JP7151592B2 - power storage device - Google Patents

Description

The present disclosure relates to power storage devices.

Generally, a power storage device includes a plurality of power storage cells arranged in one direction and a bus bar electrically connecting adjacent power storage cells (Japanese Patent Application Laid-Open No. 2001-43902).

A storage cell includes a housing case, an electrode assembly, and an electrolytic solution. The storage case is made of metal such as aluminum. The electrode assembly and electrolyte are housed in a housing case.

Each storage cell includes a positive electrode terminal and a negative electrode terminal provided on the upper surface of the storage case, and the busbar electrically connects adjacent storage cells in series. A high-voltage circuit is formed by a plurality of storage cells and a plurality of bus bars.

JP-A-2001-43902

In the power storage device described above, if an impact is applied from the outside, an internal short circuit may occur within the power storage cell, resulting in thermal runaway of the power storage cell. When thermal runaway occurs in a specific storage cell, the temperature of storage cells adjacent to the thermally runaway storage cell tends to rise, and the adjacent storage cells also tend to undergo thermal runaway. In this way, there is a risk that the thermally runaway storage cells may spread in the storage device.

Therefore, in order to suppress the spread of thermal runaway, it is conceivable to discharge a storage cell having a high SOC (state of charge) when it is detected that thermal runaway has occurred. This is because a storage cell with a low SOC is less likely to undergo thermal runaway than a storage cell with a high SOC, so the storage cell with a high SOC is discharged to suppress the spread of storage cells that are subject to thermal runaway.

However, if electrical continuity is broken in a storage cell in which thermal runaway has occurred, the electrical circuit including this storage cell is broken, making it impossible to discharge other storage cells.

The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a storage battery capable of ensuring discharge of other storage cells even when thermal runaway occurs in a specific storage cell. to provide the equipment.

A power storage device includes a power storage cell, a first bus bar and a second bus bar provided in the power storage cell, and a first insulating member and a second insulating member provided in the power storage cell. and a first terminal and a second terminal provided in the housing case, wherein the first bus bar is provided at the first terminal and the second bus bar is provided at the second terminal. The first insulating member and the second insulating member are provided in the housing case, and the first bus bar is a first pressing portion that presses the first insulating member toward the housing case. and the second bus bar includes a second pressing portion that presses the second insulating member toward the housing case.

According to the power storage device described above, when the temperature of the first power storage cell rises, the first insulating member and the second insulating member melt or soften. Since the first pressing portion presses the first insulating member against the housing case, the first pressing piece pushes away the softened insulating member, and the first pressing portion comes into contact with the housing case. Similarly, the second pressing portion also contacts the storage case.

When the first pressing portion and the second pressing portion contact the highly conductive housing case, the first terminal and the second terminal are electrically connected through the housing case. As a result, even if the storage cell thermally runs out of control and an electrical disconnection occurs in the first storage cell, electrical continuity between the first terminal and the second terminal can be secured, and the storage cell can be closed. It is possible to suppress electrical disconnection of the included electric circuit.

According to the power storage device according to the present disclosure, it is possible to ensure discharge of other power storage cells even when thermal runaway occurs in a specific power storage cell.

1 is a block diagram schematically showing vehicle 1 equipped with power storage device 2 according to the present embodiment. FIG. 1 is a side view schematically showing a vehicle 1; FIG. 2 is a side cross-sectional view schematically showing the power storage device 2. FIG. 2 is an exploded perspective view showing a power storage device 2; FIG. FIG. 3 is a plan view when a part of the power storage module 16 is viewed from above. 6 is a cross-sectional view taken along line VI-VI shown in FIG. 5; FIG. 4 is a plan view showing a busbar 42; FIG. FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7; FIG. 4 is a flow chart showing discharge control; FIG. 5 is a cross-sectional view showing a positive terminal 54 and a portion positioned therearound;

A power storage device according to the present embodiment will be described with reference to FIGS. 1 to 10. FIG. Among the configurations shown in FIGS. 1 to 10, the same or substantially the same configurations are denoted by the same reference numerals, and overlapping descriptions are omitted.

