Secondary battery

Abstract

This secondary battery 100 comprises: a housing 1; a module battery 2 that is housed in the housing 1, where the module battery 2 has a heat insulation structure casing 20 which has an opening in an upper part thereof and which has accommodated therein an assembled battery configured from a plurality of unit cells 21, a heat insulation structure lid body 25 which closes the opening of the casing 20, and a duct 26 which is installed at least between the casing 20 and the lid body 25; a fan 3 that feeds cooling air 5 into the duct 26; and a cooling control device 4 that causes the fan 3 to rotate when the internal temperature and / or discharge output of the module battery 2 reaches a prescribed value or more, wherein a control mode of the cooling control device 4 includes a rotation suppression mode that is performed for a prescribed period from the start of rotation of the fan 3 and that suppresses the operation rate of the fan 3 to 70% or less.

Description

Secondary battery

[0001] The present invention relates to a secondary battery in which a module battery is housed in a container.

[0002] Patent Document 1 below discloses a secondary battery in which a plurality of module batteries (assembled batteries) are housed in a container.

[0003] Patent Document 2 below discloses that a module battery comprises: a heat-insulating casing that has an opening at an upper portion and houses an assembled battery composed of a plurality of unit cells therein; a heat-insulating lid that closes the opening of the casing; a duct disposed at least between the casing and the lid; and a fan that sends cooling air into an interior of the duct. Further, as control methods for the fan, the following first to fourth control methods are disclosed. In the first control method, an air flow rate is adjusted by changing the rotational speed of the fan or an average air flow rate is adjusted by an ON / OFF duty ratio of the driving time of the fan, so that the amount of heat radiation can be controlled according to the temperature: for example, when the temperature of the module battery is low, the air flow rate is decreased, and when the temperature rises, the air flow rate is increased, based on the internal temperature value of the module battery. In the second control method, a discharge waveform of the battery calculated based on a predicted load variation and a predicted power generation fluctuation amount is estimated, a required heat radiation amount is predicted, for example, by increasing the air flow rate when the discharge output is high or the discharge duration is long, and control is performed by adjusting the air flow rate through changing the rotational speed of the fan or adjusting the average air flow rate through the ON / OFF duty ratio of the driving time of the fan. In the third control method, the resistance value of the module battery is calculated from a voltage value and a current value during operation, an internal heat generation amount is calculated based on a pre-estimated discharge waveform to predict the required heat radiation amount, and control is performed by adjusting the air flow rate through changing the rotational speed of the fan or adjusting the average air flow rate through the ON / OFF duty ratio of the driving time of the fan. In the fourth control method, the resistance value of the module battery is estimated from the temperature during operation and the operation cycle, an internal heat generation amount is calculated based on a pre-estimated discharge waveform to predict the required heat radiation amount, and control is performed by adjusting the air flow rate through changing the rotational speed of the fan or adjusting the average air flow rate through the ON / OFF duty ratio of the driving time of the fan.

[0004] International Publication No. 2020 / 184332 International Publication No. 2015 / 056739

[0005] When controlling a fan using the control method described in Patent Document 2, with multiple module batteries housed in a housing as described in Patent Document 1, it was found that the following new problems arise. Specifically, when the fan is stopped, hot air accumulates inside the module batteries. In this state, if the fan is rotated at a high operating rate from the start of rotation, hot air leaks from the joints of the duct, causing the internal temperature of the housing to rise.

[0006] This invention was made to solve the above-mentioned problems, and one of its objectives is to provide a secondary battery that can suppress the rise in internal temperature of the housing.

[0007] <1> In one embodiment, the present invention relates to a secondary battery comprising: a housing; a module battery housed in the housing, having an opening at the top and containing a battery assembly composed of a plurality of single cells inside; a lid with an insulating structure that closes the opening of the housing; a duct installed at least between the housing and the lid; a fan that blows cooling air into the duct; and a cooling control device that rotates the fan when the internal temperature and / or discharge output of the module battery exceeds a predetermined value, wherein the control modes of the cooling control device include a rotation suppression mode that is performed for a predetermined period from the start of rotation of the fan and suppresses the operating rate of the fan to 70% or less.

