Patent Publication Number: US-2022238934-A1

Title: Battery Module and Battery Pack Including the Same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/KR2020/009286 filed on Jul. 15, 2020, which claims priority from Korean Patent Application No. 10-2019-0145144 filed on Nov. 13, 2019, the disclosures of which are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a battery module and a battery pack including the same, and more particularly to a battery module having a heating member, and a battery pack including the same. 
     BACKGROUND ART 
     Secondary batteries have attracted much attention as an energy source in various products such as mobile devices and electric vehicles. The secondary battery is a potent energy resource that can replace the use of existing products using fossil fuels, and is in the spotlight as an environmentally-friendly energy source because it does not generate by-products due to energy use. 
     Recently, along with a continuous rise of the necessity for a large-capacity secondary battery structure, including the utilization of the secondary battery as an energy storage source, there is a growing demand for a battery pack of a multi-module structure which is an assembly of battery modules in which a plurality of secondary batteries are connected in series/parallel. 
     Meanwhile, when a plurality of battery cells are connected in series/parallel to configure a battery pack, it is common to configure a battery module composed of at least one battery cell first, and then configure a battery pack by using at least one of the battery modules and adding other components. 
     Such a battery module includes a battery cell stack in which a plurality of battery cells are stacked, a busbar frame formed at each of both ends of the battery cell stack, and a sensing assembly that is located on the battery cell stack and measures the voltage and temperature of the battery cells. 
       FIG. 1  is an exploded perspective view of a conventional battery module  10 . Some configurations are omitted for convenience of description. 
     Referring to  FIG. 1 , the conventional battery module  10  may include a battery cell stack  20  in which a plurality of battery cells  21  are stacked, a busbar frame  30  formed at each of both ends (x-axis direction and opposite direction thereof) of the battery cell stack  20 , and a sensing assembly  40  that is located on the battery cell stack  20  and measures the voltage and temperature of the battery cells  21 . 
     The sensing assembly  40  may be formed of a flexible printed circuit (FPC) or a flexible flat cable (FFC). 
     Further, by installing a cover plate  50  on the upper end of the sensing assembly  40 , an attempt was made to prevent damage to the sensing assembly  40  that may occur when housed in a mono frame (not shown). 
     Meanwhile, the battery cell  21 , that is, a secondary battery, includes, for example, a nickel-cadmium battery, a nickel-hydrogen battery, a nickel-zinc battery, a lithium secondary battery, and the like. Among these, lithium secondary batteries are widely used in the field of advanced electronic devices because they have advantages over nickel-based secondary batteries, in that the memory effect hardly occurs and so charging and discharging are free, the self-discharge rate is very low, the operating voltage is high, and the energy density per unit weight is high. 
     However, the lithium secondary batteries have characteristics such that, due to the increase in resistance at low temperatures, charging and discharging are not performed smoothly, and the output and charging speed rapidly decrease. Consequently, the lithium secondary battery used in an electric driving device has a problem in that the efficiency and output of the secondary battery rapidly decreases when exposed to an external environment at a low temperature for a long time. 
     Further, as shown in  FIG. 1 , since a large number of battery cells  21  are compactly stacked to form a battery module  10 , the battery cells  21  located at the outermost side are more affected by the external environment. The battery cells  21  located at the outermost side may have a relatively low temperature, which may deepen the temperature deviation between the battery cells  21  of the battery cell stack  20 . The temperature non-uniformity between the battery cells  21  may cause a reduction in the life of the battery module  10  itself. 
     Therefore, efforts have been made to raise the temperature of the secondary battery in a low-temperature environment and reduce the temperature deviation between battery cells. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Technical Problem 
     Embodiments of the present disclosure have been designed to solve the above-mentioned problems involved in the prior art methods and, therefore, it is an object of the present disclosure to quickly escape from the low temperature region by raising the temperature of the battery cells, and to minimize the temperature deviation between the battery cells by applying more heat to the battery cell located at the outermost side. However, the problem to be solved by embodiments of the present disclosure is not limited to the above-described problems, and can be variously expanded within the scope of the technical idea included in the present disclosure. 
