Restraint tool, battery system, and flying body

Abstract

Provided is a restraint tool for restraining a lithium metal battery including a plurality of battery cells, said restraint tool comprising: a restraint member including a plate-shaped member that is made of rubber and includes a plate-shaped base part and a plurality of projections on the base part, and the restraint member including a frame member into which the plate-shaped member is fitted; and a fixing member for pressing the plate-shaped member, which is fitted to the frame member, against the lithium metal battery to fix the plate-shaped member to the lithium metal battery in a pressurized state. In accordance with the elasticity of the plate-shaped member, the restraint tool applies a pressure of 5 MPa or less to the plurality of battery cells during charging of the plurality of battery cells, and applies a pressure of 0.1 MPa or greater to the plurality of battery cells during discharging of the plurality of battery cells.

Description

Restraint, battery system, and flying vehicle

[0001] The present invention relates to a restraint device, 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] According to one embodiment of the present invention, there is provided a restraint. The restraint may restrain a lithium metal battery including a plurality of battery cells. The restraint may include a restraining member. The restraint member may be made of a rubber-based material and include a plate-shaped member having a plate-shaped base and a plurality of protrusions on the base, and a frame member into which the plate-shaped member is fitted. The restraint may include a fixing member that presses the plate-shaped member fitted into the frame member against the lithium metal battery and fixes it in a pressurized state.

[0004] In the restraint device, each of the plurality of protrusions may have a conical shape. Each of the plurality of protrusions may have a conical shape with a height-to-diameter ratio between 1:1 and 1:5. Each of the plurality of protrusions may have a conical shape with a height-to-diameter ratio of 1:3. The apex sides of the plurality of protrusions may be curved. The apex sides of the plurality of protrusions may be flat. The diameter of the base of the plurality of protrusions may be 5 mm to 30 mm.

[0005] In any of the above restraint devices, rectangular protrusions with a notch in the center along the vertical direction of the base and rectangular protrusions with a notch in the center along the horizontal direction of the base may be arranged alternately on the base.

[0006] In any of the restraining devices, the elasticity of the plate-shaped member may cause the pressure applied by the restraining device to be 5 MPa or less when the multiple battery cells are charged, and the pressure applied by the restraining device to be 0.1 MPa or more when the multiple battery cells are discharged. The restraining device is configured by adjusting the type of rubber that is the material of the plate-shaped member, the shape, number, and arrangement of the multiple protrusions of the plate-shaped member, and the fixing force of the fixing member so that the elasticity of the plate-shaped member causes the pressure applied by the restraining device to be 5 MPa or less when the multiple battery cells are charged, and the pressure applied by the restraining device to be 0.1 MPa or more when the multiple battery cells are discharged. The pressure applied by the restraining device to the multiple battery cells when the multiple battery cells are charged may be 3 MPa or less. The pressure applied by the restraining device to the multiple battery cells when the multiple battery cells are charged may be 2 MPa or less. The pressure applied to the battery cells by the restraining device during discharge of the battery cells may be 0.3 MPa or more. The pressure applied to the battery cells by the restraining device during discharge of the battery cells may be 0.5 MPa or more.

[0007] In any of the above restraint devices, the restraining member may include a first restraining member having a first plate-shaped member and a first frame member, and a second restraining member having a second plate-shaped member and a second frame member, and the fixing member may fix the lithium metal battery in a state where the lithium metal battery is sandwiched and pressurized between the first restraining member and the second restraining member. The gap between the plurality of protrusions may be 0.05 to 0.3 times the area of ​​the base. The gap between the plurality of protrusions may be 0.1 to 0.2 times the area of ​​the base. The material of the plate-shaped member may be ethylene propylene diene rubber.

[0008] According to one embodiment of the present invention, there is provided a battery system including the restraint device and the lithium metal battery. According to another 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.

[0009] 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.

[0010] 1 schematically illustrates an example of a battery system 10. 1 schematically illustrates an example of a battery system 10. 1 schematically illustrates an example of a plate-shaped member 212. 1 schematically illustrates an example of a frame member 218. 1 schematically illustrates an example of a plate-shaped member 212. 1 schematically illustrates an example of a plate-shaped member 212. 1 schematically illustrates an example of a HAPS 700 equipped with the battery system 10.

