, which connects two or more terminals of the battery cells to provide a parallel or series configuration of the cells. Due to their nature of providing current to / from the cells, bus bars are solid and suitable for conducting high currents. Bus bars can have a strip shape with a large surface area. The large surface area can carry a large amount of current. In most applications, bus bars are passive components and can even be assembled in very small and narrow mounting spaces, but in some cases, they can be active components.

[0013] The second type of interconnection involves signal lines or wires, which are used to transfer the electrical information of the cells or sub-modules to the BMS / BMU. Due to their nature of carrying signals, these lines can be flexible (e.g., can be implemented as a flexible interconnection such as a flexible printed circuit (FPC)). Flexible interconnections are used inside the battery module to connect the battery cell terminals to the battery management unit. The flexible interconnection can extend over the bus bar, and in this case, the bus bar should have very smooth edges and surfaces, which are difficult to achieve and inspect. The flexible interconnection can be formed as a stack of an insulating (or dielectric) substrate material, a copper layer (from which multiple conductive traces or signal lines can be formed), and an insulating cover layer. The materials of the substrate and the cover layer can have relatively very good insulation properties, which can sufficiently isolate the signal lines while being relatively thin, such as in the range of dozens of micrometers. The insulating cover layer can be a thin layer of a mechanically durable insulating material (such as polyimide (PI)). Although the insulating material is durable from a mechanical perspective, due to its small thickness, it needs to be protected from hazards such as sharp edges, rough surfaces, stress, etc. In other words, this durability is limited by the layer thickness; in other words, a very thin layer with a single-digit micrometer thickness is fragile. Since it is desired to monitor the cell terminals and usually a large number of cells, the flexible interconnection can have a relatively large number of conductive traces, and each trace is connected to a cell terminal or a bus bar. In some cases, the cell terminals can be connected to the bus bar, which makes all the connected cell terminals have the same potential. In this sense, the flexible interconnection can be connected to the bus bar to obtain the potential of the cell terminals. If all the potentials of all the cell terminals are known, then the voltage of each cell is also known.

[0014] When a flexible interconnection is used to measure / balance the cell voltage, it mechanically interconnects the cell or the bus bar. Over time, mainly due to aging, the cells may expand, and thus, the cells should be able to expand in size. This dimensional change can be taken into account when designing the flexible interconnection such that the flexible interconnection can adequately compensate for the change in distance between two fixed points. In other words, the volume of the package of a cell may increase, which results in the movement of a single cell relative to another adjacent cell. Additionally, depending on the usage of the battery module, for example when used in a vehicle, the movement between cells may be caused by vibration. Therefore, since the flexible interconnection is typically arranged on top of the bus bar, the possibility of cell expansion can be considered when designing the flexible interconnection.

[0015] This can be achieved by using different methods. One method of compensating for the length change includes using an extra length and forming a waveform in the z-direction (e.g., the vertical direction), but this method results in difficult assembly. Another method includes creating a 2D shape for each individual interface, but this method produces more waste and does not accurately position the interconnection. In an example of the related art, flexibility is achieved by using an Ω shape in the z-direction of the flexible interconnection, an example of which is shown in Figure 2 For example, Figure 2 shows a typical implementation of a flexible interconnection according to the related art, with its top surface shown in perspective view. For example, the protrusions in the vertical direction are easily recognizable, which have the above-mentioned Ω shape in the z-direction. Pad mounting portions for pads or tabs can be provided in the middle of the flexible interconnection to extend longitudinally. This design is difficult to manufacture, and it is challenging to accurately position the tabs for connecting the flexible interconnection to the bus bar in a dedicated area. The waveform or Ω shape relaxes after the flexible interconnection is manufactured and is typically shipped to the pack assembly in a completely flat state. Therefore, a second manual placement is the only possible option, but this has the risk of damaging the flexible interconnection due to squeezing the flexible interconnection and scraping the sharp edges of the bus bar. Additional plastic parts have been designed and produced for the assembly process. The flexible interconnection is always in a stressed state after the welding points are fixed. Although it is desirable to allow for the automatic assembly of the flexible interconnection by using, for example, a robotic arm, such automatic assembly is not compatible with the Ω-shaped flexible interconnection.

[0016] An alternative to the Ω shape in the z-direction is a flat double S shape, as shown in, for example, Figure 3 For example, Figure 3 is a top view of a flexible interconnection according to the related art. Instead of Figure 2The Ω shape in the z direction as shown has a stress relief section that is flat and does not extend in the z direction but forms a double S shape in the plane of the flexible interconnect. However, the S shape requires an increase (e.g., doubling) in the width of the flexible interconnect, which would require twice the space in a battery module or a battery pack and result in more material being cut off (e.g., wasted) during production. More material being cut off refers to the fact that the flexible interconnect is typically formed from a single piece of material, and if the final shape of the flexible interconnect has a certain width, the raw material must be at least as wide. Thus, most of the raw material will be cut off as waste.

