Patent Publication Number: US-2023159174-A1

Title: Circular configuration of battery cells for aircraft

Description:
TECHNICAL FIELD 
     This disclosure relates to configurations for battery cells for electric or hybrid-electric aircraft propulsion systems. 
     BACKGROUND 
     Aircraft may be powered by various propulsors (e.g., wheels, fans, or propellers), which may be driven by various motors. For instance, in electric aircraft, an electric motor may drive the propulsors using electrical energy sourced from an electrical energy storage system (ESS) that includes one or more batteries. 
     SUMMARY 
     In general, this disclosure describes circular configurations of battery cells in an aircraft ESS. Most developments for ESS technology have been with respect to individual cell or pouch designs, while packaging of those cells for larger vehicles are largely overlooked. In particular, most packaging designs are based on automotive applications (e.g., where the ESS forms a portion of a floor of the automobile and is flat). However, designs based on automotive application may not consider specific aerospace requirements (e.g., Freight Shipping: UN38.8 requirements, Transport of Dangerous Goods: DO-160G standards, and DO-311 standards). 
     In accordance with one or more aspects of this disclosure, an ESS in an aircraft may include battery cells in a circular configuration. For instance, the ESS may include one or more battery modules that each include a centralized cooling channel and battery pack that includes a plurality of battery cells radially distributed above the centralized cooling channel. The plurality of battery calls may be located within a cylindrical pressure vessel, which may be configured to provide explosion containment (e.g., in compliance with DO-311). A single battery module may include a plurality of battery packs that each include a plurality of battery calls. The plurality of battery packs may be placed end-to-end such that a single cooling channel may pass through each of the plurality of battery packs of the battery module. 
     Several battery modules may be connected together to form the ESS. The battery modules may be arranged in a two-dimensional configuration. For instance, 12 battery modules may be arranged in a four wide by three tall configuration. By arranging the battery modules in the two-dimension configuration, this disclosure may enable battery modules to better fit within aircraft. For instance, the two-dimensional configuration may enable an ESS to be positioned within a wing of an aircraft. 
     As one example, a system includes one or more battery modules, a battery module of the one or more battery modules comprising: a cylindrical pressure vessel; a cooling channel extending axially through the cylindrical pressure vessel; and one or more battery packs within the cylindrical pressure vessel, a battery pack of the one or more battery packs comprising a plurality of battery cells radially distributed about the cooling channel. 
     As another example, an aircraft includes a wing; one or more battery modules positioned in the wing, a battery module of the one or more battery modules comprising: a cylindrical pressure vessel; a cooling channel extending axially through the cylindrical pressure vessel; and one or more battery packs within the cylindrical pressure vessel, a battery pack of the one or more battery packs comprising a plurality of battery cells radially distributed about the cooling channel; and an electric motor coupled to a propulsor configured to propel the aircraft using electrical energy sourced from the one or more battery modules. 
     The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a conceptual block diagram illustrating an aircraft that includes an electrical propulsion system, in accordance with one or more aspects of this disclosure. 
         FIG.  2    is a system diagram illustrating further details of one example of aircraft  2  of  FIG.  1   , in accordance with one or more aspects of this disclosure. 
         FIGS.  3 A and  3 B  are schematic diagrams illustrating views of an ESS that includes a plurality of battery modules, in accordance with one or more aspects of this disclosure. 
         FIG.  4    is a schematic diagram illustrating a cutaway view of a battery module that includes a plurality of battery packs, in accordance with one or more aspects of this disclosure. 
         FIG.  5    is a schematic diagram illustrating a cross section of a battery module, in accordance with one or more aspects of this disclosure. 
         FIG.  6    is a schematic diagram illustrating a cross section of a wing that includes a plurality of battery modules, in accordance with one or more aspects of this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    is a conceptual block diagram illustrating an aircraft that includes an electrical propulsion system, in accordance with one or more aspects of this disclosure. As shown in  FIG.  1   , aircraft  2  includes fuselage  4 , port wing  6 A, starboard wing  6 B, nacelles  8 A- 8 D (collectively, “nacelles  8 ”), and electrical energy storage systems (ESSs)  14 A and  14 B. Examples of aircraft  2  include, but are not limited to, fixed wing airplanes, tilt rotor aircraft, rotorcraft (e.g., helicopters, quadcopters, etc.), or any other flying machine propelled at least in part using electrically driven propulsors. Fuselage  4  may be a main body of aircraft  2  in which passengers and/or cargo are stored. 
