IMPACT ATTENUATION FOR ENERGY STORAGE SYSTEMS

The present disclosure generally relates to a battery pack for an electric vehicle. In some implementation examples, the battery pack has an array of battery cells and a battery pack enclosure for holding the array of battery cells. The battery pack enclosure has a top surface above the array of battery cells. An impact attenuation layer can be integrated into at least a portion of the top surface of the battery pack enclosure. The impact attenuation layer has a first sub-layer and a second sub-layer. The first sub-layer has a first puncture resistance attribute and a first impact resistance attribute and the second sub-layer has a second puncture resistance attribute and a second impact resistance attribute. The first puncture resistance attribute is higher than the second, puncture resistance attribute and the first impact resistance attribute is lower than the second impact resistance attribute.

BACKGROUND

Generally described, a number of devices or components may be powered, at least in part, by an electric power source. In the context of vehicles, electric vehicles may be powered, in whole or in part, by a power source. The power source for an electric vehicle may be generally referred to as a “battery” or “battery pack,” which can represent individual battery cells, or cells, or a combination of battery modules. In some approaches, a cluster of cells can be combined or organized into individual modules and a cluster of modules can be further combined or organized as a battery pack. The power sources for electric vehicles can be installed and maintained in a battery pack configuration. Similar approaches/terminology can apply to grid storage application for collecting, storing, and distributing energy.

Electric vehicles typically require a large multiple of power, sometimes as much as a thousand times stronger than that of a typical consumer device, such as a mobile device. To achieve these power requirements, the battery packs of electric vehicles typically include a large, dense arrangement of individual cells. The composition and performance of the battery pack will depend on the characteristics of the individual battery cells, the total number of individual cells that are incorporated into the battery pack, and configurations/orientations of the cells and ancillary components into modules or the battery pack. The battery pack may represent one of the most expensive and massive assemblies in the context of most electric vehicle transportation and grid storage applications.

DETAILED DESCRIPTION

Generally described, one or more aspects of the present disclosure relate to energy storage systems including a unitary battery pack or module. In some embodiments, a unitary battery pack may be formed and used as a part of the structural support for a vehicle frame. In one aspect, the unitary battery pack can have, or be integrated with, a top surface that includes at least an impact attenuation layer. More specifically, in an illustrative embodiment, the configuration of the impact attenuation layer may include a first sub-layer and a second sub-layer. The first sub-layer and the second sub-layer may be made of different materials. The first sub-layer may have a relatively larger strength attribute or stiffness than the second sub-layer. The second sub-layer may have a relatively larger energy absorption attribute than the first sub-layer.

Traditional top surfaces associated with unitary battery packs may be made of various materials. Typically, the same materials are used for making the outer surfaces or other parts of the unitary battery packs, such as the outer sides or outer bottom surfaces. Such approaches can be deficient in that force applied to any portion of the integrated, unitary battery pack, such as a force to the top surface of the unitary battery pack is localized in nature. For example, in traditional implementations, it has been found that approximately 65% of the energy is impacted on the battery cells adjacent to a point of contact of a force while only 7% of the force may be experienced at neighboring cells Such effects generally mean that absent additional protection, portions of a unitary battery pack may be damaged during forces experienced during operation of a vehicle. Still further, other implementations of top surfaces that may be vulnerable to point of contact forces may include the additional implementation of air gaps or other intermediate layers that allows for deformation of the traditional top surface but avoiding the application of a force directly to the battery cells. The need for additional air gaps or intermediate layers, however, decreases the area available to hold an array of battery cells (e.g., individual cells). This can limit the size of the array of battery cells or the individual cells that form the battery pack. In turn, this results in a battery pack with less electric power capacity. Additionally, traditional attempts at reinforcement can result in increased weight of the vehicle or cost of manufacturing.