[0017] Another related art design includes a battery module having a bus bar, a circuit board, and connectors that connect the circuit board to the bus bar. In this related art design, all the connectors are individually mounted on the circuit board, which is in the middle on the upper side of the battery module. For example, the connectors have a buffer section with weight-reducing holes (which reduce the bending strength, compressive strength, and tensile strength), thereby allowing deformation, which has a good buffering effect. For these buffer sections, S-shaped, Ω-shaped, and Z-shaped can be used. However, all of these shapes significantly increase the width of the structure, which brings the above problems, such as increased space requirements and more material being cut off (e.g., more waste). Summary of the Invention

[0018] Embodiments of the present disclosure provide a more reliable and compact battery cell contact structure. In addition, automatic assembly is possible, and waste is reduced, thus reducing costs. This can be achieved by providing a flexible interconnect having a flat stress relief section. In addition, the width of the flexible interconnect is normal, that is, it is not significantly increased. In addition, by reducing the cut-off material, cost-effective use of materials is achieved.

[0019] The present disclosure is defined by the appended claims and their equivalents. The following description is subject to this limitation. Any disclosure outside the scope of the claims and their equivalents is for illustrative and comparative purposes.

[0020] According to an embodiment of the present disclosure, a battery module includes: a plurality of battery cells stacked along a longitudinal direction; and a flexible interconnection configured to provide electrical information of the plurality of battery cells to a battery management unit. The flexible interconnection extends in the longitudinal direction and is fixed to the plurality of battery cells. The flexible interconnection includes a stress relief section that includes a plurality of interconnection traces and extends in the longitudinal direction. The stress relief section has a cutout that extends in the longitudinal direction and separates adjacent interconnection traces among the plurality of interconnection traces from each other. The plurality of interconnection traces includes a first peripheral interconnection trace that forms a recessed portion and a second peripheral interconnection trace that is opposite to the first peripheral interconnection trace and forms a protruding portion. The height of the protruding portion in the stress relief section is the same size as the width of the flexible interconnection adjacent to the stress relief section or less than the width of the flexible interconnection adjacent to the stress relief section.

[0021] The stress relief section may be flat.

[0022] The cutout may be non-linear.

[0023] The height of the protruding portion in the stress relief section may be the same size as the width of one of the plurality of interconnection traces or less than the width of one of the plurality of interconnection traces.

[0024] The width of the flexible interconnection adjacent to the stress relief section may be equal to the width of the flexible interconnection in the stress relief section.

[0025] The flexible interconnection may further include a pad mounting portion for mounting pads, and the pads are connected to one of the battery cells. The pad mounting portion may be outside the stress relief section at an edge of the flexible interconnection extending in the longitudinal direction.

[0026] The stress relief section may be symmetric about an axis perpendicular to the longitudinal direction and passing through the center of the stress relief section.

[0027] At least two of the plurality of interconnection traces may have the same width.

[0028] The cutout may include a plurality of non-linear cutouts, and each non-linear cutout has the same width.

[0029] Each non-linear cutout may have a zigzag shape, a wavy shape, an Ω shape, a V shape, or a w shape.

[0030] The flexible interconnection may further include conductor lines.

[0031] The stress relief section may further include conductor lines.

[0032] Each interconnection trace may further include conductor lines.

[0033] The flexible interconnection may be a flexible printed circuit.

[0034] According to an embodiment of the present disclosure, a battery pack includes a plurality of battery modules described herein.

[0035] Additional aspects and features of the present disclosure can be understood from the dependent claims or the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Aspects and features of the present disclosure will become apparent to those of ordinary skill in the art by referring to the embodiments of the present disclosure described in detail with reference to the drawings, in which:

[0037] Figure 1 A schematic partial perspective view of a battery module according to the related art is shown.

[0038] Figure 2 A schematic partial perspective view of a flexible interconnection according to the related art is shown.

[0039] Figure 3 A top view of another flexible interconnection according to the related art is shown.

[0040] Figure 4 A top view of a flexible interconnection according to an embodiment of the present disclosure is shown.

[0041] Figure 5 Shows Figure 4 A top view of the flexible interconnection shown in, showing a stress relief section.

[0042] Figure 6 A top view of a stress relief section according to another embodiment of the present disclosure is shown.

