Patent Publication Number: US-2023155220-A1

Title: Battery lid and battery assembly

Description:
TECHNICAL FIELD 
     This invention relates to battery cells and batteries that are used in applications such as electric vehicles, portable devices, and power storage, but not limited thereto. In particular, the invention relates to a battery lid which is adapted to be mounted in a battery cell housing to cover its opening. The invention relates also to a battery cell assembly. 
     BACKGROUND 
     A battery cell refers to a single anode and cathode that are separated by an electrolyte and used to store the chemical energy and then transforms the stored chemical energy into an electrical energy. The battery cells may be considered as building blocks of battery pack or battery cell assemblies, which may consist of one or more different types of battery cells, such as cylindrical or prismatic battery cells, where one battery cell typically consists of a negative anode, a positive cathode, an electrolyte, an insulator, a housing, and terminals. For example, in electric vehicles, battery packs or battery cell assemblies generally include a plurality of individual battery cells connected in series or in parallel to form a battery cell module, which may be configured in series, in parallel, or a mixture of both. 
     The operation of any battery cell generates heat due to the losses as current flows through the internal resistance of the battery cell whether it is being charged or discharged, for example. The thermal condition of the battery is also dependent on its environment. For example, when multiple battery cells are connected either in series or in parallel, they typically generate a large amount of heat and cause a temperature rise during battery charging and discharging. The environmental conditions to which the battery cells are exposed may also affect the temperature of each battery cell. For example, in electric vehicles, battery cells heat up during driving, when the electricity is flowing out, and during charging, when electricity is flowing in. If the battery cell malfunctions, the temperature may also rise, and a sudden gas overpressure may occur inside the battery cell. With the increase of internal pressure, it can lead to swelling of the battery cell, activation of safety mechanisms or, in the worst case, breakdown of the battery cell. 
     BRIEF DESCRIPTION OF THE INVENTION 
     An object of the present invention is to solve the above-mentioned problems and to provide a novel and innovative solution for thermal management of battery cells and battery cell assemblies. 
     The object of the invention is achieved by a technical solution in accordance with claim  1  in which the battery lid is formed of a body which encloses a flow channel which flow channel is provided with at least one flow inlet and at least one flow outlet, and wherein said flow inlet and flow outlet are arranged in flow communication with said flow channel. Other preferred embodiments of the invention are presented in the dependent claims. 
     One of the advantages of the present invention is a more even distribution of thermal energy, heat, in the battery lid between the battery terminals, and better heat transfer is provided through the surfaces and body of the battery lid than in the known solutions. By means of the invention, the individual battery cells can be cooled or heated more efficiently. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following the invention is described in detail with reference to the accompanying drawings, in which 
         FIG.  1    is a perspective view of a battery lid according to an embodiment of the invention, 
         FIG.  2    is a side view of an embodiment of the invention shown in  FIG.  1   , 
         FIG.  3    is a bottom view of an embodiment of the invention shown in  FIG.  1   , 
         FIG.  4    is a top view of an embodiment of the invention shown in  FIG.  1   , 
         FIG.  5    is a cross-sectional view of an embodiment of the invention shown in  FIG.  4    along the line B-B, 
         FIG.  6    is a cross-sectional view of an embodiment of the invention shown in  FIG.  4    along the line A-A. 
         FIG.  7    is a cross-sectional view of an embodiment of the invention shown in  FIG.  2    along the line C-C, 
         FIG.  8 A  is an exploded view of a battery cell assembly according to an embodiment of the invention, 
         FIG.  8 B  is a perspective view of a battery cell assembly according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG.  1    shows a perspective view of a battery lid according to an embodiment of the present invention. The battery lid  100 , as shown in  FIG.  1   , is designed, and adapted to be mounted in a battery cell housing (not shown in  FIG.  1   ) to cover the opening therein. Said battery cell housing may be a separate part which may enclose a battery cell, and it protects the battery cell from the outside. The battery lid  100  is advantageously dimensioned according to the dimensions of the battery cell housing so that the battery lid  100  abuts its side edges tightly against the side edges of the battery cell housing, whereby the battery lid  100  and the battery cell housing can be fastened to each other, for example by welding. The side edges of the battery lid may have chamfers that make it easier to weld and attach the battery lid to the battery cell housing, i.e. to form a battery cell assembly. 