[0008] <2> The present invention may relate to the secondary battery described in paragraph 1, wherein the operating rate of the fan in the rotation suppression mode is 25% or more.

[0009] <3> The present invention may relate to the secondary battery described in paragraph 1 or 2, wherein the rotation suppression mode is performed for a period of 60 minutes or less from the start of rotation of the fan.

[0010] According to one embodiment of the secondary battery of the present invention, a rotation suppression mode is included in the control mode of the cooling control device, which is performed for a predetermined period from the start of fan rotation and suppresses the fan's operating rate to 70% or less, thereby suppressing the rise in the internal temperature of the housing.

[0011] This is a schematic front perspective view showing a secondary battery according to an embodiment of the present invention. This is a schematic rear perspective view showing the secondary battery of Figure 1. This is a schematic cross-sectional view of the module battery of Figure 1.

[0012] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to each embodiment, and can be materialized by modifying the components without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in each embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, components from different embodiments may be appropriately combined.

[0013] Figure 1 is a schematic front perspective view showing a secondary battery 100 according to an embodiment of the present invention, Figure 2 is a schematic rear perspective view showing the secondary battery 100 of Figure 1, and Figure 3 is a schematic cross-sectional view of the module battery 2 of Figure 1.

[0014] As shown in Figures 1 and 2, the secondary battery 100 of this embodiment includes a housing 1, a plurality of module batteries 2, a plurality of fans 3, and a cooling control device 4.

[0015] The housing 1 is made up of, for example, a container. The housing 1 has a rectangular parallelepiped shape as a whole and has a bottom plate 10, a front plate 11, a rear plate 12, a pair of side plates 13, and a top plate 14. As shown in Figure 1, the bottom plate 10 is provided with an openable and closable air intake 10a. As shown in Figure 2, the rear plate 12 is provided with a plurality of exhaust ports 12a. As will be described later, the cooling air 5 drawn in from the air intake 10a is sent into the interior of each module battery 2, and the cooling air 5 that has passed through each module battery 2 is discharged from the exhaust ports 12a.

[0016] Multiple battery modules 2 are housed in the housing 1. As shown in Figure 3, each of the battery modules 2 in this embodiment includes a housing 20, multiple individual cells 21, a heater 22, silica sand 23, a temperature sensor 24, a cover 25, and a duct 26.

[0017] The housing 20 is a box-shaped member having an opening at the top. The housing 20 is placed on a base 15 provided inside the containment 1. The base 15 is not shown in Figure 1. The housing 20 has a bottom wall 20a and a side wall 20b extending upward from the outer edge of the bottom wall 20a. The housing 20 has an insulating structure. Specifically, the bottom wall 20a and the side wall 20b are made of a plate material such as stainless steel plate, and they themselves are formed in a box shape with a hollow section. The hollow section is an airtight sealed space, and the hollow section can communicate with the outside space by a vacuum valve (not shown). The hollow section may be filled with a porous insulating board made of glass fibers solidified into a plate shape with adhesive.

[0018] Multiple individual cells 21 are housed inside the casing 20. The multiple individual cells 21 are connected to each other in series and / or in parallel to form a battery cluster.

[0019] The heaters 22 are located at the bottom and sides of the housing 20. The heat from the heaters 22 can raise the temperature inside the housing 20.

[0020] Silica sand 23 is filled in the gaps between the housing 20 and the individual cells 21, and in the gaps between the individual cells 21. The silica sand 23 can transfer heat from the heater 22 to the individual cells 21, and can also absorb the heat generated by the individual cells 21.

