Patent Publication Number: US-2023155207-A1

Title: A battery module

Description:
TECHNICAL FIELD 
     The present subject matter relates to a battery module. More particularly, heat dissipation in the battery module is disclosed. 
     BACKGROUND 
     In recent years, rechargeable energy storage devices have been widely used as an energy source for a number of electronic and electrical units, hybrid and electric vehicles. Commonly used rechargeable energy storage devices include, for example, nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, and lithium rechargeable batteries. Lithium rechargeable energy storage devices are widely used in electric and hybrid vehicles because they are rechargeable, they can be made in a compact size with large capacity, they have a high operation voltage, and they have a high energy density per unit weight. 
     An existing energy storage device comprises one or more energy storage cells, such as, lithium ion battery cells enclosed within a casing. The electrochemical reactions with the lithium ion battery cells are responsible for the voltage and the current generated by the energy storage device. Also, during charging of the energy storage device, electrochemical reactions occur within the lithium ion battery cells. These electrochemical reactions are highly exothermic and the lithium ion battery cells tend to heat up during the course of normal operation. The increased temperatures of the lithium ion battery cells degrade the electrical performance of the energy storage device and may lead to catastrophic failure of the energy storage devices. There is a need to dissipate the generated heat and cool the lithium ion battery cells of the energy storage device for the safety and longevity of the energy storage device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The detailed description is described with reference to the accompanying figures. The same numbers are used throughout the drawings to reference like features and components. 
         FIGS.  1 A- 1 B  exemplarily illustrate perspective views of a battery module, as pear an embodiment of the present invention; 
         FIG.  2    exemplarily illustrates an exploded perspective view of the battery module illustrated in  FIGS.  1 A- 1 B ; 
         FIG.  3    exemplarily illustrates a front perspective view of a casing of the battery module; 
         FIG.  4    exemplarily illustrates a top perspective view of a cell holder in the battery module, as per an embodiment of the present invention; 
         FIG.  5    exemplarily illustrates a plan view of an assembly of an interconnect sheet and a thermal interface member of the battery module; 
         FIG.  6    exemplarily illustrates a top perspective view of a flexible member of the battery module; and 
         FIG.  7    exemplarily illustrates a flowchart depicting a method comprising steps for assembly of the battery module. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Currently, for cooling the lithium ion battery cells in the energy storage device, coolant channels with air or a coolant liquid are designed around individual battery cells or a cluster of battery cells. However, the design of the coolant channels within the casing of the energy storage devices makes the energy storage device bulky and no longer compact for space-constrained varied applications. Also, maintaining the temperatures, the pressures, and the sealing of the coolant flow into and outside the energy storage device adds to the heat dissipation problem being addressed. 
     In another implementation for cooling of the energy storage device, and in turn the lithium ion battery cells, a heat exchange member in thermal contact with the casing of the energy storage device is used. The heat dissipated from the lithium ion battery cells has to traverse through air-filled gap between the cells and the casing. The heat transfer between the battery cells and the casing is not efficient since the air is a poor conductor of heat. In order to ensure that heat is effectively dissipated from the battery cells, it is essential to ensure that the heat generating battery cells are reliably secured to be in thermal contact with the heat exchange member proximal to the casing. Further, there is also a need to ensure that there is no air gap between an upper surface of the lithium ion battery cells and an inner surface of the outer casing, in order to ensure that heat is effectively transmitted to the metallic casing. 
     Typically, fasteners or clips are used to secure the lithium ion battery cells proximal to the casing of energy storage device for establishing thermal contact between the battery cells and the heat exchange members. Particularly, the use of clips/fasteners only aid in establishing thermal contact of side and/or front and/or rear surfaces of the battery cells with the casing, and through the casing with the heat exchange member. Further, based on the application of the energy storage device, the capacity of the energy storage device is varied. Based on the capacity of the energy storage device, the number of battery cells, the mass of the battery cells, and the capacity of the battery cells, etc., are varied. If battery cells with reduced size or mass are to be enclosed within an existing casing, a gap may be formed between the casing and the battery cells. Such gaps will result in ineffective heat transfer from the energy storage cells in the energy storage device. Also, due to variation in the shape and size of the fasteners, it is difficult to establish consistent and effective thermal contact between the battery cells and the heat exchange members. 