[0011] 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.

[0012] Lithium-ion batteries can achieve sufficient battery performance by restraining them with no or low pressure, approximately 0.0 to 0.2 MPa. On the other hand, it has been discovered that restraining lithium metal batteries with the same pressure as lithium-ion batteries results in poor cycle life. Increasing the restraining pressure using methods such as metal plate restraint improves cycle life, but the restraining member becomes heavier, resulting in a decrease in weight energy density. Furthermore, lithium metal batteries change in thickness with charge and discharge. However, metal plate restraints do not properly adjust the pressure, which can result in excessive or insufficient restraining pressure on the lithium metal battery. The restraining device 200 according to this embodiment is lighter in weight than metal plate restraints and has a structure that properly adjusts the restraining pressure on the lithium metal battery when the thickness of the lithium metal battery changes with charge and discharge.

[0013] 1 and 2 schematically show an example of a battery system 10. The battery system 10 includes a lithium metal battery 100 and a restraint device 200. The lithium metal battery 100 includes a plurality of battery cells 110. The plurality of battery cells 110 are arranged side by side.

[0014] The restraint device 200 restrains the lithium metal battery 100. The restraint device 200 may restrain the lithium metal battery 100 along the direction in which the plurality of battery cells 110 are arranged.

[0015] 1 and 2 , restraint device 200 has restraint member 210, restraint member 220, and fixing member 230. Restraint member 210 may be an example of a first restraint member. Restraint member 220 may be an example of a second restraint member. Fixing member 230 fixes lithium metal battery 100 in a state in which it is sandwiched and pressurized by restraint members 210 and 220.

[0016] Note that the restraining device 200 may include only one of the restraining member 210 and the restraining member 220. For example, the restraining device 200 includes only the restraining member 210 of the restraining member 210 and the restraining member 220. In this case, a member formed of a material with relatively high hardness and relatively light weight, such as carbon fiber composite material (CFRP: Carbon Fiber Reinforced Plastics), is disposed on the side of the lithium metal battery 100 opposite the side where the restraining member 210 is located. The fixing member 230 presses the restraining member 210 against the lithium metal battery 100 and fixes it in a pressurized state. The fixing member 230 may sandwich the lithium metal battery 100 between the restraining member 210 and a member disposed on the side of the lithium metal battery 100 opposite the side where the restraining member 210 is located, and fixes it in a pressurized state.

[0017] In this embodiment, a case where the restraint device 200 includes a restraint member 210 and a restraint member 220 will be mainly described as an example.

[0018] The restraining member 210 includes a plate-shaped member 212 and a frame member 218. The plate-shaped member 212 may be an example of a first plate-shaped member. The frame member 218 may be an example of a first frame member.

[0019] The plate-shaped member 212 is made of a rubber-based material. Specific examples of the material of the plate-shaped member 212 include, but are not limited to, ethylene propylene diene rubber (EPDM). Other examples include, but are not limited to, natural rubber, styrene butadiene rubber, nitrile rubber, butyl rubber, chloroprene rubber, chlorosulfonated polyethylene rubber, acrylic rubber, silicone rubber, and fluororubber.

[0020] The plate-shaped member 212 has a plate-shaped base 214 and a plurality of protrusions 216 on the base 214. The base 214 may be an example of a first base. The protrusions 216 may be an example of a first protrusion. The plurality of protrusions 216 may have a configuration that applies pressure to the lithium metal battery 100 as uniformly as possible and is less likely to buckle. The gap between the plurality of protrusions 216 may be 0.05 to 0.3 of the area of ​​the base 214. The gap between the plurality of protrusions 216 may be 0.1 to 0.2 of the area of ​​the base 214.

[0021] The plate-shaped member 212 is fitted into the frame member 218. The frame member 218 has a recess, into which the plate-shaped member 212 is fitted. The frame member 218 may be formed from a material that is relatively hard and relatively light in weight. An example of the material of the frame member 218 is CFRP, but is not limited to this.

[0022] The restraining member 220 includes a plate-shaped member 222 and a frame member 228. The restraining member 220 has a configuration similar to that of the restraining member 210. The plate-shaped member 222 may be an example of a second plate-shaped member. The frame member 228 may be an example of a second frame member.