     Nacelles  8  may include various components to support operation of aircraft  2 . Nacelles  8  may be distributed on both port and starboard sides of aircraft  2 . For instance, as shown in  FIG.  1   , nacelles  8 A and  8 B may be positioned on a port side of aircraft  2  (e.g., attached to port wing  6 A) and nacelles  8 C and  8 D may be positioned on a starboard side of aircraft  2  (e.g., attached to starboard wing  6 B). Nacelles  8  may be referred to by relative position. For instance, nacelles  8 B and  8 C may be referred to as inboard nacelles (e.g., as they are located closer to fuselage  4  than nacelles  8 A and  8 D). Similarly, nacelles  8 A and  8 D may be referred to as outboard nacelles (e.g., as they are located farther from fuselage  4  than nacelles  8 B and  8 C). 
     One or more of nacelles  8  may include propulsors configured to propel aircraft  2 . For instance, as shown in  FIG.  1   , each of nacelles  8  may include a respective propulsor of propulsors  10 A- 10 D (collectively, “propulsors  10 ”) that is driven by a respective electric motor of electric motors  12 A- 12 D (collectively, “electric motors  12 ”). Examples of propulsors  10  include, but are not limited to, fans, propellers (e.g., either fixed or variable pitch), and the like. Examples of electric motors  12  include, but are not limited to, brushed, brushless, alternating current (AC), direct current (DC), field-wound, permanent magnet, etc. Electric motors  12  may provide rotational energy to propulsors  10  using electrical energy source from one or more components of aircraft  2 , such as ESS  14 A or ESS  14 B. 
     Aircraft  2  may include a plurality of electrical energy storage systems, such as ESS  14 A and ESS  14 B (collectively, “ESSs  14 ”). The ESSs  14  may be configured to store electrical energy for use by one or more components of aircraft  2 , such as electric motors  12 . Each of ESSs  14  may be connected to a respective electrical bus of a plurality of electrical busses. For instance, ESS  14 A may be connected to, and configured to supply electrical energy to, a first electrical bus. Similarly, ESS  14 B may be connected to, and configured to supply electrical energy to, a second electrical bus. 
     In accordance with one or more aspects of this disclosure, each of ESS  14   s  may include battery cells in a circular arrangement. For instance, each of ESSs  14  may include one or more battery modules. As discussed in further detail below, each of the battery modules may include a cylindrical pressure vessel; a cooling channel extending axially through the cylindrical pressure vessel; and one or more battery packs within the cylindrical pressure vessel. The battery packs may each include a plurality of battery cells radially distributed about the cooling channel. 
     As shown in  FIG.  1    and discussed in further detail below, ESSs  14  may be located in wings of aircraft  2 . For instance, ESS  14 A may be located in wing  6 A and ESS  14 B may be located in wing  6 B. As shown in the example of  FIG.  9   , battery modules of ESSs  14  may be located in a forward quarter chord of the wing. In other examples, ESSs  14  may be located in pods or nacelles attached to the wings of aircraft  2 . 
     Aircraft  2  may include protection and distribution components  20  (“PnD  20 ”) that form portions of the electrical busses. PnD  20  may include various distribution panels and electrical cables that facilitate the transfer of electrical energy between components of aircraft  2  (e.g., electric motors  12  and ESSs  14 ). As one example, PnD  20  may include a first distribution panel for the first electrical bus and a second distribution panel for the second electrical bus. The first and second distribution panels may be located in fuselage  4 . As another example, PnD  20  may include several electrical cables. For instance, PnD  20  may include electrical cables connecting ESSs  14  to the distribution panels, and electrical cables connecting the distribution panels to electric motors  12 . As such, in some examples, all of the electrical energy provided by ESSs  14  and utilized by electric motors  12  may flow through the distribution panels. 
