Patent Publication Number: US-2022238966-A1

Title: A battery assmebly

Description:
TECHNICAL FIELD 
     The present invention relates to a battery assembly. 
     BACKGROUND 
     The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge. 
     Battery clamshells are a type of battery assembly commonly used in electric vehicles. The clamshell includes batteries with welded tabs at top and bottom. Plastic layers are provided to hold the batteries and a serpentine cooling system runs though the clamshell. 
     The preferred embodiment provides a less complex battery assembly which is cost effective to produce, requiring simpler tooling, lesser assembly operations and fewer parts. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, there is provided a battery pack including: 
     batteries; 
     a first current collector for engaging with first electrodes of the batteries; 
     a second current collector for engaging with second electrodes of the batteries; and 
     fastening means for fastening the current collectors together. 
     Advantageously, the battery pack may be assembled by snap fitting the current collectors together, without the need for screws or other threaded fasteners. Preferably, the current collectors are snap fastened together in electrical connection with the batteries located there-between. 
     The fastening means may optionally be a snap fastening means, or alternatively include a slide, latch, or even thermalplast. The snap fastening means may include one or more posts extending between the current collectors. The posts may extend between gaps formed by adjoining batteries. Each post may include a resilient head for squeezably inserting through a current collector. The head may include a tapered apex to facilitate insertion. The head may be split. Each post may fixedly extend from the other current collector, preferably being integrally formed with the other current collector. The snap fastening means may be releasable. The snap fastening means may include one or more male and female parts. 
     Each current collector may include graphene. Each current collector may include an inner layer; and an outer layer adjacent the inner layer. Each current collector may include a polymeric material, thereby avoiding metal to metal welding operations thus representing a large cost savings during assembly and permitting an easier battery replacement process. 
     The inner layer may be electrically conductive and engage with the electrodes. The inner layer may be thermally conductive. The inner layer may include any one or more of polymeric material, graphene, metal powder, nickel and/or copper. 
     The outer layer may be formed of non-electrically conductive material. 
     According to another aspect of the present invention, there is provided a battery pack housing including: 
     a first current collector for engaging with first electrodes of batteries; 
     a second current collector for engaging with second electrodes of the batteries; and 
     fastening means for fastening the current collectors together. 
     According to another aspect of the present invention, there is provided a current collector for a battery pack housing, the current collector including graphene. 
     According to another aspect of the present invention, there is provided a method for assembling a battery pack, the method including: 
     fastening a first current collector for engaging with first electrodes of the batteries to a second current collector for engaging with second electrodes of the batteries. 
     The method may involve forming each current collector. The step of forming may involve joining an inner layer and an outer layer. The method of forming the inner layer may involve initially forming a solid panel, and then bonding a liquid to the solid panel which advantageously increases electrical conductivity. 
     According to one aspect of the present disclosure, there is provided a battery assembly including: 
     batteries including cases forming first electrodes; and 
     an electrically and thermally conductive current collector which is used to connect to second electrodes of the batteries and to a heatsink or thermal block. 
     Advantageously, the assembly of the preferred embodiment is less complex than clamshells requiring fewer parts, and not needing a serpentine cooling system. 
     Preferably, the current collector includes graphene. The current collector may include polymeric material. The current collector may have a thermal conductivity more than 3000 W/mK. The current collector may have an electrical conductivity of more than 100% International Annealed Copper Standard (IACS). 
     The assembly may include a linear array of batteries. The batteries may be electrically connected in parallel. The current collector may include a sheet extending adjacent the array. 
     The current collector may include a support for supporting the batteries. The support may include at least one foot. The current collector may include one or more arms coupled to the second electrodes. The current collector may be adhered to the second electrodes with adhesive. The adhesive may include graphene. The current collector may be integrally formed. 
     The assembly may include a cooler for thermally coupling to the support. The cooling assembly may include a block or plate incorporating liquid or thermoelectric cooling. 
     Each case may engage or be electrically coupled with an adjacent case to form an electrical connection. 
     The first electrode may be a negative electrode whereas the second electrode may be a positive electrode. Each battery may include a dry cell battery. 
     The assembly may be used in an electric vehicle. The assembly may be used in stationary energy storage systems. The assembly may be used in manned or unmanned aircraft. The assembly may further include connection tabs to facilitate connection to a current collector. 
     According to another aspect of the present disclosure, there is provided a battery block including connected battery assemblies. The battery assemblies may be electrically connected in series. The battery assemblies may be adhered together with adhesive. The adhesive may include graphene. The block may include current collectors separating rows of batteries. 
     According to another aspect of the present disclosure, there is provided a battery assembly including: 
     a battery including a first electrode; and 
     an electrically and thermally conductive current collector forming a second electrode of the battery. 