[0023] The plate-shaped member 222 is made of a rubber-based material. Specific examples of the material of the plate-shaped member 222 include, but are not limited to, ethylene propylene diene rubber. Other examples include, but are not limited to, natural rubber, styrene butadiene rubber, nitrile rubber, butyl rubber, chloroprene rubber, chlorosulfonated polyethylene rubber, acrylic rubber, silicone rubber, and fluororubber.

[0024] Plate-shaped member 222 has a plate-shaped base 224 and a plurality of protrusions 226 on base 224. Base 224 may be an example of a second base. Protrusions 226 may be an example of a second protrusion. The plurality of protrusions 226 may have a configuration that applies pressure to lithium metal battery 100 as uniformly as possible and is less likely to buckle.

[0025] The plate-shaped member 222 is fitted into the frame member 228. The frame member 228 has a recess, into which the plate-shaped member 222 is fitted. The frame member 228 may be formed from a material that is relatively hard and relatively light in weight. An example of the material of the frame member 228 is CFRP, but is not limited to this.

[0026] Fixing member 230 may be any member that can fix lithium metal battery 100 in a state in which it is sandwiched and pressurized between restraining members 210 and 220. Fixing member 230 may be, for example, a box-shaped member made of a material that is relatively hard and relatively light, such as CFRP.

[0027] The restraining member 210, the restraining member 220, and the fixing member 230 are configured such that the elasticity of the plate-shaped member 212 of the restraining member 210 and the elasticity of the plate-shaped member 222 of the restraining member 220 cause the pressure exerted by the restraining device 200 on the plurality of battery cells 110 of the lithium metal battery 100 to be 5 MPa or less when the plurality of battery cells 110 are being charged, and the pressure exerted by the restraining device 200 on the plurality of battery cells 110 to be 0.1 MPa or more when the plurality of battery cells 110 are being discharged. In other words, the restraining member 210, the restraining member 220, and the fixing member 230 are configured such that the pressure exerted on the lithium metal battery 100 is 0.1 MPa to 5 MPa even if the thickness of the lithium metal battery 100 changes due to charging and discharging. Specifically, to achieve this pressure, the restraint device 200 is constructed by adjusting the type of rubber used for the plate-shaped member 212, the shape, number, and arrangement of the multiple protrusions 216 on the plate-shaped member 212, the type of rubber used for the plate-shaped member 222, the shape, number, and arrangement of the multiple protrusions 226 on the plate-shaped member 222, and the fixing force provided by the fixing member 230. For example, various variations of the restraint device 200 can be created by changing some or all of the following: the type of rubber used for the plate-shaped member 212; the shape, number, and arrangement of the multiple protrusions 216 on the plate-shaped member 212; the type of rubber used for the plate-shaped member 222; the shape, number, and arrangement of the multiple protrusions 226 on the plate-shaped member 222; and the fixing force of the fixing member 230. The lithium metal battery 100 can then be actually restrained with the created restraint device 200, and the pressure applied to the lithium metal battery 100 when the lithium metal battery 100 is charged and discharged can be measured using a load cell or the like. By adopting a restraint device 200 that applies a pressure of 0.1 MPa to 5 MPa to the lithium metal battery 100, the restraint device 200 according to this embodiment can be created.

[0028] Similarly, the restraining member 210, the restraining member 220, and the fixing member 230 may be configured such that the elasticity of the plate-shaped member 212 of the restraining member 210 and the elasticity of the plate-shaped member 222 of the restraining member 220 result in the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 of the lithium metal battery 100 are being charged being 3 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are being discharged being 0.1 MPa or more.

[0029] Similarly, the restraining member 210, the restraining member 220, and the fixing member 230 may be configured so that the elasticity of the plate-shaped member 212 of the restraining member 210 and the elasticity of the plate-shaped member 222 of the restraining member 220 cause the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 of the lithium metal battery 100 are being charged to be 2 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are being discharged to be 0.1 MPa or more.

[0030] Similarly, the restraining member 210, the restraining member 220, and the fixing member 230 may be configured so that the elasticity of the plate-shaped member 212 of the restraining member 210 and the elasticity of the plate-shaped member 222 of the restraining member 220 cause the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 of the lithium metal battery 100 are charged to be 5 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are discharged to be 0.3 MPa or more.