To address at least a portion of these deficiencies, the illustrative integrated, unitary battery pack can further include one or more characteristics or features that can be combined within the structural frame holding battery modules or an array of battery cells, generally referred to as a battery or battery pack. In one aspect, the unitary battery pack can be associated with or integrated with a top surface that includes at least an impact attenuation layer. More specifically, in an illustrative embodiment, the configuration of the impact attenuation layer includes a first sub-layer of a first material that has relatively larger strength attributes or stiffness than traditional plastic or polymer battery pack shell materials. The first impact attenuation layer may be made from, for example, steel, aluminum, alloy or other kinds of metallic material. The impact attenuation layer may also include a second sub-layer of a second material that has a relatively larger energy absorption attribute, such as various foams or plastics including but not limited to polypropylene, epoxy, polyurethane or other suitable alternatives. In some embodiments, the first sub-layer may be above the second sub-layer. In other embodiments, the second sub-layer may be above the first sub-layer. Illustratively, the first and second sub-layers, regardless of configuration, may be bonded.

Illustratively, one or more aspects of the present application can include the design or specification of thicknesses of at least the first sub-layer or the second sub-layer. For example, the thickness of individual sub-layers or other attributes may be selected based on an illustrative modeling and selection process. In some embodiments, the thickness of the first sub-layer may be 0.5 millimeter (mm), 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm and any values in between. Additionally, in some embodiments, the thickness of the second sub-layer may be 4.0 mm, 8.0 mm, 8.5 mm, 9.0 mm, 9.5 mm, 10.0 mm, 10.5 mm, 11.0 mm, 13.0 mm, 15.0 mm and any values in between. Accordingly, the thickness of the first sub-layer and the second sub-layer may be dependent based on the specification of the attributes of the impact attenuation layer, the individual attributes of the first sub-layer (e.g., specified stiffness), the individual attributes of the second sub-layer (e.g., specific energy absorption), and various combinations thereof.

In still other embodiments, the thickness of the first sub-layer may be relatively uniform throughout the entirety of the impact attenuation layer. In other embodiments, the thickness of the first sub-layer may be non-uniform, including the allocation of different thicknesses of the first sub-layer based on anticipated locations of potential forces, a modeled strength requirement or other factors. In a similar manner, the thickness of the second sub-layer may also be relatively uniform throughout the entirety of the impact attenuation layer. In other embodiments, the thickness of the second sub-layer may be non-uniform based on anticipated forces, a modeled energy absorption requirement or other factors, such as the need for acoustic dampening. Accordingly, illustrative impact attenuation layers may include combinations of uniform and non-uniform thickness of the first and second sub-layers.

One skilled in the relevant art will appreciate that the identified thicknesses of the sub-layers are illustrative in nature and should not be construed as limiting. The sub-layers may also be illustratively assembled and bonded to other components of a vehicle as disclosed herein. Further, as used herein, the term “battery pack” and the term “unitary battery pack” both refer to an energy storage system having a plurality of battery cells (e.g., an array of battery cells) and a structure (e.g., a battery pack enclosure) for enclosing or protecting the plurality of battery cells. The battery pack enclosure may have at least one of a top surface, a bottom surface or several side surfaces. For example, the battery pack enclosure may have only a top surface that is bonded with the plurality of battery cells. As another example, the battery pack enclosure may have a top surface and a bottom surface with the plurality of battery cells placed between the top surface and the bottom surface. Additionally, and optionally, the battery pack enclosure may have a top surface, a bottom surface and several side surfaces that fully surround the battery cells.

In some examples, a bottom surface of a battery pack may have attributes or properties similar to those of the top surface described in accordance with the present application. In some embodiments, the bottom surface may be formed from a honeycomb or ridged surface which is mechanically linked to cells within the battery pack. The bottom surface may be designed so that it can absorb and distribute impact energy from below the pack without allowing the impact to damage sensitive battery materials or breach the battery pack. In one embodiment, the bottom surface is made from a material that has sufficient stiffness and strength to support the battery cells and react to the aforementioned vehicle stresses, but also can deform in response to a road strike from below that would otherwise cause a break within the battery pack. In addition, the series of ridges can allow gases to escape from the battery pack should damage occur to a particular battery cell, or in the event of a runaway thermal event occurring within one or more cells of the battery pack. In other embodiments, the bottom surface may include compressible material that is deformable in response to the application of a physical force.