[0043] Figure 7 A top view of a stress relief section according to another embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0044] Embodiments will now be described in detail with reference to the embodiments, which are illustrated in the drawings. Aspects and features of the embodiments and their implementation methods will be described with reference to the drawings. However, the present disclosure can be implemented in various different forms and should not be construed as limited to the embodiments shown herein. Rather, these embodiments are provided by way of example so that the present disclosure will be thorough and complete and will fully convey the aspects and features of the present disclosure to those skilled in the art.

[0045] It will be understood that when an element or layer is referred to as being "on", "connected to", or "coupled to" another element or layer, it can be directly on, directly connected or coupled to the other element or layer, or there can be one or more intervening elements or layers. When an element or layer is referred to as being "directly on", "directly connected to", or "directly coupled to" another element or layer, there are no intervening elements or layers. For example, when a first element is described as being "coupled" or "connected" to a second element, the first element can be directly coupled or connected to the second element, or the first element can be indirectly coupled or connected to the second element via one or more intervening elements.

[0046] In the figures, for clarity of illustration, the dimensions of various elements, layers, etc. may be exaggerated. The same reference numerals refer to the same elements. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Further, when describing embodiments of the present disclosure, the use of "may" refers to "one or more embodiments of the present disclosure". Expressions such as "at least one of..." and "any one of..." when used after a list of elements modify the entire list of elements and not individual elements in the list. For example, the expression "at least one of a, b, or c" means only a, only b, only c, both a and b, both a and c, both b and c, all of a, b, and c, or variations thereof. As used herein, the terms "use", "using...", and "used" may be considered synonymous with the terms "utilize", "utilizing...", and "utilized", respectively. As used herein, the terms "substantially", "about", and similar terms are used as approximating terms and not terms of degree, and are intended to account for the inherent variations in measured or calculated values that would be recognized by a person of ordinary skill in the art.

[0047] It will be understood that although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below can be referred to as a second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0048] For ease of description, spatial relative terms such as "below", "beneath", "under", "above", "on" etc. may be used herein to describe the relationship of one element or feature to another (other) element or feature as shown in the figures. It will be understood that the spatial relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, an element described as "below" or "beneath" another element or feature will then be oriented "above" or "over" the other element or feature. Thus, the term "below" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatial relative descriptors used herein should be interpreted accordingly.

[0049] The terminology used herein is for the purpose of describing particular embodiments of the present disclosure and is not intended to limit the present disclosure. As used herein, the singular forms "a", "an" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when used in this specification, the terms "include", "including", "comprise" and / or "comprising" specify the presence of the stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0050] The electrical connections or interconnections described herein may be provided by conductive elements (such as those on a PCB or another circuit carrier). The conductive elements may include metallization (such as surface metallization) and / or pins, and / or may include conductive polymers or ceramics.

[0051] According to an embodiment of the present disclosure, a battery module includes a plurality of battery cells and a flexible interconnection for providing electrical information of the plurality of battery cells to a battery management unit (BMU). The flexible interconnection has an elongated shape in the longitudinal direction of the battery module, which defines the longitudinal direction of the flexible interconnection. As used herein, "elongated" means having a width and a length, where the length is greater than the width, for example, the length is twice the width, ten times the width, or twenty times the width, etc. The flexible interconnection is fixed to at least one battery cell. In addition, the flexible interconnection includes at least one flat stress relief section extending along the longitudinal direction of the battery module. The at least one flat stress relief section includes at least one non-linear (e.g., curved) cut extending along the longitudinal direction of the flexible interconnection. The at least one cut refers to, for example, a longitudinal opening or hole starting from the top side and ending at the bottom side (e.g., extending completely through the thickness of the flexible interconnection). For example, the at least one cut can be a through hole. Non-linear, for example, means that two points "A" and "B" are not connected by a straight line but in an indirect way. The connection can be curved or can include edges. These points can be connected by two intersecting (e.g., crossing) lines. A plurality of interconnect traces are separated from each other by at least one non-linear cut. Two interconnect traces are formed next to each cut.

[0052] Embodiments of the present disclosure relate to a novel relaxation-expandable element formed between solid flexible interconnects by using (or including) cuts or slots. This can be achieved by forming several parallel double S-shapes (which have a smaller width compared to the normal (e.g., average) width of the flexible interconnection) to simultaneously allow relative longitudinal extension and a flat design between the solid portions of the flexible interconnection.

[0053] Therefore, a particularly compact design for the flexible interconnection is provided, which is slender (e.g., has a narrow width) and flexible in the longitudinal direction. Flexible means having the ability to be compressed and stretched. Compression can also be referred to as compressive stress. Tension or expansion can also be referred to as tensile stress. Compression and tension can occur repeatedly.

[0054] Embodiments shown in the drawings will be described in detail below.

