Patent Description:
Batteries are commonly used in vehicles, such as electric vehicles (e.g., electric aircraft), to provide electrical power to one or more systems of the vehicle and/or provide the main power to propel the vehicle. These batteries commonly face temperature fluctuations, such as temperature increases. Such increases in battery temperature may cause the batteries to malfunction and/or fail. Keeping the batteries within a functional temperature range is challenging but important since fluctuations in battery temperature not only reduce the performance of the battery, but could also pose safety risks associated with battery failure during vehicle operation.

<CIT>, in accordance with its abstract, states a battery cooling device for cooling a plurality of lithium ion batteries in which electrode terminals are connected to each other, comprising a pair of through-holes which allows the electrode terminals of adjacent lithium ion batteries pass therethrough and fit thereto, and an insulating cooling liquid passage avoiding these through-holes, circulating over almost the whole, and facing outward openings at both ends are installed in a connecting conductor connecting electrode terminals of the adjacent lithium ion batteries, the insulating cooling liquid passages in a plurality of connecting conductors are connected in a series through an insulating pipe, and the insulating cooling liquid is circulated through the cooling liquid passage of each connecting conductor with a circulation pump.

<CIT>, in accordance with its abstract, states a battery module that includes a plurality of electrochemical cells, each with a pair of electrical terminals, a first elongated member, electrically connecting a first terminal of at least one cell of the electrochemical cells to a second terminal of at least one other cell, and a second elongated member, electrically connecting a third terminal of at least one of the cells to a fourth terminal of at least one other cell, wherein at least a portion of the first and second elongated members is a hollow section defining a fluid pathway configured to transmit a fluid for transferring heat to or from the electrical terminals of the electrochemical cells.

<CIT>, in accordance with its abstract, states a battery assembly that includes a plurality of batteries operably positioned to be charged and discharged. At least a first battery and a second battery of the plurality of batteries include a stack of electrochemical cells encased in an electrically inert case. A pair of battery tabs outwardly extends from the case. At least the first battery and the second battery in the battery assembly are configured to be electrically connected through their battery tabs with one or more hollow busbars forming a passage for a coolant flow.

<CIT>, in accordance with its abstract, states a coolant cooling type battery that includes battery cells each having tabs to electrically connect the battery cells to each other by respective tabs. The respective tabs of the battery cells are arranged in a unidirectional alignment. Additionally, the battery includes busbars each interconnecting the tabs of adjacent battery cells of the multiple battery cells with each other to form an electrical connection between the battery cells and a coolant channel that is connected to the multiple busbars and has coolant flowing therein.

According to one aspect disclosed herein, a battery according to claim <NUM> is provided.

An example battery disclosed herein may include a housing defining a cavity, a battery cell disposed in the cavity of the housing, and a cooling fluid in the cavity of the housing that at least partially submerges the battery cell. The cooling fluid partially fills the cavity such that an air gap is formed between a top surface of the cooling fluid and a top of the housing. The example battery also includes a cooling circuit disposed in the air gap.

An example method disclosed herein may include determining a temperature of a battery. The battery includes a bus bar having a fluid channel formed therein. The method includes comparing the temperature to a threshold, and, in response to determining that the temperature exceeds the threshold, activating a pump to pump cooling fluid through the fluid channel in the bus bar to reduce the temperature of the battery.

The figures are not to scale. In general, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts. As used herein, unless otherwise stated, the term "above" describes the relationship of two parts relative to Earth. A first part is above a second part, if the second part has at least one part between Earth and the first part. Likewise, as used herein, a first part is "below" a second part when the first part is closer to the Earth than the second part. As noted above, a first part can be above or below a second part with one or more of: other parts therebetween, without other parts therebetween, with the first and second parts touching, or without the first and second parts being in direct contact with one another. As used in this application, stating that any part (e.g., a layer, film, area, region, or plate) is in any way on (e.g., positioned on, located on, disposed on, or formed on, etc.) another part, indicates that the referenced part is either in contact with the other part, or that the referenced part is above the other part with one or more intermediate part(s) located therebetween. As used herein, connection references (e.g., attached, coupled, connected, and joined) may include intermediate members between the elements referenced by the connection reference and/or relative movement between those elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and/or in fixed relation to each other. As used herein, stating that any part is in "contact" with another part is defined to mean that there is no intermediate part between the two parts.

Unless specifically stated otherwise, descriptors such as "first," "second," "third," etc. are used herein without imputing or otherwise indicating any meaning of priority, physical order, arrangement in a list, and/or ordering in any way, but are merely used as labels and/or arbitrary names to distinguish elements for ease of understanding the disclosed examples. " In such instances, it should be understood that such descriptors are used merely for identifying those elements distinctly that might, for example, otherwise share a same name. As used herein, "approximately" and "about" refer to dimensions that may not be exact due to manufacturing tolerances and/or other real-world imperfections.

