Patent Application
20190280354
This disclosure relates generally to packaging battery cells, and in particular, to structures for containing individual packaged battery cells.
Over time, energy density in batteries has increased, while packaging size for the batteries has decreased. Lithium ion batteries are an example of high energy density batteries and have become the preferred battery technology for items such as, consumer electronics, electric vehicles, battery backup systems, and other energetic systems requiring a mobile and rechargeable power source. A byproduct of high energy density is that lithium ion batteries pose a greater safety risk than lower energy density technologies, due to the amount of chemical energy stored in a small package. A mechanism by which high energy density batteries fail energetically is called thermal runaway, a condition where the chemical reaction inside a single cell becomes unstable due to excessive heat which may be generated by an internal defect or by other means. Thermal runaway causes the single cell to continue to heat up at an ever-accelerating rate until the structural integrity of the single cell is compromised or the single cell combusts.
One aspect of an embodiment of the present invention discloses an apparatus for containing packaged battery cells, the apparatus comprising a containment structure disposed on a printed circuit board for encasing a first battery cell, the first battery cell being electrically coupled to the printed circuit board, the containment structure being a first blast plate structure coupled a first blast tube structure. The apparatus includes the first blast tube structure partially surrounding the first battery cell, wherein a bottom surface of a first end of the first blast tube structure is coupled to a top portion of the printed circuit board. The apparatus further includes the first blast plate structure coupled to a top surface of a second end of the first blast tube structure. The apparatus further includes a first thermal interface material at least partially surrounding the first battery cell, wherein the first thermal interface material is located between the first battery cell and the first blast tube structure.
The following detailed description, given by way of example and not intended to limit the disclosure solely thereto, will best be appreciated in conjunction with the accompanying drawings, in which:
Larger battery cell packages containing multiple battery cells are typically cooled utilizing liquid coolant, where the coolant flows through tubing and piping around the battery cells to cool the battery cell package. The coolant draws heat away from the battery cells and allows for a containment unit to be placed around the cells to prevent a thermal runaway event from escaping the confines of the battery cell package. Some larger battery cell packages separate the battery cells into smaller clusters or modules which are isolated, preventing a cascading failure of all the battery cells in the battery cell package. It is atypical to provide cooling to larger battery cell packages utilizing air flow due to the difficulty of containing battery cells. The containment of battery cells prevents an uncontrolled event (e.g., fire) from exiting the battery cell package and causing damage or injury. The containment of a single battery cell prevents a single battery cell thermal runaway event from propagating to surrounding battery cells and creating a thermal runaway event across all the battery cells within the battery cell package.
Embodiments of the present invention provide an apparatus for cooling and containing battery cells in a battery cell package, while utilizing accelerated airflow as a primary cooling method. Each battery cell includes an individual blast tube structure, where the blast tube structure is made of a thermally conductive and mechanically durable material (e.g., aluminum and/or ceramic). The blast tube structure encases a single battery cell to contain a possible thermal event (e.g., fire and/or combustion) to the single battery cell, preventing the thermal event from propagating to surrounding battery cells within the battery cell package. Each blast tube structure is coupled at one end to a printed circuit board forming an array of blast tube structures, allowing for the battery cells encase in each blast tube structure to be electrically coupled to one another and to the rest of the battery package system.
A blast plate structure is coupled to the array of blast tube structures to contain a thermal event in the positive y-axis direction. A secondary blast plate structure can be coupled to a bottom surface of the printed circuit board, where a void is present between the bottom surface of the printed circuit board and the secondary blast plate structure. The void allows for the placement of electrical components on the bottom surface of the printed circuit board and the void allows for pressure relief for the battery cells through apertures in the printed circuit board. Each blast tube structure has a dedicated aperture in the printed circuit board to allow for gas to flow out through the battery cell during a high-pressure event, through the aperture in the printed circuit board, and out into the void between the printed circuit board and the secondary blast plate.
A method for manufacturing a battery cell with a blast tube structure includes electrically coupling two leads to the battery cell. A shorter lead is electrically coupled to a bottom surface of an end of the battery cell and electrically coupled to the printed circuit board. A longer lead is electrically coupled to a top surface of another end of the battery cell, where the longer lead spans the length of the battery cell and electrically couples to the printed circuit board. Electrically insulating shrink tubing is wrapped around the battery cell to cover the longer lead spanning the length of the battery cell. Subsequently, the battery cell is wrapped or coated in thermal interface material to enhance thermal coupling between the electrically insulating shrink tubing and the blast tube structure. The blast tube structure is placed around the battery cell and secured utilizing seam welding or other securing methods known in the art. The battery cell with the blast tube structure is secured to the printed circuit board utilizing a heat resistance adhesive along a lower surface of the blast tube structure that couples to a top surface of the printed circuit board. A blast plate structure is secured to the blast tube structure utilizing the heat resistance adhesive along an upper surface of the blast tube structure that is coupled to a lower surface of the blast plate structure.