[0055] Figure 1 A battery module 1 according to the related art is shown. Figure 1is a partial perspective view of the upper surface of the battery module 1, in which a plurality of battery cells 2 are arranged in parallel along the longitudinal direction of the battery module 1. The plurality of battery cells 2 are connected to each other by bus bars 30. The bus bars 30 connect the terminals 3 of the battery cells 2. For example, two adjacent battery cells 2 are connected by a bus bar 30. The first part of the bus bar 30 extends along the longitudinal direction of the battery cell 2, on top of the battery cell 2 and parallel to the battery cell 2, and two in the first part are connected to one bus bar 30. For example, the bus bar 30 extends in the stacking direction of the battery cells. Thus, in Figure 1 the reference numeral 30 denotes the first two bus bars. The bus bar 30 may have a flat structure. On top of the bus bar 30, pads 40 connected to the flexible interconnection 10 are arranged. The flexible interconnection 10 extends along the battery module 1 in the longitudinal direction. For example, each of the six bus bars 30 has a pad 40, and they are all connected to the same flexible interconnection 10. Thus, the flexible interconnection 10 has at least six signal lines. The number of signal lines formed on the flexible interconnection 10 is equal to the number of bus bars 30 connected to the flexible interconnection 10.

[0056] Figure 2 is a perspective view of the upper surface of the flexible interconnection of the battery cell contact structure according to the related art. For example, Figure 2 shows the flexible interconnection 10 and the FPC 12 according to the related art. The flexible interconnection 10 has mounting holes 17 on its side surface, having a margin for adjustment when the flexible interconnection 10 is placed. In the middle of the flexible interconnection 10, a pad mounting portion 19 may be provided. For example, the flexible interconnection 10 is connected to the bus bar 30 (e.g., see Figure 1 ) or the cell terminal 3 (e.g., see Figure 1 ) at the pad mounting portion 19 by pads or tabs. The signal lines for transmitting the electrical information of the battery cell 2 to the battery management system are located on the bottom of the flexible interconnection 10. For example, stress relief sections 20 are formed to extend in the vertical direction so that the flexible interconnection 10 is not flat. At least one stress relief section 20 may be located between two pad mounting portions 19.

[0057] Figure 3is a partial top view of a stress relief section 20 on an upper surface of a flexible interconnect 10 designed to be flat according to related art. The flexible interconnect 10 has a width a at the leftmost and rightmost sides, and in the stress relief section 20, a protruding portion 26 having a protruding height b and a recessed portion 25 on an edge of the flexible interconnect 10 opposite to the protruding portion 26 in the stress relief section 20. Throughout the present disclosure, the height b is defined and / or measured from an outer edge of the flexible interconnect 10 (the outer edge being parallel to a longitudinal direction in which the flexible interconnect 10 extends and located on a side of the flexible interconnect 10 in a direction same as a protruding direction of the protruding portion 26) to a tangent line that is tangent to an outer edge of the protruding portion 26 and is away from and parallel to the outer edge of the flexible interconnect 10. According to related art, the height b of the protruding portion is significant, indicating that the value of the height b of the protruding portion is at least close to the width a of the flexible interconnect 10, or much greater than the width a of the flexible interconnect 10. Accordingly, the depth c of the recessed portion 25 significantly exceeds the width a of the flexible interconnect 10. For example, a distance from an inflection point of the recessed portion 25 to an inner edge of the flexible interconnect 10 (the inner edge being parallel to a longitudinal direction in which the flexible interconnect 10 extends and located on a side of the flexible interconnect 10 in a direction opposite to the protruding direction of the protruding portion 26) exceeds the width a of the flexible interconnect. This results in an increase in a total width of the flexible interconnect 10, which is the width a plus the height b. Thus, according to Figure 3 manufacture of this flexible interconnect 10 requires a large amount of material to be cut off on left and right sides of the stress relief section 20 because the flexible interconnect 10 is typically formed monolithically in one piece.