FIG.1Aillustrates a perspective view of a combination of a unitary battery pack200having an integrated impact attenuation layer262with a vehicle frame100in accordance with some embodiments of the present disclosure. As shown inFIG.1A, an impact attenuation layer262is integrated with a top surface260of the unitary battery pack200. The dimensions of the impact attenuation layer262can illustratively match the contours or design specifications of the integrated, unitary battery pack200, including various cutout sections and or overlapping sections that are not illustrated here. As show inFIG.1A, a top surface260of the unitary battery pack200can include ribs or other formations to assist in various additional or alternative vehicle functions, including mounting surfaces, guides, and the like. Additionally, the dimensions of the impact attenuation layer262can match the contours or design specifications of other vehicle components.

FIG.1Billustrates a top-down view of a combination of the unitary battery pack200having an integrated impact attenuation layer262with the vehicle frame100in accordance with some embodiments of the present disclosure. As illustrated inFIG.1B, the unitary battery pack200may form a portion of a floorboard of a vehicle. Additionally, in some embodiments, the unitary battery pack200is bonded to some portions of the vehicle frame100or other parts of an electric vehicle. As shown, the unitary battery pack200also has structural members222and224, which will be described later in greater detail.

FIG.2depicts an example exploded view of a unitary battery pack200having an integrated impact attenuation layer262according to some embodiments of the present disclosure. The unitary battery pack200has a top surface260, a bottom surface220and an array of battery cells240that includes a plurality of battery cells mounted between the top surface260and the bottom surface220. The bottom surface220has a structural member222and a structural member224. The structural members222and224may separate out battery cells within the array of battery cells240. In some embodiments, the structural members222and224can provide additional structural supports for the unitary battery pack200and form part of the structural support for the unitary battery pack200. In some embodiments, no structural members are present on the bottom surface220. In other embodiments, the bottom surface220may be removed or minimized as long as the top surface260is adequately bonded with the array of battery cells240. As such, the cost of manufacturing may be reduced. In still other embodiments, the array of battery cells240can be bonded with side surfaces (not shown inFIG.2) surrounding the array of battery cells240using adhesive techniques. Still further, in other embodiments, additional materials, such as potting materials, may be added to the unitary battery pack, such as for cooling functionality, and electrical isolation/insulation. As such, the bottom surface220may also be removed or minimized. As shown inFIG.2, the top surface260has an impact attenuation layer262, which will be described in detail below. Illustratively, the impact attenuation layer262is integrated with the top surface260of the unitary battery pack200.

FIG.3Adepicts an example top surface260of a unitary battery pack with an integrated impact attenuation layer262in accordance with some embodiments of the present disclosure. As illustrated, the top surface260has an impact attenuation layer262. As illustrated, the impact attenuation layer262shown inFIG.3Acovers only a portion of the top surface260. In one embodiment, the placement and surface area of the impact attenuation layer262can correspond to areas of the top surface260characterized as most likely to receive an impact force, areas that correspond to other structures of the vehicle (such as seating areas, cargo holds, etc.), or a combination thereof. In other embodiments, the impact attenuation layer262may cover the entire or most of the top surface260. Additionally, the impact attenuation layer262may be of different shapes and occupy smaller or larger area than shown inFIG.3A. Alternatively, the impact attenuation layer262may be separated into a plurality of individual impact attenuation layer components placed at different locations on the top surface260. Illustratively, the impact attenuation layer262(and components thereof) may be bonded to the top surface260, using a variety of materials and techniques.

