Patent Publication Number: US-2021184287-A1

Title: Vehicle energy-storage systems having parallel cooling

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 14/868,234, filed Sep. 28, 2015, which is a continuation of U.S. patent application Ser. No. 14/841,617, filed Aug. 31, 2015, which claims the benefit of U.S. Provisional Application No. 62/186,977, filed on Jun. 30, 2015. The subject matter of the aforementioned applications is incorporated herein by reference for all purposes. 
    
    
     FIELD 
     The present application relates generally to energy-storage systems, and more specifically to energy-storage systems for vehicles. 
     BACKGROUND 
     It should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section. 
     Electric-drive vehicles offer a solution for reducing the impact of fossil-fuel engines on the environment and transforming automotive mobility into a sustainable mode of transportation. Energy-storage systems are essential for electric-drive vehicles, such as hybrid electric vehicles, plug-in hybrid electric vehicles, and all-electric vehicles. However, present energy-storage systems have disadvantages including large size, inefficiency, and poor safety, to name a few. Similar to many sophisticated electrical systems, heat in automotive energy-storage systems should be carefully managed. Current thermal management schemes consume an inordinate amount of space. Present energy-storage systems also suffer from inefficiencies arising variously from imbalance among battery cells and resistance in various electrical connections. In addition, current energy-storage systems are not adequately protected from forces such as crash forces encountered during a collision. 
     SUMMARY 
     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     According to various embodiments, the present technology may be directed to vehicle energy-storage systems having parallel cooling comprising: a plurality of modules, each module comprising two half modules coupled together, each half module including: a plurality of battery cells, the battery cells being cylindrical rechargeable battery cells each having a first end and a second end, the first end distal from the second end, and having an anode terminal and a cathode terminal being disposed at the first end; a current carrier electrically coupled to the battery cells, the cathode terminal of each of the battery cells being coupled to a respective first contact of the current carrier, the anode terminal of each of the battery cells being coupled to a respective second contact of the current carrier; a plate disposed substantially parallel to the current carrier such that the battery cells are disposed between the current carrier and the plate; and an enclosure having the battery cells, current carrier, and plate disposed therein, the enclosure comprising: a coolant input port; a coolant output port; and a power connector electrically coupled to the current carrier, the enclosure having a coolant sub-system for circulating coolant flowing into the enclosure through the coolant input port and out of the enclosure through the coolant output port in parallel such that each of the battery cells is at approximately the same predetermined temperature; a tray having the plurality of modules disposed therein; and a coolant system for circulating coolant flowing into the tray across the plurality of modules and battery cells in parallel such that each of the modules is at approximately the same predetermined temperature. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements. 
         FIG. 1  illustrates an example environment in which an energy-storage system can be used. 
         FIG. 2A  shows an orientation of battery modules in an energy-storage system, according to various embodiments of the present disclosure. 
         FIG. 2B  depicts a bottom part of an enclosure of a partial battery pack such as shown in  FIG. 2A . 
         FIG. 3  is a simplified diagram illustrating coolant flows, according to example embodiments. 
         FIG. 4  is a simplified diagram of a battery module, according to various embodiments of the present disclosure. 
         FIG. 5  illustrates a half module, in accordance with various embodiments. 
         FIGS. 6A and 6B  show a current carrier, according to various embodiments. 
         FIG. 7  depicts an example battery cell. 
         FIGS. 8 and 9  illustrate further embodiments of a battery module. 
         FIGS. 10A and 10B  show battery module coupling, according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While this technology is susceptible of embodiment in many different forms, there are shown in the drawings and will herein be described in detail several specific embodiments, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the technology and is not intended to limit the technology to the embodiments illustrated. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the technology. 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. It will be further understood that the terms “comprises,” “comprising,” “includes,” and “including,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that like or analogous elements and/or components, referred to herein, may be identified throughout the drawings with like reference characters. It will be further understood that several of the figures are merely schematic representations of the present technology. As such, some of the components may have been distorted from their actual scale for pictorial clarity. 