[0021] The temperature sensor 24 is located inside the housing 20 and measures the temperature inside the housing 20. The temperature measured by the temperature sensor 24 is treated as the temperature of the module battery 2. The temperature sensor 24 includes a bottom temperature sensor 24a and a side temperature sensor 24b. The bottom temperature sensor 24a is located at a predetermined position in the center of the bottom of the housing 20, away from a heater 22 provided at the bottom of the housing 20 by a distance of, for example, 3 mm to 15 mm. The side temperature sensor 24b is located at a predetermined position in the center of the side of the housing 20 (center in the vertical and horizontal directions), away from a heater 22 provided at the side of the housing 20 by a distance of, for example, 3 mm to 15 mm. Although not limited to this, the higher of the temperature measured by the bottom temperature sensor 24a and the temperature measured by the side temperature sensor 24b may be treated as the temperature of the module battery 2.

[0022] The lid 25 is positioned above the housing 20 so as to close the opening at the top of the housing 20. The lid 25 has a flat top wall 25a that is larger than the opening at the top of the housing 20, and a canopy portion 25b that extends downward from the outer edge of the top wall 25a. The lid 25 also has a thermal insulation structure similar to the housing 20 described above. Specifically, the top wall 25a and the canopy portion 25b are made of a plate material such as a stainless steel plate, and they themselves are formed in a box shape with a hollow section. The hollow section is an airtight sealed space, and the hollow section can communicate with the outside space by a vacuum valve (not shown). The hollow section may be filled with a porous thermal insulation board made of glass fibers solidified into a plate shape with adhesive.

[0023] The duct 26 is a component for passing cooling air 5 into the inside of the module battery 2, and is positioned at least between the housing 20 and the cover 25. The duct 26 enables heat exchange between the heat generated by the module battery 2 and the cooling air 5. The duct 26 may be made of metal.

[0024] The duct 26 has a cooling air inlet 26a, a heat transport section 26b, and a cooling air outlet 26c. The cooling air inlet 26a is the part into which the cooling air 5 is introduced. The cooling air inlet 26a is located on the side of the housing 20 and extends to the top of the housing 20 through the inside of the overhang 25b of the lid 25. The heat transport section 26b is located downstream of the cooling air inlet 26a in the direction of the cooling air 5 flow and is located between the housing 20 and the lid 25 (top wall 25a). Heat exchange between the heat generated by the module battery 2 and the cooling air 5 is mainly carried out in the heat transport section 26b. The cooling air outlet 26c is the part into which the cooling air 5 is discharged. The cooling air outlet 26c is located downstream of the heat transport section 26b in the direction of the cooling air 5 flow and extends downward from the heat transport section 26b through the inside of the overhang 25b of the lid 25.

[0025] Fan 3 is provided for each of the multiple battery modules 2 and blows cooling air 5 into the interior of each of the multiple battery modules 2. Fan 3 is attached to the cooling air inlet 26a of the duct 26 and blows cooling air 5 into the interior of the duct 26. Fan 3 blows the air that has entered the interior of the housing 1 through the intake port 10a (see Figure 1) into the interior of the battery modules 2 as cooling air 5. The cooling air outlet 26c of the duct 26 is connected to the exhaust port 12a of the housing 1, and the cooling air 5 after heat exchange is discharged directly to the outside of the housing 1.

[0026] The cooling control device 4 is connected to the fan 3 of each of the multiple module batteries 2. In this embodiment, the cooling control device 4 rotates the fan 3 when the internal temperature and / or discharge output of the module battery 2 exceeds a predetermined value. The cooling control device 4 may rotate the fan 3 when the internal temperature and / or discharge output of the module battery 2 exceed a predetermined value. For example, the cooling control device 4 rotates the fan 3 when the internal temperature of the module battery 2 reaches 315°C or higher and the discharge output reaches 80% or higher of the rated output.