       FIG.  2    is a system diagram illustrating further details of one example of aircraft  2  of  FIG.  1   , in accordance with one or more aspects of this disclosure. As shown in  FIG.  2   , each of nacelles  8  may include an electric propulsion unit (EPU) of EPUs  13 A- 13 D (collectively, “EPUs  13 ”). Each of EPUs  13  may include components configured to propel aircraft  2  using electrical energy. For instance, each of EPUs  13  may include an electric motor and a propulsor (e.g., an electric motor of electric motors  12  and a propulsor of propulsors  10  of  FIG.  1   ). In some examples, EPUs  13  may include additional components. For instance, where the electrical busses supplying EPUs  13  are direct current (DC) electrical busses and the electric motors are alternating current (AC) motors, EPUs  13  may each include an inverter configured to convert DC electrical energy into AC electrical energy. 
     ESSs  14 , as shown in  FIG.  2   , may each include a respective converter of converters  28 A and  28 B (collectively, “converters  28 ”), a respective controller of controllers  30 A and  30 B (collectively, “controllers  30 ”), a respective thermal management system (TMS) of TMS  32 A and  32 B (collectively, “TMSs  32 ”), and a respective battery module of battery modules  34 A and  34 B (collectively, “battery modules  34 ”). 
     Converters  28  include components configured to convert electrical energy exchanged between battery modules  34  and electrical busses. For instance, converter  28 A may convert electrical energy between battery module  34 A and a first electrical bus and converter  28 B may convert electrical energy between battery module  34 B and a second electrical bus. In some examples, to convert the electrical energy, converters  28  may adjust a voltage of the electrical energy. For instance, where the first electrical bus is a DC electrical bus (e.g., a 1080 volt DC electrical bus), converter  28 A may include DC/DC converters configured to convert electrical energy between a voltage of battery module  34 A and a voltage of the first electrical bus. Converters  28  may be bi-directional in that converters  28  may convert electrical energy provided by battery modules  34  for use by other components of aircraft  2  and convert electrical energy provided by other components of aircraft  2  for use in charging battery modules  34 . 
     Controllers  30  may be configured to control operation of ESSs  14 . For instance, controller  30 A may be considered a controller of a battery management system that controls operation of converter  28 A, TMS  32 A, and battery module  34 A. 
     TMSs  32  may include components configured to manage a thermal state of ESSs  14 . For instance, each of TMSs  32  may include loops (e.g., heating and/or cooling) configured to manage a temperature of a corresponding ESS of ESSs  14 . As one example, TMS  32 A may include one or more temperature sensors configured to monitor a temperature of battery module  34 A, one or more pumps configured to pump coolant through battery module  34 A, one or more heaters configured to heat the coolant, and a controller that manages operation of the pumps and heaters based on the temperature of battery module  34 A. TMS  32 B may include similar components for battery module  34 B. 
     Battery modules  34  may each include a plurality of battery modules that store electrical energy to be used for propulsion of aircraft  2 . The battery cells in battery modules  34  may be any type of battery. Examples of battery cells include, but are not limited to, lithium-ion, lead-acid, nickel-cadmium, nickel-metal hydride, lithium-ion polymer, or any other type of rechargeable battery (i.e., secondary cell). 
     Wings  6  may include one or more components configured to facilitate operation of battery modules  34 . As one example, wings  6  may each include vents configured to transmit gasses or other particulate (e.g., smoke) from battery modules  34  to outside of aircraft  2 . As another example, wings  6  may each include access panels that enable direct access to battery modules  34  from outside of aircraft  2 . 