     Typically, heat conductive packaging material may be used to establish thermal contact of the battery cells with a surface of the outer conductive casing. The heat conductive packaging material needs to be uniformly distributed along the length of the casing between the casing and the surface of the battery cells using a fastening means. However, the packaging material increases the weight, the manufacturing cost, and the assembling cost of the energy storage device. Also, while loading or unloading the assembly of the energy storage cells into the casing, the packaging material may hinder the ease in pushing in or pulling out of the energy storage cells from the casing. If the heat conductive packaging material that is rigid and firm is used, it may not allow for the flexibility of using an existing casing for different assemblies of the energy storage cells. This may lead to manufacture of different casings for different assemblies of the energy storage cells increasing material cost and manufacture cost of entities. Thus, to address this problem, the packaging material has to be made adequately flexible as well as rigid to not deform, while loading and unloading of the assembly of the energy storage cells with efficient heat transfer properties. Also, the packaging material needs to take care of the marginal deviation or tolerances in design of the casing or the design of cell holders holding the battery cells for effective heat transfer from the energy storage cells to the casing. 
     Therefore, there exists a need for an improved design of an energy storage device with thermal contact between the battery cells and the casing of the energy storage device for efficient heat transfer from the battery cells with ease and safety during assembly, use, maintenance, and servicing of the energy storage device overcoming all problems disclosed above as well as other problems of known art. 
     The present subject matter discloses an energy storage device, that is, a battery module with battery cells in gap-less thermal contact with a casing of the battery module for effectively as well as efficiently dissipating the heat generated by the battery cells and cooling the battery cells for safety, longevity, and ease and safety during assembly, use, maintenance, and servicing of the energy storage device. Such a battery module may be employed in powered devices, such as, vehicles, for example, electric vehicle, hybrid electric vehicles, IC engine vehicles, etc. 
     In an embodiment of the present invention, a battery module for a powered device is disclosed. The battery module comprises multiple cells positioned in multiple cell holders. A casing encloses the cells in the cell holders. The casing comprises a first inner surface, a first outer surface, and a second inner surface. The battery module further comprises a cell support structure integrated with the first inner surface of the casing for establishing a thermally conducting and electrically insulating contact between the cells and the first inner surface. The battery module, in an embodiment, further includes a flexible member positioned between the second inner surface of the casing and one of the cell holders for exerting a pre-load pressure on the cell holders to establish the thermally conducting and electrically insulating contact between the cells and the first inner surface. The flexible member is longitudinally slacked forming a series of alternating crests and troughs. 
     In an embodiment, the battery module further comprises at least one thermal interface member in contact with at least one of the one or more cell holders for thermally conducting heat generated by the plurality of cells positioned in the one or more cell holders. In one embodiment, one thermal interface member is positioned between the flexible member and one of the cell holders. In this embodiment, another thermal interface member is positioned between one of the cell holders and the cell support structure. In another embodiment, only one thermal interface member is positioned between one of the cell holders and the cell support structure. The thermal interface member is firm at room temperature and softens and fills the gap between one of the one or more cell holders and the cell support structure at higher temperatures for preventing entrapment of air in the path of conduction of heat generated by the plurality of cells. 