Batteries, such as lithium-ion batteries, are commonly used in vehicles such as electric vehicles. For example, electric aircraft typically include one or more lithium-ion batteries to power one or more electric motors for flying the aircraft and/or for powering other electrical systems (e.g., navigation and guidance systems, communication systems, etc.) on the aircraft. Although lithium-ion batteries are just one example of the types of batteries that can be used in vehicles, they are growing increasingly popular among aircraft manufacturers due to their higher energy density and lower weight compared to other battery types. However, a tradeoff to their improved energy capacity and weight characteristics is their potential to overheat and malfunction during use. Thus, thermal management of these batteries is important. Maintaining a battery within a certain temperature range is important not only for mitigating the risk of a thermal runaway event in one or more battery cells but also for extending the cycle life of the battery.

Currently, there exist a number of known technologies in aviation and other industries for cooling batteries in events of temperature increase and providing uniform temperature control to battery environments. For example, some known batteries include coolant or a cooling fluid that fully fills the battery cavity and submerges the individual battery cells. Other known batteries utilize cooling pipes that are routed between each of the battery cells. A drawback to these solutions is the added weight that these cooling methods and supplemental equipment incur on the battery system in order to accomplish effective cooling.

Disclosed herein are example batteries and battery systems that address at least the above-noted drawbacks. Disclosed herein is a battery including a bus bar with a fluid channel formed in the bus bar. The fluid channel is part of a cooling circuit including a pump and supply/return lines (which can be external to the battery). The pump can be activated to pump cooling fluid into the battery and through the fluid channel in the bus bar (to absorb heat from the bus bar). This operation reduces the temperature of the bus bar and, thus, reduces the temperature inside of the battery, thereby helping to maintain the battery within a certain operating temperature range. Using the bus bar to form part of the fluid circuit eliminates the need for additional cooling pipes in the battery as seen in known cooling designs. This significantly reduces the weight of the battery compared to known batteries with piping systems.

In some examples, the cooling fluid is continuously pumped through the bus bar to regulate the temperature of the battery. The mass flow of the cooling fluid can be increased or decreased to maintain the temperature of the battery within a certain temperature range. In other examples, the pump can be activated when the temperature of the battery exceeds a threshold. In some examples the cooling fluid is a liquid. In other examples, the cooling fluid is a gas.

In some examples disclosed herein, the battery includes a second cooling fluid in a housing of the battery that contains the one or more battery cells. The second cooling fluid at least partially submerges the battery cells. The second cooling fluid absorbs heat from the battery cells and helps regulate the temperature of the battery. In some examples, the second cooling fluid only partially fills the housing of the battery. As such, an air gap is formed between a top of the second cooling fluid and a top of the housing. This also reduces the weight of the battery compared to known batteries that are completely fulfilled with cooling fluid. During a temperature increase event, the second cooling fluid surrounding the battery cells undergoes a phase change from a liquid state to a gaseous state. The gas rises in the housing and then condenses on the surface of the bus bar, thus reducing the temperature of the battery cells.

Thus, the examples disclosed herein provide a battery including a bus bar with a fluid channel connected to one or more cells, which are submerged in a phase changing cooling fluid. The examples disclosed herein provide a thermal management solution for batteries to control battery temperature during temperature increases and prevent thermal runaway events. The examples of the subject disclosure address the shortcomings of current battery cooling techniques noted above.

<FIG> illustrates an example aircraft <NUM> in which one or more of the example batteries and/or example battery systems disclosed herein can be implemented. The aircraft <NUM> can be a manned or unmanned aerial vehicle. In this example, the aircraft <NUM> is an electric aircraft. However, in other examples, the aircraft <NUM> can be powered by other means (e.g., gas-powered). The aircraft <NUM> illustrated in <FIG> is an electric vertical take-off and landing (VTOL) aircraft having a plurality of vertical lift rotors <NUM> (one of which is referenced in <FIG>) driven by respective electric motors <NUM> (one of which is referenced in <FIG>). The aircraft <NUM> also has a forward propulsion rotor <NUM> driven by a motor. The example batteries and/or battery systems disclosed herein can be used to provide electrical power to the motors <NUM> (and the motor that drives the rotor <NUM>) and/or any other electrical system on the aircraft <NUM>. In some examples, the one or more batteries are disposed inside a body <NUM> (e.g., a fuselage) of the aircraft <NUM>. While in this example the aircraft <NUM> is implemented as a VTOL aircraft, in other examples, the aircraft <NUM> can be implemented as any other type of aircraft (e.g., a fixed wing aircraft, a rotorcraft such as a helicopter or quadcopter, etc.). Further, it is noted that although the subject disclosure describes an aircraft <NUM>, one or more of the example batteries and/or example battery systems disclosed herein can be implemented in any vehicle (e.g., ground and/or water vehicles).