[0027] The cooling control device 4 of this embodiment includes a rotation suppression mode that is performed for a predetermined period from the start of rotation of the fan 3 and suppresses the operating rate of the fan 3 to 70% or less. When the fan 3 is stopped, hot air accumulates in the module battery 2. If the fan 3 is rotated at a high operating rate from the start of rotation, hot air may leak from the joints of the duct 26, causing the internal temperature of the housing 1 to rise. By performing the rotation suppression mode for a predetermined period from the start of rotation of the fan 3, the rise in the internal temperature of the housing 1 can be suppressed.

[0028] The utilization rate of fan 3 may be the ratio of fan 3 operation to maximum capacity. The utilization rate of fan 3 may be the ON / OFF duty cycle of the power supplied to fan 3. When the utilization rate of fan 3 is 70% or less, the period during which power is supplied to fan 3 within a predetermined period is 70% or less, and power supply to fan 3 is stopped during the other periods. The utilization rate of fan 3 may be the ratio of fan 3's operating speed to its maximum rotational speed. When the utilization rate of fan 3 is 70% or less, the operating speed of fan 3 is limited to 70% or less of its maximum rotational speed.

[0029] In rotation suppression mode, the operating rate of the fans 3 of all module batteries 2 is suppressed to 70% or less. For example, if the temperatures of multiple module batteries 2 differ from each other, and the operating rate of each fan 3 is determined based on the highest temperature among the multiple module batteries 2, then by implementing rotation suppression mode, the operating rate of the fan 3 of the module battery 2 with the highest temperature is suppressed to 70% or less. The operating rates of the fans 3 of the other module batteries 2 are set to the smaller of the operating rate reduced from the original operating rate of the fan 3 of the module battery 2 with the highest temperature based on the temperature difference, and the operating rate set in rotation suppression mode (70% or less). The cooling control device 4 may reduce the operating rate by 5% for every 1°C temperature difference. For example, if the original operating rate of the fan 3 of the module battery 2 with the highest temperature is 100%, and the temperature difference between the temperature of a certain module battery 2 and the highest temperature is 10°C, then the operating rate of the fan 3 of that module battery 2 based on the temperature difference will be 50%. The cooling control device 4 may determine the operating rate of the fan 3 of the module battery 2 by comparing the operating rate of the fan 3 based on the temperature difference (50%) with the operating rate set in rotation suppression mode (70% or less). The operating rates of the fan 3 of the module battery 2 may also be determined separately (independently of each other).

[0030] In rotation suppression mode, it is preferable to keep the operating rate of fan 3 below 60%, and more preferably below 50%. This makes it possible to more reliably suppress the rise in the internal temperature of housing 1.

[0031] In rotation suppression mode, it is preferable to set the operating rate of the fans 3 for all module batteries 2 to 25% or higher. By setting the operating rate of the fans 3 to 25% or higher in rotation suppression mode, it is possible to reduce the risk that the hot air inside the module batteries 2 will not be sufficiently discharged during rotation suppression mode, and that when the rotation suppression mode ends and the fan operating rate is set to 100%, the hot air inside the module batteries 2 will leak out and the internal temperature of the housing 1 will rise. However, even if the operating rate of the fans 3 is less than 25%, it is thought that the rise in the internal temperature of the housing 1 after the end of rotation suppression mode can be suppressed by taking measures such as gradually increasing the operating rate of the fans 3 as the end of rotation suppression mode approaches or after the end of rotation suppression mode.

[0032] The rotation suppression mode is performed for a period of 60 minutes or less from the start of fan 3 rotation. This reduces the risk of insufficient cooling of the module battery 2 and reduces the risk of the module battery 2's temperature exceeding the upper limit of the operating temperature range, such as 340°C. Preferably, the rotation suppression mode is performed for a period of 30 minutes or more from the start of fan 3 rotation. This more reliably suppresses the rise in the internal temperature of the housing 1.