FIG.3Billustrates a side view of a portion of a unitary battery pack having an integrated impact attenuation layer262according to some embodiments of the present disclosure. The impact attenuation layer262has a first sub-layer262A and a second sub-layer262B. As illustrated inFIG.3B, the first sub-layer262A is above the second sub-layer262B. The first sub-layer262A may illustratively be made of steel, aluminum, alloy or other combinations of metallic materials. The second sub-layer262B may be made of polypropylene, epoxy, polyurethane or other combinations of plastic or foam materials. In some embodiments, the materials used to form the first sub-layer262A and the second sub-layer262B are selected such that a puncture resistance (or a puncture resistance attribute) of the first sub-layer262A is higher or greater than a puncture resistance of the second sub-layer262B. Specifically, the first sub-layer262A has a greater ability to inhibit the intrusion of an object or force foreign to the top surface260than the second sub-layer262B. In contrast, an impact resistance (or an impact resistance attribute) of the first sub-layer262A is lower than an impact resistance of the second sub-layer262B. In other words, the second sub-layer262B has a greater ability than the first sub-layer262A to absorb shock or impact energy without fracturing or breaking.

In some embodiments, the thickness of the first sub-layer262A may be between 0.5 mm to 3.0 mm. Additionally, in some embodiments, the thickness of the second sub-layer262B may be between 4.0 mm to 15.0 mm. Although the thickness of the first sub-layer262A and the second sub-layer262B are illustratively uniform, in some embodiments, the thickness of at least one of the first sub-layer262A or the second sub-layer262B can be non-uniform. In one embodiment, the thickness of the first sub-layer262A is uniform and the thickness of the second sub-layer262B is uniform. In another embodiment, the thickness of the first sub-layer262A is non-uniform and the thickness of the second sub-layer262B is uniform. In still another embodiment, the thickness of the first sub-layer262A is uniform and the thickness of the second sub-layer262B is non-uniform. In yet another embodiment, the thickness of the first sub-layer262A is non-uniform and the thickness of the second sub-layer262B is non-uniform. In some examples, the uniformity of the thickness of the first sub-layer262A and the second sub-layer262B may be determined based on the likelihood of encountering of external impact. For example, the first sub-layer262A may be thicker in some part of the top surface260where external force is more likely to strike and may be thinner in other part of the top surface260where external force is less likely to strike. In other embodiments, there may be no impact attenuation layer262on portions of the top surface where neither foreign objects nor impact energy are likely to strike. As such, the impact attenuation layer262can be configured based on anticipated forces applied to the unitary battery pack/vehicle to protect battery cells below the top surface260at a moderate cost.

In addition to protecting a battery pack from external force or impact, the impact attenuation layer262may further provide acoustic dampening for a vehicle. In some embodiments, the material used to make the second sub-layer262B is selected such that the second sub-layer262B can retain both desired impact resistance attribute and acoustic dampening attribute. In some embodiments, an acoustic dampening attribute of the second sub-layer262B may be higher or greater than that of the first sub-layer262A. Specifically, the selection of materials and configuration of material depth of the second sub-layer262B has a greater capability of absorbing sound or noise than the first sub-layer262A. In some embodiments, the thickness of the second sub-layer262B can be varied for providing adequate level of acoustic dampening. For example, the second sub-layer262B may be thicker in area of the top surface260that is closer to source of noise, such as the area of the top surface260that is closer to the front or rear wheels of the vehicle.

As described previously, the top surface260of a unitary battery pack may form a portion of a floorboard of a vehicle (e.g., as shown inFIG.1B). Advantageously, the acoustic dampening attribute of the second sub-layer262B may allow the removal of a vehicle carpet foam that is traditionally deployed on areas the floorboard of the vehicle where acoustic dampening is desired. By removing the vehicle carpet foam, the height of the vehicle cabin will not be decreased and the cost of manufacturing can also be reduced.

As illustrated inFIGS.1A,1B,2,3A and3B, the impact attenuation layer262is shown as being integrated with a top surface260of a unitary battery pack. In other embodiments, the impact attenuation layer262may be deployed or integrated with other parts of a vehicle. For example, referring toFIG.2, the impact attenuation layer262is shown integrated with the top surface260of the unitary battery pack200. Alternatively, the impact attenuation layer262can be integrated with the bottom surface220of the unitary battery pack200. More specifically, the impact attenuation layer262can be deployed above or underneath the bottom surface220of the unitary battery pack200to protect the unitary battery pack200from external force coming from below the unitary battery pack200or from the ground. For another example, referring toFIG.1A, the impact attenuation layer262is shown integrated with the top surface260of the unitary battery pack200. Alternatively, the impact attenuation layer262can be integrated with a portion of a floorboard of the vehicle frame100.

