Battery system and flying vehicle

Abstract

Provided is a battery system comprising: a battery pack having a thickness that changes due to charging and discharging; and a restraining member for restraining the battery pack, the restraining member having a configuration such that, if the pressure applied to the battery pack by the restraining member exceeds a predetermined pressure, because of a change in thickness due to charging and discharging of the battery pack, the restraining member becomes damaged and the restraint of the battery pack is released. The restraining member may restrain the battery pack by means of two plate-like members sandwiching the battery pack along the direction of the thickness.

Description

Battery system and flying vehicle

[0001] The present invention relates to a battery system and an aircraft.

[0002] Patent Document 1 describes a lithium-ion battery in which a plurality of stacked battery cells are sandwiched between metal plates and constrained using metal bands, thereby applying constraining pressure to the battery cells in the stacking direction. [Prior Art Documents] [Patent Documents] [Patent Document 1] JP 2022-075152 A General disclosure

[0003] (Means for Solving the Problem) According to one embodiment of the present invention, there is provided a battery system. The battery system may include a battery pack whose thickness changes due to charging and discharging. The battery system may include a restraining member that restrains the battery pack. The restraining member may be configured to break and release the restraint on the battery pack when a pressure applied to the battery pack by the restraining member due to a change in thickness due to charging and discharging of the battery pack exceeds a predetermined pressure.

[0004] In the battery system, the restraining member may restrain the battery pack via two plate-shaped members that sandwich the battery pack along the thickness direction. In the battery system, the restraining member may directly restrain the battery pack. In any of the battery systems, a material of at least one of the two plate-shaped members may include reinforced plastic.

[0005] In any of the battery systems described above, the restraining member may be annular. The restraining member may rupture when pressure applied to the battery pack by the restraining member exceeds the predetermined pressure. The battery pack may be a lithium metal battery. The material of the restraining member may be organic fiber. The restraining member may be a band made of aramid fiber.

[0006] In any of the battery systems described above, the restraining member may have a band portion that wraps around the battery pack and a fixing portion that fixes different positions of the band portion together. The restraining member may be configured so that the fixing by the fixing portion is released when pressure applied to the battery pack by the restraining member exceeds the predetermined pressure. The fixing portion may include a connecting portion, and the connecting portion may be formed of a material that is different from and weaker than other portions of the fixing portion. The connecting portion may be formed so that the cross-sectional area of ​​the fixing portion, taken along a cross section intersecting the circumferential direction of the restraining member, is smaller than that of other portions of the fixing portion.

[0007] In any of the battery systems described above, the battery pack may have a characteristic that performance improves as the applied pressure increases up to a first pressure, and that performance decreases when a pressure greater than the first pressure is applied. The predetermined pressure may be a pressure determined based on the first pressure. The predetermined pressure may be a pressure obtained by multiplying the first pressure by a predetermined ratio greater than 1.

[0008] In any of the battery systems described above, the battery pack may include a battery cell. The battery cell may include a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators stacked alternately. The battery cell may include a bag-shaped member containing the plurality of positive electrodes, the plurality of negative electrodes, and the plurality of separators. The bag-shaped member may have a size that allows the stack of the plurality of positive electrodes, the plurality of negative electrodes, and the plurality of separators to be released and separated from each other after the pressure applied to the battery pack by the restraining member exceeds the predetermined pressure due to a change in thickness caused by charging and discharging of the battery pack, causing the restraining member to break and releasing the restraint of the battery pack. The bag-shaped member may have an aluminum laminate pouch structure.

[0009] In any of the battery systems described above, the battery pack may have a plurality of units arranged side by side in the thickness direction. Each of the plurality of units may include a plurality of the battery cells. The battery system may include a battery management system (BMS) unit. The battery system may include flexible printed circuits (FPCs) connected to the BMS unit. Each of the plurality of units may be connected to the FPC. The FPC may be configured to break due to a force applied between the plurality of units when a change in thickness due to charging and discharging of the battery pack causes pressure applied to the battery pack by the restraining members to exceed the predetermined pressure, causing the restraining members to release the battery pack from restraint.

[0010] In any of the battery systems described above, the FPC may include current wires and voltage wires that electrically connect the BMS unit and the battery pack. The FPC may include a film portion that covers the current wires and the voltage wires. The film portion may have a breaking portion that breaks due to a force applied between the multiple units when the battery pack is released from the restraining member. The breaking portion may have a notch shape. The breaking portion may have a perforation shape. The breaking portion may be made of a different material from the remaining portion of the FPC.

[0011] According to one embodiment of the present invention, there is provided an aircraft including the battery system and a thrust generating device that generates thrust using the electrical energy stored in the battery system.

[0012] The above summary of the invention does not list all of the necessary features of the present invention, and subcombinations of these features may also constitute inventions.