     As discussed above, aircraft  2  may include a plurality of electrical busses. For instance, as shown in  FIG.  2   , aircraft  2  may include a respective propulsion bus for each ESS of ESSs  14 . Each of the propulsion busses may be formed from various electrical cables and distribution panels. For instance, a first propulsion bus may be formed from cables and panels used to provide electrical energy to electric motors of outboard nacelles  8 A and  8 D, and a second propulsion bus may be formed from cables and panels used to provide electrical energy to electric motors of inboard nacelles  8 B and  8 C. As shown in  FIG.  2   , the first propulsion bus may include: electrical cables  42 A connecting ESS  14 A to distribution panel  22 A, electrical cables  44 B connecting distribution panel  22 A to EPU  13 B (e.g., to the electric motor of inboard nacelle  8 B), and electrical cables  44 C connecting distribution panel  22 A to EPU  13 C (e.g., to the electric motor of inboard nacelle  8 C). Similarly, the second propulsion bus may include: electrical cables  42 B connecting ESS  14 B to distribution panel  22 B, electrical cables  44 A connecting distribution panel  22 B to EPU  13 A (e.g., to the electric motor of outboard nacelle  8 A), and electrical cables  44 D connecting distribution panel  22 B to EPU  13 D (e.g., to the electric motor of outboard nacelle  8 D). Electric cables  44 A- 44 D (collectively, “electric cables  44 ”) and electric cables  42 A and  42 B (collectively, “electric cables  42 ”) may be any type of electrical cable, such as stranded, solid, and the like. As shown in  FIG.  2   , electric cables  42  and  44  may be routed through wings  6 A and  6 B. 
     Aircraft  2  may include one or more electric busses in addition to the propulsion busses. For instance, aircraft  2  may include one or more low voltage DC busses (e.g., 28 volts) that supply electrical energy to components of aircraft  2  other than propulsion motors (e.g., other than electrical motors  12 ). Some examples of components that may be powered via the low voltage DC busses include avionics and hotel loads (e.g., cabin lighting, cabin climate control, cooking, and the like). As shown in  FIG.  2   , aircraft  2  may include two non-propulsion electrical busses. Each of the non-propulsion electrical busses may include a battery, a distribution panel, and a control switch. For instance, a first non-propulsion electrical bus may include battery  38 A, panel  36 A, and control switch  26 A. Similarly, a second non-propulsion electrical bus may include battery  38 B, panel  36 B, and control switch  26 B. Panels  36 A and  36 B and batteries  38 A and  38 B may be included in nacelles. As shown in  FIG.  2   , panel  36 A and battery  38 A may be located in inboard nacelle  8 B, and panel  36 B and battery  38 B may be located in inboard nacelle  8 C. Control switches  26 A and  26 B may be located in fuselage  4  (e.g., in the cockpit). Activation of control switches  26  may result in activation (e.g., powering up) of the non-propulsion electrical busses, which may result in activation of the propulsion electrical busses. For instance, as shown in  FIG.  2   , ESS  14 A may receive power from panel  36 A and ESS  14 B may receive power from panel  36 B. 
     As shown in  FIG.  2   , inboard nacelles  8 B and  8 C may respectively include landing gear  40 A and  40 B. The presence of landing gear  40 A and  40 B in inboard nacelles  8 B and  8 C may reduce the space available for other components. 
     In some examples, aircraft  2  may be a purely electrically powered aircraft. For instance, EPUs  13  may be entirely powered using electrical energy provided by ESSs  14 . In other examples, aircraft  2  may be a hybrid-electric aircraft. For instance, aircraft  2  may include a combustion operated motor connected to a generator (e.g., a genset) that generates electrical energy for immediate use by EPUs  13  or for storage in ESSs  14 . 
     Aircraft  2  may include a respective charging panel for each of the propulsion busses. For instance, as shown in  FIG.  2   , aircraft  2  may include charging panel  24 A for the first propulsion bus and charging panel  24 B for the second propulsion bus. Each of the charging panels may include components configured to enable the charging of an ESS of ESSs  14  using power sourced from outside of aircraft  2 , such as ground power. 
       FIGS.  3 A and  3 B  are schematic diagrams illustrating views of an ESS that includes a plurality of battery modules, in accordance with one or more aspects of this disclosure. As shown in  FIGS.  3 A and  3 B , ESS  14 A may include battery modules  34 A 1 - 34 C 4  (collectively, “battery modules  34 A”). Battery modules  34 A may be arranged in a two-dimensional structure. For instance, as shown in  FIGS.  3 A and  3 B , battery modules  34 A may be arranged in a four wide by three tall structure. Such an arrangement may be undesirable for cars where the battery modules are located in a floor of the car. 
     While  FIGS.  3 A and  3 B  illustrate ESS  14 A, it is understood that ESS  14 B may include a similar arrangement of battery modules. For instance, ESS  14 B may include a two-dimensional arrangement of battery modules. 