     Optionally, at least one heatsink is attached to the current collector through a layer of electrically insulating thermal interface material. 
     According to another aspect of the present invention, there is provided a battery assembly including: 
     one or more batteries; and 
     a heatsink which is used to sink heat from the batteries. 
     The heatsink may include one or more conduits for conveying fluid. The conduits may be aligned with respective batteries. The heatsink may include a receptacle for receiving the batteries. The conduits and receptacle may be integrally formed (e.g. molded). The receptacle may be an electrical insulator, although is thermally conductive. The heatsink may include a pair of electrically conductive terminals for engaging with respective electrodes of the batteries. The terminals may be embedded in the receptacle. The heatsink may be a clamp. 
     Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows: 
         FIG. 1  shows front and rear perspective views of an electric vehicle battery assembly; 
         FIG. 2  shows perspective views of battery blocks including the battery assembly of  FIG. 1 ; 
         FIG. 3  shows an exploded side view of an electric vehicle battery pack in accordance with an embodiment of the present invention; 
         FIG. 4  shows a plan view of the top of a housing segment of the battery pack of  FIG. 3  showing the fastening means; and 
         FIG. 5  shows the fastened segment of the battery pack of  FIG. 4 ; and 
         FIG. 6  shows a rear perspective views of an electric vehicle battery assembly in accordance with another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     There is provided an electric vehicle battery assembly  100  as shown in  FIG. 1 . The assembly  100  includes lithium ion cylindrical cells  102  with outer cylindrical cases  104  that form negative (first) electrodes. Each case  104  may engage or be electrically coupled with a current collector  106  to form an electrical connection. 
     The assembly  100  further includes an electrically and thermally conductive current collector  106  interconnecting positive (second) electrodes running along the centre of the batteries  102 . The heatsink  106  includes graphene and polymeric material engineered to meet or exceed the performance of copper or equivalent materials. 
     Advantageously, the assembly  100  is less complex than clamshells requiring fewer parts, and does not need a serpentine cooling system owing to superior thermal conductivity of the current collector  106 . 
     The assembly  100  includes a linear array of electrically parallel batteries  102 , and the positive heatsink  106  is electrically isolated from the negative cases  104 . The current collector  106  is lined with an electrically insulating backing sheet  108  extending adjacent the array of batteries  102  to isolate the negative case from the current collector  106 . 
     The integrally formed heatsink  106  may also include a foot which extends perpendicular to the main connective surface for the purpose of attaching a cooling plate or secondary heatsink (not shown). The foot acts as the thermal bridge between the passively cooled module  100  and the actively cooled secondary heatsink which typically takes the form of an external block. The actively cooled block can be integrated into the foot. The upper end of the heatsink  106  includes arms  112  with terminals for coupling to respective positive electrodes of the batteries  102 . The arms  112  may be electrically conductively adhered to the positive electrodes with adhesive including graphene. 
     The assembly  100  also includes a base cooler (not shown) for thermally coupling to the foot support  110 . The cooler may include a block or plate incorporating liquid or thermoelectric cooling systems. 
       FIG. 2  shows a battery block  200  including electrically inter-connected battery assemblies  100 . The battery assemblies  100  are adhered together in electrical series with an electrically conductive adhesive including graphene. In this manner, the heatsink  106  of one assembly  100  is adhered to the cases  104  of the next assembly  100 . The heatsinks  106  are disposed in an alternating manner and separate rows of batteries  102 . 
     The front and rear assemblies  100  in the block  200  further include connection tabs (not shown) to facilitate connection to a current collector. The block  200  is typically overmolded with an insulator  202  leaving the connection tabs exposed. 
     The modular block  200  and module assembly  100  provide approximately 15% energy/unit mass improvement (From 160 Wh/kg to &gt;220 Wh/kg) and approximately 25% volumetric energy density gain over known batteries. In addition, the block  200  and assembly  100  provide considerable cost saving of up to 20% when compared with known prismatic modules. 
       FIG. 3  shows an electric vehicle battery pack  300 . The battery pack  300  includes a two-dimensional array of batteries  302 . A lower current collector  304   a  is provided for engaging with negative (first) electrodes of the batteries  302 . The battery pack  300  also includes an upper current collector  304   b  for engaging with positive (second) electrodes of the batteries  302 . 
     As can best be seen in  FIG. 4 , snap fastening means  400  is provided for snap fastening the current collectors  304   a ,  304   b  together in electrical connection with the batteries  302  in between. Advantageously, the battery pack  300  is assembled by snap fitting the current collectors  304  together, without the need for screws or other threaded fasteners. 
     Returning to  FIG. 3 , each current collector  304  includes an inner layer  306 ; and an outer layer  308  adjacent the inner layer  306 . 
