Battery system and flight body

Abstract

SOLUTION: A battery system is provided, including a battery pack whose thickness is changed by charging and discharging, and a restraining member for restraining the battery pack and being the restraining member having a configuration to be broken down to release restraint of the battery pack in the case that the restraining member makes pressure applied to the battery pack exceed predetermined pressure due to a change in thickness by charging and discharging the battery pack. The restraining member may restrain the battery pack through two plate-like members sandwiching the battery pack along a thickness direction.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Patent Document 1 describes that in a lithium-ion battery, a plurality of stacked battery cells are sandwiched between metal plates, and the metal plates are restrained using a metal band, thereby applying a restraining pressure in the stacking direction to the battery cells. [Prior Art Document] [Patent Document] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2022-075152

Summary of the Invention

Means for Solving the Problems

[0003] According to one embodiment of the present invention, a battery system is provided. The battery system may include a battery pack whose thickness changes during charge and discharge. 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 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 during charge and discharge.

[0004] In the battery system, the restraining member may restrain the battery pack via two plate-like members that sandwich the battery pack along the thickness direction.

[0005] In any of the battery systems, the restraining member may be annular. The restraining member may break when the pressure applied to the battery pack by the restraining member exceeds the predetermined pressure. The battery pack may be a lithium metal battery. 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 to each other. The restraining member may have a configuration in which the fixing by the fixing portion is released when the pressure applied to the battery pack by the restraining member exceeds the predetermined pressure.

[0007] In any of the battery systems described above, the battery pack may have a characteristic in which 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. 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 battery cells. The battery cells may include a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators laminated alternately. The battery cells may include a bag-shaped member that encloses the plurality of positive electrodes, the plurality of negative electrodes, and the plurality of separators. After the restraining member is damaged and the restraint of the battery pack is released because the pressure applied to the battery pack by the restraining member exceeds the predetermined pressure due to the change in thickness of the battery pack during charge and discharge, the bag-shaped member may have a size such that the lamination 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.

[0009] In any of the above battery systems, the battery pack may have a plurality of units juxtaposed in the thickness direction. Each of the plurality of units may include a plurality of the battery cells. The battery system may include a BMS (battery management system) unit. The battery system may include an FPC (Flexible Printed Circuits) connected to the BMS unit. Each of the plurality of units may be connected to the FPC. The FPC may be configured to break by the force applied between the plurality of units when the pressure applied to the battery pack by the restraining member exceeds the predetermined pressure and the restraint of the battery pack by the restraining member is released due to the change in thickness caused by charging and discharging of the battery pack.

[0010] In any of the above battery systems, the FPC may include current lines and voltage lines that electrically connect the BMS unit and the battery pack. The FPC may include a film portion that covers the current lines and the voltage lines. The film portion may have a breaking portion that breaks by the force applied between the plurality of units when the restraint of the battery pack by the restraining member is released.

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

[0012] Note that the above summary of the invention does not list all the necessary features of the present invention. Also, sub-combinations of these feature groups can also be inventions.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0014] Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims. Also, not all combinations of features described in the embodiments are essential for the solution means of the invention.

[0015] In an existing battery pack, as a constituent member of the case that houses the battery pack, a material having firmness such as aluminum and CERP (Carbon Fiber Reinforced Plastics) material is generally used. However, when such a case is used, there are problems in ensuring the functionality and safety of the battery pack. Even if the thickness and internal pressure of the battery pack increase excessively due to the expansion of the internal cells caused by charge and discharge, since a firm material is used as the case, it is difficult to stop the operation of the battery by controlling the pressure. Also, in order to avoid the risk of failures and accidents such as abnormal high temperature and ignition, a mechanism is required to judge the deterioration of the cells at an early stage, cut off the internal current, and stop the function of the battery pack. The battery system 10 according to the present embodiment has, for example, a mechanism that semi-automatically releases the restraint of the cells, changes the pack structure, and cuts off the current when a specific pressure occurs inside the battery pack.

[0016] FIG. 1 schematically shows an example of the battery system 10. The battery system 10 includes a battery pack 100 and a restraint member 200.

[0017] The battery pack 100 packs batteries. The battery pack 100 according to the present embodiment has a characteristic that its thickness changes during charge and discharge, and its performance improves as the applied pressure increases up to a specific pressure, while the performance deteriorates when a pressure stronger than the specific pressure is applied. The battery pack 100 includes one or more batteries.