     As discussed above, battery modules may include one or more battery packs. For instance, each of battery modules  34 A may include one or more battery packs. Each of the battery packs may include one or more battery cells. In some examples, battery cells of a battery pack may be in parallel with each other. For instance, where a battery pack includes N (e.g., 2, 3, 4, 5, 6, 7, etc.) cells, the N cells may be electrically in parallel. As one specific example, a battery pack may include five cells that are electrically in parallel (e.g., 5P). Battery packs may be electrically connected in series. For instance, where each battery pack includes N cells and a battery module include M battery packs, the battery module may be in a NPMS arrangement. 
       FIG.  4    is a schematic diagram illustrating a cutaway view of a battery module that includes a plurality of battery packs, in accordance with one or more aspects of this disclosure. As shown in  FIG.  4   , battery module  34 A 1  may include battery packs  50 A- 50 C (collectively, “battery packs  58 ”). Each of battery packs  58  may include battery cells  60 , fire resistant material  62  and/or  64 . Fire resistant material  62  is shown as being removed from battery pack  58 B to illustrate components within battery pack  58 B. Other battery packs (e.g., battery packs  58 A and  58 C) may include components similar to battery pack  58 B. As discussed above, battery cells  60  may be any suitable chemistry, such as lithium ion. 
     Fire resistant materials  62  and  64  may provide various fire resistance to battery packs  58 . As one example, fire resistant material  62  may be a fire suppressant foam (e.g., polyurethane foam) configured to resist propagation of fire/high temperatures from battery cells to outside battery module  34 A 1 . As another example, fire resistant material  64  may be a fire-resistant paper configured to provide both electrical and thermal isolation (e.g., up to 1430 degrees C.). As shown in  FIG.  4   , fire resistant material  64  may be disposed between each of battery cells  64 . 
     Battery packs  58  may be separated by firewalls. For instance, as shown in  FIG.  4   , battery packs  58  may be separated from each other by firewalls  80 . Firewalls  80  may include components configured to prevent propagation of fire between adjacent battery packs. Firewalls  80  may include bus bars. For instance, each of firewalls  80  may include a bus bar connected to terminals of battery calls  60 . As such, each battery pack of battery packs  58  may include a first bus bar connected to first terminals of each of the plurality of battery cells of the battery pack; and a second bus bar connected to second terminals of each of the plurality of battery cells of the battery pack such that the plurality of battery cells are electrically in parallel. 
     While not shown in  FIG.  4    and as discussed in further detail below, battery module  34 A 1  may include a pressure vessel. For instance, battery module  34 A 1  may include a pressure vessel that may surround battery packs  58 . 
       FIG.  5    is a schematic diagram illustrating a cross section of a battery module, in accordance with one or more aspects of this disclosure.  FIG.  5    may be a cross section of battery module  34 A 1 . As shown in  FIG.  5   , battery module  34 A 1  may include battery pack  58 A, cooling channel  66 , and pressure vessel  70 . Battery pack  58 A may include battery cells  60 A- 60 E (collectively, “battery cells  60 ”), fire resistant materials  62  and  64 . As noted above, each battery pack may include similar components. 
     Pressure vessel  70  may surround the battery cells and provide containment (e.g., during a period of sustained thermal runaway as the battery cells out-gas). In some designs, pressure vessel  70  may be a significant weight contributor. Most ESS designs utilize a box-like configuration, where the corners and edges of pressure vessel  70  may require additional material to handle the internal pressure. 
     In accordance with one or more aspects of this disclosure, pressure vessel  70  may be a cylindrical pressure vessel. By using a cylindrical shape, a pressure load may be more evenly distributed, thus minimizing a required material thickness of pressure vessel  70 . Not only does this strategy allow for thinner materials to be used to form pressure vessel  70 , but also lighter and cheaper materials, such as polycarbonate, as an example. 
     Pressure vessel  70  may be formed of exterior skin  72  and/or interior skin  74 . Exterior skin  72  may be formed of polycarbonate or other suitable material. As such, pressure vessel  70  may be at least partially formed from polycarbonate. Interior skin  74  may be formed of phenolic cork or other suitable material. 