<FIG> are perspective views of opposite sides of an example battery <NUM> constructed in accordance with the teachings of this disclosure. The example battery <NUM> (or multiple ones of the battery <NUM>) can be implemented in the aircraft <NUM> of <FIG>. The battery <NUM> includes a housing <NUM> that contains one or more battery cells (shown in <FIG>). In this example, the housing <NUM> is cuboid shape. In particular, the housing <NUM> has a first sidewall <NUM>, a second sidewall <NUM> that is opposite to the first sidewall <NUM>, a first end wall <NUM> that is coupled between the first sidewall <NUM> and the second sidewall <NUM>, and a second end wall <NUM> that is coupled between the first sidewall <NUM> and the second sidewall <NUM> and is opposite to the first end wall <NUM>. In other examples, the housing <NUM> can include more than four side/end walls. The housing <NUM> also includes a bottom wall <NUM> is coupled to the first sidewall <NUM>, the first end wall <NUM>, the second sidewall <NUM>, and the second end wall <NUM> to define a base of the housing <NUM>. The housing <NUM> has a lid <NUM> (e.g., a top) that is coupled to the first and second side walls <NUM>, <NUM> and the first and second end walls <NUM>, <NUM> opposite to the bottom wall <NUM>. In some examples, the lid <NUM> is removable to access the battery cells and/or other components in the housing <NUM>.

In some examples, the housing <NUM> is hermetically sealed. In some examples, the housing <NUM> is constructed of a composite material. In some examples, the housing <NUM> is constructed of stainless steel, titanium, and/or aluminum. In other examples, the housing <NUM> is constructed of other types of materials. In some examples, the housing <NUM> is designed to withstand internal pressures of approximately <NUM> bar. In other examples, housing <NUM> can be designed to withstand higher or lower internal pressures.

In the illustrated example, the first end wall <NUM> has an interface portion <NUM> with one or more ports and terminals for fluid connections and electrical connections. For example, the example battery <NUM> includes a first terminal <NUM> and a second terminal <NUM>. One of the terminals <NUM>, <NUM> can be a positive terminal and the other of the terminals <NUM>, <NUM> can be a negative terminal. In this example, the terminals <NUM>, <NUM> are on the interface portion <NUM> on the first end wall <NUM>. However, in other examples, the terminals <NUM>, <NUM> can be on any other surface of the housing <NUM>.

In the illustrated example, the interface portion <NUM> includes a first inlet port <NUM> and a first outlet port <NUM>. The first inlet and outlet ports <NUM>, <NUM> extend through the first end wall <NUM> and into the cavity defined in the housing <NUM>. The first inlet and outlet ports <NUM>, <NUM> can be connected to supply and return lines, respectively, for pumping cooling fluid through a first bus bar disposed inside of the housing <NUM>, examples of which are disclosed in further detail herein. The interface portion <NUM> also includes a second inlet port <NUM> and a second outlet port <NUM> for a second bus bar. The interface portion <NUM> further includes a valve port <NUM>. A pressure release valve <NUM> (e.g., a blow-off valve) is disposed in the valve port <NUM> and can release pressure from inside the housing <NUM> during an over-pressurization event. While in this example the ports <NUM>-<NUM> are disposed on the interface portion <NUM> on the first end wall <NUM>, in other examples, any of the ports <NUM>-<NUM> can be disposed on any other surface of the housing <NUM>.

<FIG> is a perspective cross-sectional view of the battery <NUM> taken along line A-A in <FIG>. The lid <NUM> (<FIG>) has also been removed. As shown in <FIG>, the housing <NUM> defines a cavity <NUM>. The battery <NUM> includes a plurality of battery cells <NUM> (one of which is referenced in <FIG>) disposed in the cavity <NUM> of the housing <NUM>. In this example, the battery <NUM> includes <NUM> battery cells. However, it is understood that the battery <NUM> can include any number of battery cells <NUM> (e.g., one battery cell, two battery cells, three battery cells, etc.). Each of the battery cells <NUM> has a first terminal <NUM> (one of which is referenced in <FIG>) and a second terminal <NUM> (one of which is reference in <FIG>). The terminals <NUM>, <NUM> are sometimes referred to as tabs. The first terminals <NUM> can be positive terminals and the second terminals <NUM> can be negative terminals. The first terminals <NUM> of the battery cells <NUM> can be electrically coupled (in a series or parallel arrangement) to one of the terminals <NUM>, <NUM>, and the second terminals <NUM> of the battery cells <NUM> can be electrically coupled (in a series or parallel arrangement) to the other one of the terminals <NUM>, <NUM>.

In some examples, the battery cells <NUM> are lithium-ion battery cells. In other examples, the battery cells <NUM> can be implemented as other types of battery cells, such lithium polymer cells, nickel cadmium cells, or nickel-metal hydride, for example. In some examples, the battery cells <NUM> are grouped into sections or bricks. In some examples, the bricks are 3D printed aluminum alloy (e.g., Al-Alloy AlSi10Mg, Scalmalloy), with integrated features optimizing functionalities and weight. In some examples, the battery cells <NUM> are pouch cells, whereas other examples can include cylindrical battery cell(s) or prismatic cell(s). In the illustrated example, the battery cells <NUM> are arranged in a single row between the first end wall <NUM> and the second end wall <NUM>. In other examples, the battery cells <NUM> can be arranged in two or more rows or other configurations. In some examples, the battery cells <NUM> are supported by and rest on the bottom wall <NUM>. In other examples, the battery cells <NUM> can be spaced apart from the bottom wall <NUM>. In some examples, the housing <NUM> includes features for the battery cells <NUM> to rest on. During use or operation of the battery <NUM>, the temperature of the battery <NUM> environment can increase and, if not controlled, can cause a thermal runaway event in one or more of the battery cells <NUM>.