[0013] 1A and 1B are schematic diagrams showing an example of a battery system 10. 1A and 1B are schematic diagrams showing an example of a restraining member 200. 1A and 1B are schematic diagrams showing another example of a restraining member 200. 1A and 1B are schematic diagrams showing an example of a relationship between battery performance and pressure. 1A and 1B are schematic diagrams showing an example of a battery cell 120. 1A and 1B are schematic diagrams showing an example of a battery system 10. 1A and 1B are schematic diagrams showing an example of a HAPS 700 equipped with the battery system 10.

[0014] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention as claimed. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0015] Existing battery packs typically use robust materials such as aluminum and CERP (Carbon Fiber Reinforced Plastics) as components for the cases housing the battery pack. However, using such cases poses challenges in ensuring the functionality and safety of the battery pack. Even if the battery pack's thickness and internal pressure increase excessively due to expansion of the internal cells resulting from charging and discharging, it is difficult to stop battery operation by controlling the pressure because the robust material used for the case makes it difficult. Furthermore, to avoid the risk of malfunctions or accidents such as abnormally high temperatures and fires, a mechanism is required that can quickly detect cell degradation, cut off internal current, and stop the battery pack's function. The battery system 10 according to this embodiment has a mechanism that semi-automatically releases cell constraints, changes the pack structure, and cuts off current when a specific pressure is generated inside the battery pack, for example.

[0016] 1 is a schematic diagram of an example of a battery system 10. The battery system 10 includes a battery pack 100 and a restraining member 200.

[0017] The battery pack 100 is a pack of batteries. The battery pack 100 according to this embodiment has a characteristic that its thickness changes with charge and discharge, and that its performance improves as the applied pressure increases up to a certain pressure, but decreases when the applied pressure exceeds the certain pressure. The battery pack 100 includes one or more batteries.

[0018] 1 , the battery pack 100 has a plurality of units 110, and each of the plurality of units 110 includes a plurality of battery cells 120. Note that the battery pack 100 may have a single unit 110 rather than a plurality of units 110. Each of the plurality of units 110 may include a single battery cell 120 rather than a plurality of battery cells 120.

[0019] The battery pack 100 may be any type of battery as long as it has the characteristics that its thickness changes with charging and discharging, that its performance improves with increasing pressure up to a certain pressure, and that its performance decreases when pressure greater than the certain pressure is applied, For example, the battery pack 100 is a lithium metal battery.

[0020] The restraining member 200 restrains the battery pack 100. In the example shown in Fig. 1 , the restraining member 200 restrains the battery pack 100 via two plate-shaped members 140 that sandwich the battery pack 100 along the thickness direction. The restraining member 200 may also restrain the battery pack 100 directly without using the plate-shaped members 140.

[0021] 1 shows an example in which the battery system 10 includes three restraining members 200, each of which is spaced apart, but the number and arrangement of the restraining members 200 are not limited to this. For example, the battery system 10 may include one or two restraining members 200, or may include four or more restraining members 200. When the battery system 10 includes multiple restraining members 200, the spacing between the multiple restraining members 200 may be uniform. The spacing between the multiple restraining members 200 does not have to be uniform. The multiple restraining members 200 may also be arranged without spacing between them.

[0022] As the battery pack 100 is repeatedly charged and discharged, the thickness of the battery pack 100 gradually increases. Therefore, if the battery pack 100 is repeatedly charged and discharged while restrained by the restraining member 200, the internal pressure of the battery pack 100 increases. The restraining member 200 is configured to break when the pressure applied to the battery pack 100 due to the change in thickness caused by charging and discharging of the battery pack 100 exceeds a predetermined pressure, thereby releasing the restraint of the battery pack 100. This makes it possible to prevent the internal pressure of the battery pack from becoming excessive. As a result, it becomes possible to prevent a short circuit of the battery pack 100 and the resulting fire, etc.

[0023] By having the restraining member 200 restrain the battery pack 100 via the two plate-like members 140, the force with which the restraining member 200 restrains the battery pack 100 can be applied more uniformly to the battery pack 100. Therefore, compared to a case in which the plate-like members 140 are not present, local deformation of the battery pack 100 and the resulting failure or performance degradation of the battery pack 100 can be suppressed. When the plate-like members 140 are not present, the possibility of local deformation of the battery pack 100 and the resulting failure or performance degradation of the battery pack 100 increases compared to a case in which the plate-like members 140 are present. However, depending on the configuration of the battery pack 100, this possibility may not increase significantly, and there is an advantage in that the overall weight of the battery pack 100 can be reduced.

[0024] The plate-shaped member 140 may be made of any material as long as it has a relatively smooth surface that can be in uniform contact with the battery pack 100 and is made of a relatively rigid material. The plate-shaped member 140 may be made of, for example, metal, such as iron or aluminum. As another example, the plate-shaped member 140 may be made of reinforced plastic, such as fiber reinforced plastics (FRP). This allows the total weight of the battery system 10 to be reduced while ensuring the strength and rigidity of the plate-shaped member 140, thereby improving the weight-energy density of the battery system 10.