As one or more fans accelerate air towards the array of blast tube structures, the accelerated air contacts the exterior surface of each blast tube structure and cools the blast tube structure with the battery cell encased within. Since the battery cell is thermally coupled to the blast tube structure via the thermal interface material, heat can transfer from the battery cell to the exterior surface of the blast tube structure. The array of blast tubes with encased battery cells are simultaneously contained and cooled utilizing the accelerated air cooling method.
Detailed embodiments of the present invention are disclosed herein with reference to the accompanying drawings; however, it is to be understood that the disclosed embodiments are merely illustrative of potential embodiments of the invention and may take various forms. In addition, each of the examples given in connection with the various embodiments is also intended to be illustrative, and not restrictive. This description is intended to be interpreted merely as a representative basis for teaching one skilled in the art to variously employ the various aspects of the present disclosure. In the description, details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the presented embodiments.
For purposes of the description hereinafter, terms such as “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, and derivatives thereof shall relate to the disclosed structures and methods, as oriented in the drawing figures. Terms such as “above”, “overlying”, “atop”, “on top”, “positioned on” or “positioned atop” mean that a first element, such as a first structure, is present on a second element, such as a second structure, wherein intervening elements, such as an interface structure may be present between the first element and the second element. The term “direct contact” means that a first element, such as a first structure, and a second element, such as a second structure, are connected without any intermediary conducting, insulating or semiconductor layers at the interface of the two elements. The term substantially, or substantially similar, refer to instances in which the difference in length, height, or orientation convey no practical difference between the definite recitation (e.g. the phrase sans the substantially similar term), and the substantially similar variations. In one embodiment, substantial (and its derivatives) denote a difference by a generally accepted engineering or manufacturing tolerance for similar devices, up to, for example, 10% deviation in value or 10° deviation in angle.
In the interest of not obscuring the presentation of embodiments of the present invention, in the following detailed description, some processing steps or operations that are known in the art may have been combined together for presentation and for illustration purposes and in some instances may have not been described in detail. In other instances, some processing steps or operations that are known in the art may not be described at all. It should be understood that the following description is rather focused on the distinctive features or elements of various embodiments of the present invention.
Many common fabrication techniques involve securing two objects using an adhesive layer between the objects. Often times the adhesive layer is chosen in an attempt to permanently secure the two objects together. And while this adhesive layer selection may be advantageous for typical usage of the overall product, there may be instances where separation of the joined objects is either desired, or necessary. In such instances, separation of the two objects, without physically damaging either of the objects, may be required so that one or both of the objects may be reused.
In another embodiment, a secondary blast plate is coupled to a bottom surface of the PCB 106, where a void is present between the bottom surface of PCB 106 and the secondary blast plate structure. The void allows for the placement of electrical components on the bottom surface of PCB 106 and the void allows for pressure relief for the battery cells through one or more apertures in PCB 106. Each battery cell tube 104 includes one or more dedicated apertures in PCB 106 to allow for gas to flow out through the battery cell during a high-pressure event, through the one or more apertures in PCB 106, and out into the void between PCB 106 and the secondary blast plate. In yet another embodiment, each battery cell tube 104 includes one or more dedicated apertures in blast plate 102 to allow for gas to flow out through the battery cell during a high-pressure event, through the one or more apertures in blast plate 102, and away from the surrounding battery cell tubes 104.
For illustration purposes,
In this embodiment, insulation cap 202 is situated below an upper surrounding edge of blast tube 204, leaving a medium for insulation cap 202 to expand during various heat cycles. Alternatively, insulation cap 202 can extended above an upper surrounding edge of blast tube 204, where coupling blast plate 102 to the upper surrounding edge of blast tube 204 compresses insulation cap 202. The upper surrounding edge of blast tube 204 creates a seal between individual battery cell tube 300 and blast plate 102, where a heat resistant adhesive can be applied on the circumference of the upper surrounding edge of blast tube 205 to create the seal with blast plate 102.
Alternatively, thermal sensor 604 can be coupled to the top surface of PCB 106 under bottom portion 600 of individual battery cell tube 300. Thermal sensor 604 monitors thermal variations of cell 502.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting to the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.
Having described preferred embodiments of a cooled containment compartment for package battery cells (which are intended to be illustrative and not limiting), it is noted that modifications and variations may be made by persons skilled in the art in light of the above teachings. It is therefore to be understood that changes may be made in the particular embodiments disclosed which are within the scope of the invention as outlined by the appended claims.