     Some embodiments of the present invention can be deployed in a wheeled, self-powered motor vehicle used for transportation, such as hybrid electric vehicles, plug-in hybrid electric vehicles, and all-electric vehicles. For example,  FIG. 1  illustrates an electric car  100 . Electric car  100  is an automobile propelled by one or more electric motors  110 . Electric motor  110  can be coupled to one or more wheels  120  through a drivetrain (not shown in  FIG. 1 ). Electric car  100  can include a frame  130  (also known as an underbody or chassis). Frame  130  is a supporting structure of electric car  100  to which other components can be attached/mounted, such as, for example, a battery pack  140   a . Battery pack  140   a  can supply electricity to power one or more electric motors  110 , for example, through an inverter. The inverter can change direct current (DC) from battery pack  140   a  to alternating current (AC), as required for electric motors  110 , according to some embodiments. 
     As depicted in  FIG. 1 , battery pack  140   a  may have a compact “footprint” and be at least partially enclosed by frame  130  and disposed to provide a predefined separation, e.g. from structural rails  150  of an upper body that couples to frame  130 . Accordingly, at least one of a rear crumple zone  160 , a front crumple zone  170 , and a lateral crumple zone  180  can be formed around battery pack  140   a . Both the frame  130  and structural rails  150  may protect battery pack  140   a  from forces or impacts exerted from outside of electric car  100 , for example, in a collision. In contrast, other battery packs which extend past at least one of structural rails  150 , rear crumple zone  160 , and front crumple zone  170  remain vulnerable to damage and may even explode in an impact. 
     Battery pack  140   a  may have a compact “footprint” such that it may be flexibly used in and disposed on frame  130  having different dimensions. Battery pack  140   a  can also be disposed in frame  130  to help improve directional stability (e.g., yaw acceleration). For example, battery pack  140   a  can be disposed in frame  130  such that a center of gravity of electric car  100  is in front of the center of the wheelbase (e.g., bounded by a plurality of wheels  120 ). 
       FIG. 2A  shows a battery pack  140   b  with imaginary x-, y-, and z-axis superimposed, according to various embodiments. Battery pack  140   b  can include a plurality of battery modules  210 . In the non-limiting example, battery pack  140   b  can be approximately 1000 mm wide (along x-axis), 1798 mm long (along y-axis), and 152 mm high (along z-axis), and can include 36 of battery modules  210 . 
       FIG. 2B  illustrates an exemplary enclosure  200  for battery pack  140   b  having a cover removed for illustrative purposes. Enclosure  200  includes tray  260  and a plurality of battery modules  210 . The tray  260  may include a positive bus bar  220  and a negative bus bar  230 . Positive bus bar  220  can be electrically coupled to a positive (+) portion of a power connector of each battery module  210 . Negative bus bar  230  can be electrically coupled to a negative(−) portion of a power connector of each battery module  210 . Positive bus bar  220  is electrically coupled to a positive terminal  240  of enclosure  200 . Negative bus bar  230  can be electrically coupled to a negative terminal  250  of enclosure  200 . As described above with reference to  FIG. 1 , because bus bars  220  and  230  are within structural rails  150 , they can be protected from collision damage. 
     According to some embodiments, negative bus bar  230  and positive bus bar  220  are disposed along opposite edges of tray  260  to provide a predefined separation between negative bus bar  230  and positive bus bar  220 . Such separation between negative bus bar  230  and positive bus bar  220  can prevent or at least reduce the possibility of a short circuit (e.g., of battery pack  140   b ) due to a deformity caused by an impact. 
     As will be described further in more detail with reference to  FIG. 5 , battery module  210  can include at least one battery cell (details not shown in  FIG. 2A , see  FIG. 7 ). The at least one battery cell can include an anode terminal, a cathode terminal, and a cylindrical body. The battery cell can be disposed in each of battery module  210  such that a surface of the anode terminal and a surface of the cathode terminal are normal to the imaginary x-axis referenced in  FIG. 2A  (e.g., the cylindrical body of the battery cell is parallel to the imaginary x-axis). This can be referred to as an x-axis cell orientation. 