[0025] An interfering material such as rubber may be disposed between the plate-shaped member 140 and the battery pack 100. For example, a plate-shaped rubber material may be disposed on the surface of the plate-shaped member 140 that comes into contact with the battery pack 100.

[0026] The battery system 10 may include a BMS unit 150 and an FPC 160. The BMS unit 150 is a system that performs safety control of the battery pack 100. For example, the BMS unit 150 monitors the voltage and current values ​​of the battery pack 100 and stops charging and discharging of the battery pack 100 when an abnormality is detected. The BMS unit 150 may monitor the voltage and current values ​​during charging and discharging for one or more units included in the battery pack 100 and determine whether or not an abnormality exists based on the voltage and / or current values ​​of each unit. The BMS unit 150 may determine whether or not an abnormality exists based on the amount of change per unit time in the voltage value of each unit 110 and / or the amount of change per unit time in the current value of each unit. If the BMS unit 150 determines that an abnormality exists in any unit, it may stop charging and discharging of the entire battery system 10. When the BMS unit 150 determines that there is an abnormality in each unit, it may stop charging and discharging for each unit 110 included in the battery system 10 .

[0027] The FPC 160 has electrical wiring that electrically connects the battery pack 100 and the BMS unit 150. The FPC 160 has a voltage line that connects the voltage output of the battery pack 100 to the voltage input of the BMS unit 150, and a current line that connects the current output of the battery pack 100 to the current input of the BMS unit 150. The FPC 160 may have electronic components such as an IC chip, and may have electrical wiring other than voltage lines and current lines. When the battery pack 100 has multiple units 110, the FPC may have electrical wiring that electrically connects each of the units 110 to the BMS unit 150.

[0028] FIG. 2 schematically illustrates an example of a restraining member 200. The restraining member 200 may have any configuration as long as it ruptures when the pressure applied to the battery pack 100 by the restraining member 200 exceeds a predetermined pressure. The restraining member 200 illustrated in FIG. 2 is annular and ruptures when the pressure applied to the battery pack 100 by the restraining member 200 exceeds a predetermined pressure. The material, width, and thickness of the restraining member 200 are selected so that the restraining member 200 ruptures when the pressure applied to the battery pack 100 by the restraining member 200 exceeds the predetermined pressure. The material of the restraining member 200 may be, for example, organic fiber. The organic fiber may be, for example, polyester fiber, nylon fiber, rayon fiber, polyketone fiber, polyamide fiber, or the like. By using organic fiber as the material of the restraining member 200, the total weight of the battery system 10 can be reduced while ensuring the strength and rigidity of the restraining member 200 compared to when a metal is used, thereby improving the weight-energy density of the battery system 10. The polyamide fiber may be, for example, aramid fiber. By using aramid fiber as the material for the restraint member 200, the strength and rigidity of the restraint member 200 can be ensured to be higher than when metal or other organic fibers are used, while the total weight of the battery system 10 can be reduced, thereby further improving the weight-energy density of the battery system 10.

[0029] The breaking strength of restraining member 200 can be adjusted so that restraining member 200 is configured to rupture when the pressure applied to battery pack 100 exceeds a predetermined pressure. For example, the force that restraining member 200 receives from battery pack 100 is calculated from the predetermined pressure and the area of ​​the surface where restraining member 200 and battery pack 100 come into contact, and the number of restraining members 200 to be attached to battery pack 100 and the breaking strength of each restraining member 200 are adjusted based on this force.

[0030] The breaking strength of each restraint member 200 can be adjusted by increasing or decreasing the cross-sectional area of ​​the restraint member 200 intersecting the circumferential direction and / or by increasing or decreasing the breaking strength (breaking stress) per cross-section of the restraint member 200 intersecting the circumferential direction. In this embodiment, the case where the material of the restraint member 200 is organic fiber will be mainly described. For example, the cross-sectional area of ​​the restraint member 200 intersecting the circumferential direction can be adjusted by increasing or decreasing the number of times the organic fiber is wound. For example, the breaking stress of the restraint member 200 can be adjusted by changing the breaking stress of the organic fiber. For example, the breaking stress of the organic fiber can be changed by selecting the type and composition of the organic fiber, or by post-processing such as bending or aging the organic fiber.

