Patent Publication Number: US-2023145109-A1

Title: Battery module and battery pack including the same

Description:
TECHNICAL FIELD 
     This application is a US national phase of international application No. PCT/KR2021/014280 filed Oct. 14, 2021, and claims the benefit of priority based on Korean Patent Application No. 10-2020-0133763 filed Oct. 15, 2020, the contents of which are incorporated as if fully set forth herein. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a battery module and a battery pack including the same, and more particularly, to a battery module which is capable of simultaneously improving safety and maintaining rigidity of a battery module, and a battery pack including the same. 
     BACKGROUND 
     In modern society, as the use of portable devices, such as mobile phones, notebook computers, camcorders, and digital cameras, has become commonplace, the development of technologies related to the mobile devices has become active. Further, a rechargeable secondary battery is a measure to solve the air pollution of existing gasoline vehicles that use fossil fuels, and is used as a power source for an Electric Vehicle (EV), a Hybrid Electric Vehicle (HEV), a Plug-in Hybrid Electric Vehicle (P-HEV), and the like, so that the need for development of the secondary battery is increasing. 
     Currently commercialized secondary batteries include nickel cadmium batteries, nickel hydride batteries, nickel zinc batteries, lithium secondary batteries, and the like, and among them, the lithium secondary battery is in the spotlight for its advantages in that charge and discharge are free because of minimal memory effect, a self-discharge rate is very low, and energy density is very high, compared to the nickel-based secondary battery. 
     The lithium secondary battery mainly uses a lithium-based oxide and a carbon material as a positive electrode active material and a negative electrode active material, respectively. The lithium secondary battery includes an electrode assembly in which a positive electrode plate and a negative electrode plate, to which the positive electrode active material and the negative electrode active material are applied, respectively, are disposed with a separator interposed therebetween, and an exterior material, that is, a battery case, that seals and accommodates the electrode assembly together with an electrolyte. 
     In general, the lithium secondary battery may be classified into a can-type secondary battery in which the electrode assembly is embedded in a metal can, and a pouch-type secondary battery in which the electrode assembly is embedded in a pouch of an aluminum laminate sheet, according to a shape of the exterior material. 
     In the case of the secondary batteries used in small devices, two or three battery cells are disposed, but in the case of the secondary batteries used in medium and large devices, such as automobiles, a battery module in which the plurality of battery cells are electrically connected is used. The plurality of battery cells are connected to each other in series or in parallel to form a cell assembly, so that the battery module has improved capacity and output. Further, one or more battery modules 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. 
     In the case where the battery pack is configured by connecting the plurality of battery cells in series/in parallel, the battery module formed of at least one battery cell is first configured, and the battery pack is configured by adding other constituent elements by using at least one battery module, which is a general method. The number of battery modules included in the battery pack or the number of battery cells included in the battery module may be variously set according to an output voltage or charge/discharge capacity demanded. 
     Since it is desirable that the medium and large battery modules are manufactured in a lightweight and thin structure, a prismatic battery, a pouch-type battery, and the like that can be stacked with a high degree of integration and have a small weight and large capacity are mainly used as battery cells of the medium and large battery modules. In the meantime, in order to protect the cell stack from outside shock, heat, or vibration, the battery module may include a frame member which receives the battery cell stack in an interior space while covering upper, lower, left, and right surfaces of the battery cell stack. 
     Since several battery cells included inside the battery module have a stacked structure, a venting hole structure may be applied to quickly discharge heat and flames to the outside when ignition occurs in the battery module unit. However, in this case, there is a problem in that foreign substances flow into the venting hole, and rigidity of the battery module is decreased due to the application of the venting hole. 
     The above information disclosed in this section is only for enhancement of understanding of the background of the invention, and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
     SUMMARY 
     The present invention has been made in an effort to provide a battery module which is capable of effectively discharging heat and flames to the outside when ignition occurs in the battery module, maintaining rigidity of the battery module, preventing inflow of foreign substances, and preventing rapid spread of flames, and a battery pack including the same. 
     However, the objective of the exemplary embodiments of the present invention is not limited to the foregoing objective, and may be variously extended within the scope of the technical spirit included in the present invention. 
     An exemplary embodiment of the present invention provides a battery module, including: a battery cell stack including one or more battery cells; and a housing for accommodating the battery cell stack, in which the housing includes a pattern structure in which holes are formed in a repetitive shape in at least one surface, and the battery module further includes an extinguishing sheet disposed between the pattern structure and the battery cell stack. 
     The pattern structure may be a truss structure in which a shape of the hole is a triangle. 
     The housing may be made of a metal. 