     Technical Solution 
     A battery module according to an embodiment of the present disclosure includes: a battery cell stack in which a plurality of battery cells are stacked; and a sensing assembly located on the battery cell stack, wherein the sensing assembly includes a main body located on the battery cell stack and a module connector connected to the main body, wherein the main body is a flexible printed circuit (FPC) or a flexible flat cable (FFC), and wherein the main body includes a heating wire circuit. 
     The main body may cover the entire upper surface of the battery cell stack. 
     The heating wire circuit may pass through an upper part of each of the plurality of battery cells. 
     The plurality of battery cells may be stacked along a direction parallel to the main body while standing vertically upright to the main body. 
     The interval between the heating wire circuits passing through the upper part of the battery cells located at the outermost side of the battery cell stack may be narrower than the interval between the heating wire circuits passing through the upper part of the other battery cells. 
     The heating wire circuit is configured in which a length of the portion passing through an upper part of the battery cell located at the outermost side of the battery cell stack may be longer than the length of the portion passing through an upper part of the other battery cell. 
     The interval between the heating wire circuits may become narrower as it is directed outward from the center of the battery cell stack. 
     The module connector may include a heating wire circuit input pin and a heating wire circuit output pin each connected to the heating wire circuit. 
     The main body may further include a voltage sensing circuit and a temperature sensing circuit. 
     The battery module may further include a thermal conductive resin layer located on a lower surface of the battery cell stack. 
     The battery module may further include a module frame that houses the battery cell stack, wherein the main body may be located between the upper surface of the battery cell stack and the module frame. 
     Advantageous Effects 
     According to the embodiments of the present disclosure, the temperature of the battery cells contained in the battery module can be effectively raised by using the heating wire circuit contained in the sensing assembly. 
     Further, more heat can be applied to the battery cell in which the heating wire circuit is located on the outermost side, and thus, the temperature deviation between battery cells can be minimized. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a conventional battery module. 
         FIG. 2  is a perspective view of a battery module according to one embodiment of the present disclosure. 
         FIG. 3  is an exploded perspective view of the battery module of  FIG. 2 . 
         FIG. 4  is a perspective view showing a sensing assembly contained in the battery module of  FIG. 3 . 
         FIG. 5  is a plan view of the sensing assembly of  FIG. 4  as viewed from above. 
         FIG. 6  is a cross-sectional view of the battery module of  FIG. 2  taken along the cutting line A-A′. 
         FIG. 7  is a plan view of a sensing assembly according to a modified embodiment of the present disclosure as viewed from above. 
         FIG. 8  is a schematic diagram showing a battery cell, a heating wire circuit, a voltage sensing circuit, and a temperature sensing circuit. 
         FIG. 9  is a view showing a U-shaped frame and an upper plate. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. The present disclosure may be modified in various different ways, and is not limited to the embodiments set forth herein. 
     Portions that are irrelevant to the description will be omitted to clearly describe the present disclosure, and like reference numerals designate like elements throughout the specification. 
     Further, in the figures, the size and thickness of each element are arbitrarily illustrated for convenience of description, and the present disclosure is not necessarily limited to those illustrated in the figures. In the figures, the thickness of layers, regions, etc. are exaggerated for clarity. In the figures, for convenience of description, the thicknesses of some layers and regions are shown to be exaggerated. 
     In addition, it will be understood that when an element such as a layer, film, region, or plate is referred to as being “on” or “above” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, it means that other intervening elements are not present. Further, the word “on” or “above” means disposed on or below a reference portion, and does not necessarily mean being disposed on the upper end of the reference portion toward the opposite direction of gravity. 
     Further, throughout the specification, when a portion is referred to as “including” a certain component, it means that it can further include other components, without excluding the other components, unless otherwise stated. 
     Further, throughout the specification, when referred to as “planar”, it means when a target portion is viewed from the upper side, and when referred to as “cross-sectional”, it means when a target portion is viewed from the side of a cross section cut vertically. 