     In the event of fire and/or explosion in one or more of battery modules  210 , the battery cells can be vented along the x-axis, advantageously minimizing a danger and/or a harm to a driver, passenger, cargo, and the like, which may be disposed in electric car  100  above battery pack  140   b  (e.g., along the z-axis), in various embodiments. 
     The x-axis cell orientation of battery modules  210  in battery pack  140   b  shown in  FIGS. 2A and 2B  can be advantageous for efficient electrical and fluidic routing to each of battery module  210  in battery pack  140   b . For example, at least some of battery modules  210  can be electrically connected in a series forming string  212 , and two or more of string  212  can be electrically connected in parallel. This way, in the event one of string  212  fails, others of string  212  may not be affected, according to various embodiments. 
       FIG. 3  illustrates coolant flows and operation of a coolant system and a coolant sub-system according to various embodiments. As shown in  FIG. 3 , the x-axis cell orientation can be advantageous for routing coolant (cooling fluid) in parallel to each of battery modules  210  in battery pack  140   b . Coolant can be pumped into battery pack  140   b  at ingress  310  and pumped out of battery pack  140   b  at egress  320 . A resulting pressure gradient within battery pack  140   b  can provide sufficient circulation of coolant to minimize a temperature gradient within battery pack  140   b  (e.g., a temperature gradient within one of battery modules  210 , a temperature gradient between battery modules  210 , and/or a temperature gradient between two or more of string  212  shown in  FIG. 2A ). 
     Within battery pack  140   b , the coolant system may circulate the coolant, for example, to battery modules  210  (e.g., the circulation is indicated by reference numeral  330 ). One or more additional pumps (not shown in  FIG. 3 ) can be used to maintain a roughly constant pressure between multiple battery modules  210  connected in series (e.g., in string  212  in  FIG. 2A ) and between such strings. Within each battery module  210 , the coolant sub-system may circulate the coolant, for example, between and within two half modules  410  and  420  shown in  FIG. 4  (e.g., the circulation indicated by reference numeral  340 ). In some embodiments, the coolant can enter each battery module  210  through an interface  350  between two half modules  410  and  420 , in a direction (e.g., along the y- or z-axis) perpendicular to the cylindrical body of each battery cell, and flow to each cell. Driven by pressure within the coolant system, the coolant then can flow along the cylindrical body of each battery (e.g., along the x-axis) and may be collected at the two (opposite) side surfaces  360 A and  360 B of the module that can be normal to the x-axis. In this way, heat can be efficiently managed/dissipated and thermal gradients minimized among all battery cells in battery pack  140   b , such that a temperature may be maintained at an approximately uniform level. 
     In some embodiments, parallel cooling, as illustrated in  FIG. 3 , can maintain temperature among battery cells in battery pack  140   b  at an approximately uniform level such that a direct current internal resistance (DCIR) of each battery cell is maintained at an substantially predefined resistance. The DCIR can vary with a temperature, therefore, keeping each battery cell in battery pack  140   b  at a substantially uniform and predefined temperature can result in each battery cell having substantially the same DCIR. Since a voltage across each battery cell can be reduced as a function of its respective DCIR, each battery cell in battery pack  140   b  may experience substantially the same loss in voltage. In this way, each battery cell in battery pack  140   b  can be maintained at approximately the same capacity and imbalances between battery cells in battery pack  140   b  can be minimized. 
     In some embodiments, when compared to techniques using metal tubes to circulate coolant, parallel cooling can enable higher battery cell density within battery module  210  and higher battery module density in battery pack  140   b . In some embodiments, coolant or cooling fluid may be at least one of the following: synthetic oil, for example, poly-alpha-olefin (or poly-ex-olefin, also abbreviated as PAO) oil, ethylene glycol and water, liquid dielectric cooling based on phase change, and the like. 