[0058] Regarding Figures 4 to 7 reference numerals used may denote structures different from structures denoted by the same reference numerals by Figures 1 to 3 reference. Figure 4 and Figure 5 are top views showing an upper side of a flexible interconnect 10 (e.g., FPC 12) according to some embodiments of the present disclosure. Referring to Figure 4 and Figure 5 , according to some embodiments of the present disclosure, the flexible interconnect 10 may be linear and may include a stress relief section 20, which may be referred to as a stress adjustment section. The stress relief section 20 may include a structure configured to absorb stress. The structure may include a non-linear cut 23 and an interconnect trace 24, which will be described in detail below. A main section 21 of the flexible interconnect 10 may be defined at two ends (e.g., opposite ends) of the stress relief section 20. The main section 21 has a width a i , and in some embodiments, extends in a longitudinal direction of the flexible interconnect 10. The width a of the flexible interconnect 10 in the stress relief section 20 s is less than or equal to the width a of the flexible interconnect 10 in the main section 21 i . The width a of the stress relief section 20s does not include the void or depth c formed by the recessed portion 25. The stress relief section 20 is terminated by the external interconnect traces 24a and 24b (e.g., at least two external interconnect traces 24a and 24b, which will be described later). The longitudinal direction of the flexible interconnect 10 may be the same as the stacking direction of the battery cells 2, but is not limited thereto. Width a i and / or a s may be in the range from about 2 mm to about 20 mm, about 4 mm to about 15 mm, or about 6 mm to about 10 mm. For example, width a i and / or a s may depend on the number of battery cells 2 (or may be determined based on the number of battery cells 2), e.g., based on the number of busbars 30 that must be connected by the flexible interconnect 10. A width of about 2 mm may be sufficient for a small battery module. A width of about 20 mm may be sufficient for a large-scale application. Although Figure 4 the main section 21 of the flexible interconnect 10 shown in is relatively short, but the present disclosure is not limited thereto. In other embodiments, the main section 21 may span a distance longer than the stress relief section 20 and / or its multiples. The pad mounting section 22 may be adjacent to the main section 21, where the pads 40 may be mounted to the flexible interconnect 10 at the pad mounting portion 19 for connecting the flexible interconnect 10 to the busbar 30 through the pads 40. For example, the pad mounting section 22 may have a greater width than the main section 21. The pad mounting section 22 may have the same or substantially the same width as the main section 21 or the same or substantially the same width as the stress relief section 20. For example, in an embodiment where the pad mounting section 22 is directly attached to the stress relief section 20, the main section 21 may also be the portion of the flexible interconnect 10 on the side opposite the stress relief section 20 of the pad mounting section. For example, the "main section" may refer to the section of the flexible interconnect 10 where the flexible interconnect 10 extends along the longitudinal direction and has its main width without any recesses or protrusions. The flexible interconnect 10 may have a rectangular shape in the main section 21. The main width refers to the width of the flexible interconnect 10 at a section different from the pad mounting section 22 and different from the stress relief section 20. For example, more than about 80% of the flexible interconnect 10 has this main width.

[0059] In another embodiment, the stress relief section 20 may be displaced relative to an adjacent section (e.g., the main section 21 and / or the pad mounting section 22). Displacement refers to a movement or arrangement relative to the longitudinal direction of the flexible interconnect 10, and the stress relief section 20 may move away from the original longitudinal direction in the same plane as the flexible interconnect 10. For example, the stress relief section 20 may move perpendicular to the longitudinal direction of the flexible interconnect 10. However, the flexible interconnect 10 remains continuous.

[0060] Figure 5 More particularly, the stress relief section 20 is shown. In some embodiments, the stress relief section 20 may include two non-linear cuts 23 extending along the longitudinal direction of the flexible interconnect 10. The longitudinal extension of the non-linear cuts 23 may be non-linear. Non-linear means that two points are not connected by a straight line. In other words, they are connected in a circuitous manner. The non-linear cuts 23 may be curved and may have a meander shape, or may include two or more straight lines with intersections between the straight lines. A meandering riverbed is common in nature and forms a well-known shape. The shape of the stress relief section 20 may also be an Ω shape, where the legs of the Ω are partially pulled apart. Although the Ω shape is almost circular, when the lower straight portion is pulled apart, the circular shape flattens and may form Figure 4 and Figure 5The shape depicted. The non-linear cut 23 has a width e. The stress relief section 20 may have at least two non-linear cuts 23. In some embodiments, the width e of each non-linear cut 23 is the same. In another embodiment, the width e of at least two non-linear cuts 23 is the same. The width e may be constant throughout the length of the non-linear cut 23 or may vary. One non-linear cut 23 divides the flexible interconnect 10 into at least two interconnect traces 24. For example, the stress relief section 20 may have two outer interconnect traces 24a and 24b on its edges. The outer profile of the first outer interconnect trace 24a may form a recessed portion 25. The outer profile of the second outer interconnect trace 24b opposite the first outer interconnect trace 24a may form a protruding portion 26. In the illustrated embodiment, three interconnect traces 24 are formed by two non-linear cuts 23. In other words, n non-linear cuts 23 form n + 1 interconnect traces 24. The interconnect traces 24 may have a width d. For example, at least two of the interconnect traces 24 have the same width d. All of the interconnect traces 24 may have the same or substantially the same width d, or may have different widths or varying widths. For example, the outer (or peripheral) interconnect traces 24a and 24b may have the largest width and each inner interconnect trace 24c may have a smaller width. For example, the outer interconnect traces 24a and 24b may have a smaller width than each inner interconnect trace 24c. This will create flexibility towards the interconnect traces 24 with a smaller width. The width d may be in the range from about 1 mm to about 10 mm, about 2 mm to about 8 mm, or about 3 mm to about 5 mm. A width of about 1 mm provides sufficient strength and is the most flexible. At the other end of the range, a width of about 10 mm provides very good strength while still being sufficiently flexible. The symmetry axis S extends through the middle of the stress relief section 20. The flexible interconnect 10 may be symmetric about the symmetry axis S. The symmetry axis S may be an axis perpendicular to the longitudinal direction and may pass through the center (or central point) of the stress relief section 20. The non-linear cut 23 may have an S shape. Since the S shape extends in two opposite directions on both sides of the symmetry axis S, this shaped cut may be referred to as a double S-shaped cut. For example, both the non-linear cut 23 and the interconnect traces 24 may have a double S shape. For example, the shape of the non-linear cut 23 and / or the shape of the interconnect traces 24 may extend parallel to each other. Even though they may extend parallel to each other, they may have different dimensions and / or lengths, as Figure 5 shown, where the first outer non-linear cut 23a is shorter than the second outer non-linear cut 23b in the longitudinal direction of the flexible interconnect 10. In other embodiments, the non-linear cuts 23 may all or partially have the same or substantially the same length. Additionally, as Figure 4 and Figure 5As shown, the second outer non-linear cut 23b may have a linear portion that is longer than the linear portion of the first outer non-linear cut 23a near the axis of symmetry S.