As shown in <FIG>, the battery <NUM> includes a first bus bar <NUM> and a second bus bar <NUM>. The first and second bus bars <NUM>, <NUM> are disposed in the cavity <NUM> of the housing <NUM>. The first terminals <NUM> of the battery cells <NUM> are coupled (e.g., electrically coupled) to the first bus bar <NUM>. The first bus bar <NUM> is constructed of a conductive material, such as metal (e.g., copper, aluminum, etc.). As such, the first bus bar <NUM> electrically couples the first terminals <NUM> of the battery cells <NUM> (which results in added voltage and/or current of the cells, depending on the arrangement) to the first terminal <NUM> of the battery <NUM>. In some examples, the first terminals <NUM> extend through corresponding slots in the first bus bar <NUM> and are welded (e.g., laser welded) to the first bus bar <NUM>. In other examples, the first terminals <NUM> can be coupled to the first bus bar <NUM> in other manners. The second terminals <NUM> are similarly coupled to the second bus bar <NUM>, which electrically couples the second terminals <NUM> to the second terminal <NUM> of the battery <NUM>. In some examples the first and second bus bars <NUM>, <NUM> rest on the tops of the battery cells <NUM>. In other examples, the first and second bus bars <NUM>, <NUM> are spaced apart from the tops of the battery cells <NUM>.

<FIG> is a perspective view of the example battery cells <NUM> (one of which is referenced in <FIG>) and the first and second bus bars <NUM>, <NUM> as removed the housing <NUM> (<FIG>, and <FIG>). As illustrated in <FIG>, an example fluid channel <NUM> is formed in the first bus bar <NUM>. The fluid channel <NUM> is formed between an inlet port <NUM> (e.g., an opening) on the first bus bar <NUM> and an outlet port <NUM> on the first bus bar <NUM>. The fluid channel <NUM> is to receive a cooling fluid to cool the first bus bar <NUM> and reduce a temperature of the battery <NUM>. In particular, a cooling fluid can be pumped through the fluid channel <NUM> from the inlet port <NUM> to the outlet port <NUM>. The cooling fluid absorbs heat from the first bus bar <NUM>, thereby reducing the temperature of the first bus bar <NUM> and, thus, reducing the temperature of the battery <NUM>. The cooling fluid can be non-conductive dielectric fluid (e.g., a <NUM> NOVEC fluid, ethylene glycol, propylene glycol, etc.). An example system used for pumping cooling fluid through the fluid channel <NUM> is disclosed in conjunction with <FIG>. Thus, the first bus bar <NUM> has a dual purpose of serving as a bus bar (a tab/electrical interface) and serving as at least a portion a cooling circuit or heat sink. This significantly reduces the weight of the battery <NUM> compared to known batteries that have separate cooling circuits with complex piping systems that route cooling fluid between the cells and throughout the battery. Example aspects of the first bus bar <NUM> are disclosed in further detail herein. The second bus bar <NUM> is substantially the same as the first bus bar <NUM>. Thus, it is understood that any of the example aspects disclosed in connection with the first bus bar <NUM> can likewise apply to the second bus bar <NUM>.

As disclosed above, the first bus bar <NUM> has the inlet port <NUM> and the outlet port <NUM> to enable the cooling fluid to enter the example fluid channel <NUM> of the first bus bar <NUM> at the inlet port <NUM> and exit the example fluid channel <NUM> of the first bus bars <NUM> from the outlet port <NUM>. In some examples, the inlet port <NUM> and the outlet port <NUM> are on a same end or side of the first bus bar <NUM>. For example, as shown in <FIG>, the first bus bar <NUM> has a first end <NUM> and a second end <NUM> opposite the first end <NUM>. In the illustrated example, the inlet port <NUM> and the outlet port <NUM> are on the first end <NUM> of the first bus bar <NUM>. The first end <NUM> of the first bus bar <NUM> is engaged with the inside of the first end wall <NUM> (<FIG>). The first inlet port <NUM> (<FIG>) on the first end wall <NUM> (<FIG>) is aligned with the inlet port <NUM> of the first bus bar <NUM>. As such, the inlet port <NUM> is fluidly coupled to the first inlet port <NUM> (<FIG>). Similarly, the first outlet port <NUM> (<FIG>) on the first end wall <NUM> (<FIG>) is aligned with the outlet port <NUM> on the first bus bar <NUM>.