[0018] In the example shown in FIG. 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 one unit 110 instead of having a plurality of units 110. Each of the plurality of units 110 may include one battery cell 120 instead of including a plurality of battery cells 120.

[0019] The battery pack 100 may be any type of battery as long as it has a characteristic that its thickness changes during charge and discharge, and its performance improves as the applied pressure increases up to a specific pressure, while the performance deteriorates when a pressure stronger than the specific 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-like members 140 that sandwich the battery pack 100 along the thickness direction. The restraining member 200 may directly restrain the battery pack 100 without passing through the plate-like member 140.

[0021] FIG. 1 shows an example in which the battery system 10 includes three restraining members 200, and each restraining member 200 is arranged at an interval, but the number and arrangement of the restraining members 200 are not limited thereto. 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 a plurality of restraining members 200, the arrangement intervals of the plurality of restraining members 200 may be equal. The arrangement intervals of the plurality of restraining members 200 may not be equal. The plurality of restraining members 200 may be arranged without an interval.

[0022] When the battery pack 100 repeatedly charges and discharges, the thickness of the battery pack 100 gradually increases. Therefore, when the battery pack 100 repeatedly charges and discharges while being constrained by the constraint member 200, the internal pressure of the battery pack 100 increases. The constraint member 200 is configured to break when the pressure applied to the battery pack 100 due to the change in thickness during charging and discharging of the battery pack 100 exceeds a predetermined pressure, thereby releasing the constraint on the battery pack 100. Thereby, it is possible to prevent the internal pressure of the battery pack from becoming excessive. Consequently, it is possible to prevent a short circuit of the battery pack 100 and the accompanying ignition or the like in advance.

[0023] By the constraint member 200 constraining the battery pack 100 via the two plate-like members 140, the force with which the constraint member 200 constrains the battery pack 100 can be applied to the battery pack 100 more uniformly. Therefore, compared with the case where there is no plate-like member 140, local deformation of the battery pack 100 and the accompanying failure and performance degradation of the battery pack 100 can be suppressed. When there is no plate-like member 140, the possibility of local deformation of the battery pack 100 and the accompanying failure and performance degradation of the battery pack 100 is increased compared with the case where there is a plate-like member 140. However, depending on the configuration of the battery pack 100 and the like, such a possibility may not increase so much, and there is an advantage that the overall weight of the battery pack 100 can be reduced.

[0024] The plate-like 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 material with relatively high rigidity. The plate-like member 140 may be, for example, metal, and the metal may be, for example, iron or aluminum. As another example, the plate-like member 140 may be reinforced plastic, and the reinforced plastic may be, for example, FRP (Fiber Reinforced Plastics). Thereby, while ensuring the strength and rigidity of the plate-like member 140, the total weight of the battery system 10 can be suppressed, so that the weight energy density of the battery system 10 can be improved.

[0025] An interference 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 side of the plate-shaped member 140 that contacts 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 value and current value of the battery pack 100, and stops the charging and discharging of the battery pack 100 when an abnormality is detected. The BMS unit 150 may monitor the voltage value and current value during charging and discharging for each one or more units of the battery pack 100, and determine the presence or absence of an abnormality based on the voltage value and / or current value of each unit. The BMS unit 150 may determine the presence or absence of an abnormality based on the amount of change per unit time of the voltage value of each unit 110 and / or the amount of change per unit time of the current value of each unit. When the BMS unit 150 determines that an abnormality exists in each unit, it may stop the charging and discharging of the entire battery system 10. When the BMS unit 150 determines that an abnormality exists in each unit, it may stop the charging and discharging for each unit 110 of 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 the voltage line and the current line. When the battery pack 100 has a plurality of 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 shows an example of the restraining member 200. The restraining member 200 may have any configuration as long as it is configured to break 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 breaks 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 breaks when the pressure applied to the battery pack 100 by the restraining member 200 exceeds a predetermined pressure. The material of the restraining member 200 may be, for example, an organic fiber. The organic fiber may be, for example, a polyester fiber, a nylon fiber, a rayon fiber, a polyketone fiber, a polyamide fiber, or the like. By using an organic fiber as the material of the restraining member 200, the total weight of the battery system 10 can be suppressed while ensuring the strength and rigidity of the restraining member 200 as compared with the case of using a metal, so that the weight energy density of the battery system 10 can be improved. The polyamide fiber may be, for example, an aramid fiber. By using an aramid fiber as the material of the restraining member 200, the total weight of the battery system 10 can be suppressed while ensuring higher strength and rigidity of the restraining member 200 as compared with the cases of using a metal and other organic fibers, so that the weight energy density of the battery system 10 can be further improved.