     In  FIG.  1   , the battery lid  100  is formed of a rectangular elongate body having an upper side and a lower side, and a plurality of side edges extending therebetween, said body enclosing a flow channel (not shown in  FIG.  1   ) to be filled with a (heat transfer) fluid, and at least one flow inlet  111  and at least one flow outlet  112  to transfer said fluid. Although the body, as described herein, has a rectangular shape, other shapes may be possible, for example, circular and oval. The battery lid is provided with two terminals, a first terminal  121  (positive terminal) for a positive electrode, a cathode, and a second terminal  122  (negative terminal) for a negative electrode, an anode. The terminals  121 ,  122  are arranged to cover said electrodes when the battery cell is mounted in the battery cell housing and the battery lid is installed over said battery cell housing. Said terminals  121 ,  122  are arranged at opposite ends of the battery lid at a distance from each other. The battery lid may be electrically conductive, with at least one of the terminals being integrated into the battery lid and formed during the battery lid manufacturing process. At least one of the terminals is detachable and insulated from the battery lid. 
       FIG.  2    is a side view of an embodiment of the invention shown in  FIG.  1   . The battery lid  100 , on its upper side, which is the side away from the battery cell to be covered, has a flow inlet  111  and a flow outlet  112  which are parallel and located in the central region of the battery lid  100 , and between said terminals  121 ,  122 . The flow inlet and a flow outlet are perpendicular to the planar surface of the upper side of the battery lid. The battery lid  100 , on its lower side, which is the side facing the battery cell to be covered (opposite the upper side), has a plurality of heat transfer fins  130 , to allow improved heat transfer between the lower side and the upper side of the battery lid. Said heat transfer fins  130  extends along the planar surface of the lower side of the battery lid  100 . They  130  are preferably located in and limited to the central region which is at a distance from the plurality of side edges of the battery lids. The surrounding regions, on the lower side of the battery lid, which extends from the side edges of the battery lid  100  towards the central region are without heat transfer fins  130 . 
     It should be noted herein that the shape and configuration of the fins  130  need to be shaped according to the specifications of the battery cell and the battery cell housing. The fins  130  can thus be assumed to follow the shape of the battery cell jelly roll. Because the position and configuration of the jelly roll may vary depending on the structure of the battery cell, the design and configuration of the fins  130  on the battery lid may also vary accordingly. The purpose of the fins is to exchange heat in a three-dimensional shape on the lower side of the battery lid  100 . 
       FIG.  3    is a bottom view of the battery lid shown in  FIG.  1   . The battery lid  100 , on its lower side, has a plurality of parallel and spaced-apart heat transfer fins  130 , to transfer heat received by them, which extend along the surface of the lower side between the first terminal  121  and the second terminal  122 . Said plurality of heat transfer fins  130  are arranged in the central region and spaced from the plurality of side edges of the battery lid  100 . 
       FIG.  4    is a top view of an embodiment of the invention shown in  FIG.  1   . The battery lid  100 , on its upper side, has a first terminal  121 , having a rectangular form and embedded in the planar surface of the battery lid  100 , and a second terminal  122 , which is rectangular and protrudes from the planar surface of battery lid  100 . Said terminals  121 ,  122  are located at opposite ends of the battery lid and spaced from the plurality of side edges of the battery lid and surrounded by the planar surface of the battery lid. A shape other than rectangular may also be possible for the shape of the terminal, for example circular. Between said terminals  121 ,  122  there is a flow inlet  111  and a flow outlet  112 , and between the flow inlet and the flow outlet there is a pressure vent  140  being integrated to the battery lid. The battery lid is further provided with a fill port  150 . The fill port  150  has an opening extending into the flow channel (not shown in  FIG.  4   ) inside the battery lid  100 . The fill port  150  can further be provided with a self-tapping screw or, for example, a washer that covers the opening of the fill port as needed. 
       FIG.  5    is a cross-sectional view of an embodiment of the invention shown in  FIG.  4    along the line B-B. The first terminal  121  is provided with a through hole between the upper side and the lower side of the battery lid  100 . The fill port  150 , having a through hole opening therein, is arranged between the first terminal  121  and the pressure vent  140 . The pressure vent  140 , on the upper side of the battery lid  100 , is arranged between the flow inlet and flow outlet, and is formed of the same material than the battery lid. The pressure vent  140  has a predetermined breaking region of a reduced material thickness. The material thickness in the breaking region is preferably less than in the surrounding region, thereby allowing the breaking region to rupture at a predetermined pressure threshold with the increase of internal pressure of the battery cell housing to be covered by the battery lid. 
       FIG.  6    is a cross-sectional view of an embodiment of the invention shown in  FIG.  4    along the line A-A. The battery lid  100  is formed of an elongated body having an planar upper side and a planar lower side, and a plurality of side edges that extend upwardly between the upper side and the lower side, thereby enclosing a flow channel  160  therebetween. The flow channel  160  is arranged such that it extends continuously between the first terminal  121  and second terminal  122  around. The battery lid, on the upper side, has a flow inlet  111  and a flow outlet  112 , each  111 ,  112  having at least one vertical flow conduct portion and at least one horizontal flow conduct portion through which the flow inlet and flow outlet are in fluid communication with said flow channel  160 . 