     The battery module may further include one pair of end plates disposed at the ends in a longitudinal direction of the battery cell stack, in which the housing may be formed to correspond to four surfaces of the battery cell stack that are not covered by the end plates, and the pattern structure may not be disposed on a surface corresponding to a bottom surface of the battery cell stack among the four surfaces. 
     The pattern structure may be disposed on one surface of the housing corresponding to an upper surface of the battery cell stack. 
     The pattern structure may be disposed on the entirety of the one surface of the housing corresponding to the upper surface of the battery cell stack. 
     The pattern structure may be disposed only on a part of the one surface of the housing corresponding to the upper surface of the battery cell stack. 
     The pattern structure may be disposed on one surface of the housing corresponding to any one of side surfaces of the battery cell stack. 
     The extinguishing sheet may include one or more extinguishing agents selected from the group consisting of inorganic carbonates, inorganic phosphates, and inorganic sulfates. 
     Another exemplary embodiment of the present invention provides a battery pack including: said at least one battery module, and a pack case configured to pack at least one battery module. 
     According to the exemplary embodiments of the present invention, it is possible to effectively disharge heat and flames to the outside when ignition occurs in a battery module, maintain rigidity of the battery module, prevent foreign substances from being introduced, and simultaneously prevent flame from being rapidly spread. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of a battery module according to an exemplary embodiment of the present invention. 
         FIG.  2    is an exploded perspective view of the battery module of  FIG.  1   . 
         FIG.  3    is a top view of the battery module of  FIG.  1   . 
         FIG.  4    is an exploded perspective view of a battery module according to another exemplary embodiment of the present invention. 
         FIG.  5    is an exploded perspective view of a battery module according to still another exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, the present invention will be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown 
     However, the present invention can be variously implemented and is not limited to the following embodiments. 
     Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. 
     In addition, the size and thickness of each configuration shown in the drawings are arbitrarily shown for understanding and ease of description, but the present invention is not limited thereto. In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. In the drawings, for understanding and ease of description, the thickness of some layers and areas is exaggerated. 
     Further, it will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” 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, there are no intervening elements present. Further, in the specification, the word “on” means positioning on or below the object portion, but does not essentially mean positioning on the upper side of the object portion based on a gravity direction. 
     In addition, unless explicitly described to the contrary, the word “comprise”, and variations such as “comprises” or “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. 
       FIG.  1    is a perspective view of a battery module according to an exemplary embodiment of the present invention,  FIG.  2    is an exploded perspective view of the battery module of  FIG.  1   , and  FIG.  3    is a top view of the battery module of  FIG.  1   . 
     As illustrated in  FIGS.  1  to  3   , a battery module  100  according to an exemplary embodiment of the present invention includes a battery cell stack  400  including one or more battery cells, a housing  200  for accommodating the battery cell stack  400 , and a pair of end plates  300  positioned at both ends of the battery cell stack  400  in a longitudinal direction and coupled to openings of the housing  200 . 
     The battery cell stack  400  is an assembly of secondary batteries including a plurality of battery cells  112 . The battery cell stack  400  may include a plurality of battery cells  112 , and each battery cell includes an electrode lead. The batter cells  112  may be the pouch-type battery cell having a plate shape, but are not limited thereto. The electrode lead is a positive electrode lead or a negative electrode lead, and an end of the electrode lead of each battery cell  112  may be bent in one direction, and thus, may be in contact with an end of the electrode lead of another adjacent battery cell  112 . The two electrode leads which are in contact with each other may be fixed by welding and the like, and thus, the battery cells  112  inside the battery cell stack  400  may be electrically connected. 
     Further, a bus bar frame  500  accommodated in the housing  200  may be provided together with the battery cell stack  400 . The bus bar frame  500  may include an upper frame  510  positioned on an upper portion of the battery cell stack  400 , a front fame  520  positioned on a front surface of the battery cell stack  400 , and a rear frame  530  positioned on a rear surface of the battery cell stack  400 . A bus bar  540  connected with the electrode leads of the battery cells configuring the battery cell stack  400  may be mounted to the front frame  520  and the rear frame  530 . 
     The plurality of battery cells  112  are vertically stacked so that the electrode leads are aligned in one direction to form the battery cell stack  400 . The battery cell stack  400  is accommodated in the housing  200  including at least one opening open in the longitudinal direction of the battery cell stack  400 . In this case, the electrode leads are withdrawn to the outside of the housing  200  through the opening, and the withdrawn electrode leads are coupled to the front frame  520  and the rear frame  530  of the bus bar frame  500 , respectively, to be electrically connected with the mounted bus bar  540 . Herein, the bus bar frame  500  may be made of an insulating material, for example, non-conductive synthetic resin, and the bus bar  540  may be made of a conductive metal material. 