     In an embodiment, the casing further comprises a first outer surface having a heat dissipating structure for dissipating heat generated by the cells in thermally conducting and electrically insulating contact with the first inner surface of the casing to external environment. The heat dissipating structure is multiple fins, coolant channels, or/and an aeration device. In an embodiment, a coupling member ( 208 ) is positioned between the flexible member and one of the one or more cell holders for efficiently packaging the plurality of cells to establish the thermally conducting and electrically insulating contact between the plurality of cells and the first inner surface. In an embodiment, a coupling member is positioned between the inner surface of the casing and the flexible member. The flexible member is inserted into a gap between the second inner surface of the casing and one of the cell holders after the assembly of the cell holders and the at least one thermal interface member. 
     In another embodiment, a method of assembly of a battery module is disclosed. The method comprises the steps of: obtaining a casing and a plurality of cells enclosed in a one or more cell holders, wherein the casing comprises a first inner surface, a first outer surface, and a second inner surface, and wherein a cell support structure is integrated with the first inner surface of the casing. Further, positioning the cell holders in the casing, wherein the plurality of cells in one of the one or more cell holders in a thermally conducting and electrically insulating contact with the cell support structure. Further, sliding a flexible member between the second inner surface of the casing and another one of the one or more cell holders for exerting pressure on the one or more cell holders to establish the thermally conducting and electrically insulating contact between the plurality of cells and the cell support structure. 
     In an embodiment, the method further comprises a step of inserting at least one thermal interface member between the flexible member and the another one of the one or more cell holders. In an embodiment, the method further comprises a step of inserting at least one thermal interface member between the one of the one or more cell holders and the cell support structure. In an embodiment, the method further comprises inserting a coupling member between the second inner surface of the casing and the flexible member. In an embodiment, the method comprises a step of inserting a coupling member between the flexible member and one of the one or more cell holders. In an embodiment, a heat dissipating structure is integral to a first outer surface of the casing for dissipating heat generated by the plurality of cells in the thermally conducting and electrically insulating contact with the first inner surface of the casing to external environment. The heat dissipating structure is at least one of a plurality of fins, a plurality of coolant channels, and an aeration device. 
       FIGS.  1 A- 1 B  exemplarily illustrate perspective views of a battery module  100 , as per an embodiment of the present invention.  FIG.  1 A  illustrates a top perspective view of the battery module  100 .  FIG.  1 B  also illustrates a top perspective view of the battery module  100 , with the battery module  100  in  FIG.  1 A  in an inverted orientation. As exemplarily illustrated in  FIG.  1 A , the battery module  100  comprises a casing  101  and a first end cover  105 . The casing  101  is a hollow rectangular cover enclosing multiple cells and other electrical and electronic components, such as, a BMS board of the battery module  100 . The casing  101  comprises enclosing walls  102  and  108  exemplarily illustrated in  FIG.  1 B , peripheral walls  103  and  104  between the enclosing walls  102  and  108 , and open ends (not shown). End covers of the battery module  100  close the open ends of the casing  101 . The casing  101  has mounting provisions, such as,  106  to mount the end covers, such as, the first end cover  105  and the second end cover (not shown) at the open ends of the casing  101  using attachment means. The end covers have external electrical connections, such as,  107  of the battery module  100  for charging and discharging of the battery module  100 . As exemplarily illustrated, an outer surface of the enclosing wall  102  comprises a dovetail pattern that facilitates in easy mounting and unmounting of the battery module  100  in a designated space in a powered device. In an embodiment, both the enclosing walls  102  and  108  have the dovetail pattern. Corresponding, inner surfaces of the enclosing walls  102  and  108  also have the dovetail pattern. In an embodiment, the outer surfaces of the peripheral walls  103  and  104  also have a dovetail pattern on them. 