     Cooling channel  66  may be configured to carry a coolant fluid to exchange heat with battery cells  60 . Cooling channel  66  may extend axially through battery module  34 A 1 . For instance, cooling channel  66  may extend through a plurality of battery packs of battery module  34 A 1 . As such, a single cooling channel may exchange heat with battery cells of multiple battery packs. 
     Cooling channel  66  may include features configured to support battery cells  60 . For instance, cooling channel  66  may include pedestals  68 A- 68 E (collectively, “pedestals  68 ”). Each of pedestals  68  may be mated to a respective battery cell of battery cells  60 . For instance, as shown in  FIG.  5   , pedestal  68 A may be mated to battery cell  60 A, pedestal  68 B may be mated to battery cell  60 B, . . . , and pedestal  68 E may be mated to battery cell  60 E. 
     Cooling channel  66  may be formed via any suitable process and material. In some examples, cooling channel  66  may be extruded and/or may be formed of magnesium. In operation, coolant fluid may flow through a fluidic path of cooling channel  66 . In some examples, the surface of cooling channel  66  that forms the fluidic path may be modified to disturb a fluid boundary layer (e.g., may be rifled, splined, etc.). In this way, heat exchange efficiency may be improved. 
     In some examples, one or both ends of cooling channel  66  may be threaded or otherwise configured to receive an axial retention component. Such an axial retention component may be attached to cooling channel  66  to provide axial force to act as a “tie-bolt” and restrain battery packs  58 . 
     During operation, due to various reasons, one or more of battery cells  60  may overheat. If left unchecked, an overheating battery cell of battery cells  60  may cause other battery cells of battery cells  60  to overheat. Such an event may be referred to as thermal runaway, which may be undesirable. 
     In accordance with one or more aspects of this disclosure, battery cells  60  may be mated to cooling channel  66  (e.g., pedestals  68  of cooling channel  66 ) via a thermally conductive component of thermally conductive components  76 A- 76 E (collectively, “thermally conductive components  76 ”). Thermally conductive components  76  may be formed of a material such that, during normal operation, thermally conductive components  76  conduct heat between battery cells  60  and cooling channel  66 . However, the material may have a melting point that is lower than a thermal runaway temperature of battery cells  60 . 
     When a thermally conductive component melts, the melted thermally conductive component may flow away from the connection between battery cell and cooling channel, substantially reducing the amount of heat conducted between battery cell and cooling channel. For instance, battery module  34 A 1  may include one or more cavities configured to, where a particular thermally conductive component melts, receive the melted thermally conductive component. As such, when a particular battery cell of battery cells  60  overheats, a thermally conductive component connecting the particular battery cell to cooling channel  66  may melt before the particular battery cell can transmit enough heat to cause another battery cell to overheat. For instance, where battery cell  60 A overheats, thermally conductive component  76 A may melt before heat from battery cell  60 A causes battery cell  60 A or  60 B to overheat (e.g., act as a thermal fuse). In this way, aspects of this disclosure may reduce a probability of thermal runaway. 
     While described with reference to battery module  34 A 1 , it is understood that each battery module of battery modules  34  may include a respective cooling channel. In some examples, cooling channels of multiple battery modules may be linked to form a single coolant loop. For instance, as shown in  FIGS.  3 A and  3 B , ESS  14 A may include connectors  54  that fluidically couple cooling channels of different battery modules  34 . As such, in some examples, a first battery module of battery modules  34  may include a fluid inlet port that receives coolant fluid from a pump/radiator and a last battery module of battery modules  34  may include a fluid output port that provides coolant fluid to the pump/radiator. In between the fluid inlet port and the fluid outlet port, the coolant fluid may pass through cooling channels of each of battery modules  34  (e.g., via connectors  54  between cooling channels). 
     While described above as being fluidically in series, cooling channels of battery modules  34  are not so limited. For instance, the cooling channels of battery modules  34  may be fluidically connected in parallel, or may be broken down in a series/parallel arrangement. 