       FIG. 2  is a perspective view of a battery module  100  according to one embodiment of the present disclosure,  FIG. 3  is an exploded perspective view of the battery module  100  of  FIG. 2 , and  FIG. 4  is a perspective view showing a sensing assembly  400  contained in the battery module  100  of  FIG. 3 . 
     Referring to  FIGS. 2 to 4 , the battery module  100  according to the present embodiment includes: a battery cell stack  200  in which a plurality of battery cells  210  are stacked; and a sensing assembly  400  located on the battery cell stack  200 , wherein the sensing assembly  400  includes a main body  410  located on the battery cell stack  200  and a module connector  440  connected to the main body  410 . 
     The main body  410  is a flexible printed circuit (FPC) or a flexible flat cable (FFC), and includes a heating wire circuit described later. 
     The main body  410  is a flexible printed circuit or a flexible flat cable, which attempts to detect a phenomenon such as overvoltage, overcurrent, and overheating of each battery cell  210  by sensing the voltage and temperature of the plurality of battery cells  210 , and transmits electrical information to the BMS (Battery Management System) via the module connector  440 . Thus, the main body  410  may include a voltage sensing circuit and a temperature sensing circuit. 
     Meanwhile, a first busbar frame  310  and a second busbar frame  320  may be formed on the front surface (x-axis direction) and the rear surface (direction opposite to the x-axis) of the battery cell stack  200 , respectively. Respective busbar frames  310  and  320  are equipped with a busbar  300 , and electrode leads of the battery cells  210  are connected to the busbar  300 , so that the battery cells  210  may be electrically connected to each other. More specifically, after the electrode leads of the battery cells  210  pass through the slits formed in each of the busbar frames  310  and  320 , they can be curved and joined to the busbar  300 . 
     The battery cell stack  200  may be housed in a mono frame  600  having an opened front surface (x-axis direction) and an opened rear surface (direction opposite to the x-axis), and an end plate  700  may cover the opened front surface and the opened rear surface. The connection between the mono frame  600  and the end plate  700  is not particularly limited, but they may be weld-joined to each other. 
     Meanwhile, when the sensing assembly  400  and the battery cell stack  200  are housed in the mono frame  600 , a cover plate  500  can be disposed on a sensing assembly  400  to prevent damage to the sensing assembly  400 . 
       FIG. 5  is a plan view of the sensing assembly  400  of  FIG. 4  as viewed from above, and  FIG. 6  is a cross-sectional view of the battery module  100  of  FIG. 2  taken along the cutting line A-A′. 
     Referring to  FIGS. 5 and 6 , the main body  410  including a heating wire circuit  411  may cover the entire upper surface of the battery cell stack  200 . Moreover, the heating wire circuit  411  may pass through the upper part of each of the plurality of battery cells constituting the battery cell stack  200 . The heating wire circuit  411  may be a heating wire utilizing electric resistance. 
     When the temperature of the battery cells becomes low, there is a problem that the resistance increases and thus, charging and discharging are not performed smoothly, and the output and charging speed rapidly decrease. Therefore, in the present embodiment, the temperature of the battery cell stack  200  may be artificially raised based on the applied electric signal by containing the heating wire circuit  411  in the sensing assembly  400 . 
     As shown in  FIG. 6 , the heating wire circuit  411  is contained inside the sensing assembly  400  located at the upper part of the battery cell stack  200 , and the upper space of the battery cell stack  200  is generally a space in which a sensing assembly can be located, which utilizes the existing space. In other words, due to the insertion of a separate heating member, it utilizes the space in the width (y-axis direction) direction of the sensing assembly  400  rather than requiring additional space, and therefore, it can be considered as utilizing the existing internal space efficiently. The width (y-axis direction) of the sensing assembly  400  is extended so as to cover the entire upper surface of the battery cell stack  200 , so that a method for heating the battery cell stack  20  can be provided without an increase in the height (z-axis direction) of the battery module. 
     In addition to the space utilization aspects, the existing sensing assembly is utilized, so that additional costs and manufacturing processes can be minimized. 