     As exemplarily illustrated in  FIG.  1 B , the outer surface of the other enclosing wall  108  of the casing  101  comprises a heat dissipating structure  109 , such as, fins. The cells (not shown) enclosed in the casing  101  generate heat and the heat is transferred to the casing  101  of the battery module  100  to be dissipated to the surroundings of the battery module  100 . The heat dissipating structure  109  on the outer surface of the enclosing wall  108  facilitates the exchange of the heat transferred to the casing  101  with the air or a liquid coolant. The heat dissipating structure  109  may be the fins, coolant channels for air or a liquid, and/or an aeration device. The heat dissipating structure  109  extracts the heat in the casing  101  and cools the battery module  100  using either natural convection or forced convection based on the installation and the application of the battery module  100 . From the cells to the casing  101 , the heat is transferred using conduction due to thermal contact established between the cells and the casing  101  by the construction of the battery module  100  as will be disclosed in  FIGS.  2 - 7   . For effective thermal conduction, the casing  101  is made of a heat conducting material and is formed using an extrusion process. The heat generated by the cells and also by other electronic components, such as, the BMS board, when dissipated to the surroundings, ensures efficient performance of the battery module  100 . Hereafter, the outer surface of the enclosing wall  102  is referred to as a second outer surface and an inner surface of the enclosing wall  102  facing towards the cells is referred to as a second inner surface. Similarly, hereinafter the outer surface of the enclosing wall  108  is referred to as a first outer surface and an inner surface of the enclosing wall  108  facing towards the cells is referred to as a first inner surface. 
       FIG.  2    exemplarily illustrates an exploded perspective view of the battery module  100  illustrated in  FIGS.  1 A- 1 B . As exemplarily, the battery module  100  comprises the first end cover  105 , the second end cover  110 , the casing  101 , and a battery pack  202 . The external casing  101  encloses the battery pack  202  from top and bottom. The second end cover  110  and the first end cover  105  are fastened at the open ends of the casing  101  and enclose the battery pack  202  from rear and front respectively. The battery pack  202  comprises a plurality of cells  203  arranged in a particular sequence between cell holders  204  and  205 . The cells  203  are electrically connected in series and/or parallel configuration to form an array of cells using one or more interconnect sheets, such as,  206 . Such arrays of cells are electrically connected to a battery management system (BMS)  201  within the battery module  100 . The BMS  201  is a printed circuit board with one or more integrated circuits integrally. The battery pack  202  has mounting provisions for the BMS board  201 . The BMS board  201  is screwably attached to the cell holders  204  and  205  of the battery pack  202 . The BMS board  201  is located between the battery pack  202  and the first end cover  105 .The dovetail pattern formed on the interior side of the casing  101  allows easy sliding of the battery pack  202  into the casing  101 . 
     The first outer surface  108   b  of the casing  101  comprises the heat dissipating structure  109  as exemplarily illustrated in  FIG.  1 B . On the first inner surface  108   a , a cell support structure  210  is integrated to the casing  101 . In addition to the battery pack  202 , a thermal interface member  207  and a flexible member  209  are positioned within the casing  101 . In an embodiment, a coupling member  208  is also positioned in the casing  101  as exemplarily illustrated. As exemplarily illustrated, the thermal interface member  207 , the flexible member  209 , the cell support structure  210 , and the coupling member  208  are positioned around the plurality of cells  203  to establish thermal contact of the cells  203  to the heat dissipating structure  109  on the body of the casing  101 . 
     As exemplarily illustrated, the thermal interface member  207  is positioned in contact with the interconnect sheet  206 , proximal to the cell holder  205 . In an embodiment, another thermal interface member, such as,  207  may be positioned underneath the cells  203 , proximal to the cell holder  204  and the cell support structure  210 . In an embodiment, a thermal interface member, such as,  207  may be positioned only between the cell holder  204  and the cell support structure  210 . The flexible member  209  is positioned proximal to second inner surface  102   a . The coupling member  208  is positioned between the flexible member  209  and the thermal interface member  207 . 