[0031] Similarly, the restraining member 210, the restraining member 220, and the fixing member 230 may be configured so that the elasticity of the plate-shaped member 212 of the restraining member 210 and the elasticity of the plate-shaped member 222 of the restraining member 220 cause the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 of the lithium metal battery 100 are charged to be 3 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are discharged to be 0.3 MPa or more.

[0032] Similarly, the restraining member 210, the restraining member 220, and the fixing member 230 may be configured so that the pressure exerted by the restraining device 200 on the multiple battery cells 110 of the lithium metal battery 100 when the multiple battery cells 110 are being charged is 2 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are being discharged is 0.3 MPa or more, due to the elasticity of the plate-shaped member 212 of the restraining member 210 and the elasticity of the plate-shaped member 222 of the restraining member 220.

[0033] Similarly, the restraining member 210, the restraining member 220, and the fixing member 230 may be configured such that the elasticity of the plate-shaped member 212 of the restraining member 210 and the elasticity of the plate-shaped member 222 of the restraining member 220 result in the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 of the lithium metal battery 100 are being charged being 5 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are being discharged being 0.5 MPa or more.

[0034] Similarly, the restraining member 210, the restraining member 220, and the fixing member 230 may be configured so that the elasticity of the plate-shaped member 212 of the restraining member 210 and the elasticity of the plate-shaped member 222 of the restraining member 220 cause the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 of the lithium metal battery 100 are being charged to be 3 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are being discharged to be 0.5 MPa or more.

[0035] Similarly, the restraining member 210, the restraining member 220, and the fixing member 230 may be configured so that the pressure exerted by the restraining device 200 on the multiple battery cells 110 of the lithium metal battery 100 when the multiple battery cells 110 are being charged is 2 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are being discharged is 0.5 MPa or more, due to the elasticity of the plate-shaped member 212 of the restraining member 210 and the elasticity of the plate-shaped member 222 of the restraining member 220.

[0036] When the restraining device 200 only includes the restraining member 210 out of the restraining member 210 and the restraining member 220, the restraining member 210 and the fixing member 230 may be configured so that, due to the elasticity of the plate-shaped member 212 of the restraining member 210, the pressure exerted by the restraining device 200 on the multiple battery cells 110 of the lithium metal battery 100 when the multiple battery cells 110 are charged is 5 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are discharged is 0.1 MPa or more. In other words, the restraining member 210 and the fixing member 230 are configured so that the pressure exerted on the lithium metal battery 100 is 0.1 MPa to 5 MPa even if the thickness of the lithium metal battery 100 changes due to charging and discharging. Specifically, the restraining device 200 is configured by adjusting the type of rubber used for the plate-shaped member 212, the shape, number, and arrangement of the multiple protrusions 216 of the plate-shaped member 212, and the fixing force of the fixing member 230 to achieve such pressure. For example, various variations of the restraint device 200 can be created by changing some or all of the rubber type of the plate-shaped member 212, the shape, number, and arrangement of the multiple protrusions 216 of the plate-shaped member 212, and the fixing force of the fixing member 230, and then actually restraining the lithium metal battery 100 with the created restraint device 200.The pressure applied to the lithium metal battery 100 when the lithium metal battery 100 is charged and discharged can be measured using a load cell or the like, and the restraint device 200 that applies a pressure of 0.1 MPa to 5 MPa to the lithium metal battery 100 can be used to create the restraint device 200 of this embodiment.

[0037] Similarly, the restraining member 210 and the fixing member 230 may be configured so that, due to the elasticity of the plate-shaped member 212 of the restraining member 210, the pressure exerted by the restraining device 200 on the multiple battery cells 110 of the lithium metal battery 100 when the multiple battery cells 110 are being charged is 3 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are being discharged is 0.1 MPa or more.

[0038] Similarly, the restraining member 210 and the fixing member 230 may be configured so that, due to the elasticity of the plate-shaped member 212 of the restraining member 210, the pressure exerted by the restraining device 200 on the multiple battery cells 110 of the lithium metal battery 100 when the multiple battery cells 110 are being charged is 2 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are being discharged is 0.1 MPa or more.