FIG. 1 is a block diagram schematically showing a vehicle 1 equipped with a power storage device 2 according to this embodiment.

Vehicle 1 includes power storage device 2 , SMR 3 , PCU 4 , rotating electric machine 5 , power transmission mechanism 6 , and wheels 7 . Further, the vehicle 1 includes a heater 8 , an air conditioner 9 , a DCDC converter 10 , a display device 11 , an ECU 12 , an auxiliary battery 13 , a cooling device 14 and a discharger 15 .

SMR 3 is electrically connected to power storage device 2 . PCU4 is connected to SMR3 by power lines PL1 and PL2. The rotating electric machine 5 is electrically connected to the PCU 4 . The power transmission mechanism 6 is mechanically connected to the rotor of the rotating electric machine 5 and the wheels 7 .

PCU 4 includes a converter and an inverter. PCU 4 boosts the DC power supplied from power storage device 2 and further converts it into AC power. Then, the PCU 4 supplies AC power to the rotating electric machine 5 . The rotating electric machine 5 generates driving force by AC power supplied from the PCU 4 . The power transmission mechanism 6 transmits the driving force transmitted from the rotating electric machine 5 to the wheels 7 .

Heater 8, air conditioner 9, and DCDC converter 10 are electrically connected to power line PL1 and power line PNL1 between SMR3 and PCU4. The heater 8 warms the air in the passenger compartment. The air conditioner 9 cools the air in the vehicle compartment when driven. DCDC converter 10 steps down the voltage of the DC power supplied from power storage device 2 and supplies the voltage to auxiliary battery 13 .

The display device 11 is provided in the passenger compartment, is a device for notifying passengers of various types of information, and is electrically connected to the auxiliary battery 13 .

The ECU 12 is a control unit that controls driving of the SMR 3 , the PCU 4 , the heater 8 , the air conditioner 9 , the DCDC converter 10 , the display device 11 , the cooling device 14 and the discharger 15 .

FIG. 2 is a side view schematically showing the vehicle 1. FIG. The vehicle 1 includes a vehicle body 20 in which a storage room 21 and a passenger compartment 22 are formed.

The PCU 4 and the rotary electric machine 5 are housed in the housing chamber 21 . The passenger compartment 22 is a space in which crew members of the vehicle 1 board. The vehicle body 20 includes a floor panel 23 , and the floor panel 23 is a metal member that forms the bottom surface of the vehicle 1 .

Power storage device 2 is arranged on the lower surface side of power storage device 2 . FIG. 3 is a side sectional view schematically showing the power storage device 2. As shown in FIG.

Power storage device 2 includes a case 30 , a battery ECU 31 , a sensor 32 , a valve 33 , an air-permeable membrane 34 , a cooling device 14 , and a power storage module 16 .

Battery ECU 31 , sensor 32 , cooling device 14 , power storage module 16 , and SMR 3 are housed inside case 30 .

Cooling device 14 is a device that cools power storage module 16 . The sensor 32 measures the temperature inside the case 30 and transmits the measurement result to the ECU 12 through the battery ECU 31 . A plurality of sensors 32 are provided inside the case 30, and the sensors 32 measure the temperature inside the case 30. Specifically, the sensors 32 are thermistors.

The air-permeable membrane 34 is provided so as to block the through hole formed in the case 30 . The gas-permeable membrane 34 allows gas such as air to pass therethrough, while preventing foreign matter such as water from entering the case 30 from the outside. The air-permeable membrane 34 is, for example, Gore-Tex (registered trademark).

When the pressure difference between the internal pressure inside the case 30 and the pressure outside the case 30 becomes the first pressure difference, the air passes through the gas-permeable membrane 34 and flows between the inside of the case 30 and the outside of the case 30. circulate.