       FIG.  3    exemplarily illustrates a front perspective view of the casing  101  of the battery module  100 . The casing  101  of the battery module  100  comprises the enclosing walls  102  and  108 , the peripheral walls  103  and  104 , and the open ends  301  and  302 . The open ends  301  and  302  have the mounting provisions, such as,  303  for mounting the end covers  105  and  110  as exemplarily illustrated in  FIG.  2   . In the inner surface  108   a  of the enclosing wall  108 , the cell support structure  210  is integrated. In an embodiment, the cell support structure  210  is modular and may be positioned above the first inner surface  108   a  of the casing  101 . The cell support structure  210  is a raised slab, of a predetermined thickness, onto which the cell holder such as,  204  is positioned. The cell support structure  210  is made of a thermally conductive material, such as, Aluminum. The cell support structure  210  establishes contact between the cells  203  in the cell holder  204  and the casing  101  and in turn with the heat dissipating structure  109  on the first outer surface  108   b . The cell support structure  210  transfers the heat to the first outer surface  108   b  and the heat dissipating structure  109 , such as, the fins allowing natural air to cool the first outer surface  108   b . The heat dissipating structure  109  on the first outer surface  108   b  guides cool air or liquid around the first outer surface  108   b . The temperature of the cell support structure  210  is reduced and in turn the cells  103  that are in contact with the cell support structure  210 . 
     In an embodiment, a thermal interface member  207  may be positioned beneath the cell holder  204  and in thermal contact with the cells  203 . The thermal interface member  207  is, then, in thermal contact with the cell support structure  210 . Such an assembly of the cell holder  204 , the thermal interface member  207 , and the cell support structure  210  ensures there no gap for air to accumulate in the casing  101  for effective heat transfer from the cells  203  to the casing  101 . The cell support structure  210  is strong and adequately rigid to not deform under frequent loading and unloading of the battery pack  202  from the casing  101  as well as at higher temperatures. In an embodiment, the cell support structure  210  has guides on its sides to aid in loading and unloading of the battery pack  202  from the casing  101 . In an embodiment, the cell support structure  210  extends over the area of the first inner surface  108   a.    
       FIG.  4    exemplarily illustrates a perspective view of a cell holder  204  of a battery module  100  as exemplarily illustrated in  FIG.  2   . As disclosed earlier, the battery pack  100  comprises the cell holders  204  and  205  and the BMS board  201  is removably attached to the cell holders  204  and  205 . The cell holder  204  is a bottom cell holder and the cell holder  205  is a top cell holder. Each of the cell holders, such as,  204  comprise placeholders  401  for holding the cells  203  in each cell holder  204 . Each of the cell holders  204  comprises a planar surface, such as,  402  with the placeholders  401  and raised walls, such as,  403 ,  404 ,  405 , and  406  at the sides of the planar surface  402 . The bottom cell holder  204  is positioned at the bottom of the cells  203  and the top cell holder  205  is positioned on top of the cells  203 . The cell holders  204  and  205  are fixed together using a plurality of fasteners to tightly hold the cells  203  in the placeholders  401 . The raised walls, such as,  403 ,  404 ,  405 , and  406  of the cell holders  204  and  205  come in contact with each other, when the cell holders  204  and  205  are fixed together. To fasten the cell holders  204  and  205  together, recesses to position the fasteners are provided in the cell holders  204  and  205 . As an embodiment, the cell holders  204  and  205  may be rectangular in shape and holding cylindrical cells  203  in the placeholders  401 . The bottom cell holder  204  is exemplarily illustrated in  FIG.  4   . The placeholders  401  are tubular structures on the planar surface  402  with openings for the terminals of the cells  203  to protrude and make contact with the interconnect sheets  206 . The construction of the top cell holder  205  is similar to the construction of the bottom cell holder  204  exemplarily illustrated on  FIG.  2   . 