       FIG.  7    is a cross-sectional view of an embodiment of the invention shown in  FIG.  2    along the line C-C. The flow channel  160  extends inside the battery lid  100  between a plurality of side edges and is divided into two halves by a partition wall  180  having both terminals  121 ,  122 , a pressure vent  140 , and a fill port  150  arranged therein. The flow channel  160  is shaped to surround both terminals  121 ,  122 . The partition wall  180  that insulates both terminals  121 ,  122  from the flow channel in an airtight and watertight manner forms an island within the flow channel  160 . The terminals  121 ,  122  are electrically and hermetically separated from the flow channel. Both halves of the flow channel  160  have a variable flow channel width along the length of the battery lid  100 . 
       FIGS.  8 A and  8 B  illustrate a battery cell assembly  200  which comprises a battery lid  100  and a battery cell housing  210 . The battery cell assembly  200  may also comprise a battery cell (not shown in  FIGS.  8 A and  8 B ) which may be arranged inside the battery cell housing  210 .  FIG.  8 A  shows a situation in which the battery lid  100  is spaced from the battery cell housing  210  above the opening  220  therein. In this example, the battery cell housing  210  is formed of a rectangular and upwardly opening container having a bottom and a plurality of side walls  230  extending perpendicularly upward from the edges of the bottom so that the side walls and bottom define a space for a battery cell. 
     When the battery lid  100  is installed, the lower side of the battery lid  100  with a plurality of fins  130  faces the opening  220  of the battery cell housing  210 . The battery lid  100  is mounted in the battery cell housing  210  so that the plurality of fins  130  on the battery lid  100  protrude into the inside of the battery cell housing. The side edges of the battery lid  100  protrude against the edges of the opening  220  in the battery cell housing  210 , and when installed, the side walls  230  of the battery cell housing  210  enclose the fins  130  in the battery lid. When installed in place above the opening  220 , the battery lid  100  completely covers the opening of the battery cell housing. 
     The battery lid  100  is preferably dimensioned according to the size of the battery cell housing to which it is installed so that the battery lid  100  protrudes tightly from its side edges against the side edges of the battery cell housing. This makes it easier to attach the battery lid  100  and the battery cell housing, for example by welding. When installed, small chamfers  240  on the side edges of the battery lid, on the lower side of it, facilitate welding and attachment of the battery lid to the battery cell housing, and allow the interface between the battery cell housing and the battery lid to be sealed. 
     The battery lid according to an embodiment of the present invention may be manufactured by additive manufacturing. It reduces time to get a product, i.e. the battery lid, and emancipate many constraints that are not possible with conventional production methods, such extrusion or injection molding. For example, with additive manufacturing, it is possible to print complex geometric shapes of the battery lid, such as thermal fins, and to create a single-piece battery lid, and interlocking parts for the battery lid that require no assembly, if the battery lid is manufactured from separate parts. It is also possible to produce single objects, in small quantities, at low cost and fast delivery. Additive manufacturing also helps in the reduction of production-related material loss. Additive manufacturing may also produce different objects without creating specific tooling or even using several tools. Additive manufacturing helps increasing flexibility in the production flow and helps reducing industrial expenses. Since there is no need to build a dedicated production line, it helps also to significantly save time: additive manufacturing enables to innovate faster and mechanize faster. 
     Although the battery lid  100  is designed to be manufactured by an additive manufacturing method, it may be possible to manufacture the battery lid also by other manufacturing methods, for example, an injection molding method, an extrusion method, or die casting, or any combination thereof. The materials from which the battery lid may be manufactured are not limited only to those that are suitable for the additive manufacturing. The battery lid may also be made of other materials which are suitable for the manufacturing process used, such as plastic or metals, for example copper or aluminum, or, for example, carbon-based materials, such as graphite or pyrolytic graphite, or any combination thereof. 
     The battery lid, as described above, can be implemented in many alternative ways. For example, the shape of the battery lid can be designed in a different shape than the rectangle. In addition, the said fins on the battery lid can also be configured in many alternative ways. For example, said fins may extend through the lower side of the battery lid to the inner side of the battery lid, inside the flow channel, which may further increase the heat transfer surface area and enhance heat transfer characteristics of said battery lid. For example, the orientation of the fins relative to the battery lid and their dimensions may be implemented in different ways, other than those set forth above, which are technically feasible to a person skilled in the art. 
     It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.