     The inner layer  306  is electrically conductive and engages with the battery electrodes. The inner layer  306  is also thermally conductive. In particular, the inner layer  306  includes a polymeric base material with added graphene and metal powder such as nickel and/or copper. 
     The outer layer  308  is formed of non-electrically conductive material (i.e. and insulator). The outer layer  308  increases strength in the casing parts, without adding size or weight, with additives including graphene into a polymer. The outer layer  308  improves thermal dissipation away from the battery cell terminals without affecting the electrical current collection. 
     Turning to  FIG. 4 , the snap fastening means  400  includes posts  402  extending between the current collectors  304 . The posts  402  extend between gaps formed by adjoining batteries  302  in the array. Each post  402  includes a resilient head  404  for squeezably inserting through a hole  406  in the upper current collector  304   b . The head  404  includes a tapered apex to facilitate insertion in the hole  406 , and is split. so that the two head halves come together when passing through the hole  406  before separating again on the other side. 
     Each post  402  fixedly extends from the lower current collector  304   a , and is integrally formed (i.e. molded) with the lower current collector  304   a . Accordingly, the battery pack housing includes only two parts. The underside of the head  404  stops inadvertent separation of the current collectors  304 . However, the snap fastening means  400  is releasable whereby a tool can be used to compress the head  404  to purposively withdraw it from the hole  406 . The top plate  304   b  can be removed without affecting the structural integrity of the top plate  304   b  or bottom plate  304   a  with the use of a separate part which when assembled to the top plate  304   a  squeezes the top of the “male” parts  404  to allow the top plate  304   b  to be removed. 
     The battery pack  300  combines the functions of several existing battery casing parts into one, reduces development time, reduces cost, improves performance of the battery, eliminates the necessity for weldable tabs in electric vehicle battery packs, and eliminates several assembly processes. 
     The battery pack  300  design provides up to 5 securing points around each battery cell, eliminates the requirement for external fasteners, allows for the reuse of parts at the end of the battery cell&#39;s life, allows for battery pack repair without damaging casing parts, eliminates several assembly processes, increases safety to for assembly staff during assembly, and increases the overall safety of the battery module  300 . 
     A method for assembling the battery pack  300  is briefly described. 
     The method involves forming each like current collector  304  by joining the inner layer  306  and the outer layer  308 . The inner layer  306  is formed by initially forming a solid panel, and then bonding a liquid to the solid panel which advantageously increases electrical conductivity. 
     The method then involves snap fastening the lower current collector  304   a  engaging with negative electrodes of the batteries  302  to the upper current collector  304   b  engaging with positive electrodes of the batteries  302  using the fastening means  400 . 
       FIG. 5  shows the assembled battery pack  300 , with the grey box  500  representing the overall size of the battery pack  300 . 
       FIG. 6  shows another battery assembly  100 ′ similar to the assembly  100  of  FIG. 1 . 
     The assembly  100 ′ includes batteries  102  with outer cylindrical cases  104 . Further, the assembly  100 ′ includes a heatsink  106 ′ which is used to sink heat from the batteries  102 . 
     The heatsink  106 ′ includes a C-shaped receptacle  600  for receiving the batteries  102 , and which is away from the centre or shaft of the battery cell  102  and out closer to the cell tabs where they are hottest. The heatsink  106 ′ further includes tubular conduits  602  extending around the outside of the C-shaped receptacle  600  and for conveying cooling fluid  604 . The conduits  602  are aligned with respective batteries  102 . 
     The conduits  602  and receptacle  600  are integrally formed, being injection molded from polymeric material which is an electrical insulator, although is thermally conductive. The conduits  602  and receptacle  600  contribute to a structurally robust heatsink  106 ′. 
     The heatsink  106 ′ further includes a pair of electrically conductive metal terminals  604   a ,  604   b  for engaging with respective electrodes of the batteries  102  at opposite ends. The terminals  604  are press embedded in the resilient receptacle  600 , and can have protrusions to facilitate engagement with respective battery electrodes. The heatsink  106 ′ forms a clamp for clamping the batteries  102 , and no screws or other fastening devices are required. This reduces the cost, complexity and number of parts. 
     A person skilled in the art will appreciate that many embodiments and variations can be made without departing from the ambit of the present invention. 
     The skilled person will understand that the battery block can be readily made to any width or depth. 
     The heatsink  106  can be formed to include graphene and polymeric material by injection molding, by rolling acrylic plastic or through a 3D printing process. 
     In one embodiment, the snap fastening means may be substituted by a slide, latch, or even thermalplast. The fastening means may include a sliding, compressive, expansive, metallic, adhesive or deformative fastener. 
     In one embodiment, the current collector  304  is formed to spring and lock onto a post that is not split. 
     In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. 
     Reference throughout this specification to ‘one embodiment’ or ‘an embodiment’ means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases ‘in one embodiment’ or ‘in an embodiment’ in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.