     One or more interconnect sheets, such as,  206  that connect the terminals of the cells  203  in series and/or parallel connection is positioned on the rear side of the planar surface  402 . The rear side of the planar surface  402  with the raised walls  403 ,  404 ,  405 , and  406  can safely hold the interconnect sheets  206 . Each interconnect sheet  206  electrically connects the terminals of a cluster of cells  203 . In an embodiment, one or more interconnect sheets  206  is positioned only on the rear planar surface, such as,  402  of either of the top cell holder  205  or the bottom cell holder  204 . In an embodiment, one or more interconnect sheets  206  may be positioned in the rear surface of the planar surface  402  of both the cell holders  204  and  205 . The interconnect sheet  206  is electrically conductive and connects the terminals of the cells  203  to the electrical connections  107  of the battery module  100 . Also, the interconnect sheet  206  is thermally conductive. In an embodiment, the interconnect sheet  206  has a profile to the lock the cells  203  in the cell holders  204  and  205 . Since, the interconnect sheet  206  is in direct contact with the terminals of the cells  203 , the heat generated by the cells  203  is transferred to the interconnect sheet  206  at the terminals. Further, the interconnect sheet  206  in the bottom cell holder  204  is in contact with the thermal interface member  207  or the cell support structure  210  directly and transfers the heat to the first inner surface  108   a  and subsequently to the first outer surface  108   b  of the casing  101 . The interconnect sheet  206  is rigid and is made of electrically and thermally conductive material, such as, copper, nickel, etc. In an embodiment, the battery pack  202  further comprises a protective sheet (not shown) positioned above the interconnect sheet  206  of the battery pack  202  for protecting the soldered points of electrical connection on the interconnect sheet  206 . The protective sheet (not shown) is electrically insulated, while being thermally conductive. The protective sheet is also accommodated in the rear side of the planar surface  402  and in direct contact with the interconnect sheet  206 . In an embodiment, the thermal interface member  207  may be positioned on the protective sheet. 
       FIG.  5    exemplarily illustrates a plan view of an assembly  500  of the interconnect sheet  206  and the thermal interface member  207  of the battery module  100 . As exemplarily illustrated, the thermal interface member  207  is positioned in direct contact with the interconnect sheets, such as,  206 . In an embodiment, another thermal interface member (not shown) is positioned in the rear of the planar surface  302  of each of the top cell holder  205  as exemplarily illustrated in  FIG.  2    and the bottom cell holder  204 . In an embodiment, the battery module  100  comprises only one thermal interface member  207  and the thermal interface member  207  is positioned between the bottom cell holder  204  and the cell support structure  210  of the casing  101 . The thermal interface member  207  is electrically insulating and thermally conductive. The thermal interface member  207  establishes direct thermal contact between the terminals of the cells  203  between the top cell holder  205  and the bottom cell holder  204  with the cell support structure  210  integrated to the first inner surface  108   a  of the casing  108 . The thermal interface member  207  is pre-formed and removably positioned between the bottom cell holder  204  and the cell support structure  210 . In an embodiment, the thermal interface member  207 , made of materials, such as, silicone, rubber, that adheres to the rear of the planar surface  302  of the bottom cell holder  204 . In an embodiment, the thermal interface member  207  is relatively firm or stiff at room temperatures and softens and fills the gap between the bottom cell holder  204  and the cell support structure  210  at higher temperatures. Since the thermal interface member  207  is electrically insulating, the thermal interface member  207  prevents occurrence of short circuit between the cells  203  in the bottom cell holder  204  and the cell support structure  210  of the casing  101 . In an embodiment, the thermal interface member  207  has cut-outs corresponding to the cut-outs in one or more interconnect sheets, such as,  206  for heat and reaction gases in the cells  203  to exhaust out of the cell holders  204  and  205 . 