[0029] The breaking strength of the restraining member 200 can be adjusted so that the restraining member 200 breaks when the pressure applied to the battery pack 100 exceeds a predetermined pressure. For example, the force received by the restraining member 200 from the battery pack 100 is calculated from the predetermined pressure and the area of the surface where the restraining member 200 contacts the battery pack 100, and based on this force, the number of restraining members 200 attached to the battery pack 100 and the breaking strength per restraining member 200 are adjusted.

[0030] The breaking strength per restraint member 200 can be adjusted by increasing or decreasing the cross-sectional area of the cross-section intersecting the circumferential direction of the restraint member 200 and / or by increasing or decreasing the breaking strength (breaking stress) per cross-section intersecting the circumferential direction of the restraint member 200. In this embodiment, the case where the material of the restraint member 200 is an organic fiber will be mainly described. For example, the cross-sectional area of the cross-section intersecting the circumferential direction of the restraint member 200 can be adjusted by increasing or decreasing the number of winding turns of the organic fiber. 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 the type and composition of the organic fiber selected and by post-treatments such as bending process and aging on the organic fiber.

[0031] FIG. 3 schematically shows another example of the restraint member 200. In the example shown in FIG. 3, different from the example shown in FIG. 2, the restraint member 200 has a belt portion 210 wound around the battery pack 100 and a fixing portion 220 that fixes different positions of the belt portion 210 to each other. When the pressure applied to the battery pack 100 by the restraint member 200 exceeds a predetermined pressure, the fixing by the fixing portion is released. 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 restraint member 200 exceeds a predetermined pressure. For example, the structure and shape of the fixing portion 220 may be a structure and shape imitating the structure and shape of a general 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-metal and may be a relatively high-strength plastic, such as FRP or the like.

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

[0033] For example, when the pressure applied to the battery pack 100 by the restraining member 200 exceeds a predetermined pressure, the fixing portion 220 may be released from the fixing by being damaged inside, but it is not limited thereto. As another example, the restraining member 200 may be released from the fixing by the fixing portion 220 when any of the connection portions 230 between the belt portion 210 and the fixing portion 220 is damaged. By configuring the restraining member 200 from the belt portion 210 and the fixing portion 220, the work of attaching the restraining member 200 to the battery pack 100 becomes simple, the breaking strength of the restraining member 200 can be easily adjusted, and an improvement in the accuracy of the adjustment of the breaking strength can be expected.

[0034] In the example shown in FIG. 3, for example, the fixing portion 220 may be damaged at the connecting portion 222. The connecting portion 222 may be formed of a different material having a lower strength than other portions of the fixing portion 220, for example. As another example, the connecting portion 222 may be formed of the same material as other portions of the fixing portion 220, and the cross-sectional area of the cross-section intersecting the circumferential direction of the fixing portion 220 may be formed smaller than other portions of the fixing portion 220. By adopting a configuration in which the fixing portion 220 has the connecting portion 222, the breaking strength of the restraining member 200 can be easily adjusted, and an improvement in the accuracy of the adjustment of the breaking strength can be expected.

[0035] FIG. 4 schematically shows 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 indicates the battery performance of the battery pack 100, and the horizontal axis indicates the restraint pressure of the battery pack 100. The battery performance may be an index obtained by analyzing the results obtained by conducting 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 conducting a cycle test on the battery pack 100, while repeating the charge and discharge of the battery pack 100 under specific conditions, the voltage value and current value of the battery pack 100 are measured, and the capacity retention rate, Coulomb efficiency, etc. of the battery pack 100 are calculated from the obtained voltage value and current value. As the charge and discharge are repeated, indexes such as the capacity retention rate and Coulomb efficiency of the battery pack 100 gradually decrease. The number of charge and discharge cycles at which any one or a plurality of indexes among the indexes such as the capacity retention rate and Coulomb efficiency fall below a preset threshold value may be defined as the cycle life [number of cycles] of the battery.