[0031] FIG. 3 schematically illustrates another example of the restraining member 200. Unlike the example illustrated in FIG. 2 , the restraining member 200 in the example illustrated in FIG. 3 includes a band portion 210 that wraps around the battery pack 100 and a fixing portion 220 that fixes different positions of the band portion 210 together. The fixing of the restraining member 200 by the fixing portion 220 is released when the pressure applied to the battery pack 100 by the restraining member 200 exceeds a predetermined pressure. The structure, shape, and material of the fixing portion 220 may be any structure, shape, and material as long as the fixing by the fixing portion 220 is released when the pressure applied to the battery pack 100 by the restraining member 200 exceeds the predetermined pressure. For example, the structure and shape of the fixing portion 220 may be a structure and shape that imitates the structure and shape of a typical belt buckle. For example, the material of the fixing portion 220 may be metal, but is not limited thereto. For example, the material of the fixing portion 220 may be non-metallic and may be a relatively strong plastic, such as FRP.

[0032] The structure, shape and material of the band portion 210 may be the same as the structure, shape and material of the restraint member 200 in the example shown in Fig. 2, except for the connection portion 230 between the band portion 210 and the fixed portion 220. A description thereof will be omitted.

[0033] For example, when the pressure applied to battery pack 100 by restraining member 200 exceeds a predetermined pressure, restraining member 200 may be released from fixation by fixing portion 220 by causing internal breakage of fixing portion 220, but this is not limited to this. As another example, restraining member 200 may be released from fixation by fixing portion 220 by causing breakage of either connection portion 230 between band portion 210 and fixing portion 220. By configuring restraining member 200 from band portion 210 and fixing portion 220, the task of attaching restraining member 200 to battery pack 100 is simplified, and the breaking strength of restraining member 200 is easily adjusted, which is expected to improve the accuracy of breaking strength adjustment.

[0034] 3 , for example, fixed portion 220 may break at connecting portion 222. Connecting portion 222 may be formed of a different material, for example, having a lower strength than the other portions of fixed portion 220. As another example, connecting portion 222 may be formed of the same material as the other portions of fixed portion 220, and the cross-sectional area of ​​a cross section intersecting the circumferential direction of fixed portion 220 may be smaller than the other portions of fixed portion 220. Configuring fixed portion 220 to include connecting portion 222 makes it easier to adjust the breaking strength of restraint member 200, and is expected to improve the accuracy of breaking strength adjustment.

[0035] FIG. 4 schematically illustrates an example of the relationship between the pressure applied to the battery pack 100 and the battery performance of the battery pack 100. The vertical axis of the graph in FIG. 4 represents the battery performance of the battery pack 100, and the horizontal axis represents the confinement pressure of the battery pack 100. The battery performance may be an index obtained by analyzing the results of various tests on the battery pack 100, such as a cycle test or a storage test. For example, the cycle life of the battery pack 100 obtained from the cycle test of the battery pack 100 may be an example of the battery performance of the battery pack 100. When performing a cycle test of the battery pack 100, the voltage and current values ​​of the battery pack 100 are measured while repeatedly charging and discharging the battery pack 100 under specific conditions, and the capacity retention rate, Coulomb efficiency, and other indices of the battery pack 100 are calculated from the obtained voltage and current values. As the battery pack 100 is repeatedly charged and discharged, the capacity retention rate, Coulomb efficiency, and other indices of the battery pack 100 gradually decrease. The number of charge / discharge cycles at which one or more of the indices such as capacity retention rate and coulomb efficiency falls below a preset threshold may be taken as the cycle life [number of cycles] of the battery.

[0036] For example, by changing the pressure conditions for restraining the battery pack 100 and performing a cycle test on the battery, the relationship between the battery performance and the pressure can be obtained as shown in Fig. 4. In the example shown in Fig. 4, when the applied pressure is a peak pressure P １ The higher the applied pressure, the better the battery performance. １ If a larger pressure is applied, the battery performance will decrease. The pressure at which the restraining member 200 breaks is the peak pressure P １ This allows the battery pack 100 to be effectively used until the battery performance of the battery pack 100 falls below a predetermined standard as the restraining pressure increases, while allowing the restraint of the battery pack 100 to be released before the battery performance falls below the predetermined standard, thereby making it possible to prevent a short circuit of the battery pack 100 and the resulting fire, etc. For example, the pressure at which the restraining member 200 breaks is determined based on the peak pressure P １ , a ratio R greater than 1 １ The upper limit pressure P ULThis makes it possible to effectively use the battery pack 100 under practical pressure conditions under which the battery pack 100 can be effectively used even after the battery performance of the battery pack 100 falls below its peak as the restraining pressure increases, while preventing short circuits in the battery pack 100 and the resulting fires and the like. １ may be.

[0037] Peak pressure P １ may be an example of the first pressure. UL may be an example of a predetermined pressure at which the restraining member 200 breaks. １ may be an example of a predetermined ratio. １ can be any ratio greater than 1. １ may be 1.1, 1.2, 1.3, 1.4, 1.5, etc.