       FIG.  6    exemplarily illustrates a top perspective view of the flexible member  209  of the battery module  100 . As exemplarily illustrated in  FIG.  2   , the flexible member  209  is positioned between the second inner surface  102   a  of the casing  101  and the coupling member  208 . In an embodiment, the flexible member  209  is positioned between the second inner surface  102   a  of the casing  101  and the top cell holder  205  of the battery pack  202 . In another embodiment, the flexible member  209  is in thermal contact with the second inner surface  102   a  and the protective sheet (not shown) of the battery pack  202  placed in the top cell holder  205 . In an embodiment, the flexible member  209  is positioned between the second inner surface  102   a  and the thermal interface member  207  in proximity with the top cell holder  205 . In another embodiment, the flexible member  209  may be positioned between sides of the battery pack  202  and the peripheral walls  103  and  104  of the casing  101 . The flexible member  209  is a thermally conductive member that exerts a compressive force against the battery pack  202 . The dimensions, such as the length and breadth of the flexible member  209  are larger than the corresponding dimensions of the casing  101 . In an embodiment, the dimensional profile of the flexible or compliant or elastic member  209  is chosen based on the compressive force to be applied on the battery pack  202 . The compressive force applied on the battery pack  202  or the top cell holder  205  pushes the battery pack  202  towards the thermal interface member  207  positioned underneath the bottom cell holder  204 . The thermal interface member  207  is then in thermal contact with the cell support structure  210  integrated with the casing  101 . Thus, the flexible or elastic member  209  ensures the thermal contact of the thermal interface member  207  with the cell support structure  210 . In an embodiment, multiple flexible members, such as,  209  may be inserted into the casing  101 . The flexible member  209  is compressed while assembling the battery pack  202  in the casing  101 . 
     As exemplarily illustrated, the flexible member  209  is longitudinally slacked forming a series of alternating crests  602  and troughs  601 . On a top surface  603 , the flexible member  209  comprises a series of depressions  601   a  in the troughs  601  resulting in bulges at the corresponding locations on the rear side of the top surface  603 . The longitudinally slacked flexible member  209  allows for insertion of the flexible member  209  into the casing  101  by compressing it longitudinally. Following this, the flexible member  209  stretches longitudinally to occupy the space between the peripheral walls  103  and  104  of the casing  101 . The crests  602  and the troughs  601  occupy the spaces between the second inner surface  102   a  of the casing  101  and the battery pack  202 . The bulges on the rear side of the top surface  603  exert compressive force on the battery pack  202  underneath the flexible member  209 . In an embodiment, the crests  602  and the troughs  601  occupy the spaces between the second inner surface  102   a  of the casing  101  and the coupling member  208  In an embodiment, the crests  602  and the troughs  601  occupy the spaces between the second inner surface  102   a  of the casing  101  and the thermal interface member  207  positioned on the cell holder  205 . The flexible member  209 , is for example, an elastic spring plate. 
       FIG.  7    exemplarily illustrates a flowchart  700  depicting a method comprising steps for assembly of the battery module  100  exemplarily illustrated in  FIG.  2   . The method comprises: at step  701 , obtaining a casing  101  and multiple cells  203  enclosed in multiple cell holders  204  and  205  as exemplarily illustrated in  FIG.  2   . The casing  101  comprises the first inner surface  108   a  and the second inner surface  102   a . The cell support structure  210  is integrated with the first inner surface  108   a  of the casing  101 . At step  702 , the cell holders  204  and  205  with the cells  203  are positioned in the casing  101 . The cells  203  between the cell holders  204  and  205  are in thermal contact with the cell support structure  210 . At step  703 , a flexible member  209  is slid between the second inner surface  102   a  of the casing  101  and one of the cell holders, that is, the top cell holder  205  to obtain the battery module  100 . The flexible member  209  exerts pressure on the cell holders  204  and  205  to establish positive thermal contact between the cells  203  and the cell support structure  210 . 