     Further, since the heating wire circuit  411  is located inside the battery module, the heat transfer coefficient to the battery cells is relatively good as compared with the case where a separate heating member is disposed outside the battery module. Further, it can be protected from the rigid mono frame  600 , and thus can be safe from vibration, shock and the like even without an additional protection member. 
     Meanwhile, a plurality of battery cells can be stacked along the direction parallel to the main body  410  (y-axis direction) while standing vertically upright to the main body  410  to form the battery cell stack  200 . Therefore, the main body  410  can come into contact with each of the battery cells, and the heating wire circuit  411  can pass through the entire upper parts of respective battery cells, so that uniform heat transfer to the battery cells is possible. 
     If the heating member is located on both sides of the battery cell stack  200 , heat is intensively transferred only to the outermost battery cells  211 , so that an overall temperature rise of the battery cell stack  200  cannot be achieved. Further, the respective battery cells may cause a swelling phenomenon that swells mainly in the y-axis direction. This swelling phenomenon is caused by an electrode becoming thicker or a gas generated from the decomposition of an internal electrolyte during the repeated charge/discharge processes. When the heating member is located on both sides of the battery cell stack  200 , the function of the heating member may be reduced or damaged due to a strong compression of the swelling. In particular, when the heating member is a heating wire circuit  411  of the heating wire using electric resistance as in the present disclosure, a short circuit or a fire may occur due to insulation breakdown caused by damage to the covering layer. 
     Meanwhile, referring to  FIGS. 3 and 6 , the battery module  100  according to the present embodiment may further include a thermal conductive resin layer  800  located on a lower surface of the battery cell stack  200 . Further, when one or more battery modules  100  configures a battery pack, a heat sink may be located at a lower end of the battery module  100 . 
     The thermal conductive resin layer  800  may include a thermal conductive resin, and in particular, may include a thermal conductive adhesive material. For example, it may include at least one of a silicone-based material, a urethane-based material, and an acrylic-based material, and in particular, it is preferable to include a urethane-based material. 
     The thermal conductive resin is a material having excellent thermal conductivity, and the heat generated in the battery cells may be discharged to the outside through the thermal conductive resin layer  800  and the heat sink. The thermal conductive resin layer  800  can be seen as a kind of cooling device. However, the thermal conductive resin includes a thermal conductive adhesive material, and is a liquid when coating, but may be a material that solidifies after the battery cell stack  200  is stacked thereon. Therefore, the thermal conductive resin layer  800  may fix the battery cell stack  200  in the battery module  100 . That is, the thermal conductive resin layer  800  in the present embodiment not only improves heat dissipation characteristics for the battery cell stack  200 , but also has an effect of effectively fixing the battery cell stack  200 . 
     In the present embodiment, the sensing assembly  400  containing the heating wire circuit  411  may be located opposite to the thermal conductive resin layer  800 , with the battery cell stack  200  being interposed therebetween. Since the sensing assembly  400  and the thermal conductive resin layer  800  are separated from each other at a certain distance, it is possible to prevent the problem that the heat transferred through the heating wire circuit  411  is not transferred to the battery cells, but is discharged to the outside through the thermal conductive resin layer  800  and the heat sink. That is, the heat wire circuit  411  according to the present disclosure can minimize a heat loss due to a cooling system member such as the thermal conductive resin layer  800 . Depending on the external temperature environment of the battery module, the heating wire circuit  411  and the thermal conductive resin layer  800  can effectively perform their respective heating and cooling functions without interfering from each other. 
     Hereinafter, a modified embodiment of the present disclosure will be described with reference to  FIG. 7 . 
       FIG. 7  is a plan view of a sensing assembly  400   a  according to a modified embodiment of the present disclosure as viewed from above. 
     Referring to  FIG. 7  together with  FIGS. 3 and 6 , the battery cell  211  located on the outermost side among the battery cells comes into contact with the sidewall of the mono frame  600 , and thus is more affected by the external environment than the battery cell  212  located on the inner side. Therefore, when exposed to a low temperature environment, the temperature of the battery cells  211  located at the outermost side becomes the lowest, which induces a temperature deviation between the battery cells. When the temperature deviation between the battery cells  210  is deepened, it may be the cause of lowering the life of the battery module  100  itself. 