In the illustrated example, the example fluid channel <NUM> forms a C-shaped or a U-shaped path through the first bus bar <NUM> between the inlet port <NUM> and the outlet port <NUM>. For example, a first portion <NUM> of the fluid channel <NUM> traverses along a first edge <NUM> of the first bus bar <NUM> and a second portion <NUM> of the fluid channel <NUM> traverses along a second edge <NUM> of the first bus bar <NUM>, and the first and second portions <NUM>, <NUM> are coupled by a transverse portion <NUM>. In some examples, a top surface <NUM> of the first bus bar <NUM> is recessed <NUM> between the first and second portions <NUM>, <NUM> of the fluid channel <NUM>. In some examples, another cooling fluid that is in the battery <NUM> can accumulate or rest in the recess <NUM> of the first bus bar <NUM>, as disclosed in further detail herein.

In other examples, the inlet port <NUM> and outlet port <NUM> can be disposed on opposite ends of the first bus bar <NUM>. For example, the inlet port <NUM> can be disposed on the first end <NUM> of the first bus bar <NUM> and/or the outlet port <NUM> can be disposed on the second end <NUM> of the first bus bar <NUM>. In the illustrated example, the inlet port <NUM> of the first bus bar <NUM> is disposed closer to a center line of the battery cells <NUM>, such that new cooling fluid entering the fluid channel <NUM> is first transported along the center line area of the battery cells <NUM>, which is typically the hottest area. However, in other examples, the inlet and outlet ports <NUM>, <NUM> can be switched. Further, in other examples, the path of the fluid channel <NUM> forms an alternate shaped path through the first bus bar <NUM> between the inlet port <NUM> and the outlet port <NUM>.

In the illustrated example, the first and second bus bars <NUM>, <NUM> are positioned parallel to each other. In some examples, the bus bars <NUM>, <NUM> can have equivalent structures and/or compositions following the teachings disclosed herein. For example, the second bus bar <NUM> has a fluid channel <NUM> between an inlet port <NUM> and an outlet port <NUM>. The inlet and outlet port <NUM>, <NUM> align with the second inlet and outlet ports <NUM>, <NUM> (<FIG>) on the first end wall <NUM> (<FIG>). However, in other examples, the bus bars <NUM>, <NUM> can have alternate structures and/or compositions.

<FIG> is an enlarged perspective view of the ends of the first and second bus bar <NUM>, <NUM> of <FIG>. The inlet and outlet ports <NUM>, <NUM> are shown in <FIG>. In some examples, the first bus bar <NUM> is constructed of multiple bus bar sections that are coupled together. For example, in <FIG>, the first bus bar <NUM> includes a first section 504a, a second section 504b, a third section 504c, and a fourth section 504d. Each of the sections 504a-504d can be electrically coupled to one or more of the battery cells <NUM> (one of which is referenced in <FIG>). For example, the first section 504a is coupled to the first terminals <NUM> (one of which is referenced in <FIG>) of the first four battery cells <NUM>, the second section 504b is coupled to the first terminals <NUM> of the next four battery cells <NUM>, and so forth. This enables the battery cells <NUM> to be electrically combined into discrete groups of battery cells (sometimes referred to as bricks). The first bus bar <NUM> can include any number of sections (e.g., one section, two sections, etc.). In some examples, the first bus bar <NUM> includes two bridge seals (e.g., spacers) between each of the sections 504a-504d. For example, the battery <NUM> includes first and second bridge seals 506a, 506b between the first and second sections 504a, 504b, third and fourth bridge seals 506c, 506d between the second and third sections 504b, 504c, etc. In some examples, the section 504a-504d and the bridge seals 506a-506d are coupled via an adhesive. In other examples, the sections 504a-504d and the bridge seals 506a-506d can be coupled via other techniques (e.g., friction fit, mechanical fasteners, etc.). The bridge seals 506a-506d help to fluidly coupled the sections of the fluid channel <NUM> formed in the sections 504a-504d and also electrically isolates the sections 504a-504d. In some examples, the bridge seals <NUM> are constructed of insulating or non-conductive material (e.g., plastic, rubber, etc.).

<FIG> is an exploded view of the first and second sections 504a, 504b of the first bus bar <NUM> (<FIG>) and the first and second bridge seals 506a, 506b. The first and second bridge seals 506a, 506b are to be coupled (e.g., clamped) between an end <NUM> of the first section 504a and an end <NUM> of the second section 504b. The first bridge seal 506a has an opening <NUM> that is aligned with a first section <NUM> of the fluid channel <NUM> formed in the first section 504a and a second section <NUM> of the fluid channel <NUM> formed in the second section 504b. When the first bus bar <NUM> is assembled, the first bridge seal 506a fluidly couples the sections <NUM>, <NUM> of the fluid channel <NUM> formed in the first and second sections 504a, 504b, respectively. This enables a substantially continuous flow path for the cooling fluid between the first and second sections 504a, 504b. In some examples, at least a portion of the first bridge seal 506a extends into the first and second sections 504a, 504b. The second bridge seal 506b similarly fluidly couples the other sections of the fluid channel <NUM> formed in the first and second sections 504a, 504b.