[0033] The control modes of the cooling control device 4 in this embodiment further include a rotation unsuppressed mode or a normal mode, which are performed after a predetermined period has elapsed since the fan 3 started rotating. In the rotation unsuppressed mode, the operating rate of the fan 3 is increased to more than 70%. As described above, if the temperatures of the multiple module batteries 2 differ from each other, and the operating rate of each fan 3 is determined based on the highest temperature among the multiple module batteries 2, then in the rotation unsuppressed mode, the operating rate of the fan 3 of the module battery 2 with the highest temperature is increased to more than 70%. In the rotation unsuppressed mode, the operating rate of the fan 3 of the module battery 2 with the highest temperature may be increased to 100%. In the rotation unsuppressed mode, the operating rates of the fans 3 of the other module batteries 2 may be lower than the operating rate of the fan 3 of the module battery 2 with the highest temperature based on the temperature difference, and may be 70% or less.

[0034] The operation of the fans 3 of all module batteries 2 can be stopped when the temperature of all module batteries 2 falls below a threshold, or when the discharge output of the entire secondary battery 100 falls below a threshold. Discharge stopping is included when the discharge output falls below the threshold.

[0035] Although preferred embodiments of the present invention have been described in detail above with reference to the attached drawings, the present invention is not limited to these examples. It is clear to any person with ordinary skill in the art to which the present invention belongs that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these are also understood to fall within the technical scope of the present invention.

[0036] The present invention will be described more specifically below with reference to examples. The present invention is not limited to these examples.

[0037] A secondary battery was prepared, consisting of a container housing multiple module batteries. Temperature sensors were installed inside the container and modules, and the entire capacity of the module batteries was discharged at rated output. During this time, the internal temperature changes of the container and module batteries were investigated while varying the presence or absence of rotation suppression mode (fan operating rate) and the duration of its implementation. The results are shown in the table below.

[0038]

[0039] The following were used as the container, module battery, and temperature sensor: • Container: Dimensions: Width 6058 mm, Height 2591 mm, Depth 2690 mm, Weight 5.9 t Material: SPA-H (weathering steel) • Module battery: Dimensions: Width 1500 mm, Height 802 mm, Depth 2000 mm, Weight 2.3 t Material: SUH409L (heat-resistant steel) Number of units: 6 units (3 module batteries arranged side-by-side in two tiers) • Temperature sensor to measure the temperature inside the container: A total of 2 platinum resistance thermometers were installed between the upper tier of module batteries. • Temperature sensor to measure the temperature inside the module battery: A bottom temperature sensor was installed in the center of the bottom of the module battery housing.

[0040] When the internal temperature of any module battery reaches 315°C or higher and the discharge output reaches 80% or more of the rated output, the fans of all module batteries are operated.

[0041] When the rotation suppression mode is not implemented, the operating rate of the fan of the module battery with the highest temperature is set to 100%. At this time, the operating rate of the fan of another module battery is determined based on the difference between the temperature of said module battery and the highest temperature. Specifically, the operating rate is reduced by 5% for every 1°C of temperature difference. The fan is operated until the module battery reaches the end of discharge.

[0042] When the rotation suppression mode is implemented, as shown in Table 1, the operating rate of the fan of the module battery with the highest temperature is set to a predetermined value of 75% or less. For the operating rate of the fan of another module battery, the smaller value is selected between: an operating rate obtained by reducing 5% from 100% for every 1°C difference between the temperature of said module battery and the highest temperature, and said predetermined value of 75% or less. After the rotation suppression mode ends, the fan is operated at an operating rate of 100% until the module battery reaches the end of discharge.

[0043] When a module battery discharges at the rated output, the heat generated by discharge is greater than the heat exhausted by the fan, so the internal temperatures of the container and the module battery rise. Table 1 shows the maximum values of the internal temperatures of the container and the module battery (the respective internal temperatures when the module battery reaches the end of discharge) during the period until the module battery reaches the end of discharge.