     The battery module  100  may include a Flexible Printed Circuit Board (FPCB) (not illustrated) extended and mounted in the longitudinal direction of the housing  200  in the upper portion of the battery cell stack  400  to sense the battery cell  112 . Further, the battery module  100  may include various electronic components, for example, an Internal Circuit Board (ICB) and a Battery Management System (BMS). The electronic components, such as the ICB and the BMS board, may be electrically connected with the plurality of battery cells  112 . 
     In the battery module  100  according to the present exemplary embodiment, the housing  200  may be formed to cover four surfaces, except for both side ends, of the battery cell stack  400 . That is, as illustrated in  FIG.  2   , the battery cell stack  400  may have an upper surface and a bottom surface in the upper portion and the lower portion in the z-axis direction, respectively, and an upper surface  200   a  of the housing  200  may be located at a position corresponding to the upper surface of the battery cell stack  400  and a lower surface  200   b  of the housing  200  may be located at a position corresponding to the bottom surface of the battery cell stack  400 , and one pair of side surfaces  200   c  corresponding to the side surfaces of the battery cell stack  400  may be positioned between the upper surface  200   a  and the lower surface  200   b . In this case, the housing  200  may have a rectangular tube shape as illustrated in  FIG.  2   , but is not limited thereto, and may also have a structure in which a U-shape frame formed of the lower surface  200   b  and one pair of side surfaces  200   c  that are vertically coupled to both sides of the lower surface  200   b  is coupled with an upper plate that is coupled to the U-shape frame to form the upper surface  200   a . In addition, the housing  200  may have a structure in which an inverted U-shaped frame formed of the upper surface  200   a  and both side surfaces  200   c  is coupled with a lower plate forming the lower surface  200   b , but is not particularly limited. Further, although not illustrated, a curve corresponding to the shape of the lower portion of the battery cell  112  included in the battery cell stack  400  is formed inside the lower surface  200   b  of the housing on which the battery cell stack  400  is seated, thereby more stably supporting the battery cell  112 . Further, although not illustrated, a heat conductive resin layer may also be formed between the battery cell stack  400  and the lower surface  200   b  to discharge heat generating from the battery cells  112 . 
     The housing  200  may be made of a metal material. The metal material may be one or more selected from steel and aluminum. End plates  300  are coupled to each open ends of the housing  200 , respectively. The end plate  300  may be made of a metal material to have rigidity to protect the components, such as the battery cell stack  400  and the bus bar frame  500 , inside thereof. The end plate  300  made of the metal material may be coupled to the housing  200  which is also made of the metal material, by a method of welding and the like. 
     The housing  200  may include a pattern structure  210  formed of holes  210   a  having a repetitive shape on at least one surface. By including the pattern structure  210  in the housing  200  made of the metal material, when an issue, such as ignition, occurs inside the battery module  100 , gas may be easily discharged through the holes  210   a  of the pattern structure  210 . That is, the holes  210   a  of the pattern structure  210  may serve as venting holes. Further, even though the pattern structure  210  including the plurality of holes  210   a  is formed, the holes  210   a  have a repetitive shape, thereby maintaining rigidity of the battery module  100 . Particularly, the pattern structure  210  may have a truss structure in which the holes  210   a  have a triangular shape. That is, as illustrated in  FIG.  3   , in the case where the pattern structure  210  has the truss structure in which a beam made of a metal is connected so that triangular holes  210   a  are formed, even if external force is applied, the shape of the pattern structure  210  is not changed easily, so that it is possible to maintain rigidity. Accordingly, one surface of the housing  200  (in the present exemplary embodiment, the upper surface  200   a ) has an open portion that serves as the venting hole, and simultaneously, it is possible to maintain rigidity of the housing  200  by the pattern structure  210 . 
     An extinguishing sheet  600  can be disposed between the pattern structure  210  and the battery cell stack  400 . By the disposition of the extinguishing sheet  600 , it is possible to prevent foreign substances from being introduced from the outside through the holes  210   a  of the pattern structure  210 . Further, when ignition and the like occur inside the battery module  100 , carbon dioxide gas is discharged under thermal runaway conditions by an extinguishing agent included in the extinguishing sheet  600 , so that the battery module  100  has a self-extinguishing function capable of suppressing the combustion reaction itself. This may weaken or eliminate the flames, thereby delaying the spread of the flames to the surroundings. Extinguishing agents may be included in the extinguishing sheet  600 , and as the extinguishing agent, one or more selected from the group consisting of inorganic carbonates, inorganic phosphates, and inorganic sulfates may be used, but is not particularly limited. 