<FIG> is a cross-sectional view showing the first bridge seal 506a between the first section 504a and the second section 504b taken along the opening <NUM> in the first bridge seal 506a. As shown in <FIG>, the first bridge seal 506a has a spacer portion <NUM> and a tubular portion <NUM> extending in opposite directions from the spacer portion <NUM>. The tubular portion <NUM> extends in the fluid channel <NUM> formed in the first and second sections 504a, 504b. The spacer portion <NUM> has a larger diameter than the tubular portion <NUM> and physically separates the first and second section 504a, 504b. The opening <NUM> fluidly couples the sections of the fluid channel <NUM> formed in the first section 504a and the second section 504b. As such, the first bridge seal 506a enables cooling fluid to flow between the first and second sections 504a, 504b. Further, the first bridge seal 506a electrically isolates the first and second sections 504a, 504b. Thus, the interface formed by the first bridge seal 506a between the first and second sections 504a, 504b can maintain electrical separation across the first and second sections 504a, 504b while allowing a cooling fluid to flow continuously throughout the fluid channel <NUM>. The other bus bar sections 504b-504d and bridge seals 506c, 506d are similarly arranged. Thus, each of the bus bar sections 504a-504d is electrically isolated from the other adjoining bus bar sections 504a-504d but can maintain circulation of the cooling fluid through the fluid channel <NUM> without breaks.

Referring back to <FIG>, the example battery <NUM> includes a central spine <NUM> disposed between the first bus bar <NUM> and the second bus bar <NUM>. In some examples, the central spine <NUM> traverses along a centerline of the battery cells <NUM>. In some examples, the housing <NUM> (<FIG>) includes features on which the central spine <NUM> can rest. The first and second bus bars <NUM>, <NUM> are mechanically and electrically coupled to the central spine <NUM>. In particular, each of the sections of the first and second bus bars <NUM>, <NUM> is electrically coupled to the central spine <NUM>. The central spine <NUM> includes circuitry to measure and monitor the voltage of the battery cells <NUM> and/or the groups (bricks) of the battery cells <NUM> at each of the sections. If one or more of the battery cells <NUM> and/or the groups of battery cells <NUM> is outputting too much power, the circuitry can turn off or deactivate the battery <NUM>, for example. In some examples, the central spine <NUM> is a circuit board, such as a printed circuit board (PCB).

<FIG> illustrates an example battery system <NUM> including the example battery <NUM> and an example control system <NUM> implemented in connection with the example battery <NUM>. In particular, <FIG> shows a cross-sectional side view of the example battery <NUM> and a schematic of the example control system <NUM>. The control system <NUM> can be used to pump a cooling fluid <NUM>, referred to herein as the first cooling fluid <NUM>, through the first and second bus bars <NUM>, <NUM> (only the first bus bar <NUM> is visible in <FIG>), as disclosed in further detail below.

In some examples, the battery <NUM> includes a cooling fluid <NUM>, referred to herein as the second cooling fluid <NUM>, in the cavity <NUM> of the housing <NUM>. In <FIG>, reference number <NUM> points to the top surface of the second cooling fluid <NUM>. The second cooling fluid <NUM> is separate from the first cooling fluid <NUM> that is pumped through the first bus bars <NUM>. The battery cells <NUM> (one of which is referenced in <FIG>) are at least partially submerged in the second cooling fluid <NUM>. In some examples, such as shown in <FIG>, the battery cells <NUM> are fully submerged in the second cooling fluid <NUM>. In the illustrated example, the surface of the second cooling fluid <NUM> is above the tops of the battery cells <NUM>, but below the first and second bus bars <NUM>, <NUM>. In some examples, the battery cells <NUM> are spaced apart from each other, such that the second cooling fluid <NUM> can flow between the battery cells <NUM>. The second cooling fluid <NUM> draws heat away from the battery cells <NUM> (and distributes the heat evenly around the battery <NUM>), which helps reduce the temperature of the battery <NUM>. The second cooling fluid <NUM> can be a dielectric fluid, such as a <NUM> NOVEC <NUM> Engineered Fluid. In some examples, the second cooling fluid <NUM> is an evaporating fluid. In some examples, the cooling fluid <NUM> is the same type of cooling fluid as the first cooling fluid <NUM>, whereas, in other examples, the cooling fluids can be different types of cooling fluids.