[0044] Regarding the internal temperature of the container: "×" indicates that the maximum value of the container internal temperature is 95°C or higher; "△" indicates that the maximum value of the container internal temperature is lower than 95°C and 90°C or higher; "○" indicates that the maximum value of the container internal temperature is lower than 90°C and 88°C or higher; "◎" indicates that the maximum value of the container internal temperature is lower than 88°C.

[0045] Regarding the internal temperature of the module battery, "△" indicates that the maximum value of the internal temperature of the module battery is less than 335°C and not less than 333°C, "○" indicates that the maximum value of the internal temperature of the module battery is less than 333°C and not less than 330°C, and "◎" indicates that the maximum value of the internal temperature of the module battery is less than 330°C.

[0046] As shown in No. 1, when the rotation suppression mode is not implemented, and as shown in No. 2, when the operating rate of the fan of the module battery with the highest temperature is set to more than 70%, the internal temperature of the container in the rotation suppression mode is marked as "×". It is considered that hot air leakage could not be reduced when the fan operating rate was set to 75%. In contrast, as shown in Nos. 3 to 9, when the operating rate of the fan of the module battery with the highest temperature is set to 70% or less, the internal temperature of the container in the rotation suppression mode is marked as "△" to "◎". From these results, it was confirmed that implementing the rotation suppression mode that suppresses the fan operating rate to 70% or less can suppress the rise of the internal temperature of the container (accommodating body).

[0047] On the other hand, as shown in No. 7, when the operating rate of the fan of the module battery with the highest temperature is set to less than 25%, the internal temperature of the container after the end of the rotation suppression mode is marked as "×". This is considered to be because when the fan operating rate is less than 25%, the operating rate of the fan is too low to sufficiently discharge hot air inside the module battery, and the hot air inside the module battery leaks after the rotation suppression mode ends and the fan operating rate is returned to 100%. In contrast, as shown in Nos. 3 to 6, 8 and 9, when the fan operating rate is set to 25% or more, the internal temperature of the container after the end of the rotation suppression mode is marked as "△" or "◎". From this result, it was confirmed that it is preferable to set the fan operating rate in the rotation suppression mode to 25% or more. It should be noted that even if the fan operating rate is set to less than 25%, it is considered that the rise of the internal temperature of the container (accommodating body) after the end of the rotation suppression mode can be suppressed if measures such as gradually increasing the fan operating rate as the end of the rotation suppression mode approaches are adopted.

[0048] Examples No. 5, 8, and 9 show cases where the fan operating rate was fixed at 50%, and the duration of the rotation suppression mode was varied. When the duration was set to 30 minutes and 60 minutes, as in No. 5 and 8, the internal temperature of the module battery was "◎" or "〇", but when the duration was set to 120 minutes, as in No. 9, the internal temperature of the module battery was "△". From these results, it was found that it is preferable to set the duration to 60 minutes or less in order to reduce the risk of insufficient cooling of the module battery.

[0049] 1: Enclosure 2: Module battery 3: Fan 4: Cooling control device 5: Cooling air 20: Enclosure 21: Single cell 25: Cover 26: Duct 100: Secondary battery

Claims

1. A secondary battery comprising: a housing; a module battery housed in the housing, having an opening at the top and containing a battery assembly composed of multiple single cells inside, a heat-insulating housing; a heat-insulating lid that closes the opening of the housing; and a duct installed at least between the housing and the lid; a fan that blows cooling air into the duct; and a cooling control device that rotates the fan when the internal temperature and / or discharge output of the module battery exceeds a predetermined value, wherein the control modes of the cooling control device include a rotation suppression mode that is performed for a predetermined period from the start of fan rotation and limits the operating rate of the fan to 70% or less.

2. The secondary battery according to claim 1, wherein the operating rate of the fan in the rotation suppression mode is 25% or more.

3. The secondary battery according to claim 1 or 2, wherein the rotation suppression mode is performed for a period of 60 minutes or less from the start of rotation of the fan.

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