[0038] A test for obtaining the relationship between battery performance and pressure can be performed, for example, using a device that applies a variable load to the battery pack 100 along the thickness direction of the battery pack 100 and measures the load during compression using a load cell or other means. The measured load can be divided by the contact area between the battery pack and the flat plate to obtain the pressure applied to the battery pack 100, i.e., the confinement pressure of the battery pack 100. By performing the cycle test described above using such a device, the relationship between battery performance and pressure, as shown in FIG. 4, can be obtained. The first pressure and the predetermined ratio greater than 1 may depend on various factors, such as the type, structure, size, environmental conditions, and operating conditions of the battery pack. Therefore, it is desirable to identify the first pressure and the predetermined ratio for each target battery pack, environmental conditions, and operating conditions using the above-described tests and / or various simulation techniques.

[0039] FIG. 5 schematically illustrates an example of a battery cell 120. In FIG. 5 , the structure of the battery cell 120 is described in a state in which the battery pack 100 is restrained by a restraining member 200. The battery cell 120 includes a plurality of positive electrodes 122, a plurality of negative electrodes 124, and a plurality of separators 126, which are alternately stacked. The battery cell 120 includes a pouch-shaped member 128 that contains the plurality of positive electrodes 122, the plurality of negative electrodes 124, and the plurality of separators 126. The battery cell 120 may include a positive electrode lead 132 that outputs current from the battery cell 120 and a negative electrode lead 134 that outputs electrons from the battery cell 120. The battery cell 120 includes an electrolyte.

[0040] The electrical connection between the multiple positive electrodes 122 and the positive electrode lead 132 may be such that each positive electrode 122 and each positive electrode lead 132 are connected in parallel, or may be otherwise, and is not limited thereto. The electrical connection between the multiple negative electrodes 124 and the negative electrode lead 134 may be such that each negative electrode 124 and each negative electrode lead 134 are connected in parallel, or may be otherwise, and is not limited thereto. For example, the multiple positive electrodes 122 and the multiple negative electrodes 124 stacked alternately within the battery cell 120 may be alternately connected in series, with the positive electrode 122 at the end of the series structure connected to the positive electrode lead 132 and the negative electrode 124 at the opposite end of the series structure connected to the negative electrode lead 134.

[0041] Fig. 6 schematically illustrates an example of a battery cell 120. In the example illustrated in Fig. 6, the state of the battery cell 120 after the restraining member 200 breaks and the restraint of the battery pack 100 is released due to the pressure applied to the battery pack 100 by the restraining member 200 exceeding a predetermined pressure caused by a change in thickness due to charging and discharging of the battery pack 100 will be described. Each component of the battery cell 120 is the same as the example illustrated in Fig. 5, and a description thereof will be omitted.

[0042] Once the restraining member 200 is broken and the battery pack 100 is released from restraint, it is conceivable that the stack of the multiple positive electrodes 122, the multiple negative electrodes 124, and the multiple separators 126 may be easily released due to the generation of gas 136 associated with subsequent charging and discharging. In this case, contact between the electrodes and the electrolyte is hindered, making it difficult to ensure ion conduction paths, and charging and discharging of the battery cell 120 may be easily stopped. In the example shown in FIG. 6 , the bag-shaped member 128 has a size that allows the stack of the multiple positive electrodes 122, the multiple negative electrodes 124, and the multiple separators 126 to be released and separated from each other. This makes it easier for the stack of the multiple positive electrodes 122, the multiple negative electrodes 124, and the multiple separators 126 to be released from each other after the restraining member 200 is broken and the battery pack 100 is released from restraint, thereby more reliably stopping charging and discharging of the battery cell 120.

[0043] The bag-shaped member 128 may be made of any material or have any structure as long as it has the above-mentioned size. As an example, the bag-shaped member 128 may have an aluminum laminate pouch structure.

[0044] FIG. 7 schematically illustrates an example of a battery system 10. In the example illustrated in FIG. 7, a battery pack 100 includes multiple units 110 arranged side by side in the thickness direction, and each of the multiple units 110 includes multiple battery cells 120. The battery system 10 includes a BMS unit 150 and an FPC 160 connected to the BMS unit 150. Each of the multiple units 110 is connected to the FPC 160. The FPC 160 is configured to break due to the force applied between the multiple units 110 when the pressure applied to the battery pack 100 by the restraining member 200 exceeds a predetermined pressure due to a change in thickness caused by charging or discharging the battery pack 100, causing the restraining member 200 to release the restraint of the battery pack 100. This allows for more reliable stopping of charging or discharging of the battery cells 120 after the restraining member 200 is broken and the restraint of the battery pack 100 is released.

[0045] In the battery system 10, adjacent units 110 come into contact with each other and exert a pressing force on each other, and the sum of these forces is balanced with the force with which the restraining member 200 restrains the battery pack 100. When the restraining member 200 releases the battery pack 100 from being restrained, the adjacent units 110 come into contact with each other and the pressing force on each other is released. The thickness, shape, material, etc. of the FPC 160 are appropriately adjusted so that the FPC 160 breaks due to this force. This makes it possible to more reliably stop charging and discharging the battery cells 120 after the restraining member 200 breaks and the restraint on the battery pack 100 is released.