In some examples, the cavity <NUM> is only partially filled with the second cooling fluid <NUM>. In other words, the second cooling fluid <NUM> does not completely fill the cavity <NUM>. This reduces the overall weight of the battery <NUM> compared to known batteries, which is beneficial in aerospace applications where weight is a concern. As shown in <FIG>, an air gap <NUM> is formed between the top surface of the example cooling fluid <NUM> and the lid <NUM> (e.g., the top) of the housing <NUM>. In some examples, when the battery cells <NUM> increase in temperature, at least some of the second cooling fluid <NUM> undergoes a phase change from a liquid state to a gaseous state. For example, during operation, the battery cells <NUM> may become hot, which heats up the second cooling fluid <NUM> and causes some of the second cooling fluid <NUM> to evaporate. The evaporated portion of the second cooling fluid <NUM> rises into the air gap <NUM> where the first and second bus bar <NUM>, <NUM> are located. The first and second bus bars <NUM>, <NUM> can have a lower temperature due to the first cooling fluid <NUM> being pumped through the fluid channel <NUM> of each bus bars <NUM>, <NUM>. As a result, the evaporated portion of the second cooling fluid <NUM> condenses onto the first and second bus bars <NUM>, <NUM>. In some examples, the condensed cooling fluid collects or accumulates in the recess <NUM> (<FIG>) on the top surfaces of the first and second bus bars <NUM>, <NUM>. The condensed portion of the second cooling fluid <NUM> drips over the edges or sides of the bus bars <NUM>, <NUM> and returns to the base of the cavity <NUM>. In some examples, the first and second bus bars <NUM>, <NUM> have one or more pores or openings through which the condensed cooling fluid can drain. This cycle (evaporate and condense) can repeat continuously and helps to reduce the temperature of the battery <NUM>. In this example, the bus bars <NUM>, <NUM> form a cooling circuit in the air gap <NUM> that draws the heat from the evaporated portion of the second cooling fluid <NUM>, thereby enabling the second cooling fluid <NUM> to condense and complete the cooling cycle. However, in other examples, other mechanisms can be used as the cooling circuit in the air gap <NUM>. As such, the second cooling fluid <NUM> can reduce the temperature of the example battery <NUM> to cool the battery <NUM> during high temperature operation and/or a thermal runaway event, thus facilitating thermal control and management of the battery <NUM> to keep the temperature of the battery <NUM> within a desired range.

As mentioned above, <FIG> also shows a schematic of the example control system <NUM>. The control system <NUM> forms part of the cooling circuit with the first bus bar <NUM>. In the illustrated example, the control system <NUM> includes a reservoir <NUM> of the cooling fluid <NUM>, a supply line <NUM> coupled between the reservoir <NUM> and the inlet port <NUM> (<FIG>) on the housing <NUM>, a return line <NUM> coupled between the outlet port <NUM> (<FIG>) on the housing <NUM> and the reservoir <NUM>, a pump <NUM> coupled to the supply line <NUM>, and a controller <NUM> to control the pump <NUM> (e.g., turn the pump on or off and/or control the speed of the pump <NUM>). When the pump <NUM> is activated, the pump <NUM> pumps the first cooling fluid <NUM> through the supply line <NUM> from the reservoir <NUM> to the inlet port <NUM> (<FIG>) on the housing <NUM>. The first cooling fluid <NUM> flows through the inlet port <NUM> (<FIG>) and into the inlet port <NUM> (<FIG>) in the first bus bar <NUM>. The first cooling fluid <NUM> flows through the fluid channel <NUM> (<FIG>) in the first bus bar <NUM>. The first cooling fluid <NUM> then exits the outlet port <NUM> (<FIG>) in the first bar <NUM>. The first cooling fluid <NUM> flows through the outlet port <NUM> (<FIG>) on the housing <NUM> to the return line <NUM>, and through the return line <NUM> back into the reservoir <NUM>. As such, the first cooling fluid <NUM> is fluidly isolated from and separate from the second cooling fluid <NUM>. In some examples, the control system <NUM> includes a heat exchanger to cool the first cooling fluid <NUM> before returning to the battery <NUM>.

In examples disclosed, the controller <NUM> operates to activate and deactivate the pump <NUM> to maintain the battery <NUM> within a desired temperature range (e.g., below a first threshold and/or above a second threshold). Additionally or alternatively, the controller <NUM> can increase or decrease the power of the pump <NUM> to increase or decrease the flow rate of the first cooling fluid <NUM> through the first bus bar <NUM>. In some examples, the controller <NUM> can monitor a temperature of the battery <NUM> based on signals from a temperature sensor <NUM>. In some examples, the temperature sensor <NUM> is disposed in the cavity <NUM>. The temperature sensor <NUM> is communicatively coupled to the controller <NUM> via a wired or wireless connection. The controller <NUM> can activate/deactivate the pump <NUM> and/or increase/decrease the power to the pump <NUM> based on the temperature. When the controller <NUM> activates the pump <NUM>, the first cooling fluid <NUM> can circulate through the fluid channel <NUM> (<FIG>), which helps reduce the temperature of the first bus bar <NUM> and, thus, helps maintain the battery temperature within a desired temperature range. In some examples, if the pump <NUM> fails, the second cooling fluid <NUM> submerging the battery cells <NUM> in the cavity <NUM> of the battery housing <NUM> can still facilitate thermal management of the battery <NUM> to keep the temperature of the battery <NUM> within an operational temperature range. While the example control system <NUM> is disclosed in connection with the first bus bar <NUM>, the control system <NUM> (or a separate control system) can similarly control the pumping of cooling fluid through the second bus bar <NUM>.

<FIG> is a flowchart representative of an example method <NUM> that can be implemented by the example control system <NUM>. In particular, the method <NUM> of <FIG> can be implemented by instructions that are executed by the controller <NUM>. The controller <NUM> can be implemented by one or more digital circuit(s), logic circuits, programmable processor(s), programmable controller(s), graphics processing unit(s) (GPU(s)), digital signal processor(s) (DSP(s)), application specific integrated circuit(s) (ASIC(s)), programmable logic device(s) (PLD(s)) and/or field programmable logic device(s) (FPLD(s)). The method <NUM> is described in connection with pumping fluid through the first bus bar <NUM>. However, the method <NUM> can be similarly performed in connection with the second bus bar <NUM>.