     Therefore, according to the present embodiment, the interval B between the heating wire circuits  411   a  passing through the upper part of the battery cells  211  located at the outermost side of the battery cell stack  200  may be narrower than the interval C between the heating wire circuits  411   b  passing through the upper part of the other battery cells  212 . 
     Due to the difference in the interval as described above, the heating wire circuit  411  is configured in which the length of the portion passing through the upper part of the battery cell  211  located on the outermost side of the battery cell stack  200  may be longer than the length of the portion passing through the upper part of the other battery cells  212 . 
     In addition, in order to form a continuous heating gradient, the interval between the heating wire circuits  411  may be narrowed toward the outside from the center of the battery cell stack  200 . 
     This is for eliminating the temperature deviation between the battery cells  210  described above, the interval and length of the heating wire circuit  411  can be adjusted differently for each portion to transfer more heat to the battery cell  211  located at the outermost side. The heating wire circuit  411  in the present disclosure can pass through the upper part of each battery cell  210  and transfer heat to all of the battery cells  210 , and additionally, eliminate the temperature deviation between the battery cells  210  and thus contribute to the improvement of the uniform performance and life of the battery module. 
       FIG. 8  is a schematic diagram showing a battery cell, a heating wire circuit  411 , a voltage sensing circuit  412 , and a temperature sensing circuit  413 . 
     Referring to  FIG. 8 , in the embodiment of the present disclosure, a plurality of battery cells are provided. For convenience of explanation, four battery cells  210   a,    210   b,    210   c,  and  210   d  are shown. The four battery cells  210   a,    210   b,    210   c,  and  210   d  are connected in series, but this is an exemplary connection method between battery cells, and a parallel connection or a series/parallel connection is also possible. 
     As described above, a heating wire circuit  411  passing through each upper part of the battery cells  210   a,    210   b,    210   c,  and  210   d  may be provided. Moreover, the interval between the heating wire circuits  411  passing through the upper part of the battery cells  210   a  and  210   d  located on the outermost side may be narrower than the interval between the heating wire circuits  411  passing through the upper part of the other battery cells  210   b  and  210   c.    
     Further, the heating wire circuit  411  is configured in which the length of the portion passing through the upper part of the battery cells  210   a  and  210   d  located on the outermost side may be longer than the length of the portion passing through the upper part of the other battery cells  210   b  and  210   c.    
     Further, as described above, the sensing assembly of the present disclosure includes a module connector  440  connected to the main body of the sensing assembly. 
     The module connector  440  may include a heating wire circuit input pin and a heating wire circuit output pin each connected to the heating wire circuit  411 . An external electrical signal can be applied through the heat wire circuit input pin and the heat wire circuit output pin to heat the heat wire circuit  411 . However,  FIG. 8  shows, for example, an input pin and an output pin for one heating wire circuit  411 , and each time a line of the heating wire circuit  411  is added one by one, an input pin and an output pin corresponding thereto may be included in the module connector  440 . 
     Meanwhile, the main body according to the present embodiment may further include a voltage sensing circuit  412  and a temperature sensing circuit  413  in addition to the heating wire circuit  411 . As described above, since the heating wire circuit  411  is added to the sensing assembly that senses the voltage and temperature of the battery cells, the main body of the sensing assembly may further include a voltage sensing circuit  412  and a temperature sensing circuit  413 , in addition to the heating wire circuit. 
     The voltage sensing circuit  412  is connected to the voltage sensing unit  420  in contact with the electrode terminals of the respective battery cells  210   a,    210   b,    210   c,  and  210   d,  so that the voltage measurement values of the battery cells  210   a,    210   b,    210   c  and  210   d  can be transmitted as electrical information to BMS (battery management system) via a module connector  440 . 