[0061] Since the non-linear cut 23 extends non-linearly, the recessed portion 25 and the protruding portion 26 are formed in the flexible interconnect 10. When a force F acts on the outer end of the stress relief section 20 or the outer end of the flexible interconnect 10 in the width direction of the flexible interconnect 10 (see, for example, Figure 4 the longitudinal arrow in), this tension can cause deformation of the stress relief section 20. This means that the force F can cause intentional (or intended) deformation of the stress relief section 20. For example, stress can be concentrated in the stress relief section 20, and deformation of other parts of the flexible interconnect 10 in an uncontrolled manner can be prevented or significantly reduced. For example, in a case where compressive stress is generated that may be caused by the movement m1 at both ends of the stress relief section 20, one or more interconnect traces 24 may be deformed, for example, by a reactive movement rm1, and the longitudinal ends of the stress relief section 20 may move towards each other in the longitudinal direction of the flexible interconnect 10. Thus, the stress relief section 20 is compressed, and the height b of the protruding portion 26 can increase. For example, in a case where tensile stress is generated that may be caused by the movement m2, the interconnect traces 24 may be deformed, for example, by a reactive movement rm2, and the longitudinal ends of the stress relief section 20 move away from each other. Thus, the stress relief section 20 flattens, that is, the height b of the protruding portion 26 can become smaller. In the previous examples, all deformations occur in the same plane as the plane in which the flexible interconnect 10 extends. Therefore, the deformation of the flexible interconnect 10 in the vertical direction (for example, a direction perpendicular to the longitudinal direction of the flexible interconnect 10 and perpendicular to the width of the flexible interconnect 10) is minimal or zero. According to Figure 5 the embodiment shown in, the recessed portion 25 may be formed adjacent to the first outer interconnect trace 24a. In some embodiments, the recessed portion 25 may have a rounded shape, such as circular or oval. The recessed portion 25 has a depth c. The depth c may be less than the width a of the flexible interconnect i . For example, the width c may be in the range from about a i / 2 to the width d of the interconnect trace 24. The protruding portion 26 may be formed on the opposite side of the recessed portion 25 (for example, the opposite side in a direction perpendicular to the extending direction of the flexible interconnect 10). The protruding portion 26 has a height b. In one embodiment, the height b and the depth c may be the same or substantially the same. The recessed portion 25 and the protruding portion 26 refer to parts of the flexible interconnect 10 and define the outer shape of the flexible interconnect 10. According to some embodiments of the present disclosure, the height b of the protruding portion 26 is equal to or less than the width a of the flexible interconnect 10 adjacent to the stress relief section 20 iAccording to some embodiments of the present disclosure, the width a of the flexible interconnect 10 in the stress relief section 20 S may be not greater than or equal to the width a of the flexible interconnect 10 in the main section 21 i The width a of the flexible interconnect 10 in the stress relief section 20 S can be measured by the tangent of the non-linear outer edge of the first external interconnect trace 24a (the tangent is parallel to the longitudinal direction in which the flexible interconnect 10 extends and away from the non-linear cut 23) to the tangent of the opposite outer edge of the second external interconnect trace 24b (the tangent is parallel to the longitudinal direction in which the flexible interconnect 10 extends and away from the non-linear cut 23). In the stress relief section 20, when taking the outer edge of the flexible interconnect 10 on the side of the recessed portion 25 as the baseline, the total width of the flexible interconnect 10 in the stress relief section 20 is the width a i plus the height b, where the width a i refers to the width of the flexible interconnect 10 in the main section 21 (also referred to as the main width), and the height b refers to the width of the protruding portion 26 (which exceeds the flexible interconnect 10 in the main section 21). In other words, the total width of the flexible interconnect 10 is the width a i plus the height b. In some embodiments, the height b of the protruding portion 26 may be equal to the width d of the interconnect trace 24. In some embodiments, the height b of the protruding portion 26 may be less than the width d of the interconnect trace 24. For example, the height b of the protruding portion 26 in the stress relief section 20 may be not greater than the width d of one interconnect trace 24. The smaller the height b of the protruding portion 26, the more compact the flexible interconnect 10 will be. For example, the smaller the height b of the protruding portion 26, the less amount of material to be cut off. On the other hand, the recessed portion 25 does not directly affect the height b of the protruding portion 26, but only defines the depth c. Therefore, in some embodiments, if the height b of the protruding portion 26 is less than the depth c, the width a of the flexible interconnect 10 in the stress relief section 20 s can be less than the width a of the flexible interconnect 10 i . For example, if the width a of the stress relief section 20 s is sufficient to accommodate all the signal lines, the width a of the stress relief section 20 S can be less than the width a of the flexible interconnect 10 i .