FIGS.4A,4B and4Cdepict block diagrams representative of the components of a unitary battery pack200illustrating examples of integrating impact attenuation layers262into unitary battery packs200through cross-sectional views in accordance with some embodiments of the present disclosure. As shown inFIG.4A, the unitary battery pack200has a top surface260, an array of battery cells240that includes a plurality of individual cells241, and a bottom surface220. The impact attenuation layer262is integrated into a portion of the top surface260of the unitary battery pack200, such as by being bonded directly to the top surface260. The impact attenuation layer262has a first sub-layer262A and a second sub-layer262B. As illustrated inFIG.4A, the first sub-layer262A and the second sub-layer262B have equal and uniform thicknesses. As shown inFIG.4A, the impact attenuation layer262does not cover the entire area of the top surface260but illustratively spreads around the center of the top surface260. In some embodiments, area of the top surface260covered or not covered by the impact attenuation layer262are determined based on anticipated locations of potential forces. For example, the area261not covered by the impact attenuation layer262may be area right under the passenger seats of an electric vehicle or other area where potential forces are less likely to strike. As another example, the impact attenuation layer262may be deployed at area where passengers are likely to directly step or tread upon. Alternatively, as illustrated inFIG.4B, the impact attenuation layer262may be deployed around the edge263of the top surface260as forces external to the vehicle may impact the edge263of the top surface260more heavily. Additionally,FIG.4Cillustrates another configuration of deploying the impact attenuation layer262on the top surface260of a unitary battery pack200. In some embodiments, at least one of the first sub-layer262A or the second sub-layer262B may have a non-uniform thickness. Other various distribution of the impact attenuation layer across a top surface of a battery pack should not be construed to fall outside the scope of the present disclosure.

Generally described, the implementation of the impact attenuation layer262in the context of the battery pack200can provide a more globalized deformation such that impact forces applied to the array of battery cells240(or to a plurality of battery cells) can be more widely distributed rather than localized, in contrast to other approaches previously described. For example, it has been noted that globalized deformation attributable to the impact attenuation layer262can decrease the potential energy directed to any individual cell241in the array of battery cells240due to an applied force (such as from an external object or force striking the top surface260) by at least 65%. In some embodiments, the energy absorption attributable to the impact attenuation layer262may limit any potential forces that are applied to the array of battery cells240. This can mitigate damage or deformation on the array of battery cells240. Still further, in other aspects, the impact attenuation layer262implemented as a part of the top surface260may further absorb potential energy from an external object directed toward the battery pack200or force striking the bottom surface220of the battery pack200. In some embodiments, the energy absorption attributable to the impact attenuation layer262may limit the potential forces transferred between the array of battery cells240and the impact attenuation layer262. This can mitigate damage or deformation associated with the transference of the force (e.g., due to the physical contact of the battery cells240and the impact attenuation layer262).

FIG.5is a cutaway view of a portion of a unitary battery pack200illustrating an array of battery cells240(e.g., a plurality of battery cells) forming a portion of the battery pack200and an integrated impact attenuation layer262in accordance with embodiments of the present disclosure. Integrated onto (or within) the top surface260of the battery pack200are components (e.g., electrical conductors or busbar that are not explicitly shown) associated with the array of battery cells240. The cutaway view also illustrates a bottom surface220of the battery pack200and a vehicle floor264for the vehicle. In some embodiments, the top surface260may be integrated with the vehicle floor264.FIG.5also illustrates a first sub-layer262A and a second sub-layer262B that together form an impact attenuation layer262, which is a part of the top surface260, in accordance with one or more aspects of the present application. The first sub-layer262A may inhibit foreign objects or forces from intruding through the top surface260into the array of battery cells240. The second sub-layer may absorb external impact energy that is directed toward the array of battery cells240. As illustrated inFIG.5, the spacing between the array of battery cells240, the vehicle floor264, associated electronics/connectors and the impact attenuation layer262is illustratively minimized to achieve the spacing benefits described herein as aspects of the present application. In some embodiments, a puncture resistance (or a puncture resistance attribute) of the first sub-layer262A is higher or greater than a puncture resistance of the second sub-layer262B; and an impact resistance (or an impact resistance attribute) of the first sub-layer262A is lower than an impact resistance of the second sub-layer262B.