[0036] For example, by changing the condition of the pressure that restrains the battery pack 100 and conducting a cycle test on the battery, the relationship between the battery performance and the pressure as shown in FIG. 4 can be obtained. In the example shown in FIG. 4, until the applied pressure reaches the peak pressure P1, the greater the applied pressure, the better the battery performance. When a pressure greater than the peak pressure P1 is applied, the battery performance deteriorates. The pressure at which the restraint member 200 breaks may be a pressure determined based on the peak pressure P1. Thereby, until the battery performance of the battery pack 100 falls below a predetermined standard as the restraint pressure increases, while effectively using the battery pack 100, the restraint of the battery pack 100 can be released before falling below the predetermined standard, and it is possible to prevent a short circuit of the battery pack 100 and the accompanying ignition, etc. For example, the pressure at which the restraint member 200 breaks is the upper limit pressure P which is the pressure obtained by multiplying the peak pressure P1 by a ratio R1 greater than 1. ULThis may be the case. As a result, even after the battery performance of the battery pack 100 drops below the peak as the restraint pressure increases, the battery pack 100 can be effectively utilized under practical pressure conditions where the battery pack 100 can be effectively utilized, while preventing a short circuit of the battery pack 100 and ignition or the like associated therewith. The pressure at which the restraint member 200 breaks may be the peak pressure P1.

[0037] The peak pressure P1 may be an example of the first pressure. The upper limit pressure P UL may be an example of a predetermined pressure at which the restraint member 200 breaks. The ratio R1 may be an example of a predetermined ratio. The ratio R1 may be any ratio greater than 1. The ratio R1 may be 1.1, 1.2, 1.3, 1.4, 1.5, etc.

[0038] The test for obtaining the relationship between battery performance and pressure can be performed, for example, using a device that can press the battery pack 100 with a variable load along the thickness direction of the battery pack 100 and measure the load during pressing by means such as a load cell. By dividing the measured load by the area where the battery pack and the flat plate are in contact, the pressure applied to the battery pack 100, that is, the restraint pressure of the battery pack 100 can be obtained. By performing the above-described cycle test using such a device, the relationship between battery performance and pressure as shown in FIG. 4 can be obtained. The first pressure and a predetermined ratio greater than 1 may be influenced by various factors such as the type, structure, size, environmental conditions, and operating conditions of the battery pack. Therefore, it is desirable to specify for each target battery pack, environmental conditions, and operating conditions by the above-described tests and / or various simulation techniques.

[0039] FIG. 5 schematically shows an example of the battery cell 120. In FIG. 5, the structure of the battery cell 120 in a state where the battery pack 100 is constrained by the constraining member 200 will be described. The battery cell 120 includes a plurality of positive electrodes 122, a plurality of negative electrodes 124, and a plurality of separators 126 that are alternately stacked. The battery cell 120 includes a bag-shaped member 128 that encloses 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 contains an electrolyte.

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

[0041] FIG. 6 schematically shows an example of the battery cell 120. In the example shown in FIG. 6, after the constraining member 200 is damaged and the constraint of the battery pack 100 is released due to the pressure applied to the battery pack 100 by the constraining member 200 exceeding a predetermined pressure due to the change in thickness during charging and discharging of the battery pack 100, the state of the battery cell 120 will be described. Each configuration of the battery cell 120 is common to the example shown in FIG. 5. The description will be omitted.

[0042] Once the restraining member 200 is damaged and the restraint of the battery pack 100 is released, it is conceivable that the lamination of the plurality of positive electrodes 122, the plurality of negative electrodes 124, and the plurality of separators 126 will be easily released due to the generation of gas 136 or the like accompanying subsequent charge and discharge. In this case, the contact between the electrode and the electrolyte is inhibited, making it difficult to secure an ion conduction path and easily stopping the charge and discharge of the battery cell 120. In the example shown in FIG. 6, the bag-shaped member 128 has a size that allows the lamination of the plurality of positive electrodes 122, the plurality of negative electrodes 124, and the plurality of separators 126 to be released and separated from each other. Thereby, after the restraining member 200 is damaged and the restraint of the battery pack 100 is released, the lamination of the plurality of positive electrodes 122, the plurality of negative electrodes 124, and the plurality of separators 126 is easily released, and the charge and discharge of the battery cell 120 can be more reliably stopped.