[0039] Similarly, the restraining member 210 and the fixing member 230 may be configured so that, due to the elasticity of the plate-shaped member 212 of the restraining member 210, the pressure exerted by the restraining device 200 on the multiple battery cells 110 of the lithium metal battery 100 when the multiple battery cells 110 are being charged is 5 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are being discharged is 0.3 MPa or more.

[0040] Similarly, the restraining member 210 and the fixing member 230 may be configured so that, due to the elasticity of the plate-shaped member 212 of the restraining member 210, the pressure exerted by the restraining device 200 on the multiple battery cells 110 of the lithium metal battery 100 when the multiple battery cells 110 are being charged is 3 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are being discharged is 0.3 MPa or more.

[0041] Similarly, the restraining member 210 and the fixing member 230 may be configured so that, due to the elasticity of the plate-shaped member 212 of the restraining member 210, the pressure exerted by the restraining device 200 on the multiple battery cells 110 of the lithium metal battery 100 when the multiple battery cells 110 are being charged is 2 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are being discharged is 0.3 MPa or more.

[0042] Similarly, the restraining member 210 and the fixing member 230 may be configured so that, due to the elasticity of the plate-shaped member 212 of the restraining member 210, the pressure exerted by the restraining device 200 on the multiple battery cells 110 of the lithium metal battery 100 when the multiple battery cells 110 are being charged is 5 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are being discharged is 0.5 MPa or more.

[0043] Similarly, the restraining member 210 and the fixing member 230 may be configured so that, due to the elasticity of the plate-shaped member 212 of the restraining member 210, the pressure exerted by the restraining device 200 on the multiple battery cells 110 of the lithium metal battery 100 when the multiple battery cells 110 are being charged is 3 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are being discharged is 0.5 MPa or more.

[0044] Similarly, the restraining member 210 and the fixing member 230 may be configured so that, due to the elasticity of the plate-shaped member 212 of the restraining member 210, the pressure exerted by the restraining device 200 on the multiple battery cells 110 of the lithium metal battery 100 when the multiple battery cells 110 are being charged is 2 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are being discharged is 0.5 MPa or more.

[0045] Table 1 below shows experimental results of testing the capacity retention rate of the battery cell 110 after 200 cycles for each pressure applied to the battery cell 110 during charging and discharging. Table 1 shows experimental results of testing the capacity retention rate of the battery cell 110 after 200 cycles for each combination of the pressure at the end of charging, at which the pressure applied to the battery cell 110 during charging is the strongest, and the pressure at the end of discharging, at which the pressure on the battery cell 110 during discharging is the weakest. The experiment was conducted multiple times for each combination of the pressure applied to the battery cell 110 during charging and the pressure applied to the battery cell 110 during discharging. Cases where the number of cycles was 200 or less were marked with "X", cases where the capacity retention rate at 200 cycles was less than 70% were marked with "Δ", cases where the capacity retention rate at 200 cycles was 70% or more but less than 90% were marked with "◯", and cases where the capacity retention rate at 200 cycles was 90% or more were marked with "◎".

[0046] The experimental results show that, for example, when the battery cell 110 was charged and discharged 200 times under conditions in which the pressure at the end of charging was 2 MPa and the pressure at the end of discharging was 0.3 MPa, the capacity retention rate of the battery cell 110 was 90% or more.

[0047] The experimental results show that by setting the pressure applied during charging to a maximum of 2 MPa or 3 MPa and the pressure applied during discharging to a minimum of 0.3 MPa, 0.5 MPa, or 0.6 MPa, the capacity retention rate of the lithium metal battery 100 is 90% or more when the battery cell 110 is charged and discharged 200 times.

[0048]

[0049] As shown in Table 1, the charge pressure is preferably 0.8 MPa to 6 MPa, more preferably 1 MPa to 5 MPa, more preferably 1 MPa to 4 MPa, and even more preferably 2 MPa or 3 MPa. The discharge pressure is preferably 0.1 MPa to 0.6 MPa, more preferably 0.2 MPa to 0.6 MPa, and even more preferably 0.3 MPa to 0.6 MPa.

[0050] As shown in Table 1, it is desirable that the charging pressure be 1 MPa to 4 MPa and the discharging pressure be 0.2 MPa to 0.6 MPa, and it is even more desirable that the charging pressure be 2 MPa or 3 MPa and the discharging pressure be 0.3 MPa to 0.6 MPa. The restraint device 200 according to this embodiment can restrain the lithium metal battery 100 so as to satisfy these range conditions, thereby contributing to maintaining the performance of the lithium metal battery 100.