       FIG. 4  illustrates battery module  210  according to various embodiments. A main power connector  460  can provide power from battery cells  450  to outside of battery module  210 . In some embodiments, battery module  210  can include two half modules  410  and  420 , each having an enclosure  430 . Enclosure  430  may be made using one or more plastics having sufficiently low thermal conductivities. Respective enclosures  430  of each of the two half modules  410  and  420  may be coupled with each other to form the housing for battery module  210 . 
       FIG. 4  includes a view  440  of enclosure  430  (e.g., with a cover removed). For each of half modules  410 ,  420  there is shown a plurality of battery cells  450  oriented (mounted) horizontally (see also  FIG. 5  and  FIG. 8 ). By way of non-limiting example, each half module includes one hundred four of battery cells  450 . By way of further non-limiting example, eight of battery cells  450  are electrically connected in a series (e.g., the staggered column of eight battery cells  450  shown in  FIG. 4 ), with a total of thirteen of such groups of eight battery cells  450  electrically connected in series. By way of additional non-limiting example, the thirteen groups (e.g., staggered columns of eight battery cells  450  electrically coupled in series) are electrically connected in parallel. This example configuration may be referred to as “8S13P” (8 series, 13 parallel). In some embodiments, the 8S13P electrical connectivity can be provided by current carrier  510 , described further below in relation to  FIGS. 5 and 6 . Other combinations and permutations of battery cells  450  electrically coupled in series and/or parallel maybe used. 
       FIG. 5  depicts a view of half modules  410 , 420  without enclosure  430  in accordance with various embodiments. Half modules  410  and  420  need not be the same, e.g., they may be mirror images of each other in some embodiments. Half modules  410  and  420  can include a plurality of battery cells  450 . The plurality of battery cells  450  can be disposed between current carrier  510  and blast plate  520  such that an exterior side of each of battery cells  450  is not in contact with the exterior sides of other (e.g., adjacent) battery cells  450 . In this way, coolant can circulate among and between battery cells  450  to provide submerged, evenly distributed cooling. In addition, to save the weight associated with coolant in areas where cooling is not needed, air pockets can be formed using channels craftily designed in the space  530  between current carrier  510  and blast plate  520  not occupied by battery cells  450 . Coolant can enter half modules  410 , 420  through coolant intake  540 , is optionally directed by one or more flow channels, circulates among and between the plurality of battery cells  450 , and exits through coolant outtake  550 . In some embodiments, coolant intake  540  and coolant outtake  550  can each be male or female fluid fittings. In some embodiments, coolant or cooling fluid is at least one of: synthetic oil such as poly-alpha-olefin (or poly-ex-olefin, abbreviated as PAO) oil, ethylene glycol and water, liquid dielectric cooling based on phase change, and the like. Compared to techniques using metal tubes to circulate coolant, submerged cooling improves a packing density of battery cells  450  (e.g., inside battery module  210  and half modules  410 ,  420 ) by 15%, in various embodiments. 
       FIGS. 6A and 6B  depict current carrier  510 ,  510 A according to various embodiments. Current carrier  510 ,  510 A is generally flat (or planar) and comprises one or more layers (not shown in  FIGS. 6A and 6B ), such as a base layer, a positive power plane, a negative power plane, and signal plane sandwiched in-between dielectric isolation layers (e.g., made of polyimide). In some embodiments, the signal plane can include signal traces and be used to provide battery module telemetry (e.g., battery cell voltage, current, state of charge, and temperature from optional sensors on current carrier  510 ) to outside of battery module  210 . 