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

[0044] FIG. 7 schematically shows an example of the battery system 10. In the example shown in FIG. 7, the battery pack 100 has a plurality of units 110 juxtaposed in the thickness direction, and each of the plurality of units 110 includes a plurality of 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 plurality of units 110 is connected to the FPC 160. The FPC 160 is configured to break by the force applied between the plurality of units 110 when the pressure applied to the battery pack 100 by the restraining member 200 exceeds a predetermined pressure and the restraint of the battery pack 100 by the restraining member 200 is released due to the change in thickness caused by the charge and discharge of the battery pack 100. Thereby, after the restraining member 200 is damaged and the restraint of the battery pack 100 is released, the charge and discharge of the battery cell 120 can be more reliably stopped.

[0045] In the battery system 10, a plurality of adjacent units 110 are in contact with each other, and a force of mutual pushing acts between them. The sum of this force and the force by which the restraining member 200 restrains the battery pack 100 is in balance. When the restraint of the battery pack 100 by the restraining member 200 is released, the force by which a plurality of adjacent units 110 are in contact with each other and push against each other is released. Due to this force, the thickness, shape, material, etc. of the FPC 160 are appropriately adjusted so that the FPC 160 breaks. Thereby, after the restraining member 200 is damaged and the restraint of the battery pack 100 is released, the charging and discharging of the battery cell 120 can be stopped more reliably.

[0046] When the restraining member 200 is damaged and the restraint of the battery pack 100 is released, due to the generation of gas or the like accompanying subsequent charging and discharging, the thickness of the unit 110 increases. Thereby, a force by which a plurality of adjacent units 110 are in contact with each other and push against each other acts. Due to this force, the thickness, shape, material, etc. of the FPC 160 may be appropriately adjusted so that the FPC 160 breaks. Thereby, after the restraining member 200 is damaged and the restraint of the battery pack 100 is released, the charging and discharging of the battery cell 120 can be stopped more reliably.

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

[0048] The FPC 160 may include current lines and voltage lines that electrically connect the BMS unit 150 and the battery pack 100, and a film portion that covers the current lines and voltage lines. The film portion may have a breaking portion 162 that breaks due to the force applied between the plurality of units 110 when the restraint of the battery pack 100 by the restraint member 200 is released. The position and shape of the breaking portion 162 on the FPC 160 may be at any position and in any shape on the FPC 160 as long as the breaking portion 162 is configured such that the FPC 160 breaks due to the force applied between the plurality of units 110 when the restraint of the battery pack 100 by the restraint member 200 is released. As an example, as shown in the example of FIG. 7, the position of the breaking portion 162 on the FPC 160 may be a position near the base of each unit of the FPC 160, a position connecting each unit of the FPC 160, and / or a position near the base of the BMS unit 150 of the FPC 160, but is not limited thereto. As an example, as shown in the example of FIG. 7, the shape of the breaking 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 breaking portion 162 is not limited to the notch shape. As another example, for example, the breaking portion 162 may be a perforated shape. Only the breaking portion 162 may be made of a different material. Thereby, among the FPC 160, the function of the portion that breaks when a predetermined force is applied and the portion that does not break are separated, and while ensuring the durability and electrical conductivity functions of the FPC 160, after the restraint member 200 is damaged and the restraint of the battery pack 100 is released, the charging and discharging of the battery cell 120 can be stopped more reliably.

[0049] The plurality of units 110 of the battery pack 100 may be connected to the BMS unit 150 in parallel with each other by the FPC 160. In the example shown in FIG. 7, for example, among the plurality of break portions 162, the FPC breaks at the break portion 162 near the base of one of the plurality of units 110. In this case, the current line of the one unit 110 may be cut, and the charge and discharge of the one unit may stop. The BMS unit 150 may stop the charge and discharge of the other units 110 other than the one unit based on the change in the current value of the one unit 110. Thereby, it is possible to more surely prevent a short circuit of the battery pack 100 and ignition accompanying therewith in advance. The BMS unit 150 may stop the charge and discharge of only the one unit 110 while continuing the charge and discharge of the other units 110 other than the one unit 110. Thereby, while maintaining the charge and discharge capabilities of the other units 110 in which no abnormality has been confirmed in the battery system 10 in an available state and minimizing the influence on the remaining power amount, only the unit 110 in which an abnormality has been confirmed is stopped, and a short circuit of the unit 110 and ignition accompanying therewith can be more surely prevented in advance.