[0046] When the restraining member 200 is broken and the restraint of the battery pack 100 is released, the thickness of the unit 110 increases due to gas generation and other factors associated with subsequent charging and discharging. As a result, adjacent units 110 come into contact with each other and exert a pressing force against each other. The thickness, shape, material, and the like of the FPC 160 may be appropriately adjusted so that this force causes the FPC 160 to break. This makes it possible to more reliably stop charging and discharging of the battery cells 120 after the restraining member 200 is broken and the restraint of the battery pack 100 is released.

[0047] As another example, the battery system 10 may further include a configuration that directly acts on the FPC 160 to break the FPC in conjunction with damage to the restraining member 200. This makes it possible to more reliably stop charging and discharging the battery cells 120 after the restraining member 200 is damaged and the restraint of the battery pack 100 is released.

[0048] The FPC 160 may include current wires and voltage wires that electrically connect the BMS section 150 and the battery pack 100, and a film section that covers the current wires and voltage wires. The film section may have a breaking portion 162 that breaks due to a force applied between the multiple units 110 when the battery pack 100 is released from the restraint by the restraint member 200. The position and shape of the breaking portion 162 on the FPC 160 may be any position and may be any shape, as long as the breaking portion 162 is configured so that the FPC 160 breaks due to a force applied between the multiple units 110 when the battery pack 100 is released from the restraint by the restraint member 200. As an example, as shown in FIG. 7 , the position of the break portion 162 on the FPC 160 may be, but is not limited to, a position close to the base of each unit of the FPC 160, a position connecting each unit of the FPC 160, and / or a position close to the base of the BMS section 150 of the FPC 160. As an example, as shown in FIG. 7 , the shape of the break portion 162 may be a notch shape. The direction of the notch may be the lateral direction of the FPC 160 as shown in FIG. 7 , or may be the thickness direction of the FPC 160. The shape of the break portion 162 is not limited to a notch shape. As another example, the break portion 162 may be perforated. Only the break portion 162 may be made of a different material. This separates the functions of the part of the FPC 160 that breaks when subjected to a specified force from the part that does not, ensuring the durability and electrical conductivity of the FPC 160, while more reliably stopping charging and discharging of the battery cell 120 after the restraining member 200 breaks and the restraint on the battery pack 100 is released.

[0049] The multiple units 110 of the battery pack 100 may be connected to the BMS unit 150 in parallel with each other via the FPC 160. In the example shown in FIG. 7 , for example, the FPC may rupture at one of the multiple rupture portions 162, which is located near the base of one of the multiple units 110. In this case, the current line of the one unit 110 may be cut, and charging and discharging of the one unit 110 may be stopped. The BMS unit 150 may stop charging and discharging of the other units 110 based on changes in the current value of the one unit 110. This makes it possible to more reliably prevent short circuits in the battery pack 100 and resulting fires. The BMS unit 150 may stop charging and discharging of only the one unit 110 while continuing charging and discharging of the other units 110. This allows the charging and discharging capabilities of the other units 110 in the battery system 10 that have not been confirmed to be abnormal to be kept available, minimizing the impact on the remaining power amount, while stopping only the unit 110 that has been confirmed to be abnormal, making it possible to more reliably prevent short circuits in the unit 110 and resulting fires, etc.

[0050] In a similar case, if the voltage line of one of the units 110 is cut, the BMS unit 150 may stop charging and discharging of the one unit 110 based on a change in the voltage value of the one unit 110 and may stop charging and discharging of the other units 110. This makes it possible to more reliably prevent a short circuit of the battery pack 100 and a resulting fire, etc. from occurring. The BMS unit 150 may stop charging and discharging of only the one unit 110 while continuing charging and discharging of the other units 110. This keeps the charging and discharging capabilities of the other units 110 in the battery system 10 that have not been found to be abnormal available, minimizing the impact on the remaining energy, and by stopping only the unit 110 in which an abnormality has been found, it is possible to more reliably prevent a short circuit of the unit 110 and a resulting fire, etc. from occurring.

[0051] All of the multiple units 110 of the battery pack 100 may be connected in series by the FPC 160 and connected to the BMS unit 150. In the example shown in FIG. 7 , for example, the FPC 160 breaks at one of the multiple broken portions 162. In this case, the current line near the broken portion 162 is cut, and charging and discharging of all of the multiple units 110 in the same battery system 10 is stopped. This stops the battery system 10 without the intervention of the BMS unit 150. Therefore, even if a malfunction occurs in the anomaly detection function or the like of the BMS unit 150, it is possible to more reliably prevent a short circuit in the battery system 10 and the resulting fire, etc., beforehand, without relying on electronic control by these functions.