[0051] Fig. 3 schematically shows an example of the plate-shaped member 212. The dimensions of the plate-shaped member 212 shown in Fig. 3 are one example. The dimensions of the plate-shaped member 212 can be determined according to the material of the plate-shaped member 212, etc., so that the pressure exerted by the restraining device 200 on the multiple battery cells 110 of the lithium metal battery 100 when the multiple battery cells 110 are charged is 5 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are discharged is 0.1 MPa or more. The plate-shaped member 222 may have the same configuration as the plate-shaped member 212.

[0052] In the example shown in Fig. 3, the base 214 is 93 mm long, 66 mm wide, and 4 mm high. The protrusion 216 has a rectangular shape. The protrusion 216 is 12 mm long, 12 mm wide, and 10 mm high. The multiple protrusions 216 are arranged side by side in the vertical and horizontal directions. The spacing between the multiple protrusions 216 is 2 mm.

[0053] This structure of the plate-like member 212 makes it difficult for the protrusions 216 to buckle, allowing uniform pressure to act on the battery cell 110, and also making it possible to appropriately adjust the pressure applied to the lithium metal battery 100 in the event of a change in the thickness of the lithium metal battery 100. Furthermore, the possibility of the lithium metal battery 100 becoming misaligned due to friction between the protrusions 216 and the lithium metal battery 100 can be reduced.

[0054] FIG. 4 schematically shows an example of the frame member 218. The dimensions shown in FIG. 4 are merely an example, and other dimensions may be used. The frame member 218 has a recess 219. The depth of the recess 219 may be the same as the height of the base 214. The depth of the recess 219 may be one-tenth to one-half the height of the base 214. The depth of the recess 219 may be one-fifth to one-third the height of the base 214. The frame member 228 may have the same configuration as the frame member 218.

[0055] Fig. 5 schematically illustrates an example of the plate-shaped member 212. The dimensions of the plate-shaped member 212 illustrated in Fig. 5 are merely an example. The dimensions of the plate-shaped member 212 can be determined according to the material of the plate-shaped member 212, etc., so that the pressure exerted by the restraining device 200 on the multiple battery cells 110 of the lithium metal battery 100 when the multiple battery cells 110 are being charged is 5 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are being discharged is 0.1 MPa or more. The plate-shaped member 222 may have the same configuration as the plate-shaped member 212.

[0056] In the example shown in Fig. 5, the base 214 is 93 mm long, 66 mm wide, and 4 mm high. In the example shown in Fig. 5, rectangular protrusions 2162 each having a notch in the center along the longitudinal direction of the base 214 and rectangular protrusions 2164 each having a notch in the center along the transverse direction of the base 214 are arranged alternately on the base 214. In the example shown in Fig. 5, the overall dimensions of the protrusions 2162 and 2164 are 12 mm long, 12 mm wide, and 10 mm high. The width of the notch is 6 mm, and the height of the notch is 8 mm. That is, the depth of the notch is 2 mm. The distance between the protrusions 2162 and 2164 is 2 mm.

[0057] As shown in Figure 5, by arranging the protrusions with cuts in different directions alternately, in addition to the advantages of the structure shown in Figure 3, the directionality of rubber deformation can be canceled, and the possibility of excessive pressure being applied to part of the battery cell 110 and damaging the battery cell 110 can be reduced.

[0058] Fig. 6 schematically shows an example of the plate-shaped member 212. The dimensions of the plate-shaped member 212 shown in Fig. 6 are one example. The dimensions of the plate-shaped member 212 can be determined according to the material of the plate-shaped member 212, etc., so that the pressure exerted by the restraining device 200 on the multiple battery cells 110 of the lithium metal battery 100 when the multiple battery cells 110 are charged is 5 MPa or less, and the pressure exerted by the restraining device 200 on the multiple battery cells 110 when the multiple battery cells 110 are discharged is 0.1 MPa or more. The plate-shaped member 222 may have the same configuration as the plate-shaped member 212.