     As depicted in  FIG. 6B , current carrier  510 A can be a magnified view of a portion of current carrier  510 , for illustrative purposes. Current carrier  510 A can be communicatively coupled to each of battery cells  450 , for example, at a separate (fused) positive (+) portion  630  and a separate negative (−) portion  640  which may be electrically coupled to the positive power plane and negative power plane (respectively) of current carrier  510 A, and to each cathode and anode (respectively) of a battery cell  450 . In some embodiments, positive(+) portion  630  can be laser welded to a cathode terminal of battery cell  450 , and negative(−) portion  640  can be laser welded to an anode terminal of battery cell  450 . In some embodiments, the laser-welded connection can have on the order of 5 milli-Ohms resistance. In contrast, electrically coupling the elements using ultrasonic bonding of aluminum bond wires can have on the order of 10 milli-Ohms resistance. Laser welding advantageously can have lower resistance for greater power efficiency and take less time to perform than ultrasonic wire bonding, which can contribute to greater performance and manufacturing efficiency. 
     Current carrier  510 A can include a fuse  650  formed from part of a metal layer (e.g., copper, aluminum, etc.) of current carrier  510 A, such as in the positive power plane. In some embodiments, the fuse  650  can be formed (e.g., laser etched) in a metal layer (e.g., positive power plane) to dimensions corresponding to a type of low-resistance resistor and acts as a sacrificial device to provide overcurrent protection. For example, in the event of thermal runaway of one of battery cell  450  (e.g., due to an internal short circuit), the fuse may “blow,” breaking the electrical connection to the battery cell  450  and electrically isolating the battery cell  450  from current carrier  510 A. Although an example of a fuse formed in the positive power plane is provided, a fuse may additionally or alternatively be a part of the negative power plane. 
     Additional thermal runaway control can be provided in various embodiments by scoring on end  740  (identified in  FIG. 7 ) of the battery cell  450 . The scoring can promote rupturing to effect venting in the event of over pressure. In various embodiments, all battery cells  450  may be oriented to allow venting into the blast plate  520  for both half modules. 
     In some embodiments, current carrier  510  can be comprised of a printed circuit board and a flexible printed circuit. For example, the printed circuit board may variously comprise at least one of copper, FR-2 (phenolic cotton paper), FR-3 (cotton paper and epoxy), FR-4 (woven glass and epoxy), FR-5 (woven glass and epoxy), FR-6 (matte glass and polyester), G-10 (woven glass and epoxy), CEM-1 (cotton paper and epoxy), CEM-2 (cotton paper and epoxy), CEM-3 (non-woven glass and epoxy), CEM-4 (woven glass and epoxy), and CEM-5 (woven glass and polyester). By way of further non-limiting example, the flexible printed circuit may comprise at least one of copper foil and a flexible polymer film, such as polyester (PET), polyimide (PI), polyethylene naphthalate (PEN), polyetherimide (PEI), along with various fluoropolymers (FEP), and copolymers. 
     In addition to electrically coupling battery cells  450  to each other (e.g., in series and/or parallel), current carrier  510  can provide electrical connectivity to outside of battery module  210 , for example, through main power connector  460  ( FIG. 4 ). Current carrier  510  may also include electrical interface  560  ( FIGS. 5, 6A ) which transports signals from the signal plane. Electrical interface  560  can include an electrical connector (not shown in  FIGS. 5, 6A ). 
       FIG. 7  shows battery cell  450  according to some embodiments. In some embodiments, battery cell  450  can be a lithium ion (Ii-ion) battery. For example, battery cell  450  may be an 18650 type Ii-ion battery having a cylindrical shape with an approximate diameter of 18.6 mm and approximate length of 65.2 mm. Other rechargeable battery form factors and chemistries can additionally or alternatively be used. In various embodiments, battery cell  450  may include can  720  (e.g., the cylindrical body), anode terminal  770 , and cathode terminal  780 . For example, anode terminal  770  can be a negative terminal of battery cell  450  and cathode terminal  780  can be a positive terminal of battery cell  450 . Anode terminal  770  and cathode terminal  780  can be electrically isolated from each other by an insulator or dielectric. 