[0052] In a similar case, if the voltage line near the broken portion 162 is cut, the BMS unit 150 may stop charging and discharging of all of the multiple units 110 in the same battery system 10 based on a change in the voltage value of the battery pack 100. Charging and discharging of the units 110 other than the one unit 110 may also be stopped. This makes it possible to more reliably prevent a short circuit in the battery pack 100 and the resulting fire, etc.

[0053] 8 schematically shows an example of a HAPS 700 equipped with a battery system 10. The HAPS 700 is an air vehicle that provides wireless communication services to user terminals 30 within a communication area 704 formed by irradiating a beam 702 toward the ground. The HAPS 700 may be an example of an air vehicle that includes the battery system 10 and a thrust generating device that generates thrust using electrical energy stored in the battery system 10.

[0054] HAPS 700 includes a fuselage 710, a center section 720, propellers 730, pods 740, and solar panels 750. The fuselage 710 has wing sections 712. The wing sections 712 include a left wing section 714 and a right wing section 716.

[0055] For example, a battery system 10 is disposed inside the wing section 712. The electric energy stored in the battery system 10 is utilized by each component of the HAPS 700. For example, the electric energy stored in the battery system 10 is utilized by the motor of the propeller 730 that generates propulsion force. As a specific example, a plurality of battery systems 10 connected in parallel are disposed inside the wing section 712. Of the plurality of battery systems 10, the left-side plurality of battery systems 10 may be disposed in the left wing section 714, and the right-side plurality of battery systems 10 may be disposed in the right wing section 716. The electric power discharged by the plurality of battery systems 10 is utilized by each component of the HAPS 700. For example, the electric power discharged by the plurality of battery systems 10 is utilized by the motor of the propeller 730.

[0056] A flight control unit 722 and a communication control unit 724 are disposed within the central unit 720. The flight control unit 722 controls the flight of the HAPS 700 using power discharged by the multiple battery systems 10. The communication control unit 724 controls the communication of the HAPS 700 using power discharged by the multiple battery systems 10.

[0057] The flight control unit 722 controls the flight of the HAPS 700, for example, by controlling the rotation of the propeller 730. The flight control unit 722 may also control the flight of the HAPS 700 by changing the angles of flaps or elevators (not shown). The flight control unit 722 may include various sensors, such as a positioning sensor such as a GPS sensor, a gyro sensor, and an acceleration sensor, and may manage the position, movement direction, and movement speed of the HAPS 700.

[0058] The communication control unit 724 forms a communication area 704 on the ground using a service link (SL) antenna. The communication control unit 724 forms a service link with a terrestrial user terminal 30 using the SL antenna. The SL antenna may be a multi-beam antenna. The communication area 704 may be a multi-cell.

[0059] The communication control unit 724 may use a FL (Feeder Link) antenna to form a feeder link with the terrestrial gateway 40. The communication control unit 724 may access the network 20 via the gateway 40.

[0060] The communication control unit 724 may use a satellite communication antenna to communicate with the communication satellite 50. The communication control unit 724 may access the network 20 via the communication satellite 50 and the satellite communication station 60.

[0061] The user terminal 30 may be any communication terminal capable of communicating with the HAPS 700. For example, the user terminal 30 may be a mobile phone such as a smartphone. The user terminal 30 may also be a tablet terminal, a PC (Personal Computer), or the like. The user terminal 30 may also be a so-called Internet of Things (IoT) device. The user terminal 30 may include anything that falls under the so-called Internet of Everything (IoE).

[0062] The HAPS 700 relays communications between the network 20 and the user terminal 30, for example, via a feeder link or a communications satellite 50 and a service link. The HAPS 700 may provide wireless communication services to the user terminal 30 by relaying communications between the user terminal 30 and the network 20.

[0063] The network 20 includes a mobile communication network. The mobile communication network may conform to any of the following communication methods: Long Term Evolution (LTE), 5th Generation (5G), 3rd Generation (3G), and 6th Generation (6G) or later. The network 20 may include the Internet.

[0064] For example, the HAPS 700 transmits data received from a user terminal 30 within the communication area 704 to the network 20. Furthermore, when the HAPS 700 receives data addressed to a user terminal 30 within the communication area 704 via the network 20, the HAPS 700 transmits the data to the user terminal 30.

[0065] HAPS 700 maintains a communication area 704 in a specific area on the ground while circulating along a predetermined flight path in the stratosphere, for example. HAPS 700 stores power generated by solar panels 750 in multiple battery systems 10 during the day and maintains stratospheric flight at night by using the power of multiple battery systems 10. HAPS 700 ascends and stores potential energy while charging multiple battery systems 10 during the day, and maintains stratospheric flight at night by gently descending and appropriately operating propellers 730 and the like using the power of the battery systems 10.