[0062] Figure 6 Shows another flexible interconnect 10 according to some embodiments of the present disclosure. For example, Figure 6 is a top view of the stress relief section 20, similar to Figure 5As shown in. In this embodiment, the stress relief section 20 has a V shape. The V shape may have a corner 28 on the axis of symmetry S. For example, the non-linear cut 23 and the interconnecting trace 24 may have a corner 28. The corner 28 may be sharp or rounded, etc. The corner 28 in the recessed portion 25 may be referred to as the inner corner 28a. Similarly, the corner 28 in the protruding portion 26 may be referred to as the outer corner 28b. In addition, the definitions of the stress relief section 20, the main section 21, and the pad mounting section 22 for the above-described embodiment apply. For example, the definition of the height b of the protruding portion 26 applies accordingly. Although in Figure 6 In the embodiment shown, the second external interconnecting trace 24b forming the protruding portion 26 has a sharp tip 27 or a corner 28, but the tip 27 or the corner 28 may be cut off or rounded. Therefore, the height b of the protruding portion 26 can be reduced.

[0063] Figure 7 is another embodiment of the present disclosure similar to the embodiment in Figure 6 FIG. []. In this embodiment, the stress relief section 20 has a W shape. As described above, the W shape may be formed by two V shapes. In such an embodiment, the axis of symmetry S extends along the middle of the W shape. The W shape may have two protruding portions 26 on the lower side of the W shape. In some embodiments, the W shape may have an additional protruding portion 26 on the upper side of the middle of the W shape. In such an embodiment, there may be a total of three protruding portions 26. In some embodiments, the non-linear cut 23 may not be continuous throughout the stress relief section 20, but may be discontinuous. In some embodiments, the non-linear cut 23 may be continuous, even in a longer shape, such as continuous throughout the W shape.

[0064] Note that, for improved readability, some of the features indicated by the above markings are omitted in other parts of the drawings. However, it will be clear to those skilled in the art that the cut-off corners can be applied to all other corners of the present disclosure. In addition, it should be remembered that many other shapes can be used. For example, the stress relief section 20 is not limited to the shape described with respect to Figures 5 to 7 For example, other shapes having an axis of symmetry, or even shapes without an axis of symmetry, can be used. For example, simple basic shapes or any concatenation of the shapes disclosed herein are suitable.

[0065] When comparing the embodiments shown in Figures 5 to 7 the following differences become apparent. In the embodiment shown in Figure 5 the stress relief section 20 including the non-linear cut 23 and / or the interconnecting trace 24 has a rounded shape, while in Figure 6 and Figure 7In the embodiment shown, the stress relief section 20 has a straight (or edged) shape. A rounded shape can distribute longitudinal stress in a more dispersed manner. Figure 7 and Figure 6 The straight (or edged) shape in the embodiment shown has a linear part and a corner part, which can be easier to manufacture. Compare Figure 6 and Figure 7 In the embodiment shown, the V shape is more compact. On the other hand, the w shape has the ability to vertically move the protruding part 26 in the middle. Therefore, the deformation characteristics of the stress relief section 20 can be adjusted. In addition, in all embodiments, the length of the non-linear cut can be changed.