[0059] In the example shown in FIG. 6 , the base 214 is 93 mm long, 66 mm wide, and 4 mm high. The protrusion 216 has a conical shape. The apex side of the protrusion 216 may be curved. The apex side of the protrusion 216 may be flat. The height-to-diameter ratio of the protrusion 216 may be between 1:1 and 1:5. The height-to-diameter ratio of the protrusion 216 may be 1:3. The diameter of the bottom of the protrusion 216 may be 5 mm to 30 mm. In the example shown in FIG. 6 , the diameter of the bottom of the protrusion 216 is 12 mm, and the height is 10 mm. The protrusion 216 may also be a quadrangular pyramid shape.

[0060] This structure of the plate-like member 212 makes it difficult for the protrusions 216 to buckle, allowing uniform pressure to act on the battery cell 110, and also making it possible to appropriately adjust the pressure applied to the lithium metal battery 100 in the event of a change in the thickness of the lithium metal battery 100. Furthermore, the possibility of the lithium metal battery 100 becoming misaligned due to friction between the protrusions 216 and the lithium metal battery 100 can be reduced.

[0061] 7 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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).

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 10 Battery system, 20 Network, 30 User terminal, 40 Gateway, 50 Communication satellite, 60 Satellite communication station, 100 Lithium metal battery, 110 Battery cell, 200 Restraint, 210 Restraint member, 212 Plate-shaped member, 214 Base, 216 Protrusion, 2162 Protrusion, 2164 Protrusion, 218 Frame member, 219 Grooving, 220 Restraint member, 222 Plate-shaped member, 224 Base, 226 Protrusion, 228 Frame member, 230 Fixing member, 700 HAPS, 702 Beam, 704 Communication area, 710 Airframe, 712 Wing section, 714 Left wing section, 716 Right wing section, 720 Center section, 722 Flight control section, 724 Communication control section, 730 Propeller, 740 Pod, 750 Solar panel, 800 Management device

Claims

1. A restraint device for restraining a lithium metal battery containing multiple battery cells, comprising: a plate-shaped member made of a rubber-based material and having a plate-shaped base and multiple protrusions on the base; and a frame member into which the plate-shaped member is fitted; and a fixing member that presses the plate-shaped member fitted into the frame member against the lithium metal battery and fixes it in place under pressure.

2. The restraint device of claim 1, wherein each of said plurality of protrusions has a conical shape.

3. The restraint of claim 2, wherein each of said plurality of protrusions has a conical shape with a height to diameter ratio between 1:1 and 1:

5.

4. A restraint device as described in claim 1, wherein rectangular protrusions having a central cut running along the vertical direction of the base and rectangular protrusions having a central cut running along the horizontal direction of the base are arranged alternately on the base.

5. A restraint device as described in any one of claims 1 to 4, wherein due to the elasticity of the plate-shaped member, the pressure exerted by the restraint device on the multiple battery cells when the multiple battery cells are being charged is 5 MPa or less, and the pressure exerted by the restraint device on the multiple battery cells when the multiple battery cells are being discharged is 0.1 MPa or more.

6. The restraint device according to claim 5, wherein the pressure exerted by the restraint device on the plurality of battery cells during charging of the plurality of battery cells is 3 MPa or less.

7. The restraint device according to claim 6, wherein the pressure exerted by the restraint device on the plurality of battery cells during charging of the plurality of battery cells is 2 MPa or less.

8. A restraint device as described in any one of claims 5 to 7, wherein the pressure exerted by the restraint device on the plurality of battery cells when the plurality of battery cells are discharging is 0.3 MPa or more.

9. The restraint device according to claim 8, wherein the pressure exerted by the restraint device on the plurality of battery cells during discharge of the plurality of battery cells is 0.5 MPa or more.

10. A restraint device as described in any one of claims 1 to 9, wherein the restraint member includes a first restraint member having a first plate-shaped member and a first frame member, and a second restraint member having a second plate-shaped member and a second frame member, and the fixing member fixes the lithium metal battery in a clamped and pressurized state between the first restraint member and the second restraint member.

11. A battery system comprising: a restraint device according to any one of claims 1 to 10; and the lithium metal battery.

12. An aircraft comprising: a battery system as claimed in claim 11; and a thrust generating device which generates thrust by utilizing the electrical energy stored in the battery system.

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