[0066] The management device 800 manages a plurality of HAPSs 700. The management device 800 may communicate with the HAPSs 700 via the network 20 and the gateway 40. The management device 800 may communicate with the HAPSs 700 via the network 20, the satellite communication station 60, and the communication satellite 50.

[0067] The management device 800 controls the HAPS 700 by transmitting instructions. The management device 800 may cause the HAPS 700 to circle above a target area on the ground so that the target area is covered by the communication area 704. For example, while flying in a circular orbit above the target area, the HAPS 700 maintains a feeder link with the gateway 40 by adjusting the direction of orientation of the FL antenna, and maintains coverage of the target area by the communication area 704 by adjusting the direction of orientation of the SL antenna.

[0068] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0069] It should be noted that the order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and that the processes can be performed in any order unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that the processes must be performed in this order.

[0070] 10 Battery system, 20 Network, 30 User terminal, 40 Gateway, 50 Communication satellite, 60 Satellite communication station, 100 Battery pack, 110 Unit, 120 Battery cell, 122 Positive electrode, 124 Negative electrode, 126 Separator, 128 Bag-shaped member, 132 Positive electrode lead, 134 Negative electrode lead, 136 Gas, 140 Plate-shaped member, 150 BMS section, 160 FPC, 162 Fracture portion, 200 Restraint member, 210 Band portion, 220 Fixed portion, 222 Connection portion, 230 Connection portion, 700 HAPS, 702 Beam, 704 Communication area, 710 Airframe, 712 Wing portion, 714 Left wing portion, 716 Right wing portion, 720 Center portion, 722 Flight control unit, 724 Communication control unit, 730 Propeller, 740 Pod, 750 Solar panel, 800 Management device

Claims

1. A battery system comprising: a battery pack whose thickness changes upon charging and discharging; and a restraining member that restrains the battery pack, the restraining member being configured to break and release the restraint of the battery pack when the pressure applied to the battery pack by the restraining member exceeds a predetermined pressure due to the change in thickness of the battery pack upon charging and discharging.

2. The battery system according to claim 1, wherein the restraining member restrains the battery pack via two plate-like members that sandwich the battery pack along the thickness direction.

3. The battery system according to claim 1 or 2, wherein the restraining member is annular and breaks when the pressure applied to the battery pack by the restraining member exceeds the predetermined pressure.

4. The battery system according to claim 3, wherein the battery pack is a lithium metal battery and the restraining member is made of aramid fiber.

5. The battery system according to any one of claims 1 to 4, wherein the restraining member has a band portion that wraps around the battery pack and a fixing portion that fixes different positions of the band portion, and the fixing by the fixing portion is released when the pressure applied to the battery pack by the restraining member exceeds the predetermined pressure.

6. The battery system according to any one of claims 1 to 5, wherein the battery pack has a characteristic that its performance improves as the applied pressure increases up to a first pressure, and its performance deteriorates when a pressure stronger than the first pressure is applied, and the predetermined pressure is a pressure determined based on the first pressure.

7. The battery system according to claim 6, wherein the predetermined pressure is a pressure obtained by multiplying the first pressure by a predetermined ratio greater than 1.

8. The battery pack includes battery cells, and the battery cells include a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators that are alternately stacked, and a bag-shaped member that encloses the plurality of positive electrodes, the plurality of negative electrodes, and the plurality of separators. The bag-shaped member has a size such that after the restraint member is damaged and the restraint of the battery pack is released due to the pressure applied to the battery pack by the restraint member exceeding the predetermined pressure due to the change in thickness of the battery pack during charging and discharging, the stacking of the plurality of positive electrodes, the plurality of negative electrodes, and the plurality of separators is released and they can be separated from each other. The battery system according to any one of claims 1 to 7.

9. The battery pack has a plurality of units juxtaposed in the thickness direction, each of the plurality of units includes a plurality of battery cells, the battery system includes a BMS (Battery Management System) unit and an FPC (Flexible Printed Circuits) connected to the BMS unit, each of the plurality of units is connected to the FPC, and the FPC has a configuration of breaking by the force applied between the plurality of units when the restraint of the battery pack by the restraint member is released due to the pressure applied to the battery pack by the restraint member exceeding the predetermined pressure due to the change in thickness of the battery pack during charging and discharging. The battery system according to any one of claims 1 to 8.

10. The FPC includes current lines and voltage lines that electrically connect the BMS unit and the battery pack, and a film portion that covers the current lines and the voltage lines. The film portion has a breaking portion that breaks by the pressure applied between the plurality of units when the restraint of the battery pack by the restraint member is released. The battery system according to claim 9.

11. An aircraft comprising the battery system according to any one of claims 1 to 10 and a propulsion force generating device that generates a propulsion force using the electrical energy stored in the battery system.

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