The valve 33 is a mechanical one-way valve, and exhausts the air inside the case 30 to the outside. When the internal pressure inside the case 30 increases and the pressure difference between the internal pressure inside the case 30 and the pressure outside the case 30 becomes the second pressure difference, the valve 33 opens. Note that the second pressure difference is greater than the first pressure difference.

FIG. 4 is an exploded perspective view showing the power storage device 2. As shown in FIG. Case 30 includes a lower cover 35 and an upper cover 36 . The lower cover 35 and the upper cover 36 are made of metal such as aluminum or resin containing carbon fiber.

The power storage device 2 includes a plurality of power storage modules 16, and each power storage module 16 is elongated in the vehicle width direction W. As shown in FIG. Each power storage module 16 includes a plurality of power storage cells 37, and the power storage cells 37 are arranged in the vehicle width direction W. As shown in FIG.

A heat insulating material 17 is provided between adjacent power storage modules 16 . The heat insulating material 17 is, for example, a sheet containing aerosilica gel.

FIG. 5 is a plan view when a part of the power storage module 16 is viewed from above. Electricity storage module 16 includes insulating members 40 and 41 and a plurality of bus bars 42 , 43 , 44 and 45 . The insulating member 40 and the insulating member 41 are formed elongated in the vehicle width direction W, and the insulating members 40 and 41 are arranged so as to pass through the upper surface of each storage cell 37 . The insulating member 40 and the insulating member 41 are spaced apart in the vehicle front-rear direction D. As shown in FIG.

A heat insulator 18 is also provided between each storage cell 37 . The heat insulator 18 is made of the same material as the heat insulator 17 .

Each bus bar 42, 43, 44, 45 is provided so as to electrically connect the storage cells 37 adjacent in the vehicle width direction W in series.

FIG. 6 is a cross-sectional view along line VI-VI shown in FIG. The storage cell 37 includes a storage case 50 , an electrode body 51 , a positive collector terminal 52 , a negative collector terminal 53 , a positive terminal 54 , a negative terminal 55 , and an electrolytic solution 56 .

The housing case 50 is made of a conductive metal material. The housing case 50 includes a case body 57 and a lid 58 . The case body 57 is formed to open upward. The lid 58 is welded to the case body 57 so as to close the opening of the case body 57 .

The electrode body 51 is housed in the housing case 50, and includes a positive electrode sheet, a separator, and a negative electrode sheet, with the separator disposed between the positive electrode sheet and the negative electrode sheet.

Electrode body 51 includes positive electrode 60 and negative electrode 61 . A positive electrode 60 is formed at one end of the electrode body 51 in the vehicle longitudinal direction D, and a negative electrode 61 is formed at the other end.

The positive collector terminal 52 electrically connects the positive electrode 60 and the positive terminal 54 , and the negative collector terminal 53 electrically connects the negative electrode 61 and the negative terminal 55 . The positive terminal 54 is provided on the upper surface of the lid 58 with the insulating member 62 interposed therebetween, and the negative terminal 55 is provided on the upper surface of the lid 58 with the insulating member 63 interposed therebetween. The insulating members 62 and 63 insulate the positive terminal 54 and the negative terminal 55 from the lid 58 .

FIG. 7 is a plan view showing the busbar 42. As shown in FIG. Busbar 42 includes a fixing portion 80 , a fixing portion 81 , and a connecting portion 82 .

The connecting portion 82 is formed to extend in the vehicle width direction W. As shown in FIG. A through hole 83 is formed at one end side of the connecting portion 82 in the vehicle width direction W, and the other end side of the connecting portion 82 is formed.

The fixing portion 80 is formed so as to protrude in the vehicle front-rear direction D at one end side of the connecting portion 82 , and the fixing portion 81 is formed so as to protrude in the vehicle front-rear direction D at the other end of the connecting portion 82 .

The fixing portion 80 includes a frame portion 85 and a pressing piece (pressing portion) 86 , and the fixing portion 81 includes a frame portion 87 and a pressing piece 88 . FIG. 8 is a cross-sectional view along line VIII-VIII in FIG.