       FIG. 8  illustrates another example of a battery module, battery module  210   b , according to various embodiments. As described in relation to battery module  210  in  FIG. 4 , battery module  210   b  may include two half modules  410  and  420  and main power connector  460 . Each of half modules  410  and  420  may include one of enclosure  430  for housing battery cells therein. Battery module  210   b  further depicts main coolant input port  820 , main coolant output port  810 , and communications and low power connector  830 . Coolant can be provided to battery module  210   b  at main coolant input port  820 , circulated within battery module  210   b , and received at main coolant output port  810 . 
     In contrast to the view of battery module  210  in  FIG. 4 ,  FIG. 8  depicts current carrier  510 . Battery module  210   b  may include one or more staking features  840  to hold current carrier  510  in battery module  210   b . For example, staking feature  840  can be a plastic stake. In some embodiments, communications and low power connector  830  can be at least partially electrically coupled to the signal plane and/or electrical interface  560  of current carrier  510 , for example, through electronics for data acquisition and/or control (not shown in  FIG. 8 ). Communications and low power connector  830  may provide low power, for example, to electronics for data acquisition and/or control, and sensors. 
       FIG. 9  shows another view of battery module  210   b  where the battery cells and the current carrier are removed from one of the half modules, for illustrative purposes. As described in relation to  FIGS. 4 and 8 , battery module  210   b  may include two half modules  410  and  420 , main power connector  460 , main coolant output port  810 , main coolant input port  820 , and communications and low power connector  830 . Each of the half modules  410  and  420  can include an enclosure  430 . Each enclosure  430  may further include plate  910  (e.g., a bracket). Plate  910  may include structures for securing the battery cells within enclosure  430  and maintaining the distance between battery cells. 
       FIGS. 10A and 10B  illustrate arrangement and coupling between two of battery modules  210   b :  2101  and  2102 . From different perspective views,  FIG. 10A  depicts battery modules  2101  and  2102  being apart and aligned for coupling. For example, battery modules  2101  and  2102  are positioned as shown in  FIG. 10A  and moved together until coupled as shown in the example in  FIG. 10B . Generally, a female receptacle on one of battery modules  2101  and  2102  may receive and hold a male connector on the other of battery modules  2102  and  2101 , respectively. 
     As shown in the example in  FIG. 10A , a left side of battery modules  2101  and  2102  may have male connectors and a right side of battery modules  2101  and  2102  have female connectors, according to some embodiments. For example, the left sides of battery modules  2101  and  2102  include male main power connector  460 M, male main coolant output port  810 M, male main coolant input port  820 M, and male communications and low power connector  830 M. By way of further non-limiting example, the right sides of battery modules  2101  and  2102  can include female main power connector  460 F, female main coolant output port  810 F, female main coolant input port  820 F, and female communications and low power connector  830 F. Each of female main power connector  460 F, female main coolant output port  810 F, female main coolant input port  820 F, and female communications and low power connector  830 F may include an (elastomer) o-ring or other seal. Other combinations and permutations of male and female connectors-such as a mix of male and female connectors on each side, and female connectors on the right side and male connectors on the left side-maybe used. 
       FIG. 10B  depicts a cross-sectional view of battery modules  2101  and  2102  of  FIG. 10A  coupled together. For example, male main power connector  460 M and female main power connector  460 F ( FIG. 10A ) can combine to form coupled main power connectors  460   c , male main coolant output port  810 M and female main coolant output port  810 F can combine to form coupled main coolant output ports  810   c , male main coolant input port  820 M and female main coolant input port  820 F can combine to form coupled main coolant input ports  820   c  (not shown in  FIG. 10B ), and female communications and low power connector  830  F and male communications and low power connector  830 M can combine to form coupled communications and low power connectors  830   c . As a result, the internal cooling channels or manifolds of the battery modules can be connected through the coupling between the modules, forming the cooling system schematically illustrated in  FIG. 3 . 
     As would be readily appreciated by one of ordinary skill in the art, various embodiments described herein may be used in additional applications, such as in energy-storage systems for wind and solar power generation. Other applications are also possible. 
     The description of the present technology has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. Exemplary embodiments were chosen and described in order to best explain the principles of the present technology and its practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.