Although the example method <NUM> is described with reference to the flowchart illustrated in <FIG>, many other methods can alternatively be used. For example, some of the blocks described herein can be changed, eliminated, or combined.

The example method starts with the pump <NUM> off or deactivated. At block <NUM>, the controller <NUM> determines the temperature of the battery <NUM> based on signals from the temperature sensor <NUM>. The battery temperature can be measured or determined continuously during the operation of the battery <NUM> or periodically over increments of time (e.g., every <NUM> seconds). At block <NUM>, the controller <NUM> compares the temperature to a threshold temperature. The threshold temperature can vary across battery types, use cases, and/or depending on the type(s) of cooling fluids used by the fluid circuit and/or to submerge the battery cells <NUM>. At block <NUM>, the controller <NUM> determines if the determined battery temperature exceeds the threshold temperature. In response to determining that the battery temperature exceeds the threshold temperature, the controller <NUM>, at block <NUM>, activates the pump <NUM> to pump the first cooling fluid <NUM> through the fluid channel <NUM> of the first bus bar <NUM> to reduce the temperature of the battery <NUM>. In contrast, if the battery temperature does not exceed the threshold temperature the pump <NUM> remains deactivated and control proceeds to block <NUM>.

At block <NUM>, the controller <NUM> determines the temperature of the battery <NUM> after the activation of the pump <NUM> at block <NUM>. At block <NUM>, the controller <NUM> compares the battery temperature to the temperature threshold. At block <NUM>, the controller <NUM> determines whether the battery temperature decreased, for example during the operation of the pump <NUM>, and returned to a temperature below the threshold temperature. In response to determining that the battery temperature has fallen below the threshold temperature, the controller <NUM>, at block <NUM>, deactivates the pump <NUM> to cease pumping of the cooling fluid through the fluid channel <NUM>. However, if controller <NUM> determines that the temperature is above the threshold, the controller <NUM> keeps the pump <NUM> activated, and control proceeds back to block <NUM>. After block <NUM>, the example method <NUM> can end or control can proceed back to block <NUM> and the example <NUM> can repeat.

From the foregoing, it will be appreciated that example methods, apparatus and articles of manufacture have been disclosed that enable thermal management of batteries that are advantageous to known methods and apparatus. The methods and apparatus disclosed herein provide solutions that address the maintenance of batteries within operating temperature ranges while also considering energy capacity and weight characteristic improvements in batteries. Such advantages can not only extend the cycle life of batteries but can also mitigate risks of battery overheating and thus thermal runaway events. The examples disclosed herein improve heat transfer and cell temperature uniformity.

Example methods, apparatus, and articles of manufacture for thermal management of batteries are been disclosed herein. Also provided are the following illustrative, non-exhaustive example of further non-claimed embodiments that are compatible with the claimed subject matter:
In the claimed battery, the second cooling fluid may partially fill the cavity such that an air gap is formed between a top surface of the second cooling fluid and a top of the housing.

In the claimed battery, the first cooling fluid forms the cooling circuit in the bus bar, and the cooling circuit may receive the second cooling fluid to reduce a temperature of the bus bar.

The second cooling fluid may be fluidly isolated from the first cooling fluid in the cavity.

The housing may include a wall with a port, wherein the battery may further include a pressure release valve in the port.

Claim 1:
A battery (<NUM>) comprising:
a housing (<NUM>) defining a cavity (<NUM>);
a plurality of battery cells (<NUM>) disposed in the cavity (<NUM>) of the housing (<NUM>), the battery cell (<NUM>) having a first terminal (<NUM>) and a second terminal (<NUM>);
a first bus bar (<NUM>) disposed in the cavity (<NUM>) of the housing (<NUM>), the first bus bar (<NUM>) coupled to the first terminal (<NUM>), a first fluid channel (<NUM>) formed in the first bus bar (<NUM>);
a second bus bar (<NUM>) disposed in the cavity (<NUM>) of the housing (<NUM>), the second bus bar (<NUM>) coupled to the second terminal (<NUM>) of the battery cell (<NUM>), a second fluid channel (<NUM>) formed in the second bus bar (<NUM>), the second bus bar (<NUM>) disposed parallel to the first bus bar (<NUM>);
the first and second fluid channels (<NUM>, <NUM>) to receive a cooling fluid (<NUM>) to cool the first and second bus bars (<NUM>, <NUM>) respectively and reduce a temperature of the battery (<NUM>); and
a central spine (<NUM>) disposed between the first and second bus bars (<NUM>, <NUM>), the first and second bus bars (<NUM>, <NUM>) electrically coupled to the central spine (<NUM>), wherein the central spine (<NUM>) includes circuitry to measure voltage of the battery cell (<NUM>).