In one embodiment, one or more traditional components or attributes of the battery pack200may be removed or reduced based on the functionality provided by the impact attenuation layer262. More specifically, the energy absorption and dissipation properties of the impact attenuation layer262can facilitate the reduction or removal of buffering air gaps or other protective layers that exist between the array of battery cells240and the top surface260. As such, the array of battery cells240may physically contact the top surface260. Accordingly, the reduction in traditional surfaces can allow increased electric power capacity of the battery pack, such as by allowing greater dimension for the individual cells in the illustrative battery pack. Advantageously, this can result in greater power output (e.g., increased battery cell dimensions) or stored charge based on maximization of the available space in the battery compartment. In other embodiments, although not shown inFIG.5, some portion of the additional space not required for buffering or additional protective layers can be utilized to incorporate cooling areas/mechanisms, insulation mechanisms, control mechanisms, sensors or sensing systems, electrical bussing, venting structures, and the like. In addition to achieving integration, these additional components may also be protected by the energy absorption attributes of the impact attenuation layer262. In some examples, the top surface260that is associated with the impact attenuation layer262can have different attributes, such as including different materials and thicknesses.

In some embodiments, the first sub-layer262A and the second sub-layer262B may be bonded according to the desired height attributes for the impact attenuation layer262. Bonding can be achieved by suitable adhesive material or mechanism. Additionally, the impact attenuation layer262may be bonded to the other components of the vehicle, such as the vehicle floor264. Additionally, the impact attenuation layer262can further provide for acoustic dampening. In some examples, the material used for making the second sub-layer262B and the thickness of the second sub-layer262B are chosen to achieve a threshold amount of acoustic dampening attribute. For example, a thickness can be chosen for the second sub-layer262B such that the second sub-layer262B can provide a required level of acoustic dampening for a vehicle.

In the foregoing specification, the disclosure has been described with reference to specific embodiments. However, as one skilled in the art will appreciate, various embodiments disclosed herein can be modified or otherwise implemented in various other ways without departing from the spirit and scope of the disclosure. Accordingly, this description is to be considered as illustrative and is for the purpose of teaching those skilled in the art the manner of making and using various embodiments of the disclosed air vent assembly. It is to be understood that the forms of disclosure herein shown and described are to be taken as representative embodiments. Equivalent elements, materials, processes or steps may be substituted for those representatively illustrated and described herein. Moreover, certain features of the disclosure may be utilized independently of the use of other features, all as would be apparent to one skilled in the art after having the benefit of this description of the disclosure. Expressions such as “including”, “comprising”, “incorporating”, “consisting of”, “have”, “is” used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.

Further, various embodiments disclosed herein are to be taken in the illustrative and explanatory sense, and should in no way be construed as limiting of the present disclosure. All joinder references (e.g., attached, affixed, coupled, connected, and the like) are only used to aid the reader's understanding of the present disclosure, and may not create limitations, particularly as to the position, orientation, or use of the systems and/or methods disclosed herein. Therefore, joinder references, if any, are to be construed broadly. Moreover, such joinder references do not necessarily infer that two elements are directly connected to each other. Additionally, all numerical terms, such as, but not limited to, “first”, “second”, “third”, “primary”, “secondary”, “main” or any other ordinary and/or numerical terms, should also be taken only as identifiers, to assist the reader's understanding of the various elements, embodiments, variations and/or modifications of the present disclosure, and may not create any limitations, particularly as to the order, or preference, of any element, embodiment, variation and/or modification relative to, or over, another element, embodiment, variation and/or modification.