     In an embodiment, at least one thermal interface member  207  is inserted between the flexible member  209  and the top cell holder  205  in the battery module  100 . In another embodiment, the thermal interface member  207  is inserted between the bottom cell holder  204  and the cell support structure  210 . In an embodiment, the assembly of the battery module  100  further comprises a step of inserting a coupling member  208  between the second inner surface  102   a  of the casing  101  and the flexible member  209 . In another embodiment, as exemplarily illustrated in  FIG.  2   , the coupling member  208  is inserted between the flexible member  209  and one of the cell holders, such as, the top cell holder  205 .The assembly of the battery module  100  further comprises a step of integrating a heat dissipating structure  109  to a first outer surface  108   b  of the casing  101  for dissipating the heat generated by the cells  203  in thermal contact with the first inner surface  108   a  of the casing  101 , to external environment. The heat dissipating structure  109  is one of fins, coolant channels, and an aeration device. 
     The different embodiments of the battery modules with various orders of assembly of the thermal interface member, the flexible member, the coupling member, the cell support structure, and the heat dissipating structure provides technical advancements in the field of heat management in battery modules. The casing of the battery module with the integrated cell support structure ensures firm thermal contact between the cells and the casing. The integrated cell support structure is formed during the process of molding of the casing or may be integrated on site using suitable attachment means. The integrated cell support structure during the process of molding saves the cost of extra components such as fasteners, adhesives to attach the cell support structure to the casing. The thermal interface member between the interconnect sheet of the cell and the cell support structure ensures electrical insulations of the cell terminals, avoiding any instance of electrical short circuit in the battery module. However, the thermal interface member provides thermal conductivity, effectively transferring heat from the cell terminals to the cell support structure. The heat dissipating structure formed on the first outer surface of the casing enables cooling of the casing from outside, whose effect is transferred to the terminals of the cells through the thermal contact of the cell support structure with the thermal interface member and the interconnect sheet connecting the cell terminals. The first outer surface of the casing has the flexibility of accommodating different heat dissipating structures, such as, fins, aeration device, coolant channels due to the wider surface area of the first outer surface. 
     The positioning of the flexible member on top of the cell holders in proximity with the second inner surface of the casing results in generating an elastic push force or pre-load onto the cell holders to have thermal contact between the cell terminals with the thermal interface member and the cell support structure in the casing. The slacked flexible member when inserted in the casing experiences a tension or pre-load due to the tight assembly of components within the casing. This tension translates into the push force on the cell holders. In case, still an air gap remains after assembly of the thermal interface member, the flexible member, and the cell support structure, the coupling member is additionally inserted into the casing for a tight packaging of the cells and associated components in the casing to ensure thermal contact of the cells with the thermal interface member, in turn with the cell support structure thereby additionally addressing any geometrical tolerance variations. The coupling member resembles the cell support structure in material and dimensions. 
     Such an assembly of the battery module ensures effective heat transfer between the cells and the heat dissipating structure on the casing. The heat dissipated effectively ensures thermal stability and durability of the battery module. The coupling member, the flexible member, the thermal interface member, and the cell support structure package the cells efficiently, making the battery module mechanically stable, impact resistant, and vibration proof The resilient nature of the flexible member acts as a vibration absorber that is experienced by the casing of the battery module. The cell support structure allows easy sliding in and sliding out of the battery pack from the casing. During the assembly of the battery module, the insertion of the flexible member is simple and requires only sliding to fit into the space between the second inner surface and the cell holders. In cases where the same casing is used for battery packs of different capacity, the flexible member in multiple units and/or along with one or more coupling members will fill the gap between the battery pack and the casing. In an embodiment, only dimensions of the flexible member are to be altered if the gap between the battery pack and the casing is varied. By retaining the same flexible or elastic member or altering the flexible member and/or quantity of elastic member and/or coupling member, the cost of redesigning the casing and the cell holders is completely avoided, thereby saving manufacturing cost of the new battery module and giving tremendous flexibility for a manufacturer to have variety of battery packs with various capacities to cater to different product variants, different markets etc. without compromising on the complexity of manufacturing, increasing variety as well as complexity of assembly while overcoming the contradictory requirements of effective heat dissipation while still being electrically insulating. 
     Improvements and modifications may be incorporated herein without deviating from the scope of the invention.