     As described above, according to the exemplary embodiment of the present invention, the battery module includes the pattern structure  210  in which the holes  210   a  are formed in a repetitive shape in at least one surface of the housing  200  and includes the extinguishing sheet  600  disposed between the pattern structure  210  and the battery cell stack  400 , so that even though the battery module  100  includes the plurality of holes  210   a  acting as the vent holes when ignition occurs inside the battery module  100 , it is possible to maintain rigidity of the housing  200  and simultaneously prevent foreign substances from being introduced from the outside. Further, it is possible to decrease the speed at which the flames spread by the extinguishing sheet  600 , thereby improving safety of the battery module  100 . 
     Next, another exemplary embodiment and still another exemplary embodiment will be described with reference to  FIGS.  4  and  5   . 
       FIG.  4    is an exploded perspective view of a battery module according to another exemplary embodiment of the present invention, and  FIG.  5    is an exploded perspective view of a battery module according to still another exemplary embodiment of the present invention. 
     As illustrated in  FIG.  4   , in another exemplary embodiment of the present invention, a pattern structure  210  formed of holes  210   a  in a repetitive shape is formed in any one of side surfaces  200   c  of a housing  200 . In this case, an extinguishing sheet  600  may be disposed between the side surface  200   c  in which the pattern structure  210  is formed and a battery cell stack  400 . Even in the case where the pattern structure  210  is formed in the side surface  200   c  as described above, it is possible to maintain rigidity of the housing  200  and simultaneously, the holes  210   a  included in the pattern structure  210  may act as the vent holes when ignition occurs inside a battery module  100 . Further,  FIG.  4    illustrates the pattern structure  210  formed only in the side surface  200   c , but the pattern structure  210  may be formed in the side surface  200   c  and an upper surface  200   a  at the same time, and the pattern structure  210  may be formed in both side surfaces  200   c . However, in the case of a lower surface  200   b  where the battery module  100  is mounted to a battery pack or a device, the lower surface  200   b  is not suitable for discharging flames and the like to the outside when ignition occurs, so that it is preferable that the pattern structure  210  is formed in the portions except for the lower surface  200   b . 
     Further, as illustrated in  FIG.  5   , in still another exemplary embodiment of the present invention, a pattern structure  210  formed of holes  210   a  in a repetitive shape is formed only in a part of an upper surface  200   a  of a housing  200 . That is, as illustrated in  FIG.  5   , the pattern structure  210  and the portion in which the pattern structure is not formed may be repeated in a stripe shape, and contrary to this, the pattern structure  210  may be applicable only to a center portion of the upper surface  200   a . By the foregoing configuration, it is possible to maintain rigidity of the housing  200 , and simultaneously the holes  210   a  included in the pattern structure  210  may act as the vent holes when ignition occurs inside the battery module  100 . Further, in this case, an extinguishing sheet  600  may be disposed between the upper surface  200   a  and a battery cell stack  400 .  FIG.  5    illustrates that extinguishing sheet  600  corresponds to the whole upper surface  200   a , but the present invention is not limited thereto, and any position that can cover all of the holes  210   a  included in the pattern structure  210  may be appropriately applied. 
     As described above, according to the exemplary embodiments of the present invention, the battery module includes the pattern structure  210  in which the holes  210   a  are formed in a repetitive shape in at least one surface of the housing  200  and includes the extinguishing sheet  600  disposed between the pattern structure  210  and the battery cell stack  400 , so that it is possible to maintain rigidity of the housing  200  and simultaneously, the holes  210   a  included in the pattern structure  210  may act as the vent holes when ignition occurs inside the battery module  100 , thereby improving safety of the battery module  100 . Further, it is possible to decrease the speed of the spread of flames by the extinguishing sheet  600 , thereby further improving safety of the battery module  100 . 
     In the meantime, the battery module according to the exemplary embodiment of the present invention may be packed in one or more cases to form a battery pack. 
     The battery module and the battery pack including the same described above may be applied to various devices. As the device, transport means, such as an electric bicycle, an electric vehicle, and a hybrid vehicle, are applicable, but the present invention is not limited thereto, and the present invention is applicable to various devices capable of using a battery module and a battery pack including the same, which also belongs to the scope of the present invention. 
     Although exemplary embodiments of the present invention has been described in detail, the scope of the present invention is not limited by the embodiment. Various changes and modifications using the basic concept of the present invention defined in the accompanying claims by those skilled in the art shall be construed to belong to the scope of the present invention.