[0050] In a similar case, when the voltage line of the one unit 110 is cut, the BMS unit 150 may stop the charge and discharge of the one unit based on the change in the voltage value of the one unit 110 and stop the charge and discharge of the other units 110 other than the one unit. Thereby, it is possible to more surely prevent a short circuit of the battery pack 100 and ignition accompanying therewith in advance. The BMS unit 150 may stop the charge and discharge of only the one unit 110 while continuing the charge and discharge of the other units 110 other than the one unit 110. Thereby, while maintaining the charge and discharge capabilities of the other units 110 in which no abnormality has been confirmed in the battery system 10 in an available state and minimizing the influence on the remaining power amount, only the unit 110 in which an abnormality has been confirmed is stopped, and a short circuit of the unit 110 and ignition accompanying therewith can be more surely prevented in advance.

[0051] All of the plurality of 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 any of a plurality of break portions 162. In this case, the current lines near the break portion 162 are cut, and all charge and discharge of the plurality of units 110 in the same battery system 10 stop. As a result, the battery system 10 stops without intervening the BMS unit 150. Therefore, even when a problem occurs in the abnormality detection function or the like of the BMS unit 150, it is possible to more surely prevent a short circuit of the battery system 10 and ignition associated therewith in advance without relying on electronic control by these functions.

[0052] In a similar case, when the voltage lines near the break portion 162 are cut, the BMS unit 150 may stop all charge and discharge of the plurality of units 110 in the same battery system 10 based on a change in the voltage value of the battery pack 100. The charge and discharge of the other units 110 other than the one unit 110 may be stopped. As a result, it is possible to more surely prevent a short circuit of the battery pack 100 and ignition associated therewith in advance.

[0053] FIG. 8 schematically shows an example of the HAPS 700 equipped with the battery system 10. The HAPS 700 is an aircraft that provides a wireless communication service to the user terminal 30 in the communication area 704 formed by irradiating the beam 702 toward the ground. The HAPS 700 may be an example of an aircraft including the battery system 10 and a propulsion force generating device that generates a propulsion force using the electrical energy stored in the battery system 10.

[0054] The HAPS 700 includes a fuselage 710, a central portion 720, a propeller 730, a pod 740, and a solar panel 750. The fuselage 710 has wing portions 712. The wing portions 712 include a left wing portion 714 and a right wing portion 716.

[0055] For example, the battery system 10 is arranged inside the wing portion 712. The electrical energy stored in the battery system 10 is utilized by each component provided in the HAPS 700. For example, the electrical energy stored in the battery system 10 is utilized by the motor of the propeller 730 that generates thrust. As a specific example, a plurality of battery systems 10 connected in parallel are arranged inside the wing portion 712. Among the plurality of battery systems 10, the plurality of battery systems 10 on the left side may be arranged in the left wing portion 714, and the plurality of battery systems 10 on the right side may be arranged in the right wing portion 716. The electric power discharged by the plurality of battery systems 10 is utilized by each component provided in 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] Inside the central portion 720, a flight control unit 722 and a communication control unit 724 are arranged. The flight control unit 722 controls the flight of the HAPS 700 using the electric power discharged by the plurality of battery systems 10. The communication control unit 724 controls the communication of the HAPS 700 using the electric power discharged by the plurality of 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. Also, the flight control unit 722 may control the flight of the HAPS 700 by changing the angles of flaps and elevators (not shown). The flight control unit 722 may be provided with various sensors such as a positioning sensor such as a GPS sensor, a gyro sensor, and an acceleration sensor to manage the position, moving direction, and moving speed of the HAPS 700.

[0058] The communication control unit 724 forms a communication area 704 on the ground using an SL (Service Link) antenna. The communication control unit 724 forms a service link with the ground 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 form a feeder link with the ground gateway 40 using a FL (Feeder Link) antenna. The communication control unit 724 may access the network 20 via the gateway 40.

[0060] The communication control unit 724 may communicate with the communication satellite 50 using a satellite communication antenna. 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 as long as it can communicate with the HAPS 700. For example, the user terminal 30 is a mobile phone such as a smartphone. The user terminal 30 may be a tablet terminal, a PC (Personal Computer), etc. The user terminal 30 may be a so-called IoT (Internet of Thing) device. The user terminal 30 may include anything corresponding to the so-called IoE (Internet of Everything).