     The temperature sensing circuit  413  is connected to a thermistor  430  located between respective battery cells  210   a,    210   b,    210   c,  and  210   d,  so that the temperature values of the battery cells  210   a,    210   b,    210   c,  and  210   d  can be transmitted as electrical information to BMS (battery management system) via the module connector  440 . 
     The voltage sensing circuit  412  and the temperature sensing circuit  413  may be connected to a voltage sensing pin and a temperature sensing pin of the module connector  440 , respectively. 
     That is, the sensing assembly in the present disclosure includes a heating wire circuit  411 , a voltage sensing circuit  412 , and a temperature sensing circuit  413 , and it can not only measure the voltage and temperature of the battery cell, but also perform the heating function without any additional member. 
     Meanwhile, since the sensing assembly in the present disclosure includes a flexible printed circuit (FPC) or a flexible flat cable (FFC), the heating wire circuit  411 , the voltage sensing circuit  412 , and the temperature sensing circuit  413  are inserted inside the cable, and it is easy to cope with external shock. That is, although the heating wire circuit  411  is illustrated in  FIG. 5  or  FIG. 7  for convenience of description, it may be a shape of being inserted into a cable. 
     Meanwhile, the battery module according to the present embodiments may include a module frame for housing the battery cell stack, and the main body of the sensing assembly may be located between the upper surface of the battery cell stack and the module frame. 
     The module frame may be a mono frame  600  as shown in  FIG. 3 , or a U-shaped frame described with reference to  FIG. 9  below. 
     Once again referring to  FIG. 3 , the mono frame  600  may be a metal frame having an opened front surface (x-axis direction) and an opened rear surface (direction opposite to the x-axis). The battery cell stack  200  is housed through the opened front surface or the opened rear surface, and a cover plate  500  may be disposed to protect the sensing assembly  400  during the housing process. 
       FIG. 9  is a view showing a U-shaped frame  610  and an upper plate  620 . 
     Referring to  FIG. 9 , the module frame may include a U-shaped frame  610  and an upper plate  620 . 
     The U-shaped frame  610  may have a structure in which the front surface (x-axis direction), the rear surface (direction opposite to the x-axis) and the upper surface (z-axis direction) are opened, and it is provided with the bottom part  611  and both side parts  612  extending in the upper direction (Z-axis direction) from opposite ends of the bottom part  611 . 
     The upper plate  620  is connected to the opened upper surface of the U-shaped frame  610 , and the opened front and rear surfaces of the U-shaped frame  610  may be respectively connected to the end plate  700  in  FIG. 3 . The U-shaped frame  610  may be joined to the upper plate  620  by welding. It is preferable that the U-shaped frame  610  and the upper plate  620  are metal plates having a predetermined strength. 
     A thermal conductive resin can be coated onto the bottom part  611  of the U-shaped frame  610  to form a thermal conductive resin layer, and then the battery cell stack and the sensing assembly may be housed thereon. Next, the upper plate  620  may be joined to the opened upper surface of the U-shaped frame  610 . By the assembly procedure as described above, the U-shaped frame  610  can eliminate the cover plate  500  as shown in  FIG. 3 . 
     One or more battery modules according to the present embodiment described above may be mounted together with various control and protection systems such as a battery management system (BMS) and a cooling system to form a battery pack. 
     The battery module or the battery pack including the battery module may be applied to various devices. These devices may be applied to transportation means such as an electric bicycle, an electric vehicle, a hybrid vehicle, but the present disclosure is not limited thereto and can be applied to various devices that can use the secondary battery. 
     Although the preferred embodiments of the present disclosure have been described in detail above, the scope of the present disclosure is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present disclosure defined in the following claims also belong to the scope of rights. 
     DESCRIPTION OF REFERENCE NUMERALS 
       100 : battery module 
       200 : battery cell stack 
       210 : battery cell 
       300 : busbar 
       310 : first busbar frame 
       320 : second busbar frame 
       400 : sensing assembly 
       410 : main body 
       411 : heating wire circuit 
       420 : voltage sensing unit 
       430 : thermistor 
       440 : modular connector