     As discussed above, the circular configuration of battery cells described herein may be advantageous for aircraft. For instance, by having the battery cells radially distributed about the cooling channel, a weight efficiency of an ESS may be improved. As one specific example, the weight efficiency of the ESS may be improved such that a ratio of a weight of the plurality of battery cells to a weight of the battery module is greater than or equal to 0.6. 
       FIG.  6    is a schematic diagram illustrating a cross section of a wing that includes a plurality of battery modules, in accordance with one or more aspects of this disclosure. As shown in  FIG.  6   , battery modules  34 A of ESS  14 A may be located in a forward quarter chord of wing  6 A. Battery modules  34 A may be oriented in wing  6 A such that a longitudinal axis of the plurality of battery modules (e.g., an axis parallel to the cooling channels) is substantially parallel to a leading edge of the wing. 
     The following examples may illustrate one or more aspects of the disclosure: 
     Example 1. A system comprising: one or more battery modules, a battery module of the one or more battery modules comprising: a cylindrical pressure vessel; a cooling channel extending axially through the cylindrical pressure vessel; and one or more battery packs within the cylindrical pressure vessel, a battery pack of the one or more battery packs comprising a plurality of battery cells radially distributed about the cooling channel. 
     Example 2. The system of example 1, wherein the cooling channel further comprises: a plurality of pedestals, each respective pedestal of the plurality of pedestals mated to a respective battery cell of the plurality of battery cells via a respective thermally conductive component of a plurality of thermally conductive components. 
     Example 3. The system of example 2, wherein the plurality of thermally conductive components are formed of a material having a melting point that is lower than a thermal runaway temperature of the plurality of battery cells, the battery modules further comprising: one or more cavities configured to, where a particular thermally conductive component melts, receive the melted thermally conductive component. 
     Example 4. The system of any of examples 1-3, wherein the battery pack further comprises: a first bus bar connected to first terminals of each of the plurality of battery cells; and a second bus bar connected to second terminals of each of the plurality of battery cells such that the plurality of battery cells are electrically in parallel. 
     Example 5. The system of any of examples 1-4, wherein the battery pack further comprises fire resistant material disposed between each of the plurality of battery cells. 
     Example 6. The system of any of examples 1-5, wherein the one or more battery packs comprises a plurality of battery packs, each respective battery pack of the plurality of battery packs comprising a respective plurality of battery cells radially distributed about the cooling channel. 
     Example 7. The system of example 6, wherein battery cells of each battery pack are electrically connected in parallel, and wherein the plurality of battery packs are connected in series. 
     Example 8. The system of any of examples 1-7, wherein the one or more battery modules comprises a plurality of battery modules arranged in a two-dimensional structure. 
     Example 9. The system of example 8, wherein the plurality of battery modules are located in a wing of an aircraft. 
     Example 10. The system of example 9, wherein the plurality of battery modules are located in a forward quarter chord of the wing. 
     Example 11. The system of any of examples 8-10, wherein a longitudinal axis of the plurality of battery modules is substantially parallel to a leading edge of the wing. 
     Example 12. The system of any of examples 9-11, further comprising: an electric motor coupled to a propulsor configured to propel the aircraft using electrical energy sourced from the one or more battery modules. 
     Example 13. The system of examples 8-12, wherein each respective battery module of the plurality of battery modules comprises a respective cooling channel of a plurality of cooling channels, the system further comprising: one or more pumps configured to circulate coolant fluid through the plurality of cooling channels. 
     Example 14. The system of examples 8-13, wherein each respective battery module of the plurality of battery modules comprises a respective cooling channel of a plurality of cooling channels, the system further comprising: one or more connectors configured to fluidically connect cooling channels of a pair of battery modules of the plurality of battery modules. 
     Example 15. The system of any of examples 1-14, wherein each of the plurality of battery cells comprises a lithium-ion battery cell. 
     Example 16. The system of any of examples 1-15, wherein the plurality of battery cells comprises five battery cells. 
     Example 17. The system of any of examples 1-16, wherein a ratio of a weight of the plurality of battery cells to a weight of the battery module is greater than or equal to 0.6. 
     Example 18. The system of any of examples 1-17, wherein the cylindrical pressure vessel is at least partially formed from polycarbonate. 
     Various examples have been described. These and other examples are within the scope of the following claims.