Positive terminal 54 includes metal plate 65 and terminal 66 . The metal plate 65 and terminals 66 are provided on the upper surface of the insulating member 62 . Terminal 66 includes a head 70 and a shaft portion 71 .

The head 70 is arranged on the lower surface side of the metal plate 65 , and the shaft portion 71 is formed to protrude upward from the head 70 . Axial portion 71 is formed to pass through a through hole formed in metal plate 65 and protrude upward from the upper surface of metal plate 65 .

The busbar 42 is arranged on the upper surface of the metal plate 65 , and the shaft portion 71 is inserted into the through hole 83 of the busbar 42 .

A nut 72 is provided on the upper surface of the bus bar 42 . The nut 72 is screwed onto a threaded portion formed on the outer peripheral surface of the shaft portion 71 , and the busbar 42 is fixed to the upper surface of the metal plate 65 .

The fixed portion 80 is formed to protrude from the positive electrode terminal 54 toward the negative electrode terminal 55 . The pressing piece 86 is formed to extend downward from the inner peripheral surface of the frame portion 85 . Specifically, the pressing piece 86 is inclined from the negative electrode terminal 55 side toward the positive electrode terminal 54 side from the upper end portion to the lower end portion of the pressing piece 86 .

A lower end portion of the pressing piece 86 is in contact with the upper surface of the insulating member 40 , and the insulating member 40 electrically insulates the pressing piece 86 and the lid 58 . Here, the pressing piece 86 is elastically deformed, and the lower end portion of the pressing piece 86 presses the upper surface of the insulating member 40 downward.

Although the configuration of the fixing portion 80 has been described in detail, the fixing portion 81 shown in FIG. The fixing portion 81 is also formed with a pressing piece similarly to the fixing portion 80, and the pressing piece of the fixing portion 80 also presses the upper surface of the insulating member 40 downward. The busbars 43 , 44 , 45 are constructed similarly to the busbar 42 .

In the power storage device 2 configured as described above, an impact force may be applied from the outside. For example, when vehicle 1 collides with another vehicle or the like, a large impact force is applied to power storage device 2 .

In FIG. 6 , if an impact force is applied to the power storage device 2 and the power storage cell 37 is damaged, an internal short circuit or the like may occur within the electrode body 51 , for example.

When an internal short circuit occurs within the electrode body 51, the temperature of the electrode body 51 rises. When the temperature in the storage cell 37 rises, an exothermic reaction is promoted in the storage cell 37 and the internal pressure in the storage cell 37 rises. Then, the explosion-proof valve provided in the storage case 50 is opened, and the high-temperature, high-pressure gas blows out from the storage case 50 .

When gas is ejected from the thermally runaway storage cell 37 in this manner, the internal pressure of the case 30 of the storage device 2 shown in FIG. 3 increases. Then, when the pressure difference between the internal pressure inside the case 30 and the pressure outside the case 30 becomes greater than or equal to the second pressure difference, the valve 33 is opened. This suppresses an increase in the internal pressure inside the case 30 .

Here, a heat insulating material 17 is provided between each power storage module 16 and a heat insulating material 18 is provided between each power storage cell 37 . Therefore, heat transfer from the thermally runaway storage cell 37 to the surrounding storage cells 37 is suppressed, and thermal runaway of the plurality of storage cells 37 is suppressed.

If the plurality of storage cells 37 thermally run away and gas is ejected from the plurality of storage cells 37, the amount of gas supplied from the plurality of storage cells 37 into the case 30 is larger than the amount of exhaust gas exhausted from the valve 33. quantity is greater. As a result, the internal pressure inside the case 30 increases and the case 30 may be damaged.

On the other hand, in the power storage device 2 according to the present embodiment, the thermal runaway of the plurality of power storage cells 37 is suppressed by the heat insulating materials 17 and 18, and the case 30 is prevented from being damaged as described above. can be suppressed.