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

[0063] The network 20 includes a mobile communication network. The mobile communication network may comply with any of the communication methods such as the LTE (Long Term Evolution) communication method, the 5G (5th Generation) communication method, the 3G (3rd Generation) communication method, and the communication methods after the 6G (6th Generation) communication method. The network 20 may include the Internet.

[0064] HAPS700 transmits data received from, for example, user terminal 30 within communication area 704 to network 20. Further, HAPS700 transmits the data to user terminal 30 when it receives data destined for user terminal 30 within communication area 704 via network 20, for example.

[0065] HAPS700 maintains communication area 704 over a specific area on the ground while orbiting a predetermined flight path in the stratosphere, for example. HAPS700 stores the power generated by solar cell panel 750 during the day in a plurality of battery systems 10 and maintains flight in the stratosphere by using the power of the plurality of battery systems 10 at night. HAPS700, for example, ascends while charging the plurality of battery systems 10 during the day to store potential energy, and at night, descends gently while appropriately using the power of battery system 10 to operate propeller 730 or the like to maintain flight in the stratosphere.

[0066] Management device 800 manages a plurality of HAPS700. Management device 800 may communicate with HAPS700 via network 20 and gateway 40. Management device 800 may also communicate with HAPS700 via network 20, satellite communication station 60, and communication satellite 50.

[0067] Management device 800 controls HAPS700 by transmitting an instruction. Management device 800 may cause HAPS700 to circle over the target area so that communication area 704 covers the target area on the ground. HAPS700, for example, maintains a feeder link with gateway 40 by adjusting the pointing direction of the FL antenna while flying in a circular orbit over the target area, and maintains coverage of the target area by communication area 704 by adjusting the pointing direction of the SL antenna.

[0068] As described above, the present invention has been explained using embodiments. However, the technical scope of the present invention is not limited to the scope described in the above embodiments. It is obvious to those skilled in the art that various changes or improvements can be made to the above embodiments. It is clear from the description of the claims that forms with such changes or improvements can also be included in the technical scope of the present invention.

[0069] Regarding the execution order of each process such as operations, procedures, steps, and stages in the apparatuses, systems, programs, and methods shown in the claims, the specification, and the drawings, unless it is explicitly stated such as "earlier" or "preceding", and unless the output of the previous process is used in the subsequent process, it should be noted that it can be realized in any order. Regarding the operation flows in the claims, the specification, and the drawings, even if explanations are made using "first," "next," etc. for convenience, it does not mean that it is essential to implement in this order.

Explanation of Reference Numerals

[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 unit, 160 FPC, 162 Fracture part, 200 Restraining member, 210 Band part, 220 Fixed part, 222 Connecting part, 230 Connection part, 700 HAPS, 702 Beam, 704 Communication area, 710 Aircraft body, 712 Wing part, 714 Left wing part, 716 Right wing part, 720 Central part, 722 Flight control part, 724 Communication control part, 730 Propeller, 740 Pod, 750 Solar panel, 800 Management device

Claims

1. a battery pack whose thickness changes upon charge and discharge, and a restraining member for restraining the battery pack, the restraining member having a configuration in which 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 charge and discharge, the restraining member breaks and the restraint of the battery pack is released A battery system comprising:

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

5. The battery system according to claim 1, 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 has a configuration in which when the pressure applied to the battery pack by the restraining member exceeds the predetermined pressure, the fixing by the fixing portion is released.

6. 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. The battery system according to any one of claims 1 to 4, wherein 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, The battery cells include a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators that are alternately laminated, and a bag-like member that encloses the plurality of positive electrodes, the plurality of negative electrodes, and the plurality of separators and include. The battery system according to any one of claims 1 to 4, wherein 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 caused by charging and discharging of the battery pack, the lamination 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.

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 and is provided with, each of the plurality of units is connected to the FPC, The battery system according to any one of claims 1 to 4, wherein the FPC has a configuration such that when the pressure applied to the battery pack by the restraint member exceeds the predetermined pressure due to the change in thickness caused by charging and discharging of the battery pack and the restraint of the battery pack by the restraint member is released, the FPC breaks due to the force applied between the plurality of units.

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 and is included, the film portion has a breaking portion that breaks due to 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. A flying object comprising: the battery system according to any one of claims 1 to 4, and a propulsion force generating device that generates a propulsion force using the electrical energy stored in the battery system.

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