[0066] For all embodiments of the present disclosure (including the above embodiments), the conductor line can pass through the flexible interconnect 10 in the longitudinal direction. For example, the flexible interconnect 10 can include at least one conductor line. One conductor line connects one pad 40 (see, for example Figure 4 ) to the other end of the flexible interconnect 10 (where the BMU / BMS can be located). When the flexible interconnect 10 includes multiple conductor lines, the conductor lines can be distributed between the interconnect traces 24. For example, in each stress relief section 20, each interconnect trace 24 can include at least one conductor line. For example, one interconnect trace 24 can include multiple conductor lines. In such an embodiment, when defining the width d of each interconnect trace 24, the distance between the conductor lines is considered. Similarly, when defining the width e of the non-linear cut 23, the degree of deformation of the interconnect traces 24 in the stress relief section 20 should be considered so that the interconnect traces 24 do not contact each other. In some embodiments, the interconnect traces 24 can contact, but the flexible interconnect 10 can be designed such that the conductor lines do not get too close to each other, for example, do not contact each other. In addition, it is clear to those skilled in the art that all measurements involved in the present disclosure are measured in a relaxed state (that is, a state without stress).

[0067] Some reference numerals

[0068] 1 Battery module

[0069] 2 Battery cell

[0070] 3 Terminal

[0071] 10 Flexible interconnect

[0072] 12 Flexible printed circuit

[0073] 17 Mounting hole

[0074] 19 Pad mounting part

[0075] 20 Stress relief section

[0076] 21 Main section

[0077] 22 Pad mounting section

[0078] 23 Nonlinear notch

[0079] 24 Interconnecting trace

[0080] 25 Recessed portion

[0081] 26 Protruding portion

[0082] 27 Tip

[0083] 28 Corner

[0084] 28a Outer corner

[0085] 28b Inner corner

[0086] 30 Bus bar

[0087] 40 Pad

Claims

1. A battery module, comprising: A plurality of battery cells are stacked along the longitudinal direction; as well as A flexible interconnection configured to provide electrical information of the plurality of battery cells to a battery management unit, the flexible interconnection extending in the longitudinal direction and fixed to the plurality of battery cells, the flexible interconnection comprising: a stress relief section extending in the longitudinal direction and comprising a plurality of interconnect traces, wherein the stress relief section has a cutout extending along the longitudinal direction, the cutout separating adjacent interconnect traces of the plurality of interconnect traces from each other, wherein the plurality of interconnect traces include a first peripheral interconnect trace forming a concave portion and a second peripheral interconnect trace opposite to the first peripheral interconnect trace and forming a convex portion, and Wherein a height of the protrusion in the stress relief section is equal to or less than a width of the flexible interconnection adjacent to the stress relief section. 2 . The battery module of claim 1 , wherein the stress relief section is flat. The battery module according to claim 2 , wherein the cutout is non-linear. 4 . The battery module of claim 3 , wherein the height of the protruding portion in the stress relief section is equal to or less than a width of one of the plurality of interconnect traces. 5 . The battery module of claim 1 , wherein the width of the flexible interconnect adjacent to the stress relief section is equal to the width of the flexible interconnect in the stress relief section.

6. The battery module according to claim 2, wherein the flexible interconnect further comprises a pad mounting portion for mounting a pad connected to one of the battery cells, wherein the pad mounting portion is outside the stress relief section at an edge of the flexible interconnect extending along the longitudinal direction. 7 . The battery module of claim 1 , wherein the stress relief section is symmetrical about an axis perpendicular to the longitudinal direction and passing through a center of the stress relief section.

8. The battery module of claim 1, wherein at least two of the plurality of interconnect traces have the same width. 9 . The battery module according to claim 1 , wherein the cutout comprises a plurality of non-linear cutouts, each of the non-linear cutouts having a same width. 10 . The battery module according to claim 9 , wherein each of the nonlinear cutouts has a zigzag shape, a wavy shape, an Ω shape, a V shape, or a W shape.

11. The battery module of claim 1, wherein the flexible interconnect further comprises a conductor line.

12. The battery module of claim 1, wherein the stress relief section further comprises a conductor line.

13. The battery module of claim 1, wherein each of the interconnect traces further comprises a conductor line.

14. The battery module of claim 1, wherein the flexible interconnect is a flexible printed circuit.

15. A battery pack comprising a plurality of battery modules according to any one of claims 1 to 14.

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