In FIG. 3, a plurality of sensors 32 are provided inside the case 30 . For example, sensor 32A is positioned above storage cell 37A. Then, when the high-temperature gas blows out from the storage cell 37A, the temperature measured by the sensor 32A increases.

When the temperature measured by the sensor 32A becomes higher than a predetermined threshold value, the ECU 12 controls to discharge the electric power stored in the storage cells 37 located around the storage cells 37A.

Specifically, the ECU 12 supplies electric power of the storage cells 37 located around the storage cells 37A in FIG. In particular, by driving the cooling device 14, it is possible to suppress the temperature rise of the storage cells 37 located around the storage cells 37A.

Note that the ECU 12 activates the discharger 15 when the SOC of the storage cells 37 positioned around the storage cell 37A is high. Discharger 15 includes a resistor 24 and a relay 25, and when relay 25 is turned ON, electric power stored in power storage device 2 can be discharged in a short period of time.

Note that when the amount of electricity stored in the storage cell 37 is lowered, even if the temperature of the storage cell 37 rises, thermal runaway of the storage cell 37 is less likely to occur.

Therefore, by supplying the amount of electricity stored in the storage cells 37 located around the storage cells 37A to the heater 8 or the like, thermal runaway of the storage cells 37 located around the storage cells 37 is suppressed.

Here, it may take several tens of minutes to several hours to lower the SOC of the storage cells 37 located around the storage cell 37A.

On the other hand, a heat insulating material 18 is arranged between each storage cell 37 , and a heat insulating material 17 is provided between each power storage module 16 . Therefore, before the discharge of the storage cells 37 located around the storage cells 37A is completed, the heat from the storage cells 37A prevents the storage cells 37 located around the storage cells 37A from becoming hot. can be done.

Although the case where the temperature measured by the sensor 32A is higher than the predetermined threshold has been described, the same control is executed when the temperature measured by the other sensor 32 is higher than the predetermined threshold. be.

FIG. 9 is a flow diagram showing discharge control. The ECU 12 acquires the temperature inside the case 30 (Step 10). Specifically, the ECU 12 receives the measured temperature measured by each sensor 32 from the plurality of sensors 32 .

The ECU 12 determines whether the temperature inside the case 30 is higher than a predetermined threshold (Step 20). Specifically, when the ECU 12 determines that the temperature measured by at least one of the plurality of sensors 32 is higher than a predetermined threshold value, the ECU 12 determines that the temperature inside the case 30 is higher than a predetermined threshold value. .

The ECU 12 performs corresponding control (Step 30). For example, the display device 11 shown in FIG. 1 is caused to display a display prompting the occupant to evacuate. Further, the driving of the PCU 4 is controlled so that the vehicle 1 travels for evacuation.

Then, the ECU 12 energizes the electric load with the electric power accumulated in the power storage device 2 (Step 40). Specifically, a sensor 32 that measures a temperature higher than a predetermined threshold is identified, and a storage cell 37 located below the sensor 32 is identified. Then, the storage cells 37 positioned around the identified storage cells 37 are supplied to the heater 8 and the like. Note that the control flow shown in FIG. 9 is repeatedly executed while the vehicle 1 is running.

In this manner, for example, when the storage cell 37A shown in FIG. 5 experiences thermal runaway, the electric power stored in the storage cells 37B and 37C is discharged.

On the other hand, in FIG. 6, electrical continuity between the positive electrode terminal 54 and the negative electrode terminal 55 may be broken in the storage cell 37A. For example, damage to the electrode assembly 51 may cause electrical disconnection between the positive electrode 60 and the negative electrode 61 . Moreover, the connection between the positive collector terminal 52 and the positive electrode 60 may be disconnected, or the connection between the negative collector terminal 53 and the negative electrode 61 may be disconnected.

In FIG. 5, storage cells 37B and 37C are electrically connected in series to storage cell 37A. Therefore, if the electrical continuity in the storage cell 37A is broken, the electrical connection between the storage cells 37A, 37B, and 37C and the electric load such as the heater 8 is broken.

On the other hand, in the power storage device 2 according to the present embodiment, the positive terminal 54 and the negative terminal 55 of the power storage cell 37A are electrically connected through the lid 58 when the power storage cell 37A thermally runs out of control. Specific actions will be described with reference to FIGS. 8 and 10 and the like. In FIG. 8, when the storage cell 37A thermally runs away, the temperature of the lid 58 rises. Then, the insulating member 40 provided on the upper surface of the lid 58 melts.

The pressing piece 86 presses the upper surface of the insulating member 40 downward, and when the insulating member 40 melts, the lower end of the pressing piece 86 moves toward the upper surface of the lid 58 .

FIG. 10 is a cross-sectional view showing the positive terminal 54 and its peripheral portion. In addition, in the state shown in FIG. 10, the storage cell 37A is thermally runaway and the insulating member 40 is melted. As shown in FIG. 10 , the lower end of the pressing piece 86 is in contact with the lid 58 .

Also in FIG. 6, the portion of the insulating member 41 located on the lid 58 of the storage cell 37A is melted. Also in the bus bar 45 provided on the negative electrode terminal 55 of the storage cell 37A, the lower end of the pressing piece 89 contacts the lid 58 .

In this manner, the pressing pieces of the busbar 45 and the busbar 42 are in contact with the lid 58 , so that the positive terminal 54 and the negative terminal 55 are electrically connected through the lid 58 . Therefore, even if an electrical disconnection occurs in the storage cell 37A, the storage cell 37A and the storage cells 37B and 37C can maintain an electrically conductive state.

As a result, the electric power stored in the storage cells 37B and 37C located around the thermally runaway storage cell 37A can be supplied to the load such as the heater 8, thereby suppressing the thermal runaway of the storage cells 37B and 37C. It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims, and is intended to include all changes within the meaning and range of equivalents to the claims.

REFERENCE SIGNS LIST 1 vehicle 2 power storage device 5 rotary electric machine 6 power transmission mechanism 7 wheel 8 heater 9 air conditioner 10 converter 11 display device 13 auxiliary battery 14 cooling device 15 discharger 16 power storage module 17 , 18 heat insulating material, 20 vehicle body, 21 accommodation chamber, 22 vehicle interior, 23 floor panel, 24 resistance, 25 relay, 30 case, 32, 32A sensor, 33 valve, 34 ventilation membrane, 35 lower cover, 36 upper cover, 37, 37A, 37B, 37C Storage cell 40, 41, 62, 63 Insulating member 42, 43, 44, 45 Bus bar 50 Housing case 51 Electrode body 54 Positive electrode terminal 55 Negative electrode terminal 56 Electrolyte solution 57 Case main body 58 Lid 60 Positive electrode 61 Negative electrode 65 Metal plate 70 Head 71 Shaft 72 Nut 80, 81 Fixed part 82 Connecting part 83 Through hole 85, 87 Frame 86, 88, 89 pressing piece, D vehicle longitudinal direction, ECU31 battery, PL1, PNL1 power line, W vehicle width direction.

Claims (1)

a storage cell;
a first bus bar and a second bus bar provided in the storage cell;
a first insulating member and a second insulating member provided in the storage cell;
with
The storage cell includes a conductive housing case, and a first terminal and a second terminal provided in the housing case,
The first bus bar is provided at the first terminal, the second bus bar is provided at the second terminal,
The first insulating member and the second insulating member are provided in the housing case,
The first bus bar includes a first pressing portion that presses the first insulating member toward the storage case,
The power storage device, wherein the second bus bar includes a second pressing portion that presses the second insulating member toward the storage case,
The power storage device , wherein the first pressing portion and the second pressing portion push aside the softened first insulating member and the second insulating member and come into contact with the housing case when the temperature of the power storage cell rises .

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